Patent Description:
Methicillin-resistant Staphylococcus aureus (MRSA) refers to a group of Gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus. MRSA is responsible for several difficult-to-treat infections in humans. MRSA is any strain of S. aureus that has developed multiple drug resistance to beta-lactam antibiotics through horizontal gene transfer and/or natural selection. β-lactam antibiotics are a broad-spectrum group that include some penams (penicillin derivatives such as methicillin and oxacillin) and cephems such as the cephalosporins.

MRSA is common in hospitals, prisons, and nursing homes, where people with open wounds, invasive devices such as catheters, and weakened immune systems are at a greater risk of hospital-acquired infection. MRSA began as a hospital-acquired infection, but has become community-acquired, as well as livestock-acquired.

In recent studies MRSA could be identified in many surface waters, such as rivers and lakes, increasing the chances that MRSA will contaminate drinking water sources and can easily be transmitted to all kinds of sensitive areas, such as nursery schools, schools, hospitals, special-care homes, retirement homes and other health-care facilities.

This is especially dangerous, since common cleaning systems of sewage and sewage treatment plants are currently not always sufficiently equipped to filter or to eradicate multi-resistant germs out of the water.

One of the few countries not yet overwhelmed by MRSA is the Netherlands. An important part of the success of the Dutch strategy was the attempt to eradicate MRSA in patients before being dismissed from the hospital.

Thus, there is a great need of easy-to-use and effective eradication methods against MRSA, especially MRSA that resides on surfaces sensitive to conventional sterilization methods.

Methods for eradication of MRSA by light have been reported in the art. , for instance from <NPL>" and <NPL>". The so called "photosensitizer-method" is used widely in hospitals and other areas with elevated MRSA-risks (or other bacterial contaminations). This method makes use of photosensitizers, mostly dye molecules, that become excited when illuminated with light. When excited by light, these molecules produce reactive oxygen species, which then eradicate the bacteria.

However, not all reported methods using photosensitizers are sufficient to eradicate enough microorganisms to prevent infections effectively. This is because photosensitizers may not be concentrated enough to do significant damage. In addition, many photosensitizers are hydrophobic. This makes it difficult to disperse them in aqueous environments, where microorganisms typically exist (e.g. biofilms).

Another method in the art is called "ultraviolet germicidal irradiation" (UVGI), that uses short-wavelength ultraviolet (UVC) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions. UVGI is used in a variety of applications, such as food, air, and water purification.

UVGI devices can produce strong enough UVC light in circulating air or water systems to make them inhospitable environments to microorganisms such as bacteria, viruses, molds and other pathogens. UVGI can be coupled with a filtration system to sanitize air and water. The application of UVGI to disinfection has been an accepted practice since the mid-20th century. It has been used primarily in medical sanitation and sterile work facilities.

Increasingly, it has been employed to sterilize drinking and wastewater, as the holding facilities are enclosed and can be circulated to ensure a higher exposure to the UV. In recent years UVGI has found renewed application in air purifiers. Existing UVGI-methods use UV-light in the wavelength of around <NUM>, for example conventional germicidal UV lamps based on mercury-vapor lamps, radiate with a wavelength of <NUM>.

However, it has been reported that conventional germicidal UV lamps are harmful for the eye, produce pre-mutagenic UV-associated DNA lesions in human skin and are cytotoxic to exposed mammalian skin.

Thus, the danger of damaging effects, including even the induction of cancer or other mutagenic diseases, prevent the direct use of common UVGI-methods for eradication of MRSA on mammalian skin, such as for example the skin of patients, health care personnel or livestock.

It has been recently reported that far-UVC-light kills bacteria efficiently regardless of their drug-resistant proficiency, but without the skin- or eye-damaging effects associated with conventional germicidal UV exposure.

However, UV-absorption of UV-light at wavelengths of about <NUM> to about <NUM> is very high in otherwise transparent covers. For example, UV-light does not transmit well through conventional glasses at wavelengths beyond <NUM>. Conventional borosilicate glasses do not transmit light at wavelengths below <NUM>. Thus, these covers have the disadvantage that they are either impermissible for far-UV-light, or at least a high amount of energy is necessary to guarantee a sufficient UV-exposure of the treated surface, e.g. the treated skin. This high operational energy again results in significant energy dissipation and increases thermal stress to the cover, as well as to the whole device. The result is a reduced lifetime and increased maintenance cost of the device. <CIT>, <CIT>, <CIT> disclose UV transparent borosilicate glasses.

Thus, when assessing prior art methods, the problem was to provide a new UVGI-method, which allows the application of UV in the far UVC in order to facilitate direct MRSA-treatment of sensitive surfaces, such as mammalian skin or other materials that are UV-sensitive, such as certain gasses and/or liquids.

The problem is solved by the method according to claim <NUM> and a glass according to claim <NUM>.

UV radiation is able to split organic bonds. As a result, it is hostile to life by destroying biogenic substances. In addition, many plastics are damaged by ultraviolet radiation due to haze, embrittlement, and/or decay. Thus, UV-light can be harmful to a number of sensitive surfaces or other materials, which may be UV-sensitive, such as certain gasses and/or liquids.

In humans, excessive exposure to UV radiation can result in acute and chronic harmful effects on the eye's dioptric system and retina. The skin, the circadian and immune systems can also be affected. The skin and eyes are most sensitive to damage by UV at <NUM> to <NUM>.

Artificial UVC light of wavelengths around <NUM>, as being radiated for example by conventional UVGI-lamps, such as for example mercury-vapor lamps, produce pre-mutagenic UV-associated DNA lesions for example in human skin models and are cytotoxic to exposed mammalian skin. The eye is most sensitive to damage by UV in the lower UVC band at <NUM> to <NUM>. Radiation of this wavelength is almost absent from sunlight but is found in welder's arc lights and other artificial sources. Exposure to these can cause "welder's flash" or "arc eye" (photokeratitis) and can lead to cataracts, pterygium and pinguecula formation.

Thus, the wavelengths, which are applied according to the inventive method, are in the range of from <NUM> to <NUM>. Ultraviolet (UV) light of about <NUM> has similar antimicrobial properties as typical germicidal UV light (<NUM>), but without inducing damage to outer tissue coverings of higher animals, such as amphibian, reptile, bird, mammal or human skin. However, in other embodiments it may also be used to eradicate MRSA from the outer surface of mollusks (shells) and/or arthropods (exoskeleton).

The limited penetration distance of <NUM> light in biological samples (e.g. stratum corneum) compared with that of <NUM> light allows for the selective antimicrobial treatment without harming the treated surface, especially mammalian or human skin, such as the skin of a patient or health care professionals.

Considering the eye, the most important target from the perspective of UV risk is the lens. The lens is located distal to the cornea, which is sufficiently thick (<NUM>) such that penetration of <NUM> light through the cornea to the lens is essentially zero. Even if one considers effects on the cornea from the perspective of photokeratitis, any protective device against eye splash, which is now almost universal amongst surgical staff, would be expected to fully protect the cornea from <NUM> UV exposure.

The proposed bactericidal application of <NUM> UV light in the presence of humans is based on the fact that UV light at a wavelength of around <NUM> is very strongly absorbed by proteins (particularly through the peptide bond) and other biomolecules, so its ability to penetrate biological material is very limited. Thus, for example the intensity of <NUM> UV light is reduced by half in only about <NUM> of tissue, compared with about <NUM> at <NUM> and much longer distances for higher UV wavelengths. By contrast, <NUM> UV light is only minimally absorbed in water.

At the cellular level, bacteria are much smaller than almost any human cell. Typical bacterial cells are less than <NUM> in diameter, whereas typical eukaryotic cells range in diameter from about <NUM> to <NUM>.

It follows, that <NUM> UV light can penetrate throughout typical bacteria-cells but cannot penetrate significantly beyond the outer perimeter of the cytoplasm of typical eukaryotic cells, such as human cells, and will be drastically attenuated before reaching the eukaryotic cell nucleus.

By contrast, higher wavelength light from a conventional germicidal lamp can reach human cell nuclei without major attenuation. Based on these biophysical considerations, while radiation from a conventional UVC lamp is cytotoxic and mutagenic to both bacteria and human cells, <NUM> UV light is cytotoxic to bacteria, but much less cytotoxic or mutagenic to human cells.

UV-light of wavelengths significant below <NUM>, however, are not useful, because at these wavelengths a sufficient eradication of MRSA cannot be reached anymore. Furthermore, at wavelengths below <NUM>, UV reacts with oxygen and forms ozone, an effect which is not desired.

The UVC light in the range of about <NUM> to <NUM> eradicates bacteria efficiently regardless of their drug-resistant proficiency, but without the skin and eye damaging effects associated with conventional germicidal UV exposure.

The term "eradication" is used herein for any reduction of MRSA after treatment of more than <NUM>%, more than <NUM>%, more than <NUM>%, more than <NUM>%, or more than <NUM>% according to ISO <NUM>:<NUM>-<NUM>-<NUM>.

In order to achieve such an eradication, in one embodiment the invention pertains to a method wherein the UV-exposure of the MRSA and/or the surface to be treated is in the range from <NUM>,<NUM> to <NUM>,<NUM>µW·s/cm<NUM>, from <NUM>,<NUM> to <NUM>,<NUM>µW·s/cm<NUM>, from <NUM>,<NUM> to <NUM>,<NUM>µW·s/cm<NUM>, or from <NUM>,<NUM> to <NUM>,<NUM>µW·s/cm<NUM>. In one embodiment, the UV-exposure of at least about <NUM>,<NUM>µW·s/cm<NUM> results in a <NUM>% reduction of MRSA.

The methods of the present invention can be used for eradicating MRSA on all kinds of UV-sensitive material, which is sensitive to conventional UV-radiation of wavelengths above <NUM>. Such "UV-sensitive materials" may be any material where UV of wavelengths above <NUM>, above <NUM> and/or up to <NUM> is able to split organic or inorganic bonds. Such UV-sensitive material may include any plastics, which are damaged by ultraviolet radiation between <NUM> and/or up to <NUM> due to haze, embrittlement, and/or decay.

In another embodiment, the UV-sensitive material may be susceptible to crosslinking of monomers to produce specific polymers by UV-radiation above <NUM>, or above <NUM> and/or up to <NUM>. In yet another embodiment the UV-sensitive material may be a gas or a liquid, which is sensitive to UV above <NUM>, or above <NUM> and/or up to <NUM>.

In yet another embodiment, the UV-sensitive material may be a pharmaceutical composition, which is sensitive to UV above <NUM>, or above <NUM> and/or up to <NUM>.

In yet another embodiment, the UV-sensitive material may be a biological tissue surface, such as a skin of an insect, invertebrate, vertebrate, mammal or human, (e.g. mollusc, fish, amphibia, reptile, bird, mammal and/or human or a chitinous exoskeleton from an arthropod, such as a lobster or an insect).

Thus, the term "biological tissue surface" according to the definition of this invention encompasses all biological surfaces, which may be harmed by UV-radiation above <NUM>, or above <NUM> and/or up to <NUM>. In one embodiment, the invention includes biological surfaces which may be harmed by UV-radiation outside the wavelength range of <NUM> to <NUM>, and which are not harmed by UV-radiation within the wavelength range of <NUM> to <NUM>.

Within this invention the term "tissue" is used for any cellular organizational level between cells and a complete organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues.

Of course, especially tissue, which may be exposed to UV-radiation during an MRSA-eradication method should be encompassed. In most of the cases, those tissues will be epithelial tissues that are formed by cells that cover the organ surfaces, such as the surface of skin, the airways, the reproductive tract, and the inner lining of the digestive tract. The cells comprising an epithelial layer are linked via semi-permeable, tight junctions; hence, this tissue provides a barrier between the external environment and the organ it covers. In addition to this protective function, epithelial tissue may also be specialized to function in secretion, excretion and absorption. Epithelial tissue helps to protect organs from microorganisms, injury, and fluid loss.

Thus, methods of this invention include preferably those methods where conventional UVGI-methods may not be applicable or suitable, such as for example UV-treatment of MRSA residing on a UV-sensitive surface, such as for example skin tissue or where eye exposure to UV cannot be avoided.

The term "mammal" refers herein to any vertebrate animal constituting the class Mammalia and characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, <NUM>-<NUM> million years ago. There are around <NUM>,<NUM> species of mammals. The largest orders are the rodents, bats and Soricomorpha (shrews and others). The next three are the Primates (apes, monkeys, and others), the Cetartiodactyla (cetaceans and even-toed ungulates), and the Carnivora (cats, dogs, seals, and others). This definition of mammals also includes humans.

Thus, the term "mammal skin" refers to any skin of a mammal, including the skin of livestock, wherein the term "livestock" is commonly defined as domesticated animals raised in an agricultural setting to produce labor and commodities such as meat, eggs, milk, fur, leather, and wool, such as for example cattle, goats, horses, pigs and sheep.

Furthermore, the term "mammal skin" includes also the skin of humans, such as for example patients, health care professionals, people with weak or absent immune-system (elderly, children, post-surgery, post organ transplantation, HIV-positive, etc.), people with elevated potential exposure to MRSA, etc..

Prior art UV lamp covers are made of sapphire, synthetic quartz or quartz glass (fused silica glass). However, sapphire is very expensive as compared to other transparent materials and cannot be bent, molded, drawn or melt-fused like glasses or metals. In addition, the UV-absorption at UVC wavelengths is quite high with nearly no transmission at wavelengths below <NUM>.

In an embodiment of the present disclosure, the glass has a transmission of at least <NUM>%, better at least <NUM>% or at least <NUM>% at <NUM> and/or at least <NUM>% at wavelengths [λ] of <NUM>, <NUM> and/or <NUM> (measured at a thickness of <NUM>).

Quartz and fused silica glasses, due to their high melting point, have high fabrication costs as well, since temperature and effort for melting and blowing are much higher than for other standard glasses. Furthermore, any forms other than tubes must be ground and polished from large blocks. Besides the costs of production, these covers have the disadvantage that high amounts of energy are necessary to guarantee a sufficient UV-exposure of the treated object, gas or liquid.

The glasses of the present invention, however, are suitable for forming rods, sheets, discs, tubes and bars, produced by casting, Danner, Vello and/or down-draw processes.

Furthermore, due to the high operating temperature, sagging and slumping effects may occur over time and a surface-devitrification may become visible, especially when the temperature is cycled at high temperatures. This, however, increases the weathering effects in the cover even more, which increases the UV-absorption and necessitates even higher operation energies to guarantee a sufficient UV-exposure of the treated object, gas or liquid - a vicious circle.

The high operation energy results not only in increased thermal stress to the cover, but also to the whole device, which reduces its lifetime and increases maintenance costs.

The glasses of the present invention may have excellent optical properties. In an embodiment, the glass has a refractive index nd (λ = <NUM>) of <NUM> to <NUM>. The refractive index can be less than <NUM>.

The glasses described herein have excellent UV transmission. They may have one or more of the following optical properties:.

In an embodiment, the glass has a UV transmission in the wavelength region from <NUM> to <NUM> (measured at a thickness d = <NUM>) ranging from at least <NUM>% at <NUM> to at least <NUM>% at <NUM>. In one embodiment, the UV transmission ranges from at least <NUM>% at <NUM> to at least <NUM>% at <NUM>.

The glass and / or the glass article preferably has a transmission of at least <NUM>%, preferably at least <NUM>%, at least <NUM>%, or at least <NUM>% at a wavelength of <NUM>. In one embodiment, the transmission at <NUM> is at most <NUM>%, at most <NUM>% or at most <NUM>%. The transmission is measured in particular with a sample thickness of <NUM>.

For clarity: The indication that a transmission is measured at a certain wavelength does not mean that the glass is limited to the indicated thickness. Instead, the thickness indicates the thickness at which the transmission can be measured. The indication of a thickness for measurement ensures that the values can be compared. The skilled person will understand that glasses of any suitable thickness can be used in the glass covers and devices described hereinunder. In addition, the skilled person will understand that the transmission can be measured at a thickness other than <NUM>, and the transmission value at <NUM> can be calculated from such measurement.

The present invention makes use of and relates to new glasses and glass covers (lamp covers, LED cover glass) which show low UV-absorption (i.e. high UVC-transmission), thereby decreasing the operation energy and reducing the operation temperature. Furthermore, the new glasses and glass covers of this invention are comparably cheap and easy to manufacture, can be bent, molded, drawn or melt-fused to guarantee a manifold of shapes, and are resistant to most chemicals, as well as temperature and physical stress.

According to the invention, the glass has a transmission throughout the wavelength range of from <NUM> to <NUM> of at least <NUM>% (measured at a thickness of <NUM>), wherein the glass is a borosilicate glass having a total platinum content of not more than <NUM> ppm, in some embodiments also having a low iron and titanium content of less than <NUM> ppm each, and a hydrolytic resistance characterized by an extracted Na<NUM>O equivalent in µg per g glass determined according to ISO <NUM> of not more than <NUM>µg/g, not more than <NUM>µg/g, not more than <NUM>µg/g, not more than <NUM>µg/g, not more than <NUM>µg/g, not more than <NUM>µg/g or not more than <NUM>µg/g.

In one embodiment it has been found that Pt-contaminations (i.e. Pt<NUM>, Pt<NUM>+, Pt<NUM>+, and Pt<NUM>+, also referred to as "total platinum content") in the glass may reduce the UV-transmission between <NUM> and about <NUM>. Without being bound to theory, it is assumed that platinum-contamination in the glass may induce phase-separation by the formation of nuclei within the glass. The glasses of the present invention are borosilicate glasses, with none or very low metal contamination, especially Pt-contamination of below <NUM>, or below <NUM> ppm. In other embodiments between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> are preferred. In a further embodiment the glass is free of any Pt-contamination.

In yet a further embodiment it has been found that also TiO<NUM> contamination (also referred to as "titanium content") in the glass may further reduce the UV-transmission between <NUM> and about <NUM>. Thus, in one embodiment glasses with a TiO<NUM> content of <NUM> ppm or less, preferably <NUM> ppm or less are preferred. Preferably, the amount of TiO<NUM> should be below <NUM> ppm, below <NUM> ppm, below <NUM> ppm, or below <NUM> ppm. In other embodiments the TiO<NUM> content may be between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, or between <NUM> and <NUM> ppm. In optional compositions, a content of between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, or between <NUM> and <NUM> ppm is preferred. In a further embodiment the glass is free of any TiO<NUM>-contamination.

In yet a further embodiment it has been found that also Fe-contamination in the glass may further reduce the UV-transmission between <NUM> and about <NUM>. In this description, iron contents are expressed as parts by weight of Fe<NUM>O<NUM> in ppm. This value can be determined in a manner familiar to the person skilled in the art by determining the amounts of all iron species present in the glass and assuming for the calculation of the mass fraction that all iron is present as Fe<NUM>O<NUM>. For example, if <NUM> mmol of iron is found in the glass, the mass assumed for the calculation corresponds to <NUM> Fe<NUM>O<NUM>. This procedure takes into account the fact that the quantities of the individual iron species in the glass cannot be determined reliably or only with great effort. In some embodiments the glass contains less than <NUM> ppm Fe<NUM>O<NUM>, in particular less than <NUM> ppm, or less than <NUM> ppm. In an embodiment with a particularly low iron content, the content of Fe<NUM>O<NUM> is less than <NUM> ppm, less than <NUM> ppm, or less than <NUM> ppm. Optionally, the Fe<NUM>O<NUM> content is between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, or between <NUM> and <NUM> ppm. In some embodiments, the content can be between <NUM> and <NUM> ppm, or preferably between <NUM> and <NUM> ppm. In a further embodiment, the glass is free of any contamination with Fe<NUM>O<NUM>.

Thus, glasses have a sum of all contaminations with Pt, TiO<NUM> and Fe<NUM>O<NUM> of below <NUM> ppm, in another embodiment below <NUM> ppm, in another embodiment below <NUM> ppm. In other embodiments glasses are preferred with a sum of all contaminations between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm. In a further embodiment the glass is free of the contaminations with at least one, two, or up to all three of the metals selected from Pt, TiO<NUM> and/or Fe<NUM>O<NUM>.

Also other contaminations with transition elements and/or heavy metals such as lead, rhodium, cadmium, mercury and hexavalent chromium may be kept below <NUM> ppm, in another embodiment below <NUM> ppm. In other embodiments these contaminations may be kept between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, or between <NUM> and <NUM> ppm. In other embodiments, the level of these contaminations may be between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, between <NUM> and <NUM> ppm, or between <NUM> and <NUM> ppm. In a further embodiment the glass is free of any transition metal and/or heavy metal-contamination.

If a reference is made herein to a chemical element, then this statement refers to any chemical form, unless otherwise stated in the individual case. For example, the statement that the glass has a content of As of less than <NUM> ppm means that the sum of the mass fractions of the As species present (e.g. As<NUM>O<NUM>, As<NUM>O<NUM>, etc.) does not exceed the value of <NUM> ppm.

As used herein, the term "ppm" means parts per million on a weight-by-weight basis (w/w). Metal contaminations during the production process need to be avoided in order to produce glasses with suitable UV-transmission. Thus, the present invention may also pertain to methods to produce glasses with high UV-transmission.

In one embodiment, the glass of the present invention is a borosilicate glass with high UV-transmission and the following additional ranges of physical and chemical parameters.

Unlike quartz, the glasses of this invention have excellent melting properties, e.g. low transformation temperatures and working points. Examples of suitable glass parameters may be selected from a transformation temperature Tg (ISO <NUM>-<NUM>) below <NUM>, such as from <NUM> to <NUM>, in one embodiment between <NUM> and <NUM>; in another embodiment between <NUM> and <NUM>.

The glass may have a T<NUM> temperature, i.e. a glass temperature at a viscosity η in dPa*s of <NUM><NUM> (annealing point) (ISO <NUM>-<NUM>), between <NUM> and <NUM>, such as in one embodiment between <NUM> and <NUM>; in another embodiment between <NUM> and <NUM>. The glass may have a softening point, i.e. the temperature at which the viscosity is <NUM><NUM> dPa*s (softening point) (ISO <NUM>-<NUM>) between <NUM> and <NUM>, such as in one embodiment between <NUM> and <NUM>, in another embodiment between <NUM> and <NUM>. The glass may have a working point, i.e. of the temperature at which the viscosity is <NUM><NUM> dPa*s (working point) (ISO <NUM>-<NUM>) between <NUM> and <NUM>, in one embodiment such as between <NUM> and <NUM>; in another embodiment between <NUM> and <NUM>. The temperature-viscosity dependence expressed by one or more of these parameters goes along with the ability of the glass to be drawn or otherwise formed into any desired shape, including UV lamp covers and UV-LED covers.

Thus, in one embodiment the glass has a Tg of between <NUM> and <NUM>; a T<NUM> of between <NUM> and <NUM>; a softening point of between <NUM> and <NUM> and a working point of between <NUM> and <NUM>.

In another preferred embodiment the glass has a Tg of between <NUM> and <NUM>; a T<NUM> of between <NUM> and <NUM>; a softening point of between <NUM> and <NUM> and a working point of between <NUM> and <NUM>.

The glasses of the present invention may have a density ρ at <NUM> between <NUM> and <NUM>*cm-<NUM>. The low density makes the glass most suitable for mobile applications, e.g. mobile MRSA eradication equipment.

The glasses of the present invention may feature a thermal conductivity λw at <NUM> between <NUM> and <NUM> W * m-<NUM> * K-<NUM>, making it most suitable for use as lamp cover.

The UVC-glasses and the UVC-glass covers made thereof have the following additional features:
The term "solarization" refers to a phenomenon in physics where a material undergoes a change in light transmission after being subjected to high-energy electromagnetic radiation, such as ultraviolet light. Clear glass and many plastics will turn amber, green or other colors when subjected to X-radiation, and glass may turn blue after long-term solar exposure in the desert. Solarization may also permanently degrade a material's physical or mechanical properties, and is one of the mechanisms involved in the breakdown of plastics within the environment.

The glasses of the present invention may show a very good resistance against "solarization" (see example section) and, thus, are very suitable for the use as UV-glasses. "Solarization" is the reduction of transmission for light of different wavelength ranges caused by exposure to short-wave UV light. Solarization can make the glass either colored or completely opaque.

Thus, "solarization resistance" is the property of the glass to maintain a high transmission at a certain wavelength even after UV irradiation. It can be described by calculating the induced absorbance α(λ): <MAT> with T(λ)<NUM> = transmission before irradiation and T(λ)i = transmission after i hours of irradiation with a deuterium lamp. The smaller α(λ) is, the more resistant the glass is to solarization. The solarization resistance is stated herein for the wavelength <NUM>. For the specification of the solarization resistance, a sample thickness of about <NUM> to <NUM> is assumed in this specification. This means that the measurement takes place at this sample thickness. The claimed glass article itself may have a different thickness. The irradiation is carried out with a deuterium lamp. Deuterium lamps emit light up to a very short-wave UV range. The lamp used here has a cut-off wavelength of <NUM>. The power of the deuterium lamp can be about <NUM> W/m<NUM>. The following deuterium lamp (DUV) can be used: Heraeus Noblelight GmbH, Type V04, S-Nr. : V0390 <NUM> W, with MgF<NUM> filter for sufficient emission up to <NUM>.

The glasses used in this invention also show a very good hydrolytic resistance and high gas-tightness.

The phase separation factor is a measure of the property of the glass to change its hydrolytic resistance as defined in ISO <NUM> as a result of phase separation. Phase separation occurs when the glasses are fused due to the influence of temperature. It has been proven to be advantageous to select glasses with a phase separation factor as close to <NUM> as possible, so that the glass properties of a phase separated glass do not differ greatly from the raw glass in terms of its hydrolytic resistance. The phase separation factor is influenced by the composition of the glass, but also by its thermal history (cooling state).

The phase separation factor E is calculated as follows.

Therein, Equroh and Equent are the extracted Na<NUM>O equivalents in µg per g glass determined according to ISO <NUM>:<NUM>-<NUM> of the non-phase separated and phase separated glass, respectively. The phase separation factor is a property of the glass. This factor does not mean that the claimed glass has undergone phase separation, but that, if phase separation happens, the influence on hydrolytic stability is in the range given by the factor. Every glass can be analyzed for its phase separation factor. For that purpose, the extracted Na<NUM>O equivalents are determined in a phase separated specimen and a non-phase separated specimen. For the purpose of measurement, a "phase separated glass" is obtained by holding a glass specimen at <NUM> above the glass transition temperature (Tg) for <NUM> hours. This temperature treatment ensures a certain level of phase separation.

The hydrolytic resistance may be expressed as the extracted Na<NUM>O equivalent in µg per g glass. The extracted Na<NUM>O equivalent in µg per g glass is determined according to ISO <NUM>:<NUM>-<NUM>. It is a measure of the extractability of basic compounds from glass in water at <NUM>.

In one embodiment, the glass has a phase separation factor with regard to its hydrolytic resistance in the range of between <NUM> and <NUM>, or between <NUM> and <NUM>, or between <NUM> and <NUM>, or between <NUM> and <NUM>, or between <NUM> and <NUM>, in particular between <NUM> and <NUM>. In particular, the factor is at least <NUM>, or at least <NUM>, or at least <NUM>, or at least <NUM> or at least <NUM>. Preferably, this factor is close to <NUM>, which corresponds to the case of unchanged hydrolytic resistance after phase separation. In one version, the phase separation factor is up to <NUM>, up to <NUM> or up to <NUM>.

In one embodiment the factor is at least <NUM> and up to <NUM>. In another version, the phase separation factor is at least <NUM> and up to <NUM>.

Due to the glass properties, the UVC-glass covers can be sealed hermetically, for example by the use of laser glass frit sealing. This hermetical sealing is important, since a number of UVGI-applications take place in either aqueous environments (e.g. biofilm treatment or water treatment), humid environments (e.g. sewage systems) and/or environments with elevated gas-pressure or under vacuum. Furthermore, the hermetical sealing allows the final device, e.g. a UVC-LED-lamp, to be autoclaved, so that it can be used in hospitals, in surgery, in laboratories or in any other environment where high hygienic standards are needed.

This is contrary to conventional glasses, quartz and/or fused silica glasses, which do not possess the thermic properties needed for laser frit sealing, and, thus, cannot be sealed hermetically. However, the glasses described herein are suitable to achieve crack free and tight glass frit connections.

The glasses of this invention preferably have a product CTE [°C-<NUM>] x T<NUM> [°C] of at most <NUM>, more preferably at most <NUM> or at most <NUM>. The product may be at least <NUM> or at least <NUM>. It has been shown that these glasses show advantageous properties with regard to fusion stress and melting behavior.

"T<NUM>" is the temperature at which the glass has a viscosity of <NUM><NUM> dPa*s. T<NUM> can be measured by the methods known to the person skilled in the art for determining the viscosity of glass, e.g. according to DIN ISO <NUM>-<NUM>: <NUM>-<NUM>. "T<NUM>" is the temperature at which the glass has a viscosity of <NUM><NUM> dPa*s.

The average linear coefficient α of the thermal expansion (CTE) (at <NUM>; <NUM>, according to ISO <NUM>) is in one embodiment between <NUM> and <NUM> * <NUM>-<NUM> K-<NUM>. The thermal expansion coefficient (CTE) may be less than <NUM> *<NUM>-<NUM> K-<NUM>. It may range from <NUM> to < <NUM> * <NUM>-<NUM> K-<NUM>, more preferably from <NUM> to <NUM> * <NUM>-<NUM> K-<NUM>, more preferably from <NUM> to <NUM> * <NUM>-<NUM> K-<NUM>, still more preferably from <NUM> to <NUM> * <NUM>-<NUM> K-<NUM>. This allows adapting the thermal expansion properties to the overall thermal expansion properties of the UV-device and therefore prevents tensions within the glass cover. In one embodiment, the same or similar CTE is chosen for both the UVC-glass cover as well as the underlying UV-device (e.g. UVC-LED-package).

Preferably, the glass transition temperature is below <NUM>. It may be in a range of from <NUM> to <NUM>, more preferably between <NUM> and <NUM>, in another embodiment in a range of between <NUM> and <NUM>. The processing temperature T<NUM> is the temperature at which the glass viscosity is <NUM><NUM> dPa*s. The processing temperature T<NUM> of the glasses of the present invention may be below <NUM>, in some embodiments below <NUM>. It may be in a range of between <NUM> and <NUM>, more preferably in a range of between <NUM> and <NUM>.

In order that the melting properties, including Tg and T<NUM>, are in the desired range, it may be advantageous to set the ratio of the content B<NUM>O<NUM> to the sum of SiO<NUM> and Al<NUM>O<NUM> (in mol%) in a narrow range. In an advantageous embodiment, this ratio is at least <NUM> and/or at most <NUM>.

Another important property of the glasses is their excellent spatial homogeneity of the refractive index nd of the material. Optionally, a refractive index variation within the glass may correspond to a deformation of the wavefront passing through the glass, according to the following formula: <MAT> wherein Δs is the wavefront deviation, d is the thickness of the glass, Δd is the thickness variation (difference between maximum and minimum thickness) and Δnd is the refractive index variation (difference between maximum and minimum refractive index) in the glass. The invention further includes glass articles having the indicated wavefront deviation.

The wavefront deviation can be calculated according to the formula above. The refractive index nd (λ = <NUM>) and the thickness may be determined at <NUM>. In one embodiment the wavefront deviation is determined over and/or applies to a surface area of <NUM><NUM>. The wavefront deviation may be determined for a thickness of <NUM> of glass, or less; or <NUM> of glass or less. Optionally, the thickness may be at least <NUM>. The wavefront deviation may be less than ± <NUM>, less than ± <NUM>, in further embodiments less than ± <NUM>, less than ± <NUM>, less than ± <NUM>, or less than ± <NUM>. Optionally, the wavefront deviation may be between <NUM> and <NUM>, or between <NUM> and <NUM>, or between <NUM> and <NUM>.

The wavefront deviation may be measured axial, e.g. in the case of glass tubes, as used for example in discharge lamps; or lateral, e.g. in the case of rod sections, as used for lenses in UVC-LEDs.

The wavefront may also be measured by a wavefront sensor. This is a device which measures the wavefront aberration in a coherent signal to describe the optical quality or lack thereof in an optical system. Without being bound to a specific method, a very common method is to use a Shack-Hartmann lenslet array.

Alternative wavefront sensing techniques to the Shack-Hartmann system are mathematical techniques like phase imaging or curvature sensing. These algorithms compute wavefront images from conventional brightfield images at different focal planes without the need for specialized wavefront optics.

The glasses and glass articles according to the present invention may have a low content of wavefront deformations in the glass (striae, bubbles, streaks, etc.). In general, it can be distinguished between the global or long-range homogeneity of refractive index in the material and short-range deviations from glass homogeneity. Striae are spatially short-range variations of the homogeneity in a glass. Short-range variations are variations over a distance of about <NUM> and up to <NUM>, whereas the spatially long range global homogeneity of refractive index covers the complete glass piece.

In some embodiments an ultraviolet ray transmission filter may be used, which filters out certain non-desired UV-wavelengths, e.g. wavelengths below <NUM>, in some embodiments below <NUM>; and/or above <NUM>, in some embodiments above <NUM>.

The glasses for UV-covers according to the present invention may allow the shaping of lenses in order to optically shape the UV-beam, for example for directional focusing of the UV-light to the target.

Any beam angle between <NUM>° and <NUM>° is possible. In some embodiments <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM> to <NUM>° may be used. In other embodiments <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>°, <NUM>° to <NUM>° may be used.

In some embodiments rather broad beam shapes, such as <NUM>°, <NUM>° or even <NUM>°, are useful, for example in cases in which a surface of a certain size or a certain volume or a tube of a certain diameter needs to be decontaminated in one treatment.

In other embodiments narrow beam shapes such as <NUM>°, <NUM>° or even <NUM>°, are useful. For example narrow beam shapes can be used to concentrate the UV-exposure at the target site and avoid non-directional and undesired radiation, which would result in a less efficient energy-to-radiation ratio or exposure of UV-sensitive surfaces to UV-light. One example may be the limited decontamination of defined areas of an eye.

Furthermore, different lens shapes and beam angles may be used to solve complex MRSA-eradication tasks. For example in cases in which UV-sensitive surfaces of different sensitive levels are next to each other and need to be UV-exposed in one treatment.

For example, it may be suitable to treat the skin of a patient in some areas with higher UV-exposure than in neighboring areas, e.g. during wound treatment and/or surgery, where the wound itself is exposed to less UV than the surrounding skin.

The discolure includes also methods for the production of LED-packages with covers made with the inventive UVC-transparent glasses.

An LED package according to the present disclosure may comprise.

Such windows may be flat or having a shape for changing the path of the light (i.e. lens-shape).

As mentioned before, UVC-LEDs may be packaged and sealed in a way (e.g. laser frit sealing) so that they are autoclavable, sterilizable and resistent against fluids. Such UVC-LEDs may be used for sterilization of air and water, surfaces; and for medical/dental applications.

The UVC-LEDs having the UVC-transparent glass described herein possess further advantages in comparison to conventional UVGI-lamps or devices (such as mercury-vapor lamps), for example:.

Traditionally, both low and medium pressure mercury lamps have been utilized in disinfection systems. However, there is a need to replace these light sources with high powered and energy-efficient UV-lights, such as for example UVC-LEDs. The UV-lamps and the UV-devices under this invention are more energy efficient as compared to conventional UVGI-lamps or - devices. This is because the inventive glass may transmit more than <NUM>% of the UV-light at <NUM> and therefore the ratio between energy-input and radiation-output is significantly improved.

This becomes important when these glasses are used as covers of UVC-LED-lamps. If the energy requirement of a conventional mercury-vapor-UV-lamp is set at <NUM>%, the energy necessary to generate the same UV-radiation with the UVC-LEDs described herein is about <NUM> to <NUM>%. In other words, if a conventional UV-lamp uses <NUM> W of energy to emit a certain UV-intensity the devices herein may use only between <NUM> and <NUM> W.

As mentioned before, another advantage of the UVC-transparent glasses described herein are their high thermal conductivity (λw), which may be between <NUM> and <NUM> W * m-<NUM> * K-<NUM> at <NUM>, in other embodiments about <NUM> W * m-<NUM> * K-<NUM>. This superior thermal conductivity increases the lifetime of the device, since excess heat can dissipate easily before harming other parts of the device. This is for example in contrast to quartz-glasses, which normally have a less optimal thermal conductivity.

Thus, in one embodiment, the method according to present invention may include UV-lamps with an energy efficiency index (EEI) of ≤ <NUM> according to the REGULATION (EU) No <NUM>/<NUM> in case of non-directional UV-lamps and an energy efficiency index (EEI) of ≤ <NUM> according to the REGULATION (EU) No <NUM>/<NUM> in case of directional UV-lamps.

The methods described herein may be used for eradication of MRSA from any kind of surface, including UV-sensitive surfaces, UV-sensitive liquid and/or UV-sensitive gas.

Of course the methods described herein may be used also for eradication other UV-sensitive pathogenic organisms, such as viruses (such as for example influenza- or coronaviridae, such as SARS-CoV-<NUM>, especially resistant virus mutations, such as for example SARS-CoV2-D614G), bacteria (including spores), pathological yeasts, mold, and the like.

Potential applications can be selected from the list of uses comprising hand sanitizers (e.g. on private and public toilets), room sanitizers in health care environments, MRSA-eradication in preparation to or during or after surgery, wound treatment, eye treatment, food disinfection (e.g. during food production and/or meat, dairy or vegetable counter in supermarkets), livestock disinfection (especially in cases of intensive animal husbandry, such as for example laying batteries), production of pharmaceutical compounds and/or food production processes, storage facilities and/or disinfection of UV-sensitive surfaces which are often in contact with many different users, for example keyboards, handles, handrails, tooth brushes, hair brushes, ornaments, touch-devices, shaving razors, or kids toys.

The UVC-devices disclosed herein can also be used for a wide range of applications as "analytical instrumentation", for example:.

In another embodiment the UVC-devices disclosed herein may comprise devices for "water disinfection". In that respect UVC LEDs are advantageous as compared to traditional mercury lamps, which require a long warm up time (anywhere from <NUM> seconds to <NUM> minutes) to reach the required germicidal intensity. In addition, frequent on/off cycles can diminish lifetime by <NUM> percent or more.

Consequently, mercury lamps in these applications need to be kept on all day, increasing the frequency of lamp replacement and rising power consumption. By contrast, the instant on-off capability of UVC LEDs enables on-demand disinfection, which reduces power consumption significantly.

Additionally, the frequent on/off-cycles do not diminish LED lifetime, helping lower operating and maintenance costs.

Further uses of the UVC-devices disclosed herein especially in cases of UV-sensitive surfaces, liquids or gases, may comprise:.

Thus, in one embodiment the use of the UV-LED-module of the present disclosure may be selected from the group of water disinfection, analytical instrumentation (HPLC, spectrometers, water monitoring sensors), air purification, air disinfection, surface disinfection (e.g. keyboard disinfection, escalator handrail UV sterilizer), cytometry, molecular identification, protein analysis, biofilm treatment, curing, lithography, vegetable growth, skin cure, germ detection, drug discovery, protein analysis, induction of skin vitamine-D3-production and/or sterilization. Thus, in one aspect the invention pertains to uses of the glass according to the invention as a hermetically sealing lens cap for an UV-LED-module, e.g. for applications selected from the group of water disinfection, analytical instrumentation (HPLC, spectrometers, water monitoring sensors), air purification, air disinfection, surface disinfection (e.g. keyboard disinfection, escalator handrail UV sterilizer), cytometry, molecular identification, protein analysis, biofilm treatment, curing, lithography, vegetable growth, skin cure (psoriasis, vitiligo, itching, neurodermatitis, acne, actinic dermatitis, phototherapy, pityriasis rosea,), germ detection, drug discovery, protein analysis, induction of skin vitamine-D3-production and/or sterilization.

According to the disclosure borosilicate glass comprises the following components (in mol% based on oxides):.

According to the invention borosilicate glass comprises the following components (in mol% based on oxides):.

Wherein "R<NUM>O" refers to the alkali metal oxides Li<NUM>O, Na<NUM>O and K<NUM>O; and "RO" denotes the alkaline earth metal oxides MgO, CaO, BaO and SrO.

The glasses of the present invention may contain SiO<NUM> in a proportion of at least <NUM> mol%, or at least <NUM> mol%. SiO<NUM> contributes to the hydrolytic resistance and transparency of the glass. If the SiO<NUM> content is too high, the melting point of the glass is too high. The temperatures T<NUM> and Tg also rise sharply. Therefore, the content of SiO<NUM> should be limited to a maximum of <NUM> mol%, or to a maximum of <NUM>%.

Preferably the content of SiO<NUM> is at least <NUM> mol%, at least <NUM> mol% or at least <NUM> mol%, at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%. The content can be limited to a maximum of <NUM> mol% or a maximum of <NUM> mol%, or a maximum of <NUM> mol%.

The glasses of the present invention contain Al<NUM>O<NUM> in a maximum proportion of <NUM> mol%. Al<NUM>O<NUM> contributes to the phase separation stability of the glasses, but in larger proportions reduces the acid resistance. Furthermore, Al<NUM>O<NUM> increases the melting temperature and T<NUM>. Thus, the content of this component should be limited to a maximum of <NUM> mol%, or to a maximum of <NUM> mol%, or to a maximum of <NUM> mol%, or to a maximum of <NUM> mol%, or to a maximum of <NUM> mol%, or to a maximum of <NUM> mol%. In some embodiments Al<NUM>O<NUM> is used in a small proportion of at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%, or at least <NUM> mol%. In some embodiments the glass may be free of Al<NUM>O<NUM>.

The glasses of the present invention may contain B<NUM>O<NUM> in a proportion of at least <NUM> mol%. B<NUM>O<NUM> has a beneficial effect on the melting properties of glass, in particular, the melting temperature is lowered and the glass can be fused with other materials at lower temperatures.

However, the amount of B<NUM>O<NUM> should not be too high, otherwise the glasses have a strong tendency to phase separation. In addition, too much B<NUM>O<NUM> has a negative effect on the hydrolytic resistance and the glass tends to have a high evaporation loss during production, resulting in a glass with knots. Thus, B<NUM>O<NUM> should be limited to up to <NUM> mol%, up to <NUM> mol%, or up to <NUM> mol%. The content of B<NUM>O<NUM> can be at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%.

In a preferred design, the ratio of the sum of the contents (in mol%) of B<NUM>O<NUM>, R<NUM>O and RO to the sum of the contents (in mol%) of SiO<NUM> and Al<NUM>O<NUM> is at most <NUM>, in particular at most <NUM>, more preferably at most <NUM>. In one embodiment, this value is at least <NUM>, preferably at least <NUM>, or at least <NUM>. Glasses with the above-mentioned proportion have good properties in terms of hydrolytic resistance and phase separation factor, and they have only a low induced extinction, which has many advantages, especially when used as UV-transparent material.

The glasses of the present invention may contain Li<NUM>O in a proportion of up to <NUM> mol%, or up to <NUM> mol%, or up to <NUM> mol%, or up to <NUM> mol%. Li<NUM>O increases the fusibility of the glasses and results in a beneficial shift of the UV edge to lower wavelengths. However, lithium oxide tends to evaporate, increases the tendency to phase separation and also increases the price of the mixture. In the preferred design, the glass contains only a small amount of Li<NUM>O, e.g. to a maximum of <NUM> mol%, to a maximum of <NUM> mol%, to a maximum of <NUM> mol%, to a maximum of <NUM> mol%, or to a maximum of <NUM> mol%, or the glass is free of Li<NUM>O. In certain embodiments the content of Li<NUM>O is between <NUM> mol% and <NUM> mol%.

The glasses of the invention contain Na<NUM>O in a proportion of up to <NUM> mol%, or up to <NUM> mol%. Na<NUM>O increases the fusibility of the glasses. However, sodium oxide also leads to a reduction in UV transmission and an increase in the coefficient of thermal expansion (CTE). The glass may contain Na<NUM>O in a proportion of at least <NUM> mol%, or at least <NUM> mol%. In one version the content of Na<NUM>O is a maximum of <NUM> mol%, or a maximum of <NUM> mol%. In some embodiments the glass may be free of Na<NUM>O.

The glasses of the present invention contain K<NUM>O in a maximum proportion of <NUM> mol%. K<NUM>O increases the fusibility of the glasses and results in a beneficial shift of the UV edge to lower wavelengths. Its content may be at least <NUM> mol%, or at least <NUM> mol%. However, a potassium oxide content that is too high leads to a glass that has a disturbing effect when used in photomultipliers due to the radiating property of its isotope <NUM>K. Therefore, the content of this component must be limited to a maximum of <NUM> mol%, to a maximum of <NUM> mol%, to a maximum of <NUM> mol%, to a maximum of <NUM> mol%, or a maximum of <NUM> mol%. In some embodiments the glass may be free of K<NUM>O.

In an embodiment of the invention, the ratio of the contents of Na<NUM>O to K<NUM>O in mol% is at least <NUM>, in particular at least <NUM>. In an embodiment of the invention the said ratio is at most <NUM>, in particular at most <NUM>. Both oxides serve to improve the fusibility of the glass. However, if too much Na<NUM>O is used, the UV transmission is reduced. Too much K<NUM>O increases the coefficient of thermal expansion. It was found that the ratio given achieves the best results, i.e. the UV transmission and the coefficient of thermal expansion are in advantageous ranges. In certain embodiments the ratio is between <NUM> and <NUM>.

The amount of R<NUM>O in the glasses of the present invention is preferably not more than <NUM> mol%, not more than <NUM> mol%, or not more than <NUM> mol%. The glasses may contain R<NUM>O in amounts of at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%. Alkali metal oxides increase the fusibility of the glasses, but, as described above, lead to various disadvantages in higher proportions. In certain embodiments the content of R<NUM>O is between <NUM> mol% and <NUM> mol%.

The glasses of the present invention may contain MgO in a proportion of up to <NUM> mol%, up to <NUM> mol%, up to <NUM> mol%, or up to <NUM> mol%. MgO is advantageous for fusibility, but in high proportions it proves to be problematic with regard to the desired UV transmission and the tendency to phase separation. Preferred designs are free of MgO.

The glasses of the present invention may contain CaO in a proportion of up to <NUM> mol%, up to <NUM> mol%, up to <NUM> mol%, or up to <NUM> mol%. CaO is advantageous for fusibility, but in high proportions it proves to be problematic with regard to the desired UV transmission. Preferred forms are free of CaO or contain only little CaO, e.g. at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%.

The glasses of the present invention may contain SrO in a proportion of up to <NUM> mol%, up to <NUM> mol%, or up to <NUM> mol%. SrO is advantageous for fusibility, but in high proportions it proves to be problematic with regard to the desired UV transmission. Preferred designs are free from SrO.

The glasses of the present invention may contain BaO in a proportion of up to <NUM> mol%, or up to <NUM> mol%, or up to <NUM> mol%. BaO leads to an improvement of the hydrolytic resistance. However, a too high barium oxide content leads to phase separation and, thus, to instability of the glass. Preferred embodiments contain BaO in amounts of at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%. In certain embodiments the content of BaO is between <NUM> mol% and <NUM> mol%. In some embodiments the glass may be free of BaO.

It has been shown that the alkaline earth oxides RO have a great influence on the phase separation tendency. In a design form, special attention is therefore paid to the contents of these components and their relationship to one another. Thus, the ratio of BaO in mol% to the sum of the contents of MgO, SrO and CaO in mol% should be at least <NUM>. Preferably, this value is at least <NUM>, or at least <NUM>, or at least <NUM>. In particularly preferred forms, the value is at least <NUM>, or even at least <NUM>. BaO offers the most advantages in terms of phase separation and hydrolytic resistance compared to the other alkaline earth metal oxides. However, the ratio should not exceed <NUM> or <NUM>. In advantageous forms, the glass contains at least small amounts of CaO and BaO and is free of MgO and SrO. In certain embodiments the ratio is between <NUM> and <NUM>.

Advantageous properties are obtained in particular if the ratio of the proportion of CaO in the glass to BaO in mol% is less than <NUM>. In particular, this ratio should be less than <NUM> or less than <NUM>. In some embodiments the ratios are even lower, in particular less than <NUM>, or less than <NUM>, and in a preferred design this ratio is at least <NUM>. In certain embodiments the ratio is between <NUM> and <NUM>.

In one version, the glass has a mol% ratio of B<NUM>O<NUM> to BaO of at least <NUM> and at most <NUM>. Preferably, the ratio is at least <NUM>, or at least <NUM> and, in a preferred design, the said ratio is limited to a maximum of <NUM>, or of <NUM>, or of <NUM>. In another embodiment, the ratio may be limited to a maximum of <NUM> or <NUM>. In particular, the ratio is not less than <NUM> and not more than <NUM>, or in another embodiment not less than <NUM> and not more than <NUM>; in certain embodiments the ratio is between <NUM> and <NUM>. In one other embodiment the ratio is between <NUM> and <NUM>. Glasses with the above ratios show good properties in terms of hydrolytic resistance and phase separation factor, as well as low induced absorbance.

The proportion of RO in the glasses of the present invention can be at least <NUM> mol%. Alkaline earth metal oxides are advantageous for fusibility, but in high proportions they prove to be problematic with regard to the desired UV transmission. In one version, the glass contains a maximum of <NUM> mol% RO. In one embodiment the proportion of RO is between <NUM> and <NUM> mol%.

The sum of the contents in mol% of alkaline earth metal oxides and alkali metal oxides, RO+R<NUM>O, can be limited to a maximum of <NUM> mol%. Advantageous designs can contain these components in quantities of maximum <NUM> mol%. Preferably the content of these oxides is at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%. In one embodiment the RO+R<NUM>O-proportion is between <NUM> and <NUM> mol%. These components increase the phase separation tendency and reduce the hydrolytic resistance of the glasses in too high proportions.

The ratio of the contents in mol% of B<NUM>O<NUM> to the sum of the contents of R<NUM>O and RO in mol% may be at least <NUM>, at least <NUM>, or at least <NUM>. The ratio can be limited to a maximum of <NUM>, a maximum of <NUM>, or a maximum of <NUM>. In one embodiment the B<NUM>O<NUM>/(RO+R<NUM>O)-proportion is between <NUM> and <NUM>. Alkali or alkaline earth borates can form during glass phase separation, if too much alkali or alkaline earth oxide is present in relation to B<NUM>O<NUM>. It has been proven to be advantageous to adjust the above ratio.

To ensure that the melting properties, including Tg and T<NUM>, are within the desired range, it may be advantageous to set the ratio of the content of B<NUM>O<NUM> to the sum of the contents of SiO<NUM> and Al<NUM>O<NUM> in mol% within a narrow range. In an advantageous design, this ratio is at least <NUM> and/or at most <NUM>. In one embodiment the B<NUM>O<NUM>/(SiO<NUM> + Al<NUM>O<NUM>)-ratio is between <NUM> and <NUM>.

The ratio of the proportions in mol% of the sum of the alkali metal oxides R<NUM>O to the sum of the alkaline earth metal oxides RO is preferably ><NUM>, in particular ><NUM> or ><NUM>. In the design forms, this ratio is at most <NUM>, at most <NUM> or at most <NUM>. In one embodiment the ratio is between <NUM> and <NUM>.

The glasses of the present invention may contain F- in a content of <NUM> to <NUM> mol%. Preferably the content of F- is at most <NUM> mol%. In a design form, at least <NUM> mol%, or at least <NUM> mol% of this component is used. Component F- improves the fusibility of the glass and influences the UV edge towards smaller wavelengths.

The glasses of the present invention may contain Cl- in a content of less than <NUM> mol%, especially less than <NUM> mol%, or less than <NUM> mol%. Suitable lower limits are <NUM> mol%, or <NUM> mol%.

The glasses of the present invention may contain ZnO in a content of less than <NUM> mol%, especially less than <NUM> mol%, or less than <NUM> mol%. Suitable lower limits are <NUM> mol%, or <NUM> mol%. In some embodiments the glass may be free of ZnO.

The glasses of the present invention may contain ZrO<NUM> in a content of less than <NUM> mol%, less than <NUM> mol%, or especially less than <NUM> mol%. Suitable lower limits are <NUM> mol%, or <NUM> mol%. In some embodiments the glass may be free of ZrO<NUM>.

The glasses of the present invention may contain SnO<NUM> in a content of less than <NUM> mol%, especially less than <NUM> mol%, or less than <NUM> mol%. Suitable lower limits are <NUM> mol%, or <NUM> mol%. In some embodiments the glass may be free of SnO<NUM>.

When this description states that the glass is free of a component or does not contain a certain component, it means that this component may at most be present as an impurity. This means that it is not added in significant quantities. Non-significant quantities are quantities of less than <NUM> ppm, preferably less than <NUM> ppm, preferably less than <NUM> ppm and most preferably less than <NUM> ppm.

In one embodiment, the glass has less than <NUM> ppm Fe<NUM>O<NUM>, in particular less than <NUM> ppm or less than <NUM> ppm. In one embodiment, the glass has less than <NUM> ppm TiO<NUM>, in particular less than <NUM> ppm or less than <NUM> ppm. In one embodiment, the glass has less than <NUM> ppm arsenic, in particular less than <NUM> ppm or less than <NUM> ppm. Preference is given to glass containing less than <NUM> ppm antimony, less than <NUM> ppm antimony, or less than <NUM> ppm antimony. Besides the negative effects on UV-transmission and solarization, especially arsenic and antimony are toxic and dangerous to the environment and should be avoided.

In a particularly preferred design, borosilicate glass includes the following components (in mol% on oxide basis):.

In another particularly preferred form, the glass includes the following components in mol%:.

In yet another particularly preferred form, the glass includes the following components in mol%:.

The glass article can be produced by drawing processes known for glass tubes and rods. Depending on the desired shape, the person skilled in the art will choose a suitable manufacturing process, e.g. ingot casting for bars, floating or down draw for producing panes. Preferably, the cooling of the glass in the process is adjusted so that the desired properties are achieved.

In one embodiment, the glass article is produced using the Danner or the Vello method. In the Vello method, the glass melt flows vertically downwards (in the direction of the gravitational force) through a shaping tool made of an outlet ring and a needle. The shaping tool forms a negative form (matrix) of the generated cross-section of the glass tube or the glass rod. In the manufacture of glass tubes, a needle is arranged as a shaping part in the center of the shaping tool.

The difference between the Vello and the down draw method is first of all that the glass melt in the Vello method is deflected horizontally after it leaves the forming tool and, secondly, in the fact that the needle has a passage in the Vello method, through which blown air flows. As with the Danner method, the blown air ensures that the resulting glass tube does not collapse. In the down draw method, the solidified glass melt is separated without prior redirection. Since there is no redirection, one can also refrain from the use of blown air during the production of glass tubes.

In an embodiment, the disclosure relates to a glass article made of the glass disclosed herein.

The thickness of the glass article, in particular the wall thickness in the case of a glass tube, can be at least <NUM> or at least <NUM>. The thickness can be limited to up to <NUM> or up to <NUM>. The outside diameter of the glass article, e.g. the outside diameter of a glass tube or glass rod, can be up to <NUM>, up to <NUM>, or up to <NUM>. The outside diameter can in particular be at least <NUM>, at least <NUM>, or at least <NUM>. In one embodiment, the article has a thickness that is at least <NUM> and/or at most <NUM>. Optionally, the thickness is at least <NUM>, at least <NUM>, or at least <NUM>. The thickness may be limited to a maximum of <NUM>, up to <NUM>, up to <NUM>, or up to <NUM>. In one embodiment, the article has a length and a width, in particular the length being greater than the width. The length may be at least <NUM>, at least <NUM> or at least <NUM>. Optionally, it is at most <NUM>, at most <NUM>, at most <NUM> or at most <NUM>. Preferably, the length is from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>. The width may be at least <NUM>, at least <NUM>, or at least <NUM>. Optionally, the width is at most <NUM>, at most <NUM> or at most <NUM>. Preferably, the width is from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>.

Optionally, the manufacturing process comprises the step of chemical and/or thermal tempering of the glass article. The "tempering" is also referred to as "hardening" or "toughening". Preferably, the glass article is toughened on at least one surface, in particular thermally and/or chemically toughened. For example, it is possible to chemically temper glass articles by ion exchange. In this process, small alkali ions in the article are usually replaced by larger alkali ions. Often, the smaller sodium is replaced by potassium. However, it is also possible that the very small lithium is replaced by sodium and/or potassium. Optionally, it is possible that alkali ions are replaced by silver ions. Another possibility is that alkaline earth ions are exchanged for each other according to the same principle as the alkali ions. Preferably, the ion exchange takes place in a bath of molten salt between the article surface and the salt bath. Pure molten salt, for example molten KNO<NUM>, can be used for the exchange. However, salt mixtures or mixtures of salts with other components can also be used. The mechanical resistance of an article can further be increased if a selectively adjusted compressive stress profile is built up within the article. This can be achieved by mono- or multistage ion exchange processes.

By replacing small ions with large ions or by thermal tempering, a compressive stress is created in the corresponding zone, which drops from the surface of the glass article towards the center. The maximum compressive stress is just below the glass surface and is also referred to as CS (compressive stress). CS is a stress and is expressed in units of MPa. The depth of the compressive stress layer is abbreviated as "DoL" and is given in the unit µm. Preferably, CS and DoL are measured using the FSM-60LE apparatus from Orihara.

In one embodiment, CS is greater than <NUM> MPa. Further preferably, CS is at least <NUM> MPa, at least <NUM> MPa, or at least <NUM> MPa. More preferably, CS is at most <NUM>,<NUM> MPa, at most <NUM> MPa, at most <NUM> MPa, or at most <NUM> MPa. Preferably, CS is in a range from ><NUM> MPa to <NUM>,<NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, or from <NUM> MPa to <NUM> MPa.

In one embodiment, the glass article is thermally toughened. Thermal toughening is typically achieved by rapid cooling of the hot glass surface. Thermal toughening has the advantage that the compressive stress layer can be formed deeper (larger DoL) than with chemical toughening. This makes the glasses less susceptible to scratching, since the compressive stress layer cannot be penetrated as easily with a scratch as with a thinner compressive stress layer.

The glasses or glass articles can, for example, be subjected to a thermal tempering process after a melting, shaping, annealing/cooling process and cold post-processing steps. In this process, glass bodies (e.g. a previously described glass article or a preliminary product), for example flat glass, are preferably fed horizontally or suspended into a device and rapidly heated to a temperature up to a maximum of <NUM> above the transformation temperature TG. The surfaces of the glass body are then rapidly cooled, for example by blowing cold air through a nozzle system. As a result of the rapid cooling of the glass surfaces, they are frozen in an expanded network, while the interior of the glass body cools slowly and has time to contract more. This creates a compressive stress in the surface layer and a tensile stress in the interior. The amount of compressive stress depends on various glass parameters such as CTEglass (average linear coefficient of thermal expansion below Tg), CTEliquid (average linear coefficient of thermal expansion above Tg), strain point, softening point, Young's modulus and also on the amount of heat transfer between the cooling medium and the glass surface as well as the thickness of the glass bodies.

Preferably, a compressive stress of at least <NUM> MPa is generated. As a result, the flexural strength of the glass bodies can be doubled to tripled compared to non-toughened glass. In an embodiment, the glass is heated to a temperature of <NUM> to <NUM> and tempered fast in as stream of cold air. Optionally, the blowing pressure may be from <NUM> to <NUM> kPa. With the glasses or glass articles described herein, values of compressive stress of <NUM> to <NUM> MPa, in particular <NUM> to <NUM> MPa, for example, are achieved on commercially available systems.

In one embodiment, the glass article has a compressive stress layer with a compressive stress of at least <NUM> MPa, in particular at least <NUM> MPa, at least <NUM> MPa or at least <NUM> MPa. The glass article may have a compressive stress layer on one, two or all of its surfaces. The compressive stress of the compressive stress layer may be limited to at most <NUM> MPa, at most <NUM> MPa, at most <NUM> MPa or at most <NUM> MPa. These compressive stress values may be present, in particular, in thermally toughened glass articles.

In one embodiment, the depth of the compressive stress layer of the glass article is at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>. In certain embodiments, this layer may even be at least <NUM>, at least <NUM>, or at least <NUM>. Optionally, the DoL is limited to at most <NUM>,<NUM>, at most <NUM>,<NUM>, at most <NUM>,<NUM>, or at most <NUM>,<NUM>. In particular, the DoL can be from <NUM> to <NUM>,<NUM>, from <NUM> to <NUM>,<NUM>, or from <NUM> to <NUM>,<NUM>. In one embodiment, the glass article is thermally toughened with a DoL of at least <NUM>, at least <NUM> or at least <NUM>. Optionally, the DoL may be at most <NUM>,<NUM>, at most <NUM>,<NUM>, or at most <NUM>,<NUM>. In one embodiment, the DoL is from <NUM> to <NUM>,<NUM>, from <NUM> to <NUM>,<NUM>, or from <NUM> to <NUM>,<NUM>.

The present invention relates to a glass that is resistant in several respects. Particularly resistant glass is especially useful where the glass is exposed to special requirements. This is the case, for example, in extreme environments. Extreme environments are in particular areas of application in which special resistance, durability and safety are required, e.g. areas requiring explosion protection.

In one embodiment, the invention relates to a glass article with special suitability for use in extreme environments. The article may be a sheet, disc, tube, rod, ingot or block. In preferred embodiments, the article is in the form of a sheet or a disc.

The glass article consists of a glass having a transmission throughout the wavelength range of from <NUM> to <NUM> of at least <NUM>% (measured at a thickness of <NUM>), wherein the glass is a borosilicate glass having a total platinum content of not more than <NUM> ppm, and a hydrolytic resistance characterized by an extracted Na<NUM>O equivalent in µg per g glass determined according to ISO <NUM> of not more than <NUM>µg/g, optionally wherein the glass article has a thickness of at least <NUM>, in particular at least <NUM> and/or up to <NUM>.

In extreme environments, it may be useful to provide a certain minimum thickness for the glass article, since thicker glasses are mechanically more stable than thinner glasses. However, thicker glass absorbs a greater portion of the UV radiation entering the glass, resulting in the generation of heat. In environments with highly flammable materials, high heat generation can be problematic. A glass article with low induced extinction at <NUM> and/or <NUM> offers the advantage that transmission remains high for the wavelengths under consideration, even after extended use, and extreme heat generation is avoided.

According to the invention, the glass article can also be used in a UV lamp for disinfecting surfaces in extreme environments. In one embodiment, the glass article is used in a UV lamp (particularly as a cover) that is used to disinfect a site of action. The site of action may be an object that is touched by many people, for example a handle, in particular a door handle. The UV lamp can, for example, be aligned in such a way that it applies UV radiation to the site of action. In this case, a certain proximity to the site of action cannot be avoided. Accordingly, there is a risk here that the glass article will be damaged by impacts. This results in a need for mechanical resistance. The mechanical resistance can be improved by a large thickness of the glass article, which, however, reduces the transmission of the article and greatly increases the heating of the glass during operation of the UV lamp. Excessive heating should be avoided, which in turn is positively influenced by very good transmission and low induced extinction. Excessively high temperatures impair safety due to the risk of user burns or explosions. In principle, the risk of burns can be reduced by greater distance, but this must be compensated with greater radiation intensity with the disadvantage again of stronger heat generation.

The disclosure also relates to a UV lamp and the use of the glass article in a UV lamp for disinfection, in particular in extreme environments, in particular for disinfecting sites of action, e.g. those touched by many people. It has proven advantageous to maintain a minimum distance between the surface to be disinfected and the glass article of <NUM>, in particular <NUM> or <NUM>. When using the glass article described herein, a power density of at least <NUM> mW/cm<NUM>, at least <NUM> mW/cm<NUM>, at least <NUM> mW/cm<NUM>, at least <NUM> mW/cm<NUM> or at least <NUM> mW/cm<NUM> can be set at the site of action. The site of action is the surface to be disinfected. Optionally, the power density is at most <NUM> mW/cm<NUM>, at most <NUM> mW/cm<NUM> or at most <NUM> mW/cm<NUM>. In particular, the power density is the power that can be measured at the site of action as UV radiation, in particular UV-C radiation, mediated by the UV lamp. Preferably, the site of action is periodically disinfected. This means that the site of action is not irradiated continuously, but only intermittently. For example, an irradiation interval can be triggered by touch, presence or actuation by the user. For example, an irradiation interval may be at least <NUM> second, at least <NUM> seconds, at least <NUM> seconds, or at least <NUM> seconds. Optionally, an irradiation interval lasts at most <NUM> minutes, at most <NUM> minutes, at most <NUM> minutes, or at most <NUM> minute.

In one embodiment, the UV lamp and/or the glass article has a heat-optimized structure, wherein the thickness of the glass article and the UV transmission of the glass article are chosen in such a way that when a site of action <NUM> away from the glass article (disposed on the opposite side of the article with respect to the light source) is irradiated with a medium pressure mercury lamp at <NUM> W/cm and an arc length of <NUM> (e.g. Philips HOK <NUM>/<NUM>) at a UVC power density of <NUM>,<NUM> mW/cm<NUM> for a duration of <NUM> seconds at an ambient temperature of <NUM>, no temperature at the surface of the glass article facing the site of action exceeds <NUM>. In one embodiment, the radiation passes perpendicularly through the glass article, i.e., the light enters the glass article substantially perpendicular to the surface facing the light source and/or the light exits the glass article substantially perpendicular to the surface of the glass article facing the site of action. In particular, no temperature exceeds a value of <NUM>, <NUM> or <NUM>. In one embodiment, said temperature limits are not exceeded even after <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds, <NUM> seconds or <NUM> seconds of irradiation. The property describes how strongly the glass article heats up when irradiated vertically with commonly used UV light sources. It is achieved that a UV lamp with a lamp cover made of the glass article does not become dangerously hot. UVC power density refers to the power density imparted by radiation in the UVC range (<NUM> to <NUM>). Medium-pressure mercury lamps also emit light at other wavelengths, which are not taken into account here when considering UVC power density. The measurement is performed under ambient atmosphere. For clarification: the described property does not limit the UV lamp or the application of the glass article to medium-pressure mercury lamps.

In one embodiment, the glass article meets the requirements for the fracture pattern according to DIN EN <NUM>-<NUM>:<NUM>-<NUM>. A whole article or a part of an article can be examined; in deviation from the specified standard, the article can be smaller than indicated there, as long as the area to be considered is exceeded. The area to be considered for the breakage pattern can be in particular <NUM> × <NUM> or <NUM> × <NUM>. In one embodiment, the glass article breaks into not less than <NUM> pieces, in particular not less than <NUM> pieces or not less than <NUM> pieces, under the above conditions. It is advantageous for the article to break into many pieces, since in the event of breakage the risk of injury is low if the pieces are small.

The fracture pattern can be influenced, for example, by the choice of glass composition, cooling condition (thermal shrinkage), by adjusting stresses in the glass and/or by tempering the article.

In one embodiment, the invention relates to a glass article consisting of a glass having a transmission throughout the wavelength range of from <NUM> to <NUM> of at least <NUM>% (measured at a thickness of <NUM>), wherein the glass is a borosilicate glass having a total platinum content of not more than <NUM> ppm, and a hydrolytic resistance characterized by an extracted Na<NUM>O equivalent in µg per g glass determined according to ISO <NUM> of not more than <NUM>µg/g, further wherein the glass article has a thickness of at least <NUM>, in particular at least <NUM> and/or up to <NUM>, further wherein the article has a compressive stress on at least one surface of at least <NUM> MPa and a fracture pattern characterized by fracture of an area of <NUM> × <NUM> into not less than <NUM> pieces determined according to DIN EN <NUM>-<NUM>.

All glasses were melted under reducing conditions in the quartz glass crucible and homogenized with a quartz glass stirrer. All melts were placed in the cooling furnace at <NUM> and cooled to room temperature at a rate of <NUM>/h.

The melts "glass No. <NUM>" was melted at <NUM>° C, refined at <NUM>° C for <NUM>, then stirred at the same temperature for <NUM>, and then left to stand for <NUM> at <NUM>° C, so that the glass was as bubble-free as possible.

After casting, the Pt-free variant ("Glass No. <NUM>") resulted in clear glass cast blocks.

In addition to a chemical analysis of the glasses, the transmission curves of the glasses were recorded at at least two different points on the cast blocks. In order to be able to calculate the transmission curves for the same sample thickness, the refractive index was also determined as a function of the wavelength.

The following table shows an exemplary glass in accordance with this disclosure in mol%.

Two "comparative glasses" of the same composition as "Glass No. <NUM>" were produced comprising:.

The UV-transmission of Glass No. <NUM> was tested at different thicknesses and wavelengths. At a thickness of <NUM> the following transmission was measured:.

At a thickness of <NUM> the following transmission was measured:.

Glass No. <NUM> was then compared to comparative glasses C1 and C2, with a Pt-contamination of <NUM> and <NUM> ppm, respectively.

The transmission at <NUM> was reduced from <NUM>-<NUM>% to about <NUM>% for glass C1 and to about <NUM>-<NUM>% for glass C2, as compared to glass No. <NUM>, showing the high influence of Pt-contamination, as well as an impact on the transmission by other contaminations such as iron and titanium.

The UVC-transparent glass No. <NUM> was used to produce a UVC-LED-lamp, by using the glass as cover in the LED-package. The LED package had a package size of <NUM> × <NUM>.

Furthermore, a UVC-transparent encapsulation material was used to further protect and cover the LED. Such encapsulation material may be copolymers of methyl methacrylate and acyloximino methacrylate ester. In this example poly-(methyl methacrylate-co-<NUM>-methacryloyl-oximino-<NUM>-butanone) was used.

Because of the advantageous thermic properties, the glass cover could be frit sealed with a laser to the package surface in order make the UVC-LED-lamp autoclavable even at elevated gas-pressures and to be useable in environments which comprise elevated humidity or gas-pressures.

The LED-lamp was compared with conventional LED-lamps. It could be shown that the LEDs made using the invention are about <NUM>% more energy efficient than conventional UV-lamps.

A surface with MRSA-CFUs (colony forming units) were irradiated by UVC-LED-lamps of the present invention. <NUM>,<NUM>µW·s/cm<NUM> of UVC at <NUM> were applied for <NUM> minutes. After a UVC-treatment for <NUM> minutes less than <NUM>% of MRSA - CFUs could be identified.

Thus, glass No. <NUM> is a glass with high UV-transmission and a hydrolytic resistance characterized by an equivalent amount of Na<NUM>O extracted in water at <NUM> of not more than <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and/or <NUM>µg/g.

Further inventive glass-compositions with high UV-transmission and a hydrolytic resistance are depicted in the following table. The content of the components is listed in mol%. Further physical properties of the glasses are listed as well.

The following table shows the solarisation resistance (induced absorbance) after exposure to a deuterium lamp for <NUM> and <NUM>, respectively. The transmission was measured at a glass-thickness of <NUM> to <NUM>.

The following table shows rounded transmission-values for some glasses after exposure to a deuterium lamp after <NUM> and <NUM>, respectively.

Claim 1:
Method for eradicating Methicillin-resistant Staphylococcus aureus (MRSA), the method comprising exposing the MRSA to germicidal UV light within the wavelength range of from <NUM> to <NUM>, wherein the UV light is irradiated by a UV lamp having a lamp cover made of a borosilicate glass having a transmission throughout the wavelength range of from <NUM> to <NUM> of at least <NUM>% measured at a thickness of <NUM> and having a total platinum content of less than <NUM> ppm and a hydrolytic resistance characterized by an extracted Na<NUM>O equivalent in µg per g glass determined according to ISO <NUM> of not more than <NUM>µg/g;
wherein the glass comprises the following components in the indicated amounts (in mol%):

<TAB>

wherein "R<NUM>O" refers to the alkali metal oxides Li<NUM>O, Na<NUM>O and K<NUM>O; and "RO" denotes the alkaline earth metal oxides MgO, CaO, BaO and SrO;
and wherein the sum of the contents of Pt, TiO<NUM> and Fe<NUM>O<NUM> is below <NUM> ppm.