bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase Evolution and Dielectric Properties of (Mg0.95M0.052+)Ti2O5 (M2+=Co, Ni, and Zn) Ceramics at Microwave Frequencies
Authors: Huang Cheng‐Liang , Shen Chun‐Hsu
Published: February 2009

Being the second phase in the (Mg0.95M0.052+)Ti2O5 (M2+=Co, Ni, and Zn) ceramics, the sintering behavior and microwave dielectric properties of specimens using (Mg0.95M0.052+)Ti2O5 were investigated. (Mg0.95M0.052+)Ti2O5 solid solutions were detected throughout the entire experiment. Lattice parameters were also measured for specimens with different M2+ to confirm the formation of solid solutions. The sintering temperature of (Mg0.95Co0.05)Ti2O5 was 25°C lower than those of the others. The (Mg0.95M0.052+)Ti2O5 ceramics, in this study, acquired the following microwave dielectric properties: ɛr of 16–18.5, Q×f of 28 000–68 000 GHz, and τf of −38∼−47 ppm/°C. Compatible ɛr and τf values were obtained in comparison with that of (Mg0.95M0.052+)TiO3 ceramics. However, it showed a much lower Q×f, indicating that the formation of (Mg0.95M0.052+)Ti2O5 in the (Mg0.95M0.052+)TiO3 ceramics would cause a drastic reduction in the Q×f value.
Metal Oxides for Dye‐Sensitized Solar Cells
Authors: Jose Rajan , Thavasi Velmurugan , Ramakrishna Seeram
Published: February 2009

The incessant demand for energy forces us to seek it from sustainable resources; and concerns on environment demands that resources should be clean as well. Metal oxide semiconductors, which are stable and environment friendly materials, are used in photovoltaics either as photoelectrode in dye solar cells (DSCs) or to build metal oxide p–n junctions. Progress made in utilization of metal oxides for photoelectrode in DSC is reviewed in this article. Basic operational principle and factors that control the photoconversion efficiency of DSC are briefly outlined. The d‐block binary metal oxides viz. TiO2, ZnO, and Nb2O5 are the best candidates as photoelectrode due to the dissimilarity in orbitals constituting their conduction band and valence band. This dissimilarity decreases the probability of charge recombination and enhances the carrier lifetime in these materials. Ternary metal oxide such as Zn2SnO4 could also be a promising material for photovoltaic application. Various morphologies such as nanoparticles, nanowires, nanotubes, and nanofibers have been explored to enhance the energy conversion efficiency of DSCs. The TiO2 served as a model system to study the properties and factors that control the photoconversion efficiency of DSCs; therefore, such discussion is limited to TiO2 in this article. The electron transport occurs through nanocrystalline TiO2 through trapping and detrapping events; however, exact nature of these trap states are not thoroughly quantified. Research efforts are required not only to quantify the trap states in mesoporous metal oxides but new mesoporous architectures also to increase the conversion efficiency of metal oxide‐based photovoltaics.
Synthesis, Rietveld Analysis, and Solid State Nuclear Magnetic Resonance of X2‐Sc2SiO5
Authors: Alba María D. , Chain Pablo , González‐Carrascosa Triana
Published: February 2009

Compounds containing rare earths are of increasing technological interest especially because of their unique mechanical, magnetic, electrical, and optical properties. Among them, rare earth oxyorthosilicates are attractive scintillators for γ‐ and X‐ray spectroscopy and detection. However, there are many structural aspects of those compounds that are not clear. In this research, the structure parameters for Sc2Si2O5, X2‐polymorph, have been refined from powder X‐ray diffraction (XRD) data and the29Si MAS NMR spectrum is reported for the first time. X2‐Sc2SiO5polymorph was synthesized by the sol–gel method and characterized by XRD and29Si MAS NMR. The XRD pattern was indexed in a monoclinic unit cell with space groupI2/c; the resulting unit cell parameters werea=9.9674(2) Å,b=6.4264(9) Å,c=12.0636(2) Å, and β=103.938(1)°. The29Si MAS NMR spectrum showed a unique signal at −79.5 ppm, compatible with the unique Si crystallographic site in the unit cell. Finally, the band valence method has been applied to the calculation of a “shift parameter,” which is correlated with the NMR chemical shift.
Hierarchically Porous Ceramics from Diatomite Powders by Pulsed Current Processing
Authors: Akhtar Farid , Vasiliev Petr O. , Bergström Lennart
Published: February 2009

Hierarchically porous ceramic monoliths have been fabricated by pulsed current processing (PCP) of diatomite powders. The partial sintering behavior of the porous diatomite powders during PCP or spark plasma sintering was evaluated at temperatures between 600° and 850°C. Scanning electron microscopy and mercury porosimetry measurements showed that the PCP method was able to bond the diatomite powder together into relatively strong monoliths without significantly destroying the internal pores of the diatomite powder at a temperature range of 700°–750°C. Little fusion at the particle contact points occurred at temperatures below 650°C while the powder showed partial melting and collapse of both the interparticle pores and the internal structure at temperatures above 800°C.
The Effect of Deposition Temperature and Postanneal on the Bi3.63Pr0.3Ti3O12 thin Films Prepared by RF‐Magnetron Sputtering Method
Authors: Wu Yunyi , Zhang Duanming , Yu Jun , Wang Yunbo
Published: February 2009

Praseodymium doped Bi4Ti3O12 (BTO) thin films with composition Bi3.63Pr0.3Ti3O12 (BPT) were successfully prepared on Pt/Ti/SiO2/Si substrates by RF‐magnetron sputtering method at substrate temperatures ranging between 500° and 750°C. The structural phase and orientation of the deposited films were investigated in order to understand the effect of the deposition temperature on the properties of the BPT films. As the substrate temperature was increased to 700°C, the films started showing a tendency of assuming a c‐axis preferred orientation. At lower temperatures, however, polycrystalline films were formed. The Pt/BPT/Pt capacitor showed an interesting dependence of the remnant polarization (2Pr) as well as dc leakage current values on the growth temperature. The film deposited at 650°C showed the largest 2Pr of 29.6 μC/cm2. With the increase of deposited temperature, the leakage current densities of films decreased at the same applied field and the film deposited at 750°C exhibited the best leakage current characteristics. In addition, the ferroelectric fatigue and Raman measurements were carried out on the as‐prepared, postannealed in air and postannealed in oxygen BPT films. It was revealed that the BPT film postannealed in air exhibited the weakest fatigue‐resistance characteristics and highest frequency shifted Raman vibration modes, indicating the highest oxygen vacancy concentration in this film.
Residual Stress Analysis of Multilayer Environmental Barrier Coatings
Authors: Harder B. J. , Almer J. D. , Weyant C. M. , Lee K. N. , Faber K. T.
Published: February 2009

Silicon‐based ceramics (SiC, Si3N4) are promising materials systems for high‐temperature structural applications in gas turbine engines. However, the silica layer that forms on these materials is susceptible to attack from water vapor present in combustion environments. To protect against this degradation, environmental barrier coatings (EBCs) have been developed to shield the underlying substrate and prevent degradation. Here we report on elastic and thermal properties, as well as internal stresses of candidate multilayer coatings, as measuredin situusing microfocused high‐energy X‐rays in a transmission diffraction geometry. Doped aluminosilicate coatings were investigated for their stability on a SiC/SiC melt‐infiltrated substrate. The coatings consisted of a Ba1−xSrxAl2Si2O8topcoat with a mullite or mullite+SrAl2Si2O8interlayer, and a silicon bond coat. A numerical model was used to compare the stress results with an ideal coating system. Experiments were carried out on as‐sprayed and heat‐treated samples in order to analyze the strain and phase evolution as a function of multilayer depth and temperature. The phase transformation of the topcoat promoted healing of cracks in the EBC and reduced stresses in the underlying layers and the addition of SAS to the interlayer reduced stresses in thermally cycled coatings, but did not stop cracks from forming.
Analysis of Grinding Rate Constant on a Stirred Ball Mill Using Discrete Element Method Simulation
Authors: Kim Seongsoo , Chung Hanshik , Choi Heekyu
Published: February 2009

The results of discrete element method simulation were compared with actual grinding experimental results. The grinding rate constant K can be expressed as K=a exp(bn), where n is the rotation speed. To investigate the correlation between K and the simulation results, a new factor, the calculated force, was defined as Fcal=average force acting on a ball coordination number. K could then be expressed as K=a′Fcal+b′ and is thus one‐dimensionally proportional to FcalK was found to be correlated with the forces acting on a ball and its contact points. Experimental results confirmed that Fcal is suitable for use as a factor for expression of K.
Effect of Polyethylene Glycol Content on the Optical Properties of Ba0.9Sr0.1TiO3 Multilayers
Authors: Shang Jinglin , Hu Gujin , Zhang Ting , Sun Yan , Wu Jie , Chu Junhao , Dai Ning
Published: February 2009

Quasiperiodic Ba0.9Sr0.1TiO3 (BST) multilayers have been fabricated on SrTiO3 substrates by using chemical solutions containing polyethylene glycol (PEG), and effect of PEG content on optical properties of the BST multilayers have been investigated. Each multilayer with a single perovskite phase displays a layered structure consisting of dense and porous BST layers. It is found that the central wavelength of the reflection‐band for BST multilayers shifts to longer wavelength with increasing the PEG concentration within a given polymer amount range. With the same numbers of period and processing condition, the BST multilayers derived from chemical solutions containing PEG additives with a relative molar amount of 0.5, exhibit the highest optical reflectivities.
Natural Abundance 43Ca NMR Spectroscopy of Tobermorite and Jennite: Model Compounds for C–S–H
Authors: Bowers Geoffrey M. , Kirkpatrick R. James
Published: February 2009

There are few effective methods for characterizing the molecular scale structural environments of Ca2+ in hydrated cements, which has limited our ability to understand the structure of, for example, Ca–silicate hydrate (C–S–H). 43Ca nuclear magnetic resonance (NMR) spectroscopy has long been considered too insensitive to provide useful data in this regard, but 43Ca magic angle spinning (MAS) NMR spectra reported here for synthetic tobermorite and jennite with naturally abundant levels of 43Ca demonstrate that this is a viable approach. We show that spectra with useful signal/noise ratios can be obtained in a reasonable acquisition period (∼2 days) using an H0 field strength of 21.1 T, 5 mm rotors spinning at a frequency of 5 kHz, and a double frequency sweep preparatory pulse sequence. Tobermorite and jennite produce relatively broad resonances due to their complex structures and structural disorder, however, the chemical shift differences between six‐coordinate 43Ca in jennite and seven‐coordinate 43Ca in 11 Å tobermorite are large enough that the signals are entirely resolved at this field. These data suggest that signal from ideal tobermorite‐like and jennite‐like sites in cement C–S–H can most likely be distinguished by 43Ca NMR and that this method will be a powerful approach for studying cement‐based ceramic materials in the coming decade.
Generation of Emission Centers for Broadband NIR Luminescence in Bismuthate Glass by Femtosecond Laser Irradiation
Authors: Peng Mingying , Zhao Quanzhong , Qiu Jianrong , Wondraczek Lothar
Published: February 2009

Bismuth‐doped glasses have recently received significant interest as potential material for ultrabroadband optical amplification in the telecommunication spectral bands, as well as as gain material for fiber lasers. However, the nature of the active centers that are responsible for the observed near‐infrared (NIR) luminescence is still highly debated. In order to probe the mechanism that leads to NIR emission in bismuth‐containing glasses, femtosecond (fs) laser irradiation was used. It is shown that local absorption properties in the visible spectral range can be altered in initially transparent bismuthate glasses after fs laser irradiation. Induced absorption centers exhibit the well‐known broadband optical emission peaking at ∼1250 nm when excited with a 785 nm diode laser. Absorption and emission intensities increase with increasing average pulse energy. These observations are interpreted as a photo‐induced reduction reaction of Bi3+ to Bi+ species, while the previously discussed formation of Bi‐clusters by ion diffusion is excluded due to the very short interaction time that results from the use of fs laser. Bi+ species are, therefore, proposed as the major origin of NIR emission from Bi‐doped glasses.
Structural and Optical Characteristics of Crystalline Silicon Carbide Nanoparticles Synthesized by Carbothermal Reduction
Authors: Kim Kwang Joo , Lee Seungho , Lee Jung Han , Roh Myong‐Hoon , Lim Kwang‐Young , Kim Young‐Wook
Published: February 2009

Silicon carbide (SiC) nanoparticles were successfully synthesized by using carbothermal reduction method. Nanoparticles with zincblende structure (3C–SiC) could be prepared using polysiloxane as silicon source and phenol resin (MH) or xylene resin (YN) as carbon source. The sample YN has an average grain size of 22 nm, larger than that of the sample MH (8 nm). Raman spectroscopy revealed that all nanoparticle samples contain graphitic surface carbon layers. Oxygen contamination on the nanoparticle surface could be reduced by postfluorine treatment (MH‐F). But the sample MH‐F showed reduced SiC crystallinity compared with the sample MH. The nanoparticle samples exhibited an intensive emission band in the blue region observed by photoluminescence (PL) spectroscopy. The band‐gap energy of the nanoparticle samples is estimated to be ∼3 eV from the PL spectra, blueshifted by ∼0.6 eV from that of bulk 3C–SiC due to the quantum confinement effect.
In situ Spinel Expansion Design by Colloidal Alumina Suspension Addition
Authors: Braulio Mariana A. L. , Piva Matheus F. L. , E Silva Guilherme F. L. , Pandolfelli Victor C.
Published: February 2009

The incorporation of nano powders into refractory castables it is not a straightforward procedure, due to their agglomeration and sintering drawbacks. Considering the alumina grain size effect on the in situ spinel formation and the associated overall volumetric expansion, alumina–magnesia refractory castables containing different alumina sources were evaluated by the assisted sintering technique. Reducing the size of fine tabular alumina (<200 μm) led to lower expansion levels, indicating the main role of alumina grain size in this property. Regarding the reactive aluminas (nano alumina powder, hydratable alumina, and colloidal alumina), the composition containing colloidal alumina performed remarkably better, leading to the lowest in situ spinel expansion level as a consequence of its high sinterability. The use of nano scaled alumina suspensions was the most suitable alternative to inhibit the shortcoming of nano powder agglomeration. Conversely, the castable containing the nano alumina powder did not behave as expected. The present work pointed out that the use of nano powders in refractory castables is only feasible if the compound is fully dispersed. Otherwise, cheaper raw materials could provide even better results than those of nano agglomerated powders.
The effect of UVB irradiation on antibody responses during herpes simplex virus type 1 (HSV‐1) infections of mice
Authors: El‐Ghorr A. A. , Horsburgh G. , Norval M.
Published: February 2009

Ultraviolet B (UVB) exposure suppresses cell‐mediated immunity and may alter the cytokine profile, reducing T helper 1 (Th1) cytokines and promoting Th2 cytokines. Th1 cytokines enhance the production of immunoglobulin (Ig) G2a, IgG2b and IgG3 antibodies, while Th2 cytokines enhance the production of IgG1 and IgE antibodies. The effect of suberythemal UVB irradiation on antibody isotypes following infection of C3H/HeN mice with herpes simplex virus (HSV) was investigated using two protocols. First, mice were irradiated prior to two subcutaneous infections with HSV. Second, mice were immunised with inactivated HSV before being irradiated and challenged epidermally with HSV, which led to an increase in the size of the clinical lesions compared with unirradiated animals. In both models, the HSV‐specific IgG titre was not affected by the UVB exposure but, generally, the irradiated animals showed a small reduction in both Th1‐ and Th2‐associated HSV antibody isotypes. IL‐4 knockout (IL‐4‐/‐) mice were used to investigate the role of IL‐4 in UVB‐induced isotype switching. Here IL‐4‐/‐ and IL‐4+/+ strains were irradiated prior to primary and secondary epidermal infections with HSV, followed by measurement of antibody titres and lesion size. In both the mutant and parent mice, UV irradiation led to an increase in lesion severity. In IL‐4+/+ mice, UV exposure did not affect the HSV titre of any of the individual isotypes tested but did suppress the total IgG to HSV. This suppression may be due to UV‐induced IL‐4 release because, in the IL‐4‐/‐ mice, HSV IgG was elevated by the UVB irradiation. If UV modulates the immune response solely via the action of cytokines, then the down‐regulation of Th1 cytokines and upregulation of Th2 cytokines should be accompanied by antibody isotype switching from IgG2a and IgG3 towards IgG1 and IgE. This result was not obtained in the models tested, perhaps because HSV infection promotes such a complex array of innate and acquired immune responses that a clear effect on virus‐specific isotype production may not be apparent.
Relationship between minimal phototoxic dose and skin colour plus sun exposure history: a neural network approach
Authors: Rubegni P. , Cevenini G. , Flori M. L. , Barbini P. , Andreassi L.
Published: February 2009

Before beginning PUVA‐therapy it is important to accurately gauge an individual's degree of psoralen photosensitivity. This determination is usually based on an individual's skin phototype or minimal phototoxic dose. Since minimal phototoxic dose is technically complex and time consuming to measure, sun reactivity skin phototype is often used instead; however, it has recently been shown that skin phototype lacks specificity as a predictor of an individual's minimal phototoxic dose. In this study, an artificial neural network was developed to attempt to predict the minimal phototoxic dose from skin colour measurements combined with skin phototype. Our results showed that minimal phototoxic dose was predicted with an error less than 1 J/cm2in only about half the subjects. In conclusion, minimal phototoxic dose probably cannot be predicted with sufficient accuracy on the basis of skin colour and skin phototype alone.
Hepatic complications of erythropoietic protoporphyria*
Authors: Groß U. , Frank M. , Doss M. O.
Published: February 2009

A quarter of patients with erythropoietic protoporphyria develop mild to severe cholestatic liver disease. The determination of early indicators of hepatobiliary involvement are of pivotal importance to select patients for choleretic therapy. Porphyrin parameters were studied during ursodeoxycholic acid treatment in eight patients with protoporphyrin‐associated liver disease and eight patients with liver failure before and after liver transplantation. The patients with intrahepatic cholestasis exhibited excessive protoporphyrinemia (27 μmol/l) compared with controls (normal<0.64 μmol/l). Fecal protoporphyrin excretion decreased in patients with deterioration of liver function, whereas urinary coproporphyrin increased up to 2290 nmol/24 h (normal <119 nmol/24 h). Coproporphyrin isomer I proportion increased to 71±10% (x̄±SD, n=8) in patients with terminal liver failure (normal <31%). During therapy with ursodeoxycholic acid biochemical improvement occurred but without clinical remission in most cases. Eight patients underwent liver transplantation between 1987 and 1997. One patient died of liver failure. Two transplant recipients are in a good condition since 8 and 9 years, respectively. All explanted livers revealed micronodular cirrhosis and high protoporphyrin levels of about 25,000‐fold (x̄, n=3). Immediately after liver transplantation protoporphyrin in erythrocytes decreased to 46–96% of pre‐operative values. Coproporphyrin remained moderately elevated due to postoperative cholestasis. A post‐operative rise in fecal protoporphyrin elimination reflected sufficient biliary clearence of protoporphyrin by the transplant. In conclusion, moderate coproporphyrinuria with isomer I is the earliest sign of liver complications in erythropoietic protoporphyria. Progression of protoporphyrin induced toxic liver injury is indicated by excessive protoporphyrinemia and coproporphyrinuria with an isomer I proportion >71±10%, and reduction of fecal protoporphyrin excretion. Results suggest that therapy of intrahepatic cholestasis with ursodeoxycholic acid is only effective in the initial stages of liver disease in erythropoietic protoporphyria. In patients with severe cholestatic hepatic failure, liver transplantation is the treatment of choice.
Two patients with isoniazid‐induced photosensitive lichenoid eruptions confirmed by photopatch test
Authors: Lee A.‐Y. , Jung S. Y.
Published: February 2009

Causative agents of drug eruptions are frequently unknown, and skin tests with candidate drugs would be useful before systemic challenge. It remains to be clarified how phostosentive lichenoid drug eruptions are induced, but allergy, including delayed type allergy, has been suggested. Two patients who had taken anti‐tuberculous drugs developed a lichenoid drug eruption, primarily on sun‐exposed skin. Patch and photopatch tests were performed with each of the ingested drugs (10% in petrolatum). Photopatch tests to isoniazid (INH) were positive. These were confirmed by oral challenge followed by irradiation with UVA. In conclusion, photopatch tests facilitated identification of the causative drug in two patients with photosensitive lichenoid eruptions to INH.
Photosensitization of skin‐derived cell lines by Dimegin [2,4‐di‐(α‐methoxyethyl)‐deuteroporphyrin IX] in vitro
Authors: Fickweiler S. , Szeimies R.‐M. , Abels C. , Ponomarev G. V. , Hofstädter F. , Wolfbeis O. S. , Landthaler M.
Published: February 2009

The deuteroporphyrin‐IX derivative Dimegin [2,4‐di‐(α‐methoxyethyl)‐deuteroporphyrin IX] was investigated with respect to cellular uptake, intracellular localization and cell survival following photodynamic treatment in human cell lines derived from the skin (SCL1 and SCL2, squamous cell carcinoma; HaCaT keratinocytes; N1 fibroblasts). Using flow cytometry, we determined the cellular fluorescence as a marker of the uptake of Dimegin after incubation for 24 h. The intracellular localization of Dimegin was analysed using fluorescence microscopy and co‐staining with fluorescent dyes specific for cell organelles. Following irradiation with an incoherent light source (580–740 nm) using a light dose of 24 J/cm2, phototoxicity was determined by means of trypan blue dye exclusion, MTT assays and growth curves. The relative Dimegin fluorescence of the different cell lines declined as follows: SCL1>HaCat>N1>SCL2. Intracellular localization of Dimegin was found in the mitochondria. For all cell lines Dimegin concentrations above 15 mM yielded a significant phototoxic effect. The EC50 for SCL1 cells was 8.9±2.0 μM Dimegin. The EC50 for the cell lines increased as follows: SCL1<HaCaT<N1<SCL2, thus correlating with the cellular fluorescence of Dimegin. The results of the MTT assay were confirmed by trypan blue dye exclusion assay and growth curves. In conclusion, the study shows that Dimegin is an effective photosensitizer with a rapid mechanism of action in vitro, resulting in an immediate loss of plasma membrane integrity following irradiation.
Decreased p53 expression in chronically sun‐exposed human skin after topical photoprotection
Authors: Berne B. , Pontén J. , Pontén F.
Published: February 2009

UV‐induced DNA damage appears to play an essential role in skin car‐cinogenesis. Following acute UV irradiation, there is an overexpression of normal p53 protein in epidermal keratinocytes, representing a physiological response to DNA damage. Sun protection through topical sunscreens or clothing is believed to reduce the hazardous effects of UV irradiation and subsequently the risk of skin cancer. We have examined the effect of an SPF 15 topical sunscreen and blue denim fabric (SPF 1700) in chronically sun‐exposed human skin after sun exposure during a normal summer. Skin biopsies from sun‐protected and sun‐exposed skin were compared with respect to immunohistochemically detectable p53. This method provides a model for assessing the significance of different degrees of UV protection under physiological conditions. Our results show a significant reduction of p53‐positive cells in sun‐protected skin as compared with sun‐exposed skin. The reduction of p53‐positive keratinocytes differed between topical sunscreen (33% reduction) and blue denim fabric (66% reduction). Interindividual variations were large, possibly because of variations in sun exposure. These variations also suggest that mechanisms determining UV damage at the cellular level are complex. The role of residual p53‐positive keratinocytes after 2 months of total sun‐protection (i.e., SPF 1700) is discussed.
Phototesting in Oriental patients with lupus erythematosus
Authors: Leenutaphong V. , Boonchai W.
Published: February 2009

Light sensitivity is an important clinical characteristic of several forms of lupus erythematosus (LE). Recently, investigations have been able to induce LE‐like lesions in LE patients with UVA as well as UVB, although most of these studies were conducted in Caucasians. Thus, there is insufficient data on phototesting in Oriental patients with LE. The aim of this study was to evaluate light sensitivity in Oriental patients with LE. Fifteen patients with various forms of LE were tested. Patients were evaluated by provocative phototesting, and threshold doses of UVA and UVB radiation that produced erythema and pigmentation were determined. The minimal erythema doses (MED) of UVB, immediate pigment darkening (IPD), and minimal tanning doses (MTD) were within the normal range in LE patients compared to a control group. Skin lesions clinically and histologically compatible with LE were induced in two of six patients with SLE, and four of nine patients with DLE. These lesions developed in about 2 weeks (range 5 to 23 days) after irradiation and lasted approximately 1 to 3 months (47±24 days). The action spectrum of the induced lesions was within the UVB range in four patients, in the UVA range in one patient, and in the UVB and UVA ranges in one patient. We found no correlation between a positive history for UV sensitivity and phototest reactions. In conclusion, the incidence of positive phototest reactions in Oriental patients with LE seems to be similar to or a little lower than in Caucasians. There was no correlation between a positive history for UV sensitivity and phototest reactions.
Induction of complete wound healing in recalcitrant ulcers by low‐intensity laser irradiation depends on ulcer cause and size
Authors: Schindl M. , Kerschan K. , Schindl A. , Schön H. , Heinzl H. , Schindl L.
Published: February 2009

Chronic skin ulcers still represent a therapeutic challenge in dermatology. Among the various non‐invasive treatment modalities used for the improvement of impaired wound healing, low‐intensity laser irradiations are gaining an increasing body of interest. We used low‐intensity laser irradiations delivered by a 30 mW helium‐neon laser at an energy density of 30 J/cm2 three times weekly for the induction of wound healing in ulcers of diverse causes. Twenty patients with the same number of ulcers, which had previously been treated by conventional wound care for a median period of 34 weeks (range: 3–120 weeks) without any significant evidence of healing, were included in the study. Concerning the underlying disorders, patients were divided into four groups: diabetes, arterial insufficiency, radio damage and autoimmune vasculitis. In all ulcers, complete epithelization could be induced by laser therapy. No amputation or any other surgical intervention was necessary and no adverse effects of any kind were noted during low‐intensity laser treatment. Regarding the different diagnoses, a statistically significant difference was noted (P=0.008): ulcers due to radio damage healed significantly faster than those caused by diabetes (6 weeks [range: 3–10 weeks] vs. 16 weeks [range: 9–45 weeks], P=0.005). Wound healing in autoimmune vasculitis (24 weeks [range: 20–35 weeks]) required longer than in radiodermitis, although the difference was not significant.

In addition to the diagnosis, wound size was found to be an important factor influencing the duration of wound closure (P=0.028), whereas duration of previous conventional treatment (P=0.24) and depth (P=0.14) showed no effect. Our results indicate that low‐intensity laser irradiation could be a valuable non‐invasive tool for the induction of wound healing in recalcitrant ulcers, and that healing time is correlated with the ulcer cause and size.
PUVA‐induced lymphocyte apoptosis: Mechanism of action in psoriasis
Authors: Coven T. R. , Walters I. B. , Cardinale I. , Krueger J. G.
Published: February 2009

Psoralen plus ultraviolet A (PUVA), utilizing oral 8‐methoxypsoralen (8‐MOP), is a widely utilized and effective treatment for psoriasis vulgaris. Previous studies have suggested that PUVA's mechanism of action in psoriasis is a result of its direct lymphotoxic effects. Trimethylpsoralen (TMP), a potentially safer compound, has been found to be effective in psoriasis during bath water delivery. In this study we examined the relative anti‐lymphocytic effects of TMP and 8‐MOP through both flow cytometry and tissue analysis on lesional skin during clinical treatment. Based on FACS analysis on phytohemagglutinin‐activated lymphocytes, we found TMP to be nearly 10,000 fold more lymphotoxic compared to 8‐MOP. In addition, lymphocytes treated with 8‐MOP or TMP with UVA displayed DNA degradation patterns typical of apoptotic cell death. These findings were consistent with our investigation of treated psoriatic skin, with virtual elimination of epidermal CD3+ T‐cells following bath water treatment with TMP or 8‐MOP. These results support the theory that the therapeutic effects of PUVA stem from its toxic effects on activated lymphocytes. If further investigation supports TMP's lack of carcinogenicity, this potent lymphotoxic treatment may prove to be one of the safest and most effective treatments for psoriasis.
HIV, UV and immunosuppression
Authors: Akaraphanth R. , Lim H. W.
Published: February 2009

Cutaneous diseases are common manifestations of infection with human immunodeficiency virus (HIV). Phototherapy with ultraviolet B (UVB) and photochemotherapy with 8‐methoxypsoralen plus UVA (PUVA) have been used successfully to treat several of these skin conditions, including psoriasis, folliculitis, pruritus, and eczema. However, in view of the known immunosuppressive effects of UV radiation, concerns have been raised about potential adverse effects of UV on persons infected with HIV. In the following report, we review the effects of UV in HIV‐infected cell lines in vitro, in animal models, as well as in human studies. Based on currently available data, UV radiation, as used in phototherapy and photochemotherapy, appears to have no adverse effects in HIV‐infected individuals.
Pharmacokinetics of 8‐methoxypsoralen during extracorporeal photopheresis
Authors: Shephard S. E. , Nestle F. O. , Panizzon R.
Published: February 2009

Background/purpose: Extracorporeal photopheresis (ECP) is a widely used therapy for the treatment of diverse diseases such as cutaneous lymphomas and graft‐vs‐host disease. Knowledge of the effective concentration of 8‐methoxypsoralen (8‐MOP) in the photopheresis apparatus and the photodegradation time‐course of 8‐MOP during ECP is a prerequisite for a successful therapy. Methods: The time course of 8‐MOP concentration was measured in patients' serum and in the photoactivation chamber (so‐called buffy coat fraction) during ECP Samples were analyzed by high‐performance liquid chromatography. Half‐lives of 8‐MOP in both fractions were calculated assuming first‐order kinetics (exponential decay). Losses due to adsorption and photodegradation were investigated and the recovery of bioavailable 8‐MOP calculated. Results: In female patients (average age 61 ± 9 years) given 0.4–0.6 mg 8‐MOP/kg body weight in the form of Oxsoralen® capsules, peak serum concentrations averaged 420±80 ng/ml (n=8). In contrast, peak concentrations in the photoactivation chamber averaged only 134 ng/ml, or 32% of serum values. In serum, peak 8‐MOP concentrations were reached ≤40 min following ingestion; the half‐life of 8‐MOP in the serum was 50±14 min (n=7). The effective half‐life of 8‐MOP in the photoactivation chamber was considerably longer (about 4 h). The recovery of free, bioavailable 8‐MOP in the photoactivation chamber at the end of ECP averaged 42% of the applied dose; losses stemmed mainly from photodegradation of 8‐MOP and from adsorption of 8‐MOP to the surfaces of the apparatus. Conclusion: We conclude that interpretation of investigations on clinical success and dose‐response aspects of ECP must take into account the complex pharmacokinetic behaviour of 8‐MOP during the ECP procedure.
Narrowband UVB phototherapy for psoriasis: Results with fixed increments by skin type (as opposed to percentage increments)
Authors: Halasz C. L. G.
Published: February 2009

Many authors currently advocate 10–20% dosage increments between phototherapy sessions when treating psoriasis with narrowband ultraviolet B (UVB). However, such regimens are associated with a risk of significant erythema. In order to reduce this risk, a fixed increment regimen was developed using increments ranging from 30 mJ/cm2 for skin type II to 150 mJ/cm2 for type VI. Starting doses, also based on skin type, range from 180 to 400 mJ/cm2. Data from 20 patients with moderate to severe plaque psoriasis [13 male, 7 female, age range 17–74, skin types II (3), III (10), IV (3), V (1), VI (3)] completing 27 courses of phototherapy of more than 3 weeks' duration between 8/96 and 12/97 were compared. Complete, or near‐complete clearing occurred in 8/13 courses (62%) with a frequency of attendance (during the initial 24 sessions) of >2.5 sessions per week, 4/8 (50%) with a frequency of 2.0–2.5, and 1/6 (17%) with a frequency of <2.0. In the subset of patients taking low‐dose oral retinoids, rates of clearing were higher. Overall, 10 of 20 patients (50%) cleared, usually within 24–30 sessions. The average maximum dosage in such cases was 1400 mJ/cm2. There were only 13 instances of minor erythema, and 1 instance of severe erythema resulting in desquamation and requiring interruption of treatment. This was due to the inadvertent administration of an excessive 300 mJ/cm2 increment to a type VI patient. In summary, using a conservative fixed increment regimen, clearing of psoriasis is possible while minimizing the risk of serious erythema. Results are enhanced when patients attend 3 phototherapy sessions per week.
Treatment of severe recalcitrant dermatoses of the palms and soles with PUVA‐bath versus PUVA‐cream therapy
Authors: Grundmann‐Kollmann M. , Behrens S. , Peter R. U. , Kerscher M.
Published: February 2009

PUVA‐bath therapy developed into a first line topical PUVA therapy, and gel and cream preparations have been described as alternative modes of topical 8‐MOP application. Because bath‐PUVA can be difficult to manage, topical PUVA therapy using 8‐MOP gel or cream preparations may become an important alternative when treating localised skin diseases. However, controlled comparisons of efficacy with this alternative topical PUVA therapy are lacking. We therefore compared the efficacy of PUVA‐cream therapy with PUVA‐bath therapy in 12 patients with recalcitrant dermatoses of the palms and soles using a left/right trial design. These patients responded well to both treatment modalities, meaning that both could be used successfully to treat recalcitrant dermatoses of the palms and soles.
Artificial hardening for polymorphic light eruption: Practical points from ten years' experience
Authors: Man I. , Dawe R. S. , Ferguson J.
Published: February 2009

The conservative approach of sunlight avoidance and broad‐spectrum sunscreen is often disappointing in patients with moderate to severe polymorphic light eruption. A springtime course of prophylactic artificial hardening with ultraviolet B (UVB) phototherapy or psoralen plus ultraviolet A (PUVA) photochemotherapy will often allow patients to tolerate more sunlight and give them greater freedom during the summer. In this retrospective study we describe ten years' experience of such “desensitization” treatment. Individualized therapy with attention to detail will maximize the effectiveness of this treatment.
Calculation of erythema dose‐response curves using a spreadsheet
Authors: Davidson A. W.
Published: February 2009

A method of using an Excel spreadsheet is described which allows dose and erythema index values to be entered, a sigmoid curve fitted to the data, and a report generated. Summary statistics may be derived from the fitted curve. Data and statistics may be saved in a simple database. It is suitable for implementation by people who have no previous programming experience, although basic familiarity with spreadsheets is assumed.
Solar ultraviolet radiation exposure of infants and small children
Authors: Moise A. F. , Harrison S. L. , Gies H. P.
Published: February 2009

Townsville, in Queensland, Australia, experiences very high levels of ambient solar ultraviolet radiation (UVR) throughout the year and has a predominantly white population which is prone to developing skin cancer. The UVR exposure of 1‐year‐old and 2 1/2‐year‐old children raised in Townsville was measured using UVR‐sensitive polysulphone film badges. In two separate exposure studies undertaken for 7 days in October 1995 and 5 days in April 1997, exposure at the chest and shoulder for each subject was determined. The chest exposures for the 1‐year‐olds were significantly higher at weekends than on weekdays, whereas for the 2 1/2‐year‐old children the shoulder exposures were significantly higher at weekends than on weekdays. The median daily total exposure for 1‐year‐old infants was 0.4 SED (standard erythemal dose) for the chest and 0.4 SED for the shoulder. The median daily total exposure for 2 1/2‐year‐olds was 0.6 SED for the chest and 0.9 SED for the shoulder. Although the median daily total exposures were comparatively low, the maximum values for the chest and shoulder were 6.5 SED and 2.4 SED, respectively, for the 1‐year‐old infants, and 20.6 SED and 8.4 SED, respectively, for the 2 1/2‐year‐olds. While the 2 1/2‐year‐old children spent most of their time outside between 9 am and 4 pm, the 1‐year‐old infants spent more time outside before 9 am and after 4 pm. Exposure increases with age in early childhood. Increased mobility and a greater tendency to play outdoors is likely to account for the higher exposure levels in 2 1/2‐year‐old children, compared to 1‐year‐old infants.
An extract of Polypodium leucotomos appears to minimize certain photoaging changes in a hairless albino mouse animal model: A pilot study
Authors: Alcaraz M. V. , Pathak M. A. , Rius F. , Kollias N. , González S.
Published: February 2009

Chronic ultraviolet B (UVB) exposure of human or murine skin is known to induce cutaneous photoaging and enhanced carcinogenic risk. An extract of Polypodium leucotomos (PL), a tropical fern plant, has been known to exhibit interesting antioxidant and photoprotective properties against acute exposure to ultraviolet radiation. The objective of this preliminary (or pilot) study was to determine the photoprotective role of topically applied Polypodium leucotomos extract in the prevention or amelioration of cutaneous changes of photoaging in hairless mice. PL‐treated mice showed significant reduction of skinfold thickness than those observed in PL‐untreated controls. Additionally, PL‐treated mice showed a significantly lower degree of histologic parameters of photoaging damage, including dermal elastosis, compared with positive control mice. Interestingly, PL treatment also showed reduction in the number of mice showing skin tumors at 8 weeks after the cessation of the UVB exposure protocol. The results of this preliminary study illustrate that PL treatment helped to ameliorate and to partially inhibit some of the histologic damage associated with photoaging of skin and appeared to contribute to a decrease in the prevalence of UVB‐induced skin tumors in mice.
The photoprotective effect of ascorbic acid, acetylsalicylic acid, and indomethacin evaluated by the photo hen's egg test*
Authors: Neumann N. J. , Hölzle E. , Wallerand M. , Vierbaum S. , Ruzicka T. , Lehmann P.
Published: February 2009

The aim of the present study was to evaluate the supposed photoprotective effects of ascorbic acid, acetylsalicylic acid, and indomethacin by the photo hen's egg test, a recently developed new model for phototoxicity Therefore, in three independent experimental settings the blood vessel system of the embryo's yolk sac of 24 incubated hens' eggs (2 test groups) were exposed to 60 mJ/cm2 ultraviolet B (UVB) to induce severe phototoxic damage. Before UVB irradiation, one of these test groups was exposed additionally to one of the test substances and the other one to 0.9% sodium solution alone. To exclude plain toxic reactions, two additional test groups were exposed only to 0.9% sodium chloride solution or to one of the test substances alone. Over a test observation period of 24 h, the embryo lethality as well as the morphological changes of the yolk sac blood vessel system were observed. Ascorbic acid led to a significant and remarkable reduction of the UVB‐induced damage. Acetylsalicylic acid also showed a significant but lower photoprotective capacity. In contrast, indomethacin showed no photoprotective effects in the photo hen's egg test.
Temperatures reached inside stand‐up ultraviolet treatment boxes
Authors: Asawanonda P. , Ortel B. , Taylor C. R.
Published: February 2009

Heat generated within ultraviolet treatment units can exacerbate eczema. To document the actual temperature changes within the treatment units, we measured the air temperatures in standard stand‐up psoralen plus ultraviolet A (PUVA), narrowband ultraviolet B (UVB), broadband UVB, and combination UVA/UVB cabinets using a thermocouple thermometer. For the latter unit, we also measured the air temperatures with and without ventilation systems, and actual skin temperatures on individuals undergoing light treatment. The air temperatures rose significantly in all the treatment units, more so with PUVA and narrowband UVB boxes, and were highest with the ventilation systems shut off. Skin temperatures also rose significantly, but less dramatically. Ventilation is essential in maintaining comfortable temperatures within ultraviolet treatment units.
The clinical features and management of actinic prurigo: a retrospective study
Authors: Lestarini D. , Khoo L. S. W. , Goh C. L.
Published: February 2009

Actinic prurigo (AP) is a rare photodermatosis, mostly affecting young American Indian girls. A retrospective descriptive study was done in the National Skin Centre, Singapore. Our patients have different characteristics compared to the previous reports. Of the 11 cases found between 1990 and 1998, 10 were male. All of the patients had the onset in adulthood. The condition was recognised by the presence of papules and nodules on the sun‐exposed areas, predominantly on forearms and back of hands. Phototests revealed lowered minimal erythemal dose (MED) to ultraviolet A (UVA) alone in 2 patients and lowered MED to both UVA and UVB in another 4 patients. Patch, photopatch and histological examination did not show any significant finding. Sun protection, emollients and topical steroid were the baseline treatment for all patients. Intralesional steroid, systemic steroid, psoralen plus ultraviolet A (PUVA), azathioprine and thalidomide were used in some patients, with variable results.
Long‐term extracellular signal‐related kinase activation following cadmium intoxication is negatively regulated by a protein kinase C‐dependent pathway affecting cadmium transport
Authors: Martin Patrick , Boulukos Kim E. , Poggi Marie C. , Pognonec Philippe
Published: February 2009

Extracellular signal‐related kinase (ERK) is a well‐known kinase taking part in a signal transduction cascade in response to extracellular stimuli. ERK is generally viewed as a kinase that is rapidly and transiently phosphorylated following mitogenic stimulation. This activation results in ERK phosphorylating further downstream targets, thus transmitting and amplifying the original stimulus, and ultimately resulting in the onset of cellular proliferation and/or protection against apoptosis. More recently, several groups have identified a strikingly new type of ERK activation that results in cell death. This activation is very different from conventional ERK activation, as it occurs several hours after the original stimulation, and results in the sustained phosphorylation of ERK, which can be observed for up to several days. One way of inducing this delayed ERK activation is by low‐dose cadmium treatment. We show here that sustained ERK activation induced by cadmium in human kidney‐derived cells is inhibited following protein kinase C (PKC) activation, even when this activation occurs hours before intoxication. Furthermore, PKC inhibition results in an enhanced ERK activation in response to cadmium, even when inhibition is induced hours before intoxication. PKCε appears to be the most implicated isotype in this phenomenon. Finally, we present evidence suggesting that the ZIP8 transporter is involved in this process, as multiple small interfering RNAs against ZIP8 have a protective effect against cadmium treatment. Our results indicate that PKC activation negatively affects ZIP8 transporter activity, thus protecting cells against cadmium poisoning.