Miracle-dz/UniFAR-FTUs huggingface dataset:
Strategies to Overcome pH-Dependent Solubility of Weakly Basic Drugs by Using Different Types of Alginates

Weakly basic drugs demonstrate higher solubility at lower pH, thus often leading to faster drug release at lower pH. The objective of this study was to achieve pH-independent release of weakly basic drugs from extended release formulations based on the naturally occurring polymer sodium alginate. Three approaches to overcome the pH-dependent solubility of the weakly basic model drug verapamil hydrochloride were investigated. First, matrix tablets were prepared by direct compression of drug substance with different types of sodium alginate only. Second, pH-modifiers were added to the drug/alginate matrix systems. Third, press-coated tablets consisting of an inner pH-modifier tablet core and an outer drug/sodium alginate coat were prepared. pH-Independent drug release was achieved from matrix tablets consisting of selected alginates and drug substance only. Alginates are better soluble at higher pH. Therefore, they are able to compensate the poor solubility of weakly basic drugs at higher pH as the matrix of the tablets dissolves faster. This approach was successful when using alginates that demonstrated fast hydration and erosion at higher pH. The approach failed for alginates with less-pronounced erosion at higher pH. The addition of fumaric acid to drug/alginate-based matrix systems decreased the microenvironmental pH within the tablets thus increasing the solubility of the weakly basic drug at higher pH. Therefore, pH-independent drug release was achieved irrespective of the type of alginate used. Drug release from press-coated tablets did not provide any further advantages as compound release remained pH-dependent.
The impact of accessible surface on hydrogen bond formation

“All good proton donors and acceptors are used in hydrogen bonding” (M. C. Etter, Acc. Chem. Res., 1990, 23, 120–126). This is Margaret Etter's first rule, part of pioneering work which has proven both insightful and accurate over the intervening 20 years since its publication. In this work we question whether a good donor or acceptor can be identified solely from a chemical perspective, e.g. given only a chemical diagram. Results indicate that 2.5% of the organic structures in the Cambridge Structural Database which contain what would be considered a strong donor and an acceptor do not hydrogen bond. We have revealed in 2/3 of the cases, donors or acceptors with reduced accessible surface are responsible i.e. due to steric crowding by neighbouring atoms. We have further identified significant contrasts in the extent to which the degree of inaccessibility affects different donor and acceptor groups. This function-specific behaviour has been characterised in a predictive fashion. In the remaining structures we have also identified a number of other, more specific prohibitive factors. The results of this study will significantly enhance our ability to predict hydrogen-bonds in the future.
Low temperature low frequency noise in oxide and reoxidized-nitrided oxide films

The reliability of oxide and reoxidized-nitrided oxide (RNO) gate dielectrics was examined by comparing the low frequency noise characteristics at low temperature of p-channel devices before and after positive F-N stress. The RNO devices were found to have a better noise performance after F-N stress and were also found to have less interface state generation due to the warm-up process. However, the creation of negative fixed charge in RNO devices has a severe effect on the threshold voltage
Stochastic modelling of migration from polyolefins

A method is presented to predict diffusion coefficients in polyolefins using stochastic modelling. A large number of experimental diffusion coefficients, published in the literature as one dataset, was used to derive probability distributions of diffusion coefficients in the polymers low-density polyethylene and linear low-density polyethylene, medium- and high-density polyethylene, and polypropylene. An equation is proposed to describe the diffusion coefficient as a function of the molar mass of the migrant. Model parameters and standard deviations are predicted by minimizing the sum of squared errors and the residuals are used to check the assumed types of probability distribution. The experimental data can be described by a log-normal distribution. It is shown how the derived probability distributions can be used as input for migration predictions. The method presented provides information about the most likely migration results for a given packaging-food simulant combination. This is important for prediction of the probability that a given migration limit may be exceeded. © 2005 Society of Chemical Industry.
Evaluation of Integrated Fixed Film Activated Sludge Wastewater Treatment Processes at High Mean Cells Residence Time and Low Temperatures

Suspended solids mean cells residence time (MCRT) and temperature are two key parameters for designing Integrated Fixed Film Activated Sludge (IFAS) wastewater treatment processes, as an alternative for achieving year-round nitrification. It has been demonstrated from both full-scale and bench-scale studies that IFAS can accomplish year-round nitrogen removal and denitrification in aerobic zones in winter when operated with suspended growth MCRTs less than the critical MCRT for nitrifiers, thus avoiding increasing reactor or clarifier volumes. The objective of this study was to investigate the performances of IFAS systems that were operated at relative high MCRT compared to nitrifier washout MCRT and low temperature for biological nutrient removal. The comparison between two IFAS systems with Accuweb media in both the anoxic and aerobic zones, and a conventional three zone biological nutrient nemoval (BNR) system was conducted at 10°C with a 10 day MCRT using the UCT/VIP configuration for both systems and feeding with Blacksburg domestic wastewater. Influent flow was split 50% to the first anaerobic reactor and 50% to the first anoxic reactor to enhance denitrification in one of IFAS systems and the conventional BNR control system whereas 100% of the influent flow was fed to the first anaerobic reactor in the other IFAS system. The data from this investigation indicated that the performances of the control and IFAS systems were insignificantly different under the experimental operating conditions for both biological nitrogen and biological phosphorus removal except for IFAS with integrated fixed film media in the anoxic zone and when 50% of the influent was added directly to the first anoxic reactor.
Zintl Phases as Thermoelectric Materials: Tuned Transport Properties of the Compounds CaxYb1–xZn2Sb2

Zintl phases are ideal candidates for efficient thermoelectric materials, because they are typically small‐bandgap semiconductors with complex structures. Furthermore, such phases allow fine adjustment of dopant concentration without disrupting electronic mobility, which is essential for optimizing thermoelectric material efficiency. The tunability of Zintl phases is demonstrated with the series CaxYb1–xZn2Sb2 (0 ≤ x ≤ 1). Measurements of the electrical conductivity, Hall mobility, Seebeck coefficient, and thermal conductivity (in the 300–800 K temperature range) show the compounds to behave as heavily doped semiconductors, with transport properties that can be systematically regulated by varying x. Within this series, x = 0 is the most metallic (lowest electrical resistivity, lowest Seebeck coefficient, and highest carrier concentration), and x = 1 is the most semiconducting (highest electrical resistivity, highest Seebeck coefficient, and lowest carrier concentration), while the mobility is largely independent of x. In addition, the structural disorder generated by the incorporation of multiple cations lowers the overall thermal conductivity significantly at intermediate compositions, increasing the thermoelectric figure of merit, zT. Thus, both zT and the thermoelectric compatibility factor (like zT, a composite function of the transport properties) can be finely tuned to allow optimization of efficiency in a thermoelectric device.
Chemical composition of essential oils of Algerian Myrtus communis and chiral analysis of their leave volatiles

The essential oils of leaves and twigs of Myrtus communis with black and white fruits were analyzed by GC and GC/MS. The leaves were rich in essential oil (0.77–0.94%) than the twigs (0.05%). More than forty compounds were identified in each leaf essential oils, the major compounds were α-pinene/1,8-cineol with different percent compositions (33.4/42.4%) and (39.3/33.3%) in M. communis with white and black fruits, respectively. Thirty-eight compounds were identified in the essential oils of the twigs among which the main compounds were p-cymene (17.7%), α-pinene (10.8%), 1,8-cineol (13.5%), and limonene (10.7%). While the volatile fraction of M. communis leaves having white fruits extracted by HS-SPME was characterized by high content of limonene (almost 29%), those with black fruits were dominated by cis-β-terpineol (ca. 29%). The enantiomeric ratio of monoterpenes present in the headspace of all M. communis samples determined using enantioselective gas chromatography/mass spectrometry showed (+)/(−)-α-pinene ratio close to 95/5% and exclusive presence of (+)-antipode for limonene.
Surface Plasmons on Metal Nanoparticles: The Influence of Shape and Physical Environment

The surface plasmon response of metal nanoparticles is studied for different shapes and physical environments. For polyhedral nanoparticles, the surface plasmon resonances are studied as a function of the number of faces and vertices. The modification of these surface plasmons by different surrounding media and the presence of a substrate or other nanoparticles is also discussed. We found that polyhedral nanoparticles composed with less faces show more surface plasmon resonances, and as the nanoparticle becomes more symmetric, the main surface plasmon resonance is blue-shifted. It is also found that the corners induce more surface plasmons in a wider energy range. In the presence of a substrate, multipolar plasmon resonances are induced, and as the nanoparticle approaches the substrate, such resonances are red-shifted. The interaction among nanoparticles also induces multipolar resonances, but they can be red or blue-shifted depending on the polarization of the external field.
Nutritional Aspects of Street Foods in Botswana

Street foods provide a source of affordable nutrients to the majority of the people especially the low- income group in the developing countries. Street foods are ready-to-eat food items retailed by vendors and can be snacks, main meals, or beverages. They are usually sold from pushcarts or baskets, or stalls or shops. Urban Street food vending provides employment and income for many people, and can provide economic support to small farmers as an outlet for rural produce. In Botswana the majority of street food vendors are women, while in Bangladesh the opposite occurs with women-primarily the vendors' wives and female children-are involved in food preparation. Examples of street foods in Botswana are Fat cakes (magwinya) doughnuts; corn-on-the-cob (mmidi) crisp (madubula) extruded products, roasted beef and chicken, apples, bananas, pears, oranges, grapes and mangoes. Dried mophane worms-a high protein larvae of the emperor moth, imbrasis belina (Westwood), soft drinks, juices, and ice pop, Rice served with chicken or beef with gravy and salads, Maize meal with meat served with beef or chicken with gravy, "Samp" (broken maize corns) served with beef or chicken with gravy, "Dikgobe" "Samp" cooked with beans, "Bogobe" sorghum meal served with meat. Street foods are also prepared in a variety of ways including frying, roasting, boiling, baking and steaming, as well as served raw. Some populations, such as students and the homeless, are almost totally reliant on street foods, whereas other population groups buy them occasionally. Further an EU study in Botswana showed that the consumers of street foods in Gaborone and Francistown included both the working class and professionals. The number of customers served per day varied form 20 to 40 people. The vendors reported that the most food sold was maize-meal porridge, followed by rice, "Samp" and sorghum porridge in that order. Also dumplings, plain "Samp", "Samp" and beans were sold in smaller quantities. Due to lack of transportation, the street food vendors in this study reported that the frequency of buying raw materials was high. Finally the paper reviews the importance of the nutritional issues of street foods due to the fact that most villages in Botswana today are urbanizing and more street foods are likely to be consumed. Also the improvement of the health of the population must be of paramount concern to every one as it had been shown that HIV/AIDS has a relationship with nutrition.
HEAVY METAL ACCUMULATION AND CHEMICAL COMPOSITION OF ESSENTIAL OILS OF SALVIA OFFICINALIS CULTIVATED ON HEAVY METAL CONTAMINATED SOILS

Comparative research has been conducted to allow us to determine the content of heavy metals and chemical composition of Salvia officinalis L oils, as well as to identify the possibility of Salvia officinalis L. growth on soils contaminated by heavy metals. The experimental plots were situated at different distances of 0.5 km and 15 km, respectively, from the source of pollution the Non-Ferrous-Metal Works (MFMW) near Plovdiv, Bulgaria. On reaching flowering stage the Salvia officinalis L plants were gathered. The content of heavy metals in different parts of Salvia officinalis L. (roots, stems, leaves and inflorescences) was determined by ICP. The essential oil of the Salvia officinalis L. was obtained by steam distillation in laboratory conditions which was analyzed for heavy metals and its chemical composition was determined. Salvia officinalis L. is a plant which is tolerant to heavy metals and can be grown on contaminated soils. Favorable is also the fact that heavy metals do not influence the development of the Salvia officinalis L. as well as on the quality and quantity of the essential oil. Twenty-nine components were identified in the oil. The main compounds of essential oi were as follows: α-thujone (15.927-18.912), camphor (16.839-17.826), trans-thujone (5.379-11.575), 1,8-cineole (6.891-7.625), camphene (6.024-6.514), α-humulene (5.395-6.098), borneol (4.591-5.394), (e)-β-caryophyllene (3.868-4.576), limonene (3.458-4.612), bornyl acetate (1.621-3.194), viridiflorene (2.449-5.633), β-pinene (2.174-2.223), allo-aromadendrene (2.034-4.777). The compounds in the essential oil that decreased as a result of heavy metals pollution are limonene, bornyl acetate and allo-aromadendrene, while the α-thujone, trans-thujone, camphor and viridiflorene significantly increased. Observed increase of the levels of α-thujone, trans-thujone, and camphor level in the leaves of sage grown on heavy metals polluted soil indicated an improvement of the essential oil quality. The essential oil of Salvia officinalis L. can be a valuable product for the farmers from the polluted regions.
Enzyme‐caytalyzed oxidation of cholesterol in supercritical carbon dioxide

Supercritical carbon dioxide was studied as a solvent for the enzymatic oxidation of cholesterol with molecular oxygen. Enzymes isolated from Streptomyces sp. , Norcardia sp. , Pseudomonas sp. , and Gloeocysticum chrysocreas are active in supercritical carbon dioxide. For the oxidation of cholesterol to cholest-4-ene-3-one (via cholesterol oxidase) from Gloeocysticum chrysocreas, turnovers are almost two orders of magnitude higher than those found in aqueous solutions; initial rates of the reaction catalyzed by Streptomyces sp. in supercritical carbon dioxide are comparable to or greater than those found in aqueous solutions. Cholesterol oxidase from Gloeocysticum chrysocreas is stable in supercritical carbon dioxide at 100 bar and 35°C, while the enzyme from Streptomyces sp. is not. A trace amount of water is necessary for catalysis in carbon dioxide. The rate of oxidation is increased markedly by addition of small amounts of tert-butanol and iso-butanol, moderately by ethanol, slightly by acetone and n-butanol, and not at all by addition of methanol. Solubility data cannot explain these observations. EPR spectroscopy reveals no large conformational changes in the enzyme from Gloeocysticum chrysocreas as a function of carbon dioxide pressure or cosolvent addition. However, EPR spectroscopy indicates that aggregation of cholesterol molecules in supercritical carbon dioxide is strongly affected by changes in pressure or cosolvent content. The degree of cholesterol aggregation correlates well with observed rate enhancements.
Effect of electron beam irradiation and poly(vinyl pyrrolidone) addition on mechanical properties of polycaprolactone with empty fruit bunch fiber (OPEFB) composite

Biodegradable composites or green composites were prepared by melt blending technique using polycaprolac- tone and oil palm empty fruit bunch fibre (OPEFB). Since OPEFB is not compatible with PCL a binder, poly(vinyl pyrroli- done), (PVP) was used to improve the interaction between PCL and OPEFB. The composites produced were irradiated using electron beam to improve the mechanical properties. The tensile, flexural and impact strengths of PCL/OPEFB com- posites were improved by addition of 1% by weight of PVP and irradiated with 10 kGy of electron beam. The FTIR spec- tra indicate a slight increase of frequencies at C=O peaks from 1730 to 1732 cm-1 after irradiation indicates some interaction between C=O and O-H. The surface morphology of the facture surface obtained from tensile test shows no fibre pull out indicating good adhesion between the OPEFB and PCL after addition of PVP.
Hydrothermal fabrication of W18O49 nanowire networks with superior performance for water treatment

W18O49 nanowire networks with an excellent water treatment ability are obtained by a facile hydrothermal method. The products show superior adsorption for MB (201 mg g−1), RhB (120 mg g−1) and Pb(II) (192 mg g−1) due to their large special surface (223 m2 g−1) and special network nanostructures.
Radical Addition Reactions of Phosphorus Hydrides: Tuning the Reactivity of Phosphorus Hydrides, the Use of Microwaves and Horner–Wadsworth–Emmons‐Type Reactions

The reactivity of phosphorus hydrides in radical addition reactions are compared, and the substituents on phosphorus are shown to affect the efficiency of the reactions. The change in reactivity is attributed to the different bond dissociation energies of the P–H bonds, which have been calculated. Phosphorus hydrides with particularly weak P–H bonds are shown to undergo radical additions by microwave irradiation, in the absence of conventional initiators. These radical addition reactions produce phosphonothioates, phosphinothioates and phosphane sulfides, which react in HWE-type reactions, to afford substituted alkenes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Microloading effect in reactive ion etching

The etch rate of silicon, during reactive ion etching (RIE), depends on the total exposed area. This is called the loading effect. However, local variations in the pattern density will, in a similar way, cause local variations in the etch rate. This effect is caused by a local depletion of reactive species and is called the microloading effect. Silicon wafers patterned with silicon dioxide have been etched in order to study the microloading effect. The pattern consists of a large exposed area and narrow lines at different distances from the edge of the large area. This arrangement makes it possible to study how the distance from the large area, which depletes the etchants, influences the etch rate. The influence of different processing parameters like, e.g., pressure, gas flow rate, and flow direction on the microloading effect have been investigated. It has been found that the microloading effect is small (<10%) compared to other pattern dependent nonuniformities. It is also shown that the nonuniformitie.
Add‐on laser tailored selective emitter solar cells

An elegant laser tailoring add‐on process for silicon solar cells, leading to selectively doped emitters increases their efficiency η by Δη = 0.5% absolute. Our patented, scanned laser doping add‐on process locally increases the doping under the front side metallization, thus allowing for shallow doping and less Auger recombination between the contacts. The selective laser add‐on process modifies the emitter profile from a shallow error‐function type to Gaussian type and enables excellent contact formation by screen printing, normally difficult to achieve for shallow diffused emitters. The significantly deeper doping profile of the laser irradiated samples widens the process window for the firing of screen printed contacts and avoids metal spiking through the pn‐junction. Copyright © 2010 John Wiley & Sons, Ltd.
Geikielite–ecandrewsite solid solutions: synthesis and crystal structures of the Mg1−xZnxTiO3 (0 ≤x≤ 0.8) series

The crystal structures of members of the geikielite-ecandrewsite solid solution series, Mg(1 - x)Zn(x)TiO(3) (0 < or = x <or = 0.8 a.p.f.u. Zn; a.p.f.u. = atoms per formula unit), synthesized by ceramic methods in air at ambient pressure, have been characterized by Rietveld analysis of X-ray powder diffraction patterns. These synthetic titanates adopt an ordered R3; structure similar to that of ilmenite. The maximum solubility of Zn in MgTiO(3) is considered to be approximately 0.8 a.p.f.u. Zn, as compounds with greater Zn content could not be synthesized at ambient conditions. Data are given for the cell dimensions and atomic coordinates, together with bond lengths, volumes and distortion indices for all the coordination polyhedra. Within the solid-solution series unit-cell parameters and unit-cell volumes increase with Zn content. All compounds consist of distorted (Mg,Zn)O(6) and TiO(6) polyhedra and, in common with geikielite and ilmenite (sensu lato), TiO(6) polyhedra are distorted to a greater extent than (Mg,Zn)O(6). The displacements of (Mg,Zn) and Ti from the centers of their coordination polyhedra vary insignificantly with increasing Zn content. The interlayer distance across the vacant octahedral site in the TiO(6) layer decreases slightly with the entry of the larger Zn(2+) cation into the (vi)A site. The empirically obtained upper limit of the Goldschmidt tolerance factor (t) for A(2+)BO(3) compounds adopting an ordered R3; structure is 0.755. The absence of natural solid solutions between geikielite and ecandrewsite seems to be due to the contrasting geochemistry of Mg and Zn rather than for crystallochemical reasons.
Fe2+ and Fe3+ quantification by different approaches and fO₂ estimation for Albanian Cr-spinels

Abstract Fourteen Cr-spinels from Albanian ophiolites were examined. Fe2+/Fe3+ ratios were obtained by 57Fe Mössbauer spectroscopy (MS) and compared with ratios retrieved by electron microprobe analyses (EMPA). MS spectra were collected at both 298 K (RT) and 77 K (LT), and fitted using various interpretative models. Fe3+ contents by EMPA, calculated from spinel stoichiometry, are almost always underestimated with respect to those obtained by MS. Moreover, Fe3+ contents by MS-RT are shown to be somewhat overestimated with respect to those by MS-LT, which are proved to be the most reliable. On basis of MS results, Albanian Cr-spinels proved to be non-stoichiometric, with an oxidation degree, z, ranging from 4 to 49%. Our results indicate no dependence of z on sample provenance, but suggest a strong dependence on spinel composition. Chemical data of Albanian spinel and associated olivine were used to estimate fO₂ via oxygen geobarometry. Notably, fO₂ values calculated on basis of the EMPA data are always largely underestimated with respect to those obtained on basis of MS data. However, fO₂ values calculated on basis of MS-RT data are equal to or higher than (up to 0.2 log units) fO₂ values based on MS-LT data. The increase in fO₂ responsible for spinel oxidation was tentatively estimated to be less than one log unit for poorly oxidized samples, but up to 6 log units for the most oxidized samples.