Miracle-dz/UniFAR-FTUs huggingface dataset:
The biosynthesis of fungal metabolites. Part V. Structure of variecoxanthones A, B, and C, metabolites of Aspergillus variecolor; conversion of variecoxanthone A into (±)-de-C-prenylepishamixanthone

Variecoxanthones A, B, and C, metabolites of a variant strain of Aspergillus variecolor are shown to be 8-hydroxy-1-hydroxymethyl-3-methyl-2-(3-methylbut-2-enyloxy)-(IV), 8-hydroxy-1-hydroxymethyl-3-methyl-5-(3-methylbut-2-enyl)-2-(3-methylbut-2-enyloxy)-(V), and 5-(2,3-epoxy-3-methylbutyl)-8-hydroxy-1-hydroxy-methyl-2-(3-methylbut-2-enyloxy)-xanthone (VI), respectively. These structures were established by detailed spectroscopic comparisons with shamixanthone (I) and tajixanthone (II) and by hydrogenolysis of variecoxanthone A to 2,8-dihydroxy-1,3-dimethylxanthone (X). Acid-catalysed cyclisation of the variecoxanthone-A-derived compound, 1-formyl-8-hydroxy-3-methyl-2-(3-methylbut-2-enyloxy)xanthone (XI), gave 1,2-cis-2,3-dihydro-1,11-dihydroxy-2-isopropenyl-5-methylpyrano[3,2-a]xanthen-12(1H)-one (XIII). The cis-relationship of the 1- and 2-substituents in this compound and the corresponding trans-relationship in shamixanthone are confirmed by comparison of 1H couplings in the hydrogenated derivatives (XIV) and (III), respectively with those in the synthetic 1,2-cis- and 1,2-trans-2,3-dihydro-1-hydroxy-2-isopropyl-7-methyl-1H-benzopyrans (XVI) and (XVII), respectively, prepared by reduction of the corresponding chromone (XVIII) with sodium borohydride. The relative stereochemistry of compounds (XVI) and (XVII) was determined by lanthanide-induced shift studies on their respective 13C and 1H n.m. r. spectra. The mechanistic and biogenetic implications of the acid-catalysed cyclisation of compound (XI) are discussed.
ADSORÇÃO DE ÁCIDOS HÚMICOS EM LATOSSOLO ROXO NATURAL E TRATADO COM OXALATO DE AMÔNIO

The adsorption of two humic acids (HA) was carried out on a natural Oxisol (natural LR) and on an ammonium-oxalate treated sample (treated LR), in order to investigate the adsorption mechanisms and the main functional groups involved and relate the adsorptive capacity with the chemical and molecular characteristics of the adsorbates. The HA extracted with 0.5 N NaOH solution from a coal sample (HAc) and from a Mollisol sample (HAs) were characterized by elemental analysis and 13C-NMR spectroscopy. The experimental data were fitted according to the equation y = A tanh Bx and the model of Langmuir was also applied. The adsorbed samples were analyzed by Diffuse Reflectance Fourier Transformed Infrared Spectroscopy (DRIFT). The HA adsorption on the natural LR was of a chemical nature, with the ligand exchange reaction between the carboxyl groups and the mineral surfaces being an important mechanism, as shown by DRIFT. The AHc had a higher aromatic character and a higher carboxyl content in its molecule and was adsorbed in greater quantity than the AHs in both adsorbents. This result also suggests a possible participation of aromatic moieties in the organo-mineral interaction. The treated LR, which had a higher specific surface area (SSA = 140.9 m2 g-1), showed a greater adsorptive capacity than the natural LR (SSA = 66.1 m2 g-1). The higher SSA in the treated sample was related to the breakup of microaggregates by the oxalate treatment, caused by the extraction of the cementing portion of iron oxides that bonded the particles together. The interaction in this adsorbent, as estimated by the parametrization y = A tanh Bx, showed higher chemical affinity than in the natural sample. This can be related to the adsorbed oxalate that created hydrophobic adsorption sites, the exposure of more reactive sites after the treatment and the lower pH value. The Langmuir model was adequate to explain the adsorption in the natural sample, while in the treated sample, the results obtained were not satisfactory. Generally, the proposed parametrization y = A tanh Bx yielded the better fit (i.e. higher R2) in comparison to the Langmuir equation.
Capability of plasma‐enhanced chemical‐vapor‐deposited SiO2 films as diffusion barriers on InGaAs

Results on the diffusion behavior of InGaAs host atoms as well as Zn and Cd atoms in plasma‐enhanced chemical‐vapor‐deposited SiO2 layers are reported. The group‐III elements In and Ga diffuse very fast in SiO2 at annealing temperatures from 400 to 600 °C. A mobilization of these species by OH groups is proposed. An As diffusion can only be observed in the case of semiconductor samples etched in a H2SO4 solution before SiO2 deposition. An As‐rich interface layer produced by this etchant is assumed to act as exhausting source for mobile As‐O complexes. The InGaAs host atoms could be detected up to a concentration level of about 1018 cm−3 by secondary‐ion‐mass spectroscopy in the SiO2 films after annealing. Their effective diffusion coefficients were estimated to be in the order of 10−15–10−13 cm2/s in the investigated temperature range. Activation energies of about 0.6 eV (In), 0.3 eV (Ga), and 0.8 eV (As) could be determined. The In/Ga out‐diffusion was accompanied by the occurrence of two new peaks in th.
Heat of polymerization of phenyl glycidyl ether and of an epoxy resin

A differential thermal analysis apparatus was constructed for the measurement of heats of polymerization. It featured an active cell in which the reacting mixture was contained in expendable thin-walled, narrow, cylindrical brass, or aluminum cartridges. The cartridges were tightly pressed into holes drilled into the body of the active cell and they, along with the solid reaction product, could be ejected therefrom at the completion of the reaction. A calibration cell was provided with small electric heaters which allowed known amounts of heat to be supplied to the apparatus in calibration runs. With this apparatus the mean value for three determinations of the heat of polymerization of epoxy resins, ca. 22 to 26 kcal. /mole, could be measured to within a standard error of 0.37 kcal. /mole (i.e., confidence limits of ±0.75 kcal./mole at the 95% confidence level). The heats of polymerization of phenyl glycidyl ether and of an epoxy resin were measured with ten and nine different curing agents, respectively. Primary amine curing agents released about 26 kcal. /mole of epoxide reacted, tertiary amines, and boron trifluoride-ether complex each released about 22 kcal. /mole. Mixed-type curing agents, which could react in part as tertiary amines, or boron trifluoride, and in part as primary amines could liberate intermediate amounts of heat.
Chlorine Dioxide Effects on THMFP, TOXFP, and the Formation of Inorganic By-products

of chlorite formation, and (3) to investigate the stability of chlorite in treated water and its interaction with chlorine. Results of these experiments showed that chlorine dioxide can reduce THM and TOX precursor concentrations and that when added to raw water, chlorine dioxide will not persist long enough to maintain oxidizing conditions through flocculationsedimentation basins. Utilities should be able to meet the recommended limit of 1.0 mg/L for the sum of the residual chlorine dioxide species by not exceeding a chlorine dioxide dosage of 1.2-1.4 mg/L.
Urban Soil in Landscape Design

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Comparisons of Phosphorothioate and Phosphate Monoester Transfer Reactions: Activation Parameters, Solvent Effects, and the Effect of Metal Ions

The thermodynamics, pH dependency, solvent effects, and the effect of divalent metal ions have been examined for the hydrolysis reactions of the phosphorothioate monoester p-nitrophenyl phosphorothioate (pNPPT) and compared with those of the corresponding phosphate monoester, p-nitrophenyl phosphate (pNPP). The pH dependency for pNPPT hydrolysis mirrors that for typical phosphate monoesters, with the monoanion being the most reactive species. The ratio of the rate constants for pNPPT hydrolysis to that for pNPP is 1380 for the monoanion reactions and 12.6 for the dianion reactions at 39 °C. The free energy of activation for hydrolysis of the pNPPT dianion in water is 27.9 kcal/mol versus 29.5 kcal/mol for pNPP; for the monoanion reactions the values are 22.2 kcal/mol for pNPPT and 26.8 kcal/mol for pNPP. The free energies of solvation for pNPPT and pNPP are within 0.1 kcal/mol of each other despite the poorer hydrogen bonding ability of sulfur versus oxygen. This minimal difference in ground-state energie.
Understanding and Quantifying iDS-VDSOverlap Losses in Switched-Inductor Power Supplies

IV-overlap power losses play an important role in the overall conversion efficiency of a switched-inductor power supply, which is why a clear understanding of its mechanism is necessary. This paper proposes an insightful model with device-based expressions. The model accounts for the non-linear and dynamic behavior of gate capacitances in switching MOSFETs and reverse-recovery effects produced by interconnected diodes, which are largely absent in the state of the art. Calculated and simulated overlap losses with and without reverse recovery are within ±10%.
Aspects of plutonium solution chemistry

The effect of pH and complexation on the relative stabilities of the oxidation states of Pu is discussed. A set of ionic radii are presented for Pu in different oxidation states and different coordination numbers. A model for Pu hydration is presented and the relation between hydrolysis and oxidation state evaluated, including the problem of hydrous polymerization. Complexation of Pu is discussed in terms of the relative stabilities of different oxidation states and the effective ionic charge of PuO/sub 2//sup +/ and PuO/sub 2//sup +2/. An equation is proposed for calculating stability constants of Pu complexes and its correlation with experimental values demonstrated. The competition between inner vs outer sphere complexation as affected by the oxidation state of Pu and the pKa of the ligand is reviewed. Two examples of uses of specific complexing agents for Pu indicate a useful direction for future studies. 29 references, 8 figures, 3 tables.
BEST MIXING PRACTICES TO MINIMIZE THE PARTICLE SIZE IN RECONSTITUTED NONFAT DRY MILK

The objective was to determine processing parameters that would minimize the particle size of reconstituted nonfat dry milk (NDM). Four mixing parameters were evaluated: equipment (blender versus recirculation), shear rate (high versus low), mixing temperature (4 versus 22C) and holding temperatures (4 versus 22C). In a second experiment, lab-scale homogenization and pH adjustment were evaluated. NDM reconstituted in a blender at 22C had the smallest particle sizes (0.133 to 0.135 µm). Shear rate did not affect particle size. Homogenization induced multimodal particle size distributions within a single dispersion, and this effect was exacerbated if the reconstituted NDM was adjusted to pH 5, 6 or 7. Changes in casein micelle structure may explain the effect of homogenization on particle size. PRACTICAL APPLICATIONS Mixing practices vary in a manufacturing setting, and this work shows that the particle size in reconstituted nonfat dry milk (NDM) was minimized using blender-style equipment and ambient temperatures (22 versus 4C). Homogenization is a process step used to manufacture beverages as it aids ingredient mixing and component interactions, and potentially extends stability. But in this work, homogenization induced aggregate formation of smaller-sized particles in reconstituted NDM. At a beverage pH of 5, the aggregates destabilized the beverage, but this was not observed in beverages from pH 6 to 7. Thus, in the formulating and processing of dairy-based beverages, homogenization should be evaluated for impact on overall stability.
Efficient oxidation of phenyl groups to carboxylic acids with ruthenium tetraoxide. A simple synthesis of (R-γ-caprolactone, the pheromone of Trogoderma granarium).

The oxidation of aromatic rings to carboxylic acids with ruthenium tetraoxide is shown to be a very efficient and simple reaction using periodic acid as the stoichiometric oxidant in a biphasic solvent system (CCl 4 , CH 3 CN, H 2 O). The reaction can be very sensitive to the nature of the ring substituents when more than one aromatic ring is present. The procedure is compatible with other functional groups except for those that are quite acid sensitive. A simple synthesis of (R)-γ-caprolactone employs Sharpless asymmetric epoxidation and the presented oxidation procedure as key steps
Structure refinement of monoclinic 12‐layer TaNi3 with β‐NbPt3 type. New crystallographic descriptions of this type and of the Nb3Rh5 type based on smaller unit cells

Nouvelle description de l'arrangement atomique dans β-NbPt 3 et Nb 3 Rh 5 avec des mailles reduites au tiers du volume des mailles originales. β-NbPt 3 cristallise dans P2 1 /m avec a=4,870, b=5,537, c=9,268 A, β=100,62°, et Nb 3 Rh 5 cristallise dans P2/m avec a=4,772, b=2,806, c=6,949 A, β=103,76°. L'affinement de la structure a 12 couches de TaNi 3 avec le type β-NbPt 3 donne P2 1 /m a=4,5319, b=5,1253, c=8,632 A, β=100,79°, Z=4; affinement jusqu'a R=0,062
Supporting Information Gene flow at the leading range edge-the long-term consequences of isolation in European Beech ( Fagus sylvatica

Individual-based assignment methods were performed on the adult cohort using GENELAND 4.0. 4 (Guillot et al., 2005) a spatially explicit Bayesian clustering model. Seedlings were excluded from cluster analysis as significant deviations from Hardy-Weinberg equilibrium were found in six out of the 14 sites, as well as significant isolation-by-distance in seedlings (slope 0.026, p < 0.01) deviating from model assumptions for both clustering programs (STRUCTURE methods described below). Although isolation-by-distance was present, it was weaker in adults (slope 0.012, p < 0.05). Site GAR was removed from analysis as it was exclusively assigned to a cluster which displayed significant deviations from Hardy-Weinberg equilibrium and linkage disequilibrium.
Squeezing wastes in a wastewater treatment plant.

In this study, the performance of an anaerobic digester placed in a conventional wastewater treatment plant was evaluated. For that purpose, two different kinds of sludge were studied: a mixture of primary and secondary sludge, i.e. waste sludge, and the sludge after being anaerobically degraded, i.e., stabilized sludge. The practical biogas potential of the two wastes was studied in batch anaerobic reactors under mesophilic conditions and was compared with the theoretical methane potential that was expected from the analyses of different organic fractions of the two wastes. The obtained results indicated that there was approximately a 30% of biogas potential without recovering when the waste sludge was treated in the anaerobic digester. The theoretical and practical methane potential of the stabilized sludge, 0.16 L CH4 g VS–1 and 0.33 L CH4 g VS–1 respectively, showed that there were still organic fractions in the stabilized sludge that could be anaerobically degraded. That means that it is possible to enhance the methane production of the anaerobic digester of a conventional wastewater treatment plant by changing some operational conditions, for instance, the hydraulic retention time.
Diamagnetic Anisotropy Derived from the Hydrogen Bond

The diamagnetic anisotropy (Δχ)DIA of ammonium dihydrogen phosphate ADP, potassium dihydrogen phosphate KDP and gypsum was obtained for the purpose of estimating the contribution of a single hydrogen bond to the (Δχ)DIA values. The field-induced harmonic oscillation method was used to measure the small anisotropies on the order of 10-10 emu/g. The (Δχ)DIA values obtained between two magnetic principal axes for CaSO4 2H2O were 1.7×10-6 emu/mol [χ1-χ2 axes], 1.2×10-6 emu/mol [χ1-χ3 axes] and 0.4×10-6 emu/mol [χ2-χ3 axes]. For KDP, the value was 1.1×10-9 emu/g [a-c axes], and for ADP it was 1.2×10-6 emu/g [a-c axes]. The measured anisotropy was assigned to the individual chemical bonds, the (Δχ)DIA values of a single hydrogen bond being estimated to be 0.7×10-6 emu/mol.
The work functions of copper, silver and aluminium

The work functions of surfaces of copper, silver and aluminium, produced by the deposition of thin films of the metal from the vapour on to previously well-aged tungsten surfaces, have been found to be: 4·61 ± 0·04, 4·35 ± 0·05 and 4·25 ± 0·05 eV respectively. These values are based on measurements of the contact difference of potential, between these metals and tungsten, which have been made by the retarding potential method. The conditions which have to be satisfied if reliable results are to be obtained with this method are discussed and the construction of an efficient low-velocity electron gun is described.
Bulk and Surface Simulation Studies of La1-xCaxMnO3

The structural properties of La1-xCaxMnO3 are investigated by employing bulk and surface simulation techniques. The potential parameters reproduce the crystal structures of both end compositions, giving good agreement with experimental data. The calculated variation of the lattice parameters with Ca concentration also agrees with experimental values. Our calculations predict the formation of a solid solution and that, at very low temperatures and near x = 1/2, the cations preferentially order on both A and B sites. The driving mechanism for cation ordering arises from both the coulomb and ion-size terms, with the relative proportions depending on composition. However, at temperatures where high-temperature synthesis normally occurs, the ordering of the cations is random. Surface energies are calculated for (010) and (110) surfaces for the end compositions: in LaMnO3, Mn-terminated layers are more stable, whereas Ca-terminated layers are found to be more stable for the CaMnO3 system. It is proposed that t.
Devulcanization of nitrile butadiene rubber in nitrobenzene

Sulfur-crosslinked nitrile butadiene rubber (s-NBR) was found to be devulcanized when it was heated with nitrobenzene at 200°C for 3 h. The tetrahydrofuran (THF)-soluble fraction from s-NBR heated with nitrobenzene was purified by reprecipitation with THF/n-hexane, chloroform/n-hexane, and THF/n-hexane systems and was then characterized by means of Fourier transform infrared (FTIR) spectroscopy, 1H-NMR, gel permeation chromatography, dynamic thermogravimetry/differential thermal analysis (DTA), and differential scanning calorimetry (DSC). FTIR and 1H-NMR results revealed that the THF-soluble fraction contained aromatic rings derived from nitrobenzene. Furthermore, the molecular weight of the THF-soluble fraction was much lower than that of the parent noncrosslinked poly(acrylonitrile-co-butadiene). Although the weight loss of THF-soluble fraction began at a lower temperature than that of the nonheated original nitrile butadiene rubber, the residual weight at 700°C tended to be higher for the former. This tendency became more marked with increasing time of heat treatment with nitrobenzene. The DSC-determined glass-transition temperature of the THF-soluble fraction was higher than that of the original s-NBR. To elucidate the devulcanization mechanism, we investigated two types of model reactions; one was the reaction of diphenyl disulfide with nitrobenzene, and the other was the reaction of polybutadiene with nitrobenzene. The former reaction, carried out at 250°C in diphenyl ether, yielded diphenyl sulfide with a loss of diphenyl disulfide and nitrobenzene. The use of a higher molar ratio of nitrobenzene to diphenyl disulfide resulted in a depression of diphenyl sulfide formation. The reaction of p-chloronitrobenzene with diphenyl disulfide also gave diphenyl sulfide. The reaction of polybutadiene with nitrobenzene at 200°C resulted in the backbone scission of the polymer. The THF-soluble solid product of the latter model reaction was found by FTIR and 1H-NMR to contain aromatic rings derived from nitrobenzene. The devulcanization mechanism is discussed on the basis of a comparison of the results of the model reactions with those of the s-NBR devulcanization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3342–3353, 2004
Web Tools for Predicting Metal Binding Sites in Proteins

Approximately one third of proteins bind metal ions for stability and/or enzymatic function. However, on a structural level, only a small fraction of binding sites have been resolved. Metal binding site predictions can serve as a first step in putative function assignment for many unannotated proteins. Sequence based and structure based methods for metal binding site predictions are reviewed here. The CHED and SeqCHED methods of prediction from apo protein structures and translated gene sequences, respectively, are described in detail, including their web server applications. The relevance of SeqCHED to the analysis of single nucleotide polymorphisms (SNPs) associated with disease related metal binding sites is illustrated.
Structure of Microphase-Separated Silica/Siloxane Molecular Composites

The structure of several classes of silica/siloxane molecular composites is investigated using small-angle x-ray and neutron scattering. These filled elastomers can be prepared through different synthethic protocols leading to a range of fillers including particulates with both rough and smooth surfaces, particulates with dispersed interfaces, and polymeric networks. We also find examples of bicontinuous filler phases that we attribute to phase separation via spinodal decomposition. In-situ kinetic studies of particulate fillers show that the precipitate does not develop by conventional nucleation-and-growth. We see no evidence of growth by ripening whereby large particles grow by consumption of small particles. Rather, there appears to be a limiting size set by the elastomer network itself. Phase separation develops by continuous nucleation of particles and subsequent growth to the limiting size. We also briefly report studies of polymer-toughened glasses. In this case, we find no obvious correlation between organic content and structure.
Defects, Solvent Quality, and Photonic Response in Lamellar Block Copolymer Gels

Stimuli-responsive photonic gels are made from the lamellar block copolymer (BCP) poly(styrene-b-2-vinylpyridine) (PS–P2VP), where the photonic responses are triggered by swelling/deswelling of the P2VP block with a selective solvent. When compared to isotropic swelling in chemically cross-linked homopolymer gels, the P2VP block in the lamellar BCP shows significantly lower degrees of swelling in alcohol–water cosolvents. The glassy PS layers completely constrain the lateral expansion of the P2VP gel layers and the dislocation defect network that develops during BCP self-assembly provides a counter force to vertical swelling. A model based on Flory–Huggins mixing and dislocation network strain energy is proposed to capture the swelling behavior of the BCP and is then used to estimate the dislocation network density in the lamellar BCP. This work establishes the quantitative relationship between the reflective color of the photonic gel, the effective χ parameter of the swellable block and the solvent, and .