Miracle-dz/UniFAR-FTUs huggingface dataset:
Polypeptide chain configurations in crystalline proteins

Astbury’s studies of α-keratin, and X-ray studies of crystalline haemoglobin and myoglobin by Perutz and Kendrew, agree in indicating some form of folded polypeptide chain which has a repeat distance of about 5·1 Å, with three amino-acid residues per repeat. In this paper a systematic survey has been made of chain models which conform to established bond lengths and angles, and which are held in a folded form by N—H—O bonds. After excluding the models which depart widely from the observed repeat distance and number of residues per repeat, an attempt is made to reduce the number of possibilities still further by comparing vector diagrams of the models with Patterson projections based on the X-ray data. When this comparison is made for two-dimensional Patterson projections on a plane at right angles to the chain, the evidence favours chains of the general type proposed for a-keratin by Astbury. These chains have a dyad axis with six residues in a repeat distance of 10·2 Å, and are composed of approximately coplanar folds. As a further test, these chains are placed in the myoglobin structure, and a comparison is made between calculated and observed F values for a zone parallel to the chains; the agreement is remarkably close taking into account the omission from the calculations of the unknown effect of the side-chains. On the other hand, a study of the three-dimensional Patterson of haemoglobin shows how cautious one must be in accepting this agreement as significant. Successive portions of the rod of high vector density which has been supposed to represent the chains give widely different projections and show no evidence of a dyad axis. The evidence is still too slender for definite conclusions to be drawn, but it indicates that a further intensive study of these proteins, and in particular of myoglobin which has promising features of simplicity, may lead to a determination of the chain structure.
The effect of strained confinement layers in InP self-assembled quantum dot material

We investigated a series of self-assembled InP quantum dot structures. The Ga concentrations of the GaxIn(1−x)P upper confining quantum well layers were varied from x = 0.43 to x = 0.58, centering on a strain compensated structure. All were grown on a (Al0.3Ga0.7)0.52In0. 48P lower confinement layer. Across this range of composition the dot emission wavelength changed approximately linearly with the Ga fraction. Of the compositions used, x = 0.54 gave the best defined and largest magnitude dot absorption spectrum, corresponding to the largest dot density. This resulted in the lowest overall threshold current density with a reduced threshold current temperature sensitivity at room temperature and above. These results are confirmed over two growth series.
Antibody binding to antigen-coated substrates studied with surface plasmon oscillations

We have used surface plasmon oscillations to monitor the time evolution of the adsorption of antibodies from aqueous solution onto an antigen-coated surface. The asymptotic adsorbance values (Γ f ) do not reach a maximum until the concentration of antibody in solution (C) is greater than 1 mg/mL. We interpret the shape of the Γ f vs C plot as an evolution from side-on adsorption to end-on adsorption. Our data show a characteristic time, t c , which is proportional to c -2 , indicating diffusion-limited adsorption. The value of t c is significantly greater than predicted from a diffusion-limited model. We attribute this result to a requirement that the antibodies be correctly oriented if they are to be adsorbed. A careful study of our kinetics data shows that for high concentrations we must apply theories of random sequential adsorption in addition, because the adsorbed molecules may exclude more surface area than they physically occupy.
Determination of heat transfer coefficient of air mist sprays

AbstractContinuously cast copper and nickel samples were cooled using combined air and water jet. Temperatures close to the ingot surface were measured continuously during the cooling process and the coefficient of heat transfer from the ingot to the cooling water as a function of surface temperature was calculated with the aid of a suitable mathematical model. The experiments were carried out at spray water densities from 3·4 × 10−4 to 2·72 × 10−3 m3 m−2 s−l with air pressures in the range 0·2–0·4 MPa. At lower flowrate or lower air pressure, no uniformity in droplet distribution within the spray cones could be achieved. It was found that the heat transfer coefficient when spraying an air and water mixture (air mist) is higher than that obtained for water spraying, densities being equal. As the water density is increased, the difference between the results obtained using the two methods is reduced. A formula was found by which the heat transfer coefficient can be calculated as a function of the surface t.
Mössbauer Study of Iron Fischer−Tropsch Catalysts during Activation and Synthesis

Mossbauer data indicate that activating an iron Fischer−Tropsch catalyst containing Cu, K, and kaolin with syngas for 24 h at 270 °C and 1.14 MPa produces a material that has about 60% of the iron in the form of Fe3O4 and the remainder as a mixture of χ-Fe5C2 and e‘-Fe2.2C. A similar activation with CO produces a material that contains more than 80% of the iron in the form of χ-Fe5C2 and the remainder as Fe3O4. The CO-activated catalyst exhibits a high activity, whereas the syngas-activated sample has a low activity. Moreover, the CO-activated sample converts during 50 h of synthesis to a mixture that contains more Fe3O4 (40%) and less χ-Fe5C2 (60), whereas the syngas activated sample contains about 80% χ-Fe5C2 after 50 h of exposure to synthesis gas. Thus, both catalysts underwent significant changes in the bulk composition without a parallel change in CO conversion. Another catalyst formulation, containing more Cu, much less K, and no binder, showed significantly higher syngas conversion after activatio.
Orthometallated primary amines. Part 1. Facile preparation of the first optically active cyclopalladated primary amines

Reaction of [PdCl2{NH2CH(Me)Ph}2]1 with AgCIO4(1 : 2) gave a solution containing an orthopalladated complex 2. Addition to this solution of neutral ligands or NaBr led to isolation of the complexes [Pd{C6H4[CH(Me)NH2-2]}(L2)]CIO4[L = pyridine 3a, L2= cycloocta-1,5-diene(cod)3b or 2,2′-bipyridine 3c] or [{Pd{C6H4[CH(Me)NH2-2]}(µ-Br)}2]4, respectively. Reaction of 4 with PPh3 or Tl(acac)(Hacac = acetylacetone) gave [Pd{C6H4[CH(Me)NH2-2]}Br(PPh3)]5 or [Pd{C6H4[CH(Me)NH2-2]}(acac)]6, respectively. Complexes 1, 4 and 5 can be obtained optically pure by using (R)-(+)- or (S)-(–)-α-methylbenzylamine as starting material. The solid-state crystal structures of 3b and R-5 were determined at low temperatures. In both complexes the palladium atom adopts the usual square-planar co-ordination. The major angular distortion is associated with the small bite of the chelating ligand (80.8 and 81.2°, respectively). The weaker trans influence of the cod ligand in 3b accounts for ca. 0.02 A longer Pd–N and Pd–C bonds in R-5 than in 3b. Short contacts between the perchlorate anion or bromo ligand in 3b or R-5 with the amino group (N ⋯ O 3.06 or N ⋯ Br 3.41 A, respectively) probably represent hydrogen bonds.
High-Performance Liquid Chromatography of Vitamin A Compounds

Abstract Vitamin A compounds, both natural and synthetic (collectively called retinoids), are important in the maintenance of the integrity of epithelial structures. The metabolism of natural retinoids such as retinol, retinal, retinoic acid, and retinyl esters has been studied extensively, and the metabolites have been determined by several techniques. The analytical techniques that were commonly used in the past were column chromatography, thin-layer chromatography (TLC), and gas liquid chromatography. However, the high-performance liquid chromatographic (HPLC) technique has proven to be by far the method of choice for the determination of retinoids. The determination of natural retinoids is facilitated by their inherent chemical properties, such as their intense absorption in the near ultraviolet (UV) region and the ability of several retinoids to fluoresce. These properties are often advantageous, particularly in the on-line determination of these compounds; an example is by UV in the HPLC technique.
Etude des facteurs de risque de la corrosion bactérienne des aciers au carbone induite par les bactéries anaérobies sulfurogènes

Sur site, il a ete observe que la corrosion bacterienne pouvait conduire a des percements tres rapides d'oleoducs. Il s'agit d'une corrosion par piqures foudroyante avec des vitesses de penetration d'au moins un cm/an pour un acier au carbone. Une evaluation pratique du risque associe a une contamination bacterienne est donc d'abord la prevision de corrosions aussi rapides. Schematiquement, la corrosion localisee est la stabilisation d'un couple galvanique entre une petite anode et une grande cathode l'entourant. Le courant galvanique circulant entre ces deux electrodes est la composante principale de la vitesse de corrosion a l'interieur de la piqure. La mesure de ce courant constitue une estimation du risque associe a une contamination bacterienne. En consequence, nous avons mis au point une technique electrochimique qui consiste a initier artificiellement une piqure a l'aide de deux electrodes separees. Le developpement de biofilms conducteurs a necessite la mise au point de montages specifiques eliminant tout risque d'artefact. Les facteurs de risque reliant une contamination bacterienne au developpement d'une corrosion par piqure rapide sont etudies en comparant le courant de couplage naturel circulant entre les deux electrodes. En conditions steriles, le courant de couplage est nul alors qu'il est stable en presence d'un biofilm de bacteries sulfurogenes. Qu'il s'agisse de bacteries sulfato-reductrices (bsr) ou thiosulfato-reductrices strictes (btr), la presence et l'utilisation de thiosulfate apparaissent comme un facteur de risque majeur, conduisant a des vitesses de penetration pouvant atteindre le centimetre par an. Un milieu fortement tamponne rend une telle corrosion beaucoup plus difficile. Nos experiences ont aussi montre que la formation d'un biofilm abondant est une condition necessaire de la corrosion bacterienne. Les bacteries sulfurogenes hydrogenotrophes apparaissent particulierement aptes a former un biofilm sur acier, et a entrainer par la de fortes vitesses de corrosion. L'hydrogenotropisme serait donc le facteur de risque principal en corrosion bacterienne
Nonaromatic polyimides derived from cycloaliphatic monomers

A novel tetracarboxylic dianhydride bearing a cycloaliphatic structure, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic 2,3:6,7-dianhydride (DNDA), was synthesized, and its structure was determined using X-ray crystallographic analysis. Polycondensation of DNDA or bicyclo[2.2. 1]heptane-2-endo,3-endo,5-exo,6-exo-tetracarboxylic 2,3:5,6-dianhydride (BHDA) with a cycloaliphatic diamine, bis(aminomethyl)bicyclo[2.2. 1]heptane (BBH) was carried out in HMPA. A viscous poly(amic acid) solution was obtained only when BBH was slowly added to the HMPA solution of the dianhydride, whereas the reverse adding order of the monomers resulted in precipitation due to salt formation. The poly(amic acid) solutions afforded nonaromatic polyimides as flexible and free-standing films after being cast and cured. The polyimide films were soluble in organic solvents such as DMAc and were colorless with a cutoff at wavelength shorter than 235 nm. The average refractive index of the BHDA−BBH polyim.
THE CRYSTALLIZATION OF CALCIUM SULPHATE DIHYDRATE

In this preliminary series of experiments, calcium sulphate dihydrate has been allowed to crystallize spontaneously from solutions of varying degrees of supersaturation, and induction periods and rate constants have been determined. The effect of crystal area, pH, and accelerators and retarders on this process has been examined. The degree of super-saturation has a direct effect on both the induction period and rate constant. Nucleation is affected markedly by pH. Salts having an ion in common with calcium sulphate function as accelerators. Retarders affect the induction period in proportion to their concentration, but show little, if any, effect on the rate of crystallization. The behavior of the various reagents under the conditions prevailing in these experiments is largely in accord with observations on the behavior of commercial plasters.
Vertebrate fauna of Hokarsar wetland, Kashmir

The present communication deals with the diversity, resident/migrant status, abundance and habitat used by vertebrate fauna which is dominated by Avifauna in Hokarsar wetland. During the present study a total of 8477 birds were recorded. Among them 15.09% belonged to resident community, 11.41% were summer migrants and 73.48% were the winter migrants. A total of 37 bird species belonging to 40 families under 9 orders were observed. Three species of fishes belonging to single order were procured from the wetland. The scale carp (Cyprinus carpio communis) contributed 49 Kg’s to a total yield followed by mirror carp (Cyprinus carpio specularis) which contributed 11.5 Kg’s and Schizothorax niger contributed least with 2.1 Kg. to the total fish catch. The absence of Amphibians (except few toads) from the study site was attributed to nutrient input, high turbidity, hypoxic conditions, thick mats of noxious weeds together with anthropogenic pressure and habitat destruction.
Mechanism of hydrolysis of substituted N-thiazolylcarbamate esters in OH- solutions

Substituted secondary N-thiazolylcarbamate esters and some tertiary N-methyl, N-thiazolyl carbamate esters have been synthesised and the mechanism of the OH- catalysed hydrolyses investigated. These proved to be E1cB and BAc2 respectively, and this behaviour was compared with that of other carbamates.
Three-dimensional computations of transverse hydrogen jet combustion in a supersonic airstream

A computational fluid dynamics (CFD) code is being developed to compute the mixing and combustion of hydrogen fuel in the turbulent flow fields of supersonic combustion ramjets (scramjet). The code solves the three-dimensional Reynolds time-averaged complete Navier-Stokes equations including transport equations for a four species, two reaction, global finite rate chemistry model. The code was applied to the case of transverse injection of hydrogen from a sonic circular orifice into a supersonic airstream. The equations were numerically integrated using MacCormack's explicit method, and the algebraic eddy viscosity model of Baldwin-Lomax was used to model the turbulence. In the species transport and energy equations, diffusion coefficients based on Fick's Law and an assumption of unit Lewis number were applied. Computed features of the three-dimensional flow field are depicted by static pressure, static temperature, mass fraction of species, and velocity vectors. For engineering interest, mixing and combustion parameters were examined to assess the effect of injector diameter, injected fuel pressure, fuel-air ratio, and spacing of fuel injectors. The objective of the present paper is to demonstrate the capability of the present three-dimensional spatially elliptic, CFD code for turbulent, reacting flow. Application of the code to specific supersonic combustion configurations is planned.
Modification of the biophysical water function to predict the change in soil mineral nitrogen concentration resulting from concurrent mineralization and denitrification

Georgallas, A. , Dessureault-Rompré, J., Zebarth, B. J., Burton, D. L. , Drury, C. F. and Grant, C. A. 2012. Modification of the biophysical water function to predict the change in soil mineral nitrogen concentration resulting from concurrent mineralization and denitrification. Can. J. Soil Sci. 92: 695-710. Uncertainty in soil N supply is an important limitation in making crop fertilizer N recommendations. This study modified a biophysical water function developed to predict net soil N mineralization, making it possible to consider how both N mineralization and denitrification processes affect the rate of soil mineral N accumulation. Data were from a published experiment measuring changes in soil mineral N concentration in five soils of varying texture (loamy sand to clay loam) incubated for 3 mo with or without addition of red clover residue and at two levels of compaction. The biophysical water function was effective in fitting the relationship between scaled change in the rate of soil mineral N accumulation (ΔSMN) and scaled water-filled pore space (WFPSS) across soils and treatments provided that WFPSS=1 was set to the water content at which the transition from mineralization to denitrification occurs. The water content at WFPSS=1 varied with soil type, but not residue addition or compaction treatments, and was closely related to clay content. The kD parameter, which controls the denitrification term of the function, was influenced by soil type, whereas legume residue application had no significant effect on the kD parameter despite a twofold increase in net N mineralization. The modified biophysical water function holds promise for improving estimates of soil N supply because it can predict changes in ΔSMN in response to N mineralization and denitrification processes across a wide range of soil water contents.
Diffusion theory of multidimensional activated rate processes: The role of anisotropy

We consider an anisotropic multidimensional barrier crossing problem, in the Smoluchowski (diffusion) limit. The anisotropy arises from either or both the shape of the potential energy surface and anisotropic diffusion. In such situations, the separatrix, which separates reactant and product regions of attraction, does not coincide with the ridge of the potential surface, which separates reactant and product wells, thus giving rise to a complicated time evolution. In the asymptotically long time limit, the time evolution is governed by crossing the separatrix and is exponential with a rate which may be obtained as a generalization of Kramers’ theory to the anisotropic situation. In contrast, in long, though not asymptotically long times, the time evolution is dominated by repeated crossings of the ridge, and is nonexponential. Such nonexponential time evolution has been observed in many biochemical reactions, where many degrees of freedom and anisotropic diffusion processes lead to complicated dynamical b.
Colloidal Au single-atom catalysts embedded on Pd nanoclusters

This study aims to design an efficient Au single-atom catalyst (SAC) for aerobic glucose oxidation and obtain a clear structure–activity relationship of the catalyst at the atomic level. Gold-containing bi- or multi-metallic catalysts are widely used in many important chemical processes. Engineering the electronic structure of surface atoms and downsizing the catalysts to single atoms are challengeable issues to enhance the intrinsic activity. Here we report an effective and versatile synthesis of colloidal Au/Pd SACs by using a facile successive reduction method. The prepared colloidal Au/Pd SACs exhibit a significantly improved catalytic activity (up to 17 times) for glucose oxidation over that of Au nanoclusters (NCs) with a similar size. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis and density functional theory (DFT) calculation reveal that the presence of low-coordinated and negatively charged single Au atoms on Pd clusters is responsible for the excellent catalytic performance.
Studies on drug metabolism using liquid chromatography/mass spectrometry: Comparison of three liquid chromatographic/mass spectrometric interfaces

Three ionization methods of liquid chromatography/mass spectrometry (LC/MS) [atmospheric pressure chemical ionization (APCI), thermospray (TSP) and electrospray ionization (ESI)], were characterized by investigating the relationships between sensitivities and polarities of compounds. Log P values and mass spectrometry of three hydroxymethylglutaryl-Coenzyme A (HMG-CoA) reductase inhibitors—pravastatin sodium (including its metabolites and related compounds), lovastatin and simvastatin—were measured. Their log P values ranged from −2.49 to 4.40, and in LC/MS each of the ionization methods gave different quasi-molecular ions and sensitivities. The APCI method showed a high sensitivity of several nanograms for hydrophobic compounds (log P > 2), but was not effective for hydrophilic compounds, such as glutathione conjugate. The TSP method was found to be applicable to all compounds used in this study, and was more sensitive for hydrophobic compounds. The ESI method was also applicable to all compounds (up to 20 ng), and was 10–100 times more sensitive than the other methods in the case of hydrophilic compounds. These results suggest that hydrophobicity of compounds related to efficiency of LC/MS ionization.
Molecular Simulation of Poly-α-olefin Synthetic Lubricants: Impact of Molecular Architecture on Performance Properties

Equilibrium and nonequilibrium molecular dynamics simulations are performed at constant pressure and temperature on three structurally distinct poly-α-olefin (PAO) isomers representative of a major component in synthetic motor oil basestock. In agreement with empirical observations, the temperature dependence of viscosity, as characterized by the viscosity number (VN), is reduced as the degree of branching is lowered. A molecular-level explanation for this behavior is given in terms of the energy barriers for intramolecular reorientation. Other dynamic properties, such as the diffusivity and rate of tumbling, were also computed and found to have similar dependencies on temperature as the viscosity. Based on these calculations, it appears that PAO molecules with long, widely spaced branches should yield a higher VN than those with short, closely spaced branches. The impact of shear rate on PAO properties is also investigated. High shear rates and shear-thinning increases the VN because the behavior of the .
Apparent molar heat capacities of aqueous solutions of 1-propanol, butane-1,4-diol, and hexane-1,6-diol at temperatures from 300 K to 525 K and a pressure of 28 MPa

Abstract The heat capacities of dilute aqueous solutions of 1-propanol, butane-1,4-diol, and hexane-1,6-diol have been measured at 300 K T p = 28 MPa. Extrapolation to infinite dilution gave values for C p,2 ∞ . Literature values of (∂ 2 V 2 ∞ /∂ T 2 and C p,2 ∞ at p = 0.1 MPa were used to calculate C p,2 ∞ at p = 28 MPa. After subtracting the heat capacity of a point mass, the remaining heat capacity was successfully decomposed into functional group contributions at all temperatures. The resulting values for the heat capacity contributions of the CH 2 , CH 3 , and OH groups allow reasonably accurate predictions of the heat capacities of all compounds composed of these groups in this temperature range.
Performance evaluation criteria for preparation and measurement of macro- and microfabricated ion-selective electrodes (IUPAC Technical Report)

Abstract Over the last 30 years, IUPAC published several documents with the goal of achieving standardized nomenclature and methodology for potentiometric ion-selective electrodes (ISEs). The ISE vocabulary was formulated, measurement protocols were suggested, and the selectivity coefficients were compiled. However, in light of new discoveries and experimental possibilities in the field of ISEs, some of the IUPAC recommendations have become outdated. The goal of this technical report is to direct attention to ISE practices and the striking need for updated or refined IUPAC recommendations which are consistent with the state of the art of using macro- and microfabricated planar microelectrodes. Some of these ISE practices have never been addressed by IUPAC but have gained importance with the technological and theoretical developments of recent years. In spite of its recognized importance, a generally acceptable revision of the current IUPAC recommendations is far beyond the scope of this work.