Miracle-dz/UniFAR-FTUs huggingface dataset:
A study of Yb0.2Co4Sb12–AgSbTe2 nanocomposites: simultaneous enhancement of all three thermoelectric properties

The single-filled skutterudite Yb0.2Co4Sb12 has been long known as a promising bulk thermoelectric material. In this work, we adopted a melting–milling–hot pressing procedure to prepare nanocomposites that consist of a micrometer-grained Yb0.2Co4Sb12 matrix and well-dispersed AgSbTe2 nanoinclusions on the matrix grain boundaries. Different weight percentages of AgSbTe2 inclusions were added to optimize the thermoelectric performance. We found that the addition of AgSbTe2 nanoinclusions systematically and simultaneously optimized the otherwise adversely inter-dependent electrical conductivity, Seebeck coefficient and thermal conductivity. In particular, the significantly enhanced carrier mobility led to a ∼3-fold reduction of the electrical resistivity. Meanwhile the absolute value of Seebeck coefficient was enhanced via the energy filtering effect at the matrix–nanoinclusion interfaces. Moreover there is a topological crossover of the AgSbTe2 inclusions from isolated nanoparticles to a nano-plating or nano-coating between 6 wt% and 8 wt% of nanoinclusions. Above the crossover, further addition of nanoinclusions degraded the Seebeck coefficient and the electrical conductivity. Meanwhile, the addition of nanoinclusions generally reduced the lattice thermal conductivity. As a result, the power factor of the 6 wt% sample was ∼7 times larger than that of the nanoinclusion-free sample, yielding a room temperature figure of merit ZT ∼ 0.51.
Enzymes in neoteric solvents: From one-phase to multiphase systems

Biphasic systems based on neoteric solvents, e.g. ionic liquids (ILs), supercritical carbon dioxide (scCO2), fluorous solvents (FSs) and liquid polymers (LPs), represent interesting alternatives to organic solvents for designing continuous clean biotransformations methods in non-aqueous environments that directly provide pure products. The classical advantages of scCO2– its ability to extract, dissolve and transport chemicals – are complemented by the high catalytic efficiency of enzymes in liquid neoteric solvents (e.g. ILs, LPs or FSs). Enzyme behaviour in scCO2 and ILs, as well as the phase behaviour of ILs/scCO2, are key parameters for carrying out integral green bioprocesses in continuous operation. Experimental approaches, reactor designs and results are discussed in this Critical review.
BLOCK STRUCTURE IN ALGINIC ACID FROM LESSONIA VADOSA (LAMINARIALES, PHAEOPHYTA)

Alkaline extraction of Lessonia vadosa blades collected in Fuerte Bulnes (southern Chile) afforded sodium alginate in 14.5% yield. Partial acid hydrolysis of the sodium alginate gave three fractions which were characterised by one- and two-dimensional nuclear magnetic resonance techniques. Fraction 1 (17.8 % yield) showed to be mainly composed of alternate heteropolymeric block (MG) and in minor proportions of polymannuronic sequences. Analysis of 13C NMR and 2D HSQC spectra indicated that Fraction 2 (64.5% yield) is a polymannuronic enriched fraction. The minor amount of guluronic acid residues in this fraction showed by 2D 1H/1H NOESY NMR spectrum to be present in a 1→4 homopolyguluronic sequence; moreover, the interresidue correlation data indicated that MG blocks were not present. Results are in agreement with data obtained by FT-IR spectroscopy in the solid state. Full assignments of 1H and 13C signals in the NMR spectra indicated that Fraction 3 (17.7%) presented a regular homopolyguluronic block structure
Distribution of cation exchange capacity between organic matter and mineral fractions in acid forest soils (Vosges mountains, France)

Summary The cation exchange capacity (CEC) of 18 samples (<2 mm) of five acid soils developed on granite or gneiss was measured before and after H2O2 treatment from pH-unbuffered extraction solution (1 N KCl). The pH in water of the soils ranged from 3.4–4.7. The samples were separated into seven fractions (<2 μm, 2–20 μm, 20–50 μm, 0.05–0.2 mm, 0.2–0.5 mm, 0.5–1 mm and 1–2 mm) and the CEC of each measured. Thus the contribution of each size fraction and of organic matter to the CEC was obtained. From CEC measurements on the different fractions and particle size distribution data, a balance calculation was carried out to verify the methodology. According to the hypotheses used and soil characteristics, the CEC of organic matter was found to vary from 35 to 165 cmolc kg−1 and so represented from 10 to 85% of the total soil CEC in the upper soil horizons. In these sandy soils developed on granite or gneiss which were frequently affected by hydrothermal alteration, the CEC of silt and sand fractions was large. It can represent from 35 to 80% of the total soil mineral CEC. The specific contribution of the 0.2–2 mm fraction can reach 50% of the total soil mineral CEC with values ranging from 0.5–5.2 cmolc kg−1. The mineralogical description showed that hydrothermal white micas and neoformed smectites (precipitated during weathering) were present in all the fractions even in the coarsest ones. In some subsoils, albite grains containing smectite have a CEC as large as 21 cmolc kg−1. This study shows that the CEC of acid soils was not always located in the organic matter and in the clay fraction. The sand fraction can contribute substantially to the soil CEC. Resume La capacite d'echange cationique (CEC) de la terre fine ( 2 μn) est importante. Elle represente toujours plus de 35% de la CEC des fractions ‘minerales’ et peut atteindre 80%. La CEC de la fraction la plus grossiere (0.2–2 mm) est comprise entre 0.5 et 5.2 cmolc kg-1 et peut representer jusqu'a 50% de la CEC des fractions ‘minerales’. L'etude mineralogique de ces fractions montre qu'elles contiennent des micas blancs d'origine hydrothermale, et parfois des smectites supergenes. Dans certaines arenes des sols etudies, les grains d'albite contenant des smectites peuvent presenter une valeur de CEC de 21 cmolc kg-1. Ce travail montre donc que la CEC des sols acides n'est pas toujours essentiellement localisee sur la matiee organique et sur la fraction argileuse. Les fractions minerales grossieres peuvent contribuer pour une part importante a la CEC totale.
Arsenobetaine is a significant arsenical constituent of the red Antarctic alga Phyllophora antarctica

Environmental context. Although arsenic occurs in marine animals at high concentrations, the pathways by which it is biotransformed and accumulated remain largely unknown. The observation that some species of algae can contain significant concentrations of arsenobetaine, a major marine arsenic species, is relevant to explanations of the source of this compound to marine animals and its transport through the marine food web. Abstract. Significant amounts of arsenobetaine (up to 0.80 μg As g–1 dry mass, representing 17% of the extractable arsenic) were found in the extracts of all four samples of the red alga Phyllophora antarctica collected from two sites in Antarctica (Terra Nova Bay and Cape Evans). The assignment was made with high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC-ICPMS) based on exact cochromatography with a standard compound with two chromatographic systems (cation-exchange and ion-pairing reversed-phase), each run under two sets of mobile phase conditions. Particular care was taken during sample preparation to ensure that the arsenobetaine was of algal origin and did not result from epiphytes associated with the alga. Another red alga, Iridaea cordata, collected from Terra Nova Bay, did not contain detectable concentrations of arsenobetaine. For both algal species, the majority of the extractable arsenic was present as arsenosugars. Confirmation that marine algae can contain significant amounts of arsenobetaine allows a simpler explanation for the widespread occurrence of this arsenical in marine animals.
Numerical study of pipeline restart of weakly compressible irreversibly thixotropic waxy crude oils

A 3-D axisymmetric model is developed to predict pressure wave propagation processes during gelled waxy oil pipeline restart operations. A finite volume method is implemented on a staggered grid. An iterative predictor-corrector algorithm provides solutions to the combined parabolic-hyperbolic set of governing equations. A new shear-history-dependent thixotropic rheology model is proposed for pressure wave propagation computations. Moderate Reynolds number flows within the laminar regime are computed, demonstrating the impact of inertial effects. The results clearly illustrate the important mechanisms of pipeline restart. The nature of pressure wave propagation is governed by gel strength as well as overall fluid compressibility. Three sequential pressure wave propagation regimes are dominated by inertial, viscous, and gel degradation phenomena, respectively. The viscous and gel degradation regimes are effectively coupled by imposed deformation conditions. For initially homogenous thixotropic gels, strain tends to localize near the pipeline wall, playing a central role in assuring the pipeline restart. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2657–2671, 2015
Using Computational Fluid Dynamics To Study the Dynamic Behavior of the Continuous Mixing of Herschel-Bulkley Fluids

A continuous-flow mixer was designed and built to study the mixing of xanthan gum solution, a pseudoplastic fluid possessing yield stress. The extent of flow nonideality was quantified using a dynamic model that incorporated two parameters: channeling and fully mixed volume in the vessel. Dynamic experiments were made using the frequency-modulated random binary input of a brine solution to determine the magnitude of nonideal flow parameters. The same experiments were simulated using a computational fluid dynamics (CFD) package (Fluent 6.2). CFD flow fields were used to obtain the system dynamic response to a tracer injection applied at conditions identical to the experimental ones. The extents of channeling and effective mixed volume were determined using the CFD model and then compared with the parameters obtained experimentally. Validated CFD flow fields enabled us to effectively monitor the effect of various operating conditions on flow nonideality, to relate flow pattern and cavern dimension to flow n.
Investigation of the dynamics of matrix-assisted laser desorption/ionization ion formation using an electrostatic analyzer/time-of-flight mass spectrometer

A hybrid electrostatic analyzer/time-of-flight mass spectrometer was used to examine the matrix-assisted laser desorption/ionization (MALDI) ion kinetic energy distributions for Na + , protonated 7-hydroxy-4-methylcoumarin matrix ions and protonated bradykinin under a variety of source region accelerating electric field conditions. Broad kinetic energy distributions are observed for the three targeted ions with the ions having both positive and negative kinetic energies relative to the full acceleration potential. The positive kinetic energy ions are shown to have flight times in good agreement with flight times calculated from first principles while the flight times of the negative kinetic energy ions diverge positively from the calculated values. Analysis of the flight time shifts for the negative kinetic energy ions allows an entrainment velocity of ∼550 m s -1 for the material to be calculated. A composite picture of the dynamics of MALDI ion formation is presented which combines promptly formed protonated matrix and analyte ions with ions formed/accelerated at delayed times in an expanding, constant velocity plume of laser desorbed material.
KINEMATIC VISCOSITIES OF POLYETHYLENE GLYCOL + DEXTRAN + WATER SOLUTIONS

ABSTRACT The kinematic viscosities of aqueous polyethylene glycol and dextran and polyethylene glycol + dextran + water were measured at temperatures of 30, 50, and 70°C. Polyethylene glycol with relative molecular masses of 200 and 1000 and dextran samples with nominal molecular masses of 37 500 and 2 000 000 were used. A one-parameter Grunberg-like equation proposed earlier by one of the present authors was used for estimating the values of viscosity of polyethylene glycol + dextran + water. A disposable parameter for the temperature range was calculated as 0.96 and 1.05 for PEG 200 + dextran 37 500 + water and PEG 1000 + dextran 37 500 + water, respectively, and as 2.74 and 2.80 for PEG 200 + dextran 2 000 000 + water, and PEG 1000 + dextran 2 000 000 + water, respectively. In view of our results, the proposed model works well for systems containing polyethylene glycol and dextran with different molecular masses.
Biocatalytic Synthesis of Aromatics from D-Glucose: The Role of Transketolase

The percentage of D-glucose that microbes such as Escherichia coli convert into aromatics is one of the key considerations that will determine the long-term utility of such biocatalytic syntheses. Considerable research has focused on improving percent conversions by increasing the in vivo catalytic activity of the first enzyme involved in aromatic biosynthesis, 3-deoxy-D-arabino-heptulosonic acid 7-phosphate (DAHP) synthase. This report details a different strategy based on increasing the in vivo catalytic activity of the enzyme transketolase when DAHP synthase catalytic activity is amplified
Batch Studies of Zinc(II) Ion Adsorption onto Alginic Acid Fibres

The ability of alginic acid fibres to remove Zn(II) ions from aqueous solution was investigated by batch experiments. The effect of experimental parameters including pH, agitation time, initial Zn(II) ion concentration, temperature and biosorbent dosage on the biosorption of Zn(II) ions from aqueous solution was studied. Thermodynamic studies of Zn(II) ion biosorption demonstrated the exothermic nature of the process. Kinetic studies showed that the biosorption conformed to the pseudo-second-order and intra-particle diffusion models. The Langmuir and Freundlich isotherm models provided a good fit to the experimental data. The activation energy for the biosorption process suggested that it occurred in a physical manner. Alginic acid fibres have been demonstrated to be effective marine materials for the removal of Zn(II) ions from aqueous solution.
Melt polycondensation of L‐lactic acid with Sn(II) catalysts activated by various proton acids: A direct manufacturing route to high molecular weight Poly(L‐lactic acid)

Poly(L-lactic acid) (PLLA) was produced by the melt polycondensation of L-lactic acid. For the optimization of the reaction conditions, various catalyst systems were examined at different temperature and reaction times. It was discovered that Sn(II) catalysts activated by various proton acids can produce high molecular weight PLLA [weight-average molecular weight (Mw ) ≥ 100,000] in a relatively short reaction time (≤15 h) compared with simple Sn(II)-based catalysts (SnO, SnCl2 · 2H2O), which produce PLLA with an Mw of less than 30,000 after 20 h. The new catalyst system is also superior to the conventional systems in regard to racemization and discoloration of the resultant polymer. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1673–1679, 2000
The synthesis and the structure elucidation of N,O-diacetyl derivative of cyclic 3-hydroxymelatonin

Melatonin was subjected to an oxidation to give 3-hydroxymelatonin. All spectroscopic data for this compound were collected. Ab initio calculations for both possible configurations were performed. X-ray data on N,O-diacetyl derivative of 3-hydroxymelatonin allowed the unambigous structure determination.
Glucocorticoid-Induced Changes in Osteoblastic Cells

Glucocorticoids (GCs) are steroid hormones having a dual action with respect to differentiation and function of the bone-forming cells, osteoblasts. GCs are required for osteogenic lineage commitment and further differentiation, but at high and prolonged pharmacological dosage schedules, these drugs are harmful to mature cells leading to GC-induced osteoporosis (GIO). Despite previous studies, the exact mechanisms behind these complex effects are still not fully known. Therefore, this study was designed to characterize potential novel GC target genes in order to obtain further knowledge about the molecular mechanisms involved in the effects of GCs on bone health. During this thesis work, a new target gene for both GC and Wnt signalling pathways was identified in osteoblastic cells. Glutamine synthetase (GS) was found to be upregulated by GCs while downregulated by the Wnt pathway. Also calcitriol, i.e. active vitamin D, inhibited GS activity. GS could regulate the concentration of glutamate in osteoblastic cells thus controlling a third important signalling pathway, the glutamate signalling. We were also able to link GS to osteoblastic differentiation, and it could thus be even considered as a novel differentiation marker. Importantly, our results provide promising data for clarifying the molecular mechanisms behind the beneficial effects of therapeutic ultrasound (US) on bone healing as Wnt signalling was activated in the osteoblastic cells following US exposure. Furthermore, a novel mechanism for GCs to downregulate Wnt signalling pathway in bone was observed; Calreticulinmediated nuclear export of the complex of glucocorticoid receptor and β-catenin was involved in the GCs ability to inhibit Wnt signalling in the osteoblastic cells. GS seems to be in a central position in the interplay between GC, Wnt, and glutamate signalling pathways, and thus its regulation may be crucial for the signal cross-talk mechanisms and intercellular communication in the bone environment. Furthermore, the inhibitory effect of GCs on Wnt signalling could explain, at least partly, the potential negative influence of GCs on mature osteoblasts that may lead to GIO. In addition, activation of the Wnt signalling pathway by US provides new information for the poorly known cellular mechanisms on which its bone healing properties are based on. More profound knowledge about the molecular mechanisms involved in bone cell differentiation and function could benefit prevention or treatment of GIO, fracture healing processes, tissue engineering technology with stem cells as well as assisting in the development of bone-friendly GC pharmaceuticals. National Library of Medical Classification: QU 375, WE 200, WE 250, WK 755 Medical Subject Headings: beta Catenin; Bone and Bones; Bone Marrow Cells; Calcitriol; Calreticulin; Cell Differentiation; Glucocorticoids; Glutamate-Ammonia Ligase; Glutamic Acid; Mesenchymal Stem Cells; Osteoblasts; Osteoporosis; Receptors, Glucocorticoid; Signal Transduction; Ultrasonography; Wnt Proteins
Electronic Energy Transfer within the Hexamer Cofactor System of Bacterial Reaction Centers

Flow of excitation energy within the bacteriochlorin cofactor system of bacterial reaction centers has been studied by multicolor transient absorption spectroscopy using differently shaped excitation pulses of 30 fs, both at room temperature and at 15 K. This approach, which includes the analysis of free induction decay signals, helps to disentangle the processes of electronic dephasing, energy transfer, internal conversion, and nuclear motion, all taking place on the time scale of ∼100 fs. Part of the excitations (estimated at 80−90% at room temperature) flow via the scheme H* → B* → P+* → P-*, in which H* and B* represent excited bacteriopheophytin and bacteriochlorophyll monomers and P+* and P-* the upper and lower excited states of the bacteriochlorophyll dimer P, respectively. H* → B* takes less than 100 fs. B* → P+* (∼200 fs) energy transfer is a slower process than the internal conversion process within P* (50−100 fs) and therefore is rate limiting for P-* formation. At low temperature, electronic .
The role of oxygen in photooxidation of organic molecules on semiconductor particles

The kinetics of O 2 reduction accompanying oxidation of organic compounds on photocatalytic semiconductor particles is analyzed. The rate-controlling processes are defined and the electron reactivities are derived for two cases: A, electrons moving freely in the semiconductor particle and reacting with O 2 anywhere on its surface and B, electrons trapped at or near the surface of the semiconductor particle and transferred from the traps only to nearby O 2 molecules
THE INFLUENCE OF ORGANIC, BIO AND MINERAL ORE MIXTURE FERTILIZERS ON YIELD AND QUALITY OF TOMATO UNDER NORTH SINAI CONDITIONS

A field study was carried out during summer seasons of 2014 and 2015 at the Experimental Farm of the Faculty of Environmental Agricultural Sciences, El-Arish, Suez Canal University. It aims to study the effect of organic, bio and a mixture of natural mineral ore fertilizers on the productivity and quality of tomato fruits using local hybrid "Alisa" under sandy soil conditions using drip-irrigation system. The experiment included nine treatments as follows: T R 1 R = 5.7 ton of compost / fad. (40 kg N) + 80kg N / fad. , from ammonium sulfate (20.5% N) as control, T R 2 R = 11.4 ton of compost / fad. (80kg N), T R 3 R = 17.1 ton of compost / fad. (120kg N), T R 4 R = 11.4 ton of compost / fad. (80kg N) + 1 ton mixture of natural mineral ore / fad. , T R 5 R = 17.1 ton of compost / fad. (120kg N) + 1 ton mixture of natural mineral ore / fad. , T R 6 R = 11.4 ton of compost / fad. (80kg N) + 400 g / fad. nitrogen fixing bacteria containing (NFB) Azotobacter chroococcum , T R 7 R = 17.1 ton of compost / fad. (120kg N) + NFB, T R 8 R = 11.4 ton of compost / fad. (80kg N) + 1 ton / fad. mixture of natural mineral ore, T R 9 R =- 17.1 ton of compost / fad. , (120kg N) + 1 ton / fad. mixture of natural mineral ore + NFB. Application of 17.1 ton of compost / fad. (120 kg N/fad.) + one ton / fad. , mixture of natural mineral ore + NFB recorded the highest significant values of total fresh and dry weight, leaf area/ plant, growth attributes, photosynthetic pigments, early and total yield as well as fruit quality.
Influence of solvent and scaleup upon the hydrogenation of 4-phenyl-2-butanone

The focus of this thesis is the role of the solvent and scale-up upon rate and selectivity in heterogeneous catalysed hydrogenations, which are ubiquitous in the production of fine chemicals and pharmaceuticals. A kinetic method has been developed based on rigorous statistical methods and sensitivity analysis for the catalytic hydrogenation of 4-phenyl-2- butanone in stirred tank reactors at two different scales using Pt/TiO2 and Pt/SiO2 catalysts. In this thesis, modelling carried out for a 100 mL scale reactor was validated against experimental data supplied by Queens University Belfast (QUB). Experimental measurements of rate and selectivity and model validation at a larger 3000 mL scale were both carried out as part of this study. The models were evaluated over a wide range of operational conditions at both scales for Pt/TiO2 catalyst, and by using a systematic kinetic methodology it was possible to identify the dominant reaction route, derive physiochemically meaningful kinetic data and a reduced kinetic model that was applicable to the scale-up. Comprehensive kinetic analysis made it possible to gain some insight into the shift in reaction mechanism upon scale-up. Kinetic investigation of solvent effects was also carried out at the 100 mL scale for a range of solvents (protic, aprotic polar, apolar, ethers, and halogens) and both catalysts, again tested against experimental data supplied by QUB. The dominant effects of solvent on rate and selectivity of the chosen reaction system were identified as the degree of active site availability imposed by competitive adsorption of solvent on catalyst and the extent of which the solvents assist the product desorption from catalyst surface. The solvent effects upon scale-up give the remarkable result of a significant shift in the selectivity of the catalyst towards phenyl ring and ketone hydrogenation groups of 4-phenyl-2-butanone.