Miracle-dz/UniFAR-FTUs huggingface dataset:
Fabrication and Characterization of Jute Fiber Reinforced Low Density Polyethylene Based Composites: Effects of Chemical Treatment

Jute fiber reinforced low density polyethylene (LDPE) composites (10-30% fiber, by weight) are prepared by compression molding. Tensile strength (TS), bending strength (BS) and bending elongation (BE) of the composites are increased over LDPE. Jute fiber is treated with monomer (2-hydroxyethyl methacrylate, HEMA) along with two different initiators in methanol solvent. Jute fibers are soaked with 10% HEMA+2% Irgacure-184 (F1-Formulation) and 3% HEMA+2% benzol peroxide (F2-Formulation) and dried at 80oC for 2 hours then composites are fabricated by compression molding. It is found that due to chemical treatment of the jute fibers, a significant improvement of the mechanical properties of the composites are happened (56% TS, 30% BS and 35% BE) compared to the LDPE. 3%HEMA+2% benzol peroxide treated jute composites found better mechanical properties compared to 10%HEMA+2% Irgacure-184 treated jute composites. Dielectric constant and loss tangent of the composites are increased with increasing temperature up to a transition temperature and then decreased, finally reached to plateau. Scanning Electron Microscopic (SEM) analysis of the fracture side of the composites are carried out and supported better fiber-matrix adhesion due to the chemical treatment. Keywords: Jute fiber; Polyethylene; Composite; Tensile strength; Bending strength; Dielectric constant; Loss tangent. © 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi:10.3329/jsr.v3i2. 6763 J. Sci. Res. 3 (2), 249-259 (2011)
Nonmetabolic Reduction of Cr(VI) by Bacterial Surfaces Under Nutrient-Absent Conditions

We have measured the ability of nonmetabolizing cells of the bacterial species Bacillus subtilis, Sporosarcina ureae , and Shewanella putrefaciens to reduce aqueous Cr(VI) to Cr(III) in the absence of externally supplied electron donors. Each species can remove significant amounts of Cr(VI) from solution, and the Cr(VI) reduction rate is strongly dependent on solution pH. The fastest reduction rates occur under acidic conditions, with decreasing rates with increasing pH. XANES data demonstrate that Cr(VI) reduction to Cr(III) occurs within the experimental systems. Control experiments indicate that the Cr removal is not a purely adsorptive process. Reduction appears to occur at the cell wall, and is not coupled to the oxidation of bacterial organic exudates. Detailed kinetic data suggest that the reduction involves at least a two-stage process, involving an initial rapid removal mechanism followed by a slower process that follows first-order reaction kinetics. Due to the prevalence of nonmetabolizing cells and cell wall fragments in soils and deeper geologic environments, our results suggest that the observed nonmetabolic reduction of Cr(VI) to Cr(III) may significantly affect the environmental distribution of Cr in bacteria-bearing systems.
Electronegativity Versus Lone Pair Shape: A Comparative Study of Phosphaferrocenes and Azaferrocenes

The electron localization function (ELF), calculated at the DFT/B3LYP level of theory, has been used to analyze various phosphaferrocenes and azaferrocenes. The analysis of the bonding situation and electronic structure in the complexes reveals the importance of the shape of the heteroelement lone pair. Thus, the electron-withdrawing capability of the heteroatom-substituted ring is not only a consequence of electronegativity but also a result of the extension of the lone pair. Our data allow a model of the electrophilic reactivity of these complexes to be proposed.
Characterization of Mineral Building Materials by Mercury‐Intrusion Porosimetry

Mineral building materials are generally heterogeneous and porous solids. Their engineering properties are closely associated with their porosity and pore‐size distribution, which can be studied by mercury intrusion. The entire pore‐size distribution curves are used to determine changes in the pore structure of a material class in a qualitative way. Certain parameters derived from pore‐size distributions can be correlated to engineering properties. These key values are applied as criteria to evaluate the quality and durability of a building material. However, because of the heterogeneity of natural and artificial building materials and the influence of moisture content on their pore structure the results are strongly affected by preparation conditions such as sampling and drying. A correct analysis requires a knowledge of these effects. The paper describes the use of mercury porosimetry to study mineral building materials such as cementitious materials, bricks, and renderings. Furthermore, the influence of preparation effects on the precision of measurements is discussed.
High speed world level finite field multipliers in F2m

Finite fields have important applications in number theory, algebraic geometry, Galois theory, cryptography, and coding theory. Recently, the use of finite field arithmetic in the area of cryptography has increasingly gained importance. Elliptic curve and El-Gamal cryptosystems are two important examples of public key cryptosystems widely used today based on finite field arithmetic. Research in this area is moving toward finding new architectures to implement the arithmetic operations more efficiently. Two types of finite fields are commonly used in practice, prime field GF(p) and the binary extension field GF(2). The binary extension fields are attractive for high speed cryptography applications since they are suitable for hardware implementations. Hardware implementation of finite field multipliers can usually be categorized into three categories: bit-serial, bit-parallel, and word-level architectures. The word-level multipliers provide architectural flexibility and trade-off between the performance and limitations of VLSI implementation and I/O ports, thus it is of more practical significance. In this work, different word level architectures for multiplication using binary field are proposed. It has been shown that the proposed architectures are more efficient compared to similar proposals considering area/delay complexities as a measure of performance. Practical size multipliers for cryptography applications have been realized in hardware using
A convenient crosslinking method for sulfonated poly(ether ether ketone) membranes via friedel–crafts reaction using 1,6‐dibromohexane and aluminum trichloride

In this study, sulfonated poly(ether ether ketone) (SPEEK) was very efficiently crosslinked via a Friedel–Craft reaction using 1,6-dibromohexane and AlCl3. The resulting crosslinked SPEEK (c-SPEEK) membranes exhibited improved dimensional stability, thermal and chemical stability, and mechanical strength with slight reduction in the elongation. The methanol permeability was reduced by approximately two orders of magnitude by the crosslinking reaction. The proton conductivities of c-SPEEK membranes were greater than Nafion-212 in the temperature range of 30–90°C. Overall, this new crosslinking method can be conveniently and efficiently applicable to most aromatic hydrocarbon polymer membranes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40695.
Iodo­triphenyl­tin(IV): a monoclinic polymorph

A monoclinic polymorph of the title compound, [Sn(C6H5)3I], complements the previously reported triclinic variant [Ng (1995). Acta Cryst. C51, 629–631; Simard & Wharf (1994). Acta Cryst. C50, 397–403]. There are two molecules in the asymmetric unit; in both cases, the Sn atom adopts a distorted SnIC3 tetra­hedral environment.
Accurate Evaluation of Stopping and Straggling Mean Excitation Energies for N, O, H2, N2, O2, NO, NH3, H2 O, and N2 O Using Dipole Oscillator Strength Distributions: A Test of the Validity of Bragg's Rule

Accurate values of the mean excitation energy I/sub 0/ (occurring in the Bethe stopping cross section equation for fast charged particles) and the dipole oscillator strength sum S/sub 1/ and mean excitation energy I/sub 1/ (appearing in the equation for straggling given by Fano) have been determined for N, O, H/sub 2/, O/sub 2/, O/sub 2/, NH/sub 3/, H/sub 2/O, NO, and N/sub 2/O using dipole oscillator strength distributions. For energies for which the Bethe stopping theory is valid these results allow a quantitative test to be made of the reliability of Bragg's rule and of the analogous additivity rule for straggling. Difficulties arising from problems associated with the use of experimental stopping cross sections and the treatment of shell corrections, that have introduced uncertainty in previous studies of Bragg's rule, are avoided in the present work. Using the accurate results obtained for H/sub 2/, N/sub 2/, and O/sub 2/ as elemental values in the additivity relations, the additivity estimates of S/sub 1/, I/sub 1/, and I/sub 0/ obtained for N, O, NH/sub 3/, H/sub 2/O, NO, and N/sub 2/O agree with the accurate results to within 0.4, 0.9, and 4%, respectively. On the other hand, for the H atommore » large discrepancies (20--30%) between the accurate values for S/sub 1/, I/sub 1/, and I/sub 0/ and the estimates obtained by additivity occur and are due to major modifications in the electronic wavefunction in regions close to the proton that are caused by chemical binding. For heavier atoms this effect is relatively unimportant. For H/sub 2/, N/sub 2/, and O/sub 2/ calculated Bethe stopping cross sections are compared with experimental results and are used to discuss shell corrections to the Bethe stopping cross section equation. « less
A Facile Strategy for Preparing Self‐Healing Polymer Composites by Incorporation of Cationic Catalyst‐Loaded Vegetable Fibers

A two‐component healing agent, consisting of epoxy‐loaded microcapsules and an extremely active catalyst (boron trifluoride diethyl etherate, (C2H5)2O · BF3)), is incorporated into epoxy composites to provide the latter with rapid self‐healing capability. To avoid deactivation of the catalyst during composite manufacturing, (C2H5)2O · BF3 is firstly absorbed by fibrous carriers (i.e., short sisal fibers), and then the fibers are coated with polystyrene and embedded in the epoxy matrix together with the encapsulated epoxy monomer. Because of gradual diffusion of the absorbed (C2H5)2O · BF3 from the sisal into the surrounding matrix, the catalyst is eventually distributed throughout the composites and acts as a latent hardener. Upon cracking of the composites, the epoxy monomer is released from the broken capsules, spreading over the cracked planes. As a result, polymerization, triggered by the dispersed (C2H5)2O · BF3, takes place and the damaged sites are rebonded. Since the epoxy–BF3 cure belongs to a cationic chain polymerization, the exact stoichiometric ratio of the reaction components required by other healing chemistries is no longer necessary. Only a small amount of (C2H5)2O · BF3 is sufficient to initiate very fast healing (e.g., a 76% recovery of impact strength is observed within 30 min at 20 °C).
On the mechanism for the hydrogenation of olefins on transition-metal surfaces : the chemistry of ethylene on Pt(111)

The chemistry of ethylene on Pt(111) single-crystal surfaces was chosen here to represent olefin hydrogenation reactions on transition-metal catalysts. In vaccum the hydrogenation of ethylene was proven to proceed via a stepwise incorporation of hydrogen atoms on the clean surface, but under high pressures the catalyst was shown to become covered with carbonaceous deposits soon after exposure to the reactant gases. The species that compose the strongly bonded hydrocarbon fragments were identified as ethylidyne, a C2 moiety where one carbon atom sits on a 3-fold hollow site on the surface and is single-bonded to a methyl group directly above it. In order to better understand the role of the ethylidyne layer in the hydrogenation reaction, the mechanism of the conversion of ethylene to ethylidyne was studied in some detail. Even though no simple scheme has been found to explain this surface process so far, our studies have led to the rejection of previously suggested two-step pathways involving either vinyl .
A Monte Carlo simulation study of electrostatic forces between hexagonally packed DNA double helices

The electrostatic contribution to the force between hexagonally packed B‐DNA double helices has been studied using different statistical mechanical descriptions and the Monte Carlo simulation method. The effects of small ion correlations and sizes are considered, and comparison with experimental results is made. It is found that for monovalent counterions, the mean field Poisson–Boltzmann theory can give a reasonable reproduction of the experimental data, even though the simulations show that its description of the electrostatic interaction can be qualitatively wrong. The chemical equilibrium of the ordered DNA phase with the surrounding bulk salt solution is found to be an important feature. Furthermore, the simulations show that the correlation between the ion clouds of different DNA polyions gives rise to a significant attractive contribution to the interaction when divalent cations are present. It is suggested that this electrostatic attraction is an important driving force for the experimentally obse.
Epoxy Matrix Membrane Potentiometric Sensor Based on Zirconium Titanium Phosphate Ion Exchanger for Flow Injection Analysis of Nitrite

Preparation, characterization, origin of response and applications of a potentiometric sensor based on the use of a zirconium titanium phosphate (ZTP)-epoxy membrane are described. Zirconium titanium phosphate (ZTP) cationic exchanger embedded in an epoxy matrix is converted into a hydrated zirconium oxide anion exchanger which responds to many anionic species. A sensor based on this exchanger exhibits near-Nernstian response for nitrite and other anions over the concentration range 10 71 ‐10 75 M. Under optimized conditions, the gas dialyzer=flow-injection system provides a throughput of ca. 60 samples per hour with a high selectivity for nitrite ion over most common anions and acidic gas releasing species. Determination of nitrite at levels as low as 5610 74 M or less in the presence of sulfite and sulfide ions is performed by using a modified carrier buffer stream (10 72 M MES, pH 5.5 containing formaldehyde and Pb 2a ). Significant advantages are offered by the ZTP-epoxy membrane based sensor including a long 1ifetime (> 2 years), excellent stability and reproducibility (ca. 1 mV), fast response time (< 30 s), wide pH working range (pH 4.5‐8), low detection limit (4610 75 M) and high thermal stability(up to 80C).
Variance reduced Brownian simulation of a bead-spring chain under steady shear flow considering hydrodynamic interaction effects

To obtain numerical estimates for the properties of a model for polymers in dilute theta solutions in its long-chain limit we follow a stochastic approach to polymer kinetic theory. The model takes into account configuration-dependent hydrodynamic interaction (HI) and simplifies to the Zimm bead-spring chain model in the case of preaveraged HI, for which parameter-free “universal ratios” such as the ratio between radius of gyration and hydrodynamic radius are known. The Chebyshev polynomial method and a variance reduction simulation technique are used to implement an efficient Brownian dynamics simulation. We resolve the full dependence of several characteristic ratios versus both chain length and hydrodynamic interaction parameter, we extrapolate their values to determine universal behaviors, and compare with analytical and experimental results.
Visible Observation of Metastable Helium Atoms Confined in an Infrared/Visible Double Resonance Trap

Using a visible probe laser exciting the 2p3P2→3d3D3 transition (λ=588 nm), we have demonstrated a visible observation of metastable He atoms magnetooptically trapped by an infrared laser resonant with the 2s3S1→2p3P2 transition (λ=1083nm). Detecting visible resonance fluorescence, only 104 atoms confined in a trap with a diameter of 1 mm have been sensitively observed even with the naked eye. It has been found that under a given condition the visible laser operates as a trapping laser and considerably extends the capture range of infrared laser detuning.
Population imaging and diffusion MRI for characterizing multiple sclerosis in the human spinal cord

L'IRM quantitative a un potentiel enorme pour fournir une valeur intrinseque et indirecte aux proprietes des tissus utiles au diagnostic, au pronostic et aux essais cliniques de la sclerose en plaques (SEP), qui est une maladie inflammatoire du systeme nerveux central. Complementaire a l’imagerie cerebrale, etudier l’impact de la maladie sur la moelle epiniere grâce a l’imagerie quantitative, en particulier l’IRM de diffusion, devient un veritable defi. L'acquisition et le traitement de ce type de donnees posent des problemes inherents en raison de la distorsion de susceptibilite, de la petite section transversale de la moelle et l’absence de reperes anatomiques visibles qui permettant d'identifier des voies ou du niveau vertebral. Dans ce contexte, nous proposons plusieurs contributions pour le traitement et l'analyse statistique de ces donnees. Tout d'abord, nous proposons de nouvelles metriques geometriques pour evaluer et comparer differentes methodes de correction de distorsion en mesurant l'alignement du modele de diffusion reconstruit avec l'axe central apparent de la moelle epiniere. Deuxiemement, en utilisant une cohorte de patients atteints de SEP et de temoins sains, nous etudions le lien entre les mesures de diffusion et la presence ou l'absence de lesion dans un niveau vertebral donne et nous montrons que nous pouvons predire ce dernier avec une bonne precision en utilisant un apprentissage lineaire multivarie. Enfin, nous montrons la faisabilite d’une etude longitudinale de l’evolution des metriques d'IRM de diffusion en realisant une etude de reproductibilite a l’aide d’un ensemble de donnees test-retest, et l’appliquons aux 2 premieres acquisitions (M0 et M12) de notre cohorte de patients.
Coarse-graining strategies in polymer solutions

We review a coarse-graining strategy (multiblob approach) for polymer solutions in which groups of monomers are mapped onto a single atom (a blob) and effective blob–blob interactions are obtained by requiring the coarse-grained model to reproduce some coarse-grained features of the zero-density isolated-chain structure. By tuning the level of coarse graining, i.e. the number of monomers to be mapped onto a single blob, the model should be adequate to explore the semidilute regime above the collapse transition, since in this case the monomer density is very small if chains are long enough. The implementation of these ideas has been previously based on a transferability hypothesis, which was not completely tested against full-monomer results (Pierleoni et al., J. Chem. Phys., 2007, 127, 171102). We study different models proposed in the past and we compare their predictions to full-monomer results for the chain structure and the thermodynamics in the range of polymer volume fractions Φ between 0 and 8. We find that the transferability assumption has a limited predictive power if a thermodynamically consistent model is required. We introduce a new tetramer model parametrized in such a way to reproduce not only zero-density intramolecular and intermolecular two-body probabilities, but also some intramolecular three-body and four-body distributions. We find that such a model correctly predicts three-chain effects, the structure and the thermodynamics up to Φ ≃ 2, a range considerably larger than that obtained with previous simpler models using zero-density potentials. Our results show the correctness of the ideas behind the multiblob approach but also that more work is needed to understand how to develop models with more effective monomers which would allow us to explore the semidilute regime at larger chain volume fractions.
Electrochemical and DFT study on the inhibition of 316L stainless steel corrosion in acidic medium by 1-(4-nitrophenyl)-5-amino-1H-tetrazole

1-(4-nitrophenyl)-5-amino-1H-tetrazole was synthesized and its inhibiting action on the corrosion of 316L stainless steel (SS) in sulfuric acid was investigated by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). In the potentiodynamic polarization measurements the values of βc had small changes with increasing inhibitor concentration, which indicated that the 1-(4-nitrophenyl)-5-amino-1H-tetrazole was adsorbed on the metal surface and the addition of the inhibitor hindered the acid attack on the SS electrode. The shift in the anodic Tafel slope βa might be attributed to the modification of the anodic dissolution process due to the inhibitor module adsorption on the active sites. The results of the investigation show that the newly synthesized compound shows excellent inhibition efficiencies against the corrosion of SS in acidic solution. The adsorption of 1-(4-nitrophenyl)-5-amino-1H-tetrazole onto the SS surface followed the Langmuir adsorption model with the free energy of adsorption ΔG0ads of −9.44 kJ mol−1. Quantum chemical calculations were employed to give further insight into the mechanism of inhibition action of 1-(4-nitrophenyl)-5-amino-1H-tetrazole.
The Component Analysis of Bottled Red Sufu Products Using near Infrared Spectroscopy

Sufu (fu-ru), a cheese-like product originating in China, is one of the most popular fermented soybean foods in China. This paper indicates the possibility of using near infrared (NIR) spectroscopy as a rapid, non-destructive method to estimate the quality attributes of sufu products. The partial least squares (PLS) method was applied to build models to predict the contents of water, salt, soluble protein and free amino nitrogen in bottled red sufu product. Both optical fibre and integrating sphere accessories were used to collect the representative reflected spectra. Multiplicative scatter correction (MSC) was used to eliminate the effect of light scatter and the first-order derivation of the spectra was used to reduce the effect of absorption of glass bottles. The coefficients of determination (R2) of the four components above were 0.96, 0.98, 0.94 and 0.94, respectively using an integrating sphere, and 0.92, 0.98, 0.96 and 0.92, respectively using an optical fibre. The root mean square errors of prediction (RMSEP) of those were 0.99, 0.21, 0.49 and 0.033%, respectively using an integrating sphere and 1.63, 0.28, 0.34 and 0.041%, respectively when using an optical fibre. The correlations (R2) between the components of sufu blocks and those of the surrounding dressing mixture had been found to be 0.18 for water, 0.24 for soluble protein, 0.92 for free amino nitrogen and 0.89 for salt. These coefficients would be applicable for potential on-line analysis. The preliminary results of those models indicated that NIR spectroscopy has a potentially useful role in the measurement of the component content of sufu samples.
Current developments in clinical sample preconcentration prior to elemental analysis by atomic spectrometry: a comprehensive literature review

Sample preconcentration is important for metal analysis in complex clinical matrices due to the low concentration of analytes and high salt content. The limited amount of sample available also increases the challenges of extraction and determination of the analytes. In spite of the increase in sensitivity of instruments, such ultra-trace levels of the metals are still difficult to determine accurately. Researchers have adopted various strategies to improve the efficiency and selectivity of the extraction. The use of chemicals and time for analysis can also be reduced by scaling down the analysis to the micro-level. This review discusses four aspects of the recent development in metal preconcentration in clinical samples, namely the use of ionic liquids (ILs) in extraction, sorption by nanomaterials, preconcentration using surfactants, and automation. The publications reviewed cover the period between 2008 to late 2013.