Isobaric vapor–liquid equilibria of binary system ethyl acetate + ethyl benzene + lithium bromide

The isobaric vapor–liquid equilibrium (VLE) behaviors for binary system, ethyl acetate + ethyl benzene, and ethyl acetate + ethyl benzene + LiBr (at saturation) were studied at the local ambient pressure (707 ± 1 mmHg). Equilibrium still was used where both liquid and vapor were continuously circulated. The experimental results showed that salt-free ethyl acetate + ethyl benzene system does not form an azeotrope point. The experimental results for ethyl acetate + ethyl benzene system were in a very good agreement with the predicted results using UNIFAC, UNIQUAC, NRTL, and Wilson models. Adding LiBr, as a salt, did show slight effects on the VLE behavior of ethyl acetate + ethyl benzene system.     

A graphene oxide facilitated a highly porous and effective antibacterial regenerated cellulose membrane containing stabilized silver nanoparticles

Regenerated nanocomposite cellulose membranes embedded with silver nanoparticles (AgNP) and AgNP-graphene oxide (AgGO) were prepared in this study. The as-synthesized AgNP and AgGO were added respectively to a cellulose solution that was prepared by dissolving cellulose in a precooled NaOH/urea (NU) solvent. The solution mixtures were further regenerated into nanocomposite membranes through coagulation in an acidic solution. UV-Vis and TEM results revealed the improved stability of the AgGO compared to that of the AgNP in NU solutions. As revealed by FESEM, the AgGO nanocomposite membrane possessed a more porous structure than a membrane containing AgNP. Antibacterial tests demonstrated that the cellulose membrane of AgGO inhibited the growth of both Staphylococcus aureus and Escherichia coli more effectively than the AgNP nanocomposite membrane, with a lower concentration of AgGO. This work provides a proven and effective method to prepare novel functional cellulose membranes with antibacterial properties, thus broadening the applications of cellulose.     

Identification and quantification of natural isoxazolinone compounds by capillary zone electrophoresis.

A capillary zone electrophoresis (CZE) method that is specific, simple, rapid and also cheap was developed to analyse some natural UV-absorbing isoxazolinone compounds with toxic potential present in legume seedlings. The six most common natural isoxazolinone compounds were separated within 10 min with 25 mM potassium phosphate (pH 7.5) containing 8% 1-propanol as running buffer. A 60 cm coated fused-silica capillary (52.6 cm effective length x 75 microm I.D.), with an electric field of 375 V/cm at 30 degrees C was used. The limit of detection ranged from 0.01 mM (3.0 microg/ml) to 0.03 mM (7.7 microg/ml). Linearity between peak areas and concentrations ranging from 0.05 mM to 1.75 mM were determined for each isoxazolinone. The correlation coefficient was 0.9954 or greater. Both relative migration time and peak area were reproducible. The RSD of relative migration time is between 0.44 and 1.94% and RSD of peak area is between 1.26 and 6.86%. The concentrations of isoxazolinones in Lathyrus odoratus and L. sativus seedlings obtained by CZE were in agreement with the previous results from HPLC.     

μ‐1,4‐Benzenedicarboxylato‐bis[trans‐aqua(1,4,8,11‐tetraazacyclotetradecane)nickel(II)] diperchlorate forms a three‐dimensional hydrogen‐bonded framework

The title compound, [Ni₂(C₈H₄O₄)(C₁₀H₂₄N₄)₂(H₂O)₂](ClO₄)₂, contains two independent octahedral Ni^II centres with trans‐NiN₄O₂ chromophores. The bridging benzene­dicarboxyl­ate ligand is bonded to the two Ni atoms, each via one O atom of each carboxyl­ate, while the other O atom participates in an intramolecular N—H?O hydrogen bond, forming an S(6) motif. The cations are linked to the perchlorate anions via O—H?O and N—H?O hydrogen bonds [O?O 2.904 (6) and 2.898 (6) Å; O—H?O 158 (6) and 165 (6)°; N?O 3.175 (7) and 3.116 (7) Å; N—H?O 168 and 166°] to form molecular ladders. These ladders are linked by further O—H?O and N—H?O hydrogen bonds [O?O 2.717 (6) and 2.730 (5) Å; O—H?O 170 (4) and 163 (6)°; N?O 3.373 (7) and 3.253 (7) Å; N—H?O 163 and 167°] to form a continuous three‐dimensional framework. The perchlorate anions both participate in three hydrogen bonds, and both are thus fully ordered.     

Approximation par la méthode des éléments finis de la formulation en domaine régulier de problèmes de fissures

The discretization by various mixed finite element methods of a new variational formulation of crack problems is considered. The new formulation, called the smooth domain method, is derived for crack problems in the case of a simplified model of an elastic membrane. Inequality type boundary conditions are prescribed at the crack faces. The resulting model takes the form of an unilateral contact problem on the crack. The mathematical analysis for the method leads to optimal convergence rates, as given in this Note. To cite this article: Z. Belhachmi et al., C. R. Acad. Sci. Paris, Ser. I 338 (2004).     

Hydromagnetic fluctuating flow of a couple stress fluid through a porous medium

The equations of a polar fluid of hydromagnetic fluctuating through a porous medium are cast into matrix form using the state space and Laplace transform techniques the resulting formlation is applied to a variety of problems. The solution to a problem of an electrically conducting polar fluid in the presence of a transverse magnetic field and to a probem for the flow between two parallel fixed plates is obtained. The inversion of the Laplace transforms, is carried out using a numerical approach. Numerical results for the velocity, angular velocity distribution and the induced magnetic field are given and illustrated graphically for each problems.     

ON A BI-HARMONIC EQUATION INVOLVING CRITICAL EXPONENT: EXISTENCE AND MULTIPLICITY RESULTS

In this paper, we consider the problem of existence as well as multiplicity results for a bi-harmonic equation under the Navier boundary conditions: △2 u = K(x)u p , u > 0 in Ω , △u = u = 0 on Ω , where Ω is a smooth domain in R n , n 5, and p + 1 = 2 n n 4 is the critical Sobolev exponent. We obtain highlightly a new criterion of existence, which provides existence results for a dense subset of positive functions, and generalizes Bahri-Coron type criterion in dimension six. Our argument gives also estimates on the Morse index of the obtained solutions and extends some known results. Moreover, it provides, for generic K, Morse inequalities at infinity, which delivers lower bounds for the number of solutions. As further applications of this Morse theoretical approach, we prove more existence results.     

Pharmacoinformatics and UPLC-QTOF/ESI-MS-Based Phytochemical Screening of Combretum indicum against Oxidative Stress and Alloxan-Induced Diabetes in Long–Evans Rats

This research investigated a UPLC-QTOF/ESI-MS-based phytochemical profiling of Combretum indicum leaf extract (CILEx), and explored its in vitro antioxidant and in vivo antidiabetic effects in a Long–Evans rat model. After a one-week intervention, the animals’ blood glucose, lipid profile, and pancreatic architectures were evaluated. UPLC-QTOF/ESI-MS fragmentation of CILEx and its eight docking-guided compounds were further dissected to evaluate their roles using bioinformatics-based network pharmacological tools. Results showed a very promising antioxidative effect of CILEx. Both doses of CILEx were found to significantly (p < 0.05) reduce blood glucose, low-density lipoprotein (LDL), and total cholesterol (TC), and increase high-density lipoprotein (HDL). Pancreatic tissue architectures were much improved compared to the diabetic control group. A computational approach revealed that schizonepetoside E, melianol, leucodelphinidin, and arbutin were highly suitable for further therapeutic assessment. Arbutin, in a Gene Ontology and PPI network study, evolved as the most prospective constituent for 203 target proteins of 48 KEGG pathways regulating immune modulation and insulin secretion to control diabetes. The fragmentation mechanisms of the compounds are consistent with the obtained effects for CILEx. Results show that the natural compounds from CILEx could exert potential antidiabetic effects through in vivo and computational study.