Band structure,Fermi surface,elastic,thermodynamic,and optical properties of AlZr_3,AlCu_3,and AlCu_2Zr:First-principles study

The electronic properties(Fermi surface,band structure,and density of states(DOS)) of Al-based alloys AlM_3(M=Zr and Cu) and AlCu_2Zr are investigated using the first-principles pseudopotential plane wave method within the generalized gradient approximation(GGA).The structural parameters and elastic constants are evaluated and compared with other available data.Also,the pressure dependences of mechanical properties of the compounds are studied.The temperature dependence of adiabatic bulk modulus,Debye temperature,specific heat,thermal expansion coefficient,entropy,and internal energy are all obtained for the first time through quasi-harmonic Debye model with phononic effects for T = 0 K-100 K.The parameters of optical properties(dielectric functions,refractive index,extinction coefficient,absorption spectrum,conductivity,energy-loss spectrum,and reflectivity) of the compounds are calculated and discussed for the first time.The reflectivities of the materials are quite high in the IR-visible-UV region up to ~ 15 eV,showing that they promise to be good coating materials to avoid solar heating.Some of the properties are also compared with those of the Al-based Ni_3 Al compound.     

Theoretical Study of NO Linkage Isomers in a Rhenacarborane Nitrosyl Complex

Russian Journal of Physical Chemistry A - This research demonstrates the stability of linkage isomers of [1,2-H2-3,3-(CO)2-3-X-closo-3,1,2-ReC2B9H9]; X = η1-NO, η2-NO, η1-ON by the...     

Chitosan surface modified hydrogel as a therapeutic contact lens

Therapeutic contact lenses have attracted significant attention during the last decades. In this study, we used chitosan‐conjugated poly(2‐hydroxyethyl methacrylate) (PHEMA) for contact lens application. We aimed to increase affinity of anionic drugs, which are used in treatment of eye diseases. In this regard, we evaluated delivery of the small molecule anionic drug, ascorbic acid from the chitosan‐conjugated PHEMA. Chitosan immobilization improves drug loading efficiency and induces sustained release of ascorbic acid. The chitosan modified hydrogel also reduces the biofouling of tear fluid components. Our results showed that surface modification by chitosan inhibits protein and bacterial deposition on the contact lens. Protein absorption analysis revealed that neat PHEMA adsorbed tear proteins at a density of 28.4 ± 4.4 μg/cm², whereas the chitosan‐conjugated hydrogel adsorbed tear proteins at a density of 18.5 ± 1.8 μg/cm². Moreover, the neat PHEMA bacterial adhesion had a mean CFU value of 273 ± 27. However, a significant decrease in the number of bacterial colonies was observed in the chitosan group with a CFU value of 9 ± 6.     

Novel synthesis and antitumor evaluation of polyfunctionally substituted heterocyclic compounds derived from 2-cyano-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-acetamide

The reaction of 2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene with ethyl cyanoacetate gave 2-cyano-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-acetamide. The latter was used to synthesize different heterocyclic derivatives comprising thiophene, thiazole, pyrazole, pyridine, pyrimidine, and coumarin rings. The mechanistic and synthetic pathways depended on regioselective attack and/or cyclization by the cyanoacetamido moiety in the key precursor on various chemical reagents. The competition of the reaction pathways including dipolar cyclization, dinucleophilic-bielectrophilic attack, β-attack, Gewald-type attack, and condensation reactions led to the diversity of the synthesized products. The antitumor activities of the synthesized products were studied and evaluated. Most of the compounds revealed high inhibitory effects when screened in vitro for their antiproliferative activity. Three human cancer cell lines, namely, breast adenocarcinoma (MCF-7), non-small cell lung cancer (NCI-H460) and CNS cancer (SF-268) were used in the screening tests. The simplicity of the synthetic procedures which mainly involved one-pot reactions under mild reaction conditions, the convenience of yield production and the diversity of the reactive sites in the produced systems play a valuable role for further heterocyclic transformations and further biological investigations.     

Application of response surface methodology for modelling the enzymatic assay of hydrogen peroxide by Emerson–Trinder reaction using 4-iodophenol

In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) were combined for modelling and optimizing the experimental parameters of the enzymatic Emerson–Trinder reaction, for the determination of hydrogen peroxide. This spectrophotometric indicator reaction is currently used in biotechnology for the determination of phenolic compounds (e.g. in industrial samples) and also for determination of various substrates (e.g. in clinical chemistry). Using 4-iodophenol as a hydrogen donor in this reaction, the quality of the generated second-order polynomial response model equation was checked by the kinetic assay of H₂O₂ in real samples (e.g. cosmetic and human pooled serum samples), where their resulting satisfactory analytical characteristics were reported.     

Cu/SiO2：A recyclable catalyst for the synthesis of octahydroquinazolinone

A simple and one-pot method for the synthesis of octahydroquinazolinone is reported.Cu/SiO₂ in refluxing ethanol catalyzes this three-component condensation reaction to afford the corresponding quinazolinones in good yields.     

Nanostructured Screen Printed Graphite Electrode for the Development of a Novel Electrochemical Genosensor

The aim of this work is the preparation of DNA‐sensing architectures based on gold nanoparticles (AuNPs) in conjunction with an enzyme‐amplified detection to improve the analytical properties of genosensor. In order to assess the utility of study as DNA‐sensing devices, a thiolated DNA capture probe sequence was immobilized on the gold nanoparticle modified surface. After labeling of the biotinylated hybrid with a streptavidin‐alkaline phosphatase conjugate, the electrochemical detection of the enzymatic product was performed on the surface of a disposable electrode. Two different enzymatic substrates to detect the hybridization event were studied. In the first case, the enzyme catalyzed the hydrolysis of α‐naphthyl phosphate; the product is electroactive and has been detected by means of differential pulse voltammetry (DPV). In the second one, the enzyme catalyzed the precipitation of an insoluble and insulating product on the sensing interface. In this case, the electrochemical transduction of the hybridization process was performed by electrochemical impedance spectroscopy (EIS).     

Application of nickel phosphate nanoparticles and VSB-5 in the modification of carbon paste electrode for electrocatalytic oxidation of methanol

Carbon paste electrodes were modified by nickel phosphate nanoparticles and nickel phosphate Versailles Santa Barbara-5 molecular sieves. Then, transition metal ions of Ni(II) were incorporated to the nickel phosphate by immersion of the modified electrode in a 0.1-M nickel chloride solution. The electrochemical behaviors of the modified electrodes were studied using cyclic voltammetry. These modified electrodes were used as anode for the electrocatalytic oxidation of methanol in alkaline medium. The influence of some parameters such as different molecular sieves, scan rate of potential, and methanol concentration was investigated on the anodic peak height of the methanol oxidation. The best result was obtained by nickel phosphate nanoparticles.     

Efficient iodination of aromatic compounds using potassium ferrate supported on montmorillonite

Potassium ferrate impregnated on montmorillonite is a mild,cheap,and non-toxic reagent for the iodination of phenols, including naphthol,aromatic amines,and heterocyclic substrates in fair to excellent yields by a simple isolation procedure.     

Headspace-solid phase microextraction of selenium(IV) from human blood and water samples using polypyrrole film and analysis with ion mobility spectrometry

The analysis of incurred material from animals treated with pharmacologically active substances is an efficient way to check the accuracy of a method. Tylosin A was chosen for the preparation of that material because it is highly effective in controlling active infections of American Foulbrood (AFB), a global threat to apiculture, but residues in honey are not allowed according to European legislation. For this reason an in-house reference material of honey containing the macrolide tylosin A and its degradation product desmycosin (tylosin B) was prepared. After the treatment of a beehive with the appropriate macrolide tylosin A, the honey samples were collected. The incurred honey material was diluted by mixing with blank honey. Concentrations of 25.81 μg kg(-1) for tylosin A and of 19.28 μg kg(-1) for its degradation product desmycosin (tylosin B) were reached. The homogeneity was checked by analysing 12 bottles in duplicate. The stability was tested at different defined temperatures and storage conditions. The reference material described above was homogeneous and stable. Samples of this in-house reference material were used for the realisation of a proficiency test with international participation. All participants accomplished satisfying results with the exception of one laboratory.