Dynamic and rheological properties of soft biological cell suspensions

Quantifying dynamic and rheological properties of suspensions of soft biological particles such as vesicles, capsules, and red blood cells (RBCs) is fundamentally important in computational biology and biomedical engineering. In this review, recent studies on dynamic and rheological behavior of soft biological cell suspensions by computer simulations are presented, considering both unbounded and confined shear flow. Furthermore, the hemodynamic and hemorheological characteristics of RBCs in diseases such as malaria and sickle cell anemia are highlighted.     

The effect of porosity on the laser induced damage threshold of TiO2 and ZrO2 single layer films

Monolayer ZrO₂ and TiO₂ films were prepared on BK7 glass by physical vapor deposition (PVD) and were subsequently annealed for 1 h at 300 °C. By using the transmission spectra of two samples and the envelope method, the refractive index dispersion and extinction coefficients have been calculated. Laser induced damage threshold (LIDT) measurement shows that despite slight differences between the extinction coefficients of the two samples, the LIDT parameter of the ZrO₂ film is greater than that of the TiO₂ film. This fact leads us to consider thermal conductivity as an important parameter for interpreting the LIDT difference. According to our theoretical analysis, as a consequence of increase in the number of thermal barriers along poorer film, its thermal conductivity, and hence LIDT, decreased, which is in agreement with our experimental results. The measured porosity of the two samples shows higher porosity for TiO₂ single layer, which is in agreement with atomic force (AFM) images. The gradual and smooth damage morphology of ZrO₂ observed in optical images implies higher thermal conductivity than TiO₂.     

Silphox [POCl3−n (SiO2) n ] as a New,Efficient, and Heterogeneous Reagent for the Synthesis of Benzimidazole Derivatives Under Microwave Irradiation

Silphox [POCl_3-n(SiO₂)_n] efficiently catalyzes the condensation of benzene-1,2-diamine with mono and dicarboxylic acids under microwave irradiation to afford benzimidazole derivatives in high yields and short reaction times.     

KF/Al2O3 as an Efficient,Green, and Reusable Catalytic System for the Solvent-Free Synthesis of N-Alkyl Derivatives of Sulfonamides via Michael Reactions

KF/Al ₂ O ₃ efficiently catalyzes the microwave-assisted Michael addition of sulfonamides to α,β-unsaturated esters under solvent-free conditions to afford N-alkyl derivatives of sulfonamides as biologically interesting compounds in high yields and in short reaction times. In this reaction, N,N-dialkylsulfonamides are also produced, but in very low yields.     

Novel Preparation of Polyethylene from Nano‐extrusion Polymerization Inside the Nanochannels of MCM‐41/MgCl2/TiCl4 Catalysts

The MCM‐41 and SiO₂ supported TiCl₄ and TiCl₄/MgCl₂ catalysts with different molar ratios of Mg/Ti were synthesized and used for ethylene polymerization under atmospheric pressure. The nanochannels of MCM‐41 serve as nanoscale polymerization reactor and the polyethylene nanofibers were extruded during the reaction. The nanofibers were observed in SEM micrographs of resulting polyethylene. The effect of MgCl₂ on catalytic activity and thermal properties of resulting polyethylene is investigated too. In the presence of MgCl₂, the catalytic activity increased and more crystalline polyethylene with higher melting points were formed. However, no fibers could be observed in the polyethylene prepared by SiO₂ supported catalysts.     

Synthesis and molecular modeling study of Cu(Ⅱ) complexes derived from 2-(diphenylmethylene)hydrazinecarbothioamide derivatives with cholinesterase inhibitory activities

Thiosemicarbazones of 2-amino-5-chlorobenzophenone and 3-aminobenzophenone（L¹-L⁴） have been synthesized and their Cu（Ⅱ） complexes（1-4） were afforded via coordination with cupric chloride.All these compounds were characterized by UV-vis and IR spectroscopy together with CHN elemental analysis.NMR spectroscopy was also applied to characterize the ligands.In vitro chohnesterase inhibitory assays for the complexes（1-4） showed IC₅₀ values less than 10μmol/L,with complex 1 exhibiting the most activity,IC₅₀=2.15μmol/L and 2.16μmol/L for AChE and BuChE,respectively. Molecular modeling simulation revealed the binding interaction template for complex 1 with the AChE and BuChE receptors.In DPPH assay,the complexes also showed more in vitro antioxidant activities in comparison to their parent ligands.     

Theoretical studies on tautomerism of imidazole-2-selenone

The tautomerism of all possible forms of imidazole selenone (ISe1–ISe6), induced by proton transfer was studied theoretically in different environments including gas phase, continuum solvent, and microhydrated environment with one explicit water molecule. The calculations were performed at the MP2 and CAM-B3LYP levels of theory, separately. It was found that the imidazole selenone, in the form of ISe3, is the most stable isomer in both gas phase and solvent. The activation energy for conversion of ISe3 to imidazole selenol (ISe6), as the second stable form, is 41.72 and 43.0 kcal/mol in the gas phase and water, respectively. The infrared spectral frequencies as well as the vibrational frequency shifts were reported and assigned to their corresponding vibrational modes. In addition, the variation of dipole moments and charges on the atoms with change of solvent was studied. The energies of HOMO, LUMO, and HOMO–LUMO gap were calculated in both gas phase and solvent. Specific solvent effects with addition of water molecule near the electrophilic centers of tautomers and the transition states of proton transfer, assisted by water molecule, were investigated. It was found that the water molecule can form different hydrogen bonds with the molecule. Aggregation of the isomers with water molecule does not change the order of stability of isomers, but proton transfer reaction assisted by a water molecule needs less energy than when the proton shifts through the intramolecular process.     

Electroanalysis of single-nucleotide polymorphism by hairpin DNA architectures

Genetic analysis of infectious and genetic diseases and cancer diagnostics require the development of efficient tools for fast and reliable analysis of single-nucleotide polymorphism (SNP) in targeted DNA and RNA sequences often responsible for signalling disease onset. Here, we highlight the main trends in the development of electrochemical genosensors for sensitive and selective detection of SNP that are based on hairpin DNA architectures exhibiting better SNP recognition properties compared with linear DNA probes. SNP detection by electrochemical hairpin DNA beacons is discussed, and comparative analysis of the existing SNP sensing strategies based on enzymatic and nanoparticle signal amplification schemes is presented.     

Effect of silver nanoparticles concentration on the metal enhancement and quenching of ciprofloxacin fluorescence intensity

Concentration effect of silver nanoparticles (AgNPs) on the photophysical properties of ciprofloxacin (Cip) have been investigated using optical absorption and fluorescence techniques. When performed AgNPs solution was added to the Cip solution, metal-enhanced fluorescence intensity and a blue-shift of 20 nm in the maximum emission spectra of Cip has been observed. The enhanced intensity of this system is strongly dependent on the AgNPs concentration and largest at the 6.0 × 10^?6 mol L^?1. With increase of AgNPs concentration, quenching of fluorescence is observed. Stern–Volmer quenching constants have been calculated at four temperatures. The results show the quenching constants are directly correlated with temperature. It indicates the quenching mechanism is the dynamic quenching in nature rather than static quenching. From which we determined the activation energy for the quenching of Cip-AgNPs to be about 31.1 kJ mol^?1. In addition, in the presence of optimum AgNPs concentration, a sensitive fluorimetric method for the determination of ciprofloxacin at the range 5.0 × 10^?7–3.0 × 10^?5 mol L^?1 and the detection limit of 2 × 10^?8 mol L^?1 in solution is proposed.     

New 5-bromo-2-hydroxybenzaldehyde S-ethylisothiosemicarbazone and its mixed-ligand Cu(II) complex with imidazole: synthesis, characterization and DFT calculation

A new Schiff base ligand of 5-bromo-2-hydroxybenzaldehyde S-ethyl-isothiosemicarbazone (H₂L) was synthesized and its mixed-ligand Cu(II) complex was also prepared by reaction of Cu(NO₃)₂·3H₂O with H₂L and imidazole. Their structures were fully characterized by elemental analysis, FT-IR, molar conductivity and UV-Vis methods. The analytical data suggest that the metal, H₂L and imidazole ratios in the Schiff base complex are 1:1:1. Single crystal diffraction was also used to better understand the molecular structure of the Cu(II) complex. The results of physico-chemical analyses of the Schiff base complex reveal the coordination geometry around the central atom is square planar. The H₂L ligand (NNO donor) is coordinated to the metal center as a tridentate bionegatively agent. Another position of the square planar geometry is occupied by the imidazole ligand. Furthermore, computational studies of the new complex were performed by carrying out DFT calculations. Geometry optimization and natural band analysis of the complex is discussed in further detail.