Glycol-based sol-gel process for the fabrication of ferroelectric PZT thin films

A new sol-gel system using ethylene glycol was developed for the fabrication of PZT thin films with compositions near the morphotropic phase boundary Pb(Zr_0.52Ti_0.48)O₃. Ethylene glycol was used as both a chelating agent and a solvent to replace the highly toxic methoxyethanol used in previous formulations. Thin films were deposited by spin coating the solutions onto platinized silicon substrates. Films were completely crystallized by about 600°C and contained the ferroelectric perovskite phase. A dielectric constant of about 750–800 at 1 KHz was obtained for thin films of 0.3 µm thickness. The hysteresis measurements revealed a remanent polarization of 15 mC/cm² with a coercive field of 60 kV/cm.     

Role of axial ligand on the electronic structures of active intermediates in cytochrome P-450, peroxidase and catalase

DFT method (B3LYP) with 6-31G^* basis set was utilized in the computation of a fully optimized structure, net atomic charges and spin densities of the intermediate of cytochrome P-450-oxoiron(IV) porphyrin cation radical, compound I – in the presence of axial ligand such as thiolate (SMe⁻) imidazole (IM), phenoxide (OPh⁻), methoxide (OMe⁻) and chloride (Cl⁻). The results show doublet states in compound I are about 2–4 kcal/mol more stable than quartet states for all aforementioned ligands, and the doublet state is the ground state in all cases. However, electron donor ability of the ligands are in the order of SMe⁻ > IM > OMe⁻ > OPh⁻ > Cl⁻. Also the active oxidant intermediate of cytochrome P-450 between different mesomeric structures select sulfur oxygen radical type structure and can be viewed as (RS^↓)Fe^↑(IV)(O^↑)(Por). In horseraddish peroxidase (HRP) and peroxidase with histidine axial ligand π cation radical character of porphyrin ring is preferred (Im)Fe^↑(IV)(O^↑)(Por^↓). For the ligands such as OMe⁻, OPh⁻ and Cl⁻ oxidation mainly took place on the iron and the active intermediate can be viewed as (L)Fe^↑(V)(O)(Por) with one unpaired electron localized on the iron.     

Chemical composition and antimicrobial activity of the essential oils of Ferula latisecta and Mozaffariania insignis from Iran

The hydrodistilled oils from the aerial parts of Ferula latisecta and Mozaffariania insignis, which is endemic to Iran, were analyzed by GC and GC/MS. (Z)-Ocimenone (32.4%), (E)-ocimenone (20.3%), and cis-pinocarvone (11.4%) were the main components among the 22 constituents characterized in the oil of F. latisecta, representing 87.7% of the total components detected. Twenty-five compounds were identified in the oil of M. insignis, representing 99.0% of the total oil, with octyl acetate (41.1%), β-pinene (30.3%), and α-pinene (23.9%) as the main constituents. The essential oils were examined for their potential antimicrobial activities. Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 561–563, November–December, 2006.     

Study of size, type and the kerma approximation for thermoluminescent dosimetry

This study aimed to investigate effects of the thermoluminescent dosimeter (TLD) size and type on the absorbed dose value by using of Monte Carlo calculations. The options in creating conditions to establish the kerma approximation were also studied. The Monte Carlo N-Particle (MCNPX 2.4.0) transport code was used to design simulations. Results of this work indicate that if common mineral materials of TLDs are replaced by air and a huge volume is applied for the TLD, the accurate assessment of absorbed doses is possible while the photon energy fluence in the TLD cell is convoluted with mass energy absorption coefficients of the real TLD material. In this method the simulation run-time is strongly decreased.     

In Silico and Experimental Characterization of Chimeric Bacillus thermocatenulatus Lipase with the Complete Conserved Pentapeptide of Candida rugosa Lipase

Lipases are one of the highest value commercial enzymes as they have broad applications in detergent, food, pharmaceutical, and dairy industries. To provide chimeric Bacillus thermocatenulatus lipase (BTL2), the completely conserved pentapeptide (¹¹²Ala-His-Ser-Gln-Gly¹¹⁶) was replaced with similar sequences (²⁰⁷Gly-Glu-Ser-Ala-Gly²¹¹) of Candida rugosa lipase (CLR) at the nucleophilic elbow region. For this purpose, three mutations including A112G, H113E, and Q115A were inserted in the conserved pentapeptide sequence of btl2 gene. Based on the crystal structures of 2W22, the best structure of opened form of the chimeric lipases were garnered using the MODELLER v9.10 software. The native and chimeric lipases were docked to a set of ligands, and a trial version of Molegro Virtual Docker (MVD) software was used to obtain the energy values. Docking results confirmed chimeric lipase to be better than the native lipase. Following the in silico study, cloning experiments were conducted and expression of native and chimeric btl2 gene in Pichia pastoris was performed. The native and chimeric lipases were purified, and the effect of these mutations on characteristics of chimeric lipase studied and then compared with those of native lipase. Chimeric lipase exhibited 1.6-fold higher activity than the native lipase at 55 °C. The highest percentage of both lipases activity was observed at 60 °C and pH of 8.0. The ion Ca²⁺ slightly inhibited the activity of both lipases, whereas the organic solvent enhanced the lipase stability of chimeric lipase as compared with the native lipase. According to the results, the presence of two glycine residues at the conserved pentapeptide region of this chimeric lipase (¹¹² Gly-Glu-Ser-Ala-Gly ¹¹⁶) may increase the flexibility of the nucleophilic elbow region and affect the enzyme activity level.     

Highly functionalized pyrazolines from symmetric and asymmetric 1,2-disulfonylhydrazines: a combination of experimental and DFT perspectives

Chemistry of Heterocyclic Compounds - In this work, new pyrazole derivatives were prepared by one-pot three-component reaction emloying symmetric and asymmetric 1,2-disulfonyl-hydrazines,...     

Effect of substituents and encapsulation on the catalytic activity of copper(II) complexes of two tridentate Schiff base ligands based on thiophene: benzyl alcohol and phenol oxidation reactions

Encapsulation of Cu(II) complexes of methyl-2-(2-hydroxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]-thiophene-3-carboxylate (HL¹) and 2-ethyl-4-methyl 5-(2-hydroxybenzylideneamino)-3-methylthiophene-2,4-dicarboxylate (HL²) in the supercages of zeolite NaY was performed by the flexible ligand method. The neat and encapsulated complexes were characterized by physicochemical and spectroscopic methods and employed as catalysts for oxidation of benzyl alcohol and phenol. The encapsulated complexes were both more reactive and stable as catalysts than the corresponding free complexes. The encapsulated complexes could be reused several times. Complexes of HL² were more reactive than those of HL¹, probably due to the electron-withdrawing effect of the CO₂Et group.     

Starch nanoparticles as a bio-nanocatalyst in synthesis of diheteroaryl thioethers

Nanostarch is shown to be a highly efficient, eco-friendly and heterogenous organocatalyst for the synthesis of the diheteroaryl thioethers via one-pot reaction of methylcarbonyls, thiourea and iodine in DMSO. This method offers significant advantages such as available starting materials, higher purity and excellent yield of products, very easy reaction conditions and absence of any tedious purification. Furthermore, because of employing eco-friendly catalyst without using transition metal catalysts, this novel method emerges as a green-approach leading to less harmful residues. Moreover, a mechanism was proposed to rationalize the reaction and the role of starch nanoparticles was also investigated in these transformations.     

Synthesis,biological evaluation and molecular docking study of dihydropyrimidine derivatives as potential anticancer agents

A series of dihydropyrimidine analogues were prepared via one-pot Biginelli three-component condensation reaction and characterized by NMR, FT-IR, MS spectra, and element analysis. Subsequently, they were screened for in vitro anticancer effect. These analogues revealed good cytotoxic activity against three human cancer cell lines including MCF-7, HepG-2, and A549. Among these analogues, compounds 4d and 4h were the most potent against three cell lines. Cell viability assays indicated 4a and 4c had lower cytotoxicity. In vitro cytotoxicity study on all synthesized compounds demonstrated that introduction of electron withdrawing substituents on C4 position of phenyl ring of dihydropyrimidine contributed to the antiproliferative potency. Moreover, in silico molecular docking results stipulated a sign of good correlation between experimental activity and calculated binding affinity. It proved 4d and 4h as the strongest compounds. Binding modes of analogues proposed the involvement of hydrophobic interactions and hydrogen bonds with Eg5 active site. Structure activity relationship studies indicated that incorporating electron withdrawing substituents on C4 position of phenyl ring of dihydropyrimidine are important for this biological activity.