Ultrasonic assisted Fischer glycosylation: generating diversity for glycochemistry

In this study ultrasound has been utilised for the Fischer glycosylation using free sugars and sulphuric acid immobilized on silica as catalyst. N-acetyl-d-glucosamine, N-acetyl-d-galactosamine, d-glucose, d-galactose, d-mannose, l-fucose, and lactose were glycosylated with propargyl alcohol or 2-azidoethanol affording the corresponding glycosides, with the production of the α-glycopyranoside as the dominant product. Remarkable acceleration of the glycosylation reactions (15 min–2 h compared to several hours) over reported procedures together with good yields were always observed.     

Acetylcholinesterase Immobilization on Polyacrylamide/Functionalized Multi-walled Carbon Nanotube Nanocomposite Nanofibrous Membrane

In this work, polyacrylamide/multi-walled carbon nanotubes (MWCNT) solution is electrospun to nanocomposite nanofibrous membranes for acetylcholinesterase enzyme immobilization. A new method for enzyme immobilization is proposed, and the results of analysis show successful covalent bonding of enzymes on electrospun membrane surface besides their non-covalent entrapment. Fourier transform infrared spectroscopy, mechanical and thermal investigations of nanofibrous membrane approve successful cross-linking and enzyme immobilization. The enzyme relative activity and kinetic on both pure and nanocomposite membranes is investigated, and the results show proper performance of designed membrane to even improve the enzyme activity followed by immobilization compared to free enzyme. Scanning electron microscopy images show nanofibrous web of 3D structure with a low shrinkage and hydrogel structure followed by enzyme immobilization and cross-linking. Moreover, the important role of functionalized carbon nanotubes on final nanofibrous membrane functionality as a media for enzyme immobilization is investigated. The results show that MWCNT could act effectively for enzyme immobilization improvement via both physical (enhanced fibers’ morphology and conductivity) and chemical (enzyme entrapment) methods.

Analysis of rat testicular proteome following 30‐day exposure to 900 MHz electromagnetic field radiation

The use of electromagnetic field (EMF) generating apparatuses such as cell phones is increasing, and has caused an interest in the investigations of its effects on human health. We analyzed proteome in preparations from the whole testis in adult male Sprague‐Dawley rats that were exposed to 900 MHz EMF radiation for 1, 2, or 4 h/day for 30 consecutive days, simulating a range of possible human cell phone use. Subjects were sacrificed immediately after the end of the experiment and testes fractions were solubilized and separated via high‐resolution 2D electrophoresis, and gel patterns were scanned, digitized, and processed. Thirteen proteins, which were found only in sham or in exposure groups, were identified by MALDI‐TOF/TOF‐MS. Among them, heat shock proteins, superoxide dismutase, peroxiredoxin‐1, and other proteins related to misfolding of proteins and/or stress were identified. These results demonstrate significant effects of radio frequency modulated EMFs exposure on proteome, particularly in protein species in the rodent testis, and suggest that a 30‐day exposure to EMF radiation induces nonthermal stress in testicular tissue. The functional implication of the identified proteins was discussed.     

A mild and highly efficient method for the synthesis of 5‐aryl‐(N‐phenyl‐)6H‐1,3,4‐thiadiazin‐2‐aminium salts using reusable heterogeneous catalysts

5‐Aryl‐6H‐1,3,4‐thiadiazin‐2‐aminium and 5‐aryl‐N‐phenyl‐6H‐1,3,4‐thiadiazin‐2‐aminium salts have efficiently been synthesized from the reaction of thiosemicarbazide and α‐haloketones in acetonitrile at room temperature using i) silica supported sodium hydrogen sulfate and ii) silica sulfuric acid as reusable heterogeneous catalysts. The experimental procedure is simple and the products are obtained in high yields.     

External magnetic field-dependent tricritical points of uniaxial-to-biaxial nematic transition

External magnetic field-dependent behavior of tricritical points of uniaxial–biaxial nematic phase transition in a mixture of prolate and oblate molecules has been studied using the Landau phenomenological theory. Topological classification of phase diagrams in the field-temperature coordinates is performed using a sixth-order term in order parameter tensor. For both prolate and oblate molecules, the tricritical order parameters corresponding to the uniaxial–biaxial increase with the intensity of the external magnetic field. Field-induced paranematic phase has only been reported for prolate molecules, but for oblate molecules, field-induced splitting of the order parameter has been reported.     

Silica supported ammonium dihydrogen phosphate (NH4H2PO4/SiO2):A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes

Silica supported ammonium dihydrogen phosphate (NH₄H₂PO₄/SiO₂) is found to be a recyclable heterogeneous catalyst for a rapid and efficient synthesis of various aryl-14-H-dibenzo[a,j]xanthenes with excellent yields under solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times and milder conditions.     

A novel broadband dispersion compensating square-lattice photonic crystal fiber

In this paper we propose a novel square-lattice photonic crystal fiber (SPCF) for dispersion compensation in a wide range of wavelengths. Perfectly matched layer (PML) is considered for the boundary treatment and an efficient compact two dimensional finite-difference frequency-domain (2-D FDFD) method is employed to model square-lattice photonic crystal fibers (SPCF). It has been shown with selecting appropriate parameters for SPCF it is possible to obtain high negative dispersion coefficient, negative dispersion slope over E to L wavelengths, confinement losses less than 10^?5?dB/m and splice losses less than 3.6 dB. The designed SPCF exhibits a relative dispersion slope (RDS) of 3.543 × 10^?3 nm^?1 which is closely matched to the RDS of conventional single mode fibers.