Dielectrical Properties of CeO2 Nanoparticles at Different Temperatures

A template-free precipitation method was used as a simple and low cost method for preparation of CeO₂ nanoparticles. The structure and morphology of the prepared nanoparticle samples were studied in detail using X-ray diffraction, Raman spectroscopy and Scanning Electron Microscopy (SEM) measurements. The whole powder pattern modelling (WPPM) method was applied on XRD data to accurately measure the crystalline domain size and their size distribution. The average crystalline domain diameter was found to be 5.2 nm, with a very narrow size distribution. UV-visible absorbance spectrum was used to calculate the optical energy band gap of the prepared CeO₂ nanoparticles. The FT-IR spectrum of prepared CeO₂ nanoparticles showed absorption bands at 400 cm^-1 to 450 cm^-1 regime, which correspond to CeO₂ stretching vibration. The dielectric constant (ε_r) and dielectric loss (tan δ) values of sintered CeO₂ compact consolidated from prepared nanoparticles were measured at different temperatures in the range from 298 K (room temperature) to 623 K, and at different frequencies from 1 kHz to 1 MHz.     

Purification to homogeneity and properties of mannosidase II from mung bean seedlings

Mannosidase II was purified from mung bean seedlings to apparent homogeneity by using a combination of techniques including DEAE-cellulose and hydroxyapatite chromatography, gel filtration, lectin affinity chromatography, and preparative gel electrophoresis. The release of radioactive mannose from GlcNAc[3H]Man5GlcNAc was linear with time and protein concentration with the purified protein, did not show any metal ion requirement, and had a pH optimum of 6.0. The purified enzyme showed a single band on SDS gels that migrated with the Mr 125K standard. The enzyme was very active on GlcNAcMan5GlcNAc but had no activity toward Man5GlcNAc, Man9GlcNAc, Glc3Man9GlcNAc, or other high-mannose oligosaccharides. It did show slight activity toward Man3GlcNAc. The first product of the reaction of enzyme with GlcNAcMan5GlcNAc, i.e., GlcNAcMan4GlcNAc, was isolated by gel filtration and subjected to digestion with endoglucosaminidase H to determine which mannose residue had been removed. This GlcNAcMan4GlcNAc was about 60% susceptible to Endo H indicating that the mannosidase II preferred to remove the alpha 1,6-linked mannose first, but 40% of the time removed the alpha 1,3-linked mannose first. The final product of the reaction, GlcNAcMan3GlcNAc, was characterized by gel filtration and various enzymatic digestions. Mannosidase II was very strongly inhibited by swainsonine and less strongly by 1,4-dideoxy-1,4-imino-D-mannitol. It was not inhibited by deoxymannojirimycin.     

Promotion of Growth in Mungbean (Phaseolus aureus Roxb.) by Selenium is Associated with Stimulation of Carbohydrate Metabolism

The mungbean plants were grown hydroponically in the absence (control) or presence of 0.1, 0.25, 0.50 and 0.75 ppm selenium (as sodium selenate) for 10 days. The growth of shoots and roots increased with application of selenium with greater extent in shoots. With 0.5 and 0.75 ppm Se levels, the shoot growth was stimulated by 24% to 27% over control, respectively, while the roots showed a corresponding increase of 18-19%, respectively. The shoot-to-root ratio was enhanced significantly with Se application and maximum effects occurred at 0.75 ppm Se. A significant increase was observed in chlorophyll and cellular respiration ability with 0.5 and 0.75 ppm selenium. The increase in growth by selenium was accompanied by elevation of starch, sucrose and reducing sugars. The activity of starch hydrolysing enzymes--amylases and sucrose hydrolysing enzyme--invertase was stimulated significantly with selenium. This was associated with elevation of activities of sucrose synthesising enzymes--sucrose synthase and sucrose phosphate synthase. It was concluded that increase in growth of shoots and roots by application of Se was possibly the result of up-regulation of enzymes of carbohydrate metabolism thus providing energy substrates for enhanced growth.     

In vitro regeneration of Trifolium glomeratum

In vitro regeneration of Trifolium glomeratum, a leguminous forage species, was attempted through leaf, petiole, cotyledon, hypocotyl, collar and root explants and two media combinations. Root and collar explants showed no callus induction. Medium with 0.05 mg dm⁻³ α-naphthaleneacetic acid (NAA) and 0.10 mg dm⁻³ N⁶-benzyladenine (BA) was more effective for hypocotyl explant whereas cotyledon and petiole explant were more responsive to 5.0 mg dm⁻³ NAA and 1.0 mg dm⁻³ BA. Friable, green calli obtained from petiole explant on this medium showed organogenetic potential. Modified root-inducing medium having 0.21 mg dm⁻³ indole-3-acetic acid and 2.5 % sucrose was successful for root induction and plantlets were successfully transferred to field after hardening and Rhizobium inoculation.     

Purification and characterization of dolichyl-P-mannose:Man5(GlcNAc)2-PP-dolichol mannosyltransferase

The dolichyl-P-mannose:dolichyl-PP-heptasaccharide alpha-mannosyltransferase (2.4.1.130), which catalyzes the transfer of mannose from dolichyl-P-mannose to the Man5(GlcNAc)2-PP-dolichol acceptor glycolipid, was solubilized from pig aorta microsomes with 0.5% NP-40 and purified 985-fold by a variety of conventional methods. The partially purified enzyme had a pH optimum of 6.5 and required Ca2+, at an optimum concentration of 8-10 mM, for activity. Mn2+ was only 20% as effective as Ca2+, and Mg2+ was inhibitory. The mannosyltransferase activity was also inhibited by the addition of EDTA to the enzyme, but this inhibition was fully reversible by the addition of Ca2+. The enzyme was quite specific for dolichyl-P-mannose as the mannosyl donor and Man5(GlcNAc)2-PP-dolichol as the mannosyl acceptor. The Km values for dolichyl-P-mannose and the acceptor lipid Man5(GlcNAc)2-PP-dolichol were 1.8 and 1.6 microM. On Bio-Gel P-4 columns and by HPLC, the radiolabeled oligosaccharide formed during incubation of dolichyl-P-[14C]mannose and unlabeled Man5(GlcNAc)2-PP-dolichol with the purified enzyme behaved like Man6(GlcNAc)2. This octasaccharide was susceptible to digestion by endoglucosaminidase H, indicating that the newly added mannose was attached to the 6-linked mannose in an alpha 1,3-linkage. This linkage was further confirmed by acetolysis of the oligosaccharide product [i.e., Man6(GlcNAc)2], which gave a labeled disaccharide as the major product (greater than 90%).     

An insight into medicinal chemistry of anticancer quinoxalines

Quinoxalines are benzopyrazines containing benzene and pyrazine rings fused together. In the recent past, quinoxalines have attracted Medicinal Chemists considerably for their syntheses and chemistry due to their distinct pharmacological activities. Diverse synthetic protocols have been developed via multicomponent reactions, single pot synthesis and combinatorial approach using efficient catalysts, reagents, and nano-composites etc. Further, the versatility of the quinoxaline core and its reasonable chemical simplicity devise it extremely promising source of bioactive compounds. Therefore, a wide variety of bioactive quinoxalines has been realised as antitumour, antifungal, anti-inflammatory, antimicrobial, and antiviral agents. Already, a few of them are clinical drugs while many more are under various phases of clinical trials. Present review focuses on chemistry and pharmacology (both efficacy and safety) of quinoxalines and also provides some insight in to their structure–activity relationship.     

Transgene delivery using poly(amino ether)-gold nanorod assemblies

Gold nanorods (GNRs) have emerged as promising nanomaterials for biosensing, imaging, photothermal treatment, and therapeutic delivery for several diseases, including cancer. We have generated poly(amino ether)-functionalized gold nanorods (PAE-GNRs) using a layer-by-layer deposition approach; polymers from a poly(amino ether) library recently synthesized in our laboratory were employed to generate the PAE-GNR assemblies. PAE-GNR assemblies demonstrate long-term colloidal stability as well as the capacity to bind plasmid DNA by means of electrostatic interactions. Sub-toxic concentrations of PAE-GNRs were employed to deliver plasmid DNA to prostate cancer cells in vitro. PAE-GNRs generated using 1,4C-1,4Bis, a cationic polymer from our laboratory demonstrated significantly higher transgene expression and exhibited lower cytotoxicities when compared to similar assemblies generated using 25 kDa poly(ethylene imine) (PEI25k-GNRs), a current standard for polymer-mediated gene delivery. The roles of polyelectrolyte chemistry and zeta-potential in determining transgene expression efficacies of PAE-GNR assemblies were investigated. Our results indicate that stable and effective PAE-GNR assemblies are a promising engineered platform for transgene delivery. PAE-GNRs also have the potential to be used simultaneously for photothermal ablation, photothermally enhanced drug and gene delivery, and biological imaging, thus making them a powerful theranostic platform.