North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Ruthenium. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Asymmetric Henry reaction catalysed by L-proline derivatives in the presence of Cu(OAc)2: isolation and characterization of an in situ formed Cu(II) complex

Abstract: Synthesis of asymmetric β-nitroalcohols by the Henry reaction is one of the most exploited carbon–carbon bond-forming reactions owing to the versatility of both functional groups for synthetic manipulation by functional group interconversion. Here we report synthesis of a series of proline-derived compounds to study their catalytic activities for asymmetric Henry reaction in the presence of Cu(OAc)2.H2O. The proline derivative, 2-((E)-(((S)-1-benzylpyrrolidinyl)diphenylmethylimino)methyl)phenol 1 showed optimum catalytic activity. The catalytic species Cu(II)–1 complex, formed in situ, was isolated and characterized by various spectroscopic techniques and X-ray crystallography to show a cis-N2O2 coordination geometry. Asymmetric β-nitroalcohols were achieved without the use of added base, unlike most of the reported protocols. Copyright © 2014 John Wiley & Sons, Ltd.

Exact expressions for minor hysteresis loops in the random field Ising model on a Bethe lattice at zero temperature.

Abstract: We obtain exact expressions for the minor hysteresis loops in the ferromagnetic random field Ising model on a Bethe lattice at zero temperature in the case when the driving field is cycled infinitely slowly.

Expression of ornithine-urea cycle enzymes in early life stages of air-breathing walking catfish Clarias batrachus and induction of ureogenesis under hyper-ammonia stress.

Abstract: The air-breathing walking catfish Clarias batrachus is a potential ureogenic teleost with having a full complement of ornithine–urea cycle (OUC) enzymes expressed in various tissues. The present study was aimed at determining the pattern of nitrogenous waste excretion in the form of ammonia-N and urea-N along with the changes of tissue ammonia and urea levels, and the expression of OUC enzymes and glutamine synthetase (GSase) in early life stages of this teleost, and further, to study the possible induction of ureogenesis in 15-day old fry under hyper-ammonia stress. The ammonia and urea excretion was visible within 12 h post-fertilization (hpf), which increased several-fold until the yolk was completely absorbed by the embryo. Although all the early developing stages were primarily ammoniotelic, they also excreted significant amount of nitrogen (N) in the form of urea-N (about 35–40% of total N). Tissue levels of ammonia and urea also increased along with subsequent developmental stages at least until the yolk absorption stage. All the OUC enzymes and GSase were expressed within 4–12 hpf showing an increasing trend of activity for all the enzymes until 350 hpf. There was a significant increase of activity of GSase, carbamyl phosphate synthetase III (CPSase III) and argininosuccinate lyase enzymes (ASL), accompanied with significant increase of enzyme protein concentration of at least two enzymes (GSase and CPSase III) in the 15-day old fry following exposure to 10 mM NH4Cl as compared to respective controls kept in water over a period of 72 h. Thus, it appears that the OUC enzymes are expressed in early life stages of walking catfish like other teleosts, but at relatively high levels and remain expressed all through the life stages with a potential of stimulation of ureogenesis throughout the life cycle as a sort of physiological adaptation to survive and breed successfully under hyper-ammonia and various other environmental-related stresses.

Structure and function of a sub-tropical humid forest of Meghalaya I. Vegetation, biomass and its nutrients

Abstract: The peripheral disturbed zone of a 50-year old stand of the forest at Lailad was dominated byDendrocalamus hamiltonii, an early successional bamboo characteristic of a secondary successional fallow of not more than 20–25 years while the central undisturbed zone hadSchima wallichii, Castanopsis indica andShorea robusta as important components. The biomass of the forest was computed as 137×108 kg/ha of which 64.7% was in the central zone. The contribution by different species both in the central and peripheral zone of the forest was worked out. Linear relationship betweendbh/d 2 h and biomass was worked out for different species. The standing crop had: N, 953; P, 284; K, 600; Ca, 2281; and Mg, 450 kg/ha, of which 60% was in the central zone of the forest.

Biotechnological enhancement of capsaicin biosynthesis in cell suspension cultures of Naga King Chili ( Capsicum chinense Jacq.)

Abstract: Cell suspension cultures were initiated from hypocotyl derived callus to induce capsaicin biosynthesis in suspension cultures of Naga King Chili (Capsicum chinense Jacq.). Efficient capsaicin production with high growth index (GI) was obtained by exposing cells to salicylic acid (SA) and calcium channel modulators in suspension cultures. The time course of capsaicin formation is related to the cell growth profile in a batch culture. Cells cultivated in the standard medium (SM) initially showed low level of capsaicin yield during active growth. When the cells approached stationary phase, cell growth and cell viability decreased whereas capsaicin production increased continuously. In the fed-batch cultures, the highest capsaicin yield (567.4 ± 8.1 μgg(1) fresh weight) (f.wt) was obtained by feeding the cells with 1 mM SA. However, SA feeding during cultivation repressed the cell growth. Enhanced cell growth (3.1 ± 0.1 GI/culture) and capsaicin yield (534 ± 7.8 μgg(-1)f.wt) were obtained when the cells were fed with calcium ionophore A23187 (0.5 mM) on day 25 as compared to the control. Addition of the calcium channel blocker verapamil hydrochloride (100 mM) inhibited cell growth and capsaicin production in Naga King Chili suspension cell cultures.