Embedding theorems on hyperelliptic varieties

In this paper, we investigate linear systems on hyperelliptic varieties. We prove analogues of well-known theorems on abelian varieties, like Lefschetz’s embedding theorem and higher k-jet embedding theorems. Syzygy or \(N_p\) -properties are also deduced for appropriate powers of ample line bundles. This is a first result on linear series, on hyperelliptic varieties.     

Intriguing Manipulation of Metal‐Enhanced Fluorescence for the Detection of CuII and Cysteine

Commercially available salicylaldehyde, in alkaline medium, exhibits strong fluorescence after one hour of UV exposure in the presence of Ag^I. The phenolic group of salicylaldehyde is converted into the quinone form under alkaline conditions in the presence of AgNO₃, resulting in aggregated Ag(0), which causes approximately 250 times fluorescence enhancement of the in situ produced quinone. Such high silver‐enhanced‐fluorescence (SEF) is selectively quenched by cysteine, arginine, histidine, methionine, and tryptophan. In contrast to the other amino acids, ageing brings selectivity of the cysteine‐induced quenching effect. Interestingly, Cu^II is found to be the only metal ion that exclusively regenerates the lost fluorescence. Thus, quenching and recovery of fluorescence (Turn Off/On) can be used for the selective and sensitive detection of cysteine as well as Cu^II ions in one pot. Alteration of the electric field density around the fluorophore (lightening rod effect) and scattering/absorption cross‐section have been proposed to account for the Off/On fluorescence.     

Influence of correlation and temperature on the electronic structure of bulk and thin film GdN

The influence of correlation and temperature on the electronic structure of bulk and thin film GdN has been studied using the s-f model, which combines the one electron band structure with a many body procedure. The tight binding linear muffin tin orbital (TB-LMTO) method was used to obtain the one electron band structure of the system. The s-f exchange coupling constants for each band were obtained from the spin polarized band structure of the system using a mean field model. Correlation effects are found to be present in the system. However they are not sufficiently strong to cause a correlation induced splitting in the spectrum. Some bands of the thin films of GdN exhibit splitting at T=T_c and it is due to the combined effect of correlation and temperature. The conduction bands of both the bulk and the thin films of GdN exhibit a red shift with respect to temperature.     

Effect of pressure on thed-spacings of the quasicrystal Al-18 a/o Fe

We report the high pressure X-ray studies of quasicrystal Al-18 a/o Fe. It is observed that initially thed-spacings decrease monotonically with pressure, but at 57 kbar there is a sudden fall, indicative of a first order phase transition. The compression and the discontinuities are observed to be highly directional.     

Pion and proton production in forward and backward hemisphere in C-emulsion interaction at 4.5 GeV/c per nucleon

The paper presents an in-depth study on the forward and backward multiplicity correlations in case of pions and protons (from the target) based on the experimental data on ¹²C-emulsion interaction at 4.5 GeV/c per nucleon. The cumulative distribution of their emission angles in the backward hemisphere is presented. The asymmetry parameter (A) and the forward-backward ratio (F/B) as a function of the number of heavy particles (n_h) is also shown. The results reveal many interesting characteristics regarding the backward particle production.     

Real-time monitoring of protein complexes reveals their quaternary organization and dynamics

The dynamics of protein complexes are crucial for their function yet are challenging to study. Here, we present a nanoelectrospray (nESI) mass spectrometry (MS) approach capable of simultaneously providing structural and dynamical information for protein complexes. We investigate the properties of two small heat shock proteins (sHSPs) and find that these proteins exist as dodecamers composed of dimeric building blocks. Moreover, we show that these proteins exchange dimers on the timescale of minutes, with the rate of exchange being strongly temperature dependent. Because these proteins are expressed in the same cellular compartment, we anticipate that this dynamical behavior is crucial to their function in vivo. Furthermore, we propose that the approach used here is applicable to a range of nonequilibrium systems and is capable of providing both structural and dynamical information necessary for functional genomics.     

Optimization of lignin recovery from sugarcane bagasse using ionic liquid aided pretreatment

Ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]oAc) was employed for the pretreatment of sugarcane bagasse (SCB) and extraction of lignin, a potentially valuable by-product of the biofuel industry. Response surface methodology based on central composite design was exploited and thereby an empirical model, exhibiting a coefficient of determination, R², of 0.9890, was established to optimize lignin recovery. In particular, a maximum lignin yield, equal to 90.1%, was calculated at the optimal pretreatment conditions, namely time: 120 min, temperature: 140 °C, and ionic liquid to bagasse ratio equal to 20:1 (wt/wt). The presence of guaiacyl and syringyl rings in lignin was confirmed by Fourier transform infrared spectroscopy (FTIR); whereas UV–Vis spectrophotometry showed that both p-coumaric acid and ferulic acid were contained in the lignin. Thermal analysis indicated a maximum decomposition rate of 2%/°C at 265 °C while Gel permeation chromatography analysis revealed that the molecular weight (M_w) of recovered lignin was equal to 1769 g/mol. Comparison of FTIR spectra of pretreated and untreated bagasse showed a negligible presence of lignin in the pretreated samples. Maximum delignification of bagasse after pretreatment was thus ensured. Thermal stability of the ionic liquid towards recyclability was proven by thermogravimetric analysis. The present study established adequate performance of neat and recycled ([EMIM]oAc) with regard to lignin recovery from SCB.     

Design and synthesis of oxaprozin-1,3,4-oxadiazole hybrids as potential anticancer and antibacterial agents

In the present study, we report design, synthesis and screening of new novel 5-substituted-2-mercapto-1,3,4-oxadiazole analogues appended to oxaprozin for their in vitro anticancer and antibacterial activity. The synthesised compounds were characterized using various spectroscopic techniques. Furthermore, the structure of 5b (2-(2-[4,5-diphenyloxazol-2-yl]ethyl)-5-(ethylthio)-1,3,4-oxadiazole) was unequivocally confirmed by X-ray analysis. Among the series 5c (2-(2-[4,5-diphenyloxazol-2-yl]ethyl)-5-(propylthio)-1,3,4-oxadiazole) showed most promising anticancer activity against A549 cancer cell line and all the reported analogues manifested satisfactory safety profiles against human normal cell line HEK293T. The products exhibited good antibacterial activity and among the tested 5j (2-(2-[4,5-diphenyloxazol-2-yl]ethyl)-5-([4-fluorobenzyl]thio)-1,3,4-oxadiazole) exhibited most potent.     

Hyperaromatic stabilization of arenium ions: acid-catalyzed dehydration of 2-substituted 1,2-dihydro-1-naphthols

Rate constants for acid-catalyzed dehydration of cis-2-substituted 1,2-dihydro-naphthols are well correlated by the Taft relationship log k = -0.49 - 8.8σ(I), with minor negative deviations for OH and OMe. By contrast the trans substituents show a poor correlation with σ(I) and in most cases react more slowly than their cis isomers. The behavior is consistent with rate-determining formation of a 2-substituted carbocation (naphthalenium ion) intermediate that for cis reactants possesses a 2-C-H bond suitably oriented for hyperconjugation with the charge center. For the trans isomers the 2-substituent itself is oriented for hyperconjugation in the initially formed conformation of the cation. It is argued that k(cis)/k(trans) rate ratios for substituents (Me, 8.4; Bu(t), 12.7; Ph, 3.8; NH(3)(+), 160; OH, 440) reflect their hyperconjugating ability relative to hydrogen. Faster reactions of trans isomers are observed for substitutents known (RS, N(3)) or suspected (EtSO, EtSO(2)) of stabilizing the cation by a π or σ neighboring group effect. The good Taft correlation is taken to indicate that cis substuents are reacting normally, differentiated only by their inductive effects. The slower reactions of the trans isomers are the judged to be "abnormal". This is confirmed by comparing effects of cis and trans β-OH substituents on the reactivities of dihydro phenols, naphthols, and phenanthrols. Whereas k(H)/k(OH) for cis substituents varies by less than 8-fold and is consistent with the influence of an inductive effect of the OH group (k(H)/k(OH) ≈ 2000), k(H)/k(OH) for the trans substituents varies by 3 orders of magnitude, reflecting the additional influence of the lesser hyperconjugating ability of a C-OH bond compared to a C-H bond. The magnitude and variation of this difference is consistent with C-H hyperconjugation conferring aromatic character on the arenium ions.     

Ruthenium(II)/(III) complexes of 4-hydroxy-pyridine-2,6-dicarboxylic acid with PPh3/AsPh3 as co-ligand: impact of oxidation state and co-ligands on anticancer activity in vitro

With the aim to develop more efficient, less toxic, target specific metal drugs and evaluate their anticancer properties in terms of oxidation state and co-ligand sphere, a sequence of Ru(II), Ru(III) complexes bearing 4-hydroxy-pyridine-2,6-dicarboxylic acid and PPh(3)/AsPh(3) were synthesized and structurally characterized. Biological studies such as DNA binding, antioxidant assays and cytotoxic activity were carried out and their anticancer activities were evaluated. Interactions of the complexes with calf thymus DNA revealed that the triphenylphosphine complexes could bind more strongly than the triphenylarsine complexes. The free radical scavenging ability, assessed by a series of in vitro antioxidant assays involving DPPH radical, hydroxyl radical, nitric oxide radical, superoxide anion radical, hydrogen peroxide and metal chelating assay, showed that the Ru(III) complexes possess excellent radical scavenging properties compared to those of Ru(II). Cytotoxicity studies using three cancer lines viz HeLa, HepG2, HEp-2 and a normal cell line NIH 3T3 showed that Ru(II) complexes exhibited substantial cytotoxic specificity towards cancer cells. Furthermore, the Ru(II) complexes were found to be superior to Ru(III) complexes in inhibiting the growth of cancer cells.