A generalized log-normal distribution and its goodness of fit to censored data

In life testing experiments, the skewed distributions like log-normal, Weibull, gamma and generalized gamma are the most suitable models for recording the failure time measurements. In this paper, a generalized version of log-normal distribution is proposed and its goodness-of-fit for a randomly censored data set representing the remission times of bladder cancer patients has been demonstrated and compared with other lifetime models considered in the literature. The P-P plots of Kaplan-Meier estimator against the survival functions of the considered models are used to show the goodness-of-fit. A simulation study is also performed to estimate the parameters in both the classical and Bayesian setups.     

Microgram detection of nitriles using resin beads

Summary Some nitriles (benzonitrile, acetonitrile, propionitrile, butyronitrile, and cyanoacetic acid) can be detected by means of ion exchange resin beads after hydrolysis with dil. H₂SO₄ to produce ammonium ions. The ammonium ions are retained by the resin and then detected by the indophenol blue color using sodium hypochlorite and phenol. The new method is more sensitive and selective than the existing methods.

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Zusammenfassung Einige Nitrile (Benzo-, Aceto-, Propio-, Butyronitril und Cyanessig-säure) lassen sich mit Hilfe von Austauscherharz-Perlen nach Hydrolyse mit verd. Schwefelsäure zur Freisetzung von Ammoniumionen nachweisen. Diese werden an dem Harz festgehalten und dann durch Bildung von Indophenolblau mit Hilfe von Hypochlorit und Phenol nachgewiesen. Diese Methode ist empfindlicher und selektiver als bisher existierende Verfahren.

     

Characterization of L‐aspartate crystals grown in gel medium

L‐Aspartate [C₄H₇NO₄], also called as 2‐aminobutanedoioic acid, an organic amino acid was crystallized with the aid of sodium metasilicate gel. Diffusion of the supersaturated solutions in porous gel network by solubility reduction method in silica gel was carried out in our laboratory. The crystals were characterized using powder X‐ray diffraction technique. Fourier transform infrared spectroscopy reveals the presence of functional groups in the crystals. Optical absorbance of the crystals was studied by UV – Visible spectroscopy and the thermal properties were studied by thermo gravimetric analysis. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Proton-ligand and metal ligand stability constants ofN-o-chlorophenylbenzohydroxamic acids with manganese(II), nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II)

Summary The thermodynamic proton-ligand and metal ligand stability constants of the newN-o-chlorophenylbenzohydroxamic acids with manganese, nickel, copper, zinc, cadmium and mercury have been determined in 1 : 1 dioxan : water at 25°.The stability of the complexes mostly follow the ligand basicity order and also the metal ion electron affinities as measured by their ionization potential. The stability constants of the metal complexes follow the order: Cu^(II) > Zn^(II) > Ni^(II) > Mn^(II) > Hg^(II) > Cd^(II).     

Photoinitiated Thiol−Ene Reactions of Various 2,3‐Unsaturated O‐, C‐ S‐ and N‐Glycosides – Scope and Limitations Study

The photoinitiated thiol?ene addition reaction is a highly stereo‐ and regioselective, and environmentally friendly reaction proceeding under mild conditions, hence it is ideally suited for the synthesis of carbohydrate mimetics. A comprehensive study on UV‐light‐induced reactions of 2,3‐unsaturated O‐, C‐, S‐ and N‐glycosides with various thiols was performed. The effect of experimental parameters and structural variations of the alkenes and thiols on the efficacy and regio‐ and stereoselectivity of the reactions was systematically studied and optimized. The type of anomeric heteroatom was found to profoundly affect the reactivity of 2,3‐unsaturated sugars in the thiol?ene couplings. Hydrothiolation of 2,3‐dideoxy O‐glycosyl enosides efficiently produced the axially C2‐S‐substituted addition products with high to complete regioselectivity. Moderate efficacy and varying regio‐ and stereoselectivity were observed with 2,3‐unsaturated N‐glycosides and no addition occurred onto the endocyclic double bond of C‐glycosides. Upon hydrothiolation of 2,3‐unsaturated S‐glycosides, the addition of thiyl radicals was followed by elimination of the thiyl aglycone resulting in 3‐S‐substituted glycals.     

Sensing of Fe(III) ion via turn-on fluorescence by fluorescence probes derived from 1-naphthylamine

Fluorescence probes NA1 and NA2 derived from 1-naphthylamine (NA) as fluorophore have been synthesized and characterized by different spectroscopic studies. Identification behaviour of these probes towards various metal ions has been investigated. Both the fluorescent probes are selective as well as sensitive towards Fe(III) ion. Novel fluorescence probe NA2 afforded turn-on fluorescence behaviour for Fe(III) ion over other metal ions such as Ca(II), Mg(II), Mn(II), Fe(II), Co(II), Fe(III), Ni(II), Cu(II), Zn(II) and Hg(II).     

On non-negligible bias of the first output byte of RC4 towards the first three bytes of the secret key

In this paper, we show that the first byte of the keystream output of RC4 has non-negligible bias towards the sum of the first three bytes of the secret key. This result is based on our observation that the index, where the first byte of the keystream output is chosen from, is approximately twice more likely to be 2 than any other value. Our technique is further used to theoretically prove Roos’s experimental observation (A class of weak keys in the RC4 stream cipher, 1995) related to weak keys.     

Microwave performance enhancement in Double and Single Gate HEMT with channel thickness variation

In Single Gate HEMT (SGHEMT) shortening of gate length (_Lg)$\left(L_g\right)$ below 100 nm leads to reduction in Transconductance (_gm)$\left(g_m\right)$, which reduces the unloaded voltage gain (_gm/_gd)$(g_m/g_d)$ of the device, thereby reducing the maximum frequency of oscillation (_fmax)$\left(f_{max}\right)$. The main reason for this reduction in _gm$g_m$ with _Lg$L_g$ in the Single Gate HEMT (SGHEMT) is its inability to maintain the desired channel aspect ratio (α$\alpha$). At such a miniaturization level, α$\alpha$ not only depends on the channel depth (d)$\left(d\right)$ but also on the channel thickness (_dc)$\left(d_c\right)$ of the device [5]. Moreover, the variation of _dc$d_c$ may switch the device characteristics from quantum regime to classical regime  and . The Double Gate HEMT (DGHEMT)  and  has emerged as a solution for further reduction in _Lg$L_g$ and provides enhancements over SGHEMT by virtue of its double gate and also for same _dc$d_c$ due to double heterojunctions, which virtually increases the value of α$\alpha$. In the present work, extensive simulation work has been carried out using ATLAS device simulator [35] in order to study the effect of _dc$d_c$ and _Lg$L_g$ on DGHEMT and SGHEMT. An analytical model has also been proposed for SGHEMT and DGHEMT to incorporate the effect of variation of _dc$d_c$ and _Lg$L_g$.     

Highly Efficient Glutathione Peroxidase and Peroxiredoxin Mimetics Protect Mammalian Cells against Oxidative Damage

Novel isoselenazoles with high glutathione peroxidase (GPx) and peroxiredoxin (Prx) activities provide remarkable cytoprotection to human cells, mainly by exhibiting antioxidant activities in the presence of cellular thiols. The cytotoxicity of the isoselenazoles is found to be significantly lower than that of ebselen, which is being clinically evaluated by several groups for the treatment of reperfusion injuries and stroke, hearing loss, and bipolar disorder. The compounds reported in this paper have the potential to be used as therapeutic agents for disorders mediated by reactive oxygen species.