Manju Bala

Novel peptidomimics as angiotensin-converting enzyme inhibitors: a combinatorial approach.

One of the efficient mode of treatments of chronic hypertension and cardiovascular disorders has been to restrain the formation of angiotensin-II by inhibiting the action of angiotensin-converting enzyme (ACE) on angiotensin-I. A number of ACE inhibitors (ACEIs) have been put to therapeutic use during the last two decades. The efforts continue towards achieving superior molecules or drugs with improved affinities, better bioavailability and thus long duration of action with minimum side effects. The present work evolves around similar objectives. In order to understand the mode of interaction of inhibitors with the active site of the enzyme and subsequently to have lead compounds as possible inhibitors the novel dipeptidomimics and tripeptidomimics have been designed and synthesized using combinatorial chemistry approach. A Focussed library of 10 di- and tri-peptides, eight dipeptidomemics and forty tripeptidomemics was generated. The pharmacophoric heterocyclic moieties and the amino acids have been selected to have affinities with the S1, S1, and S2 subsites of the active site of the enzyme. ACE inhibition studies clearly demonstrated the structural-activity relationships within these classes of peptidomimics. The dipeptidomimics interacted only with S1 and S2 subsites, whereas the tripeptidomemics had additional interaction with S1 subsite, which accounted for their significant ACE inhibition potencies. The in-vitro screening of these peptidomimics have resulted in identification of four promising tripeptidomimics 34[2-benzimidazolepropionyl-Val-Trp], 35[5hydroxytryptophanyl-Val-Trp], 40[2-benzimidazolepropionyl-Ile-Trp] and 45[2-benzimidazolepropionyl-Lys-Trp] with IC50 values in micromolar concentrations.

An experimental setup for the simultaneous measurement of thermoelectric power of two samples from 77 K to 500 K

We report on an experimental setup for the simultaneous measurement of the thermoelectric power (TEP) of two samples in the temperature range from 77 K to 500 K using optimum electronic instruments. The setup consists of two rectangular copper bars in a bridge arrangement for sample mounting, two surface mount (SM) chip resistors for creating alternate temperature gradient, and a type E thermocouple in differential geometry for gradient temperature (ΔT) measurement across the samples. In addition, a diode arrangement has been made for the alternate heating of SM resistors using only one DC current source. The measurement accuracy of ΔT increases with the differential thermocouple arrangement. For the calibration of the setup, measurements of TEP on a high purity (99.99%) platinum wire and type K thermocouple wires Chromel and Alumel have been performed from 77 K to 500 K with respect to copper lead wires. Additionally, this setup can be utilized to calibrate an unknown sample against a sample of known absolute TEP.

Enhancement of thermoelectric power of PbTe:Ag nanocomposite thin films

The present study focuses on the enhancement of thermoelectric power of PbTe:Ag nanocomposite thin films, synthesized by the thermal evaporation technique. Thermoelectric measurements were carried out from room temperature to 400 K. It is observed that Ag addition improves the thermoelectric power and crystalline nature of the PbTe thin films. Synchrotron based X-ray diffraction was performed to confirm the phases of the Pb–Ag–Te alloy. This was further reconfirmed by X-ray photoelectron spectroscopy (XPS) and showed the precipitation of Pb on the surface of the PbTe:Ag films. The enhancement of thermoelectric power is thus attributed to the formation of Ag2−xTe alloy and the precipitation of Pb nanostructures on the surface. The origin of such enhancement is understood based on the phenomenon of energy dependent filtering of charge carriers.

Phase evolution and electrical properties of Co–Sb alloys fabricated from Co/Sb bilayers by thermal annealing and ion beam mixing

An investigation was carried out to understand the phase evolution and study the structural, morphological, optical and electrical properties of Co-Sb alloys fabricated by two different approaches: (a) thermal annealing and (b) ion-beam mixing followed by post annealing. The as-deposited and 100 MeV Ag ion beam irradiated Co/Sb bilayer thin films were subjected to thermal annealing from 200 to 400 °C for 1 hour. The Rutherford backscattering spectrometry (RBS) results showed partial mixing for the thermally annealed films and complete mixing for the irradiated and post annealed films at 400 °C. The XRD and RAMAN measurements indicated the formation of Co-Sb alloy, with ∼70% concentration of CoSb3 phase in the irradiated post annealed sample at 400 °C. The band gaps of the annealed and post irradiated annealed Co-Sb alloys were determined using UV-visible spectroscopy. Electrical and thermoelectric power measurements were performed in the temperature range of 300-420 K. It was observed that the alloys formed by ion-beam induced mixing exhibited higher electrical conductivity and thermoelectric power than the as-deposited and thermally annealed Co/Sb bilayer thin films.

Enhancement of thermoelectric power of PbTe thin films by Ag ion implantation

Enhancement of the figure of merit (ZT) of thermoelectric materials is the topic of current research in energy studies. We report an enhancement in the thermoelectric power (TEP) of thermally evaporated PbTe thin films by low energy Ag ion implantation. This implantation results in PbTe:Ag nanocomposites. Implantations were carried out at a 130u2009keV Ag ion beam with ion fluences of 3u2009×u20091015, 1.5u2009×u20091016, 3u2009×u20091016, and 4.5u2009×u20091016 ions/cm2. The atomic concentrations were determined using Rutherford backscattering and found to be 1u2009at. %, 5u2009at. %, 10u2009at. %, and 14u2009at. % in the implanted PbTe films. Scanning electron microscopy images show the presence of fine cracks on the surface of as-deposited PbTe thin films that get shortened and suppressed and finally disappear at higher fluences of Ag ion implantation. The TEP measurements, from 300u2009K to 400u2009K, show ∼25% enhancement in the Seebeck coefficient of the Ag ion implanted films in comparison to the pristine PbTe thin film. The synchrotron based high resolutio...

Orthometallation in bidentate Schiff base ligands via C–H activation: synthesis of ruthenium(III) organometallic complexes

AbstractnSchiff bases obtained by the reactions of substituted aromatic aldehydes with phenyl hydrazine or 2,4-dinitrophenyl hydrazine were synthesized and characterized by spectroscopic methods. Cyclometalated Ru(III) complexes of general formula, namely [Ru(L)(PPh3)2Cl], were synthesized from the Schiff bases via C–H bond activation and characterized by spectroscopic and electrochemical studies. In addition, one molecular structure of one of the complexes was determined by X-ray crystallography. The redox behavior of the complexes was examined by electrochemical studies, and one mechanism of orthometallation was investigated.Graphical Abstract

Synthesis and characterization of Au–Fe alloy nanoparticles embedded in a silica matrix by atom beam sputtering

In the present study, we investigated the formation of AuFe alloy nanoparticles embedded in a silica matrix by the cosputtering of silica, Au and Fe with two different metal fractions using an atom beam source. The increase in the metal fraction in the thin film results in the formation of AuFe alloy nanoparticles. The absence of surface plasmon resonance peak for the Au nanoparticles in the optical spectra, structural studies and transmission electron microscopy results confirmed the existence of AuFe alloy nanoparticles. The nanocomposite is ferromagnetic at 2 K with a symmetric hysteresis loop. The formation of AuFe alloy nanoparticles in the thin film is explained on the basis of interatomic distance and diffusion during deposition.

Dynamic frequency based parallel k-bat algorithm for massive data clustering (DFBPKBA)

In the past one decade there has been significant increase in the growth of digital data. Therefore, good data mining techniques are important for the better decision making. Clustering is one of the key element in the field of data mining. K-means is a very popular algorithm present in the literature which is widely used for the clustering purpose. However k-means algorithm suffers from the problem of stucking into local optimum solution because of it’s dependency on the random initialization of initial cluster center. In this paper a novel variant of Bat algorithm based on dynamic frequency is introduced. Further the proposed variant is hybridized with K-means to present a new approach for clustering in distributed environment. Since evolutionary computation is very computation intensive, traditional sequential algorithms are not able to provide satisfactory results within the reasonable amount of time for the large scale data problems. To mitigate this problem the proposed variant is parallelized using the MapReduce model in the Hadoop framework. The experimental results show that the proposed algorithm has outperformed K-means, PSO and Bat algorithm on eighty percent of the benchmark datasets in terms of intra-cluster distance. Further DBPKBA has also achieved significant speedup for dealing with massive datasets with increase in the number of nodes.

Site-specific orthometallation via C–H bond activation and syntheses of ruthenium(III) organometallics: studies on nitric oxide (NO) reactivity and photorelease of coordinated NO

A new family of σ-aryl ruthenium(III) complexes [Ru(L1–4)(PPh3)2Cl] (1–4) (where L1H2 = N-(quinolin-8-yl)benzamide for 1, L2H2 = 4-chloro-N-(quinolin-8-yl)benzamide for 2, L3H2 = 4-nitro-N-(quinolin-8-yl)benzamide for 3, L4H2 = 3-nitro-N-(quinolin-8-yl)benzamide for 4 and H = dissociable protons) derived from bidentate ligands having amide bonds was synthesized through C–H bond activation. These organometallic ruthenium(III) complexes were treated with nitric oxide (NO) to afford the nitrosyl complexes [Ru(NO2L1–4)(PPh3)2(NO)](ClO4) (1a–4a) (where NO2L1H2 = N-(5-nitroquinolin-8-yl)benzamide for 1a, NO2L2H2 = 4-chloro-N-(5-nitroquinolin-8-yl)benzamide for 2a, NO2L3H2 = 4-nitro-N-(5-nitroquinolin-8-yl)benzamide for 3a, NO2L4H2 = 3-nitro-N-(5-nitroquinolin-8-yl)benzamide for 4a and H = dissociable protons). All ruthenium complexes were characterized by various spectroscopic techniques. An X-ray crystallographic study afforded the molecular structure of complex 4a and the site-specific orthometallation was scrutinized. The coordinated NO molecule was found to be photolabile under visible and UV light.

Designing ANFIS Model to Predict the Reliability of Component-Based System

Predicting reliability of any product is always a desire of quality-oriented industry. The fault-free working of products depends on large number of parameters, and designing a machine learning model that can predict the reliability considering these as input parameters will help to plan testing and maintenance of the product. In this paper, ANFIS approach is adopted to train a model that can predict reliability of component-based software system. The parameters considered for designing the model are standard design metrics which are evaluated for quality benchmarking during software development process.