Robust sampled‐data H∞ control for mechanical systems

This article addresses the issue of robust sampled‐data control for a class of uncertain mechanical systems with input delays and linear fractional uncertainties which appear in all the mass, damping, and stiffness matrices. Then, a novel Lyapunov–Krasovskii functional is constructed to obtain sufficient conditions under which the uncertain mechanical system is robustly, asymptotically stable with disturbance attenuation level about its equilibrium point for all admissible uncertainties. More precisely, Schur complement and Jenson's integral inequality are utilized to substantially simplify the derivation of the main results. In particular, a set of sampled‐data controller is designed in terms of the solution of certain linear matrix inequalities that can be solved effectively using available MATLAB software. Finally, a numerical example with simulation result is provided to show the effectiveness and less conservativeness of the proposed sampled‐data control scheme. © 2014 Wiley Periodicals, Inc. Complexity 20: 19–29, 2015     

Raman Imaging: An Impending Approach Towards Cancer Diagnosis

In accordance with the recent studies, Raman spectroscopy is well experimented as a highly sensitive analytical and imaging technique in biomedical research, mainly for various disease diagnosis including cancer. In comparison with other imaging modalities, Raman spectroscopy facilitate numerous assistances owing to its low background signal, immense spatial resolution, high chemical specificity, multiplexing capability, excellent photo stability and non-invasive detection capability. In cancer diagnosis Raman imaging intervened as a promising investigative tool to provide molecular level information to differentiate the cancerous vs non-cancerous cells, tissues and even in body fluids. Anciently, spontaneous Raman scattering is very feeble due to its low signal intensity and long acquisition time but new advanced techniques like coherent Raman scattering (CRS) and surface enhanced Raman scattering (SERS) gradually superseded these issues. So, the present review focuses on the recent developments and applications of Raman spectroscopy-based imaging techniques for cancer diagnosis.     

Synthesis and solution properties of comblike polymers from octadecyl methacrylate and acrylic acid

Amphiphilic polymers consisting of a statistical distribution of octadecyl methacrylate (ODMA) and acrylic acid in respective molar ratios of 83-22 and 17-78 mol% and in a molecular-weight range of 2.35-4.70᎒⁴ gmol^-1 have been synthesized. The series of polymers consisting of various mole fractions of ODMA and acrylic acid are expected to exhibit unique characteristics resembling ionomer to hydrophobically modified polyelectrolytes. The changes in the I₃/I₁ emission intensity ratios of pyrene, occurring in the presence of tetrahydrofuran (THF) solutions of the polymers have been taken as the main basis for inferring solution structures. The polymers are found to form random-coil to collapsed-coil/aggregated structures in THF solvent depending on the copolymer compositions. The polymer consisting of 83 mol% ODMA and 17 mol% acrylic acid behaves as an ionomer, capable of forming collapsed-coil structures at concentrations of 0.02 gml^-1 and above as shown by a very high I₃/I₁ of 1.20 (I₃/I₁ of pyrene in THF is 0.85). In contrast, the poly(octadecyl methacrylate) homopolymer and the sets of copolymers consisting of a very high proportion of acrylic acid to an extent of 73 mol% and above contribute to almost negligible or very small changes in I₃/I₁ similar to the homopolymer, poly(octadecyl methacrylate), suggesting the formation of random-coil structures.     

Ultrasound assisted,VOSO4 catalyzed synthesis of 4-thiazolidinones: Antimicrobial evaluation of indazole-4-thiazolidinone derivatives

A simple and expedient multicomponent protocol was developed to synthesize 4-thiazolidinones by employing VOSO₄ as a catalyst under ultrasonic irradiation. The significant features of this protocol includes shorter reaction time, high yields, low catalyst loading, and also the catalyst can be recovered and reused up to next four cycles without significant loss in catalytic activity. All the synthesized novel indazole compounds were evaluated for their antibacterial and anti-biofilm activities. Compounds 9n, 9o and 9q showed promising activity (MIC value of 3.9?µg/mL) against K. planticola (MTCC 530). They also exhibited significant bactericidal activity against K. planticola (MTCC 530) (MBC value of 15.6?µg/mL). Additionally, 9n, 9o and 9q inhibited biofilm formation (IC₅₀ values ranging between 20.28–20.79?μg/mL) in this organism.     

Calcium Alginate Bead-mediated Enhancement of the Selective Recovery of a Lead Novel Antifungal Bacillomycin Variant

In the pursuit of new antifungal compounds, five coproduced lipopeptide variants (AF₁ to AF₅) from wild-type Bacillus subtilis RLID 12.1 were identified in our previous study. Out of five, AF₄ was identified as a novel lead molecule belonging to the bacillomycin family showing less cytotoxicity at its respective minimum inhibitory concentrations (MIC) evaluated against 81 strains of Candida and Cryptococcus species (including clinical isolates); besides this, AF₄ purified in the present study exhibited encouraging MIC values against 10 clinical mycelial fungi. Aiming for a selective production augmentation of AF₄ lipopeptide variant, a new fermentation media comprising malt extract (1.01%), dextrose (0.55%), peptone (1.79%), MnSO₄ (2 mM), and NaCl (0.5%) was formulated. Maximum production of 954.8?±?10.8 mg/L was achieved with 44% selectivity at 30 °C compared to unoptimized conditions (186.4?±?6.1 mg/L). Use of calcium alginate beads in the formulated media during the onset of lipopeptide production resulted in an augmentation in the selectivity of the most efficacious AF₄ variant to about 72% presumably due to attenuation of other coproduced lipopeptide variants AF₁ and AF₂. Difference in yield of lipopeptides varied with bead size, bead preparation ratios, and sodium alginate concentrations. Use of Ca-alginate beads in the upstream production process of the lead AF₄ variant may be considered as a novel strategy to address the potential challenge that may arise during the scale-up and downstream processing steps. Another significant finding derived from the study is that the proportion of bacillomycin variants of B. subtilis RLID 12.1 could be controlled by temperature and metal ions under static and shaking conditions.     

Raman spectroscopic study of medieval Indian art of 17th century

We report the first Raman spectroscopic investigations of medieval Indian art of 17th century. Three miniature paintings, belonging to Mogul and Rajput schools from the collections of the Madras Museum, were investigated by micro‐Raman spectroscopy using different excitation wavelengths. Many areas in the paintings exhibited rich spectra containing several intense Raman bands. The Raman bands were assigned on the basis of the reported reference spectra of the pigments. Evidences for the presence of massicot, red‐lead, lead‐white, vermilion, litharge, Indian yellow and anatase are found. In addition, tentative assignments of some of the Raman bands to atacamite and orpiment are also made. The present studies suggest that several mineral‐based unique pigments were popular among the Indian artists of this period. Copyright © 2010 John Wiley & Sons, Ltd.     

Structural and electrical conductivity studies of Li x AlZr[PO4]3 (x = 1.8, 2.0, 2.2), solid electrolyte for lithium-rechargeable batteries

In the present study, Li _x AlZr[PO₄]₃ (x = 1.8, 2.0, 2.2) has been prepared by the Pechini-type polymerizable precursor method, and structural and electrical analyses have been performed. Formation of the compound has been confirmed from X-ray diffraction pattern. Vibrational analysis has been performed using Fourier transform infrared spectroscopy. Ion transport mechanism has been analyzed using the AC impedance technique. Electrical characterization reveals that the maximum conductivity (4.4 × 10^?5S cm^?1) has been observed for the sample Li_2.2AlZr[PO₄]₃ at 673K.     

Practical and Chemoselective Reduction of Acyl Chloride to Alcohol by Borohydride in Aqueous Dichloromethane

A simple methodology for the reduction of acid chlorides to their corresponding alcohols has been developed. Various carboxylic acids were converted to alcohols in excellent yields using NaBH₄-K₂CO₃ in a mixed solvent system of dichloromethane and water (1:1) in the presence of a phase-transfer catalyst at low temperature. The importance of the work is its simplicity, selectivity, excellent yield, and very short reaction time. This new reduction condition has proved to be an excellent chemoselective method for a range of acid chlorides in the presence of various functional groups.