Microstructure determination of isobornyl methacrylate-styrene copolymer by NMR spectroscopy

An investigation of the microstructure of isobornyl methacrylate - styrene (I/S) copolymers prepared by the atom transfer radical polymerization (ATRP) using methyl-2-bromopropionate as an initiator and PMDETA copper complex as catalyst under nitrogen atmosphere at 70 °C has been done by two-dimensional NMR techniques. 2D- HSQC and TOCSY have been utilized to resolve the complex ¹H NMR spectrum and to establish the compositional and configurational sequences of isobornyl methacrylate-styrene (I/S) copolymers. 2D HSQC and TOCSY spectra showed compositional and configurational sensitivity of α-methyl carbon of I unit and methine proton of S unit and are assigned up to the triad level. The methylene carbon (C₁₀) also shows triad level of compositional sensitivity in 2D HSQC spectra. Heteronuclear multiple-bond correlation (HMBC) spectroscopy has been used to study carbonyl/quaternary carbon-proton coupling. The carbonyl and quaternary carbons showed compositional and configurational sensitivity upto the triad level. The values of reactivity ratios were determined by Kelen-Tudos (KT) and nonlinear error in variable method (RREVM) using copolymer composition data that were determined by ¹H NMR spectrum. Reactivity ratios of co-monomers in I/S copolymer, determined from a linear Kelen-Tudos method (KT) and non-linear Error-in-Variable Method (EVM), are r_I?=?0.39?±?0.09, r_S?=?0.44?±?0.08 and r_I?=?0.42, r_S?=?0.47, respectively.     

A multiplex PCR assay based on 16S rRNA and hly for rapid detection of L. monocytogenes in Milk

A multiplex PCR assay was developed by targeting ‘16S rRNA’ and ‘hly’ genes for detection of Listeria or Listeria monocytogenes in dairy foods on the basis of amplification of 1200 and 713 bp products, respectively. The assay conditions were optimized to make it truly rapid and to cut down the cost. The authenticity of the multiplex PCR was ascertained by using Nested PCR targeted against internal region of ‘hly’ gene that produced an amplified product of 188 bp. The multiplex PCR assay was found to be specific for detection of L. monocytogenes only since none of the non-listerial cultures gave positive signal. The sensitivity of the multiplex PCR was limited to 10 ng pure DNA and 1–10 cells of L. monocytogenes after 4–6 h enrichment in Listeria enrichment broth. When applied to 20 raw milk and 10 pasteurized milk samples, L. monocytogenes could not be detected in any of the samples by the multiplex PCR assay. This assay could find potential application in dairy industry for monitoring dairy foods for this high risk food pathogen on routine basis.     

Effect of fluid viscosity on wave propagation in a cylindrical bore in micropolar elastic medium

Wave propagation in a cylindrical bore filled with viscous liquid and situated in a micropolar elastic medium of infinite extent is studied. Frequency equation for surface wave propagation near the surface of the cylindrical bore is obtained and the effect of viscosity and micropolarity on dispersion curves is observed. The earlier problems of Biot and of Banerji and Sengupta have been reduced as a special case of our problem.     

Critical Behavior of Ferromagnetic Transition in SnO2-Based Diluted Magnetic Semiconductor

Isothermal magnetization data in the critical region of the ferromagnetic transition for Co-doped SnO₂-based diluted magnetic semiconductor were measured and analyzed in terms of the modified Arrott plot method and, independently by the Kouvel–Fisher method. The critical exponents β,γ, and δ, corresponding to spontaneous magnetization, initial susceptibility and isothermal magnetization, respectively, were determined and the values are found to be comparable to the mean-field model. The critical exponent values are found to be consistent with the Widom scaling relation and the universal scaling hypothesis. The temperature variation of the effective critical exponent is found to show the characteristic behavior of a disordered system.     

iDiff: Informative Summarization of Differences in Multidimensional Aggregates

Multidimensional OLAP products provide an excellent opportunity for integrating mining functionality because of their widespread acceptance as a decision support tool and their existing heavy reliance on manual, user-driven analysis. Most OLAP products are rather simplistic and rely heavily on the user's intuition to manually drive the discovery process. Such ad hoc user-driven exploration gets tedious and error-prone as data dimensionality and size increases. Our goal is to automate these manual discovery processes. In this paper we present an example of such automation through a iDiff operator that in a single step returns summarized reasons for drops or increases observed at an aggregated level.We formulate this as a problem of summarizing the difference between two multidimensional arrays of real numbers. We develop a general framework for such summarization and propose a specific formulation for the case of OLAP aggregates. We develop an information theoretic formulation for expressing the reasons that is compact and easy to interpret. We design an efficient dynamic programming algorithm that requires only one pass of the data and uses a small amount of memory independent of the data size. This allows easy integration with existing OLAP products. Our prototype has been tested on the Microsoft OLAP server, DB2/UDB and Oracle 8i. Experiments using the OLAP benchmark demonstrate (1) scalability of our algorithm as the size and dimensionality of the cube increases and (2) feasibility of getting interactive answers with modest hardware resources.     

Preparation and characterization of composites of polypyrrole

In this paper, we report the preparation and characterization of composites of polypyrrole (PPy) with polyvinylidene fluoride (PVDF), and cellulose. We used the techniques of chemical and electrochemical polymerization. These materials were characterized using X-ray diffraction (wide and small angle (SAXS)), electrical conductivity and electron microscopy. The studies showed that homogeneous composites could be formed. The percentage crystallinity of the host polymer decreased, whereas some crystallization of PPy was noticed. SAXS studies revealed that the diffusion of PPy is in amorphous regions. The electrical conductivity of the composites was found to vary in the range of 10^?8 S/cm to 10^?4 S/cm. These composites were found to be useful in gas sensors for detection of chlorine and ammonia.     

Reflection of plane waves in a thermoelastic diffusive medium under the effect of microtemperatures

Abstract

The present analysis is aimed to model and study the characteristics of various reflected waves in a homogeneous and isotropic thermoelastic diffusive half-space with microtemperatures. It is shown that there exist four kinds of coupled longitudinal waves in addition to transverse and microtemperature waves in such type of medium. The reflection coefficients and energy ratios of these reflected waves have been computed numerically with the help of MATLAB programing when (i) a set of coupled longitudinal waves is made incident and (ii) a transverse wave is made incident. The numerical values of modulus of reflection coefficients are presented graphically to depict the effect of thermodiffusive parameter. It has been verified that there is no dissipation of energy at the free plane boundary during reflection phenomena.     

Production and properties of crude enterotoxin of Pseudomonas aeruginosa

Pseudomonas aeruginosa CTM-3 was found to be the most potentially enteroxigenic strain out of the 12 isolates recovered from milk, as a high fluid length ratio, i.e. F/L (1.1) in rabbit gut and a strong permeability response in rabbit skin (38.5 mm² necrotic zone) was obtained with this culture. No clear-cut relationship between the two tests was observed. Six of the ethidium bromide (300 μg/ml) cured variants of this culture completely lost their ability to produce enterotoxin indicating the possible involvement of a plasmid in enterotoxin synthesis. The crude enterotoxin from P. aeruginosa CTM-3 was completely inactivated in 15 s at 72°C. However, it was fairly stable at pH values in the range 4.5–7.5. Both pepsin and trypsin inactivated the enterotoxin activity at a concentration of 40 μg/ml. Organic acids, formalin and hydrogen peroxide had no significant effect on the enterotoxin activity. The need for further investigations with purified preparations is emphasized.     

Synthesis of PEDOT:PSS (poly(3,4‐ethylenedioxythiophene))/poly(4‐styrene sulfonate))/ ngps (nanographitic platelets) nanocomposites as chemiresistive sensors for detection of nitroaromatics

Polymer nanocomposites (NCs) are a special class of materials having unique properties and wide application potential in electronics and other diverse areas. In this study, NCs consisting of poly(3,4‐ethylenedioxythiophene)/poly(4‐styrene sulfonate) (PEDOT:PSS) matrix reinforced with graphite nanosheets were fabricated by solution method. The graphite used was functionalized before fabrication of NCs. The functionalized graphite was characterized by transmission electron microscopy (TEM) and Fourier transform Infrared spectroscopy (FTIR) technique. The NCs prepared were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR technique. The conductivity studies of the prepared NCs were carried out. The prepared NCs films were investigated for the detection of nitrobenzene vapors. The detection mechanism is based on measuring resistivity changes that occur in a NC due to the absorption of nitrobenzene vapors by PEDOT:PSS film. These sensors exhibited excellent response at room temperature when exposed to vapors of nitrobenzene. Sensitivity as high as 18.5% was observed for PEDOT:PSS/NGPs composite. The chemresistor exhibits a fast response (～1.14 min) and good recovery time (～1–2 min). The response of NC to the nitrobenzene vapors is reproducible. POLYM. ENG. SCI., 53:2045–2052, 2013. © 2013 Society of Plastics Engineers