Molecular Epidemiological Study of Pyrazinamide-Resistance in Clinical Isolates of Mycobacterium tuberculosis from South India

Pyrazinamide (PZA) has been in use for almost 50 years as a first-line drug for short-course chemotherapy against Mycobacterium tuberculosis. In this study, PCR mediated automated DNA sequencing is used to check the prevalence of PZA resistance among treatment failure cases of pulmonary tuberculosis. Out of 50 clinical isolates examined, 39 had mutations in the pncA gene that encodes Pyrazinamidase, an enzyme required to activate PZA. Of these, 31 (79.5%) were localized to three regions of pncA. We found two isolates with hitherto unreported mutation at amino acid 26 (Ala→Gly) of pncA.     

Dishing and nitride erosion of STI-CMP for different integration schemes

In this paper, we investigate the effects of integration schemes on the STI-CMP performance of two polishers, as well as the influence of consumables and process parameters. The experiment was based on both the blanket-oxide wafers and the patterned wafers processed using 0.18 μm technology. The polishing capability was evaluated, based on the results collected using metrology tools such as Opti-probe, Tencor profiler; atomic force microscope (AFM), and x-ray-scanning electron microscopy (X-SEM) analysis.     

Integrated analytical models for flexible manufacturing systems

Product form queueing networks (pfqn) and generalized stochastic Petri nets (gspn) have emerged as the principal performance modelling tools for flexible manufacturing systems (fms). In this paper, we present integratedpfqn-gspn models, which combine the computational efficiency ofpfqn and representational power ofgspn by employing the principle of flow-equivalence. We show thatfms that include nonproduct form characteristics such as dynamic routing and synchronization can be evaluated efficiently and accurately using the integrated models.     

Surfactant‐mediated synthesis of polyhydroxybutyrate (PHB) nanoparticles for sustained drug delivery

In this study, polyhydroxybutyrate (PHB) nanoparticles were synthesised following nanoprecipitation method having different solvents and surfactant (Tween 80) concentrations. In this study, PHB nanoparticles were encapsulated with curcumin and subjected for sustained curcumin delivery. Both the curcumin loaded and unloaded PHB nanoparticles were characterised using FTIR, SEM, and AFM. Sizes of the particles were found to be between 60 and 300 nm. The drug encapsulation efficiency and in vitro drug release of the nanoparticles were analysed. Antibacterial activity and anticancer activity were also evaluated. The LC₅₀ values of most of the nanoparticles were found to be between 10 and 20 µg/100 µl, anticancer activity of curcumin loaded PHB nanoparticles were further confirmed by AO/PI staining and mitochondrial depolarisation assay.Inspec keywords: encapsulation, cancer, scanning electron microscopy, nanoparticles, surfactants, drugs, nanofabrication, antibacterial activity, biomedical materials, drug delivery systems, polymers, nanomedicine, Fourier transform infrared spectra, precipitation (physical chemistry), atomic force microscopy, particle sizeOther keywords: surfactant‐mediated synthesis, polyhydroxybutyrate nanoparticles, sustained drug delivery, surfactant concentrations, PHB nanoparticles, sustained curcumin delivery, drug encapsulation efficiency, anticancer activity, in vitro drug release, nanoprecipitation method, Tween 80, FTIR spectra, SEM, AFM, particle sizes, antibacterial activity, AO‐PI staining, mitochondrial depolarisation assay     

A novel zeolite-multiwalled carbon nanotube composite for the electroanalysis of copper(II) ion

The application of zeolite Y-multiwalled carbon nanotube (MWCNT) nanocomposite modified glassy carbon electrode (zeolite Y-MWCNT/GCE) in the electroanalysis of Cu²⁺ ion is presented. In order to bring out the unique advantage of the zeolite Y-MWCNT/GCE, experiments were carried out also at graphite/GCE, MWCNT/GCE and zeolite Y-graphite/GCE. For the same surface area, the performance of zeolite Y-MWCNT/GCE was superior to the other modified electrodes in terms of current sensitivity for Cu²⁺ ion. The combination of zeolite Y and MWCNT as a nanocomposite resulted in a good synergetic effect. The Cu⁺² ion sensor exhibited a linear calibration range between 5 × 10⁻⁸ and 1 × 10⁻⁵ mol L⁻¹ with a detection limit of 1.12 × 10⁻⁸ mol L⁻¹ (0.72 ppb).     

Investigation on natural radiation level and its hazardous nature of river sediments using γ-ray spectroscopy

The content of natural radionuclides (²³⁸U, ²³²Th, ⁴⁰K) in sediment samples of Ponnaiyar River, taken from different depths, were determined using a γ-ray spectroscopic system with a NaI(TI) detector with an aim of evaluating the radiation hazard. The results are compared with Indian and world average values. To know the complete radiological characteristics, the radiological indices such as absorbed dose rate, annual effective dose equivalent (indoor and outdoor), radium equivalent activity, hazard index (H _ex and H _in), γ-index, activity utilization index, and excess lifetime cancer risk were calculated. The results obtained were discussed and compared with the recommended values. The outdoor γ-dose rates were measured at each sampling site using an environmental radiation dosimeter. The measured results were compared with literature values and correlated with the calculated absorbed dose rate. Averages of all the radiation hazard indices and concentrations of all the measured radionuclides in all the layers are lower than the recommended level. The origin of the detected radionuclides is assessed by comparing the present results with the corresponding values for the earth crust and other rock formations.     

Effect of Hydrogen and Magnetic Field on the Mechanical Behavior of High Strength AISI 4340 Steel

Presence of hydrogen in materials is known to affect their mechanical properties due to hydrogen embrittlement problem. Steels used in various applications are prone to be exposed to aqueous electrochemical environments, which may introduce hydrogen into the alloy. These alloys are also prone to be simultaneously exposed to magnetic field, which may affect the hydrogen embrittlement susceptibility of these alloys. Therefore, it is important to examine the effect of hydrogen and magnetic field on the mechanical behavior of iron-based alloys. In this work, the effect of hydrogen and magnetic field on the fracture behavior of high strength AISI 4340 steel was examined. Three-point bend test was used to study the fracture behavior. In all the cases, the samples tested with hydrogen charging show a drastic reduction in ductility and fracture stress values. The effect of magnetic field was seen to be negligible. The hydrogen embrittlement was characterized by a change in the fracture surface from a ductile-type fracture to a brittle cleavage-type fracture. Acoustic emission signals collected during the test corresponds to the fracture behavior.     

Solvothermal‐assisted green synthesis of hybrid Chi‐Fe3 O4 nanocomposites: a potential antibacterial and antibiofilm material

In this present study, a hybrid Chi‐Fe₃ O₄ was prepared, characterised and evaluated for its antibacterial and antibiofilm potential against Staphylococcus aureus and Staphylococcus marcescens bacterial pathogens. Intense peak around 260 nm in the ultraviolet–visible spectrum specify the formation of magnetite nanoparticles. Spherical‐shaped particles with less agglomeration and particle size distribution of 3.78–46.40 nm were observed using transmission electron microscopy analysis and strong interaction of chitosan with the surface of magnetite nanoparticles was studied using field emission scanning microscopy (FESEM). X‐ray diffraction analysis exhibited the polycrystalline and spinel structure configuration of the nanocomposite. Presence of Fe and O, C and Cl elements were confirmed using energy dispersive X‐ray microanalysis. Fourier transform infrared spectroscopic analysis showed the reduction and formation of Chi‐Fe₃ O₄ nanocomposite. The antibacterial activity by deformation of the bacterial cell walls on treatment with Chi‐Fe₃ O₄ nanocomposite and its interaction was visualised using FESEM and the antibiofilm activity was determined using antibiofilm assay. In conclusion, this present study shows the green synthesis of Chi‐Fe₃ O₄ nanocomposite and evaluation of its antibacterial and antibiofilm potential, proving its significance in medical and biological applicationsInspec keywords: visible spectra, particle size, magnetic particles, nanocomposites, nanoparticles, X‐ray diffraction, nanofabrication, transmission electron microscopy, X‐ray chemical analysis, nanomagnetics, microorganisms, antibacterial activity, iron compounds, ultraviolet spectra, biomedical materials, field emission scanning electron microscopy, Fourier transform infrared spectra, filled polymers, crystal growth from solution, polymer structureOther keywords: potential antibacterial material, antibiofilm potential, magnetite nanoparticles, solvothermal‐assisted green synthesis, hybrid Chi‐Fe₃ O₄ nanocomposites, staphylococcus aureus, staphylococcus marcescens, bacterial pathogens, ultraviolet–visible spectrum, spherical‐shaped particles, particle size, transmission electron microscopy, FESEM, field emission scanning electron microscopy, X‐ray diffraction, spinel structure, polycrystalline structure, energy dispersive X‐ray microanalysis, Fourier transform infrared spectroscopic analysis, deformation, bacterial cell walls, Fe₃ O₄      

Prediction of tribological behaviour of rice husk ash reinforced aluminum alloy matrix composites using artificial neural network

Artificial Neural Network (ANN) model was developed to predict the wear rate and coefficient of friction for the Rice Husk Ash (RHA) reinforced aluminum alloy composite. The composite was fabricated using the stir cast route and their tribological behavior was tested using Pin-on-Disc wear tester. The experiments were conducted based on Orthogonal array (L₂₇) generated through the Taguchi Technique and their results were used to train the ANN model. The input parameters assigned to develop an ANN model are applied load, sliding speed, RHA particle size and weight percentage of RHA reinforcement. A four layer perception network having 4-7-8-2 architecture was found to be the optimum network. Finally, confirmation test was done to verify the predictive model with the experimental results and also the wear surface morphology of the wear pin was analyzed using the scanning electron microscope.