Ultrastructural analysis of cell wall of drug resistant and sensitive Mycobacterium tuberculosis isolated from cerebrospinal fluid by transmission electron microscope

Drug‐resistant tuberculosis is being increasingly recognized and is one among the leading cause of death worldwide. Remarkable impermeability of cell wall to antituberculous drugs protects the mycobacteria from drug action. The present study analyzed the cell wall thickness among first‐line drug resistant and sensitive Mycobacterium tuberculosis (Mtb) isolated from cerebrospinal fluid by transmission electron microscopy (TEM). The average thickness of the cell wall of sensitive isolates was 13.60 ± 0.98 nm. The maximum difference (26.48%) in the cell wall thickness was seen among multi‐drug resistant (18.50 ± 1.71 nm) isolates and the least difference (4.14%) was shown by streptomycin‐resistant (14.18 ± 1.38 nm) isolates. The ultrastructural study showed evident differences in the cell wall thickness among sensitive and resistant isolates. Preliminary TEM examination of cells indicates that morphological changes occur in the cell wall which might be attributed to the drug resistance. The thickened wall of Mtb appears to help the bacilli to overcome the action of antituberculous drugs.     

Poly(4‐vinyl pyridine)‐grafted graphene oxide for drug delivery and antimicrobial applications

Graphene oxide (GO) was covalently functionalized with poly(4‐vinyl pyridine) (P4VP) by atom transfer radical polymerization for drug delivery and antimicrobial applications. The physiochemical properties, chemical structure, composition and morphology of the P4VP‐functionalized GO (GO‐P4VP) were studied. Simple physisorption of a cancer drug, camptothecin (CPT), via π ? π stacking and/or hydrophobic interactions on the GO‐P4VP was tested for drug loading and its release by altering the pH. The GO‐P4VP has low cytotoxicity, and the CPT‐loaded GO‐P4VP exhibited a high potency for killing cancer cells in vitro. Prominent antimicrobial properties against Escherichia coli and Staphylococcus aureus were also observed. Thus, the GO‐P4VP can be utilized as a drug delivery vector with high biocompatibility, solubility and stability in physiological solutions, a suitable payload capacity and excellent bacterial toxicity. Owing to its small size, low cost, large specific area, ready scalability and useful non‐covalent interactions, GO‐P4VP is a novel material for biomedical, industrial and environmental applications. © 2015 Society of Chemical Industry     

Learning automata–based multilevel medium access control in cyber physical system–based smart wireless networks

The performance of cyber physical system–based smart wireless networks depends on effective channel access by reducing the blocking, the dropping probability, and collisions. The aim of this proposed algorithm is to reduce the collisions in cyber physical system–based smart wireless networks. In this paper, multilevel medium access control in cyber physical system–based smart wireless networks is proposed. The optimal number of levels of gateways is determined using the concept of learning automata. Priority and time limit are assigned to every packet that is being transmitted. The proposed algorithm is evaluated and compared with two‐level medium access control in cyber physical system–based smart wireless networks, which is referred as priority with counter modified backoff (PCMB). The parameters used for evaluating the performance are throughput, delay, % of collisions, and number of packets dropped. The results project that the proposed algorithm accomplishes improved performance than PCMB.     

Study of the Choice of Excitation Frequency for Sub Surface Defect Detection in Electrically Thick Conducting Specimen Using Eddy Current Testing

Understanding the scope and limitations of non-destructive testing procedure is essential for selecting the appropriate test parameters for material inspection. This paper presents the scope of material (\( \delta_{s} \)) and probe dependent (\( \delta_{t} \)) penetration depths for determining the optimal test frequency (\( f_{opt} ) \) for detection of sub surface defects in electrically thick conducting specimens. Numerical modelling is carried out for a pancake coil above an electrically thick aluminium plate, \( t/\delta_{t} \)?>?1, to study the influence of the EC probe and defect location (\( t_{df} \)) on the test frequency for near and deep sub surface defects. The study concludes that the optimal test frequency, \( f_{opt} \) for detection of deep sub surface defects (\( t_{df} /t \approx 1 \)) is determined by the probe dependent skin depth, \( \delta_{t} \), and the plate thickness is related to \( f_{opt} \) by, \( t \propto 1/\sqrt {f_{opt} } \). The numerical observations were experimentally validated for machined sub surface notches on a 10 mm thick (\( t \)) aluminium plate.     

AGGLO-Hi clustering algorithm for gene expression micro array data using proximity measures

Gene selection is imperative to clustering in light of gene articulation information, as a result of high Clustering quality. Clustering gene articulation information is a vital research subject in bioinformatics on the grounds that knowing which genes act correspondingly can prompt the disclosure of vital natural data. Many clustering systems have been proposed to the examination of gene articulation information got from microarray innovation. Clustering is one of the major procedures of investigating gene articulation information, fundamentally by contrasting gene articulation profiles or test articulation profiles. The Proposed strategy is an Agglo-Hi clustering algorithm which is accounted for the fuse of vicinity similarity estimates like Euclidean Distance, Manhattan Distance Chebyshev Distance, and Cosine Similarity for their execution. The technique is quality articulation information in microarray which is extricated and quality can be chosen from the preprocessed information, at that point the Agglo-Hi Clustering algorithm is utilized for quality information. The grouped information get approved utilizing legitimacy file and the outcome is gotten in light of nearness measures. To refine quality articulation information onto enhanced bunch quality by accelerating Unsupervised Learning stage and the execution of Agglo-Hi algorithm figures the Clustering quality, exactness and time unpredictability.

     

DNA sensing by silicon nanowire: charge layer distance dependence

To provide a comprehensive understanding of the field effect in silicon nanowire (SiNW) sensors, we take a systematic approach to fine tune the distance of a charge layer by controlling the hybridization sites of DNA to the SiNW preimmobilized with peptide nucleic acid (PNA) capture probes. Six target DNAs of the same length, but differentiated successively by three bases in the complementary segment, are hybridized to the PNA. Fluorescent images show that the hybridization occurs exclusively on the SiNW surface between the target DNAs and the PNA. However, the field-effect response of the SiNW sensor decreases as the DNA (charge layer) moves away from the SiNW surface. Theoretical analysis shows that the field effect of the SiNW sensor relies primarily on the location of the charge layer. A maximum of 102% change in resistance is estimated based on the shortest distance of the DNA charge layer (4.7 A) to the SiNW surface.     

Amino acid-assisted synthesis of strontium hydroxyapatite bone cement by a soft solution freezing method

Among many cations that can substitute for calcium in the structure of hydroxyapatite, strontium provokes an increasing interest because of its beneficial effect on bone formation and prevention of bone resorption. Strontium-incorporated calcium phosphates show potential in biomedical application, particularly the doped strontium may help in new bone formation. We have synthesized strontium hydroxyapatite powders at 2 °C by a soft solution freezing method using glycine as the template. The structural and morphological characterizations were carried out on the as obtained powders using Fourier transform infrared spectroscopy, X-ray diffraction analysis and scanning electron microscopy techniques. Strontium was quantitatively incorporated into hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. The strontium substituted bone cement has potential for use in orthopaedic surgeries. The present study shows that the addition of glycine plays an important role in reducing the particle size of strontium hydroxyapatite which could be used for biomedical applications.     

Identification of growth mechanism of CBD CIAS thin films from SEM analysis

Near stoichiometric and stoichiometric CuIn_(1?x)Al_(x)Se₂ (CIAS) thin films have been prepared by chemical bath deposition (CBD) technique. X-ray diffraction (XRD) and energy dispersive x-ray analysis (EDAX) spectra have been employed to confirm the structure and composition of the prepared films. SEM analysis of near-stoichiometric and stoichiometric CIAS thin films enabled us to estimate the grain size, to identify the growth mechanism and also to visualize the surface morphology. Transmittance spectra have been employed to determine the type of transition and other optical parameters such as absorption coefficient, extinction coefficient, dielectric constant, refractive index, Sellmeier parameters and bandgap which are reported in this paper in detail.