Study on the Crystal Structure and Microstructure Evolution of Shock-processed Titanium Powder

Titanium powder was rapidly solidified by using shock-wave consolidation technique. The critical parameters were controlled by intrumented detonics and pin-oscillography. The compacted specimens were investigated for crystal structure and microstructural strengthening by using standard diagnostic techniques. The density of the final product was found to be greater than 96% of the theoretical value. X-ray diffraction pattern reveals intact crystalline structure without the presence of any undesired phases. The particle size reduction indicated by XRD was supported by laser diffraction based particle size analyzer. Results from energy dispersive spectroscopy ruled out the possibility of any segregation within the compacts. Scanning electron microscopy showed crack-free, voids-free, melt-free, fracture-less compacts of titanium with a unidirectional dendrite orientation without any grain-growth

Challenges of Second-hand Smoke: Are We Asking the Right Questions?

Second-hand tobacco smoke as defined by WHO is the smoke emitted by a smoker or released from a burnt cigarette or any tobacco product. It is highly prevalent all over the globe but its serious health implications are often neglected by the public and the scientific community alike. Second-hand smoke has everlasting impact on all the body’s major organs, especially among the vulnerable population of children, pregnant ladies, people with chronic diseases and senior citizens. Although India started its war against this menace earlier than other counties, all its efforts remain bootless as its approach and implementation have a wide range of lacunae. This review aims to give a big picture of second-hand smoke, highlighting its pathophysiological changes in the body, socioeconomic impact, various strategies, and the gap that prevents these strategies from finding a favorable result in India. It becomes all the more important to reduce its impact owing to the increase in prevalence among youth reducing their vitality, derailing the society and the nation. It is recommended that the health authorities approach this health problem with utmost seriousness as a laid-back approach could welcome this silent killer’s known and unknown repercussions

Thermally Evaporated Poly(Aniline-co-Fluoroaniline) Films for Ammonia Sensing

Chemically synthesized poly(aniline-co-fluoroaniline) [poly(An-FAn)] powder were deposited on platinum substrates using thermal evaporation technique [poly(An-FAn)/vac]. These films were characterized using spectroscopic and cyclic voltammetry techniques. Electrical conductivity and molecular weight of copolymer have been measured. Results revealed that the structure of poly(An-FAn) is maintained during thermal evaporation. The response of poly(An-FAn)/vac films in terms of change in resistance with different concentration of ammonia shows its utility as a sensor material. The films show good response for ammonia. The sensing of 50 ppm of ammonia was achieved with response and recovery time of 13 and 80 seconds, respectively

Lipase immobilized carbon nanotubes for conversion of Jatropha oil to fatty acid methyl esters

Lipase has been immobilized on multi-walled carbon nanotubes (MWCNTs) through the reaction of the carboxylated nanotubes with the enzyme in the presence of N-hydroxysulfosuccinimide (NHS) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride. Successful immobilization has been verified by infrared spectroscopy and scanning electron microscopy. The synthesized biomaterial has been used for catalyzing the conversion of Jatropha oil to the fatty acid methyl esters (FAME). Progress of the conversion reaction has been monitored with NIR spectroscopy. Gas chromatographic studies have indicated that the use of lipase–MWCNT bioconjuagate leads to almost quantitative conversion of Jatropha oil to the FAME. Around 1 h of the reaction, in the presence of around 15% of catalyst (mass fraction of catalyst on the total mixture), has yielded the desired results. The above used catalyst support has been regenerated 10 times without any adverse effect on the enzyme activity

Bioconjugation of anti estrogen alpha antibody with CdSSe/ZnS quantum dots for molecular sensing of a breast cancer antigen

In this present work, amine functionalized CdSSe/ZnS (core/shell) QDs have been conjugated with an anti-ERα antibody, which is a specific antibody against breast cancer antigen ERα. The bioconjugation reaction has been optimized with respect to the pH, reaction time and ionic strength of the media. Molecular interaction between the QDs conjugated antibodies and a dye (FITC) labeled ERα antigen provided a fluorescence resonance energy transfer (FRET) based pathway for quantitative detection of antigen. Upon excitation with 465 nm light, the PL intensity of FRET donor (QDs) decreases proportionally with increasing antigen concentration. Simultaneously, increase in the PL intensity of the FRET acceptor was observed. FRET immunoassay of ERα is sensitive and a wide linear range of detection (10–300 ng mL−1 ERα) observed. FRET efficiency of ∼70% has been achieved. Estimated limit of detection of ERα is 120 pM

Synthesis of mercaptopropionic acid stabilized CDS quantum dots for bioimaging in breast cancer

Semiconductor inorganic nanocrystals or quantum dots (QDs) are nowadays extensively used for imaging and analysis of biomolecules owing to their superior optical properties over conventional organic fluorophores. They have excellent potential for synthesizing molecular probes against various biological markers such as free antigens, cell surface markers/antigens, bacteria, viruses and tissues. Traditional synthesis protocols of the QDs generally lead to the formation of hydrophobic nanocrystals. For biological applications, post-synthesis modifications need to be introduced to render required hydrophilicity. However, such additional steps make the tiny QDs structures bulky, which is unwanted in subsequent in-vivo executions. The present work reports a simple method for the direct synthesis of hydrophilic carboxyl (–COOH) functionalized CdS QDs using mercaptopropionic acid as a sulfur source and stabilizer. This aqueous synthesis route avoids the requirement of extra surface modification steps. The size and surface morphology of the synthesized CdS QDs were studied by electron microscopy. The average diameter of the QDs has been found to be in the range of 2-3.5nm. Spectral studies confirmed the grafting of –COOH terminal on the synthesized nanocrystals. Band gap energy and the theoretical size of the particles were calculated and found in good agreement with the experimental analysis. Due to the size quantization effect, the estimated band gap energy (2.6eV) of the QDs was on a higher side than that reported (2.4eV) for the bulk material. The synthesized nanocrystals can be further conjugated with bio-molecules for high-throughput drug screening, clinical immunological assays and protein-protein interaction studies

Highly Sensitive Glucose Sensing With Multi-Walled Carbon Nanotubes – Polyaniline Composite

Multi-walled carbon nanotubes (MWCNTs) have been carboxylated and then immobilized with glucose oxidase (GOx) by amine coupling through EDC-NHS chemistry. These functionalized MWCNTs have been introduced into polyaniline matrix by electrochemical method. The different involved steps have been characterized with molecular and electronic spectroscopy. Prepared thin films preserved the enzymatic activity of GOx and their average electrical conductivity was measured as 3.78 × 10−1 S cm−1. Observed response time was 5 s and a linear pattern of current vs. concentration was recorded for 0.5–22 mM glucose

Nanostructured polyaniline films on silicon for sensitive sensing of ammonia

Silicon (Si)–nanopolyaniline (PAni) conducting platform has been electrochemically developed for the sensitive sensing of ammonia. The nano PAni films are formed through the assembly of nano granules of the polymer. The average height of the film is in the range of 50 nm. The electrical conductivity of the Si–PAni is influenced in the presence of ammonia. The response of this conductometric sensor is almost linear within 5–50 ppm of ammonia. The response and the recovery times are observed to be 10 and 60 s, respectively for 10 ppm of ammonia. The response time of the sensor for other concentrations (viz. 20, 30, 40, 50 and 60 ppm ammonia) is also in the range of 10 ± 2 s. However, the recovery of the sensor takes slightly longer time (70 ± 3 s) in case of higher concentrations (≥40 ppm) of ammonia

Bioconjugation of InGaP quantum dots for molecular sensing

Fluorescence-based molecular sensing and cellular imaging are commonly carried out with the application of organic dyes. Quantum dots (QDs) are now recognized as better tools because they are brighter, size tunable, and more photostable than dyes. Most of the proposed QD-based biosensing systems involve elements of known toxicity. The present work reports the functionalization of biocompatible InGaPanS core-shell QDs with anti-bovine serum albumin (anti-BSA) to exploit them as fluorescent probes for antigen detection. Successful bioconjugation was characterized with the absorption and emission spectra showing blue shifts of around 40 and 30 nm, respectively. Gel electrophoresis and particle size distribution studies further confirmed the mass increment of QDs after their functionalization with anti-BSA. Surface plasmon resonance spectrometry has been used to study the affinity of QD-(anti-BSA) probes for bovine serum albumin (BSA). Photoluminescence quenching of the developed probe is observed in the presence of BSA. (C) 2011 Elsevier Inc. All rights reserved