Large area fabrication of vertical silicon nanowire arrays by silver-assisted single-step chemical etching and their formation kinetics.

Vertically aligned silicon nanowire (SiNW) arrays have been fabricated over a large area using a silver-assisted single-step electroless wet chemical etching (EWCE) method, which involves the etching of silicon wafers in aqueous hydrofluoric acid (HF) and silver nitrate (AgNO3) solution. A comprehensive systematic investigation on the influence of different parameters, such as the etching time (up to 15 h), solution temperature (10-80 °C), AgNO3 (5-200 mM) and HF (2-22 M) concentrations, and properties of the multi-crystalline silicon (mc-Si) wafers, is presented to establish a relationship of these parameters with the SiNW morphology. A linear dependence of the NW length on the etch time is obtained even at higher temperature (10-50 °C). The activation energy for the formation of SiNWs on Si(100) has been found to be equal to ∼0.51 eV . It has been shown for the first time that the surface area of the Si wafer exposed to the etching solution is an important parameter in determining the etching kinetics in the single-step process. Our results establish that single-step EWCE offers a wide range of parameters by means of which high quality vertical SiNWs can be produced in a very simple and controlled manner. A mechanism for explaining the influence of various parameters on the evolution of the NW structure is discussed. Furthermore, the SiNW arrays have extremely low reflectance (as low as <3% for Si(100) NWs and <12% for mc-Si NWs) compared to ∼35% for the polished surface in the 350-1000 nm wavelength range. The remarkably low reflection surface of SiNW arrays has great potential for use as an effective light absorber material in novel photovoltaic architectures, and other optoelectronic and photonic devices.

Comparative study of leaching of silver nanoparticles from fabric and effective effluent treatment.

Nano silver (Ag(n)) is employed as an active antimicrobial agent, but the environmental impact of Ag(n) released from commercial products is unknown. The quantity of nanomaterial released from consumer products during use should be determined to assess the environmental risks of advancement of nanotechnology. This work investigated the amount of silver released from three different types of fabric into water during washing. Three different types of fabric were loaded with chemically synthesized Ag nanoparticles and washed repeatedly under simulated washing conditions. Variable leaching rates among fabric types suggest that the manufacturing process may control the release of silver reaching the waste water treatment plants. In an attempt to recover the Ag(n) for reutilization and to save it from polluting water, the effluents from the wash were efficiently treated with bacterial strains. This treatment was based on biosorption and was very efficient for the elimination of silver nanoparticles in the wash water. The process ensured the recovery of the Ag(n) leached into the effluent for reutilization, thus preventing environmental repercussions.

Novel nanostructures and optical properties of silver doped sodium phosphate thin films.

(50-x)Na2O-50P2O5-xAgCl (x = 0 to 15 mol%) glasses in bulk form were synthesized using melt-quenching technique. Thin films of these silver doped sodium phosphate glasses were deposited by thermal evaporation process. The influence of deposition of these glasses in thin film form and subsequent annealing at 600 degrees C on the structure and optical properties such as transmittance, reflectance, refractive index and band gap have been investigated in detail. X-ray diffraction studies of the as-deposited films show the films to be amorphous whereas annealed films show existence of orthorhombic and monoclinic phase of NaPO3 along with crystalline cubic phase of AgCl in doped glasses. Structural investigations of these annealed films show unique morphologies (needle-like and granular) at nano-scale. Both as-fabricated and annealed films are poor reflectors but show high transmittance in the entire spectral region under consideration, which is a direct consequence of particle size effects. Indirect band gap narrowing and variation in refractive index upon annealing is consistent with nanostructural transformations in these samples.

Effect of variable pressure on growth and photoluminescence of ZnO nanostructures.

Thin films constituted of equiaxed and one dimensional nanostructures of ZnO via metal-catalyst-free vapor phase were grown using a simplistic thermal evaporation technique under two different pressure conditions approximately of the order of 10(-1) and 10(-3) torr, respectively. ZnO deposited at low vacuum (approximately 10(-1) torr) exhibited the formation of nanograins of variable size between 60 to 180 nm. In contrast the film grown at high vacuum (approximately 10(-3) torr) resulted the nanowired type morphology with a random networking, generally distributed with equiaxed grains of film microstructure. The diameter of maximum number of these nanowires lies between 45 to 65 nm. The films grown at low vacuum has shown almost equal composition of Zn and O while the film grown at high vacuum has shown lower content of O. The nanowires formed under limited O (high vacuum: approximately 10(-3) torr) signifies the role of O vacancies during growth. It has been postulated that presumably under high vacuum deposition, initially formed ZnO transforms to ZnOx (x < 1) through creation of O vacancies due to limited presence of O. Subsequently ZnOx acts as self-catalyst and heterogeneous nuclei are responsible for the formation of nanowired type morphology. The effect of different microstructures has been correlated and discussed to understand the photoluminescence characteristics obtained on these films.

Impact of Time-Restricted Feeding and Dawn-to-Sunset Fasting on Circadian Rhythm, Obesity, Metabolic Syndrome, and Nonalcoholic Fatty Liver Disease.

Obesity now affects millions of people and places them at risk of developing metabolic syndrome, nonalcoholic fatty liver disease (NAFLD), and even hepatocellular carcinoma. This rapidly emerging epidemic has led to a search for cost-effective methods to prevent the metabolic syndrome and NAFLD as well as the progression of NAFLD to cirrhosis and hepatocellular carcinoma. In murine models, time-restricted feeding resets the hepatic circadian clock and enhances transcription of key metabolic regulators of glucose and lipid homeostasis. Studies of the effect of dawn-to-sunset Ramadan fasting, which is akin to time-restricted feeding model, have also identified significant improvement in body mass index, serum lipid profiles, and oxidative stress parameters. Based on the findings of studies conducted on human subjects, dawn-to-sunset fasting has the potential to be a cost-effective intervention for obesity, metabolic syndrome, and NAFLD.

Chronic exposure to neonicotinoids reduces honey bee health near corn crops.

Experiments linking neonicotinoids and declining bee health have been criticized for not simulating realistic exposure. Here we quantified the duration and magnitude of neonicotinoid exposure in Canada's corn-growing regions and used these data to design realistic experiments to investigate the effect of such insecticides on honey bees. Colonies near corn were naturally exposed to neonicotinoids for up to 4 months-the majority of the honey bee's active season. Realistic experiments showed that neonicotinoids increased worker mortality and were associated with declines in social immunity and increased queenlessness over time. We also discovered that the acute toxicity of neonicotinoids to honey bees doubles in the presence of a commonly encountered fungicide. Our work demonstrates that field-realistic exposure to neonicotinoids can reduce honey bee health in corn-growing regions.

A male-specific quantitative trait locus on 1p21 controlling human stature.

BACKGROUND: Many genome-wide scans aimed at complex traits have been statistically underpowered due to small sample size. Combining data from several genome-wide screens with comparable quantitative phenotype data should improve statistical power for the localisation of genomic regions contributing to these traits. OBJECTIVE: To perform a genome-wide screen for loci affecting adult stature by combined analysis of four previously performed genome-wide scans. METHODS: We developed a web based computer tool, Cartographer, for combining genetic marker maps which positions genetic markers accurately using the July 2003 release of the human genome sequence and the deCODE genetic map. Using Cartographer, we combined the primary genotype data from four genome-wide scans and performed variance components (VC) linkage analyses for human stature on the pooled dataset of 1417 individuals from 277 families and performed VC analyses for males and females separately. RESULTS: We found significant linkage to stature on 1p21 (multipoint LOD score 4.25) and suggestive linkages on 9p24 and 18q21 (multipoint LOD scores 2.57 and 2.39, respectively) in males-only analyses. We also found suggestive linkage to 4q35 and 22q13 (multipoint LOD scores 2.18 and 2.85, respectively) when we analysed both females and males and to 13q12 (multipoint LOD score 2.66) in females-only analyses. CONCLUSIONS: We strengthened the evidence for linkage to previously reported quantitative trait loci (QTL) for stature and also found significant evidence of a novel male-specific QTL on 1p21. Further investigation of several interesting candidate genes in this region will help towards characterisation of this first sex-specific locus affecting human stature.

Evaluation of Early versus Delayed Laparoscopic Cholecystectomy in Acute Cholecystitis.

Background. The role of early laparoscopic cholecystectomy for acute cholecystitis with cholelithiasis is not yet established. The aim of our prospective randomized study was to evaluate the safety and feasibility of early LC for acute cholecystitis and to compare the results with delayed LC. Methods. Between March 2007 to December 2008, 50 patients with diagnosis of acute cholecystitis were assigned randomly to early group, n = 25 (LC within 24 hrs of admission), and delayed group, n = 25 (initial conservative treatment followed by delayed LC, 6-8 weeks later). Results. We found in our study that the conversion rate in early LC and delayed LC was 16% and 8%, respectively, Operation time for early LC was 69.4 min versus 66.4 min for delayed LC, postoperative complications for early LC were 24% versus 8% for delayed LC, and blood loss was 159.6 mL early group versus 146.8 mL for delayed group. However early LC had significantly shorter hospital stay (4.1 days versus 8.6 days). Conclusions. Early LC for acute cholecystitis with cholelithiasis is safe and feasible, offering the additional benefit of shorter hospital stay. It should be offered to the patients with acute cholecystitis, provided that the surgery is performed within 96 hrs of acute symptoms by an experienced surgeon.

Role of aluminium in sporadic motor neuron disease.

In an attempt to ascertain the role of aluminium in sporadic motor neuron disease (MND), trace metals were estimated in blood, plasma and cerebrospinal fluid (CSF) of 38 patients of sporadic MND and 30 controls by direct current plasma emission spectrophotometry. CSF aluminium levels (20.76 +/- 4.38 micrograms/dl) were significantly higher (P less than 0.05) in those patients of MND who presented as progressive bulbar palsy (PBP) as compared to the other subtypes of MND (amyotrophic lateral sclerosis = 7.71 +/- 2.01 micrograms/dl; progressive muscular atrophy = 10.01 +/- 2.41 micrograms/dl) and controls (11.63 +/- 2.82 micrograms/dl). Aluminium may be important in the etiopathogenesis of a subgroup of sporadic MND.

Biliary obstruction due to ruptured hydatid cyst.

Intrabiliary rupture of a hydatid cyst of the liver is a rare complication. It can give rise to jaundice due to cholangitis, and common bile duct obstruction caused by hydatid membranes and daughter cysts. A case of intrabiliary ruptured hydatid cyst presenting as abscess of the liver is reported with a brief review of relevant literature.

Q-T interval changes in acute transmural myocardial infarction.

The serial Q-T interval changes were studied in 29 survivors of acute transmural anteroseptal (11 patients), extensive anterior (10 patients), and inferior (8 patients) myocardial infarctions admitted 4 to 48 hours after the acute episode. Q-T prolongation evidenced by abnormal Q-T ratio was a constant and almost universal feature detected in 28 (97.06%) patients. The maximum Q-T prolongation was observed on an average about 36 hours after the onset of acute episode. Patients with anterior myocardial infarction had significantly higher Q-T ratios than inferior myocardial infarction group. There was a rapid decline towards normal in anteroseptal and inferior myocardial infarction groups in which it settled during initial six days, whereas, in extensive anterior myocardial infarction group, it took a longer time beyond six days to settle. The normalization of Q-T interval did not correspond to settling down of the elevated ST segment. Patients having ventricular tachyarrhythmias (VT and frequent VPBS) (14) had significantly higher Q-T ratios than those without arrhythmias. Further, the Q-T ratio was significantly higher in patients with VT (4) than in those with frequent VPBs (10). Alterations in Q-T ratio were not related to severity or extent of infarction and occurrence of heart failure. It is concluded that prolongation of electrical systole (Q-T interval) is a constant phenomenon after acute transmural myocardial infarction, magnitude and time course of its alterations being related to location of infarct and its electrical complications. It does not seem to have any correlation with mechanical complications of infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of pulmonary perfusion in lung regions showing isolated xenon-133 ventilation washout defects.

Xenon-133 washout phase imaging is often used to help determine whether the etiology of a perfusion defect is embolic or due to pulmonary parenchymal pathology, such as chronic obstructive pulmonary disease. This study was designed to evaluate the pulmonary blood flow patterns associated with isolated defects on xenon washout images. Scintigraphic lung studies were reviewed until 100 cases with abnormal ventilation results were obtained. Ventilation abnormalities were compared with the corresponding perfusion scan results at the same anatomic site. Of the 208 individual lung regions with xenon abnormalities, 111 showed isolated washout defects (that is, with normal washin). Ninety-four of these 111 sites showed either normal perfusion or a small, nonsegmental corresponding perfusion defect. Three segmental perfusion defects were noted in association with isolated xenon retention. In each of these cases, however, the patient was felt actually to have pulmonary embolism. Thus, it is recommended that, for interpretation of scintigraphic images in the assessment of pulmonary embolism, lung pathology associated with isolated xenon retention not be considered a potential cause for large or segmental perfusion defects.

Amebic peritonitis.

Fifteen cases with generalized amebic peritonitis have been described. Early surgical intervention combined with intensive resuscitation and specific chemotherapy has given good results. Mortality associated with colonic perforation may be reduced by performing staged procedures. Chances of survival may be improved through early diagnosis by suspecting an amebic cause in cases of generalized peritonitis in endemic areas.

Plasma lipoproteins in cortical and lacunar infarction.

Plasma lipoproteins in 30 patients of cortical infarction and 20 patients of lacunar infarction were estimated to study the relation of plasma lipids to the risk for ischaemic stroke by comparing clinical and biochemical characteristics of survivors. No significant differences were observed in the concentrations of total cholesterol, triglycerides, low density lipoproteins, very low density lipoproteins in both the groups. However patients with lacunar infarction had higher concentrations of high density lipoproteins as compared to patients with cortical infarction. These data suggest that previously demonstrated differences in HDL concentration between patients with ischaemic stroke and control subjects without stroke may be true for patients with cortical infarction but not for patients of lacunar infarction.

Clinical profile of stroke in relation to glycaemic status of patients.

Present study was undertaken in fifty consecutive patients of acute stroke to assess the role of glycemic status on clinical profile of stroke. Majority of patients (76%) were in age group of 41-70 years. The patients were classified into four groups: euglycemics (33), known diabetics (8), newly diagnosed diabetics (6) and stress hyperglycemics (3). Diabetics as well as stress hyperglycemics had higher prevalence of larger sized severe haemorrhagic stroke with poor outcome and there was positive correlation between them.

Complications of treadmill testing.

Complications occurring in 2,400 treadmill tests are reported, out of which 2107 (87.8%) were on males and 292 (12.2%) on females. The total number of patients with complications was 29 (1.2%) and the types were: acute MI in 2, ventricular tachycardia (sustained) in 3, nonsustained in 7 with ventricular couplets in 3 patients, atrial tachyarrhythmias in four of AVNRT in 2, EAT in 2, SVT with abberancy in 1, SVT (undifferentiated) in 3, bradyarrhythmias in form of sinus bradycardia in 4, hypotension in 4 and AV block in 2. There were no deaths. Only 8 (0.33%) patients required treatment-2 each of acute MI, sustained VT, AVNRT and hypotension, though only 4 of them were hospitalised (2 each of acute MI and VT) and subsequently discharged. Highest incidence of complications was seen in post MI patients (2.01%) followed by those with typical anginal pain (1.9%) and they had more serious problems in form of MI and sustained VT. 55.17% patients with complications were positive for provocative ischaemia as compared to 22.75% positivity in the total. Although 14 (38.2%) patients developed complications at workload of 4-6 METS but 2 achieved load of 10 METS also. Complications were seen mostly during exercise and also during recovery only.

A study of nerve conduction velocity in patients on diphenylhydantoin therapy.

Peripheral nerve conduction studies were performed in 30 epileptics, treated with DPH and results were compared with age and sex matched controls. There was significant reduction in the amplitude of sensory nerve action potential of median (26.65 +/- 14.71 mu v) and superficial radial nerve (25.65 +/- 10.08 mu v) (p < 0.001) in DPH treated group as compared to controls, (median nerve 42.64 +/- 15.93 uv and superficial radial nerve 40.72 +/- 24.74 mu v). The results suggest that DPH causes a subclinical distal axonal neuropathy in therapeutic dosage.

Japanese B encephalitis with neurocysticercosis.

A case of Japanese encephalitis (JE) with multiple calcified lesions suggestive of calcified neurocysticercosis on CT scan of the head is reported. The presence of nonenhancing calcified lesions and rising antibody titres for JE differentiated it from acute encephalitis neurocysticercosis. Post mortem studies indicate that neurocysticercosis predisposes to fatal JE infection. The present report is of an association of the two diseases which did not result in a fatal outcome.

An epidemiological study of obesity in Shimla Town.

A cross sectional study of 888 randomly selected subjects in Shimla town was done to determine prevalence of obesity, its relation to age and physical activity. The prevalence of obesity was 21.5% using cut off levels of BMI 25. The prevalence of obesity rose significantly with age. Obesity was less in those having moderate physical activity as compared to those with low and high activity. Primary prevention is required to tackle this disease risk factor through health education focussing on promotion of moderate regular physical activity.