Impact of ultrasonic assisted triangular lattice like arranged dispersion of nanoparticles on physical and mechanical properties of epoxy-TiO2 nanocomposites.

Emerging ex-situ technique, ultrasonic dual mixing (UDM) offers unique and hitherto unapproachable opportunities to alter the physical and mechanical properties of polymer nanocomposites. In this study, triangular lattice-like arranged dispersion of TiO2 nanoparticles (average size ∼ 48 nm) in the epoxy polymer has been attained via concurrent use of a probe ultra-sonicator and 4 blades pitched impeller which collectively named as UDM technique. The UDM processing of neat epoxy reveals the generation of triangular lattice-like arranged nanocavities with nanoscale inter-cavity spacing. The UDM processing of epoxy-TiO2 nanocomposites reveals two unique features such as partial and complete entrapping of the nanoparticles by the nanocavities leading the arranged dispersion of particles in the epoxy matrix. Pristine TiO2 nanoparticles were dispersed in the epoxy polymer at loading fractions of up to 20% by weight. The results display that the arranged dispersion of nanoparticles is very effective at enhancing the glass transition temperature (Tg) and tensile properties of the epoxy at loading fractions of 10 wt%. We quantify a direct relationship among three important parameters such as nanoparticle content, cluster size, and inter-particle spacing. Our results offer a novel understanding of these parameters on the Tg and tensile properties of the epoxy nanocomposites. The tensile fracture surfaces revealed several toughening mechanisms such as particle pull-out, plastic void growth, crack deflection, crack bridging and plastic deformation. We show that a strong nanoparticle-matrix interface led to the enhanced mechanical properties due to leading toughening mechanisms such as crack deflection, plastic deformation and particle pull-out. We showed that the UDM has an inordinate prospective to alter the dispersion state of nanoparticles in viscous polymer matrices.

UDM enhanced physical and mechanical properties through the formation of nanocavities in an epoxy matrix.

The matrix modification of relatively low viscous epoxy based polymer treated under ultrasonic mixing (UM) and ultrasonic mixing with simultaneous stirring by a rotating impeller, referred to as ultrasonic dual mixing (UDM), and the effect of processing techniques has been investigated in terms of the formation of nanocavities in the epoxy matrix. Nanocavities of size 42±8nm have been formed uniformly in the epoxy matrix by UDM. The effect of a change in matrix morphology on the viscoelastic, tensile and thermal properties of the cured epoxy resin has been studied. The UDM processed cured epoxy matrix showed 18.26% and 88.34% improvement in tensile strength and toughness as compared to unprocessed epoxy. Thermal gravimetric analysis (TGA) of UDM processed epoxy showed significant enhancement in the thermal stability of the epoxy matrix.

Facile fabrication of epoxy-TiO2 nanocomposites: A critical analysis of TiO2 impact on mechanical properties and toughening mechanisms.

Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO2) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (Tg) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation.

MWCNT/TiO2 hybrid nano filler toward high-performance epoxy composite.

In this work, multi-walled carbon nanotubes (MWCNTs) are decorated by TiO2 nanoparticles and formed a new hybrid structure of filler (MWCNT/TiO2 hybrid filler). The MWCNT/TiO2 hybrid filler is reinforced in epoxy matrix and studied the mechanical and anti-corrosion properties of epoxy. The morphology of newly formed MWCNT/TiO2 hybrid nano filler has been studied using transmission electron microscopy (TEM). Field Emission Scanning Electron Microscope (FESEM) images of tensile fracture surface confirmed the superior dispersion of MWCNT/TiO2 in the epoxy matrix. The resultant MWCNT/TiO2 hybrid-epoxy nanocomposite exhibits superior anti-corrosion and mechanical performance than the nanocomposite produced by loading of only MWCNTs or TiO2 nanoparticles as well as neat epoxy. For example, tensile strength and storage modulus of epoxy increased by 61% and 43% respectively on loading of MWCNT/TiO2 hybrid nano filler. Furthermore, the coating of MWCNT/TiO2 hybrid-epoxy nanocomposite on mild steel reduces the corrosion rate upto 0.87×10-3MPY from 16.81MPY.

Healthcare worker and family caregiver hand hygiene in Bangladeshi healthcare facilities: results from the Bangladesh National Hygiene Baseline Survey.

BACKGROUND: Healthcare facility hand hygiene impacts patient care, healthcare worker safety, and infection control, but low-income countries have few data to guide interventions. AIM: To conduct a nationally representative survey of hand hygiene infrastructure and behaviour in Bangladeshi healthcare facilities to establish baseline data to aid policy. METHODS: The 2013 Bangladesh National Hygiene Baseline Survey examined water, sanitation, and hand hygiene across households, schools, restaurants and food vendors, traditional birth attendants, and healthcare facilities. We used probability proportional to size sampling to select 100 rural and urban population clusters, and then surveyed hand hygiene infrastructure in 875 inpatient healthcare facilities, observing behaviour in 100 facilities. FINDINGS: More than 96% of facilities had 'improved' water sources, but environmental contamination occurred frequently around water sources. Soap was available at 78-92% of handwashing locations for doctors and nurses, but just 4-30% for patients and family. Only 2% of 4676 hand hygiene opportunities resulted in recommended actions: using alcohol sanitizer or washing both hands with soap, then drying by air or clean cloth. Healthcare workers performed recommended hand hygiene in 9% of 919 opportunities: more after patient contact (26%) than before (11%). Family caregivers frequently washed hands with only water (48% of 2751 opportunities), but with little soap (3%). CONCLUSION: Healthcare workers had more access to hand hygiene materials and performed better hand hygiene than family, but still had low adherence. Increasing hand hygiene materials and behaviour could improve infection control in Bangladeshi healthcare facilities.

A49T, R227Q and TA repeat polymorphism of steroid 5 alpha-reductase type II gene and Hypospadias risk in North Indian children.

BACKGROUND/AIMS: Hypospadias is a common congenital error of genital development, the frequency of which is increasing. As androgens have a significant role in the development of the male urethra, we sought to investigate the association between functional polymorphisms of SRD5A2 gene in relation to hypospadias. METHODS: We examined DNA samples of 96 cases and 105 controls for SRD5A2-A49T, R227Q and TA repeat gene polymorphisms. RESULT: Absence of 49T locus and 227Q locus was observed in the present study. At the (TA) n repeat site, TA (0) allele was observed to be the most common allele in both cases (91.7%) and controls (90%). TA (9/9) genotype exhibited an odds ratio of 3.03 (95% C.I. = 0.18-50.14, p = 0) with respect to only middle phenotypes. Analysis of the demographic data depicted the agricultural background aspect of the parents of the cases. 72.27% of the cases (affected with Hypospadias) have parents having agriculture as a primary occupation. CONCLUSION: As longer TA repeats are associated with lower enzymatic activity and lower DHT levels as reported among Caucasians, this polymorphism may have an effect (rather small) in predisposing the population of the present study to the risk of Hypospadias of lesser severity. Due to small sample size, the 3.03 O.R. is not significant and a larger sample is needed to validate the results. Large scale screening of Hypospadias and other 46 X,Y disorders of sexual development is needed especially in India, where the majority of the population is from agricultural background. The results of the present study are likely to assist the health planners to initiate screening of Hypospadias among the farmer community to combat the risk of Hypospadias.

Brownian transport in corrugated channels with inertia.

Transport of suspended Brownian particles dc driven along corrugated narrow channels is numerically investigated in the regime of finite damping. We show that inertial corrections cannot be neglected as long as the width of the channel bottlenecks is smaller than an appropriate particle diffusion length, which depends on the the channel corrugation and the drive intensity. With such a diffusion length being inversely proportional to the damping constant, transport through sufficiently narrow obstructions turns out to be always sensitive to the viscosity of the suspension fluid. The inertia corrections to the transport quantifiers, mobility, and diffusivity markedly differ for smoothly and sharply corrugated channels.

Driven Brownian transport through arrays of symmetric obstacles.

We numerically investigate the transport of a suspended overdamped Brownian particle which is driven through a two-dimensional rectangular array of circular obstacles with finite radius. Two limiting cases are considered in detail, namely, when the constant drive is parallel to the principal or the diagonal array axes. This corresponds to studying the Brownian transport in periodic channels with reflecting walls of different topologies. The mobility and diffusivity of the transported particles in such channels are determined as functions of the drive and the array geometric parameters. Prominent transport features, like negative differential mobilities, excess diffusion peaks, and unconventional asymptotic behaviors, are explained in terms of two distinct lengths, the size of single obstacles (trapping length), and the lattice constant of the array (local correlation length). Local correlation effects are further analyzed by continuously rotating the drive between the two limiting orientations.

Batch biodegradation of para-nitrophenol using Arthrobacter chlorophenolicus A6.

The present study reports the kinetics of p-nitrophenol (PNP) biodegradation by Arthrobacter chlorophenolicus A6 in batch shake flasks for initial PNP concentrations in the range of 25-225 mg l(-1). Results of batch growth kinetics of A. chlorophenolicus A6 at various initial PNP concentrations revealed that the culture followed substrate inhibition kinetics with estimated decay coefficient value of 0.0132 h(-1). Biokinetic constants involved in the process were estimated by fitting the experimental data to several substrate inhibition kinetics models available from the literature. Among the models tested, Webb model fitted the experimental data best with the least root mean square error value, and the estimated model constants values were µ = 0.161 h(-1), K (i) = 128 mg l(-1), K (s) = 60.15 mg l(-1), and K = 100 mg l(-1). In addition, observed and theoretical yield coefficients, maintenance energy, and specific growth rate of the culture at various initial PNP concentrations were also investigated in the study.

Hypospadias risk and polymorphism in SRD5A2 and CYP17 genes: case-control study among Indian children.

PURPOSE: Hypospadias is a common congenital error of genital development, the frequency of which is increasing. As androgens have a significant role in the development of the male urethra, we sought to investigate the association between 2 functional polymorphisms, CYP17-A1/A2 and SRD5A2-V89L, which are involved in the biosynthesis of testosterone and dihydrotestosterone, respectively, in relation to hypospadias. MATERIALS AND METHODS: We examined DNA samples of 80 cases and 100 controls for SRD5A2-V89L and CYP17-A1/A2 gene polymorphisms. Information pertaining to family history, preoperative position of the urethral meatus and parental occupations along with maternal reproductive profile were collected for cases and controls. RESULTS: Genotyping of 80 cases and 100 controls revealed a significant association between V89L polymorphism and hypospadias (OR 2.4, 95% CI 1.2-4.6, p <0.05). When analyzing the risk of hypospadias based on grade, genotypic distribution of SRD5A2-LL genotype differed significantly between severe forms and controls, with an odds ratio of 3.6 (95% CI 1.2-10.0, p = 0.02). Of affected children 71.25% had parents from a rural background, with agriculture as the primary occupation. A statistically significant association was observed for the LL genotype (OR 4.6, 95% CI 1.7-12.29, p <0.05) between children with parents having an agricultural background (likely exposed to pesticides) and controls with no such exposure. CYP17-A1/A2 genotypes did not show any significant results. CONCLUSIONS: V89L polymorphism of the SRD5A2 gene is a strong determinant of hypospadias risk among children of Indian origin. However, our results suggest that the presence of leucine allele, especially among agriculturalists, may increase the propensity of having a child with hypospadias.

Communication: Driven Brownian transport in eccentric septate channels.

In eccentric septate channels the pores connecting adjacent compartments are shifted off-axis, either periodically or randomly, so that straight trajectories parallel to the axis are not allowed. Driven transport of a Brownian particle in such a channel is characterized by a strong suppression of the current and its dispersion. For large driving forces, both quantities approach an asymptotic value, which can be analytically approximated in terms of the stationary distribution of the particle exit times out of a single channel compartment.

Perchlorate degradation using an indigenous microbial consortium predominantly Burkholderia sp.

An acclimatized mixed microbial consortium, predominantly Burkholderia sp., was isolated from an activated sludge and investigated for its potential to degrade perchlorate in batch shake flasks. The 16S rDNA analysis of the predominant strain in the mixed culture showed the closest homology (98%) with Burkholderia sp. ATSB16. For the first time mixed culture with predominantly Burkholderia sp., has been reported to be involved in perchlorate degradation. The substrate perchlorate was completely utilized within 10 days even at a high concentration of 1000 mg L(-1) utilizing succinate as the sole carbon-source. Compared to other carbon-sources tested in this study, succinate proved to be better for perchlorate degradation by the mixed consortium. The optimum conditions for perchlorate degradation by the enriched mixed culture were found to be 30 °C and pH 7.0. The effect of co-pollutants on perchlorate removal by the mixed culture was also investigated at a mixed perchlorate concentration of 500 mg L(-1). Results showed that the degradation of perchlorate was affected to different extent due to the presence of an equal concentration (500 mg L(-1)of each) of co-pollutants such as nitrate, nitrite, chlorate and phosphate.

Biodegradation of 4-chlorophenol by Arthrobacter chlorophenolicus A6: effect of culture conditions and degradation kinetics.

Among known microbial species, Arthrobacter chlorophenolicus A6 has shown very good potential to treat phenolic wastewaters. In this study, the levels of various culture conditions, namely initial pH, agitation (rpm), temperature (°C), and inoculum age (h) were optimized to enhance 4-chlorophenol (4-CP) biodegradation and the culture specific growth rate. For optimization, central composite design of experiments followed by response surface methodology (RSM) was applied. Results showed that among the four independent variables, i.e., pH, agitation (rpm), temperature (°C), and inoculum age (h) investigated in this study, interaction effect between agitation and inoculum age as well as that between agitation and temperature were significant on both 4-CP biodegradation efficiency and culture specific growth rate. Also, at the RSM optimized settings of 7.5 pH, 207 rpm, 29.6°C and 39.5 h inoculum age, 100% biodegradation of 4-CP at a high initial concentration of 300 mg l(-1) was achieved within a short span of 18.5 h of culture. The enhancement in the 4-CP biodegradation efficiency was found to be 23% higher than that obtained at the unoptimized settings of the culture conditions. Results of batch growth kinetics of A. chlorophenolicus A6 for various 4-CP initial concentrations revealed that the culture followed substrate inhibition kinetics. Biokinetic constants involved in the process were estimated by fitting the experimental data to several models available from the literature.

SRD5A2 gene mutations--a population-based review.

Knowledge of steroid 5 alpha-reductase type 2 (SRD5A2) gene mutations is expanding, and its role has been implicated in various disease susceptibilities concerning reproductive health. Extensive research has revealed the tendency for specific SRD5A2 gene mutations to be passed along certain racial, ethnic and geographically isolated groups, which suggests population specificity of these mutations. The review provides evidence of variation in the mutational spectrum of the SRD5A2 gene leading to population-specific high prevalence of characteristic disease or phenotypic expression.

Reducing use of injections through interactional group discussions: a randomized controlled trial.

OBJECTIVE: To determine whether interactional group discussions could reduce prescriptions of injections by physicians. STUDY DESIGN: Randomized controlled trial. SETTING: Rural public health care facilities, North 24 Parganas district, West Bengal, India. SUBJECTS: 72 medical officers, 36 each in intervention and control groups. INTERVENTION: Interactional group discussions. OUTCOME MEASURE: Proportion of prescriptions including at least one injection. RESULTS: In the intervention group, 249 of 1,080 prescriptions (23%) included at least one injection compared with 79 of 1,080 prescriptions (7%) before and after the intervention, respectively. (RR: 0.32, 95% CI: 0.25-0.40). In the control group, 231 of 1,080 prescriptions (21%) included at least one injection before the intervention vs 178 of 1,080 prescriptions (16%) after the intervention (RR 0.77, 95% CI: 0.65-0.92). CONCLUSION: Interactional group discussions reduce prescription of injections.

Antioxidant potential of C-phycocyanin isolated from cyanobacterial species Lyngbya, Phormidium and Spirulina spp.

The antioxidant activity of C-Phycocyanin (C-PC) isolated from three cyanobacterial species Lyngbya (marine), Phormidium (marine) and Spirulina (fresh water) was studied in vitro. The results demonstrate that C-PCs from Lyngbya, Phormidium and Spirulina spp. are able to scavenge peroxyl radicals (determined by crocin bleaching assay) with relative rate constant ratio of 3.13, 1.89 and 1.8, respectively. C-PCs also scavenge hydroxyl radicals (determined by deoxyribose degradation assay) with second order rate constant values of 7.87 x 10(10), 9.58 x 10(10) and 6.42 x 10(10), respectively. Interestingly, Lyngbya C-PC is found to be an effective inhibitor of peroxyl radicals (IC50 6.63 microM), as compared to Spirulina (IC50 12.15 microM) and Phormidium C-PC (IC50 12.74 microM) and is close to uric acid (IC50 2.15 microM). Further, the studies suggest that the covalently-linked tetrapyrrole chromophore phycocyanobilin is involved in the radical scavenging activity of C-PC. The electron spin resonance (ESR) spectra of C-PCs indicate the presence of free radical active sites, which may play an important role in its radical scavenging property. This is the first report on the ESR activity of native C-PCs without perturbations that can cause radical formation.

Microemulsions: a potential drug delivery system.

Microemulsions are clear, transparent, thermodynamically stable dispersions of oil and water, stabilised by an interfacial film of surfactant frequently in combination with a co-surfactant. Recently, there has been a considerable interest for the microemulsion formulation, for the delivery of hydrophilic as well as lipophilic drug as drug carriers because of its improved drug solubilisation capacity, long shelf life, easy of preparation and improvement of bioavailability. In this present review, we discuss about the various advantages of microemulsion in pharmaceuticals, along with its composition variables, physicochemical characterisation etc. The potential use of microemulsion for therapeutic application is also discussed.

Effect of inorganic fertilizer and farmyard manure on soil physical properties, root distribution, and water-use efficiency of soybean in Vertisols of central India.

A field experiment was conducted on a Vertisol for three consecutive years (1998-2000) to study the effects of combined use of inorganic fertilizer (NPK) and organic manure (farmyard manure) on soil physical properties, water-use efficiency, root growth and yield of soybean [Glycine max (L.) Merr.] in a soybean-mustard cropping system. Application of 10 Mg farmyard manure and recommended NPK (NPK+FYM) to soybean for three consecutive years improved the organic carbon content of the surface (0-15 cm) soil from an initial value of 4.4 g kg(-1) to 6.2 g kg(-1) and also increased seed yield and water-use efficiency by 103% and 76%, respectively, over the control. The surface (0-15 cm) soil of the plots receiving both farmyard manure and recommended NPK had larger mean weight diameter (0.50 mm) and a higher percentage of water stable aggregates (55%) than both the inorganically fertilized (NPK) (0.44 mm and 49%) and unfertilized control plots (0.41 mm and 45.4%). The saturated hydraulic conductivity (13.32 x 10(-6) m s(-1)) of the NPK+FYM treatment of the 0-7.5 cm depth was also significantly greater than that of the NPK (10.53 x 10(-6) m s(-1)) and control (8.61 x 10(-6) m s(-1)) treatments. The lowest bulk density (1.18 Mg m(-3)) in the 0-7.5 cm layer was recorded in NPK+FYM whereas it was highest in the control plots (1.30 Mg m(-3)). However, at sub-surface (22.5-30 cm) layer, fertilizer and manure application had little effect on bulk density and saturated hydraulic conductivity. Root length density (RLD) up to the 30 cm depth was highest in the NPK+FYM plots and it was 31.9% and 70.5% more than NPK and control plots. The RLD showed a significant and negative correlation (r=-0.88( * *)) with the penetration resistance.

Galvanic deposition of nanocrystalline ZnO thin films from a ZnO-Zn(OH)(2) mixed phase precursor on p-Si substrate.

A galvanic technique for the deposition of ZnO thin films is reported. The depositions were carried out on p-type single-crystal silicon substrates at room temperature, from a solution of ZnSO(4), where the Zn rod acted as a sacrificing anode and p-Si was the cathode. The deposition of ZnO by this method is pH sensitive, and a pH between 4 and 5 is found to be optimum for film deposition. This deposition technique is simple, inexpensive and can be carried out at room temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies revealed the nanocrystalline structure of the films. The resistivity of the annealed ZnO films was determined by the Van der Pauw measurement technique.

Protection of adrenal and male gonadal functions by androgen in lead-treated rats.

The potential health hazard of the large amounts of Lead that occurs in canned baby food, domestic water from lead-lined tanks and, in printing and petroleum industries. Lead acetate administration at a does of 8 mg/kg body weight for 21 days resulted a significant increase in adrenal steroidogenic enzyme (Delta5-3beta- HSD) and serum levels of corticosterone, while serum levels of testosterone, FSH, LH and testicular spermatogenesis were decreased in albino rats. But lead-treated rats received exogenous testosterone for the last 14 days of lead treatment, showed prevention of adrenocortical hyperactivity by decreasing adrenal Delta5-3beta-HSD activity and serum level of corticosterone. Testosterone administration also increased serum level of testosterone, FSH and LH along with spermatogenesis. The results suggest that testosterone supplementation in lead-treated rats protects adrenocortical activity and testicular spermatogenesis.