Effect of austempering treatment on microstructure and mechanical properties of high-Si steel

In the present investigation, the influence of austempering treatment on the microstructure and mechanical properties of silicon alloyed cast steel has been evaluated. The experimental results show that an ausferrite structure consisting of bainitic ferrite and retained austenite can be obtained by austempering the silicon alloyed cast steel at different austempering temperature. TEM observation and X-ray analysis confirmed the presence of retained austenite in the microstructure after austempering at 400 °C. The austempered steel has higher strength and ductility compared to as-cast steel. With increasing austempering temperature, the hardness and strength decreased but the percentage of elongation increased. A good combination of strength and ductility has been obtained at an austempering temperature of 400 °C.     

Growth, Optical, Mechanical, Dielectric and Theoretical Studies on Potassium Pentaborate Tetrahydrate (KB_5O_8·4H_2O) Single Crystal by Modified Sankaranarayanan-Ramasamy Method

A nonlinear optical single crystal of potassium pentaborate tetrahydrate (KB5O8·4H2O) has been grown from aqueous solution by using unidirectional crystal growth method of Sankaranarayanan-Ramasamy (SR) with a due modification in the growth assembly. Potassium pentaborate crystal of 60 mm length and 10 mm diameter has been grown along (100) plane with a growth rate of 3 mm per day within a period of 20 days. The grown crystal was subjected to single crystal X-ray diffraction analysis to confirm that the cry...     

Failure analysis of railroad wheels

Failure of three railroad wheels, each belonged to a different train but to the same heat, was analyzed. It was found that the wheels were failed due to improper heat treatment.     

Cenosphere filled aluminum syntactic foam made through stir-casting technique

Cenospheres in the range of 30–50 vol.% were used as space holders for making syntactic aluminum foam having density 1.5–1.9 gm/cc using stir-casting technique. The synthesized syntactic foam (SF) was characterized in terms of microstructures, hardness and compressive deformation behaviour. It was noted that the SF behaves like a high strength aluminium foam under compressive deformation exhibiting flat plateau region in the stress–strain curves. The plateau stress of SF decreases with cenosphere volume fraction vis-à-vis porosity following a power law relationship. But, the densification strain increases linearly with cenosphere volume fraction.     

Experimental determination of thermal conductivity of three nanofluids and development of new correlations

Experimental investigations have been carried out for determining the thermal conductivity of three nanofluids containing aluminum oxide, copper oxide and zinc oxide nanoparticles dispersed in a base fluid of 60:40 (by mass) ethylene glycol and water mixture. Particle volumetric concentration tested was up to 10% and the temperature range of the experiments was from 298 to 363 K. The results show an increase in the thermal conductivity of nanofluids compared to the base fluids with an increasing volumetric concentration of nanoparticles. The thermal conductivity also increases substantially with an increase in temperature. Several existing models for thermal conductivity were compared with the experimental data obtained from these nanofluids, and they do not exhibit good agreement. Therefore, a model was developed, which is a refinement of an existing model, which incorporates the classical Maxwell model and the Brownian motion effect to account for the thermal conductivity of nanofluids as a function of temperature, particle volumetric concentration, the properties of nanoparticles, and the base fluid, which agrees well with the experimental data.     

Isolation and evaluation of a high H2-producing lab isolate from cow dung

Hydrogen producing bacterial strain was isolated from Indian cow dung and identified of the bacterial family Enterobacteriaceae. This lab isolate was differentiated from Citrobacter Y-19 at molecular level by using RAPD, PCR based technique, and OPO-03₄₆₀ and OPO-17₈₀₀ RAPD marker for this specific strain (lab isolate) was identified. Fermentative studies were investigated for important parameters, starting with pH of the culture, temperature, inoculum age and inoculum volume, initial substrate concentration and different substrates. Among different substrates, dextrose and sucrose were the preferred substrates for hydrogen production. The optimal starting pH of the culture was found to be 5.0. The H₂ production increased with increase in temperature up to 30 °C. The maximum value of H₂ production was recorded when inoculum volume was 12.5% of the culture broth and inoculum age was 14 h. Under batch fermentation conditions, the maximum hydrogen production rate and yield were 355.2 ml l⁻¹ h⁻¹ and 2.1 mol/mol glucose (conversion 35%), respectively. These results indicate that this lab isolate is an ideal hydrogen producer.     

Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study

Sorption capacity of oyster mushroom (Pleurotus platypus), button mushroom (Agaricus bisporus) and milky mushroom (Calocybe indica) were evaluated on biosorption of heavy metals, viz. cadmium (II) and lead (II) from aqueous solutions. The optimum sorption conditions were studied for each metal separately. The desired pH of the aqueous solution was found to be 6.0 for the removal of cadmium (II) and 5.0 for removal of lead (II) for all the mushrooms. The percent removal of both the metals was found to increase with the increase in biosorbent dosage and contact time. The fitness of the biosorption data for Langmuir and Freundlich adsorption models was investigated. It was found that biosorption of cadmium (II) and lead (II) ions onto the biomass of the three mushrooms were better suitable to Langmuir than Freundlich adsorption model. P. platypus showed the highest metal uptake potential for cadmium (q_max 34.96 mg/g) whereas A. bisporus exhibited maximum potential for lead (q_max 33.78 mg/g). Milky mushroom showed the lowest metal uptake capacity for both the metals. The present data confirms that mushrooms may be used as efficient biosorbent for the removal of cadmium (II) and lead (II) ions from aqueous solution.     

The flexible PEI composites

The present study investigates the compatibilizing effect of polyphosphazene on the blends of poly(ether imide) (PEI) and thermotropic liquid crystalline polymer (Vectra‐B). FTIR study showed that there was a partial interaction or chemical reaction between the PEI and LCP in the presence of compatibilizer. Polyphosphazene is compatibilized with both PEI and LCP, which was evident from DMA results. From the X‐ray diffraction study, it has been observed that the crystalline structure of PEI–LCP blends was increased with the addition of compatibilizer. The thermal study of the composites has been studied by DTA/thermo gravimetric analyses (TGA). TGA thermograms showed an increase in decomposition temperature of PEI–LCP blends in the presence of compatibilizer. Measurement of the tensile properties showed an increase in the elongation as well as enhanced modulus and strength. From SEM micrographs of tensile fractured surfaces, the addition of compatibilizer to PEI–LCP blends was found to increase the adhesion between the matrix and the dispersed phase. POLYM. COMPOS., 27:533–538, 2006. © 2006 Society of Plastics Engineers     

Arsenic groundwater contamination and its health effects in the state of Uttar Pradesh (UP) in upper and middle Ganga plain, India: a severe danger

This communication presents results of our 2-year survey on groundwater arsenic contamination in three districts Ballia, Varanasi and Gazipur of Uttar Pradesh (UP) in the upper and middle Ganga plain, India. Analyses of 4,780 tubewell water samples revealed that arsenic concentrations in 46.5% exceeded 10 microg/L, in 26.7%, 50 microg/L and in 10% 300 microg/L limits. Arsenic concentrations up to 3,192 microg//L were observed. The age of tubewells (n=1,881) ranged from less than a year to 32 years, with an average of 6.5 years. Our study shows that older tubewells had a greater chance of contamination. Depth of tubewells (n=3,810) varied from 6 to 60.5 m with a mean of 25.75 m. A detailed study in three administrative units within Ballia district, i.e. block, Gram Panchayet, and village was carried out to assess the magnitude of the contamination. Before our survey the affected villagers were not aware that they were suffering from arsenical toxicity through contaminated drinking water. A preliminary clinical examination in 11 affected villages (10 from Ballia and 1 from Gazipur district) revealed typical arsenical skin lesions ranging from melanosis, keratosis to Bowens (suspected). Out of 989 villagers (691 adults, and 298 children) screened, 137 (19.8%) of the adults and 17 (5.7%) of the children were diagnosed to have typical arsenical skin lesions. Arsenical neuropathy and adverse obstetric outcome were also observed, indicating severity of exposure. The range of arsenic concentrations in hair, nail and urine was 137-10,900, 764-19,700 microg/kg, and 23-4,030 microg/L, respectively. The urine, hair and nail concentrations of arsenic correlated significantly (r=0.76, 0.61, and 0.55, respectively) with drinking water arsenic concentrations. The similarity to previous studies on arsenic contamination in West Bengal, Bihar and Bangladesh indicates that people from a significant part of the surveyed areas in UP are suffering and this will spread unless drives to raise awareness of arsenic toxicity are undertaken and an arsenic safe water supply is immediately introduced.     

A Novel Neurofilament Light Chain ELISA Validated in Patients with Alzheimer’s Disease,Frontotemporal Dementia,and Subjective Cognitive Decline,and the Evaluation of Candidate Proteins for Immunoassay Calibration

Neurofilament light chain (Nf-L) is a well-known biomarker for axonal damage; however, the corresponding circulating Nf-L analyte in cerebrospinal fluid (CSF) is poorly characterized. We therefore isolated new monoclonal antibodies against synthetic peptides, and these monoclonals were characterized for their specificity on brain-specific intermediate filament proteins. Two highly specific antibodies, ADx206 and ADx209, were analytically validated for CSF applications according to well-established criteria. Interestingly, using three different sources of purified Nf-L proteins, a significant impact on interpolated concentrations was observed. With a lower limit of analytical sensitivity of 100 pg/mL using bovine Nf-L as the calibrator, we were able to quantify the Nf-L analyte in each sample, and these Nf-L concentrations were highly correlated to the Uman diagnostics assay (Spearman rho = 0.97, p < 0.001). In the clinical diagnostic groups, the new Nf-L ELISA could discriminate patients with Alzheimer’s disease (AD, n = 20) from those with frontotemporal lobe dementia (FTD, n = 20) and control samples with subjective cognitive decline (SCD, n = 20). Henceforth, this novel Nf-L ELISA with well-defined specificity and epitopes can be used to enhance our understanding of harmonizing the use of Nf-L as a clinically relevant marker for neurodegeneration in CSF.