Anirban Biswas

Nutritional deficiency and arsenical manifestations: a perspective study in an arsenic-endemic region of West Bengal, India.

OBJECTIVE To assess whether nutritional deficiency increases susceptibility to arsenic-related health effects. DESIGN Assessment of nutrition was based on a 24 h recall method of all dietary constituents. SETTING Epidemiological cross-sectional study was conducted in an arsenic endemic area of West Bengal with groundwater arsenic contamination. SUBJECTS The study was composed of two groups – Group 1 (cases, n 108) exhibiting skin lesions and Group 2 (exposed controls, n 100) not exhibiting skin lesions – age- and sex-matched and having similar arsenic exposure through drinking water and arsenic levels in urine and hair. RESULTS Both groups belonged to low socio-economic strata (Group 1 significantly poorer, P<0·01) and had low BMI (prevalence of BMI<18·5 kg/m2: in 38% in Group 1 and 27% in Group 2). Energy intake was below the Recommended Daily Allowance (set by the Indian Council of Medical Research) in males and females in both groups. Increased risk of arsenical skin lesions was found for those in the lowest quintile of protein intake (v. highest quintile: OR=4·60, 95% CI 1·36, 15·50 in males; OR=5·62, 95% CI 1·19, 34·57 in females). Significantly lower intakes of energy, protein, thiamin, niacin, Mg, Zn and choline were observed in both males and females of Group 1 compared with Group 2. Significantly lower intakes of carbohydrate, riboflavin, niacin and Cu were also observed in female cases with skin lesions compared with non-cases. CONCLUSIONS Deficiencies of Zn, Mg and Cu, in addition to protein, B vitamins and choline, are found to be associated with arsenical skin lesions in West Bengal.

Evaluation of dietary arsenic exposure and its biomarkers: A case study of West Bengal, India

Few reports are available that characterize daily arsenic exposure through water and diet among people living in groundwater-contaminated regions and correlate it with biomarkers. The present study describes the total individual arsenic exposure and arsenic level in urine and hair of such an arsenic-exposed population in West Bengal. Demographic characteristics and the total daily arsenic intake through water and diet were determined in 167 (Group-1 participants selected from arsenic endemic region) and 69 (Group-2 participants selected from arsenic non-endemic region) in West Bengal. Out of 167 Group-1 participants 78 (Group-1A) had arsenical skin lesions while 89 Group-1B) had no such lesion. Arsenic level in water samples as well as diet, urine and hair samples, collected from all the individual participants, were estimated. The mean value of estimated total arsenic content from water and diet was 349 (range: 20–1615) μg/day in 167 (Group-1) participants living in As endemic region [As in water: mean value 54 (range:BDL-326) μg/L] and 36 (range:12–120) μg/day in 69 (Group-2) participants living in As non-endemic region (As in water: below detection level (BDL), < 0.3 μg/L). Estimated mean arsenic level in urine in these two groups of participants was 116 (range: 6–526) μg/L and 17 (range: BDL-37) μg/L and in hair was 1.0 (range: 0.22–3.98) mg/Kg and 0.16 (range: 0.06–0.37) mg/Kg, respectively. Multiple regressions analysis in Group-1 participants showed that total arsenic intake was associated significantly with urinary and hair arsenic level. The estimated regression coefficient was 0.0022 (95% confidence interval, C.I: 0.0016, 0.0028; P < 0.001) and 0.0024 (95% C.I: 0.0021, 0.003; P < 0.001), respectively. In sub group analysis, higher median urinary arsenic value relative to arsenic intake through water and diet was observed in 78 Group-1A subjects with skin lesion compared to urinary arsenic value in 89 Group-1B subjects without skin lesions, though there was a marginal difference of median total arsenic intake in these two groups. This study showed that significant elevation of arsenic level in urine and hair was associated with elevated arsenic intake through water and diet in people living in arsenic endemic region (Group-1), while these values were low in people living in non-endemic region (Group-2). Those with skin lesions were found to have higher arsenic in urine and hair compared to those without skin lesion with similar arsenic intake through water and diet.

Dietary arsenic exposure with low level of arsenic in drinking water and biomarker: A study in West Bengal

The authors investigated association of arsenic intake through water and diet and arsenic level in urine in people living in arsenic endemic region in West Bengal supplied with arsenic-safe water (<50 μg L−1). Out of 94 (Group-1A) study participants using water with arsenic level <50 μg L−1, 72 participants (Group-1B) were taking water with arsenic level <10 μg L−1. Multiple regressions analysis conducted on the Group-1A participants showed that daily arsenic dose from water and diet were found to be significantly positively associated with urinary arsenic level. However, daily arsenic dose from diet was found to be significantly positively associated with urinary arsenic level in Group-1B participants only, but no significant association was found with arsenic dose from water in this group. In a separate analysis, out of 68 participants with arsenic exposure through diet only, urinary arsenic concentration was found to correlate positively (r = 0.573) with dietary arsenic in 45 participants with skin lesion while this correlation was insignificant (r = 0.007) in 23 participants without skin lesion. Our study suggested that dietary arsenic intake was a potential pathway of arsenic exposure even where arsenic intake through water was reduced significantly in arsenic endemic region in West Bengal. Observation of variation in urinary arsenic excretion in arsenic-exposed subjects with and without skin lesion needed further study.

Species-level study on arsenic availability from dietary components

Arsenic (As) contaminated water and foodstuffs are of major concern. Samples of drinking–cooking water (n = 50), raw rice (n = 50), common vegetables (eight types), and common pulses (three types) were collected from households in the endemic region. The study found up to 70% As reduction by using safe water for cooking of rice and vegetables. Speciation study reflected more arsenate than arsenite and other organic arsenicals in all the types of samples. Male intake of 293 μg As through drinking water contained 38 μg arsenite and 246 μg arsenate, and female intake of 199 μg As contained 167 μg arsenate and 25 μg arsenite. In cooked rice, 108 μg As contained 69 μg arsenate and 17 μg arsenite with 9 μg dimethylarsonic acid (DMA). Total As consumption from cooked vegetables was 45 μg with 34 and 4 μg of arsenite and arsenate, respectively, and 5 μg of DMA. Data indicate that cooking with As-free water removes arsenic in already contaminated foodstuffs but without interconversion of the As species, from toxic inorganic to less toxic organic forms.

Effect of safe water on arsenicosis: A follow-up study

Background: Arsenic pollution in groundwater, used for drinking purposes, has been envisaged as a problem of global concern. Treatment options for the management symptoms of chronic arsenicosis are limited. Mitigation option available for dealing with the health problem of ground water arsenic contamination rests mainly on supply of arsenic safe water in arsenic-endemic region of Indo-Bangladesh subcontinent. Limited information is available regarding the long-term effect of chronic arsenic toxicity after stoppage of consumption of arsenic-containing water. Objective: The current study was, therefore, done to assess, objectively, the effect of drinking arsenic safe water (<50 μg/L) on disease manifestation of arsenicosis. Results: Manifestations of various skin lesions and systemic diseases associated with chronic arsenic exposure were ascertained initially by carrying on baseline study on 208 participants in Nadia (Cohort-I, with skin lesion and Cohort-II, without skin lesion) using a scoring system, as developed by us, and compared objectively at the end of each year for 3 year follow-up period. All the participants who had arsenic contaminated drinking water source in their houses were supplied with arsenic removal filters for getting arsenic-free water during the follow-up period. In participants belonging to Cohort-I, the skin score was found to improve significantly at the end of each year, and it was found to be reduced significantly from 2.17 ± 1.09 to 1.23 ± 1.17; P < 0.001 at the end of 3 years intervention study indicating beneficial effect of safe water on skin lesions. The systemic disease symptom score was also found to improve, but less significantly, at the end of 3 years in both the cohorts. Most important observation during the follow-up study was persistence of severe symptoms of chronic lung disease and severe skin lesion including Bowens disease in spite of taking arsenic-safe water. Further, death could not be prevented to occur because of lung cancer and severe lung disease. Conclusion: It is, therefore, an urgent need to make arrangement for availability of safe water source among the arsenic-affected people in the district. Many of the people in the affected villages are not aware of contamination of their home tube wells with arsenic. Awareness generation and motivation of the people for testing their drinking water sources for arsenic and environmental interventions like rain water harvesting, ground water recharge, and restricting excessive use of ground water for domestic and agricultural purposes are also important to prevent further exposure of arsenic to these people.

Chemical oxidation of Ti–6Al–4V for improved wear and corrosion resistance

Abstract In the present study, chemical oxidation of Ti–6Al–4V has been carried out by dipping it in varying concentrations of hydrogen peroxide (0˙04–0˙08M) for 30 min. Chemically oxidised samples were also subjected to isothermal heat treatment in air at 400°C for one hour followed by slow cooling in the furnace. Chemical oxidation developed an oxide film on the surface of Ti–6Al–4V consisting of Ti2O3 and TiO2 (anatase), the volume fraction on anatase increases with increase in solution concentration. Subsequent heat treatment causes formation of rutile phase. The microhardness of the oxidised surface is increased to 475 VHN as compared to 290 VHN of the as received Ti–6Al–4V. Wear and corrosion resistance were improved following oxidation. It was observed that chemical treatment in 0˙08M hydrogen peroxide solution followed by heat treatment at 400°C led to a maximum improvement in wear and corrosion resistance.

Fabrication of wearable semiconducting piezoelectric nanogenerator made with electrospun-derived zinc sulfide nanorods and poly(vinyl alcohol) nanofibers

We report the fabrication of flexible, low cost, and wearable piezoelectric nanogenerators (NG) composed of a poly(vinyl alcohol) (PVA) nanofiber web and oriented zinc sulfide (ZnS) nanorods (NRs) by a facile and scalable electrospinning technique. The piezoelectric performance of the NG is found to be increased by simply stacking the nanofiber web mats, where the ZnS NRs are incorporated in the PVA fiber matrix. Furthermore, we also designed a large area wearable nanogenerator (WNG) to harvest mechanical energy from acoustic random vibrations and convert it into electrical energy, and an improved acoustic sensitivity of 2 V Pa−1 is observed. This indicates that the WNG is ultrasensitive to random mechanical vibration, and possesses potential utility as a sustainable power source and sensitive pressure sensor particularly suited for portable electronics and wearable technology.

LASER ASSISTED SURFACE MODIFICATION OF Ti–6Al–4V FOR BIOIMPLANT APPLICATION

The present study aims at enhancing the wear resistance of Ti–6Al–4V by laser surface nitriding. Laser surface treatment has been carried out by melting of the sand blasted Ti–6Al–4V substrate using a high power continuous wave Diode laser with nitrogen as shrouding environment (at a gas flow rate of 51/min). Laser surface nitriding led to formation of dendrites of titanium nitrides. The microhardness is improved to a maximum of 900–950 VHN (Vickers hardness number) in laser surface nitriding as compared to 260 VHN of the as-received substrate. Surface nitriding increased primary potential for pit formation (Epp1) as compared to Ti–6Al–4V. Biocompatibility behavior showed a better cell viability due to surface nitriding as compared to the as-received Ti–6Al–4V.

Comparison of the thermal stability of the α, β and γ phases in poly(vinylidene fluoride) based on in situ thermal Fourier transform infrared spectroscopy

ABSTRACT The electroactive β phase of poly(vinylidene fluoride) (PVDF) is induced due to the aging time of PVDF solutions. The feasibility of the combination of the three crystalline polymorphs (α, β and γ) is demonstrated where their relative proportion within the PVDF film can be tailored by the simple monitoring of the preparation conditions. To identify all these phases, Fourier transform infrared (FT-IR) spectroscopy is carried out and it is spotlighted that the vibrational bands at 510 and 841 cm−1 are not sufficient to state the formation of the β phase. The main aim of this work is devoted to develop a better understanding on the thermal stability of these several phases of PVDF, which has a longstanding ambiguity persisting in this area. It has been found that the in situ thermal FT-IR spectroscopy is one of the best alternatives to understand this important issue. It is ascertained that the β phase is the least thermally stable phase among α, β and γ phases, whereas the γ phase is the most thermally stable phase.

An improved performance analysis of the boost converters

The paper plays an important matter on harmonics how to diorite the power quality, stability and performance of the power system mainly administering with the non-linear loads so the substantial haphazard harmonics elimination techniques are inevitable to conserve the good quality of electrical power for the utility and consumer agreement using the most economical boost power converters engine which is widely utilized to improve the power factor, huge harmonics abolition and power quality of the power distribution systems as an integral part of the electricity.