Respiratory effects in people exposed to arsenic via the drinking water and tobacco smoking in southern part of Pakistan

In this study, a survey has been conducted during 2005-2007 on surface and groundwater arsenic (As) contamination and its impact on the health of local population, of villages located on the banks of Manchar lake, southern part of Sindh, Pakistan. We have also assessed the relationship between arsenic exposure through respiratory disorders in male subjects with drinking water and smoking cigarettes made from tobacco grown in agricultural land irrigated with As contaminated lake water. The biological samples (blood and scalp hair) were collected from As exposed subjects (100% smokers) and age matched healthy male subjects (40.2% smoker and 59.8% non smokers) belong to unexposed areas for comparison purposes. The As concentration in drinking water (surface and underground water), agricultural soil, cigarette tobacco and biological samples were determined by electrothermal atomic absorption spectrometry. The range of As concentrations in lake water was 35.2-158 µg/L (average 97.5 µg/L), which is 3-15 folds higher than permissible limit of World Health Organization (WHO, 2004). While the As level in local cigarette tobacco was found to be 3-6 folds higher than branded cigarettes (0.37-0.79 µg/g). Arsenic exposed subjects (with and without RD) had significantly elevated levels of As in their biological samples as compared to referent male subject of unexposed area. These respiratory effects were more pronounced in individuals who had also As induced skin lesions. The linear regressions showed good correlations between As concentrations in water versus hair and blood samples of exposed subjects with and without respiratory problems.     

Streamlined life cycle assessment of residue utilization options in <Emphasis Type="Italic">Tongkat Ali </Emphasis>(<Emphasis Type="Italic">Eurycoma longifolia</Emphasis>) water extract manufacturing process

Life cycle assessment (LCA) is often used to compare alternative process options in terms of their overall impact on the environment to easily identify the most environmentally friendly alternative. In this work, a streamlined LCA study was conducted to assess three different residue utilization schemes for Tongkat Ali (Eurycoma longifolia) extract production. The case study was firstly simulated using a batch process simulation software. The results of mass and energy balances obtained from the simulation software were then subjected to life cycle analysis. By evaluating the different schemes for using the fibrous residue from the extraction process, the potential for environmental process improvement was identified. Overall, use of the residue as process fuel was found to be the most environmentally friendly option. It produces the least emissions and reduces resource usage per unit of product than the other options evaluated.     

Electroless plating of moisture‐curable polyurethane undercoating films

The compatibility of using moisture‐curable polyurethane (MCPU) system as a thin undercoating layer with electroless plating process was evaluated. The characteristics of the MCPU before and after chemical etching treatment were analyzed using atomic force microscope (AFM), scanning electrode microscope (SEM), contact‐angle measurements, and (Fourier‐Transform Infrared) FTIR spectroscopy. We found that surface morphology and roughness of the MCPU is affected by curing period and etching times. A proper combination of curing period and etching times are critical for obtaining a fully metallized surface. All MCPU samples that were etched for 15 min show poor plating performance due to surface damage caused by mild etching treatment. A standard pull‐off testing method (ASTM 4541) was used to evaluate the adhesion strength of nickel–MCPU. Only samples that were postcured for 4 days show influence of surface roughness on adhesion strength. On average, samples that were postcured for 7 days before electroless plating showed better adhesion of nickel–MCPU compared with samples that were postcured for 2 or 4 days. The results show that MCPU system can be used as a thin undercoating layer for electroless plating. It also offers smooth metal–polymer interface and therefore has the potential to be exploited for use in many electroless plating applications including in the decorative such as ornaments and display items and also in electronic industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1554–1565, 2007     

Engineering electrospun nanofibrillar surfaces for spinal cord repair: a discussion

BACKGROUND: The design of implants comprised of biodegradable electrospun nanofibers for the purpose of bridging injuries in damaged spinal cord is discussed. Electrospun nanofibers structurally mimic the extracellular matrix on which neurons and other cell types grow in vivo. This property has created great interest for their use in tissue engineering applications. However, their employment as biomimetic surfaces for such in vivo applications is still in its infancy. RESULTS: A nonwoven fabric comprised of electrospun polyamide nanofibers supported modest axonal regeneration in injured adult rat spinal cord. Covalent modification of the nanofibers with a bioactive peptide derived from the neuroregulatory extracellular matrix molecule tenascin‐C enhanced the ability of the nanofibers to facilitate axonal regrowth. However, the random orientation of the nanofibrillar fabric folds was an impediment to the forward movement of axons. CONCLUSIONS: Polyamide nanofibers covalently modified with neuroactive molecules provide a promising material for grafts to promote spinal cord regeneration. However, for the proper guidance of regrowing axons, attention must be paid to the engineering of ordered nanofibrillar structures. Copyright © 2007 Society of Chemical Industry     

Optimization of phototrophic hydrogen production by Rhodopseudomonas palustris PBUM001 via statistical experimental design

Phototrophic hydrogen production by indigenous purple non-sulfur bacteria, Rhodopseudomonas palustris PBUM001 from palm oil mill effluent (POME) was optimized using response surface methodology (RSM). The process parameters studied include inoculum sizes (% v/v), POME concentration (% v/v), light intensity (klux), agitation (rpm) and pH. The experimental data on cumulative hydrogen production and COD reduction were fitted into a quadratic polynomial model using response surface regression analysis. The path to optimal process conditions was determined by analyzing response surface three-dimensional surface plot and contour plot. Statistical analysis on experimental data collected following Box-Behnken design showed that 100% (v/v) POME concentration, 10% (v/v) inoculum size, light intensity at 4.0 klux, agitation rate at 250 rpm and pH of 6 were the best conditions. The maximum predicted cumulative hydrogen production and COD reduction obtained under these conditions was 1.05 ml H₂/ml POME and 31.71% respectively. Subsequent verification experiments at optimal process values gave the maximum yield of cumulative hydrogen at 0.66 ± 0.07 ml H₂/ml POME and COD reduction at 30.54 ± 9.85%.     

An ultraviolet phosphor from submicrometer-sized particles of gadolonium-doped yttrium oxide prepared by heating of precursors in a polymer solution

Gadolonium-doped yttrium oxide (Y₂O₃:Gd) was synthesized by simple heating of precursors in a polymer solution. This material is potentially useful as an ultraviolet source, since ultraviolet light is emitted when electron transition between energy states in Gd ions occurs. The grain sizes of the particles were found to be sub-micron down to several tens of nanometers. Optimum conditions for producing highly crystalline material with small grain and crystal sizes was investigated by varying the parameters for the synthesis, such as heating temperature, heating time, and dopant concentration. A heating temperature at 800 °C and a heating time of 30 min was optimum, i.e., appreciably high crystallinity and small grain sizes were produced. The particles produce ultraviolet light, peaking at 315 nm, and the intensity of the light depends on the dopant concentration. The maximum intensity was achieved at a dopant concentration of 5 to 10% at./at.     

Modeling and optimization of lipase‐catalyzed synthesis of dilauryl adipate ester by response surface methodology

BACKGROUND: Adipate esters are used as low‐temperature and low‐viscosity plasticizers for polyvinyl chloride and its copolymers. In this work, optimization of lipase‐catalyzed production of dilauryl adipate was carried out using response surface methodology (RSM) based on a four‐factor‐five‐level central composite rotatable design (CCRD). Immobilized lipase from Candida antarctica (Novozym 435) was used as catalyst in this reaction. Various reaction parameters affecting the synthesis of adipate ester, including alcohol/acid molar ratio, amount of enzyme, temperature and reaction time, were investigated. RESULTS: Statistical analysis showed that the amount of enzyme was less significant than the other three factors. The optimal conditions for the enzymatic reaction were obtained at 5.7:1 substrate molar ratio using 0.18 g of enzyme at 53.1 °C for 282.2 min. Under these conditions the esterification percentage was 96.0%. CONCLUSIONS: The results demonstrated that response surface methodology can be applied effectively to optimize the lipase‐catalyzed synthesis of adipate ester. The optimum conditions can obtained be used to scale up the process. Copyright © 2008 Society of Chemical Industry     

Magnesium-doped ZnO nanorod electrolyte–insulator–semiconductor (EIS) sensor for detecting calcium ions

Electrolyte-Membrane-Insulator-Semiconductor (EMIS) sensors based on ZnO undoped and doped with a different molar ratio of Mg/Zn are demonstrated to detect calcium ions. The samples grown on the silicon substrates by the hydrothermal method were characterized to explore the impact of Mg content on the structural and compositional characteristics and sensing performance by X-ray diffraction analysis, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The results indicated that the EIMS based on ZnO nanorods doped with 3% Mg had a high Ca²⁺ ion sensitivity (69 mV/decade) and linearity (99.8%). In addition, the samples have good stability with a low drift rate of 0.398 mV/h and possess great selectivity over other interference ions such as Na⁺, K⁺, Mg²⁺, and Ni²⁺ due to the employment of an ionophore membrane.