Betel quid chewing elevates human exposure to arsenic, cadmium and lead

Several studies have reported increased skin lesions in betel quid (a mixture of Piper betel leaves, areca nut, tobacco/flavoured tobacco, lime) chewers compared to non-chewers, exposed to arsenic (As) contaminated drinking water in Bangladesh and India. The current study has determined As, cadmium (Cd) and lead (Pb) levels of betel quids and its components using inductively coupled plasma mass spectrometry (ICP-MS). The highest concentrations of As were found in slaked lime (4.56 mg kg(-1)) followed by Piper betel leaves (0.406 mg kg(-1)) and flavoured tobacco (zarda) (0.285 mg kg(-1)), with a mean concentrations of As in betel quids of 0.035 mg kg(-1) (SD 0.02 mg kg(-1)). Mean concentrations of Cd and Pb in ordinary quids were 0.028 (SD 0.07 mg kg(-1)) and 0.423 (SD 1.4 mg kg(-1)), respectively. We estimated that a daily intake of 6 betel quids could contribute 1.2, 1.9 and 8.5% of the provisional maximum tolerable daily intake (PMDTI) for As, Cd and Pb, respectively. Since betel quid chewing is most prevalent among women, our finding raises concern that women chewers - especially pregnant chewers - may be harming their health and that of their unborn babies through increased exposure to a mixture of toxic elements (As, Cd and Pb).     

The Preparation and Characterization of Some Novel Quaternary Iminium Salts Based on Schiff-base as a Corrosion Inhibitor

Abstract

Novel quaternary iminium compounds, namely, N-(4-methoxybenzylidene)-N-benzyldodecyliminium chloride (I_a), N-(4-methoxybenzylidene)-N-benzylhexadecyl iminium chloride (I_b), N-(4-methoxybenzylidene)-N-benzyloctadecyliminium chloride (I_c), and N-benzylidene-N-benzyldodecyliminium chloride, were prepared. The surface properties such as surface and interfacial tension, foaming, and emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ_max), minimum surface area (A_min), efficiency (PC₂₀), and effectiveness (π_CMC) were calculated. Free energy of micellization (ΔG°_mic) and adsorption (ΔG°_ads) were calculated.     

Heulandite/polyaniline hybrid composite for efficient removal of acidic dye from water; kinetic,equilibrium studies and statistical optimization

Heulandite/polyaniline (HU/PANI) composite was prepared by mechanical mixing from natural heulandite and synthesized polyaniline. HU/PANI was characterized by XRD, SEM, TEM, FT-IR, and UV–Vis spectroscopy. The product is of polycrystalline nature with an average crystallite size of 25.7?nm and optical band gap of 1.69?eV. HU/PANI shows higher efficiency in the removal of light green SF dye than natural HU or PANI in the dark and under artificial illumination. The equilibrium time was attained after 360 and 480?min in the dark and under illumination, respectively. The results fitted well with pseudo second order and Elovich kinetic models. The adsorption isotherm in the dark fitted well with Langmuir isotherm model and the calculated q_max was 44.6?mg/g. Using illumination, the data fitted better with the Freundlich and Temkin model than with the Langmuir model. Based on response surface analysis, the predicted conditions for maximum removal of light green SF dye in the dark (70.9%) were 5.5?mg/L, 24?mg, 3, and 430?min for dye concentration, HU/PANI dose, pH, and contact time, respectively. Whereas, under light illumination (97%) at operating conditions of 15?mg/L, 15?mg, 3, and 589?min, respectively. The composite also shows high efficiencies in the removal of other types of acidic and basic dyes.     

The Effect of Inner Corner Radius of ECAP Die on Strain Distribution and Damage Accumulation in Deformed Sample

In the present research, the effect of inner corner radius of ECAP die on the material flow characteristic and the strain distribution inside sample were analyzed using 2D plain strain finite element simulation. Results showed that increase in inner corner radius results in the formation of smaller corner gap and narrow deformation zone. Consequently, the amount of plastic strain in regions at the bottom side of sample is increased. It is also concluded that the amount of damage factor in the upper regions of sample is higher than bottom regions and therefore cracks may initiate from these regions. In addition, the pressing force was raised by increasing inner corner radius.     

Kinetics and critical conditions for initiation of dynamic recrystallization during hot compression deformation of AISI 321 austenitic stainless steel

Dynamic recrystallization behavior of AISI 321 austenitic stainless steel were studied using hot compression tests over the range of temperatures from 900 °C to 1200 °C and strain rates from 0.001 s^-1 to 1 s^-1. The critical strain and stress for initiation of dynamic recrystallization were determined by plotting strain hardening rate vs. stress curves and a constitutive equation describing the flow stress at strains lower than peak strain. Also, the strain at maximum flow softening was obtained and the effect of deformation conditions (Z parameter) on the critical strain and stress were analyzed. Finally, the volume fraction of dynamic recrystallization was calculated at different deformation conditions using these critical values. Results showed that the model used for predicting the kinetics of dynamic recrystallization has a great consistency with the data, in the form of θ-ε curves, directly acquired from experimental flow curves.     

Clinical electroejaculation

Anejaculation is a disorder that occurs infrequently in the general population, but it occurs in some cases of spinal cord injury and dissection of retroperitoneal lymph nodes for testicular cancer. It is associated with multiple sclerosis, transverse myelitis, and diabetes mellitus. Electroejaculation, which involves electrodes in a probe placed in the rectum, electrically stimulates emission of seminal fluid. Semen thus obtained can be used for artificial insemination if a patient and his spouse wish to become natural parents.     

Study of some physical properties of bulk CuGa x In1−x Se2

Structural electrical, and optical properties of polycrystalline bulk samples of CuGa _x In_1–x Se₂ (0.75x0) were studied as a function of composition. The homogeneity of the constituents is tested using microprobe analysis. The lattice parameters a and c vary linearly with the change of Ga composition but the c/a values depart from a linear variation. The constructed phase diagram was reported from X-ray and differential thermal analysis measurements. All investigated samples are p-type and the electrical conductivity , carrier concentration p, and Hall mobility _H decrease while the thermoelectric power Q increase as the Ga content (x) increases. The energy gap values obtained from diffused reflection measurements, exhibit bowing behavior expressed by the relationship E _g(x)=1.066+0.464x+0.144x ².     

Simulation of an Atmospheric Residue Desulfurization Unit by Quasi-Steady State Modeling

The current trend in petroleum refining is to maximize the conversion of the bottom of the barrel to improve the profitability of the refinery. Atmospheric residue desulfurization (ARDS) plays a key role in this, especially, when processing crudes with moderate to high sulfur contents. A deterministic quasi-steady state model has been developed to simulate the long term behavior of the reaction section of an atmospheric residue desulfurization (ARDS) unit, consisting of four co-current catalytic trickle bed reactors in series. The model uses the properties of the feedstock and the catalyst and is capable of simulating profiles of sulfur, coke, and metal depositions and the temperature along the reactors, taking into account also catalyst deactivation. Hydrogen quenching has also been simulated and simulation results predict all the essentials of the long term behavior of both experimental and industrial scale ARDS reactors satisfactorily. Comparing the simulation results with actual commercial data, the model predicted perfectly the middle part of the run. The model is unable to simulate the End-of-Run conditions due to pore mouth plugging phenomenon.     

Copolyesters of poly(ethylene terephthalate), hydroquinone diacetate,and terephthalic acid: A simple rate model for catalyzed synthesis in melt

Transesterification reactions between poly(ethylene terephthalate) (PET), hydroquinone diacetate (HQDA), and terephthalic acid (TA), were conducted via the melt polymerization route with the objective of analyzing the copolyesterification kinetics of a phase separated system. At first homopolymerization of HQDA and TA were conducted at 50 mol % composition of each monomer. Then the polymerization kinetics of four compositions [PET 30/70 (HQDA + TA), PET 40/60 (HQDA + TA), PET 50/50 (HQDA + TA), PET 60/40 (HQDA + TA) with 30 : 35 : 35, 40 : 30 : 30, 50 : 25 : 25, and 60 : 20 : 20 mol % PET, HQDA, and TA] were investigated. The following assumptions were made to make kinetic analysis tractable. HQDA and TA combine to form acetic acid and higher oligomers. The oligomer subsequently adds on to the PET chain to give a copolymer of PET/HQDA/TA, the product of interest. The reaction between PET, HQDA, and TA proceeds in a heter-ogeneous two-phase system consisting of PET-rich and PET-poor regions. The reaction sequence is HQDA and TA react to form a dimer and subsequently the dimer is added onto the PET chain. This reaction sequence is assumed to be valid for the PET-rich and PET-poor phases. Both these reactions were assumed to be second order with respect to the reactants. Reactions wherein the dimer reacts with HQDA or TA to form acetic acid exist, but the probabilities of these processes are small with respect to the main reaction postulated above, thus maintaining the overall mass balance. Moles of acetic acid found experimentally were computed using a standard procedure. The rate constant k under the conditions of phase separation was determined. The rate constant in the presence of PET was higher than that observed in the HQDA and TA reaction. An Arrhenius plot revealed that the catalyst plays a marginal role. Microscopic analysis revealed that the HQDA and TA polymer were nonmelting while copolyesters PET 30/70 (HQDA + TA) to PET 60/40 (HQDA + TA) melted and were liquid crystalline. © 1996 John Wiley & Sons, Inc.