Spectrophotometric determination of indiumin zinc effluent

A new extraction-spectrophotometric method for the determination of indium at ppb level in zinc effluent is described. It is based on quantitative extraction (51.2–99.2%) of the tetrabromoindate complex with toluene solution of N,N-diphenylbenzamidine and its nine analogous from sulphuric acid solutions, which allowed the extract to react with basic dye (i.e. brilliant green, malachite green, crystal violet) solution in sequence. Among the basic dyes tested, brilliant green gave the most sensitive colour reaction. The value of molar absorptivity of the amidine bromoindate extracts with brilliant green lie in the range of (0.53–1.03)×10⁵ l mole^-1 cm^-1 at absorption maximum, 630–640. With the most sensitive compound, N-(2-methyl-phenyl)-N-phenylbenzamidine(APPBA), the detection limit of the method is 13 ppb. The method is free from interferences of almost all ions associated with indium. The method has been applied for the determination of indium to zinc-effluent.     

Effect of temperature and retention time on biomethanation of cheese whey-poultry waste-cattle dung

Various conditions, such as temperature, total solid content, cattle dung-poultry waste-cheese whey ratio, retention time and stirring, were optimized with an ultimate aim of improving anaerobic digestion. Maximum gas production (2.2 litres litre(-1) of digester day(-1)) with enriched methane content (62% CH(4)) was found with a retention time of 10 days, having a loading rate of 6.0 g total solid litre(-1) of digester day(-1) at 40 degrees C, and total solid of 6% (w/v) using a mixture of cattle dung, poultry waste and cheese whey in the ratio of 2:1:3 (w/w).     

Dynamic model for a heat exchanger tube rupture discharging a high-pressure flashing liquid into a low-pressure liquid-filled shell

Shell-tube type heat exchangers are often used to exchange heat between a high-pressure fluid and a low-pressure fluid. The pressure difference between these two fluids could be significantly high. In the event of a partial or full rupture of a tube, a problem may arise in that a transient pressure rise phenomenon could occur due to the flashing of the high-pressure sub-cooled fluid in the tube into the low-pressure shell, which may cause the shell to rupture with subsequent damage to equipment. This paper presents a dynamic model to describe the transient phenomenon occurring on the shell side following various scenarios of tube rupture. The spatial and temporal aspects of the flow transients along the pressure safety valve riser are accounted for by solving the one-dimensional continuity and momentum hyperbolic partial differential equations as applied to the liquid-filled riser. The dynamics of the attached piping system are also accounted for via two mechanistic models; the first is based on an inertial-resistive assumption of the fluids in this system, while the other is based on the assumption of anechoic perturbations passing through a long section of the attached piping. The latter is justified in cases where the attached piping is long enough such that reflections from the downstream end do not interfere with transients occurring in the shell during the initial phase of fluid flashing into the shell side following rupture. The various phases of this phenomenon are described, however the paper focuses on the initial phase of the phenomenon during which shell overpressure may be encountered. The model is applied to two ethylene heaters in tandem; the first uses propylene on the shell side to heat the ethylene on the tube side, while the second uses methanol, also on the shell side. The ratio between the shell design pressure to the tube design pressure in these two heaters are 0.169 and 0.154, respectively, hence the motivation to accurately model the transients involved in this phenomenon. The practical aspects and discussion around techniques to alleviate potential overpressure scenarios due to tube rupture are emphasized throughout the paper.     

Preparation,characterization and toxic activity of oxovanadium(IV) mixed-ligand complexes

New oxovanadium(IV) mixed-ligand complexes of the general composition [VO(L)(A)], where KHL?=?potassium salt of salicylideneglycine, A¹?=?bis(benzylidene)ethylenediamine, A²?=?bis (acetophenone)ethylenediamine, A³?=?di(2-pyridyl)amine, A⁴?=?bis(benzylidene)-1,8-diaminonaphthalene, A⁵?=?thiophene-o-carboxaldene-aniline, A⁶?=?thiophene-o-carboxaldene-p-anisidine, have been synthesized by the interaction of these ligands with vanadyl sulphate. The mixed-ligand complexes have been characterized on the basis of elemental analysis, magnetic measurements, electronic and infrared spectra. An octahedral structure has tentatively been assigned to all of the mixed-ligand complexes. The mixed-ligand complexes show higher toxic activity against the Salmonella typhi, Escherichia coli and Serratia mercescen as compared to the ligands, vanadyl sulphate and control (dimethyl sulphoxide). The mixed-ligand complexes were also tested against a standard drug (tetracycline).     

Indoor and outdoor air PBDE levels in a Southwestern US city

Levels of polybrominated diphenyl ether (PBDE) flame retardants have been increasing in humans and the environment for the past few decades. Human levels are markedly higher in the US than Europe. Although food appears to be a significant route of intake, food PBDE levels are not substantially higher in the US than Europe. House and office dust appear to be major routes of exposure with air believed to usually provide a lesser route of intake. Because there are very few measurements of airborne PBDE that have been performed in relevant microenvironments in the US, increased efforts to assess airborne PBDE in the US as sources of exposure are needed. This study reports, for the first time from a Southwestern US city in Texas, the results of measurements of airborne PBDE in multiple locations, two outdoor and six indoor (residential and office) from active air sampling with collection of a combination of both vapor- and particulate-phase PBDE. Higher PBDE levels were measured in indoor than outdoor air, which confirms previous findings. Of 11 measured congeners including BDE 209, total PBDE levels in two outdoor air samples were 112 and 125 pg m^?3 and the indoor air levels ranged from 175 to 1232 pg m^?3 with a median of 572 pg m^?3. These findings suggest that sources of air contamination with PBDE may be similar in Texas as elsewhere in North America. However, more sampling is required to (1) better determine if this is the case and (2) attempt to characterize potential sources of PBDE contamination in both indoor and outdoor air by analysis of congener patterns.     

Mercury exposure in sporadic amyotrophic lateral sclerosis patients from Ganga plain region in India: A retrospective study

Amyotrophic lateral sclerosis (ALS), a progressive disorder that usually runs a fatal course within 2–5 years of onset, is characterized by loss of motor neurons in the cortex, brain stem, and spinal cord. In this study mercury (Hg) concentrations were determined in blood samples of 40 ALS patients, of whom 24 ALS patients were from the Ganga plain region and their metal levels were found to be significantly higher. In contrast, Hg levels in the 16 ALS patients from non-Ganga plain regions whose levels were similar to those of the control subjects. Mercury in stream water samples and freshly deposited stream sediment were determined in the locations of patients’ native residences along the Ganga plain region and metal levels were found to be higher than the threshold guideline values for Hg in stream waters recommended by WHO. The geo-accumulation index in selected sites of freshly deposited stream sediment ranged from moderate to highly polluted. The high levels of Hg observed in ALS patients may potentially alter the redox status of neuronal cell components and induce cell-death pathways.     

Nerve conduction studies in sprayers occupationally exposed to mixture of pesticides in a mango plantation at Lucknow,North India

In this study, nerve conduction, organochlorine (OC) pesticide residues in blood and cholinesterase activity levels of pesticide sprayers employed in mango plantations at Lucknow, North India, were determined. Fifty-two sprayers from mango plantations who regularly spray mixture of pesticides like organophosphates (OP), OCs, and carbamates were considered as exposed group. Eighteen subjects with similar socio-economic status of exposed group, who do not handle pesticides, were selected as controls. Questionnaire-based interviews related to personal and occupational histories of the study subjects were carried out. Sprayers did not use any personal protective equipment during pesticide handling. The blood-pesticide analyses of sprayers show higher mean values of hexachlorohexane (HCH), γ-HCH, δ-HCH, total HCH, op-DDT compared with the controls. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activites were significantly reduced among sprayers. Risk of motor nerve conduction deficits was observed in sprayers with low AChE activity. Negative correlation of motor and sensory nerve conduction deficits was observed with the duration of exposure and age among sprayers. The study demonstrated that the prolonged exposure to mixture of pesticides, ergonomic factors, decline in cholinesterase activity may lead to nerve conduction dysfunction. The findings suggest the need for controlled use of pesticides in the plantation and indicated the need for training and implementation of hygiene practices like proper usage of personal protective equipments.     

Evaluation of deep learning and transform domain feature extraction techniques for land cover classification: balancing through augmentation

Environmental Science and Pollution Research - The identification of features that can improve classification accuracy is a major concern in land cover classification research. This paper compares...     

Protein futures for Western Europe: potential land use and climate impacts in 2050

Multiple production and demand side measures are needed to improve food system sustainability. This study quantified the theoretical minimum agricultural land requirements to supply Western Europe with food in 2050 from its own land base, together with GHG emissions arising. Assuming that crop yield gaps in agriculture are closed, livestock production efficiencies increased and waste at all stages reduced, a range of food consumption scenarios were modelled each based on different ‘protein futures’. The scenarios were as follows: intensive and efficient livestock production using today’s species mix; intensive efficient poultry–dairy production; intensive efficient aquaculture–dairy; artificial meat and dairy; livestock on ‘ecological leftovers’ (livestock reared only on land unsuited to cropping, agricultural residues and food waste, with consumption capped at that level of availability); and a ‘plant-based eating’ scenario. For each scenario, ‘projected diet’ and ‘healthy diet’ variants were modelled. Finally, we quantified the theoretical maximum carbon sequestration potential from afforestation of spared agricultural land. Results indicate that land use could be cut by 14–86 % and GHG emissions reduced by up to approximately 90 %. The yearly carbon storage potential arising from spared agricultural land ranged from 90 to 700 Mt CO₂ in 2050. The artificial meat and plant-based scenarios achieved the greatest land use and GHG reductions and the greatest carbon sequestration potential. The ‘ecological leftover’ scenario required the least cropland as compared with the other meat-containing scenarios, but all available pasture was used, and GHG emissions were higher if meat consumption was not capped at healthy levels.