Time saving modified BCR sequential extraction procedure for the fraction of Cd, Cr, Cu, Ni, Pb and Zn in sediment samples of polluted lake

The mobility, availability and persistence of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in contaminated lake sediment samples were evaluated by means of sequential extraction scheme, proposed by the Community Bureau of Reference protocol (BCR). The metal content in the extracts was measured by atomic absorption spectrometry. The precision and accuracy of the proposed procedure were evaluated by using a certified reference material BCR 701. The maximum recoveries for heavy metals (HMs) were observed for all three steps of BCR protocol at 32h total shaking period instead of previously reported 51h, with p>0.05. The lixiviation tests (DIN 38414-S4) were used to evaluate the leaching of HMs from sediment samples and it was observed that levels of water extractable HMs were low as compared to those values obtained by acid-soluble fraction of the BCR protocol.     

Effect of magnesium content on bioactivity of near invert phosphate-based glasses

A series of phosphate glasses 40P₂O₅-(40−x)CaO-xMgO-(20−y)Na₂O-yTiO₂ (where 0 ≤ x ≤ 24 and y = 0 or 1) with varying MgO contents were investigated for their in vitro calcium phosphate (CaP) formation. Thermal analysis of these glass compositions was conducted and a significant decrease in glass transition temperature from 448°C to 430°C was seen with reducing MgO content from 24 to 8 mol%. Degradation studies were performed in phosphate buffered saline (PBS) at 37°C, where the 8 mol% MgO glass showed the highest mass loss of around 3.4% after 28 days of immersion. Cation release studies were conducted via ion chromatography, using ultrapure water at 37°C as the degradation medium. The highest release of Ca²⁺ and Na⁺ ions was observed with the 8 mol% MgO glass. In vitro CaP formation studies were conducted using glass discs immersed in simulated body fluid (SBF) at 37°C for up to 28 days. The amorphous phase and chemical composition of deposited CaP layers on the glass discs were confirmed via X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) analysis, respectively. CaP layers with Ca/P ratio 0.8-1.1 were found to be deposited on the lower MgO content (8 to 2 mol%) glass surface after 28 days of SBF study.     

Investigation of Heat Transfer Enhancement in a Forward-Facing Contracting Channel Using FMWCNT Nanofluids

The turbulent forced convection heat transfer of water/functionalized multi-walled carbon nanotube (FMWCNT) nanofluids over a forward-facing step was studied in this work. Turbulence was modeled using the shear stress transport K-ω model. Simulations were performed for Reynolds numbers ranging from 10,000 to 40,000, heat fluxes from 1,000 to 10,000 W/m², and nanoparticle volume fractions of 0.00% to 0.25%. The two-dimensional governing equations were discretized with the finite volume method. The effects of nanoparticle concentration, shear force, heat flux, contraction, and turbulence on the hydraulics and thermal behavior of nanofluid flow were studied. The model predictions were found to be in good agreement with previous experimental and numerical studies. The results indicate that the Reynolds number and FMWCNT volume fraction considerably affect the heat transfer coefficient; a rise in local heat transfer coefficient was noted when both Reynolds number and FMWCNT volume fraction were increased for all cases. Moreover, the contraction of the channel passage leads to the formation of two recirculation regions with augmented local heat transfer coefficient value.     

Evaluation of selenium in biological sample of arsenic exposed female skin lesions and skin cancer patients with related to non-exposed skin cancer patients

The antagonistic effects between selenium (Se) and arsenic (As) suggest that low Se status plays an important role in arsenism development. The objective of present study was to assess Se contents in biological samples of As exposed females have skin lesions and cancer with related to non-exposed skin cancer patients. The biological samples (blood and scalp hair) of As exposed group comprises, female skin cancer (ESC) patients admitted in cancer hospitals have skin lesions (ESL) and exposed referents have not both diseases (ER), belongs to As exposed area of Pakistan. For comparative purposes, age matched female skin cancerous patient (RP) and non-cancerous females (NER) belong to non-exposed areas were also selected. The As and Se in acid digests of biological samples were pre-concentrated by complexing with chelating agent (ammonium pyrrolidinedithiocarbamate), and resulted complexes were extracted into non-ionic extractant (Triton X-114), prior to analysis by electrothermal atomic absorption spectrometry. The enhancement factor of about 25 was obtained by pre-concentrating 10 mL of sample solutions. The accuracy of the optimized procedure was evaluated by using certified reference material (BCR 397) with certified values for Se and As and standard addition method at three concentration levels in real samples. No significant differences was observed (p > 0.05) when comparing the values obtained by the proposed method, added and certified values of both elements. The biological samples of ESC patients had 2-3 folds higher As and lower Se levels as compared to RP (p < 0.001). Understudied exposed referents have high level of As and lower Se contents as compared to referents subjects of non-exposed area (p < 0.01). The higher concentration of As and lower levels of Se in biological samples of cancerous patients are consisted with reported studies.     

Neutrophil Extracellular Traps in Colorectal Cancer Progression and Metastasis

Neutrophils form sticky web-like structures known as neutrophil extracellular traps (NETs) as part of innate immune response. NETs are decondensed extracellular chromatin filaments comprising nuclear and cytoplasmic proteins. NETs have been implicated in many gastrointestinal diseases including colorectal cancer (CRC). However, the regulatory mechanisms of NET formation and potential pharmacological inhibitors in the context of CRC have not been thoroughly discussed. In this review, we intend to highlight roles of NETs in CRC progression and metastasis as well as the potential of targeting NETs during colon cancer therapy.     

Establishing political impact assessment: revisiting contemporary approaches with Bangladesh cases

Abstract

Despite the enormous significance of differentiated interests and power relations among the stakeholders in development interventions, political impact does not receive adequate attention and space in existing environmental impact assessment and social impact assessment frameworks. The goal of political impact assessment is to ensure democratization, participation, equity; human rights and understand the marginalization process, conflict and cooperation. Inadequate focus on political impacts like participation, marginalization and democratization could have severe impacts like increasing vulnerability and inequality. Using qualitative approaches, this study demonstrates that political impacts like lack of participation, democratization, access to service delivery and violation of human rights created and is predicted to create marginalization in case of Jamuna Bridge and Padma Bridge in Bangladesh. The paper argues that political impacts needs to be emphasized and assessed separately for facilitating more equitable distribution of benefits of infrastructure project and mitigating marginalization of individuals and communities.     

Interaction between chronic arsenic exposure via drinking water and plasma lactate dehydrogenase activity

Arsenic is a potent environmental pollutant that has caused one of the largest public health poisonings in the history of human civilization, affecting tens of millions of people worldwide especially in Bangladesh. Lactate dehydrogenase (LDH) in blood plays an important role in predicting cell or organ damage and as an important clue to the diagnosis of a variety of cancers. However, effect of chronic arsenic exposure on the LDH level in blood has not yet been documented. Since the chronic arsenic exposure is associated with organ damages and multi-site cancers, this research aimed at assaying the plasma level of LDH activity in the population who were exposed to arsenic chronically in Bangladesh. A total of 185 individuals living in arsenic-exposed areas and 121 individuals living in non-exposed area in Bangladesh were recruited as study subjects. Arsenic content in drinking water, hair and nails were estimated by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) and LDH activity was assayed by a spectrophotometer. Significant increase in LDH activity was observed with increasing concentrations of arsenic in water, hair and nails. Further, the study subjects were split into four groups based on the three ways of each exposure metrics (water, hair and nail arsenic concentrations) where the study subjects in the non-exposed area were used as a reference (lowest exposure) group. LDH activity was found to be increased in the higher exposure groups of water and hair arsenic concentrations. LDH activity was also increased at low to medium exposure groups of nail arsenic concentrations.Thus, the elevated plasma LDH activity might be helpful for the early prognosis of organ or tissue damage in the individuals who were exposed to arsenic chronically.     

Does advanced driver training improve situational awareness?

Over 70 years of experiential evidence suggests that a specific form of advanced driver training, one based on an explicit system of car control, improves driver situation awareness (SA). Five experimental hypotheses are developed. They propose that advanced driving should increase the number of information elements in the driver's working memory, increase the interconnection between those elements, increase the amount of ‘new’ information in memory as well as the prominence of existing information, and that finally, it should stimulate behaviours that help drivers evolve better situations to be aware of. An approach to SA based on Neisser's perceptual cycle theory is anchored to a network based methodology. This is applied within the context of a longitudinal on-road study involving three groups of 25 drivers, all of whom were measured pre- and post-intervention. One experimental group was subject to advanced driver training and two further groups provided control for time and for being accompanied whilst driving. Empirical support is found for all five hypotheses. Advanced driving does improve driver SA but not necessarily in the way that existing situation focused, closed loop models of the concept might predict.     

The effect of two neighboring defects on the mechanical properties of carbon nanotubes

The tensile behavior of single-walled nanotubes (SWNTs) having two defects (vacancy or Stone-Wales) positioned next to each other was simulated in this study to investigate the influence of the spatial arrangement of defects on the mechanical properties. The simulations were performed using classical molecular dynamics (MD) at the atomic scale. Two neighboring vacancy defects reduced the failure strength as much as 46% and the failure strain as much as 80% in comparison with those of pristine SWNTs, while two neighboring Stone-Wales defects reduced them as much as 34% and 70% respectively. SWNTs having two defects in the loading (axial) direction showed higher failure strength than SWNTs with defects perpendicular to the loading direction. For both types of defect, the closer the defects, the weaker the SWNTs. As result, the defect arrangement in the SWNT structure must be one of the key factors in determining its mechanical properties, as well as the population of defects.     

Erosion and thermal shock tests on ceramic materials

The resistance to erosion and thermal shock of several ceramic materials, particularly alumina, was measured. The alumina specimens were made by pressing and sintering finely ground particles. The objective was to fabricate wear-resistant components for a burner assembly used for the atomization and combustion of abrasive coal-liquid fuels. The test procedures are described, and their use demonstrated to identify a commercially available material from which shapes were prepared to a dimensional accuracy of 0.5%, of 99.5% theoretical density, and having optimized erosion and thermal shock resistance.