In Situ Abiotic Detoxification and Immobilization of Hexavalent Chromium

Detailed site characterization data from the former electroplating shop at the U.S. Coast Guard Air Support Center, Elizabeth City, North Carolina, suggested that the elevated Cr(VI) in the capillary fringe area had contaminated the ground water at the site. Most of the mobile Cr(VI) is present in the capillary fringe zone of the aquifer under an oxidizing environment. Current literature suggests that the reduction of Cr(VI) to Cr(Ill) through in situ redox manipulation in the presence of a reductant is an innovative technique for remediating chromate-contaminated sediments and ground water. The objective of this study was to evaluate the effectiveness of sodium dithionite in creating a reductive environment to remediate Cr(VI) present in soil. Sodium dithionite, a strong reductant, was injected into a small area of the vadose zone where elevated Cr(VI) was identified. Several striking changes observed in the target zone during the post-injection monitoring periods include a significant decrease in Eh(SHE), as much as ~ 700 m V, absence of dissolved oxygen for 48 weeks, and the increase of Fe(II) concentrations. Results indicated that the in situ remedial treatment of Cr(VI) in the capillary fringe area was effective and consequently the concentration of Cr(VI) in ground water dropped below the MCLG level. This research demonstrated the effectiveness of in situ abiotic remediation by reducing Cr(VI) concentrations, mobility, and toxicity in soils and ground water within a short period of time. Therefore, sodium dithionite would be a feasible and cost-effective option for a full-scale remedial approach for the contaminated site at the U.S. Coast Guard Facility

Enterotoxigenic Escherichia coli and Vibrio cholerae Diarrhea, Bangladesh, 2004

Flooding in Dhaka in July 2004 caused epidemics of diarrhea. Enterotoxigenic Escherichia coli (ETEC) was almost as prevalent as Vibrio cholerae O1 in diarrheal stools. ETEC that produced heat-stable enterotoxin alone was most prevalent, and 78% of strains had colonization factors. Like V. cholerae O1, ETEC can cause epidemic diarrhea

Vibrio cholerae in rural and urban Bangladesh, findings from hospital-based surveillance, 2000–2021

With more than 100,000 cases estimated each year, Bangladesh is one of the countries with the highest number of people at risk for cholera. Moreover, Bangladesh is formulating a countrywide cholera-control plan to satisfy the GTFCC (The Global Task Force on Cholera Control) Roadmap\u27s goals. With a particular focus on cholera trends, variance in baseline and clinical characteristics of cholera cases, and trends in antibiotic susceptibility among clinical isolates of Vibrio cholerae, we used data from facility-based surveillance systems from icddr,b’s Dhaka, and Matlab Hospitals from years 2000 to 2021. Female patients comprised 3,553 (43%) in urban and 1,099 (51.6%) in rural sites. Of the cases and most patients 5,236 (63.7%) in urban and 1,208 (56.7%) in the rural site were aged 15 years and more. More than 50% of the families belonged to the poor and lower-middle-class; in 2009 (24.4%) were in urban and in 1,791 (84.2%) were in rural sites. In the urban site, 2,446 (30%) of households used untreated drinking water, and 702 (9%) of families disposed of waste in their courtyard. In the multiple logistic regression analysis, the risk of cholera has significantly increased due to waste disposal in the courtyard and the boiling of water has a protective effect against cholera. Rotavirus (9.7%) was the most prevalent co-pathogen among the under-5 children in both sites. In urban sites, the percentage of V. cholerae along with co-existing ETEC and Campylobacter is changing in the last 20 years; Campylobacter (8.36%) and Enterotoxigenic Escherichia coli (ETEC) (7.15%) were the second and third most prevalent co-pathogens. Shigella (1.64%) was the second most common co-pathogen in the rural site. Azithromycin susceptibility increased slowly from 265 (8%) in 2006–2010 to 1485 (47.8%) in 2016–2021, and erythromycin susceptibility dropped substantially over 20 years period from 2,155 (98.4%) to 21 (0.9%). Tetracycline susceptibility decreased in the urban site from 2051 (45.9%) to 186 (4.2%) and ciprofloxacin susceptibility decreased from 2,581 (31.6%) to 1,360 (16.6%) until 2015, then increased 1,009 (22.6%) and 1,490 (18.2%) in 2016–2021, respectively. Since 2016, doxycycline showed 902 (100%) susceptibility. Clinicians need access to up-to-date information on antimicrobial susceptibility for treating hospitalized patients. To achieve the WHO-backed objective of eliminating cholera by 2030, the health systems need to be put under a proper surveillance system that may help to improve water and sanitation practices and deploy oral cholera vaccines strategically

Enhancement of mechanical and corrosion resistance properties of electrodeposited Ni–P–TiC composite coatings

In the present study, the effect of concentration of titanium carbide (TiC) particles on the structural, mechanical, and electrochemical properties of Ni–P composite coatings was investigated. Various amounts of TiC particles (0, 0.5, 1.0, 1.5, and 2.0 g L−1) were co-electrodeposited in the Ni–P matrix under optimized conditions and then characterized by employing various techniques. The structural analysis of prepared coatings indicates uniform, compact, and nodular structured coatings without any noticeable defects. Vickers microhardness and nanoindentation results demonstrate the increase in the hardness with an increasing amount of TiC particles attaining its terminal value (593HV100) at the concentration of 1.5 g L−1. Further increase in the concentration of TiC particles results in a decrease in hardness, which can be ascribed to their accumulation in the Ni–P matrix. The electrochemical results indicate the improvement in corrosion protection efficiency of coatings with an increasing amount of TiC particles reaching to ~ 92% at 2.0 g L−1, which can be ascribed to a reduction in the active area of the Ni–P matrix by the presence of inactive ceramic particles. The favorable structural, mechanical, and corrosion protection characteristics of Ni–P–TiC composite coatings suggest their potential applications in many industrial applications

Compositional analysis of chalcopyrite using calibration-free laser-induced breakdown spectroscopy

Thisarticlepresentselementalanalysisofaneconomicallyimportantmineral(chalcopyrite) oflocalorigin. Calibration-freelaser-inducedbreakdownspectroscopy(CF-LIBS)methodologybased on the assumption of optically thin plasma and local thermodynamic equilibrium was employed for quantitative analysis. Plasma on the surface of the chalcopyrite target was generated by an Nd:YAG laser beam of wavelength 532 nm, pulse width 5 ns, and operated at repetition rate of 10 Hz. A LIBS2000+ detection system, comprised of five spectrometers, covering the spectral range from 200–720 nm, was used to record the signal of the optical emission from the chalcopyrite plasma. Recorded optical spectrum revealed the presence of Cu and Fe as the major elements while Ca and Na were recognized as the minor elements in the target sample. Quantitative analysis has shown that the relative concentrations of Cu, Fe, and Ca in the sample under study were 58.9%, 40.2%, and 0.9% by weight respectively. However, Na was not quantified due to the unavailability of suitable spectral lines, required for CF-LIBS analysis. Results obtained by CF-LIBS were validated by X-ray fluorescence (XRF) analysis, which showed the presence of five compositional elements viz. Cu, Fe, Si, Se and Ag with weight percentages of 58.1%, 35.4%, 5.7%, 0.7%, and 0.1% respectively. These results endorse the effectiveness of the CF-LIBS technique for quantitative analysis of major elements, however, its usefulness in case of minor and trace elements needs further improvement

Facile synthesis of high-quality Nano-size 10B-enriched fibers of hexagonal boron nitride

The interesting properties of hexagonal boron nitride (h-BN) and its potential uses in thermo-structural advanced applications have been limited or restricted by its inherent brittleness, which can easily be eliminated by its fibers (h-BN) in nanoscale dimensions. The current study is based on the synthesis of nanoscale 10B-enriched fibers of h-BN (10BNNFs) from 10B in the precursors instead of B in two-hour annealing at 900 °C and one-hour growth at 1000 °C. All of the 10BNNFs are randomly curved and highly condensed or filled from 10h-BN species with no internal space or crack. XRD peaks reported the 10h-BN phase and highly crystalline nature of the synthesized 10BNNFs. 10h-BN phase and crystalline nature of 10BNNFs are confirmed from high-intensity peaks at 1392 (cm−1) in Raman and FTIR spectroscope

Impact of Rapid Urbanization on the Rates of Infection by Vibrio cholerae O1 and Enterotoxigenic Escherichia coli in Dhaka, Bangladesh

Bangladesh is a country where acute dehydrating diarrhea or cholera is common and is seen at least two times every year and additionally in natural disasters. In addition cholera cases have increased in the country, especially in urban settings such as in the capital city, Dhaka, where the number of hospitalized patients with more severe disease has tremendously increased. In the present observation, we have concentrated on determining the occurrence of diarrhoea caused by the two most common bacterial agents V. cholerae O1 and enterotoxigenic Escherichia coli (ETEC) in a densely populated, disease prone area Mirpur in Dhaka for two years from March 2008 to February 2010. Stool or rectal specimens from diarrheal patients coming to the ICDDR,B hospital from Mirpur were tested for the two bacterial pathogens. We found that V. cholerae O1 was the major bacterial pathogen and a cause of severe cholera disease in 23% of patients (2,647 of a total of 11,395 patients) from Mirpur. We surmise that cholera vaccines, as well as other public health tools that can target such high risk groups in the country, will be able to reduce the disease morbidity and the transmission of pathogens to improve the quality of life in urban settings

Arsenic Exposure and Motor Function among Children in Bangladesh

Background: Several reports indicate that drinking water arsenic (WAs) and manganese (WMn) are associated with children’s intellectual function. Very little is known, however, about possible associations with other neurologic outcomes such as motor function