Chemical weathering of pyrite via oxidative dissolution is well-known for generating Fe(III)-bearing colloids at acid mine drainage (AMD) sites; however, the potential for physical weathering of ...pyrite-bearing materials and subsequent release and transport of colloidal pyrite and associated trace metals has not been studied. Here, we monitored the colloidal metal transport in soil developing on abandoned coal mine spoil with a history of AMD generation to systematically study the contribution of colloids to base and trace metal transport and determine the elemental and mineralogical composition of colloids. We collected soil pore water using lysimeters with a pore size of approximately 1.3 μm and centrifugation was used to separate the colloids from aqueous fractions. Metal concentrations of Na, Ca, Mg, K, Si, Al, Mn, Fe, Cu, and Zn were analyzed. Our results show only 14% of the total Al and Cu were present in colloidal fractions whereas 23%, 43%, and 54% of Fe, Mn, and Zn were transported in the colloidal phase, respectively. In contrast, all base metals were primarily present in the aqueous concentration with a small fraction (<10%) present in the colloidal phase. The colloidal fractions of the base metals were inferred to be associated with the concentration of clay colloids. The release of colloids exhibited possible sensitivity toward weather conditions such as alternating high temperatures and rainfall during summer (May–July) compared to fall (August–November). The morphology, elemental, and mineral composition of colloids were determined by a scanning electron microscopy equipped with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Colloids were dominated by phyllosilicates (biotite, muscovite, and kaolinite) with minor quartz and feldspars. Other minerals phases identified in colloidal fractions were hematite, goethite, arsenopyrite, and chalcopyrite. Colloids consisting of Fe, S, and O with structures resembling framboidal pyrite were identified, which is consistent with the non-silicates minerals identified by XRD. Our study suggests that the physical weathering of pyrite in the mine spoil can generate colloidal pyrite, which is mobilized and transported by soil pore water. Our results also indicate that these pyritic colloids are associated with toxic trace metals including Cu, Mn, and Zn. Colloid mobilization is also impacted by changes in temperature and precipitation, where clay mobilization afer rain events is favored. Further, sudden spikes in aqueous and/or colloidal concentrations may be the result of local heterogeneity within soils developing on mine spoil, indicating that further field-based work is necessary to better characterize pore-scale processes that control aqueous and colloid transport at similar sites to have a better understanding of potential contaminant transport from mine spoil systems.
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•The release and transport of colloidal pyrite can occur in soils developing on historic coal.•Na, Ca, Mg, K, and Si were primarily associated with the aqueous fraction of soil pore water.•Al, Mn, Fe, Cu, and Zn were primarily associated with Fe-rich, including sulfides and secondary oxides.•Temperature and precipitation were linked to variations in colloidal clay transport.
Escalating antibiotic resistance presents a notable worldwide dilemma, pointing a large involvement of general population. The objective of this study was to assess knowledge, attitudes, and ...practices regarding the utilization of antibiotics among Bangladeshi residents.
A cross-sectional study, conducted from January 01 to April 25, 2022, included 1,947 Bangladeshi adults with a history of antibiotic use, via online surveys and face-to-face interviews using a pretested semi-structured questionnaire. Descriptive statistics, Chi-square tests, and multivariate linear regression models were employed.
Mean scores for knowledge, attitudes, and practices were 6.59±1.20, 8.34±1.19, and 12.74±2.59, with correct rates of 73.22%, 92.67%, and 57.91%. Positive predictors for knowledge included being unmarried (β = 0.10, p = 0.001), higher education (College: β = 0.09, p = 0.025; Bachelor: β = 0.22, p<0.001; Master or above: β = 0.14, p<0.001), various professions (student: β = 0.57, p<0.001; housewife: β = 0.33, p<0.001; employee: β = 0.53, p<0.001; businessman: β = 0.31, p<0.001; unemployed: β = 0.15, p<0.001), and residing in semi-urban (β = 0.32, p<0.001) or urban areas (β = 0.15, p<0.001). Positive predictors for attitudes included being married (β = 0.18, p<0.001), specific professions (student: β = 1.06, p<0.001; housewife: β = 0.33, p<0.001; employee: β = 0.86, p<0.001; businessman: β = 0.37, p<0.001; unemployed: β = 0.47, p<0.001), higher SES (Lower-middle: β = 0.22, p<0.001; Middle: β = 0.26, p<0.001), and residing in semi-urban areas (β = 0.18, p<0.001); negative predictors included higher education (College: β = -0.12, p = 0.001; Master or above: β = -0.09, p = 0.008) and being rich (β = -0.13, p<0.001). Positive predictors for practices included being married (β = 0.18, p<0.001), specific professions (student: β = 0.32, p<0.001; employee: β = 0.43, p<0.001; businessman: β = 10, p = 0.034; unemployed: β = 0.11, p = 0.009), and higher SES (Lower-middle: β = 0.14, p = 0.009; Middle: β = 0.38, p<0.001; Higher-middle: β = 0.15, p = 0.008); negative predictors included higher education (College: β = -0.21, p<0.001), being rich (β = -0.12, p<0.001), residing in semi-urban (β = -0.14, p<0.001) or urban areas (β = -0.16, p<0.001).
Participants exhibited adequate knowledge and positive attitudes but lagged behind in proper practice of antibiotic use. Proper initiatives should be tailored to enhance prudent antibiotic use and mitigate the risk of antimicrobial resistance.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Historical coal mining practices have caused various soil and water hazards, particularly through the dumping of mine waste. The primary environmental risk associated with this waste is the leaching ...of toxic metals from dumps of spoil or refuse into the subsurface soil or into nearby water resources. The extent of metal release is controlled via the oxidative dissolution of pyrite and potential re-sequestration through secondary Fe oxides. The characterization of the dominant Fe-bearing phase and the distribution of trace metals associated with these phases was determined via electron microscopy, synchrotron-based X-ray micro-fluorescence (μ-XRF) element and redox mapping from shallow mine soils from an impacted watershed in Appalachian Ohio. The dominant Fe-bearing phases were: (1) unweathered to partially weathered pyrite; (2) pseudomorphic replacement of pyrite with Fe(III) oxides; (3) fine-grained Fe oxide surface coatings; and (4) discrete Fe(III) oxide grains. Thicker secondary coatings and larger particles were sulfate rich, whereas smaller grains and thinner coatings were sulfate poor. The discrete Fe oxide grains exhibited the highest concentrations of Cr, Mn, Ni, and Cu, and sub-grain-scale concentration trends (Mn > Cr > Ni > Cu) were consistent with bulk soil properties. Predicting future metal transport requires an understanding of metal speciation and distribution from the sub-grain scale to the pedon scale.
The release of colloid-bound trace metals from abandoned coal mine spoils can potentially be a significant source of contamination during weathering. We examined the size-dependent enrichment of ...trace metals in mine spoil samples using centrifugation and acid extraction to compare metal loading in the bulk and colloid fractions. A combination of X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and focused ion beam (FIB) sectioning of selected colloids for transmission electron microscopy (TEM) analyses was used to determine the morphology and elemental and mineral composition at the micro- and nanoscales. In contrast to bulk soils, primary Fe-sulfides (up to 11%) and secondary Fe(III)-bearing phases (up to 5%) were a significant portion of the colloid mineralogy. Secondary Fe-(hydro)oxides and (hydroxy)sulfates were enriched with Mn, Ni, Cu, and Zn, and these metals showed stronger correlations with Fe in the colloid fraction (R2 of 0.58, 0.77, 0.94, and 0.81, respectively) than in the bulk fraction (R2 of 0.40, 0.09, 0.84, and 0.62, respectively), indicating that Fe-bearing colloids are likely major trace-metal-bearing phases. The results from this study will help to design better remediation projects for abandoned mine spoils to better account for a potentially underappreciated mode of contaminant transport.
The literature presents a digitized pension system based on a consortium blockchain, with the aim of overcoming existing pension system challenges such as multiparty collaboration, manual ...intervention, high turnaround time, cost transparency, auditability, etc. In addition, the adoption of hyperledger fabric and the introduction of smart contracts aim to transform multi-organizational workflow into a synchronized, automated, modular, and error-free procedure.
Mine spoils (waste that includes fragments of overburden rock and parent rock) are an unavoidable byproduct of coal mining operations. Before the Surface Mining Control and Reclamation Act of 1977, ...mine spoils were generally discarded at the surface, where mine spoils are vulnerable to natural weathering and erosion. Pyrite is a common mineral present in mine spoil. When exposed to surficial conditions, pyrite undergoes an oxidative dissolution that generates acidic run-offs containing high concentrations of Fe (II), S, and toxic trace metals. Following AMD generation Fe(III)-oxyhydroxysulfates Fe(III)-(oxy)hydroxides precipitate depending on the solution pH. The precipitation of secondary Fe-bearing deposits can also sequester toxic metals through coprecipitation or adsorption. The precipitation of Fe(III)-oxyhydroxysulfates takes place at a lower pH (2- 4.5). When solution pH increases through mixing with surface water, pore water, or through the dissolution of carbonate rocks, Fe(III)-(oxy)hydroxide forms. The increase in pH leads to the dissolution or transformation of Fe(III)-oxyhydroxysulfates into Fe(III)-(oxy)hydroxide, which leads to the release of toxic trace metals. To understand the fate and transport of trace metal, it is important to understand the precipitation dynamics of Fe-bearing deposits in mine spoil. Understanding how trace metals are sequestered within the residual fraction in mine spoils (bulk vs. colloids) is also imperative. Colloids are typically smaller than 10 ?m and are dominated by clays, micas, and Fe-oxides. Trace metals associated with colloids can become mobilized by rainfall and transport toxic metals. Therefore, a careful study of the colloidal metal transport is crucial for a holistic understanding of trace metal dynamics at a mine spoil site. In this dissertation, I investigated: (1) the link between the formation of secondary Fe-bearing phases (jarosite, schwertmannite, ferrihydrite, and goethite) and trace metal sequestration; (2) the size-dependent (bulk soil vs. colloids) enrichment of trace metal in mine spoil samples along a transect of increasing elevation; and (3) the mineralogical composition of colloids migrating in porewater and their to base and trace metal transport. A combination of scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), focused ion beam milled samples analyzed by transmission electron microscopy (FIB-TEM), X-ray diffraction (XRD), and synchrotron-based X-ray Microprobe (XMP) analyses was conducted to determine the morphology elemental, and mineral composition and oxidation state of the colloids. Chapter 1 includes the historical background of coal mining in the United States, mine spoil generation, pyrite oxidation, AMD generation, and the dominant factors that control the fate and transport of trace metals in areas impacted by historic coal mining. Chapter 2 reports how trace element (Cr, Mn, Cu, and Ni) partitioning during oxidative pyrite dissolution is controlled in part by whether Fe(III) precipitation occurs immediately (e.g., pseudomorphic replacement of pyrite) or after transport in pore water. The presence of S and the morphology of the deposit were also important factor in controlling trace metal sequestration. Chapter 3 presents research on trace metal enrichment in a colloidal fraction of bulk soil and colloidal trace metal transport. Chapter 4 reports higher trace metal transport in the pore water in the colloidal phase compared to the aqueous phase and colloidal transport of pyrite.
BackgroundEscalating antibiotic resistance presents a notable worldwide dilemma, pointing a large involvement of general population. The objective of this study was to assess knowledge, attitudes, ...and practices regarding the utilization of antibiotics among Bangladeshi residents.MethodsA cross-sectional study, conducted from January 01 to April 25, 2022, included 1,947 Bangladeshi adults with a history of antibiotic use, via online surveys and face-to-face interviews using a pretested semi-structured questionnaire. Descriptive statistics, Chi-square tests, and multivariate linear regression models were employed.ResultsMean scores for knowledge, attitudes, and practices were 6.59±1.20, 8.34±1.19, and 12.74±2.59, with correct rates of 73.22%, 92.67%, and 57.91%. Positive predictors for knowledge included being unmarried (β = 0.10, p = 0.001), higher education (College: β = 0.09, p = 0.025; Bachelor: β = 0.22, p<0.001; Master or above: β = 0.14, p<0.001), various professions (student: β = 0.57, p<0.001; housewife: β = 0.33, p<0.001; employee: β = 0.53, p<0.001; businessman: β = 0.31, p<0.001; unemployed: β = 0.15, p<0.001), and residing in semi-urban (β = 0.32, p<0.001) or urban areas (β = 0.15, p<0.001). Positive predictors for attitudes included being married (β = 0.18, p<0.001), specific professions (student: β = 1.06, p<0.001; housewife: β = 0.33, p<0.001; employee: β = 0.86, p<0.001; businessman: β = 0.37, p<0.001; unemployed: β = 0.47, p<0.001), higher SES (Lower-middle: β = 0.22, p<0.001; Middle: β = 0.26, p<0.001), and residing in semi-urban areas (β = 0.18, p<0.001); negative predictors included higher education (College: β = -0.12, p = 0.001; Master or above: β = -0.09, p = 0.008) and being rich (β = -0.13, p<0.001). Positive predictors for practices included being married (β = 0.18, p<0.001), specific professions (student: β = 0.32, p<0.001; employee: β = 0.43, p<0.001; businessman: β = 10, p = 0.034; unemployed: β = 0.11, p = 0.009), and higher SES (Lower-middle: β = 0.14, p = 0.009; Middle: β = 0.38, p<0.001; Higher-middle: β = 0.15, p = 0.008); negative predictors included higher education (College: β = -0.21, p<0.001), being rich (β = -0.12, p<0.001), residing in semi-urban (β = -0.14, p<0.001) or urban areas (β = -0.16, p<0.001).ConclusionsParticipants exhibited adequate knowledge and positive attitudes but lagged behind in proper practice of antibiotic use. Proper initiatives should be tailored to enhance prudent antibiotic use and mitigate the risk of antimicrobial resistance.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The goal of the study was to evaluate the potential of the V2G system as a solution to peak load leveling and integrating more renewable energy in the microgrid of St. Martine Island. Simulink ...Simscape software was used to model a microgrid with a V2G system for the small community of the Island. The result of the study shows a V2G system with 100 electric cars could play an important role for peak shaving by supplying up to 0.8 MW of electric power back to the grid during peak hours, where each car contributes 10 kW of electric power. It also demonstrates that the V2G system effectively helps to promote solar power capacity from 1 MW to 2.5 MW, hence increase 23.59% share of solar energy in the total grid energy uses compared with the current microgrid of St. Martine Island.
The electricity that is generated from non-renewable sources causesenvironmental pollution and climate changes. Fossil fuel uses leads to thedepletion of fossil fuel resources as well as global warming. On the other hand, renewable energy sources can be used to produce electricity with very few or no CO2 emissions. So, now governments are focusing on renewable energy production. But solar, wind, and other types of renewable energy sources have intermittency. They are not continuously available due to natural factors that cannot be controlled. So, renewable energy needs to be utilized when it is available, or its intermittency can be overcome by energy storage. All Electric vehicle uses a battery pack of large capacity to power the electric motors. These batteries can be used to store the energy that is generated from renewable sources and use them when needed. Besides, the electric grid must always stay in balance. With the development of variable renewable energy production, the management of this balance has become complex. Vehicle to grid is a technology that enables energy to be pushed back to the grid from the battery of an electric car and helps to manage fluctuations on the electricity grid. It helps to balance the grid by charging the battery when renewableenergy is available and load demand is low, then sending energy back to the grid when load demand is high. However, St. Martine Island is a small Island in Bay of Bengal about 9km south of the mainland of Bangladesh. Nearly 6000 people are living there. Since the island is far away from the mainland, grid connection is almostimpossible in terms of cost and geographic location. St. Martine Island has a very high solar power potential, but very low average wind speed. Currently, the electricity demand is fulfilled by stand-alone diesel generators, PV panels, and wind turbines. The current microgrid gets a high load demand during peak hours which is between 6 pm to 11 pm. During this time grid become fully dependent on diesel generators which leads to fossil fuel uses andenvironmental pollution. Here, the project's key objective is to determine the prospects of V2Gtechnology on St. Martine Island to level the peak load during peak hours, given that St. Martine Island is a low windy island with a high average number of yearly peak sun hours. Another goal is to examine the degree to which the share of solar power can be increased by a V2G system in St. Martine Island. In the project, at first, we have modeled a microgrid using Simulink Simscape software. Simulink Simscape enables modeling of a system by putting direct physical connections between the block diagram. In the microgrid model, there are five main sections, which have been designed by assemblingfundamental components in the schematic. A V2G system has been modeled which consists of 100 electric cars as aprototype. Each car has a battery of 100 kWh capacity. Considering thecondition of St. Martine Island and the objective of the project, we have made some assumptions while modeling the V2G section. The results of the project showed that the V2G system significantly smoothed out the peak load during peak hours. It also demonstrated that charging electric cars during daytime by solar power and sending energy back to the grid during peak hours enables the V2G system to accommodate more renewable solar energy sources in the microgrid of St. Martine Island. Finally, the project evident that the V2G system can be integrated into the microgrid of St. Martine Island to level the peak load and to increase the share of solar energy in the total energy uses of the Island.
Helicobacter Pylori a very common worldwide infection is responsible for number of upper GIT lesions like gastritis, peptic ulcer disease, gastric carcinoma and mucosa associated lymphoid tissue ...lymphoma. On the other hand, dyspepsia is a wide spectrum of nonspecific upper GIT symptoms for which patients very frequently visit gastroenterology clinics. The objective of the study was to find prevalence of Helicobacter Pylori among the patients with dyspeptic symptoms who had gastro-duodenal mucosal lesions on upper GIT endoscopy and also if there is any association between these two variables. 164 cases of dyspepsia were done index upper GIT endoscopy as per inclusion and exclusion criteria from April 2018 to December 2018 in Seikh Sayera Khatun Medical College Hospital, Gopalganj. Two gastric biopsies (from antrum and body) were taken and immediately placed in a commercial RUT (rapid urease test) kit. Positive test (rapid urease test) was indicated by change in the color of the kit from yellow to pink or red within 24 hours. Out of 164 patients, 62 (37.8%) patients had gastro-duodenal mucosal lesions and rest(62.2%) showed normal upper GIT at endoscopy. Among the 62 patients highest (38) number of the patients endoscopy showed gastritis and least (3) showed gastric ulcer. Among 62 patients with endoscopic gastro-duodenal mucosal lesions, 36 patients were infected with Helicobacter Pylori. On the contrary 27 patients out of 102 subjects who had normal upper GIT at endoscopy recorded infected with Helicobacter Pylori. Statistically analysis was done using chi-square test with the help of SPSS software windows version 25. The level of statistical significance was set at 0.05. In our study it was observed that statistically there was significant relation of Helicobacter Pylori with gastro-duodenal mucosal lesions as P value was less than 0.05. In this study, we found that Helicobacter Pylori was significantly associated with gastro-duodenal mucosal lesions among the patients with dyspeptic symptoms. So, our suggestion will be to confirm H. pylori infection if anybody has gastro-duodenal mucosal lesions if a subject does upper GIT endoscopy for dyspeptic symptoms.
J Dhaka Medical College, Vol. 28, No.1, April, 2019, Page 100-104
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