Low-Abundance Members of the Firmicutes Facilitate Bioremediation of Soil Impacted by Highly Acidic Mine Drainage From the Malanjkhand Copper Project, India

Sulfate- and iron-reducing heterotrophic bacteria represented minor proportion of the indigenous microbial community of highly acidic, oligotrophic acid mine drainage (AMD), but they can be successfully stimulated for in situ bioremediation of an AMD impacted soil (AIS). These anaerobic microorganisms although played central role in sulfate- and metal-removal, they remained inactive in the AIS due to the paucity of organic carbon and extreme acidity of the local environment. The present study investigated the scope for increasing the abundance and activity of inhabitant sulfate- and iron-reducing bacterial populations of an AIS from Malanjkhand Copper Project. An AIS of pH 3.5, high soluble SO42− (7838 mg/l) and Fe (179 mg/l) content was amended with nutrients (cysteine and lactate). Thorough geochemical analysis, 16S rRNA gene amplicon sequencing and qPCR highlighted the intrinsic metabolic abilities of native bacteria in AMD bioremediation. Following 180 days incubation, the nutrient amended AIS showed marked increase in pH (to 6.6) and reduction in soluble -SO42− (95%), -Fe (50%) and other heavy metals. Concomitant to physicochemical changes a vivid shift in microbial community composition was observed. Members of the Firmicutes present as a minor group (1.5% of total community) in AIS emerged as the single most abundant taxon (∼56%) following nutrient amendments. Organisms affiliated to Clostridiaceae, Peptococcaceae, Veillonellaceae, Christensenellaceae, Lachnospiraceae, Bacillaceae, etc. known for their fermentative, iron and sulfate reducing abilities were prevailed in the amended samples. qPCR data corroborated with this change and further revealed an increase in abundance of dissimilatory sulfite reductase gene (dsrB) and specific bacterial taxa. Involvement of these enhanced populations in reductive processes was validated by further enrichments and growth in sulfate- and iron-reducing media. Amplicon sequencing of these enrichments confirmed growth of Firmicutes members and proved their sulfate- and iron-reduction abilities. This study provided a better insight on ecological perspective of Firmicutes members within the AMD impacted sites, particularly their involvement in sulfate- and iron-reduction processes, in situ pH management and bioremediation

Recent development of alkali metal complex promoted iso-selective ring opening polymerization of rac-Lactide

Polyesters especially polylactide (PLA) are one of the most important and extensively studied biodegradable polymers for their use in medicine, agriculture, packaging, and drug delivery. Importantly, these polymers can be formed by the ring opening polymerization (ROP) of lactide by carefully designed metal complexes that can act as catalysts for such reactions have emerged as useful tools to achieve this goal. In recent years, alkali metal-based organometallic complexes have appeared as an alternative to transition metal and rare earth metals catalysts for the ROP of rac-LA systems. This strategy is advantageous because it obviates the need for pre-generated toxic metal precursors. This review highlights the progress of alkali metal-based catalysis for the ROP of rac-LA that come out with a critical assessment of the futuristic research, spotlight the major developments achieved in the past few years, and provides an overview of the challenges and opportunities

Alkali and Alkaline Earth Metal Complexes as Versatile Catalysts for Ring‐Opening Polymerization of Cyclic Esters

Biodegradable polyesters such as poly(ϵ-caprolactone) (PCL) and poly(lactic acid) (PLA) have been considered for use in several areas, such as drug delivery devices, sutures, tissue engineering, and GBR membranes, due to its bio-renewability, biodegradability, and biocompatibility. Several synthetic techniques for the preparation of polyesters have been reported in the literature, amongst which the ring-opening polymerization (ROP) of cyclic esters is the most efficient. A convenient approach to access iso-selective PLAs is polymerization of racemic lactide (rac-LA), which shows excellent stereoregularity without the need for costly chiral auxiliaries or ligands. In this personal account, we review a series of methods that have been practiced to the synthesis of biodegradable polyesters from various cyclic monomers using alkali and alkaline earth metal complexes as efficient catalysts

Alkali Metal Complex–Mediated Ring-opening Polymerization of rac-LA, ε-Caprolactone, and δ-Valerolactone

A series of alkali metal complexes formed by N-(2-fluoro/2-nitro phenyl)-P,P-diphenylphosphinoselenoic amide [(Ph2P(Se)NH(2-RC4H4)] [R = F (1-H); NO2 (2-H)] ligands with molecular formulas [M(THF)2(Ph2P(Se)N(2-RC4H4)] [M = Li, R = F (3a), NO2 (3b)] and [M(THF)2(Ph2P(Se)N(2-RC4H4)] [M = Na, R = F (4a), NO2 (4b); M = K, R = F (5a), NO2 (5b)] have been synthesized in great yield and fully characterized. The molecular structures of protic-ligands 1-H and 2-H, and alkali metal complexes 3b, 4a, and 4b were analyzed using single-crystal X-ray diffraction analysis. Sodium and potassium complexes 4a,b and 5a,b were proved to be active catalysts for the ring-opening polymerization (ROP) of rac-LA (rac-LA), ε-caprolactone, and δ-valerolactone at room temperature only. The best isoselectivity of poly(lactide) (PLA) was achieved to a high value of Pi = 0.78 using sodium complex 4b. One exceedingly dynamic potassium complex (5a,5b) even can catalyze the polymerization of 1,000 counterparts of rac-LA and yield polylactide with a high molecular weight and narrow polydispersity record (PDI). Experimental outcomes also showed steric hindrance, and electronic impacts have noteworthy consequences for this catalysis in the ROP of rac-LA

Characterization of interface bond of ultra-high-performance concrete bridge deck overlays

Critical components of the nation\u27s bridge network, concrete bridge decks, are deteriorating at a rapid rate. This deterioration can be attributed to several factors; however, winter salt application, the diffusion of chlorides to the reinforcing steel, and eventual corrosion of the reinforcement are primary culprits. Multiple protection solutions, include concrete protective systems, sealers, additional cover to the reinforcement, membranes, and epoxy-coated reinforcement, but each solution has shortcomings and does not completely address the problem. Ultra-high-performance concrete, a relatively new material with exceptional strength and durability characteristics, may be a solution to these problems when it is used as a thin overlay on bridge decks. An experimental study was performed to evaluate the bond strength between an ultra-high-performance concrete overlay and a normal concrete substrate with different types of surface textures, including smooth, low roughness, and high roughness. Slant shear and splitting prism tests were performed to quantify the bond strength under compression combined with shear and under indirect tension. Test results demonstrated that under compressive loading, the bond strength was greater than the strength of the substrate when the surface texture was greater than the standard smooth finished mortar surface. For the bond strength under indirect tension, results were not highly sensitive to the surface roughness. In both cases, the measured bond strengths fell within the ranges specified in the American Concrete Institute\u27s Guide for the Selection of Materials for the Repair of Concrete

Comparison of Attendance of Patients Pre-lockdown and during Lockdown in Gynaecology and Antenatal Outpatient Department in a Tertiary Care Hospital of Nadia, West Bengal, India

Introduction: The Coronavirus Disease 2019 (COVID-19) pandemic has brought about a paramount change in the life. This has lead to a reduction in the number of routine patients visiting the Outpatient Department (OPD) of various hospitals and this department was no exception. Aim: To compare the attendance of patient in Antenatal Care (ANC) and Gynaecology Out Patient Department (GOPD) between pre-lockdown and lockdown period due to COVID-19 pandemic. Materials and Methods: The study was conducted among patients attending the OPD in ANC and Gynaecology for 70 days lockdown from 23rd March to 31st May and 70 days immediate pre-lockdown period from 12th January to 22nd March 2020. Daily attendance was noted and types of patient attending in different sub clinics in Gynaecology OPD compared. Enrolment of new ANC patient and old booked cases was compared during both periods. Descriptive statistics were used and displayed as percentages. Results: There was a significant reduction in number of patients attending OPD in lockdown period. There was a total of 6088 (87.3%) reduction in number of patients in Gynaecology OPD and 2235 (69.6%) reduction of patients in ANC OPD which was found to be significant with p-value <0.001. Reduction of patient in lockdown days among new ANC was 574 while it was 1661 in case of old patients. The different sub clinics of GOPD like infertility (704), endocrine (1450), uro-gynaecology (656), STD/ PID (732), postpartum (597), cancer detection (316), abortion and medical termination of pregnancy (MTP) (330), others (1303) also witnessed a diminution of attendance. Conclusion: COVID-19 caused a significant decrease in footfall of patients in outpatient department due to lockdown, though the percentage of types of patient attending Gynaecology OPD was almost same

Metagenomic exploration of microbial community in mine tailings of Malanjkhand copper project, India

Mine tailings from copper mines are considered as one of the sources of highly hazardous acid mine drainage (AMD) due to bio-oxidation of its sulfidic constituents. This study was designed to understand microbial community composition and potential for acid generation using samples from mine tailings of Malanjkhand copper project (MCP), India through 16S rRNA gene based amplicon sequencing approach (targeting V4 region). Three tailings samples (T1, T2 and T3) with varied physiochemical properties selected for the study revealed distinct microbial assemblages. Sample (T3) with most extreme nature (pH 3.0) exhibited abundance of Proteobacteria, Fimicutes, Actinobacteria and/or Nitrospirae. Metagenomic sequences are available under the BioProject ID PRJNA361456

Influence of Exteriorised versus Intra-abdominal Uterine Repair Caesarean Delivery under Spinal Anaesthesia on Intraoperative and Postoperative Complications

Introduction: Caesarean techniques have evolved over time to increase their safety. Intra-abdominal closure of uterine incision seems more physiological. Exteriorisation makes repair easier with a better exposure. But this causes tension to the supporting structures attached to uterus and stretching of vasculature with the risk of intraoperative haematoma or aneurysm later on. Aim: To compare the in-situ repair Group and exteriorised repair group caesarean delivery under spinal anaesthesia regarding occurrence of intraoperative and postoperative complications of interest. Materials and Methods: A prospective interventional study was conducted in the Department of Obstetrics and Gynaecology at College of Medicine and Jawaharlal Nehru Memorial Hospital, West Bengal, India, over a period of two years from April 2014 to March 2016. Four hundred women undergoing caesarean section who fulfilled the inclusion and exclusion criteria were recruited in the study. They were randomly allocated into two study groups as per a computer generated random allocation table. In Group A (n=200) uterine incision was closed after uterus was exteriorised and in Group B (n=200) uterine incision was closed keeping it inside the abdomen. Intraoperative and postoperative parameters of interest such as nausea-vomiting, drop in pulse rate, incision closure time, drop in haemoglobin, blood transfusion rate, return of bowel sounds, febrile morbidity, surgical site infection, hospital stay etc., were noted and compared between the two groups. Numerical variables were expressed as mean and standard deviation and analysed using independent sample t-test. For qualitative variables frequency and percentage were calculated and analysed using Chi-square. Collected data was transferred and analysed using Statistical Package for Social Sciences (SPSS) version25. The p-value ≤0.05 was considered significant. Results: The demographic profiles like age, parity, gestational age etc. of both the groups were similar. There was a significant difference in uterine closure time (9±2.5 minutes in in-situ repair group vs. 10±2 minutes in exteriorisation and repair groups, respectively (p0.05). Mean drop of haemoglobin was more in the intraabdominal closure group (1.5±1.3 gm/dL) as compared to the group of closure after exteriorisation (1.4±1.3 gm/dL) though the difference was not significant statistically (p=0.44). Postpartum blood transfusion rate was 6.5% in exteriorised repair group and 9% in in-situ repair group (p=0.35). Postoperative morbidity like fever, surgical site infection, length of hospital stay was similar in both the groups. Conclusion: Choice of uterine closure method is operator dependent and either method of uterine closure is acceptable when practiced and skill is gained. Exteriorisation is advantageous when excessive bleeding is encountered. Though time taken for closure in in-situ group is statistically more it is similar practically. Bowel sounds returned earlier postoperatively in in-situ group