Geochemical and petrological studies of high sulfur coal and overburden from Makum coalfield (Northeast India) towards understanding and mitigation of acid mine drainage

Opencast coal mining produces trash of soil and rock containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage(AMD)through oxidation pyrite minerals.The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India.In order to have a comprehensive overview of the AMD problem in Makum coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Makum coalfield(Northeast India)were thoroughly investigated.The maceral compositions reveal that coal features all three groups of macerals(liptinite,vitrinite,and inertinite),with a high concentration of liptinite indicating the coal of perhydrous,thereby rendering it more reactive.Pyrite(FeS_(2))oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and(OB)samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods,and to replicate the actual mine site leaching.Inductively coupled plasma-optical emission spectroscopy(ICP-OES)was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment.The Rare earth element(REE)enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB.These experiments reveal the change in conductivity,acid producing tendency,total dissolved solid(TDS),total Iron(Fe)and dissolved Sulfate(SO_(4)^(2−))ions on progress of the leaching experiments.Moreover,the discharge of FeS_(2) via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics.A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station.Apart from neutralisation of AMD water,this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water.

Comparative measurement of CO_(2),CH_(4)and CO at two traffic interjunctions having inflated vehicular flow in Delhi

Vehicular emissions are considered one of the major anthropogenic sources of greenhouse gases and poor air quality in metropolitan cities.This study aims to see the correlation of CO_(2),CH_(4),and CO through monitoring over a period from December 2020 to October 2021 covering three seasons’winter,summer,and monsoon at two different traffic locations of Delhi having different traffic volumes,road patterns,and traffic management.The annual average morning concentration of CO_(2),CH_(4)and CO was found(533±105),(7.3±3.1),(10.7±3.0)ppm at Najafgarh and(480±70),(5.2±1.8),(7.8±2.8)ppm at Rajendra Place,respectively.A relationship between concentration of all three gases and meteorological parameters such as temperature,humidity,wind speed and wind direction has also been investigated using Pearson correlation coefficient and pollution rose diagram.A comparable pattern in concentration was observed for all three gases in spatial(location)and temporal(diurnal)distribution.The concentration trend of CO_(2)in different seasons is winter>summer>monsoon,while in the case of CH_(4)winter=summer>monsoon but not any seasonal trend was noted in CO case.It is observed that CO_(2)has a good relation with CO(a tracer for vehicular emission)in terms of diurnal variation,whereas,CH_(4)does not represent a relation with CO and CO_(2)diurnally,suggesting that vehicles are the source of CO_(2)but not much contributing to other greenhouse gases like CH_(4).

Transition metal-based single-atom catalysts(TM-SACs);rising materials for electrochemical CO_(2) reduction

The continuous increase of global atmospheric CO_(2) concentrations brutally damages our environment. A series of methods have been developed to convert CO_(2) to valuable fuels and value-added chemicals to maintain the equilibrium of carbon cycles. The electrochemical CO_(2) reduction reaction(CO_(2)RR) is one of the promising methods to produce fuels and chemicals, and it could offer sustainable paths to decrease carbon intensity and support renewable energy. Thus, significant research efforts and highly efficient catalysts are essential for converting CO_(2) into other valuable chemicals and fuels. Transition metal-based single atoms catalysts(TM-SACs) have recently received much attention and offer outstanding electrochemical applications with high activity and selectivity opportunities. By taking advantage of both heterogeneous and homogeneous catalysts, TM-SACs are the new rising star for electrochemical conversion of CO_(2) to the value-added product with high selectivity. In recent years, enormous research effort has been made to synthesize different TM-SACs with different M–Nxsites and study the electrochemical conversion of CO_(2) to CO. This review has discussed the development and characterization of different TMSACs with various catalytic sites, fundamental understanding of the electrochemical process in CO_(2) RR,intrinsic catalytic activity, and molecular strategics of SACs responsible for CO_(2)RR. Furthermore, we extensively review previous studies on 1 st-row transition metals TM-SACs(Ni, Co, Fe, Cu, Zn, Sn) and dual-atom catalysts(DACs) utilized for electrochemical CO_(2) conversions and highlight the opportunities and challenges.

In vitro and in vivo anticancer potential and molecular targets of the new colchicine analog ⅢM-067

Objective: The current study evaluated various new colchicine analogs for their anticancer activity and to study the primary mechanism of apoptosis and in vivo antitumor activity of the analogs with selective anticancer properties and minimal toxicity to normal cells.Methods: Sulforhodamine B(SRB) assay was used to screen various colchicine analogs for their in vitro cytotoxicity. The effect of N-[(7S)-1,2,3-trimethoxy-9-oxo-10-(pyrrolidine-1-yl)5,6,7,9-tetrahydrobenzo[a] heptalene-7-yl] acetamide(ⅢM-067) on clonogenicity, apoptotic induction, and invasiveness of A549 cells was determined using a clonogenic assay, scratch assay, and staining with 4’,6-diamidino-2-phenylindole(DAPI) and annexin V/propidium iodide. Mitochondrial membrane potential(MMP) and reactive oxygen species(ROS) levels were observed using fluorescence microscopy. Western blot analysis was used to quantify expression of proteins involved in apoptosis, cell cycle, and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian target of rapamycin(mTOR) signaling. Pharmacokinetic and in vivo efficacy studies against Ehrlich ascites carcinoma(EAC) and Ehrlich solid tumor models were conducted using Swiss albino mice.Results: ⅢM-067 showed potent cytotoxicity and better selectivity than all other colchicine analogs screened in this study. The selective activity of ⅢM-067 toward A549 cells was higher among other cancer cell lines,with a selectivity index(SI) value of 2.28. ⅢM-067 demonstrated concentration-and time-dependent cytotoxicity against A549 cells with half-maximal inhibitory concentration values of 0.207, 0.150 and0.106 μmol/L at 24, 48 and 72 h, respectively. It also had reduced toxicity to normal cells(SI > 1) than the parent compound colchicine(SI = 1). ⅢM-067 reduced the clonogenic ability of A549 cells in a dose-dependent manner. ⅢM-067 enhanced ROS production from 24.6% at 0.05 μmol/L to 82.1% at 0.4 μmol/L and substantially decreased the MMP(100% in control to 5.6% at 0.4 μmol/L). The annexin V-FITC assay demonstrated78% apoptosis at 0.4 μmol/L. ⅢM-067 significantly(P < 0.5) induced the expression of various intrinsic apoptotic pathway proteins, and it differentially regulated the PI3K/AKT/mTOR signaling pathway. Furthermore,ⅢM-067 exhibited remarkable in vivo anticancer activity against the murine EAC model, with tumor growth inhibition(TGI) of 67.0% at a dose of 6 mg/kg(i.p.) and a reduced mortality compared to colchicine. ⅢM-067also effectively inhibited the tumor growth in the murine solid tumor model with TGI rates of 48.10%, 55.68%and 44.00% at doses of 5 mg/kg(i.p.), 6 mg/kg(i.p.) and 7 mg/kg(p.o.), respectively.Conclusion: ⅢM-067 exhibited significant anticancer activity with reduced toxicity both in vitro and in vivo and is a promising anticancer candidate. However, further studies are required in clinical settings to fully understand its potential.

Enhanced thermoelectric performance of Bi_(0.5)Sb_(1.5)Te_(3) via Ni-doping:A Shift of peak ZT at elevated temperature via suppressing intrinsic excitation

Bi_(2)Te_(3)-based thermoelectric(TE)materials have been demonstrated to be a potential candidate for mainly thermoelectric cooling/refrigeration applications.However,minority charge carriers excitation at high temperature reduces thermopower which restricts these materials for the use in power generation.In present work,substitution of Ni on Sb site in Bi_(0.5)Sb_(1.5-x)NixTe_(3)(x=0,0.01,0.04 and 0.08)actuates the system to supress the intrinsic excitation leading to shift in highest ZT to higher temperature regime.The Density functional theory(DFT)calculations and experimental results reveal that Ni in Bi_(0.5)Sb_(1.5)Te3 provides the extra holes and slightly reduces the band gap Eg which enhances the s of Ni-doped Bi_(0.5)Sb_(1.5-x)NixTe_(3) samples and a at elevated temperature.Moreover,Ni-doping in Bi_(0.5)Sb_(1.5)Te_(3) also reduces kL which is attributed to the phonon scattering due to mass fluctuations and microstructural features such as grain boundary and strain field domain observed from HRTEM investigation.These favourable condition leads to maximum ZT~1.38 at 433K for Bi_(0.5)Sb_(1.46)Ni_(0.04)Te_(3) and ZT_(avg)~1.1 between 300K and 503K.Interestingly the calculated theoretical TE conversion device efficiency h of Bi_(0.5)Sb_(1.46)Ni_(0.04)Te3(η~5.5%)was achieved to be nearly twice than the efficiency of matrix Bi_(0.5)Sb_(1.5)Te3(h~3%).Experimental electronic transport is well corroborated with theoretically estimated DFT results.

Enhanced thermoelectric performance in p-type ZrCoSb based half-Heusler alloys employing nanostructuring and compositional modulation

ZrCoSb based half-Heusler(HH)alloys have been widely studied as a p-type thermoelectric(TE)material for power generation applications in the mid-temperature regime.However,their intrinsically high thermal conductivity has been found to be detrimental for the improvement in their thermoelectric figure-of-merit(ZT),which presently is far below unity.In the current work,a state-of-the-art ZT~1.1 at 873 K was realized in an optimized composition of nanostructured Zr1-xHfxCoSb_(0.9)Sn_(0.1) HH alloys by employing compositional modulation i.e.grain-by-grain compositional variations,which leads to a substantial increase in its power factor coupled with a concurrent decrease in its thermal conductivity.Significant reduction in the phonon mean-free-path is observed on Hf substitution,which is comparable to the average crystallite size(~25 nm),thus leading to a very low thermal conductivity of~2.2Wm^(-1)K^(-1) at 873 K,which is amongst the lowest reported in HH alloys.The TE device characteristics,estimated using cumulative temperature dependence model for quantitative evaluation of TE performance,yielded an output power density of~10 Wcm
2 with a leg efficiency of~10%in the optimized composition of nanostructured Zr_(1-x)Hf_(x)CoSb_(0.9)Sn_(0.1) HH alloys,which is comparable to the reported efficiencies of other state-of-the-art TE materials.