Antiferromagnetically ordered topological semimetals in Hubbard model with spin-orbit coupling.

We examine the possible existence of Dirac semimetal with magnetic order in a two-dimensional system with a nonsymmorphic symmetry by using the Hartree-Fock mean-field theory within the Hubbard model. We locate the region in the second-neighbor spin-orbit coupling vs Hubbard interaction phase diagram, where such a state is stabilized. The edge states for the ribbons along two orthogonal directions concerning the orientation of in-plane magnetic moments are obtained. Finally, the effect of the in-plane magnetic field, which results in the stabilization of the Weyl semimetallic (WSM) state, and the nature of the edge states corresponding to the WSM state for ribbon geometries are also explored.

Spin-orbit coupling and magnetism inSr2CrO4.

With one electron in the degenerateyz,xzorbital sector, theSr2CrO4compound exhibits active orbital degree of freedom, resulting in strongly enhanced orbital and spin-orbital correlations due to Coulomb interaction induced renormalization of the otherwise weak bare spin-orbit coupling (SOC) in this 3dtransition metal compound. Finite temperature orbital fluctuations strongly reduce spin-orbital correlations, effective SOC strength, and magnon excitation energy. Orbital and magnetic transition temperatures estimated from the calculated orbiton and (renormalized) magnon energies are in good agreement with the experimental values obtained from susceptibility and resistivity anomalies in recent high-pressure studies.

Non-Linear Kinetics of The Lithium Metal Anode on Li6 PS5 Cl at High Current Density: Dendrite Growth and the Role of Lithium Microstructure on Creep.

Interfacial instability, viz., pore formation in the lithium metal anode (LMA) during discharge leading to high impedance, current focusing induced solid-electrolyte (SE) fracture during charging, and formation/behaviour of the solid-electrolyte interphase (SEI), at the anode, is one of the major hurdles in the development of solid-state batteries (SSBs). Also, understanding cell polarization behaviour at high current density is critical to achieving the goal of fast-charging battery and electric vehicle. Herein, via in situ electrochemical scanning electron microscopy (SEM) measurements, performed with freshly deposited lithium microelectrodes on transgranularly fractured fresh Li6PS5Cl (LPSCl), the LiǀLPSCl interface kinetics are investigated beyond the linear regime. Even at relatively small overvoltages of a few mV, the LiǀLPSCl interface shows non-linear kinetics. The interface kinetics possibly involve multiple rate-limiting processes, i.e., ion transport across the SEI and SE|SEI interfaces, as well as charge transfer across the LiǀSEI interface. The total polarization resistance RP of the microelectrode interface is determined to be ≈ 0.8 Ω cm2 . It is further shown that the nanocrystalline lithium microstructure can lead to a stable LiǀSE interface via Coble creep along with uniform stripping. Also, spatially resolved lithium deposition, i.e., at grain surface flaws, grain boundaries, and flaw-free surfaces, indicates exceptionally high mechanical endurance of flaw-free surfaces toward cathodic load (>150 mA cm-2 ). This highlights the prominent role of surface defects in dendrite growth.

Semimetallic spin-density wave state in iron pnictides.

We examine the existence of semimetallic spin-density wave (SDW) states in iron pnictides. In the experimentally observed metallic SDW state, the symmetry-protected Dirac cones are located away from the Fermi surface giving rise to tiny pockets and there are also additional Fermi pockets such as one around Γ. We find that the location of a pair of Dirac points with respect to the Fermi surface exhibits significant sensitivity to the orbital splitting between thedxzanddyzorbitals. Besides, in the presence of orbital splitting, the Fermi pockets not associated with the Dirac cones, can be suppressed so that a semimetallic SDW state can be realized. We explain these findings in terms of difference in the slopes and orbital contents of the bands which form the Dirac cone, and obtain the necessary conditions dependent on these two and other parameters for the coexisting Dirac semimetallic and SDW states. Additionally, the topologically protected edge states are studied in the ribbon geometry when the same are oriented either alongxoryaxes.

Effect of isopropyl side chain branching and different anions on electronic structure, vibrational spectra, and hydrogen bonding of isopropyl-imidazolium-based ionic liquids: Experimental and theoretical investigations.

In the present work, four branched methylated, 1,2-dimethyl-3-isopropyl-imidazolium (i-[C3Dmim+]) and protonated,1-methyl-3-isopropyl-imidazolium (i-[C3mim+])-based ionic liquids (ILs) with varying anion (Br-, BF4-, PF6-, and NTf2-) were synthesized and investigated by NMR, infrared (IR) and Raman spectroscopy. Based on infrared and Raman spectroscopy, complete vibrational assignments have been performed. The IR and Raman analysis revealed that the vibrational spectra are virtually unaffected upon methylation, while significant frequency changes were observed by changing anion. Furthermore, to determine the electronic structure, energetic stability, and vibrational properties of these i-[C3Dmim]Y, i-[C3mim]Y (Y = Br, BF4, PF6, and NTf2) ion pairs, quantum chemical calculations including the dispersion correction method are performed both on single ions and on ionic couples. The calculated electron density was analyzed to expose non-covalent intra- and interionic interactions by the quantum theory of atoms in molecules (AIM) and interpreted in terms of both anion dependence and type of interaction. Computational results suggest that for all ionic couples the most energetically stable configuration is obtained with the anions located close to the C2 position of the imidazolium cation. However, in the case of i-[C3mim]NTf2 and i-[C3Dmim]BF4, similar energies were obtained in configurations 2 and 3 where the anion is located above the imidazolium ring. For i-[C3mim]Br a stronger hydrogen bond is predicted than for other studied ILs. Calculations indicate that a red shift of the CH stretching bands should occur due to hydrogen bonding; indeed, such displacement of bands is experimentally observed.

Mce1R of Mycobacterium tuberculosis prefers long-chain fatty acids as specific ligands: a computational study.

The mce1 operon of Mycobacterium tuberculosis, which codes the Mce1 transporter, facilitates the transport of fatty acids. Fatty acids are one of the major sources for carbon and energy for the pathogen during its intracellular survival and pathogenicity. The mce1 operon is transcriptionally regulated by Mce1R, a VanR-type regulator, which could bind specific ligands and control the expression of the mce1 operon accordingly. This work reports computational identification of Mce1R-specific ligands. Initially by employing cavity similarity search algorithm by the ProBis server, the cavities of the proteins similar to that of Mce1R and the bound ligands were identified from which fatty acids were selected as the potential ligands. From the earlier-generated monomeric structure, the dimeric structure of Mce1R was then modeled by the GalaxyHomomer server and validated computationally to use in molecular docking and molecular dynamics simulation analysis. The fatty acid ligands were found to dock within the cavity of Mce1R and the docked complexes were subjected to molecular dynamics simulation to explore their stabilities and other dynamic properties. The data suggest that Mce1R preferably binds to long-chain fatty acids and undergoes distinct structural changes upon binding.

Spin-orbit coupling, orbitally entangled antiferromagnetic order, and collective spin-orbital excitations inSr2VO4.

With electron fillingn = 1 in theSr2VO4compound, the octahedrally coordinatedt2gorbitals are strongly active when the tetragonal distortion induced crystal field is tuned by external agent such as pressure. Considering the full range of crystal field induced tetragonal splitting in a realistic three-orbital model, collective spin-orbital excitations are investigated using the generalized self-consistent plus fluctuation approach. At ambient pressure, an entangled orbital + antiferromagnetic order is found to be stabilized beyond a critical value (∼30 meV) of spin-orbit coupling which is in the realistic range for 3d ions. The behavior of the calculated energy scales of collective excitations with crystal field is consistent with that of the transition temperatures with pressure as obtained from susceptibility and resistivity anomalies in high-pressure studies.

Decreasing toxicity and increasing photoconversion efficiency by Sn-substitution of Pb in 5-ammonium valeric acid-based two-dimensional hybrid perovskite materials.

The toxicity of Pb in halide-based hybrid perovskite materials stands in the way of their more extensive use, despite their excellent optical properties, high stability and very good photoconversion efficiency. The presented work focuses on addressing the toxicity issues in 2D perovskites. We use 5-ammonium valeric acid (AVA) as an organic spacer and partially or completely eliminate Pb by Sn and apply first principles-based density functional theory (DFT) calculations to determine the properties of these systems. Structural insights are gained, which predict the major changes in the inorganic framework including the metal-halide bond length and the bridging angle between two octahedral configurations. The replacement of Pb by Sn leads to a drastic reduction of the electronic band gap from 1.84 to 1.04 eV. Increasing the Sn content results in Sn-I bonds being stronger than the Pb-I bonds, which entails strong s-p coupling. The calculated effective masses of excitons decrease by up to ∼23% in the case of lead-free perovskites, which can be attributed to the more dispersive band edges due to stronger s-p coupling. The reduction of the effective masses of the charge carriers and the electronic band gap results in high electrical conductivity for the AVA2(MA)Sn2I7 2D perovskite structure. The three structures compared, where AVA2(MA)XI7 (X = Pb2, PbSn, Sn2) exhibit excellent thermoelectric power factors, which suggests promising applications for heat energy conversion. Moving toward lead-free 2D perovskites, the real part of the dielectric constants enhances, which may limit the radiative recombination of charge carriers. Furthermore, reducing the bandgap values by the substitution of Sn results in a red-shift in the edge of the absorption coefficients. Using the spectroscopic limited maximum efficiency (SLME) model, the best efficiencies of 32.20 and 30.08% are achieved for the AVA2(MA)PbSnI7 and AVA2(MA)Sn2I7 structures. The comparison of all three structures demonstrates that lead-free 2D perovskites are very good candidates for highly efficient solar energy conversion.

Glucose-induced self-assembly and phase separation in hydrophilic triblock copolymers and the governing mechanism.

Poly(ethylene oxide, EO)-poly(propylene oxide, PO)-poly(ethylene oxide, EO)-based triblock copolymers (BCPs) with 80% hydrophilicity stay molecularly dissolved as Gaussian chains at ambient temperature, even at fairly high concentrations (>5 %w/v). This study presents the plausible micellization behaviour of such very-hydrophilic Pluronics® - F38, F68, F88, F98, and F108 - incited upon the addition of glucose at low concentrations and temperatures. The outcomes obtained from phase behaviour and scattering studies are described. At temperatures near to ambient temperature, these BCPs form micelles with a central core made of a PO block, surrounded by a corona of highly hydrated EO chains. The phase transitions in these hydrophilic Pluronics® in the presence of glucose are demonstrated via the dehydration of the copolymer coil, leading to a decrease in the I1/I3 ratio, as determined using fluorescence spectroscopy. The temperature-dependent cloud point (CP) showed a marked decrease with an increase in the PO molecular weight and also in the presence of glucose. The change in solution relative viscosity (ηrel) caused by glucose is due to the enhanced dehydration of the EO block of the BCP amphiphile. Dynamic light scattering (DLS) and small-angle neutron scattering (SANS) investigations suggested that the dimensions of the hydrophobic core increase during the dehydration of the EO-PO blocks upon a temperature increase or after adding varying concentrations of glucose, thereby resulting in a micellar shape transition. It has been observed that added glucose influences the phase behaviour of BCPs in an analogous way to the influence of temperature. Also, plausible interactions between the EO-PO blocks and glucose were suggested based on the evaluated optimized descriptors obtained from a computational simulation approach. In addition, the core-shell blended micelles obtained using these BCPs are successfully utilized for drug (curcumin, Cur) solubilization based on the observed peak intensities from UV-visible spectroscopy. The loading of Cur into glucose-containing and glucose-free hydrophilic Pluronic® micelles shows how the radius of the micellar core (Rc) increases in the presence of glucose, thereby indicating Cur solubility enhancement for the Pluronic® micelles. Various kinetics models were employed, demonstrating a drug release profile that enables this approach to be used as an ideal platform for drug delivery.

Strong-field ionization of CH3Cl: proton migration and association.

Strong-field ionization of CH3Cl using femtosecond laser pulses, and the subsequent two-body dissociation of CH3Cl2+ along Hn+ (n = 1-3) and HCl+ forming pathways, have been experimentally studied in a home-built COLTRIMS (cold target recoil ion momentum spectrometer) setup. The single ionization rate of CH3Cl was obtained experimentally by varying the laser intensity from 1.6 × 1013 W cm-2 to 2.4 × 1014 W cm-2 and fitted with the rate obtained using the MO-ADK model. Additionally, the yield of Hn+ ions resulting from the dissociation of all charge states of CH3Cl was determined as a function of intensity and pulse duration (and chirp). Next, we identified four two-body breakup pathways of CH3Cl2+, which are H+ + CH2Cl+, H2+ + CHCl+, H3+ + CCl+, and CH2+ + HCl+, using photoion-photoion coincidence. The yields of the four pathways were found to decrease on increasing the intensity from I = 4.2 × 1013 W cm-2 to 2I = 8.5 × 1013 W cm-2, which was attributed to enhanced ionization of the dication before it can dissociate. As a function of pulse duration (and chirp), the Hn+ forming pathways were suppressed, while the HCl+ forming pathway was enhanced. To understand the excited state dynamics of the CH3Cl dication, which controls the outcome of dissociation, we obtained the total kinetic energy release distributions of the pathways and the two-dimensional coincidence momentum images and angular distributions of the fragments. We inferred that the Hn+ forming pathways originate from the dissociation of CH3Cl dications from weakly attractive metastable excited states having a long dissociation time, while for the HCl+ forming pathway, the dication dissociates from repulsive states and therefore, undergoes rapid dissociation. Finally, quantum chemical calculations have been performed to understand the intramolecular proton migration and dissociation of the CH3Cl dication along the pathways mentioned above. Our study explains the mechanism of Hn+ and HCl+ formation and confirms that intensity and pulse duration can serve as parameters to influence the excited state dynamics and hence, the outcome of the two-body dissociation of CH3Cl2+.

Mobility driven thermoelectric and optical properties of two-dimensional halide-based hybrid perovskites: impact of organic cation rotation.

The pivotal impact of organic cation rotation may result in structural complexity in two-dimensional (2D) halide-based hybrid perovskites. The crucial role of the orientation of the organic cation (MA = CH3NH3+) in the 2D Ruddlesden-Popper phase (2DRP) is explored using density functional theory (DFT) calculations. Our results propose that the MA cation rotation imposes the structural distortion in the PbI6 network, which is further responsible for the changes in nature and value of the electronic bandgap, charge density and optical absorption. The spin-orbit coupling effect results in a wide range of Rashba splitting parameters being obtained from 0.04 to 0.278 eV Å. The simulated optical absorption spectra suggest that absorption edge for the alignment of the MA molecule along the X-axis (having unidirectional hydrogen bonds) is higher than that of the alignment of the MA cation in the z-direction. Furthermore, the unidirectional hydrogen bonds between the MA cation and Pb-I framework significantly help to achieve the highest mobility of charge carriers up to ∼1437 cm2 V-1 s-1. Such high mobility leads to supremacy in the thermoelectric transport properties, which are investigated for the first time with the rotation of the MA cation. The calculated thermoelectric power factor at room temperature shows exceptionally high values (up to 2.04 mW m-1 K-2), leading to desired applications in thermoelectric devices. The rotation of the MA cation might be utilized as a useful tool for variation in optical absorption and transport coefficients. Therefore, our results spark the idea to develop 2D perovskites for real-time perspective in solar and heat energy utilization.

Improvement in metal vapor laser performance with reduction in localized electric field at electrodes.

Electrode geometry plays a vital role in metal vapor laser performance. It has been observed that by modifying the electrode geometry, the electric field enhancement near the electrode can be reduced. Reduction in the localized electric field causes reduction in the phantom current in the metal vapor laser. On replacing the electrode geometry having eight pins with an electrode having the zero-pin configuration, a 10% decrease in the phantom current and a 23% increase in optical output power are observed. The low phantom current is responsible for higher efficiencies, large specific average output power, and improved beam characteristics of that laser in reference to a conventional copper vapor laser. It was also observed that reduction in field enhancement causes reduction in the thermal loading at the cathode fall and in the probability of thermal instability, thereby improving the discharge stability and jitter in metal vapor lasers. This simple and effective technique can also be applied to the systems requiring high current and high-volume stable discharge.

A comprehensive multidisciplinary investigation on CO2 capture from diesel engine.

Climate change and global warming are the visible consequences of the increased amount of carbon dioxide (CO2) in the atmosphere. Among the various sources of anthropogenic CO2 emission, the diesel engine has a significant contribution. The development of a reliable system to efficiently minimize CO2 emissions from diesel engines to the safest level is lacking in the open literature. Therefore, a comprehensive multidisciplinary approach has been applied in this paper to investigate the efficacy of the post-combustion carbon capture (PCC) process for the diesel engine. The experiments have been performed on the exhaust of a direct injection diesel engine at five different brake powers with blends of aqueous ammonia (AQ_NH3), monoethanolamine (MEA), N,N-dimethylethanolamine (DMEA), and 1-ethyl-3-methylimidazolium tetrafluoroborate (C2mim BF4) ionic liquid (IL) as an absorbent for CO2 capture. The reaction mechanism of these absorbent with CO2 are also studied by the geometrical, energetical, MESP, frontier molecular orbitals, and NBO analysis using the first-principles density functional theory (DFT) calculations. The maximum CO2 absorption efficiency of almost 97% was achieved for the blend consisting of 67% of AQ_NH3 and 33% of MEA. Moreover, AQ_MEA and blend of AQ_NH3, DMEA, and C2mim BF4 ionic liquid showed 96% and 94% CO2 absorption efficiency, respectively.

Evidences suggesting a possible role of Vitamin D in COVID 19: The missing link.

The severe acute respiratory syndrome coronavirus 2 is spreading like wildfire with no specific recommended treatment in sight. While some risk factors such as the presence of comorbidities, old age, and ethnicity have been recognized, not a lot is known about who the virus will strike first or impact more. In this hopeless scenario, exploration of time-tested facts about viral infections, in general, seems to be a sound basis to prop further research upon. The fact that immunity and its various determinants (e.g., micronutrients, sleep, and hygiene) have a crucial role to play in the defense against invading organisms, may be a good starting point for commencing research into these as yet undisclosed territories. Herein, the excellent immunomodulatory, antiviral, and anti-inflammatory roles of Vitamin D necessitate thorough investigation, particularly in COVID-19 perspective. This article reviews mechanisms and evidence suggesting the role Vitamin D plays in people infected by the newly identified COVID-19 virus. For this review, we searched the databases of Medline, PubMed, and Embase. We studied several meta-analyses and randomized controlled trials evaluating the role of Vitamin D in influenza and other contagious viral infections. We also reviewed the circumstantial and anecdotal evidence connecting Vitamin D with COVID-19 emerging recently. Consequently, it seems logical to conclude that the immune-enhancing, antiviral, anti-inflammatory, and lung-protective role of Vitamin D can be potentially lifesaving. Hence, Vitamin D deserves exhaustive exploration through rigorously designed and controlled scientific trials. Using Vitamin D as prophylaxis and/or chemotherapeutic treatment of COVID-19 infection is an approach worth considering. In this regard, mass assessment and subsequent supplementation can be tried, especially considering the mechanistic evidence in respiratory infections, low potential for toxicity, and widespread prevalence of the deficiency of Vitamin D affecting many people worldwide.

Sequential and cellular detection of copper and lactic acid by disaggregation and reaggregation of the fluorescent panchromatic fibres of an acylthiourea based sensor.

We report, for the first time, the self-assembly of an acyl-thiourea based sensor, N-{(6-methoxy-pyridine-2-yl) carbamothioyl}benzamide (NG1), with panchromatic fluorescent fibres and its dual-sensing properties for the sequential detection of Cu2+ ions and lactic acid. The panchromatic fibres formed by NG1 were disrupted in the presence of Cu2+ ions and this was accompanied by a visible colour change in the solution from colourless to yellow. The addition of lactic acid to the NG1 + Cu2+ solution, on the other hand, induced re-aggregation to fibrillar structures and the colour of the solution again changed to colourless. Hence, it may be surmised that the disaggregation and re-aggregation impart unique dual-sensing properties to NG1 for the sequential detection of Cu2+ ions and lactic acid. The application of NG1 as a selective sensor for Cu2+ ions and lactic acid has been assessed in detail by UV-visible and fluorescence spectroscopy. Furthermore, two structural variants of NG1, namely, NG2 and NG3, were synthesized, which suggest the crucial role of pyridine in imparting panchromatic emission properties and of both pyridine and acyl-thiourea side chain in the binding of Cu2+ ions. The O-methoxy group plays an important part in making NG1 the most sensitive probe of its structural analogs. Finally, the utility of NG1 for the sequential and cellular detection of Cu2+ ions and lactic acid was studied in human RPE cells. The experimental results of the interaction of NG1 with Cu2+ ions and lactic acid have also been validated theoretically by using quantum chemical calculations based on density functional theory (DFT). To the best of our knowledge, this is the first report wherein a dual sensor for Cu2+ ions and lactate ions is synthesized. More importantly, the aggregation properties of the sensor have been studied extensively and an interesting correlation of the photophysical properties of the probe with its self-assembling behavior has been elucidated.

Hybrid Structure of Ionic Liquid and TiO2 Nanoclusters for Efficient Hydrogen Evolution Reaction.

Hydrogen energy has received significant attention in the renewable energy sector due to its high energy density and environmentally friendly nature. For the efficient hydrogen generation from water, the hydrogen evolution reaction (HER) has to be optimized, which requires a highly efficient electrocatalyst. In this work, a hybrid structure of the ionic liquid (IL) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (C2mim TfO) and (TiO2)n nanoclusters with n = 2-12 has been investigated in the pursuit of new catalyst materials for effective HER. We have employed state-of-the-art density functional theory (DFT) computations to depict the HER catalytic performance of IL/(TiO2)n hybrid systems through Gibbs free energy (ΔG) and an exchange-current-based "volcano" plot. We have explored the effect of the TiO2 nanoclusters on the structural and electronic characteristics of the IL, calculating the adsorption energy, the energies of the highest occupied (HOMO) and lowest unoccupied molecular orbitals (LUMO), the HOMO-LUMO band gap Eg, and the work function ϕ. The variation in size of the TiO2 nanocluster in the IL/(TiO2)n hybrid system was found to have a significant influence on the electronic properties. The obtained results suggest that the ΔG of the hydrogen adsorption is remarkably close to the ideal value (0 eV) for the IL/(TiO2)5 system, which also reflects from the volcano plot, suggesting that this complex is the best HER catalyst among the studied systems; it might be even better than the traditional Pt-based catalyst. Thus, the present work suggests ways for the experimental realization of low-cost and multifunctional IL-based hybrid catalysts for clean and renewable hydrogen energy production.

Strong-field ionization of polyatomic molecules: ultrafast H atom migration and bond formation in the photodissociation of CH3OH.

Strong-field ionization induces various complex phenomena like bond breaking, intramolecular hydrogen migration, and bond association in polyatomic molecules. The H-atom migration and bond formation in CH3OH induced by intense femtosecond laser pulses are investigated using a Velocity Map Imaging (VMI) spectrometer. Various laser parameters like intensity (1.5 × 1013 W cm-2-12.5 × 1013 W cm-2), pulse duration (29 fs and 195 fs), wavelength (800 nm and 1300 nm), and polarization (linear and circular) can serve as a quantum control for hydrogen migration and the yield of Hn+ (n = 1-3) ions which have been observed in this study. Further, in order to understand the ejection mechanism of the hydrogen molecular ions H2+ and H3+ from singly-ionized CH3OH, quantum chemical calculations were employed. The dissociation processes of CH3OH+ occurring by four dissociative channels to form CHO+ + H3, H3+ + CHO, CH2+ + H2O, and H2O+ + CH2 are studied. Using the combined approach of experiments and theory, we have successfully explained the mechanism of intramolecular hydrogen migration and predicted the dissociative channels of singly-ionized CH3OH.

Fungal Endophytes as Efficient Sources of Plant-Derived Bioactive Compounds and Their Prospective Applications in Natural Product Drug Discovery: Insights, Avenues, and Challenges.

Fungal endophytes are well-established sources of biologically active natural compounds with many producing pharmacologically valuable specific plant-derived products. This review details typical plant-derived medicinal compounds of several classes, including alkaloids, coumarins, flavonoids, glycosides, lignans, phenylpropanoids, quinones, saponins, terpenoids, and xanthones that are produced by endophytic fungi. This review covers the studies carried out since the first report of taxol biosynthesis by endophytic Taxomyces andreanae in 1993 up to mid-2020. The article also highlights the prospects of endophyte-dependent biosynthesis of such plant-derived pharmacologically active compounds and the bottlenecks in the commercialization of this novel approach in the area of drug discovery. After recent updates in the field of 'omics' and 'one strain many compounds' (OSMAC) approach, fungal endophytes have emerged as strong unconventional source of such prized products.

Perceived Climate Variability and Compounding Stressors: Implications for Risks to Livelihoods of Smallholder Indian Farmers.

Micro-scale perspectives are seldom included in planned climate change adaptations, yet farmers' perceptions can provide useful insights into livelihood impacts from interactions between climatic and other stressors. This research aims to understand how climate variability and other stressors are impacting the livelihoods of smallholder farmers in Azamgarh district, eastern Uttar Pradesh, India. Data from 84 smallholder farmers were collected using mixed qualitative and quantitative approaches, including interview and participatory methods, informed by multiple stressor and sustainable livelihood frameworks. Results revealed that farmers are increasingly facing problems caused by the reduced duration and number of rainy days, and erratic rainfall. Anomalies in seasonal cycles (longer summers, shorter winters) seem to have altered the local climate. Farmers reported that repeated drought impacts, even in years of moderate rainfall, are adversely affecting the rice crop, challenging the formal definition of drought. Climate variability, identified as the foremost stressor, often acts as a risk multiplier for ecological (e.g., soil sodicity), socio-economic (e.g., rising costs of cultivation) and political (e.g., mismatching policies and poor extension systems) stressors. In addition to climate stresses, resource-poor marginal groups in particular experienced higher risks resulting from changes in resource management regimes. This study provides an important cue to revisit the formal definitions of normal rainfall and drought, accommodating farmers' perceptions that evenly distributed rainfall, and not total rainfall is a key determinant of crop yields. Though India has developed adaptive measures for climate change and variability, integration of farmers' perceptions of climate and other stressors into such policies can improve the resilience of smallholder farmers, who have hitherto depended largely on autonomous adaptation strategies.

Rashba Splitting in Two Dimensional Hybrid Perovskite Materials for High Efficient Solar and Heat Energy Harvesting.

The physical properties of two-dimensional (2D) lead halide based hybrid perovskites are quite exciting and challenging. Further, the role of organic cations in 2D perovskites is still in a debate. We investigated layered (CH3(CH2)3NH3)2(CH3NH3)Pb2I7 2D Ruddlesden-Popper (2DRP) phase (M1) and 2D derivative of CH3NH3PbI3 (M2) using density functional theory. The spin orbit coupling mediates the significantly large Rashba splitting energy of 328.5 meV for M2, which is higher than earlier 2D hybrid perovskites. At the picosecond time scale, the dynamical Rashba effect was observed due to organic and inorganic cation dynamics. Two step absorption suggests an indirect optical gap of 2.38 and 2.15 eV for M1 and M2, respectively and solar performance depicts excellent power conversion efficiency of 14.92% and 19.75% for M1 and M2, respectively. For the first time, we explored the thermoelectric properties of 2D hybrid perovskites and perceived high power factor for p-type doping in M2. Our findings suggest that these novel 2D perovskites have the potential to be used in solar and heat energy harvesting.