Systematic study of room-temperature ferromagnetism and the optical response of Zn1-x TM x S/Se (TM = Mn, Fe, Co, Ni) ferromagnets: first-principle approach

The structural, magnetic and optical characteristics of Zn_1-x TM _x S/Se (TM  =  Mn, Fe, Co, Ni and x  =  6.25%) have been investigated through the full-potential linearized augmented plane wave method within the framework of density functional theory. The optimized structures have been used to calculate the ferromagnetic and the antiferromagnetic ground-state energies. The stability of the ferromagnetic phase has been confirmed from the formation and the cohesive energies. The Heisenberg model is used to elucidate the Curie temperature (T _c) of these alloys. From the band structures and density of states plots, it has been observed that TM-doped ZnS/Se alloys appear to be semiconductors and exhibit ferromagnetism. In addition, the observed ferromagnetism has also been explained in terms of direct exchange energy Δ _x (d), exchange splitting energy Δ _x (pd), crystal-field energy (E _crys), exchange constants (N ₀ α and N ₀ β) and magnetic moments that shows potential spintronic applications. The optical behaviors of these alloys have been explained in terms of real and imaginary parts of the dielectric constant ε(ω), refractive index n(ω), extinction coefficient K(ω), reflectivity R(ω) and absorption coefficient σ(ω), in the energy range 0-25 eV. The calculated static limits of the band gaps and real part of the dielectric constants satisfy the Penn model. The critical limits of the imaginary part of the dielectric constants and absorption coefficients indicate that these alloys can be operated in the visible and the ultraviolet region of the electromagnetic spectrum; therefore, make them important for optoelectronic applications.

Establishing defined daily and course doses for antimicrobials used in Pakistani broilers to enable farm-level quantification and comparison of antimicrobial use

Monitoring antimicrobial use (AMU) is crucial, as it plays a key role in driving antimicrobial resistance (AMR). Animals account for a significant share of AMU, making it essential to accurately quantify AMU exposure at the species, farm, and country levels. In Pakistan, prophylactic use of antimicrobials remains common alongside therapeutic use. This study aimed to establish defined daily and course doses for both therapeutic and prophylactic use of antimicrobials in commercial broiler production in Pakistan. A list of antimicrobial products was compiled from the daily treatment records from 100 commercial broiler farms in Punjab, Pakistan. For each active substance (AS), a defined daily dose (DDDvetPK) was assigned for treatment, prevention or both, by averaging the recommended doses of all similar AS with the same administration route. A defined course dose (DCDvetPK) was calculated by multiplying the average recommended dose by the average treatment duration for each AS, based on the Summary of Product Characteristics (SmPC). A total of 41 AS, categorized into 17 antimicrobial classes, were identified from 139 antimicrobial products. The most frequently reported AS were colistin (polymyxins) at 15.9 %, amoxicillin (aminopenicillins) at 7.5 %, neomycin (aminoglycosides) at 7.3 %, enrofloxacin (fluoroquinolones) at 6.7 %, and tylosin (macrolides) at 6.4 % of the total treatments (n = 358) reported at farms. Notably, 51 % of AS were classified as critically important for human medicine by WHO. Among AS indicated for treatment in SmPC, the defined daily doses for Pakistan (DDDvetPK) varied substantially from the European Medicines Agency (EMA) values (DDDvet), with the top deviations being Tiamulin (+147.8 %), Sulfadimidine_TMP (+111.2 %), Flumequine (+88.6 %), Spiramycin (-87.8 %), and Tylosin (-84.3 %). This study presents a list of defined daily doses and defined course doses for AMU quantification in Pakistani broilers using dose-based indicators. The observed differences between Pakistani and EMA doses, and lack of EMA doses for preventive antimicrobials, suggest using Pakistani DDDvetPK values to quantify antimicrobial usage in Pakistan. A huge variation in recommended doses was reported in SmPC. There is an urgent need to establish a list of approved veterinary antimicrobials used in Pakistan, along with harmonization in recommended doses and maintenance of standardized SmPC by the drug regulatory authorities. Setting up a national-level list of defined daily doses is crucial to accurately monitor and quantify AMU.

First principles study of double perovskites Li2AgAsX6 (X = Cl, Br, I) for optoelectronic and thermoelectric applications

The present communication aims to provide a theoretical examination of the structural, electronic, optical, transport, and mechanical characteristics of Li2AgAsX6 (X = Cl, Br, I) to check their potential for optoelectronic and thermoelectric applications. The structural analysis reveals their cubic symmetry, and their structural and thermodynamic stability is verified through assessments of their tolerance factors (0.96, 0.94, and 0.93) and formation energies (-3.63, -3.10, and -2.16 eV). Their mechanical stability and ductile nature are confirmed using elastic constants, Poisson's ratio, and Pugh's criterion. Analysis of the band structure exhibits bandgaps of 0.86, 0.56, and 0.22 eV for Cl-, Br- and I-based compositions. Analysis of their optical behavior is carried out in terms of complex dielectric constant, complex refractive index, optical conductivity, reflectivity, and loss, providing better insight into material characteristics. The highest absorption in the infrared region underscores their prospects as infrared detectors. Additionally, the materials exhibit high electrical conductivity, and ultra-low lattice thermal conductivity with a considerable figure of merit, highlighting their feasibility for thermoelectric devices.

Computational screening of appealing perspectives of indium-based halide double perovskites In2AgSbX6 (X = Cl, Br, and I) for energy harvesting technologies

Halide double perovskites have attracted considerable attention for their potential use in solar cells and thermoelectric devices, as they are ecologically benign and possess band gap tunability. Herein, the stability, optoelectronic, and thermal transport characteristics of In2AgSbX6 (X = Cl, Br, and I) were examined using density functional theory (DFT). Ab initio molecular dynamics (AIMD) analysis was conducted, which verified the dynamic stability of In2AgSbX6 up to 700 K. The estimated elastic parameters further confirmed their mechanical stability. Through mechanical analysis, the asymmetric characteristics of In2AgSbX6 were revealed. The above-mentioned materials were ductile, validating their utilization in flexible or foldable technologies. Analyses of the electrical properties of In2AgSbCl6, In2AgSbBr6, and In2AgSbI6 showed indirect band gaps (E g) of 1.95 eV, 1.35 eV, and 0.78 eV, respectively. These electronic E g values were ideal for solar cell applications. The lower effective masses and binding energies of excitons of In2AgSbCl6, In2AgSbBr6, and In2AgSbI6 than those of the perspective solar cell candidates CsPbI3 and Cs2AgBiBr6 provided evidence for their effectiveness as absorber layer materials. The optical analysis of the dielectric constant, absorption, reflection, and loss demonstrated higher absorption, lower reflection, and minimal energy loss within the visible and ultraviolet spectra. The thermal transport features were analyzed for various temperatures up to 600 K and chemical potentials. In2AgSbCl6, In2AgSbBr6, and In2AgSbI6 demonstrated p-type nature, higher Seebeck coefficient, and ZT values of 0.75, 0.77, and 0.76, respectively. Thus, In2AgSbCl6, In2AgSbBr6, and In2AgSbI6 possessed feasible characteristics for applications in solar cells and thermal energy transformation, demonstrating that they can be utilized in future energy harvesting technologies.

Quantification of Antimicrobial Use on Commercial Broiler Farms in Pakistan

Pakistan has a large, intensive broiler production industry, where antimicrobials are extensively used for both therapeutic and prophylactic purposes. Monitoring antimicrobial use (AMU) at the farm level is crucial to guide interventions for antimicrobial stewardship. The objective of this study was to comprehensively quantify AMU on commercial broiler farms in Pakistan using different metrics. Data on on-farm AMU (both therapeutic and prophylactic) were collected from intensive commercial broiler farms in Punjab, Pakistan. AMU was quantified using four different metrics: treatment incidence (TI) based on defined daily dose (TIDDDvetPK), TI based on defined course dose (TIDCDvetPK), TI based on used daily dose (TIUDDvetPK), and mg/kg biomass. The median TIDDDvetPK, TIDCDvetPK, TIUDDvetPK, and mg/kg biomass values were 57.7 (7.5-257.9), 13.3 (1.8-52.5), 75.3 (21.1-182.9), and 301 (46.8-1009.6), respectively, based on 741 group treatments given at 100 participating farms with 225 flocks. About 34% treatments were administered for therapeutic purposes, with 66% administered as prophylaxis. A total of 41 active substances, distributed across 17 antimicrobial classes, were identified from 139 commercial antimicrobial products used. The most commonly used active substances (AS), out of total 741 group treatments, were colistin (polymyxins) at 17%, enrofloxacin (quinolones) at 8%, neomycin (aminoglycosides) and amoxicillin (aminopenicillins) at 7% each, and procaine penicillin (NS penicillins) and streptomycin (aminoglycosides) at 6% each. According to the WHO categorization, 57% of the used AS were found to be critically important antimicrobials (CIAs) for human medicine. As many as 30% of treatments were administered in the first week (13% on the first day of production), and the main indication was prophylaxis for early chick mortality, followed by 21% in week 5, with main indication being feed supplements for necrotic enteritis. The average weight at slaughtering was 2.25 kg, gained after an average of 44 days of the production cycle. The alarmingly high AMU in Pakistani broiler production emphasizes the urgent need to reduce AMU, particularly involving CIAs and the prophylactic use of antimicrobials. This can be achieved by improving farm management practices and strengthening regulatory oversight to enable prudent antimicrobial use, eventually reducing the risk of AMR.