Intrinsic Room-Temperature Ferromagnetism in New Halide Perovskite AgCrX3 (X: F, Cl, Br, I) Using Ab Initio and Monte Carlo Simulations

Herein, we present a detailed comparative study of the structural, elastic, electronic, and magnetic properties of a series of new halide perovskite AgCrX3 (X: F, Cl, Br, I) crystal structures using density functional theory, mean-field theory (MFT), and quantum Monte Carlo (MC) simulations. As demonstrated by the negative formation energy and Born-Huang stability criteria, the suggested perovskite compounds show potential stability in the cubic crystal structure. The materials are ductile because the Pugh's ratio is greater than 1.75, and the Cauchy pressure (C12-C44) is positive. The ground state magnetic moments of the compound were calculated as 3.70, 3.91, 3.92, and 3.91 μB for AgCrF3, AgCrCl3, AgCrBr3, and AgCrI3, respectively. The GGA + SOC computed spin-polarized electronic structures reveal ferromagnetism and confirm the metallic character in all of these compounds under consideration. These characteristics are robust under a ±3% strained lattice constant. Using relativistic pseudopotentials, the total energy is calculated, which yields that the single ion anisotropy is 0.004 meV and the z-axis is the hard-axis in the series of AgCrX3 (X: F, Cl, Br, and I) compounds. Further, to explore room-temperature intrinsic ferromagnetism, we considered ferromagnetic and antiferromagnetic interactions of the magnetic ions in the compounds by considering a supercell with 2 × 2 × 2 dimensions. The transition temperature is estimated by two models, namely, MFT and MC simulations. The calculated Curie temperatures using MC simulations are 518.35, 624.30, 517.94, and 497.28 K, with ±5% error for AgCrF3, AgCrCl3, AgCrBr3, and AgCrI3 compounds, respectively. Our results suggest that halide perovskite AgCrX3 compounds are promising materials for spintronic nanodevices at room temperature and provide new recommendations. For the first time, we report results for novel halide perovskite compounds based on Ag and Cr atoms.

Comparative pharmacokinetic evaluation of glimepiride orodispersable and conventional tablets in rabbits

OBJECTIVES

Glimepiride Orodispersable Tablets (ODT) were prepared with the goal to have rapid onset of action and higher bioavailability with ease administration to individuals with swallowing difficulty to ameliorate patient compliance.

SIGNIFICANCE

Glimepiride is a contemporary hypoglycemic medication that belongs to the family of sulfonylurea derivatives. It is used in type 2 diabetes mellitus. Compliance adherence remains one of the limitations with the conventional drug delivery system especially in pediatric, geriatric, psychiatric, and traveling patients, for such population ODT provides a good alternate dosage form compared with Commercial Tablets.

METHOD

The Comparative in vivo pharmacokinetic parameters of the prepared ODT and conventional tablets (CT) were evaluated using an animal model. The plasma concentration of Glimepiride after oral administration of a single dose was determined at predetermined time intervals with HPLC. The pharmacokinetic parameters were calculated using PK Solutions 2.0 from Summit PK® software.

RESULTS

The Cmax obtained with ODT (22.08 µg/ml) was significantly (p = 0.006) high, a lower tmax of 3.0 hr was achieved with the orodispersable formulation of the drug. The ODT showed 104.34% relative bioavailability as compared to CT and left shift of tmax as well.

CONCLUSION

As per findings of the in vivo investigation, the Glimepiride ODT would be beneficial in terms of patient compliance, quick onset of action, and increased bioavailability.

First-Principles Insights into Structural, Optoelectronic, and Elastic Properties of Fluoro-Perovskites KXF3 (X = Ru, Os)

The need for new and better semiconductor materials for use in renewable energy devices motivates us to study KRuF3 and KOsF3 fluoride materials. In the present work, we computationally studied these materials and elaborate their varied properties comprehensively with the assistance of density functional theory-based techniques. To find the structural stability of these under-consideration materials, we employed the Birch-Murnaghan fit, while their electronic characteristics were determined with the usage of modified potential of Becke-Johnson. During the study, it became evident from the band-structure results of the KRuF3 and KOsF3 materials that both present an indirect semiconductor nature having the band gap values of 2.1 and 1.7 eV, respectively. For both the studied materials, the three essential elastic constants were determined first, which were further used to evaluate all the mechanical parameters of the studied materials. From the calculated values of Pugh's ratio and Poisson's ratio for the KRuF3 and KOsF3 materials, both were verified to procure the nature of ductility. During the study, we concluded from the results of absorption coefficient and optical conduction in the UV energy range that both the studied materials proved their ability for utilization in the numerous future optoelectronic devices.

Hybrid Dissolving Microneedle-Mediated Delivery of Ibuprofen: Solubilization, Fabrication, and Characterization

Microneedles have recently emerged as a promising platform for delivering therapeutic agents by disrupting the skin, resulting in improved and high drug delivery via this route. Ibuprofen is widely used topically and orally for chronic pain conditions; to avoid untoward gastric effects, topical application is preferred over the oral route. This study aimed to enhance the solubility of the poorly water-soluble ibuprofen using Soluplus (SP) as a solubilizer and to fabricate dissolving microneedle patches of the drug. The fabricated patches were compared with marketed oral and topical formulations of ibuprofen. A 432-fold increase was observed in the solubility of the drug at 8% SP. The FTIR studies revealed that the drug and polymers were compatible. MNs were of uniform morphology and released the drug in a predictable manner. The in vivo analysis on healthy human volunteers revealed a Cmax of 28.7 µg/mL ± 0.5 with a T_max of 24 h and a MRT of 19.5 h, which was significantly higher than that observed for commercially available topical formulations. The prepared ibuprofen microneedles have higher bioavailability and MRT at a lower dose (165 µg) as compared to tablet and cream doses (200 mg).

Influence of Mn Ions’ Insertion in Pseudo-Tetragonal Phased CaBi4Ti4O15-Based Ceramics for Highly Efficient Energy Storage Devices and High-Temperature Piezoelectric Applications

In the present era of advanced technology, the surge for suitable multifunctional materials capable of operating above 300 °C has increased for the utilization of high-temperature piezoelectric devices. For this purpose, a pseudo-tetragonal phased CaBi₄Ti_3.98 (Nb_0.5Fe_0.5)_0.02O₁₅:xwt%MnO₂ (CBTNF:xMn), with x = 0–0.20, ceramic system has been engineered for the investigation of structural, ferroelectric, dielectric and high-temperature-dependent piezoelectric properties. XRD analysis confirms that low-content Mn-ion insertion at the lattice sites of CBTNF does not distort the pseudo-tetragonal phase lattice of CBTNF:xMn ceramics, but enhances the functional behavior of the ceramic system, specifically at x = 0.15 wt%Mn. Compared to pure CBT and CBTNF ceramics, CBTNF:0.15Mn has demonstrated a highly dense relative density (~96%), a saturated polarization (P_S) of 15.89 µC/cm², a storage energy density (W_ST) of ~1.82 J/cm³, an energy-conversion efficiency (ƞ) of ~51% and an upgraded piezoelectric behavior (d₃₃) of 27.1 pC/N at room temperature. Sharp temperature-dependent dielectric constant (ε_r) peaks display the solid ferroelectric behavior of the CBTNF:0.15Mn sample with a Curie temperature (T_C) of 766 °C. The thermally stable piezoelectric performance of the CBTNF:0.15Mn ceramic was observed at 600 °C, with just a 0.8% d₃₃ loss (25 pC/N). The achieved results signify that multi-valence Mn ions have effectively intercalated at the lattice sites of the pseudo-tetragonal phased CBTNF counterpart and enhanced the multifunctional properties of the ceramic system, proving it to be a durable contender for utilization in energy-storage applications and stable high-temperature piezoelectric applications.

The effect of substitutional doping of Yb2+on structural, electronic, and optical properties of CsCaX3(X: Cl, Br, I) phosphors: a first-principles study

Using first-principles calculations, the effects of Yb²⁺substitutional doping on structural, electronic, and optical properties of a series of perovskite compounds CsCaX₃(X: Cl, Br, I), have been investigated. We employed generalized gradient approximation (GGA) and HSE hybrid functional to study the electronic and optical properties. A series of pristine CsCaX₃(X: Cl, Br, I) is characterized as a non-magnetic insulator with indirect bandgap perovskite materials. These phosphor materials are suitable candidates for doping with lanthanide series elements to tune their electronic bandgaps according to our requirements because of their wide bandgaps. The calculated electronic bandgaps of CsCaX₃(X: Cl, Br, I) are 3.7 eV (GGA) and 4.5 eV (HSE) for CsCaI₃, 4.5 eV (GGA) and 5.3 eV (HSE) for CsCaBr₃, and 5.4 eV (GGA) and 6.4 eV (HSE) for CsCaCl₃. According to formation energies, the Yb²⁺doped at the Ca-site is thermodynamically more stable as compared to all possible atomic sites. The electronic band structures show that the Yb²⁺doping induces defective states within the bandgaps of pristine CsCaX₃(X: Cl, Br, I). As a result, the Yb²⁺doped CsCaX₃(X: Cl, Br, I) become the direct bandgap semiconductors. The defective states above the valence band maximum are produced due to thef-orbital of the Yb atom. The impurity states near the conduction band minimum are induced due to the major contribution ofd-orbital of the Yb atom and the minor contribution ofs-orbital of the Cs atom. The real and imaginary parts of the dielectric function, optical reflectivity, electron energy loss spectrum, extinction coefficient, and refractive index of pristine and Yb²⁺doped CsCaX₃(X: Cl, Br, I) were studied. The optical dispersion results of dielectric susceptibility closely match their relevant electronic structure and align with previously reported theoretical and experimental data. We conclude that the Yb²⁺doped CsCaX₃(X: Cl, Br, I) are appealing candidates for optoelectronic devices.

First-principles computational exploration of ferromagnetism in monolayer GaS via substitutional doping

Using first-principles calculations, functionalization of the monolayer-GaS crystal structure through N or Cr-doping at all possible lattice sites has been investigated. Our results show that pristine monolayer-GaS is an indirect-bandgap, non-magnetic semiconductor. The bandgap can be tuned and a magnetic moment (MM) can be induced by the introduction of N or Cr atomic anion/cation doping in monolayer GaS. For instance, the intrinsic character of monolayer GaS can be changed by substitution of N for the S-site to p-type, while substitution of Cr at the S-site or Ga-site induces half-metallicity at sufficiently high concentrations. The defect states are located in the electronic bandgap region of the GaS monolayer. These findings help to extend the application of monolayer-GaS structures in nano-electronics and spintronics. Since the S-sites at the surface are more easily accessible to doping in experiment, we chose the S-site for further investigations. Finally, we perform calculations with ferromagnetic (FM) and antiferromagnetic (AFM) alignment of the MMs at the dopants. For pairs of impurities of the same species at low concentrations we find Cr atoms to prefer the FM state, while N atoms prefer the AFM state, both for impurities on opposite surfaces of the GaS monolayer and for impurities sharing a common Ga neighbor sitting at the same surface. Extending our study to higher concentrations of Cr atoms, we find that clusters of four Cr atoms prefer AFM coupling, whereas the FM coupling is retained for Cr atoms at larger distance arranged on a honeycomb lattice. For the latter arrangement, we estimate the FM Curie temperatureT_Cto be 241 K. We conclude that the Cr-doped monolayer-GaS crystal structure offers enhanced electronic and magnetic properties and is an appealing candidate for spintronic devices operating close to room temperature.

Enhanced electronic and magnetic properties by functionalization of monolayer GaS via substitutional doping and adsorption

The structural, electronic, and magnetic properties of two-dimensional (2D) GaS are investigated using density functional theory (DFT). After confirming that the pristine 2D GaS is a non-magnetic, indirect band gap semiconductor, we consider N and F as substitutional dopants or adsorbed atoms. Except for N substituting for Ga (N_Ga), all considered cases are found to possess a magnetic moment. Fluorine, both in its atomic and molecular form, undergoes a highly exothermic reaction with GaS. Its site preference (F_S or F_Ga) as substitutional dopant depends on Ga-rich or S-rich conditions. Both for F_Ga and F adsorption at the Ga site, a strong F-Ga bond is formed, resulting in broken bonds within the GaS monolayer. As a result, F_Ga induces p-type conductivity in GaS, whereas F_S induces a dispersive, partly occupied impurity band about 0.5 e below the conduction band edge of GaS. Substitutional doping with N at both the S and the Ga site is exothermic when using N atoms, whereas only the more favourable site under the prevailing conditions can be accessed by the less reactive N₂ molecules. While N_Ga induces a deep level occupied by one electron at 0.5 eV above the valence band, non-magnetic N_S impurities in sufficiently high concentrations modify the band structure such that a direct transition between N-induced states becomes possible. This effect can be exploited to render monolayer GaS a direct-band gap semiconductor for optoelectronic applications. Moreover, functionalization by N or F adsorption on GaS leads to in-gap states with characteristic transition energies that can be used to tune light absorption and emission. These results suggest that GaS is a good candidate for design and construction of 2D optoelectronic and spintronics devices.

Effectiveness of muscle energy technique on cervical range of motion and pain

Every individual in his/her life experiences cervical pain at some stage which may restrict daily activities. Various approaches are available for the management of cervical pain, which include surgical, pharmacological and physical therapy. Different Manual therapy techniques are used for the treatment of neck pain. Muscle energy techniques and active isolated stretching are under consideration. This case series study was conducted at physical therapy department of North West General Hospital, Peshawar from August 2015 to January 2016 to find out the effectiveness of muscles energy techniques on cervical range of motion and pain. A total of 20 patients suffering neck pain, both genders having age of 25 - 50 years, cervical ROM limitation and muscles spasm were included in the study. Patients were treated by muscles energy technique (MET). The patient's outcome measures were Inclinometer and Visual Analogue Scale (VAS). Data was analyzed using SPSS version 20. The mean age was 32.3±6.53 years. The patient treated with muscles energy technique showed clinically improvement in the range of motion and pain. Results showed that pre and post treatment differences were statistically significant for cervical flexion (0.001), cervical extension (0.001), cervical right side rotation (0.001), cervical left side rotation (0.001), cervical right side bending (0.001), and cervical left side bending (0.01). Paired t-test finding for the pain showed statistically significant difference (0.005). It was concluded that Muscles Energy Technique is effective in the treatment of restricted range of motion and cervical pain.

Acute poisoning in southern part of Bangladesh--the case load is decreasing

This retrospective study was carried out in the Medicine Department of Khulna Medical College, the biggest tertiary hospital in the southern part of Bangladesh to observe the trends of poisoning in southern part of Bangladesh over four years including age and sex variation, mode of poisoning, type of poison used and outcome of poisoning. The hospital medical records of all patients, aged 10 years and above with history of acute poisoning from January, 2003 to December, 2006 were enrolled. Patients were categorized into four age group including Group (Gr.) I, Gr. II, Gr. III & Gr. IV having age range of 10-20, 21-30, 31-40 & >40 respectively. Underlying causes of poisoning were also observed totally and individually in different mode with male, female ratio and the percentage. Death cases according to mode of poisoning with demographic alignment were also observed. Statistical analysis were done using epi-info version 3.5.1 and measures were presented as proportion and percentage. Among 1903 cases, 1012 (53.1%) were male and 891 (46.8%) female with a ratio of 1.4: 1. The year wise total number of cases were progressively decreased from 627 (2003) to 353 (2006). Most commonly found toxic agent was Organo-Phosphate compound (526; 27.64%) with a very little sexual variation & this trend remained same in all study years. Poisoning with unknown substance was the second leading cause (16.03%) followed by Copper-sulphate (14.03%), Sedative (13.35%), Snakebite (12.93%) etc. Incidence of unknown poisoning, sedatives, snake-bite and corrosives were found to be gradually decreased over the study years. Male were found mostly affected in majority type of poisoning except Copper-sulphate, kerosene, puffer fish, paracetamol and other drugs category. Age group II (710; 37.3%) was the most vulnerable group with male (57.89%) preponderance followed by group I (643; 33.7%), III (329; 17.2%) and IV (221; 11.6%) respectively. Highest 1308 (68.7%) cases were suicidal in mode followed by 304 (15.9%) accidental and 291 (15.2%) homicidal. Out of 1903, 140 (7.3%) patients died. Death rate was highest in OPC poisoning (52.1%) followed by unknown substance (13.5%), snakebite and copper-sulphate (11.4%) etc. In an agro-based country like Bangladesh, it's very difficult to reduce the poisoning cases and mortality. Prospectively designed multi-centered studies are needed to reflect the epidemiological properties of poisonings throughout Bangladesh, and would be very valuable for the determination of preventive measures.

Anticonvulsant activities of the FS-1 subfraction isolated from roots of Delphinium denudatum

Delphinium denudatum Wall. (Ranunculaceae) is a medicinal herb used for the treatment of epilepsy in the subcontinent. The present study reports the anticonvulsant activities in the maximal electroshock test (MEST) and subcutaneous pentylenetetrazole (PTZ), bicuculline (BIC), picrotoxin (PIC)-induced seizures of the FS-1 subfraction (FS-1) that was obtained by purification of an aqueous fraction isolated from the roots of D. denudatum. In CF 1 mice, FS-1 (600 mg/kg i.p.) exhibited very potent anticonvulsant activity that was comparable to the effects of the well-known antiepileptic drug phenytoin (20 mg/kg) in MEST and protected 100% animals from hind limb tonic extension phase of this model. FS-1 also suppressed PTZ-induced threshold seizure and the loss of the righting reflex with tonic fore and hind limb extension by 100%, similar to the antiepileptic drug valproic acid (350 mg/kg). BIC-induced seizures were suppressed in 80% of the animals. FS-1 exhibited weak anticonvulsant effect on PIC-induced seizures, however, it significantly reduced mortality and delayed the onset of seizures. FS-1 had no effect on strychnine (STN)-induced extensor seizures. The results demonstrate the broad and potent anticonvulsant activity of the compounds in FS-1 of D. denudatum.

The inferior vena caval conduit--a neglected technique in transplantation of the right cadaveric kidney?

A short right renal vein may reduce access or compromise optimal positioning during transplantation of the right cadaveric kidney. This difficulty could be overcome by using the inferior vena cava (IVC) as a venous conduit to lengthen the short right renal vein. This manoeuvre would also facilitate training by ensuring safe tension-free vascular anastomoses since the kidney can be lifted up a comfortable distance, thus improving exposure of the operative field. In a postal survey, only a third of UK renal transplant units utilised the IVC conduit. Despite 81.5% of units claiming that they harvest the IVC during organ retrieval, a 2-year retrospective audit revealed that only 4.3% of imported right kidneys had the IVC. The IVC remains a much under-utilised resource in the UK despite its potential benefit as a venous conduit in transplanting the right cadaveric kidney. We urge all retrieving surgeons to routinely harvest the IVC with right cadaveric kidneys during organ procurement.

Two new quinones from Iris bungei

Two new benzoquinone derivatives, bungeiquinone (1) and dihydrobungeiquinone (2), and two known derivatives, 3-hydroxyirisquinone (3) and 3-hydroxydihydroirisquinone (4), were isolated from the roots of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods.

Preliminary antifungal and cytotoxicity studies of extracts of Ritchiea capparoides var. longipedicellata

Crude extracts obtained from the leaves, stem bark and roots of Ritchiea capparoides var. longipedicellata were screened for in vitro antifungal activity using the agar tube dilution method. The leaf hexane, leaf methanol, stem bark methanol and root methanol extracts were tested using ten clinical strains of fungi at a concentration of 200 and 400 microg/ml, respectively. At 400 microg/ml, all four extracts inhibited the growth of six of the ten test fungi used in the study. Inhibition of the growth of Aspergillus niger by the extracts was also seen but the activity was low and the leaf hexane and root methanol extracts inhibited the growth of Drechslera rostrata. Only the leaf hexane extract was active against Curvularia lunata, while the growth of Candida albicans was not inhibited by any of the extracts. The inhibition of growth of almost all the microorganisms decreased at 200 microg, griseofulvin was included as a reference compound and methanol as the control. Preliminary cytotoxicity tests were done with the four extracts using the larvae of the brine shrimp, Artemia saline. The extracts were however found to be relatively non-toxic as each extract had an LD50 value greater than 1000 microg/ml.