Designing new ferromagnetic double perovskites: the coexistence of polar distortion and half-metallicity

Advancing technology and growing interdisciplinary fields raise the need for new materials that simultaneously possess several significant physics quantities to meet human demands. In this research, using density functional theory, we aim to design A₂MnVO₆ (A = Ca, Ba) as new double perovskites and investigate their structural, electronic, and magnetic properties. Structural calculations based on the total energies show the optimized monoclinic and orthorhombic crystal structures for the Ca₂MnVO₆ (CMVO) and Ba₂MVO₆ (BMVO) compounds, respectively. Through performing calculations, we reveal that the Jahn-Teller effect plays an important role in polar distortions of VO₆ and elongation of MnO₆ octahedra, resulting from the V⁵⁺(3d⁰) and Mn³⁺(3d⁴:t32ge1g) electron configurations. The spin-polarized calculations predict the half-metallic ferromagnetic ground state for CMVO and BMVO with a total magnetic moment of 4.00 μ_B f.u.^-1 Our findings introduce CMVO and BMVO double perovskites as promising candidates for designing ferromagnetic polar half-metals and spintronic applications.

Development and validation of a rapid HPLC method for simultaneous analysis of budesonide and its novel synthesized hemiesters in colon specific formulations

A simple and reliable reversed-phase high performance liquid chromatographic (HPLC) method was developed, validated and applied for determination of budesonide and its novel synthesized hemiesters in colon specific formulations and dissolution media. The method was employed on a μ-Bondapak C(18) column (250 mm × 4.6 mm, 5 μm) at ambient temperature. The mobile phase consisted of acetonitrile: monobasic potassium phosphate containing orthophosphoric acid (55:45, pH 3.2) at a flow rate of 1 ml/min. The UV detection wavelength was set at 244 nm and 50 μL of sample was injected into the HPLC system. Dexamethasone was used as the internal standard. The retention times for internal standard and budesonide were 4.5 and 7.2 min, respectively. The method was linear in the concentration range of 1-20 μg/ml of budesonide (R(2)>0.999). Limit of detection and limit of quantitation were 0.05 and 0.5 μg/ml, respectively. The method presented the requisite accuracy, selectivity, sensitivity and precision and showed good resolution for separation of the drug and related derivatives in the presence of excipients. The proposed method was successfully used for analysis of the drug and its derivatives in dissolution media and oral colon specific formulations prepared in our laboratory with enough reproducibility.

Development of novel budesonide pellets based on CODES(TM) technology: In vitro/in vivo evaluation in induced colitis in rats

BACKGROUND AND THE PURPOSE OF THE STUDY

Budesonide is the drug of choice for treatment of active inflammatory bowel disease (IBD). The aim of this study was to develop budesonide pellets based on a novel colon drug delivery system (CODES).

METHODS

Pellet cores containing lactulose or mannitol were prepared by extrusion/spheronization and coated with an acid soluble polymer (Eudragit E100), hydroxypropylmethyl cellulose (HPMC) and an enteric coat (Eudragit FS 30D) sequentially. In vitro drug release of coated pellets was studied using USP dissolution apparatus type II in buffers of pH 1.2 (2 hrs), pH of 7.4 (4 hrs) and pH of 6.8 containing 8% rat cecal contents (RCC) (18 hrs). The efficacy of the optimized formulation (containing 50% lactulose coated with Eudragit E (30% w/w) and Eudragit FS 30D (12% w/w)) was evaluated against 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats.

RESULTS

The results of the kind of bacteria in vitro dissolution tests indicated absence of drug release in pHs of 1.2 and 7.4 and controlled release in buffer of pH 6.8 containing RCC. It was found that release rate was controlled by the type and amount of polysaccharide and the thickness of the acid soluble layer. The prepared formulation showed promising results in alleviating the conditions of experimental model of colitis.

CONCLUSION

The results of this study suggest that pellets based on CODES technology could be useful for colonic delivery of budesonide.

Density functional study of structural, electronic and magnetic properties of new half-metallic ferromagnetic double perovskite Sr2MnVO6

In this paper, a new half-metallic (HM) double perovskite compound is predicted with the simultaneous presence of ferromagnetism and polar distortion. The structural, electronic and magnetic properties of Sr₂MnVO₆ (SMVO) are calculated by density functional theory (DFT) with both generalized gradient approximation (GGA) and GGA  +  U approaches, where U is the on-site Coulomb interaction parameter. Different orderings of B (B') cationic sites in A₂BB'O₆ double perovskite structure are evaluated, including rocksalt, columnar and layered arrangements for cubic, monoclinic and tetragonal crystal structures. It is found that the most stable ordering is obtained when B and B' are placed in a layered type ordering for a tetragonal crystal structure with I4/m space group, which is confirmed by phonon calculations. The B-site ordering of the Mn³⁺ and V⁵⁺ ions in a layered configuration leads to ferromagnetically coupled magnetic moments of 4.17 µ _B at Mn site and 0.23 µ _B at V site. Finally, SMVO is found to be a half-metallic ferromagnetic (HM-FM) compound with a band gap of 0.65 eV in a spin down channel with off-centered displacement of V atoms in the octahedral cage (second order Jahn -Teller effect) which can cause ferroelectricity. Therefore, SMVO is predicted to be a polar HM material and a promising candidate for multiferroic property with potential application in spintronics.

Intraoperative central nipple biopsy in nipple-sparing mastectomy- A retrospective analysis of 211 patients

Subcutaneous nipple sparing mastectomies (NSM) are an important tool in modern oncoplastic surgery. Especially when an immediate implant-based reconstruction (IBR) is desired, clean margins are of the utmost importance. Central nipple biopsies during surgery serve two main purposes. Most importantly, it is hypothesized that intraoperative pathological evaluation of this biopsy may increase clean margin resection rates. In addition, a general recurrence risk reduction may occur due to the elimination of glandular and ductal components within the nipple. This analysis is a single center, multi-surgeon, retrospective, head to head analysis. Starting in March 2015, intraoperative central nipple biopsy in NSMs with IBR was introduced at the Municipal Breast Cancer Centre Cologne, Holweide, Germany. This trial retrospectively evaluates global complication rates, clean margin status and local recurrence rates for cohort 1 (NSM/no nipple biopsy, n = 103) vs. cohort 2 (NSM with nipple biopsy, n = 108) Median follow-up was 15 months. All implant-based reconstruction procedures used an epipectoral implant pocket. Cohorts were comparable. Global complication rates slightly favored the nipple biopsy cohort with respects to implant loss rate. An involved central nipple biopsy was found in 4.6% (n = 5/108) of the performed NSM procedures leading to the immediate removal of the nipple areola complex. All positive retro-areolar biopsies correlated with a positive nipple biopsy. However, in n = 1 case we found DCIS discontinual proliferation with an involved nipple biopsy, without a correlating positive retro-areolar biopsy (ie, 1 false-negative case was prevented). For the 15 month follow-up, there was no case of local recurrence within nipple areola complex for both cohorts. With this retrospective head to head analysis of 211 patients, it was shown that the central nipple biopsy correlates well with the retro-areolar biopsy. There may be a reduction in false negative rates. The procedure is safe to use and should be offered to NSM patients.

A theoretical study of new polar and magnetic double perovskites for photovoltaic applications

Searching for novel functional materials has attracted significant interest for the breakthrough in photovoltaics to tackle the prevalent energy crisis. Through density functional theory calculations, we evaluate the structural, electronic, magnetic, and optical properties of new double perovskites Sn2MnTaO6 and Sn2FeTaO6 for potential photovoltaic applications. Our structural optimizations reveal a non-centrosymmetric distorted triclinic structure for the compounds. Using total energy calculations, antiferromagnetic and ferromagnetic orderings are predicted as the magnetic ground states for Sn2MnTaO6 and Sn2FeTaO6, respectively. The empty d orbitals of Ta5+-3d0 and partially filled d orbitals of Mn/Fe are the origins of ferroelectricity and magnetism in these double perovskites resulting in the potential multiferroicity. The studied double perovskites have semiconducting nature and possess narrow band gaps of approximately 1 eV. The absorption coefficient (α) calculations showed that the value of α in the visible region is in the order of 105 cm-1. The structural stability, suitable band gap, and high absorption coefficient values of proposed compounds suggest they could be good candidates for photovoltaic applications.

Photonic Materials Cloud: An Online Interactive Open Tool for Creating, Comparing, and Testing Photonic Materials

Recent advances in nanoscale fabrication and characterization further accelerated research on photonics and plasmonics, which has already attracted long-standing interest. Alongside morphological constraints, phenomena in both fields highly depend on the materials’ optical properties, dimensions, and surroundings. Building up the required knowledge and experience to design next-generation photonic devices can be a complex task for novice and experienced researchers who intend to evaluate the impact of subtle material and morphology variations while setting up experiments or getting a general overview. Here, we introduce the Photonic Materials Cloud (PMCloud), a web-based, interactive open tool for designing and analyzing photonic materials. PMCloud allows identification of the subtle differences between optical material models generated from a database, experimental data input, and inline-generated materials from various analytical models. Furthermore, it provides a fully interactive interface to evaluate their performance in important fundamental (numerical) optical experiments. We demonstrate PMCloud’s applicability to state-of-the-art research questions, namely the comparison of the novel plasmonic materials aluminium-doped zinc oxide and zirconium nitride and the design of an optical, dielectric thin-film Bragg reflector. PMCloud opens a rapid, freely accessible path towards prototyping optical materials and simple fundamental devices and may serve as an educational platform for photonic materials research.

Effects of Aloe vera cream on chronic anal fissure pain, wound healing and hemorrhaging upon defection: a prospective double blind clinical trial

Aloe vera is a medicinal plant that promotes wound healing in burn injuries. A prospective clinical trial was conducted to evaluate the effects of a topical cream containing 0.5% Aloe vera juice powder in the treatment of chronic anal fissures. The aloe cream was applied by the patients to the wound site 3 times per day for 6 weeks following the instructions of a physician. Pain was assessed with a visual analog scale before treatment and at the end of each week of treatment. Wound healing and the amount and severity of bleeding were examined and evaluated before and at the end of each week of treatment. There were statistically significant differences in chronic anal fissure pain, hemorrhaging upon defection and wound healing before and at the end of the first week of treatment also in comparison with control group (p < 0.0001). In this study, a topical cream containing aloe vera juice was an effective treatment for chronic anal fissures. This is a promising result indicating that further comparative studies are justified.