Preparation and Properties of CuCr1 – x V x Se2 Solid Solutions

The phase relations in the CuSe–(1 – x)CrSe–xVSe system were studied. The system was found to contain CuCr_{1 – x} V _x Se₂ solid solutions isostructural with CuCrSe₂. The solid-solution range and oxidation states of Cr and V were determined.     

Preparation and Magnetic Properties of CuCr1 – x Mn x S2 Solid Solutions

Phase relations in the CuS–CrS–MnS system (20 mol % MnS) were studied. The system was found to contain CuCr_{1 – x} Mn _x S₂ solid solutions isostructural with CuCrS₂. The solid-solution range and the oxidation states of Cr and Mn were determined.     

Miconazole and Miconazolenitrate Chewing Gun as Drug Delivery Systems – A Practical Application of Solid Dispersion Technique

Abstract

Miconazole and miconazolenitrate are antifungal drugs with poor solubilities in water and saliva. The low solubilities meant that only small amounts of the drugs – incorporated by a conventional method in chewing gum-were released during mastication. The experiments were performed on a mastication device.

In this study it was shown that application of a 20% miconazole – 80% polyethyleneglycol 6000 solid dispersion drastically improved the in vitro release of miconazole from cheving gum, when a medium similar to saliva was used. In addition to polyethyleneglycol 6000, polyvinylpyrrolidone 40000, xylitol and urea were tested as carriers. It was also shown that the release rate of miconazole from chewing gum was much greater than the release rate of miconazolenitrate.

No certain correlation could be shown between the dissolution rates of the solid dispersions measured by a stirring paddle method and the release rates of miconazole from solid dispersions in chewing gum.

The solid dispersion systems were characterized by differential scanning calorimetry. The systems containing polyethyleneglycol 6000 and xylitol were eutectic. Polyvinylpyrrolidone 40000 prevented crystallisation of miconazole when the percentage of drug in the solid dispersion was less than 50%.     

Stability and In Vitro Drug Release of Flurbiprofen-Loaded Poly-ε-Caprolactone Nanospheres

The effects of temperature and two different initial pH (2.67 and 7.00) on poly-ε-caprolactone (PεCL) nanospheres loaded with flurbiprofen (FB) (aqueous suspensions) were studied to investigate their influence on the stability and physicochemical characteristics of these drug delivery systems. The drug release behavior was also studied. Release of the associated FB occurred very fast on high dilution in a buffered medium. The stability of the polymeric system depends on the temperature and the initial pH value; it is more degradable with the particles stored at 40°C with an initial pH value of 2.67.     

Preparation and Properties of Pb1 – xSnxTe1 – ySeyEpilayers

Pb_{1 – x} Sn _x Te_{1 – y} Se _y layers lattice-matched with KCl and BaF₂are grown by liquid-phase epitaxy. Epilayer compositions and growth temperatures are determined at which p- and n-type materials can be obtained without doping. The composition dependences of the Hall coefficient and carrier mobility are analyzed.     

Supercritical Antisolvent Versus Coevaporation— Preparation and Characterization of Solid Dispersions

The objective of this work was to improve the dissolution rate and aqueous solubility of oxeglitazar. Solid dispersions of oxeglitazar in PVP K17 (polyvinilpyrrolidone) and poloxamer 407 (polyoxyethylene-polyoxypropylene block copolymer) were prepared by supercritical antisolvent (SAS) and coevaporation (CoE) methods. Drug-carrier formulations were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, gas chromatography, UV/VIS spectroscopy and in vitro dissolution tests. The highest dissolution rate (nearly 3-fold higher than raw drug) was achieved by preparation of drug/PVP K17 coevaporate. Oxeglitazar/PVP K17 solid dispersions were stabilized by hydrogen bonding but contained higher amount of residual dichloromethane (DCM) than poloxamer 407 formulations regardless of the method of preparation. SAS prepared oxeglitazar/poloxamer 407 dissolved more than two times faster than raw drug. However, unlike PVP K17, poloxamer 407 did not form a single phase amorphous solid solution with oxeglitazar which has been manifested in higher degrees of crystallinity, too. Among the two techniques, evaluated in this work, conventional coevaporation resulted in higher amorphous content but SAS reduced residual solvent content more efficiently.     

Preparation and Evaluation of pH‐Dependent Gradient‐Release Pellets for TCM

This paper is designed to investigate a novel sustained release system for Traditional Chinese Medicinal Compound Recipe (TCMCR) by incorporating three kinds of pH‐dependent gradient‐release coated pellets into capsules. In our study, dosage reform was conducted on the TCMCR model drug–Guanxin Suhe Wan (GSW), which is in the traditional form of honey bolus, comprising Styrax, Borneolumsyntheticum, Olbanum, Radix aristolochiae and Lignum santali albi. In this study, the β‐CD inclusion complexes were prepared separately for Styrax, Borneolumsyntheticum and the volatile oil extracted from the mixture of Olbanum, Radix aristolochiae and Lignum santali albi. Pellets were prepared in a centrifugal granulator using the powder layering technique and then divided into 3 equal weight portions and coated with HPMC, HPMCP HP‐55 and Eudragit L100/S100 to obtain gradient release in stomach, duodenum and jejunum or ileum respectively. On this basis, a pH‐dependent sustained‐release pellets system, “Guanxin Suhe Sustained‐release Capsules”(GSSC), was prepared by mixing the above three kinds of coated pellets at the weight ratio of 1:1:1. Pharmacokinetic (PK) studies between GSW and GSSC were made on male volunteers and isolated guinea pig hearts by plasma drug concentration method and serum pharmacology method respectively. In plasma drug concentration method, T_max was 0.42 h and 1.08 h for GSW and GSSC respectively, while in the serum pharmacology method, T_max was 0.56 h and 0.52 h respectively. The relative bioavailability of GSSC to GSW was 95.62% and 121.82% separately in the above two methods, indicating a similarity between the two methods in predicting the PK behavior of GSSC.     

Preparation and Evaluation of Eudragit® Acrylic Resin for Controlled Drug Release of Pseudoephedrine Hydrochloride

Abstract

The preparation of a sustained release dosage form for pseudoephedrine hydrochloride was evaluated. Beadlets (PS) containing pseudoephedrine hydrochloride were prepared by spraying a slurry of pseudoephedrine hydrochloride, Eudragit® S-100, dibutyl sebacate and alcohol onto non-pariel seeds via the Wurster column process. The oven-dried PS beadlets were coated with different levels of Eudragit® RS (poorly water permeable) and Eudragit® S-100 (enteric resin). In-vitro dissolution     

In situ and operando characterisation of Li metal – Solid electrolyte interfaces

The use of lithium metal as the negative electrode holds great promise for high energy density solid-state batteries (SSBs) of the future, but at the same time presents major technical challenges in their development. Li metal, with its high reactivity, soft and ductile nature, and propensity towards mechanical deformation during electrochemical cycling, is susceptible to the formation of various defects such as voids, cracks and filamentary deposits at the Li metal - solid electrolyte interface, that eventually cause rapid degradation of electrochemical cell performance. In order to gain insights into these interfacial processes and identify mechanisms for failure, in situ and operando characterisation approaches are essential. In this perspective, we present our opinions on the current state of such techniques, while highlighting the existing limitations and scope of these methods. We also endeavour to present opportunities for future research into developing and building on existing approaches to better evaluate the Li metal-solid electrolyte interface so as to guide the appropriate choice of materials to further enable efficient SSB architectures.     

Sol-gel Preparation and Preliminary in vitro Evaluation of Fluorapatite／Hydroxyapatite Solid Solution Films

Fluorapatite/hydroxyapatite solid solution has better biological properties than other apatites, especially used as films or coatings. In this work, sol-gel preparation and in vitro behavior of fluorapatite/hydroxyapatite solid solution films on titanium alloy were investigated. Ca(NO3)2-4H20 and PO(OH)x(OEt)3-x were selected as precursors, and hexafluorophosphoric acid (HPFo) was used as a fluorine containing reagent. The Ca and P precursors were mixed with HPFo to keep the Ca/P molar ratio 1.67. The mixtures refluxed for 12 h were used as dipping sols for the preparation of the films. The phase of the films obtained at 600℃ was apatite. The F contents in the films increased with the concentrations of HPF6 in the dipping sols. The solid solution films were shown to have better stability than hydroxyapatite films, and a reasonably good bioactivity in the in vitro evaluation.     

Effect of PVP K30 and/or l-Arginine on Stability Constant of Etoricoxib–HPβCD Inclusion Complex: Preparation and Characterization of Etoricoxib–HPβCD Binary System

The effect of polyvinyl pyrrolidone (PVP) K30 and/or l-arginine on etoricoxib–HPβCD complex was investigated. The phase solubility profiles were classified as A_L-type, both in absence or presence of auxiliary substances used. The apparent stability constant (K_c) of binary complex obtained at room temperature, 371.80 ± 2.61 M^?1, was decreased with the addition of PVP and arginine indicating no benefit of addition of auxiliary substances to promote higher complexation efficiency. Therefore, solid etoricoxib–HPβCD binary systems were prepared and characterized by proton nuclear magnetic resonance spectroscopy (¹HNMR), X-ray powder diffractometry, Fourier transformation-infrared spectroscopy, and dissolution studies. Among all binary systems, a lyophilized product showed superior performance in enhancing dissolution of etoricoxib.     

Structural and Thermal Properties of Cu1 – xAgxInS2Chalcopyrite Solid Solutions

The anisotropic thermal expansion of Cu_{1 – x} Ag _x InS₂chalcopyrite solid solutions was studied by x-ray diffraction from 80 to 650 K. Over the entire temperature range studied, the thermal expansion of the solid solutions was found to be anisotropic: thec-axis thermal expansion is considerably smaller than thea-axis thermal expansion. The solid solutions with 0.55 <x< 1.0 exhibit negative c-axis thermal expansion. The composition dependences of the thermal expansion coefficients and anisotropy parameters are nonlinear. The anisotropy parameters rise monotonically with increasing x. The correlation between the thermal expansion anisotropy and tetragonal distortion = 2 – c/ais considered. Directions of zero thermal expansion are identified.     

The Use of Precirol® to Prepare Sustained Release Tablets of Theophylline and Quinidine Gluconate

Abstract

Tablets were made using theophylline, lactose and Precirol by a granulation technique, resulting in more than 12 hours release. Granulation and hot fusion methods were used to prepare admixtures of quinidine gluconate and Precirol at different ratios of Precirol: drug, 1:9, 3:7 and 1:1. Dissolution studies in 0.1N HCl showed drastic differences in the release of quinidine gluconate from tablets made by the two different methods; granulation method gave a faster release while the hot fusion method gave slower and incomplete release at higher Precirol content. The release rate decreases with higher Precirol content.     

Effect of Humidity on The Formation and Stability of Acetaminophen-β-Cyclodextrin Inclusion Complexes

Abstract

The effect of humidities (75% RH and 100% RH) on the inclusion complex formation and crystallizing behavior of physical mixture and ground mixture of acetaminophen with α-cyclodextrin, β-cyclodextrin or microcrystalline cellulose at 30 °C were studied by DSC thermal analysis, X-ray diffractometer, IR spectrophotometer. The change of water content in the physical mixture and ground mixture when stored at 30 °C, 75% RH or 100% RH was determined. The results indicate that the inclusion complex formation and crystallizing behavior of these mixtures were dependent on the relative humidity and types of cyclodextrins. The physical mixture of acetaminophen and β-cyclodextrin stored at 30 °C and 100% RH was transformed to crystalline inclusion complex, but stored at 75% RH still exhibited a behavior of physical mixture. The ground mixture of acetaminophen and β-cyclodextrin was converted amorphous inclusion complex to crystalline inclusion complex whether stored at 75% RH or 100% RH. However, physical mixture and ground mixture of acetaminophen and α-cyclodextrin or microcrysatlline cellulose when stored at 75% RH or 100% RH belonged to a crystalline physical mixture.     

Preparation of Ultrafine Tetragonal ZrO2–CeO2Solid Solutions

Nanometer-sized tetragonal Zr_{1 – x} Ce _x O_{2 –} powders were prepared by hydroxide precipitation and sol–gel processing. The effects of gel-aging time and solution concentration on the phase composition and particle size of the powders were studied. The ceramics prepared by sintering ultrafine powders at 1500°C had a density of 6.0 g/cm³, open porosity of 4%, and closed porosity below 1%.     

Preparation and Characterization of Solid Dispersions of Dipyridamole with a Carrier “Copolyvidonum Plasdone®S-630”

Solid dispersions (SDs) of dipyridamole (DIP) with a novel carrier copolyvidonum Plasdone®S-630 (CoPVP) were developed by solvent evaporation method. The solid state of SDs of DIP with CoPVP (SDs CoPVP) was characterized by fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and polarizing microscopy, compared with that of SDs of DIP with polyvinylpyrrolidone Plasdone®K-29/32 (SDs PVP). FT-IR analysis demonstrated the presence of intermolecular hydrogen bonding between DIP and CoPVP or PVP in SDs. DSC and XRD studies indicated that DIP presented in amorphous state in both SDs CoPVP and SDs PVP at higher weight ratios. The dissolution property of SDs CoPVP was significantly improved in comparison of pure DIP and physical mixtures with CoPVP (PM CoPVP). Both SDs CoPVP and SDs PVP powder showed the favorable flowability. However, SDs CoPVP showed better compressibility than SDs PVP. The lower hydroscopicity of SDs CoPVP could be advantageous to the stability to SDs. This study proves the potential of CoPVP as a carrier in the formulations of SDs for poorly soluble drugs.     

Preparation of water dispersible,fluorescent Ag–PAA–PVP hybrid nanogels and their optical properties

A simple method of synthesizing hybrid silver–polyacrylic acid–poly(N-vinylpyrrolidone) (Ag–PAA–PVP) nanogels was demonstrated through in situ reducing Ag⁺ inside PAA–PVP nanogels, which were formed by polymerization of acrylic acid in the PVP solution. Due to the ion exchange between Ag⁺ and acid protons of PAA, stable Ag⁺ clusters were formed inside the PAA–PVP nanogels, and hybrid nanogels were obtained by reducing Ag⁺ by ascorbic acid. Transmission electronic microscopic (TEM) images clearly showed the existence of silver nanoparticles inside the Ag–PAA–PVP nanogels. These hybrid nanogels showed typical surface plasma resonance absorption peak around 420 nm, and the size of the silver nanoparticles inside the Ag–PAA–PVP nanogels could be controlled from 9.5 ± 1.6 nm to 1.9 ± 0.4 nm by increasing the feeding amount of Ag⁺. In addition, these hybrid nanogels showed photoluminescent properties in fluorescent spectra. Considering the pH sensitive property of these hybrid nanogels, they will have potential application in drug delivery and biomedical imaging systems.     

Formulation and Characterization of a Compacted Multiparticulate System for Modified Release of Water-Soluble Drugs – Part 1 Acetaminophen

The aim of this study was to characterize and evaluate a modified release, multiparticulate tablet formulation consisting of placebo beads and drug-loaded beads. Acetaminophen (APAP) bead formulations containing ethylcellulose (EC) from 40–60% and placebo beads containing 30% calcium silicate and prepared using 0–20% alcohol were developed using extrusion–spheronization and studied using a central composite experimental design. Particle size and true density of beads were measured. Segregation testing was performed using the novel ASTM D6940-04 method on a 50:50 blend of uncoated APAP beads (60%EC) : calcium silicate placebo beads (10% alcohol). Tablets were prepared using an instrumented Stokes-B2 rotary tablet press and evaluated for crushing strength and dissolution rate. Compared with drug beads (60%EC), placebo beads (10% alcohol) were smaller but had higher true densities: 864.8 μm and 1.27 g/cm³, and 787.1 μm and 1.73 g/cm³, respectively. Segregation testing revealed that there was approximately a 20% difference in drug content (as measured by the coefficient of variation) between initial and final blend samples. Although calcium silicate-based placebo beads were shown to be ineffective cushioning agents in blends with Surelease^®-coated APAP beads, they were found to be very compactibile when used alone and gave tablet crushing strength values between 14 and 17 kP. The EC in the APAP bead matrix minimally suppressed the drug release from uncoated beads (t_100%?=?2 h). However, while tablets containing placebo beads reformulated with glycerol monostearate (GMS) showed a slower release rate (t_60%= 5 h) compared with calcium silicate-based placebos, some coating damage (～30%) still occurred on compression as release was faster than coated APAP beads alone. While tablets containing coated drug beads can be produced with practical crushing strengths (>8 kP) and low compression pressures (10–35 MPa), dissolution studies revealed that calcium silicate-based placebos are ineffective as cushioning agents. Blend segregation was likely observed due to the particle size and the density differences between APAP beads and calcium silicate-based placebo beads; placebo bead percolation can perhaps be minimized by increasing their size during the extrusion–spheronization process. The GMS- based placebos offer greater promise as cushioning agents for compacted, coated drug beads; however, this requires an optimized compression pressure range and drug bead : placebo bead ratio (i.e., 50:50).     

Preparation and Properties of Silicate Glasses Containing CdSe x Te1 – x Nanoparticles

Data are presented on the formation of ultrafine CdSe _x Te_{1 – x} (0 x 1) particles in silicate glass. By introducing CdSe, CdTe, or CdSe _x Te_{1 – x} particles into glass batches, glasses are obtained which contain semiconductor nanoparticles formed during melt cooling. The absorption spectrum of the glasses thus prepared depends on the composition, concentration, and structure of the semiconductor nanoparticles.     

Fast and Huge Anisotropic Diffusion of Cu(Ag) and Its Resistance on the Sn Self-diffusivity in Solid β–Sn

The site preferences,fast and huge anisotropic diffusion mechanisms of Cu(Ag) in β-Sn as well as their reduction on the self-diffusivity of Sn,have been investigated using the first-principles and ab initio molecular dynamics methods.We have found that Cu prefers the interstitial site,whereas Ag is preferable in the substitutional site,which is mostly dominated by their different size factors.Electronic structure further evidences that the d-s hybridization between the solute and the host atom also contributes to the site preferences.It is also deduced that the fast diffusion of Cu(Ag) is mostly due to the interstitial diffusion mechanism and their diffusivity can be correlated with the amount of their respective interstitial solution.Their faster diffusion along the c-axis can be attributed to the extremely low migration energy barrier caused by the straight tunnel of considerable size with the screw axis symmetry of 2π/4along the c-axis.Furthermore,it is found that during the process of diffusion the interstitially dissolved Cu(Ag) atoms would combine with the nearby Sn-vacancy and further annihilate the vacancy,thereby reducing the self-diffusion of Sn.