Molecular Properties of Propranolol Hydrochloride Prepared as Drug-Resin Complexes

Drug-resin complexes, as well as physical dispersions, containing varying contents of propranolol were prepared. The molecular properties of samples were investigated by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and infrared (IR) spectroscopy. In addition, the USP paddle method was used to determine the release behavior of drug from various formulations prepared from the samples. The data from DSC and XRPD indicated that the molecular state of drug in the complexes was amorphous, whereas that in the physical dispersions exhibited the crystalline state of pure drug. These results suggested that the molecule of drug prepared as drug-resin complexes was monomolecularly dispersed in the resin bead. The IR study provided evidence that demonstrated the interaction between the drug and resin in the complexes. The release behavior of drug from the complexes was governed by the cross-linkage structure and equilibrium treatment of drug exchange of resin.     

The Physicochemical Characteristics of Freeze-Dried Scutellarin-Cyclodextrin Tetracomponent Complexes

ABSTRACT

In an effort to improve the solubility of the insoluble drug scutellarin, a novel complexation of scutellarin with β-cyclodextrin (β-CD) was studied. Tetracomponent freeze-dried complex was prepared with scutellarin, β-CD, Hydroxypropyl Methylcellulose (HPMC), and triethanolamine. To confirm complex formation, complex was characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction, and differential scanning calorimetry (DSC). Phase-solubility analysis suggested the soluble complexes having 1:1 stoichiometry. The β-CD solubilization of scutellarin could be improved significantly by combining water-soluble polymer and pH adjuster. Comparing the binary, ternary solid systems with tetrary systems, tetracomponent freeze-dried complex showed the best effect of solubilization. A maximal solubility of scutellarin (23.65 mg/ml) was achieved with tetracomponent freeze-dried complex, up to 148-fold increase over scutellarin solubility in water, and the solubility of scutellarin is 15.35 ug/ml (up to 6-fold) in simulated gastric fluid.     

Some Physicochemical Properties of Mefenamic Acid

Mefenamic acid is a problematic drug in granulation, tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surfaces. In most cases, the specifications of a drug by the pharmacopoeia include identification and purity, but they do not describe the physicochemical drug properties precisely. To characterize the mefenamic acid particle size, surface area measurements, X-ray pattern, differential scanning calorimetry (DSC), wettability, crystal habit, and compression behavior of different batches from two manufacturers were investigated. Due to larger particle size and better wettability, mefenamic acid of Il Yang type was easier to handle in a granulation process. The compression behavior of both types was nearly the same, although particle size, crystal habit, and wettability were very different.     

Properties of (0.5−x)Zn-xFe2O3-0.5P2O5 glasses

Experimental determination of the properties of less studied zinc-iron-phosphate glasses was investigated. Glasses of the general composition (50−x)ZnO-xFe₂O₃-50P₂O₅, mol%, with x=0, 10, 20, 30 and 40, was chosen for these investigations. These studies included, glass forming, glass density, thermal expansion coefficient, dilatometric softening temperature, an initial test of chemical durability and vibrational properties. It is shown that an Fe/P ratio of the compositions at about 0.6 and 0.8 and the O/P ratio at 3.4 and 3.8 could be considered as chemically durable phosphate candidates.     

Solubility of Solid Dispersions of Pizotifen Malate and Povidone

We analyzed the physicochemical characteristics of solid dispersions of pizotifen malate and povidone (Kollidon 12) at different proportions; we used X-ray diffraction, infrared spectrometry, and differential scanning calorimetry (DSC) and tested the solubility of the solid dispersions in equilibrium. The results were compared with findings for physical mixtures with the same proportions. A solid dispersion with a drug proportion of 16%–17% formed a eutectic mixture. Solubility of pizotifen malate increased with the proportion of drug in the solid dispersion up to a drug:polymer ratio of 40:60. The hydrotropic effect of the polymer also favored solubility: In physical mixtures, this effect was greatest at a drug:polymer ratio of 10:90; solubility at this proportion was equal to that of the solid dispersion at the same proportion.     

Solubility of solid dispersions of pizotifen malate and povidone

We analyzed the physicochemical characteristics of solid dispersions of pizotifen malate and povidone (Kollidon 12) at different proportions; we used X-ray diffraction, infrared spectrometry, and differential scanning calorimetry (DSC) and tested the solubility of the solid dispersions in equilibrium. The results were compared with findings for physical mixtures with the same proportions. A solid dispersion with a drug proportion of 16%-17% formed a eutectic mixture. Solubility of pizotifen malate increased with the proportion of drug in the solid dispersion up to a drug:polymer ratio of 40:60. The hydrotropic effect of the polymer also favored solubility: In physical mixtures, this effect was greatest at a drug:polymer ratio of 10:90; solubility at this proportion was equal to that of the solid dispersion at the same proportion.     

Stability of the dry proton conductor CsHSO4 in hydrogen atmosphere

With an objective to assess the suitability of the dry proton conductor cesium hydrogen sulfate (CsHSO₄) as an electrolyte for fuel cells, its chemical stability in H₂ atmosphere in presence of the electrocatalyst Pt/C has been investigated. X-ray diffraction and differential scanning calorimetric (DSC) data indicate that CsHSO₄ decomposes to Cs₂SO₄ and H₂S at 150 °C in H₂ atmosphere when it is mixed with Pt/C catalyst, while it is quite stable under identical conditions in the absence of the Pt/C catalyst. Although thin composite membranes (∼80 μm) prepared with poly(vinylidene fluoride) and CsHSO₄ exhibit high proton conductivity at 150-200 °C that is adequate for fuel cell applications, development of compatible non-platinum alloy or transition metal oxide catalysts is needed before CsHSO₄ could be considered as an electrolyte for fuel cells. Also, processing procedures need to be optimized to obtain dense, gas impermeable membranes suitable for fuel cell applications.     

Crystal structure, thermal analysis and IR spectroscopic investigation of (C6H9N2)H2XO4 (X = As, P)

Crystals of 2-amino-4-methylpyridinium dihydrogenmonoarsenate (C₆H₉N₂)H₂AsO₄ and 2-amino-4-methylpyridinium dihydrogenmonophosphate (C₆H₉N₂)H₂PO₄ have been prepared and grown at room temperature. These materials are isotypic with the following unit cell dimensions (C₆H₉N₂)H₂AsO₄: a = 12.4415(5) Å, b = 6.8224(3) Å, c = 11.3524(5) Å, Z = 4, V = 963.60(6) Å³; (C₆H₉N₂)H₂PO₄: a = 12.4410(9) Å, b = 6.7165(3) Å, c = 11.3417(5) Å, Z = 4, V = 925.09(10) Å³. The common space group is Pnma. The structure of these compounds has been determined by X-ray data collection on single crystals of (C₆H₉N₂)H₂AsO₄ and (C₆H₉N₂)H₂PO₄. Due to the strong hydrogen-bond network connecting the H₂XO₄ groups, the anionic arrangement must be described as a linear organization. The chains composed by the macroanion spread along the b-direction, approximately centered by x = 0 and 1/2. All atoms of the structure, except one oxygen atom, are located in the mirror planes situated at y = 1/4 and 3/4, imparting an internal mirror symmetry to the anionic and the cationic entities. The linear macroanions are crossed by organic cations lying in mirrors perpendicular to the b-direction; this atomic arrangement is then described by a three-dimensional network of hydrogen bonds, built up by two types, O–HO bonds inside the chains and N–HO bonds linking adjacent chains. The thermal properties of both compounds are investigated as well as the IR properties supported by group theoretical analyses.     

Effects of thermal annealing on the optical,spectroscopic, and structural properties of tris (8-hydroxyquinolinate) gallium films grown on quartz substrates

In this study we report the optical, spectroscopic, and structural properties of vacuum deposited tris (8-hydroxyquinolinate) gallium film upon thermal annealing in the temperature range from 85 °C to 255 °C under a flowing nitrogen gas for 10 min. The optical UV–vis–NIR and luminescence spectroscopy measurements were performed to estimate the absorption bands, optical energy gap (E_g), and photoluminescence (PL) of the films. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques were used to probe the spectroscopic and structural nature of the films. We show that, by annealing the films from 85 °C to 235 °C, it is possible to achieve an enhanced absorption and increased photoluminescence to five times stronger than that of the pristine film. The PL quenching at 255 °C was attributed to the presence of plainer chains allow easy going for excitons to a long distance due to the crystalline region formation of α-Gaq3 polymorph. The reduction in E_g and infrared absorption bands upon annealing were referred to the enhancement in π–π interchain interaction and conformational changes by re-arrangement of the Gaq3 quinolinate ligands, respectively. Stokes shift for the films were observed and calculated. From the differential scanning calorimetry, DSC measurements, higher glass transition temperature was observed for Gaq3 (T_g = 182 °C) compared to that of Alq3 (T_g = 173 °C), which suggests the existence of stronger dipolar interaction in Gaq3 due to the Ga³⁺ cation effect, in comparison to that of Alq3.     

Preparation of irregular mesoporous hydroxyapatite

An irregular mesoporous hydroxyapatite (meso-HA), Ca₁₀(PO₄)₆(OH)₂, is successfully prepared from Ca(NO₃)₂·4H₂O and NH₄H₂PO₄ using surfactant cetyltrimethyl ammonium bromide (CTAB) as template. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results reveal that the positive head of CTAB is assembled on the surface precipitated HA and much NH₄⁺ is enclosed in precipitated HA before calcination. Field scanning electron microscope (FSEM) reveals that there exist many interconnected pores throughout the HA reticular skeleton. Nitrogen adsorption–desorption experiment exhibits a mesoporous material type IV curve, and pore size distribution calculated from the desorption branch of the isotherms based on Barrett–Joyner–Halenda (BJH) model shows that most pores throughout the HA reticular skeleton are sized at about 40 nm, but the pores are not uniform on the whole, owning to decomposition of the “organic” CTAB templating structures and ammonium salt enclosed in the precipitated HA. The specific surface area of irregular meso-HA is calculated to be 37.6 m²/g according to the Brunauer–Emmett–Teller (BET) equation. Moreover, after polylactic acid/meso-HA (PLA/meso-HA) composites degraded 12 weeks in normal saline at 37 °C, the interconnected pores throughout the HA skeleton were enlarged and sized in micron degree, which resemble trabecular bone structure very much.     

Spectroscopic and thermal behavior of ZnHg(SCN)4

The synthesis and purification of zinc mercury thiocyanate, ZnHg(SCN)₄ (ZMTC), are described. The identity of the synthesized compound was characterized by elemental analysis, X-ray powder diffraction, infrared, Raman, and UV/Vis/NIR transmission spectra. The thermal stability and thermal decomposition of ZMTC crystal were investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The intermediates and final products of the thermal decomposition were identified by X-ray powder diffraction (XRPD).     

Quantifying low amorphous or crystalline amounts of alpha-lactose-monohydrate using X-ray powder diffraction, near-infrared spectroscopy, and differential scanning calorimetry

Efficient and accurate quantification of low amorphous and crystalline contents within pharmaceutical materials still remains a challenging task in the pharmaceutical industry. Since X-ray powder diffraction (XRPD) equipment has improved in recent years, our aim was 1) to investigate the possibility of substantially lowering the detection limits of amorphous or crystalline material to about 1% or 0.5% w/w respectively by applying conventional Bragg Brentano optics, combined with a fast and simple evaluation technique; 2) to perform these measurements within a short time to make it suitable for routine analysis; and 3) to subject the same data sets to a partial least squares regression (PLSR) in order to investigate whether it is possible to improve accuracy and precision compared to the standard integration method. Near-infrared spectroscopy (NIRS) and differential scanning calorimetry (DSC) were chosen as reference method. As model substance, alpha lactose monohydrate was chosen to create calibration curves based on predetermined mixtures of highly crystalline and amorphous substance. In contrast to DSC, XRPD and NIRS revealed an excellent linearity, precision, and accuracy with the percent of crystalline amount and a detectability down to about 0.5% w/w. Chemometric evaluation (partial least squares regression) applied to the XRPD data further improved the quality of our calibration.     

聚全氟乙丙膜电子束引发预辐射接枝AA和SSS制备阳离子交换膜的性能

利用电子束引发预辐射接枝技术,在聚全氟乙丙烯(FEP)膜上接枝丙烯酸(AA)和对苯乙烯磺酸钠(SSS)两单体,制备出一种含羧酸基团和磺酸基团的阳离子交换膜,接枝率越高,接枝膜的吸碱性能越好。差示量热扫描及X射线衍射测试表明,接枝膜结晶度随接枝率的升高而降低。这是接枝膜中FEP组份的“结晶变形”及接枝链对晶区的“稀释作用”综合影响的结果。     

Crystallization kinetics and densification of YAG nanoparticles from various chelating agents

Yttrium aluminium garnet (YAG, Y₃Al₅O₁₂) nanoparticles were prepared using sonochemical sol-gel method with three different chelating agents and the effect of crystallization kinetics was investigated with differential scanning calorimetry-thermogravimetry (DSC-TG). The activation energy values of crystallization for the as-synthesized YAG nanoparticles using citric acid (CA), glycine (G) or a mixture of citric acid-glycine (CA-G), as chelating agents were found to be 160.5, 142.2 and 140.4 kJ mol⁻¹ and the corresponding Avarami constants were 2.2, 2.1 and 1.9, respectively. Samples produced with the mixed chelating agent under sonification, could be crystallized to single phase YAG nanoparticles (10-65 nm) after annealing at 1100 °C. Pellets made from the annealed YAG particles could be sintered to a relative density greater than 99% at 1500 °C with a grain size of 4.5 μm, made up of secondary particles formed from primary nano-crystals within the grains. Grain size and relative density increased with different chelating agents from CA to G and CA-G in the increasing order when YAG samples were sintered. Grain growth and densification occurred at a relatively low temperature of 1500 °C as compared to over 1800 °C in solid-state reactions.     

Thermal Behavior of Ursodeoxycholic Acid in Urea: Identification of Anomalous Peak in the Thermal Analysis

The objective of this study was to clarify the thermal behavior of ursodeoxycholic acid (UDCA) in mixtures with urea. Physical mixtures of UDCA and urea in various ratios were prepared, and the thermal analysis of these sample mixtures was investigated using conventional differential scanning calorimetry (DSC) and variable-temperature powder X-ray diffractometry (VTXRD). The hot-stage microscopy (HSM) and powder X-ray diffractometry (PXRD) were used as complementary techniques. From the DSC results of all sample mixtures, it was found that there was no endothermic peak at the melting temperature of intact UDCA crystals. The DSC thermograms of each ratio showed only the endothermic peak at about 136°C due to the melt of urea and the anomalous endothermic peak at about 155°C-157°C. The VTXRD study revealed that the crystals of urea completely disappeared at a temperature of 140°C. At this temperature, it was identified that the VTXRD pattern obtained was of UDCA crystals. The crystalline peaks gradually decreased in intensity at a temperature of 150°C. When the temperature was up to 160°C, the identical crystalline peaks of UDCA crystals completely disappeared. It was concluded that the anomalous endothermic peak at 155°C-157°C was the peak due to the dissolution of UDCA crystals in the surrounding melted urea.     

Facile synthesis of MOF-5 structure with large surface area in the presence of benzoyl peroxide by room temperature synthesis

In this study, for the first time, the uniform cylindrical MOF-5-BPO (Zn₄O(BDC)₃(H₂O)·0.5ZnO, BDC = 1,4-benzenedicarboxylate, BPO = benzoyl peroxide) crystals with large Brunauer–Emmett–Teller (BET) surface area (3210.2 m² g⁻¹) was successfully synthesized by room temperature synthesis in the presence of BPO using zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) as the zinc source. The pore volumes of MOF-5-BPO materials prepared with different concentrations of BPO were 0.84–1.07 cm³ g⁻¹, higher than that of MOF-5-NP (0.68 cm³ g⁻¹, Zn₄O(BDC)₃(H₂O)₃·2ZnO) and MOF-5-H₂O₂ (0.84 cm³ g⁻¹, Zn₄O(BDC)₃(H₂O)₂·2ZnO, H₂O₂ = hydrogen peroxide). The addition of the peroxides created new pores, which possessed the same diameters as the existing ones, thus increased the pore volume of the product. The concentration of BPO was critical for the pore texture of MOF-5-BPO. Moreover, MOF-5-BPO could store 1.24 wt% hydrogen at 77 K and 100 kPa. Thus, this study points out some information for one to realize the influence of the peroxides over MOF-5 structure and promises the potentiality of large-scale production of MOF-5 structure with large surface area.     

X-Ray Diffraction and Electron Microscopy in the Polymorphism Study of Ondansetron Hydrochloride

Using different techniques, we studied the possible formation of ondansetron polymorphs. Ondansetron is a carbazol antiemetic that acts as a competitive, selective inhibitor of 5-HT₃ serotonin receptors. The polymorphs were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results suggest that the compounds are not true crystallographic polymorphs, but instead are the product of physical structural changes in the drug, which would be of interest pharmaceutically.     

Some physicochemical properties of mefenamic acid

Mefenamic acid is a problematic drug in granulation, tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surfaces. In most cases, the specifications of a drug by the pharmacopoeia include identification and purity, but they do not describe the physicochemical drug properties precisely. To characterize the mefenamic acid particle size, surface area measurements, X-ray pattern, differential scanning calorimetry (DSC), wettability, crystal habit, and compression behavior of different batches from two manufacturers were investigated. Due to larger particle size and better wettability, mefenamic acid of Il Yang type was easier to handle in a granulation process. The compression behavior of both types was nearly the same, although particle size, crystal habit, and wettability were very different.     

离子束辅助沉积制备TaN薄膜的X射线衍射分析

利用离子束辅助沉积技术制备TaN薄膜，并对其进行X射线衍射分析。掠入射的X射线衍射分析得出：离子束辅助沉积制备的TaN薄膜是面心立方结构，晶格常数a为0．4405nm。根据X射线衍射分析，用屈服强度表征的TaN薄膜的显微硬度为16～20GPa，与文献上报道的显微硬度值接近。离子束辅助沉积制备的TaN薄膜宏观内应力较小，且都为压应力。晶粒尺寸大约在10nm左右，随着注入离子能量的增加，薄膜晶粒尺寸有长大的趋势。