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Crystalline Materials (crystalline + material)
Selected AbstractsSynthesis and Stereochemical Aspects of 2,6-Disubstituted Perhydroazulenes , Core Units for a New Class of Liquid Crystalline MaterialsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2006Zakir Hussain Abstract A novel approach for the synthesis of cis/trans -fused perhydroazulenes 13,19 is reported. The stereochemistry of the derivatives of carbene addition products 9a,c/20,22, of the 2,6-disubstituted perhydroazulenes 12a,c/23,25, and that of compounds 26,27 has been studied by single-crystal X-ray crystallography. The hydrogenation of the tropylidene to the perhydroazulene skeleton under various conditions is described. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Colloidal-Crystal-Assisted Patterning of Crystalline MaterialsADVANCED MATERIALS, Issue 13 2010Cheng Li Abstract Colloidal crystals have shown great potential as versatile templates for the fabrication of patterned micro- and nanostructures with complex architectures and novel properties. The patterning of functional crystalline materials in two and three dimensions is essential to the realization of their applications in many technologically important fields. This article highlights some recent progress in the fabrication of 2D and 3D patterned crystalline materials with the assistance of colloidal crystals. By combining a bioinspired synthetic strategy based on a transient amorphous phase with a colloidal-crystal templating method, unique 3D ordered macroporous (3DOM) calcite single crystals can be created. Moreover, patterned arrays of regular ZnO nanopillars with controlled size, shape, and orientation can be fabricated via a facile wet chemical approach by using masks derived from monolayer colloidal crystals (MCC). [source] Complex Iridium(III) Salts: Luminescent Porous Crystalline Materials,ANGEWANDTE CHEMIE, Issue 7 2010Matteo Mauro Komplexe mit Ausstrahlung: Eine neue Klasse poröser Materialien beruht auf nichtkovalent verknüpften lumineszierenden Iridiumkomplexen. Komplexpaare mit unterschiedlichen Emissionsfarben und komplementären Ladungen bilden Komplexsalze. Die kristallinen Materialien enthalten 3D-poröse Motive, und ihre Emissionsfarbe lässt sich durch Lösungsmitteleinschluss oder selektives Löschen einer Komponente beeinflussen. [source] Synthesis, characterization of an unusual crystalline material with tartrateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008Yongbing Gu Abstract An exploration of the cobalt-tartrate system under hydrothermal conditions, has led to the isolation of crystalline framework {Co2(H2tar)2]·2H2O}n (1) (H2tar = tartrate dianion). Single-crystal X-ray analyses reveal that it crystallizes in the orthorhombic space group P21212. a = 11.0924(11) Å, b = 7.8517(8) Å, c = 9.0171(9) Å, , = 90°. A dinuclear CoII unit is formed via two different coordinated tartrate molecules. Further these units are united together through two bridging carboxylate groups of hexa-coordinated H2tar ligands to form a 2D grid layer, which exhibits a typical (6,3) topological network. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis, characterization and crystal structure of a porous crystalline materialCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2008Chun-Sheng Zhou Abstract An exploration of the nickel-malate-bpp system under hydrothermal conditions, has led to the isolation of a novel framework {[Ni(Hmal)(bpp)]·5H2O}n (1) (Hmal = malate dianion, bpp = 1,3-bi(4-pyridyl)propane). Single-crystal X-ray analyses reveal that it crystallizes in the orthorhombic space group Pccn. a = 21.141(3) Å, b = 10.4028(16) Å, c = 19.250(3) Å. The Ni(II) ions are linked into an extended helical chain via Hmal molecules. Further these chains are united together through the bridging bpp to form a 3D porous framework, which exhibits an unusual NbO-type topological network. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Lithium and Potassium Amides of Sterically Demanding AminopyridinesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2004Natalie M. Scott Abstract The reaction of Grignard compounds of 1-bromo-2,4,6-diisopropylbenzene (1) or 1-bromo-2,6-dimethylbenzene (2), formed in situ, with 2,6-dibromopyridine in the presence of a catalytic amount of [(dme)NiBr2] (dme = 1,2-dimethoxyethane) and tricyclohexylphosphane (1:2 ratio) leads to the corresponding monoarylated bromopyridines. These bromopyridines undergo Pd-catalysed aryl amination (Buchwald,Hartwig amination) with 2,6-diisopropylaniline giving rise to (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine (Ap*H) and (2,6-diisopropylphenyl)[6-(2,6-dimethylphenyl)pyridin-2-yl]amine (Ap,H) (Ap = aminopyridinate). Deprotonation of Ap*H in diethyl ether using BuLi results (after workup in hexane) in a colourless crystalline material. X-ray structural analysis reveals it to be a monomeric three-coordinate lithium aminopyridinate. In toluene solution, an equilibrium between [(Ap*Li)2] (in excess at room temperature) and [Ap*Li(OEt2)] (prominent at low temperature) is observed. Reaction of Ap,H with BuLi in diethyl ether gives rise to [Ap*LiAp*Li(OEt2)]. Deprotonation of Ap*H and Ap,H using KH leads to [Ap*K]n and [Ap,K],, respectively. [Ap,K], is a rare example of a crystalline organometallic polymer, as determined by X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Thermal analysis of merino wool fibres without internal lipidsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007M. Martí Abstract Merino wool is made up of cuticle and cortical cells held together by the cell membrane complex (CMC), which contains a small amount of internal lipids (IWL) (1.5% by mass). IWL have been extracted from wool on account of their considerable dermatological interest owing to their proportion of ceramides. IWL have been extracted by different methods and solvents, methanol and acetone at laboratory and pilot plant levels. Thermal analysis of these extracted wool fibers is presented using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG provides a measurement of the weight loss of the sample as a function of time and temperature. DSC gives information about possible structure modification of extracted wool fibers. Thermoporometry was applied to evaluate the pore size distribution of extracted wool fibers. The results showed that the extraction process increased the pore size distribution and the cumulated pore volume, which is consistent with some changes in the extracted wool CMC. Extracted fiber becomes more hydrophilic and absorbs a large amount of water. We can conclude that the lipid extraction of wool produced no relevant changes in the crystalline fraction when extracted with acetone. However, part of the amorphous keratin material was extracted with methanol, the rest of the crystalline material becoming more stable. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 545,551, 2007 [source] Characterization of the Triacylglycerol Crystal Formation in Adipose Tissue During a Vehicle CollisionJOURNAL OF FORENSIC SCIENCES, Issue 4 2007Barbara H. Stuart Ph.D. Abstract:, The unusual appearance of crystalline fat structures was observed during the postmortem examination of a motor vehicle accident victim. The crystal structures were characterized using Fourier transform infrared spectroscopy and x-ray diffractometry. The structures were found to be made of triacylglycerols, a dominant lipid structure found in human adipose tissue, capable of forming various polymorphic structures. The morphology of the crystalline material was found using both techniques to be predominantly the ,, form of triacylglycerols. The accelerated growth of such triacylglycerol morphology has been observed as a result of shear stresses in other studies involving edible fats. As a result of the findings of this study, it is proposed that increased shear forces may be responsible for the formation of the unusual fat structure found in the victim. An understanding of the effect of forces on the structure of body fat in high-impact collisions can potentially assist in verifying a high-velocity impact. [source] Solubility and degradation of polyhydroxyalkanoate biopolymers in propylene carbonateAICHE JOURNAL, Issue 6 2010Christopher W. J. McChalicher Abstract New biobased materials and chemicals require different processing strategies than petroleum-derived commodities. The extraction and recovery of polyhydroxyalkanoate (PHA) biopolymers from the residual cellular biomass is particularly difficult because the polymer is accumulated within the cell. PHAs have low solubility in many classical polymer solvents and are most often dissolved using undesirable chlorinated solvents. The solubility kinetics is greatly diminished when these polymers are highly crystalline. Here, 1,2-propylene carbonate is used to dissolve highly crystalline polyhydroxybutyrate at ambient pressures and moderate temperatures. We have used kinetic studies of the dissolution of the crystalline material to determine the energy barrier for dissolution of the system. Further, the degradation of polyhydroxybutyrate and similarly prepared PHA block copolymers were studied during this extraction process using molecular weight characterization by gel permeation chromatography. Finally, we have used these findings to extract PHA block copolymers from dried biomass at the bench scale. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Determination of amorphous content in the pharmaceutical process environmentJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2007Marja Savolainen The amorphous state has different chemical and physical properties compared with a crystalline one. Amorphous regions in an otherwise crystalline material can affect the bioavailability and the processability. On the other hand, crystalline material can function as nuclei and decrease the stability of an amorphous system. The aim of this study was to determine amorphous content in a pharmaceutical process environment using near infrared (NIR) and Raman spectroscopic techniques together with multivariate modelling tools. Milling was used as a model system for process-induced amorphization of a crystalline starting material, ,-lactose monohydrate. In addition, the crystallization of amorphous material was studied by storing amorphous material, either amorphous lactose or trehalose, at high relative humidity conditions. The results show that both of the spectroscopic techniques combined with multivariate methods could be applied for quantitation. Preprocessing, as well as the sampling area, was found to affect the performance of the models. Standard normal variate (SNV) transformation was the best preprocessing approach and increasing the sampling area was found to improve the models. The root mean square error of prediction (RMSEP) for quantitation of amorphous lactose using NIR spectroscopy was 2.7%, when a measuring setup with a larger sampling area was used. When the sampling area was smaller, the RMSEPs for lactose and trehalose were 4.3% and 4.2%, respectively. For Raman spectroscopy, the RMSEPs were 2.3% and 2.5% for lactose and trehalose, respectively. However, for the optimal performance of a multivariate model, all the physical forms present, as well as the process environment itself, have to be taken into consideration. [source] Thermally stable porous supramolecular frameworks based on the metal and ,,, stacking directed self-assembly of 2,6-pyridyldicarboxylic acid bis-4-pyridylamideJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2003Juan C. Noveron Abstract We report the formation of two thermally stable supramolecular structures based on 2,6-pyridyldicarboxylic acid bis-4-pyridylamide (PyI) and bis(hexafluoroacetylacetonato)manganese(II) that exhibits a microporous structure with cavities bearing hydrogen bonding motifs that can enclathrate acetone and methanol molecules via well-positioned hydrogen bonding interactions. Single-crystal x-ray diffraction in combination with thermogravimetric analysis and X-ray powder diffraction (XRPD) studies were utilized to study the structure and thermal behavior of trans -[Mn(hfacac)2(PyI)2]·2(CH3)2CO (1) and trans -[Mn(hfacac)2(PyI)2]·2CH3OH (2). Our studies indicated that 1 and 2 are isostructural with respect to their supramolecular assembly and trap solvent molecules along the crystallographic b direction via the inwardly directed hydrogen bonding motifs of the PyI component. These solvent molecules can be thermally removed to generate a crystalline material with micropores bearing hydrogen bonding rich sites within an overall supramolecular matrix similar to 1 and 2. The removal of the guest solvent molecules is reversible and can be followed with XRPD. Copyright © 2003 John Wiley & Sons, Ltd. [source] Alveolar soft part sarcoma of the endometrium with expression of CD10 and hormone receptors,APMIS, Issue 7 2007Case Report Alveolar soft part sarcoma (ASPS) is a rare tumor of uncertain histogenesis, mainly localized in the extremities. ASPS originating in the uterine corpus is quite rare; only eight such cases have been reported in the literature. We here present another case of ASPS found in the endometrium in a 50-year-old woman. Metastatic malignant tumor, including ASPS from other organs, was excluded by physical examination and imaging modalities. Thallium 201 was only localized in the uterus. The tumor showed characteristic histological features of ASPS: alveolar architecture with fibrovascular septa and abundant eosinophilic granular cytoplasm with periodic acid-Schiff-positive crystalline material. Diffuse nuclear immunoreactivity for TFE3, a marker recently reported to be specific for ASPS, further supported the diagnosis of ASPS. Interestingly, this tumor was negative for myogenic markers, but positive for CD10, progesterone receptor, and estrogen receptor. These immunohistochemical results and the tumor location suggest a possible link between endometrial stromal cells and the development of this tumor. [source] A case of tenosynovial chondromatosis with tophus-like deposits,APMIS, Issue 9 2004Case report Tenosynovial chondromatosis has not been well recognized because of its rarity, but it is clinically important because of its high rate of recurrence. We report here a case of tenosynovial chondromatosis with deposits of crystalline material that appeared to be sodium urate (gouty tophi). A 37-year-old Japanese man was admitted because of a hard mass in his left third finger. He had undergone surgery at the same anatomical site four and seven years previously. The roentgenogram revealed a soft tissue mass in the flexor aspect of the proximal phalanx. At operation, the tumor was found to have arisen in the tendon sheath. Histopathological examination showed that the tumor was composed of well-defined, multiple, cartilaginous nodules that were surrounded by tenosynovial tissue. A few of the nodules were calcified. The chondrocytes had mild atypia, and were immunopositive for S-100 protein. A diagnosis of tenosynovial chondromatosis was made. The nodules also contained crystalline deposits, which bore a histological resemblance to gouty tophi. We were unable to define the exact nature of these deposits even by transmission electron microscopy and electron roentgenographic microanalysis. Crystalline deposits in chondromas of soft tissue have been reported but not in tenosynovial chondromatosis. [source] Image-based crystal detection: a machine-learning approachACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2008Roy Liu The ability of computers to learn from and annotate large databases of crystallization-trial images provides not only the ability to reduce the workload of crystallization studies, but also an opportunity to annotate crystallization trials as part of a framework for improving screening methods. Here, a system is presented that scores sets of images based on the likelihood of containing crystalline material as perceived by a machine-learning algorithm. The system can be incorporated into existing crystallization-analysis pipelines, whereby specialists examine images as they normally would with the exception that the images appear in rank order according to a simple real-valued score. Promising results are shown for 319,112 images associated with 150 structures solved by the Joint Center for Structural Genomics pipeline during the 2006,2007 year. Overall, the algorithm achieves a mean receiver operating characteristic score of 0.919 and a 78% reduction in human effort per set when considering an absolute score cutoff for screening images, while incurring a loss of five out of 150,structures. [source] Oxime Carbonates: Novel Reagents for the Introduction of Fmoc and Alloc Protecting Groups, Free of Side ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2010Sherine N. Khattab Abstract Fmoc and Alloc protecting groups represent a consistent alternative to classical Boc protection in peptide chemistry. The former was established in the last decades as the ,-amino protecting group of choice, whereas the latter allows a fully orthogonal protection strategy with Fmoc and Boc. Usually, the introduction of the Fmoc and Alloc moieties takes place through their halogenoformates, azides, or activated carbonates. This rather simple reaction is accompanied by several side reactions, specially the formation of Fmoc/Alloc dipeptides and even tripeptides. The present work describes new promising Fmoc/Alloc-oxime reagents, which are easy to prepare, stable, and highly reactive crystalline materials that afford almost contaminant-free Fmoc/Alloc-amino acids in high yields by following a conventional procedure. Amongst the Fmoc-oxime derivatives, the N -hydroxypicolinimidoyl cyanide derivative (N -{[(9H-fluoren-9-yl)methoxy]carbonyloxy}picolinimidoyl cyanide) gave the best results for the preparation of Fmoc-Gly-OH, which is the most predisposed to give side reactions. The same Alloc-oxime analogue afforded the preparation of Alloc-Gly-OH in good yield, purity, and extremely low dipeptide formation, as analyzed by reverse-phase HPLC and NMR spectroscopy. [source] Colloidal-Crystal-Assisted Patterning of Crystalline MaterialsADVANCED MATERIALS, Issue 13 2010Cheng Li Abstract Colloidal crystals have shown great potential as versatile templates for the fabrication of patterned micro- and nanostructures with complex architectures and novel properties. The patterning of functional crystalline materials in two and three dimensions is essential to the realization of their applications in many technologically important fields. This article highlights some recent progress in the fabrication of 2D and 3D patterned crystalline materials with the assistance of colloidal crystals. By combining a bioinspired synthetic strategy based on a transient amorphous phase with a colloidal-crystal templating method, unique 3D ordered macroporous (3DOM) calcite single crystals can be created. Moreover, patterned arrays of regular ZnO nanopillars with controlled size, shape, and orientation can be fabricated via a facile wet chemical approach by using masks derived from monolayer colloidal crystals (MCC). [source] Acceleration of Calcite Kinetics by Abalone Nacre Proteins,ADVANCED MATERIALS, Issue 22 2005G. Fu Abalone shell nacre proteins act as surfactants to promote ion attachment at calcite steps, causing acceleration of the molecular-scale kinetics of calcite crystal growth. The proteins modify the shape of growing calcite (see Figure) through step-specific interactions, even though the proteins are larger than the atomic-scale steps. Understanding of crystal-growth control by interactions with proteins may give better control of new crystalline materials. [source] A simple and low-cost solution for the automation of X-ray powder diffractometers with chart recorder outputJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2006M. Jayaprakasan X-ray powder diffraction is an established method for the qualitative identification of crystalline materials and their quantitative analysis. The new generation of X-ray diffraction systems are based on expensive digital/embedded control technology and computer interfaces. Yet many laboratories use conventional manual-controlled systems with XY strip-chart recorders. Since the output spectrum is a strip chart (hard copy), raw data, essential for structural and qualitative analysis, are not readily available for further analysis. Upgrading to modern computerized diffractometers is very expensive. The proposed automation design described here is intended to enable the conventional diffractometer user to collect, store and analyze data quickly. The design also improves the resolution by five times compared with the conventional setup. For the automation, a PC add-on card has been designed to control and collect the timing and intensity counts from the conventional X-ray diffractometer, and suitable software has been developed to collect, process and present the X-ray diffraction data for both qualitative and quantitative analysis. Moreover, a major advantage of this design is that it does not warrant any physical modification of the hardware of the conventional setup; it is simply an extension to enhance the performance of collecting raw data with a higher resolution at desired intervals/timings. [source] Properties of soy protein isolate/poly(vinyl alcohol) blend "green" films: Compatibility, mechanical properties, and thermal stabilityJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Jun-Feng Su Abstract Blend films from nature soy protein isolates (SPI) and synthetical poly(vinyl alcohol) (PVA) compatibilized by glycerol were successfully fabricated by a solution-casting method in this study. Properties of compatibility, mechanical properties, and thermal stability of SPI/PVA films were investigated based on the effect of the PVA concentration. XRD tests confirm that the SPI/PVA films were partially crystalline materials with peaks of 2, = 20°. And, the addition of glycerol will insert the crystalline structure and destroy the blend microstructure of SPI/PVA. Differential scanning calorimetry (DSC) tests show that SPI/PVA blend polymers have a single glass transition temperature (Tg) between 80 and 115.0°C, which indicate that SPI and PVA have good compatibility. The tension tests show that SPI/PVA films exhibit both higher tensile strength (,b) and percentage elongation at break point (P.E.B.). Thermogravimetric analysis (TGA) and water solubility tests show that SPI/PVA blend polymer has more stable stability than pure SPI. All the results reflect that SPI/PVA/glycerol blend film provides a convenient and promising way to prepare soy protein plastics for practical application. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Model development for semicontinuous production of ethylene and norbornene copolymers having uniform compositionAICHE JOURNAL, Issue 3 2009Shaojie Liu Abstract Terminal and penultimate models for controlling copolymer composition distribution (CCD) in ethylene and norbornene (NB) copolymerization were developed by taking into account the variation of active site concentration with the initial comonomer ratio. The models were validated by batch polymerization experimental data. The terminal model gave better correlation with the composition data whereas the penultimate model had a better fit to the rate data. The terminal model was then used to design NB feeding policies in semicontinuous processes for targeted CCD profiles. Based on the model results, a series of ethylene-NB copolymers with various NB contents were prepared. With the same NB content, the semicontinuous process produced a uniform composition, whereas the batch process yielded broad CCD. The batch samples had lower Tg values and broader transition ranges, even yielded crystalline materials. In contrast, the semicontinuous samples overcame the disadvantages. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Informatic calibration of a materials properties database for predictive assessment of mechanically activated disordering potential for small molecule organic solidsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2009Yannan Lin Abstract The potential for small molecule organic crystalline materials to become disordered as a result of high shear mechanical processing was investigated. A data-driven model was generated from a database of critical materials properties, which were expected to correlate with the potential of a small molecule organic crystalline solid to become fully disordered by the application of mechanical energy. The model was compared with a previously published disordering model based on fundamental thermodynamic relationships. Samples of 23 crystalline solids were subjected to extensive comminution under controlled temperature conditions; powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) were used to confirm disordering. Logistic regression was used to investigate the significance of each materials property with respect to the prediction of disordering potential. Seven materials properties (glass transition temperature, melting temperature, heat of fusion, crystallographic density, Young's modulus, molar volume and attachment energy) were identified as having a significant correlation with the potential for material disordering. Stepwise multivariate logistic regression was used to further assess the correlation between disordering potential and each of the seven properties. A linear probability model based on two materials properties (glass transition temperature and molar volume) was developed for the prediction of disordering potential. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:2696,2708, 2009 [source] Process induced disorder in crystalline materials: Differentiating defective crystals from the amorphous form of griseofulvinJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Tao Feng Abstract This research investigates milling induced disorder in crystalline griseofulvin. Griseofulvin was subjected to cryogenic milling for various lengths of time. For comparison, the amorphous form of griseofulvin was also prepared by the quench melt method. Different analytical techniques were used to study the differences between the cryomilled, amorphous and crystalline forms of the drug. Cryogenic milling of griseofulvin progressively reduces the crystallinity of the drug by inducing crystal defects, rather than amorphous materials. Raman analysis provides evidence of structural differences between the two. The differences between the defective crystals produced by milling and the amorphous form are significant enough as to be measurable in their bulk thermal properties. Defective crystals show significant decrease in the heat of fusion as a function of milling time but do not exhibit a glass transition nor recrystallization from the amorphous form. Crystal defects undergo recrystallization upon heating at temperatures well below the glass transition temperature (Tg) in a process that is separate and completely independent from the crystallization of the amorphous griseofulvin, observed above Tg. Physical mixtures of defective crystals and amorphous drug demonstrate that the thermal events associated with each form persist in the mixtures, unaffected by the presence of the other form. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 3207,3221, 2008 [source] The effect of water to ethanol feed ratio on physical properties and aerosolization behavior of spray dried cromolyn sodium particlesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2005Kambiz Gilani Abstract Cromolyn sodium (CS) was spray dried under constant operation conditions from different water to ethanol feed ratios (50:50,0:100). The spray dried CS samples were characterized for their physicochemical properties including crystallinity, particle size distribution, morphology, density, and water/ethanol content. To determine quantitatively the crystallinity of the powders, an X-ray diffraction (XRD) method was developed using samples with different crystallinity prepared by physical mixing of 100% amorphous and 100% crystalline CS materials. The aerodynamic behavior of the CS samples was determined using an Andersen Cascade Impactor (ACI) with a Spinhaler® at an air flow of 60 L/min. Binary mixtures of each spray dried CS powder and Pharmatose® 325, a commercial ,-lactose monohydrate available for DPI formulations, were prepared and in vitro aerosol deposition of the drug from the mixtures was analyzed using ACI to evaluate the effect of carrier on deposition profiles of the spray dried samples. CS spray dried from absolute ethanol exhibited XRD pattern characteristic for crystalline materials and different from patterns of the other samples. The crystallinity of spray dried CS obtained in the presence of water varied from 0% to 28.37%, depending on the ratio of water to ethanol in the feed suspensions. All samples presented different particle size, water/ethanol content, and bulk density values. CS particles spray dried from absolute ethanol presented uniform elongated shape whereas the other samples consisted mainly of particles with irregular shape. Overall, fine particle fraction increased significantly (p,<,0.01) with decreasing d50% and water and ethanol content of spray dried CS samples. Significant difference (p,<,0.01) in deposition profiles of the drug were observed between corresponding carrier free and carrier blended formulations. The difference in deposition profiles of CS aerosolized from various spray dried samples were described according to the particle size, shape, and water/ethanol contents of the powders. The results of this study indicate that enhanced aerosol performance of CS can be obtained by spray drying of the drug from suspensions containing ,87.5% v/v ethanol. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1048,1059, 2005 [source] Combining two structural techniques on the micrometer scale: micro-XAS and micro-Raman spectroscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2007V. Briois X-ray absorption and Raman spectroscopies are complementary in the sense that both give very precise information about the local structure of a sample, both are not restricted to crystalline materials, and in both cases the volumes of the material probed are similar. The X-ray technique has the advantage of being element- and orbital-selective, and sensitive to orientational effects owing to polarization selection rules. In many cases, however, its analysis can present some ambiguity. Combining the two techniques on a micrometer scale could therefore be a very powerful method structurally. In this paper the experimental set-up developed at the LUCIA beamline and its application to a natural mineral are described. [source] Backscattering X-ray standing waves in the XUV regionJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2001T. M. Grehk It is demonstrated that Bragg reflection of XUV radiation can be used to study structural properties of crystalline materials with large unit cells. A standing-wave field is formed in a layered TiSe2 single crystal for a near-backscattering geometry (, = 88.5°). The partial electron yield is measured as a function of photon energy across the (001) Bragg reflection condition (h,, 1033,eV) and its characteristic modulation is compared with the results derived from dynamical diffraction theory in the two-wave approximation. The data reveal a large amount of disorder along the c -axis. [source] Ba(Mg,Zr,Ta)O3:Nd3+ fine-grained ceramics: a novel laser-gain material with disordered structure for high-power laser systemsLASER PHYSICS LETTERS, Issue 4 2009A.A. Kaminskii Abstract Nd3+ -ion doped Ba(Mg,Zr,Ta)O3 ceramics is introduced as a new gain crystalline materials for lasers and laser amplifiers. By pumping laser-diode radiation at 300 K its CW stimulated emission at 1.0754 ,m wavelength was recorded. Some optical, spectroscopic and mechanical properties were measured as well. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Observation of nonlinear lasing ,(3) -effects in highly transparent nanocrystalline Y2O3 and Y3Al5O12 ceramicsLASER PHYSICS LETTERS, Issue 1 2004A.A. Kaminskii Abstract Multi-wavelength nonlinear parametric ,(3) -effects were observed in highly transparent Y2O3 and Y3Al5O12 nanocrystalline ceramics under picosecond pumping at 300 K. All recorded Stokes and anti-Stokes components in the visible and near IR were identified and attributed to the stimulated Raman scattering active vibration modes of these novel optical and laser-host crystalline materials. For both materials, the steadystate first-Stokes Raman gain coefficient was estimated at a wavelength of around 1 ,m. (© 2004 by HMS Consultants. Inc. Published exclusively by WILEY-VCH Verlag GmbH & Co.KGaA) [source] Prediction of Microporous Aluminophosphate AlPO4 -5 Based on Resampling Using Partial Least Squares and Logistic DiscriminationMOLECULAR INFORMATICS, Issue 3 2010Miao Qi Abstract In this paper, Partial Least Squares (PLS) regression and Logistic Discrimination (LD) are employed to predict the formation of microporous aluminophosphate AlPO4 -5 based on the database of AlPO synthesis, which aims to provide a useful guidance to the rational synthesis of microporous materials as well as other inorganic crystalline materials. To deal with the problem of class imbalance, four guided resampling methods considering not only the between-class imbalance but also the within-class imbalance are proposed. Experimental results indicate that the presented methods are competent for predicting the formation of microporous aluminophosphate AlPO4 -5. Specially, compared with some existing resampling methods, our proposed resampling methods exhibit much better predictive results. [source] Development of CdSSe/CdS VCSELs for Application to Laser Cathode Ray TubesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2004K. P. O'Donnell Abstract This report summarises recent progress towards the realisation of Laser Cathode Ray Tube (LCRT) devices on the basis of II,VI semiconductors. Although such devices were demonstrated over 30 years ago, using bulk crystalline materials as the active media, practical lasers that operate at room temperature for extended periods of time are not yet readily available. We aim to overcome this roadblock by reducing the threshold power densities of working lasers. By embedding heterostructures, grown using metalorganic vapour phase epitaxy (MOVPE), within all-dielectric microcavities, the necessary threshold reductions can be made. The construction and testing of an exemplar device, based upon CdSSe/CdS (hex) multiple quantum wells, is described. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On the elastic contribution to crystal growth in complex environmentsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2005A. Gadomski Abstract Based on a number of experimental studies, we propose to consider how elastic interactions between a crystal and its surroundings change crystal growing conditions. To aim to do this, we analyze the influence of some nonequilibrium modification of the Gibbs,Thomson thermodynamic condition, prescribed at the crystal boundary, on some properties of a kinetic model of protein crystal growth in a mass-convection regime. Next, to draw the physical picture more realistically, we study the influence of a certain stochastic perturbation on the crystal growth rate. To fulfill the task we apply the description of crystal growth in terms of nonequilibrium thermodynamics at a mesoscopic level. The proposed model offers a quite comprehensive picture of the formation of modern organic crystalline materials such as non-Kossel crystals. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||||||||