Characterization of non-stoichiometric hydration and the dehydration behavior of sitafloxacin hydrate

Sitafloxacin (STFX) hydrate is a non-stoichiometric hydrate. The hydration state of STFX hydrate varies non-stoichiometrically depending on the relative humidity and temperature, though X-ray powder diffraction (XRPD) of STFX hydrate was not affected by storing at low and high relative humidities. The detailed properties of crystalline water of STFX hydrate were estimated in terms of hygroscopicity, thermal analysis combined with X-ray powder diffractometry, crystallography and density functional theory (DFT) calculation. STFX hydrate changed the water contents continuously and reversibly from an equivalent amount of dihydrate through that of sesquihydrate depending on the relative humidity at 25°C. Thermal analysis and X-ray powder diffraction (XRPD) simultaneous measurement also revealed that STFX hydrate dehydrated into a hydrated state equivalent to monohydrate by heating up to 100°C, whereas XRPD patterns were slightly affected. This indicated that the crystal structure of STFX hydrate was retained at the dehydration level of monohydrate. Single-crystal X-ray structural analysis showed that two STFX molecules and four water molecule sites were contained in an asymmetric unit. STFX molecules formed a channel structure where water molecules were included. At the partially dehydrated state, at least two of four water molecules were considered to be disordered in occupancy and/or coordinates. Insight into the crystal structure of STFX hydrate stored at low and high relative humidities and geometry of the hydrogen bond were helpful to estimate the origin of non-stoichiometric hydration of STFX hydrate.     

New cholestane glycosides from the leaves of Cordyline terminalis

Four new cholestane glycosides (1-4) were isolated from the leaves of Cordyline terminalis (Agavaceae). The structures of the new compounds were determined on the basis of spectroscopic analysis and a few chemical transformations followed by chromatographic and spectroscopic analyses.     

Formulation study on retinoic acid gel composed of iota-carrageenan, polyethylene oxide and Emulgen® 408

In the present study, all-trans retinoic acid (RA) gels formulated with various compositions of polyethylene oxide (Emulgen?) and iota-carrageenan (ι-CG) were prepared and their physicochemical properties were evaluated. The compression energy, which is the work required to compress the product through a fixed distance, increased with increasing amount of ι-CG or Emulgen?. The adhesion energy and displacement decreased with increasing amount of ι-CG or Emulgen? due to the progression of gel formation. From the results of the sensory tests, the properties of RA gels such as adhesiveness, gel strength and spreadability seemed to be adjustable depending on the condition of skin by varying the components of RA gels. Through photostability study, the expiration date and storage conditions of RA gels were determined as "4°C for 28?d with no exposure to light."     

Sesquiterpene lactone glycosides from the roots of Ferula varia

Seven new sesquiterpene lactone glycosides (1-7) were isolated from the H2O-soluble fraction from the MeOH extract of the roots of Ferula varia. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations of compounds 1 and 2 were determined by modified Mosher's method.     

Novel method for constructing a large-scale design space in lubrication process by using bayesian estimation based on the reliability of a scale-up rule

A reliable large-scale design space was constructed by integrating the reliability of a scale-up rule into the Bayesian estimation without enforcing a large-scale design of experiments (DoE). A small-scale DoE was conducted using various Froude numbers (X(1)) and blending times (X(2)) in the lubricant blending process for theophylline tablets. The response surfaces, design space, and their reliability of the compression rate of the powder mixture (Y(1)), tablet hardness (Y(2)), and dissolution rate (Y(3)) on a small scale were calculated using multivariate spline interpolation, a bootstrap resampling technique, and self-organizing map clustering. A constant Froude number was applied as a scale-up rule. Experiments were conducted at four different small scales with the same Froude number and blending time in order to determine the discrepancies in the response variables between the scales so as to indicate the reliability of the scale-up rule. Three experiments under an optimal condition and two experiments under other conditions were performed on a large scale. The response surfaces on the small scale were corrected to those on the large scale by Bayesian estimation using the large-scale results and the reliability of the scale-up rule. Large-scale experiments performed under three additional sets of conditions showed that the corrected design space was more reliable than the small-scale design space even when there was some discrepancy in the pharmaceutical quality between the manufacturing scales. This approach is useful for setting up a design space in pharmaceutical development when a DoE cannot be performed at a commercial large manufacturing scale.     

Wide-band dereverberation method based on multichannel linear prediction using prewhitening filter

Several dereverberation algorithms have been studied. The sampling frequencies used in conventional studies are typically 8–16 kHz because their main purpose is preprocessing for improving the intelligibility of speech communication and articulation for automatic speech recognition. However, in next-generation communication systems, techniques to analyze and reproduce not only semantic information of sound but also more high-definition components such as spatial information and directivity will be increasingly necessary. To decompose these sound field characteristics with high definition, a dereverberation algorithm that is useful at high sampling frequencies is an important technique to process sound that includes high-frequency spectra such as musical sounds. The LInear-predictive Multichannel Equalization (LIME) algorithm is a promising dereverberation method. Using the LIME algorithm, however, a dereverberation signal cannot be solved at high sampling frequencies when the source signal is colored, such as in the case of speech and sound of musical signals. Because the rank of the correlation matrix calculated from such a colored signal is not full, the characteristic polynomial cannot be calculated precisely. To alleviate this problem, we propose preprocessing of all input signals with filters to whiten their spectra so that this algorithm can function for colored signals at high sampling frequencies.     

One-nucleon removal cross-sections for 17, 19C and 8, 10B

One-neutron removal cross-sections ( ) of ^{17, 19}C in various targets at about 900 MeV/nucleon, and one-proton removal cross-sections ( ) of ^{8, 10}B at about 1400 MeV/nucleon were measured using the fragment separator FRS at GSI. A significant increase of for ¹⁹C compared to its neighbors was observed. The same behavior was found for for the neutron-deficient nucleus ⁸B compared to the stable isotope ¹⁰B. These results support a one-neutron halo structure in ¹⁹C and a one-proton halo in ⁸B. Received: 26 July 2000 / Accepted: 11 January 2001     

Enhanced Adsorption Capacity and Photo-Catalytic Oxidative Activity of Dyes in Aqueous Medium by Hydrothermally Treated Titania Pillared Clay

Titania pillared montmorillonite clay was prepared by two different routes viz. 1) conventional ion exchange method and 2) modified method wherein the post hydrothermal treatment after ion-exchange was employed. The influence of the post hydrothermal treatment on the textural properties of titania-pillared clays was studied. The calcined clay was characterized by different physico-chemical techniques such as XRD, EDX, low temperature (77 K) nitrogen adsorption and UV-Vis diffuse reflectance spectroscopy. The content of pillared titania remained unchanged irrespective of the method of preparation. The method of preparation and severity of the conditions employed for the hydrothermal treatment resulted in alteration of the crystallinity and crystallite size of the anatase. The changes in the average pore diameter was found to comensurate with the changes in crystallite size of anatase phase. The increase in total pore volume as a function of the severity of the post hydrothermal treatment resulted in the decrease in micropore volume. The severity of the post hydrothermal treatment governed the extent of the blue shift in UV-Vis DRS spectra.The behaviour of titania pillared clays in adsorptive capacity and in photo-catalytic oxidation of methylene blue and victoria pure blue in aqueous medium was studied as a function of their physico-chemical characteristics. The titania pillared clays prepared by post hydrothermal route has shown enhanced adsorption capacity and photo-catalytic oxidation.     

Tetra‐n‐butyl­ammonium bis­(1,2‐dimercaptoethene‐1,2‐dicarbo­nitrilato‐S,S′)­nickel(III)

The crystal structure of the title compound, (C₁₆H₃₆N)[Ni(C₄N₂S₂)₂], shows stacking of the dimerized anions, surrounded by columns of cations.     

On thermal convection between two coaxial square containers inclined by forty five degrees

This paper is concerned with flow visualization, velocity, streakline, and heat transfer measurements on thermal convection between two coaxial square containers inclined by forty five degrees. It is found that there is no critical Rayleigh number for the onset of thermal convection in the test section. There appear two great circulations, which are symmetrical with respect to the diagonal vertical plane of the two coaxial square containers. Received on 18 June 1997