Optimization of l‐arginine purification from Corynebacterium crenatum fermentation broth

l ‐Arginine has many special physiological and biochemical functions, with wide applications in the food and pharmaceutical industry. Few studies on the purification of l ‐arginine from fermentation broth have been conducted; however, none of them were systematic enough for industrial scale‐up. Therefore, it is necessary to develop a highly efficient and systematic process for the purification of l ‐arginine from fermentation broth. In this study, we screened out a cation exchange resin, D155, having high exchange capacity, high selectivity, and easy elution capacity, and analyzed its adsorption isotherm, thermodynamics, and kinetics using different models. Further, the process parameters of fixed‐bed ion exchange adsorption and elution were optimized, and the penetration curve during the operation was modeled. Based on the fixed‐bed ion‐exchange parameters, a 30‐column continuous ion‐exchange system was designed, and the flow velocity in each zone was optimized. Finally, to obtain a high purity of l ‐arginine, the purification tests were conducted using anion exchange resin 711, and an l ‐arginine yield of 99.1% and purity of 98.5% was obtained. This effective and economical method also provides a promising strategy for separation of other amino acids from the fermentation broth, which is of great significance to the l ‐arginine fermentation industry.     

Photo-stimulated long-lasting phosphorescence in Mn-doped zinc borosilicate glasses

In addition to long-lasting phosphorescence (LLP), photo-stimulated long-lasting phosphorescence (PSLLP) was also observed in Mn²⁺-doped zinc borosilicate glasses (ZSBM). When the bright red LLP induced by the irradiation of a ultraviolet (UV) lamp with λ_max=254 nm disappeared, the glass could re-emit this phosphorescence under the stimulation of lower energy light ranging from about 300 to 800 nm, while this phenomenon is not present without the pre-irradiation. The re-emitted phosphorescence was considerably bright and persistent after the removal of the stimulation light, hence called PSLLP. This PSLLP consists of two steps: the re-capture of the electrons photo-released from deep traps during the stimulation and the LLP process following the removal of the stimulation light. We demonstrated optical storage by using the ZSBM glass.     

Fast and sensitive liquid chromatography/electrospray mass spectrometry method to study ocular penetration of EDL‐155, a novel antitumor agent for retinoblastoma in rats

Our group has used the tetrahydroisoquinoline derivative EDL‐155 to treat glioblastoma in animal models and it is currently being evaluated in the treatment of ocular cancers. The purpose of this study was to develop a rapid and sensitive liquid chromatography and tandem mass spectrometry (LC‐MS/MS) method to study the plasma and vitreous humor disposition of EDL‐155 in rats. Animals received a single periocular injection of EDL‐155 (20 mg/kg). Animals were sacrificed at specified times (5, 60, 120, 240 and 360 min) and plasma and vitreous humor samples were obtained. EDL‐155 was isolated by protein precipitation and the extracts were analyzed by reversed‐phase high‐pressure liquid chromatography (HPLC) with MS/MS detection. A structurally similar analog was used as internal standard (IS). The chromatographic run time was 3.5 min per injection. The mass spectrometer was operated in positive‐ion, multiple reaction monitoring (MRM) mode. The mass transitions monitored were m/z332.2 → 167.2 (EDL‐155) and m/z391.2 → 200.2 (IS). The lower limit of quantification (LLOQ) was 0.1 ng/ml in both vitreous humor and plasma. The method was validated for selectivity, linearity, accuracy and precision in rat vitreous humor and partially validated for accuracy and precision in rat plasma. The ion suppression, recovery and stability of the analyte in the biological matrix were also tested. The assay was rapid, sensitive and robust enough to support EDL‐155 ocular penetration studies in a rodent model of intraocular cancer. Application of this method revealed that EDL‐155 was rapidly passed into the vitreous humor following periocular administration. Further, vitreous humor exposure exceeded systemic exposure by approximately sevenfold. High local concentrations coupled with minimal systemic exposure supports further testing of EDL‐155 as localized therapy for intraocular cancers. Copyright © 2009 John Wiley & Sons, Ltd.     

Blowing of silica microforms on silicon carbide

Silicon carbide ceramics have great potential for use in harsh environment applications, however many technical challenges still need to be addressed, including high temperature stability. The oxidation of SiC in air up to temperatures of 2053 K was conducted and resulted in the formation of a thermally grown silica scale that does not prove to be protective for very high temperature applications because of its rapid degradation. Examination of the oxide scale using scanning electron microscopy revealed the presence of striking features formed in a manner analogous to conventional glass blowing techniques. These features occurred for oxidation temperatures of at least 1773 K. The interfacial reaction between SiC and the oxide scale is responsible for the production of gases that must somehow escape. If the viscosity of the silica scale is low enough then it can be deformed freely by this pressure buildup.     

Liquid chromatography-electrospray tandem mass spectrometric assay suitable for quantitation of YM155, a novel small-molecule survivin suppressant, in dog plasma

This paper describes a sensitive and selective liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of the novel survivin suppressant YM155, 1-(2-methoxyethyl)-2-methyl-4,9-dioxo-3-(pyrazin-2-ylmethyl)-4,9-dihydro-1H-naphtho[2,3-d]imidazolium, which is developed for the treatment of solid tumors. This method uses a liquid-liquid extraction from 0.25 mL of dog plasma. LC separation was carried out on a Genesis Silica column (50 mm x 3.0 mm i.d.) at a flow-rate of 0.5 mL/min. Compounds were eluted using a mobile phase of 5 mm ammonium acetate and 0.1% formic acid in water-0.1% formic acid in acetonitrile, 17:83 (v/v). MS/MS detection was carried out with an MDS-Sciex API3000 triple quadrupole mass spectrometer in positive electrospray ionization mode. The standard curve was linear from 0.05 to 50 ng/mL (r > or = 0.9968). The lower limit of quantitation was 0.05 ng/mL. Good intra- and inter-day assay precision (within 7.4% RSD) and accuracy (within +/-12.3%) were obtained. The extraction recovery was 66.2%. The method was successfully applied to preclinical pharmacokinetic studies in dogs.     

Effect of method of preparation on photophysical properties of Rh-B impregnated sol-gel hosts

Rhodamine-B (Rh-B) impregnated sol-gel samples have been prepared using two different methods - mentioned as the dope and dip methods. Two types of dye impregnated samples were prepared using the dope method and one type using the dip method. A comparative study of photophysical properties of the three types of samples were carried out with the lapse of time of preparation up to about an year. The two types of samples prepared by dope method showed degradation in absorption/fluorescence properties with the lapse of time whereas no such degradation was observed with those samples prepared by dip method. The change in the absorption/fluorescence properties of Rh-B in dope samples has been associated with the increasing acid environment during sol-gel-xerogel transitions resulting in conversion of molecular form from cation to weakly fluorescent higher protonated form of Rh-B. On the other hand, Rh-B in dip samples have very stable absorption/fluorescence properties with high fluorescence quantum yield value equal to 0.98(±0.1). On the basis of a comparative study of the three types of Rh-B impregnated samples, Rh-B dipped samples were found to have the best performance and may be useful as laser active materials in solid state dye lasers.     

Measurement of transition quadrupole moments of high-spin states in the N=74 isotones Pr, Ce and La

The Doppler-Shift Attenuation Method has been used to extract transition quadrupole moments of high-spin bands in the N=74 isotones ¹³³Pr, ¹³²Ce and ¹³¹La, produced in the ³⁷Cl + ¹⁰⁰Mo reaction. The results appear to be configuration dependent and, for ¹³³Pr and ¹³²Ce, the involvement of Ω=1/2 νh_9/2 and νf_7/2 intruder orbitals appears to enhance the collectivity at high spin (I>25 ).     

颈动脉超声联合CT和血清miR-124、miR-155对颈动脉狭窄患者继发性脑梗的风险预测价值

本文探讨了颈动脉超声检查联合CT和血清微小RNA-124(miR-124)、微小RNA-155(miR-155)对颈动脉狭窄患者继发性脑梗的风险预测价值。以43例颈动脉狭窄患者为颈动脉狭窄组,正常志愿者43例为正常组,用RT-PCR法检测miR-124、miR-155表达,采用颈动脉超声检查颈动脉狭窄,采用CT检查颈部血管。结果显示,与正常组相比,颈动脉狭窄组miR-124、miR-155表达升高(P<0.05)。与超声、CT检查相比,超声检查联合CT检查颈动脉狭窄准确率、诊断价值较高(P<0.05)。本研究认为,颈动脉超声、CT、miR-124、miR-155对颈动脉狭窄的诊断价值较高,且可用于预测继发性脑梗的风险,预测价值较为理想。     

Effects of composition and catalyst on the optical properties of ZrO2-based Ormosil films

FTIR spectroscopy measurements were performed to investigate zirconia-based Ormosil thin films. Samples synthesized with a sol-gel technique were prepared starting from 3-glycidoxypropil-trimethoxysilane (GLYMO) and zirconium(IV)-propoxide (Zr-OPr). Acetic or nitric acid were used as a catalyst. The effects induced by the Zr content and the catalyst type on the mid-infrared spectra of the sol-gel hybrid films were studied and a detailed assignment of the vibrational absorption bands is presented. The thermal evolution of the hybrid systems was also followed by monitoring the release of the organic groups, the thickness, and refractive index changes by means of FTIR, diffuse reflectance spectroscopy, and ellipsometry.