Growth kinetics of CaF2 in a pH-stat fluidized-bed crystallizer

In this study, experiments were first conducted in a stirred vessel to establish the metastable region of calcium fluoride, using a pH-stat apparatus for controlling the pH value of solution. The effects of pH value on the solubility and metastable region were observed. Then, operating variables, including supersaturation, superficial velocity, pH value, seed size, and types of seed and solution, that influenced the crystal growth of the same system were investigated in a fluidized-bed crystallizer. The crystal growth rates were determined from the consumption rates of fluoride ions. The growth kinetics was explored by using the two-step growth model. The effectiveness factor was used to judge whether a controlling step was existing. The kinetics of crystal growth in a lean bed and a dense bed was also discussed.     

Solvothermal Syntheses and Magnetic Properties of Two New Coordination Polymers with Mixed Ligands

Two new coordination polymers, [Ni(H₂O)(BDC)(bpp)]_n ( 1 ) and [Co(mBDC)(bpp)]_n ( 2 ) (BDC = 1,4‐benzene dicarboxylate anion; bpp = 4,4′‐trimethylene dipyridine; mBDC = 1,3‐benzene dicarboxylate anion), were synthesized by solvothermal reaction and structurally characterized. Single crystal X‐ray diffraction showed that 1 consists of an inclined interpenetration of 1D nets generating an overall 3D entanglement and compound 2 of 1D chains. The luminescent and magnetic properties of both compounds in the solid state were also investigated. Crystal data: 1 : orthorhombic, Pnna; a = 18.3648(6), b = 13.6854(4), c = 16.2307(5) Å, V = 4079.3(2) ų, and Z = 8. Crystal data: 2 : triclinic, ; a = 8.6966(4), b = 10.1093(4), c = 11.8334(4) Å, α = 68.263(1)°, β = 82.895(1)°, γ = 78.370(1)°, V = 945.16(7) ų, and Z = 2.     

Unequal crossover recombination - population screening for PHOX2B gene polyalanine polymorphism using CE

Congenital central hypoventilation syndrome (CCHS) is a rare neurological disorder characterized by abnormal autonomic central nervous system control of breathing during sleep. Mutations in the paired-like homeobox 2B (PHOX2B) gene, including point mutation, frameshift, and polyalanine expansion, are associated with the pathogenesis of CCHS. In this study, PHOX2B mutations were analyzed in seven CCHS patients, their family members, and 1520 healthy individuals from the general population using CE to provide high sensitivity and resolution screening for the PHOX2B polyalanine polymorphism. Seven mutations in the PHOX2B gene, including two frameshift mutations and five polyalanine expansions in the 20-residue polyalanine tract, were identified. The various phenotypes observed in CCHS patients with PHOX2B mutations suggest that the size of the expansion allele is associated with the CCHS risk. In addition, significant differences were found in allele and genotype distributions between the healthy individuals. Alleles (GCN)(20) and (GCN)(15) had the highest population incidence rates of 94.84 and 4.51%, respectively, with the remaining alleles, (GCN)(13) and (GCN)(7), accounting for 0.59 and 0.06%, respectively. Therefore, it has been demonstrated that CE can be used to improve the detection of polyalanine expansions in the PHOX2B gene. The attractive alternative method is a promising tool for the detection of disorders involving trinucleotide repeat tracts.     

Characterization of pore structure in metal-organic framework by small-angle X-ray scattering

MOF-5-like crystals were studied by small-angle X-ray scattering (SAXS) to reveal, both quantitatively and qualitatively, their real structural details, including pore surface characteristics, pore shape, size distribution, specific surface area (SSA), spatial distribution, and pore-network structure. A combined SAXS and wide-angle X-ray scattering (WAXS) experiment was conducted to investigate the variation of the pore structure with the MOF-5 crystalline phase produced at different cooling rates. The SSA of the MOF-5 crystals synthesized herein spanned a broad range from approximately 3100 to 800 m2/g. The real pore structures were divided into two regimes. In regime I the material consisted mainly of micropores of radius approximately 8 A as well as mesopores of radius 120 approximately 80 A. The structure in regime II was a fractal network of aggregated mesopores with radius >or=32 A as the monomer, reducing SSA and hydrogen uptake capacity at room temperature. The two regimes can be manipulated by controlling the synthesis parameters. The concurrent evolution of pore structure and crystalline phase during heating for solvent removal was also revealed by the in-situ SAXS/WAXS measurement. The understanding of the impact of the real pore structure on the properties is important to establish a favorable synthetic approach for markedly improving the hydrogen storage capacity of MOF-5.     

Purification of deoxynivalenol from Fusarium graminearum rice culture and mouldy corn by high-speed counter-current chromatography

Deoxynivalenol (DON) is a mycotoxin produced by several Fusarium species and is toxic to a wide range of organisms, including human beings and livestock. To produce large amounts of pure DON for research purposes, a novel method using high-speed counter-current chromatography (HSCCC) was developed. Rice cultured with Fusarium graminearum and field mouldy corn infected by F. graminearum were extracted with methanol and found to contain 1.16 and 1.30 mg DON/g, respectively. The extracts were concentrated and then separated using a biphasic solvent system consisting of ethyl acetate-water (1:1, v/v). Collected fractions were analyzed by high-performance liquid chromatography (HPLC) and identified by congruent retention time and UV/vis spectrum and mass spectrometric data. Fractions containing DON were combined and freeze-dried. This method produced 116 mg and 65 mg DON with a purity of greater than 94.9% from 200 g of the rice culture and the mouldy corn, respectively. The HSCCC method had a recovery rate of DON at 88% from the crude extracts of both samples. This one-step purification method provided a simple and effective tool for obtaining a large amount of DON, an essential material for studies related to toxicology and detoxification of this mycotoxin.     

制备大直径无气泡聚苯乙烯空心微球

 高品质聚苯乙烯（PS）空心微球是惯性约束聚变（ICF）实验用多层塑料微球靶的重要芯轴,常由乳液技术制备。针对由乳液技术制备的PS微球壳壁内容易形成气泡而且大直径微球制备困难的问题,实验研究了对壳壁内存在的气泡以及消除方法和制备大直径PS微球的制备技术。     

Measurement of Titanium and Manganese K -shell Ionization Cross Sections by Electron Impact

报道了电子引起的钛、锰原子的Ｋ壳层电离截面实验值。实验中,采用了薄靶厚衬底技术,并将衬底中反射的电子对测量值的影响进行了修正。实验结果与其他文献报道的测量结果相吻合。最后,还将实验结果与Ｃａｓｎａｔｉ等人的经验公式进行了比较。     

An extended interaction oscillator based on a complex resonatorstructure

We report experimental investigation of a novel scheme for efficient interaction between a linear electron beam and an electromagnetic wave in a complex extended interaction structure. The structure of interest consists of a high R/Q, five-gap, coupled-cavity resonator that incorporates a coaxial section of a quarter plasma wavelength placed between the first and second cavities. In the coaxial section, beam and wave propagate in separate channels. The first cavity, strongly coupled to the other cavities through the wave channel of the coaxial section, serves as a buncher cavity. An inner channel running through the center conductor of the coaxial section provides a cutoff drift space for ballistic bunching of electrons, an effect that is shown to significantly enhance the interaction efficiency. Oscillation power of 2.2 kW at 16.6 GHz was demonstrated with an interaction efficiency of 30%. The total efficiency was further increased to 41% by incorporation of a two-stage depressed collector     

Artocarpol A,a Novel Constituent with Potent Anti‐inflammatory Effect,Isolated from Artocarpus rigida

A novel phenolic compound, artocarpol A ( 1 ), was isolated from the root bark of Artocarpus rigida and its structure determined by spectroscopic methods and by comparison with its diacetate derivative. Compound 1 strongly inhibited superoxide formation in phorbol 12‐myristate 13‐acetate (PMA) stimulated rat neutrophils in a concentration‐dependent manner with an IC₅₀ value of 13.7±0.7 μM . Compound 1 also showed a significant inhibitory effect on tumor necrosis factor‐α (TNF‐α) formation in lipopolysaccharide(LPS)‐stimulated RAW 264.7 cells.     

Two Novel and Anti‐Inflammatory Constituents of Artocarpus rigida

With the scope of our search for biologically active compounds, two new phenolic compounds, artocarpols G ( 1 ) and H ( 2 ), and two known compounds, rubraflavone C ( 3 ) and trans‐stilbene‐2,4,3′,5′‐tetrol, were isolated from the root bark of Artocarpus rigida. Their structures were determined by spectroscopic methods and comparison with data reported in the literature. Compound 4 , previously isolated from this plant, strongly inhibited in a concentration‐dependent manner the release of β‐glucuronidase and histamine from mast cell degranulation caused by compound 48/80, with IC₅₀ values of 10.9±1.4 and 13.2±0.6 μM , respectively. Compound 4 also showed a concentration‐dependent inhibitory effect on the formyl‐peptide‐stimulated superoxide anion formation in neutrophils with an IC₅₀ value of 26.0±5.6 μM .