Evaporation-condensation derived silicon carbide membrane from silicon carbide particles with different sizes

Silicon carbide ceramic is a promising membrane material because of the high corrosive and high temperature resistance, and the excellent hydrophility. Here, a silicon carbide ceramic membrane with both substrate layer and separate layer composed of pure silicon carbide phase was successfully prepared. The effect of particle size on the microstructure and properties was investigated. The substrates were prepared from three silicon carbide particles at 2200 ℃. With the content increase of fine particle, the average pore size increased from 5.6 μm to 14.1 μm; meanwhile, the flexural strength of the substrate increased from 14.1 MPa to 24.6 MPa. The separation layers were made from particles of 3.0 μm and 0.5 μm. When sintered at 1900 ℃, the separation layer formed pore network with homogeneous structure. Such silicon ceramic membrane can be used in harsh conditions, including high temperature wastewater and strongly corrosive wastewater.     

Comparative metabolism of [3H]psoralen and [3H]isopsoralen by black swallowtail (Papilio polyxenes Fabr.) caterpillars

The comparative fate of tritiated preparations of a linear furanocoumarin (psoralen) and an angular furanocoumarin (isopsoralen) was determined in last-instar caterpillars of the black swallowtail butterfly (Papilio polyxenes Fabr.). Oral administration of either furanocoumarin at 5 g/g is followed by rapid metabolism, primarily through oxidative cleavage of the furan ring, and the metabolites are rapidly excreted. Isopsoralen is, however, metabolized at a somewhat slower rate than is psoralen, and levels of unmetabolized isopsoralen in body tissues of the treated caterpillars are about three-fold higher. These data are compatible with the hypothesis that a reduced detoxification rate accounts at least in part for the susceptibility ofP. polyxenes caterpillars to the deleterious effect of isopsoralens.     

Fluidization characteristics of printed circuit board plastic particles with different sizes

The experiments were carried out in a fluidized bed of 56 mm in diameter and 1 600 mm in height to determine the fluidization characteristics of four sizes of printed circuit board plastic (PCBP) particles. It indicates that the fluidization characteristics of PCBP particles depend on the average size and particle type. 123 µm PCBP particles (1#), belonging to Geldart A group with strong viscous force, whose fluidization behaviours was similar to those of Geldart C, was difficult to fluidize. Whereas, 275 µm (2#), 354 µm (3#), and 423 µm (4#) PCBP particles, belonging to Geldart B, were fluidized smoothly. The bed collapsing process is composed of three stages: the bubble escaping stage, the sedimentation stage, and the solid consolidation stage. The collapsing process of 1# PCBP particle lasts 6 s or long. 2#, 3#, and 4# PCBP particles, Geldart group B particles, collapse process consists of the bubble escaping stage and the solid consolidation stage. The minimum fluidization velocities from modified Ergun Equation were agreement with experimental data for 2#, 3#, and 4# PCBP particles.     

N-甲基-3,3-二甲基螺[2H-吲哚-2,3-[3H]萘并[2,1-b][1,4]噁嗪]的微波合成与表征

以三乙胺为催化剂,1-亚硝基-2-萘酚和1,3,3,-三甲基-2-亚甲基吲哚啉为原料合成了N-甲基-3,3-二甲基螺[2H-吲哚-2,3,-[3H]萘并[2,1-b][1,4]噁嗪]。本反应在无溶剂下的微波反应,相比传统有机反应大大缩短了反应时间。并且探讨了反应温度、反应时间、催化剂用量对反应的影响。对产物进行了IR、~1HNMR、~(13)CNMR等表征,结果表明:反应温度150℃,反应10 min,可以获得较高产率的纯产物。     

Sedimentation and liquid fluidization of solid particles of different sizes and densities

The sedimentation and fluidization of particles of mixed sizes and different densities were studied. A new concept—the apparent porosity of suspensions—was introduced, on the basis of which equations have been developed that are capable of predicting the settling velocities of individual types of particles in a suspension containing mixtures of particles. The validity of these equations was tested against experimental data in both sedimentation and fluidization.     

Radiochemical Decomposition of lactosyl-6-[3H]-ceramide

Galactosyl-6-[³H] glucosyl ceramide was prepared by the sequential action of galactose oxidase and sodium borohydride-[³H] reduction. A water-soluble radioactive contaiminant appeared after a 2 month storage at −4 C. This was identified as lactose-[³H] by both chromatographic and carrier dilution techniques.     

3’-[辛基(2-甲基苯基)胺基]-6’-(2-甲基苯基)胺基-螺[异苯并呋喃-1(3H),9’-[9H]呫吨-3-酮的合成

以荧光素为原料经氯化、氨解、烷基化反应合成了性能优良的热敏品染料3’-[辛基(2-甲基苯基)胺基]-6’-(2-甲基苯基)胺基-螺[异苯并呋喃-1 (3H),9’-[9H]呫吨-3-酮,确定了最佳的合成路线,最终产品含量≥97％,在波长550nm处吸收值≤0.1.     

磁性灰粒在不同粒级气化灰渣中的分布特性

以气流床煤气化粗渣和细灰为原料,采用筛分和磁选的方法研究了磁性灰粒在不同粒级气化灰渣中的分布特性。结果表明：随着灰渣粒径的减小,在粗渣和细灰中,磁性灰粒的含量均呈现先升高后降低的趋势,磁性灰粒在粗渣中的含量高于细灰。粗渣中,磁性灰粒在0.5~0.25mm粒级中分布最多,该粒级神宁炉和GSP气化炉粗渣在粒度组成中的占比也最高,质量分数分别为38.42%和37.16%,各个粒级中磁性灰粒产率随粒径减小呈递增趋势;细灰中,磁性灰粒在0.074~0.045mm粒级中分布最多,而细灰粒度组成中的占比最高的却是大于0.25mm粒级,磁性灰粒产率在各个粒级都不高,呈现随粒径减小而升高的规律。气化过程中,磁铁矿会更多地富集在凝结团聚且高度玻璃化的大粒径粗渣中,粗渣和细灰中仍有相当量的含铁物相不显磁性。不同粒级煤气化灰渣中磁性灰粒的分布特性可为气化渣分级分质及高值化利用提供基础数据支撑和应用思路。     

Mechanical properties and morphologies of polypropylene with different sizes of glass bead particles

A commercial grade of isotactic polypropylene (PP) was used to study the mechanical properties and morphologies of the PP composites filled with four sizes of glass bead particles. The glass bead particles used were with average particle sizes of 15 μm (GB15), 10 μm (GB10), 5 μm (GB5), and 2.5 μm (GB2.5), respectively. It was clear that the glass bead size was an important factor on the determination of mechanical properties of the composites. As a whole, in view of the scatter in the data, under the condition of same filler content, the yield strength and impact strength of the composites filled with smaller glass bead particles was higher than those of the composites filled with bigger ones. And the flexural strength and modulus of the composites filled with GB10, GB5, or GB2.5 particles could be regarded as the same. The flexural strength and modulus of the composites filled with GB15 particles were higher than those of the composites filled with other three sizes of particles. Among four sizes of glass bead particles, GB2.5 had the best toughening effect to improve the impact strength of PP matrix. And the major toughening mechanism of the PP/GB2.5 composites was the pinning effect introduced by GB2.5. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Mechanical properties and morphologies of polypropylene with different sizes of calcium carbonate particles

Three polypropylene (PP) matrixes with different intrinsic toughness were used to study the morphologies and mechanical properties of PP filled with four sizes of calcium carbonate particles. PP1 was a homopolymer, PP2 was a propylene‐ethylene copolymer, and PP3 was a mixture of PP1 and PP2 (PP1:PP2 = 1:1, weight ratio). Calcium carbonate (CC25, CC4, CC1.8, and CC0.07) with an average particle size of 25, 4, 1.8, and 0.07 μm, respectively, was used. It was clear that the PP matrix and filler size had key effects on improvement of mechanical properties of PP matrix. For all three PP matrixes, the yield strength, the flexural strength and modulus of the composites filled with CC25, CC4, and CC1.8 could be regarded as the same. But the yield strength, the flexural strength and modulus of composites filled with CC0.07 were obviously lower than those of composites filled with other sizes of particles. Among four sizes of calcium carbonate particles, CC0.07 had the best toughening effect to improve the impact strength of PP matrix, and the toughening effect of CC0.07 was influenced by PP matrix. For all PP matrixes, only in the case of moderate matrix toughness (PP3 matrix), the composite could receive the highest extent of toughness increase (4.3 times that of matrix). With regard to all PP composites, the best combination of properties was PP2 nanocomposite filled with 20 wt% CC0.07. POLYM. COMPOS., 27:443–450, 2006. © 2006 Society of Plastics Engineers     

The biosynthesis of n-[2H7] fatty acids byArthrobacter globiformis from [U-2H15] octanoic acid

The principal fatty acids present whenArthrobacter globiformis is grown on a glycine medium free of normal fatty acids were found to be the C15 and C16 anteiso fatty acids; only a small amount of the normal fatty acids (C14 and C16) were present. Cells grown on the same medium but supplemented mented with 0.1 mg/ml [U-²H₁₅]octanoic acid were found to contain an increased amount of the normal fatty acids and these fatty acids were found to be labeled with 7 deuteriums. I concluded that the octanoic acid is degraded by β-oxidation in these cells to [U-²H₇] butyryl-CoA, which then competes with 2-methylbutyryl-CoA for the initiation of fatty acid biosynthesis.     

Dielectric and microwave absorption properties of FeSiAl/Al2O3 composites containing FeSiAl particles of different sizes

Here in, the effects of FeSiAl particle size on the dielectric and microwave absorption properties of FeSiAl/Al₂O₃ composites were studied. FeSiAl/Al₂O₃ composites containing 18–25 μm, 25–48 μm, and 48–75 μm FeSiAl particles were prepared by hot-pressed sintering based on uniformly mixed FeSiAl and Al₂O₃ powders. Results show that the real permittivity and the imaginary permittivity are significantly promoted with increasing FeSiAl particle size, which is ascribed to the enhanced interfacial polarization and conductance loss. In addition, the favorable matching impedance and suitable attenuation coefficient enabled the composite containing 25–48 μm FeSiAl powder to show a minimum reflection loss of ?34.4 dB at 11.7 GHz and an effective absorption bandwidth (<-10 dB) of 1.4 GHz in 11.0–12.4 GHz, when the thickness is 1.1 mm. By adjusting the thickness to 1.4 mm, the effective absorption bandwidth of the composite reaches a maximum value of 2.0 GHz in the 8.3–10.3 GHz range, indicating tunable, strong, and highly efficient microwave absorption performance.     

[~2H_3]-吗啡的合成及同位素丰度研究

为获取GC-MS或LC-MS分析中用作内标氘代[2H3]-吗啡对照品,建立了标题化合物的合成方法,成功合成了[2H3]-吗啡,并用1HNMR及13CNMR表征。用液质联用技术研究了同位素丰度,其中[2H3]-吗啡的丰度为99.19%。     

Superacidic FSO3H/HF catalyzed butane isomerization [1]

Superacid catalyzed isomerization of butane was studied. Highly efficient isomerization of butane to 2-methylpropane (isobutane) was achieved using fluorosulfuric acid containing up to 5% of hydrogen fluoride acting as a protic co-acid. The isomerization when carried out in excess FSO₃H at 21 ° C in a flow system gave 70% conversion to 2-methylpropane with generally less than 3% cracking. When 2-methylpropane was isomerized under similar conditions about 12% butane was formed. Attempted isomerization of pentane and hexane with prolonged reaction times in a static system results in predominant protolytic cleavage (cracking).     

Failure to demonstrate degradation of [4-14C] cholesterol to volatile hydrocarbons in rats and in human fecal homogenates

The inability of previous workers to recover completely the radioactivity from ingested [4-14C] cholesterol has led to the hypothesis that the colonic flora of some individuals degrade the sterol nucleus to volatile hydrocarbons, particularly CH4. In the present investigation, the production of radioactive volatiles was measured following incubation of [4-14C] cholesterol with 8 human fecal homogenates or after instillation of the labeled sterol into the cecum of 3 rats housed in a closed rebreathing system. Three of the 8 homogenates and each of the 3 rats produced copious CH4. However, analysis by combustion demonstrated no radioactivity above background in the volatile headspace of the homogenates or the gas space of the closed system housing the rats, indicating that less than 0.001% of the number 4 carbon of [4-14C] cholesterol could have been converted to volatile hydrocarbons. This study, therefore, provides no support for the concept that volatile products account for the incomplete recovery of ingested sterols observed in certain subjects. However, this hypothesis can not be excluded entirely until similar results are obtained with subjects who can be shown to degrade cholesterol.     

2-氟-9,10-亚甲二氧基-6[H]-[1]苯并吡喃并[4,3-b]喹啉的合成与表征

以6-氟-色满酮-4为原料，与6-氨基胡椒醛发生Friedǎnder合反应而得到新的喹啉衍生物2-氟-9，10-亚甲二氧基-6[H]-[1]苯并吡喃并〔4，3-b]喹啉，其结构经IR、^1HNMR、MS和元素分析确证。     

The essential oil fromTagetes minuta L. modulates the binding of [3H]flunitrazepam to crude membranes from chick brain

The hypothesis that the essential oil fromTagetes minuta L. can interact with biological membranes was investigated by assessing its ability of perturbing the binding of a benzodiazepine [flunitrazepam (FNTZ)] to crude membranes from chick brains. The essential oil fromT. minuta L. inhibited [³H]FNTZ specific binding to chick brain membranes. These values were obtained from the analysis of the saturation curve for the kinetic parameters: dissociation equilibrium constant (K_d)=2.47±0.32 nM, maximal binding (B_max)=556±5 fmoles/mg protein, and Hill coefficient (n)=1.00±0.07 in the absence, and K_d=6.73±1.4 nM, B_max=583±69 fmoles/mg protein, and n=1.02±0.08 in the presence of 29 μg/mL of essential oil. The essential oil could self-aggregate with a critical micellar concentration (CMC) of 60 μg/mL. The marked increase in [³H]FNTZ nonspecific binding starting at 60 μg of essence per mL was due to that phenomenon and revealed the ability of self-aggregated structures to interact with membranes. [³H]FNTZ specific binding decrement as a function of essence concentration cannot be ascribed merely to oil's micelles ability of trapping the lipophilic radioligand molecules, because the discontinuous behavior that characterizes a monomer-aggregate phase transition was not shown. Oil's components might behave as competitive inhibitors or allosteric modulators of FNTZ specific binding. However, their ability to increase FNTZ nonspecific binding at concentrations below oil's CMC suggests that this effect may be due to oil's partitioning into the lipid bilayer. This latter phenomenon would induce an increment in membrane fluidity and a change on FNTZ binding site toward a lower affinity conformation. Therefore, the essential oil components can interact with brain membranes either as monomers, by partitioning into the lipid bilayer, or as self-aggregated structures, through an adsorption to the membrane surface.     

Long Chain Fatty Acid Uptake In Vivo: Comparison of [125I]-BMIPP and [3H]-Bromopalmitate

Insulin resistance is characterized by increased metabolic uptake of fatty acids. Accordingly, techniques to examine in vivo shifts in fatty acid metabolism are of value in both clinical and experimental settings. Partially metabolizable long chain fatty acid (LCFA) tracers have been recently developed and employed for this purpose: [9,10-(3)H]-(R)-2-bromopalmitate ([(3)H]-BROMO) and [(125)I]-15-(rho-iodophenyl)-3-R,S-methylpentadecanoic acid ([(125)I]-BMIPP). These analogues are taken up like native fatty acids, but once inside the cell do not directly enter beta-oxidation. Rather, they become trapped in the slower processes of omega and alpha-oxidation. Study aims were to (1) simultaneously assess and compare [(3)H]-BROMO and [(125)I]-BMIPP and (2) determine if tracer breakdown is affected by elevated metabolic demands. Catheters were implanted in a carotid artery and jugular vein of Sprague-Dawley rats. Following 5 days recovery, fasted animals (5 h) underwent a rest (n = 8) or exercise (n = 8) (0.6 mi/h) protocol. An instantaneous bolus containing both [(3)H]-BROMO and [(125)I]-BMIPP was administered to determine LCFA uptake. No significant difference between [(125)I]-BMIPP and [(3)H]-BROMO uptake was found in cardiac or skeletal muscle during rest or exercise. In liver, rates of uptake were more than doubled with [(3)H]-BROMO compared to [(125)I]-BMIPP. Analysis of tracer conversion by TLC demonstrated no difference at rest. Exercise resulted in greater metabolism and excretion of tracers with approximately 37% and approximately 53% of [(125)I]-BMIPP and [(3)H]-BROMO present in conversion products at 40 min. In conclusion, [(3)H]-BROMO and [(125)I]-BMIPP are indistinguishable for the determination of tissue kinetics at rest in skeletal and cardiac muscle. Exercise preferentially exacerbates the breakdown of [(3)H]-BROMO, making [(125)I]-BMIPP the analogue of choice for prolonged (>30 min) experimental protocols with elevated metabolic demands.