Interpretation of gas residence time distributions in large airlift tower loop reactors

Gas-residence time distribution (RTD) response curves measured in a 23 m high pilot plant airlift tower loop reactor, which consisted of a riser, a special downcomer construction and at the top of the riser a large head. The measurements were evaluated by means of a deterministic dispersion model, which yielded the following particular parameters for the riser, downcomer and the head: Gas-Bo numbers, gas-mean residence times, gas holdups, liquid velocities, gas and liquid circulation times as well as a fraction of the large and small bubbles in a model medium (water) and during cultivation of baker's yeast.List of Symbols A cross section - Bo Bodenstein number - Bo _d (= l _d w _G,d /D _d ) - Bo _h (= l _h w _G,h /D _h ) - Bo _r (= l _r w _G,r /D _r ) - D longitudinal dispersion coefficient - E gas holdup - E(t) RTD-density function - L, l length parameter - q fraction of the gas throughput which is not recirculated (approximately equal to fraction of the large bubbles) - r fraction of the throughput which is recirculated (approximately equal to the fraction of the small bubbles) - t _c circulation time - t _cL liquid circulation time - t _c,L ^* liquid circulation time calculated from the measured w _Ld in the downcomer - V ^h hydrodynamical calculated gas-liquid volume - V _d ^h (=V _d+0.75/2 V _k ) - V _k ^h =(0.25V _k ) - V _r ^h = (V _r+0.75/2 V _k ) - V _L liquid volume - V _G dispersed gas volume - V _G ^* gas throughput at the gas distributor (given in m³/h) under standard conditions, 1 bar and 25°C) - V _G,d ^* gas throughput in downcomer (=V _G ^* ) - V _G,h ^* gas throughput in head (=V _G ^* ) - V _G,r ^* gas throughput in riser (V _G ^* (1+) - w _g gas velocity - w _G,rel relative gas velocity with respect to the liquid velocity w _L - w _G,d gas velocity in the downcomer (=w _G,rel –w _Ld ) - w _G,h gas velocity in the head (=w _G,rel ) (since wLh = o) - w _G,r gas velocity in the riser (=w _G,rel +w _Lr ) - w _L liquid velocity - w _L,d liquid velocity in the downcomer measured with mass flow meter - w _sg ·w _SL superficial gas and liquid velocities - first moment of the response curve - mean residence time Indices d downcomer - G gas phase - h head - L liquid phase - r riser - h hydrodynamic (upper position) Dedicated to the 65th birthday of Proffessor Fritz Wagner.The authors gratefully acknowledge the financial support by the Krupp Industrietechnik, Grevenbroich and the support of Pleser Co, Darmstadt. H. M. Rüffer thanks the Verband der Chemischen Industrie for a Fond der Chemie scholarship, and W. Liwei thanks the government of Lower Saxony for a graduate scholarship.     

Butanol Extract of Acanthopanax senticosus (Rupr. et Maxim.) Harms Alleviates Atherosclerosis in Apolipoprotein E-Deficient Mice Fed a High-Fat Diet

This study investigated the effect of butanol extract of AS (ASBUE) on atherosclerosis in apolipoprotein E-deficient (ApoE^−/−) mice. The mice were administered ASBUE (390 or 130 mg/kg/day) or rosuvastatin (RSV) via oral gavage for eight weeks. In ApoE^−/− mice, ASBUE suppressed the abnormal body weight gain and improved serum and liver biochemical indicators. ASBUE remarkably reduced the aortic plaque area, improved liver pathological conditions, and lipid metabolism abnormalities, and altered the intestinal microbiota structure in ApoE^−/− mice. In the vascular tissue of ASBUE-treated mice, P-IKKβ, P-NFκB, and P-IκBα levels tended to decrease, while IκB-α increased in high fat-diet-fed atherosclerotic mice. These findings demonstrated the anti-atherosclerotic potential of ASBUE, which is mediated by the interaction between the gut microbiota and lipid metabolism and regulated via the Nuclear Factor-kappa B (NF-κB) pathway. This work paves the groundwork for subsequent studies to develop innovative drugs to treat atherosclerosis.     

猫后内侧上雪氏区视神经元对运动棒反应的取向和方向特征

猫后内侧上雪区（ｐｏｓｔｅｒｏｍｅｄｉａｌｌａｔｅｒａｌｓｕｐｒａｓｙｌｖｉａｎａｒｅａ,ＰＭＬＳ）的绝大多数神经元（１７１／２００）对运动棒的取向调谐,６２％（１２４／２００）细胞的取向调谐宽度（半高波宽）小于９０°：按方向选择性和取向选择性可分辨出几类特征明显的细胞类型：１、强取向和强方向选择性细胞;２、强取向调谐的双向选择细胞;３、弱取向调谐的强方向选择细胞;４、无取向无方向选择性细胞;以及５、特征不明显的或中间类型细胞。它们与最近光学记录揭示的鹰猴中颞叶视区（ｍｉｄｄｌｅｔｅｍｐｏｒａｌｖｉｓｕａｌａｒｅａ,ＭＴ）的组织有很好的吻合。     

四川55种鱼生活史型的研究

四川５５种鱼生活史型的研究刁晓明,罗一兵李波（西南农业大学水产系,重庆６３０７１６）（重庆大学计算机系,６３００００）ＬｉｆｅＨｉｓｔｏｒｙＰａｔｔｅｒｎｓｏｆ５５ＦｉｓｈＳｐｅｃｉｅｓｉｎＳｉｃｈｕａｎ￥ＤｉａｏＸｉａｏｍｉｎｇ;ＬｕｏＹｉｂｉｎｇ...     

Complementing amino acid substitutions within loop 6 of the alpha/beta-barrel active site influence the CO2/O2 specificity of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase

Photosynthesis-deficient mutant 45-3B of the green alga Chlamydomonas reinhardtii contains a chloroplast mutation that causes valine-331 to be replaced by alanine within the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. This amino acid substitution occurs in loop 6 of the alpha/beta-barrel active site, three residues distant from catalytic lysine-334. The mutation reduces the specific activity of the enzyme and also reduces its CO2/O2 specificity factor by 42%, but the amount of holoenzyme is unaffected. In a previous study, an intragenic-suppressor mutation, named S40-9D, was selected that causes threonine-342 to be replaced by isoleucine, thereby increasing the CO2/O2 specificity of the mutant enzyme by 36%. To determine which other residues might be able to complement the original mutation, nine additional genetically independent revertants have now been analyzed. Another intragenic suppressor, represented by mutation S61-2J, causes glycine-344 to be replaced by serine. This change increases the CO2/O2 specificity of the mutant enzyme by 25%. Of the revertants recovered and analyzed, the mutant enzyme was improved only due to true reversion or by intragenic suppression mediated by substitutions at residues 342 or 344. Changes in the physical properties of the two pairs of complementing substitutions indicate that steric effects within loop 6 are responsible for the observed changes in the CO2/O2 specificity of the enzyme.     

Comprehensive profiling of accessible surface glycans of mammalian sperm using a lectin microarray

It is well known that cell surface glycans or glycocalyx play important roles in sperm motility, maturation and fertilization. A comprehensive profile of the sperm surface glycans will greatly facilitate both basic research (sperm glycobiology) and clinical studies, such as diagnostics of infertility. As a group of natural glycan binders, lectin is an ideal tool for cell surface glycan profiling. However, because of the lack of effective technology, only a few lectins have been tested for lectin-sperm binding profiles. To address this challenge, we have developed a procedure for high-throughput probing of mammalian sperm with 91 lectins on lectin microarrays. Normal sperm from human, boar, bull, goat and rabbit were collected and analyzed on the lectin microarrays. Positive bindings of a set of ~50 lectins were observed for all the sperm of 5 species, which indicated a wide range of glycans are on the surface of mammalian sperm. Species specific lectin bindings were also observed. Clustering analysis revealed that the distances of the five species according to the lectin binding profiles are consistent with that of the genome sequence based phylogenetic tree except for rabbit. The procedure that we established in this study could be generally applicable for sperm from other species or defect sperm from the same species. We believe the lectin binding profiles of the mammalian sperm that we established in this study are valuable for both basic research and clinical studies.     

Engineering the Saccharomyces cerevisiae β-Oxidation Pathway to Increase Medium Chain Fatty Acid Production as Potential Biofuel

Fatty acid-derived biofuels and biochemicals can be produced in microbes using β-oxidation pathway engineering. In this study, the β-oxidation pathway of Saccharomyces cerevisiae was engineered to accumulate a higher ratio of medium chain fatty acids (MCFAs) when cells were grown on fatty acid-rich feedstock. For this purpose, the haploid deletion strain Δpox1 was obtained, in which the sole acyl-CoA oxidase encoded by POX1 was deleted. Next, the POX2 gene from Yarrowia lipolytica, which encodes an acyl-CoA oxidase with a preference for long chain acyl-CoAs, was expressed in the Δpox1 strain. The resulting Δpox1 [pox2+] strain exhibited a growth defect because the β-oxidation pathway was blocked in peroxisomes. To unblock the β-oxidation pathway, the gene CROT, which encodes carnitine O-octanoyltransferase, was expressed in the Δpox1 [pox2+] strain to transport the accumulated medium chain acyl-coAs out of the peroxisomes. The obtained Δpox1 [pox2+, crot+] strain grew at a normal rate. The effect of these genetic modifications on fatty acid accumulation and profile was investigated when the strains were grown on oleic acids-containing medium. It was determined that the engineered strains Δpox1 [pox2+] and Δpox1 [pox2+, crot+] had increased fatty acid accumulation and an increased ratio of MCFAs. Compared to the wild-type (WT) strain, the total fatty acid production of the strains Δpox1 [pox2+] and Δpox1 [pox2+, crot+] were increased 29.5% and 15.6%, respectively. The intracellular level of MCFAs in Δpox1 [pox2+] and Δpox1 [pox2+, crot+] increased 2.26- and 1.87-fold compared to the WT strain, respectively. In addition, MCFAs in the culture medium increased 3.29-fold and 3.34-fold compared to the WT strain. These results suggested that fatty acids with an increased MCFAs ratio accumulate in the engineered strains with a modified β-oxidation pathway. Our approach exhibits great potential for transforming low value fatty acid-rich feedstock into high value fatty acid-derived products.     

Design,Synthesis, Molecular Docking,and Biological Evaluation of New Emodin Anthraquinone Derivatives as Potential Antitumor Substances

The emodin anthraquinone derivatives are generally used in traditional Chinese medicine due to their various pharmacological activities. In the present study, a series of emodin anthraquinone derivatives have been designed and synthesized, among which 1,3‐dihydroxy‐6,8‐dimethoxyanthracene‐9,10‐dione is a natural compound that has been synthesized for the very first time, and 1,3‐dimethoxy‐5,8‐dimethylanthracene‐9,10‐dione is a compound that has never been reported earlier. Interestingly, while total seven of these compounds showed neuraminidase inhibitory activity in influenza virus with inhibition rate more than 50 %, specific four compounds exhibited significant inhibition of tumor cell proliferation. The further results demonstrate that 1,3‐dimethoxy‐5,8‐dimethylanthracene‐9,10‐dione showed the best anticancer activity among all the synthesized compounds by inducing highest apoptosis rate to HCT116 cancer cells and arresting their G0/G1 cell cycle phase, through elevation of intracellular level of reactive oxygen species (ROS). Moreover, the binding of 1,3‐dimethoxy‐5,8‐dimethylanthracene‐9,10‐dione with BSA protein has thoroughly been investigated. Altogether, this study suggests the neuraminidase inhibitory activity and antitumor potential of the new emodin anthraquinone derivatives.     

The hybrid bacterial foraging algorithm based on many-objective optimizer

A new multi-objective optimized bacterial foraging algorithm - Hybrid Multi-Objective Optimized Bacterial Foraging Algorithm (HMOBFA) is presented in this article. The proposed algorithm combines the crossover-archives strategy and the life-cycle optimization strategy, look for the best method through research area. The crossover-archive strategy with an external archive and internal archive is assigned to different selection principles to focus on diversity and convergence separately. Additionally, according to the local landscape to satisfy population diversity and variability as well as avoiding redundant local searches, individuals can switch their states periodically throughout the colony lifecycle with the life-cycle optimization strategy. all of which may perform significantly well. The performance of the algorithm was examined with several standard criterion functions and compared with other classical multi-objective majorization methods. The examiner results show that the HMOBFA algorithm can achieve a significant enhancement in performance compare with other method and handles many-objective issues with solid complexity, convergence as well as diversity. The HMOBFA algorithm has been proven to be an excellent alternative to past methods for solving the improvement of many-objective problems.