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151.
樟树籽油的浓硫酸连续催化酯化酯交换 总被引:3,自引:0,他引:3
樟树籽含油量达40%以上,属制备生物柴油的理想原料,至今尚未得到开发利用。本文采用气相色谱法分析测定了樟树籽油的脂肪酸组成及其酯化酯交换反应产物中脂肪酸甲酯组成;采用单因素实验和正交实验法,研究了浓硫酸连续催化樟树籽油酯化酯交换的影响因素并对其反应条件进行了优化 相似文献
152.
N. Azcan S. Saricoban B. Demirci Z. Aytac K. H. C. Baser 《Chemistry of Natural Compounds》2001,37(3):253-255
Oil yields and compositions from seeds of 15Ebenustaxa growing in Turkey were investigated. The yields were found between 4.0% and 13.0%. The seeds ofE. Barbigerashowed the highest whileE. Plumosavar.plumosashowed the lowest yield of oil among the 15 taxa investigated. GC/MS showed that linoleic acid (42.8-55.6%), palmitic acid (13.8-23.6%), and oleic acid (15.9-23.6%) are the main fatty acid components of all the species 相似文献
153.
154.
155.
原子吸收法测定椒目中不同化学形态的锌含量 总被引:1,自引:1,他引:0
结合椒目的市场前景与药效,采用原子吸收分光光度法,分析了不同产地椒目中的锌含量及其形态。使用0.45 μm滤膜、CHCL3将椒目水煎液中的锌分为悬浮态和可溶态、有机态和无机态,建立了锌的四种形态分离分析方法;探讨了正辛醇-水分配体系模拟水煎液中锌在人体胃肠中的分配情况;并采用原子吸收分光光度法测定了椒目中的锌在不同溶剂中的化学形态和溶出特性。结果表明,椒目中的锌以水可煎出态为主,不同产地椒目锌含量不同,但水可煎出态总锌百分率、有机态总锌百分率基本接近。该方法回收率在97.5%~104.0%范围内,相对标准偏差均小于2.36%。应用于实际,结果表明其灵敏度高,重现性好。 相似文献
156.
Seed bubbles are generated on microheaters located at the microchannel upstream and driven by a pulse voltage signal, to improve flow and heat transfer performance in microchannels. The present study investigates how seed bubbles stabilize flow and heat transfer in micro-boiling systems. For the forced convection flow, when heat flux at the wall surface is continuously increased, flow instability is self-sustained in microchannels with large oscillation amplitudes and long periods. Introduction of seed bubbles in time sequence improves flow and heat transfer performance significantly. Low frequency (∼10 Hz) seed bubbles not only decrease oscillation amplitudes of pressure drops, fluid inlet and outlet temperatures and heating surface temperatures, but also shorten oscillation cycle periods. High frequency (∼100 Hz or high) seed bubbles completely suppress the flow instability and the heat transfer system displays stable parameters of pressure drops, fluid inlet and outlet temperatures and heating surface temperatures. Flow visualizations show that a quasi-stable boundary interface from spheric bubble to elongated bubble is maintained in a very narrow distance range at any time. The seed bubble technique almost does not increase the pressure drop across microsystems, which is thoroughly different from those reported in the literature. The higher the seed bubble frequency, the more decreased heating surface temperatures are. A saturation seed bubble frequency of 1000–2000 Hz can be reached, at which heat transfer enhancement attains the maximum degree, inferring a complete thermal equilibrium of vapor and liquid phases in microchannels. Benefits of the seed bubble technique are the stabilization of flow and heat transfer, decreasing heating surface temperatures and improving temperature uniformity of the heating surface. 相似文献
157.
The high prevalence of cancer has been increased the rate of studying about the new formulation of chemotherapeutic drugs. In this regards, one of the suitable options is the use of metal nanoparticles for formulating these drugs. In the recent study, Lens culinaris seed aqueous extract conjugated gold nanoparticles (AuNPs) are reported for the first time to exert a dietary therapeutic potential compared to mitoxantrone in an animal model of acute myeloid leukemia. The synthesized AuNPs were characterized using different techniques including UV–Vis., FT-IR, XRD, FE-SEM, and TEM. DPPH free radical scavenging test was done to evaluate the antioxidant potentials of HAuCl4, L. culinaris, AuNPs, and mitoxantrone. For the analyzing of cytotoxicity effects of HAuCl4, L. culinaris, AuNPs, and mitoxantrone, MTT assay was used on HUVEC, 32D-FLT3-ITD, Human HL-60/vcr, and Murine C1498 cell lines. In vivo assay, induction of acute myeloid leukemia was done by 7,12-Dimethylbenz[a]anthracene (DMBA) in 75 mice. Then, the animals were randomly divided into six subgroups, including control, untreated, HAuCl4, L. culinaris, AuNPs, and mitoxantrone. SEM and TEM images showed uniform spherical morphology and average diameters of 10–40 nm for the nanoparticles. DPPH test revealed similar antioxidant potentials for mitoxantrone and AuNPs. Similar to mitoxantrone, AuNPs had low cell viability dose-dependently against 32D-FLT3-ITD, Human HL-60/vcr, and Murine C1498 cell lines without any cytotoxicity on HUVEC cell line. AuNPs and mitoxantrone significantly (p ≤ 0.05) reduced the weight and volume of liver and spleen, the pro-inflammatory cytokines, and the total WBC, blast, neutrophil, monocyte, eosinophil, and basophil counts and increased the mRNA expression of Sphingosine-1-phosphate receptor-1 and Sphingosine-1-phosphate receptor-5, the anti-inflammatory cytokines, and the lymphocyte, platelet, and RBC parameters as compared to the untreated mice. It looks that AuNPs can be administrated as a chemotherapeutic supplement or drug for the treatment of acute myeloid leukemia in the clinical trial. 相似文献
158.
We present a numerical study of the properties of picosecond supercontinuum (SC) generation when pumping in the normal dispersion region of photonic crystal fibers. Simulation results demonstrate that rogue wave generation can be reduced by adding a weak signal continuous-wave (CW) seed on the main pump pulse. Besides, the red-shifted part of SC exhibits higher degree of coherence and pulse-to-pulse intensity stability. 相似文献
159.
Changlin Ding Meiling Huang Genxiang Zhong Lijun Liu Xinming Huang 《Crystal Research and Technology》2014,49(6):405-413
For the seed‐assisted casting process for silicon ingots, different partition blocks were designed in the directional solidification (DS) furnaces to preserve the seed crystals and optimize the thermal field in the hot‐zone. A transient global model was established to investigate the effects of different partition blocks during the solidification process. The simulation results showed that the partition blocks can significantly influence the temperature distributions and the melt flow fields. From the designed partition blocks, the movable partition block was more favorable for the seed‐assisted DS process. A suitable temperature gradient and a flat seed‐melt (s‐m) interface were obtained, which facilitated the preservation of seed crystals effectively, and an optimized crystal‐melt (c‐m) interface was achieved as well. One of the designs of the movable partition blocks was implemented in quasi‐mono crystalline silicon casting experiments and it has been confirmed that the designed movable partition block was helpful for the improvement of the single crystal area. 相似文献
160.
Abdou M. Abdel‐Rehim Ronald B. Morgan Walter Wilcox 《Numerical Linear Algebra with Applications》2014,21(3):453-471
We consider symmetric positive definite systems of linear equations with multiple right‐hand sides. The seed conjugate gradient (CG) method solves one right‐hand side with the CG method and simultaneously projects over the Krylov subspace thus developed for the other right‐hand sides. Then the next system is solved and used to seed the remaining ones. Rounding error in the CG method limits how much the seeding can improve convergence. We propose three changes to the seed CG method: only the first right‐hand side is used for seeding, this system is solved past convergence, and the roundoff error is controlled with some reorthogonalization. We will show that results are actually better with only one seeding, even in the case of related right‐hand sides. Controlling rounding error gives the potential for rapid convergence for the second and subsequent right‐hand sides. Polynomial preconditioning can help reduce storage needed for reorthogonalization. The new seed methods are applied to examples including matrices from quantum chromodynamics. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献