一种超体积准则多目标遗传算法的螺旋桨叶片优化方法

为改善螺旋桨叶片敞水效率,用结合超体积准则的多目标遗传算法优化螺旋桨桨型设计.优化过程中,桨叶形状用B样条曲线拟合,利用面元法建立桨型性能模型.将计算螺旋桨升力和阻力转化为降低阻升比、桨型面积差和压力方差三个优化目标,得到优化后的螺旋桨剖面形状,并将优化前后的螺旋桨进行流体分析.结果表明,超体积准则结合多目标遗传算法进行螺旋桨叶片优化是有效的.优化后的桨型在面积差变化较小的情况下三个目标均有明显改进,螺旋桨水动力性能达到预期目标,敞水效率提升12%.     

Immobilization of carboxyl-modified multiwalled carbon nanotubes in chitosan-based composite membranes for U(VI) sorption

Journal of Radioanalytical and Nuclear Chemistry - The carboxyl-modified multiwalled carbon nanotubes were immobilized in chitosan-based composite membranes (CS-CNTs) which were used as efficient...     

Color tuning of up-conversion emission in ytterbium,erbium, aluminum tri-doped zinc oxide crystal by adjusting aluminum concentration

Ytterbium, erbium, aluminum tri-doped zinc oxide crystal was synthesized, which can turn color from red to green up-conversion luminescence through adjusting aluminum content. When the aluminum concentration reached 4?mol%, the color of up-conversion emission first turn from red to green. Meanwhile, the ratio of red to green emission reduced from 25.32 to 0.26, and the coordinates of chromaticity coordinate calculation changes from (0.5749, 0.3378) to (0.2190, 0.7169) with aluminum concentration range from 0 to 4?mol%. The up-conversion emission peaks at 521, 542, and 660?nm of sample originate from the transitions of ²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2, and ⁴F_9/2 → ⁴I_15/2 of erbium ions, respectively. X-ray diffraction patterns perform the better crystallization degree with increasing aluminum concentration. The scanning electron microscopy images show the porous and lamellar structures with different aluminum concentrations. A convenient but effective design to obtain ytterbium, erbium, aluminum tri-doped zinc oxide up-conversion luminescence is reported, which can turn color from red to green.     

Pollution characteristics and risk assessment of uranium and heavy metals of agricultural soil around the uranium tailing reservoir in Southern China

For the first time the pollution of the paddy soil within 2 km around the uranium tailing reservoir was investigated. The concentrations of U, Cd, Cr, Pb, Cu, Zn, Hg and As were determined by ICP-MS. The study showed that there was severe pollution in the first area (within 0–1 km of the tailing reservoir), which was caused by Cd, As, U and Hg. The pollution level of the second area (within 1–2 km) was relatively low. Hg and As were the main pollutants. In the first area, the contamination degree and risk of elements were positively correlated with the distance from the tailing reservoir. The second area was less polluted and influenced by mining and human activities because of mountain barriers.     

Synthesis of Cholesterylated Thiogalactosides for Gene Delivery

A series of cholesterylated thiogalactosides L₁ –L₆ the cell targeting ligands for gene delivery to hepatocytes, was synthesized. Related poly(ethylene glycol) chain was used as a bridge for the attachment of galactoside on one hydroxyl end, while the other hydroxyl end was linked with cholesterol. This design provided an effective entry for the synthesis of a poly(ethylene glycol) compound with the hepatocyte targeting.     

Sarcaglarols A—D,Lindenane−Monoterpene Heterodimers from Sarcandra glabra Based on Molecular Networks

Sarcaglarols A—D ( 1 — 4 ), two pairs of lindenane?monoterpene heterodimers fused by a 1,2‐dioxane moiety, were discovered and isolated from the leaves of Sarcandra glabra guided by MS/MS molecular networking‐based strategy. Their planar structures, absolute configurations of basic skeleton and flexible polyhydric side chain were established by analysis of HRESIMS, NMR spectroscopic data, ECD spectrum, and the X‐ray diffraction study of isopropylidene derivatives. An intermolecular [2+2+2] cycloaddition may play a key role in the biosynthesis pathway of the 1,2‐dioxane moiety fused lindenane?monoterpene heterodimer skeleton, which can be recognized as the biogenetic precursors of our previous reported lindenane?normonoterpene conjugates. In addition, compounds 1 , 3 and 4 exhibited moderate inhibitory effects of lipid accumulation in free fatty acid‐exposed L02 cells.     

Theoretical Design of Multi‐Nitroxyl Organocatalysts with Enhanced Reactivity for Aerobic Oxidation

Higher catalytic performances of N,N′,N′′‐trihydroxyisocyanuric acid (THICA), N,N‐dihydroxypyromellitimide (NDHPI), and N‐hydroxynaphthalimide (NHNI) than that of N‐hydroxyphthalimide (NHPI) have been demonstrated recently in aerobic oxidation. Herein, the rational design of reactive multi‐nitroxyl organocatalysts has been addressed theoretically by using systematic analysis of some important properties and catalytic activities of yet‐to‐be‐synthesized catalysts. Our results show that 1) NHNI and its analogue, similar to THICA, unlike NHPI and others, are unsuitable for solvent‐ or mediator‐free catalysis due to their strong intramolecular hydrogen‐bonding interactions; 2) increasing the reactive hydroxyimide groups on the same aromatic ring, or doped N atoms or ionic‐pair groups onto the aromatic ring, can improve catalytic reactivity, whereas appropriate enlargement of conjugated aromatic systems results in unchanged activity; 3) the newly designed catalysts are more active than NHPI and NHNI and have catalytic activities comparable to NDHPI and THICA; 4) the ionic‐pair supported case is suggested to be a very active catalyst, even towards inert propane, and can be used as a novel model catalyst for further improvements. The present work will be helpful in designing reactive hydroxyimide organocatalysts.     

恶意书写笔迹的实验研究

恶意书写是一种新型伪装笔迹的手法。它是当事人双方在形成文件(多数是当面书写)时,一方就对笔迹进行了某种程度的伪装,目的是在日后必要的时候通过否认该笔迹是自己所写,非法占有他人财物或逃避责任。实验研究结果表明:是否懂文检知识对恶意书写的具体手段、伪装程度、伪装手段的多样性等方面的影响很大;各类人群中恶意书写的主要伪装手法是加快书写、改变字形、改变字的结构、降低书写水平、改变写法等;不同文化程度和不同年龄的人恶意书写时在伪装手法的多样性、伪装手段及其出现率以及伪装程度上不同,并有一定规律可循。