钢筋混凝土圆管长涵的挖基放样法

高等级公路的钢筋混凝土圆管涵一般比较长，要满足施工规范的要求，施工放样是比较困难的。提出先依据设计涵长进行分段计算，然后再按计算结果进行施工放样。这样才减少施工放样的麻烦。

基体能量释放率对开孔层压板承载能力的影响研究

文章针对复合渐进损伤分析中能量释放率对计算结果的影响进行系统的研究。数值试验结果显示,基体的能量释放率对复合材料结构的初始破坏载荷有较大影响;对结构最终破坏载荷影响不显著。根据数值试验结果对基体能量释放率影响机理进行阐述。研究结果可为复合材料计算分析提供理论指导,为参数设置提供依据。

海洋勘察船基盘收放系统研制及应用

基盘收放系统是勘察船钻探系统的关键部件,主要用于钻柱定位、基盘收放及井口取样监控等工作。为解决基盘恒张力收放、井口定位和监测控制等问题,开展了基盘绞车、补偿装置、勘察基盘和脐带缆绞车的结构分析,对补偿装置和勘察基盘进行了理论计算与技术方案分析,基于此设计了配套于“海洋地质十号”勘察船的基盘收放系统。对该系统进行了厂内试验和现场应用,应用结果表明:基盘绞车和脐带缆绞车提升及下放功能、补偿装置恒张力补偿功能、脐带缆绞车恒张力功能、勘察基盘监测及控制功能均满足设计要求,取得了预期的使用效果。该基盘收放系统的研制及应用推进了海洋勘察关键装备的国产化进程,也为后续3000 m水深基盘收放系统的研制和地质调研提供了一定的参考。

基于AUV垂直面运动控制的状态增减多模型切换

自主水下机器人(autonomous underwater vehicle,AUV)系统垂直面运动具有强耦合性、非线性等特点导致AUV系统垂直面难以精确控制,且其纵倾角需控制在某一阈值内,以保证系统安全。根据以上控制要求与AUV垂直面运动模型特点,提出将其解耦为深度控制子模型与纵倾角控制子模型,构建AUV系统垂直面运动控制模型集,根据模型集所含两子模型特点,提出了状态变量增减的多模型切换的概念。基于切换系统稳定判据——共同Lyapunov函数法,提出了变加权多模型切换策略,实现了切换过程的稳定性,避免了切换过程的抖动问题。多次湖泊试验证明,加权多模型切换策略避免了由于期望深度变化而造成的执行机构饱和、深度和纵倾角超调量过大等问题,且改善了AUV系统深度运动的静动态控制品质。

可食性膜在食品保鲜中的应用现状及研究进展

在食品保鲜领域,可食用天然抗菌保鲜膜是一种重要的可生物降解膜,具有易降解、成本低、来源广等特点。介绍了多糖膜、蛋白膜和脂质膜3种可食性涂膜在食品保鲜中的应用现状,综述了复合成膜技术、纳米颗粒制备技术及添加植物精油在制备可食性涂膜中的研究进展,以期为可食性包装材料在保鲜领域中的进一步研究提供参考借鉴。

Cavity Ringdown Spectroscopy of PH2 Radical in 465-555 nm

Absorption spectra of jet-cooled PH2 radicals were recorded in the wavelength range of 465- 555 nm using cavity ringdown spectroscopy. The PH2 radicals were produced in a supersonic jet by pulsed direct current discharge of a mixture of PHa and SF6 in argon. Seven vibronic bands with fine rotational structures have been observed and assigned as 0 0^, 2 0^n, and 2 1^n （n=1- 3） bands of the A^2A1- X~ 2B1 electronic transition. Rotational assignments and rotational term values for each band were re-identified, and the molecular parameters including rotational constants, centrifugal distortion constants, and spin-rotation interaction constants were also improved with reasonably high precision. In addition, large perturbations observed in each quantum number of total angular momentum of the a axis level of the excited vibronic states were briefly discussed.

Microstructure characteristics and mechanical properties of TiB/Ti-1.5Fe-2.25Mo composites synthesized in situ using SPS process

TiB/Ti-1.5Fe-2.25Mo composites were synthesized in situ using the spark plasma sintering （SPS） method at temperatures of 850-1150 °C. The effect of the sintering temperature on microstructure and mechanical properties of the composites was investigated. The results indicate that the aspect ratio of the in situ synthesized TiB whiskers in Ti alloy matrix decreases rapidly with an increase in sintering temperature. However, both the relative density of the sintered specimens and the volume content of TiB whiskers in composites increase with increasing sintering temperature. Thus, the bending strength of the composites synthesized using SPS process increases slowly with increasing the sintering temperature from 850 to 1150 °C. TiB/Ti-1.5Fe-2.25Mo composite synthesized at 1150 °C using SPS method exhibits the highest bending strength of 1596 MPa due to the formation of fine TiB whiskers in Ti alloy matrix and the dense microstructure of the composite.

Microstructure and mechanical properties of TiAl-based alloy prepared by double mechanical milling and spark plasma sintering

A fine-grained TiAl alloy with a composition of Ti-45Al-2Cr-2Nb-1B-0.5Ta-0.225Y （mole fraction, %） was prepared by double mechanical milling（DMM） and spark plasma sintering（SPS）. The relationship among sintering temperature, microstructure and mechanical properties was studied. The results show that the morphology of double mechanical milled powder is regular with size in the range of 20-40 μm and mainly composed of TiAl and Ti3Al phases. The main phase TiAl and few phases Ti3Al, Ti2Al and TiB2 were observed in the SPSed alloys. For samples sintered at 900 ℃ the equiaxed crystal grain microstructure is achieved with size in the range of 100-200 nm. With increasing the SPS temperature from 900 ℃to 1000 ℃ the size of equiaxed crystal grain obviously increases, the microhardness decreases from HV658 to HV616, and the bending strength decreases from 781 MPa to 652 MPa. In the meantime, the compression fracture strength also decreases from 2769 MPa to 2669 MPa, and the strain to fracture in compression increases from 11.69% to 17.76%. On the base of analysis of fractographies, it shows that the compression fracture transform of the SPSed alloys is intergranular rupture.

Chromosomal Localization of Genes bz1,bz2 in Maize by Using Ultra-sensitive FISH with Tyramide Signal Amplification(TSA-FISH)

It has been reported that endosperm undergoes programmed cell death (PCD) during maize kernel development.Both bz1 (bronze ) and bz2 are anthocyanin biosynthetic genes,and related to development of aleuronic layer of maize seeds.Tyramide signal amplification fluorescence in situ hybridization (TSA FISH) is a novel and high sensitive FISH technique,which is suitable for routine application in plant cytogenetic research.Using this technique,we physically mapped the bz1 gene onto the short arm of chromosome 9 and the long arm of chromosome 1;the percentage distances from centromere to hybridization site were 40.2,75.4 respectively,and the bz2 onto the long arm of chromosome 1 and the short arm of chromosome 5;the percentage distances from centromere to hybridization site were 21.6,15.3 separately.The TSA FISH techniques of small low copy DNA sequences for plants are discussed.

Effects of Ti-based additives on Mg_2FeH_6 dehydrogenation properties

Mg2FeH6 doped with and without Ti and its alloys (TiMn2, TiAl) were prepared combing ball milling and heat treatment. The effects of these additives on the dehydrogenation performance of Mg2FeH6 were studied systematically. The results show that all additives have favor influence on improving the hydrogen desorption property of Mg2FeH6. Especially, TiMn2 exhibits prominent effect on enhancing the dehydrogenation kinetics of Mg2FeH6. Moreover, the activation energy of TiMn2-doped Mg2FeH6 calculated by Kissinger equation is 94.87 kJ/mol, which is 28 kJ/mol lower than that of the undoped Mg2FeH6. The cycling tests suggest that the improved dehydrogenation kinetics of Mg2FeH6 doped by TiMn2 can maintain in the second cycle.

Survey of Radiosensitizing Agents (Synthesized Chemicals and Gene Therapeutic Agents) Since 2000

Radiotherapy has played an important role in treatment of tumor patientssince it appeared about 80 years ago, and has been an indispensable part of the management of about50% of tumors (especially 60% - 70% of malignant tumors). Currently, radiotherapy is used in simpleand palliative therapy, adjuvant therapy after or before surgery, simultaneous radio-chemotherapy,combined BRM (biological response modifier) therapy, ets. Radiosensitizing agents enhance theradiation effects on tumor cells so as to have better responses in radiotherapy. Tumor intrinsicradiosensitivity is affected by the hy-poxic level in solid tumor, the ability of the cells torepair the radiation-induced DNA damage, the number of cells which have a clonogenic capability toreestablish uncontrolled cell growth, the amount of dividing cells, and the distribution of cellsthroughout the cell cycle. Consequently , it is necessary and useful to add one or moreradiosensitizing agents in radiotherapy to increase the radio-sensitivity of tumor cells.

A Preliminary Study of Rotundine-Polyion Complex Release System

A rotundine-polyion complex(PIC)release system was prepared first by granulation of rotundine containing chitosan acetate solution and then by complexing with carboxymethyl glucomannan(CMGM)solution on the granular surface.The granules have an average diameter of 1.38-1.53 mm and the drug content reaches 62.89％.The external release tests showed T_(50) to be 45 rain and the total release time 4 h in an artificial gastric juice,while no more than 60％ of the drug was released in the same period of time in an ar- tificial intestinal fluid.The various factors affecting the external release were examined.

Molecular Identification of Gallibacterium from Hen and Analysis of Its 16S rRNA Gene

Two strains of Gallibacterium, isolated from one laying hen flock in Zhengzhou City of Henan Province, were identified by the morphological observation, genus -specific PCR, and analysis of 16S rRNA gene, which was used to generate the phylogenetic tree, with the 21 members of the 12 genera belonging to Pasteurellaceae to analyze the homology. Two strains were named Yu-ZZ-HL-I-SLG and Yu-ZZ-HL-II-GZ. The comparative result of the 16S rDNA sequence shows that the 2 isolated strains are identical in sequence; the highest identity （99.9%） was observed between the isolated strain and one of the strains of Gallibacterium anatis （AF22.8002）, the homologies between the isolated strain and 3 strains of gallibacterium accessed in NCBI （AF22.8016, Gallibacterium genomosp. 1, AF228017, Gallibacterium genomosp. 2, AF22.8018, Gal- libacterium genomosp. 1 ） were above 97.1%, higher than that of the isolated strain and the other strains of the other 11 genera which were between 90.7% -93.2%. It can be seen from the phylogenetic tree that the 2 isolated strains and the other 4 strain of gallibacterium fell into the same branch, furthermore the 2 isolated strains and the strain of Gallibacterium anatis locate in an internal branch, indicating that the 2 isolated strains belong to Gallibacterium anatis.

Size-controlled preparation of hollow silica spheres and glyphosate release

Different-sized hollow SiO2 spheres of 249–1348 nm in diameter were successfully prepared by using Na2SiO3 as the precursor and using polystyrene and polystyrene-methyl acrylic acid latexes as the templates. The diameter and shell thickness of the hollow SiO2 spheres increase with increasing the latex template diameter at a given mass ratio of SiO2 to latex template. The diameter and shell thickness of the hollow SiO2 spheres also increase with increasing the mass ratios of SiO2 to latex template. The presence of carboxylic acid groups on the surfaces of polystyrene-methyl acrylic acid latex templates favors the formation of dense and uniform SiO2 shells. The hollow SiO2 sphere is constructed by mesoporous shell with large specific surface area. When glyphosate is used as a release model chemical, glyphosate release rate is tuned by varying the shell thickness.

Changes of Amino Acid Content in Leaves of Agropyron cristatum Under Grazing Pressure

By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazing pressure. How- ever, the contents of free glycine （Gly） and proline （Pro） were very sensitive to grazing. Glycine content in grazing population was higher than that in non-grazing population at flowering stage; the content of free proline in non-grazing population was higher than that in grazing population at tillering, heading and especially flower- ing stage; the content of free proline under grazing pressure at maturity stage was higher than that of non-grazing population.

Liposome transfected to plasmid-encoding endostatin gene combined with radiotherapy inhibits liver cancer growth in nude mice

AIM： To evaluate whether intratumoral injection of liposome-endostatin complexes could enhance the antitumor efficacy of radiation theapy in human liver cardnoma （BEL7402） model.METHODS： Recombinant plasmid pcDNA3.End was transfected into human liver carcinoma cell line （BEL7402） with lipofectamine to produce conditioned medium. Then BEL7402 cells and human umbilical vein endothelial cells （HUVECs） were treated with the conditioned medium. Cell cycle and apoptosis were analyzed by flow cytometer and endothelial cell proliferation rates were determined by MTT assay. The antitumor efficacy of endostatin gene combined with ionizing radiation in mouse xenograft liver tumor was observed.RESULTS： Endostatin significantly suppressed the S phase fraction and increased the apoptotic index in HUVECs. In contrast, endostatin treatment had no effect on BEL7402 cell apoptosis （2.1±0.3% vs 8.9±1.3%, t= 8.83, P= 0.009〈0.01） or cell cycle distribution （17.2±2.3% vs 9.8±1.2%, t = 4.94,P = 0.016〈0.05）. The MTT assay showed that endostatin significantly inhibited the proliferation of HUVECs by 46.4%. The combination of local endostatin gene therapy with radiation therapy significantly inhibited the growth of human liver carcinoma BEL7402 xenografts, the inhibition rate of tumor size was 69.8% on d 28 compared to the untreated group. The tumor volume in the pcDNA3.End combined with radiation therapy group （249±83 mm^3） was significantly different from that in the untreated group （823±148 mm^3, t= 5.86, P= 0.009〈0.01） or in the pcDNA3 group （717±94 mm^3, t= 6.46, P= 0.003〈0.01）. Endostatin or the radiation alone also inhibited the growth of liver tumor in vivo, but their inhibition effects were weaker than those of endostatin combined with radiation, the inhibition rates on d 28 were 44.7% and 40.1%, respectively.CONCLUSION： Endostatin not only significantly suppresses tumor growth but also enhances the antitumor efficacy of radiation therapy in human carcinoma xenograft.

Cloning and Expression of Gonadotrophin Releasing Hormone Receptor in Apis cerana cerana

[Objective] This study was to clone the GnRH （gonadotropin-releasing hormone）, and to investigate its expression in Apis cerana cerana. [Method] The cDNA sequence of GnRHR gene was amplified from Apis cerana cerana by using RT-PCR techniques. It was conducted with bioinformatics analysis and the in situ hybridization histochemistry of its expression products was studied. [Result] The sequence analy- sis showed that the full cDNA sequence was 1 050 bp with the open reading frame of 1 050 bp, and it encoded 349 amino acid residues. The deduced amino sequence included 7 transmembrane regions, and the predicted molecular mass and isoelectric point were 40.6 kD and 9.54, respectively. The cluster analysis showed that the GnRHR from ＇,4. cerana cerana had close relationship to the GnRHR II from other insects. In situ hybridization showed that Bee-GnRHR staining was specifically localized to the brain, intestine, fat body and testis. [Conclusion] The results indicated that the GnRHR provided molecular bond for the reproduction and metabolism for insects, and suggested a functional role for bee-GnRHR signaling in the coupling of reproduction activities and environment conditions.

In vitro Evaluation of Lysozyme-loaded Microspheres in Thermosensitive Methylcellulose-based Hydrogel

Long-terrn injectable microspheres have some inherent disadvantages such as migration of microspheres from the originalsite an.d the burst effect. In order to avoid these problems, microsphere-loaded thermosensitive, hydrogel system was designed and expected to achieve a zero-order release Of biomolecular drugs in relativehigh initial drug loadings. Lysozyme, an antibacterial protein usually used to reduce prosthetic valve endocarditis,was selected as the model drug. Poly （DL-lactide-co-glycolide） （PLGA） microspheres, prepared by solvent evaporation method, were employee to encapsulate lysozyme and dispersed into thermosensitive pre-gel solution containing methylcellulose （MC）, polyethylene glycol （PEG）, sodium citrate （SC）, and sodium alginate （SA）. The mixture could act asadrug reservoir by.performing sol-gel transition rapidly if the temperature was raised from roomtemperature to 37℃. The in vitro release results showed that the burst effect was avoided due to strengthening ofdiffusion resistance in the gel. The formulation was able.to deliver lysozy.me for over.30 daysin a nearly zero-order release profile with a rate of 32.8μg.d^-1 which exhibits its remarkable potential for effective aoolication in long-term drug delivery.

Release of Hydroxyl Ions Associated with Chloride Adsorption in Electrodialyzed Variable Charge Soils

The release of hydroxyl ions from two variable charge soils associated with the adsorption of chloride in NaClO4 solutions was examined. The complete release required about 10 minutes. The release decreased with the increase in the NaClO4 concentration at first and eventually was little affected by the latter. The adsorption of Cl- was almost linearly related with the quantity of NaCl added to the system, while the OHrelease-NaCl curve varied with the soil type and the concentration of NaClO4. The logarithm of the quantity of released OH- was linearly related with the pH. The ratio of released OH- to adsorbed Cl- was larger in dilute NaClO4 solutions than in concentrated solutions and decreased with increasing NaCl.