Isolation and amino acid sequence of a serine proteinase inhibitor from common flax (Linum usitatissimum) seeds

LUTI (Linum usitatissimum trypsin inhibitor), a member of the potato inhibitor I family, has been isolated from seeds of flax by ethanol fractionation, ion exchange chromatography on CM-Sephadex C-25, affinity purification on immobilized methylchymotrypsin (alpha-chymotrypsin in which His57 has been converted to 3-methylhistidine) in the presence of 5M NaCl, and finally by reversed-phase HPLC. The 7655 Da inhibitor consists of a single polypeptide chain of 69 residues with one disulfide bridge. The molecule is acetylated at the N terminus. Its primary structure has been determined after limited proteolysis of the native molecule with trypsin at the reactive site, cleavage with cyanogen bromide or arginyl endopeptidase (Arg-gingipain), and alcoholytic deacetylation of the N-terminally blocked serine. The association constants (K(a)) of LUTI with bovine beta-trypsin and alpha-chymotrypsin are 3.58x10(10) M(-1) and 5.02x10(5) M(-1), respectively. High NaCl concentration (3M) increased the association constant of LUTI with alpha-chymotrypsin to 6.64x10(7) M(-1). To our knowledge, LUTI is the first serine-proteinase-type inhibitor isolated from a plant of the Linaceae family.     

汉语框架网中未登录词元的框架选择

汉语框架网的低覆盖率导致汉语句子中存在许多未登录的词元,严重制约着汉语的框架语义分析任务。针对未登录词元的框架识别问题,该文借助同义词词林的词义信息,提出基于平均语义相似度计算及最大熵模型两种方法,采用静态特征与动态特征相结合的特征选择方法。实验证明,这两种方法都能有效地实现未登录词元的框架选择,基于相似度计算的方法(TOP-4)获得78.61%的准确率;基于最大熵的方法结果可达87.29%,同时在新闻语料上达到了75%的准确率。     

超滤膜等离子体改性分离大豆蛋白的研究

分别用氧气和氩气等离子体对醋酸纤维素超滤膜进行表面改性,用大豆分离蛋白溶液进行超滤实验,结果表明等离子体处理后膜的接触角变小,亲水性能大大增强,超滤过程可以在保持截留率不变的情况下使膜的透水率增大2～3倍,同时膜的抗污染性能增强。研究发现在相同的等离子体反应条件下,氩气的处理效果优于氧气。     

Influence of polymer on cement hydration in SBR-modified cement pastes

The influence of styrene-butadiene rubber (SBR) latex on cement hydrates Ca(OH)₂, ettringite, C₄AH₁₃ and C-S-H gel and the degree of cement hydration is studied by means of several measure methods. The results of DSC and XRD show that the Ca(OH)₂ content in wet-cured SBR-modified cement pastes increases with polymer-cement ratio (P/C) and reaches a maximum when P/C is 5%, 10% and 10% for the pastes hydrated for 3 d, 7 d and 28 d, respectively. With wet cure, appropriate addition of SBR promotes the hydration of cement, while the effect of SBR on the content of Ca(OH)₂ and the degree of cement hydration is not remarkable in mixed-cured SBR-modified cement pastes. XRD results illustrate that SBR accelerates the reaction of calcium aluminate with gypsum, and thus enhances the formation and stability of the ettringite and inhibits the formation of C₄AH₁₃. The structure of aluminum-oxide and silicon-oxide polyhedron is characterized by ²⁷Al and ²⁹Si solid state NMR spectrum method, which shows that tetrahedron and octahedron are the main forms of aluminum-oxide polyhedrons in SBR-modified cement pastes. There are only [SiO₄]⁴⁻ tetrahedron monomer and dimer in the modified pastes hydrated for 3 d, but there appears three-tetrahedron polymer in the modified pastes hydrated for 28 d. The effect of low SBR dosage on the structure of aluminum-oxide and silicon-oxide polyhedron is slight. However, the combination of Al³⁺ with [SiO₄]⁴⁻ is restrained when P/C is above 15%, and the structure of Al³⁺ is changed obviously. Meantime, the polymerization of the [SiO₄]⁴⁻ tetrahedron in C-S-H gel is controlled.     

The kinetics of B‐a and P‐a type copolybenzoxazine via the ring opening process

The structure of benzoxazines is similar to that of phenolic resin through thermal self‐curing of the heterocyclic ring opening reaction that neither requires catalyst nor releases any condensation byproduct. These polybenzoxazine resins have several outstanding properties such as high thermal stability and high glass transition temperature. To better understand the curing kinetics of this copolybenzoxazine thermosetting resin, dynamic and isothermal differential scanning calorimetry measurements were performed. Three models, the Kissinger method, the Flynn–Wall–Osawa method, and the Kamal method, were used to describe the curing process. Dynamic kinetic activation energies based on Kissinger and Flynn–Wall–Osawa methods are 72.11 and 84.06 KJ/mol, respectively. The Kamal method based on an autocatalytic model results in a total order of reaction between 2.66 and 3.03, depending on curing temperature. Its activation energy and Arrhenius preexponential are 50.3 KJ/mol and 7959, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 730–737, 2005     

新建本科院校学报的科学定位与发展研究

新建本科院校学报存在定位不够科学、学术性不强、特色不突出和编辑队伍素质参差不齐等问题.进行科学的定位是新建本科院校学报可持续发展的前提.应根据校情和社会环境条件来对学报进行定位.在科学定位基础上,要坚持以作者为本,提高原创水平;以编辑为本,提高编辑质量;以读者为本,发挥社会效益.同时,要创新学报管理机制、选题策划和征稿机制,塑造学报特色,从而实现新建拳科院校学报的科学发展.     

黑龙江省交通数字化中元数据创建问题研究

交通信息数据内容繁杂且数据量庞大,建立交通数据元数据是对其进行管理及共享的有效、可行的方法。通过对黑龙江省交通信息数据元数据的现状分析,对已有的元数据标准做必要的改进,重新建立黑龙江省交通信息基础元数据集,使黑龙江省交通信息基础元数据管理和应用更加科学、合理、规范。     

贫瘦煤替代瘦煤制备优质焦炭性能研究

根据瘦煤和贫瘦煤结焦机理、成焦显微结构和粒度变化特征,对贫瘦煤替代瘦煤的结焦显微结构、焦炭性能进行了研究。结果表明,瘦煤与贫瘦煤可以互相替代,并且在合理配比的情况下可改善焦炭质量;通过合理的粒度调整和配煤,在提高贫瘦煤或瘦煤比率的同时亦可得到优质焦炭。     

高碱值烷基苯磺酸钙的制备研究

以烷基苯磺酸、氢氧化钙、氧化钙和二氧化碳为原料,甲苯为溶剂,甲醇为促进剂,制备高碱值烷基苯磺酸钙,考查了原料配比、反应时间等对产品投入产出比和总碱值的影响,结果表明,合成工艺的最佳条件为:氧化钙和氢氧化钙与烷基苯磺酸的摩尔比为2.5∶1,氧化钙和氢氧化钙的摩尔比为1∶10,促进剂甲醇的用量为2.2 mol,中和反应时间为0.5 h,水加入量为8.4 mol,二氧化碳导入速率为100 mL/m in,二氧化碳导入量为1 mol。产品投入产出比大于70,总碱值接近400。     

Video super-resolution reconstruction method based on deep Back projection and motion feature fusion

How to effectively utilize inter-frame redundancies is the key to improve the accuracy and speed of video super-resolution reconstruction methods. Previous methods usually process every frame in the whole video in the same way, and do not make full use of redundant information between frames, resulting in low accuracy or long reconstruction time. In this paper, we propose the idea of reconstructing key frames and non-key frames respectively, and give a video super-resolution reconstruction method based on deep back projection and motion feature fusion. Key-frame reconstruction subnet can obtain key frame features and reconstruction results with high accuracy. For non-key frames, key frame features can be reused by fusing them and motion features, so as to obtain accurate non-key frame features and reconstruction results quickly. Experiments on several public datasets show that the proposed method performs better than the state-of-the-art methods, and has good robustness.