Ultra-lightweight cellulose foam material: preparation and properties

Ultra-lightweight cellulose foams were prepared by regeneration of sodium dodecyl sulfate (SDS)/cellulose/NaOH/urea blend solution via mechanical agitation and then freeze-drying. The morphology and properties of the blend solutions and foams were investigated via optical microscope, rheometer, BET and SEM. As a result, it was found that the inclusion complex structure between cellulose macromolecules and the solvent molecules was not destroyed. Moreover, the bubbles were about 20–50 μm in the solutions and larger (>100 μm) in the foams. Not only the micropores (bubbles) but also the nanopores could be observed in the wet and dried foams. The cellulose foams possessed ultra-low density of about 30 mg/cm³ and high specific surface area. The result of X-ray diffraction and Fourier transform infrared spectroscopy indicated that the cellulose foams were transited from cellulose I to cellulose II after dissolution and gelation. Bubbles inside the wet foams weakened the mechanical properties, but inversely increased the mechanical properties in the dried foams. Typical “J”-shaped curves were observed during the mechanical test, which revealed good compressive strength of dried foams. In this work, cellulose foams with ultra-lightweight and good mechanical properties were obtained, which exhibited great potentials for further development and comprehensive utilization of cellulose.     

基于DSP的变电站自动化系统测量模块研究

选用SA9904B为电量测量芯片、DSP 2407为系统微处理器,设计了变电站测量模块,该模块响应速度快、可靠性强,除了具有测量功能外,还具有一定的控制功能,比传统的测量模块更具优越性。     

基础教育数学物理化学教材用字用词调查（二）

为了更好地了解语言学习、语言能力培养与学科知识获取之间的关系，语言学习、语言能力培养与学科知识获取之间的关系，论文统计了基础教育阶段的数学、物理、化学三科教材中汉字、词语的使用情况，分析了它们的字词的种数、使用频率数、与语文科教材的用字用词的共见与独见情况。发现它们的字种数、词种数及总词次较少，复现率较低主要由以下四类构成：1．学科术语；2．一般性的语文字词；3．指称日常生活中一些特定的物、人、事的字词；4．教学类字词。     

Buckling Analysis of Soft Nanostructure in Nanoimprinting

Nanoimprint lithography is an economical and convenient method for manufacturing nanostructures, which has developed very quickly and has been widely used in the nanoindustry. However, during the process of nanoimprinting, mechanical instabilities of soft nanostructures could lead to buckling. In order to study the mechanism of this problem, we analyze the buckling of one vertical elastic column under its own weight. Based on the comparison between two critical heights of different substrates （rigid and elastic）, we conclude that the approximation of considering the substrate as rigid is acceptable. Furthermore the interaction between columns with the deformation of a substrate could lead to collective buckling. Our theoretical
calculations show that whether the columns are elastic or rigid makes little difference for the buckling modes.     

Fermion Tunnels of Cylindrical Symmetric Black Hole and?the?Corrected Entropy

Using the method proposed by Banerjee and Majhi, we researched fermion tunneling from cylindrical symmetric black hole, and obtained the correctional entropy. In our work, we first prove that the ratios of the wave function’s components are constants near the horizon, so the reasonable action form of the Dirac equation can then be gotten. From the method beyond semiclassical approximation, we finally calculate the Hawking temperature and correctional entropy.     

农业院校学生农村就业的利与弊

在当今社会竞争如此激烈的大环境下,高校毕业生的规模又如此的庞大,就业的压力越来越大,有一种呼声:农业院校的毕业生到农村就业是唯一途径,这种声音普遍受到社会和人们的关注。其实现在的农业院校并非以前仅仅是农业专业,因经济全球化的快速发展让农业院校在专业方向的建设上也开始多元化。再且,由于现在的毕业生都是80后、90后,去农村就业有利有弊,所以农村并不是农业院校毕业生的唯一出路。     

关于西南边疆地方高校对外汉语专业师资培养的思考

根据中国西南与东盟国家文化的相异处以及东盟国家对汉语教学的具体需求、中国文学文化的教学规律,整理出有针对性的中国文学、文化教学内容,将文学与文化这两门课程对应联系起来,教学过程应着眼于学生的参与、师范技能以及文化素养的提高,通过注重习得、优化文学文化课程教学的内容和方法来提高学生的师范技能与文化素养,培养学生对中国文学、文化抱有一种积极的情感,是提高西南边疆地方高校对外汉语专业师资培养质量的有效途径。     

广义加权极大Morrey空间中次线性算子的有界性质

该文给出定义在R~n上的一类广义加权极大Morrey空间.证明一类次线性算子,包括分数次积分算子,在该类空间中的有界性质.同时还研究该类次线性算子的交换子在广义加权极大Morrey空间中的有界性质.