葡聚糖为载体的双亲型LDL吸附剂吸附动力学研究

合成了以葡聚为载体，同时具有亲水性磺酸基和疏水性胆固醇两类配基的新型低密度脂蛋白（LDL）吸附剂。通过对LDL纯溶液中吸附等温线的测试，比较了以Dextran G-75为载体的双亲型LDL吸附剂与单一亲水型磺酸基配基，单一疏水型胆固醇基吸附剂吸附量和亲和吸附系数的关系。对双亲型LDL吸附剂的吸附动力学进行了初步研究，在LDL溶液中，亲水型磺酸基，疏水型胆固醇配基，双亲型LDL吸附剂对LDL的吸附曲线基本上符合Langmuir吸附方程，另外通过高离子强度NaCl洗脱实验，测定了双亲型LDL吸附剂上具有的磺酸基与胆固醇两类基在对低密脂蛋白吸附过程中所起的配合效果，为下一步作用力机制研究提供了参考依据。     

2-羟丙基三甲基氯化铵壳聚糖的制备及其性能研究

以脱乙酰度为95.37%的壳聚糖(CTS)为原料,异丙醇为溶剂,2,3-环氧丙基三甲基氯化铵为改性剂,于80℃反应12 h合成了水溶性季铵盐2-羟丙基三甲基氯化铵壳聚糖(HACC)。HACC的吸水保水性是CTS的2倍～3倍,加入化妆品中培养2周后菌落总数少于100 CFU.g-1。     

舰船噪声识别(Ⅰ)──总体框架、线谱分析和提取

本系列文章的工作是在舰船噪声谱图的基础上，利用模糊神经网络对舰船进行分类识别。文章Ⅰ叙述了舰船噪声的谱特征由可分离的平稳谱和非平稳谱组成，介绍了既利用有效识别特征（有类别共性和异性的特征）又对特定舰船特征作专门记忆的工作路线及识别框架，对特定舰船的记忆具体体现在特定舰船特征模库一包含有线谱模板库、双重频率谱模板库和平均功率谱模板库。文章Ⅰ又具体讨论了特征提取和建立线谱模板时所碰到的理论、模型、分析参数及线谱提取方法，舰船噪声实际情况和理论之间的差异等问题。文章最后介绍了用机器自动提取线谱的一种方法。系列文章Ⅱ将讨论线谱稳定性、唯一性和线谱模板图；文章Ⅲ将讨论双重谱和平均功率谱的特征提取和模板建立；文章Ⅳ将讨论模糊神经网络和识别。     

舰船噪声识别(Ⅲ)──双重谱和平均功率谱的特征提取和模板图

本系列文章的工作是在舰船噪声谱图的基础上,利用模糊神经网络对舰船进行分类识别。本文是系列文章的第三篇,研究提取双重频率功率谱中调制信息的方法及建立双重谱和平均功率谱模板图。对双重谱,在每个频道中利用最小二乘法消除趋势项,对高频调制作适当补偿。包络线谱的强弱用谱线低于零频谱强度的调制深度和诺线跳出基线的相对高度来表示,并通过隶属函数转换为模糊度量。双重谱模板图记忆了稳定出现的调制线谱和相对应的调制强度。平均功率谱的模板图记忆了多个典型样本的谱均值和对应的标准离差。     

Spin-1/2 relativistic particle in a magnetic field in NC phase space

This work provides an accurate study of the spin-l/2 relativistic particle in a magnetic field in NC phase space. By detailed calculation we find that the Dirac equation of the relativistic particle in a magnetic field in noncommutative space has similar behaviour to what happens in the Landau problem in commutative space even if an exact map does not exist. By solving the Dirac equation in NC phase space, we not only obtain the energy level of the spin-1/2 relativistic particle in a magnetic field in NC phase space but also explicitly offer some additional terms related to the momentum-momentum non-commutativity.     

A new brain stimulation method: Noninvasive transcranial magneto–acoustical stimulation

We investigate transcranial magneto–acoustical stimulation(TMAS) for noninvasive brain neuromodulation in vivo.TMAS as a novel technique uses an ultrasound wave to induce an electric current in the brain tissue in the static magnetic field. It has the advantage of high spatial resolution and penetration depth. The mechanism of TMAS onto a neuron is analyzed by combining the TMAS principle and Hodgkin–Huxley neuron model. The anesthetized rats are stimulated by TMAS, resulting in the local field potentials which are recorded and analyzed. The simulation results show that TMAS can induce neuronal action potential. The experimental results indicate that TMAS can not only increase the amplitude of local field potentials but also enhance the effect of focused ultrasound stimulation on the neuromodulation. In summary, TMAS can accomplish brain neuromodulation, suggesting a potentially powerful noninvasive stimulation method to interfere with brain rhythms for diagnostic and therapeutic purposes.     

Spectral domain optical coherence tomography with sub-micrometer sensitivity for measurement of central corneal thickness

We demonstrated a method for measurement of central corneal thickness(CCT) with a sub-micrometer sensitivity using a spectral domain optical coherence tomography system without needing a super broad bandwidth light source. By combining the frequency and phase components of Fourier transform, the method is capable of measurement of a large dynamic range with a high sensitivity. Absolute phases are retrieved by comparing the correlations between the detected and simulated interference fringes. The phase unwrapping ability of the present method was quantitatively tested by measuring the displacement of a piezo linear stage. The human CCTs of six volunteers were measured to verify its clinical application. It provides a potential tool for clinical diagnosis and research applications in ophthalmology.     

复合应力场剪切诱导成型PP-R自增强管材的结构与性能研究

利用自行设计制造的剪切拉伸双向复合应力场挤管装置生产出了双向自增强的无规共聚聚丙烯(PP-R C180)管材,研究分析了该双向应力场的剪切诱导效应对PP-R C180管材的结晶熔融、取向和拉伸强度的影响.结果表明,剪切拉伸双向复合应力场的引入所带来的剪切诱导效应促进了PP-R C180分子有序性的增加,使PP-R C180体系分子更容易形成分别沿管材周向和轴向方向的取向,因而保持甚至提高了耐热性与结晶速率,降低了结晶度,改变了PP-R C180的结晶结构与形态,诱导出了全新的β晶,进而改善了管材的强度性能.与常规管材相比,自增强管材在保持其熔点不降低的前提下,使结晶度从常规管材的44.96%降至40.03%,降低了4.93%;轴向强度从常规管材的23.35 MPa最高增强到25.49 MPa,提高了9.2%;周向强度从常规管材的22.71 MPa最高增强到26.54 MPa,提高了16.9%,且增强之后管材的周向强度已经高于了轴向强度,更优化地配置了聚合物材料的性能,更充分地满足了受内压管材使用的现实需求.     

在低频振动场中注射成型HDPE试样的力学性能及其形态控制

利用自行研制的低频振动注射实验装置探讨HDPE振动注射试样力学性能和微观形态之间的关系 .实验中对常规注射和振动注射成型的试样力学性能和微观形态进行了对比实验 .SEM实验结果显示 ,振动注射制件芯层的形态由常规注射的球晶转变为垂直于振动波传递方向排列的片晶结构 ,在剪切层中同时存在串晶或柱状堆砌的片晶结构 .频率的改变 (0 相似文献   

魔芋葡甘聚糖/聚乙烯醇纳米纤维膜及其释药行为研究

为了研制药物缓释效果优良的薄膜材料,利用静电纺丝设备研制不同比重的魔芋葡甘露聚糖/聚乙烯醇纳米纤维膜,并通过扫描电镜、傅里叶变换红外光谱和示差扫描量热法表征纳米纤维膜的结构和性能,结合体外实验和数学模型研究其缓释行为.结果显示当魔芋葡甘露聚糖含量占纳米纤维膜总质量约76%时,纳米纤维膜中微纤丝粗细最均匀且结点较少,纳米纤维膜中魔芋葡甘聚糖和聚乙烯醇之间存在明显的相互作用,含有5-氨基水杨酸的纳米纤维膜在pH=7.4 PBS磷酸盐缓冲液中25 h的累积释放量大约为45%,显示出良好的药物缓释效果,其缓释行为与Higuchi模型具有较高的拟合度.研究表明利用静电纺丝设备研制的魔芋葡甘聚糖/聚乙烯醇纳米纤维膜可以为药物缓释载体的开发提供理论依据.