大鼠冲击性脑创伤的太赫兹波成像检测

冲击波造成的脑创伤是目前较常见的致死致残疾病之一,对冲击性脑损伤的检测与分类具有重要意义。基于连续太赫兹波成像系统,对不同程度冲击波致伤的大鼠脑组织进行了连续太赫兹波衰减全反射成像检测,并采用支持向量机(SVM)分类器对不同创伤程度的脑组织太赫兹波成像结果进行分类识别。结果表明,太赫兹波衰减全反射成像技术可以实现对轻度、中度冲击性脑创伤脑部组织的检测。通过SVM分类器对不同创伤程度的脑部组织成像结果进行分类识别,其分类识别准确率可以达到86.36%。太赫兹波成像技术有望实现对不同程度冲击性脑创伤的早期精确检测与诊断。     

金刚石颗粒双阴极等离子溅射铬镀层显微结构研究

通过FIB-SEM观察了镀覆温度为850℃双阴极等离子溅射镀铬金刚石的表面形貌;利用TEM、XPS分析了镀层厚度、微观结构及表层元素价态;在光学显微镜下观察酸洗后金刚石的镀层变化情况。结果表明,经双阴极等离子溅射镀覆后的金刚石在其表层形成了厚度约为500 nm的柱状结构镀层,镀层晶粒尺寸约为10 nm;酸洗后镀层仅出现轻微脱落,说明金刚石铬镀层十分致密。     

周期切换下Rayleigh振子的振荡行为及机理

本文研究了自治与非自治电路系统在周期切换连接下的动力学行为及机理.基于自治子系统平衡点和极限环的相应稳定性分析和切换系统李雅普诺夫指数的理论推导及数值计算.讨论了两子系统在不同参数下的稳态解在周期切换连接下的复合系统的各种周期振荡行为,进而给出了切换系统随参数变化下的最大李雅普诺夫指数图及相应的分岔图,得到了切换系统在不同参数下呈现出周期振荡,概周期振荡和混沌振荡相互交替出现的复杂动力学行为并分析了其振荡机理.给出了切换系统通过倍周期分岔,鞍结分岔以及环面分岔到达混沌的不同动力学演化过程.     

溶剂效应对β胡萝卜素分子电子振动耦合的影响

测量了10种典型溶剂中β胡萝卜素分子的紫外-可见吸收谱和共振拉曼光谱.结果表明:溶剂的极化率、介电常数都对β胡萝卜素分子的电子-振动耦合有影响;随着极化率的增大,β胡萝卜素分子的黄昆因子、电子-振动耦合常数减小,拉曼截面增加,且这些影响与溶剂极性无关;随着溶剂介电常数的增加,对于非极性溶剂,β胡萝卜素分子的黄昆因子、电子-振动耦合常数减小,拉曼截面增加,对于极性溶剂,没有获得比较好的规律.给出了溶剂性质对电子-振动耦合的影响规律,为分子的电子-振动耦合研究中溶剂的选择提供了参考.     

CO_2和H_2O对合成气层流燃烧速度的影响

利用高速纹影摄像方法结合定容燃烧弹研究了CO_2和H_2O稀释对CO/H_2/air混合气层流燃烧速度的影响,获得了不同当量比、稀释气和CO/H_2比例下合成气的层流燃烧速度。结果表明,CO_2与H_2O对合成气层流燃烧速度的影响有显著差异。总体上来说,CO_2具有更强的稀释效果。从化学反应的角度出发,CO_2与H_2O对合成气的燃烧化学反应有着截然相反的效果,CO_2抑制燃烧化学反应,而H_2O起到促进燃烧化学反应的作用。     

Observation of Spin Polarized Clock Transition in 87Sr Optical Lattice Clock

Atomic clocks operating at optical frequencies, with much better accuracy compared with microwave atomic clocks, have been assumed to be the next- generation time and frequency standards, Many applications will benefit from this lower frequency un- certainty of optical clocks, such as the re-definition of ＇the second＇, i.e. one of the seven base units of the international system of units （SI）, test of the time variation of fundamental physical constants and rel- ativity geodesy. Recently, the neutral atom lattice clock has achieved a lower frequency uncertainty com- pared with the optical ion clock, mainly due to the im- provement of the clock laser frequency stability refer- enced to a long high-finesse ULE cavity and the more accurate evaluation of black-body radiation shift. Strontium is an excellent candidate for the neutral atom optical clock. For the fermionic isotope of stron- tium, it has intrinsically less collision shift and the first order Zeeman shift can be removed by an inter- leaved probing approach.Recently, through the pre-cise measurement of the polarizability of strontium, the black body radiation （BBR） shift of the stron- tium lattice clock, which remains to be the limitation factor of its total frequency uncertainty, is reduced to a lower 10^-18 value.The instability of the strontium lattice clock has reached 3.1 × 10-16/√T, showing the significant advantage over the single ion optical clock. The total systematic uncertainty has reached 6.4 × 10^-18 in fractional frequency, which is the best among all optical clocks until now.     

掺镁羟基磷灰石的合成及对蛋白质吸附性能的影响

采用超声化学法合成掺杂镁纳米羟基磷灰(Mg-HAP),改变羟基磷灰石纳米粒子的表面吸附性能,研究合成条件对纳米粒子对牛血清蛋白(BSA)吸附性能的影响,通过FT-IR、XRD、TEM等测试手段表征纳米粒子的化学组成、晶相和形貌,得到具有良好的生物相容性和吸附性能的掺镁羟基磷灰石。     

新型藤黄酸衍生物的合成

以藤黄酸为原料,经酯化得藤黄酸甲酯(2);通过对2的6-位酚羟基进行结构修饰,合成了5个新型的藤黄酸衍生物,其结构经1H NMR和IR表征。     

新型含吡唑基的查尔酮的合成、表征及晶体结构

以2种1-苯基-3-甲基-5-对甲苯氧基-吡唑-4-甲醛为原料, 在强碱条件下与苯乙酮(取代苯乙酮)发生羟醛缩合, 高产率地合成出10种新型含吡唑基的查尔酮. 化合物的结构经元素分析, IR和¹H NMR确认. 并用X射线衍射法测定了化合物4c的晶体结构. 化合物4c属三斜晶系, 空间群P-1, 晶胞参数: a＝1.0225(2) nm, b＝1.4263(3) nm, c＝1.6718(3) nm, α＝110.32(3)°, β＝106.30(3)°, γ＝98.11(3)°, M_r＝428.90, V＝2.1159(7) nm³, D_c＝1.346 Mg/m³, Z＝2, F(000)＝896.     

Difference in effect of temperature on absorption and Raman spectra between all-trans-β-carotene and all-trans-retinol

<正>Temperature dependencies(81℃-18℃) of visible absorption and Raman spectra of all-trans-β-carotene and all-trans-retinol extremely diluted in dimethyl sulfoxide are investigated in order to clarify temperature effects on different polyenes.Their absorption spectra are identified to be redshifted with temperature decreasing.Moreover, all-trans-β-carotene is more sensitive to temperature due to the presence of a longer length of conjugated system.The characteristic energy responsible for the conformational changes in all-trans-β-carotene is smaller than that in all-transretinol. Both of the Raman scattering cross sections increase with temperature decreasing.The results are explained with electron-phonon coupling theory and coherent weakly damped electron-lattice vibrations model.