带正电荷蛋白在纳米/微米草酸钙晶体上的吸附特性及其与带负电荷蛋白吸附的比较

研究尺寸分别为100 nm和3μm的一水草酸钙(COM)和二水草酸钙(COD)晶体对带正电荷的蛋白溶菌酶(LSZ)的吸附差异,并与带负电荷的蛋白牛血清白蛋白(BSA)的吸附进行了比较。LSZ在纳米/微米COM和COD晶体上的吸附都很好的拟合了Langmuir模型,属于单分子层吸附。纳米/微米COM和COD对LSZ的最大吸附量顺序为COD-100 nmCOM-100 nmCOD-3μmCOM-3μm;晶体的比表面积越大,曲率越小,晶体表面所带电荷越负,晶体结晶水越多,均导致LSZ吸附量越大。体系离子强度和p H值亦影响LSZ的吸附。随着Na Cl浓度增加,LSZ的吸附量减小,说明Na+离子能与带正电荷的蛋白LSZ竞争晶体表面的吸附位点,导致晶体表面吸附LSZ的位点减少。晶体对LSZ的最大吸附量都出现在LSZ的等电点附近(p H=10.7);在p H=5~8(生理条件)时,LSZ的吸附量随p H值的增大而增大。本文结果提示,通过减小尿液的p H值或者适当增大尿液的离子强度,可以减小LSZ在尿微晶上的吸附量,有可能达到抑制草酸钙结石的效果。     

由联苯四羧酸配体构筑的一维锰(Ⅱ)和二维铜(Ⅱ)配位聚合物的合成、晶体结构及磁性质

采用水热方法,用2种联苯四羧酸配体（2,4-H₄bpta和3,5-H₄bpta）和4,4''-联吡啶（4,4''-bipy）或2,2''-联吡啶（2,2''-bipy）分别与MnCl₂·4H₂O和CuCl₂·H₂O反应,合成了一个具有一维双螺旋链结构的配位聚合物[Mn（μ₃-2,4-H₂bpta）（4,4''-bipy）₂]_n（1）和一个二维层状配位聚合物{[Cu（μ4-3,5-bpta）_0.5（2,2''-bipy）（H₂O）]·H₂O}_n（2）,并对其结构和磁性质进行了研究。结构分析结果表明2个配合物分别属于单斜晶系,P2₁/c和C2/c空间群。配合物1具有一维双螺旋链结构,而且这些一维链通过O-H…N氢键作用进一步形成了二维超分子网络。而配合物2具有二维层状结构。研究表明,配合物1中相邻锰离子间存在铁磁相互作用。     

基于多尺度传递熵的脑肌电信号耦合分析

神经运动控制中脑肌电同步特征可以反映皮层与肌肉之间的功能联系. 为定量研究脑电和肌电信号在不同时间尺度上的同步耦合特征, 提出多尺度传递熵方法实现静态握力输出下的脑肌电耦合分析: 对同步采集的头皮脑电信号(EEG) 和表面肌电信号(EMG)进行多尺度化, 计算不同尺度因子下EEG与EMG间的传递熵值, 获取不同耦合方向(EEG→EMG及EMG→EEG)上的非线性脑肌电耦合特征; 进一步计算功能频段下的显著性面积指标, 定量分析不同尺度下皮层肌肉功能耦合强度的差异. 分析结果显示, 静态握力输出时beta频段(15–35 Hz)皮层肌肉功能耦合特征显著, 且beta2频段(25–35 Hz)在不同尺度上EEG→EMG方向的耦合强度大于EMG→EEG方向, 耦合强度最大值和方向间耦合强度差异显著值均出现于较高时间尺度. 研究结果揭示: 皮层肌肉功能耦合具有双向性, 且耦合强度在不同时间尺度和不同功能频段上有所差异, 可利用多尺度传递熵定量刻画大脑皮层与肌肉之间的非线性同步特征及功能联系.     

液相色谱-电喷雾-四级杆-飞行时间质谱法分析琼胶寡糖

建立超高效液相色谱-电喷雾-四级杆-飞行时间质谱联用技术快速分离鉴定琼胶寡糖的方法.通过分析比较3种色谱柱(BEH Amide、BEH C8及Atlantis T3)对琼胶寡糖的分离结果发现,Amide色谱柱具有最佳优势,在无需样品衍生的状态下,可使聚合度介于3～29的琼胶寡糖得以良好分离,分析迅速,灵敏度高.而衍生后...     

Synthesis, structure and magnetic properties of a novel family of heterometallic nonanuclear Na(I)2Mn(III)6Ln(III) (Ln = Eu, Gd, Tb, Dy) complexes

The structures and magnetic properties of four isomorphous nonanuclear heterometallic complexes [Na(2){Mn(3)(III)(μ(3)-O(2-))}(2)Ln(III)(hmmp)(6)(O(2)CPh)(4)(N(3))(2)]OH·0.5 CH(3)CN·1.5H(2)O are reported, where Ln(III) = Eu (1), Gd (2), Tb (3) and Dy (4), H(2)hmmp = 2-[(2-hydroxyethylimino)methyl]-6-methoxyphenol. Complexes 1-4 were prepared by the reactions of hmmpH(2) with a manganese salt and the respective lanthanide salt together with NaO(2)CPh and NaN(3). Single-crystal X-ray diffraction analyses reveal that the six Mn(III) and one Ln(III) metal topology in the aggregate can be described as a bitetrahedron. The two peripheral [Mn(III)(3)(μ(3)-O(2-))](7+) triangles are each bonded to a central Ln(III) ion with rare distorted octahedral geometry. The magnetic properties of all the complexes were investigated using variable temperature magnetic susceptibility and both antiferromagnetic and ferromagnetic interactions exist in the [Mn(III)(3)(μ(3)-O(2-))](7+) triangle. Weak ferromagnetic exchange between the Ln(III) and Mn(III) ions has been established for the corresponding Gd derivative. The Gd, Tb and Dy complexes show no evidence of slow relaxation behaviour above 2.0 K.     

Thermal behavior of 1,2,3-triazole nitrate

The thermal decomposition behaviors of 1,2,3-triazole nitrate were studied using a Calvet Microcalorimeter at four different heating rates. Its apparent activation energy and pre-exponential factor of exothermic decomposition reaction are 133.77 kJ mol⁻¹ and 10^14.58 s⁻¹, respectively. The critical temperature of thermal explosion is 374.97 K. The entropy of activation (ΔS ^≠), the enthalpy of activation (ΔH ^≠), and the free energy of activation (ΔG ^≠) of the decomposition reaction are 23.88 J mol⁻¹ K⁻¹, 130.62 kJ mol⁻¹, and 121.55 kJ mol⁻¹, respectively. The self-accelerating decomposition temperature (T _SADT) is 368.65 K. The specific heat capacity was determined by a Micro-DSC method and a theoretical calculation method. Specific heat capacity equation is C_\textp ( \textJ mol ^{- 1} \text K ^{- 1} ) = - 42.6218 + 0.6807T C_{\text{p}} \left( {{\text{J mol}}^{ - 1} {\text{ K}}^{ - 1} } \right) = - 42.6218 + 0.6807T (283.1 K < T < 353.2 K). The adiabatic time-to-explosion is calculated to be a certain value between 98.82 and 100.00 s. The critical temperature of hot-spot initiation is 637.14 K, and the characteristic drop height of impact sensitivity (H ₅₀) is 9.16 cm.     

Syntheses of Chiral Acyclic Natural Products from Sugar

The syntheses of several biologically interesting acyclic natural products such as LTA, 1, LTB₄ 8, mosquito oviposition attractant pheromone 46 and cytotoxic annonaceous acetogenin corossolone 57 and corossoline 58 from sugars in our laboratory are reviewed.     

Microstructure and anti-oxidation property of CrSi2-SiC coating for carbon/carbon composites

To protect carbon/carbon (C/C) composites from oxidation, a new type of oxidation protective coating has been produced by a two-step pack cementation technique. XRD and SEM analysis show, the coating obtained by the first step pack cementation was a porous β-SiC structure, and a new phase of CrSi₂ was generated in the porous SiC coating after heat-treatment according to the second step pack cementation process. Oxidation test shows that, the weight loss of the SiC coated C/C is up to 11.26% after 5 h oxidation in air at 1773 K, and the weight loss of the CrSi₂-SiC coated C/C composites is only 4.15% after oxidation in air at 1773 K for 34 h. The oxidation of C/C composites was primarily due to the reaction of C/C matrix and oxygen diffusing through the penetrable cracks in the coating.     

汽车尾气颗粒物的STXM和NEXAFS研究

为了研究汽车尾气颗粒物的结构和氮的种态,使用扫描透射X射线显微成像(STXM)技术研究了桑塔纳3000和高尔汽车尾气颗粒物.STXM表明单颗粒物的粒径为500nm,颗粒物质量分布不均匀,有中间空洞.比较汽车尾气颗粒物和(NH4)2SO4和NaNO3中N的1sX射线近边吸收精细结构谱(NEXAFS),铵盐在406eV有显著的σ*吸收峰,有肩部结构;汽车尾气颗粒物和NaNO3中N的近边吸收谱在412eV和418.5eV有明显的σ吸收峰;(NH4)2SO4中N的近边吸收谱在413.5eV和421.8eV更宽的σ吸收峰.硝酸盐是汽车尾气颗粒物中的N化学种态的主要存在形式.在395—418eV能量范围内对桑塔纳3000汽车尾气颗粒物进行堆栈扫描,经过主成分分析和聚类分析,发现其表层主要为硝酸盐,内部有少量铵盐.     

6-NO_2-BTAMB与钴显色反应的研究与应用

研究了6-NO2-BTAMB与钴显色反应。实验表明,在pH6.2—7.4(CH2)6N4-HCl体系中,钴与试剂定量地形成稳定的蓝绿色络合物,表观摩尔吸光系数ε650=1.18×105L·mol-1.cm-1;钴浓度在0—6μg/10mL范围内符合比耳定律。用于VB12和钴分子筛中微量钴的测定,结果令人满意。