桑葛降糖粉对四氧嘧啶模型小鼠降糖作用的研究

目的研究保健食品桑葛降糖粉对四氧嘧啶糖尿病模型小鼠皀辅助降血糖作用。方法随机选取10只小鼠为空白组,以四氧嘧啶建立糖尿病小鼠实验组,随机分配为模型组、阳性对照组[3g/(kg×d)]、桑葛降糖粉高、中、低剂量组[7.8、3.9、1.95g/(kg×d)],灌胃给药15d,每次灌胃量均为0.1mL/10g。分别在试验第3、7、11、15d测定各组小鼠皀体重、饮水量和空腹血糖值(fastingbloodglucose,FBG)。在第16d迚行口服葡萄糖耐量试验,分别测定各组小鼠口服葡萄糖0、30、60、120min后皀血糖值,幵计算曲线下面积(areaunderthecurve,AUC)。结果桑葛降糖粉对糖尿病小鼠皀体重影响不显著,但其多饮症状得到明显改善;桑葛降糖粉高、中剂量组均能显著降低小鼠FBG(P0.05),且能显著增加小鼠皀糖耐量(oralglucosetolerance,OGT)(P0.01)。结论桑葛降糖粉能够明显改善糖尿病小鼠皀病症,可以有效降低糖尿病小鼠皀FBG和增加其OGT,因此具有较好皀辅助降血糖作用。     

高效液相色谱-高分辨质谱法定性筛查牛奶中49种β-内酰胺类抗生素残留

目的 开发和验证定性筛查牛奶中49种β-内酰胺类抗生素残留的高效液相色谱-高分辨质谱法(high performance liquid chromatography coupled with high resolution mass spectrometry,HPLC-HRMS)。方法牛奶经磷酸盐缓冲液及乙腈提取后,加入硫酸钠(Na2SO4)和氯化钠(NaCl)进行盐析,离心后取部分上清液经Na2SO4和C18混合的分散式固相萃取填料(dispersive solid phase extraction,d-SPE)净化,净化液浓缩定容后,使用HPLC-HRMS分别以全扫描-数据依赖型二级扫描(full scan-data dependent secondary acquisition,Full MS/dd-MS2)和全扫描-平行反应监测二级扫描(full scan-selected ion monitoring/parallel reaction monitoring,Full MS/PRM)两种模式进行数据采集。结果在Full MS/PRM模式下,45种抗生素通过方法验证,假阳性率和...     

普适计算的隐私保护协议

改进了一个用于保护用户隐私的安全协议。该协议引入了服务发现者,用户并不直接与服务提供者进行通信,而是通过服务发现者来完成用户的需求。通过对协议的安全分析,可以看出：该协议保护了用户的隐私,也防止了用户被跟踪,并且减少了原有协议的计算量,更适合普适计算。该协议可以很好的保护用户的隐私,并且能够防止重放攻击。     

Synthesis and photocatalytic activity of titania microspheres with hierarchical structures

A combined sol-gel and solvothermal process was introduced to fabricate the titania microspheres with hierarchical structures by using lauryl alcohol as the structure-directing agent. Scanning electron microscope, high-resolution transmission electron microscope, Fourier transform infrared spectrograph and powder X-ray powder diffraction indicated that the molar ratio of lauryl alcohol, water and tetra-n-butyl titanate was the key factor for the formation of the mono-dispersed titania with anatase phase and the optimal ratio was 1.2:4:1. The diameter of the end-product was 523 ± 74 nm and it was composed of smaller nanoparticles with about 6.8 nm size in diameter. Photocatalytic activity of the end-product was investigated by employing Rhodamine B and Methylene blue as the model compounds. The target microspheres exhibited the higher photocatalytic efficiency compared with commercial Degussa P25 titania and this result might be due to the hierarchical structures of microspheres according to the analysis of Brunauer-Emmett-Teller specific surface areas.     

High organosolubility and optical transparency of novel polyimides derived from 2′,7′-bis(4-amino-2-trifluoromethylphenoxy)-spiro (fluorene-9,9′-xanthene)

A novel spiro(fluorene-9,9′-xanthene) skeleton bis(ether amine) monomer, 2′,7′-bis(4-amino-2-trifluoromethylphenoxy)-spiro(fluorene-9,9′-xanthene), was prepared through a simple acid-catalyzed condensation reaction of 9-fluorenone with resorcinol to form the spiro framework through an sp³ carbon atom. Subsequent nucleophilic substitution reaction of spiro[fluorene-9,9′-(2′,7′-dihydroxyxanthene)] with 2-chloro-5-nitrobenzotrifluoride in the presence of potassium carbonate in N,N-dimethylacetamide, was followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new polyimides were synthesized from the diamine with various commercially available aromatic tetracarboxylic dianhydrides via a conventional two-stage process with the thermal or chemical imidization of the poly(amic acid) precursors. Most of the polyimides obtained from both routes were soluble in many organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide and m-cresol. All the polyimides could afford transparent, flexible, and strong films with low moisture absorptions of 0.35–0.64% and low dielectric constants of 2.63–3.09 at 1 kHz. Thin films of these polyimides showed an UV–vis absorption cutoff wavelength at 356–384 nm, and those of polyimides from 4,4′-oxydiphthalic dianhydride and 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) were essentially colorless. The polyimides exhibited excellent thermal stability, with decomposition temperatures (at 10% weight loss) above 540 °C in both air and nitrogen atmospheres and glass transition temperatures (T_g) in the range of 274–323 °C.     

裂纹长度对PBX代用材料表观断裂韧性Kc的影响

表观断裂韧性（K_c）是表征高聚物粘结炸药（PBX）抵抗裂纹萌生和裂纹扩展的重要材料性能,研究表观断裂韧性K_c的尺寸效应对预测不同尺度的PBX的起裂及失效行为具有重要意义。通过中心裂纹巴西圆盘（CSTBD）试验,对PBX代用材料的表观断裂韧性K_c的尺寸效应特性进行研究,通过断裂试验研究了不同裂纹长度（2,4,6,8,10 mm）对CSTBD试样表观断裂韧性K_c的影响。并采用了传统的最大切应力（MTS）准则以及考虑Willimas级数高阶项系数和断裂扩展区（FPZ）长度预估模型的修正最大切应力（MMTS）准则,对PBX代用材料的表观断裂韧性K_c的尺寸效应解释。结果发现,随着裂纹长度的增加,K_c从0.139 MPa·m^0.5增长至0.251 MPa·m^0.5,并且随着裂纹长度的增加K_c趋于稳定。在使用A₃项修正的FPZ长度预估模型下,相较于传统的MTS准则,使用MMTS准则能够很好地解释PBX代用材料表观断裂韧性K_c的尺寸效应。     

Blood compatibility of zinc–calcium phosphate conversion coating on Mg–1.33Li–0.6Ca alloy

Magnesium alloys as a new class of biomaterials possess biodegradability and biocompatibility in comparison with currently used metal implants. However, their rapid corrosion rates are necessary to be manipulated by appropriate coatings. In this paper, a new attempt was used to develop a zinc-calcium phosphate (Zn-Ca-P) conversion coating on Mg-1.33Li-0.6Ca alloys to increase the biocompatibility and improve the corrosion resistance. In vitro blood biocompatibility of the alloy with and without the Zn-Ca-P coating was investigated to determine its suitability as a degradable medical biomaterial. Blood biocompatibility was assessed from the hemolysis test, the dynamic cruor time test, blood cell count and SEM observation of the platelet adhesion to membrane surface. The results showed that the Zn-Ca-P coating on Mg-1.33Li-0.6Ca alloys had good blood compatibility, which is in accordance with the requirements for medical biomaterials.     

无线传感器网络中支持并行传输的信道与功率联合优化博弈算法

针对无线传感器网络中干扰日益增大引起网络容量下降、能耗增加的问题,该文建立了信道分配与功率控制联合优化博弈模型。在该模型中链路将既能保持自身成功传输又不影响其它链路传输的信道作为可选信道,以实现链路的并行传输。继而基于该模型设计了一种支持并行传输的信道分配与功率控制联合优化博弈算法(JCPGC)。该算法利用最佳响应策略对模型求解,并通过超模博弈等理论证明了JCPGC能够收敛到纳什均衡。此外,该算法充分考虑信道分配和功率控制之间独立又相互影响的关系提高了网络容量。仿真实验结果表明,JCPGC具有大容量、低干扰和低能耗的特性。     

针对遥感图像压缩的改进SPIHT 算法

在研究遥感图像和小波分解系数特点的基础上,提出了一种改进的SPIHT算法：对第一阶小波变换产生的低频子带和高频子带进行小波再分解,并对再分解后的四个子带,取不同的门限值,分别进行编码;再分解后的高频子带小波系数不进行编码,在解码时直接赋予固定值重构图像。改进算法更好地处理了低频子带和高频子带的小波系数,对遥感图像的压缩实验证实了改进算法的有效性。     

Sorption of nitrate onto amine-crosslinked wheat straw: characteristics, column sorption and desorption properties

The nitrate removal process was evaluated using a fixed-bed column packed with amine-crosslinked wheat straw (AC-WS). Column sorption and desorption characteristics of nitrate were studied extensively. Solid-state (13)C NMR and zeta potential analysis validated the existence of crosslinked amine groups in AC-WS. Raman shift of the nitrate peaks suggested the electrostatic attraction between the adsorbed ions and positively charged amine sites. The column sorption capacity (q(ed)) of the AC-WS for nitrate was 87.27 mg g(-1) in comparison with the raw WS of 0.57 mg g(-1). Nitrate sorption in column was affected by bed height, influent nitrate concentration, flow rate and pH, and of all these, influent pH demonstrated an essential effect on the performance of the column. In addition, desorption and dynamic elution tests were repeated for several cycles, with high desorption rate and slight losses in its initial column sorption capacity.