N,S-CDs的制备及在检测生物硫醇方面的应用

以柠檬酸和硫脲为碳源,采用固相合成法一步制备共掺杂碳点,该氮、硫共掺杂碳点在440 nm处发射强荧光(λ_ex=361 nm),相对荧光量子产率为23.69%。研究发现,当Hg²⁺存在时,其水溶液能发生明显的荧光淬灭。向N,S-CDs溶液中加入不同浓度的Hg²⁺标准溶液后,通过线性拟合曲线求出最低检出限为34.2 nmol/L;由于生物硫醇可以很好地结合Hg²⁺,所以向N,S-CDs-Hg²⁺体系中加入谷胱甘肽(GSH)或半胱氨酸(Cys),可观察到溶液的荧光明显恢复。基于此本文设计了一种“on-off-on”荧光探针用于GSH和Cys的检测,最低检出限分别能达到27 nmol/L和15 nmol/L。     

谱分析和带限外推的新算法

付氏分析和谱估计的一个中心问题是根据信号f(t)的有限段来确定其变换:F(ω)=∫_-∞^∞f(t)e^-jωtdt(1)     

纸张荧光增白剂对色彩复制的影响研究

目的 探究纸张荧光增白剂含量(OBA)对色彩复制的影响,有利于准确测量颜色并实现色彩在不同设备间正确转换,准确复制颜色。方法 选择含较多荧光增白剂、含少量荧光增白剂、不含荧光增白剂3种类型的纸张,分别基于M1/M2的观察条件,测量纸白、CMYK线性色表以及IT8.7/4色表,分析M1/M2观察条件下Δb^*、ΔE^*值以及ICC曲线变化趋势。结果 在M1和M2观察条件下测量纸张基色b^*值的差值绝对值可以确定基材中的OBA的含量,且OBA含量对颜色测量数据的影响与阶调值相关,基本呈负线性关系;在M1观察条件下测量数据生成ICC色彩特性文件,整体线性偏移蓝色,即b^*值往负值线性偏移。结论 基于M1观察条件的色彩管理流程,需进一步研究荧光增白剂含量对b^*值进行线性补偿校正的影响,从而减少纸张荧光增白剂对色彩管理的影响,使纸张上的颜色复制达到理想状态。     

樟子松基碳量子点的制备工艺优化

目的 将樟子松木材包装废弃物转化为荧光碳量子点,为实现废弃樟子松木材包装的高值化综合利用探索一条新途径。方法 以60目樟子松木材包装废弃物为碳量子点前驱体,分别以硫酸和乙二胺为硫和氮掺杂剂,在温度为200 ℃、时间为10 h的水热条件下合成樟子松基碳量子点。采用紫外可见光分光光度计、荧光分光光度计、透射电子显微镜、傅里叶红外光谱仪和X射线光电子能谱仪等表征手段,研究原材料配比对所制备樟子松基碳量子点物理结构、化学结构和光学性质的影响,并以碳量子点的荧光量子产率为评价指标,优化樟子松基碳量子点的制备工艺。结果 所得硫氮掺杂碳量子点呈规则球形,其平均粒径及粒径分布分别为4.30 nm和2.01~6.63 nm;当原材料配比为m(樟子松木粉)∶m(硫酸)∶m(乙二胺)=1∶1∶1时,合成的掺杂碳量子点的荧光最强、荧光量子产率最高。当樟子松木粉、去离子水、硫酸和乙二胺的质量比为1.250∶50∶1.250∶1.250时,掺杂碳量子点的荧光量子产率比未掺杂碳量子点的高约80倍。结论 将樟子松木材包装废弃物转化为荧光碳量子点,是实现废弃樟子松木材包装的高值化综合利用的新途径。     

Preferred orientation of AlN plates prepared by chemical vapour deposition of AlCl3 + NH3 system

Aluminium nitride (AlN) plates about 1 mm thick (maximum) were prepared by chemical vapour deposition (CVD) at the maximum deposition rate of 430 nm s⁻¹ using AlCl₃, NH₃ and H₂ gases at deposition temperatures,T _dep, of 873–1473 K. The effects of deposition conditions on the preferred orientation, morphology and micro-structure were investigated. WhenT _dep was less than 1073 K, the resulting CVD AlN plates contained some impurity chlorine and the aluminium content exceed the nitrogen content. WhenT _dep exceeded 1173 K, no chlorine was detected, and the Al/N atomic ratio matched the stoichiometric value. The lattice parameters (a=0.311 nm,c=0.4979 nm) and density (3.26×10³ kgm⁻³) were in agreement with values reported previously. The crystal planes oriented parallel to the substrates changed from (1 1 ˉ2 0) to (1 0 ˉ1 0) to (0001) with increasing total gas pressure (P _tot) and decreasingT _dep. This tendency is discussed thermodynamically and is explained by the change of supersaturation in the gas phase.     

Kinetics of Technetium Reactions: XV. Tc(IV) Oxidation with Persulfate Ions in HClO<Subscript>4</Subscript> Solution

Tc(IV) is oxidized with persulfate ions in HClO₄ solution by reactions with both S₂O ₈ ²⁻ ion and product of its thermal decomposition, Caro acid, H₂SO⁵. The reaction rate at 35°C and solution ionic strength μ = 1 is described by the equation d[Tc(IV)]/dt = k ₁[Tc(IV)][S₂O ₈ ²⁻ ] + k ₃[Tc(IV)][HSO ₅ ⁻ ]/[H⁺], where k ₁ = 0.88±0.04 l mol⁻¹ min⁻¹ and k ₃ = 110±5 min⁻¹. With increasing ionic strength to μ = 2, both rate constants decrease (k ₁ = 0.58±0.08 l mol⁻¹ min⁻¹ and k ₃ = 52±2 min⁻¹ at 35°C). The activation energy of the overall reaction is 77.7±8.1 kJ mol⁻¹. The mechanisms of both reactions are discussed. __________ Translated from Radiokhimiya, Vol. 47, No. 2, 2005, pp. 145–149. Original Russian Text Copyright ? 2005 by V. Koltunov, Gomonova, G. Koltunov.     

Insulating ZnO film on silicon for MIS application

High resistive zinc oxide thin film (∼ 0·5 μm) was deposited on single crystalp-silicon (100) wafers by an inexpensive spray-CVD method and was characterized both optically and electrically. Al/ZnO/Si (MIS) device structure was subsequently fabricated and bothI − V andC − V characteristics were studied. The semiconductor-insulator interface charge density (D _it) was calculated by Terman method and was found to be 3·85 × 10¹¹ cm⁻²eV⁻¹.     

铝酸钙基稀土荧光粉CaAl4O7∶Eu3+的制备及热稳定性研究

在目前商用白光LED的实际应用中,存在发光色温高、显色指数低及热稳定性差等问题。为了改进白光LED存在的不足,使其更适用于人类生活的需求,本文通过共沉淀法合成了一系列CaAl₄O₇∶Eu^{3+高温红光荧光粉,采用扫描电子显微镜、X射线衍射仪、能谱仪分别对样品的形态、结构、组成元素及分布进行表征,并通过荧光光谱仪对CaAl₄O₇∶Eu3+的荧光特性及热稳定性进行了研究。实验结果表明,最佳样品为CaAl₄O₇∶0.02Eu3+}。其激发光谱中,在 393及464 nm处有两个强光激发峰,分别属于⁷F₀→⁵L₆及⁷F₀→⁵D₂跃迁；在发射光谱中,最强发射峰位于612 nm,为⁵D₀→⁷F₂跃迁的窄带红光发射；最佳样品的发光具有负的热猝灭效应,其在90 ℃时发射光强度最大,此时积分荧光发射强度为30 ℃时初始值的114.5%。当测试温度升高至150 ℃时,积分荧光发射强度仍为初始值的108%；在CaAl₄O₇∶0.02Eu^{3+的原型红光LED的电致发光测试中,发射红光比随着驱动电流的增大而增大。CaAl₄O₇∶0.02Eu3+}荧光粉具有优异的高温荧光特性,满足LED对荧光粉的发光热稳定性的要求,表明其在WLEDs领域具有潜在的应用前景。     

Photoelectrochemical investigation on spray depositedn-CdIn2S4 thin films

Polycrystalline thin films ofn-CdIn₂S₄ have been spray deposited onto amorphous and fluorinedoped tin oxide (FTO) coated glass substrates at the optimized substrate temperature of 380°C. The films were characterized by X-ray diffraction (XRD) and optical absorption studies. XRD studies revealed that the films were polycrystalline with spinel cubic structure. The optical absorption studies showed the band gap energy to be 2·14 eV. Photoelectrochemical (PEC) investigations were carried out using cell configurationn-CdIn₂S₄/1 M NaOH+1 M Na₂S+1 M S/C. Using Butler model, the optical band gap and minority carrier diffusion length (L _P) were found to be 2·22 eV and 0·07 μm, respectively. Gartner’s model was used to calculate the minority carrier diffusion length and the donor concentration (N _D) for CdIn₂S₄ films at three different wavelengths.N _D was found to be of the order of 10¹⁶ cm⁻³.     

薄膜包装对鲜切生菜货架期品质的影响

目的 探究不同薄膜包装对鲜切生菜货架期色泽和营养品质的影响,以期为鲜切生菜的保鲜提供便捷高效的方法。方法 本研究采用不同厚度(20、30和40 μm)的聚乙烯(PE)薄膜以及微孔PE薄膜包装鲜切生菜,于(4±1)℃条件下模拟货架8 d,以带孔PE薄膜包装作为对照组,研究这5种薄膜包装对鲜切生菜货架期间表型、感官评分、质量损失率、袋内O2和CO2、色差、叶绿素、类胡萝卜素、叶黄素、可滴定酸、抗坏血酸(VC)和丙二醛(MDA)含量的影响。结果 不同厚度的PE薄膜以及微孔PE薄膜包装能在一定程度上减少鲜切生菜色泽的变化、质量损失率的上升以及营养成分的损失。其中,20 μm薄膜和微孔膜包装可以显著抑制鲜切生菜质量损失率,a^*、b^*和MDA的升高,保持袋内较高的O2,并抑制CO2的积累,减缓叶绿素、类胡萝卜素、叶黄素、可滴定酸、抗坏血酸和感官评分的下降,进而维持较高的品质,延长货架期。与20 μm薄膜相比,微孔膜会造成鲜切生菜相对较高的质量损失率。结论 20 μm厚度的PE薄膜更适合作为鲜切生菜保鲜的包装材料,可延长货架期2~3 d。本研究为鲜切生菜保鲜包装袋的选择提供依据,推动鲜切预制菜产业的发展。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。     

Assurance of the Uniformity of Measurements of the Power of Laser Radiation

On the basis of an analysis of the principle underlying the construction of standards and systems designed for reproduction of the unit of mean power and energy of laser radiation, it is shown that these standards consist of unified subsystems that carry the principal metrological load. By means of such a division, it is possible to realize a systems-engineering synthesis of standards with preassigned error. __________ Translated from Izmeritel'naya Tekhnika, No. 11, pp. 20–23, November, 2005.     

Assurance of the Uniformity of Measurements of Energy of Short-Pulse Coherent Radiation

Ways of creating unified automatized reference (calibration) and standard measurement equipment for the purpose of developing a subsystem for the assurance of the uniformity of measurements of the energy of short-pulse laser radiation are considered. __________ Translated from Izmeritel'naya Tekhnika, No. 11, pp. 24–28, November, 2005.     

方波幅度的测量不确定度

介绍了用众数法评价方波幅度时的不确定度分析和评价过程;讨论了主要的不确定度来源,包括众数判别区间的影响、波形测量系统幅度测量误差的影响等等;给出了减小不确定度的主要措施,并结合一个实例,给出了方波幅度的不确定度评价结果。     

水线震荡对斜拉桥拉索风雨激振稳定性的作用

从理论和试验两个方面研究了水线震荡对斜拉桥拉索风雨激振稳定性的作用。建立了拉索和水线的运动方程，应用李雅普诺夫函数给出了水线不平衡角的判别公式。设计了一种新型的带有可运动人工水线的拉索模型，并进行了风洞试验。理论和试验结果表明，水线震荡是导致拉索风雨激振具有较大不稳定范围的主要原因。试验结果证明了理论模型和分析的结果是正确的。     

二硝基重氮酚重氮化反应机理再探

文中依据杂化理论分析了亚硝酸的结构特点，主要以分子结构理论为基础，从理论上指出在ＤＤＮＰ重氮化反应中，可能是氯化亚硝酰作为重氮反应的亲电试剂，其进攻发生在氨基的氮上，从而推测了获得ＤＤＮＰ的反应历程。     

逻辑分析仪部分参数测量结果的不确定度评定

介绍了逻辑分析仪部分参数测量结果的不确定度分析评定方法,评定过程及结论,可应用在对于计量标准进行相应指标的不确定度评定分析上。     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Calculation of the Heat of Combustion of Hydrocarbon Components of Fuels

Development is continued of the empirical method for the calculation of the heat of combustion of organic compounds and, in particular, of hydrocarbons of different structures by the additive scheme based on their chemical structure.