液相色谱-质谱法分析黑碳的分子标志物——苯多羧酸和硝基苯多羧酸

苯多羧酸法是定量检测黑碳和溶解态黑碳的重要分子标志物法,其中苯多羧酸和硝基苯多羧酸的分离和定量是关键环节。本文建立了苯多羧酸和硝基苯多羧酸的液相色谱-质谱分析方法,利用质谱的定性能力解决了部分苯多羧酸和硝基苯多羧酸化合物在缺乏标准品情况下的定性问题。用Phenomenex Synergi Polar RP分离柱,柱温为35 ℃,流动相为0.5%(体积分数)甲酸水溶液和甲醇,流速为0.5 mL/min,梯度洗脱,以电喷雾离子源负离子全扫描和选择扫描模式进行离子阱质谱检测,同时利用串联的二极管阵列检测器采集三维紫外光谱数据。在实际样品检测中,14个含3个及以上羧基的苯多羧酸和硝基苯多羧酸化合物获得良好分离。此方法简化并加快了苯多羧酸法定量黑碳和溶解态黑碳的分析过程,可满足环境样品中黑碳和溶解态黑碳的分析,促进了苯多羧酸法应用的普及。     

An efficient chaotic source coding scheme with variable-length blocks

An efficient chaotic source coding scheme operating on variable-length blocks is proposed.With the source message represented by a trajectory in the state space of a chaotic system,data compression is achieved when the dynamical system is adapted to the probability distribution of the source symbols.For infinite-precision computation,the theoretical compression performance of this chaotic coding approach attains that of optimal entropy coding.In finite-precision implementation,it can be realized by encoding variable-length blocks using a piecewise linear chaotic map within the precision of register length.In the decoding process,the bit shift in the register can track the synchronization of the initial value and the corresponding block.Therefore,all the variable-length blocks are decoded correctly.Simulation results show that the proposed scheme performs well with high efficiency and minor compression loss when compared with traditional entropy coding.     

高效液相色谱-柱后在线光化学衍生荧光检测法测定辣椒油中4种苏丹红染料

建立了在线光化学衍生、荧光检测、高效液相色谱(HPLC)测定辣椒油中苏丹红I、II、III和B的方法。以乙腈-水为流动相,采用梯度洗脱方式在SB-C18色谱柱上分离。用实验室自制的程序控制时间/光强光化学反应器作为在线衍生装置,优化了光衍生反应的条件和荧光检测条件。3种不同加标浓度下,辣椒油样品中4种苏丹红染料的加标回收率为81.3%～100.4%。加标水平为0.8 mg/kg下荧光信号强度的相对标准偏差(RSD,n=6)为2.6%～3.8%。苏丹红I、II、III和B的检出限(LOD)和定量限(LOQ)范围分别为0.009～0.054 mg/kg和0.030～0.181 mg/kg,优于传统的HPLC分离、二极管阵列检测器检测方法。该方法具有简单、灵敏、选择性好的特点,适用于食品样品中苏丹红的常规分析。     

聚乙烯亚胺-金属络合物的稳定常数及配位数的测定

将聚合物络合超滤(PC-UF)技术与电感耦合等离子体质谱(ICP-MS)结合, 利用化学理论计算模型, 建立了测定聚乙烯亚胺(PEI)与金属离子络合稳定常数及平均配位数的方法. 将该方法用于PEI与Cd²⁺的络合过程. 配制不同浓度比的PEI和Cd²⁺的混合溶液, 待络合反应平衡后, 用超滤离心管离心分离高分子PEI-Cd络合物, 自由离子Cd²⁺及其小分子络合物渗滤至滤液中; 用10 mL体积分数为3%稀硝酸将滤膜上截留的PEI-Cd络合物解离, 离心得到Cd²⁺的稀硝酸溶液; 用ICP-MS分别测定2次超滤后滤液中Cd²⁺的浓度, 利用化学理论模型进行计算, 得到PEI-Cd络合物的稳定常数和平均配位数. pH=4.0～5.9时, PEI-Cd络合平衡的研究结果表明, 稳定常数和平均配位数均随pH值的增大而增大, 较低程度的质子化可使PEI与Cd²⁺的络合能力增强, 络合稳定常数增大.     

Compound diffractive telescope system: design, straylight analysis, and optical test

The compound diffractive telescope is a novel space optical system which combines the structure of compound eyes with diffractive optics and so it has a lighter weight, a wider field of view (FOV), a lower cost as well as looser fabrication tolerance. In this paper, the design of a compound diffractive telescope composed of one primary lens and twenty-one eyepieces is introduced. Then the influence of diffraction orders on the performance of the system is analysed. A modified phase function model of diffractive optics is proposed to analyse the modulation transfer function (MTF) curves for 0℃ FOV, which provides a more accurate prediction of the performance of the system. In addition, an optimized mechanism is also proposed to suppress stray light. The star image and resolution tests show that the system can achieve diffraction limit imaging within ± 2℃ of FOV and ±4~mm of eccentricity. Finally, a series of pictures of an object are taken from different channels, and the splicing of pictures from adjacent FOVs is demonstrated. In summary, the designed system has been proved to have great potential applications.     

二维保单调保守恒插值算子

基于一个一维保单调保守恒插值算子,利用不完全双二次插值提出一个二维保单调保守恒插值算子.从插值逼近角度,通过几个数值实验验证该插值算子有效.用得到的二维插值算子作为结构网格自适应加密(structured adaptive mesh refinement,SAMR)算法中的细化插值算子,求解几个二维Euler方程数值例子,结果表明,提出的二维插值算子有效.     

Landau damping of collective modes in a harmonically trapped Bose--Einstein condensate

This paper proposes a method for calculating the Landau damping of a low-energy collective mode in a harmonically trapped Bose--Einstein condensate. Based on the divergence-free analytical solutions for ground-state wavefunction of the condensate and eigenvalues and eigenfunctions for thermally excited quasiparticles, obtained beyond Thomas--Fermi approximation, this paper calculates the coupling matrix elements describing the interaction between the collective mode and the quasiparticles. With these analytical results this paper evaluates the Landau damping rate of a monopole mode in a spherical trap and discusses its dependence on temperature, particle number and trapping frequency of the system.     

反相高效液相色谱法测定川楝树皮中的川楝素

川楝素是从楝属植物川楝树的韧皮或果子中分离出来的呋喃三萜类化合物,在医药上,川楝素主要用作驱蛔药,此外,它还具有明显的抗肉毒效应,能治愈致死剂量肉毒中毒的动物,在农业上,川楝素作为杀虫剂对多种害虫且有很高的活性,可用于防治各种鳞翅目幼虫,对人畜、环境及害虫天敌较为安全,故特别适用于一些重要经济作物的害虫防治,近年来,     

几个新型噁唑硼烷的制备与应用

以(1S,2S)-2-氨基-1-(4-硝基苯)-1,3-丙二醇为原料,得到四种噁唑硼烷,原? 淮呋鹜椴欢猿苹乖笆中苑蓟致哿朔从ξ露群痛呋两峁苟苑从峁挠跋臁? $601$ATwonewtypesof1,3,2-oxaborolidineswerepreparedfrom(1S,2S)-2-amino-1-(4-nitrophenyl)-propane-1,3-diolandusedascatalystsintheasymmetricreductionofacetophenone.Theinfluenceoftemperatureaswellastheeffectofthestructureofcatalystontheenantioselectivityisdiscussed.Theoriginoftheproducts'configurationalisexplored.     

利用尺度函数寻求常微分方程的近似解

论的结论是：设ｍ－１阶线性常微分方程的一般形式为ｄ＾ｍ－１ｕｄｘ＾ｍ－１＋ａ１（ｘ）ｄ＾ｍ－２ｕｄｘ＾ｍ－２＋…＋ａｍ－２（ｘ）ｄｕｄｘ＋ａｍ－１（ｘ）ｕ＝ｆ（ｘ）那么,当限定ｘ∈「０,１」时,它的近似解为ｕＮ（ｘ）＝∑２＾Ｎ－１ｋ＝－ｍ＋１ｃ＾ＮｋＮｍ（２＾Ｎｘ－ｋ）其中,ｍ≥２,Ｎｍ是ｍ阶样条函数。ｃ＾Ｎｋ是待定常数,它由ｍ－１个定解条件和导出等式产生的２＾Ｎ个条件决定。