Determination of nicotine in tobacco with second-order spectra data of charge-transfer complex in ethanol–water binary solvents processed by parallel factor analysis

A new spectrophotometric method for the determination of nicotine in mixtures without pre-separation has been proposed. Nicotine could react with 2,4-dinitrophenol through a charge-transfer reaction to form a colored complex. The second-order data from the visible absorption spectra of the complex in a series of ethanol–water binary solvents with various water volume fractions could be expressed as the combination of two bilinear data matrices. With the bilinear model, the second-order spectra data of mixtures containing nicotine and other interferents could be analysed by using second-order calibration algorithms, and the determination of nicotine in the mixtures could be achieved. The algorithm used here was parallel factor analysis. The method has been successfully used to determine nicotine in tobacco samples with satisfactory results.     

(n-BuCp)_2TiCl_2/Sn/I_s引发合成梳形羟基功能化无规聚苯乙烯及聚合物结构与性能的研究

采用茂金属化合物(n-BuCp)2TiCl2,还原剂(Sn),引发剂苯基缩水甘油基醚甲醛共聚物(Is)组成的催化体系引发苯乙烯活性自由基聚合,合成梳形羟基功能化无规聚苯乙烯.考察了聚合温度、聚合时间及引发剂与单体的比例对苯乙烯聚合的影响.当聚合温度在65～95℃范围内,随着聚合温度的升高,聚合物的分子量及单体转化率增加;在一定温度下,聚合物的分子量与单体转化率之间存在线性增长关系,且聚合物的分子量分布较窄(Mw/Mn=1.6～1.9).采用GPC,WAXD,13C(1H)-NMR对聚合物(沸丁酮可溶级分)的结构与性能进行了表征.GPC结果证明(n-BuCp)2TiCl2/Sn/Is引发苯乙烯聚合为活性聚合;13C-NMR和WAXD结果说明聚苯乙烯链段为无规结构;1H-NMR结果表明聚合物分子链中含有羟基,并根据其结果计算出聚合物分子的臂数为4,与引发剂Is的环氧基团数相等.这些结果证明了其聚合机理是经环氧基团开环后形成的自由基引发苯乙烯自由基聚合.     

Evolution of spatial modulation of broadband laser pulses with different pulse durations in medium with non-instantaneous Kerr nonlinearity

We experimentally investigate the evolution of spatial modulation of broadband laser pulses with different pulse durations through a medium with non-instantaneous Kerr nonlinearity. By modifying the input laser pulse width, we observe the nonlinear growth of the spatial stripes that arise from interference with different modulation frequencies, and then obtain the gain spectra of the spatial modulation which clearly reveal the influence of relaxation effect on spatiotemporal modulation instability. We find that all gain spectra have the similar fastest growing frequency, but they have tails at higher frequency region in which the growth rate of gain is bigger for shorter pulse duration. The experimental results are confirmed by the perturbational analysis.     

密闭空间油页岩粉尘爆炸特性研究

为探究油页岩粉尘的爆炸特性,以龙口（Longkou, LK）、茂名（Maoming, MM）、桦甸（Huadian, HD）和抚顺（Fushun, FS）4种油页岩粉尘为研究对象,采用20 L球形爆炸装置,对这4种油页岩粉尘样品开展系统的爆炸实验,探讨油页岩粉尘的粉尘云质量浓度、粒径、挥发分、灰分、氧含量等对其爆炸特性的影响。结果表明:挥发分含量越高,油页岩粉尘的最大爆炸压力p_max、最大压力上升速率(dp/dt)_max越高,爆炸下限越低;挥发分和灰分对油页岩粉尘云爆炸分别有显著的促进和抑制作用。在37.52～106.43 μm粒径范围内,这4种油页岩粉尘样品的p_max和(dp/dt)_max均随其粉尘粒径的增大而降低,且到达最大爆炸压力的时间逐步缩短,说明小粒径油页岩粉尘较高的脱挥发速率能提高爆炸的反应程度。当粉尘质量浓度在400～2 500 g/m3范围内时,p_max和(dp/dt)_max均随粉尘云质量浓度的升高呈现先升高后降低的变化趋势,高于最佳粉尘云质量浓度（1 000 g/m3）时略有下降,但维持在较高水平,表明超过最佳质量浓度的粉尘云引燃后仍有较强的破坏力;LK样品的p_max和(dp/dt)_max均最高,分别为0.61 MPa和29.32 MPa/s,与挥发分含量相当的褐煤在同一水平,其爆炸下限为200 g/m3,在4种样品中最低,高于挥发分含量相当的褐煤;在N₂惰化条件下,LK样品的p_max和(dp/dt)_max均随环境氧含量的降低而降低,当氧含量降至15%时,系统不再发生爆炸,极限氧含量为16%。     

Determination of ATP using a double-receptor sandwich method based on molecularly imprinted membrane and fluorescence-labeled uranyl–salophen complex

A double-receptor sandwich method for the fluorescence determination of adenosine triphosphate (ATP) is proposed in this paper. The solid phase receptor on the surface of glass slides is a molecularly imprinted membrane (MIM) containing an artificial nanocavity. It is constructed by a molecular imprinting technique using adenosine monophosphate (AMP) as a template molecule. The labeled receptor is a uranyl–salophen complex containing a fluorescent group or uranyl–salophen–fluorescein (USF). It is synthesized with salophen, 5-aminofluorescein, and uranyl. In a procedure of determining ATP, ATP in sample solution is first adsorbed on the surface of the glass slide through the combination of the AMP group in ATP with the nanocavity in MIM. Then, the adsorbed ATP binds USF through the coordination reaction of the phosphate group in ATP with uranyl in USF to form a sandwich-type structure of MIM-ATP-USF. The amount of ATP is detected through the fluorescence determination of USF bound on the slide. Under optimal conditions, the linear range for the determination of ATP is 0.3 to 4.8 nmol/mL with a detection limit of 0.041 nmol/mL. The proposed method has been successfully employed for the determination of ATP in real samples with the recoveries of 98.5 to 102.5 %.     

Non-contemporaneous variations and Hlder''''s principle

In the process of deducing the Holder principle, a key step is to use the concept of non-contemporaneous variations. In this paper, whether starting from analytic method or from graphic solution method, the authors prove that the expression formula of non-contemporaneous variations is incorrect when the variable functions have zero-order nearness degree, and obtain a new expression. From the view of calculus of variations and differential calculus, the non-contemporaneous variations are studied. The study result shows that the concept of non-contemporaneous variations is a combination of the concept of variations and the concept of differentiation. The authors prove that the new expression is correct and obtain an equivalent expression of it. By means of this equivalent expression, this paper proves that the above expression formula of non-contemporaneous variations is correct when the variable functions have one-order nearness degree. Further study shows that, in the process of deducing Holder's princi