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951.
气相色谱法同时测定塑料食品包装袋中4种有机残留物 总被引:7,自引:0,他引:7
食品塑料包装袋中的有机残留物甲苯是一种对人体有害的化合物.包装食品用的塑料制品.其含量为卫生和食品监督部门所严格控制.其中的异丙醇、丁酮和乙酸乙酯虽毒性不大,但它们的大量使用以及在环境中的行为不甚明了,因此建立一种同时测定4种组分的分析方法是十分必要的.有关顶空气相色谱法同时测定食品塑料包装袋中的4种残留组分的研究还未见报道.本文研究了一种简便、快速、准确的静态顶空气相色谱法,可同时测定塑料食品包装袋中的甲苯、异丙醇、丁酮和乙酸乙酯.该法操作简便,灵敏度高,重现性好,结果令人满意. 相似文献
952.
An MgZnAl-CO3 layered double hydroxide (LDH) slurry with Na2 SO4 as the by-product has been prepared by a co-precipitation method.The filtrates in the LDH washing process were collected according to their different levels of salinity.Filtrates with lower salinity can be used to wash a LDH slurry with higher salinity in the next cycle.Only in the final stages is pure water used.Recycling of the wash water in this way has been employed in a commercial production process,resulting in a water-saving of over 80%.The resulting MgZnAl-CO3-LDH product has a well-formed crystalline layered structure with a low content of impurities. 相似文献
953.
Xiangyu Xu Dianqing Li Jiaqing Song Yanjun Lin Zhi Lv Min Wei Xue Duan 《Particuology》2010,8(3):198-201
A clean method for preparing layered double hydroxides (LDHs) has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reaction. The reactions were carried out under hydrothermal conditions in either a high pressure autoclave or a microwave digester. The compositions, structural parameters and thermal behavior of the resulting LDHs are very similar to those of materials produced by using the separate nucleation and aging steps (SNAS) method. The major advantage of the new method is that no by-product is produced, so that filtration and washing processes are unnecessary. The consequent reduction in water consumption is beneficial to the environment. 相似文献
954.
We consider the space D(X, Y) of densely continuous forms introduced by Hammer and McCoy [5] and investigated also by Holá [6]. We show some additional
properties of D(X, Y) and investigate the subspace D*(X) of locally bounded real-valued densely continuous forms equipped with the topology of pointwise convergence τ-
p
. The largest part of the paper is devoted to the study of various cardinal functions for (D*(X), τ
p
), in particular: character, pseudocharacter, weight, density, cellularity, diagonal degree, π-weight, π-character, netweight etc.
This work was supported by Science and Technology Assistance Agency under the contract No. APVT-51-006904. The authors would
like to thank Ľubica Holá for suggestions and comments. 相似文献
955.
Computing semiparametric bounds for option prices is a widely studied pricing technique. In contrast to parametric pricing techniques, such as Monte-Carlo simulations, semiparametric pricing techniques do not require strong assumptions about the underlying asset price distribution. We extend classical results in this area. Specifically, we derive closed-form semiparametric bounds for the payoff of a European call option, given up to third-order moment (i.e., mean, variance, and skewness) information on the underlying asset price. We analyze how these bounds tighten the corresponding bounds, when only second-order moment (i.e., mean and variance) information is provided. We describe applications of these results in the context of option pricing; as well as in other areas such as inventory management, and actuarial science. 相似文献
956.
A modified Langmuir–Hinshelwood model based on intrinsic reactions was proposed. Similar to the Langmuir–Hinshelwood model,
the modified model predicts that both the reciprocal of reaction rate constant 1/k
r
and the adsorption rate constant K
s
are linearly proportional to the reciprocal of the square root of light intensity 1/I
1/2
. The validity of the modified kinetic model was verified with the experimental data of dimethyl phthalate (DMP) degradation. 相似文献
957.
Xinghong Zhang Lin Xu Wenbo Han Ling Weng Jiecai Han Shanyi Du 《Solid State Sciences》2009,11(1):156-161
Hot-pressed zirconium diboride (ZrB2) matrix composites containing 0–30 vol% silicon carbide (SiC) whiskers have been investigated to determine the effect of composition (i.e. amount of SiC whiskers) on the microstructure, mechanical properties and thermal properties. With increasing SiC whisker volume contents, the flexural strength and fracture toughness of the composites were improved compared to those of monolithic ZrB2. Flexural strength increased from 629 MPa for pure ZrB2 to 767 MPa for ZrB2–30 vol%SiCw. Likewise, fracture toughness ranged from 5.4 to 7.1 MPa m1/2 over the same composition range. Specific heat capacity increased with SiC whisker addition, while thermal diffusivity and thermal conductivity decreased slightly with the increase of SiC whisker content. 相似文献
958.
An approach for solving Fredholm integral equations of the first kind is proposed for in a reproducing kernel Hilbert space (RKHS). The interest in this problem is strongly motivated by applications to actual prospecting. In many applications one is puzzled by an ill-posed problem in space C[a,b] or L2[a,b], namely, measurements of the experimental data can result in unbounded errors of solutions of the equation. In this work, the representation of solutions for Fredholm integral equations of the first kind is obtained if there are solutions and the stability of solutions is discussed in RKHS. At the same time, a conclusion is obtained that approximate solutions are also stable with respect to ∞ or L2 in RKHS. A numerical experiment shows that the method given in the work is valid. 相似文献
959.
Rapid solidification processing (cooling rate from the interval 105–106 K s−1) was used to prepare deeply undercooled cryolite-alumina melts. Such prepared samples were analyzed by the XRD method. Besides
cryolite, XRD patterns belonging to ι-Al2O3 were recorded. The influence of annealing on the XRD patterns of deeply undercooled melts was also investigated. 相似文献
960.
In pH 5.5 phosphate buffer solution,N-n-undecyl-N'-(sodium-p-amino-benzenesulfonate)thiourea(UPT)produced a pair of redox peaks on the bare glassy carbon electrode.At the multi-walled carbon nanotube(MWNT)modified electrode,the electrochemical behavior of UPT enhanced greatly.In the presence of bovine serum albumin (BSA),the peak currents of UPT decreased linearly due to the formation of a super-molecular complex.This method was successfully applied to the determination of BSA in a bovine serum sample. 相似文献