一种基于余弦函数的普适性双原子分子解析势能函数

提出了一种构造解析势能函数的新方法,得到了一种既适用于中性双原子分子又适用于带电双原子分子离子的解析势能函数.用8种基本类型的双原子分子,即同核中性基态双原子分子H2-X1∑+g,同核中性激发态双原子分子C2-d1∑+u,同核带电基态双原子分子离子O+2-X2∏g,同核带电激发态双原子分子离子N+2-B2∑+u,异核中性基态双原子分子PuO-X1∑+g,异核中性激发态双原子分子PbS-A1∑+,异核带电基态双原子分子离子(BC)--X3∏,异核带电激发态双原子分子离子CS+-A2∏共25个算例对势能函数进行了验证,并与RKR(Rydberg-Klein-Rees)等实验数据进行了比较,计算结果与RKR数据相符性好.     

基态H_2S~+的几何结构与势能函数的研究

从量子力学出发,使用密度泛函理论B3LYP,B3P86方法和二次组态相关QCISD方法,在多种基组水平下,对H2,HS+和H2S+的结构进行优化,得到了其平衡几何构型、谐振频率和二阶力常数.采用最小二乘法拟合出H2,HS+基态分子离子的解析势能函数,并运用多体项展式理论推导出了基态H2S+离子的解析势能函数,势能面正确反映了其平衡构型特征.     

氢分子离子H+2键长和离解能的一种解析计算法

利用一种具有相位因子和斥力项的势函数，给出了氢分子离子H2^ 的键长和离解能的解析计算式．在特定相位条件下，由此计算出的键长和离解能与实际值相吻合．     

计算中高能区电子与多原子分子散射总截面的经验公式

根据相关文献中实验测得的一些分子总截面与分子极化率的定量关系,利用分子的平均键长和极化率等参数拟合了一种计算中高能区电子与多原子分子散射总截面的经验公式,并对e-CH3Cl,e-CH2Cl2,e-CH3I和e-O3散射的总截面进行了计算,结果与文献中的实验结果较为吻合.     

J/ψ粒子夸克势的解析计算

利用一种带相位因子的场方程,给出了J/ψ粒子夸克势的解析表达式,并与文献中给出的KMS和erf两种夸克势作了比较.     

研究速递

欧洲科学家利用激光驱动电子运动绘制原子全息图由荷兰、德国和法国等多国科研人员组成的研究团队,通过激光驱动电子运动绘制了原子全息图。在实验中,研究人员向一个原子或分子发射一束致密的红外激光,使原子或分子电离释放出电子,激光场驱动自由电子在离子周围做往复振荡运动,如果电子与离子相撞,就能在极短时间内发出辐射能量。研究人员认为,由于电子运动完全相干,其总是处于     

关于SmarandacheCeil函数的一类均值问题

研究了SmarandacheCeil函数与素因子积函数U（咒）的均方值的分布问题．利用解析方法给出了（Sa（n）-U（n））2。的一个有趣的渐近公式，其中k≥2，以为自然数．     

基于量子拍的分子离解的研究

为了研究Rb2分子离解的超快过程,分析了铷原子中两个耦合的参量四波混频过程,研究了量子拍随时间的演化.实验上利用泵浦-探测方法得到铷原子中参量四波混频信号随脉冲延迟的变化.结果表明,当2个耦合的参量四波混频过程的相位匹配达到平衡时,参量四波混频信号中可以观察到量子拍,量子拍幅度随时间的变化反映了由光聚合产生的分子的离解对激发的原子波包的影响.对参量四波混频时域信号进行含时傅立叶变换,得到了量子拍随时间的演化,从而提供了探测分子离解超快过程的方法,并进一步计算出了Rb2分子离解的时间.     

基于密度泛函研究锌的卤化物的分子结构及振动频率

采用密度泛函理论中的12种泛函，结合高级别的基函数aug‐ccpvqz（‐pp），系统研究ZnF2、ZnCl2、ZnBr2和ZnI2分子的结构和振动频率，并与实验结果进行对比。一方面，得出了这4个分子的结构和振动频率的高精度的理论结果；另一方面，将这12种泛函的计算结果与实验结果作对比，评估这12种泛函对研究这4个分子的结构和性质的适用性。结果显示，PBE和BPW91泛函更适用于计算ZnF2分子；X3LYP ，PBE ，BPW91和BP86泛函更适用于计算 ZnCl2分子；PBE0泛函更适用于计算ZnBr2分子；M06和PBE0泛函更适用于计算ZnI2分子。     

Smarandache LCM的对偶函数与最小素因子函数的均方值

研究了Smarandache LCM函数的对偶函数与最小素因子函数的均方值分布问题.利用初等及解析方法给出一个有趣的均值公式,从而推出这两个函数的值几乎处处相同.     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the