一类二阶常微分方程泛函边值问题解的存在性

运用打靶法考虑了二阶常微分方程泛函边值问题{x″（t）=f（t,x（t）,x′（t））,t∈[0,1],x（0）=0,x（1）=∫0^1α（t）x（t）dt解的存在性,给出了此类问题解的存在性判据,其中f：[0,1]×R^2→R满足Carathéodory条件,α∈C（[0,1],[0,∞））,且∫0^1α（t）tdt〈1.     

利用NMR技术研究淀粉的结构和性质

介绍了国外利用^1H-NMR和^13C-NMR谱中^1H和^13C的化学位移变化分析淀粉、变性淀粉及其水解产物的分支程度、变性淀粉的取代度和取代位，利用高分辨率固相NMR技术分析淀粉粒的内部结构；阐明了利用^1H－NMR、^2H－NMR及^17O－NMR谱的T1、T2等参数可以分析淀粉中自由水、结合水的含量，研究水的分布和动力学特点；举例说明了在液相和固相共存的淀粉体系中利用低分辨率的^1H－NMR以入^13C CP／MAS技术分析测定淀粉的老化性质。^^     

新型可调式桥板的设计探讨

在工程测量及机械加工行业的平面度检验中,一般采用合像水平仪或自准直仪检验平面度。尤其在检验大平面时,桥板是必不可少,非常重要的辅助检验工具。但目前使用的桥板受其长度规格的限制。为使测点构成封闭四边形(图1),必须准备三块长度不同的桥板,且与被测面的纵、横、对角线长度成等比关系。设被测面纵、横、对角线长度分别为a、b、c,桥板长度分别为a′、b′、c′,应满足:a:b:c=a′:b′:c′正方形平面需准备两块桥板。否则,就会使平面度的检验不能包容整个平面,而只能检验平面的一部分,甚至不能得到理想的测量数据,完不     

枫浆乳化糊的流变特性

作者通过流变学测试证明了枫浆乳化糊流变行为符合关系式τ=Kγ,主要表现出假塑性。在恒定切变速率下,其表观粘度η与乳化糊浓度C的关系符合方程式Lgη=Lgη_0 KC,我们也可以用η=exp(A′ B′/T)~2来描述表观粘度η与流变体系温度T的关系,进而说明了枫浆乳化糊有被开发用于染整糊料的可能性。     

天然山楂香料挥发性组分的结构表征及其保留时间的估计和预测

用分予电距矢量（MEDV）对天然LU楂香料挥发油的51种组分在Ultra2柱上气相色谱保留时间（tR）进行了定量构效关系的研究。通过多元线性回归,得到的模型相关系数R=0．977。用逐步回归的方法筛选5个变量进行建模,相关系数R=0．950,再用留一法（1eave-one-out,LOO）交互检验对模型进行评价,得到的相关系数Rcv=0．924。所以此模型具有较好的稳定性和预测能力。     

凝固型含醇发酵乳的研制

以米酒的制作工艺为基础，采用分步发酵和混合发酵两种工艺对含醇发酵乳制作进行探讨，筛选具有最佳风味产品的工艺参数。结果表明：采用分步发酵较好，其工艺参数为：酒酿用量为16％，乳酸菌为3％，加糖量为7％发酵温度为42℃，时间为3h。产品中固形物含量为12％，乙醇量达0．33％，酸度高于75^0T，粘度达490cP.     

二氧化氯缓释剂对低温贮藏荔枝品质及关键花青素的影响

荔枝采后易由花青素降解、呼吸代谢等导致其品质劣变,而二氧化氯（ClO2）有护色和抑制呼吸的多重作用。为探明ClO2对采后荔枝的综合影响,本研究分别采用0.1 g(T1)、0.4 g(T2)和1.2 g(T3)ClO2缓释剂处理荔枝,以0 g(CK)为对照,通过品质指标、色泽指标、花青素等评价其保鲜效果,并通过相关性分析探讨它们间的联系。结果表明,T1组荔枝贮藏品质最佳。贮藏7 d时,T1组荔枝可溶性固形物、a*值分别比同期CK组显著（P<0.05）提高了2.93%和10.13%,而呼吸速率显著（P<0.05）降低了34.54%。与此相反,T3组荔枝第7 d相对电导率达最高值35.84%,a*达降到最低值18.38,说明细胞结构破坏、漂白明显,贮藏品质最差。为进一步探明色泽变化与花青素的关系,筛选出荔枝中10种关键花青素,含7种原花青素,它们占总花青素达66.96%。相关性分析表明,在贮藏期内,T1、T2、T3组中色泽a*值与矢车菊素半乳糖苷的相关系数分别为0.980、0.548、0.360,与矢车菊素-3-O-葡萄糖苷的相关系数为0.985、0.488、0.402。T1组维...     

含酸奶饲料对衰老小鼠某些免疫功能指标的影响

用含Lactobacillus bulgaricus和Streptococcus Thermophilus活菌酸奶30％的饲料饲喂衰老小鼠3d，测定其胸腺重量、脾淋巴细胞增殖能力、IL-2（Interleukin，IL）产生量、脾T淋巴细胞中CD4^＋／CD8^＋细胞比例等指标，发现饲喂酸奶显著增加了胸腺重和IL-2的产生量,提高了脾T淋巴细胞的增殖能力，但未达到年轻小鼠的水平。此外还观察到酸奶处理提高了T淋巴细胞中CD4^＋／CD8^＋细胞的比例。这些结果表明，酸奶对于老年小鼠的免疫功能具有一定恢复作用。     

Banach代数上映射的方向导数

设A为一有单位元的复Banach代数，D包含A为非空开集。西方中引入并研究了映射F：D→A的一阶方向导数DF（a）和高阶方向导数D^(n)f(a)。利用Riesz函数演算，证明了它们的一些性质，讨论了它们与内导子δa的关系。特别地，当f∈H（Ω），a∈A且δ(a)包含Ω时，得到了算子δ^(n)F(a)的一个表示。     

环锭纺气圈稳定条件的研究

提出了环锭纺气圈的稳定条件，此条件限定导纱钩处纱线张力在一定范围之内，其临界值为T0min和T0max。经计算，气圈高度增大，T0min和T0max近乎呈线性增大，幅度变宽。设计时可取T0接近T0min。     

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