反相微乳液制备两性聚丙烯酰胺的工艺优化

通过电导率和透光率来优化反相微乳液制备两性聚丙烯酰胺的合成工艺,得到最佳合成条件为:EDTA加入量0.5%(对单体质量)、搅拌速度为300 r/min、乳化剂用量为18.61%(对乳液总质量)、反应时间为3 h、引发剂用量为0.5%(对单体质量)、单体质量分数为50%(对水相质量)、反应温度为25℃;并检测了在此优化条件下制备的两性聚丙烯酰胺的助留助滤性能,结果表明,该两性聚丙烯酰胺具有较好的助留助滤性能,当加入量为0.08%(对绝干浆)时,纸料留着率提高了8.9%,打浆度降低了6.1°SR。     

阳离子聚丙烯酰胺/膨润土体系的助留助滤性能

采用水溶液自由基聚合制备了非离子型聚丙烯酰胺,再经过Hofmann降解法得到阳离子聚丙烯酰胺。然后用正交实验对Hydrocol体系的助留助滤性能进行了研究。实验表明,Hydrocol体系最佳配方为阳离子聚丙烯酰胺的加入量0.08%、分子量403万,膨润土用量0.4%,灰分含量最大可提高0.79%,打浆度最大可降低5.13°SR,表明自制阳离子聚丙烯酰胺与膨润土构成的Hydrocol体系具有较理想的助留助滤性能。     

阳离子聚丙烯酰胺的Hofmann法制备及其助留助滤性能

采用水溶液自由基聚合制备了非离子型聚丙烯酰胺,再经过Hofmann降解法得到阳离子聚丙烯酰胺。然后用正交实验对Hydrocol体系的助留助滤性能进行了研究,实验表明,Hydrocol体系最佳配方为阳离子聚丙烯酰胺的加入量为0.08%、分子量为403万,膨润土用量为0.4%,灰分量最大可提高0.79%,打浆度最大可降低5.13SR,表明由自制阳离子聚丙烯酰胺与膨润土构成的Hydrocol体系具有较理想的助留助滤性能。     

新型结构两性聚丙烯酰胺增强、助留助滤性能的研究

研究了新型结构两性聚丙烯酰胺的增强、助留助滤作用。结果表明，其对各种废纸浆及非木材纸浆均具有良好的增强、助留助滤效果外，不仅能与硫酸铝复配使用，更适合中性抄纸的要求。两性聚丙烯酰胺除了具有良好的增强、助留助滤效果，还具有很好的辅助施胶效果，用量为O．2％时，可使纸浆施胶度提高50％以上。     

两性高分子聚丙烯酰胺助留助滤剂在非木材纤维中的应用效果

在非木材草类纤维中加入两性高分子聚丙烯酰胺助留、助滤剂，对其效果进行了探索。实验结果表明：用量在1％时，其助滤、助留的效果最好。但高分子的聚丙烯酰胺的助滤效果远不及助留效果好。     

矿物纤维二元助留助滤体系的构建及性能研究

该文以矿物纤维、阳离子聚丙烯酰胺（CPAM）和阴离子聚丙烯酰胺（APAM）为主要原料分别构建CPAM/矿物纤维及APAM/矿物纤维二元助留助滤体系,对造纸湿部助留助滤性能、纸浆流变行为及成纸抄造性能进行了探讨.结果表明,CPAM/矿物纤维二元复配体系具有较佳助留助滤效果,且当矿物纤维的用量为0.2％质量分数（下同）时最为合适.     

反相微乳液制备两性聚丙烯酰胺的正交实验优化

通过正交实验分别探讨了反应温度、引发剂用量、反应时间和单体浓度对两性聚丙烯酰胺(PDAA)的相对分子质量、转化率和乳液稳定性及其对纸料的助留助滤性能的影响。通过比较产品质量和对纸料的助留助滤性能,得到了制备PDAA的最佳条件为:EDTA加入量为0.5%(基于单体质量)、充氮时间为20 min、搅拌速度为300 r/min、乳化剂用量为18%(基于单体质量)、引发剂用量为0.4%(基于单体质量)、单体浓度为54%(基于水相)、反应温度为24℃和反应时间为3 h。并采用红外光谱和紫外光谱对PDAA结构进行了表征,结果说明,通过反相微乳液制备PDAA获得成功。     

新型CPAM的合成及CPAM／膨润土体系的助留助滤性能

以自制阳离子单体、丙烯酰胺为聚合单体,采用共聚法合成出新型阳离子聚丙烯酰胺(CPAM)。采用正交实验对合成影响因素和CPAM/膨润土微粒助留系统的助留助滤性能进行了探讨。实验结果表明,当引发剂质量分数为0.05%,n(丙烯酰胺)∶n(阳离子单体)=8∶1、反应温度55℃时,CPAM/膨润土具有较好的助留助滤效果。     

季铵型两性聚丙烯酰胺的合成及应用

采用反相微乳液法合成了季铵型两性聚丙烯酰胺,检测了制备的两性聚丙烯酰胺的助留助滤及增强性能。实验结果表明,当加入量为0.5%时,纸张的抗张指数提高了11.37%,撕裂指数提高了18.52%,填料留着率提高了7.66%,打浆度下降了12.9%,此时助留、助滤及增强效果最好。     

不同CPAM体系对高得率浆助留助滤性能的影响

考察了自制W／O型和w／w型阳离子聚丙烯酰胺（cPAM）／膨润土体系对高得率浆滤水和留着性能的影响。同时,探讨了高阳电荷密度聚合物改性聚乙烯亚胺（PEI）作为阴离子垃圾捕捉剂,对高得率浆CPAM／膨润土体系助留助滤性能的影响。结果表明,具有较高电荷密度的W／O型CPAM单元体系对高得率浆的助留助滤效果较好;但其与膨润土组成的微粒体系与单元体系相比,进一步提高纸料滤水和留着效果不明显。PEI可以显著改善CPAM或CPAM／膨润土体系对高得率浆的助留助滤性能。PEI与W／O型CPAM（／膨润土）组成的体系对纸料的助留助滤效果较好。当PEI用量为0．02％和CPAM用量为0．03％时,PEI／W／O型CPAM使纸料的滤水速度和总留着率比PEI／W／W型CPAM分别提高了9．5％和1．9％。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press