纸浆硬度──海波值的测定

纸浆硬度是蒸煮后浆中残留下来的非纤维素物质（即水质素）含量的多少，亦即脱去木质素的程度。它与漂白时需用的漂白剂量有关。测定该硬度的方法有多种，从原理上说都不外乎是用氯、次氨酸盐、高锰酸钾等作为氧化剂，对木素发生作用后再间接换算求出。目前，我国常用的测定项目主要有卡伯值（GB1546—89）、高锰酸钾值（GB1547－89）。过去使用的贝克曼价、劳民值等均已弃用。在70年代中期，北美等国推荐以所谓的海波值（HypoNumberofPulp）正式确定为纸浆硬度的测定法。可惜，那时候我们对此一无所知。80年代初，由轻工业出版社出版的…     

大液比药液循环蒸煮对蔗渣烧碱法制浆的影响

本实验以蔗渣为原料,采用烧碱法蒸煮制浆,研究了大液比药液循环蒸煮中用碱量的影响,并讨论了加大液比对蔗渣制浆性能的影响。结果表明,与传统烧碱-蒽醌法蒸煮工艺相比,大液比药液循环蒸煮的碱耗略高,但处于合理范围,并且能够深度脱除木质素,获得纸浆卡伯值较低（8.9~13.5）、黏度较高（973~1134 mL/g）,有利于提高纸浆的滤水性能。同时,大液比药液循环蒸煮后,蔗渣浆纤维形态的主要分布同桉木浆一致,数均纤维平均长度约1.00 mm,数均纤维平均宽度约26.0 μm。     

可见光光谱技术在亚硫酸盐浆卡伯值在线测量中的应用

卡伯值是纸浆质量的重要指标,而纸浆中的木素含量决定了纸浆的卡伯值。本研究是用可见光分光光谱技术在线测量酸法制浆过程蒸煮液中木素的浓度,通过蒸煮液中溶出的木素含量去推算纸浆中木素含量和纸浆的卡伯值。本文确定了合适的可见光光谱测量波段,并建立了纸浆卡伯值与蒸煮液吸光度之间的数学模型,为实现蒸煮过程卡伯值的在线测量提供了依据。     

高锰酸钾值

常琦同志:你提出的高锰酸钾值有关问题,现简要答复如下,仅供参考。(姜晓角)高锰酸钾值是测定纸浆硬度的方法之一,俗称锰价。纸浆硬度有许多测定方法,利用高锰酸钾测定的还有:卡伯值、贝克曼价;利用氯来测定的有:劳氏法;利用次氯酸盐溶液来测定的有齐白价,恩苏法、氯价法等,均不在本文讨论之列。     

纸浆纯化处理工艺对超高压绝缘纸性能的影响

本研究以硫酸盐云杉浆为原料,探讨了碳酸氢镁和醋酸镁对纸浆纯化处理效果的差异。采用冷碱抽提、过氧化氢漂白工艺对纸浆进行纯化,并对纸浆的化学组分和纸张电气性能进行分析。结果表明,相比醋酸镁,碳酸氢镁对Na+的置换作用更强,对纸浆化学性能的提升更为显著。碳酸氢镁处理能够使纸浆水抽提液pH值和电导率满足500 kV超高压变压器匝间绝缘纸的指标要求。冷碱抽提和过氧化氢漂白均可有效去除木质素,提高纸浆α-纤维素含量,有效降低纸张的介质损耗。其中,冷碱抽提对纸张电气性能的提升效果更显著,可降低纸张在全频段的相对介电常数,并使浸油后的绝缘纸在工频下的tanδ值降低61.6%。     

卡伯值测定方法与非木纤维纸浆的适配性研究

正本刊讯(SFT消息)近日,美国SFT纤维技术公司进行一项研究,在研究人员Sabrina Burkhardt组织下,研究了非木纤维纸浆内的木质素测定方法。一直以来,木浆仍占据制浆造纸行业的主流,卡伯值测定方法比传统Klason法的测定速度更快、效率更高,是测定纸浆内木质素脱除度的有效手段,通过强氧化剂与木质素和有机官能团的化     

可见光光谱技术在亚硫酸盐浆卡伯值在线测量中的应用

卡伯值是纸浆质量的重要指标,而红浆中的木素含量决定了纸浆的卡伯值。本研究是用可见分光光谱技术在线测量酸法制浆过程蒸煮液中木素的浓度,通过蒸煮液中溶出的木素含量去推算纸浆中木素含量和纸浆的卡伯值。本文确定了合适的可见分光光谱测量波段,并建立了纸浆卡伯值与蒸煮液吸光度之间的数学模型,为实现蒸煮过程卡伯值的在线测量提供了依据。     

H_2O_2漂白杨木APMP纸浆特性的研究

经过化学机械法处理的杨木APMP高得率浆保留了大量的木质素,因此初始白度不高,并且白度稳定性差。过氧化氢是一种保留木质素型的温和漂白剂,对木质素的发色基团有一定的抑制作用。本文研究探讨了不同p H值、不同漂白时间、不同的H2O2添加方式、活化剂用量等因素对杨木APMP纸浆漂白效果的综合影响。研究结果表明:分段加入H2O2漂剂,补充添加漂白剂都有利于提高纸浆的白度,提高漂白剂的漂白效率。     

液比对速生桉木硫酸盐制浆效果的影响

以我国速生桉木为原料,研究液比对其硫酸盐法制浆效果(卡伯值、残碱、黏度、粗浆和粗渣率、纸浆纤维分布均一性)的影响。结果表明:增大液比使蒸煮液的碱浓度降低,蒸煮效率下降;而纸浆的粗浆得率、黏度、纤维的平均长度与卡伯值之间的关系几乎不受液比的影响;另外,随着蒸煮液比的增大,相同卡伯值下的纸浆粗渣率下降,纤维长度分布均一性升高,分界点的液比为4.5。因此,从减少粗渣率以及提高纸浆纤维分布均匀性的角度来看,适宜的蒸煮液比应为4.5。     

氧漂桉木硫酸盐浆臭氧漂白工艺研究

采用硫酸盐法制备桉木硫酸盐浆,经氧脱木质素处理后,对其进行臭氧漂白工艺的研究。探究臭氧漂白过程中浆浓、漂白时间、pH值、臭氧用量等对纸浆漂白性能及成纸性能的影响,得到较优的漂白工艺条件。结果表明,当浆浓为35%、漂白时间3 min、臭氧用量0.9%和pH值为2.0时,所得纸浆白度为76.9%ISO、纸浆黏度为535 mL/g、纸浆Kappa值为2.71,成纸抗张指数、耐破指数、撕裂指数和耐折度分别为57.4 N·m/g、4.77 kPa·m²/g、7.95 mN·m²/g和89次。     

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