Bio-CMP制浆过程中的纤维分离机制(Ⅰ)

在传统化学机械法制浆之前,用木聚糖酶预处理木片获得生物化学机械浆(Bio-CMP).在预处理阶段,木聚糖酶能水解纤维细胞壁上的部分木聚糖,从而引起木片中部分木聚糖的溶出,疏松了木片结构.由于阔叶木纤维细胞壁的初生壁和次生壁S1层具有较高浓度的半纤维素,阔叶木半纤维素的主要组分是木聚糖,因此在后续的盘磨磨浆过程中,纤维之间的分离更多地发生在结构疏松的初生壁P层和次生壁的S1层,而不是传统CMP磨浆过程中的胞间层(ML),使得更多的微细纤维能够暴露在纤维的表面.     

巨菌草纤维特性分析及其木素结构表征

对巨菌草纤维形态、化学成分组成、木素结构及其微区分布进行了研究。利用纤维质量分析仪(FQA)测得纤维平均长度为0.95 mm,宽度为23.1μm,长宽比为41.1。高效液相色谱(HPLC)定量分析碱性硝基苯氧化产物确定巨菌草木素结构为典型的GSH型。利用核磁共振磷谱(31P-NMR)定量分析木素各酚羟基功能基团,结果显示脂肪族羟基含量最高,为3.96 mmol/g,其中非缩合型羟基占总酚羟基的比例较大,为96.3%;二维核磁共振(2D-HSQC NMR)波谱分析表明,β-O-4'芳基醚键结构比例最高,为84.4%;其次为β-β'树脂醇结构和β-5'苯基香豆满结构,所占比例分别为9.9%和5.7%;在芳香区含有大量的紫丁香基和愈创木基结构单元,其中S/G比例为1.25。共聚焦拉曼光谱(CRM)分析表明,木素在细胞不同区域的浓度由大到小的顺序为细胞角隅CC复合胞间层CML次生细胞壁SW;羟基肉桂酸的浓度分布规律与木素的分布变化相似,但其浓度低于木素的浓度。     

~(13)C同位素示踪法研究半纤维素与木素之间的连接方式

为了阐明植物纤维原料中木素与半纤维素之间的相互关系,本文从甘露糖单元的角度分析糖与木素苯丙烷结构单元之间的连接方式。为了使生长中的植物的细胞壁甘露糖单元上的碳原子被碳-13同位素示踪并抑制甘露糖向木素转化,将带D-13C6-甘露糖、外源性木素前驱物松伯醇β-D-葡萄糖苷以及苯丙氨酸解氨酶的抑制剂一起投入到银杏植株中。通过碳-13丰度检测得知银杏中半纤维素被碳-13同位素成功标记,外源性的D-13C6-甘露糖主要在次生壁中发生聚合沉积。FT-IR谱图分析发现投入的外源性糖等没有影响银杏植株的正常生长,高分辨率CP/MAS13C-NMR证实了甘露糖单元的C6位置与木素苯丙烷结构上的α-C存在连接键,主要为醚键。     

离子减薄仪应用于植物纤维超微结构的观察

利用离子减薄仪制备薄膜样品的方法,能较好地满足透射电镜(TEM)对天然纤维细胞壁超微结构的观察.与传统的复型制样方法相比,这种薄膜样品制备方法能够观察到真实的纤维试样,而且制样过程中无毒,制样时间短,得到的信息较多,费用低.光叶楮木质部纤维细胞壁超微结构研究发现,初生壁(P层)和次生壁的S1层很薄,在较低打浆能耗下就被剥离掉,S2层较厚,S3层极薄以致透明,并与纤维细胞腔紧密相连.P层上微细纤维成网状排列,次生壁S1层上的微细纤维与纤维轴的夹角很小,几乎平行.次生壁S2层上的微细纤维与纤维轴的夹角较小,并存在三种排列方式.次生壁S3层上微细纤维成网状排列,与一般造纸用木材和草类原料相似.光叶楮木质部纤维细胞壁的超微结构的特征,是光叶楮杆芯硫酸盐浆比三倍体毛白杨硫酸盐浆易于打浆,浆料的结合强度较好的原因之一.     

柠条正常木与受拉木纤维细胞超微结构及木质素微区分布研究

采用透射电子显微镜（TEM）、扫描电子显微镜-X射线能谱仪（SEM-EDXA）及共聚焦激光扫描显微镜（CLSM）研究了柠条（Caragana korshinskii）正常木与受拉木纤维细胞的超微结构及木质素在细胞壁中的分布。结果表明,柠条正常木纤维细胞壁分为胞间层（ML）、初生壁（P）、次生壁外层（S1）、次生壁中层（S2）、次生壁内层（S3）;而受拉木与正常木不同,其细胞S3层被凝胶层（G层）取代。正常木与受拉木中导管和木射线细胞壁的木质素浓度均比纤维细胞壁的高。正常木纤维细胞各形态区的木质素浓度不同,细胞角隅区的木质素浓度最高,其次是复合胞间层（CML）,S2层最低。柠条受拉木纤维细胞壁中除G层未木质化外,与正常木细胞壁各层木质素分布相似。     

巨菌草的生物结构及制浆造纸性能

对巨菌草的生物结构和化学组分进行分析,并对巨菌草的硫酸盐法制浆性能进行了初步研究。结果显示:巨菌草具有禾本科生物结构的显著特点,含有薄壁细胞、导管和纤维组织带;巨菌草的纤维平均长度为0.91 mm,宽度为21.1μm,长宽比值为43.3,壁腔比为0.8;巨菌草的硝酸-乙醇纤维素含量达39.09%,而酸不溶木素（12.03%）、聚戊糖（22.75%）和灰分（5.9%）含量相对较低,这些特点使其易于蒸煮,化学药品消耗低,制浆得率高,容易打浆,是比较适合制浆造纸的非木材纤维原料;巨菌草的硫酸盐法制浆造纸性能良好,抄片的裂断长为2.73 km,撕裂指数为11.568 m N·m²·g^-1,耐破度为1.846 kPa·m²·g^-1。     

沙柳的超微结构及其木素微区分布的研究

采用光学显微镜(LM)、透射电子显微镜(TEM)、扫描电子显微镜结合X射线能谱仪(SEM-EDXA)及共聚焦激光扫描显微镜法(CLSM)研究了沙柳(Salix psammophila)的超微结构及其木素在各形态区的分布.结果表明,沙柳纤维细胞壁分为初生壁(P)、胞间层(ML)及次生壁(S)层,且细胞角隅胞间层(CCML)、胞间层(CML)、次生壁中层(S2)的木素浓度比为1.96:1.33:1;同时,CLSM图像(530 nm)显示,导管和胞间层中的木素浓度比纤维细胞中的木素浓度高.     

花棒的解剖结构及超微结构研究

采用光学显微镜（LM）、扫描电子显微镜（SEM）及透射电子显微镜（TEM）研究了花棒（hedysarum scoparium）的纤维形态、解剖结构及超微结构.结果表明：花棒主要由导管、木纤维、木射线薄壁细胞及少量轴向薄壁细胞组成.花棒属于阔叶木散孔材,木射线单列同型、导管上的纹孔排列方式为互列式.通过与毛白杨、麦草和红松的形态学参数比较研究发现,花棒虽然属于短纤维,纤维平均长度为0.68mm,但是其纤维形态良好.纤维细胞壁的超微结构典型地分为胞间层（ML）、初生壁（P）、次生壁外层（S1）、次生壁中层（S2）及次生壁内层（S3）.     

竹浆PFI磨浆过程中纤维的形态研究

本论文用扫描电镜和多媒体纤维镜观察竹浆磨浆过程中纤维的变化。结果发现:磨浆前期,竹纤维初生壁(P)和次生壁外层(S1)破裂,纤维细胞壁表面发生了较明显的起毛,纤维被大量的切断。磨浆中期,竹浆纤维以分丝帚化为主,轴向排列的微纤维逐渐从次外层(S2)上剥离下来。磨浆后期,竹浆纤维继续分丝帚化,微纤维继续从细胞壁表面剥离,但是剥离难度变大。     

三倍体毛白杨纤维形态及木素的微区分布

三倍体毛白杨属于杨柳科(Salicaceae)、杨属(Populus)白杨派(Section leuce)树种,它是采用细胞染色现代高新技术,对普通毛白杨的遗传基因进行优化组合,成功培育出来的一种全新的杨木新品种-三倍体毛白杨.三倍体毛白杨耐候性好,适应性强,生长速度快,5年即可成材.一般树高均达到 15m左右,胸径为150～300mm,与10年生长的普通毛白杨生长量相当.三倍体毛白杨选育的成功,不但对生态环境境、森林植被具有重要的经济效益,而且有助于改善我国北方造纸业的纤维原料资源状况.为了进一步了解三倍体毛白杨的纤维形态和制浆性能,本文不同地区种植的三倍体毛白杨木材密度、纤维形态、化学成分等指标进行了详细地分析测定,并对其微纤维走向及木素的微区分布做了深入的研究.研究结果表明三倍体毛白杨木质部由心材及边材两部分组成,其材质较白,白度约为50%左右,而且具有纤维较长、长宽比较大、纤维素含量高和木素含量低的优点,这些优点对制浆造纸都极其有利.纤维形态主要由四种细胞组成,即纤维、导管、木射线细胞及木薄壁细胞.纤维有韧性木纤维和木纤维两种,前者纤维壁上有横节纹,后者没有横节纹而有少量直径很小的纹孔.导管由导管分子组成,导管分子两端开口为单穿孔,并有舌状尾部,细胞壁较薄,壁上有两种类型的纹孔,与导管连接部分的纹孔为具缘纹孔,数量较多,通常分布在导管壁上的某一部位,导管与木射线相连部位的纹孔为单纹孔,孔径较大,数量少,通常一组一组的横向排列;木射线细胞及木薄壁细胞二者都沿径向排列,木射线细胞有少部分边缘有细小的齿状,木薄壁细胞体积短小,壁上有纹孔.从木材横切面上测量各种细胞所占的面积百分比,近似于树干中各种细胞的体积百分比,其结果约为纤维细胞占70%,导管占20%,木射线细胞以及木薄壁细胞占10%.三倍体毛白杨纤维细胞壁是由胞间层(ML)、初生壁(P)及次生壁外层、中层、内层(S1、S2、S3)组成.其微纤维的走向,P层为网状结构.S1层为交叉螺旋形,与纤维轴的交角约为80°左右.S2层为平行螺旋状,与纤维轴的交角为30～45°.在打浆过程中,初生壁及次生壁外层容易成片状剥落,但S2层由于微纤维角度较大,不容易分丝帚化.S2层是细胞壁的主要组成部分,约占整个壁层体积的70%.根据高锰酸钾对木素有比较专一的反应性能,采用扫描电子显微镜与X-射线能谱仪(SEM/EDXA)技术研究三倍体毛白杨木素的微区分布.结果表明三倍体毛白杨纤维细胞、导管分子、木薄壁细胞及木射线细胞各形态区,木素密度都是细胞角隅区(CC)最高,胞间层(CL)次之,S2层密度小.这与一般木材的木素微区分布规律是相符的.以S2层的木素密度为1,分别计算出细胞角隅区、胞间层和S2层木素的密度比为CCCLS2=1.71.31左右.结合纤维细胞壁的观察结果,纤维细胞次生壁S2层的厚度占了细胞壁总厚度的近80%,故S2层的木素浓度虽然较低,其含量在纤维细胞中仍然是最大的.研究中还发现三倍体毛白杨胞间层的木素比较容易软化,软化后的细胞壁受到外力作用时容易在S1层与S2层之间分离.能在纤维表面暴露出较多的S2层结构,使纤维表面具有较多的羟基,在纸页抄造时便产生较多的氢键结合,从而赋予纸页较好的纤维结合强度.近年来许多造纸工业比较发达的国家,在发展杨木速生林CTMP浆时取得了较好的经济效益,这和杨木属的超微结构与局部化学上的这特点有密切关系.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

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 Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.