含硫改性壳聚糖/NCC复合气凝胶的制备及其在废水中应用

本文以纳米结晶纤维素(NCC)和含硫改性壳聚糖为原料,合成含硫改性壳聚糖气凝胶和含硫改性壳聚糖/NCC复合气凝胶。通过扫描电镜(SEM)和比表面积(BET)对两种气凝胶的形貌和结构进行了分析;并通过改变溶液的pH值、初始浓度、吸附时间和吸附剂用量等吸附条件,探究了气凝胶对Hg~(2+)的吸附情况。实验结果表明,与含硫改性壳聚糖气凝胶相比,复合气凝胶的比表面积增大了10.37%;在pH为5、吸附剂用量30.0 mg和Hg~(2+)溶液初始浓度为100mg/L时,复合气凝胶的最大吸附容量达到最大为242.3 mg/g,比含硫改性壳聚糖气凝胶增加了2.02%;并且复合气凝胶对Hg~(2+)的吸附过程符合准二级动力学模型,同时复合气凝胶能用脱附剂EDTA脱附再生。     

纤维素纳米纤维/纳米蒙脱土复合气凝胶制备及其结构与性能

针对纤维素纳米纤维(CNF)气凝胶易燃、强力低等问题,利用纳米蒙脱土(MMT)共混改性纤维素纳米纤维,基于冷冻干燥的方法制备阻燃隔热的CNF/MMT复合气凝胶。研究了MMT质量分数对CNF/MMT复合气凝胶形貌结构、压缩性能、热稳定性、热导率和阻燃性能的影响。结果表明:MMT的引入使气凝胶具有更加紧密的片层结构,气凝胶力学性能、热稳定性和阻燃性能得到改善;在MMT质量分数为50%时,CNF/MMT复合气凝胶的表观密度最大且仅为0.016 8 g/cm³,应变为10%的应力最大为12.45 kPa,应变为70%的应力最大为77.93 kPa,导热系数最大为 0.04 W/(m·K); 气凝胶中MMT质量分数不低于42.9%时,复合基气凝胶的极限氧指数得到明显提升。     

疏水亲油型纳米纤维素气凝胶的制备与吸油性能研究

本研究以不同方法制备的针叶木纳米纤维素（CNF、ECNF和TCNF）为原料,通过冷冻干燥法制备纳米纤维素气凝胶,并利用硬脂酰氯（SAC）溶液浸渍法对其进行疏水改性。采用激光粒度仪、X射线衍射分析仪、Zeta电位仪测定了纳米纤维素的粒径分布、结晶度及电荷密度,并对疏水改性前后气凝胶的密度、孔隙率、结构形貌、疏水性能及吸油性能进行了分析和研究。结果表明,TCNF粒径及电荷分布较为均匀;SAC改性不会影响纳米纤维素气凝胶轻质、多孔的特性,改性后的气凝胶表现出优异的疏水性和良好的吸油性,其中S-ECNFA的疏水性最佳,表面水接触角（CA）可达151.6°;S-TCNFA对4种不同密度的油吸附能力最强,其中对食用油的吸油量可达48.96 g/g气凝胶,经5次循环使用后,对食用油的吸油量仍可达初次吸油量的60.8%,具有较好的循环使用性能。     

疏水改性乳清分离蛋白-普鲁兰多糖复合气凝胶的制备及性能研究

目的:对易吸湿的蛋白/多糖类气凝胶进行疏水改性并对其性能进行评估。方法:对乳清分离蛋（whey protein isolate,WPI）-普鲁兰多糖（pullulan,PUL）复合气凝胶进行低温等离子体处理,使其羟基充分暴露后,使用硅烷偶联剂进行表面接枝处理,获得具有疏水性能的复合气凝胶,并研究其吸湿性、疏水疏油性、抗压性能、热失重、精油装载与缓释性能等。结果:甲基三甲氧基硅烷（methyltrimethoxysilane,MTMS）改性后复合气凝胶的平衡吸湿率为（9.67%±0.323%）,十八烷基三甲氧基硅烷（octadecyltrimethoxysilane,OTMS）改性后复合气凝胶平衡吸湿率为（9.34%±0.276%）,相比为改性前（11.41%±0.506%）均明显降低;改性前,复合气凝胶水接触角为（40.14°±2.16°）,油接触角为（28.07°±2.43°）;MTMS改性后水接触角为（82.10°±4.78°）,油接触角为（56.14°±3.25°）;OTMS改性后水接触角为（85.21°±4.61°）,油接触角为（74.63°±3.08°）;改性后疏水疏油性均有所提升,且OTMS改性处理效果更好。改性前复合气凝胶压缩模量（21.745±1.982）MPa,MTMS改性后（17.655±3.034）MPa,OTMS改性后（18.412±3.513）MPa。改性后抗压强度略有降低,但不影响正常使用。改性前复合气凝胶丁香精油的最大装载率为（254.26%±5.585%）,MTMS疏水改性后丁香精油最大装载率（241.57%±5.214%）,OTMS组则为（223.31%±4.436%）。丁香精油装载率有所下降但缓释性能均有所提升,且MTMS改性缓释效果更好。热稳定性方面均有所提升,且OTMS组热稳定性更好。结论:综上所述,硅烷接枝疏水改性处理可以显著提升复合气凝胶的疏水性并提高其亲油性。适用于油脂类活性物质的装载与缓释应用,拓宽了WPI-PUL复合气凝胶的应用领域。     

海藻酸钠/改性氧化石墨烯复合气凝胶的制备及吸附性能研究

文章利用β-环糊精接枝改性氧化石墨烯,采用原位交联和冷冻干燥技术制备了海藻酸钠/β-环糊精改性氧化石墨烯(SA/GO-β-CD)复合气凝胶,以Cu~(2+)、Cd~(2+)为代表性重金属离子,研究了所制备的复合气凝胶对水体中重金属离子的吸附性能。探讨了不同GO-β-CD浓度制备的复合气凝胶的吸附性能和力学性能,以及不同初始离子浓度下气凝胶对重金属离子的吸附性能。结果表明,随着GO-β-CD浓度的增加,气凝胶的机械强度及弹性均有增大,对重金属离子的吸附容量随着改性氧化石墨烯浓度的增加先升高再逐渐降低。SA/GO-β-CD复合气凝胶对Cu~(2+)和Cd~(2+)的最大吸附容量分别为134.67和160.66 mg/g。     

杉木/纳米Al_2O_3复合改性研究

由于木材(尤其是人工速生林材)的自身缺陷,对木材进行改性已是必然趋势。首先对纳米材料及其在木材科学上的应用作了简要的叙述,其次说明了用无机纳米粒子对木材进行改性的理论依据,最后构想了杉木/纳米Al 2O3复合可能出现的使杉木耐磨性能得到质的提高的预期结果。     

SiO2气凝胶-无纺布或毡纳米复合材料的吸苯性能

具有纳米多孔网络结构的SiO2气凝胶与透气性优良的无纺布或毡进行复合,可得到具有高吸附性能的纳米复合材料,其饱和吸苯率达到并超过了传统的吸附材料。纳米复合材料的饱和吸苯率与单位面积所复合的SiO2气凝胶量和其本身的饱和吸苯率成正比关系,复合工艺对气凝胶孔结构的影响很小,符合一定的理论推导公式。     

改性纳米TiO_2/丙烯酸酯复合乳液的制备及研究

利用溶胶-凝胶法制备了纳米TiO_2溶胶,接着用硅烷偶联剂KH-570对其进行表面改性,降低纳米TiO_2的团聚效应,制备出可与丙烯酸酯单体聚合的改性纳米TiO_2溶胶。然后以过硫酸钾为引发剂,在一定温度下,采用核壳乳液聚合法,制备出改性纳米TiO_2/丙烯酸酯复合乳液。研究了盐酸、硅烷偶联剂的用量对纳米TiO_2溶胶粒径的影响,以及乳化剂、引发剂与改性纳米TiO_2溶胶用量对复合乳液粒径及凝胶率的影响。采用红外光谱、X射线衍射仪、透射式电子显微镜等测试手段对制备的复合乳液进行表征。结果表明:通过该方法成功制备出纳米TiO_2/丙烯酸酯复合乳液,且当引发剂、乳化剂和改性TiO_2溶胶的用量分别占单体总质量的0.5%、4%、1.5%时乳液性能最好。     

木材防水技术又有新突破

北京林业大学材料科学与技术学院木材保护与改性研究团队在引进“纳米乳化型木材防水剂制备技术”的基础上,结合高温热处理材自身的特点,制备了适用于与高温热处理复合改性的纳米级石蜡乳液,其平均粒径在250nm以下,在术材中的渗透性良好,     

纳米ZnO改性巴西樱桃木的抗光老化性能研究

本文以巴西樱桃木(Brazilian cerasis)为研究对象,采用两步法在样品表面原位生成纳米Zn O薄膜。笔者通过对改性前后木材表面微观结构、元素分布、红外光谱、晶体晶型等测试,分析了纳米Zn O改性对基材的影响,并采用人工加速光老化试验评价了纳米Zn O对巴西樱桃木抗光老化性能的影响。结果表明:溶胶-凝胶法在木材表面形成的Zn O薄膜,对材料外观无明显负面影响,且经过人工加速光老化处理,纳米Zn O改性木材的色度学参数值较对照样本变化幅度小。     

Bovine claw and limb disorders related to reproductive performance and production diseases

As part of a cross-sectional study of Norwegian Red Cattle, associations of lameness, lesions at the tarsus, claw shapes, and claw lesions with reproductive performance and production diseases were examined. Fifty-five tiestall herds and 57 freestall herds were sampled by computerized systematic selection and 2,665 cows were trimmed and limb and claw disorders recorded by 13 specifically trained claw trimmers during the late winter and spring of 2002. After exclusions, 2,583 cows were included in this study. Most claw lesions were mild (score 1). Prevalence of moderate and severe lesions (score 2 + 3) did not exceed 5% for any of the lesions. Hazard ratios for independent variables were identified using Cox regression analyses incorporating herd as a random effect in a positive stable frailty model. Wounds and swellings at the tarsus were associated with more clinical mastitis [hazard ratio (HR) = 4.0] and teat injuries (HR = 2.5). Moderate and severe heel-horn erosions in first-lactation cows were associated with increased calving interval (HR = 0.60). Moderate and severe hemorrhages of the sole in first-lactation cows were associated with decreased interval from calving to first service (HR = 1.6) and moderate and severe hemorrhages of the sole were associated with more milk fever (HR = 8.6). All hemorrhages of the sole (scores = 1, 2, and 3) were associated with more reproductive hormonal treatments (HR = 2.3). All sole ulcers in first-lactation cows were associated with longer interval from calving to last service (HR = 0.59) and longer calving interval (HR = 0.61), whereas sole ulcers in older cows were associated with longer calving interval (HR = 0.62). All sole ulcers also were associated with more milk fever (HR = 4.8) in all cows. Moderate and severe sole ulcers in older cows were associated with increased interval from calving to first (HR = 0.35) and last (HR = 0.37) service. Moderate and severe white-line fissures in older cows were associated with increased return rate from previous insemination (HR = 2.4). Our study shows that claw disorders are associated with poorer reproductive performance and some production diseases.     

面絮粒度分布对面条品质影响研究

以13种小麦为原料,将面絮按粒度分级,对不同粒度的面絮分布与籽粒、小麦粉、面条品质进行相关性分析,探索采用面絮评价小麦粉制作面条品质的适应性。结果表明,小颗粒面絮(d1.5 mm)含量与籽粒水分呈显著或极显著负相关,大颗粒面絮(d1.5 mm)含量与其呈显著或极显著正相关;小颗粒面絮含量与面筋指数呈显著正相关,大颗粒面絮含量与其呈显著负相关;小颗粒面絮含量与面条质构参数呈显著或极显著正相关,大颗粒面絮含量与其呈显著或极显著负相关;小颗粒面絮含量与面条感官评价得分呈显著或极显著正相关,大颗粒面絮含量与其呈极显著负相关。综合结果表明:采用面絮评价小麦粉制作面条品质具有可行性,小颗粒面絮含量多,有利于提高面条品质;大颗粒面絮含量多,不利于提高面条品质。     

Comparison of different digesta collection methods to determine the apparent digestibilities of the nutrients at the terminal ileum in pigs

Three different cannulation techniques in pigs were tested with 15 crossbred castrates. Four pigs were fitted with a simple T-cannula, six pigs with a postvalve T-caecum cannula (PVTC cannula) and five pigs with ileocaecal reentrant cannulas. Four diets were tested: a conventional diet, a pectin-rich diet, a crude fibre-rich diet and a semisynthetic diet. For quantitative collection of ileal digesta the PVTC cannulation technique was tested for homogeneity of sampling. Cr₂O₃ and TiO₂ were used as solid phase markers and Co-EDTA as a liquid phase marker. The digestibilities of dry matter, nitrogen, crude fibre, ADF and NDF were determined. Digestibilities measured with re-entrant cannula as a quantitative collection method were sometimes significantly higher (P < 0.05) than with the other cannulas. After correction to 100 % Cr recovery the differences were reduced to less than 5%. Nitrogen digestibility measured with the re-entrant cannula was lower than with the PVTC cannula in the fibre-rich and semisynthetic diets. The Crrecovery was mostly lower than 100%, except with PVTC cannulas and the semisynthetic diet. The recovery rates of Co were higher than those of Cr. In the semisynthetic diet, recoveries of Co and Cr were similar. The recovery rate of TiO₂ with the semisynthetic diet was lower than that of the other two markers. The recovery rates of the markers depended on fibre contents of diets. With the pectin-rich and fibre-rich diets the Cr and Co recoveries were lower than with the control diet. In general, digestibility coefficients measured with the three different cannulation techniques were different. However, when corrections were made for marker recoveries there were only small differences.     

大豆蛋白水解物中肽分子分布的研究

研究采用超滤法与凝胶过滤色谱（GFC）相结合实验方法就大豆蛋白酶解产物寡肽混合物的分子量的分布状况进行了测定,研究结果表明,木瓜蛋白酶与Asl.398蛋白酶的酶解物中以分子量在1000D以下的小肽为主：木瓜蛋白酶解产物中分子量1000D以下的占63.9%,1000-2000D之间的4.64%,2000-4000D之间的占8.21%,4000-10000D之间的占8.20%,分子量10000D以上的占15%;Asl.398蛋白酶酶解物中分子量1000D以下的占72.1%,1000D-2000D的占6.42%,2000D-4000D之间的占2.5%,4000-10000D之间的占3.92%,10000D以上的占15%。     

改性棉活性染料的染色性能分析

采用阳离子改性剂对棉纤维进行阳离子化改性,通过单因素试验分析得到优化的染色工艺,并比较了采用优化染色工艺、同一颜色不同型号的14种活性染料上染改性棉纤维的染色性能,挑选出最适合此工艺、此改性剂的四种活性染料。并再次用这四种染料对原棉和改性棉进行了染色,并比较其上染率和固色率。     

Indirect prediction of herd life in Guernsey dairy cattle

Production and type data were used to investigate the relationships of these traits with herd life data in US Guernsey cows that calved from 1985 through 1990. Two definitions of herd life were used: actual days from birth to disposal (true herd life) and herd life adjusted for milk production (functional herd life). Genetic parameters were calculated with data from cows that had an opportunity to reach 84 mo of age (n = 18,725). Linear type traits were preadjusted for stage of lactation and age at classification. True herd life was preadjusted for age at first calving and for functional herd life, within herd-year quartile ranking for milk yield. The (co)variance components for true and functional herd life, milk, fat, protein, and 15 linear type traits were estimated with multiple-trait REML in an animal model. Heritability estimates for true and functional herd life were 0.12 for both traits. Estimated genetic correlations of herd life with body size traits were from -0.14 to -0.29, with feet and leg traits were from -0.10 to 0.06, and with udder traits were from -0.09 to 0.24. These correlation parameters were used for indirect prediction of herd life from available production and type information in Guernseys.     

Application of native and phosphorylated tapioca starches in potato starch noodle

Summary Characteristics of potato starch noodles substituted with native, phosphorylated and commercial phosphorylated (MTS283) tapioca starches were evaluated. Substitution of up to 17% with phosphorylated tapioca starch or up to 35% with MTS283 improved the quality of potato starch noodles. The resulting noodles were transparent and less brittle when uncooked, and were moderately elastic, less sticky and experienced lower cooking loss and less swelling when cooked. Substitution with native tapioca starch of up to 17% was also possible, but the uncooked noodles were less transparent and the cooked noodles swelled more and were less elastic.     

Visual attractiveness depends on colorfulness and color contrasts in mixed salads

The aim of the study was to investigate the impact of color and color combinations on visual attractiveness in food. Ten salad mixes were composed to represent pale-colored salads with no color contrasts and colorful salads with high color contrasts. A consumer study was conducted to discover the kind of color combinations that are seen as visually attractive in salad mixes. The salad portions were photographed and the photographs were introduced in the consumer study (n = 93). In addition, the color values (L*, a*, b*) of the salad compounds were measured using digital image analysis. The color dimensions chroma, saturation, vividness, depth and hue angle were calculated. The total color differences and the maximum differences between the salad components’ color values and color dimensions were calculated to describe the color contrasts in the salad portions. The results of the study indicated that colors and color combinations impacted visual attractiveness and that colorful salad portions with high color contrasts between salad components were more attractive than pale-colored salads with no color contrasts. Saturation and depth of color were the color dimensions associated with attractiveness. Color contrasts with the complementary colors red and green and with light and dark colors were preferred, along with high total color differences. The colorfulness and the color contrasts were associated with freshness, variability and complexity, and consequently with attractiveness. The improvement of visual attractiveness in food using intensive colors and stimulating color combinations is one potential way to tempt consumers to choose and consume more vegetables.     

包装方式对番木瓜汁品质的影响

以番木瓜破碎打浆制成的番木瓜汁(未灭菌)为研究对象,以总糖、总酸、Vc、顶空CO2和O2含量等为品质判定指标,研究普通、真空、充O2、充CO2包装4种包装方式对番木瓜汁贮藏过程中品质的影响。结果表明,随着贮藏时间的延长,包装番木瓜汁总糖含量不断减小,总酸含量不断上升。其中,普通包装番木瓜汁各指标变化速度最快;真空包装番木瓜汁总糖和总酸含量变化速度较快,但CO2上升速度和Vc损失较小;充O2包装番木瓜汁总糖和总酸含量变化较慢,但CO2上升速度和Vc损失较大;充CO2包装番木瓜汁总糖、总酸、Vc、CO2含量变化均较慢,保质效果相对较好。     

芝麻油掺棕榈油鉴别方法的研究

以4种不同熔点棕榈油与4种芝麻油所配制的128个掺伪芝麻油样品为原料,分别采用全样脂肪酸组成分析法、Sn-2位脂肪酸组成分析法和甘三酯结构分析法对芝麻油中掺棕榈油的鉴别方法进行了研究。结果表明:在全样脂肪酸组成分析法中,当以棕榈酸为标准与芝麻油纯样和国标数据比较时,检出限分别为5%和15%。在Sn-2位脂肪酸组成分析法和甘三酯结构分析法中,当与芝麻油纯样数据比较,分别以亚油酸与棕榈酸含量比值(18:2/16:0)和β-POO(Sn-1-棕榈酸-2,3-二油酸甘油酯)含量为判断标准时,检出限分别为20%和12%。综合这3种方法的检出限高低及分析操作难易程度,初步得出结论:在芝麻油掺棕榈油的鉴别方法中,全样脂肪酸组成分析法是最好的鉴别方法,其余2种方法一般不优先采用,但可作为对上述方法的验证与补充。