楸树枝桠材硫酸盐法制浆的研究

对楸树3个无性系的两类径级枝桠材的硫酸盐化学法制浆及造纸性能进行了研究.研究结果表明:粗、细枝桠材硫酸盐法蒸煮最佳用碱量分别为21%和22%(以Na2O计).在此条件下蒸煮,可获得卡伯值为2l、纸浆得率分别为41%和34%的未漂化学浆.在相同的蒸煮工艺条件下,两类径级的楸树枝桠材硫酸盐法制浆性能表现出明显的差异.楸树3个无性系枝桠材硫酸盐法制浆性能差别不十分明显,在相同蒸煮条件下所得纸浆的卡伯值、纸浆得率和筛渣率相近.8401枝桠材硫酸盐浆相对较难漂白,8402和金丝楸硫酸盐浆的可漂性相对较好.     

树皮和腐朽木片对松木硫酸盐法蒸煮的影响

硫酸盐法蒸煮时,商品松木片原料中树皮含量须控制在8%以下;进一步实验表明,在树皮含量相同时,增加腐朽木片的含量,卡伯值、细浆得率、黑液残碱和蒸煮浆粘度都有不同程度的降低,并且树皮含量对卡伯值的影响较腐朽木片含量的大;当树皮和腐朽松木含量分别控制在2%和10%时,可获得较低的卡伯值和较为理想的细浆得率。     

汉麻芯秆烧碱-蒽醌碱法制浆性能研究

利用烧碱-蒽醌碱法制浆工艺对育种田汉麻芯秆和纤维田汉麻芯秆进行蒸煮,研究用碱量对二者成浆性能的影响。结果表明,当蒸煮温度160 ℃、保温时间2.5 h时,随着用碱量的增加,2种浆料的粗浆得率和高锰酸钾值逐渐下降,纤维素含量和保水值逐渐提高;当用碱量为20%时,育种田汉麻芯秆浆和纤维田汉麻芯秆浆的粗浆得率分别为48.3%和56.8%,高锰酸钾值分别为11.0和13.9,纸浆得率和性能相对较优。将打浆度均为40 °SR的这2种汉麻芯秆浆（纤维长度约1~3 mm）分别与针叶木浆（打浆度40 °SR）按一定配比混合抄纸发现,配抄5%汉麻芯秆浆可改善纸张的强度性能,表明汉麻芯秆浆可作为生产箱纸板面层纸或牛皮纸等的替代原料。     

不同生长期绿洲一号和巨菌草制浆性能探讨

采用超声辅助预处理及蒸煮对1年、2年和3年不同生长期的绿洲一号及巨菌草的制浆性能进行了评价。结果表明,在相同制浆工艺条件下(超声波预处理用碱量4%,硫化度2%,超声时间2 h;蒸煮用碱量6%,硫化度0,固液比1∶4,最高温度170℃,保温时间1 h),3年生巨菌草较适合作为制浆原料,其制浆的粗浆得率49.3%,卡伯值14.5,纸浆黏度850.63 mL/g,白度39.3%。超声波预处理液中木素含量4.3 g/L,还原糖含量2.9 g/L,蒸煮黑液中木素含量2.9 g/L,还原糖含量5.7 g/L。抄造纸张抗张指数56.4 N·m/g,撕裂指数20.5 mN·m~2/g,耐破指数2.35 kPa·m~2/g。     

慈竹模拟置换蒸煮工艺研究

研究了慈竹模拟置换蒸煮过程中预浸渍段、温充段、热充段NaOH浓度及硫化度对置换蒸煮的影响。结果表明,在慈竹模拟置换蒸煮过程中,在一定范围内NaOH浓度升高时,有利于药液向慈竹内部的渗透,利于蒸煮;温充段对脱木素的贡献大于预浸渍阶段;热充段NaOH浓度对深度脱木素影响最显著。硫化度从23%提高到44%时,利于深度脱木素,浆料卡伯值下降显著,同时得率也随之下降。当预浸渍段、温充段、热充段的NaOH浓度分别为10、15～20、30 g/L,硫化度为23%～30%时,浆料卡伯值为10.7～17.8,得率为43.1%～45.1%。置换蒸煮与普通蒸煮相比,当成浆得率相当时,置换蒸煮成浆卡伯值较低;当卡伯值相当时,置换蒸煮成浆得率较高。     

卡伯值对麦草浆DQP漂白污染负荷影响的研究

使用同一卡伯因子对不同卡伯值的麦草未漂浆进行DQP漂白,研究污染负荷及浆料性能的变化情况。结果表明,漂白废水的COD_Cr、BOD₅及AOX负荷随未漂浆卡伯值的降低而降低,漂白浆的白度随未漂浆卡伯值的降低而升高。未漂浆卡伯值每增加1个单位,DQP漂白废水COD_Cr负荷增加2.6 kg/t浆左右,BOD₅负荷增加0.6 kg/t浆左右;AOX负荷均较低,为0.5~0.7 kg/t浆。未漂浆经DQP漂白后强度性能较好,且未漂浆卡伯值越高,漂白浆强度性能越好。     

高卡伯值尾叶桉硫酸盐浆的蒸煮及其性能研究

本文研究了不同条件下尾叶桉硫酸盐法蒸煮的纸浆卡伯值和H因子,纸浆得率、HexA含量和黏度及基于总固形物的残碱含量与卡伯值的关系.结果表明,尾叶桉高卡伯值硫酸盐法蒸煮的特征卡伯值为40,其对应的H因子和较优的活性碱用量分别约为297和19%～20%,此时的细浆得率为52%.当纸浆卡伯值随蒸煮条件的加剧低于该特征值而又大于16时,继续蒸煮不但会导致纸浆得率和黏度的下降以及有效碱消耗的增加,同时纸浆中HexA含量也逐渐增大.     

近红外光谱分析法预测欧美杨的制浆性能

选取85个欧美杨样品,先进行蒸煮实验,用国家标准方法测定样品的卡伯值和得率,然后用近红外光谱仪采集欧美杨浆样的近红外光谱图。光谱分别进行预处理后,用偏最小二乘法和完全交互验证方式建立相应预测模型。卡伯值校正模型和预测模型的相关系数分别为0.9445和0.9607,校正标准差和预测标准差分别为1.100和0.936;得率校正模型和预测模型的相关系数分别为0.8792和0.8617,校正标准差和预测标准差分别为0.844和0.831。结果表明,近红外光谱法可以快速分析浆样的卡伯值和得率。     

预水解对硫酸盐蓝桉浆主要性质的影响性能的影响

进行了预水解硫酸盐蓝桉浆性能的研究。首先对蓝桉木片进行了5个级别的水预水解,然后对水预水解木片进行硫酸盐法蒸煮以得到3种不同卡伯值的硫酸盐蓝桉浆。实验从浆料组分、蒸煮条件、成浆卡伯值及得率、黏度、浆料纤维形态、浆料纤维表面性能及成纸主要强度性能等角度探讨了预水解对后续的硫酸盐法制浆的影响。结果表明,经过预水解的硫酸盐浆半纤维素含量从未预水解的21%~22%降到3%~4%,而纤维素含量从73%~75%增加到85%~90%。经过预水解的所有纸浆纤维长度均降低且纤维扭结指数大幅度增大。采用反相气相色谱分析法测出未预水解浆样和预水解120 min后制浆(成浆卡伯值为15)的浆样的表面能色散分量分别为30.8和34.9 mJ/m2。实验提出了2个模型方程来预估预水解中木片的质量损失和成浆卡伯值。     

蒸煮条件对硫酸盐法竹浆性能的影响

采用CAS-420型油浴蒸煮器分别对竹子进行高温-短时间硫酸盐法蒸煮及低温-长时间硫酸盐法蒸煮,并将所得浆料进行D0(EOP)D1漂白.比较了未漂浆的得率、黏度、白度、成纸性能及漂白废水的污染负荷.结果表明,相对于高温-短时间蒸煮,低温-长时间蒸煮的浆料得率和黏度较高;经D0(EOP)D1漂白后,两种蒸煮方法所得浆料的白度可达88%左右,漂白浆有较高的黏度和较好的白度稳定性及成纸强度;在相同卡伯值下,低温-长时间蒸煮浆料的漂白废水污染负荷略低.     

Ovarian structures and circulating steroids in heifers and lactating cows in summer and lactating and dry cows in winter

Two experiments compared follicular and luteal development and circulating steroid concentrations from induced luteolysis to ovulation in lactating Holstein cows (n = 27; 40.0 +/- 1.5 kg milk/day) vs. nulliparous heifers (n = 28; 11 to 17 mo-old) during summer (Experiment 1), and in lactating (n = 27; 45.9 +/- 1.4 kg milk/d) vs. dry cows (n = 26) during winter (experiment 2). All females received PGF2,, 6 d after ovulation and were monitored until next ovulation by daily ultrasound and assay of serum progesterone (P4) and estradiol (E2). Every female was used two or three times. In Experiment 1, lactating cows had high incidence of multiple ovulation (63.5%) compared with heifers (1.3%). Among single ovulators, there was no difference in maximal size of ovulatory follicles between lactating cows and heifers (15.8 vs. 16.5 mm, respectively). However, lactating cows had lower peak serum E2 (8.6 vs. 12.1 pg/ml), took longer to ovulate after luteolysis (4.6 vs. 3.8 d), developed more luteal tissue volume (7,293.6 vs. 5,515.2 mm3), and had lower serum P4 on d 6 after ovulation (2.0 vs. 3.0 ng/ml) than heifers (data included multiple ovulators). In experiment 2, multiple ovulations were similar between lactating and dry cows (17.9 vs. 17.2%, respectively). Peak serum E2 was also similar between lactating and dry cows (7.6 vs. 8.5 pg/ml) although lactating cows had larger ovulatory follicles (18.6 vs. 16.2 +/- 0.4 mm). Lactating cows took longer to ovulate (4.8 vs. 4.2 d), developed more luteal tissue (7,599 vs. 5,139 +/- 468 mm3), but had similar serum P4 (2.2 vs. 1.9 ng/ ml) compared with dry cows. Therefore, lactating cows had similar or lower circulating steroid concentrations than dry cows or heifers, respectively, despite having larger ovarian structures.     

Fertilization and early embryonic development in heifers and lactating cows in summer and lactating and dry cows in winter

Two experiments in two seasons evaluated fertilization rate and embryonic development in dairy cattle. Experiment 1 (summer) compared lactating Holstein cows (n = 27; 97.3 +/- 4.1 d postpartum [dppl; 40.0 +/- 1.5 kg milk/d) to nulliparous heifers (n = 28; 11 to 17 mo old). Experiment 2 (winter) compared lactating cows (n = 27; 46.4 +/- 1.6 dpp; 45.9 +/- 1.4 kg milk/d) to dry cows (n = 26). Inseminations based on estrus included combined semen from four high-fertility bulls. Embryos and oocytes recovered 5 d after ovulation were evaluated for fertilization, embryo quality (1 = excellent to 5 = degenerate), nuclei/embryo, and accessory sperm. In experiment 1, 21 embryos and 17 unfertilized oocytes (UFO) were recovered from lactating cows versus 32 embryos and no UFO from heifers (55% vs. 100% fertilization). Embryos from lactating cows had inferior quality scores (3.8 +/- 0.4 vs. 2.2 +/- 0.3), fewer nuclei/embryo (19.3 +/- 3.7 vs. 36.8 +/- 3.0) but more accessory sperm (37.3 +/- 5.8 vs. 22.4 +/- 5.5/embryo) than embryos from heifers. Sperm were attached to 80% of UFO (17.8 +/- 12.1 sperm/UFO). In experiment 2, lactating cows yielded 36 embryos and 5 UFO versus 34 embryos and 4 UFO from dry cows (87.8 vs. 89.5% fertilization). Embryo quality from lactating cows was inferior to dry cows (3.1 +/- 0.3 vs. 2.2 +/- 0.3), but embryos had similar numbers of nuclei (27.2 +/- 2.7 vs. 30.6 +/- 2.1) and accessory sperm (42.0 +/- 9.4 vs. 36.5 +/- 6.3). From 53% of the flushings from lactating cows and 28% from dry cows, only nonviable embryos were collected. Thus, embryos of lactating dairy cows were detectably inferior to embryos from nonlactating females as early as 5 d after ovulation, with a surprisingly high percentage of nonviable embryos. In addition, fertilization rate was reduced only in summer, apparently due to an effect of heat stress on the oocyte.     

2018年深圳市售蔬菜和鸡蛋中氟虫腈及其代谢物的检测分析

目的 建立超高效液相色谱-串联质谱法同时测定蔬菜和鸡蛋中氟虫腈及其代谢物(氟甲腈、氟虫腈砜和氟虫腈亚砜), 并对深圳市售的蔬菜和鸡蛋中氟虫腈及其代谢物残留状况进行抽样检测。方法 采用QuEChERS前处理方法, 以C18色谱柱为分离柱, 以乙腈和10 mmol甲酸+6 mmol甲酸铵水溶液为流动相进行梯度洗脱, 用超高效液相色谱-串联质谱(ultra performance liquid chromatography-mass spectrometry/mass spectrometry, UPLC-MS/MS), 电喷雾电离(electrospray ionization, ESI), 多反应监测(multiple reaction monitoring, MRM)模式检测, 外标法同时定量测定氟虫腈及其代谢物。结果 方法的线性范围为0.1~2.0 μg/L, 线性相关系数均大于0.9994, 检出限0.0005 mg/kg, 定量限0.001 mg/kg; 蔬菜中3个水平的平均加标回收率88.0%~101.2%, 相对标准偏差(relative standard deviation, RSD)均小于8.5%; 鸡蛋中3个水平的平均加标回收率86.1%~104.8%, 相对标准偏差(RSD)均小于9.2%。结论 该方法具有操作简单、干扰少、快速、准确可靠等特点, 可适用于蔬菜鸡蛋中氟虫腈及其代谢物的检测。     

Zinc and iron contents and their bioaccessibility in cereals and pulses consumed in India

Several cereals and pulses commonly consumed in India were screened for zinc and iron contents and their bioaccessibility in the same was determined by equilibrium dialysis employing an in vitro simulated digestion procedure. Zinc content of cereals ranged from 1.08 mg/100 g in rice to 2.24 mg/100 g in sorghum. Zinc content of pulses was between 2.03 mg/100 g (whole chickpea) and 2.68 mg/ 100 g (decorticated chickpea). Iron content of cereals ranged from 1.32 mg% in rice to 6.51 mg% in sorghum, while that of pulses ranged from 3.85 mg% in decorticated green gram to 6.46 mg% in black gram. Dialyzability of zinc from pulses (27–56%) was generally higher than that from cereals (5.5–21.4%). Dialyzabilities of iron were almost similar from both cereals and pulses examined and were 4.13–8.05% in cereals and 1.77–10.2 % in pulses. A significant negative correlation between inherent phytate content and zinc dialyzability value was inferred in the case of pulses. Phytic acid content of the cereals had a significant negative influence on iron dialyzability. Inherent calcium had a negative influence on zinc dialyzability in cereals. Tannin did not have any significant influence on zinc or iron dialyzabilities from cereals and pulses. While both insoluble and soluble fractions of the dietary fibre generally interfered with zinc dialyzability, the insoluble fraction alone had this effect on iron dialyzability. The lower collective negative influence of the inherent factors on zinc dialyzability from pulses is consistent with their higher concentrations in these grains, relative to cereals. The negative correlation of inherent phytic acid with zinc and iron dialyzabilities was supported by enhanced dialyzabilities of these minerals upon partial removal of phytate from the grains by treatment with fungal phytase.     

果蔬及其制品中真菌毒素的污染与检测研究进展

果蔬在生长、贮存、运输及加工等一系列过程中,极易受到各种病原菌的侵染而发生腐烂,腐烂果蔬不仅造成巨大的经济损失,而且导致果蔬积累大量的真菌毒素。真菌毒素可通过食物链的传递对人或动物的健康带来巨大威胁。本文就果蔬中常见真菌毒素的种类、产毒菌株、侵染途径、产毒条件、毒性作用、检测方法和限量标准等方面进行详细的总结,旨在为果蔬中真菌毒素的控制提供参考。     

蛋白质组学技术及其在乳及乳制品中的应用研究进展

蛋白质组学技术是近年来生命科学研究的重要工具,在食品、医学及动植物研究领域具有独特优势。利用蛋白质组学技术研究乳及乳制品,深入阐明其中蛋白质的表达及动态变化已成为当前的研究热点。该文主要综述了蛋白质组学的概念、常用技术及应用领域,重点介绍蛋白质组学在乳及乳制品领域,特别是在乳脂肪球膜蛋白、乳清蛋白、乳及乳制品加工过程以及干酪制品中的研究应用,探讨了目前乳及乳制品蛋白质组学研究中存在的问题与局限,并对蛋白质组学及其在乳及乳制品中的应用前景进行了总结与展望,为应用蛋白质组学技术深入研究乳及乳制品提供了理论依据。     

冰酒中的毕赤属和汉逊属酵母菌的筛选及其在葡萄酒酿造中的应用

从冰葡萄酒自然发酵过程中分离、鉴定出10株毕赤属(Pichia)和汉逊属(Hanseniaspora)酵母,对其耐受性(酒精、糖、酸、SO2)进行研究,筛选得到4株耐受性能优良的酵母菌株,编号为"HO"和"HU"(Hanseniaspora属)、"PO"和"PK"(Pichia属).再将此4个酵母菌株与商业酿酒酵母(S...     

Fenvalerate residue level and dissipation in tea and in its infusion

Fenvalerate is a non-systemic insecticide/acaricide used in controlling a wide range of pests, including those resistant to organochlorine, organophosphorus and carbamate insecticides. The study investigated the dissipation behaviour (residue level) of fenvalerate in tea and its transfer during infusion. Fenvalerate was applied on tea crop at two dosages, 100 and 200?g a.i.?ha^?1 (recommended and double the recommended) in the dry and wet seasons under field conditions. Samples (green tea shoots, made tea, its infusion and spent leaves) were analysed for fenvalerate by high-performance liquid chromatography using diode array detection. The residue dissipated faster in the wet season than in the dry season. Seven days after the treatment (normal round of plucking) the residues observed in the green shoots at the two dosages were 0.5?±?0.01, 1.1?±?0.01 and 0.4?±?0.02, 0.9?±?0.01?mg?kg^?1 in the dry and wet seasons, respectively. During processing of green tea shoots to made tea a 30–40% loss of residue was observed. The transfer of residue from made tea to infusion was in the range 10–30% for both seasons, whereas 50–70% of the residues remained in the spent leaves. However, the degradation rate in both seasons followed first-order kinetics. The half-lives were in the range of 2–3 days for green shoots and made tea in both seasons.     

Fenvalerate residue level and dissipation in tea and in its infusion

Fenvalerate is a non-systemic insecticide/acaricide used in controlling a wide range of pests, including those resistant to organochlorine, organophosphorus and carbamate insecticides. The study investigated the dissipation behaviour (residue level) of fenvalerate in tea and its transfer during infusion. Fenvalerate was applied on tea crop at two dosages, 100 and 200 g a.i. ha^-1 (recommended and double the recommended) in the dry and wet seasons under field conditions. Samples (green tea shoots, made tea, its infusion and spent leaves) were analysed for fenvalerate by high-performance liquid chromatography using diode array detection. The residue dissipated faster in the wet season than in the dry season. Seven days after the treatment (normal round of plucking) the residues observed in the green shoots at the two dosages were 0.5 ± 0.01, 1.1 ± 0.01 and 0.4 ± 0.02, 0.9 ± 0.01 mg kg^-1 in the dry and wet seasons, respectively. During processing of green tea shoots to made tea a 30-40% loss of residue was observed. The transfer of residue from made tea to infusion was in the range 10-30% for both seasons, whereas 50-70% of the residues remained in the spent leaves. However, the degradation rate in both seasons followed first-order kinetics. The half-lives were in the range of 2-3 days for green shoots and made tea in both seasons.     

生物技术在制浆造纸中的应用与研究进展

介绍了生物技术在制浆造纸工业的应用与研究进展，包括生物制浆、生物漂白、生物脱墨及造纸过程中的生物技术等。