竹子硫酸法间歇蒸煮过程纸浆卡伯值机理数学模型研究

研究了竹子硫酸盐法间歇蒸煮过程有效碱浓度的数学模型以及其参数的确定方法.根据蒸煮化学脱木素动力学,利用有效碱浓度数学模型、卡伯值与木素的函数关系,推导出竹子硫酸盐法间歇蒸煮过程纸浆卡伯值机理数学模型,并进行了实验验证.使用卡伯值机理数学模型进行预测时,结果表明其具有理想的预测准确性.由于模型具有较理想的工艺变化适应能力,且方法简单易行,有望应用于生产控制.     

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。     

纸浆卡伯值的控制系统

在蒸煮脱木素的主要反应阶段,浆中木素含量与药液中的有效碱含量有良好的线性关系,终点木素与H因子有关,只要能控制蒸煮终点的H因子,也就控制了脱木素速度和程度——纸浆的卡伯值。如何以H因子控制卡伯值,目前在国外已形成两个比较成熟和完整的控制系统。一个是先期发展的ASEA—MODO卡伯值间歇(Kappa Batch)控制系统,另一个为后期发展的连续蒸煮Measurex传感器控制系统。     

速生桉木硫酸盐浆氧脱木素过程中甲醇生成的动力学模型

考察了速生桉木硫酸盐浆氧脱木素过程中,温度、氧压、NaOH用量及时间对甲醇生成的影响,并据此建立了预测甲醇生成量的动力学模型。结果表明,该模型对初始卡伯值为32.8(高卡伯值)和16.9(低卡伯值)的纸浆在氧脱木素过程中甲醇的生成量均能得到很好的预测(R2分别为0.986和0.974);高、低两种卡伯值纸浆氧脱木素过程中甲醇生成反应的活化能、NaOH浓度及氧压的反应级数分别为55.4、49.3 kJ/mol,1.02、0.362及0.472、0.299;高卡伯值纸浆可有效减少脱木素过程中的甲醇生成量(对后续氧脱木素目标卡伯值为10的生产工艺,甲醇生成量可减少12%)。对不同原料碱法浆氧脱木素过程中降低单位卡伯值的甲醇生成量进行比较,结果表明,阔叶木浆最多(29.1 mg/L)、麦草浆次之(13.8 mg/L)、针叶木浆最少(11.0 mg/L)。     

尾叶桉低卡伯值KP浆一级深度脱木素蒸煮研究

进行了尾叶桉低卡伯值浆硫酸盐法一级深度脱木素蒸煮正交实验,并与常规硫酸盐法蒸煮作了对比实验研究,结果表明:一级蒸煮能够制取低卡伯值浆料,达到深度脱木素的目的,在浆料黏度不损失的前提下,卡伯值较常规硫酸盐法蒸煮低近4个单位。     

甘蔗渣碱法浆和碱-AQ法浆的氧脱木素

在甘蔗渣碱法制浆过程中,在恒定的H因子蒸煮条件下,添加微量的蒽醌(对于绝干原料重量的0.1%),可降低浆料的卡伯值40%(从碱法制浆的21.5降低到碱-AQ法的13.3).用氧气对碱法和碱-AQ法浆延伸脱木素,将进一步降低浆料的卡伯值50%(分别为11.8和6.8).两种浆在氧脱木素时得率略有损失.氧脱木素虽然轻微影响粘度和纤维强度,但是大大地提高了亮度.氧脱木素浆的较低卡伯值,将大大减少漂白时的化学品用量,这正是我们从经济和环保角度所期待的.     

竹材热水预抽提对硫酸盐法制浆的影响

以绿竹为原料,采用不同热水预抽提时间以及蒸煮前将热水预抽提液与竹片分离的方法,通过对比KP法制浆黑液残碱含量以及KP浆的卡伯值、得率、黏度含量等探讨了对硫酸盐法制浆性能的影响。结果表明：热水预抽提可以提高竹片蒸煮脱木素效率,达到相同的脱木素程度（相同卡伯值20）可节省约52%的有效碱用量。在预抽提时间80 min时,浆料的最低卡伯值为7.03。另外,预抽提工艺有利于提高纸浆的黏度,同时纸浆的得率也产生了较大的下降。     

无氯制浆

卡米尔公司设计了一条无氟制浆生产线,其主要方法是:等温蒸煮之后,通过氧气处理,使脱木素至很低的卡伯值,同时保持浆有高的强度;然后通过H_2O_2漂白和中浓O_3漂白等过程。等温蒸煮缓和的连续蒸煮(MCC)是能使漂前的蒸煮和氧脱木素至卡伯值很低的一个过程,因此化学药品的消耗及漂白废液中具有吸附性的有机卤素(AOX)和COD的量都减少了。人们几年前就知道,通过添加白液到蒸煮器高温循环区和提高高温洗涤区的温度,可进一步降低卡伯值。该公司将高温洗涤区完全合并到逆流(对流)蒸煮段,大大增强了脱木素过程的选择性,然后通过氧脱木素段处理,送至漂白段浆的卡伯值可降低到10     

加勒比松深度脱木素的方法及脱木素反应动力学

对加勒比松深度脱木素的方法－硫化钠预处理硫酸盐－ＡＱ法蒸煮进行了研究，结果表明：加勒比松木片经过Ｎａ２Ｓ预处理后进行硫酸盐－ＡＱ法蒸煮，可以获得卡伯值２０以下的低硬度纸浆。预处理段的Ｎａ２Ｓ浓度提高、加入ＡＱ和ＡＱ分散剂，能提高蒸煮脱木素速率，可进一步降低纸浆的硬度；第一级预处理后经过洗涤再进行第二级蒸煮，纸浆的硬度可以下降２个单位。蒸煮过程脱木素规律的结果表明，Ｎａ２Ｓ预处理阶段，木素溶出很少，     

硫酸盐法蒸煮白液中加甲醇的好处

不少研究成果已表明，甲醇加入普通硫酸盐法中可以加速脱木素作用和保护碳水化合物在蒸煮过程中不受或少受降解。试验研究所用原料为白桦木片，厚度2一6mm，液比4:1，蒸煮后木片在5％浓度分离纤维和纸浆用热水洗后，用标准方法测定机械强度。蒸煮用活性碱Na_2O17.5％，蒸煮温度165℃。测得的纸浆卡伯值、得率和粘度列于表1。从表1所列结果，计算了三个参数的回归方程式：卡伯值：在规定H一因子=800时，当硫化度和甲醇浓度增加时，由图1可见纸浆卡伯值降低，而较低的卡伯值表示在有甲醇时木素易于溶出。H一因子=800活性碱=17.5%得率：得率=…     

高效液相色谱法测定成熟龙眼各部位游离鞣花酸含量

采用高效液相色谱法测定石峡、储量两个品种成熟龙眼各部位游离鞣花酸含量。鞣花酸提取条件为80%甲醇溶液,70℃回流2h。色谱条件为:C18色谱柱(250mm×4.5mm,5μm)、柱温35℃、进样体积10μL、检测波长254nm、流速1mL/min,流动相为甲醇-水-冰乙酸(50:49.7:0.3,V/V)。鞣花酸在1～200μg/mL范围内与峰面积呈线性关系,相关系数为0.999。取5个样品瓶分别进样,得到样品保留时间相对标准偏差(RSD)值为1.0%,峰面积RSD值为0.8%。对同一瓶样品连续进样10次,保留时间和峰面积的RSD值分别为0.15%和0.2%。加标回收结果表明平均加标回收率为95.97%～101.9%。测定结果表明石峡和储量各部位鞣花酸的含量大小顺序均为果核>果皮>果肉,其中果皮和果核中鞣花酸远大于已报道的其他水果中的含量。     

Short communication: Effects of drying and analytical methods on nitrogen concentrations of feeds,feces, milk,and urine of dairy cows

Nitrogen concentrations in feeds, feces, milk, and urine samples were measured using 2 analytical methods following different drying procedures. Ten samples of corn silage, alfalfa silage, and concentrates collected from 2017 to 2018 at Krauss Dairy Research Center, The Ohio State University (Wooster), were used. A 4-d total collection digestion trial provided fecal samples from 10 cows (1 sample/cow), and another 10 cows were used to collect milk samples (1 sample/cow) and spot urine samples (1 sample/cow). Spot urine samples were acidified immediately to pH <3.0 when collected. Feed samples were oven dried (55°C) or lyophilized and analyzed using the Kjeldahl (KJ; copper sulfate as a catalyst) method and a combustion method (elemental analyzer; EA). Feces, urine, and milk samples were analyzed for N using the following methods: (1) fresh samples by KJ (referred to as wet KJ), (2) lyophilization (urine and milk for 8 h; feces for 120 h) followed by EA (LYO-EA), and (3) oven drying (milk and urine for 1 h; feces for 72 h at 55°C) followed by EA (OD-EA). Additionally, changes in N content of acidified urine at −20° over 180 d of storage were examined. Nitrogen concentrations in corn silage, alfalfa silage, and concentrates were greater for EA by 6.1, 4.8, and 8.3%, respectively, compared with KJ. Analysis of dried samples via EA compared with wet KJ resulted in lower fecal N content (27.8 vs. 29.3 g/kg of DM). Nitrogen concentration in fecal samples via KJ after lyophilization was lower by 5% compared with wet KJ but did not differ from LYO-EA, suggesting that N losses occurred during drying. Nitrogen determination with EA after drying of samples resulted in greater milk N (5.70 vs. 5.50 g/kg) and urinary N (9.16 vs. 9.06 g/kg) content compared with wet KJ. However, drying method (i.e., lyophilization vs. oven drying) did not affect N content of milk, urine, or feces. The use of EA resulted in lower percentage deviation of N content from duplicate sample assays for most samples (no difference was found for concentrate and fecal N), suggesting that EA was more precise than KJ. In conclusion, drying of feces caused N losses regardless of drying methods. For urine and milk samples, if drying is necessary (i.e., EA), oven drying at 55°C can be used rather than lyophilization. The N content was greater in feeds, milk, and urine when determined with EA versus KJ. In addition, N content in acidified and undiluted urine at −20° changed and should be analyzed within 90 d of storage. The results in the current study, however, did not account for laboratory-to-laboratory variation.     

鞣花酸和石榴皮多酚提取物抗氧化活性的比较

对鞣花酸提取物(EA)和石榴皮多酚提取物(PE)的抗氧化活性进行比较研究。通过HPLC法检测EA和PE中鞣花酸的含量,Folin-酚法检测PE中总多酚含量;采用H2O2处理HepG2细胞建立细胞氧化应激损伤模型,MTT法比较不同浓度的EA和PE对HepG2细胞氧化应激损伤的保护作用;采用DPPH法、·OH清除法检测PE和EA体外抗氧化作用。结果表明:与EA相比,PE中鞣花酸含量很低,但PE和EA均以剂量依赖的方式提高氧化损伤的HepG2细胞生存率,有显著的保护作用,且在同一的浓度下,PE的保护作用显著高于EA。PE和EA对DPPH法、·OH清除法的清除率均呈剂量依赖性增强。     

Development and validation of gas chromatography and real‐time quantitative PCR for the quantification of landscape‐scale gene flow from varieties of high erucic acid (HEAR) oilseed rape

BACKGROUND: High erucic acid oilseed rape (HEAR) was tested as a source crop for estimates of regional geneflow. Two methods to detect HEAR in low erucic acid oilseed rape (LEAR) were compared: real‐time quantitative PCR (qPCR) and gas chromatography (GC). RESULTS: Fields (2.5 ha) of a LEAR variety (0.028% EA) in Tayside and Hertfordshire were juxtaposed adjacent to and 1 km distant from a HEAR (44% EA) field. The LEAR variety was a varietal association to ensure high cross‐pollination (CP). The methods were highly correlated, measuring between 30% and 0.5% CP. However, the qPCR method became unreliable below 0.5% CP, whereas GC was robust enough to detect raised EA equivalent to one F1 seed in 500 (0.2%). A statistical mixture model was fitted to the distributions of EA in samples in order to assign a CP value to each 500‐seed sample. Declines of CP from 30% to < 1%, and EA from 5% to 0.2%, with distance up to 150 m in the near fields was best fitted with a power function. The combined mean EA for both far fields was 0.11%, well above the background LEAR value of 0.028%, and mean CP was 0.36%. CONCLUSIONS: The GC method of detection raised %EA should be a reliable and high‐throughput means of estimating %CP between fields, provided the %EA of single F1 seed in receptor fields is measured to confirm the presence of F1 seed. Copyright © 2008 Society of Chemical Industry     

鞣花酸对马兜铃酸I诱导小鼠急性肾损伤的保护作用

目的：研究鞣花酸（ellagic acid,EA）对马兜铃酸I（aristolochic acids I,AAI）诱导的急性肾损伤的保护作用。方法：40?只昆明小鼠（雌雄各半）随机分为健康组、模型组（10?mg/kg?mb?AAI）、EA低剂量组（10?mg/kg mb?AAI＋10?mg/kg?mb?EA）和EA高剂量组（10?mg/kg?mb?AAI＋30?mg/kg?mb?EA）,EA不同剂量组小鼠每天灌胃不同剂量的EA,从第7天开始,腹腔注射AAI建立急性肾损伤模型,然后灌胃给予不同剂量的EA,12?d后处死小鼠;检测肾脏指数、尿蛋白、尿素氮和肌酐水平等肾功能指标;苏木精-伊红（hematoxylin-eosin,HE）和Masson染色检测肾脏组织病理学变化;检测肾脏内氧化应激指标（包括还原型谷胱甘肽（glutathione,GSH）、总超氧化物歧化酶（total superoxide dismutase,T-SOD）和丙二醛（malondialdehyde,MDA）水平）,检测小鼠体内炎症因子水平;通过免疫印迹和定量聚合酶链式反应检测肾脏中核因子（nuclear factor,NF）-κB和NOD样受体蛋白3（NOD-like receptor protein 3,NLRP3）通路相关因子的表达。结果：与模型组相比,EA能显著改善肾损伤模型小鼠的各项肾功能指标以及肾脏组织病理学变化,恢复肾组织中氧化应激指标到接近正常水平;此外,与模型组相比,在EA的作用下小鼠血清中炎症因子肿瘤坏死因子-α（tumor necrosis factor-α,TNF-α）和白细胞介素（interleukin,IL）-1β水平下降,肾脏中TNF-α和IL-1β编码基因的转录水平亦有明显下降;进一步研究发现,与模型组相比,EA能显著下调小鼠肾脏内NF-κB抑制蛋白（inhibitor of NF-κB,IκB）α和NF-κB p65蛋白的磷酸化水平（P＜0.05,P＜0.01）,抑制NLRP3炎性小体各组分（包括NLRP3、凋亡相关斑点样蛋白（apoptosis-associated speck-like protein,ASC）、半胱氨酸蛋白酶（Caspase）-1和IL-1β的转录和翻译。结论：EA对AAI诱导的小鼠急性肾损伤具有保护作用,其机制可能与通过干预NF-κB/NLRP3通路阻断AAI所致的肾脏内炎症反应紧密相关。     

海参皂苷Holothurin A和Echinoside A对肥胖小鼠尿酸代谢的影响

Holothurin A (HA)和Echinoside A (EA)是海参中含量较高的两种皂苷,本研究分析了HA和EA对db/db肥胖小鼠血尿酸、尿酸代谢相关酶活性及肾脏尿酸代谢相关转运体mRNA表达的影响。将db/db小鼠按体重分成模型组、HA组、EA组,每组8只,C57/BL6小鼠为对照组,HA组、EA组饲料分别添加0.07%两种海参皂苷单体,喂养2周。结果显示,相比对照组小鼠,模型组小鼠表现为血清尿酸水平显著升高,海参皂苷HA与EA分别降低血尿酸12.7%和18.1%（P<0.05）,并显著改善肾脏肾小球组织结构病理学变化。实验结果表明,海参皂苷对db/db肥胖小鼠肝脏黄嘌呤氧化酶和腺苷脱氨酶的活性无显著影响(P>0.05),但显著上调肾脏尿酸代谢相关转运体GLUT9、OAT1、OCTs、OCTNs 的mRNA表达水平（P<0.05）。海参皂苷HA和EA可能通过调控肾脏尿酸代谢相关转运体改善尿酸代谢异常,其中EA改善效果优于HA。该研究成果为膳食海参皂苷预防尿酸代谢异常提供理论依据。     

真空包装低盐发酵酒糟鱿鱼货架期预测的研究

将酒糟鱿鱼贮藏在0、4℃、20℃、30℃、40℃条件下,测定了其总菌落数、挥发性盐基总氮(TVB-N)与感官品质指标的变化。在Arrhenius动力学方程基础之上,建立动力学模型。结果表明,菌落总数变化预测模型中的活化能(EA)及速率常数(k0)分别为:71.26 kJ/mol和3.987×1013,挥发性盐基氮变化的活化能(EA)及速率常数(k0)分别为:68.86 kJ/mol和2.159×1012。酒糟鱿鱼的总菌落数、挥发性盐基总氮随着贮藏时间的延长而增加,其感官品质指标随着贮藏时间的延长而下降。该试验建立的酒糟鱿鱼货架期预测模型准确率达到±10%以内。     

福建养殖仿刺参抗氧化多肽的酶解工艺优化及其对过氧化氢诱导的血管内皮细胞EA.hy926损伤的保护作用

目的:优化仿刺参抗氧化多肽的酶解工艺,并研究其对过氧化氢(hydrogen peroxide,H₂O₂)诱导的人脐静脉内皮细胞株EA.hy926损伤的保护效应。方法:以酶解产物的水解度、体外DPPH自由基清除率为指标,筛选出最适蛋白酶;在单因素实验基础上,选取温度、加酶量、pH作为影响因子,以体外DPPH自由基清除率为响应值,结合响应面试验优化酶解工艺条件;进一步探讨酶解多肽体外抗氧化活性。以MTS法检测低、中、高剂量组的仿刺参抗氧化多肽对H₂O₂诱导的血管内皮细胞损伤的保护作用,以MDA含量、SOD活力测定细胞氧化及抗氧化水平。结果:动物蛋白水解酶为最适蛋白酶,酶解工艺优化条件为:料液比1:20 g/mL、酶解时间2 h、酶解温度50℃、加酶量7000 U/g、pH7.5,该条件下制备的仿刺参多肽体外DPPH自由基清除率为68.81%,与模型预测值(68.35%),相对误差为1%,回归模型可靠。酶解多肽对DPPH自由基、羟自由基(·OH)、超氧阴离子自由基(O₂-·)和ABTS自由基(ABTS+·)的半数抑制浓度IC₅₀分别是9.01、0.63、10.89和20.53 mg/mL,说明其具有较好的体外抗氧化活性。选取200 μmol/L浓度H₂O₂建立细胞损伤模型,与H₂O₂组相比,中、高剂量组仿刺参抗氧化多肽能明显抑制H₂O₂诱导的血管内皮细胞氧化损伤,降低MDA含量,提高SOD活力。结论:采用动物蛋白水解酶酶解优化工艺制备的仿刺参抗氧化多肽对人脐静脉内皮细胞EA.hy926具有显著的保护作用并呈显著的剂量-效应关系。     

Physical properties of egg albumen and cassava starch composite network formed by a salt-induced gelation method

Effect of cassava starch (CS) filler on the physical properties of egg albumen (EA) and cassava starch composite (EA–CS) gels and films was investigated using EA as the continuous matrix embedded with CS granules. The composite network was formed at 55 °C; below the thermal gelation temperature of both EA and CS, using the salt-induced gelation method. Increasing the pH from 8 to 11 and NaCl from 50 to 200 mM resulted in a softer but more cohesive EA gel (p ⩽ 0.05). Raising CS content increased Young’s modulus, stress and opacity but reduced the cohesiveness of the mixed gel network (p ⩽ 0.05). The release of paprika oleoresin (O/R) from the dried EA–CS composite film into the oil phase was determined as the effective diffusion coefficient (D_eff) based on Fick’s second law of diffusion. D_eff of O/R decreased with increases in the strength and elasticity of the composite film and relative humidity (RH) during film aging. Overall, the study showed that the salt-induced gelation method could be used to form an EA–CS composite film at room temperature. In addition to the strength and elasticity of the protein network, RH during aging could also provide a mean to regulate the controlled-release properties of such a composite film.     

一种用于样品前处理的加液仪控制系统设计

针对人工检测食品或者化学样本时,前处理误差大、效率低等问题,设计了一套用于样品前处理的加液仪控制系统。该系统采用PLC作为主控制器,根据前处理仪的控制需求,对系统的软硬件进行设计。结合S型加减速算法的特性和非接触式加液的特点,通过控制加液过程中减速阶段的加速度,让针尖悬挂液滴更好地脱落,提出了一种适合加液的分段式电机控制模型,并对加液体积进行了拟合分析和误差补偿。试验结果表明,其加液误差在±0.5%以内,满足了前处理仪设计的加液精度要求(±1%),且具有96个样品位,适合大批量的样品进行前处理。