PVA浸渍纸基棉质地膜的制备与表征

摘 要 针对普通塑料地膜严重污染环境的问题,本文选用不长于6mm的废弃棉短绒,经过除杂、制浆、抄造、烘干,然后用4%PVA胶液浸渍处理,实现可自然降解纸基棉质地膜的制备。测试试样的断裂强力、伸长率、撕裂度、耐破度、透光性,采用扫描电镜(SEM)、红外光谱、降解率等方法进行理化性能表征,分析其样品降解前后的性能差异。结果表明：棉质地膜具有良好的物理机械性能,其干、湿断裂强力可达17.0N和10.6N、撕裂度2.48N、耐破度97.8Kpa、可见光透过率达68%;经过49d土埋试验后,棉质地膜的降解率达到了45.5%,说明棉质地膜具有良好的降解性。     

丝胶浸渍棉质非织造地膜的制备与表征

 将棉质半成品水刺非织造布浸渍于不同质量分数的废蚕丝制成的丝胶溶液中,通过二浸二轧工艺烘干定型,实现了可降解棉质非织造地膜的制备。通过灰色关联分析得出影响地膜强度的因素及其排序为:回潮率> 增重率> 丝胶质量分数;采用ESEM、红外光谱、降解率等方法进行理化性能表征,分析其降解前后性能差异。结果表明:浸渍涂层法中胶液质量分数为1 %时,其理化性能最佳,纵横向断裂强力分别为33 N、44 N ,回潮率为1018 %。     

可降解机械竹浆地膜纸研究北大核心

在自制机械竹浆中添加少量针叶木浆及化学助剂制备地膜纸,并将其用于实际作物生长中。结果表明,机械竹浆打浆度为40°SR,机械竹浆与针叶木浆质量比为80∶20,浆内添加10%的聚乙烯醇(PVA)纤维、1.5%淀粉、1.5%纤维素纳米纤丝(CNF)时,所抄100 g/m^(2)地膜纸的干抗张强度为1.52 kN/m,撕裂度为650 mN。在此基础上再添加1.0%PAE和0.15%AKD,地膜纸湿抗张强度为0.74 kN/m,Cobb值为27.7 g/m^(2),水接触角为112.95°。按此配方生产的地膜纸可促进辣椒苗及地瓜藤的生长,并对杂草有良好的抑制效果,且具有良好的可降解性能。     

木屑/粘胶纤维湿法非织造地膜的研制

为改善土壤环境,减少塑料地膜造成的白色污染,采用湿法成网制备以造纸木屑和粘胶短纤维为原料的农用非织造地膜。对非织造地膜的外观形貌和表面结构进行表征,并对其力学性能、渗水性、降解性、透光性进行测试。结果表明：通过调节面密度、纤维混纺比及黏合剂浓度可制得性能良好的非织造地膜;结合40d土埋试验后,非织造地膜的降解率达到70％以上。通过湿法成网制得的地膜具备优良通透性,可有效改善作物生长环境。     

丝棉非织造布用于农用地膜的研究

选用纺织工业生产中产生的废蚕丝和棉纤维为原料、明胶为粘合剂生产的非织造布地膜,在使用过程中易降解,并可改善土壤的肥力,不会造成环境污染。通过正交分析得出最佳棉丝配比。结果表明：随着丝含量的增加,非织造布地膜纵横向强力均有一定程度的增加；可降解地膜的保温效果略小于普通塑料地膜；70 d的降解率超过55%。     

麻丝非织造布农用地膜的研制和性能研究

本文采用亚麻和蚕丝纤维的纺织下脚料制备了麻丝非织造布农用地膜，通过正交试验法对其工艺参数进行优化,并对地膜的农用性能进行了测试。结果表明：亚麻与丝的重量比为96﹕4，平方米克重为35g/m2，粘合剂浓度为12%时制成地膜的断裂强力为30N，厚度为0.1148mm，回潮率为6.7%，透湿率为2217g/(m2•h)，红外分析显示麻丝非织造布地膜可完全自然降解，地膜具有较好的保温性和保墒作用，且地膜降解产物能提高土壤的氮元素含量。     

浸渍粘合法制备棉丝非织造地膜及其性能表征

 通过将棉、丝纤维按不同的配比进行混合,经过梳理、成网、水刺工艺固结定型,然后在4%的明胶溶液中进行浸渍处理,实现可降解棉质非织造地膜的制备。测试该产品的强力、透水性、透湿性、降解性,采用ESEM、红外光谱、降解率等方法进行理化性能表征,分析其降解前后的性能差异。结果表明:该非织造地膜与常规农用地膜相比具有较好的物理性能、降解性,且降解后的土壤全氮含量增加较大,有利于土壤增肥。     

无铬鞣废革屑胶原提取物与PBAT共混成膜性能

利用稀酸法分别从沸石、TWS鞣废革屑中提取胶原,以提取率、特性粘数等为指标优化提取工艺,对纯化后的胶原水解物进行表征。随后选取TWS鞣废革屑提取的胶原水解物（C-TWS）与聚己二酸对苯二甲酸丁二醇酯（PBAT）共混成膜,探究二者的成膜性能。结果表明：两种胶原水解物均含有17种氨基酸,元素组成以C、N、O为主,矿物盐含量低,是优质的生物可降解蛋白基材。PBAT/C-TWS共混过程为简单的物理共混,C-TWS组分含量的增大使复合膜的水蒸气透过量提高43.05%～182.5%。C-TWS组分含量为30%时,薄膜的最大热降解温度由405.4℃降低至386.5℃,所有比例共混膜都具有良好的透光率,共混体系中C-TWS组分含量小于50%时具有较好的相容性。     

新型复合体系液体地膜的性能研究

采用无毒的植物残渣为主要原料合成了一种新型复合体系液体地膜.对其光老化性能、最大稀释倍数及试验田土壤中水分分布等多项性能的测试结果表明:该新型液体地膜具有良好的长期和低温储存稳定性;老化时间为50 d,完全可以满足作物生长周期的要求;最大稀释倍数在保证抑蒸率满足使用要求的情况下由普通沥青体系液体地膜的7倍～8倍提高至20倍;覆盖的土壤在0 cm～40 cm的水分分布比较均匀,且土壤的表面温度比用塑料地膜高2 ℃～3 ℃.     

邻苯二甲酸二丁酯降解菌株的筛选鉴定及其降解特性研究

从四川省雅安市使用过地膜的蔬菜田地的土壤中筛选得到一株以邻苯二甲酸二丁酯(DBP)为唯一碳源和能源生长的高效降解菌株JF,经形态学、生理生化特征和16S rDNA序列分析,该菌株被鉴定为枯草芽孢杆菌(Bacillus subtilis)。在LB培养基的动力学研究表明,菌株JF降解邻苯二甲酸二丁酯的过程满足一级动力学方程模型,在测试的底物(DBP)浓度、温度、pH范围内,DBP的半衰期为3.11~6.98 h,且该反应的速率受底物浓度和温度的影响较大,受pH值影响不大。菌株JF可降解DBP及其中间产物邻苯二甲酸,此外,菌株JF在72 h内对200μg/mL的邻苯二甲酸二(2-乙基己)酯(DEHP)、邻苯二甲酸二辛酯(DOP)和邻苯二甲酸丁苄酯(BBP)降解率为90.10%、79.10%和76.30%。该研究为消除或减少环境、农产品中邻苯二甲酸酯残留提供了理论依据。     

Novel photodegradable low-density polyethylene-TiO2 nanocomposite film

A new type of photodegradable low-density polyethylene (LDPE)-TiO2 nanocomposite film was prepared by a melt blending technique. The photocatalytic degradation of the LDPE-TiO2 nanocomposites was investigated. The as-prepared films were characterized by scanning electron microscopy (SEM), high-temperature gel permeation chromatography (HT-GPC), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and the photoinduced weight loss. The results show that the LDPE-TiO2 nanocomposite films could be efficiently degraded under UV or sunlight illumination. The weight loss rate of the composite film reached 68.38%, the average molecular weight (Mw) of the composite film decreased 94.56%, and the number of average molecular weight (Mn) decreased 93.75% after UV-light irradiation for 400 h. FT-IR and XPS analysis indicated that the LDPE was oxidized during UV-light irradiation. The photocatalytic degradation mechanism of the films is briefly discussed.     

氮素水平对烤烟根系形态、结构及其氮素积累的影响

  目的  探究不同氮素水平对烟株根系发育及地上部氮素积累与分配的影响。  方法  试验设置3个氮素水平: HNL(N 8 g/株)、MNL(N 6 g/株)、LNL(N 4 g/株), 分析不同时期烟株根系结构、生理指标、空间分布及其地上部干物质与氮素积累变化情况, 与氮素利用差异。  结果  与HNL相比, LNL显著提高了根系活力与活跃吸收面积, 不定根数量增加了15.2条, 一级侧根与不定根的平均长度提高了10 cm、6.6 cm, 不定根与一级侧根平均直径与干重降低。降低施氮水平, 根系20~50 cm土层的根长密度与根干重增加, 现蕾期LNL根干重占比较HNL提高了8.32 g。LNL抑制了烤烟地上部生长, HNL成熟期地上部干物质积累量与氮素积累量显著增加, 提高了29.30%、49.06%, 但与MNL差异不显著。  结论  烟株氮素少量缺乏, 烟株通过调节根系形态结构, 增加不定根数量, 提高了根系氮素吸收能力, 对烟株地上部发育影响不显著, 生产上可以通过改变施肥方式与施肥时间, 达到降低氮肥使用量的目的。      

淀粉复合膜的堆肥降解性能研究

目的 研究淀粉三层复合膜的降解过程及降解周期。方法 通过测定淀粉复合膜在受控堆肥条件下其排放的二氧化碳量来确定其最终需氧生物分解能力及其崩解程度, 通过测定失重率、扫描电镜、X-射线衍射、红外光谱等方法观察降解前后淀粉复合膜的形貌、结晶度、化学结构等变化。结果 淀粉复合膜在受控堆肥条件下表现出良好的生物降解性, 56 d后生物分解率可达47.23%, 与失重率相一致。淀粉复合膜在土埋降解的56 d内, 外观和微观形貌都发生了显著变化, 结晶度降低, 晶体结构被破坏, 降解前后没有产生新的基团, 只是大分子分解为小分子的过程, 降解周期为42 d。结论 淀粉复合膜在受控堆肥条件下具有良好的生物降解性。     

Impact of a novel spray-chilling system on surface microflora, water activity and weight loss during beef carcass chilling

Commercially slaughtered and dressed beef carcass sides (n=30) were followed through a standard commercial chill unit fitted with a new "Jasca" air humidification system adjusted to provide intermittent water spraying of carcass sides (spray cycle 2 min on, 1 min off) for 15 h. Immediately after dressing, and after 24h in the chill unit, the surface water activity, and the weight of each side was measured, and 5 cm2 samples were recovered from four locations, i.e. rump, flank, brisket and neck on the surface of each side. These samples, and similar samples from control sides (n=30) processed in a standard commercial chill unit, were subjected to microbiological examination by direct and resuscitation counts on plate count agar (PCA), MacConkey agar (MAC) and violet red bile glucose agar (VRBGA). No significant differences were observed between bacterial numbers on test and control samples on each of the above agars, at each sample point/occasion. Comparison of direct and resuscitation counts suggested the presence of substantial numbers of injured cells, at both stages (pre- and post-chill), on test and control sides. After 24 h in chill units, test sides exhibited an average weight loss of 1.36% (+/-0.36%), which is significantly less (P<0.001) than the average weight loss (1.55%+/-0.24%) from control sides. These results suggest that the Jasca spray-chilling system can limit carcass shrinkage (on average by 0.19%) without significantly increasing the surface populations of selected bacterial groups.     

植保无人机在甘蔗害虫防治上的应用效果

由于甘蔗生长后期植株高大,存在手工操作难、作业效率低、喷药风险大的问题,为探索植保无人机在甘蔗害虫防治上的应用效果,2018年在云南陇川进行了试验示范。结果表明,在甘蔗根施农药防治的基础上,在蓟马大发生期,选用植保无人机喷33%氯氟·吡虫啉SC 240 mL/hm2对甘蔗蓟马的防治效果较好,与防治前相比,相对防效为83.5%,与根施70%噻虫嗪ZF 240 mL/hm2相比,相对防效为67.6%;在甘蔗螟虫蛀茎危害初期,选用植保无人机喷40%氯虫·噻虫嗪WG 240 g/hm2对甘蔗螟虫的防治效果显著,与根施4%吡虫·毒死蜱GR 30 kg/hm2相比,对螟害株率的相对防效91.2%,对螟害节率的相对防效为96.1%,与根施2%吡虫啉GR+0.4%氯虫苯甲酰胺GR 30 kg/hm2+30 kg/hm2相比,对螟害株率的相对防效52.0%,对螟害节率的相对防效53.8%。说明植保无人机进行甘蔗害虫防治上具有作业效率高、对甘蔗安全和防效好的优势。     

Effect of relative humidity on the store stability of spray-dried beta-carotene nanoemulsions

In order to overcome the limitations of liquid-base emulsion system, beta-carotene nanoemulsions stabilized by modified starch were spray-dried to powders after the emulsification process. The powders showed a good dissolution in water and the reconstituted emulsions had similar particle sizes with the fresh nanoemulsions. A 30 days storage test was carried out to investigate the effect of relative humility (RH) on the storage stability of beta-carotene powders at 25.0 °C. The beta-carotene degradation profiles over time were found to fit well with a Weibull model and also closely related to the film property of the matrix, moisture sorption property and glass transition temperature of the powder. The results showed that modified starches with lower film oxygen permeability had a higher retention of beta-carotene during storage. The glass transition temperature of powder in different RH also affected the rate of beta-carotene degradation. Overall these results provide useful information for choosing wall materials and storage conditions to protect nutraceuticals in delivery systems.     

大豆7S 球蛋白酶解产物在猪肉肠中的应用

本研究以大豆为原料提取7S 球蛋白,并对其进行酶法水解。以质构特性、凝胶强度、肉肠得率为评价指标,比较添加不同水解度和不同添加量的7S 酶解蛋白对猪肉肠品质的影响。采用二因素三水平正交试验,确定肉肠专用比,蛋白的最佳工艺参数为7S 球蛋白水解度为11%、添加量为1.5%。     

Effects of chilling rate and spray-chilling on weight loss and tenderness in beef strip loin steaks

We evaluated the effects of chilling rate and the use of a spray-chilling system on the weight loss by evaporation on carcasses. We also evaluated the effects on meat purge in vacuum package, cooking losses, and on parameters related to the tenderness of strip loin steaks (M. longissimus lumborum). Forty non-castrated males of approximately 12 months old, finished in feed-lot were harvested in 16 Montana cattle (a composite breed), and 24 Simmental × Nellore crossbred cattle. After bleeding, the bodies were electrically stimulated and assigned to one of the four treatments: conventional air-chilling (CAC), conventional spray-chilling (CSC), slow air-chilling (SAC), and slow spray-chilling (SSC). Strip loin steaks (M. longissimus lumborum) of approximately 2.5 cm thick were removed, vacuum packed and aged for 7, 14, 30 or 60 days. Samples were analyzed for sarcomere length, myofibrillar fragmentation index, Warner–Bratzler shear force, and weight losses by purge and cooking. Spraying was efficient in reducing weight loss by evaporation (P < 0.05). Effects of treatments and aging period on purge losses were observed, where samples from sprayed carcasses or aged cuts showed higher losses. Cooking losses were not affected either by spraying or aging. The slow chilling, with or without spraying, was more efficient in producing strip loin steaks with lower average shear force and longer sarcomere. The myofibrillar fragmentation index increased with aging time, but was not affected by carcasses spraying.     

热塑性聚氨酯熔喷非织造材料制备与性能

为改善传统熔喷非织造材料强度低、弹性回复性差的问题,以热塑性聚氨酯(TPU)为原料制备了一种新型弹性熔喷非织造材料。研究了TPU的热性能及流变性能,分析了制备工艺参数对TPU熔喷非织造材料形貌、力学性能、透气性能和水接触角的影响。结果表明:数均分子量为33 767 g/mol、分子量分布指数为2.19、熔点为159.4 ℃的TPU原料,在230 ℃时流变性能良好,适合进行熔喷纺丝;当纤维平均直径为10.27 μm、纤维网平均孔径为145 μm时,制备的TPU熔喷非织造材料的纵、横向断裂强度分别为52和49 N/(5 cm),纵、横向断裂伸长率分别为424%和459%,50%伸长回复率为97%,透气率为580 L/(m²·s),水接触角为110.3°,呈现明显的拒水特性。