High water content silk protein-based hydrogels with tunable elasticity fabricated via a Ru(II) mediated photochemical cross-linking method

Silk is very promising in the field of biomaterials as a natural biomacromolecule. Silk protein can be made into various forms of materials, including hydrogels. However, silk protein-based hydrogels have not attracted much attention due to its weak mechanical properties. Here, we report high water content silk protein-based hydrogels with tunable elasticity which were fabricated through Ru(II) mediated photochemically cross-linking tyrosine residues in regenerated silk protein. The regenerated silk protein was characterized by Fourier transform infrared spectroscopy (FTIR). The gelation kinetics of the silk protein was studied by rheology measurements. The compressive mechanical properties of the silk protein-based hydrogels was investigated using compressive tests and dynamic mechanical analysis (DMA). Compressive modulus of the hydrogels reached 349±64 MPa at 15 % strain. The fabricated silk protein-based hydrogels were also characterized by Scanning electron microscopy (SEM), revealing an interconnected porous network structure, typical of hydrogels, with an average pore size of approximately 130 μm. Finally, biocompatibility of the silk protein-based hydrogels was demonstrated through cell culture studies using a human fibroblast cell line, HFL1. The reported silk protein-based hydrogels represent a promising candidate for biomaterial applications.     

六个猕猴桃品种在六盘水市的品比试验

以国内外较优6个猕猴桃品种为试材,利用引种技术进行品种的引进及筛选,综合评价各品种的物候期、适应性、果实品质等指标,以优化和调整六盘水猕猴桃品种结构,探明并确定贵州猕猴桃主产区六盘水市适应性较好的品种。结果表明:根据各品种的表现和"合理-满意度"分析,在六盘水表现较好的品种有"红阳",成熟期为8月中下旬,总糖含量为11.90%,口味香甜,果肉为红色,667m~2产量742.8kg,"金艳"成熟期为9月,667m~2产量1 018.6kg、单果质量118.43g、香味浓郁、果肉金黄色,"贵长"成熟期较晚,667m~2产量为1 401.7kg,香味较浓、果肉翠绿色;表现不好的品种有"西选2号""楚红",这2个品种产量均较低,果实口感一般;表现相对较好的品种有‘Hort 16A’口感较好,但抗病性较弱,"和平2号"单果质量156.80g,但667m~2产量仅有953.1kg,"海沃德"667m~2产量仅有703.6kg,表现不稳定。"红阳""金艳""贵长"在六盘水地区表现良好,适宜推广种植。     

不同产地‘南果梨’贮藏中糖酸含量变化研究

作者对鞍山坡地和沈阳坡地、平地栽培的‘南果梨’,测定常温贮藏下果实可滴定酸和可溶性固形物的含量,同时比较常温和4℃下1-MCP处理的果实可滴定酸和可溶性固形物的含量。结果表明,原产地鞍山坡地‘南果梨’果实在常温贮藏下的可滴定酸和可溶性固形物含量高于沈阳坡地的,沈阳坡地的高于平地的;常温1-MCP处理能更好地延缓果实可滴定酸分解和可溶性固形物的积累,使‘南果梨’在采后室温贮藏过程中保持良好的风味品质。     

起垄沟播和常规平播下滴灌棉田土壤水盐的运移

为明确滴灌条件下植棉方式对土壤水盐运移的影响,采用田间调查与室内分析相结合的方法,在滨海重度盐碱地开展了起垄沟播和常规平播植棉方式下的水盐运移试验,调查了滴灌前后两种植棉方式不同点位及不同土壤深度的土壤水分、盐分和土壤溶液电导率等指标,分析不同植棉方式土壤水分、盐分和土壤溶液电导率的时空分布特征。结果表明：滴灌条件下起垄沟播的水分入渗深度和盐分淋洗深度均明显大于常规平播植棉方式,起垄沟播植棉膜下(0~20 cm)土壤溶液电导率明显低于常规平播植棉;滴灌对两种种植方式膜外土壤水分和盐分运移未产生明显影响。起垄沟播联合滴灌技术更有利于为棉花生长的水盐环境。研究结果可为盐碱地植棉提供理论参考和实践依据。     

Effect of apple cultivars and storage periods on the virulence of Neofabraea spp.

Bull’s eye rot is a typical quiescent postharvest apple disease in major fruit-growing areas. The susceptibility of different apple cultivars to Neofabraea spp. (N. vagabunda and N. malicorticis) was assessed, with Granny Smith showing the most resistance and Cripps Pink the most susceptibility. To assess the factors involved in conidial germination, Neofabraea spp. were grown on crude protein extracts (CPEs) collected from apple fruits at different storage periods. Fungal germ tube growth rate and pathogenic enzyme (cellulase and xylanase) activity were assessed. Results showed that CPEs collected after 2 and 4 months of storage progressively stimulated conidial germination and germ tube elongation, while a lesser effect was observed from CPEs after 1 month of storage. Xylanase proved to be the main degrading enzyme secreted by all the isolates, while cellulase was produced only by N. vagabunda isolates. Overall, the isolate ID02 was the most virulent, based on more rapid germ tube elongation and greater activity of the lytic enzymes.     

黏虫蛹性别的快速鉴别方法

根据黏虫Mythimna separata(Walker)蛹生殖孔的位置、腹部腹节的外部形态学特征、生殖孔(产卵孔)至排泄孔之间的距离,快速、准确鉴别黏虫蛹性别。雌蛹第8腹节腹面中央的生殖孔与第9腹节的产卵孔连接形成一纵裂缝,裂缝两侧平坦,无突起。生殖孔下端与第9腹节的前缘连接、产卵孔下端与第10腹节的前缘连接,形成2个明显的"人"字纹。雄蛹第8腹节无纵裂缝,在第9腹节腹面中央的生殖孔呈现的纵裂缝连接第10腹节,裂缝两边各有一个半圆形瘤状突起。雌雄蛹排泄孔均在第10腹节腹面,雌蛹产卵孔下端至排泄孔上端之间的距离为(400.85±151.10)μm,雄蛹生殖孔下端至排泄孔上端之间的距离为(178.21±93.59)μm,约为雌蛹相应距离的一半。采用该方法观察的270头羽化蛹的性别鉴别准确率100%。该方法对于快速鉴别黏虫蛹的性别、开展黏虫相关的生物学研究以及预测预报等具有重要的参考价值。     

蔬菜中13种有机磷农药基质效应研究

有机磷农药在农业生产中广泛应用,用气相色谱法进行农药残留检测容易产生基质效应,影响分析结果的可靠性,为研究用气相色谱法进行农残检测过程中有机磷农药在不同蔬菜中的基质效应,选取瓜类、茄果类、叶菜类3类常见蔬菜和13种有机磷农药进行研究,对影响基质效应的因素采取不同变量法进行分析,得出结论:有机磷农药在叶菜类蔬菜中基质效应最大;含有P=O键农药基质效应更强;基质含量越多基质效应越强,并对在检测如何减少基质效应给出了建议.     

广西甘蔗地冬季黏虫发生调查初报

于2014—2018年冬季,在广西桂南地区、桂中、桂西和桂东南地区选择不同类型甘蔗地,调查黏虫发生及为害情况。结果表明,新植蔗和收割后焚烧蔗叶的宿根蔗地极少发现黏虫,而收割后蔗叶(直接或粉碎)还田的宿根蔗地发现有不同龄期的幼虫为害,老蔗地亦发现老熟幼虫或蛹,但虫口密度低。数据显示,广西桂南地区冬季甘蔗地黏虫虫口密度最大。其中,2017年南宁市武鸣区虫口密度最高,达8.9头/m^2,其次是桂东南地区,桂中地区和桂西地区极少或未发现黏虫。     

4YZP-4X自走式玉米收获机的设计研究

我国玉米收获机普遍存在可靠性低、适应性差、可操控性低及自动化水平落后等问题,不能满足玉米收获季节性强、劳动强度高、作业量大等实际作业需求。液压系统具有布置紧凑、操作方便、故障率低等优点,非常适合应用于结构形态多变、工作条件恶劣的农业机械。为此,结合目前玉米生产现状和现有技术装备,设计了一种静液压驱动自走式玉米收获机,可一次性完成摘穗、输送、剥皮和秸秆切碎还田等作业。田间性能试验结果表明:该机操控简单、可靠性高,主要性能指标均达到或优于国家标准。     

探析发动机气缸套磨损的原因及预防措施

气缸套作为发动机气缸的重要组成部分,在工作过程中的快速磨损,将会影响到发动机的正常寿命.文章阐述了引起气缸套磨损的三种情况:结构原因、使用不当、维修操作不当.在此基础上,提出了预防减少气缸套磨损的措施:正确起动发动机;正确选用润滑油;加强滤清器的保养;保持发动机正常工作温度.