果蔬气调贮藏保鲜技术探讨

近年来，世界工业发达国家的果蔬贮藏保鲜技术发展很快，其中采用降温、降氧、控制二氧化碳及乙烯含量的气调保鲜是世界上果蔬贮藏的最先进方法。本文介绍了气调贮藏保鲜的原理及方法、果蔬气调贮藏保鲜的工艺条件及气调库的气密性要求和施工技术。     

果蔬采后气调保鲜技术

果蔬采后气调保鲜技术,是指果蔬采摘后,利用气调库或其他气调贮藏方式,通过控制或自发调节贮藏环境的温度、相对湿度和气体环境的方式,抑制果蔬呼吸作用,减缓衰老进程,保持果蔬新鲜状态同时能保证其正常后熟的技术。     

开展氮气保鲜贮藏 推进“绿色食品”行动

气调保鲜贮藏果蔬 ,70年代在世界得到迅速发展 ,主要用于苹果保鲜。我国有些地方的氧气厂站也利用放空氮气建立起氮气气调库 ,如河南周口地区气体总厂已建 10 0吨、 5 0 0吨气调库各一座 ,自 1998年开展新鲜水果、蒜苔等气调保鲜 ,以及干制果蔬气调贮藏 ,都取得良好效果与可观效益。《深冷技术》曾作过一些报道。中国农业科学院柑桔研究所 (重庆 )于 1986年开始进行“柑桔氮气保鲜贮藏技术”研究 ,经过十年的努力 ,得出所有水果品种充氮气调贮藏之后 ,都保持鲜果风味 ,香气浓郁 ,感官品尝 ,处理果与对照果的风味和香气差异明显。 1992年 ,柑…     

吸附法脱除果蔬气调保鲜库气氛中的乙烯

目前气调库保鲜是果蔬保鲜方法中最先进的保鲜方法之一。气调保鲜库运行的重要环节是控制气调库内气体组成和含量。本课题研究的是用变压吸附法调节控制气调库中的气体组成和含量。通过对本课题的研究提供了吸附脱除QH4的最佳吸附剂和工艺流程,使气调库保鲜气体中的QH4降至≤10ppm,再将净化气返回气调库循环使用,这样可以降低果蔬保鲜的成本,具有广阔的市场前景。     

果蔬气调贮藏研究现状及展望

果蔬含水量高,鲜嫩易腐,给贮藏带来了极大的困难。分析了影响新鲜果蔬保鲜的主要因素,包括温度、湿度、气体成分以及微生物;综述了国内外气调贮藏保鲜技术的发展概况和研究现状;分析了果蔬气调贮藏当前面临的主要技术问题,并提出了解决对策。果蔬气调贮藏具有广阔的发展前景。     

果蔬气调库贮藏中温湿度控制及气密性措施

近几年果蔬气调库发展迅速。气调库与一般高温库温度、湿度控制要求不同 ,温湿度控制不但关系到贮藏食品的品质 ,还会影响到气调库中设定的气体成分。本文详细地讨论了气调贮藏中温度、湿度的控制要求、控制方式 ,以及实现气调库气密性的措施。     

组合式气调冷库

介绍了组合式气调冷藏库对果蔬与食物的保鲜机制,叙述了气调库的主要评价指标:库体气密性,库体传热系数,隔热库板性能试验,隔热板材料与结构,气调库的主要性能指标;还介绍了国外气调动态。     

果蔬气调库贮藏中温温度控制及气密性措施

近几年果蔬气调库发展迅速,气调库与一般高温温度、湿度控制要求不同,湿湿度控制不但关系到贮藏食品的品质,还会影响到气调库中设定的气体成分,本文详细地讨论了气调贮藏中温度,湿度的控制要求,控制方式,以及实现气调库气密性的措施。     

西部地区果蔬气调库建设方面的一些建议

中国的西部盛产果蔬，在西部大开发中，特别在我国加入WTO后，应大力发展西部果蔬产业，这可以在拉动地区经济发展的同时、促使中国的高档果蔬走向国际市场。气调库的推广使用为这一产业的发展提供了条件。但如何保证果蔬贮藏质量、节约能源消耗值得我们进一步深入研究。本文结合西部地区的气候特点和气调技术发展现状提出西部地区果蔬气调库在设计、施工、运行管理方面应采取的措施，为西部地区果蔬气调贮藏产业的发展提供参考。     

《气调保鲜库综述》

一座完整的气调库一般是由库体结构、气调系统、制冷系统、加湿系统、中央测控管理系统等构成。1VSA气调系统,对一个气调库来说,气调系统是气调库的核心,主要包括制氮设备、二氧化碳脱除设备、乙烯脱除设备（视所贮藏果蔬要求而定）、加湿设备、气调门、气调袋、气体检测设备及阀门管线等组成。其中制氮设备利用率最高,所以显得更为重要。     

一种基于CSMA/CA的水声网络功率控制MAC协议

水声通信网络在资源勘探、灾害预报、环境监测等方面有广阔的应用前景。由于水声通信环境传播延迟高、带宽窄,TDMA、FDMA等多址接入方式的应用受到了限制,因此在水声网络中一般采用随机接入的方式。CSMA／CA是一种得到广泛应用的多址接入协议。在CSMA／CA协议的基础上,设计了一种适用于水声网络的功率控制MAC协议-PC-CSMA／CA协议。PC-CSMA／CA协议利用CSMA／CA进行RTS／CTS预约的特点,进行数据包传输的自适应功率调整,在不影响CSMA／CA协议的性能的同时节约了能量。仿真结果表明：改进后的协议大大减少了能量消耗,且不影响网络的吞吐量。     

均相与非均相法制备醋酸纤维素的性质比较

以DMAc/LiCl为溶剂在均相体系中不加任何催化剂合成了醋酸纤维素(CA),运用化学滴定、1H-NMR、X射线衍射、DSC等手段对均相与非均相合成产物的结构及性质进行了对比.结果表明,在总取代度相同条件下,均相法制备的CA中乙酰基在葡萄糖环上C-2,C-3,C-6的分布更均匀;与纤维素相比,非均相法制备的CA结晶度降低为40%,而均相法制备的CA完全变为无定型态;均相法制备的CA的Tg比非均相法有明显下降;均相法制备CA溶液的透光率比非均相法制备CA的高.     

稀溶液黏度法研究醋酸纤维素/聚乙烯吡咯烷酮共混物的相容性

以冰醋酸为共溶剂,利用乌氏黏度计在25℃研究了醋酸纤维素(CA)、聚乙烯吡咯烷酮(PVP)以及不同组成的CA/PVP共混物(CA的质量分数分别为0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9)的粘性行为。基于稀溶液黏度法确定的4种相容性判据(Δb,Δb’、Δ[η]m和α)探讨CA/PVP共混体系的相容性。实验结果表明,当醋酸纤维素在CA/PVP共混体系中的质量分数低于0.12或者在0.8～0.91范围内时,CA与PVP是相容的,其余的组成体系都是不相容的。因此,CA/PVP共混体系是部分相容体系。     

肉桂醛复合材料的制备工艺及其应用研究现状

目的为肉桂醛(CA)复合材料的创新开发及其应用提供理论依据。方法综述国内外CA复合材料的主要复合工艺、应用领域和具体效果,并对存在的问题进行分析,同时对CA复合材料的发展趋势进行展望。结果 CA复合材料因其优良的抑菌抗氧化作用主要被应用在食品包装和医疗方面,更多地被应用在食品保鲜包装中,缺乏针对应用在其他方面的研究。结论国内外对CA复合材料的研究刚起步不久,工艺和应用都还比较单一,研究新型的、具有更多功能的CA复合材料以及开发其在其他领域方面的应用将是未来CA复合材料的发展趋势。     

Channel coordination with quantity discounts and/or cooperative advertising

We assess the interactive effects of two commonly used channel coordination mechanisms (quantity discounts (QDs) and cooperative advertising (CA)). We use a game-theoretic model and solve four non-cooperative games. In the first game, neither QDs nor CA is implemented. Cooperative advertising alone is offered in the second game, while quantity discounts alone are offered in the third game. In the fourth game, both QDs and CA are implemented. We obtain analytical solutions and compare equilibrium results across games to assess the effectiveness of CA (QDs) when implemented alone or jointly with QDs (CA). The main findings suggest that the profitability of each of these mechanisms is affected by whether the other is implemented or not in the channel. For example, while CA benefits the manufacturer when implemented alone, it can increase or decrease the manufacturer’s profit when added to QDs. Looking at which coordination mechanism is most effective when used alone, we find that both the manufacturer and the supply chain prefer QDs to CA. Finally, the retailer may not benefit from either one or both of these coordination mechanisms, especially if marketing efforts are not highly effective.     

Synthesis of a silver nanoparticle network induced by a micro-phase separation

Fabrication of a silver nanoparticles (AgNPs) network by only acetone (Ace) vaporization from AgNPs/cellulose acetate (CA)/Ace/1-octanol (Oct) suspension was proposed. When Ace vaporizes from CA/Ace/Oct ternary reaction system, a micro-phase separation occurs into polar phase (CA/Ace) and non-polar phase (Oct), then CA molecules deposit as three-dimensional network. Dispersed AgNPs in the ternary system gather each other along with the flow of CA network formation and AgNPs aggregates are taken into the CA network. In Ace-rich system, CA network density increased and surface of CA strut became smooth because of well dissolved of CA. AgNPs dispersibility also increased, however, lack of continuity on AgNPs network was observed. When AgNPs amount simply increased, CA network disappeared and large AgNPs aggregates remained on CA bulk film. On the other hand, with sum volume of AgNPs/CA kept constant, continuous AgNPs network was successfully formed according to CA dense network.     

Cellular automata on irregular tessellations

To this day, most articles on cellular automata (CA) employ regular tessellations of ? ⁿ , notwithstanding this kind of tessellation suffers from a few serious drawbacks limiting the appraisal of regular CA as full-fledged modelling tools. In this article, we propose an extension to the classical CA paradigm, by allowing irregular tessellations of ? ⁿ , which, in essence, encloses the regular tessellations as a special case. After a short review on the major shortcomings of CA on regular tessellations, we establish a definition for CA on irregular tessellations of ? ⁿ that is followed by a profound elaboration of its constituents. In addition, we propose a graph representation that is applicable to an important family of irregular CA, and, in accordance with the framework developed for CA on regular tessellations, we present an enumeration scheme for the k-state, θ-sum irregular (outer-)totalistic CA. Illustrative examples conclude this article.     

Microstructures and properties evolution of Al-Zn-Mg-Cu alloy under electrical pulse assisted creep aging

Creep aging (CA) is a promising forming technology for integral panels with complex structures. However, how to balance excellent corrosion resistance and strength is still a challenge for CA parts. By synchronously applying electrical pulse (300 Hz, 15 A/mm²) in the middle of steady-state CA of Al-Zn-Mg-Cu alloy, the electrically assisted CA (ECA) is proposed to induce retrogression rapidly for realizing a three-step aging (retrogression and re-aging, RRA) in CA to tailor the needed properties balance. It is compared with conventional CA with one-step aging (peak aging, T6 or over aging, T7), two-step aging (over aging, T73) and RRA in hardness, intergranular corrosion and microstructures. For the ECA of pre-aging and re-aging for 20 h plus electropulsing for 10 min, the hardness is 10.5%, 20.5% and 18.9% higher than those of CA with T6, T7 and T73 processes, respectively, while the corrosion resistance is higher than T6 process and lower than T7 and T73 processes. Although the hardness and corrosion resistance are comparable to those of the CA with the RRA process, ECA takes one hour less due to the accelerated effect of the electropulsing and is not limited by the thick plates. The improved comprehensive performance of the ECA sample is due to both fine intragranular precipitates η′ and large discontinuous grain boundary precipitates η.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00404-2     

钢筋锈蚀对全珊瑚海水钢筋/混凝土柱大偏心受压性能的影响

通过对不同混凝土强度等级、不同种类钢筋的全珊瑚海水钢筋/混凝土柱（CA/CC）进行大偏心受压性能试验,研究了CA/CC的破坏形态、变形和承载力,建立了荷载-位移、荷载-应变等关系,探讨了CA/CC大偏心受压极限承载力（N_u）的计算模型。结果表明:CA/CC的受力破坏机制和形态与普通骨料钢筋/混凝土柱（OA/CC）基本相似。随着混凝土强度等级的提高,CA/CC纵向受拉钢筋应变开始突变所对应的荷载逐渐增大。在加载过程中,有机新涂层钢筋与珊瑚/混凝土（CA/C）之间产生较大的滑移,使在相同混凝土强度下,普钢钢筋CA/CC的N_u比有机新涂层钢筋CA/CC的N_u大约高7.1%~20.8%。建议在CA/C结构中采用有机新涂层钢筋,能有效的抑制钢筋发生锈蚀,从而延长CA/C结构的有效服役寿命。综合考虑钢筋锈蚀和涂层钢筋滑移的影响,提出了适用于满足高强、高耐久性要求的CA/CC大偏心受压N_u计算模型。      

Cellulose acetate electrospun fiber mats for controlled release of silymarin

In this research, the silymarin-loaded electrospun cellulose acetate (CA) fibers were prepared which containing silymarin in various amounts (i.e., 2.5-20 wt.% based on the weight of CA powder). Incorporation of silymarin in the neat CA solution did not affect the morphology of the resulting fibers, as both the neat and the silymarin-loaded CA fibers were smooth. The average diameters of silymarin-loaded CA fiber ranged between 550-900 nm. No presence of the silymarin aggregates of any kind was observed on the surfaces of these fibers, suggesting that the silymarin was encapsulated well within the fibers. These results were confirmed by lowering the glass transition temperature and the melting temperature of the silymarin-loaded electrospun CA fibers which is determined by DSC technique. The release characteristic of silymarin from the silymarin-loaded CA fiber mats was investigated by the total immersion in the solution of 1/1 phosphate buffer/methanol medium pH 7.4 at 37 degrees C. The silymarin release from the silymarin-loaded electrospun CA fiber mat is monotonously increased to reach the maximum value at 480 min. The maximum amount of silymarin released from these materials increases with the increasing of initial silymarin loading in the spinning CA solutions. Since no aggregation of silymarin was found on the surface of the silymarin-loaded fibers, the release of the silymarin from fiber mats was mainly by the diffusion.