Impact of Low-temperature Storage on Volatile Flavor Compounds in Prepared Pork Products

[Objectives]This study was conducted to explore the dynamic changes of volatile flavor compounds in prepared pork during storage at different low-temperature conditions.[Methods]Prepared pork was stored at 4,-4 and-18℃.The volatile flavor compounds of prepared pork were determined by solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)at days 0,7,14,21 and 28,and relative odor activity value(OAV),principal component analysis(PCA)and cluster analysis(CA)were combined to analyze changes in volatile flavor compounds of prepared pork during storage.[Results]The total number of volatile flavor compounds gradually decreased with the prolongation of the storage period,and OAV analysis identified 22 key flavor compounds(OAV≥1).The results of PCA and CA showed that 2-methyl-1-butanol,1-octen-3-ol,linalool,cineole,hexanal and nonanal were the main key flavor components,and the degree of flavor degradation was low under both superchilling and freezing conditions.After 28 days of storage,the alcohol content in the chilling group was significantly higher than other two groups,and the overall content of volatile flavor compounds was also significantly higher than other two groups,indicating that the-4℃chilling storage was more favorable for maintaining the overall flavor of prepared pork.[Conclusions]This study provides a theoretical basis for finding a better storage method for prepared meat products.

Hybrid hard carbon framework derived from polystyrene bearing distinct molecular crosslinking for enhanced sodium storage

Exploiting high-performance yet low-cost hard carbon anodes is crucial to advancing the state-of-the-art sodium-ion batteries.However,the achievement of superior initial Coulombic efficiency(ICE)and high Na-storage capacity via low-temperature carbonization remains challenging due to the presence of tremendous defects with few closed pores.Here,a facile hybrid carbon framework design is proposed from the polystyrene precursor bearing distinct molecular bridges at a low pyrolysis temperature of 800℃ via in situ fusion and embedding strategy.This is realized by integrating triazine-and carbonylcrosslinked polystyrene nanospheres during carbonization.The triazine crosslinking allows in situ fusion of spheres into layered carbon with low defects and abundant closed pores,which serves as a matrix for embedding the well-retained carbon spheres with nanopores/defects derived from carbonyl crosslinking.Therefore,the hybrid hard carbon with intimate interface showcases synergistic Na ions storage behavior,showing an ICE of 70.2%,a high capacity of 279.3 mAh g^(-1),and long-term 500 cycles,superior to carbons from the respective precursor and other reported carbons fabricated under the low carbonization temperature.The present protocol opens new avenues toward low-cost hard carbon anode materials for high-performance sodiumion batteries.

Influence of broken kernels content on soybean quality during storage

Although it is recognized that the post-harvest system is most responsible for the loss of soybean quality,the real impact of this loss is still unknown.Brazilian regulation allows 15%and 30%of broken soybean for group I and group II(quality groups),respectively.However,the industry is not informed about the loss in the quality parameters of soybeans and its impacts during long-term storage.Therefore,the objective was to evaluate the effect of the breakage kernel percentage of soybean stored for 12 months.Content of 15% of breakage kernels did not affect soybean quality.However,content of 30% of breakage kernels affected significantly soybean quality,which was evidenced by the increase of up to 75% in moldy soybeans,72% in acidity,50% in leached solids,27% in electrical conductivity,and the decrease of up to 12% in soluble protein,6.4% in germination and 3.5% in thousand kernel weight after 8 months of storage.Although the legislation establishes a percentage limit,it is recommended to store soybeans with up to 15% breakage kernels.On the contrary,values higher than that can cause a significant reduction in soybean quality,resulting in commercial losses.

Low-Temperature Hydrogen Storage Alloy and Its Application in Ni-MH Battery

Rare earth compositions, La, Ce and Pr in Mm(NiCoMnAl)(5) hydrogen storage alloy, were arranged by uniform design method. The discharge performances and kinetics parameters including capacity, exchange current density, symmetry factor and hydrogen diffusion coefficient of the alloy at -40degreesC, were tested in standard tri-electrode cell. And linear regression method was used to analyze the effect of rare earth compositions on the performances of hydrogen storage alloys. The results show that the capacities of the alloys are positively correlative to the square of Ce content at -40degreesC and under both 0.4 and 0.2C rate. The kinetics parameters and hydrogen diffusion coefficient indicate that the low-temperature performances of the alloys are mainly controlled by hydrogen diffusion process, and the surface electrochemical reaction affects the low-temperature performances to a certain extent. The low-temperature discharge capacities of the battery were also tested. The results show excellent low-temperature performances. The battery delivers 69.6% of its room-temperature capacity at -40degreesC and 0.2C rate, 77.7% at -40degreesC and 0.4C rate, 59.1% at -45degreesC and 0.2C rate.

ZnO-Embedded Expanded Graphite Composite Anodes with Controlled Charge Storage Mechanism Enabling Operation of Lithium-Ion Batteries at Ultra-Low Temperatures

As lithium(Li)-ion batteries expand their applications,operating over a wide temperature range becomes increasingly important.However,the lowtemperature performance of conventional graphite anodes is severely hampered by the poor diffusion kinetics of Li ions(Li^(+)).Here,zinc oxide(ZnO) nanoparticles are incorporated into the expanded graphite to improve Li^(+)diffusion kinetics,resulting in a significant improvement in lowtemperature performance.The ZnO-embedded expanded graphite anodes are investigated with different amounts of ZnO to establish the structurecharge storage mechanism-performance relationship with a focus on lowtemperature applications.Electrochemical analysis reveals that the ZnOembedded expanded graphite anode with nano-sized ZnO maintains a large portion of the diffusion-controlled charge storage mechanism at an ultra-low temperature of-50℃ Due to this significantly enhanced Li^(+)diffusion rate,a full cell with the ZnO-embedded expanded graphite anode and a LiNi_(0.88)Co_(0.09)Al_(0.03)O_(2)cathode delivers high capacities of 176 mAh g^(-1)at20℃ and 86 mAh g^(-1)at-50℃ at a high rate of 1 C.The outstanding low-temperature performance of the composite anode by improving the Li^(+)diffusion kinetics provides important scientific insights into the fundamental design principles of anodes for low-temperature Li-ion battery operation.

Analysis of Grain Storage Security Countermeasures under the New Normal Condition with "Grain Storage Technology" as the Core

Grain storage security is big issue related to national economy and the people＇s livelihood, as well as one of the most important strategic requirements in China. Under the background of grain supply-side structural reform, this paper analyzed the grain storage security countermeasures under the new normal conditions with ＂grain storage technology＂, one of the national grain security strategies of China during the 13th Five-year Plan, as the guiding ideology, from the perspectives of scientific technologies, policy supports, government supports and talent construction, so as to provide supports for the storage enterprises with vulnerable technological links. In addition, the food security issues discussed in this paper could be a helping hand in improving people＇s living quality, enhancing grain storage ecological quality, promoting grain green storage quality security, and be of important and profound strategic significance to enhance the macro-control capability of the government, maintain social stability and people＇s health.

The Current Situation and Development of Grain Storage Technologies and Facilities for Chinese Farmers

In China, the quantity of farmer＇s grain storage covers about 40% of the total grain yield every year. While, the losses of farms＇ grain storage are up to 8%, which is due to the lack of grain storage facility and technology. The losses of farmer＇s grain storage could reach nearly 20 million tons every year. In this paper, the current situation and development of grain storage technology and facility for Chinese farmers were presented. And a series of policy and research work for reducing the losses of farms＇ grain storage was introduced. The large scale farmers are now developing quickly in China, the new storage warehouse and mechanized facility should be developed adaptively. So, the new storage technology and policy to meet the need of large scale farmers were also introduced in this paper.

Grain Hermetic Storage Adoption in Northern Uganda: Awareness, Use, and the Constraints to Technology Adoption

Post-harvest storage losses (PHLs) remain significant in Sub-Saharan Africa (SSA) due to several factors mainly insect pests and molds. Hermetic storage technologies (HSTs) are being promoted to address these storage losses. In Uganda, HSTs were first introduced in 2012. However, its use among farming households remains low today. Data were collected from 306 smallholder farmers from four districts of Northern Uganda using a pre-tested semi-structured questionnaire to understand their knowledge, use, and constraints to the adoption of hermetic storage. A multivariate Logit regression model was used to find the significance of the factors affecting adoption. Results showed low awareness and use of hermetic storage among smallholder farmers. Only 53.3% of the interviewed farmers were aware of the use of hermetic storage for grain storage. The SuperGrain bag was the most known form of hermetic storage (35.3%), followed by the Purdue Improved Crop Storage (PICS) bag (34.9%), metallic silo (15.5%), and plastic silo (14.4%). Hermetic storage use was even lower as only 17.6% of the surveyed farmers were using one or more forms of hermetic storage to store their grains. Insect pest management without chemical insecticides was the main reason (83.1%) for hermetic storage use. About 75.5% of those aware of hermetic storage had received training in the technology. Hermetic storage use in farming households led to improved food availability, household income, and nutrition. Lack of local availability (50.2%), high costs (37.8%), and inadequate knowledge (6.9%) were the main constraints hindering the adoption of hermetic storage in Northern Uganda. The logit regression models showed that only training in hermetic storage significantly (p = 0.002) affected farmers’ decision to adopt hermetic storage. Understanding the factors that constrain the adoption of HSTs could provide policymakers with important information to initiate and design policies and programs aimed at reducing crop storage losses.

Change in Grain-Size Composition of Lignite under Cyclic Freezing-Thawing and Wetting-Drying

The paper presents the change in grain-size composition of lignite under cyclic freezing-thawing (FTC) and wetting-drying (WDC). The article shows that in the spring and autumn periods the lignites can be subjected to repeated freezing-thawing and wetting-drying, which determines the possibility of changing their grain-size composition and structure. Experimental studies in laboratory conditions on the influence of cyclic freezing-thawing (FTC) and wetting-drying (WDC) on the quality indicators of lignites have been carried out, their granulometric (fractional) composition has been studied. Freezing-thawing cycle conditions are as follows (FTC): minimum exposure temperature: -20°C;maximum: +5°C;relative humidity: 30%;number of processing cycles: 3. Wetting-drying cycles are as follows (WDC): drying temperatures are +20, +40, +60, +80°C, drying time 90 minutes, the coals are further subjected to rain (soaking) for a period of water saturation to humidity of 30% - 40% and dry again. The number of wetting-drying cycles is 3 times. The tests have revealed the destructive effects of FTC and WDC on the samples of lower metamorphic grade coal, and the cycles of wet-dry lead to the much higher yield of fine sizes (-6+0;-13+0 mm) than the cycles of freeze-thaw. Furthermore, it is found that the increase in the yield of fines depends on the heating temperature: coal disintegration proceeds more intensively at a higher temperature of drying.

A review of low-temperature heat recovery technologies for industry processes

The amount of low-temperature heat generated in industrial processes is high,but recycling is limited due to low grade and low recycling efficiency,which is one of the reasons for low energy efficiency.It implies that there is a great potential for low-temperature heat recovery and utilization.This article provided a detailed review of recent advances in the development of low-temperature thermal upgrades,power generation,refrigeration,and thermal energy storage.The detailed description will be given from the aspects of system structure improvement,work medium improvement,and thermodynamic and economic performance evaluation.It also pointed out the development bottlenecks and future development trends of various technologies.The low-temperature heat combined utilization technology can recover waste heat in an all-round and effective manner,and has great development prospects.

Effect of electrolyte concentration on low-temperature electrochemical properties of LaNi_5 alloy electrodes at 233 K

The effect of KOH electrolyte concentration on low-temperature electrochemical properties of LaNi5 alloy electrodes at 233 K was studied. The results indicated that the electrolyte concentration had great influence on discharge capacity and discharge voltage plateau of LaNi5 alloy electrode at 233 K, and the highest discharge capacity and discharge voltage plateau were both obtained at 6 mol/L KOH. When the KOH electrolyte concentration changed from 5 to 9 mol/L at 233 K, the high rate discharge ability （HRD） had the same change tendency as the diffusion coefficient, but the exchange current density did not change significantly, which implied that hydrogen diffusion was the control step at low temperature 233 K for discharge process of LaNi5 alloy electrode.

Correlation between the Low-Temperature Photoluminescence Spectra and Photovoltaic Properties of Thin Polycrystalline CdTe Films

A dominant intrinsic luminescence band, which is due to the surface potential barriers of crystalline grains, and an edge doublet, which arises as an LO-phonon repetition of the e-h band, has been revealed in the low-temperature photoluminescence spectra of fine-grained obliquely deposited films. Doping film with In impurity leads to quenching of the doublet band, while further thermal treatment causes activation of the intrinsic band, the half-width and the blue shift of the red edge of which correlates with the maximum value of anomalously high photovoltage generated by the film.

Surface group directed low-temperature synthesis and self-assembly of Al nanostructures for lithium storage

Nanostructured aluminum recently delivers a variety of new applications of the earth-abundant Al resource due to the unique properties,but its controllable synthesis remains very challenging with harsh conditions and spontaneously flammable precursors.Herein,a surface group directed method is developed to efficiently achieve low-temperature synthesis and selfassembly of zero-dimensional(0D)Al nanocrystals over one-dimensional(1D)carbon fibers(Al@CFs)through non-flammable AlCl3 reduction at 70°C.Theoretical calculations unveil surface‒OLi groups of carbon fibers exert efficient binding effect to AlCl3,which guides intimate adsorption and in-situ self-assembly of the generated Al nanocrystals.The distinctive 0D-over-1D Al@CFs provides long 1D conductive networks for electron transfer,ultrafine 0D Al nanocrystals for fast lithiation and excellent buffering effect for volume change,thus exhibiting high structure stability and superior lithium storage performance.This work paves the way for mild and controllable synthesis of Al-based nanomaterials for new high-value applications.

有土斯有粮:高标准农田建设提高了粮食单产吗?

作为“藏粮于地,藏粮于技”战略的重要政策实践,高标准农田建设被期待能够有效实现粮食增产和更好保障国家粮食安全。基于27个省(市、自治区)的面板数据,探索了高标准农田建设对粮食单产的影响及其可能机制。研究发现:(1)高标准农田建设能显著提高粮食单产。替换核心变量、进行非参数估计和考虑内生性的稳健性检验,均证实上述发现可信。(2)机制验证表明,高标准农田建设主要通过提升规模经营、促进技术进步和降低生产风险三大路径来提高粮食单产。(3)异质性分析发现,高标准农田建设对起伏度较小地形、粮食主产区、较发达地区的粮食单产促进效应更大。研究结果表明高标准农田建设确实是夯实粮食安全根基的重要举措,需扎实推进新一轮高标准农田建设工作。

粮仓能源桩系统绿色储粮技术应用研究

简化粮食入库后全周期控温供冷储粮流程,提出满仓主动降温与夏季粮仓热平衡2种供冷方案。通过理论公式计算2种方案下的供冷量需求,并利用有限元模拟软件计算得出能源桩换热量,由此设计可满足上部粮仓供冷需求的能源桩运行方案。结果表明:在1万t储粮规模下,粮仓能源桩储粮技术可满足2种供冷方案下的能源需求,对比谷物冷却机与地源热泵储粮,其初期投入成本更低;对比空调储粮,其初期投入成本增加,但能源桩储粮技术可利用绿色清洁能源,储粮能耗最低。

储粮信息系统弱密码增强多重散列保护方法研究

使用弱密码是计算机信息系统安全的重要漏洞,在粮食储藏信息化应用中亦是如此。单纯的哈希散列加密算法对弱密码存在明显局限性。结合粮库软件系统应用实际,本文提出以哈希散列算法为基础,混入盐值和引入高进制映射等进行增强处理,多次复用散列运算的弱密码保护方法。验证分析表明,方法增加了弱密码的加密值强度,阻断了字典攻击或彩虹表攻击,实现了对弱密码传递和存储的有效保护,且复杂度较低,程序实现难度低,运算耗时均值约2.5ms,对用户无感。方法用于粮食储藏信息化建设管理,可提供良好的安全保障。

不同储粮工况下柱承式立筒仓结构动力特性

柱承式立筒仓广泛应用于国家粮食储备,不同储粮工况对其结构动力特性影响显著。为揭示粮食散体对柱承式立筒仓动力特性的影响规律,结合某实际柱承式立筒仓设计制作了缩尺比例为1/25的有机玻璃筒仓模型,在空仓、半仓、3/4仓和满仓4种储粮状态下,进行了振动台模态试验、有限元数值分析和自振频率理论计算。结果表明:不同储粮工况对柱承式立筒仓试验模型的固有频率影响显著,随储粮状态变化,固有频率减小幅度较大,应在结构设计中加以考虑;空仓状态下阻尼比最小,满仓状态比空仓增大42.65%,仓内原有储粮越多,阻尼比增值越大,减震耗能效果越明显;有限元模型一阶固有频率与试验值平均误差为5.1%,所建有限元模型较为合理,为结构动力响应分析及结构设计提供一种合理的数值模拟方法;简化的三质点串联多自由度的弹性动力模型较为准确计算柱承式立筒仓在4种储粮工况下的固有频率,试验值与理论值平均误差为5.6%。研究结果可为柱承式立筒仓结构动力特性计算提供参考,为其抗震性能设计提供理论基础和试验依据。

我国粮食仓储设施建设与经济发展耦合协调的时空演化分析

利用2006—2020年中国31个省级行政区面板数据,在分析我国粮食仓储设施建设综合水平的基础上,对粮食仓储设施建设与经济发展耦合协调的时空演变特征进行研究,得出以下结论:在研究期内,我国粮食仓储设施建设综合评价值波动上升,空间上呈东高西低态势;粮食仓储设施建设与经济发展的耦合协调度偏低,呈上升-下降-上升趋势;耦合协调度的空间关联性自2009年开始逐渐显著,空间集聚程度呈北高南低的态势,空间演变格局具有向东北方向移动的集聚态势。根据研究结论,建议未来因地制宜提升不同省份粮食仓储设施建设与经济发展的协调匹配程度,以高耦合协调度地区带动周边地区发展,实现全国范围内粮食仓储设施建设与经济发展的协调进步。

收储制度市场化改革能提升玉米生产效率吗?——基于玉米主产区247地级市数据实证分析

党的十九大要求,加快推动粮食收储制度改革,保障国家粮食安全。党的二十大进一步指出,全方位夯实粮食安全根基,确保中国人的饭碗牢牢端在自己手里。收储制度市场化改革能否有效激发市场机制作用、提升粮食生产效率,对稳定国内粮食供给、保障国家粮食安全具有重要影响。利用2011-2020年玉米主产区247地级市面板数据,构建DID模型和中介效应模型,基于市场扭曲和市场风险双重视角分析收储制度改革对玉米全要素生产率的影响,并探讨其影响机制。结果表明:(1)收储制度改革对东北三省一区玉米全要素生产率总体呈现正向影响,但是随着改革的深入,全要素生产率增长幅度呈现波动变化;(2)收储制度改革的影响存在较大区域差异性,改革对于内蒙古和黑龙江两地呈现较为明显正向影响,尤其是对该地区第一、第四和第五积温带区域影响最为显著,而对吉林和辽宁两省影响并不明显;(3)收储制度改革通过缓解市场扭曲和加剧市场风险两条路径影响玉米全要素生产率,其中市场扭曲的缓解有助于提升玉米全要素生产率,而市场风险的加剧则减缓了玉米全要素生产率的增长。政府应该关注收储制度改革后玉米生产效率,充分发挥市场机制功能,同时配套抗风险、防波动稳定机制,以确保玉米生产高质量发展,保障国家粮食安全。

昆虫对低氧环境的适应性机制研究进展

昆虫需要利用氧气进行有氧呼吸,产生能量,维持正常的生命活动。在储藏环境中,可以利用气调技术控制环境中氧气的占比,以达到防治害虫的目的。然而害虫低氧适应性的发展为这项技术的推广和应用带来挑战。文章围绕低氧对昆虫生长发育、生命活动、生理功能的影响,以及昆虫适应低氧环境的补偿性策略,包括内在调控机制,生物学特性调节,代谢网络重构,基因调控等方面进行了综述。以期为害虫低氧适应性的产生机制提供新的研究线索,为绿色储粮技术的研究及发展提供参考。