Application of ferrous sulfate alleviates negative impact of cadmium in rice (<i>Oryza sativa</i> L.)

Soil contamination with toxic heavy metals [such as cadmium (Cd)] is becoming a serious global problem due to rapid development of social economy. Iron (Fe), being an important element, has been found effective in enhancing plant tolerance against biotic and abiotic stresses. The present study investigated the extent to which different levels of Ferrous sulphate (FeSO₄) modulated the Cd tolerance of rice (Oryza sativa L.), when maintained in artificially Cd spiked regimes. A pot experiment was conducted under controlled conditions for 146 days, by using natural soil, mixed with different levels of CdCl₂ [0 (no Cd), 0.5 and 1 mg/kg] together with the exogenous application of FeSO₄ at [0 (no Fe), 1.5 and 3 mg/kg] levels to monitor different growth, gaseous exchange characteristics, oxidative stress, antioxidative responses, minerals accumulation, organic acid exudation patterns of O. sativa. Our results depicted that addition of Cd to the soil significantly (P < 0.05) decreased plant growth and biomass, gaseous exchange parameters, mineral uptake by the plants, sugars (soluble, reducing, and non-reducing sugar) and altered the ultrastructure of chloroplasts, plastoglobuli, mitochondria, and many other cellular organelles in Cd-stressed O. sativa compared to those plants which were grown without the addition of Cd in the soil. However, Cd toxicity boosted the production of reactive oxygen species (ROS) by increasing the contents of malondialdehyde (MDA), which is the indication of oxidative stress in O. sativa and was also manifested by hydrogen peroxide (H₂O₂) contents and electrolyte leakage to the membrane bounded organelles. Although, activities of various antioxidative enzymes like superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) and non-enzymatic antioxidants like phenolics, flavonoid, ascorbic acid, anthocyanin and proline contents increased up to a Cd level of 0.5 mg/kg in the soil but were significantly diminished at the highest Cd level of 1 mg/kg in the soil compared to those plants which were grown without the addition of Cd in the soil. The negative impacts of Cd injury were reduced by the application of FeSO₄ which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes, minerals uptake together with diminished exudation of organic acids as well as oxidative stress indicators in roots and shoots of O. sativa by decreasing Cd retention in different plant parts. These results shed light on the effectiveness of FeSO₄ in improving the growth and upregulation of antioxidant enzyme activities of O. sativa in response to Cd stress. However, further studies at field levels are required to explore the mechanisms of FeSO₄-mediated reduction of the toxicity of not only Cd, but possibly also other heavy metals in plants.     

AlF3-modified LiCoPO4 for an advanced cathode towards high energy lithium-ion battery

Surface-interface reaction between the electrode and electrolyte plays a key role in lithium-ion storage properties, especially for high voltage cathode such as LiCoPO₄ and Ni-riched cathode. Generally, surface modification is an effective method to improve the electrochemical performance of electrode materials. Herein, in order to revise the LiCoPO₄ cathode with desirable properties, uniform AlF₃-modified LiCoPO₄ (LiCoPO₄@AlF₃) cathode materials in nano-sized distribution are synthesized. XRD result indicates that there is no structural transformation observed after AlF₃ coating. TEM characterization and XPS analysis reveal that the surface of LiCoPO₄ particle is coated by a nano-sized uniform AlF₃ layer. Further, the electrochemical results indicate that AlF₃ layer significantly improves the cycling and rate performances of LiCoPO₄ cathode within the voltage range of 3.0–5.0 V. After a series of optimization, 4 mol% AlF₃-coated LiCoPO₄ material exhibits the best properties including an initial discharge capacity of 159 mA h g^?1 at 0.1 C with 91% capacity retention after 50 cycles, especially a discharge capacity of 90 mA h g^?1 can be obtained at 1 C rate. CV curves indicate that the polarization of cathode is reduced by AlF₃ layer and EIS curves reveal that AlF₃ layer relieves the increase of resistance to facilitate Li-ion transfer at the interface between electrode and electrolyte during the cycling process. The enhanced electrochemical performances are attributed to that the AlF₃ layer can stabilize the interface between the cathode and electrolyte, form steady SEI film and suppress the electrolyte continuous decomposition at 5 V high voltages. This feasible strategy and novel characteristics of LiCoPO₄@AlF₃ could promise the prospective applications in the stat-art of special lithium-ion battery with high energy and/or power density.     

锚索的锈蚀、防护及永久锚索的合理结构

随着锚索在岩土工程加固中的普及，近期人们普遍关注的焦点是锚索的永久性问题。锚索的永久性与锚索的结构和锚索材料有关，也与锚索所处环境及人为因素有关。本试图就锚索可能遭到的破坏因素及防护，提出永久锚索的合理结构，供同行参考。     

关于瓦斯、煤尘爆炸监控预防综合一体化可行性研究

为了避免瓦斯爆炸及瓦斯爆炸引发煤尘二次爆炸,最大限度降低爆炸强度,设想对井下电子监测监控系统进行综合升级改造研究,形成瓦斯、风量、煤尘系统、关联、综合监测,并根据监测数据,主动做出相关防范动作,从而实现井下瓦斯、煤尘爆炸监测监控、预防、治理的系统化、一体化、自动化,通过分析研究,该设想具有科学性和可操作性,对预防瓦斯爆炸、遏制瓦斯爆炸引发二次爆炸具有积极作用。     

网络系统资源数据的脆弱性漏洞防御控制仿真

当前漏洞防御控制方法存在着无法准确区分数据类型或脆弱性,需要较高的能量消耗和难以抵御某些未知攻击等不足。针对这些不足,提出网络系统资源数据脆弱性漏洞防御控制方法。根据属性划分网络系统运行数据和历史资源,属性划分后根据漏洞特征相关参数构建强关联规则,结合脆弱性漏洞辨识矩阵和数据关联规则构建漏洞检测模型;计算脆弱性漏洞利用难度,将防御任务优选问题描述为防御成本不高于给定值的条件下,获取造成最小损失的防御措施集的过程。把防御任务优选多目标优化问题转换成单目标优化问题,采用改进的蚁群算法求解优化问题,生成最优防御控制方案。实验结果表明,所提方法可以有效防御已知数据攻击和大部分未知数据攻击,且所需能耗较低。     

空间信息系统在弹道导弹防御中的效能评估框架

针对空间信息系统在弹道导弹防御(BMD)中的效能评估问题,从系统整体性和复杂性角度提出了空间信息系统在BMD中的效能评估框架.该框架主要包括整体性分析、综合集成以及结果分析3个部分.在整体性分析中,通过系统学模型确定导弹防御的边界、要素集和关系集.在综合集成中,应用基于Agent的建模与仿真方法对系统要素进行建模,并对...     

明长城居庸关防区军事聚落空间布局研究

居庸关防区是明代拱卫京师的重要 屏障和连通内外的核心枢纽,是明长城体系 中大型关城防区的典型代表。其空间控制力 范围远超过居庸关关城边界,是经长期发展 形成沿太行山脉五路分守的居庸关防区。本 研究基于历史典籍中对居庸关防区聚落军事 属性的记载,经现场踏勘考察定位,在厘清 居庸关防区层次体系的基础上,建立可融入 明长城整体框架的居庸关防区军事聚落信息 数据库。分析得到居庸关防区军事聚落空间 布局总体特征及其与驻军数量分布和自然地 理环境的相关关系。其一,防区聚落分布与 战事分布趋同,形成西路与关沟两个中心; 其二,防区边缘聚落密度高、驻军密度小、 前哨作用突出,防区腹地聚落密度低、驻军 密度高、屯兵作用突出;其三,除长城边墙沿线外,防区内聚落多设置在海拔较低、坡度较小、南向采光较多的区域。这一方法与结 论,对明长城军事聚落空间布局的整体性研究和重要关城节点军事作用机制的讨论与现代 保护策略的制定均有重要意义和参考价值。     

基于DHT的消息转发防御机制研究

DHT（Distributed Hash Tables）是结构化P2P（Peer to Peer）系统实现资源高效组织和定位的关键技术。对DTH系统中消息转发过程中的安全威胁及其解决方法进行了分析。以多路径算法为基础,对消息转发效率和安全性进行优化,提出了一种混合路由防御机制。首先结合迭代路由与递归路由的优点,设计了混合路由方式,保证了消息的转发效率并降低消息开销。然后改进了消息转发过程中的可靠性和消息源鉴别机制。最后,在四川大学校园网内进行了测试。仿真试验结果表明,采用混合路由下的防御机制在减少消息数量的同时提高了查询成功率,对于消息转发过程中的攻击有着较好的防御效果。     

基于DoDAF的C2BMC系统作战视图研究

首先简要介绍了美军导弹防御的指挥控制、作战管理与通信系统(command and control,battle management and communications,C2BMC)系统和国防部体系结构框架(Department of Defense architecture framework,DoDAF)的基本情况,确定了作战视图产品的建模方法和开发步骤,然后利用Telelogic公司的System Architect(SA)软件完成了作战视图(operational view,OV)的分析与设计,为理解指控系统内在规律、开展指控系统顶层设计研究提供理论支持,对于开展其他复杂系统的体系结构研究也具有借鉴意义。     

刍议计算机网络防御策略建设方法及模型优化方案

随着科学技术的发展,网络技术在人们日常生活中占据着越来越重要的作用,带给人们生活和工作很大便利与益处,然而,与此同时由于网络的安全问题日益突出,威胁着人们的财产安全以及人身安全,比如数据遭窃、木马病毒或者黑客入侵等,这给计算机网络安全防御系统带来了极大的挑战.所以如何在网络大环境下做好网络安全防御工作,保障人民财产安全是一个亟待解决的问题,也是当前困扰互联网技术人员的一个首要问题.本文就从计算机网络所受到的安全威胁入手展开对这一问题的探讨.