GSH-responsive polyglutamic acid nanocarriers for dual targeted cancer therapy

In order to reduce the toxic side effects of chemotherapeutic drugs and improve the targeting and efficiency of cancer treatment, the development of drug delivery system has received great attention. In this study, second generation polyglutamic acid dendrimers (G₂) are used as basic materials to produce porous nanoparticles through cross link by crosslinkers containing disulfide bonds. The crosslinked products (G₂)_n have negative electricity and abundant voids, which enable them to adsorb the electronegative anticancer drug DOX. At the same time, in order to transport DOX to the tumor site, we modified FA on DOX and encapsulated it in magnetic mesoporous silica (FA-DOX-MSNs). Therefore, the final nanoparticles (FA-DOX-MSNs/(G₂)_n) not only have dual targeting ability to transport DOX to the tumor site, but also have reductive responsiveness that can release drugs responsively in the tumor cells. In addition, it has good biocompatibility and endocytosis ability.     

基于Bp神经网络的矿井热环境评价体系研究

为了科学评价矿井热环境,系统地考虑了内部热源、环境、矿井结构三个方面因素,构建了评价指标,以人对矿井热环境的适应性确立分级指标,建立一个新的矿井热害评价指标体系。运用MATLAB软件对评价指标体系进行神经网络建模,对矿井热环境问题定量化评价、分析。通过对张双楼煤矿热害改造前后的实际生产情况进行评价该矿井热环境体系能准确地反映矿井实际生产情况。该系统简单、可操作性强,可以用来进行矿井热环境的评价工作,也可以预测矿井热害改造后的情况。     

基于组合赋权-集对分析的煤矿煤尘爆炸危险性评价研究

针对目前煤尘爆炸危险性评价研究较少、各评价因素选择偏差较大的问题,通过分析煤尘爆炸特性,提出以煤尘可爆性危险、煤尘爆炸浓度危险、点火源危险3个必要条件为一级指标,煤质变异程度、挥发分、水分、灰分等14个二级指标,以层次分析法确定各指标的主观权重,以熵权法确定各指标的客观权重,利用乘法归一化方法对各指标的组合权重进行计算,构建集对分析-组合赋权煤尘爆炸危险性评价模型,并将该模型与已较成熟的改进FAHP模型、模糊事故树模型、灰色聚类评估体系、未确知测度评价模型一同应用于济宁某矿的煤尘爆炸危险性评价过程中,结果显示:集对分析-组合赋权评价模型、改进FAHP模型、灰色聚类评估体系评价结果为一般危险等级,模糊事故树模型的评价结果为较安全等级,集对分析-组合赋权煤尘爆炸危险性评价模型评价结果与改进FAHP模型、灰色聚类评估体系、未确知测度评价模型的评价结果一致,该模型对煤尘爆炸危险的评价具有较好的适用性。     

青海拉脊山地区新发现矿化点地质特征及找矿前景分析

通过对青海拉脊山地区开展1:5万区域地质调查,摸清了该区域地层特征及含矿性情况,以及在本次区域地质调查工作基础上,新发现的矿(化)点9处,主要有成矿潜力点5处,即上龙湾北石墨矿点、来路村北铁矿化点、俄加萤石矿点、松巴铜矿点、上峡铁矿点、红嘴滩泥炭矿点。结合拉脊山一带的区域地质背景,综合研究了该地区成矿地质条件,对该区域的找矿前景进行了分析。     

淮南采煤沉陷区积水重金属健康风险评价

为研究淮南采煤沉陷区积水中重金属对人体产生的潜在健康风险,对9个矿19个沉陷水域进行采样,测试5种重金属(Cd、Cr、Pb、Ni、Zn)含量,采用美国环境保护局(USEPA)推荐使用的健康风险评价模型,对其进行健康风险评价。研究结果表明：(1)采样水域5种重金属年平均离子浓度由大到小依次为：Zn＞Cr＞Ni＞Pb＞Cd,重金属的分布影响因素可能与农药化肥的使用、工业废水的排放、汽车尾气中重金属的大气沉降、渔业养殖以及采煤活动等因素有关；(2)重金属的健康风险值总体随季节变化,呈现出丰水期小于枯水期的特点；该区域沉陷积水的重金属致癌风险整体较为安全,但化学致癌物(Cr)的健康风险值超出其它4种重金属4~8个数量级；(3)5种重金属的健康风险平均值排序为：Cr＞Cd＞Pb＞Zn＞Ni,其中Cd的致癌风险值及Pb、Zn、Ni非致癌风险值均低于最大可接受风险值(5.05×10-5a-1)。     

Thermodynamic analysis of a novel fossil-fuel–free energy storage system with a trans-critical carbon dioxide cycle and heat pump

This paper presents and analyzes a novel fossil-fuel–free trans-critical energy storage system that uses CO₂ as the working fluid in a closed loop shuttled between two saline aquifers or caverns at different depths: one a low-pressure reservoir and the other a high-pressure reservoir. Thermal energy storage and a heat pump are adopted to eliminate the need for external natural gas for heating the CO₂ entering the energy recovery turbines. We carefully analyze the energy storage and recovery processes to reveal the actual efficiency of the system. We also highlight thermodynamic and sensitivity analyses of the performance of this fossil-fuel–free trans-critical energy storage system based on a steady-state mathematical method. It is found that the fossil-fuel–free trans-critical CO₂ energy storage system has good comprehensive thermodynamic performance. The exergy efficiency, round-trip efficiency, and energy storage efficiency are 67.89%, 66%, and 58.41%, and the energy generated of per unit storage volume is 2.12 kW·h/m³, and the main contribution to exergy destruction is the turbine reheater, from which we can quantify how performance can be improved. Moreover, with a higher energy storage and recovery pressure and lower pressure in the low-pressure reservoir, this novel system shows promising performance.     

Chemo-mechanical coupling model of solid oxide fuel cell under high-temperature oxidation

Solid oxide fuel cell (SOFC), which is a generation device that converts chemical energy into electrical energy, has been regarded as a new generation device. The diffusion mechanism of metal cations and anions during the high-temperature oxidation process of SOFC is proposed. Based on the equilibrium expression and diffusion equation, the chemo-mechanical coupling relationship between oxide stress and thickness growth of the oxide layer is established by considering the influences of viscoplastic effect and oxide growth effect. The present theoretical result is consistent with the previous experimental results. In addition, the stress critical points corresponding to different parameters are different in initial oxidation stage. The oxide stress varies dramatically with time in the compressive stress phase, but it changes slowly in the tensile stress phase. The compressive stress that exists in the oxide layer increases with the growth coefficient (D_NiO = 1000-15 000 m⁻¹) of the oxide layer. The oxide stresses in oxide layer and electrolyte reduce with viscoplastic coefficient of the oxide layer from J_NiO = 8.97 × 10⁻⁵ Pa⁻¹ s⁻¹ to J_NiO = 16.97 × 10⁻⁵ Pa⁻¹ s⁻¹ and anode-oxide layer thicknesses from H = 30 μm to H = 660 μm, while they increase with viscoplastic coefficient of the anode from J_Ni = 3.81 × 10⁻⁵ Pa⁻¹ s⁻¹ to J_Ni = 12.81 × 10⁻⁵ Pa⁻¹ s⁻¹ and kinetic parabolic constant from k _p = 2.9 × 10⁻¹⁵ m²s⁻¹ to k _p = 12.9 × 10⁻¹⁵ m²s⁻¹ in whole oxidation stage. The oxide thickness increases with kinetic parabolic constant in the whole oxidation stage and this changing trend accords with parabolic diffusion law. The oxide thickness increases with temperatures increasing. The results obtained from this study will provide the reference to the researches of the chemo-mechanical coupling model and performance optimization of SOFC under high-temperature oxidation.     

稀燃及废气再循环提高增压汽油机热效率的对比研究

在一台直列4缸增压直喷汽油机上针对万有特性最低油耗工况点,进行了稀薄燃烧与废气再循环(exhaust gas recirculation,EGR)提高发动机热效率的对比试验研究。试验结果表明:稀薄燃烧及EGR均能有效降低发动机燃油消耗率,稀释率分别为33%和19%时,采用稀燃和EGR时的最高有效热效率绝对值分别增加2.8%和1.7%,其中稀燃的有效热效率达到了39.9%,稀燃实现更高热效率主要归因于较低的传热损失和未燃损失。从燃烧角度来看,稀燃及EGR稀释都延长了燃烧滞燃期及持续期,但同样稀释率下稀燃的滞燃期更短,稀燃更高的稀释极限实现了更低的传热损失;但EGR抑制爆震,提前燃烧相位,使采用EGR时的排气能量损失低于稀燃。从排放角度来看,稀燃及EGR在高稀释率下均显著降低NO_x排放,而受益于高氧气浓度,相同稀释率下稀燃的HC及CO排放均低于采用EGR时,从而使稀燃的未燃损失更低。     

P水电站一管三机机组功率波动的分析与消除

针对P电站一管三机水电机组功率波动现象,发现水力不稳定是引起机组功率波动的主要原因,建立了一管三机引水系统的数值计算模型,计算结果表明球形分岔处的不稳定漩涡是导致水轮机蜗壳压力大幅波动的原因。在实际工程中加装导流板后,机组功率平稳,球形分岔处的漩涡消失,解决了水力不稳定的问题。