高硅煤中Si-Al-Fe-Ca四元体系碳热反应研究

研究了不同温度条件下高硅煤中矿物组成比例下的Si-Al-Fe-Ca多元体系的碳热反应以及其影响因素。通过XRD和FESEM-EDS技术对各还原产物进行分析。结果表明,Fe_2O_3对含硅矿物的碳热反应起促进作用,Fe可以有效提高Si反应活性。CaO在较低温度时与灰中的Al_2O_3和SiO_2反应形成致密的Ca-Al-Si相共熔体CaAl_2Si_2O_8,阻碍含硅矿物碳热反应的进行。随着温度的升高,继续反应生成SiC、CaAl_4O_7和CaSiO_3。热力学模拟计算与实验结果基本吻合。     

一步法制备含W介孔碳材料及其氧化脱硫性能研究

以钨酸钠为钨源,以乙二胺四乙酸二钠为碳源经过高温煅烧制备了含W的介孔碳材料,采用XRD、SEM、FT-IR、BET对含钨的介孔碳材料进行表征。结果表明,煅烧后介孔碳材料的表面形成了粒状含有结晶水的氧化钨(WO_3·H_2O)。相比于纯的介孔碳材料,含钨介孔碳材料的总比表面积减小。以含W介孔碳材料为催化剂,H_2O_2作为氧化剂,1-丁基-3-甲基咪唑氟硼酸盐([BMIM][BF_4])离子液体作为萃取剂,组成萃取-催化氧化脱硫体系(ECODS)并研究其对模拟油中二苯并噻吩脱除效果。考察了氧化钨负载量、反应温度、H_2O_2加入量、催化剂用量、离子液体用量以及不同类型硫化物对二苯并噻吩脱除的影响。在最佳反应条件下,催化剂对二苯并噻吩(DBT)、4,6-二甲基二苯并噻吩(4,6-DMDBT)、苯并噻吩(BT)、噻吩(TH)和真实汽油的脱除率分别达到98.6%、65.6%、61.2%、57.8%和64.3%。催化剂回收利用五次之后脱硫率略有降低,仍高达95.2%。     

非经典碳正离子简介

非经典碳正离子作为一种特殊的反应中间体,具有重要的理论和实际研究的意义。本文以碳正离子理论的发展为主线,以历史上非经典碳正离子(特别是降冰片基正离子)之争为中心,简要综述了Winstein、Brown和Olah三人的观点,并结合最新进展进行评述。此外,还对除降冰片基正离子之外的非经典碳正离子进行了适当的讨论。     

TBAB包络化合物浆的管内流动再层流化现象

TBAB包络化合物浆是一种新型高密度潜热输送材料,在中央空调或区域供冷等系统中作为替代常规冷水的冷量输送媒体具有显著的节能应用前景.采用实验方法研究了A型TBAB包络化合物浆在水平直管内的层流和湍流流动特性.通过分析流动阻力随流速和固相含量等参数的变化规律,发现固相含量的增加有利于维持流动的层流趋势,在定流速条件下随着固相含量的增加流动状态会由湍流转变为层流,即出现"再层流化"现象,并且由于再层流化现象的出现,包络化合物浆的流动会出现"阻力降低区".     

Environmental Impacts on Spiking Properties in Hodgkin-Huxley Neuron with Direct Current Stimulus

Based on the well accepted Hodgkin-Huxley neuron model, the neuronal intrinsic excitability is studied when the neuron is subject to varying environmental temperatures, the typical impact for its regulating ways. With computer simulation, it is found that altering environmental temperature can improve or inhibit the neuronal intrinsic excitability so as to influence the neuronal spiking properties. The impacts from environmental factors can be understood that,the neuronal spiking threshold is essentially influenced by the fluctuations in the environment. With the environmental temperature varying, burst spiking is realized for the neuronal membrane voltage because of the environment-dependent spiking threshold. This burst induced by changes in spiking threshold is different from that excited by input currents or other stimulus.     

Different salinities water characterization by DSC-cooling

Water is a fundamental element of life. Its multiple uses are indispensable for a wide spectrum of human activities. This study aims to characterize water from different salinities obtained in the Cariri region of Paraíba, Brazil. The samples were analyzed using the DSC-coupled to the Peltier system (DSC-Cooling) and physical–chemical water tests performed employing reactive kits, using the Spectroquant Merck^? specific for each test. The calorimetric curves showed crystallization phase transitions with different characteristics in peak format and crystallization temperatures between the samples of different salinities. The calorimetric data obtained in the process of crystallization of water is directly correlated to the physico-chemical parameters of conductivity and total dissolved solids, showing that the analytical technology DSC-cooling/heating is suitable for characterization of different salinities water.     

Alkylation mechanism of benzene with 1-dodecene catalyzed by Et_3NHCl-AlCl_3

The isotope exchange method was employed to investigate the catalytic mechanism of ionic liquid in alkylation of benzenes with olefins.It is proposed that alkylation was induced by the Lewis acid AlCl3 which attracted π electrons of 1-dodecene to shift toward 1-carbon,thus forming a carbonium ion.The carbonium ion further reacted with benzenes to form a complex.Due to unstabilit of the complex,a deuterated ring proton was transferred into an electronegative 1-carbon of the side chain to substitute for the A...     

对数平均和双参数广义Muirhead平均之间的比较

本文讨论了两个不同正实数x和y的对数平均L(x,y)=(x-y)/(logx-logy)与双参数广义Muirhead平均M(a,b;x,y)=[(x~ay~b+x~by~a)/2]~(1/(a+b))之间的比较,得到了如下三个结论:(11)若(a,b)∈D_1∪E_1∪L_0,则M(a,b;x,y)L(x,y);(2)若(a,b)∈D_2∪E_2,则M(a,b;x,y)L(x,y);(3)若(a,b)∈D_3∪E_3,则存在x_1,y_1,x_2,y_2,使得M(a,b;x_1;y_1)L(x_1,y_1)和M(a,b;x_2,y_2)L(x_2,y_2).其中D_1={(a,b)∈R~2:a+b≠0,ba,ω_1(a,b)≤0,ω_2(a,b)≤0},E_1={(a,b)∈R~2:a+b≠0,ba,ω_1(a,b)≤0,ω_2(a,b)≤0},D_2={(a,b)∈R~2:ab≤0,ba,ω_1(a,b)≥0},E_2={(a,b)∈R~2:ab≤0,ba,ω_1(a,b)≥0},D_3={(a,b)∈R~2:ba0,ω_1(a,b)0)∪{(a,b)∈R~2:ba0,ω_1(a,b)=0,ω_2(a,b)0}∪{(a,b)∈R~2:ba,ab≤0,ω_1(a,b)0,ω_2(a,b)0},E_3={(a,b)∈R~2:ab0,ω_1(a,b)0}∪{(a,b)∈R~2:ab0,ω_1(a,b)=0,ω_2(a,b)0}∪{(a,b)∈R~2:ab,ab≤0,ω_1(a,b)0,ω_2(a,b)0},L_0={(a,b)∈R~2:a=b≠0},ω_1(a,b)=(a+b)[3(a-b)~2-(a+b)],ω_2(a,b)=(a+b)[2(a-b)~2+1]-3(a~2+b~2).     

早期干预对极低出生体重早产儿智能发育的影响研究

目的 探讨早期干预对极低出生体重早产儿智能发育的影响,为极低出生体重早产儿的早期干预提供依据。方法 239 例极低出生体重早产儿为早产随访组,采用鲍秀兰早期教育资料制定的干预计划,进行系统干预,并与326 例失访的早产儿童以及与随访组相似的326 例正常儿童进行对照分析。采用Gesell 儿童发育量表等标准化工具进行发育评估。结果 早产随访组Gesell 儿童发育量表5 项均分、总发育商（developmental quotient,DQ）总分与早产失访组相比差异均有统计学差异（均P＜0.05）。结论 早期干预能显著促进极低出生体重早产儿的智能发育,提高患儿的生活质量。