不同材质的重载齿轮热处理后的疲劳性能研究

齿轮是一种普遍使用的传动件,其疲劳性能对机械装备的使用寿命具有极其重要的影响。为了弄清齿轮的材料和热处理工艺对齿轮疲劳性能的影响,分别采用42CrMo、22CrNi2MoNb、20CrMnMo和20CrMnTi钢等4种材料制作了一种推土机用重载齿轮,并进行了不同工艺的热处理:42CrMo钢齿轮离子渗氮,渗层深度>0.4 mm;22CrNi2MoNb、20CrMnMo和20CrMnTi钢齿轮渗碳和淬火,渗层深度1.8～2.4 mm。随后检测了齿轮的显微组织和硬度,进行了断口分析,并在120 kN的载荷下进行了疲劳试验。结果表明:经离子渗氮的42CrMo钢齿轮由于渗层较浅,其疲劳性能比渗碳淬火的其余三种钢齿轮差;而三种经渗碳和淬火处理的齿轮中,22CrNi2MoNb钢齿轮由于含碳量稍高,晶粒较细小及强韧性较好,疲劳性能最佳。

Studies on Thermodynamic Properties of Adsorption of Theophylline by Phenolic Resin Adsorbents

In the present work,the equilibrium adsorption of theophylline was studied by phenolic resin adsorbents: JDW\|2(made by ourselves) and Duolite S\|761 within a temperature range of 303\_323 K. The experimental results show that the Freundlich adsorption law is applicable to the adsorption of theophylline on the two adsorbents,the exponents \%n\%>1 indicate that they are favorable to the adsorptions;the negative values of all the isosteric adsorption enthalpies for the theophylline indicate the exothermic process of the adsorption,while the range(10\_40 kJ/mol) of their magnitudes manifests the physisorption process;other thermodynamic properties,the free energy changes and the entropy change associated with adsorption have been calculated from the Gibbs adsorption equation and the Gibbs\|Helmholtz equation.

华中地区79家医院急诊脓毒症诊治现状调查分析

目的:了解当前湖北省急诊脓毒症诊治现状及急诊医务人员对脓毒症的认知情况。方法:采用德尔菲法并依据脓毒症指南与专家共识自行设计的急诊脓毒症现状调查问卷,对华中地区共17个地级市、自治州或省直辖县级行政单位的79家医院急诊科150名医生的脓毒症诊治现状进行了调查。结果:急诊医务人员对中国预防脓毒症行动(PSCC)的知晓率仅有39.3%,脓毒症Hour-1 bundle的知晓率为53.3%。Hour-1 bundle中血培养依从性最低,仅有45.3%,大部分人认为不能实施的原因是急诊条件有限。急诊医务人员认为影响脓毒症诊治效果最主要的原因是早期识别能力有限,诊断不及时(34.0%),更愿意通过专家讲座来学习脓毒症的知识。结论:建议加强急诊脓毒症患者筛查、诊断与管理的培训,提高脓毒症患者早期识别率,通过对围脓毒症期患者的合理诊治,降低脓毒症的病死率。