Nickel foam and stainless steel mesh as electrocatalysts for hydrogen evolution reaction,oxygen evolution reaction and overall water splitting in alkaline media

In this work, several commonly used conductive substrates as electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under alkaline conditions were studied, including nickel foam (Ni foam), copper foam (Cu foam), nickel mesh (Ni mesh) and stainless steel mesh (SS mesh). Ni foam and SS mesh are demonstrated as high-performance and stable electrocatalysts for HER and OER, respectively. For HER, Ni foam exhibited an overpotential of 0.217 V at a current density of 10 mA cm⁻² with a Tafel slope of 130 mV dec⁻¹, which were larger than that of the commercial Pt/C catalyst, but smaller than that of the other conductive substrates. Meanwhile, the SS mesh showed the best electrocatalytic performance for OER with an overpotential of 0.277 V at a current density of 10 mA cm⁻² and a Tafel slope of 51 mV dec⁻¹. Its electrocatalytic performance not only exceeded those of the other conductive substrates but also the commercial RuO₂ catalyst. Moreover, both Ni foam and SS mesh exhibited high stability during HER and OER, respectively. Furthermore, in the two-electrode system with Ni foam used as the cathode and SS mesh used as the anode, they enable a current density of 10 mA cm⁻² at a small cell voltage of 1.74 V. This value is comparable to or exceeding the values of previously reported electrocatalysts for overall water splitting. In addition, NiO on the surface of Ni foam may be the real active species for HER, NiO and FeO_x on the surface of SS mesh may be the active species for OER. The abundant and commercial availability, long-term stability and low-cost property of nickel foam and stainless steel mesh enable their large-scale practical application in water splitting.

Efficient electrocatalytic overall water splitting is achieved with commercially-available and low-cost nickel foam and stainless steel mesh as cathode and anode electrodes.     

案例教学法在《PHOTOSHOP平面设计》课程中的运用

在Photoshop这类操作软件的教学中,仅使用传统的教学方法,达不到应有的教学效果；适当结合案例教学法,可以提高教学效率,达到更好的教学效果。本文通过一次案例教学课程的实例,从理论和实践上对案例教学法的应用进行了探讨,提出了在案例教学中应注意的问题和相关的建议。     

分布式虚拟现实协同学习环境的研究及实现

分布式虚拟现实系统不但可以提供强大的计算能力,而且还可以使多个用户通过网络进行协同工作.文章通过分析分布式虚拟现实系统中的若干关键技术--客户端环境、与数据库系统的连接、时钟同步以及分布式环境等,提出了利用现有的分布式体系结构来构建一个分布式虚拟现实协同学习环境的想法.     

虚拟现实技术在心理焦虑治疗中的应用

目前很多学生存在心理焦虑现象，这不仅影响他们的学习成绩，而且影响着他们的身心健康。传统的方法在治疗心理焦虑时效果会受到患者个人因素的影响，利用虚拟现实技术设计一套治疗方案，可以降低在治疗过程中患者个人因素的参与，增加患者对客观因素的感受，从而提高治疗效果。     

三叶半夏组培苗生长情况调查

目的为半夏快速繁殖技术体系的建立提供理论依据。方法通过一步成苗法获得半夏组培苗后进行移栽实验,并进行形态学观察和产量统计。结果半夏组培苗三种不同叶形的叶柄上均可萌生珠芽,块茎越大的植株大多出现三出复叶的时间较早,其产生的珠芽数也越多,且在移栽的当年就可长出佛焰苞;在一个生长期之后,母块茎的收获重量可达到栽种量的31.7倍;两批半夏组培苗的无性繁殖系数分别达到了12.8个/株和10.1个/株。结论半夏组培苗具有生长速度快,繁殖系数高的特点。     

徐州市城市居民生活垃圾产生量研究

探讨了影响徐州市城市居民生活垃圾产生量的因素:内在因素、个体因素、社会因素.其中内在因素居主导地位,首先表现在城市规模越大,聚居人13越多,产生的垃圾量也越多,其次随着生活水平提高,徐州市城市居民GDP的增长,城市居民生活垃圾产生量明显增加;个体因素包括个体的行为习惯、生活方式、受教育程度等对垃圾产生量的影响;社会因素主要表现在有关垃圾减量、回收、再利用等措施的实施.建立并研究了人均GDP预测模型,该模型可以预测未来徐州市城市居民生活垃圾产生量.     

Diastereoselective synthesis of chroman bearing spirobenzofuranone scaffolds via oxa-Michael/1,6-conjugated addition of para-quinone methides with benzofuranone-type olefins

A simple and convenient cyclization of ortho-hydroxyphenyl-substituted para-quinone methides with benzofuran-2-one type active olefins via oxa-Michael/1,6-conjugated addition has been developed, which afforded an easy access to enriched functionalized chroman-spirobenzofuran-2-one scaffolds with good to excellent yields (up to 90%) and diastereoselectivities (up to >19 : 1 dr). This reaction provided an efficient method for constructing desired spirocyclic compounds combining both well-known heterocyclic pharmacophores chroman and benzofuran-2-one.

Highly diastereoselective synthesis of spirocyclic compounds combining both well-known heterocyclic pharmacophores chroman and benzofuran-2-one.

The chroman framework represents a privileged heterocyclic core commonly found within a wide variety of biologically active natural products¹ and synthetic compounds of medicinal interest (Fig. 1).² Owing to the wide application of these heterocyclic molecules, over the past few decades, numerous efforts have been devoted to the efficient synthesis of chroman nucleus motifs.^3,4 In particular, incorporating chroman into spiro-bridged and spiro-fused heterocyclic systems is appealing due to its fascinating molecular architecture and proven biological activity.⁵ Among the existing methods, the [4 + m] cycloaddition of para-quinone methides (p-QMs) is found to be an efficient pathway to access these valuable spirocyclic skeletons.⁶ For instance, the Enders group synthesized functionalized chromans with an oxindole motif by the asymmetric organocatalytic domino oxa-Michael/1,6-addition reaction.⁷ After that, the Hao,^8a Peng,^8b Shi,^8c,d Zhou,^8e Liang^8f and Wang^8g groups developed convenient methods to construct chromans bearing spirocyclic skeletons from p-QMs, respectively. Despite all these shining achievements, however, it is still very challenging to simply and conveniently construct chromans bearing quaternary carbon spirals for organic chemical or drug discovery among these [4 + m] cycloaddition reactions.Open in a separate windowFig. 1Representative chroman compounds.Benzofuran-2-(3H)-ones as one of the important oxygen-containing heterocycles that exist in a broad array of natural products⁹ and potential medicines.¹⁰ The streamlined synthesis of benzofuran-2-ones pose considerable challenge due to their quaternary carbon centers at the C-3 position,¹¹ especially those featuring relatively congested spirocyclic motifs represent challenging synthetic targets.^12,13 In our continuous interests in developing efficient method for the synthesis of spirocyclic compounds based on cyclization reaction,¹⁴ we wish to report a cycloaddition of para-quinone methides with benzofuranone derived olefins, affording the spiro-cycloadducts in good to excellent yields and diastereoselectivities. This cyclization features the simultaneous formation of chroman and spirobenzofuran-2-one skeletons in a single step (Scheme 1), which may be potentially applied as pharmaceutical agents.Open in a separate windowScheme 1Strategy for the synthesis of chroman-spirobenzofuran-2-one.We initiated our investigations with the readily available ortho-hydroxyphenyl-substituted para-quinone methides 1a and 3-benzylidenebenzofuran-2-one 2a in toluene at room temperature in the presence of base. Unfortunately, no desired chroman derivatives bearing spirobenzofuranone scaffolds 3a was isolated in the presence of 2 eq. Na₂CO₃ after stirring at room temperature for 48 h (entry 1,

大学生抑郁和人格关系初探

目的　考察大学生的抑郁情绪和与人格的关系。方法　采用流调中心用抑郁量表和人格问卷 ,对从西华师范大学、重庆三峡学院和四川大学随机抽取的 71 2名大一至大四的学生进行测查 ,并进行有关的统计分析。结果　 1大学生的抑郁表现出明显的年龄特征和性别差异 ;2大学生的抑郁与人格间有负相关 ,且具有统计学显著性。结论　独立性、社交性和进取能力对抑郁均有重要的预测作用     

不同遮荫条件下巫山淫羊藿生长状态及生理变化的研究

目的:通过分析不同光照条件下(100%,80%,60%,40%,20%)巫山淫羊藿的各项生长指标和生理指标,探讨巫山淫羊藿对遮荫环境的生理适应机制,为药用淫羊藿生产栽培提供理论依据。方法:以巫山淫羊藿为研究对象,测定了不同遮荫处理下巫山淫羊藿植株形态指标、光和色素含量、脯氨酸含量、丙二醛含量、可溶性糖含量、可溶性蛋白含量、抗氧化性酶活性。结果:除长宽比差异不显著外,其他形态指标都出现显著性变化,在80%~40%光强处理下的巫山淫羊藿生长良好,地上部分生物量相对较高;遮荫后叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量增加,叶绿素a/叶绿素b的值在100%~60%光强处理下逐渐增大,60%~20%光强处理下逐渐减小;遮荫后脯氨酸、丙二醛含量降低;可溶性糖、可溶性蛋白含量分别在100%~60%,100%~40%光强处理下逐渐增加,60%~20%,40%~20%光强处理下逐渐下降;遮荫后SOD,CAT活性值减小;POD,APX活性值在100%~40%光强处理下逐渐减小,在20%光强处理下有所增大。结论:80%~40%光强处理有利于巫山淫羊藿生长。     

职业院校学生学校归属感探微

随着我国职业教育改革的深入,职业院校学生学校归属感的缺失日益凸显,如何建构学生的学校归属感成了职业院校德育教育中面临的一个新课题。