摘要：Electrocatalysis is a promising approach to clean energy conversion due to its high efficiency and low environmental pollution. Noble metal materials have been studied to show high activity toward electrocatalyltic reactions, although such applications remain restricted by the high cost and poor durability of the noble metals. By precisely adjusting the catalyst composition, size, and structure, electrocatalysts with excellent performance can be obtained. Atomic layer deposition(ALD) is a technique used to produce ultrathin films and ultrafine nanoparticles at the atomic level. It possesses unique advantages for the controllable design and synthesis of electrocatalysts. Furthermore, the homogenous composition and structure of the electrocatalysts prepared by ALD favor the exploration of structure-reactivity relationships and catalytic mechanisms. In this review, the mechanism, characteristics, and advantages of ALD in fabricating nanostructures are introduced first. Subsequently, the problems associated with existing electrocatalysts and a series of recently developed ALD strategies to enhance the activity and durability of electrocatalysts are presented. For example, the deposition of ultrafine Pt nanoparticles to increase the utilization and activity of Pt, fabrication of core–shell, overcoat, nanotrap, and other novel structures to protect the noble-metal nanoparticles and enhance the catalyst stability. In addition, ALD developments in synthesizing non-noble metallic electrocatalysts are summarized and discussed. Finally, based on the current studies, an outlook for the ALD application in the design and synthesis of electrocatalysts is presented.

摘要：An atomic layer deposition （ALD） method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic （EM） absorption properties compared to the pristine graphene. The optimal reflection loss （RL） reaches -46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.

摘要：Impedance matching is important for achieving high-efficiency microwave absorbers. The high conductivity of dielectric loss materials such as pure metals and carbon nanomaterials generally results in poor absorption owing to the low impedance matching between the absorbers and air. Carbon nanostructures are very promising candidates for high-efficiency absorption because of their attractive features including low density, high surface area, and good stability. Herein, a new strategy is proposed to improve the impedance matching of dielectric loss materials using electrospun carbon nanofibers as an example. The carbon nanofibers are coated with specifically designed gradient multilayer nanofilms with gradually increasing electroconductibility synthesized by doping ZnO with different A1203 content （AZO） by atomic layer deposition. The gradient nanofilms are composed of five layers of dielectric films, namely, pure A1203, AZO （5：1, the pulse cycle ratio of ZnO to A1203）, pure ZnO, AZO （10：1）, and AZO （20：1）. The versatile gradient films serve as intermediate layers to tune the impedance matching between air and the carbon nanofiber surfaces. Therefore, the carbon nanofibers coated with gradient films of rationally selected thicknesses exhibit remarkably enhanced microwave absorption performance, and the optimal reflection loss reaches -58.5 dB at 16.2 GHz with a thickness of only 1.8 mm. This work can help further understand the contribution of impedance matching to microwave absorption. Our strategy is general and can be applied to improve the absorption properties of other dielectric loss materials and even for applications in other fields.

摘要：Empirical likelihood （EL） ratio statistic on θ=g（x） is constructed based on the inverse probability weighted imputation approach in a nonparametric regression model Y = g（x） ＋ε （x ∈ [0, 1]p） with fixed designs and missing responses, which asymptotically has X1^2 distribution. This result is used to obtain a EL based confidence interval on θ.

摘要：Suppose that we have a partially linear model Yi = xiβ ＋ g（ti） ＋εi with independent zero mean errors εi, where （xi,ti, i = 1, ... ,n} are non-random and observed completely and （Yi, i = 1,...,n} are missing at random（MAR）. Two types of estimators of β and g（t） for fixed t are investigated： estimators based on semiparametric regression and inverse probability weighted imputations. Asymptotic normality of the estimators is established, which is used to construct normal approximation based confidence intervals on β and g（t）. Results are reported of a simulation study on the finite sample performance of the estimators and confidence intervals proposed in this paper.

摘要：AIM:To investigate a newly designed stent and its dilatation effect in a rabbit model of benign esophageal ***:Thirty-four New Zealand white rabbits underwent a corrosive injury in the middle esophagus for esophageal stricture *** rabbits with a successful formation of esophageal strictures were randomly allocated into two *** control group(n = 15) was implanted with a conventional stent,and the study group(n= 15) was implanted with a detachable "pieced" *** study stent(30 mm in length,10 mm in diameter) was composed of three covered metallic pieces connected by surgical suture *** stent was collapsed by pulling the suture lines out of the *** weeks after stricture formation,endoscopic placement of a conventional stent or the new stent was *** extraction was carried out four weeks *** extraction rate,ease of extraction,migration,complications,and survival were ***:Stent migration occurred in 3/15(20%)animals in the control group and 2/15(13%) animals in the study group;the difference between the two groups was not statistically *** the end of four weeks,the remaining stents were successfully extracted with the endoscope in 100%(11/11) of the animals in the study group,and 60%(6/10)of the animals in the control group;this difference was statistically significant(P < 0.05).There was no difference in the mean number of follow-up days between the control and study groups(25.33 vs25.85).Minor bleeding was reported in five cases in the study group and four in the control *** were no severe complications directly associated with stent implantation or extraction in either of the two ***:In this experimental protocol of benign esophageal strictures,the novel "pieced" stent demonstrated a superior removal rate with a similar migration rate compared to a conventional stent.

摘要：通过对嵌入标准EESS#1中NTRUSign签名算法所采用的哈希函数进行结构剖析及其安全性分析,并在结构设计分析中指出了所采用哈希函数为二层迭代的MD结构,证明了哈希函数具有抗碰撞的安全性,但因其填充模块采用全零填充,导致存在伪造签名安全隐患.

摘要：复合材料飞轮储能系统结合了新材料技术、磁悬浮技术、高速可逆电机技术等,使得飞轮系统的储能密度大大提高,并引起了各国科技部门的高度关注。飞轮本体的结构和强度设计作为飞轮系统中的理论性的问题一直没有形成系统完整的分析方法,针对这一问题进行了概述,指出了现有模型的不足,为建立系统完整的复合材料飞轮强度设计方法提出了建议。

摘要：视觉文化表征下,"媚俗"成为必然的审美选择,人们自觉地与图像及图像制造的虚拟世界之间建立起一种精神生存的关系,作为视觉文化传播的重要艺术形态之一,电视剧遭遇着文化批判和审美实现的悖论。"视觉优先"趋势,一方面拓展和提升了电视剧艺术的叙述能力和美学感染力;另一方面又制造着一场场"泡沫式"的文化胜景。如何实现感性叙事形式和深层审美价值的契合,已成为电视视像艺术一个突出的文化与美学问题,不仅关系到其叙事话语所承载的价值意义所在,也关系着整个电视剧文化产业的生态发展。

摘要：本文考虑由一个原始制造商和一个独立再制造商构成的两阶段模型,原始制造商在第一阶段决策产品设计的可再制造性水平,再制造商在第二阶段进入产品市场并和原始制造商进行价格竞争.原始制造商可以通过改变产品设计的可再制造性水平来控制可再制造旧产品的供应数量.相对较高可再制造性水平的产品能够直接降低再制造商的生产成本,增加原始制造商的固定成本和新产品单位生产成本,降低政府征收的生产税.利用博弈论模型,我们得出了再制造不受回收数量约束和受回收数量约束两种情况下原始制造商和再制造商的均衡决策,得到了激励原始制造商选择生产高可再制造性新产品时政府生产税应该满足的条件,探讨了原始制造商和再制造商对于政府生产税变化的反应趋势,分析了均衡决策结果的敏感性,考虑了再制造产品均衡产量、再制造商均衡利润、原始制造商均衡利润关于参数变化百分比的反应趋势.