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211.
《International Journal of Hydrogen Energy》2022,47(17):9925-9933
In recent years, tremendous efforts have been devoted to develop new photocatalyst with wide spectrum response for H2 generation from water or aqueous solution. In this paper, MnxCd1-xS composites were in-situ fabricated via the high-temperature sulfurization to enhance the solar-light photocatalytic capacity of H2 evolution. Benefiting from the S defects and junction interface between MnS and CdS, MnxCd1-xS composites exhibited the better H2 evolution rate than pure MnS. The H2 evolution rate of optimal Mn0.5Cd0.5S with a Mn(II) content of 22.52% and a Mn/Cd mole ratio of 0.95:1 was 9.27 mmol g?1 h?1, which was 35.65 and 2.38 times higher than pure MnS (0.26 mmol g?1 h?1) and CdS (3.89 mmol g?1 h?1), respectively. In addition, H2 evolution capacity of Mn0.5Cd0.5S decreased from 44.83 to 41.66 mmol g?1 after three cycles. Mn0.5Cd0.5S prepared via the high-temperature sulfurization was thus a potential material for solar-light induced H2 generation. 相似文献
212.
《Journal of Great Lakes research》2022,48(5):1288-1297
Beginning in 2013, sites at the 128-m bottom depth contour were added to the sampling design of the annual Lake Michigan bottom trawl survey for prey fish, which has been conducted by the U.S. Geological Survey Great Lakes Science Center (GLSC) each fall since 1973, to better assess fish depth distributions in a changing ecosystem. The standard sampling design included bottom depths from 9 to 110 m, although the GLSC also sporadically conducted bottom trawl tows at the 128-m bottom depth contour during 1973–1988. Enactment of this new sampling design in 2013 revealed that mean biomass density of deepwater sculpins (Myoxocephalus thompsonii) at the 128-m depth exceeded the sum of mean biomass densities at shallower depths, indicating that the bulk of the deepwater sculpin population is residing in waters deeper than 110 m. Thus, our findings supported the hypothesis that the depth distribution of the deepwater sculpin population had shifted to deeper waters beginning in 2007, thereby explaining, at least in part, the marked decline in deepwater sculpin abundance since 2006 based on the standard sampling design. In contrast, our results did not support the hypothesis that the slimy sculpin (Cottus cognatus) population had shifted to deeper waters sometime after 2000. A portion of the burbot (Lota lota) population may have also shifted in depth distribution to waters deeper than 110 m after 2007, based on our results. Our findings have served as an impetus to further expand the range of depths sampled in our bottom trawl survey. 相似文献
213.
《International Journal of Hydrogen Energy》2021,46(74):36848-36858
In2S3-NiS co-decorated MoO3@MoS2 (INS/MoO3@MoS2) heterojunctions were prepared in nonthermal plasma via the in-situ sulfurization for enhancing the solar-light photocatalytic conversion of CO2 into CH4 and CO at 423 K. In contrast with hexagonal h-MoO3 nanorods, CH4 and CO yields were enhanced by h-MoO3@MoS2 and In2S3/MoO3@MoS2, while the increased CH4 yield and decreased CO yield were obtained by INS/MoO3@MoS2 and NiS/MoO3@MoS2. The optimal 3-INS/MoO3@MoS2 with a nominal NiS-In2S3 content of 5.0 wt% and a In/Ni molar ratio of 2:1 exhibited the best photoreduction activity of CO2, of which CH4 and CO yields were 49.11 and 6.19 μmol g−1 h−1, respectively. It's ascribed to the tight interface for enhancing the visible-light absorption capacity and reinforcing the transfer and separation of charge carriers. S-rich sites and O vacancies were favorable for the adsorption and photoreduction of reactants on the bulks surface. The nonthermal plasma induced in-situ sulfurization was thus a promising route to fabricate metal sulfides-based heterojunctions. 相似文献
214.
《International Journal of Hydrogen Energy》2020,45(28):14334-14346
Developing low-cost, highly efficient and robust photocatalystic hydrogen evolution system is a promising solution to environmental and energy crisis. Herein, a Z-scheme Cu3P/ZnIn2S4 heterojunction photocatalyst was successfully constructed for the first time via a facile solution-phase hybridization method. The optimized Cu3P/ZIS composite exhibited the highest H2 production rate of 2561.1 μmol g−1 h−1 under visible light irradiation (>420 nm), which was 5.2 times greater than that of bare ZnIn2S4 and even exceeded the photocatalytic performance of Pt/ZIS composite. The apparent quantum yield of 10 wt% Cu3P/ZnIn2S4 can reach 22.3% at 420 nm. The huge boost of photocatalytic hydrogen evolution activity is ascribed to the formation of heterojunction with the built in electric field within Cu3P/ZnIn2S4 and Z-scheme charge carriers transfer pathway, which result in efficient separation and migration of charge carriers. In addition, both experimental and theoretical calculation confirmed that the charge-carriers transfer pathway of Cu3P/ZnIn2S4 photocatalyst follows the Z-scheme mechanism instead of conventional type-Ⅱ heterojunction mechanism. This work is considered helpful for getting a great deal of insight into constructing high-activity and cost-effective transition metal phosphides (TMPs) based photcatalytic hydrogen production system and rationally designing Z-scheme heterojunction photocatalyst. 相似文献
215.
《International Journal of Hydrogen Energy》2019,44(52):28252-28261
In this work we present rubidium hydrazinidoborane RbN2H3BH3 (RbHB), the newest and last member of the alkali metal derivatives of hydrazine borane N2H4BH3 (HB). It is shown that HB readily reacts with metallic rubidium in THF at room temperature to form RbHB under argon atmosphere. The molecular and crystal structures of this new compound are discussed on the basis of FTIR spectroscopy, 11B MAS NMR spectroscopy, and powder X-ray diffraction analyses. RbHB crystallizes in a monoclinic P21 (No. 4) unit cell where each Rb+ cation adopts octahedral coordination surrounded by six [N2H3BH3]− anions, which are two more than for e.g. LiN2H3BH3 (with tetrahedral coordination) in accordance with the larger size of Rb+. RbHB is isostructural to potassium hydrazinidoborane KN2H3BH3. Its dehydrogenation properties, evaluated by using thermogravimetric analysis, differential scanning calorimetry, and isothermal analysis, are compared to those of the parent HB as well as to analogous compounds in order to evaluate the potential of RbHB as hydrogen storage material. According to the presented data, the dehydrogenation properties of RbHB are much better than those of HB and are comparable to those of the lithium derivative. Our main results are reported therein. 相似文献
216.
As the combine of cloud computing and Internet breeds many flexible IT services,cloud computing becomes more and more significant.In cloud computing,a user should be authenticated by a trusted third party or a certification authority before using cloud applications and services.Based on this,a protocol composition logic (PCL) secure user authentication protocol named UCAP for cloud computing was proposed.The protocol used a symmetric encryption symmetric encryption based on a trusted third party to achieve the authentication and confidentiality of the protocol session,which comprised the initial authentication phase and the re-authentication phase.In the initial authentication phase,the trusted third party generated a root communication session key.In the re-authentication phase,communication users negotiated a sub session key without the trusted third party.To verify the security properties of the protocol,a sequential compositional proof method was used under the protocol composition logic model.Compared with certain related works,the proposed protocol satisfies the PCL security.The performance of the initial authentication phase in the proposed scheme is slightly better than that of the existing schemes,while the performance of the re-authentication phase is better than that of other protocols due to the absence of the trusted third party.Through the analysis results,the proposed protocol is suitable for the mutual authentication in cloud computing. 相似文献
217.
218.
藏文音节拼写检查是藏语自然语言处理的基本任务,在藏文文字处理、文字识别、文本生成等领域具有广泛的应用。该文首先针对藏文音节的结构提出了音节向量化的方法,即音节矩阵。然后构建了适合于藏文音节拼写检查的CNN模型,使用1 364 880个藏文音节进行训练。最后对68 244个藏文音节进行测试。实验结果显示,藏文音节拼写检查CNN模型的结果优于规则、RNN和LSTM等模型,不仅对符合藏文文法的音节能正确识别外,而且对梵音藏文音节也能有效识别,正确率、召回率以及F值分别为99.52%、99.30%和99.41%。 相似文献
219.
220.
藏语是语序非常灵活的一种语言,藏语词法分析和句法分析等浅层研究不能很好地满足藏语自然语言理解的需求。从简单句型的藏语句子出发,研究了基于投射的藏语语义依存分析,构建了藏语语义依存树库,设计了语义依存弧类型分析特征模板。最后通过最大熵分类模型,对人工分析过的语义依存弧的句子进行依存弧的类型分析并进行标注,为今后的语义依存分析提供新的思考视角和更好的理论支撑。 相似文献