Bioinspired synthesis and self-assembly of hybrid organic–inorganic nanomaterials

Nature is replete with complex organic–inorganic hierarchical materials of diverse yet specific functions. These materials are intricately designed under physiological conditions through biomineralization and biological self-assembly processes. Tremendous efforts have been devoted to investigating mechanisms of such biomineralization and biological self-assembly processes as well as gaining inspiration to develop biomimetic methods for synthesis and self-assembly of functional nanomaterials. In this work, we focus on the bioinspired synthesis and self-assembly of functional inorganic nanomaterials templated by specialized macromolecules including proteins, DNA and polymers. The in vitro biomineralization process of the magnetite biomineralizing protein Mms6 has been investigated using small-angle X-ray scattering. Templated by Mms6, complex magnetic nanomaterials can be synthesized on surfaces and in the bulk. DNA and synthetic polymers have been exploited to construct macroscopic two- and three-dimensional (2D and 3D) superlattices of gold nanocrystals. Employing X-ray scattering and spectroscopy techniques, the self-assembled structures and the self-assembly mechanisms have been studied, and theoretical models have been developed. Our results show that specialized macromolecules including proteins, DNA and polymers act as effective templates for synthesis and self-assembly of nanomaterials. These bottom-up approaches provide promising routes to fabricate hybrid organic–inorganic nanomaterials with rationally designed hierarchical structures, targeting specific functions

HSE management system and efficiency evaluation of construction projects

The strategy of Belt and Road Initiative actively advocates the establishment of economic partnerships with countries along the belt and road, and makes infrastructure construction a field for preferential development. It provides good development opportunities for domestic and foreign engineering contracting enterprises. The "Strategic Implementation Guidance Document" mentions that infrastructure construction and operation should be green and efficient. However, most state owned engineering contracting enterprises do not attach importance to HSE management, which obviously affects the engineering efficiency and hinders the sustainable development of enterprises. However, China's engineering contracting enterprises pay less attention to HSE management, which obviously affects project efficiency and hinders the sustainable develop ment of enterprises. This study takes a typical large project contracting enterprise (Enterprise A) in China as the research object, adopts the SWOT analysis method, analyzes the weakness of project management at the organization level, and consummates th e organization level project HSE management system of the enterprise at the organization layer and the project layer. Through the enterprise interview, questionnaire design and investigation, this study puts forward the suitable indicators and methods of H SE management performance evaluation, and verifies the effectiveness of the methods through the empirical analysis of eight projects. Then, this study proposes incorporating the project HSE management performance into the comprehensive evaluation methods o f project efficiency. The empirical analysis shows that the HSE management system proposed in this study at the organization layer and at the project layer can improve the HSE management performance of the project. Project HSE management performance has a positive impact on project efficiency, that is, the more enterprises attach importance to project HSE management, the higher the degree of completion of project objectives. The above research results are helpful to improve project management system at the organizational level and enhance the competitiveness of project contracting enterprises.A estratégia da "Belt and Road Initiative" defende ativamente o estabelecimento de parcerias económicas com os países ao longo de uma determinada faixa e faz da construção de infraestruturas um campo preferencial para desenvolvimento. Este campo fornece boas oportunidades de desenvolvimento para as empresas de engenharia nacionais e estrangeiras. O "Documento de Orientação de Implementação Estratégica" menciona que a construção e operação de infraestruturas deve ser eficiente e sustentável. No entanto, a grande maioria das empresas públicas contratadas não atribuem a devida importância aos sistemas de gestão de saúde e segurança (HSE) o que, obviamente, afecta a eficiência da engenharia e dificulta o desenvolvimento sustentável das empresas. As empresas privadas chinesas de engenharia ignoram a gestão HSE o que, obviamente, afecta, também, a eficiência dos projetos de sustentabilidade das empresas. Neste trabalho foi considerada uma grande empresa Chinesa de contratação (Empresa A) na China como referência de pesquisa, que adota a análise swot, analisa as fraquezas na gestão de projetos ao nível da organização e consuma a gestão de projetos em HSE ao nível da organização e do projeto em si. Através de entrevistas, questionários e investigação, este projeto apresenta os indicadores e métodos a dequados de avaliação de desempenho e verifica a efetividade dos métodos através da análise empírica de oito projetos. Em suma, este projeto propõe incorporar métodos de avaliação da eficiência através dos indicadores de gestão do HSE. A análise empírica demonstrou que o sistema proposto de gestão HSE, ao nível da organização e de projeto, pode aumentar efetivamente a gestão de performance do HSE em projeto. A gestão da performance do projeto HSE teve um impacto positivo na eficiência do projeto, ou seja, quanto mais as empresas atribuirem importância à gestão de projetos HSE maior será o nível de conclusão dos objetivos sustentáveis do projeto. Os resultados deste projeto são úteis para melhorar o sistema de gestão de projetos ao nível organizacional e aum entar a competitividade das empresas na contratação de projectos

Investigation and Exploration of ‘Student-Centered and Teacher-Led’ Teaching Model in English Medium Instruction (EMI) Calculus Course

The internationalization of higher education in China is constantly improving with an increasing level of diversification and globalization of education. High-level international English Medium Instruction (EMI) course is crucial to the cultivation of innovative international talents. Taking the Calculus course as an example, this article first demonstrates the importance and connotation of ‘know thy enemy and know yourself’ in the construction of EMI courses. Then it elaborates on the construction methods and significance of the ‘Leaning Community’, ‘Teaching Community’, and ‘Teaching-Learning Community’ through studies of the relationship between ‘teaching’ and ‘learning’ form the student-centered aspect. Such research provides a useful reference for the teaching model reform, especially the effective construction of EMI courses in non-native English-speaking countries

Polyethylene-Glycol-Mediated Self-Assembly of Magnetite Nanoparticles at the Liquid/Vapor Interface

It is shown that magnetite nanoparticles (MagNPs) grafted with polyethylene glycol (PEG) self‐assemble and short‐range‐order as 2D films at surfaces of aqueous suspensions by manipulating salt concentrations. Synchrotron X‐ray reflectivity and grazing‐incidence small angle X‐ray scattering studies reveal that K2CO3 induces the migration of the PEG‐MagNPs to the liquid/vapor interface to form a Gibbs layer of monoparticle in thickness. As the salt concentration and/or nanoparticle concentration increase, the surface‐adsorbed nanoparticles become more organized. And further increase in salt concentration leads to the growth of an additional incomplete nanoparticle layer contiguous to the first one at the vapor/liquid interface that remains intact

Numerical Investigation of Flow and Heat Transfer Characteristics in Plate with Multiple Incline Stage Holes

In this paper, the effects of impingement and film composite cooling on the design of combustion chamber cooling structure are simulated by numerical simulation. The focus of the investigation was on increased film cooling efficiency and enhanced heat transfer between the coolant and the hole wall. The five-stage shaped hole model and one cylindrical hole design have the same equivalent flow area. The flow and heat transfer characteristics of cylindrical hole and stage-shaped hole were numerically investigated under same blowing ratio, and compared at the same blowing ratio. The results showed the stage-shaped hole resulted in higher cooling effectiveness, especially in rear part, and the mechanisms of which were studied in details. The consequences of the phase parameters in the flow have very clearly dependedt on the internal shape of the corresponding hole. Stage-shaped holes formed impact inside the wall, tapped the coolant potential in cooling, and increased the heat transfer inside the solid wall. Further, stage-shaped hole resulted in unstabilized flow inside hole, gave an enhancement of lateral spreading ability, and brought a significant increase of the film lateral effectiveness. Further, the affection of area ratio and height ratio has been studied by five models. The results show that the increasing of area ratio leads to an increase in cooling efficiency, which also indicates the increasing of height ratio showed slight affection

Valence-programmable nanoparticle architectures.

Nanoparticle-based clusters permit the harvesting of collective and emergent properties, with applications ranging from optics and sensing to information processing and catalysis. However, existing approaches to create such architectures are typically system-specific, which limits designability and fabrication. Our work addresses this challenge by demonstrating that cluster architectures can be rationally formed using components with programmable valence. We realize cluster assemblies by employing a three-dimensional (3D) DNA meshframe with high spatial symmetry as a site-programmable scaffold, which can be prescribed with desired valence modes and affinity types. Thus, this meshframe serves as a versatile platform for coordination of nanoparticles into desired cluster architectures. Using the same underlying frame, we show the realization of a variety of preprogrammed designed valence modes, which allows for assembling 3D clusters with complex architectures. The structures of assembled 3D clusters are verified by electron microcopy imaging, cryo-EM tomography and in-situ X-ray scattering methods. We also find a close agreement between structural and optical properties of designed chiral architectures

Two-Dimensional Crystallization of Poly(N-isopropylacrylamide)-Capped Gold Nanoparticles

Surface-sensitive X-ray reflectivity and grazing incidence small-angle X-ray scattering reveal the structure of polymer-capped-gold nanoparticles (AuNPs that are grafted with poly(N-isopropylacrylamide); PNIPAM–AuNPs) as they self-assemble and crystallize at the aqueous suspension/vapor interface. Citrate-stabilized AuNPs (5 and 10 nm in nominal diameter) are ligand-exchanged by 6 kDa PNIPAM-thiol to form corona brushes around the AuNPs that are highly stable and dispersed in aqueous suspensions. Surprisingly, no clear evidence of thermosensitive effect on surface enrichment or self-assembly of the PNIPAM–AuNPs is observed in the 10–35 °C temperature range. However, addition of simple salts (in this case, NaCl) to the suspension induces migration of the PNIPAM–AuNPs to the aqueous surface, and above a threshold salt concentration, two-dimensional crystals are formed. The 10 nm PNIPAM–AuNPs form a highly ordered single layer with in-plane triangular structure, whereas the 5 nm capped NPs form short-range triangular structure that gradually becomes denser as salt concentration increases

Ionic depletion at the crystalline Gibbs layer of PEG-capped gold nanoparticle brushes at aqueous surfaces

In situ surface-sensitive x-ray diffraction and grazing incidence x-ray fluorescence spectroscopy (GIXFS) methods are combined to determine the ionic distributions across the liquid/vapor interfaces of thiolated-polyethylene-glycol–capped gold nanoparticle (PEG-AuNP) solutions. Induced by the addition of salts (i.e., Cs2SO4) to PEG-AuNPs solutions, two-dimensional hexagonal lattices of PEG-AuNPs form spontaneously at the aqueous surfaces, as is demonstrated by x-ray reflectivity and grazing incidence small-angle x-ray scattering. By taking advantage of element specificity with the GIXFS method, we find that the cation Cs+ concentration at the crystalline film is significantly reduced in parts of the PEG-AuNP film compared with that in the bulk