Chan‐Lam reactions hold promise as one of the most efficient synthetic methods to construct various carbon‐heteroatom or carbon‐carbon bonds. Recently, a series of Chan‐Lam reactions were developed ...to boost organic synthesis. Herein, we summarized the latest research and progress of Chan‐Lam coupling to illustrate its synthetic value.
In the present article, we investigate the following Hénon-Lane-Emden elliptic system:
where
,
,
,
,
. We partially prove the Hénon-Lane-Emden conjecture in the case of four and five dimensions. More ...specifically, we show that there is no nonnegative nontrivial classical solution for the Hénon-Lane-Emden elliptic system when
,
and the parameter pair (
) meets
and additionally
if
or
if
Metabolic diseases are serious threats to public health and related to gut microbiota. Probiotics, prebiotics, synbiotics, and postbiotics (PPSP) are powerful regulators of gut microbiota, thus ...possessing prospects for preventing metabolic diseases. Therefore, the effects and mechanisms of PPSP on metabolic diseases targeting gut microbiota are worth discussing and clarifying. Generally, PPSP benefit metabolic diseases management, especially obesity and type 2 diabetes mellitus. The underlying gut microbial-related mechanisms are mainly the modulation of gut microbiota composition, regulation of gut microbial metabolites, and improvement of intestinal barrier function. Moreover, clinical trials showed the benefits of PPSP on patients with metabolic diseases, while the clinical strategies for gestational diabetes mellitus, optimal formula of synbiotics and health benefits of postbiotics need further study. This review fully summarizes the relationship between probiotics, prebiotics, synbiotics, postbiotics, and metabolic diseases, presents promising results and the one in dispute, and especially attention is paid to illustrates potential mechanisms and clinical effects, which could contribute to the next research and development of PPSP.
The wide application of “Internet+” makes the organic integration of accounting and cloud computing a trend, and cloud accounting is also favored by enterprises for its efficient information sharing ...and high scalability; however, in the actual promotion due to the openness of the Internet and other special reasons, it also reveals such problems and risks as confusion in choosing cloud services, confusion in service level agreement, confusion in system irregularities and insufficient legal compliance. This paper takes the risk of transmission, storage, and use of financial information in the process of applying cloud accounting in manufacturing enterprises as the research object, to identify, confirm and evaluate the risk factors of cloud accounting and propose counter strategies. The results show that the relationship between the risk factors of cloud accounting are: risk of decision making in applying cloud services > risk of data information security > risk caused by insufficient understanding of service level agreement > risk of system Therefore, the risk of using cloud accounting in manufacturing enterprises is moderate and controllable, and as long as the risk factors are controlled reasonably, the use of cloud accounting is beneficial to the development of manufacturing enterprises.
When the coronavirus disease 2019 (COVID-19) outbreak became paramount, medical care for other devastating diseases was negatively impacted. In this study, we investigated the impact of the COVID-19 ...outbreak on stroke care across China.
Data from the Big Data Observatory Platform for Stroke of China consisting of 280 hospitals across China demonstrated a significant drop in the number of cases of thrombolysis and thrombectomy. We designed a survey to investigate the major changes during the COVID-19 outbreak and potential causes of these changes. The survey was distributed to the leaders of stroke centers in these 280 hospitals.
From the data of Big Data Observatory Platform for Stroke of China, the total number of thrombolysis and thrombectomy cases dropped 26.7% (
<0.0001) and 25.3% (
<0.0001), respectively, in February 2020 as compared with February 2019. We retrieved 227 valid complete datasets from the 280 stroke centers. Nearly 50% of these hospitals were designated hospitals for COVID-19. The capacity for stroke care was reduced in the majority of the hospitals. Most of the stroke centers stopped or reduced their efforts in stroke education for the public. Hospital admissions related to stroke dropped ≈40%; thrombolysis and thrombectomy cases dropped ≈25%, which is similar to the results from the Big Data Observatory Platform for Stroke of China as compared with the same period in 2019. Many factors contributed to the reduced admissions and prehospital delays; lack of stroke knowledge and proper transportation were significant limiting factors. Patients not coming to the hospital for fear of virus infection was also a likely key factor.
The COVID-19 outbreak impacted stroke care significantly in China, including prehospital and in-hospital care, resulting in a significant drop in admissions, thrombolysis, and thrombectomy. Although many factors contributed, patients not coming to the hospital was probably the major limiting factor. Recommendations based on the data are provided.
Two-dimensional (2D) van der Waals (vdW) magnetic materials have recently been introduced as a new horizon in materials science, and they enable potential applications for next-generation spintronic ...devices. Here, in this communication, the observations of stable Bloch-type magnetic skyrmions in single crystals of 2D vdW Fe3GeTe2 (FGT) are reported by using in situ Lorentz transmission electron microscopy (TEM). We find the ground-state magnetic stripe domains in FGT transform into skyrmion bubbles when an external magnetic field is applied perpendicularly to the (001) thin plate with temperatures below the Curie temperature T C. Most interestingly, a hexagonal lattice of skyrmion bubbles is obtained via field-cooling manipulation with magnetic field applied along the 001 direction. Owing to their topological stability, the skyrmion bubble lattices are stable to large field-cooling tilted angles and further reproduced by utilizing the micromagnetic simulations. These observations directly demonstrate that the 2D vdW FGT possesses a rich variety of topological spin textures, being of great promise for future applications in the field of spintronics.
Porous infill structures have been widely studied and used in additive manufacturing because of their lightweight and excellent mechanical properties. However, without considering graded ...multi-material infill pattern, existed infill design methods have not yet fully tapped the potential of multiple materials in structural design. In this paper, a systematic multi-phase infill design method is proposed to generate graded multi-material infill structures. The method builds upon a unified multi-material density-based topology optimization framework, in which a modified multi-phase material interpolation formulation is presented to represent the relationship between the stiffness matrix and design variables. To generate spatial-varying and multi-phase structures distributed in the interior of a design domain, the maximum local material volume constraints are imposed on each phase material in the neighborhood of each element in the design domain. A series of relaxations is introduced into the framework to facilitate the implementation of the gradient-based optimization algorithm. The whole design process is performed on a full-size finite element analysis, so it can avoid the separation of scales and naturally guarantee the optimized infills to be smoothly connected. The applicability and effectiveness of the proposed multi-phase infill generation model are then demonstrated by several typical numerical examples with the objective of minimum compliance.
•A novel design method for spatially-varying multi-phase infill structures.•The method avoids the length scale separation and sub-structure connectivity issue.•A unified multi-material topology optimization framework is presented.•The approach of imposing local volume constraints on multiphase materials is developed.•The advantages of the obtained graded multi-phase infill structures are demonstrated.
Biosynthetic pathways without any identifiable core enzymes may encode unknown (biosynthetic route)–unknown (molecular structure) natural products. However, bioinformatics-guided mining for such ...unknown-unknown metabolites is challenging. Recently, an unknown-unknown biosynthetic route has been deciphered in fungi. It was found that a class of enzymes previously annotated as hypothetical proteins catalyze the biosynthesis of arginine-containing cyclodipeptides (CDPs). This advances the understanding of the biosynthesis of CDPs and highlights the vast potential of unknown-unknown natural products encoded by microbial genomes.
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