Traditional ultra-dense wireless networks are recommended as a complement for cellular networks and are deployed in partial areas, such as hotspot and indoor scenarios. Based on the massive ...multiple-input multi-output antennas and the millimeter wave communication technologies, the 5G ultra-dense cellular network is proposed to deploy in overall cellular scenarios. Moreover, a distribution network architecture is presented for 5G ultra-dense cellular networks. Furthermore, the backhaul network capacity and the backhaul energy efficiency of ultra-dense cellular networks are investigated to answer an important question, that is, how much densification can be deployed for 5G ultra-dense cellular networks. Simulation results reveal that there exist densification limits for 5G ultra-dense cellular networks with backhaul network capacity and backhaul energy efficiency constraints.
The fifth generation (5G) mobile communication systems will be in use around 2020. The aim of 5G systems is to provide anywhere and anytime connectivity for anyone and anything. Several new ...technologies are being researched for 5G systems, such as massive multiple-input multiple-output communications, vehicle-to-vehicle communications, high-speed train communications, and millimeter wave communications. Each of these technologies introduces new propagation properties and sets specific requirements on 5G channel modeling. Considering the fact that channel models are indispensable for system design and performance evaluation, accurate and efficient channel models covering various 5G technologies and scenarios are urgently needed. This paper first summarizes the requirements of the 5G channel modeling, and then provides an extensive review of the recent channel measurements and models. Finally, future research directions for channel measurements and modeling are provided.
Chalcogen bonding (ChB) has emerged as a promising tool in organic synthesis. However, compared with the well‐developed selenium‐ and tellurium‐based salt catalysts, the ChB catalysis of sulfonium ...salts is still unknown. Here, we report a new type of alkynyl‐sulfonium salt ChB catalysis for various ionic transformations, including transfer hydrogenation, bromination, bromolactonization, dimerization of 1,1‐diphenylethylene, nitro‐Michael addition reaction and Ritter reaction. More importantly, the photocapability of ChB was first demonstrated to generate alkynyl radicals for the synthesis of a variety of chalcogenoacetylenes. Mechanistic studies shed light on the mechanism of the photoinduced reactions and confirmed the involvement of alkynyl radicals which are difficult to generate otherwise.
Alkynyl sulfonium salts were employed as chalcogen bonding (ChB) catalysts for the first time. They display superior capability in the generation of alkynyl radicals under blue‐light irradiation.
Ligand enrichment assessment based on benchmarking data sets has become a necessity for the rational selection of the best‐suited approach for prospective data mining of drug‐like molecules. Up to ...now, a variety of benchmarking data sets had been generated and frequently used. Among them, MUBD‐HDACs from our prior research efforts was regarded as one of five state‐of‐the‐art benchmarks in 2017 by Frontiers in Pharmacology. This benchmarking set was generated by one of our unique de‐biasing algorithms. It also rendered quite a few other cases of successful applications in recent years, thus is expected to have more impact in modern drug discovery. To make our algorithm amenable to more users, we developed a Python GUI application called MUBD‐DecoyMaker 2.0. Moreover, it has two new additional functional modules, i. e. “Detect 2D Bias” and “Quality Control”. This new GUI version had been proved to be easy to use while generate benchmarking data sets of the same quality. MUBD‐DecoyMaker 2.0 is freely available at https://github.com/jwxia2014/MUBD‐DecoyMaker2.0, along with its manual and testcase.
ObjectiveNon-alcoholic fatty liver disease (NAFLD)-associated hepatocellular carcinoma (HCC) is an increasing healthcare burden worldwide. We examined the role of dietary cholesterol in driving ...NAFLD–HCC through modulating gut microbiota and its metabolites.DesignHigh-fat/high-cholesterol (HFHC), high-fat/low-cholesterol or normal chow diet was fed to C57BL/6 male littermates for 14 months. Cholesterol-lowering drug atorvastatin was administered to HFHC-fed mice. Germ-free mice were transplanted with stools from mice fed different diets to determine the direct role of cholesterol modulated-microbiota in NAFLD–HCC. Gut microbiota was analysed by 16S rRNA sequencing and serum metabolites by liquid chromatography–mass spectrometry (LC–MS) metabolomic analysis. Faecal microbial compositions were examined in 59 hypercholesterolemia patients and 39 healthy controls.ResultsHigh dietary cholesterol led to the sequential progression of steatosis, steatohepatitis, fibrosis and eventually HCC in mice, concomitant with insulin resistance. Cholesterol-induced NAFLD–HCC formation was associated with gut microbiota dysbiosis. The microbiota composition clustered distinctly along stages of steatosis, steatohepatitis and HCC. Mucispirillum, Desulfovibrio, Anaerotruncus and Desulfovibrionaceae increased sequentially; while Bifidobacterium and Bacteroides were depleted in HFHC-fed mice, which was corroborated in human hypercholesteremia patients. Dietary cholesterol induced gut bacterial metabolites alteration including increased taurocholic acid and decreased 3-indolepropionic acid. Germ-free mice gavaged with stools from mice fed HFHC manifested hepatic lipid accumulation, inflammation and cell proliferation. Moreover, atorvastatin restored cholesterol-induced gut microbiota dysbiosis and completely prevented NAFLD–HCC development.ConclusionsDietary cholesterol drives NAFLD–HCC formation by inducing alteration of gut microbiota and metabolites in mice. Cholesterol inhibitory therapy and gut microbiota manipulation may be effective strategies for NAFLD–HCC prevention.
Optical wireless communications (OWCs) refer to wireless communication technologies which utilize optical carriers in infrared, visible light, or ultraviolet bands of electromagnetic spectrum. For ...the sake of an OWC link design and performance evaluation, a comprehensive understanding and an accurate prediction of link behavior are indispensable. Therefore, accurate and efficient channel models are crucial for the OWC link design. This paper first provides a brief history of OWCs. It also considers OWC channel scenarios and their utilization trade-off in terms of optical carrier, range, mobility, and power efficiency. Furthermore, the main optical channel characteristics that affect the OWC link performance are investigated. A comprehensive overview of the most important OWCs channel measurement campaigns and channel models, primarily for wireless infrared communications and visible light communications, are presented. OWCs channel models are further compared in terms of computation speed, complexity, and accuracy. The survey considers indoor, outdoor, underground, and underwater communication environments. Finally, future research directions in OWCs channel measurements and models are addressed.
Five types of superparamagnetic iron oxide (SPIO), i.e. Ferumoxides (Feridex(®) IV, Berlex Laboratories), Ferucarbotran (Resovist(®), Bayer Healthcare), Ferumoxtran-10 (AMI-227 or Code-7227, ...Combidex(®), AMAG Pharma; Sinerem(®), Guerbet), NC100150 (Clariscan(®), Nycomed,) and (VSOP C184, Ferropharm) have been designed and clinically tested as magnetic resonance contrast agents. However, until now Resovist(®) is current available in only a few countries. The other four agents have been stopped for further development or withdrawn from the market. Another SPIO agent Ferumoxytol (Feraheme(®)) is approved for the treatment of iron deficiency in adult chronic kidney disease patients. Ferumoxytol is comprised of iron oxide particles surrounded by a carbohydrate coat, and it is being explored as a potential imaging approach for evaluating lymph nodes and certain liver tumors.
Abstract
With the background of fast developing artificial intelligence and Internet technology, face recognition, one of the product technologies under the theory of machine learning, has become ...widely applied on safety tests, identity confirmation, public security photos, and access control system. Based on the trend of its development speed, this technology will have well developed circumstances and the field of application will expand. One of the most essential reasons why it has become so popular is that the algorithms used for face recognition are advanced. In this paper, the author mainly researches five algorithms to realize face recognition based on relevant literature. They are separately CNN, PCA, SVM, MTCNN, and Facenet. After comparison and analysis, it can be found that CNN is one of the most suitable algorithms to recognize human faces, and PCA and SVM have problems of calculating speed. The use of complex neural networks can intensify the accuracy of face recognition just like MTCNN and Facenet. If combining different algorithms together and using their advantages in face recognition in different steps, the prediction of the algorithms will be better.
Tertiary enamides have long been thought of as stable and marginally valuable enamine variants in synthesis. This notion has been challenged, however, in recent years. Enabling the regulation of the ...cross-conjugation system of the tertiary enamides has been successfully shown to enhance delocalization of the nitrogen lone-pair electrons into a carbon-carbon double, thereby reinvigorating the enaminic reactivity of the tertiary enamides. In this article, I summarize the recent advances in the exploration of the nucleophilic reactions of tertiary enamides and their applications in the synthesis of natural products and heterocyclic compounds of biological and pharmaceutical relevance, with a primary focus on our own work.
Contrary to the general belief, tertiary enamides are reactive and unique synthons for the construction of diverse heterocycles of biological significance.
PDF
