The structural stability of the developer collaboration network is critical to the success of the OSS (Open Source Software) community. However, research on the structural stability of the evolving ...developer collaboration network in OSS communities is relatively insufficient. In this paper, according to the software version sequence, we construct the corresponding developer collaboration network of the Angular OSS community and then analyse this network’s structural stability during network evolution. The results show that the network always presents an economical modular small-world structure during its evolution. The maintenance of the structure is related to a cohesive core, which is composed of two types of nodes (i.e., hubs and connectors). The hubs organize noncore nodes to form modules, while connectors facilitate the formation of inter-module connections. The overall results highlight the important role of core developers in the sustainable development of OSS communities and may provide a reference for community initiators to implement protection strategies for core developers.
The creation and use of big data have driven the intelligent development of e-commerce. The information generated in e-commerce provides a good means to analyze the behavior of users. How to use this ...information to give customer recommendations, improve the accuracy of recommendations and protect information security is a topic worth studying. For improving the accuracy of recommendations, analysis of users and tagging of resources are key. The current popular session recommendation algorithms face many problems, such as user interest drift which is difficult to be handled by these algorithms, thus affecting the recommendation accuracy. Based on these problems, this paper proposes a recommendation model based on deep learning, applies it to the clustering analysis of user tagging system, and designs a personalized recommendation algorithm for the tagging system. The model proposed in this paper can effectively analyze not only the interests exhibited by users in the current session, but also their potential long-term interests. By comparing the different performances of different datasets, the experimental results of this paper show that the proposed algorithmic model in this paper helps to dig the interests of different users, thus improving the quality of the recommendation system.
Graphene Quantum Dots for Optical Bioimaging Lu, Huiting; Li, Wenjun; Dong, Haifeng ...
Small (Weinheim an der Bergstrasse, Germany),
09/2019, Volume:
15, Issue:
36
Journal Article
Peer reviewed
Graphene quantum dots (GQDs) have shown great potential in bioimaging applications due to their excellent biocompatibility, low cytotoxicity, feasibility for surface functionalization, physiological ...stability, and tunable fluorescence properties. This Review first introduces the intriguing optical properties of GQDs that are suitable for biological imaging, and is followed by the GQDs' synthetic strategies. The emergent and latest development methods for tuning GQDs' optical properties are further described in detail. The recent advanced applications of GQDs in vitro, particularly in cell imaging, targeted imaging, and theranostic nanoplatform fabrication, are included. The applications of GQDs for in vivo bioimaging are also covered. Finally, the Review is concluded with the challenges and prospectives that face this nascent yet exciting field.
The intriguing optical properties of graphene quantum dots (GQDs) suitable for bioimaging are introduced and followed by the GQDs' synthetic strategies. The emergent and latest developed methods for tuning GQD optical properties and recent advanced bioimaging applications of GQD are further described in detail. The challenges and prospective that face this nascent yet exciting field are discussed.
The discovery of a novel aerobic oxidative intermolecular azide–zwitterion reaction catalyzed by an organocatalyst is presented. It is demonstrated that the merger of the Lewis base ...1,8‐diazabicyclo5.4.0undec‐7‐ene and electron‐deficient olefins generates reactive zwitterion intermediates, which readily participate in cycloaddition reactions with an array of azides, thus providing facile entry to fully or highly substituted 1,2,3‐triazole frameworks. The reaction features an excellent substrate scope, and the products are obtained with high yields and excellent regioselectivities. It is demonstrated that some of these products can be transformed into pharmaceutically important agents. In addition to the experimental results, a detailed mechanistic survey is also provided, including MS studies rationalizing the origin of regioselective control.
The works: The discovery of a novel aerobic oxidative intermolecular azide–zwitterion reaction catalyzed by an organocatalyst is presented. It is demonstrated that the merger of the Lewis base 1,8‐diazabicyclo5.4.0undec‐7‐ene (DBU) and electron‐deficient olefins generates reactive zwitterion intermediates, which readily participate in cycloaddition reactions with an array of azides, thus providing facile entry to fully or highly substituted 1,2,3‐triazole frameworks.
In recent years, photocatalytic technologies have been extensively studied and diffusely used in water splitting, decomposition of organic pollutants, reduction of carbon dioxide, etc. As a type of ...eye-catching semiconductors, BiVO4, Bi2WO6, and Bi2MoO6 (denoted as BiaAOb) have become a hotspot in photocatalytic researches due to their crystal structure stability, high light quantum and electronic transmission efficiency, and outstanding energy utilization capacity. However, pristine BiaAOb (A = V, W, and Mo) possesses several drawbacks, such as low separation efficiency of photo-excited electron-hole pairs, low specific surface area, as well as the poor quantum utilization, which restrict their photocatalytic performance. Considerable efforts, such as nanostructure modification, surface engineering, and heterojunction/homojunction fabrication, have been conducted to solve these problems. This integrated review aims to sum up recent advances in current studies on fabrication of high efficiency BiaAOb photocatalysts to accelerate the developments of BiaAOb-based materials in the photocatalysis (PC) field. The current challenges and prospects of BiaAOb are emphasized which stretches the existing fundamental theories of PC as well as provide a promising strategy to fabricate high efficiency BiaAOb catalysts to control environmental pollution and assist the sustainable development of energy.
Based on the empirical data on the development of special economic zones in countries with developed and developing economies, this article illustrates the positive effect of the state regional ...development policy and confirms the effectiveness of the technology under study. The purpose of this article is to determine the essence of the Economic and Technological Development Zones and to identify their main characteristics. To achieve this goal, a systematic review was chosen as a research method using the meta-analysis method, in accordance with which a selective study of 76 publications included in the free search engine for scientific publications was carried out, within which, according to the selected criteria for the structure of the article, the age of the source, the presence in the keywords of the research object as well as the availability of the results of theoretical and empirical analysis, 26 publications were selected, the meta-analysis of which made it possible to identify the essential properties and characteristics of the category Economic and Technological Development Zone. The main condition for the successful implementation of the Development Zones project is the creation of industrial symbiosis, taking into account the environmental aspect and the adaptation of the Development Zone strategies to the institutional conditions of specific countries and regions.
Airborne fibers are of public concern because of their potential threat to the environment, however their physical and chemical properties are poorly understood. Fibers are defined as having an ...aspect ratio >3:1. Fiber particles were collected in the near surface air, surface deposited dust and building materials in Beijing. They were examined using analytical scanning electron microscopy. The particles were initially classified into two categories: organic and inorganic. Organic fibers comprised microplastic and natural organic fiber particles. Inorganic fibers were mainly man-made mineral fibers (MMMFs), asbestos (represented by chrysotile), calcium sulfate and metal fiber particles. Microplastic and MMMFs fibers were most abundant, accounting for 34.6% and 40.3% in total, respectively, followed by asbestos (7.8%), calcium sulfate (7.2%), metal fibers (5.6%) and natural organic fiber particles (4.5%). The number-concentration of these particles was about 16.7 × 10−3 fibers/ml at 1.5 m above the ground and about 14.1 × 10−3 fibers/ml at about 18 m, suggesting the particles were mainly derived from surface and were re-suspended. Approximately 80% of the airborne fiber were smaller than 20 μm in length, which is possibly the critical size for fiber particles to re-suspend into the air. Surface dust and construction sites were speculated to be the major contributors of the fiber particles.
Display omitted
•Airborne fiber particles were detected in the urban atmosphere.•Microplastic and man-made mineral fibers predominate the airborne fiber particles.•Approximately 80% of fiber particles were smaller than 20 μm in length.•Plastics, construction and industrial materials contribute to the airborne fiber particles.
Economic, policy, and climate changes have profoundly influenced pastoral social-ecological systems on the Tibetan Plateau. Climate change is believed to be leading to increasing extreme weather ...conditions such as snow disasters and droughts, putting a strain on the rangeland resources herders must have to increase income. Market-based economic reforms and interrelated development policies such as the Rangeland Household Contract Policy, the Ecological Construction Project, and herder settlement Initiatives have increased integration of pastoral regions into modern markets with promotion of tourism, expanded livestock markets, and marketing opportunities for rangeland resources. Although allocating common rangelands to households is the foundation of current rangeland management strategies to achieve these goals, it removes important technologies for coping with high variability in rangeland forage production from the traditional rangeland management portfolio on the Tibetan Plateau. These include shared risk, shared labor, seasonal and yearly herd mobility, and access to diverse areas of rangelands and multiple water sources. Field study of two villages in Guinan County of Qinghai Province, and Ruoergai County of Sichuan Province from 2011 to 2014 found that the villages responded to externally driven policy, economic, and climate changes with an innovative locally adapted quota-based grazing management system that preserves valuable management technologies, conserves rangeland resources, and provides individual opportunities for financial gain. In this way the village social-ecological system has exhibited considerable resiliency, maintaining a form of community governance that functions to manage the rangelands, improve well-being as indicated by livestock productivity, and, according to local perceptions, maintain rangeland condition. The community-based grazing quota system devised by the villages occupies a middle ground between common and individual models for resource use because it focuses more on how to equitably distribute services and utilities from rangelands, instead of how to distribute rangelands.
PDF
