68 research outputs found

    Structural Engineering of Hierarchical Micro‐nanostructured Ge-C Framework by Controlling the Nucleation for Ultralong Life Li Storage

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    The rational design of a proper electrode structure with high energy and power densities, long cycling lifespan, and low cost still remains a significant challenge for developing advanced energy storage systems. Germanium is a highly promising anode material for high-performance lithium ion batteries due to its large specific capacity and remarkable rate capability. Nevertheless, poor cycling stability and high price significantly limit its practical application. Herein, a facile and scalable structural engineering strategy is proposed by controlling the nucleation to fabricate a unique hierarchical micro-nanostructured Ge-C framework, featuring high tap density, reduced Ge content, superb structural stability, and a 3D conductive network. The constructed architecture has demonstrated outstanding reversible capacity of 1541.1 mA h g −1 after 3000 cycles at 1000 mA g −1 (with 99.6% capacity retention), markedly exceeding all the reported Ge-C electrodes regarding long cycling stability. Notably, the assembled full cell exhibits superior performance as well. The work paves the way to constructing novel metal-carbon materials with high performance and low cost for energy-related applications

    Wireless sensor network system for indoor air quality supervision

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    U okviru diplomskog rada razvijen je sustav nadzora kvalitete zraka u zatvorenim prostorima. Sustav je razvijen koristeći koncept bežične senzorske mreže. Sustav prikuplja podatke s terena čiji su izvori senzorski čvorovi, a ponori distribuirane instance korisničke aplikacije. Senzorska mreže u konačnici prikuplja podatke o: • zadimljenosti prostorije, • količini lebdećih čestica u zraku, • grubu detekciju količine štetnog plina u prostoriji, • mjerenje temperature i • iznos relativne vlažnosti zraka. Senzorski čvorovi raspoređeni su u promatranom objektu, a prikupljeni podaci su proslijeđeni centralnom poslužitelju. Centralni poslužitelj je realiziran Internet aplikacijom. U okviru rada obrađene su osnove kakvoće zraka, zatim je opisan osnovni princip definiranja sustava (bežične senzorske mreže) s predloškom za izvedbu zadanog sustava. Obrađene su potrebne jedinice, među kojima su senzori za mjerenje potrebnih fizikalnih veličina, bežični komunikacijski moduli i mikroupravljački uređaji. Opisana je priprema okoline i konfiguracije, primjerice na usmjerniku za definiranu funkcionalnost prenošenja podataka iz senzorske mreže do korisničke aplikacije. Opisana je izrada korisničke aplikacije čime je dovršena izrada funkcionalnosti sustava. U konačnici izvedena su mjerenja prijema paketa kako bi se doznala ograničenja sustava, vezana uz domet i strategiju postavljanja komunikacijskih čvorova. U zaključku su predložena moguća unapređenja postojećeg rješenja ili mogućnosti prenamjene sustava.This thesis goes through a study and a practical development of a system of indoor air quality management. Indoor air quality management system is been developed with the wireless sensor network concept in its focus. This system is capable of collecting data from a distributed network of sensor nodes. Visualization of data is made by a service of user applications which are distributed to network clients. Sensor network collects data about: • amount of smoke in an object, • amount of particle matter in the air of an object, • approximation on the amount of harmful gas or gases in the object, • current temperature, • and amount of relative humidity. Sensor nodes are deployed to a selected complex, collected data is been forwarded to a central server. Server is implemented as a web application. Thesis elaborates the basic principle of defining the system (of wireless sensor networks) with its model for the performance measurement. Study on all necessary components is been presented, including sensors, wireless modules and microcontrollers. Basic settings and preparation of the environment is been defined, e.g. for the functionality of relaying data from sensor network to the user application. Afterwards, one can find notations on a development of the user application which completes the functionality of the proposed system. Finally, measurement are been presented on the packet reception rate, which can indicate on the limitations of the system doe to the propagation of packets in indoor environment. Measurement can be used as a indication for strategies on setting up network configuration and node distribution. In the conclusion there are proposed improvements for the selected solution or possibilities of functionality conversion

    Gains to Chinese Bidder Firms::Domestic vs. Foreign Acquisitions

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    This paper examines whether foreign acquisition of Chinese firms improves share price performance relative to domestic acquisitions. The results show that foreign acquisitions are not associated with positive abnormal returns in the short-run, but that they are so associated for domestic acquisitions. Foreign acquisitions also realise significant long-run gains, especially when the acquiring firm is large. Specifically, we find that there is a significant, positive long-run outperformance of 29.81% for large foreign acquisitions benchmarked against domestic ones, while large foreign acquisitions earn 22.39% in aggregate. Our evidence suggests that large Chinese acquirers gain when they expand their operations abroad, consistent with the literature on reverse internalisation

    Examining the generalizability of research findings from archival data

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    This initiative examined systematically the extent to which a large set of archival research findings generalizes across contexts. We repeated the key analyses for 29 original strategic management effects in the same context (direct reproduction) as well as in 52 novel time periods and geographies; 45% of the reproductions returned results matching the original reports together with 55% of tests in different spans of years and 40% of tests in novel geographies. Some original findings were associated with multiple new tests. Reproducibility was the best predictor of generalizability—for the findings that proved directly reproducible, 84% emerged in other available time periods and 57% emerged in other geographies. Overall, only limited empirical evidence emerged for context sensitivity. In a forecasting survey, independent scientists were able to anticipate which effects would find support in tests in new samples

    Professional knowledge development of bilingual teacher-researchers : a self-study of making Chinese learnable

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    This study focuses on the potential effects of self-study on the professional knowledge development of a bilingual teacher-researcher at the beginning of her career. To fully understand the significance of this inquiry, three contributory research questions were addressed: (1) How can self-study contribute to the bilingual teacher-researcher’s professional knowledge development in knowing students, and how they learn? (2) How can self-study contribute to the bilingual teacher-researcher’s professional knowledge development in knowing the content of Chinese and how to teach it? (3) How will professional knowledge development in cross cultural exchanges contribute to Australian school students’ learning of Chinese language and culture? As a part of the Research Oriented School Engaged Teacher-researcher Education (ROSETE) Program, the author underwent Chinese teaching experience over a period of one and a half years in a local Australian public high school. Regarding the self-study research, data were collected from surveys and quizzes of students, and interviews, audio recordings, and observation sheets from head teachers and ROSETE colleagues, as well as self-reflection journals. The findings indicate that self-study is an efficient way to develop the bilingual teacher-researcher’s professional knowledge at the beginning of the career, and for understanding students and the way they learn. In addition, this method not only contributes to the teacher-researcher’s improvement in comprehending content, but also offers an optimal way to deliver knowledge to students. More importantly, this study suggests that advanced professional knowledge in cross cultural exchange and communication can have a significantly positive effect on teaching and helping Australian school students to learn Chinese language and culture

    γ-Aminobutyric Acid Priming Alleviates Acid-Aluminum Toxicity to Creeping Bentgrass by Regulating Metabolic Homeostasis

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    Aluminum (Al) toxicity is a major limiting factor for plant growth and crop production in acidic soils. This study aims to investigate the effects of γ-aminobutyric acid (GABA) priming on mitigating acid-Al toxicity to creeping bentgrass (Agrostis stolonifera) associated with changes in plant growth, photosynthetic parameters, antioxidant defense, key metabolites, and genes related to organic acids metabolism. Thirty-seven-old plants were primed with or without 0.5 mM GABA for three days and then subjected to acid-Al stress (5 mmol/L AlCl3·6H2O, pH 4.35) for fifteen days. The results showed that acid-Al stress significantly increased the accumulation of Al and also restricted aboveground and underground growths, photosynthesis, photochemical efficiency, and osmotic balance, which could be effectively alleviated by GABA priming. The application of GABA significantly activated antioxidant enzymes, including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, to reduce oxidative damage to cells under acid-Al stress. Metabolomics analysis demonstrated that the GABA pretreatment significantly induced the accumulation of many metabolites such as quinic acid, pyruvic acid, shikimic acid, glycine, threonine, erythrose, glucose-6-phosphate, galactose, kestose, threitol, ribitol, glycerol, putrescine, galactinol, and myo-inositol associated with osmotic, antioxidant, and metabolic homeostases under acid-Al stress. In addition, the GABA priming significantly up-regulated genes related to the transportation of malic acid and citric acid in leaves in response to acid-Al stress. Current findings indicated GABA-induced tolerance to acid-Al stress in relation to scavenging of reactive oxygen species, osmotic adjustment, and accumulation and transport of organic metabolites in leaves. Exogenous GABA priming could improve the phytoremediation potential of perennial creeping bentgrass for the restoration of Al-contaminated soils

    Health Risk and Resilience Assessment with Respect to the Main Air Pollutants in Sichuan

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    Rapid urbanization and industrialization in developing countries have caused an increase in air pollutant concentrations, and this has attracted public concern due to the resulting harmful effects to health. Here we present, through the spatial-temporal characteristics of six criteria air pollutants (PM2.5, PM10, SO2, NO2, CO, and O3) in Sichuan, a human health risk assessment framework conducted to evaluate the health risk of different age groups caused by ambient air pollutants. Public health resilience was evaluated with respect to the risk resulting from ambient air pollutants, and a spatial inequality analysis between the risk caused by ambient air pollutants and hospital density in Sichuan was performed based on the Lorenz curve and Gini coefficient. The results indicated that high concentrations of PM2.5 (47.7 μg m−3) and PM10 (75.9 μg m−3) were observed in the Sichuan Basin; these two air pollutants posed a high risk to infants. The high risk caused by PM2.5 was mainly distributed in Sichuan Basin (1.14) and that caused by PM10 was principally distributed in Zigong (1.01). Additionally, the infants in Aba and Ganzi had high health resilience to the risk caused by PM2.5 (3.89 and 4.79, respectively) and PM10 (3.28 and 2.77, respectively), which was explained by the low risk in these two regions. These regions and Sichuan had severe spatial inequality between the infant hazard quotient caused by PM2.5 (G = 0.518, G = 0.493, and G = 0.456, respectively) and hospital density. This spatial inequality was also caused by PM10 (G = 0.525, G = 0.526, and G = 0.466, respectively), which is mainly attributed to the imbalance between hospital distribution and risk caused by PM2.5 (PM10) in these two areas. Such research could provide a basis for the formulation of medical construction and future air pollution control measures in Sichuan
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