157 research outputs found

    Design and synthesis of a new mannitol stearate ester-based aluminum alkoxide as a novel tri-functional additive for poly(vinyl chloride) and its synergistic effect with zinc stearate

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    Thermal stabilizers, lubricant, and plasticizers are three crucial additives for processing poly(vinyl chloride) (PVC). In this study, a new mannitol stearate ester-based aluminum alkoxide (MSE-Al) was designed and synthesized as a novel additive for PVC. The thermal stability and processing performance of PVC stabilized by MSE-Al were evaluated by the Congo red test, conductivity measurement, thermal aging test, ultravioletevisible (UV–Vis) spectroscopy test, and torque rheometer test. Results showed that the addition of MSE-Al could not only markedly improve the long-term thermal stability of PVC, but also greatly accelerate the plasticizing and decrease the balance torque, which demonstrated that MSE-Al possessed a lubricating property. Thus, MSE-Al was demonstrated to be able to provide tri-functional additive roles, e.g., thermal stabilizer, plasticizer, and lubricant. The test results for the thermal stability of PVC indicated that the initial whiteness of PVC stabilized by MSE-Al was not good enough, thus the synergistic effect of MSE-Al with zinc stearates (ZnSt2) on the thermal stability of PVC was also investigated. The results showed that there is an appreciable synergistic effect between MSE-Al and ZnSt2. The thermal stabilization mechanism and synergism effect of MSE-Al with ZnSt2 are then discussed

    Comparison of the fecal microbiota of two free-ranging Chinese subspecies of the leopard (Panthera pardus) using high-throughput sequencing

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    The analysis of gut microbiota using fecal samples provides a non-invasive approach to understand the complex interactions between host species and their intestinal bacterial community. However, information on gut microbiota for wild endangered carnivores is scarce. The goal of this study was to describe the gut microbiota of two leopard subspecies, the Amur leopard (Panthera pardus orientalis) and North Chinese leopard (Panthera pardus japonensis). Fecal samples from the Amur leopard (n = 8) and North Chinese leopard (n = 13) were collected in Northeast Tiger and Leopard National Park and Shanxi Tieqiaoshan Provincial Nature Reserve in China, respectively. The gut microbiota of leopards was analyzed via high-throughput sequencing of the V3–V4 region of bacterial 16S rRNA gene using the Life Ion S5™ XL platform. A total of 1,413,825 clean reads representing 4,203 operational taxonomic units (OTUs) were detected. For Amur leopard samples, Firmicutes (78.4%) was the dominant phylum, followed by Proteobacteria (9.6%) and Actinobacteria (7.6%). And for the North Chinese leopard, Firmicutes (68.6%), Actinobacteria (11.6%) and Fusobacteria (6.4%) were the most predominant phyla. Clostridiales was the most diverse bacterial order with 37.9% for Amur leopard and 45.7% for North Chinese leopard. Based on the beta-diversity analysis, no significant difference was found in the bacterial community composition between the Amur leopard and North Chinese leopard samples. The current study provides the initial data about the composition and structure of the gut microbiota for wild Amur leopards and North Chinese leopards, and has laid the foundation for further investigations of the health, dietary preferences and physiological regulation of leopards

    Comparative genomics reveals adaptive evolution of Asian tapeworm in switching to a new intermediate host

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    Taenia saginata, Taenia solium and Taenia asiatica (beef, pork and Asian tapeworms, respectively) are parasitic flatworms of major public health and food safety importance. Among them, T. asiatica is a newly recognized species that split from T. saginata via an intermediate host switch ∼1.14 Myr ago. Here we report the 169- and 168-Mb draft genomes of T. saginata and T. asiatica. Comparative analysis reveals that high rates of gene duplications and functional diversifications might have partially driven the divergence between T. asiatica and T. saginata. We observe accelerated evolutionary rates, adaptive evolutions in homeostasis regulation, tegument maintenance and lipid uptakes, and differential/specialized gene family expansions in T. asiatica that may favour its hepatotropism in the new intermediate host. We also identify potential targets for developing diagnostic or intervention tools against human tapeworms. These data provide new insights into the evolution of Taenia parasites, particularly the recent speciation of T. asiatica

    Chinese Herbal Medicines for the Treatment of Type A H1N1 Influenza: A Systematic Review of Randomized Controlled Trials

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    Chinese herbs are thought to be effective for type A H1N1 influenza. Series of Chinese herbs have been authorized recommended by the Chinese government, and until now a number of clinical trials of Chinese herbs for H1N1 influenza have been conducted. However, there is no critically appraised evidence such as systematic reviews or metaanalyses on potential benefits and harms of medicinal herbs for H1N1 influenza to justify their clinical use and their recommendation. CENTRAL, MEDLINE, EMBASE, CBM, CNKI, VIP, China Important Conference Papers Database, China Dissertation Database, and online clinical trial registry websites were searched for published and unpublished randomized controlled trials (RCTs) of Chinese herbs for H1N1 influenza till 31 August, 2011. A total of 26 RCTs were identified and reviewed. Most of the RCTs were of high risk of bias with flawed study design and poor methodological quality. The combination of several Chinese herbal medicines with or without oseltamivir demonstrated positive effect on fever resolution, relief of symptoms, and global effectiveness rate compared to oseltamivir alone. However, only one herbal medicine showed positive effect on viral shedding. Most of the trials did not report adverse events, and the safety of herbal medicines is still uncertain. Some Chinese herbal medicines demonstrated potential positive effect for 2009 type A H1N1 influenza; however, due to the lack of placebo controlled trial and lack of repeated test of the intervention, we could not draw confirmative conclusions on the beneficial effect of Chinese herbs for H1N1 influenza. More rigorous trials are warranted to support their clinical use

    Aqueous preparation of surfactant-free copper selenide nanowires

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    Uniform surfactant-free copper selenide (Cu2- x Se) nanowires were prepared via an aqueous route. The effects of reaction parameters such as Cu/Se precursor ratio, Se/NaOH ratio, and reaction time on the formation of nanowires were comprehensively investigated. The results show that Cu2- x Se nanowires were formed through the assembling of CuSe nanoplates, accompanied by their self-redox reactions. The resultant Cu2- x Se nanowires were explored as a potential thermoelectric candidate in comparison with commercial copper selenide powder. Both synthetic and commercial samples have a similar performance and their figures of merit are 0.29 and 0.38 at 750K, respectively

    A New Approach to Identify Social Vulnerability to Climate Change in the Yangtze River Delta

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    This paper explored a new approach regarding social vulnerability to climate change, and measured social vulnerability in three parts: (1) choosing relevant indicators of social vulnerability to climate change; (2) based on the Hazard Vulnerability Similarity Index (HVSI), our method provided a procedure to choose the referenced community objectively; and (3) ranked social vulnerability, exposure, sensitivity, and adaptability according to profiles of similarity matrix and specific attributes of referenced communities. This new approach was applied to a case study of the Yangtze River Delta (YRD) region and our findings included: (1) counties with a minimum and maximum social vulnerability index (SVI) were identified, which provided valuable examples to be followed or avoided in the mitigation planning and preparedness of other counties; (2) most counties in the study area were identified in high exposure, medium sensitivity, low adaptability, and medium SVI; (3) four cities, Shanghai, Nanjing, Suzhou, and Hangzhou were much less vulnerable than others due to their high adaptability; (4) to some extent, there were geographical similarities of SVI, exposure index, sensitivity index, and adaptability index; and (5) the indicator of “Employees in primary industry” related to SVI the most, the indicator of “Renter” related to exposure index (EI) most, the indicator of “Elderly” related to sensitivity index (SI) the most, and the indicator of “Urban residents” relates to adaptability index (AI) most. These results can help decision makers find the focus of their mitigation works, where the efficient of practices will then be improved

    Multiple kernel clustering with local kernel alignment maximization

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    Kernel alignment has recently been employed for multiple kernel clustering (MKC). However, we find that most of existing works implement this alignment in a global manner, which: i) indiscriminately forces all sample pairs to be equally aligned with the same ideal similarity; and ii) is inconsistent with a well-established concept that the similarity evaluated for two farther samples in a high dimensional space is less reliable. To address these issues, this paper proposes a novel MKC algorithm with a local kernel alignment, which only requires that the similarity of a sample to its k-nearest neighbours be aligned with the ideal similarity matrix. Such an alignment helps the clustering algorithm to focus on closer sample pairs that shall stay together and avoids involving unreliable similarity evaluation for farther sample pairs. We derive a new optimization problem to implement this idea, and design a two-step algorithm to efficiently solve it. As experimentally demonstrated on six challenging multiple kernel learning benchmark data sets, our algorithm significantly outperforms the state-of-the-art comparable methods in the recent literature, verifying the effectiveness and superiority of maximizing local kernel alignment

    Mechanical Fault Diagnosis of HVCBs Based on Multi-Feature Entropy Fusion and Hybrid Classifier

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    As high-voltage circuit breakers (HVCBs) are directly related to the safety and the stability of a power grid, it is of great significance to carry out fault diagnoses of HVCBs. To accurately identify operating states of HVCBs, a novel mechanical fault diagnosis method of HVCBs based on multi-feature entropy fusion (MFEF) and a hybrid classifier is proposed. MFEF involves the decomposition of vibration signals of HVCBs into several intrinsic mode functions using variational mode decomposition (VMD) and the calculation of multi-feature entropy by the integration of three Shannon entropies. Principle component analysis (PCA) is then used to reduce the dimension of the multi-feature entropy to achieve an effective fusion of features for selecting the feature vector. The detection of an unknown fault in HVCBs is achieved using support vector data description (SVDD) trained by normal-state samples and specific fault samples. On this basis, the identification and classification of the known states are realized by the support vector machine (SVM). Three faults (i.e., closing spring force decrease fault, buffer spring invalid fault, opening spring force decrease fault) are simulated on a real SF6 HVCB to test the feasibility of the proposed method. The detection accuracies of the unknown fault are 100%, 87.5%, and 100% respectively when each of the three faults is assumed to be the unknown fault. The comparative experiments show that SVM has no ability to detect the unknown fault, and that one-class support vector machine (OCSVM) has a weaker ability to detect the unknown fault than SVDD. For known-state classification, the adoption of the MFEF method achieved an accuracy of 100%, while the use of a single-feature method only achieved an accuracy of 75%. These results indicate that the proposed method combining MFEF with hybrid classifier is thus more efficient and robust than traditional methods
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