Thermophysical properties study of micro/nano materials

Thermal transport in micro/nano materials is very critical, not only because the thermal property may have important influence on the performance of the materials, but also because the change of this property can reflect the inner structure change. Due to the complicated structure and small scale, the thermal properties of biomaterials, such as silkworm silk, spider silk and human head hair, are still not fully understood. Experiments are conducted on silkworm silk, spider silk and human head hair to explore their thermal properties and potential applications. This work reports on the first time study of thermal transport in the axial direction of single silkworm silks. The measured thermal diffusivity of relaxed silkworm silk and thermal conductivity are 0.39 × 10-6∼2.03 × 10-6 m2 s-1 and 0.54∼6.53 W m-1 K-1, respectively. The thermal diffusivity of silkworm silk increases up to 263% upon elongation up to 63.8%. For one of the samples studied (sample 5), its thermal conductivity goes up to 13.1 W m-1 K-1 after elongation of 68.3%, surpassing many other polymers. Three factors combine together to give rise of the remarkable thermal diffusivity increase: alignment improvement of β–sheets blocks, straightening of α– and random coils under stretching, and structural transformation from α–helices and random coils to β–sheets crystal by elongation (confirmed by our Raman spectroscopy study). Thermal path break-down is observed when elongation is beyond 63.8%. Our Raman spectroscopy study confirms this speculation: after 60% elongation, the Raman frequency started to increase, indicating the internal stress has been released due to internal structure break-down. Through series of experiments, a linear relationship between the effective thermal diffusivity and pressure-which has an effect on the effective thermal diffusivity in the form of gas conduction-is discovered and proved. By testing samples with different length, the effect of radiation and gas conduction can be eliminated. In the second part, this work reports on the much more accurate characterization of thermal transport in the axial direction of single silkworm silk, spider silk and human head hair (three parts: at the root, in the middle, and at the tip). The measured real thermal diffusivity of silkworm silk, spider silk and human head hair is 3.68 × 10-7 m2 s-1, 3.53 × 10-7 m2 s-1, 1.53 × 10-7 m2 s-1 (at the root), 1.40 × 10-7 m2 s-1 (in the middle) and 1.49 × 10-7 m2 s-1 (at the tip), respectively. The thermal conductivity and effective emissivity of the materials can also be calculated with the given value of volume-based specific heat (ρcp). After characterizing the original samples, the study of thermal transport in the axial direction of single filaments of silk (Bombyx mori) fibroin before and after heat treatment is performed. The measured thermal diffusivity of the original silk fibroin fiber ranges from 4.05 × 10-7 to 4.65 × 10-7 m2 s-1. After heat treatment (from about 140 C to about 220 C) and subtracting the gold and radiation effect, the real thermal diffusivity of silk fibroin type 1, 2 and 3, increase by 38.12%, 20.72% and 21.35%, respectively. The sample diameter change is almost negligible which is proved by checking the diameter of the sample at the same place before and after heat treatment by SEM. Raman analysis was performed on the original and heat-treated (heated at about 147 C and 179 C) samples. After the heat treatment at 147 C, the peaks at 1081, 1230 and 1665 cm-1 become slightly sharper, which is a probable sign of structural transformation from amorphous region to crystalline region. According to the literature, a model composed of amorphous regions, crystalline regions and laterally ordered regions is proposed to explain the structural changes induced by heat treatment. Due to the close packing of the more adjacent laterally ordered regions, the number and size of the crystalline regions of Bombyx mori silk fibroin increased by heat treatment. Thus the thermal properties of the samples are significantly improved

Temporal Association Rule Mining in China’s Closed-end Fund Data

Financial market plays an important role in economy. Although funds developed only a few years in China, it has been a focal point in research and practice. The conventional methods analyzing fund data are fundamental analysis and technical analysis. Data mining can extract implicit, previously unknown and potentially useful knowledge from data. This paper presents the new technique to analyze China’s closed-end fund data and temporal association rules (TAR) are discovered which reflect the relationship among open price, close price, trading volume and grail index. Experimental results show some interesting outcomes

The crossing number of locally twisted cubes

The {\it crossing number} of a graph $G$ is the minimum number of pairwise intersections of edges in a drawing of $G$. Motivated by the recent work [Faria, L., Figueiredo, C.M.H. de, Sykora, O., Vrt'o, I.: An improved upper bound on the crossing number of the hypercube. J. Graph Theory {\bf 59}, 145--161 (2008)] which solves the upper bound conjecture on the crossing number of $n$-dimensional hypercube proposed by Erd\H{o}s and Guy, we give upper and lower bounds of the crossing number of locally twisted cube, which is one of variants of hypercube.Comment: 17 pages, 12 figure

Application Research and Practice of TBL Innovative Teaching Method in the Course of Clinical Biochemical Testing Technology

The purpose of this study is to explore the practical application effect of TBL innovative teaching method in the course of clinical biochemistry test technology. The research object is all undergraduate students in the laboratory major of 2018 medical school of our university. The research method is comparative experiment method, the teaching method of LBL teaching is set as control group, while the experimental group adopts TBL teaching method. By the final teaching evaluation and the data collected in the process, the influence of TBL teaching methods on the teaching effect of the course is compared and analyzed. The evaluation methods are combined with subjective and objective evaluation. The evaluation methods include questionnaire, student mutual evaluation, final test and other multiple ways. And the results of this study showed that the average score of the experimental group using TBL teaching method was significantly higher than that of the control group using traditional teaching method. In addition, through the process evaluation, it was found that the students in the experimental group were superior to the students in the control group in terms of learning interest, communication ability and learning methods. As a result, the application of TBL teaching method in the teaching of clinical biochemistry test obviously promotes the teaching quality and effect of this course

First-line treatment for chronic myeloid leukemia: dasatinib, nilotinib, or imatinib

Imatinib, a tyrosine kinase inhibitor (TKI) of BCR-ABL, was the standard first-line therapy for chronic myeloid leukemia (CML) for almost 10 years. Dasatinib and nilotinib, two newer drugs with higher potency than imatinib against BCR-ABL and activity against most imatinib-resistant BCR-ABL mutations, have each shown superior efficacy compared with imatinib for first-line treatment of chronic-phase CML in randomized phase 3 trials. With 14 months follow-up time, available data suggest no obvious differences in efficacy between dasatinib and nilotinib. Compared with imatinib, dasatinib is associated with higher rates of pleural effusion and thrombocytopenia, but lower rates of edema, gastrointestinal AEs, musculoskeletal AEs, and rash. Nilotinib is associated with higher rates of dermatologic toxicity, headache, and biochemical abnormalities associated with hepatic and pancreatic toxicity compared with imatinib, but lower rates of edema, gastrointestinal AEs, muscle spasm, and neutropenia. Several studies have shown that poor adherence to imatinib detrimentally affects responses and should be considered in patients with a suboptimal response. The different dosing requirements of dasatinib (once daily with or without food) and nilotinib (twice daily with fasting) may be an additional factor in selecting frontline agents. This review compares and contrasts the three FDA approved first line TKI agents