We have prepared three kinds of Co-Sn intermetallic compounds, i.e., Co 3 Sn 2 , CoSn, and CoSn 2 , by mechanical alloying followed by heat-treatment. The results of ex situ X-ray diffraction analysis and charge/discharge tests indicate that the electrochemical reaction of lithium with crystalline intermetallic CoSn 2 results in the formation of Li-rich tin phase ͑Li 4.4 Sn͒, whereas the crystalline Co 3 Sn 2 and CoSn alloys only partly form Li x Sn. All three alloys in the low-crystalline obtained by further mechanical milling show improved capacity. Co 3 Sn 2 shows the best cycling performance among the three alloys, but delivers small capacity. The cycling ability of CoSn 2 was also improved by partly introducing Co and C into the alloy.Lithium-ion batteries based on a carbon/graphite anode and a transition metal-oxide cathode have been commercially used in popular portable devices such as cell phones and laptop computers for ϳ15 years. One of the most interesting and challenging goals is to develop increased capacity electrode materials in order to increase the battery energy density. The conventional anode material, graphite, has a theoretical maximum capacity of 372 mAh/g, or a volumetric capacity of 818 Ah/L ͑the density of graphite is 2.2 g/cm 3 ͒. Metals and alloys present an attractive alternative to graphite as anode materials for lithium-ion batteries due in particular to the high capacity, an acceptable rate capability, and operating potentials well above the potential of metallic lithium. For example, Sn yields a maximum theoretical capacity of 990 mAh/g or 7200 Ah/L. One major problem preventing them from the commercial application is that they undergo large volume changes during cycling, which result in disintegration of the electrodes and subsequent rapid capacity fading.This problem has been solved by the tin oxide glass materials invented by the Fuji company. 1 The new Fuji anode was claimed to have both volumetric and gravimetric capacity advantages over graphite of four and two times, respectively. It was reported that the key reasons for the success of the Fuji materials are finely dispersed tin regions which are responsible for the reversible reaction with Li, and the Li 2 O and other oxides playing the role of a "matrix-glue" to hold the particles together. 2 However, the Sn oxide-based anode has a large irreversible capacity resulting from the Li, which reacts with the oxygen bonded to Sn to form Li 2 O. An interesting approach to overcoming these problems is the use of the intermetallic compound, MЈM, which consisting of an "inactive phase MЈ," which does not react with lithium, and "active phase M," which reacts with lithium, these intermetallic compounds include Cu 6 Sn 5 alloy, [3][4][5] Ni-Sn alloys, 6,7 Sn-Fe͑-C͒ system, 8 and Sn-Mn-C system. 9 For these alloys, lithium intercalation into alloy yields a lithium alloy ͑Li x MЈSn͒ or the mixed phase of lithium-tin alloys ͑Li 4.4 Sn͒ and nano-sized metal ͑MЈ͒ by controlling the discharge depth. The role of "inactive phase MЈ" is mainly...

No abstract

No abstract

MicroRNAs (miRNAs) are a set of short (21–24 nt) noncoding RNAs that play significant regulatory roles in cells. In the past few years, research on miRNA-related problems has become a hot field of bioinformatics because of miRNAs' essential biological function. miRNA-related bioinformatics analysis is beneficial in several aspects, including the functions of miRNAs and other genes, the regulatory network between miRNAs and their target mRNAs, and even biological evolution. Distinguishing miRNA precursors from other hairpin-like sequences is important and is an essential procedure in detecting novel microRNAs. In this study, we employed backpropagation (BP) neural network together with 98-dimensional novel features for microRNA precursor identification. Results show that the precision and recall of our method are 95.53% and 96.67%, respectively. Results further demonstrate that the total prediction accuracy of our method is nearly 13.17% greater than the state-of-the-art microRNA precursor prediction software tools.

No abstract

Background: Primiparous mothers who lack of experience and knowledge of child caring, are usually overwhelmed by multifarious stressors and challenges. Although professional support is needed for primiparas, there is a gap between the necessary high-quality services and the currently provided poor services. This study aimed to explore Chinese primiparous mothers' views on professional services, identify barriers to utilizing professional support, and further understand mothers' expectations of and preferences for the delivery of professional services. Method: A descriptive phenomenological study design was utilized in this study, and semi-structured interviews were conducted with 28 primiparous mothers who had given birth in the first year period before the interview and were selected from two community health centres in Xi'an city, Shaanxi Province, Northwest China. Each conversational interview lasted between 20 and 86 min. Colaizzi's seven-step phenomenological approach was used to analyse the data. Results: Three major themes were identified: (a) dissatisfaction with current professional services for postpartum mothers, (b) likelihood of health care professional help-seeking behaviour, (c) highlighting the demands for new health care services. The related seven sub-themes included being disappointed with current hospital services; distrusting services provided by community health centres, private institutes and commercial online platforms; preferring not seeking help from professionals as their first choice; hesitating to express their inner discourse to professionals; following confinement requirement and family burden prevents mothers from seeking professional help; experiencing urgent needs for new baby-care-related services; and determining the importance of mothers' needs. The necessity of professional support in the first month after childbirth was strongly emphasized by the participants. Online professional guidance and support were perceived as the best way to receive services in this study.

The recent discovery of the new components of the renin-angiotensin system (RAS) suggests the importance of the maintenance of cardiovascular structure and functions. To assess the role of the angiotensin-converting enzyme 2 (ACE2)-Mas receptor axis in the regulation of cardiac structure and function, the present work investigated the expression of ACE2 and Mas receptor in the heart in the cardiac remodeling that occurs in aortic constricted rats. Partial abdominal aortic ligation was carried out in Sprague-Dawley rats. Angiotensin AT1 receptor blockade and ACE inhibition were achieved by losartan and enalapril treatment, respectively. Results showed that aortic constriction increased left ventricular hypertrophy, fibrosis, mean arterial pressure (MAP), plasma renin activity (PRA) and cardiac ACE levels, but decreased the expression of cardiac ACE2 and Mas receptor. Losartan treatment significantly decreased MAP, left ventricle hypertrophy (LVH), fibrosis, and increased cardiac ACE2 and Mas expression. Enalapril also improved the cardiac parameters with a rise in cardiac ACE2, but did not change the Mas level. In conclusion, aortic constriction results in cardiac hypertrophy, fibrosis and a rise of cardiac ACE expression. Both AT1 receptor blocker and ACE inhibitor play a cardioprotective role in aortic constriction. However, AT1 receptor blocker particularly promotes cardiac ACE2 and Mas receptor levels. ACE inhibitor is associated with the inhibition of ACE and normalization of cardiac ACE2 activity.

No abstract