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Zhidan Zeng Qingfeng Zeng Nian Liu Artem R. Oganov Qiaoshi Zeng Yi Cui Wendy L. Mao 《Liver Transplantation》2015,5(12)
Li15Si4, the only crystalline phase that forms during lithiation of the Si anode in lithium‐ion batteries, is found to undergo a structural transition to a new phase at 7 GPa. Despite the large unit cell of Li15Si4 (152 atoms in the unit cell), ab initio evolutionary metadynamics (using the USPEX code) successfully predicts the atomic structure of this new phase (β‐Li15Si4), which has an orthorhombic structure with an Fdd2 space group. In the new β‐Li15Si4 phase Si atoms are isolated by Li atoms analogous to the original cubic phase (α‐Li15Si4), whereas the atomic packing is more efficient owing to the higher Si? Li coordination number and shorter Si? Li, Li? Li bonds. β‐Li15Si4 has substantially larger elastic moduli compared with α‐Li15Si4, and has a good electrical conductivity. As a result, β‐Li15Si4 has superior resistance to deformation and fracture under stress. The theoretical volume expansion of Si would decrease 25% if it transforms to β‐Li15Si4, instead of α‐Li15Si4, during lithiation. Moreover, β‐Li15Si4 can be recovered back to ambient pressure, providing opportunities to further investigate its properties and potential applications. 相似文献
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Didem Turgut Coşan Faruk Saydam Cansu Özbayer Fulya Doğaner Ahu Soyocak Hasan Veysi Güneş İrfan Değirmenci Hülyam Kurt Mehmet Cengiz Üstüner Cengiz Bal 《Cytotechnology》2015,67(1):97-105
Hypertension is a major health problem with increasing prevalence around the world. Tannic acid is water-soluble polyphenol that is present in tea, green tea, coffee, red wine, nuts, fruits and many plant foods. It has been reported to serve as an antioxidant or a pro-oxidant depending on the type of cells and its concentration. The purpose of our study was to evaluate the effect of tannic acid on systolic blood pressure, oxidative stress and some urinary parameters in the rat model of essential hypertension. Blood pressures of all rats were measured using the tail-cuff method. The nitric oxide synthase inhibitor N (omega)-nitro-L-arginine was administered orally at a dose of 0.5 g/l/day for 15 days to rats in order to create an animal model of hypertension. Tannic acid was intraperitoneally injected at a dose of 50 mg/kg for 15 days. Superoxide dismutase, catalase activity and the concentration of malondialdehyde (MDA) were determined in blood plasma and homogenates of heart, liver and kidney. In order to evaluate renal functions, urine pH, urine volume, urine creatine, uric acid, and urea nitrogen values were measured. Compared with the hypertension group, a decrease in MDA concentrations of heart tissue (p < 0.01), urea nitrogen values (p < 0.01) and urine volumes (p < 0.001) were established in hypertension + tannic acid group. There was also a decrease in blood pressure values (20th and 30th days) of this group, but there was no a statistical difference according to hypertension group. The findings of our research show the effect of tannic acid in lowering blood pressure in hypertensive rats. 相似文献
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Mohamed Arbi Mejri Narimen Yousfi Khemais Zouaoui Mohamed Chiheb Ben Rayana Anis Chaouachi 《Biological Rhythm Research》2015,46(5):715-724
Sleep loss is among the most common yet frequently overlooked problems. This disruptive influence is associated with an adverse lipid profile (LP) and consequently results in an increased risk of cardiovascular disease. Furthermore, it has been well established that athletes are increasingly confronted with sleep problems. The aim of this study was to explore the effect of one night of partial sleep deprivation (PSD) on the cardiovascular profile and LP in young, trained athletes. Ten male Taekwondo athletes were randomized for three sleep conditions in a counterbalanced order: (i) following a baseline sleep night (BN), (ii) following PSD at the beginning of the night (PSDBN), and (iii) following PSD at the end of the night (PSDEN). Basal cardiovascular physiological measures were recorded, and blood samples were taken in the fasted state following each sleep session (i.e., in the morning at 07:00 h). The results showed that myoglobin and creatine phosphokinase increased significantly after PSDEN but not after PSDBN. By contrast, no alteration was observed in the LP and physiological parameters following the two types of PSD. In conclusion, these results show that PSDEN increases cardiac damage biomarkers significantly, even though they do not reach clinical significance. Thus, one night of PSD does not affect the physiological responses and biomarkers of LP in Taekwondo athletes. 相似文献
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Molecular phylogenetic relationships among Asiatic shrewlike moles inferred from the complete mitogenomes 下载免费PDF全文
Robert W. Murphy Shunde Chen Xiuyue Zhang Chaochao Yan Yang Liu Zhiyu Sun Jianrong Fu Shaoying Liu Bisong Yue 《Journal of Zoological Systematics and Evolutionary Research》2015,53(2):155-160
Asiatic shrewlike moles are distributed almost entirely in south‐west China; four of the five species of the genus Uropsilus, Uropsilus aequodonenia, U. andersoni, U. investigator and U. soricipes are endemic to China. Excluding the five species, three cryptic species (U. sp. 1, U. sp. 2 and U. sp. 3) and two putative species, U. nivatus and U. atronates, are recognized. The phylogenetic relationships among the species remain unclear and these preclude investigations of their potential adaptations for living in high altitudes. We sequenced the complete mitochondrial DNA genomes of three species of Asiatic shrewlike moles (U. aequodonenia, U. andersoni and U. nivatus). Phylogenetic analyses of 16 published and our de novo mitogenomes yield single, robust trees with the relationships being (U. soricipes (U. sp. 1 (U. nivatus (U. andersoni, U. aequodonenia)))). Further, the tree verifies the validity of recently described U. aequodonenia. Analyses of selection pressure suggest that the 13 mtDNA‐encoding genes of species in the genus Uropsilus all have experienced strong purifying selection, although ATP8 accumulated a higher ratio of non‐synonymous substitutions than the other loci, which might reflect adaptation of the genus Uropsilus to different environments/elevations. 相似文献
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Ancestral origins and invasion pathways in a globally invasive bird correlate with climate and influences from bird trade 下载免费PDF全文
Hazel Jackson Diederik Strubbe Simon Tollington Robert Prys‐Jones Erik Matthysen Jim J. Groombridge 《Molecular ecology》2015,24(16):4269-4285
Invasive species present a major threat to global biodiversity. Understanding genetic patterns and evolutionary processes that reinforce successful establishment is paramount for elucidating mechanisms underlying biological invasions. Among birds, the ring‐necked parakeet (Psittacula krameri) is one of the most successful invasive species, established in over 35 countries. However, little is known about the evolutionary genetic origins of this species and what population genetic signatures tell us about patterns of invasion. We reveal the ancestral origins of populations across the invasive range and explore the potential influence of climate and propagule pressure from the pet trade on observed genetic patterns. Ring‐necked parakeet samples representing the ancestral native range (n = 96) were collected from museum specimens, and modern samples from the invasive range (n = 855) were gathered from across Europe, Mauritius and Seychelles, and sequenced for two mitochondrial DNA markers comprising 868 bp of cytochrome b and control region, and genotyped at 10 microsatellite loci. Invasive populations comprise birds that originate predominantly from Pakistan and northern areas of India. Haplotypes associated with more northerly distribution limits in the ancestral native range were more prevalent in invasive populations in Europe, and the predominance of Asian haplotypes in Europe is consistent with the higher number of Asian birds transported by the pet trade outside the native range. Successful establishment of invasive species is likely to be underpinned by a combination of environmental and anthropogenic influences. 相似文献
70.
On the effect of hydrostatic pressure on the conformational stability of globular proteins 下载免费PDF全文
Giuseppe Graziano 《Biopolymers》2015,103(12):711-718
The model developed for cold denaturation (Graziano, PCCP 2010, 12, 14245‐14252) is extended to rationalize the dependence of protein conformational stability upon hydrostatic pressure, at room temperature. A pressure− volume work is associated with the process of cavity creation for the need to enlarge the liquid volume against hydrostatic pressure. This contribution destabilizes the native state that has a molecular volume slightly larger than the denatured state due to voids existing in the protein core. Therefore, there is a hydrostatic pressure value at which the pressure−volume contribution plus the conformational entropy loss of the polypeptide chain are able to overwhelm the stabilizing gain in translational entropy of water molecules, due to the decrease in water accessible surface area upon folding, causing denaturation. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 711–718, 2015. 相似文献