| 691. |
- Liu, Ting, et al.
(författare)
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Solid-to-fluid-like DNA transition in viruses facilitates infection.
- 2014
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 111:41, s. 14675-14680
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Tidskriftsartikel (refereegranskat)abstract
- Releasing the packaged viral DNA into the host cell is an essential process to initiate viral infection. In many double-stranded DNA bacterial viruses and herpesviruses, the tightly packaged genome is hexagonally ordered and stressed in the protein shell, called the capsid. DNA condensed in this state inside viral capsids has been shown to be trapped in a glassy state, with restricted molecular motion in vitro. This limited intracapsid DNA mobility is caused by the sliding friction between closely packaged DNA strands, as a result of the repulsive interactions between the negative charges on the DNA helices. It had been unclear how this rigid crystalline structure of the viral genome rapidly ejects from the capsid, reaching rates of 60,000 bp/s. Through a combination of single-molecule and bulk techniques, we determined how the structure and energy of the encapsidated DNA in phage λ regulates the mobility required for its ejection. Our data show that packaged λ-DNA undergoes a solid-to-fluid-like disordering transition as a function of temperature, resulting locally in less densely packed DNA, reducing DNA-DNA repulsions. This process leads to a significant increase in genome mobility or fluidity, which facilitates genome release at temperatures close to that of viral infection (37 °C), suggesting a remarkable physical adaptation of bacterial viruses to the environment of Escherichia coli cells in a human host.
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| 692. |
- Liu, Wei, et al.
(författare)
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Slag Blended Cement Paste Carbonation under Different CO(2)Concentrations: Controls on Mineralogy and Morphology of Products
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:15, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the effect of different CO(2)concentrations on the carbonation results of slag blended cement pastes, carbonation experiments under natural (0.03% CO2) and accelerated conditions (3, 20, and 100% CO2) were investigated with various microscopic testing methods, including X-ray diffraction (XRD),Si-29 magic angle spinning nuclear magnetic resonance (Si-29 MAS NMR) and scanning electron microscopy (SEM). The XRD results indicated that the major polymorphs of CaCO(3)after carbonation were calcite and vaterite. The values of the calcite/(aragonite + vaterite) (c/(a + v)) ratios were almost the same in all carbonation conditions. Additionally, NMR results showed that the decalcification degree of C-S-H gel exposed to 0.03% CO(2)was less than that exposed to accelerated carbonation; under accelerated conditions, it increased from 83.1 to 84.2% when the CO(2)concentration improved from 3% to 100%. In SEM observations, the microstructures after accelerated carbonation were denser than those under natural carbonation but showed minor differences between different CO(2)concentrations. In conclusion, for cement pastes blended with 20% slag, a higher CO(2)concentration (above 3%) led to products different from those produced under natural carbonation. A further increase in CO(2)concentration showed limited variation in generated carbonation products.
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| 693. |
- Liu, Wei, et al.
(författare)
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XRD and( 29)Si MAS NMR study on carbonated cement paste under accelerated carbonation using different concentration of CO2
- 2019
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Ingår i: Materials Today Communications. - : Elsevier BV. - 2352-4928. ; 19:June, s. 464-470
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the chemical composition of cement pastes, exposed to accelerated carbonation using different concentration of CO2 (3%, 10%, 20%, 50%,100%), have been determined and compared with those of natural carbonation (0.03%). Quantitative X-ray diffraction (QXRD) and( 29)Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) were used for characterisation and quantitative analysis of the carbonated phases. The obtained QXRD results revealed that the complete carbonation was hardly attained. Calcite, aragonite and vaterite were in co-existence after accelerated carbonation, while vaterite was dominant. The preferential polymorphic precipitation of the three crystal forms of calcium carbonate was affected by the carbonation degree of C-S-H and the duration of the carbonation process, but not by the concentration of CO2. The NMR results indicated that C-S-H gel was strongly decalcified, and calcium modified silica gel was formed after carbonation. The C-S-H decalcification, under all the accelerated carbonation conditions, was clearly more pronounced than that under the natural carbonation conditions. When the concentration of CO2 was in the range of 3%-20%, the ratio of decalcified to remaining C-S-H was similar, in a range of 5-6, while under the higher concentration of CO2 this ratio was increased to > 8. Therefore, in consideration of both acceleration rate and measurement uncertainty, the higher concentration, up to 20%, of CO2 in an accelerated carbonation should be applicable.
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| 694. |
- Liu, Xuan, et al.
(författare)
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Increased southerly and easterly water vapor transport contributed to the dry-to-wet transition of summer precipitation over the Three-River Headwaters in the Tibetan Plateau
- 2023
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Ingår i: Advances in Climate Change Research. - 1674-9278 .- 2524-1761. ; 14:4, s. 502-510
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Tidskriftsartikel (refereegranskat)abstract
- The Three-River Headwaters (TRH) region in the Tibetan Plateau is vulnerable to climate change; changes in summer (June–August) precipitation have a significant impact on water security and sustainability in both local and downstream areas. However, the changes in summer precipitation of different intensities over the TRH region, along with their influencing factors, remain unclear. In this study, we used observational and ERA5 reanalysis data and employed a precipitation categorization and water vapor budget analysis to quantify the categorized precipitation variations and investigate their possible linkages with the water vapor budget. Our results showed an increasing trend in summer precipitation at a rate of 0.9 mm per year (p < 0.1) during 1979–2020, with a significant dry-to-wet transition in 2002. The category ‘very heavy precipitation’ (≥10 mm d−1) contributed 65.1% of the increased summer precipitation, which occurred frequently in the northern TRH region. The dry-to-wet transition was caused by the effects of varied atmospheric circulations in each subregion. Southwesterly water vapor transport through the southern boundary was responsible for the increased net water vapor flux in the western TRH region (158.2%), while southeasterly water vapor transport through the eastern boundary was responsible for the increased net water vapor flux in the central TRH (155.2%) and eastern TRH (229.2%) regions. Therefore, we inferred that the dry-to-wet transition of summer precipitation and the increased ‘very heavy precipitation’ over the TRH was caused by increased easterly and southerly water vapor transport.
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| 695. |
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| 696. |
- Liu, Yong, et al.
(författare)
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Deletion Of XIAP reduces the severity of acute pancreatitis via regulation of cell death and nuclear factor-kappa B activity
- 2017
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Ingår i: Cell Death and Disease. - : NATURE PUBLISHING GROUP. - 2041-4889. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Severe acute pancreatitis (SAP) still remains a clinical challenge, not only for its high mortality but the uncontrolled inflammatory progression from acute pancreatitis (AP) to SAP. Cell death, including apoptosis and necrosis are critical pathology of AP, since the severity of pancreatitis correlates directly with necrosis and inversely with apoptosis Therefore, regulation of cell death from necrosis to apoptosis may have practicably therapeutic value. X-linked inhibitor of apoptosis protein (XIAP) is the best characterized member of the inhibitor of apoptosis proteins (IAP) family, but its function in AP remains unclear. In the present study, we investigated the potential role of XIAP in regulation of cell death and inflammation during acute pancreatitis. The in vivo pancreatitis model was induced by the administration of cerulein with or without lipopolysaccharide (LPS) or by the administration of L-arginine in wild-type or XIAP-deficient mice, and ex vivo model was induced by the administration of cerulein+LPS in AR42J cell line following XIAP inhibition. The severity of acute pancreatitis was determined by serum amylase activity and histological grading. XIAP deletion on cell apoptosis, necrosis and inflammatory response were examined. Caspases activities, nuclear factor kappa B (NF-kappa B) activation and receptor-interacting protein kinase1 (RIP1) degradation were assessed by western blot. Deletion of XIAP resulted in the reduction of amylase activity, decrease of NF-kappa B activation and less release of TNF-alpha and IL-6, together with increased caspases activities and RIP1 degradation, leading to enhanced apoptosis and reduced necrosis in pancreatic acinar cells and ameliorated the severity of acute pancreatitis. Our results indicate that deletion of XIAP switches cell death away from necrosis to apoptosis and decreases the inflammatory response, effectively attenuating the severity of AP/SAP. The critical role of XIAP in cell death and inflammation suggests that inhibition of XIAP represents a potential therapeutic strategy for the treatment of acute pancreatitis.
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| 697. |
- Liu, Y., et al.
(författare)
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Increases in China's wind energy production from the recovery of wind speed since 2012
- 2022
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 17:11
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Tidskriftsartikel (refereegranskat)abstract
- China has realized a 56-fold increase in installed wind capacity, from 5.9 GW in 2007 to 328 GW in 2021. In addition to increasing installed capacity, plans to substantially increase wind energy production for climate change mitigation also depend on future wind speeds, which strongly influences the efficiencies of installed turbines within individual wind farms. A reversal in globally decreasing wind speeds over several decades has been reported previously. However, subsequent studies using other data sources reported only a slight increase or no reversal in China. These uncertainties regarding China's wind energy production hamper estimates of wind energy production potential. Here, our analysis of quality-controlled wind speed measurements from in-situ stations shows that the wind speed decline in China reversed significantly since 2012 (P < 0.001), but with substantial spatio-temporal variability. We further estimated the capacity factor (CF) growth and the wind power gain solely associated with the changes in wind speed ranges from 31.6 to 56.5 TWh yr(-1) based on the 2019 installed capacity. This estimate explains 22.0%-39.3% of the rapid increase in wind generation CF in China during 2012-2019. The result implies that the site selection of wind farms should consider both current wind situation and future wind speed trends. Further studies are needed to understand the driving factor of wind speed recovery in support of the wind energy industry.
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| 698. |
- Liu, Zhengtao, et al.
(författare)
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Clear mortality gap caused by graft macrosteatosis in Chinese patients after cadaveric liver transplantation
- 2020
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Ingår i: Hepatobiliary surgery and nutrition. - : AME Publishing Company. - 2304-3881 .- 2304-389X. ; 9:6, s. 739-758
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Tidskriftsartikel (refereegranskat)abstract
- Background: Liver transplantation (LT) is one of the most effective surgical treatment for patients with end-stage liver disease. Steatosis is a contributor for inferior graft quality. But its impact and safety on transplantation was less assessed in Chinese patients. Methods: Graft steatosis and related information involved in recipients, donors and surgical procedures were retrospectively collected from 239 patients. Results: Donor macrosteatosis (MaS) caused about 2.14 and 2.80 folds of increment on patient and graft mortality. Dose-response analysis revealed prominent risk of grafts on overall patient/organ mortality when MaS content exceeded 10% (P<0.05). Noteworthy, deaths were only observed in MaS group when concurrent with extremely higher post-transplant alanine aminotransferase (ALT, 64%). However, microsteatosis (MiS) grafts didn't affect outcomes after LT. In a cohort of Chinese patients, MaS had comprehensive effects on post-transplant outcomes with relatively lower safety threshold at 10%. Mortality gap caused by MaS grafts was observed in patients with severer ischemia reperfusion injury. Conclusions: Our study revealled the graft MaS affected the post-transplant outcomes in lower risk cutoff in Chinese patients. Further study is worthy to validate these results and investigate inner mechanism under the phenomenon.
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| 699. |
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| 700. |
- Lu, C. L., et al.
(författare)
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Charge-order breaking and ferromagnetism in La0.4Ca0.6MnO3 nanoparticles
- 2007
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 91:3, s. 032502-
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Tidskriftsartikel (refereegranskat)abstract
- La0.4Ca0.6MnO3 nanoparticles of grain size as small as similar to 20 nm are prepared and their magnetic behaviors are investigated in order to understand the size effect of the charge ordering in manganites. The highly stable charge-ordered state can be significantly suppressed upon reduction of the grain size down to nanometer scale, while the ferromagnetism is enhanced. The magnetic phase separation due to the competition between ferromagnetic state and charge-ordered state as well as the surface spin disordering is responsible for the spin-glass-like state at low temperature. (C) 2007 American Institute of Physics.
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