Wuhan University

About: Wuhan University is a education organization based out in Wuhan, China. It is known for research contribution in the topics: Computer science & Population. The organization has 92849 authors who have published 92882 publications receiving 1691049 citations. The organization is also known as: WHU & Wuhan College.

Functional screen reveals SARS coronavirus nonstructural protein nsp14 as a novel cap N7 methyltransferase

Abstract: The N7-methylguanosine (m7G) cap is the defining structural feature of eukaryotic mRNAs. Most eukaryotic viruses that replicate in the cytoplasm, including coronaviruses, have evolved strategies to cap their RNAs. In this report, we used a yeast genetic system to functionally screen for the cap-forming enzymes encoded by severe acute respiratory syndrome (SARS) coronavirus and identified the nonstructural protein (nsp) 14 of SARS coronavirus as a (guanine-N7)-methyltransferase (N7-MTase) in vivo in yeast cells and in vitro using purified enzymes and RNA substrates. Interestingly, coronavirus nsp14 was previously characterized as a 3'-to-5' exoribonuclease, and by mutational analysis, we mapped the N7-MTase domain to the carboxy-terminal part of nsp14 that shows features conserved with cellular N7-MTase in structure-based sequence alignment. The exoribonuclease active site was dispensable but the exoribonuclease domain was required for N7-MTase activity. Such combination of the 2 functional domains in coronavirus nsp14 suggests that it may represent a novel form of RNA-processing enzymes. Mutational analysis in a replicon system showed that the N7-MTase activity was important for SARS virus replication/transcription and can thus be used as an attractive drug target to develop antivirals for control of coronaviruses including the deadly SARS virus. Furthermore, the observation that the N7-MTase of RNA life could function in lieu of that in DNA life provides interesting evolutionary insight and practical possibilities in antiviral drug screening.

Synergistic Na-storage reactions in Sn4P3 as a high-capacity, cycle-stable anode of Na-ion batteries.

Abstract: Room-temperature Na-ion batteries have attracted great interest as a low cost and environmentally benign technology for large scale electric energy storage, however their development is hindered by the lack of suitable anodic host materials. In this paper, we described a green approach for the synthesis of Sn4P3/C nanocomposite and demonstrated its excellent Na-storage performance as a novel anode of Na-ion batteries. This Sn4P3/C anode can deliver a very high reversible capacity of 850 mA h g(-1) with a remarkable rate capability with 50% capacity output at 500 mA g(-1) and can also be cycled with 86% capacity retention over 150 cycles due to a synergistic Na-storage mechanism in the Sn4P3 anode, where the Sn nanoparticles act as electronic channels to enable electrochemical activation of the P component, while the elemental P and its sodiated product Na3P serve as a host matrix to alleviate the aggregation of the Sn particles during Na insertion reaction. This mechanism may offer a new approach to create high capacity and cycle-stable alloy anodes for Na-ion batteries and other electrochemical energy storage applications.

Surface Plasmon‐Enhanced Photodetection in Few Layer MoS2 Phototransistors with Au Nanostructure Arrays

Abstract: 2D Molybdenum disulfide (MoS2 ) is a promising candidate material for high-speed and flexible optoelectronic devices, but only with low photoresponsivity. Here, a large enhancement of photocurrent response is obtained by coupling few-layer MoS2 with Au plasmonic nanostructure arrays. Au nanoparticles or nanoplates placed onto few-layer MoS2 surface can enhance the local optical field in the MoS2 layer, due to the localized surface plasmon (LSP) resonance. After depositing 4 nm thick Au nanoparticles sparsely onto few-layer MoS2 phototransistors, a doubled increase in the photocurrent response is observed. The photocurrent of few-layer MoS2 phototransistors exhibits a threefold enhancement with periodic Au nanoarrays. The simulated optical field distribution confirms that light can be trapped and enhanced near the Au nanoplates. These findings offer an avenue for practical applications of high performance MoS2 -based optoelectronic devices or systems in the future.

Cellulose–Silica Nanocomposite Aerogels by In Situ Formation of Silica in Cellulose Gel

Abstract: Aerogels with their low density (0.004–0.500 gcm ), large internal surface area, and large open pores are promising candidates for various advanced applications. The utilization of inorganic aerogels, however, has been hampered by their poor mechanical properties. A prominent example is silica aerogel, which is prepared by an organic sol–gel process, and has unique features, such as ultralow density (the lightest silica aerogel has a density that is similar to the density of air, which is 0.00129 gcm ), near transparency, and low thermal conductivity. However, the extreme fragility of this aerogel necessitates its reinforcement for practical uses. A typical method is hybridization with organic polymers, such as polyurea, polyurethane, poly(methyl methacrylate), polyacrylonitrile, and polystyrene. Other candidates for the reinforcement of inorganic aerogels are insoluble polysaccharides, which are abundantly available and show wide varieties in structure and properties. The useful features of these compounds are hydrophilicity, biocompatibility, hydroxy reactivity, and reasonable thermal and mechanical stabilities. For example, nanofibrillar bacterial cellulose and microfibrillated cellulose gel have been proposed as templates for cobalt ferrite nanoparticles and titanium dioxide. While in the above-mentioned work native cellulose with cellulose I crystallinity was used, cellulose can be prepared as a hydrogel with cellulose II crystallinity through dissolution and coagulation. Some of the resulting aerogels have remarkable mechanical strength and light transmittance. They have high porosity with open structures and thus provide an effective substrate for the synthesis of metallic nanoparticles. To further utilize the regenerated cellulose gel, we herein attempted in situ synthesis of silica in cellulose gels. While a similar attempt has been reported, in which the cellulose gel was obtained from solution in N-methylmorpholine-N-oxide monohydrate, the development of the nanostructure (nitrogen BET surface area of 220–290 mg ) and the level of silica loading (less than 13% w/w) were rather limited. By using the aqueous alkali-based solvent, we obtained the cellulose aerogel with a surface area of 356 mg , and a silica loading of more than 60% w/w resulted in surface areas that exceeded 600 mg . We used the sol–gel synthesis method toward nanostructured silica, which typically starts from tetraethyl orthosilicate (TEOS). The resulting composite gels were dried with supercritical CO2 to give cellulose–silica aerogels with low density, moderate light transmittance, a large surface area, high mechanical integrity, and excellent heat insulation. This method can also lead to fabrication of silica-only aerogels through the removal of cellulose by calcination, that is, the use of cellulose aerogel as sacrificial template. Figure 1 shows the preparation of the aerogel. The cellulose hydrogel is a transparent material that has a water content of 92% and a porosity of 95%. The sol–gel process catalyzed by ammonia converts TEOS to SiO2, which is deposited on the cellulose network (Figure 1b). The composite is converted to an aerogel by drying with supercritical CO2 to maintain the porous structure (Figure 1c), thus resulting in a flexible and translucent cellulose–silica aerogel. Subsequent calcination removes the cellulose matrix to give a silica-only aerogel (Figure 1d and g). The cellulose aerogel is composed of regenerated cellulose fibrils, which are typically less than 10 nm wide (Figure 2a). The BET surface area of 356 mg 1 (determined by