Zhejiang University

About: Zhejiang University is a education organization based out in Hangzhou, Zhejiang, China. It is known for research contribution in the topics: Catalysis & Population. The organization has 161257 authors who have published 183264 publications receiving 3417592 citations. The organization is also known as: Chekiang University & Zheda.

Free transverse vibrations of double-walled carbon nanotubes using a theory of nonlocal elasticity

Abstract: Based on theory of nonlocal elasticity, a nonlocal double-elastic beam model is developed for the free transverse vibrations of double-walled carbon nanotubes. The effect of small length scale is incorporated in the formulation. With this nonlocal double-elastic beam model, explicit expressions are derived for natural frequencies and associated amplitude ratios of the inner to the outer tubes for the case of simply supported double-walled carbon nanotubes. The effect of small length scale on the properties of vibrations is discussed. It is demonstrated that the natural frequencies and the associated amplitude ratios of the inner to the outer tubes are dependent upon the small length scale. The effect of small length scale is related to the vibrational mode and the aspect ratio.

All-temperature batteries enabled by fluorinated electrolytes with non-polar solvents

Abstract: Carbonate electrolytes are commonly used in commercial non-aqueous Li-ion batteries. However, the high affinity between the solvents and the ions and high flammability of the carbonate electrolytes limits the battery operation temperature window to −20 to + 50 °C and the voltage window to 0.0 to 4.3 V. Here, we tame the affinity between solvents and Li ions by dissolving fluorinated electrolytes into highly fluorinated non-polar solvents. In addition to their non-flammable characteristic, our electrolytes enable high electrochemical stability in a wide voltage window of 0.0 to 5.6 V, and high ionic conductivities in a wide temperature range from −125 to + 70 °C. We show that between −95 and + 70 °C, the electrolytes enable LiNi0.8Co0.15Al0.05O2 cathodes to achieve high Coulombic efficiencies of >99.9%, and the aggressive Li anodes and the high-voltage (5.4 V) LiCoMnO4 to achieve Coulombic efficiencies of >99.4% and 99%, respectively. Even at −85 °C, the LiNi0.8Co0.15Al0.05O2 || Li battery can still deliver ~50% of its room-temperature capacity. Batteries generally do not perform well at extreme temperatures, and electrolytes are mainly to blame. Here, the authors dissolve fluorinated electrolytes in highly fluorinated non-polar solvents, enabling batteries that can operate at a wide temperature range (−125 to +70 °C).

Microbial biomass and community structure in a sequence of soils with increasing fertility and changing land use

Abstract: The microbial biomass and community structure of eight Chinese red soils with different fertility and land use history was investigated. Two community based microbiological measurements, namely, community level physiological profiling (CLPP) using Biolog sole C source utilization tests and phospholipid fatty acid (PLFA) profiles, were used to investigate the microbial ecology of these soils and to determine how land use alters microbial community structure. Microbial biomass-C and total PLFAs were closely correlated to organic carbon and total nitrogen, indicating that these soil microbial measures are potentially good indices of soil fertility in these highly weathered soils. Metabolic quotients and C source utilization were not correlated with organic carbon or microbial biomass. Multivariate analysis of sole carbon source utilization patterns and PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. PLFAs showed these differences more than CLPP methods. Consequently, PLFA analysis was a better method for assessing broad-spectrum community differences and at the same time attempting to correlate changes with soil fertility. Soils from tea orchards were particularly distinctive in their CLPP. A modified CLPP method, using absorbance readings at 405 nm and different culture media at pH values of 4.7 and 7.0, showed that the discrimination obtained can be influenced by the culture conditions. This method was used to show that the distinctive microbial community structure in tea orchard soils was not, however, due to differences in pH alone.

An instant multi-responsive porous polymer actuator driven by solvent molecule sorption

Abstract: Fast actuation speed, large-shape deformation and robust responsiveness are critical to synthetic soft actuators. A simultaneous optimization of all these aspects without trade-offs remains unresolved. Here we describe porous polymer actuators that bend in response to acetone vapour (24 kPa, 20 °C) at a speed of an order of magnitude faster than the state-of-the-art, coupled with a large-scale locomotion. They are meanwhile multi-responsive towards a variety of organic vapours in both the dry and wet states, thus distinctive from the traditional gel actuation systems that become inactive when dried. The actuator is easy-to-make and survives even after hydrothermal processing (200 °C, 24 h) and pressing-pressure (100 MPa) treatments. In addition, the beneficial responsiveness is transferable, being able to turn 'inert' objects into actuators through surface coating. This advanced actuator arises from the unique combination of porous morphology, gradient structure and the interaction between solvent molecules and actuator materials.

A strongly adhesive hemostatic hydrogel for the repair of arterial and heart bleeds

Abstract: Uncontrollable bleeding is a major problem in surgical procedures and after major trauma. Existing hemostatic agents poorly control hemorrhaging from traumatic arterial and cardiac wounds because of their weak adhesion to wet and mobile tissues. Here we design a photo-reactive adhesive that mimics the extracellular matrix (ECM) composition. This biomacromolecule-based matrix hydrogel can undergo rapid gelling and fixation to adhere and seal bleeding arteries and cardiac walls after UV light irradiation. These repairs can withstand up to 290 mm Hg blood pressure, significantly higher than blood pressures in most clinical settings (systolic BP 60–160 mm Hg). Most importantly, the hydrogel can stop high-pressure bleeding from pig carotid arteries with 4~ 5 mm-long incision wounds and from pig hearts with 6 mm diameter cardiac penetration holes. Treated pigs survived after hemostatic treatments with this hydrogel, which is well-tolerated and appears to offer significant clinical advantage as a traumatic wound sealant. Uncontrollable bleeding is a major problem in surgery and after trauma. Here the authors design a photo-reactive adhesive that mimics the composition of connective tissue and is able to stop high pressure bleeding within half a minute.