Research on Coupling Transfer Characteristics of Vibration Energy of Free Piston Linear Generator

In order to clarify the mechanism and main influencing factors of the vibration energy coupling transmission with a dual-piston structure,a thermodynamic and dynamic coupling model of the free piston linear generator(FPLG)was established.The system energy conversion,vibration energy coupling transmission,and influencing factors were studied in detail.The coupling transmission paths and the secondary influence mechanism from in-cylinder combustion on vibration energy transmission were obtained.In addition,the influence of the movement characteristics of the dual-piston on the vibration energy transmission was studied,and the typical parameter variation law was obtained,which provides theoretical guidance for the subsequent vibration reduction design of the FPLG.

Self-supported NiFe-LDH nanosheets on NiMo-based nanorods as high-performance bifunctional electrocatalysts for overall water splitting at industrial-level current densities

Efficient,durable and economic electrocatalysts are crucial for commercializing water electrolysis technology.Herein,we report an advanced bifunctional electrocatalyst for alkaline water splitting by growing NiFe-layered double hydroxide(NiFe-LDH)nanosheet arrays on the conductive NiMo-based nanorods deposited on Ni foam to form a three-dimensional(3D)architecture,which exhibits exceptional performances for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In overall water splitting,only the low operation voltages of 1.45/1.61 V are required to reach the current density of 10/500 mA·cm^(-2),and the continuous water splitting at an industrial-level current density of 500 mA·cm^(-2) shows a negligible degradation(1.8%)of the cell voltage over 1000 h.The outstanding performance is ascribed to the synergism of the HER-active NiMo-based nanorods and the OER-active NiFe-LDH nanosheet arrays of the hybridized 3D architecture.Specifically,the dense NiFe-LDH nanosheet arrays enhance the local pH on cathode by retarding OH-diffusion and enlarge the electrochemically active surface area on anode,while the conductive NiMo-based nanorods on Ni foam much decrease the charge-transfer resistances of both electrodes.This study provides an efficient strategy to explore advanced bifunctional electrocatalysts for overall water splitting by rationally hybridizing HER-and OER-active components.

House dust mite allergens and nitrated products: Identification and risk assessment in indoor dust

Air pollutants can potentially lead to nitration of allergic proteins,thus promoting sensitization of these allergens.However,little is currently known about the nitration status of house dust mite(HDM)allergens.We identified the occurrence of nitrated products of two major HDM allergens Der f 1 and Der p 1 in dust samples collected from college dormitories in eastern China and assessed their associated health risk.The results showed that both non-nitrated and nitrated forms of the two allergens were detected in the dust in the range of non-detected(ND)-10.6,1.44-15.4,ND-22.4,ND-7.28μg/g for non-nitrated Der f 1,nitrated Der f 1,non-nitrated Der p 1 and nitrated Der p 1,respectively.The median rates of nitration were determined as 74.0%for Der f 1 and 20.4% for Der p 1 at consideration of one nitration site.Further analysis reveals that the levels of HDM allergens and their nitrated products were found to be generally higher during winter,in dormitories of lower altitude and with female occupants.Furthermore,the calculated risk indexes were at considerably high levels.Our findings suggest that nitrated HDM allergens have already accumulated in the environment at such significant levels and their associated health risk calls for our immediate attention.

Hundredfold increase of stimulated Brillouin-scattering bandwidth in whispering-gallery mode resonators

Backward stimulated Brillouin scattering(SBS)is widely exploited for various applications in optics and optoelectronics.It typically features a narrow gain bandwidth of a few tens of megahertz in fluoride crystals.Here we report a hundredfold increase of SBS bandwidth in whispering-gallery mode resonators.The crystalline orientation results in a large variation of the acoustic phase velocity upon propagation along the periphery,from which a broad Brillouin gain is formed.Over 2.5 GHz wide Brillouin gain profile is theoretically found and experimentally validated.SBS phenomena with Brillouin shift frequencies ranging from 11.73 to 14.47 GHz in ultrahigh Q Z-cut magnesium fluoride cavities pumped at the telecommunication wavelength are demonstrated.Furthermore,the Brillouin-Kerr comb in this device is demonstrated.Over 400 comb lines spanning across a spectral window of 120 nm are observed.Our finding paves a new way for tailoring and harnessing the Brillouin gain in crystals.

Unravelling the critical role of surface Nafion adsorption in Ptcatalyzed oxygen reduction reaction by in situ electrical transport spectroscopy

Solid-state ionic conductor is a vital part in all electrochemical energy conversion devices. As a widely-applied protonconducting polymer and stabilizer for electrode preparation, Nafion has key applications in electrochemical devices operated under acidic conditions. Specific adsorption of Nafion on the catalyst surface is considered to result in partial loss of intrinsic activity in reactions such as oxygen reduction reaction(ORR), due to its comprehensive occupation of active sites. Many in situ characterization methods such as voltammetric fingerprinting and spectroscopic approaches have been used to explore the dynamic adsorption of Nafion on the electrode surface. However, most of current efforts have been focused on the behaviors of Nafion itself, with little attention paid to its effects on the adsorption of surface intermediates. Here, we employed the in situ electrical transport spectroscopy(ETS) to investigate Nafion adsorption on Pt catalysts and its effects on the ORR intermediates.Our findings suggest that specific adsorption of Nafion results in the increased coverage of oxygen intermediates with weaker adsorption strength, which in turn plays a critical role in the reaction selectivity. The successful application of ETS on the dynamic characterization of reaction intermediates provides a novel perspective for catalyst design in ORR-related applications in future sustainable chemistry.