Fluorine-plasma treated AlGaN/GaN high electronic mobility transistors under off-state overdrive stress

Influences of off-state overdrive stress on the fluorine-plasma treated AlGaN/GaN high-electronic mobility transistors(HEMTs)are experimentally investigated.It is observed that the reverse leakage current between the gate and source decreases after the off-state stress,whereas the current between the gate and drain increases.By analyzing those changes of the reverse currents based on the Frenkel–Poole model,we realize that the ionization of fluorine ions occurs during the off-state stress.Furthermore,threshold voltage degradation is also observed after the off-state stress,but the degradations of AlGaN/GaN HEMTs treated with different F-plasma RF powers are different.By comparing the differences between those devices,we find that the F-ions incorporated in the GaN buffer layer play an important role in averting degradation.Lastly,suggestions to obtain a more stable fluorine-plasma treated AlGaN/GaN HEMT are put forwarded.

Clinical Analysis of 15 Patients with Adult-Type Pulmonary Blastoma

OBJECTIVE To study the clinical and histopathological characteristics of pulmonary blastoma(PB),and to review the diagnostic criterion and treatment methods.METHODS Clinical and histopathological data from 15 cases of PB in this hospital,from 1990 to 2006,were retrospectively analyzed.RESULTS Surgical procedures were conducted in all 15 patients,including pulmonary lobectomy in 9,lobectomy of the 2 right pulmonary lobes in 2,excision of pulmonary segments in 1,lobectomy and bronchoplasty in 1,lobectomy and angioplasty in 1,and excision of the whole left lung in 1.Of the 15 cases,11 were misdiagnosed as lung cancer,2 were doubted to be a benign tumor before surgery,1 was suspected to be a malignant mesenchymoma,and only 1 was diagnosed as a PB.CONCLUSION Preoperative final diagnosis of PB is very difficult,since the clinical symptoms of the disease are nonspecific.To confirm the diagnosis,comprehensive consideration of the factors,such as the clinical manifestations,morphological characteristics and immunohistochemical tumor markers,should be taken.Surgery is the treatment of choice for PB,and a thorough removal is the key to a cure.PB has a high malignancy and o en recurs and metastasizes,usually with a poor prognosis.

Development of Slippery Liquid-Infused Porous Surface on AZ31 Mg Alloys for Corrosion Protection

The relatively poor corrosion resistance remarkably limits the wide applications of Mg alloys in practice,although they possess many attractive properties,like low density,high specific strength,and good biocompatibility.The formation of a protective coating can effectively suppress the corrosion.In this work,a slippery liquid-infused porous surface(SLIPS),with good surface hydrophobicity,stability,and self-healing property,was formed on AZ31 Mg alloys.The development of SLIPS requires suitable porous micro/nanostructures.Layered double hydroxide(LDH),with effective corrosion resistance for Mg alloys,was a good candidate to accommodate the liquid lubricant.Especially,different temperatures were applied to in situ form MgAl-LDH on AZ31 Mg alloys.The results showed that the temperature of 120℃was the best condition for the SLIPS to provide good corrosion protection for Mg alloys,with the lowest corrosion current density of 3.19×10^(-9)A cm^(−2).In addition,the SLIPS performed well in the long-term immersion test and abrasion test.The AZ31 Mg alloys with superior corrosion resistance and good mechanical and chemical stability can be extensively applied in areas of automotive,electronics,and aerospace.

Development of metal-organic framework(MOF) decorated graphene oxide/Mg Al-layered double hydroxide coating via microstructural optimization for anti-corrosion micro-arc oxidation coatings of magnesium alloy

An efcient and simple in-situ growth strategy has been discovered for the preparation of highly reproducible and continuous symbiotic ZIF-8-based anticorrosion coating by using graphene oxide(GO)/Mg AlNO3layered double hydroxides(G/LDHs) buffer layer as a new type of connecting carrier based on micro-arc oxide(MAO) coating of AZ31 magnesium alloy. The components of ZIF-8 were adsorbed and bounded to the surface of the G/LDHs buffer layer-modified substrates to promote the nucleation of ZIF-8,thus growing a phase-pure, uniform, and good symbiosis ZIF-8 membrane. ZIF-8 particles with different growth times compensate for the grain boundary defects of the G/LDHs coating precursor buffer layer to different degrees. The prepared ZIF-8-based coating has excellent stability and corrosion resistance. The results demonstrate that the G/LDHs buffer layer provides a new channel for the MOF-modified MAO substrate of AZ31 magnesium alloy. It also proves that it is feasible to build high-performance anticorrosive coatings with MOF materials.

MgAl-V_(2)O_7 ^(4-)LDHs/(PEI/MXene)_(10) composite film for magnesium alloy corrosion protection

In this study,MgAl-V_(2) O_7^(4-) LDHs/(poly(ethyleneimine)(PEI)/MXene)_n composite films were synthesized via(ⅰ) in-situ hydrothermal growth of Mg-AL layered double hydroxides(LDHs) on AZ31 alloy followed by vanadate intercalation reactions,and(ⅱ) the as-prepared MgAL-V_(2) O7^(4-) LDHs film was covered by layerby-layer assembly using(PEI/MXene)_n,where n=5,10,and 20.Film characterization revealed that the outer layers(PEI/MXene) were assembled on the surface by electrostatic interaction and provided a good coverage of LDHs nanosheets.But,microcracks appeared gradually on the surface and destroyed the film integrity with increasing number of PEI/MXene layers.The corrosion tests indicated that the MgAl-V_(2) O_7^(4-)LDHs/(PEI/MXene)_(10) composite films provided a better corrosion protection ability than that of n=5 and20.The outer layers(PEI/MXene) had a corrosion inhibition protective effect on MgAl-V_(2) O_7^(4-) LDHs film.This work opened a new perspective of the MXene materials for anticorrosion application via a layer-bylayer assembly method.