Analysis of the growth of GaN epitaxy on silicon

Due to the great potential of Ga N based devices, the analysis of the growth of crack-free Ga N with high quality has always been a research hotspot. In this paper, two methods for improving the property of the Ga N epitaxial layer on Si（111） substrate are researched. Sample A, as a reference, only has an Al N buffer between the Si substrate and the epitaxy. In the following two samples, a Ga N transition layer（sample B） and an Al Ga N buffer（sample C） are grown on the Al N buffer separately. Both methods improve the quality of Ga N. Meanwhile, using the second method, the residual tensile thermal stress decreases. To further study the impact of the two introduced layers, we investigate the stress condition of Ga N epitaxial layer by Raman spectrum. According to the Raman spectrum, the calculated residual stress in the Ga N epitaxial layer is approximately 0.72 GPa for sample B and0.42 GPa for sample C. The photoluminescence property of Ga N epitaxy is also investigated by room temperature PL spectrum.

In vitro genotoxicity evaluation and metabolic study of residual glutaraldehyde in animal-derived biomaterials

Glutaraldehyde(GA)is an important additive that is mainly used in animal-derived biomaterials to improve their mechanical and antimicrobial capacities.However,GA chemical toxicity and the metabolic mechanism remain relatively unknown.Therefore,residual GA has always been a major health risk consideration for animal-derived medical devices.In this study,extracts of three biopatches were tested via the GA determination test and mouse lymphoma assay(MLA).The results showed that dissolved GA was a potential mutagen,which could induce significant cytotoxic and mutagenic effects in mouse lymphoma cells.These toxic reactions were relieved by the S9 metabolic activation(MA)system.Furthermore,we confirmed that GA concentration decreased and glutaric acid was generated during the catalytic process.We revealed GA could be oxidized via cytochrome P450 which was the main metabolic factor of S9.We found that even though GA was possibly responsible for positive reactions of animal-derived biomaterials’biocompatibility evaluation,it may not represent the real situation occurring in human bodies,owing to the presence of various detoxification mechanisms including the S9 system.Overall,in order to achieve a general balance between risk management and practical application,rational decisions based on comprehensive analyses must be considered.