Identification of subsurface damage of 4H-SiC wafers by combining photo-chemical etching and molten-alkali etching

In this work,we propose to reveal the subsurface damage(SSD)of 4H-SiC wafers by photo-chemical etching and identify the nature of SSD by molten-alkali etching.Under UV illumination,SSD acts as a photoluminescence-black defect.The selective photo-chemical etching reveals SSD as the ridge-like defect.It is found that the ridge-like SSD is still crystalline 4H-SiC with lattice distortion.The molten-KOH etching of the 4H-SiC wafer with ridge-like SSD transforms the ridge-like SSD into groove lines,which are typical features of scratches.This means that the underlying scratches under mechanical stress give rise to the formation of SSD in 4H-SiC wafers.SSD is incorporated into 4H-SiC wafers during the lapping,rather than the chemical mechanical polishing(CMP).

Preliminary study on modelling, fabrication by photo-chemical etching and in vivo testing of biodegradable magnesium AZ31 stents

Magnesium metal(Mg)is a promising material for stent applications due to its biocompatibility and ability to be resorbed by the body.Manufacturing of stents by laser cutting has become an industry standard.Our alternative approach uses photo-chemical etching to transfer a pattern of the stent onto a Mg sheet.In this study,we present three stages of creating and validating a stent prototype,which includes design and simulation using finite element analysis(FEA),followed by fabrication based on AZ31 alloy and,finally,in vivo testing in peripheral arteries of domestic pigs.Due to the preliminary character of this study,only six stents were implanted in two domestic farm pigs weighing 25-28 kg and they were evaluated after 28 days,with an interim follow-up on day 14.The left and right superficial femoral,the left iliac,and the right renal artery were selected for this study.The diameters of the stented artery segments were evaluated at the time of implantation,on day 14 and then,finally,on day 28,by quantitative vessel analysis(QVA)using fluoroscopic imaging.Optical Coherence Tomography(OCT)imaging displayed some malposition,breaks,stacking,and protrusion into the lumen at the proximal,distal,and mid-sections of the stented arteries.The stents degraded with time,but simultaneously became embedded in the intima.After 28 days,the animals were euthanized,and explanted vessels were fixed for micro-CT imaging and histology studies.Micro-CT imaging revealed stent morphological and volumetric changes due to the in-body degradation.An in vivo corrosion rate of 0.75 mm/year was obtained by the CT evaluation.The histology suggested no-life threatening effects,although moderate injury,inflammation,and endothelialization scores were observed.

Efficient degradation of orange II by ZnMn2O4 in a novel photo-chemical catalysis system

A ZnMn2O4 catalyst has been synthesized via a sucrose-aided combustion method and characterized by various analytical techniques.It is composed of numerous nanoparticles(15-110 nm)assembled into a porous structure with a specific surface area(SSA)o f 19.1 m^2.g^-1.Its catalytic activity has been investigated for the degradation of orange II dye using three different systems,i.e.,the photocatalysis system with visible light,the chemocatalysis system with bisulfite,and the photochemical catalysis system with both visible light and bisulfite.The last system exhibits the maximum degradation efficiency of 90%,much higher than the photocatalysis system(15%)and the chemocatalysis system(67%).The recycling experiments indicate that the ZnMn204 catalyst has high stability and reusability and is thus a green and eximious catalyst.Furthermore,the potential degradation mechanisms applicable to the three systems are discussed with relevant theoretical analysis and scavenging experiments for radicals.The active species such as Mn(III),o2^-,H^+,eaq,So4^- and Ho^-are proposed to be responsible for the excellent degradation results in the photo-chemical catalysis system with the ZnMn2o4 catalyst.

Can we suppress excessive post-surgical scar formation:A case report

BACKGROUND Hypertrophic scars(HSs)formation is a complication that occurs after wounds heal with secondary intention and sometimes after clean surgical incisions.Many treatments are in vogue now with varying successes.Although the mechanism or mechanisms that cause a HS to form are not clearly understood,one thing that is clear is that once scar tissue matures,any intervention will not be successful.In this paper,we report on a case where a patient who was known to develop HS was treated with a new combination of ingredients(Phyto-chemicals+Silicone JUMI)to suppress HS formation.CASE SUMMARY A 68-year-old female of African descent presented a severe HS post total knee replacement(TKR),which the patient describes as itchy and painful.Due to complications caused by the scar,she was apprehensive about undergoing TKR on her other knee.However,after the TKR of the contralateral side post-removal of skin clips,JUMI anti-scar cream(JASC)was used to suppress excessive scar formation.CONCLUSION JASC appears potent and efficacious at suppressing excessive scar formation.We believe that this warrants further studies on larger patient groups and on different surgical sites.

New photo-thermal-synthesized polymer for self-compacting concrete to increase productivity, minimize pollution, and eliminate steam curing in precast concrete

The objective in this study is to apply the sustainable chemistry and photo-thermal synthesis technology to produce the sustainable eco-superplasticiser for the sustainable high performance SCC concrete especially in hot tropical countries. A photo-thermal synthesized eco-superplasticiser （PSES） was produced by using photo-thermal catalyst in a solar chemical reactor. In this preliminary study, an unique high early strength of SCC concrete has been successfully produced by imposing an unique proportion of the photo-thermal-synthesized eco- Superplasticiser （PSES）, local fly ash, sand and aggregate. The SCC concrete is preliminary tried in the precast concrete product to produce the complicated geometries as Tunnel segment, U-shape beam, and Box girder which have the critical reinforcement and thin section concrete. Surprisingly, this SCC provide the benefits as eliminating steaming energy, increased productivity, and minimize pollution. These unique properties of sustainable SCC concrete can not be achieved by the convention concrete by using ligno, naphthalene and melamine base superplasficiser. The synthesized sustainable eco-superplasticiser is a perfect choice to fully utilized the renewable energy and improve the concrete working environment.

Synthesis and Properties of Photo-functional Hyperbranched Polymers

1 Results UV curing systems have been widely used in various industries such as coatings,printing inks,and photo-resists,because of their low volatile organic compound (VOC),excellent physical properties,and energy saving.Recently,these systems have also been applied to electronics and information technology fields such as display,CD,DVD,optical-fiber,and optical-device. In these curing systems,(meth)acrylate oligomers are mainly used due to their high photochemical reactivity. Recently,dendritic polyme...