Semiconductor quantum dots(QDs)have been demonstrated viable for efficient light emission applications,in particular for the emission of single photons on demand.However,the preparation of QDs emitting photons with pr...Semiconductor quantum dots(QDs)have been demonstrated viable for efficient light emission applications,in particular for the emission of single photons on demand.However,the preparation of QDs emitting photons with predefined and deterministic polarization vectors has proven arduous.Access to linearly polarized photons is essential for various applications.In this report,a novel concept to directly generate linearly-polarized photons is presented.This concept is based on InGaN QDs grown on top of elongated GaN hexagonal pyramids,by which the predefined elongation determines the polarization vectors of the emitted photons from the QDs.This growth scheme should allow fabrication of ultracompact arrays of photon emitters,with a controlled polarization direction for each individual emitter.展开更多
This work is aimed at investigating the friction and wear performance of different polymeric materials having potential for hydraulic system components under lubricated sliding conditions against a steel counter face....This work is aimed at investigating the friction and wear performance of different polymeric materials having potential for hydraulic system components under lubricated sliding conditions against a steel counter face.A pin-on-disc test configuration was used for the experimental study.The different polymeric materials selected for these studies were commercial polyimides(PI),polyether ether ketone(PEEK),and flouropolymers.Some of these materials were bulk materials whereas others were used as coatings applied on to the cast iron substrate.The tribological characteristics of the polymers were compared with a reference grey cast iron.The frictional characteristics were evaluated in both static and dynamic conditions.The results have shown that by using polymeric materials it is possible to reduce breakaway friction by an order of magnitude compared to grey cast iron.However,the breakaway friction increased significantly after the wear tests.The polymeric materials having lowest breakaway friction have shown the highest wear with the exception of the PEEK-PTFE coating which showed low wear.PI with graphite fillers also showed low wear but it resulted in relatively high friction.The carbon fibre reinforced materials resulted in unstable friction as well as higher wear compared to the PI materials with graphite fillers.展开更多
基金This work was mainly supported by the Nano-N consortium funded by the Swedish Foundation for Strategic ResearchWe also acknowledge support from the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University(Faculty Grant SFO-Mat-LiU#2009-00971)grants from the Swedish Research Council(VR)and the Knut and Alice Wallenberg Foundation.
文摘Semiconductor quantum dots(QDs)have been demonstrated viable for efficient light emission applications,in particular for the emission of single photons on demand.However,the preparation of QDs emitting photons with predefined and deterministic polarization vectors has proven arduous.Access to linearly polarized photons is essential for various applications.In this report,a novel concept to directly generate linearly-polarized photons is presented.This concept is based on InGaN QDs grown on top of elongated GaN hexagonal pyramids,by which the predefined elongation determines the polarization vectors of the emitted photons from the QDs.This growth scheme should allow fabrication of ultracompact arrays of photon emitters,with a controlled polarization direction for each individual emitter.
文摘This work is aimed at investigating the friction and wear performance of different polymeric materials having potential for hydraulic system components under lubricated sliding conditions against a steel counter face.A pin-on-disc test configuration was used for the experimental study.The different polymeric materials selected for these studies were commercial polyimides(PI),polyether ether ketone(PEEK),and flouropolymers.Some of these materials were bulk materials whereas others were used as coatings applied on to the cast iron substrate.The tribological characteristics of the polymers were compared with a reference grey cast iron.The frictional characteristics were evaluated in both static and dynamic conditions.The results have shown that by using polymeric materials it is possible to reduce breakaway friction by an order of magnitude compared to grey cast iron.However,the breakaway friction increased significantly after the wear tests.The polymeric materials having lowest breakaway friction have shown the highest wear with the exception of the PEEK-PTFE coating which showed low wear.PI with graphite fillers also showed low wear but it resulted in relatively high friction.The carbon fibre reinforced materials resulted in unstable friction as well as higher wear compared to the PI materials with graphite fillers.
