Lung transplantation is the treatment of choice for patients with end-stage lung disease.Currently,just under 5000 lung transplants are performed worldwide annually.However,a major scourge leading to 90-d and 1-year m...Lung transplantation is the treatment of choice for patients with end-stage lung disease.Currently,just under 5000 lung transplants are performed worldwide annually.However,a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction.It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant.This review aims to provide an in-depth analysis of the epidemiology,pathophysiology,risk factors,outcomes,and future frontiers involved in mitigating primary graft dysfunction.The current diagnostic criteria are examined alongside changes from the previous definition.We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion.Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality,ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.展开更多
High-speed micromilling （spindle speeds 100 000r/min） can create complex three-dimensional microfeaturesin difficult-to-machine materials. The micromachined sur-face must be of high quatity, to meet functional requi...High-speed micromilling （spindle speeds 100 000r/min） can create complex three-dimensional microfeaturesin difficult-to-machine materials. The micromachined sur-face must be of high quatity, to meet functional require-ments. However, chatter-induced dynamic instabilitydeteriorates the surface quality and can be detrimental totool life. Chatter-free machining can be accomplished byidentifying stable process parameters via stability lobe dia-gram. To generate accurate stability lobe diagram, it isessential to determine the microend mill dynamics. Fre-quency response function is required to determine the tool-tip dynamics obtained by experimental impact analysis.Note that application of impact load at the microend mill tip（typically 100 - 500 μm） is not feasible as it would invari-ably end with tool failure. Consequently, alternative meth-ods need to be developed to identify the microend milldynamics. In the present work, the frequency responsefunction for the microend mill is obtained by finite elementmethod modal analysis. The frequency response functionobtained from modal analysis has been verified from theexperimentally obtained frequency response function. Theexperimental frequency response function was obtained byimpacting the microend mill near the taper portion with animpact hammer and measuring the vibration of the tool-tipwith a laser displacement sensor. The fundamental fre-quency obtained from finite element method modal analysisshows a difference of 6.6% from the experimental funda-mental frequency. Microend mill dynamics obtained fromthe finite element method is used for chatter prediction inhigh-speed micromilling operations. The stability lobe dia-gram predicts the stability boundary accurately at 60 000r/min and 80 000 r/min; however, a slight deviation isobserved at 100 000 r/min.展开更多
Engineered features on pyrolytic carbon （PyC） have been reported to improve the functional performance of the bio-implants. This paper is focused on the functional characterization of micro-features created on the s...Engineered features on pyrolytic carbon （PyC） have been reported to improve the functional performance of the bio-implants. This paper is focused on the functional characterization of micro-features created on the surface of PyC. Two different types of micro-features （wide channels and arrayed holes） have been created by micro-electrical discharge machining （micro-EDM）. Two other micro-fea- tures （fine channels and micro-pillars） have been created by micromilling process. Coliform bacterial strain was iso- lated from a sample of water and grown on all four tex- tured. Cell growth was carried out on an unmachined surface to see the behavior of the isolated bacterial strain on the textured/non-textured surfaces. The samples were examined under SEM before and after wash to see cell growth and cell adhesion capability of the textures. The wide channels by micro-EDM show the maximum cell growth but poor cell adhesion. 184% higher cell growth has been observed on the wide channels in comparison with unmachined surface. The fine channels by micro-milling show comparatively lower growth but the cell adhesion on this surface was found excellent. 71% cells remain unwa- shed after washing of the surface having fine channel textures. It means that the channels structure shows the maximum cell growth and adhesion independent of machining process.展开更多
文摘Lung transplantation is the treatment of choice for patients with end-stage lung disease.Currently,just under 5000 lung transplants are performed worldwide annually.However,a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction.It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant.This review aims to provide an in-depth analysis of the epidemiology,pathophysiology,risk factors,outcomes,and future frontiers involved in mitigating primary graft dysfunction.The current diagnostic criteria are examined alongside changes from the previous definition.We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion.Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality,ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.
文摘High-speed micromilling （spindle speeds 100 000r/min） can create complex three-dimensional microfeaturesin difficult-to-machine materials. The micromachined sur-face must be of high quatity, to meet functional require-ments. However, chatter-induced dynamic instabilitydeteriorates the surface quality and can be detrimental totool life. Chatter-free machining can be accomplished byidentifying stable process parameters via stability lobe dia-gram. To generate accurate stability lobe diagram, it isessential to determine the microend mill dynamics. Fre-quency response function is required to determine the tool-tip dynamics obtained by experimental impact analysis.Note that application of impact load at the microend mill tip（typically 100 - 500 μm） is not feasible as it would invari-ably end with tool failure. Consequently, alternative meth-ods need to be developed to identify the microend milldynamics. In the present work, the frequency responsefunction for the microend mill is obtained by finite elementmethod modal analysis. The frequency response functionobtained from modal analysis has been verified from theexperimentally obtained frequency response function. Theexperimental frequency response function was obtained byimpacting the microend mill near the taper portion with animpact hammer and measuring the vibration of the tool-tipwith a laser displacement sensor. The fundamental fre-quency obtained from finite element method modal analysisshows a difference of 6.6% from the experimental funda-mental frequency. Microend mill dynamics obtained fromthe finite element method is used for chatter prediction inhigh-speed micromilling operations. The stability lobe dia-gram predicts the stability boundary accurately at 60 000r/min and 80 000 r/min; however, a slight deviation isobserved at 100 000 r/min.
文摘Engineered features on pyrolytic carbon （PyC） have been reported to improve the functional performance of the bio-implants. This paper is focused on the functional characterization of micro-features created on the surface of PyC. Two different types of micro-features （wide channels and arrayed holes） have been created by micro-electrical discharge machining （micro-EDM）. Two other micro-fea- tures （fine channels and micro-pillars） have been created by micromilling process. Coliform bacterial strain was iso- lated from a sample of water and grown on all four tex- tured. Cell growth was carried out on an unmachined surface to see the behavior of the isolated bacterial strain on the textured/non-textured surfaces. The samples were examined under SEM before and after wash to see cell growth and cell adhesion capability of the textures. The wide channels by micro-EDM show the maximum cell growth but poor cell adhesion. 184% higher cell growth has been observed on the wide channels in comparison with unmachined surface. The fine channels by micro-milling show comparatively lower growth but the cell adhesion on this surface was found excellent. 71% cells remain unwa- shed after washing of the surface having fine channel textures. It means that the channels structure shows the maximum cell growth and adhesion independent of machining process.
