The physics of electrodeless electric thrusters that use directed plasma to propel spacecraft without employing electrodes subject to plasma erosion is reviewed. Electrodeless plasma thrusters are potentially more dur...The physics of electrodeless electric thrusters that use directed plasma to propel spacecraft without employing electrodes subject to plasma erosion is reviewed. Electrodeless plasma thrusters are potentially more durable than presently deployed thrusters that use electrodes such as gridded ion,Hall thrusters, arcjets and resistojets. Like other plasma thrusters, electrodeless thrusters have the advantage of reduced fuel mass compared to chemical thrusters that produce the same thrust. The status of electrodeless plasma thrusters that could be used in communications satellites and in spacecraft for interplanetary missions is examined. Electrodeless thrusters under development or planned for deployment include devices that use a rotating magnetic field; devices that use a rotating electric field; pulsed inductive devices that exploit the Lorentz force on an induced current loop in a plasma; devices that use radiofrequency fields to heat plasmas and have magnetic nozzles to accelerate the hot plasma and other devices that exploit the Lorentz force. Using metrics of specific impulse and thrust efficiency, we find that the most promising designs are those that use Lorentz forces directly to expel plasma and those that use magnetic nozzles to accelerate plasma.展开更多
The alumina composite coatings reinforced with 25% ZrO2 （denoted as AZ-25） and 3% TiO2 （denoted as AT-3） were deposited on low carbon steel using a thermal flame spraying. The microstructure, phase composition, mi...The alumina composite coatings reinforced with 25% ZrO2 （denoted as AZ-25） and 3% TiO2 （denoted as AT-3） were deposited on low carbon steel using a thermal flame spraying. The microstructure, phase composition, microhardness and tribological properties of the coatings were investigated. The XRD results of the coatings reinforced by TiO2 （AT-3） revealed the presence of α-Al2O3 phase as matrix and new metastable phases of α-Al2O3 and α-Al2O3. However, the coatings reinforced by ZrO2 （AZ-25） consist of α-Al2O3 as matrix, q-ZrO2 and m-ZrO2. In most studied conditions, the AT-3 coating displays a better tribological performance, i.e., lower coefficient of frictions and wear rates, than the AZ-25 coating. It was also found that the microhardness of the coatings was decreased with the reinforcement of ZrO2 and increased with TiO2.展开更多
Hepatitis B virus (HBV) infection is still a public health problem worldwide, being endemic in some parts of the world. It can lead to serious liver diseases such as chronic hepatitis, cirrhosis, and hepatocellular ca...Hepatitis B virus (HBV) infection is still a public health problem worldwide, being endemic in some parts of the world. It can lead to serious liver diseases such as chronic hepatitis, cirrhosis, and hepatocellular cancer. The differences in host immune response can be one of the reasons for the various clinical presentations of HBV infection. Polymorphisms of genes encoding the proinflammatory and antiinflammatory cytokines, which are responsible for regulation of the immune response, can affect the clinical presentation of the infection. Particularly, the polymorphisms of the genes encoding cytokines such as interleukin (IL)-1, IL-6, IL-8, IL-10, IL-18, IL-28B, interferon-γ, tumor necrosis factor-α, tumor growth factor-β1, and regulatory molecules like vitamin D receptor and chemokine receptor 5 can be responsible for different clinical presentations of HBV infections. The genomic information about cytokines and other mediators can be important for determining high-risk people for developing chronic hepatitis or hepatocellular cancer and may be used to plan treatment and preventive approaches for these people. In this review, the current knowledge in the literature on the association between cytokine/regulatory molecule gene polymorphisms and clinical course of chronic HBV infection is summarized, and the clinical implementations and future prospects regarding this knowledge are discussed.展开更多
Many biological structures such as nerves,blood and lymphatic vessels,and muscle fibres exhibit longitudinal ge-ometries with distinct cell types extending along both the length and width of internal linear axes.Model...Many biological structures such as nerves,blood and lymphatic vessels,and muscle fibres exhibit longitudinal ge-ometries with distinct cell types extending along both the length and width of internal linear axes.Modelling these three-dimensional structures in vitro is challenging:the best-defined stem-cell differentiation systems are mono-layer cultures or organoids using pluripotent stem cells.Pluripotent stem cells can differentiate into functionally mature cells depending on the signals received,holding great promise for regenerative medicine.However,the integration of in vitro differentiated cell types into diseased tissue remains a challenge.Engineered scaffolds can bridge this gap if the appropriate signalling systems are incorporated into the scaffold.Here,we have taken a biomimicry approach to generate longitudinal structures in vitro.In this approach,mouse embryonic stem cells are directed to differentiate to specific cell types on the surface of polycaprolactone(PCL)fibres treated by plasma-immersion ion implantation and to which with lineage-specifying molecules have been covalently im-mobilised.We demonstrate the simplicity and utility of our method for efficiently generating high yields of the following cell types from these pluripotent stem cells:neurons,vascular endothelial cells,osteoclasts,adipocytes,and cells of the erythroid,myeloid,and lymphoid lineages.Strategically arranged plasma-treated scaffolds with differentiated cell types could ultimately serve as a means for the repair or treatment of diseased or damaged tissue.展开更多
The highly organized extracellular matrix(ECM)of musculoskeletal tissues,encompassing tendons,ligaments and muscles,is structurally anisotropic,hierarchical and multi-compartmental.These features collectively contribu...The highly organized extracellular matrix(ECM)of musculoskeletal tissues,encompassing tendons,ligaments and muscles,is structurally anisotropic,hierarchical and multi-compartmental.These features collectively contribute to their unique function.Previous studies have investigated the effect of tissue-engineered scaffold anisotropy on cell morphology and organization for musculoskeletal tissue repair and regeneration,but the hierarchical arrangement of ECM and compartmentalization are not typically replicated.Here,we present a method for multi-compartmental scaffold design that allows for physical mimicry of the spatial architecture of musculoskeletal tissue in regenerative medicine.This design is based on an ECM-inspired macromolecule scaffold.Polycaprolactone(PCL)scaffolds were fabricated with aligned fibers by electrospinning and mechanical stretching,and then surface-functionalized with the cell-supporting ECM protein molecule,tropoelastin(TE).TE was attached using two alternative methods that allowed for either physisorption or covalent attachment,where the latter was achieved by plasma ion immersion implantation(PIII).Aligned fibers stimulated cell elongation and improved cell alignment,in contrast to randomly oriented fibers.TE coatings bound by physisorption or covalently following 200 s PIII treatment promoted fibroblast proliferation.This represents the first cytocompatibility assessment of novel PIII-treated TE-coated PCL scaffolds.To demonstrate their versatility,these 2D anisotropic PCL scaffolds were assembled into 3D hierarchical constructs with an internally compartmentalized structure to mimic the structure of musculoskeletal tissue.展开更多
基金The financial support of the Australian Research Council for this projectthe provision of an Australian Postgraduate Award
文摘The physics of electrodeless electric thrusters that use directed plasma to propel spacecraft without employing electrodes subject to plasma erosion is reviewed. Electrodeless plasma thrusters are potentially more durable than presently deployed thrusters that use electrodes such as gridded ion,Hall thrusters, arcjets and resistojets. Like other plasma thrusters, electrodeless thrusters have the advantage of reduced fuel mass compared to chemical thrusters that produce the same thrust. The status of electrodeless plasma thrusters that could be used in communications satellites and in spacecraft for interplanetary missions is examined. Electrodeless thrusters under development or planned for deployment include devices that use a rotating magnetic field; devices that use a rotating electric field; pulsed inductive devices that exploit the Lorentz force on an induced current loop in a plasma; devices that use radiofrequency fields to heat plasmas and have magnetic nozzles to accelerate the hot plasma and other devices that exploit the Lorentz force. Using metrics of specific impulse and thrust efficiency, we find that the most promising designs are those that use Lorentz forces directly to expel plasma and those that use magnetic nozzles to accelerate plasma.
文摘The alumina composite coatings reinforced with 25% ZrO2 （denoted as AZ-25） and 3% TiO2 （denoted as AT-3） were deposited on low carbon steel using a thermal flame spraying. The microstructure, phase composition, microhardness and tribological properties of the coatings were investigated. The XRD results of the coatings reinforced by TiO2 （AT-3） revealed the presence of α-Al2O3 phase as matrix and new metastable phases of α-Al2O3 and α-Al2O3. However, the coatings reinforced by ZrO2 （AZ-25） consist of α-Al2O3 as matrix, q-ZrO2 and m-ZrO2. In most studied conditions, the AT-3 coating displays a better tribological performance, i.e., lower coefficient of frictions and wear rates, than the AZ-25 coating. It was also found that the microhardness of the coatings was decreased with the reinforcement of ZrO2 and increased with TiO2.
文摘Hepatitis B virus (HBV) infection is still a public health problem worldwide, being endemic in some parts of the world. It can lead to serious liver diseases such as chronic hepatitis, cirrhosis, and hepatocellular cancer. The differences in host immune response can be one of the reasons for the various clinical presentations of HBV infection. Polymorphisms of genes encoding the proinflammatory and antiinflammatory cytokines, which are responsible for regulation of the immune response, can affect the clinical presentation of the infection. Particularly, the polymorphisms of the genes encoding cytokines such as interleukin (IL)-1, IL-6, IL-8, IL-10, IL-18, IL-28B, interferon-γ, tumor necrosis factor-α, tumor growth factor-β1, and regulatory molecules like vitamin D receptor and chemokine receptor 5 can be responsible for different clinical presentations of HBV infections. The genomic information about cytokines and other mediators can be important for determining high-risk people for developing chronic hepatitis or hepatocellular cancer and may be used to plan treatment and preventive approaches for these people. In this review, the current knowledge in the literature on the association between cytokine/regulatory molecule gene polymorphisms and clinical course of chronic HBV infection is summarized, and the clinical implementations and future prospects regarding this knowledge are discussed.
基金supported by the Australian Research Council Laureate and Discovery fundings[FL190100216,DP190103507 and DE210100662]the University of Sydney School of Physics“Grand Challenge”program.
文摘Many biological structures such as nerves,blood and lymphatic vessels,and muscle fibres exhibit longitudinal ge-ometries with distinct cell types extending along both the length and width of internal linear axes.Modelling these three-dimensional structures in vitro is challenging:the best-defined stem-cell differentiation systems are mono-layer cultures or organoids using pluripotent stem cells.Pluripotent stem cells can differentiate into functionally mature cells depending on the signals received,holding great promise for regenerative medicine.However,the integration of in vitro differentiated cell types into diseased tissue remains a challenge.Engineered scaffolds can bridge this gap if the appropriate signalling systems are incorporated into the scaffold.Here,we have taken a biomimicry approach to generate longitudinal structures in vitro.In this approach,mouse embryonic stem cells are directed to differentiate to specific cell types on the surface of polycaprolactone(PCL)fibres treated by plasma-immersion ion implantation and to which with lineage-specifying molecules have been covalently im-mobilised.We demonstrate the simplicity and utility of our method for efficiently generating high yields of the following cell types from these pluripotent stem cells:neurons,vascular endothelial cells,osteoclasts,adipocytes,and cells of the erythroid,myeloid,and lymphoid lineages.Strategically arranged plasma-treated scaffolds with differentiated cell types could ultimately serve as a means for the repair or treatment of diseased or damaged tissue.
基金supported by an Australian Commonwealth Government Research Training Program Tuition Fee Offset and Stipend Scholarship.A.S.W.acknowledges funding from the National Health and Medical Research Council(APP1195827)M.M.M.B.acknowledges funding from the Australian Research Council(FL190100216).
文摘The highly organized extracellular matrix(ECM)of musculoskeletal tissues,encompassing tendons,ligaments and muscles,is structurally anisotropic,hierarchical and multi-compartmental.These features collectively contribute to their unique function.Previous studies have investigated the effect of tissue-engineered scaffold anisotropy on cell morphology and organization for musculoskeletal tissue repair and regeneration,but the hierarchical arrangement of ECM and compartmentalization are not typically replicated.Here,we present a method for multi-compartmental scaffold design that allows for physical mimicry of the spatial architecture of musculoskeletal tissue in regenerative medicine.This design is based on an ECM-inspired macromolecule scaffold.Polycaprolactone(PCL)scaffolds were fabricated with aligned fibers by electrospinning and mechanical stretching,and then surface-functionalized with the cell-supporting ECM protein molecule,tropoelastin(TE).TE was attached using two alternative methods that allowed for either physisorption or covalent attachment,where the latter was achieved by plasma ion immersion implantation(PIII).Aligned fibers stimulated cell elongation and improved cell alignment,in contrast to randomly oriented fibers.TE coatings bound by physisorption or covalently following 200 s PIII treatment promoted fibroblast proliferation.This represents the first cytocompatibility assessment of novel PIII-treated TE-coated PCL scaffolds.To demonstrate their versatility,these 2D anisotropic PCL scaffolds were assembled into 3D hierarchical constructs with an internally compartmentalized structure to mimic the structure of musculoskeletal tissue.
