The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material behaviors under high strain rate loading condition. Attempts to apply the Split Hopkison Pressu...The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material behaviors under high strain rate loading condition. Attempts to apply the Split Hopkison Pressure Bar in measurement on polymeric materials suffer from limitations on the maximum achievable strain and from high noise to signal ratios. This paper introduces a Split Hopkinson Pressure Bar technique, to overcome these limitations. The proposed method uses aluminum pressure bars to achieve a closer impedance match between the pressure bars and the specimen materials, thus providing both data having a low noise to signal ratio and a longer input pulse at higher maximum strain. In addition, a pulse shaper technique was used for increasing the rise time of the incident pulse to ensure stress equilibrium and homogeneous deformation in the specimen under dynamic compression. A pulse shaper is utilized to lengthen the rising time of the incident pulse to ensure stress equilibrium and homogeneous deformation of polycarbonate. The dynamic deformation behaviors of Polymeric material under compressive high strain rate are evaluated using the modified SHPB technique.展开更多
A mounting body of evidence indicates that dietary fiber(DF)metabolites produced by commensal bacteria play essential roles in balancing the immune system.DF,considered nonessential nutrients in the past,is now consid...A mounting body of evidence indicates that dietary fiber(DF)metabolites produced by commensal bacteria play essential roles in balancing the immune system.DF,considered nonessential nutrients in the past,is now considered to be necessary to maintain adequate levels of immunity and suppress inflammatory and allergic responses.Short-chain fatty acids(SCFAs),such as acetate,propionate,and butyrate,are the major DF metabolites and mostly produced by specialized commensal bacteria that are capable of breaking down DF into simpler saccharides and further metabolizing the saccharides into SCFAs.SCFAs act on many cell types to regulate a number of important biological processes,including host metabolism,intestinal functions,and immunity system.This review specifically highlights the regulatory functions of DF and SCFAs in the immune system with a focus on major innate and adaptive lymphocytes.Current information regarding how SCFAs regulate innate lymphoid cells,T helper cells,cytotoxic T cells,and B cells and how these functions impact immunity,inflammation,and allergic responses are discussed.展开更多
Benign prostatic hyperplasia(BPH)is characterized by an enlarged prostate,lower urinary tract symptoms(LUTS),and a decreased urinary flow rate.Common in older men,BPH is a progressive disease that can eventually lead ...Benign prostatic hyperplasia(BPH)is characterized by an enlarged prostate,lower urinary tract symptoms(LUTS),and a decreased urinary flow rate.Common in older men,BPH is a progressive disease that can eventually lead to complications including acute urinary retention(AUR)and the need for BPH-related surgery.Both normal and abnormal prostate growth is driven by the androgen dihydrotestosterone(DHT),which is formed from testosterone under the influence of 5-alpha reductase.Thus,5-alpha reductase inhibitors(5-ARIs)effectively reduce the serum and intraprostatic concentration of DHT,causing an involution of prostate tissue.Two 5-ARIs are currently available for the treatment of BPHdfinasteride and dutasteride.Both have been demonstrated to decrease prostate volume,improve LUTS and urinary flow rates,which ultimately reduces the risk of AUR and BPH-related surgery.Therefore,either alone or in combination with other BPH medications,5-ARIs are a mainstay of BPH management.展开更多
Aim:To determine whether in utero and neonatal exposure to a 60 Hz extremely low frequency electromagnetic field (EMF) results in spermatotoxicity and reproductive dysfunction in the F1 offspring of rats.Methods:Age-m...Aim:To determine whether in utero and neonatal exposure to a 60 Hz extremely low frequency electromagnetic field (EMF) results in spermatotoxicity and reproductive dysfunction in the F1 offspring of rats.Methods:Age-matched, pregnant Sprague-Dawley rats were exposed continuously (21 h/day) to a 60 Hz EMF at field strengths of 0 (sham control),5,83.3 or 500 μT from day 6 of gestation through to day 21 of lactation.The experimentally generated magnetic field was monitored continuously (uninterrupted monitoring over the period of the study) throughout the study.Results:No exposure-related changes were found in exposed or sham-exposed animals with respect to the anogenital distance,preputial separation,testis weight,testicular histology,sperm count,daily sperm production, sperm motility,sperm morphology and reproductive capacity of F1 offspring.Conclusion:Exposure of Sprague- Dawley rats to a 60 Hz EMF at field strengths of up to 500 μT from day 6 of gestation to day 21 of lactation did not produce any detectable alterations in offspring spermatogenesis and fertility.展开更多
Increased demand for compact devices leads to rapid development of miniaturized digital cameras.However,conventional camera modules contain multiple lenses along the optical axis to compensate for optical aberrations ...Increased demand for compact devices leads to rapid development of miniaturized digital cameras.However,conventional camera modules contain multiple lenses along the optical axis to compensate for optical aberrations that introduce technical challenges in reducing the total thickness of the camera module.Here,we report an ultrathin digital camera inspired by the vision principle of Xenos peckii,an endoparasite of paper wasps.The male Xenos peckii has an unusual visual system that exhibits distinct benefits for high resolution and high sensitivity,unlike the compound eyes found in most insects and some crustaceans.The biologically inspired camera features a sandwiched configuration of concave microprisms,microlenses,and pinhole arrays on a flat image sensor.The camera shows a field-of-view(FOV)of 68 degrees with a diameter of 3.4mm and a total track length of 1.4mm.The biologically inspired camera offers a new opportunity for developing ultrathin cameras in medical,industrial,and military fields.展开更多
The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations.However,this is quite challenging because of the heavy weight of the scintillator and s...The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations.However,this is quite challenging because of the heavy weight of the scintillator and silicon photodetectors.The weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic photodetectors.This study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer(~700 nm),owing to the symmetric backbone and highly soluble molecular structure of bithienopyrroledione.The ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density(Jd~10−10 A cm^(−2))at a negative bias(−2.0 V)while maintaining high responsivity(R=0.29 A W−1)even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D_(sh)^(*)=2.18×10^(13)Jones in the organic photodetectors.Printed organic photodetectors are developed by slot-die coating for use in X-ray detectors,which exhibit D_(sh)^(*)=2.73×10^(12)Jones with clear rising(0.26 s)and falling(0.29 s)response times upon X-ray irradiation.Detection reliability is also proven by linear response of the X-ray detector,and the X-ray detection limit is 3 mA.展开更多
The effective surface treatment method for steel insert composited with Al base metal by expendable pattern casting （EPC） process and the bonding interface between steel insert and Al base metal were investigated.It...The effective surface treatment method for steel insert composited with Al base metal by expendable pattern casting （EPC） process and the bonding interface between steel insert and Al base metal were investigated.It was found that Zn plating on steel insert was effective on improving the bonding property between steel insert and Al base metal in EPC process.Zn is thought to promote the formation of diffusion layer.But almost none content of Zn was observed in the boundary which had been plated on the steel insert.A diffusion layer consisting of Al,Si and Fe was formed at the insert/alloy interface and its hardness was higher than the steel insert as matter of course Al base metal.This layer turned out to be intermetallic compounds of Al-Si-Fe system.Higher pouring temperature promoted the diffusion of Fe into Al alloy,so Fe content in intermetallic layers increased at higher pouring temperature.The layer nearest to steel disappeared due to applied pressure.展开更多
Airframe maintenance is traditionally performed at scheduled maintenance stops.The decision to repair a fuselage panel is based on a fixed crack size threshold,which allows to ensure the aircraft safety until the next...Airframe maintenance is traditionally performed at scheduled maintenance stops.The decision to repair a fuselage panel is based on a fixed crack size threshold,which allows to ensure the aircraft safety until the next scheduled maintenance stop.With progress in sensor technology and data processing techniques,structural health monitoring（SHM） systems are increasingly being considered in the aviation industry.SHM systems track the aircraft health state continuously,leading to the possibility of planning maintenance based on an actual state of aircraft rather than on a fixed schedule.This paper builds upon a model-based prognostics framework that the authors developed in their previous work,which couples the Extended Kalman filter（EKF） with a firstorder perturbation（FOP） method.By using the information given by this prognostics method,a novel cost driven predictive maintenance（CDPM） policy is proposed,which ensures the aircraft safety while minimizing the maintenance cost.The proposed policy is formally derived based on the trade-off between probabilities of occurrence of scheduled and unscheduled maintenance.A numerical case study simulating the maintenance process of an entire fleet of aircrafts is implemented.Under the condition of assuring the same safety level,the CDPM is compared in terms of cost with two other maintenance policies：scheduled maintenance and threshold based SHM maintenance.The comparison results show CDPM could lead to significant cost savings.展开更多
4-1BB is an inducible receptor expressed on activated T cells,while its ligand,4-1BBL,is mainly expressed in antigen-presenting cells and macrophages[1,2].To the best of our knowledge,ligandmediated transactivation of...4-1BB is an inducible receptor expressed on activated T cells,while its ligand,4-1BBL,is mainly expressed in antigen-presenting cells and macrophages[1,2].To the best of our knowledge,ligandmediated transactivation of 4-1BB is responsible for the survival and immune effector functions of T cells.展开更多
Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper ...Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper investigates whether or not stratospheric intrusion and photochemistry play a significant role in the springtime ozone maximum over Northeast Asia, where ozone measurements are sparse. We examine how tropospheric ozone seasonalities over Naha （26°N, 128°E）, Kagoshima （31°N, 131°E）, and Pohang （36°N, 129°E）, which are located on the same meridional line, are related to the timing and location of the jet stream. The ozone seasonality shows a gradual increase from January to the maximum ozone month, which corresponds to April at Naha, May at Kagoshima, and June at Pohang. In order to examine the occurrence of stratospheric intrusion, we analyze a correlation between jet stream activity and tropospheric ozone seasonality. From these analyses, we did not find any favorable evidence supporting the hypothesis that the springtime enhancement may result from stratospheric intrusion. According to trajectory analysis for vertical and horizontal origins of the airmass, a gradual increasing tendency in ozone amounts from January until the onset of monsoon was similar to the increasing ozone formation tendency from winter to spring over China's Mainland, which has been observed during the build-up of tropospheric ozone over Central Europe in the winter-spring transition period due to photochemistry. Overall, the analyses suggest that photochemistry is the most important contributor to observed ozone seasonality over Northeast Asia.展开更多
Microstructural stability of a nickel base single crystal alloy DD8 has been investigated.Standard heat treated specimen showed good microstructural stability at 950℃.While under the as-cast condition,a kind of rod-l...Microstructural stability of a nickel base single crystal alloy DD8 has been investigated.Standard heat treated specimen showed good microstructural stability at 950℃.While under the as-cast condition,a kind of rod-like phase precipitated in the interdendritic region of as-cast specimen during thermal exposure.The phase,which has bcc structure,was enriched with Cr.Thermo-calc also predicted precipitation of a bcc phase at around 950℃.The Cr-rich bcc phase was considered asα-Cr and formed due to the segregation of Cr under the as-cast condition.展开更多
Carbon and boron have been considered to strengthen grain boundaries that might form during single crystal casting.In this study the effect of boron on solidification behavior and creep properties of the carbon doped ...Carbon and boron have been considered to strengthen grain boundaries that might form during single crystal casting.In this study the effect of boron on solidification behavior and creep properties of the carbon doped single crystal RR 2072 has been investigated.In order to understand solidification behavior with boron addition,the solid/liquid interface morphology and solidification microstructure were examined with solidification rate.The relationship between mi-crostructural evolution and creep properties of the carbon and boron modified single crystal has been also investigated.展开更多
The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is increasing.Ni-free Ti-based shape memory alloys are promising candidates fo...The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is increasing.Ni-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional properties.In this study,a wide content range of(0-15)wt%of low-cost,toxicity-free,and high-biocompatible Sn element was added to the Ti-8Mo(wt%)alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn alloys.By tailoring Sn content,desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn alloys.It was found that the increase in Sn content stabilized theβphase and a singleβphase was obtained at room temperature in Ti-8Mo-(13,15)Sn alloys.The addition of Sn modified the lattice parameters of theα″martensite andβphase and affected the lattice deformation stain ofβ→α″.The lattice deformation strain along the[011]βdirection was found to be decreased by-0.26%/wt%Sn.The room temperature superelasticity with a recovery strain of 3.1%and an elastic admissible strain of 1%was obtained in the Ti-8Mo-13Sn alloy.As Sn content increased to 15 wt%,a high elastic admissible strain of 1.56%and a recovery strain of 2.0%were obtained.These Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications.展开更多
We report the electrical detection of captured gases through measurement of the quantum tunneling characteristics of gas-mediated molecular junctions formed across nanogaps.The gas-sensing nanogap device consists of a...We report the electrical detection of captured gases through measurement of the quantum tunneling characteristics of gas-mediated molecular junctions formed across nanogaps.The gas-sensing nanogap device consists of a pair of vertically stacked gold electrodes separated by an insulating 6 nm spacer(~1.5 nm of sputteredα-Si and~4.5 nm ALD SiO2),which is notched~10 nm into the stack between the gold electrodes.The exposed gold surface is functionalized with a self-assembled monolayer(SAM)of conjugated thiol linker molecules.When the device is exposed to a target gas(1,5-diaminopentane),the SAM layer electrostatically captures the target gas molecules,forming a molecular bridge across the nanogap.The gas capture lowers the barrier potential for electron tunneling across the notched edge region,from~5 eV to~0.9 eV and establishes additional conducting paths for charge transport between the gold electrodes,leading to a substantial decrease in junction resistance.We demonstrated an output resistance change of>108 times upon exposure to 80 ppm diamine target gas as well as ultralow standby power consumption of<15 pW,confirming electron tunneling through molecular bridges for ultralow-power gas sensing.展开更多
This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attent...This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attention has been given to solid state lighting devices and their applications since they have attracted the most interest and are the most promising. Solid state lighting devices including white light emitting diodes （LEDs）, organic LEDs （OLEDs）, quantum-dot LEDs （QLEDs） and carbon-dot LEDs （CLEDs） are promising energy efficient lighting sources for displays and general lighting. However there is no universal solution that will give better performance and efficiency for all types of applications. LEDs are replacing traditional lamp,; for both general lighting and display applications, whereas OLEDs are finding their own special application,; in various areas. QLEDs and CLEDs have advantages such as high quantum yields, narrow emission spectra, tunable emission spectra and good stability over OLEDs, so applications for these devices are being extended to new types of lighting sources. There is a great dean of research on these materials and their processing technologies and the commercial viability of these technologies appears strong.展开更多
文摘The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material behaviors under high strain rate loading condition. Attempts to apply the Split Hopkison Pressure Bar in measurement on polymeric materials suffer from limitations on the maximum achievable strain and from high noise to signal ratios. This paper introduces a Split Hopkinson Pressure Bar technique, to overcome these limitations. The proposed method uses aluminum pressure bars to achieve a closer impedance match between the pressure bars and the specimen materials, thus providing both data having a low noise to signal ratio and a longer input pulse at higher maximum strain. In addition, a pulse shaper technique was used for increasing the rise time of the incident pulse to ensure stress equilibrium and homogeneous deformation in the specimen under dynamic compression. A pulse shaper is utilized to lengthen the rising time of the incident pulse to ensure stress equilibrium and homogeneous deformation of polycarbonate. The dynamic deformation behaviors of Polymeric material under compressive high strain rate are evaluated using the modified SHPB technique.
基金supported,in part,by the NIH(R01AI121302,R21AI14889801,R01AI074745,and R01AI080769)Kenneth and Judy Betz Professorship at the Mary H.Weiser Food Allergy Center at the University of Michigan to C.H.K.
文摘A mounting body of evidence indicates that dietary fiber(DF)metabolites produced by commensal bacteria play essential roles in balancing the immune system.DF,considered nonessential nutrients in the past,is now considered to be necessary to maintain adequate levels of immunity and suppress inflammatory and allergic responses.Short-chain fatty acids(SCFAs),such as acetate,propionate,and butyrate,are the major DF metabolites and mostly produced by specialized commensal bacteria that are capable of breaking down DF into simpler saccharides and further metabolizing the saccharides into SCFAs.SCFAs act on many cell types to regulate a number of important biological processes,including host metabolism,intestinal functions,and immunity system.This review specifically highlights the regulatory functions of DF and SCFAs in the immune system with a focus on major innate and adaptive lymphocytes.Current information regarding how SCFAs regulate innate lymphoid cells,T helper cells,cytotoxic T cells,and B cells and how these functions impact immunity,inflammation,and allergic responses are discussed.
文摘Benign prostatic hyperplasia(BPH)is characterized by an enlarged prostate,lower urinary tract symptoms(LUTS),and a decreased urinary flow rate.Common in older men,BPH is a progressive disease that can eventually lead to complications including acute urinary retention(AUR)and the need for BPH-related surgery.Both normal and abnormal prostate growth is driven by the androgen dihydrotestosterone(DHT),which is formed from testosterone under the influence of 5-alpha reductase.Thus,5-alpha reductase inhibitors(5-ARIs)effectively reduce the serum and intraprostatic concentration of DHT,causing an involution of prostate tissue.Two 5-ARIs are currently available for the treatment of BPHdfinasteride and dutasteride.Both have been demonstrated to decrease prostate volume,improve LUTS and urinary flow rates,which ultimately reduces the risk of AUR and BPH-related surgery.Therefore,either alone or in combination with other BPH medications,5-ARIs are a mainstay of BPH management.
文摘Aim:To determine whether in utero and neonatal exposure to a 60 Hz extremely low frequency electromagnetic field (EMF) results in spermatotoxicity and reproductive dysfunction in the F1 offspring of rats.Methods:Age-matched, pregnant Sprague-Dawley rats were exposed continuously (21 h/day) to a 60 Hz EMF at field strengths of 0 (sham control),5,83.3 or 500 μT from day 6 of gestation through to day 21 of lactation.The experimentally generated magnetic field was monitored continuously (uninterrupted monitoring over the period of the study) throughout the study.Results:No exposure-related changes were found in exposed or sham-exposed animals with respect to the anogenital distance,preputial separation,testis weight,testicular histology,sperm count,daily sperm production, sperm motility,sperm morphology and reproductive capacity of F1 offspring.Conclusion:Exposure of Sprague- Dawley rats to a 60 Hz EMF at field strengths of up to 500 μT from day 6 of gestation to day 21 of lactation did not produce any detectable alterations in offspring spermatogenesis and fertility.
基金supported by the National Research Foundation of Korea(NRF-2018029899 to KHJ,NRF-2016R1A2B2013031 to MHK)the National Science Foundation(NSF-IOS1456757,to EKB)in the United States.
文摘Increased demand for compact devices leads to rapid development of miniaturized digital cameras.However,conventional camera modules contain multiple lenses along the optical axis to compensate for optical aberrations that introduce technical challenges in reducing the total thickness of the camera module.Here,we report an ultrathin digital camera inspired by the vision principle of Xenos peckii,an endoparasite of paper wasps.The male Xenos peckii has an unusual visual system that exhibits distinct benefits for high resolution and high sensitivity,unlike the compound eyes found in most insects and some crustaceans.The biologically inspired camera features a sandwiched configuration of concave microprisms,microlenses,and pinhole arrays on a flat image sensor.The camera shows a field-of-view(FOV)of 68 degrees with a diameter of 3.4mm and a total track length of 1.4mm.The biologically inspired camera offers a new opportunity for developing ultrathin cameras in medical,industrial,and military fields.
基金granted by the Korea Research Institute of Chemical Technology(KRICT)of the Republic of Korea(No.2422-10)the National Research Foundation(NRF)(NRF-2021R1C1C2007445 and RS-2023-00280495)of Republic of Korea.
文摘The development of portable X-ray detectors is necessary for diagnosing fractures in unconscious patients in emergency situations.However,this is quite challenging because of the heavy weight of the scintillator and silicon photodetectors.The weight and thickness of X-ray detectors can be reduced by replacing the silicon layer with an organic photodetectors.This study presents a novel bithienopyrroledione-based polymer donor that exhibits excellent photodetection properties even in a thick photoactive layer(~700 nm),owing to the symmetric backbone and highly soluble molecular structure of bithienopyrroledione.The ability of bithienopyrroledione-based polymer donor to strongly suppress the dark current density(Jd~10−10 A cm^(−2))at a negative bias(−2.0 V)while maintaining high responsivity(R=0.29 A W−1)even at a thickness of 700 nm results in a maximum shot-noise-limited specific detectivity of D_(sh)^(*)=2.18×10^(13)Jones in the organic photodetectors.Printed organic photodetectors are developed by slot-die coating for use in X-ray detectors,which exhibit D_(sh)^(*)=2.73×10^(12)Jones with clear rising(0.26 s)and falling(0.29 s)response times upon X-ray irradiation.Detection reliability is also proven by linear response of the X-ray detector,and the X-ray detection limit is 3 mA.
文摘The effective surface treatment method for steel insert composited with Al base metal by expendable pattern casting （EPC） process and the bonding interface between steel insert and Al base metal were investigated.It was found that Zn plating on steel insert was effective on improving the bonding property between steel insert and Al base metal in EPC process.Zn is thought to promote the formation of diffusion layer.But almost none content of Zn was observed in the boundary which had been plated on the steel insert.A diffusion layer consisting of Al,Si and Fe was formed at the insert/alloy interface and its hardness was higher than the steel insert as matter of course Al base metal.This layer turned out to be intermetallic compounds of Al-Si-Fe system.Higher pouring temperature promoted the diffusion of Fe into Al alloy,so Fe content in intermetallic layers increased at higher pouring temperature.The layer nearest to steel disappeared due to applied pressure.
基金supported by UT-INSA Program(2013)the support of the China Scholarship Council(CSC)
文摘Airframe maintenance is traditionally performed at scheduled maintenance stops.The decision to repair a fuselage panel is based on a fixed crack size threshold,which allows to ensure the aircraft safety until the next scheduled maintenance stop.With progress in sensor technology and data processing techniques,structural health monitoring（SHM） systems are increasingly being considered in the aviation industry.SHM systems track the aircraft health state continuously,leading to the possibility of planning maintenance based on an actual state of aircraft rather than on a fixed schedule.This paper builds upon a model-based prognostics framework that the authors developed in their previous work,which couples the Extended Kalman filter（EKF） with a firstorder perturbation（FOP） method.By using the information given by this prognostics method,a novel cost driven predictive maintenance（CDPM） policy is proposed,which ensures the aircraft safety while minimizing the maintenance cost.The proposed policy is formally derived based on the trade-off between probabilities of occurrence of scheduled and unscheduled maintenance.A numerical case study simulating the maintenance process of an entire fleet of aircrafts is implemented.Under the condition of assuring the same safety level,the CDPM is compared in terms of cost with two other maintenance policies：scheduled maintenance and threshold based SHM maintenance.The comparison results show CDPM could lead to significant cost savings.
基金This study was supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(2022R1A2C1005463[BKC],2022R1C1C1010078[SHK],and 2022R1C1C1003152[CH]from MSIT)by the National Cancer Center of Korea(NCC)grant funded by the Ministry of Health and Welfare(NCC-2212450[CH]).
文摘4-1BB is an inducible receptor expressed on activated T cells,while its ligand,4-1BBL,is mainly expressed in antigen-presenting cells and macrophages[1,2].To the best of our knowledge,ligandmediated transactivation of 4-1BB is responsible for the survival and immune effector functions of T cells.
基金supported by Research Agency for Climate Science funded by Korea Meteorological Administration(RACS 2010-1011)
文摘Scientists have long debated the relative importance of tropospheric photochemical production versus stratospheric influx as causes of the springtime tropospheric ozone maximum over northern mid-latitudes. This paper investigates whether or not stratospheric intrusion and photochemistry play a significant role in the springtime ozone maximum over Northeast Asia, where ozone measurements are sparse. We examine how tropospheric ozone seasonalities over Naha （26°N, 128°E）, Kagoshima （31°N, 131°E）, and Pohang （36°N, 129°E）, which are located on the same meridional line, are related to the timing and location of the jet stream. The ozone seasonality shows a gradual increase from January to the maximum ozone month, which corresponds to April at Naha, May at Kagoshima, and June at Pohang. In order to examine the occurrence of stratospheric intrusion, we analyze a correlation between jet stream activity and tropospheric ozone seasonality. From these analyses, we did not find any favorable evidence supporting the hypothesis that the springtime enhancement may result from stratospheric intrusion. According to trajectory analysis for vertical and horizontal origins of the airmass, a gradual increasing tendency in ozone amounts from January until the onset of monsoon was similar to the increasing ozone formation tendency from winter to spring over China's Mainland, which has been observed during the build-up of tropospheric ozone over Central Europe in the winter-spring transition period due to photochemistry. Overall, the analyses suggest that photochemistry is the most important contributor to observed ozone seasonality over Northeast Asia.
文摘Microstructural stability of a nickel base single crystal alloy DD8 has been investigated.Standard heat treated specimen showed good microstructural stability at 950℃.While under the as-cast condition,a kind of rod-like phase precipitated in the interdendritic region of as-cast specimen during thermal exposure.The phase,which has bcc structure,was enriched with Cr.Thermo-calc also predicted precipitation of a bcc phase at around 950℃.The Cr-rich bcc phase was considered asα-Cr and formed due to the segregation of Cr under the as-cast condition.
文摘Carbon and boron have been considered to strengthen grain boundaries that might form during single crystal casting.In this study the effect of boron on solidification behavior and creep properties of the carbon doped single crystal RR 2072 has been investigated.In order to understand solidification behavior with boron addition,the solid/liquid interface morphology and solidification microstructure were examined with solidification rate.The relationship between mi-crostructural evolution and creep properties of the carbon and boron modified single crystal has been also investigated.
基金the Korean Ministry of Trade,Industry and Energy(Grant No.200116572).
文摘The demand for titanium alloys simultaneously having high elastic admissible strain and large recovery strain for bio-implant applications is increasing.Ni-free Ti-based shape memory alloys are promising candidates for obtaining the required multifunctional properties.In this study,a wide content range of(0-15)wt%of low-cost,toxicity-free,and high-biocompatible Sn element was added to the Ti-8Mo(wt%)alloy to study its effect on the superelastic recovery and mechanical properties of biomedical Ti-Mo-Sn alloys.By tailoring Sn content,desired multifunctional properties of high elastic admissible strain and room temperature superelasticity were achieved in the studied Ti-Mo-Sn alloys.It was found that the increase in Sn content stabilized theβphase and a singleβphase was obtained at room temperature in Ti-8Mo-(13,15)Sn alloys.The addition of Sn modified the lattice parameters of theα″martensite andβphase and affected the lattice deformation stain ofβ→α″.The lattice deformation strain along the[011]βdirection was found to be decreased by-0.26%/wt%Sn.The room temperature superelasticity with a recovery strain of 3.1%and an elastic admissible strain of 1%was obtained in the Ti-8Mo-13Sn alloy.As Sn content increased to 15 wt%,a high elastic admissible strain of 1.56%and a recovery strain of 2.0%were obtained.These Ti-Mo-Sn alloys with excellent multifunctional properties are promising candidates for bio-implant applications.
基金We would like to acknowledge the contributions of Prattaydeepta Kairy,Chayanjit Ghosh,and Navid Farhoudi for assisting with various aspects of the sensor testing.This work made use of University of Utah USTAR shared facilities supported,in part,by the MRSEC Program of NSF under Award No.DMR-1121252This work was sponsored under cooperative agreement HR0011-15-2-0049 of the DARPA N-ZERO programThis research work was also generously funded by the cooperative agreement of DE-AR0001064 of the ARPAE OPEN 2018 program(Program Manager Dr.David Babson)in the United States.We feel grateful for the generous technical and administrative support from the ARPAE technical support staff(Dr.David Lee and Dr.Mike Xiao-Zhu Fan).
文摘We report the electrical detection of captured gases through measurement of the quantum tunneling characteristics of gas-mediated molecular junctions formed across nanogaps.The gas-sensing nanogap device consists of a pair of vertically stacked gold electrodes separated by an insulating 6 nm spacer(~1.5 nm of sputteredα-Si and~4.5 nm ALD SiO2),which is notched~10 nm into the stack between the gold electrodes.The exposed gold surface is functionalized with a self-assembled monolayer(SAM)of conjugated thiol linker molecules.When the device is exposed to a target gas(1,5-diaminopentane),the SAM layer electrostatically captures the target gas molecules,forming a molecular bridge across the nanogap.The gas capture lowers the barrier potential for electron tunneling across the notched edge region,from~5 eV to~0.9 eV and establishes additional conducting paths for charge transport between the gold electrodes,leading to a substantial decrease in junction resistance.We demonstrated an output resistance change of>108 times upon exposure to 80 ppm diamine target gas as well as ultralow standby power consumption of<15 pW,confirming electron tunneling through molecular bridges for ultralow-power gas sensing.
文摘This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attention has been given to solid state lighting devices and their applications since they have attracted the most interest and are the most promising. Solid state lighting devices including white light emitting diodes （LEDs）, organic LEDs （OLEDs）, quantum-dot LEDs （QLEDs） and carbon-dot LEDs （CLEDs） are promising energy efficient lighting sources for displays and general lighting. However there is no universal solution that will give better performance and efficiency for all types of applications. LEDs are replacing traditional lamp,; for both general lighting and display applications, whereas OLEDs are finding their own special application,; in various areas. QLEDs and CLEDs have advantages such as high quantum yields, narrow emission spectra, tunable emission spectra and good stability over OLEDs, so applications for these devices are being extended to new types of lighting sources. There is a great dean of research on these materials and their processing technologies and the commercial viability of these technologies appears strong.
