Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded ...Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station (AWS) was -58.3℃ in 2005 and -58.2℃ in 2006, re-spectively. The 10-m firn temperature is an approximation of the annual mean air temperature (AMAT), and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios (δ 18O and δ D) of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the "pole of cold" on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.展开更多
Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas, which are easily matched and int...Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas, which are easily matched and integrated with the circuits of rectennas. The double-layer structure not only minimizes the size of the rectennas but also decreases the effects of the circuits on the an- tenna. The receiving elements have broader bandwidth and higher gain than the single-layer patches. Two rectennas operating at 10GHz are designed, fabricated and measured. The voltage of 3.86V on a load of 200? is measured and a high RF-DC conversion efficiency of 75% is obtained at 9.98GHz. It is convenient for this kind of rectennas to form large arrays for high power applications.展开更多
Voltage-dependent anion channel （VDAC）I is the main channel of the mitochondrial outer membrane （MOM） and it has been proposed to be part of the permeability transition pore （PTP）, a putative multiprotein comple...Voltage-dependent anion channel （VDAC）I is the main channel of the mitochondrial outer membrane （MOM） and it has been proposed to be part of the permeability transition pore （PTP）, a putative multiprotein complex candidate agent of the mitochondrial permeability transition （MPT）. Working at the single live cell level, we found that overexpression of VDAC1 triggers MPT at the mitochondrial inner membrane （MIM）. Conversely, silencing VDAC1 ex- pression results in the inhibition of MPT caused by selenite-induced oxidative stress. This MOM-MIM crosstalk was modulated by Cyclosporin A and mitochondrial Cyclophilin D, but not by Bcl-2 and BcI-XL, indicative of PTP operation. VDAC1-dependent MPT engages a positive feedback loop involving reactive oxygen species and p38-MAPK, and secondarily triggers a canonical apoptotic response including Bax activation, cytochrome e release and caspase 3 activation. Our data thus support a model of the PTP complex involving VDAC1 at the MOM, and indicate that VDACl-dependent MPT is an upstream mechanism playing a causal role in oxidative stress-induced apoptosis.展开更多
Excitation（ Texc ） and rotation（ Trot ） temperatures were determined under different conditions for an oxygen-shielded argon microwave plasmsa torch source（OS-Ar-MPT）. The Texc value, which was shown to be betwe...Excitation（ Texc ） and rotation（ Trot ） temperatures were determined under different conditions for an oxygen-shielded argon microwave plasmsa torch source（OS-Ar-MPT）. The Texc value, which was shown to be between 4300 and 5250 K under different operating conditions, was calculated from the slope of the Boltzmann plot with Fe as the thermometric species. The Trot value, which was in the range of 2100-2500 K, was measured with OH molecular spectra. The influences of microwave power, flow rates of the support gas, cartier gas, and shielding gas, as well as the observation height on Texc and Trot were investigated and discussed. The detailed results of Texc and Trot provided a better understanding of the performance of an OS-ArMPT as a source for atomic emission spectrometry.展开更多
基金the National Natural Science Foundation of China (Grant Nos. 40620120112 and 40776002)Chinese Academy of Sciences (Grant No. KZCX-SW-354)the Hundred-Talent Project of Chinese Academy of Sciences
文摘Lowest temperature and snow accumulation rate are preconditions for retrieving the oldest ice core from the polar ice sheets. The 10-m depth firn temperature at Dome A, the summit of the Antarctic Ice Sheet, recorded by an automatic weather station (AWS) was -58.3℃ in 2005 and -58.2℃ in 2006, re-spectively. The 10-m firn temperature is an approximation of the annual mean air temperature (AMAT), and this is the lowest AMAT that has been recorded on the surface of the Earth. The stable isotopic ratios (δ 18O and δ D) of surface snow at Dome A are also lower than at other ice sheet domes along the East Antarctic Ice Divide such as Dome C, Dome F, Dome B and Vostok. These facts indicate that Dome A is the "pole of cold" on the Earth. The total amount of snow accumulation rate in 2005 and 2006 was only 0.16 cm, equaling 0.016 m water equivalent per year, the lowest precipitation ever recorded from Antarctica. Preliminary evidences indicate that Dome A is a candidate site for recovering the oldest ice core.
基金Supported by the Development Fund of Shanghai Edu-cation Committee and Shanghai Leading Academic Dis-cipline Project (No.T0102)
文摘Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas, which are easily matched and integrated with the circuits of rectennas. The double-layer structure not only minimizes the size of the rectennas but also decreases the effects of the circuits on the an- tenna. The receiving elements have broader bandwidth and higher gain than the single-layer patches. Two rectennas operating at 10GHz are designed, fabricated and measured. The voltage of 3.86V on a load of 200? is measured and a high RF-DC conversion efficiency of 75% is obtained at 9.98GHz. It is convenient for this kind of rectennas to form large arrays for high power applications.
文摘Voltage-dependent anion channel （VDAC）I is the main channel of the mitochondrial outer membrane （MOM） and it has been proposed to be part of the permeability transition pore （PTP）, a putative multiprotein complex candidate agent of the mitochondrial permeability transition （MPT）. Working at the single live cell level, we found that overexpression of VDAC1 triggers MPT at the mitochondrial inner membrane （MIM）. Conversely, silencing VDAC1 ex- pression results in the inhibition of MPT caused by selenite-induced oxidative stress. This MOM-MIM crosstalk was modulated by Cyclosporin A and mitochondrial Cyclophilin D, but not by Bcl-2 and BcI-XL, indicative of PTP operation. VDAC1-dependent MPT engages a positive feedback loop involving reactive oxygen species and p38-MAPK, and secondarily triggers a canonical apoptotic response including Bax activation, cytochrome e release and caspase 3 activation. Our data thus support a model of the PTP complex involving VDAC1 at the MOM, and indicate that VDACl-dependent MPT is an upstream mechanism playing a causal role in oxidative stress-induced apoptosis.
基金Supported by the Science and Technology Development Program of Jilin Province, P. R. China(No. 20010306-1).
文摘Excitation（ Texc ） and rotation（ Trot ） temperatures were determined under different conditions for an oxygen-shielded argon microwave plasmsa torch source（OS-Ar-MPT）. The Texc value, which was shown to be between 4300 and 5250 K under different operating conditions, was calculated from the slope of the Boltzmann plot with Fe as the thermometric species. The Trot value, which was in the range of 2100-2500 K, was measured with OH molecular spectra. The influences of microwave power, flow rates of the support gas, cartier gas, and shielding gas, as well as the observation height on Texc and Trot were investigated and discussed. The detailed results of Texc and Trot provided a better understanding of the performance of an OS-ArMPT as a source for atomic emission spectrometry.
