Using the 3-year observational data from ChinaFlux （Chinese Terrestrial Ecosystem Flux Research Network）, we studied the gas regulation flux dynamics and cumulative process of gas regulation value in Qianyanzhou mid...Using the 3-year observational data from ChinaFlux （Chinese Terrestrial Ecosystem Flux Research Network）, we studied the gas regulation flux dynamics and cumulative process of gas regulation value in Qianyanzhou middle subtropical plantation （QYF） and Changbai Mountain temperate mixed forest （CBF）. The gas regulation service was differentiated into vegetation gas regulation service and net ecosystem gas regulation service. Carbon tax approach, reforestation cost approach and industrial oxygen approach were employed to calculate gas regulation value. Results show that there was significant seasonal variation in vegetation gas regulation flux. Daily CO2 uptake fluxes averaged 82.00 kg·ha^-·d^-1 and 59.37 kg·ha^-·d^-1 and the corresponding 02 emission fluxes were 59.65 kg·ha^-·d^-1 and 43.19 kg·ha^-·d^-1 for QYF and CBF, respectively. The cumulative curves of vegetation gas regulation value always followed a sigmoid shape, and the annual gas regulation value produced by vegetation was RMB 14342.69 yuan·ha^-1 and RMB 10384.18 yuan·ha^-1 for both QYF and CBF, respectively. In terms of monthly net ecosystem gas regulation service, QYF appeared as a CO2 sink and O2 source for the whole year, while CBF appeared to be a CO2 sink and O2 source mainly in the period between May and September. The cumulative curves of net ecosystem gas regulation value presented a sigmoid （＂S＂） shape for QYF, while a unimodal type curve for CBF. The annual net ecosystem gas regulation value was 8470.52 yuan·ha^-1 and 5091.98yuan·ha^-1 for QYF and CBF, respectively. The economic value of both the vegetation gas regulation service and net ecosystem gas regulation service were mainly produced between May and October.展开更多
Soil samples were taken from depth of 0-12 cm in virgin broad-leaved Korean pine mixed forest in Changbai Moun-tain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3- on N2O emission and C...Soil samples were taken from depth of 0-12 cm in virgin broad-leaved Korean pine mixed forest in Changbai Moun-tain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3- on N2O emission and CH4 uptake of a for-est soil were studied in laboratory by the method of orthogonal design. It was observed under laboratory conditions in this study that there were significant correlations between N2O emission rate, CH4 oxidation rate, soil pH and temperature. Nevertheless, N2O emission rate also showed a significant positive correlation with CH4 oxidation rate. The results suggested that pH and temperature were important factors controlling N2O emission and CH4 oxidation under this experiment conditions.展开更多
Biofouling is an important factor that affects bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitor...Biofouling is an important factor that affects bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitors for food resource with the cultured species. The present study was conducted to measure the impact of fouling on food uptake and nutrient release in April, 2006 in Daya Bay near Guangzhou, China. Results showed that fouling organisms had significant effect on food uptake and nutrient release. The chlorophyll a uptake rate of fouled scallops was 7.53 / Lh ±1.416 / Lh in April, significantly higher than those of cleaned scallops, Le., 4.23 / Lh±2.744 / Lh. The consumption of total particulate matter by fouled scallops in April was 5.52 / Lh± 0.818 / Lh; the corresponding results for cleaned scallops are 2.49 / Lh ±0.614 / Lh Fouling increased ammonia release significantly. The ammonia release rate of fouled scallops was 33.81/Lh ±7.699 / Lh in April, while cleaned scallops released 2.46 / Lh ±0.511 / Lh ammonia. Phosphate uptake of fouled scallops was 2.01± 0.699 / Lh and cleaned scallops released phosphate 6.01 / Lh ＋ 0.876 / Lh in April. There was not significant difference in nitrate consumption between fouled and cleaned scallops. According to the phytoplankton classification of input and output water samples, fouled scallops filtered more phytoplankton species than cleaned scallops. Therefore, this study showed that fouling contributed much to phytoplankton depletion and concentration increase of ammonia in water.展开更多
A high gain cascade connected preamplifier for optical receivers is developed with 0.5μm GaAs PHEMT technology from the Nanjing Electronic Devices Institute. To begin with, the transimpedance amplifier has a -3dB ban...A high gain cascade connected preamplifier for optical receivers is developed with 0.5μm GaAs PHEMT technology from the Nanjing Electronic Devices Institute. To begin with, the transimpedance amplifier has a -3dB bandwidth of 10GHz, with a small signal gain of around 9dB. The post-stage distributed amplifier （DA） has a -3dB bandwidth of close to 20GHz,with a small signal gain of around 12dB. As a whole,the cascade preamplifier has a measured small signal gain of 21.3dB and a transimpedance of 55.3dBΩ in a 50Ω system. With a higher signal-to-noise ratio than that of the TIA and a markedly improved waveform distortion compared with that of the DA, the measured output eye diagram for 10Gb/s NRZ pseudorandom binary sequence is clear and symmetric.展开更多
This paper presents a 12-channel,30Gb/s front-end amplifier realized in standard 0.18μm CMOS technology for parallel optlc-fiber receivers. In order to overcome the problem of inadequate bandwidth caused by the large...This paper presents a 12-channel,30Gb/s front-end amplifier realized in standard 0.18μm CMOS technology for parallel optlc-fiber receivers. In order to overcome the problem of inadequate bandwidth caused by the large parasitical capacitor of CMOS photo-detectors,a regulated-cascode structure and noise optimization are used in the design of the transimpedance amplifier. The experimental results indicate that, with a parasitical capacitance of 2pF,a single channel is able to work at bite rates of up to 2.5Gb/s,and a clear eye diagram is obtained with a 0. 8mVpp input. Furthermore, an isolation structure combined with a p^＋ guard.ring （PGR）, an n^＋ guard-ring （NGR）,and a deep-n-well （DNW） for parallel amplifier is also presented. Taking this combined structure, the crosstalk and the substrate noise coupling have been effectively reduced. Compared with the isolation of PGR or PGR ＋ NGR,the measured results show that the isolation degree of this structure is improved by 29.2 and 8. ldB at 1GHz,and by 8. 1 and 2. 5dB at 2GHz,respectively. With a 1.8V supply,each channel of the front-end amplifier consumes a DC power of 85mW,and the total power consumption of 12 channels is about 1W.展开更多
A 0. 5mV high sensitivity,200Mbps CMOS limiting amplifier （LA） with 72dB ultra wide dynamic range is described. A novel active DC offset cancellation loop is elaborately analyzed and designed to achieve this perform...A 0. 5mV high sensitivity,200Mbps CMOS limiting amplifier （LA） with 72dB ultra wide dynamic range is described. A novel active DC offset cancellation loop is elaborately analyzed and designed to achieve this performance. Using a signal path, a received signal strength indicator （RSSI）, based on the piecewise-linear approximation, is realized with a ± 2dB logarithmic accuracy in a 60dB indicating range. The architecture of the LA and RSSI employed is determined by the optimal sensitivity and RSSI accuracy for a specified speed, gain, and power consumption. It consumes 60mW from a single 5V supply. The active area is 1.05mm^2 using standard 5V 0.6μm CMOS technology.展开更多
A 2. 4GHz CMOS monolithic transceiver front-end for IEEE 802. llb wireless LAN applications is presented. The receiver and transmitter are both of superheterodyne structure for good system performance. The frontend co...A 2. 4GHz CMOS monolithic transceiver front-end for IEEE 802. llb wireless LAN applications is presented. The receiver and transmitter are both of superheterodyne structure for good system performance. The frontend consists of five blocks., low noise amplifier,down-converter, up-converter, pre-amplifier, and LO buffer. Their input/output impedance are all on-chip matched to 50 Ω except the down-converter which has open-drain outputs. The transceiver RF front-end has been implemented in a 0. 18μm CMOS process. When the LNA and the down-converter are directly connected, the measured noise figure is 5.2dB, the measured available power gain 12. 5dB, the input l dB compression point --18dBm,and the third-order input intercept point --7dBm. The receiver front-end draws 13.6mA currents from the 1.8V power supply. When the up-converter and pre-amplifier are directly connected, the measured noise figure is 12.4dB, the power gain is 23. 8dB, the output ldB compression point is 1.5dBm, and the third-order output intercept point is 16dBm. The transmitter consumes 27.6mA current from the 1.8V power supply.展开更多
The sorption-desorption behavior of dicyandiamide (DCD) is an importantchemical process that affects DCD fate and mobility in soils. Therefore, this study quantified DCDsorption-desorption on a phaeozem (Mollisol), a ...The sorption-desorption behavior of dicyandiamide (DCD) is an importantchemical process that affects DCD fate and mobility in soils. Therefore, this study quantified DCDsorption-desorption on a phaeozem (Mollisol), a burozem (Alfisol), a soil with organicmatter-removed and peat humus using the batch-equilibration procedure, and identified soilproperties that influenced DCD sorption. The sorption on peat humus was higher than that on thephaeozem and the burozem, with much lower sorption observed on the soil with organic matter-removed,indicating that soil organic matter was the main carrier of DCD sorption. Due to its amphipathicproperty the DCD molecule sorption on the phaeozem and the burozem decreased as pH increased fromabout 2 to 5, but a further increase in pH led to a rise in DCD sorption. The DCD desorptionhysteretic effect for peat humus was greater than that for the phaeozem and the burozem using 0.01mol L^(-1) CaCl_2 as the background electrolyte, suggesting that the hydrophobic domains of organicmatter may play an important role in DCD sorption.展开更多
A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymm...A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.展开更多
The liver plays a central role in iron metabolism. It is the major storage site for iron and also expresses a complex range of molecules which are involved in iron transport and regulation of iron homeostasis. An incr...The liver plays a central role in iron metabolism. It is the major storage site for iron and also expresses a complex range of molecules which are involved in iron transport and regulation of iron homeostasis. An increasing number of genes associated with hepatic iron transport or regulation have been identified. These include transferrin receptors （TFRI and 2）, a ferrireductase （STEAP3）, the transporters divalent metal transporter-1 （DMT1） and ferroportin （FPN） as well as the haemochromatosis protein, HFE and haemojuvelin （HJV）, which are signalling molecules. Many of these genes also participate in iron regulatory pathways which focus on the hepatic peptide hepcidin. However, we are still only beginning to understand the complex interactions between liver iron transport and iron homeostasis. This review outlines our current knowledge of molecules of iron metabolism and their roles in iron transport and regulation of iron homeostasis.展开更多
A broadband amplifier with transadmittance and transimpedance stages is designed and two types of improved AGC amplifiers are developed on the base of theory study. Making use of the basic amplifier cells, a main ampl...A broadband amplifier with transadmittance and transimpedance stages is designed and two types of improved AGC amplifiers are developed on the base of theory study. Making use of the basic amplifier cells, a main amplifier IC for optical-fiber receivers is deliberated. By computer simulating the performances of the designed main amplifier meet the necessity of high gain and wide dynamic range . They are maximum voltage gain of 42 dB, the bandwidth of 730 MHz,the input signal( V p-p )range from 5 mV to 1 V,the output amplitude about 1 V, the dynamic range of 46 dB. The designed circuit containing no inductance and large capacitance will be convenient for realizing integration. A monolithic integrated design of 622 Mb/s main amplifier is completed.展开更多
基金Chinese Terrestrial Ecosystem Flux Observational Research Network(ChinaFlux) for providing the observational data
文摘Using the 3-year observational data from ChinaFlux （Chinese Terrestrial Ecosystem Flux Research Network）, we studied the gas regulation flux dynamics and cumulative process of gas regulation value in Qianyanzhou middle subtropical plantation （QYF） and Changbai Mountain temperate mixed forest （CBF）. The gas regulation service was differentiated into vegetation gas regulation service and net ecosystem gas regulation service. Carbon tax approach, reforestation cost approach and industrial oxygen approach were employed to calculate gas regulation value. Results show that there was significant seasonal variation in vegetation gas regulation flux. Daily CO2 uptake fluxes averaged 82.00 kg·ha^-·d^-1 and 59.37 kg·ha^-·d^-1 and the corresponding 02 emission fluxes were 59.65 kg·ha^-·d^-1 and 43.19 kg·ha^-·d^-1 for QYF and CBF, respectively. The cumulative curves of vegetation gas regulation value always followed a sigmoid shape, and the annual gas regulation value produced by vegetation was RMB 14342.69 yuan·ha^-1 and RMB 10384.18 yuan·ha^-1 for both QYF and CBF, respectively. In terms of monthly net ecosystem gas regulation service, QYF appeared as a CO2 sink and O2 source for the whole year, while CBF appeared to be a CO2 sink and O2 source mainly in the period between May and September. The cumulative curves of net ecosystem gas regulation value presented a sigmoid （＂S＂） shape for QYF, while a unimodal type curve for CBF. The annual net ecosystem gas regulation value was 8470.52 yuan·ha^-1 and 5091.98yuan·ha^-1 for QYF and CBF, respectively. The economic value of both the vegetation gas regulation service and net ecosystem gas regulation service were mainly produced between May and October.
基金This paper was supported by Chinese Academy of Sciences.
文摘Soil samples were taken from depth of 0-12 cm in virgin broad-leaved Korean pine mixed forest in Changbai Moun-tain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3- on N2O emission and CH4 uptake of a for-est soil were studied in laboratory by the method of orthogonal design. It was observed under laboratory conditions in this study that there were significant correlations between N2O emission rate, CH4 oxidation rate, soil pH and temperature. Nevertheless, N2O emission rate also showed a significant positive correlation with CH4 oxidation rate. The results suggested that pH and temperature were important factors controlling N2O emission and CH4 oxidation under this experiment conditions.
基金supported by National Science Foundation of Huaihai Institute of Technology (No. KQ07102)Open Project Program of the Key Laboratory of Marine Bio-resources Sustainable Utilization, SCSIO, CAS (No. KK09001)
文摘Biofouling is an important factor that affects bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitors for food resource with the cultured species. The present study was conducted to measure the impact of fouling on food uptake and nutrient release in April, 2006 in Daya Bay near Guangzhou, China. Results showed that fouling organisms had significant effect on food uptake and nutrient release. The chlorophyll a uptake rate of fouled scallops was 7.53 / Lh ±1.416 / Lh in April, significantly higher than those of cleaned scallops, Le., 4.23 / Lh±2.744 / Lh. The consumption of total particulate matter by fouled scallops in April was 5.52 / Lh± 0.818 / Lh; the corresponding results for cleaned scallops are 2.49 / Lh ±0.614 / Lh Fouling increased ammonia release significantly. The ammonia release rate of fouled scallops was 33.81/Lh ±7.699 / Lh in April, while cleaned scallops released 2.46 / Lh ±0.511 / Lh ammonia. Phosphate uptake of fouled scallops was 2.01± 0.699 / Lh and cleaned scallops released phosphate 6.01 / Lh ＋ 0.876 / Lh in April. There was not significant difference in nitrate consumption between fouled and cleaned scallops. According to the phytoplankton classification of input and output water samples, fouled scallops filtered more phytoplankton species than cleaned scallops. Therefore, this study showed that fouling contributed much to phytoplankton depletion and concentration increase of ammonia in water.
文摘A high gain cascade connected preamplifier for optical receivers is developed with 0.5μm GaAs PHEMT technology from the Nanjing Electronic Devices Institute. To begin with, the transimpedance amplifier has a -3dB bandwidth of 10GHz, with a small signal gain of around 9dB. The post-stage distributed amplifier （DA） has a -3dB bandwidth of close to 20GHz,with a small signal gain of around 12dB. As a whole,the cascade preamplifier has a measured small signal gain of 21.3dB and a transimpedance of 55.3dBΩ in a 50Ω system. With a higher signal-to-noise ratio than that of the TIA and a markedly improved waveform distortion compared with that of the DA, the measured output eye diagram for 10Gb/s NRZ pseudorandom binary sequence is clear and symmetric.
文摘This paper presents a 12-channel,30Gb/s front-end amplifier realized in standard 0.18μm CMOS technology for parallel optlc-fiber receivers. In order to overcome the problem of inadequate bandwidth caused by the large parasitical capacitor of CMOS photo-detectors,a regulated-cascode structure and noise optimization are used in the design of the transimpedance amplifier. The experimental results indicate that, with a parasitical capacitance of 2pF,a single channel is able to work at bite rates of up to 2.5Gb/s,and a clear eye diagram is obtained with a 0. 8mVpp input. Furthermore, an isolation structure combined with a p^＋ guard.ring （PGR）, an n^＋ guard-ring （NGR）,and a deep-n-well （DNW） for parallel amplifier is also presented. Taking this combined structure, the crosstalk and the substrate noise coupling have been effectively reduced. Compared with the isolation of PGR or PGR ＋ NGR,the measured results show that the isolation degree of this structure is improved by 29.2 and 8. ldB at 1GHz,and by 8. 1 and 2. 5dB at 2GHz,respectively. With a 1.8V supply,each channel of the front-end amplifier consumes a DC power of 85mW,and the total power consumption of 12 channels is about 1W.
文摘A 0. 5mV high sensitivity,200Mbps CMOS limiting amplifier （LA） with 72dB ultra wide dynamic range is described. A novel active DC offset cancellation loop is elaborately analyzed and designed to achieve this performance. Using a signal path, a received signal strength indicator （RSSI）, based on the piecewise-linear approximation, is realized with a ± 2dB logarithmic accuracy in a 60dB indicating range. The architecture of the LA and RSSI employed is determined by the optimal sensitivity and RSSI accuracy for a specified speed, gain, and power consumption. It consumes 60mW from a single 5V supply. The active area is 1.05mm^2 using standard 5V 0.6μm CMOS technology.
文摘A 2. 4GHz CMOS monolithic transceiver front-end for IEEE 802. llb wireless LAN applications is presented. The receiver and transmitter are both of superheterodyne structure for good system performance. The frontend consists of five blocks., low noise amplifier,down-converter, up-converter, pre-amplifier, and LO buffer. Their input/output impedance are all on-chip matched to 50 Ω except the down-converter which has open-drain outputs. The transceiver RF front-end has been implemented in a 0. 18μm CMOS process. When the LNA and the down-converter are directly connected, the measured noise figure is 5.2dB, the measured available power gain 12. 5dB, the input l dB compression point --18dBm,and the third-order input intercept point --7dBm. The receiver front-end draws 13.6mA currents from the 1.8V power supply. When the up-converter and pre-amplifier are directly connected, the measured noise figure is 12.4dB, the power gain is 23. 8dB, the output ldB compression point is 1.5dBm, and the third-order output intercept point is 16dBm. The transmitter consumes 27.6mA current from the 1.8V power supply.
基金Project supported by the National High Technology Research and Development Program of China (863 Program) (No. 2004AA246020) the National Natural Science Foundation for Distinguished Young Scholars, China(No. 20225722).
文摘The sorption-desorption behavior of dicyandiamide (DCD) is an importantchemical process that affects DCD fate and mobility in soils. Therefore, this study quantified DCDsorption-desorption on a phaeozem (Mollisol), a burozem (Alfisol), a soil with organicmatter-removed and peat humus using the batch-equilibration procedure, and identified soilproperties that influenced DCD sorption. The sorption on peat humus was higher than that on thephaeozem and the burozem, with much lower sorption observed on the soil with organic matter-removed,indicating that soil organic matter was the main carrier of DCD sorption. Due to its amphipathicproperty the DCD molecule sorption on the phaeozem and the burozem decreased as pH increased fromabout 2 to 5, but a further increase in pH led to a rise in DCD sorption. The DCD desorptionhysteretic effect for peat humus was greater than that for the phaeozem and the burozem using 0.01mol L^(-1) CaCl_2 as the background electrolyte, suggesting that the hydrophobic domains of organicmatter may play an important role in DCD sorption.
文摘A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.
基金The National Health and Medical Research Council of Australia
文摘The liver plays a central role in iron metabolism. It is the major storage site for iron and also expresses a complex range of molecules which are involved in iron transport and regulation of iron homeostasis. An increasing number of genes associated with hepatic iron transport or regulation have been identified. These include transferrin receptors （TFRI and 2）, a ferrireductase （STEAP3）, the transporters divalent metal transporter-1 （DMT1） and ferroportin （FPN） as well as the haemochromatosis protein, HFE and haemojuvelin （HJV）, which are signalling molecules. Many of these genes also participate in iron regulatory pathways which focus on the hepatic peptide hepcidin. However, we are still only beginning to understand the complex interactions between liver iron transport and iron homeostasis. This review outlines our current knowledge of molecules of iron metabolism and their roles in iron transport and regulation of iron homeostasis.
文摘A broadband amplifier with transadmittance and transimpedance stages is designed and two types of improved AGC amplifiers are developed on the base of theory study. Making use of the basic amplifier cells, a main amplifier IC for optical-fiber receivers is deliberated. By computer simulating the performances of the designed main amplifier meet the necessity of high gain and wide dynamic range . They are maximum voltage gain of 42 dB, the bandwidth of 730 MHz,the input signal( V p-p )range from 5 mV to 1 V,the output amplitude about 1 V, the dynamic range of 46 dB. The designed circuit containing no inductance and large capacitance will be convenient for realizing integration. A monolithic integrated design of 622 Mb/s main amplifier is completed.
