A 1.60μm laser diode and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter output for low-loss coupling to a cleaved single-mode optical fiber are demonstrated.The ...A 1.60μm laser diode and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter output for low-loss coupling to a cleaved single-mode optical fiber are demonstrated.The devices emit in a single transverse and quasi single longitudinal mode with an SMSR of 25.6dB.These devices exhibit a 3dB modulation bandwidth of 15.0GHz,and modulator DC extinction ratios of 16.2dB.The output beam divergence angles of the spot-size converter 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
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
A high-resolution,200kHz signal bandwidth,third-order single-loop single-bit ε△ modulator used in low-IF GSM receivers is presented. The modulator is implemented with fully differential switched capacitor circuits i...A high-resolution,200kHz signal bandwidth,third-order single-loop single-bit ε△ modulator used in low-IF GSM receivers is presented. The modulator is implemented with fully differential switched capacitor circuits in standard 0. 6μm 2P2M CMOS technology. The modulator uses two balanced reference voltages of ±1V,and is driven by a single 26MHz clock signal. The measurement results show that,with an oversampling ratio of 64, the modulator achieves an 80.6dB dynamic range,a 71.8dB peak SNDR,and a 73.9dB peak SNR in the signal bandwidth of 200kHz. The modulator dissipates 15mW static power from a single 5V supply.展开更多
AIM: To investigate the effect of adeno-associated virusmediated gene transfer of human endostatin on the growth of hepatocellular carcinoma (HCC).METHODS: HCC cell line Hep3B was infected with recombinantadeno-associ...AIM: To investigate the effect of adeno-associated virusmediated gene transfer of human endostatin on the growth of hepatocellular carcinoma (HCC).METHODS: HCC cell line Hep3B was infected with recombinantadeno-associated virus containing human endostatin gene (rAAV2-hEndo). The results of transfection were detected by RT-PCR and SDS-PAGE assay. MTT assay was used to observe the effects of supernatant of transfected cells on ECV304 cell proliferation. An animal model of HCC was established by injecting Hep3B cells subcutaneously into the back of nude mice. Intratumoral injection of rAAV2hEndo, empty virus and phosphate-buffered saline were given sequentially. Serum endostatin was determined byELISA, the inhibitory effect of endostatin on the growth of xenograft was assessed in 3 wk.RESULTS: The results of RT-PCR and SDS-PAGE assay confirmed that rAAV2-hEndo successfully transfected Hep3B cells, and endostatin was secreted from Hep3B cells to medium. The supernatant of transfected cells markedly inhibited the proliferation of ECV304 cells (P<0.01). Intratumoral injection of rAAV2-hEndo (2×1010v.g.) led to a sustained serum endostatin level ofapproximately (86.71±5.19) ng/mL. The tumor volumeand microvessel density were less in rAAV2-hEndo group than in control groups (P<0.01).CONCLUSION: Human endostatin can be stably expressed by adeno-associated virus-mediated gene transfer and effectively inhibit the growth of HCC.展开更多
A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis ...A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis and experiment results show the frequency difference method is a ideal power saving speed regulation method for the dou- ble inverter and motor system.The experiment system is simply structured,convenient to operate and provides a new way of character testing for frequency conversion speed regulation.展开更多
We propose a scheme of quantum computation with nonlinear quantum optics. Polarization states of photons are used for qubits. Photons with different frequencies represent different qubits. Single qubit rotation operat...We propose a scheme of quantum computation with nonlinear quantum optics. Polarization states of photons are used for qubits. Photons with different frequencies represent different qubits. Single qubit rotation operation is implemented through optical elements like the Faraday polarization rotator. Photons are separated into different optical paths, or merged into a single optical path using dichromatic mirrors. The controlled-NOT gate between two qubits is implemented by the proper combination of parametric up and down conversions. This scheme has the following features: (1) No auxiliary qubits are required in the controlled-NOT gate operation; (2) No measurement is required in the course of the computation; (3) It is resource efficient and conceptually simple.展开更多
In this paper,we discuss the unitary transformation induced by Z_6 rotations of noncommutative space onthe states |k,q,s〉,which plays a key role in construction for noncommutative solitons T^2/Z_6 by GHS method.As ar...In this paper,we discuss the unitary transformation induced by Z_6 rotations of noncommutative space onthe states |k,q,s〉,which plays a key role in construction for noncommutative solitons T^2/Z_6 by GHS method.As aresult,we prove a well-known 'Gauss Sum' formula in the number theory through a concise way.展开更多
A high-speed and high-resolution optical A/D quantizer is proposed.Its architecture is discussed.Bit circuits are built by using the phase modulators in parallel.Based on the different character of the half-wave volta...A high-speed and high-resolution optical A/D quantizer is proposed.Its architecture is discussed.Bit circuits are built by using the phase modulators in parallel.Based on the different character of the half-wave voltage for every phase modulator and the polarized bias design of incident light,the RF input signal is coled and transmitted in the form of optical digital signal.According to the principle of the architecture,the high-resolution quantizers with 8-bit and 12-bit,et al.are built,which operate at 100 GS/s.Their quantization noise is invariable almost with bit circuits increasing.The simulation result of 4-bit A/D quantizer is also given.展开更多
Based on the self-imaging effect, multimode interference (MMI) optical switches with area modulation were proposed. The field transfer matrix was introduced to analyze the MMI switches. As an example, the phase modula...Based on the self-imaging effect, multimode interference (MMI) optical switches with area modulation were proposed. The field transfer matrix was introduced to analyze the MMI switches. As an example, the phase modulation parameters of a 3 × 3 MMI switch for different switching cases were obtained by solving the field transfer equation. And the finite-difference beam propagation method (FD-BPM) was used to confirm the analytical results.展开更多
A novel optical-spectrum-encoded (OSE) analog-to-digital converter (ADC) is proposed in this letter. To simply exemplify the conversion idea, a 5-bit device structure consisted of Fabry-Perot interferometers (FPI...A novel optical-spectrum-encoded (OSE) analog-to-digital converter (ADC) is proposed in this letter. To simply exemplify the conversion idea, a 5-bit device structure consisted of Fabry-Perot interferometers (FPI) is analyzed and numericaly simulated. The dependence of peak-transmission wavelength on modulation voltage in an electro-optical FPI and the dependence of transmitted power on incident light wavelength in an FPI are discussed and utilized to implement OSEADC. A linearly tunable mode-locked laser, as a voltage-wavelength transformer and a sampler, and chirped grating FPIs, as an encoder array, can be used to obtain much greater sampling rate and bit-resolution.展开更多
Numerically analyzed is the transmission performance of the optical millimeter (mm)-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier(SC) signal...Numerically analyzed is the transmission performance of the optical millimeter (mm)-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier(SC) signals can be obtained after fiber transmission, simultaneously, the phase-modulated signals can be converted to the intensity-modulated ones. The numerical results show that the optical ram-wave at fading loops has better performance, and the eye diagram still keeps open when optical mm-wave signal is transmitted over 98 km.展开更多
Converters with pulse width modulation are used for connections between the direct current (DC) and alternating current (AC) networks, e.g., in uninterrupted power supply systems, AC electromotor drives, for power...Converters with pulse width modulation are used for connections between the direct current (DC) and alternating current (AC) networks, e.g., in uninterrupted power supply systems, AC electromotor drives, for powering induction furnaces, in audio technique. Spectrum of signals sampled by pulse amplitude modulation and output voltage spectrum of the converter with pulse width modulation have similar properties. Spectrum of signals sampled by pulse amplitude modulation contains a harmonic of frequency equal to the frequency of the modulating signal and the harmonics of frequencies equal to the sum of frequency of the modulating signal and multiples of the sampling frequency. The output voltage spectrum of the converter with bipolar pulse width modulation contains harmonic of frequency equal to the frequency of the modulating signal and harmonics of frequencies equal to sum of the frequency of the modulating signal and multiples of the frequency of the carrier signal. It also contains harmonics of frequencies equal to the sum of the multiples of the frequency of the modulating signal and the multiples of the carrier signal. The comparison analysis was carried out for the harmonics of the output voltage of the converter with bipolar pulse width modulation in time domain. The dependency of the amplitudes and frequency spectrum on the wave forms of the carrier signal and modulating signal was shown. Similarity of the output voltage spectrum of the converter and signal spectrum sampled by the pulse width modulation was also shown. Key words: Output voltage converter with bipolar pulse width modulation, spectral analysis, Fourier series, carrier signal, reference signal.展开更多
The electron paramagnetic resonance (EPR) parameters (zero-Geld splitting Dand g factors g_‖, g_⊥) of Cr~(4+) ions in Ca_2 GeO_4 crystals have been calculated from thecomplete high-order perturbation formulas of EPR...The electron paramagnetic resonance (EPR) parameters (zero-Geld splitting Dand g factors g_‖, g_⊥) of Cr~(4+) ions in Ca_2 GeO_4 crystals have been calculated from thecomplete high-order perturbation formulas of EPR parameters for a 3d~2 ion in trigonal MX_4clusters. In these formulas, in addition to the contributions to EPR parameters from the widely usedcrystal-field (CF) mechanism, the contributions from the charge-transfer (CT) mechanism (which areoften neglected) are included. From the calculations, it is found that for the high valence state3d~n ions in crystals, the reasonable explanation of EPR parameters (in particular, the g factors)should take both the CF and CT mechanisms into account.展开更多
This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD (adjustable speed drive). A conventional ASD with 2-level PWM (pulse width modulation) inverters generate hi...This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD (adjustable speed drive). A conventional ASD with 2-level PWM (pulse width modulation) inverters generate high dv/dt and high frequency common mode voltages which are harmful for the drive applications. It reduces the motor bearings life and conducted EMI (electro magnetic interference) deteriorates the insulation. In this paper, a diode clamped multilevel (3-level) inverter is used to perform dual task. It generates HF (high frequency) current to be injected at the input of the three-phase front-end rectifier thereby improving the harmonic spectra and the power factor. It also drives the induction motor. The salient feature of this paper is that it does not require separate converters for improving power factor and to drive induction motor. Furthermore, inverter switches operate with ZVS (zero voltage switching), thus reducing the switching losses substantially, The voltage stress of the switches also has been reduced to half of the conventional 2-level converter. The inverter is operated with SPWM (sinusoidal pulse width modulation) technique. The simulation results for a prototype of 2.2 kW are presented.展开更多
This paper introduces a high-revolution,200kHz signal bandwidth EA modulator for low-IF GSM receivers that adopts a 2-1 cascaded single-bit structure to achieve high linearity and stability. Our design is realized in ...This paper introduces a high-revolution,200kHz signal bandwidth EA modulator for low-IF GSM receivers that adopts a 2-1 cascaded single-bit structure to achieve high linearity and stability. Our design is realized in a standard 0.18μm CMOS process with art active area of 0.5mm× 1.1mm.The EA modulator is driven by a single 19.2MHz clock signal and dissipates 5.88mW from 3V power supply. The experimental results show that,with an oversampling ratio of 48, the modulator achieves a 84.4dB dynamic range,73.8dB peak SNDR, and 80dB peak SNR in the signal bandwidth of 200kHz.展开更多
For the main purpose of manipulating the functions of molecules, researchers have made great achievements on photoresponsive molecules using light as a trigger. Light has become a promising scientific tool due to it b...For the main purpose of manipulating the functions of molecules, researchers have made great achievements on photoresponsive molecules using light as a trigger. Light has become a promising scientific tool due to it being a clean and noninvasive external stimulant. By attachment of photoresponsive moieties to molecules, the biological activities of molecules can be attenuated by light activation. With wide applications of laser in life sciences, it will be possible to achieve high spatiotemporal resolution. In this review, we focus on photoresponsive nucleic acids for photomodulating gene expression with light activation. With incorporation of photoswitchable or photocleavable moieties, biological behaviors of nucleic acids are photoregulated reversibly or irreversibly. Recent development and applications of photoresponsive nucleic acid in vitro and in vivo have shown a very promising future for manipulation of specific functional genes or disease genes. We expect that photoresponsive nucleic acids will be powerful scientific tools for studying biological events as well as gene therapy agents for genetic diseases.展开更多
Skeletal muscle fitness plays vital roles in human health and disease and is determined by developmental as well as physiological inputs. These inputs control and coordinate muscle fiber programs, including capacity f...Skeletal muscle fitness plays vital roles in human health and disease and is determined by developmental as well as physiological inputs. These inputs control and coordinate muscle fiber programs, including capacity for fuel burning, mitochondrial ATP production, and contraction. Recent studies have demonstrated crucial roles for nuclear receptors and their co-activators, and micro RNAs(mi RNAs) in the regulation of skeletal muscle energy metabolism and fiber type determination. In this review, we present recent progress in the study of nuclear receptor signaling and mi RNA networks in muscle fiber type switching. We also discuss the therapeutic potential of nuclear receptors and mi RNAs in disease states that are associated with loss of muscle fitness.展开更多
We investigate the thermoelectric energy conversion efficiency of Si and Ge nanowires, and in particular, that of Si/Ge core-shell nanowires. We show how the presence of a thin Ge shell on a Si core nanowire increases...We investigate the thermoelectric energy conversion efficiency of Si and Ge nanowires, and in particular, that of Si/Ge core-shell nanowires. We show how the presence of a thin Ge shell on a Si core nanowire increases the overall figure of merit. We find the optimal thickness of the Ge shell to provide the largest figure of merit for the devices. We also consider Ge core/Si shell nanowires, and show that an optimal thickness of the Si shell does not exist, since the figure of merit is a monotonically decreasing function of the radius of the nanowire. Finally, we verify the empirical law relating the electron energy gap to the optimal working temperature that maximizes the efficiency of the device.展开更多
文摘A 1.60μm laser diode and electroabsorption modulator monolithically integrated with a novel dual-waveguide spot-size converter output for low-loss coupling to a cleaved single-mode optical fiber are demonstrated.The devices emit in a single transverse and quasi single longitudinal mode with an SMSR of 25.6dB.These devices exhibit a 3dB modulation bandwidth of 15.0GHz,and modulator DC extinction ratios of 16.2dB.The output beam divergence angles of the spot-size converter 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.
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.
文摘A high-resolution,200kHz signal bandwidth,third-order single-loop single-bit ε△ modulator used in low-IF GSM receivers is presented. The modulator is implemented with fully differential switched capacitor circuits in standard 0. 6μm 2P2M CMOS technology. The modulator uses two balanced reference voltages of ±1V,and is driven by a single 26MHz clock signal. The measurement results show that,with an oversampling ratio of 64, the modulator achieves an 80.6dB dynamic range,a 71.8dB peak SNDR,and a 73.9dB peak SNR in the signal bandwidth of 200kHz. The modulator dissipates 15mW static power from a single 5V supply.
基金Supported by the National Natural Science Foundation of China, No. 20074031
文摘AIM: To investigate the effect of adeno-associated virusmediated gene transfer of human endostatin on the growth of hepatocellular carcinoma (HCC).METHODS: HCC cell line Hep3B was infected with recombinantadeno-associated virus containing human endostatin gene (rAAV2-hEndo). The results of transfection were detected by RT-PCR and SDS-PAGE assay. MTT assay was used to observe the effects of supernatant of transfected cells on ECV304 cell proliferation. An animal model of HCC was established by injecting Hep3B cells subcutaneously into the back of nude mice. Intratumoral injection of rAAV2hEndo, empty virus and phosphate-buffered saline were given sequentially. Serum endostatin was determined byELISA, the inhibitory effect of endostatin on the growth of xenograft was assessed in 3 wk.RESULTS: The results of RT-PCR and SDS-PAGE assay confirmed that rAAV2-hEndo successfully transfected Hep3B cells, and endostatin was secreted from Hep3B cells to medium. The supernatant of transfected cells markedly inhibited the proliferation of ECV304 cells (P<0.01). Intratumoral injection of rAAV2-hEndo (2×1010v.g.) led to a sustained serum endostatin level ofapproximately (86.71±5.19) ng/mL. The tumor volumeand microvessel density were less in rAAV2-hEndo group than in control groups (P<0.01).CONCLUSION: Human endostatin can be stably expressed by adeno-associated virus-mediated gene transfer and effectively inhibit the growth of HCC.
文摘A power saving frequency difference controlling method was introduced by the double inverter and motor experiment system.The characters of the system under differ- ent loads were investigated.The theoretical analysis and experiment results show the frequency difference method is a ideal power saving speed regulation method for the dou- ble inverter and motor system.The experiment system is simply structured,convenient to operate and provides a new way of character testing for frequency conversion speed regulation.
基金The project supported by the National Fundamental Research Program under Grant No.2006CB921106National Natural Science Foundation of China under Grant Nos.10325521 and 10390160
文摘We propose a scheme of quantum computation with nonlinear quantum optics. Polarization states of photons are used for qubits. Photons with different frequencies represent different qubits. Single qubit rotation operation is implemented through optical elements like the Faraday polarization rotator. Photons are separated into different optical paths, or merged into a single optical path using dichromatic mirrors. The controlled-NOT gate between two qubits is implemented by the proper combination of parametric up and down conversions. This scheme has the following features: (1) No auxiliary qubits are required in the controlled-NOT gate operation; (2) No measurement is required in the course of the computation; (3) It is resource efficient and conceptually simple.
基金Supported by National Natural Science Foundation of China under Grant No.10575080
文摘In this paper,we discuss the unitary transformation induced by Z_6 rotations of noncommutative space onthe states |k,q,s〉,which plays a key role in construction for noncommutative solitons T^2/Z_6 by GHS method.As aresult,we prove a well-known 'Gauss Sum' formula in the number theory through a concise way.
基金Natural Science Foundation from Colleges and Universities of Jiangsu Province(04KJD140033)
文摘A high-speed and high-resolution optical A/D quantizer is proposed.Its architecture is discussed.Bit circuits are built by using the phase modulators in parallel.Based on the different character of the half-wave voltage for every phase modulator and the polarized bias design of incident light,the RF input signal is coled and transmitted in the form of optical digital signal.According to the principle of the architecture,the high-resolution quantizers with 8-bit and 12-bit,et al.are built,which operate at 100 GS/s.Their quantization noise is invariable almost with bit circuits increasing.The simulation result of 4-bit A/D quantizer is also given.
基金Supported by the Scientific Research Startup Foundation of shenzhen University under Grant No. 200506.
文摘Based on the self-imaging effect, multimode interference (MMI) optical switches with area modulation were proposed. The field transfer matrix was introduced to analyze the MMI switches. As an example, the phase modulation parameters of a 3 × 3 MMI switch for different switching cases were obtained by solving the field transfer equation. And the finite-difference beam propagation method (FD-BPM) was used to confirm the analytical results.
文摘A novel optical-spectrum-encoded (OSE) analog-to-digital converter (ADC) is proposed in this letter. To simply exemplify the conversion idea, a 5-bit device structure consisted of Fabry-Perot interferometers (FPI) is analyzed and numericaly simulated. The dependence of peak-transmission wavelength on modulation voltage in an electro-optical FPI and the dependence of transmitted power on incident light wavelength in an FPI are discussed and utilized to implement OSEADC. A linearly tunable mode-locked laser, as a voltage-wavelength transformer and a sampler, and chirped grating FPIs, as an encoder array, can be used to obtain much greater sampling rate and bit-resolution.
基金Dr Start-up Fund of Wuyi University,National Natural Science Foundation of China(60677004)
文摘Numerically analyzed is the transmission performance of the optical millimeter (mm)-wave generated by frequency up-conversion via a phase modulator along the dispersive fiber. 60 GHz ram-wave subcarrier(SC) signals can be obtained after fiber transmission, simultaneously, the phase-modulated signals can be converted to the intensity-modulated ones. The numerical results show that the optical ram-wave at fading loops has better performance, and the eye diagram still keeps open when optical mm-wave signal is transmitted over 98 km.
文摘Converters with pulse width modulation are used for connections between the direct current (DC) and alternating current (AC) networks, e.g., in uninterrupted power supply systems, AC electromotor drives, for powering induction furnaces, in audio technique. Spectrum of signals sampled by pulse amplitude modulation and output voltage spectrum of the converter with pulse width modulation have similar properties. Spectrum of signals sampled by pulse amplitude modulation contains a harmonic of frequency equal to the frequency of the modulating signal and the harmonics of frequencies equal to the sum of frequency of the modulating signal and multiples of the sampling frequency. The output voltage spectrum of the converter with bipolar pulse width modulation contains harmonic of frequency equal to the frequency of the modulating signal and harmonics of frequencies equal to sum of the frequency of the modulating signal and multiples of the frequency of the carrier signal. It also contains harmonics of frequencies equal to the sum of the multiples of the frequency of the modulating signal and the multiples of the carrier signal. The comparison analysis was carried out for the harmonics of the output voltage of the converter with bipolar pulse width modulation in time domain. The dependency of the amplitudes and frequency spectrum on the wave forms of the carrier signal and modulating signal was shown. Similarity of the output voltage spectrum of the converter and signal spectrum sampled by the pulse width modulation was also shown. Key words: Output voltage converter with bipolar pulse width modulation, spectral analysis, Fourier series, carrier signal, reference signal.
文摘The electron paramagnetic resonance (EPR) parameters (zero-Geld splitting Dand g factors g_‖, g_⊥) of Cr~(4+) ions in Ca_2 GeO_4 crystals have been calculated from thecomplete high-order perturbation formulas of EPR parameters for a 3d~2 ion in trigonal MX_4clusters. In these formulas, in addition to the contributions to EPR parameters from the widely usedcrystal-field (CF) mechanism, the contributions from the charge-transfer (CT) mechanism (which areoften neglected) are included. From the calculations, it is found that for the high valence state3d~n ions in crystals, the reasonable explanation of EPR parameters (in particular, the g factors)should take both the CF and CT mechanisms into account.
文摘This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD (adjustable speed drive). A conventional ASD with 2-level PWM (pulse width modulation) inverters generate high dv/dt and high frequency common mode voltages which are harmful for the drive applications. It reduces the motor bearings life and conducted EMI (electro magnetic interference) deteriorates the insulation. In this paper, a diode clamped multilevel (3-level) inverter is used to perform dual task. It generates HF (high frequency) current to be injected at the input of the three-phase front-end rectifier thereby improving the harmonic spectra and the power factor. It also drives the induction motor. The salient feature of this paper is that it does not require separate converters for improving power factor and to drive induction motor. Furthermore, inverter switches operate with ZVS (zero voltage switching), thus reducing the switching losses substantially, The voltage stress of the switches also has been reduced to half of the conventional 2-level converter. The inverter is operated with SPWM (sinusoidal pulse width modulation) technique. The simulation results for a prototype of 2.2 kW are presented.
文摘This paper introduces a high-revolution,200kHz signal bandwidth EA modulator for low-IF GSM receivers that adopts a 2-1 cascaded single-bit structure to achieve high linearity and stability. Our design is realized in a standard 0.18μm CMOS process with art active area of 0.5mm× 1.1mm.The EA modulator is driven by a single 19.2MHz clock signal and dissipates 5.88mW from 3V power supply. The experimental results show that,with an oversampling ratio of 48, the modulator achieves a 84.4dB dynamic range,73.8dB peak SNDR, and 80dB peak SNR in the signal bandwidth of 200kHz.
基金State Key Laboratory of Natural and Biomimetic Drugs and Peking University(bmu2009137-121)
文摘For the main purpose of manipulating the functions of molecules, researchers have made great achievements on photoresponsive molecules using light as a trigger. Light has become a promising scientific tool due to it being a clean and noninvasive external stimulant. By attachment of photoresponsive moieties to molecules, the biological activities of molecules can be attenuated by light activation. With wide applications of laser in life sciences, it will be possible to achieve high spatiotemporal resolution. In this review, we focus on photoresponsive nucleic acids for photomodulating gene expression with light activation. With incorporation of photoswitchable or photocleavable moieties, biological behaviors of nucleic acids are photoregulated reversibly or irreversibly. Recent development and applications of photoresponsive nucleic acid in vitro and in vivo have shown a very promising future for manipulation of specific functional genes or disease genes. We expect that photoresponsive nucleic acids will be powerful scientific tools for studying biological events as well as gene therapy agents for genetic diseases.
基金supported by the Model Animal Research Center of Nanjing University Start Fundthe Jiangsu Natural Science Foundation(BK20140600)
文摘Skeletal muscle fitness plays vital roles in human health and disease and is determined by developmental as well as physiological inputs. These inputs control and coordinate muscle fiber programs, including capacity for fuel burning, mitochondrial ATP production, and contraction. Recent studies have demonstrated crucial roles for nuclear receptors and their co-activators, and micro RNAs(mi RNAs) in the regulation of skeletal muscle energy metabolism and fiber type determination. In this review, we present recent progress in the study of nuclear receptor signaling and mi RNA networks in muscle fiber type switching. We also discuss the therapeutic potential of nuclear receptors and mi RNAs in disease states that are associated with loss of muscle fitness.
文摘We investigate the thermoelectric energy conversion efficiency of Si and Ge nanowires, and in particular, that of Si/Ge core-shell nanowires. We show how the presence of a thin Ge shell on a Si core nanowire increases the overall figure of merit. We find the optimal thickness of the Ge shell to provide the largest figure of merit for the devices. We also consider Ge core/Si shell nanowires, and show that an optimal thickness of the Si shell does not exist, since the figure of merit is a monotonically decreasing function of the radius of the nanowire. Finally, we verify the empirical law relating the electron energy gap to the optimal working temperature that maximizes the efficiency of the device.