Ammonium level in body fluids serves as one of the critical biomarkers for healthcare,especially those relative to liver diseases.The continuous and real-time monitoring in both invasive and noninvasive manners is hig...Ammonium level in body fluids serves as one of the critical biomarkers for healthcare,especially those relative to liver diseases.The continuous and real-time monitoring in both invasive and noninvasive manners is highly desired,while the ammonium concentrations vary largely in different body fluids.Besides,the sensing reliability based on ion-selective biosensors can be significantly interfered by potassium ions.To tackle these challenges,a flexible and biocompatible sensing patch for wireless ammonium level sensing was reported with an ultrawide linear range for universal body fluids including blood,tears,saliva,sweat and urine.The as-prepared biocompatible sensors deliver a reliable sensitivity of 58.7 mV decade-1 in the range of 1-100 mM and a desirable selectivity coefficient of 0.11 in the interference of potassium ions,attributed to the cross-calibration within the sensors array.The sensor’s biocompatibility was validated by the cell growth on the sensor surface(>80%),hemolysis rates(<5%),negligible cellular inflammatory responses and weight changes of the mice with implanted sensors.Such biocompatible sensors with ultrawide linear range and desirable selectivity open up new possibility of highly compatible biomarker analysis via different body fluids in versatile approaches.展开更多
With reference to the air target detection of ultra-wide band (UWB)/impulse radar(IR), the transient signal processing techniques was discussed. In weak UWB signal detection, the wavelet transforms and high order spec...With reference to the air target detection of ultra-wide band (UWB)/impulse radar(IR), the transient signal processing techniques was discussed. In weak UWB signal detection, the wavelet transforms and high order spectrum estimation techniques were preferred. In target characteristic analysis, a time domain bispectrum estimation algorithm was used to analyze the target impulse response, which could estimate accurately local scattering distribution of complex target. A free field IR experimental system installed in an anechoic chamber was used. With this system, experiments to several target models were made. The results of these experiments verified the signal processing method efficiency.展开更多
One judiciously designed strategy of utilizing an ultrathin but conductive Ga_(2)O_(3):Si nanolayer to prepare(AlGa)_(2)O_(3)crystalline film is demonstrated.Benefiting from the existence of Ga_(2)O_(3):Si nanolayer,a...One judiciously designed strategy of utilizing an ultrathin but conductive Ga_(2)O_(3):Si nanolayer to prepare(AlGa)_(2)O_(3)crystalline film is demonstrated.Benefiting from the existence of Ga_(2)O_(3):Si nanolayer,a high-quality(Al_(0.68)Ga_(0.32))_(2)O_(3)sesquioxide film with 68 at.%aluminum was epitaxially grown on sapphire substrates,which was characterized by high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy and X-ray diffraction.Its bandgap was broadened to 6.14 eV,and a vacuum ultraviolet(VUV)(AlGa)_(2)O_(3)/Ga_(2)O_(3):Si photodetector was subsequently fabricated.The detector exhibits a pretty high on-off ratio of about 10^(3),an open-circuit voltage of 1.0 V and a responsivity of 8.1 mA W^(-1) at 0 V bias voltage.The performances imply that the proposed strategy is valuable for improving the quality and also adjusting the bandgap of(AlGa)_(2)O_(3)sesquioxides,which is expected to facilitate their application in VUV photodetection.展开更多
Nonlinear optical(NLO)switchable materials have attracted intense attention because of their promising applications in optoelectronic devices.However,previous studies are mainly limited to molecular-based compounds th...Nonlinear optical(NLO)switchable materials have attracted intense attention because of their promising applications in optoelectronic devices.However,previous studies are mainly limited to molecular-based compounds that usually exhibit narrow bandgaps.Here,we report all-inorganic Li_(9)Na_(3)Rb_(2)(SO_(4))_(7) as an ultrawide-bandgap NLO switchable material.展开更多
Materials with zero-linear compressibility(ZLC)and zero-area compressibility(ZAC)have great promise for specific applications retaining constancy in specific directions or planes under external impaction.To date,no mo...Materials with zero-linear compressibility(ZLC)and zero-area compressibility(ZAC)have great promise for specific applications retaining constancy in specific directions or planes under external impaction.To date,no more than 10 ZLC/ZAC materials have been reported,most of which have very limited working pressure ranges(<10 GPa).Herein,we report the observation of ZLC and ZAC in Li2Ti(IO3)6 with a gear-spring type structure over an ultrawide pressure range(0–40 GPa).展开更多
Background:Subacute sclerosing panencephalitis(SSPE)is a potentially fatal complication of measles.The authors report a case of recurrent myoclonic jerks under investigation,whose ophthalmic examination pointed to the...Background:Subacute sclerosing panencephalitis(SSPE)is a potentially fatal complication of measles.The authors report a case of recurrent myoclonic jerks under investigation,whose ophthalmic examination pointed to the diagnosis.Case presentation:A 12-year-old boy with recurrent episodes of myoclonic jerks was found to have optic disc pallor and an irregular macular scar with pigmentation in the left eye.The retinal finding proved to be a strong diagnostic clue for SSPE.There was a history of exanthematous fever in childhood.Antibodies against measles were detected in both the cerebrospinal fluid and serum.Retinitis with intraretinal and subretinal hemorrhage in the right eye was noted 6-weeks after the initial presentation.Conclusion:The authors describe the importance of ophthalmic evaluation in cases of recurrent myoclonic jerks.Optical coherence tomographic features and ultrawide field imaging characteristics of a case of SSPE are described.展开更多
Ultrawide bandgap semiconductor,e.g.,diamond,is considered as the next generation of semiconductor.Here,a new orthorhombic carbon allotrope(P2_(1)2_(1)2_(1)-C16)with ultrawide bandgap and ultra-large hardness is ident...Ultrawide bandgap semiconductor,e.g.,diamond,is considered as the next generation of semiconductor.Here,a new orthorhombic carbon allotrope(P2_(1)2_(1)2_(1)-C16)with ultrawide bandgap and ultra-large hardness is identified.The stability of the newly designed carbon is confirmed by the energy,phonon spectrum,ab-initio molecular dynamics and elastic constants.The hardness ranges from 88 GPa to 93 GPa according to different models,which is comparable to diamond.The indirect bandgap reaches 6.23 eV,which is obviously larger than that of diamond,and makes it a promising ultra-wide bandgap semiconductor.Importantly,the experimental possibility is confirmed by comparing the simulated X-ray diffraction with experimental results,and two hypothetical transformation paths to synthesize it from graphite are proposed.展开更多
The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-perform...The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-performance MAMs,little attention was paid to their absorption frequency regulation to respond to variable input frequencies and their stability and durability to cope with complex environments.Here,a highly compressible polyimide-packaging carbon nanocoils/carbon foam(PI@CNCs/CF)fabricated by a facile vacuum impregnation method is reported to be used as a dynamically frequency-tunable and environmentally stable microwave absorber.PI@CNCs/CF exhibits good structural stability and mechanical properties,which allows precise absorption frequency tuning by simply changing its compression ratio.For the first time,the tunable effective absorption bandwidth can cover the whole test frequency band(2−18 GHz)with the broadest effective absorption bandwidth of 10.8 GHz and the minimum reflection loss of−60.5 dB.Moreover,PI@CNCs/CF possesses excellent heat insulation,infrared stealth,self-cleaning,flame retardant,and acid-alkali corrosion resistance,which endows it high reliability even under various harsh environments and repeated compression testing.The frequency-tunable mechanism is elucidated by combining experiment and simulation results,possibly guiding in designing dynamically frequency-tunable MAMs with good environmental stability in the future.展开更多
Aims:This study describes vascular abnormalities in X-linked retinoschisis(XLRS)using fundus fluorescein angiography(FFA)and ultra-widefield swept-source optical coherence tomography angiography(UWF SS-OCTA)to better ...Aims:This study describes vascular abnormalities in X-linked retinoschisis(XLRS)using fundus fluorescein angiography(FFA)and ultra-widefield swept-source optical coherence tomography angiography(UWF SS-OCTA)to better understand the disease's vascular features and impact.Methods:A retrospective cross-sectional study was conducted on 26 XLRS patients(46 eyes).A comprehensive ophthalmic examination was performed,including FFA and UWF SS-OCTA.FFA abnormalities were divided into peripheral schisis-associated and optic disc-associated types.Results:The mean age of patients was 11.3±6.5 years.Macular schisis appeared in 97.8%of eyes,peripheral schisis in 89.1%,and peripheral bullous schisis(PBS)in 67.39%.Major vascular changes identified by FFA included dendritic capillary dilation/leakage(91.3%),internal residual vessel leakage(78.3%),and capillary dropout/ischemia(71.7%).Minor changes included zonal retinal pigment epithelium(RPE)proliferation(6.5%),bridging vessels(4.4%),and capillary sheathing(4.4%).peripapillary choroidal neovascularization(PPCNV)was noted in 10.9%and situs inversus of optic disc in 13.0%of eyes.Additionally,situs in versus of optic disc and zonal RPE proliferation were novel findings.Major FFA changes correlated with broader PBS(P=0.045)(P<0.001)(P=0.003).Clock hours of PBS were significant predictors for internal residual vessel leakage(OR=0.30,P=0.03).No significant correlation was found between gene mutation type and FFA abnormalities(P=0.539).Conclusions:This study highlighted the significant prevalence(95.7%)of vascular abnormalities in XLRS and emphasized the importance of combining FFA with UWF SS-OCTA for comprehensive evaluation,enhancing the understanding of XLRS pathophysiology and aiding in targeted treatment approaches.展开更多
Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, an...Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, and high thermal and chemical stability with high visible-light transparency, Ga_2O_3 is regarded as the most promising candidate for UV detection.Furthermore, the bandgap of Ga_2O_3 is as high as 4.7–4.9 eV, directly corresponding to the solar-blind UV detection band with wavelength less than 280 nm. There is no need of doping in Ga_2O_3 to tune its bandgap, compared to AlGaN, MgZnO,etc, thereby avoiding alloy composition fluctuations and phase separation. At present, solar-blind Ga_2O_3 photodetectors based on single crystal or amorphous Ga_2O_3 are mainly focused on metal–semiconductor–metal and Schottky photodiodes.In this work, the recent achievements of Ga_2O_3 photodetectors are systematically reviewed. The characteristics and performances of different photodetector structures based on single crystal Ga_2O_3 and amorphous Ga_2O_3 thin film are analyzed and compared. Finally, the prospects of Ga_2O_3 UV photodetectors are forecast.展开更多
A modified RAKE receiver based on novel Recursive Least Squares （RLS） adaptive algorithm is proposed. The receiver uses L-fingered correlators, which are composed of RLS adaptive filters, to enhance the performance ...A modified RAKE receiver based on novel Recursive Least Squares （RLS） adaptive algorithm is proposed. The receiver uses L-fingered correlators, which are composed of RLS adaptive filters, to enhance the performance of multipath receiving. It can also track the amplitude of the received signal to form a real-time amplitude estimation which is correlated with the power of excess delay bin. The simulation results based on the IEEE UltraWide Band （UWB） channel models （CMI to CM4） show that the novel RLS algorithm can alter the attenuation estimation with the finger＇s power delay profile, and RAKE receiver with few fingers can be employed to get high performance.展开更多
The performance of UWB (ultrawide bandwidth) radio systems under an impulsive noise environment is first investigated. In the analysis, the Middleton's class A model is used as a model of the impulsive noise. At f...The performance of UWB (ultrawide bandwidth) radio systems under an impulsive noise environment is first investigated. In the analysis, the Middleton's class A model is used as a model of the impulsive noise. At first, the statistical characteristics of the inphase and quadrature components of the impulsive noise are investigated, and it is proved that unlike Gaussian noise, these components are dependent especially on the impulsive noise with small impulsive indices. The probability that the high amplitude noise is emitted in the inphase component which becomes firstly larger and then smaller for the larger quadrature component of impulsive noise is presented. Next, the performance of conventional UWB radio systems designed for the Gaussian noise under the impulsive noise is evaluated and numerical results show that the performance of the conventional UWB radio systems is much degraded by the effect of the impulsive noise. Using the dependence between the inphase and quadrature components of the impulsive noise, a novel UWB receiver designed for impulsive noise is proposed and the performance improvement achieved by the receiver is evaluated. Numerical results show that the performance of UWB radio systems is much improved by employing the proposed receiver.展开更多
The paper aims at designing of two stage cascaded ultra-wideband(UWB) low noise amplifier(LNA) by using negative image amplifier technique. The objective of this article is to show the performance improvement using ne...The paper aims at designing of two stage cascaded ultra-wideband(UWB) low noise amplifier(LNA) by using negative image amplifier technique. The objective of this article is to show the performance improvement using negative image amplifier technique and realization of negative valued lumped elements into microstrip line geometry. The innovative technique to realize the negative lumped elements are carried out by using Richard's Transformation and transmission line calculation. The AWR microwave office tool is used to obtain characteristics of UWB LNA design with hybrid microwave integrated circuit(HMIC) technology. The 2-stage cascaded LNA design using negative image amplifier technique achieves average gain of 23 dB gain and low noise Figure of less than 2 dB with return loss less than-8 dB for UWB 3-10 GHz. The Proper bias circuit is extracted using DC characteristics of transistor at biasing point 2 V, 20 mA and discussed in detail with LNA layout. The negative image matching technique is applied for both input and output matching network. This work will be useful for all low power UWB wireless receiver applications.展开更多
Ultrawide bandwidth (UWB) radio, a very promising technique carrying information in very short basic pulses, has properties that make it a viable candidate for short-range wireless communications. In this paper, sever...Ultrawide bandwidth (UWB) radio, a very promising technique carrying information in very short basic pulses, has properties that make it a viable candidate for short-range wireless communications. In this paper, several short-pulse waveforms based on Gaussian genetic monocycle as well as Gaussian pulse waveform, as candidates of basic UWB pulse waveforms, are firstly proposed and investigated. Their spectrum characteristics, bit transmission rate (BTR), and bit error rate (BER) performance in AWGN channel using time hopping spread spectrum (THSS) and pulse position modulation (PPM) are simulated and evaluated. The numerical results are compared and show that the basic pulse waveforms determine the spectrum characteristics of UWB signals and have much effect on the performance of UWB radio system. The performance of UWB radio system achieved by the proposed basic pulse waveforms is much better than that of UWB radio system realized by other used basic pulse waveforms under the uniform conditions. Also, the polarity of these short basic pulses does not affect the performance of UWB radio system.展开更多
The influence of pulse repetition frequency(PRF) on performance of wireless digital time hopping spread spectrum(THSS) ultrawide bandwidth(UWB) radio systems with PPM in dense multipath fading environments is firstly ...The influence of pulse repetition frequency(PRF) on performance of wireless digital time hopping spread spectrum(THSS) ultrawide bandwidth(UWB) radio systems with PPM in dense multipath fading environments is firstly investigated. The receiver used in this UWB system is a hybrid selection/maximal-ratio combining(H-S/MRC) diversity receiver in which L strongest multipath components out of N multipath diversity branches are selected and combined using maximal-ratio combining. The exact expressions for the bit error rate(BER) of this UWB system are firstly derived by using the virtual branch technique in term of PRF, the number of multipath components selected and combined L, and multipath spread of the channel and then this BER performance is evaluated. With the computer simulation for impulses having different pulse shapes, numerical results show that PRF, as well as pulse shape and the number of multipath diversity branches selected and combined L, has much effect on the BER performance of this UWB system in dense multipath fading environments. As PRF increases, the BER performance of this UWB system is much degraded under the conditions of fixed L and pulse shape.展开更多
The performance of UWB (Ultrawide Bandwidth) radio systems under class A impulsive noise environment is studied in this paper. First, while employing the Middleton’s class A model as a model of impulsive noise, the s...The performance of UWB (Ultrawide Bandwidth) radio systems under class A impulsive noise environment is studied in this paper. First, while employing the Middleton’s class A model as a model of impulsive noise, the statistical characteristics of in-phase and quadrature components of impulsive noise is investigated. It is proven that, unlike Gaussian noise, they are dependent especially due to the fact that impulsive indices are small. Next, using this above dependence, a novel UWB radio receiver designed for impulsive noise is proposed and the exact expression for the average BER (Bit Error Rate) of this receiver as a function of SNR (Signal to Noise Power Ratio) and threshold value is derived. Then, the optimum threshold value is discussed and the performance of UWB radio systems with the proposed receiver designed for impulsive noise and with the conventional receiver designed for Gaussian noise under impulsive noise environment is estimated. Numerical results are compared and show that the influence of impulsiveness index and threshold value on the performance of UWB radio systems is quite large and that the performance achieved by the proposed UWB radio receiver is much superior to that of the conventional UWB radio receiver under class A impulsive noise environment.展开更多
An all-optical ultrawide band （UWB） doublet pulse train signal generator is proposed and theoretically simulated by utilizing an inverse wavelength conversion base on the cross-gain modulation （XGM） effect in a se...An all-optical ultrawide band （UWB） doublet pulse train signal generator is proposed and theoretically simulated by utilizing an inverse wavelength conversion base on the cross-gain modulation （XGM） effect in a semiconductor optical amplifier （SOA） and controllable time delay in two optical delay lines （ODLs）. The proposed scheme is not only optically switchable in the polarity of pulse by switching the polarity of input pulse but also tunable in signal pulse width and radiofrequency （RF） spectrum by tuning the ODLs.展开更多
基金supported by the National Natural Science Foundation of China(62201243)Natural Science Foundation of Guangdong Province(2022A1515011928)+2 种基金Shenzhen Science and Technology Program(Grant No.RCYX20231211090432060,JSGGZD20220822095600001)Postgraduate Scientific Research Innovation Project of Hunan Province(CX20231306)the technical support from the Southern University of Science and Technology Core Research Facilities(SUSTech CRF)。
文摘Ammonium level in body fluids serves as one of the critical biomarkers for healthcare,especially those relative to liver diseases.The continuous and real-time monitoring in both invasive and noninvasive manners is highly desired,while the ammonium concentrations vary largely in different body fluids.Besides,the sensing reliability based on ion-selective biosensors can be significantly interfered by potassium ions.To tackle these challenges,a flexible and biocompatible sensing patch for wireless ammonium level sensing was reported with an ultrawide linear range for universal body fluids including blood,tears,saliva,sweat and urine.The as-prepared biocompatible sensors deliver a reliable sensitivity of 58.7 mV decade-1 in the range of 1-100 mM and a desirable selectivity coefficient of 0.11 in the interference of potassium ions,attributed to the cross-calibration within the sensors array.The sensor’s biocompatibility was validated by the cell growth on the sensor surface(>80%),hemolysis rates(<5%),negligible cellular inflammatory responses and weight changes of the mice with implanted sensors.Such biocompatible sensors with ultrawide linear range and desirable selectivity open up new possibility of highly compatible biomarker analysis via different body fluids in versatile approaches.
文摘With reference to the air target detection of ultra-wide band (UWB)/impulse radar(IR), the transient signal processing techniques was discussed. In weak UWB signal detection, the wavelet transforms and high order spectrum estimation techniques were preferred. In target characteristic analysis, a time domain bispectrum estimation algorithm was used to analyze the target impulse response, which could estimate accurately local scattering distribution of complex target. A free field IR experimental system installed in an anechoic chamber was used. With this system, experiments to several target models were made. The results of these experiments verified the signal processing method efficiency.
基金supported by the National Natural Science Foundation of China(91833301 and 61427901)Guangdong Natural Science Funds for Distinguished Young Scholars(2021B1515020105)Guangdong Basic and Applied Basic Research Foundation(2019A1515110916)。
文摘One judiciously designed strategy of utilizing an ultrathin but conductive Ga_(2)O_(3):Si nanolayer to prepare(AlGa)_(2)O_(3)crystalline film is demonstrated.Benefiting from the existence of Ga_(2)O_(3):Si nanolayer,a high-quality(Al_(0.68)Ga_(0.32))_(2)O_(3)sesquioxide film with 68 at.%aluminum was epitaxially grown on sapphire substrates,which was characterized by high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy and X-ray diffraction.Its bandgap was broadened to 6.14 eV,and a vacuum ultraviolet(VUV)(AlGa)_(2)O_(3)/Ga_(2)O_(3):Si photodetector was subsequently fabricated.The detector exhibits a pretty high on-off ratio of about 10^(3),an open-circuit voltage of 1.0 V and a responsivity of 8.1 mA W^(-1) at 0 V bias voltage.The performances imply that the proposed strategy is valuable for improving the quality and also adjusting the bandgap of(AlGa)_(2)O_(3)sesquioxides,which is expected to facilitate their application in VUV photodetection.
基金supported by the National Nature Science Foundation of China(21833010,61975207,21622101,21921001,21525104,and 51662013)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB20000000 and XDB20010200)+5 种基金the Natural Science Foundation of Fujian Province(2018H0047)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(ZDBS-LY-SLH024)the Natural Science Foundation of Guangxi Province(2018GXNSFDA281015)the National Key Research and Development Program of China(2019YFA0210400)Key Laboratory of Functional Crystals and Laser Technology,TIPC,CAS(FCLT 202003)Key Laboratory of New Processing Technology for Nonferrous Metal&Materials,Ministry of Education/Guangxi Key Laboratory of Optical and Electronic Materials and Devices(20KF-11).
文摘Nonlinear optical(NLO)switchable materials have attracted intense attention because of their promising applications in optoelectronic devices.However,previous studies are mainly limited to molecular-based compounds that usually exhibit narrow bandgaps.Here,we report all-inorganic Li_(9)Na_(3)Rb_(2)(SO_(4))_(7) as an ultrawide-bandgap NLO switchable material.
基金supported by the Major Program of the National Natural Science Foundation of China(no.22090041)the National Natural Science Foundation of China(no.52073003)the National Key R&D Program of China(no.2018YFA0305900).
文摘Materials with zero-linear compressibility(ZLC)and zero-area compressibility(ZAC)have great promise for specific applications retaining constancy in specific directions or planes under external impaction.To date,no more than 10 ZLC/ZAC materials have been reported,most of which have very limited working pressure ranges(<10 GPa).Herein,we report the observation of ZLC and ZAC in Li2Ti(IO3)6 with a gear-spring type structure over an ultrawide pressure range(0–40 GPa).
文摘Background:Subacute sclerosing panencephalitis(SSPE)is a potentially fatal complication of measles.The authors report a case of recurrent myoclonic jerks under investigation,whose ophthalmic examination pointed to the diagnosis.Case presentation:A 12-year-old boy with recurrent episodes of myoclonic jerks was found to have optic disc pallor and an irregular macular scar with pigmentation in the left eye.The retinal finding proved to be a strong diagnostic clue for SSPE.There was a history of exanthematous fever in childhood.Antibodies against measles were detected in both the cerebrospinal fluid and serum.Retinitis with intraretinal and subretinal hemorrhage in the right eye was noted 6-weeks after the initial presentation.Conclusion:The authors describe the importance of ophthalmic evaluation in cases of recurrent myoclonic jerks.Optical coherence tomographic features and ultrawide field imaging characteristics of a case of SSPE are described.
基金supported by the National Natural Science Foundation of China(No.51875269)the Startup Foundation of Jiangsu University of Science and Technology(No.202100000135).
文摘Ultrawide bandgap semiconductor,e.g.,diamond,is considered as the next generation of semiconductor.Here,a new orthorhombic carbon allotrope(P2_(1)2_(1)2_(1)-C16)with ultrawide bandgap and ultra-large hardness is identified.The stability of the newly designed carbon is confirmed by the energy,phonon spectrum,ab-initio molecular dynamics and elastic constants.The hardness ranges from 88 GPa to 93 GPa according to different models,which is comparable to diamond.The indirect bandgap reaches 6.23 eV,which is obviously larger than that of diamond,and makes it a promising ultra-wide bandgap semiconductor.Importantly,the experimental possibility is confirmed by comparing the simulated X-ray diffraction with experimental results,and two hypothetical transformation paths to synthesize it from graphite are proposed.
基金supported by the National Natural Science Foundation of China(grants 22278101,22068010,and 52365044)the Natural Science Foundation of Hainan Province(grants 120RC454 and 519QN176)the Innovation Project for Scientific and Technological Talents in Hainan Province(grant KJRC2023C08)。
文摘The threat to information security from electromagnetic pollution has sparked widespread interest in the development of microwave absorption materials(MAMs).Although considerable progress has been made in high-performance MAMs,little attention was paid to their absorption frequency regulation to respond to variable input frequencies and their stability and durability to cope with complex environments.Here,a highly compressible polyimide-packaging carbon nanocoils/carbon foam(PI@CNCs/CF)fabricated by a facile vacuum impregnation method is reported to be used as a dynamically frequency-tunable and environmentally stable microwave absorber.PI@CNCs/CF exhibits good structural stability and mechanical properties,which allows precise absorption frequency tuning by simply changing its compression ratio.For the first time,the tunable effective absorption bandwidth can cover the whole test frequency band(2−18 GHz)with the broadest effective absorption bandwidth of 10.8 GHz and the minimum reflection loss of−60.5 dB.Moreover,PI@CNCs/CF possesses excellent heat insulation,infrared stealth,self-cleaning,flame retardant,and acid-alkali corrosion resistance,which endows it high reliability even under various harsh environments and repeated compression testing.The frequency-tunable mechanism is elucidated by combining experiment and simulation results,possibly guiding in designing dynamically frequency-tunable MAMs with good environmental stability in the future.
基金supported by the Construction Project of High-Level Hospitals in Guangdong Province(303020107,303010303058)the National Natural Science Foundation of China(82271092,82401282)+1 种基金Guangdong Basic and Applied Research Foundation(2023A1515010430)Guangzhou Municipal Science and Technology Key Project(2024A03J0171).
文摘Aims:This study describes vascular abnormalities in X-linked retinoschisis(XLRS)using fundus fluorescein angiography(FFA)and ultra-widefield swept-source optical coherence tomography angiography(UWF SS-OCTA)to better understand the disease's vascular features and impact.Methods:A retrospective cross-sectional study was conducted on 26 XLRS patients(46 eyes).A comprehensive ophthalmic examination was performed,including FFA and UWF SS-OCTA.FFA abnormalities were divided into peripheral schisis-associated and optic disc-associated types.Results:The mean age of patients was 11.3±6.5 years.Macular schisis appeared in 97.8%of eyes,peripheral schisis in 89.1%,and peripheral bullous schisis(PBS)in 67.39%.Major vascular changes identified by FFA included dendritic capillary dilation/leakage(91.3%),internal residual vessel leakage(78.3%),and capillary dropout/ischemia(71.7%).Minor changes included zonal retinal pigment epithelium(RPE)proliferation(6.5%),bridging vessels(4.4%),and capillary sheathing(4.4%).peripapillary choroidal neovascularization(PPCNV)was noted in 10.9%and situs inversus of optic disc in 13.0%of eyes.Additionally,situs in versus of optic disc and zonal RPE proliferation were novel findings.Major FFA changes correlated with broader PBS(P=0.045)(P<0.001)(P=0.003).Clock hours of PBS were significant predictors for internal residual vessel leakage(OR=0.30,P=0.03).No significant correlation was found between gene mutation type and FFA abnormalities(P=0.539).Conclusions:This study highlighted the significant prevalence(95.7%)of vascular abnormalities in XLRS and emphasized the importance of combining FFA with UWF SS-OCTA for comprehensive evaluation,enhancing the understanding of XLRS pathophysiology and aiding in targeted treatment approaches.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61521064,61522408,61574169,61334007,61474136,and 61574166)the Ministry of Science and Technology of China(Grant Nos.2018YFB0406504,2016YFA0201803,2016YFA0203800,and 2017YFB0405603)+1 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(Grant Nos.QYZDB-SSW-JSC048 and QYZDY-SSW-JSC001)the Beijing Municipal Science and Technology Project,China(Grant No.Z171100002017011)
文摘Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, and high thermal and chemical stability with high visible-light transparency, Ga_2O_3 is regarded as the most promising candidate for UV detection.Furthermore, the bandgap of Ga_2O_3 is as high as 4.7–4.9 eV, directly corresponding to the solar-blind UV detection band with wavelength less than 280 nm. There is no need of doping in Ga_2O_3 to tune its bandgap, compared to AlGaN, MgZnO,etc, thereby avoiding alloy composition fluctuations and phase separation. At present, solar-blind Ga_2O_3 photodetectors based on single crystal or amorphous Ga_2O_3 are mainly focused on metal–semiconductor–metal and Schottky photodiodes.In this work, the recent achievements of Ga_2O_3 photodetectors are systematically reviewed. The characteristics and performances of different photodetector structures based on single crystal Ga_2O_3 and amorphous Ga_2O_3 thin film are analyzed and compared. Finally, the prospects of Ga_2O_3 UV photodetectors are forecast.
基金Supported by the Chinese 863 National High Technology Program (No.2002AA783043)the National Natural Science Foundation of China (No.60390540).
文摘A modified RAKE receiver based on novel Recursive Least Squares （RLS） adaptive algorithm is proposed. The receiver uses L-fingered correlators, which are composed of RLS adaptive filters, to enhance the performance of multipath receiving. It can also track the amplitude of the received signal to form a real-time amplitude estimation which is correlated with the power of excess delay bin. The simulation results based on the IEEE UltraWide Band （UWB） channel models （CMI to CM4） show that the novel RLS algorithm can alter the attenuation estimation with the finger＇s power delay profile, and RAKE receiver with few fingers can be employed to get high performance.
文摘The performance of UWB (ultrawide bandwidth) radio systems under an impulsive noise environment is first investigated. In the analysis, the Middleton's class A model is used as a model of the impulsive noise. At first, the statistical characteristics of the inphase and quadrature components of the impulsive noise are investigated, and it is proved that unlike Gaussian noise, these components are dependent especially on the impulsive noise with small impulsive indices. The probability that the high amplitude noise is emitted in the inphase component which becomes firstly larger and then smaller for the larger quadrature component of impulsive noise is presented. Next, the performance of conventional UWB radio systems designed for the Gaussian noise under the impulsive noise is evaluated and numerical results show that the performance of the conventional UWB radio systems is much degraded by the effect of the impulsive noise. Using the dependence between the inphase and quadrature components of the impulsive noise, a novel UWB receiver designed for impulsive noise is proposed and the performance improvement achieved by the receiver is evaluated. Numerical results show that the performance of UWB radio systems is much improved by employing the proposed receiver.
文摘The paper aims at designing of two stage cascaded ultra-wideband(UWB) low noise amplifier(LNA) by using negative image amplifier technique. The objective of this article is to show the performance improvement using negative image amplifier technique and realization of negative valued lumped elements into microstrip line geometry. The innovative technique to realize the negative lumped elements are carried out by using Richard's Transformation and transmission line calculation. The AWR microwave office tool is used to obtain characteristics of UWB LNA design with hybrid microwave integrated circuit(HMIC) technology. The 2-stage cascaded LNA design using negative image amplifier technique achieves average gain of 23 dB gain and low noise Figure of less than 2 dB with return loss less than-8 dB for UWB 3-10 GHz. The Proper bias circuit is extracted using DC characteristics of transistor at biasing point 2 V, 20 mA and discussed in detail with LNA layout. The negative image matching technique is applied for both input and output matching network. This work will be useful for all low power UWB wireless receiver applications.
文摘Ultrawide bandwidth (UWB) radio, a very promising technique carrying information in very short basic pulses, has properties that make it a viable candidate for short-range wireless communications. In this paper, several short-pulse waveforms based on Gaussian genetic monocycle as well as Gaussian pulse waveform, as candidates of basic UWB pulse waveforms, are firstly proposed and investigated. Their spectrum characteristics, bit transmission rate (BTR), and bit error rate (BER) performance in AWGN channel using time hopping spread spectrum (THSS) and pulse position modulation (PPM) are simulated and evaluated. The numerical results are compared and show that the basic pulse waveforms determine the spectrum characteristics of UWB signals and have much effect on the performance of UWB radio system. The performance of UWB radio system achieved by the proposed basic pulse waveforms is much better than that of UWB radio system realized by other used basic pulse waveforms under the uniform conditions. Also, the polarity of these short basic pulses does not affect the performance of UWB radio system.
文摘The influence of pulse repetition frequency(PRF) on performance of wireless digital time hopping spread spectrum(THSS) ultrawide bandwidth(UWB) radio systems with PPM in dense multipath fading environments is firstly investigated. The receiver used in this UWB system is a hybrid selection/maximal-ratio combining(H-S/MRC) diversity receiver in which L strongest multipath components out of N multipath diversity branches are selected and combined using maximal-ratio combining. The exact expressions for the bit error rate(BER) of this UWB system are firstly derived by using the virtual branch technique in term of PRF, the number of multipath components selected and combined L, and multipath spread of the channel and then this BER performance is evaluated. With the computer simulation for impulses having different pulse shapes, numerical results show that PRF, as well as pulse shape and the number of multipath diversity branches selected and combined L, has much effect on the BER performance of this UWB system in dense multipath fading environments. As PRF increases, the BER performance of this UWB system is much degraded under the conditions of fixed L and pulse shape.
文摘The performance of UWB (Ultrawide Bandwidth) radio systems under class A impulsive noise environment is studied in this paper. First, while employing the Middleton’s class A model as a model of impulsive noise, the statistical characteristics of in-phase and quadrature components of impulsive noise is investigated. It is proven that, unlike Gaussian noise, they are dependent especially due to the fact that impulsive indices are small. Next, using this above dependence, a novel UWB radio receiver designed for impulsive noise is proposed and the exact expression for the average BER (Bit Error Rate) of this receiver as a function of SNR (Signal to Noise Power Ratio) and threshold value is derived. Then, the optimum threshold value is discussed and the performance of UWB radio systems with the proposed receiver designed for impulsive noise and with the conventional receiver designed for Gaussian noise under impulsive noise environment is estimated. Numerical results are compared and show that the influence of impulsiveness index and threshold value on the performance of UWB radio systems is quite large and that the performance achieved by the proposed UWB radio receiver is much superior to that of the conventional UWB radio receiver under class A impulsive noise environment.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61501088, 61307088, 61505020, and 61675040）, the Joint Funds of the National Natural Science Foundation of China （Grant No. U1633129）, the Science and Technology Planning Project of Sichuan Province （No. MZ2016036）, and the Fundamental Research Funds for the Central Universities （Nos. ZYGX2016J003, ZYGX2016J005, and ZYGX2016J009）.
文摘An all-optical ultrawide band （UWB） doublet pulse train signal generator is proposed and theoretically simulated by utilizing an inverse wavelength conversion base on the cross-gain modulation （XGM） effect in a semiconductor optical amplifier （SOA） and controllable time delay in two optical delay lines （ODLs）. The proposed scheme is not only optically switchable in the polarity of pulse by switching the polarity of input pulse but also tunable in signal pulse width and radiofrequency （RF） spectrum by tuning the ODLs.
