Secret key generation(SKG)is a promising solution to the problem of wireless communications security.As the first step of SKG,channel probing affects it significantly.Although there have been some probing schemes,ther...Secret key generation(SKG)is a promising solution to the problem of wireless communications security.As the first step of SKG,channel probing affects it significantly.Although there have been some probing schemes,there is a lack of research on the optimization of the probing process.This study investigates how to optimize correlated parameters to maximize the SKG rate(SKGR)in the time-division duplex(TDD)mode.First,we build a probing model which includes the effects of transmitting power,the probing period,and the dimension of sample vectors.Based on the model,the analytical expression of the SKGR is given.Next,we formulate an optimization problem for maximizing the SKGR and give an algorithm to solve it.We conclude the SKGR monotonically increases as the transmitting power increases.Relevant mathematical proofs are given in this study.From the simulation results,increasing appropriately the probing period and the dimension of the sample vector could increase the SKGR dramatically compared to a yardstick,which indicates the importance of optimizing the parameters related to the channel probing phase.展开更多
The membrane method based on adaptive wettability shows great advantages in oil-water separation.At present,researches focus on the excellent application performance of the membrane material,while the quantitative ana...The membrane method based on adaptive wettability shows great advantages in oil-water separation.At present,researches focus on the excellent application performance of the membrane material,while the quantitative analysis of interactions in oil-water separation is rarely recognized.Herein,we constructed an adaptable wettability membrane with multiple polymer networks by polydopamine(PDA)and mussel-inspired amphiphilic polymer.Based on the Owens three-probe liquid method,the surface energy of the modified membrane was verified to meet the adaptive wettability conditions,with surface energies(γ-8)of 147.6 mJ m^(−2)(superhydrophilic/underwater superoleophobic)and 49.87 mJ m^(−2)(superhydrophobic/superoleophobic),respectively.The adhesion or repulsion of the membrane to the oil phase under different conditions during the separation process was quantified by the chemical probe AFM technique.In addition,the oil-water selective separation mechanism was further analyzed in a simplified membrane microchannel model.The results show that the different wetting produces capillary additional pressure in opposite directions,resulting in different energies to be overcome when the oil or water passes through the microchannels,thus achieving selective separation.展开更多
AIM:To investigate the clinical outcomes of different intubation techniques in the cases of failed primary probing.METHODS: This retrospective study was performed on338 patients with the diagnosis of congenital naso...AIM:To investigate the clinical outcomes of different intubation techniques in the cases of failed primary probing.METHODS: This retrospective study was performed on338 patients with the diagnosis of congenital nasolacrimal duct obstruction with age 1-4y that had failed primary probing.Intubation was performed under light sedation in operating room and the stent was left 3mo in place.Clinical outcome was investigated 3mo after tube removal.RESULTS: Bicanalicular intubation method had higher complete and relative success rates compared to monocanalicular intubation(P =0.00).In addition,Monoka intubation had better outcomes compared to Masterka technique(P =0.046).No difference was found between genders but the higher the age,the better the outcomes with bicanalicular technique rather than monocanalicular.CONCLUSION: Overall success rate of bicanalicular intubation is superior to monocanalicular technique especially in older ages.Also,based upon our clinical outcomes,Masterka intubation is not recommended in cases of failed probing.展开更多
The second IGCP-649 Workshop, held in Agros-Cyprus during 14-20 May 2016, brought together nearly fifty international scientists from around the world, and included a 5-day field excursion on the classic Troodos ophio...The second IGCP-649 Workshop, held in Agros-Cyprus during 14-20 May 2016, brought together nearly fifty international scientists from around the world, and included a 5-day field excursion on the classic Troodos ophiolite. Organized by the IGCP-649 Project Leadership and the Geological Survey Department of Cyprus, the workshop provided a forum for discussions on the latest views and interpretations on the petrogenesis of crustal and upper mantle peridotites in ophiolites, and introduced many young researchers and students to the intemal structure of the classical Troodos ophiolite. This was particularly the case for a large group of Chinese scholars and students, who visited Cyprus and the Troodos ophiolite for the first time. A 4-day profile across the complete ophiolite sequence gave these scientists a first- hand opportunity to examine the lithological and compositional variations within the Cretaceous oceanic crust and to study the igneous and tectonic contacts between them. Lively discussions by the experts and students in front of some of the best 3-dimensional outcrops were most fruitful and allowed all participants to compare the Troodos tectonics with some of ophiolites elsewhere. structure, geochemistry and the other well-documented展开更多
Ultrafast dissociation dynamics of chloroiodomethane (CH2ICl) in the B band is studied by femtosecond time- resolved time-of-flight (TOF) mass spectrometry. Time-resolved TOF mass signal of parent ion (CH2ICl+)...Ultrafast dissociation dynamics of chloroiodomethane (CH2ICl) in the B band is studied by femtosecond time- resolved time-of-flight (TOF) mass spectrometry. Time-resolved TOF mass signal of parent ion (CH2ICl+) and main daughter ion (CH2Cl+) are obtained. The curve for the transient signal of CH2ICl+ is simple and can be well fitted by an exponential decay convoluted with a Gaussian function. The decay constant determined to be less than 35 fs reflects the lifetime of the B band. Significant substituent effects on photodissociation dynamics of CH2IC1 compared with CH3I are discussed. The dissociation time from the parent ion CH2IC1+ to the daughter ion CH2Cl+ is determined in the experiment. The optimized geometry of the ionic state of CH2ICl and the ionization energy are calculated for further analysis of the measurements. In addition, compared with the parent ion, a new decay component with time constant of -596 fs is observed for CH2Cl+, and reasonable mechanisms are proposed for the explanation.展开更多
To evaluate the ^(125)I radioactive probing re-canalizing stenostic nasolacrimal duct,the nasolacrimal duct stenosis models in epithelium and connective tissues are experimentally structured by inbred white rabbits(Ne...To evaluate the ^(125)I radioactive probing re-canalizing stenostic nasolacrimal duct,the nasolacrimal duct stenosis models in epithelium and connective tissues are experimentally structured by inbred white rabbits(New Zealand),including the nasolacrimal duct stenosis,the mechanical probing with outer layer of thermoplastic tube,and the ^(125)I radioactive probing with the ^(125)I seeds sealing into the thermoplastic tube.After re-canalized for four weeks, tissue specimens from bilateral nasolacrimal ducts are obtained,and the Bcl-2 and Bax protein expression levels are evaluated by immunohistochemical staining analysis.Comparing with the blank control,the expression levels of the Bcl-2 and Bax in the nasolacrimal duct stenosis and the mechanical probing are significantly up-/down-regulated(p<0.05),but in the ^(125)I radioactive probing are down-/up-regulated(p<0.05) and can be used to re-canalize the stenostic lacrimal passage.The results show that the ^(125)I radioactive probing is a therapeutical mechanism for radioactive probing strategy for treating nasolacrimal duct stenosis to induce cell apoptosis.展开更多
We report the direct imaging of plasmon on the tips pulses and probing of ultrafast plasmon dynamics by of nano-prisms in a bowtie structure excited by 7 fs laser combining the pump-probe technology with three-photon ...We report the direct imaging of plasmon on the tips pulses and probing of ultrafast plasmon dynamics by of nano-prisms in a bowtie structure excited by 7 fs laser combining the pump-probe technology with three-photon photoemission electron microscopy. Different photoemission patterns induced by the plasmon effect are observed when the bowties are excited by s- and p-polarized femtosecond laser pulses. A series of images of the evolution of local surface plasmon modes on different tips of the bowtie are obtained by the time-resolved three-photon photoemission electron microscopy, and the result discloses that plasmon excitation is dominated by the interfer- ence of the pump and probe pulses within the first 13 fs of the delay time, and thereafter the individual plasmon starts to oscillate on its own characteristic resonant frequencies.展开更多
Spatial distribution of acoustic and elastic waves generated by an elementary vibration source at seismic profiling frequencies in an infinite medium close to a layer inclusion, i.e., an extended layer, is numerically...Spatial distribution of acoustic and elastic waves generated by an elementary vibration source at seismic profiling frequencies in an infinite medium close to a layer inclusion, i.e., an extended layer, is numerically simulated. Point dipole radiation in a homogeneous infinite medium separated by a liquid layer of different medium density or acoustic wave velocity is considered. Transverse elastic SH-waves excited by an oscillating power source in a solid medium also located close to the layer of different propagation velocity than the velocity of the vicinity are analyzed. Formulae for the spatial distribution of the wave field amplitude are derived and computer graphics of field distribution images is presented. Wave reflection, penetration deep into the layer inclusion, and transmittance through it are examined. Results of the analysis can be applied to seismoacoustic probing of geologic environment by the near field of a harmonic vibration source.展开更多
A fully automatic setup for on-wafer contact probing will be presented. This setup consists of six automatable nano positioning axes used as tool holder and a sample holder. With this setup a fully automatic one-port ...A fully automatic setup for on-wafer contact probing will be presented. This setup consists of six automatable nano positioning axes used as tool holder and a sample holder. With this setup a fully automatic one-port SOL calibration for a Vector Network Analyzer is done. Furthermore a fully automated on-wafer contact probing is performed. Afterwards, the effects of a misalignment of the three tips of a GSG-probe are examined. Additionally the error on the calibration is calculated to determine its effect on the measurement. The results show, that a misalignment of the probe has a high impact on the measurement of the VNA. Hence a fully automated on-wafer probing presented in this paper is a good way to detect these misalignments and correct them if necessary.展开更多
To satisfy the measuring demands for the micro components of the industry, micro/nano probing systems with various ball tips have been developed. However, most of them cannot be used to measure the real micro geometri...To satisfy the measuring demands for the micro components of the industry, micro/nano probing systems with various ball tips have been developed. However, most of them cannot be used to measure the real micro geometrical features high precisely because the parameters of the ball tips are not appropriate. The ball tips with a diameter of less than 100 μm, a sphericity and eccentricity of far less than 1 μm are required urgently. A review on the state-of-the-art of ball tips of micro/nano probing systems is presented. The material characteristics and geometric parameters of now available ball tips are introduced sepa- rately. The existing fabrication methods for the ball tips are demonstrated and summarized. The ball tips' future trends, which are smaller diameter, better sphericity and smaller eccentricity, are proposed in view of the practical requirements of high-precision measurement for micro geometrical features. Some challenges have to be faced in future, such as the promotion and high-precision measurement for the small ball tip's sphericity and eccentricity. Fusion method without the gravity effect when the molten ball tip solidifying is a more suitable way to fabricate a small diameter ball tip together with a shaft.展开更多
The accessibility of coordinate measuring machines (CMMs) in dimensional inspection is studied. The problem of computing the global accessibility cone is solved using a method of angle representation. Otherwise, the l...The accessibility of coordinate measuring machines (CMMs) in dimensional inspection is studied. The problem of computing the global accessibility cone is solved using a method of angle representation. Otherwise, the length and volume of probe are considered sufficiently so that all the feasible probe orientations could be determined for the inspection of a workpiece when a touch trigger probe is used and the shortcoming of abstracting a probe as an infinite half line could be overcome completely. In the end, an example is given to explain the method.展开更多
Mitochondrial damage is closely related to the occurrence of many diseases.However,accurate monitoring and reporting of mitochondrial damage are not easy.Here,we developed a small molecule fluorescent probe named CB-C...Mitochondrial damage is closely related to the occurrence of many diseases.However,accurate monitoring and reporting of mitochondrial damage are not easy.Here,we developed a small molecule fluorescent probe named CB-Cl,which has splendid spectral properties(large Stokes shift,strong affinity for RNA,etc.)and excellent targeting ability to intracellular mitochondria.After mitochondria were damaged by external stimuli,CB-Cl would light up the nucleolus as a signal reporter.The cascade imaging of mitochondria and nucleolus using CB-Cl can monitor and visualize the mitochondrial status in living cells in real-time.Based on the above advantages,the probe CB-Cl has reference significance for the related research of mitochondrial damage and the prevention and treatment of related diseases.展开更多
Imaging biomolecules in real space is crucial for gaining a comprehensive understanding of the properties and functions of biological systems at the most fundamental level.Among the various imaging techniques availabl...Imaging biomolecules in real space is crucial for gaining a comprehensive understanding of the properties and functions of biological systems at the most fundamental level.Among the various imaging techniques available for biomolecules and their assembled nanostructures,scanning probe microscopy(SPM)provides a powerful and nondestructive imaging option.SPM is unique in visualizing intrinsically disordered biomolecules at the nanometer scale(e.g.,glycans).This review highlights recent achievements in studying biomolecules using SPM technique,focusing on DNA bases,amino acids,proteins,and glycans.The atomic-level analysis of biomolecules made possible by SPM allows for a more accurate definition of the local structure–property relationship.High-resolution SPM imaging of single biomolecules offers a new way to study basic processes of life at the molecular level.展开更多
Cell membrane integrity is fundamental to the normal activities of cells and is involved in both acute and chronic pathologies.Here,we report a probe for analyzing cell membrane integrity developed from a 9 nm-sized p...Cell membrane integrity is fundamental to the normal activities of cells and is involved in both acute and chronic pathologies.Here,we report a probe for analyzing cell membrane integrity developed from a 9 nm-sized protein nanocage named Dps via fluorophore conjugation with high spatial precision to avoid self-quenching.The probe cannot enter normal live cells but can accumulate in dead or live cells with damaged membranes,which,interestingly,leads to weak cytoplasmic and strong nuclear staining.This differential staining is found attributed to the high affinity of Dps for histones rather than DNA,providing a staining mechanism different from those of known membrane exclusion probes(MEPs).Moreover,the Dps nanoprobe is larger in size and thus applies a more stringent criterion for identifying severe membrane damage than currently available MEPs.This study shows the potential of Dps as a new bioimaging platform for biological and medical analyses.展开更多
Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of ...Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses,making this technique advantageous over macroscopic approaches.Despite its widespread application in ferroelectrics,it has rarely been used to investigate the ferrielectric(FiE)behaviors in antiferroelectric(AFE)materials.Herein,the PFM was utilized to study the local electromechanical behavior and distribution of FiE,and the AFE phases of PbZrO_(3)thin-film were studied,where only the FiE behavior is observable using a macroscopic approach.The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages.In contrast,the AFE region only yields an observable response at high voltages.Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations.Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior,thereby providing insights to guide property modification and potential applications.展开更多
Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-s...Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.展开更多
Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge s...Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with ^13C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant 13C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U(VI) reduction in the less reduced sample. I3C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron (Ⅲ) reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillus and others, including the known U(VI)-redueing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobac- ter and Desulfosporosinus. The findings suggest that ethanol biostimulates the U(VI)-reducing microbial com- munity by first serving as an electron donor for nitrate, sulfate, iron (IH) and U(VI) reduction, and acetate which then functions as electron donor for U(VI) reduction and carbon source for microbial growth.展开更多
RNA folds into intricate structures that are crucial for its functions and regulations. To date, a multitude of approaches for probing structures of the whole transcriptome, i.e., RNA struc- turomes, have been develop...RNA folds into intricate structures that are crucial for its functions and regulations. To date, a multitude of approaches for probing structures of the whole transcriptome, i.e., RNA struc- turomes, have been developed. Applications of these approaches to different cell lines and tissues have generated a rich resource for the study of RNA structure-function relationships at a systems biology level. In this review, we first introduce the designs of these methods and their applications to study different RNA structuromes. We emphasize their technological differences especially their unique advantages and caveats. We then summarize the structural insights in RNA functions and regulations obtained from the studies of RNA structuromes. And finally, we propose potential directions for future improvements and studies.展开更多
基金supported in part by the national natural science foundation of China (NSFC) under Grant61871193in part by the R&D Program of key science and technology fields in Guangdong province under Grant 2019B090912001in part by the Guangzhou Key Field R&D Program under Grant 202206030005
文摘Secret key generation(SKG)is a promising solution to the problem of wireless communications security.As the first step of SKG,channel probing affects it significantly.Although there have been some probing schemes,there is a lack of research on the optimization of the probing process.This study investigates how to optimize correlated parameters to maximize the SKG rate(SKGR)in the time-division duplex(TDD)mode.First,we build a probing model which includes the effects of transmitting power,the probing period,and the dimension of sample vectors.Based on the model,the analytical expression of the SKGR is given.Next,we formulate an optimization problem for maximizing the SKGR and give an algorithm to solve it.We conclude the SKGR monotonically increases as the transmitting power increases.Relevant mathematical proofs are given in this study.From the simulation results,increasing appropriately the probing period and the dimension of the sample vector could increase the SKGR dramatically compared to a yardstick,which indicates the importance of optimizing the parameters related to the channel probing phase.
基金We gratefully acknowledge the financial support from National Key Research and Development Project,China(2019YFA0708700)the National Natural Science Foundation of China(52222403,52074333)the Innovation Fund Project for graduate students of China University of Petroleum(East China)(22CX04049A).
文摘The membrane method based on adaptive wettability shows great advantages in oil-water separation.At present,researches focus on the excellent application performance of the membrane material,while the quantitative analysis of interactions in oil-water separation is rarely recognized.Herein,we constructed an adaptable wettability membrane with multiple polymer networks by polydopamine(PDA)and mussel-inspired amphiphilic polymer.Based on the Owens three-probe liquid method,the surface energy of the modified membrane was verified to meet the adaptive wettability conditions,with surface energies(γ-8)of 147.6 mJ m^(−2)(superhydrophilic/underwater superoleophobic)and 49.87 mJ m^(−2)(superhydrophobic/superoleophobic),respectively.The adhesion or repulsion of the membrane to the oil phase under different conditions during the separation process was quantified by the chemical probe AFM technique.In addition,the oil-water selective separation mechanism was further analyzed in a simplified membrane microchannel model.The results show that the different wetting produces capillary additional pressure in opposite directions,resulting in different energies to be overcome when the oil or water passes through the microchannels,thus achieving selective separation.
文摘AIM:To investigate the clinical outcomes of different intubation techniques in the cases of failed primary probing.METHODS: This retrospective study was performed on338 patients with the diagnosis of congenital nasolacrimal duct obstruction with age 1-4y that had failed primary probing.Intubation was performed under light sedation in operating room and the stent was left 3mo in place.Clinical outcome was investigated 3mo after tube removal.RESULTS: Bicanalicular intubation method had higher complete and relative success rates compared to monocanalicular intubation(P =0.00).In addition,Monoka intubation had better outcomes compared to Masterka technique(P =0.046).No difference was found between genders but the higher the age,the better the outcomes with bicanalicular technique rather than monocanalicular.CONCLUSION: Overall success rate of bicanalicular intubation is superior to monocanalicular technique especially in older ages.Also,based upon our clinical outcomes,Masterka intubation is not recommended in cases of failed probing.
文摘The second IGCP-649 Workshop, held in Agros-Cyprus during 14-20 May 2016, brought together nearly fifty international scientists from around the world, and included a 5-day field excursion on the classic Troodos ophiolite. Organized by the IGCP-649 Project Leadership and the Geological Survey Department of Cyprus, the workshop provided a forum for discussions on the latest views and interpretations on the petrogenesis of crustal and upper mantle peridotites in ophiolites, and introduced many young researchers and students to the intemal structure of the classical Troodos ophiolite. This was particularly the case for a large group of Chinese scholars and students, who visited Cyprus and the Troodos ophiolite for the first time. A 4-day profile across the complete ophiolite sequence gave these scientists a first- hand opportunity to examine the lithological and compositional variations within the Cretaceous oceanic crust and to study the igneous and tectonic contacts between them. Lively discussions by the experts and students in front of some of the best 3-dimensional outcrops were most fruitful and allowed all participants to compare the Troodos tectonics with some of ophiolites elsewhere. structure, geochemistry and the other well-documented
基金Supported by the National Natural Science Foundation of China under Grant Nos 11304157,21303255 and 11475229the‘Six Talent Peaks’Project in Jiangsu Province under Grant No 2015-JNHB-011the College Students Practice Innovative Training Program of Nuist under Grant No 201610300042
文摘Ultrafast dissociation dynamics of chloroiodomethane (CH2ICl) in the B band is studied by femtosecond time- resolved time-of-flight (TOF) mass spectrometry. Time-resolved TOF mass signal of parent ion (CH2ICl+) and main daughter ion (CH2Cl+) are obtained. The curve for the transient signal of CH2ICl+ is simple and can be well fitted by an exponential decay convoluted with a Gaussian function. The decay constant determined to be less than 35 fs reflects the lifetime of the B band. Significant substituent effects on photodissociation dynamics of CH2IC1 compared with CH3I are discussed. The dissociation time from the parent ion CH2IC1+ to the daughter ion CH2Cl+ is determined in the experiment. The optimized geometry of the ionic state of CH2ICl and the ionization energy are calculated for further analysis of the measurements. In addition, compared with the parent ion, a new decay component with time constant of -596 fs is observed for CH2Cl+, and reasonable mechanisms are proposed for the explanation.
基金Supported by Natural Science Foundation of Jilin Province(No.200705327)Project of Science and Technology of Changchun City(2007GH25)
文摘To evaluate the ^(125)I radioactive probing re-canalizing stenostic nasolacrimal duct,the nasolacrimal duct stenosis models in epithelium and connective tissues are experimentally structured by inbred white rabbits(New Zealand),including the nasolacrimal duct stenosis,the mechanical probing with outer layer of thermoplastic tube,and the ^(125)I radioactive probing with the ^(125)I seeds sealing into the thermoplastic tube.After re-canalized for four weeks, tissue specimens from bilateral nasolacrimal ducts are obtained,and the Bcl-2 and Bax protein expression levels are evaluated by immunohistochemical staining analysis.Comparing with the blank control,the expression levels of the Bcl-2 and Bax in the nasolacrimal duct stenosis and the mechanical probing are significantly up-/down-regulated(p<0.05),but in the ^(125)I radioactive probing are down-/up-regulated(p<0.05) and can be used to re-canalize the stenostic lacrimal passage.The results show that the ^(125)I radioactive probing is a therapeutical mechanism for radioactive probing strategy for treating nasolacrimal duct stenosis to induce cell apoptosis.
基金Supported by the National Basic Research Program of China under Grant No 2013CB922404the National Natural Science Foundation of China under Grant Nos 11474040 11274053,11474039 and 61178022the Project under Grant No 14KP007
文摘We report the direct imaging of plasmon on the tips pulses and probing of ultrafast plasmon dynamics by of nano-prisms in a bowtie structure excited by 7 fs laser combining the pump-probe technology with three-photon photoemission electron microscopy. Different photoemission patterns induced by the plasmon effect are observed when the bowties are excited by s- and p-polarized femtosecond laser pulses. A series of images of the evolution of local surface plasmon modes on different tips of the bowtie are obtained by the time-resolved three-photon photoemission electron microscopy, and the result discloses that plasmon excitation is dominated by the interfer- ence of the pump and probe pulses within the first 13 fs of the delay time, and thereafter the individual plasmon starts to oscillate on its own characteristic resonant frequencies.
文摘Spatial distribution of acoustic and elastic waves generated by an elementary vibration source at seismic profiling frequencies in an infinite medium close to a layer inclusion, i.e., an extended layer, is numerically simulated. Point dipole radiation in a homogeneous infinite medium separated by a liquid layer of different medium density or acoustic wave velocity is considered. Transverse elastic SH-waves excited by an oscillating power source in a solid medium also located close to the layer of different propagation velocity than the velocity of the vicinity are analyzed. Formulae for the spatial distribution of the wave field amplitude are derived and computer graphics of field distribution images is presented. Wave reflection, penetration deep into the layer inclusion, and transmittance through it are examined. Results of the analysis can be applied to seismoacoustic probing of geologic environment by the near field of a harmonic vibration source.
文摘A fully automatic setup for on-wafer contact probing will be presented. This setup consists of six automatable nano positioning axes used as tool holder and a sample holder. With this setup a fully automatic one-port SOL calibration for a Vector Network Analyzer is done. Furthermore a fully automated on-wafer contact probing is performed. Afterwards, the effects of a misalignment of the three tips of a GSG-probe are examined. Additionally the error on the calibration is calculated to determine its effect on the measurement. The results show, that a misalignment of the probe has a high impact on the measurement of the VNA. Hence a fully automated on-wafer probing presented in this paper is a good way to detect these misalignments and correct them if necessary.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675157,51475131)State Key Laboratory of Precision Measuring Technology and Instruments of China(Grant No.PIL1401)
文摘To satisfy the measuring demands for the micro components of the industry, micro/nano probing systems with various ball tips have been developed. However, most of them cannot be used to measure the real micro geometrical features high precisely because the parameters of the ball tips are not appropriate. The ball tips with a diameter of less than 100 μm, a sphericity and eccentricity of far less than 1 μm are required urgently. A review on the state-of-the-art of ball tips of micro/nano probing systems is presented. The material characteristics and geometric parameters of now available ball tips are introduced sepa- rately. The existing fabrication methods for the ball tips are demonstrated and summarized. The ball tips' future trends, which are smaller diameter, better sphericity and smaller eccentricity, are proposed in view of the practical requirements of high-precision measurement for micro geometrical features. Some challenges have to be faced in future, such as the promotion and high-precision measurement for the small ball tip's sphericity and eccentricity. Fusion method without the gravity effect when the molten ball tip solidifying is a more suitable way to fabricate a small diameter ball tip together with a shaft.
文摘The accessibility of coordinate measuring machines (CMMs) in dimensional inspection is studied. The problem of computing the global accessibility cone is solved using a method of angle representation. Otherwise, the length and volume of probe are considered sufficiently so that all the feasible probe orientations could be determined for the inspection of a workpiece when a touch trigger probe is used and the shortcoming of abstracting a probe as an infinite half line could be overcome completely. In the end, an example is given to explain the method.
基金the Shenzhen Science and Technology Research and Development Funds(No.JCYJ20190806155409104)National Natural Science Foundation of China(Nos.52150222,21672130 and 52073163)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110356)the Qilu Young Scholars Program of Shandong University.
文摘Mitochondrial damage is closely related to the occurrence of many diseases.However,accurate monitoring and reporting of mitochondrial damage are not easy.Here,we developed a small molecule fluorescent probe named CB-Cl,which has splendid spectral properties(large Stokes shift,strong affinity for RNA,etc.)and excellent targeting ability to intracellular mitochondria.After mitochondria were damaged by external stimuli,CB-Cl would light up the nucleolus as a signal reporter.The cascade imaging of mitochondria and nucleolus using CB-Cl can monitor and visualize the mitochondrial status in living cells in real-time.Based on the above advantages,the probe CB-Cl has reference significance for the related research of mitochondrial damage and the prevention and treatment of related diseases.
基金support of the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)National Key Research and Development Program of China(Nos.2019YFA0308000,2020YFA0308800,and 2021YFA1400100)+1 种基金National Natural Science Foundation of China(Nos.92163206,61971035,61725107,and 62271048)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB30000000).
文摘Imaging biomolecules in real space is crucial for gaining a comprehensive understanding of the properties and functions of biological systems at the most fundamental level.Among the various imaging techniques available for biomolecules and their assembled nanostructures,scanning probe microscopy(SPM)provides a powerful and nondestructive imaging option.SPM is unique in visualizing intrinsically disordered biomolecules at the nanometer scale(e.g.,glycans).This review highlights recent achievements in studying biomolecules using SPM technique,focusing on DNA bases,amino acids,proteins,and glycans.The atomic-level analysis of biomolecules made possible by SPM allows for a more accurate definition of the local structure–property relationship.High-resolution SPM imaging of single biomolecules offers a new way to study basic processes of life at the molecular level.
基金This work was financially supported by the National Natural Science Foundation of China(No.31771103)Chinese Academy of Sciences(CAS)Emergency Project of African Swine Fever(ASF)Research(No.KJZD-SW-L07)the Scientific Instrument Developing Project of the CAS(No.YJKYYQ20190057).
文摘Cell membrane integrity is fundamental to the normal activities of cells and is involved in both acute and chronic pathologies.Here,we report a probe for analyzing cell membrane integrity developed from a 9 nm-sized protein nanocage named Dps via fluorophore conjugation with high spatial precision to avoid self-quenching.The probe cannot enter normal live cells but can accumulate in dead or live cells with damaged membranes,which,interestingly,leads to weak cytoplasmic and strong nuclear staining.This differential staining is found attributed to the high affinity of Dps for histones rather than DNA,providing a staining mechanism different from those of known membrane exclusion probes(MEPs).Moreover,the Dps nanoprobe is larger in size and thus applies a more stringent criterion for identifying severe membrane damage than currently available MEPs.This study shows the potential of Dps as a new bioimaging platform for biological and medical analyses.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2019R1I1A1A01063888)the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2019R1A6A1A03033215)F.P.Z.acknowledges the Alexander von Humboldt Foundation(AvH)for the fellowship with award number 1203828,and Z.L.acknowledges the LOEWE program of the State of Hesse,Germany,within the project FLAME(Fermi Level Engineering of Antiferroelectric Materials for Energy Storage and Insulation Systems).
文摘Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses,making this technique advantageous over macroscopic approaches.Despite its widespread application in ferroelectrics,it has rarely been used to investigate the ferrielectric(FiE)behaviors in antiferroelectric(AFE)materials.Herein,the PFM was utilized to study the local electromechanical behavior and distribution of FiE,and the AFE phases of PbZrO_(3)thin-film were studied,where only the FiE behavior is observable using a macroscopic approach.The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages.In contrast,the AFE region only yields an observable response at high voltages.Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations.Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior,thereby providing insights to guide property modification and potential applications.
基金We acknowledge financial support from the ERC program(Grant No.741431-2DNanoSpec).
文摘Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.
基金The authors thank Benli Chai for bioinformatic support and Anthony Gaca and Ami Smith for technical assistance in the laboratory. This study was funded by the US DOE Office of Science under grants DE-FG02-97ER62469, DE-FG02-97ER64398, AC05-00OR22725, and DE-SC0006783. Mary Beth Leigh was supported by a US National Science Foundation postdoctoral fellowship in Microbial Biology.
文摘Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with ^13C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant 13C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U(VI) reduction in the less reduced sample. I3C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron (Ⅲ) reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillus and others, including the known U(VI)-redueing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobac- ter and Desulfosporosinus. The findings suggest that ethanol biostimulates the U(VI)-reducing microbial com- munity by first serving as an electron donor for nitrate, sulfate, iron (IH) and U(VI) reduction, and acetate which then functions as electron donor for U(VI) reduction and carbon source for microbial growth.
基金supported by the National Natural Science Foundation of China(Grant No.31671355)the National Thousand Young Talents Program of China to QCZ
文摘RNA folds into intricate structures that are crucial for its functions and regulations. To date, a multitude of approaches for probing structures of the whole transcriptome, i.e., RNA struc- turomes, have been developed. Applications of these approaches to different cell lines and tissues have generated a rich resource for the study of RNA structure-function relationships at a systems biology level. In this review, we first introduce the designs of these methods and their applications to study different RNA structuromes. We emphasize their technological differences especially their unique advantages and caveats. We then summarize the structural insights in RNA functions and regulations obtained from the studies of RNA structuromes. And finally, we propose potential directions for future improvements and studies.