It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimens...It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimensional(3D)models are relatively straightforward but time-consuming.One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces.In this study,a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured 3D model.A virtual digital image rendering was then employed to capture virtual images of selected regions.This technique helps to overcome limitations caused by the surface morphology of the rock mass,such as restricted access,lighting conditions,and shading effects.After AI-powered trace detection on two-dimensional(2D)images,a 3D data structuring technique was applied to the selected trace pixels.In the 3D data structuring,the trace data were structured through 2D thinning,3D reprojection,clustering,segmentation,and segment linking.Finally,the linked segments were exported as 3D polylines,with each polyline in the output corresponding to a trace.The efficacy of the proposed method was assessed using a 3D model of a real-world case study,which was used to compare the results of artificial intelligence(AI)-aided and human intelligence trace detection.Rosette diagrams,which visualize the distribution of trace orientations,confirmed the high similarity between the automatically and manually generated trace maps.In conclusion,the proposed semi-automatic method was easy to use,fast,and accurate in detecting the dominant jointing system of the rock mass.展开更多
cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5 d]imidazole(BCHMX)is an advanced energetic compound that expected to spread worldwide in the near future.Since,no approved remote detection methods were reported in current ...cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5 d]imidazole(BCHMX)is an advanced energetic compound that expected to spread worldwide in the near future.Since,no approved remote detection methods were reported in current literature for this material,we performed hyper-spectral imaging and laser induced fluorescence(LIF)to a BCHMX sample under low laser fluence for determining the optimum laser wavelength used in any future BCHMX-LIF based remote detection systems.For this purpose,an experimental setup consisted of a sun spectrum lamp and hyper-spectral camera was built to illuminate and image white powder samples of BCHMX in comparison with the traditional explosives,HMX(1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane),RDX(1,3,5-trinitro-1,3,5-triazacyclohexane),PETN(2,2-Bis[(nitroxy)methyl]propane-1,3-diyldinitrate).The imaging reveals strong BCHMX sample absorption contrast among other samples at wavelength ranging from 400 to 410 nm.When light source was replaced by a 405 nm laser diode illuminator,a strong BCHMX sample LIF at the spectral range from 425 to 700 nm was observed under low laser fluence condition of 0.1 mJ/cm^(2).Finally,we demonstrated successfully the ability of the 405 nm LIF and the hyperspectral imaging technique to detect finger print traces of BCHMX on white cellulose fabric from a distance of 15 m and a detection limit of 1 mg/cm^(2).展开更多
Quantitative detection of trace small-sized nanoplastics(<100 nm)remains a significant challenge in surface-enhanced Raman scattering(SERS).To tackle this issue,we developed a hydrophobic CuO@Ag nanowire substrate ...Quantitative detection of trace small-sized nanoplastics(<100 nm)remains a significant challenge in surface-enhanced Raman scattering(SERS).To tackle this issue,we developed a hydrophobic CuO@Ag nanowire substrate and introduced a multiplex-feature analysis strategy based on the coffee ring effect.This substrate not only offers high Raman enhancement but also exhibits a high probability of detection(POD),enabling rapid and accurate identification of 50 nm polystyrene nanoplastics over a broad concentration range(1–10−10 wt%).Importantly,experimental results reveal a strong correlation between the coffee ring formation and the concentration of nanoplastic dispersion.By incorporating Raman signal intensity,coffee ring diameter,and POD as combined features,we established a machine learning-based mapping between nanoplastic concentration and coffee ring characteristics,allowing precise predictions of dispersion concentration.The mean squared error of these predictions is remarkably low,ranging from 0.21 to 0.54,representing a 19 fold improvement in accuracy compared to traditional linear regression-based methods.This strategy effectively integrates SERS with wettability modification techniques,ensuring high sensitivity and fingerprinting capabilities,while addressing the limitations of Raman signal intensity in accurately reflecting concentration changes at ultra-low levels,providing a new idea for precise SERS measurements of nanoplastics.展开更多
Owing to the ppb-level detection standard toward the toxic and harmful gas,the detection of trace gases has become an important subject in the field of indoor environment management.However,the traditional resistive g...Owing to the ppb-level detection standard toward the toxic and harmful gas,the detection of trace gases has become an important subject in the field of indoor environment management.However,the traditional resistive gas sensors hardly meet the requirement due to the weak signal generated by trace gas molecules that are difficult to capture.Herein,a visible-light-assisted Pd/TiO_(2)gas sensor is proposed to endow the effective detection of trace formaldehyde(HCHO)gas without heating temperature.Benefiting from the enhanced photocatalytic properties of TiO_(2)by Pd decoration,the visible-light-assisted Pd/TiO_(2)gas sensor can detect the HCHO gas as low as80×10^(–9)at room temperature.The successful preparation of nanoscale TiO_(2)sensing layer is facilitated by the ultrathin carbon nanotube interdigital electrode in the gas sensor,which avoids the discontinuity of the sensing layer caused by the excessive thickness of the traditional metal electrode.In addition,the whole preparation process of the Pd/TiO_(2)gas sensor with carbon nanotube electrodes is compatible with mainstream CMOS fabrication technology,which is expected to realize the batch fabrication and micro-integrated application of gas sensors.It is expected that our work can provide a new strategy for the batch preparation of high-performance trace HCHO gas sensors and their future applications in portable electronic devices such as smartphones.展开更多
Metal-organic frameworks(MOFs)have attracted widespread interest due to their unique and unprecedented advantages in microstructures and properties.Besides,surface-enhanced Raman scattering(SERS)technology has also ra...Metal-organic frameworks(MOFs)have attracted widespread interest due to their unique and unprecedented advantages in microstructures and properties.Besides,surface-enhanced Raman scattering(SERS)technology has also rapidly developed into a powerful fingerprint spectroscopic technique that can provide rapid,non-invasive,non-destructive,and ultra-sensitive detection,even down to single molecular level.Consequently,a considerable amount of researchers combined MOFs with the SERS technique to further improve the sensing performance and broaden the applications of SERS substrates.Herein,representative synthesis strategies of MOFs to fabricate SERS-active substrates are summarized and their applications in ultra-sensitive biomedical trace detection are also reviewed.Besides,relative barriers,advantages,disadvantages,future trends,and prospects are particularly discussed to give guidance to relevant researchers.展开更多
The hazard of Hg ion pollution triggers the motivation to explore a fast, sensitive, and reliable detection method. Here, we design and fabricate novel 36-nm-thick Ag-Au composite layers alternately deposited on three...The hazard of Hg ion pollution triggers the motivation to explore a fast, sensitive, and reliable detection method. Here, we design and fabricate novel 36-nm-thick Ag-Au composite layers alternately deposited on three-dimensional （3D） periodic SiO2 nanogrids as surface-enhanced Raman scattering （SERS） probes. The SERS effects of the probes depend mainly on the positions and intensities of their localized surface plasmon resonance （LSPR） peaks, which is confirmed by the absorption spectra from finite-difference time-domain （FDTD） calculations. By optimizing the structure and material to maximize the intrinsic electric field enhancement based on the design method of 3D periodic SERS probes proposed, high performance of the Ag-Au/SiO2 nanogrid probes is achieved with the stability further enhanced by annealing. The optimized probes show the outstanding stability with only 4.0% SERS intensity change during 10-day storage, the excellent detection uniformity of 5.78% （RSD）, the detection limit of 5.0 × 10-12 M （1 ppt）, and superior selectivity for Hg ions. The present study renders it possible to realize the rapid and reliable detection of trace heavy metal ions by developing high- performance 3D periodic structure SERS probes by designing novel 3D structure and optimizing plasmonic material.展开更多
An effective surface enhanced Raman scattering（SERS） substrate is designed and fabricated by synthesis of Si O2 nanorods array via glancing angle deposition, followed by coating Au nanoparticles onto Si O2 surface i...An effective surface enhanced Raman scattering（SERS） substrate is designed and fabricated by synthesis of Si O2 nanorods array via glancing angle deposition, followed by coating Au nanoparticles onto Si O2 surface in order to create numerous ＂hot spots＂. The detecting sensitivity of such substrate could be optimized by simply adjusting the deposition time of Au. Thus, it can be used for detection of Rhodamine 6G at concentration as low as 10^-9M. Furthermore, our SERS substrate is applied to detect 5 μg/g polychlorinated biphenyls in soil sample, which proves its potential for trace environmental pollutants detection.展开更多
Analytical difficulties encountered in the determination of ethyl carbamate, a known cancinogen, in a wide variety of wines and spirits have been overcome by spe- cific, sensitive GC/GC and CC/CC/MS methods with a rel...Analytical difficulties encountered in the determination of ethyl carbamate, a known cancinogen, in a wide variety of wines and spirits have been overcome by spe- cific, sensitive GC/GC and CC/CC/MS methods with a relatively shorter extraction procedure. The lowest detection limits were estimated to be 0. 1 and 0. 01μg/L for GC/GC and GC/GC/MS respectively. The RSD of the GC/GC method was 2. 5%.展开更多
A quite new type of chelating resin Carboxymethylated Polyethylenimine-Polymethylenepolyphenylene Isocyanate(CPPI)is used for the preconcentration of Zn from high salt water such as seawater. The preconcentration is c...A quite new type of chelating resin Carboxymethylated Polyethylenimine-Polymethylenepolyphenylene Isocyanate(CPPI)is used for the preconcentration of Zn from high salt water such as seawater. The preconcentration is controlled through the technique of Flow Injection Analysis(FIA).The concentrated sample solution is then directly transferred to an Inductively Coupled Plasma-Atomic Fluorescence Spectrometer(ICP-AFS)for determination.The detection limit of Zn by the technique is about 0.06 ppb.展开更多
CF_(4)is a major decomposition product of the insulating gas in C_(4)F_(7)N-insulated gasinsulated metal-enclosed switchgear(GIS)during partial discharge or overheating faults.Its detection is essential for effective ...CF_(4)is a major decomposition product of the insulating gas in C_(4)F_(7)N-insulated gasinsulated metal-enclosed switchgear(GIS)during partial discharge or overheating faults.Its detection is essential for effective online monitoring and fault diagnosis of GIS.However,the application of photoacoustic spectroscopy for CF_(4)detection is hampered by significant cross-interference from the background C_(4)F_(7)N gas.In this paper,quantum chemical calculations revealed that C_(4)F_(7)N hydrolyses to form perfluoroisobutyrate and ammonia under base catalysis,exhibiting a low reaction energy barrier and high Gibbs free energy change,indicating ease of initiation and substantial reaction extent.This chemical specificity,unlike the stable CF_(4)which does not undergo such a reaction,enables selective purification of the gas to be detected through this hydrolysis reaction.Leveraging this insight,an experimental system was constructed that cascades chemical absorption purification with photoacoustic spectroscopy detection.This system effectively mitigates the cross-interference of C_(4)F_(7)N in CF_(4)detection by selectively absorbing C_(4)F_(7)N with over 95%efficiency through a base-catalysed nucleophilic hydrolysis reaction.This enabled the precise detection of trace amounts of CF_(4)against a substantial background of C_(4)F_(7)N with a detection limit reaching 14.79μL/L.This advancement offers support for the online monitoring and fault diagnosis of eco-friendly GIS.展开更多
Superhydrophobic surface(SHS) has been well developed, as SHS renders the property of minimizing the water/solid contact interface. Water droplets deposited onto SHS with contact angles exceeding 150°, allow them...Superhydrophobic surface(SHS) has been well developed, as SHS renders the property of minimizing the water/solid contact interface. Water droplets deposited onto SHS with contact angles exceeding 150°, allow them to retain spherical shapes, and the low adhesion of SHS facilitates easy droplet collection when tilting the substrate. These characteristics make SHS suitable for a wide range of applications. One particularly promising application is the fabrication of microsphere and supraparticle materials. SHS offers a distinct advantage as a universal platform capable of providing customized services for a variety of microspheres and supraparticles. In this review, an overview of the strategies for fabricating microspheres and supraparticles with the aid of SHS, including cross-linking process, polymer melting,and droplet template evaporation methods, is first presented. Then, the applications of microspheres and supraparticles formed onto SHS are discussed in detail, for example, fabricating photonic devices with controllable structures and tunable structural colors, acting as catalysts with emerging or synergetic properties, being integrated into the biomedical field to construct the devices with different medicinal purposes, being utilized for inducing protein crystallization and detecting trace amounts of analytes. Finally,the perspective on future developments involved with this research field is given, along with some obstacles and opportunities.展开更多
The ecological environment suffers from multiple pollution from many aspects,and the heavy metal ions(HMI)pose a significant threat to human health.Detecting these ions is challenging due to their trace amounts and di...The ecological environment suffers from multiple pollution from many aspects,and the heavy metal ions(HMI)pose a significant threat to human health.Detecting these ions is challenging due to their trace amounts and diverse types.Optical fiber sensors offer numerous advantages over conventional techniques in HMI sensing,including small size,quick response,resistance to electromagnetic interference,and long-range monitoring capabilities.In this paper,several optical methods for HMI detection have been described,namely fluorescence,fiber grating,fiber modal interference,surface plasmon resonance,and optical absorbance.The principles,structures,and sensitive materials of these methods are discussed in detail.The advantages and disadvantages of each approach are illustrated to facilitate a better comparison.Furthermore,the current status and future directions for the development of HMI optical fiber sensors are also discussed,which could enlighten the future HMI sensor design.展开更多
Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy （CRDS）. By using ...Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy （CRDS）. By using different absorption lines of H20 in the 1.56 and 1.36 gm regions, we are able to determine the relative concentration （mole fraction） of water vapor from a few percent down to the 10-12 level. The quantitative accuracy is examined by comparing the CRDS hygrometer with a commercial chilled-mirror dew-point meter. The high sensitivity of the CRDS instrument allows a water detection limit of 8 pptv.展开更多
Nano Research volume 13,pages1704–1712(2020)Cite this article 191 Accesses Metrics details Abstract Intelligent gas sensors based on the layered transition metal dichalcogenides(TMDs)have attracted great interest in ...Nano Research volume 13,pages1704–1712(2020)Cite this article 191 Accesses Metrics details Abstract Intelligent gas sensors based on the layered transition metal dichalcogenides(TMDs)have attracted great interest in the field of gas sensing due to their multiple active sites,fast electron,mass transfer capability and large surface-to-volume ratio.However,conventional TMDs-based sensors typically work at elevated temperature in inert atmosphere,which would largely limit the corresponding practical applications.Herein,novel oxygen-doped MoSe2 hierarchical nanostructures composed of ultrathin nanosheets with large specific surface area have been designed and generated typically at 200°C in air for fast and facile gas sensing of trimethylamine(TMA),effectively.Benefited from the gas-accessible hierarchical morphology and high surface area with abundant nanochannels,highly sensitive and selective detection of trace TMA has been achieved under ambient condition,and as detected the theoretical limit of detection(LOD)is 8 ppb,which is the lowest for TMA detection under ambient condition among the reported studies.The mechanism of oxygen doping on the improved gas-sensing performance has been investigated,revealing that the oxygen doping could greatly optimize the electronic structure,thus regulate the Fermi level of MoSe2 as well as the affinity between TMA molecule and sensor surface.It is expected that the oxygen doping strategy developed for the highly efficient gas sensors based on TMDs in present work may also be applicable to other types of gas-sensing semiconductors,which could open up a new direction for the rational design of high-performance gas sensors working under ambient condition.展开更多
A trace ammonia(NH3)detection system based on the near-infrared fiber-optic cantilever-enhanced photoacoustic spectroscopy(CEPAS)is proposed.A fiber-optic extrinsic Fabry-Perot interferometer(EFPI)based cantilever mic...A trace ammonia(NH3)detection system based on the near-infrared fiber-optic cantilever-enhanced photoacoustic spectroscopy(CEPAS)is proposed.A fiber-optic extrinsic Fabry-Perot interferometer(EFPI)based cantilever microphone has been designed to detect the photoacoustic pressure signal.The microphone has many advantages,such as small size and high sensitivity.A near-infrared tunable erbium-doped fiber laser(EDFL)amplified by an erbium-doped fiber amplifier(EDFA)is used as a photoacoustic excitation light source.To improve the sensitivity,the photoacoustic signal is enhanced by a photoacoustic cell with a resonant frequency of 1624 Hz.When the wavelength modulation spectroscopy(WMS)technique is applied,the weak photoacoustic signal is detected by the second-harmonic detection technique.Trace NH3 measurement experiments demonstrate that the designed fiber-optic CEPAS system has a linear response to concentrations in the range of 0 ppm‒20 ppm at the wavelength of 1522.448 nm.Moreover,the detection limit is estimated to be 3.2 ppb for a lock-in integration time of 30 s.展开更多
Miniaturized laser spectroscopy capable of in situ and real-time ppb-level trace gas sensing is of fundamental importance for numerous applications,including environment monitoring,industry process control,and biomedi...Miniaturized laser spectroscopy capable of in situ and real-time ppb-level trace gas sensing is of fundamental importance for numerous applications,including environment monitoring,industry process control,and biomedical diagnosis.Benchtop laser spectroscopy systems based on direct absorption,photoacoustic,and Raman effects exhibit high sensitivity but face challenges for in situ and real-time gas sensing due to their bulky size,slow response,and offline sampling.We demonstrate a microscale highperformance all-fiber photoacoustic spectrometer integrating the key components,i.e.,the photoacoustic gas cell and the optical microphone,into a single optical fiber tip with a diameter of 125μm.Without a long optical path to enhance the light–gas interaction,the fiber-tip gas cell with acoustic-hard boundary tightly confines and amplifies the local photoacoustic wave,compensating for the sensitivity loss during miniaturization.This localized acoustic wave is demodulated by high-sensitivity fiber-optic interferometry,enabling a∼9 ppb detection limit for acetylene gas approaching the benchtop system.The microscale fiber spectrometer also exhibits a short response time of∼18 ms and a subnanoliter sample volume,not only suitable for routine realtime in situ trace gas measurement but also inspiring new applications such as two-dimensional gas flow concentration mapping and in vivo intravascular blood gas monitoring as showcased.展开更多
Axonal tracing is useful for detecting optic nerve injury and regeneration,but many commonly used methods cannot be used to observe axoplasmic flow and synaptic transmission in vivo.Manganese（Mn^2＋）-enhanced magnet...Axonal tracing is useful for detecting optic nerve injury and regeneration,but many commonly used methods cannot be used to observe axoplasmic flow and synaptic transmission in vivo.Manganese（Mn^2＋）-enhanced magnetic resonance imaging（MEMRI） can be used for in vivo longitudinal tracing of the visual pathway.Here,we explored the dose response and time course of an intravitreal injection of Mn Cl2 for tracing the visual pathway in rabbits in vivo using MEMRI.We found that 2 m M Mn Cl2 enhanced images of the optic nerve but not the lateral geniculate body or superior colliculus,whereas at all other doses tested（5–40 m M）,images of the visual pathway from the retina to the contralateral superior colliculus were significantly enhanced.The images were brightest at 24 hours,and then decreased in brightness until the end of the experiment（7 days）.No signal enhancement was observed in the visual cortex at any concentration of Mn Cl2.These results suggest that MEMRI is a viable method for temporospatial tracing of the visual pathway in vivo.Signal enhancement in MEMRI depends on the dose of Mn Cl2,and the strongest signals appear 24 hours after intravitreal injection.展开更多
Surface-enhanced Raman spectroscopy （SERS） is a fast analytical technique for trace chemicals; however, it requires the active SERS-substrates to adsorb analytes, thus limiting target species to those with the desir...Surface-enhanced Raman spectroscopy （SERS） is a fast analytical technique for trace chemicals; however, it requires the active SERS-substrates to adsorb analytes, thus limiting target species to those with the desired affinity for substrates. Here we present networked polyacrylic acid sodium salt （PAAS） film entrapped Ag-nanocubes （denoted as Ag-nanocubes@PAAS） as an effective SERS-substrate for analytes with and without high affinity. Once the analyte aqueous solution is cast on the dry Ag-nanocubes@PAAS substrate, the bibulous PAAS becomes swollen forcing the Ag-nanocubes loose, while the analytes diffuse in the interstices among the Ag-nanocubes. When dried, the PAAS shrinks and pulls the Ag-nanocubes back to their previous aggregated state, while the PAAS network ＂detains＂ the analytes in the small gaps between the Ag-nanocubes for SERS detection. The strategy has been proven effective for not only single- analytes but also multi-analytes without strong affinity for Ag, showing its potential in SERS-based simultaneous multi-analyte detection of both adsorbable and non-adsorbable pollutants in the environment.展开更多
Detecting trace pesticide residues in food products is crucial for ensuring food safety.Terahertz technology has demonstrated significant advantages in chemical and biological sensing by utilizing the vibrational sign...Detecting trace pesticide residues in food products is crucial for ensuring food safety.Terahertz technology has demonstrated significant advantages in chemical and biological sensing by utilizing the vibrational signatures inherent to molecules in the terahertz spectrum and leveraging the amplified electric fields facilitated by metamaterials.In this work,we introduce a novel method for imidacloprid(IMI)pesticide residue detection using the rod-shaped terahertz metamaterial(RSTM)with a composite interface of gold and conductive polymer polyaniline(PANI).The core mechanism of this method relies on the binding of IMI to PANI,which alters the resonance intensity and frequency of the Au-PANI-RSTM.Specifically,the RSTM parameters are determined using computer simulation technology(CST),and the RSTM structure is engraved on the Au-PANI surface using laser direct writing technology.Further characterization using mid-infrared spectroscopy(MIR)and X-ray photoelectron spectroscopy(XPS)techniques reveals that the stable bonding between PANI and IMI is facilitated by hydrogen bonding and covalent bonding.The detection limit of Au-PANI-RSTM deposited with 20 segments for IMI is 0.46 ppm,which complies with the maximum residue limit for IMI stipulated in the Chinese National Standard.展开更多
The hybridization chain reaction(HCR)is a widely used nucleic acid amplification technique that is essential for gene expression analysis and disease diagnosis.Despite its inherent stability,traditional HCR often suff...The hybridization chain reaction(HCR)is a widely used nucleic acid amplification technique that is essential for gene expression analysis and disease diagnosis.Despite its inherent stability,traditional HCR often suffers from low detection efficiency,which necessitates the use of supplementary molecular technologies to enhance its performance for detecting trace samples.Drawing insights from confinement theory,we have proposed a novel cruciform DNA scaffold-based HCR reaction system(C-HCR).In our approach,the DNA cruciform is assembled with the initiating probes of the HCR reaction through specific binding between adenine-rich and thymine-rich regions.This assembly with derived chains does not interfere with the HCR process.When a target is present,traditional HCR reactions yield long-chain linear products.However,the incorporation of the DNA cruciform in C-HCR leads to the formation of network-like products,which create favorable conditions for efficient molecular collisions and,in turn,promote high detection efficiency within the system.We utilized miR-21 and miR-27a as model targets to validate our design concept.Our results revealed that the miRNA-specific HCR system for miR-21 and miR-27a achieved significant increases in detection efficiency of 27.8%and 50%,respectively,demonstrating the feasibility and versatility of our design.This study offers a new strategy for enzyme-free amplification systems.展开更多
基金supported by grants from the Human Resources Development program (Grant No.20204010600250)the Training Program of CCUS for the Green Growth (Grant No.20214000000500)by the Korea Institute of Energy Technology Evaluation and Planning (KETEP)funded by the Ministry of Trade,Industry,and Energy of the Korean Government (MOTIE).
文摘It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimensional(3D)models are relatively straightforward but time-consuming.One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces.In this study,a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured 3D model.A virtual digital image rendering was then employed to capture virtual images of selected regions.This technique helps to overcome limitations caused by the surface morphology of the rock mass,such as restricted access,lighting conditions,and shading effects.After AI-powered trace detection on two-dimensional(2D)images,a 3D data structuring technique was applied to the selected trace pixels.In the 3D data structuring,the trace data were structured through 2D thinning,3D reprojection,clustering,segmentation,and segment linking.Finally,the linked segments were exported as 3D polylines,with each polyline in the output corresponding to a trace.The efficacy of the proposed method was assessed using a 3D model of a real-world case study,which was used to compare the results of artificial intelligence(AI)-aided and human intelligence trace detection.Rosette diagrams,which visualize the distribution of trace orientations,confirmed the high similarity between the automatically and manually generated trace maps.In conclusion,the proposed semi-automatic method was easy to use,fast,and accurate in detecting the dominant jointing system of the rock mass.
文摘cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5 d]imidazole(BCHMX)is an advanced energetic compound that expected to spread worldwide in the near future.Since,no approved remote detection methods were reported in current literature for this material,we performed hyper-spectral imaging and laser induced fluorescence(LIF)to a BCHMX sample under low laser fluence for determining the optimum laser wavelength used in any future BCHMX-LIF based remote detection systems.For this purpose,an experimental setup consisted of a sun spectrum lamp and hyper-spectral camera was built to illuminate and image white powder samples of BCHMX in comparison with the traditional explosives,HMX(1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane),RDX(1,3,5-trinitro-1,3,5-triazacyclohexane),PETN(2,2-Bis[(nitroxy)methyl]propane-1,3-diyldinitrate).The imaging reveals strong BCHMX sample absorption contrast among other samples at wavelength ranging from 400 to 410 nm.When light source was replaced by a 405 nm laser diode illuminator,a strong BCHMX sample LIF at the spectral range from 425 to 700 nm was observed under low laser fluence condition of 0.1 mJ/cm^(2).Finally,we demonstrated successfully the ability of the 405 nm LIF and the hyperspectral imaging technique to detect finger print traces of BCHMX on white cellulose fabric from a distance of 15 m and a detection limit of 1 mg/cm^(2).
基金the National Natural Science Foundation of China(No.12174229 and 22375117)Natural Science Foundation of Shandong Province(No.ZR2022YQ02 and ZR2023MB149)Taishan Scholars Program of Shandong Province(No.tsqn202306152)for financial support.
文摘Quantitative detection of trace small-sized nanoplastics(<100 nm)remains a significant challenge in surface-enhanced Raman scattering(SERS).To tackle this issue,we developed a hydrophobic CuO@Ag nanowire substrate and introduced a multiplex-feature analysis strategy based on the coffee ring effect.This substrate not only offers high Raman enhancement but also exhibits a high probability of detection(POD),enabling rapid and accurate identification of 50 nm polystyrene nanoplastics over a broad concentration range(1–10−10 wt%).Importantly,experimental results reveal a strong correlation between the coffee ring formation and the concentration of nanoplastic dispersion.By incorporating Raman signal intensity,coffee ring diameter,and POD as combined features,we established a machine learning-based mapping between nanoplastic concentration and coffee ring characteristics,allowing precise predictions of dispersion concentration.The mean squared error of these predictions is remarkably low,ranging from 0.21 to 0.54,representing a 19 fold improvement in accuracy compared to traditional linear regression-based methods.This strategy effectively integrates SERS with wettability modification techniques,ensuring high sensitivity and fingerprinting capabilities,while addressing the limitations of Raman signal intensity in accurately reflecting concentration changes at ultra-low levels,providing a new idea for precise SERS measurements of nanoplastics.
基金financially supported by the National Natural Science Foundation of China(Nos.62071410 and 62101477)Hunan Provincial Natural Science Foundation(No.2021JJ40542)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20210627)。
文摘Owing to the ppb-level detection standard toward the toxic and harmful gas,the detection of trace gases has become an important subject in the field of indoor environment management.However,the traditional resistive gas sensors hardly meet the requirement due to the weak signal generated by trace gas molecules that are difficult to capture.Herein,a visible-light-assisted Pd/TiO_(2)gas sensor is proposed to endow the effective detection of trace formaldehyde(HCHO)gas without heating temperature.Benefiting from the enhanced photocatalytic properties of TiO_(2)by Pd decoration,the visible-light-assisted Pd/TiO_(2)gas sensor can detect the HCHO gas as low as80×10^(–9)at room temperature.The successful preparation of nanoscale TiO_(2)sensing layer is facilitated by the ultrathin carbon nanotube interdigital electrode in the gas sensor,which avoids the discontinuity of the sensing layer caused by the excessive thickness of the traditional metal electrode.In addition,the whole preparation process of the Pd/TiO_(2)gas sensor with carbon nanotube electrodes is compatible with mainstream CMOS fabrication technology,which is expected to realize the batch fabrication and micro-integrated application of gas sensors.It is expected that our work can provide a new strategy for the batch preparation of high-performance trace HCHO gas sensors and their future applications in portable electronic devices such as smartphones.
基金supported by the National Basic Research Program of China(No.2017YFA0205304)the National Natural Science Foundation of China(Nos.82020108017 and 81921002)+3 种基金the Shanghai Sailing Program(No.22YF1431100)the Medical Engineering Cross Project of Shanghai Jiao Tong University(Nos.YG2016ZD10,ZH2018QNA51,and ZH2018QNA28)supported by the“Belt and Road”Young Scientist Exchange Program of the Science and Technology Commission of Shanghai(No.18410741600)the Shanghai Science Foundation(No.20142201300).
文摘Metal-organic frameworks(MOFs)have attracted widespread interest due to their unique and unprecedented advantages in microstructures and properties.Besides,surface-enhanced Raman scattering(SERS)technology has also rapidly developed into a powerful fingerprint spectroscopic technique that can provide rapid,non-invasive,non-destructive,and ultra-sensitive detection,even down to single molecular level.Consequently,a considerable amount of researchers combined MOFs with the SERS technique to further improve the sensing performance and broaden the applications of SERS substrates.Herein,representative synthesis strategies of MOFs to fabricate SERS-active substrates are summarized and their applications in ultra-sensitive biomedical trace detection are also reviewed.Besides,relative barriers,advantages,disadvantages,future trends,and prospects are particularly discussed to give guidance to relevant researchers.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0207104)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA09040101)+2 种基金the National Natural Science Foundation of China(Grant No.Y6061111JJ)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2015030)the Key Technology Talent Program of Chinese Academy of Sciences(Grant Nos.Y8482911ZX and Y7602921ZX)
文摘The hazard of Hg ion pollution triggers the motivation to explore a fast, sensitive, and reliable detection method. Here, we design and fabricate novel 36-nm-thick Ag-Au composite layers alternately deposited on three-dimensional （3D） periodic SiO2 nanogrids as surface-enhanced Raman scattering （SERS） probes. The SERS effects of the probes depend mainly on the positions and intensities of their localized surface plasmon resonance （LSPR） peaks, which is confirmed by the absorption spectra from finite-difference time-domain （FDTD） calculations. By optimizing the structure and material to maximize the intrinsic electric field enhancement based on the design method of 3D periodic SERS probes proposed, high performance of the Ag-Au/SiO2 nanogrid probes is achieved with the stability further enhanced by annealing. The optimized probes show the outstanding stability with only 4.0% SERS intensity change during 10-day storage, the excellent detection uniformity of 5.78% （RSD）, the detection limit of 5.0 × 10-12 M （1 ppt）, and superior selectivity for Hg ions. The present study renders it possible to realize the rapid and reliable detection of trace heavy metal ions by developing high- performance 3D periodic structure SERS probes by designing novel 3D structure and optimizing plasmonic material.
基金supported by the National Basic Research Program of China(Grant No.2013CB934301)the National Natural Science Foundation of China(Grant No.50931002)+1 种基金the Research Project of Chinese Ministry of Education(Grant No.113007A)the Initiative Scientific Research Program of Tsinghua University,China
文摘An effective surface enhanced Raman scattering（SERS） substrate is designed and fabricated by synthesis of Si O2 nanorods array via glancing angle deposition, followed by coating Au nanoparticles onto Si O2 surface in order to create numerous ＂hot spots＂. The detecting sensitivity of such substrate could be optimized by simply adjusting the deposition time of Au. Thus, it can be used for detection of Rhodamine 6G at concentration as low as 10^-9M. Furthermore, our SERS substrate is applied to detect 5 μg/g polychlorinated biphenyls in soil sample, which proves its potential for trace environmental pollutants detection.
文摘Analytical difficulties encountered in the determination of ethyl carbamate, a known cancinogen, in a wide variety of wines and spirits have been overcome by spe- cific, sensitive GC/GC and CC/CC/MS methods with a relatively shorter extraction procedure. The lowest detection limits were estimated to be 0. 1 and 0. 01μg/L for GC/GC and GC/GC/MS respectively. The RSD of the GC/GC method was 2. 5%.
文摘A quite new type of chelating resin Carboxymethylated Polyethylenimine-Polymethylenepolyphenylene Isocyanate(CPPI)is used for the preconcentration of Zn from high salt water such as seawater. The preconcentration is controlled through the technique of Flow Injection Analysis(FIA).The concentrated sample solution is then directly transferred to an Inductively Coupled Plasma-Atomic Fluorescence Spectrometer(ICP-AFS)for determination.The detection limit of Zn by the technique is about 0.06 ppb.
基金Science and Technology Project of State Grid Corporation of China(SGCC),Grant/Award Number:5500-202355794A-3-8-KJ。
文摘CF_(4)is a major decomposition product of the insulating gas in C_(4)F_(7)N-insulated gasinsulated metal-enclosed switchgear(GIS)during partial discharge or overheating faults.Its detection is essential for effective online monitoring and fault diagnosis of GIS.However,the application of photoacoustic spectroscopy for CF_(4)detection is hampered by significant cross-interference from the background C_(4)F_(7)N gas.In this paper,quantum chemical calculations revealed that C_(4)F_(7)N hydrolyses to form perfluoroisobutyrate and ammonia under base catalysis,exhibiting a low reaction energy barrier and high Gibbs free energy change,indicating ease of initiation and substantial reaction extent.This chemical specificity,unlike the stable CF_(4)which does not undergo such a reaction,enables selective purification of the gas to be detected through this hydrolysis reaction.Leveraging this insight,an experimental system was constructed that cascades chemical absorption purification with photoacoustic spectroscopy detection.This system effectively mitigates the cross-interference of C_(4)F_(7)N in CF_(4)detection by selectively absorbing C_(4)F_(7)N with over 95%efficiency through a base-catalysed nucleophilic hydrolysis reaction.This enabled the precise detection of trace amounts of CF_(4)against a substantial background of C_(4)F_(7)N with a detection limit reaching 14.79μL/L.This advancement offers support for the online monitoring and fault diagnosis of eco-friendly GIS.
基金the financial support from Shenzhen Science and Technology Program (JCYJ20210324142210027, X.D.)the National Natural Science Foundation of China (52103136, 22275028, U22A20153, 22102017, 22302033, and 52106194)+5 种基金the Sichuan Outstanding Young Scholars Foundation (2021JDJQ0013)Natural Science Foundation of Sichuan Province (2022NSFSC1271)Sichuan Science and Technology Program (2023JDRC0082)“Oncology Medical Engineering Innovation Foundation” project of University of Electronic Science and Technology of China and Sichuan Cancer Hospital (ZYGX2021YGCX009)“Medical and Industrial Cross Foundation” of University of Electronic Science and Technology of China and Sichuan Provincial People’s Hospital (ZYGX2021YGLH207)Shandong Key R&D grant (2022CXGC010509)。
文摘Superhydrophobic surface(SHS) has been well developed, as SHS renders the property of minimizing the water/solid contact interface. Water droplets deposited onto SHS with contact angles exceeding 150°, allow them to retain spherical shapes, and the low adhesion of SHS facilitates easy droplet collection when tilting the substrate. These characteristics make SHS suitable for a wide range of applications. One particularly promising application is the fabrication of microsphere and supraparticle materials. SHS offers a distinct advantage as a universal platform capable of providing customized services for a variety of microspheres and supraparticles. In this review, an overview of the strategies for fabricating microspheres and supraparticles with the aid of SHS, including cross-linking process, polymer melting,and droplet template evaporation methods, is first presented. Then, the applications of microspheres and supraparticles formed onto SHS are discussed in detail, for example, fabricating photonic devices with controllable structures and tunable structural colors, acting as catalysts with emerging or synergetic properties, being integrated into the biomedical field to construct the devices with different medicinal purposes, being utilized for inducing protein crystallization and detecting trace amounts of analytes. Finally,the perspective on future developments involved with this research field is given, along with some obstacles and opportunities.
文摘The ecological environment suffers from multiple pollution from many aspects,and the heavy metal ions(HMI)pose a significant threat to human health.Detecting these ions is challenging due to their trace amounts and diverse types.Optical fiber sensors offer numerous advantages over conventional techniques in HMI sensing,including small size,quick response,resistance to electromagnetic interference,and long-range monitoring capabilities.In this paper,several optical methods for HMI detection have been described,namely fluorescence,fiber grating,fiber modal interference,surface plasmon resonance,and optical absorbance.The principles,structures,and sensitive materials of these methods are discussed in detail.The advantages and disadvantages of each approach are illustrated to facilitate a better comparison.Furthermore,the current status and future directions for the development of HMI optical fiber sensors are also discussed,which could enlighten the future HMI sensor design.
基金This work was supported by the National Basic Research Program of China （No.2013BAK12B00 and No.2013CB834602） and the National Natural Science Foundation of China （No.21225314 and No.21427804）.
文摘Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy （CRDS）. By using different absorption lines of H20 in the 1.56 and 1.36 gm regions, we are able to determine the relative concentration （mole fraction） of water vapor from a few percent down to the 10-12 level. The quantitative accuracy is examined by comparing the CRDS hygrometer with a commercial chilled-mirror dew-point meter. The high sensitivity of the CRDS instrument allows a water detection limit of 8 pptv.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U1932150 and 21571166)Anhui Provincial Natural Science Foundation(No.1908085QB72)the Fundamental Research Funds for the Central Universities(No.WK2060190099).
文摘Nano Research volume 13,pages1704–1712(2020)Cite this article 191 Accesses Metrics details Abstract Intelligent gas sensors based on the layered transition metal dichalcogenides(TMDs)have attracted great interest in the field of gas sensing due to their multiple active sites,fast electron,mass transfer capability and large surface-to-volume ratio.However,conventional TMDs-based sensors typically work at elevated temperature in inert atmosphere,which would largely limit the corresponding practical applications.Herein,novel oxygen-doped MoSe2 hierarchical nanostructures composed of ultrathin nanosheets with large specific surface area have been designed and generated typically at 200°C in air for fast and facile gas sensing of trimethylamine(TMA),effectively.Benefited from the gas-accessible hierarchical morphology and high surface area with abundant nanochannels,highly sensitive and selective detection of trace TMA has been achieved under ambient condition,and as detected the theoretical limit of detection(LOD)is 8 ppb,which is the lowest for TMA detection under ambient condition among the reported studies.The mechanism of oxygen doping on the improved gas-sensing performance has been investigated,revealing that the oxygen doping could greatly optimize the electronic structure,thus regulate the Fermi level of MoSe2 as well as the affinity between TMA molecule and sensor surface.It is expected that the oxygen doping strategy developed for the highly efficient gas sensors based on TMDs in present work may also be applicable to other types of gas-sensing semiconductors,which could open up a new direction for the rational design of high-performance gas sensors working under ambient condition.
基金This work is supported by the Fundamental Research Funds for the Central Universities[Grant No.DUT 18RC(4)040].
文摘A trace ammonia(NH3)detection system based on the near-infrared fiber-optic cantilever-enhanced photoacoustic spectroscopy(CEPAS)is proposed.A fiber-optic extrinsic Fabry-Perot interferometer(EFPI)based cantilever microphone has been designed to detect the photoacoustic pressure signal.The microphone has many advantages,such as small size and high sensitivity.A near-infrared tunable erbium-doped fiber laser(EDFL)amplified by an erbium-doped fiber amplifier(EDFA)is used as a photoacoustic excitation light source.To improve the sensitivity,the photoacoustic signal is enhanced by a photoacoustic cell with a resonant frequency of 1624 Hz.When the wavelength modulation spectroscopy(WMS)technique is applied,the weak photoacoustic signal is detected by the second-harmonic detection technique.Trace NH3 measurement experiments demonstrate that the designed fiber-optic CEPAS system has a linear response to concentrations in the range of 0 ppm‒20 ppm at the wavelength of 1522.448 nm.Moreover,the detection limit is estimated to be 3.2 ppb for a lock-in integration time of 30 s.
基金supported by the National Natural Science Foundation of China(Grant Nos.62275106 and 62135006)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(Grant No.2019BT02X105)+1 种基金the Natural Science Foundation of Guangdong Province(Grant Nos.2022A1515010105 and 2023A1515011415)the Doctoral Students Top Innovative Talent Training Program of Jinan University(Grant No.2023CXB016).
文摘Miniaturized laser spectroscopy capable of in situ and real-time ppb-level trace gas sensing is of fundamental importance for numerous applications,including environment monitoring,industry process control,and biomedical diagnosis.Benchtop laser spectroscopy systems based on direct absorption,photoacoustic,and Raman effects exhibit high sensitivity but face challenges for in situ and real-time gas sensing due to their bulky size,slow response,and offline sampling.We demonstrate a microscale highperformance all-fiber photoacoustic spectrometer integrating the key components,i.e.,the photoacoustic gas cell and the optical microphone,into a single optical fiber tip with a diameter of 125μm.Without a long optical path to enhance the light–gas interaction,the fiber-tip gas cell with acoustic-hard boundary tightly confines and amplifies the local photoacoustic wave,compensating for the sensitivity loss during miniaturization.This localized acoustic wave is demodulated by high-sensitivity fiber-optic interferometry,enabling a∼9 ppb detection limit for acetylene gas approaching the benchtop system.The microscale fiber spectrometer also exhibits a short response time of∼18 ms and a subnanoliter sample volume,not only suitable for routine realtime in situ trace gas measurement but also inspiring new applications such as two-dimensional gas flow concentration mapping and in vivo intravascular blood gas monitoring as showcased.
基金supported by a grant from the National Basic Research Program of China(973 Program)No.2011CB707506+1 种基金the Seed Fund from the Peking University Third Hospital of China,No.YZZ08-9-13the Linghu Fund from the Peking University Third Hospital of China,No.64508-01
文摘Axonal tracing is useful for detecting optic nerve injury and regeneration,but many commonly used methods cannot be used to observe axoplasmic flow and synaptic transmission in vivo.Manganese（Mn^2＋）-enhanced magnetic resonance imaging（MEMRI） can be used for in vivo longitudinal tracing of the visual pathway.Here,we explored the dose response and time course of an intravitreal injection of Mn Cl2 for tracing the visual pathway in rabbits in vivo using MEMRI.We found that 2 m M Mn Cl2 enhanced images of the optic nerve but not the lateral geniculate body or superior colliculus,whereas at all other doses tested（5–40 m M）,images of the visual pathway from the retina to the contralateral superior colliculus were significantly enhanced.The images were brightest at 24 hours,and then decreased in brightness until the end of the experiment（7 days）.No signal enhancement was observed in the visual cortex at any concentration of Mn Cl2.These results suggest that MEMRI is a viable method for temporospatial tracing of the visual pathway in vivo.Signal enhancement in MEMRI depends on the dose of Mn Cl2,and the strongest signals appear 24 hours after intravitreal injection.
文摘Surface-enhanced Raman spectroscopy （SERS） is a fast analytical technique for trace chemicals; however, it requires the active SERS-substrates to adsorb analytes, thus limiting target species to those with the desired affinity for substrates. Here we present networked polyacrylic acid sodium salt （PAAS） film entrapped Ag-nanocubes （denoted as Ag-nanocubes@PAAS） as an effective SERS-substrate for analytes with and without high affinity. Once the analyte aqueous solution is cast on the dry Ag-nanocubes@PAAS substrate, the bibulous PAAS becomes swollen forcing the Ag-nanocubes loose, while the analytes diffuse in the interstices among the Ag-nanocubes. When dried, the PAAS shrinks and pulls the Ag-nanocubes back to their previous aggregated state, while the PAAS network ＂detains＂ the analytes in the small gaps between the Ag-nanocubes for SERS detection. The strategy has been proven effective for not only single- analytes but also multi-analytes without strong affinity for Ag, showing its potential in SERS-based simultaneous multi-analyte detection of both adsorbable and non-adsorbable pollutants in the environment.
基金supported by the National Key Laboratory of Agricultural Equipment Technologysupported by the National Natural Science Foundation of China(32271979)。
文摘Detecting trace pesticide residues in food products is crucial for ensuring food safety.Terahertz technology has demonstrated significant advantages in chemical and biological sensing by utilizing the vibrational signatures inherent to molecules in the terahertz spectrum and leveraging the amplified electric fields facilitated by metamaterials.In this work,we introduce a novel method for imidacloprid(IMI)pesticide residue detection using the rod-shaped terahertz metamaterial(RSTM)with a composite interface of gold and conductive polymer polyaniline(PANI).The core mechanism of this method relies on the binding of IMI to PANI,which alters the resonance intensity and frequency of the Au-PANI-RSTM.Specifically,the RSTM parameters are determined using computer simulation technology(CST),and the RSTM structure is engraved on the Au-PANI surface using laser direct writing technology.Further characterization using mid-infrared spectroscopy(MIR)and X-ray photoelectron spectroscopy(XPS)techniques reveals that the stable bonding between PANI and IMI is facilitated by hydrogen bonding and covalent bonding.The detection limit of Au-PANI-RSTM deposited with 20 segments for IMI is 0.46 ppm,which complies with the maximum residue limit for IMI stipulated in the Chinese National Standard.
基金supported by the Natural Science Foundation of Anhui Province(2308085QH303)Anhui Provincial Health Research Program(AHWJ2022b113)Basic and Clinical Collaboration Program of Anhui Medical University(2022sfy004)。
文摘The hybridization chain reaction(HCR)is a widely used nucleic acid amplification technique that is essential for gene expression analysis and disease diagnosis.Despite its inherent stability,traditional HCR often suffers from low detection efficiency,which necessitates the use of supplementary molecular technologies to enhance its performance for detecting trace samples.Drawing insights from confinement theory,we have proposed a novel cruciform DNA scaffold-based HCR reaction system(C-HCR).In our approach,the DNA cruciform is assembled with the initiating probes of the HCR reaction through specific binding between adenine-rich and thymine-rich regions.This assembly with derived chains does not interfere with the HCR process.When a target is present,traditional HCR reactions yield long-chain linear products.However,the incorporation of the DNA cruciform in C-HCR leads to the formation of network-like products,which create favorable conditions for efficient molecular collisions and,in turn,promote high detection efficiency within the system.We utilized miR-21 and miR-27a as model targets to validate our design concept.Our results revealed that the miRNA-specific HCR system for miR-21 and miR-27a achieved significant increases in detection efficiency of 27.8%and 50%,respectively,demonstrating the feasibility and versatility of our design.This study offers a new strategy for enzyme-free amplification systems.
