In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical sim...In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical simulation model was established to optimize the design of the QTF structure.In the simulation of quartz-enhanced photoacoustic spectroscopy(QEPAS)technology,the maximum stress and the surface charge density of the four-prong QTF demonstrated increases of 11.1-fold and 15.9-fold,respectively,compared to that of the standard two-prong QTF.In the simulation of light-induced thermoelastic spectroscopy(LITES)technology,the surface temperature difference of the four-prong QTF was found to be 11.4 times greater than that of the standard QTF.Experimental results indicated that the C_(2)H_(2)-QEPAS system based on this innovative design improved the signal-to-noise-ratio(SNR)by 4.67 times compared with the standard QTF-based system,and the SNR could increase up to 147.72 times when the four-prong QTF was equipped with its optimal acoustic micro-resonator(AmR).When the average time of the system reached 370 s,the system achieved a MDL as low as 21 ppb.The four-prong QTF-based C_(2)H_(2)-LITES system exhibited a SNR improvement by a factor of 4.52,and a MDL of 96 ppb was obtained when the average time of the system reached 100 s.The theoretical and experimental results effectively demonstrated the superiority of the four-prong QTF in the field of laser spectroscopy sensing.展开更多
Background:Magnetic resonance spectroscopy(MRS)represents a significant advancement in the noninvasive assessment of brain metabolism.MRS can provide valuable metabolic information and facilitate more accurate diagnos...Background:Magnetic resonance spectroscopy(MRS)represents a significant advancement in the noninvasive assessment of brain metabolism.MRS can provide valuable metabolic information and facilitate more accurate diagnoses of intrauterine fetal brain development than was previously possible.To obtain information regarding normal intrauterine fetal brain metabolism and to establish gestational age-specific reference values for normal fetal brain metabolites for subsequent use in MRS,we conducted MRS scans of normal fetal brains during mid-to late-term pregnancies,along with related processing.Methods:In this prospective study,MRS scans were conducted on 109 fetuses,with a total of 54 normal fetal brains enrolled on the basis of specific inclusion and exclusion criteria.We analyzed metabolic ratios,including the sum of N-acetylaspartate(NAA)and total N-acetylaspartate(tNAA),total choline(tCho),inositol(Ins),and total creatine(tCr),in relation to gestational age.Results:Gestational age was significantly correlated with specific metabolic ratios(Ins/tCr:r=-0.75,p<0.0001;tCho/tCr:r=-0.50,p<0.0001),especially tNAA/tCho(tNAA/tCho:r=0.54,p<0.0001)and tNAA/Ins(r=0.56,p<0.0001),providing a baseline for fetal brain metabolic assessment.Linear regression analysis was used to calculate regression lines for fetal brain metabolite ratios.Slopes were tested at p of 0.05.Conclusions:The current findings confirmed a significant correlation between fetal brain metabolites and gestational age,supporting the feasibility of establishing standard values for these metabolites in fetal brain assessment.展开更多
Atmospheric chemistry research and atmospheric measurement techniques have mutually promoted each other and developed rapidly in China in recent years.Cavity-based absorption spectroscopy,which uses a high-finesse cav...Atmospheric chemistry research and atmospheric measurement techniques have mutually promoted each other and developed rapidly in China in recent years.Cavity-based absorption spectroscopy,which uses a high-finesse cavity to achieve very long absorption path-length,thereby achieving ultra-high detection sensitivity,plays an extremely important role in atmospheric chemistry research.Based on the Beer–Lambert law,this technology has the unique advantages of being non-destructive,chemical-free,and highly selective.It does not require any sample preparation and can quantitatively analyze atmospheric trace gases in real time and in situ.In this paper,we review the following:(1)key technological advances in different cavity-based absorption spectroscopy techniques,including cavity ring-down spectroscopy,cavityenhanced absorption spectroscopy,cavity attenuated phase shift spectroscopy,and their extensions;and(2)applications of these techniques in the detection of atmospheric reactive species,such as total peroxy radical,formaldehyde,and reactive nitrogen(e.g.,NOx,HONO,peroxy nitrates,and alkyl nitrates).The review systematically introduces cavity-based absorption spectroscopy techniques and their applications in atmospheric chemistry,which will help promote further communication and cooperation in the fields of laser spectroscopy and atmospheric chemistry.展开更多
Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrate...Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrates.Here we present a SM-SERS scheme that involves simultaneously giant chemical enhancement from WS22D materials,giant electromagnetic enhancement from plasmonic nanogap hot spot,and inhibition of molecular fluorescence influence under near-infrared laser illumination.Remarkably we find Coulomb attraction between analyte and gold nanoparticle can trigger spontaneous formation of molecule-hotspot pairing with high precision,stability and robustness.The scheme has enabled realization of universal,robust,fast,and large-scale uniform SM-SERS detection for three Raman molecules of rhodamine B,rhodamine 6G,and crystal violet with a very low detection limit of 10−16 M and at a very fast spectrum acquisition time of 50 ms.展开更多
In this editorial,we comment on the recent article by Fei et al exploring the field of near-infrared spectroscopy(NIRS)research in schizophrenia from a bibliometrics perspective.In recent years,NIRS has shown unique a...In this editorial,we comment on the recent article by Fei et al exploring the field of near-infrared spectroscopy(NIRS)research in schizophrenia from a bibliometrics perspective.In recent years,NIRS has shown unique advantages in the auxiliary diagnosis of schizophrenia,and the introduction of bibliometrics has provided a macro perspective for research in this field.Despite the opportunities brought about by these technological developments,remaining challenges require multidi-sciplinary approach to devise a reliable and accurate diagnosis system for schizo-phrenia.Nonetheless,NIRS-assisted technology is expected to contribute to the division of methods for early intervention and treatment of schizophrenia.展开更多
In sub nanometer carbon nanotubes,water exhibits unique dynamic characteristics,and in the high-frequency region of the infrared spectrum,where the stretching vibrations of the internal oxygen-hydrogen(O-H)bonds are c...In sub nanometer carbon nanotubes,water exhibits unique dynamic characteristics,and in the high-frequency region of the infrared spectrum,where the stretching vibrations of the internal oxygen-hydrogen(O-H)bonds are closely related to the hydrogen bonds(H-bonds)network between water molecules.Therefore,it is crucial to analyze the relationship between these two aspects.In this paper,the infrared spectrum and motion characteristics of the stretching vibrations of the O-H bonds in one-dimensional confined water(1DCW)and bulk water(BW)in(6,6)single-walled carbon nanotubes(SWNT)are studied by molecular dynamics simulations.The results show that the stretching vibrations of the two O-H bonds in 1DCW exhibit different frequencies in the infrared spectrum,while the O-H bonds in BW display two identical main frequency peaks.Further analysis using the spring oscillator model reveals that the difference in the stretching amplitude of the O-H bonds is the main factor causing the change in vibration frequency,where an increase in stretching amplitude leads to a decrease in spring stiffness and,consequently,a lower vibration frequency.A more in-depth study found that the interaction of H-bonds between water molecules is the fundamental cause of the increased stretching amplitude and decreased vibration frequency of the O-H bonds.Finally,by analyzing the motion trajectory of the H atoms,the dynamic differences between 1DCW and BW are clearly revealed.These findings provide a new perspective for understanding the behavior of water molecules at the nanoscale and are of significant importance in advancing the development of infrared spectroscopy detection technology.展开更多
All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid...All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.展开更多
Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic a...Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic absorption,(2)modulation spectroscopy,and(3)the most widely used Tauc-plot.The excitonic absorption is based on a many-particle theory,which is physically the most correct approach,but requires more stringent crystalline quality and appropriate sample preparation and experimental implementation.The Tauc-plot is based on a single-particle theo⁃ry that neglects the many-electron effects.Modulation spectroscopy analyzes the spectroscopy features in the derivative spectrum,typically,of the reflectance and transmission under an external perturbation.Empirically,the bandgap ener⁃gy derived from the three approaches follow the order of E_(ex)>E_(MS)>E_(TP),where three transition energies are from exci⁃tonic absorption,modulation spectroscopy,and Tauc-plot,respectively.In principle,defining E_(g) as the single-elec⁃tron bandgap,we expect E_(g)>E_(ex),thus,E_(g)>E_(TP).In the literature,E_(TP) is often interpreted as E_(g),which is conceptual⁃ly problematic.However,in many cases,because the excitonic peaks are not readily identifiable,the inconsistency be⁃tween E_(g) and E_(TP) becomes invisible.In this brief review,real world examples are used(1)to illustrate how excitonic absorption features depend sensitively on the sample and measurement conditions;(2)to demonstrate the differences between E_(ex),E_(MS),and E_(TP) when they can be extracted simultaneously for one sample;and(3)to show how the popular⁃ly adopted Tauc-plot could lead to misleading results.Finally,it is pointed out that if the excitonic absorption is not ob⁃servable,the modulation spectroscopy can often yield a more useful and reasonable bandgap than Tauc-plot.展开更多
This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectr...This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectroscopy. It is noted that while different bottle top types photo-oxidize at different rates, all show an appreciable level of oxidation after half a year of exposure to the environment. The oxidation leads to brittleness of the plastic, which leads to fissure formation in bottle tops of little thickness. This leads to fragmentation of the material upon impact, making plastic bottle tops an appreciable source of microplastics.展开更多
Antifungal resistance is the leading cause of antifungal treatment failure in invasive candidiasis.Metabolic rewiring could become a new insight to account for antifungal resistance as to find innovative clinical ther...Antifungal resistance is the leading cause of antifungal treatment failure in invasive candidiasis.Metabolic rewiring could become a new insight to account for antifungal resistance as to find innovative clinical therapies.Here,we show that dynamic surface-enhanced Raman spectroscopy is a promising tool to identify the metabolic differences between fluconazole(Diflucan)-resistant and fluconazole(Diflucan)-sensitive Candida albicans through the signatures of biochemical components and complemented with machine learning algorithms and two-dimensional correlation spectroscopy,an underlying resistance mechanism,that is,the change of purine metabolites induced the resistance of Candida albicans has been clarified yet never reported anywhere.We hope the integrated methodology introduced in this work could be beneficial for the interpretation of cellular regulation,propelling the development of targeted antifungal therapies and diagnostic tools for more efficient management of severe antifungal resistance.展开更多
Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA...Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA)spectroscopy,attenuated total reflection(ATR)spectroscopy and molecular dynamics(MD),we reveal the assembled C≡N at gold nanofilm exhibits a reduced Stark tuning rate(STR)referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au.These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.展开更多
Infrared(IR)spectroscopy,a technique within the realm of molecular vibrational spectroscopy,furnishes distinctive chemical signatures pivotal for both structural analysis and compound identification.A notable challeng...Infrared(IR)spectroscopy,a technique within the realm of molecular vibrational spectroscopy,furnishes distinctive chemical signatures pivotal for both structural analysis and compound identification.A notable challenge emerges from the misalignment between the mid-IR light wavelength range and molecular dimensions,culminating in a constrained absorption cross-section and diminished vibrational absorption coefficients(Supplementary data).展开更多
Objective The national lifetime prevalence of urolithiasis is estimated at 6.6%in Iran.However,reports on the composition of kidney stones have been based on imprecise methods like the chemical analysis.No prior large...Objective The national lifetime prevalence of urolithiasis is estimated at 6.6%in Iran.However,reports on the composition of kidney stones have been based on imprecise methods like the chemical analysis.No prior large-scale study has reported the composition of kidney stones based on the gold-standard methods(X-ray diffraction or infrared spectroscopy)in Iran.This study aimed to provide the composition of kidney stones based on Fourier transform infrared spectroscopy.Methods This is a cross-sectional study assessing urinary stone composition from various cities in Iran at a referral center using infrared spectroscopy from February 2019 to March 2023.Results This study determined the stone composition of 1092 patients from 10 cities in Iran.Overall,the majority of stones were composed of calcium oxalate(n=498;45.6%)and uric acid(UA,n=488;44.7%)followed by cystine(n=49;4.5%)and struvite(n=28;2.6%).Stone composition in Shiraz and Isfahan was roughly similar with a higher percentage of UA stones(53.4%and 53.6%,respectively)while the capital city of Iran(Tehran)had less frequent UA stones(39.9%)with a higher percentage of calcium oxalate stones.The percentage of UA stones increased with age as it was 11.1%in children,42.7%in adults,and 83.3%in geriatric patients(p<0.001).About 29.6%of cystine stones were observed in children.Conclusion The most frequent stone composition among kidney stones in Iran was calcium oxalate and UA stones.This relative frequency of UA stones is considerably higher than many international reports from neighboring as well as distant countries.More cystine stones were observed in children and women.Geriatric patients’stones were mostly composed of UA.展开更多
Frequency-modulated continuous-wave radar enables the non-contact and privacy-preserving recognition of human behavior.However,the accuracy of behavior recognition is directly influenced by the spatial relationship be...Frequency-modulated continuous-wave radar enables the non-contact and privacy-preserving recognition of human behavior.However,the accuracy of behavior recognition is directly influenced by the spatial relationship between human posture and the radar.To address the issue of low accuracy in behavior recognition when the human body is not directly facing the radar,a method combining local outlier factor with Doppler information is proposed for the correction of multi-classifier recognition results.Initially,the information such as distance,velocity,and micro-Doppler spectrogram of the target is obtained using the fast Fourier transform and histogram of oriented gradients-support vector machine methods,followed by preliminary recognition.Subsequently,Platt scaling is employed to transform recognition results into confidence scores,and finally,the Doppler-local outlier factor method is utilized to calibrate the confidence scores,with the highest confidence classifier result considered as the recognition outcome.Experimental results demonstrate that this approach achieves an average recognition accuracy of 96.23%for comprehensive human behavior recognition in various orientations.展开更多
3-Nitro-1,2,4-triazol-5-one(NTO)is a typical high-energy,low-sensitivity explosive,and accurate concentration monitoring is critical for crystallization process control.In this study,a high-precision quantitative anal...3-Nitro-1,2,4-triazol-5-one(NTO)is a typical high-energy,low-sensitivity explosive,and accurate concentration monitoring is critical for crystallization process control.In this study,a high-precision quantitative analytical model for NTO concentration in ethanol solutions was developed by integrating real-time ATR-FTIR spectroscopy with chemometric and machine learning techniques.Dynamic spectral data were obtained by designing multi-concentration gradient heating-cooling cycle experiments,abnormal samples were eliminated using the isolation forest algorithm,and the effects of various preprocessing methods on model performance were systematically evaluated.The results show that partial least squares regression(PLSR)exhibits superior generalization ability compared to other models.Vibrational bands corresponding to C=O and–NO_(2)were identified as key predictors for concentration estimation.This work provides an efficient and reliable solution for real-time concentration monitoring during NTO crystallization and holds significant potential for process analytical applications in energetic material manufacturing.展开更多
Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ra...Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.展开更多
Objective:To investigate the characteristics and significance of near-infrared brain function imaging in patients with depressive disorder after administration of propofol injection.Methods:A total of 28 subjects with...Objective:To investigate the characteristics and significance of near-infrared brain function imaging in patients with depressive disorder after administration of propofol injection.Methods:A total of 28 subjects with depressive disorder diagnosed according to DSM-5 criteria were selected from Xi’an Mental Health Center between January 2022 and January 2025.They were randomly divided into an experimental group(propofol group,n=14)and a control group(intralipid group,n=14)using a random number table.The changes in integral value(IV)and centroid value(CV)of the two patient groups before and after treatment were measured using functional near-infrared spectroscopy(fNIRS)technology.Results:There was no statistically significant difference in HAMD scores between the two groups of patients at 24 h before treatment(P>0.05).Repeated measures analysis of variance showed that both time factor(Ftime=32.237,Ptime<0.001),group factor(Fgroup=47.027,Pgroup<0.001),and their interaction(Finteraction=31.829,Pinteraction<0.001)were statistically significant.The centroid values of the frontal and temporal lobes were consistent at baseline before treatment,with no intra-group changes or inter-group differences at any time point after treatment(P>0.05).The integral values of the frontal and temporal lobes were consistent between the two groups at baseline before treatment,and both showed a time-dependent increase after treatment(Ptime<0.05).However,the increase in the experimental group was significantly greater than that in the control group(Pgroup<0.05),with a significant interaction effect(Pinteraction<0.05).Conclusion:fNIRS detected specific acute hemodynamic changes in the prefrontal and temporal regions of patients with depressive disorder after propofol intervention.These changes may be related to the mechanism of action of propofol.However,this study did not confirm a direct linear correlation between changes in integral/centroid values and the degree of clinical improvement in depressive symptoms.Propofol intervention combined with deep anesthesia rapidly improved depressive symptoms and was accompanied by enhanced hemodynamic activity in the prefrontal/temporal regions,though its specificity requires further validation.展开更多
Electrochemical impedance spectroscopy(EIS)was used to examine the electrical properties of metakaolin(MK)cement-based materials at elevated temperatures.We utilized a new equivalent circuit to investigate the EIS res...Electrochemical impedance spectroscopy(EIS)was used to examine the electrical properties of metakaolin(MK)cement-based materials at elevated temperatures.We utilized a new equivalent circuit to investigate the EIS results of cementitious materials blended with MK at these temperatures.A new evaluation method to high temperature damage is proposed.The findings show that both elevated temperatures and MK contents in cement mortar can impact the impedance spectra’s form properties.However,the residual compressive strength of the MK-blended cementitious material at elevated temperatures does not improve with the addition of MK.A quantitative relationship between the electrochemical parameters of the new equivalent circuit and the residual compressive strength is determined.The degree of high-temperature damage to cementitious materials can be evaluated based on these electrochemical parameters,providing a new approach for evaluating the high-temperature damage of MK-blend cementitious materials.展开更多
We present a comprehensive electron momentum spectroscopy study on the electronic structure of trifluorobromomethane.The binding energy spectrum and electron momentum profiles of the entire outer-valence orbitals and ...We present a comprehensive electron momentum spectroscopy study on the electronic structure of trifluorobromomethane.The binding energy spectrum and electron momentum profiles of the entire outer-valence orbitals and the first inner-valence orbital along with several shake-up states were measured by using a high-sensitivity(e,2e)apparatus at an electron impact energy of 1213 eV.Theoretical calculations employing the density functional theory with B3LYP hybrid functional and the symmetry-adapted cluster configuration-interaction method were performed to interpret the experimental results.Important effects of electron correlations in the initial neutral and final ionic states on the electron momentum profiles have been observed.展开更多
Angle-resolved photoemission spectroscopy(ARPES)has become a cornerstone technique for elucidating the electronic structures of emergent quantum materials.Among these,kagome materials—distinguished by their two-dimen...Angle-resolved photoemission spectroscopy(ARPES)has become a cornerstone technique for elucidating the electronic structures of emergent quantum materials.Among these,kagome materials—distinguished by their two-dimensional lattice of corner-sharing triangles—provide a fertile ground for investigating exotic quantum phenomena,driven by geometric frustration,electronic correlation,and topology.In this review,we present an overview of recent ARPES studies on transition-metal kagome materials.We first outline the fundamental features of their electronic structures,including van Hove singularities,Dirac points,and flat bands,and discuss the novel quantum states that arise from many-body interactions within the kagome lattice.We then highlight key ARPES investigations into these unique electronic structures,detailing their manifestation and associated quantum states in representative kagome materials.Finally,we offer a forward-looking perspective on the potential of ARPES to uncover new quantum phenomena and its broader implications for the study of underlying physics in kagome materials.展开更多
基金supports from the National Natural Science Foundation of China(Grant Nos.62335006,62022032,62275065,and 62405078)Key Laboratory of Opto-Electronic Information Acquisition and Manipulation(Anhui University),Ministry of Education(Grant No.OEIAM202202)+2 种基金Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2023011)China Postdoctoral Science Foundation(Grant No.2024M764172)Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23144).
文摘In this paper,a novel four-prong quartz tuning fork(QTF)was designed with enlarged deformation area,large prong gap,and low resonant frequency to improve its performance in laser spectroscopy sensing.A theoretical simulation model was established to optimize the design of the QTF structure.In the simulation of quartz-enhanced photoacoustic spectroscopy(QEPAS)technology,the maximum stress and the surface charge density of the four-prong QTF demonstrated increases of 11.1-fold and 15.9-fold,respectively,compared to that of the standard two-prong QTF.In the simulation of light-induced thermoelastic spectroscopy(LITES)technology,the surface temperature difference of the four-prong QTF was found to be 11.4 times greater than that of the standard QTF.Experimental results indicated that the C_(2)H_(2)-QEPAS system based on this innovative design improved the signal-to-noise-ratio(SNR)by 4.67 times compared with the standard QTF-based system,and the SNR could increase up to 147.72 times when the four-prong QTF was equipped with its optimal acoustic micro-resonator(AmR).When the average time of the system reached 370 s,the system achieved a MDL as low as 21 ppb.The four-prong QTF-based C_(2)H_(2)-LITES system exhibited a SNR improvement by a factor of 4.52,and a MDL of 96 ppb was obtained when the average time of the system reached 100 s.The theoretical and experimental results effectively demonstrated the superiority of the four-prong QTF in the field of laser spectroscopy sensing.
基金supported by China Society for Maternal and Child Health Research(Gant/Award Number:2023CAMCHS003A17).
文摘Background:Magnetic resonance spectroscopy(MRS)represents a significant advancement in the noninvasive assessment of brain metabolism.MRS can provide valuable metabolic information and facilitate more accurate diagnoses of intrauterine fetal brain development than was previously possible.To obtain information regarding normal intrauterine fetal brain metabolism and to establish gestational age-specific reference values for normal fetal brain metabolites for subsequent use in MRS,we conducted MRS scans of normal fetal brains during mid-to late-term pregnancies,along with related processing.Methods:In this prospective study,MRS scans were conducted on 109 fetuses,with a total of 54 normal fetal brains enrolled on the basis of specific inclusion and exclusion criteria.We analyzed metabolic ratios,including the sum of N-acetylaspartate(NAA)and total N-acetylaspartate(tNAA),total choline(tCho),inositol(Ins),and total creatine(tCr),in relation to gestational age.Results:Gestational age was significantly correlated with specific metabolic ratios(Ins/tCr:r=-0.75,p<0.0001;tCho/tCr:r=-0.50,p<0.0001),especially tNAA/tCho(tNAA/tCho:r=0.54,p<0.0001)and tNAA/Ins(r=0.56,p<0.0001),providing a baseline for fetal brain metabolic assessment.Linear regression analysis was used to calculate regression lines for fetal brain metabolite ratios.Slopes were tested at p of 0.05.Conclusions:The current findings confirmed a significant correlation between fetal brain metabolites and gestational age,supporting the feasibility of establishing standard values for these metabolites in fetal brain assessment.
基金supported by the National Natural Science Foundation of China(Grant Nos.U21A2028,42022051,62275250,42030609,41627810,91644107,and 91544228).
文摘Atmospheric chemistry research and atmospheric measurement techniques have mutually promoted each other and developed rapidly in China in recent years.Cavity-based absorption spectroscopy,which uses a high-finesse cavity to achieve very long absorption path-length,thereby achieving ultra-high detection sensitivity,plays an extremely important role in atmospheric chemistry research.Based on the Beer–Lambert law,this technology has the unique advantages of being non-destructive,chemical-free,and highly selective.It does not require any sample preparation and can quantitatively analyze atmospheric trace gases in real time and in situ.In this paper,we review the following:(1)key technological advances in different cavity-based absorption spectroscopy techniques,including cavity ring-down spectroscopy,cavityenhanced absorption spectroscopy,cavity attenuated phase shift spectroscopy,and their extensions;and(2)applications of these techniques in the detection of atmospheric reactive species,such as total peroxy radical,formaldehyde,and reactive nitrogen(e.g.,NOx,HONO,peroxy nitrates,and alkyl nitrates).The review systematically introduces cavity-based absorption spectroscopy techniques and their applications in atmospheric chemistry,which will help promote further communication and cooperation in the fields of laser spectroscopy and atmospheric chemistry.
基金financial support from Science and Technology Project of Guangdong(2020B010190001)National Natural Science Foundation(12434016).
文摘Raman spectroscopy offers a great power to detect,analyze and identify molecules,and monitor their temporal dynamics and evolution when combined with single-molecule surface-enhanced Raman scattering(SM-SERS)substrates.Here we present a SM-SERS scheme that involves simultaneously giant chemical enhancement from WS22D materials,giant electromagnetic enhancement from plasmonic nanogap hot spot,and inhibition of molecular fluorescence influence under near-infrared laser illumination.Remarkably we find Coulomb attraction between analyte and gold nanoparticle can trigger spontaneous formation of molecule-hotspot pairing with high precision,stability and robustness.The scheme has enabled realization of universal,robust,fast,and large-scale uniform SM-SERS detection for three Raman molecules of rhodamine B,rhodamine 6G,and crystal violet with a very low detection limit of 10−16 M and at a very fast spectrum acquisition time of 50 ms.
文摘In this editorial,we comment on the recent article by Fei et al exploring the field of near-infrared spectroscopy(NIRS)research in schizophrenia from a bibliometrics perspective.In recent years,NIRS has shown unique advantages in the auxiliary diagnosis of schizophrenia,and the introduction of bibliometrics has provided a macro perspective for research in this field.Despite the opportunities brought about by these technological developments,remaining challenges require multidi-sciplinary approach to devise a reliable and accurate diagnosis system for schizo-phrenia.Nonetheless,NIRS-assisted technology is expected to contribute to the division of methods for early intervention and treatment of schizophrenia.
基金Supported by the Natural Science Foundation of China(51705326,52075339)。
文摘In sub nanometer carbon nanotubes,water exhibits unique dynamic characteristics,and in the high-frequency region of the infrared spectrum,where the stretching vibrations of the internal oxygen-hydrogen(O-H)bonds are closely related to the hydrogen bonds(H-bonds)network between water molecules.Therefore,it is crucial to analyze the relationship between these two aspects.In this paper,the infrared spectrum and motion characteristics of the stretching vibrations of the O-H bonds in one-dimensional confined water(1DCW)and bulk water(BW)in(6,6)single-walled carbon nanotubes(SWNT)are studied by molecular dynamics simulations.The results show that the stretching vibrations of the two O-H bonds in 1DCW exhibit different frequencies in the infrared spectrum,while the O-H bonds in BW display two identical main frequency peaks.Further analysis using the spring oscillator model reveals that the difference in the stretching amplitude of the O-H bonds is the main factor causing the change in vibration frequency,where an increase in stretching amplitude leads to a decrease in spring stiffness and,consequently,a lower vibration frequency.A more in-depth study found that the interaction of H-bonds between water molecules is the fundamental cause of the increased stretching amplitude and decreased vibration frequency of the O-H bonds.Finally,by analyzing the motion trajectory of the H atoms,the dynamic differences between 1DCW and BW are clearly revealed.These findings provide a new perspective for understanding the behavior of water molecules at the nanoscale and are of significant importance in advancing the development of infrared spectroscopy detection technology.
基金supported by the Beijing Natural Science Foundation(Z200011,L233004)the National Key Research and Development Program(2021YFB2500300)+3 种基金the National Natural Science Foundation of China(52394170,52394171,22109011,22393900,and 22108151)the Tsinghua-Jiangyin Innovation Special Fund(TJISF)(2022JYTH0101)the S&T Program of Hebei(22344402D)the Tsinghua University Initiative Scientific Research Program.
文摘All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.
基金Supported by Bissell Distinguished Professor Endowment Fund at UNC-Charlotte。
文摘Although there are numerous optical spectroscopy techniques and methods that have been used to extract the fundamental bandgap of a semiconductor,most of them belong to one of these three approaches:(1)the excitonic absorption,(2)modulation spectroscopy,and(3)the most widely used Tauc-plot.The excitonic absorption is based on a many-particle theory,which is physically the most correct approach,but requires more stringent crystalline quality and appropriate sample preparation and experimental implementation.The Tauc-plot is based on a single-particle theo⁃ry that neglects the many-electron effects.Modulation spectroscopy analyzes the spectroscopy features in the derivative spectrum,typically,of the reflectance and transmission under an external perturbation.Empirically,the bandgap ener⁃gy derived from the three approaches follow the order of E_(ex)>E_(MS)>E_(TP),where three transition energies are from exci⁃tonic absorption,modulation spectroscopy,and Tauc-plot,respectively.In principle,defining E_(g) as the single-elec⁃tron bandgap,we expect E_(g)>E_(ex),thus,E_(g)>E_(TP).In the literature,E_(TP) is often interpreted as E_(g),which is conceptual⁃ly problematic.However,in many cases,because the excitonic peaks are not readily identifiable,the inconsistency be⁃tween E_(g) and E_(TP) becomes invisible.In this brief review,real world examples are used(1)to illustrate how excitonic absorption features depend sensitively on the sample and measurement conditions;(2)to demonstrate the differences between E_(ex),E_(MS),and E_(TP) when they can be extracted simultaneously for one sample;and(3)to show how the popular⁃ly adopted Tauc-plot could lead to misleading results.Finally,it is pointed out that if the excitonic absorption is not ob⁃servable,the modulation spectroscopy can often yield a more useful and reasonable bandgap than Tauc-plot.
文摘This communication looks at the photo-oxidation of polythene and polypropylene plastic bottle tops that are placed on soil in a hot arid environment. The degree of oxidation of the plastic is monitored by FT-IR spectroscopy. It is noted that while different bottle top types photo-oxidize at different rates, all show an appreciable level of oxidation after half a year of exposure to the environment. The oxidation leads to brittleness of the plastic, which leads to fissure formation in bottle tops of little thickness. This leads to fragmentation of the material upon impact, making plastic bottle tops an appreciable source of microplastics.
基金supported by grants from the National Natural Science Foundation of China(Nos.22074015 and 82074428)Youth Talent Cultivation Initiation Fund of Zhongda Hospital,Southeast University(No.CZXM-GSP-RC110)to Hao Li+1 种基金Evidence-Based Capacity Building for TCM Specialty Therapies for Skin Diseases of National Administration of TCMInnovative Team Projects of Shanghai Municipal Commission of Health(No.2022CX011)to Fulun Li.
文摘Antifungal resistance is the leading cause of antifungal treatment failure in invasive candidiasis.Metabolic rewiring could become a new insight to account for antifungal resistance as to find innovative clinical therapies.Here,we show that dynamic surface-enhanced Raman spectroscopy is a promising tool to identify the metabolic differences between fluconazole(Diflucan)-resistant and fluconazole(Diflucan)-sensitive Candida albicans through the signatures of biochemical components and complemented with machine learning algorithms and two-dimensional correlation spectroscopy,an underlying resistance mechanism,that is,the change of purine metabolites induced the resistance of Candida albicans has been clarified yet never reported anywhere.We hope the integrated methodology introduced in this work could be beneficial for the interpretation of cellular regulation,propelling the development of targeted antifungal therapies and diagnostic tools for more efficient management of severe antifungal resistance.
基金The National Key R&D Program of China(No.2022YFE0113000)the National Science Fund for Distinguished Young Scholars(No.22025406)+1 种基金the National Natural Science Foundation of China(Nos.22074138,12174457)the Youth Innovation Promotion Association of CAS(No.2020233)for financial support。
文摘Revealing the factors that affect the vibrational frequency of Stark probe at interface is a pre-requirement for evaluating the absolute interfacial electric field.Here using surface-enhanced infrared absorption(SEIRA)spectroscopy,attenuated total reflection(ATR)spectroscopy and molecular dynamics(MD),we reveal the assembled C≡N at gold nanofilm exhibits a reduced Stark tuning rate(STR)referring to the vibrational frequency shift in response to electric field comparing with the bulk which was regulated by the electron transfer between S and Au.These findings lead to a deeper understanding of the vibrational Stark effect at the interface and provide guidance for improving the interface electric field theory.
基金supported by National Natural Science Foundation of China(Grant No.:32301161)the Natural Scientific Foundation of Hunan Province,China(Grant No.:2023JJ60052)+3 种基金the Scientific Research Project of Hunan Provincial Health Commission,China(Grant No.:202112062218,20190161)the Scientific Research Project of Hunan Provincial Department of Education,China(Grant No.:22B0455)the Clinical“4310”Project of the University of South China,China(Grant No.:20224310NHYCG02)the Doctoral Scientific Research Foundation of University of South China,China(Grant No.:200XQD042).
文摘Infrared(IR)spectroscopy,a technique within the realm of molecular vibrational spectroscopy,furnishes distinctive chemical signatures pivotal for both structural analysis and compound identification.A notable challenge emerges from the misalignment between the mid-IR light wavelength range and molecular dimensions,culminating in a constrained absorption cross-section and diminished vibrational absorption coefficients(Supplementary data).
文摘Objective The national lifetime prevalence of urolithiasis is estimated at 6.6%in Iran.However,reports on the composition of kidney stones have been based on imprecise methods like the chemical analysis.No prior large-scale study has reported the composition of kidney stones based on the gold-standard methods(X-ray diffraction or infrared spectroscopy)in Iran.This study aimed to provide the composition of kidney stones based on Fourier transform infrared spectroscopy.Methods This is a cross-sectional study assessing urinary stone composition from various cities in Iran at a referral center using infrared spectroscopy from February 2019 to March 2023.Results This study determined the stone composition of 1092 patients from 10 cities in Iran.Overall,the majority of stones were composed of calcium oxalate(n=498;45.6%)and uric acid(UA,n=488;44.7%)followed by cystine(n=49;4.5%)and struvite(n=28;2.6%).Stone composition in Shiraz and Isfahan was roughly similar with a higher percentage of UA stones(53.4%and 53.6%,respectively)while the capital city of Iran(Tehran)had less frequent UA stones(39.9%)with a higher percentage of calcium oxalate stones.The percentage of UA stones increased with age as it was 11.1%in children,42.7%in adults,and 83.3%in geriatric patients(p<0.001).About 29.6%of cystine stones were observed in children.Conclusion The most frequent stone composition among kidney stones in Iran was calcium oxalate and UA stones.This relative frequency of UA stones is considerably higher than many international reports from neighboring as well as distant countries.More cystine stones were observed in children and women.Geriatric patients’stones were mostly composed of UA.
基金the National Key Research and Development Program of China(No.2022YFC3601400)。
文摘Frequency-modulated continuous-wave radar enables the non-contact and privacy-preserving recognition of human behavior.However,the accuracy of behavior recognition is directly influenced by the spatial relationship between human posture and the radar.To address the issue of low accuracy in behavior recognition when the human body is not directly facing the radar,a method combining local outlier factor with Doppler information is proposed for the correction of multi-classifier recognition results.Initially,the information such as distance,velocity,and micro-Doppler spectrogram of the target is obtained using the fast Fourier transform and histogram of oriented gradients-support vector machine methods,followed by preliminary recognition.Subsequently,Platt scaling is employed to transform recognition results into confidence scores,and finally,the Doppler-local outlier factor method is utilized to calibrate the confidence scores,with the highest confidence classifier result considered as the recognition outcome.Experimental results demonstrate that this approach achieves an average recognition accuracy of 96.23%for comprehensive human behavior recognition in various orientations.
基金supported by the Aeronautical Science Foundation of China(Grant No.20230018072011)。
文摘3-Nitro-1,2,4-triazol-5-one(NTO)is a typical high-energy,low-sensitivity explosive,and accurate concentration monitoring is critical for crystallization process control.In this study,a high-precision quantitative analytical model for NTO concentration in ethanol solutions was developed by integrating real-time ATR-FTIR spectroscopy with chemometric and machine learning techniques.Dynamic spectral data were obtained by designing multi-concentration gradient heating-cooling cycle experiments,abnormal samples were eliminated using the isolation forest algorithm,and the effects of various preprocessing methods on model performance were systematically evaluated.The results show that partial least squares regression(PLSR)exhibits superior generalization ability compared to other models.Vibrational bands corresponding to C=O and–NO_(2)were identified as key predictors for concentration estimation.This work provides an efficient and reliable solution for real-time concentration monitoring during NTO crystallization and holds significant potential for process analytical applications in energetic material manufacturing.
基金supported by the Vinnova(project number 2020-03778)supported by the Swedish Research Council(Vetenskapsradet,project number 2021-04157).
文摘Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.
基金A Randomized Single-Blind Controlled Trial of Propofol Injection for Depressive Disorder,Xi’an Municipal Science and Technology Bureau(Project No.:22YXYJ0035)。
文摘Objective:To investigate the characteristics and significance of near-infrared brain function imaging in patients with depressive disorder after administration of propofol injection.Methods:A total of 28 subjects with depressive disorder diagnosed according to DSM-5 criteria were selected from Xi’an Mental Health Center between January 2022 and January 2025.They were randomly divided into an experimental group(propofol group,n=14)and a control group(intralipid group,n=14)using a random number table.The changes in integral value(IV)and centroid value(CV)of the two patient groups before and after treatment were measured using functional near-infrared spectroscopy(fNIRS)technology.Results:There was no statistically significant difference in HAMD scores between the two groups of patients at 24 h before treatment(P>0.05).Repeated measures analysis of variance showed that both time factor(Ftime=32.237,Ptime<0.001),group factor(Fgroup=47.027,Pgroup<0.001),and their interaction(Finteraction=31.829,Pinteraction<0.001)were statistically significant.The centroid values of the frontal and temporal lobes were consistent at baseline before treatment,with no intra-group changes or inter-group differences at any time point after treatment(P>0.05).The integral values of the frontal and temporal lobes were consistent between the two groups at baseline before treatment,and both showed a time-dependent increase after treatment(Ptime<0.05).However,the increase in the experimental group was significantly greater than that in the control group(Pgroup<0.05),with a significant interaction effect(Pinteraction<0.05).Conclusion:fNIRS detected specific acute hemodynamic changes in the prefrontal and temporal regions of patients with depressive disorder after propofol intervention.These changes may be related to the mechanism of action of propofol.However,this study did not confirm a direct linear correlation between changes in integral/centroid values and the degree of clinical improvement in depressive symptoms.Propofol intervention combined with deep anesthesia rapidly improved depressive symptoms and was accompanied by enhanced hemodynamic activity in the prefrontal/temporal regions,though its specificity requires further validation.
基金Funded by the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2024QN05023)High Level Talent Research Launch Foundation of Inner Mongolia University(No.10000-22311201/008)。
文摘Electrochemical impedance spectroscopy(EIS)was used to examine the electrical properties of metakaolin(MK)cement-based materials at elevated temperatures.We utilized a new equivalent circuit to investigate the EIS results of cementitious materials blended with MK at these temperatures.A new evaluation method to high temperature damage is proposed.The findings show that both elevated temperatures and MK contents in cement mortar can impact the impedance spectra’s form properties.However,the residual compressive strength of the MK-blended cementitious material at elevated temperatures does not improve with the addition of MK.A quantitative relationship between the electrochemical parameters of the new equivalent circuit and the residual compressive strength is determined.The degree of high-temperature damage to cementitious materials can be evaluated based on these electrochemical parameters,providing a new approach for evaluating the high-temperature damage of MK-blend cementitious materials.
基金Project supported by the National Natural Science Foundation of China(Grant No.12127804).
文摘We present a comprehensive electron momentum spectroscopy study on the electronic structure of trifluorobromomethane.The binding energy spectrum and electron momentum profiles of the entire outer-valence orbitals and the first inner-valence orbital along with several shake-up states were measured by using a high-sensitivity(e,2e)apparatus at an electron impact energy of 1213 eV.Theoretical calculations employing the density functional theory with B3LYP hybrid functional and the symmetry-adapted cluster configuration-interaction method were performed to interpret the experimental results.Important effects of electron correlations in the initial neutral and final ionic states on the electron momentum profiles have been observed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12488201,12074411,12374066,12374154,and 12494593)the National Key Research and Development Program of China(Grant No.2022YFA1403900,2021YFA1401800,2022YFA1604200,2023YFA1406002,2024YFA1408301,and 2024YFA1400026)+3 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant Nos.XDB25000000 and XDB33000000)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301800)the Youth Innovation Promotion Association of CAS(Grant No.Y2021006)Synergetic Extreme Condition User Facility(SECUF).
文摘Angle-resolved photoemission spectroscopy(ARPES)has become a cornerstone technique for elucidating the electronic structures of emergent quantum materials.Among these,kagome materials—distinguished by their two-dimensional lattice of corner-sharing triangles—provide a fertile ground for investigating exotic quantum phenomena,driven by geometric frustration,electronic correlation,and topology.In this review,we present an overview of recent ARPES studies on transition-metal kagome materials.We first outline the fundamental features of their electronic structures,including van Hove singularities,Dirac points,and flat bands,and discuss the novel quantum states that arise from many-body interactions within the kagome lattice.We then highlight key ARPES investigations into these unique electronic structures,detailing their manifestation and associated quantum states in representative kagome materials.Finally,we offer a forward-looking perspective on the potential of ARPES to uncover new quantum phenomena and its broader implications for the study of underlying physics in kagome materials.
