spectroscopy

摘要： Metal-organic frameworks(MOFs) have been widely used in oxygen reduction reaction(ORR) of fuel cells and metal-air batteries, attributed to their unique structures and compositions. Recently, the preparation of transition-metallic single-atom electrocatalysts(TM-SACs) using MOFs as precursors or templates has made great progress. Herein, the development history of SACs prepared based on MOFs and their characterization are overviewed firstly, and then several strategies are summarized for preparing TM-SACs using MOFs and further modification. Finally, the challenges and opportunities confronted by TM-SACs are fully discussed. Consequently, our work can guide the realization of TM-SACs abundant with high activity, high loading and high stability.

摘要： ABSTRACT Aneutronic fusion reactions such as proton-boron fusion could efficiently produce clean energy with quite low neutron doses.However,as a consequence,conventional neutron spectral methods for diagnosing plasma ion temperature would no longer work.Therefore,finding a way to probe the ion temperature in aneutronic fusion plasmas is a crucial task.Here,we present a method to realize ultrafast in situ probing of^(11)B ion temperature for proton-boron fusion by Doppler broadening of the nuclear resonance fluorescence(NRF)emission spectrum.The NRF emission is excited by a collimated,intenseγ-ray beam generated from submicrometer wires irradiated by a recently available petawatt(PW)laser pulse,where theγ-ray beam generation is calculated by three-dimensional particle-in-cell simulation.When the laser power is higher than 1 PW,five NRF signatures of a^(11)B plasma can be clearly identified with high-resolutionγ-ray detectors,as shown by our Geant4 simulations.The correlation between the NRF peak width and^(11)B ion temperature is discussed,and it is found that NRF emission spectroscopy should be sensitive to 11B ion temperatures T_(i)>2.4 keV.This probing method can also be extended to other neutron-free-fusion isotopes,such as^(6)Li and^(15)N.

摘要： Cluster analysis in spectroscopy presents some unique challenges due to the specific data characteristics in spectroscopy,namely,high dimensionality and small sample size.In order to improve cluster analysis outcomes,feature selection can be used to remove redundant or irrelevant features and reduce the dimensionality.However,for cluster analysis,this must be done in an unsupervised manner without the benefit of data labels.This paper presents a novel feature selection approach for cluster analysis,utilizing clusterability metrics to remove features that least contribute to a dataset’s tendency to cluster.Two versions are presented and evaluated:The Hopkins clusterability filter which utilizes the Hopkins test for spatial randomness and the Dip clusterability filter which utilizes the Dip test for unimodality.These new techniques,along with a range of existing filter and wrapper feature selection techniques were evaluated on eleven real-world spectroscopy datasets using internal and external clustering indices.Our newly proposed Hopkins clusterability filter performed the best of the six filter techniques evaluated.However,it was observed that results varied greatly for different techniques depending on the specifics of the dataset and the number of features selected,with significant instability observed for most techniques at low numbers of features.It was identified that the genetic algorithm wrapper technique avoided this instability,performed consistently across all datasets and resulted in better results on average than utilizing the all the features in the spectra.

摘要： Intracavity absorption spectroscopy is a strikingly sensitive technique that has been integrated with a two-wavelength setup to develop a sensor for human breath.Various factors are considered in such a scenario,out of which Relative Intensity Noise(RIN)has been exploited as an important parameter to characterize and calibrate the said setup.During the performance of an electrical based assessment arrangement which has been developed in the laboratory as an alternative to the expensive Agilent setup,the optical amplifier plays a pivotal role in its development and operation,along with other components and their significance.Therefore,the investigation and technical analysis of the amplifier in the system has been explored in detail.The algorithm developed for the automatic measurements of the system has been effectively deployed in terms of the laser’s performance.With this in perspective,a frequency dependent calibration has been pursued in depth with this scheme which enhances the sensor’s efficiency in terms of its sensitivity.In this way,our investigation helps us in a better understanding and implementation perspective of the proposed system,as the outcomes of our analysis adds to the precision and accuracy of the entire system.

摘要： Ionic liquids(ILs) have attracted increasing attention since last few decades due to their high molecular design abilities and wide applications in different fields.In this study,four novel fluorescent isoquinolino [2,1-a]quinoxalin-5-ium ILs were designed and synthesized via a two-step process including a simple dual Schiff’s base formation and a subsequent [RhCp*Cl_(2)]_(2)-catalyzed oxidative C-H activation/annulation reaction.The as-synthesized ILs were extensively characterized using FT-IR,~1 H-NMR,^(13)C-NMR,^(19)F-NMR,HSQC-NMR,HMBC-NMR and HR-MS.Their photophysical properties were determined by steady-state fluorescence spectroscopy.The results demonstrate that all these ILs showed dual or triple emissions,large stokes shift(90 nm) and mechanochromic behaviors.Basing on solvatochromism and titration experiments,it is thought that the emission bands of the ILs are raised from their local excited states,charge transfer states or excited state proton transfer of cations,while the substitute effect of these quinoxaline derived ILs on their stokes shifts is negligible.

摘要： This study focuses on the nature of giant micas occurring at the contact between theÖzvatan(foid-bearing)syenites and the metamorphic basement in Central Anatolia.The studied micas are dark greenish-black in color and crystallized within vein shape like bodies as a narrow lens.The origin and processes responsible for the formation of these independent crystals of the giant micas were investigated by mineralogical,petrographical and geochemical analyses with the use of Confocal Raman Spectroscopy(CRS),Fourier Transform Infrared(FTIR)Spectroscopy,X-Ray Diffraction(XRD),Polarized Energy Dispersive X-Ray Fluorescence Spectrometer(PED-XRF)and Electron Probe Micro Analysis(EPMA).According to XRD,CRS,FTIR and EPMA data,the giant micas are phlogopite.EPMA results reveal that studied mica minerals represent the products of re-equilibrated primary mica characterized by high MgO and FeO and low Al2O3 and TiO2 contents.The trace element concentrations of the giant micas display similar patterns with the upper crust.The giant micas are crystallized within small cubicles from an alkaline magma and their composition is possibly modified by a mixing event between the crust-and mantle-derived magmas and contaminated at varying extent by the basement metamorphic rocks.

摘要： A simple, precise, inexpensive and reproducible spectrophotometric method was investigated for the determination of chromium ion (III) in aqueous media, this method based on the formation of a complex between chromium ion (III) and ninhydrin, a deep greenish-violet colored product in the presence of potassium hydroxide was obtained. The absorption of this product was measured at λmax = 375 nm. The reaction proceeds quantitatively at room temperature. The linear calibration curve was constructed over range of (4.8 × 10-4 - 1.6 × 10-2) mol/L of chromium ions with molar absorptivity of 2.90 × 102 and correlation coefficient R2 = 0.9989. The calculated Sandell’s sensitivity value is 0.179 μg/cm2, the limits of detection (LOD) and the limit of quantification (LOQ) are found to be 3.74 × 10-5 and 1.24 × 10-4 mol/L, respectively. The method was successfully applied for determination of the chromium ion in aqueous solution. The stoichiometry of the reactions was determined molar combining ratio of 1:2 between chromium and ninhydrin.

摘要： Laser-induced breakdown spectroscopy (LIBS) is an atomic emission spectroscopy technique gaining much attention since it was created in 1962[1].In 2021,the 4th Asian Symposium on LIBS (ASLIBS) and the ten-year anniversary of Chinese Symposium on LIBS (CSLIBS) were jointly held in Qingdao,symbolizing the development of the Asian and Chinese LIBS communities into a new stage.Since the initiation of CSLIBS in Qingdao (2011) and ASLIBS in Wuhan[2](2015).

摘要： Major elements such as Fe,Ti,Mg,Al,Ca and Si play very important roles in understanding the origin and evolution of the Moon.Previous maps of these major elements derived from orbital data are based on mosaic images or low-resolution gamma-ray data.The hue variations and gaps among orbital boundaries in the mosaic images are not conducive to geological studies.This paper aims to produce seamless and homogenous distribution maps of major elements using the single-exposure image of the whole lunar disk obtained by China’s high-resolution geostationary satellite,Gaofen-4,with a spatial resolution of500 m.The elemental contents of soil samples returned by Apollo and Luna missions are regarded as ground truth,and are correlated with the reflectance of the sampling sites extracted from Gaofen-4 data.The final distribution maps of these major oxides are generated with the statistical regression model.With these products,the average contents and proportions of the major elements for maria and highlands were estimated and compared.The results showed that Si O2 and Ti O2 have the highest and lowest fractions in mare and highland areas,respectively.Moreover,the relative concentrations of these elements could serve as indicators of geologic processes,e.g.,the obviously asymmetric distributions of Al2 O3,Ca O and Si O2 around Tycho crater may suggest that Tycho crater was formed by an oblique impact from the southwest direction.

摘要： BACKGROUND Liver diseases are associated with the excess formation of advanced glycation end products(AGEs),which induce tissue inflammation and oxidative damage.However,the trend of oxidative marker levels according to the steatosis grade in non-alcoholic fatty liver disease(NAFLD)is unclear.AIM To compare serum AGE levels between participants with NAFLD accordingly to steatosis severity in the baseline ELSA-Brasil population.METHODS In 305 individuals at baseline ELSA-Brasil,NAFLD-associated steatosis was classified by ultrasound hepatic attenuation.The participants were grouped according to the severity of steatosis:mild and moderate/severe pooled.The measurement of serum fluorescent AGE concentrations was based on spectrofluorimetric detection.Serum AGE content and clinical and laboratory characteristics of the participants were compared between groups.The correlation between serum AGE levels and the grade of steatosis was analyzed.Logistic regression analysis was used to investigate the relationship between serum AGE levels and steatosis severity.A P value<0.05 was considered statistically significant.RESULTS According to the steatosis severity spectrum in NAFLD,from mild to moderate/severe,individuals with the most severe steatosis grade had a higher incidence of metabolic syndrome(63%vs 34%,P≤0.001),diabetes mellitus(37%vs 14%,P≤0.001),and high cholesterol levels(51%vs 33%,P<0.001).Moreover,individuals with increasing severity of steatosis presented increasing waist circumference,body mass index,systolic and diastolic blood pressure,fasting blood glucose,glycated hemoglobin,insulin,triglycerides,alanine aminotransferase,gamma-glutamyl transferase,C-reactive protein,and uric acid levels and lower high-density lipoprotein.Higher serum AGE content was present in the moderate/severe group of individuals than in the mild group(P=0.008).In addition,the serum AGE levels were correlated with the steatosis grade in the overall sample(rho=0.146,P=0.010).Logistic regression analysis,after adjusting for confounding variables,showed that subjects with higher serum AGE content had a 4.6-fold increased chance of having moderate or severe steatosis when compared to low levels of serum AGEs.According to the results of the receiver operator characteristic curves analyses(areas under the curve,AUC=0.83),AGEs could be a good marker of steatosis severity in patients with NAFLD and might be a potential biomarker in predicting NAFLD progression,strengthening the involvement of AGE in NAFLD pathogenesis.CONCLUSION NAFLD-associated steatosis was associated with serum AGE levels;therefore,plasmatic fluorescent AGE quantification by spectroscopy could be a promising alternative method to monitor progression from mild to severe NAFLD accordingly to steatosis grade.