A novel method for the determination of vitamin C（Vc） is proposed in this article. After the reaction with Folin-Ciocalteau reagent at ambient temperature, Vc solution was scanned at 750--1100 nm, and its first-orde...A novel method for the determination of vitamin C（Vc） is proposed in this article. After the reaction with Folin-Ciocalteau reagent at ambient temperature, Vc solution was scanned at 750--1100 nm, and its first-order derivative spectrum were obtained from the original spectrum. The values of derivative selected at 995 nm were used for determination. It was proved that Vc could quickly react with Folin-Ciocalteau reagent within 5 min and the product was quite stable for a long time. The conditions required for this method is not very complicated, its precision and accuracy are similar to those of the iodometric titration described in Chinese Pharmacopoeia, and the limit of detection is 0.312 μg/mL. The determination of the results of vitamin C tablet, pill, and injection demonstrates that this method has wide pharmaceutical applications.展开更多
The rovibrational spectra of thioanisole(TA)and its halogenated derivatives,3-fluorothioanisole(3FTA)and 3-chlorothioanisole(3ClTA),were measured using synchrotron-based Fourier transform infrared spectroscopy(FTIR)at...The rovibrational spectra of thioanisole(TA)and its halogenated derivatives,3-fluorothioanisole(3FTA)and 3-chlorothioanisole(3ClTA),were measured using synchrotron-based Fourier transform infrared spectroscopy(FTIR)at the Canadian Light Source.Combined with density functional theory calculations,the stable structures and vibrational modes of TA,3FTA,and 3ClTA in their vibrational states were analyzed.The theoretical vibrational mode frequencies were corrected by simulating the rotational structure of a vibrational band.The contributions of the cis-and trans-isomers of 3FTA and 3ClTA to the FTIR spectra at 298 K were estimated using the Boltzmann distribution,revealing their coexistence in the experimental spectra.The results indicate that both fluorine and chlorine substitution significantly affect the vibrational modes,particularly in the benzene ring.Compared to TA,the FTIR spectra of 3FTA and 3ClTA show changes in the frequencies and intensities of some vibrational modes,with halogen substitution causing specific modes to shift to higher wavenumbers.A comparison of the FTIR spectra of TA,3FTA,and 3ClTA highlights the influence of halogen substitution on vibrational properties,emphasizing how the type and position of the substituent affect frequency shifts and spectral intensities.These findings provide deeper insights into how halogenation alters vibrational spectra,which is crucial for further spectral analysis and molecular structure determination.展开更多
A biologically active antibacterial reagent, 2-amino-6-hydroxy-4-（4-N, N-dimethylaminophenyl）-pyr- imidine-5-carbonitrile （AHDMAPPC）, was synthesized. It was employed to investigate the binding in- teraction with ...A biologically active antibacterial reagent, 2-amino-6-hydroxy-4-（4-N, N-dimethylaminophenyl）-pyr- imidine-5-carbonitrile （AHDMAPPC）, was synthesized. It was employed to investigate the binding in- teraction with the bovine serum albumin （BSA） in detail using different spectroscopic methods. It ex- hibited antibacterial activity against Escherichia cali and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites （n ≈ 1） were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change （AH）, free energy （AG） and entropy change （AS） for the reaction were calculated to be 15.15 kJ/mol, -36.11 kJ/mol and 51.26J/mol K according to van＇t Hoff equation, respectively. The results indicated that the reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Forster＇s theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV-visible, synchronous fluorescence, circular dichroism （CD） and three-dimensional fluorescence spectra. All these results in- dicated that AHDMAPPC can bind to BSA and be effectively transported and eliminated in the body. It can be a useful guideline for further drug design.展开更多
Azole derivatives such as 2-mercaptobenzothiazole(MBT) and 2-mercaptobenzimidazole(MBI) were introduced as corrosion inhibitors into the interlayer space of sodium montmorillonite clay(Na+-MMT). The corrosion protecti...Azole derivatives such as 2-mercaptobenzothiazole(MBT) and 2-mercaptobenzimidazole(MBI) were introduced as corrosion inhibitors into the interlayer space of sodium montmorillonite clay(Na+-MMT). The corrosion protection behavior of mild steel in solutions containing MBT, MBI, MMT + MBT, MMT + MBI, Na^+-MMT, and NaCl(3.5 wt%) was evaluated using polarization and electrochemical impedance spectroscopy(EIS). Also, the release of penetrated species into the medium from the clay nanocarriers was evaluated using ultraviolet-visible(UV-Vis) spectroscopy. Small-angle X-ray scattering(SAXS) confirmed the insertion of MBT and MBI into the inner space of the clay layers and the interaction between two organic and inorganic phases. Scanning electron microscopy(SEM) was used to assess the morphology of the surface of the steel samples after the samples had been immersed for 24 h in the extraction solution. The corrosion protection in the solutions with clay nanocarriers containing MBT and MBI was better than that in solutions without MMT. The UV-Vis results showed that the release of MBI species from Na+-MMT nanocarriers in neutral pH was far lower than that of MBT species.展开更多
In order to deal with the unclear absorption peak caused by the absorption peak overlap of traditional Chinese medicine(TCM)and other mixtures,a method of three unsupervised clustering algorithms as K-means,K-medoids ...In order to deal with the unclear absorption peak caused by the absorption peak overlap of traditional Chinese medicine(TCM)and other mixtures,a method of three unsupervised clustering algorithms as K-means,K-medoids and Fuzzy C-means(FCM)combined with the first derivative characteristics of terahertz absorption spectrum,is proposed to perform the terahertz spectra clustering of Sanchi and other three kinds of TCM compared with their easily-confused products(ECPs).These three unsupervised clustering methods complement the scope of the supervised learning classification method.The first derivative of the spectrum could amplify the difference in the absorption coefficient with different substances,so that the obvious absorption peak can be revealed.Experiments shows that these three clustering algorithms can achieve good results by combining the origin absorption coefficient with its first-order derivative as the characteristic data,and among which K-means does the best with the accuracy of95.32%.Compared with pure absorption coefficient data clustering,the accuracy in this study has been significantly improved,especially for the non-absorption-peak TCM classification.And the accuracy of K-means algorithm is improved by5.38%.Besides,clustering algorithms in this study have strong anti-interference ability to the error data.展开更多
Fourier transform infrared （FTIR） spectroscopy was used to study diseased leaves in broad bean. Results showed that the infrared spectra of different broad bean diseased leaves were similar, which were mainly made u...Fourier transform infrared （FTIR） spectroscopy was used to study diseased leaves in broad bean. Results showed that the infrared spectra of different broad bean diseased leaves were similar, which were mainly made up of the vibrational absorption bands of protein,lipid and polysaccharide.There were minor differences in-cluding the spectral peak position, peak shape and the absorption intensity in the range of 1 800-1 300 cm-1. There were obvious differences among their second derivative spectra in the range of 1 800-1 300 cm-1. After the procedure of the Fourier self-deconvolution and curve fitting of health bean leaves and broad bean diseased leaves in the range of 1 700-1 500 cm-1, three sub-peaks were obtained at 1 550 cm-1 （protein amide Ⅱ band）, 1 605 cm-1 （lignin） and 1 650 cm-1 （protein amide I band）.The ratios of relative areas of the bands of amide Ⅱ, lignin, and amide I were 38.86%, 28.68% and 32.47% in the spectra of healthy leaves, respec-tively. It was distinguished from the diseased leaves （chocolate spot leaf： 15.42%, 42.98% and 41.61%, ring spot leaf：32.39%, 35.63% and 31.98%, rust leaf： 13.97%, 46.40% and 39.65%, yel owing leaf curl disease leaf： 24.01%,36.55% and 39.44%）. For sub-peak area ratios （A1 563/A1 605, A1 650/A1 605 and A1 563/A1 654）, those of four kinds of diseased leaves were smal er than that of healthy leaves, and there were also differences among four kinds of diseased leaves. The results proved that FTIR combining with curve fitting might be a potential y useful tool for detecting different kinds of broad bean diseases.展开更多
Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved e...Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved electron energy-loss spectroscopy(EELS) analysis. The ceramics were pyrolyzed at1000℃ followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200℃ and dominate at 1500℃. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400℃. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCxand Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400℃. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCxlayers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.展开更多
At present,two-dimensional(2D)materials have shown great application potential in numerous fields based on their physical chemical and electronic properties.Raman spectroscopy and de-rivative techniques are effective ...At present,two-dimensional(2D)materials have shown great application potential in numerous fields based on their physical chemical and electronic properties.Raman spectroscopy and de-rivative techniques are effective tools for characterizing 2D materials.Raman spectroscopy conveys lots of knowledge on 2D materials,including layer number,doping type,strain and interlayer coupling.This review summarized advanced applications of Raman spectroscopy in 2D materials.The challenges and possible applied directions of Raman spectroscopy to 2D materials are discussed in detail.展开更多
In this study,a convenient method using multi-step infrared spectroscopy,including Fourier transform infrared spectroscopy（FT-IR）,second derivative infrared spectroscopy（SD-IR） and two-dimensional correlation infr...In this study,a convenient method using multi-step infrared spectroscopy,including Fourier transform infrared spectroscopy（FT-IR）,second derivative infrared spectroscopy（SD-IR） and two-dimensional correlation infrared spectroscopy（2DCOS-IR）,was employed to analyze and discriminate ten marine sponges from two classes collected from the Xisha Islands in the South China Sea.Each sponge had an exclusive macroscopic fingerprint.From the IR spectra,it was noted that the main ingredient of calcareous sponges was calcium carbonate,but that of demosponges was proteins.For sponges from the same genus or having highly similar chemical profile（IR spectral profile）,SD-IR and 2DCOS-IR were applied to successfully reveal the tiny differences.It was demonstrated that the multi-step infrared spectroscopy was a feasible and objective approach for marine sponge identification.展开更多
Coupled with partial least squares(PLS),near infrared(NIR)spectroscopy was applied to develop a fast and nondestructive method to identify the production date of Rizhao green tea aiming at the deficiencies of the exis...Coupled with partial least squares(PLS),near infrared(NIR)spectroscopy was applied to develop a fast and nondestructive method to identify the production date of Rizhao green tea aiming at the deficiencies of the existing methods.In the modeling process,the raw spectra were first processed by five-point smoothing and first derivative.And then,moving window back propagation artificial neural network(MW-BP-ANN)was applied to select the characteristic spectral variables.After that,the calibration model was built by PLS,and the optimum model was achieved when 9 principal component scores(PCs)were included.The performances of the calibration models were evaluated according to root mean square error of predictionεRMSEP,correlation coefficient(C p)and residual prediction deviation(σRPD).The optimum results of the calibration model was achieved,andεRMSEP=19.965,C p=0.943 andσRPD=3.07.The overall results sufficiently demonstrate that NIR spectroscopy combined with PLS can be efficiently applied in the rapid identification of green tea production date.展开更多
Depression has been known to reduce the prefrontal activity associated with the execution of certain cognitive tasks, although whether a temporarily depressed or anxious mood in healthy individuals affects the prefron...Depression has been known to reduce the prefrontal activity associated with the execution of certain cognitive tasks, although whether a temporarily depressed or anxious mood in healthy individuals affects the prefrontal blood oxygen level during cognitive tasks is unknown. Combining the measurement of prefrontal activity with near-infrared spectroscopy (NIRS) and the two cognitive tasks, namely the letter version of the verbal fluency test (VFT-l) and the Stroop test, we measured the effect of a depressed or anxious mood and gender on the changes in the prefrontal oxygenated hemoglobin (Oxy-Hb) levels during those cognitive tests in healthy individuals. Depressed mood or anxious mood was assessed by the Hospital Anxiety and Depression Scale (HADS). Thereby we aimed to explore the possibility of NIRS measurement for detecting the early subclinical manifestation of major depression. Moreover, we examined the possible relationships between prefrontal activation and the functional Val66Met polymorphisms of the brain derived neurotropic factor (BDNF) gene and serum BDNF level. As a result, the increased prefrontal Oxy-Hb levels during cognitive tasks were significantly correlated with the severity of depressed mood in males. The course of the prefrontal Oxy-Hb increase was different depending on the cognitive tasks, i.e., the VFT-l or the Stroop test, in both genders. Correlations of BDNF genotype and serum BDNF level with the prefrontal Oxy-Hb levels during those cognitive tasks were negative. Our results suggest that the early subclinical manifestation of depressed mood in males might be detected by the NIRS measurement, which is not correlated with the individual properties of BDNF.展开更多
Sorafenib,a multikinase inhibitor used for the treatment of hepatocellular carcinoma,is limited by its low oral bioavailability.To overcome this drawback,we have developed novel camel milk casein-derived nanoparticles...Sorafenib,a multikinase inhibitor used for the treatment of hepatocellular carcinoma,is limited by its low oral bioavailability.To overcome this drawback,we have developed novel camel milk casein-derived nanoparticles as a drug delivery system.Camel milk casein is not only biocompatible on oral administration but is actually a dietary protein of pharmaceutical relevance.Casein is used because of its amphiphilic nature,self-assembling property,ability to show sustained release,and capability of encapsulating both hydrophilic and hydrophobic drugs.In this study,camel milk casein nanoparticles loaded with sorafenib were developed and characterized.Characterization of casein nanoparticles was done by dynamic light scattering(DLS),zeta potential analysis,scanning light microscopy(SEM),and FTIR.The drug content in nanoparticle and drug-protein binding studies were conducted by UV spectroscopy.The cytotoxicity and cellular uptake efficiency studies were performed in HepG2 cell lines.It was observed that the cytotoxic effect of sorafenib loaded camel milk casein nanoparticles was more than free sorafenib in HepG2 cells.This work suggests camel milk casein as a suitable drug delivery molecule for sorafenib.In the future,it may also be used in enhancing the efficacy and specific distribution of other water-insoluble anticancer drugs.展开更多
The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation s...The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged”[HC2nO·CO]+ cation complexes in 1600-3500 cm-1 frequency range. The geometric and electronic structures of the [HC2nO·CO]+ complexes and the core HC2nO+(n=3-6) cations are determined with the aid of density functional theory calculations. These HC2nO+(n=3-6) ions are identified to be linear carbon chain derivatives terminally capped by hydrogen and oxygen. The triplet ground states are 10-15 kcal/mol lower in energy than the singlet states, indicating cumulene-like carbon chain structures.展开更多
基金Natural Science Foundation of Jilin Province, China(No.200305502)
文摘A novel method for the determination of vitamin C（Vc） is proposed in this article. After the reaction with Folin-Ciocalteau reagent at ambient temperature, Vc solution was scanned at 750--1100 nm, and its first-order derivative spectrum were obtained from the original spectrum. The values of derivative selected at 995 nm were used for determination. It was proved that Vc could quickly react with Folin-Ciocalteau reagent within 5 min and the product was quite stable for a long time. The conditions required for this method is not very complicated, its precision and accuracy are similar to those of the iodometric titration described in Chinese Pharmacopoeia, and the limit of detection is 0.312 μg/mL. The determination of the results of vitamin C tablet, pill, and injection demonstrates that this method has wide pharmaceutical applications.
基金supported by the National Natural Science Foundation of China(No.223B2306)the Innovation Capability Support Program of Shaanxi Province(2023-CX-TD-49)the Natural Science Basic Research Program of Shaanxi Province(2025JC-JCQN-043).
文摘The rovibrational spectra of thioanisole(TA)and its halogenated derivatives,3-fluorothioanisole(3FTA)and 3-chlorothioanisole(3ClTA),were measured using synchrotron-based Fourier transform infrared spectroscopy(FTIR)at the Canadian Light Source.Combined with density functional theory calculations,the stable structures and vibrational modes of TA,3FTA,and 3ClTA in their vibrational states were analyzed.The theoretical vibrational mode frequencies were corrected by simulating the rotational structure of a vibrational band.The contributions of the cis-and trans-isomers of 3FTA and 3ClTA to the FTIR spectra at 298 K were estimated using the Boltzmann distribution,revealing their coexistence in the experimental spectra.The results indicate that both fluorine and chlorine substitution significantly affect the vibrational modes,particularly in the benzene ring.Compared to TA,the FTIR spectra of 3FTA and 3ClTA show changes in the frequencies and intensities of some vibrational modes,with halogen substitution causing specific modes to shift to higher wavenumbers.A comparison of the FTIR spectra of TA,3FTA,and 3ClTA highlights the influence of halogen substitution on vibrational properties,emphasizing how the type and position of the substituent affect frequency shifts and spectral intensities.These findings provide deeper insights into how halogenation alters vibrational spectra,which is crucial for further spectral analysis and molecular structure determination.
基金receiving a fellowship from UGCNew Delhi[University Grant Commission,the XIth plan(Faculty Improvement Programme)]DST and UGC for providing funds to the department under FIST and SAP programme
文摘A biologically active antibacterial reagent, 2-amino-6-hydroxy-4-（4-N, N-dimethylaminophenyl）-pyr- imidine-5-carbonitrile （AHDMAPPC）, was synthesized. It was employed to investigate the binding in- teraction with the bovine serum albumin （BSA） in detail using different spectroscopic methods. It ex- hibited antibacterial activity against Escherichia cali and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites （n ≈ 1） were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change （AH）, free energy （AG） and entropy change （AS） for the reaction were calculated to be 15.15 kJ/mol, -36.11 kJ/mol and 51.26J/mol K according to van＇t Hoff equation, respectively. The results indicated that the reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Forster＇s theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV-visible, synchronous fluorescence, circular dichroism （CD） and three-dimensional fluorescence spectra. All these results in- dicated that AHDMAPPC can bind to BSA and be effectively transported and eliminated in the body. It can be a useful guideline for further drug design.
文摘Azole derivatives such as 2-mercaptobenzothiazole(MBT) and 2-mercaptobenzimidazole(MBI) were introduced as corrosion inhibitors into the interlayer space of sodium montmorillonite clay(Na+-MMT). The corrosion protection behavior of mild steel in solutions containing MBT, MBI, MMT + MBT, MMT + MBI, Na^+-MMT, and NaCl(3.5 wt%) was evaluated using polarization and electrochemical impedance spectroscopy(EIS). Also, the release of penetrated species into the medium from the clay nanocarriers was evaluated using ultraviolet-visible(UV-Vis) spectroscopy. Small-angle X-ray scattering(SAXS) confirmed the insertion of MBT and MBI into the inner space of the clay layers and the interaction between two organic and inorganic phases. Scanning electron microscopy(SEM) was used to assess the morphology of the surface of the steel samples after the samples had been immersed for 24 h in the extraction solution. The corrosion protection in the solutions with clay nanocarriers containing MBT and MBI was better than that in solutions without MMT. The UV-Vis results showed that the release of MBI species from Na+-MMT nanocarriers in neutral pH was far lower than that of MBT species.
基金National Natural Science Foundation of China(No.61675151)
文摘In order to deal with the unclear absorption peak caused by the absorption peak overlap of traditional Chinese medicine(TCM)and other mixtures,a method of three unsupervised clustering algorithms as K-means,K-medoids and Fuzzy C-means(FCM)combined with the first derivative characteristics of terahertz absorption spectrum,is proposed to perform the terahertz spectra clustering of Sanchi and other three kinds of TCM compared with their easily-confused products(ECPs).These three unsupervised clustering methods complement the scope of the supervised learning classification method.The first derivative of the spectrum could amplify the difference in the absorption coefficient with different substances,so that the obvious absorption peak can be revealed.Experiments shows that these three clustering algorithms can achieve good results by combining the origin absorption coefficient with its first-order derivative as the characteristic data,and among which K-means does the best with the accuracy of95.32%.Compared with pure absorption coefficient data clustering,the accuracy in this study has been significantly improved,especially for the non-absorption-peak TCM classification.And the accuracy of K-means algorithm is improved by5.38%.Besides,clustering algorithms in this study have strong anti-interference ability to the error data.
基金Supported by National Natural Science Foundation of China(30960179)Program for Innovative Research Team in Science and Technology in University of Yunnan Province~~
文摘Fourier transform infrared （FTIR） spectroscopy was used to study diseased leaves in broad bean. Results showed that the infrared spectra of different broad bean diseased leaves were similar, which were mainly made up of the vibrational absorption bands of protein,lipid and polysaccharide.There were minor differences in-cluding the spectral peak position, peak shape and the absorption intensity in the range of 1 800-1 300 cm-1. There were obvious differences among their second derivative spectra in the range of 1 800-1 300 cm-1. After the procedure of the Fourier self-deconvolution and curve fitting of health bean leaves and broad bean diseased leaves in the range of 1 700-1 500 cm-1, three sub-peaks were obtained at 1 550 cm-1 （protein amide Ⅱ band）, 1 605 cm-1 （lignin） and 1 650 cm-1 （protein amide I band）.The ratios of relative areas of the bands of amide Ⅱ, lignin, and amide I were 38.86%, 28.68% and 32.47% in the spectra of healthy leaves, respec-tively. It was distinguished from the diseased leaves （chocolate spot leaf： 15.42%, 42.98% and 41.61%, ring spot leaf：32.39%, 35.63% and 31.98%, rust leaf： 13.97%, 46.40% and 39.65%, yel owing leaf curl disease leaf： 24.01%,36.55% and 39.44%）. For sub-peak area ratios （A1 563/A1 605, A1 650/A1 605 and A1 563/A1 654）, those of four kinds of diseased leaves were smal er than that of healthy leaves, and there were also differences among four kinds of diseased leaves. The results proved that FTIR combining with curve fitting might be a potential y useful tool for detecting different kinds of broad bean diseases.
基金financially supported by National Natural Science Foundation of China (Grant Nos. 51172255 and 51532006)
文摘Nucleation behavior of amorphous Si–B–C–N ceramics derived from boron-modified polyvinylsilazane procusors was systematically investigated by transmission electron microscopy(TEM) combined with spatially-resolved electron energy-loss spectroscopy(EELS) analysis. The ceramics were pyrolyzed at1000℃ followed by further annealing in N2, and SiC nano-crystallites start to emerge at 1200℃ and dominate at 1500℃. Observed by high-angle annular dark-field imaging, bright and dark clusters were revealed as universal nano-structured features in ceramic matrices before and after nucleation, and the growth of cluster size saturated before reaching 5 nm at 1400℃. EELS analysis demonstrated the gradual development of bonding structures successively into SiC, graphetic BNCxand Si3N4 phases, as well as a constant presence of unexpected oxygen in the matrices. Furthermore, EELS profiling revealed the bright SiC clusters and less bright Si3N4-like clusters at 1200–1400℃. Since the amorphous matrix has already phase separated into SiCN and carbon clusters, another phase separation of SiCN into SiC and Si3N4-like clusters might occur by annealing to accompany their nucleation and growth, albeit one crystallized and another remained in amorphous structure. Hinderance of the cluster growth and further crystallization was owing to the formation of BNCxlayers that developed between SiC and Si3N4-like clusters as well as from the excessive oxygen to form the stable SiO2.
基金financial support from Natural Science Foundation of China(61605134)Basic Sichuan Applied Research Project(2019YJ0078)the Innovative Spark Project of Sichuan University(2018SCUH0043)
文摘At present,two-dimensional(2D)materials have shown great application potential in numerous fields based on their physical chemical and electronic properties.Raman spectroscopy and de-rivative techniques are effective tools for characterizing 2D materials.Raman spectroscopy conveys lots of knowledge on 2D materials,including layer number,doping type,strain and interlayer coupling.This review summarized advanced applications of Raman spectroscopy in 2D materials.The challenges and possible applied directions of Raman spectroscopy to 2D materials are discussed in detail.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.81225023)the National Natural Science Fund of China(Nos.41476121, 81302691,81172978)+2 种基金the Innovation Program of Shanghai Municipal Education Commission(No.14YZ037)partially supported by Shanghai Subject Chief Scientist(No.12XD1400200)the financial support of the National High Technology Research and Development Program of China(863 Projects,No.2013AA092902)
文摘In this study,a convenient method using multi-step infrared spectroscopy,including Fourier transform infrared spectroscopy（FT-IR）,second derivative infrared spectroscopy（SD-IR） and two-dimensional correlation infrared spectroscopy（2DCOS-IR）,was employed to analyze and discriminate ten marine sponges from two classes collected from the Xisha Islands in the South China Sea.Each sponge had an exclusive macroscopic fingerprint.From the IR spectra,it was noted that the main ingredient of calcareous sponges was calcium carbonate,but that of demosponges was proteins.For sponges from the same genus or having highly similar chemical profile（IR spectral profile）,SD-IR and 2DCOS-IR were applied to successfully reveal the tiny differences.It was demonstrated that the multi-step infrared spectroscopy was a feasible and objective approach for marine sponge identification.
基金National Basic Research Program of China(No.JSJL2016210A001)State Key Laboratory of Sensor Technology Fund(No.SKT1507)
文摘Coupled with partial least squares(PLS),near infrared(NIR)spectroscopy was applied to develop a fast and nondestructive method to identify the production date of Rizhao green tea aiming at the deficiencies of the existing methods.In the modeling process,the raw spectra were first processed by five-point smoothing and first derivative.And then,moving window back propagation artificial neural network(MW-BP-ANN)was applied to select the characteristic spectral variables.After that,the calibration model was built by PLS,and the optimum model was achieved when 9 principal component scores(PCs)were included.The performances of the calibration models were evaluated according to root mean square error of predictionεRMSEP,correlation coefficient(C p)and residual prediction deviation(σRPD).The optimum results of the calibration model was achieved,andεRMSEP=19.965,C p=0.943 andσRPD=3.07.The overall results sufficiently demonstrate that NIR spectroscopy combined with PLS can be efficiently applied in the rapid identification of green tea production date.
文摘Depression has been known to reduce the prefrontal activity associated with the execution of certain cognitive tasks, although whether a temporarily depressed or anxious mood in healthy individuals affects the prefrontal blood oxygen level during cognitive tasks is unknown. Combining the measurement of prefrontal activity with near-infrared spectroscopy (NIRS) and the two cognitive tasks, namely the letter version of the verbal fluency test (VFT-l) and the Stroop test, we measured the effect of a depressed or anxious mood and gender on the changes in the prefrontal oxygenated hemoglobin (Oxy-Hb) levels during those cognitive tests in healthy individuals. Depressed mood or anxious mood was assessed by the Hospital Anxiety and Depression Scale (HADS). Thereby we aimed to explore the possibility of NIRS measurement for detecting the early subclinical manifestation of major depression. Moreover, we examined the possible relationships between prefrontal activation and the functional Val66Met polymorphisms of the brain derived neurotropic factor (BDNF) gene and serum BDNF level. As a result, the increased prefrontal Oxy-Hb levels during cognitive tasks were significantly correlated with the severity of depressed mood in males. The course of the prefrontal Oxy-Hb increase was different depending on the cognitive tasks, i.e., the VFT-l or the Stroop test, in both genders. Correlations of BDNF genotype and serum BDNF level with the prefrontal Oxy-Hb levels during those cognitive tasks were negative. Our results suggest that the early subclinical manifestation of depressed mood in males might be detected by the NIRS measurement, which is not correlated with the individual properties of BDNF.
文摘Sorafenib,a multikinase inhibitor used for the treatment of hepatocellular carcinoma,is limited by its low oral bioavailability.To overcome this drawback,we have developed novel camel milk casein-derived nanoparticles as a drug delivery system.Camel milk casein is not only biocompatible on oral administration but is actually a dietary protein of pharmaceutical relevance.Casein is used because of its amphiphilic nature,self-assembling property,ability to show sustained release,and capability of encapsulating both hydrophilic and hydrophobic drugs.In this study,camel milk casein nanoparticles loaded with sorafenib were developed and characterized.Characterization of casein nanoparticles was done by dynamic light scattering(DLS),zeta potential analysis,scanning light microscopy(SEM),and FTIR.The drug content in nanoparticle and drug-protein binding studies were conducted by UV spectroscopy.The cytotoxicity and cellular uptake efficiency studies were performed in HepG2 cell lines.It was observed that the cytotoxic effect of sorafenib loaded camel milk casein nanoparticles was more than free sorafenib in HepG2 cells.This work suggests camel milk casein as a suitable drug delivery molecule for sorafenib.In the future,it may also be used in enhancing the efficacy and specific distribution of other water-insoluble anticancer drugs.
基金supported by the National Natural Science Foundation of China (No.21688102, No.21433005, and No.21573047)
文摘The carbon chain cations, HC2nO+(n=3-6) are produced via a pulsed laser vaporization supersonic expansion ion source in the gas phase. Their infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged”[HC2nO·CO]+ cation complexes in 1600-3500 cm-1 frequency range. The geometric and electronic structures of the [HC2nO·CO]+ complexes and the core HC2nO+(n=3-6) cations are determined with the aid of density functional theory calculations. These HC2nO+(n=3-6) ions are identified to be linear carbon chain derivatives terminally capped by hydrogen and oxygen. The triplet ground states are 10-15 kcal/mol lower in energy than the singlet states, indicating cumulene-like carbon chain structures.
