Synergistic effect of Euphorbia kansui stir-fried with vinegar and bile acids on malignant ascites effusion through modulation of gut microbiota.

Background: Toxic Euphorbia kansui (EK) is employed to treat malignant ascites effusion (MAE). EK stir-fried with vinegar (VEK) has been demonstrated to reduce toxicity due to its preserved water-expelling effect. This was demonstrated to be correlated with gut microbiota. Therein, bile acids (BAs) have a bidirectional relationship with the gut microbiota. Therefore, the aim of this study is to explore whether BA-mediated gut microbiota influences the water-expelling effect of VEK against MAE. Methods: The MAE rat model was established by intraperitoneal injection of Walker-256 tumor cells. A reliable simultaneous method for the determination of 15 bile acids in rat feces using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established and applied to analyze the fecal BAs in rats treated with VEK. The screened BA was then administered to VEK-treated MAE rats. The water-expelling effect was evaluated using histopathological analysis, biochemical examination, inflammatory factors in ascites, urine volume, ascites amount, and intestinal aquaporin expression. The microbial composition was determined using 16S rRNA sequencing, and the contents of bile acids were finally measured. Results: VEK decreased the content of fecal deoxycholic acid (DCA), lithocholic acid (LCA), and taurocholic acid (TCA) while increasing the content of ursodeoxycholic acid (UDCA). VEK alleviated liver, stomach, and intestinal injuries; oxidative damage; and inflammation, which were further ameliorated with UDCA intervention. VEK alleviated MAE by increasing the fecal water content, urine volume, and AQP3 protein expression and decreasing the urine levels of Na+, K+, and Cl-. This was retained with the intervention of UDCA. UDCA and VEK regulated the BA metabolism disorder to a certain extent. Analysis of gut microbiota showed that VEK increased the abundance of Lactobacillus and decreased that of Prevotella_9 in MAE rats. The combined administration of UDCA and VEK showed a better modulation of the microbiota structure than that of VEK alone, and the effect of this administration reached closer to the reference state. Conclusion: The water-expelling effect of VEK did not directly depend on the BA-mediated gut microbiota. However, VEK and BAs had a synergistic effect on malignant ascites effusion through the regulation of the gut microbiota. These results provided a scientific basis for the reasonable usage of VEK and the novel combination treatment strategy of VEK and UDCA.

[Jujubae Fructus alleviates intestinal injury caused by toxic medicinals in Shizao Decoction based on correlation between intestinal flora and host metabolism].

Genkwa Fols, Kansui Radix, and Euphorbiae Pekinensis Radix in Shizao Decoction(SZD) are toxic to intestinal tract. Jujubae Fructus in this prescription can alleviate the toxicity, but the mechanism is still unclear. Therefore, this study aims to explore the mechanism. To be specific, 40 normal Sprague-Dawley(SD) rats were classified into the normal group, high-dose and low-dose SZD groups, and high-dose and low-dose SZD without Jujubae Fructus(SZD-JF) groups. The SZD groups were given(ig) SZD, while SZD-JF groups received the decoction without Jujubae Fructus. The variation of body weight and spleen index were recorded. The patho-logical changes of intestinal tissue were observed based on hematoxylin and eosin(HE) staining. The content of malondialdehyde(MDA) and glutathione(GSH) and activity of superoxide dismutase(SOD) in intestinal tissue were measured to evaluate the intestinal injury. Fresh feces of rats were collected to detect intestinal flora structure by 16S ribosomal RNA gene(16S rDNA) sequencing technology. The content of fecal short chain fatty acids and fecal metabolites was determined by gas chromatography-mass spectrometer(GC-MS) and liquid chromatography-mass spectrometer ultra-fast liquid chromatography-quadrupole-time-of-flight mass spectrometer(UFLC-Q-TOF-MS), separately. Spearman's correlation analysis was employed to analyze the differential bacteria genera and differential metabolites. RESULTS:: showed that high-dose and low-dose SZD-JF groups had high content of MDA in intestinal tissue, low GSH content and SOD activity, short intestinal villi(P<0.05), low diversity and abundance of intestinal flora, variation in the intestinal flora structure, and low content of short chain fatty acids(P<0.05) compared with the normal group. Compared with high-dose and low-dose SZD-JF groups, high-dose and low-dose SZD groups displayed low content of MDA in intestinal tissue, high GSH content and SOD activity, recovery of the length of intestinal villi, increased abundance and diversity of intestinal flora, alleviation of dysbacteria, and recovery of the content of short chain fatty acids(P<0.05). According to the variation of intestinal flora and fecal metabolites after the addition of Jujubae Fructus, 6 differential bacterial genera(Lactobacillus, Butyricimonas, Clostridia＿UCG-014, Prevotella, Escherichia-Shigella, Alistipes),4 differential short chain fatty acids(such as acetic acid, propionic acid, butyric acid, valeric acid) and 18 differential metabolites(such as urolithin A, lithocholic acid, and creatinine) were screened out. Beneficial bacteria such as Lactobacillus were in positive correlation with butyric acid and urolithin A(P<0.05). The pathogenic bacteria such as Escherichia-Shigella were in negative correlation with propionic acid and urolithin A(P<0.05). In summary, SZD-JF caused obvious intestinal injury to normal rats, which could lead to intestinal flora disorder. The addition of Jujubae Fructus can alleviate the disorder and relieve the injury by regulating intestinal flora and the metabolites. This study discusses the effect of Jujubae Fructus in relieving the intestinal injury caused by SZD and the mechanism from the perspective of intestinal flora-host metabolism, which is expected to serve as a reference for clinical application of this prescription.

Porcine cardiac blood - Salvia miltiorrhiza root alleviates cerebral ischemia reperfusion injury by inhibiting oxidative stress induced apoptosis through PI3K/AKT/Bcl-2/Bax signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Salvia miltiorrhiza Bge. mixed with porcine cardiac blood (PCB-DS) is mainly employed for the treatment of brain ischemia-induced mental disturbances, palpitations and phlegm confusion based on the traditional principle of Menghe medical sect. PCB is the guide to DS and enhances the effect of DS. However, the potential mechanism of PCB-DS preventing cerebral ischemia/reperfusion injury (CIRI) from the perspective of oxidative stress induced cell apoptosis remains unknown. AIM OF THE STUDY: To investigate the pharmacological activity and molecular mechanism of PCB-DS against CIRI. MATERIALS AND METHODS: DS samples processed with different methods were prepared and UPLC-Q-TOF-MS/MS was employed for qualitative analysis of the respective processing product. The middle cerebral artery occlusion reperfusion model was then established to investigate the pharmacological activities of PCB-DS. Pathological changes in the rat brain were observed by triphenyl tetrazolium chloride (TTC), hematoxylin-eosin, and TUNEL staining. The levels of IL-6, IL-1ß, and TNF-α were detected by ELISA to evaluate the inflammatory damage. Metabolomics of cerebrospinal fluid was further used to explore the potential mechanism of PCB-DS in preventing CIRI. Based on this, the levels of oxidative stress-related lactate dehydrogenase (LDH), reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were determined. The protein levels of PI3K, AKT, Bcl-2, Bax, cleaved-caspase-3, and cleaved-caspase-9 proteins of the cerebral infarct zone were finally measured by western blotting. RESULTS: Forty-seven components were identified in four processing products. Compared to DS, the content of total aqueous components in PCB-DS was significantly increased including salvianolic acid B isomer, salvianolic acid D, salvianolic acid F, and salvianolic acid H/I/J. Among the DS, DS processed with wine, DS processed with pig blood, and DS processed with porcine cardiac blood, PCB-DS best alleviated the CIRI through the neurological score, brain infarct volume, brain histopathology and the levels of inflammatory factors in the brain. Twenty-five significant metabolites in the cerebrospinal fluid were screened out between the sham and I/R groups. They were mainly involved in the beta-alanine metabolism, histidine metabolism, and lysine degradation, which indicated that PCB-DS may inhibit oxidative stress-induced apoptosis to achieve treating ischemic stroke. The results of biomedical examination showed that PCB-DS could alleviate oxidative damage, significantly downregulate the expression of Bax, cleaved caspase-3 and cleaved caspase-9, and upregulate the expression of p-PI3K, p-AKT, and Bcl-2. CONCLUSION: In summary, this study demonstrated that PCB-DS alleviated CIRI and the molecular mechanism may be related to inhibiting the oxidative stress induced apoptosis through PI3K/AKT/Bcl-2/Bax signaling pathway.

[Optimization of parameters for stir-frying of Kansui Radix with vinegar based on conversion of toxic components].

This study aims to optimize the parameters for stir-frying of Kansui Radix with vinegar based on the conversion of representative toxic diterpenes, which is expected to serve as a reference for the standardized production of Kansui Radix stir-fried with vinegar. To be specific, the toxic components [3-O-(2'E,4'Z-decadienoyl)-20-O-acetylingenol(3-O-EZ), kansuiphorin C(KPC)] in Kansui Radix and the products(ingenol, 20-deoxyingenol) after the stir-frying with vinegar were selected. The toxicity to intestine and water-draining activity were evaluated with NCM460(normal human colon mucosal epithelial cell line) and HT-29(a human colorectal adenocarcinoma cell line). An HPLC method was then developed to assess the conversion of toxic components. On this basis, temperature, time, and amount of vinegar for the processing of Kansui Radix were optimized with the Box-Behnken design and the content of ingenol and 20-deoxyingenol as evaluation index. The results showed that after the stir-frying of Kansui Radix with vinegar, 3-O-EZ and KPC were first converted to monoester 3-O-(2'E,4'Z-decadienoyl)ingenol(3-EZ) and 5-O-benzoyl-20-deoxyingenol(5-O-Ben) and finally to almost non-toxic ingenol and 20-deoxyingenol, respectively. Meanwhile, the water-draining activity was retained. Six compounds had a good linear relationship with the peak area in the corresponding concentration ranges(R~2≥0.999 8), and the average recovery fell in the range of 98.20%-102.3%(RSD≤2.4%). The content of representative diterpenes and intermediate products was 14.78%-24.67% lower in the Kansui Radix stir-fried with vinegar than in the Kansui Radix, while the content of the conversed products was 14.37%-71.37% higher. Among the process parameters, temperature had significant influence on the total content of products, followed by time. The optimal parameters were 210 ℃, 15 min, and 30% vinegar. The relative error between the experimental results and the predicted values was 1.68%, indicating that the process was stable and reproducible. The strategy of screening optimal parameters for stir-frying of Kansui Radix with vinegar based on the transformation of toxic components can help improve the production stability, reduce the toxicity, and ensure the efficacy of Kansui Radix stir-fried with vinegar, which can serve as a reference for the process optimization of similar toxic Chinese medicinals.

Chemical profile and miscarriage prevention evaluation of Jiao-Ai Decoction, a classical traditional Chinese formula.

Jiao-Ai Decoction (JAD), a classical traditional Chinese formula composed of seven Chinese herbs, has been widely used in clinical practice for the treatment of abortion for a long time. However, the material basis and pharmacological mechanism remain unclear. An integrative method combining ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) analysis and therapeutic effect evaluation based on the hypothalamus-pituitary-ovarian axis (HPOA) was employed to elaborate these problems. Firstly, the chemical profile of JAD was identified by UPLC-Q-TOF-MS. Secondly, the main target ingredients from JAD were determined by UPLC-T-Q-MS. Finally, the miscarriage prevention of JAD on threatened abortion pregnant rats induced by mifepristone was investigated. Threatened abortion model in rats were replicated, uterine bleeding quantity (UBQ) and histopathological sections were measured, the contents of luteinizing hormone (LH), follicular stimulating hormone (FSH), estradiol (E2) and progesterone (P) were determined by ELISA, related genes and protein expression levels were detected by RT-PCR and western blotting. As a result, a total of 101 compounds were identified and 27 ingredients were determined to evaluate the quality of JAD. In the model rats, JAD could effectively regulate the HPOA to achieve miscarriage prevention, and the mechanism might be related to the regulation of gene and protein expression on the HPOA. This work could provide a novel and valuable approach for the quality evaluation of JAD and were expected to provide ideas and methods for the basic research on the scientific application of similar traditional Chinese medicine prescriptions.

[Chemical ingredient groups B and C in Kansui Radix stir-fried with vinegar affect diversity of gut microbiota in rat model of malignant ascites induced by Walker-256 cells].

This study aims to explore the effects of chemical ingredient groups B and C in Kansui Radix stir-fried with vinegar on the diversity of gut microbiota in the rat model of malignant ascites, identify the key differential microbial taxa, and reveal the biological mechanism of water-expelling effect of the two chemical ingredient groups. The rat model of malignant ascites induced by Walker-256 cells was established, and phenolphthalein was used as the positive drug. The rats were orally administrated with corresponding agents for consecutive 7 days. On day 6, fresh feces samples were collected from the rats, and 16 S rDNA high-throughput sequencing and GC-MS were employed to determine the composition of gut microbiota and the content of short-chain fatty acids, respectively. On day 7, serum and intestinal tissue samples were collected for the determination of related indicators. Compared with the control group, the model group showed decreased feces volume and urine volume(P<0.01), increased volume of ascites and levels of Na~+, K~+, and Cl~- in urine(P<0.01), down-regulated mRNA and protein levels of intestinal AQP8(P<0.01), lowered abundance of beneficial Lactobacillus(P<0.01) while risen abundance of potential pathogenic Lachnospiraceae and Anaeroplasma(P<0.01), and reduced content of short-chain fatty acids(P<0.01). Compared with the model group, administration with chemical ingredient groups B and C alleviated all the above indicators(P<0.01). In conclusion, chemical ingredient groups B and C in Kansui Radix stir-fried with vinegar could alleviate the disordered gut microbiota in rats with malignant ascites to expel water through increasing the abundance of beneficial Lactobacillus and reducing the abundance of harmful Lachnospiraceae and Anaeroplasma. This study can provide a reference for the reasonable clinical application of Kansui Radix stir-fried with vinegar.

[Effect of Kansui Radix stir-fried with vinegar on fecal metabolomics in Walker-256 rats with ascites].

Utilizing metabolomics technology, this study explored the change of fecal endogenous metabolites in Walker-256 rats with malignant ascites after the administration with Kansui Radix(KR) stir-fried with vinegar(VKR), sought the potential biomarkers in feces which were related to the treatment of malignant ascites by VKR and revealed the biological mechanism of water-expelling effect of VKR. Ultra-fast liquid chromatography-quadrupole-time-of-flight mass spectrometry(UFLC-Q-TOF-MS) was employed to detect the feces of rats in all groups. Principle component analysis(PCA) and partial least squares discriminant analysis(PLS-DA) were conducted to achieve pattern recognition. Combining t-test and variable importance in the projection(VIP) enabled the screening of potential biomarkers for the malignant ascites. Metabolic pathway analysis was accomplished with MetaboAnalyst. Correlation analysis was finally conducted integrating the sequencing data of gut microbiota to elucidate the mechanism underlying the water-expelling effect of VKR. The results showed that both KR and VKR could restore the abnormal metabolism of model rats to some extent, with VKR being inferior to KR in the regulation. Eleven potential biomarkers were identified to be correlated with the malignant ascites and five metabolic pathways were then enriched. Four kinds of gut microbiota were significantly related to the potential biomarkers. The water-expelling effect of VKR may be associated with the regulation of phenylalanine metabolism, biosynthesis of phenylalanine, tyrosine and tryptophan, tryptophan metabolism, glycerophospholipid metabolism, and glycosylphosphatidylinositol(GPI)-anchor biosynthesis. This study can provide a scientific basis for comprehensive understandings of the interaction between gut microbiota and host which has relation to the water-expelling effect of VKR and guide the reasonable clinical application of VKR.

Comparison of content-toxicity-activity of six ingenane-type diterpenoids between Euphorbia kansui before and after stir-fried with vinegar by using UFLC-MS/MS, zebrafish embryos and HT-29 cells.

The dried roots of Euphorbia kansui (EK) are especially beneficial for the treatment of edema, but the severe toxicity limits their clinical applications. Euphorbia kansui stir-fried with vinegar (VEK) is traditionally employed to reduce the toxicity of EK. However, the material basis for the toxicity reduction with effectivity conservation is still unclear. Therefore, in this study, a rapid, sensitive, and reliable ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS) method was firstly established to simultaneously determine six ingenane-type diterpenoids, i.e. kansuiphorin C (1), 5-O-benzoyl-20-deoxyingenol (2), 20-deoxyingenol (3), 3-O-(2'E,4'E-decadienoyl)-20-O-acetylingenol (4), 20-O-(2'E,4'Z-decadienoyl)ingenol (5), and ingenol (6), in EK and VEK based on the processing conversion. Then, the toxicity evaluation on zebrafish embryos and modulation of the expression of aquaporin-3 (AQP3) proteins in HT-29 cells were employed to investigate the toxicity-activity of six compounds. Chromatographic separation was obtained on Waters BEH RP18 column (2.1 mm × 100 mm, 2.5 µm) with the mobile phase composed of 0.1 % formic acid in acetonitrile and water, respectively. The column temperature was 35 ℃ at a flow rate of 0.4 mL min-1. Multiple reaction monitoring was conducted in both positive and negative modes for quantitative analysis. The method was then successfully used for the determination of six compounds in EK and VEK. In addition, 1, 2, 4, and 5 had evident cardiotoxicity, intestinal irritation and nutrient absorption disorders on zebrafish larvae, while no in-vivo toxicity was seen for groups given 3 and 6 (LC50 > 200 µM). Meanwhile, 1, 2, 4, 5, and 6 significantly increased the expression of AQP3 protein (p < 0.05) to promote the excretion of water in the colon. This study demonstrated that toxic ingenane-type diterpenoids converted into the less toxic compounds with the same core structure through the breakage of multiple ester bonds in the side chain. At the same time, the laxative effect was retained, providing useful information for the optimization of the process of EK and quality evaluation of other similar toxic Chinese herbal medicines.

Kansuiphorin C and Kansuinin A ameliorate malignant ascites by modulating gut microbiota and related metabolic functions.

ETHNOPHARMACOLOGICAL RELEVANCE: Euphorbia kansui is a toxic Chinese herbal medicine and exhibits promising treatment to the malignant ascites (MA) in its traditional use. Ingenane-type and jastrophane-type diterpenes are demonstrated to be responsible for the toxicity and efficacy of kansui. Two representative compounds, kansuiphorin C (KPC) and kansuinin A (KA) in each type were proved to effectively reduce the ascites. The biological and toxicological effects are closely associated with the gastrointestinal tract, but the possible mechanism and related metabolic functions of KPC and KA treating MA through modulating the gut microbiota remain unclear. AIM OF THE STUDY: To investigate the possible mechanism and related metabolism of KPC and KA ameliorating malignant ascites through modulating gut microbiota. MATERIALS AND METHODS: MA rats and normal rats were divided into different groups and administrated with KPC, KA, and positive drug, respectively. 16S rDNA gene sequencing and metagenomes analysis combined with the quantification of short-chain fatty acids of feces were performed to reflect the modulation of gut microbiota. Then, the metabolites of KPC and KA in rat feces under the normal and pathological circumstances were detected by ultra-fast liquid chromatography coupled with MS/MS detector (UFLC-MS/MS) to explore the in-vivo bacterial biotransformation. RESULTS: KPC and KA were modulatory compounds for gut microbiota. The richness of Lactobacillus and the decreased abundance of Helicobacter involved in the carbohydrate metabolism and amino acid metabolism could be responsible for their prohibitory effects on malignant ascites. KPC exhibited stronger modulation of gut microbiota through making the abundance of Helicobacter about 3.5 times lower than KA. Besides, in-vivo microbial biotransformation of KPC and KA contained oxidation, hydrolysis, dehydration, and methylation to form metabolites of lower polarity. Besides, at the dosage of 10 mg kg-1, the toxicity of both compounds had weaker influences on the gut microbiota of normal rats. CONCLUSION: KPC and KA could ameliorate malignant ascites by modulating gut microbiota mainly containing the increase of Lactobacillus and the decrease of Helicobacter and related carbohydrate and amino acid metabolism, providing a basis for their promising clinical usage.

Toxicity Reduction of Euphorbia kansui Stir-Fried with Vinegar Based on Conversion of 3-O-(2'E,4'Z-Decadi-enoyl)-20-O-acetylingenol.

The dried roots of Euphorbia kansui S.L.Liou ex S.B.Ho have long been used to treat edema in China. However, the severe toxicity caused by Euphorbia kansui (EK) has seriously restricted its clinical application. Although EK was processed with vinegar to reduce its toxicity, the detailed mechanisms of attenuation in toxicity of EK stir-fried with vinegar (VEK) have not been well delineated. Diterpenoids are the main toxic ingredients of EK, and changes in these after processing may be the underlying mechanism of toxicity attenuation of VEK. 3-O-(2'E,4'Z-decadienoyl)-20-O-acetylingenol (3-O-EZ) is one of the diterpenoids derived from EK, and the content of 3-O-EZ was significantly reduced after processing. This study aims to explore the underlying mechanisms of toxicity reduction of VEK based on the change of 3-O-EZ after processing with vinegar. Based on the chemical structure of 3-O-EZ and the method of processing with vinegar, simulation experiments were carried out to confirm the presence of the product both in EK and VEK and to enrich the product. Then, the difference of peak area of 3-O-EZ and its hydrolysate in EK and VEK were detected by ultra-high-performance liquid chromatography (UPLC). Furthermore, the toxicity effect of 3-O-EZ and its hydrolysate, as well as the underlying mechanism, on zebrafish embryos were investigated. The findings showed that the diterpenoids (3-O-EZ) in EK can convert into less toxic ingenol in VEK after processing with vinegar; meanwhile, the content of ingenol in VEK was higher than that of EK. More interestingly, the ingenol exhibited less toxicity (acute toxicity, developmental toxicity and organic toxicity) than that of 3-O-EZ, and 3-O-EZ could increase malondialdehyde (MDA) content and reduce glutathione (GSH) content; cause embryo oxidative damage by inhibition of the succinate dehydrogenase (SDH) and superoxide dismutase (SOD) activity; and induce inflammation and apoptosis by elevation of IL-2 and IL-8 contents and activation of the caspase-3 and caspase-9 activity. Thus, this study contributes to our understanding of the mechanism of attenuation in toxicity of VEK, and provides the possibility of safe and rational use of EK in clinics.

Pricing strategy of multi-oligopoly airlines based on service quality.

In recent years, with the rapid development of China's air transport industry and the change in market consumption structure, service quality has become one of the important factors affecting airline revenue. How to formulate a reasonable pricing strategy and maintain competitiveness in the fierce market competition has become an urgent problem for airlines. First, the impact factor of service quality level in the traditional pricing model is introduced and a static price competition model for multi-oligopoly airlines based on service quality is established in this paper. And then, a dynamic pricing model based on service quality of the multi-oligopoly airlines is established. The model incorporates the weight factor of service quality impact, which is used to indicate the weight of the service quality level in the process of airline dynamic pricing. The research results show that the service quality level of airlines has an indispensable influence on its development. Airlines should improve service quality as soon as possible to enhance market competitiveness and achieve sustainable development.

[Discharge ion mobility spectrometry of ketonic organic compounds].

Ion mobility spectrometry (IMS) is a sensitive technique for fast on-line monitoring trace volatile organic compounds based upon the mobilities of gas phase ions at ambient pressure in weak electric field. In the present work, protonated water reactant ions were successfully prepared, and eight ketones were studied on a homemade high-resolution IMS apparatus using a discharge ionization source. The reduced mobility values of all ions were derived from the observed ion mobility spectra. The experimentally determined reduced mobilities for acetone, 2-butone, 1-methyl-2-pyrrolidinone acetophenone, cyclohexanone and product ions were compared with the previously reported values in the Ni-IMS, indicating that they are in good agreement. The reduced mobilities of methyl isopropyl ketone, 4-methyl-2-pentanone and cyclopentanone ions were given for the first time. The ionization process for organic compounds in the authors' discharge ion mobility spectrometer is suggested to be similar to Ni-IMS system, i.e., the proton transfer reactions produce protonated ketone ions. In addition, a linear correlation was found between the reduced mobilities of the ketone ions and their molecular masses. Qualitative measurements show that the limit of detection is in the ng x L(-1) order of magnitude in the authors' discharge ion mobility spectrometer.

[Ion mobility spectrometry for the isomeric volatile organic compounds].

Ion mobility spectrometry (IMS) is based on determining the drift velocities, which the ionized sample molecules attain in the weak electric field of a drift tube at atmospheric pressure. The drift behavior can be affected by structural differences of the analytes, so that ion mobility spectrometry has the ability to separated isomeric compounds. In the present article, an introduction to IMS is given, followed by a description of the instrument used for the experiments to differentiate isomeric compounds. Positive ion mobility spectras of three kinds of isomeric volatile organic compounds were studied in a homemade high-resolution IMS apparatus with a discharge ionization source. The study includes the differences in the structure of carbon chain, the style of function group, and the position of function group. The reduced mobility values were determined, which are in very good agreement with the previously reported theoretical values using neural network theory. The influence of the structural features of the substances and including the size and shape of the molecule has been investigated. The reduced mobility values increases in the order: alcohols < acetones < aromas, linears < branches < cycles, and para- < meta- < ortho-. The deviating ion mobility spectra of the constitutional isomers studied reflect the influence of structural features. In order to calibrate or determine the detection limits and the sensitivity of the ion mobility spectrometry, the exponential dilution flask (EDF) was used. Using this method, the detection limit of the analytes can reach the order of magnitude of ng x L(-1).

Performance of the atomic and molecular physics beamline at the National Synchrotron Radiation Laboratory.

At the National Synchrotron Radiation Laboratory, The University of Science and Technology of China, an atomic and molecular physics beamline with an energy range of 7.5-124 eV has been constructed for studying the spectroscopy and dynamics of atoms, molecules and clusters. The undulator-based beamline, with a high-resolution spherical-grating monochromator (SGM), is connected to the atomic and molecular physics end-station. This end-station includes a main experimental chamber for photoionization studies and an additional multi-stage photoionization chamber for photoabsorption spectroscopy. A mid-photon flux of 5 x 10(12) photons s(-1) and a high resolving power is provided by this SGM beamline in the energy range 7.5-124 eV. The size of the synchrotron radiation beam spot at the sample is about 0.5 mm in the vertical direction and 1.0 mm in the horizontal direction. Some experimental results of photoionization efficiency spectroscopy and photoabsorption spectroscopy of atoms and molecules are also reported.

[Highly sensitive tunable diode laser absorption spectroscopy of CO2 around 1.31 microm].

Fifteen new absorption lines were observed when studying CO2 absorption spectroscopy by wavelength modulation (WM) technique with a DFB laser. The line intensity we can detect is 2.251 63 x 10(-27) cm(-1) x (moleculecm(-2))(-1) at 6.67 x 10(2) Pa pressure, corresponding to an absorbance of 3. 88 x 10(-8). The overtone spectra of CO2 around 1.31 microm have been measured with a tunable diode laser and the corresponding spectral parameters (positions, intensities, and self-broadening coefficients) are presented.