[Determination of three new herbicide residues in soil, sediment and water by liquid chromatography-tandem mass spectrometry].

Herbicides play an important role in preventing and controlling weeds and harmful plants and are increasingly used in agriculture, forestry, landscaping, and other fields. However, the effective utilization rate of herbicides is only 20%-30%, and most herbicides enter the atmosphere, soil, sediment, and water environments through drift, leaching, and runoff after field application. Herbicide residues in the environment pose potential risks to ecological safety and human health. Therefore, establishing analytical methods to determine herbicide residues in environmental samples is of great importance. In this study, an analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization mode (ESI+) was developed for the determination of isoxaflutole, metazachlor, and saflufenacil residues in soil, sediment, and water. The instrumental detection parameters, including electrospray ionization mode, mobile phase, and chromatographic column, were optimized. The mobile phases were methanol (A) and 0.1% formic acid aqueous solution (B). Gradient elution was performed as follows: 0-1.0 min, 60%A; 1.0-2.0 min, 60%A-90%A; 2.0-3.0 min, 90%A; 3.0-4.0 min, 90%A-60%A; 4.0-5.0 min, 60%A. The samples were salted after extraction with acetonitrile and cleaned using a C18 solid-phase extraction column. Different solid-phase extraction columns and leaching conditions were investigated during sample pretreatment. Working curves in the neat solvent and matrix were constructed by plotting the measured peak areas as a function of the concentrations of the analytes in the neat solvent and matrix. Good linearities were found for isoxaflutole, metazachlor, and saflufenacil in the solvent and matrix-matched standards in the range of 0.0005-0.02 mg/L, with r≥0.9961. The matrix effects of the three herbicides in soil, sediment, and water ranged from -10.1% to 16.5%. The limits of detection (LODs, S/N=3) for isoxaflutole, metazachlor, and saflufenacil were 0.05, 0.01, and 0.02 µg/kg, respectively. The limits of quantification (LOQs, S/N=10) for isoxaflutole, metazachlor, and saflufenacil were 0.2, 0.05, and 0.05 µg/kg, respectively. The herbicides were applied to soil, sediment, and water at spiked levels of 0.005, 0.1, and 2.0 mg/kg, respectively. The average recoveries for isoxaflutole, metazachlor, and saflufenacil in soil, sediment, and water were in the ranges of 77.2%-101.9%, 77.9%-105.1%, and 80.8%-107.1%, respectively. The RSDs for isoxaflutole, metazachlor, and saflufenacil were in the ranges of 1.4%-12.8%, 1.2%-7.7%, and 1.5%-11.5%, respectively. The established method was used to analyze actual samples collected from four different sites in Zhejiang Province (Xiaoshan, Taizhou, Dongyang, and Yuhang) and one site in Heilongjiang (Jiamusi). The proposed method is simple, rapid, accurate, stable, and highly practical. It can be used to detect isoxaflutole, metazachlor, and saflufenacil residues in soil, sediment, and water and provides a reference for monitoring the residual pollution and environmental behavior of herbicides.

Influencing factors of negative conversion time of nucleic acid detection in 228 patients infected with Omicron variant of SARS-CoV-2 in Shanghai / 中国热带医学

@#Abstract: Objective To analyze and compare the effects of different clinical characteristics on the negative conversion time of nucleic acid detection after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant infection, and to provide a scientific basis for the isolation and treatment of coronavirus disease 2019 (COVID-19). Methods　The epidemiological and clinical data of 228 mild SARS-CoV-2 Omicron variant infected patients diagnosed in Shanghai were retrospectively collected from April 27, 2022 to June 8, 2022 in Wujiaochang designated Hospital, Yangpu District, Shanghai. The negative conversion time of nucleic acid detection was used as the outcome variable, and the patients were divided into A (≤18 days) and B (>18 days). Univariate and multivariate logistic regression analysis were used to analyze the influencing factors of the negative conversion time of nucleic acid detection. Results　The mean nucleic acid conversion time of 228 patients was (18.7±12.1) d, with the median time of 18 (2-46) d. Among them, 120 patients in group A had an average nucleic acid conversion time of (13.2±2.0) d, and 108 cases in group B had an average nucleic acid conversion time of (20.8±1.3) d. Univariate analysis showed that there were no statistically significant differences in the effects of hypertension, coronary heart disease, diabetes, hypokalemia, malignant tumors, neuropsychiatric diseases, chronic digestive diseases on the negative nucleic acid conversion time (P>0.05); however, there were significant differences in the effects of combined cerebrovascular disease, leukopenia, chronic respiratory system diseases and vaccination on the negative nucleic acid conversion time (P<0.05). Further multivariate logistic regression analysis revealed that the combination of chronic respiratory diseases and non-vaccination were significant risk factors for prolongation of negative nucleic acid conversion time (P<0.05). Conclusions The results of this study show that gender, age and whether hypertension, coronary heart disease, diabetes mellitus, hypokalemia, malignant tumor, neuropsychiatric disease and chronic digestive disease have no significant effect on the nucleic acid conversion time, whereas chronic respiratory disease and no vaccination are significantly correlated with the prolongation of nucleic acid conversion time in SARS-CoV-2 Omicron-infected patients.

Promising Therapeutic Functions of Bone Marrow Mesenchymal Stem Cells Derived-Exosome in Asthma.

Asthma is a chronic inflammatory disturbance of the airways in which many cells and cellular elements are involved. Wheezing, breathlessness, chest tightness, and coughing, especially at night or in the early morning, are typical symptoms of asthma. At present, inhaled corticosteroid (ICS) and long-acting ß-agonists (LABAs) are standard treatments for regular management. Oral corticosteroids (OCSs) were recommended for controlling asthma exacerbation but only for a short-term treatment because of the side effects on organs. Biologic therapies have achieved exciting and notable effects in clinical treatment but are not applicable for all phenotypes of asthma. At present, some new approaches are under exploration to lessen side effects and improve curative effects. Studies have revealed that bone marrow mesenchymal stem cells (BMMSCs) hold various curative effects in asthma and may benefit in the long term with high safety. Extracellular vesicles (EVs) enriched in body fluid were characterized as subcomponents of extracellular vesicles and delivered carriers combined with genetic messages in vivo. The therapeutic potential of exosomes has become a research hotspot in many diseases. BMMSC-derived exosomes were considered as the dominant part of BMMSCs in cell-to-cell communications and playing curative effects. Points also hold that BMMSC-Exo could interfere with airway inflammation and airway remolding in asthma via modulating the immune response, regulating gene expression, adjusting the phenotype of macrophage, etc. However, BMMSC-Exo still lacked more clinical trials for evaluating the effects on asthma, and the technology of extraction and purification still needs to be improved for wide use. This review aims to draw the relationship among asthma, BMMSC, and exosome, which may provide innovate ideas for treatment of asthma, and arouse attention about the curative potential of BMMSC-Exo.

TDP-43 upregulates lipid metabolism modulator ABHD2 to suppress apoptosis in hepatocellular carcinoma.

TAR DNA-Binding Protein 43 (TDP-43) has been well studied in neurodegenerative diseases, but its potential role in malignance is still unclear. Here, we demonstrate that TDP-43 contributes to the suppression of apoptosis by facilitating lipid metabolism in hepatocellular carcinoma (HCC). In HCC cells, TDP-43 is able to suppress apoptosis while deletion of it markedly induces apoptosis. RNA-sequencing identifies the lipid metabolism gene abhydrolase domain containing 2 (ABHD2) as the target gene of TDP-43. Tissue microarray analysis shows the positive correlation of TDP-43 and ABHD2 in HCC. Mechanistically, TDP-43 binds with the UG-rich sequence1 of ABHD2 3'UTR to enhance the mRNA stability of ABHD2, thereby upregulating ABHD2. Afterwards, TDP-43 promotes the production of free fatty acid and fatty acid oxidation-originated reactive oxygen species (ROS) in an ABHD2-dependent manner, so as to suppress apoptosis of HCC. Our findings provide insights into the mechanism of HCC progression and reveal TDP-43/ABHD2 as potential targets for the precise treatment of HCC.

Studies on Dissipations and Residues of Indoxacarb under Different Field and Environmental Conditions.

Indoxacarb is a broad-spectrum insecticide and widely used in agriculture. The dissipations and residues of indoxacarb were researched at three different field sites in Beijing, Hunan, and Zhejiang provinces in China. Analytical methods for determining the residue of indoxacarb in paddy water, paddy soil, rice straw, rice hull, and brown rice were described. Indoxacarb residues were extracted from samples, cleaned up by solid phase extraction, and determined by high-performance liquid chromatography coupled with tandem mass spectrometry in the selected ion monitoring mode. The recoveries in paddy water, paddy soil, rice straw, rice hull, and brown rice matrices at three spiking levels ranged from 79.7% to 98.3%, respectively. The field and environmental conditions would affect the dissipations and residues of indoxacarb. The time to dissipate 50% of indoxacarb in paddy water, paddy soil, and rice straw was less than 9 days. The terminal residues obtained from Beijing at preharvest interval of 14 and 21 days were higher than the maximum limit of European Union. Therefore, a dosage of 24 g a. i. ha-1 at 28 days preharvest interval with 3 spraying times was recommended. Such accumulation of measured data is necessary to provide guidance for the proper and safe use of this pesticide.

[Clinical features of children with SARS-CoV-2 infection: an analysis of 13 cases from Changsha, China].

OBJECTIVE: To study the clinical features of children with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: A retrospective analysis was performed for the clinical data of 13 children with SARS-CoV-2 infection who hospitalized in a Changsha hospital. RESULTS: All 13 children had the disease onset due to family aggregation. Of the 13 children, 2 had no symptoms, and the other 11 children had the clinical manifestations of fever, cough, pharyngeal discomfort, abdominal pain, diarrhea, convulsions, or vomiting. As for clinical typing, 7 had mild type, 5 had common type, and 1 had severe type. The median duration of fever was 2 days in 6 children. All 13 children had normal levels of peripheral blood lymphocyte counts, immunoglobulins, CD4, CD8, and interleukin-6. The median time to clearance of SARS-CoV-2 was 13 days in the nasopharyngeal swabs of the 13 children. Three children presented false negatives for RT-PCR of SARS-CoV-2. SARS-CoV-2 RNA remained detectable in stools for 12 days after the nasopharyngeal swab test yielded a negative result. Abnormal CT findings were observed in 6 children. All 13 children were cured and discharged and they were normal at 2 weeks after discharge. CONCLUSIONS: Intra-family contact is the main transmission route of SARS-CoV-2 infection in children, and there is also a possibility of fecal-oral transmission. Mild and common types are the major clinical types in children with SARS-CoV-2 infection, and cytokine storm is not observed. Children with SARS-CoV-2 infection tend to have a good short-term prognosis, and follow-up is needed to observe their long-term prognosis. Multiple nucleic acid tests should be performed for patients with SARS-CoV-2 infection and their close contacts by multiple site sampling.

Serum miR-632 is a potential marker for the diagnosis and prognosis in laryngeal squamous cell carcinoma.

Background: It has been demonstrated that miRNAs play critical roles in the tumorigenesis and progression of various tumors.Objective: The purpose of this research was to determine the serum miR-632 levels in patients with laryngeal squamous cell carcinoma (LSCC) and to investigate its diagnostic and prognostic value.Materials and methods: We detected serum miR-632 levels in 162 LSCC patients and 42 healthy volunteers. The ROC curve was carried out to determine diagnostic accuracy.Results: We observed that serum miR-632 levels were upregulated in LSCC patients compared with healthy volunteers (p < .01). Subsequent results from ROC indicated that high sensitivity and specificity of serum miR-632 for diagnosing LSCC (area under the curve 0.8828). In addition, it was found that high expressions of serum miR-632 were significantly associated with advanced N stage (p = .020), histological grade (p = .001), and TNM stage (p = .014). Furthermore, patients with higher serum miR-632 expression had a shorter OS and DFS time than those with lower serum miR-632 levels.Conclusion: Our data revealed that serum miR-632 may be a potential noninvasive biomarker which may become a potential diagnostic and prognostic biomarker for LSCC patients.

The effects of tonsillectomy by low-temperature plasma on the growth development and psychological behavior in children with obstructive sleep apnea hypopnea syndrome.

We investigated the effects of tonsillectomy by low-temperature plasma on the growth development and psychological behavior in children with obstructive sleep apnea hypopnea syndrome (OSAHS).This study included 72 moderate and severe OSAHS children with tonsils or adenoids hypertrophy, which were randomly assigned into either the study group (n = 36) or the control group (n = 36). Patients in study group underwent tonsillectomy by low-temperature plasma, while in the control group underwent tonsil-pecking, then the efficacy were compared.The time of surgery, VAS scores on postoperative day 1, 3, and 7 were significantly lower in the study group than in the control group, and the efficiency was significantly higher in the study group than the control group (P = .018). In the study group, the BMI was lower, the score of C-WISC (VIQ, PIQ, and FIQ) was higher, the score of CBCL social competence was higher and the score of behavioral questions was lower than that in the control group; differences were statistically significant (P = .022). The serum levels of IgA, IgG, and IgM, as well as the percentage of T lymphocytes, between the study group and the control group were not significantly different (P = .132).Tonsillectomy by low-temperature plasma was effective on the treatment of children with severe OSAHS, and could improve growth development and psychological behavior.

A theoretical study on the oxidation of alkenes to aldehydes catalyzed by ruthenium porphyrins using O2 as the sole oxidant.

Density functional theory (DFT) calculations were used to study the ruthenium porphyrin-catalyzed oxidation of styrene to generate an aldehyde. The results indicate that two reactive oxidants, dioxoruthenium and monooxoruthenium-superoxo porphyrins, participate in the catalytic oxidation. In the mechanism, the resultant monooxoruthenium porphyrin acts in the tandem epoxide isomerization (E-I) to selectively yield an aldehyde and generate a dioxoruthenium porphyrin, thereby triggering new oxidation reaction cycles. In this calculation, several key elements responsible for the observed oxidative ability have been established by using Frontier molecular orbital (FMO) theory, natural bond orbital (NBO) analysis, etc., which include the reaction energy, the spin exchange effect, the spin-state conversion process, and the energy level of the lowest unoccupied molecular orbitals (LUMOs) of the reactive oxidants. The comparative oxidative abilities of the ruthenium-oxo/superoxo compounds with different axial ligands are also investigated. The results suggest that the ruthenium-oxo/superoxo species featuring a chlorine axial ligand is more reactive than that substituted with oxygen. This tuneable reactivity can be understood when considering the different electronic characters of the two ligands and the effective atomic number rule (EAN).

Do two oxidants (ferric-peroxo and ferryl-oxo species) act in the biosynthesis of estrogens? A DFT calculation.

Density functional theory calculations were performed in order to reveal the mysterious catalytic step of the biosynthesis of estrogens. The results indicated two reactive oxidants, ferric-peroxo and ferryl-oxo (compound I) species, to participate in the conversion of androgens to estrogens. The ferric-peroxo species was determined, according to our derived mechanism, to act in the oxidation of 19-OH androgen to yield the 19,19-gem-diol intermediate and generate the ferryl-oxo (compound I) species. This species was then modeled to effect, in the final step, an abstraction of H from an O-H group of 19,19-gem-diol to give the experimentally observed products. We considered our new mechanistic scenario to reasonably explain the latest experimental observations and to provide deep insight complementing the newly accepted compound I (Cpd I) mechanism.

GE11 peptide-conjugated nanoliposomes to enhance the combinational therapeutic efficacy of docetaxel and siRNA in laryngeal cancers.

In this study, dual therapeutic-loaded GE11 peptide-conjugated liposomes were developed and applied to enhance therapeutic efficacies of standard-of-care regimens for the treatment of laryngeal cancer. The therapeutic strategy used here was a combination treatment with the chemotherapeutic docetaxel (DTX) and siRNA against the ABCG2 gene that regulates multidrug resistance in many tumor types. Liposome-encapsulated DTX/ABCG2-siRNA molecules were targeted to recognize tumor cells of squamous morphology by conjugation to the EGFR-targeting ligand, GE11. Targeted, drug-infused liposomes were nanosized and exhibited controlled release of DTX. Presence of GE11 peptides on liposomal surfaces enhanced the quantities of liposomal constructs taken up by Hep-2 laryngeal cancer cells. GE11 peptide-conjugated liposomes also enhanced cytotoxic effects against Hep-2 laryngeal cancer cells when compared to treatment with free DTX, thereby reducing IC50 values. Additionally, GE11 peptide-conjugated liposomes had significantly increased anti-tumor and apoptotic effects. Treatments with the GDSL nanoparticle formulation inhibited tumor growth in Hep-2 xenograft-bearing nude mouse models when compared to treatments with non-targeted NP constructs. Treatment of the mouse models with GE11 peptide-conjugated liposomes mitigated toxicities observed after treatment with free DTX. Taken together, liposomal encapsulation of DTX and ABCG2-siRNA improved the anti-tumor effects of treatment with free DTX in Hep-2 cell lines, and conjugation of GE11 peptides to liposomal constructs enhanced anti-tumor efficacies and specificities in laryngeal cancer cells.

JMJD2A promotes the Warburg effect and nasopharyngeal carcinoma progression by transactivating LDHA expression.

BACKGROUND: Jumonji C domain 2A (JMJD2A), as a histone demethylases, plays a vital role in tumorigenesis and progression. But, its functions and underlying mechanisms of JMJD2A in nasopharyngeal carcinoma (NPC) metabolism are remained to be clarified. In this study, we investigated glycolysis regulation by JMJD2A in NPC and the possible mechanism. METHODS: JMJD2A expression was detected by Western blotting and Reverse transcription quantitative real-time PCR analysis. Then, we knocked down and ectopically expressed JMJD2A to detect changes in glycolytic enzymes. We also evaluated the impacts of JMJD2A-lactate dehydrogenase A (LDHA) signaling on NPC cell proliferation, migration and invasion. ChIP assays were used to test whether JMJD2A bound to the LDHA promoter. Finally, IHC was used to verify JMJD2A and LDHA expression in NPC tissue samples and analyze their correlation between expression and clinical features. RESULTS: JMJD2A was expressed at high levels in NPC tumor tissues and cell lines. Both JMJD2A and LDHA expression were positively correlated with the tumor stage, metastasis and clinical stage. Additionally, the level of JMJD2A was positively correlated with LDHA expression in NPC patients, and higher JMJD2A and LDHA expression predicted a worse prognosis. JMJD2A alteration did not influence most of glycolytic enzymes expression, with the exception of PFK-L, PGAM-1, LDHB and LDHA, and LDHA exhibited the greatest decrease in expression. JMJD2A silencing decreased LDHA expression and the intracellular ATP level and increased LDH activity, lactate production and glucose utilization, while JMJD2A overexpression produced the opposite results. Furthermore, JMJD2A could combine to LDHA promoter region and regulate LDHA expression at the level of transcription. Activated JMJD2A-LDHA signaling pathway promoted NPC cell proliferation, migration and invasion. CONCLUSIONS: JMJD2A regulated aerobic glycolysis by regulating LDHA expression. Therefore, the novel JMJD2A-LDHA signaling pathway could contribute to the Warburg effects in NPC progression.

Effects of Different Anesthetic Methods on Cellular Immune and Neuroendocrine Functions in Patients With Hepatocellular Carcinoma Before and After Surgery.

BACKGROUND: Many anesthesia methods have been studies in hepatocellular carcinoma (HCC). We aimed to explore the effects of combined intravenous and inhalation anesthesia and combined general and epidural anesthesia on cellular immune function and neuroendocrine function in patients with HCC before and after surgery. METHODS: Between September 2012 and April 2014, 72 patients who underwent a hepatectomy in our hospital were enrolled. RESULTS: Compared with the combined intravenous and inhalation anesthesia group, the combined general and epidural anesthesia group demonstrated increased CD4+ /CD8+ T cells 0 hr after surgery, increased CD3+ , CD4+ , CD4+ /CD8+ cells, and IFN-γ levels 12 hr after surgery, and increased CD3+ , CD4+ , and CD4+ /CD8+ cells 24 hr after surgery (all P < 0.05). At 72 hr after surgery, the levels of ACTH and Cor in the combined general and epidural anesthesia group, and the levels of CD3+ , CD4+ , CD4+ /CD8+ cells, and IFN-γ in both the combined intravenous and inhalation anesthesia and the combined general and epidural anesthesia groups decreased to pre-surgery levels. Significant differences were observed in the comparisons of CD3+ , IL-6, and IL-10 between the combined intravenous and inhalation anesthesia and the combined general and epidural anesthesia groups 72 hr after surgery (all P < 0.05). CONCLUSION: Our results revealed that combined general and epidural anesthesia plays a crucial role in hepatectomy via the mitigation of the inhibition of immunologic function in HCC patients during the perioperative period. Combined general and epidural anesthesia also hastens the recovery of immunologic suppression after surgery, which can provide a certain reference for the selection of clinical anesthesia in the treatment of HCC.

Two new nortriterpenoid saponins from Salicornia bigelovii Torr. and their cytotoxic activity.

Investigation of characteristic constituents of Salicornia bigelovii Torr. led to isolation of two new 30-nortriterpenoid glycosides, Bigelovii A (1), Bigelovii B (2), together with two known 30-nortriterpenoid glycosides 3-4 and three known oleanane-type triterpenoid glycosides 5-7. The structures of new compounds were elucidated by extensive 1D and 2D NMR, and MS spectroscopic analysis, and chemical evidences. All compounds were isolated for the first time from Chenopodiaceae. Thus compounds 1-4 were evaluated for their cytotoxicity and compouds 1, 3 showed moderate activity against four cell lines, HL-60 (promyelocytic leukemia), MCF-7 (breast carcinoma), HepG2 (liver carcinoma) and A549 (lung carcinoma), with IC(50) values of 6.18, 78.08, 13.64 and >100µM for 1; 31.87, >100, ~100, >100µM for 3, respectively.

[Study on the coumarin glucosides of Angelica dahurica].

OBJECTIVE: To study the coumarin glucosides of Angelica dahurica. METHODS: Fresh roots and rhizomes of Angelica dahurica were extracted with ethanol at room temperature. Repeated column chromatography and preparative HPLC were used to isolate and purify the compounds. Their structures were elucidated on the basis of chemical evidence and spectral analysis. RESULTS: Twenty-six coumarin glucosides were isolated from Angelica dahurica, while here we reported 7 of them: sec.-O-beta-D-Galactopyranosyl-(R)-byakangelicin (I);8-O-beta-D-Galactopyranosyl-xanthotoxol (II); 7-O-beta-D-Apiofuranosyl-(1-->6)-beta-D-Glucopyranosyl-peucedanol (III); (R)-peucedanol-7-O-beta-D-Glucopyranoside (IV); sec.-O-beta-D-Glucopyranosyl-(R)-Oxypeucedaninhydrate (V); 7-O-beta-D-Galactopyranosyl-Sco-poletin( VI); Aesculin (VII). CONCLUSION: Compound V is a new compound, Compound VII is isolated from Umbellifera for the first time, compounds III, IV are isolated from Angelica for the first time,while compound I, II and VI are isolated from this plant for the first time.

[Quantified research about the effects of sleep quality on attention in class and acadamic achievements in primary school children].

OBJECTIVE: To study the adverse effects of sleep problems and sleep insufficiency on attention in class and pupils' acadamic achievements. METHODS: A total of 1138 students from four primary schools at ages of 6-12 years were randomly sampled from four districts of Changsha city, Hunan Province June 2009 to April 2010. The inquired items included sleep problems, sleep time, sleep quality, attention in class and academic achievements. Teachers and parents observed the pupils according to the unified requirements for 3 months and then filled out the questionnaires. RESULTS: The total valid inquiry tables were 1091 with the answering rate of 95.87%, including 549 boys and 542 girls. The sleep quality was more poor in children with sleep problems or sleep insufficiency than in children with normal sleep. The sleep quality was reduced and aggravated along with the increasing sleep problems and the reducing sleep time. The attention in class and academic achievements in children with sleep problems or sleep insufficiency were more poor than in children with normal sleep. The sleep quality index was negatively correlated with attention in class and academic achievements. The attention in class was positively correlated with academic achievements. CONCLUSIONS: The decline in sleep quality directly affects the attention in class and reduce the academic achievements in primary school children.

Reaction mechanism of Cl2 and 1-alkyl-3-methylimidazolium chloride ionic liquids.

Systems containing 1-alkyl-3-methylimidazolium chloride ionic liquid and chlorine gas were investigated. Using relativistic density functional theory, we calculated the formation mechanism of trichloride and hydrogen dichloride anions in an Emim(+)Cl(-) + Cl(2) system. Emim(+)Cl(3)(-) forms without energy barriers. The more stable species ClEmim(+)HCl(2)(-) forms through chlorine substitution. Substitution of a H on the imidazolium ring is much easier than substitution on the alkyl side chains. Infrared, Raman, ESI-MS, and (1)H NMR spectra were measured for EmimCl, BmimCl, and DmimCl with and without Cl(2) gas. The coexistence of Cl(3)(-) and HCl(2)(-), as well as chlorine-substituted cations, was confirmed by detection of their spectroscopic signals in the Cl(2) added ionic liquids. Cl substitution appears less serious for cations with longer side chains.

[Studies on the chemical constituents of Salicornia europaea].

OBJECTIVE: To study the chemical constituents of Salicornia europaea. METHODS: The chemical constituents were isolated and purified by means of several chromatographic techniques and their structures were elucidated by spectroscopic methods. RESULTS: Five compounds were isolated and identified as syringaresinol 4-O-beta-D-glucopyranoside(1), icariside B2(2), erythro-1-(4-O-beta-D-glucopyranosyl-3,5-dimethyoxyphenyl)-2-syringaresinoxyl-propane-1,3-diol(3), longifloroside B(4), 7-O-beta-D-glucopyranosyl-6-methoxychromone(5). CONCLUSION: Compounds 1-4 are obtained from this genus for the first time.

Theoretical mechanism study of UF6 hydrolysis in the gas phase (II).

In our previous work (J. Phys. Chem. A 2008, 112, 8877.), we found theoretical evidence indicating UF5OH is an intermediate produced in the first step of UF6 hydrolysis. In this work, we explored the probable reaction channels starting from UF5OH + UF6 and UF5OH + UF5OH systems using relativistic density functional theory calculations. Initially, the two uranium containing species associate to form complex UF6.UF5OH or dimer (UF5OH)2 through hydrogen bonding. The energy released is 12-16 kcal/mol, which may promote further reactions. After H2O or HF are eliminated from the complex or dimer, compounds containing U-O-U bond are produced. These compounds are potentially feasible to associate into larger clusters or solidify. Relative to the isolated initial species, the energies of the final products are -6 to -13 kcal/mol lower, indicating that the reactions may spontaneously proceed. The calculated IR spectra features can be used to indicate the formation and interaction type of the intermediates and products.

Theoretical mechanism study of UF6 hydrolysis in the gas phase.

The mechanism of the gas-phase reaction UF 6 + H 2O --> UOF 4 + 2HF is explored using relativistic density functional theory calculations. Initially, H 2O coordinates with UF 6 to form a 1:1 complex UF 6.H 2O. Over an activation energy barrier of about 19 kcal/mol, H 2O transfers a H atom to a nearby ligand F, resulting in UF 5OH + HF. The eliminated HF or another H 2O molecule may form a hydrogen bond with UF 5OH. Starting from UF 5OH, the second HF elimination results in UOF 4. If UF 5OH is in the isolated form, UF 5OH --> UOF 4 + HF takes place over a barrier of 24 kcal/mol. If UF 5OH is hydrogen-bonded with H 2O or HF, the conversion barrier is less than 10 kcal/mol. Once formed, the unstable UOF 4 tends to associate with additional ligands and hydrogen-bonding donors. The calculated binding energies indicate the significance of such interactions, which may have profound impact on further HF eliminating reactions. The IR spectra features can be used to indicate the formation and interaction type of the intermediates and products.