Search

A rapid and sensitive high-performance liquid chromatography-high-resolution orbitrap mass spectrometry method was developed for the simultaneous screening of 354 organic poisons and metabolites in blood and urine, including drugs, medications, pesticides, rodenticides, veterinary drugs, alkaloids, and mycotoxins with a multi-toxicant chromatography-mass spectrometry information library. The method and library showed good prospects in clinical poisoning screening and forensic toxicological identification. Blood and urine samples were extracted successively with ethyl acetate in acidic and alkaline conditions; then, the extract was blown to nearly dry by nitrogen gas and redissolved with methanol-aqueous solution (v:v, 50:50), and the dissolved solution was analyzed by LC-MS/MS after filtering. Precursor ions' m/z was set for identification, retention time, fragment ions, and isotopic pattern which were used for confirmation. No interference peaks were found in the blank samples, showing good specificity. The LODs of toxicants in urine and blood were 1.00×10

Objective To evaluate the improvement of motor, anxiety, and depression in patients with blepharospasm with the use of botulinum toxin type A (BTX-A) and repetitive transcranial magnetic stimulation (rTMS). Methods A total of 63 BEB patients accompanied by anxiety/depression were enrolled, among which 28 patients were treated with the injection of botulinum toxin type A (BTX-A) alone, while 35 patients were treated with BTX-A injection combined with rTMS. All patients were followed up for 6 months, and the overall efficacy was evaluated. Results BTX-A alone treatment and combined rTMS treatment could both significantly improve the symptoms of patients, and the effective rate was 92.86% and 94.29%, respectively. The duration of efficacy was significantly longer in the combined rTMS treatment group (16.89±3.39 weeks) than in BTX-A treatment group (13.04±3.48 weeks). After treatment, SDS score of BTX-A treatment group and combined rTMS treatment group was 49.69±7.90 and 49.46±6.73, respectively, and there was no significant difference between the two treatment groups; SAS score of BTX-A treatment group and combined rTMS treatment group was 53.88±7.34 and 48.79±6.62, respectively, and there was significant difference between the two treatment groups. Conclusion Compared to BTX-A alone treatment, BTX-A combined with rTMS can effectively improve the effect of BTX-A, prolong the duration of blepharospasm relief, and significantly reduce depression and anxiety in patients with BEB.

To establish a method for determination of the common and emerging halogenated carboxylic acids(HCAs) in drinking water by ion chromatography(IC) and quadrupole-orbitrap(Q-Orbitrap) high resolution mass spectrometry(HRMS) combined the traditional quantitative detection with semi-target analysis.Effects on the type of chromatographic column, the composition of mobile phase, the flow rate of acetonitrile added post column, the column temperature, and the injection volume were studied in detail for IC-HRMS method, also for HRMS conditions. Drinking water sample was directly injected into IC-HRMS for analysis after filtration. The chromatography separation was performed on an AS21 anion exchange chromatography column(2 mm×250 mm) with the gradient elution using 800 mmol/L methylamine-water as mobile phase, and acetonitrile was added after column. The detection was conducted on HRMS with the electrospray ionization negative mode. And the quantitative analysis of 8 haloacetic acids(HAAs) and semi-target screening of 19 HCAs were achieved by full MS/dd-MS~2 mode.Good linearity(rgt;0.996) was obtained for each of 8 HAAs for IC-HRMS. The method detection limits(MDLs) and method quantification limits(MQLs) were in the range of 0.50-2.5 μg/L and 1.7-8.3 μg/L, respectively. Intra-and inter-day relative standard deviations(RSDs) were in the range of 1.50%-11.0% and 4.58%-10.9%, respectively. The recoveries were in the range of 61.3%-117%(n=6). The proposed method was applied to analyze 39 drinking water samples, and dichloroacetic acid and trichloroacetic acid were detected and quantified, with concentrations ranging from 1.35 to 48.0 μg/L. Besides, five HCAs(difluoroacetic acid, trifluoroacetic acid, bromochloroacetic acid, monochloropropionic acid and dichloropropionic acid) were preliminary identified with semi-target screening method.The developed method was simple, rapid, no sample preparation except filtration and low reagent cosumption, which could meet the need of drinking water monitoring and achieve comprehensive screening of HCAs in drinking water. In addition, full MS/dd-MS~2 data acquisition mode could provide retrospective analysis of existing data by adding the emerging or interesting HCAs into the screening compound database.

An ensemble-based method for the observation system simulation experiment (OSSE) is employed to design optimal observation stations and assess the present observation stations in the northeastern South China Sea (SCS). We employed the 20-year (1992–2012) sea surface height (SSH) data to design an array to monitor the intraseasonal to interannual variability. The results show that the most key region was found located at the northwest of Luzon Island (LI) where the energetic Luzon cyclonic gyre (LCG) occurs; other key regions include the edge of the LCG, the northwest of the Luzon Strait (LS), and the southwest of Taiwan, China. By contrast, we found that the present observation stations might oversample at the northwest of the LS and undersample at the northwest of LI. In addition, the optimal stations perform better in a larger area than the present stations. In vertical direction, the key layer is located within the upper 200-m depth, of which the surface and subsurface layers are most valuable to the observing system.

CdS/Zn2GeO4 (CG) composites were synthesized through the simple hydrothermal process. The crystal structure, morphology and light absorption property of the products were studied in detail. The CG composites showed excellent photocatalytic hydrogen production performance upon visible light illumination. Especially, the CG-3 composite displayed the highest H2 evolution rate of 1719.8 μmol h−1 g−1, which was about 3.80 and 4.28 times higher than the pure CdS and Zn2GeO4. Besides, the cyclic stability of the CG-3 composite was also excellent. The PL, photocurrent response and EIS spectra results testified that the efficient separation and transfer of photoinduced charge carriers achieved between CdS and Zn2GeO4, which could result in the promotion of photocatalytic performance. Moreover, a possible mechanism of H2 generation over CdS/Zn2GeO4 heterojunction was discussed. The practicable way to construct heterojunction composites would be helpful for the design of other systems with excellent photocatalytic property.

A simple and sensitive method for analysis of 1-OHP-G in urine to evaluate PAHs exposure was established. The urine was extracted with a OASIS PRiME HLB column, and the eluent was directly injected into HPLC–FLD for analysis. The separation was carried out on a ACQUIIY UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm), using methanol–1.5% formic acid water (60:40, v:v) as mobile phase at the flow rate of 0.2 mL/min. 1-OHP-G was detected at the excitation wavelength of 338 nm and the emission wavelength of 379 nm. Good linearity was obtained from 0.010 to 5.0 ng/mL for 1-OHP-G. The limit of detection of 1-OHP-G was 0.0032 ng/mL and the limit of quantification was 0.010 ng/mL. The intra-day and the inter-day precisions were 1.68, 4.98 and 1.81%, 5.00% at the concentrations of 0.010 ng/mL and 5.0 ng/mL, respectively. The proposed method was applied for urine sample analysis and the whole procedure could be completed within 8 min with the recoveries of 91.9–109%, 92.7–107% and 94.5–107% at the concentrations of 0.010 ng/mL, 1.0 ng/mL and 5.0 ng/mL, respectively. The results of 41 urine samples from non-professionals measured with the proposed method and UPLC–MS/MS were compared by Bland–Altman test and Passing–Bablok regression, showing a good agreement between the two methods. Moreover, dynamic change of urinary 1-OHP-G after eating barbecued food was detected by the proposed method and the results were consistent with the reported researches about 1-OHP. The proposed method was simple and rapid, and it could also to meet the assessment of population exposure to PAHs with high sensitivity and accuracy.

Maternal exposure to benzene and related compounds, trichloroethylene, and polycyclic aromatic hydrocarbons has been suggested as risk factors for reproductive and developmental problem. In different countries and groups, there are differences in socioeconomic circumstances, consumer products, dietary habits, lifestyles, and so on, resulting in different exposure risks from these chemicals. This study investigated the correlation between their metabolite concentrations and socioeconomic, demographic, and dietary factors to explore the possible exposure source of the concerned pollutants in pregnant women. We conducted biological monitoring to assess the exposure of these chemicals using urine samples from 590 to 639 pregnant women during 2nd or 3rd trimester of pregnancy in six cities of China. Socioeconomic and demographic characteristics and dietary habits were collected from questionnaires. The detection rate was over 74% of the urine samples for all metabolites. Compared with the Fourth National Report on Human Exposure to Environmental Chemical concentrations for females (FNRHEEC, the US Centers for Disease Control and Prevention), the metabolite concentrations of benzene compounds and trichloroethylene, excluding MA reported here, were higher. Principal component analysis results showed that SBMA and MHA could be proxy of the principal sources of metabolites for benzene compounds. The concentrations of SBMA and MA were higher in Fuzhou and Wuhan, respectively. The concentration of DCVMA was higher in Shenzhen, Xi'an, and Nanning, and the concentration of PGA was higher in Fuzhou, Wuhan, and Xi'an. Also, the 1-OHPG concentration in Wuhan is higher than that in Fuzhou and Shenzhen. Unhealthy dietary habits, using cosmetics and indoor exposure, contacting chemical solvent during pregnancy were associated with increased benzene compounds, trichloroethylene, and PAH exposure. There were significant positive associations between 1-OHPG level and maternal BMI, low education status, and cooking without a range hood. Pregnant women in China may be at a greater risk of exposure to most of the target compounds than US females, and their exposure levels varied in different regions. Some adverse environmental and behavioral factors may increase the exposure of environmental toxins, which can urge people to take measures to reduce the health risk to pregnant women during pregnancy.

Bisphenol analogues, amphenicol antibiotics, and phthalate have widely aroused public concerns due to their adverse effects on human health. In this study, a rapid and sensitive method for determination of nine bisphenol analogues, three amphenicol antibiotics, and six phthalate metabolites in the urine based on ultra-high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry was developed and validated. The sample pretreatment condition on the base of mixed-mode anion-exchange (Oasis MAX) SPE was optimized to separate bisphenol analogues and amphenicol antibiotics from phthalate metabolites: the former were detected with a mobile phase of 0.1% ammonium water solution/methanol containing 0.1% ammonium water solution in negative mode, whereas the latter were determined with a mobile phase of 0.1% acetic acid solution/acetonitrile containing 0.1% acetic acid in negative mode. The limits of detection were less than 0.26 ng/mL for bisphenol analogues, 0.12 ng/mL for amphenicol antibiotics, and 0.14 ng/mL for phathalate metabolites. The recoveries of all target analytes in three fortification levels ranged from 72.02 to 117.64% with the relative standard deviations of no larger than 14.51%. The matrix effect was adjusted by isotopically labeled internal standards. This proposed method was successfully applied to analyze 40 actual urines and 13 out of 18 studied compounds were detected. Graphical abstract Simultaneous determination of nine bisphenol analogues, three amphenicol antibiotics, and six phthalate metabolites in human urine samples.

Perfluorooctanoic acid (PFOA) in environmental media contains numerous isomers/enantiomers because of the PFOA manufacturing process and biological degradation of PFOA precursors. Few methods for analyzing PFOA enantiomers have been described. A simple derivatization method using (S)-1-phenethyl chloride that was developed to allow PFOA isomers/enantiomers to be separated by gas chromatography and analyzed by electron-capture negative ionization mass spectrometry is described here. PFOA standards were analyzed, and enantiomers of the chiral isomers perfluoro-3-methyl-heptanoic acid, perfluoro-4-methyl-heptanoic acid, and perfluoro-3,5-dimethyl-hexanoic acid were separated using an HP-5MS column. Linear PFOA and perfluoro-6-methyl-heptanoic acid were chromatographically separated from these enantiomers. The linear ranges (giving correlation coefficients r > 0.997) of the calibration curves for the isomers were 0.010–3.00 ng/mL. PFOA isomer/enantiomer concentrations in river water were determined using the method. The method separated the enantiomers of perfluoro-3-methyl-heptanoic acid and perfluoro-4-methyl-heptanoic acid, the isomers of perfluoro-6-methyl-heptanoic acid, and linear PFOA in river water. No significant differences were found between the PFOA enantiomer/isomer compositions of the sample and technical PFOA. Enantiomer ratios can provide information about the sources and transport of pollutant isomers/enantiomers in the environment. Enantiomeric separation requires effective separation techniques. Our method achieved chiral separation using a non-chiral GC column that is often used in general analytical laboratories. The method could be used to investigate the sources and fates of PFOA and the isomers/enantiomers of other potentially toxic persistent pollutants in the environment and the risks posed to humans.

Phosphodiesterase type 5 (PDE5) inhibitors are first-line therapy for pulmonary arterial hypertension (PAH) and erectile dysfunction. As a continuing work to improve the terminal half-lives and oral bioavailabilities of our previously reported 4(3 H)-pyrimidones, a pharmacokinetics-driven optimization focusing on the terminal substituent is described. Two major congeneric series of 4(3 H)-pyrimidones, the aminosulfonylphenylpyrimidones and acylaminophenylpyrimidones, were designed, synthesized, and pharmacologically assessed in vitro and in vivo. Among them, compound 15 (TPN171) with subnanomolar potency for PDE5 and good selectivity over PDE6 was finally recognized as a potential drug candidate, and its pharmacokinetic profiles in rats and dogs are significantly improved compared to the starting compound (3). Moreover, TPN171 was proven to exert a longer lasting effect than sildenafil in animal models, providing a foundation for a once-daily oral administration for its clinical use. TPN171 is currently being investigated in a phase II clinical trial for the treatment of PAH.

Urinary cotinine and NNAL are the biomarkers of tobacco smoke exposure and tobacco specific nitrosamines (TSNAs), respectively. A new method for the simultaneous analysis of them by hydrophilic interaction liquid chromatography tandem mass (HILIC-MS/MS) combined with PRiME HLB solid phase extraction (SPE) was developed. The sample matrix was removed effectively with PRiME HLB SPE and HILIC separation. The linearities were good in a range of 5.00-3.00 × 103 ng/L for NNAL and 0.200-4.00 × 102 μg/L for cotinine. The method detection limit of NNAL (0.0580 ng/L) was better than that in other literatures, and 0.0240 μg/L for cotinine. Recoveries were 91.6-110% and 88.7-113% with relative standard deviations of 3.78-9.12% and 0.120-1.15% for NNAL and cotinine, respectively. 29 urine samples were detected by the established method. The contents of NNAL and cotinine were 0.590-66.7 ng/g·Cr and 2.86-1.34 × 103 μg/g·Cr, respectively. Moreover, the results showed that urinary NNAL and cotinine were significantly positive correlation, even in passive smokers.

A new and simple one-pot hydrothermal method was used for the preparation of ZnO/Zn2GeO4 (ZG) composites. Cu was subsequently loaded on ZG-2 composites by an impregnation method to obtain ternary ZG-2-Cu photocatalysts. The ZG-2-5%Cu composite showed optimum photocatalytic water splitting (H2 production) performance under simulated sunlight illumination. Cu sedimentation enhanced light absorption and prevented electron–hole pair recombination. The photoinduced electrons are believed to migrate from the conduction band (CB) of ZnO and Zn2GeO4 to Cu, allowing fast separation of the photogenerated electrons and holes. The facile synthesis and the excellent photocatalytic performance of ZG-2-5%Cu make it a good material to conduct the H2 evolution reaction.

A method for the determination of urinary nicotine and cotinine by solvent demulsification-dispersive liquid–liquid microextraction (SD-DLLME) combined with hydrophilic interaction chromatography tandem mass spectrometry (HILIC-MS/MS) was established. The chromatographic separation was performed on an ACQUITY UPLC® BEH HILIC column with an isocratic elution in which methanol and 0.1% ammonia (v/v) were used as the mobile phase. Identification was conducted using tandem mass spectrometry with electrospray ionization in positive mode. Working calibration curves were plotted for quantification determination. DLLME conditions were optimized with the orthogonal array design (OAD). The microextraction was performed with 100 μL trichloromethane as the extracting solvent and 1000 μL methanol as the dispersing solvent. In addition, the pH value of the sample solution was adjusted to 9.0 for good extraction efficiencies. 800 μL acetone was selected as the demulsification solvent to facilitate the phase separation between the sample solution and extractant. The method detection limits of nicotine and cotinine were 0.0025 μg L−1 and 0.0020 μg L−1 respectively. Besides, during the sample preservation, it was proved that 1% (w/v) of sodium hydrogen sulfate in the sample can prevent analyte degradation. The established method was applied to analyze 516 urine samples. The method was simple, sensitive and accurate, and it also meets the requirement of evaluating human tobacco exposure, especially for the nonsmoking population.

A method of binary mixed solvent-based solvent demulsification dispersive liquid-liquid microextraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples. A binary mixed solvent of methylene chloride and n-hexane (v/v = 1 : 1) which has a lower density than water was used as the extraction solvent, obtaining satisfactory extraction efficiencies for PAHs, and also allowing convenient operation. Acetonitrile as the dispersive solvent was injected into the water sample solution to form an emulsion. The extraction can be completed in 5 min and ethanol was used as the demulsification solvent to bring about successful phase separation without centrifugation. Coupled with GC-MS/MS analysis, the method was simple, sensitive, accurate and suitable for batch analysis of PAHs in water samples. Good linearity was obtained within the linear range for 16 PAH compounds, with determination coefficients from 0.9980 to 0.9998. This method can be used to effectively evaluate the situation of PAH pollution in water intended for human consumption and environmental water, the method detection limits (MDLs) of which were 2.1 to 13.6 ng L−1 and only 20 mL of water samples were used for analysis. The proposed method was applied to determine PAHs in actual water samples including tap water, and the upper, middle and lower reaches of the Jinjiang river in Chengdu city. Meanwhile, spiked samples and procedural blanks were used for quality control measurements according to ISO/TS 13530-2009 to guarantee the accuracy of this method. The average spiked recoveries of PAHs were in the range of 85.0–104% with RSDs in the range of 5.8–10.9%. Naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene and pyrene were predominantly measured, and PAH pollution was found at the total concentrations of 0.162–0.206 μg L−1 in the Jinjiang river of Chengdu city of P. R. China. Considering their toxicity, attention should be paid to water pollution by PAHs and necessary monitoring should be done.

The glucuronide conjugate of 1-hydroxypyrene (1-OHP-G) is a sensitive and reliable index biomarker for assessing low exposure to polycyclic aromatic hydrocarbons (PAHs). A simple method for determining 1-OHP-G in human urine with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established and applied to evaluate the exposure level of PAHs of pregnant women in a large sample size. After the urine sample was extracted with ethyl acetate, 0.2 mL of the aqueous phase was diluted to 1.0 mL with 5 mmol/L ammonium acetate before injection. The chromatographic separation was performed on a C18 column with a gradient elution and identification was conducted on a tandem mass spectrometry with electrospray ionization in negative mode. 1-OHP-d9-G was used as an internal standard to improve precision. The method was validated and good linearity was obtained in the range of 0.1∼2.0 ng/mL. The limit of detection (LOD) and the limit of quantification (LOQ) of 1-OHP-G were 0.015 and 0.051 ng/mL. Intra-day and inter-day precision were 4.3 and 6.7 %, respectively. The spiked recoveries were 79.4∼106 % for urine samples. This method was rapid, sensitive, and very suitable for batch analysis of urine. Six hundred seventy-five urine samples of pregnant women from the cities of Fuzhou, Shenzhen, and Nanning of P.R. China were analyzed with the proposed method. The medians of 1-OHP-G concentration were 0.27 μg/g.cr (n = 201), 0.30 μg/g.cr (n = 212), and 0.51 μg/g.cr (n = 262) for the cities of Fuzhou, Shenzhen, and Nanning, respectively. 1-OHP-G concentrations in urine samples of pregnant women from the cities of Fuzhou and Shenzhen in coastal areas were both significantly lower than that of Nanning City in inland region (p < 0.001).

Effective decomposition of antibiotic sulfadiazine (SD) in a Fe0-catalyzed sonochemical Fenton like system (Sono-FL) was demonstrated. By using the response surface methodology (RSM), an optimized experimental condition of pH 7.00, 0.94 mM Fe0, 1.90 mM persulfate (PS) and 20 W ultrasound (US) power was concluded, which could reach the predicted SD degradation efficiency of 90%. Afterwards, effects of wastewater matrix (five inorganic anions and two chelating agents) on the SD degradation were investigated in the system, respectively. It was found that the SD degradation could be inhibited by SO42−, NO3−, HCO3−/CO32− and H2PO4− to different extents. Cl− would lead to an enhancement with a low dosage (5 mM), but an inhibition with a high dosage (100 mM). Unexpectedly, chlorinated organic intermediates were also found as SD decomposed. Appropriate dosages of oxalic acid (OxA) or EDTA could benefit the SD degradation in the Sono-FL system, while excessive chelating agents would play as competitive pollutants. It was summarized that inorganic anions would mainly react with SO4 − and/or OH to form sub-radicals of less oxidative potential. OxA and EDTA would not only participate in complexing dissolution of Fe0 but also provide additional oxidants such as H2O2 and [FeIVO]2+, through the electron transfer reactions caused by the iron-ligands species.

A new kind of solid solution (CdxZn2-xGeO4) was prepared using the facile hydrothermal method for the first time. The crystal structure, morphology and light absorption property of the products were studied systematically. Compared with pure Zn2GeO4, CdxZn2-xGeO4 solid solutions had narrower band gap and were able to respond to wider range of the sunlight. Upon simulated sunlight irradiation, the hydrogen evolution activities of CdxZn2-xGeO4 solid solutions were much higher than that of the pure Zn2GeO4. Furthermore, the highest H2 generation rate (15.00 mmol g−1 h−1) was achieved over the Cd1.0Zn1.0GeO4, which was approximately 24.2 times higher than that of pure Zn2GeO4 (0.62 mmol g−1 h−1). The PL, EIS and photocurrent measurements proved the fast transfer and rapid seperation of electron-hole pairs were succeeded in Cd1.0Zn1.0GeO4, which led to the promotion of the photocatalytic activity. The feasible way to synthesize solid solutions could be useful in the design of other systems with excellent photocatalytic performance.

A method for analysis of 22 kinds of elements in umbilical cord serum by inductively coupled plasma mass spectrometry( ICP-MS) was developed.The serum samples were taken out and diluted 15 times with 2% HNO3. After centrifugation for 5 min at 5000 r/min, the supernatant was injected into ICP-MS for analysis. Ge was used as internal standard element for correcting analysis of octopole collision model( Fe, As, Se, I) and Sc, Ge, In, Bi were for standard model. ICP-MS analysis was performed on 1550 W of RF power, 15. 00 L/min of plasma gas flow rate, 0. 30 mL/min of sample injection volume and 90 ms of residence time. Octopole collision was carried out with He as reaction gas at 1. 0 L/min, 150 V of octopole RF power and5. 0 V of energy discrimination.Internal standard curves were plotted for quantitative analysis and good linearity was obtained in their linear range( r0. 9993)and the limits of detection were 0. 00158-1. 21 μg/L. Control serum was analyzed withthe proposedmethod and theresult were in accordance with the standard values. The proposed method was applied to analysis of umbilical cord serum and the spiked recoveries were 86. 4%-116% with RSD of 0. 164%-18. 79%( n = 6).ICP-MS is rapid, sensitive, accurate and simple. It can effectively determine the concentration of the elements in serum.

A coralline-like lithium-rich layered cathode material with homogeneous composition of Li 1.20 Mn 0.54 Ni 0.13 Co 0.13 O 2 has been successfully synthesized via a facile ethanolamine (EA)-mediated hydrothermal method route, with subsequent calcination at 850 °C. An initial specific discharge capacity of 250.2 mAh g −1 and a reversible specific capacity of 210.2 mAh g −1 after 100 cycles at a constant density of 25 mA g −1 (1 C = 250 mA g −1 ) are acquired. Even at 10 C, it still delivers a discharge capacity of approximately 100 mA h g −1 , thereby indicating its excellent high power performance. The sample also shows enhanced cycling performance with 88.5%, 79.9% and 90.5% of capacity retention after 100 cycles at 0.5, 5 and 10 C rates, respectively. Besides, 84.5% of initial capacity is retained even after 200 cycles at 10 C. Consequently, the fascinating electrochemical performance may facilitate the coralline-like LMNCO composite to be a promising alternative cathode for LIBs with a high application potential.

Modified porous spherical Li1.2Mn0.534Ni0.133Co0.133O2 has been successfully synthesized via a co-precipitation method, adopting graphene and carbon nanotube conductive liquid (GNL) as a template and surface modified material. The unique porous structure and the larger specific surface area of the porous Li1.2Mn0.534Ni0.133Co0.133O2 contribute to both the increase in the first coulombic efficiency, from 76.3% to 82.0%, and the enhancement of the rate capability, demonstrating initial discharge capacities of 276.2, 245.8, 218.8, 203.9, 178.8, 135.9 and 97.5 mA h g−1 at different discharge rates of 0.1, 0.2, 0.5, 1.0, 2.0, 5.0 and 10 C, respectively. Even after suffering 100 cycles of charge–discharge, the porous Li-rich cathode can still deliver a discharge capacity of 235.5 mA h g−1, suggesting a high capacity retention of 86.2% compared to the initial discharge capacity (273.3 mA h g−1). Besides, the diffusion coefficient of the Li+ investigated by the cyclic voltammetry technique is approximately 10−12 cm2 s−1, indicating faster kinetics of the lithium ions for the modified porous Li1.2Mn0.534Ni0.133Co0.133O2 compared with the ordinary Li1.2Mn0.534Ni0.133Co0.133O2 (∼10−13 cm2 s−1). In fact, the introduction of GNL as a template not only leads to the porous structure of the Li-rich cathode material but also brings about improvement to the crystallinity and size of the grains, which can be ascribed to the combined effect of the GNL with the carbonate precursors of MCO3 (M = Mn, Ni, Co) during the recrystallization process.

The abasic site is one the most common DNA lesions formed in cells; it induces a severe blockage of DNA replication and is highly mutagenic. We continue to use Gp90 exo–, the sole DNA polymerase from Pseudomonas aeruginosa phage PaP1, to study DNA replication upon encountering an abasic site lesion. Gp90 exo– can incorporate dNTPs opposite the abasic site, but extension past this site is extremely slow. Among the four dNTPs, dATP is preferentially incorporated opposite the abasic site, consistent with the A-rule. The incorporation is independent of the identity of the nucleotide 5′ of the abasic site. The incorporation of dATP opposite the abasic site occurs by direct incorporation of dNTP opposite the abasic site without a −1 frameshift deletion. Extension from an A:abasic site pair by Gp90 exo– is slightly unfavorable relative to those from other abasic site pairs. Incorporation of dATP opposite the abasic site is preferential and shows a biphasic shape, indicating that this incorporation is much faster...

ClpXP protease is an important proteolytic system in Salmonella enterica serovar typhimurium (S. typhimurium). Inactivation of ClpXP by deletion of clpP resulted in overproduction of RpoS and a growth defect phenotype. Only one report has indicated that deleting rpoS can restore the growth of a S. typhimurium clpP mutant to the wild-type level. Whether overproduction of RpoS is responsible for the growth deficiency resulting from clpP disruption and how ClpXP affects the cell metabolism of S. typhimurium remain to be elucidated. The aim of this study is to investigate the effect of ClpXP on cell metabolism of S. typhimurium and explore the possible co-effect of RpoS associated with ClpXP in cell metabolism. We constructed a clpP rpoS double deletion mutant TT-19 (ΔclpP ΔrpoS TT-1) using a two-step phage transduction technique. We then compared the metabolite fingerprints of Salmonella rpoS deletion mutant TT-14 (ΔrpoS TT-1), clpP deletion mutant TT-16 (ΔclpP TT-1), and clpP rpoS double deletion mutant TT-19 (ΔclpP ΔrpoS TT-1) with those of the wild-type strain TT-1 by using gas chromatography coupled with mass spectrometry (GC–MS). Deletion of rpoS recovered only a part of the growth of Salmonella clpP mutant. Further metabolome analysis indicated that clpP disruption changed the levels of 16 extra- and 19 intracellular substances, while the extracellular concentrations of 4 compounds (serine, l-5-oxoproline, l-glutamic acid, and l-tryptophan) and intracellular concentrations of 10 compounds (l-isoleucine, glycine, serine, l-methionine, l-phenylalanine, malic acid, citric acid, urea, putrescine, and 6-hydroxypurine) returned to their wild-type levels when rpoS was also deleted. ClpXP affects the cell metabolism of S. typhimurium partially in an RpoS-dependent manner.

The analytical method of nicotine and cotinine in human urine with hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) was established. After the urine sample containing nicotine-d4 and cotinine-d3 isotope internal standards being diluted with water, the filtrate was introduced into ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for analysis. Separation was performed on an ACQUITY UPLC® BEH HILIC column (50 mm×3.0 mm, 1.7 μ m), in which methanol and 0.1% (v/v) ammonia were used as the mobile phases with isocratic elution at 0.2 mL/min of flow rate. Positive ion scan mode was used for mass spectrometry measurement and calibration curves were plotted for quantification determination. A good linearity could be obtained in the range of 1.0-1000 μ g/L for nicotine and cotinine with the linear coefficients of 0.9949 and 0.9958, respectively. The limits of detection of nicotine and cotinine were 0.082 μ g/L and 0.077 μ g/L, and the limits of quantification were 0.27 μ g/L and 0.26 μ g/L, respectively. The recoveries of the spiked urine samples were 90.4%-103.5% and 93.0%-104.6%, and the relative standard deviations (RSDs) were 4.80%-6.21% and 4.22%-7.15% for nicotine and cotinine respectively. The established method was applied to the analyis of 200 urine samples. Based on the investigation information of the urine of the smoking people, the nicotine contents were 26.68-854.30 μ g/L, and the cotinine contents were 36.66-1191.18 μ g/L (n=86, Mnicotine=76.00 μ g/L, Mcotinine=83.52 μ g/L, M:median); of the nonsmoking people, the nicotine contents were 5.08-69.66 μ g/L, and the cotinine contents were 3.16-28.21 μ g/L (n=114, Mnicotine=7.53 μ g/L, Mcotinine=3.79 μ g/L). The method is simple, sensitive and rapid. It is suitable for batch analysis of nicotine and cotinine in urine, and it can meet the requirement of evaluating the human tobacco exposure.

A method of vortex-assisted dispersive liquid-liquid extraction coupled with gas chromatography and tandem mass spectrometry for the determination of nicotine and cotinine in urine was developed. Response surface methodology was applied to obtain the optimum extraction conditions. In this method, Plackett-Burman design was utilized to evaluate the impact of five selected factors on pretreatment procedure. Then, three main factors were optimized using a Box-Behnken design. The optimized method showed good linearities at 1-2000 μg/L with correlation coefficients of 0.9998 for nicotine and 0.9986 for cotinine. Recovery was 91.4-106 and 91.7-108% for nicotine and cotinine, respectively. The intraday relative standard derivations of determination were 1.47-4.06% for nicotine and 0.41-3.16% for cotinine, and interday relative standard derivations were 3.03-6.70% for nicotine and 1.64-6.38% for cotinine. The method detection limits for nicotine and cotinine were 0.33 and 0.34 μg/L, respectively. A total of 87 urine samples from smokers and nonsmokers were tested with the proposed method. Urinary nicotine and cotinine were 23.0-6.67 × 103 and 18.4-4.17 × 103 μg/(g·cr) for smokers and 1.31-286 and 1.39-131 μg/(g·cr) for nonsmokers, respectively. The method is sensitive, suitable and reliable for the determination of nicotine and cotinine in urine and meets the requirements for evaluating short-term tobacco exposure.

In this study, a novel ultrasound-enhanced heterogeneous Fe 0 /persulfate (US/Fe 0 /PS) system was developed and investigated for the degradation of an antibiotic sulfadiazine (SD). It was demonstrated that the US/Fe 0 /PS system could achieve a significant synergy in the degradation efficiency of SD, as compared to its corresponding comparative systems. The SD degradation in the US/Fe 0 /PS system could be applied by the pseudo-first-order kinetic with a k obs (SD) value of 3.4 ± 0.20 h −1 . Affecting factors such as initial pH, dosage ratio of [Fe 0 ]:[PS], US input power and reaction temperature were further studied. SD could be effectively degraded with a relatively low PS dosage at a broad pH range of 3–7. Simultaneous evolution of soluble iron species and PS was evaluated in three comparative systems (US/Fe 0 , Fe 0 /PS and US/Fe 0 /PS) during the reaction. It could be concluded that the promotional role of US would be dual in the US/Fe 0 /PS system, i.e. enhancement in the heterogeneous iron corrosion reactions and acceleration in the bulk radical reactions. Identification of the degradation intermediates indicated that sulfate radical (SO 4 − ) oxidation was the main SD degradation pathway. Attacking of the amine group in the benzene ring would be its first step, followed by cleavage of C–N bonds in the heterocyclic ring. Another degradation pathway, i.e. direct cleavage of the S–N bond should be also present.

As an anode material in lithium ion battery, the Sn-Co/C composite electrode materials have been successfully synthesized by hydrothermal and sol-gel methods, respectively. The resultant composites were mainly composed of Sn-based oxides, nanometer Sn-Co alloy and carbon. Carbon and Co, acting as buffer materials, can accommodate to the large volume change of active Sn during the discharge-charge process, thus improving the cycling stability. Although charge/discharge curves revealed the excellent cycle performance for samples synthesized by both methods, composites obtained by the sol-gel showed a better dispersion effect of nanoparticles on the carbon matrix and possessed much more improved stable capacity with ~624.9 mAh g−1 over 100 cycles and that by hydrothermal method only exhibited ~299.3 mAh g−1. Therefore, the Sn-Co/C composites obtained by sol-gel synthesis method could be a perfect candidate for anode material of Li-ion storage battery.

Li-rich layered cathode materials Li1.13[Ni0.233Mn0.534Co0.233]0.87O2 are successfully synthesized by a co-precipitation method with hexadecyl trimethyl ammonium bromide (CTAB) as a surfactant. The structural and electrochemical feature changes of the resulting cathode materials have been studied thoroughly. When CTAB is considered as a surfactant, well-crystallized Li-rich layered cathode materials are obtained with Li2CO3 treatment for the festoon-like precursor hierarchically assembled by nanoplates. Among these oxides, the sample synthesized with CTAB shows a stable mixed phase on the edge of the powder particles and exhibits excellent electrochemical performance. The product delivers the highest initial discharge capacity of 394 mA h g−1 at 0.1 C (1 C = 200 mA g−1) between 2.5 and 4.8 V and 84.1% capacity is retained after 100 cycles. It is considered that the higher capacity and superior rate capability would be ascribed to the activation effect of CTAB, which can form a stable mixed structure and thus effectively alleviate the layered/spinel structure change during cycling.

The aim of our study was to evaluate the pathological features of posterior echo attenuation of papillary thyroid microcarcinoma (PTMC) and cystic degeneration of cervical lymph node metastasis. We retrospectively evaluated the ultrasound results from 36 cases of PTMC with 20 nodules of cystic degeneration of cervical lymph node metastasis and correlated the results with the histopathologic findings. The preliminary study indicated certain correlation between histopathologic findings and ultrasound results of posterior echo attenuation of papillary thyroid microcarcinoma and cystic degeneration of cervical lymph node metastasis. Posterior echo attenuation detected by ultrasound was associated with fibrous structures in PTMC nodules, while cystic degeneration and papillary changes of cervical lymph node metastasis in PTMC showed liquefactive necrosis, degenerative changes and enlarged follicular of nodular structures.

In this study, synergistic degradation of antibiotic norfloxacin (NOR) was obtained in a novel sonochemical ultrasound/zero-valent iron/tetraphosphate system (US/ZVI/TPP). Compared to three common organic ligands (EDTA, EDDS, and DTPA), TPP could perform more excellently in activation of O

Objective The aim of the study was to detect the valuable ultrasonographic features in diagnosing prostate cancer.

A method of reversed phase high performance liquid chromatography (RP-HPLC) coupled with a diode array detector (DAD) was developed for the simultaneous determination of 10 common flavonoids in propolis-rich functional foods. Flavonoids in a sample were extracted with methanol in an ultrasonic bath for 15 min and then chromatographically separated on a C 18 column. The binary mobile phase, composed of water with 1% tetrahydrofuran (pH = 2.5) and acetonitrile, was used for gradient elution. The proposed method revealed a good linearity between the peak area of each analyte and its concentration. The intra- and inter-day relative standard deviations (RSDs) were less than 1.90% and 4.91%, respectively. Recoveries were within the range of 84.2–118.7%. LODs and LOQs were 0.043–0.232 μg mL −1 ( S / N = 3) and 0.007–0.039 mg g −1 ( S / N = 10), respectively. The proposed method provided a simple and rapid routine analysis of common flavonoids in propolis-rich functional foods which are popular on the market nowadays.

In order to study the relationship between spinal cord injury and the change of nerve growth factor (NGF), an analytical method for NGF by capillary electrophoresis-based immunoassay (CEIA) with laser-induced fluorescence (LIF) was developed. Having been dissolved in phosphate buffer solution and concentrated with vacuum freeze-drying, NGF in spinal cord of rat was allowed to react with NGF monoclonal antibody labeled with fluorescence isothiocyanate (FITC). Then the immuno-complex, FITC-labeled anti-NGF and FITC were separated and determined by LIF-CEIA using Kiton red as the internal standard. The linear range of the method was 2–30 ng mL−1 and the limit of detection was 0.35 ng mL−1. The relative standard derivations for relative migration time and relative fluorescence intensity ratio were 7.98% and 6.52%, respectively. The contents of NGF from spinal cord of rat were determined by both the proposed method and Western blotting. The results with the two methods agreed well. The spiked recoveries of the samples were 88.5–116.3%. The proposed method was rapid, precise and inexpensive.

A generalized model for determining minimum-cost preventive maintenance schedules of a maintained reliability system is presented. Through balancing the cost of system failure during operation against the cost of planned maintenance, an optimal policy is established which minimizes the expected cost rate. A simple equation to determine the optimal period between maintenances for a system with the known failure distribution is acquired, and the calculation for the system with Gamma failure distribution is given.

Objective The aim of the study was to discuss the X-ray and CT manifestations and characteristics of pulmonary inflammatory pseudotumors.