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The cathode flow field design of a proton exchange membrane (PEM) fuel cell is essential to fuel cell performance, which directly affects the uniformity of reactant distribution and the ability to remove water. In this paper, the single serpentine flow field design on the cathode side is optimized to reach a high performance by controlling the rib groove rate (the ratio of the number of grooved ribs to the number of total ribs). The rib groove starts from the inlet side and then evenly distributes over the ribs. Four rib groove rates are selected in this study, namely, 0, 1/3, 2/3, and 1. A three-dimensional PEM fuel cell model is used to analyze the output performance of the fuel cell. The results indicate that the rib groove design has a significant effect on the distribution of oxygen at the cathode side, the density of the membrane current, the concentration of water vapor under the rib, and the fuel cell output performance. The output performance of the fuel cell improves with the increased rib groove rate. However, when the rib groove rate is greater than 2/3, its impact on the overall performance of the fuel cell begins to slow down. The PEM fuel cells exhibit the best output performance when the rib groove rate is 1.

Proton exchange membrane (PEM) fuel cell is an auspicious energy device for the future with high energy efficiency and zero emissions. PEM fuel cell performance can be improved by optimising the flow field using numerical models based on Brinkman-Darcy's law. However, errors made by applying Brinkman-Darcy's law cannot be avoided; errors should be carefully investigated for different flow fields. In this paper, a single-phase PEM fuel cell model based on Brinkman-Darcy's law was developed, considering the effects of flow field on both local electrochemical active area (ECA) and effective permeability. The results showed that the model well predicted the performance of the flow field with a high resolution land width, such as 1 mm, but it over-estimated the performance under the low voltage region when the land width was 2 mm or larger, since the high mass transfer loss was under-estimated by the model.

We have developed a method for the determination of trace levels of the rare earth elements La, Eu, and Yb in biological and environmental samples. It is based on solidified floating organic drop microextraction using 1-(2-pyridylazo)-2-naphthol (PAN) as a chelator, followed by electrothermal vaporization (ETV) and quantification by inductively coupled plasma mass spectrometry. PAN also acts as a modifier in ETV. The effects of pH, amount of PAN, extraction time, stirring rate, volume of sample solution, and temperature program were examined. Under optimized conditions, the detection limits are 2.1, 0.65 and 0.91 pg mL−1 for the elements La, Eu and Yb, respectively. The relative standard deviations are

In this work, a novel method was developed for the determination of trace rare earth elements in biological and environmental samples by inductively coupled plasma mass spectrometry (ICP-MS) after on-line preconcentration/separation with a titanium dioxide nanotube packed microcolumn. The adsorption behaviors of the analytes on titanium dioxide nanotubes were studied systematically. The effects of the experimental parameters, including pH, sample solution flow rate and volume, eluent concentration and volume and interfering ions, on the recoveries of the analytes were examined in detail. Under the optimum conditions, the detection limits of this method ranged from 0.19 pg mL− 1 (Lu) to 1.2 pg mL− 1 (La) with an enrichment factor of 100, and the relative standard deviations (RSDs) for the determination of REEs were less than 5.0% (n = 9, c = 1.0 ng mL− 1). The linear range of calibration curve spanned three orders of magnitude. This method was validated using a certified reference material of tea leaves, and successfully applied for the determination of trace light (La and Ce), medium (Eu and Gd) and heavy (Lu and Yb) rare earth elements in real samples with recoveries of 95.5–103%.

The study of the interaction between drugs and DNA is an important way to understand the role of drug molecules. A novel online analytical method for this purpose combining high-performance liquid chromatography-diode array detector-electrospray ionization-ion-trap time-of-flight mass spectrometry (HPLC-DAD-ESI-IT-TOF-MS(n)) and DNA-ethidium bromide detection with a fluorescence detector (DNA-EB-FLD) was firstly developed, which could rapidly identify the chemical constituents and obtain the profile related to DNA binding activity. This method has been applied for a precise or probable identification of the chemical constituents by ultraviolet (UV) absorption and MS(n) data analysis, while the DNA binding profile has been characterized by directly measuring the fluorescence intensity of compound-DNA-EB. Using this method, Trollius chinensis Bunge was studied and 18 constituents were identified by MS(n) data; six of them (4'-methoxy-2″-O-(2‴-methylbutyryl)vitexin,2″-O-(3‴-methoxycaffeoyl)vitexin) and 4'-methoxy-2″-O-(2‴-methylbutyryl)orientin,acacetin-7-O-rutinoside,quercetin-3-O-xylosylglucoside,quercetin-3-O-arabinosylglucoside) were identified for the first time in T. chinensis Bunge, and 16 constituents accounted for its activity of binding to DNA. The established (HPLC-DAD-ESI-IT-TOF-MS(n) DNA-EB-FLD) system has proved to offer a useful strategy for correlating the chemical profile with the binding to DNA activities of the components without their isolation and purification, and may be used for multicomponent analysis of active substances in other herbs.

This study was designed to investigate the effects of honokiol, a neuroprotective agent, on cerebral edema in cerebral ischemia reperfusion (IR) mice and its mechanism of anti-inflammation. Honokiol (0.7–70 μg/kg) significantly reduced brain water contents and decreased the exudation of Evans blue dye from brain capillaries in cerebral IR mice. Honokiol (0.1–10 μM) significantly reduced the p65 subunit level of NF-κB in the nucleus of primary culture-microglia. It (0.01–10 μM) evidently reduced nitric oxide (NO) level in the microglia culture medium and in the microglia and astrocytes coculture medium. Honokiol (0.01–10 μM) significantly decreased the level of TNF-α in the microglia medium or coculture cell medium. Honokiol (10 μM) decreased the level of Regulated upon Activation Normal T-cell Expressed and Secreted (RANTES/CCL5) protein in medium of microglia or astrocytes. In conclusion, Honokiol has a potent anti-inflammatory effect in cerebral ischemia-reperfusion mice and this effect might be attributed to its inhibition ability on the NF-κB activation, consequently blocking the production of inflammatory factors including: NO, tumor necrosis factor-α (TNF-α) and RANTES/CCL5 in glial cells. These results provide evidence for the anti-inflammatory effect of honokiol for the potential treatment of ischemic stroke.

The cyclic nucleotide phosphodiesterase (PDE) plays an important role in regulating the levels of second messenger molecules cAMP and cGMP. Various PDE inhibitors have been successfully developed into drugs for targeted diseases. In addition, PDE inhibitors can also be found in different foods and natural medicines. In this study, ultrafiltration liquid chromatography–diode-array detector–electrospray ionization–ion-trap–time-of-flight–mass spectrometry (ultrafiltration LC–DAD–ESI–IT–TOF–MS) was applied to screen PDE inhibitors from the roots of Ilex pubescens Hook. et Arn. As a result, 11 major compounds were identified in I. pubescens roots, with nine compounds as potential PDE inhibitors, among which five were further confirmed to be active against PDEI and PDE5A dose-dependently in vitro, with ilexsaponin A1 and ilexsaponin B2 being the strongest. HPLC quantification of these bioactive compounds suggested that they are major components in the plant. The results demonstrate that ultrafiltration LC–DAD–ESI–IT–TOF–MS is an efficient method for rapid screening of PDE inhibitors from natural medicines.

In order to study the diffusion layer porosity exchange membrane fuel cell properties of protons, in this thesis, direct-coupled multi-physics analysis software COMSOL Multiphysics 3D model four-stream channel serpentine flow field proton exchange membrane fuel (PEMFC), the porosity is considered separately the impact on cell performance 0.3,0.4,0.5,0.6. In the cell temperature is kept constant 353K to give the effect of porosity on the battery performance, temperature and pressure. The simulation results were analyzed and compared results: Cell temperature increases the porosity increases, and the more severe the greater the porosity of the reaction cell, cell pressure at the center of the flow channel is smaller, the pressure also will be reduced, so the greater the porosity, the better the battery performance. But the actual application at the same time increasing the porosity, thickness should be appropriately increased. The simulation results to improve fuel cell performance have some certain significance.

Transferrin (Tf) is an important protein responsible for circulating and transporting iron into cytoplasm. Tf can be taken into cells through endocytosis mediated by Tf receptor, which usually overexpresses in cancer cells. The Tf-Tf receptor pathway opens a possible avenue for novel targeted cancer therapy by utilizing Tf-binding active compounds. Among which, anti-cancer active caffeoylquinic acids (CQAs) were recently found to be promising Tf-binders by our group. For better understanding the anti-cancer activities of CQAs, it is important to unveil the binding mechanisms between CQAs and Tf. In this study, the fluorescence quenching, surface plasmon resonance (SPR), circular dichroism (CD) and molecular docking were used to investigate the interactions between CQA and Tf. The results showed that the calculated apparent association constants of interactions between 1-, 3-, 4- and 5-CQA and Tf at 298K were 7.97×105M-1, 4.36×107M-1, 6.58×105M-1 and 4.42×106M-1, respectively. The thermodynamic parameters indicated that the interaction between 1-, 3-, 5-CQA and Tf is due to H-bonding, and electrostatic interactions were likely involved in the binding of 4-CQA and Tf. The CD results indicated that bindings of 1-CQA, 4-CQA and 5-CQA with Tf resulted in more stretched β-turn and random coil translated from β-sheet. In contrast, 3-CQA led to more stable a-helix conformation. Molecular docking studies of CQAs with Tf further displayed that CQAs were able to interact with residues near Fe3+ binding site. The spectroscopic studies revealed the action mechanisms, thermodynamics and interacting forces between CQAs and Tf, and thus are helpful for future design and discovery of Tf-binders for targeted cancer therapy applying Tf-Tf receptor pathway.

This article aims to conduct toxicity test research on honokiol microemulsion(HM) to provide reference frame for the safe dose design as well as the toxic and adverse reaction monitoring in clinic. High performance liquid chromatography (HPLC) method was adopted to determine the concentration, stability and uniformity of HM and the results indicated that the test sample was conformed to the toxicity test requirements. In the acute toxicity test, six intravenous drip dosages, namely, 100.0, 66.7, 44.4, 19.8, 8.8, and 3.9 mg/kg were set, with one beagle dog in each dosage, respectively. In addition, the results also demonstrated that the approximate lethal dose range of HM was 66.7–100.0 mg/kg. In the subchronic toxicity test, beagle dogs were intravenously dripped with HM at doses of 1.25, 0.25 and 0.05 mg/kg for 30 days. During the test period, signs of gross toxicity, behavioral changes, body weight, rectal temperature, food consumption, ophthalmoscopy, electrocardiography, urinalysis, blood biochemistry, coagulation, hematology, organ weights and histopathology were examined. Under the present study conditions, the no-observed-adverse-effect level for HM was estimated to be 0.25 mg/kg. According to the results of bacterial reverse mutation, chromosomal aberration and micronucleus assays, HM exhibited no notable genotoxicity both in vivo and in vitro.

Fufang Banbianlian Injection (FBI) has been widely used as an anti-inflammatory and anti-tumor prescription. To understand the relationships between its bioactive ingredients and pharmacological efficacies, our previous study has been successfully identified some DNA-binding compounds in FBI using an established on-line screening system, in which 4',6-diamidino-2-phenylindole (DAPI) was developed as a probe. However, DAPI can be only used to screen ATT-specific DNA minor groove binders, leaving the potential active intercalators unknown in FBI. As a continuation of our studies on FBI, here we present a sensitive analytical method for rapid identification and evaluation of DNA-intercalators using propidium iodide (PI) as a fluorescent probe. We have firstly established the technique of high-performance liquid chromatography-diode-array detector-multistage mass spectrometry-deoxyribonucleic acid-propidium iodide-fluorescence detector (HPLC-DAD-MS(n)-DNA-PI-FLD) system. As a result, 38 of 58 previously identified compounds in FBI were DNA-intercalation active. Interestingly, all previously reported DNA-binders also showed intercalative activities, suggesting they are dual-mode DNA-binders. Quantitative study showed that flavonoid glycosides and chlorogenic acids were the main active compounds in FBI, and displayed similar DNA-binding ability using either DAPI or PI. In addition, 13 active compounds were used to establish the structure-activity relationships. In this study, PI was developed into an on-line method for identifying DNA-intercalators for the first time, and thus it will be a useful high-throughput screening technique for other related samples.

A simple, sensible, and reliable HPLC–DAD method was first developed for fingerprint analysis of Alismatis Rhizoma, and then applied to analyze 85 samples from three main cultivated areas. In all, 40 common fingerprint peaks were designated, and six of which were definitely identified. Then, the combinatory analysis using similarity evaluation, principal component analysis, and orthogonal partial least square discriminant analysis revealed clear chemical consistency between samples from Fujian and Jiangxi provinces and substantial differences between those from Fujian/Jiangxi and Sichuan provinces. Furthermore, six components were dug out as potential chemical markers for distinguishing Alismatis Rhizoma from different areas, among which five were qualified for quantitative analysis. In conclusion, the combination of chemical fingerprint, multiple components quantification, and pattern recognition analysis was rather powerful and useful in discriminating Alismatis Rhizoma from different regions, which was a benefit for quality control.

Radix Puerariae (RP) is a botanical supplement widely used as a nutraceutical in functional foods. The developed method by coupling HPLC-DAD-IT-TOF-MS n with post-column derivatization (PCD) has been used for separation and identification of 22 isoflavones in RP. In addition, a total of 15 isoflavones were simultaneously determined in one single HPLC run with photodiode array detection (DAD), 8 of which were quantified in Radix Puerariae for the first time. Content determination results were used to comprehensively evaluate qualities of Radix Puerariae samples from different natural habitats in China. A YMC™ C 18 column (150 mm × 4.6 mm i.d.; 5 μm particle size) and gradient elution (acetonitrile and water with 0.02% (v/v) of formic acid) were used during the analysis. All calibration curves showed good linearity (r > 0.9996) within the test ranges. The intra-day and inter-day stability for 15 analytes were less than 1.32% and 1.87%, respectively. The recoveries were between 95.1% and 103.5%. The established method was simple, feasible and practical, and could be applied to routine analysis of Radix Puerariae and its preparation. The research set a good example for the comprehensive quality control of Radix Puerariae .

A new on-line method for simultaneous identification and monitoring of antioxidants in Fructus aurantii was established by coupling high performance liquid chromatography-diode array detector-electrospray ionisation-ion trap-time of flight-mass spectrometry with post-column derivatisation and luminol-potassium ferricyanide chemiluminescence (HPLC-DAD-ESI-IT-TOF-MS-PCD-LPFCL). While the HPLC fingerprint, structural identification and radical scavenging profile were rapidly obtained by an on-line assay using ultraviolet (UV) absorption, MS and LPFCL, details of the precise substitution patterns of various structures were achieved through UV absorption using PCD addition of shift reagents. Twenty-five flavonoids were identified by either their PCD and MS data or comparison with reference substances. Data collected both from chromatograms and activity profiles of 12 samples revealed significant differences among samples from different habitats. The results showed that this method was rapid and precise, and therefore would be an effective and sensitive method for biocompounds analysis and quality evaluation for complex food and medicinal samples.

Introduction Flos Chrysanthemi (Jiju) is a traditional Chinese medicine (TCM) that is known to have anti-oxidant activity; in this study, on-line HPLC–DAD–ESI/MSn and HPLC–DAD–DPPH methods have been developed for rapidly screening and identifying free-radical scavengers in Jiju extract. Objective To develop an efficient method for the simultaneous identification and detection of the anti-oxidant components in Flos Chrysanthemi (Jiju). Methodology A concentrated methanol extract of Flos Chrysanthemi from Jiaxiang County (Jiju) was first separated into phases soluble in water, petroleum ether and n-butanol. The off-line 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging method was then used to evaluate the anti-oxidant activity of each phase in vitro. The results showed that the n-butanol extract had the highest anti-oxidant activity, and its anti-oxidant compounds were analysed by HPLC–DAD–ESI/MSn and HPLC coupled with a post-column derivatisation (PCD) system supplied with DPPH, aluminium chloride or sodium acetate solutions. Results A total of 17 compounds were separated and identified, three of which were identified in Jiju for the first time, and seven active compounds serve as the chemical basis of the anti-oxidant efficacy of Jiju. Conclusion The methods described here allow rapid separation and convenient identification of the multiple constituents in Jiju, and may be applied to other complex natural matrices. Copyright © 2012 John Wiley & Sons, Ltd.

Flos Chrysanthemi (Gongju, GJ) is used to prepare a herbal tea that is commonly consumed as a health beverage in Asia and is believed to contain abundant beneficial antioxidants. To rapidly identify the chemical constituents and to obtain the profile related to antioxidant activity, an online analytical method combining high-performance liquid chromatography-diode-array detector-electrospray ionization-ion-trap time-of-flight mass spectrometry (HPLC-DAD-ESI-IT-TOF-MS(n)) and postcolumn derivatization (PCD) has been applied for a precise and thorough identification of the chemical constituents. Meanwhile, the antioxidant profile has also been characterized by directly measuring the scavenging activity of each compound for the free radical produced by DPPH. As a result, 13 compounds have been identified in GJ, 7 of which account for its antioxidant activity. The established LC-MS(n)-PCD system has proved to offer a useful strategy for correlating the chemical profile with the bioactivities of the components without their isolation and purification, and may be used for multicomponent analysis of active substances in other foods and herbs.

Based on thermal stability and volatility of 1-phenyl-3-methyl-4-benzoyl-5-pyrazone (PMBP) chelate, a novel method was described for the determination of Cr(III) and Cr(VI) by low-temperature electrothermal vaporization (LETV) combined with inductively coupled plasma mass spectrometry (ICP-MS). It was found that Cr(III) could be rapidly formed in a graphite furnace, and quantitatively vaporized into ICP at a relatively low temperature of 1000 °C with the use of PMBP as a chemical modifier, while Cr(VI) was retained in the graphite tube. Thus, the separation of Cr(III) and Cr(VI) could be realized. The main factors affecting the formation and vaporization of Cr(III)-PMBP chelate were investigated in detail. Under the optimized conditions, the detection limit of Cr(III) for this method was 0.031 ng mL −1 and the relative standard deviation (RSD) for 1.0 ng mL −1 Cr(III) was 5.3% ( n = 9, v = 10 μL). The linear range of calibration curve spanned three orders of magnitude. The proposed method was applied to the determination of Cr(III) and Cr(VI) in water samples with satisfactory results.

Experimental purpose is to test gravity influence on water discharged in PEM fuel cell cathode. Through changing the way of placement of the cathode and anode, it takes adjusting the electronic load to test the output of voltage and current. Corresponding to the position of the cathode-upward and the anode-upward, different humidification condition, draws the polarization curve using the voltage and current density. According to the placing position of the cathode and anode, cell temperature, humidification temperature of the cathode and anode gas, 4 groups of experimental results are obtained. The experimental conclusion is: when a PEM fuel cell is placed anode-upward, gravity is advantageous to discharge the liquid water in PEM fuel cell cathode. On the contrary, gravity is disadvantageous to discharge the liquid water.

Microcolumn packed single-walled carbon nanotubes (SWCNTs) were used as solid phase extraction adsorbent for chromium speciation coupled to inductively coupled plasma mass spectrometry for detection. The effects of the experimental parameters, including pH of the solution, sample flow rate, volume and concentration of eluent, sample volume and interfering ions, on separation and determination of Cr(III) and Cr(VI) were investigated in detail. It was found that Cr(III) was selectively sorbed on the microcolumn packed with SWCNTs in the pH range from 2.0 to 4.0, while Cr(VI) remained in solution. The retained Cr(III) was subsequently eluted with 2.0 mL of 1.2 mol L−1 nitric acid. Under the optimum conditions, the detection limits based on 3σ criterion were 0.01 ng mL−1 and 0.024 ng mL−1 for Cr(III) and Cr(VI), respectively. The relative standard deviations were less than 5.0% (n = 9, c = 1.0 ng mL−1). The method was successfully applied to the speciation of chromium in real samples including natural and waste water. The recoveries of spiked samples were higher than 92.5%.

The ultramafic body sampled in the Chinese Continental Scientific Drilling (CCSD) Hole PP3 is located in the eastern part of the Dabie–Sulu UHP metamorphic belt near Donghai County. It is about 480 m thick, and consists chiefly of garnet peridotite, dunite and serpentinite. The principal minerals include olivine, chromium spinel, diopside, enstatite, garnet with minor secondary augite, phlogopite and amphibole. Both the olivine and orthopyroxene are highly magnesian, and the garnet is pyropic with 5.4–6.4% CaO and 0.3–3.3% Cr 2 O 3 . Two generations of clinopyroxene are present; an early diopside followed by augite. Chromium spinels are highly variable with Cr#s (100Cr / (Cr + Al)) between 51 and 89, and their compositions reflect different processes of formation, namely partial melting and eclogite, amphibole and greenschist facies metamorphism. The Mg#s (100 Mg / (Mg + Fe 2+ ))of the spinels correlate positively with the Cr#s but negatively with oxygen fugacity. Based on the spinel compositions the ultramafic rocks originated in the shallow mantle, then subducted to depths of more than 100 km and finally exhumed to the surface. They underwent partial melting at shallow depths, mostly in the spinel facies, and were later transformed into garnet peridotites during deep subduction. All of the rocks were weakly metasomatized during exhumation and were subjected to retrograde metamorphism.

The main hole (MH), and pre-pilot holes PP1, and PP3 of the Chinese Continental Scientific Drilling Project (CCSD) penetrated three different garnet peridotite bodies in the Sulu ultrahigh pressure (UHP) metamorphic belt, which are 80 m, 120 m, and 430 m thick, respectively. The bodies occur as tectonic blocks hosted in eclogite (MH peridotite) and gneisses (PP1 and PP3 peridotites). The peridotites in the MH are garnet wehrlites, whose protoliths were ultramafic cumulates based on olivine compositions (Fo 79–89 ) and other geochemical features. Zoned garnet and omphacite (with 4–5 wt.% Na 2 O) are typical metamorphic minerals in these rocks, and, along with P – T estimates based on mineral pairs, suggest that the rocks have undergone UHP metamorphism. SHRIMP U–Pb isotope dating of zircon from the garnet wehrlite yielded a Paleozoic protolith age (ca. 346–461 Ma), and a Mesozoic UHP metamorphic age (ca. 220–240 Ma). The peridotites in PP1 consist of interlayered garnet (Grt)-bearing and garnet-free (GF) peridotite. Both types of peridotite have depleted mantle compositions (Mg# = 90–92) and they display transitional geochemical features. The intercalated layers probably reflect variations in partial melting rather than pressure variations during metamorphism, and the garnets may have been formed by exsolution from orthopyroxene during exhumation. These peridotites were probably part of the mantle wedge above the subduction zone that produced the UHP metamorphism and thus belonged to the North China Block before its tectonic emplacement. The exhumation of the subducted Yangtze Block brought these mantle fragments to shallow crustal levels. The ultramafic rocks in PP3 are dominantly dunite with minor garnet dunite. Their high Mg# (92–93) and relatively uniform chemical compositions indicate that they are part of a depleted mantle sequence. The presence of garnet replacing spinel and enclosing pre-metamorphic minerals such as olivine, clinopyroxene and spinel suggests that these rocks have undergone progressive metamorphism. SHRIMP U–Pb isotope dating of zircon from these rocks yielded two age groups: 726 ± 56 Ma for relic magmatic zircon grains and 240 ± 2.7 Ma for the newly formed metamorphic zircon. The older group is similar in age to granitic intrusions within the Dabie–Sulu belt, suggesting that the PP3 garnet peridotite may record the early emplacement of the peridotite into the crust. The younger dates coincide with the age of UHP metamorphism during continent–continent collision between the Yangtze and North China Blocks, suggesting that these peridotites were subducted to depths equivalent to the coesite facies and later exhumed. Thus, the garnet peridotites in the CCSD cores include both ultramafic rocks that existed originally in the subducted plate and rocks from the mantle wedge above the subducted plate, i.e., part of the North China Block.

In this paper, carbon nanofibers (CNFs) as a novel solid phase extraction sorbent were developed for speciation preconcentration and separation of inorganic arsenic species As(III) and As(V) prior to determination by inductively coupled plasma mass spectrometry (ICP-MS). It was found that during all the steps of the separation, As(III) was selectively sorbed on the microcolumn packed with CNFs within a pH range of 1.0-3.0 in the presence of ammonium pyrroinedithiocarbamate (APDC), while As(V) was passed through the microcolumn without the retention. Various experimental parameters affecting the separation and determination of As(III) and As(V) have been investigated in detail. Under the optimized conditions, the detection limits of this method for As(III) were 0.0045 ng mL(-1) with an enrichment factor of 33 and 0.24 ng mL(-1) for As(V), and the relative standard deviations for As(III) and As(V) were 2.6% and 1.9% (n=9, c=1.0 ng mL(-1)), respectively. In order to verify the accuracy of the method, a certified reference of water sample was analyzed, and the results obtained were in good agreement with the certified values. The proposed method was applied for the analysis of inorganic arsenic species in groundwater and lake water with the recovery of 92-106%.

Systematic investigations were carried out into the sorption of rare earth elements (REEs) on carbon nonofibers (CNFs) by inductively coupled plasma mass spectrometry (ICP‐MS). The experimental parameters for preconcentration of REEs, such as pH, sample flow rate and volume, eluent concentration, and interfering ions on preconcentration of REEs have been examined in detail. The studied metal ions can be adsorbed quantitatively on CNFs in a pH range from 2.0 to 5.0, and then eluted completely with 0.5 mol l−1 HNO3. Based on the above facts, a novel method using a microcolumn packed with carbon nanofibers as an adsorption material was developed for the separation and preconcentration of REEs prior to their determination by ICP‐MS. The proposed method has been successfully applied to the determination of light (La), medium (Eu and Gd) and heavy (Yb) rare earth elements in real sample with the recovery more than 90%. In order to validate this method, two certified reference materials of tea leaves (G...

Cyclovirobuxine D is an active compound extracted from Buxus microphylla, which has been used for treating acute myocardial ischemia in China. The present study was to investigate its mechanism on myocardial ischemia. Cyclovirobuxine D significantly increased cardiomyocytes viability injured by oxidation or hypoxia. It significantly reduced the infarct size induced by ligating the coronary artery in rats, and the effect was almost abolished by glibenclamide, a blocker of ATP sensitive potassium channel, but it was not influenced by cyclooxygenase-2 inhibitor celecoxib or estrogen receptor antagonist tamoxifen. In addition, cyclovirobuxine D significantly protected rat aorta endothelial cells against hypoxia and enhanced nitric oxide (NO) release from endothelial cells, which was inhibited by nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME). Furthermore, cyclovirobuxine D significantly decreased the weight of venous thrombus in rats. In conclusion, the action mechanism of cyclovirobuxine D on myocardial ischemia may be related with its cytoprotection, K(ATP) channel opening, NO generation stimulating and venous thrombosis inhibiting.

In this work, a new method was developed for the determination of trace rare earth elements (REEs) in biological samples by inductively coupled plasma mass spectrometry (ICP-MS) after preconcentration on a microcolumn packed with modified carbon nanofibers (CNFs). CNFs oxidized with nitric acid have been proved to possess an exceptional adsorption capability for REEs due to their surface functionalization. The effects of the experimental parameters, including pH, sample flow rate and volume, elution solution and interfering ions, on the recoveries of the analytes have been investigated systematically. A 100-fold enrichment factor was obtained. The adsorption capacity of CNFs was found to be 18.1, 19.3, 23.6, 17.6, 22.3 and 19.5 mg/g for La, Ce, Sm, Eu, Dy and Y, respectively. Under the optimum conditions, the detection limits of this method ranged from 0.2 pg/mL (Dy) to 1.2 pg/mL (Ce) with an enrichment factor of 15-fold, and the relative standard deviations (RSDs) for the determination of REEs at the 1.0 ng/mL level were less than 4% (n = 9). This method was applied to the analysis of trace REEs in a real sample of human hair with recoveries of 95-115%. In order to validate the proposed method, a certified reference material of human hair (GBW 07601) was analyzed with satisfactory results.

Honokiol is a bioactive compound extracted from the Chinese medicinal herb Magnolia officinalis. We recently demonstrated that honokiol inhibited arterial thrombosis through stimulation of prostacyclin (PGI2) generation and endothelial cell protection. The current study is designed to investigate its mechanism of stimulation of PGI2 generation and cell protection. 6-keto-PGF1alpha, the stable metabolite of PGI2, in the media of rat aortic endothelial cells was measured with radioimmunoassay kits. Indomethacin, an inhibitor of cyclooxygenase (COX) and tranylcypromine, a prostacyclin synthease inhibitor were used to ascertain the target enzyme affected by honokiol. Prostacyclin synthease protein levels in endothelial cells were determined by Western blot analysis using an anti-PGI2 synthease rabbit polyclonal antibody. Flow cytometry was used to quantify the apoptotic cells and spectrophotometry was used to test the caspase-3 activity. Honokiol (0.376-37.6 microM) increased the level of 6-keto-PGF1alpha in the media of normal endothelial cells. It counteracted the inhibitory effect of tranylcypromine on the PGI2 generation, but did not influence the effect of indomethacin; evidently, honokiol up-regulated the expression of prostacyclin synthease in the endothelial cells. These effects showed perfect concentration-dependent behavior. In addition, at lower concentration (0.376-3.76 microM), honokiol significantly decreased the percentage of apoptotic endothelial cells induced by oxidized low-density lipoprotein (ox-LDL) and significantly lowered the activity of caspase-3 stimulated by ox-LDL. A high dose of honokiol (37.6 microM), however, failed to influence either of them. In conclusion, honokiol augments PGI2 generation in normal endothelial cells; its effect on PGI2 generation attributes to up-regulation of prostacyclin synthease expression; its cell protection may be correlated with its inhibition on apoptosis of endothelial cells. These findings have partly revealed the molecular mechanism of honokiol on inhibiting arterial thrombosis.

A mass spectrometry method that combines electrospray with an ion trap time-of-flight mass analyzer has been used to characterize puerarin (7,4′-dihydroxyisoflavone-8-C-β-D-glucoside). MSn spectra (n ≤ 6) were obtained in positive and negative ion mode. The combination of accurate mass measurement in MS2 spectra and sequential MSn experiments enabled fragmentation pathways to be elucidated in detail. A novel structure for [M+H−150]+ has been found. Copyright © 2007 John Wiley & Sons, Ltd.

Fufang Banbianlian Injection (FBI) is a well-known traditional Chinese medicine formula composed of three herbal medicines. However, the systematic investigation on its chemical components has not been reported yet. In this study, a high-performance liquid chromatography combined with diode-array detector, and coupled to an electrospray ionization with ion-trap time-of-flight mass spectrometry (HPLC-DAD-ESI-IT-TOF-MS) method, was established for the identification of chemical profile in FBI. Sixty-six major constituents (14 phenolic acids, 14 iridoids, 20 flavonoids, 2 benzylideneacetone compounds, 3 phenylethanoid glycosides, 1 coumarin, 1 lignan, 3 nucleosides, 1 amino acids, 1 monosaccharides, 2 oligosaccharides, 3 alduronic acids and citric acid) were identified or tentatively characterized by comparing their retention times and MS spectra with those of standards or literature data. Finally, all constituents were further assigned in the individual herbs (InHs), although some of them were from multiple InHs. As a result, 11 compounds were from Lobelia chinensis Lour, 33 compounds were from Scutellaria barbata D. Don and 38 compounds were from Hedyotis diffusa Willd. In conclusion, the developed HPLC-DAD-ESI-IT-TOF-MS method is a rapid and efficient technique for analysis of FBI sample, and could be a valuable method for the further study on the quality control of the FBI.

The aim of this study was to evaluate the embryo-fetal development toxicity of honokiol microemulsion. The drug was intravenously injected to pregnant SD rats at dose levels of 0, 200, 600 and 2000 μg/kg/day from day 6-15 of gestation. All the pregnant animals were observed for body weights and any abnormal changes and subjected to caesarean-section on gestation day (GD) 20; all fetuses obtained from caesarean-section were assessed by external inspection, visceral and skeletal examinations. No treatment-related external alterations as well as visceral and skeletal malformations were observed in honokiol microemulsion groups. There was no significant difference in the body weight gain of the pregnant rats, average number of corpora lutea, and the gravid uterus weight in the honokiol microemulsion groups compared with the vehicle control group. However, at a dose level of 2000 μg/kg/day, there was embryo-fetal developmental toxicity observed, including a decrease in the body length and tail length of fetuses. In conclusion, the no-observed-adverse-effect level (NOAEL) of honokiol microemulsion is 600 μg/kg/day, 75 times above the therapeutic dosage and it has embryo-fetal toxicity at a dose level of 2000 μg/kg/day, which is approximately 250 times above the therapeutic dosage.

PurposeExternal knowledge is generally believed to be of prime importance to small to medium‐sized enterprises (SMEs). However, a review of the literature shows that no empirical research has looked at knowledge management issues at the inter‐organizational level in SMEs. This paper seeks to report on an empirical investigation with UK SMEs in the service sector to identify their needs and practices regarding inter‐organizational knowledge transfer, and thus provide empirical evidence to support the above belief.Design/methodology/approachA two‐tier methodology (i.e. using both questionnaire survey and interview approaches) is deployed to address the main research objectives. A questionnaire survey of SMEs is carried out to investigate their current inter‐organizational knowledge transfer situation and managers' perception on various relevant issues. Then 12 face‐to‐face interviews with SME managers are conducted to further validate key findings drawn from the questionnaire survey.FindingsThe empirical evidence collected from the survey and interviews confirms the general belief that external knowledge is of prime importance for SMEs, and demonstrates that SMEs have very strong needs for external knowledge and inter‐organizational knowledge transfer.Research limitations/implicationsThe findings provide very strong underpinning for further theoretical research on inter‐organizational knowledge transfer in SMEs. However, this study has certain limitations: its results may not be applicable to other industrial sectors or the same sector in other countries; or to micro or large companies; nor does it involve cross‐cultural issues.Originality/valueBy adopting a two‐tier research methodology, this study provides more reliable understanding and knowledge on SMEs' inter‐organizational knowledge transfer needs and practices, and fills the gap that exists in the empirical investigations on the subject.

A novel method for the determination of trace rare earth impurities in ZrO 2 powder has been developed based on electrothermal vaporization inductively coupled plasma atomic emission spectrometry. A polytetrafluoroethylene slurry was used as a fluorinating reagent to convert both the matrix (Zr) and the analytes (rare earth elements) into fluorides with different volatilities at a high temperature in a graphite furnace. The more volatile ZrF 4 was removed in-situ by selective vaporization prior to the determination of the analytes, removing matrix spectral interferences. Under optimum operating conditions, the absolute detection limits of the analytes varied from 0.04 ng (Yb) to 0.50 ng (Pr) with relative standard deviations less than 5%. The recommended approach has been successfully applied to the determination of trace rare earth impurities (La, Pr, Eu, Gd, Ho and Yb) in ZrO 2 powder and the results were in good agreement with those obtained by pneumatic nebulization inductively coupled plasma atomic emission spectrometry after the separation of the matrix using a solvent extraction procedure.

A low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) method was developed for the determination of the refractory yttrium, using 1-(2-pyridylazo)-2-naphthol (PAN) as chemical modifier. The trace yttrium was vaporized as PAN complex into plasma from a graphite furnace at a comparatively low temperature of 1200 °C. The operation conditions were optimized, and the vaporization behavior of Y–PAN chelate and the main factors affecting the determination were investigated in detail. Under the optimized conditions, the detection limit of Y was 0.7 ng ml−1, and the relative standard deviation (R.S.D.) for 0.1 μg ml−1 Y was 4.5% (n=9, v=10 μl). The linear range of calibration curve covered three orders of magnitude. The recommended approach has been applied for analysis of three biological samples with satisfactory results. The accuracy of the method was demonstrated by analyzing two standard reference materials.

The purpose of this study was to investigate the acute and sub-chronic toxicity of honokiol microemulsion. In the acute toxicity tests, the mice were intravenously injected graded doses of honokiol microemulsion and were observed for toxic symptoms and mortality daily for 14 days. In the sub-chronic toxicity study, rats were injected honokiol microemulsion at doses of 100, 500, 2500 μg/kg body weight (BW) for 30 days. After 30 days treatment and 14 days recovery, the rats were sacrificed for hematological, biochemical and histological examination. In the acute toxicity tests, the estimated median lethal dosage (LD50) was 50.5mg/kg body weight in mice. In the sub-chronic toxicity tests, the non-toxic reaction dose was 500 μg/kg body weight. In each treatment group, degeneration or/and necrosis in vascular endothelial cells and structure change of vessel wall can be observed in the injection site (cauda vein) of a few animals while there were no changes in the vessels of other organs. The overall findings of this study indicate that the honokiol microemulsion is non-toxic up to 500 μg/kg body weight, and it has irritation to the vascular of the injection site which should be paid attention to in clinical medication.

Solidified floating organic drop microextraction was combined with electrothermal vapourisation inductively coupled plasma mass spectrometry for Se species in Se-rich tea leaves and tea infusion, including total, suspended, soluble, organic and inorganic Se as well as Se(IV) and Se(VI). Ammonium pyrrolidinedithiocarbamate was used as both chelating reagent and chemical modifier in this study. Se(IV) and Se(VI) were separated at pH range of 2.0-5.0. An enrichment factor of 500 was obtained for Se(IV) from this method. Under the optimum conditions, the detection limits for Se(IV) and Se(VI) were 0.19 and 0.26pgmL(-1), respectively. The relative standard deviations were less than 5.5% (c=0.1ngmL(-1), n=9). This method was applied for Se species, its content and distribution in Se-rich tea leaves and tea infusion with satisfactory results. The recoveries of spike experiments are in the range of 92.2-106%. A certified reference material of tea leaves was analyzed by this method, and the results were in agreement with certified values.

A low temperature electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) method for the determination of palladium, by using sample introduction of gaseous palladium oxinate, was developed. The thermally stable palladium oxinate was formed and vaporized at a temperature of 900 °C from the graphite furnace. The main factors affecting the vaporization behavior of the analyte were investigated in detail. The detection limit of palladium for this method was 50 pg, and the relative standard deviation (RSD) for 0.2 µg ml−1 palladium was 4.7% (n = 8). Compared with conventional ETV-ICP-AES, the analytical sensitivity of this method was improved by one order of magnitude. The proposed method was applied to the determination of trace palladium in geological samples with satisfactory results.

The Mazhuangshan area is located in the east of the Aqikekuduke Island Arc, where there are distributed intermediate-acid magmatic rocks emplaced during the Middle-Late Carboniferous. There are more than 20 orebodies in the area with an average gold grade 6.4 × 10−6 at present. The dominant metallic minerals are natural gold, auriferous silver, natural silver, pyrite and galena. Pyrite is the key gold carrier, high in Fe and low in S. Wall-rock alterations mainly include pyritization, silicification, and sericitization. Carbonation alteration was extensive at the late stage, often resulting in a high-grade orebody. Three mineralization stages may be distinguished.

The Mazhuangshan area lies in northeast to Aqikekuduke, where are distributed intermediate-acid rocks, which were formed in the Middle-Late Carboniferous epoch. The magmatic rocks are peraluminous and belong to calcareous series. All values of ACNK(1.03–2.12), ANK (1.67–2.93), SI(4.1–33), δ(0.71–4.82), La/ΣREE(0.09–0.26) ΣLREE/ΣHREE(1.76–11.01), (La/Sm)N(l.60–6.35), (Sm/Nd)N(0.33–0.58), (La/Yb)N(4.7–12.1), LaN/LuX(5.9–11.8), (Ce/Yb)N(3.14–6.64), δEu(0.38–1.06), RbN/SrN(42–120) and Sr* (0.02–0.2) demonstrate they vary with D_ I(45–90). S-B diagram also shows that the lithophile elements are abundant in acidic magmatic rocks. Moreover, it is concluded that the primitive magma originated from a subduction zone at the continental edge, and underwent fractional crystallization and contamination, then generated the magmatic rocks. The multi-cation index (R1: 3055–3993, R2: 286–438) shows that the primitive magma originated from the mantle. All these conclusions are beneficial for exploring gold deposits in the area.

Fractalkine is an endothelial cell-derived CX3C chemokine that is chemotactic mainly to mononuclear cells. Fractalkine was induced in rat aortic endothelial cells (RAEC) by interleu-kin-1β (IL-1β), tumor necrosis factor α (TNF-α), and lipopolysaccharide (LPS) transcriptionally and translationally. This induction correlated with increased NF-κB DNA binding activity as determined by gel mobility shift assay. Supershift assays revealed that the NF-κB subunits p50 and p65 were responsible for κB binding. Accordingly, we examined the role of NF-κB in fractalkine induction in RAEC through the use of an adenovirus-mediated mutant IκB as a specific inhibitor. Delivery of a dominant-negative form of IκBα in RAEC dramatically reduced the induction of fractalkine by these stimuli, suggesting a role for NF-κB activation in fractalkine induction. The inhibition of fractalkine expression by two potent NF-κB inhibitors, sulfasalazine and sanguinarine, further supported the central role of NF-κB in fractalkine transcription regulation and suggested a novel therapeutic target aimed at modulating leukocyte endothelial cell interaction. J. Leukoc. Biol. 67: 577–584; 2000.

Members of the Rel/NF-κB family of transcription factors play a central role in the regulation of inflammatory and immune responses (for recent reviews, please see (1, 3, 4, 25, 46, 54). In vertebrates, NF-κB consists of homo- or heterodimers of Rel (c-Rel), p65 (RelA), RelB, p50 (NFKB1), and p52 (NFKB2), all of which contain a conserved N-terminal Rel homology domain that contains the DNA-binding and dimerization domains and the nuclear localization signal. In most unstimulated cells, a large portion of NF-κB is retained in the cytoplasm as inactive complexes by a family of inhibitory proteins called IκB that bind to the Rel homology domain and mask the nuclear localization signal. There are at least five distinct IκB proteins, IκBα, IκBβ, IκBɛ, IκBγ, and bcl-3; both the p105 precursor of p50 and the p100 precursor of p52 possess domains that function as IκBs as well. Upon cell stimulation by a wide variety of stimuli, signal-responsive IκB kinases (IKK) α and β are activated and phosphorylate two serine residues in the IκB proteins (14, 19, 36, 42, 43, 61, 63, 64). For IκBα and IκBβ, the inducible phosphorylation sites are serines 32 and 36 and serines 19 and 23, respectively (9, 10, 18, 51). The phosphorylated IκBs are subsequently ubiquitinated and targeted for degradation by the 26S proteosome, releasing the NF-κB dimers to translocate to the nucleus to activate the transcription of genes containing the so-called κB-binding site (2, 26, 48). Among the NF-κB-inducible genes are IκB members, and the newly synthesized IκBs quickly interact with and inactivate NF-κB, leading to an autoregulation of the NF-κB system (11, 45, 50). Both IκBα and IκBβ function not only in the cytoplasm but also in the nucleus to inhibit NF-κB activity; however, only IκBα is required for postinduction repression of NF-κB (5, 52). RelB shares many common features of the NF-κB family, and is a strong transcriptional activator (7, 8, 21, 44). Unlike other NF-κB members, however, RelB cannot form homodimers and only associates efficiently with p50 and p52 (22). The RelB heterodimers have a much lower affinity for IκBα than other NF-κB complexes do and are less susceptible to inhibition by IκBα (22, 32). As a result, it is predicted that RelB will be located in the nucleus and represent the constitutive NF-κB activity. Indeed, RelB heterodimers represent the major constitutive NF-κB activity in lymphoid tissues and are expressed at high levels in the nuclei of interdigitating dendritic cells, suggesting an important role for RelB in the constitutive expression of κB-regulated genes in lymphoid tissues (13, 32, 33, 40, 56). The implicated in vivo function of RelB in lymphoid tissues is supported by studies of relb−/− mice (12, 17, 34, 57–60, 62). Mice deficient in RelB have a dramatic reduction in constitutive κB-binding activity and specific defects in lymphoid tissues, including the absence of mature lymphoid dendritic cells, myeloid hyperplasia, and splenomegaly (12, 57). relb−/− mice also have multifocal defects in immune responses and fail to mount inflammatory reactions against a number of pathogens (17, 60). Surprisingly, relb−/− mice spontaneously develop a persistent noninfectious multiorgan inflammatory syndrome (12, 34, 57). This apparent discrepancy suggests additional defects in nonlymphoid tissues in relb−/− mice. In this regard, we showed in our previous report that the multifocal inflammation is due to non-bone-marrow-derived cells, that lipopolysaccharide (LPS)-stimulated relb−/− fibroblasts overexpress chemokines and induce leukocyte recruitment into tissues, and that RelB, while being a transcriptional activator for κB-regulated genes in macrophages, acts as a transcription suppressor in fibroblasts (62). Our findings may provide hints about the role that fibroblasts might play in the initial leukocyte infiltration and how RelB might be involved in the regulation of this process (49, 62). Additional pathological changes, however, must be involved in the development of multiorgan inflammation in relb−/− mice. Cytokines which promote inflammatory effector functions, including tumor necrosis factor alpha (TNF-α), interleukin-1α (IL-1α), IL-1β, and gamma interferon, are expressed at increased levels in the nonlymphoid organs of relb−/− mice but have either normal or reduced expression in lymphoid tissues; in particular, isolated relb−/− macrophages are impaired in the production of TNF-α (60, 62). Since macrophages are normally the major source of TNF-α production, one wonders what the probable cellular source of TNF-α and other cytokines in the nonlymphoid organs of the relb−/− mice might be, what molecular mechanisms are involved, and, especially, how RelB may function in this process. In this report, we show that RelB is a key transcriptional suppressor of cytokine expression in fibroblasts and that its absence leads to the dysregulation of IL-1α, IL-1β, and TNF-α expression in relb−/− fibroblasts. We further demonstrate that RelB exerts its transcriptional suppressor function through the stabilization of IκBα protein. These data suggest new physiological roles for the NF-κB/Rel factors in the regulation of inflammatory and immune responses and may provide insights to uncover novel intra- and interfamily interactions of the NF-κB/Rel and IκB regulatory molecules.