Analysis Of Reaction Products Research Articles

Study of Catalyst Deactivation in Liquid-Phase Hydrogenation of 3-Nitrostyrene Over Au/Al2O3 Catalyst in Flow Reactor

For the first time, we report the results of the study of dynamics of the Au/Al2O3 catalyst deactivation during the selective liquid-phase 3-nitrostyrene (3-NS) hydrogenation in a fixed bed flow reactor. It is shown that the formation of carbonaceous deposits is the main reason of catalyst deactivation, while the leaching of gold from the Au/Al2O3 catalyst or enlargement of the gold particles has not been detected. The content of the carbon deposits on the spent catalyst at the inlet of the reactor is higher than at the outlet and increases as the initial concentration of 3-NS grows. The character of carbonaceous deposits allocation and analysis of reaction products point out to 3-vinylnitrosobenzene as the main source of the Au/Al2O3 catalyst deactivation coinciding with the speculation arising from the kinetic modeling.

Analysis of G3BP1 and VEZT Expression in Gastric Cancer and Their Possible Correlation with Tumor Clinicopathological Factors.

PurposeThis study aimed to analyze G3BP1 and VEZT expression profiles in patients with gastric cancer, and examine the possible relationship between the expressions of each gene and clinicopathological factors.Materials and MethodsExpression of these genes in formalin-fixed paraffin embedded (FFPE) tissues, collected from 40 patients with gastric cancer and 40 healthy controls, was analyzed. Differences in gene expression among patient and normal samples were identified using the GraphPad Prism 5 software. For the analysis of real-time polymerase chain reaction products, GelQuantNET software was used.ResultsOur findings demonstrated that both VEZT and G3BP1 mRNA expression levels were downregulated in gastric cancer samples compared with those in the normal controls. No significant relationship was found between the expression of these genes and gender (P-value, 0.4835 vs. 0.6350), but there were significant changes associated with age (P-value, 0.0004 vs. 0.0001) and stage of disease (P-value, 0.0019 vs. 0.0001). In addition, there was a direct relationship between VEZT gene expression and metastasis (P-value, 0.0462), in contrast to G3BP1 that did not demonstrate any significant correlation (P-value, 0.1833).ConclusionsThe results suggest that expression profiling of VEZT and G3BP1 can be used for diagnosis of gastric cancer, and specifically, VEZT gene could be considered as a biomarker for the detection of gastric cancer progression.

Nanoparticle-linked antagonist for leptin signaling inhibition in breast cancer.

AIMTo develop a leptin peptide receptor antagonist linked to nanoparticles and determine its effect on viability of breast cancer cells.METHODSThe leptin antagonist, LPrA2, was coupled via EDAC [1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide] to iron oxide nanoparticles (IONP-LPrA2) to increase its efficacy. IONP-LPrA2 conjugation was confirmed by Western blot and nanoparticle tracking analysis. Human triple negative breast cancer (TNBC) MDA-MB-231, HCC1806 and estrogen receptor positive (ER+) MCF-7 cells were analyzed for the expression of the leptin receptor, Ob-R. The effects of leptin and antagonist on levels of leptin-induced STAT3 phosphorylation and cyclin D1, cell cycle progression, cell proliferation, and tumorsphere formation in breast cancer cells were determined. Doses of the chemotherapeutics [cisplatin (Cis), cyclophosphamide (CTX), doxorubicin (Dox) and paclitaxel (PTX)] to effectively reduce cell viability were calculated. The effects of combination treatments of IONP-LPrA2 and chemotherapeutics on cell viability were determined.RESULTSWestern blot analysis of coupling reaction products identified IONP-LPrA2 at approximately 100 kD. IONP-LPrA2 significantly decreased leptin-induced pSTAT3 levels in HCC1806 cells and drastically decreased cyclin D1 levels in all cell lines. IONP-LPrA2 significantly reduced leptin-induced S phase progression and cell proliferation in all breast cancer cell lines and the formation of tumorspheres in MDA-MB-231 cells. Also, IONP-LPrA2 showed an additive effect on the reduction of breast cancer cell survival with chemotherapeutics. Cis plus IONP-LPrA2 produced a significant reduction in the survival of MDA-MB-231 and HCC1806 cells. CTX plus IONP-LPrA2 caused a significant decrease in the survival of MDA-MB-231 cells. Dox plus IONP-LPrA2 caused a marked reduction in the survival of HCC1806 cells. Although, PTX plus IONP-LPrA2 did not have a major effect on the viability of the breast cancer cells when compared to PTX alone.CONCLUSIONPresent data indicate that IONP-LPrA2 may be a useful adjuvant for chemotherapeutic treatment of breast cancer, particularly for TNBC which lacks targeted therapeutic options.

Mechanism and kinetics of the pyrolysis of β-pinene to myrcene

Myrcene, an important intermediate for the production of fine chemicals and pharmaceuticals, is mainly produced by the pyrolysis of β-pinene in the industry. The study of the direct pyrolysis of β-pinene was carried out without a catalyst and carrier gas at 573–873K and under low pressure. In order to clarify the reaction mechanism, the primary intermediates of β-pinene pyrolysis including myrcene and limonene were also used as raw materials for further pyrolysis. The identification of some small molecules and C10H16 isomers in the products proves that both decomposition reaction and ene reaction take place during the pyrolysis process. Based on the qualitative and quantitative analysis of reaction products, a reaction scheme for the pyrolysis of β-pinene was proposed. With appropriate simplification of the reaction scheme, a phenomenological kinetic model of the competitive parallel and consecutive first-order reaction was built, and exhibited good agreement with the experimental data. The activation energy (Ea) and pre-exponential factor (k0) for each pathway were also determined.

Deoxygenation of Triglycerides by Catalytic Cracking with Enhanced Hydrogen Transfer Activity

The efficient use of plant oils as alternative fuels was investigated by studying triglyceride deoxygenation in catalytic cracking using a fluid catalytic cracking catalyst with enhanced hydrogen transfer activity. Unsaturated triglyceride deoxygenation was rapid and complete, but small amounts of oxygenated products such as fatty acids, ketones, and aldehydes were produced from saturated triglycerides. Reaction product analysis showed that hydrogen transfer reactions between oxygenates and hydrocarbons produced by cracking fatty acid carbon chains caused hydrodeoxygenation even in the absence of hydrogen. Catalytic cracking of triglycerides with fatty acid carbon chains of various lengths showed that triglyceride deoxygenation is not affected by steric hindrance, and probably occurs on zeolite external surfaces, whereas secondary cracking of hydrocarbons occurs on the internal surfaces. We showed that catalytic cracking can be used for efficient conversion of triglycerides to hydrocarbons in the absence ...

Reactions of Ferrous Coproheme Decarboxylase (HemQ) with O2 and H2O2 Yield Ferric Heme b.

A recently discovered pathway for the biosynthesis of heme b ends in an unusual reaction catalyzed by coproheme decarboxylase (HemQ), where the Fe(II)-containing coproheme acts as both substrate and cofactor. Because both O2 and H2O2 are available as cellular oxidants, pathways for the reaction involving either can be proposed. Analysis of reaction kinetics and products showed that, under aerobic conditions, the ferrous coproheme-decarboxylase complex is rapidly and selectively oxidized by O2 to the ferric state. The subsequent second-order reaction between the ferric complex and H2O2 is slow, pH-dependent, and further decelerated by D2O2 (average kinetic isotope effect of 2.2). The observation of rapid reactivity with peracetic acid suggested the possible involvement of Compound I (ferryl porphyrin cation radical), consistent with coproheme and harderoheme reduction potentials in the range of heme proteins that heterolytically cleave H2O2. Resonance Raman spectroscopy nonetheless indicated a remarkably weak Fe-His interaction; how the active site structure may support heterolytic H2O2 cleavage is therefore unclear. From a cellular perspective, the use of H2O2 as an oxidant in a catalase-positive organism is intriguing, as is the unusual generation of heme b in the Fe(III) rather than Fe(II) state as the end product of heme synthesis.

Degradation of DEET and Caffeine under UV/Chlorine and Simulated Sunlight/Chlorine Conditions.

Photoactivation of aqueous chlorine could promote degradation of chlorine-resistant and photochemically stable chemicals accumulated in swimming pools. This study investigated the degradation of two such chemicals, N,N-diethyl-3-methylbenzamide (DEET) and caffeine, by low pressure ultraviolet (UV) light and simulated sunlight (SS) activated free chlorine (FC) in different water matrices. Both DEET and caffeine were rapidly degraded by UV/FC and SS/FC but exhibited different kinetic behaviors. The degradation of DEET followed pseudo-first-order kinetics, whereas the degradation of caffeine accelerated with reaction. Mechanistic study revealed that, under UV/FC, ·OH and Cl· were responsible for degradation of DEET, whereas ClO· related reactive species (ClOrrs), generated by the reaction between FC and ·OH/Cl·, played a major role in addition to ·OH and Cl· in degrading caffeine. Reaction rate constants of DEET and caffeine with the respective radical species were estimated. The imidazole moiety of caffeine was critical for the special reactivity with ClOrrs. Water matrix such as pH had a stronger impact on the UV/FC process than the SS/FC process. In saltwater matrix under UV/FC and SS/FC, the degradation of DEET was significantly inhibited, but the degradation of caffeine was much faster than that in nonsalty solutions. The interaction between Br- and Cl- may play an important role in the degradation of caffeine by UV/FC in saltwater. Reaction product analysis showed similar product patterns by UV/FC and SS/FC and minimal formation of chlorinated intermediates and disinfection byproducts.

Comparative analysis of NdCaCoO4 phase formation from cryogel and from solid state precursors

In order to identify the reasons of the complicated synthesis of NdCaCoO4 by the cryogel method, the phase formation processes during thermal processing of precursors were investigated by in-situ X-ray diffraction analysis, Rietveld refinement and energy dispersive X-ray analysis of reaction products and intermediates. Formation of NdCaCoO4 from the cryogel precursor and from the mixture of oxides and CaCO3 is observed at 1000–1100 °C. The complicated phase formation from the cryogel precursor is associated with the low reactivity of (Nd,Ca)CoO3 intermediate of the precursor thermolysis. Precipitation by NaOH/Na2CO3 instead of KOH/K2CO3 results in the reduction of NdCaCoO4 formation temperature to 800 °C. According to energy dispersive X-ray analysis, the coprecipitation of Nd, Ca and Co is accompanied by the capture of Na ions followed by the formation of NaxCoO2 phase at 600–700 °C. The enhanced reactivity of (Nd,Ca)CoO3 in this case could be attributed to the enhanced ion mobility due to the simultaneous formation of NaxCoO2, CoO and NdCaCoO4 (Hedvall effect).

Reaction path and product analysis of sodium-water chemical reactions using laser diagnostics

In a sodium-cooled fast reactor (SFR), liquid sodium is used as a coolant because of its excellent heat transport capability and a large safety margin to the boiling point (1153K) at the atmospheric pressure. On the other hand, it has strong chemical reactivity with water vapor. One of the design basis accidents of the SFR is the water leakage into the liquid sodium flow caused by a breach of heat transfer tubes. Therefore, the study on sodium-water chemical reactions is of importance for safety of SFR. The purpose of this study aims to clarify the gas phase sodium-water reaction path and reaction products quantitatively. The counter-flow diffusion experiment device was employed to analyze the reaction path and reaction products using laser diagnostics. sodium (Na), sodium dimer (Na2), water (H2O), sodium hydroxide (NaOH), sodium oxides (Na2O and NaO) and hydroxyl radical (OH) were measured using Raman spectroscopy, absorption spectroscopy, photo-fragmentation spectroscopy and laser induced fluorescence in the reaction field for the sodium-water vapor, sodium-oxygen and sodium-hydrogen reaction. Based on the measurement results by absorption spectroscopy, it was revealed that the sodium-oxygen reaction was faster than that of sodium-water. It was indicated that sodium-hydrogen reaction did not react noticeably with sodium from the measurement result as well. The main product of sodium-water reaction was determined to be NaOH and the sodium oxide was not notably measured compared with NaOH from the results by photo-fragmentation spectroscopy. The sodium oxide concentration ratio to NaOH was determined 2% with standard deviation of 3%. Its reaction path was also discussed using sodium-water, sodium-oxygen and sodium-hydrogen reaction analyses.

High-performance bio-based thermosetting bismaleimide resins utilizing difurfurylidenecyclopentanone and dicinnamylidene cyclopentanone

Difurfurylidenecyclopentanone (DFCPN) and dicinnamylidene cyclopentanone (DCCPN) were synthesized by aldol condensation reactions of cyclopentanone with furfural and cinnamaldehyde, both derived from renewable resources. The DFCPN and DCCPN were prepolymerized with 4,4′-bismaleimidodiphenylmethane (BMI) at 190 °C and then compression molded at 250 °C to produce cured DFCPN/BMI and DCCPN/BMI resins (DFCPN–BMI and DCCPN–BMI) with a molar ratio of 1/1, 1/2 or 1/3. The FT-IR spectral analysis of the cured resins and FD-MS analysis of the model reaction products using N-phenylmaleimide revealed that maleimide-rich addition copolymerization occurred. All of the cured resins except DCCPN–BMI 1/1 exhibited glass transition temperatures higher than 350 °C and 5 % weight loss temperatures higher than 450 °C, and their values increased with increasing BMI content. When cured resins with the same molar ratio were compared, DFCPN–BMI exhibited a higher flexural strength than DCCPN–BMI. Especially, DFCPN–BMI 1/1 exhibited extremely excellent flexural properties and heat resistance.

On-Line Mass Spectrometry for Ethanol Oxidation on Well-Defined Sn/Pt(hkl) Electrode Surfaces

Introduction Direct ethanol fuel cells (DEFCs) have attracted attention for their practical high energy density and low environmental burden. To generate electricity with high efficiency, ethanol needs to be completely oxidized to CO2. To date, Xia et al. have reported that the ethanol oxidation reaction (EOR) is sensitive to the topmost surface atomic arrangements of Pt [1]. Furthermore, Pt-based alloy catalysts have been studied extensively for EOR with low overpotentials. Therefore, it is important to clarify relations between EOR activity and topmost surface structures of Pt-based alloys to develop practical Pt-based alloy catalysts for DEFCs. In this study, we focused on Sn/Pt catalysts which have been studied well as alloy catalysts for EOR. On-line electrochemical mass spectrometry (OLEMS) should be effective for in-situ analysis of gaseous reaction products. Therefore, the relations of EOR onset potentials, potential-dependent gaseous products, and catalyst surface structures are investigated for well-defined Sn/Pt(hkl) surfaces prepared by vacuum depositions of Sn on Pt(hkl) single crystal substrates. Experimental Sample fabrication processes of the well-defined Sn/Pt(hkl) were conducted in ultra-high vacuum (UHV). Pt single crystal substrates (Pt(hkl): Pt(111), (110) and (100)) were cleaned by Ar+ sputtering and subsequent annealing at 1273 K in UHV. 0.1 nm-thick Sn was deposited onto the cleaned Pt(hkl) by an electron-beam evaporation method at room temperature, followed by annealing at 1000 K to flatten the topmost surfaces. The UHV-prepared Pt(hkl) and Sn/Pt(hkl) were transferred from UHV chambers to the electrochemical system set in a N2-purged glove box without being exposed to air. Cyclic voltammetry (CV) of the surfaces was conducted in N2-purged 0.1 M HClO4. Subsequently, ethanol was added to the solution to prepare a 2 M solution of ethanol in 0.1 M HClO4, and then CV and OLEMS measurements were performed. Results and Discussion The anodic currents of EOR for the Pt(hkl) and Sn/Pt(hkl) surfaces recorded in ethanol added HClO4 solutions are presented in Fig.1 (a). EOR onset potentials of the Sn/Pt(hkl) surfaces (solid curves) shift negatively in comparison to the corresponding Pt(hkl) surfaces (dashed curves). The negative potential shifts suggest that the Sn/Pt(hkl) surfaces exhibit higher EOR activity than the corresponding Pt(hkl) surfaces, probably because of the ensemble effect of the surface Pt and Sn atoms [2]. Fig.1 (b) shows the OLEMS results of the Sn/Pt(hkl) surfaces. The onset potentials of CO2 evolution are summarized in Table.1. Fig.1 (b) and Table.1 suggest that potential sweeps in the anodic direction (0.2 V to 0.9 V) cause CO2 evolution, and that the EOR onset potentials depend on the substrate atomic arrangements of Pt. In particular, the Sn/Pt(110) shows the lowest EOR onset potentials, as judged by EOR currents (Fig.1 (a)) and CO2 evolution (Fig.1 (b)). The results can be attributed to the effectiveness of Pt(110) steps against ethanol C-C bond cleavage [3] and the ensemble effect of the surface Pt and Sn atoms against CO poisoning of the Pt atoms [2]. Acknowledgement This work was partly supported by a Grant-in-Aid for scientific research (A) from the Japan society for the promotion of science (T. W.).

Direct Vacuum Inlet System Enabling Ultra-Sensitive in-Situ Analysis of Chemical Reaction Products

We present a first-of-its-kind vacuum inlet system enabling operation of vacuum analysis instruments, like mass spectrometers, directly in liquid or gaseous environments. Our inlet system overcomes the limitations of differential pumping while maintaining an ultra-fast time-response and delivering up to 1000 times higher sensitivity than conventional technologies [1]. We are thus able to perform quantitative analysis of chemical reaction products with unprecedented sensitivity on millisecond time-scales. Across many scientific and industrial fields, it is a challenge to analyse chemical reaction products with high sensitivity and fast time-response. This is especially true in systems related to electrochemical energy conversion and storage, such as batteries and fuel cells, where accurate monitoring of fast and intermediate reaction phenomena often reveals key insights. At present, in-situ detection of electrochemical reaction products in liquid (most often aqueous) electrolytes is achieved by using a porous membrane inlet system together with differential pumping stages coupled with a mass spectrometer, a technique known in literature as Differential Electrochemical Mass Spectrometry (DEMS) [2]. However, by having an inlet system operating with differential pumping, vast amounts of both analyte and solvent are pumped away before entering the mass spectrometer. This translates into a significant drop in sensitivity and a large background-signal in the mass spectrometer due to rapid solvent evaporation. Furthermore, since DEMS systems are not commercially available, they presently only exist as custom-made and expensive instruments in a few research laboratories. Here we present a novel vacuum inlet system, allowing mass spectrometers to operate directly in a liquid electrolyte without the use of differential pumping, thus delivering a 1000-fold sensitivity increase over conventional techniques, while maintaining an ultra-fast time-response. The inlet system consists of a disposable micro-fabricated membrane chip made of silicon, which forms a stable permeable interface between the vacuum of a mass spectrometer and the liquid of an electrochemical test environment. Due to the direct injection nature of this system no analyte is lost to differential pumping, which increases sensitivity of the system tremendously and makes calibration for quantitative measurements easier. In addition, the full analysis system is built more compactly and with fewer components than conventional DEMS systems, making it a significantly cheaper instrument. Finally, this inlet system operates equally well in liquid and gaseous test environments, making it highly versatile and easy to use. The capabilities of this analysis system are showcased by various examples, including electrochemical water-splitting at low overpotentatial and low surface area CO-stripping. It is shown how the evolution of hydrogen and oxygen can be quantified in-situ at Faradaic currents on the order of 10 nA. In comparison, conventional techniques are capable of achieving detections down to about 10 µA. In addition it is shown, that it is possible to make a quantitative in-situ detection of < 1 % of a monolayer of surface adsorbed CO being electrochemically stripped off an electrode at standard potential scan-rates of 50 mV/s.

Factors Controlling the Chemoselectivity in the Oxidation of Olefins by Nonheme Manganese(IV)-Oxo Complexes.

We report the oxidation of cyclic olefins, such as cyclohexene, cyclohexene-d10, and cyclooctene, by mononuclear nonheme manganese(IV)-oxo (Mn(IV)O) and triflic acid (HOTf)-bound Mn(IV)O complexes. In the oxidation of cyclohexene, the Mn(IV)O complexes prefer the C-H bond activation to the C═C double bond epoxidation, whereas the C═C double bond epoxidation becomes a preferred reaction pathway in the cyclohexene oxidation by HOTf-bound Mn(IV)O complexes. In contrast, the oxidation of cyclohexene-d10 and cyclooctene by the Mn(IV)O complexes occurs predominantly via the C═C double bond epoxidation. This conclusion is drawn from the product analysis and kinetic studies of the olefin oxidation reactions, such as the epoxide versus allylic oxidation products, the formation of Mn(II) versus Mn(III) products, and the kinetic analyses. Overall, the experimental results suggest that the energy barrier of the C═C double bond epoxidation is very close to that of the allylic C-H bond activation in the oxidation of cyclic olefins by high-valent metal-oxo complexes. Thus, the preference of the reaction pathways is subject to changes upon small manipulation of the reaction environments, such as the supporting ligands and metal ions in metal-oxo species, the presence of HOTf (i.e., HOTf-bound Mn(IV)O species), and the allylic C-H(D) bond dissociation energies of olefins. This is confirmed by DFT calculations in the oxidation of cyclohexene and cyclooctene, which show multiple pathways with similar rate-limiting energy barriers and depending on the allylic C-H bond dissociation energies. In addition, the possibility of excited state reactivity in the current system is confirmed for epoxidation reactions.

Identification of novel reaction products of methylene-bis-phenylisocyanate (“MDI”) with oxidized glutathione in aqueous solution and also during incubation of MDI with a murine hepatic S9 fraction

Methylene diphenyl diisocyanate (MDI) is an important industrial chemical and asthmagenic respiratory sensitizer, however its metabolism remains unclear. In this study we used LC-MS and LC-MS/MS to identify novel reaction products of MDI with oxidized glutathione (GSSG), including an 837m/z [M+H]+ ion corresponding to GSSG bound (via one of its N-termini) to partially hydrolyzed MDI, and an 863m/z [M+H]+ ion corresponding to GSSG cross-linked by MDI (via its two γ-glutamine N-termini). Further studies with heavy isotope labeled and native reduced glutathione (GSH) identified an [M+H]+ ion corresponding to previously described mono(GSH)-MDI, and evidence for “oligomeric” GSH-MDI conjugates. This study also investigated transformational changes in MDI after incubation with an S9 fraction prepared from murine liver. LC-MS analyses of the S9 reaction products revealed the formation of [M+H]+ ions with m/z's and retention times identical to the newly described GSSG-MDI (837 and 863) conjugates and the previously described mono(GSH)-MDI conjugate. Together the data identify novel biological transformations of MDI, which could have implications for exposure-related health effects, and may help target future in vivo studies of metabolism.

An investigation on NO removal by wet scrubbing using NaClO2 seawater solution.

The experiments were conducted to investigate the NO removal by wet scrubbing using NaClO2 seawater solution in a cyclic scrubbing mode. Results show that, when the concentration of NaClO2 in scrubbing solution is higher than 10 mM, a complete removal of NO can be achieved during the cyclic scrubbing process. The breakthrough time for seawater with 15 mM NaClO2 is enhanced by 34.3 % compared with that for NaClO2 freshwater. The extension of the breakthrough time for NaClO2 seawater is mainly ascribed to the improved utilization of NaClO2 in the solution. The good buffering ability of seawater could suppress the acidic decomposition of NaClO2 into ClO2 effectively. The analysis of reaction products indicates that the main anions in the spent liquor are chloride ions and nitrate ions. The calculation of NaClO2 utilization according to the ion chromatography also agrees well with the experimental results of breakthrough times.

Pechini Synthesis of LiFeBO3/C and Application As Cathode Material in Lithium Ion Batteries

The development of new cathode materials with high capacity, good stability, and high safety is important for the future improvement of lithium batteries. While most cathodes in commercial cells uses layered oxides, materials containing polyanion groups such as phosphate (PO4), silicates (SiO4), and borates (BO3) have generated interest because of the inherent stability of the polyanion group against oxygen lost [1-4]. There is a need for cathode materials working at higher output voltages with higher practical capacities. Borates could be good alternative to phosphates by having the lower weight BO3 -3 group instead of PO4 -3, but keeping the advantage of the linking anion group giving higher operating voltage and enhanced structural stability [5]. In this research work the synthesis of LiFeBO3/C composite was achieved using Pechini sol-gel method. In order to determine the influence of the carbon content in the formation of composite LiFeBO3/C, different molar ratio compositions of iron precursor and citric acid (Fe:CA) such as 1:0.1, 1:0.5, 1:1 and 1:2 were prepared. Starting precursors were salts of LiNO3, Fe(NO3)3·9H2O, H3BO3 and citric acid/ethylene glycol were used for polyesterification reaction. Aqueous solutions containing appropriate amounts of salts were poured into a mixture of citric acid and ethylene glycol solution. Mixture was then heat treated under reflux at 80°C until gel formation. In order to determine heating temperatures for Pechini sol-gel samples, simultaneous thermal analysis TGA-DTA was carried out. Fresh samples were preheated at 300°C under air to eliminate volatile matter. Resulting powders were ground and formed into pellets for reaction between 550 to 650°C under nitrogen atmosphere. Morphological and microstructural characterization were carried out with field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), textural analysis by N2 physisorption with BET method; and crystalline phases were determined with X-ray powder diffraction (XRD); the application of materials as cathodes in lithium ion batteries was evaluated through electrochemical charge discharge experiments. Electrodes were prepared using a mixture of each synthesized materials, conductive carbon and PVDF binder. CR2032 coin cells were assembled inside a glove box under Ar atmosphere, using LiPF6electrolyte and Li° as anode. Experiments were performed using a MacPile II by Biologic. Thermal analysis of sol-gel reaction products exhibited an exothermic even between 550 and 600°C attributed to the crystallization of the borates. It has been found that the variation of iron:citric acid (Fe:CA) molar ratio yielded different particle size and crystallinity of the composite. The 1:1 and 1:2 molar ratio compositions of Fe:CA, and temperatures between 550-650°C for 10h were the experimental conditions that produced a single phase material with improved characteristics such as small particle size, crystallinity and porosity. Mesoporous materials were obtained, with specific surface areas of 4.96 and 36.06 m2 g-1 for composites with Fe:CA molar ratio of 1:1 (LFB1) and 1:2 (LFB2) respectively. Morphology of LFB1 samples correspond to particles with irregular shapes and size about 187.8-361.7 nm, in the other hand samples of LFB2 contain primary spherical particles forming clusters, with particle sizes between 42 and 78 nm, this can be attributed to the effect of residual carbon within samples since this inhibits particle grown and also allows contact among particles, improving electrical conductivity. LFB1 composite tested in lithium cell present a specific capacity of 202 mAhg-1 during the first 10th discharge cycles with columbic efficiency of 95 %. LFB2 showed a specific capacity of 213 mAh g-1 during discharge, corresponding to 97% of theoretic capacity, using current densities of 5 and 10 mA g-1. A specific capacity of 198 mAh g-1 was obtained during discharge, corresponding to 90% of theoretic capacity, using current density of 50 mA g-1. These results seem favorable for future application of the material in lithium ion batteries. Keywords: Lithium-ion batteries; cathode material; Pechini sol-gel; borates; LiFeBO3

Mechanism for Six-Electron Aryl-N-Oxygenation by the Non-Heme Diiron Enzyme CmlI.

The ultimate step in chloramphenicol (CAM) biosynthesis is a six-electron oxidation of an aryl-amine precursor (NH2-CAM) to the aryl-nitro group of CAM catalyzed by the non-heme diiron cluster-containing oxygenase CmlI. Upon exposure of the diferrous cluster to O2, CmlI forms a long-lived peroxo intermediate, P, which reacts with NH2-CAM to form CAM. Since P is capable of at most a two-electron oxidation, the overall reaction must occur in several steps. It is unknown whether P is the oxidant in each step or whether another oxidizing species participates in the reaction. Mass spectrometry product analysis of reactions under (18)O2 show that both oxygen atoms in the nitro function of CAM derive from O2. However, when the single-turnover reaction between (18)O2-P and NH2-CAM is carried out in an (16)O2 atmosphere, CAM nitro groups contain both (18)O and (16)O, suggesting that P can be reformed during the reaction sequence. Such reformation would require reduction by a pathway intermediate, shown here to be NH(OH)-CAM. Accordingly, the aerobic reaction of NH(OH)-CAM with diferric CmlI yields P and then CAM without an external reductant. A catalytic cycle is proposed in which NH2-CAM reacts with P to form NH(OH)-CAM and diferric CmlI. Then the NH(OH)-CAM rereduces the enzyme diiron cluster, allowing P to reform upon O2 binding, while itself being oxidized to NO-CAM. Finally, the reformed P oxidizes NO-CAM to CAM with incorporation of a second O2-derived oxygen atom. The complete six-electron oxidation requires only two exogenous electrons and could occur in one active site.

Occurence of Bordetella bronchiseptica in domestic cats with upper respiratory tract infections.

Bordetella bronchiseptica is a widespread Gram-negative pathogen occurring in different mammal species. It is known to play a role in the etiology of infectious atrophic rhinitis of swine, canine kennel cough, respiratory syndromes of cats, rabbits and guinea pigs, and sporadic human cases have also been reported. The aim of this article is to present the occurrence of infections caused by these bacteria in domestic cats with respiratory symptoms, as well as to conduct a molecular analysis of the flaA gene B. bronchiseptica for the purpose of ascertaining whether cats become infected with one or more bacteria strains. B. bronchiseptica was isolated from the respiratory system of 16 out of 35 domestic cats with symptoms of respiratory tract infections. Polymorphism analysis of polymerase chain reaction products of B. bronchiseptica flaA was performed to reveal the possible differences in nucleotide sequences of the flagellin gene. The phylogenetic analysis of nucleotide sequences obtained during PCR indicated that the isolates of bacteria from our own studies are characterised by 100% homology of the analysed fragment of the flaA gene, which suggests maintenance of a single genotype of these microorganisms in the cat population. Moreover, the bacteria revealed full homology with reference strain B. bronchiseptica ATCC 4617, and 99.4% homology with strain B. parapertussis ATCC 15311. This indicates that the PCR optimised for the Bordetella spp. flaA gene, combined with sequencing of amplicons obtained in PCR, is an effective diagnostic method allowing differentiation of Bordetella spp. type microorganisms.

Altered Secretory Activity of APE1/Ref-1 D148E Variants Identified in Human Patients With Bladder Cancer.

Purpose:Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein involved in DNA repair and redox modulation. Recently, serum and urinary APE1/Ref-1 levels were reported to be increased in patients with bladder cancer. Genetic variations of APE/Ref-1 are associated with the risk of cancer. However, the effect of APE1/Ref-1 variants on its secretory activity is yet unknown.Methods:APE1/Ref-1 variants were evaluated by DNA sequencing analysis of reverse transcription polymerase chain reaction products in coding DNA sequences (CDS) of APE1/Ref-1 in bladder tissue samples from patients with bladder cancer (n=10). Secretory activity of APE1/Ref-1 variants was evaluated with immunoblot and enzyme-linked immunosorbent assay of the culture medium supernatants.Results:Four different substitution mutants (D148E, I64V/D148E, W67R/D148E, and E86G/D148E) of APE1/Ref-1 were identified in bladder cancer specimens. However, deletion mutants of APE1/Ref-1 CDS were not found. The secretory activity of the APE1/Ref-1 variants (D148E, I64V/D148E, and E86G/D148E) was increased compared to that of wild type APE1/Ref-1. Furthermore, the secretory activity in basal or hyperacetylated conditions was much higher than that in APE1/Ref-1 D148E-transfected HEK293 cells.Conclusions:Taken together, our data suggest that the increased secretory activity of D148E might contribute to increased serum levels of APE1/Ref-1 in patients with bladder cancer.

A Novel Glycoside Hydrolase Family 5 β-1,3-1,6-Endoglucanase from Saccharophagus degradans 2-40T and Its Transglycosylase Activity.

In this study, we characterized Gly5M, originating from a marine bacterium, as a novel β-1,3-1,6-endoglucanase in glycoside hydrolase family 5 (GH5) in the Carbohydrate-Active enZyme database. The gly5M gene encodes Gly5M, a newly characterized enzyme from GH5 subfamily 47 (GH5_47) in Saccharophagus degradans 2-40(T) The gly5M gene was cloned and overexpressed in Escherichia coli Through analysis of the enzymatic reaction products by thin-layer chromatography, high-performance liquid chromatography, and matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry, Gly5M was identified as a novel β-1,3-endoglucanase (EC 3.2.1.39) and bacterial β-1,6-glucanase (EC 3.2.1.75) in GH5. The β-1,3-endoglucanase and β-1,6-endoglucanase activities were detected by using laminarin (a β-1,3-glucan with β-1,6-glycosidic linkages derived from brown macroalgae) and pustulan (a β-1,6-glucan derived from fungal cell walls) as the substrates, respectively. This enzyme also showed transglycosylase activity toward β-1,3-oligosaccharides when laminarioligosaccharides were used as the substrates. Since laminarin is the major form of glucan storage in brown macroalgae, Gly5M could be used to produce glucose and laminarioligosaccharides, using brown macroalgae, for industrial purposes. In this study, we have discovered a novel β-1,3-1,6-endoglucanase with a unique transglycosylase activity, namely, Gly5M, from a marine bacterium, Saccharophagus degradans 2-40(T) Gly5M was identified as the newly found β-1,3-endoglucanase and bacterial β-1,6-glucanase in GH5. Gly5M is capable of cleaving glycosidic linkages of both β-1,3-glucans and β-1,6-glucans. Gly5M also possesses a transglycosylase activity toward β-1,3-oligosacchrides. Due to the broad specificity of Gly5M, this enzyme can be used to produce glucose or high-value β-1,3- and/or β-1,6-oligosaccharides.