Tertiary Mixtures Research Articles

Thyroid Follicular Lesions Induced by Oral Treatment for 2 Years with 2,3,7,8-Tetrachlorodibenzo-p-dioxin and Dioxin-like Compounds in Female Harlan Sprague-Dawley Rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and structurally-similar dioxin-like compounds affect thyroid function and morphology and thyroid hormone metabolism in animals and humans. The National Toxicology Program conducted eight 2-year gavage studies in female Harlan Sprague-Dawley rats to determine the relative potency of chronic toxicity and carcinogenicity of TCDD, 3,3',4,4',5-pentachlorobiphenyl (PCB126), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), 2,3',4,4',5-pentachlorobiphenyl (PCB118), 2,2',4,4',5,5'-hexachloro-biphenyl (PCB153), a tertiary mixture of TCDD/PCB126/PeCDF, and two binary mixtures (PCB126/PCB153 and PCB126/PCB118). Administration of these compounds was associated with increased incidences of thyroid follicular cell hypertrophy, variably observed in the 14-, 31-, and 53-week interim and 2-year sacrifice groups. In all studies, the incidences of follicular cell adenoma and carcinoma were not increased. Decreased levels of serum thyroxine were primarily noted in the 14-or-later -week interim groups of all chemicals. Serum triiodothyronine (T3) levels were increased in the TCDD, PCB126, PeCDF, TCDD/PCB126/PeCDF, and PCB126/PCB153 studies, while decreased levels were noted in the PCB153 and PCB126/PCB118 studies. TCDD, PCB126, PCB126/PCB153, and PCB126/PCB118 increased levels of serum thyroid-stimulating hormone almost in a dose-dependent manner in the 14-week groups. These data suggest that although dioxin-like compounds alter thyroid hormones and increase follicular cell hyperplasia, there is not an increase in thyroid adenoma or carcinoma in female Sprague-Dawley rats.

Effects of cell condition, pH, and temperature on lead, zinc, and copper sorption to Acidithiobacillus caldus strain BC13

This study describes the effects of cell condition, pH, and temperature on lead, zinc, and copper sorption to Acidithiobacillus caldus strain BC13 with a Langmuir model. Copper exhibited the highest loading capacity, 4.76±0.28mmolg−1, to viable cells at pH 5.5. The highest kL (binding-site affinity) observed was 61.2±3.0Lmmol−1 to dehydrated cells at pH 4.0. The pHs that maximized loading capacities and binding-site affinities were generally between 4.0 and 5.5, where the sum of free-proton and complexed-metal concentrations was near a minimum. Of additional importance, lead, zinc, and copper sorbed to viable cells at pH values as low as 1.5. Previous studies with other acidithiobacilli did not measure viable-cell sorption below pH 4.0. In separate experiments, desorption studies showed that far less copper was recovered from viable cells than any other metal or cell condition, suggesting that uptake may play an important role in copper sorption by At. caldus strain BC13. To reflect an applied system, the sorption of metal mixtures was also studied. In these experiments, lead, zinc, and copper sorption from a tertiary mixture were 40.2±4.3%, 28.7±3.8%, and 91.3±3.0%, respectively, of that sorbed in single-metal systems.

CHEMICAL TESSELLATIONS — RESULTS OF BINARY AND TERTIARY REACTIONS BETWEEN METAL IONS AND FERRICYANIDE OR FERROCYANIDE LOADED GELS

In our recent letter [de Lacy Costello et al., 2009] we described the formation of spontaneous complex tessellations of the plane constructed in simple chemical reactions between drops of metal salts and ferricyanide or ferrocyanide loaded gels. In this paper, we provide more examples of binary tessellations and extend our analysis to tessellations constructed via tertiary mixtures of reactants. We also provide a classification system which describes the tessellation based on the reactivity of the metal salt with the substrate and also the cross-reactivity of the primary products. This results in balanced tessellations where both reactants have equal reactivity or unbalanced tessellations where one reactant has a lower reactivity with the gel. The products can also be partially or fully cross reactive which gives a highly complex tessellation. The tessellations are made up of colored cells (corresponding to different metal ferricyanides or ferrocyanides) separated by bisectors of low precipitate concentration. The tessellations constructed by these reactions constitute generalized Voronoi diagrams. In the case of certain binary or tertiary combinations of reactants where the diffusion/reaction rates differ, then multiplicatively weighted crystal growth Voronoi diagrams are constructed. Where one reactant has limited or no reactivity with the gel (or the products are cross reactive) then the fronts originating from the reactive metal ions cross the fronts originating from the partially reactive metal ions. The fronts can annihilate in the formation of a second Voronoi diagram relating to the relative positions of the reactive drops. Therefore, two or more generalised or weighted Voronoi diagrams can be calculated in parallel by these simple chemical systems. However when these reactions were used to calculate an additively weighted Voronoi diagram (the reaction was initiated at different time intervals) the diagram constructed did not correspond to the theoretical calculation. We use the failure of these reactions to construct an additively weighted Voronoi diagram to prove a mechanism of substrate competition for bisector formation. These tessellations are an important class of pattern forming reactions and are useful in modeling natural pattern forming phenomena in addition to being a great resource for scientific demonstrations.

Application of Phasor Plots to Analysis of Fluorophore Heterogeneity, Excited State Reactions and Protein Conformations

Phasor plots provide a simple graphical method to visualize and quantify time resolved fluorescence data, obtained using either frequency or time domain methods, independent of model constraints. Using the phase and modulation approach, the phasor plot converts raw data at a single frequency to a vector. Single exponential decays appear on the universal circle (semicircle with radius 0.5 and center 0.5, 0) whereas decays due to multiple exponentials appear as points inside the universal circle. This method has been successfully applied to fluorescence lifetime imaging microscopy (FLIM) wherein the data are typically collected at only one frequency. Applications of phasor plots in FLIM studies have, to date, been largely limited to FRET studies in cells. We have extended the application of phasor plots to several in vitro systems. Specifically, we have analyzed frequency-domain data of binary and tertiary mixtures of non-interacting, monoexponential-decay fluorophores and intrinsic protein fluorescence using the phasor plot approach. Phasor points from binary mixtures of varying composition lie along the line connecting the individual component points on the universal circle, while tertiary mixture points fall in a triangle between the individual vectors. Molecular interactions such as protein dissociation, protein-ligand interaction, denaturation, and energy transfer resulted in changes in the position of the vector point allowing for a rapid, graphical representation of these complex reactions. Data at a single frequency may be recorded rapidly allowing resolution of kinetic processes that would be difficult to monitor using complete multifrequency approaches. The combined results demonstrate the value of the phasor plot method to in vitro lifetime analysis. This work was supported in part by a grant from Allergan, Inc.

Toxicity of three phenolic compounds and their mixtures on the gram-positive bacteria Bacillus subtilis in the aquatic environment

Although phenolic compounds are intensively studied for their toxic effects on the environment, the toxicity of catechol, resorcinol and hydroquinone mixtures are still not well understood because most previous bioassays are conducted solely using single compound based on acute tests. In this work, the adverse effect of individual phenolic compounds (catechol, resorcinol and hydroquinone) and the interactive effect of the binary and tertiary mixtures on Bacillus subtilis ( B. subtilis) using microcalorimetric method were examined. The toxicity of individual phenolic compounds follows the order catechol > resorcinol > hydroquinone with their respective half inhibitory concentration as 437, 728 and 934 µg mL − 1. The power–time curve of B. subtilis growth obtained by microcalorimetry is in complete agreement with the change in turbidity of B. subtilis against time, demonstrating that microcalorimetric method agrees well with the routine microbiological method. The toxicity data obtained from phenolic compound mixtures show that catechol and hydroquinone mixture possess synergistic effect while the other mixtures display additive joint actions. Furthermore, the concentration addition (CA) and independent action (IA) models were employed to predict the toxicities of the phenolic compounds. The experimental results of microcalorimetry show no significant difference on the toxicity of the phenolic compound mixtures from that predicted by CA. However, IA prediction underestimated the mixture effects in all the experiments.

Reproductive Lesions in Female Harlan Sprague-Dawley Rats Following Two-Year Oral Treatment with Dioxin and Dioxin-like Compounds

Results from previously published animal studies suggest that prenatal and postnatal exposure to dioxin and dioxin-like compounds (DLCs) may profoundly affect the reproductive system of both sexes via endocrine disruption. In the present work, we evaluate the toxicity and carcinogenicity of various DLCs, with an emphasis on their effect on the reproductive organs, induced by chronic exposure of female adult Harlan Sprague-Dawley rats. This investigation represents part of an initiative of the National Toxicology Program to determine the relative potency of chronic toxicity and carcinogenicity of polychlorinated dioxins, furans, and biphenyls. For fourteen, thirty-one, or fifty-three weeks or for two years, animals were administered by gavage 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); 3,3',4,4',5-pentachlorobiphenyl (PCB126); 2,3,4,7,8-pentachlorodibenzofuran (PeCDF); 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153); 2,3',4,4',5-pentachlorobiphenyl (PCB118); a tertiary mixture of TCDD, PCB126, and PeCDF; a binary mixture of PCB126 and 153; or a binary mixture of PCB126 and PCB118. The ranges of treatment-related changes in the reproductive system included chronic active inflammation in the ovary that occurred in the 1,000 and 3,000 microg/kg core groups (two-year exposure) of PCB153 and in the 300 ng/3,000 microg/kg core group of binary mixture of PCB126 and PCB153. Increases in the incidence of acute and/or chronic active inflammation of the uterus were observed in all dosed groups, including the stop-exposure group (withdrawal after thirty-week exposure) of PeCDF and the 1,000 microg/kg and/or higher group dosed with PCB153. The incidence of cystic endometrial hyperplasia was marginally increased in the 92 PeCDF ng/kg group at two years. The incidence of squamous metaplasia was significantly increased in the 44 ng/kg and higher dose group, including the stop-exposure group. The incidence of uterine squamous cell carcinoma was significantly or marginally increased in the 6 ng/kg core and 100 ng/kg stop-exposure groups of TCDD and in the 300 ng/300 microg/kg core group that received the binary mixture of PCB126 and 153. The incidence of uterine carcinoma was marginally increased in the 92 ng/kg PeCDF group at two years and clearly increased in the 1,000 and 4,600 microg/kg PCB118 core group and the 4,600 microg/kg stop group. In the studies of PCB 126, the tertiary mixture, and the binary mixture of PCB126 and PCB118, no increased incidence of any change occurred in the reproductive systems. The range of changes seen with the different compounds suggests that more than one mechanism may have been involved in promoting the female reproductive pathology.

Quantitative study of solid-state acid–base reactions between polymorphs of flufenamic acid and magnesium oxide using X-ray powder diffraction

The purpose of this study is to investigate solid-state acid–base reactions between polymorphs of flufenamic acid (FFA) and magnesium oxide (MgO) using X-ray powder diffraction (XRPD). Polymorphs of FFA were blended with MgO and stored under conditions of 96.5% RH and 89% RH at 40 °C. The disappearance of FFA and production of magnesium flufenamate were monitored by XRPD. It was observed that the reactions between FFA and MgO proceeded following the Jander equation. Form I of FFA is more reactive with MgO than Form III. Differential accessibility of reactive groups is hypothesized as one of the reasons that Form I is more reactive than Form III. It was noted that the reaction between FFA and MgO could be mitigated by adding another acidic excipient such as polyacrylic acid to prevent the acid–base reaction with FFA. The effectiveness of polyacrylic acid was impacted by the mixing order of the tertiary mixture. Mixing polyacrylic acid and MgO first provided the most significant protection. In conclusion, solid-state acid–base reactions could be investigated using XRPD. Different forms may have distinct reactivity. Acid–base reactions in the solid state could be mitigated through the addition of another “shielding” excipient.

Poly(3-methylthiophene)/palladium sub-micro-modified sensor electrode. Part II: Voltammetric and EIS studies, and analysis of catecholamine neurotransmitters, ascorbic acid and acetaminophen

Promising voltammetric sensors based on the modification of Pt and poly(3-methylthiophene) (PMT) electrodes with Pd nanoparticles were achieved for the determination of catecholamine neurotransmitters, ascorbic acid and acetaminophen. Electrochemistry of the indicated compounds was studied at these electrodes and interesting electrocatalytic effects were found. Furthermore, simple, easily prepared one electrochemical step Pd-modified Pt electrode (Pt/Pd) is reported for the first time. Cyclic voltammetry (CV) and chronocoulometry (CC) were used for the determination of the apparent diffusion coefficients in different electrolytes at these electrodes and the values are in the range from 10−4 to 10−5cm2s−1. Furthermore, it was found that the method of polymer formation had a substantial effect on the synergism between the polymer film and the loaded metal particles towards the oxidation of dopamine (DA) in different supporting electrolytes. This was confirmed by the CV, CC and EIS (electrochemical impedance spectroscopy) as well as SEM (Scanning Electron Microscopy) results. Pt and PMT electrodes modified with Pd nanoparticles showed excellent results for the simultaneous determination of tertiary and quaternary mixtures of the studied compounds.

Morphology and Mechanical Properties of Bicontinuous Gels of Agarose and Gelatin and the Effect of Added Lipid Phase

This study examines the structural properties of binary and tertiary mixtures made of the cold-setting biopolymers agarose and gelatin and a lipid phase with solid or liquid-like viscoelasticity. The working protocol included the techniques of small-deformation dynamic oscillation on shear, modulated differential scanning calorimetry and scanning electron microscopy, and theoretical modeling that adapted ideas of relating the morphology to the elastic modulus of synthetic polyblends and block polymers. The experimental setting was designed to encourage extensive phase separation in the binary gel of agarose and gelatin whose mechanical properties were rationalized on the basis of a bicontinuous blending law. The presence of two continuous phases allowed the slower-gelling component (gelatin) to exhibit favorable relative affinity for the solvent with increasing concentrations of the protein in the system. This is an unexpected outcome that contradicts the central finding of a single value of the p factor observed in the distribution of solvent between the continuous matrix and discontinuous inclusions of deswelled binary gels reported earlier in the literature. The incorporation of a lipid phase of effectively zero elastic modulus or in excess of 10(8) Pa in the composite aqueous gel weakens or reinforces the matrix accordingly. The elastic moduli and morphology of the tertiary blend were related to changing the relative phase volumes of components using analytical expressions of isotropically dispersed soft or rigid filler particles in a polymeric matrix.

Antimicrobial Peptide C18G binds to Lipid Bilayers in a Lipid Composition Dependent Manner

Antimicrobial peptides serve as one of the first lines of defense in the immune systems of higher organisms. These peptides specifically target and neutralize infecting bacteria in the host organism while exhibiting little or no toxic effect on host cells. The peptide C18G is a highly cationic, amphiphilic peptide derived from the C-terminal sequence of the human protein platelet factor 4 (involved in blood coagulation and wound repair) exhibited antibacterial activity against both gram positive and gram negative bacteria. Using a modified C18G sequence that did not affect antimicrobial efficacy (Y3 changed to W), the binding affinity of the peptide to model membranes was performed using fluorescence spectroscopy. As anticipated, the binding of C18G to lipid bilayers allowed the Trp side chain to localize to a more hydrophobic environment resulting in a blue shift of Trp emission lambda max and spectral barycenter, concomitant with a narrowing of the emission spectrum and and increase in the overall emission intensity. Binding to lipid vesicles composed of binary and tertiary mixtures of POPC:POPG and POPC:POPG:POPE showed a dramatic lipid dependence on binding affinity, with the tightest binding to the most anionic compositions. Increasing the POPE composition enhanced peptide binding but to a lesser degree compared to the anionic POPG. Fluorescence quenching experiments using the aqueous quencher acrylamide confirmed the decreased exposure of the Trp to the aqueous milieu. Dye release assays were used to monitor lipid composition effects on the ability of C18G to permeabilize lipid vesicles. Circular dichroism spectroscopy indicated a conformational change from a disordered to an alpha-helical secondary structure when the peptide interacts with detergent micelles or anionic lipid vesicles.

The development of a membrane-covered microelectrode array gas sensor for oxygen and carbon dioxide measurement

The simultaneous electrochemical reduction of oxygen and carbon dioxide at −1.5 and −2.5 V vs. Ag, respectively, has been investigated on two different, gold microelectrode arrays, one with 37 electrodes of diameter 20 μm and the other with 256 electrodes of diameter 5 μm. The arrangement of a practical sensor design incorporating a porous polytetrafluoroethylene (PTFE) membrane-covered gold microelectrode array is described for the simultaneous measurement of O 2 and CO 2 . Linear sweep voltammetry and chonoamperometry techniques were applied in these studies, using propylene carbonate (PC) as the electrolyte. It was demonstrated that short voltage pulses (50 ms) and gold microelectrode arrays can be successfully used, in a practical sensor design, to interrogate the electrochemical reduction of both oxygen and carbon dioxide individually, and measure their concentrations in tertiary gas mixtures.

Investigation of sorption capacity of pumice for SO 2 capture

The sorption capacity of pumice has been investigated for the removal of SO 2 from binary and tertiary mixtures with N 2 and N 2 + CO 2, respectively. The influence of the presence of water on the adsorption of SO 2 has also been analyzed by moisturizing the adsorbent at different levels within the limits of applicability of Henry's law. SO 2 adsorption capacity of dry pumice was found as 16.26 mg SO 2 g −1 pumice while for adsorption on moisturized pumice (22 wt% moisture) it was 33.4 mg SO 2 g −1 pumice at 293 ± 2 K. When co-adsorption of CO 2 and SO 2 was carried out SO 2 adsorption on dry pumice was slightly reduced, but this counter effect of CO 2 was gradually removed by increasing water content of the adsorbent. Moreover, the acidic character of the adsorption products reduced the durability of pumice when it was moisturized.

Toxicity of Nonylphenol, Nonylphenol Monoethoxylate, and Nonylphenol Diethoxylate and Mixtures of these Compounds to Pimephales promelas (Fathead Minnow) and Ceriodaphnia dubia

Three phenolic compounds were evaluated for their toxicity to the freshwater species Pimephales promelas (fathead minnow) and Ceriodaphnia dubia. Acute toxicity tests using nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), and nonylphenol diethoxylate (NP2EO) were conducted using the single chemicals and as binary and tertiary mixtures. These compounds frequently coexist in surface waters as the result of discharges from wastewater treatment plants that are inefficient at removing nonylphenolic compounds. The mean lethal concentrations (LC(50)s) for NP, NP1EO, and NP2EO to the fathead minnow were 136, 218, and 323 microg/L, respectively. The LC(50)s of NP, NP1EO, and NP2EO to C. dubia were 92.4, 328, and 716 microg/L, respectively. The degree of toxic interactions was evaluated by converting mixture LC(50) estimates to toxic units (TUs). When exposed to fathead minnows, the binary mixtures of NP plus NP1EO and NP plus NP2EO produced 0.87 and 0.70 TUs, respectively. The tertiary mixture for the same species produced a TU of 0.86. When exposed to C. dubia, the binary mixtures of NP plus NP1EO and NP plus NP2EO produced 0.48 and 1.12 TUs, respectively, whereas the tertiary mixture gave a TU of 0.90. This research suggests that the compounds are additive or synergistic when present in mixtures.

Infrared spectroscopy of HCOOH in interstellar ice analogues

Context: HCOOH is one of the more common species in interstellar ices with abundances of 1-5% with respect to solid H2O. Aims: This study aims at characterizing the HCOOH spectral features in astrophysically relevant ice mixtures in order to interpret astronomical data. Methods: The ices are grown under high vacuum conditions and spectra are recorded in transmission using a Fourier transform infrared spectrometer. Pure HCOOH ices deposited at 15 K and 145 K are studied, as well as binary and tertiary mixtures containing H2O, CO, CO2 and CH3OH. The mixture concentrations are varied from 50:50% to ~10:90% for HCOOH:H2O. Binary mixtures of HCOOH:X and tertiary mixtures of HCOOH:H2O:X with X = CO, CO2, and CH3OH, are studied for concentrations of ~10:90% and ~7:67:26%, respectively. Results: Pure HCOOH ice spectra show broad bands which split around 120 K due to the conversion of a dimer to a chain-structure. Broad single component bands are found for mixtures with H2O. Additional spectral components are present in mixtures with CO, CO2 and CH3OH. The resulting peak position, full width at half maximum and band strength depend strongly on ice structure, temperature, matrix constituents and the HCOOH concentration. Comparison of the solid HCOOH 5.9, 7.2, and 8.1 micron features with astronomical data toward the low mass source HH 46 and high mass source W 33A shows that spectra of binary mixtures do not reproduce the observed ice features. However, our tertiary mixtures especially with CH3OH match the astronomical data very well. Thus interstellar HCOOH is most likely present in tertiary or more complex mixtures with H2O, CH3OH and potentially also CO or CO2, providing constraints on its formation.

Drop coating deposition Raman spectroscopy of protein mixtures

The technique of drop coating deposition Raman (DCDR) spectroscopy has been shown to be a highly reproducible and sensitive method of obtaining Raman spectra from low concentration protein solutions. This study assesses the ability of DCDR to analyse changes in the relative protein concentrations of aqueous tertiary protein mixtures, with protein levels similar to that found in human tear fluid. The three proteins used to make the mixtures were lysozyme, lactoferrin and albumin. The combination of DCDR spectroscopy and principal components analysis is found to be sensitive enough to detect small changes in the relative protein concentrations, from very small sample volumes (1.5 microl). With certain mixtures it was found that the deposition of proteins was not homogeneous across the width of the ring, but averaging spectra taken at different positions could compensate for this. Principal components regression was able to predict the protein concentrations of test solutions with a good degree of accuracy (root-mean-square errors of prediction of 0.083, 0.112, and 0.082 mg ml(-1) or 8.3, 11.2 and 8.2% of the mean concentration value, for lysozyme, lactoferrin and albumin concentrations respectively). The results of this study suggest that DCDR spectroscopy could be a simple, fast, near-patient technique capable of assisting the diagnosis of ocular infection.

Hepatitis-B Surface Antigen (HBsAg) Powder Formulation: Process and Stability Assessment

The purpose of this study was to develop a hepatitis-B surface antigen (HBsAg) dry powder vaccine formulation suitable for epidermal powder immunization (EPI) via an efficient, scalable powder-formation process. Several HBsAg dry powder formulations were prepared using four different powder-formation methods: freeze-drying/compress/grind/sieve (FD/C/G/S), spray-drying (SD), agarose beads, and spray freeze-drying (SFD). Powder properties and physical stability were determined using particle size analysis, tap density measurement, scanning electron microscopy, optical microscopy, and moisture content analysis. Physical, chemical and biochemical stability of HBsAg was determined by dynamic light scattering, an enzyme immune assay, and immunogenicity in a mouse or hairless guinea pig model. Out of the four powder-formation methods evaluated SFD outperformed other methods in the following considerations: good process efficiency, flexible scalability, and desirable particle characteristics for skin penetration. The stress posed by SFD appeared to be mild as HBsAg in the dry form retained its potency and immunogenicity. Notably, the mechanism of fast freezing by SFD actually promoted the preservation of HBsAg nanoparticle size, in good correlation with long-term biochemical stability. Among several formulations screened, the formulation containing 10 microg HBsAg in 1-mg powder with a tertiary mixture of trehalose, mannitol, and dextran, exhibited excellent overall stability performance. In conclusion, HBsAg dry powder formulations suitable for EPI were successfully prepared using SFD. Further, a systematic formulation development strategy allowed the development and optimization of an HBsAg dry powder formulation, demonstrating excellent long-term physical, biochemical, and immunological stability.

Emissions in combustion of lean methane-air and biomass-air mixtures supported by primary hot burned gas in a multi-stage gas turbine combustor

Thermal reaction of lean to ultra-lean premixed mixtures supported by the hot burned gas from the up-stream stage can be used for obtaining a better trade-off between ultra-low-NO x and high combustion efficiency over a wide range of operations of a gas turbine. A three-stage model combustor designed based on this concept is being developed for a biomass gas-fueled regenerative cycle 10 kW micro-gas turbine. Tubular flame combustion is used for the primary stage and mixtures of lean to ultra-lean compositions are injected into the cross-flowing hot burned gas from the up-stream stage in the secondary and tertiary stages. The emissions and combustion characteristics are evaluated with methane and simulated biomass gas of different CO 2 contents at atmospheric pressure and inlet air temperatures up to 700 K. In the experiments, the fuel flow for the secondary mixture was gradually increased while maintaining the fuel flow to the primary stage in the two-stage combustion mode and the fuel flow for the tertiary mixture was gradually increased while maintaining the fuel flows to the primary and secondary stages in the three-stage combustion mode. The combustor exit NO x concentration corrected to 15% O 2 remained at or slightly lower than the level that was achieved at the start of fuel staging as far as the injected mixture was leaner than the primary mixture and NO x emissions in the 10 ppm level were achieved at gas temperatures less than 1700 K. In contrast, the NO x concentration increase steeply with equivalence ratio in non-staged combustion mode. The reaction of the injected mixture was completion when the reaction zone temperature was higher than 1500 K regardless of inlet air temperature and equivalence ratio of the primary stage. The results show that, the multi-stage combustion where mixtures of ultra-lean to lean compositions are injected into the hot burned gas from the up-stream stage achieved low-NO x emissions and high combustion efficiency over a wide range of overall equivalence ratios or combustor exit gas temperatures. It is found that the CO 2 in the simulated biomass gas suppresses the NO formation by slowing down the progress of combustion reaction, especially at high temperature conditions.

Effects of combinations of Fusarium mycotoxins on the inhibition of macromolecular synthesis, malondialdehyde levels, DNA methylation and fragmentation, and viability in Caco-2 cells

We studied the interactive effects of either binary or tertiary mixtures of Fusarium mycotoxins, deoxynivalenol (DON), zearalenone (ZEA), and fumonisin B1 (FB1) on the human intestinal cell line, Caco-2, using the endpoints including malonedialdehyde (MDA) production, inhibition of protein and DNA syntheses, DNA methylation, DNA fragmentation, and cell viability as measured by the neutral red (NR) test. The mixtures of mycotoxins reduce cellular viability in increasing order: [FB1+ZEA]<[FB1+DON]<[ZEA+DON]<[FB1+DON+ZEA] in NR test. Because FB1 antagonizes the effects of estrogenic Zearalenone, FB1 was assayed against estradiol. In NR assay, mixture of FB1 and estradiol and/or ZEA improves Caco-2 cells viability in contrast to individual effects. Mixtures of ZEA or FB1 and DON, display synergistic effects in lipid peroxidation. The ability of the toxins to inhibit DNA synthesis is 45%, 70%, and 43% for 10 μM of ZEA, DON, and FBI, respectively. Their binary mixtures (at 10 μM each), inhibit DNA synthesis by 35%, 62%, and 65%, far less than additive effects. Surprisingly, the tertiary mixture (10 μM each) only inhibits DNA synthesis by 25%. ZEA, DON, and FB1 induce DNA fragmentation individually. However, mixtures of these mycotoxins always damage DNA to a greater extent. Each individual mycotoxin (10 μM) raises the percentage of 5-methylcytosine ( m 5 dC) in DNA from 4.5% to 9%, while the combination does not increase this rate any further. Altogether, the data indicate that mixtures of Fusarium toxins are able to induce lipid peroxidation, DNA damage, DNA fragmentation, DNA methylation, and cytotoxicity in Caco-2 cells, and suggest a potential promoter effect in human intestinal cells.

Mechanical degradation of filter polymer materials: Polyphenylene sulfide

Polyphenylene sulfide (PPS) is known as a material resistant to high temperature and chemicals; however, there are arguments on the durability of PPS non-woven fabrics to chemicals, such as nitric acid (HNO 3), sulfuric acid (H 2SO 4), and hydrochloric acid (HCl). Therefore, this work aims at investigating the degradation of PPS non-woven fabrics in HNO 3, H 2SO 4 and HCl, and at confirming acid durability of PPS non-woven fabrics. In addition, this paper also studies the interaction among these three acids by measuring the retention of strength in binary or tertiary mixtures of these three acids. A discussion has been made on the acceleration/retardation of PPS degradation by the interactive effects, and also on the chemistry related to the degradation by these acids. Furthermore, there is a linear relationship between the nitric acid concentration and the proportion of carbon in the remaining PPS structures after 100 h of acid exposure. Also, this proportion of carbon is a good indicator of the retained strength in PPS fabrics.

Characterization and Quantitation of a Tertiary Mixture of Salts by Raman Spectroscopy in Simulated Hydrothermal Vent Fluid

This article will demonstrate that Raman spectroscopy can be a useful tool for monitoring the chemical composition of hydrothermal vent fluids in the deep ocean. Hydrothermal vent systems are difficult to study because they are commonly found at depths greater than 1000 m under high pressure (200-300 bar) and venting fluid temperatures are up to 400 degrees C. Our goal in this study was to investigate the use of Raman spectroscopy to characterize and quantitate three Raman-active salts that are among the many chemical building blocks of deep ocean vent chemistry. This paper presents initial sampling and calibration studies as part of a multiphase project to design, develop, and deploy a submersible deep sea Raman instrument for in situ analysis of hydrothermal vent systems. Raman spectra were collected from designed sets of seawater solutions of carbonate, sulfate, and nitrate under different physical conditions of temperature and pressure. The role of multivariate analysis techniques to preprocess the spectral signals and to develop optimal calibration models to accurately estimate the concentrations of a set of mixtures of simulated seawater are discussed. The effects that the high-pressure and high-temperature environment have upon the Raman spectra of the analytes were also systematically studied. Information gained from these lab experiments is being used to determine design criteria and performance attributes for a deployable deep sea Raman instrument to study hydrothermal vent systems in situ.