Determination of picogram levels of midazolam, and 1- and 4-hydroxymidazolam in human plasma by gas chromatography-negative chemical ionization-mass spectrometry.

Midazolam is a widely accepted probe for phenotyping cytochrome P4503A. A gas chromatography-mass spectrometry (GC-MS)-negative chemical ionization method is presented which allows measuring very low levels of midazolam (MID), 1-OH midazolam (1OHMID) and 4-OH midazolam (4OHMID), in plasma, after derivatization with the reagent N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide. The standard curves were linear over a working range of 20 pg/ml to 5 ng/ml for the three compounds, with the mean coefficients of correlation of the calibration curves (n = 6) being 0.999 for MID and 1OHMID, and 1.0 for 4OHMID. The mean recoveries measured at 100 pg/ml, 500 pg/ml, and 2 ng/ml, ranged from 76 to 87% for MID, from 76 to 99% for 1OHMID, from 68 to 84% for 4OHMID, and from 82 to 109% for N-ethyloxazepam (internal standard). Intra- (n = 7) and inter-day (n = 8) coefficients of variation determined at three concentrations ranged from 1 to 8% for MID, from 2 to 13% for 1OHMID and from 1 to 14% for 4OHMID. The percent theoretical concentrations (accuracy) were within +/-8% for MID and 1OHMID, within +/-9% for 4OHMID at 500 pg/ml and 2 ng/ml, and within +/-28% for 4OHMID at 100 pg/ml. The limits of quantitation were found to be 10 pg/ml for the three compounds. This method can be used for phenotyping cytochrome P4503A in humans following the administration of a very low oral dose of midazolam (75 microg), without central nervous system side-effects.

Dewaterability of sewage sludge by ultrasonic, thermal and chemical treatments

Sludges resulting from wastewater treatment processes have a characteristically high water content, which complicates handling operations such as pumping, transport and disposal. To enhance the dewatering of secondary sludge, the effect of ultrasound waves, thermal treatment and chemical conditioning with NaOH have been studied. Two features of treated sludges were examined: their rheological behavior and their dewaterability. The rheological tests consisted of recording shear stress when the shear rate increases and decreases continuously and linearly with time, and when it increases and decreases in steps. Steady-state viscosity and thixotropy were obtained from the rheological tests, and both decreased significantly in all cases with increased treatment intensity. Centrifugation of ultrasonicated and thermally treated sludges allowed the total solid content to be increased by approximately 16.2% and 17.6%, respectively. These dewatered sludges had a lower viscosity and thixotropy than the untreated sludge. In contrast, alkali conditioning barely allowed the sludge to be dewatered by centrifugation, despite decreasing its viscosity and thixotropy.

Atomic diversity, molecular diversity, and chemical diversity: the concept of chemodiversity.

This minireview is meant as an introduction to the following paper. To this end, it presents the general background against which the joint paper should be understood. The first objective of the present paper is thus to clarify some concepts and related terminology, drawing a clear distinction between i) atomic diversity (i.e., atomic-property space), ii) molecular or macromolecular diversity (i.e., molecular- or macromolecular-property spaces), and iii) chemical diversity (i.e., chemical-diversity space). The first refers to the various electronic states an atom can occupy. The second encompasses the conformational and property spaces of a given (macro)molecule. The third pertains to the diversity in structure and properties exhibited by a library or a supramolecular assembly of different chemical compounds. The ground is thus laid for the content of the joint paper, which pertains to case ii, to be placed in its broader chemodiversity context. The second objective of this paper is to point to the concepts of chemodiversity and biodiversity as forming a continuum. Chemodiversity is indeed the material substratum of organisms. In other words, chemodiversity is the material condition for life to emerge and exist. Increasing our knowledge of chemodiversity is thus a condition for a better understanding of life as a process.

7Ni-O chemical interaction and the transition temperature of Ni-doped Bi2Sr2Ca1Cu2O8

We find that even very low Ni doping levels of high-quality Bi2Sr2Ca1Cu2O8 single crystals strongly affect the transition temperature T(c). We also observed that T(c) is not related to the total Ni concentration, but only to that of Ni engaged in NiO-type bonds. By controlling the temperature during crystal growth, one can modify the relative weight of Ni in NiO-type bonds with respect to other configurations-and therefore T(c).

Differentiated chemical reactivity of nanoparticles toward DTT

RATIONALE: Induction of oxidative stress and impairment of the antioxidant defense are considered important biological responses following nanoparticle (NP) exposure. The acellular in vitro dithiothreitol (DTT) assay is proposed to measure the oxidative potential of NP. In addition, DTT can be considered as a model compound of sulfur containing antioxidants. The objective of this work is to evaluate the surface reactivity in solution of a NP panel toward DTT. METHOD: The NP panel was composed of four carbonaceous particles, six types of metal oxides and silver with primary size ranged from 7 to 300 nm. Suspensions were prepared in surfactant solution with 30 min sonication. DTT was used as reductant to evaluate the oxidative properties of the different NP. The determination of the NP ability to catalyze electron transfer from DTT to oxygen was carried out as described in Sauvain et al., Nanotoxicology, 2008, 2:3, 121−129. RESULTS: All the carbonaceous NP catalyzed the oxidation of DTT by oxygen following the mass based order: carbon black > diesel exhaust particle > nanotubes > fullerene. A contrasting reactivity was observed for the metallic NP. Except for nickel oxide and metallic silver, which reacted similarly to the carbonaceous NP, all other metal oxides hindered the oxidation of DTT by oxygen, with ZnO being the most effective one. CONCLUSIONS : DTT was stabilized against oxidation in the presence of metal oxide NP in the solution. This suggests that different chemical interactions take place compared with carbonaceous NP. To explain these differences, we hypothesize that DTT could form complexes with the metal oxide surface (or dissolved metal ions), rendering it less susceptible to oxidation. By analogy, such a process could be thought to apply in biological systems with sulfur−containing antioxidants, reducing their buffer capacity. Such NP could thus contribute to oxidative stress by an alternative mechanism.

Evaluation of the Chemical Durability of Iowa Fly Ash Concretes, HR-327, 1993

The major objective of this research project was to investigate how Iowa fly ashes influenced the chemical durability of portland cement based materials. Chemical durability has become an area of uncertainty because of the winter application of deicer salts (rock salts) that contain a significant amount of sulfate impurities. The sulfate durability testing program consisted of monitoring portland cement-fly ash paste, mortar and concrete test specimens that had been subjected to aqueous solutions containing various concentrations of salts (both sulfate and chloride). The paste and mortar specimens were monitored for length as a function of time. The concrete test specimens were monitored for length, relative dynamic modulus and mass as a function of time. The alkali-aggregate reactivity testing program consisted of monitoring the expansion of ASTM C311 mortar bar specimens that contained three different aggregates (Pyrex glass, Oreapolis and standard Ottawa sand). The results of the sulfate durability study indicated that the paste and concrete test specimens tended to exhibit surface spalling but only very slow expansive tendencies. This suggested that the permeability of the test specimens was controlling the rate of deterioration. Concrete specimens are still being monitored because the majority of the test specimens have expanded less than 0.05%; hence, this makes it difficult to estimate the service life of the concrete test specimens or to quantify the performance of the different fly ashes that were used in the study. The results of the mortar bar studies indicated that the chemical composition of the various fly ashes did have an influence on their sulfate resistance. Typically, Clinton and Louisa fly ashes performed the best, followed by the Ottumwa, Neal 4 and then Council Bluffs fly ashes. Council Bluffs fly ash was the only fly ash that consistently reduced the sulfate resistance of the many different mortar specimens that were investigated during this study. None of the trends that were observed in the mortar bar studies have yet become evident in the concrete phase of this project. The results of the alkali-aggregate study indicated that the Oreapolis aggregate is not very sensitive to alkali attack. Two of the fly ashes, Council Bluffs and Ottumwa, tended to increase the expansion of mortar bar specimens that contained the Oreapolis aggregate. However, it was not clear if the additional expansion was due to the alkali content of the fly ash, the periclase content of the fly ash or the cristobalite content of the fly ash, since all three of these factors have been found to influence the test results.

Effects of long-term irrigation with treated wastewater. Part I: Evolution of soil physico-chemical properties

The long-term impact of irrigation on a Mediterranean sandy soil irrigated with Treated wastewater (TWW) since 1980 was evaluated. The main soil properties (CEC, pH, size distribution, exchangeable cations and chloride, hydraulic conductivity) as well as the organic matter and Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated control soil at various soil depths were monitored and compared during a 2 years experiment. In this first part, the evolution of the physico-chemical soil properties was described. The irrigation with TWW was beneficial with regard to water and nutrient supplying. All the exchangeable cations other than K(+) were higher in the irrigated soil than in the reference one. A part of the exchangeable cations was not fixed on the exchange complex but stored as labile salts or in concentrated soil solution. Despite the very sandy soil texture, both saturated and unsaturated hydraulic conductivity exhibited a significant diminution in the irrigated soil, but remained high enough to allow water percolation during rainy periods and subsequent leaching of accumulated salts, preventing soil salinization. In the irrigated soil, exchangeable sodium percentage (ESP) exhibited high values (20% on average) and the soil organic C was lower than in the reference. No significant effect was noticed on soil mineralogical composition due to irrigation. (C) 2010 Published by Elsevier Ltd.

Characteristics of Chemical Treated Roadway Surfaces, HR-33, 1963

Iowa Highway Commission Project HR-33, "Characteristics of Chemically Treated Roadway Surfaces", was investigated at the Iowa Engineering Experiment Station under Project 375-S. The purpose of the project as originally proposed was to study the physical and chemical characteristics of chemically treated roadway surfaces. All chemical treatments were to be included, but only sodium chloride and calcium chloride treated roadways were investigated. The uses of other types of chemical treatment were not discovered until recently, notably spent sulfite liquor and a commercial additive. Costs of stabilized secondary roads in Hamilton County averaged $4300.00 per mile even though remanent soil-aggregate material was used. The cost of similar roads in Franklin County was $4400.00 per mile. The Franklin County road surfaces were constructed entirely from materials that were hauled to the road site. Costs in Butler County were a little over $3000.00 per mile some eight years ago. Chemical investigations indicate that calcium chloride and sodium chloride are lost through leaching. Approximately 95 percent of the sodium chloride appears to have been lost, and nearly 65 percent of the calcium chloride has disappeared. The latter value may be much in error since surface dressings of calcium chloride are commonly used and have not been taken into account. Clay contents of the soil-aggregate-chemical stabilized roads range from about 6 to ll percent, averaging 8 or 9 percent. The thicknesses of stabilized mats are usually 2 to 4 inches, with in-place densities ranging from 130 to 145 pcf. Generally the densities found in sodium chloride stabilized roads were slightly higher than those found in the calcium chloride stabilized roads.

Effects of soil management systems on soil microbial activity, bulk density and chemical properties

The objective of this experiment was to study the effects of soil management systems on the bulk density, chemical soil properties, and on the soil microbial activity on a Latossolo Vermelho distrófico (Oxisol). Soil samples were collected from plots under the following management conditions: a) natural dense "cerrado" vegetation (savanna); b) degraded Brachiaria decumbens pasture, 20 years old; c) no-tillage treatment with annual crop sequence (bean, corn, soybean and dark-oat in continuous rotation), 8 years old; d) conventional tillage treatment with crop residues added to the soil, and annual crop sequence, 10 years old. The continuous use of no-tillage system resulted in an increase in microbial biomass and decrease in soil basal respiration, therefore displaying evident long-term effects on the increase of soil C content. The no-tillage system also provided an improvement in bulk density and chemical properties of the soil. Hence, the no-tillage management system could be an alternative for the conservation and maintenance of physical and chemical conditions and the productive potential of "cerrado" soils.

Handbook of instrumental techniques for materials, chemical and biosciences research

This Handbook contains a collection of articles describing instrumental techniques used for Materials, Chemical and Biosciences research that are available at the Scientific and Technological Centers of theUniversity of Barcelona (CCiTUB). The CCiTUB are a group of facilities of the UB that provide both the research community and industry with ready access to a wide range of major instrumentation.Together with the latest equipment and technology, the CCiTUB provide expertise in addressing the methodological research needs of the user community and they also collaborate in R+D+i Projectswith industry. CCiTUB specialists include technical and Ph.D.-level professional staff members who are actively engaged in methodological research. Detailed information on the centers’ resources andactivities can be found at the CCiTUB website www.ccit.ub.edu ...

Physical and chemical characteristics of sapota fruit at different stages of maturation

In the present work, the physical and chemical characteristics in three stages of maturation of sapota (Manilkara zapota L.P. Royen) fruit were studied as well as its post-harvest behavior during storage at ambient and refrigerated conditions. With the advance of maturation, the concentration of the reducing sugars increased while the total acidity and tannin contents decreased. The fruits which did not have their pedicel removed during the post-harvest presented the storage time superior when compared with the fruits having their pedicels removed. The fruits stored under refrigeration had higher weight retention as compared to the fruits stored under ambient conditions.

Biological monitoring of chemical exposure : toxicokinetic differences due to age and sex

Human biomonitoring is a widely used method in the assessment of occupational exposure to chemical substances and recommended biological limits are published periodically for interpretation and decision-making. However, it is increasingly recognized that a large variability is associated with biological monitoring, making interpretation less efficient than assumed. In order to improve the applicability of biological monitoring, specific factors responsible for this variability should be identified and their contribution quantified. Among these factors, age and sex are easily identifiable, and present knowledge about pharmaceutical chemicals suggests that they play an important role on the toxicokinetics of occupational chemical agents, and therefore on the biological monitoring results.The aim of the present research project was to assess the influence of age and sex on biological indicators corresponding to organic solvents. This has been done experimentally and by toxicokinetic computer simulation. Another purpose was to explore the effect of selected CYP2E1 polymorphisms on the toxicokinetic profile.Age differences were identified by numerical simulations using a general toxicokinetic model from a previous study which was applied to 14 chemicals, representing 21 specific biological entities, with, among others, toluene, phenol, lead and mercury. These models were runn with the modified parameters, indicating in some cases important differences due to age. The expected changes are mostly of the order of 10-20 %, but differences up to 50 % were observed in some cases. These differences appear to depend on the chemical and on the biological entity considered.Sex differences were quantified by controlled human exposures, which were carried out in a 12 m3 exposure chamber for three organic solvents separately: methyl ethyl ketone, 1-methoxy-2-propanol and 1,1,1-trichloroethane. The human volunteer groups were composed 12 of ten young men and fifteen young women, the latter subdivided into those with and without hormonal contraceptive. They were exposed during six hours at rest and at half of the threshold limit value. The kinetics of the parent compounds (organic volatiles) and their metabolite(s) were followed in blood, urine and expired air over time. Analyses of the solvent and their metabolites were performed by using headspace gas chromatography, CYP2E1 genotypes by using PCR-based RFLP methods. Experimental data were used to calibrate the toxicokinetic models developed for the three solvents. The results obtained for the different biomarkers of exposure mainly showed an effect on the urinary levels of several biomarkers among women due to the use of hormonal contraceptive, with an increase of about 50 % in the metabolism rate. The results also showed a difference due to the genotype CYP2E1*6, when exposed to methyl ethyl ketone, with a tendency to increase CYP2E1 activity when volunteers were carriers of the mutant allele. Simulations showed that it is possible to use simple toxicokinetic tools in order to predict internal exposure when exposed to organic solvents. Our study suggests that not only physiological differences but also exogenous sex hormones could influence CYP2E1 enzyme activity. The variability among the urinary biological indicators levels gives evidence of an interindividual susceptibility, an aspect that should have its place in the approaches for setting limits of occupational exposure.

Chemical nature of soil humified fractions and their bioactivity

The aim of this work was to evaluate the humus composition from an Ultisol from Campos dos Goytacazes, RJ, Brazil. Soil samples of four depths (0-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 m) and its chemical nature were analysed by elemental composition, E4/E6 ratios and Fourier transformed infrared spectroscopy. The bioactivity of these humified substances was evaluated through their action on maize root growth and H+-ATPase activity of roots microsomes. In topsoil, the content of high condensed alkaline soluble humic substances is greater than that found in the subsuperficial layers. The chemical nature of humic and fulvic acids also varied with the soil depth. The humic acids isolated from the soil samples exhibited higher bioactivity compared with the fulvic acids. Moreover, the results suggest that more condensed humic substances can promote highest stimulation of the microsomal H+-ATPases from maize roots. These data reinforce the concept that the activity of the H+ pumps can be used as a biochemical marker for evaluation of humic substances bioactivity.

Chemical probes that differentially modulate peroxisome proliferator-activated receptor alpha and BLTR, nuclear and cell surface receptors for leukotriene B(4).

Peroxisome proliferator-activated receptor alpha (PPARalpha)is a nuclear receptor for various fatty acids, eicosanoids, and hypolipidemic drugs. In the presence of ligand, this transcription factor increases expression of target genes that are primarily associated with lipid homeostasis. We have previously reported PPARalpha as a nuclear receptor of the inflammatory mediator leukotriene B(4) (LTB(4)) and demonstrated an anti-inflammatory function for PPARalpha in vivo (Devchand, P. R., Keller, H., Peters, J. M., Vazquez, M., Gonzalez, F. J., and Wahli, W. (1996) Nature 384, 39-43). LTB(4) also has a cell surface receptor (BLTR) that mediates proinflammatory events, such as chemotaxis and chemokinesis (Yokomizo, T., Izumi, T., Chang, K., Takuwa, Y., and Shimizu, T. (1997) Nature 387, 620-624). In this study, we report on chemical probes that differentially modulate activity of these two LTB(4) receptors. The compounds selected were originally characterized as synthetic BLTR effectors, both agonists and antagonists. Here, we evaluate the compounds as effectors of the three PPAR isotypes (alpha, beta, and gamma) by transient transfection assays and also determine whether the compounds are ligands for these nuclear receptors by coactivator-dependent receptor ligand interaction assay, a semifunctional in vitro assay. Because the compounds are PPARalpha selective, we further analyze their potency in a biological assay for the PPARalpha-mediated activity of lipid accumulation. These chemical probes will prove invaluable in dissecting processes that involve nuclear and cell surface LTB(4) receptors and also aid in drug discovery programs.