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This study aims to assess the potential association of MBL2 gene single nucleotide polymorphisms (SNPs) to Chlamydia trachomatis infection. We analysed a selected sample of 492 DNA and serum specimens from Dutch Caucasian women. Women were categorized into four groups of infection status based on the results of DNA and antibody tests for C. trachomatis: Ct-DNA+/IgG+, Ct-DNA+/IgG−, Ct-DNA−/IgG+, and Ct-DNA−/IgG−. We compared six MBL2 SNPs (−619G > C (H/L), −290G > C (Y/X), −66C > T (P/Q), +154C > T (A/D), +161A > G (A/B), and +170A > G (A/C)) and their respective haplotypes in relation to these different subgroups. The −619C (L) allele was less present within the Ct-DNA−/IgG+ group compared with the Ct-DNA−/IgG− group (OR = 0.49; 95% CI: 0.28–0.83), while the +170G (C) allele was observed more in the Ct-DNA+/IgG+ group as compared with the Ct-DNA−/IgG− group (OR = 2.4; 95% CI: 1.1–5.4). The HYA/HYA haplotype was more often present in the Ct-DNA−/IgG− group compared with the Ct-DNA+/IgG+ group (OR = 0.37; 95% CI: 0.16–0.87). The +170G (C) allele was associated with increased IgG production (p = 0.048) in C. trachomatis PCR-positive women. This study shows associations for MBL in immune reactions to C. trachomatis. We showed clear associations between MBL2 genotypes, haplotypes, and individuals’ stages of C. trachomatis DNA and IgG positivity.

Background: The mechanisms underlying dysfunction in the sinoatrial node (SAN), the heart’s primary pacemaker, are incompletely understood. Electrical and Ca2+-handling remodeling have been implicated in SAN dysfunction associated with heart failure, aging, and diabetes. Cardiomyocyte [Na+]i is also elevated in these diseases, where it contributes to arrhythmogenesis. Here, we sought to investigate the largely unexplored role of Na+ homeostasis in SAN pacemaking and test whether [Na+]i dysregulation may contribute to SAN dysfunction. Methods: We developed a dataset-specific computational model of the murine SAN myocyte and simulated alterations in the major processes of Na+ entry (Na+/Ca2+ exchanger, NCX) and removal (Na+/K+ ATPase, NKA). Results: We found that changes in intracellular Na+ homeostatic processes dynamically regulate SAN electrophysiology. Mild reductions in NKA and NCX function increase myocyte firing rate, whereas a stronger reduction causes bursting activity and loss of automaticity. These pathologic phenotypes mimic those observed experimentally in NCX- and ankyrin-B-deficient mice due to altered feedback between the Ca2+ and membrane potential clocks underlying SAN firing. Conclusions: Our study generates new testable predictions and insight linking Na+ homeostasis to Ca2+ handling and membrane potential dynamics in SAN myocytes that may advance our understanding of SAN (dys)function.

The effect of initial water activity of MTBE (methyl tert-butyl ether) medium on CALB (Candida antarctica lipase B) catalyzed esterification reaction is investigated using experimental methods and classical molecular dynamics (MD) simulations. The experimental kinetic studies show that the initial reaction rate of CALB-catalyzed esterification reaction between butyric acid and ethanol decreases with increasing initial water activity of the medium. The highest rate of esterification is observed at the lowest water activity studied. MD simulations were performed to gain a molecular insight on the effect of initial water activity on the rate of CALB-catalyzed reaction. Our results show that hydration has an insignificant effect on the structure and flexibility of CALB. Rather, it appears that water molecules bind to certain regions (“hot spots”) on the CALB surface and form clusters. The size of the water clusters at these hot spot regions gradually increase and expand with increasing water activity. Consequently, the surface area of CALB covered by the water molecules also increases. Specifically, our results indicate that a particular water cluster located close to the active site partially cover the binding pocket of substrate at high water activity. As a consequence, the effective concentration of substrate at the catalytic site decreases. Therefore, the reaction rate slows down with increasing water activity, which correlates well with the observed decrease in the experimentally determined initial reaction rate.

Complexes featuring metal–silicon bonds play a key role in many catalytic and stoichiometric transformations. As such, it is important to understand the underlying electronic structures of such units and the reactivity patterns they engender, which in many cases differ substantially from well-known patterns for metal–carbon bonds. This review seeks to provide a framework for understanding reactivity of metal/organosilicon units, focusing specifically on considerations for catalysis, similarities and differences between M–C and M–Si chemistry, and possibilities for M/Si cooperative catalysis. [ABSTRACT FROM AUTHOR]

We review different approaches to description, classification, and understanding of intermetallic structures of any complexity. All these approaches are based on the representation of the intermetallic structure as a periodic graph (net). A special attention is paid to the nanocluster model, which enables one to separate structural units and to describe their assemblage in intermetallics with strict computer algorithms. We demonstrate the abilities of the model with analysis of 12,315 intermetallic structures from the Inorganic Crystal Structure Database. [ABSTRACT FROM AUTHOR]

Trees have multi-aspect influence on the microclimate in urbanised areas. Therefore, it is important to investigate the biotic and abiotic factors affecting their health. The aim of the conducted study was to assess the chemical composition of soils and the nutritional status of lime and horse chestnut trees in selected sites and the influence of these factors on the condition and health of these tree species in urbanised areas. The research was conducted on selected trees (n = 643) growing in different parts of the city. The soils and plants were analysed for the content of macro- and microelements, sodium and heavy metals. A canonical variation analysis (CVA)–the canonical variant of Fisher's linear discriminant analysis (LDA) was used to construct the model. The CVA enabled the creation of 4 CCA models. The research showed that in general, the soil in all the sites of lime and horse chestnut trees was alkalised–at the same time it was characterised by low salinity. Despite the alkaline soil the statistical analysis showed a positive correlation between the content of manganese in the lime leaves and the deterioration of their health. In spite of that due to the satisfactory health status and condition of trees in most locations temporary guide values of nutrients were proposed for trees growing in urbanised areas. The following temporary guide values of nutrients were proposed for the horse chestnut trees (% d. m.): N 2.38%-4.71%, P 0.24%-0.46%, K 1.13%-2.31%, Ca 1.05%-2.12%, Mg 0.16%-0.42%, S 0.12%-0.23%; Fe 89.8–198.8, Zn 17.6–33.1, Cu 7.36–19.61 (mg kg-1 d. m.). The following temporary guide values were proposed for the small-leaved lime-trees (% d. m.): N 2.45%-3.22%, P 0.27%-0.42%, K 1.52%-2.86%, Ca 1.43%-2.02%, Mg 0.19%-0.35%, S 0.19%-0.25%; Fe 137.6–174.3, Zn 20.2–23.8, Cu 8.36–9.79 (mg kg-1 d. m.). [ABSTRACT FROM AUTHOR]

Background: Use of hormonal contraceptives has been associated with Staphylococcus aureus nasal carriage in adult women. However, the role of hormonal contraceptives in S. aureus colonization among adolescents and associations with progestin only contraceptives are unknown. Methods: We obtained nasal and throat swab samples from 439 girls aged 17–21 years in the population-based Tromsø study Fit Futures, 2012–2013, Norway, with information on lifestyle, health and biomarkers. We used multivariable logistic regression to study the association between use of hormonal contraceptives and Staphylococcus aureus carriage while adjusting for potential confounding factors. Results: Staphylococcus aureus nasal carriage prevalence were 34%, 42%, and 61% among progestin-only users, non-users, and progestin-estrogen combination contraceptive users, respectively (P<0.001). Use of combination contraceptives doubled the odds of nasal carriage (non-users reference; OR = 2.31, 95%CI = 1.43–3.74). The OR of nasal carriage was 0.29 among progestin-only users compared to combination contraceptives users (95% CI = 0.12–0.67). Discussion: In this study, use of combination hormonal contraceptives was associated with higher risk of Staphylococcus aureus nasal carriage in adolescent girls. Experimental design studies are needed to establish the role of exogenous sex steroids in Staphylococcus aureus colonization in women. [ABSTRACT FROM AUTHOR]

Background: The population of stallion spermatozoa that survive thawing experience compromised mitochondrial functionality and accelerated senescence, among other changes. It is known that stallion spermatozoa show very active oxidative phosphorylation that may accelerate sperm senescence through increased production of reactive oxygen species. Rosiglitazone has been proven to enhance the glycolytic capability of stallion spermatozoa maintained at ambient temperature. Objectives: Thus, we hypothesized that thawed sperm may also benefit from rosiglitazone supplementation. Materials and methods: Thawed sperm were washed and resuspended in Tyrodes media, and the samples were divided and supplemented with 0 or 75 μM rosiglitazone. After one and two hours of incubation, mitochondrial functionality, Akt phosphorylation and caspase 3 activity were evaluated. Additional samples were incubated in the presence of an Akt1/2 inhibitor, compound C (an AMPK inhibitor) or GW9662 (an antagonist of the PPARγ receptor). Results: Rosiglitazone maintained Akt phosphorylation and reduced caspase 3 activation (p<0.01), both of which were prevented by incubation in the presence of the three inhibitors. Rosiglitazone also enhanced mitochondrial functionality (P<0.01). Conclusion: We provide the first evidence that the functionality of frozen stallion spermatozoa can be potentially improved after thawing through the activation of pro survival pathways, providing new clues for improving current sperm biotechnology. [ABSTRACT FROM AUTHOR]

Bcl-2 family proteins control a decisive apoptotic event: mitochondrial outer membrane permeabilization (MOMP). To discover MOMP-regulating proteins, we expressed a library of intracellular single-chain variable fragments (scFvs) (“intrabodies”) and selected for those rescuing cells from apoptosis induced by BimS (the short isoform of Bim). One anti-apoptotic intrabody, intrabody 5 (IB5), recognized pyruvate kinase M2 (PKM2), which is expressed in cancer cells. PKM2 deletion ablated this clonogenic rescue; thus, IB5 activated a latent cytoprotective function of PKM2. This resulted not from pyruvate kinase activity per se but rather from the formation of an active tetrameric conformation of PKM2. A stably tetrameric PKM2 mutant, K422R, promoted cell survival even in the absence of IB5, and IB5 further increased survival. Mitochondria isolated from IB5-expressing cells were relatively resistant to MOMP in vitro. In cells, IB5 expression up-regulated Mitofusin-1 (Mfn1) and increased mitochondrial length. Importantly, Mfn1 deficiency abrogated IB5’s cytoprotective effect. PKM2’s anti-apoptotic function could help explain its preferential expression in human cancer. [ABSTRACT FROM AUTHOR]

Extraction and quantification of nano- and microplastics from sediments and soils is challenging. Although no standard method has been established so far, flotation is commonly used to separate plastic from mineral material. The objective of this study was to test the efficiency of flotation for the extraction of nano- and microplastics from biosolids and soil. We spiked biosolids and soil samples with polystyrene nano- and microbeads (0.05, 1.0, 2.6, 4.8, and 100 μm diameter). Different extraction methods (w/ and w/o H2O2 digestion) were tested, and plastic beads were separated from mineral particles by flotation in a ZnCl2 solution. Plastic particles were quantified by UV-Vis spectrometry and gravimetrically. While large beads (100 μm) could be quantitatively extracted (∼100%) from both biosolids and soils, smaller beads had low extraction efficiencies (ranging from 5 to 80%, with an average of 20%). Except for the 100 μm beads, oxidation with H2O2 negatively impacted the extraction efficiencies. For the soil, extraction with water only, followed by flotation in a ZnCl2 solution, resulted in relatively high extraction efficiencies (>75%) for beads larger than 1 μm, but low efficiencies (<30%) for the 0.05 and 1.0 μm beads. Our results indicate that while flotation generally works to separate plastic nano- and microbeads in a solution, the challenge is to quantitatively extract nano- and microbeads from a biosolids or soil matrix. Samples high in organic matter content require removal of the organic matter, but the common method of H2O2 oxidation leads to poor extraction efficiencies for nano- and microbeads. [ABSTRACT FROM AUTHOR]

Invasive fungal infections caused by the pathogen Candida albicans have transitioned from a rare curiosity to a major cause of human mortality. This is in part due to the emergence of resistance to the limited number of antifungals available to treat fungal infections. Azoles function by targeting the biosynthesis of ergosterol, a key component of the fungal cell membrane. Loss-of-function mutations in the ergosterol biosynthetic gene ERG3 mitigate azole toxicity and enable resistance that depends upon fungal stress responses. Here, we performed a genome-wide synthetic genetic array screen in Saccharomyces cerevisiae to map ERG3 genetic interactors and uncover novel circuitry important for azole resistance. We identified nine genes that enabled erg3-mediated azole resistance in the model yeast and found that only two of these genes had a conserved impact on resistance in C. albicans. Further, we screened a C. albicans homozygous deletion mutant library and identified 13 genes for which deletion enhances azole susceptibility. Two of the genes, RGD1 and PEP8, were also important for azole resistance acquired by diverse mechanisms. We discovered that loss of function of retrograde transport protein Pep8 overwhelms the functional capacity of the stress response regulator calcineurin, thereby abrogating azole resistance. To identify the mechanism through which the GTPase activator protein Rgd1 enables azole resistance, we selected for mutations that restore resistance in strains lacking Rgd1. Whole genome sequencing uncovered parallel adaptive mechanisms involving amplification of both chromosome 7 and a large segment of chromosome 3. Overexpression of a transporter gene on the right portion of chromosome 3, NPR2, was sufficient to enable azole resistance in the absence of Rgd1. Thus, we establish a novel mechanism of adaptation to drug-induced stress, define genetic circuitry underpinning azole resistance, and illustrate divergence in resistance circuitry over evolutionary time. [ABSTRACT FROM AUTHOR]

Bacterial morphology is a complex trait that is highly sensitive to changes in the environment. For heterotrophic organisms, such as Escherichia coli, increases in nutrient levels are frequently accompanied by several-fold increases in both size and growth rate. Despite the dramatic nature of these changes, how alterations in nutrient availability translate into changes in growth and morphology remains a largely open question. To understand the signaling networks coupling nutrient availability with size and shape, we examined the impact of deletions in the entirety of non-essential central carbon metabolic genes on E. coli growth rate and cell size. Our data reveal the presence of multiple metabolic nodes that play important yet distinctive roles in dictating biosynthetic capacity and shaping cell morphology. Specifically, perturbations of acetyl-CoA metabolism impact cell size and division through changes in fatty acid synthesis. Additionally, we identify a genetic pathway linking glucose levels to cell width through the signaling molecule cyclic-AMP. Together our findings highlight a surprising diversity of factors and mechanisms contributing to growth potential and cell morphology, providing a foundation for further studies. [ABSTRACT FROM AUTHOR]

Background: Vitamin D deficiency may increase esophageal cancer risk. Vitamin D affects genes regulating proliferation, apoptosis, and differentiation and induces the tumor suppressor 15-hydroxyprostaglandin dehydrogenase (PGDH) in other cancers. This nonrandomized interventional study assessed effects of vitamin D supplementation in Barrett’s esophagus (BE). We hypothesized that vitamin D supplementation may have beneficial effects on gene expression including 15-PGDH in BE. Methods: BE subjects with low grade or no dysplasia received vitamin D3 (cholecalciferol) 50,000 international units weekly plus a proton pump inhibitor for 12 weeks. Esophageal biopsies from normal plus metaplastic BE epithelium and blood samples were obtained before and after vitamin D supplementation. Serum 25-hydroxyvitamin D was measured to characterize vitamin D status. Esophageal gene expression was assessed using microarrays. Results: 18 study subjects were evaluated. The baseline mean serum 25-hydroxyvitamin D level was 27 ng/mL (normal ≥30 ng/mL). After vitamin D supplementation, 25-hydroxyvitamin D levels rose significantly (median increase of 31.6 ng/mL, p<0.001). There were no significant changes in gene expression from esophageal squamous or Barrett’s epithelium including 15-PGDH after supplementation. Conclusion: BE subjects were vitamin D insufficient. Despite improved vitamin D status with supplementation, no significant alterations in gene expression profiles were noted. If vitamin D supplementation benefits BE, a longer duration or higher dose of supplementation may be needed. [ABSTRACT FROM AUTHOR]

The pro-apoptotic BCL2 gene family member, BAX, plays a pivotal role in the intrinsic apoptotic pathway. Under cellular stress, BAX recruitment to the mitochondria occurs when activated BAX forms dimers, then oligomers, to initiate mitochondria outer membrane permeabilization (MOMP), a process critical for apoptotic progression. The activation and recruitment of BAX to form oligomers has been studied for two decades using fusion proteins with a fluorescent reporter attached in-frame to the BAX N-terminus. We applied high-speed live cell imaging to monitor the recruitment of BAX fusion proteins in dying cells. Data from time-lapse imaging was validated against the activity of endogenous BAX in cells, and analyzed using sigmoid mathematical functions to obtain detail of the kinetic parameters of the recruitment process at individual mitochondrial foci. BAX fusion proteins behave like endogenous BAX during apoptosis. Kinetic studies show that fusion protein recruitment is also minimally affected in cells lacking endogenous BAK or BAX genes, but that the kinetics are moderately, but significantly, different with different fluorescent tags in the fusion constructs. In experiments testing BAX recruitment in 3 different cell lines, our results show that regardless of cell type, once activated, BAX recruitment initiates simultaneously within a cell, but exhibits varying rates of recruitment at individual mitochondrial foci. Very early during BAX recruitment, pro-apoptotic molecules are released in the process of MOMP, but different molecules are released at different times and rates relative to the time of BAX recruitment initiation. These results provide a method for BAX kinetic analysis in living cells and yield greater detail of multiple characteristics of BAX-induced MOMP in living cells that were initially observed in cell free studies. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a pathogen and a commensal bacterial species that is found in humans. Bacterial two-component systems (TCSs) sense and respond to environmental stresses, which include antimicrobial agents produced by other bacteria. In this study, we analyzed the relation between the TCS SrrAB and susceptibility to the hydrogen peroxide (H2O2) that is produced by Streptococcus sanguinis, which is a commensal oral streptococcus. An srrA-inactivated S. aureus mutant demonstrated low susceptibility to the H2O2 produced by S. sanguinis. We investigated the expression of anti-oxidant factors in the mutant. The expression of katA in the mutant was significantly higher than in the wild-type (WT) in the presence or absence of 0.4 mM H2O2. The expression of dps in the mutant was significantly increased compared with the WT in the presence of H2O2 but not in the absence of H2O2. A katA or a dps-inactivated mutant had high susceptibility to H2O2 compared with WT. In addition, we found that the nitric oxide detoxification protein (flavohemoglobin: Hmp), which is regulated by SrrAB, was related to H2O2 susceptibility. The hmp-inactivated mutant had slightly lower susceptibility to the H2O2 produced by S. sanguinis than did WT. When a srrA-inactivated mutant or the WT were co-cultured with S. sanguinis, the population percentage of the mutant was significantly higher than the WT. In conclusion, SrrAB regulates katA, dps and hmp expression and affects H2O2 susceptibility. Our findings suggest that SrrAB is related in vivo to the co-existence of S. aureus with S. sanguinis. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is an opportunistic pathogen responsible for a high proportion of nosocomial infections. This study was conducted to assess the bacterial responses in the cytoplasmic composition of amino acids and ribosomal proteins under various environmental conditions designed to mimic those on the human skin or within a wound site: pH6-8, temperature 35–37°C, and additional 0–5% NaCl. It was found that each set of environmental conditions elicited substantial adjustments in cytoplasmic levels of glutamic acid, aspartic acid, proline, alanine and glycine (P< 0.05). These alterations generated characteristic amino acid profiles assessed by principle component analysis (PCA). Substantial alterations in cytoplasmic amino acid and protein composition occurred during growth under conditions of higher salinity stress implemented via additional levels of NaCl in the growth medium. The cells responded to additional NaCl at pH 6 by reducing levels of ribosomal proteins, whereas at pH 8 there was an upregulation of ribosomal proteins compared with the reference control. The levels of two ribosomal proteins, L32 and S19, remained constant across all experimental conditions. The data supported the hypothesis that the bacterium was continually responding to the dynamic environment by modifying the proteome and optimising metabolic homeostasis. [ABSTRACT FROM AUTHOR]

Background: The requirements for magnesium (Mg) supplementation increase under regional citrate anticoagulation (RCA) because citrate acts by chelation of bivalent cations within the blood circuit. The level of magnesium in commercially available fluids for continuous renal replacement therapy (CRRT) may not be sufficient to prevent hypomagnesemia. Methods: Patients (n = 45) on CRRT (2,000 ml/h, blood flow (Qb) 100 ml/min) with RCA modality (4% trisodium citrate) using calcium free fluid with 0.75 mmol/l of Mg with additional magnesium substitution were observed after switch to the calcium-free fluid with magnesium concentration of 1.50 mmol/l (n = 42) and no extra magnesium replenishment. All patients had renal indications for CRRT, were treated with the same devices, filters and the same postfilter ionized calcium endpoint (<0.4 mmol/l) of prefilter citrate dosage. Under the high level Mg fluid the Qb, dosages of citrate and CRRT were consequently escalated in 9h steps to test various settings. Results: Median balance of Mg was -0.91 (-1.18 to -0.53) mmol/h with Mg 0.75 mmol/l and 0.2 (0.06–0.35) mmol/h when fluid with Mg 1.50 mmol/l was used. It was close to zero (0.02 (-0.12–0.18) mmol/h) with higher blood flow and dosage of citrate, increased again to 0.15 (-0.11–0.25) mmol/h with 3,000 ml/h of high magnesium containing fluid (p<0.001). The arterial levels of Mg were mildly increased after the change for high level magnesium containing fluid (p<0.01). Conclusions: Compared to ordinary dialysis fluid the mildly hypermagnesemic fluid provided even balances and adequate levels within ordinary configurations of CRRT with RCA and without a need for extra magnesium replenishment. Trial Registration: ClinicalTrials.gov Identifier: [ABSTRACT FROM AUTHOR]

The ability of mammals to feel noxious stimuli lies in a heterogeneous group of primary somatosensory neurons termed nociceptors, which express specific membrane receptors, such as the Transient Receptor Potential (TRP) family. Here, we show that one of the most important nociceptive-like pathways is conserved in the freshwater coelenterate Hydra vulgaris, the most primitive organism possessing a nervous system. In particular, we found that H. vulgaris expresses TRPM3, a nociceptor calcium channel involved in the detection of noxious heat in mammals. Furthermore, we detected that both heat shock and TRPM3 specific agonist (i.e., pregnenolone sulfate) induce the modulation of the heat shock protein 70 (HSP70) and the nitric oxide synthase (NOS), two genes activated by TRP-mediated heat painful stimuli in mammals. As expected, these effects are inhibited by a TRPM3 antagonist (i.e., mefenamic acid). Interestingly, the TRPM3 agonist and heat shock also induce the expression of nuclear transcription erythroid 2-related factor (Nrf2) and superoxide dismutase (SOD), known markers of oxidative stress; noteworthy gene expression was also inhibited by the TRPM3 antagonist. As a whole, our results demonstrate the presence of conserved molecular oxidative/nociceptive-like pathways at the primordial level of the animal kingdom. [ABSTRACT FROM AUTHOR]

The discovery of the electron in 1897 deeply impacted the nature of chemistry in the twentieth century. A revolution in the theoretical structure of chemistry as well as in the instrumental tools used in chemical analysis occurred as a result of this discovery. The impact of this revolution on tin oxide chemistry over approximately a 100 year period is the focus of this paper. Important questions addressed include the following: Are tin oxides of importance in our current society or are they only of quaint academic interest? In what way has chemistry as a discipline added to our understanding of the tin oxides and has this added any technological value to these compounds? Does the historical approach followed in this paper offer chemistry educators the opportunity to place current chemical knowledge in a broader epistemological framework? The impact of the answers to these questions on chemistry education is discussed. [ABSTRACT FROM AUTHOR]

A physicochemical characterization, including aerosol number size distribution, chemical composition and mass concentrations, of the urban fine aerosol captured in MILAN, BARCELONA and LONDON is presented in this article. The objective is to obtain a comprehensive picture of the microphysical processes involved in aerosol dynamics during the: 1) regular evolution of the urban aerosol (daily, weekly and seasonal basis) and in the day-to-day variations (from clean-air to pollution-events), and 2) the link between "aerosol chemistry and mass concentrations" with the "number size distribution". The mass concentrations of the line PM2.5 aerosol exhibit a high correlation with the number concentration of > 100nm particles N> 100 (nm/ ("accumulation mode particles") which only account for <20% of the total number concentration N of fine aerosols; but do not correlate with the number of < 100 nm particles ("ultrafine particles"), which accounts for >80% of fine particles number concentration. Organic matter and black-carbon are the only aerosol components showing a significant correlation with the ultrafine particles, attributed to vehicles exhausts emissions; whereas ammonium-nitrate, ammonium-sulphate and also organic matter and black-carbon correlate with N>100 (nm) and attributed to condensation mechanisms, other particle growth processes and some primary emissions. Time series of the aerosol DpN diameter (dN/dlogD mode), mass PM2.5 concentrations and number N> 100 (nm) concentrations exhibit correlated day to-day variations, which point to a significant involvement of condensation of semi-volatile compounds during urban pollution events. This agrees with the observation that ammonium-nitrate is the component exhibiting the highest increases from mid-to-high pollution episodes, when the highest DpN increases arc observed. The results indicates that "fine PM2.5 particles urban pollution events" tend to occur when condensation processes have made particles grow large enough to produce significant number concentrations of N> 100 (nm) ("accumulation mode particles"). In contrast, because the low contribution of utrafine particles to the line aerosol mass concentrations, high "utrafine panicles N< 100(nm) events" frequently occurs under low PM2.5 conditions. The results of this study demonstrate that vehicles exhausts emissions are strongly involved in this ultrafine particles aerosol pollution. [ABSTRACT FROM AUTHOR]

Discusses the annual review of cosmetic ingredient safety assessments for 2002/2003. Assessment of the safety of cosmetic ingredients by the Cosmetic Ingredient Review (CIR) program Expert Panel; Re-review process of the CIR Expert Panel; Ingredients the CIR Expert Panel reconsidered in 2002/2003.

Microalloyed steels have evolved in terms of their chemical composition, processing, and metallurgical characteristics since the beginning of the 20th century in the function of fabrication costs and mechanical properties required to obtain high-performance materials needed to accommodate for the growing demands of gas and hydrocarbons transport. As a result of this, microalloyed steels present a good combination of high strength and ductility obtained through the addition of microalloying elements, thermomechanical processing, and controlled cooling, processes capable of producing complex microstructures that improve the mechanical properties of steels. These controlled microstructures can be severely affected and result in catastrophic failures, due to the atomic hydrogen diffusion that occurs during the corrosion process of pipeline steel. Recently, a martensite–bainite microstructure with acicular ferrite has been chosen as a viable candidate to be used in environments with the presence of hydrogen. The aim of this review is to summarize the main changes of chemical composition, processing techniques, and the evolution of the mechanical properties throughout recent history on the use of microalloying in high strength low alloy steels, as well as the effects of hydrogen in newly created pipelines, examining the causes behind the mechanisms of hydrogen embrittlement in these steels. [ABSTRACT FROM AUTHOR]

The syntheses of two square planar nickel complexes containing the condensation and subsequently reduced products obtainedbyreacting[[Ni[(en).sub.3]][([BF.sub.4]).sub.2]andacetoneare reported. Thecomplexes5,5,7,12,12,14-hexamethyl-1(S),4(S),8(R),11(R)-tetraazacy-clotetradecane-nickel(II)[[PF.sub.6]].sub.2] and 5,5,7,12,12,14-hexamethyl-1(S),4(R),8(S),11(R)-tetraazacyclotetradecane-nickel(II)[Cl][[PF.sub.6]] labelled as [Ni[[(II).sup.SSRR]L]([PF.sub.6]).sub.2] and [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]), respectively, were found to have slightly different solubilities that allowed for their purification. The complexes were characterized by FTIR, [.sup.1]H NMR, and UV-vis spectra. Redox potentials, determined by cyclic voltammetry, established that [Ni[[(II).sup.SSRR]L]([PF.sub.6]).sub.2] exhibits a reversible oxidation ([E.sub.1/2](ox) = 0.85 V) and reduction ([E.sub.1/2](red) = -1.59 V), whereas [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]) displays an irreversible oxidation ([E.sub.pa](ox) = 1.37 V) and reversible reduction ([E.sub.1/2](red) = -1.62 V) relative to the ferrocene couple at 0.0 V. Single crystal X-ray determinations established that one of the compounds, [Ni[[(II).sup.SSRR]L]([PF.sub.6]).sub.2], contained two [PF.sub.6] anions, whereas the other compound, [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]), contained one [Cl.sup.-] and one PF6 anion. In the solid state, compound [Ni[[(II).sup.SSRR]L]([PF.sub.6]).sub.2] was held together by H-bonds between H atoms on the Ni containing dication and F atoms in the [PF.sub.6] anion. Compound [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]) crystallized in the form of dimers held together by interactions between H atoms attached to N atoms on adjacent cations binding to two [Cl.sup.-] anions in the middle with these dimers held together by further H-bonding to interstitial [PF.sub.6] anions. Complex [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]) was found to contain anagostic interactions on the bases of NMR (downfield shift in C-H protons) and structural data (2.3 < [d.sub.(H-Ni)] < 2.9 A), as well as theoretical calculations. Key words: square planar nickel complexes, crystallography, theoretical calculations, conformational isomerism, cyclic voltammetry. Nous presentons la synthese de deux complexes de nickel de structure plan carre contenant les produits d'une condensation suivie d'une reduction, obtenus par reaction du [Ni[(en).sub.3]][([BF.sub.4]).sub.2] et de l'acetone. Nous avons observe que la solubilite des complexes 5,5,7,12,12,14-hexamethyl-1(S),4(S),8(R),11(R)-tetraazacyclotetradecane-nickel(II)[[[PF.sub.6]].sub.2] et 5,5,7,12,12,14-hexamethyl-1[(S),4(R),8(S),11(R)-tetraazacyclotetradecane-nickel(II)[Cl][[PF.sub.6]], designes comme [Ni[(II).sup.SSRR]L]([PF.sub.6]).sub.2] et [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]), est le-gerement differente, ce qui permet leur purification. Nous avons caracterise ces complexes par spectroscopie FTIR, RMN [.sup.1]H et UV-visible. Les potentiels d'oxydoreduction, determines par voltamperometrie cyclique, ont permis d'etablir que le complexe [Ni[[(II).sup.SSRR]L]([PF.sub.6]).sub.2] presente un comportement d'oxydation reversible ([E.sub.1/2][ox] = 0,85 V) et de reduction reversible ([E.sub.1/2][red] = -1,59 V), tandis que le complexe [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]) presente un comportement d'oxydation irreversible ([E.sub.pa][ox] = 1,37 V) et de reduction reversible ([E.sub.1/2][red] = -1,62 V) par rapport au couple ferrocene a 0,0 V. Les etudes de radiocristallographie sur monocristal ont montre que l'un des composes, le [Ni[[(II).sup.SSRR]L]([PF.sub.6]).sub.2], contenait deux anions [PF.sub.6], tandis que l'autre, le [Ni[[(II).sup.SRSR]L](Cl)([PF.sub.6]), contenait un anion Cl- et un anion [PF.sup.-.sub.6]. A l'etat solide, la cohesion du compose [Ni[(II).sup.SSRR]L]([PF.sub.6]).sub.2] etait maintenue par des liaisons hydrogene entre les atomes d'hydrogene du dication de Ni et les atomes de F de l'anion [PF.sup.-.sub.6]. Le compose [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]) a cristallise sous forme de dimeres maintenus ensemble par des interactions entre les atomes de H lies aux atomes de N sur les cations et deux anions Cl- adjacents situes entre les deux cations, d'autres liaisons hydrogene avec les anions [PF.sub.6] interstitiels contribuant a maintenir davantage la cohesion des dimeres. Nous avons pu etablir que le complexe [Ni[(II).sup.SRSR]L](Cl)([PF.sub.6]) comportait des interactions anagostiques d'apres les donnees de RMN (deblindage des protons C-H) et les donnees structurales (2,3 < [d.sub.[H-Ni]] < 2,9 A), et d'apres les calculs theoriques. [Traduit par la Redaction] Mots-cles : complexes de nickel de structure plan carre, cristallographie, calculs theoriques, isomerisme conformationnel, voltamperometrie cyclique., Introduction The syntheses and structures of macrocyclic Schiff base--amine complexes of nickel(II) (1) were comprehensively described and characterized by Curtis (2-5) and consisted of a novel template approach, as shown [...]

Reaction of [Rh([micro]-Cl)(CO)(TXPB)] (1; TXPB = 2,7-di-(ert-butyl-5-diphenylboryl-4-diphenylphosphino-9,9-dimethylthioxanthene) with [NaBH.sub.4] yielded square planar [Rh([x-H)(CO)(TXPB)] (2) in which the hydride ligand bridges between rhodium and the borane unit of TXPB. The Rh-H, Rh-B, and Rh-[C.sub.ipso] distances are short at 1.84(5), 2.456(6), and 2.568(5) A, respectively, whereas the B-H bond, 1.59(6) A, falls at the longer end of the usual range. Compound 2 is compared with the previously reported series of rhodium TXPB complexes: [RhX(CO)(TXPB)] {X = F(3), Cl (1), Br (4),I(5)}. Compound 4 in this series features the only crystallo-graphically characterized example of an M-Br-[BR.sub.3] interaction, and to expand this area, [NiBr([[micro]-Br)(TXPB)] (6) was prepared via the reaction of [[NiBr.sub.2][(dme).sub.2]] (dme = 1,2-dimethoxyethane) with TXPB. An X-ray crystal structure of light purple 6 revealed a square-planar geometry with a strong B-Br interaction {B-Br = 2.311(6) A; [SIGMA](C-B-C) = 344.5(7)[degrees]}. An [.sup.11]B NMR chemical shift of 23 ppm was observed for 6, indicating that an appreciable B-Br interaction is maintained in solution. No signals were observed in the [.sup.31]P{[.sup.1]H} NMR spectrum at room temperature, whereas a broadened [.sup.31]P signal was observed at -20 [degrees]C, evolving into a sharp singlet at -67 [degrees]C. This behaviour suggests that at room temperature, square planar 6 exists in equilibrium with a paramagnetic tetrahedral isomer, present at a level below that detectable through Evans magnetic measurements. Key words: ambiphilic ligands, pendant boranes, rhodium, nickel, bridging ligands. La reaction du [Rh([micro]-Cl)(CO)(TXPB)] (1; TXPB = 2,7-di-tert-butyl-5-diphenylboryl-4-diphenylphosphino-9, 9-dimethylthioxanthene) avec le [NaBH.sub.4] a produit le complexe de structure plan carre [Rh([micro]-H)(CO)(TXPB)] (2) dans lequel le rhodium et l'unite borane du TXPB sont connectes le ligand hydrure. Les distances Rh-H, Rh-B et Rh-Cipso sont courtes {1,84(5), 2,456(6) et 2,568(5) A, respectivement}, tandis que la liaison B-H {1,59(6) A} se situe a l'extremite superieure de la plage habituelle des longueurs de liaisons. Nous avons compare le compose2 a la serie de complexes de rhodium-TXPB publiee precedemment: [RhX(CO)(TXPB)] {X = F(3), Cl (1), Br (4), I (5)}. Le compose 4 represente dans cette serie le seul exemple d'une interaction M-Br-BR3 caracterisee par cristallographie. Afin d'etendre ce domaine, nous avons prepare le complexe [NiBr([x-Br)(TXPB)] (6) par reaction du [[NiBr.sub.2][(dme).sub.2]] (dme = 1,2-dimethoxyethane) avec le TXPB. La structure cristalline du compose violet clair 6 a revele une geometrie plan carre et une forte interaction B-Br {B-Br = 2,311(6)A; [SIGMA](C-B-C) = 344,5(7)[degrees]}. Le complexe 6 a montre en RMN [.sup.11]Bun deplacement chimique de 23 ppm, signe qu'une interaction B-Br appreciable est maintenue en solution. En RMN [.sup.31]P{[.sup.1]H}, nous n'avons observe aucun signal a temperature ambiante, alors qu'a -20 [degrees]C, nous avons observe un signal large de [.sup.31]P, se transformant en singulet bien defini a -67 [degrees]C. Ce comportement permet de penser qu'a temperature ambiante, le complexe 6 de geometrie plan carre existe en equilibre avec un isomere tetraedrique paramagnetique qui serait present en concentrations indetectables par des mesures de la susceptibilite magnetique selon la methode d'Evans. [Traduit par la Redaction] Mots-cles: ligands amphiphiles, boranes appendiculaires, rhodium, nickel, ligands pontants., Introduction Early efforts in transition metal-borane chemistry were directed towards the synthesis and characterization of complexes featuring direct [[eta].sup.1]B-coordination of a borane to the metal centre. Such complexes proved elusive [...]

Abstract: A sequential Sonogashira cross-coupling/Pd-mediated oxidative homocoupling strategy affords two expanded dehydrobenzoannulene (DBA) structures containing two [14]DBAs fused to an [18]DBA core. Noticeable differences in the absorption and emission spectra [...]

A method is proposed for the gas-chromatographic determination of glycols as bis(diethoxyphosphoryl)alkanes formed by the Atherton--Todd reaction with diethyl phosphite. Gas-chromatographic and mass-spectrometric characteristics of the derivatives obtained are studied. Conditions of the phosphorylation reaction are optimized. The method is applied to the determination of the residual amounts of glycols in oligomeric glycol-o-phthalates. Keywords: gas chromatography, mass spectrometry, glycols, phosphorylation, Glycols are used in chemical, aviation, electrotechnical, textile, oil and gas, and other industries both individually and as components of technical fluids with low freezing points, for example, in antifreeze [...]

The optimized molecular structures, conformational analyses, vibrational (IR) frequencies and their assignments, maximum electronic absorption wavelengths (gas phase and in ethanol solvent), ¹H and [sup.13]C NMR chemical shift values (gas phase and in CD[Cl.sub.3] solvent), HOMO-LUMO analysis, molecular electrostatic potential surfaces, and nonlinear optical properties of flufenpyr ([C.sub.14][H.sub.9]Cl[F.sub.4][N.sub.2][O.sub.4]) and amipizone ([C.sub.14][H.sub.16]Cl[N.sub.3]O) compounds that have many biological activities have been calculated using the DFT/B3LYP, B3PW91, and HSEH1PBE methods with the 6-311G(d,p) basis set in the ground state. A comparison among the results calculated at the mentioned levels indicates that the HSEH1PBE calculations give usually greater values compared with the others in terms of vibrational frequencies, the maximum electronic absorption wavelengths, and HOMO-LUMO energy gaps of the title compounds. Key words: vibrational spectroscopy, ¹H and [sup.13]C NMR chemical shifts, flufenpyr, amipizone, density functional theory method. Le flufenpyr ([C.sub.14][H.sub.9]Cl[F.sub.4][N.sub.2][O.sub.4]) et l'amipizone ([C.sub.14][H.sub.16]Cl[N.sub.3]O) sont des composes biologiquement actifs a l'egard de multiples cibles. Au moyen des methodes DFT/B3LYP, B3PW91 et HSEH1PBE, en utilisant la base 6-311G(d,p) a l'etat fondamental, nous avons calcule les parametres suivants relativement a ces composes : structures moleculaires optimisees, analyses conformationnelles, frequences vibrationnelles (IR) et assignation de leurs pics, longueurs d'onde de l'absorption electronique maximale (en phase gazeuse et en solution dans l'ethanol), deplacements chimiques en RMN¹H et [sup.13]C (en phase gazeuse et en solution dans le CD[Cl.sub.3]), analyse HOMO-LUMO, surfaces de potentiel electrostatique moleculaire et proprietes optiques non lineaires. La comparaison des resultats calcules aux niveaux mentionnes indique que les calculs HSEH1PBE donnent habituellement des valeurs plus elevees que les autres methodes pour ce qui est des frequences vibrationnelles, des longueurs d'onde de l'absorption electronique maximale et des largeurs de bande interdite HOMO-LUMO pour les composes susmentionnes. [Traduit par la Redaction] Mots-cles: spectroscopie vibrationnelle, deplacements chimiques en RMN ¹H et [sup.13]C, flufenpyr, amipizone, methode de la theorie de la fonctionnelle de la densite., Introduction The 3(2H)-pyridazinones as pyridazine derivatives contain two adjacent nitrogen atoms at the 1 and 2 positions in a six-membered ring and a carbonyl group at the 3 position and [...]