Evidence for organosulfates in secondary organic aerosol

Recent work has shown that particle-phase reactions contribute to the formation of secondary organic aerosol (SOA), with enhancements of SOA yields in the presence of acidic seed aerosol. In this study, the chemical composition of SOA from the photooxidations of alpha-pinene and isoprene, in the presence or absence of sulfate seed aerosol, is investigated through a series of controlled chamber experiments in two separate laboratories. By using electrospray ionization-mass spectrometry, sulfate esters in SOA produced in laboratory photooxidation experiments are identified for the first time. Sulfate esters are found to account for a larger fraction of the SOA mass when the acidity of seed aerosol is increased, a result consistent with aerosol acidity increasing SOA formation. Many of the isoprene and alpha-pinene sulfate esters identified in these chamber experiments are also found in ambient aerosol collected at several locations in the southeastern U.S. It is likely that this pathway is important for other biogenic terpenes, and may be important in the formation of humic-like substances (HULIS) in ambient aerosol.     

Convergence of the inductive and deductive models in the measurement of reasoning abilities.

Reviews evidence concerning the congruence of the inductive and deductive models in logic and presents support for this congruence in the context of new test items designed to exemplify general-to-particular induction. Data from the Professional and Administrative Career Examination corroborate the logical foundations of deduction and induction as convergent models. Factor analysis of the items demonstrated factorial convergence, which lends additional support to the postulate of convergence. Implications for the understanding of cognitive processes and for psychometric practice are discussed in relation to such issues as the use of verbal and nonverbal test media, redundancy of measurement, and problem-solving strategies. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Douro wine region: a cluster approach

The globalization of the wine industry needs to be perceived as a challenge and an opportunity to innovate by traditional European producers’ countries, like Portugal, characterized by a terroir model, that is, an economic structure supported by a large number of grape growers, small and medium wine firms and high public regulation, to compete in international markets. Using a cluster approach, this article presents the case of the most important Portuguese wine region, the Demarcated Douro Region (DDR), which is a strong reference of terroir and known for producing Port wine. To increase its competitiveness in the world wine market, the DDR needs to evolve from an organized to an innovative cluster.     

Using degradation data to assess reliability: a case study on train wheel degradation

Degradation experiments are usually used to assess the lifetime distribution of highly reliable products, which are not likely to fail under the traditional life tests or accelerated life tests. In such cases, if there exist product characteristics whose degradation over time can be related to reliability, then collecting ‘degradation data’ can provide information about product reliability. In general, the degradation data are modeled by a nonlinear regression model with random coefficients. If we can obtain the estimates of parameters under the model, then the failure‐time distribution can be estimated. In order to estimate those parameters, three basic methods are available, namely, the analytical, numerical and the approximate. They are chosen according to the complexity of the degradation path model used in the analysis. In this paper, the numerical and the approximate methods are compared in a simulation study, assuming a simple linear degradation path model. A comparison with traditional failure‐time analysis is also performed. The mean‐squared error of the estimated 100pth percentile of the lifetime distribution is evaluated for each one of the approaches. The approaches are applied to a real degradation data set. Copyright © 2008 John Wiley & Sons, Ltd.     

Understanding the silylation reaction of multi-walled carbon nanotubes

Functional organosilanes were appended, in aprotic and anhydrous conditions, onto multi-walled carbon nanotubes (MWCNTs) previously submitted to three different oxidative treatments: acid, acid with subsequent thermal treatment at 400 °C and 5% O₂/N₂ treatment at 500 °C. The materials were characterised by X-ray photoelectron spectroscopy, elemental analysis, temperature programmed desorption, Fourier transform infrared spectroscopy, thermogravimetry, nitrogen adsorption isotherms at −196 °C and scanning electron microscopy. The techniques provided a correlation between the type and oxygen contents present in the oxidised MWCNTs and the silylation reaction efficiency, leading to a comprehensive overview of the reaction mechanism and materials structure/composition. The highest silylation reaction efficiencies were achieved with the aminosilane in all the oxidised materials and with mercaptosilane in the acid oxidised MWCNTs with nearly 4% Si insertion, whereas for the other organosilanes values lower than 2% were observed. The silylation mechanism was found to proceed through reaction of the alkoxy moieties from the organosilane with phenol surface groups from the MWCNTs; in the case of aminosilane for all MWCNTs and mercaptosilane in acid oxidised MWCNTs, it also occurred by reaction with the carbonyl surface groups. Furthermore, for these latter materials a polymerisation side-reaction was proposed as a parallel functionalisation pathway.     

Selective catalytic transformations of methanol to C2-C3 hydrocarbons over the new zeolite type LZ 132

The small pore zeolite HLZ 132 exhibits, in comparison with other zeolites, an increased selectivity for the transformation of methanol to ethylene in the reaction temperature range 350–500 °C: the weight ratio of C₂H₄ to C₃H₆ in the products ranges between 1 and 4 at WHSV=2 h^–1. Besides the effect of the reactant shape selectivity this fact may be interpreted by the participation of the asymmetrical methoxy groups in the surface as well as by proton-donor centres of lower acidity which do not catalyze the oligomerization of ethylene but which do the more basic molecule of propylene, thereby generating polyene-type coke.     

Radiation synthesis of hydrogels based on carboxymethyl cellulose and its application in removal of pollutants from wastewater

Synthesis of carboxymethyl cellulose‐g‐methacrylic acid/acrylamide Poly(CMC/MAAc:AAm) hydrogel was carried out using direct radiation copolymerization technique at ambient temperature. The gel (%) increased with increasing the content of AAm till level off at Poly(CMC/MAAc:AAm) (1/50:50 wt%) hydrogel and the swelling behavior found to be increased with increasing MAAc content in the hydrogel composition up to Poly(CMC/MAAc:AAm) (1/60:40 wt%). The grafting yield, grafting ratio, swelling behavior, and the thermal stability of Poly(CMC/MAAc:AAm) binary system are higher than those reported in our previous study by the same author which described the individual grafting of acrylamide (AAm) and methacrylic acid (MAAc) with different concentration onto carboxymethyl cellulose (CMC) using direct radiation grafting technique. The swelling kinetics and diffusion mechanism indicate that the water penetration obey non‐Fickian transport mechanism. The characterization of the prepared hydrogel was evaluated using Fourier transform infrared, X‐ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The analyses by different analytical tools confirmed the successful grafting of both MAAc and AAm onto CMC. The adsorption capacity of Poly(CMC/MAAc:AAm) (1/60:40 wt%) hydrogel toward metal ions such as Cu⁺² and Co⁺², dyes such as acid blue dye and methyl green have been investigated. J. VINYL ADDIT. TECHNOL., 25:E35–E43, 2019. © 2017 Society of Plastics Engineers     

Serious conduct problems in the children of adolescent mothers: Disentangling confounded correlations.

Early motherhood (r?=?.33) with the number of Diagnostic and Statistical Manual of Mental Disorders (DSM-III) symptoms of conduct disorder in a sample of 253 boys (aged 6–13 yrs) who had been referred to outpatient clinics. The following models were compared using path analysis: (1) Teenage motherhood, parental antisocial personality, and socioeconomic status (SES) each contribute uniquely to the prediction of childhood conduct problems; (2) teenage motherhood mediates the association of SES and parental antisocial personality with child conduct problems; and (3) teenage motherhood is spuriously related with child conduct problems because of common associations with SES and parental antisocial personality. Model (3) best fit the data. Similar results were obtained whether maternal age at the birth of the firstborn child or the proband child was used to define maternal age and when teenage motherhood was defined as giving birth at     

Release Kinetics of Tretinoin from Dermatological Formulations

Tretinoin, or retinoic acid, can be used in the treatment of a variety of skin diseases, depending on its concentration. Formulations containing tretinoin 1 % have been used in the therapy of malignant cutaneous diseases, namely, Kaposi 's syndrome. In lower concentrations, it has been used in antiacne formulations and in the treatment of anti-aging effects on photodamaged skin. The aim of the present study was to determine the variation profile of in vitro release of tretinoin, in order to establish the drug's partition coefficient between its carrier and the stratum corneum. The samples studied were formulations of tretinoin 0, 05% in carbopol 940 (a synthetic polymer), sodium carboxymethylcellulose (a semisynthetic polymer), and carob gum (a natural polymer) gels. The release profiles obtained from these formulations were compared to release profiles of retinoid creams. The formulations studied exhibited both good chemical and physical stabilities when submitted to rheological determinations, pH measurements, and drug dosage, throughout a 6-month period. The obtained results show that identical polymer viscosities result in identical release profiles; however, the release kinetics of tretinoin varies strongly in the way in which the drug is incorporated in the formulation (whether it is a solution or a suspension).     

Salting-out in Aqueous Solutions of Ionic Liquids and K3PO4: Aqueous Biphasic Systems and Salt Precipitation

The salting-out effect produced by the addition of potassium phosphate, K₃PO₄ to aqueous solutions of water-miscible ionic liquids, viz. 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, or 1-alkyl-3-methylimidazolium chloride (alkyl = butyl, octyl or decyl) is investigated. The effects are analyzed using both the corresponding temperature–composition pseudo-binary and composition ternary phase diagrams. Different regions of liquid-liquid and solid-liquid phase demixing are mapped. The phase behavior is interpreted taking into account the complex and competing nature of the interactions between the ionic liquid, the inorganic salt and water. In the case of solutions containing 1-octyl- or 1-decyl-3-methylimidazolium chloride, the smaller magnitude of the salting-out effects is explained in terms of the possibility of self-aggregation of the ionic liquid.