Cumulative contextual risk at birth in relation to adolescent substance use, conduct problems, and risky sex: General and specific predictive associations in a Finnish birth cohort

Background—Research indicates that risk factors cluster in the most vulnerable youth, increasing their susceptibility for adverse developmental outcomes. However, most studies of cumulative risk are cross-sectional or short-term longitudinal, and have been based on data from the United States or the United Kingdom. Using data from the Northern Finland Birth Cohort 1986 Study (NFBC1986), we examined cumulative contextual risk (CCR) at birth as a predictor of adolescent substance use and co-occurring conduct problems and risky sex to determine the degree to which CCR predicts specific outcomes over-and-above its effect on general problem behavior, while testing for moderation of associations by gender. Methods—Analyses of survey data from 6963 participants of the NFBC1986 followed from the prenatal/birth period into adolescence were conducted using structural equation modeling. Results—CCR had long-term positive associations with first-order substance use, conduct problems, and risky sex factors, and, in a separate analysis, with a second-order general problem behavior factor. Further analyses showed that there was a positive specific effect of CCR on risky sex, over-and-above general problem behavior, for girls only. Conclusions—This study, conducted within the Finnish context, showed that CCR at birth had long-term general and specific predictive associations with substance use and co-occurring problem behaviors in adolescence; effects on risky sex were stronger for girls. Results are consistent with the hypothesis that early exposure to CCR can have lasting adverse consequences, suggesting the need for early identification and intervention efforts for vulnerable children

Cumulative contextual risk at birth in relation to adolescent substance use, conduct problems, and risky sex: General and specific predictive associations in a Finnish birth cohort

Background—Research indicates that risk factors cluster in the most vulnerable youth, increasing their susceptibility for adverse developmental outcomes. However, most studies of cumulative risk are cross-sectional or short-term longitudinal, and have been based on data from the United States or the United Kingdom. Using data from the Northern Finland Birth Cohort 1986 Study (NFBC1986), we examined cumulative contextual risk (CCR) at birth as a predictor of adolescent substance use and co-occurring conduct problems and risky sex to determine the degree to which CCR predicts specific outcomes over-and-above its effect on general problem behavior, while testing for moderation of associations by gender. Methods—Analyses of survey data from 6963 participants of the NFBC1986 followed from the prenatal/birth period into adolescence were conducted using structural equation modeling. Results—CCR had long-term positive associations with first-order substance use, conduct problems, and risky sex factors, and, in a separate analysis, with a second-order general problem behavior factor. Further analyses showed that there was a positive specific effect of CCR on risky sex, over-and-above general problem behavior, for girls only. Conclusions—This study, conducted within the Finnish context, showed that CCR at birth had long-term general and specific predictive associations with substance use and co-occurring problem behaviors in adolescence; effects on risky sex were stronger for girls. Results are consistent with the hypothesis that early exposure to CCR can have lasting adverse consequences, suggesting the need for early identification and intervention efforts for vulnerable children

Surfactant-directed syntheses of mesostructured zinc imidazolates: formation mechanism and structural insights

Supramolecular templating techniques have been widely used to direct the formation of porous materials with the goal of introducing permanent mesoporosity. While surfactant-directed self-assembly has been exploited for inorganic materials such as titania, silica, organosilica, and zeolites, it has rarely been applied to metal-organic frameworks (MOFs) and coordination polymers. Here we introduce a new family of gemini surfactant-directed zinc imidazolates, referred to as mesostructured imidazolate frameworks (MIFs), and present a detailed study on the influence of different gemini-type surfactants on the formation mechanism and structures of the resulting zinc imidazolates. The proposed formation mechanism for MIF-type materials involves co-assembly and crystallization processes that yield lamellar mesostructured imidazolate frameworks. Understanding and controlling such processes also has implications for the syntheses of microporous zinc imidazolate framework (ZIF) materials, whose formation can be suppressed in surfactant-rich solutions, whereas formation of MIF materials is favored in the presence of surfactants and triggered by the addition of halogenides. Solid-state 2D 13C1H HETCOR NMR measurements on prototypic CTAB-directed MIF-1 establish that the head group moieties of the surfactant molecules interact strongly with the zinc-imidazolate-bromide sheets. Additionally, the NMR analyses suggest that MIF-1 has a significant fraction of surfactant molecules that are interdigitated between the zinc-imidazolate-bromide sheets with an antiparallel stacking arrangement, consistent with the high thermal and chemical stability of the MIF hybrid materials

Doped Mesoporous Silica Fibers: A New Laser Material

The fabrication of a laser based on mesoporous fibers is shown to be possible, demonstrating for the first time that mesostructural systems can be applied as advanced optical materials. The amplification of a guided mode in the fiber and the resulting, gain-narrowed emission (illustrated on the cover of this issue) are reported. It is stressed that the system used—a composite containing the dye rhodamine 6G—is a relatively simple type of laser material and better results can be expected in the future with different types of lasing guests in mesoporous fibers

Directed synthesis of organic/inorganic composite structures

The impact of the discovery of the synthesis of periodic mesoporous material using amphiphilic surfactants is apparent from the demographics of papers that have appeared in this area. In addition to providing for the first time access to high surface area, monodispersed mesopores (1nm to > 10nm), the research has provided, in a more generic sense, a new synthesis paradigm on the ways in which to bring together spatially distinct, nanostructured organic, and inorganic arrays into two- and three-dimensional periodic, composite structures. Designed materials synthesis and properties based on the molecular level interplay of the kinetics and energetics of organic and inorganic domain and interface assembly are of vital interest to many areas including biomineralization, conducting and optical display polymer composites, chemical sensors, fine chemical and bio-catalysis, and the creation of composite phases with useful mechanical and thermal properties for insulation and packaging applications. It is clear that this discovery is a major entry not only in the “breakthrough” library of zeolite and molecular sieve syntheses, but also in advancing the field of materials syntheses in general. This chapter focuses on some observations concerning this composite synthesis paradigm. The presentation is admittedly only a selected sampling, with some brief excursions into implications related to biomineralization and porous materials design at longer (10 nm to 1000nm) length scales

Películas fluorescentes azules basadas en derivados de poli-2,7-fluorenofenilideno

Quaternization of poly-(9,9-bis(6’-bromohexyl)fluorenephenylene by treatment with trimethylamine gas was used to obtain a water soluble ammonium salt copolymer. The neutral copolymer containing fluorene/phenylene alternating repeating units was obtained by a palladiumcatalyzed Suzuki coupling reaction. This strategy could be applied to prepare water soluble conjugated polymers with the ability to change the charge functionality. The polymers were characterized by gel permeation chromatography (GPC), 1H and 13C NMR spectroscopy, FT-IR spectroscopy, and thermogravimetric analysis (TGA). The neutral polymer was stable to over 300ºC, while the cationic polymer begins to degrade at 120ºC with a progressive loss of mass at 290ºC. The optical properties of the polymers were investigated in solution and solid phases by UV/VIS and fluorescent spectroscopy. Mesoporous silica thin films were prepared as a host matrix for the fluorescent copolymers.<br><br>La cuaternización del poli-(9,9-bis(6’-bromohexilo)fluorenofenileno) por tratamiento de trimetilamina gaseosa se emplea para obtener una sal de amonio del copolímero precursor soluble en agua. El copolímero neutro contiene unidades alternantes repetitivas de fluoreno/ fenilideno obtenidas mediante una acoplamiento de Suzuki con Pd (II). Los polímeros se caracterizaron por cromatografía de permeación (GPC), espectroscopia RMN de 1H y 13C , espectroscopia IR transformada de Fourier y análisis termogravimétrico (ATG). El polímero neutro mantiene la estabilidad hasta los 300ºC, mientras el derivado catiónico comienza a descomponer a 120ºC, con una progresiva perdida de masa hasta los 290ºC. Las propiedades ópticas de los polímeros se estudiaron en disolución y en películas mediante espectroscopias UV/VIS y de fluorescencia. Las películas delgadas de sílice mesoporosa se prepararon como materiales receptores de los copolímeros fluorescentes

Surface effects on the structure and mobility of the ionic liquid C(6)C(1)ImTFSI in silica gels

We report on how the dynamical and structural properties of the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (C(6)C(1)ImTFSI) change upon different degrees of confinement in silica gels. The apparent diffusion coefficients of the individual ions are measured by H-1 and F-19 pulsed field gradient nuclear magnetic resonance (PFG-NMR) spectroscopy, while the intermolecular interactions in the ionogels are elucidated by Raman spectroscopy. In addition, the local structure of the ionic liquid at the silica interface is probed by solid-state NMR spectroscopy. Importantly, we extend this study to a wider range of ionic liquid-to-silica molar ratios (x) than has been investigated previously, from very low (high degree of confinement) to very high (liquid-like gels) ionic liquid contents. Diffusion NMR measurements indicate that a solvation shell, with a significantly lower mobility than the bulk ionic liquid, forms at the silica interface. Additionally, the diffusion of the C(6)C(1)Im(+) and TFSI- ions decreases more rapidly below an observed molar ratio threshold (x < 1), with the intrinsic difference in the self-diffusion coefficient between the cation and anion becoming less pronounced. For ionic liquid molar ratio of x < 1, Raman spectroscopy reveals a different conformational equilibrium for the TFSI- anions compared to the bulk ionic liquid, with an increased population of the cisoid isomers with respect to the transoid. Concomitantly, at these high degrees of confinement the TFSI- anion experiences stronger ion-ion interactions as indicated by the evolution of the TFSI- characteristic vibrational mode at similar to 740 cm(-1). Furthermore, solid-state 2D Si-29{H-1} HETCOR NMR measurements establish the interactions of the ionic liquid species with the silica surface, where the presence of adsorbed water results in weaker interactions between Si-29 surface moieties and the hydrophobic alkyl protons of the cationic C(6)C(1)Im(+) molecules

Determination of molecular orientational order in cold- stretched poly (p-phenylene vinylene) thin films by DECODER C- 13 NMR

The properties of polyp-phenylene vinylene) (PPV) films depend on the degree of orientational order present in the films. Recently, Dermaut et al. reported a novel cold-stretching technique (Macromolecules 33, 5634-5637 (2000)) in which chain alignment can be introduced into PPV precursor films by uniaxially stretching them prior to the thermal elimination reaction that forms PPV. The two-dimensional direction exchange with correlation for orientation-distribution evaluation and reconstruction (DECODER) C-13 NMR technique was applied to both unstretched PPV films and PPV films that were uniaxially cold stretched to a draw ratio lambda = l/l(0) = 5. The unstretched films were found to be moderately ordered, comprised of a component present at 80% with a Gaussian distribution of 60degrees fwhm, while the remaining 20% is isotropically distributed. A distribution of 9 3 fwhm was measured by NMR in good agreement with IR dichroism measurements for the uniaxially cold-stretched films, establishing that a high degree of orientational order can be introduced by cold stretching PPV films. (C) 2002 Elsevier Science (USA)