Preparation and layer-by-layer self-assembly of positively charged multiwall carbon nanotubes

The report described a method of more stably dispersing oxidized carbon nanotubes (CNTs) by forming complex with polycation and the layer-by-layer self-assembly behavior of the complex with polyanion was studied. The properties of the self-assembled multilayer film containing carbon nanotubes were studied. Cyclic voltammetry, UV-vis-NIR spectroscopy, electrochemical impedance spectroscopy and scanning electron microscopy were used for characterization of film assembly. UV-vis-NIR spectroscopy and cyclic voltammetry study indicated the uniform growth of the film. Electrochemical impedance spectroscopy results showed that incorporating of carbon nanotubes in the polyelectrolyte multilayers; decreased in the electron-transfer resistance R, indicating more favorable electrochemical reaction interface. The electrocatalytic property of the multilayer modified electrode to NADH was investigated mainly with different numbers of the bilayers; and the results showed that along with the increase of the assembled bilayers the overpotential of NADH oxidation decreased. The detection lit-nit Could reach 6 mu M at a detection potential of 0.4 V.

Self-assembled monolayers of novel surface-bound dendrons: Peripheral structure determines surface organization

The synthetic and functional versatility of dendrimers and their well-defined shapes make them attractive molecules for surface modification. We synthesized six structurally very similar surface-bound dendrons and used them as building blocks for the preparation of self-assembled monolayers (SAMs) on a gold surface. We studied the effects of the surface-bound dendron's main structure, peripheral substituents, and the coadsorption process on its self-assembling behavior. Using scanning tunneling microscopy (STM), we observed nanostripes for SAMs of the surface-bound dendron consisting of symmetrical benzene rings. When we changed the symmetrical dendron's structure slightly, by increasing or decreasing the numbers of benzene rings at one wedge, we found no ordered structures were formed by the asymmetrical dendrons. We also introduced two kinds of substituents, heptane chains and oligo(ethylene oxide) chains, to the symmetrical dendron's periphery. Heptane chains appear to enhance the interaction between symmetrical backbones, leading to the formation of stripes, while oligo(ethylene oxide) chains appear to weaken the interaction between symmetrical backbones, resulting in a homogeneous structure. Dendrons with both heptane and oligo(ethylene oxide) chains exhibit nanophase separation in a confined state, leading to the formation of a honeycomb structure.

Preparation and characterization of self-assembled monolayers of trichlorogermanyl propanoic acid and its derivatives

Self-assembled monolayers(SAMs) of trichlorogermanyl propanoic acid derivatives on hydroxylated silicon substrates are prepared for the first time. Contact angle measurement, ellipsometry and X-ray photoelectron spectrometry(XPS) are used to characterize these SAMs, It is demonstrated that a quasi-2D network is formed on the surface of the substrate after molecules adsorbed on it. The molecular chains have certain tilt angles to the substrate surface, The wettabilities of the SAMs are various,because the molecules adsorbed and liquids used in the experiments are different. It can be concluded that trichlorogermanes have similar self-assembly behavior as trichlorosilanes, Four SAMs are studied together: they are acid, ethyl, butyl and hexyl surfaces whose results are of good consistency.

Flexible and robust run-time configuration for self-managing systems

This paper describes a methodology for deploying flexible dynamic configuration into embedded systems whilst preserving the reliability advantages of static systems. The methodology is based on the concept of decision points (DP) which are strategically placed to achieve fine-grained distribution of self-management logic to meet application-specific requirements. DP logic can be changed easily, and independently of the host component, enabling self-management behavior to be deferred beyond the point of system deployment. A transparent Dynamic Wrapper mechanism (DW) automatically detects and handles problems arising from the evaluation of self-management logic within each DP and ensures that the dynamic aspects of the system collapse down to statically defined default behavior to ensure safety and correctness despite failures. Dynamic context management contributes to flexibility, and removes the need for design-time binding of context providers and consumers, thus facilitating run-time composition and incremental component upgrade.

On the self-aggregation and fluorescence quenching aptitude of surfactant ionic liquids

The aggregation behavior in aqueous solution of a number of ionic liquids was investigated at ambient conditions by using three techniques: fluorescence, interfacial tension, and H-1 NMR spectroscopy. For the first time, the fluorescence quenching effect has been used for the determination of critical micelle concentrations. This study focuses on the following ionic liquids: [C(n)mpy]Cl (1-alkyl-3-methylpyridinium chlorides) with different linear alkyl chain lengths (n = 4, 10, 12, 14, 16, or 18), [C(12)mpip]Br (1-dodecyl-1-methylpiperidinium bromide), [C(12)mpy]Br (1-dodecyl-3-methylpyridinium bromide), and [C(12)mpyrr]Br (1-dodecyl-1-methylpyrrolidinium bromide). Both the influence of the alkyl side-chain length and the type of ring in the cation (head) on the CMC were investigated. A comparison of the self-aggregation behavior of ionic liquids based on 1-alkyl-3-methylpyridinium and 1-alkyl-3-methylpyridinium cations is provided. It was observed that 1-alkyl-3-methylpyridinium ionic liquids could be used as quenchers for some fluorescence probes (fluorophores). As a consequence, a simple and convenient method to probe early evidence of aggregate formation was established.

Privacidad e intimidad en las interacciones virtuales

El presente trabajo es una revisión de la literatura de investigación en Ciberpsicología centrada en las categorías de privacidad, intimidad, identidad y vulnerabilidad, y en la forma como estas se desarrollan en las redes sociales virtuales. Los principales hallazgos indicaron que son los jóvenes quienes dedican gran parte de su tiempo a interactuar en dichas redes, y a su vez, dado el manejo que les dan, tienen mayor exposición ante los posibles riesgos de estas, como el matoneo, las conductas auto lesivas, la explotación sexual y los trastornos de la alimentación. Se describen estos riesgos y se proponen posibles soluciones.

Impact of an empowerment-based parent education program on the reduction of youth suicide risk factors

Purpose: To evaluate the impact of parent education groups on youth suicide risk factors. The potential for informal transmission of intervention impacts within school communities was assessed.

Methods: Parent education groups were offered to volunteers from 14 high schools that were closely matched to 14 comparison schools. The professionally led groups aimed to empower parents to assist one another to improve communication skills and relationships with adolescents. Australian 8th-grade students (aged 14 years) responded to classroom surveys repeated at baseline and after 3 months. Logistic regression was used to test for intervention impacts on adolescent substance use, deliquency, self-harm behavior, and depression. There were no differences between the intervention (n = 305) and comparison (n = 272) samples at baseline on the measures of depression, health behavior, or family relationships.

Results: Students in the intervention schools demonstrated increased maternal care (adjusted odds ratio [AOR] 1.9), reductions in conflict with parents (AOR .5), reduced substance use (AOR .5 to .6), and less delinquency (AOR .2). Parent education group participants were more likely to be sole parents and their children reported higher rates of substance use at baseline. Intervention impacts revealed a dose-response with the largest impacts associated with directly participating parents, but significant impacts were also evident for others in the intervention schools. Where best friend dyads were identified, the best friend’s positive family relationships reduced subsequent substance use among respondents. This and other social contagion processes were posited to explain the transfer of positive impacts beyond the minority of directly participating families.

Conclusions: A whole-school parent education intervention demonstrated promising impacts on a range of risk behaviors and protective factors relevant to youth self-harm and suicide.

Self-assembly and film stability of a micelle of a single-chain quaternary ammonium amphiphile containing azobenzene on mica

The self-assembling behavior of a single-chain quaternary ammonium amphiphile bearing azobenzene (C₁₂AzoC₆N⁺) on freshly cleaved mica sheet has been investigated by atomic force microscopy (AFM) method. Confocal microscopic Raman spectra confirm the adsorption of the self-assembled monolayer structure. Ex-situ AFM reveals that C₁₂AzoC₆N⁺ forms branch-like stripes indicating the fusion and reorganization of the micelles during drying in air as the in-situ AFM has revealed that surfactant forms spherical micelles on the mica surface. The nano-sized surface structure is strongly dependent on the change of molecular structure, which resulted from photo-induced isomerization. The nano-sized stripe is quite stable even being annealed at 90 °C for 4 h.

Suicidal intent within an acute Australian self-harming cohort

The relationship between predisposing risk factors and precipitating life events of individuals presenting to an emergency department with Deliberate Self-Harm was investigated. Poor mental health and childhood abuse were related to suicide intent, only individuals' perceptions regarding their current life events were directly associated with lethality of the self-harm act. The portfolio illustrates the issues inherent in the treatment and management of schizophrenia and the potential of CBT in addressing symptoms and sequelae of acute psychosis. Four case studies are presented.

Self-injury and eating pathology

It was found that Urgency and lack of Perseverance were significantly elevated in women with self-injury or eating pathology, and significantly higher again in women with both these syndromes. A longitudinal design found that self-injury tends to progress from milder, compulsive forms, to more severe, impulsive forms over time. The portfolio examines the frequent co-occurrence of substance use and psychiatric disorders (Dual Diagnosis). Four primary conceptualisations of how dual diagnoses develop and present are discussed. These models are then applied to inform four case studies.

The natural history of self-harm from adolescence to young adulthood : a population-based cohort study

Background Knowledge about the natural history of self-harm is scarce, especially during the transition from adolescence to young adulthood, a period characterised by a sharp rise in self-inflicted deaths. From a repeated measures cohort of a representative sample, we describe the course of self-harm from middle adolescence to young adulthood.

Methods A stratified, random sample of 1943 adolescents was recruited from 44 schools across the state of Victoria, Australia, between August, 1992, and January, 2008. We obtained data pertaining to self-harm from questionnaires and telephone interviews at seven waves of follow-up, commencing at mean age 15·9 years (SD 0·49) and ending at mean age 29·0 years (SD 0·59). Summary adolescent measures (waves three to six) were obtained for cannabis use, cigarette smoking, high-risk alcohol use, depression and anxiety, antisocial behaviour and parental separation or divorce.

Findings 1802 participants responded in the adolescent phase, with 149 (8%) reporting self-harm, More girls (95/947 [10%]) than boys (54/855 [6%]) reported self-harm (risk ratio 1·6, 95% CI 1·2–2·2). We recorded a substantial reduction in the frequency of self-harm during late adolescence. 122 of 1652 (7%) participants who reported self-harm during adolescence reported no further self-harm in young adulthood, with a stronger continuity in girls (13/888) than boys (1/764). During adolescence, incident self-harm was independently associated with symptoms of depression and anxiety (HR 3·7, 95% CI 2·4–5·9), antisocial behaviour (1·9, 1·1–3·4), high-risk alcohol use (2·1, 1·2–3·7), cannabis use (2·4, 1·4–4·4), and cigarette smoking (1·8, 1·0–3·1). Adolescent symptoms of depression and anxiety were clearly associated with incident self-harm in young adulthood (5·9, 2·2–16).

Interpretation Most self-harming behaviour in adolescents resolves spontaneously. The early detection and treatment of common mental disorders during adolescence might constitute an important and hitherto unrecognised component of suicide prevention in young adults.

Funding National Health and Medical Research Council, Australia, and operational infrastructure support programme, Government of Victoria, Australia.

Measuring self-care in chronic heart failure : a review of the psychometric properties of clinical instruments

Background : Improved self-care skills and behaviors are an important outcome of patient education and counseling. Both researchers and health professionals need to utilize instruments that are reliable and valid at measuring this outcome to advance our understanding as to the efficacy of clinical practice directed toward improving self-care.

Objective : The aim of this study was to identify instruments that measure chronic heart failure (CHF) self-care and demonstrate their psychometric properties.

Methods : A search of Medline, Cumulative Index to Nursing and Allied Health Literature, Medline, PsycArticles, Psychology and Behavioral Sciences Collection, and PsycINFO databases elucidated studies published between January 1980 and February 2009 that measure CHF self-care. The clinical instruments selected were disease-specific measures of CHF self-care behaviors that are promoted in best practice guidelines. Only instruments that reported estimates of reliability and validity were included in this review. Psychometric properties of the instruments were evaluated according to practice guidelines.

Results : The literature search identified 14 instruments published in peer-reviewed journals that measured constructs that predict or correlate to self-care rather than self-care itself. Only 2 disease-specific measures of self-care were identified (Self-care Heart Failure Index [SCHFI] and European Heart Failure Self-care Behavior Scale [EHFScBS]) that have undergone rigorous psychometric testing in CHF populations. Five aspects of validity had been demonstrated with EHFScBS, and 6 aspects of validity had been demonstrated with SCHFI. Two of 3 aspects of reliability have been demonstrated in both instruments.

Conclusion : Only 2 reliable and valid tools have been developed to specifically measure CHF self-care. Further use of these instruments in the research arena may reduce gaps in our understanding of CHF self-care and further shape clinical practice directed at improving it.

Coesão familiar associada à saúde bucal, fatores socioeconômicos e comportamentos em saúde

Pesquisas sobre saúde geral têm relacionado coesão familiar a fatores socioeconômicos e comportamentais. O objetivo deste estudo foi investigar a associação entre coesão familiar e fatores socioeconômicos, comportamentais e de saúde bucal. Este foi um estudo transversal com amostra por conglomerados em dois estágios. A amostra randomizada de 524 adolescentes era proveniente de escolas públicas da cidade de Piracicaba-SP. As variáveis foram avaliadas por questionários autoaplicáveis e os dados de saúde bucal, pelos índices CPO e CPI. A coesão familiar percebida pelo adolescente foi avaliada por meio da escala de adaptabilidade e coesão familiar. Análise univariada e regressão logística multinominal mostraram que adolescentes com baixa coesão familiar apresentaram mais chance de terem baixa renda (OR 2,28 IC95% 1,14-4,55), presença de cárie (OR 2,23 IC95% 1,21-4,09) e baixa frequência de escovação diária (OR 1,91 IC95% 1,03-3,54). Adolescentes com alta coesão familiar apresentaram mais chance que adolescentes com média coesão de terem alta renda e fator de proteção contra o hábito de tabagismo. Desta forma, a coesão familiar percebida pelo adolescente associou-se com variáveis comportamentais, socioeconômicas e de saúde bucal, indicando a importância de uma abordagem integral da saúde do paciente.

C 3-symmetric discotic liquid crystalline materials for molecular electronics: versatile synthesis and self-organization

This thesis presents the versatile synthesis and self-organization of C3-symmetric discotic nanographene molecules as well as their potential applications as materials in molecular electronics. The details can be described as follows: 1) A novel synthetic strategy towards properly designed C3 symmetric 1,3,5-tris-2’arylbenzene precursors has been developed. After the final planarization by treatment with FeCl3 under mild conditions, for the first time, it became possible to access a variety of new C3-symmetric hexa-peri-hexabenzocoronenes (HBCs) and a series of triangle-shaped nanographenes. D3 symmetric HBC with three alkyl substituents and C2 symmetric HBC with two alkyl substituents were synthesized and found to show the surprising decrease of isotropic points., the self-assembly at the liquid-solid interface displayed a unique zigzag and flower patterns. 2) Triangle-shaped discotics revealed a unique self-assembly behavior in solution, solid state as well as at the solution-substrate interface. A mesophase stability over the broad temperature range with helical supramoelcular arrangement were observed in the bulk state. The honeycomb pattern as the result of novel self-assembly was presented. Triangle-shaped discotics with swallow alkyl tails were fabricated into photovoltaic devices, the supramolecular arrangement upon thermal treatment was found to play a key role in the improvement of solar efficiency. 3) A novel class of C3 symmetric HBCs with alternating polar/apolar substituents was synthesized. Their peculiar self-assembly in solution, in the bulk and on the surface were investigated by NMR techniques, X-ray diffraction as well as different electron microscope techniques. 4) A novel concept for manipulating the intracolumnar stacking of discotics and thus for controlling the helical pitch was presented. A unique staggered stacking in the column was achieved for the first time. Theoretical simulations confirmed this self-organization and predicted that this packing should show the highest charge carrier mobility for all discotics.

Electrostatically self-assembled nanoparticles based on biomolecules

In this work, two different systems were investigated to develop fundamental understanding of the self-assembly behavior of polyelectrolytes and small organic counterions with a certain geometry. Complexes formed were characterized by light scattering in solution, as well as UV-Vis spectroscopy, analytical ultracentrifugation, gel electrophoresis, zeta potential and IR spectroscopy. The morphologies of the aggregates were observed by AFM in dried state on surface. The charge ratio, the valence and the structure of the counterion were shown to represent key parameters in the complexation. The influence of polyelectrolyte type and molecular weights was also determined for the structure formed.rnrnOne system was mainly focused on the association of double-strand DNA with non-intercalating divalent and tetravalent organic counterions. The other model system involved linear NaPSS and oligolysines. In addition, various influences on the morphology of the charged self-assembly complexes in AFM studies were discussed. It was shown that electrostatic self-assembly of DNA and non-intercalating counterions as well as of a linear synthetic polyelectrolyte with oligolysine counterions that can build mutual hydrogen bonds can yield supramolecular aggregates of a defined size. Various morphologies (flower-like, rod-like, toroidal and spherical) of the assemblies were obtained for different combinations of polyelectrolyte and counterions. Results presented in this work are of importance for the fundamental understanding of the association behavior of various polyelectrolytes and organic counterions. The selection of biopolymers for the study may give an opportunity to transfer the basic research results into biological applications, such as gene therapy or drug delivery.rn