Reductively degradable polyester-based block copolymers prepared by facile polycondensation and ATRP: synthesis, degradation, and aqueous micellization

Well-defined reductively degradable amphiphilic block copolymers having disulfide linkages positioned repeatedly on hydrophobic chains, thus exhibiting fast degradation, were prepared by a combination of polycondensation and ATRP. The new method consists of three synthetic steps including, (1) polycondensation of commercially available diols and diacids through carbodiimide coupling or high temperature processes to synthesize degradable polyesters with disulfides labeled on the main chain at regular intervals (ssPES–OH), (2) bromination of ssPES–OH to ssPES–Br, and (3) ATRP for chain extension of ssPES–Br with water-soluble polymethacrylate, yielding ssPES-b-polymethacrylate block copolymers (ssABPs). The reductive cleavage of disulfide linkages in reducing conditions resulted in the degradation of ssPES homopolymers; their degradation rate was significantly enhanced with the increasing amounts of disulfide linkages in ssPES–OH and reducing agents. For ATRP, gel permeation chromatography and 1H-NMR results confirmed the synthesis of well-defined ssABPs and revealed that polymerizations were well controlled. Because of their amphiphilic nature, ssABPs self-assembled in water toward the formation of core/shell micelles consisting of a hydrophobic ssPES core surrounded with polymethacrylate coronas. The effects of the corona's chain length on thermal properties and micellization in water of well-defined ssABPs were examined. Moreover, reductive (or thiol-responsive) degradation of ssABP-based micelles enabled fast release of encapsulated model drugs. Cell culture experiments confirmed nontoxicity and biocompatibility of well-defined ssABPs as effect candidates for targeted delivery applications

The Functional Connectivity Landscape of the Human Brain

Functional brain networks emerge and dissipate over a primarily static anatomical foundation. The dynamic basis of these networks is inter-regional communication involving local and distal regions. It is assumed that inter-regional distances play a pivotal role in modulating network dynamics. Using three different neuroimaging modalities, 6 datasets were evaluated to determine whether experimental manipulations asymmetrically affect functional relationships based on the distance between brain regions in human participants. Contrary to previous assumptions, here we show that short- and long-range connections are equally likely to strengthen or weaken in response to task demands. Additionally, connections between homotopic areas are the most stable and less likely to change compared to any other type of connection. Our results point to a functional connectivity landscape characterized by fluid transitions between local specialization and global integration. This ability to mediate functional properties irrespective of spatial distance may engender a diverse repertoire of cognitive processes when faced with a dynamic environment.</p

Exploring academic and social adjustment of "Korean goose adolescents" in Canada

The purpose of this study is to explore the lived experiences of Korean "goose" adolescents who attempt to adjust themselves to academic and social environments in Canada. In this study, Korean goose adolescents are defined as those who come to English-speaking countries for a few years to seek out better learning opportunities; their fathers usually stay in Korea to earn money and provide economic support for their families, whereas the mothers take their children abroad to study (Choi, 2005b). Using an interpretive phenomenological analysis (IPA), the researcher conducted semi-structured and in-depth interviews with four Korean goose adolescents residing in Toronto. Findings revealed that these goose adolescents underwent significant adjustment difficulties. Despite their success in academic areas, they encountered various problems on a social level, due to both English language and cultural differences. However, they sought to develop adjustment strategies by obtaining practical assistance from co-ethnic groups: Korean churches and family members. They also attempted to change themselves into active, open-minded and independent learners. Although they still faced challenges and lacked sufficient support, they showed overall satisfaction with living and studying in Canada.Le propos de la présente étude est d'explorer l'expérience vécue d'adolescents coréens migrateurs (Korean goose adolescents) qui tentent de s'adapter à des environnements académique et social différents au Canada. Pour les fins de cette étude, les adolescents coréens migrateurs sont définis comme ceux qui effectuent des séjours de quelques années en des pays anglophones afin d'obtenir de meilleures opportunités d'apprentissage; le plus souvent, les pères de ces adolescents demeurent en Corée dans le but de mieux supporter financièrement leur famille, tandis que les mères accompagnent leur enfants à l'étranger (Choi, 2005b). Préconisant une analyse interprétative de type phénoménologique, la chercheuse a mené des entrevues semi-structurées et en profondeur auprès de quatre adolescents coréens migrateurs résidant à Toronto. Les résultats de l'étude montrent que ces adolescents, culturellement mal préparés, ont dû faire face à de multiples difficultés d'acculturation en sol canadien. Malgré leur succès académique, ces étudiants ont été confrontés à une série de problèmes relationnels avec leurs amis étrangers et ce, en raison de différences d'ordre culturel et linguistique (eu égard à l'usage de la langue anglaise). Pour résoudre ces difficultés, ils ont œuvré à développer des stratégies adaptatives en obtenant l'assistance pratique de membres de communautés ethniques davantage apparentées à la leur, d'églises coréennes et de leur famille. Ils ont également tenté de modifier leur propre attitude personnelle – devenant plus actifs, indépendants et ouverts d'esprit – afin de faciliter leur adaptation. Bien qu'étant toujours dans l'obligation de relever d'importants défis et souffrant d'un réel manque de soutien, ces étudiants éprouvent malgré tout, globalement, de la satisfaction à vivre et à étudier au Canada

국가 보건의료정보화의 정보전략계획(ISP) 수립 방안

22kc

Changes in Attentional Function in Patients From Before Through 12&nbsp;Months After Breast Cancer Surgery.

ContextAlthough approximately 75% of patients with breast cancer report changes in attentional function, little is known about how demographic, clinical, symptom, and psychosocial adjustment (e.g., coping) characteristics influence changes in the trajectories of attentional function over time.ObjectivesThis study evaluated interindividual variability in the trajectories of self-reported attentional function and determined which demographic, clinical, symptom, and psychosocial adjustment characteristics were associated with initial levels and with changes in attentional function from before through 12&nbsp;months after breast cancer surgery.MethodsBefore surgery, 396 women were enrolled. Attentional Function Index (AFI) was completed before and nine times within the first 12&nbsp;months after surgery. Hierarchical linear modeling was used to determine which characteristics were associated with initial levels and trajectories of attentional function.ResultsGiven an estimated preoperative AFI score of 6.53, for each additional month, the estimated linear rate of change in AFI score was an increase of 0.054 (P&nbsp;&lt;&nbsp;0.001). Higher levels of comorbidity, receipt of adjuvant chemotherapy, higher levels of trait anxiety, fatigue, and sleep disturbance, and lower levels of energy and less sense of control were associated with lower levels of attentional function before surgery. Patients who had less improvements in attentional function over time were nonwhite, did not have a lymph node biopsy, had received hormonal therapy, and had less difficulty coping with their disease.ConclusionFindings can be used to identify patients with breast cancer at higher risk for impaired self-reported cognitive function and to guide the prescription of more personalized interventions

Catalytic Activity of Ni_1-xLi_2xWO₄ Particles for Carbon Dioxide Photoreduction

This study introduces NiWO4 as a main photocatalyst, where the Ni component promotes methanation to generate a WO3-based catalyst, as a new type of catalyst that promotes the photoreduction of carbon dioxide by slowing the recombination of electrons and holes. The bandgap of NiWO4 is 2.74 eV, which was expected to improve the initial activity for the photoreduction of carbon dioxide. However, fast recombination between the holes and electrons was also expected. To overcome this problem, attempts were made to induce structural defects by partially replacing the Ni2+ ions in NiWO4 with Li+. The resulting CO2 conversion reaction was greatly enhanced with the Ni1-xLi2xWO4 catalysts containing Li+, compared to that of the pure NiWO4 catalysts. Notably, the total amount of CO and CH4 produced with the Ni0.8Li0.4WO4 catalyst was 411.6 nmol g&#8722;1. It is believed that the insertion of Li+ ions into the NiWO4 skeleton results in lattice defects due to charge and structural imbalance, which play a role in the capture of CO2 gas or excited electrons, thereby inhibiting recombination between the electrons and holes in the Ni1-xLi2xWO4 particles

Effect of Ce Doping of a Co/Al2O3 Catalyst on Hydrogen Production via Propane Steam Reforming

We synthesized cerium-doped cobalt-alumina (CoxCey/Al2O3) catalysts for the propane steam reforming (PSR) reaction. Adding cerium introduces oxygen vacancies, and the oxygen transfer capacity of the Ce promoter favors CO to CO2 conversion during PSR, inhibiting coke deposition and promoting hydrogen production. The best PSR activity was achieved at 700 &deg;C using the Co0.85Ce0.15/Al2O3 catalyst, which showed 100% propane (C3H8) conversion and about 75% H2 selectivity, and 6% CO, 5% CO2, and 4% CH4 were obtained. In contrast, the H2 selectivity of the base catalyst, Co/Al2O3, is 64%. The origin of the difference in activity was the lower C3H8 gas desorption temperature of the Co0.85Ce0.15/Al2O3 catalyst compared to that of the Co/Al2O3 catalyst; thus, the PSR occurred at low temperatures. Furthermore, more CO was adsorbed on the Co0.85Ce0.15/Al2O3 catalyst, and subsequently, desorbed as CO2. The activation energy for water desorption from the Co0.85Ce0.15/Al2O3 catalyst was 266.96 kJ/mol, higher than that from Co/Al2O3. Furthermore, the water introduced during the reaction probably reacted with CO on the Co0.85Ce0.15/Al2O3 catalyst, increasing CO2 generation. Finally, we propose a mechanism involving the Co0.85Ce0.15/Al2O3 catalyst, wherein propane is reformed on CoxCey sites, forming H2, and CO, followed by the conversion of CO to CO2 by water on CeO2 sites