▪ Abstract  The past 10 years have witnessed a tremendous acceleration in research devoted to non-fluorinated polymer membranes, both as competitive alternatives to commercial perfluorosulfonic acid membranes operating in the same temperature range and with the objective of extending the range of operation of polymer fuel cells toward those more generally occupied by phosphoric acid fuel cells. Important requirements are adequate membrane mechanical strength at levels of functionalization (generally sulfonation) and hydration allowing high proton conductivity, and stability in the aggressive environment of a working fuel cell, in particular thermohydrolytic and chemical stability. This review provides an overview of progress made in the development of proton-conducting hydrocarbon and heterocyclic-based polymers for proton exchange and direct methanol fuel cells and describes the various approaches made to polymer modification/synthesis and salient properties of the materials formed, including those relating to proton transport and proton conductivity, e.g., water diffusion and electro-osmotic drag. The microstructure, deduced from small angle X-ray and neutron diffraction measurements of representative non-fluorinated polymers is compared with that of perfluorosulfonic acid membranes. Different degradation mechanisms and aging processes that can result in chemical and morphological alteration are considered, and recent characterization of membrane-electrode assemblies (MEAs) in direct methanol and hydrogen-air (oxygen) fuel cells completes this review of the state of the art. While several types of non-fluorinated polymer membrane have demonstrated lifetimes of 500–4000 h, only a limited number of systems exist that hold promise for long-term operation above 100°C. 1

Research emanating from the field of developmental science indicates that initial risk factors for substance use disorder can be evident in early childhood. One dominant developmental pathway connecting these initial risk factors with subsequent substance use disorders focuses on the central role of disinhibited or externalizing behaviors. In the current paper, we delineate a second pathway that focuses on problems with emotion regulation associated with internalizing symptomatology. Several studies indicate that internalizing symptoms in early and middle childhood predict substance involvement in adolescents and young adulthood. We describe a risk model that traces the potential developmental markers of this internalizing pathway to substance use disorders and that identifies a population potentially vulnerable to this risk process, namely children of alcoholic parents. We consider the relation between the internalizing pathway and the more widely researched externalizing pathway. We then conclude with a discussion of the implications of this model for prevention efforts. In this manner, we strive for a translational goal, linking our existing understanding of internalizing processes and substance use disorders with our efforts to develop effective prevention programs.

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Background Ventilator-associated pneumonia is associated with increased morbidity and mortality. Objective To examine the effects of mechanical (toothbrushing), pharmacological (topical oral chlorhexidine), and combination (toothbrushing plus chlorhexidine) oral care on the development of ventilator-associated pneumonia in critically ill patients receiving mechanical ventilation. Methods Critically ill adults in 3 intensive care units were enrolled within 24 hours of intubation in a randomized controlled clinical trial with a 2 × 2 factorial design. Patients with a clinical diagnosis of pneumonia at the time of intubation and edentulous patients were excluded. Patients (n = 547) were randomly assigned to 1 of 4 treatments: 0.12% solution chlorhexidine oral swab twice daily, toothbrushing thrice daily, both toothbrushing and chlorhexidine, or control (usual care). Ventilator-associated pneumonia was determined by using the Clinical Pulmonary Infection Score (CPIS). Results The 4 groups did not differ significantly in clinical characteristics. At day 3 analysis, 249 patients remained in the study. Among patients without pneumonia at baseline, pneumonia developed in 24% (CPIS ≥6) by day 3 in those treated with chlorhexidine. When data on all patients were analyzed together, mixed models analysis indicated no effect of either chlorhexidine (P = .29) or toothbrushing (P = .95). However, chlorhexidine significantly reduced the incidence of pneumonia on day 3 (CPIS ≥6) among patients who had CPIS <6 at baseline (P = .006). Toothbrushing had no effect on CPIS and did not enhance the effect of chlorhexidine. Conclusions Chlorhexidine, but not toothbrushing, reduced early ventilator-associated pneumonia in patients without pneumonia at baseline.

Establishing new reactivity map descriptor of TOF–SD for PGM-free Fe–N–C catalysts ORR activity.

This article provides a comprehensive perspective of perfluorosulfonic acid fuel cell membrane degradation phenomena, reviews and appraises the effectiveness of key concepts for the mitigation strategies and identifies future research priorities.

When complexed with a strong inorganic acid such as sulfuric or phosphoric acid, ®lms of polybenzimidazole (PBI) show two types of behaviour, depending on the time of immersion in the corresponding acid bath. The ®rst type, prepared at shorter doping times, has conductivity in the range 10 25 ±10 24 S cm 21 , whilst the second, of conductivity w10 23 S cm 21 is formed after more prolonged immersion. The `switch-over' from one state to the other is at 10±11 h in H 3 PO 4 , and 2±3 h in H 2 SO 4 . PBI has a remarkable capacity to concentrate H 3 PO 4 and, even in an acid bath of concentration 3 mol dm 23 , the acid concentration within a PBI membrane is ca. 14.5 mol dm 23 . IR spectroscopy performed on hydrated PBI membranes as a function of temperature, and on acid-complexed membranes as a function of the amount of sorbed acid con®rms proton transfer from H 3 PO 4 to the imino groups of PBI and, at high doping levels, the presence of undissociated H 3 PO 4 .

Clinical research on African American single mother families has focused largely on mother-child dyads, with relatively less empirical attention to the roles of other adults or family members who often assist with childrearing. This narrow definition of "family" fails to take into account the extended family networks which often provide support for African American single mother families and the influence of these other adults on maternal parenting and youth adjustment. Our review integrates the literature on the role of extended family members, highlights the strengths and limitations of this work, and proposes the use of theory and methods from the coparenting literature to guide future study in this area. The relevance of the study of coparenting for family-based intervention efforts targeting African American youth from single mother homes is addressed.