Pillar structured membranes were fabricated to examine their effect on the performance of polymer electrolyte membrane fuel cells (PEMFCs) at elevated temperature and low relative humidity (RH). A surface of the membrane possessed ordered micropillar arrays patterned by the imprint/micromold lithography. Three pillar structured membranes prepared had the same feature width and pitch of 7.0 and 14.2μm , respectively, but different heights of 3.4, 6.7, and 10.0μm . In membrane electrode assemblies (MEAs) made from the membranes, the pillars were extending toward the gas diffusion layer in the cathode catalyst layer with an average thickness of 12μm . The I–V characteristics for the MEAs at 90°C and 35% RH were improved with increasing pillar height. The MEAs with the pillar heights of 6.7 and 10.0μm outperformed a conventional one with a flat membrane, while the MEA with the pillar height of 3.4μm underperformed the conventional one. Tafel slopes and oxygen gain analysis indicated that the improvement in the MEA performance was mainly due to the suppression of the cathodic concentration overvoltage. Numerical simulations proved that the pillars promoted the reactant transport to the catalyst far from the membrane/catalyst interface which was rarely contributed to the oxygen reduction in the conventional MEA.

Despite evidence of a relationship among obstructive sleep apnea (OSA), metabolic dysregulation, and diabetes, it is uncertain whether OSA treatment can improve metabolic parameters. We sought to determine effects of long-term continuous positive airway pressure (CPAP) treatment on glycemic control and diabetes risk in patients with cardiovascular disease (CVD) and OSA. RESEARCH DESIGN AND METHODSBlood, medical history, and personal data were collected in a substudy of 888 participants in the Sleep Apnea cardioVascular Endpoints (SAVE) trial in which patients with OSA and stable CVD were randomized to receive CPAP plus usual care, or usual care alone. Serum glucose and glycated hemoglobin A 1c (HbA 1c ) were measured at baseline, 6 months, and 2 and 4 years and incident diabetes diagnoses recorded. RESULTSMedian follow-up was 4.3 years. In those with preexisting diabetes (n 5 274), there was no significant difference between the CPAP and usual care groups in serum glucose, HbA 1c , or antidiabetic medications during follow-up. There were also no significant between-group differences in participants with prediabetes (n 5 452) or new diagnoses of diabetes. Interaction testing suggested that women with diabetes did poorly in the usual care group, while their counterparts on CPAP therapy remained stable. CONCLUSIONSAmong patients with established CVD and OSA, we found no evidence that CPAP therapy over several years affects glycemic control in those with diabetes or prediabetes or diabetes risk over standard-of-care treatment. The potential differential effect according to sex deserves further investigation.Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper-airway collapse during sleep that causes intermittent hypoxemia, sleep fragmentation, and daytime sleepiness. The standard therapy for OSA is continuous positive airway pressure (CPAP) to prevent airway obstruction (1).OSA is common in the population and strongly associated with obesity (2). Prospective cohort studies have found associations between moderate to severe OSA and

Warfarin was found to be more efficacious than aspirin for an anticoagulation therapy of older Chinese patients with AF and stable coronary heart disease.

Machined feature quality is examined, and the effects of laser pulse width (and thus peak power or intensity) are investigated for the following four laser systems: (1) a millisecond-class, free-running Nd:YAG; (2) a 100-nanosecond-class, Q-switched Nd:YAG laser; (3) a 100-picosecond-class, mode locked Nd:YAG laser; and (4) a 100-femtosecond-class, Ti:sapphire chirped pulse amplification laser. The effect of shorter laser wavelength is also examined by using the second harmonic wavelength of the Nd:YAG laser in the Q-switched and the mode locked pulse formats. Hole drilling and cutting of superalloy, ceramic, and composite materials are studied. The machined feature quality is improved as the pulse width becomes shorter and the peak intensity becomes higher. The shorter wavelength provides another significant improvement. Finally, an attempt is made to view these quality improvements in the context of process throughput and cost of ownership.

Abstract