Life time test in direct borohydride fuel cell system

The electric performances of direct borohydride fuel cells (DBFCs) are evaluated in terms of power density and life time with respect to the NaBH₄ concentration. A DBFC constituted of an anionic membrane, a 0.6 mg_Pt cm⁻² anode and a commercial non-platinum based cathode led to performances as high as 200 mW cm⁻² at room temperature and with natural convection of air. Electrochemical life time test at 0.55 mA cm⁻² with a 5 M NaBH₄/1 M NaOH solution shows a voltage diminution of 1 mV h⁻¹ and a drastic drop of performances after 250 h. The life time is twice longer with 2 M NaBH₄/1 M NaOH solution (450 h) and the voltage decrease is 0.5 mV h⁻¹. Analyses of the components after life time tests indicate that voltage loss is mainly due to the degradation of the cathode performance. Crystallisation of carbonate and borate is observed at the cathode side, although the anionic membrane displays low permeability to borohydride.     

Major depressive disorder is associated with attenuated cardiovascular reactivity and impaired recovery among those free of cardiovascular disease.

Objective: To examine cardiovascular reactivity and recovery to laboratory stress among a naturalistic sample of individuals diagnosed with major depressive disorder (MDD) and healthy control participants. Prospective evidence suggests that MDD confers risk for cardiovascular disease equal to or greater than the risk associated with depressed mood. Enhanced cardiovascular reactivity has been proposed as a mechanism explaining increased risk, but data are inconsistent as to whether depressed individuals exhibit enhanced or attenuated reactivity. Further, few studies have examined appraisal and recovery differences. Design: Participants diagnosed with MDD (N = 25) and healthy control participants (N = 25) engaged in a cardiovascular reactivity protocol including 2 tasks, each followed by a brief recovery period. Main outcome measures: Blood pressure, heart rate, pre-ejection period, cardiac output and total peripheral resistance were assessed. Appraisals of tasks were assessed prior to each task. Results: Depressed participants exhibited significantly less systolic blood pressure, heart rate, and cardiac output reactivity during speech, less heart rate reactivity during mirror tracing, and less heart rate recovery after speech and mirror tracing than controls. Depressed participants appraised the tasks as more demanding, threatening, and stressful and reported being less able to cope than controls. Appraisals were related to heart rate reactivity, but appraisals did not mediate the relationship between depression group and reactivity. Conclusion: Impaired recovery rather than exaggerated cardiovascular reactivity may partially explain the increased prospective cardiovascular disease risk in depressed individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strength in Numbers

David Salomon examines the history of the original World Trade Center (WTC) competition of 1962 and the more recent 2003 competition, finding interesting parallels in terms of how commercial and bureaucratic, as well as progressive, forces of innovation intersect over larger debates about control, power and questions of collaborative identity and practice within the city as a political machine, and which figure 9/11 in implicitly provocative ways. The 1962 competition featured another progressive architectural collaboration: Walter Gropius's The Architect's Collaborative (TAC). Not unlike the 2003 competition in which United Architects (UA) and other collaborative practices lost to the more stable, individual celebrity identity, TAC lost to Minoru Yamasaki. Salomon also argues that the organisational and structural qualities of UA's WTC proposal sought to embed collective operations of multiplicity rather than mere duplication of the previous WTC Twin Towers within the form of the design itself. Copyright © 2006 John Wiley & Sons, Ltd.     

Study of the Electrochemical Behavior of N-Substituted-4-Piperidones Curcumin Analogs: A Combined Experimental and Theoretical Approach

The electrochemical behavior of N-methyl- and N-benzyl-4-piperidone curcumin analogs were studied experimentally and theoretically. The studied compounds present different substituents at the para position in the phenyl rings (-H, -Br, -Cl, -CF₃, and -OCH₃). We assessed their electrochemical behavior by differential pulse and cyclic voltammetry, while we employed density functional theory (DFT) M06 and M06-2x functionals along with 6-311+G(d,p) basis set calculations to study them theoretically. The results showed that compounds suffer a two-electron irreversible oxidation in the range of 0.72 to 0.86 V, with surface concentrations ranging from 1.72 × 10⁻⁷ to 5.01 × 10⁻⁷ mol/cm². The results also suggested that the process is diffusion-controlled for all compounds. M06 DFT calculations showed a better performance than M06-2x to obtain oxidation potentials. We found a good correlation between the experimental and theoretical oxidation potential for N-benzyl-4-piperidones (R² = 0.9846), while the correlation was poor for N-methyl-4-piperidones (R² = 0.3786), suggesting that the latter suffer a more complex oxidation process. Calculations of the BDEs for labile C-H bonds in the compounds suggested that neither of the two series of compounds has a different tendency for a proton-coupled electron transfer (PCET) oxidation process. It is proposed that irreversible behavior is due to possible dimerization of the compounds by Shono-type oxidation.     

Preparation of high-T c oxide films via flaming solvent spray

Thick films of the high-temperature superconductors YBa₂Cu₃O_7?x and Bi_1.7Pb_0.3Sr₂Ca₂Cu₃O₁₀ have been prepared by spraying an ignited ethanol, ethylene glycol, or liquid ammonia solution of stoichiometric amounts of the metal nitrates (or acetates) onto polycrystalline MgO. The flaming spray is mechanically forced to traverse a region directly in front of the substrates. This new method is simple and inexpensive, and eliminates the problem of substrate cooling encountered in normal spray pyrolysis methods. Since decomposition of the solvent and metal salts occurs before deposition, the resulting films are relatively free of craters and nonuniformities common with spray methods. The method can be adapted to coat large areas and irregular or nonplanar shapes (i.e., cylinders), which could have useful magnetic shielding properties. The films were characterized by XRD and show single-phase material with preferredc-axis orientation. For YBa₂Cu₃O_7?x , resistance vs. temperature measurements show aT _c onset at 90 K and aT _c 0 at 76 K. Silver nitrate has been added to some of the solutions in an attempt to improve contact among individual grains.     

"After Me,The Deluge": Uncertainty and Water Policy in Israel

Israel's water system is characterized by a very high degree of uncertainty, emanating from the semi-arid climatic position, and the dynamic population growth.The agricultural sector dominates water policy making, thereby giving preference to the sector that consumes roughly 70% of the available resources. Water for agriculture is priced too low, resulting in its inefficient use. This paper seeks to explain water policy making in Israel, as an attempt to cope with uncertainty. We show that the pattern has been to shift the burden of uncertainty from present consumers to future consumers. This pattern is explained by the following factors: the high vulnerability of Israel's water system, due to uncertainty in both supply and demand; the inclination of elected policy makers to give preference to short-term objectives over long-term objectives; the acceptance of uncertainty as a constraint rather than a policy variable; and the acceptance of a given level of agricultural activity as a permanent constraint.     

Mutations of the RET-GDNF signaling pathway in Ondine''s curse

Sarcoidosis is a multi-systemic granulomatous disease of unknown cause. It commonly involves lymph nodes, lungs, eyes, and skin. Cardiac sarcoid may be isolated, or associated with systemic involvement. Cardiac involvement is found in 20-50% of autopsied patients with sarcoidosis. However, it only gives rise to clinical manifestations in about 5% of patients. Cardiac involvement by sarcoid has been reported to manifest as complete heart block, papillary muscle dysfunction, congestive heart failure, pericarditis and/or effusion, conduction abnormality or arrhythmia, chest pain, and sudden death. The most common site of involvement is the interventricular septum base, which when involved may lead to heart block or arrhythmia. We report a case of sudden death in a 33-year-old male with a history of surgically repaired congenital heart disease. Although his congenital heart disease was originally postulated to be important in his death, autopsy examination revealed cardiac sarcoid with prominent involvement of the conduction system.     

Levuglandin E2-protein adducts in human plasma and vasculature

The prostaglandin endoperoxide PGH2 rearranges nonenzymatically to generate prostaglandins and secoprostanoic acid levulinaldehyde derivatives such as PGE2 and levuglandin (LG) E2, respectively. Direct detection of LGE2 in biological samples is complicated because it is rapidly sequestered by covalent adduction to endogenous nucleophiles including proteins, which produces LGE2-derived protein-bound pyrroles. Therefore, to detect LGE2-protein adducts in vivo, antibodies were raised against a covalent adduct of LGE2 with keyhole limpet hemocyanin (KLH). This antigen enabled the production of high-titer antibodies that exhibit minimal cross-specificity and are sensitive for detecting LGE2-derived pyrroles. Although pyrrole yields are low at LG/protein ratios found in vivo, an enzyme-linked immunosorbent assay with the LGE2-KLH antibodies detects LGE2-derived protein-bound pyrrole immunoreactivity in human plasma from specific patient populations. Furthermore, prominent immunocytochemical staining of human brain thin sections revealed the presence of LGE2-derived pyrrole immunoreactivity, especially in the meningeal vessels of some patients. This demonstration of LG-protein adducts in human plasma and vasculature provides the first evidence for the biological occurrence of levuglandins in vivo and further suggests that these antibodies might prove useful in diagnostic and mechanistic studies of various disease conditions.