An Actuarial Analysis of Calibration of Crop Insurance Premiums to Heterogeneous Risks

This paper examines whether the loadings on the crop insurance premium rates for risks such as moral hazard and adverse selection are adequate. From the discrete choice (tobit) analysis conducted, we discover that the premium loadings for 75% coverage level are not adequate, resulting in losses for the Risk Management Agency

Increased Matrix Metalloproteinase (MMPs) Levels Do Not Predict Disease Severity or Progression in Emphysema

Rationale: Though matrix metalloproteinases (MMPs) are critical in the pathogenesis of COPD, their utility as a disease biomarker remains uncertain. This study aimed to determine whether bronchoalveolar lavage (BALF) or plasma MMP measurements correlated with disease severity or functional decline in emphysema. Methods: Enzyme-linked immunosorbent assay and luminex assays measured MMP-1, -9, -12 and tissue inhibitor of matrix metalloproteinase-1 in the BALF and plasma of non-smokers, smokers with normal lung function and moderate-to-severe emphysema subjects. In the cohort of 101 emphysema subjects correlative analyses were done to determine if MMP or TIMP-1 levels were associated with key disease parameters or change in lung function over an 18-month time period. Main Results: Compared to non-smoking controls, MMP and TIMP-1 BALF levels were significantly elevated in the emphysema cohort. Though MMP-1 was elevated in both the normal smoker and emphysema groups, collagenase activity was only increased in the emphysema subjects. In contrast to BALF, plasma MMP-9 and TIMP-1 levels were actually decreased in the emphysema cohort compared to the control groups. Both in the BALF and plasma, MMP and TIMP-1 measurements in the emphysema subjects did not correlate with important disease parameters and were not predictive of subsequent functional decline. Conclusions: MMPs are altered in the BALF and plasma of emphysema; however, the changes in MMPs correlate poorly with parameters of disease intensity or progression. Though MMPs are pivotal in the pathogenesis of COPD, these findings suggest that measuring MMPs will have limited utility as a prognostic marker in this disease. © 2013 D'Armiento et al

A quadrafunctional electrocatalyst of nickel/nickel oxide embedded N-graphene for oxygen reduction, oxygen evolution, hydrogen evolution and hydrogen peroxide oxidation reactions

A multifunctional nano-heterostructured electrocatalyst of transition metal/metal oxide (nickel/nickel oxide) embedded on nitrogen-doped graphene is reported. The hybrid composite of N-doped graphene nanosheets with a high atomic percentage of nitrogen (8.2 at%) and embedded with highly distributed nickel/nickel oxide nanoparticles inside the graphene layers is synthesized by a one pot thermal annealing process. The resultant composite demonstrates excellent electrocatalytic activity utilizing the superior electrocatalytic properties of nickel/nickel oxide nanoparticles supported on nitrogen-doped graphene. The hybrid exhibits efficient oxygen reduction reaction (ORR) properties comparable with state-of-the-art electrode Pt/C with a four-electron transfer pathway and superior oxygen evolution reaction (OER) compared to the state-of-the-art electrode for the OER, Ru/C. Alternatively, this composite acts as an excellent electrode material for the hydrogen evolution reaction (HER) both in acidic and alkaline media. Nevertheless, this composite facilitates the hydrogen peroxide oxidation reaction (HPOR) in the presence of hydrogen peroxide, which is crucial for developing reversible fuel cells and fuel cells with liquid oxidant

Liquid-Crystal-Mediated 3D Macrostructured Composite of Co/Co3O4 Embedded in Graphene: Free-Standing Electrode for Efficient Water Splitting

A free-standing, 3D, macro/microstructured atomic-cobalt/cobalt-oxide-reduced-graphene-oxide (Co/Co3O4-Gr) composite has been developed for complete water splitting. The self-assembled porous morphology associated with the metal/metal oxide active sites makes the whole surface of the electrode conducive toward catalyzing hydrogen and oxygen evolution in alkaline media at a low onset potential. The liquid-crystal-mediated free-standing electrocatalyst shows oxygen evolution at the onset potential of 1.38 V and at the potential of 1.66 V for a current density of 10 mA cm−2. These potentials are comparable to the corresponding values for Ru/C (1.46 and 1.62 V, respectively). In addition, the promising hydrogen evolution performance of our composite compared to Pt/C in alkaline media makes it an efficient bifunctional electrocatalyst for comprehensive water splitting, as well as provides guidance for future electrochemical energy material technologies

Self-assembled N/S codoped flexible graphene paper for high performance energy storage and oxygen reduction reaction

A novel flexible three-dimensional (3D) architecture of nitrogen and sulfur codoped graphene has been successfully synthesized via thermal treatment of a liquid crystalline graphene oxide−doping agent composition, followed by a soft self-assembly approach. The high temperature process turns the layer-by-layer assembly into a high surface area macro- and nanoporous free-standing material with different atomic configurations of graphene. The interconnected 3D network exhibits excellent charge capacitive performance of 305 F g−1 (at 100 mV s−1), an unprecedented volumetric capacitance of 188 F cm−3 (at 1 A g−1), and outstanding energy density of 28.44 Wh kg−1 as well as cycle life of 10 000 cycles as a free-standing electrode for an aqueous electrolyte, symmetric supercapacitor device. Moreover, the resulting nitrogen/sulfur doped graphene architecture shows good electrocatalytic performance, long durability, and high selectivity when they are used as metal-free catalyst for the oxygen reduction reaction. This study demonstrates an efficient approach for the development of multifunctional as well as flexible 3D architectures for a series of heteroatom-doped graphene frameworks for modern energy storage as well as energy source applications

Three dimensional cellular architecture of sulfur doped graphene: self-standing electrode for flexible supercapacitors, lithium ion and sodium ion batteries

Tailoring the planar morphology of graphene and the generation of electron-dense active sites on its surface by heteroatom doping is one potential approach to enhance the charge storage performance of graphene based electrode materials. Herein, we have reported the preparation of a three-dimensional self-standing cellular architecture as sulfur-doped graphene foam (SGF) by using the simple self-assembly of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) polymer chains on graphene oxide followed by thermal treatment. Successful homogeneous sulfur doping in a three-dimensional (3D) framework of graphene allowed the material to have a large surface area with bulk electroactive regions on the surface for better interfacial contact with electrolyte ions and hence resulted in unprecedented energy storage capability in a flexible aqueous symmetric supercapacitor (367 F g-1 at 1 A g-1), a lithium ion battery (1697 mA h g-1 at 100 mA g-1), and a sodium ion battery (472 mA h g-1 at 50 mA g-1) as a binder-free electrode material. The outstanding electrochemical performance of the material demonstrates the potential of this synthesis approach for various heteroatom-doped self-standing nano-carbon monoliths on a small as well as a large scale for high-performance energy device fabrication for the advancement of modern electronic devices

Boron-functionalized graphene oxide-organic frameworks for highly efficient CO2 capture

The capture and storage of CO2 have been suggested as an effective strategy to reduce the global emissions of greenhouse gases. Hence, in recent years, many studies have been carried out to develop highly efficient materials for capturing CO2. Until today, different types of porous materials, such as zeolites, porous carbons, N/B-doped porous carbons or metal-organic frameworks (MOFs), have been studied for CO2 capture. Herein, the CO2 capture performance of new hybrid materials, graphene-organic frameworks (GOFs) is described. The GOFs were synthesized under mild conditions through a solvothermal process using graphene oxide (GO) as a starting material and benzene 1,4-diboronic acid as an organic linker. Interestingly, the obtained GOF shows a high surface area (506 m2 g−1) which is around 11 times higher than that of GO (46 m2 g−1), indicating that the organic modification on the GO surface is an effective way of preparing a porous structure using GO. Our synthetic approach is quite simple, facile, and fast, compared with many other approaches reported previously. The synthesized GOF exhibits a very large CO2 capacity of 4.95 mmol g−1 at 298 K (1 bar), which is higher those of other porous materials or carbon-based materials, along with an excellent CO2/N2 selectivity of 48.8

Nanoarchitectured Nitrogen-Doped Graphene/Carbon Nanotube as High Performance Electrodes for Solid State Supercapacitors, Capacitive Deionization, Li-Ion Battery, and Metal-Free Bifunctional Electrocatalysis

A three-dimensional nanostructured nitrogen-doped graphene/carbon nanotube composite has been synthesized via a thermal annealing process, using the high surface attachment properties of uric acid (solid nitrogen precursor) with graphene oxide and oxidized multiwalled carbon nanotube. In the synthesis procedures, the attachment of uric acid to graphene oxide surfaces and the oxidized multiwalled carbon nanotubes via hydrogen bonding and electrostatic forces in the solution leads to a lamellar nanostructure during thermal annealing by the proper insertion of carbon nanotubes in graphene layers with nitrogen doping. The resultant composite has good atomic percentage of N (11.2 at. %) and shows superior electrochemical energy storage and conversion properties compared with nitrogen-doped graphene only and physically mixed nitrogen-doped graphene and nitrogen-doped carbon nanotube samples. The composite exhibits high gravimetric and volumetric capacitance (324 F g -1 at a current density of 1 A g -1 ) as electrode in solid-state supercapacitors, superior capacitive deionization (440 F g -1 at a current density of 1 A g -1 ) in 1 M sodium chloride solution, and as high-performance anode in lithium-ion batteries (1150 mAh g -1 at 0.1 A g -1 ) with long-term cycling stability. In addition, the composite demonstrates efficient metal-free bifunctional electrocatalysis toward the oxygen reduction and evolution reactions, comparable with the commercial electrocatalysts