Parameterization of below-cloud scavenging for polydisperse fine mode aerosols as a function of rain intensity.

The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere. Due to its complexity and dependence on both aerosol and raindrop sizes, wet scavenging process has been poorly treated, especially during the removal of fine particles. This makes the numerical simulation of below-cloud scavenging in large-scale aerosol models unrealistic. To consider the slip effects of submicron particles, a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor. The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles. The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation. Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268, the coefficient of a and b in Λm = aRb spread in the range of 0.0002- 0.1959 for a and 0.3261- 0.525 for b over a size distribution of GSD of 1.3-2.5 and a geometric mean diameter of 0.01- 2.5 µm. Overall, this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity. This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity. Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.

Ceramic-Based Composite Solid Electrolyte for Lithium-Ion Batteries.

Solid-state electrolytes such as lithium ion conducting ceramic or solid polymers have been studied as substitutes for liquid electrolytes, but critical problems exist at the interfacial resistance between the solid electrode and the solid electrolyte. In this study, we combined 80 wt % Li1.3 Ti1.7 Al0.3 (PO4 )3 (LTAP) as a lithium ion conducting ceramic with 10 wt % of poly(vinylidene fluoride) (PVdF) as a binder, and 10 wt % 1 M LiPF6 in ethyl carbonate/dimethyl carbonate (EC/DMC) to develop a new composite electrolyte. The ceramic-based composite electrolyte showed thermal stability and high ionic conductivity through reduction of the interface resistance. The lithium ion conductivity of the composite electrolyte was 8.9×10-4  S cm-1 at room temperature without leakage. Electrochemical tests of the Li1+x Mn2 O4 -LTAP-based composite electrolyte-Li1-x Mn2 O4 cell showed that the composite could be utilized as a potential electrolyte for high-safety lithium-ion batteries.

Thermal decomposition and recovery behaviors of layered gadolinium hydroxychloride.

The thermal behavior of gadolinium hydroxychloride (Gd(2)(OH)(5)Cl·nH(2)O, LGdH) has been closely studied to provide the important factors that should be considered for its high temperature applications. Combined analyses of thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) showed that, under atmospheric air with a considerable amount of water, the decomposition of LGdH to Gd(2)O(3) is completed at 1050 °C. However, in either dry air or Ar gas, the transformation continued up to around 1300 °C. Thus, the thermal decomposition of LGdH was more influenced by H(2)O than by O(2). FT-IR spectra and X-ray diffraction (XRD) patterns were used to study LGdHs calcined at high temperatures (up to at least 600 °C). Calcined LGdH's ability to intercalate anions into the interlayer space could be recovered by the reconstruction of intralayer structure through rehydration and rehydroxylation. These processes were significantly accelerated at elevated temperatures. The recovery behavior of LGdH was examined in different anionic solutions at different temperatures.

The mixed-valent titanium phosphate, Li(2)Ti(2)(PO(4))(3), dilithium dititanium(III/IV) tris-(orthophosphate).

The mixed-valent titanium phosphate, Li(2)Ti(2)(PO(4))(3), has been prepared by the reactive halide flux method. The title compound is isostructural with Li(2)TiM(PO(4))(3) (M = Fe, Cr) and Li(2)FeZr(PO(4))(3) and has the same (3) (∞)[Ti(2)(PO(4))(3)](2-) framework as the previously reported Li(3-) (x)M(2)(PO(4))(3) phases. The framework is built up from corner-sharing TiO(6) octa-hedra and PO(4) tetra-hedra, one of which has 2 symmetry. The Li(+) ions are located on one crystallographic position and reside in the vacancies of the framework. They are surrounded by four O atoms in a distorted tetra-hedral coordination. The classical charge-balance of the title compound can be represented as Li(+) (2)(Ti(3+)/Ti(4+))(PO(4) (3-))(3).

The significance of perfusion defect at myocardial perfusion MR imaging in a cat model of acute reperfused myocardial infarction.

OBJECTIVE: To determine whether the size of a perfusion defect seen at myocardial perfusion MR imaging represents the extent of irreversibly damaged myocardium in acute reperfused myocardial infarction. MATERIALS AND METHODS: In nine cats, reperfused myocardial infarction was induced by occlusion of the left anterior descending coronary artery for 90 minutes and subsequent reperfusion for 90 minutes. At single-slice myocardial perfusion MR imaging at the midventricular level using a turbo-FLASH sequence, 60 short-axis images were sequentially obtained with every heart beat after bolus injection of gadomer-17. The size of the perfusion defect was measured and compared with both the corresponding unstained area seen at triphenyl tetrazolium chloride (TTC) staining and the hyperenhanced area seen at gadophrin-2- enhanced MR imaging performed in the same cat six hours after myocardial perfusion MR imaging. RESULTS: The sizes of perfusion defects seen at gadomer-17-enhanced perfusion MR imaging, unstained areas at TTC staining, and hyperenhanced areas at gadophrin-2-enhanced MR imaging were 20.4+/-4.3%, 29.0+/-9.7%, and 30.7+/- 10.6% of the left ventricular myocardium, respectively. The perfusion defects seen at myocardial perfusion MR imaging were significantly smaller than the unstained areas at TTC staining and hyperenhanced areas at gadophrin-2- enhanced MR imaging (p < .01). The sizes of both the perfusion defect at myocardial perfusion MR imaging and the hyperenhanced area at gadophrin-2- enhanced MR imaging correlated well with the sizes of unstained areas at TTC staining (r = .64, p = .062 and r = .70, p = .035, respectively). CONCLUSION: In this cat model, the perfusion defect revealed by myocardial perfusion MR imaging underestimated the true size of acute reperfused myocardial infarction. The defect may represent a more severely damaged area of infarction and probably has prognostic significance.