Modeling All-sky Global Solar Radiation Using MODIS Atmospheric Products: A Case Study in Qinghai-Tibet Plateau

The surface solar radiation (SSR) is of great importance to bio-chemical cycle and life activities. However, it is impossible to observe SSR directly over large areas especially for rugged surfaces such as the Qinghai-Tibet Plateau. This paper presented an improved parameterized model for predicting all-sky global solar radiation on rugged surfaces using Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric products and Digital Elevation Model (DEM). The global solar radiation was validated using 11 observations within the plateau. The correlation coefficients of daily data vary between 0.67-0.86, while those of the averages of 10-day data are between 0.79-0.97. The model indicates that the attenuation of SSR is mainly caused by cloud under cloudy sky, and terrain is an important factor influencing SSR over rugged surfaces under clear sky. A positive relationship can also be inferred between the SSR and slope. Compared with horizontal surfaces, the south-facing slope receives more radiation, followed by the west- and east-facing slopes with less SSR, and the SSR of the north-facing slope is the least.

All-organic tunnel junctions as connecting units in tandem organic solar cell

We employed organic heterojunction films as all-organic connecting units to fabricate tandem organic photovoltaic cells by continuous deposition. The all-organic connecting units with a better transparence and a lower sublimation temperature became an effective recombination center for electrons and holes photogenerated in front cell and back cell, respectively. Tunnel mechanism was proposed to explain the combination of photogenerated carrier.

Ionic liquid-based "all-in-one" synthesis and photoluminescence properties of lanthanide fluorides

A facile route to the synthesis of LnF(3) nanocrystals has been accomplished in three ionic liquids (ILs) (OmimPF(6), OmimBF(4), and BmimPF(6)). The partial hydrolysis of PF6- and BF4- was utilized to introduce a new fluoride source. Uniform LnF(3) (Ln = La, Ce, Pr, Nd, Sm, Eu, Er), Tb3+-doped CeF3, and Eu3+-doped LaF3 nanocrystals could be obtained in a large scale, and the products were up to 0.15 g per 10 mL solvents. In the "all-in-one" systems, the ILs acted as solvents, reaction agents, and templates.

Ionic liquid-based "all-in-one" synthesis and photoluminescence properties of lanthanide fluorides

A facile route to the synthesis of LnF(3) nanocrystals has been accomplished in three ionic liquids (ILs) (OmimPF(6), OmimBF(4), and BmimPF(6)). The partial hydrolysis of PF6- and BF4- was utilized to introduce a new fluoride source. Uniform LnF(3) (Ln = La, Ce, Pr, Nd, Sm, Eu, Er), Tb3+-doped CeF3, and Eu3+-doped LaF3 nanocrystals could be obtained in a large scale, and the products were up to 0.15 g per 10 mL solvents. In the "all-in-one" systems, the ILs acted as solvents, reaction agents, and templates.

Synthesis and characterization of phenylene-thiophene all-conjugated diblock copolymers

Grignard metathesis (GRIM) polymerization for all-conjugated diblock copolymers comprising poly (2,5-dihexyloxy-1,4-phenylene) (PPP) and poly(3-hexylthiophene) (P3HT) blocks were systematically studied with LiCl as additive and 1,2-bis (diphenylphosphino) ethane nickel dichloride (Ni(dppe)Cl-2) or 1,3-bis(diphenylphosphino) propane nickel dichloride (Ni(dppp)Cl-2) as catalyst. It was found that the addition order of the monomers was crucial for the success of copolymerization. With the monomer addition in the order of phenyl and then thienyl Grignard reagents, all-conjugated PPP-b-P3HT diblock copolymers with different block ratios were successfully synthesized. In contrast, the inverted addition order only afforded a mixture containing both block copolymers and deactivated or end-capped homopolymers.

Temperature dependence of the distribution of the first passage time: Results from discontinuous molecular dynamics simulations of an all-atom model of the second beta-hairpin fragment of protein G

More than 22 000 folding kinetic simulations were performed to study the temperature dependence of the distribution of first passage time (FPT) for the folding of an all-atom Go-like model of the second beta-hairpin fragment of protein G. We find that the mean FPT (MFPT) for folding has a U (or V)-shaped dependence on the temperature with a minimum at a characteristic optimal folding temperature T-opt*. The optimal folding temperature T-opt* is located between the thermodynamic folding transition temperature and the solidification temperature based on the Lindemann criterion for the solid. Both the T-opt* and the MFPT decrease when the energy bias gap against nonnative contacts increases. The high-order moments are nearly constant when the temperature is higher than T-opt* and start to diverge when the temperature is lower than T-opt*. The distribution of FPT is close to a log-normal-like distribution at T* greater than or equal to T-opt*. At even lower temperatures, the distribution starts to develop long power-law-like tails, indicating the non-self-averaging intermittent behavior of the folding dynamics. It is demonstrated that the distribution of FPT can also be calculated reliably from the derivative of the fraction not folded (or fraction folded), a measurable quantity by routine ensemble-averaged experimental techniques at dilute protein concentrations.

Isothermal and nonisothermal crystallization of poly(aryl ether ketone ketone) with all-para phenylene linkage

Isothermal and nonisothermal crystallization behavior for PEKK(T) was studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron diffraction (ED). In the isothermal crystallization process, the Avrami parameters obtained were n = 2.33-2.69, which shows crystal growth of two-dimensional extensions consistent with our observations by TEM. The lamellar thickness increases with the crystallization temperature of PEKK(T) crystallized isothermally from the melt. However, for the nonisothermal crystallization of PEKK(T), the results from the modified Avrami analysis show two different crystallization processes. Avrami exponents n(1) = 3.61-5.30, obtained from the primary crystallization process, are much bigger than are the secondary n(2) = 2.26-3.04 and confirmed by the observation of the spherulite morphology. PEKK(T) crystallized isothermally from the melt possesses the same crystal structure (Form I) as that from nonisothermal melt crystallization. The results from TEM observation show that the spherulite radius decreases with an increasing cooling rate. (C) 2001 John Wiley & Sons, Inc.

Computer perception of topological symmetry by all-paths algorithm

During the development of our ESESOC system (Expert System for the Elucidation of the Structures of Organic Compounds), computer perception of topological symmetry is essential in searching for the canonical description of a molecular structure, removing the irredundant connections in the structure generation process, and specifying the number of peaks in C-13- and H-1-NMR spectra in the structure evaluation process. In the present paper, a new path identifier is introduced and an algorithm for detection of topological symmetry from a connection table is developed by the all-paths method. (C) 1999 Elsevier Science B.V. All rights reserved.

Developing molecular identification numbers by an all-paths method

A new topological index is devised from an all-paths method. This molecular topological index has highly discriminating power for various kinds of organic compounds such as alkane trees, complex cyclic or polycyclic graphs, and structures containing heteroatoms and thus can be used as a Molecular IDentification number (MID) for chemical documentation. Some published MIDs derived from an all-paths method and their structural selectivity for alkane trees are also reviewed.

HIGH-TEMPERATURE SUPERCONDUCTOR, YBA2CU3O7-X AS ALL-SOLID-STATE LITHIUM CELL

The utility of the high-temperature superconductor, YBa2Cu3O7-x as the cathode material for an all-solid-state lithium cell has been examined. The capacity of YBa2Cu3O7-x is 223 mA h g-1 and the discharge efficiency is > 92%. Measurements of a.c. impedance show that the charge-transfer resistance at the interface of the electrolyte/cathode is very low and increases with the depth-of-discharge of the battery. Studies using X-ray photoelectron spectroscopy (XPS) reveal that the cathode becomes doped with Li+ ions as the cell discharges.

AN ALL-SOLID-STATE LITHIUM POLYANILINE RECHARGEABLE CELL

The performance of an all-solid-state cell having a lithium negative electrode, a modified polyethylene oxide (PEO)-epoxy resin (ER) electrolyte, and a polyaniline (PAn) positive electrode has been studied using cyclic voltammetry, charge/discharge cycling, and polarization curves at various temperatures. The redox reaction of the PAn electrode at the PAn/modifed PEO-ER interface exhibits good reversibility. At 50-80-degrees-C, the Li/PEO-ER-LiClO4/PAn cell shows more than 40 charge/discharge cycles, 90% charge/discharge efficiency, and 54 W h kg-1 discharge energy density (on PAn weight basis) at 50-mu-A between 2 and 4 V. The polarization performance of the battery improves steadily with increase in temperature.

Mirando al futuro: conexión directa con la investigación biomédica

Los estudios de Ciencias Biomédicas tienen una fuerte carga experimental y conexión con el mundo de la investigación que a muchos alumnos les cuesta reconocer, especialmente entre los de primer curso. Por ello, los autores hemos diseñado una actividad práctica integrada y evaluable para la asignatura Bioquímica II del Grado de Medicina, impartida en primer curso. Se pretendía conectar la asignatura con el mundo profesional de la investigación en Ciencias Biomédicas. El trabajo de los alumnos consistió en buscar la máxima información sobre el grupo que les hubiera correspondido, preparar una entrevista para realizar al investigador responsable del laboratorio y analizar su publicación más relevante, centrándose en la parte de su investigación que tiene que ver con nuestros estudios. El resultado ha sido satisfactorio a todos los niveles: los alumnos han obtenido buenas calificaciones y han valorado la actividad con un 3 sobre 4, los investigadores puntuaron mayoritariamente con la máxima calificación a los alumnos y los profesores estamos satisfechos con el aprovechamiento de los alumnos así como con la interacción con los investigadores y la integración con el resto de nuestros compañeros docentes. Entendemos que la actividad debe mejorarse de cara al futuro, sobre todo en relación al ítem peor valorado por los alumnos: la conexión entre lo explicado en clase y lo aprendido en el laboratorio.

Centenarians and their hearts: a prospective registry with comprehensive geriatric assessment, electrocardiogram, echocardiography, and follow-up

Background Data on the cardiac characteristics of centenarians are scarce. Our aim was to describe electrocardiogram (ECG) and echocardiography in a cohort of centenarians and to correlate them with clinical data. Methods We used prospective multicenter registry of 118 centenarians (28 men) with a mean age of 101.5 ± 1.7 years. Electrocardiogram was performed in 103 subjects (87.3%) and echocardiography in 100 (84.7%). All subjects underwent a follow-up for at least 6 months. Results Centenarians with abnormal ECG were less frequently females (72% vs 93%), had higher rates of previous consumption of tobacco (14% vs 0) and alcohol (24% vs 12%), and scored lower in the perception of health status (6.8 ± 2.0 vs 8.3 ± 6.8). Centenarians with significant abnormalities in echocardiography were less frequently able to walk 6 m (33% vs 54%). Atrial fibrillation/flutter was found in 27 subjects (26%). Mean left ventricular (LV) ejection fraction was 60.0 ± 10.5%. Moderate or severe aortic valve stenosis was found in 16%, mitral valve regurgitation in 15%, and aortic valve regurgitation in 13%. Diastolic dysfunction was assessed in 79 subjects and was present in 55 (69.6%). Katz index and LV dilation were independently associated with the ability to walk 6 m. Age, Charlson and Katz indexes, and the presence of significant abnormalities in echocardiography were associated with mortality. Conclusions Centenarians have frequent ECG alterations and abnormalities in echocardiography. More than one fifth has atrial fibrillation, and most have diastolic dysfunction. Left ventricular dilation was associated with the ability to walk 6 m. Significant abnormalities in echocardiography were associated with mortality.