We present our achievement which is a ceramic plate phosphorable to produce white light when directly combined with commercially available blue light emitting diodes. The ceramic phase structure is that the Al₂O₃ particle is uniformly distributed in the Ce:YAG matrix. The Al₂O₃-Ce:YAG ceramic phosphor has a better luminous efficacy than the transparent Ce:YAG ceramic phosphor under the same test condition. The Al₂O₃ particle plays an important role in promoting the luminous efficacy. The Al₂O₃ particle changes the propagation of the light in ceramic, and it reduces the total internal reflection. That is why the composite phase ceramic phosphor improves extraction efficiency of light.

. 2002. A modeling approach to quantifying soil macroaggregate dynamics. Can. J. Soil Sci. 82: [181][182][183][184][185][186][187][188][189][190]. While several researchers have suggested that soil aggregate turnover is a significant control on organic matter dynamics, the quantification of soil aggregate dynamics has yet to be achieved. Quantification of soil aggregate turnover is essential to testing any hypothesis concerning the relationship between aggregate turnover and organic matter dynamics. The goal of the current work was to propose a modeling approach to the quantification of soil macroaggregate dynamics. The approach taken was to define model compartments representing water-stable soil aggregate size fractions and describing the flows between compartments using first-order kinetics. Soil aggregate data from a 2-yr field study on two contrasting soils were used to calibrate the model and yielded soil aggregate mean residence times ranging from 4 to 95 d, where aggregate dynamics were generally two to three times more rapid in a Gray Luvisol compared to a Black Chernozem. The model was subsequently used to predict the distribution of applied tracer spheres in water-stable aggregate size fractions from an initially free state. The models closely predicted the Dy "mean weight diameters" (Dy-MWD) after two growing seasons. While the models have several limitations, they offer the first attempt to quantitatively describe soil macroaggregate dynamics, which is essential to predicting the response in organic matter dynamics to changes in aggregate dynamics. [181][182][183][184][185][186][187][188][189][190]. Plusieurs chercheurs soutiennent que la rotation des agrégats dans le sol commande sensiblement la dynamique de la matière organique. Pourtant, nul n'a encore quantifié la dynamique des agrégats du sol. Avant de tester la moindre hypothèse sur les liens entre la rotation des agrégats et la dynamique de la matière organique, il importe de quantifier cette rotation. L'étude dont il est question ici avait pour but la création d'un modèle qui permettrait de quantifier la dynamique des macro-agrégats dans le sol. L'approche retenue consistait à paramétrer les compartiments du modèle correspondant aux fractions hydrostables d'agrégats d'une granulométrie donnée et à décrire les échanges entre ces compartiments par la cinétique au premier degré. Les auteurs se sont servis des données sur les agrégats recueillies lors d'une étude sur le terrain de deux ans, sur deux sols contrastants, pour étalonner leur modèle. Ils ont obtenu un temps de rétention moyen de 4 à 95 jours pour les agrégats, la dynamique des agrégats étant généralement 2 à 3 fois plus rapide dans le luvisol gris que dans le tchernoziom noir. Par la suite, ils ont utilisé le modèle pour prévoir la répartition de traceurs sphériques, de l'état libre aux fractions hydrostables de granulométrie donnée. Les modèles prédisent étroitement le rapport entre le Dy et le diamètre moyen pondéré après deux périodes végétatives. En dépit de leurs limites, ces m...

Pancreatic phospholipase A2 (phospholipase A2 group 1B, G1B) belongs to the superfamily of secreted phospholipase A2 (PLA2) enzymes. G1B has been proposed to be a potential target for diseases such as hypertension, obesity, and diabetes. Human pancreatic prophospholipase A2 (pro-hG1B) is activated by cleavage of the first seven-residue propeptide (phospholipase A2 propeptide, PROP). However, questions still remain on the mode of action for pro-hG1B. In this work, we expressed prohG1B in Pichia pastoris and determined the crystal structure at 1.55-Å resolution. The x-ray structure demonstrates that prohG1B forms a trimer. In addition, PROP occupies the catalytic cavity and can be self-cleaved at 37°C. A new membrane-bound surface and activation mechanism are proposed based on the trimeric model of pro-hG1B. We also propose a new autoproteolytic mechanism for pro-hG1B by the reaction triad Asp49-Arg0-Ser(-2) that is similar to the serine protease catalytic triad.Phospholipase A2 (PLA2, 5 EC 3.1.1.4) hydrolyzes glycerophospholipids at the sn-2 acyl bond to produce free fatty acids. The PLA2 family currently comprises five categories: the secreted PLA2s, the cytosolic PLA2s, the Ca 2ϩ -independent PLA2s, the platelet-activating factor acetyl hydrolases, and the lysosomal PLA2s. To date, based on the catalytic mechanism as well as functional and structural information, 15 different groups of PLA2 have been reported and named (1).G1B is a member of the secreted PLA2 enzymes. This lipolytic enzyme releases glycerophospholipids and arachidonic acid that serve as the precursors of signal molecules that mediate a multitude of biological functions, such as inflammation. The G1B gene has been reported to be linked to hypertension in three sample populations (2). The concentration of G1B protein in serum is a potential marker for pancreatic acinar cell carcinoma (3). Knock-out mice experiments showed that G1B knockdown can prevent diet-induced obesity and obesity-related insulin resistance (4). After being fed with glucose-rich meals, knock-out mice showed lower postprandial glycemia than wild-type mice (5). A recent report also pointed to the linkage between hG1B and ophthalmic diseases (6). Therefore, hG1B is considered to be a potential target for treatment of obesity, diabetes (4, 5), or ophthalmic diseases (6).Pro-hG1B is a digestive zymogen secreted from pancreatic acinar cells in its inactive form (7). It is activated by trypsin in the duodenum. The activation of pro-hG1B by cleavage of the PROP, a heptapeptide of the sequence DSGISPR, is linked to diseases like pancreatitis (8) and acute lung injury (9). Circulating hG1B, mostly in the form of pro-hG1B, indicates pancreatic injury in acute pancreatitis (10). PROP can be used in assays to characterize the severity of acute pancreatitis (11). The C-terminal pentapeptide of PROP (GISPR) is essential for the inhibition of enzyme activity (12). Besides trypsin, pro-hG1B can also be activated by thrombin (13) and 29-kDa trypsin-like endogenous type 1-proPLA2 activator (11)...

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