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RNA synthesis in fully-grown mouse oocytes   总被引:1,自引:0,他引:1  
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Lignin is currently one of the most promising biologically derived resources, due to its abundance and application in biofuels, materials and conversion to value aromatic chemicals. The need to better characterize and understand this complex biopolymer has led to the development of many different analytical approaches, several of which involve mass spectrometry and subsequent data analysis. This review surveys the most important analytical methods for lignin involving mass spectrometry, first looking at methods involving gas chromatography, liquid chromatography and then continuing with more contemporary methods such as matrix assisted laser desorption ionization and time-of-flight-secondary ion mass spectrometry. Following that will be techniques that directly ionize lignin mixtures—without chromatographic separation—using softer atmospheric ionization techniques that leave the lignin oligomers intact. Finally, ultra-high resolution mass analyzers such as FT-ICR have enabled lignin analysis without major sample preparation and chromatography steps. Concurrent with an increase in the resolution of mass spectrometers, there have been a wealth of complementary data analyses and visualization methods that have allowed researchers to probe deeper into the “lignome” than ever before. These approaches extract trends such as compound series and even important analytical information about lignin substructures without performing lignin degradation either chemically or during MS analysis. These innovative methods are paving the way for a more comprehensive understanding of this important biopolymer, as we seek more sustainable solutions for our human species’ energy and materials needs.  相似文献   
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RANTES and related molecules, constitute the C-C class of chemokine supergene family and a group of cytokines produced by hematopoietic cells constitute the MCP-1 or C-X-C class. The roles of most of these chemokines are not well known, although members of the C-X-C family are inflammatory agents. Here, we report that intradermal injection of RANTES 10 ng/50 microL subcutaneously in the abdominal skin produced a strong inflammatory reaction, as evidenced by Evans blue dye, greater than FMLP (10(-6) mol/L) (approximately 57%); while MCP-1, 10 ng/50 microL was less effective than FMLP (10(-6) mol/L) (approximately 54%). Moreover, the histologic analysis of the cells stained with Toluidine blue (0.1%) were analyzed at a magnification of x40). RANTES 10 ng/50 microL and LPS produced higher numbers (142 +/- 11 and 193 +/- 21 of cells/200 mm2, respectively) of basophilic cell accumulation in the skin injection sites compared with FMLP (10(-6) mol/L) (127 +/- 14/200 mm2), while MCP-1 10 ng/50 microL was less effective (88 +/- 10/200 mm2). Electron microscopy (x13,800) studies of skin injection sites revealed that RANTES was chemoattractant for mast cells. In a Northern blot analysis from homogeneous tissue biopsy from the intradermal injection sites, RANTES was more potent than MCP-1 in increasing histidine decarboxylase (HDC) mRNA, the sole enzyme responsible for the production of histamine from histidine. Since PGD2 is formed by mast cells on cell activation, we also studied the effect of RANTES and MCP-1 on PGD2 production in inflamed tissue in vivo. RANTES (20, 10, and 5 ng) and MCP-1 (20, 10, and 5 ng) strongly stimulated PGD2, in a dose-dependent manner, with a potency rank order of RANTES (10 ng/mL) approximately two times greater than MCP-1 (10 ng/mL).  相似文献   
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Dust generation in solids handling involving free fall of bulk materials and impacts on a stockpile can cause many problems in industry and be a great danger for operators health. This paper describes an experimental set up to characterize the dust plume formed in free fall of powders from a hopper and investigates the influence of various outlet geometries on the dust plume. For this purpose an image analysis technique was developed to quantify the characteristics of the dust plume.  相似文献   
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The mediators of favorable multisystemic therapy (MST) outcomes achieved at 12 months postrecruitment were examined within the context of a randomized effectiveness trial with 127 juvenile sexual offenders and their caregivers. Outcome measures assessed youth delinquency, substance use, externalizing symptoms, and deviant sexual interest/risk behaviors; hypothesized mediators included measures of parenting and peer relations. Data were collected at pretreatment, 6 months postrecruitment, and 12 months postrecruitment. Consistent with the MST theory of change and the small extant literature in this area of research, analyses showed that favorable MST effects on youth antisocial behavior and deviant sexual interest/risk behaviors were mediated by increased caregiver follow-through on discipline practices as well as decreased caregiver disapproval of and concern about the youth’s bad friends during the follow-up. These findings have important implications for the community-based treatment of juvenile sexual offenders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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High‐temperature in situ synchrotron X‐ray powder diffraction experiments were carried out to investigate the phase transition mechanism of Zr2P2O9 (2ZrO2·P2O5 or “Z2P”). Linear thermal expansion coefficients were calculated for the low‐temperature phase (α‐Z2P) and the high‐temperature phase (β‐Z2P) from temperature‐dependent changes in lattice parameters. The crystal structures of α‐ and β‐Z2P were determined as a function of temperature by performing Rietveld crystal structure refinements. The structural changes at the phase transition are accompanied by an increase in the average atomic distance between neighboring Zr atoms. The occurrence of shorter metal–metal distances in α‐Z2P is interpreted to result from stronger interactions between partly occupied valence orbitals of the d0 metal atoms. The bond valence method was used to calculate the valence sums of the atoms of α‐ and β‐Z2P, respectively, considering also contributions resulting from covalently bonded atoms. As the bond strength between the metal atoms in Z2P decreases with the transition into the high‐temperature phase, notably, the metal–metal interactions are regarded to constitute a prerequisite for the stabilization of the α‐phase over the energetically favored β‐phase.  相似文献   
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A study on the extrusion of Eudragit E100 was carried out using supercritical carbon dioxide (scCO2) as plasticizer and foaming agent. ScCO2 modifies the rheological properties of the material in the barrel of the extruder and acts as a blowing agent during the relaxation when flowing through the die. For experiments, a single‐screw extruder was modified to be able to inject scCO2 within the extruded material. The aim is to determine a correlation between operating conditions and foam structure. The effect of three parameters was studied: the temperature in the die and in the metering zone, the screw speed, and the volumetric flow rate of CO2. An increase in temperature enhances the expansion rate and the average pore diameter and appears to be the most significant parameter. The effect of CO2 concentration is significant at small concentrations only: the higher the CO2 concentration, the lower the pore density and the higher both the pore diameter and the expansion rate. The effect of the screw speed is tricky because a variation of this speed involves a decrease of CO2 weight ratio. This study shows that the structure of the extrudates does not evolve with a coupling of screw speed increase and a subsequent CO2 weight ratio decrease. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   
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Processes using crystallisation from a supercritical medium constitute a new route to obtain finely divided solids. By using the pressure as an operating parameter, these processes allow to obtain fine and monodisperse powders. There exist two types of processes, according to whether supercritical fluid — usually carbon dioxide — is used as a solvent or an anti‐solvent: RESS or SAS. In the first case it is the drop in density due to the brutal decompression of the fluid which is the driving force of nucleation, in the second it is the reciprocal dissolution of an organic solvent in the supercritical fluid. Industrial applications are expected in many sectors, even if it is the pharmaceutical industry which seems best armed to gather a majority of its developments.  相似文献   
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