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Solid Material (solid + material)
Selected AbstractsInvestigation of the Development of Conflagration of Solid Material via Analysis of Coupled Heat, Mass and Momentum TransportCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2009U. Krause Abstract A mathematical model is presented for the transport of heat, mass and momentum transfer through a porous medium to simulate the chain of events from self-heating, subsequent self-ignition to smouldering fire propagation and burn-out of combustible fractions. The model comprises both diffusive and convective transport. The chemical reaction sub-model includes solid fuel decomposition and the combustion of char, carbon monoxide and hydrogen. Furthermore, biological processes, which may be a precursor of self-heating and vaporization/condensation of moisture, are also included into the model. All input data necessary for implementing the model have been determined experimentally. The model has been validated against laboratory scale self-ignition and smouldering propagation experiments and then applied to predictions of different fire scenarios during storage of bulk materials. [source] Structure Elucidation and Phytotoxicity of Ecdysteroids from Chenopodium albumCHEMISTRY & BIODIVERSITY, Issue 4 2005Marina DellaGreca The leaves of Chenopodium album were infused in H2O/MeOH. The extract treated with cold acetone gave heavy precipitation, which was removed by centrifugation. Solid material was fractionated into acidic and neutral fractions. The acidic material was subjected to different silica-gel column chromatographies, and then it was purified by reversed-phase HPLC to afford four known ecdysteroids and the new 3,,14, -dihydroxy-5, -pregn-7-ene-2,6,20-trione that were characterized by extensive spectroscopic investigation, especially by 1D- and 2D-NMR. Their effects on germination and growth of Lactuca sativa L. have been studied. The results are reported as percentage differences of germination, root elongation and shoot elongation, from the control at concentrations ranging from 10,4 to 10,7,M. [source] Simulation of heat transfer in the cool storage unit of a liquid,air energy storage systemHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 4 2002Hidefumi Araki Abstract An energy storage system that stores energy in the form of liquid air was studied. In this system, the cool storage unit was the most important unit. From the viewpoint of safety and economy, it was most promising to store the cold energy as the sensitive heat of a solid such as pebbles or concrete. A simulator was developed to predict temperature variations of the solid cool storage unit. The simulator calculated unsteady heat transfer between a supercritical gas flow and the solid material. Comparison of calculated and experimental results showed that the temperature variation of the metal cool storage medium was accurate within 11%. The calculated results showed for the concrete cool storage unit that a smaller quantity of medium was required with a smaller pitch of the tube. The minimum quantity of concrete calculated at the smallest pitch was three times that of concrete, which was simply estimated from the heat capacity of concrete and air. The volume required for concrete cool storage was less than 1/100 that of reservoirs for a pumped-hydro power station having a vertical drop of 500 m. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(4): 284,296, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10035 [source] Formation of Highly Crystallized ,-PbO Thin Films by Cathodic Electrodeposition of Pb and Its Rapid Oxidation in Air,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2005S. Sawatani Abstract The process of electrodeposition of ,-PbO thin films from aqueous solutions of PbII salts has been studied in detail. Contrary to the mechanism assumed in previous studies, thin films of crystalline ,-PbO are obtained after cathodic electrolysis in aqueous solutions of various soluble salts of PbII (Pb(NO3)2, Pb(ClO4)2, and Pb(CH3COO)2), and in both the presence and the absence of O2, thus indicating no contribution of OH, generation by electroreduction of NO3, and/or O2 to the formation of ,-PbO. A gradual color change is noted: a freshly electrodeposited gray film turns yellow as it dries in air. Drying of the films under controlled atmosphere (Ar or O2), combined with scanning electron microscopy (SEM) observation and X-ray diffraction (XRD) measurement, has revealed that freshly deposited films are of metallic Pb, which are oxidized and converted into ,-PbO. Such a reaction is operative only when a freshly electrodeposited activated wet Pb film is in contact with gaseous O2. Despite the rapid conversion of a solid material, the resultant ,-PbO thin films are highly crystallized and possess highly ordered internal nanostructure. Elongated nanoparticles (30,nm,×,100,nm) are assembled in a regular alignment to compose a large platelet (greater than 10,,m in size) with single-crystalline character, as revealed by transmission electron microscopy (TEM) observation and selected-area electron diffraction (SAED) measurement. [source] Uranium and thorium isotopes in the rivers of the Amazonian basin: hydrology and weathering processesHYDROLOGICAL PROCESSES, Issue 1 2003Aguinaldo N. Marques Jr. Abstract Two expeditions (October 1989 and May 1992) were carried out to two points of the main Amazon River channel and four tributaries. The Solimões and Madeira rivers, taking their origin in the Andes, are whitewater rivers. The Negro River is a typical acid, blackwater river. The Trombetas River flows through bauxite-rich areas, and is characterized by low concentrations of dissolved humic substances. The 238U, 234U, 232Th and 230Th activities were recorded from dissolved, suspended particulate phases and river bank sediments. The latter were analysed for their 226Ra, 228Ra and 210Pb contents, and also subjected to leaching with 0·2 M hydroxylamine,hydrochloride solution to determine the concentrations of radionuclides bound to amorphous Fe hydroxides and Mn oxides and hydroxides. The dissolved U average concentration in the Amazon system is ten times lower than the mean world river concentration. The uranium concentration observed at Óbidos in the lower Amazon (0·095 µg L,1), where the U content in the river bank sediments and suspended matter is lowest, suggests U release from the solid phase during river transport. About 485 t of U are transported annually to the Amazon delta area in dissolved form, and 1943 t bound to suspended particulate matter. Total U and Th concentrations in the river bank sediments ranged from 1·59 to 7·14 µg g,1 and from 6·74 to 32 µg g,1, respectively. The highest concentrations were observed in the Trombetas River. The proportion extracted by means of the hydroxylamine solution (HL) was relatively high for U in the Trombetas river bank sediment (31%) and for Th in the Solimões sediment (30%). According to the alpha recoil effects, the 234U/238U activity ratios of the Andean river waters and downstream Amazon water (Óbidos) were >1, but were <1 in the Negro River (at Manaus). The activity ratios of dissolved U correlate with pH and also with the U activity ratios in the river bank sediment hydroxylamine extracts. As expected, the 234U/238U activity ratios in river bank sediments were <1 in the Andean rivers and in the downstream Amazon, but they were >1 in the Trombetas and Negro rivers. Such ratios probably result from the binding of dissolved uranium to solid sediment. The 228Th/232Th ratios of river bank sediments were close to unity (except for the Negro River, where it is lower), suggesting no significant Th exchanges between the river water and the sediment. The 226Ra/232Th activity ratios were <1, and the 226Ra/228Ra activity ratios generally were significantly higher than the activity ratios of their respective parents. This perhaps is the result of easier leaching of the 226Ra parent, 230Th, from solid material (owing to the alpha recoil effect) than of the 228Ra parent. Uranium and thorium isotopes were used as tools to evaluate the chemical weathering rate of rocks in the Amazon system, which was estimated to be 2·7 cm 1000 year,1 s,1. Copyright © 2002 John Wiley & Sons, Ltd. [source] A numerical method for the evaluation of non-linear transient moisture flow in cellulosic materialsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2006U. Nyman Abstract A numerical method for the transient moisture flow in porous cellulosic materials like paper and wood is presented. The derivation of the model is based on mass conservation for a mixture containing a vapour phase and an adsorbed water phase embedded in a porous solid material. The principle of virtual moisture concentrations in conjunction with a consistent linearization procedure is used to produce the iterative finite element equations. A monolithic solution strategy is chosen in order to solve the coupled non-symmetric equation system. A model for the development of higher order sorption hysteresis is also developed. The model is capable of describing cyclic hardening as well as cyclic softening of the equilibrium water concentration. The model is verified by comparison with the measured response to natural variations in temperature and humidity. A close agreement of the simulated results to measured data is found. Copyright © 2005 John Wiley & Sons, Ltd. [source] FULLPAT: a full-pattern quantitative analysis program for X-ray powder diffraction using measured and calculated patternsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2002Steve J. Chipera FULLPAT is a quantitative X-ray diffraction methodology that merges the advantages of existing full-pattern fitting methods with the traditional reference intensity ratio (RIR) method. Like the Rietveld quantitative analysis method, it uses complete diffraction patterns, including the background. However, FULLPAT can explicitly analyze all phases in a sample, including partially ordered or amorphous phases such as glasses, clay minerals, or polymers. Addition of an internal standard to both library standards and unknown samples eliminates instrumental and matrix effects and allows unconstrained analyses to be conducted by direct fitting of library standard patterns to each phase in the sample. Standard patterns may include data for any solid material including glasses, and calculated patterns may also be used. A combination of standard patterns is fitted to observed patterns using least-squares minimization, thereby reducing user intervention and bias. FULLPAT has been coded into Microsoft EXCEL using standard spreadsheet functions. [source] Moxidectin and ivermectin metabolic stability in sheep ruminal and abomasal contentsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2005A. LIFSCHITZ The oral administration of macrocyclic lactones to sheep leads to poorer efficacy and shorter persistence of the antiparasitic activity compared to the subcutaneous treatment. Gastrointestinal biotransformation occurring after oral treatment to ruminant species has been considered as a possible cause of the differences observed between routes of administration. The current work was addressed to evaluate on a comparative basis the in vitro metabolism of moxidectin (MXD) and ivermectin (IVM) in sheep ruminal and abomasal contents. Both compounds were incubated under anaerobic conditions during 2, 6 and 24 h in ruminal and abomasal contents collected from untreated adult sheep. Drug concentrations were measured by high-performance liquid chromatography with fluorescence detection after sample clean up and solid phase extraction. Neither MXD nor IVM suffered metabolic conversion and/or chemical degradation after 24-h incubation in ruminal and abomasal contents collected from adult sheep. Unchanged MXD and IVM parent compounds represented between 95.5 and 100% of the total drug recovered in the ruminal and abomasal incubation mixtures compared with those measured in inactive control incubations. The partition of both molecules between the solid and fluid phases of both sheep digestive contents was assessed. MXD and IVM were extensively bound (>90%) to the solid material of both ruminal and abomasal contents collected from sheep fed on lucerne hay. The results reported here confirm the extensive degree of association to the solid digestive material and demonstrates a high chemical stability without evident metabolism and/or degradation for both MXD and IVM in ruminal and abomasal contents. [source] Treatment of mixed contamination in water using cyclodextrin-based materialsREMEDIATION, Issue 4 2006Shamil J. Cathum This study investigated the effectiveness of a cyclodextrin-based solid material for the removal of mixed dissolved contaminants. The solid material was prepared by condensation of ,-cyclodextrin. The removal efficiency was found to be 70 percent for total heavy metals (cadmium, lead, chromium, iron, nickel, cobalt, and mercury) to 98 percent for polychlorinated biphenyls (PCBs). The optimum pH for heavy metal removal was approximately 5 and for PCBs it was in the range of 5,7. All of these heavy metals were successfully recovered from the spent cyclodextrin-based material using nitric acid, allowing the material to be reused for further passes. The results also showed that the presence of alkaline and alkaline earth metals did not have a significant effect on the removal efficiency, indicating that the cyclodextrin-based material could selectively remove the heavy metals of concern without being consumed by alkaline and alkaline-earth metals. © 2006 Government of Canada. [source] Effect of solid material and surfactant presence on interactions of bubbles with horizontal solid surfaceTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010Mária Fujasová-Zedníková Abstract The interaction of a bubble with an immersed horizontal solid surface is studied experimentally. The effect of presence of a surfactant (limited to a specific nonionic surfactant, ,-terpineol, of various concentrations) and of surface material (cleaned glass, polypropylene, polyethylene, and Teflon) is investigated. The study focuses on two particular stages of the interaction, (i) the process of bubble bounce, which includes a collision and subsequent rebound from the solid surface, and (ii) the bubble attachment, which occurs after collision in time much longer than the duration of bounce and also after disappearance of all visible bubble movement. It is observed that the effect of the surface material on the bouncing is minor, possibly due to the liquid film separating the bubble and the solid surface. The presence of surfactant significantly affects the bouncing process. It not only decreases the initial bubble velocity, but also diminishes the bubble deformation after the collision and suppresses the bubble rebound from the surface. No rebound from the surface is observed in the most concentrated (1,×,10,3,mol/L) ,-terpineol solution. The adhesion time depends both on the solid material and ,-terpineol concentration. If the ,-terpineol concentration is increased, the adhesion time increases in the case of polypropylene surface, while it decreases in the case of polyethylene and Teflon surfaces. Results of this study are relevant for the description of attachment mechanism and to determine the proper conditions for selective flotation of plastics. L'interaction d'une bulle avec une surface pleine horizontale immergée est étudiée expérimentalement. L'effet de la présence d'un agent tensio-actif (limité à un agent tensio-actif nonionique spécifique, le ,-terpinéol, de diverses concentrations) et de matériau de surface (verre nettoyé, polypropylène, polyéthylène et Téflon) est étudié. L'étude se concentre sur deux étapes particulières de l'interaction, (i) le processus de rebondissement de la bulle, incluant une collision et un rebondissement subséquent de la surface pleine, et (ii) l'adhérence de la bulle, qui se produit après la collision, d'une durée plus longue que la durée du rebondissement, et également, après la disparition de tout mouvement visible de la bulle. Il est observé que l'effet du matériau de surface sur le rebondissement est mineur, probablement dû à la pellicule liquide séparant la bulle et la surface pleine. La présence de l'agent tensio-actif affecte de manière significative le processus de rebondissement. Elle diminue nonseulement la vitesse initiale de la bulle, mais diminue également la déformation de la bulle après la collision et supprime le rebondissement de la bulle de la surface. Aucun rebondissement de la surface n'est observé dans la solution la plus concentrée de ,-terpinéol (1,×,10,3,mol/L). La durée d'adhérence dépend aussi bien de la concentration du matériau solide que de la concentration en ,-terpinéol. Si la concentration en ,-terpinéol est augmentée, la durée d'adhérence augmente dans le cas de la surface en polypropylène, alors qu'elle diminue dans le cas des surfaces en polyéthylène et en Téflon. Les résultats de cette étude sont pertinents pour décrire le mécanisme d'adhérence et pour déterminer les conditions appropriées pour la flottaison sélective des plastiques. [source] Selective Binding of Imidazolium Cations in Building Multi-Component LayersCHEMISTRY - A EUROPEAN JOURNAL, Issue 23 2010Irene Ling Abstract Addition of 1-alkyl-3-methylimidazolium (Cn -mim) cations 3,5 to a mixture of bis-phosphonium cation 2 and sodium p -sulfonatocalix[4]arene (1) in the presence of lanthanide ions results in the selective binding of an imidazolium cation into the cavity of the calixarene. The result is a multi-layered solid material with an inherently flexible interplay of the components. Incorporating ethyl-, n -butyl- or n -hexyl-mim cations into the multi-layers results in significant perturbation of the structure, the most striking effect is the tilting of the plane of the bowl-shaped calixarene relative to the plane of the multi-layer, with tilt angles of 7.2, 28.9 and 65.5°, respectively. The lanthanide ions facilitate complexation, but are not incorporated into the structures and, in all cases, the calixarene takes on a 5, charge, with one of the lower-rim phenolic groups deprotonated. ROESY NMR experiments and other 1H,NMR spectroscopy studies establish the formation of 1:1 supermolecules of Cn -mim and calixarene, regardless of the ratio of the two components, and indicate that the supermolecules undergo rapid exchange on the NMR spectroscopy timescale. [source] INACTIVATION OF STAPHYLOCOCCUS AUREUS EXPOSED TO DENSE-PHASE CARBON DIOXIDE IN A BATCH SYSTEMJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2009HUACHUN HUANG ABSTRACT The inactivation of Staphylococcus aureus exposed to dense-phase carbon dioxide (DPCD) was investigated, and the kinetics of come-up time (CUT) in pressurization was monitored with come-down time (CDT) and temperature fluctuation in depressurization. CUT was about 2.5, 3.5, 4.0 and 4.0 min; CDT was 3.4, 3.7, 4.5 and 4.5 min; lowest temperature of samples in depressurization was 4, ,1, ,15 and ,22C, corresponding to 10, 20, 30 and 40 MPa at 37C. The inactivation behavior of S. aureus was closely related to the variables of process pressure, holding-pressure time (HPT), process temperature and process cycling. The log reduction of S. aureus at 40 MPa for 30-min HPT was significantly greater (P < 0.05), but the inactivation effect at 10, 20 and 30 MPa was similar. The log reduction of S. aureus at 30 and 40 MPa for 60-min HPT was similar and significantly greater (P < 0.05), while the inactivation effect at 10 and 20 MPa was similar. The inactivation of S. aureus against HPT conformed to a fast,slow biphase kinetics; the two stages were well fitted to a first-order model with higher regression coefficients R2 = 1.000 and 0.9238; their respective D values (decimal reduction time) were 16.52 and 70.42 min. As the process temperature increased, the log reduction of S. aureus increased significantly (P < 0.05); the inactivation kinetics of S. aureus versus process temperature was characterized with a fast inactivation rate from 32 to 45C and a slow inactivation rate from 45 to 55C. As compared to one-process cycling for a total of 60-min HPT, four-process cycling resulted in a significant reduction of S. aureus, and its maximal reduction was near to 5 log cycles, indicating that more process cycling caused more inactivation of S. aureus under identical pressure and temperature with equal HPT. However, the maximal reduction was 0.09 and 0.12 log cycles for two- and four-process cyclings with 0-min HPT, indicating that pressurization and depressurization had a lesser effect on the inactivation of S. aureus, while HPT was significant in DPCD to inactivate S. aureus. PRACTICAL APPLICATIONS Dense-phase carbon dioxide (DPCD) is a novel technology to achieve cold pasteurization and/or sterilization of liquid and solid materials, and is likely to replace or partially substitute currently and widely applied thermal processes. This study showed that DPCD effectively inactivated Staphylococcus aureus inoculated in 7.5% sodium chloride broth, and the inactivation behavior of S. aureus was closely related to the pressure, holding-pressure time, temperature and process cycling. Based on this observation, the technology of DPCD can be applied in the pasteurization of foods such as milk and various fruit juices, especially thermal-sensitive materials. [source] Cement Manufacture and the Environment: Part I: Chemistry and TechnologyJOURNAL OF INDUSTRIAL ECOLOGY, Issue 1 2002Hendrik G. van Oss Summary Hydraulic (chiefly portland) cement is the binding agent in concrete and mortar and thus a key component of a country's construction sector. Concrete is arguably the most abundant of all manufactured solid materials. Portland cement is made primarily from finely ground clinker, which itself is composed dominantly of hydraulically active calcium silicate minerals formed through high-temperature burning of limestone and other materials in a kiln. This process requires approximately 1.7 tons of raw materials per ton of clinker produced and yields about 1 ton of carbon dioxide (CO2) emissions, of which cal-cination of limestone and the combustion of fuels each con-tribute about half. The overall level of CO2 output makes the cement industry one of the top two manufacturing industry sources of greenhouse gases; however, in many countries, the cement industry's contribution is a small fraction of that from fossil fuel combustion by power plants and motor vehicles. The nature of clinker and the enormous heat requirements of its manufacture allow the cement industry to consume a wide variety of waste raw materials and fuels, thus providing the opportunity to apply key concepts of industrial ecology, most notably the closing of loops through the use of by-products of other industries (industrial symbiosis). In this article, the chemistry and technology of cement manufacture are summarized. In a forthcoming companion ar-ticle (part II), some of the environmental challenges and op-portunities facing the cement industry are described. Because of the size and scope of the U.S. cement industry, the analysis relies primarily on data and practices from the United States. [source] Dehydration studies using a novel multichamber microscale fluid bed dryer with in-line near-infrared measurementJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2003Eetu Räsänen Abstract The purpose of this research was to study the effect of two process parameters (temperature and moisture content) on dehydration behavior of different materials using a novel multichamber microscale fluid bed dryer with a process air control unit and in-line near-infrared (NIR) spectroscopy. The materials studied were disodium hydrogen phosphates with three different levels of hydrate water and wet theophylline granules. Measured process parameters of fluid bed drying were logged, including in-line NIR signals. Off-line analyses consisted of X-ray powder diffraction patterns, Fourier transform NIR spectra and moisture contents of studied materials. During fluid bed drying, the stepwise dehydration of materials was observed by the water content difference of inlet and outlet air, the pressure difference over the bed, and the in-line NIR spectroscopy. The off-line analysis confirmed the state of solid materials. The temperature and the moisture content of the process air were demonstrated to be significant factors for the solid-state stability of theophylline. The presented setup is a material and cost-saving approach for studying the influence of different process parameters on dehydration behavior during pharmaceutical processing. © 2003 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 92:2074,2081, 2003 [source] Studying porous materials with krypton-83 NMR spectroscopyMAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2007Zackary I. Cleveland Abstract This report is the first review of 83Kr nuclear magnetic resonance as a new and promising technique for exploring the surfaces of solid materials. In contrast to the spin I = 1/2 nucleus of 129Xe, 83Kr has a nuclear spin of I = 9/2 and therefore possesses a nuclear electric quadrupole moment. Interactions of the quadrupole moment with the electronic environment are modulated by surface adsorption processes and therefore affect the 83Kr relaxation rate and spectral lineshape. These effects are much more sensitive probes for surfaces than the 129Xe chemical shielding and provide unique insights into macroporous materials in which the 129Xe chemical shift is typically of little diagnostic value. The first part of this report reviews the effect of quadrupolar interactions on the 83Kr linewidth in zeolites and also the 83Kr chemical shift behavior that is distinct from that of its 129Xe cousin in some of these materials. The second part reviews hyperpolarized (hp) 83Kr NMR spectroscopy of macroporous materials in which the longitudinal relaxation is typically too slow to allow sufficient averaging of thermally polarized 83Kr NMR signals. The quadrupolar-driven T1 relaxation times of hp 83Kr in these materials are sensitive to surface chemistry, surface-to-volume ratios, coadsorption of other species on surfaces, and surface temperature. Thus, 83Kr T1 relaxation can provide information about surfaces and chemical processes in macroscopic pores and can generate surface-sensitive contrast in hp 83Kr MRI. Copyright © 2007 John Wiley & Sons, Ltd. [source] Investigation of norflurazon pesticide photodegradation using plasma desorption time-of-flight mass spectrometry analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2008J.-P. Thomas We have previously demonstrated that PD-TOFMS (plasma desorption time-of-flight mass spectrometry) analysis is a powerful technique for the in situ analysis of pesticides deposited or adsorbed on solid materials. With the aim of producing reproducible data on the modification of a pesticide under controlled photodegradation conditions, we have now undertaken a study where both the substrate and the pesticide are well characterized. This is the case for norflurazon deposited onto an aluminium substrate, in particular regarding the reproducibility of preparation of the samples and the change with time of their chemical composition. Degradation parameters have been derived from the variation in yield of ions representative of the molecule and of its breakdown products and, particularly, from the time required for 50% dissipation of their initial concentration (DT50). DT50 values ranging between 1 and 10,h have been found. An interpretation of the degradation process is proposed from the decay of other ions. As expected, the degradation is faster when the UV sunlight is unfiltered (a factor of 3.8 for the molecule, and around 5 for the breakdown products). Copyright © 2008 John Wiley & Sons, Ltd. [source] New route to synthesis of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross-coupling reactionsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 12 2009Feyyaz Durap Abstract Herein we report a new method for the synthesis and characterization of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP-stabilized palladium(0) nanoclusters with a particle size of 4.5 ± 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 °C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV,vis, and XRD techniques. The PVP-stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP-stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright © 2009 John Wiley & Sons, Ltd. [source] Non-thermal bacterial inactivation with dense CO2BIOTECHNOLOGY & BIOENGINEERING, Issue 6 2003S. Spilimbergo Abstract The use of CO2 under pressure (dense CO2) is one of the most promising techniques to achieve cold pasteurization and/or sterilization of liquid and solid materials, and is likely to replace or partially substitute currently and widely applied thermal processes. Although the ability of CO2 to inactivate microorganisms has been known since the 1950's, only within the last 15 years it has received special attention, and the scientific and economic interest towards practical applications is presently growing more and more. Here we collect and discuss the relevant current knowledge about the potentials of dense CO2 as a non-thermal technology in the field of microbial inactivation. We summarize the state of the art, including definitions, description of the equipment, relevant applications, in both simple suspensions and complex media, for the treatment of a wide range of microorganisms in both liquid and solid substrates. Finally, we also summarize and discuss the different hypotheses about the mechanisms of inactivation © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng84: 627,638, 2003. [source] Systematic Investigation of Molecular Arrangements and Solid-State Fluorescence Properties on Salts of Anthracene-2,6-disulfonic Acid with Aliphatic Primary AminesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Yuji Mizobe Dr. Abstract Organic salts of anthracene-2,6-disulfonic acid (ADS) with a wide variety of primary amines have been fabricated, and their arrangements of anthracene molecules and solid-state fluorescence properties investigated. Single-crystal X-ray studies reveal that the salts show seven types of crystal forms and corresponding molecular arrangements of anthracene moieties depending on the amine, while anthracene shows only one form and arrangement in the solid state. Depending on the molecular arrangements, the ADS salts exhibit various solid-state fluorescence properties: spectral shift (30,nm) and suppression and enhancement of the fluorescence intensity. Especially the ADS salt with n -heptylamine (nHepA), which shows discrete anthracene moieties in the crystal, exhibits the highest quantum yield (,F=46.1±0.2,%) in the series of ADS salts, which exceeds that of anthracene crystal (,F=42.9±0.2,%). From these systematic investigations on the arrangements and the solid-state properties, the following factors are essential for high fluorescence quantum yield in the solid state: prevention of contact between , planes of anthracene moieties and immobilization of anthracene rings. In addition, such organic salts have potential as a system for modulating the molecular arrangements of fluorophores and the concomitant solid-state properties. Thus, systematic investigation of this system constructs a library of arrangements and properties, and the library leads to remarkable strategies for the development of organic solid materials. [source] | |||||||||||||||||||