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831.
Patrizia Lamanna H. Nilsson P. Reuse 《Journal of Thermal Analysis and Calorimetry》2008,93(1):329-333
When chemical reactions are performed in semi-batch mode and the reaction rate is relatively low, the reactant added may be
accumulated. The resulting thermal accumulation is of major concern regarding process safety, as a fault in the cooling system
may lead to a run-away reaction. The feed rate in semi-batch processes is usually constant, but this paper discusses methods
of optimizing the feed rate interactively, based on the measured heat flow and the calculated amount of compound that has
actually reacted. The prerequisite of such procedures is to run the experiments in a reaction calorimeter in which the heat
flows can be measured accurately and continuously. For this purpose a ChemiSens reaction calorimeter CPA202, which is calibration
free and gives stable, flat ‘zero-line-type’ baselines, was employed. 相似文献
832.
833.
Donati F Pucci A Cappelli C Mennucci B Ruggeri G 《The journal of physical chemistry. B》2008,112(12):3668-3679
In this work, two perylene derivatives containing different peripheral alkyl chains (i.e., N,N'-bis-(hexyl)perylene-3,4,9,10-tetracarboxyldiimide (ES-PTCDI) and N,N'-bis-(2'-ethylhexyl)perylene-3,4,9,10-tetracarboxyldiimide (EE-PTCDI)) were synthesized and efficiently dispersed at low loadings (from 0.01 to 0.1 wt %) into linear low-density polyethylene (LLDPE) by processing in the melt. Spectroscopic investigations (UV-vis and fluorescence) combined with quantum-mechanical studies demonstrated the ability of both chromophores to generate aggregates among the planar structure of dyes when dissolved in solution or dispersed into LLDPE above a certain concentration. The data acquired for dyes' dispersions into the polymer matrix reveal that the optical properties and responsiveness to mechanical stimuli are strongly dependent on the compactness of perylene aggregates provided by the different molecular structure of dyes. In particular, the strong intermolecular aggregates of ES-PTCDI resulted in being more resistant toward mechanical stress and less orientable by uniaxial drawing along the drawing direction of the film, whereas the less compact and distorted supramolecular architecture of EE-PTCDI chromophores provided composite films with a remarkable optical response to mechanical solicitations. 相似文献
834.
Unique intermolecular reaction of simple porphyrins at a metal surface gives covalent nanostructures
In't Veld M Iavicoli P Haq S Amabilino DB Raval R 《Chemical communications (Cambridge, England)》2008,(13):1536-1538
Deposition of a porphyrin onto metallic copper followed by heating leads to an unprecedented type of linking of the molecules giving a mixture of covalent multiporphyrin nanostructures at the surface. 相似文献
835.
Scarpino Schietroma DM Monaco MR Bucalossi V Walter PE Gentili P Bella M 《Organic & biomolecular chemistry》2012,10(24):4692-4695
A catalytic version of the Rabe electrophilic amination is presented. This kind of reaction was originally employed in 1918 in a key step for the conversion of quinotoxine to quinine. Ketones and α-substituted aldehydes give the corresponding α-aminated carbonyl compounds in moderate yield. α,α-Unsubstituted aldehydes give rise to amino ketones via a novel rearrangement. 相似文献
836.
Amatori S Ambrosi G Fanelli M Formica M Fusi V Giorgi L Macedi E Micheloni M Paoli P Pontellini R Rossi P Varrese MA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4274-4284
Ligand L (4-(7-nitrobenzo[1,2,5]oxadiazole-4-yl)-1,7-dimethyl-1,4,7,10-tetra-azacyclododecane) is a versatile fluorescent sensor useful for Cu(II), Zn(II) and Cd(II) metal detection, as a building block of fluorescent metallo-receptor for halide detection, and as an organelle marker inside live cells. Ligand L undergoes a chelation-enhanced fluorescence (CHEF) effect upon metal coordination in acetonitrile solution. In all three complexes investigated the metal cation is coordinatively unsaturated; thus, it can bind secondary ligands as anionic species. The crystal structure of [ZnLCl](ClO(4)) is discussed. Cu(II) and Zn(II) complexes are quenched upon halide interaction, whereas the [CdL](2+) species behaves as an OFF-ON sensor for halide anions in acetonitrile solution. The mechanism of the fluorescence response in the presence of the anion depends on the nature of the metal ion employed and has been studied by spectroscopic methods, such as NMR spectroscopy, UV/Vis and fluorescence techniques and by computational methods. Subcellular localization experiments performed on HeLa cells show that L mainly localizes in spot-like structures in a polarized portion of the cytosol that is occupied by the Golgi apparatus to give a green fluorescence signal. 相似文献
837.
Capriotti AL Caruso G Cavaliere C Foglia P Laganà A Samperi R 《Natural product research》2012,26(19):1787-1795
Polyphenol concentrations were quantified by rapid resolution liquid chromatography/mass spectrometry in white table grape. The experimental vineyard was subjected to different kinds of water supply and supply rates. Samples from the same vineyards were also analysed after 6 weeks of storage in a refrigerator and after 6 weeks of delayed harvesting. Berry skins and seeds were analysed separately. A statistical treatment of the screening kind, namely the 2(k) full factorial design, was used for the interpretation of results. Storage, delayed harvesting and the different kinds of water supply appeared to be the variables most affecting grape polyphenol content. In some cases, results showed that polyphenol content diminished by more than 50% after 6 weeks if the grapes were stored in a refrigerator, or if a sprinkler was used for irrigation. 相似文献
838.
Electrostatic assembly of Ag nanoparticles onto nanofibrillated cellulose for antibacterial paper products 总被引:1,自引:0,他引:1
Natércia C. T. Martins Carmen S. R. Freire Ricardo J. B. Pinto Susana C. M. Fernandes Carlos Pascoal Neto Armando J. D. Silvestre Jessica Causio Giovanni Baldi Patrizia Sadocco Tito Trindade 《Cellulose (London, England)》2012,19(4):1425-1436
Nanofibrillated cellulose offers new technological solutions for the development of paper products. Here, composites of nanofibrillated cellulose (NFC) and Ag nanoparticles (NP) were prepared for the first time via the electrostatic assembly of Ag NP (aqueous colloids) onto NFC. Distinct polyelectrolytes have been investigated as macromolecular linkers in order to evaluate their effects on the building-up of Ag modified NFC and also on the final properties of the NFC/Ag composite materials. The NFC/Ag nanocomposites were first investigated for their antibacterial properties towards S. aureus and K. pneumoniae microorganisms as compared to NFC modified by polyelectrolytes linkers without Ag. Subsequently, the antibacterial NFC/Ag nanocomposites were used as fillers in starch based coating formulations for Eucalyptus globulus-based paper sheets. The potential of this approach to produce antimicrobial paper products will be discussed on the basis of complementary optical, air barrier and mechanical data. 相似文献
839.
Giovanni Visco Susanne Heidi Plattner Patrizia Fortini Maria Pia Sammartino 《Chemistry Central journal》2012,6(1):1-17
Background
This paper discusses results obtained in the second monitoring campaign of the Carcer Tullianum, a particular hypogeum environment located in the historical centre of Rome (Italy). In the first paper we stressed the need to apply chemometric tools to this kind of studies in order to obtain full and significant information; really information on sampling design, sensors (type, number, position) and instrument validation seems to be not easy to find in literature for researches dealing with monitoring of indoor environments. Also in this case three main parameters (temperature, humidity, illuminance) were monitored in the complex construction by an inexpensive self-assembled system along some horizontal and vertical vectors together with some measurements of oxygen, carbon dioxide and barometric pressure. With respect to the first campaign, we used a higher number of sensors to cover a new excavated zone; for the same reason, as well as to take into account the presence of visitors, a different experimental design was adopted.Results
Different data treatments were applied to data coming from all the used sensors. A good view of the microclimate was obtained that also resulted coherent with the different position of the three rooms constituting the monitored site (Carcer, Tullianum, Convent). Classical time plots resulted useful to evidence the correlation of the main monitored parameters (T, RH% and illuminance) with macroclimate, as well as their delay in following macroclimate. Box-Whisker and Gain-Loss graphs evidenced at the best the microclimate differences between the three rooms; an almost hypogean microclimate was evidenced for the lower room (Tullianum) where humidity values range between 90 and 100% while lower values, but anyway higher than the external, and spread more widely were measured passing to Convent and Carcer with minimum values around 50% for the last. A scarce or very scarce correlation with macroclimate was evidenced for all the three main measured parameters. Lighting results mainly dependent on artificial light and only in few cases, but unfortunately in the most precious zone, illuminance exceeds values suggested by Normative.Conclusions
Box-Whisker and Gain-Loss graphs allowed us to have the best view of the microclimate for all the monitored rooms. The influence of lighting by lamps on the other monitored parameters resulted overlapped and clearly topped the solar one. The worst situation was found in the Carcer, where the presence of the main chandelier worsens the state of the frescoed walls, already subjected to wide changes in temperature and humidity. Also the lighthouse located above the Convent provokes lighting exceeding values suggested by Normative while, as expected, LEDs resulted as suitable source of light from a conservation point of view. Susanne Heidi Plattner, Patrizia Fortini and Maria Pia Sammartino contributed equally to this work 相似文献840.
David Cruz-Uribe Patrizia Di Gironimo Luigi D’Onofrio 《Czechoslovak Mathematical Journal》2012,62(1):111-116
In this paper we establish a continuity result for local minimizers of some quasilinear functionals that satisfy degenerate
elliptic bounds. The non-negative function which measures the degree of degeneracy is assumed to be exponentially integrable.
The minimizers are shown to have a modulus of continuity controlled by log log(1/|x|)−1. Our proof adapts ideas developed for solutions of degenerate elliptic equations by J. Onninen, X. Zhong: Continuity of solutions of linear, degenerate elliptic equations, Ann. Sc. Norm. Super. Pisa Cl. Sci. (5) 6 (2007), 103–116. 相似文献