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51.
52.
Franco David Troncoso Ignacio Oscar Costilla Gabriela Marta Tonetto 《Journal of the American Oil Chemists' Society》2022,99(8):697-710
In the present work, Pt/γ-Al2O3 catalysts with high metal dispersion were prepared and characterized using chloroplatinic acid and platinum acetylacetonate as metal precursors. The activity and selectivity of the catalysts were evaluated in the hydrogenation of sunflower oil. A comprehensive analysis of the effects of key operational parameters on catalytic performance was carried out. The experimental variables were hydrogen pressure (275.8–551.6 kPa), temperature (160–200°C), and catalyst loading (0.005–0.015 kg Ptexp/m3oil). Platinum catalysts were active, with a double bond conversion of 28% at 2 h. The metal precursor affected catalyst selectivity. The catalyst prepared with chloroplatinic acid exhibited a lower formation of trans-isomers compared with Pt acetylacetonate. The γ-Al2O3 supported platinum catalyst with a metal loading of 0.51 wt.% and a metal dispersion of 98% maintained its initial catalyst activity and selectivity after 10 consecutive uses (1200 min accumulate operation time), without changes in its catalytic properties. The obtained results suggested that Pt catalysts are an attractive alternative to conventional nickel catalysts for the hydrogenation of vegetable oil. 相似文献
53.
Ane H. Medeiros Fabiana B. Mingossi Renata O. Dias Flávia P. Franco Renato Vicentini Marcia O. Mello Daniel S. Moura Marcio C. Silva-Filho 《International journal of molecular sciences》2016,17(9)
Sugarcane’s (Saccharum spp.) response to Diatraea saccharalis (F.) (Lepidoptera: (Crambidae) herbivory was investigated using a macroarray spotted with 248 sugarcane Expressed Sequence Tags (ESTs) encoding serine peptidase inhibitors, serine peptidases. and Clp protease system subunits. Our results showed that after nine hours of herbivory, 13 sugarcane genes were upregulated and nine were downregulated. Among the upregulated genes, nine were similar to serine peptidase inhibitors and four were similar to Bowman-Birk Inhibitors (BBIs). Phylogenetic analysis revealed that these sequences belong to a phylogenetic group of sugarcane BBIs that are potentially involved in plant defense against insect predation. The remaining four upregulated genes included serine peptidases and one homolog to the Arabidopsis AAA+ chaperone subunit ClpD, which is a member of the Clp protease system. Among the downregulated genes, five were homologous to serine peptidases and four were homologous to Arabidopsis Clp subunits (three homologous to Clp AAA+ chaperones and one to a ClpP-related ClpR subunit). Although the roles of serine peptidase inhibitors in plant defenses against herbivory have been extensively investigated, the roles of plant serine peptidases and the Clp protease system represent a new and underexplored field of study. The up- and downregulated D. saccharalis genes presented in this study may be candidate genes for the further investigation of the sugarcane response to herbivory. 相似文献
54.
Rana Sabouni Aidan Leach Cedric Briens Franco Berruti 《American Institute of Chemical Engineers》2011,57(12):3344-3350
In this work, it was found that spray nozzles pulsations greatly improved the liquid feed spray distribution on fluidized bed particles. Pulsating a spray nozzle doubled its nozzle performance index at various operating conditions. The objective of this study was to impose fluctuations of well‐defined frequency and amplitude on the liquid spray to investigate potentially beneficial effects of fluctuations on the liquid feed distribution on the particles in the fluidized bed. Three sets of experiments were conducted to study the quality of the spray jet‐bed interaction using a conductance probe method. The jet penetration for each experiment was calculated theoretically. © 2011 American Institute of Chemical Engineers AIChE J, 2011 相似文献
55.
Nonisothermal crystallization of a segmented copolymer constituted by glycolide and trimethylene carbonate units was studied from both the melt and the glass state by optical microscopy, differential scanning calorimetry and time‐resolved X‐ray diffraction techniques. Positive spherulites with a fibrilar appearance were always obtained and corresponded to the crystallization of the polyglycolide hard segments. A single crystallization regime and the kinetic parameters were inferred from optical microscopy data on crystallizations performed at different cooling/heating rates. The parameters were in good agreement with values previously deduced from isothermal experiments. Isoconversional data of melt and glass nonisothermal crystallizations were combined to obtain the Lauritzen and Hoffman parameters from calorimetric data. Results revealed again the existence of a single crystallization regime with a secondary nucleation constant close to that deduced from isothermal DSC experiments. Morphological changes occurring during the hot and cold crystallization were evaluated by time‐resolved SAXS/WAXD experiments employing synchrotron radiation. Measurements showed that significant differences on the lamellar thicknesses exist depending on the crystallization process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
56.
Siva Ariyapadi Franco Berruti Ram Balachandar 《Chemical Engineering Communications》2003,190(12):1681-1704
The spray characteristics of a scaled-down version of an industrial feed nozzle are studied in the presence of a cross flow. Aerated liquid nitrogen is injected through the nozzle to generate the spray. The aeration rate is low and held constant, while two different liquid flow rates are used to produce the spray. A nonuniform wind profile is chosen to represent the cross flow condition. The droplet diameter and velocity measurements are acquired using a phase-Doppler particle analyzer. The results of the present study indicate that the spray momentum flux determines the extent of the jet bending. The droplets are accelerated significantly in the initial jet region as a result of flashing. However, further downstream of the nozzle, the vaporization of the droplets is considered to be negligible. The size-velocity correlation changes significantly for the case where the spray is shifted due to the cross flow. 相似文献
57.
Franco CacialliW.James Feast Richard H FriendMichel de Jong P.Wilfried LövenichWilliam R Salaneck 《Polymer》2002,43(12):3555-3561
Two new soluble block copolymers are reported in which chromophores and hexa(ethylene oxide) units alternate along the polymer backbone. In polymer 1 the chromophore was the distyrylbenzene unit. The polymer was synthesised via the Wittig reaction and the ionisation potential of 5.4±0.2 eV was measured by cyclic voltammetry and photoelectron spectroscopy. Polymer 1 showed a high solid-state photoluminescence efficiency (34%) and was used to make efficient (0.5 cd/A) light emitting diodes (LEDs). Polymer 1 was also used in light emitting cells; these showed luminescence in reverse bias and a reduced turn-on voltage compared to the LEDs. Polymer 2, in which the chromophore was dodecafluoro-distryrylbenzene, was prepared via the Horner-Wittig reaction and showed an ionisation potential of 6.25±0.15 eV and a solid-state photoluminescence efficiency of 17%. It was used as electron-conducting layer in a LED but failed to give significant electroluminescence. The optical energy gap for both polymers was 3.0 eV. 相似文献
58.
Simonetta Tuti Franco Pepe Daniela Pietrogiacomi Valerio Indovina 《Catalysis Today》2002,75(1-4):373-378
FeOx/ZrO2 samples, prepared by impregnation with Fe(NO3)3, were characterised by means of DRS, XRD, FTIR, redox cycles and volumetric CO adsorption. Volumetric CO adsorption, combined with FTIR, showed that 45% of iron in the sample containing 2.8 Fe atoms nm−2 was capable of forming iron carbonyls. DRS evidenced Fe2O3 on samples with Fe-content≥2.8 atoms nm−2. The selective catalytic reduction of NO with C3H6 in the presence of O2 was studied with a reactant mixture containing NO=4000 ppm, C3H6=4000 ppm, O2=2%. The dependence on iron-content suggests that only isolated iron, prevailing in dilute FeOx/ZrO2, is active for NO reduction, whereas iron on the surface of small oxide particles, prevailing in concentrated FeOx/ZrO2, is active for C3H6 combustion. 相似文献
59.
Summary
The copolymerization of styrene with 1-alkene (1-hexene, 1-decene and 1-hexadecene) has been tested using combined diphenylzinc-additive
initiator systems, including diphenylzinc (Ph2Zn), a metallocene and methylaluminoxane (MAO). The metallocene were biscyclopentadienyltitanium dichloride, bis(n-butylcyclopentadienyl)titanium
dichloride, cyclopentadienyltitanium trichloride and bisindenylzirconium dichloride. For Ph2Zn-metallocene-MAO systems, titanocenes gave mainly syndiotactic homo polystyrene irrespective of the styrene/1-alkene proportion
in the initial feed. Systems including Ind2ZrCl2 were able to copolymerize styrene 1-alkene with the copolymers incorporating alkene in a lower proportion than the present
in the initial feed.
Keywords: Styrene copolymerization; diphenylzinc; metallocene catalysts; tacticity.
Received: 17 November 2000/Revised version: 9 May 2001/Accepted: 10 May 2001 相似文献
60.
Josefina Pérez-Arantegui Judit Molera Angel Larrea Trinitat Pradell Marius Vendrell-Saz Ilaria Borgia Brunetto G. Brunetti Franco Cariati Paola Fermo Marcello Mellini Antonio Sgamellotti Cecilia Viti 《Journal of the American Ceramic Society》2001,84(2):442-46
Luster is a decorative metallic film that was applied on the surface of medieval glazed pottery. It can be obtained via the low-temperature (∼650°C), controlled reduction of copper and silver compounds. In this paper, we show that luster is a thin layered film (200–500 nm thick) that contains metallic spherical nanocrystals dispersed in a silicon-rich matrix and has a metal-free outermost glassy layer that is 10–20 nm thick. Silver nanocrystals seem to be separated from those of copper, forming aggregates 5–100 μm in diameter. This composite structure exhibits optical properties that are dependent on both the particle size and the matrix. Luster is indeed the first reproducible nanostructured thin metallic film that was made by humans. 相似文献