Search results for "HYDROLYSIS"
showing 10 items of 632 documents
Enhanced surface area in thermally stable pure mesoporous TiO2
2000
Abstract We describe here for the first time the surfactant-assisted synthesis of thermally stable mesoporous pure TiO 2 having a high surface area. Our synthetic approach to the chemistry of this system is based on the equilibrium between the hydrolysis and condensation reactions of the inorganic species and the organic–inorganic self-assembling processes. The use of titanatrane complexes helps to retard the hydrolysis and condensation reactions, thus allowing us to overcome the difficulties in preparing titanium dioxide mesoporous materials starting from highly reactive Ti-alkoxides. The mesoporous material has been characterized by TEM, XRD and N 2 adsorption–desorption isotherms and dis…
Autohydrolysis pretreatment of Arundo donax: a comparison between microwave-assisted batch and fast heating rate flow-through reaction systems
2015
Background: Autohydrolysis of lignocellulosic biomass in liquid hot water has been widely studied owing to its high efficiency and relatively low cost. In the perspective of industrial applications, continuous or semi-continuous processes are more interesting than batch systems. Moreover, microwave heating of pretreatment systems has been proposed to intensify the kinetics of the process. In this study, the autohydrolysis of Arundo donax was performed in pure liquid hot water using a microwave-heated batch reactor and a semi-continuous flow-through reaction system with fast heating rate at the same operating conditions with the aim of performing a systematic comparison between the two diffe…
Blend scaffolds with polyaspartamide/polyester structure fabricated via TIPS and their RGDC functionalization to promote osteoblast adhesion and prol…
2019
Target of this work was to prepare a RGDC functionalized hybrid biomaterial via TIPS technique to achieve a more efficient control of osteoblast adhesion and diffusion on the three-dimensional (3D) scaffolds. Starting from a crystalline poly(l-lactic acid) (PLLA) and an amorphous alpha,beta-poly(N-2-hydroxyethyl) (2-aminoethylcarbamate)-d,l-aspartamide-graft-polylactic acid (PHEA-EDA-g-PLA) copolymer, blend scaffolds were characterized by an appropriate porosity and pore interconnection. The PHEA-EDA-PLA interpenetration with PLLA improved hydrolytic susceptibility of hybrid scaffolds. The presence of free amino groups on scaffolds allowed to tether the cyclic RGD peptide (RGDC) via Michael…
Evaluation of biodegradability on polyaspartamide-polylactic acid based nanoparticles by chemical hydrolysis studies
2015
Here, the synthesis of two graft copolymers based on ?,?-poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) and poly(lactic acid) (PLA), the O-(2-aminoethyl)-O'-galactosyl polyethylene glycol (GAL-PEG-NH2) or the methoxypolyethylene glycol amine (H2N-PEG-OCH3) is described. Starting from the obtained PHEA-PLA-PEG-GAL and PHEA-PLA-PEG copolymers, polymeric nanoparticles were prepared by high pressure homogenization-solvent evaporation method. To demonstrate their biodegradability as a function of the matrix composition, a chemical stability study was carried out until 21 days by incubating systems in two media mimicking physiological compartments (pH 7.4 and pH 5.5). The degradability of both nan…
Petri Net Modelling of the Starch Enzymatic Liquefaction
2012
This paper investigates the use of the Petri Net modelling language for the description and analysis of the enzymatic reactions that are used for the starch liquefaction. The Coloured Petri Net formalism supported by the CPN Tools modelling and simulation environment is used. The pools of substrates and products are represented as the places and the possible reactions as the transition of the net. The concurrent reactions are modelled trough transitions that are enabled at the same time. The occurrence probabilities associated with each of these concurrent transitions are chosen as the model parameters. The analysis of the specific properties of the model is used to fit the model to data fr…
Über synthetische Matrizenreaktionen
2007
Molecularly homogeneous, polynuclear phenolic compounds were esterified with acrylic acid and methacrylic acid chlorides. The pcresyl esters of acrylic and methacrylic acid react in high dilution in boiling benzene with a large excess of radicals derived from AIBN in such manner that the growth step of the free-radical polymerization is prevented; this may be denoted a “suppressed” polymerization. The application of these conditions to the previously mentioned poly-nuclear esters results in the formation of molecularly homogeneous cyclooligomers (ladder oligomers). Alkaline hydrolysis of these oligomers permits recovery of the polynuclear phenols and yields molecularly homogeneous oligoacry…
Microbiological Profile and Bioactive Properties of Insect Powders Used in Food and Feed Formulations
2019
Microbiological, nutritional and bioactive properties of edible powders obtained from Acheta domesticus (house cricket) and Tenebrio molitor (mealworm) were investigated. Except for the enterobacteria, viable bacteria were at a higher concentration in mealworm flour. The diversity evaluation carried out using MiSeq Illumina that mainly identified Citrobacter and Enterobacteriaceae in mealworm powder and members of the Porphyromonadaceae family in house cricket powder. Enterococci were identified and characterized for their safety characteristics in terms of the absence of antibiotic resistance and virulence. Both powders represent a good source of proteins and lipids. The fatty acid profile…
Use of Silica Based Materials as Modulators of the Lipase Catalyzed Hydrolysis of Fats under Simulated Duodenal Conditions
2020
[EN] The effect of silica materials and their functionalization in the lipase catalyzed fat hydrolysis has been scarcely studied. Fifteen silica materials were prepared and their effect on the fat hydrolysis was measured, under simulated duodenal conditions, using the pH-stat method. The materials are composed of the combination of three supports (Stober massive silica nanoparticles, Stober mesoporous nanoparticles and UVM-7) and four surface functionalizations (methyl, trimethyl, propyl and octyl). In addition, the non-functionalized materials were tested. The functional groups were selected to offer a hydrophobic character to the material improving the interaction with the fat globules an…
Shedding of interleukin-6 receptor and tumor necrosis factor alpha. Contribution of the stalk sequence to the cleavage pattern of transmembrane prote…
2000
A functionally and structurally diverse group of transmembrane proteins including transmembrane forms of mediators or receptors can be proteolytically cleaved to form soluble growth factors or receptors. Recently, the proteolytic activity responsible for pro-tumor necrosis factor alpha (proTNFalpha) processing has been identified and named TACE (TNFalpha converting enzyme). In experiments with TACE deficient (TACE-/-) fibroblasts we found that 4beta-phorbol 12-myristate 13-acetate (PMA)-induced shedding of the interleukin-6 receptor (IL-6R) is strongly reduced. A basal hydroxamate sensitive release of IL-6R, however, could still be detected. This result demonstrates that TACE plays a role i…
A comparison of HONO budgets for two measurement heights at a field station within the boreal forest in Finland
2015
Atmospheric concentrations of nitrous acid (HONO), one of the major precursors of the hydroxyl radical (OH) in the troposphere, significantly exceed the values predicted by the assumption of a photostationary state (PSS) during daytime. Therefore, additional sources of HONO were intensively investigated in the last decades. This study presents budget calculations of HONO based on simultaneous measurements of all relevant species, including HONO and OH at two different measurement heights, i.e. 1 m above the ground and about 2 to 3 m above the canopy (24 m above the ground), conducted in a boreal forest environment. We observed mean HONO concentrations of about 6.5 × 108 molecules cm−3 (26 p…