1,825 research outputs found
Masonry wall panels retrofitted with thermal-insulating GFRP-reinforced jacketing
No full textToday there is a need to provide thermally efficient walls, while at the same time to increase the mechanical properties of old unreinforced masonry walls that will not require large amounts of energy in the retrofitting or deconstruction processes. To address this problem, this paper gives the results of shear tests carried out on masonry panels made of solid bricks retrofitted with a new technique based on the use of glass fiber-reinforced polymers (GFRP) grids inserted into a thermal insulating jacketing. This was made of different low-strength lime-based mortars. Tests were carried out in laboratory and results were used for the determination of the shear modulus and strength of the wall panels before and after the application of the GFRP reinforcement. Retrofitted panels exhibited a significant enhancement in the lateral capacity when compared to the control panels. The thermal performance of the proposed mortars was also investigated both with and without GFRP. Low values of thermal conductivity were found, especially for the samples with GFRP; a reduction of the thermal transmittance value in the 34–45 % range was also obtained by applying 45 mm layer of coating in conventional masonry walls
Introduzione
No full textSi tratta dell'introduzione alla miscellanea in onore di G. Avarucci curata dallo stesso Borri e da R. M. Borraccini
The Binding of the Coenzyme Pyridoxal 5'-Phosphate and Analogues of the Substrate-Coenzyme Complex to Tyrosine Decarboxylase
No full textPhosphopyridoxyl derivatives, which are stable analogues of a substrate-coenzyme
complex, are bound at the active site with great affinity. From a comparison of the interaction
of a number of such compounds with the apoenzyme the AGO values for the binding
of the substrate carboxy and phenyl groups and of the coenzyme aldehydic group were
determined to be equal to (or more negative than) -3.8,-8.4 and -12.5 kJ/mol (-0.9,-1.9
and -3 kcal/mol) respectively; the AGO for the binding of the coenzyme phosphate group
was shown to be more negative than -20.5kJ/mol (-4.9 kcal/mol). Two features of the
binding process of the coenzyme-substrate analogues to tyrosine decarboxylase have
already been found in the case of tyrosine aminotransferase [Borri-Voltattorni, Orlacchio,
Giartosio, Conti & Turano (1975) Eur. J. Biochem. 53, 151-160]: (1) in the binding of the
substrate to the enzyme a significant fraction of the intrinsic AGO appears to be used for
some associated endoergonic process; (2) the AH0 and AS0 of binding appear to be very
sensitive indicators of the correct alignment of the substrate-coenzyme analogues at the
active site
Shear strengthening of wall panels through jacketing with cement mortar reinforced by GFRP grids
No full textThis paper gives the results of a series of shear tests carried out on historic wall panels reinforced with an innovative technique by means of jacketing with GFRP (Glass Fiber Reinforced Plastics) mesh inserted into an inorganic matrix. Tests were carried out in situ on panels cut from three different historic buildings in Italy: two in double-leaf rough hewn rubble stone masonry in Umbria and L'Aquila and another with solid brick masonry in Emilia. Two widely-known test methods: the diagonal compression test and the shear-compression test with existing confinement stress. The test results enabled the determination of the shear strength of the masonry before and after the application of the reinforcement. The panels strengthened with the GFRP exhibited a significant improvement in lateral load-carrying capacity of up to 1060% when compared to the control panels. A numerical study assessed the global behavior and the stress evolution in the unreinforced and strengthened panels using a finite element code
Ornithine and glutamate decarboxylases catalyse an oxidative deamination of their alpha-methyl substrates
No full textOrnithine decarboxylase (ODC) from Lactobacillus 30a catalyses the cleavage of α-methylornithine into ammonia and 2-methyl-1-pyrroline; glutamate decarboxylase (GAD) from Escherichia coli catalyses the cleavage of α-methylglutamate into ammonia and laevulinic acid. In our analyses, 2-methyl-1-pyrroline and laevulinic acid were identified by HPLC and mass spectroscopic analysis, and ammonia was identified by means of glutamate dehydrogenase. Molecular oxygen was consumed during these reactions in a 1:2 molar ratio with respect to the products. The catalytic efficiencies (kcat/Km) of the reactions catalysed by ODC and GAD were determined as 12500 and 9163 M-1 ̇min-1 respectively. When the reactions were performed under anaerobic conditions, no ammonia, 2-methyl-1-pyrroline or laevulinic acid was produced to a significant extent. The formation of ammonia and O2 consumption (in a 1:2 molar ratio with respect to ammonia) were also detected during the reaction of ODC and GAD with putrescine and γ-aminobutyrate respectively. Taken together, these findings clearly indicate that ODC and GAD catalyse an oxidative deamination of their decarboxylation products, a reaction similar to that catalysed by dopa decarboxylase (DDC) with α-methyldopa [Bertoldi, Dominici, Moore, Maras and Borri Voltattorni (1998) Biochemistry 37, 6552-6561]. Furthermore, this reaction was accompanied by a decarboxylation-dependent transamination occurring for GAD, DDC and ODC with a frequency of approx. 0.24%, 1% and 9% respectively compared with that of oxidative deamination.Ornithine decarboxylase (ODC) from Lactobacillus 30a catalyses the cleavage of alpha-methylornithine into ammonia and 2-methyl-1-pyrroline; glutamate decarboxylase (GAD) from Escherichia coli catalyses the cleavage of alpha-methylglutamate into ammonia and laevulinic acid. In our analyses, 2-methyl-1-pyrroline and laevulinic acid were identified by HPLC and mass spectroscopic analysis, and ammonia was identified by means of glutamate dehydrogenase. Molecular oxygen was consumed during these reactions in a 1.2 molar ratio with respect to the products. The catalytic efficiencies (k(cat)/K-m) of the reactions catalysed by ODC and GAD were determined as 12500 and 9163 M-1.min(-1) respectively. When the reactions were performed under anaerobic conditions, no ammonia, 2-methyl-1-pyrroline or laevulinic acid was produced to a significant extent. The formation of ammonia and O-2 consumption (in a 1:2 molar ratio with respect to ammonia) were also detected during the reaction of ODC and GAD with putrescine and gamma-aminobutyrate respectively. Taken together, these findings clearly indicate that ODC and GAD catalyse an oxidative deamination of their decarboxylation products. a reaction similar to that catalysed by dopa decarboxylase (DDC) with alpha-methyldopa [Bertoldi, Dominici, Moore, Maras and Borri Voltattorni (1998) Biochemistry 37, 6552-6561]. Furthermore, this reaction was accompanied by a decarboxylation-dependent transamination occurring for GAD, DDC and ODC with a frequency of approx. 0.24%, 1% and 9% respectively compared with that of oxidative deamination
Interaction of N-(DL-seryl)N'-(2,3,4-trihydroxybenzyl)-hydrazine with L-dopa decarboxylase from pig kidney.
No full textInteraction of L-alpha-methyl-alpha-hydrazino-3,4 dihydroxyphenylpropionic acid with dopa-decarboxylase from pig kidney.
No full textC to Work
No full textBorri S., C to Work, Video presentato in occasione del seminario "Spazi di apprendimento emergenti. Il divenire formativo nei contesti di coworking, FabLab e università", Roma, Auditorium Isfol, 27 maggio 2016. Isfol OA: Video. Illustra il percorso formativo “C to work” che lo spazio di coworking Piano C dedica alle donne che dopo la maternità vogliono rientrare nel mercato del lavoro. Per consultare il video, attivare il seguente link: 27/05/2016video. illustra il percorso formativo “c to work” che lo spazio di coworking piano c dedica alle donne che dopo la maternità vogliono rientrare nel mercato del lavoro. per consultare il video, attivare il seguente link: 27/05/2016 c to work sofia borr
Reinforcement of wood with natural fibers
No full textThis paper describes an experimental programme which examines the reinforcement in flexure of timber beams with composite materials based on natural fibers in the form of fabrics made from hemp, flax, basalt and bamboo fibers. The industrial use of natural fibers has been continuously increasing since 1990s due to their advantages in terms of production costs, pollution emissions and energy consumption for production and disposal. The technique allows the reinforcement of the intrados of beams, avoiding the dismantling of the overlying part of the structure with significant savings in terms of costs and work time. The test program consists of three phases incorporating 45 beams. The bending tests on the wooden elements made it possible to measure the increase in capacity and stiffness resulting from the composite reinforcement. This was applied to beams, creating different arrangements and using different quantities (number of layers). Despite the diversity of the various tests carried out, the results obtained in some cases showed significant increases in terms of load-carrying capacity and in deflection ductility
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