oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 1 )

2018 ( 4 )

2017 ( 9 )

2016 ( 26 )

Custom range...

Search Results: 1 - 10 of 4449 matches for " Denise Zampieri "
All listed articles are free for downloading (OA Articles)
Page 1 /4449
Display every page Item
Cellulase and Xylanase Production by Penicillium echinulatum in Submerged Media Containing Cellulose Amended with Sorbitol
Carla Eliana Todero Ritter,Marli Camassola,Denise Zampieri,Mauricio Moura Silveira,Aldo José Pinheiro Dillon
Enzyme Research , 2013, DOI: 10.1155/2013/240219
Abstract: The present work investigated the use of sorbitol as a soluble carbon source, in association with cellulose, to produce cellulases and xylanases in submerged cultures of Penicillium echinulatum 9A02S1. Because cellulose is an insoluble carbon source, in cellulase production, there are some problems with rheology and oxygen transfer. The submerged fermentations containing media composed of 0, 0.25, 0.5, 0.75, and 1% (w/v) sorbitol and cellulose that were added at different times during the cultivation; 0.2% (w/v) soy bran; 0.1% (w/v) wheat bran; and a solution of salts. The highest filter paper activity (FPA) ( ?IU·mL?1) was obtained on the seventh day in the medium containing 0.5% (w/v) sorbitol and 0.5% (w/v) cellulose added 24 h after the start of cultivation. However, the CMCases showed an activity peak on the sixth day ( ?IU·mL?1) in the medium containing 0.75% (w/v) sorbitol and 0.75% (w/v) cellulose added after 12 h of cultivation. The xylanases showed the highest activity in the medium with 0.75% (w/v) sorbitol and 0.25% (w/v) cellulose added 36 h after the start of cultivation. This strategy enables the reduction of the cellulose concentration, which in high concentrations can cause rheological and oxygen transfer problems. 1. Introduction Lignocellulosic biomass has been projected to be one of the main resources for economically attractive bioethanol production, and enzymatic hydrolysis is the most potent alternative process for the saccharification of its polymers. Cellulase is an enzyme complex capable of hydrolyzing cellulose into glucose molecules [1], and xylanases degrade xylan, the main carbohydrate present in some hemicelluloses, into xylose [2]. Although cellulases and xylanases have several industrial uses, the greatest potential use of these enzymes is in the enzymatic hydrolysis of lignocellulosic materials to produce second-generation ethanol [3]. The cellulase complex has three major hydrolases: the endo- -1,4-glucanases (EG I, EG II, EG III, EG IV, and EG V; EC 3.2.1.4), which hydrolyze the glucosidic bonds randomly in cellulose fiber; the exo- -1,4-glucanases or cellobiohydrolases (CBH I and CBH II; EC 3.2.1.91), which act on the reducing and nonreducing ends of polymers, releasing cellobiose; and the -1,4-glucosidases (BG I and BG II; EC 3.2.1.21), which hydrolyze oligosaccharides and cellobiose into glucose [4]. The xylanolytic complex capable of hydrolyzing xylan is usually composed of several enzymes, such as -1,4-endoxylanase, -xylosidase, -L-arabinofuranosidase, -glucuronidase, acetyl xylan esterase, and the phenolic,
Power-injectable peripherally inserted central catheters: a step-down access or a real alternative to standard central venous lines?
Fernando Zampieri
Critical Care , 2012, DOI: 10.1186/cc11294
Abstract: The authors argue that an advantage of P-PICCs is the possibility to deliver a faster infusion of fluids and/or drugs to critically ill patients. Since P-PICCs were not inserted during emergencies and in severe sepsis, however, the benefit of allowing high flow rates is limited to patients that develop haemodynamic distress after catheter placement. The advantage of allowing infusion of contrast media, although important, is no different from other peripheral noncentral venous devices.To help understand the role of P-PICCs and to compare complication rates with standard central lines (central venous catheters), it would therefore be interesting to know the severity of illness of patients that eventually received P-PICCs and the percentage of patients that had P-PICCs as their solo central line during their ICU stay. The time interval between admission to the ICU and P-PICC placement would also be interesting data, since the high dwell time reported by the authors suggests that P-PICCs were probably preferentially inserted in patients with prolonged critical illness. If most P-PICCs were inserted in stable chronic patients, the advantage of P-PICCs over conventional peripherally inserted central catheters (PICCs) would be limited in real-life clinical practice.In addition to comparing P-PICCs with central venous catheters, as suggested by the authors, perhaps further research should also focus on evaluating the role of the P-PICC as a step-down vascular access for stable critically ill patients.Mauro Pittiruti and Giancarlo ScoppettuoloAs our study was not a comparative study of the PICC versus the central venous catheter but a pilot retrospective study about the clinical performance of P-PICCs in the ICU, we do not have data comparing the severity of illness between the PICC group and the rest of the patients [1].Reviewing our population data, however, we found that in most cases - both in adults and in children - PICCs were inserted in the first 48 hours after admi
La causalité des maladies dans la Médecine Darwinienne
Fabio Zampieri
E? : Revista de Humanidades Médicas & Estudios Sociales de la Ciencia y la Tecnología , 2009,
Abstract: La Médecine Darwinienne est une nouvelle approche que a comme but l’application de la biologie évolutionniste à la médecine, en particulier la théorie de la sélection naturelle pour répondre à la question pourquoi on tombe malade . Cette nouvelle perspective se propose comme une pathologie générale avec des implications en clinique et en santé publique. Historiquement, il y a eu un précédent bien délimité dans les années entre 1880 et 1940, période dans laquelle beaucoup des médecins en Amérique et Europe ont essayés de utiliser la théorie Darwinienne pour justifier leur typologies raciales de la maladie. Il est clair que ces deux tentatives, nommées Darwinisme Médicale (1880-1940) et Médecine Darwinienne (1990 jusqu’au présent) sont profondément diverses. Un analyse de respectifs concepts de causalité des maladies peut donner certains éléments sur ces différences et sur la spécificité et fécondité de l’approche contemporaine.
Time-dependent Hypercritical Accretion onto Black Holes
Luca Zampieri
Physics , 1996,
Abstract: Results are presented from a time-dependent, numerical investigation of super-Eddington spherical accretion onto black holes with different initial conditions. We have studied the stability of stationary solutions, the non-linear evolution of shocked models and the time-dependent accretion from an expanding medium.
Completely integrable Hamiltonian systems with weak Lyapunov instability or isochrony
Gaetano Zampieri
Mathematics , 2010, DOI: 10.1007/s00220-011-1198-9
Abstract: The aim of this paper is to introduce a class of Hamiltonian autonomous systems in dimension 4 which are completely integrable and their dynamics is described in all details. They have an equilibrium point which is stable for some rare elements of the class, and unstable in most cases. Anyhow, it is linearly stable (all orbits of the linearized system are bounded) and no motion is asymptotic in the past, namely no non-constant solution has the equilibrium as limit point as time goes to minus infinity. In the unstable cases, there is a sequence of initial data which converges to the equilibrium point whose corresponding solutions are unbounded and the motion is slow. So instability is quite weak and perhaps no such explicit examples of instability are known in the literature. The stable cases are also interesting since the level sets of the 2 first integrals independent and in involution keep being non-compact and stability is related to the isochronous periodicity of all orbits near the equilibrium point and the existence of a further first integral. Hopefully, these superintegrable Hamiltonian systems will deserve further research.
Weak instability of Hamiltonian equilibria
Gaetano Zampieri
Mathematics , 2012,
Abstract: This is an expository paper on Lyapunov stability of equilibria of autonomous Hamiltonian systems. Our aim is to clarify the concept of weak instability, namely instability without non-constant motions which have the equilibrium as limit point as time goes to minus infinity. This is done by means of some examples. In particular, we show that a weakly unstable equilibrium point can be stable for the linearized vector field.
Involutions of real intervals
Gaetano Zampieri
Mathematics , 2013,
Abstract: This paper shows a simple construction of the continuous involutions of real intervals in terms of the continuous even functions. We also study the smooth involutions defined by symmetric equations. Finally, we review some applications, in particular the characterization of the isochronous potentials by means of smooth involutions.
Diffeomorphisms with Banach space domains
Gaetano Zampieri
Mathematics , 2012,
Abstract: Our basic element is a $C^1$ mapping $f:X\to Y$, with $X,Y$ Banach spaces, and with derivative everywhere invertible. So $f$ is a local diffeomorphism at every point. The aim of this paper is to find a sufficient condition for $f$ to be injective, and so a global diffeomorphism $X\to f(X)$, and a sufficient condition for $f$ to be bijective and so a global diffeomorphism onto $Y$. This last condition is also necessary in the particular case $X=Y=\R^n$. In these theorems the key role is played by nonnegative auxiliary scalar coercive functions.
Nonholonomic versus vakonomic dynamics
Gaetano Zampieri
Mathematics , 2012,
Abstract: The main aim of the present paper is to raise the doubt that vakonomic dynamics may not be satisfactory as a model for velocity dependent constraints.
A comparative analysis of standard accretion disks spectra: an application to Ultraluminous X-ray Sources
A. Lorenzin,L. Zampieri
Physics , 2009, DOI: 10.1111/j.1365-2966.2009.14435.x
Abstract: We compare standard models of accretion disks around black holes that include the appropriate zero-torque inner boundary condition and relativistic effects on the emission and propagation of radiation. The comparison is performed adopting the multicolor disk blackbody model (MCD) as reference and looking for the parameter space in which it is in statistical agreement with "more physical" accretion disk models. We find simple 'recipes' that can be used for adjusting the estimates of the physical inner radius of the disk, the black hole mass and the accretion rate inferred using the parameters of the MCD fits. We applied these results to four ULXs for which MCD spectral fits of their X-ray soft spectral components have been published and find that, in three cases (NGC 1313 X-1, X-2 and M 81 X-9), the black hole masses inferred for a standard disk around a Schwarzschild black hole are in the interval ~100-200 solar masses. Only if the black hole is maximally rotating are the masses comparable to the much larger values previously derived in the literature.
Page 1 /4449
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.