940 research outputs found
Experimental study on heat recovery using multi tube tank: effect of changing the head shape
This work presents a heat recovery system utilized to heat water from exhaust
gases of a chimney. A waste heat recovery system is suggested named as âmulti tube tankâ. The suggested design is illustrated and described. The system is constructed and tested. In order to enhance the system effect of changing the head shape is studied. Two head were constructed: cylindrical and conical. Results shows that conical head reflected better performance compared to cylindrical head. For a cylindrical head water temperature increase to maximum 60 °C in 275 min. while for conical 16 head water temperature increased to 70 °C in 275 min and the system was able to increase the water temperature more up to 80 °C in 400 min
Epidermolysis Bullosa in children: the central role of the pediatrician
Epidermolysis bullosa (EB) is a severe hereditary disease characterized by defective epithelial adhesion causing mucocutaneous fragility. The major types are EB simplex (EBS), junctional EB (JEB), dystrophic EB (DEB) and more than 35 EB subtypes. Another very rare type of EB is Kindler EB (KEB). Clinically, it is a very heterogeneous disease which ranges from localized to extensive skin lesions with frequent multisystem extra cutaneous involvement. The role of a pediatrician-dermatologist cooperation within a multidisciplinary team is fundamental for both the diagnosis and management contributing to these patients' better life expectancy. Aim of this study is to describe clinical and laboratory characteristics of the main EB subtypes focusing on nutritional and gastrointestinal aspects, providing information to aid the paediatric management of children with EB. This retrospective study reviewed the cases of 160 pediatric EB patients (76 male and 84 female): 31 patients affected by EBS (mean age +/- SD: 4.37 +/- 7.14), 21 patients affected by JEB (mean age +/- SD: 9.26 +/- 17.30) and 108 with DEB (mean age +/- SD: 11.61 +/- 13.48). All patients were admitted at the Bambino Gesu Children's Hospital in Rome, between June 2005 to June 2020. The reduced gastrointestinal absorption, chronic losses, esophageal stenosis and chronic inflammatory state, represent the basis of nutritional problems of EB patients. In particular, anemia represents one of the most important complications of DEB patients which could require transfusion-dependent patterns. Malnutrition, vitamin deficiencies and anemia have been related to growth delay in EB patients. A specific diet with a balance of all macronutrients is required and improving caloric intake with sugar limitations is fundamental to prevent dental caries and tooth decay typical of EB patients. While sepsis proved to be the major cause of morbidity and mortality in younger patients, squamous cell carcinoma was mostly observed in older patients, especially those affected by DEB. Patients with EB require regular monitoring for complications and sequelae with a frequency of evaluations which varies based on age and EB subtypes. Cooperation among medical teams involving paediatricians, dermatologists, specialist clinicians including nutritionists such as families and patient's association is fundamental to approach the disease and improve the quality of life of these patients
On perturbations of Dirac operators with variable magnetic field of constant direction
We carry out the spectral analysis of matrix valued perturbations of
3-dimensional Dirac operators with variable magnetic field of constant
direction. Under suitable assumptions on the magnetic field and on the
pertubations, we obtain a limiting absorption principle, we prove the absence
of singular continuous spectrum in certain intervals and state properties of
the point spectrum. Various situations, for example when the magnetic field is
constant, periodic or diverging at infinity, are covered. The importance of an
internal-type operator (a 2-dimensional Dirac operator) is also revealed in our
study. The proofs rely on commutator methods.Comment: 12 page
Investigation of Parietal Polysaccharides from Retama raetam Roots
This study characterizes the cell wall hemicellulose and pectins polymers of Retama raetam. This species develops a particularly important root system and is adapted to arid areas. The cellulose, hemicelluloses and pectins were extracted. The cellulose remains the major component of the wall (27% for young roots and 80% for adult roots), hemicelluloses (14.3% for young roots and 3.6% for adult roots) and pectins (17.3% for young roots and 4.1% for adult roots). The monosaccharidic composition of water soluble extracts determined by gas liquid chromatography (GLC) and completed by infrared (FTIR) spectroscopy of hemicellulosic shows the presence of xylose as a major monosaccharide in the non-cellulose polysaccharides (47.8% for young roots and 59.5% for adult roots). These results indicate the presence of the homogalacturonans and rhamnogalacturonans in pectin. This study constitutes the preliminary data obtained in the biochemical analysis of the parietal compounds of the roots of a species which grows in an arid area in comparison with those of its aerial parts.Keywords: Retama raetam, Roots, Cell Wall, Investigation, Polysaccharides, Monosaccharidi
Expression of enzymatically inactive wasp venom phospholipase A1 in Pichia pastoris
Wasp venom allergy is the most common insect venom allergy in Europe. It is manifested by large local reaction or anaphylactic shock occurring after a wasp sting. The allergy can be treated by specific immunotherapy with whole venom extracts. Wasp venom is difficult and costly to obtain and is a subject to composition variation, therefore it can be advantageous to substitute it with a cocktail of recombinant allergens. One of the major venom allergens is phospholipase A1, which so far has been expressed in Escherichia coli and in insect cells. Our aim was to produce the protein in secreted form in yeast Pichia pastoris, which can give high yields of correctly folded protein on defined minimal medium and secretes relatively few native proteins simplifying purification. Residual amounts of enzymatically active phospholipase A1 could be expressed, but the venom protein had a deleterious effect on growth of the yeast cells. To overcome the problem we introduced three different point mutations at the critical points of the active site, where serine137, aspartate165 or histidine229 were replaced by alanine (S137A, D165A and H229A). All the three mutated forms could be expressed in P. pastoris. The H229A mutant did not have any detectable phospholipase A1 activity and was secreted up to the level of 4 mg/L in shake flask culture. It was purified by nickelâaffinity chromatography and its identity was confirmed by MALDIâTOF mass spectrometry. The protein could bind IgE antibodies from wasp venom allergic patients and could inhibit the binding of wasp venom to IgE antibodies specific for phospholipase A1 as shown by Enzyme AllergoâSorbent Test (EAST). Moreover, the recombinant protein was allergenic in a biological assay as demonstrated by its capability to induce histamine release of wasp venomâsensitive basophils. The recombinant phospholipase A1 presents a good candidate for wasp venom immunotherapy
Experimental design of a diversion structure of granular debris flows
Many alpine torrents convey regularly debris flows of high destructive hazard. After several granular events observed in Bruchji?s torrent near the Blatten village in the Swiss Alps, it was decided to manage the risk of similar debris flows by designing and constructing a control structure inside the torrent bed. Associated with a breach in the right bank side of the torrent, this control structure should divert part of the moderate and high debris flow events toward the original alluvial cone. Two different configurations of the control structure were tested and optimized through a series of physical tests. The basic concept of this structure is to create a local lateral contraction of the torrent section topped by a horizontal rack or by a deflector beam. A physical model at the scale of 1:20 was built and granular debris flows were simulated by four successive discrete pulses. The behavior of the structure was tested inside the linear part and inside the bend of the channel reach. The geometry and dimensions of the control structure were also optimized to divert laterally a maximum volume of debris flow materials.This paper describes the physical model experiments, presents and discusses the main test results, and proposes an optimized geometry of the control structure. The most efficient configuration consists of a unilateral contract of the channel flow section inside a channel bend and to install a deflector beam
Search for emission of unstable Be clusters from hot Ca and Ni nuclei
The possible occurence of highly deformed configurations is investigated in
the Ca and Ni di-nuclear systems as formed in the Si +
C and Si + Si reactions, respectively, by using the
properties of emitted light charged particles. Inclusive as well as exclusive
data of the heavy fragments (A 6) and their associated light charged
particles (p, d, t, and -particles) have been collected at the IReS
Strasbourg VIVITRON Tandem facility with two bombarding energies
Si) = 112 and 180 MeV by using the ICARE charged particle
multidetector array, which consists of nearly 40 telescopes. The measured
energy spectra, velocity distributions, in-plane and out-of-plane angular
correlations are analysed by Monte Carlo CASCADE statistical-model calculations
using a consistent set of parameters with spin-dependent level densities.
Although significant deformation effects at high spin are needed, the remaining
disagreement observed in the Si + C reaction for the S
evaporation residue suggests an unexpected large unstable Be cluster
emission of a binary nature.Comment: 13 pages latex, 9 eps figures. Paper presented at the XXXIX
International Winter Meeting on Nuclear Physics, Bormio(Italy) January 22-27,
2001 (to be published at Ricerca Scientifica ed Educazione Permanente
Topical Peroxisome Proliferator Activated Receptor Activators Accelerate Postnatal Stratum Corneum Acidification
Previous studies have shown that pH declines from between 6 and 7 at birth to adult levels (pH 5.0â5.5) over 5â6 days in neonatal rat stratum corneum (SC). As a result, at birth, neonatal epidermis displays decreased permeability barrier homeostasis and SC integrity, improving days 5â6. We determined here whether peroxisome proliferator-activated receptor (PPAR) activators accelerate postnatal SC acidification. Topical treatment with two different PPARα activators, clofibrate and WY14643, accelerated the postnatal decline in SC surface pH, whereas treatment with PPARÎł activators did not and a PPARÎČ/ÎŽ activator had only a modest effect. Treatment with clofibrate significantly accelerated normalization of barrier function. The morphological basis for the improvement in barrier function in PPARα-treated animals includes accelerated secretion of lamellar bodies and enhanced, postsecretory processing of secreted lamellar body contents into mature lamellar membranes. Activity of ÎČ-glucocerebrosidase increased after PPARα-activator treatment. PPARα activator also improved SC integrity, which correlated with an increase in corneodesmosome density and increased desmoglein-1 content, with a decline in serine protease activity. Topical treatment of newborn animals with a PPARα activator increased secretory phospholipase A2 activity, which likely accounts for accelerated SC acidification. Thus, PPARα activators accelerate neonatal SC acidification, in parallel with improved permeability homeostasis and SC integrity/cohesion. Hence, PPARα activators might be useful to prevent or treat certain common neonatal dermatoses
- âŠ