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 “multi tube tank”. 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 nickel‐affinity chromatography and its identity was confirmed by MALDI‐TOF 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 Allergo‐Sorbent Test (EAST). Moreover, the recombinant protein was allergenic in a biological assay as demonstrated by its capability to induce histamine release of wasp venom‐sensitive 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 8^8Be clusters from hot 40^40Ca and 56^56Ni nuclei

The possible occurence of highly deformed configurations is investigated in the $^{40}$Ca and $^{56}$Ni di-nuclear systems as formed in the $^{28}$Si + $^{12}$C and $^{28}$Si + $^{28}$Si reactions, respectively, by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments (A $\geq$ 6) and their associated light charged particles (p, d, t, and $\alpha$-particles) have been collected at the IReS Strasbourg VIVITRON Tandem facility with two bombarding energies $E_{lab}(^{28}$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 $^{28}$Si + $^{12}$C reaction for the S evaporation residue suggests an unexpected large unstable $^{8}$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

Casimir force in critical ternary polymer solutions

Consider a mixture of two incompatible polymers A and B in a common good solvent, confined between two parallel plates separated by a finite distance L. We assume that these plates strongly attract one of the two polymers close to the consolute point (critical adsorption). The plates then experience an effective force resulting from strong fluctuations of the composition. To simplify, we suppose that either plates have the same preference to attract one component (symmetric plates) or they have an opposed preference (asymmetric plates). The force is attractive for symmetric plates and repulsive for asymmetric ones. We first exactly compute the force using the blob model, and find that the attractive and repulsive forces decay similarly to L⁻⁴. To go beyond the blob model that is a mean-field theory, and in order to get a correct induced force, we apply the Renormalization-Group to a φ⁴ -field theory ( φ is the composition fluctuation), with two suitable boundary conditions at the surfaces. The main result is that the expected force is the sum of two contributions. The first one is the mean-field contribution decaying as L⁻⁴, and the second one is the force deviation originating from strong fluctuations of the composition that decreases rather as L⁻³. This implies the existence of some cross-over distance L* ∼ aNφ¹/² ( a is the monomer size, N is the polymerization degree of chains and φ is the monomer volumic fraction), which separates two distance-regimes. For small distances (L L*) the fluctuation force is more important.Розглядається суміш двох несумісних полімерів A і B , що добре розчиняються в спільному розчиннику, вміщена між двома паралельними пластинами, розділеними скінченною відстанню L. Ми вважаємо, що поблизу точки розчинення вони сильно притягають один з двох полімерів (критична адсорбція). При цьому пластини знаходяться під впливом ефективної сили, породженої сильними флуктуаціями суміші. Для спрощення ми припускаємо, що або обидві пластини притягають той самий компонент (симетричні пластини) або вони віддають перевагу різним компонентам (асиметричні пластини). Симетричним пластинам відповідає сила притягання, асиметричним – відштовхування. Спершу ми точно розрахували цю силу, використовуючи краплинну модель, і встановили, що сили притягання і відштовхування загасають подібним чином як L⁻⁴. Щоб вийти поза межі краплинної моделі, яка відповідає наближенню середнього поля, і з метою отримати правильний вигляд індукованої сили, ми застосували ренорм-груповий підхід до теорії поля φ⁴ ( φ – флуктуація суміші) з двома відповідними граничними умовами на поверхнях. У результаті встановлено, що шукана сила є сумою двох вкладів. Перший з них – це вклад середнього поля, що загасає якL⁻⁴, а другий – відхилення, викликане сильними флуктуаціями суміші, що зменшується радше як L⁻³. Це означає, що існує певна відстань кроссоверу L* ∼ aNφ¹/² ( a – розмір мономера, N – ступінь полімеризації ланцюжків і φ – об’ємна частка мономера), що розділяє характерні відстані двох згаданих режимів. На малих відстанях (L L*) більш важливим стає флуктуаційний вклад