149 research outputs found

    Correction to: Fire spalling sensitivity of high-performance concrete in heated slabs under biaxial compressive loading

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    The article ''Fire spalling sensitivity of high-performance concrete in heated slabs under biaxial compressive loading'', written by "Francesco Lo Monte, Roberto Felicetti, Chiara Rossino", was originally published electronically on the publisher's Internet portal (currently SpringerLink) on 25 January 2019 without open access

    A Comprehensive Forward Model for Imaging under Irregular Terrain Using RF Tomography

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    Imaging of tunnel networks under irregular terrain using RF tomography is generalized to include the possibility of magnetic dipoles (i.e., electric loops) either as transmitting or receiving devices. Forward scattering models are presented, and a generalized method for computing numerical dyadic Green’s functions is detailed. Explicit formulas for fast numerical implementation are also presented. The paper is corroborated with numerical simulations aimed at validating formulas

    Experimental Study on the Explosive Spalling in High-Performance Concrete: Role of Aggregate and Fiber Types

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    A complete description of the mechanical behavior of High-Performance Concrete in fire still requires further efforts to fully understand the tricky phenomenon of spalling, whose complexity comes from the interaction among different phenomena, namely: the microstructural changes occurring in concrete at high temperature, the pressure rising in the pores, and the stress induced by both thermal gradients and external loads. To what extent these different aspects influence each other is still not completely clear, and within this context a comprehensive experimental campaign has been launched at the Politecnico di Milano, focusing on the role played by concrete grade, aggregate type, and fiber type and content. Eleven concrete mixes are investigated considering three grades (fc ≥ 40, 60 and 90 MPa), three aggregate types (silico-calcareous, basalt and calcareous aggregates) and different fiber types and contents (steel and monofilament or fibrillated polypropylene fibers)

    Fatigue Characterization Of A High-Performance Steel Fiber Reinforced Concrete (HPFRC) By Means Of Compressive, Flexural, And Z-Type Shear Tests

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    The use of fiber-reinforced concretes (FRC) for infrastructures subject to fatigue loading can result into an extension of their service life by providing enhanced ductility and toughness. The cyclic actions might affect the fiber-matrix interface and it is necessary to assess to what extent the degradation hinders the mechanical properties of these materials. Currently, the only predictive models for fatigue life and performance reduction are empirical. Therefore, a mechanical characterization is required for any mix whose composition and performance might differ from the one pertinent to the database the models are based on. This work presents the effect of high-cycle fatigue on a high-performance fiber-reinforced concrete (HPFRC) with hybrid fiber reinforcement. The material was characterized under compressive, flexural, and shear loads at various stress ranges. The Palmgren-Miner rule was applied to predict the fatigue life of the material. The results showed the effects of fatigue loading on the strength of the material. The compressive strength remained constant in most cases, while the flexural and the shear performances were slightly reduced by the cycling process. The predictive capacity of the P-M model proved to be reliable only in limited scenarios

    Simple and fast orotracheal intubation procedure in rat

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    Introduction: Endotracheal intubation in the rat is difficult because of extremely small size of anatomical structures (oral cavity, epiglottis and vocal cords), small inlet for an endotracheal tube and the lack of proper techniacal instruments. Matherial and Methods: In this study we used seventy rats weighthing 400-500 g. The equipment needed for intubation was an operating table, a longish of cotton, a cotton tip, orotracheal tube, neonatal laryngoscope KTR4, small animal ventilator, and isoflurane for inhalation anaesthesia. Premedication was carried out by medetomidine hydrochloride 1 mg/mL; then, thanks to a closed glass chamber, a mixture of oxygen and isoflurane was administered. By means of neonatal laryngoscope the orotracheal tube was advanced into the oral cavity untile the wire guide was visualized trough the vocal cords; then it was passed through them. The tube was introduced directly into into the larynx over the wire guide; successively, the guide was removed and the tube placed into the trachea. Breathing was confirmed using a glove, cut at the end of a finger, simulating a small ballon. Conclusions: We believe that our procedure is easier and faster than those previously reported in scientific literature. (www.actabiomedica.it

    Is secondary hyperparathyroidism-related myelofibrosis a negative prognostic factor for kidney transplant outcome?

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    Secondary hyperparathyroidism (HP) presenting with hypocalcemia and subsequent increased parathormone (PTH), is mainly identified in patients with chronic renal failure, which has been associated with variable degrees of bone marrow fibrosis. For suitable patients with end-stage renal disease (ESRD), kidney transplantation is recognized as the therapy of choice, being superior to dialysis in terms of quality of life and long-term mortality risk; in this regard interesting data show that increased time on dialysis prior to kidney transplantation is associated with decreased graft and patient survival. In our opinion an important and until now underestimated determinant of graft survival is the proper activity of bone marrow because of the emerging role of hematopoietic stem cells (HSC) in repair of ischemia/reperfusion (IR) damage. We postulate that in ESRD patients, who usually undergo long dialytic treatment, a myelofibrosis caused by an overt secondary HP could drastically decrease the HSC potential for IR damage repair after kidney transplant; this could irremediably lead to a delay in graft function with all related complicances. If the curative role of bone marrow-derived stem cells was confirmed by more data obtained in experimental animal models, it could be possible to try a cellular-based therapeutic approach in the management of ESRD patients which are in waiting list for a kidney transplant

    Organismi geneticamente modificati: definizioni e finalità.

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    Article 2 of the European Directive 2011/18/EC defines a genetically modified organism (GMO) a san organism in which the genetic material has been altered in a way that does not occuirr naturally by inserting DNA fragments from one organism's gene into the chromosomes of another, changing its genetic expression. In the field of animal and plants biotechnology there are different application areas of genetic engineering such as improving the quantity and quality of argicultural production, pharmaceutical production in more sustainable ways or applications in environmental field

    THE MEDITERRANEAN DIET: A HISTORY OF HEALTH

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    The Mediterranean tradition offers a cousine rich in colors, aromas and memories, which support the taste and the spirit of those who live in harmony with nature. Everyone is talking about the Mediterranean diet, but few are those who do it properly, thus generating a lot of confusion in the reader. And so for some it coincides with the pizza, others identified it with the noodles with meat sauce, in a mixture of pseudo historical traditions and folklore that do not help to solve the question that is at the basis of any diet: combine and balance the food so as to satisfy the qualitative and quantitative needs of an individual and in a sense, preserves his health through the use of substances that help the body to perform normal vital functions. The purpose of our work is to demonstrate that the combination of taste and health is a goal that can be absolutely carried out by everybody, despite those who believe that only a generous caloric intake can guarantee the goodness of a dish and the satisfaction of the consumers. That should not be an absolute novelty, since the sound traditions of the Mediterranean cuisine we have used for some time in a wide variety of tasty gastronomic choices, from inviting colors and strong scents and absolutely in line with health

    INFLAMMATORY BOWEL DISEASE (IBD) IN PREGNANCY: ANALYSIS OF THE POSSIBLE EFFECTS OF THE DISEASE ON THE FETUS AND THE NEWBORN AND THERAPEUTIC APPROACHES

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    The Inflammatory Bowel Diseases(IBD), are a group of inflammatory diseases characterized by the presence of chronic inflammation, i the absenc of infectious ethiology. The two most well-known diseases in this group are: Crohn's disease (CD) and Ulcerative Colitis (UC). In cases where iti is not possible to distinguish between CD and UC, it is called Indeterminated Colitis. IBD can affect women pregnant. The causes of IBD are unknown, and the clinical course of the sdisease is characterized by phases of activity and remission. UC is a chronic inflammation of the mucosa of the colon and involving predominantly the left colon and rectum. It is associatred with presence of blood and mucus in the stool, diarrhea and anemia. characteristically, CD involves entire mgastrointestinal tract, from the mouth to the anus. In CD, the inflammatory infiltrate involves the entire intestinal wall. Clinically manifested by abdominal pain, diarrhea, loss of appetite and weight loss. The complications are stenosis, fistulas, abscesses, and perianal involvement. In IBD TNF_alpha and proinflammatory cytokines are overexpressed. The analysis of the scientific literature shows that fertility, in pregant women suffering from IBD, is preserved. It shows slightly reduced for CD and ileo-anal pouch. Women with active disease at the time of conception have an increased risk of spontaneous abortion, preterm birth, with low birth weight and congenital malformations of the fetus. The indications for surgical treatment are the same as for non-pregnant women. The inactive disease or ileo-anal pouch is not a contraindication to spontaneous vaginal delivery, as is happens in the case of active colitis or perirectal fistulas or rectovaginal fistulas. Safe drug during pregnancy are: 5-aminosalicylic acid (5-ASA), steroids, 6-Mercaptopurine (&MP), Atatioprine (AZA) and Infliximab. Contraindicateddrugs are Metrotrexate and Thalidomide. In conclusion, the expectations about pregnancy, in women affected of IBD, is similar to the general population, especiually if the conception occurs in inactive phase of the disease

    INFLAMMATION IN IRRITABLE BOWEL SYNDROME: MYTH OR NEW TREATMENT TARGET?

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    Low-grade intestinal inflammation plays a key role in the pathophysiology of irritable bowel syndrome (IBS), and this role is likely to be multifactorial. The aim of this review was to summarize the evidence on the spectrum of mucosal inflammation in IBS, highlighting the relationship of this inflammation to the pathophysiology of IBS and its connection to clinical practice. We carried out a bibliographic search in Medline and the Cochrane Library for the period of January 1966 to December 2014, focusing on publications decribing an interaction between inflammation and IBS. Several evidences demonstrate microscopic and molecular abnormalities in IBS patients. Understanding the mechanism underlying low-grade inflammation in IBS may help to design clinical trials to test the efficacy and safety of drugs that target this pathophysiologic mechanism
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