504 research outputs found
CFD-3D Analysis of a Light Duty Dual Fuel (Diesel/Natural Gas) Combustion Engine
AbstractNowadays, the most critical issues concerning internal combustion engines are the reduction of the pollutant emissions, in particular of CO2, and the replacement of fossil fuels with renewable sources. An interesting proposition for Diesel engines is the Dual Fuel (DF) combustion, consisting in the ignition of a premixed charge of gaseous fuel (typically natural gas) by means of a pilot injection of Diesel Fuel.Dual fuel combustion is a quite complex process to model, since it includes the injection of liquid fuel, superimposed with a premixed combustion. However, CFD simulation is fundamental to address a number of practical issues, such as the setting of the liquid injection parameters and of the gaseous fuel metering, as well as to get the maximum benefit from the DF technique.In this paper, a customized version of the KIVA-3V Computational Fluid Dynamic (CFD) code was adopted to analyze the combustion process of a 4-cylinder, 2.8 l, turbocharged HSDI Diesel engine, operating in both Diesel and DF (Diesel and Natural Gas) modes.Starting from a previously validated diesel combustion model, a natural gas combustion model was implemented and added to simulate the DF operations. Available engine test data were used for validation of the diesel-only operation regimes. Using the calibrated model, the influence of the premixed charge composition was investigated, along with the effect of the diesel injection advance angle, at a few characteristic operating conditions. An optimum setting was eventually found, allowing the DF engine to deliver the same brake power of the original Diesel unit, yielding the same maximum in-cylinder pressure.It was found that DF combustion is soot-less, yields a strong reduction of CO and CO2, but also an increase of NO
Let-7c down-regulation in Helicobacter pylori-related gastric carcinogenesis
open12siAberrant let-7c microRNA (miRNA) expression has been observed in Helicobacter pylori-related gastric cancer (GC) but fragmentary information is available on the let-7c dysregulation occurring with each phenotypic change involved in gastric carcinogenesis. Let-7c expression was assessed (qRT-PCR) in a series of 175 gastric biopsy samples representative of the whole spectrum of phenotypic changes involved in H. pylori-related gastric oncogenesis including: i) normal gastric mucosa, as obtained from dyspeptic controls (40 biopsy samples); ii) non-atrophic gastritis (40 samples); iii) atrophic-metaplastic gastritis (35 samples); iv) intra-epithelial neoplasia (30 samples); v) GC (30 samples). Let-7c expression was also tested in 20 biopsy samples obtained from 10 patients before and after H. pylori eradication therapy (median follow-up: 10 weeks; range: 7-14). The results obtained were further validated by in situ hybridization on multiple tissue specimens obtained from 5 surgically treated H. pylori-related GCs. The study also included 40 oxyntic biopsy samples obtained from serologically/histologically confirmed autoimmune gastritis (AIG: 20 corpus-restricted, non-atrophic; 20 corpus-restricted, atrophic-metaplastic). Let-7c expression dropped from non-atrophic gastritis to atrophic-metaplastic gastritis, intra-epithelial neoplasia, and invasive GC (p<0.001). It rose again significantly following H. pylori eradication (p=0.009). As in the H. pylori model, AIG also featured a significant let-7c down-regulation (p<0.001). The earliest phases of the two pathways to gastric oncogenesis (H. pylori-environmental and autoimmune host-related) are characterized by similar let-7c dysregulations. In H. pylori infection, let-7c down-regulation regresses after the bacterium's eradication, while it progresses significantly with the increasing severity of the histological lesions.openFassan, Matteo; Saraggi, Deborah; Balsamo, Laura; Cascione, Luciano; Castoro, Carlo; Coati, Irene; DE BERNARD, Marina; Farinati, Fabio; Guzzardo, Vincenza; Valeri, Nicola; Zambon, CARLO-FEDERICO; Rugge, MassimoFassan, Matteo; Saraggi, Deborah; Balsamo, Laura; Cascione, Luciano; Castoro, Carlo; Coati, Irene; DE BERNARD, Marina; Farinati, Fabio; Guzzardo, Vincenza; Valeri, Nicola; Zambon, CARLO-FEDERICO; Rugge, Massim
Role of interface and morphology in the magnetic behaviour of perpendicular thin films based on L10 FePt
FePt L10 ordered alloy is a promising material for high-density magnetic recording, since it allows the ferromagnetic stability in particles of few nanometers. Here we present our recent studies on the correlation between magnetic and morphological/interfacial properties of FePt -based thin films, nanostructures, and nano-composite bilayers. L10 FePt (001) epitaxial thin films with high structural quality were grown on (100) MgO by sputtering r.f., using the alternate-layer deposition method. By playing with growth temperature on the one hand and post-annealing temperature and time on the other, we have been able to finely control epitaxy, structural order, and morphology from 3D laterally confined structures to continuous film, with desired grain size. In particular we have been able to decrease grain size and to optimise magnetic properties (increase of anisotropy/coercivity ratio) at the same time, by post-annealing in situ [1]. Laterally confined magnetic structures were also obtained by focused ion beam (FIB). We have shown that for suitable Ga+ doses (1?1014 ion/cm2), it is possible to transform the L10 ordered phase to the A1 disordered one, without affecting morphology, giving rise to substantial modifications of magnetic properties from hard to soft. Perpendicular 2D magnetic patterns (dots, stripes) in a soft easy-plane matrix were realized in films of continuous morphology [2]. FePt L10 has also been exploited as the hard layer of nanostructured hard-soft nanocomposite bilayers. The exploitation of the exchange-coupling between hard and soft layers in exchange-coupled media represents a possible approach to overcome the so-called "recording trilemma" [3]. The samples were prepared by growing a magnetically soft Fe layer (2 and 3.5 nm) over a hard FePt(001) layer (10 nm). Three bilayers series have been grown based on FePt epitaxial layers with high degree of chemical order (S≥0.76) and different morphologies, corresponding to different interface characteristics. The resulting hard layer anisotropy is high (K>1?107 erg/cm3), and the coercivity is increased by the grains separation (from 1.7 to 3 T). In the Fe/FePt bilayers the coercivity HC is strongly reduced compared to the hard layer value (HC/HChard down to 0.37), indicating that high anisotropy perpendicular systems with moderate coercivity can be obtained [4]. Moreover, the control of the interface morphology allows to modify the magnetic regime at fixed Fe thickness (Rigid Magnet to Exchange-Spring), due to the nanoscale structure effect on the hard/soft coupling, and to tailor the hysteresis loop characteristics
The Role of Laparoscopy in the Management of a Diagnostic Dilemma: Jejunal Ectopic Pancreas Developing into Jejunojejunal Intussusception
Ectopic pancreas (EP) is a rare congenital anomaly defined as the presence of pancreatic tissue in topographic anomaly. It is usually silent but it may become clinically evident when complicated by acute conditions. The development of laparoscopic surgery has changed the way to manage such conditions, especially in the setting of emergency surgery, thanks to its diagnostic and therapeutic role with excellent results. We decided to perform an emergency diagnostic exploratory laparoscopy in a 29-year-old man with an acute abdomen and nonspecific radiological images for intestinal occlusion. A jejunojejunal intussusception was found, caused by a mass. We decided to carry out minilaparotomy to perform a resection of the affected jejunum. Histological examination confirmed the presence of a jejunal ectopic pancreas. Adult intussusception caused by EP represents 5% of all cases of intussusception. As CT scan, especially when performed in emergency setting for small bowel obstruction diagnosis, can usually demonstrate nondiagnostic findings suggestive of intussusception of unknown origin, laparoscopic exploration could help surgeons in order to perform a resolute diagnosis and treat the pathology
Smartphone addiction through age and gender during Italian lockdown for COVID-19
Background: Nomophobia (no-mobile-phobia or Disconnection Syndrome) is the fear of not being able to consult your mobile phone, not being connected or traceable. This is an addiction to excessive smartphone usage related to the constant need to consult it to view notifications and updates. Like other forms of addiction, nomophobia is associated with excessive behaviors that lead to an increasing use of the phone to the point where it cannot do without it and the need to take it with it to any place or circumstance. The fear of not being connected consequently evokes reactions of excessive anxiety with specific physiological related (e.g., breathlessness, sweating, tremor, heart acceleration, sweating etc.). Nomophobia, however, is not included in anxiety disorders but is part of the pathological addictions to which it responds adequately. In fact, there are many behavioral and emotional analogies with other forms of addiction (including gambling) so the hypothesis that the abuse of the smartphone should be categorized as a real addiction can be accepted. The dependencies associated with the Internet and technologies that can be defined Dependencies 2.0, include the smartphone. During the Italian lockdown caused by COVID-19, the use of technologies has been the fundamental basis of adaptation for smart working, school and professional training, which has led to a change in the population lifestyle. Objective: The purpose of this work is to document the level of smartphone dependence that has occurred during the COVID-19 lockdown period. Material and Methods: The NoMobilePhobia-Questionnaire (NMP-Q) was presented online to 1264 participants between the ages of 15 and 60. With regard to the selection of participants, approximately between the ages of 15 and 60, we used the method of random numbers: in fact, one participant for every hundred inhabitants was chosen in a randomized way. Finally, it was necessary for all participants to have access to the Internet. These dynamics have been acquitted in order to give us a valid representative sample. Results: The results show no significant main effects for the two factors taken into account (Gender and Age of participants). However the significant interaction shows that female participants reported on average higher scores on NoMobilePhobia-Questionnaire (NMP-Q) than males , for the younger age group (15 to 44), while for those over the age of 44, the average highest scores were for male participants. The main effects of the "Sex" factor [F(1,1256)= 3.179 and p=0.75] and "Age_class" [F(4,1253)=1.82 and p=0.12] are not significant; the interaction between the Sex-Age_class factors is significant with F(4,1253) =7.06 and p<.001 and an observed power close to 1 (0.99). The correlation between the Variable "Score" and the measure of the "Age" was found to be significant (negative) linear relationship (r of Pearson =-.093 and p<.001) considering the whole sample. Conclusions: One of the "positive" aspects of the COVID-19 pandemic is the use of the Internet and smartphones, and our analysis aimed to document the frequency of use in the Italian context with the NoMobilePhobia-Questionnaire. The results reveal the risk in some parts of the Italian population to develop forms of smartphone dependence, especially in circumstances that prohibit direct social interactions
MicroRNA-135b promotes cancer progression by acting as a downstream effector of oncogenic pathways in colon cancer
MicroRNA deregulation is frequent in human colorectal cancers (CRCs), but little is known as to whether it represents a bystander event or actually drives tumor progression in vivo. We show that miR-135b overexpression is triggered in mice and humans by APC loss, PTEN/PI3K pathway deregulation, and SRC overexpression and promotes tumor transformation and progression. We show that miR-135b upregulation is common in sporadic and inflammatory bowel disease-associated human CRCs and correlates with tumor stage and poor clinical outcome. Inhibition of miR-135b in CRC mouse models reduces tumor growth by controlling genes involved in proliferation, invasion, and apoptosis. We identify miR-135b as a key downsteam effector of oncogenic pathways and a potential target for CRC treatment
The Case for a Muon Collider Higgs Factory
We propose the construction of a compact Muon Collider Higgs Factory. Such a
machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean
Higgs events per year, enabling the most precise possible measurement of the
mass, width and Higgs-Yukawa coupling constants.Comment: Supporting letter for the document: "Muon Collider Higgs Factory for
Smowmass 2013", A White Paper submitted to the 2013 U.S. Community Summer
Study of the Division of Particles and Fields of the American Physical
Society, Y. Alexahin, et. al, FERMILAB-CONF-13-245-T (July, 2013
MIR21 drives resistance to Heat Shock Protein 90 inhibition in cholangiocarcinoma
Cholangiocarcinomas (CCA) are resistant to chemotherapy, so new therapeutic agents are needed. We performed a screen to identify small molecule compounds that are active against CCAs. Levels of microRNA 21 (MIR21 or miRNA21) are increased in CCAs. We investigated whether miRNA21 mediates resistance of CCA cells and organoids to HSP90 inhibitors
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