1,721,384 research outputs found
Experimental analysis of the influence of diesel-used cooking oil methyl ester blends on efficiency, emissions and combustion process in a diesel engine
No full textAn extended investigation on the application of blends between diesel oil and used cooking oil methyl esters (UCOME) was developed on an automotive turbocharged diesel engine. Two commercial diesel oils were considered as reference fuels, the first with the conventional content of biodiesel (7%), the second with an increased amount (15%). Then, increased levels of UCOME were added, on a volumetric basis (20%, 40%, 55 or 60%), to analyze the influence of biodiesel content on engine behavior. Three part load engine operating conditions were selected for tests, measuring average engine parameters and indicated pressure diagrams. Their processing allowed to calculate the most important operating, energy and environmental engine quantities, rate of heat release and related combustion parameters. A proper management of the exhaust gas recirculation circuit, variable nozzle turbine and injection system was applied thanks to the availability of an open electronic control unit. An optimal UCOME content (40%) was identified, leading to highest values of brake thermal efficiency (with maximum increase around 5% referring to baseline fuels) and lowest levels of NOX emissions. Soot emissions were always reduced when increasing biodiesel content
Effects of rail pressure control on fuel consumption, emissions and combustion parameters in a turbocharged diesel engine
No full textThe influence of rail pressure control on fuel consumption, emissions and combustion in an automotive downsized turbocharged diesel engine was investigated, considering different operating modes in three-part load working conditions. These modes were selected according to the results of a previous step of the study, where low NOX and fuel consumption levels were obtained managing a hybrid exhaust gas recirculation (EGR) system and the turbocharger variable nozzle turbine (VNT). Aiming at limiting observed soot penalties, increased values of rail pressure were applied, deepening the interactions with engine-controlled sub-assemblies and the related variations in operating, environmental, energy and combustion parameters. At low levels of engine speed and load, major reduction in NOX emissions and fuel consumption were observed, with acceptable soot and noise combustion increase, while turbocharger speed was also enhanced. No variations in fuel consumption were achieved at higher load and speed, while soot penalty remained significant. A simplified method to describe and model engine behaviour and combustion process was also developed, defining linear relationships between rail pressure and engine quantities, including a wide set of combustion parameters derived from in-cylinder pressure diagrams and heat release curves
Metodologie Innovative per la Generazione Automatica di Pezzi Prismatici in Sistemi CAD/CAM a Due Assi
No full textMultiple positive results during a neonatal screening program: a retrospective analysis of incidence, clinical implications and outcomes
No full textAIMS: Neonatal screening programs perform different screening tests on the same blood-spot sample collected on a Guthrie card. We retrospectively investigated the incidence of multiple positive results as well as the outcomes and the physical characteristics of newborns with more than one positive result for phenylketonuria (PKU), congenital hypothyroidism (CH) and congenital adrenal hyperplasia (CAH). METHODS: Neonatal screening was performed on blood-spot for PKU (phenylalanine concentration by fluorescent ninhydrine method), for CH (simultaneous total thyroxin (tT4) and thyroid-stimulating hormone (TSH) levels by fluoroimmunometric assay); and for CAH (17-hydroxyprogesteron level by fluoroimmunometric assay). RESULTS: During three years of screening, 39 newborns (37 preterms) showed multiple positive results at screening tests (incidence 1:6387). The most frequent positive results were the combinations of CH and CAH (25/39) and PKU and CH (12/39). At recall, only two newborns were confirmed positive and each for only one disease: one, premature baby, for PKU from the PKU and CH combination; the other, born at term, for CAH from the CH and CAH combination. CONCLUSIONS: Multiple positive results are a rare observation at neonatal screening for PKU, CH and CAH, more frequently observed in preterm babies. However, multiple positive results must not be overlooked because of true positive results at recall
Neonatal screening program for inborn errors of metabolism: a retrospective study from 1978 to 1997 in Northeastern Italy
No full textAims. To assess the prevalence in northeastern Italy of various metabolic diseases (phenylketonuria, maple syrup urine disease, galactosemia, biotinidase deficiency and glucose-6-phosphate dehydrogenase deficiency) by routine neonatal screening and to compare our results with those reported for other European regions.
Methods.Between 1978 and 1997, a total of 1,142,338 newborns (≈97.1% of total births) in northeastern Italy underwent blood ampling for phenylketonuria, maple syrup urine disease and galactosemia, by absorption of the specimens onto Guthrie cards; between 1989 and 1997, a total of 509,556 newborns were screened for biotinidase deficiency. Fur-thermore, between 1982 and 1997 a total of 605,604 newborns were screened for glucose- 6-phosphate dehydrogenase deficiency solely in the Veneto region.
Results. The incidence of each disease was 1:45,690 for phenylketonuria; 1:190,390 for maple syrup urine disease; 1:40,780 for galactosemia; 1:63,690 for biotinidase deficiency and 0.24% for glucose-6-phosphate dehydrogenase deficiency.
Conclusions. The incidence for phenylketonuria and biotinidase deficiency was lower than that found in previous studies conducted in northeastern Italy. Maple syrup urine dis-ease is a rare condition in this area, as it is in the rest of Europe, although cases with a lat-er onset may not be detected by early screening. The incidence of galactosemia was sim-ilar to that reported for the rest of Europe, while the incidence of glucose-6-phosphate de- hydrogenase deficiency was lower and had a variable distribution over the territory
Growth parameters in newborns with hyperphenylalaninaemia
No full textTo understand the effects of hyperphenylalaninaemia on fetal growth, we studied growth parameters (weight, length and head circumference) of 23 phenylketonuric (PKU) and 60 hyperphenylalaninaemic (HPA) newborns from healthy mothers and of 1853 healthy neonates from north-east Italy.
A comparison of the growth parameters for both PKU and HPA newborns, as well as for controls, showed a statistically significant higher percentage of PKU and HPA patients with reduced body length and cranial circumference (P < 0.05 for both parameters in affected neonates). The z-scores for all growth parameters regarding both PKU and HPA newborns and controls, and between PKU and HPA newborns according to the Mann–Whitney non-parametric test, were statistically significantly lower in PKU newborns than in controls; in contrast, only body length was significantly lower in HPA newborns than in controls (P < 0.01). A comparison of growth parameter z-scores using the Kruskal–Wallis test for PKU, HPA and control newborns showed that both body length (P < 0.01) and cranial circumference (P < 0.05) were significantly lower in both groups of affected neonates.
Our results showed intrauterine growth retardation for both PKU and HPA newborns. Body length and cranial circumference appeared to be more important than birthweight in evaluating growth of PKU and HPA newborns
How to Best Image Colorectal Liver Metastases
No full textPurpose of Review Colorectal liver metastases affect about half of the patients with colorectal cancer and have an impact on prognosis. Resection of liver metastases, even after downstaging with chemotherapy, improves patient survival. Several imaging modalities are available for initial detection and follow-up of liver metastases. Our purpose is to review the advantages and disadvantages of each modality and to determine which is the optimal way to evaluate colorectal liver metastases in each phase of the patient's journey. Recent Findings The available evidence derives mostly from comparative studies and meta-analysis, with only few available randomized trials. MRI with DWI sequences and liver-specific contrast agents appears to be the most accurate modality for the detection of liver metastases. Different imaging modalities can be used successfully for the detection and follow-up of colorectal liver metastases, depending on the stage of the disease and patient characteristics. A stepwise approach is recommended, instead of using all modalities in each patient
Impaired Self-Awareness in Parkinson’s and Huntington’s Diseases: A Literature Review of Neuroimaging Correlates
Full text linkLittle is known about the brain correlates of anosognosia or unawareness of disease in Parkinson's Disease (PD) and Huntington's Disease (HD). The presence of unawareness or impaired self-awareness (ISA) of illness has profound implications for patients and their caregivers; therefore, studying awareness and its brain correlates should be considered a key step towards developing effective recognition and management of this symptom as it offers a window into the mechanism of self-awareness and consciousness as critical components of the human cognition. We reviewed research studies adopting MRI or other in vivo neuroimaging technique to assess brain structural and/or functional correlates of unawareness in PD and HD across different cognitive and motor domains. Studies adopting task or resting-state functional magnetic resonance imaging, and/or 18-F fluorodeoxyglucose positron emission tomography brain imaging and/or magnetic resonance imaging structural measures were considered. Only six studies investigating neuroimaging features of unawareness in PD and two in HD were identified; there was great heterogeneity in the clinical characteristics of the study participants, domain of unawareness investigated, method of unawareness assessment, and neuroimaging technique used. Nevertheless, some data converge in identifying regions of the salience and frontoparietal networks to be associated with unawareness in PD patients. In HD, the few data are affected by the variability in the severity of motor symptoms. Further studies are needed to better understand the mechanisms and brain correlates of unawareness in PD and HD; in addition, the use of dopaminergic medications should be carefully considered
Adenoma-carcinoma del retto-colon. Linee guida e criteri diagnostici minimi.
No full textIl carcinoma del retto-colon (CRC) è la terza forma tumorale per frequenza e la seconda causa di morte
per neoplasia in molti Paesi occidentali. In Italia, l'incidenza annua é stimata intorno a 20-30 mila nuovi
casi. La storia naturale è fortemente condizionata dallo stadio di malattia. Il CRC é infatti un tumore
con elevata percentuale di guarigione quando ancora limitato alla parete del viscere, mentre diventa
altamente letale, e la sua progressione poco controllabile con la terapia, quando supera i confini della
parete e metastatizza ai linfonodi.
Il CRC prende origine, in oltre il 90% dei casi, da un precursore focale, displastico, polipoide:
l'adenoma o polipo adenomatoso(19). Tale tipo di progressione tumorale, conosciuto come sequenza
adenoma-carcinoma, ha trovato riscontro e validazione clinica ed epidemiologica. Il tasso di
trasformazione maligna degli adenomi è di 2,5 adenomi per 1.000 per anno, con un tempo stimato,
particolarmente per gli adenomi <1 cm, di 10-15 anni: la tempestiva asportazione degli adenomi si è
dimostrata efficace nel ridurre l'incidenza del CRC(27). In una piccola percentuale di casi (5-10%),
soprattutto del colon destro, il carcinoma sembra non essere preceduto da lesioni polipoidi (c.d.
"carcinoma de novo").
E' acquisito che la tumorigenesi colorettale implica l'accumulo sequenziale di mutazioni di oncogeni e
di geni soppressori tumorali (Apc, Ras, DCC, MCC, p53..), eventualmente accelerato da alterazioni dei
meccanismi molecolari che normalmente controllano la stabilità del genoma (geni hMSH2, hMLH1,
hPMS1, h PMS2). Ogni evento mutazionale è in grado di orientare la storia naturale ed anche la
morfogenesi della neoplasia, sicchè alcuni di essi possono essere impiegati come marcatori prognostici
e/o essere correlati con specifiche caratteristiche morfologiche(1, 20, 25), ma le procedure di
validazione sono tutt'ora in corso e l'impiego routinario di tecniche di Patologia Molecolare
relativamente limitato
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