34 research outputs found

    EXPERIMENTAL ANALYSIS OF THE TRANSIENT BEHAVIOR OF AN ENGINE COOLING RADIATOR

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    The aim of this work is to study the behavior of an engine cooling radiator in a transient state, with circulation of heated water. An experimental apparatus was constructed with the radiator inside a wind tunnel. The water is pumped from a small water tank to a heater, passes through the heat exchanger, and returns to the tank. The tests were carried out with constant flowrates of water and air, and the heater was turned on and then off according to a pulse function. The temperatures of the radiator, the air and the water were measured on several points with thermocouples and a thermal camera. The flow of water and air were measured as well. A fast dynamics because of the radiator was observed, whereas a slow one was noticed due to water heating in the tank. The steady state was reached after 15 min. These results might be useful in the project of a vehicle cooling system under transient conditions

    FMRP regulates presynaptic localization of neuronal voltage gated calcium channels

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    Fragile X syndrome (FXS), the most common form of inherited intellectual disability and autism, results from the loss of fragile X mental retardation protein (FMRP). We have recently identified a direct interaction of FMRP with voltage-gated Ca2+ channels that modulates neurotransmitter release. In the present study we used a combination of optophysiological tools to investigate the impact of FMRP on the targeting of voltage-gated Ca2+ channels to the active zones in neuronal presynaptic terminals. We monitored Ca2+ transients at synaptic boutons of dorsal root ganglion (DRG) neurons using the genetically-encoded Ca2+ indicator GCaMP6f tagged to synaptophysin. We show that knock-down of FMRP induces an increase of the amplitude of the Ca2+ transient in functionally-releasing presynaptic terminals, and that this effect is due to an increase of N-type Ca2+ channel contribution to the total Ca2+ transient. Dynamic regulation of CaV2.2 channel trafficking is key to the function of these channels in neurons. Using a CaV2.2 construct with an α-bungarotoxin binding site tag, we further investigate the impact of FMRP on the trafficking of CaV2.2 channels. We show that forward trafficking of CaV2.2 channels from the endoplasmic reticulum to the plasma membrane is reduced when co-expressed with FMRP. Altogether our data reveal a critical role of FMRP on localization of CaV channels to the presynaptic terminals and how its defect in a context of FXS can profoundly affect synaptic transmission

    ANALYSIS AND OPTIMIZATION OF OPERATIONAL CONDITIONS OF A PACKED BED REACTOR FOR FISCHER-TROPSCH SYNTHESIS

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    Due to the depleting of non-renewable fuel sources, a lot of academic and industrial effort has been made in the search for alternative routes. In this context, Fischer-Tropsch synthesis represents one possible solution. The goal of this work is the study of operational conditions involved in this synthesis, in a packed bed reactor. In this analysis, the system was modelled by taking into account material and energy balances, and kinetic laws and pressure drop in the reactor bed as well. The resulting ordinary differential equations were solved and evaluated in Matlab and operational conditions in the reactor were mapped. Gasoline yield and selectivity were analyzed and optimized through changes in the cooling system of the equipment. In the best operational conditions, gasoline yield was equal to 8 g / 100 g, which is really a good result when compared to pilot plant’s data published in the literatur

    Multicenter prospective study on the prevalence of colistin resistance in Escherichia coli: relevance of mcr-1-positive clinical isolates in Lombardy, Northern Italy

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    Luigi Principe,1 Aurora Piazza,2,3 Carola Mauri,1 Adriano Anesi,4 Silvia Bracco,5 Gioconda Brigante,6 Erminia Casari,7 Carlo Agrappi,8 Mariasofia Caltagirone,2 Federica Novazzi,2 Roberta Migliavacca,2 Laura Pagani,2 Francesco Luzzaro1 1Microbiology and Virology Unit, A. Manzoni Hospital, Lecco, Italy; 2Clinical-Surgical, Diagnostic and Pediatric Sciences Department, Unit of Microbiology and Clinical Microbiology, University of Pavia, Pavia, Italy; 3Romeo and Enrica Invernizzi Pediatric Research Center, Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy; 4Clinical Pathology Laboratory, ASST Lodi, Lodi, Italy; 5Clinical Pathology Laboratory, ASST Vimercate, Vimercate, Italy; 6Clinical Pathology Laboratory, ASST Valle Olona, Busto Arsizio, Italy; 7Clinical Pathology Laboratory, IRCCS “Humanitas,” Rozzano, Italy; 8Microbiology and Virology Unit, ASST Ovest Milanese, Legnano, Italy Background: The emergence of the plasmid-mediated colistin resistance mechanism in Escherichia coli has raised concern among public health experts as colistin is a last-line antimicrobial resort. The primary aim of the study was to investigate the prevalence of this resistance trait in E. coli isolates circulating in the Lombardy region, Northern Italy. The presence of mcr-type genes and their genetic relationship were also studied.Materials and methods: A prospective study was performed during a 4-month period (May to August, 2016) in six acute care Hospitals. Consecutive nonduplicate clinical isolates of E. coli from any type of clinical specimen, with the exception of rectal swabs, were included in the study. Isolates that exhibited MIC values for colistin >2 mg/L were further investigated. Bacterial identification was obtained by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Amplification of mcr-type genes (−1 to −5 variants) and microarray analysis were accomplished. Repetitive sequence-based PCR (Rep-PCR) and multilocus sequence typing (MLST) analysis were used for genotyping.Results: Overall, 3,902 consecutive E. coli isolates (2,342 from outpatients, 1,560 from inpatients) were evaluated during the study period. Of them, 18/3,902 (0.5%), collected from 4/6 centers, showed resistance to colistin. These isolates were mostly obtained from urine of both outpatients (n=12) and inpatients (n=6). Colistin MIC values ranged from 4 to 8 mg/L. The mcr-1 gene was detected in 10/18 isolates (7 from outpatients, 3 from inpatients). Rep-PCR and MLST analysis revealed the presence of nine different clusters. Further mcr-type genes were not detected.Conclusion: Resistance to colistin in E. coli clinical isolates appears low in our geographic area. With regard to mcr-1-positive isolates, they accounted for approximately 50% of colistin-resistant E. coli isolates, thus representing a relevant resistance mechanism in this context. Although overall limited, the presence of mcr-1 determinant in our region should not be ignored and great concern should be given to the continuous surveillance. Keywords: MCR-1, colistin, Escherichia coli, prevalence, surveillance, epidemiolog

    Genomic epidemiology of SARS-CoV-2 reveals multiple lineages and early spread of SARS-CoV-2 infections in Lombardy, Italy

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    From February to April 2020, Lombardy (Italy) reported the highest numbers of SARS-CoV-2 cases worldwide. By analyzing 346 whole SARS-CoV-2 genomes, we demonstrate the presence of seven viral lineages in Lombardy, frequently sustained by local transmission chains and at least two likely to have originated in Italy. Six single nucleotide polymorphisms (five of them non-synonymous) characterized the SARS-CoV-2 sequences, none of them affecting N-glycosylation sites. The seven lineages, and the presence of local transmission clusters within three of them, revealed that sustained community transmission was underway before the first COVID-19 case had been detected in Lombardy

    Rapid and sensitive detection of SARS-CoV-2 RNA using the Simplexa\u2122 COVID-19 direct assay

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    Background: So far, one of the major drawbacks of the available molecular assays for the diagnosis of severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) is the need for viral nucleic acid extraction from clinical specimens. Objective: The aim of this study was to evaluate the performances of a newly designed real-time RT-PCR (Simplexa\u2122 COVID-19 Direct assay), that is established with an all-in-one reagent mix and no separate extraction required. Results: The lower limit of detection (LOD) for both target genes resulted the same: 3.2 (CI: 2.9\u20133.8) log10 cp/mL and 0.40 (CI: 0.2\u20131.5) TCID50/mL for S gene while 3.2 log10 (CI: 2.9\u20133.7) log10 cp/mL and 0.4 (CI: 0.2\u20131.3) TCID50/mL for ORF1ab. The LOD obtained with extracted viral RNA for both S gene or ORF1ab was 2.7 log10 cp/mL. Crossreactive analysis performed in 20 nasopharyngeal swabs confirmed a 100% of clinical specificity of the assay. Clinical performances of Simplexa\u2122 COVID-19 Direct assay were assessed in 278 nasopharyngeal swabs tested in parallel with Corman's method. Concordance analysis showed an \u201calmost perfect\u201d agreement in SARS-CoV-2 RNA detection between the two assays, being \u3ba = 0.938; SE = 0.021; 95% CI = 0.896-0.980. Conclusions: The high sensitivity and specificity of this new assay indicate that it is promising for laboratory diagnosis, enabling highspeed detection in just over one hour, which is significantly faster than the up to five hours currently required by traditional extraction followed by amplification technologies, thus allowing prompt decision making regarding isolation of infected patients
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