210 research outputs found
A collimation system for ELI-NP Gamma Beam System - design and simulation of performance
The purpose of this study was to evaluate the performance and refine the design of the collimation system for the gamma radiation source (GBS) currently being realised at ELI-NP facility. The gamma beam, produced by inverse Compton scattering, will provide a tunable average energy in the range between 0.2 and 20 MeV, an energy bandwidth 0.5% and a flux of about 108 photons/s. As a result of the inverse Compton interaction, the energy of the emitted radiation is related to the emission angle, it is maximum in the backscattering direction and decreases as the angle increase [1,2]. Therefore, the required energy bandwidth can be obtained only by developing a specific collimation system of the gamma beam, i.e. filtering out the radiation emitted at larger angles. The angular acceptance of the collimation for ELI-NP-GBS must be continuously adjustable in a range from about 700 to 60 μrad, to obtain the required parameters in the entire energy range. The solution identified is a stack of adjustable slits, arranged with a relative rotation around the beam axis to obtain an hole with an approximately circular shape. In this contribution, the final collimation design and its performance evaluated by carrying out a series of detailed Geant4 simulations both of the high-energy and the low-energy beamline are presented
Quadrupole scan emittance measurements for the ELI-NP compton gamma source
The high brightness electron LINAC of the Compton
Gamma Source at the ELI Nuclear Physics facility in Roma-
nia is accelerating a train of 32 bunches with a nominal total
charge of
250 pC
and nominal spacing of
16 ns
. To achieve
the design gamma flux, all the bunches along the train must
have the designed Twiss parameters. Beam sizes are mea-
sured with optical transition radiation monitors, allowing a
quadrupole scan for Twiss parameters measurements. Since
focusing the whole bunch train on the screen may lead to
permanent screen damage, we investigate non-conventional
scans such as scans around a maximum of the beam size
or scans with a controlled minimum spot size. This paper
discusses the implementation issues of such a technique in
the actual machine layou
Late effects of chemotherapy and radiotherapy in osteosarcoma and Ewing sarcoma patients: The Italian Sarcoma Group Experience (1983-2006)
Gallium(III)-pyridoxal thiosemicarbazone derivatives as nontoxic agents against Gram-negative bacteria
Many bacterial strains are developing mechanism of resistance to antibiotics, rendering last-resort antibiotics inactive. Therefore, new drugs are needed and in particular metal-based compounds represent a valid starting point to explore new antibiotic classes. In this study, we have chosen to investigate gallium(III) complexes for their potential antimicrobial activity against different strains of Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa which have developed different type of resistance mechanism, including the expression of beta-lactamases (NDM-1, ES beta L, or AmpC) or the production of biofilm. We studied a series of thiosemicarbabazones derived from pyridoxal, their related Ga(III) complexes, and the speciation in solution of the Ga(III)/ligand systems as a function of the pH. Proton dissociation constants and conditional stability constants of Ga(III) complexes were evaluated by UV/Vis spectroscopy, and the most relevant species at physiological pH were identified. The compounds are active against resistant Gram-negative strain with minimal inhibitory concentration in the mu M range, while no cytotoxicity was detected in eukaryotic cells
Sclerosing Angiomatoid Nodular Transformation of the Adrenal Gland: A Case Report of a Novel Histopathological Entity
The finding of an indeterminate adrenal mass at radiological investigations is a challenge for physicians. Complex diagnostic work-up, periodic follow-up, or surgical intervention are therefore needed to rule out malignant lesions. Tertiary care hospitals are provided with F-18-fludeoxyglucose (F-18-FDG) positron emission tomography (PET) and F-18-dihydroxyphenylalanine (F-18-DOPA) PET, which aid in the characterization of indeterminate adrenal masses. Nevertheless, the histopathological examination may be required to exclude malignancy or rare etiologies. A 54-year-old woman presented to our clinic 6 months after a cerebral hemorrhage. She was hypertensive and had recently discovered a left adrenal mass of 15 mm during an abdominal ultrasound. Contrast-enhanced CT, following adrenal protocol, revealed a 14-mm adrenal mass without characteristics suggestive of an adrenal adenoma. Tumor markers were negative. Functional tests excluded hormone hypersecretion. An F-18-DOPA PET was negative. An F-18-FDG PET showed mild uptake of both the adrenal glands, with a more circumscribed pattern in the left one (maximum standardized uptake value 5 4). As the clinical diagnosis was still indeterminate, we performed laparoscopic left adrenalectomy. The histopathological examination described a sclerosing angiomatoid nodular transformation (SANT) of the adrenal gland, a benign lesion already described as a rare occurrence only in the spleen. IgG4 levels were reduced. In conclusion, this is a report of a SANT of the adrenal gland, a novel entity that should be taken into consideration in the differential diagnosis of indeterminate adrenal masses at CT scan. Copyright (C) 2019 Endocrine Societ
Shiga toxin-producing Escherichia coli O157, O26 and O111 in cattle faeces and hides in Italy
Introduction: Ruminants are regarded as the natural
reservoir for Shiga toxin-producing Escherichia coli
(STEC), especially of serogroup O157.
Materials and methods: During 2011 and 2012,
320 samples (160 faecal samples from the rectum and
160 hide samples from the brisket area) were collected
from 160 cattle at slaughter in Northern Italy during
warm months (May to October). Cattle were reared in
different farms and their age at slaughter ranged
between nine months and 15 years, most of them
being culled cattle (median age: six years; average age:
4.6 years). Samples were tested by immunomagneticseparation
technique for E coli O157 and O26 and by a
screening PCR for stx genes followed by cultural
detection of STEC. The virulence genes stx1, stx2, eae,
and e-hlyA were detected and among stx2-positive
isolates the presence of the stx2a and stx2c variants
was investigated.
Results: Twenty-one of 160 cattle (13.1 per cent; 95
per cent CI 8.3 to 19.4 per cent) were found to be
faecal carriers of STEC. STEC O157 was found in 10
(6.3 per cent) samples, STEC O26 in six (3.8 per cent)
and STEC O111 in one (0.6 per cent). Four isolates
(2.5 per cent) were O not determined (OND). Six out of
160 (3.8 per cent; 95 per cent CI 1.4 to 8.0 per cent)
hide samples were positive for STEC; four hides (2.5
per cent) were contaminated by STEC O157 and two
(1.3 per cent) by STEC O26. In three cattle (1.9
per cent) STEC from both faeces and hides were
detected. Among STEC O157, 87.5 per cent of them
carried the stx2c gene and 12.5 per cent carried both
stx1 and stx2c genes. No O157 isolate harboured stx2a
variant. STEC O26 and O111 carried the stx1 gene
only. One OND strain carried both the stx2a and stx2c
genes.
Conclusions: This study shows that STEC O157 from
cattle can harbour the stx2c variant, which is
associated with haemolytic uraemic syndrome in
humans, and that cattle hides may be a source of
human pathogenic STEC O157 and O26 in the
slaughterhouse environment
Antimicrobial resistance, biofilm synthesis and virulence genes in Salmonella isolated from pigs bred on intensive farms
Salmonella is the second cause of foodborne infection in humans in the USA and Europe. Pigs represent the second most important reservoir for the pathogen and the consumption of pork meat is a major risk factor for human salmonellosis. Here, we evaluated the virulence patterns of eleven Salmonella isolated from pigs (carcasses and faces) bred in intensive farms in the north of Italy. The two serotypes identified were S. Typhimurium and its monophasic variant 1,4,5,12:i:-. None of the isolates was an ESBL producer, as confirmed also by PCR. However, the presence of a multidrug resistant pattern was evident, with all the isolates being resistant to at least to five antimicrobial agents belonging to various classes. Moreover, six out of eleven isolates showed important resistance profiles, such as resistance against colistin and ciprofloxacin, with nine to twelve recorded resistances. The isolates were negative for the biofilm synthesis test, while four different virulotypes were characterized. All the isolates showed the presence of invA, hilA, stn, ssrA, sipC. One sample also harbored ssaR and spvC genes. One strain was positive for all the virulence genes tested and was resistant to 12 antimicrobial agents. The present study contributes new data to the surveillance program for antibiotic resistance. Furthermore, the presence of eleven highly virulent isolates poses concern for human health in relation to their diffusion in the environment
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