933 research outputs found
The Cosmic Ray p+He energy spectrum in the 3-3000 TeV energy range measured by ARGO-YBJ
The ARGO-YBJ experiment is a full coverage air shower detector operated at
the Yangbajing International Cosmic Ray Observatory. The detector has been in
stable data taking in its full configuration since November 2007 to February
2013. The high altitude and the high segmentation and spacetime resolution
offer the possibility to explore the cosmic ray energy spectrum in a very wide
range, from a few TeV up to the PeV region. The high segmentation allows a
detailed measurement of the lateral distribution, which can be used in order to
discriminate showers produced by light and heavy elements. In this work we
present the measurement of the cosmic ray light component spectrum in the
energy range 3-3000 TeV. The analysis has been carried out by using a
two-dimensional unfolding method based on the Bayes' theorem.Comment: Talk given at RICAP14 conferenc
Cosmic ray light component (p+He) energy spectrum measured by the ARGO–YBJ experiment in the 3–3000 TeV energy range
The energy spectrum and composition of Cosmic Rays (CR) play an important role in the understanding of the acceleration and propagation mechanisms of high-energy particles. The ARGO–YBJ experiment (Yanbajing, Tibet, P. R.
China, 4300 m a.s.l.) is a ground-based air shower detector designed in order to detect showers produced by primaries in the 1–104 TeV energy range. The high spacetime resolution of the detector allows a precise measurement of the lateral particle distribution. This information can be exploited in order to discriminate showers produced by primaries of different mass. In this work the measurement
of the Proton plus Helium energy spectrum is presented in the 1–3000TeV energy range. A deviation from a single power law is clearly evident at energies less than 1PeV
Atmospheric neutrino spectrum reconstruction with JUNO
The atmospheric neutrino flux represents a continuous source that can be
exploited to infer properties about Cosmic Rays and neutrino oscillation
physics. The JUNO observatory, a 20 kt liquid scintillator currently under
construction in China, will be able to detect atmospheric neutrinos , given the
large fiducial volume and the excellent energy resolution. The light produced
in neutrino interactions will be collected by a double-system of photosensors:
about 18.000 20" PMTs and about 25.000 3" PMTs. The rock overburden above the
experimental hall is around 700 m and the experiment is expected to complete
construction in 2021. In this study, the JUNO performances in reconstructing
the atmospheric neutrino spectrum have been evaluated. The different time
evolution of scintillation light on the PMTs allows to discriminate the flavor
of the primary neutrinos. To reconstruct the time pattern of events, the
signals from 3" PMTs only have been used, because of the small time resolution.
A probabilistic unfolding method has been used, in order to infer the primary
neutrino energy spectrum by looking at the detector output. The simulated
spectrum has been reconstructed between 100 MeV and 10 GeV, showing a great
potential of the detector in the atmospheric low energy region. The
uncertainties on the final flux, including both statistic and the systematic
contributions, range between 10% and 25%, with the best performances obtained
at the GeV.Comment: 7 pages, 7 figures. Proceeding for a parallel talk at the 2019
EPS-HEP Conference. arXiv admin note: text overlap with arXiv:1901.1034
Calix[4]arene-based molecular photosensitizers for sustainable hydrogen production and other solar applications
This review collects the most representative literature reports on the use of calix[4]arene-based molecules as components, namely photosensitizer dyes, in solar devices, including photovoltaics (dye-sensitized solar cells, DSSC), hydrogen photocatalytic and photoelectrochemical generation from water and sunlight, and CO2 photoreduction. Calix[4]arenes are versatile and easily obtainable scaffolds to be integrated with solar device molecular components either as electron donor groups in pi-conjugated dyes or as host-guest moieties to favor intermolecular interactions. Their beneficial role has been exploited to enhance photovoltaic, hydrogen production, and CO2 reduction performance, paving the way to a new class of molecular active components for next generation solar devices
The contradictory effect of the methoxy-substituent in palladium-catalyzed ethylene/methyl acrylate cooligomerization
Two new nonsymmetric bis(aryl-imino)acenaphthene ligands (Ar,Ar'-BIAN) and one symmetric Ar2-BIAN were studied. The three ligands share the presence of at least one methoxy group on one of the two aryl rings. These ligands were used for the synthesis of neutral and monocationic palladium(II) complexes of general formula [Pd(CH3)Cl(N-N)] and [Pd(CH3)(L)(N-N)][PF6] (N-N = Ar,Ar'-BIAN, Ar2-BIAN; L = CH3CN, dmso). Due to the nonsymmetric nature of the ligands and their coordination to palladium in a nonsymmetric chemical environment, cis and trans isomers are possible for the three series of complexes with Ar,Ar'-BIANs. Both a detailed NMR investigation in solution and the X-ray characterization in solid state point out that the trans isomer is the preferred species for the neutral derivatives, whereas for the cationic compounds a decrease in the stereoselectivity of the coordination is observed. One of the new Ar,Ar'-BIANs differs from an already reported nonsymmetric \uf061-diimine for the replacement, on one aryl ring, of a methyl group with a methoxy susbtituent, thus allowing a comparison of the structural features of the relevant complexes. The monocationic complexes were tested as precatalysts for the ethylene/methyl acrylate copolymerization under mild reaction conditions. Despite the structural similarities observed in solution with the already known precatalysts, the present compounds demonstrated a remarkable decrease in the productivity values associated to a higher affinity for the polar monomer
Henoch-Schönlein Purpura in children: Not only kidney but also lung
Background: Henoch-Sch\uf6nlein Purpura (HSP) is the most common vasculitis of childhood and affects the small blood vessels. Pulmonary involvement is a rare complication of HSP and diffuse alveolar hemorrhage (DAH) is the most frequent clinical presentation. Little is known about the real incidence of lung involvement during HSP in the pediatric age and about its diagnosis, management and outcome. Methods: In order to discuss the main clinical findings and the diagnosis and management of lung involvement in children with HSP, we performed a review of the literature of the last 40 years. Results: We identified 23 pediatric cases of HSP with lung involvement. DAH was the most frequent clinical presentation of the disease. Although it can be identified by chest x-ray (CXR), bronchoalveolar lavage (BAL) is the gold standard for diagnosis. Pulse methylprednisolone is the first-line of therapy in children with DAH. An immunosuppressive regimen consisting of cyclophosphamide or azathioprine plus corticosteroids is required when respiratory failure occurs. Four of the twenty-three patients died, while 18 children had a resolution of the pulmonary involvement. Conclusions: DAH is a life-threatening complication of HSP. Prompt diagnosis and adequate treatment are essential in order to achieve the best outcome
From: Trash to resource: Recovered-Pd from spent three-way catalysts as a precursor of an effective photo-catalyst for H2 production
The successful production of a nanostructured and highly dispersed Pd-TiO2 photo-catalyst, using [Pd(Me2dazdt)2](I3)2 (Me2dazdt = N,N\u2032-dimethyl-perhydrodiazepine-2,3-dithione) salt, obtained through the selective and safe recovery of palladium from model exhaust three-way catalysts (TWCs), is reported here. The photo-catalyst prepared by the impregnation/photo-reduction of palladium on the support showed improved performance in H2 production from methanol and in glycerol photo-reforming compared to reference photo-catalysts obtained from conventional Pd-salts. The reported results represent a case of successful palladium \u201crecovery and re-employment\u201d and thus constitute an example of green chemistry by providing, in one route, the environmentally friendly recovery of a critical metal and its employment in the renewable energy field
Unraveling the effect of proliferative stress in vivo in hematopoietic stem cell gene therapy mouse study
The hematopoietic system of patients enrolled in hematopoietic stem cells (HSC) gene therapy (GT) treatments is fully reconstituted upon autologous transplantation of engineered stem cells. HSCs highly proliferate up to full restoration of homeostasis and compete for niche homing and engraftment. The impact of the proliferation stress in HSC on genetic instability remains an open question that cured patients advocate for characterizing long-term safety and efficacy. The accumulation of somatic mutations has been widely used as a sensor of proliferative stress. Vector integration site (IS) can be used as a molecular tool for clonal identity, inherited by all HSC progeny, to uncover lineage dynamics in vivo at single-cell level. Here we characterized at single-clone granularity the proliferative stress of HSCs and their progeny over time by measuring the accumulation of mutations from the DNA of each IS. To test the feasibility of the approach, we set-up an experimental framework that combines tumor-prone Cdkn2a-/- and wild type (WT) mouse models of HSC-GT and molecular analyses on different hematopoietic cell lineages after transplantation of HSCs transduced with genotoxic LV (LV.SF.LTR) or GT-like non-genotoxic LV (SIN.LV.PGK). The Cdkn2a-/- mouse model provided the experimental conditions to detect the accumulation of somatic mutations, since the absence of p16INK4A and p19ARF enhances the proliferative potential of cells that have acquired oncogenic mutations. As expected, mice transplanted with Cdkn2a-/- Lin- cells marked with LV.SF.LTR (N=24) developed tumors significantly earlier compared to mock (N=20, p<0.0001), while mice treated with SIN. LV.PGK (N=23) did not. On the other side, mice that received WT
Lin- cells treated with LV.SF.LTR (N=25) or SIN.LV.PGK (N=24) vector have not developed tumors. Given this scenario, we expect that Cdkn2a-/- Lin- cells transduced with LV.SF.LTR are associated with higher mutation rates compared to the SIN.LV.PGK group and wild type control mice. The composition of peripheral blood, lymphoid (B and T) and myeloid compartments was assessed by FACS on samples collected every 4 weeks and IS identification. More than 200,000 IS have been recovered. To identify the presence of somatic mutations, the genomic portions of sequencing reads flanking each different IS were analyzed with VarScan2. The accumulation rates of mutations have been evaluated by our new Mutation Index (MI) which normalizes the number of mutations by clones and coverage. Considering that a large portion of IS has been discarded since not covered by a minimum number of 5 unique reads (genomes), the remaining number of IS contained >90% of reads in each group. The MI increased over time in both LV.SF.LTR groups, with higher values for the Cdkn2a-/-. On the other hand, treatment with SIN.LV.PGK resulted in lower MI in both groups compared to LV.SF.LTR groups, reflecting the higher clonal composition of the cells treated with the SIN.LV.PGK and the phenomenon of insertional mutagenesis in the LV.SF.LTR. Moreover, the higher MI values of the SIN.LV.PGK Cdkn2a-/- group compared with the WT group proved the induction of DNA fragility. Our results showed that the analysis of the accumulation of somatic mutations at single clone unraveled HSC proliferation stress in vivo, combining for the first time the analysis of acquired mutations with IS. We are now applying our model to different clinical trials, and studying HSCs sub- clonal trees by symmetric divisions, previously indistinguishable by IS only. Our study will open the doors to in vivo long-term non-invasive studies of HSC stability in patients
Acquisition of somatic mutations after hematopoietic stem cell gene therapy varies among cell lineages and is modulated by vector genotoxicity and the activity of key cellular senescence gene
The hematopoietic system of patients undergoing Hematopoietic Stem and Progenitor Cell (HSPC) Gene Therapy (GT) is fully restored when autologous engineered HSPCs are reinfused into the patient. During this process, HSPCs go through a high level of proliferation until the hematopoietic reconstitution is complete. The impact of proliferation in HSPCs on cellular fitness and safety remains an open question. Moreover, the accumulation of somatic mutations in vivo could show differences in different hematopoietic lineages depending on their susceptibility to the negative effects elicited by the DNA damage response. Furthermore, oncogene activation in human HSPCs has been shown to trigger a chronic inflammatory response leading to hematopoietic decay. Here we studied the clonality and the accumulation of somatic mutations in different hematopoietic lineages and during hematopoietic reconstitution in mice subjected to HSPC-GT. Indeed, wild type C57 mice were transplanted with bone marrow-derived lineage negative (Lin-) cells from WT mice or tumor-prone Cdkn2a-/- mice which lack p16INK4A and p19ARF proteins and thus have no barriers against proto-oncogene activation. Moreover, to evaluate if genotoxic integrations may increase the probability of acquiring somatic mutation upon oncogene activation, Lin- cells were transduced with a genotoxic LV harboring the strong retroviral enhancer/promoter Spleen Focus Forming Virus in the LTR (LV.SF.LTR) or the safer GTlike non-genotoxic LV (SIN.LV.PGK). Mice receiving WT Lin- cells treatedwith LV.SF.LTR (N= 25) or SIN.LV.PGK (N= 24) did not develop tumors, while mice transplanted with Cdkn2a/LV.SF.LTR-marked cells (N = 24) developed tumors significantly earlier compared to mock (N = 20, p < 0.0001) and mice receiving Cdkn2a/SIN.LV.PGK-treated cells (N = 23, p < 0.0001). To evaluate the clonal dynamics of hematopoietic reconstitution, vector integration sites (IS)were identified by by Sonication Mediated Integration Site (SLiM) PCR from peripheral blood, lymphoid (B and T) and myeloid cells collected every 4 weeks post transplantation. Somatic mutations were identified by analyzing the mouse genomic portion flanking each IS using VarScan2. Overall, we detected >200,000 IS, corresponding to more than 135 Mb of genomic sequence information. We introduced a new Mutation Index (MI), which normalizes the number of mutations by clones and coverage to assess mutation accumulation rates. By this approach, we found that the MI increased over time in LV.SF.LTR-treated mice and was significantly higher when compared to SIN.LV.PGK-treated mice (p < 0.001). Notably, myeloid clones exhibited a higher frequency of mutation accumulation compared to T and B cell lineages. This phenomenon was further exacerbated in Cdkn2a/LV.SF.LTR-marked cells, indicating that the absence of barriers to proto-oncogene activation and the presence of genotoxic insertions result in progressive somatic mutation accumulation and insertional mutagenesis. These results demonstrate for the first time that by combining the assessment of acquired mutations with IS analysis at the single clone level we can identify differential accumulations of somatic mutations in different hematopoietic lineages in vivo which depend on the genotoxic potential of the vector used and the ability of the genetically modified cells to sense and react to genotoxic lesions
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