Results on top-quark physics from the CMS experiment

The most recent results on top-quark physics reported by the CMS experiment at the Large Hadron Collider (LHC) are presented in this talk. The results are based on a data sample of about 36/pb of data collected during 2010 at a pp center-of-mass energy of 7 TeV.Comment: 8 pages, 3 figures Contributed to the Ninth International Conference on Flavor Physics and CP Violation (FPCP 2011), Maale Hachamisha, Israel, May 23--27, 201

Bottomonium Results By BaBar

Summary: Observation of {eta}{sub b}; Energy scan above {Upsilon}(4S); Search for {Upsilon} {r_arrow} {gamma}A{sup 0}, A{sup 0} {r_arrow} invisible; Hadronic transitions {Upsilon}(4S) {r_arrow} {Upsilon}(nS)

Probing the Atomic Arrangement of Sub-Surface Dopants in a Silicon Quantum Device Platform

High-density structures of sub-surface phosphorus dopants in silicon continue to garner interest as a silicon-based quantum computer platform, however, a much-needed confirmation of their dopant arrangement has been lacking. In this work, we take advantage of the chemical specificity of X-ray photoelectron diffraction to obtain the precise structural configuration of P dopants in sub-surface Si:P $\delta$-layers. The growth of $\delta$-layer systems with different levels of doping is carefully studied and verified using X-ray photoelectron spectroscopy and low-energy electron diffraction. Subsequent XPD measurements reveal that in all cases, the dopants primarily substitute with Si atoms from the host material. Furthermore, no signs of free carrier-inhibiting P$-$P dimerization can be observed. Our observations not only settle a nearly decade-long debate about the dopant arrangement but also demonstrate that XPD is well suited to study sub-surface dopant structures. This work thus provides valuable input for an updated understanding of the behavior of Si:P $\delta$-layers and the modeling of their derived quantum devices

The highest oxidation state observed in graphene-supported sub-nanometer iron oxide clusters

Iron oxide nanoclusters are of interest for a broad range of applications, but limited experimental information on their oxidation mechanism is available outside of the gas phase. Here, the oxidation of graphene-supported size-selected Fe-n clusters is studied using high-resolution X-ray Photoelectron Spectroscopy.Size-selected iron oxide nanoclusters are outstanding candidates for technological-oriented applications due to their high efficiency-to-cost ratio. However, despite many theoretical studies, experimental works on their oxidation mechanism are still limited to gas-phase clusters. Herein we investigate the oxidation of graphene-supported size-selected Fe-n clusters by means of high-resolution X-ray Photoelectron Spectroscopy. We show a dependency of the core electron Fe 2p(3/2) binding energy of metallic and oxidized clusters on the cluster size. Binding energies are also linked to chemical reactivity through the asymmetry parameter which is related to electron density of states at the Fermi energy. Upon oxidation, iron atoms in clusters reach the oxidation state Fe(II) and the absence of other oxidation states indicates a Fe-to-O ratio close to 1:1, in agreement with previous theoretical calculations and gas-phase experiments. Such knowledge can provide a basis for a better understanding of the behavior of iron oxide nanoclusters as supported catalysts

Mixed Cation Halide Perovskite under Environmental and Physical Stress

Despite the ideal performance demonstrated by mixed perovskite materials when used as active layers in photovoltaic devices, the factor which still hampers their use in real life remains the poor stability of their physico-chemical and functional properties when submitted to prolonged permanence in atmosphere, exposure to light and/or to moderately high temperature. We used high resolution photoelectron spectroscopy to compare the chemical state of triple cation, double halide Cs [Formula: see text] (FA [Formula: see text] MA [Formula: see text]) [Formula: see text] Pb(I [Formula: see text] Br [Formula: see text]) [Formula: see text] perovskite thin films being freshly deposited or kept for one month in the dark or in the light in environmental conditions. Important deviations from the nominal composition were found in the samples aged in the dark, which, however, did not show evident signs of oxidation and basically preserved their own electronic structures. Ageing in the light determined a dramatic material deterioration with heavily perturbed chemical composition also due to reactions of the perovskite components with surface contaminants, promoted by the exposure to visible radiation. We also investigated the implications that 2D MXene flakes, recently identified as effective perovskite additive to improve solar cell efficiency, might have on the labile resilience of the material to external agents. Our results exclude any deleterious MXene influence on the perovskite stability and, actually, might evidence a mild stabilizing effect for the fresh samples, which, if doped, exhibited a lower deviation from the expected stoichiometry with respect to the undoped sample. The evolution of the undoped perovskites under thermal stress was studied by heating the samples in UHV while monitoring in real time, simultaneously, the behaviour of four representative material elements. Moreover, we could reveal the occurrence of fast changes induced in the fresh material by the photon beam as well as the enhanced decomposition triggered by the concurrent X-ray irradiation and thermal heating

The Molecular and Cellular Basis of Tumor Rejection After Vaccination With Mammary Adenocarcinoma Cells Transduced With the MHC Class II Transactivator CIITA

CD8+ T cell responses are major players of tumor eradication in various vaccination protocols. However, an optimal stimulation of CD4+ T helper cells is required for both priming and maintenance of the effector CTL response against the tumor. In this study we show that the murine mammary adenocarcinoma cell line TS/A, a highly malignant MHC-II-negative tumor, is rejected in vivo if genetically engineered to express MHC-II molecules by transfer of the MHC-II transactivator CIITA. TS/ACIITA cells are fully rejected by 93% of the syngeneic recipients and have a significantly lower growth rate in the remaining 7% of animals. Rejection requires CD4+ and CD8+ cells. CD4+ T cells are fundamental in the priming phase, whereas CTLs are the major anti-tumor effectors. All tumor rejecting animals are protected against rechallenge with the parental TS/A tumor. Immunohistochemical data at day 5 post-inoculation showed an higher infiltrate of CD4+ T cells in mice bearing TS/A-CIITA, than in mice bearing the TS/A tumor. Subsequently, from day 7 trough day 10, TS/A-CIITA tumors showed higher number of both CD4+ and CD8+ cells, dendritic cells, together with massive necrosis. The frequency of IFN-αsecreting splenocytes early after inoculations was also assessed by an ex vivo ELISPOT assay. Only the rejecting TS/A-CIITA animals showed an high frequency of IFN-αsecreting cells (between 80 and 120/106 splenocytes). Importantly, CD4 and CD8 depletion experiments revealed that at the time of tumor resolution the major cell population recognizing the TS/A-CIITA cells was of CD4 origin. This is the first example of successful tumor vaccination by genetic transfer of CIITA. These results open the way to a possible use of CIITA for increasing both the inducing and the effector phase of the anti-tumor response. from 2005 International Meeting of The Institute of Human Virology Baltimore, USA, 29 August – 2 September 200

Atomic Undercoordination in Ag Islands on Ru(0001) Grown via Size-Selected Cluster Deposition: An Experimental and Theoretical High-Resolution Core-Level Photoemission Study

The possibility of depositing precisely mass-selected Ag clusters (Ag-1, Ag-3, and Ag-7) on Ru(0001) was instrumental in determining the importance of the in-plane coordination number (CN) and allowed us to establish a linear dependence of the Ag 3d(5/2) core-level shift on CN. The fast cluster surface diffusion at room temperature, caused by the low interaction between silver and ruthenium, leads to the formation of islands with a low degree of ordering, as evidenced by the high density of low-coordinated atomic configurations, in particular CN = 4 and 5. On the contrary, islands formed upon Ag-7 deposition show a higher density of atoms with CN = 6, thus indicating the formation of islands with a close-packed atomic arrangement. This combined experimental and theoretical approach, when applied to clusters of different elements, offers the perspective to reveal nonequivalent local configurations in two-dimensional (2D) materials grown using different building blocks, with potential implications in understanding electronic and reactivity properties at the atomic level

Effect of chestnut tannins and short chain fatty acids as anti-microbials and as feeding supplements in broilers rearing and meat quality

Chestnut tannins (CT) and saturated short medium chain fatty acids (SMCFA) are valid alternatives to contrast the growth of pathogens in poultry rearing, representing a valid alternative to antibiotics. However, the effect of their blends has never been tested. Two blends of CT extract and Sn1-monoglycerides of SMCFA (SN1) were tested in vitro against the proliferation of Clostridium perfringens, Salmonella typhymurium, Escherichia coli, Campylobacter jejuni. The tested concentrations were: 3.0 g/kg of CT; 3.0 g/kg of SN1; 2.0 g/kg of CT and 1.0 g/kg of SN1; 1.0 g/kg of CT and 2.0 g/kg of SN1. Furthermore, their effect on broiler performances and meat quality was evaluated in vivo: one-hundred Ross 308 male birds were fed a basal diet with no supplement (control group) or supplemented with CT or SN1 or their blends at the same concentration used in the in vitro trial. The in vitro assay confirmed the effectiveness of the CT and SN1 mixtures in reducing the growth of the tested bacteria while the in vivo trial showed that broiler performances, animal welfare and meat quality were not negatively affected by the blends, which could be a promising alternative in replacing antibiotics in poultry production

In situ observation of the on-surface thermal dehydrogenation of n-octane on Pt(111)

The catalytic dehydrogenation of alkanes constitutes a key step for the industrial conversion of these inert sp3-bonded carbon chains into other valuable unsaturated chemicals. To this end, platinum-based materials are among the most widely used catalysts. In this work, we characterize the thermal dehydrogenation of n-octane (n-C8H18) on Pt(111) under ultra-high vacuum using synchrotron-radiation X-ray photoelectron spectroscopy, temperature-programmed desorption and scanning tunneling microscopy, combined with ab initio calculations. At low activation temperatures, two different dehydrogenation stages are observed. At 330 K, n-C8H18 effectively undergoes a 100% regioselective single C-H bond cleavage at one methyl end. At 600 K, the chemisorbed molecules undergo a double dehydrogenation, yielding double bonds in their carbon skeletons. Diffusion of the dehydrogenated species leads to the formation of carbon molecular clusters, which represents the first step towards poisoning of the catalyst. Our results reveal the chemical mechanisms behind the first stages of alkane dehydrogenation on a platinum model surface at the atomic scale, paving the way for designing more efficient dehydrogenation catalystsThe authors acknowledge financial support from projects PID2021-12509OA-I00, PID2020-113142RB-C21, TED2021-129999B-C31, TED2021-129416A-I00, RYC2020-029800-I and EUR2021-122006 funded by MCIN/AEI/10.13039/501100011033. D. Arribas acknowledges the Spanish Ministry of Universities, FPU-2019 predoctoral grant (FPU19/04556