We present a search for new physics using events with two same-sign isolated leptons with the presence of b-jets in the final state, targetting SUSY scenarios by strong production of squarks and ...gluinos where the 3 super()rdeneration squarks are lighter than other squarks. No excess above the standard model background is observed. The results are interpreted in various SUSY models, and we are able to exclude gluino (sbottom) masses up to 1000 (450) GeV at 95% CL.
The CMS drift tubes (DT) muon detector, built for withstanding the LHC expected integrated and instantaneous luminosities, will be used also in the High Luminosity LHC (HL-LHC) at a 5 times larger ...instantaneous luminosity and, consequently, much higher levels of radiation, reaching about 10 times the LHC integrated luminosity. Initial irradiation tests of a spare DT chamber at the CERN gamma irradiation facility (GIF++), at large (∼O(100)) acceleration factor, showed ageing effects resulting in a degradation of the DT cell performance. However, full CMS simulations have shown almost no impact in the muon reconstruction efficiency over the full barrel acceptance and for the full integrated luminosity. A second spare DT chamber was moved inside the GIF++ bunker in October 2017. The chamber was being irradiated at lower acceleration factors, and only 2 out of the 12 layers of the chamber were switched at working voltage when the radioactive source was active, being the other layers in standby. In this way the other non-aged layers are used as reference and as a precise and unbiased telescope of muon tracks for the efficiency computation of the aged layers of the chamber, when set at working voltage for measurements. An integrated dose equivalent to two times the expected integrated luminosity of the HL-LHC run has been absorbed by this second spare DT chamber and the final impact on the muon reconstruction efficiency is under study. Direct inspection of some extracted aged anode wires presented a melted resistive deposition of materials. Investigation on the outgassing of cell materials and of the gas components used at the GIF++ are underway. Strategies to mitigate the ageing effects are also being developed. From the long irradiation measurements of the second spare DT chamber, the effects of radiation in the performance of the DTs expected during the HL-LHC run will be presented.
In this work a study was carried out on the Al
2O
3/Nb
2O
5/H
3PO
4 system. A-2 alumina from Alcoa (Brazil) was used and the Al
2O
3/Nb
2O
5/H
3PO
4 system with an
Al
2
O
3
P
2
O
5
molar ratio of ...20.3, pressed at 20 and 60 MPa and thermally treated at 110, 300, 500, 800, 1000, 1200, 1400 and 1600 °C, was studied. An attempt was made to relate mechanical properties with porosity as well as with the phases formed during thermically treatment. X-ray diffraction (XRD), infrared spectroscopy (IRS) and magic-angle spinning phosphorus nuclear magnetic resonance (
31P MAS NMR) were used for phase detection. The amorphous AlPO
4 was considered as the low temperature bonding phase. The system studied showed highest mechanical strength at 1400 °C.
The Compact Muon Solenoid (CMS) experiment prepares its Phase-2 upgrade for the high-luminosity era of the LHC operation (HL-LHC). Due to the increase of occupancy, trigger latency and rates, the ...full electronics of the CMS Drift Tube (DT) chambers will need to be replaced. In the new design, the time bin for the digitisation of the chamber signals will be of around 1~ns, and the totality of the signals will be forwarded asynchronously to the service cavern at full resolution. The new backend system will be in charge of building the trigger primitives of each chamber. These trigger primitives contain the information at chamber level about the muon candidates position, direction, and collision time, and are used as input in the L1 CMS trigger. The added functionalities will improve the robustness of the system against ageing. An algorithm based on analytical solutions for reconstructing the DT trigger primitives, called Analytical Method, has been implemented both as a software C++ emulator and in firmware. Its performance has been estimated using the software emulator with simulated and real data samples, and through hardware implementation tests. Measured efficiencies are 96 to 98\% for all qualities and time and spatial resolutions are close to the ultimate performance of the DT chambers. A prototype chain of the HL-LHC electronics using the Analytical Method for trigger primitive generation has been installed during Long Shutdown 2 of the LHC and operated in CMS cosmic data taking campaigns in 2020 and 2021. Results from this validation step, the so-called Slice Test, are presented.
The discovery of the Higgs boson in 2012, by the ATLAS and CMS experiments, was a success achieved with only a percent of the entire dataset foreseen for the LHC. It opened a landscape of ...possibilities in the study of Higgs boson properties, Electroweak Symmetry breaking and the Standard Model in general, as well as new avenues in probing new physics beyond the Standard Model. Six years after the discovery, with a conspicuously larger dataset collected during LHC Run 2 at a 13 TeV centre-of-mass energy, the theory and experimental particle physics communities have started a meticulous exploration of the potential for precision measurements of its properties. This includes studies of Higgs boson production and decays processes, the search for rare decays and production modes, high energy observables, and searches for an extended electroweak symmetry breaking sector. This report summarises the potential reach and opportunities in Higgs physics during the High Luminosity phase of the LHC, with an expected dataset of pp collisions at 14 TeV, corresponding to an integrated luminosity of 3~ab\(^{-1}\). These studies are performed in light of the most recent analyses from LHC collaborations and the latest theoretical developments. The potential of an LHC upgrade, colliding protons at a centre-of-mass energy of 27 TeV and producing a dataset corresponding to an integrated luminosity of 15~ab\(^{-1}\), is also discussed.
The preparation of lithium niobate powder, LiNbO3, using an organic niobium salt and lithium nitrate in a buffer solution of oxalic acid and ammonium oxalate was investigated. Evaporation of this ...starting solution produces a precursor which, upon heat treatment, yields LiNbO3. A chemical formula for this precursor is proposed, based on IR and thermal analysis data. The thermal evolution of the precursor powder, to the point of the formation of the LiNbO3 phase, was followed by means of thermal analysis, IR spectroscopy and powder XRD. The results indicate that total crystallisation occurs after a 550 C heat treatment, showing that single-phase LiNbO3 powder, with a crystallite mean size of 88 nm, can be prepared at low processing temperatures. 28 refs.
The effect of the addition of three types of sludge (L, O and F) on both the Na, K and S volatilisation and the slagging behaviour of a bituminous coal (H) was studied. Na, K and S volatilise in the ...coal, the sludges and their blends partially, and there exist linear relationships between their contents in ashes and the ratio sludge ash/blend ashes for each coal–sludge blend ash series. However, in blends with F (treated with FeCl3 and lime), S relationship is not linear due mainly to the following effects: a) sulphur retention by CaO to form CaSO4, and b) decrease of free CaO due to the formation of ferrites, silicates and phosphates. To determine the slagging tendency, the ash fusion temperatures (AFTs) were related with ash chemical and mineral composition by using the slagging factor, the base/acid ratio, the Fe2O3/CaO ratio, the P2O5 content, and the ternary equilibrium phase diagram SiO2–Al2O3–CaO. Sludge addition to coal produces a decrease in AFTs that depends on the percentage of sludge added, the sludge phosphorus content and additives (FeCl3 and/or lime), the fact that ash composition is near to those of the eutectics, and the formation of Si and P amorphous compounds.
•Na, K and S of coal–sludge blends volatilise partially during ashing process.•In ashes from sludge treated with lime, S is retained as CaSO4 significantly.•Sludge addition to bituminous coal increases P2O5 content and reduces AFTs.•The effect of chemical composition on AFTs was adequately explained by B/A(+P) ratio.•AFT changes are predicted by SiO2–Al2O3–CaO diagram acceptably.
The effect of the addition of three types of sludge (A, V and F) on the slagging behaviour of a brown lignite was investigated. It was evaluated by determining ash fusion temperatures (AFTs) of ...lignite, sludge samples and coal-sludge blends of 10 and 50wt.% of each sludge, together with their chemical and mineral composition. The addition of sludge to lignite produces a decrease in the AFTs, the extent of which depends on the percentage of sludge added to the lignite, as well as the sludge additives used (organic polyelectrolyte, lime and/or FeCl3) and their phosphorus content. As a consequence, the addition of sludge to lignite produces an increase in the slagging tendency. Those lignite–sludge blend ashes whose base to acid ratio (B/A(+P)) ranges from 0.7 to 2.0 have the lowest AFTs. In this range, most of the ash compositions are near to those of SiO2–Al2O3–CaO eutectics. Also, an increase in the phosphorus content of the blends, as well as the formation of amorphous silicates and phosphates, reduce the AFTs.
•Lignite ash fusion temperatures (AFTs) decrease as a consequence of sludge addition.•Sludge addition to lignite increases SiO2, Al2O3, Fe2O3 and P2O5 content in ashes.•B/A(+P) and SiO2–Al2O3–CaO diagram predict adequately AFT changes and slagging.•CaO, Al2O3 and SiO2 form silicates, which can produce low-melting eutectics.•P2O5 from sludge forms phosphates, which reduce AFTs.
Proteases are a set of enzymes that have been involved in multiple biological processes throughout evolution. Among them, extracellular matrix (ECM) remodeling has emerged as one of the most relevant ...functions exerted by these proteins, being essential in the regulation of critical events such as embryonic development or tissue homeostasis. Hence, it is not surprising that dysregulation in any protease function that affects ECM homeostasis may contribute to the aging process. Matrix metalloproteinases (MMPs) are one of the most important families of proteases involved in the tight control of ECM remodeling over time. In this review, we will discuss how MMPs and other proteases alter ECM composition and mechanical properties in aging, thereby affecting stem cell niches and the development of senescent phenotypes. Finally, we will summarize recent findings that associate MMPs with the development of age-related diseases, such as neurodegenerative disorders.
•The ECM undergoes multiple remodeling events mediated by MMPs during aging.•ECM composition and mechanical properties are affected by aging-associated remodeling.•Aged ECM influences stem cell behavior and development of senescent phenotypes.•Age-related decline in MMP activity is associated with the progress of neurological diseases.
The influence of sewage sludge treatment on its pyrolysis and combustion and the N, S and Cl emissions was studied by thermogravimetry-mass spectrometry in the range 25–800 °C. Two types of sludge ...were used (L and F). L underwent anaerobic digestion and was treated with organic polyelectrolyte, while F was treated with FeCl3 and lime. The treatment with inorganic additives had a notable influence on the pyrolysis and combustion processes. During F pyrolysis, the most significant effects of CaO/CaCO3 from lime and Fe2O3 from FeCl3 were: 1) Fe2O3 promoted oxidation reactions, and char gasification at around 600 °C; 2) CaO promoted H2 formation at around 480 °C due to its action on water–shift reaction, and the partial SO2 retention by forming CaSO4. During combustion, Fe2O3 exhibited a high catalytic activity on oxidation reactions. Thus, an intense devolatilisation was produced in the range 200–377 °C, this being accompanied by a high formation of CO2, NO2 and Cl2. Also, the formation of SO2/SO3 was promoted, which were retained by CaCO3/CaO at temperatures higher than 377 °C. The nth-order reaction model describes adequately the global reaction that occurs in each stage, except for the second stage of L combustion that was described by the geometrical contraction model.
•The effect of sewage sludge treatment on its pyrolysis and combustion was studied.•Evolution profiles of CO2, H2O, H2 and N, S, Cl compounds were determined by TG-MS.•Fe2O3 from FeCl3 and CaO modify thermogravimetric and gas profiles and kinetics.•Fe2O3 promotes organic matter oxidation, more oxidized compounds being emitted.•During pyrolysis, CaO and Fe2O3 promote H2 formation and char gasification.
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