A generic expression to compute triple-parton scattering (TPS) cross sections in high-energy proton–nucleus (pA) collisions is derived as a function of the corresponding single-parton cross sections ...and an effective parameter encoding the transverse parton profile of the proton. The TPS cross sections are enhanced by a factor of about
9
A
≃
2000
in pPb as compared to those in proton–nucleon collisions at the same center-of-mass energy. Estimates for triple charm (
c
c
¯
) and bottom (
b
b
¯
) production in pPb collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order calculations for
c
c
¯
and
b
b
¯
single-parton cross sections. At
s
N
N
=
8.8
TeV, about 10% of the pPb events have three
c
c
¯
pairs produced in separate partonic interactions. At
s
N
N
=
63
TeV, the pPb cross sections for triple-
J
/
ψ
and triple-
b
b
¯
are
O
(1–10 mb). In the most energetic collisions of cosmic rays in the upper atmosphere, equivalent to
s
N
N
≈
400 TeV, the TPS
c
c
¯
cross section equals the total p–Air inelastic cross section.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•Hierarchical micro-mesoporous carbons were synthesized.•Highly ordered carbons are prepared by selecting suitable synthesis conditions.•CVD conditions determine the porosity and ...structure of the materials.•Acetylene allows a correct replication of the microporosity.•Propylene allows a better replication of the mesoporosity.
The objective of this work was to produce carbons with controllable bimodal porosity in the micro-mesopore range. Hierarchical micro-mesoporous carbons were prepared by direct replication, using bimodal Y zeolite core/MCM-48 silica shell aluminosilicates as templates. Different variables of the chemical vapor deposition (CVD) process were studied in order to achieve a suitable infiltration of both meso and micropores of the templates. Thus, one-step infiltration with acetylene and also two-step infiltration with acetylene and propylene were performed to further investigate the effect of the precursor and CVD steps duration. One-step acetylene CVD gave the best results since the obtained carbons exhibited high specific surfaces areas of 1000–1323m2/g, and their X-ray diffraction and transmission electron microscopy analysis revealed that they faithfully replicated the hierarchical core–shell structure of the parent template. When propylene was used as carbon source a better replication of the mesoporous shell was achieved, but as a counterpoint, the replication of the microporous core failed.
Proton-nucleus (p+A) collisions have long been recognized as a crucial component of the physics program with nuclear beams at high energies, in particular for their reference role to interpret and ...understand nucleus-nucleus data as well as for their potential to elucidate the partonic structure of matter at low parton fractional momenta (small-x). Here, we summarize the main motivations that make a proton-nucleus run a decisive ingredient for a successful heavy-ion program at the Large Hadron Collider (LHC) and we present unique scientific opportunities arising from these collisions. We also review the status of ongoing discussions about operation plans for the p+A mode at the LHC.
We discuss the physics of large impact parameter interactions at the LHC: ultraperipheral collisions (UPCs). The dominant processes in UPCs are photon–nucleon (nucleus) interactions. The current LHC ...detector configurations can explore hard phenomena at small
x
with nuclei and nucleons at photon–nucleon center-of-mass energies above 1 TeV, extending the
x
range of HERA by a factor of ten. In particular, it will be possible to probe diffractive and inclusive parton densities in nuclei using several processes. The interaction of small dipoles with protons and nuclei can be investigated in elastic and quasi-elastic
J
/
ψ
and
Υ
production as well as in high
t
ρ
0
production accompanied by a rapidity gap. Several of these phenomena provide clean signatures of the onset of the new high gluon density QCD regime. The LHC is in the kinematic range where nonlinear effects are several times larger than those at HERA. Two-photon processes in UPCs are also studied. In addition, while UPCs play a role in limiting the maximum beam luminosity, they can also be used as a luminosity monitor by measuring mutual electromagnetic dissociation of the beam nuclei. We also review similar studies at HERA and RHIC as well as describe the potential use of the LHC detectors for UPC measurements.
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•Hierarchical micro-mesoporous aluminosilicates were synthesized.•Y zeolite core/MCM-48 silica shell structures were obtained.•Y zeolite favors the formation of the ...mesostructure.•Porosity and structure can be varied by modifying the preparation variables.•Duration of the hydrothermal step has a great effect on the materials properties.
A simple procedure to obtain hierarchical micro-mesoporous aluminosilicate composites was developed by growing MCM-48 silica over commercial Y zeolite. The obtained hierarchical composites have a microporous core and a mesoporous shell. The process consists in assembling dispersed Y zeolite with a mesoporous silica phase that is formed “in situ” by “soft-templating” with cetryltrimethylammonium bromide (CTAB) as surfactant. The Y zeolite/MCM-48 silica ratio and aging time were varied to study their effects on the final porosity and structure of the hierarchical composites. The pore textural and structural characteristics of the composites did not match those of the corresponding Y zeolite/MCM-48 silica physical mixtures. This implies that the synthesized composites integrate micropores and mesopores in the same bulk. The obtained composites exhibited micropore and mesopore volumes ranging between 0.15–0.31 and 0.30–0.51cm3/g, respectively. X-ray diffraction and N2 adsorption results revealed that the presence of zeolite in the reaction medium favors the formation of mesopores in the obtained materials, especially for short hydrothermal treatments. TEM results showed that the obtained adsorbents are constituted by an integrated micro-mesoporous bimodal system in which Y zeolite is surrounded by a thin cover of MCM-48 silica.
Hiperparatiroidismo persistente debido a paratiromatosis Fernández M, Raquel; Enterría G, Ángela; Ventosa V, Marta María ...
Revista de otorrinolaringología y cirugía de cabeza y cuello,
12/2018, Letnik:
78, Številka:
4
Journal Article
Hiperparatiroidismo persistente debido a paratiromatosis Fernández M, Raquel; Enterría G, Ángela; Ventosa V, Marta María ...
Revista de otorrinolaringología y cirugía de cabeza y cuello,
12/2018, Letnik:
78, Številka:
4
Journal Article
Odprti dostop
RESUMEN La paratiromatosis se describe como una dolencia en la que existen múltiples nódulos de tejido paratiroideo hiperfuncionante diseminados por cuello y el mediastino, en la cual las pruebas de ...imagen no son efectivas para localizar las glándulas paratiroides y requiere de la combinación de un tratamiento médico y quirúrgico que en ocasiones se presenta como un desafío. Describimos el caso de una mujer de 61 años con hiperparatiroidismo primario recurrente a la que se le extirpan un total de 9 glándulas paratiroideas en 3 cirugías diferentes, y realizamos revisión de la literatura.
Hierarchical micro–mesoporous carbons with high porosity development and ordered structure were prepared. The innovative proposal consists in developing microporosity in ordered mesoporous carbon by ...chemical activation in template presence in order to minimize the structural damage. Thus, we have directly carried out the chemical activation of a mesoporous carbon/silica composite with KOH. The effect on mesoporous ordered structure of both KOH/carbon ratio and activation temperature has been studied. Following chemical activation the specific surface area is increased from 341 to 1757m2/g and the micropore volume becomes almost six times larger than initial value. Although a slight widening of the mesopore distribution and an increase in the mesopore volume has been observed during activation, TEM and XRD results reveal an excellent conservation of the ordered mesoporous structure during activation even at conditions well above the limits that a CMK-3 type carbon can resist.
This document summarises proposed searches for new physics accessible in the heavy-ion mode at the CERN Large Hadron Collider (LHC), both through hadronic and ultraperipheral γγ interactions, and ...that have a competitive or, even, unique discovery potential compared to standard proton-proton collision studies. Illustrative examples include searches for new particles-such as axion-like pseudoscalars, radions, magnetic monopoles, new long-lived particles, dark photons, and sexaquarks as dark matter candidates-as well as new interactions, such as nonlinear or non-commutative QED extensions. We argue that such interesting possibilities constitute a well-justified scientific motivation, complementing standard quark-gluon-plasma physics studies, to continue running with ions at the LHC after the Run-4, i.e. beyond 2030, including light and intermediate-mass ion species, accumulating nucleon-nucleon integrated luminosities in the accessible fb−1 range per month.
A generic expression of double-parton scattering cross sections in high-energy nucleus–nucleus (A–A) collisions is derived as a function of the corresponding single-parton hard cross sections and of ...the A–A event centrality. We consider the case of prompt-J/ψ production in lead–lead (Pb–Pb) at the CERN Large Hadron Collider and find that about 20% (35%) of the J/ψ events in minimum-bias (most central) collisions contain a second J/ψ from double-parton interactions. In Pb–Pb at 5.5 TeV, in the absence of final-state effects, about 240 double-J/ψ events are expected per unit midrapidity and per inverse-nanobarn in the dilepton decay modes. The implications of double-J/ψ production on the interpretation of the observed J/ψ suppression in A–A collisions are discussed.
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