We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5 % most central ...C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158
A
GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent
ϕ
2
=
0
.
96
-
0.25
+
0.38
(stat.)
±
0.16
(syst.)
is consistent with the value expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass
π
+
π
-
pairs in the same Si+Si collisions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nb-containing molecular sieves and Nb
2O
5 (crystalline and amorphous) were used as catalysts in gas phase oxidation of methanol with oxygen, liquid phase oxidation of glycerol with oxygen and ...cyclohexene with hydrogen peroxide. H
2O
2 interacts with the amorphous catalysts towards O
Nb(V)O
2
radicals very active in epoxidation of cyclohexene. It is not the case for Nb in crystalline catalysts, which are active in chemisorption of alcohols.
Display omitted
▶ Difference in oxidation activity if Nb located in amorphous or crystalline catalyst. ▶ H
2O
2 as oxidant – formation of active O
Nb(V)O
2
radicals if amorphous catalyst. ▶ Nb in amorphous oxide – active but not selective in MeOH oxidation. ▶ Nb dispersed in amorphous mesoporous silica active and selective in oxidation. ▶ Nb in supports promotes stabilization of active species loaded (Cu, Au, Sb–V–O
x
).
This paper is devoted to the role of niobium, located in crystalline and amorphous catalysts, in catalytic oxidation reactions. Bulk niobium(V) oxides (crystalline and amorphous), NbMCM-41, NbSBA-3, NbSBA-15 and NbY materials were used as catalysts in gas phase oxidation of methanol with oxygen, liquid phase oxidation of glycerol with oxygen and liquid phase oxidation of cyclohexene with hydrogen peroxide. When H
2O
2 was applied as an oxidation agent the amorphous materials containing niobium species were the most effective catalysts because Nb in such catalysts strongly interacts with H
2O
2 resulting in the formation of active O
Nb(V)O
2
radicals. It was not the case for crystalline catalysts containing niobium. The results obtained for Nb-containing materials used as supports for copper, gold and binary Sb–V–O
x
oxides indicated that niobium species promotes stabilization of the active species loaded. Moreover, it was shown that gold loaded on crystalline niobia increases the catalytic activity in dehydrogenation of methanol and glycerol, which is the first step of their oxidation with oxygen.
Interaction cross sections and charged pion spectra in p+C interactions at 31 GeV/c were measured with the large-acceptance NA61/SHINE spectrometer at the CERN SPS. These data are required to improve ...predictions of the neutrino flux for the T2K long-baseline neutrino oscillation experiment in Japan. A set of data collected during the first NA61/SHINE run in 2007 with an isotropic graphite target with a thickness of 4% of a nuclear interaction length was used for the analysis. The measured p+C inelastic and production cross sections are 257.2 {+-} 1.9 {+-} 8.9 and 229.3 {+-} 1.9 {+-} 9.0 mb, respectively. Inclusive production cross sections for negatively and positively charged pions are presented as functions of laboratory momentum in ten intervals of the laboratory polar angle covering the range from 0 up to 420 mrad. The spectra are compared with predictions of several hadron production models.
Objective: This study aimed to understand COVID-19 pandemic impacts on anxiety, depression, and addictive/excessive behaviors, with exploration of intolerance of uncertainty (IU) and social ...connectedness as potential moderators. Participants: Adult college students participated. Method: Our online survey assessed symptoms and behaviors prior to COVID-19, during the initial outbreak (Wave 1), and during early 2021 (Wave 2). Results: Significant increases were found in anxiety, depression, binge eating, sexual behaviors, video game playing, internet/social media usage, and compulsive exercise in both waves. IU moderated the relationship between both depression/anxiety and certain excessive behaviors; social connectedness moderated the relationship between anxiety and smoking. Conclusions: This study replicated prior work and highlights new impacts on addictive/excessive behaviors, as well as moderating effects from social connectedness and IU. Future research is warranted to evaluate the efficacy of treatments targeting IU and social connectedness as the pandemic continues to unfold.
The interaction of gold particles with a silica surface is investigated using a combination of theoretical and experimental techniques. It is found that the physisorption strength of gold on silica ...decreases with increasing chloride concentration at the surface, with increasing cluster size, and with decreasing oxidation state of gold. However, the gold precursor is adsorbed more strongly than the corresponding precursor fragments and this via an H-bond network. It is also found that chemisorbed, grafted species may coexist on a silica surface, depending on the experimental conditions. From the vibrational frequencies and especially by the presence of a band at 3650 cm−1, it is found that the gold species after calcination are probably present under the form of digrafted chemisorbed species. This information enables us to propose a scenario for the formation of gold clusters at the silica surface.
New data on the production of protons, anti-protons and neutrons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the ...CERN SPS at 158 GeV/c beam momentum. The charged baryons are identified by energy loss measurement in a large TPC tracking system. Neutrons are detected in a forward hadronic calorimeter. Inclusive invariant cross sections are obtained in intervals from 0 to 1.9 GeV/c (0 to 1.5 GeV/c) in transverse momentum and from −0.05 to 0.95 (−0.05 to 0.4) in Feynman
x
for protons (anti-protons), respectively.
p
T
integrated neutron cross sections are given in the interval from 0.1 to 0.9 in Feynman
x
. The data are compared to a wide sample of existing results in the SPS and ISR energy ranges as well as to proton and neutron measurements from HERA and RHIC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The adsorption of HAuCl4, the typical precursor for gold grafting on metal oxide surfaces, is investigated on amorphous silica support. The adsorption of the precursor is investigated as a function ...of its chlorinated form, depending on the pH, using periodic DFT. The results are supported with experimental data based on catalytic probe reactions (acetonylacetone cyclization and oxidation of methanol). The location of chloride ions neighboring hydroxyls gives rise to generation of Brønsted basicity demonstrated by the methylcyclopentenone formation from acetonylacetone and CO2 from methanol. The most stable grafting complex is formed by the AuCl(OH)3 − precursor form on a chloride-free silica surface. The presence of Si−Cl groups at the surface destabilizes the grafting complex.
Niobium and tantalum containing Y zeolites were prepared in a one-pot synthesis and via solid-state ion exchange. The first method led to the incorporation of Nb and Ta into the zeolite framework as ...documented by XRD, UV–vis, XPS and test reactions. The efficiency of the metal introduction was higher for tantalum than for niobium. The presence of Lewis acid sites was proved by pyridine adsorption and cracking of cumene, whereas basic hydroxyls on the surface were evaluated on the basis of 3-methyl-2-cyclopentenone formation in the cyclisation of acetonyl acetone.
Anxiety is one of the most prevalent psychological conditions in the pediatric population, and its associated impairments often persist into adulthood. Pediatricians are in a unique position to ...screen, briefly intervene, and facilitate treatment to prevent long-term impacts. However, they often do not have adequate training to do so. The current study addressed this gap by providing a brief online educational workshop aimed to promote: (1) screening for anxiety and (2) follow-up with appropriate evidence-based interventions. Fifty-three providers participated, and 38 completed surveys pre- and post-training. Findings indicate acceptability of the training to providers, improved knowledge related to anxiety, and increased readiness to manage anxiety during a medical visit. This study supports the utility of a brief, online training on screening and provision of evidence-based treatment for anxiety in pediatric primary care.
Hexagonally ordered mesoporous silicas were applied as supports for chromium species introduced via incipient wetness impregnation. Formation of active centres as a result of the post-synthesis ...modification with CrO
3 was found to depend strongly on the preparation conditions used in the synthesis of the support.
Hexagonally ordered mesoporous silicas of MCM-41 type, SBA-3 and SBA-15 were applied as supports for chromium species introduced via incipient wetness impregnation. The samples were characterised by XRD, N
2 adsorption, UV–vis spectroscopy, H
2-TPR, and a test reaction (acetonylacetone cyclisation). Their catalytic performance in sulphurisation of methanol was studied. Formation of active centres on mesoporous silica supports as a result of the post-synthesis modification with CrO
3 was found to depend strongly on the preparation conditions used in the synthesis of the support. These conditions determined not only the textural/structural parameters but also surface properties of the support, important for the anchoring of metal species which is crucial for catalytic activity.
PDF
