This paper investigates the effect of curing time and aggressive environmental exposure on the mechanical performance of impregnated Carbon Fabric Reinforced Cementitious Matrix (CFRCM) composite. ...Following the recently published IIC-ES AC434 guidelines, saltwater, distilled water, alkali and acid resistance are investigated together with freeze-thaw cycles. Mechanical characterization is based on tensile uni-axial tests under deformation control of rectangular-base prismatic specimens. 28- and 60-day curing times are considered for the control environment as well as for saltwater and alkali resistance. Deformation is monitored via digital acquisition. Besides uni-axial tests, experimental results comprise optical and scanning electron microscopy, crack pattern analysis and failure mechanism assessment. Focus is set on the determination of the design limits for the composite system at failure for the tested environments and curing times. In particular, a comparison is drawn with established design criteria already coded for FRP systems, which introduce the concept of safety (or partial) factors. Environmental conversion factors are also defined and calculated on a statistical basis in a twofold manner, as a mean to determine the design strain and strength limits of exposed specimens from the control (unexposed) data. It is found that they provide a convenient method for assessing the composite vulnerability to the aggressive environments at different curing times.
Motivated by the unexpected appearance of shear horizontal Rayleigh surface waves, we investigate the mechanics of antiplane wave reflection and propagation in couple stress (CS) elastic materials. ...Surface waves arise by mode conversion at a free surface, whereby bulk travelling waves trigger inhomogeneous modes. Indeed, Rayleigh waves are perturbations of the travelling mode and stem from its reflection at grazing incidence. As is well known, they correspond to the real zeros of the Rayleigh function. Interestingly, we show that the same generating mechanism sustains a new inhomogeneous wave, corresponding to a purely imaginary zero of the Rayleigh function. This wave emerges from 'reflection' of a bulk standing mode: This produces a new type of Rayleigh-like wave that travels
, as opposed to along, the free surface, with a speed lower than that of bulk shear waves. Besides, a third complex zero of the Rayleigh function may exist, which represents waves attenuating/exploding both along and away from the surface. Since none of these zeros correspond to leaky waves, a new classification of the Rayleigh zeros is proposed. Furthermore, we extend to CS elasticity Mindlin's boundary conditions, by which partial waves are identified, whose interference lends Rayleigh-Lamb guided waves. Finally, asymptotic analysis in the thin-plate limit provides equivalent one-dimensional models.
IntroductionPatients with schizophrenia tend to have high rates of suicidal ideation (SI), which consists of thoughts of self-destruction, which increase the risk of self-extermination.ObjectivesTo ...determine the prevalence of SI and investigate associated factors in a sample of patients with schizophrenia.MethodsDescriptive and cross-sectional study, in which 49 patients with the condition were selected by convenience, treated at the Psychosis Outpatient Clinic of the Base Hospital of São José do Rio Preto/SP, between August/2021 and March/2022. The following were applied: 1) Sociodemographic Questionnaire, 2) Suicide Ideation Section of the Columbia Suicide Risk Assessment Scale (SISC-SSRS), 3) Suicide Risk Questionnaire from the Mini International Neuropsychiatric Interview (SRQ-MINI). Data were analyzed quantitatively (descriptive statistics and non-parametric tests; p<0.05). The study was approved by the local Research Ethics Committee.ResultsThe age of the participants ranged from 17 to 72 years (mean=45.8 ±14.02), most were male (n=34;69.4%), had not completed elementary school (n=25; 51%), did not have a paid job (n=41; 83.7%) and had a family income of up to three minimum wages (n=23;46.9%). 40.8% (n=20) reported at least one suicide attempt. According to the SISC-SSRS, in the last month: 22.9% (n=11) wished they were dead; 18.8% (n=9) thought about killing themselves; 12.5% (n=6) considered how they could perform the act; 10.4% (n=5) had intention and active planning; and 10.4 (n=5) persisted for the purpose of execution. The mean of affirmative answers was equal to 0.75 (±1.55). In turn, in the SRQ-MINI, 79.6% (n=39) had a score indicating low risk for suicide, 18.4% (n=9) high risk and 2% (n=1) moderate risk. The overall mean was 5.77 (±10.31), which indicates a moderate risk for suicide. There was a non-significant negative correlation between the risk of suicide and the factors of education (r= -0.20; p=0.15) and family income (r= -0.21; p=0.13). There was a significant positive correlation (r=0.81; p=0.0001) between the SISC-SSRS and SRQ-MINI, which indicates that despite the adapted use of the instrument, there is consistency and reliability in the results.ConclusionsThe sample showed low rates of active SI and variation between low and moderate risk for suicide. SI should be asked to patients with schizophrenia, with a view to preventing suicidal behavior.Disclosure of InterestNone Declared
Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by different phenotypes with either bronchial airways alterations or emphysema prevailing. As blood biomarkers ...could be clinically useful for COPD stratification, we aimed at investigating the levels of blood biomarkers in COPD patients differentiated by phenotype: prevalent chronic airway disease versus emphysema.
In 23 COPD patients with prevalent airway disease (COPD-B), 22 COPD patients with prevalent emphysema (COPD-E), 9 control smokers (CSs), and 18 control nonsmokers (CNSs), we analyzed the expression levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, epidermal growth factor (EGF), monocyte chemotactic protein (MCP)-1, and vascular endothelial growth factor by enzyme-linked immunosorbent assay in plasma/serum; glutathione peroxidase and superoxide dismutase (SOD)-1 by immunochemical kits in plasma; and free F2-isoprostanes (F2-IsoPs) by gas chromatography in plasma.
F2-IsoPs level was increased in COPD-B and COPD-E compared with CSs and CNSs; in addition, CS showed higher levels than CNSs; SOD1 level was lower in COPD-B and COPD-E than that in CNSs. Interestingly, MCP-1 level was higher only in COPD-E versus CSs and CNSs; EGF and IL-8 levels were higher in COPD-B and COPD-E versus CNSs; IL-6 level was increased in all three smoking groups (COPD-B, COPD-E, and CSs) versus CNS; IFN-γ and IL-1α levels were higher in CSs than in CNSs; and IL-1α level was also higher in CSs versus COPD-B and COPD-E. In all subjects, F2-IsoPs level correlated positively and significantly with MCP-1, IL-2, IL-1β, IFN-γ, and TNF-α and negatively with SOD1. When correlations were restricted to COPD-E and COPD-B groups, F2-IsoPs maintained the positive associations with IFN-γ, TNF-α, and IL-2.
We did not find any specific blood biomarkers that could differentiate COPD patients with prevalent airway disease from those with prevalent emphysema. The MCP-1 increase in COPD-E, associated with the imbalance of oxidant/antioxidant markers, may play a role in inducing emphysema.
The experimental set-up of the RIB in-flight facility EXOTIC Pierroutsakou, D.; Boiano, A.; Boiano, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2016, Letnik:
834
Journal Article
Recenzirano
Odprti dostop
We describe the experimental set-up of the Radioactive Ion Beam (RIB) in-flight facility EXOTIC consisting of: (a) two position-sensitive Parallel Plate Avalanche Counters (PPACs), dedicated to the ...event-by-event tracking of the produced RIBs and to time of flight measurements and (b) the new high-granularity compact telescope array EXPADES (EXotic PArticle DEtection System), designed for nuclear physics and nuclear astrophysics experiments employing low-energy light RIBs. EXPADES consists of eight ΔE–Eres telescopes arranged in a cylindrical configuration around the target. Each telescope is made up of two Double Sided Silicon Strip Detectors (DSSSDs) with a thickness of 40/60μm and 300μm for the ΔE and Eres layer, respectively. Additionally, eight ionization chambers were constructed to be used as an alternative ΔE stage or, in conjunction with the entire DSSSD array, to build up more complex triple telescopes. New low-noise multi-channel charge-sensitive preamplifiers and spectroscopy amplifiers, associated with constant fraction discriminators, peak-and-hold and Time to Amplitude Converter circuits were developed for the electronic readout of the ΔE stage. Application Specific Integrated Circuit-based electronics was employed for the treatment of the Eres signals. An 8-channel, 12-bit multi-sampling 50MHz Analog to Digital Converter, a Trigger Supervisor Board for handling the trigger signals of the whole experimental set-up and an ad hoc data acquisition system were also developed. The performance of the PPACs, EXPADES and of the associated electronics was obtained offline with standard α calibration sources and in-beam by measuring the scattering process for the systems 17O+58Ni and 17O+208Pb at incident energies around their respective Coulomb barriers and, successively, during the first experimental runs with the RIBs of the EXOTIC facility.
The mechanism of reactions with weakly-bound proton-rich nuclei at energies near the Coulomb barrier is a long-standing open question owing to the paucity of experimental data. In this study, a ...complete kinematics measurement was performed for the proton drip-line nucleus 17F interacting with 58Ni at four energies near the Coulomb barrier. Thanks to the powerful performance of the detector array, exhaustive information on the reaction channels, such as the differential cross sections for quasielastic scattering, exclusive and inclusive breakup, as well as for fusion-evaporation protons and alphas, was derived for the first time. The angular distributions of quasielastic scattering and exclusive breakup can be described reasonably well by the continuum-discretized coupled-channels calculations. The inclusive breakup was investigated using the three-body model proposed by Ichimura, Austern, and Vincent, and results indicate the non-elastic breakup is the dominant component. The total fusion cross sections were determined by the fusion-evaporation protons and alphas. Based on the measured exclusive breakup data, the analysis of the classical dynamical simulation code PLATYPUS demonstrates that the incomplete fusion plays a minor role. Moreover, compared with 16O+58Ni, both the reaction and total fusion cross sections of 17F+58Ni exhibit an enhancement in the sub-barrier energy region, which mainly arises from couplings to the continuum states. This work indicates that the information of full reaction channels is crucially important to comprehensively understand the reaction mechanisms of weakly bound nuclear systems.
The experimental results recently obtained for fusion reactions at energies close to the Coulomb barrier with light radioactive (loosely bound) beams are reviewed and critically discussed. There have ...been two conflicting views on the effect of the loose binding of the projectile on the fusion cross section. On the one hand one expects an enhancement of the fusion cross section due to the loose binding while, on the other hand, the easy breakup of the projectile is expected to inhibit the fusion cross section. We critically discuss these two aspects of loose binding by comparing the experimental results for a number of radioactive beams.
The data for
17F (where the last neutron binding energy
S
n=0.601
MeV), neither show breakup effects nor enhancement when compared with the fusion of the nucleus
19F. The data for a
6He beam (
S
2n=0.975
MeV) show enhancement, very strong in one case, and the strong breakup (BU)
+transfer cross section may be related to this. The fusion data obtained with the halo nucleus
11Be (
S
n=0.504
MeV) do not show enhancement below the barrier, compared with
9Be, and show moderate effects above the barrier. Moreover,
9Be (
S
n=1.665
MeV) shows a very strong BU
+transfer cross section as in the case of
6He, but this apparently has no direct effect on fusion. The data with the neutron-rich
38S,
29,31Al radioactive beams do not differ much from data with the stable
32S,
27Al, respectively. In conclusion we observe: (i) effects of loose binding in neutron skin nuclei but not with other halo nuclei, (ii) a reduction of the fusion cross section above the barrier due to breakup effects.
The various theoretical approaches developed up to now based on “simple” assumptions give opposite predictions for fusion, with some expecting enhancement of the cross section while others expect a hindrance of the cross section. However, most of these approaches do not correctly treat the transitions to the continuum which are expected to be induced easily in these weakly bound nuclei. It is necessary to develop a more complete and possibly “simple” theoretical treatment that incorporates the continuum coupling which will play an important role in subbarrier fusion.
The elastic scattering in the reaction
7
Li+
208
Pb was investigated in the bombarding energy range from 25 to 39 MeV. The real and imaginary parts of the optical potential were analyzed by using a ...phenomenological potential. A dispersion relation analysis is presented in order to investigate the threshold anomaly effect. It is concluded that
7
Li has an intermediate behavior between the tightly bound nuclei such as
16
O and the loosely bound nuclei such as
6
Li where the lack of the threshold anomaly is unambiguously observed. Reaction cross sections are also extracted from the elastic scattering data and its comparison with the ones of other systems has been performed to draw hints on the effect of the breakup channel.
.
We report on the development of a new, portable detector array for charged particles with a low detection threshold to study the reaction mechanisms of exotic nuclear systems at energies around the ...Coulomb barrier. In order to identify both light and heavy particles simultaneously, the array consists of ten units of
Δ
E
-
E
R
telescopes, where each one is made up of four detection layers: one ionization chamber, one 40 (or 60)μm double-sided silicon strip detector and two quadrant silicon detectors with thicknesses of 300μm and 1000 (or 1500)μm, respectively. The frame of the ionization chamber is innovatively designed with printed circuit boards, thus the mass of each telescopic unit was reduced significantly which eases transport and installation requirements to different radioactive ion beam lines around the globe. The commissioning experiments focused on elucidating several reaction mechanisms encountered in the
17
F +
58
Ni and
17
F +
208
Pb systems, and we demonstrated that the array has a sufficient capability to enable charged particle identification over a large range of
Z
. Light particles like
p
,
d
,
α
as well as heavy ions like
16
O and
17
F can be clearly distinguished. Considering these properties, this newly developed array enables in-depth investigation of the novel reaction mechanisms which are manifested in the collisions of exotic nuclei with differing isotopes.
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