Ion irradiation is a powerful and affordable tool to rapidly test a wide range of irradiation conditions and make the link with the corresponding microstructural evolution. However, several issues of ...transferability of results from ion to neutron irradiation have been evidenced. This paper presents an atom probe investigation of the microstructural evolution of FeCr-NiSiP alloys with different contents of Cr and minor solutes under both ion and neutron irradiation at 300°C. Minor solutes and Cr are known to form solute rich clusters (SRCs) and α' clusters in ferritic and martensitic FeCr alloys, which are one of the causes of hardening. The objective of this work is to highlight the differences and the commonalities between ion and neutron irradiations in these alloys. The use of two ion beam energies (8 MeV and 5 MeV) revealed that this parameter has an impact on the formation of SRCs. The SRCs present similar characteristics after 8 MeV Fe ion irradiation and neutron irradiation, despite the different dose rate, when Ni, Si and P are present. It is not the case for 5 MeV Fe ions, for which the SRCs were less developed. Influence of the concentration of minor elements has been evidenced, as well. The presence of Ni, Si and P has been shown to impact both the number density and the size of SRCs in Fe9Cr-NiSiP alloys and the onset of α' formation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this study was to determine hepatitis co-infection in a cohort of HIV infected patients at their inclusion in the Senegalese Initiative of ART Access. B, C, and D Hepatitis viruses ...serological markers were checked retrospectively on 363 stored plasma. For HBV, the Abbott laboratories equipment IMx was used to detect HBs Ag and anti Core Ab on negative HBs Ag samples. For HDV, anti Delta Ab was performed using the Abbott Murex Kit on all HBs Ag positive samples. For HCV, anti HCV Ab was detected by IMx as double screening test and confirmed by INNO-LIATM HCV Core of Innogenetics laboratories. The statistical analysis was done with STATA V8. The study population was composed of 164 men and 199 women aged between 16 and 66 years. The immune and virological markers averages at their enrolment were 154 cell/mm³ for TLCD4+ (n = 355 patients) and 4.9 log for viral load (n = 277 patients). HBs Ag was found in 61 patients or 16.8% and the prevalence of anti-HBc Ab was 83.2% (252/295). 2 patients or 3% on HBs Ag positive sample presents HBV/HDV co-infection Ab anti HCV was detects in 6 patients or 1.6% after confirmation and 2 patients had triple infection with HBV. These results showed that the prevalence of HBV and HCV in the population of persons living with HIV/AIDS in Senegal is similar to that found in the general population. Our data indicated that hepatitis pathology in the PLwHIV was essentially due to HBV. Further studies are needed to diagnose occult hepatitis in order to set up therapeutic strategies taking into account co-infections by hepatitis viruses in the ART programmes. J. Med. Virol. 80:1332-1336, 2008.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
This paper focuses on the 3D MHD modeling of an arc plasma at industrial level; the torch is a 'Kvaerner-type' one, made of two concentric graphite electrodes and where spots are displaced with an ...external magnetic field. Different phenomenologies in arc movement were observed, ranging from a gliding arc on electrodes surfaces to hopping arc foots, agreeing with previous experimental works at atmospheric pressure. These dynamics have non-negligible consequences in the plasma process: the hopping mode induces more erosion due to a higher heat flux at the electrodes surfaces in comparison to the gliding arc; the latter mode results also in a strong gas swirling inside the torch, thus longer particles residence time is predicted.
This paper focuses on the 3D MHD modeling of a very high-pressure (20 bar) arc plasma at industrial level; the torch is a 'Kvaerner-type' one, made of two concentric graphite electrodes and where ...spots are displaced with an external magnetic field. Different phenomenologies in arc movement were observed, ranging from a gliding arc on electrodes surfaces to hopping arc foots and notably impacting electrodes erosion and the overall efficiency in the plasma process. Besides those dynamics which are indebted to torch configuration, current and flow rates, arc stability is also investigated with a theoretical model based on an energy principle. This research work provides new insight on the dynamics and stability of the arc inside the Kvaerner-type torch along with an unprecedented understanding of the very high pressure arc under concentric-electrodes-configuration, highlighting strong deformations due to pressure-driven instabilities for the high power arc.
The recent discovery and spectroscopic measurements of
O
27
and
O
28
suggests the disappearance of the
N
=
20
shell structure in these neutron-rich oxygen isotopes.
We measured one- and two-proton ...removal cross sections from
F
27
and
Ne
29
, respectively, extracting spectroscopic factors and comparing them to shell model overlap functions coupled with eikonal reaction model calculations.
The invariant mass technique was used to reconstruct the two-body (
O
24
+
n
) and three-body (
O
24
+
2
n
) decay energies from knockout reactions of
F
27
(106.2 MeV/u) and
Ne
29
(112.8 MeV/u) beams impinging on a
Be
9
target.
The one-proton removal from
F
27
strongly populated the ground state of
O
26
and the extracted cross section of
3
.
4
−
1.5
+
0.3
mb agrees with eikonal model calculations that are normalized by the shell model spectroscopic factors and account for the systematic reduction factor observed for single nucleon removal reactions within the models used. For the two-proton removal reaction from
Ne
29
an upper limit of 0.08 mb was extracted for populating states in
O
27
decaying though the ground state of
O
26
.
The measured upper limit for the population of the ground state of
O
26
in the two-proton removal reaction from
Ne
29
indicates a significant difference in the underlying nuclear structure of
F
27
and
Ne
29
.
Published by the American Physical Society
2024
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
8.
New segmented target for studies of neutron unbound systems Redpath, T.; Baumann, T.; Brown, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2020, Volume:
977, Issue:
C
Journal Article
Peer reviewed
Open access
The study of neutron-unbound systems using invariant mass spectroscopy is often performed using low-intensity radioactive ion beams. Low reaction yields can be countered by using thick targets but at ...the expense of larger uncertainties in the reconstructed invariant mass. We present a new segmented target designed to address this trade-off. It is composed of three ∼4 mm thick passive beryllium targets interleaved between four 140μm thick position sensitive silicon detectors. In the first experiment to use this new system the half-life of two-neutron unbound 26O was measured to be T1∕2=5.0−2.2+1.7 (stat)±1.7 (syst) ps, which agrees with a previous measurement made by the MoNA Collaboration.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To evaluate survival and investigate causes of death among HIV-1 infected adults receiving HAART in Senegal.
An observational prospective cohort.
Mortality was assessed in the first patients enrolled ...between August 1998 and April 2002 in the Senegalese antiretroviral drug access initiative. First-line regimen combined two nucleoside reverse transcriptase inhibitors and either a non-nucleoside reverse transcriptase inhibitor or a protease inhibitor. The most likely causes of death were ascertained through medical records or post-mortem interviews (verbal autopsy).
Four hundred and four patients (54.7% women) were enrolled in the study and were followed for a median of 46 months (interquartile range: 32-57 months) after HAART initiation. At baseline, 5% were antiretroviral therapy (ART) non-naive, 39 and 55% were respectively at CDC stage B and C, median age, CD4 cell count and viral load were 37 years, 128 cells/microl and 5.2 log cp/ml, respectively. Ninety-three patients died during follow-up and the overall incidence rate of death was 6.3/100 person-years 95% confidence interval (CI), 5.2-7.7. During the first year after HAART initiation, 47 patients died and seven were lost to follow-up, yielding to a probability of dying of 11.7% (95% CI, 8.9-15.3%). The death rate, which was highest during the first year after HAART initiation, decreased with time yielding a cumulative probability of dying of 17.4% (95% CI, 13.9-21.5%) and 24.6% (95% CI, 20.4-29.4%) at 2 and 5 years. Causes of death were ascertained in 76 deaths. Mycobacterial infections, neurotropic infections and septicaemia were the most frequent likely causes of death.
This study underlines the early mortality pattern after HAART initiation and highlights the leading role of mycobacterial infections in the causes of death.
OBJECTIVES:To assess the long-term survival, as well as the immunologic and virologic effectiveness, adherence, and drug resistance, in HIV-infected patients receiving highly active antiretroviral ...therapy (HAART) in one of the oldest and best-documented African cohorts.
METHODS:A prospective observational cohort study included the first 176 HIV-1-infected adults followed in the Senegalese government-sponsored antiretroviral therapy initiative launched in August 1998. Patients were followed for a median of 30 months (interquartile range, 21-36 months). HAART comprised 2 nucleoside reverse transcriptase inhibitors and either 1 protease inhibitor or 1 nonnucleoside reverse transcriptase inhibitor.
RESULTS:At baseline, 92% of patients were antiretroviral naive and 82% had AIDS; the median CD4 count was 144 cells/mm, and median viral load was 202,368 copies/mL. The survival probability was high (0.81 at 3 years; 95% CI, 0.74-0.86) and was independently related to a baseline hemoglobin level <10 g/dL and a Karnofsky score <90%. Antiviral efficacy was consistently observed during the 3 years of treatment (−2.5 to −3.0 log10 copies/mL; 60-80% of patients with viral load <500 copies/mL) and the CD4 count increase reached a median of 225 cells/mm. Most patients reported good adherence (80-90%). The emergence of drug resistance was relatively rare (12.5%).
CONCLUSION:This study shows that clinical and biologic results similar to those seen in Western countries can be achieved and sustained during the long term in Africa.
PDF
