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| 2. |
- Kruse, N., et al.
(author)
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Validation of a quantitative cerebrospinal fluid alpha-synuclein assay in a European-wide interlaboratory study
- 2015
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In: Neurobiology of Aging. - : Elsevier BV. - 0197-4580. ; 36:9, s. 2587-2596
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Journal article (peer-reviewed)abstract
- Decreased levels of alpha-synuclein (aSyn) in cerebrospinal fluid (CSF) in Parkinson's disease and related synucleinopathies have been reported, however, not consistently in all cross-sectional studies. To test the performance of one recently released human-specific enzyme-linked immunosorbent assay (ELISA) for the quantification of aSyn in CSF, we carried out a round robin trial with 18 participating laboratories trained in CSF ELISA analyses within the BIOMARKAPD project in the EU Joint Program -Neurodegenerative Disease Research. CSF samples (homogeneous aliquots from pools) and ELISA kits (one lot) were provided centrally and data reported back to one laboratory for data analysis. Our study showed that although factors such as preanalytical sample handling and lot-to-lot variability were minimized by our study design, we identified high variation in absolute values of CSF aSyn even when the same samples and same lots of assays were applied. We further demonstrate that although absolute concentrations differ between laboratories the quantitative results are comparable. With further standardization this assay may become an attractive tool for comparing aSyn measurements in diverse settings. Recommendations for further validation experiments and improvement of the interlaboratory results obtained are given. (C) 2015 Elsevier Inc. All rights reserved.
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| 3. |
- Ben Sedrine, N., et al.
(author)
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Fluctuating potentials in GaAs : Si nanowires: Critical reduction of the influence of polytypism on the electronic structure
- 2018
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 10:8, s. 3697-3708
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Journal article (peer-reviewed)abstract
- In this work, the effects of Si doping in GaAs nanowires (NWs) grown on GaAs (111)B by molecular beam epitaxy with different Si doping levels (nominal free carrier concentrations of 1 × 1016, 8 × 1016, 1 × 1018 and 5 × 1018 cm-3) are deeply investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), grazing incidence X-ray diffraction (GID), photoluminescence (PL) and cathadoluminescence (CL). TEM results reveal a mixture of wurtzite (WZ) and zinc-blende (ZB) segments along the NW axis independently of the Si doping levels. GID measurements suggest a slight increase of the ZB fraction with the Si doping. Low temperature PL and CL spectra exhibit sharp lines in the energy range 1.41-1.48 eV, for the samples with lower Si doping levels. However, the emission intensity increases and is accompanied by a clear broadening of the observed lines for the samples with higher Si doping levels. The staggered type-II band alignment only determines the optical properties of the lower doping levels in GaAs:Si NWs. For the higher Si doping levels, the electronic energy level structure of the NWs is determined by electrostatic fluctuating potentials intimately related to the amphoteric behavior of the Si dopant in GaAs. For the heavily doped NWs, the estimated depth of the potential wells is ∼96-117 meV. Our results reveal that the occurrence of the fluctuating potentials is not dependent on the crystalline phase and shows that the limitation imposed by the polytypism can be overcome.
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| 4. |
- Kehoe, Laura, et al.
(author)
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Make EU trade with Brazil sustainable
- 2019
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Journal article (other academic/artistic)
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| 5. |
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| 6. |
- Alberto, H. V., et al.
(author)
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Slow-muon study of quaternary solar-cell materials : Single layers and p-n junctions
- 2018
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In: Physical Review Materials. - : AMER PHYSICAL SOC. - 2475-9953. ; 2:2
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Journal article (peer-reviewed)abstract
- Thin films and p-n junctions for solar cells based on the absorber materials Cu(In, Ga) Se-2 and Cu2ZnSnS4 were investigated as a function of depth using implanted low energy muons. The most significant result is a clear decrease of the formation probability of the Mu(+) state at the heterojunction interface as well as at the surface of the Cu(In, Ga)Se-2 film. This reduction is attributed to a reduced bonding reaction of the muon in the absorber defect layer at its surface. In addition, the activation energies for the conversion from a muon in an atomiclike configuration to a anion-bound position are determined from temperature-dependence measurements. It is concluded that the muon probe provides a measurement of the effective surface defect layer width, both at the heterojunctions and at the films. The CIGS surface defect layer is crucial for solar-cell electrical performance and additional information can be used for further optimizations of the surface.
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| 7. |
- Fernandes, P. A., et al.
(author)
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Phase selective growth of Cu12Sb4S13 and Cu3SbS4 thin films by chalcogenization of simultaneous sputtered metal precursors
- 2019
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In: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 797, s. 1359-1366
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Journal article (peer-reviewed)abstract
- In this work, we present a procedure to grow Cu12Sb4S13 and Cu3SbS4 thin films consisting of the deposition of simultaneously sputtered metal precursors followed by a annealing treatment in a sulphur atmosphere. The selection of the ternary phase is performed by adjusting the sulphur evaporation temperature in the chalcogenization process. It is shown that for a sulphur evaporation temperature of 140 °C the predominant phase is Cu12Sb4S13 while for 180 °C the predominant phase is Cu3SbS4. In order to ensure precursor composition homogeneity, the Cu-Sb metallic precursors are deposited simultaneously by RF magnetron sputtering using adjustable segmented targets. The morphological characterization of the films was made by scanning electron microscopy and the composition was analysed by energy dispersive spectroscopy. The structural analysis and phase identification were performed by X-ray diffraction and Raman scattering. The optical properties were studied on films deposited directly on bare glass and the optical bandgap energies of 1.47 eV and 0.89 eV for Cu12Sb4S13 and Cu3SbS4, respectively, were determined.
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| 8. |
- Salvo, G, et al.
(author)
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International radical trachelectomy assessment: IRTA study
- 2019
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In: International journal of gynecological cancer : official journal of the International Gynecological Cancer Society. - : BMJ. - 1525-1438. ; 29:3, s. 635-638
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Journal article (peer-reviewed)abstract
- Radical trachelectomy is considered a viable option for fertility preservation in patients with low-risk, early-stage cervical cancer. Standard approaches include laparotomy or minimally invasive surgery when performing radical trachelectomy.Primary ObjectiveTo compare disease-free survival between patients with FIGO (2009) stage IA2 or IB1 (≤2cm) cervical cancer who underwent open versus minimally invasive (laparoscopic or robotic) radical trachelectomy.Study HypothesisWe hypothesize that minimally invasive radical trachelectomy has similar oncologic outcomes to those of the open approach.Study DesignThis is a collaborative, multi-institutional, international, retrospective study. Patients who underwent a radical trachelectomy and lymphadenectomy between January 1, 2005 and December 31, 2017 will be included. Institutional review board approval will be required. Each institution will be provided access to a study-specific REDCap (Research Electronic Data Capture) database maintained by MD Anderson Cancer Center and will be responsible for entering patient data.Inclusion CriteriaPatients with squamous, adenocarcinoma, or adenosquamous cervical cancer FIGO (2009) stages IA2 and IB1 (≤2 cm) will be included. Surgery performed by the open approach or minimally invasive approach (laparoscopy or robotics). Tumor size ≤2 cm, by physical examination, ultrasound, MRI, CT, or positron emission tomography (at least one should confirm a tumor size ≤2 cm). Centers must contribute at least 15 cases of radical trachelectomy (open, minimally invasive, or both).Exclusion CriteriaPrior neoadjuvant chemotherapy or radiotherapy to the pelvis for cervical cancer at any time, prior lymphadenectomy, or pelvic retroperitoneal surgery, pregnant patients, aborted trachelectomy (intra-operative conversion to radical hysterectomy), or vaginal approach.Primary EndpointThe primary endpoint is disease-free survival measured as the time from surgery until recurrence or death due to disease. To evaluate the primary objective, we will compare disease-free survival among patients with FIGO (2009) stage IA2 or IB1 (≤2cm) cervical cancer who underwent open versus minimally invasive radical trachelectomy.Sample SizeAn estimated 535 patients will be included; 256 open and 279 minimally invasive radical trachelectomy. Previous studies have shown that recurrence rates in the open group range from 3.8% to 7.6%. Assuming that the 4.5-year disease-free survival rate for patients who underwent open surgery is 95.0%, we have 80% power to detect a 0.44 HR using α level 0.10. This corresponds to an 89.0% disease-free survival rate at 4.5 years in the minimally invasive group.
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| 9. |
- Bose, Sourav, et al.
(author)
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A morphological and electronic study of ultrathin rear passivated Cu(In,Ga)Se2 solar cells
- 2019
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 671, s. 77-84
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Journal article (peer-reviewed)abstract
- The effects of introducing a passivation layer at the rear of ultrathin Copper Indium Gallium di-Selenide Cu(In,Ga)Se2 (CIGS) solar cells is studied. Point contact structures have been created on 25 nm Al2O3 layer using e-beam lithography. Reference solar cells with ultrathin CIGS layers provide devices with average values of light to power conversion efficiency of 8.1% while for passivated cells values reached 9.5%. Electronic properties of passivated cells have been studied before, but the influence of growing the CIGS on Al2O3 with point contacts was still unknown from a structural and morphological point of view. Scanning Electron Microscopy, X-ray Diffraction and Raman spectroscopy measurements were performed. These measurements revealed no significant morphological or structural differences in the CIGS layer for the passivated samples compared with reference samples. These results are in agreement with the similar values of carrier density (~8 x 1016 cm-3) and depletion region (~160 nm) extracted using electrical measurements. A detailed comparison between both sample types in terms of current-voltage, external quantum efficiency and photoluminescence measurements show very different optoelectronic behaviour which is indicative of a successful passivation. SCAPS simulations are done to explain the observed results in view of passivation of the rear interface.
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| 10. |
- Cunha, J. M. V., et al.
(author)
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Insulator Materials for Interface Passivation of Cu(In,Ga)Se-2 Thin Films
- 2018
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In: IEEE Journal of Photovoltaics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2156-3381 .- 2156-3403. ; 8:5, s. 1313-1319
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Journal article (peer-reviewed)abstract
- In this work, metal-insulator-semiconductor structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al2O3), silicon nitride, and silicon oxide (SiOx) to be used as passivation layers in Cu(In,Ga)Se-2 (CIGS) thin-film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance versus conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q(f)). The density of interface defects (D-it) was estimated from capacitance versus conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 degrees C) and the use of a sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiOx deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower Dit values was Al2O3 when deposited by sputtering.
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