Precise organization of metallic and semiconducting particles of small dimensionality and over large scales is a challenging requirement at the basis of many photonic, electronic, and catalytic ...devices. Here, we demonstrate a new approach, all based on self-assembly, for the ordering of 2D arrays of nanodots over several cm2 sized, crystalline silicon wafers. Via block copolymer-micelles-assisted sol–gel deposition of TiO2 on Si and thermal annealing, we prepare the substrates with inorganic nanopatterns featuring hexagonally positioned perforations homogeneously sized and spaced. These templates are used to selectively form individual nanodots in each perforation featuring typical size of 17 ± 2 nm for the Ge and 28 ± 5 nm for the Au particles. The process developed in this study paves the way to a scalable self-organization of nanoparticles for various applications. We mainly focused on the use of Ge dots as quantum dots for optoelectronic applications, proving the high crystalline quality of the system. But we also demonstrate that the process can be applied to Au dots, often used as catalyst for vapor–liquid–solid growth of nanowires or plasmonic particles.
Extending plasmonics into the ultraviolet range imposes the use of aluminum to achieve the best optical performance. However, water corrosion is a major limitation for UV aluminum plasmonics, as this ...phenomenon occurs significantly faster in the presence of UV light, even at low laser powers of a few microwatts. Here, we assess the performance of nanometer-thick layers of various metal oxides deposited by atomic layer deposition (ALD) and plasma-enhanced chemical vapor deposition (PECVD) on top of aluminum nanoapertures to protect the metal against UV photocorrosion. The combination of a 5 nm Al2O3 layer covered by a 5 nm TiO2 capping provides the best resistance performance, while a single 10 nm layer of SiO2 or HfO2 is a good alternative. We also report the influence of the laser wavelength, the laser operation mode, and the pH of the solution. Appropriately choosing these conditions significantly extends the range of optical powers for which the aluminum nanostructures can be used. As an application, we demonstrate the label-free detection of streptavidin proteins with an improved signal-to-noise ratio. Our approach is also beneficial to promote the long-term stability of aluminum nanostructures. Finding the appropriate nanoscale protection against aluminum corrosion is the key to enabling the development of UV plasmonic applications in chemistry and biology.
Zero-mode waveguide (ZMW) nano-apertures milled in metal films were proposed to improve the Förster resonance energy transfer (FRET) efficiency and enable single-molecule FRET detection beyond the ...10 nm barrier, overcoming the restrictions of diffraction-limited detection in a homogeneous medium. However, the earlier ZMW demonstrations were limited to the Atto 550–Atto 647N fluorophore pair, asking the question whether the FRET enhancement observation was an artifact related to this specific set of fluorescent dyes. Here, we use Alexa Fluor 546 and Alexa Fluor 647 to investigate single-molecule FRET at large donor–acceptor separations exceeding 10 nm inside ZMWs. These Alexa fluorescent dyes feature a markedly different chemical structure, surface charge, and hydrophobicity as compared to their Atto counterparts. Our single molecule data on Alexa 546–Alexa 647 demonstrate enhanced FRET efficiencies at large separations exceeding 10 nm, extending the spatial range available for FRET and confirming the earlier conclusions. By showing that the FRET enhancement inside a ZMW does not depend on the set of fluorescent dyes, this report is an important step to establish the relevance of ZMWs to extend the sensitivity and detection range of FRET, while preserving its ability to work on regular fluorescent dye pairs.
In the 2000s, the government of Burundi and the United Nations created villages to permanently reintegrate over 5,000 uprooted families. Most of these ‘Peace Villages’ soon became areas of ...socio-economic instability. The dominant narrative blames inefficient aid coordination, while returnees deplore their marginalization in the process and in local communities. The idea of villages epitomizing ‘development’, economic interests in building villages and the rhetoric of Burundi as a successful peace-building story may explain why villagization kept being presented as a solution. Above all, the problem is conceptual: the Peace Villages programmes (i) mixed up the causes and consequences of sustainable economic development and reintegration and (ii) recognized land as identity-giving but mistakenly assumed that it would also provide for the livelihood of the returnees. Durable solutions for uprooted returnees need to allow them agency in their own reintegration process, capitalize on their socio-economic skills, and engage with local communities and development initiatives.
Strain engineering is seen as a cost-effective way to improve the properties of electronic devices. However, this technique is limited by the development of the Asarro Tiller Grinfeld growth ...instability and nucleation of dislocations. Two strain engineering processes have been developed, fabrication of stretchable nanomembranes by deposition of SiGe on a sacrificial compliant substrate and use of lateral stressors to strain SiGe on Silicon On Insulator. Here, we investigate the influence of substrate softness and pre-strain on growth instability and nucleation of dislocations. We show that while a soft pseudo-substrate could significantly enhance the growth rate of the instability in specific conditions, no effet is seen for SiGe heteroepitaxy, because of the normalized thickness of the layers. Such results were obtained for substrates up to 10 times softer than bulk silicon. The theoretical predictions are supported by experimental results obtained first on moderately soft Silicon On Insulator and second on highly soft porous silicon. On the contrary, the use of a tensily pre-strained substrate is far more efficient to inhibit both the development of the instability and the nucleation of misfit dislocations. Such inhibitions are nicely observed during the heteroepitaxy of SiGe on pre-strained porous silicon.
Summary
Sickle cell disease (SCD) is characterised by chronic haemolysis and oxidative stress. Herein, we investigated 30 SCD patients and found 40% with elevated mitochondria levels (SS‐mito+) in ...their mature red blood cells, while 60% exhibit similar mitochondria levels compared to the AA group (SS‐mito−). The SS‐mito+ patients are characterised by higher reticulocytosis and total bilirubin levels, lower foetal haemoglobin, and non‐functional mitochondria. Interestingly, we demonstrated decreased levels of mitophagy inducers, PINK1 and NIX, and higher levels of HSP90 chaperone in their red cells. Our results highlighted for the first time an abnormal retention of mitochondria in SCD linked with mitophagy‐related proteins.
Materials featuring anomalous suppression of density fluctuations over large length scales are emerging systems known as disordered hyperuniform. The underlying hidden order renders them appealing ...for several applications, such as light management and topologically protected electronic states. These applications require scalable fabrication, which is hard to achieve with available top-down approaches. Theoretically, it is known that spinodal decomposition can lead to disordered hyperuniform architectures. Spontaneous formation of stable patterns could thus be a viable path for the bottom-up fabrication of these materials. Here, we show that monocrystalline semiconductor-based structures, in particular Si1−x Gex layers deposited on silicon-on-insulator substrates, can undergo spinodal solid-state dewetting featuring correlated disorder with an effective hyperuniform character. Nano- to micrometric sized structures targeting specific morphologies and hyperuniform character can be obtained, proving the generality of the approach and paving the way for technological applications of disordered hyperuniform metamaterials. Phase-field simulations explain the underlying nonlinear dynamics and the physical origin of the emerging patterns.
BackgroundThe coronavirus disease 2019 (COVID-19) global pandemic is a highly stressful event that may contribute to psychological symptoms, particularly in patients with pre-existing chronic ...conditions. This study examined COVID-19 pandemic related stress experienced by patients with systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA) and its association with symptoms of psychological distress.MethodsAn on-line cross-sectional survey study was conducted with 55 SLE (mean age = 54.8, ±13.8) and 42 RA (mean age = 64.2, ±12.2) patients recruited from a tertiary care centre in Quebec City between May 25, 2021 and June 13, 2021. Participants completed the COVID-19 Stressors Questionnaire adapted by our team for inflammatory arthritis. The Impact of Event Scale-Revised (IES-R) assessed post-traumatic stress symptoms (PTSS) caused by the COVID-19 pandemic. The Patient Health Questionnaire-8 (PHQ-8) and the Generalized Anxiety Disorder-7 (GAD-7) measured symptoms of depression and anxiety, respectively.ResultsAmong respondents 3/97 had been diagnosed with COVID-19 since the start of the pandemic (SLE=2, RA=1). Clinically significant PTSS (IES-R score ≥24) due to the COVID-19 pandemic was reported by 13.4% of participants, with no statistically significant difference between both disease groups (SLE = 16.4%; RA=9.5%). The degree of concern related to COVID-19 stressors were similar in both disease groups (SLE: M = 10.0 ±8.2; RA: M = 8.7 ±9.5). As shown in table 1, COVID-19 stressors that were associated with the highest degree of concerns were: having a loved one contract coronavirus (SLE 50.9%; RA 28.6%), the possibility of contracting (SLE 45.5%; RA 35.7%) or getting sick from coronavirus (SLE 40%; RA 21.4%), working in a place with high likelihood of exposure (SLE 30.9%; RA 21.4%), and the possibility of their disease worsening or being poorly managed due to changes in medical care (SLE 27.3%; RA 26.2%). In patients with SLE, a higher level of concern related to COVID-19 stressors was significantly correlated with greater symptoms of PTSS (r = 0.46, p < 0.001), depression (r = 0.46, p < 0.001) and anxiety (r = 0.62, p < 0.001). In patients with RA, a higher level of concerns related to COVID-19 stressors was significantly correlated with greater symptoms of PTSS (r = 0.33, p -0.036), but not with symptoms of depression and anxiety.Abstract 1202 Table 1Degree of Concerns related to COVID-19 Stressors for Patients with SLE or RA COVID-19 Stressors All Participantsn=97n (%) SLEn=55n (%) RAn=42n (%) Having loved ones who contracts coronavirus 40 (41.2) 28 (50.9) 12 (28.6) Possibility of contracting coronavirus 40 (41.2) 25 (45.5) 15 (35.7) Getting sick from exposure to coronavirus 31 (32) 22 (40) 9 (21.4) Working in a place likely to be exposed to the coronavirus. 26 (26.8) 17 (30.9) 9 (21.4) Possibility of condition worsening or being poorly managed due to changes in medical care 26 (26.8) 15 (27.3) 11 (26.2) Postponement or cancellation of diagnostic and disease monitoring tests 19 (19.6) 10 (18.2) 9 (21.4) Increased responsibilities at home 19 (19.6) 11 (20) 8 (19.0) Difficulty obtaining food, medicine and other essentials 16 (16.5) 9 (16.4) 7 (16.7) Changes in treatments due coronavirus pandemic 15 (15.5) 9 (16.4) 6 (14.3) Postponement or cancellation of medical visits 15 (15.5) 9 (16.4) 6 (14.3) Difficulty obtaining help or social support needed 12 (12.4) 8 (14.5) 4 (9.5) Losing a job or experiencing a drop in income related to the coronavirus pandemic 10 (10.3) 5 (9.1) 5 (11.9) Responses rated on a scale of 0 “not at all” to 4 “extremely” concerned or worried. Responses dichotomized such that a threshold of 2 or higher represent greater concern/worry.ConclusionsStressors related to the COVID-19 pandemic are experienced by an important proportion of patients with SLE and RA and are associated with psychological symptoms, particularly for patients with SLE.
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