Sound localization in noisy contexts: performance, metacognitive evaluations and head movements.

Localizing sounds in noisy environments can be challenging. Here, we reproduce real-life soundscapes to investigate the effects of environmental noise on sound localization experience. We evaluated participants' performance and metacognitive assessments, including measures of sound localization effort and confidence, while also tracking their spontaneous head movements.

Metacognition for hearing in noise: a comparison between younger and older adults.

Metacognition entails knowledge of one's own cognitive skills, perceived self-efficacy and locus of control when performing a task, and performance monitoring. Age-related changes in metacognition have been observed in metamemory, whereas their occurrence for hearing remained unknown. We tested 30 older and 30 younger adults with typical hearing, to assess if age reduces metacognition for hearing sentences in noise.

The effect of face masks on sign language comprehension: performance and metacognitive dimensions.

In spoken languages, face masks represent an obstacle to speech understanding and influence metacognitive judgments, reducing confidence and increasing effort while listening. To date, all studies on face masks and communication involved spoken languages and hearing participants, leaving us with no insight on how masked communication impacts on non-spoken languages. Here, we examined the effects of face masks on sign language comprehension and metacognition.

Spontaneous head-movements improve sound localization in aging adults with hearing loss.

Moving the head while a sound is playing improves its localization in human listeners, in children and adults, with or without hearing problems. It remains to be ascertained if this benefit can also extend to aging adults with hearing-loss, a population in which spatial hearing difficulties are often documented and intervention solutions are scant. Here we examined performance of elderly adults (61-82 years old) with symmetrical or asymmetrical age-related hearing-loss, while they localized sounds with their head fixed or free to move.

Unmasking the Difficulty of Listening to Talkers With Masks: lessons from the COVID-19 pandemic.

Interactions with talkers wearing face masks have become part of our daily routine since the beginning of the COVID-19 pandemic. Using an on-line experiment resembling a video conference, we examined the impact of face masks on speech comprehension. Typical-hearing listeners performed a speech-in-noise task while seeing talkers with visible lips, talkers wearing a surgical mask, or just the name of the talker displayed on screen.

Can visual capture of sound separate auditory streams?

In noisy contexts, sound discrimination improves when the auditory sources are separated in space. This phenomenon, named Spatial Release from Masking (SRM), arises from the interaction between the auditory information reaching the ear and spatial attention resources. To examine the relative contribution of these two factors, we exploited an audio-visual illusion in a hearing-in-noise task to create conditions in which the initial stimulation to the ears is held constant, while the perceived separation between speech and masker is changed illusorily (visual capture of sound).

Covalent modification of franckeite with maleimides: connecting molecules and van der Waals heterostructures.

The building of van der Waals heterostructures and the decoration of 2D materials with organic molecules share a common goal: to obtain ultrathin materials with tailored properties. Performing controlled chemistry on van der Waals heterostructures would add an extra level of complexity, providing a pathway towards 2D-2D-0D mixed-dimensional heterostructures. Here we show that thiol-ene-like "click" chemistry can be used to decorate franckeite, a naturally occurring van der Waals heterostructure with maleimide reagents.

Functional Carbon Quantum Dots as Medical Countermeasures to Human Coronavirus.

Therapeutic options for the highly pathogenic human coronavirus (HCoV) infections are urgently needed. Anticoronavirus therapy is however challenging, as coronaviruses are biologically diverse and rapidly mutating. In this work, the antiviral activity of seven different carbon quantum dots (CQDs) for the treatment of human coronavirus HCoV-229E infections was investigated.

Mild Covalent Functionalization of Transition Metal Dichalcogenides with Maleimides: A "Click" Reaction for 2H-MoS and WS.

The physical properties of ultrathin transition metal dichalcogenides (2D-TMDCs) make them promising candidates as active nanomaterials for catalysis, optoelectronics, and biomedical applications. Chemical modification of TMDCs is expected to be key in modifying/adding new functions that will help make such promise a reality. We present a mild method for the modification of the basal planes of 2H-MoS and WS.

Simultaneous assembly of van der Waals heterostructures into multiple nanodevices.

van der Waals heterostructures (vdWH) are made of different two-dimensional (2D) layers stacked on top of each other, forming a single material with unique properties that differ from those of the individual 2D constituent layers, and that can be modulated through the interlayer interaction. These hetero-materials can be artificially made by mechanical stamping, solution processing or epitaxial growth. Alternatively, franckeite has been recently described as an example of a naturally-occurring vdWH that can be exfoliated down to nanometer thicknesses.

Characterization of highly crystalline lead iodide nanosheets prepared by room-temperature solution processing.

Two-dimensional (2D) semiconducting materials are particularly appealing for many applications. Although theory predicts a large number of 2D materials, experimentally only a few of these materials have been identified and characterized comprehensively in the ultrathin limit. Lead iodide, which belongs to the transition metal halides family and has a direct bandgap in the visible spectrum, has been known for a long time and has been well characterized in its bulk form.

Dielectrophoretic assembly of liquid-phase-exfoliated TiS nanoribbons for photodetecting applications.

Liquid-phase exfoliation is a technique capable of producing large quantities of two-dimensional materials in suspension. Despite many efforts in the optimization of the exfoliation process itself, not much has been done towards the integration of liquid-phase-exfoliated materials in working solid-state devices. In this article, we use dielectrophoresis to direct the assembly of liquid-phase-exfoliated TiS nanoribbons between two gold electrodes to produce photodetectors working in the visible region.

Surfactant-Free Polar-to-Nonpolar Phase Transfer of Exfoliated MoS Two-Dimensional Colloids.

Exfoliation of lamellar materials into their corresponding layers represented a breakthrough, owing to the outstanding properties arising from the nanometric thickness confinement. Among the cleavage techniques, liquid-phase exfoliation is now on the rise because it is scalable and leads to easy-to-manipulate colloids. However, all appropriate exfoliating solvents exhibit strong polarity, which greatly restricts the scope of feasible functionalization or processing of the resulting flakes.

Franckeite as a naturally occurring van der Waals heterostructure.

The fabrication of van der Waals heterostructures, artificial materials assembled by individual stacking of 2D layers, is among the most promising directions in 2D materials research. Until now, the most widespread approach to stack 2D layers relies on deterministic placement methods, which are cumbersome and tend to suffer from poor control over the lattice orientations and the presence of unwanted interlayer adsorbates. Here, we present a different approach to fabricate ultrathin heterostructures by exfoliation of bulk franckeite which is a naturally occurring and air stable van der Waals heterostructure (composed of alternating SnS-like and PbS-like layers stacked on top of each other).

Unraveling the time cross correlations of an emitter switching between two states with the same fluorescence intensity.

The autocorrelation function of the fluorescence intensity of a nanoemitter is measured with the standard Hanbury-Brown and Twiss setup. Time-tagging of the photodetection events during all the experiment has opened new possibilities in terms of post-selection techniques that enable to go beyond the blinking and antibunching characterization. Here, we first present a new method developed to investigate in detail the antibunching of a fluorophore switching between two emitting states.

Oriented Bioconjugation of Unmodified Antibodies to Quantum Dots Capped with Copolymeric Ligands as Versatile Cellular Imaging Tools.

Distinctive optical properties of inorganic quantum dot (QD) nanoparticles promise highly valuable probes for fluorescence-based detection methods, particularly for in vivo diagnostics, cell phenotyping via multiple markers or single molecule tracking. However, despite high hopes, this promise has not been fully realized yet, mainly due to difficulties at producing stable, nontoxic QD bioconjugates of negligible nonspecific binding. Here, a universal platform for antibody binding to QDs is presented that builds upon the controlled functionalization of CdSe/CdS/ZnS nanoparticles capped with a multidentate dithiol/zwitterion copolymer ligand.

Sulfobetaine-Vinylimidazole Block Copolymers: A Robust Quantum Dot Surface Chemistry Expanding Bioimaging's Horizons.

Long-term inspection of biological phenomena requires probes of elevated intra- and extracellular stability and target biospecificity. The high fluorescence and photostability of quantum dot (QD) nanoparticles contributed to foster their promise as bioimaging tools that could overcome limitations associated with traditional fluorophores. However, QDs' potential as a bioimaging platform relies upon a precise control over the surface chemistry modifications of these nano-objects.

Non-blinking quantum dot with a plasmonic nanoshell resonator.

Colloidal semiconductor quantum dots are fluorescent nanocrystals exhibiting exceptional optical properties, but their emission intensity strongly depends on their charging state and local environment. This leads to blinking at the single-particle level or even complete fluorescence quenching, and limits the applications of quantum dots as fluorescent particles. Here, we show that a single quantum dot encapsulated in a silica shell coated with a continuous gold nanoshell provides a system with a stable and Poissonian emission at room temperature that is preserved regardless of drastic changes in the local environment.

Time-gated cell imaging using long lifetime near-infrared-emitting quantum dots for autofluorescence rejection.

Fluorescence imaging is a promising technique for the detection of individual cell migration. Its sensitivity is, however, limited by a high tissue autofluorescence and a poor visible light penetration depth. In order to solve this problem, the fluorescence signal peak wavelength should lie in an absorption and diffusion free region and should be distinguishable, either spectrally or temporally, from the autofluorescence background.

Synthesis of fluorinated catharanthine analogues and investigation of their biomimetic coupling with vindoline.

The syntheses of 20,20-difluorocatharanthine and congeners, starting from the naturally occurring catharanthine, are reported. The fluorinated catharanthine analogues were investigated as potential precursors to dimeric Vinca alkaloids of the vinflunine family. However, the biomimetic coupling of the fluorinated catharanthine derivatives with vindoline led to unexpected alkaloid structures, the formation of which was rationalized.

Influence of luminescence quantum yield, surface coating, and functionalization of quantum dots on the sensitivity of time-resolved FRET bioassays.

In clinical diagnostics, homogeneous time-resolved (TR) FRET immunoassays are used for fast and highly sensitive detection of biomarkers in serum samples. The most common immunoassay format is based on europium chelate or cryptate donors and allophycocyanin acceptors. Replacing europium donors with terbium complexes and the acceptors with QDs offers large photophysical advantages for multiplexed diagnostics, because the Tb-complex can be used as FRET donor for QD acceptors of different colors.

Highly enhanced affinity of multidentate versus bidentate zwitterionic ligands for long-term quantum dot bioimaging.

High colloidal stability in aqueous conditions is a prerequisite for fluorescent nanocrystals, otherwise known as "quantum dots", intended to be used in any long-term bioimaging experiment. This essential property implies a strong affinity between the nanoparticles themselves and the ligands they are coated with. To further improve the properties of the bidentate monozwitterionic ligand previously developed in our team, we synthesized a multidentate polyzwitterionic ligand, issued from the copolymerization of a bidentate monomer and a monozwitterionic one.