Discrete social recommendation

National Research Foundation (NRF) Singapore under its AI Singapore Programm

Compositional coding for collaborative filtering

National Research Foundation (NRF) Singapore under its AI Singapore Programm

Direct imaging of fluorescence enhancement in the gap between two gold nanodisks

We present an analysis of the optical coupling between two gold nanodisks by near-field fluorescence microscopy. This is achieved by simultaneously scanning and measuring the light emitted by a single Er3þ/Yb3þ doped nanocrystal glued at the end of an atomic force microscope tip. The excitation of the nanocrystal was performed at k ¼ 975 nm via upconversion, and fluorescence was detected in the visible part of the spectrum at k ¼ 550 nm. For an isolated nanodisk, the near-field presents a two-lobe pattern oriented along the direction of the incident polarization. For two nanodisks with a sizable separation distance (385 nm) illuminated with the polarization along the interparticle axis, we observe a negative effect of the coupling with a slight decrease in fluorescence in the gap. For smaller gap values (195, 95, and 55 nm), a strong increase in fluorescence is observed as well as a reduced spatial localization of the field as the distance decreases. Finally, when the disks touch each other (0 nm), the dipolar–dipolar interaction between them disappears and no fluorescence enhancement occurs. A new plasmon mode is created at another wavelength. Our experimental results are in good agreement with numerical simulations of the nearfield intensity distribution at the excitation wavelength on the surface of the structures. Combining fluorescence mapping and far-field scattering spectroscopy should be of strong interest to develop bio-chemical sensors based on field enhancement effects.The authors thank the support from the DIM Nano-K program from “Region Ile de France,” from the Idex Paris Sciences & Lettres through Grant No. ANR-10-IDEX-0001-02 PSL from the CNRS and the CSIC through the Spanish-French program PICS (Grant Nos. SolarNano PICS07687 and PIC2016FR2), and from the Spanish Ministerio de Ciencia e Innovacion through Grant No. PID2019-109905GA-C22.Peer reviewe

Dicopper(I) Complexes Incorporating Acetylide-functionalized Pyridinyl-based Ligands::Synthesis, Structural and Photovoltaic Studies

Heteroaryl incorporated acetylide-functionalized pyridinyl ligands (<b>L1–L6</b>) with the general formula Py-CC-Ar (Py = pyridine and Ar = <i>thiophene-2-yl</i>, 2,2′<i>-bithiophene]-5-yl</i>, 2,2′<i>:5</i>′,2″<i>-terthiophene]-5-yl</i>, <i>thieno­[2,3-<i>b</i>]­thiophen-2-yl</i>, <i>quinoline-5-yl</i>, <i>benzo­[c]­[1,2,5]­thiadiazole-5-yl</i>) have been synthesized by Pd(0)/Cu­(I)-catalyzed cross-coupling reaction of 4-ethynylpyridine and the respective heteroaryl halide. Ligands <b>L1–L6</b> were isolated in respectable yields and characterized by microanalysis, IR spectroscopy, ¹H NMR spectroscopy, and ESI-MS mass spectrometry. A series of dinuclear Cu­(I) complexes <b>1</b>–<b>10</b> have been synthesized by reacting <b>L1–L6</b> with CuI and triphenylphosphine (PPh₃) (<b>R1</b>) or with an anchored phosphine derivative, 4-(diphenylphosphino) benzoic acid (<b>R2</b>)/2-(diphenylphosphino)­benzenesulfonic acid (<b>R3</b>), in a stoichiometric ratio. The complexes are soluble in common organic solvents and have been characterized by analytical, spectroscopic, and computational methods. Single-crystal X-ray structure analysis confirmed rhomboid dimeric structures for complexes <b>1</b>, <b>2</b>, <b>4</b>, and <b>5</b>, and a polymeric structure for <b>6</b>. Complexes <b>1</b>–<b>6</b> showed oxidation potential responses close to 0.9 V vs Fc^0/+, which were chemically irreversible and are likely to be associated with multiple steps and core oxidation. Preliminary photovoltaic (PV) results of these new materials indicated moderate power conversion efficiency (PCE) in the range of 0.15–1.56% in dye-sensitized solar cells (DSSCs). The highest PCE was achieved with complex <b>10</b> bearing the sulfonic acid anchoring functionality

BLOOM: A 176B-Parameter Open-Access Multilingual Language Model

Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Les applications des nanoparticules plasmoniques sur les générateurs photo-thermoélectriques hybrides flexibles

Dans cette thèse de doctorat, j'ai principalement étudié trois domaines : (1) La synthèse de nanoparticules (NPs) plasmoniques traitées en solution, qui servent de revêtements photothermiques et permettent la conversion entre lumière et chaleur. Ces revêtements à base de NP ont ensuite été appliqués pour augmenter la différence de température du dispositif thermoélectrique mentionné ci-dessous. (2) La réalisation et les caractérisations de générateurs photo-thermoélectriques hybrides organiques-inorganiques souples et portables (photo-TEGs). Ces photo-TEGs, combinant le revêtement de photothermique à base des NPs mentionné ci-dessus et les TEGs p-n hybrides soigneusement conçus, ont démontré une récupération d'énergie sous illumination solaire. (3) L'étude des matériaux thermoélectrique à base de Ag2Se dopés au soufre (S-dopés) de type n, proposant une nouvelle synthèse en solution à température ambiante (RT) et conduisant à une série de couches minces thermoélectriques et flexibles avec des propriétés optimisées. Ces films minces de Ag2Se S-dopés de type n ont ensuite été appliqués, démontrant une récupération d'énergie proche de la RT dans différentes situations. Pour présenter les résultats de cette thèse, six chapitres sont formés au total, parmi lesquels trois chapitres (Chapitre 3, 4 et 5) sont utilisés pour décrire les résultats obtenus concernant les trois aspects susmentionnés ainsi qu'une introduction (Chapitre 1), un chapitre expérimental (chapitre 2) et un chapitre de conclusion (chapitre 6). Enfin, une conclusion générale est donnée avec des perspectives sur le domaine de la technologie thermoélectrique flexibles, portable et à faible coût ainsi des textiles intelligents à récupération d'énergie.In this PhD thesis, I have mainly investigated three areas: (1) The synthesis of solution-processed plasmonic nanoparticles, which serve as photothermal coatings and enable light-heat conversion. These NP-based coatings were then applied to boost the temperature difference of the thermoelectric device undermentioned. (2) The realization and characterizations of flexible and wearable organic-inorganic hybrid photo-thermoelectric generators (photo-TEGs). These photo-TEGs, combining the above-mentioned photothermal NP coating and the carefully designed hybrid p-n TEGs, demonstrated energy harvest under solar illumination. (3) The investigation of n-type sulfur-doped (S-doped) Ag2Se TE materials, proposing a new room-temperature (RT) solution synthesis, and leading to a series of functional and flexible TE thin films with optimized TE properties. These n-type S-doped Ag2Se TE thin films were further applied demonstrating near-RT energy harvest in different situations. To present the results of this thesis, all together six chapters are formed, among which three chapters (Chapter 3, 4, and 5) are used to describe the results obtained concerning the above-mentioned three aspects together with an introduction (Chapter 1), an experimental (Chapter 2), and conclusion (Chapter 6) chapters. Finally, a general conclusion is given with perspectives on the field of low-cost and wearable thermoelectric technology as well as energy-harvesting smart textiles