Spatial Separation Research Articles

Linguistic Processing of Unattended Speech Under a Cocktail Party Listening Scenario.

In the context of a cocktail party listening environment, the processing of different linguistic hierarchy levels in unattended speech and their influence on target speech recognition remain controversial. This study aims to investigate how different levels of linguistic structures (such as syllable, word, and sentence) in competing speech influence the recognition of target speech in a speech-to-speech masking situation. Thirty-six participants were instructed to recognize target speech when it was masked by competing speech varied in masking types across syllables, words, and sentence. The perceived spatial location was altered to examine the interaction between linguistic unmasking effects and spatial unmasking effects. Recognition performance (i.e., intelligibility threshold) was determined by fitting psychometric functions to the recognition accuracies across four signal-to-noise ratios (-14, -10, -6, and - 2 dB) to evaluate each subject's ability to cope with challenging listening conditions. We revealed a significant decline in target speech recognition when the masking speech was linguistically structured and intelligible. Specifically, masking speech with higher linguistic complexity, such as coherent sentences, resulted in more significant interference compared to those with lower complexity, like sequences of syllables. The linguistic release from masking, resulting from a decrease in linguistic complexity of maskers shifting from sentences to syllables, was found to be correlated with, and also linearly additive to, the spatial release from masking due to the spatial separation of the masker and target. These findings illustrate the influence of linguistic complexity in masking speech on the recognition of target speech, suggesting the involvement of higher-level linguistic processing of irrelevant speech in noisy environment.

Differential Transcriptomic Profile of Piscirickettsia salmonis LF-89 and EM-90 During an In Vivo Spatial Separation Co-Culture in Atlantic Salmon

Salmonid rickettsial septicemia (SRS) is a critical sanitary problem in the Chilean aquaculture industry since it induces the highest mortality rate in salmonids among all infectious diseases. Piscirickettsia salmonis, a facultative intracellular bacterium, is the biological agent of SRS. In Chile, two genogroups of P. salmonis, designated as LF-89 and EM-90, have been identified. Previous studies suggested that their cohabitation triggers the expression of virulence effectors, which may be related to a higher pathogenicity in salmonids during co-infection with both P. salmonis genogroups. Therefore, we aimed to evaluate if the physical contact between two isolates from LF-89 and EM-90 is necessary to activate this effect. Through a spatially separated in vivo co-culture inside Atlantic salmon (Salmo salar) post smolts and RNA-seq analysis, we compared the differentially expressed genes (DEGs) with previous results from an in vivo mixed co-culture. The results showed that although the LF-89-like isolate and the EM-90-like isolate had a similar DEG profile under both co-culture conditions, important virulence factors observed during the mixed co-cultures (i.e., flagellar-related genes, CydD, and NCS2) were absent in the spatially separated co-cultures. Hence, the synergistic effect linked to increased pathogenicity to the host may be driven by the physical co-localization and contact between the P. salmonis LF-89-like and EM-90-like isolates.

Energy-momentum correlators of fermions at finite temperature and density

Equal-time commutators of different components of the energy-momentum tensor at spatially separated points are calculated for a relativistic quantum Fermi gas at finite temperature and density. Different definitions of such components, also known as different pseudogauges, are used and smeared with a Gaussian profile characterized by the width σ. In this way, we introduce observables that may represent measurements of energy and momentum in a spatial region of size σ. We find that the obtained commutators are sensitive to the pseudogauge chosen if the probed systems or the spatial separation are small. The pseudogauge dependence is expected as different quantum operators are analyzed in this case. On the other hand, we find that for sufficiently large probed systems or with large separation, the studied commutators are pseudogauge independent. Published by the American Physical Society 2024

Conformational Plasticity of SpyCas9 Induced by AcrIIA4 and AcrIIA2: Insights from Molecular Dynamics Simulation

CRISPR-Cas9 systems constitute bacterial adaptive immune systems that protect against phage infections. Bacteriophages encode anti-CRISPR proteins (Acrs) that mitigate the bacterial immune response. However, the structural basis for their inhibitory actions from a molecular perspective remains elusive. In this study, through microsecond atomistic molecular dynamics simulations, we demonstrated the remarkable flexibility of Streptococcus pyogenes Cas9 (SpyCas9) and its conformational adaptability during interactions with AcrIIA4 and AcrIIA2. Specifically, we demonstrated that the binding of AcrIIA4 and AcrIIA2 to SpyCas9 induces a conformational rearrangement that causes spatial separation between the nuclease and cleavage sites, thus making the endonuclease inactive. This separation disrupts the transmission of signals between the protospacer adjacent motif recognition and nuclease domains, thereby impeding the efficient processing of double-stranded DNA. The simulation also reveals that AcrIIA4 and AcrIIA2 cause different structural variations of SpyCas9. Our research illuminates the precise mechanisms underlying the suppression of SpyCas9 by AcrIIA4 and AcrIIA2, thus presenting new possibilities for controlling genome editing with higher accuracy.

Direct determination of diffusion flux in alloys via spatial separation of flux

Despite the importance of atomic diffusion in controlling high temperature deformation, it remains difficult to generally determine diffusion flux through alloys. We present thermomechanical nanomolding, where a nanomold is filled by the alloy's diffusion flux under a stress gradient, to determine the flux diffusing through an alloy's microstructure. This flux is collected in the nanomold forming nanorods. Length and composition analyses of the formed nanorods allow us to determine rate and composition of the flux, and further allow estimation of the constituents’ diffusivities in this flux. We verify this technique on metals and simple alloys, and then reveal diffusive flux in general alloys. Notably, for alloys that can access a eutectic composition in their alloy system, the flux's composition is that of the eutectic, which can be very different from the alloy's nominal composition. Moreover, the flux's overall diffusivity is greatly enhanced. This, so far unknown, eutectic mechanism is present in the majority of multicomponent alloys. These insights into diffusion flux in alloys can be used to guide the development of alloys with particularly low diffusivity or particularly high diffusivity. More generally, the presented method provides a novel toolbox to reveal the rich underlying diffusion-controlled mechanisms of deformation of alloys in general.

Effect of Different Molten Salts on Structure and Water Splitting Performance of Al-Doped Fillet Polyhedral SrTiO3.

Strontium titanium (SrTiO3) is a promising photocatalyst, but enhancing the separation, migration, and utilization of photocarriers, requires SrTiO3 with exposed anisotropic facets and minimal defect density. Here, we used NaCl and SrCl2 as fluxes to synthesize fillet polyhedral SrTiO3 particles, with Al3+ selectively adsorbed as the morphology regulator on high-energy crystal facets. Notably, Al-doped SrTiO3 synthesized in SrCl2 exhibits regular polyhedral morphology with {100}, {110}, and high-index {112} facets, showing high surface activity, low internal defect density, and superior photocatalytic performance. The excellent performance is attributed to the spatial separation of photocarriers on different crystal facets. In situ photodeposition experiments confirmed that photogenerated electrons were concentrated on the {100} facets, while holes were concentrated on the {110} and {112} facets, effectively impeding recombination. After loading RhCrOx/CoOx, Al-doped SrTiO3 synthesized in SrCl2 achieves a hydrogen evolution rate of 255µmol h-1, 64 times higher than that of Al-doped SrTiO3 synthesized in NaCl. Additionally, increasing amounts of cocatalysts further enhances the photocatalytic performance, with the average hydrogen evolution rate of SrTiO3 reaching 319µmol h⁻¹, an apparent quantum yield of 3.5% at 365nm, and a solar-to- hydrogen value of 0.181%. This discovery offers new insights into designing efficient photocatalysts for hydrogen production.

Covalent Organic Framework Encapsulating Layered Oxide Perovskite for Efficient Photosynthesis of H2O2

AbstractDriving efficient artificial photosynthesis of H2O2 is highly desirable in both academic and industrial fields. Here, a new core–shell Bi3TiNbO9@C4N heterojunction is constructed for efficient photocatalytic H2O2 production by in situ encapsulating an ultrathin layer of covalent organic framework material (C4N) on Aurivillius‐type Bi3TiNbO9 microsheets. The porous C4N layer is found to enhance visible‐light absorption ability and facilitate the adsorption and activation of the reactants and intermediates. The hybrid heterojunction follows an S‐scheme charge transfer with the assistance of a strong internal electric field (IEF), which promotes the spatial separation of photogenerated carriers effectively and maintains their strong redox abilities. As a result, the optimized Bi3TiNbO9@C4N unveils a high H2O2 yield rate of 1.25(2) mmol g−1 h−1 in the absence of sacrificial agents and cocatalyst, 10.9 and 3.5 folds higher than those of pristine Bi3TiNbO9 and C4N catalysts, respectively. This work provides an in situ encapsulating strategy to decorate covalent organic frameworks (COFs) on oxide perovskites for artificial photosynthesis of H2O2, which may stimulate the intensive investigation interests of functional materials/COFs heterojunction materials for various photocatalysis applications.

Engineered Metal–Organic Framework with Stereotactic Anchoring and Spatial Separation of Porphyrins for Amplified Ultrasound‐Mediated Pyroptosis and Cancer Immunotherapy

AbstractUltrasound‐mediated reactive oxygen species (ROS) generation is pivotal in specifically inducing pyroptosis of tumor cells. However, the effectiveness of pyroptosis is generally hindered by the constraints of ROS generation efficiency. Herein, a new porphyrin‐based metal–organic framework (Fe(TCPP)‐MOF) was rationally designed via an innovative dual‐solvent strategy to amplify ROS generation for ultrasound‐controlled pyroptosis. The crystal structure of Fe(TCPP)‐MOF was elucidated by continuous rotation electron diffraction technique, revealing its regular and rigid conformation. The porphyrin molecules were precisely oriented and firmly confined within the scaffold, effectively restricting intramolecular motion. The ample distance of 6.8 Å between two porphyrin molecules, combined with the interaction region indicator visualization, confirmed the absence of π–π stacking interactions in the Fe(TCPP)‐MOF framework, thereby avoiding the aggregation‐caused quenching effect. Furthermore, the permanent porosity and expansive surface area of Fe(TCPP)‐MOF enhanced its interaction with oxygen. These ingenious structural features endowed Fe(TCPP)‐MOF with a unique ability to generate a large amount of singlet oxygen under ultrasound activation. Meanwhile, the impetus of ultrasound also accelerated the rate of the Fenton reaction catalyzed by iron ions, significantly boosting the generation of hydroxyl radicals. Benefiting from the dual amplification of ROS, Fe(TCPP)‐MOF could efficiently induce tumor cells pyroptosis under ultrasound stimulation, thereby intensifying the potency of cancer immunotherapy.

Boosting charge transfer of BiOBr/AgBr S-scheme heterojunctions via interface Br atom co-sharing for enhanced visible-light photocatalytic activity

Efficient interfacial charge transfer and robust interfacial interactions are crucial for achieving the superior spatial separation of carriers and developing efficient heterojunction photocatalysts. Herein, BiOBr/AgBr S-scheme heterojunctions are synthesized via the co-sharing of Br atoms using an ion-exchange approach, which involves the in-situ growth of AgBr nanoparticles on the surfaces of BiOBr nanosheets. It is revealed that successful construction of a high–quality interface with strong interactions via Br atom bridge between BiOBr and AgBr, which provided a rapid migration channel for charge carriers. In addition, in-situ XPS, Kelvin probe force microscopy, and electron spin resonance evaluations confirmed the establishment of an S-scheme charge-transfer pathway in this tightly contacted heterojunction, which could efficiently prevent the recombination of photogenerated carriers while retaining carriers with a high redox capacity. Finally, the photocatalytic test confirmed that the BiOBr/AgBr heterojunction showed excellent photocatalytic performance and wide applicability thanks to the construction of high quality heterojunction. Overall, this work highlights the importance of rational design of heterogeneous interfaces at the atomic level in photocatalysis, and contributes to rationally design BiOBr-based S-scheme heterojunctions photocatalytic materials with high quality atomic co-sharing interfaces.

Femtosecond laser ablation of nitrocellulose for spatio-temporal flow control in µPADs

Microfluidic paper-based analytical devices (μPADs) are gaining popularity due to their low cost and ease of use, but controlling fluid flow for more complex biochemical assays within these devices remains challenging. This study investigates femtosecond laser ablation of nitrocellulose (NC), a preferred material for µPADs, to create mechanically switchable barriers and flow controllers. We investigated NC ablation using single laser pulses and spatially overlapping pulses that generate lines. Single pulse ablation thresholds were determined for wavelengths of 1,030 nm, 515 nm and 343 nm. Line ablation characteristics were investigated as a function of the temporal and spatial pulse separation and laser wavelength. High aspect ratio grooves (up to 4.26) were achieved under specific conditions. These grooves can be used to define the spatial separation of the flow in separated microchannels or to form a barrier line perpendicular to the microchannel that can modulate the temporal behavior of the fluid flow. This barrier introduced an additional high flow resistance slowing down the flow or, if it was designed to cut through nitrocellulose at the entire depth, completely stopped the liquid flow. It was further shown that a barrier formed in this way could be switched by mechanically bending the µPAD at the barrier position. The femtosecond laser patterning method presented here provides precise spatio-temporal control not only for flow branching and multiplexing, but also for controlling flow speed and switching flow on and off within the same manufacturing process. Our results open up new possibilities for complex, multi-step assays on µPADs.

Combined metabolic engineering and lipid droplets degradation to increase vitamin A production in Saccharomyces cerevisiae

BackgroundIn microbial cell factories, substrate accessibility to enzyme is a key factor affecting the biosynthesis of natural products. As a robust chassis cells for biofuels and bioproducts, Saccharomyces cerevisiae also encounters the challenge since different enzymes and precursors are typically compartmentalized in different organelles. Such spatial separation could largely limit the efficiency of enzymatic reactions. In this study, the production of the hydrophobic product (vitamin A) was highly improved by metabolic engineering combined with degrading lipid droplets (the primary organelle storing β-carotene) to achieve efficient contact between β-carotene and 15, 15’-β-carotene monooxygenases in Saccharomyces cerevisiae.ResultsTo efficiently produce vitamin A in Saccharomyces cerevisiae, ten 15, 15’-β-carotene monooxygenases (BCMOs) were firstly evaluated. The strain carrying marine bacterium 66A03 (Mb. BCMO) achieved the highest vitamin A titer. Co-adding 10% dodecane and 1% dibutylhydroxytoluene increased vitamin A titer to 19.03 mg/L in two-phase fermentation. Since most β-carotene is stored in LDs while BCMO is located in the cytosol, we developed a strategy to release β-carotene from LDs to better contact with BCMO. By overexpressing TGL3 and TGL4 using an ion-responsive promoter after high accumulation of β-carotene in LDs, LDs were sequentially degraded, which dramatically improved vitamin A production. Finally, by overexpressing tHMG1, ERG20, and CrtI and introducing Vitreoscilla hemoglobin, vitamin A titer reached 219.27 mg/L, which was a 10.52-folds increase over the original strain in shake flasks, and finally reached 1100.83 mg/L in fed-batch fermentation. The effectiveness of LDs degradation on promoting the formation of β-carotene cleaved product has also been verified in β-ionone synthesis with 44.07% increased yield.ConclusionsOverall, our results highlighted the significance of sequential degrading LDs on vitamin A overproduction in recombinant yeast, and verified that combining metabolic and LDs engineering is an efficient strategy to improve vitamin A production. This integrated strategy can be applied to the overproduction of other hydrophobic compounds with similar characteristics.

Perinuclear compartment controls calcineurin/MEF2 signaling for axonal outgrowth of hippocampal neurons

Central to the process of axon elongation is the concept of compartmentalized signaling, which involves the A-kinase anchoring protein (AKAP)-dependent organization of signaling pathways within distinct subcellular domains. This spatial organization is also critical for translating electrical activity into biochemical events. Despite intensive research, the detailed mechanisms by which the spatial separation of signaling pathways governs axonal outgrowth and pathfinding remain unresolved. In this study, we demonstrate that mAKAPα (AKAP6), located in the perinuclear space of primary hippocampal neurons, scaffolds calcineurin, NFAT, and MEF2 transcription factors for activity-dependent axon elongation. By employing anchoring disruptors, we show that the mAKAPα/calcineurin/MEF2 signaling pathway, but not NFAT, drives the process of axonal outgrowth. Furthermore, mAKAPα-controlled axonal elongation is linked to the changes in the expression of genes involved in Ca2+/cAMP signaling. These findings reveal a novel regulatory mechanism of axon growth that could be targeted therapeutically for neuroprotection and regeneration.

Facet-dependent spatial separation of dual cocatalysts on MOF photocatalysts for H2O2 production coupling biomass oxidation with enhanced performance

Cooperative coupling of photocatalytic two-electron oxygen reduction reaction (2e-ORR) with oxidative organic synthesis holds great promise for sustainable production of valuable chemicals. To achieve high performance, the rational design of photocatalysts with effective electron-hole separation and redox capability is crucial. Herein, a MOF-based photocatalyst with crystal facet-dependent spatial separation of dual cocatalysts is constructed for photocatalytic 2e-ORR coupled with vanillyl alcohol oxidation reaction (VAOR). The facet-dependent growth of reductive Pd and oxidative CoOx cocatalysts respectively on the {100} and {001} facets of MIL-125-NH2 enables the directional migration of photogenerated carries, facilitating the charge separation for redox reactions. Additionally, the interaction between Pd and MIL-125-NH2 modulates the Pd sites into electron-sufficient state with upshifted d-band center, promoting the O2 activation and *OOH intermediate formation. The rationally designed composite photocatalyst delivers an excellent H2O2 yield of 74.8 mM g−1 h−1 and a high vanillic acid production rate of 80.9 mM h−1 g−1 with the conversion and selectivity of 96.8 % and 91.1 %, respectively.

Enhanced photocatalytic performance of SnS2/ZnO Z-scheme composite photocatalysts for efficient environmental remediation

Photocatalysts based on zinc oxide (ZnO) are promising for environmental applications, but their weak photoresponse and low photocarrier separation efficiency limit their practical use. To tackle this issue, we constructed Z-scheme composite photocatalysts of ZnO to boost its photocatalytic performance. We achieved the Z-scheme structure by hydrothermal modification of SnS2 nanoparticles onto ZnO microspheres. Its photocatalytic performance was evaluated through the degradation of Rhodamine B (RhB) under visible light with the assistance of magnetic stirring. The composite photocatalyst exhibited superior performance compared to individual ZnO and SnS2, achieving an optimal degradation rate of 0.0706 min⁻¹. This rate was 15.08 times higher than that of individual ZnO and 10.51 times higher than individual SnS2. Free radical trapping experiments showed that ·O2⁻ and ·OH radicals played a key role in RhB degradation. The Z-scheme composite structure established novel charge transport pathways, guided the migration of photogenerated carriers, and improved spatial separation, thereby enhancing photocatalytic performance. This study provides valuable insights into the design of highly efficient photocatalysts for environmental remediation, offering a promising solution for addressing challenges in pollution control and wastewater treatment.

Regulating electrons transfer through Pd-O-Bi bridges for boosting photocatalytic CO2 reduction

The photocatalytic efficiency of bismuth-based metal-organic framework (Bi-MOF) is extremely restricted by the rapid recombination of photogenerated electron-hole pairs, which reduce the number of electrons involved in the photocatalytic reduction reaction. Constructing precise interfacial bond bridges between metal nanoparticles (NPs) and MOFs has emerged as an effective strategy to address the above-mentioned issues, promoting the electrons transfer. Herein, this study improves the sluggish dynamics of photogenerated charge in Bi-MOF by inducing the Pd-O-Bi bond bridges at the interface on a Pd NPs-decorated Bi-MOF (Pd/Bi-MOF) nanosheets. This phenomenon results in an interaction between Pd NPs and the Bi-MOF support. And Pd-O-Bi bond bridges provide the fast electron transfer channels, triggering the directional migration of photogenerated electrons from Pd to Bi node, then enhancing the spatial separation of photogenerated electron-hole pairs, finally facilitating overall photocatalytic CO2 reduction. The presence of these bond bridges leads to higher enhancement in CO production for Pd/Bi-MOF nanosheets compared to the Bi-MOF nanosheets under visible light irradiation after 4.5 h. This research demonstrates the importance of interfacial bond bridges and provides a reasonable guide to design efficient photocatalyst for reduction of CO2 to CO.

Engineered Metal-Organic Framework with Stereotactic Anchoring and Spatial Separation of Porphyrins for Amplified Ultrasound-Mediated Pyroptosis and Cancer Immunotherapy.

Ultrasound-mediated reactive oxygen species (ROS) generation is pivotal in specifically inducing pyroptosis of tumor cells. However, the effectiveness of pyroptosis is generally hindered by the constraints of ROS generation efficiency. Herein, a new porphyrin-based metal-organic framework (Fe(TCPP)-MOF) was rationally designed via an innovative dual-solvent strategy to amplify ROS generation for ultrasound-controlled pyroptosis. The crystal structure of Fe(TCPP)-MOF was elucidated by continuous rotation electron diffraction technique, revealing its regular and rigid conformation. The porphyrin molecules were precisely oriented and firmly confined within the scaffold, effectively restricting intramolecular motion. The ample distance of 6.8 Å between two porphyrin molecules confirmed the absence of π-π stacking interactions in the Fe(TCPP)-MOF framework, thereby avoiding the aggregation-caused quenching effect. Furthermore, the permanent porosity and expansive surface area of Fe(TCPP)-MOF enhanced its interaction with oxygen. These ingenious structural features endowed Fe(TCPP)-MOF with a unique ability to generate a large amount of singlet oxygen under ultrasound activation. Meanwhile, the impetus of ultrasound also accelerated the rate of the Fenton reaction catalyzed by iron ions, significantly boosting the generation of hydroxyl radicals. Benefiting from the dual amplification of ROS, Fe(TCPP)-MOF could efficiently induce tumor cells pyroptosis under ultrasound stimulation, thereby intensifying the potency of cancer immunotherapy.

Fabrication of recoverable Bi2O2S/Bi5O7I/ZA hydrogel beads for enhanced photocatalytic Hg0 removal in the presence of H2O2

The effective removal of elemental mercury (Hg0) is a global challenge due to its toxicity and bioaccumulation threat to public health and ecosystems. Photocatalytic technology by visible light-driven photocatalysts is promising for Hg0 removal. However, effective separation of photocatalyst powders from reaction solution limits its widespread use. To solve the problem, we report for the first time the successful fabrication of recoverable Bi2O2S/Bi5O7I/ZA hydrogel beads for enhanced photocatalytic Hg0 removal in the presence of H2O2. Characterization techniques such as XRD, TEM, EDS, XPS, UV–vis DRS, PL, etc. are employed to understand the physicochemical properties and photoelectric performance of the photocatalysts. The serial BOSI photocatalysts all outperform the single component, which is attributed to the formation of a heterojunction between Bi5O7I and Bi2O2S. The coupling of 2-BOSI-ZA beads with H2O2 shows favorable synergistic effect, with Hg0 removal efficiency in the following order: H2O2 + 2-BOSI-ZA < 2-BOSI-ZA + FSL < H2O2 + 2-BOSI-ZA + FSL. TPC, EIS, and PL tests confirm that the introduction of Bi2O2S effectively suppresses charge carrier recombination. ESR and free radicals capture experiments demonstrate that the main species responsible for removal of Hg0 are •O2– and •OH. Density functional theory calculations exhibit that the internal electric field (IEF) between Bi5O7I and Bi2O2S contributes to the spatial charge separation of the heterojunction. The IEF leads to an S-scheme carrier transfer mechanism at the Bi2O2S/Bi5O7I interface that benefits the carrier separation on Bi5O7I, resulting in an enhanced photocatalytic performance. This work can provide further inspiration for designing hydrogel photocatalysts with an excellent activity in conjunction with oxidants in the field of mercury pollution control.

Research on Decoration of Tourist Homestays and Hotels Based on Digital Image Network Computing

In today’s digital age, the tourism and homestay industry is facing unprecedented opportunities and challenges. With the continuous expansion of the tourism market, tourists’ demands for accommodation experience are becoming increasingly diverse and personalized. Traditional design methods often struggle to quickly respond to these changes, fully showcase regional characteristics, and achieve efficient personalized customization. At the same time, how to integrate modern technology while retaining traditional charm to enhance the attractiveness and comfort of homestays has become an urgent problem to be solved. This paper aims to explore in depth how to use this technological framework to optimize the decoration design of tourist homestays, in order to create living spaces that retain traditional charm and are rich in modern technology. By utilizing digital image network computing technology, it is possible to conduct 3D modeling and virtual simulation of the indoor space of homestays. By simulating different furniture placement and spatial separation schemes, combined with tourist behavior analysis data, the optimal spatial layout scheme is automatically recommended to achieve maximum space utilization and a comfortable living experience. This technology can analyze a large number of color matching cases, combined with the cultural characteristics of the area where the homestay is located, and apply the principles of color psychology to provide personalized color schemes for homestay design. Meanwhile, through style recognition and recommendation algorithms, designers can quickly locate and integrate traditional and modern elements to create unique decorative styles.

Investigation of inter-dot tunnelling effect in hybrid coupled QDs heterostructures for short-wave infrared detection (SWIR) application

This paper explores the coupling between two different types of dots for enhancing the performance of p type/hole based (p-i-p) quantum dot infrared photodetectors (QDIPs). There are two possible con: Stranski-Krastanov (SK) QDs can be deposited on submonolayer (SML) QDs, or the SML QDs can be deposited first, followed by SK QDs. Here, both configurations are tried, and the fact that the tunnelling improves with a decrease in the barrier is exploited. The tunnelling of carriers from one QD to another QD is facilitated by the overlap of their wavefunctions, which depends on their spatial separations between the dots. A smaller barrier will lead to enhanced tunnelling probability. Utilising this idea, samples with 20 nm and 7.5 nm barriers between the QDs are grown with both types of configurations. An enhancement is anticipated in the absorption and carrier lifetime of the p-i-p QDIP structures, making them well-suited for detection in short-wavelength infra-red regions. The p-i-p configuration with the active layers of coupled QDs sandwiched between p-type dopped layers, can effectively absorb SWIR photons and generate long-lived carriers for improved photodetection performance. With the help of Photoluminescence (PL), Photoluminescence Excitation (PLE), and X-ray Diffraction (XRD) experiments, we expect large dispersion in SK on SML configuration, significantly improved carrier transfer via tunnelling and thermalisation and, changes in dot density for both of the configurations. Development of a more efficient SWIR device is expected by the insightful understanding of carrier transfer by tunnelling and thermalization with respect to the barrier thickness in the coupled QD based heterostructures.

Engineering defect-rich H-W18O49 nanowire/MIL-125(Ti) nanosheet S-scheme heterostructure for remarkable CO2 photoconversion

The rational construction of heterojunctions with surface defects and localized surface plasmon resonance (LSPR) effect is a promising strategy for improving CO2 photoreduction performance. Herein, the one-dimensional/two-dimensional (1D/2D) S-scheme heterostructures integrated with non-stoichiometric 1D W18O49 nanowires (H-W18O49 NWs) and 2D ultrathin MIL-125(Ti) nanosheets (MIL-125(Ti) NSs) were constructed by self-assembly for photocatalytic CO2 reduction. In situ X-ray photoelectron spectroscopy (XPS), electron spin resonance spectra (ESR), and photoluminescence (PL) spectroscopy characterizations confirm the construction of S-scheme heterojunction and the solid internal electric field at the heterointerface enables effective spatial charge separation while keeping a strong redox capability. The hot electrons generated from the LSPR effect of visible-near-infrared light-excited H-W18O49 NWs can be injected into MIL-125(Ti) NSs to increase the electron density and accelerate the reaction rate. Thus, the optimized H-W18O49 NW/MIL-125(Ti) NS heterostructure exhibited good performance, achieving a CO yield of 202.37 μmol g-1h−1. This study enriches the diversity and architecture of available heterostructures for photocatalytic applications.