-
Nano-micro Letters May 2024Perovskite solar cells (PSCs) offer low costs and high power conversion efficiency. However, the lack of long-term stability, primarily stemming from the interfacial... (Review)
Review
Perovskite solar cells (PSCs) offer low costs and high power conversion efficiency. However, the lack of long-term stability, primarily stemming from the interfacial defects and the susceptible metal electrodes, hinders their practical application. In the past few years, two-dimensional (2D) materials (e.g., graphene and its derivatives, transitional metal dichalcogenides, MXenes, and black phosphorus) have been identified as a promising solution to solving these problems because of their dangling bond-free surfaces, layer-dependent electronic band structures, tunable functional groups, and inherent compactness. Here, recent progress of 2D material toward efficient and stable PSCs is summarized, including its role as both interface materials and electrodes. We discuss their beneficial effects on perovskite growth, energy level alignment, defect passivation, as well as blocking external stimulus. In particular, the unique properties of 2D materials to form van der Waals heterojunction at the bottom interface are emphasized. Finally, perspectives on the further development of PSCs using 2D materials are provided, such as designing high-quality van der Waals heterojunction, enhancing the uniformity and coverage of 2D nanosheets, and developing new 2D materials-based electrodes.
PubMed: 38782775
DOI: 10.1007/s40820-024-01417-1 -
Cureus Dec 2023Background Periodontal regeneration aims for the three-dimensional reconstruction of bone defects, and over the years, bone grafts with or without barrier membranes have...
Background Periodontal regeneration aims for the three-dimensional reconstruction of bone defects, and over the years, bone grafts with or without barrier membranes have provided us with promising results. Particulate bone grafts can be classified according to the source of procurement as autografts, allografts, xenografts, and alloplasts. Bioglass, an innovative alloplast that uses silica particles as a matrix incorporated with calcium and phosphorus, has been extensively used as a propitious material for bone regeneration owing to its inherent osteogenic ability and biocompatibility but presents with various disadvantages such as slow degradation rate, low mechanical strength, and fracture resistance. A novel silver (Ag)-gadolinium (Gd)-doped bioglass was fabricated to improve the mechanical properties, biocompatibility, and osteogenic ability when compared with bioglass (control). Materials and methods The Ag- and Gd-doped bioglass network was prepared and assessed for the morphological and structural properties by scanning electron microscopy (SEM) analysis, X-ray diffraction (XRD), and attenuated total reflectance (ATR)-infrared (IR). The cytotoxicity of Gd and Ag-doped bioglass was assessed using the MG63 cell line through the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide) assay at various concentrations and the absorbance of the solution was measured at 570 nm using a microplate reader. The osteogenic ability of the material was assessed by alkaline phosphatase activity and collagen estimation. Results ATR-IR spectroscopy, SEM, and XRD were used to examine the bioglass network doped with Gd and Ag. ATR-IR exhibited classic silicate bands, whereas SEM indicated particles bigger than 5 μm. XRD analysis revealed the production of Na2Ca2Si3O9, Na2Ca4(PO4)2SiO4, and wollastonite. The excellent crystallinity of Na2Ca2Si3O9 provided the bioglass network with good mechanical characteristics. The Gd-Ag-bioglass did not exhibit any toxicity towards the living cells at increasing concentrations from 12.5 µg to 100 µg. The alkaline phosphatase activity was increased by 10% and the collagen estimation remained consistent with bioglass (control). Conclusion In conclusion, the fabrication of the novel Gd-Ag-doped bioglass shows good cytocompatibility and osteogenic ability and shows great potential to enhance bone regeneration.
PubMed: 38274939
DOI: 10.7759/cureus.51086 -
Nanomaterials (Basel, Switzerland) Jul 2023Transparent conductors (TC) have been widely applied in a wide range of optoelectronic devices. Nevertheless, different transparent spectral bands are always needed for...
Transparent conductors (TC) have been widely applied in a wide range of optoelectronic devices. Nevertheless, different transparent spectral bands are always needed for particular applications. In this work, indium tin oxide (ITO)-free TCs with tunable transparent bands based on the film structure of TiO/Ag/AZO (Al-doped ZnO) were designed by the transfer matrix method and deposited by magnetron sputtering. The transparent spectra and figure-of-merit (FOM) were effectively adjusted by precisely controlling the Ag layer's thickness. The fabricated as-deposited samples exhibited an average optical transmittance larger than 88.3% (400-700 nm), a sheet resistance lower than 7.7 Ω.sq, a low surface roughness of about 1.4 nm, and mechanical stability upon 1000 bending cycles. Moreover, the samples were able to hold optical and electrical properties after annealing at 300 °C for 60 min, but failed at 400 °C even for 30 min.
PubMed: 37513119
DOI: 10.3390/nano13142108 -
The Journal of Physical Chemistry. A Oct 2023The thermal decomposition of 2- and 4-iodobenzyl iodide at high temperatures was investigated by mass-selective threshold photoelectron spectroscopy (ms-TPES) in the gas...
Thermal Decomposition of 2- and 4-Iodobenzyl Iodide Yields Fulvenallene and Ethynylcyclopentadienes: A Joint Threshold Photoelectron and Matrix Isolation Spectroscopic Study.
The thermal decomposition of 2- and 4-iodobenzyl iodide at high temperatures was investigated by mass-selective threshold photoelectron spectroscopy (ms-TPES) in the gas phase, as well as by matrix isolation infrared spectroscopy in cryogenic matrices. Scission of the benzylic C-I bond in the precursors at 850 K affords 2- and 4-iodobenzyl radicals (- and -ICHCH), respectively, in high yields. The adiabatic ionization energies of -ICHCH to the X̃(A') and ã(A') cation states were determined to be 7.31 ± 0.01 and 8.78 ± 0.01 eV, whereas those of -ICHCH were measured to be 7.17 ± 0.01 eV for X̃(A) and 8.98 ± 0.01 eV for ã(A). Vibrational frequencies of the ring breathing mode were measured to be 560 ± 80 and 240 ± 80 cm for the X̃(A') and ã(A') cation states of -ICHCH, respectively. At higher temperatures, subsequent aryl C-I cleavage takes place to form α,2- and α,4-didehydrotoluene diradicals, which rapidly undergo ring contraction to a stable product, fulvenallene. Nevertheless, the most intense vibrational bands of the elusive α,2- and α,4-didehydrotoluene diradicals were observed in the Ar matrices. In addition, high-energy and astrochemically relevant CH isomers 1-, 2-, and 5-ethynylcyclopentadiene are observed at even higher pyrolysis temperatures along with fulvenallene. Complementary quantum chemical computations on the CH potential energy surface predict a feasible reaction cascade at high temperatures from the diradicals to fulvenallene, supporting the experimental observations in both the gas phase and cryogenic matrices.
PubMed: 37734109
DOI: 10.1021/acs.jpca.3c04688 -
JPMA. the Journal of the Pakistan... Feb 2024To evaluate composite class II restoration proximal contacts and contours by comparing saddlecontoured metal matrix and pre-contoured self-adhesive matrix system. (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To evaluate composite class II restoration proximal contacts and contours by comparing saddlecontoured metal matrix and pre-contoured self-adhesive matrix system.
METHODS
The randomised controlled trial (NCT05414656) was conducted at the Department of Operative Dentistry, School of Dentistry, Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad, Pakistan, from May to October 2022, and comprised of patients having supra-gingival class II cavities. They were randomised into class II restoration with saddle-contoured matrix band group A, and restoration with pre-contoured self-adhesive matrix group B. The tightness of proximal contacts was evaluated using the Fédération Dentaire Internationale criteria and the quality of proximal contours was assessed using clinical and radiographic examination. Data was analysed using SPSS 16.
RESULTS
Of the 60 subjects, 42(70%) were females and 18(30%) were males. The overall mean age was 38.03±15.33 years. There were 30(50%) subjects in each of the 2 groups. The highest restoration was needed in the upper premolar 20(33.3%). The tightness of proximal contact was not significantly different between the groups (p=0.94). Clinical examination for production of good contours was higher in group A compared to group B, but the difference was not significant (p>0.05).
CONCLUSIONS
There was no significant difference between saddle-contoured metal matrix and pre-contoured selfadhesive matrix for composite class II restoration proximal contacts and contours.
CLINICAL TRIAL LINK
https://clinicaltrials.gov RCT (NCT05414656).
Topics: Male; Female; Humans; Young Adult; Adult; Middle Aged; Composite Resins; Resin Cements; Matrix Bands; Research Design; Bicuspid; Dental Restoration, Permanent
PubMed: 38419215
DOI: 10.47391/JPMA.8627 -
Nanomaterials (Basel, Switzerland) Dec 2023This study focuses on the fabrication of polymer nanocomposite films using polyvinyl alcohol (PVA)/graphene quantum dots (GQDs). We investigate the relationship between...
This study focuses on the fabrication of polymer nanocomposite films using polyvinyl alcohol (PVA)/graphene quantum dots (GQDs). We investigate the relationship between the structural, thermal, and nanoscale morphological properties of these films and their photoluminescent response. Although according to X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and differential thermal analysis (DTA), the incorporation of GQDs does not significantly affect the percentage crystallinity of the PVA matrix, for a range of added GQD concentrations, atomic force microscopy (AFM) showed the formation of islands with apparent crystalline morphology on the surface of the PVA/GQD films. This observation suggests that GQDs presumably act as nucleating agents for island growth. The incorporation of GQDs also led to the formation of characteristic surface pores with increased stiffness and frictional contrast, as indicated by ultrasonic force microscopy (UFM) and frictional force microscopy (FFM) data. The photoluminescence (PL) spectra of the films were found to depend both on the amount of GQDs incorporated and on the film morphology. For GQD loads >1.2%wt, a GQD-related band was observed at ~1650 cm in FT-IR, along with an increase in the PL band at lower energy. For a load of ~2%wt GQDs, the surface morphology was characterized by extended cluster aggregates with lower stiffness and friction than the surrounding matrix, and the PL signal decreased.
PubMed: 38202460
DOI: 10.3390/nano14010005 -
Scientific Reports Aug 2023Lieb lattice is one of the simplest bipartite lattices, where compact localized states (CLS) are observed. This type of localization is induced by the peculiar topology...
Lieb lattice is one of the simplest bipartite lattices, where compact localized states (CLS) are observed. This type of localization is induced by the peculiar topology of the unit cell, where the modes are localized only on selected sublattices due to the destructive interference of partial waves. We demonstrate the possibility of magnonic Lieb lattice realization, where flat bands and CLS can be observed in the planar structure of sub-micron in-plane sizes. Using forward volume configuration, the Ga-doped YIG layer with cylindrical inclusions (without Ga content) arranged in a Lieb lattice with 250 nm period was investigated numerically (finite-element method). The structure was tailored to observe, for a lowest magnonic bands, the oscillatory and evanescent spin waves in inclusions and matrix, respectively. Such a design reproduces the Lieb lattice of nodes (inclusions) coupled to each other by the matrix with the CLS in flat bands.
PubMed: 37542063
DOI: 10.1038/s41598-023-39816-w -
Optics Express Mar 2024In this paper, we investigate the properties of temporally-topological defect modes (TTDMs) (or temporally-topological interface states) in the topological photonic time...
In this paper, we investigate the properties of temporally-topological defect modes (TTDMs) (or temporally-topological interface states) in the topological photonic time crystal (PTC) systems. The PTC systems are constructed by the cascade of multiple sub-PTCs that possess temporal inversion symmetries and different topologies. The cases of two-, three-, and multiple-sub-PTC for the topological PTC system are studied. By transfer matrix method, we find that the TTDMs appear when the topological signs of the corresponding gaps in the sub-PTCs are different. The positions of TTDMs can be adjusted by changing the modulation strength of the refractive index, the time duration, and the period of the sub-PTCs. Moreover, the number of TTDMs is one less than the number of sub-PTCs. In addition, the robustness of the systems is also studied. We find that the topological PTC systems have good robustness, especially on the random configuration of the refractive index and time duration for the temporal slabs in the systems. Such research may provide a new degree of freedom for PTC applications, such as novel PTC lasers, tunable band-stop or band-suppression PTC filters, and many others, in the field of integrated photonic circuits for optical communications.
PubMed: 38571207
DOI: 10.1364/OE.517616 -
Advanced Science (Weinheim,... Dec 2023The multispectral compatible infrared camouflage technology is implemented these days to counter the developing infrared detectors and detectors of other bands. However,...
The multispectral compatible infrared camouflage technology is implemented these days to counter the developing infrared detectors and detectors of other bands. However, the conflict between delicate optical structures and scalable procedures has significantly impeded the development and application of multispectral-compatible camouflage technology. Therefore, a semi-open Fabry-Perot structure is introduced, and the color and infrared emissivity by structural parameters for color-matched visible-infrared compatible camouflage are modulated. The prepared compatible camouflage film exhibits visible camouflage by the minimum color difference of 1.6 L*a*b* (under desert background) and infrared camouflage by low emission (ε ≈ 0.17 and ε ≈ 0.143). Due to its flexibility and scalability, the compatible camouflage film can be applied in practical applications and exhibits desirable visible and infrared camouflage performance in different battlefield backgrounds.
PubMed: 37888858
DOI: 10.1002/advs.202303452 -
BMC Oral Health Aug 2023Poor contact tightness and contour in class II composite restorations are significant problems in clinical practice. They affect occlusal stability and periodontal...
BACKGROUND
Poor contact tightness and contour in class II composite restorations are significant problems in clinical practice. They affect occlusal stability and periodontal health. The aim of this study was to evaluate proximal contact tightness and contour established after completing class II direct composite restorations using two pre-contoured matrix systems.
METHODS
Standardized mesio-occlusal cavities were prepared in twenty typodont lower right first permanent molar teeth. Prepared teeth were randomly divided into two groups according to matrix system: Group 1, Sectional matrix system with a separation ring (Palodent V3); and Group 2, Circumferential matrix system with integrated tightener (Palodent 360). Contact tightness was evaluated using universal testing machine. Area, depth and curvature radius of proximal surface concavity in the restoration were evaluated using contact stylus profilometer. T-test was used for comparison between groups.
RESULTS
Sectional matrix showed higher contact tightness than circumferential matrix system. The results of proximal surface concavity in the restoration showed significantly higher area and depth of concavity with lower radius of curvature in circumferential matrix compared to sectional matrix.
CONCLUSIONS
The use of separation ring with sectional matrix provides superior contact tightness compared to circumferential matrix. However, both matrix systems presented some deficiency regarding proximal contour of direct class II resin composite restoration.
Topics: Humans; Dental Restoration, Permanent; Dental Cavity Preparation; Matrix Bands; Composite Resins; Molar
PubMed: 37533048
DOI: 10.1186/s12903-023-03222-5