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The formation of a complex fracture network with sufficient proppant conductivity is crucial for the efficient development of deep shale gas. Due to cost considerations, quartz sand has commonly replaced ceramic proppant in the field. However, the significant crushing of quartz sand and its distribution as multiple particle sizes both before and after crushing, termed as particle size redistribution, raises concerns about its ability to meet the demands of the fracture network. Based on contact mechanics, we developed an evolutionary equation for fracture width that considers particle size redistribution. The particle crushing is described using a fragmentation replacement method, and changes in specific surface area before and after crushing are used to correct the permeability model of the fracture. By integrating models of fracture width and permeability evolution, we have established an analytical model for proppant conductivity that accounts for quartz sand crushing and its particle size redistribution. Numerical simulations further validate the predictive accuracy of our model. Sensitivity analyses investigate the impact of quartz sand degree of crushing, compressive strength, particle size, particle combination ratio, and closure pressure on fracture conductivity, demonstrating the reliability of quartz sand as a substitute for ceramic proppant in deep shale applications. HIGHLIGHTS: Developed a new model for fracture conductivity considering the embedding and crushing of multiple particle sizes of quartz sand in a proppant monolayer. Demonstrated the reliability of replacing ceramic proppants with quartz sand in deep oilfield applications through model studies. Provided an alternative evaluation method for selecting and optimising sand addition during construction based on reservoir conditions. [ABSTRACT FROM AUTHOR]

At elevated temperatures, the prototypical organic solvents used to study the self‐assembly of supramolecular monolayers at liquid–solid interfaces alter a graphite substrate by intercalation. As a consequence, less strongly bound supramolecular monolayers become thermodynamically unstable, as probed by scanning tunneling microscopy. Complementary characterization by atomic force microscopy, confocal Raman spectroscopy and low energy electron microscopy consistently points to subsurface changes in the top few layers of the graphite substrate due to solvent intercalation. High‐temperature annealing at 900 °C in the vacuum restores the adsorption properties of the graphite substrates, indicating a high activation energy for deintercalation. However, strongly adsorbing hydrogen‐bonded monolayers of trimesic acid inhibit solvent intercalation and thus protect the graphite substrate. Mildly solvent‐intercalated graphite may prove useful as an easily prepared graphitic material with further weakened adsorption properties. [ABSTRACT FROM AUTHOR]

Many artificial molecular machines have been synthesized, and various functions have been expressed by changing their molecular conformations. However, their structures are still simple compared with those of biomolecular machines, and more energy is required to control them. To design artificial molecular machines with more complex structures and higher functionality, it is necessary to combine molecular machines with simple movements such as components. This means that the motion of individual molecular machines must be precisely controlled and observed in various environments. At the air – water interface, the molecular orientation and conformation can be controlled with little energy as thermal fluctuations. We designed various molecular machines and controlled them using mechanical stimuli at the air – water interface. We also controlled the transfer of forces to the molecular machines in various lipid matrices. In this review, we describe molecular pliers with amphiphilic binaphthyl, molecular paddles with binuclear platinum complexes, and molecular rotors with julolidine and BODIPY that exhibit twisted intramolecular charge transfer. IMPACT STATEMENT: This review discusses the dependence of the behaviour of molecular machines around their environment through the mechanically control of simple molecular machines at the air – water interface. [ABSTRACT FROM AUTHOR]

In this research, we have studied a self-heating effect in hybrid 2D-3D heterostructure diode, considering planar GaN-based structure of 1280 nm with n-type channel and donor concentration of 6·1017 cm-3. Two type c-plane substrate-based sapphire and GaN are considered in order to investigate heating effects in diode channel. Monolayer hexagonal boron nitride (h-BN) on the top of canal is considered as an element for thermal control of the diode. The model of a heating based on macroscopic thermal parameters of materials is used. The simulation of diode operation was carried out using the Ensemble Monte Carlo Technique selfconsistently with numerical solving of system of heat equations by full multigrid (FMG) method. Transport properties of diode is considered under condition of high electric fields and impact ionization. Characteristics of the diode with both h-BN monolayer and without one were obtained at DC applied voltage. A temperature distribution in diode is obtained with account of thermal boundary resistance at each interface, considering voltage range of 0-20 V. In strong electric field in anode, the heating rises maximal temperature in channel diode up to over 600 K. The h-BN was found to affect the temperature magnitudes and their redistribution in diode channel. Temperature decrease can achieve 3 % and increase in case of high temperature region. Role h-BN monolayer as a factor avoiding formation of localized overheating of a device is demonstrated. It is shown that, h-BN monolayer is effective in diode using the substrate with low thermal conductivity and can be applied for semiconductor devices with length of several micrometers. [ABSTRACT FROM AUTHOR]

The drying and storage process in jelly candy present a significant challenges due to their impact on stability. This study investigates the drying kinetics and moisture sorption isotherms of jelly candy. The aim of the study focuses on comparing the effectiveness of conventional models (Courie-GAB-Peleg) and artificial neural networks (ANN) in analyzing the sorption behaviour of jelly candy, specifically when corn stract was added. In addition, the drying characteristics, shrinkage, and storage recommendations of jelly candies were also identified. The static gravimetric method uses a saturated solution of sulfuric acid with 13 (thirteen) different concentrations to condition the water activity (aw) in the range of 0.06–0.89 (25–35 °C). In addition, the oven drying processed at a temperature of 40–60 °C with an air speed of 3.6 m/s. The study results show that the final equilibrium moisture content (EMC) of drying has a range of 19.74%w.b-22.02%w.b, and the highest drying rate is 0.11%w.b/min-0.27%w.b/min. At the end of dryng, shrinkage of jelly candy is 22-33% compared to initial conditions. Based on the model accuracy test, it shows that the Peleg model was identified as the best model. The correlation between drying kinetic and moisture sorption was explained with storage recommendations and its recommendation for good jelly candy storage is 24.19%w.b. These storage recommendations were used to determine the appropriate stop of the drying process to minimize drying time. [ABSTRACT FROM AUTHOR]

Introduction: Periodontitis, affecting approximately 3.9 billion individuals globally, significantly impacts quality of life and has raised interest in its potential systemic effects. Sodium perborate, a common component in oral care products for biofilm control, is widely used, though concerns about its safety persist. This study aimed to evaluate the in vitro toxicity of six commercial oral care products and varying concentrations of sodium perborate, utilizing human gingival fibroblasts (HGF) and keratinocytes (HaCat) as cell models. Methods: Experiments were performed in both 2D monolayer and 3D cultures using MTT and electrical impedance assays, adhering to the manufacturer's recommended exposure time of 30–60 s for product testing. For the reconstructed epidermis model, a prolonged exposure time of 42 min was applied, following the Organization for Economic Cooperation and Development (OECD) Test Guideline 439. Results: Results indicated that all products and sodium perborate at 1 mg/mL were cytotoxic in monolayer cultures. However, at concentrations relevant to commercial formulations (0.06 mg/mL sodium perborate), no significant toxicity was observed. In contrast, the 3D culture models, including spheroids and reconstructed epidermis, exhibited minimal to no cytotoxic effects for the commercial products, with sodium perborate showing no significant toxicity below 0.1 mg/mL. The reconstructed epidermis model, used as surrogate for oral mucosa, further confirmed that the products were non-irritating, in compliance with OECD TG 439 standards. Discussion: This study highlights the importance of considering exposure time, dosage, and cellular model when assessing the safety of oral care products. While 2D models are useful for preliminary screenings, 3D models provide a more physiologically relevant assessment, emphasizing the need for robust testing protocols to ensure product safety. [ABSTRACT FROM AUTHOR]

Hole‐collecting monolayers have greatly advanced the development of positive‐intrinsic‐negative perovskite solar cells (p‐i‐n PSCs). To date, however, most of the anchoring groups in the reported monolayer materials are designed to bind to the transparent conductive oxide (TCO) surface, resulting in less availability for other functions such as tuning the wettability of the monolayer surface. In this work, we developed two anchorable molecules, 4PATTI‐C3 and 4PATTI‐C4, by employing a saddle‐like indole‐fused cyclooctatetraene as a π‐core with four phosphonic acid anchoring groups linked through propyl or butyl chains. Both molecules form monolayers on TCO substrates. Thanks to the saddle shape of a cyclooctatetraene skeleton, two of the four phosphonic acid anchoring groups were found to point upward, resulting in hydrophilic surfaces. Compared to the devices using 4PATTI‐C4 as the hole‐collecting monolayer, 4PATTI‐C3‐based devices exhibit a faster hole‐collection process, leading to higher power conversion efficiencies of up to 21.7 % and 21.4 % for a mini‐cell (0.1 cm2) and a mini‐module (1.62 cm2), respectively, together with good operational stability. This work represents how structural modification of multipodal molecules could substantially modulate the functions of the hole‐collecting monolayers after being adsorbed onto TCO substrates. [ABSTRACT FROM AUTHOR]

Meniscus injuries are common and while surgical strategies have improved, there is a need for alternative therapeutics to improve long-term outcomes and prevent post-traumatic osteoarthritis. Current research efforts in regenerative therapies and tissue engineering are hindered by a lack of understanding of meniscus cell biology and a poorly defined meniscus cell phenotype. This study utilized bulk RNA-sequencing to identify unique and overlapping transcriptomic profiles in cartilage, inner and outer zone meniscus tissue, and passaged inner and outer zone meniscus cells. The greatest transcriptomic differences were identified when comparing meniscus tissue to passaged monolayer cells (> 4,600 differentially expressed genes (DEGs)) and meniscus tissue to cartilage (> 3,100 DEGs). While zonal differences exist within the meniscus tissue (205 DEGs between inner and outer zone meniscus tissue), meniscus resident cells are more similar to each other than to either cartilage or passaged monolayer meniscus cells. Additionally, we identified and validated LUM, PRRX1, and SNTB1 as potential markers for meniscus tissue and ACTA2, TAGLN, SFRP2, and FSTL1 as novel markers for meniscus cell dedifferentiation. Our data contribute significantly to the current characterization of meniscus cells and provide an important foundation for future work in meniscus cell biology, regenerative medicine, and tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract Because of its dimensional characteristics, two-dimensional (2D) materials exhibit many special properties. The key to researching their features is to prepare high-quality larger-area monolayer 2D materials. Metal-assisted mechanical exfoliation method offers the possibility. However, there is still an unclear mechanism. We take transition metal dichalcogenides (TMD) as examples to perform serials of first-principles calculations to study their interlayer interaction. The calculated results demonstrate that the main factors affecting the interlayer interaction of 2D TMD materials include their structural features and the elemental features. The smaller interlayer distance between the topmost two layers than that of bulk leads to the stronger interlayer bonding energy, which results in the difficulty to exfoliate the large-area monolayer 2D crystals successfully. Further, we selected Ti, Cr and Au as the assisted metal due to their enhanced density of states near the Fermi level to calculate the adhesion energies of TMD on their surfaces. We found that there exists strong adhesion energy between 2D crystal and metal, which stretches the spacing of the topmost two layers and leads to the electron density rearrangement. Therefore, metal assisted mechanical exfoliation facilitates the successful preparation of monolayer 2D crystal.

Electronic and magnetic properties of transition metal (TM) ion-doped monolayer zinc oxide (ML-ZnO) have been analyzed using ab-initio calculations in the frame work of density functional theory. Spin–spin interaction study reveals that Cr, Mn, Fe and Cu doped at Zn site of ML-ZnO show stable ferromagnetic ordering along with the half-metallic behavior for most of the cases. The electronic and magnetic properties of the pristine system can also be modified by using co-doping. 3d orbital electrons of the dopants are primarily responsible for the origin of magnetic moment and the remaining part comes from the 3d and 2p orbital electrons of Zn and O atoms, respectively. Moreover, the magnetic ordering in Fe-doped ML-ZnO can change with the doping distance between the dopants. [ABSTRACT FROM AUTHOR]

Ultrafast thermally induced magnetization switching (TIMS) with femtosecond lasers has attracted much attention due to its ability to trigger a single switching on the picosecond time scale. Currently, most of the studies on TIMS have focused on various ferrimagnetic alloys. In this paper, TIMS of Gd/Fe multilayers in different monolayer ratios is investigated by atomic spin dynamics. The results show that an increase in the monolayer Gd ratio narrows the energy density window of the switching. Further studies found that a lower damping ratio decreases the laser energy density threshold for magnetization reversal. Moreover, reducing the ratio of Gd in the monolayer at the appropriate energy density can shorten the duration of the transient ferromagnetic-like state, which can lead to faster realization of TIMS. Our simulation results provide new insights to explore the physical mechanism of TIMS in Gd/Fe multilayers. [ABSTRACT FROM AUTHOR]

Dicarboxylate metallosurfactants (AASM), synthesized by mixing N‐dodecyl aminomalonate, ‐aspartate and ‐glutamate with CaCl2, MnCl2 and CdCl2, were characterized by XRD, FTIR, and NMR spectroscopy. Layered structures, formed by metallosurfactants, were evidenced from differential scanning calorimetry and thermogravimetric analyses. Solvent‐spread monolayer of AASM in combination with soyphosphatidylcholine (SPC) and cholesterol (CHOL) were studied using Langmuir surface balance. With increasing mole fraction of AASM mean molecular area increased and passed through maxima at ~60 mol% of AASMs, indicating molecular packing reorganization. Systems with 20 and 60 mol% AASM exhibited positive deviations from ideal behavior signifying repulsive interaction between the AASM and SPC, while synergistic interactions were established from the negative deviation at other combinations. Dynamic surface elasticity increased with increasing surface pressure signifying formation of rigid monolayer. Transition of monolayer from gaseous to liquid expanded to liquid condensed state was established by Brewster angle microscopic studies. Stability of the hybrid vesicles, formed by AASM+SPC+CHOL, were established by monitoring their size, zeta potential and polydispersity index values over 100 days. Size and spherical morphology of hybrid vesicles were confirmed by transmission electron microscopic studies. Biocompatibility of the hybrid vesicles were established by cytotoxicity studies revealing their possible applications in drug delivery and imaging. [ABSTRACT FROM AUTHOR]

MXene (Ti3C2Tx) is renowned for its exceptional conductivity and hydrophilicity; however, the low yield of monolayers hinders its industrial scalability. Herein, we present a strategy to substantially enhance the monolayer yield by disrupting the hydrogen‐bonding cage confinement of multilayer MXene using high‐temperature ultrasound, challenging the conventional belief that monolayer MXene can only be prepared at lower temperatures. At approximately 70 °C, the weakened hydrogen bonding between the oxygen‐containing terminal groups of multilayer MXene and surrounding water molecules weakens the hydrogen‐bond cage confinement. This enables ultrasonic cavitation to generate more microbubbles that penetrate the interlayers of multilayer MXene, resulting in gentle and thorough delamination into larger monolayer nanosheets. Achieving up to a 95 % yield in just tens of minutes, these nanosheets exhibit properties comparable to those produced by traditional ice‐bath methods. Furthermore, the high‐concentration MXene ink produced on a large scale using this high‐yield approach exhibits excellent printing and processing capabilities, and the corresponding products showcase superior infrared stealth and Joule heating characteristics. This work addresses a key technical bottleneck in MXene production, paving the way for its extensive technological and industrial applications. [ABSTRACT FROM AUTHOR]

Molecular platforms are essential components of various surface‐mounted molecular devices. Here, we document the synthesis of two universal triptycene‐based tripodal pedestals featuring terminal alkynes in the axial position. We showcase their versatility by incorporating them into the structures of diverse functional molecules such as unidirectional light‐driven molecular motors, photoswitches, and Brownian molecular rotors using standard cross‐coupling reactions. We also present their fundamental physical properties, including acidity constants, data from differential scanning calorimetry, and crystallographic analysis of two parent and five derived structures. Finally, and importantly, we demonstrate that the photochemical properties of selected photoswitch representatives remain uncompromised when fused with tripods. [ABSTRACT FROM AUTHOR]

The temperature dependences of the composition of the outer monolayers of the surface of thermoemitters, namely, oxide, scandate, thoriated tungsten, and carbide cathodes, have been studied by the methods of low-energy ion and recoil atom scattering, Auger spectroscopy, and secondary ion mass spectroscopy. It has been established that the surfaces of oxide, scandate, and tungsten-thorium cathodes at operating temperatures contain a monoatomic film of active material (barium, thorium), which forms on the surface of the emitter when heated to operating temperature and dissolves in volume when the temperature drops to room temperature. As a result of activation, free barium accumulates in the volume of oxide crystals. It is shown that there is a slight increase in tantalum on the surface of tantalum carbide and it contains foreign electronegative adatoms (oxygen, chlorine, and sulfur) that cannot be removed at temperatures of 2500 K. [ABSTRACT FROM AUTHOR]

Materials exhibiting charge density waves are attracting increasing attention owing to their complex physics and potential for applications. In this paper, we present a computational, first principles-based study of the Janus monolayer of 1T-TaSSe transition metal dichalcogenide. We extensively compare the results with those obtained for parent compounds, TaS2 and TaSe2 monolayers, with confirmed presence of 13 × 13 charge density waves. The structural and electronic properties of the normal (undistorted) phase and distorted phase with 13 × 13 periodic lattice distortion are discussed. In particular, for a normal phase, the emergence of dipolar moment due to symmetry breaking is demonstrated, and its sensitivity to an external electric field perpendicular to the monolayer is investigated. Moreover, the appearance of imaginary energy phonon modes suggesting structural instability is shown. For the distorted phase, we predict the presence of a flat, weakly dispersive band related to the appearance of charge density waves, similar to the one observed in parent compounds. The results suggest a novel platform for studying charge density waves in two-dimensional transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDCs) are among the most exciting materials in nano-size particles. In this study, MX2 (M = Mo and W; X = S, Se, and Te) nanotubes and monolayers were evaluated to show the structural, mechanical, and electronic properties. The results showed that the stability of MX2 monolayers changes similarly to nanotubes with the sequence of MS2 > MSe2 > MTe2 (M = Mo and W). Besides, MX2 nanotubes and monolayers are semiconductors, and the band gap energy increases with a similar sequence with stability properties. The structural stability and band gap energy of WX2 structures are more than MoX2 structures. Young's modulus of nanotubes was studied with density functional theory (DFT) and molecular dynamics (MD) simulations with Stillinger-Weber (SW) potential methods. The results are similar to the formation and band gap energy showing that Young's modulus of the MX2 structures is in order of MS2 > MSe2 > MTe2 (M = Mo and W) and WX2 > MoX2 (X = S, Se or Te). Structural defects in monolayers, which were M-vacancy (VM), X2-vacancy (VX2), M-X2-vacancy (VM-X2), and M-X4-vacancy (VM-X4), were studied and it showed that the mechanical properties could be decreased. However, the defects do not affect electronic properties. [ABSTRACT FROM AUTHOR]

Responding to global standards and legislative updates in Canada, including Bill S-5 (2023), toxicity testing is shifting towards more ethical, in vitro methods. Traditional two-dimensional (2D) monolayer cell cultures, limited in replicating the complex in vivo environment, have prompted the development of more relevant three-dimensional (3D) spheroidal hepatocyte cultures. This study introduces the first 3D spheroid model for McA-RH7777 cells, assessing xenobiotic receptor activation, cellular signaling, and toxicity against dexamethasone and naphthenic acid (NA)-fraction components; NAFCs. Our findings reveal that 3D McA-RH7777 spheroids demonstrate enhanced sensitivity and more uniform dose–response patterns in gene expression related to xenobiotic metabolism (AhR and PPAR) for both single compounds and complex mixtures. Specifically, 3D cultures showed significant gene expression changes upon dexamethasone exposure and exhibited varying degrees of sensitivity and resistance to the apoptotic effects induced by NAFCs, in comparison to 2D cultures. The optimization of 3D culture conditions enhances the model's physiological relevance and enables the identification of genomic signatures under varied exposures. This study highlights the potential of 3D spheroid cultures in providing a more accurate representation of the liver's microenvironment and advancing our understanding of cellular mechanisms in toxicity testing. [ABSTRACT FROM AUTHOR]

Single-layer molybdenum ditelluride (MoTe2) has attracted attention due to the smaller energy difference between the semiconducting (1H) and semimetallic (1T′) phases with respect to other two-dimensional transition metal dichalcogenides (TMDs). Understanding the phenomenon of polymorphism between these structural phases is of great fundamental and practical importance. In this paper, we report a 1H to 1T′ phase transition occurring during the chemical vapor deposition (CVD) synthesis of single-layer MoTe2 at 730 °C. The transformation originates at the heterocontact between monoclinic and hexagonal crystals and progresses to either yield a partial or complete 1H to 1T′ phase transition. Microscopic and spectroscopic analyses of the MoTe2 crystals reveal the presence of Te vacancies and mirror twin boundaries (MTB) domains in the hexagonal phase. The experimental observations and theoretical simulations indicate that the combination of heterocontact formation and Te vacancies are relevant triggering mechanisms in the observed transformation. By advancing in the understanding and controlling of the direct synthesis of lateral 1T′/1H heterostructures, this work contributes to the development of MoTe2-based electronic and optoelectronic devices with low contact resistance. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenide (TMDC) monolayers exhibit unique physical properties, such as self-terminating surfaces, a direct bandgap, and near-unity photoluminescence (PL) quantum yield (QY), which make them attractive for electronic and optoelectronic applications. Surface charge transfer has been widely used as a technique to control the concentration of free charge in 2D semiconductors, but its estimation and the impact on the optoelectronic properties of the material remain a challenge. In this work, we investigate the optical properties of a WS2 monolayer under three different doping approaches: benzyl viologen (BV), potassium (K), and electrostatic doping. Owing to the excitonic nature of 2D TMDC monolayers, the PL of the doped WS2 monolayer exhibits redshift and a decrease in intensity, which is evidenced by the increase in trion population. The electron concentrations of 3.79 × 10 13   cm − 2 , 6.21 × 10 13   cm − 2 , and 3.12 × 10 12   cm − 2 were measured for WS2 monolayers doped with BV, K, and electrostatic doping, respectively. PL offers a direct and versatile approach to probe the doping effect, allowing for the measurement of carrier concentration in 2D monolayer semiconductors. [ABSTRACT FROM AUTHOR]

The present study aimed to generate 3D spheroid cultures from three rainbow trout (RTE, RTK and RTS) cell lines by simple and reproducible methods and evaluated them for the propagation of fish viral pathogen for the first time. The 3D spheroids were generated in the present study by scaffold-free method using 3D-orbital shaker. The growth of spheroids was documented on each day until 15 days and their viability was assessed by using AO/EB and Hoechst 33258 fluorescent staining under bright field microscope. The successfully generated RTK spheroids (RTKs) from the RTK cells were further used for the propagation of SJNNV virus in direct comparison of viral growth with conventional 2D monolayer culture of RTK cell line. Immunofluorescent staining confirms the expression of SJNNV major capsid protein in infected RTK spheroid earlier than the RTK monolayer. The samples collected from both RTK spheroid and RTK monolayer at different days of post infection was confirmed by RT-PCR and their viral copy numbers found high in RTK spheroid while quantified by qRT-PCR. Further, SJNNV major capsid protein was confirmed by western blot and ELISA. The viral load obtained using RTK spheroid was found to be high when compared to the monolayer and this study suggests that the spheroid generated from RTK cells is more suitable in vitro tool that can be used for propagation of fish viral pathogens in large-scale for production of whole virus vaccine. [ABSTRACT FROM AUTHOR]

New amphiphilic block copolymers on based benzylmethacrylates or 2,3,4,5,6-pentafluorobenzyl methacrylate and N-isopropylacrylamide with high yields (89–94%) and MM 1.2∙105 and 1.63∙105 were synthesized. The relative constants of chain transfer to tris-(pentafluorophenyl)germanium during the radical polymerization of 2,3,4,5,6-pentafluorobenzyl methacrylate and benzylmethacrylate were 1.26 and 0.45, respectively. The structure of the copolymers was confirmed by IR and NMR spectroscopy. By the method of TGA analysis, the temperature of the beginning of decomposition of polymers was established, which amounted to 228.2 ºC and 150 ºC for the fluorinated and non-fluorinated block copolymer, respectively. The properties of polymers in solutions were studied by GPC, molecular hydrodynamics and optics. For both fluorinated and non-fluorinated samples, only macromolecules were observed in dilute solutions. The behavior of a non-fluorinated sample was well described as a coil in a good solvent, while fluorinated macromolecules were characterized by a compressed coil conformation, due to the presence of fluorine in the polymer structure. It was shown that the block copolymers formed stable Langmuir monolayers with high surface pressures (50–58 mN/m), and the transferred Langmuir–Blodgett films on silicon wafers were hydrophilic (water contact angles are 68–73 ºC). A large hysteresis loop on the surface pressure isotherm obtained under compression-expansion conditions for a fluorinated block copolymer indicates significant inter- and intramolecular interactions at the water–air interface. [ABSTRACT FROM AUTHOR]

Abstract At elevated temperatures, the prototypical organic solvents used to study the self‐assembly of supramolecular monolayers at liquid–solid interfaces alter a graphite substrate by intercalation. As a consequence, less strongly bound supramolecular monolayers become thermodynamically unstable, as probed by scanning tunneling microscopy. Complementary characterization by atomic force microscopy, confocal Raman spectroscopy and low energy electron microscopy consistently points to subsurface changes in the top few layers of the graphite substrate due to solvent intercalation. High‐temperature annealing at 900 °C in the vacuum restores the adsorption properties of the graphite substrates, indicating a high activation energy for deintercalation. However, strongly adsorbing hydrogen‐bonded monolayers of trimesic acid inhibit solvent intercalation and thus protect the graphite substrate. Mildly solvent‐intercalated graphite may prove useful as an easily prepared graphitic material with further weakened adsorption properties.

Fabricating heterojunctions with precisely controlled interfacial structures is crucial for exploring novel low-dimensional physics and for realizing high-performance devices. However, such capabilities are often constrained by contamination from the ambient environment or by the limitations of applicable methods and materials under vacuum conditions. In this study, MoS2/Au(111) heterostructures were fabricated by exfoliating MoS2 thin layers onto a crystallized Au(111) surface using a gold-assisted exfoliation method in an ultra-high vacuum environment. This method yields millimeter-sized monolayer or sub-millimeter-sized bilayers with contamination-free interfaces, which are unattainable for samples made in air. Scanning tunneling microscopy revealed that both the monolayer and the bilayer exhibit uniform and well-ordered moiré superlattices controlled by the twisting angle between the Au(111) surface and the MoS2 overlayer. The direct contact with the Au surface renders the monolayer MoS2 weakly metallic, while a less coupled bilayer is semiconducting, indicating a 0.54 eV Schottky barrier for the MoS2/Au(111) contact. This method is applicable to various combinations of van der Waals materials and metal surfaces. The uniform and controllable heterojunctions can serve as ideal model systems for exploring semiconductor–metal interfaces and atomic structures formed within.

IntroductionPeriodontitis, affecting approximately 3.9 billion individuals globally, significantly impacts quality of life and has raised interest in its potential systemic effects. Sodium perborate, a common component in oral care products for biofilm control, is widely used, though concerns about its safety persist. This study aimed to evaluate the in vitro toxicity of six commercial oral care products and varying concentrations of sodium perborate, utilizing human gingival fibroblasts (HGF) and keratinocytes (HaCat) as cell models.MethodsExperiments were performed in both 2D monolayer and 3D cultures using MTT and electrical impedance assays, adhering to the manufacturer’s recommended exposure time of 30–60 s for product testing. For the reconstructed epidermis model, a prolonged exposure time of 42 min was applied, following the Organization for Economic Cooperation and Development (OECD) Test Guideline 439.ResultsResults indicated that all products and sodium perborate at 1 mg/mL were cytotoxic in monolayer cultures. However, at concentrations relevant to commercial formulations (0.06 mg/mL sodium perborate), no significant toxicity was observed. In contrast, the 3D culture models, including spheroids and reconstructed epidermis, exhibited minimal to no cytotoxic effects for the commercial products, with sodium perborate showing no significant toxicity below 0.1 mg/mL. The reconstructed epidermis model, used as surrogate for oral mucosa, further confirmed that the products were non-irritating, in compliance with OECD TG 439 standards.DiscussionThis study highlights the importance of considering exposure time, dosage, and cellular model when assessing the safety of oral care products. While 2D models are useful for preliminary screenings, 3D models provide a more physiologically relevant assessment, emphasizing the need for robust testing protocols to ensure product safety.

The monolayer (two-dimensional or 2D) cell culture, while widely used, lacks fidelity in replicating vital cell interactions seen in vivo, leading to a shift toward three-dimensional (3D) models. Although monolayers offer simplicity and cost-effectiveness, spheroids mimic cellular environments better. This is due to its nutrient gradients, which influence drug penetration and provide a more accurate reflection of clinical scenarios than monolayers. Consequently, 3D models are crucial in drug development, especially for anti-cancer therapeutics, enabling the screening of cell cycle inhibitors and combination therapies vital for heterogeneous tumor populations. Inhibiting processes like migration and invasion often require drugs targeting the cytoskeleton, which can exhibit dual functionality with cell cycle inhibitors. Therapeutic approaches with promising anti-cancer potential often exhibit reduced efficacy in 3D cell culture compared to their performance in monolayer settings, primarily due to the heightened complexity inherent in this system. In the face of this scenario, this review aims to survey existing knowledge on compounds utilized in both 2D and 3D cell cultures, assessing their responses across different culture types and discerning the implications for drug screening, particularly those impacting the cell cycle and cytoskeletal dynamics.

Abstract Since the discovery of the extraordinary optical transmission phenomenon, nanohole arrays have attracted much attention and been widely applied in sensing. However, their typical fabrication process, utilizing photolithographic top-down manufacturing technologies, has intrinsic drawbacks including the high costs, time consumption, small footprint, and low throughput. This study presented a low-cost, high-throughput, and scalable method for fabricating centimeter-scale (1×2 cm2) nanohole arrays using the improved nanosphere lithography. The large-scale close-packed polystyrene monolayers obtained by the hemispherical-depression-assisted self-assembly method were employed as colloidal masks for the nanosphere lithography, and the nanohole diameter was tuned from 233 nm to 346 nm with a fixed period of 420 nm via plasma etching. The optical properties and sensing performance of the nanohole arrays were investigated, and two transmission dips were observed due to the resonant coupling of plasmonic modes. Both dips were found to be sensitive to the surrounding environment, and the maximum bulk refractive index sensitivity was up to 162.1 nm/RIU with a 233 nm hole diameter. This study offered a promising approach for fabricating large-scale highly ordered nanohole arrays with various periods and nanohole diameters that could be used for the development of low-cost and high-throughput on-chip plasmonic sensors.

Understanding the thermoelastic response of a nanostructure is crucial for the choice of materials and interfaces in electronic devices with improved and tailored transport properties at the nanoscale. Here, we show how the deposition of a MoS2 monolayer can strongly modify the nanoscale thermoelastic dynamics of silicon substrates close to their interface. We demonstrate this by creating a transient grating with extreme ultraviolet light, using ultrashort free-electron laser pulses, whose ≈84 nm period is comparable to the size of elements typically used in nanodevices, such as electric contacts and nanowires. The thermoelastic response, featuring coherent acoustic waves and incoherent relaxation, is tangibly modified by the presence of monolayer MoS2. Namely, we observed a major reduction of the amplitude of the surface mode, which is almost suppressed, while the longitudinal mode is basically unperturbed, aside from a faster decay of the acoustic modulations. We interpret this behavior as a selective modification of the surface elasticity, and we discuss the conditions to observe such effect, which may be of immediate relevance for the design of Si-based nanoscale devices. [ABSTRACT FROM AUTHOR]

Covalent organic framework (COF) monolayers, with atomically thin, ordered networks, and rich functionality, are widely studied due to their unusual structure/property relationships. However, synthesizing COF monolayer has remained an unmet challenge due to the difficulty of controlling reactions at the monolayer limit with large-scale uniformity. The identification and development of new reactions and polymerization conditions are critical for the further advancement of COF monolayer materials. Moreover, as one-molecule-thick a freestanding films, COF monolayer offers an ideal material system. Many advanced applications of COF monolayer have been explored in recent literature. This review provides an overview of the current state of precise synthetic strategies for COF monolayer, highlighting the advantages and limitations of different synthetic approaches and key challenges related to enhancing quality, and emphasizing the unique benefits of COF monolayer as both an ideal model system and for advanced applications. [ABSTRACT FROM AUTHOR]

The monolayer (two-dimensional or 2D) cell culture, while widely used, lacks fidelity in replicating vital cell interactions seen in vivo, leading to a shift toward three-dimensional (3D) models. Although monolayers offer simplicity and cost-effectiveness, spheroids mimic cellular environments better. This is due to its nutrient gradients, which influence drug penetration and provide a more accurate reflection of clinical scenarios than monolayers. Consequently, 3D models are crucial in drug development, especially for anti-cancer therapeutics, enabling the screening of cell cycle inhibitors and combination therapies vital for heterogeneous tumor populations. Inhibiting processes like migration and invasion often require drugs targeting the cytoskeleton, which can exhibit dual functionality with cell cycle inhibitors. Therapeutic approaches with promising anti-cancer potential often exhibit reduced efficacy in 3D cell culture compared to their performance in monolayer settings, primarily due to the heightened complexity inherent in this system. In the face of this scenario, this review aims to survey existing knowledge on compounds utilized in both 2D and 3D cell cultures, assessing their responses across different culture types and discerning the implications for drug screening, particularly those impacting the cell cycle and cytoskeletal dynamics. [ABSTRACT FROM AUTHOR]

The optical response of a two-dimensional supercrystal (monolayer) of quantum emitters with a doublet in the excited state to the action of a continuous external field was theoretically studied, considering the dephasing of the electronic states of the system. The secondary field acting on the V-emitter from other V-emitters of the system forms their nonlinearity and provides internal positive feedback, which leads to bistability and periodic and aperiodic self-oscillations, including chaotic behavior. In the presence of dephasing, the multistability of the optical response is preserved. Phase relaxation leads to a change in the scenario of the system dynamics from chaos to periodic oscillations of the field amplitude, i.e., to a chaos–limit cycle bifurcation and to a decrease in the reflectivity of the monolayer in linear and nonlinear modes. [ABSTRACT FROM AUTHOR]

Superconducting phase transitions in two dimensions lie beyond the description of the Ginzburg-Landau symmetry-breaking paradigm for three-dimensional superconductors. They are Berezinskii-Kosterlitz-Thouless (BKT) transitions of paired-electron condensate driven by the unbinding of topological excitations, i.e. vortices. The recently discovered monolayers of layered high-transition-temperature (⁠|${{{T}}}_{{\rm C}}$|⁠) cuprate superconductor Bi2Sr2CaCu2O8+δ (Bi2212) meant that this 2D superconductor promised to be ideal for the study of unconventional superconductivity. But inhomogeneity posed challenges for distinguishing BKT physics from charge correlations in this material. Here, we utilize the phase sensitivity of scanning superconducting quantum interference device microscopy susceptometry to image the local magnetic response of underdoped Bi2212 from the monolayer to the bulk throughout its phase transition. The monolayer segregates into domains with independent phases at elevated temperatures below |${{{T}}}_{{\rm C}}$|⁠. Within a single domain, we find that the susceptibility oscillates with flux between diamagnetism and paramagnetism in a Fraunhofer-like pattern up to |${{{T}}}_{{\rm C}}$|⁠. The finite modulation period, as well as the broadening of the peaks when approaching |${{{T}}}_{{\rm C}}$| from below, suggests well-defined vortices that are increasingly screened by the dissociation of vortex-antivortex plasma through a BKT transition. In the multilayers, the susceptibility oscillation differs in a small temperature regime below |${{{T}}}_{{\rm C}}$|⁠ , consistent with a dimensional crossover led by interlayer coupling. Serving as strong evidence for BKT transition in the bulk, we observe a sharp jump in phase stiffness and paramagnetism at small fields just below |${{{T}}}_{{\rm C}}$|⁠. These results unify the superconducting phase transitions from the monolayer to the bulk underdoped Bi2212, and can be collectively referred to as the BKT transition with interlayer coupling. [ABSTRACT FROM AUTHOR]

Based on several clinical observations it was hypothesized that herpesviruses may influence the replication of human bocaviruses, the second known parvoviruses that have been confirmed as human pathogens. While several cell lines support the growth of HSV-1, HBoV-1 was exclusively cultivated on air–liquid interface cultures, the latter being a rather complicated, slow, and low throughput system. One of the cell lines are T84 cells, which are derived from the lung metastasis of a colorectal tumor. In this study, we provide evidence that T84 also supports HBoV replication when cultivated as monolayers, while simultaneously being permissive for HSV-1. The cell culture model thus would enable co-infection studies of both viruses and is worth being optimized for high throughput studies with HBoV-1. Additionally, the study provides evidence for a supporting effect of HSV-1 on the replication and packaging of HBoV-1 progeny DNA into DNase-resistant viral particles. [ABSTRACT FROM AUTHOR]

Abstract The intestinal epithelium is a dynamic barrier that allows the selective exchange of ions, hormones, proteins, and nutrients. To accomplish this, the intestinal epithelium adopts a highly columnar morphology which is partially lost in submerged culturing systems. To achieve this, small intestinal tissue samples were utilized to obtain human intestinal crypts to form enteroids. The Transwell system was subsequently employed to form a monolayer of cells that was cultured in either the submerged condition or the air–liquid Interface (ALI) condition. We found that the human intestinal monolayer under the ALI condition exhibited morphology more similar to the normal intestinal epithelium. F‐actin localization and brush border formation were observed apically, and the integrity of the tight junctions was preserved in the ALI condition. Fewer apoptotic cells were observed in the ALI conditions as compared to the submerged conditions. The monolayer of cells expressed a higher level of secretory cell lineage genes in the ALI condition. The ALI condition positively contributes toward a more differentiated phenotype of epithelial cells. It serves as an amplifier that enhances the existing differentiation cue. The ALI system provides a more differentiated platform to study intestinal function compared to submerged conditions.

Abstract Stem cell-derived organoid cultures have emerged as attractive experimental models for infection biology research regarding various types of gastro-intestinal pathogens and host species. However, the large size of infectious nematode larvae and the closed structure of 3-dimensional organoids often hinder studies of the natural route of infection. To enable easy administration to the apical surface of the epithelium, organoids from the equine small intestine, i.e. enteroids, were used in the present study to establish epithelial monolayer cultures. These monolayers were functionally tested by stimulation with IL-4 and IL-13, and/or exposure to infectious stage larvae of the equine nematodes Parascaris univalens, cyathostominae and/or Strongylus vulgaris. Effects were recorded using transcriptional analysis combined with histochemistry, immunofluorescence-, live-cell- and scanning electron microscopy. These analyses revealed heterogeneous monolayers containing both immature and differentiated cells including tuft cells and mucus-producing goblet cells. Stimulation with IL-4/IL-13 increased tuft- and goblet cell differentiation as demonstrated by the expression of DCLK1 and MUC2. In these cytokine-primed monolayers, the expression of MUC2 was further promoted by co-culture with P. univalens. Moreover, live-cell imaging revealed morphological alterations of the epithelial cells following exposure to larvae even in the absence of cytokine stimulation. Thus, the present work describes the design, characterization and usability of an experimental model representing the equine nematode-infected small intestinal epithelium. The presence of tuft cells and goblet cells whose mucus production is affected by Th2 cytokines and/or the presence of larvae opens up for mechanistic studies of the physical interactions between nematodes and the equine intestinal mucosa.

We have investigated the morphology of two-dimensional monolayers of gramicidin-D (GD) and alamethicin (Al) formed on the water surface by the dropping method (DM) using surface tension measurement (STm), Brewster angle microscopy (BAM), and atomic force microscopy (AFM). Dynamic light scattering (DLS) revealed that GD in alcoholic solutions formed a dimeric helical structure. According to the CD and NMR spectroscopies, GD molecules existed in dimer form in methanol and lipid membrane environments. The STm results and BAM images revealed that the GD dimer monolayer was in a liquid expanded (LE) state, whereas the Al monolayer was in a liquid condensed (LC) state. The limiting molecular area (A0) was 6.2 ± 0.5 nm2 for the GD-dimer and 3.6 ± 0.5 nm2 for the Al molecule. The AFM images also showed that the molecular long axes of both the GD-dimer and Al were horizontal to the water surface. The stability of each monolayer was confirmed by the time dependence of the surface pressure (π) observed using the STm method. The DM monolayer preparation method for GD-dimer and Al peptide molecules is a useful technique for revealing how the model biological membrane's components assemble in two dimensions on the water surface. [ABSTRACT FROM AUTHOR]

N‐heterocyclic carbene (NHC) monolayers are transforming electrocatalysis and biosensor design via their increased performance and stability. Despite their increasing use in electrochemical systems, the integrity of the NHC monolayer during voltage perturbations remains largely unknown. Herein, we deploy surface‐enhanced Raman spectroscopy (SERS) to measure the stability of two model NHCs on gold in ambient conditions as a function of applied potential and under continuous voltammetric interrogation. Our results illustrate that NHC monolayers exhibit electrochemical stability over a wide voltage window (−1 V to 0.5 V vs Ag|AgCl), but they are found to degrade at strongly reducing (< −1 V) or oxidizing (>0.5 V) potentials. We also address NHC monolayer stability under continuous voltammetric interrogation between 0.2 V and −0.5 V, a commonly used voltage window for sensing, showing they are stable for up to 43 hours. However, we additionally find that modifications of the backbone NHC structure can lead to significantly shorter operational lifetimes. While these results highlight the potential of NHC architectures for electrode functionalization, they also reveal potential pitfalls that have not been fully appreciated in electrochemical applications of NHCs. [ABSTRACT FROM AUTHOR]

By using the first-principles calculations established on density functional theory (DFT), the electronic aspects of the tetrahexcarbon (TH-carbon) monolayer as a two-dimensional carbon allotrope which is a direct bandgap semiconductor have been investigated under variations of buckling parameter (σ = 0 , 2 , 4 , 6) by the PBE-GGA. Also, optical properties of this nanosheet are projected in out-of-plane polarization in buckling variation situations up to σ = 6. Its optic behaviors in the visible light spectrum match its electronic ones. The results propose that the TH-carbon monolayer is an appropriate material for designing optoelectronic devices. [ABSTRACT FROM AUTHOR]

Multielectrode arrays (MEAs) are the method of choice for electrophysiological characterization of cardiomyocyte monolayers. The field potentials recorded using an MEA are like extracellular electrograms recorded from the myocardium using conventional electrodes. Nevertheless, different criteria are used to interpret field potentials and extracellular electrograms, which hamper correct interpretation and translation to the patient. To validate the criteria for interpretation of field potentials, we used neonatal rat cardiomyocytes to generate monolayers. We recorded field potentials using an MEA and simultaneously recorded action potentials using sharp microelectrodes. In parallel, we recreated our experimental setting in silico and performed simulations. We show that the amplitude of the local RS complex of a field potential correlated with conduction velocity in silico but not in vitro. The peak time of the T wave in field potentials exhibited a strong correlation with APD90 while the steepest upslope correlated well with APD50. However, this relationship only holds when the T wave displayed a biphasic pattern. Next, we simulated local extracellular action potentials (LEAPs). The shape of the LEAP differed markedly from the shape of the local action potential, but the final duration of the LEAP coincided with APD90. Criteria for interpretation of extracellular electrograms should be applied to field potentials. This will provide a strong basis for the analysis of heterogeneity in conduction velocity and repolarization in cultured monolayers of cardiomyocytes. Finally, a LEAP is not a recording of the local action potential but is generated by intracellular current provided by neighboring cardiomyocytes and is superior to field potential duration in estimating APD90. [ABSTRACT FROM AUTHOR]