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The class of two-dimensional oxyfluoride monolayers is currently considered one of the most attractive nanomaterials for enhancing design and pushing the limits of different cutting-edge technologies. Two-dimensional semiconductor materials are the most promising systems for various applications in optoelectronic devices because they have a unique optical properties. We continue in this way by investigating the GW band structures and optical properties of unique 2D XOF (X = Ga or In) oxyfluoride monolayers, involving absorption, conductivity, refractive index, and dielectric function. We find no imaginary frequencies in the computed phonon spectra, indicating that these systems are dynamically stable. Furthermore, GaOF and InOF stay stable for temperatures T ≤ 840 K. The band gap of GaOF obtained with the single shot (G0W0) is larger than the band gap energy Eg of InOF. Where the direct band gap energies of GaOF and InOF are 6.1 eV and 4.8 eV, respectively. Our GW(PBE) numerical simulations demonstrate that the GaOF monolayer moves transparent once the frequency of the incoming light exceeds the plasma frequency (35.00 eV). Furthermore, InOF switches transparently once the incident light frequency exceeds the plasma frequency ∼ 35.00 eV. Interestingly, we obtain that these 2D sheets have a strong absorption coefficient in the range of ∼ 3.00–60.00 eV. They are emerging as a potential for the building blocks of the nano-size and ultra-thin optoelectronics of the future since they productively emit and absorb light.

Sequentially timed all-optical mapping photography is one of the main emerging ultra-fast detection technologies that can be widely applicable to ultra-fast detection at the picosecond level in fields such as materials and life sciences. We propose a new optical structure for an all-optical spatial mapping module that can control the optical field of two-dimensional imaging while improving spectral resolution and detector sensor utilization. The model of optical parameters based on geometrical optics theory for the given structure has been established, and the theoretical analysis of the inter-frame energy crosstalk caused by incident beam spot width, chromatic aberration, and main errors of the periscope array has been conducted. The optical design of the two-dimensional (2D) all-optical spatial mapping module was finally completed using ZEMAX OpticStudio 2018 software. The results show that our optical module can realize targets of 16 frames and 1.25 nm spectral resolution.

This article explores the novel application of a trained artificial neural network (ANN) in the prediction of vanadium redox flow battery behaviour and compares its performance with that of a two-dimensional numerical model. The aim is to evaluate the capability of two ANNs, one for predicting the cell potential and one for the overpotential under various operating conditions. The two-dimensional model, previously validated with experimental data, was used to generate data to train and test the ANNs. The results show that the first ANN precisely predicts the cell voltage under different states of charge and current density conditions in both the charge and discharge modes. The second ANN, which is responsible for the overpotential calculation, can accurately predict the overpotential across the cell domains, with the lowest confidence near high-gradient areas such as the electrode membrane and domain boundaries. Furthermore, the computational time is substantially reduced, making ANNs a suitable option for the fast understanding and optimisation of VRFBs.

All social insects with obligate reproductive division of labor evolved from strictly monogamous ancestors, but multiple queen-mating (polyandry) arose de novo, in several evolutionarily derived lineages. Polyandrous ant queens are inseminated soon after hatching and store sperm mixtures for a potential reproductive life of decades. However, they cannot re-mate later in life and are thus expected to control the loss of viable sperm because their lifetime reproductive success is ultimately sperm limited. In the leaf-cutting ant Atta colombica,, the survival of newly inseminated sperm is known to be compromised by seminal fluid of rival males and to be protected by secretions of the queen sperm storage organ (spermatheca). Here we investigate the main protein-level interactions that appear to mediate sperm competition dynamics and sperm preservation. We conducted an artificial insemination experiment and DIGE-based proteomics to identify proteomic changes when seminal fluid is exposed to spermathecal fluid followed by a mass spectrometry analysis of both secretions that allowed us to identify the sex-specific origins of the proteins that had changed in abundance. We found that spermathecal fluid targets only seven (2%) of the identified seminal fluid proteins for degradation, including two proteolytic serine proteases, a SERPIN inhibitor, and a semen-liquefying acid phosphatase. In vitro, and in vivo, experiments provided further confirmation that these proteins are key molecules mediating sexual conflict over sperm competition and viability preservation during sperm storage. In vitro, exposure to spermathecal fluid reduced the capacity of seminal fluid to compromise survival of rival sperm in a matter of hours and biochemical inhibition of these seminal fluid proteins largely eliminated that adverse effect. Our findings indicate that A. colombica, queens are in control of sperm competition and sperm storage, a capacity that has not been documented in other animals but is predicted to have independently evolved in other polyandrous social insects.

Background and Objectives: The use of two-dimensional materials in the photodetector fabrication has received much attention in recent years. Graphene is a two-dimensional material that has been extensively researched to make photodetectors. The responsivity of graphene photodetectors was limited by the low optical absorption in graphene (~2.3% for single layer graphene). Therefore, graphene along with other materials has been used to fabricate a photodetector with the desired properties. The graphene is used for the improvement of the silicide platinum photodetector.Methods: The platinum silicide photodetector with graphene has been experimentally fabricated and characterized, and all steps of the device fabrication and the characterization are completely provided in addition to required equations for device analysis is completely provided. A graphene layer is transferred on the platinum silicide layer, and the graphene layer creates the photoconductor gain in the platinum silicide photodetector. Results: In the proposed device, near-infrared light is detected in the platinum silicide, and by placing a layer of graphene on the platinum silicide, the optical current and responsivity increase compared to the platinum silicide photodetector without graphene. Experimental results show that the optical current, external quantum efficiency, and responsivity increase in the platinum silicide photodetector with graphene. The graphene not only functions as the charge transport channel, but also works as a photoconductor.Conclusion: The optical current and responsivity are increased by the platinum silicide photodetector with graphene. In our photodetector, the highest responsivity is 120 mA/W in the 1310 nm wavelength, and the optical current is 100 nA at the applied voltage of 8 V. Our photodetector has optical current, responsivity, and external quantum efficiency twice as much as platinum silicide photodetector. Experimental results show the good performance of graphene with platinum silicide photodetector.

We introduce a new efficient spectral element approach to solve the two-dimensional magnetotelluric forward problem based on Gauss–Lobatto–Legendre polynomials. It combines the high accuracy of the spectral technique and the perfect flexibility of the finite element approach, which can significantly improve the calculation accuracy. This method mainly includes two steps: 1) transforming the boundary value problem in the partial differential form into the variational problem in the integral form and 2) solving large symmetric sparse systems based on the combination of incomplete LU factorization and the double conjugate gradient stability algorithm through the spectral element with quadrilateral meshes. We imply the spectral element method on a resistivity half-space model to obtain a simple analytical solution and find that the magnetic field solutions simulated by the spectral element approach matched closely to the exact solutions. The experiment result shows that the spectral element solution has high accuracy with coarse meshes. We further compare the numerical results of the spectral element, finite difference, and finite element approaches on the COMMEMI 2D-1 and smooth models, respectively. The numerical results of the spectral element procedure are highly consistent with the other two techniques. All these comparison results suggest that the spectral element technique can not only give high accuracy for modeling results but also provide more detailed information. In particular, a few nodes are required in this method relative to the finite difference and finite element methods, which can decrease the relative errors. We then deduce that the spectral element method might be an alternative approach to simulate the magnetotelluric responses in two- or three-dimensional structures.

This study presents two-dimensional dam break numerical modeling through an urban area. There are three approaches to defining a building in numerical modeling, as a wall boundary, contour, and Manning, which have been widely used. However, there is no research that compares and evaluates the accuracy of each approach. Thus, this study aims to determine the best approach, in term of accuracy, and evaluate its reliability by comparing the numerical modeling approach's results to experiment results. The model was developed based on the Saint-Venant equations, then solved using the MacCormack method with a numerical filter. The authors first utilized a single-building experiment to determine the best approach. The results indicated that the wall boundary approach had the highest accuracy based on MDAPE, with the lowest value of 13.47%, followed by Manning with 16.48%, and Contour with 21.46%. A multiple-building case is then used to evaluate the best approach's reliability. The results show high similarity to the experiment results. However, the wall boundary approach cannot be used when the building is submerged or has a height variation, since these approaches cannot define the building's height. Moreover, Manning approach cannot be considered as a building approach, since the approach does not reflect the behaviour of the building. Thus, the authors recommend the wall boundary approach when the building does not have a height variation and is not submerged, and the contour approach otherwise.

We constructed two-dimensional NiCo-metal–organic-framework (NiCo-MOF) nanosheets based on a facile protocol and then characterized them using multiple approaches (X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), field emission-scanning electron microscopy (FE-SEM), and N2 adsorption/desorption isotherms techniques). As a sensitive electroactive material, the as-fabricated bimetallic NiCo-MOF nanosheets were employed to modify a screen-printed graphite electrode surface (NiCo-MOF/SPGE) for epinine electro-oxidation. According to the findings, there was a great improvement in the current responses of the epinine because of the appreciable electron transfer reaction and catalytic performance of the as-produced NiCo-MOF nanosheets. Differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry were utilized to analyze the electrochemical activity of the epinine on the NiCo-MOF/SPGE. A linear calibration plot was obtained in the broad concentration range (0.07–335.0 µM) with a high sensitivity (0.1173 µA/µM) and a commendable correlation coefficient (0.9997). The limit of detection (S/N = 3) was estimated at 0.02 µM for the epinine. According to findings from DPV, the electrochemical sensor of the NiCo-MOF/SPGE could co-detect epinine and venlafaxine. The repeatability, reproducibility and stability of the NiCo-metal–organic-framework-nanosheets-modified electrode were investigated, and the relative standard deviations obtained indicated that the NiCo-MOF/SPGE had superior repeatability, reproducibility and stability. The as-constructed sensor was successfully applicable in sensing the study analytes in real specimens. [ABSTRACT FROM AUTHOR]

Background Canine mammary gland tumors can be used as predictive models for human breast cancer. There are several types of microRNAs common in human breast cancer and canine mammary gland tumors. The functions of microRNAs in canine mammary gland tumors are not well understood. Methods We compared the characterization of microRNA expression in two-dimensional and threedimensional canine mammary gland tumor cell models. We evaluated the differences between two- and threedimensional cultured canine mammary gland tumor SNP cells by assessing microRNA expression levels, morphology, drug sensitivity, and hypoxia. Results The expression of microRNA-210 in the three-dimensional-SNP cells was 10.19 times higher than that in the two-dimensional-SNP cells. The intracellular concentrations of doxorubicin in the twoand three-dimensional-SNP cells were 0.330 ± 0.013 and 0.290 ± 0.048 nM/mg protein, respectively. The IC50 values of doxorubicin for the two- and threedimensional- SNP cells were 5.2 and 1.6 µM, respectively. Fluorescence of the hypoxia probe, LOX-1, was observed inside the sphere of three-dimensional-SNP cells without echinomycin but not in two-dimensional- SNP cells. The three-dimensional-SNP cells treated with echinomycin showed weak LOX-1 fluorescence. Conclusion The present study showed a clear difference in microRNA expression levels in cells cultured in a two-dimensional adherent versus a three-dimensional spheroid model. [ABSTRACT FROM AUTHOR]

The low-dimensional organic-inorganic halide perovskites with self-trapped exciton emission have promising prospects for single-phase white-light emitters. However, so far, these broadband white-light-emitting (BWLE) perovskites were synthesized by trial-and-error testing spacing molecules. Here, we developed a steric hindrance regulation strategy to predictably synthesize BWLE perovskites. The molecules containing C–C(–NH2)–C groups were introduced into low-dimensional perovskites, which brings a large steric hindrance in-plane orientation. The bigger C–C(–NH2)–C bond angle would induce larger structural distortion in perovskites, which leads to the higher rate of self-trapping of excitons and the deeper self-trapping depth. The photoluminescence spectra of the synthesized perovskites can cover the cool-to-warm white light region. Overall, we fabricated a material library consisting of 40 kinds of BWLE compounds according to this strategy. Our findings develop a general strategy to synthesize BWLE perovskites and offer a material platform for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Atomically thin transition metal dichalcogenides (TMDs), like MoS2 with high carrier mobilities and tunable electron dispersions, are unique active material candidates for next generation opto-electronic devices. Previous studies on ion irradiation show great potential applications when applied to two-dimensional (2D) materials, yet have been limited to micron size exfoliated flakes or smaller. To demonstrate the scalability of this method for industrial applications, we report the application of relatively low power (50 keV) 4He+ ion irradiation towards tuning the optoelectronic properties of an epitaxially grown continuous film of MoS2 at the wafer scale, and demonstrate that precise manipulation of atomistic defects can be achieved in TMD films using ion implanters. The effect of 4He+ ion fluence on the PL and Raman signatures of the irradiated film provides new insights into the type and concentration of defects formed in the MoS2 lattice, which are quantified through ion beam analysis. PL and Raman spectroscopy indicate that point defects are generated without causing disruption to the underlying lattice structure of the 2D films and hence, this technique can prove to be an effective way to achieve defect-mediated control over the opto-electronic properties of MoS2 and other 2D materials. [ABSTRACT FROM AUTHOR]

A compact model able to predict the electrical read-out of field-effect biosensors based on two-dimensional (2D) semiconductors is introduced. It comprises the analytical description of the electrostatics including the charge density in the 2D semiconductor, the site-binding modeling of the barrier oxide surface charge, and the Stern layer plus an ion-permeable membrane, all coupled with the carrier transport inside the biosensor and solved by making use of the Donnan potential inside the ion-permeable membrane formed by charged macromolecules. This electrostatics and transport description account for the main surface-related physical and chemical processes that impact the biosensor electrical performance, including the transport along the low-dimensional channel in the diffusive regime, electrolyte screening, and the impact of biological charges. The model is implemented in Verilog-A and can be employed on standard circuit design tools. The theoretical predictions obtained with the model are validated against measurements of a MoS2 field-effect biosensor for streptavidin detection showing excellent agreement in all operation regimes and leading the way for the circuit-level simulation of biosensors based on 2D semiconductors. [ABSTRACT FROM AUTHOR]

We use a dielectric-response formalism to compute the induced charge density and the induced potential in a conductive two-dimensional (2D) material, traversed by a charged particle that moves on a perpendicular trajectory with constant velocity. By analyzing the electric force on the material via the Maxwell stress tensor, we showed that the polarization of the material can be decomposed into a conservative part related to the dynamic image force, and a dissipative part describing the energy and momentum transfer to the material, which is ultimately responsible for launching the plasma oscillation waves in the material. After showing that the launching dynamics is fully determined by the Loss function of the material, we used a conductivity model suitable for the terahertz to the midinfrared frequency range, which includes both the intraband and interband electron transitions in the material, to compute the real-space and time animations of the propagating plasma waves in the plane of the material. Finally, we used a stationary phase analysis to show that the plasmon wave crests go into an overdamped regime at large propagation distances, which are comparable to the distances where retardation effects are expected to emerge due to hybridization of the plasmon dispersion with the light line at long wavelengths. [ABSTRACT FROM AUTHOR]

In this work, a new two-dimensional method is presented for turbine volute design. In this method, the continuity equation, energy equation, free vortex equation, and streamline equation are employed to solve the velocity field and to generate the volute profile. The physical model and mathematic solution to the governing equations are described in detail. A new volute for a turbocharger turbine is generated using this method and compared with the original, well-designed baseline volute. Different turbine operating conditions, including equal and unequal admission cases, were studied by CFD to compare turbine aerodynamic performance using the new and baseline volutes. The simulation results show that the efficiency of the new volute is about 0.4%–0.6% higher than the baseline under equal admission conditions. It is found that the improvement in turbine performance is mainly due to the more reasonable A/R distribution, which reduces the losses in the turbine. This work demonstrates that the proposed new method provides an effective way for radial turbine volute design, and can quickly create high performance volutes. [ABSTRACT FROM AUTHOR]

A taxonomy for s p 2 carbon allotropes in two dimensions (2D) is proposed where single-layer structures are assigned a unique symbol associated with the geometry of each allotrope. The naming scheme is demonstrated for structures described in the literature and is further illustrated for a number of other topology-allowed s p 2 carbon systems. The symbol is easy to use and gives a direct access to geometrical features such as the number of polygons and their arrangement. It facilitates the classification of structures reported in the literature, where many such structures are found to have been assigned a name based on each author's somewhat arbitrary choice. This naming scheme will help rationalize future studies on this class of systems. A comparative study of the energetics of the structures is also performed, using a consistent set of numerical parameters. The naming scheme can be expanded to carbon systems with mixed hybridizations and to other non-carbon 2D systems. [Display omitted] [ABSTRACT FROM AUTHOR]

In this article, an extended state observer‐based finite‐region control scheme is presented for two‐dimensional Markov jump systems with unknown mismatched disturbances. The mathematical model of the two‐dimensional Markov jump systems is built on the well‐known Roesser model. By establishing special recursive formulas and utilizing the 2‐D Lyapunov function theory, sufficient conditions are obtained, which prove that the resultant system is finite‐region bounded, if some linear matrix inequalities are achieved. Then, we provide an algorithm to solve the extended state observer‐based controller gains. With the proposed control scheme, the external disturbances can be actively rejected from the system outputs. To conclude, a numerical example based on the Darboux equation is provided to demonstrate the validity and effectiveness of the devised control scheme. [ABSTRACT FROM AUTHOR]

BACKGROUND: In domestic and foreign literature, an in vitro model is an important tool to study the pathogenesis and effective treatment of osteoarthritis. All kinds of in vitro models have their advantages and disadvantages and related applications; however, so far, there is no ideal experimental model that can study all the characteristics of osteoarthritis. OBJECTIVE: To review relevant literature in recent years and summarize the advantages and disadvantages of various osteoarthritis models in vitro and their related applications, providing further understanding of osteoarthritis and its therapeutic methods. METHODS: The articles related to PubMed, CNKI, VIP, and WanFang databases from 2010 to 2021 were searched by computer with the English search words: “osteoarthritis, in vitro, model” in English and Chinese. Sixty-three qualified literature with strong correlation and relatively new publication years were selected for review. RESULTS AND CONCLUSION: Two-dimensional cell culture models of osteoarthritis are easy to be constructed and produced on a large scale, but they are only suitable for studies at the cellular level due to the lack of typical three-dimensional microstructure and interactions with surrounding cells and extracellular matrix. Explant model and three-dimensional cell culture provide an internal environment close to the physical condition of the human body, which can be used to study not only cytokines stimulation but also physical injuries and biomechanical changes. Therefore, we can better study the molecular mechanism of osteoarthritis and propose available interventions. However, from the view of tissue volume and cell vitality, mass production of these models is difficult. In addition, the article also discusses advanced tissue engineering models such as three-dimensional biofabrication models, organoids, and organ-on-a-chip models. Three-dimensional bio-printing technologies and bioreactors have obvious advantages in precise control of tissue structure, transport of bioactive molecules, dynamic cell culture and other aspects, but it still needs further improvement and innovation at present. In general, compared with the twodimensional cell culture model, the in vitro three-dimensional tissue model is more suitable for current research and individualized treatment of osteoarthritis. In the future, it is expected to integrate emerging technologies such as organ chip technology, three-dimensional bio-printing technology and bioreactor, and eventually develop a more suitable platform for osteoarthritis treatment and drug testing. [ABSTRACT FROM AUTHOR]

Two-dimensional membranes are considered as the most energy-efficient alternatives to various traditional separation processes. To date, atomically thin hexagonal boron nitride, covalent organic frameworks, graphene, graphene oxide, transition metal carbides and nitrides, layered double hydroxide, transition metal dichalcogenides (TMDCs), and metal-organic frameworks have been extensively investigated for high-performance lamellar membranes, which is due to their tunable physicochemical properties, single-layered structure, and in-plane pore structure. This comprehensive review summarizes the different fabrication methods of TMDC-based membranes and introduces the recent modification strategies to improve their microstructural properties. TMDCs-based membranes for wastewater treatment, desalination, proton exchange, gas separation, and energy devices are extensively discussed. Finally, we highlight the current engineering hurdles and suggest research directions for improving the separation efficiency, stability, and permeability of these membranes. [ABSTRACT FROM AUTHOR]

The checkerboard-like NIDG based on plasma heterostructure shows excellent EWA in the C-band at ultra-low filler loading of 6.2 wt%. [Display omitted] To solve the problem of dispersion of magnetic nanoparticles in ultralight electromagnetic absorption field, checkerboard-like nickel nanoislands/defect graphene aerogel (NIDG) with enhanced surface plasmon resonance was designed and prepared through electrostatic self-assembly method. This special structure successfully overcame the aggregation phenomenon of magnetic metals and built high-density gap regions to enhance surface plasmon resonance. And the NIDG has achieved excellent electromagnetic wave absorption performance in C band. Specially, NIDG is superior in ultra-lightness with only 6.2 wt%, compared to some recently reported magnetic electromagnetic wave absorbers. Such great performance can be attributed to the enhanced surface plasmon resonance and improved impedance matching. This work is significant for achieving effective dielectric loss and designing lightweight low-frequency EMW absorbing materials. [ABSTRACT FROM AUTHOR]

To improve the response-ability of the energy harvester to multidirectional wind, this paper proposes a wind energy harvester to scavenge wind-induced vibration energy. The harvester comprises a cylindrical beam instead of conventional thin rectangular cantilevers, a bluff body (square prism or circle cylinder), and a piezoelectric tube bonded to the bottom side of the beam for energy conversion. Benefiting from the symmetry of the cylindrical structure, this harvester can respond to airflow from every direction of the two-dimensional plane. The performance of the harvester under a wind speed range of 1.5–8 m/s has been tested. The results demonstrate that the proposed harvester can respond to the wind from all directions of the two-dimensional plane. It provides a direction for the future in-depth study of multidirectional wind energy harvesting. [ABSTRACT FROM AUTHOR]

High‐entropy alloys (HEAs) inspire exploration toward vast compositional space, enabled through the mixing of multiple elements for the advent of novel materials. Moreover, the unique blend of multiple elements into an alloy form at nanoscale in various morphologies can offer exceptional functionalities with high stability that can significantly tune the physical and chemical properties of the HEAs. However, the combination of multiple elements and their downsizing to multi‐dimensional complex alloy nanostructures with limitless combinations and compositions remains highly rewarding yet intricate. Several strategies have been introduced and demonstrated to widen the scope of multi‐element alloys as zero‐dimensional (0D), one‐dimensional (1D), two‐dimensional (2D), and three‐dimensional (3D) nanostructures and exemplify their potential as promising materials for various applications. Nevertheless, these are few and insufficient in terms of element combinations, which are mainly limited to noble metals, and dimensionality, mainly as 0D nanoparticles (NPs). This review focuses on key developments and overviews elegant strategies for the development of HEA nanoarchitectures. We predict that these developments will inspire researchers to extend their work, beyond 0D HEA NPs, toward various distinct HEA morphologies with unlimited element combinations, which can provide new avenues for emerging applications and unknown technologies. Finally, we believe that this review can offer future directions and scope for the design and development of new families of HEA nanoarchitectures with vast compositional space in distinct shapes for various unattempted applications using many unexplored methodologies. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) nanomaterials like graphene, layered double hydroxides, etc., have received increasing attention owing to their unique properties imparted by their 2D structure. The newest member in this family is based on metal-organic frameworks (MOFs), which have been long known for their exceptional physicochemical properties—high surface area, tunable pore size, catalytic properties, etc., to list a few. 2D MOFs are promising materials for various applications as they combine the exciting properties of 2D materials and MOFs. Recently, they have been extensively used in biosensors by virtue of their enormous surface area and abundant, accessible active sites. In this review, we provide a synopsis of the recent progress in the field of 2D MOFs for sensor applications. Initially, the properties and synthesis techniques of 2D MOFs are briefly outlined with examples. Further, electrochemical and optical biosensors based on 2D MOFs are summarized, and the associated challenges are outlined. [ABSTRACT FROM AUTHOR]

The work shows a significant effect of the focusing magnetic field on the output characteristics of the klystron. When the calculations are done using nonlinear one-dimensional models, optimization of the parameters makes it possible to obtain versions of devices with the efficiency of 0.8 – 0.9 and higher. However, when testing these options using nonlinear two-dimensional models that take into account the radial motion of electrons, there is a significant discrepancy in the output characteristics obtained from the one-dimensional and two-dimensional models. This is due to the fact that during the motion of the electron beam, the radii of the leading centers of the large particles change the coefficients of interaction of the particle fields with the electromagnetic fields of the resonators change, which leads to a change in the output characteristics of the klystrons: efficiency, output power, and gain. On the other hand, it seemed that setting a large focusing magnetic field to exclude the radial motion of particles could eliminate this drawback, however, another problem arises here - the magnetic system for focusing becomes unacceptably large and it is technically difficult to obtain magnetic induction values of more than 2 T (the weight of the magnetic system can be several hundred kilograms). Therefore, one should choose the magnetic field induction for focusing the electron beam no more than 1T. In this paper, a twodimensional nonlinear mathematical model (2.5D) is proposed that takes into account the azimuthal component in the equations of motion. In the model, the induction of the focusing magnetic field is set in the form of tables. This makes it possible to set the inhomogeneity of the magnetic field at any place in the interaction space of the klystron. The calculation of a powerful relativistic klystron with an accelerating voltage of 1000 kV and the beam current of 250 A was carried out. The use of an inhomogeneous magnetic field makes it possible to reduce the deposition of electrons in the region of the gaps. Therefore, a decrease in the electron deposition leads to an increase in the durability of klystrons.

[Display omitted] • LTV visualized the real-time transport of BCs in the presence of DOM. • Soil DOM facilitates the transport of BCs. • The transport mechanisms of BCs in the presence of DOM are revealed. • Double-Monod model can match BCs transport and retention behavior. Biochar colloids (BCs) have attracted much attention globally, and their fate and transport in the subsurface are significantly influenced by soil-dissolved organic matter (DOM) in soil. This study utilized a real-time and non-invasive visualization system to reveal the transport and retention behavior of BCs in the presence of DOM in two-dimensional porous media. Results indicated that the presence of DOM enhanced the transport of BCs, due to its increased negative charge density and increased repulsion between BCs. The change in the particle size of the porous medium was also shown to affect the BCs transport in the porous media. Additionally, the negative charge of BCs shielded by high IS, the mobility of BCs decreased by 30.37 % from 1 mM to 50 mM. When the pH was increased from 5 to 9, the oxygen-containing functional groups of BCs and DOM were dissociated, and the mobility of BCs increased by 32.41 %. Through a simplified Double-Monod model, we fitted the breakthrough curves for BCs transport in porous media (R2 > 0.94). Moreover, the mechanism of different conditions on colloid clogging behavior was further elucidated through the DLVO theory. These findings extend the understanding of the environmental behavior of BCs in the presence of DOM derived from soil, enabling us to assess better and predict their environmental risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesized a two-dimensional cobalt-based metal-organic framework (MOF) with abundant adsorption sites. • The maximum amount of Cr(VI) adsorbed by 2D-Co-MOF-N in wastewater is 207.93 mg/g, which is larger than most MOFs adsorbents. • The Cl−, NO 3 −, SO 4 2−, and PO 4 3− in the solution inhibited the adsorption of Cr(VI) in wastewater by competitive adsorption. Metal-organic frameworks (MOFs) display multi-level pores and abundant adsorption sites, which can effectively adsorb Cr(VI) from wastewater. In this paper, x-ray single crystal diffraction analysis showed that both the N atom and two carboxyl groups in L2− of [Co(L)(H 2 O) 2 ] n (1) (H 2 L = 3, 5-pyridinedicarboxylic acid) underwent coordination reactions with Co(II) in μ 3 -η1:η1:η1 fashion, giving rise to the formation of a two-dimensional structure. The nano adsorbent of 1 (2D-Co-MOF-N) with a particle diameter about 100 nm was successfully prepared by cell disruption method. The optimal conditions for 2D-Co-MOF-N to adsorb Cr(VI) from wastewater were observed at pH 6.5, T = 30 °C, and a dosage of 0.10 g/L, achieving a maximum adsorption capacity of 207.93 mg/g which was better than most MOFs adsorbents. The present of Cl−, NO 3 –, SO 4 2−, and PO 4 3− in wastewater inhibited the adsorption of Cr(VI) by 2D-Co-MOF-N due to competitive adsorption. Cycling experiments showed that 2D-Co-MOF-N exhibited admirable structural and performance stability, which could be deemed as a potential candidate for the removal toxic ions from actual wastewater. [ABSTRACT FROM AUTHOR]

Current state-of-the-art ultraviolet (UV) photodetectors are extensively used in applications ranging from industrial to biomedical science. As a result, there have been consistent efforts to improve their efficiency and to address challenges related to sensitivity and spectral selectivity. Two-dimensional (2D) materials, with their distinct properties, offer a promising solution due to their excellent UV detection characteristics. Additionally, their atomic scalability and CMOS compatibility enable easy integration with flexible platforms and current technologies. The exceptional optoelectronic characteristics, strong light-matter interaction, and quantum confinement in certain 2D materials have led to extensive investigations into 2D material-based UV photodetectors. This review provides a broad overview of the mechanisms of photodetection, various device configurations, and the current progress in both layered and non-layered 2D UV photodetectors. Finally, strategies for improving UV photodetection properties are discussed, along with a future outlook on the integration of 2D UV detectors into commercial platforms. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous graphene (PG) nanosheets have become one of the superstars in the graphene material family due to their diverse pore structures and unique properties. Their most distinctive features are the pore structures on the basal planes. The presence of in-plane pores affects the inert surface of graphene, increases longitudinal transport channels and more active sites, alleviates lamellar accumulation, and extends the application range of graphene. In order to better study the effect of different pore construction methods on the pore structure, focusing two-dimensional materials, the chemical properties of graphene derivatives and their functional modifications are first reviewed, with an in-depth discussion of the latest techniques for in-plane pore construction. Looking into large-scale preparation of PG and precise control of pore structures and morphologies, a novel bottom-up in-plane pore construction method was proposed for the first time based on directional recombination. Then, recent progress on PG as membrane material for membrane separation, energy storage, and electrocatalysis was analyzed. Finally, based on the existing techniques for pore construction and manipulation as well as future research needs, the knowledge gap and technical challenges yet to overcome are summarized, and solutions were proposed to address the issues. It is helpful to further control the pore structure and develop more accurate pore construction method. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A polypyrrole coating strategy is proposed to mitigate the "under-voltage failure" and enhance the rate capability of sulfide-based electrodes for SIBs. • The holey structure of NiS 2 and the conductive polypyrrole coating boost fast interfacial pseudocapacitive charge storage. • The intermediate polysulfides are efficiently adsorbed by nitrogen atoms on the polypyrrole framework. • NiS 2 @PPy delivers high capacities of 393 and 373 mAh/g at 2.0 and 5.0 A/g over 1700 cycles. The application of transition metal sulfide-based anodes in sodium-ion batteries (SIBs) is held back by the poor rate capability and the knotty shuttle effect of polysulfides. Herein, a facile and scalable polypyrrole coating strategy is proposed to address the aforementioned issues. In-situ polymerization of pyrrole on porous NiS 2 nanoplatelets produces a polypyrrole-coated NiS 2 composite (NiS 2 @PPy). The holey structure of NiS 2 enhances ion transport while increasing contact area with polypyrrole shells. When used as the anode for SIBs, the conductive polypyrrole coating of NiS 2 @PPy can significantly accelerate the electrode kinetics by boosting fast interfacial pseudocapacitive charge storage, which accounts for ∼90 % of total capacity even at a low sweep rate of 0.1 mV s−1. Meanwhile, the conformal coating can accommodate the volume expansion of NiS 2 during cycling, enhancing the long-term durability of NiS 2 @PPy. More importantly, the intermediate polysulfides are efficiently adsorbed by the nitrogen atoms on the polypyrrole framework, thereby alleviating the under-voltage failure caused by the shuttle effect. Consequently, the as-prepared NiS 2 @PPy achieves high capacities of 393 and 373 mAh/g at 2.0 and 5.0 A/g over 1700 cycles. Motivated by the encouraging results in SIBs, we also explored the potentiality of NiS 2 @PPy for the potassium-ion batteries. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) porous semiconductors with rich pores on their surface have presented great potential in photocatalysis fields by fantastic structural merits. In comparison to the bulk photocatalysts, the 2D porous semiconductor photocatalysts display several obvious merits including a shortened charge shift route, facilitated mass transportation channels, abundant surface active centers, and improved light harvesting capability. Up to now, a variety of experimental strategies have been explored for the synthesis of 2D porous photocatalysts, with improved photocatalytic activity for various reactions being achieved. In this mini-review, the recent advances in advanced 2D porous semiconductors for efficient photocatalytic clean energy evolution were critically reviewed. Meanwhile, the synthesis methods and the fundamental mechanism of 2D porous photocatalysts in various photocatalytic reactions were emphasized. In particular, the effects of the structural, morphology, electronic structure, and charge carrier migration advantages on the facilitated photocatalytic process were highlighted. Finally, the prospects and challenges of 2D porous photocatalysts for large-scale industrial utilization were overlooked and discussed. We cordially look forward to this critical review can offer a snapshot of advanced 2D porous photocatalysts for improved solar light energy conversion and inspire several new concepts for designing high-performance photocatalysts. [Display omitted] • The advantages of 2D porous photocatalysts in clean energy production are elaborated. • The synthesis methods and basic mechanisms of 2D porous photocatalysts are introduced. • The several kinds of 2D porous photocatalysts and their structure and composition merits are presented. • The prospects and challenges of large-scale industrial applications were discussed. [ABSTRACT FROM AUTHOR]

The inverse finite element method (iFEM) is a powerful tool for shape sensing and structural health monitoring and has several advantages with respect to some other existing approaches. In this study, a two-dimensional eight-node quadrilateral inverse finite element formulation is presented. The element is suitable for thin structures under in-plane loading conditions. To validate the accuracy and demonstrate the capability of the inverse element, four different numerical cases are considered for different loading and boundary conditions. iFEM analysis results are compared with regular finite element analysis results as the reference solution and very good agreement is observed between the two solutions, demonstrating the capability of the iFEM approach.

The monitoring of crop phenology informs decisions in environmental and agricultural management at both global and farm scales. Current methodologies for crop monitoring using remote sensing data track crop growth stages over time based on single, scalar vegetative indices (e.g., NDVI). Crop growth and senescence are indistinguishable when using scalar indices without additional information (e.g., planting date). By using a pair of normalized difference (ND) metrics derived from hyperspectral data—one primarily sensitive to chlorophyll concentration and the other primarily sensitive to water content—it is possible to track crop characteristics based on the spectral changes only. In a two-dimensional plot of the metrics (ND-space), bare soil, full canopy, and senesced vegetation data all plot in separate, distinct locations regardless of the year. The path traced in the ND-space over the growing season repeats from year to year, with variations that can be related to weather patterns. Senescence follows a return path that is distinct from the growth path.

As a unique two-dimensional (2D) material, 2D noble metal-based intermetallic compounds (IMCs) have attracted much attention in electrocatalysis owing to their exceptional physical and chemical properties. However, the synthesis of 2D noble metal-based IMCs with well-defined structures remains challenging. This comprehensive review begins by delving into the morphology modulation of 2D noble metal-based IMCs, highlighting their key synthesis strategies, such as the CO-assisted and halide ion modulation methods. Subsequently, we discuss the advantages of 2D noble metal-based IMCs in electrocatalysis, including oxygen reduction reaction, alcohol oxidation reaction, formic acid oxidation reaction, and hydrogen evolution reaction. Finally, the main challenges and perspectives for the future development of 2D noble metal-based IMC electrocatalysts are presented to accelerate their promising commercialization.

Abstract Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets (e.g., MoS2) with metallic phase (1T or 1T´ phase) have been proven to exhibit superior performances in various applications as compared to their semiconducting 2H-phase counterparts. However, it remains unclear how the crystal phase of 2D TMD nanosheets affects their sonodynamic property. In this work, we report the preparation of MoS2 nanosheets with different phases (metallic 1T/1T´ or semiconducting 2H) and exploration of its crystal-phase effect on photothermal-enhanced sonodynamic antibacterial therapy. Interestingly, the defective 2D MoS2 nanosheets with high-percentage metallic 1T/1T´ phase (denoted as M-MoS2) present much higher activity towards the ultrasound-induced generation of reactive oxygen species (ROS) as compared to the semiconducting 2H-phase MoS2 nanosheets. More interestingly, owing to its metallic phase-enabled strong absorption in the near-infrared-II (NIR-II) regime, the ultrasound-induced ROS generation performance of the M-MoS2 nanosheets can be further enhanced by the photothermal effect under a 1064 nm laser irradiation. Thus, after modifying with polyvinylpyrrolidone, the M-MoS2 nanosheets can be used as an efficient sonosensitizer for photothermal-enhanced sonodynamic bacterial elimination under ultrasound treatment combining with NIR-II laser irradiation. This study demonstrates that metallic MoS2 nanosheets can be used as a promising sonosensitizer for antibacterial therapy, which might be also promising for cancer therapies. Graphical Abstract

Aim This study compared the effectiveness of the three-dimensional (3D) cone beam computed tomography (CBCT) method of age estimation developed by Asif et al. with two-dimensional Cameriere’s method. Subjects and methods CBCT images belonging to 129 Malaysian Chinese and Malay ethnic groups aged 7–14 years were investigated and analysed. Results The results indicated a strong correlation between chronological age and the predictor variables for both Cameriere’s (r = 0.984) and Asif’s (r = 0.988) methods of age estimation. Fisher Z test analysis indicated no statistically significant difference in the correlation values between the two methods. Mean absolute error (MAE) value of 0.613 was observed for Cameriere’s and 0.290 was observed for Asif’s method. Conclusions The results indicated that the methods of age estimation from both Asif et al. and Cameriere et al. are applicable on Malaysian children. However, Asif et al.’s 3D CBCT method of age estimation resulted in greater accuracy and reliability in estimating chronological age.

Highlights 1. Adequate feasibility of 3D STE in pediatrics; comparable to 2D STE. 2. Significantly shorter acquisition and analysis time for 3D GLS compared to 2D GLS. 3. Excellent agreement between 3D and 2D LV GLS and moderate to poor agreement between regional strain values. 4. Excellent inter and intra-observer reproducibility for GLS by the two techniques, and fair to poor reproducibility for regional strain (higher for apical than basal regions).

Abstract Two‐dimensional (2D) MXene‐based nanofiltration membranes could sustainably and rapidly produce clean water. However, the challenges related to the severe swelling of the MXene membranes in water should be overcome before the practical application. In this work, the negatively charged MXene‐based membrane is modified by positively charged polyethyleneimine (PEI) with various PEI:MXene ratios. The PEI‐MXene is deposited on a polyacrylonitrile (PAN) substrate as a top membrane to prepare an anti‐swelling composite PEI‐MXene/PAN membranes with outstanding mechanical strength and stability. Interestingly, when the interlayer spacing of the top Mxene layers are tuned between ca. 14.15 and ca. 14.52 Å, the resultant PEI‐MXene/PAN membranes exhibit the excellent ability of size sieving. For instance, PEI‐MXene(1:1)/PAN membrane presents high flux performance to Acid Blue 90 (AB90), Congo Red (CR), and Direct Red 80 (DR80) (i.e., 563.9, 882.6, and 633.6 L m−2 h−1, respectively) at 0.2 MPa, and remarkable rejection rates, that is, 99.3%, 99.82%, and 99.9%, respectively. Besides, the PEI‐MXene(0.5:1)/PAN possesses the highest flux of 1528.1 L m−2 h−1 and outstanding rejection rate of 99.9% to dye of AB8GX. Moreover, the proposed strategy can be extended to the modification of other 2D material nanofiltration membranes.

Pathogenic microbial infections have been threatening public health all over the world, which makes it highly desirable to develop an antibiotics-free material for bacterial infection. In this paper, molybdenum disulfide (MoS2) nanosheets loaded with silver nanoparticles (Ag NPs) were constructed to inactive bacteria rapidly and efficiently in a short period under a near infrared (NIR) laser (660 nm) in the presence of H2O2. The designed material presented favorable features of peroxidase-like ability and photodynamic property, which endowed it with fascinating antimicrobial capacity. Compared with free MoS2 nanosheets, the MoS2/Ag nanosheets (denoted as MoS2/Ag NSs) exhibited better antibacterial performance against Staphylococcus aureus by the generated reactive oxygen species (ROS) from both peroxidase-like catalysis and photodynamic, and the antibacterial efficiency of MoS2/Ag NSs could be further improved by increasing the amount of Ag. Results from cell culture tests proved that MoS2/Ag3 nanosheets had a negligible impact on cell growth. This work provided new insight into a promising method for eliminating bacteria without using antibiotics, and could serve as a candidate strategy for efficient disinfection to treat other bacterial infections.

Rational design and preparation of multifunctional low dimensional nanomaterials are of great importance for in vivo imaging and safety therapy. Meanwhile, nanomaterials with good bio-compatible and effectively photothermal conversion are still demanded to be fabricated in biomedicine. In this work, we have developed two-dimensional bismuth selenide nanosheets as the imaging and photothermal nanoagents. Through doping engineering, the near infrared photothermal conversion of Nd doped nanosheets was boosted by 52 %, which is higher than many previous works. Besides, the prepared nanomaterials can realize infrared and in vivo computed X-ray tomography bioimaging, due to the rich optical-magnetic properties of Nd atoms. The in vitro and vivo experiments with mice display that the Nd doped nanosheets have low toxicity and high biocompatibility. More importantly, the nanomaterials can efficiently achieve photothermal tumor ablation. It is suggested that designed and developed nanosheets have promising applications for biomedicine.

The c-MYC (MYC) oncoprotein is deregulated in over 50% of cancers, yet regulatory mechanisms controlling MYC remain unclear. To this end, we interrogated the MYC interactome using BioID mass spectrometry (MS) and identified PP1 (protein phosphatase 1) and its regulatory subunit PNUTS (protein phosphatase-1 nuclear-targeting subunit) as MYC interactors. We demonstrate that endogenous MYC and PNUTS interact across multiple cell types and that they co-occupy MYC target gene promoters. Inhibiting PP1 by RNAi or pharmacological inhibition results in MYC hyperphosphorylation at multiple serine and threonine residues, leading to a decrease in MYC protein levels due to proteasomal degradation through the canonical SCFFBXW7 pathway. MYC hyperphosphorylation can be rescued specifically with exogenous PP1, but not other phosphatases. Hyperphosphorylated MYC retained interaction with its transcriptional partner MAX, but binding to chromatin is significantly compromised. Our work demonstrates that PP1/PNUTS stabilizes chromatin-bound MYC in proliferating cells.

We use simple acid-base chemistry to control the valency in self-assembled monolayers of two different carboranedithiol isomers on Au{111}. Monolayer formation proceeds via Au-S bonding, where manipulation of pH prior to or during deposition enables the assembly of dithiolate species, monothiol/monothiolate species, or combination. Scanning tunneling microscopy (STM) images identify two distinct binding modes in each unmodified monolayer, where simultaneous spectroscopic imaging confirms different dipole offsets for each binding mode. Density functional theory calculations and STM image simulations yield detailed understanding of molecular chemisorption modes and their relation with the STM images, including inverted contrast with respect to the geometric differences found for one isomer. Deposition conditions are modified with controlled equivalents of either acid or base, where the coordination of the molecules in the monolayers is controlled by protonating or deprotonating the second thiol/thiolate on each molecule. This control can be exercised during deposition to change the valency of the molecules in the monolayers, a process that we affectionately refer to as the "can-can." This control enables us to vary the density of molecule-substrate bonds by a factor of 2 without changing the molecular density of the monolayer.

Compressive beamforming with a planar microphone array can effectively estimate the two-dimensional directions-of-arrival and quantify the strengths of acoustic sources. Due to the superiorities of overcoming the basis mismatch issue of the conventional grid-based method and improving the performance of the single-snapshot grid-free method, the multiple-snapshot grid-free method has become the current research focus. Its existing atomic norm minimization (ANM) based strategy blocks high resolution because it cannot work well for sources with a small separation. This paper commits itself to remedying this drawback. After revealing the cause for this drawback, we present an iterative reweighted ANM (IRANM) approach. Both simulations and experiments demonstrate that compared with the ANM-based two-dimensional multiple-snapshot grid-free compressive beamforming, the IRANM-based one enjoys not only the enhanced resolution but also the stronger denoising ability and the higher identification accuracy. [ABSTRACT FROM AUTHOR]

Compared with three-dimensional bulk MFI zeolites, two-dimensional MFI zeolites have larger surface areas, shorter diffusion distances, and more flexible structures, and they have greater advantages in catalysis. In the synthesis of two-dimensional MFI zeolites, bi-functional templates with hydrophilic and hydrophobic groups play an important role. Templates with different groups and different chain lengths have important effects on the morphologies and catalytic performances of synthesized two-dimensional zeolites. In this study, based on the research status of two-dimensional MFI zeolites in recent years, the synthesis methods, structural modification and cost reduction of layered MFI zeolites are introduced. The advantages and disadvantages of the different synthesis methods are discussed, and the opportunities and challenges in the future are presented. [ABSTRACT FROM AUTHOR]

Monodispersed silica (SiO2) nano- and microparticles can be fabricated by the sol-gel process. For device fabrication, precise formation of composite particles with a homogeneous and facile arrangement that form well-ordered, close-packed arrays is important. In this study, formation of electrostatically assembled SiO2–SiO2 composite particles with excellent homogeneity in arrangement was first demonstrated using sol-gel-derived monodispersed SiO2 particles with average particles sizes of 200 nm and 16 µm. Formation of two- and three-dimensionally, close-packed arrays by electrophoresis-induced stimulation with direct-current and alternating-current electric fields was achieved for the first time using these electrostatically assembled SiO2–SiO2 composite particles. Detailed morphological observation by scanning electron microscopy revealed that the structure of the SiO2–SiO2 composite particles remained intact even after electrophoretic stimulation. The feasibility of obtaining well-ordered arrays of electrostatically assembled sol–gel-derived SiO2–SiO2 composite particles is important for further development of sol-gel-related technology in various applications, such as advanced composites and optical devices. Highlights: Electrostatically assembled SiO2–SiO2 composite particles were prepared using monodispersed sol–gel-derived SiO2 particles with two sizes. Ordered two- and three-dimensional SiO2–SiO2 composite-particle arrangements were obtained. Superimposition of AC and DC electric fields through electrophoresis-induced stimulation generated a two-dimensional close-packed structure. Simultaneous gravitational sedimentation and AC field application led to formation of three-dimensionally ordered arrays. [ABSTRACT FROM AUTHOR]

Manganese sulfides (MnS) are particularly appealing electrode candidates for lithium/sodium‐ion batteries, because of their low cost, wide availability, and environmental benignity. Herein, well‐defined Mn(OH)(OCH3) nanoflakes are synthesized for the first time, whereby two‐dimensional (2D) porous α‐MnS and its composite with N, S co‐doped carbon (α‐MnS@NSC) are produced via the topologic sulfurization of Mn(OH)(OCH3) or a Mn(OH)(OCH3)@polydopamine intermediate. The electrochemical lithium/sodium‐storage properties of α‐MnS are most likely governed by the conductivity, and thus can be significantly enhanced through integrating with conductive carbon coating. As a result, α‐MnS@NSC outperforms the bare α‐MnS and most of the reported MnS‐based anodes, demonstrating the high reversible capacities (1275 mA h g−1 at 0.2 A g−1 for LIBs and 581 mA h g−1 at 0.1 A g−1 for SIBs), great rate capability, and long cyclabilities. This work showcases both a novel strategy to fabricate 2D manganese‐based compounds and a preferred architecture for high performance lithium/sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

The current study is attempted to explore the general solution for the plane problem of an orthotropic hygro-electro-magneto-thermoelastic material (HEMTM). A complete general solution is accomplished by the aid of operator theory and superposition principle, which satisfies twelfth order partial differential equation. Moreover, the obtained general solution is simplified in terms of six harmonic functions and is helpful for boundary value problem of HEMTM. As an application, the fundamental solution for a steady point moisture source combined with heat source in an infinite HEMTM is derived using the general solution. Consequently, exact and complete solutions in terms of elementary functions are obtained, which can serve as a benchmark for various kinds of numerical codes and approximate solutions. Along with this, numerical simulations are conducted using the general solution and graphically illustrated. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals (vdW) materials have extraordinary thermal properties due to the effect of quantum confinement, making them promising for thermoelectric energy conversion and thermal management in microelectronic devices. In this review, the mechanism of phonon anharmonicity originating from three- and four-phonon interactions is derived. The phonon anharmonicity of 2D vdW materials, involving the Grüneisen parameter, phonon lifetime, and thermal conductivity, is summarized and derived in detail. The size-dependent thermal conductivity of representative 2D vdW materials is discussed experimentally and theoretically. This review will present fundamental and advanced knowledge on how to evaluate the phonon anharmonicity in 2D vdW materials, which will aid the design of new structures and materials for applications related to energy transfer and conversion. [ABSTRACT FROM AUTHOR]