Carrier Properties Research Articles

МОДЕЛИРОВАНИЕ ПРОЦЕССОВ ТЕПЛОМАССООБМЕНА В РЕКУПЕРАТОРЕ ТИПА «ТРУБА В ТРУБЕ»

Recuperators including heat exchangers of various types are considered. The prospects of using pipe-in-pipe heat exchangers for the utilization of thermal emissions containing significant amounts of moisture and gas emissions, for example, ammonia, which is typical for livestock complexes, are shown. When heat carriers come into contact with different temperatures, moisture vapors condense on the walls of the heat exchanger and gaseous ammonia dissolves in it. The removed air is supplied to the inner pipe, condensate in the form of ammonia water is removed at the bottom of the installation, and the cooled and purified air is discharged through the upper branch pipe into the atmosphere. Based on the theory of similarity, a model setup has been developed. With the help of the SolidWorks Flow Simulation software package, the influence of hydrodynamic and thermophysical properties of heat carriers on heat and mass transfer processes was studied. The temperatures of the cold coolant ranged from -5 to -23 ° C, (outside air), the temperature of the thermal coolant (exhaust air) is +25 ° C. It was found that in order to avoid freezing of the inner surface of the heat exchanger, the temperature of the air supplied to the outer pipeline should be above -10 ° C. To increase the heat transfer coefficient, it is advisable to supply heat carriers tangentially. At the same time, it is desirable to maintain the same coolant velocities in the supply and exhaust connection pipes of the installation. To increase the energy efficiency of the installation, it is recommended to develop and improve methods for turbulizing coolant flows.

Minimizing Interfacial Recombination in 1.8eVTriple-Halide Perovskites for 27.5% Efficient All-Perovskite Tandems.

All-perovskite tandem solar cells show great potential to enable the highest performance at reasonable costs for a viable market entry in the near future. In particular, wide-bandgap (WBG) perovskites with higher open-circuit voltage (VOC ) are essential to further improve the tandem solar cells' performance. Here, a new 1.8eV bandgap triple-halide perovskite composition in conjunction with a piperazinium iodide (PI) surface treatment is developed. With structural analysis, it is found that the PI modifies the surface through a reduction of excess lead iodide in the perovskite and additionally penetrates the bulk. Constant light-induced magneto-transport measurements are applied to separately resolve charge carrier properties of electrons and holes. These measurements reveal a reduced deep trap state density, and improved steady-state carrier lifetime (factor 2.6) and diffusion lengths (factor 1.6). As a result, WBG PSCs achieve 1.36V VOC , reaching 90% of the radiative limit. Combined with a 1.26eV narrow bandgap (NBG) perovskite with a rubidium iodide additive, this enables a tandem cell with a certified scan efficiency of 27.5%.

Charge Carriers Localization Effect Revealed through Terahertz Spectroscopy of MXene: Ti3C2Tx.

The transport properties of charge carriers in MXene, a promising material, have been studied using terahertz time-domain spectroscopy (THz-TDS) to examine its potential applications in optical and electronic devices. However, previous studies have been limited by narrow frequency ranges, which have hindered the understanding of the intrinsic mechanisms of carrier transport in MXenes. To address this issue, ultrabroadband THz-TDS with frequencies of up to 15 THz to investigate the complex photoconductances of MXene (Ti3C2Tx) films with different thicknesses are employed. The findings indicate that the electronic localization is substrate-dependent, and this effect decreases with an increase in the number of layers. This is attributed to the screening effect of the high carrier density in Ti3C2Tx. Additionally, the layer-independent photocarrier relaxations revealed by optical pump THz probe spectroscopy (OPTP) provide evidence of the carrier heating-induced screening effect. These results are significant for practical applications in both scientific research and various industries.

Determination of the main technological parameters of cyclic-steam stimulation of oil reservoirs with account of heat losses along the borehole

Due to the decline in light oil reserves, the development of high-viscosity oil fields has become more relevant today. One of the most common methods of thermal enhanced oil recovery is cyclic-steam stimulation. Compared to other techniques, this method has an advantage of providing higher thermal efficiency due to selection of its parameters with account of variations in the basic properties of a heat carrier as it moves towards the well bottom. The purpose of this work is to create a method for rapid assessment of optimal technological parameters of cyclic-steam stimulation, in which the temperature distributions along boreholes obtained from geophysical research are used as initial data. The created method allows determination of the time of hot carrier injection, steam soak and oil production. The scientific novelty of the study refers to the fact that an integrated approach relating the problem of hot carrier transportation with the problem of determination of optimal parameters for reservoir treatment is proposed for the first time. The cyclic-steam stimulation process is described by the equations of mechanics of multiphase systems. Euler’s method is used to solve the resulting system of equations. The paper presents: functions of depth-wise distributions of pressure, temperature and velocity and dryness fraction of steam; temperature distribution in the multilayer wall of the well and in the rock (considering a specified heat transfer between the layers of the well materials, water and rock at known temperatures); optimal values of the time of hot carrier injection, steam soak and oil production. The calculations have shown that, due to the in the layer of basalt fiber, the temperature in the multilayer wall of the well decreases within 80%. The maximum value of additional cumulative oil recovery has been established by analyzing the calculated bottom-hole parameters of the heat carrier.

Effect of Weathering on Steel Converter Slag Used as an Oxygen Carrier.

Steel converter slag, also called LD slag, is a material that has been suggested for use as a low-cost oxygen carrier for chemical looping applications. Low-cost oxygen carriers are especially relevant for the conversion of solid fuels, which may contain large amounts of reactive ashes. Ash may limit the lifetime of the bed material, which is why a high-cost oxygen carrier will likely not be competitive. Applying LD slag on an industrial scale as an oxygen carrier makes the storage properties of the material highly interesting. LD slag has been known to be affected by weathering, thus limiting the possibilities of the material to be used in construction, e.g., as fillers in concrete. In this study, pretreated LD slag for use as an oxygen carrier was weathered outdoors for roughly 1.5 years in southwest Sweden. Afterward, the particles were characterized and used in a laboratory batch fluidized bed reactor system to evaluate the effects of storage on the oxygen carrier properties. It was found that the reactivity with the fuel of the weathered LD slag was similar to that of the original sample when used in a laboratory fluidized bed. However, the physical properties were severely degraded due to weathering. Dissolved CaO formed CaCO3, agglomerating the top layer of the sample. The particles in the bulk of the sample were found to have decreased density and increased attrition rate. This suggests that LD slag particles for use as oxygen carriers should be stored dry to avoid weathering of the particles.

Monolayer graphene on submicron LiNbO[formula omitted] thin film waveguide: Carrier properties and their effect on waveguide transmission

Photonic devices are currently advancing towards high integration and miniaturization, necessitating the utilization of low-dimensional materials as pivotal components for the next generation of optoelectronic modulators. In this work, we conduct an in-depth exploration of the waveguide properties of submicron ferroelectric material LiNbO3 when integrated with graphene, utilizing a prism-coupled total reflection system. Our experimental findings underscore the significant enhancements in effective index and coupling efficiency upon graphene coverage, and the calculations exhibit the accumulate of electrons in graphene surface. Such distribution of charge and the spontaneous polarization of LiNbO3 itself not only endows graphene with n-type doping characteristics, but also optimizes the overall waveguide performance. Concurrently, the waveguide transmission stability under visible light is verified. The pronounced modifications in effective index and coupling efficiency demonstrate the feasibility of graphene as an electrode, thereby laying the foundation for future investigations into high-speed optical modulators based on the graphene-LiNbO3 platform.

Elasticity, an often-overseen parameter in the development of nanoscale drug delivery systems.

Nanoparticles have shown an enormous potential as drug delivery systems in the lab. However, translation to the clinics or even market approval often fails. So far, the reason for this discrepancy is manifold. Physicochemical properties such as size, surface potential, and surface chemistry are in focus of research for many years. Other equally important parameters, influencing whether a successful drug delivery can be achieved, are mechanical properties of nanoparticles. Even though this is often not even considered during formulation development, and it is not requested for approval, an increasing number of studies show that it is important to have knowledge about these characteristics. In this article, we discuss examples highlighting the influence of elasticity in nanoscale biological interactions focusing on mucosal delivery and on tumor targeting. Besides this, we discuss the influence of different measurement settings using atomic force microscopy for the determination of mechanical properties of drug carriers.

High-throughput screening of suitable nitrogen carriers for chemical looping ammonia synthesis

Chemical looping ammonia synthesis is a promising pathway to synthesise ammonia with lower energy and economic costs than the current Haber-Bosch process, for example, by lowering the operating temperature and/or pressure, whilst maintaining comparable NH3 yield. A solid nitrogen carrier is used to mediate the reaction and form ammonia in consecutive steps. In contrast to the Haber-Bosch process, the thermodynamics and kinetics of the reaction are dependent on the properties of the nitrogen carrier. This introduces additional opportunities for novel designs, though finding suitable materials becomes the challenge. Herein, nitrides from the Materials Project database are screened based on their equilibrium nitrogen pressures and nitrogen exchange capacities. The equilibrium nitrogen pressure was used as a proxy to determine the equilibrium ammonia mole fraction of the reaction, a key performance indicator for chemical looping ammonia synthesis. Using high-throughput gas-solid equilibrium calculations, 2515 nitrides were screened, and 111 nitrides were found to achieve sufficiently high ammonia mole fraction at equilibrium to compete with the Haber-Bosch process. Due to large inaccuracies associated with theoretical material properties, the viability of screened candidates cannot be adequately ascertained. The quality and quantity of theoretical and experimental data for nitrogen carriers, respectively, must be improved further to identify suitable materials for chemical looping ammonia synthesis.

High sensitivity of semimetal photodetection via Bose–Einstein condensation

AbstractThe discovery of semiconductor has witnessed remarkable strides toward high performance of photodetectors attributed to its excellent carrier properties. However, semimetal, owning to the high carrier concentration and low carrier mobility compared to those of semiconductor, is generally considered unsuitable for photodetection. Herein, we demonstrate an outstanding photodetection in a layered semimetal titanium diselenide (TiSe2) in Bose–Einstein condensation (BEC) state. High sensitivity of semimetal photodetector is realized in the range of visible, infrared and terahertz bands. The noise equivalent power (NEP) has threefold improvement at the visible and infrared wavebands, and significant decrease by one order of magnitude in the terahertz frequencies via BEC phenomenon, attributed to the electrical parameter variation after condensation. The best NEP value in the terahertz frequency is comparable to that of commercial Si photodetector. Our results show another recipe to fabricate high performance of photodetection via semimetal except for semiconductor and pave the way to exploit macroscopic quantum phenomena for optoelectronics.image

Room temperature two-dimensional electron gas scattering time, effective mass, and mobility parameters in AlxGa1−xN/GaN heterostructures (0.07 ≤ x ≤ 0.42)

AlxGa1−xN/GaN high-electron-mobility transistor (HEMT) structures are key components in electronic devices operating at gigahertz or higher frequencies. In order to optimize such HEMT structures, understanding their electronic response at high frequencies and room temperature is required. Here, we present a study of the room temperature free charge carrier properties of the two-dimensional electron gas (2DEG) in HEMT structures with varying Al content in the AlxGa1−xN barrier layers between x=0.07 and x=0.42. We discuss and compare 2DEG sheet density, mobility, effective mass, sheet resistance, and scattering times, which are determined by theoretical calculations, contactless Hall effect, capacitance-voltage, Eddy current, and cavity-enhanced terahertz optical Hall effect (THz-OHE) measurements using a low-field permanent magnet (0.6 T). From our THz-OHE results, we observe that the measured mobility reduction from x=0.13 to x=0.42 is driven by the decrease in 2DEG scattering time, and not the change in effective mass. For x<0.42, the 2DEG effective mass is found to be larger than for electrons in bulk GaN, which in turn, contributes to a decrease in the principally achievable mobility. From our theoretical calculations, we find that values close to 0.3m0 can be explained by the combined effects of conduction band nonparabolicity, polarons, and hybridization of the electron wavefunction through penetration into the barrier layer.

Caffeine additive based nanoarchitectonics of methylammonium lead iodide (MAPbI3) perovskite solar cell device: investigations on charge carrier properties using AC impedance spectroscopy

Caffeine additive based nanoarchitectonics of methylammonium lead iodide (MAPbI3) perovskite solar cell device: investigations on charge carrier properties using AC impedance spectroscopy

Higher manganese silicides: A Nowotny chimney ladder phase for thermoelectric applications

Nowotny chimney ladder (NCL) phases are intermetallic binary compounds that typically crystallize in a tetragonal crystal structure and constitute of two separate subsystems. The rich solid-state chemistry of NCL phases inherits fascinating lattice dynamics with unique abilities for structural modifications. As an extensively studied energy material for the thermoelectric application, we overview the emerging aspects for structural interpretation in higher manganese silicides (MnSiγ), a prominently explored example of NCL phase. The progress in understanding the incommensurate composite crystals of MnSiγ is discussed to highlight its functional crystallography for proposing the effective strategies to attain favorable modification of transport properties of charge carriers (concentration, mobility, effective mass), and phonons (lattice thermal conductivity). The application potential and prospective strategies for enabling the rational optimization of the dimensionless thermoelectric figure of merit (zT) are examined, and the possibilities of chemical modification in MnSiγ and related NCL phases are presented.

The Spacer Cation with Disulfide Bond for Efficient and Stable Low‐Dimensional Dion–Jacobson Perovskite Solar Cells

AbstractLow‐dimensional (LD) perovskite has provided an exciting avenue for exploring stable perovskite solar cells (PSCs). However, PSCs based on LD perovskites still suffer from poor efficiency owing to unfavorable charge carrier dynamics. Here, cystamine (CYS) is employed as a ligand to construct LD Dion‐Jacobson (LDDJ) perovskite (CYS)MAn‐1PbnI3n+1 (n = 1, 2, 3…, MA: methylamine) for improving carrier properties. The disulfide bond not only changes the polarization characteristic but also increases the coupling between inorganic slabs due to the low barrier of rotation around the S‐S axis, thus reducing the exciton binding energy of CYS‐based LDDJ perovskite. Disulfide bonds provide a scene for charge localization in the interlayer region, which is conducive to reducing the anisotropy of charge transfer. Thanks to these merits, the (CYS)MA4Pb5I16 film delivers improved carrier diffusion length (electron for 1345 nm and hole for 950 nm) and mobility (9.23 cm2 V−1 S−1). As a result, the (CYS)(MA)4Pb5I16 PSC achieves a champion power conversion efficiency (PCE) of 16.52%, which is much higher than that of HDA and BA cations‐based PSCs (HDA: 1,6‐Hexanediamine, BA: Butylamine). Furthermore, the state‐of‐the‐art device only lost 8% of its initial PCE after 1600 h in the atmosphere.

Optimization of NaBiS2 nanoribbons for photocatalytic application

In this era of technological transformation, while technological advancements have certainly streamlined everyday tasks, they've also ushered in new challenges and threats to human well-being. The contamination of freshwater sources by waste and inadequate sanitation practices has led to a surge in diseases. Photocatalytic treatment has emerged as an effective solution, particularly for addressing emerging contaminants like dissolved organic compounds. We synthesized NaBiS2 using a straightforward coprecipitation method, yielding an orthorhombic crystal phase and nanoribbon morphology. Our analysis of its bonding structure through FTIR spectroscopy revealed the absence of binary functional groups. Notably, NaBiS2 possesses a bandgap of 1.56 eV, placing it within the visible spectrum. Hall measurements provided insights into its charge carrier properties, with holes being the dominant carriers, characterized by high mobility and concentration. When subjected to methylene blue, NaBiS2 exhibited exceptional degradation efficiency. The optimal composition, NBS-4, achieved an impressive 90 % degradation in just 15 min, with complete degradation achieved within 45 min. These findings underscore the significance of NaBiS2 in the realm of photovoltaics and suggest its potential advantages in related applications.

Influence of drug molecular weight on self-assembly and intestinal permeation of polymer-based nanocarriers

For oral delivery, the physicochemical properties of nanocarriers are decisive factors for permeation through the intestinal epithelium. These properties are determined by the composition of the nanocarriers as well as by the process parameters during their self-assembly. For macromolecular drugs, there is still little understanding of the drug-polymer interactions during nanocarrier self-assembly and the effects on carrier properties. In this study, the effect of drug molecular weight on nanocarrier self-assembly, physicochemical properties of nanocarriers as well as their permeation across the intestinal epithelium was investigated. Our results show that the drug molecular weight impacts the physicochemical properties of nanocarriers. Further, the physicochemical properties of the nanocarriers, governed by the molecular weight of the drug, determine their permeation properties across the intestinal epithelium. Comparative in vitro and ex vivo studies revealed that intestinal absorption is dependent on both, the properties of the tissue as well as properties of the carrier system. In conclusion, the molecular weight of drug payload is a key factor determining the physiochemical properties of polymeric nanocarriers and is closely linked to their oral absorption. Using different preclinical models to evaluate intestinal permeation of nanocarriers allows for novel insights into key formulation properties governing oral bioavailability.

Intervertebral disc generation tissue engineering treatment platform: gelatin-methacryloyl hydrogel composite system.

Intervertebral disc generation tissue engineering treatment platform: gelatin-methacryloyl hydrogel composite system.

Effect of Digestion on Ursolic Acid Self-Stabilized Water-in-Oil Emulsion: Role of Bile Salts.

Exploring the effect of bile salts on the properties of emulsion carriers containing hydrophobic bioactive compounds is particularly critical to understanding the stability and bioavailability of these hydrophobic bioactive compounds in the digestive process. In this study, the effects of bile salts on the stability and digestive characteristics of the ursolic acid (UA) self-stabilized water-in-oil (W/O) emulsion were investigated via static and dynamic (with or without enzyme) in vitro simulated digestive systems. The results showed that under the static system, the basic conditions had less interference, while the bile salts had a significant effect on the appearance and microstructure of the emulsion. The primary mechanism of emulsion instability is hydrophobic binding and depletion flocculation. Under the dynamic condition, it was found that the low concentrations of bile salts can promote the release amount and the rate of free fatty acids via displacement, while high concentrations of bile salts inhibit the decomposition of lipid, which may be related to the secondary coverage formed at the interface by the bile salts. These findings provide a theoretical basis for understanding the digestive behavior of the UA emulsion and its interaction with bile salts, which are conducive to developing and designing new emulsions to improve the bioaccessibility of UA.

Lipid carriers for mRNA delivery.

Messenger RNA (mRNA) is the template for protein biosynthesis and is emerging as an essential active molecule to combat various diseases, including viral infection and cancer. Especially, mRNA-based vaccines, as a new type of vaccine, have played a leading role in fighting against the current global pandemic of COVID-19. However, the inherent drawbacks, including large size, negative charge, and instability, hinder its use as a therapeutic agent. Lipid carriers are distinguishable and promising vehicles for mRNA delivery, owning the capacity to encapsulate and deliver negatively charged drugs to the targeted tissues and release cargoes at the desired time. Here, we first summarized the structure and properties of different lipid carriers, such as liposomes, liposome-like nanoparticles, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, nanoemulsions, exosomes and lipoprotein particles, and their applications in delivering mRNA. Then, the development of lipid-based formulations as vaccine delivery systems was discussed and highlighted. Recent advancements in the mRNA vaccine of COVID-19 were emphasized. Finally, we described our future vision and perspectives in this field.

Screening and promoting effect of grow-promoting fungi in rhizosphere of Angelica dahurica var. formosana

Excessive application of chemical fertilizer has caused many problems in Angelica dahurica var. formosana planting, such as yield decline and quality degradation. In order to promote the green cultivation mode of A. dahurica var. formosana and explore rhizosphere fungus resources, the rhizosphere fungi with nitrogen fixation, phosphorus solubilization, potassium solubilization, iron-producing carrier, and IAA-producing properties were isolated and screened in the rhizosphere of A. dahurica var. formosana from the genuine and non-genuine areas, respectively. The strains were identified comprehensively in light of the morphological characteristics and ITS rDNA sequences, and the growth-promoting effect of the screened strains was verified by pot experiment. The results showed that 37 strains of growth-promoting fungi were isolated and screened from the rhizosphere of A. dahurica var. formosana, mostly belonging to Fusarium. The cultured rhizosphere growth-promoting fungi of A. dahurica var. formosana were more abundant and diverse in the genuine producing areas than in the non-genuine producing areas. Among all strains, Aspergillus niger ZJ-17 had the strongest growth promotion potential. Under the condition of no fertilization outdoors, ZJ-17 inoculation significantly promoted the growth, yield, and accumulation of effective components of A. dahurica var. formosana planted in the soil of genuine and non-genuine producing areas, with yield increases of 73.59% and 37.84%, respectively. To a certain extent, it alleviated the restriction without additional fertilization on the growth of A. dahurica var. formosana. Therefore, A. niger ZJ-17 has great application prospects in increasing yield and quality of A. dahurica var. formosana and reducing fertilizer application and can be actually applied in promoting the growth of A. dahurica var. formosana and producing biofertilizer.

Preparation and quality evaluation of total flavonoids microemulsion of "Pueraria lobata-Hovenia dulcis"

The effective components of flavonoids in the "Pueraria lobata-Hovenia dulcis" drug pair have low bioavailability in vivo due to their unstable characteristics. This study used microemulsions with amphoteric carrier properties to solve this problem. The study drew pseudo-ternary phase diagrams through titration compatibility experiments of the oil phase with emulsifiers and co-emulsifiers and screened the prescription composition of blank microemulsions. The study used average particle size and PDI as evaluation indicators, and the central composite design-response surface method(CCD-RSM) was used to optimize the prescription; high-dosage drug-loaded microemulsions were obtained, and their physicochemical properties, appearance, and stability were evaluated. The results showed that when ethyl butyrate was used as the oil phase, polysorbate 80(tween 80) as the surfactant, and anhydrous ethanol as the cosurfactant, the maximum microemulsion area was obtained. When the difference in results was small, K_(m )of 1∶4 was chosen to ensure the safety of the prescription. The prescription composition optimized by the CCD-RSM was ethyl butyrate(16.28%), tween 80(9.59%), and anhydrous ethanol(38.34%). When the dosage reached 3% of the system mass, the total flavonoid microemulsion prepared had a clear and transparent appearance, with average particle size, PDI, and potential of(74.25±1.58)nm, 0.277±0.043, and(-0.08±0.07) mV, respectively. The microemulsion was spherical and evenly distributed under transmission electron microscopy. The centrifugal stability and temperature stability were good, and there was no layering or demulsification phenomenon, which significantly improved the in vitro dissolution of total flavonoids.