Large Mobility Research Articles

Raman activity and high electron mobility of piezoelectric semiconductor GaSiX2 (X = N, P, and As) toward flexible nanoelectronic devices

Abstract Inspired by the urgent demand for novel multifunctional materials in advanced technology applications, herein, first-principles calculations are utilized to construct new two-dimensional GaSiX 2 (X = N, P, As) monolayers. After optimizing the GaSiX 2 crystal structures, their stabilities, Raman responses, piezoelectricity, and electronic/transport characteristics are systematically studied. Results from phonon dispersions, ab initio molecular dynamics simulations, elastic constants, and cohesive energies confirm the good dynamic, thermal, energetic, and mechanical stabilities of the proposed GaSiX 2 monolayers. Based on the Heyd–Scuseria–Ernzerhof approach, the GaSiX 2 exhibit semiconductor behaviors with favorable bandgaps for absorption of the visible spectrum of 1.82 for GaSiP2 and 1.43 eV for GaSiAs2 monolayer. In addition, the GaSiX 2 monolayers also show piezoelectric effects, and high in-plane piezoelectric coefficients d 11 are found for the GaSiP2 (−1.16 pm V − 1 ) and GaSiAs2 (−1.26 pm V − 1 ). The carrier mobilities of the GaSiX 2 are estimated by the deformation potential method for their transport properties. Along two in-plane transport directions, the carrier mobilities of the GaSiX 2 are anisotropy for holes and electrons. GaSiP2 and GaSiAs2 show large electron mobilities along the x axis of 2816.99 and 1211.41 cm2V−1s−1, respectively. Thus, the GaSiP2 and GaSiAs2 monolayers not only have high anisotropic electron mobilities but also favorable bandgaps and large piezoelectric coefficients, indicating potential applications of GaSiP2 and GaSiAs2 in electronic, photovoltaic, and piezoelectric devices. The findings of this study may provide insights into the GaSiX 2 monolayers for multifunctional applications.

Reversal of chirality in solutions and aggregates of chiral tetrachlorinated diperylene diimides towards efficient circularly polarized light detection.

Helicenes exhibit promise as active layer materials for circularly polarized light (CPL) detectors due to their strong chiroptical activity. However, their practical application is limited by the complicated synthesis and loosely solid-state packing. This study introduces a chiral induction strategy towards the synthesis of helicene derivatives, chiral tetrachlorinated diperylene diimides ((SSSS)-4CldiPDI or (RRRR)-4CldiPDI). When incorporating the chiral (S/R)-1-cyclohexylethyl (Cy) substituents, the chirality is directly transferred to the π-aromatic core and forms the PP- or MM-helicene subunit. Notably, (SSSS)-Cy induces preferred PP helicity while (RRRR)-Cy leads to the MM helicity in the monomers. However, these molecules exhibit reversed chirality in crystals, where (SSSS)-Cy controls MM helicity and (RRRR)-Cy induces PP helicity. Theoretical calculations reveal that the (SSSS)-PP structure demonstrates lower energy distribution in monomers, whereas the (SSSS)-MM structure exhibits lower energy in crystals. Then, the CPL detection based on n-type PDI-helicene derivatives is achieved by using (SSSS)-4CldiPDI or (RRRR)-4CldiPDI crystals. The maximum photocurrent dissymmetry factor gph of +0.16 for (RRRR)-4CldiPDI and -0.15 for (SSSS)-4CldiPDI is obtained. Our work demonstrates a novel chiral induction strategy for designing helicene-based materials with both high dissymmetry factor and large charge carrier mobility, which offers great potential for the advancement of CPL detection.

Atomic layer deposition of Sn-doped germanium diselenide for an As-free Ovonic threshold switch with low off-current.

This work introduces the atomic layer deposition (ALD) of Sn-doped GeSe2 (SnGS2) films for developing arsenic-free Ovonic threshold switch (OTS) devices with low off-current (Ioff) and desirable threshold voltage (Vt). The undoped GeSe2 film exhibits high Vt and low endurance characteristics despite its low Ioff originating from a large mobility gap. Such problems could be overcome by appropriate doping, and thus, Sn was doped into the GeSe2 film using a supercycle consisting of SnNx and GeSe2 subcycles. The co-injection of NH3 with Se-precursor ([(CH3)3Si]2Se) during the GeSe2 subcycle generated a reactive H2Se intermediate, which enhanced the reactivity and transformed the pre-deposited SnNx to SnSe2. The overall cation-to-anion ratio of the deposited films remained at approximately 1 : 2, with amorphous structure and smooth surface morphology. The planar OTS device using SnGS2 films with a Sn concentration of 9.6%, for which the crystallization temperature was >400 °C, showed the lowest Vt of ∼3.5 V and Ioff of ∼12.5 nA at half Vt and demonstrated switching endurance over 106 cycles. Furthermore, a vertical-type OTS device was fabricated using the same SnGS2 film using the excellent step coverage of ALD, exhibiting similar switching characteristics to its planar counterpart.

High-Performing Direct X-Ray Detection Made of One-Dimensional Perovskite-Like (TMHD)SbBr5 Single Crystal With Anisotropic Response.

3D and 2D organic hybrid perovskites, as well as double perovskites, have demonstrated their suitability for direct X-ray detection. However, the sensitivity and stability of 3D perovskite X-ray detectors are currently being hindered by the existing constraints on ion movement. Therefore, there is an immediate need to develop X-ray detectors that are both highly sensitive and stable while also being environmentally friendly. The novel low-dimensional perovskites demonstrate exceptional inherent stability and effectively mitigate ion migration, thereby showcasing their remarkable photoelectric performance. Inspired by this, a solution crystallization method is employed to synthesize novel single crystals (SCs) of one dimensional (1D) (TMHD)SbBr5. The dimensions of the chained (TMHD)SbBr5 SC are 13×1.3×1.2 mm3 in size. The device based on a perovskite chain (TMHD)SbBr5 exhibits unique anisotropic X-ray detection performance with a sensitivity of 62.8 and 30.5 µC Gyair -1cm-2 in the parallel and perpendicular orientations, respectively. It can lead to the directional movement of ions, resulting in large carrier mobility under the action of electric fields, and effectively increase the sensitivity to X-ray detection.

The classification evaluation of tight sandstone reservoir and the controlling factors of dessert reservoir in the fourth member of Xujiahe Formation in Tianfu area, central Sichuan Basin, China

The tight sandstone gas in the Xujiahe Formation of the Sichuan Basin offers substantial resources and strong exploration potential. However, identifying desirable reservoirs proves difficult due to factors such as low porosity and permeability, high heterogeneity, and the complex layering of sand bodies. To pinpoint the main factors influencing optimal zones in the tight sandstone reservoir of the fourth member, we systematically analyzed its petrology, physical properties, pore structure, and diagenesis. Our analysis shows that the primary rock type in the target layer is feldspar lithic sandstone, which has generally poor physical properties. The average porosity measures 6.62%, and the average permeability is 0.1495 × 10−3 m, categorizing it as an ultralow porosity and ultralow permeability reservoir. The lower limit of porosity is 6% and the lower limit of permeability is 0.1 × 10−3 m2. We classify the reservoir into two types based on a porosity threshold of 8% and a permeability threshold of 0.3 × 10−3 m. Type I reservoirs show relatively good physical properties, with their reservoir space mainly comprising large pores and high fluid mobility. Reservoir quality depends on both sedimentation and diagenesis, and the physical properties of delta front sand bodies exceed those of delta plain sand bodies. Compaction primarily affects reservoir density, followed by calcite and illite cementation. Additionally, the chlorite rim effectively preserves pores. Secondary dissolution pores formed by feldspar dissolution significantly enhance reservoir space, improving overall reservoir quality.

Fuzzy-based Bi-objective Energy Efficient Routing Protocol for Large Scale Mobile Ad-hoc Network

MANET is an infrastructure-less network, which is comprised of a greater number of nodes that are moving in a random manner. Establishing efficient and reliable routes is the crucial design issue in MANET. In addition, providing energy-efficient routes for performing communication operations in MANET is also a challenging goal. Increasing network lifetime and decreasing overall traffic load are the significant considerations while designing the MANET. An energy optimization routing mechanism with a fuzzy basis that is state-based and influenced by COVID-19 is used to prevent and control epidemics. Based on their lifespan and varying mobility speeds, it is dependent on energy optimization yield under various scenarios. Fuzzy-based bi-objective criteria in energy-efficient routing protocol for the mobile ad-hoc network to select the different constraints like link stability, bandwidth, and battery life. The main goal of this paper is to obtain the optimal solution to choose the best route, limit battery life, and change the movement of mobile nodes for large-scale mobile ad-hoc networks. It is demonstrated that the possible solution relates to the domain of selecting the variables by outlining the connection between the energy function’s variables. Researchers optimize a path's link lifespan, resulting in the choice of the shortest path being particularly efficient in COVID pandemic prevention and treatment.

Analytical and numerical study on radius of investigation in composite reservoirs

Radius of investigation (ROI) is of great significance in well testing and reserve estimation. The studies on ROI over the past decades were mainly focusing on homogeneous reservoirs. In heterogeneous formations, such as composite reservoirs and fractured reservoirs, the problem remains unsolved. Few ROI evaluation methods for composite reservoirs have been validated and commonly accepted. This paper conducts extensive analytical and numerical analysis on the pressure propagation of composite reservoirs, analyzing the limitations and misunderstandings of previous methods on the evaluation of ROI. The pressure solution of a two-zone composite reservoir is presented in the Laplace domain and is used to analyze the impact of heterogeneity parameters on pressure transient propagation and the evaluation of radius of investigation. A new ROI formula for composite reservoirs is proposed, which is in great agreement with the analytical solution. The study reveals that the inner zone of a composite reservoir cannot be treated as homogeneous when the pressure front approaches the interface of the two zones with high heterogeneity. A large mobility ratio will slow pressure propagation in composite reservoirs, while a low storativity ratio will increase the value of ROI. Reservoir simulation and real case studies are used to demonstrate the findings of the analytical study. The new study sheds insights into the pressure propagation and eases the calculation of ROI in composite reservoirs.

Physicochemical properties of La0.5Ba0.5Co1-xFexO3-δ (0 ≤ x ≤ 1) as positrode for proton ceramic electrochemical cells

We report on essential properties of materials in the series La0.5Ba0.5Co1-xFexO3-δ as positrodes for proton ceramic electrochemical cells (PCECs). The unit cell and thermochemical expansion coefficient (TCEC) of these cubic perovskites decrease with iron content x, the TCEC of La0.5Ba0.5FeO3-δ going as low as 11·10-6 1/K. The materials behave as LaMO3 perovskites with small band gaps and Ba acting as acceptors compensated by electron holes and oxygen vacancies. The electrical properties are dominated by p-type conduction with high large polaron mobilities for the Co-rich compositions at low temperatures, shifting towards small polaron mobilities with increasing Fe content. X-ray absorption spectroscopy (XAS) shows that Co is in a high spin state and takes on the main part of the cation oxidation state changes, and that hole states are in orbitals overlapping with the O 2p states, confirming the large polaronic behaviour, while holes on Fe are more localised at the cation. Hydration is more pronounced in inert atmospheres, as hydration of oxygen vacancies is easier than hydrogenation and increases with Fe content, in line with the commonly accepted finding that delocalization of holes disfavours protonation. Fe-rich compositions benefit from lower TCEC and higher hydration and hence expected proton permeability, at the cost of lower electronic conductivity. The surfaces are hydrophobic irrespective of Fe content, suggesting weak chemisorption of the underlaying water layer, possibly giving relatively many available surface sites for oxygen adsorption, but limited surface proton conductance – both of importance to positrodes for operando PCECs.

Advances in Fuel Cell Performance Using Simulation Analysis in Toshiba Energy Systems & Solutions Corporation

Toshiba’s Stationary Fuel Cell SystemToshiba Energy Systems & Solutions Corporation is developing hydrogen solution, which is a key technology to achieve carbon neutral. Now we are manufacturing the pure hydrogen fuel cell systems for stationary application. This fuel cell systems have some models up to 100kW, and in order to provide the larger electricity than 100kW, the 100kW system can be operated connecting several units up to 1MW.Toshiba's fuel cell systems have been achieved stable, long-term operation, high durability, and high energy efficiency. These features are realized by internal water management cell stack conflagration using porous carbon bi-polar plates. The porous bi-polar plates can humidify reactant gases supplied as vapor from the surface of the porous bi-polar plates and removes produced water through the porous bi-polar plates by the pressure difference between the reactant gases and the coolant water. This technology realizes ideal conditions in terms of water activity entire active area, suppressing overpotentials due to flooding and temperature and water activity distribution. This technology enables stable continuous operation up to 1 week and design life of 80,000 hours confirmed by demonstration tests, which is one of the highest in the world.Recent trends in fuel cell development include the growing expectation and demand for higher capacity and long durability fuel cell systems for stationary applications such as carbon neutral complexes and data centers, etc. In addition, demand for high power density fuel cell systems for large commercial mobility vehicles, such as buses and trucks, is also increasing. In order to meet this demand, Toshiba is developing elemental technologies for higher performance fuel cells.Development of advanced high performance fuel cellsIn order to improve cell performance, it is necessary to reduce ohmic, activation, and diffusion polarizations. Among these three overpotentials, a reduction of diffusion polarization is particularly important to achieve operation up to the high current density. To reduce diffusion polarization, the flow field of bi-polar plates must be designed to improve the limiting current density by efficient gas supply to the catalyst layer and to reduce mass transport resistance in the gas diffusion layer and catalyst layer.Toshiba has focused on reducing this diffusion polarization and is working on the flow field design using numerical simulation. As an example, Toshiba has developed the advanced numerical simulation by introducing mass transfer models of water evaporation and water absorption on the surface of a porous bi-polar plates into a commercially available electrochemical reaction and thermal fluidics 3D simulator.This porous bi-polar plates model was then used to perform parametric study of the flow field design, and determine parameters in terms of gas diffusivity, electrical resistance, and temperature and humidity distribution. And then, the advanced cell that incorporating designed bi-polar plates, thinner components, and a new catalyst was fabricated and evaluated. Figure 1 shows comparison of cell performance between conventional and advanced cells. The limiting current density of advanced cell is 3.6 times larger than that of conventional cell due to simulation-based flow field design and optimization of operating pressure. The application of these development items and optimization of operating conditions reduced each polarization and achieved a current density twice that of conventional cell. In the future, we aim to achieve even higher performance by improving catalytic activity and reducing cell resistance through thinner components. Figure 1

Emergency Management in Japan: Human Decision‐Making Strategy Analysis During Large‐Scale Earthquake

ABSTRACTIn the context of unexpected disasters, comprehending individual decision‐making strategy is essential for governmental policy formulation and evacuation planning. The main challenges stem from the absence of large‐scale mobility data and the complex influences of multiple factors on personal strategies. To address this, this study focuses on the 2011 Tohoku earthquake in Japan as a case, which struck at 14:46 on March 11, a typical working day. Decision‐making strategies regarding how people return home from their workplaces have emerged as a primary concern. Therefore, we construct a large human mobility database for the Greater Tokyo area, and develop an empirical prediction for decision‐making strategies following earthquakes with the consideration of multiple factors. Except for users' location‐based information, we extract the grid‐based stay areas from historical stay records (normal days before disasters) and discover the functions of these areas combined with points of interest located within them. Experimental results indicate the effectiveness of our proposed framework in strategy prediction. Besides, we conduct an explainable feature importance analysis of key factors, which also provides insights for understanding human decisions during disasters.

Numerical simulation of electrically pumped active vertical‐cavity surface‐emitting lasers diodes based on metal halide perovskite

AbstractMetal halide perovskites (MHP)‐based electrically pumped vertical‐cavity surface‐emitting lasers (EPVCSEL) are promising candidates in optoelectronics due to low‐carbon footprint solution processing method. However, significant challenges impede MHP‐EPVCSEL manufacturing: (1) Distributed Bragg Reflectors (DBRs) composed of typical electron transport layers (ETLs) and hole transport layers (HTLs) are not conductive enough. (2) Due to large mobility difference of typical ETLs and HTLs, carriers‐unbalanced injection leads to severe performance degradation. Herein, we propose a potential strategy to address such challenges using MAPbCl3 and CsSnCl3 as carrier transport layers with mobility 3 orders larger than typical ETLs and HTLs. Via transfer matrix method calculations, we find that the reflectance of DBRs composed of MAPbCl3 (130.5 nm)/CsSnCl3 (108 nm) is larger than 91% with 10 pairs of DBRs. Furthermore, the proposed EPVCSEL device simulation shows that MHP‐EPVCSEL has the potential to achieve room temperature continuous wave lasing with a threshold current density of ∼69 A cm−2 and output optical power ∼10−4 W. This work can provide a deep insight into the practical realization of MHP‐EPVCSEL.

Ultrafast Charge and Exciton Diffusion in Monolayer Films of 9-Armchair Graphene Nanoribbons.

Determining the electronic transport properties of graphene nanoribbons is crucial for assessing their suitability for applications. So far, this has been highly challenging both through experimental and theoretical approaches. This is particularly the case for graphene nanoribbons that are prepared by chemical vapor deposition, which is a scalable and industry-compatible bottom-up growth method that results in closely packed arrays of ribbons with relatively short lengths of a few tens of nanometers. In this study, the experimental technique of spatiotemporal microscopy is applied to study monolayer films of 9-armchair graphene nanoribbons prepared using this growth method, and combined with linear-scaling quantum transport calculations of arrays of thousands of nanoribbons. Both approaches directly resolve electronic spreading in space and time through diffusion and give an initial diffusivity approaching 200 cm2 s-1 during the first picosecond after photoexcitation. This corresponds to a mobility up to 550 cm2 V-1 s-1. The quasi-free carriers then form excitons, which spread with a diffusivity of tens of cm2 s-1. The results indicate that this relatively large charge carrier mobility is the result of electronic transport not being hindered by defects nor inter-ribbon hopping. This confirms their suitability for applications that require efficient electronictransport.

Isolation and characterisation of monolayer phosphorene analogues

Atomically thin group IV monochalcogenides or phosphorene analogues are a promising family of materials. Theoretical calculations predict that monolayers (MLs) should be semiconducting, ferroelectric and ferroelastic at room temperature, exhibit large charge mobilities and large non-linear optical response. Yet, experimental studies of these systems are scarce because of the difficulty to produce such MLs. Here we focus on two members of this family: GeSe and SnS. We demonstrate a simple mechanical exfoliation method to produce ML samples on gold substrates. We observe the evolution of the Raman scattering as a function of layers and the anisotropic optical response from reflectance contrast measurements. To the best of our knowledge this is the first report of mechanical exfoliation down to the ML of these materials and the first realisation of ML GeSe.

Molybdenum isotope behavior during subduction zone metamorphism

The molybdenum (Mo) isotope composition (defined as δ98Mo measured per mil relative to NIST-3134) of many modern arc systems and the upper continental crust is heavier than the mantle and most subducting slab lithologies. This observation has led to a model whereby fluids leaving the slab transfer isotopically heavy Mo preferentially to the mantle wedge, leaving the residual slab isotopically lighter. We explore this model via an Mo isotope study of the metasedimentary and mélange lithologies of the Catalina Schist in California. These rocks record subduction zone metamorphism over a wide range of high-pressure/low-to-medium temperature conditions.Mo isotope compositions of the metasedimentary rocks decrease with increasing metamorphic grade, from a δ98Momean of −0.04 ± 0.13 ‰ (1σ, n = 3) for the lawsonite albite facies to −0.38 ± 0.07 ‰ (1σ, n = 5) for the epidote–amphibolite facies. The highest grade [amphibolite facies] samples show a slight uptick in δ98Mo values, with a mean of −0.19± 0.14 ‰ (1σ, n = 4). When coupled with major and trace element variations, the changes in δ98Mo appear to reflect metamorphic effects rather than sedimentary source rock heterogeneity. The positive relationship between δ98Mo and [Mo] and negative relationship with Ce/Mo argue for progressive loss of Mo with isotope fractionation during increasing P-T conditions; the reversal of this trend, seen in the increase in δ98Mo between the epidote amphibolite and amphibolite facies may reflect a subsequent partial re-fertilization by fluids carrying isotopically heavy Mo. δ98Mo values in the mélange across all grades are highly variable, ranging from −1.75 to −0.19‰, consistent with large scale mobilization of Mo with isotope fractionation. A metasomatized amphibolite block and reaction rind show similar light isotope compositions and signs of Mo depletion and transport. Together these three whole-rock data sets demonstrate pervasive open system behavior and mobility of Mo in the Catalina Schist. LA-ICP-MS Mo measurement of minerals in the differing metasedimentary metamorphic grades indicates that Fe oxides and/or hydroxides, titanite, rutile, and epidote are important reservoirs of Mo but when comparing mineral Mo content and modal abundance to whole-rock Mo concentrations, several samples were found to have “missing Mo”, something that has been observed in other Mo inventory studies. We attribute this to sample heterogeneity between the thin section and whole-rock powder scales.

Enhancement of the thermoelectric figure of merit in the Dirac semimetal Cd3As2 by band-structure and -filling control

ABSTRACT Topological materials attract a considerable research interest because of their characteristic band structure giving rise to various new phenomena in quantum physics. Besides this, they are tempting from a functional materials point of view: Topological materials bear potential for an enhanced thermoelectric efficiency because they possess the required ingredients, such as intermediate carrier concentrations, large mobilities, heavy elements etc. Against this background, this work reports an enhanced thermoelectric performance of the topological Dirac semimetal Cd3As2 upon alloying the trivial semiconductor Zn3As2. This allows to gain fine-tuned control over both the band filling and the band topology in Cd3-x Zn x As2. As a result, the thermoelectric figure of merit exceeds 0.5 around x = 0.6 and x = 1.2 at elevated temperatures. The former is due to an enhancement of the power factor, while the latter is a consequence of a strong suppression of the thermal conductivity. In addition, in terms of first-principle band structure calculations, the thermopower in this system is theoretically evaluated, which suggests that the topological aspects of the band structure change when traversing x = 1.2 .

The Universal Neighborhood Effect Averaging in Mobility-Dependent Environmental Exposures.

The neighborhood effect averaging problem (NEAP) is a fundamental statistical phenomenon in mobility-dependent environmental exposures. It suggests that individual environmental exposures tend toward the average exposure in the study area when considering human mobility. However, the universality of the NEAP across various environmental exposures and the mechanisms underlying its occurrence remain unclear. Here, using a large human mobility data set of more than 27 000 individuals in the Chicago Metropolitan Area, we provide robust evidence of the existence of the NEAP in a range of individual environmental exposures, including green spaces, air pollution, healthy food environments, transit accessibility, and crime rates. We also unveil the social and spatial disparities in the NEAP's influence on individual environmental exposure estimates. To further reveal the mechanisms behind the NEAP, we perform multiscenario analyses based on environmental variation and human mobility simulations. The results reveal that the NEAP is a statistical phenomenon of regression to the mean (RTM) under the constraints of spatial autocorrelation in environmental data. Increasing travel distances and out-of-home durations can intensify and promote the NEAP's impact, particularly for highly dynamic environmental factors like air pollution. These findings illuminate the complex interplay between human mobility and environmental factors, guiding more effective public health interventions.

A CLASSIFICATION OF PASTORALISM IN SPAIN: UNDERSTANDING THE PAST TO ADDRESS PRESENT CHALLENGES

After centuries as a flagship economic activity, pastoralism in Spain is today in danger of collapse due to the simultaneous processes of abandonment and industrialisation. With a consensus on the need to revert this decline, a characterisation of pastoralism is needed in the design of an efficient framework for action. Through a participatory process with experts, we carried out this characterisation of Spanish pastoralism, identifying the most representative systems and communities. We studied the causes and consequences of pastoral evolution over the last 250 years, explained by biophysical, technological, governance and social parameters. We achieved a harmonised classification of eleven pastoral systems, classified into four groups with mobility parameters (large migratory systems, short-distance transterminance, daily mobile grazing and semi-wilderness). Large mobility systems were subdivided into ten pastoral communities, characterised by strong sociocultural ties beneath farm management. The consideration of pastoral systems and communities in policy can orient effective rural development, while optimising the allocation of resources for environmental conservation and climate neutrality. This article was published open access under a CC BY-NC 4.0 licence: https://creativecommons.org/licenses/by-nc/4.0/ .

CO2-EOR and storage in a low-permeability oil reservoir: Optimization of CO2 balanced displacement from lab experiment to numerical simulation

CO2 flooding can enhance oil recovery associated with CO2 storage, but its performance is often damaged by the gas channeling due to reservoir heterogeneity and the large CO2 mobility. Most current research focuses on chemical agents to prevent CO2 channeling, while there is less attention to reservoir engineering methods. In this study, a concept of balanced displacement was introduced to delay the gas channeling and achieve balanced development in a multi-layer and low-permeability block Y21. A series of lab experiments and numerical simulations were conducted to explore the best CO2 flooding scheme by considering three aspects of optimization. Layer grouping and well pattern and spacing adjustment were applied to seek for balanced utilization of geological reserves; gas channeling plugging and mobility control measures were taken to increase the CO2 swept volume; and the pressure control and injection-production optimization were carried out to improve the oil displacement efficiency. The results show that CO2 can reach miscible with crude oil in block Y21 under the original formation pressure, but gas breakthrough quickly occurs along the hydraulic fractures to the top of the structure. To obtain a balanced displacement, the layers of block Y21 should be divided into two groups for separate development. The current well pattern and spacing are suitable for CO2 flooding, which need not be adjusted. WAG injection with acid-resistant gel particles and foaming agents can be used to inhibit gas channeling. These measures can significantly improve the CO2 displacement profile in block Y21. The oil recovery factor can be increased by 10.01%, and 5.41 × 104 tons of CO2 can be stored. This study can provide valuable guidance for CO2-EOR and storage in low-permeability oil reservoirs.

Cardiac calcified amorphous tumor in a patient with lung cancer

BackgroundCalcified amorphous tumor of the heart is a rare non-neoplastic cardiac mass composed of calcified nodules over amorphous fibrous tissue with degeneration and some chronic inflammation. Calcified amorphous tumor is often associated with mitral annular calcification in patients with end-stage renal disease on dialysis. However, the exact etiology of calcified amorphous tumors remains uncertain.Case presentationA 77-year-old female with lung cancer showed a tumor with large mobility in the left ventricular outflow tract on transthoracic echocardiography. She had mitral annular calcification, although her renal function was normal. The tumor was excised surgically. Pathologically, the extracted specimen consisted of a calcified lesion without tumor tissue and was diagnosed as a calcified amorphous tumor.ConclusionsAs the patient had no other risk factors for calcified amorphous tumor except mitral annular calcification, we considered the association of blood coagulation abnormalities due to cancer-related thrombosis. This case suggests that calcified amorphous tumors may be associated with malignant tumors.

Ultrafast Charge Transfer Cascade in a Mixed-Dimensionality Nanoscale Trilayer

Innovation in optoelectronic semiconductor devices is driven by a fundamental understanding of how to move charges and/or excitons (electron-hole pairs) in specified directions for doing useful work, e.g. for making fuels or electricity. The diverse and tunable electronic and optical properties of two-dimensional (2D) transition metal dichalcogenides (TMDCs) and one-dimensional (1D) semiconducting single-walled carbon nanotubes (s-SWCNTs) make them good quantum confined model systems for fundamental studies on charge and exciton transfer across heterointerfaces. In nature, the photosynthetic apparatus achieves long-lived charge separation through a charge transfer cascade that consists of a series of thermodynamically downhill charge transfer reactions. Inspired by photosynthesis we create a unique mixed-dimensionality 2D/1D/2D MoS2/SWCNT/WSe2 hetero-trilayer. Photoexcitation of this trilayer heterostructure allows us to overcome both intralayer and interlayer exciton binding energies, resulting in coulombically unbound charges with microsecond recombination lifetimes. In contrast to previously demonstrated 2D/2D/2D trilayers based solely on monolayer TMDC layers, the very large charge mobilities and extended electron network of the 1D semiconducting SWCNT layer helps charges delocalize and diffuse away from the interface at which each type of charge is generated. Interestingly, the hetero-trilayer also appears to enable efficient hole transfer from SWCNTs to WSe2, which is not observed in the identically prepared WSe2/SWCNT heterobilayer, suggesting that new dynamic pathways may be opened by increasing the complexity of nanoscale heterostructures. Our work suggests "mixed-dimensionality" TMDC/SWCNT based hetero-trilayers as both interesting model systems for mechanistic studies of carrier dynamics at nanoscale heterointerfaces, and for potential applications in advanced optoelectronic systems.