Internal Distribution Research Articles

The application and development of electron microscopy for three-dimensional reconstruction in life science: a review.

Imaging technologies have played a pivotal role in advancing biological research by enabling visualization of biological structures and processes. While traditional electron microscopy (EM) produces two-dimensional images, emerging techniques now allow high-resolution three-dimensional (3D) characterization of specimens in situ, meeting growing needs in molecular and cellular biology. Combining transmission electron microscopy (TEM) with serial sectioning inaugurated 3D imaging, attracting biologists seeking to explore cell ultrastructure and driving advancement of 3D EM reconstruction. By comprehensively and precisely rendering internal structure and distribution, 3D TEM reconstruction provides unparalleled ultrastructural insights into cells and molecules, holding tremendous value for elucidating structure-function relationships and broadly propelling structural biology. Here, we first introduce the principle of 3D reconstruction of cells and tissues by classical approaches in TEM and then discuss modern technologies utilizing TEM and on new SEM-based as well as cryo-electron microscope (cryo-EM) techniques. 3D reconstruction techniques from serial sections, electron tomography (ET), and the recent single-particle analysis (SPA) are examined; the focused ion beam scanning electron microscopy (FIB-SEM), the serial block-face scanning electron microscopy (SBF-SEM), and automatic tape-collecting lathe ultramicrotome (ATUM-SEM) for 3D reconstruction of large volumes are discussed. Finally, we review the challenges and development prospects of these technologies in life science. It aims to provide an informative reference for biological researchers.

Two-dimensional inverse problem of fire location in the closed goaf of coal mine based on optical fiber sensors.

Monitoring the temperature to determine the fire source locations is essential for controlling the spontaneous combustion in the goaf. Optical fiber sensors are employed to measure the temperature distribution in the goaf. However, due to changes in the geological conditions and the influence of the falling rocks in the goaf, only sensors on the upper side of the uncompacted goaf, due to inclination and coal pillar, may remain. Unilateral sensors are located on the upper side of the goaf, while fire occurs in the center. To investigate the issue with linear unilateral sensors, a two-dimensional inverse method has been developed to determine the location of fire sources by considering heat transfer after a fire inside the goaf. The equations were theoretically solved using Green's function method to obtain the internal temperature distribution of the physical model of the goaf. Sensitivity analysis identified the most crucial parameters in the process of spontaneous heating at different temperature. The fire source location can be determined using a loop method based on the model calculations. We considered a case to validate the model. Accurately identifying the fire source location in the goaf using the unilateral sensors has an essential theoretical and practical significance for fire prevention and fighting.

Panoramic chemical imaging of opium alkaloids in Papaver somniferum by TOF-SIMS

Accurate mapping of opium alkaloids in Papaver somniferum (P. somniferum) is significant for comprehensively elucidating their biosynthetic pathways and metabolic regulations. Here we describe a panoramic chemical imaging strategy based on time-of-flight secondary ion mass spectrometry (TOF-SIMS) that enables a thorough and precise visualization of the spatial differentiation of five opium alkaloids (morphine, codeine, thebaine, papaverine and noscapine) in P. somniferum. Notably, the opium alkaloids exhibited enrichment in the capsule, pistil, receptacle and peduncle. Moreover, a series of cross sections of a capsule were imaged to reveal a three-dimensional horizon of internal distribution of opium alkaloids. Opium alkaloids were observed enriched within the pseudoseptum and the “tube-like” structure of the inner pod wall, witnessing a downward trend toward the stigmatic disk. Finally, in high spatial resolution mode of TOF-SIMS, direct single-cell level chemical mapping of opium alkaloids in the phloem of the vascular bundles of P. somniferum receptacle was achieved for the first time. The introduced imaging strategy can provide multi-dimensional insights into the spatial distribution of opium alkaloids in P. somniferum, and the findings are expected to facilitate shedding light on the biological activities of these pharmacologically valued alkaloids.

Examining the impact of topcodes adjustment on studies of gender earnings inequality in the US: evidence from March CPS data

ABSTRACT Topcoded survey data has been widely used for studies of gender earnings inequality. How robust are these studies to the choice of topcode adjustment methods? We examine this issue using the public-use March Current Population Survey data from 1979 to 2018 in the United States. In general, using more informative data and more sophisticated parametric procedure implies greater gender earnings inequality. Regression and mean decomposition analyses of gender earnings gap are quite robust to the choice of topcode correction methods. Nevertheless, topcode correction methods do matter significantly for studies of the relationship between gender earnings gap and some covariates (education) but not others (occupational characteristics). For researchers lacking access to internal data, the recommended topcode correction approach is SW/PC method. This method combines the benefits of using public data with replacement values that replicate the less topcoded internal data distribution while integrating parametric correction for the remaining topcoding bias.

Design and 3D Electrical Simulations for a Controllable Equal-Gap Large-Area Silicon Drift Detector.

In this study, a controllable equal-gap large-area silicon drift detector (L-SDD) is designed. The surface leakage current is reduced by reducing the SiO2-Si interface through the new controllable equal-gap design. The design of the equal gap also solves the problem whereby the gap widens due to the larger detector size in the previous SDD design, which leads to a large invalid area of the detector. In this paper, a spiral hexagonal equal-gap L-SDD of 1 cm radius is selected for design calculation, and we implement 3D modeling and simulation of the device. The simulation results show that the internal potential gradient distribution of the L-SDD is uniform and forms a drift electric field, with the direction of electron drift pointing towards the collecting anode. The L-SDD has an excellent electron drift channel inside, and this article also analyzes the electrical performance of the drift channel to verify the correctness of the design method of the L-SDD.

Перевод творчества Солженицына в режиме «внутреннего распространения» в Китае (1960–1980 гг.)

In China, the interest to the work of A. I. Solzhenitsyn arose soon after the publication of his story One Day in the Life of Ivan Denisovich in the journal New World with the permission of N. S. Khrushchev in 1962, which immediately attracted the attention of Chinese literary circles. However, the initial interest in Solzhenitsyn was connected with the political situation in China at that time. The period from the 1960s to the 1980s can be considered the initial stage of the translation of the writer’s work. Almost all the works translated during these years were marked by “internal distribution”. The purpose of this paper is to identify the features of the history of translation and publication of A. I. Solzhenitsyn’s work in the “internal distribution” mode with Chinese characteristics. In the course of the research, for the first time, a connection is established between the system of production of printed materials in the 1960–1980s in China and the process of translating the works of the Russian writer, which determines the scientific novelty of this work. The author of the article pays special attention to the analysis of the historical background of the implementation of the “internal distribution” regime in China. The implementation of such a regime in the 1960–1980s was inseparable from the social, political and cultural context of the time. Knowledge of the context and historical background of this phenomenon will help not only to understand the historical conditions for the translation of Solzhenitsyn’s works during this period, but also to clarify the general picture of the acceptance of the writer in China. The study reveals that the label “internal distribution” for a long time influenced the perception of Solzhenitsyn’s work by the Chinese audience, giving rise to a critical, negative attitude towards the writer himself and his works. However, with the disappearance of ideological pressure in the 1990s, a rational study of the work of A.I. Solzhenitsyn begins in the Chinese scientific community and it is evaluated precisely from the point of view of the literary heritage.

A high-performance infrared photoacoustic sensor with improved low-frequency response microphone

Infrared photoacoustic gas sensors with the advantages of good selectivity, low interference, fast response speed, good stability, high accuracy, good explosion-proof performance, high signal-to-noise ratio, and long service life, have developed rapidly in recent years. In order to solve the problem of poor low-frequency response performance of the MEMS piezoelectric thin film microphone sensor prepared with AlN and Mo thin films in infrared photoacoustic gas sensors, this article analyzes its principle and tests an improved solution. The internal stress distribution was changed through hot tempering experiments, significantly improving its structure. The article qualitatively and quantitatively analyzes the inherent mechanism of this phenomenon. The experimental results confirm that the improved scheme improves its response performance under low-frequency signals, with good stability and repeatability.

Translation and validation of a simplified Chinese version of the psychosocial assessment tool

BackgroundThe Psychosocial Assessment Tool (PAT2.0) is widely used to assess psychosocial risk in families of children with cancer. Our study aims to apply PAT2.0 to Chinese patients and assess the reliability, content validity, and construct validity of the Chinese version.MethodsA total of 161 participants completed the study, each with only one child diagnosed with cancer. Psychometric evaluations, including internal consistency, score distribution, test-retest reliability, and construct validity, were conducted.ResultsCronbach’s alpha values ranged from 0.732 to 0.843, indicating good internal consistency. Additionally, intraclass correlation coefficient values ranged from 0.869 to 0.984, indicating excellent test-retest reliability. The Simplified Chinese version of PAT2.0 demonstrated high construct validity in factor analyses and correlations with the General Functioning Subscale of the Family Assessment Device.ConclusionThe translation process of the Chinese version of PAT2.0 was successful, proving its applicability for psychosocial evaluation and interventions in families of children with cancer in China.

Investigation on cavitation enhancement on flash boiling atomization using two-dimensional slit nozzles

Flash boiling and cavitation are two important topics in internal phase changing flow and spray atomization studies. They have been proven to be effective in improving spray breakup process, and hypotheses are proposed that these two phenomena could have coupled effects to achieve even better atomization. But few quantitative studies have made direct comparisons on whether the introduction of cavitation into flash boiling will result in finer droplets. This investigation aims to address this issue with optically transparent, two-dimensional slit nozzles with varied geometries. The round corner is introduced to suppress the generation of cavitation at the inlet, and thermal boundary conditions are adjusted to trigger flash boiling. Results from high-speed backlit imaging and phase doppler interferometry unveil that the introduction of cavitation can enhance the flash boiling process throughout the increment of superheat degree, yet the enhancement efficiency is different as thermal conditions change, and is strongly correlated with internal bubble spatial distributions. A model is proposed to explain the governing factor of cavitation enhancement on flash boiling atomization.

Effect of fiber layout on low-velocity impact response of intralaminar hybrid carbon/glass fiber braided composite pipes under internal pressure

This study investigated the low-velocity impact behaviors of intralaminar hybrid carbon/glass braided composite pipes under internal pressure. The effects of intralaminar fiber layout and internal pressure on the mechanical responses, damage extension, and material cost-effectiveness were analyzed. The internal damage distribution of composite pipes with different hybrid fiber alternating numbers but identical mix ratios was evaluated through Micro-CT three-dimensional damage reconstructions. The yarn splitting of brittle carbon fiber materials was mutually prevented by the induction of intra-yarn debonding and delamination damages by hybridization with ductile glass fiber materials, which were prone to produce out-of-plane displacement and shear stresses under impact loading. A smaller hybrid fiber alternating unit was conducive to exploiting the hybrid impact toughening effect by avoiding pure reinforced fiber materials aggregated under the impactor. Internal pressure had a supporting effect on the composite pipe and was effectively synergistic with the hybridization effect. The change in the dominant damage mode resulted in significant reductions in impact deformation and damage severity compared to the unpressurized case.

Modulation of electrodes on the sensitivity of the Pockels effect

In order to improve the sensitivity of the system in the Pockels effect, a design scheme for adding antennas at both ends of the crystal is proposed. Firstly, the influence of the applied electric field on the refractive index of the crystal is explored, and the relationship between the applied electric field and the output of the system is deduced. Secondly, two different antenna models are designed (one is to connect the antenna directly to both ends of the crystal, and the other is to connect the antenna after coating on the crystal), the distribution of the applied electric field in the internal field of the crystal under different models is studied, and the corresponding input and output transfer functions are analyzed. The analysis shows that the sensitivity of the system is improved in different antenna modes, and the crystal coating has little effect on the sensitivity. In addition, the antenna model without coating is simple to install, but the internal field strength of the crystal shows a tendency to be large in the middle and small at both ends, so it is easier to produce electric field breakdown effect in the strong field. The internal field strength distribution of the coated crystal is approximately uniform field, and the field strength maximum is smaller than that of the non-coated antenna model, so crystal breakdown is not easy to occur in the strong field. Finally, the effectiveness of the theoretical analysis is verified by experiments.

Seeing in crowds: Averaging first, then max.

Crowding, a fundamental limit in object recognition, is believed to result from excessive integration of nearby items in peripheral vision. To understand its pooling mechanisms, we measured subjects' internal response distributions in an orientation crowding task. Contrary to the prediction of an averaging model, we observed a pattern suggesting that the perceptual judgement is made based on choosing the largest response across the noise-perturbed items. A model featuring first-stage averaging and second-stage signed-max operation predicts the diverse errors made by human observers under various signal strength levels. These findings suggest that different rules operate to resolve the bottleneck at early and high-level stages of visual processing, implementing a combination of linear and nonlinear pooling strategies.

A Method for Determination of Moment Contribution Ratio under Foundation Rotation in Shear Wall-Frame Systems

In shear wall-frame systems, the foundation rotation that may occur under the shear walls changes the displacements and interstory drift ratios and changes the internal force distribution. This study investigates the effect of foundation rotations under shear walls on internal force distribution in shear-frame systems. The originality of the study lies in considering parabolic loads and dynamic analysis (first mode), in addition to static uniform or triangular distributed loads, when determining the shear wall moment contribution ratio under the influence of foundation rotation. The shear wall contribution ratio, a key parameter in many earthquake codes, is defined as the ratio of the sum of bending moments taken by the shear walls at the base to the overturning moment. It plays a crucial role in determining the building’s behavior. Depending on this ratio, the load-reduction coefficient is changed. This study investigates the effect of foundation rotation on the moment distribution at the base for three different static load cases and the first mode in the dynamic analysis. The multi-story building is modeled as an equivalent sandwich beam. The moment contribution ratio (MCR) was calculated with the help of analytical solutions of the differential equations written for three different load cases in static conditions, and graphs were created for practical use directly calculating the MCR. In the methodology of the study, the initial step involves the calculation of the equivalent sandwich beam stiffness parameters and the foundational rotational spring. Subsequent to these calculations, the MCR values can be directly obtained with the help of graphs. This approach facilitates the rapid and practical determination of the MCR and can be used in the preliminary sizing phase to eliminate possible errors in the data entry of software that performs detailed analysis. In addition, in the presented study, it has been shown that taking a single mode into account is sufficient when calculating MCR values in dynamic analysis.

Impact behavior of a novel magnetorheological energy absorber based on wedge-shaped squeeze flow model

Magnetorheological (MR) energy absorbers (MREAs) have been extensively investigated as a means of dissipating impact energy and decreasing injury as well as used in a wide range of applications. When applied as an accidental collision buffer, however, problems can arise owing to the inertia of the sudden impact. In this study, a novel MREA with a gradient resistance gap structure working in a wedge-shaped squeeze flow model of a high-viscosity linear polysiloxane-based MR fluid was developed. The MREA has a continuously changing working gap and internal magnetic flux density gradient distribution representing a wedge-shaped structure. A Power-Law model inclusive of fluid minor losses (PLM)- of the damping force of an MREA with a wedge-shaped resistance gap was built to study the impact behavior. A second model also considered the effects of inertia (PLMI). The wedge angle was defined to quantitatively and comprehensively characterize the effects of the wedge-shaped resistance gap because of its significant influence on the dynamic characteristics. Two MREAs with wedge-shaped and equidistant working gaps were fabricated and tested using a drop tower facility with a mass of 600 kg. The experimental results show that the maximum damping force of the MREA with a wedge-shaped resistance working gap reached to as high as 235.8 kN and the dynamic range is increased by 6.5% compared to that with an equidistant working gap. The relative errors of the peak force for impact velocities between 2.8 and 4.2 m s−1 with no applied current were 1.84%–3.67% (PLM) and 0.63%–1.91% (PLMI), and with 3 A applied current were 2.35%–4.99% (PLM), and 1.24%–2.72% (PLMI), demonstrating that the PLMI-based model is capable of accurately predicting the dynamic behavior of the MREA.

The Bronze Age occupation of the Black Sea coast of Georgia—New insights from settlement mounds of the Colchian plain

AbstractAlong the lower course of the Rioni and several minor rivers, more than 70 settlement mounds (local name: Dikhagudzuba) have been identified by field surveys and remote sensing techniques. They give evidence of a formerly densely populated landscape in the coastal lowlands on the Colchian plain (western Georgia) and have been dated to the Bronze Age. As yet, limited information is available on their internal architecture, the chronology of the different layers and their palaeoenvironmental context. Based on archaeological sources, remote sensing measurements of three mounds and sediment cores from one mound and its closer surroundings, our study presents a review of the relevant literature and reveals the internal structure, distribution and spatial extent of the mounds. Geochemical and sedimentological analyses of element contents (X‐ray fluorescence) and granulometry helped to identify different stratigraphical layers and differentiate between natural facies and anthropogenic deposits; using the Structure‐from‐Motion technique the mounds' dimensions were calculated. The studied settlement mounds had relatively small dimension (varying from 30 to 100 m in diameter) and were similar in their stratigraphy. Measurement of elements that can identify types of human activity, notably metals and phosphorus, suggest changing intensities of human occupation, pastoral agriculture and metalworking through the occupation sequence. According to the 14C chronology, the formation of the settlements occurred during the first half of the second millennium B.C., which confirms the archaeological interpretation of their Bronze Age origin. The narrow age difference between the lowermost and uppermost anthropogenic layers indicates an intentional construction of the mounds, rather than a successive accumulation of construction debris due to the disintegration of loam bricks by weathering. Therefore, they are indeed mounds and not tells. It is most likely that the characteristic circular moats that surround them were the source of their construction material. Fluvial and alluvial processes in a warm and humid climate dominated the environment of the mounds.

High Frequency Modeling of Electric Machines Using Finite Element Analysis Derived Data

The use of wide band gap semiconductor switching devices in electric machine drives leads to a significant increase in power density and efficiency compared to conventional silicon-based solutions. However, this technology also presents challenges for the insulation design of electric machines since partial discharges (PDs) may occur due to high peak voltage stress as a result of fast and high frequency switching. To evaluate the risk of PD, it is necessary to understand the voltage distribution within the windings and associated insulation of an electric machine during converter operation. To this end a suitable high frequency model of the machine windings capable of predicting the internal voltage distribution is required. This paper proposes a method of constructing such a model based on finite element analysis (FEA) derived data. The FEA data used to parameterise the model in this work incorporates frequency dependant properties and homogenisation techniques to produce data which captures the high frequency behaviour of the machine. The developed model is compared with measurements in both frequency and time domains, demonstrating the utility and accuracy of the model.

Integrated strategy for real-time wind power fluctuation mitigation and energy storage system control

To address the impact of wind-power fluctuations on the stability of power systems, we propose a comprehensive approach that integrates multiple strategies and methods to enhance the efficiency and reliability of a system. First, we employ a strategy that restricts long- and short-term power output deviations to smoothen wind power fluctuations in real time. Second, we adopt the sliding window instantaneous complete ensemble empirical mode decomposition with adaptive noise (SW-ICEEMDAN) strategy to achieve real-time decomposition of the energy storage power, facilitating internal power distribution within the hybrid energy storage system. Finally, we introduce a rule-based multi-fuzzy control strategy for the secondary adjustment of the initial power allocation commands for different energy storage components. Through simulation validation, we demonstrate that the proposed comprehensive control strategy can smoothen wind power fluctuations in real time and decompose energy storage power. Compared with traditional empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD), and complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) decomposition strategies, the configuration of the energy storage system under the SW-ICEEMDAN control strategy is more optimal. Additionally, the state-of-charge of energy storage components fluctuates within a reasonable range, enhancing the stability of the power system and ensuring the secure operation of the energy storage system.

The influence of ring clearance on the performance of a double-suction centrifugal pump

Due to the complex structure of a double-suction pump's suction chamber, the flow in the pump's cavity is often ignored in numerical simulations because of difficulties in structured hexahedral meshing. However, the wear ring clearance interlinking the pump chamber leads the fluid at the impeller inlet directly to the impeller area. This significantly impacts the pump's internal flow field, so the influence of the clearance on the internal flow of a double-suction pump cannot be ignored. This paper develops four three-dimensional double-suction pump models with different wear ring clearances to investigate their influence on pump performance, and structured hexahedral meshes were used for all the computational domains. The clearances varied from 0.2 to 0.5 mm in 0.1 mm increments. The influences of the clearance on the energy loss, external characteristics, and internal flow field distribution of the pump were simulated via a verified computational fluid dynamics method. The results show that the wear ring leakage decreases with the flow rate and increases with wear ring clearance. The increase in backflow leads to an internal flow disorder inside the impeller, resulting in a decreased head and efficiency. Energy loss is mainly caused by increasing the turbulence entropy production with an increasing wear ring clearance. Also, the low-pressure region in the pump cavity expands to the volute with increasing clearance, and the impeller outlet pressure decreases. This study's research on wear ring clearance provides a reference for the design and application of double-suction centrifugal pumps.

Research on the Internal Flow Difference between Peak and Valley Conditions of Water Jet Propulsion Pump during Working at Hump Region

When we tested the water jet propulsion pump, we found that there were significant vibrations in the pump, especially at small flow points that deviated from the design conditions. The water jet propulsion pump is a mixed-flow pump with guide vane, which is commonly employed for water jet propulsion. However, the guide vane mixed-flow pump is susceptible to a phenomenon known as “hump”, which can cause flow disturbances, increased vibration, and noise when the pump operates within the hump region. According to the vibration phenomenon found in our experiment, the mechanism of vibration needs to be revealed. This study focuses on vorticity and turbulence distributions of a mixed flow water jet propulsion pump under the valley and peak operating conditions of the hump region. The research is conducted using experimental and numerical simulation methods. The SST k-ω turbulence model is employed for turbulence calculations. The experiments are conducted on a closed test rig for axial (mixed) flow pumps. A comparison of experimental and numerical simulation results of hydraulic performance curves are conducted to validate the accuracy of the numerical simulation. Cavitation flow structures of the critical cavitation stage under valley conditions and under peak conditions are compared. A comparative analysis is conducted to examine the differences in internal vortex core distribution and turbulence kinetic energy distribution between the valley and peak operating conditions when working within the hump region. The pressure and velocity vectors of the pump impeller blades and the velocity streamline distribution between the impeller and the guide vane blades are compared. To further analyze the flow state in different flow channels under valley and peak conditions, the streamline distribution at Span = 0.5 in the impeller and diffuser basin is extracted. This study provides theoretical foundations and technical support for the design of high-performance, low-vibration water jet propulsion pumps.

Enhancement and Broadening of the Internal Electric Field of Hole-Transport-Layer-Free Perovskite Solar Cells by Quantum Dot Interface Modification.

Hole-transport-layer-free perovskite solar cells have attracted strong interest due to their simple structure and low cost, but charge recombination is serious. Built-in electric field engineering is an intrinsic driver to facilitate charge separation transport and improve the efficiency of photovoltaic devices. However, the enhancement of the built-in electric field strength is often accompanied by the narrowing of the space charge region, which becomes a key constraint to the performance improvement of the device. Here, we propose an effective regulation method, the component engineering of quantum dots, to enhance the strength of the built-in electric field and broaden the range of space charge. By using all inorganic CsPbBrxI3-x (x = 0, 1, 2, 3) quantum dot interface modification to passivate the defects of MAPbI3 perovskite films, the regulation law of quantum dot components on the work function of perovskite films was revealed, and the mechanism of their influence on the internal electric field intensity and space charge region distribution was further clarified, thereby fundamentally solving the serious problem of charge recombination. As directly observed by electron-beam-induced current (EBIC), the introduction of CsPbBr2I quantum dots can effectively enhance the interfacial electric field intensity, widening the space charge region from 160 to 430 nm. Moreover, the efficiency of the hole-free transport layer perovskite solar cells modified by CsPbBr2I quantum dots was also significantly enhanced by 1.5 times. This is an important guideline for electric field modulation and efficiency improvement within photovoltaic devices with other simplified structures.