Complex Three-dimensional Structures Research Articles

Three-dimensional simulation of electron extraction process and optimization of magnetic field based on multi-aperture structure of negative hydrogen ion source

In most of the simulations of the extraction region of negative hydrogen ion sources, the single-aperture simulation is often adopted by researchers to study the plasma phenomenon due to its small simulation domain and short calculation time. However, due to the complex three-dimensional magnetic field structure in the extraction region of the negative hydrogen ion source, the single aperture often does not meet the periodicity. In this paper, the complex three-dimensional magnetic field topology is established. The magnetic field includes the magnetic filter field and the magnetic deflection field. The influence of the plasma sheath is taken into account. The electron extraction process in the multi-aperture structure of the extraction region of a negative hydrogen ion source is numerically calculated using the PIC method. Besides, the magnetic field structure is optimized. Ultimately, the electron beam uniformity near the plasma grid is improved effectively, which has certain guiding significance for engineering application.

A novel temperature-resistant fracturing fluid for tight oil reservoirs: CO2-responsive clean fracturing fluid

With the increasing demand for oil and gas resources, deep tight oil and gas reservoirs have gradually become the focus of global oil and gas exploration and development. Hydraulic fracturing technology based on water-base fracturing fluid plays a more and more important role in improving the recovery of tight oil reservoirs. Under the background of global CO2 emission reduction, a CO2-responsive clean fracturing fluid with controllable gelling/gel breaking at high temperatures was constructed in this paper. The system was not only friendly to the reservoir and environment, but also overcame the shortcomings of the traditional clean fracturing fluid with undesirable temperature resistance. The viscosity characteristics and viscoelastic behavior of temperature-resistant clean fracturing fluid were investigated through high-temperature rheology experiments. The interaction between fluid and rock was investigated through the core flow experiment. The results showed that the clean fracturing fluid had the characteristics of good CO2 responsiveness, excellent shear resistance at high temperatures, high drag reduction, satisfactory gel breaking performance, low filtration and low core damage. The complex three-dimensional network structure formed by the intertwined micelles and vesicles improves the temperature resistance of the clean fracturing fluid. It is expected that the fluid can not only be used to improve oil recovery in tight oil reservoirs, but also be used to solve the leakage problem in CO2 storage underground.

Modeling human liver organ development and diseases with pluripotent stem cell-derived organoids.

The discoveries of human pluripotent stem cells (PSCs) including embryonic stem cells and induced pluripotent stem cells (iPSCs) has led to dramatic advances in our understanding of basic human developmental and cell biology and has also been applied to research aimed at drug discovery and development of disease treatments. Research using human PSCs has been largely dominated by studies using two-dimensional cultures. In the past decade, however, ex vivo tissue "organoids," which have a complex and functional three-dimensional structure similar to human organs, have been created from PSCs and are now being used in various fields. Organoids created from PSCs are composed of multiple cell types and are valuable models with which it is better to reproduce the complex structures of living organs and study organogenesis through niche reproduction and pathological modeling through cell-cell interactions. Organoids derived from iPSCs, which inherit the genetic background of the donor, are helpful for disease modeling, elucidation of pathophysiology, and drug screening. Moreover, it is anticipated that iPSC-derived organoids will contribute significantly to regenerative medicine by providing treatment alternatives to organ transplantation with which the risk of immune rejection is low. This review summarizes how PSC-derived organoids are used in developmental biology, disease modeling, drug discovery, and regenerative medicine. Highlighted is the liver, an organ that play crucial roles in metabolic regulation and is composed of diverse cell types.

Spatial-Temporal Dynamics at the Interface of 3D-Printed Photocurable Thermoset Resin Layers

Additive manufacturing (AM) is used to fabricate polymeric materials into complex three-dimensional (3D) structures. As the 3D structure is built by sequential layer-by-layer deposition of filaments dispensed from a translating nozzle (in the case of extrusion-based printing), defects often form at the filament-filament interface. The out-of-equilibrium structural development that occurs during the printing process is difficult to directly measure by quantitative means, limiting our understanding of the physical mechanisms at play. Here, we utilize in operando X-ray photon correlation spectroscopy (XPCS) measurements with microbeam capability to probe the real-time structural evolution at the filament-filament interface during extrusion 3D printing. We investigate the solidification of a dual-cure (UV/thermal) acrylate/epoxy resin during multilayer 3D printing as a rational model by tracking the nanoscale motion of filler particles embedded in the resin. The spatially and temporally resolved dynamics (on length scales from several nm to a few hundreds of nm and time scales of 10–3 < t < 103 seconds) are measured during the deposition of a single filament as well as during the deposition of a second layer on top of the cured underlayer. The addition of a second layer introduces structural perturbations at the interface and results in accelerated interfacial dynamics compared to those of the cured underlayer. However, as time proceeds, the local dynamical heterogeneity disappears, and the evolution of the dynamics progresses uniformly within the entire interfacial region. The homogeneity across the interface results from the formation of an interpenetrated epoxy network that spans across the first and second filaments. This homogeneous interface is responsible for the isotropic tensile properties of a 3D-printed sample that are independent of print direction and nearly the same as the bulk (non-3D-printed) sample. The XPCS microrheology approach provides insight into the dynamics-process-property relationship at the printed filament interfaces.

DOP08 Cellular and molecular interaction of MAIT in mucosal tissue and their role in inflammatory bowel disease

Abstract Background Inflammatory bowel disease (IBD) manifests as chronic inflammation of the gastrointestinal tract and is characterized by a deregulated immune response targeting the gut microflora. Mucosal-associated invariant T (MAIT) cells have been identified as a possible key player in IBD. Activated MAIT cells produce cytokines including IL-26, a newly discovered cytokine involved in the pathology of IBD. Interestingly, IL-26 is not expressed in mice and therefore its effect on the course of inflammation has not been yet fully investigated. Similarly, studies employing human cell cultures often provide limited results as they cannot fully mimic the complex three-dimensional structure of the intestinal tissue. A great hope is placed in the development of models of human diseases using organoids - 3D structures that better recapitulate the architecture and functionality of tissues. Methods Our laboratory recently described a model of intestinal inflammation based on human iPSCs-derived intestinal organoids (IOs). Taking advantage of this model, we investigate the influence of the cytokine IL-26 on the course of IBD. Moreover, we elucidate the influence of MAIT cells on the pathogenesis of IBD by studying their pathways of activation in vitro, and subsequently their interaction with inflamed tissues through the co-culture with IOs. Results After stimulation, IOs mimic the pro-inflammatory microenvironment and express various cytokines and chemokines. Moreover, IOs express MR1 which is recognised by the invariant TCR receptor of the MAIT cells. IOs express functional IL-26 receptor and respond to this cytokine. MAIT cells isolated from human blood show production cytokines including IL-26 and effector molecules upon in vitro activation. Their response differs depending on the origin of the stimuli. Conclusion IOs form complex structures and immunocompetent environment allowing to study of intestinal inflammation. IOs consist of various cell types, but not immune cells. Taken together with MR1 and cytokines expression we show that IOs can activate MAIT cells, and they serve as a relevant model for in vitro study of their biology. Moreover, IOs respond to IL-26, so they also provide a relevant model to elucidate the role of this cytokine. We expect that this study will contribute to our understanding of the processes underlying the progression of IBD, and lead to the design of new therapeutic targets for the treatment of idiopathic intestinal inflammation.

Investigation of the three-dimensional flow field for proton exchange membrane fuel cell with additive manufactured stainless steel bipolar plates: Numerical simulation and experiments

A bipolar plate with a complex three-dimensional (3D) flow field structure could bring better performance of proton exchange membrane fuel cell (PEMFC). In this paper, three types of 3D flow field bipolar plates with different porosity (M1, M2 and M3) and a conventional two-dimensional (2D) serpentine flow field bipolar plate (SP), were fabricated using selective laser melting (SLM). The forming quality of the bipolar plate was determined. The distribution characteristics of current density, oxygen, water content and temperature in different flow field structures and their effects on the performance of PEMFC were analyzed by numerical simulation. By using T3-100 cell test system and MTS exceeded E44 electronic universal test system, the polarization test and contact resistance test were conducted on the conventional SP bipolar plate and the M3 bipolar plate. Results show that the different bipolar plates prepared by the SLM process exhibit high forming quality, and the forming error for the 3D flow field bipolar plates is less than 4%. The M3 flow field exhibits the best capabilities for heat and mass transfer and water management. The M3 flow field produces a maximum power density of 0.547 W/cm2, which is 8.96% higher than that of the SP flow field. This is attributed to the more uniform distribution of gas and liquid in the M3 flow field as well as the lower contact resistance.

Thermal Modeling of Polyamide 12 Powder in the Selective Laser Sintering Process Using the Discrete Element Method.

Selective laser sintering (SLS) is one of the key additive manufacturing technologies that can build any complex three-dimensional structure without the use of any special tools. Thermal modeling of this process is required to anticipate the quality of the manufactured parts by assessing the microstructure, residual stresses, and structural deformations of the finished product. This paper proposes a framework for the thermal simulation of the SLS process based on the discrete element method (DEM) and numerically generated in Python. This framework simulates a polyamide 12 (PA12) particle domain to describe the temperature evolution in this domain using simple interaction laws between the DEM particles and considering the exchange of these particles with the boundary planes. The results obtained and the comparison with the literature show that the DEM frame accurately captures the temperature distribution in the domain scanned by the laser. The effect of laser power and projection time on the temperature of PA12 particles is investigated and validated with experimental settings to show the reliability of DEM in simulating powder-based additive manufacturing processes.

CRABP-I Expression Patterns in the Developing Chick Inner Ear.

The vertebrate inner ear is a complex three-dimensional sensorial structure with auditory and vestibular functions, regarded as an excellent system for analyzing events that occur during development, such as patterning, morphogenesis, and cell specification. Retinoic acid (RA) is involved in all these development processes. Cellular retinoic acid-binding proteins (CRABPs) bind RA with high affinity, buffering cellular free RA concentrations and consequently regulating the activation of precise specification programs mediated by particular regulatory genes. In the otic vesicle, strong CRABP-I expression was detected in the otic wall's dorsomedial aspect, where the endolymphatic apparatus develops, whereas this expression was lower in the ventrolateral aspect, where part of the auditory system forms. Thus, CRABP-I proteins may play a role in the specification of the dorsal-to-ventral and lateral-to-medial axe of the otic anlagen. Regarding the developing sensory patches, a process partly involving the subdivision of a ventromedial pro-sensory domain, the CRABP-I gene displayed different levels of expression in the presumptive territory of each sensory patch, which was maintained throughout development. CRABP-I was also relevant in the acoustic-vestibular ganglion and in the periotic mesenchyme. Therefore, CRABP-I could protect RA-sensitive cells in accordance with its dissimilar concentration in specific areas of the developing chick inner ear.

Application of artificial spawning substrates to support lacustrine fish recruitment and fisheries enhancement in a Chinese lake

Lake littoral zones with abundant submerged vegetation are considered to harbor diverse biotic communities and additionally serve as spawning grounds for important fishery resources. In recent decades, due to various human activities submerged vegetation in lakes have declined dramatically resulting in the function loss of spawning grounds. In order to enhance the recruitment of lacustrine fish (mainly Carassius auratus and Cyprinus carpio) and the proliferation of fishery resources, we explored a method of constructing artificial spawning ground based on artificial spawning substrate in lake. The results of present study indicate that the artificial substrates with complex and dense three-dimensional structure which have enough space to enable material exchange and oxygen circulation could be efficient to enhance fish recruitment. The water temperature of spawning peaks of artificial substrates were within the range of 20 ~ 25°C, and the water temperature provides a basis for the deployment period of artificial spawning grounds. The spawning substrate in the upper layer of water column was more attractive for fish to spawn. The above results provide guidance for the deployment of artificial spawning grounds from both temporal and spatial scales. Observations on the behavior of aggregations found that spawning activities mainly occurred at night and in the early morning. The abundance of larger individuals (&amp;gt;20 cm), as potential spawning groups, increased during this period. The above findings are informative to the construction and management of artificial spawning ground in lakes.

Emergence of layered nanoscale mesh networks through intrinsic molecular confinement self-assembly.

Block copolymer self-assembly is a powerful tool for two-dimensional nanofabrication; however, the extension of this self-assembly concept to complex three-dimensional network structures is limited. Here we report a simple method to experimentally generate three-dimensional layered mesh morphologies through intrinsic molecular confinement self-assembly. We designed triblock bottlebrush polymers with two Janus domains: one perpendicular and one parallel to the polymer backbone. The former enforces a lamellar superstructure that intrinsically confines the intralayer self-assembly of the latter, giving rise to a mesh-like monoclinic (54°) M15 network substructure with excellent long-range order, as well as a tetragonal (90°) T131 mesh. Numerical simulations show that the spatial constraints exerted on the polymer backbone drive the assembly of M15 and yield T131 in the strong segregation regime. This work demonstrates that intrinsic molecular confinement is a viable path to bottom-up assembly of new geometrical phases of soft matter, extending the capabilities of block copolymer nanofabrication.

Improvement of atmospheric jet-array plasma uniformity assisted by artificial neural networks

Atmospheric pressure plasma jet (APPJ) arrays have shown a potential in a wide range of applications ranging from material processing to biomedicine. In these applications, targets with complex three-dimensional structures often easily affect plasma uniformity. However, the uniformity is usually crucially important in application areas such as biomedicine, etc. In this work, the flow and electric field collaborative modulations are used to improve the uniformity of the plasma downstream. Taking a two-dimensional sloped metallic substrate with a 10° inclined angle as an example, the influences of both flow and electric field on the electron and typical active species distributions downstream are studied based on a multi-field coupling model. The electric and flow fields modulations are first separately applied to test the influence. Results show that the electric field modulation has an obvious improvement on the uniformity of plasma while the flow field modulation effect is limited. Based on such outputs, a collaborative modulation of both fields is then applied, and shows a much better effect on the uniformity. To make further advances, a basic strategy of uniformity improvement is thus acquired. To achieve the goal, an artificial neural network method with reasonable accuracy is then used to predict the correlation between plasma processing parameters and downstream uniformity properties for further improvement of the plasma uniformity. An optional scheme taking advantage of the flexibility of APPJ arrays is then developed for practical demands.

Engineering In vitro Models: Bioprinting of Organoids with Artificial Intelligence

In the last decade, organoids have gained popularity for developing mini-organs to support advancements in the study of organogenesis, disease modeling, and drug screening and, subsequently, in the development of new therapies. To date, such cultures have been used to replicate the composition and functionality of organs such as the kidney, liver, brain, and pancreas. However, depending on the experimenter, the culture environment and cell conditions may slightly vary, resulting in different organoids; this factor significantly affects their application in new drug development, especially during quantification. Standardization in this context can be achieved using bioprinting technology-an advanced technology that can print various cells and biomaterials at desired locations. This technology offers numerous advantages, including the manufacturing of complex three-dimensional biological structures. Therefore, in addition to the standardization of organoids, bioprinting technology in organoid engineering can facilitate automation in the fabrication process as well as a closer mimicry of native organs. Further, artificial intelligence (AI) has currently emerged as an effective tool to monitor and control the quality of final developed objects. Thus, organoids, bioprinting technology, and AI can be combined to obtain high-quality in vitro models for multiple applications.

Imitating the microenvironment of native biofilms using nanofibrous scaffolds to emulate chronic wound infections.

Three-dimensional scaffolds of electrospun fibers are widely investigated for in vitro human tissue engineering, but to date, their application in the cultivation of bacterial biofilms has been neglected. In contrast, in a clinical setting, biofilms have received increasing recognition as major determinants of severe and chronic tissue infections, illustrating their immense threat to global public health. Their complex three-dimensional structure enables their persistence in harsh infection environments, tight attachment to human tissue and reduced susceptibility to antimicrobials. For the investigation of biofilm formation and persistence and for the development of novel infection therapies, mimicking the complex biofilm architecture with adequate in vitro models is essential. In this study, electrospun nanofibers were designed to simulate the matrix of native biofilms to serve as scaffolds for a novel biofilm model, which provides an in vivo-like growth environment and comprises biofilm-tissue interfaces. The three-dimensional scaffolds closely imitate the composition and structure of the matrix, while providing high mechanical support. The specific material properties of the developed scaffolds promote bacterial adhesion, infiltration, and homogenous distribution throughout the fiber network. Furthermore, matrix production and increased tolerance against antibiotics were proven, verifying adequate biofilm formation and maturation. In combination with human ex vivo wound models, the chronic state of infected wounds could be emulated allowing for investigation of biofilm-tissue interfaces and biofilm-host interactions. The here-described biofilm model based on nanofibers represents a valuable tool for simulating biofilm-associated infections in a pathophysiologically relevant manner paving new grounds for a multitude of possible applications beyond infection research.

Recellularization of Acellular Xeno Kidney Scaffold: An In Vivo Method to Generate Bioartificial Kidney.

A significant hurdle for kidney tissue engineering is reproducing the complex three-dimensional structure of the kidney. In our study, a stepwise approach of generating a reproducible Xeno kidney scaffold from a goat kidney is described, which can be implanted and recellularized by host cells. We have proposed a combination of sodium dodecyl sulfate and Triton-X-100-based protocol to generate a reproducible Xeno kidney scaffold, which was then analyzed by histology, DNA quantification, SEM, and renal angiography. Further, a small portion from the cortico-medullar region of the acellular scaffold was implanted in the rat's kidney subcapsular pocket for a period of 1 month, to check the recruitment of host cells into the scaffold. Post implantation, the extracellular matrix of the scaffold was well preserved and it did not induce any damage or inflammation in the native kidney. Implantation of the Xeno scaffold resulted in apparent early vascularization which helped in the recruitment of the host cells, which was characterized by histology, immunohistochemistry, and scanning electron microscopy. Implanted Xeno scaffold showed AQP-1, Nephrin, α-SMA, and VEGF expression in proximal tubules and renal glomerulus. Importantly, Ki-67 and WTAP-expressing cells were also observed near proximal tubules suggesting a high level of proliferation in the scaffold. Thus, showing the potential of Xeno kidney development that can be recellularized by the host cell to engineer into a functional kidney.

Construction of Complex Three-Dimensional Structures of the Aorta of a Particular Patient Using Finite Analytical Formulas

Construction of Complex Three-Dimensional Structures of the Aorta of a Particular Patient Using Finite Analytical Formulas

Three-dimensional nanofabrication via ultrafast laser patterning and kinetically regulated material assembly.

A major challenge in nanotechnology is the fabrication of complex three-dimensional (3D) structures with desired materials. We present a strategy for fabricating arbitrary 3D nanostructures with a library of materials including metals, metal alloys, 2D materials, oxides, diamond, upconversion materials, semiconductors, polymers, biomaterials, molecular crystals, and inks. Specifically, hydrogels patterned by femtosecond light sheets are used as templates that allow for direct assembly of materials to form designed nanostructures. By fine-tuning the exposure strategy and features of the patterned gel, 2D and 3D structures of 20- to 200-nm resolution are realized. We fabricated nanodevices, including encrypted optical storage and microelectrodes, to demonstrate their designed functionality and precision. These results show that our method provides a systematic solution for nanofabrication across different classes of materials and opens up further possibilities for the design of sophisticated nanodevices.

Finite element mesh refinement for in-plane and out-of-plane vibration of variable geometrical Timoshenko beams based on superconvergent vibration modes

PurposeIn this paper, a superconvergent patch recovery method is proposed for superconvergent solutions of modes in the finite element post-processing stage of variable geometrical Timoshenko beams. The proposed superconvergent patch recovery method improves the solution speed and accuracy of the finite element analysis of a curved beam. The free vibration and natural frequency of the beam were considered for studying forced vibrations and structural resonance. Beam vibration mode analysis was performed for high-precision vibration mode solutions and frequency values. The proposed method can be used to compute beam vibration modes of beams with different shapes and boundary conditions as well as variable cross sections and curvatures. The purpose of this paper is to address these issues.Design/methodology/approachAn adaptive method was proposed to analyse the in-plane and out-of-plane free vibrations of the variable geometrical Timoshenko beams. In the post-processing stage of the displacement-based finite element method, the superconvergent patch recovery method and high-order shape function interpolation technique were used to obtain the superconvergent solution of mode (displacement). The superconvergent solution of mode was used to estimate the error of the finite element solution of mode in the energy form under the current mesh. Furthermore, an adaptive mesh refinement was proposed by mesh subdivision to derive an optimised mesh and accurate finite element solution to meet the preset error tolerance.FindingsThe results computed using the proposed algorithm were in good agreement with those computed using other high-precision algorithms, thus validating the accuracy of the proposed algorithm for beam analysis. The numerical analysis of parabolic curved beams, beams with variable cross sections and curvatures, elliptically curved beams and circularly curved beams helped verify that the solutions of frequencies were consistent with the results obtained using other specially developed methods. The proposed method is well suited for the mesh refinement analysis of a curved beam structure for analysing the changes in high-order vibration mode. The parts where the vibration mode changed significantly were locally densified; a relatively fine mesh division was adopted that validated the reliability of the mesh optimisation processing of the proposed algorithm.Originality/valueThe proposed algorithm can obtain high-precision vibration solutions of variable geometrical Timoshenko beams based on more optimized and reasonable meshes than the conventional finite element method. Furthermore, it can be used for vibration problems of parabolic curved beams, beams with variable cross sections and curvatures, elliptically curved beams and circularly curved beams. The proposed algorithm can be extended for application in superconvergent computation and adaptive analysis of finite element solutions of general structures and solid deformation fields and used for adaptive analysis of more complex plates, shells and three-dimensional structures. Additionally, this method can analyse the vibration and stability of curved members with crack damage to obtain high-precision vibration modes and instability modes under damage defects.

Fabrication of Glass Microchannels Using Plant Roots and Nematodes

Microchannels have been studied actively in recent years. Various types of materials are used for fabricating microchannels in different types of applications including polymers, and ceramics. Since glass materials have appealing properties such as hardness, transparency, thermal resistance, and chemical resistance, they are used in biomedical devices and microfluidic application. Glass microchannel fabrication methods include chemical etching, imprinting, and 3D printing. This paper proposes unprecedented methods to fabricate glass microchannels using plant roots growth and nematodes migration. The microchannels fabricated by these methods have a complex three-dimensional structure, and the smallest channels have a diameter of several tens of micrometers in the glass. Although glass is attractive material, it is challenging to sinter the green body to fully dense and transparent solid structure. Hence, experiments were also conducted to establish a fabrication technique for transparent silica glass.

Pulmonary nodule detection based on IR-UNet + + .

Lung cancer is one of the cancers with the highest incidence rate and death rate worldwide. An initial lesion of the lung appears as nodules in the lungs on CT images, and early and timely diagnosis can greatly improve the survival rate. Automatic detection of lung nodules can greatly improve work efficiency and accuracy rate. However, owing to the three-dimensional complex structure of lung CT data and the variation in shapes and appearances of lung nodules, high-precision detection of pulmonary nodules remains challenging. To address the problem, a new 3D framework IR-UNet + + is proposed for automatic pulmonary nodule detection in this paper. First, the Inception Net and ResNet are combined as the building blocks. Second, the squeeze-and-excitation structure is introduced into building blocks for better feature extraction. Finally, two short skip pathways are redesigned based on the U-shaped network. To verify the effectiveness of our algorithm, systematic experiments are conducted on the LUNA16 dataset. Experimental results show that the proposed network performs better than several existing lung nodule detection methods with the sensitivity of 1 FP/scan, 4 FPs/scan, and 8 FPs/scan being 90.13%, 94.77%, and 95.78%, respectively. Therefore, it comes to the conclusion that our proposed model has achieved superior performance for lung nodule detection.

RENDERING OF INHOMOGENEOUS VOLUMES USING PERTURBATION FUNCTIONS

Modeling of light transmission in heterogeneous volumes is of great importance in many fields, such as medical imaging, scientific visualization and synthesis of realistic images. Visual effects use complex three-dimensional structures such as smoke and clouds. However, modeling light transmission requires many calculations. For example, Monte-Carlo methods, which are based on path tracing, require the construction of a huge number of light paths. At the same time, each light path consists of thousands of scattering parts. A method for rendering inhomogeneous volumes using perturbation functions is presented. An approach is proposed for sampling light transmission paths in inhomogeneous media. The approach is based on the radiation transfer equation, using the integral formulation of the direct scattering algorithm. Bounding shells based on perturbation functions are used. To speed up calculations an inhomogeneous medium is divided into homogeneous and residual parts. The residual part is the difference between an inhomogeneous and homogeneous medium. For a homogeneous part light transmission paths are constructed in an analytical form. Next, the path-tracing algorithm is used. Samples in the light transmission path in the homogeneous and residual parts are made separately. This minimizes the costly calculations of direct scattering coefficients that change when traversing space. The method has advantages in comparison with approaches using an octal tree, with a large volume resolution the efficiency of calculations increases. The results of the work are integrated into the path tracer. Objects based on perturbation functions as an acceleration structure are used. The empty space is determined and approximate local extremes of the base volumes are stored. Objects based on perturbation functions adapt to volume uniformity. Voluminous data sets based on voxels are stored. Performance is compared using the number of queries, visualization time, root mean square error and metrics, that is, the search in units of variance.