Three-dimensional Stacking Research Articles

Chapter 9. Albertine Rift Stratigraphy 1: Sedimentary Architecture

A persistent problem that has hampered a general understanding of Albertine Rift early continental rift basins has been the lack of a high-resolution stratigraphic framework within which to correlate sediments across their onshore outcrop. Crucial to resolving this problem is resolving how the three-dimensional stacking architecture of sediments is controlled by a combination of evolving rift basin structure and the glacial climatic cyclicity experienced at the Equatorial Tropics of East Africa during deposition. Rift basin structural styles and subsidence rates are modelled and their merits discussed in light of the field evidence gathered from around the Albertine Rift. After establishing the mechanism of structural development in the basins, the impact of glacially-driven climatic oscillations on sedimentary lithofacies is also incorporated to produce a combined glacial climatic cyclicity model (GCCM) for Albertine Rift basin evolution. This superimposes lake level transgressive – regressive cyclicity upon a tectonic regime of fault propagation and depocentre retreat away from rift margins. The model predicts the resulting stratigraphic architecture that should develop in outcrop areas and is supported by field evidence of not only lithofacies characteristic of arid (glacial) and wet (interglacial) climatic conditions but also cycles of 3-D terrace development, channel incision and sediment backfilling.

Three-dimensional Stacking of Phase Plates for Advanced Electron Beam Shaping.

Tuneable phase plates for free electrons are a highly active area of research. However, their widespread implementation, similar to that of spatial light modulators in light optics, has been hindered by both conceptual and technical challenges. A specific technical challenge involves the need to minimize obstruction of the electron beam by supporting films and electrodes. Here, we describe numerical and analytical mathematical frameworks for three-dimensional stacks of phase plates that can be used to provide near-arbitrary electron beam shaping with minimal obstruction.

Vertical silicon nanowedge formation by repetitive dry and wet anisotropic etching combined with 3D self-aligned sidewall nanopatterning

Three-dimensional (3D) stacking of nano-devices is an effective method for increasing areal density, especially as downscaling of lateral device dimensions becomes impractical. This stacking is mainly achieved through plasma processing of stacked layers on top of a silicon (Si) substrate, which offers process flexibility but poses challenges in obtaining vertical sidewalls without plasma induced damage. A novel wafer-scale fabrication method is presented for realizing sub-200 nm vertically stacked Si nanowedges at the wafer scale, using iterative dry etching, wet anisotropic etching, and thermal oxidation. This approach forms nanowedges by the slow etching {111} Si planes, resulting in smooth surfaces at well-defined angles. A silicon nitride (Si3N4) hard mask is used in an iterative (etch-and-deposit) process, with its thickness determining the number of process iterations. By optimizing etch selectivity during dry etching and/or increasing the initial Si3N4 thickness, the number of process iterations can be increased. The periodicity of the nanowedges can be adjusted by varying the etch time of both dry and wet anisotropic etching. A thin silicon dioxide (SiO2) layer (∼6 nm) is grown on the nanowedges during each iteration. 3D sidewall patterning at the sub-20 nm scale is achieved using corner lithography and local oxidation of Si to selectively open the concave corners. Rhombus-shaped structures are formed at each concave corner after wet anisotropic etching of Si. This novel technology platform will allow for the 3D fabrication of high-density nanodevices for electronic, fluidic, plasmonic, and other applications.

Nano ZnO modified amorphous carbon materials enabling long-cycle performance and high-capacity for lithium/sodium-ion batteries

Zinc-modified carbon materials exhibit high specific capacity, good safety, and low self-discharge, making them promising anode materials for lithium-ion and sodium-ion batteries. However, the high cost of raw materials, complex fabrication processes, and limited cycle life remain significant challenges to their further development. In this study, we elucidated a two-step process, simple in technique and suitable for large-scale production, for in-situ zinc modification of amorphous carbon. The synthesized carbon material exhibited superior reversible specific capacity (maintaining 780.27 mAh·g−1 capacity after 80 cycles at 50 mA·g−1 current density), high cycling stability (maintaining Coulombic efficiency at 100.06 % after 15,000 cycles at 10 A·g−1 current density), and good application value (achieving a capacity of 89.67 mAh·g−1 after 1000 cycles at 200 mA·g−1 current density for the assembled MFAC-Zn || NVP full cell). Through our investigation, we discovered that Nano ZnO not only directly participate in electrochemical reactions but also effectively improve the microstructure of amorphous carbon, increasing its three-dimensional axial stacking and providing more reaction sites. The enrichment of open pores significantly enhances the diffusion efficiency of ions within the carbon-based matrix. The superior diffusion ability of alkali metal-ion in the electrode is the reason for the excellent electrochemical performance of Zinc-modified amorphous carbon. Moreover, the incorporation of Nano ZnO aids in the formation of a robust and thin SEI layer. This significantly enhances the stability of the electrode materials during cycling and improves charge transfer efficiency during the charge-discharge process. Our study provides a new strategy for adjusting the internal microstructure of amorphous carbon materials to achieve high-performance lithium/sodium storage.

Investigating electric heater failure scenarios in solid oxide electrolysis cell systems with a novel three-dimensional dynamic SOEC stack model

Green hydrogen, produced from electrolysis systems powered by zero-emissions renewable energy sources, has the potential to significantly contribute to a sustainable energy future. Performing electrolysis at high temperatures using solid oxide electrolysis cells (SOECs) offers advantages compared to low temperature electrolysis because of significantly higher electrical efficiency, co-electrolysis, and heat integration features. Since the early 2000s, significant efforts have been made to develop SOEC models to investigate the performance characteristics under various operating conditions. This study presents a novel 3-dimensional dynamic SOEC stack model to evaluate system dynamics and control during heater failure scenarios. The study demonstrates that with the implemented control strategies, the changes in the stack temperature gradient are negligible under inlet steam heater failure since the stack heaters are positioned on the same side as the steam entering the stack. On the other hand, when the inlet air heater fails, the temperature gradient increases from 13 °C to 36 °C because the air inlet heater is located on the opposite side of the stack heaters. To overcome stack heater failure scenarios, two potential strategies are investigated: 1) increasing the inlet air temperature and 2) manipulating operating current. Both control strategies are effective. Increasing inlet air temperature does not impact the system efficiency, but increasing the operating current requires an additional 0.67 kWh per kg of H2 produced.

Giant membrane rings/loops in the cytosol of P. falciparum-infected erythrocytes and their relation to the parasite.

Striking morphological transformations characterize the invasion of a red blood cell by the malaria parasite. Shortly after the infection, parasite-induced membranes appear in the cytosol of the affected host erythrocyte. One intensely investigated membrane type, commonly called Maurer's clefts, has a slit-like morphology and can be arranged in the form of extended three-dimensional membrane stacks or networks. Here we report the three-dimensional reconstruction of a second membrane type, giant or extended membrane rings/loops, that have only occasionally been described on single ultrathin sections, however that have never been systematically examined so far. Serial ultrathin sectioning of P. falciparum-infected red blood cells, subsequent three-dimensional reconstructions, and in addition examination of Giemsa-stained blood films revealed that intraerythrocytic membrane rings/loops are not isolated structures but are locally in contact with the parasite. They consist either of the parasitophorous vacuolar membrane alone or contain the parasitophorous vacuolar membrane including the plasma membrane of the parasite and small amounts of parasite cytoplasm. We demonstrate that membrane rings/loops represent surface extensions of the parasite that maybe involved in ring stage parasite formation and Maurer's cleft generation at least in a subset of infected red blood cells.

Direct Writing of SERS Substrates Using Femtosecond Laser Pulses.

Achieving a high-density, repeatable, and uniform distribution of "hotspots" across the entire surface-enhanced Raman scattering (SERS) substrate is a current challenge in facilitating the efficient preparation of large-area SERS substrates. In this study, we aim to produce homogeneous surface-enhanced Raman scattering (SERS) substrates based on the strong interaction between femtosecond laser pulses and a thin film of colloidal gold nanoparticles (AuNPs). The SERS substrate we obtained consists of irregularly shaped and sharp-edged gold nanoparticle aggregates with specially extruding features; meanwhile, a large number of three-dimensional AuNP stacks are produced. The advantages of such configurations lie in the production of a high density of hotspots, which can significantly improve the SERS performance. When the laser fluence is 5.6 mJ/cm2, the substrate exhibits the best SERS enhancement effect, and a strong SERS signal can still be observed when testing the concentration of R6G at 10-8 mol/L. The enhancement factor of such SERS substrates prepared using femtosecond laser direct writing is increased by 3 orders of magnitude compared to the conventional furnace annealing process. Furthermore, the relative standard deviation for the intensities of the SERS signals was measured to be 5.1% over an area of 50 × 50 μm2, indicating a highly homogeneous SERS performance and excellent potential for practical applications.

A 64 × 128 3D-Stacked SPAD Image Sensor for Low-Light Imaging.

Low-light imaging capabilities are in urgent demand in many fields, such as security surveillance, night-time autonomous driving, wilderness rescue, and environmental monitoring. The excellent performance of SPAD devices gives them significant potential for applications in low-light imaging. This article presents a 64 (rows) × 128 (columns) SPAD image sensor designed for low-light imaging. The chip utilizes a three-dimensional stacking architecture and microlens technology, combined with compact gated pixel circuits designed with thick-gate MOS transistors, which further enhance the SPAD's photosensitivity. The configurable digital control circuit allows for the adjustment of exposure time, enabling the sensor to adapt to different lighting conditions. The chip exhibits very low dark noise levels, with an average DCR of 41.5 cps at 2.4 V excess bias voltage. Additionally, it employs a denoising algorithm specifically developed for the SPAD image sensor, achieving two-dimensional grayscale imaging under 6 × 10-4 lux illumination conditions, demonstrating excellent low-light imaging capabilities. The chip designed in this paper fully leverages the performance advantages of SPAD image sensors and holds promise for applications in various fields requiring low-light imaging capabilities.

Morphology, functional groups, and CO2 adsorption performance of Cu2(OH)PO4: Effects of synthesis conditions

Global warming, primarily driven by emissions of greenhouse gases, particularly carbon dioxide, has emerged as a widely acknowledged concern. Hence, the development of novel carbon capture materials with high capacity and low cost holds substantial practical significance. This study investigates the influence of aging time, pH, and copper salt on the synthesis of Cu2(OH)PO4 and its CO2 adsorption performance. Cu2(OH)PO4 adsorbents were synthesized under various aging time, pH, and copper salt conditions, and their morphology and surface functional groups were characterized. Experimental findings indicate that excessively prolonged or abbreviated aging times adversely affect the formation of distinct, discernible lamellar structures within the material. Different pH levels influence the stacking configuration of the lamellae, impacting both their thickness and size. Under acidic conditions, lamellae exhibit dispersed three-dimensional stacking; under neutral conditions, lamellae notably enlarge and demonstrate two-dimensional stacking; at pH 9, lamellae stack three-dimensionally and aggregate. Additionally, the CO2 adsorption performance of Cu2(OH)PO4 adsorbents synthesized with different copper salts varies. By examining the relationship between surface functional group content and CO2 adsorption capacity, we deduced the mechanism by which various synthesis conditions affect both surface functional groups and adsorption capacity. Cu2(OH)PO4 synthesized with a 24 h aging time, pH 7, and CuSO4 as the copper salt exhibits the highest CO2 adsorption capacity, achieving 1.006 mmol/g.

Computer 3D Simulation of Proppant Particles

Proppants are one of the key materials for hydraulic fracturing, whose main role is to support fractures and create a channel through which oil and gas can flow. The nature of proppants is the most talked about feature besides their cost, for example, their sphericity, turbidity, particle size, or strength. The porosity, permeability, and fracture conductivity of proppants in fractures are also the main indicators to measure the performance of them. These indicators are usually obtained through physical experiments. However, experimental results often differ depending on the experimental scheme. Different stacking methods of proppant particles lead to this phenomenon. The nature of proppant particles in fractures varies with the way they accumulate. This paper will start with the microscopic arrangement of proppant particles. Considering the randomness and certainty of three-dimensional particle stacking and arrangement, the Monte Carlo stochastic method and an optimization model were used to conduct three-dimensional computer simulation of proppant particles. This lays an important foundation for revealing the randomness and regularity of the micro arrangement of proppant particles.

Experimental Study on Surface Segregation Law of Three-Dimensional Accumulation Body of Sand and Stone Particles by Binary Mechanism

Sand and stone materials are one of the important raw materials for infrastructure construction. In recent years, natural sand resources have decreased rapidly. In order to protect rivers and DAMS and ecological balance, local governments have increased the control power of natural sand mining, and replacing natural sand with mechanically broken parent rock formation mechanism sand has become an inevitable trend of the industry development. During the crushing process of parent rock, sand particles of different particle size range are produced, and particle segregation occurs in the process of stacking in the yard, which brings great trouble to the calculation of particle grading and material sample detection, and hinders the large-scale application of machine-made sand. In this paper, three-dimensional stacking tests of irregular particles were carried out to identify the particle distribution on the surface of the stack by digital image technology, analyze the relationship between particle size composition of particle mixture and the particle distribution of the accumulation body, and study the distribution law and segregation characteristics of the accumulation body. The experimental results show that the mixture with different coarse particle content will produce the corresponding distribution on the surface of the accumulation body after the accumulation. On the surface of the accretion body, the content of coarse particles is vertically distributed along the height of the accretion body. The content of coarse particles in the lower part of the accretion body is greater than that in the upper part of the accretion body. The overall segregation coefficient on the surface of the pile decreases with the increase of coarse particle content, and the variation is the largest in the lower part of the pile surface with the initial coarse particle content. Based on the test results in this paper, it provides a basis for formulating the sampling and inspection method of machine-made sand, ensuring the quality of machine-made sand and improving the utilization rate of machine-made sand.

Different inhibitory mechanisms of flexible and rigid clay minerals on the transport of microplastics in marine porous media

Colloidal interactions between clay minerals and microplastics (MPs) in high salinity seawater are crucial for determining MP fate in marine environments. Montmorillonite (MMT) forms thin and pliable films that tightly cover MPs, while the thick and rigid lamellae of kaolinite (KLT) have limited contact with MPs, resulting in unstable bonding. However, a small quantity of small-sized KLT can create relatively stable heteroaggregates by embedding into the interstitial spaces of MPs. Both MMT and KLT colloids can decrease the mobility of MPs in seawater-saturated sea sand, but their breakthrough curves (BTCs) show distinct phenomena of "blocking" and "ripening", respectively. The "blocking" phenomenon occurs when flexible MMT adheres to the sand surface, depleting attachment sites quickly and inhibiting the retention of subsequent heteroaggregates of MMT-wrapped MPs. The transport of single MMT also experiences colloid competition for attachment sites, but pre-equilibration experiments reveal no competition between MMT and bare MPs for attachment sites. Instead, the attached MMT provides additional attachment sites for MPs. These results suggest that the wrapping of MPs by MMT plays a dominant role in the "blocking" of cotransport. In contrast, rigid KLT forms a three-dimensional stack on the sand surface, offering more attachment sites for subsequent MPs and heteroaggregates.

Contribution to the world of 3D cell products created by bio 3D printing technology and to the life science field

We have been making 3D tissues consist of cells only, based on the corporate philosophy of "contributing to dramatic advances in medical care through the practical application of innovative 3D cell stacking technology." Currently, in the field of regenerative medicine, we are working toward obtaining approval from the Ministry of Health, Labor and Welfare and commercializing large artificial organs that are made from patients' own cells and have functions such as nerve regeneration, osteochondral regeneration, and blood vessels. On the other hand, this three-dimensional cell stacking technology can be extended to technology for culturing cells in an environment similar to the human body, and is expected to serve as a new methodology for evaluating the effects of new products in various fields on living organisms. Therefore, we are planning a business to provide developers of pharmaceuticals, foods, cosmetics, etc. with a small device called "Functional Cell Device (FCD)" that reproduces some of the functions of human organs outside the body. As the first step, we have developed a three-dimensional liver construct (3D mini-liver). The in vitro human liver model has a wide range of usage, such as evaluation of hepatotoxicity of drugs, elucidation of drug metabolism mechanism, and model of liver disease. In this report, we will outline it together with actual examples in regenerative medicine.

Integrating full fan morphology and configuration in three-dimensional simulation of air-cooled proton exchange membrane fuel cell stack

The internal water and thermal state and performance of an air-cooled proton exchange membrane (PEM) fuel cell stack are strongly determined by the fan arrangement and operational characteristics. This study presents an innovative method to investigate the influence of fan on stack performance through integration of fan’s full morphology, including the fan blade, grill between the fan and stack, etc. into a three-dimensional (3D) multiphase stack model. The multiple reference frame (MRF) model is implemented to simulate the air flow field caused by the rotation of fan and the multiple transfers coupled with electrochemical reactions is considered in the 3D stack model in detail. Through this integrated model, the influence of the air supply mode, fan number and duty ratio on stack performance and the distribution characteristics are investigated in detail. It is found that the air flowing into each cell in the fan-cooled stack is highly non-uniform, which increases the variations of oxygen concentration, temperature, and voltage in the stack. In comparison with the blowing mode, the suction mode helps to promote the uniformity of air supply with a lower air flow velocity.

Low Stress TSV Arrays for High-Density Interconnection

In three-dimensional (3D) stacking, the thermal stress of through-silicon via (TSV) has a significant influence on chip performance and reliability, and this problem is exacerbated in high-density TSV arrays. In this study, a novel hollow tungsten TSV (W–TSV) is presented and developed. The hollow structure provides space for the release of thermal stress. Simulation results showed that the hollow W–TSV structure can release 60.3% of thermal stress within the top 2 μm from the surface, and thermal stress can be decreased to less than 20 MPa in the radial area of 3 μm. The ultra-high-density (1600 TSV∙mm−2) TSV array with a size of 640 × 512, a pitch of 25 μm, and an aspect ratio of 20.3 was fabricated, and the test results demonstrated that the proposed TSV has excellent electrical and reliability performances. The average resistance of the TSV was 1.21 Ω. The leakage current was 643 pA and the breakdown voltage was greater than 100 V. The resistance change is less than 2% after 100 temperature cycles from −40 to 125 °C. Raman spectroscopy showed that the maximum stress on the wafer surface caused by the hollow W–TSV was 31.02 MPa, which means that there was no keep-out zone (KOZ) caused by the TSV array. These results indicate that this structure has great potential for applications in large-array photodetectors and 3D integrated circuits.

Numerical investigation of air flow characteristics for a compact 5 [formula omitted] 10 array tubular segmented-in-series solid oxide fuel cell stack

Tubular segmented-in-series solid oxide fuel cells (SIS-SOFCs) offer the advantages of high voltage, low current, easy sealing, and high thermal shock resistance. Tubular SIS-SOFCs can be assembled into a highly integrated power-generation stack module to increase the volumetric power density. This study investigated the air flow characteristics of a kilowatt-class tubular SIS-SOFC stack with a 5 × 10-cell array, each containing 59 segments. A three-dimensional stack model that considers practical stack structures, coupled electrochemical reactions, and the mass/momentum/heat transfer processes was developed. The results show that a large flow nonuniformity existed in the conventional tubular stack design, which resulted in a severe temperature distribution. Local hot spots at the marginal positions and circumferential temperature difference were found to be non-negligible. To improve the flow uniformity, an air distributor with optimized diameters at different positions was designed, and manifold parameters were adjusted to balance the flow resistance. The maximum temperature was reduced by 35 K and temperature uniformity was significantly improved.

Mechanical characterizations of η′-Cu6(Sn, In)5 intermetallic compound solder joint: Getting prepared for future nanobumps

As advanced silicon manufacturing processes slow down in scaling, three-dimensional stacking of chips has become a future trend in microelectronic industry. High-density bonding technology is one of the core technologies used to achieve the stacking. In this work, we explored a new bonding technology that is possible to manufacture future high-density interconnects. We fabricated a series of sandwich structure solder joints with different thicknesses using SnBiIn-based nanoparticles under a low bonding temperature of 100 °C. The intermetallic compound (IMC) at the interface is proven to be η′-Cu6(Sn, In)5 nanocrystals with random grain orientations through X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and atomic probe tomography (APT). The hardness and elastic modulus of η′-Cu6(Sn, In)5 were measured to be 4.093 GPa and 79.586 GPa by micropillar compression tests, respectively, decreasing by 35% and 29.1% compared to Cu6Sn5. Therefore, doping In atoms reduces the brittleness of IMCs, providing a new approach for mitigating the mechanical failures of full IMC bump. First-principles calculation also verified the change in mechanical properties. Furthermore, a full-Cux(Sn, In)y IMCs solder joint and an array of 3 μm solder joints were fabricated experimentally using the bonding technology. This technology successfully demonstrates a pioneer interconnection bonding methodology for future ultra-high-density chip stacking using low melting point solder nanoparticles.

Implicit neural representations in light microscopy.

Three-dimensional stacks acquired with confocal or two-photon microscopy are crucial for studying neuroanatomy. However, high-resolution image stacks acquired at multiple depths are time-consuming and susceptible to photobleaching. In vivo microscopy is further prone to motion artifacts. In this work, we suggest that deep neural networks with sine activation functions encoding implicit neural representations (SIRENs) are suitable for predicting intermediate planes and correcting motion artifacts, addressing the aforementioned shortcomings. We show that we can accurately estimate intermediate planes across multiple micrometers and fully automatically and unsupervised estimate a motion-corrected denoised picture. We show that noise statistics can be affected by SIRENs, however, rescued by a downstream denoising neural network, shown exemplarily with the recovery of dendritic spines. We believe that the application of these technologies will facilitate more efficient acquisition and superior post-processing in the future.

Simple-Structured Acceptor with Highly Interconnected Electron-Transport Pathway Enables High-Efficiency Organic Solar Cells.

Achieving desirable charge-transport highway is of vital importance for high-performance organic solar cells (OSCs). Here, it is shown how molecular packing arrangements can be regulated via tuning the alkyl-chain topology, thus resulting in a 3D network stacking and highly interconnected pathway for electron transport in a simple-structured nonfused-ring electron acceptor (NFREA) with branched alkyl side-chains. As a result, a record-breaking power conversion efficiency of 17.38% (certificated 16.59%) is achieved for NFREA-based devices, thus providing an opportunity for constructing low-cost and high-efficiency OSCs.

An Efficient and Fast Method for Labeling and Analyzing Mouse Glomeruli.

The glomeruli are fundamental units in the kidney; hence, studying the glomeruli is pivotal for understanding renal function and pathology. Biological imaging provides intuitive information; thus, it is of great significance to label and observe the glomeruli. However, the glomeruli observation methods currently in use require complicated operations, and the results may lose label details or three-dimensional (3D) information. The clear, unobstructed brain imaging cocktails and computational analysis (CUBIC) tissue clearing technology has been widely used in renal research, allowing for more accurate detection and deeper detection depth. We found that mouse glomeruli can be rapidly and effectively labeled by tail vein injection of medium molecular weight FITC-Dextran followed by the CUBIC clearing method. The cleared mouse kidney could be scanned by a light-sheet microscope (or a confocal microscope when sliced) to obtain three-dimensional image stacks of all the glomeruli in the entire kidney. Processed with appropriate software, the glomeruli signals could be easily digitized and further analyzed to measure the number, volume, and frequency of the glomeruli.