Three-dimensional Systems Research Articles

Enteric neurospheres retain the capacity to assemble neural networks with motile and metamorphic gliocytes and ganglia

BackgroundNeurosphere medium (NSM) and self-renewal medium (SRM) were widely used to isolate enteric neural stem cells (ENSCs) in the form of neurospheres. ENSCs or their neurosphere forms were neurogenic and gliogenic, but the compelling evidence for their capacity of assembling enteric neural networks remained lacking, raising the question of their aptitude for rebuilding the enteric nervous system (ENS) in ENSC therapeutics. It prompted us to explore an effective culture protocol or strategy for assembling ENS networks, which might also be employed as an in vitro model to simplify the biological complexity of ENS embedded in gut walls.MethodsNSM and SRM were examined for their capacity to generate neurospheres in mass culture of dispersed murine fetal enterocytes at serially diluted doses and assemble enteric neural networks in two- and three-dimensional cell culture systems and ex vivo on gut explants. Time-lapse microphotography was employed to capture cell activities of assembled neural networks. Neurosphere transplantation was performed via rectal submucosal injection.ResultsIn mass culture of dispersed enterocytes, NSM generated discrete units of neurospheres, whereas SRM promoted neural network assembly with neurospheres akin to enteric ganglia. Both were highly affected by seeding cell doses. SRM had similar ENSC mitosis-driving capacity to NSM, but was superior in driving ENSC differentiation in company with heightened ENSC apoptosis. Enteric neurospheres were motile, capable of merging together. It argued against their clonal entities. When nurtured in SRM, enteric neurospheres proved competent to assemble neural networks on two-dimensional coverslips, in three-dimensional hydrogels and on gut explants. In the course of neural network assembly from enteric neurospheres, neurite extension was preceded by migratory expansion of gliocytes. Assembled neural networks contained motile ganglia and gliocytes that constantly underwent shapeshift. Neurospheres transplanted into rectal submucosa might reconstitute myenteric plexuses of recipients’ rectum.ConclusionEnteric neurospheres mass-produced in NSM might assemble neural networks in SRM-immersed two- or three-dimensional environments and on gut explants, and reconstitute myenteric plexuses of the colon after rectal submucosal transplantation. Our results also shed first light on the dynamic entity of ENS and open the experimental avenues to explore cellular activities of ENS and facilitate ENS demystification.

3D Models of Sarcomas: The Next-generation Tool for Personalized Medicine.

Sarcoma is a complex and heterogeneous cancer that has been difficult to study in vitro. While two-dimensional (2D) cell cultures and mouse models have been the dominant research tools, three-dimensional (3D) culture systems such as organoids have emerged as promising alternatives. In this review, we discuss recent developments in sarcoma organoid culture, with a focus on their potential as tools for drug screening and biobanking. We also highlight the ways in which sarcoma organoids have been used to investigate the mechanisms of gene regulation, drug resistance, metastasis, and immune interactions. Sarcoma organoids have shown to retain characteristics of in vivo biology within an in vitro system, making them a more representative model for sarcoma research. Our review suggests that sarcoma organoids offer a potential path forward for translational research in this field and may provide a platform for developing personalized therapies for sarcoma patients.

Enhancing surgical precision and efficiency: a study and comparison of a three-dimensional surgical video system in proliferative diabetic retinopathy surgery.

This study aimed to investigate the safety and efficacy of three-dimensional (3D) surgical video systems for proliferative diabetic retinopathy (PDR). This retrospective clinical case study included 30 patients (30 eyes) with PDR. Patients were divided into two groups: one underwent surgery using a 3D surgical video system (14 cases, 14 eyes), while the other underwent traditional microscope surgery (16 cases, 16 eyes). Safety and efficacy were assessed through predetermined surgical parameters, including surgical duration, intraoperative membrane removal rate, and occurrences during intraoperative and postoperative phases. Our study revealed noteworthy differences in various aspects between the 3D surgical video system group and the traditional microscope surgery group. Specifically, the mean surgical time was 30.25 ± 14.43 mins in the 3D surgical video system group, while it was 38.56 ± 18.71 mins in the traditional microscope surgery group (p = 0.051). Furthermore, the mean membrane removal time was significantly shorter in the 3D group at 2.53 ± 1.52 mins, as compared to 3.23 ± 1.76 mins in the traditional group (p = 0.042). Importantly, the membrane removal rate also displayed a significant difference, with the 3D group at 0.55 ± 0.07 and the traditional group at 0.41 ± 0.11 (p = 0.018). However, no notable differences were observed between the two groups in terms of intraoperative and postoperative incidences. The safety and efficacy obtained using the 3D surgical video system in PDR surgery were comparable to those obtained in traditional microscopic surgery.

Vibration Control for a Three-Dimensional Variable Length Flexible String With Time-Varying Actuator Faults and Unknown Control Directions

In this study, actuator faults and unknown control directions are taken into account concurrently for a three-dimensional variable length flexible string system modeled by partial differential equations (PDEs). Different from the unknown fault parameters being restricted to just positive constants in the previous fault-tolerance research on PDEs systems, the time-varying actuator faults are considered, which is more practical but challenging. Additionally, the control directions of the system are unknown which can also be different in three directions. To overcome the difficulties, adaptive control laws employing the Nussbaum function are designed, and some auxiliary control signals are intended for service. Under the proposed boundary control scheme, uniform ultimate boundedness of the closed-loop system is guaranteed, and the deflections of the flexible string can be suppressed to a small neighborhood of zero. Finally, the simulations are implemented to indicate the control effect. <i>Note to Practitioners</i>&#x2014;String structural systems are widely used in fields of indoor and outdoor industrial and mining enterprises, ports, wharves, and seabeds. To improve work efficiency and safety, effectively suppressing the vibration of the flexible string is a crucial problem to be solved. This paper proposes a novel adaptive boundary control scheme to reduce the deflections of the flexible string system subject to time-varying actuator faults and unknown control directions in three-dimensional space. The control scheme is designed without simplification, which can provide a theoretical basis and a feasible solution for the control of flexible string systems in practical engineering. In the future, we will address the modeling and control problems of moving three-dimensional variable length flexible string systems.

Optimizing the combination of data-driven and model-based elements in hybrid reservoir computing.

Hybrid reservoir computing combines purely data-driven machine learning predictions with a physical model to improve the forecasting of complex systems. In this study, we investigate in detail the predictive capabilities of three different architectures for hybrid reservoir computing: the input hybrid (IH), output hybrid (OH), and full hybrid (FH), which combines IH and OH. By using nine different three-dimensional chaotic model systems and the high-dimensional spatiotemporal chaotic Kuramoto-Sivashinsky system, we demonstrate that all hybrid reservoir computing approaches significantly improve the prediction results, provided that the model is sufficiently accurate. For accurate models, we find that the OH and FH results are equivalent and significantly outperform the IH results, especially for smaller reservoir sizes. For totally inaccurate models, the predictive capabilities of IH and FH may decrease drastically, while the OH architecture remains as accurate as the purely data-driven results. Furthermore, OH allows for the separation of the reservoir and the model contributions to the output predictions. This enables an interpretation of the roles played by the data-driven and model-based elements in output hybrid reservoir computing, resulting in higher explainability of the prediction results. Overall, our findings suggest that the OH approach is the most favorable architecture for hybrid reservoir computing, when taking accuracy, interpretability, robustness to model error, and simplicity into account.

Review of Three-Dimensional Handheld Photoacoustic and Ultrasound Imaging Systems and Their Applications.

Photoacoustic (PA) imaging is a non-invasive biomedical imaging technique that combines the benefits of optics and acoustics to provide high-resolution structural and functional information. This review highlights the emergence of three-dimensional handheld PA imaging systems as a promising approach for various biomedical applications. These systems are classified into four techniques: direct imaging with 2D ultrasound (US) arrays, mechanical-scanning-based imaging with 1D US arrays, mirror-scanning-based imaging, and freehand-scanning-based imaging. A comprehensive overview of recent research in each imaging technique is provided, and potential solutions for system limitations are discussed. This review will serve as a valuable resource for researchers and practitioners interested in advancements and opportunities in three-dimensional handheld PA imaging technology.

Advancing Towards Physiologically Relevant Models of the Brain: Three-Dimensional Human Induced Pluripotent Stem Cell (hiPSC)-Based Cell Culture Systems in Neuroscience

One of the biggest challenges in the field of neurological disorders is the limited availability of freshly dissected human brain tissue. Therefore, the use of human induced pluripotent stem cells (hiPSCs) is important to develop human brain-like models to study the interaction of different brain cell types in health and disease. For physiologically relevant disease modeling, three-dimensional (3D) cell culture systems are of great importance because they provide a more representative in vivo-like micro-environment to the cells. The field of 3D cell culture systems using diverse hiPSC-derived cells is growing and gets steadily advanced. However, to this day, there is no cell culture model available that includes all brain cell types. Here, we review the latest improvements of 3D hiPSC-based cell culture systems in the field of neuroscience. We focus on innovations for the generation of neurons, astrocytes, oligodendrocytes, microglia as well as endothelial cells and pericytes.

Synergistic Therapeutic Potential of Dual 3D Mesenchymal Stem Cell Therapy in an Ischemic Hind Limb Mouse Model.

Three-dimensional (3D) culture systems have been widely used to promote the viability and metabolic activity of mesenchymal stem cells (MSCs). The aim of this study was to explore the synergistic benefits of using dual 3D MSC culture systems to promote vascular regeneration and enhance therapeutic potential. We used various experimental assays, including dual 3D cultures of human adipose MSCs (hASCs), quantitative reverse transcription polymerase chain reaction (qRT-PCR), in vitro cell migration, Matrigel tube network formation, Matrigel plug assay, therapeutic assays using an ischemic hind limb mouse model, and immunohistochemical analysis. Our qRT-PCR results revealed that fibroblast growth factor 2 (FGF-2), granulocyte chemotactic protein-2 (GCP-2), and vascular endothelial growth factor-A (VEGF-A) were highly upregulated in conventional 3D-cultured hASCs (ASC-3D) than in two-dimensional (2D)-cultured hASCs. Hepatocyte growth factor (HGF), insulin-like growth factor-1 (IGF-1), and stromal-cell-derived factor-1 (SDF-1) showed higher expression levels in cytokine-cocktail-based, 3D-cultured hASCs (ASC-3Dc). A conditioned medium (CM) mixture of dual 3D ASCs (D-3D; ASC-3D + ASC-3Dc) resulted in higher migration and Matrigel tube formation than the CM of single 3D ASCs (S-3D; ASC-3D). Matrigel plugs containing D-3D contained more red blood cells than those containing S-3D. D-3D transplantation into ischemic mouse hind limbs prevented limb loss and augmented blood perfusion when compared to S-3D transplantation. Transplanted D-3D also revealed a high capillary density and angiogenic cytokine levels and transdifferentiated into endothelial-like cells in the hind limb muscle. These findings highlight the benefits of using the dual 3D culture system to optimize stem-cell-based therapeutic strategies, thereby advancing the therapeutic strategy for ischemic vascular disease and tissue regeneration.

Synchronization of chaotic satellite systems with an unknown parameter

Spacecraft (satellite) formation has several applications in space exploration. Synchronization controllers are essential in satellite formation systems. This article proposes a novel robust adaptive synchronization control (RASC) technique for two identical three-dimensional chaotic satellite systems attitude synchronization with an unknown system parameter, unknown bounded model uncertainties, unknown external disturbances, and nonlinear terms. This controller achieves smooth error vector convergence to zero. The closed-loop has a robust performance as the controller avoids plant nonlinear terms cancellation. This controller has two parts. (i) A nonlinear controller for keeping the closed-loop stable; it flourishes robust and faster error vector convergence to zero with reduced fluctuations. (ii) An adaptive nonlinear controller that compensates exogenous disturbances and model uncertainties using online estimations of model uncertainties and bounds. The Lyapunov stability theory assures the closed-loop's global asymptotic robust stability. Computer simulation results-based analysis verifies the theoretical findings. The article includes a comparative study and discusses the control effort saturation effects.

Three-Dimensional Scaffolds for Intestinal Cell Culture: Fabrication, Utilization, and Prospects.

The intestine is a visceral organ that integrates absorption, metabolism, and immunity, which is vulnerable to external stimulus. Researchers in the fields such as food science, immunology, and pharmacology have committed to developing appropriate in vitro intestinal cell models to study the intestinal absorption and metabolism mechanisms of various nutrients and drugs, or pathogenesis of intestinal diseases. In the past three decades, the intestinal cell models have undergone a significant transformation from conventional two-dimensional cultures to three-dimensional (3D) systems, and the achievements of 3D cell culture have been greatly contributed by the fabrication of different scaffolds. In this review, we first introduce the developing trend of existing intestinal models. Then, four types of scaffolds, including Transwell, hydrogel, tubular scaffolds, and intestine-on-a-chip, are discussed for their 3D structure, composition, advantages, and limitations in the establishment of intestinal cell models. Excitingly, some of the in vitro intestinal cell models based on these scaffolds could successfully mimic the 3D structure, microenvironment, mechanical peristalsis, fluid system, signaling gradients, or other important aspects of the original human intestine. Furthermore, we discuss the potential applications of the intestinal cell models in drug screening, disease modeling, and even regenerative repair of intestinal tissues. This review presents an overview of state-of-the-art scaffold-based cell models within the context of intestines, and highlights their major advances and applications contributing to a better knowledge of intestinal diseases. Impact statement The intestine tract is crucial in the absorption and metabolism of nutrients and drugs, as well as immune responses against external pathogens or antigens in a complex microenvironment. The appropriate experimental cell model in vitro is needed for in-depth studies of intestines, due to the limitation of animal models in dynamic control and real-time assessment of key intestinal physiological and pathological processes, as well as the "R" principles in laboratory animal experiments. Three-dimensional (3D) scaffold-based cell cultivation has become a developing tendency because of the superior cell proliferation and differentiation and more physiologically relevant environment supported by the customized 3D scaffolds. In this review, we summarize four types of up-to-date 3D cell culture scaffolds fabricated by various materials and techniques for a better recapitulation of some essential physiological and functional characteristics of original intestines compared to conventional cell models. These emerging 3D intestinal models have shown promising results in not only evaluating the pharmacokinetic characteristics, security, and effectiveness of drugs, but also studying the pathological mechanisms of intestinal diseases at cellular and molecular levels. Importantly, the weakness of the representative 3D models for intestines is also discussed.

A fast algorithm for decoding an object image in structured light for measuring a three-dimensional profi le in a non-linear optical path

The work is devoted to the development of image processing algorithms for measuring a three-dimensional surface profi le using phase triangulation methods. An algorithm for decoding images of an object in structured light is proposed, based on an iterative search for the minimum deviation of the model function from the measurement results and compensating for the nonlinearity of the receiving-transmitting path of the measuring complex. A distinctive feature of the proposed method is that the search for the model function is sought in the form of a polynomial of the second degree, which ensures the stability of the method against nonlinear distortions caused by power-law transformations of the receiving-transmitting path. The use of the interval search method as part of the proposed algorithm provides a qualitative reduction in its algorithmic complexity. It is shown that the proposed algorithm provides a stable search for the value of the initial phase shift in object images, is resistant to noise and non-linear distortions. The algorithm proposed in the paper can be used to process images received in three-dimensional scanning systems based on triangulation methods using structured illumination and phase triangulation. The proposed algorithm will be especially useful for data processing during the operation of measuring systems in the conditions of a nonlinear source-receiver path of optical radiation and measurement time limitations.

Radiation exposure in spine surgeries

Radiation exposure is a significant concern in spine surgeries due to the extensive use of fluoroscopic imaging. This review aims to evaluate the risks, consequences, and prevention strategies associated with radiation exposure in spine surgeries. The risks of radiation exposure include potential biological damage to patients and surgical staff, such as skin burns, cataracts, and an increased risk of developing cancer. The consequences of radiation exposure can have long-term health implications and may result in substantial healthcare costs. To mitigate the risks, various prevention strategies are recommended. These include optimizing the use of fluoroscopy by adopting low-dose imaging techniques, minimizing the duration of exposure, and ensuring proper shielding of personnel. Additionally, the use of alternative imaging modalities, such as intraoperative three-dimensional (3D) navigation systems, can reduce reliance on fluoroscopy and subsequently decrease radiation exposure. Furthermore, implementing a culture of radiation safety through education, training, and awareness programs is crucial. This involves educating surgeons, nurses, and other healthcare professionals about the potential risks, proper use of equipment, and radiation protection measures. Strict adherence to radiation safety guidelines and continuous monitoring of radiation doses are essential to ensure the well-being of both patients and healthcare providers. In short, radiation exposure in spine surgeries poses significant risks and potential consequences. However, with the adoption of appropriate prevention strategies, such as optimizing imaging techniques, implementing alternative modalities, and fostering a culture of radiation safety, the potential risks can be mitigated. By prioritizing radiation safety, healthcare facilities can provide better outcomes for patients and minimize the long-term health implications associated with radiation exposure in spine surgeries.

Factors Affecting Stem Cell-Based Regenerative Approaches in Retinal Degeneration.

Inherited and age-associated vision loss is often associated with degeneration of the cells of the retina, the light-sensitive layer at the back of the eye. The mammalian retina, being a postmitotic neural tissue, does not have the capacity to repair itself through endogenous regeneration. There has been considerable excitement for the development of cell replacement approaches since the isolation and development of culture methods for human pluripotent stem cells, as well as the generation of induced pluripotent stem cells. This has now been combined with novel three-dimensional organoid culture systems that closely mimic human retinal development in vitro. In this review, we cover the current state of the field, with emphasis on the cell delivery challenges, role of the recipient immunological microenvironment, and challenges related to connectivity between transplanted cells and host circuitry both locally and centrally to the different areas of the brain.

Embedded Living HER2+ Cells in a 3D Gelatin-Alginate Hydrogel as an In Vitro Model for Immunotherapy Delivery for Breast Cancer.

Epidermal growth factor receptor 2 (HER2) is the second target molecule most commonly used in breast cancer treatment. Both recurrence and metastasis are still deadly for HER2+ breast cancer patients. Hydrogels can be an option for developing three-dimensional (3D) cell culture systems that resemble tumor features better than monolayer cultures and could be used for preclinical screening for new biotherapeutics. Biopolymers (gelatin and alginate) were used to develop a hydrogel capable of encapsulating living HER2+ breast cancer cells BT-474/GFP. The hydrogel was physicochemically characterized, and the viability of embedded cells was evaluated. The hydrogel developed had suitable physical properties, with swelling of 38% of its original mass at 20 h capacity and pore sizes between 20 and 125 µm that allowed cells to maintain their morphology in a 3D environment, in addition to being biocompatible and preserving 90% of cell viability at 10 days. Furthermore, encapsulated BT-474/GFP cells maintained HER2 expression that could be detected by the Trastuzumab-fluorescent antibody, so this hydrogel could be used to evaluate new HER2-targeted therapies.

Gelatin-based 3D biomimetic scaffolds platform potentiates culture of cancer stem cells in esophageal squamous cell carcinoma

Cancer stem cells (CSCs) are crucial for tumorigenesis, metastasis, and therapy resistance in esophageal squamous cell carcinoma (ESCC). To further elucidate the mechanism underlying characteristics of CSCs and develop CSCs-targeted therapy, an efficient culture system that could expand and maintain CSCs is needed. CSCs reside in a complex tumor microenvironment, and three-dimensional (3D) culture systems of biomimetic scaffolds are expected to better support the growth of CSCs by recapitulating the biophysical properties of the extracellular matrix (ECM). Here, we established gelatin-based 3D biomimetic scaffolds mimicking the stiffness and collagen content of ESCC, which could enrich ESCC CSCs efficiently. Biological changes of ESCC cells laden in scaffolds with three different viscoelasticity emulating physiological stiffness of esophageal tissues were thoroughly investigated in varied aspects such as cell morphology, viability, cell phenotype markers, and transcriptomic profiling. The results demonstrated the priming effects of viscoelasticity on the stemness of ESCC. The highly viscous scaffolds (G’: 6–403 Pa; G’’: 2–75 Pa) better supported the enrichment of ESCC CSCs, and the TGF-beta signaling pathway might be involved in regulating the stemness of ESCC cells. Compared to two-dimensional (2D) cultures, highly viscous scaffolds significantly promoted the clonal expansion of ESCC cells in vitro and tumor formation ability in vivo. Our findings highlight the crucial role of biomaterials’ viscoelasticity for the 3D culture of ESCC CSCs in vitro, and this newly-established culture system represents a valuable platform to support their growth, which could facilitate the CSCs-targeted therapy in the future.

Development of a novel three-dimensional biofilm-electrode system (3D-BES) loaded with Fe-modified biochars for enhanced pollutants removal in landfill leachate

Different mass ratio iron (Fe)-loaded biochars (FeBCs) were prepared from food waste and used in the three-dimensional biofilm-electrode systems (3D-BES) as particular electrodes for landfill leachate treatment. Compared to the unmodified biochar (BC), specific surface area of Fe-loaded biochars (FeBC-3 with a Fe: biochar of 0.2:1) increased from 63.01 m2/g to 184.14 m2/g, and pore capacity increased from 0.038 cm3/g to 0.111 cm3/g. FeBCs provided more oxygen-containing functional groups and exhibited excellent redox properties. Installed with FeBC-3 as particular electrode, both NH4+-N and chemical oxygen demand COD removals in 3D-BESs were well fitted with the pseudo-first-order model, with the maximum removal efficiencies of 98.6 % and 95.5 %, respectively. The batch adsorption kinetics experiments confirmed that the maximum NH4+-N (7.5 mg/g) and COD (21.8 mg/g) adsorption capacities were associated closely with the FeBC-3 biochar. In contrast to the 3D-BES with the unmodified biochar, Fe-loaded biochars significantly increased the abundance of microorganisms being capable of removing organics and ammonia. Meanwhile, the increased content of dehydrogenase (DHA) and electron transport system activity (ETSA) evidenced that FeBCs could enhance microbial internal activities and regulate electron transfer process among functional microorganisms. Consequently, it is concluded that Fe-loaded biochar to 3D-BES is effective in enhancing pollutant removals in landfill leachate and provided a reliable and effective strategy for refractory wastewater treatment.

Cellular and molecular antiproliferative effects in 2D monolayer and 3D-cultivated HT-29 cells treated with zerumbone.

Zerumbone (ZER) is a phytochemical isolated from plants of the Zingiberaceae family. Numerous studies have demonstrated its diverse pharmacological properties, particularly its potent antitumorigenic activity. This study aimed to assess the antiproliferative effects of ZER on HT-29 cells cultivated in both two-dimensional (2D) monolayer and three-dimensional (3D) spheroid culture systems. The evaluation of growth (size), cell death, and cell cycle arrest in 3D spheroid HT-29 cells was correlated with mRNA expression data. Treatment of 2D cells revealed that ZER exhibited cytotoxicity at concentrations above 30 µM, and an IC50 of 83.54 µM (24-h post-ZER treatment) effectively suppressed cell migration. In the 3D model, ZER induced an increase in spheroid volume over a 72-h period attributed to disaggregation and reconfiguration of characteristic zones. Analysis of cell death demonstrated a significant rise in apoptotic cells after 24 h of ZER treatment, along with cell cycle arrest in the G1 phase. Furthermore, ZER treatment resulted in alterations in mRNA expression, affecting key signaling pathways involved in cell death (BCL2 and BBC3), endoplasmic reticulum stress (ERN1), DNA damage (GADD45A), cell cycle regulation (CDKN1A, NFKB1, MYC, and TP53), and autophagy (BECN1 and SQSTM1). These findings suggested that ZER holds promise as a potential candidate for the development of novel anticancer agents that can modulate crucial cell signaling pathways. Additionally, the use of the 3D culture system proved to be a valuable tool in our investigation.

Dynamics of 3D Slender Blocks: A Mathematical Model

The dynamics of three-dimensional (3D) slender systems such as statues, obelisks, monuments, museums, and household objects are highly nonlinear. In this study, a numerical model for rigid blocks in 3D, referred to as the physical model (PM), is developed to explore and view the motion of the slender blocks to base excitations. The model can represent the dynamics of both symmetric and mass-eccentric 3D blocks for unidirectional and bidirectional excitations. Keeping the kinematics of the system in view, the PM is developed as an assemblage of different subsystems in the Simscape Multibody Library. The rigid block supported by four tiny spheres at the corners is resting on a rigid table. Physical interaction between the table and the rigid body is simulated by introducing a virtual plane characterized by a spring and a damper that follows the visco-elastic Kelvin model. The values of the depth of the virtual plane, parameters of the Kelvin model, and the dimension of the tiny spheres are suitably chosen for such interaction. Adequately large values for kinetic and static friction are used in the virtual plane to prevent the body from sliding during its rocking motion. The motion of the table is described by choosing the inertial reference frame with origin at a fixed point and another parallel frame fixed with the tabletop. The response of the rigid body is described by the asymmetric Euler sequence. A third set of the frame, i.e. the body-fixed reference with the origin at the centre of mass of the corresponding symmetric body is introduced by a Bushing joint. A calculated amount of mass-eccentricity is generated by adding very small square blocks to the side-faces of the 3D symmetric block. The response of mass eccentric systems to trigonometric base excitations applied in-plane and out-of-plane of the eccentricity is computed using the PM, and a comparison of the same to the results derived analytically confirms the adequacy of the model. In the sequel, representative case studies are presented and interpreted to uncover the complex dynamics of the mass eccentric rocking systems. The PM can also serve as the basis of analyzing and viewing the motion of blocks with arbitrary geometry.

Magnetic force-based cell manipulation for in vitro tissue engineering.

Cell manipulation techniques such as those based on three-dimensional (3D) bioprinting and microfluidic systems have recently been developed to reconstruct complex 3D tissue structures in vitro. Compared to these technologies, magnetic force-based cell manipulation is a simpler, scaffold- and label-free method that minimally affects cell viability and can rapidly manipulate cells into 3D tissue constructs. As such, there is increasing interest in leveraging this technology for cell assembly in tissue engineering. Cell manipulation using magnetic forces primarily involves two key approaches. The first method, positive magnetophoresis, uses magnetic nanoparticles (MNPs) which are either attached to the cell surface or integrated within the cell. These MNPs enable the deliberate positioning of cells into designated configurations when an external magnetic field is applied. The second method, known as negative magnetophoresis, manipulates diamagnetic entities, such as cells, in a paramagnetic environment using an external magnetic field. Unlike the first method, this technique does not require the use of MNPs for cell manipulation. Instead, it leverages the magnetic field and the motion of paramagnetic agents like paramagnetic salts (Gadobutrol, MnCl2, etc.) to propel cells toward the field minimum, resulting in the assembly of cells into the desired geometrical arrangement. In this Review, we will first describe the major approaches used to assemble cells in vitro-3D bioprinting and microfluidics-based platforms-and then discuss the use of magnetic forces for cell manipulation. Finally, we will highlight recent research in which these magnetic force-based approaches have been applied and outline challenges to mature this technology for in vitro tissue engineering.

Nuclear Quantum Dynamics of Three-Dimensional Condensed-Phase Systems by Constant Uncertainty Molecular Dynamics.

Constant uncertainty molecular dynamics (CUMD), which was developed to include nuclear quantum effects (NQEs) in molecular dynamics (MD) simulations, is extended to three-dimensional condensed-phase systems. Its applicability was verified via CUMD simulations of bulk water and ice Ih with the q-TIP4P/F potential model. The simulated radial distribution functions, proton momentum distributions, and infrared spectra were compared with those of previous studies in which the simulations were carried out on the basis of the imaginary-time path-integral formalism. We found that CUMD can function as an alternative trajectory-based simulation method for including static and dynamic NQEs in MD simulations of three-dimensional condensed-phase systems.