3D Engine Research Articles

Model predictive control for a multiple injection combustion model

Abstract In this work, a model predictive controller is developed for a multiple injection combustion model. A 1D engine model with three distinct injections is used to generate data for identifying the state-space representation of the engine model. This state-space model is then used to design a controller for controlling the start of injection and injected fuel mass of the post injection. These parameters are used as inputs for the engine model to control the maximum cylinder pressure and indicated mean effective pressure.

Digital Training Platform for Comprehensive Traffic Simulation

The paper deals with the development of software for traffic flow simulation combining the widest spectrum of mathematical approaches used in this field. Macro- and microscopic models, models of cellular automata as well as different numerical methods of their computer implementation are incorporated into a digital platform. Original developments of the authors of the paper such as quasi-gas dynamic traffic model and multilane cellular automata model take the main place. Potential users of the software are students and researchers. The platform possesses an intuitive graphical interface ensuring interactivity. Microsoft Visual Studio with C# is chosen as the development environment, the Unity 3D engine is employed for visualization and collaboration with WinForm projects. In the future, the platform can be transformed into a network computer laboratory providing access to information resources via Internet.

A three-dimensional intelligent engineering management and control system for the construction of a long-span valve hall project based on a microservice architecture.

Three-dimensional intelligent engineering management and control systems (EMCS) based on the browser/server (B/S) model are an important part of intelligent engineering development. These systems are used for solving the difficulties encountered in engineering management with frequent cross-specialties and are vital tools for data exchange and service sharing among multiple departments. Currently, most engineering management and control systems are based on service-oriented architectures (SOAs). The integration mechanism and high coupling of SOAs leads to the reduction in system expansibility, service quality and service safety of the engineering system, making it difficult for these architectures to serve the construction of long-span valve hall engineering. To address these concerns, the management and application technology of the multidisciplinary data of valve hall engineering based on a microservice architecture (MSA) is proposed to improve the management efficiency of engineering data. A 3D integration modeling method for valve hall engineering structures and geological environments is proposed to establish the topological association between engineering structures and geological environments, without increasing the amount of model data required. A 3D intelligent engineering management and control technology for the entire process of the construction of long-span valve hall engineering is proposed, which realizes the entire process simulation and control of engineering construction based on WebGL technology. Accordingly, a three-dimensional intelligent engineering management and control system for the entire construction process of a long-span valve hall project in Southeast China is established, which can effectively manage and apply the data, display and analyze the three-dimensional model, and control and make decisions regarding the construction schedule. This study provides support for the construction of "smart engineering", promotes information communication and transmission between different project units, and speeds up the transformation from traditional construction management relying on drawings to three-dimensional intelligent construction management based on cloud services.

Augmented Reality based Mobile Application for Energy Monitoring and IoT Device Control

IoT has become an integrated part of our lives changing ways in which we operate our everyday appliances. In addition to making our home appliances smart, it has become a common trend for companies to adopt industry 4.0, which uses various sensors to monitor the equipment, machinery, and the work environment. We often come across multiple brands which make smart appliances but each brand comes with its separate mobile application for the appliance's operation. This requires us to switch between Apps to control these appliances if we at all remember which App controls which appliance. We intend to solve these two major inconveniences by creating a single mobile application that can control all these appliances using Augmented Reality technology. All we have to do is point our camera at the appliance that we need to operate and the App will display control options in real-time AR. This paper produces five important contributions: 1) An AR-based mobile application to control IoT devices and monitor the environment. 2) Implementing the mobile application using Unity 3D engine and Vuforia SDK. 3) Integrating a commercially available IoT device with the mobile application. 4) Integrating custom-made hardware IoT device with mobile application. 5) Integrating this combination to make our industries and homes smarter Keywords:

Application of dental stem cells in three-dimensional tissue regeneration.

Dental stem cells can differentiate into different types of cells. Dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, stem cells from apical papilla, and dental follicle progenitor cells are five different types of dental stem cells that have been identified during different stages of tooth development. The availability of dental stem cells from discarded or removed teeth makes them promising candidates for tissue engineering. In recent years, three-dimensional (3D) tissue scaffolds have been used to reconstruct and restore different anatomical defects. With rapid advances in 3D tissue engineering, dental stem cells have been used in the regeneration of 3D engineered tissue. This review presents an overview of different types of dental stem cells used in 3D tissue regeneration, which are currently the most common type of stem cells used to treat human tissue conditions.

Effects of mechanical properties of gelatin methacryloyl hydrogels on encapsulated stem cell spheroids for 3D tissue engineering

Cell spheroids are three-dimensional cell aggregates that have been widely employed in tissue engineering. Spheroid encapsulation has been explored as a method to enhance cell-cell interactions. However, the effect of hydrogel mechanical properties on spheroids, specifically soft hydrogels (<1 kPa), has not yet been studied. In this study, we determined the effect of encapsulation of stem cell spheroids by hydrogels crosslinked with different concentrations of gelatin methacryloyl (GelMA) on the functions of the stem cells. To this end, human adipose-derived stem cell (ADSC) spheroids with a defined size were prepared, and spheroid-laden hydrogels with various concentrations (5, 10, 15%) were fabricated. The apoptotic index of cells from spheroids encapsulated in the 15% hydrogel was high. The migration distance was five-fold higher in cells encapsulated in the 5% hydrogel than the 10% hydrogel. After 14 days of culture, cells from spheroids in the 5% hydrogel were observed to have spread and proliferated. Osteogenic factor and pro-angiogenic factor production in the 15% hydrogel was high. Collectively, our results indicate that the functionality of spheroids can be regulated by the mechanical properties of hydrogel, even under 1 kPa. These results indicate that spheroid-laden hydrogels are suitable for use in 3D tissue construction.

Environmental Impact for 3D Bone Tissue Engineering Scaffolds Life Cycle: An Assessment

With the development of additive manufacturing technology, 3D bone tissue engineering scaffolds have evolved. Bone tissue engineering is one of the techniques for repairing bone abnormalities caused by a variety of circumstances, such as injuries or the need to support damaged sections. Many bits of research have gone towards developing 3D bone tissue engineering scaffolds all across the world. The assessment of the environmental impact, on the other hand, has received less attention. As a result, the focus of this study is on developing a life cycle assessment (LCA) model for 3D bone tissue engineering scaffolds and evaluating potential environmental impacts. One of the methodologies to evaluating a complete environmental impact assessment is life cycle assessment (LCA). The cradle-to-grave method will be used in this study, and GaBi software was used to create the analysis for this study. Previous research on 3D bone tissue engineering fabrication employing poly(ethylene glycol) diacrylate (PEGDA) soaked in dimethyl sulfoxide (DMSO), and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as a photoinitiator will be reviewed. Meanwhile, digital light processing (DLP) 3D printing is employed as the production technique. The GaBi program and the LCA model developed to highlight the potential environmental impact. This study shows how the input and output of LCA of 3D bone tissue engineering scaffolds might contribute to environmental issues such as air, freshwater, saltwater, and industrial soil emissions. The emission contributing to potential environmental impacts comes from life cycle input, electricity and transportation consumption, manufacturing process, and material resources. The results from this research can be used as an indicator for the researcher to take the impact of the development of 3D bone tissue engineering on the environment seriously.

Heat Sterilization Effects on Polymeric, FDM-Optimized Orthopedic Cutting Guide for Surgical Procedures.

Improvements in software for image analysis have enabled advances in both medical and engineering industries, including the use of medical analysis tools to recreate internal parts of the human body accurately. A research analysis found that FDM-sourced elements have shown viability for a customized and reliable approach in the orthopedics field. Three-dimensional printing has allowed enhanced accuracy of preoperative planning, leading to reduced surgery times, fewer unnecessary tissue perforations, and fewer healing complications. Furthermore, using custom tools chosen for each procedure has shown the best results. Bone correction-related surgeries require customized cutting guides for a greater outcome. This study aims to assess the biopolymer-based tools for surgical operations and their ability to sustain a regular heat-sterilization cycle without compromising the geometry and fit characteristics for a proper procedure. To achieve this, a DICOM and FDM methodology is proposed for fast prototyping of the cutting guide by means of 3D engineering. A sterilization test was performed on HTPLA, PLA, and nylon polymers. As a result, the unique characteristics within the regular autoclave sterilization process allowed regular supplied PLA to show there were no significant deformations, whilst annealed HTPLA proved this material’s capability of sustaining repeated heat cycles due to its crystallization properties. Both of these proved that the sterilization procedures do not compromise the reliability of the part, nor the safety of the procedure. Therefore, prototypes made with a similar process as this proposal could be safely used in actual surgery practices, while nylon performed poorly because of its hygroscopic properties.

Effect of low-cost transcranial magnetic stimulation navigation on hotspot targeting and motor evoked potential variability in the biceps brachii.

Transcranial magnetic stimulation (TMS) can monitor or modulate brain excitability. However, reliability of TMS outcomes depends on consistent coil placement during stimulation. Neuronavigated TMS systems can address this issue, but their cost limits their use outside of specialist research environments. The objective was to evaluate the performance of a low-cost navigated TMS approach in improving coil placement consistency and its effect on motor evoked potentials (MEPs) when targeting the biceps brachii at rest and during voluntary contractions. We implemented a navigated TMS system using a low-cost 3D camera system and open-source software environment programmed using the Unity 3D engine. MEPs were collected from the biceps brachii at rest and during voluntary contractions across two sessions in ten non-disabled individuals. Motor hotspots were recorded and targeted via two conditions: navigated and conventional. The low-cost navigated TMS system reduced coil orientation error (pitch: 1.18°±1.2°, yaw: 1.99°±1.9°, roll: 1.18°±2.2° with navigation, versus pitch: 3.7°±5.7°, yaw: 3.11°±3.1°, roll: 3.8°±9.1° with conventional). The improvement in coil orientation had no effect on MEP amplitudes and variability. The low-cost system is a suitable alternative to expensive systems in tracking the motor hotspot between sessions and quantifying the error in coil placement when delivering TMS. Biceps MEP variability reflects physiological variability across a range of voluntary efforts, that can be captured equally well with navigated or conventional approaches of coil locating.

Chick Embryo Experimental Platform for Micrometastases Research in a 3D Tissue Engineering Model: Cancer Biology, Drug Development, and Nanotechnology Applications.

Colonization of distant organs by tumor cells is a critical step of cancer progression. The initial avascular stage of this process (micrometastasis) remains almost inaccessible to study due to the lack of relevant experimental approaches. Herein, we introduce an in vitro/in vivo model of organ-specific micrometastases of triple-negative breast cancer (TNBC) that is fully implemented in a cost-efficient chick embryo (CE) experimental platform. The model was built as three-dimensional (3D) tissue engineering constructs (TECs) combining human MDA-MB-231 cells and decellularized CE organ-specific scaffolds. TNBC cells colonized CE organ-specific scaffolds in 2–3 weeks, forming tissue-like structures. The feasibility of this methodology for basic cancer research, drug development, and nanomedicine was demonstrated on a model of hepatic micrometastasis of TNBC. We revealed that MDA-MB-231 differentially colonize parenchymal and stromal compartments of the liver-specific extracellular matrix (LS-ECM) and become more resistant to the treatment with molecular doxorubicin (Dox) and Dox-loaded mesoporous silica nanoparticles than in monolayer cultures. When grafted on CE chorioallantoic membrane, LS-ECM-based TECs induced angiogenic switch. These findings may have important implications for the diagnosis and treatment of TNBC. The methodology established here is scalable and adaptable for pharmacological testing and cancer biology research of various metastatic and primary tumors.

Advances in Modeling Alzheimer's Disease In Vitro

Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by progressive memory loss and cognitive impairment, thereby disrupting the performance of daily activities. Numerous therapeutics have shown efficacy in animal AD models but failed in human patients. The key to understanding the etiology of AD lies in the development of effective disease models, which can ideally recapitulate all characteristics of the disease. Over the years, different approaches including in vitro, in vivo, and in silico models are able to resemble certain features of AD. In this review, the significance of different in vitro models including their merits and limitations in modeling AD is discussed, which will give a better perspective on the development of a comprehensive model that can mimic human AD. This starts with a brief introduction to AD and its pathology. Then it mainly focuses on the two‐dimensional, three‐dimensional and microfluidic in vitro models of AD that have made significant advancements in understanding AD pathology and aiding in screening effective therapeutics. Several 3D neural tissue engineering models developed in the last two decades along with a discussion on the future prospects in the development of efficient in vitro AD models are further highlighted.

Design and Practice of Virtual Simulation Teaching Experimental Platform for Marine Oil and Gas Exploration

This paper introduces a virtual simulation teaching experimental platform based on Unity 3D engine development. The platform is designed for the purpose of aiming at the frontiers of oceanography, improving teaching efficiency, stimulating interest in learning, and training practice ability. It provides a first-person roaming perspective combined with an operation mode of the human-machine dialogue UI. It is equipped with the function modules of submarine topographic and geomorphological survey, marine seismic exploration, marine geochemical exploration and hydrocarbon accumulation elements. The design of such modules enable students can learn to understand the operation of various instruments and equipment related to marine geological survey and hydrocarbon exploration, and obtain a more realistic human-machine interaction experience in the virtual scene. This platform is dedicated to guiding students to master the geological data collection and analysis methods in the field of offshore oil and gas exploration, to clarify the internal relationship between the formation and evolution of marine sedimentary basins and the enrichment of offshore oil and gas, and to reveal the offshore hydrocarbon exploration process. Therefore, we can make full use of the advantages of virtual simulation, which will help to improve the teaching effect and have a distinct practical role in the teaching of oceanography experiments.

The vascular clock: a new insight into endothelial cells and pericytes crosstalk

Abstract Background/Introduction Circadian rhythms, defined as biological oscillations with a period of circa 24h, regulate many physiological processes in the cardiovascular system, such as vascular function, vascular tone, blood pressure, heart rate and thrombus formation [1]. The vasculature responds to the main pacemaker located in the brain, but it also possesses its own clock. Indeed, a molecular clock has been identified in endothelial cells (EC) and smooth muscle cells (SMC). The disruption of the circadian clock profoundly affects cardiovascular functionality with adverse cardiovascular events such as myocardial infarction or stroke showing a 24h rhythmicity with a peak incidence in the early morning. Among several mechanisms affected by circadian dysregulation, angiogenesis plays a fundamental role in homeostasis and development of new blood vessels. EC and pericytes (PC) are the two main cell populations in the capillaries, and their physical and paracrine interaction drives and regulates the sprouting. However, the presence and the role of circadian rhythms in pericytes and whether the molecular clock affects the endothelial/pericyte interactions remain unexplored. Purpose The aim of this study is to identify a molecular clock in human vascular pericytes and elucidate the impact of the circadian clock on the formation of new blood vessels. Methods Human primary PC were synchronised and the rhythmicity of clock genes measured by luminescence, immunofluorescence, and qPCR. Synchronised PC were co-cultured with Bmal1::LUC human primary EC. The effect of PC synchronisation and circadian clock disruption by shRNA on EC clock genes and angiogenic potential were measured by luminescence and Matrigel assay, respectively. A macroporous polyurethane scaffold was developed for 3D co-cultures. Results PC presented rhythmic expression of the principal circadian genes with a circa 24h period but in our experimental setting, EC did not show circadian rhythmicity. Synchronised PC supported the rhythmic expression of the clock gene Bmal1 in EC in a contact co-culture system, suggesting a secondary form of EC molecular clock regulation. Non-contact co-cultures failed to synchronise EC. Furthermore, when the clock was disrupted in PC, their capacity to support EC's tube-forming capacity on Matrigel was impaired; clock disruption in EC did not affect angiogenesis, supporting the hypothesis that a disrupted clock in perivascular cells affects angiogenesis. In a 3D tissue engineering scaffold seeded with both EC and PC, the synchronisation of the clock led to the development of organised vascular-like structures around the scaffold's pores, as compared to the non-synchronised condition where cells appeared disorganised. Conclusion This study defines for the first time the existence of an endogenous molecular circadian clock in perivascular cells and suggests implications for circadian clock synchronisation in physiological and therapeutic angiogenesis. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): University of Surrey Doctoral CollegeUniversity of Surrey Bioprocess and Biochemical Engineering (BioProChem) Group.

Integrating 3D Game Engines in Enhancing Urban Perception: A Case Study of Students' Visualization of Urban Space

En el disseny urbà, la consideració de la participació, la percepció i l'experiència urbanes és molt important per aconseguir un disseny espacial exitós, fàcil d'implementar i amigable per a l'usuari. La visualització urbana participativa és un mètode que permet als residents involucrar-se en la formulació del futur de la localitat. Aquest document informa un estudi de cas de participació de 15 estudiants voluntaris en la visualització del futur de la seva localitat a través de tres mètodes: models físics, recorregut animat prerenderitzat i una demostració interactiva en temps real. L'estudi examina l'impacte de l'ús del motor de joc (3D) Unity, de tres dimensions, a la capacitat d'imatge i comprensió de l'espai urbà. En conseqüència, aquest article presenta un estudi comparatiu de les tres tècniques de visualització mitjançant l'anàlisi dels resultats d'una sèrie d'experiments, un qüestionari i observacions. Els resultats donen suport que el motor de joc 3D (Unity) utilitzat proporciona una eina eficient que pot ajudar els usuaris a experimentar, percebre i comprendre les solucions urbanes de manera interactiva i eficaç. A més, aquest estudi confirma el paper de la tecnologia en la millora de lexperiència daprenentatge de lusuari. A més, els resultats de lestudi indiquen que la integració de la tecnologia de jocs interactius en la visualització de lespai urbà té un efecte positiu en la percepció espacial de les persones. In urban design, consideration of urban participation, perception, and experience is very important for achievement of successful, easy-to-implement, and user-friendly spatial design. Participatory urban visualization is a method that allows residents to be involved in formulating the future of their locality. This paper reports a case study of participation of 15 volunteer students in visualization of the future of their locality via three methods: physical models, pre-rendered animated walkthrough, and an interactive real-time demo. The study examines the impact of using the three-dimension (3D) Unity game engine on urban space imageability and understanding. Accordingly, this paper presents a comparative study of the three visualization techniques by analyzing the results of a series of experiments, a questionnaire, and observations. The outcomes support that the used 3D game engine provides an efficient tool that can help users to experience, perceive, and understand urban solutions interactively and effectively. Furthermore, this study confirms the role of technology in enhancing the user’s learning experience. Additionally, the study results indicate that integrating interactive game technology in urban space visualization has positive effect on space perception of people. En el diseño urbano, la consideración de la participación, percepción y experiencia urbanas es muy importante para lograr un diseño espacial exitoso, fácil de implementar y amigable para el usuario. La visualización urbana participativa es un método que permite a los residentes involucrarse en la formulación del futuro de su localidad. Este documento informa un estudio de caso de participación de 15 estudiantes voluntarios en la visualización del futuro de su localidad a través de tres métodos: modelos físicos, recorrido animado pre-renderizado y una demostración interactiva en tiempo real. El estudio examina el impacto del uso del motor de juego Unity de tres dimensiones (3D) en la capacidad de imagen y comprensión del espacio urbano. En consecuencia, este artículo presenta un estudio comparativo de las tres técnicas de visualización mediante el análisis de los resultados de una serie de experimentos, un cuestionario y observaciones. Los resultados respaldan que el motor de juego 3D (Unity) utilizado proporciona una herramienta eficiente que puede ayudar a los usuarios a experimentar, percibir y comprender las soluciones urbanas de manera interactiva y eficaz. Además, este estudio confirma el papel de la tecnología en la mejora de la experiencia de aprendizaje del usuario. Además, los resultados del estudio indican que la integración de la tecnología de juegos interactivos en la visualización del espacio urbano tiene un efecto positivo en la percepción espacial de las personas.

When Pigs Fly: Contextual Reasoning in Synthetic and Natural Scenes.

Context is of fundamental importance to both human and machine vision; e.g., an object in the air is more likely to be an airplane than a pig. The rich notion of context incorporates several aspects including physics rules, statistical co-occurrences, and relative object sizes, among others. While previous work has focused on crowd-sourced out-of-context photographs from the web to study scene context, controlling the nature and extent of contextual violations has been a daunting task. Here we introduce a diverse, synthetic Out-of-Context Dataset (OCD) with fine-grained control over scene context. By leveraging a 3D simulation engine, we systematically control the gravity, object co-occurrences and relative sizes across 36 object categories in a virtual household environment. We conducted a series of experiments to gain insights into the impact of contextual cues on both human and machine vision using OCD. We conducted psychophysics experiments to establish a human benchmark for out-of-context recognition, and then compared it with state-of-the-art computer vision models to quantify the gap between the two. We propose a context-aware recognition transformer model, fusing object and contextual information via multi-head attention. Our model captures useful information for contextual reasoning, enabling human-level performance and better robustness in out-of-context conditions compared to baseline models across OCD and other out-of-context datasets. All source code and data are publicly available at https://github.com/kreimanlab/WhenPigsFlyContext.

Nonlinear IGABEM formulations for the mechanical modelling of 3D reinforced structures

The adequate coupling of dissimilar materials and structural element types provides effective engineering designs. Particularly, it enables high stiffness and low weight mechanical components, which are largely desired in numerous applications. Besides, Isogeometric Analysis (IGA) has recently stood out as a robust and accurate approach for the mechanical modelling of complex 3D engineering designs directly from Computer-Aided Design (CAD) tools. In this context, this study presents nonlinear Isogeometric Boundary Element Method (IGABEM) formulations for the effective mechanical modelling of nonhomogeneous 3D structural systems reinforced by embedded fibres. The IGABEM based on NURBS surfaces represents the solid whereas the 1D approach of BEM models the reinforcements, which characterises a 1DBEM/IGABEM coupling technique. The sub-region technique enables the nonhomogeneous system modelling whereas connection 1DBEM elements allow for crossing reinforcements along boundary interfaces without the need for surfaces remeshing. Thus, the CAD model information can be straightforwardly used in the mechanical model. Nonlinear time independent formulations are presented accounting for both elastoplastic and bond-slip behaviours. Besides, linear and nonlinear time dependent formulations are presented herein applying the Kelvin-Voigt and Boltzmann viscoelastic rheological models. Five applications illustrate the accuracy and robustness of the proposed formulations. The IGABEM formulations lead to accurate and stable results, in addition to efficient modelling. Besides, it demonstrates excellent performance considering the computational time consuming and the total number of degrees of freedom in each application.

Applying Constraint Weighting to Autonomous Camera Control

Automating camera control for third-person perspective computer games is a difficult and time-consuming task. One of the challenges games developers confront is how to manage the trade-off between implementation complexity and system usability. In this study, we investigate the application of constraint weighting techniques to the autonomous camera control problem. We demonstrate that this technique can significantly simplify autonomous camera control and reduce the gap between implementation and usability requirements. We describe the use of weighting profiles to control the behaviour of the camera and specialized heuristics for efficiently searching for the solution. We also describe a novel integrated visibility maintenance method. As part of the experimental study, we implemented a 3D game engine that supports dynamic environments; and demonstrate the effectiveness of the use of constraint solving techniques for autonomous camera control problems.

Alginate-based self-healing hydrogels assembled by dual cross-linking strategy: Fabrication and evaluation of mechanical properties

One way to enhance the poor mechanical properties of the self-healing hydrogels based on host-guest (HG) interaction is employing the dual cross-linking method. Here, the alginate-based hydrogels based on HG complexation were prepared through the modification of alginate (ALG) polysaccharide with beta-cyclodextrin (βCD) and adamantane (Ad) as host and guest groups with different grafting values, respectively. The porous structure was confirmed for all ALG-CD:ALG-Ad hydrogels. The average pore size of ALG-CD1:ALG-Ad1 hydrogel cross-linked by HG interactions was 288 μm. Mechanical properties of the alginate-based HG hydrogels were improved by incorporating Ca2+ ions in their structure through dual cross-linking methodology. The maximum modulus of the porous dual-crosslinked hydrogel was reached up to 6500 Pa. The healing time of less than 5 s was obtained for the alginate-based hydrogels. The fabricated hydrogels can be used in 3D printing, tissue engineering, and drug delivery systems due to their biocompatibility and shear-thinning behavior.

Hydrogen Bonding Stiffens Peptide Amphiphile Supramolecular Filaments by Aza-Glycine Residues

Peptide amphiphiles (PAs) are a class of molecules comprised of short amino acid sequences conjugated to hydrophobic moieties that may exhibit self-assembly in water into supramolecular structures. We investigate here how mechanical properties of hydrogels formed by PA supramolecular nanofibers are affected by hydrogen bond densities within their internal structure by substituting glycine for aza-glycine (azaG) residues. We found that increasing the number of PA molecules that contain azaG up to 5 mol% in PA supramolecular nanofibers increases their persistence length fivefold and decreases their diffusion coefficients as measured by fluorescence recovery after photobleaching. When these PAs are used to create hydrogels, their bulk storage modulus (G′) was found to increase as azaG PA content in the supramolecular assemblies increases up to a value of 10 mol% and beyond this value a decrease was observed, likely due to diminished levels of nanofiber entanglement in the hydrogels as a direct result of increased supramolecular rigidity. Interestingly, we found that the bioactivity of the scaffolds toward dopaminergic neurons derived from induced pluripotent stem cells can be enhanced directly by persistence length independently of storage modulus. We hypothesize that this is due to interactions between the cells and the extracellular environment across different size scales: from filopodia adhering to individual nanofiber bundles to cell adhesion sites that interact with the hydrogel as a bulk substrate. Fine tuning of hydrogen bond density in self-assembling peptide biomaterials such as PAs provides an approach to control nanoscale stiffness as part of an overall strategy to optimize bioactivity in these supramolecular systems. supramolecular biomaterials. Statement of significanceHydrogen bonding is an important driving force for the self-assembly of peptides in both biological and artificial systems. Here, we increase the amount of hydrogen bonding within self-assembled peptide amphiphile (PA) nanofibers by substituting glycine for an aza-glycine (azaG). We show that increasing the molar concentration of azaG increases the internal order of individual nanofibers and increases their persistence length. We also show that these changes are sufficient to increase survival and tyrosine hydroxylase expression in induced pluripotent stem cell-derived dopaminergic neurons cultured in 3D gels made of these materials. Our strategy of tuning the number of hydrogen bonds in a supramolecular assembly provides mechanical customization for 3D cell culture and tissue engineering.

Electrospun natural rubber latex biocomposite for scaffolds in tissue engineering

Fibrous scaffold along with seed cells are essential players for engineered tissue regeneration. Recently, PLGA/epoxidized poly(isoprene) dense membranes have been evaluated for cell growth and have shown satisfactory results. However, porous and fibrous structures suitable for obtaining 3D supports have not yet been evaluated for the PLGA/epoxidized poly(isoprene). The present work aimed to establish the electrospinning conditions for obtaining electrospun membranes with a smaller diameter of fibers and adequate morphology, which were characterized in vitro by their physical, chemical and biological properties. The best electrospun fibers were obtained from the following conditions: an applied voltage of 15 kV, a needle-collector distance of 20 cm and, a flow rate of 5 mL/h. The functional groups of the polymers involved in the blend did not show any changes. The mechanical properties of the electrospun membranes are within the lower limits known to human skin and some soft tissues. The in vitro degradation test showed a loss of mass of approximately 20% in 28 days. Significant adhesion and proliferation of human adipose–derived mesenchymal stem cells were demonstrated, indicating that there was cellular penetration into the scaffold and proliferation. Therefore, the preliminary results suggest that the electrospun PLGA/epoxidized poly(isoprene) membranes have high potential for application as a 3D tissue engineering scaffold.