Complex 3D Structure Research Articles

Comparative effect of ionic liquids pretreatment on thermogravimetric kinetics of crude oil palm biomass for possible sustainable exploitation

Crude oil palm biomass (OPB) residue is an important source of lignocellulose and could be transformed into biofuels through thermochemical conversion for heat and power in CHP plants or act as sustainable reinforcement in the biocomposite industry. Effective pretreatment is an essential task for the utilization of waste biomass for bioenergy and biomaterials. The comparative effect of two ionic liquids (ILs), 1-butyl-3-methylimidazolium chloride ([bmim][Cl]) and 1-ethyl-3-methylimidazolium diethylphosphate ([emim[dep]), on OPB pyrolysis kinetic and thermodynamic parameters was studied using thermogravimetric analysis (TGA) coupled with Coats-Redfern integral method. The OPB residue was pretreated with ILs [bmim][Cl] and [emim][dep] under mild processing conditions of 90 °C for 3 h and was also subjected to three other conventional pretreatment methods called dilute acid, alkaline, and hot compressed water to better understand and compare the performance of ILs for pretreatment of lignocellulosic OPB. Results reveal that ILs pretreatment was superior in terms of delignification of OPB and produced the cellulose-rich fiber with 48.2% and 41.2% cellulose compared to cellulose fraction of 26.4% for the untreated sample. The values of apparent activation energies were found to be 81.8, 90.9, 92.0, 84.9, 83.8, and 93.5 kJ/mol for untreated, [bmim][Cl], [emim][dep], dilute acid, base, and hot compressed water pretreatments respectively. Further calculation of thermodynamic parameters led to the change in Gibb's free energy (ΔG°) values of 188.9, 208.0, 210.9, 219.1, 217.4 and 217.1, kJ/mol for untreated, [bmim][Cl], [emim][dep], dilute acid, base, and hot compressed water pretreatments respectively. The higher change in entropy (ΔS°) values of ILs-pretreated fibers compared to the untreated one showed that dissolution and regeneration from ILs solution had unlocked the complex 3D structure of lignocellulose, resulting in increased disorder. The results plainly revealed that ILs-based pretreatment could be a promising and environmentally benign technology for efficient utilization of agricultural residues in the fields of biofuels and biocomposite materials.

Three Organic/Inorganic Nanolayers on Flexible Foam Allow Retaining Superior Flame Retardancy Performance Upon Mechanical Compression Cycles

The water-based deposition of flame retardant coatings on flexible polyurethane foams has attracted great interest among scientific community due to the great performances associated with this technology. Unfortunately, this approach results inefficient as it requires a high number of steps in order to achieve the desired properties. In this paper, we report the production of flame retardant foams by means of the simple deposition of only three nanoparticles containing layers. The composition and order of the deposited layer has been designed in order to provide specific flame retardant actions, targeting delayed release of polymer decomposition products to the gas phase, dilution of these flammable products with water and intumescent barrier formation. The morphology of the coated foams after the adsorption of each layer has been investigated by scanning electron microscopy, demonstrating the ability of each adsorbed layer to completely wrap the complex 3D structure of the foam. This three layers based coating produces a protective exoskeleton that is capable of self-extinguishing the flame in standard flammability tests, leaving the foam almost unaffected (final residue 98%). In forced combustion tests by cone calorimetry, treated foams showed considerably reduced combustion rates, with reduced peak of heat release rate (-50%) as well as consistent reduction in the smoke optical density (-51%) and the total smoke release (-34%). In addition, treated foams have been demonstrated to maintain the ability to self-extinguish the flame as well as reduced combustion rates and smoke production even after being subjected to 100 compression cycles.

Anatomy of Skyrmionic Textures in Magnetic Multilayers.

Room temperature magnetic skyrmions in magnetic multilayers are considered as information carriers for future spintronic applications. Currently, a detailed understanding of the skyrmion stabilization mechanisms is still lacking in these systems. To gain more insight, it is first and foremost essential to determine the full real-space spin configuration. Here, two advanced X-ray techniques are applied, based on magnetic circular dichroism, to investigate the spin textures of skyrmions in [Ta/CoFeB/MgO]n multilayers. First, by using ptychography, a high-resolution diffraction imaging technique, the 2D out-of-plane spin profile of skyrmions with a spatial resolution of 10 nm is determined. Second, by performing circular dichroism in resonant elastic X-ray scattering, it is demonstrated that the chirality of the magnetic structure undergoes a depth-dependent evolution. This suggests that the skyrmion structure is a complex 3D structure rather than an identical planar texture throughout the layer stack. The analyses of the spin textures confirm the theoretical predictions that the dipole-dipole interactions together with the external magnetic field play an important role in stabilizing sub-100 nm diameter skyrmions and the hybrid structure of the skyrmion domain wall. This combined X-ray-based approach opens the door for in-depth studies of magnetic skyrmion systems, which allows for precise engineering of optimized skyrmion heterostructures.

Building an Artificial Stem Cell Niche: Prerequisites for Future 3D-Formation of Inner Ear Structures-Toward 3D Inner Ear Biotechnology.

ABSTRACTIn recent years, there has been an increased interest in stem cells for the purpose of regenerative medicine to deliver a wide range of therapies to treat many diseases. However, two‐dimensional cultures of stem cells are of limited use when studying the mechanism of pathogenesis of diseases and the feasibility of a treatment. Therefore, research is focusing on the strengths of stem cells in the three‐dimensional (3D) structures mimicking organs, that is, organoids, or organ‐on‐chip, for modeling human biology and disease. As 3D technology advances, it is necessary to know which signals stem cells need to multiply and differentiate into complex structures. This holds especially true for the complex 3D structure of the inner ear. Recent work suggests that although other factors play a role, the extracellular matrix (ECM), including its topography, is crucial to mimic a stem cell niche in vitro and to drive stem cells toward the formation of the tissue of interest. Technological developments have led to the investigation of biomaterials that closely resemble the native ECM. In the fast forward moving research of organoids and organs‐on‐chip, the inner ear has hardly received attention. This review aims to provide an overview, by describing the general context in which cells, matrix and morphogens cooperate in order to build a tissue, to facilitate research in 3D inner ear technology. Anat Rec, 303:408–426, 2020. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Rapid high-quality 3D micro-machining by optimised efficient ultrashort laser ablation

Solid-state lasers with pulse duration of 10 ps and radiation wavelength of 1064 nm were used to investigate the laser ablation efficiency dependence on processing parameters: laser fluence (pulse energy and beam spot size), beam scanning speed, pulse repetition rate, and scanned line (hatch) distance for the copper sample. Utilising a 40 W power laser, the highest ablation efficiency of 2.5 µm3/µJ and the ablation rate of 100 µm3/µs with the smallest surface roughness of 0.2 µm was obtained. Three-dimensional (3D) fabrication using a galvanometer scanner and layer-by-layer removal technique with optimal parameters defined for efficient ablation were demonstrated at a rate of 6 mm3/min. Combination of high material removal rate with excellent quality and complex 3D structure formation is in a high interest for mimicking bio-inspired surfaces, micro-mould fabrication and decorative applications.

A novel morphometry system automatically assessing the growth and regeneration of intestinal organoids

As compared with 2D cell line cultures, 3D intestinal organoids are better at maximally recapitulating the physiological features of stem cells in vivo. However, the complex 3D structure is an obstacle which must be objectively and automatically evaluated to assess colony growth and regeneration. Meanwhile, no internal standard currently exists for evaluating the size of heterogeneities in organoids or defining those regenerating colonies. Herein, we developed a simple morphometry system to image MTT-stained organoids. The growth curve of organoids can be automatically generated based upon analyzing the integrated optical density using software. Referencing the definition standards of in vivo regenerating crypts, the perimeters of crypts cultured 24 h after seeding were selected as an “Organoid Unit” to further evaluate colony survival rate and colony size heterogeneities after exposure to varying doses of irradiation. Moreover, the morphometry-based quantification data collected confirmed other findings associated with radiation sensitizing effects of ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related protein (ATR) inhibitor and the radiation protective effect of IL-22. In summary, the novel organoid morphometry system combined with a new internal reference is a practical means for standardizing assessment of growth, survival and regeneration of intestinal organoid colonies. This method has promise to facilitate drug screens in intestinal and other organoid systems.

Synchrotron X-ray tomography investigation of 3D morphologies of intermetallic phases and pores and their effect on the mechanical properties of cast Al-Cu alloys

The influence of Fe content on the three-dimensional (3D) morphologies of Fe-rich intermetallic phases (Fe phases), Al2Cu, and pores and mechanical properties of cast Al-5.0Cu-0.6Mn alloys with 0.5 and 1.0 wt % Fe are characterized using synchrotron X-ray tomography and a tensile test. The results show that both Fe phases and Al2Cu exhibit a complex 3D network structure, and the pores are irregular with complex interconnected and near-globular shape. As the Fe content increases from 0.5% to 1.0%, the volume fraction and equivalent diameter of Fe phases increase, whereas both their interconnectivities decrease. Skeletonization analysis shows that the Chinese-script-shaped Fe phase is more compacted than the plate-like Fe phases. The equivalent diameter and sphericity of pores vary with Fe content, and their relationships follow exponential functions. The addition of Fe results in a decrease in the ultimate tensile strength and elongation from 224 MPa to 200 MPa and from 5.5% to 3.6%, respectively, owing to increasing volume fraction of sharp-edged Fe phases and pores, resulting in stress concentration during tensile test.

Numerical simulation of SIF in Es-Salam research reactor vessel

Abstract During NPP operation the reactor vessel will be affected by degradation mechanizms, such as thermal aging, irradiation embrittlement, corrosion and fatigue. These degradation mechanisms may significantly impact component integrity. When the metal is aging under certain conditions, the crack can appear and this finally could lead to the failure of components. The stress intensity factor (SIF) as fracture criterion are used to evaluate the resistance to fracture of the components with cracks. In the case of complex structures the estimation of stress intensity factor it is complicated by applying only the analytical formulas. The Es-Salam research reactor vessel is a complex 3D structure with high level safety requirements. As a result, sophisticated methods are necessary for the fracture analysis of critical components. In this manuscript the proposed methodology for the numerical simulation of the stress intensity factor in Es-Salam research reactor vessel by finite element method using software ANSYS is presented. The validation of the proposed methodology was performed by analytical analysis (according ASME requirement and R6 method (SACC software)). Additionally this methodology was validated by applying a finite element method using software ABAQUS. The comparison of these results shows a good coincidence, and the deviation does not exceed 9%. According to this, the proposed methodology can be used for numerical simulation of the stress intensity factor in Es-Salam research reactor vessel.

Molecular-level driving forces in lignocellulosic biomass deconstruction for bioenergy

The plant cell wall biopolymers lignin, cellulose and hemicellulose are potential renewable sources of clean biofuels and high-value chemicals. However, the complex 3D structure of lignocellulosic biomass is recalcitrant to deconstruction. Major efforts to overcome this recalcitrance have involved pretreating biomass before catalytic processing. This Perspective describes recent work aimed at elucidating the molecular-level physical phenomena that drive biomass assembly. These are at play in commonly employed aqueous-based and thermochemical pretreatments. Several key processes have been found to be driven by biomass solvation thermodynamics, an understanding of which therefore facilitates the rational improvement of methods aimed at the complete solubilization and fractionation of the major biomass components. This Perspective describes the physical molecular driving forces that stabilize native lignocellulosic plant biomass structures and govern thermochemical biomass pretreatments. Understanding these driving forces can help us to design efficient methods for deconstructing biomass into biofuels and other bioproducts.

Therapeutic Applications of Phytoplankton, with an Emphasis on Diatoms and Coccolithophores

AbstractPhytoplankton are complex living organisms that have attracted significant interest in the field of biomedicine. One subclass of phytoplankton, the diatoms, produce elegant self‐assembled siliceous architectural features with a complex 3D porous structure. Diatoms are characterized by a distinct 3D architecture of silica cell walls called frustules with a highly ordered nano‐/micropore structure and pattern. Another phytoplankton subclass of interest is the coccolithophore, which produces unique calcium carbonate plates with distinct architectural features called coccoliths. The unique morphological characteristics of coccoliths resembling the shape of a wagon wheel allows a higher surface area, thus an increased amount of immobilized therapeutic agent on their surface compared to a synthetic calcium carbonate microparticle. This review offers a summary of phytoplankton (microalgae) and their potential for application in drug delivery, diagnostics, drug discovery, as molecular factories, and as scaffolds for various therapeutic applications.

Layer-by-layer-assembled chitosan/phosphorylated cellulose nanofibrils as a bio-based and flame protecting nano-exoskeleton on PU foams

The layer-by-layer (LbL) assembly of chitosan (CH) and phosphorylated cellulose nanofibrils (P-CNF) is presented as a novel, sustainable and efficient fire protection system for polyurethane foams. The assembly yields a linearly growing coating where P-CNF is the main component and is embedded in a continuous CH matrix. This CH/P-CNF system homogenously coats the complex 3D structure of the foam producing a nano-exoskeleton that displays excellent mechanical properties increasing the modulus of the foam while maintaining its ability of being cyclically deformed. During combustion the CH/P-CNF exoskeleton efficiently prevents foam collapse and suppresses melt dripping while reducing the heat release rate peak by 31% with only 8% of added weight. The coating behavior during combustion is investigated and correlated to the observed performances. Physical and chemical mechanisms are identified and related to the unique composition and structure of the coating imparted by the LbL assembly.

Chemoresistance of cancer floating cells is independent of their ability to form 3D structures: Implications for anticancer drug screening.

Three-dimensional (3D) culture systems such as floating spheroids (FSs) and floating tumorspheres (FTs) are widely used as tumor models of chemoresistance. FTs are considered to be enriched in cancer stem-like cells (CS-LCs). In this study, we used cancer cell lines (lung H460, prostate LnCAP, and breast MCF-7) able to form FSs under anchorage-independent conditions and compared with cell lines (prostate PC3 and breast MDA-MB-231) that cannot form FSs under similar conditions. Independent of their ability to form FTs all cell lines growing under anchorage-independent conditions become highly resistant to obatoclax, colchicine, and hydroxyurea. We used anti-E-cadherin antibody (that blocked the formation of FSs) and demonstrated that floating LnCAP cells showed similar chemoresistance regardless of the formation of spheroids. Our results demonstrate that the development of chemoresistance is not because of the formation of a complex 3D structure and/or enrichment of CS-LCs but is likely the result of cell detachment per se and their ability to survive under anchorage-independent conditions. We propose that FSs and FTs could be useful models to study chemoresistance of cancer cells associated with cell detachment (e.g., circulating tumor cells) but they may not be representative of other types of chemoresistance that arise in vivo in attached cells.

Abstract: Inferring 3D Craniofacial Skeletal Shape from Facial Surface Geometry Using Reverse Engineering of a Forensic Tissue Depth Model

PURPOSE: The face and craniofacial skeleton (CFS) make up a complex 3D structure that is critical to human function and cosmesis. Traumatic injury to the CFS requires fracture treatment to both allow the recovery of mechanical function and forms a foundation for the restoration of soft tissue anatomy. CFS reconstruction aims to restore pre-injury appearance, however in severe injuries shape information for the skull and facial bones may be missing. This presents a particular challenge in bi-frontal injuries and pan-facial fractures where the mirror imaging of the intact side of the head cannot be used to guide reconstruction. The reconstruction of 3D facial surface geometry from pre-injury 2D photographs has recently been established through large scale morphable face modeling.1 As well, in forensic sciences, models with variable soft-tissue depths2 are used to determine face shape from skull geometry. This study aims to ‘reverse-engineer’ a forensics’ tissue depth model to determine pre-injury CFS shape from reconstructed 3D facial geometry. It is hypothesized that 3D forensics data can be used to fill in missing gaps in CFS geometry with sufficient accuracy to guide pre-operative planning for CFS reconstruction. METHODS: The forensics’ tissue depth model was applied to 3D facial geometries acquired through segmentation of head CT data. Age, sex and BMI were used as input parameters to guide the application of the forensics’ tissue depth model data to each face. The tissue depths between the face and CFS were determined by finding the Euclidian distance transform (nearest neighbor) employed by the original forensics study and via calculation using normal vectors generated from the face surface. Calculated tissue depth was evaluated against measured thickness on the head CT between the segmented CFS (bone) and the skin. RESULTS: Tissue depth determined by nearest neighbor and normal vector measurements yielded accurate reconstructions of the frontal and zygoma bones (within 1mm, or +/- 2 voxels). However, only the normal vector technique succeeded in estimating tissue depth in bone regions where the face and skull have differing concavity (i.e. eye sockets, maxilla). Agreement was more limited in the lower facial skeleton where greater variation of soft tissue structures occur. CONCLUSION: The reversed forensics tissue depth model was found to appropriately infer bony anatomy for the upper CFS from 3D face geometry. The 3D skull shaping provided by this work yields sufficient accuracy to warrant its inclusion into a translational pipeline of tools for pre-operative planning for CFS reconstruction.

Optical tissue clearing in combination with perfusion and immunofluorescence for placental vascular imaging.

Imaging of placental tissues is a difficult task, because of specific for this organ complex multicellular and 3D tissue structure. The tissue clearing systems (X-CLARITY) system is a valuable tool for the examining the expression of molecular pathways in whole tissues and organs, originally developed for brain imaging.In the present report, we utilized this technology for the examination of placental vasculature and protein expression in perfused human placental tissue.The placental tissue was sufficiently cleared with preservation of endothelial staining and fluorescent markers, allowing visualization using confocal microscopy. The CLARITY method and X-CLARITY system is a valuable tool in placental imaging.

Move the Object or Move Myself? Walking vs. Manipulation for the Examination of 3D Scientific Data

Physical walking is consistently considered a natural and intuitive way to acquire viewpoints in a virtual environment. However, research findings also show that walking requires cognitive resources. To understand how this tradeoff affects the interaction design for virtual environments; we evaluated the performance of 32 participants, ranging from 18 to 44 years old, in a demanding visual and spatial task. Participants wearing a virtual reality (VR) headset counted features in a complex 3D structure while walking or while using a 3D interaction technique for manipulation. Our results indicate that the relative performance of the interfaces depends on the spatial ability and game experience of the participants. Participants with previous game experience but low spatial ability performed better using the manipulation technique. However, walking enabled higher performance for participants with high spatial ability or without significant game experience. These findings suggest that the optimal design choices for demanding visual tasks in VR should consider both controller experience and the spatial ability of the target users.

Digital light processing of wollastonite-diopside glass-ceramic complex structures

In this work, the possibility of shaping a glass-filled photosensitive polymer resin with Digital Light Processing (DLP) into a complex 3D structure and transforming it subsequently into a bioactive glass-ceramic scaffold was investigated. The influence of the printing conditions and the heat-treatment was studied using a 41 vol% glass-filled acrylated polymer resin. Scaffolds with designed architecture were turned into a wollastonite-diopside glass-ceramic at 1100 °C. They completely maintained their shape, exhibited no viscous flow and showed a homogenous linear shrinkage of around 25%. At 83 vol% porosity structures with Kelvin cell design exhibited a compressive strength exceeding 3 MPa, demonstrating that the material is suitable for the fabrication of bioceramic scaffolds for bone tissue engineering applications.

Strain sensing characteristics of 3D‐printed conductive plastics

Three types of commercially available conductive three-dimensional (3D) printing filament are electrically characterised for use in 3D-printed functional devices. The three plastics were carbon dispersed acrylonitrile butadiene styrene, carbon dispersed polylactic acid (PLA) and graphene dispersed PLA. The method of 3D printing used was material extrusion and prints were made in both single and dual extrusion modes. The plastics were found to be piezoresistive, enabling them to be characterised as strain sensors. The electrical characteristics of these materials enabled the measurement of strain using low cost, readily available prototyping equipment and minimising the requirement for dedicated instrumentation components (e.g. Wheatstone bridges). Increasing the thickness of the plastics improved conductivity. However, this also decreased the reliability and reproducibility of strain sensor data due to a complex internal 3D structure. The recommendation for reliable use in prototyping and manufacturing is to print tracking under 0.8 mm thickness, thus producing resistance measurements that are predictable and follow a linear regression up to R2 = 0.9991. A dual extruded 3D print was fabricated as a final demonstration. A force sensing resistor interface was created. The final demonstration uses a PIC18F45K20 microcontroller to process sensor inputs, outputting to an alphanumeric LCD.

Bioprinting Perfusion-Enabled Liver Equivalents for Advanced Organ-on-a-Chip Applications.

Many tissue models have been developed to mimic liver-specific functions for metabolic and toxin conversion in in vitro assays. Most models represent a 2D environment rather than a complex 3D structure similar to native tissue. To overcome this issue, spheroid cultures have become the gold standard in tissue engineering. Unfortunately, spheroids are limited in size due to diffusion barriers in their dense structures, limiting nutrient and oxygen supply. Recent developments in bioprinting techniques have enabled us to engineer complex 3D structures with perfusion-enabled channel systems to ensure nutritional supply within larger, densely-populated tissue models. In this study, we present a proof-of-concept for the feasibility of bioprinting a liver organoid by combining HepaRG and human stellate cells in a stereolithographic printing approach, and show basic characterization under static cultivation conditions. Using standard tissue engineering analytics, such as immunohistology and qPCR, we found higher albumin and cytochrome P450 3A4 (CYP3A4) expression in bioprinted liver tissues compared to monolayer controls over a two-week cultivation period. In addition, the expression of tight junctions, liver-specific bile transporter multidrug resistance-associated protein 2 (MRP2), and overall metabolism (glucose, lactate, lactate dehydrogenase (LDH)) were found to be stable. Furthermore, we provide evidence for the perfusability of the organoids’ intrinsic channel system. These results motivate new approaches and further development in liver tissue engineering for advanced organ-on-a-chip applications and pharmaceutical developments.

Layer-by-layer assembly of efficient flame retardant coatings based on high aspect ratio graphene oxide and chitosan capable of preventing ignition of PU foam

The layer-by-layer (LbL) technique is adopted for the construction of multilayers encompassing chitosan and graphene oxide (GO) platelets capable of improving the flame retardant properties open cell PU foams. The LbL assembly follows a linear growth regime as evaluated by infrared spectroscopy and yields a multilayer structure where GO platelets are embedded within a chitosan continuous matrix. 3 and 6 bi-layers (BL) can efficiently coat the complex 3D structure of the foam and substantially improve its flame retardant properties. 3BL only add 10% to the original mass and can suppress the melt dripping during flammability and reduce both the peak of heat release rate by 54% and the total smoke released by 59% in forced combustion tests. Unprecedented among other LbL assemblies employed for FR purposes, the deposition 6BL is capable of slowing down the release of combustible volatile to the limits of non-ignitability thus preventing ignition in half of the specimens during cone calorimetry tests. This has been ascribed to the formation of a protective coating where the thermally stable char produced by chitosan serves as a continuous matrix embedding GO platelets, which control volatile release while mechanically sustaining the PU foam structure.

Current Concepts in Meniscus Tissue Engineering and Repair.

The meniscus is the most commonly injured structure in the human knee. Meniscus deficiency has been shown to lead to advanced osteoarthritis (OA) due to abnormal mechanical forces, and replacement strategies for this structure have lagged behind other tissue engineering endeavors. The challenges include the complex 3D structure with individualized size parameters, the significant compressive, tensile and shear loads encountered, and the poor blood supply. In this progress report, a review of the current clinical treatments for different types of meniscal injury is provided. The state-of-the-art research in cellular therapies and novel cell sources for these therapies is discussed. The clinically available cell-free biomaterial implants and the current progress on cell-free biomaterial implants are reviewed. Cell-based tissue engineering strategies for the repair and replacement of meniscus are presented, and the current challenges are identified. Tissue-engineered meniscal biocomposite implants may provide an alternative solution for the treatment of meniscal injury to prevent OA in the long run, because of the limitations of the existing therapies.