Complex Three-dimensional Structures Research Articles

Fabrication of Glass Microchannels Using Plant Roots and Nematodes

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

Pulmonary nodule detection based on IR-UNet + + .

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

RENDERING OF INHOMOGENEOUS VOLUMES USING PERTURBATION FUNCTIONS

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

Rhodium-Catalyzed Diastereo- and Enantioselective Divergent Annulations between Cyclobutanones and 1,5-Enynes: Rapid Construction of Complex C(sp3)-Rich Scaffolds.

Given the emerging demand to "escape from flatland" for drug discovery, synthetic methods that can efficiently construct complex three-dimensional structures with multi-stereocenters become increasingly valuable. Here, we describe the development of Rh(I)-catalyzed intramolecular annulations between cyclobutanones and 1,5-enyne groups to construct complex C(sp3)-rich scaffolds. Divergent reactivities are realized with different catalysts, and excellent diastereo- and enantioselectivity have been achieved. The use of (R)-H8-binap as the ligand favors forming the bis-bicyclic scaffolds with multiple quaternary stereocenters, while the (R)-segphos ligand prefers to generate the tetrahydro-azapinone products. Owing to the versatile reactivity of ketone moieties, these C(sp3)-rich scaffolds can be further functionalized. Experimental and computational mechanistic studies support a reaction pathway involving enyne-cyclometallation, 1,2-carbonyl addition, and then β-carbon elimination; the divergent reactivities are dictated by a product-determining Rh-alkyl migratory insertion step.

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

We have developed a method for constructing the geometry of a morphologically realistic human aorta, including the aortic root (Valsalva sinus), thoracic aorta, aortic arch with branches, abdominal aorta with bifurcation vessels. The creation of a three-dimensional model of the human aorta is necessary when planning surgical interventions, when performing numerical modeling of blood flow in the aorta. The anatomical structure of the aorta differs in different patients, especially in the presence of various pathologies (aneurysms, stenoses, aortic dissection). Creation of an individual human aorta model based on MRI, CT images requires time-consuming manual work of a highly computer skilled specialist. Presented is a simple method of building a 3D model of the human aorta. Initially, a 3D model of the aorta (or selected section of the aorta) of one patient is created. For this purpose, an analytical 3D model of this aorta is constructed from the raw model of the aorta. To build such an analytical aorta, it is necessary to divide the aorta into characteristic sections and specify defining parameters for each section. To build a model of another patient's aorta, a base model is taken and adjusted based on the individual features of the patient's aorta structure. At that, areas of pathology (stenoses and aneurysms) are added if necessary. Correction of the basic model requires much less time and effort than creating an aortic model of a particular patient from scratch. One of the key features of the technique is ease of use, eliminating the monotonous manual labor of building an individual patient's aorta. The resulting three-dimensional model of the aorta is fully ready for 3D modeling and printing on a 3D printer. Sections of the aorta are docked with the second order of smoothness (continuous second derivative between sections of the constructed aorta).

Experimental investigation and numerical modeling of laser powder bed fusion process-induced angle-dependent defects in strut-based lattice structure

The emergence of additive manufacturing technology has enabled the fabrication of advanced structures with intricate geometric topologies. However, additive manufacturing induces geometric defects in as-printed structures which may result in deviation from the parent material’s properties. The defects and impaired material properties greatly influence the performance of the fabricated structure. In this paper, the effect of build angle is investigated. The angle-dependency for the geometric defect distribution characteristics is verified through X-ray tomography. The mathematical relationship between the parent material’s properties and the build angle is established. A numerical model is developed for predicting the mechanical performance of laser powder bed fusion fabricated lattice structures proposed by using the experimental results. The positioning geometric defects are introduced into this model to achieve higher predicting accuracy. This work proposes a reliable and low-cost numerical analysis method based on the angle dependence and helps in predicting the mechanical performance of additive-manufactured complex three-dimensional lattice structures.

3D-Printable Cellular Composites for the Production of Recombinant Proteins.

The incorporation of living cells into materials promises both significant challenges and new possibilities. Although recent years have seen important advances in this field, there is still much to be learned about engineering interfaces between cells and materials. Here, we present a new class of 3D-printable materials, based on poly(N-hydroxymethylacrylamide) (PNHMAA), in which the spore-forming bacterium Bacillus subtilis is effectively cross-linked into the surrounding polymeric scaffold. After dehydration and subsequent re-swelling in nutrient-rich media, embedded cells and spores become metabolically active and are capable of heterologous protein production and secretion. Strikingly, the leak-free scaffold allows protein production while preventing escape of embedded cells. The successful construction of complex three-dimensional structures by stereolithographic printing of living PNHMAA composite materials suggests utility in a broad range of applications.

Trapezia Crabs That Dwell in Distinctive Day/Night Canopy Compartments of a Marine Animal Forest, Forage on Demersal Plankton

Canopies of branching corals harbor a wide range of sessile- and mobile-dwelling species that benefit from the physical compartments and the micro-environments created by the complex three-dimensional structures. Although different compartments within canopies are differentially used by inhabitant species, the distribution of mobile animals between coral canopy compartments are not fully explored. Here, we study Stylophora pistillata, a common branching coral in the Gulf of Eilat that harbors obligatory crabs from the family Trapezia. Two in situ surveys elucidated diel dynamics in compartmental distributions of Trapezia species within S. pistillata canopies compartments, associated with the crab’s body size and day/night activities. Whereas all crabs were found within sheltered spaces in the coral canopy understory or in the base during day hours, laboratory experiments revealed that nighttime distributions of small and large crabs (in middle and up compartments, respectively) are not intraspecific competition-borne, but rather, the outcome of preferred crab-size location for a novel feeding type, predation on demersal plankton. This study, thus, disclosed the importance of studying the coral’s three-dimensional structures and within canopies’ compartments for understanding the biology of dwelling species in the animal forests’ canopies.

Scalable Multi-Material Additive Manufacturing of Bioinspired Polymeric Material With Metallic Structures Via Electrically Assisted Stereolithography

Abstract Heterogeneous material systems consisting of metallic structures and polymer matrixes are of significance for applications such as integrated circuits, microelectromechanical devices, antennas, sensors, actuators, and metamaterials. Scaly-foot snail which lives in the deep ocean exhibits high strength and temperature resistance due to unique shells made of metal and polymer. Recently, different multi-material structures have been fabricated with metal deposition using multiple manufacturing processes. However, using these complicated hybrid processes is challenging to construct complexthree-dimensional (3D) structures of heterogeneous material with enhanced properties, high resolution, and time efficiency. Here, we establish a novel manufacturing strategy to build bioinspired hierarchical structures with heterogeneous material systems using electrically assisted stereolithography. The photocurable printing solution that can act as an electrolyte for charge transfer was developed, and the curing characteristic of the printing solution was further investigated. A fundamental understanding of the formation mechanism of metallic structures on the polymer matrix was studied through physics-based multi-scale modeling and simulations. The correlation between metallic structures morphology, printing solution properties, and printing process parameters, and their effects in building bioinspired hierarchical structures with heterogeneous materials were identified. Demonstrative test cases were built to verify the printing performance of the proposed approach. This research work will deliver a scalable additive manufacturing (AM) process that can facilitate various interesting applications based on bioinspired heterogeneous material and structures.

Evaluation of an Oxygen-Reduced Air Flooding Plugging System and Its Injection Method in the Honghe Oilfield

Oil recovery in a pilot test of gas flooding in the Honghe oilfield was greatly affected by the presence of fractures of various scales and the limited effect of a single plugging system. To elucidate the gas channeling behavior and identify the optimal injection method of oxygen-reduced air flooding in fractured tight oil reservoirs, foam and gel systems were selected to plug small and large fractures, respectively. Various methods of injecting oxygen-reduced air were studied through parallel core flooding tests to compare the gas channeling characteristics and changes in oil recovery during different plugging and displacement processes. Experimental methods including Waring blender, scanning electron microscopy, temperature resistance evaluation, and plugging performance and core flow evaluation were used in this study. The experimental results showed that the optimized FC-2 foam had the best foaming ability and half-life for the gas/liquid ratio of 1:1 and the mass fraction of 0.3%. In addition, the prepared gel had a complex and dense three-dimensional network structure, and the plugging rate was 98.17%. Finally, a displacement experiment showed that the combination of water, gel, FC-2 foam plugging system, and 5% oxygen-reduced air had the best plugging effect and gave the highest oil recovery. Compared with injecting oxygen-reduced air only, oil recovery from the small fracture core, large fracture core, and parallel core were improved by 19.71, 14.66, and 17.53%, respectively.

Approaches to benchmark and characterize in vitro human model systems.

In vitro human models, such as gastruloids and organoids, are complex three-dimensional (3D) structures often consist of cells from multiple germ layers that possess some attributes of a developing embryo or organ. To use these models to interrogate human development and organogenesis, these 3D models must accurately recapitulate aspects of their in vivo counterparts. Recent advances in single-cell technologies, including sequencing and spatial approaches, have enabled efforts to better understand and directly compare organoids with native tissues. For example, single-cell genomic efforts have created cell and organ atlases that enable benchmarking of in vitro models and can also be leveraged to gain novel biological insights that can be used to further improve in vitro models. This Spotlight discusses the state of current in vitro model systems, the efforts to create large publicly available atlases of the developing human and how these data are being used to improve organoids. Limitations and perspectives on future efforts are also discussed.

Numerical Simulation of Flow and Heat Transfer of a Discontinuous Single Started Helically Ribbed Pipe

In the present study, the turbulent flow field and the heat transfer in a single started helically ribbed pipe with a discontinuous rib are investigated. A large-eddy simulation (LES) technique is applied in a pipe section with cyclic boundary conditions. The aim of this study is to explain and further analyze the findings from the heat transfer measurements at such complex structures with the help of detailed flow simulations. The simulation results are validated with measurements at a Reynolds number of Re = 21,100 and a Prandtl number of Pr = 7 with water as fluid. The comparison clearly shows that the current method delivers accurate results concerning average flow field, turbulence quantities and local heat transfer. The results demonstrate that the applied method is capable of correctly simulating flows with heat transfer in complex three-dimensional structures. The overall heat transfer performance of the helically ribbed pipe with a discontinuous rib is compared to a smooth pipe and a continuous rib configuration. The impact of the interruption of the rib structure on pressure drop and heat transfer are analyzed in detail.

Polymer Models of Chromatin Imaging Data in Single Cells

Recent super-resolution imaging technologies enable tracing chromatin conformation with nanometer-scale precision at the single-cell level. They revealed, for example, that human chromosomes fold into a complex three-dimensional structure within the cell nucleus that is essential to establish biological activities, such as the regulation of the genes. Yet, to decode from imaging data the molecular mechanisms that shape the structure of the genome, quantitative methods are required. In this review, we consider models of polymer physics of chromosome folding that we benchmark against multiplexed FISH data available in human loci in IMR90 fibroblast cells. By combining polymer theory, numerical simulations and machine learning strategies, the predictions of the models are validated at the single-cell level, showing that chromosome structure is controlled by the interplay of distinct physical processes, such as active loop-extrusion and thermodynamic phase-separation.

Fabrication of Complex Three-Dimensional Structures of Mica through Digital Light Processing-Based Additive Manufacturing

Mica is a group of clay minerals that are frequently used to fabricate electrical and thermal insulators and as adsorbents for the treatment of cationic pollutants. However, conventional subtractive manufacturing has the drawback of poor three-dimensional (3D) shape control, which limits its application. In this study, we propose digital light processing (DLP)-based additive manufacturing (AM) as one of the most effective ways to address this drawback. Two major challenges for the ceramic DLP process are the production of a homogeneous and stable slurry with the required rheological properties and the maintenance of printing precision. The mica green body was fabricated using a 53 vol.% solid loading slurry through DLP, which exhibited good dimensional resolution under an exposure energy dose of 10 mJ/cm2. The precise, complex 3D structure was maintained without any defects after debinding and sintering at 1000 °C. The use of ceramic AM to overcome the shape-control limitations of mica demonstrated in this study offers great potential for expanding the applications of mica.

Printability Prediction in Projection Two-Photon Lithography Via Machine Learning Based Surrogate Modeling of Photopolymerization

Abstract Two-photon lithography (TPL) is a direct laser writing process that enables the fabrication of cm-scale complex three-dimensional polymeric structures with submicrometer resolution. In contrast to the slow and serial writing scheme of conventional TPL, projection TPL (P-TPL) enables rapid printing of entire layers at once. However, process prediction remains a significant challenge in P-TPL due to the lack of computationally efficient models. In this work, we present machine learning-based surrogate models to predict the outcomes of P-TPL to >98% of the accuracy of a physics-based reaction-diffusion finite element simulation. A classification neural network was trained using data generated from the physics-based simulations. This enabled us to achieve computationally efficient and accurate prediction of whether a set of printing conditions will result in precise and controllable polymerization and the desired printing versus no printing or runaway polymerization. We interrogate this surrogate model to investigate the parameter regimes that are promising for successful printing. We predict combinations of photoresist reaction rate constants that are necessary to print for a given set of processing conditions, thereby generating a set of printability maps. The surrogate models reduced the computational time that is required to generate these maps from more than 10 months to less than a second. Thus, these models can enable rapid and informed selection of photoresists and printing parameters during process control and optimization.

A 3D printable, highly stretchable, self-healing hydrogel-based sensor based on polyvinyl alcohol/sodium tetraborate/sodium alginate for human motion monitoring

Self-healing hydrogels have great application potential in the field of bio-sensors due to their self-healing, flexibility and excellent tensile properties. However, most hydrogel-based sensors are processed by template method, which is unable to fabricate complex three-dimensional (3D) structures, and limits the development of hydrogel-based sensor devices. A simple yet efficient one-pot method was proposed to fabricate polyvinyl alcohol/sodium tetraborate/sodium alginate hydrogel inks (SPB), also a fabricating process of self-healing hydrogel based on 3D printing technology has been proposed. The SPB hydrogel rapidly healed (<30 s) at room temperature, while its mechanical properties and conductivity also recovered quickly after healing. Besides, it could be used as wearable strain sensors, whose high stretchability (>2800 % strain) and sensitivity (gauge factor: 18.56 at 2000 % strain) could not only detect very large stretch deformations, but also detect the tiny pressure changes in the human body, such as finger flexion, knee flexion, and respiration. This study provides a method for the rapid fabrication of complex-structured hydrogel-based sensors, which is helpful for the hydrogel-based sensor applications in human motion detection and wearable devices.

Explosion suppression effect and mechanism analysis of ceramic foam in the horizontal pipe

ABSTRACT Ceramic foams are potential materials for explosion suppression due to their complex three-dimensional porous structure and strong wave absorption capabilities. The ability of ceramic foams to suppress methane/air explosion was investigated in a large-scale horizontal pipe. The factors of pore size and thickness of the ceramic foam were taken into consideration, and the explosion overpressure and explosion energy were compared and discussed collectively. Furthermore, mechanisms for the suppression of ceramic foams were also analyzed. Results indicated that ceramic foam has a good quenching effect on explosions compared to the conditions in an empty pipe. It can effectively decrease the explosion overpressure and explosive energy, thus limiting the flame propagation owing to insufficient fuel supply. The tendency for maximum explosion overpressure and explosion energy varied significantly by changing the thickness and pore size. It is worth noting that the attenuation rate of the maximum overpressure is generally greater than 50%, and the Al2O3 ceramic foam showed a better suppression performance than SiC. Additionally, the inhibitory effect is most obvious at 15 mm-20ppi Al2O3 and 30 mm-30ppi SiC, where the maximum explosion overpressure was reduced to 0.11 MPa and 0.19 MPa. However, the reduction of explosive energy is the combined result of the thickness and size of the pores. Overall, 15 mm Al2O3 and 30 mm SiC were more advantageous in suppressing gas explosions. This work supports the mechanism for preventing and suppressing gas explosions while using ceramic foam, and it might serve as a technological reference for the construction of explosion-proof devices. It is essential to avoid and control explosions in gas pipelines, thereby successfully enhancing the safety guarantee in gas pipeline transportation and engineering applications.

Phaleria macrocarpa Flavonoid as a Potent MMP-1 Inhibitor for Endometriosis Therapy: In silico Study

Introduction: Endometriosis is a gynaecological disorder in women and causes infertility. Several therapeutic were developed to reduce endometriosis cases, one of them was matrix metalloproteinase (MMP) inhibitor. This study investigated the potential activity of the flavonoids in Phaleria macrocarpa fruit as MMP1 inhibitors for endometriosis. Methods: In silico modelling was used in this study. Six flavonoid structures were retrieved from PubChem NCBI database. A targeted protein, MMP1 was taken out from Protein Data Bank with ID 1CGE and predicted the active sites. Six flavonoids and MMP1 was interacted by molecular docking using Molegro virtual Docker version 5 and analyzed using PyMol 2.2 and Discovery Studio version 21.1.1. Three-dimensional complex structure of flavonoids – MMP1 showed interaction in the same active sites and performed an amino acid residue Glu219 as catalytic site. Results: Six flavonoids of Phaleria macrocarpa were divided into two patterns and generated varied binding energy. Glycitin and Catechin 7-O-beta-D-xyloside showed low score of binding energy and depicted similar structure with four aromatic rings. 8-Prenylnaringenin performed lower binding energy than naringenin, eriodictyol, and 5-O-methylgenistein. Conclusion: In silico analysis suggested that six flavonoids compounds is potent as MMP1 inhibitor and might be interfered endometriosis pathophysiology. In vivo and in vivo investigations are required for further analysis.

Extracellular Matrix Coatings on Cardiovascular Materials—A Review

Vascular transplantation is an effective and common treatment for cardiovascular disease (CVD). However, the low biocompatibility of implants is a major problem that hinders its clinical application. Surface modification of implants with extracellular matrix (ECM) coatings is an effective approach to improve the biocompatibility of cardiovascular materials. The complete ECM seems to have better biocompatibility, which may give cardiovascular biomaterials a more functional surface. The use of one or several ECM proteins to construct a surface allows customization of coating composition and structure, possibly resulting in some unique functions. ECM is a complex three-dimensional structure composed of a variety of functional biological macromolecules, and changes in the composition will directly affect the function of the coating. Therefore, understanding the chemical composition of the ECM and its interaction with cells is beneficial to provide new approaches for coating surface modification. This article reviews novel ECM coatings, including coatings composed of intact ECM and biomimetic coatings tailored from several ECM proteins, and introduces new advances in coating fabrication. These ECM coatings are effective in improving the biocompatibility of vascular grafts.

Soft tissue reconstruction in traumatic nasal defects by forehead flap: A tertiary care centre experience

Forehead flap is the gold standard for nasal soft tissue reconstruction. The nose is a complex three-dimensional structure and along with the eyes, represents a major aesthetic focus of the face. The aim of this study is to review the use of forehead flap in nasal reconstruction and prospectively evaluate the outcome of treating nasal defects as an easy, effective and economical treatment in the Indian population.Material and Methods: This prospective study was conducted from March 2020 to May 2022. Patients with subtotal nasal defect who were above 18 years of age, and patients who were willing to give informed consent for treatment. Each participant underwent surgical debridement under loupe magnification combined with forehead flap cover after a full clinical assessment.Results: Twenty three participants were included in this study with an age range of 18–62 years with mean age (36.1±8.71). Out of these 6(26.1%) were female and 17(73.9%) were males. The defect were located over the dorsum and lateral nasal wall in 3 participants (13.1%), tip in 2(8.7%) patients, ala in 1(4.3%) patients and involved multiple subunit in 17(73.9%).Conclusion: The forehead flap represents the ideal reconstructive choice in patients with nasal defects. It has good textural, thickness and color match when compared with the recipient site tissues, with minor complications.