High Shape Retention Research Articles

A lumen-tunable triangular DNA nanopore for molecular sensing and cross-membrane transport

Synthetic membrane nanopores made of DNA are promising systems to sense and control molecular transport in biosensing, sequencing, and synthetic cells. Lumen-tunable nanopore like the natural ion channels and systematically increasing the lumen size have become long-standing desires in developing nanopores. Here, we design a triangular DNA nanopore with a large tunable lumen. It allows in-situ transition from expanded state to contracted state without changing its stable triangular shape, and vice versa, in which specific DNA bindings as stimuli mechanically pinch and release the three corners of the triangular frame. Transmission electron microscopy images and molecular dynamics simulations illustrate the stable architectures and the high shape retention. Single-channel current recordings and fluorescence influx studies demonstrate the low-noise repeatable readouts and the controllable cross-membrane macromolecular transport. We envision that the proposed DNA nanopores could offer powerful tools in molecular sensing, drug delivery, and the creation of synthetic cells.

KBStyle: Fast Style Transfer Using a 200 KB Network with Symmetric Knowledge Distillation.

Convolutional Neural Networks (CNNs) have achieved remarkable progress in arbitrary artistic style transfer. However, the model size of existing state-of-the-art (SOTA) style transfer algorithms is immense, leading to enormous computational costs and memory demand. It makes real-time and high resolution hard for GPUs with limited memory and limits the application on mobile devices. This paper proposes a novel arbitrary artistic style transfer algorithm, KBStyle, whose model size is only 200 KB. Firstly, we design a style transfer network where the style encoder, content encoder, and corresponding decoder are custom designed to guarantee low computational cost and high shape retention. Besides, the weighted style loss function is presented to improve the performance of style migration. Then, we propose a novel knowledge distillation method (Symmetric Knowledge Distillation, SKD) for encoder-decoder-based style transfer models, which redefines the knowledge and symmetrically compresses the encoder and decoder. With the SKD, the proposed style transfer network is further compressed by 14 times to achieve the KBStyle. Experimental results demonstrate that the proposed SKD method achieves comparable results with other SOTA knowledge distillation algorithms for style transfer. Besides, the proposed KBStyle achieves high-quality stylized images. And the inference time of the KBStyle on an Nvidia TITAN RTX GPU is only 20 ms when the resolutions of the content image and style image are both 2k-resolution (2048×1080). Moreover, the 200 KB model size of KBStyle is much smaller than the SOTA models and facilitates style transfer on mobile devices.

3D printed protein/polysaccharide food simulant for dysphagia diet: Impact of cellulose nanocrystals

With the intensified aging population, the demand for dysphagia diet is growing rapidly. The food texture in a dysphagia diet needs to be adjusted to be easy-to-swallow. Thus, most food is transformed in mashed form, which is not visually appealing and reduces patients’ appetite, resulting in a malnutrition risk. Three-dimensional (3D) food printing is an efficient technique to fabricate food designs with an attractive appearance and tailored nutritional content. In this work, we developed cellulose nanocrystal (CNC)-based protein/polysaccharide aqueous food inks using two commonly used proteins, namely gelatin B (GB) and whey protein isolate (WPI) for 3D printing, in combination with a polysaccharide frequently found in dysphagia diet, i.e. xanthan gum (XG). To ensure proper printability and shape retention, 2 wt% GB, 8 wt% XG and 8 wt% WPI were selected. Adding 1.0 wt% CNC in GB/XG and 1.5 wt% in WPI/XG improved the viscosity, yield stress and self-supporting ability of the inks, leading to higher shape fidelity right after printing and better shape retention for at least 96 h when stored at 4 °C. Additionally, the thermal stability of GB/XG mixed gels was also largely enhanced by CNC addition, resulting in a high shape retention with ∼90% of its original side area even at 50 °C. As a demonstration, some complex 3D shapes fabricated using both GB/XG/1.0CNC and WPI/XG/1.5CNC inks by single and multi-material DIW printing could also well retain their structures after heating at 50 °C for 5 min. Texture profile can also be tailored by both CNC concentrations and post-processing temperatures. Holding the temperature at 4 °C on the GB/XG/1.5CNC sample turned it from a non-approved classification into a level 5-minced and moist dysphagia diet formulation, according to the International Dysphagia Diet Standardization Initiative (IDDSI) test framework. This work provides rheological and processing guidelines for designing attractive food creations for dysphagic patients using 3D printing.

Structure maintainability of safflomin/betanin incorporated gelatin-chitooligosaccharide complexes based high internal phase emulsions and its combinational 3D printing

Safflomin A and betanin are incorporated into gelatin-chitooligosaccharide based complexes for stabilizing functional internal phase emulsions (HIPEs), which hold promise in 3D printing. Intermolecular interactions and good compatibility among gelatin, chitooligosaccharide and proper-content bioactive materials promoted the thermal stability (increased from 310.82 to 316.32 °C, or from 284.97 to 311.70 °C), dispersion stability (high UV absorbance) and microgel particles (around 358.67 or 408.30 nm) of complexes. The complexes illustrated great oil-water interfacial adsorption behaviors (kdiff = 0.29 mN m−1 s−0.5, π1600 = 21.71 mN/m) and dilatational viscoelasticity for interfacial membrane, implying high elasticity and interface stability. The strong droplet membrane and the compact gel network resulted in HIPEs to possess certain chemical stability (low color fading, e. g., under pH = 4), high centrifugation stability, shaking stability and freeze-thaw stability with low-diameter droplets. In addition to the excellent shear-thinning property (n1 < 1), HIPEs containing safflomin A or betanin had the systems with high degree of structuring (high η0 1.02 × 106 mPa s and 1.12 × 106 mPa s, respectively), excellent structure reversibility (high thixotropic index 7.62 and recovery index 71.76%; thixotropic index 6.87 and recovery index 77.29%, respectively), outstanding thixotropic performance (high thixotropic area 1872.01 Pa/s and 975.61 Pa/s, respectively), favorable self-supporting ability (recovery rates 92.01% and 94.61%, respectively), and high mechanical strength (yield stresses 21.32 Pa and 17.8 Pa after storage of 9 months), indicating the satisfactory structure maintainability. The screw-3D printing of HIPEs displayed high shape retention with low shape deviation (<5% for safflomin A- and betanin-based HIPEs), and certified the excellent printability. This study provides information for fabricating bioactive materials-HIPEs with desired structure, and manifests the potential of HIPEs in manufacturing functional, innovative food with high quality.

Effect of enzymatic-ultrasonic hydrolyzed chitooligosaccharide on rheology of gelatin incorporated yogurt and 3D printing

Bioactive chitooligosaccharide from enzymatic-ultrasonic hydrolysis of chitosan could work as modification agent for functionalizing the stirred yogurt and promoting the practical application. Microstructure, rheological property, texture, sensory quality , storage stability and 3D printability of the functionalized yogurt were investigated. Compared with chitosan, the obtained chitooligosaccharide has microscopic spherical shapes, more active groups and higher antioxidant activity . Introducing chitooligosaccharide-gelatin composite into yogurt in proper sequence could induce the great microscopic morphology, outstanding particle size distribution of yogurt and satisfactory gel structure. Rheology results further indicate that chitooligosaccharide could promote the structured matrix, great shearing-thinning performance, excellent deformation resistance, enhanced network, high thermo-reversible recuperative structure, great thixotropy and outstanding mechanical strength of yogurt. The fitted flow index and yield stress by Power-law and Herschel-bulkley illustrate the favorable shearing dependence, good extrudability, and satisfactory structure maintainability. Moreover, the prepared yogurt has satisfying texture and sensory quality, and could maintain probiotics at high level and thus great storage stability. The further 3D printed yogurt products on bread, and the further developed yogurts with bioactive ingredients suggest the promise in accelerating more types of nutritional dairy products with high quality and high application value. • Chitooligosaccharide is obtained from enzymatic-ultrasonic hydrolysis of chitosan. • Chitooligosaccharide enhances yogurt with good size distribution and gel structure. • Yogurt has great shear-thinning ability, elasticity, reversibility and thixotropy. • Yogurt possesses satisfying texture, sensory quality and favorable storage stability. • 3D printing of yogurts with high shape retention shows food customization potential.

3D Printing High‐Resolution Conductive Elastomeric Structures with a Solid Particle‐Free Emulsion Ink

Fabricating complex structures on micro‐ and mesoscales is a critical aspect in the design of advanced sensors and soft electronics. However, soft lithographic methods offer an important approach to fabricating such structures, the progress in the field of additive manufacturing (e.g., 3D printing) offers methods of fabrication with much more material complexity. The rheological complexity of the printing material, however, often dictates the limitations of printing. In particular, the challenges involved in synthesizing printing materials that can enable shape retention at smaller scales (&lt;100 μm), yet be conductive, limits many applications of 3D printing to soft microelectronics. Herein, a printing‐centered approach using a novel particle‐free conductive emulsion ink is presented. This approach separates the printing and polymerization of a conductive monomer (pyrrole) and renders a novel ink that is used to print filaments with heretofore impossible to realize 3D feature dimensions and build structures with high shape retention. The printability of the ink is evaluated, and post‐treatment properties assessed. Multidirectional strain sensors are printed using the emulsion ink to illustrate an exemplary application in soft electronics.

UV curing–assisted 3D plotting of core-shelled feedrod for macroporous hydroxyapatite scaffolds comprised of microporous hollow filaments

The present study demonstrates the manufacturing of macroporous hydroxyapatite (HA) scaffolds, comprised of microporous hollow filaments with high shape retention, by UV curing-assisted 3D plotting using a feedrod comprised of a photocurable HA shell and a carbon black (CB) core. Two types of scaffolds with different filament interspaces (0.5 mm and 1 mm) were produced by depositing core-shelled filaments extruded through a 1.07-mm-diameter nozzle with in situ polymerization process. Both scaffolds exhibited that the hollow HA filaments were produced after the removal of CB core by heat-treatment, while micropores in the HA walls were created as the replica of camphene-camphor crystals. Overall porosity and macroporosity obtained using a camphene-camphor content of 60 vol% increased from 74.3 vol% to 79.3 vol% and from 50.7 vol% and 64.6 vol%, respectively, with an increase in filament interspace sizes from 0.5 mm to 1 mm. Both scaffolds exhibited reasonably high compressive strengths (2.36 ― 3.58 MPa) and modulus (68–86 MPa).

Study of the fabric structure influence on the physical-mechanical and technological properties of knitted products

Three kinds of knitted fabrics with high shape retention capacity equipment LONG-XING SM 252 (China) 12-grade flat needle loom were produced, their technological characteristics were compared, and graphical records were supplied in this article based on experimental samples of knitted rubber fabric. The developed variants of knitted fabric differ from each other in pattern type, report, shape retention feature and a number of other indicators. Physical and mechanical properties of the obtained samples were determined experimentally on modern equipment installed in the testing laboratory of the Namangan Institute of Engineering Technology.

Photocurable ceramic/monomer feedstocks containing terpene crystals as sublimable porogen for UV curing-assisted 3D plotting

This study presents a novel strategy to construct ceramic structures comprised of microporous filaments using photocurable ceramic/monomer feedstocks containing terpene crystals as sublimable porogens for UV curing-assisted 3D plotting technique. The biphasic calcium phosphate (BCP) feedstock, composed of frozen terpene crystals surrounded by BCP/UDMA walls, could be favorably extruded through a fine nozzle and then effectively photopolymerized by UV light. Thus, green filaments with high shape retention could be obtained. In addition, a number of pores could be created in BCP filaments after removing terpene crystals via freeze-drying and the porosity could be tailored by adjusting terpene content in BCP feedstocks. This approach allowed for the construction of dual-scale porous structures comprising microporous filaments in a periodic pattern, with tailored overall porosities and compressive strengths. Several types of self-supporting structures were also successfully constructed using our approach.

Effects of spinning process and core yarn contents on yarn shape retention

Purpose In order to develop high shape retention yarn and investigate the effects of spinning process and core yarn contents on the shape retention of yarn, in this paper, three kinds of yarns, JC/T400 18.5tex (55.6dtex) core-spun yarn, JC/T400 18.5tex (44.4dtex) core-spun yarn and JC18.5tex pure cotton yarn were spun by using the complete condensing Siro-spinning technology. The paper aims to discuss these issues. Design/methodology/approach In this paper, the core-spun yarns were spun by using the complete condensing spinning and Siro-spinning technology. Two key spinning processes, yarn twist factor and core yarn pre-draft ratio, were optimized by using the orthogonal test method first. Then, via the variable control method, the position of the core yarn, the position of the bell mouth and the center distance between two bell mouths were optimized, respectively, and corresponding optimal spinning process of the three yarns was determined. Finally, the yarns were spun under the optimal process, and the performance of the spun yarns was tested and compared. Findings Results show that the yarn twist factor affects yarn strength and hairiness, the position of bell mouth affects the evenness and hairiness of the yarn mainly, and the position of the core yarn affects the coverage and hairiness of the yarn. For the Z-twist spinning, the core yarn enters the front roller from the left side of two strands center, which is beneficial to improve the covering effect of core yarn, and reduce the pilling phenomenon of the yarn. The contents of core yarn affect indicators of the yarn shape retention, such as yarn strength, elastic recovery and abrasion resistance. Originality/value The shape retention of yarns affects the shape retention of fabrics, and the production of yarn with high shape retention is a key step in achieving shape retention of fabrics. At present, there are little studies on the shape retention of yarns, most researchers shave focused on shape retention of fabrics. Using the complete condensing Siro-spinning method to spin the core-spun yarn can improve the quality of the yarn. Compared with traditional ring-spinning yarns, the addition of the core yarn can improve the shape retention of the yarn.

Method of Optimisation for Ambient Temperature Cured Sustainable Geopolymers for 3D Printing Construction Applications.

Since the initial introduction of geopolymers, these materials have been characterised as environmentally-friendly sustainable substitutes for ordinary Portland cement (OPC). There is a routine increase in the application of geopolymers, especially in advanced technologies. Because of its better rheological characteristics compared to OPC, geopolymers are appropriate materials for extrusion-based 3D printing technologies. This paper focuses on the optimisation of an ambient temperature cured geopolymer for 3D printing construction applications. The effects of mixture parameters, including the type of hydroxide solution (HS), the type of silicate solution (SS) and the mass ratio of SS to HS on the workability, extrudability, shape retention ability and mechanical performance of different geopolymer mixtures were investigated. Accordingly, an optimum mixture was identified for geopolymers cured at ambient temperatures. Mechanical properties of the optimised mixture, including flexural and compressive strengths, were measured in different directions with respect to the printed layers. Further, uniaxial tension tests were also conducted on the optimised mixture to measure its interlayer bond strength. The results showed that among the activators investigated, the sodium-based activator composed of sodium hydroxide and sodium silicate solutions, with a SiO2/Na2O ratio of 3.22, was the most effective activator, providing appropriate workability and extrudability, along with reasonable strength and a high shape retention ability. The acquired mechanical properties exhibited anisotropic behaviour in different testing direction. The strength of the interlayer bond was found to be adequate to avoid interfacial shear failure.

The preparation of hydrogel-like polyurethane using the graft polymerization of N,N-dimethylaminoethyl methacrylate and acrylic acid

The surface of polyurethane (PU) was modified by the graft polymerization of N,N-dimethylaminoethyl methacrylate (DAMA) and acrylic acid (AA) to enhance its water compatibility. Portions of poly(DAMA) and poly(AA) could be ionized by mutual acid–base neutralization and could notably improve the surface hydrophilicity of PU. The water contact angle, water absorption, and water vapor permeation test results jointly demonstrate the increase in water compatibility resulting from the inclusion of poly(DAMA) and poly(AA) in PU. The melting and glass transition temperatures of PU were not significantly influenced by the grafting of poly(DAMA) and poly(AA) onto PU. Small portions of the grafted poly(DAMA) and poly(AA) were involved in the cross-linking of PU, which sharply increased the shape recovery and the breaking tensile stress while maintaining high shape retention and breaking tensile strain.

Innovative in situ photocuring-assisted 3D plotting technique for complex-shaped ceramic architectures with high shape retention

We herein propose a novel type of additive manufacturing (AM) technique, denoted as “in situ photocuring-assisted 3D plotting”, which can rapidly solidify extruded green filaments comprised of ceramic powders and photocurable monomers using UV light during 3D plotting. To accomplish this, the rheological properties and photocuring behavior of the ceramic slurry were carefully tailored, particularly by using a mixture of diruethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) monomers as the photocurable vehicle. This innovative approach enabled the favorable extrusion of the ceramic slurry through a fine nozzle with high green strength after photocuring, and thus complex-shaped ceramic architectures with high shape retention could be constructed. As an example, a free-standing helical structure with a circular cross-section was successfully produced even without the use of any supporting materials. In addition, a porous ceramic scaffold with a tightly controlled porous structure could be produced.

Mechanical and Electrical Properties of Sulfur-Containing Polymeric Materials Prepared via Inverse Vulcanization.

Recently, new methods have been developed for the utilization of elemental sulfur as a feedstock for novel polymeric materials. One promising method is the inverse vulcanization, which is used to prepare polymeric structures derived from sulfur and divinyl comonomers. However, the mechanical and electrical properties of the products are virtually unexplored. Hence, in the present study, we synthesized a 200 g scale of amorphous, hydrophobic as well as translucent, hyperbranched polymeric sulfur networks that provide a high thermal resistance (>220 °C). The polymeric material properties of these sulfur copolymers can be controlled significantly by varying the monomers as well as the feed content. The investigated comonomers are divinylbenzene (DVB) and 1,3-diisopropenylbenzene (DIB). Plastomers with low elastic content and high shape retention containing 12.5%–30% DVB as well as low viscose waxy plastomers with a high flow behavior containing a high DVB content of 30%–35% were obtained. Copolymers with 15%–30% DIB act, on the one hand, as thermoplastics and, on the other hand, as vitreous thermosets with a DIB of 30%–35%. Results of the thermogravimetric analysis (TGA), the dynamic scanning calorimetry (DSC) and mechanical characterization, such as stress–strain experiments and dynamic mechanical thermal analysis, are discussed with the outcome that they support the assumption of a polymeric cross-linked network structure in the form of hyper-branched polymers.

Preparation and Investigation on Properties of Shape Memory Epoxy Modified by Hyperbranched Polyester

A series of hyperbranched polyester (HBPE) modified shape memory epoxies (SMEPs) were prepared for the first time. The materials’ toughness, mechanical properties and heat resistance were investigated by impact test, tensile test and DSC analysis. Besides, the possible effect of hyperbranched structure on SMEP’s shape memory property was studied by fold-deploy shape memory test. The results showed 5wt. % HBPE modified SMEP had the optimum properties. Its impact strength, tensile strength and elongation at break were increased by 51.8, 11.4 and 25.4%, respectively, without negative effect on SMEP’s heat resistance and shape memory property. All the samples had high shape retention ratio and 100% shape recovery ratio.

Thermal, mechanical and shape memory properties of shape memory epoxy resin

A series of shape memory epoxy resins (SMEPs) were prepared by epoxy and varying content of aromatic amine curing agent, for the purpose of application on space deployable structures. The thermal and mechanical properties of SMEPs were investigated by DSC, DMA and tensile test. Shape memory properties were also studied by an unusual method we called fold-deploy shape memory test. The effects of cross-linking density, recovery temperature and consecutive cycles on the shape memory properties were revealed through systematic variation of these factors. The results showed this series of SMEPs had high shape retention ratio (more than 99.5%) and shape recovery ratio (around 100%). Their T g varied from 44.7 °C to 145.3 °C, users could choose as individual requirement.

Fabrication of 316-L stainless steel micro parts by softlithography and powder metallurgy

This paper presents an approach to fabricate 316-L stainless steel micro parts with complex shapes using soft lithographical and powder metallurgical techniques. The process includes production of high quality deep micro SU-8 master moulds and their negative replicas in polydimethylsiloxane (PDMS). Then the PDMS soft moulds are filled with slurry containing superfine (< 4 um) stainless steel particles and binder. When the slurry is dry, green patterns are removed from the PDMS moulds before the patterns are de-bound and sintered in the tube furnace at 1200 in forming gas atmosphere. The resultant micro parts show high shape retention. The linear shrinkage of the sintered part is measured and found to be 17%.

Influence of emulsifiers on ice cream produced by conventional freezing and low-temperature extrusion processing

Ice cream at six different levels of emulsification was produced by freezing in a conventional scraped surface freezer and with a serial configuration of a conventional freezer followed by a low-temperature extruder. The aim was to examine the influence of emulsifiers on the process, since both emulsifier addition and low-temperature extrusion may have similar effects on promotion of colloidal structure in ice cream. Ice cream samples from both processes were analyzed for stiffness at draw, fat destabilization indices, melting performance, and microstructure. Low-temperature extrusion generally promoted enhanced fat destabilization, however, fat particle size and solvent extractable fat showed different dependencies on emulsification level from the two processing systems. Although solvent extractable fat reached high levels with increasing emulsification, fat particle size data suggested that fat agglomerate size was controlled by mechanical shearing. Significant difference between the two systems was seen also in the meltdown test, where melting rates for unemulsified and slightly emulsified mixes led to a very low melting rate and high shape retention in extruded ice cream. Scanning electron microscopy detected generally smaller air bubbles for extruded ice creams. Enhanced fat structuring around the air bubble and into the serum phase was also shown for unemulsified extruded samples.