Transcatheter atrial septal defect closure late after completion of biventricular circulation in patients with pulmonary atresia intact ventricular septum or critical pulmonary stenosis.

OBJECTIVE: This study aimed to explore anatomical and hemodynamic features of atrial septal defect, which was treated by transcatheter device closure late after completion of biventricular circulation in patients with pulmonary atresia and intact ventricular septum (PAIVS) or critical pulmonary stenosis (CPS). METHODS: We studied echocardiographic and cardiac catheterization data, including defect size, retroaortic rim length, single or multiple defects, the presence of malalignment atrial septum, tricuspid and pulmonary valve diameters, and cardiac chamber sizes, in patients with PAIVS/CPS who underwent transcatheter closure of atrial septal defect (TCASD), and compared to control subjects. RESULTS: A total of 173 patients with atrial septal defect, including 8 patients with PAIVS/CPS, underwent TCASD. Age and weight at TCASD were 17.3 ± 18.3 years and 36.6 ± 13.9 kg, respectively. There was no significant difference in defect size (13.7 ± 4.0 vs. 15.6 ± 5.2 mm, p = 0.317) and the retro-aortic rim length (3.7 ± 4.3 vs. 3.6 ± 0.3.1 mm, p = 0.948) between the groups; however, multiple defects (50% vs. 5%, p < 0.001) and malalignment atrial septum (62% vs. 14%. p < 0.001) were significantly frequent in patients with PAIVS/CPS compared to control subjects. The ratio of pulmonary to systemic blood flow in patients with PAIVS/CPS was significantly lower than that in the control patients (1.2 ± 0.4 vs. 2.0 ± 0.7, p < 0.001); however, four out of eight patients with atrial septal defect associated with PAIVS/CPS had right-to-left shunt through a defect, who were evaluated by the balloon occlusion test before TCASD. The indexed right atrial and ventricular areas, the right ventricular systolic pressure, and mean pulmonary arterial pressure did not differ between the groups. After TCASD, the right ventricular end-diastolic area remained unchanged in patients with PAIVS/CPS, whereas it significantly decreased in control subjects. CONCLUSIONS: Atrial septal defect associated with PAIVS/CPS had more complex anatomy, which would be a risk for device closure. Hemodynamics should be individually evaluated to determine the indication for TCASD because PAIVS/CPS encompassed anatomical heterogeneity of the entire right heart.

Evaporative Dry Powders Derived from Cellulose Nanofiber Organogels to Fully Recover Inherent High Viscosity and High Transparency of Water Dispersion.

Water containing low amounts of cellulose nanofiber (CNF) is widely used as a thickening agent owing to its three unique properties: high transparency, viscosity, and controllable viscosity based on the shear rate. CNF dry powders are used to reduce the transportation and storage costs or expand applications as a thickening agent. Herein, the preparation of CNF dry powders that can be used to obtain redispersions while maintaining the aforementioned properties is reported. In this regard, the dehydration and vaporization procedures for a CNF water dispersion without using additives are discussed. When dry powders are prepared by removing water by boiling, their redispersions do not exhibit all their unique properties because of dense aggregations. However, when their redispersions are vigorously stirred to break the dense aggregations, they become transparent, although they do not recover their initial viscosity. Freeze-dried powders recover all their initial properties after redispersion. Nevertheless, their large volume does not reduce the transportation and storage costs. When the liquid is evaporated from the solvent-exchanged CNF organogels, their redispersions also fully recover all their properties. Furthermore, the evaporative dry powders with dense small volumes and good handling contribute to reducing the transportation and storage costs.

Biaxially stretchable silver nanowire conductive film embedded in a taro leaf-templated PDMS surface.

A biaxially wave-shaped polydimethylsiloxane (PDMS) surface was developed simply by using a taro leaf as the template. The resulting leaf-templated PDMS (L-PDMS) possesses a micro-sized curved interface structure, which is greatly beneficial for the exact embedding of a silver nanowire (AgNW) network conductive film covering the L-PDMS surface. The intrinsically curved AgNW/L-PDMS film surface, without any dangling nanowire, could prevent the fracture of AgNWs due to stretching stress even after cyclic stretching. More importantly, it also exhibited a biaxial stretchability, which showed ultra-stable resistance after continuous stretching for 100 cycles each in X- and Y-directions. This biaxially stretchable AgNW/L-PDMS film could extend the application fields in stretchable electronics.

Stretchable and transparent electrodes based on patterned silver nanowires by laser-induced forward transfer for non-contacted printing techniques.

Silver nanowires (AgNWs) are excellent candidate electrode materials in next-generation wearable devices due to their high flexibility and high conductivity. In particular, patterning techniques for AgNWs electrode manufacture are very important in the roll-to-roll printing process to achieve high throughput and special performance production. It is also essential to realize a non-contact mode patterning for devices in order to keep the pre-patterned components away from mechanical damages. Here, we report a successful non-contact patterning of AgNWs-based stretchable and transparent electrodes by laser-induced forward transfer (LIFT) technique. The technique was used to fabricate a 100% stretchable electrode with a width of 200 µm and electrical resistivity 10-4 Ωcm. Experiments conducted integrating the stretchable electrode on rubber substrate in which LED was pre-fabricated showed design flexibility resulting from non-contact printing. Further, a patterned transparent electrode showed over 80% in optical transmittance and less than 100 Ω sq-1 in sheet resistance by the optimized LIFT technique.

Chemically-modified cellulose paper as a microstructured catalytic reactor.

We discuss the successful use of chemically-modified cellulose paper as a microstructured catalytic reactor for the production of useful chemicals. The chemical modification of cellulose paper was achieved using a silane-coupling technique. Amine-modified paper was directly used as a base catalyst for the Knoevenagel condensation reaction. Methacrylate-modified paper was used for the immobilization of lipase and then in nonaqueous transesterification processes. These catalytic paper materials offer high reaction efficiencies and have excellent practical properties. We suggest that the paper-specific interconnected microstructure with pulp fiber networks provides fast mixing of the reactants and efficient transport of the reactants to the catalytically-active sites. This concept is expected to be a promising route to green and sustainable chemistry.

Nanofibrillar chitin aerogels as renewable base catalysts.

We demonstrate the fabrication of chitin nanofibril aerogels and their successful application as base catalysts for the production of useful chemicals. Squid-pen chitin nanofibrils (ChNF) with primary C2-amine groups on their crystalline surfaces were fabricated into highly porous aerogels with high specific surface areas up to 289 m(2) g(-1) using freeze-drying or a supercritical drying process. The prepared ChNF aerogel was used in the aqueous Knoevenagel-condensation reaction and acted as a highly efficient base catalyst, suggesting that the combination of the nanofibrous aerogel structure and primary C2-amines exposed on the crystalline ChNF surface was effective for continuous flow catalysis. Because the ChNF aerogel can be easily prepared from abundant and renewable chitin present in nature, this strategy is a gateway to promoting and conducting green and sustainable chemistry.

Electrodeposition of cellulose nanofibers as an efficient dehydration method.

Dehydration of a cellulose nanofiber (CNF)/water dispersion requires large amounts of energy and time due to the high hydrophilicities and high specific surface areas of the CNFs. Various dehydration methods have been proposed for CNF/water dispersions; however, an efficient dehydration method for individually dispersed CNFs is needed. Here, electrodeposition of CNFs was evaluated as a dehydration method. Electrodeposition at a DC voltage of 10 V on a 0.2 wt% CNF/water dispersion resulted in a concentration of ∼1.58 wt% in 1 h. The dehydration energy efficiency was ∼300 times greater than that of dehydration by evaporation. The concentrated CNF hydrogels recovered after electrodeposition were redispersed with a simple neutralization process, and clear transparent films were obtained by drying after redispersion. This work provides a new method for dehydration and reuse of individually dispersed CNF/water dispersions and provides new insights into control of the hierarchical structures of CNFs by electrodeposition.

Cu salt ink formulation for printed electronics using photonic sintering.

We formulate copper salt (copper formate/acetate/oleate) precursor inks for photonic sintering using high-intensity pulsed light (HIPL) based on the ink's light absorption ability. The inks can be developed through controllable crystal field splitting states (i.e., the ligand weights and their coordination around the metal centers). The inks' light absorption properties are extremely sensitive to the carbon chain lengths of the ligands, and the ink colors can drastically change. From the relationship between the ratios of C/Cu and the required sintering energies, it is possible to ascertain that the integral absorbance coefficients are strongly correlated with the photonic sintering behavior. These results suggest that the ink absorbance properties are the most important factors in photosintering. The wires formed by sintered copper formate complex ink via the HIPL method showed good electronic conduction, achieving a low resistivity of 5.6 × 10(-5) Ω cm. However, the resistivity of the wires increased with increasing contains carbon chain length of the inks, suggesting that large amounts of residual carbon have negative effects on both the wire's surface morphology and the electrical conductivity. We find in this study that high light absorptivity and low carbon inks would lead to a lower environmental load in future by reducing both energy usage and carbon oxide gas emissions.

Transparent, conductive, and printable composites consisting of TEMPO-oxidized nanocellulose and carbon nanotube.

Ultrastrong, transparent, conductive and printable nanocomposites were successfully prepared by mixing single-walled carbon nanotubes (CNTs) with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) with abundant sodium carboxyl groups on the crystalline nanocellulose surfaces. The surface-anionic cellulose nanofibrils had reinforcing and nanodispersing effects on the CNTs both in water used as the dispersed medium and in the dried composite film, providing highly conductive and printable nanocomposites with a small amount of CNTs. TOCNs are therefore expected as an effective flexible matrix that can be used as an alternative to conventional polymers for various electrical materials, when nanocomposited with CNTs and also graphene. Our findings provide a promising route to realize green and flexible electronics.

Clearly transparent and air-permeable nanopaper with porous structures consisting of TEMPO-oxidized cellulose nanofibers.

Optically transparent materials that are air permeable have potentially numerous applications, including in wearable devices. From the perspective of sustainable development, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers with widths of 3-4 nm have attracted considerable attention as starting materials for the preparation of clearly transparent nanofiber paper (denoted as conventional nanopaper). However, conventional nanopaper that is prepared from a water dispersion of TEMPO-oxidized cellulose nanofibers by direct drying exhibits poor air permeability owing to its densely packed layered structure. In this study, we prepared a clearly transparent and air-permeable nanopaper by applying filtration-based solvent exchange from high-surface-tension water to low-surface-tension ethanol and hexane, followed by drying under continuous vacuum filtration. The resulting hexane-exchanged nanopaper had a porous structure with individually dispersed and thin nanofiber networks and interlayer pore spaces. Owing to the tailored porous structures, the hexane-exchanged nanopaper provides similar clear transparency (total light transmittance and haze at 600 nm: 92.9% and 7.22%, respectively) and 106 times higher air permeability (7.8 × 106 mL µm m-2 day-1 kPa-1) compared to the conventional nanopaper. This study will facilitate the development of clearly transparent and air-permeable nanopapers to extend their functional applications.

All-Nanochitin-Derived, Super-Compressible, Elastic, and Robust Carbon Honeycombs and Their Pressure-Sensing Properties over an Ultrawide Temperature Range.

Elastic carbon aerogels show great potential for various applications but are often hindered by structure-derived fatigue failure, weak elasticity with low compressibility, and low stress and height retention. Herein, we demonstrate a super-elastic and fatigue-resistant nanochitin-derived carbon honeycomb with honeycomb-like anisotropic microstructures and carbon-based molecular structures, which was tailored by optimizing the nanochitin concentrations and carbonization temperatures. The carbon honeycomb fabricated at a nanochitin concentration of 1.0 wt % and a carbonization temperature of 900 °C demonstrated anisotropic honeycomb channels, nanofibrous network channel walls with few cracks, and weak interactions between the carbonized nanochitin, which afforded high compressibility with up to 90% strain and complete recovery. In particular, the carbon honeycomb provided good fatigue resistance with high stress and height retentions of 87 and 94%, respectively, after more than 10,000 compression cycles at 90% strain. Moreover, the tailored anisotropic honeycomb channels and molecular structures endowed the carbon honeycomb with elasticity even under severe conditions, such as exposure to flame (approximately 1000 °C) and liquid nitrogen (approximately -196 °C). Owing to these properties, the nanochitin-derived carbon honeycomb could act as a high-sensitivity pressure sensor for a wide working pressure range of 0-185.5 kPa and ultrawide temperature range of -196-600 °C. This study can provide a promising route to develop all-biomass-derived, super-elastic, and fatigue-resistant carbon materials for pressure sensing under harsh conditions and for versatile electronic applications.

Chitin-Derived Nitrogen-Doped Carbon Nanopaper with Subwavelength Nanoporous Structures for Solar Thermal Heating.

Sustainable biomass-derived carbons have attracted research interest because of their ability to effectively absorb and convert solar light to thermal energy, a phenomenon known as solar thermal heating. Although their carbon-based molecular and nanoporous structures should be customized to achieve enhanced solar thermal heating performance, such customization has insufficiently progressed. In this study, we transformed a chitin nanofiber/water dispersion into paper, referred to as chitin nanopaper, with subwavelength nanoporous structures by spatially controlled drying, followed by temperature-controlled carbonization without any pretreatment to customize the carbon-based molecular structures. The optimal carbonization temperature for enhancing the solar absorption and solar thermal heating performance of the chitin nanopaper was determined to be 400 °C. Furthermore, we observed that the nitrogen component, which afforded nitrogen-doped carbon structures, and the high morphological stability of chitin nanofibers against carbonization, which maintained subwavelength nanoporous structures even after carbonization, contributed to the improved solar absorption of the carbonized chitin nanopaper. The carbonized chitin nanopaper exhibited a higher solar thermal heating performance than the carbonized cellulose nanopaper and commercial nanocarbon materials, thus demonstrating significant potential as an excellent solar thermal material.

CO2-laser-induced carbonization of calcium chloride-treated chitin nanopaper for applications in solar thermal heating.

Remarkable progress has been made in the development of carbonized chitin nanofiber materials for various functional applications, including solar thermal heating, owing to their N- and O-doped carbon structures and sustainable nature. Carbonization is a fascinating process for the functionalization of chitin nanofiber materials. However, conventional carbonization techniques require harmful reagents, high-temperature treatment, and time-consuming processes. Although CO2 laser irradiation has progressed as a facile and second-scale high-speed carbonization process, CO2-laser-carbonized chitin nanofiber materials and their applications have not yet been explored. Herein, we demonstrate the CO2-laser-induced carbonization of chitin nanofiber paper (denoted as chitin nanopaper) and investigate the solar thermal heating performance of the CO2-laser-carbonized chitin nanopaper. While the original chitin nanopaper was inevitably burned out by CO2 laser irradiation, CO2-laser-induced carbonization of the chitin nanopaper was achieved by pretreatment with calcium chloride as a combustion inhibitor. The CO2-laser-carbonized chitin nanopaper exhibits excellent solar thermal heating performance; its equilibrium surface temperature under 1 sun irradiation is 77.7 °C, which is higher than those of the commercial nanocarbon films and the conventionally carbonized bionanofiber papers. This study paves the way for the high-speed fabrication of carbonized chitin nanofiber materials and their application in solar thermal heating toward the effective utilization of solar energy as heat.

Spatial exosome analysis using cellulose nanofiber sheets reveals the location heterogeneity of extracellular vesicles.

Extracellular vesicles (EVs), including exosomes, are recognized as promising functional targets involved in disease mechanisms. However, the intravital heterogeneity of EVs remains unclear, and the general limitation for analyzing EVs is the need for a certain volume of biofluids. Here, we present cellulose nanofiber (CNF) sheets to resolve these issues. We show that CNF sheets capture and preserve EVs from ~10 µL of biofluid and enable the analysis of bioactive molecules inside EVs. By attaching CNF sheets to moistened organs, we collect EVs in trace amounts of ascites, which is sufficient to perform small RNA sequence analyses. In an ovarian cancer mouse model, we demonstrate that CNF sheets enable the detection of cancer-associated miRNAs from the very early phase when mice did not have apparent ascites, and that EVs from different locations have unique miRNA profiles. By performing CNF sheet analyses in patients, we identify further location-based differences in EV miRNA profiles, with profiles reflecting disease conditions. We conduct spatial exosome analyses using CNF sheets to reveal that ascites EVs from cancer patients exhibit location-dependent heterogeneity. This technique could provide insights into EV biology and suggests a clinical strategy contributing to cancer diagnosis, staging evaluation, and therapy planning.

One-Pot Hierarchical Structuring of Nanocellulose by Electrophoretic Deposition.

The orientation control and the formation of hierarchical structures of nanoscale components, such as bionanofibers and nanosheets, have attracted considerable research interest with the aim of achieving sophisticated functional materials. Herein, we report a simple and flexible strategy for constructing sophisticated hierarchical structures through electrophoretic and electrochemical deposition. Cellulose nanofibers (CNFs), which are used as model materials, are deposited on an anode in an aqueous dispersion and seamlessly oriented from horizontal to vertical relatively to the electrode by adjusting the applied voltage between the electrodes. The oriented CNF hydrogels not only exhibit anisotropic mechanical properties but also form complex orientations and hierarchical structures, such as cartilage- and plant stem-like configurations in response to electrode shape and applied voltage. This simple and flexible technique is expected to be applicable to various materials and contribute to a wide range of fields that include biomimicry, functional nanomaterials, and sustainable and functional moldings.

Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano-Micro-Macro Trans-Scale Design.

Semiconducting nanomaterials with 3D network structures exhibit various fascinating properties such as electrical conduction, high permeability, and large surface areas, which are beneficial for adsorption, separation, and sensing applications. However, research on these materials is substantially restricted by the limited trans-scalability of their structural design and tunability of electrical conductivity. To overcome this challenge, a pyrolyzed cellulose nanofiber paper (CNP) semiconductor with a 3D network structure is proposed. Its nano-micro-macro trans-scale structural design is achieved by a combination of iodine-mediated morphology-retaining pyrolysis with spatially controlled drying of a cellulose nanofiber dispersion and paper-crafting techniques, such as microembossing, origami, and kirigami. The electrical conduction of this semiconductor is widely and systematically tuned, via the temperature-controlled progressive pyrolysis of CNP, from insulating (1012 Ω cm) to quasimetallic (10-2 Ω cm), which considerably exceeds that attained in other previously reported nanomaterials with 3D networks. The pyrolyzed CNP semiconductor provides not only the tailorable functionality for applications ranging from water-vapor-selective sensors to enzymatic biofuel cell electrodes but also the designability of macroscopic device configurations for stretchable and wearable applications. This study provides a pathway to realize structurally and functionally designable semiconducting nanomaterials and all-nanocellulose semiconducting technology for diverse electronics.

Polydopamine Doping and Pyrolysis of Cellulose Nanofiber Paper for Fabrication of Three-Dimensional Nanocarbon with Improved Yield and Capacitive Performances.

Biomass-derived three-dimensional (3D) porous nanocarbons have attracted much attention due to their high surface area, permeability, electrical conductivity, and renewability, which are beneficial for various electronic applications, including energy storage. Cellulose, the most abundant and renewable carbohydrate polymer on earth, is a promising precursor to fabricate 3D porous nanocarbons by pyrolysis. However, the pyrolysis of cellulosic materials inevitably causes drastic carbon loss and volume shrinkage. Thus, polydopamine doping prior to the pyrolysis of cellulose nanofiber paper is proposed to fabricate the 3D porous nanocarbons with improved yield and volume retention. Our results show that a small amount of polydopamine (4.3 wt%) improves carbon yield and volume retention after pyrolysis at 700 °C from 16.8 to 26.4% and 15.0 to 19.6%, respectively. The pyrolyzed polydopamine-doped cellulose nanofiber paper has a larger specific surface area and electrical conductivity than cellulose nanofiber paper that without polydopamine. Owing to these features, it also affords a good specific capacitance up to 200 F g-1 as a supercapacitor electrode, which is higher than the recently reported cellulose-derived nanocarbons. This method provides a pathway for the effective fabrication of high-performance cellulose-derived 3D porous nanocarbons.

Direct determination of the degree of fibrillation of wood pulps by distribution analysis of pixel-resolved optical retardation.

We propose a new methodology for direct evaluation of the degree of fibrillation of fibrillating pulp suspensions through the pixel-resolved retardation distribution. Through simple normalization by just injecting a pulp suspension with a certain concentration into a quartz flow channel with a constant cross-sectional shape, the degree of fibrillation (i.e., the degree of bundling of cellulose molecular chains) can be directly mapped by the retardation gradation, reflecting locally high retardation (pulp fibers), smaller retardation (balloons on fibrillating pulps), and much smaller retardation close to water (dispersed nanofibers). Both the average retardation and standard deviation are found to be the direct indicators of the degree of fibrillation. We envision that the proposed methodology will become the future standard for determining the degree of fibrillation by the retardation distribution, and it will pave the way for more precise control of pulp fibrillation and more sophisticated applications of cellulose nanofiber suspensions.

Thermal Conductivity Analysis of Chitin and Deacetylated-Chitin Nanofiber Films under Dry Conditions.

Chitin, a natural polysaccharide polymer, forms highly crystalline nanofibers and is expected to have sophisticated engineering applications. In particular, for development of next-generation heat-transfer and heat-insulating materials, analysis of the thermal conductivity is important, but the thermal conductivity properties of chitin nanofiber materials have not been reported. The thermal conductivity properties of chitin nanofiber materials are difficult to elucidate without excluding the effect of adsorbed water and analyzing the influence of surface amino groups. In this study, we aimed to accurately evaluate the thermal conductivity properties of chitin nanofiber films by changing the content of surface amino groups and measuring the thermal diffusivity under dry conditions. Chitin and deacetylated-chitin nanofiber films with surface deacetylation of 5.8% and 25.1% showed in-plane thermal conductivity of 0.82 and 0.73 W/mK, respectively. Taking into account that the films had similar crystalline structures and almost the same moisture contents, the difference in the thermal conductivity was concluded to only depend on the amino group content on the fiber surfaces. Our methodology for measuring the thermal diffusivity under conditioned humidity will pave the way for more accurate analysis of the thermal conductivity performance of hydrophilic materials.

Thermal diffusivity modulation driven by the interfacial elastic dynamics between cellulose nanofibers.

Thermal transport modulating materials show great potential to address the heat problems in a wide range of engineering fields. However, tuning the thermal conductivity of solid-state materials is practically difficult because it requires specific or extreme stimulation, such as chemical composition change, a phase transition, or large applied fluctuations, to change the internal bulk structures. Here, we report reversible switching of the in-plane thermal diffusivity of densely packed cellulose nanofiber (CNF) films by ∼15% by simple mechanical strain as small as 0.3%. From analysis of the stress relaxation profiles and the different bulk densities of the CNF films, the interfacial elastic dynamics between the strongly hydrogen bonded CNFs were found to exhibit thermal diffusivity modulation by tuning the interfacial thermal resistance, rather than changing the bulk structure of the CNFs. Our concept of interfacial-elasticity-driven thermal diffusivity switching has the potential to enhance the on/off rate and extensibility toward practical use owing to the high designability of the interfacial conditions.