Interconnected Fibers Research Articles

Innovative Approaches on the Estimation of the Effective Permittivity of Fibrous Media.

Estimating the effective permittivity of anisotropic fibrous media is critical for advancing electromagnetic applications, requiring detailed microstructural and orientation analyses. This study introduces innovative approaches for disclosing the orientation and microstructure of fibers, leading to mixing relations. It particularly focuses on two specific fiber configurations: 1. wave-curved fibers and 2. a collection of interconnected fibers. The first approach uses sinusoidal wave fibers, considering their curvature and direction. Conversely, the approach for the interconnected fibers operates on the principle of representing fibers as a collection of straight segments. Investigations on fibrous media for both approaches were performed using numerical calculations at the microwave frequency of 2.45 GHz. Each fibrous medium was treated as an effective medium by using fibers significantly smaller than the microwave wavelength. A thorough comparison was made between the proposed mixing relations, numerical data, and state-of-the-art mixing relations to assess their consistency and validity. The comparison of the proposed approaches with traditional models shows an improved accuracy of up to 70% and 8% for the real and imaginary components of the permittivity, respectively. Additionally, the root-mean-square errors were determined as 0.001 + j0.003 and 0.001 - j0.007 for the sinusoidal and interconnected straight fibers approaches, respectively. In addition, a woven alumina fabric was used to compare the experimental resonance frequency with that from simulations using the permittivity of the fabric estimated by the interconnected straight fibers approach. These findings advance the predictive accuracy of permittivity estimation in fibrous media, providing a robust foundation for engineering applications.

(Invited) Transparent Conductive Porous Supports for Photoelectrochemical and Photocatalytic H2 Production

Gas diffusion electrodes are essential components of common fuel and electrolysis cells that use gas phase reactants and products, but are typically made from graphitic carbon or metallic materials, which do not allow light transmittance, and thus limit the development of photoelectrode membrane assemblies for gas-phase solar fuel production. In this presentation, the application of solar H2 production from humid air is motivated and the simple and scalable preparation of transparent porous conductive substrates (TPCSs) using F-doped SnO2 (FTO) coated SiO2 interconnected fiber felt substrates is introduced. The resulting substrates have a porosity of 90 %, a roughness factor of 15.8 and a Young’s Modulus of 0.2 GPa. A sheet resistivity of 20 ± 3 Ω sq−1 and a loss of incident light of 41% at an illumination wavelength of 550 nm is found with FTO coating. The application of various semiconductors on the substrates was established including Fe2O3 (chemical bath deposition), BiVO4 (SILAR), CuSCN and Cu2O (electrodeposition), and semiconducting polymers (dip coating) and the liquid-phase photoelectrochemical performance commensurate with flat FTO substrates was confirmed. Gas phase H2 production was demonstrated with a polymer semiconductor photocathode membrane assembly at 1-Sun photocurrent density on the order of 1 mA cm–2 and Faradaic efficiency of 40%. Finally, the prospects for using the TPCSs as supports for photocatalysts are discussed.

Strong adsorption Fe[sbnd]N[sbnd]C catalytic cathode for 50,000 cycles aqueous zinc-iodine batteries

Aqueous zinc-iodine batteries have garnered increasing attention due to their low cost and high safety. However, their practical application is impeded by sluggish iodine redox reaction kinetics and the “shuttle effect” of polyiodides, which result in poor rate performance and limited cycled life. Here, we developed N-doped porous carbon fiber derived from Prussian blue and polyacrylonitrile (PAN) as a self-supporting cathode material for zinc-iodine batteries. The material demonstrates a high iodine adsorption capacity in the electrolyte solution. Density Function Theory (DFT) calculations indicate that the prepared materials demonstrate good catalytic activity. Furthermore, the interconnected carbon fiber network, characterized by high conductivity and a large specific surface area, facilitates rapid electron transport and ion diffusion. Consequently, the zinc-iodine battery demonstrates outstanding rate performance (148mAh g−1 at a high current density of 10 A g−1) and a long cycling life of 50,000 cycles, with a capacity retention rate of 72.1 %. Additionally, the battery achieves an impressive calendar life of 8 months and 23 days.

Assessment of some egg quality parameters and chorion ultrastructure characterization in Atlantic salmon (Salmo salar)

Farmed salmonid production requires oocytes and embryos of high quality to supply the increasing market demand; achieving this depends primarily on the management of females and gametes. The chorion of the fertilized egg is a crucial structure for embryo protection; however, it is still poorly studied in some fish species. The object of the present study was to evaluate some parameters of oocyte quality and embryonic development in S. salar, and to characterize the chorion at the ultrastructural level in oocytes and embryos at different stages up to hatching by scanning electron microscopy (SEM). The samples (oocytes and embryos) were obtained from five mature females (4 years old, 9.75 ± 0.86 kg) of S. salar. The results show 32% (20%; 64%) of oocytes with yolk clots, a hydration percentage of 17% (11.1%; 23.3%) and a significant increase in embryo hardness at 12 accumulated thermal units (ATU). A mean fertility rate of 77% (60%; 93%) was recorded. The survival rates were 72% (20%; 100%) and 73% (32%; 92%) for 130 and 318 ATU, respectively. The values of symmetrical blastomeres were high, 65% (45%; 80%); however, the rate of spine deformities was also high at 42.4% (22%; 71%). Several significant correlations were observed between the parameters assessed: there were high-positive correlations between the hydration percentage and blastomere symmetry (r = 0.89), between oocyte hardness and spine deformities (r = 0.88), and between embryo hardness at 130 and 318 ATU (r = 0.97); there were also strong correlations between symmetry and survival rate at 130 ATU (r = 0.95) and between symmetry and survival rate at 318 ATU (r = 0.96). In the ultrastructural analysis, the SEM images revealed that the outer layer of the chorion of both oocytes and fertilized eggs, through development to hatching, exhibits a granular pattern. In contrast, the inner layer is composed of numerous interconnected fibres that form a complex network, absent in the hatching area. Both outer and inner layers show numerous pore canals. The pores in the outer layer are covered by plugs, and are larger than those in the inner layer. The information generated in this study is useful to complement understanding of the biology of S. salar eggs; however, given the ultrastructural variability of the chorion, further studies are needed to expand on these findings.

Binding mechanism in bio-briquette prepared with wheat straw and lignite by mechanical thermal expression process

ABSTRACT In this study, bio-briquette was prepared with lignite and wheat straw by mechanical thermal expression (MTE) process and analyzed using an optical microscope (OM), scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. Under the combined action of thermal and mechanical energy, the binding mechanism between lignite and biomass in bio-briquette was discussed. Results showed that the compressive strength of bio-briquette increased with the increase of pressure and temperature, which positively affected the bonding of material particles. Lignite particles were wrapped into the network formed by interconnected fibers of different lengths. During the MTE process, the liquid bridges were built among the biomass undergoing glass transition, water, and partially melted lignite, which became solid bridges after briquette formation, enhancing the compressive strength of bio-briquette.

Electrospun Na3MnTi(PO4)3/C film: A multielectron-reaction and free-standing cathode for sodium-ion batteries

With the continuous advancement of renewable energy sources, sodium-ion batteries are currently regarded as highly promising technologies for large-scale electric energy storage. The compound Na3MnTi(PO4)3 has garnered significant attention owing to its exceptional theoretical capacity, robust structural stability, and abundant availability of resources. Herein, hierarchical carbon-decorated Na3MnTi(PO4)3 nanofibers are synthesized via a feasible electrospinning technique followed by pyrolysis, effectively addressing the issue of poor electronic conductivity in phosphate cathodes. The free-standing Na3MnTi(PO4)3/C electrode serves as a cathode for sodium-ion batteries, exhibiting exceptional electronic conductivity and superior Na+ transport capability. Moreover, it demonstrates an impressive reversible capacity of 171.4 mA h g−1 at 0.2C and exhibits outstanding cyclic stability with a capacity retention of 63.7 % after 6300 cycles at 1C. The full cell, assembled with independent Na3MnTi(PO4)3/C cathode and hard carbon anode, exhibits a reversible capacity of 153.7 mA h g−1 at a current density of 10 mA g−1. The in-situ synthesis of nanomaterial particles within interconnected porous nanocarbon fibers can effectively enhance the materials' poor electronic conductivity, thereby further improving their cyclic stability and Na+ transport kinetics.

Controlling Electrodeposition in Nonplanar High Areal Capacity Battery Anodes via Charge Transport and Chemical Modulation.

Controlling the morphological evolution of electrochemical crystal growth in battery anodes is of fundamental and practical importance, particularly towards realizing practical, high-energy batteries based on metal electrodes. Such batteries require highly reversible plating/stripping reactions at the anode to achieve a long cycle life. While conformal electrodeposition and electrode reversibility have been demonstrated in numerous proof-of-concept experiments featuring moderate to low areal capacity (≤3 mA h/cm2) electrodes, achieving high levels of reversibility is progressively challenging at the higher capacities (e.g., 10 mA h/cm2), required in applications. Nonplanar, "3D" electrodes composed of electrically conductive, porous substrates are conventionally thought to overcome trade-offs between reversibility and capacity because they hypothetically "host" the electrodeposits in an electronically conducting framework, providing redundant pathways for electron flow. Here, we challenge this hypothesis and instead show that a nonplanar substrate with moderate electrical conductivity (ideally, with an electrical conductance similar to the ionic conductance of the electrolyte) and composed of a passivated cathode-facing surface efficiently regulates electro-crystallization. In contrast, an architecture with a high intrinsic electrical conductivity or with a high electrical conductivity coating on the front surface results in dominantly out-of-plane growth, making the 3D architecture in effect function as a 2D substrate. Using Zn as an example, we demonstrate that interconnected carbon fiber substrates coated by SiO2 on the front and Cu on the back successfully ushers electroplated Zn metal into the 3D framework at a macroscopic length scale, maximizing use of the interior space of the framework. The effective integration of electrodeposits into the 3D framework also enables unprecedented plating/stripping reversibility >99.5% at high current density (e.g., 10 mA/cm2) and high areal capacities (e.g., 10 mA h/cm2). Used in full-cell Zn||NaV3O8 batteries with stringent N/P ratios of 3:1, the substrates are also shown to enhance cycle life.

Rational engineering WO3-X/CNTs@carbon fiber membrane for the high-efficient produce H2O2 via electrochemical two-electron water oxidation route

The electrochemical two-electron water oxidation reaction (2e-WOR) offers a promising avenue for hydrogen peroxide (H2O2) production. It is crucial to design electrocatalysts with high selectivity, yield, resource abundance, and environmental friendliness. In this paper, as a new generation 2e-WOR electrocatalyst, the WO3-X/CNTs@carbon fiber membrane nanostructure with abundant oxygen-rich vacancy (OV) has been discovered by a series of test techniques including XRD, FE-SEM, TEM, FT-IR, Raman and XPS, comprising interconnected carbon nanotubes and carbon fibers enveloped in WO3 nanorods with oxygen-rich vacancies. By comparing the specific surface area of WO3-x/CNTs@carbon fiber membrane at different temperatures, it was observed that the maximum value is 44.09 m2/g when the mass ratio of AMT to PAN was 3:2 at 600 °C. Furthermore, the WO3-X/CNTs@carbon fiber membrane can be directly utilized as an independent electrode. The electrochemical performance test revealed that the Faraday efficiency of the WO3-X/CNTs @CF-600-2 can reach 54 % (2.48 V vs RHE (reversible hydrogen electrode)), while the H2O2 yield can achieve 10.3 μmol· min−1·cm−2, nearly ten times higher than that of pure WO3. Furthermore, the stability testing demonstrated that after 12 h, the WO3-X/CNTs @CF-600-2 exhibited excellent stability with minimal change in its Faraday efficiency. This enhancement is attributed to the improved selectivity of WO3, excellent electrical conductivity, and mass transfer performance of carbon fiber. Finally, we proposed a mechanism for 2e-WOR and provided some perspectives on this reaction along with summarizing recent discoveries.

Flexible self-supporting interconnected cobalt sulfide nanosheets enable high-loading and long-cycling Li-S batteries with high areal capacity

Lithium-sulfur batteries (LSB) with high theoretical specific capacity/energy density still face some practical challenges, for instance shuttle effect and sluggish redox kinetics, which leads to rapid capacity decay. To overcome these challenges, herein, a porous and flexible sulfur host composed of interconnected Co9S8 nanosheets grown on carbon cloth was constructed. The interconnected carbon fiber skeleton and porous conductive Co9S8 nanosheets can not only provide abundant electron/ion-transport channels, but also offer adequate void to accommodate volume expansion of sulfur, thus ensuring high sulfur utilization and remarkable cycle stability of electrode. Meanwhile, the abundant adsorption and catalytic sites provided by Co9S8 nanosheets can effectively inhibit dissolution of polysulfides and improve conversion kinetics of polysulfides, effectively suppressing “shuttle effect”. The Co9S8-CC/Li2S6 electrode achieves high discharge capacity (1315.1 mAh g−1, 0.1C), excellent rate capability (872.4 mAh g−1, 2C) and outstanding cyclic stability (decay of 0.02 %/cycle over 1500 cycles, 2C).

Sintered Electrospun Fibrous Electrodes via Compression and Laser Perforation for Redox Flow Battery

The principal sources of new renewable energy, such as solar and wind power, depend strongly on the weather conditions, leading to the unstable electric power supply. Energy storage systems (ESS) has been developed to address this problem. One of the most promising technologies for energy storage device is redox flow batteries due to its high capacity and design flexibility. In particular, the vanadium redox flow battery is considered as a next-generation battery because of its safety and high efficiency, but not yet widely deployed owing to its low power density. The carbonized electrospun fibrous materials have been utilized as electrodes to overcome the flaw, because of their high specific surface area for reaction, high porosity to support flow and diffusion, and good electrical conductivity through the interconnected fibers. Typically, smaller fiber is preferential due to the exponential increase of surface area, but the small pores among the fibers reduce the permeability, limiting the electrolyte transportation or increasing parasitic pumping costs. In this study, flow battery electrodes made of electrospun carbon fibers were synthesized by applying compression during the stabilization stage. The objective was to create flow battery electrodes with higher volumetric surface area to support the electrochemical reaction while retaining the permeability. A porosity reduction of 12% was attained by this method, yielding a 50% increase of volumetric surface area, while the in-plane permeability and tortuosity were found to remain consistent. In addition, the holes perforated by a carbon dioxide laser addressed the issue of low through-plane permeability caused by the compacted fibers. All electrospun samples outperformed commercial carbon mats in flow cell tests. The compressed samples showed markedly better performance in the activation region but showed serious mass transport polarization at higher current density. The laser perforations significantly eliminated this flaw, yielding the best performance over the entire range of current density. Figure 1

Unveiling moisture transport mechanisms in cellulosic materials: Vapor vs. bound water.

Natural textiles, hair, paper, wool, or bio-based walls possess the remarkable ability to store humidity from sweat or the environment through "bound water" absorption within nanopores, constituting up to 30% of their dry mass. The knowledge of the induced water transfers is pivotal for advancing industrial processes and sustainable practices in various fields such as wood drying, paper production and use, moisture transfers in clothes or hair, humidity regulation of bio-based construction materials, etc. However, the transport and storage mechanisms of this moisture remain poorly understood, with modeling often relying on an assumption of dominant vapor transport with an unknown diffusion coefficient. Our research addresses this knowledge gap, demonstrating the pivotal role of bound water transport within interconnected fiber networks. Notably, at low porosity, bound water diffusion dominates over vapor diffusion. By isolating diffusion processes and deriving diffusion coefficients through rigorous experimentation, we establish a comprehensive model for moisture transfer. Strikingly, our model accurately predicts the evolution of bound water's spatial distribution for a wide range of sample porosities, as verified through magnetic resonance imaging. Showing that bound water transport can be dominant over vapor transport, this work offers a change of paradigm and unprecedented control over humidity-related processes.

Highly Flexible, Durable, Thermally Stable Multi-Functional Carbon Fabric Applications for Wearable Electronics

In recent years, wearable heaters have attracted widespread attention for applications in personal heating systems and healthcare management, such as thermotherapy of textiles/clothing. In addition, flexible gas sensors are important components of wearable electronic devices used for human safety and healthcare applications. However, the current low flexibility and poor stability of the materials limit their use. In this paper, among various textile materials, the carbon fabric based high-efficiency flexible heater with its own excellent conductivity, which does not contain additives from the manufacturing state, and a sensor using the same. In order to evaluate the performance of the heater, the heating temperature and power according to the applied voltage were analyzed. Also, the temperature distribution of the carbon fabric was observed using a thermal camera. The highly flexible fabric heater is based on a uniformly interconnected carbon fiber network that efficiently and quickly heats the heater with low input power. In addition, it presents a new carbon fabric gas sensor composed of pure carbon fiber itself without additives. The carbon fabric shows a sensitive response to NO2 (24.4%@5ppm) at room temperature, and with an extreme bending radius of 3mm, it shows excellent mechanical reliability against repeated deformations over 1,000 bending cycles. The carbon fabric sensors are extremely flexible and durable even after bending, providing a stable resistance to the sensor base material. The results could be attractive to development of flexible, room temperature operable fabric based wearable gas sensing platforms.

Colloidal Nanoplatelets‐Based Soft Matter Technology for Photonic Interconnected Networks: Low‐Threshold Lasing and Polygonal Self‐Coupling Microlasers

AbstractSoft matter‐based microlasers are widely regarded as excellent building blocks for realizing photonic interconnected networks in optoelectronic chips, owing to their flexibility and functional network topology. However, the potential of these devices is hindered by challenges such as poor lasing stability, high lasing threshold, and gaps in knowledge regarding cavity interconnection characteristics. In this study, the first demonstration of a high‐quality, low‐threshold nanoplatelets (NPLs)‐based polymer microfiber laser fabricated using capillary immersion techniques and its photonic interconnected networks are presented. CdSe/CdS@Cd1‐xZnxS core/buffer shell@graded‐shell NPLs with high optical gain characteristics are adopted as the gain medium. The study achieves a lasing threshold below 14.8 µJ cm−2, a single‐mode quality (Q)‐factor of ≈5500, and robust lasing stability in the fabricated NPLs‐based microfibers. Furthermore, the study pioneers the exploration of polygonal self‐coupling microlasers and the optical characteristics of their interconnected fiber network. Based on the signal generation mechanism observed in the photonic networks, an interconnected NPLs‐based fiber network structure achieving single‐mode lasing emission and laser mode modulation is successfully designed. The work contributes a novel method for realizing microlasers fabricated via soft‐matter technologies and provides a key foundation and new insights for unit design and programming for future photonic network systems.

Lightweight Soft Conductive Composites Embedded with Liquid Metal Fiber Networks

AbstractLiquid metal composites are promising soft conductors for applications in soft electronics, sensors, and soft robotics. Existing liquid metal composites usually have a high‐volume fraction of liquid metal, which not only increases the density but also the material cost. Future applications in soft electronics and robotics highly demand liquid metal composites with low density and high conductivity for large‐scale, low‐cost, lightweight, and more sustainable applications. In this work, lightweight and highly conductive composites embedded with liquid metal fiber networks are synthesized. This new paradigm of liquid metal composites consists of an interconnected liquid metal fiber network embedded in a compliant rubber matrix. The liquid metal fiber network serves as an ultra‐lightweight conductive pathway for electrons. Experiments indicate that this soft conductive composite also possesses nearly strain‐insensitive conductance and superior cyclic stability. Potential applications of the composite films as stretchable interconnects, electrodes, and sensors are demonstrated.

Construction of lotus stem-like Li3VO4 wrapped on carbon fibers via chemical lithiation promoting interfacial dynamics for capacitive lithium storage

Oxides based on vanadium redox couple, such as orthorhombic Li3VO4, has drawn great attentions due to its high theoretical capacity and moderate operating voltage. However, the rate property is largely hindered by the slow interfacial dynamics of Li3VO4. Here we synthesized the lotus stem-like Li3VO4 wrapped in N-doped carbon fibers (Li3VO4/C NF) stemmed from the chemical lithiation of V2O3/C NF. The knobbly Li3VO4 rooted in the interconnected carbon fibers provides abundant active sites and well-developed conductive networks. Thus, this anode delivers high specific capacity of 558.9 mAh g−1 at 0.2 A g−1 and excellent rate capacity of 419 mAh g−1 at 2 A g−1 sustaining 900 cycles with an average potential of 0.7 V vs. Li+/Li. Furthermore, the kinetic analysis reveals that the pseudocapacitance dominants the lithium storage process and the favorable interfacial ion and electronic transport is responsible for the enhanced rate performance. The full cell (Li3VO4/C NF||LiFePO4) also shows a competitive performance for commercialization. This work boosts the development of vanadium-based anode materials with desired electrochemical properties meeting devices requirements.

(Invited) Photoelectrode Membrane Assemblies with Transparent Conductive Gas Diffusion Layers for Solar Fuel Production

Gas diffusion electrodes are essential components of common fuel and electrolysis cells that use gas phase reactants and products, but are typically made from graphitic carbon or metallic materials, which do not allow light transmittance, and thus limit the development of photoelectrode membrane assemblies for gas-phase solar fuel production. In this presentation, the application of solar H2 production from humid air is motivated and the simple and scalable preparation of transparent gas-diffusion layers using F-doped SnO2 (FTO) coated SiO2 interconnected fiber felt substrates is introduced. The resulting substrates have a porosity of 90 %, a roughness factor of 15.8 and a Young’s Modulus of 0.2 GPa. A sheet resistivity of 20 ± 3 Ω sq−1 and a loss of incident light of 41% at an illumination wavelength of 550 nm is found with FTO coating. The application of various semiconductors on the substrates was established including Fe2O3 (chemical bath deposition), CuSCN and Cu2O (electrodeposition), and semiconducting polymers (dip coating) and the liquid-phase photoelectrochemical performance commensurate with flat FTO substrates was confirmed. Finally, gas phase H2 production was demonstrated with a polymer semiconductor photocathode membrane assembly at 1-Sun photocurrent density on the order of 1 mA cm–2 and Faradaic efficiency of 40%.

Controllable synthesis of composite electrode material to enhance the electrochemical performance of supercapacitors

Cobalt oxide (Co3O4), cobalt oxide/reduced graphene oxide (Co3O4/rGO), and cobalt oxide/reduced graphene oxide/polyaniline (Co3O4/rGO/PANI) ternary composites with varying PANI concentrations are created using the hydrothermal route and in-situ polymerization of aniline monomer. X-ray diffractometer XRD results reveal the presence of cubic Co3O4, hexagonal rGO, and emeraldine salt structure of PANI. SEM images reveal dense interconnected PANI fibers and rGO clusters across the quasi-cube-like Co3O4 structure. (Co3O4/rGO)/PANI (80%:20%) composites offer excellent optoelectronic properties with 2.32 eV bandgap. As the concentration of PANI increases, the (Co3O4/rGO)/PANI (40%:60%) exhibits 1673 dielectric constant, making it suitable for various electronics and electrical engineering applications. The electrochemical findings show that the (Co3O4/rGO)/PANI (60%:40%) based electrode has an exceptional capacitance of 3103.27 F/g at 2 A/g, maintaining a capacitance of nearly 92% after 10,000 continuous cycles. The composite also exhibits an extraordinary specific capacitance of 2101.3 F/g at 5 mV/s and the lowest ohmic resistance. These findings support the use of the (Co3O4/rGO)/PANI (60%:40%) ternary composite as a valuable and innovative electrode for supercapacitors.

Conductive Bacterial Nanocellulose-Polypyrrole Patches Promote Cardiomyocyte Differentiation.

The low endogenous regenerative capacity of the heart, added to the prevalence of cardiovascular diseases, triggered the advent of cardiac tissue engineering in the last decades. The myocardial niche plays a critical role in directing the function and fate of cardiomyocytes; therefore, engineering a biomimetic scaffold holds excellent promise. We produced an electroconductive cardiac patch of bacterial nanocellulose (BC) with polypyrrole nanoparticles (Ppy NPs) to mimic the natural myocardial microenvironment. BC offers a 3D interconnected fiber structure with high flexibility, which is ideal for hosting Ppy nanoparticles. BC-Ppy composites were produced by decorating the network of BC fibers (65 ± 12 nm) with conductive Ppy nanoparticles (83 ± 8 nm). Ppy NPs effectively augment the conductivity, surface roughness, and thickness of BC composites despite reducing scaffolds' transparency. BC-Ppy composites were flexible (up to 10 mM Ppy), maintained their intricate 3D extracellular matrix-like mesh structure in all Ppy concentrations tested, and displayed electrical conductivities in the range of native cardiac tissue. Furthermore, these materials exhibit tensile strength, surface roughness, and wettability values appropriate for their final use as cardiac patches. In vitro experiments with cardiac fibroblasts and H9c2 cells confirmed the exceptional biocompatibility of BC-Ppy composites. BC-Ppy scaffolds improved cell viability and attachment, promoting a desirable cardiomyoblast morphology. Biochemical analyses revealed that H9c2 cells showed different cardiomyocyte phenotypes and distinct levels of maturity depending on the amount of Ppy in the substrate used. Specifically, the employment of BC-Ppy composites drives partial H9c2 differentiation toward a cardiomyocyte-like phenotype. The scaffolds increase the expression of functional cardiac markers in H9c2 cells, indicative of a higher differentiation efficiency, which is not observed with plain BC. Our results highlight the remarkable potential use of BC-Ppy scaffolds as a cardiac patch in tissue regenerative therapies.

PANI/Ti3C2Tx composite nanofiber-based flexible conductometric sensor for the detection of NH3 at room temperature

The rational design of sensing materials with distinct morphologies and compositions is important to construct outstanding flexible gas sensors. Herein, a mesh polyaniline (PANI)/Ti3C2Tx composite nanofiber-based flexible sensor was constructed by electrospinning of PANI and few-layer Ti3C2Tx nanosheets. Sensing results indicated that this novel PANI/Ti3C2Tx flexible sensor demonstrated much higher NH3 sensing response (2.3-fold improvement @ 20 ppm) in comparison with the sensor based on pure PANI nanofibers at 25 °C. Under different bending angles (maximum compression of 150°) and different bending times (maximum bending of 3200 times), the PANI/Ti3C2Tx flexible sensor maintained steady sensing behavior towards 20 ppm NH3, which reflected its good flexible bending stability. The PANI/Ti3C2Tx flexible sensor also exhibited good selectivity, repeatability, as well as good long-term stability. The improvement of NH3 sensing properties can be ascribed to the formation of Schottky junctions between PANI and Ti3C2Tx nanosheets, improved protonation degree of PANI, and the special three-dimensional mesh fiber structure. Our work revealed that the PANI/Ti3C2Tx composite nanofibers with interconnected mesh fiber structure have great potential to construct flexible NH3 sensors.

Bandwidth Capacity Analysis on Fiber Optic Networks for E - learning at Pakuan University

Pakuan University (UNPAK) currently has 6 faculties for undergraduate programs, vocational schools, graduate, and post-graduate programs, with an interconnected fiber optic network. The management of the fiber optic network is carried out by Putik as O & M in collaboration with Moratel as the internet connection provider with a bandwidth of 550 Mbps. Analyzing the bandwidth capacity of the fiber optic network is crucial for the implementation of e-learning at Pakuan University. E-learning plays an important role in supporting the teaching and learning process during the Covid-19 pandemic, whether online or remote learning. Based on the daily user recapitulation, it is known that e-learning usage peaks between 08.50 – 10.30 Western Indonesian Time on an usual Monday with 6,505 users in total. The Faculty of Social and Cultural Sciences (FISIB) holds the highest usage of 143.23 Mbps, along with other faculties which exceeds the predetermined capacity of 40 Mbps each. This caused the Simple Queue method to experience access delays of even Request Time Out (RTO) conditions. Therefore, the Simple Queue method is no longer adequate, making the Queue Tree method the better option.