Spinning Technique Research Articles

A single 1-min brain MRI scan for generating multiple synthetic image contrasts in awake children from quantitative relaxometry maps.

Diagnostically adequate contrast and spatial resolution in brain MRI require prolonged scan times, leading to motion artifacts and image degradation in awake children. Rapid multi-parametric techniques can produce diagnostic images in awake children, which could help to avoid the need for sedation. To evaluate the utility of a rapid echo-planar imaging (EPI)-based multi-inversion spin and gradient echo (MI-SAGE) technique for generating multi-parametric quantitative brain maps and synthetic contrast images in awake pediatric participants. In this prospective IRB-approved study, awake research participants 3-10years old were scanned using MI-SAGE, MOLLI, GRASE, mGRE, and T1-, T2-, T2*-, and FLAIR-weighted sequences. The MI-SAGE T1, T2, and T2* maps and synthetic images were estimated offline. The MI-SAGE parametric values were compared to those from conventional mapping sequences including MOLLI, GRASE, and mGRE, with assessments of repeatability and reproducibility. Synthetic MI-SAGE images and conventional weighted images were reviewed by a neuroradiologist and scored using a 5-point Likert scale. Gray-to-white matter contrast ratios (GWRs) were compared between MI-SAGE synthetic and conventional weighted images. The results were analyzed using the Bland-Altman analysis and intra-class correlation coefficient (ICC). A total of 24 healthy participants aged 3years to 10years (mean ± SD, 6.5 ± 1.9; 12 males) completed full imaging exams including the 54-s MI-SAGE acquisition and were included in the analysis. The MI-SAGE T1, T2, and T2* had biases of 32%, -4%, and 23% compared to conventional mapping methods using MOLLI, GRASE, and mGRE, respectively, with moderate to very strong correlations (ICC=0.49-0.99). All MI-SAGE maps exhibited strong to very strong repeatability and reproducibility (ICC=0.80 to 0.99). The synthetic MI-SAGE had average Likert scores of 2.1, 2.1, 2.9, and 2.0 for T1-, T2-, T2*-, and FLAIR-weighted images, respectively, while conventional acquisitions had Likert scores of 3.5, 3.6, 4.6, and 3.8 for T1-, T2-, T2*-, and FLAIR-weighted images, respectively. The MI-SAGE synthetic T1w, T2w, T2*w, and FLAIR GWRs had biases of 17%, 3%, 7%, and 1% compared to the GWR of images from conventional T1w, T2w, T2*w, and FLAIR acquisitions respectively. The derived T1, T2, and T2* maps were correlated with conventional mapping methods and showed strong repeatability and reproducibility. While synthetic MI-SAGE images had greater susceptibility artifacts and lower Likert scores than conventional images, the MI-SAGE technique produced synthetic weighted images with contrasts similar to conventional weighted images and achieved a ten-fold reduction in scan time.

Polymer stabilized cholesteric liquid crystals enhanced by functional nanofibers loaded with CuS NPs and ATO NPs for efficient smart windows and advanced infrared camouflage/anti-counterfeiting technologies

The development of multifunctional smart windows with infrared anti-counterfeiting capabilities is a key research priority. However, achieving both high visible light (VIS) transparency and effective near-infrared (NIR) blocking remains a significant challenge. In this study, a multi-field responsive polymer stabilized cholesteric liquid crystal (PSCLC) smart window was successfully prepared. By adjusting the electric field, the smart window enables controlled adjustment of incident VIS and NIR light for temperature control. Optimization of polymerization conditions and nanofiber loading enhanced the bandwidth reflectance from 256 to 507 nm. The smart window employs an optimized drive scheme for coordinated IR modulation via direct current (DC). The copper sulfide (CuS) and antimony tin oxide (ATO) nanoparticles were loaded in the PSCLC system using electrostatic spinning technique. The loading of nanoparticles using nanofibers greatly increased the number of nanoparticles compared to direct doping of nanoparticles. Therefore, the nanofibers loaded with nanoparticles greatly enhanced the infrared shielding ability and electrical response of the system. In addition, the enhancement of nanofibers also improves the thermal and electrical durability of the PSCLC smart window, and the controlled distribution of nanofibers results in a highly flexible and reliable infrared anti-counterfeiting smart window. This research provides the development of multifunctional liquid crystal smart windows with infrared light modulation, camouflage and anti-counterfeiting functions.

Smart chitosan-based nanofibers for real-time monitoring and promotion of wound healing

Timely healing of acute wounds and stopping wound chronicity are current and future priorities in wound therapy. It is urgent and relevant to develop a wound dressing that has antimicrobial and monitors the wound microenvironment in real time. In this study, quaternary ammonium chitosan (HTCC) was selected as the antimicrobial agent and CS/PEO/HTCC nanofiber membranes (CPHs) were prepared by electrostatic spinning technique. The nanofiber membrane (CPH91) with the best antimicrobial performance was screened by the disk diffusion method and drug susceptibility testing by dilution method, and its antimicrobial effect on S. aureus was better than that of E. coli. Subsequently, functional carbon dots (CDs) were synthesized by solvothermal method and doped into CPH91 nanofibers by electrospinning. A good linear relationship between pH value (5.0–8.0) and the fluorescence intensity of CDs was observed. In addition, the nanofibers (CPH91@CDs) had good morphology, hydrophilicity, and biocompatibility. Changes in fluorescence intensity of CPH91@CDs at different pH (5.0–8.0) were monitored and converted into RGB values that were linearly fitted to pH value. Finally, the potential of CPH91@CDs of improving wound healing and instantaneously controlling wound healing process was confirmed by an infected wound model (S. aureus) on the back of SD rats.

Flexible Silk Fibroin-Based Triboelectric Nanogenerators with Thermal Management Capabilities for Temperature Regulation and Self-Powered Monitoring.

Flexible triboelectric nanogenerators (TENGs) are highly advantageous for human-centered monitoring due to their self-sustaining energy and high output performance. However, temperature fluctuations that limit thermal comfort have hindered their practical advancement. In this study, flexible titanium dioxide-silk fibroin@phase change microcapsule nanofiber films (TiO2-SF@PCM NFs) were successfully developed using an efficient electro-blown spinning (EBS) technique, with exceptional triboelectric output and superior temperature regulation capabilities. Our design achieved cooling effects of approximately 10 °C and provided thermal insulation of about 2.2 °C. Notably, applying the TiO2-SF@PCM NFs to a model car produced an impressive cooling effect of 22 °C. Furthermore, a single-electrode triboelectric sensor based on TiO2-SF@PCM NFs achieved a peak output power of ∼272 μW/m2 and exceptional stability over 1000 output cycles. This study presents a promising strategy for the scalable production of flexible composite nanofiber films, effective in both temperature regulation and self-powered monitoring, highlighting their potential for use as thermal comfort sensors.

Influence of the grain size on the martensitic transformation and strain nanodomains in the Ti-Hf-Ni-Cu shape memory alloy

The martensitic transformation and strain nanodomain were studied in the Ti40.7Hf9.5Ni44.8Cu5 shape memory alloy, whose grain size varied from 130 μm to 160 nm. The largest average grain size (600 μm in length and 130 μm in diameter) was found in the CAST sample. The grains with the smallest size (160 nm) formed during the crystallisation of thin ribbons obtained by the melt spinning technique from the Ti40.7Hf9.5Ni44.8Cu5 ingot (labelled as RIBBON). The average grain size (16 μm) was observed in the sample subjected to high-pressure torsion and post-deformation annealing (labelled as HPT). It was found that the CAST and HPT samples included the NiTi-based matrix and the Ti2Ni-type precipitates, whereas the RIBBON sample contained the NiTi-based matrix only. Regardless of the grain size, all samples underwent the B2 ↔ B19’ transformation on cooling and heating. A decrease in grain diameter from 130 μm to 160 nm decreased the transformation temperatures by more than 100 °C but did not affect the sequence of the transformation. The strain nanodomains formed in all samples on cooling prior to the forward martensitic transformation. The smaller the grain size, the larger the temperature range of the strain nanodomain existence. On heating of HPT and RIBBON samples, the B19 phase transformed to the B2 phase with strain nanodomains, which disappeared only on heating over 120 °C. The influence of grain size on the martensitic transformation and strain nanodomains was analysed from the thermodynamics approach.

Post-spin Stretch Improves Mechanical Properties, Reduces Necking, and Reverts Effects of Aging in Biomimetic Artificial Spider Silk Fibers.

Recent biotechnological advancements in protein production and development of biomimetic spinning procedures make artificial spider silk a promising alternative to petroleum-based fibers. To enhance the competitiveness of artificial silk in terms of mechanical properties, refining the spinning techniques is imperative. One potential strategy involves the integration of post-spin stretching, known to improve fiber strength and stiffness while potentially offering additional advantages. Here, we demonstrate that post-spin stretching not only enhances the mechanical properties of artificial silk fibers but also restores a higher and more uniform alignment of the protein chains, leading to a higher fiber toughness. Additionally, fiber properties may be reduced by processes, such as aging, that cause increased network entropy. Post-spin stretching was found to partially restore the initial properties of fibers exposed aging. Finally, we propose to use the degree of necking as a simple measure of fiber quality in the development of spinning procedures for biobased fibers.

Silk and Silkworm: (Re)discussion on the Origin and Early History of Using Silk Fibres

Discussions on the origin of silk utilisation usually focus on the origin of discovering filaments, ignoring the existence and availability of short fibres. Among these studies, some arguments with evidence of silkworms have inserted a preconception that silkworm rearing is certainly related to silk utilisation, ignoring the possibility that human ancestors might have reared silkworms for other reasons before they knew how to use silk fibres. Considering the difficulties in obtaining raw materials, the complexity of the production processes, and archaeological evidence for the early use of silk, it seems probable that silk was utilised first in the form of short fibres and these fibres were processed with the spinning technique. By analysing the relationship between silk reeling and weaving, silk reeling was invented to answer the growing demands of the weaving industry. By analysing the relationship between silk utilisation and silkworm rearing, silkworm domestication was motivated and prompted by the growing demand from silk reeling workshops. Silk reeling appeared after the birth of weaving and before the activity of rearing silkworms. Combined with the scientific study results of the silkworm taming and domestication time, silk fibres were discovered and used before 7000 BP.

Amorphous germanium encapsulated in flexible nitrogen-doped carbon nanofiber for sodium storage with ultra-long cycling stability

Germanium (Ge), as a viable candidate anode material for future sodium-ion batteries, has attracted much attention. However, such material is usually troubled by huge volume changes during charge/discharge process, leading to the rapid degradation of electrochemical performance. Notably, construction of carbon coating layers is a practical strategy to alleviate the volumetric effect of Ge. Moreover, rational design of nanosized Ge with amorphous structure can also significantly enhance its sodium-ion storage performance. Herein, amorphous Ge (a-Ge) encapsulated by nitrogen-doped carbon nanofiber (Ge@NC) was successfully prepared by facile electrostatic spinning technique and annealing treatment. Impressively, the a-Ge nanoparticles are effectively protected by the flexible nitrogen-doped carbon nanofiber (NC), contributing to faster reaction kinetics and improved cycling stability since the high electrical conductivity and buffering effect of the NC layers. In addition, the nanosized Ge with amorphous structure can offer more open framework and higher structural stability. Therefore, the integrated Ge@NC electrode displays a high capacity of 404 mAh g−1 after 300 cycles at 0.1 A g−1. More excited, the synergistic effect of amorphous structure of Ge and nitrogen-doped carbon layers endow Ge@NC with remarkable long cycle life up to 15,000 cycles at 5 A g−1.

Comprehensive Study on Amino‐Modified Salix Wood Powder Membranes: Preparation, Adsorption Mechanism and Desorption Conditions for Efficient Chlortetracycline Removal

The wastewater of Chlortetracycline (CTC) poses a threat to the balance of aquatic ecosystems, promoting the formation and dissemination of antibiotic‐resistant bacterial strains in the aquatic environment. Moreover, such pollution can directly or indirectly affect human health through water sources, exacerbating the issue of antibiotic resistance. In response to this pollution challenge, Amino‐modified salix wood powder membrane(ASPPM) was prepared by phase transition and wet spinning techniques, aimed at removing CTC from water bodies. Adsorption experiment results show that the ASPPM maximum adsorption capacity for CTC is 458.99 mg/g. In the desorption process, the highest desorption rate of ASPPM for CTC was 79.65%. By fitting pseudo‐first‐order and pseudo‐second‐order kinetic models, it is found that the adsorption process of ASPPM on CTC is predominantly chemical adsorption. By fitting three isotherm models, it is found that the adsorption behavior of ASPPM on CTC is more in accordance with the Freundlich isotherm model, indicating multilayer adsorption on heterogeneous surfaces. The preparation of ASPPM study not only transforms renewable biomass materials into effective tools for environmental purification but also offers a cost‐effective new approach for sustainable environmental management, expanding the application of biomass materials in the field of environmental protection.

Synthesis and application of electrospun polyvinylidene fluoride/polyvinylidene glycol nanofibrous membrane for enhanced biomarker detection in immunochromatography assay

Immunochromatography assay (ICA) stands as a pioneering point-of-care testing (POCT) method, leveraging the simplicity, portability, and versatility of dry-strip testing method, chromatographic and antigen-antibody immunological reaction. Despite its numerous advantages, the shortcomings like low sensitivity, limited matrix, restricted matrix compatibility, and uncontrollable chromatographic rates, have hindered the ICA application. To overcome the aforementioned challenges, we proposed constructing a novel ICA strip based on homemade hydrophilic, flexible membranes to replace the commercially available nitrocellulose (NC). The key to the innovation lies in the spinning solution of a blend of poly (vinylidene fluoride) (PVDF) and polyethylene glycol (PEG), which is made into a nanofibrous membrane named EPVDF/PEG membrane by electrostatic spinning technique. This membrane, due to its high specific surface area and high porosity, can be loaded with more detection reagents than normal substrates, increasing the reaction time and achieving improved detection sensitivity. This membrane also has adjustable chromatographic rate, high protein loading capacity, good biocompatibility and excellent colouring ability. As a result, the established EPVDF/PEG-based ICA strips demonstrate an ultralow detection limit, as low as 0.5 mIU∙mL−1 when human chorionic gonadotropin (HCG) serves as the biomarker model, which is a 50-fold increase in detection sensitivity compared to commercial strips. Furthermore, EPVDF/PEG-based ICA strips can be produced on a large scale for the availability of efficient and mature electrospinning technologies. In summary, this work offers a transformative advancement in ICA development, potentially opening new horizons for sensitive biomarker detection.

Fast production of highly sensitive nanotextured nonwovens for detection of volatile amines, bacterial growth, and pH monitoring: New tools for real-time food quality monitoring

An efficient manufacturing of colorimetric nonwoven indicators represents a promising alternative to enable applications of such materials in food quality monitoring. The objective of this study is to use the solution blow spinning technique (SBS) to rapidly produce colorimetric nonwoven indicators based on polycaprolactone, incorporating natural or synthetic pH indicators to detect volatile amines, bacterial growth and monitor pH. Produced via the SBS method, these indicators were characterized aiming their physical, mechanical, thermal, and spectroscopic properties, evaluating their efficacy in detecting amines, monitoring bacterial growth, and pH, as well as assessing color stability during storage. The thermal stability and mechanical properties of the nonwovens practically always increased with the incorporation of natural and synthetic indicators. When exposed to volatile amines, the nonwoven indicators, particularly those embedded with bromophenol blue, displayed remarkable color change abilities in the presence of five volatile amines. These smart nonwovens in direct contact with E. coli K-12 or its volatiles in 24 h changed their color perceptible to the naked eye. The nanofiber nonwovens displayed visible color changes (ΔE ≥ 3) in response to buffer solutions (pH between 3 and 10). The smart nonwovens rapidly produced by the solution blow spinning method prove to be a promising tool for real-time monitoring of food freshness.

Composite of Hydrolyzed PAN and β-Cyclodextrin Forms a Nanofiber Membrane with an Excellent Removal Effect on Various Cationic Dyes and Copper Ions.

The presence of dyes and heavy metals in wastewater represents a significant environmental and public health hazard, necessitating the development of efficient materials for their removal. In this study, we modified hydrolyzed polyacrylonitrile (PAN-H) and combined it with β-cyclodextrin (β-CD) by using an electrostatic spinning technique to fabricate composite nanofibrous membranes for water treatment applications. The resulting PAN-H/β-CD nanofiber membranes exhibit spindle-shaped fibers and porous structures with a high density of charged functional groups, which significantly enhance their selective adsorption capacity compared to pure PAN fibers. Furthermore, post-treatment with a sodium bicarbonate solution further improved this capacity, resulting in the membranes demonstrating a remarkable adsorption efficiency for cationic dyes. The adsorption process conformed to the Langmuir and pseudo-second-order kinetic models, with maximum adsorption capacities of 216.94 mg/g for methylene blue (MB), 471.59 mg/g for malachite green (MG), 299 mg/g for crystal violet (CV), and 43.95 mg/g for copper ions. The selective adsorption of these positively charged contaminants, particularly cationic dyes and metallic copper, indicates that PAN-H/β-CD membranes have significant potential for the treatment of wastewater containing similar pollutants.

Highly Porous 3D Nanofibrous Scaffold of Polylactic Acid/Polyethylene Glycol/Calcium Phosphate for Bone Regeneration by a Two-Step Solution Blow Spinning (SBS) Facile Route.

This work presents the successful production of highly porous 3D nanofibrous hybrid scaffolds of polylactic acid (PLA)/polyethylene glycol (PEG) blends with the incorporation of calcium phosphate (CaP) bioceramics by a facile two-step process using the solution blow spinning (SBS) technique. CaP nanofibers were obtained at two calcium/phosphorus (Ca/P) ratios, 1.67 and 1.1, by SBS and calcination at 1000 °C. They were incorporated in PLA/PEG blends by SBS at 10 and 20 wt% to form 3D hybrid cotton-wool-like scaffolds. Morphological analysis showed that the fibrous scaffolds obtained had a randomly interconnected and highly porous structure. Also, the mean fiber diameter ranged from 408 ± 141 nm to 893 ± 496 nm. Apatite deposited considerably within 14 days in a simulated body fluid (SBF) test for hybrid scaffolds containing a mix of hydroxyapatite (HAp) and tri-calcium phosphate-β (β-TCP) phases. The scaffolds with 20 wt% CaP and a Ca/P ration of 1.1 showed better in vitro bioactivity to induce calcium mineralization for bone regeneration. Cellular tests evidenced that the developed scaffolds can support the osteogenic differentiation and proliferation of pre-osteoblastic MC3T3-E1 cells into mature osteoblasts. The results showed that the developed 3D scaffolds have potential applications for bone tissue engineering.

Multifunctional Analgesic Sutures from Microfluidic Spinning Technology.

Sutures are the most commonly used wound repair method after surgery. However, addressing delayed recovery and pain management remains a significant challenge. Here, microfibers are developed from microfluidic spinning with long-lasting analgesia capabilities for sutures. By using a solvent extraction manner, the polycaprolactone (PCL) microfibers encapsulated with ropivacaine (ROP), a well-known analgesic, can be continuously obtained from microfluidics. The intrinsic property of PCL and the advantage of microfluidic spinning technique impart the microfiber with highly controlled morphologies, mechanical strengths, as well as drug release. After exploring their biocompatibility both at in vitro and in vivo levels, the microfibers are directly applied to wound suture. The results demonstrate the lasting analgesic effect of the microfiber on mice with incision pain, highlighting its potential as promising suture for post-surgery treatments. It is anticipated that the multifunctional analgesic sutures produced through microfluidic spinning will pave the way for utilizing fibers as effective sutures in clinical incision wound treatment.

Efficient photocatalytic degradation of tetracycline and its derivatives by green recyclable PAN/Bi2WO6/Cu2O nanofiber membrane

The use of tetracycline antibiotics in industry, healthcare, animal husbandry, agriculture, and aquaculture has resulted in excessive concentrations in a variety of aquatic environments. In this work, PAN/Bi2WO6/Cu2O nanofibrous membranes (PBC ENMs) with photocatalytic degradation performance were successfully prepared using electrostatic spinning technique, and the morphology of catalysts and PBC ENMs were characterised by SEM, BET and UV–Vis. The results demonstrated that the prepared nanofibrous membranes could achieve 97.05 % photocatalytic degradation of TC under visible light, and the degradation efficiencies of its derivatives, chlortetracycline (CTC) and oxytetracycline (OTC), reached 90.87 % and 85.12 %, respectively. Free radical trapping experiments and mechanistic analyses showed that·O2– is the main active factor in the degradation process. The highest degradation rate of 97.05 % was achieved at initial pH = 7.2.PBC ENMs adsorbed above 87.5 % after six cycles of the experiment. The highest degradation rate of 97.05 % was achieved at initial pH = 7.2 PBC ENMs adsorbed above 87.5 % after six cycles of the experiment. Based on the above advantages, the preparation process of PBC ENMs is simple, low-cost and has good catalytic effect, which provides a simple and efficient treatment means for the treatment of TC wastewater and has a broad application prospect.

Enhanced energy storage capability of hydroxylated BiFeO3/PVDF composites designed by compositionally gradient multilayer structures

With the development of the microelectronics industry, there is a huge demand for flexible polymer dielectrics with excellent dielectric energy storage capacity, aimed at increasing dielectric constant and enhancing breakdown strength. In this study, the hydroxylated BiFeO3-loaded polyvinylidene fluoride(PVDF) composite films were prepared by electrostatic spinning techniques and the energy storage properties have been investigated. The results show that the dielectric constant and breakdown strength of the composites are effectively influenced by the hydroxylation modification and spatial structure. More interestingly, the seven-grade hydroxylated composite films exhibit a great enhancement of the excellent energy storage performances (Ue, ∼13.21 J/cm3; η, ∼66.2 %). This study demonstrates the immense potential of these composites as highly efficient dielectric materials suitable for use in energy storage capacitors.

Preparation and Study of PA6/CS Solution Blowing Antibacterial Nanofiber Membrane

Air pollution is becoming an increasingly pressing issue, with fiber-based air filtration materials now widely employed for personal protection, indoor purification and other purposes. However, conventional air filtration materials are only capable of filtering particles and the bacteria, viruses and other microorganisms that remain in the fires after filtration can be released under certain conditions, posing an additional risk to human health. Therefore, filter materials that incorporate antibacterial properties are better suited to meeting the needs of optimal human health. Nano-antimicrobial fibrous membranes with high filtration efficiency and low filtration resistance were prepared using polyamide 6 (PA6) and chitosan (CS) via solution blowing spinning technology. The membranes were shown to possess strong antimicrobial activity against both Gram-negative and Gram-positive bacteria. Additionally, they were found to effectively remove microbial contaminants from water. Technical abbreviations are explained upon first use. Ambiguity and biased language are avoided and the register remains formal throughout. The text has been proofread for grammatical and punctuation correctness. Performance tests were undertaken on the pre-fabricated fiber mesh and results indicated the CS/PA6 nanofiber mesh prepared by the solution blowing spinning technique had a complex three-dimensional structure, containing a significant number of cavity structures located between the fibers. The nanofiber mesh achieved a filtration efficiency of 99.92% against PM 0.3 with a pressure drop of 55 Pa in resistance and exhibited antibacterial performance of over 99.99% against Staphylococcus aureus. Addressing the limitations of traditional air filtration materials, including poor antibacterial effect, low efficiency, and high filtration resistance, is a practical consideration. Commercial opportunities arise in the areas of personal protection, indoor purification, and industrial filtration.

Architectural Design of a Multichannel Porous Carbon Fiber for Efficient Electromagnetic Microwave Absorption.

An ingenious microstructure of electromagnetic microwave absorption materials is crucial to achieve strong absorption and a broad bandwidth. Herein, one-dimensional (1D) carbon fibers with implantation of zero-dimensional (0D) ZIF-8-derived carbon frameworks and construction of a three-dimensional (3D) microcosmic multichannel porous structure are fabricated by electro-blown spinning, solvent-thermal reaction, and high-temperature pyrolysis techniques. The 1D carbon fiber skeleton with a multichannel structure provides a direct axial conductive pathway for charge transport, which plays an important role in dielectric loss. The 0D surface carbon frameworks offer plenty of heterogeneous interfaces to trigger intensive interfacial polarization loss and act as dihedral angles for microwave scattering. The 3D microcosmic multichannel pores can not only generate multiple reflections as much as possible to dissipate electromagnetic microwave energy but also supply huge interior cavities to improve impedance matching. Thanks to the synergistic effect of a strong electrically conductive pathway for enhancing the conductive loss, a plenteous heterogeneous interface for triggering intensive interfacial polarization loss, microcosmic multichannel pores for generating multiple reflections and improving impedance matching, and N and O atom doping for inducing dipole polarization, the optimal sample with an ingenious microstructure delivers an excellent absorption performance of a minimum reflection loss of -35.5 dB at a thickness of 5.0 mm and an effective absorption bandwidth of 6.72 GHz (10.96-17.68 GHz) at a thickness of 2.0 mm. Such a well-designed multichannel porous carbon fiber may pave the way for the exploitation of high-performance microwave absorbing materials.

Hierarchically Structured Cellulose Acetate@Silk Protein Membrane with Enhanced Mechanical and Electromagnetic Interference Shielding Performances.

Compared to conventional fibers, electrospun porous nanofibers with hierarchical structures often involve additional active sites, interfaces, and internal spaces which boost the performances of functional materials. Here in this study, coaxial composite cellulose acetate@silk fibroin (CA@SF) fibrous membranes are constructed through an electrostatic spinning technique combining solvent-induced phase separation. Hierarchical core-shell structures on the fibers are achieved, which significantly increases the surface area and benefits the mechanical property, flux, as well as the electroless deposition of Ag nanoparticles. The total electromagnetic shielding efficiency of the sandwiched hierarchical CA@SF@Ag composite membrane with a thickness of only 100 μm reaches up to 100 dB, surpassing around 82% beyond nonhierarchical ones. To be noticed, when post-treated by ethanol, the membrane enables an enhanced tensile strength of up to 10 MPa with a thickness of only 50 μm. Our findings pave the way to the application of electrospun fiber membranes in the field of ultrathin electromagnetic shielding films.

3D nanofiber sponge based on natural insect quaternized chitosan/pullulan/citric acid for accelerating wound healing

Extensive traumatic injuries and difficult-to-heal wounds, induced by many circumstances, impose a significant social and economic burden on an annual basis. Thus, innovative wound dressings that encourage wound healing are greatly needed. In this work, we prepared a novel insect chitosan (MCS) using waste pupal shells from housefly (Musca domestica L.) culture. After conducting comparative investigations with commercially available chitosan, it was shown that MCS exhibited comparable qualities and may be used as a substitute source of commercial chitosan. A quaternized chitosan/pullulan/citric acid three-dimensional nanofiber sponge (3D-NS) of natural origin was prepared by electrostatic spinning and gas foaming techniques after MCS was quaternized. In vitro, tests showed that the 3D-NS had a higher liquid absorption capacity than the two-dimensional nanofibrous membrane (2D-NM). Additionally, the 3D-NS showed improved hemostatic, pro-cell proliferation, antibacterial, and anti-inflammatory qualities. In vitro, tests demonstrated that 3D-NS could inhibit the release of inflammatory factors, promote angiogenesis, accelerate collagen deposition, and promote wound contraction. These effects considerably facilitated the healing process of wounds in rats with full-thickness skin damage. In conclusion, the great bioactivity and physicochemical properties of 3D-NS render it an optimal candidate for developing novel wound dressings.