Hemostasis Evaluation of Antibacterial and Highly Absorbent Composite Wound Dressings in Animal Hemostasis Models.

To reduce the bleeding time and to shorten the surgery time are vital to patients' prog-nosis, therefore, in this study, high moisture absorption nonwoven composites are proposed to attain hemostasis in time. Polyacrylate fiber and Tencel® fibers at different blending ratios (10:90, 20:80, 30:70, 40:60, and 50:50) are used to form PT composite nonwoven. Next, composed of a 50:50 ratio, PT composite nonwoven exhibits the maximal vertical wicking height of 4.4 cm along the cross direction. Additionally, the UV-Vis absorption spectra analysis shows that at absorption waves of 413-415 nm, the occurring of distinct peaks suggests the presence of nanoparticles. The XRD patterns indicate the presence of silver nanoparticles with corresponding crystal planes of characteristic peaks at (111), (200), and (220). Polyacrylate/Tencel® nonwoven composites exhibit comparable adsorption capacity of blood and water molecules. In particular, 30PT composite nonwoven outperforms the control group, exhibiting 3.8 times and 4.7 times greater the water absorption and blood absorption, respectively. Moreover, a great number of red blood cells with a size of 4-6 µm agglomerate among fibers as observed in SEM images, while 6hr-PT composite dressing demonstrates the optimal antibacterial efficacy against Escherichia coli and Staphylococcus aureus, proven by the zone of inhibition being 1.9 mm and 0.8 mm separately. When in contact with plasma, hemostasis composites have plasma hemostasis prothrombin time of 97.9%, and activated partial thromboplastin time of 96.7%. As for animal hemostasis model, the arteria over the rats' thigh bones is cut open perpendicularly, generating mass arteria hemorrhage. To attain hemostasis, it takes 46.5% shorter time when using composite dressings (experimental group) than the control group.

Functional Hollow Ceramic Microsphere/Flexible Polyurethane Foam Composites with a Cell Structure: Mechanical Property and Sound Absorptivity.

Noise pollution is the primary environmental issue that is increasingly deteriorated with the progress of modern industry and transportation; hence, the purpose of this study is to create flexible PU foam with mechanical properties and sound absorption. In this study, hollow ceramic microsphere (HCM) is used as the filler of polyurethane (PU) foam for mechanical reinforcement. The sound absorption efficacy of PU pores and the hollow attribute of HCM contribute to a synergistic sound absorption effect. HCM-filled PU foam is evaluated in terms of surface characteristic, mechanical properties, and sound absorption as related to the HCM content, determining the optimal functional flexible PU foam. The test results indicate that the presence of HCM strengthens the stability of the cell structure significantly. In addition, the synergistic effect can be proven by a 2.24 times greater mechanical strength and better sound absorption. Specifically, with more HCM, the flexible PU foam exhibits significantly improved sound absorption in high frequencies, suggesting that this study successfully generates functional PU foam with high mechanical properties and high sound absorption.

Preparation of Needleless Electrospinning Polyvinyl Alcohol/Water-Soluble Chitosan Nanofibrous Membranes: Antibacterial Property and Filter Efficiency.

Electrospinning is an efficient method of producing nanofibers out of polymers that shows a great potential for the filtration territory. Featuring water-soluble chitosan (WS-CS), a low-pollution process and a self-made needleless machine, PVA/WS-CS nanofibrous membranes were prepared and evaluated for nanofiber diameter, bacteriostatic property, filtration efficiency, pressure drop, and quality factor. Test results indicate that the minimal fiber diameter was 216.58 ± 58.15 nm. Regardless of the WS-CS concentration, all of the PVA/WS-CS nanofibrous membranes attained a high porosity and a high water vapor transmission rate (WVTR), with a pore size of 12.06-22.48 nm. Moreover, the membranes also exhibit bacteriostatic efficacy against Staphylococcus aureus, an optimal quality factor of 0.0825 Pa-1, and a filtration efficiency as high as 97.0%, that is 72.5% higher than that of common masks.

Lay-Up Compound Matrices for Application of Medical Protective Clothing: Manufacturing Techniques and Property Evaluations.

Medical protective clothing is the first line of defense for medical staff, which makes the acquisition of protection and multiple function challenging. When it comes to contagious diseases, the physical properties of protective clothing are deemed the top priority and, subsequently, they have significant meaning for the structural design, production cost evaluation, convenient production, and innovation. In this study, nonwoven technology is employed to produce matrices in which mechanical properties are supported by Tencel fibers and recycled Kevlar fibers. Next, the electrostatic spinning is conducted to generate breathable and waterproof films. The nonwoven fabrics and membranes are combined to have diverse functions, forming lay-up compound matrices for medical protective clothing. Moreover, measurements are conducted to characterize the lay-up compound matrices in terms of the tensile strength, tearing strength, bursting strength, puncture resistance, stiffness, air-permeable property, surface resistance, comfort performance, sub-micron particulate filtration efficiency, and the penetration of synthetic blood. As for the nonwoven fabrics, the mechanical properties are significantly improved after Kevlar fibers are incorporated. The tensile strength is (62.6 ± 2.4) N along the machine direction (MD) and (50.1 ± 3.1) N along the cross machine direction (CD); the tearing strength is (29.5 ± 1.6) N along the MD and (43.0 ± 1.7) N along the CD; the bursting strength is (365.8 ± 5.0) kPa; and the puncture resistance is (22.6 ± 1.0) N. Moreover, the lay-up compound matrices exhibit a stiffness of (14.7 ± 0.2) cm along the MD and (14.6 ± 0.1) cm along the CD, a surface resistance of (2.85 × 109 ± 0.37 × 109) Ω, an air-permeable property of (45.4 ± 2.3) cm3/s/cm2, and sub-micron particulate filtration efficiency of over 98%. In the measurement for penetration of synthetic blood, the K40/PAN/TPU group prevents the synthetic blood from penetration. Hence, the incorporation of recycled Kevlar fibers and lay-up compound technique creates good physical properties, an appropriate comfort attribute, and functions, which suggests that this study provides a greater diversity and new concepts for the production of medical protective clothing.

A Study on Carbon Fiber Composites with Low-Melting-Point Polyester Nonwoven Fabric Reinforcement: A Highly Effective Electromagnetic Wave Shield Textile Material.

In this study, a low-melting-point polyester nonwoven fabric (L), a nylon spacer fabric (N), and a carbon fiber woven fabric (C) are laminated in different orders and then needle-bonded at a depth of 15.0 cm to form NLC, NLN, CLC, and CLN composites with a sandwich construction. Regardless of the lamination order, four composite types exhibit high tensile strengths and tearing strengths. Based on the ASTM D4935-18 test standard, the electromagnetic wave shielding measurement is conducted in a frequency range of 1~3 GHz. The two groups-NLC and CLN-demonstrate different electromagnetic wave shields, which are -45~-65 dB for the former, and -60 dB for the latter. According to FTTS-FA-003, in the specified requirements of the test method for electromagnetic shielding textiles, the proposed composites achieve level III, which is the highest standard, and are thus qualified for use in the aviation, construction, and commerce fields.

Evaluations of Electrostatic Filtration Efficiency and Antibacterial Efficacy of Antibacterial Electret Polypropylene Filters: Effects of Using Low Molecular Antibacterial Agent as Additive.

In recent years, air filtration has been gaining much attention, and now people are much more concerned about antibacterial filters due to the spreading of COVID-19. The electret polypropylene (PP) nonwoven fabrics possess excellent filtration efficiency but a limited antibacterial effect against S. aureus and E. coli, and therefore triclosan is used in this study. Serving as an antibacterial agent, triclosan with a low molecular weight is an effective additive for the test results, indicating that the presence of triclosan strengthens the antibacterial effects of the filters. In addition, triclosan also strengthens the PP's crystallinity, which in turn betters the filtration efficiency of the filters concurrently. Demonstrating powerful filtration and antibacterial performances, the antibacterial electret PP filters are highly qualified for filter applications.

Evaluation of Repellent Effectiveness of Polyvinyl Alcohol/Eucalyptus globules Nanofibrous Membranes against Forcipomyia taiwana.

This study aims to develop nanofibrous membranes where Eucalyptus globules oil (EGO) is wrapped in polyvinyl alcohol (PVA). The EGO-based nanofibrous membranes are then evaluated for the protection against Forcipomyia taiwana (F. taiwana). In the first stage, the PVA solutions are formulated with different concentrations and are measured for viscosity and electrical conductivity. In the next stage, PVA solution and EGO are blended at different ratios and electrospun into PVA/EGO nanofibrous membranes (i.e., EGO-based repellent). In this study, a PVA concentration of 14 wt% has a positive influence on fiber formation. Furthermore, the finest nanofibers of 291 nm are presented when the voltage is 15 kV. The repellent efficacy can reach 80% in a 60-min release when the repellent is composed of a PVA/oil ratio of 90/10. To sum up, the nanofibrous membranes of essential oil exhibit good repellent efficacy against F. taiwana and significant slow-release effect, instead of adversely affecting the cell viability.

Influence of magnetic domain walls and magnetic field on the thermal conductivity of magnetic nanowires.

We investigated the influence of magnetic domain walls and magnetic fields on the thermal conductivity of suspended magnetic nanowires. The thermal conductivity of the nanowires was obtained using steady-state Joule heating to measure the change in resistance caused by spontaneous heating. The results showed that the thermal conductivity coefficients of straight and wavy magnetic nanowires decreased with an increase in the magnetic domain wall number, implying that the scattering between magnons and domain walls hindered the heat transport process. In addition, we proved that the magnetic field considerably reduced the thermal conductivity of a magnetic nanowire. The influence of magnetic domain walls and magnetic fields on the thermal conductivity of polycrystalline magnetic nanowires can be attributed to the scattering of long-wavelength spin waves mediated by intergrain exchange coupling.

Compare analysis for the nanotoxicity effects of different amounts of endocytic iron oxide nanoparticles at single cell level.

Developing methods that evaluate the cellular uptake of magnetic nanoparticles (MNPs) and nanotoxicity effects at single-cellular level are needed. In this study, magnetophoresis combining fluorescence based cytotoxicity assay was proposed to assess the viability and the single-cellular MNPs uptake simultaneously. Malignant cells (SKHep-1, HepG2, HeLa) were incubated with 10 nm anionic iron oxide nanoparticles. Prussian blue stain was performed to visualize the distribution of magnetic nanoparticles. MTT and fluorescence based assay analyzed the cytotoxicity effects of the bulk cell population and single cell, respectively. DAPI/PI stained was applied to evaluate death mechanism. The number of intracellular MNPs was found to be strongly correlated with the cell death. Significant differences between cellular MNP uptake in living and dead cells were observed. The method could be useful for future study of the nanotoxicity induced by MNPs.

Wheatstone bridge giant-magnetoresistance based cell counter.

A Wheatstone bridge giant magnetoresistance (GMR) biosensor was proposed here for the detection and counting of magnetic cells. The biosensor was made of a top-pinned spin-valve layer structure, and it was integrated with a microchannel possessing the function of hydrodynamic focusing that allowed the cells to flow in series one by one and ensured the accuracy of detection. Through measuring the magnetoresistance variation caused by the stray field of the magnetic cells that flowed through the microchannel above the GMR biosensor, we can not only detect and count the cells but we can also recognize cells with different magnetic moments. In addition, a magnetic field gradient was applied for the separation of different cells into different channels.

Single cell detection using 3D magnetic rolled-up structures.

A 3D rolled-up structure made of a SiO2 layer and a fishbone-like magnetic thin film was proposed here as a biosensor. The magnetoresistance (MR) measurement results of the sensor suggest that the presence of the stray field, which is induced by the magnetic nanoparticles, significantly increased the switching field. Comparing the performance of the 2D sensor and 3D sensor designed in this study, the response in switching field variation was 12.14% in the 2D sensor and 62.55% in the 3D sensor. The response in MR ratio variation was 4.55% in the 2D sensor and 82.32% in the 3D sensor. In addition, the design of the 3D sensor structure also helped to attract and trap a single magnetic cell due to its stronger stray field compared with the 2D structure. The 3D magnetic biosensor designed here can provide important information for future biochip research and applications.

Magnetically-controllable zigzag structures as cell microgripper.

We designed and fabricated a micro-scaled cell gripper based on two highly flexible magnetic zigzag structures that can be actuated by a magnetic field. Elongated single domain magnetic thin films with high magnetic shape anisotropy were deposited on the zigzag structures. By adjusting the external magnetic field we were able to control the torque applied on the magnetic films that was responsible for the actuation. We measured and discussed the displacement of the zigzag structures under different magnetic fields, and we observed a hysteresis characteristic in the actuation. Furthermore, we demonstrated the ability of gripping a single cell in water solution using the designed cell microgripper. The cell microgripper proposed in this study can provide important information for future biochip and biomedical applications.

Application of the laser Doppler flowmeter for measurement of blood pressure and functional parameters of microcirculation.

The laser Doppler flowmeter has become an effective tool for the clinical study of microcirculation with non-invasive measurements and excellent velocity resolution. Microcirculation flow measurements cannot be used as reference criteria for circulation function. Thus, the relative change in fingertip microcirculation was measured through inflation and deflation of an automatic sphygmomanometer wrapped around the arm, and the blood pressure and functional parameters of circulation, such as biological zero (BZ), peak flow (PF) and time to peak flow (tp), were determined. For 50 healthy participants, the correlation coefficients for the laser Doppler flowmeter and oscillometric results were 0.950 and 0.838 for systolic and diastolic pressure, respectively. The mean and standard errors for both methods fell within the range specified in the Association for the Advancement of Medical Instrumentation standards. The BZ of an edema patient was about 5 times higher than normal. For patients with peripheral arterial occlusive disease (PAOD), the PF could not be determined, and the tp was about twice the normal value. The accuracy of blood pressure measurements using the laser Doppler flowmeter was comparable to that of the commonly used oscillometric sphygmomanometer, and the physiological circulation functional parameters were useful in identifying signs of edema and PAOD.

Electrowetting on dielectric driven droplet resonance and mixing enhancement in parallel-plate configuration.

This study experimentally verifies that the mixing process in a droplet can be enhanced by driving the droplet at resonant frequencies and at alternating driving frequencies using a parallel-plate electrowetting on dielectric device. The mixing time, which is defined as the time required for reaching the well-mixed state, in a resonant droplet is found to be significantly shorter than that in a non-resonant droplet. Besides, it is also found that a higher driving potential leads to a better mixing effect, especially at resonant frequencies. Furthermore, when a droplet is driven by alternating two driving frequencies, especially two resonant frequencies, the mixing efficiency is found to be significantly enhanced for a specific alternating duration of these two frequencies.