为制备具有抗菌性能的空气过滤材料,以聚砜(PSF)为溶质、N,N-二甲基甲酰胺(DMF)和 1-甲基-2-吡咯烷酮(NMP)为溶剂,先采用静电纺丝法制备PSF纳米纤维膜,然后在其表面磁控溅射氧化锌(ZnO)薄膜,最后通过水热合成法将 ZnO 薄膜转化为沸石咪唑酯骨架-8(ZIF8)晶体,得到PSF/ZIF8 纳米纤维膜,并对该复合膜的物化性能、过滤性能、透气性能、抗菌与细菌过滤性能进行测试.结果表明:PSF/ZIF8 纳米纤维膜对PM0.3 的过滤效率可达到 99.82%.纳米纤维膜的高孔隙率使其表现出较高的透气率(340.36 mm·s-1).此外,该复合膜对金黄色葡萄球菌和大肠杆菌均有一定的抗菌性能,且对 2 种菌的拦截效率均达到 99.99%.

Objective Air filter material is the most commonly used and effective medium to deal with air pollution as well as ultraviolet radiation, especially to block the transmission of pathogens in the air. In addition, the bacteria intercepted during use are loaded on the surface of the filter material, which is easy to cause secondary pollution. In order to deal with air pollution and ultraviolet radiation and acquire antibacterial function at the same time, this paper focuses on the preparation of an air filter material with antibacterial and ultraviolet protective properties. Method PS/PVDF nanofibrous membranes were prepared by electrospinning using polystyrene（PS） and polyvinylidene fluoride（PVDF） as the main raw materials. The optimal volume ratio of PS and PVDF spinning solutions was determined by analyzing the micromorphology, mechanical properties and air permeability of the fibrous membranes with different mixing ratios. Silver（Ag） and zinc（Zn） nanocoatings were sputtered on both sides of the selected nanofibrous membrane, respectively. The micromorphology, element composition, pore size distribution, air permeability, filtration, ultraviolet（UV） protection and antibacterial properties of the PS/PVDF/Ag/Zn composite membrane were studied.Results When the volume ratio of PS to PVDF is 1：2, the fibrous membrane has high breaking stress（2.31 MPa） and good air permeability（177.2 mm/s）, which meet the requirements of the practical application. On this basis, PS/PVDF fibrous membrane with a surface density of 2.88 g/m~2 and a volume ratio of 1：2 was prepared. The surface of the fibrous membrane was modified with different sputtering time periods to prepare PS/PVDF/Ag/Zn fibrous membrane. The Ag and Zn metal particles sputtered on the fibrous membrane surface achieve uniform deposition（Fig.4）, and the combination stability between them and the fibrous membrane is excellent（Fig.6）. After performance characterization, it was found that when the sputtering time was 8 min, compared with the PS/PVDF fibrous membrane without sputtering, the pore diameter of PS/PVDF/Ag/Zn fibrous membrane was 7.76 μm reduced to 6.36 μm, air permeability decreases slightly（Fig.7）, the filtration efficiency of 300 nm NaCl aerosol particles was increased to 99.7%, the pressure drop slightly increased to 103 Pa, and the quality factor value increased to 0.056 Pa -1 （Fig.8）. Compared with the PS/PVDF fibrous membrane without sputtering, when the sputtering time was 8 min, the ultraviolet protection factor（UPF） of PS/PVDF/Ag/Zn membrane reaches 702.52±55.15, and the transmittance of long wave ultraviolet（UVA） and short wave ultraviolet（UVB） was（0.26±0.01）% and（0.20±0.02）%, respectively, showing excellent UV protection performance. The PS/PVDF fibrous membrane without sputtering did not demonstrate antibacterial effect, while the width of the inhibition zone of the PS/PVDF/Ag/Zn membrane with sputtering time period of 8 min against Escherichia coli and Staphylococcus aureus reached 3.5 mm and 6.2 mm, respectively, which can effectively reduce the growth of bacteria and prolong the service life of the filter material in practical applications.Conclusion PS/PVDF fibrous membrane was prepared by electrospinning, and Ag and Zn nanocoatings were deposited on both sides of the fibrous membrane by magnetron sputtering. The results show that the metal coating on the fibrous membrane surface roughens the fibrous surface, reduces the pore size, and improves the filtration efficiency of the fibrous membrane. The presence of Zn and Ag also endows the fibrous membrane with UV protection and antibacterial properties. An air filter material with antibacterial and UV protective properties has been successfully prepared. This research provides a new idea for the research and development of functional air filter materials.

A multi-use fibrous filter medium composed of an electrospun polyimide (PI) nanofiber layer and a functional zeolitic imidazolate framework-8 (ZIF8) nanofilm layer was successfully fabricated to cope with the complex environmental pollution issues. The nanofilm layer consists of the anti-microbial ZIF8 converted from non-toxic zinc oxide (ZnO) nanocoating on PI fibers. One-step magnetron sputtering is utilized to deposit the ZnO nano coating for the sake of desired functionality conformally onto the PI nanofibrous membrane without sacrificing its bulk structure and mechanical performance. The as-prepared PI/ZIF8 nanofibrous filter medium showed conspicuous biocidal efficacy and excellent interception ratio against gram-negative Escherichia coli (>99.9%) and gram-positive Staphylococcus aureus (>99.9%) within 20 min contact. Besides, compared with commercial media, the bilayer PI/ZIF8 fibrous medium showed exceptional thermal-wet comfortability due to the high porosity that could realize effective heat and humidity conduction. Moreover, the PI/ZIF8(30) NFM still present a high filtration efficiency of 99.6% towards PM0.3 even after treated at 300 degree celsius for 1 h. Furthermore, the PI/ZIF8(30) NFM with a fiber basis weight of 1.8 g/m(2) was endowed with a permeate flux of 17,279.2 L/m(2)/h and a high oil/ water separation efficiency of > 99.6% because of the hydrophobicity and superoleophilicity. We envision that the antimicrobial, thermal-wet comfort, multi-use fibrous membrane will serve as a core-medium of environmentally-friendly platform for bioprotective equipment against future pathogen threats or oily wastewater treatment.

Personal protective mask (PPM) is becoming an effective and convenient apparatus to protect people from harmful air contaminant caused by air pollution and highly infectious respiratory disease. Most of the available PPM can barely possess high capture efficiency towards particulate matters (PMs) and antibacterial activity. Herein, an environmentally friendly and bilayer structured fabric with timely bactericidal efficacy was fabricated through the recombination of silver/zinc two-sides sputtered cotton (SAg/ZnC) and polylactic acid/polycaprolactone (PLA/PCL) composite nanofibers (CNF). A hydroelectricity stimulation was touched off inside the CNF@SAg/ZnC fabric profiting from the external water vapor and then the fabric was given antimicrobial function. The resulting CNF@SAg/ZnC fabric possess intriguing characters, such as high filtration efficiency towards PM0.3 (> 99%) with the airflow rate fixed at 85 L/min(-1), good antibacterial activity, favorable cell viability, excellent bactericidal ratio against Escherichia coli (99.33%) and Staphylococcus aureus (99.19%) when contact with bacteria for 20 min, and long-lasting durability (> 12 h). This work is solely up to the requirements of biodegradable and high-performance media for public health protection, making it a good choice of multifunctional personal protective equipment.

为促进三维纤维空气过滤材料的发展,针对现有二维纳米纤维滤材堆积结构不可控、容尘量小和稳定性差等问题,通过分析国内外相关文献,系统介绍了纳米纤维基气凝胶的基本特点、制备方法和功能修饰,归纳总结了现阶段天然高聚物和合成高聚物两大类纳米纤维基气凝胶在空气过滤领域的应用研究,阐述了纳米纤维基气凝胶可作为过滤器核心介质的优势,分析了气凝胶结构和聚合物功能化技术对过滤材料综合性能的影响.指出当前纳米纤维基气凝胶滤材在实际应用中面临的问题,提出应重点提高材料的过滤性能和循环使用性,强化对不同空气污染物的过滤或吸附能力等.

Face mask has become an essential and effective apparatus to protect human beings from air pollution, especially the air-borne pathogens. However, most commercial face masks can hardly achieve good particulate matters (PMs) and high bactericidal efficacy concurrently. Herein, a bilayer structured composite filter medium with built-in antimicrobial activities was constructed by combining cotton woven modified by magnetron sputtered Ag/Zn coatings and electrospun poly(vinylidene fluoride)/polystyrene (PVDF/PS) nanofibers. With the benefit of external moisture, an electrical stimulation was generated inside the composite fabric and thus endowed the fabric antimicrobial function. The resultant composite fabric presented conspicuous performance for integrated air pollution control, high filtration performance towards PM0.3 (99.1%, 79.2 Pa) and exceptional interception ratio against Escherichia coli (99.64%) and Staphylococcus aureus (98.75%) within 20 min contact. The high efficiency contact sterilization function of the bilayer fabric could further potentially promote disinfection and reuse of the filter media. This work may provide a new perspective on designing high-performance face mask media for public health protection.

综述耐高温静电纺纤维膜材料的制备及功能化研究情况.分别介绍了聚砜类、聚酰亚胺类、芳香族聚酰胺类等有机纤维和氧化铝、二氧化钛、氧化锆、二氧化硅等无机纤维静电纺过滤膜材料的过滤性能及功能改性研究进展,重点分析了聚合物功能化技术、纺丝液组成、后处理工艺等对静电纺纤维膜过滤材料综合性能的影响.指出在实际应用中耐高温有机纤维过滤材料机械性能、阻燃性能还需改进,无机纤维过滤材料较脆,容易变形破损,容尘量需提升.认为:静电纺纤维膜耐高温空气过滤材料在功能改性、容尘量、可重复使用性等方面还需深入研究,实现批量化生产.

The water vapor exhaled by the human body can severely accelerate the charge dissipation of commercial face masks, thereby reducing the electrostatic adsorption efficiency and increasing the bacterial invasion risk. This study developed an electroactive antibacterial cotton nonwoven (Ag/cotton/Zn) using eco-friendly magnetron sputtering technology. The Ag/Zn electrode constructed on the surface of cotton nonwovens could produce a microelectric field in the moist environment of human respiration, which endowed Ag/cotton/Zn with excellent electroactivity. When Ag/cotton/Zn was used as an additional layer of polypropylene melt-blown nonwovens or polylactic acid nanofibers, the prepared personal protective air filter had a filtration efficiency of up to 96.8% and an appropriate pressure drop and air permeability. The antibacterial results based on bacterial aerosols showed that the antibacterial efficiency against Escherichia coli and Staphylococcus aureus in 20 min was 99.74 and 99.79%, respectively, indicating an excellent electroactive killing efficiency against airborne bacteria. In addition, Ag/cotton/Zn showed excellent biological security. These results shed some light on the design and fabrication of next generation of personal protective air filter materials driven by human breathing.

OBJECTIVE:To explore the different influences of walking, running and stair activity on knee articular cartilage with T1 rho and T2 mapping sequences.MATERIALS AND METHODS:MRI (3.0-T) scans of the right knee were performed in twenty-three young healthy adults immediately after 30 minutes of rest, walking, running and stair activity respectively. Articular cartilage was quantitatively assessed based on T1 rho and T2 relaxation times. Analysis of variance for random block design data, bonferroni test and paired samples t tests were performed to estimate the different influences of physiological activities on articular cartilage.RESULTS:T1 rho and T2 values had reductions after physiological activities in all regions of articular cartilage. T1 rho and T2 values were decreased more after running than walking. T1 rho and T2 values were decreased more after stair activity than running, except for femoral cartilage. The superficial layer of patella cartilage had higher reduction rates than the deep layer. The T1 rho and T2 values of articular cartilage were reduced in the following order: patellofemoral cartilage> medial tibiofemoral cartilage> lateral tibiofemoral cartilage. Patellofemoral cartilage experienced reductions in the following order: lateral part> middle part> medial part. Tibiofemoral cartilage had reductions in the following order: posterior part> middle part> anterior part.CONCLUSIONS:T1 rho and T2 mapping sequences can quantitatively reflect the different influences of physiological activities on knee articular cartilage. Fluid shifts, collagen fiber deformation, spatial heterogeneity, inherent differences in material properties and tissue stiffness have close relationship with cartilage loading characteristics.

Osteoarthritis (OA) is a serious problem in the recent aging society, and early diagnosis and intervention of articular cartilage degeneration are very important for the onset of OA. Therefore, development of newer MRI techniques is necessary and expected for detection of early articular cartilage degeneration.