Bio-inspired gradient poly(lactic acid) nanofibers for active capturing of PM0.3 and real-time respiratory monitoring.

The concept of bio-inspired gradient hierarchies, in which the well-defined MOF nanocrystals serve as active nanodielectrics to create electroactive shell at poly(lactic acid) (PLA) nanofibers, is introduced to promote the surface activity and electroactivity of PLA nanofibrous membranes (NFMs). The strategy enabled significant refinement of PLA nanofibers during coaxial electrospinning (∼40 % decline of fiber diameter), accompanied by remarkable increase of specific surface area (nearly 1.5 m2/g), porosity (approximately 85 %) and dielectric constants for the bio-inspired gradient PLA (BG-PLA) NFMs. It largely boosted initial electret properties and electrostatic adsorption capability of BG-PLA NFMs, as well as charge regeneration by TENG mechanisms even under high-humidity environment. The BG-PLA NFMs thus featured exceptionally high PM0.3 filtration efficiencies with well-controlled air resistance (94.3 %, 163.4 Pa, 85 L/min), in contrast to the relatively low efficiency of only 80.0 % for normal PLA. During the application evaluation of outdoor air purification, excellent long-term filtering performance was demonstrated for the BG-PLA for up to 4 h (nearly 98.0 %, 53 Pa), whereas normal PLA exhibited a gradually declined filtration efficiency and an increased pressure drop. Moreover, the BG-PLA NFMs of increased electroactivity were ready to generate tribo-output currents as driven by respiratory vibrations, which enabled real-time monitoring of electrophysiological signals. This bio-inspired gradient strategy opens up promising pathways to engender biodegradable nanofibers of high surface activity and electroactivity, which has significant implications for intelligent protective membranes.

A "twelve-section ultrasonic screening and diagnosis method" and management system for screening and treating neonatal congenital heart disease at the grassroots level in Tang County, Hebei Province, China.

BACKGROUND: To explore a method for screening and diagnosing neonatal congenital heart disease (CHD) applicable to grassroots level, evaluate the prevalence of CHD, and establish a hierarchical management system for CHD screening and treatment at the grassroots level. METHODS: A total of 24,253 newborns born in Tang County between January 2016 and December 2020 were consecutively enrolled and screened by trained primary physicians via the "twelve-section ultrasonic screening and diagnosis method" (referred to as the "twelve-section method"). Specialized staff from the CHD Screening and Diagnosis Center of Hebei Children's Hospital regularly visited the local area for definite diagnosis of CHD in newborns who screened positive. Newborns with CHD were managed according to the hierarchical management system. RESULTS: The centre confirmed that, except for 2 newborns with patent ductus arteriosus missed in the diagnosis of ventricular septal defect combined with severe pulmonary hypertension, newborns with other isolated or concomitant simple CHDs were identified at the grassroots level. The sensitivity, specificity and diagnostic coincidence rate of the twelve-section method for screening complex CHD were 92%, 99.6% and 84%, respectively. A total of 301 children with CHD were identified. The overall CHD prevalence was 12.4‰. According to the hierarchical management system, 113 patients with simple CHD recovered spontaneously during local follow-up, 48 patients continued local follow-up, 106 patients were referred to the centre for surgery (including 17 patients with severe CHD and 89 patients with progressive CHD), 1 patient died without surgery, and 8 patients were lost to follow-up. Eighteen patients with complex CHD were directly referred to the centre for surgery, 3 patients died without surgery, and 4 patients were lost to follow-up. Most patients who received early intervention achieved satisfactory results. The mortality rate of CHD was approximately 28.86 per 100,000 children. CONCLUSIONS: The "twelve-section method" is suitable for screening neonatal CHD at the grassroots level. The establishment of a hierarchical management system for CHD screening and treatment is conducive to the scientific management of CHD, which has important clinical and social significance for early detection, early intervention, reduction in mortality and improvement of the prognosis of complex and severe CHDs.

TATA-binding associated factors have distinct roles during early mammalian development.

Early embryonic development is a finely orchestrated process that requires precise regulation of gene expression coordinated with morphogenetic events. TATA-box binding protein-associated factors (TAFs), integral components of transcription initiation coactivators like TFIID and SAGA, play a crucial role in this intricate process. Here we show that disruptions in TAF5, TAF12 and TAF13 individually lead to embryonic lethality in the mouse, resulting in overlapping yet distinct phenotypes. Taf5 and Taf12 mutant embryos exhibited a failure to implant post-blastocyst formation, and Taf5 mutants have aberrant lineage specification within the inner cell mass. In contrast, Taf13 mutant embryos successfully implant and form egg-cylinder stages but fail to initiate gastrulation. Strikingly, we observed a depletion of pluripotency factors in TAF13-deficient embryos, including OCT4, NANOG and SOX2, highlighting an indispensable role of TAF13 in maintaining pluripotency. Transcriptomic analysis revealed distinct gene targets affected by the loss of TAF5, TAF12 and TAF13. Thus, we propose that TAF5, TAF12 and TAF13 convey locus specificity to the TFIID complex throughout the mouse genome.

An RRM domain protein SOE suppresses transgene silencing in rice.

Gene expression is regulated at multiple levels, including RNA processing and DNA methylation/demethylation. How these regulations are controlled remains unclear. Here, through analysis of a suppressor for the OsEIN2 over-expressor, we identified an RNA recognition motif protein SUPPRESSOR OF EIN2 (SOE). SOE is localized in nuclear speckles and interacts with several components of the spliceosome. We find SOE associates with hundreds of targets and directly binds to a DNA glycosylase gene DNG701 pre-mRNA for efficient splicing and stabilization, allowing for subsequent DNG701-mediated DNA demethylation of the transgene promoter for proper gene expression. The V81M substitution in the suppressor mutant protein mSOE impaired its protein stability and binding activity to DNG701 pre-mRNA, leading to transgene silencing. SOE mutation enhances grain size and yield. Haplotype analysis in c. 3000 rice accessions reveals that the haplotype 1 (Hap 1) promoter is associated with high 1000-grain weight, and most of the japonica accessions, but not indica ones, have the Hap 1 elite allele. Our study discovers a novel mechanism for the regulation of gene expression and provides an elite allele for the promotion of yield potentials in rice.

Room-Temperature Smart Sensor Based on Indium Acetate-Functionalized Perovskite CsPbBr3 Nanocrystals for Monitoring Electrolyte in Lithium-Ion Batteries.

Monitoring electrolyte components is an effective means of determining the safety status of lithium-ion batteries. In this study, indium acetate was taken as a ligand to functionalize perovskite CsPbBr3 nanocrystals, and then the room-temperature electrolyte sensor based on CsPbBr3 nanocrystals with ligand indium acetate was prepared. The sensor offers high response, long-term stability (21 days), and low detection limits for ethyl methyl carbonate (10 ppm), diethyl carbonate (10 ppm), and ethyl butyrate (1 ppm) gases at room temperature and boasts a fast response/recovery time (1500 ppm, 58.27/103.82 s, 33.58/40.62 s, and 45.05/103.08 s, respectively). Density functional theory results show that the gas sensitivity comes from the adsorption of an electrolyte, which changes the density-of-state distribution so that the electrical response curve changes. And using computational fluid dynamics simulation, it was found that the time required for gas detection by the built-in sensor (3.1 s) was 8.7 times shorter than that of the implantable sensor. This work provides inspiration and rationale for embedding and integrating room-temperature sensors into lithium-ion batteries to monitor safety and health conditions.

Exosome complex components 1 and 2 are vital for early mammalian development.

Exosome Complex Components 1 and 2 (EXOSC1 and 2) are two proteins in the RNA Exosome complex whose main function is 5' → 3' RNA degradation and processing. The RNA exosome complex is comprised of nine subunits that form two separate components: the S1/KH cap and the PH-core. EXOSC1 and 2 are both part of the S1/KH cap and are involved in binding nascent RNA. As part of a systemic characterization of early lethal alleles produced by the Knockout Mouse Project, we have examined Exosc1 and Exosc2 homozygous null (mutant) embryos to determine developmental and molecular phenotypes of embryos lacking their functions. Our studies reveal that Exosc1 null embryos implant and form an egg cylinder but are developmentally delayed and fail to initiate gastrulation by embryonic day 7.5. In contrast, Exosc2 null embryos are lethal during peri-implantation stages, and while they do form a morphologically normal blastocyst at E3.5, they cannot be recovered at post-implantation stages. We show the absence of stage-specific developmental and altered lineage-specification in both Exosc1 and Exosc2 mutant embryos and conclude that these genes are essential for the successful progression through early mammalian development.

Experimental study on the purification capacity of potted plants on low-concentration carbon monoxide in indoor environment.

Indoor low-concentration carbon monoxide (CO) exposure is widespread worldwide, and potted plants may be a potential means for CO purification. The objective is to evaluate common indoor plants' CO purification and tolerance capacities. Epipremnum aureum (Linden ex André) G.S.Bunting, Chlorophytum comosum (Thunb.) Jacques, Spathiphyllum kochii Engl. & K.Krause, and Sansevieria trifasciata Hort. ex Prain with similar sizes were tested in the glass chamber with initial CO concentrations of 10, 25, 50, 100, 200, and 400 ppm, respectively. (1) The CO purification capacity of the four potted plants is ranked as Epipremnum aureum (Linden ex André) G.S.Bunting > Chlorophytum comosum (Thunb.) Jacques > Spathiphyllum kochii Engl. & K.Krause > Sansevieria trifasciata Hort. ex Prain. Under the purification effect of each plant, the CO concentration in the chamber decreases linearly and significantly (p < 0.05), and within a specific time period, the time-weighted average (TWA) CO concentrations can be reduced to below the corresponding permissible exposure limits specified by some countries and organizations. (2) With the increase of the stomatal number of each plant and the increase in CO concentration, the hourly and cumulative absorbed CO of each plant increase linearly and significantly (p < 0.05). (3) With the increase in CO concentration, the CO purification efficiency of each plant decreases exponentially and significantly (p < 0.05). (4) When the CO concentration was ≤ 50 ppm, all plants could effectively purify CO without damage. When the CO concentration was in the range of 100 ~ 400 ppm, within 2 weeks after the 48-h experiment, the leaf tips of Chlorophytum comosum (Thunb.) Jacques and Epipremnum aureum (Linden ex André) G.S.Bunting were damaged one after another, and the damaged leaf area increased with the increase of CO concentration. However, each plant as a whole still survived. This study demonstrated that different species of potted plants can effectively absorb low concentrations of CO to varying degrees, but higher concentrations of CO will damage the survival of specific species of potted plants.

Nanopatterned Electroactive Polylactic Acid Nanofibrous MOFilters for Efficient PM0.3 Filtration and Bacterial Inhibition.

Biodegradable polylactic acid (PLA) nanofibrous membranes (NFMs) hold great potential to address the increasing airborne particulate matter (PM) and dramatic accumulation of plastic/microplastic pollution. However, the field of PLA NFM-based filters is still in its infancy, frequently dwarfed by the bottlenecks regarding relatively low surface activity, poor electroactivity, and insufficient PM capturing mechanisms. This effort discloses a microwave-assisted approach to minute-level synthesis of dielectric ZIF-8 nanocrystals with high specific surface area (over 1012 m2/g) and ultrasmall size (∼240 nm), which were intimately anchored onto PLA nanofibers (PLA@ZIF-8) by a combined "electrospinning-electrospray" strategy. This endowed the PLA@ZIF-8 NFMs with largely increased electroactivity in terms of elevated dielectric coefficient (an increase of 202%), surface potential (up to 5.8 kV), and triboelectric properties (output voltage of 30.8 V at 10 N, 0.5 Hz). Given the profound control over morphology and electroactivity, the PLA@ZIF-8 NFMs exhibited efficient filtration of PM0.3 (97.1%, 85 L/min) with a decreased air resistance (592.5 Pa), surpassing that of the pure PLA counterpart (88.4%, 650.9 Pa). This was essentially ascribed to realization of multiple filtration mechanisms for PLA@ZIF-8 NFMs, including enhanced physical interception, polar interactions, and electrostatic adsorption, and the unique self-charging function triggered by airflow vibrations. Moreover, perfect antibacterial performance was achieved for PLA@ZIF-8, showing ultrahigh inhibition rates of 99.9 and 100% against E. coli and S. aureus, respectively. The proposed hierarchical structuring strategy, offering the multifunction integration unattainable with conventional methods, may facilitate the development of biodegradable long-term air filters.

Dual roles of the Arabidopsis PEAT complex in histone H2A deubiquitination and H4K5 acetylation.

Histone H2A monoubiquitination is associated with transcriptional repression and needs to be removed by deubiquitinases to facilitate gene transcription in eukaryotes. However, the deubiquitinase responsible for genome-wide H2A deubiquitination in plants has yet to be identified. In this study, we found that the previously identified PWWP-EPCR-ARID-TRB (PEAT) complex components interact with both the ubiquitin-specific protease UBP5 and the redundant histone acetyltransferases HAM1 and HAM2 (HAM1/2) to form a larger version of PEAT complex in Arabidopsis thaliana. UBP5 functions as an H2A deubiquitinase in a nucleosome substrate-dependent manner in vitro and mediates H2A deubiquitination at the whole-genome level in vivo. HAM1/2 are shared subunits of the PEAT complex and the conserved NuA4 histone acetyltransferase complex, and are responsible for histone H4K5 acetylation. Within the PEAT complex, the PWWP components (PWWP1, PWWP2, and PWWP3) directly interact with UBP5 and are necessary for UBP5-mediated H2A deubiquitination, while the EPCR components (EPCR1 and EPCR2) directly interact with HAM1/2 and are required for HAM1/2-mediated H4K5 acetylation. Collectively, our study not only identifies dual roles of the PEAT complex in H2A deubiquitination and H4K5 acetylation but also illustrates how these processes collaborate at the whole-genome level to regulate the transcription and development in plants.

8-hour performance of loose-fitting powered air-purifying respirators in simulated hospital and coal mine environments.

Loose-fitting powered air-purifying respirators (LF-PAPRs) are increasingly used in hospitals and coal mines because of their high comfort and protection level, but the utilization faces the challenges of 8-hr continuous high protection requirements in the hospital environment and the coupling effects of high temperature, high humidity, high dust concentration in coal mines. Based on the self-developed powered air-purifying respirator simulation test system, this study explores the 8-hr changes of supplied airflow, the relative air pressure inside the inlet covering (ΔP), and total inward leakage (TIL) of four models of LF-PAPRs in simulated hospital and coal mine environments. Results show that: (1) In a simulated hospital environment, all four LF-PAPRs showed filter cartridge blockage within 5 ∼ 6 hr of continuous operation; while in the simulated coal mine, three models of LF-PAPRs showed filter cartridge blockage within 3 hr. (2) In both the hospital and coal mine environments, there are cases where the supplied airflow of LF-PAPRs dropped below 170 L/min within 3 hr. (3) In a simulated hospital environment, the ΔP of all LF-PAPRs maintained positive within 5-6 hr; while in the simulated coal mine, the ΔP of two LF-PAPRs, respectively, appeared negative after 1 hr and 1.6 hr operation. (4) The maximum TIL of the tested LF-PAPRs, respectively ranged from 0.5-0.9% and 1.4-3% in simulated hospital and coal mine environments. (5) In both hospital and coal mine environments, the supplied airflow and ΔP of each LF-PAPR showed a decreasing trend with increasing test duration, while the TIL significantly increased with testing time. (6) The supplied airflow, ΔP, and TIL of each LF-PAPR in the simulated hospital environment performed better than those in the coal mine. This study evaluated the performance of PAPR under the most severe operating conditions, and respirator performance may differ under in-situ conditions.

DDM1-mediated R-loop resolution and H2A.Z exclusion facilitates heterochromatin formation in Arabidopsis.

Programmed constitutive heterochromatin silencing is essential for eukaryotic genome regulation, yet the initial step of this process is ambiguous. A large proportion of R-loops (RNA:DNA hybrids) had been unexpectedly identified within Arabidopsis pericentromeric heterochromatin with unknown functions. Through a genome-wide R-loop profiling screen, we find that DDM1 (decrease in DNA methylation 1) is the primary restrictor of pericentromeric R-loops via its RNA:DNA helicase activity. Low levels of pericentromeric R-loops resolved by DDM1 cotranscriptionally can facilitate constitutive heterochromatin silencing. Furthermore, we demonstrate that DDM1 physically excludes histone H2A variant H2A.Z and promotes H2A.W deposition for faithful heterochromatin initiation soon after R-loop clearance. The dual functions of DDM1 in R-loop resolution and H2A.Z eviction are essential for sperm nuclei structure maintenance in mature pollen. Our work unravels the cotranscriptional R-loop resolution coupled with accurate H2A variants deposition is the primary step of constitutive heterochromatin silencing in Arabidopsis, which might be conserved across eukaryotes.

WRKY transcription factors and OBERON histone-binding proteins form complexes to balance plant growth and stress tolerance.

WRKY transcription factors in plants are known to be able to mediate either transcriptional activation or repression, but the mechanism regulating their transcriptional activity is largely unclear. We found that group IId WRKY transcription factors interact with OBERON (OBE) proteins, forming redundant WRKY-OBE complexes in Arabidopsis thaliana. The coiled-coil domain of WRKY transcription factors binds to OBE proteins and is responsible for target gene selection and transcriptional repression. The PHD finger of OBE proteins binds to both histones and WRKY transcription factors. WRKY-OBE complexes repress the transcription of numerous stress-responsive genes and are required for maintaining normal plant growth. Several WRKY and OBE mutants show reduced plant size and increased drought tolerance, accompanied by increased expression of stress-responsive genes. Moreover, expression levels of most of these WRKY and OBE genes are reduced in response to drought stress, revealing a previously uncharacterized regulatory mechanism of the drought stress response. These results suggest that WRKY-OBE complexes repress transcription of stress-responsive genes, and thereby balance plant growth and stress tolerance.

Bioelectret poly(lactic acid) membranes with simultaneously enhanced physical interception and electrostatic adsorption of airborne PM0.3.

Traditional polymeric fibrous membranes have been extensively used to reduce the health risks caused by airborne particulate matter (PM), leading to the dramatically increasing pollution of plastics and microplastics. Although great efforts have been made to develop poly(lactic acid) (PLA)-based membrane filters, they are frequently dwarfed by their relatively poor electret properties and electrostatic adsorptive mechanisms. To resolve this dilemma, a bioelectret approach was proposed in this work, strategically involving the bioinspired adhesion of dielectric hydroxyapatite nanowhiskers as a biodegradable electret to promote the polarization properties of PLA microfibrous membranes. In addition to significant improvements in tensile properties, the incorporation of hydroxyapatite bioelectret (HABE) enabled remarkable increase in the removal efficiencies of ultrafine PM0.3 in a high-voltage electrostatic field (10 and 25 kV). This was exemplified by the largely increased filtering performance (69.75%, 23.1 Pa) for PLA membranes loaded with 10 wt% HABE at the normal airflow rate (32 L/min) compared to the pristine PLA counterpart (32.89%, 7.2 Pa). Although the filtration efficiency of PM0.3 for the counterpart dramatically decreased to 21.6% at 85 L/min, the increment was maintained at nearly 196% for the bioelectret PLA, while an ultralow pressure drop (74.5 Pa) and high humidity resistance (RH 80%) were achieved. The unusual property combination were ascribed to the HABE-enabled realization of multiple filtration mechanisms, including the simultaneous enhancement of physical interception and electrostatic adsorption. The significant filtration applications, unattainable with conventional electret membranes, demonstrate the bioelectret PLA as a promising biodegradable platform that allows high filtration properties and humidity resistance.

Biodegradable Electroactive Nanofibrous Air Filters for Long-Term Respiratory Healthcare and Self-Powered Monitoring.

The concept of triboelectric nanogenerator (TENG)-based fibrous air filters, in which the electroactive fibers are ready to enhance the electrostatic adsorption by sustainable energy harvesting, is appealing for long-term respiratory protection and in vivo real-time monitoring. This effort discloses a self-reinforcing electroactivity strategy to confer extreme alignment and refinement of the electrospun poly(lactic acid) (PLA) nanofibers, significantly facilitating formation of electroactive phases (i.e., ß-phase and highly aligned chains and dipoles) and promotion of polarization and electret properties. It endowed the PLA nanofibrous membranes (NFMs) with largely increased surface potential and filtration performance, as exemplified by efficient removal of PM0.3 and PM2.5 (90.68 and 99.82%, respectively) even at the highest airflow capacity of 85 L/min. With high electroactivity and a well-controlled morphology, the PLA NFMs exhibited superior TENG properties triggered by regular respiratory vibrations, enabling 9.21-fold increase of surface potential (-1.43 kV) and nearly 68% increase of PM0.3 capturing (94.3%) compared to those of conventional PLA membranes. The remarkable TENG mechanisms were examined to elaborately monitor the personal respiration characteristics, particularly those triggered large and rapid variations of output voltages like coughing and tachypnea. Featuring desirable biocompatibility and degradability, the self-powered PLA NFMs permit promising applications in the fabrication of ecofriendly air filters toward high-performance purification and intelligent monitoring.

Electroactive, Antibacterial, and Biodegradable Poly(lactic acid) Nanofibrous Air Filters for Healthcare.

Poly(lactic acid) (PLA)-based nanofibrous membranes (NFMs) hold great potential in the field of biodegradable filters for air purification but are largely limited by the relatively low electret properties and high susceptibility to bacteria. Herein, we disclosed a facile approach to the fabrication of electroactive and antibacterial PLA NFMs impregnated with a highly dielectric photocatalyst. In particular, the microwave-assisted doping (MAD) protocol was employed to yield Zn-doped titanium dioxide (Zn-TIO), featuring the well-defined anatase phase, a uniform size of ∼65 nm, and decreased band gap (3.0 eV). The incorporation of Zn-TIO (2, 6, and 10 wt %) into PLA gave rise to a significant refinement of the electrospun nanofibers, decreasing from the highest diameter of 581 nm for pure PLA to the lowest value of 264 nm. More importantly, dramatical improvements in the dielectric constants, surface potential, and electret properties were simultaneously achieved for the composite NFMs, as exemplified by a nearly 94% increase in surface potential for 3-day-aged PLA/Zn-TIO (90/10) compared with that of pure PLA. The well regulation of morphological features and promotion of electroactivity contributed to a distinct increase in the air filtration performance, as demonstrated by 98.7% filtration of PM0.3 with the highest quality factor of 0.032 Pa-1 at the airflow velocity of 32 L/min for PLA/Zn-TIO (94/6), largely surpassing pure PLA (89.4%, 0.011 Pa-1). Benefiting from the effective generation of reactive radicals and gradual release of Zn2+ by Zn-TIO, the electroactive PLA NFMs were ready to profoundly inactivate Escherichia coli and Staphylococcus epidermidis. The exceptional combination of remarkable electret properties and excellent antibacterial performance makes the PLA membrane filters promising for healthcare.

Kaposiform hemangioendothelioma of the heart: a case report and literature review.

Kaposiform hemangioendothelioma is a rare tumour of vascular origin that rarely occurs in the heart. We provided a rare case of a 26-day-old infant with tachypnoea. Echocardiography showed a solid tumour in the pericardial cavity and a large amount of pericardial effusion. The solid tumour was confirmed by surgery, and the pathology was kaposiform hemangioendothelioma. We analysed this case and reviewed the related literature to explore the clinical features and echocardiographic manifestations to improve the understanding, diagnosis, and treatment of this disease for clinicians and sonographers.

Biodegradable MOFilters for Effective Air Filtration and Sterilization by Coupling MOF Functionalization and Mechanical Polarization of Fibrous Poly(lactic acid).

High-performance air filtration materials are important for addressing the airborne pollutants. Herein, we propose an unprecedented access to biodegradable poly(lactic acid) (PLA)-based MOFilters with excellent filtering performance and antibacterial activity. The fabrication involved a stepwise in situ growth of zeolitic imidazolate framework-8 (ZIF-8) crystals at the surface of microfibrous PLA membranes, followed by mechanical polarization under high pressure and low temperature (5 MPa, 40 °C) to trigger the ordered alignment of dipoles in PLA chains and ZIF-8. The unique structural features allowed these PLA-based MOFilters to achieve an exceptional combination of excellent tensile properties, high dielectric constant (up to 2.4 F/m), and enhanced surface potential as high as 4 kV. Arising from the remarkable surface activity and electrostatic adsorption effect, a significant increase (from over 12% to nearly 20%) in PM0.3 filtration efficiency was observed for the PLA-based MOFilters compared to that of pure PLA counterparts, with weak relation to the airflow velocities (10-85 L/min). Moreover, the air resistance was controlled at a considerably low level for all the MOFilters, that is, below 183 Pa even at 85 L/min. It is worth noting that distinct antibacterial properties were achieved for the MOFilters, as illustrated by the inhibitive rates of 87 and 100% against Escherichia coli and Staphylococcus aureus, respectively. The proposed concept of PLA-based MOFilters offers unprecedented multifunction integration, which may fuel the development of biodegradable versatile filters with high capturing and antibacterial performances yet desirable manufacturing feasibility.

Bioelectrets in Electrospun Bimodal Poly(lactic acid) Fibers: Realization of Multiple Mechanisms for Efficient and Long-Term Filtration of Fine PMs.

Despite the great potential in fabrication of biodegradable and eco-friendly air filters by electrospinning poly(lactic acid) (PLA) membranes, the filtering performance is frequently dwarfed by inadequate physical sieving or electrostatic adsorption mechanisms to capture airborne particulate matters (PMs). Here, using the parallel spinning approach, the unique micro/nanoscale architecture was established by conjugation of neighboring PLA nanofibers, creating bimodal fibers in electrospun PLA membranes for the enhanced slip effect to significantly reduce the air resistance. Moreover, the bone-like nanocrystalline hydroxyapatite bioelectret (HABE) was exploited to enhance the dielectric and polarization properties of electrospun PLA, accompanied by the controlled generation of junctions induced by the microaggregation of HABE (10-30 wt %). The incorporated HABE was supposed to orderly align in the applied E-field and largely promote the charging capability and surface potential, gradually increasing to 7.2 kV from the lowest level of 2.5 kV for pure PLA. This was mainly attributed to HABE-induced orientation of PLA backbone chains and C═O dipoles, as well as the interfacial charges trapped at the interphases of HABE-PLA and crystalline region-amorphous PLA. Given the multiple capturing mechanisms, the micro/nanostructured PLA/HABE membranes were characterized by excellent and sustainable filtering performance, e.g., the filtration efficiency of PM0.3 was promoted from 59.38% for pure PLA to 94.38% after addition of 30 wt % HABE at a moderate airflow capacity of 32 L/min and from 30.78 to 83.75% at the highest level of 85 L/min. It is of interest that the pressure drop was significantly decreased, mainly arising from the slip effect between the ultrafine nanofibers and conjugated microfibers. The proposed combination of the nanostructured electret and the multistructuring strategy offers the function integration of efficient filtration and low resistance that are highly useful to pursue fully biodegradable filters.