Fabrication of Poly(Lactic Acid)@TiO2 Electrospun Membrane Decorated with Metal-Organic Frameworks for Efficient Air Filtration and Bacteriostasis.

The development of high-performance filtration materials is essential for the effective removal of airborne particles, and metal-organic frameworks (MOFs) anchored to organic polymer matrices are considered to be one of the most promising porous adsorbents for air pollutants. Nowadays, most air filters are generally based on synthetic fiber polymers derived from petroleum residues and have limited functionality, so the use of MOFs in combination with nanofiber air filters has received a lot of attention. Here, a conjugated electrostatic spinning method is demonstrated for the one-step preparation of poly(lactic acid) (PLA) nanofibrous membranes with a bimodal diameter distribution and the anchoring of Zeolitic Imidazolate Framework-8 (ZIF-8) by the introduction of TiO2 and in situ generation to construct favorable multiscale fibers and rough structures. The prepared PLA/TZ maintained a good PM2.5 capture efficiency of 99.97%, a filtration efficiency of 96.43% for PM0.3, and a pressure drop of 96.0 Pa, with the highest quality factor being 0.08449 Pa-1. Additionally, ZIF-8 was uniformly generated on the surface of PLA and TiO2 nanofibers, obtaining a roughened structure and a larger specific surface area. An enhanced filtration retention effect and electrostatic interactions, as well as active free radicals, can be generated for the deep inactivation of bacteria. Compared with the unmodified membrane, PLA/TZ prepared antibacterial characteristics induced by photocatalysis and Zn2+ release, with excellent bactericidal effects against S. aureus and E. coli. Overall, this work may provide a promising approach for the development of efficient biomass-based filtration materials with antimicrobial properties.

Bicomponent core/sheath melt-blown fibers for air filtration with ultra-low resistance.

With the escalating air pollution and frequent outbreaks of airborne diseases, there is a growing demand for personal protective filtration media. Melt-blown nonwovens have proven to be highly effective in capturing tiny particles, but their tightly packed fiber assemblages are more resistant to airflow and less comfortable to breathe. Here, we present a one-step melt-blown spinning process for the production of bicomponent core/sheath (BCS) crimped fibers and their application in high-efficiency, low-resistance air filtration. Fiber curl is caused by unbalanced internal stresses resulting from differences in the structure components, resulting in uneven shrinkage inside and outside the fibers. The resulting CM@S-2 filtration media features a uniform fiber curl and a porous fiber mesh structure, which reduces air filtration resistance. Under the same filtration conditions, the filtration efficiency of CM@S-2 (96.58% vs. 95.58%), filtration resistance (56.1 Pa vs. 108.0 Pa), quality factor (0.061 Pa-1vs. 0.029 Pa-1), and dust holding capacity (10.60 g m-2vs. 9.10 g m-2) were comparable to those of the single-component polypropylene filters. The filtration efficiency of the CM@S-2 remained above 94.0% after 30 days of indoor storage. Computational Fluid Dynamics (CFD) simulation demonstrated that crimped fibers effectively reduce pressure surges on the filter media caused by fiber accumulation. In comparative tests with commercial masks, the CM@S-2 cartridge masks demonstrated superior air permeability compared to commercial masks under similar filtration conditions. In conclusion, the bicomponent core/sheath melt-blown fibers significantly reduce air resistance and show excellent potential for application in protective masks.

Preparation of fluffy bimodal conjugated electrospun poly(lactic acid) air filters with low pressure drop.

Electrospun nanofiber membranes have been extensively studied as air filters. However, their limited filtration efficiency for submicron inhalable particulate matter (PM), high resistance to filtration, and limited capacity to hold dust have hindered their widespread use. The majority of materials come from petroleum, and the use of organic solvents during the spinning process has a significant negative impact on the environment. In this work, a sustainable method has been proposed for producing filters using poly(lactic acid) (PLA) with a bimodal diameter distribution through conjugated electrospinning. This technique allows for the continuous production of interconnected micro/nano hybrid porous membranes, resulting in reduced resistance and improved dust holding capacity. The filtration efficiency, pressure drop, long-term filtration performance, and actual performance of the conjugated bimodal membrane (CBM) were extensively investigated. The results indicate that the filter has a high capacity for retaining particles, with filtration efficiencies of 99.94% for PM 0.3 and 99.96% for PM 2.5. It also demonstrates a high quality factor (0.078 Pa-1 for PM 0.3 and 0.084 Pa-1 for PM 2.5), long-term stability (a decrease of 2.35% for PM 0.3 and 0.05% for PM 2.5 over a period of 60 days) and outstanding dust holding capacity (9.17 g m-2). The conjugated bimodal membrane (CBM) shows a 22.64% decrease in resistance compared to the non-conjugated bimodal membrane (BM). In general, the approach outlined in this work provides valuable insights into the development of high-performance biodegradable air filters. These filters have improved filtration efficiency and reduced resistance.

Preparation of Self-Curling Melt-Blown Fibers with Crimped Masterbatch (CM) and Its Application for Low-Pressure Air Filtration.

Particulate matter (PM) and airborne viruses pose significant threats to both the environment and public health. As the most viable solution to prevent the inhalation of these pollutants, there is an urgent demand for face masks with excellent filtration efficiency and low-pressure drop. In this study, a crimped masterbatch (CM) is added to polypropylene feedstocks to produce curling fibers through melt-blown spinning. These curled fibers exhibit low filtration resistance and effective dust-holding performances when used for air filtration. The effect of adding CM on fiber diameter, pore size, crimp, porosity, roughness, and surface potential was studied. The filtration performance of the materials, including the PM filtration capabilities, recirculation filtration, and loading test performance, were also investigated. The results demonstrate that the degree of fiber crimp can be adjusted by incorporating varying amounts of CM. This curling was caused by the uneven shrinkage that occurred due to variations in thermal contraction between these polymers. The curled fibers created a fluffy structure in the fiber network and modified the distribution of pore sizes within it. Under the same filtration conditions as sodium chloride aerogel, CM-2 (PP:CM 8:2) exhibited similar filtration efficiency (95.54% vs. 94.74%), lower filtration resistance (88.68 Pa vs. 108.88 Pa), higher quality factor (0.035 Pa-1 vs. 0.028 Pa-1) and better dust holding capacity (10.39 g/m2 vs. 9.20 g/m2) compared to CM-0 (PP:CM 10:0). After 30 days of indoor storage, the filtration efficiency of CM-2 remained above 94%. The self-curling melt-blown filtration material developed here could potentially be applied in the field of protective masks.

Never in mitosis gene A-related kinase-6 deficiency deteriorates diabetic cardiomyopathy via regulating heat shock protein 72.

NIMA (never in mitosis, gene A)-related kinase-6 (NEK6), a cell cycle regulatory gene, was found to regulate cardiac hypertrophy. However, its role in diabetes-induced cardiomyopathy has not been fully elucidated. This research was designed to illustrate the effect of NEK6 involved in diabetic cardiomyopathy. Here we used a streptozotocin (STZ)-induced mice diabetic cardiomyopathy model and NEK6 knockout mice to explore the role and mechanism of NEK6 in diabetic-induced cardiomyopathy. NEK6 knockout mice and wild-type littermates were subjected to STZ injection (50 mg/kg/day for 5 days) to induce a diabetic cardiomyopathy model. As a result, 4 months after final STZ injection, DCM mice revealed cardiac hypertrophy, fibrosis, and systolic and diastolic dysfunction. NEK6 deficiency causes deteriorated cardiac hypertrophy, fibrosis, and cardiac dysfunction. Furthermore, we observed inflammation and oxidative stress in the hearts of NEK6 deficiency mice under diabetic cardiomyopathy pathology. Adenovirus was used to upregulate NEK6 in neonatal rat cardiomyocytes, and it was found that NEK6 ameliorated high glucose-induced inflammation and oxidative stress. Our findings revealed that NEK6 increased the phosphorylation of heat shock protein 72 (HSP72) and increased the protein level of PGC-1α and NRF2. Co-IP assay experiment confirmed that NEK6 interacted with HSP72. When HSP72 was silenced, the anti-inflammation and anti-oxidative stress effects of NEK6 were blurred. In summary, NEK6 may protect diabetic-induced cardiomyopathy by interacting with HSP72 and promoting the HSP72/PGC-1α/NRF2 signaling. KEY MESSAGES: NEK6 knockout deteriorated cardiac dysfunction, cardiac hypertrophy, fibrosis as well as inflammation response, and oxidative stress. NEK6 overexpression attenuated high glucose induced inflammation and oxidative stress. The underlying mechanisms of the protective role of NEK6 in the development of diabetic cardiomyopathy seem to involve the regulation of HSP72-NRF2- PGC-1α pathway. NEK6 may become a new therapeutic target for diabetic cardiomyopathy.

Fabrication of Laminated Micro/Nano Filter and Its Application for Inhalable PM Removal.

Particulate matter (PM) with a diameter of 0.3 µm is inhalable and brings great threats to human health. Traditional meltblown nonwovens used for air filtration need to be treated by high voltage corona charging, which has the problem of electrostatic dissipation and thus reduces the filtration efficiency. In this work, a kind of composite air-filter with high efficiency and low resistance was fabricated by alternating lamination of ultrathin electronspun nano-layer and melt-blown layer without corona charging treatment. The effects of fiber diameter, pore size, porosity, layer number, and weight on filtration performance were investigated. Meanwhile, the surface hydrophobicity, loading capacity, and storage stability of the composite filter were studied. The results indicate that the filters (18.5 gsm) laminated by 10 layers fiber-webs present excellent filtration efficiency (97.94%), low pressure drop (53.2 Pa), high quality factor (QF 0.073 Pa-1), and high dust holding capacity (9.72 g/m2) for NaCl aerosol particles. Increasing the layers and reducing individual layer weight can significantly improve filtration efficiency and reduce pressure drop of the filter. The filtration efficiency decayed slightly from 97.94% to 96.48% after 80 days storage. The alternate arrangement of ultra-thin nano and melt-blown layers constructed a layer-by-layer interception and collaborative filtering effect in the composite filter, realizing the high filtration efficiency and low resistance without high voltage corona charging. These results provided new insights for the application of nonwoven fabrics in air filtration.

Structural Polymorphism of Guanine Quadruplex-Containing Regions in Human Promoters.

Intramolecular guanine quadruplexes (G4s) are non-canonical nucleic acid structures formed by four guanine (G)-rich tracts that assemble into a core of stacked planar tetrads. G4-forming DNA sequences are enriched in gene promoters and are implicated in the control of gene expression. Most G4-forming DNA contains more G residues than can simultaneously be incorporated into the core resulting in a variety of different possible G4 structures. Although this kind of structural polymorphism is well recognized in the literature, there remain unanswered questions regarding possible connections between G4 polymorphism and biological function. Here we report a detailed bioinformatic survey of G4 polymorphism in human gene promoter regions. Our analysis is based on identifying G4-containing regions (G4CRs), which we define as stretches of DNA in which every residue can form part of a G4. We found that G4CRs with higher degrees of polymorphism are more tightly clustered near transcription sites and tend to contain G4s with shorter loops and bulges. Furthermore, we found that G4CRs with well-characterized biological functions tended to be longer and more polymorphic than genome-wide averages. These results represent new evidence linking G4 polymorphism to biological function and provide new criteria for identifying biologically relevant G4-forming regions from genomic data.

Highly stable lithium anodes from recycled hemp textile.

Three-dimensional lithium (Li) hosts have been shown to suppress the growth of Li dendrites for next generation Li metal batteries. Here, we report a cost-effective and scalable approach to produce highly stable Li composite anodes from industrial hemp textile waste. The hemp@Li composite anodes demonstrate stable cycling both in half and full cells.