The hidden inequality: the disparities in the quality of daily use masks associated with family economic status

Wearing high-quality masks plays a critical role in reducing COVID-19 transmission. However, no study has investigated socioeconomic inequality in the quality of masks. Addressing this gap, this paper explored the relationships between mask’s quality and family economic status. The cross-sectional survey was conducted in two Chinese universities by distributing structured questionnaires to assess participants’ characteristics including family economic status, and meanwhile collecting their masks to evaluate the quality by measuring particle filtration efficiency. The valid responses were obtained from 912 students with mean age of 19.556 ± 1.453  years and were analyzed by using fractional or binary logistic regression. Three main findings were presented. First, inequality existed in the quality of masks. 36.07% of students were using unqualified masks with average filtration efficiency of 0.795 ± 0.119, which was much lower than China’s national standard (0.9). Of those masks with identified production date, 11.43% were manufactured during COVID-19 outbreak when market was flooded with counterfeit production, and thus were of poor quality with average filtration efficiency of 0.819 ± 0.152. Second, better family economic status was associated with better masks’ filtration efficiency and greater probability of using qualified masks. Third, students with better family economic status tend to use masks with individual packaging, and unique patterns and special designs, which may lead to inequality on a psychological level. Our analysis reveals the hidden socioeconomic inequality that exist behind cheap masks. In facing the challenges of future emerging infectious diseases, it is important to address the inequity to ensure equal access to affordable qualified personal protection equipment

Research on a Sliding Mode Vector Control System Based on Collaborative Optimization of an Axial Flux Permanent Magnet Synchronous Motor for an Electric Vehicle

In this paper, a sliding mode vector control system based on collaborative optimization of an axial flux permanent magnet synchronous motor (AFPMSM) for an electric vehicle is proposed. In order to increase the high efficiency range of electric vehicles and improve the cruising range, a collaborative optimization control strategy is firstly proposed. Due to the use of a dual stator-single rotor AFPMSM, the multi-motor efficiency optimization map and torque cooperative control are used to realize the working mode conversion of single stator and double stator, and the torque ripple caused by the working mode conversion is improved by fuzzy control. In order to improve the torque tracking capability, speed limiting characteristics, and operating characteristics, a speed limit and current vector control strategy based on a sliding mode controller is proposed and studied. The dynamic performance of electric vehicles is improved by a sliding mode vector control. Finally, a drive control system was developed for the proposed control strategy, and the complete vehicle test was carried out. The collaborative optimization control experiment and torque tracking and speed limiting experiments verify the correctness and effectiveness of the proposed control strategy. The acceleration performance and endurance experiments show that the proposed control strategy can effectively improve the cruising range and the acceleration performance of electric vehicles

Study on Topology and Control Strategy of High-Precision and Wide-Range Hybrid Converter for Photovoltaic Cell Simulator

Aiming at the function and technical requirements of high-power photovoltaic cell simulation, high-performance programmable logic power supply and dc motor simulation, a high frequency isolation hybrid topology and control strategy based on current-source/voltage-source converter was studied and proposed. Firstly, according to the performance requirements of photovoltaic cell analog power supply, the control strategy requirements of the high-precision wide-range hybrid topology were proposed. Secondly, the working principle of the new hybrid topology was analyzed. At the same time, the equivalent model of the new hybrid topology was simplified and established, and the overall control strategy of the hybrid topology based on current compensation and sliding mode variable structure was proposed. Finally, simulation and experimental research on the hybrid topology was carried out, and the experimental test of photovoltaic cell simulation was completed. The simulation and experimental results show that the hybrid topology and control strategy proposed in this paper has the characteristics of wide-range output regulation, fast dynamic response, high efficiency and high power factor, and can be used for high performance photovoltaic cell simulation, programmable logic power supply and DC motor simulation

Study on the Electromagnetic Design and Analysis of Axial Flux Permanent Magnet Synchronous Motors for Electric Vehicles

In order to provide a complete solution for designing and analyzing the axial flux permanent magnet synchronous motor (AFPMSM) for electric vehicles, this paper covers the electromagnetic design and multi-physics analysis technology of AFPMSM in depth. Firstly, an electromagnetic evaluation method based on an analytical algorithm for efficient evaluation of AFPMSM was studied. The simulation results were compared with the 3D electromagnetic field simulation results to verify the correctness of the analytical algorithm. Secondly, the stator core was used to open the auxiliary slot to optimize the torque ripple of the AFPMSM, which reduced the torque ripple peak-to-peak value by 2%. From the perspective of ensuring the reliability, safety, and driving comfort of the traction motor in-vehicle working conditions, multi-physics analysis software was used to analyze and check the vibration and noise characteristics and temperature rise of several key operating conditions of the automotive AFPMSM. The analysis results showed that the motor designed in this paper can operate reliably

Effect of Ordinary Portland Cement on Mechanical Properties and Microstructures of Metakaolin-Based Geopolymers

Geopolymers have been considered a sustainable alternative to ordinary Portland cement (CEM I) for its lower embodied carbon and ability to make use of industrial by-products. Additionally, its excellent engineering properties of high strength, low permeability, good chemical resistance, and excellent fire resistance also strike a chord in the minds of researchers. The goal of this study is to clarify the effect of calcium sources on the mechanical properties and microstructures of the geopolymers. CEM I was chosen as the sole calcium source, while metakaolin was used as the source material. Five distinct geopolymers were prepared, having various ratio of CEM I: 0%, 5%, 10%, 20%, and 30%. The alkali-activator was a mixture of 12 M sodium hydroxide (NaOH) and sodium silicate (Na2SiO3), utilizing compressive strength and flexural strength to evaluate the changes of the geopolymers’ mechanical properties. SEM, XRD, and FTIR were used to examine microscopic features, evaluate internal morphology, and analyze changes in components of the geopolymers containing different amounts of CEM I. The experimental results indicated that the optimal incorporation of CEM I was 5%. Under this dosage, the compressive strength and flexural strength of the geopolymers can reach 71.1 MPa and 6.75 MPa, respectively. With the incorporation of CEM I, the heat released by cement hydration can accelerate the geopolymerization reaction between silica-alumina materials and alkaline solutions. Additionally, the coexistence of N-A-S-H gel from components of an aluminosilicate mix and C-S-H gel from the CEM I promoted a more densified microstructure of the geopolymers and improved the geopolymer’s strength. However, as the amount of CEM I in the mixture increased, the geopolymer matrix was unable to provide enough water for the CEM I to hydrate, which prevented excessive CEM I from forming hydration products, weakening the workability of the matrix and eventually hindering the development of geopolymer strength

Resistance to Sulfuric Acid Corrosion of Geopolymer Concrete Based on Different Binding Materials and Alkali Concentrations

Geopolymer binder is expected to be an optimum alternative to Portland cement due to its excellent engineering properties of high strength, acid corrosion resistance, low permeability, good chemical resistance, and excellent fire resistance. To study the sulfuric acid corrosion resistance of geopolymer concrete (GPC) with different binding materials and concentrations of sodium hydroxide solution (NaOH), metakaolin, high-calcium fly ash, and low-calcium fly ash were chosen as binding materials of GPC for the geopolymerization process. A mixture of sodium silicate solution (Na2SiO3) and NaOH solution with different concentrations (8 M and 12 M) was selected as the alkaline activator with a ratio (Na2SiO3/NaOH) of 1.5. GPC specimens were immersed in the sulfuric acid solution with the pH value of 1 for 6 days and then naturally dried for 1 day until 98 days. The macroscopic properties of GPC were characterized by visual appearance, compressive strength, mass loss, and neutralization depth. The materials were characterized by SEM, XRD, and FTIR. The results indicated that at the immersion time of 28 d, the compressive strength of two types of fly ash-based GPC increased to some extent due to the presence of gypsum, but this phenomenon was not observed in metakaolin-based GPC. After 98 d of immersion, the residual strength of fly ash based GPC was still higher, which reached more than 25 MPa, while the metakaolin-based GPC failed. Furthermore, due to the rigid 3D networks of aluminosilicate in fly ash-based GPC, the mass of all GPC decreased slightly during the immersion period, and then tended to be stable in the later period. On the contrary, in metakaolin-based GPC, the incomplete geopolymerization led to the compressive strength being too low to meet the application of practical engineering. In addition, the compressive strength of GPC activated by 12 M NaOH was higher than the GPC activated by 8 M NaOH, which is owing to the formation of gel depended on the concentration of alkali OH ion, low NaOH concentration weakened chemical reaction, and reduced compressive strength. Additionally, according to the testing results of neutralization depth, the neutralization depth of high-calcium fly ash-based GPC activated by 12 M NaOH suffered acid attack for 98 d was only 6.9 mm, which is the minimum value. Therefore, the best performance was observed in GPC prepared with high-calcium fly ash and 12 M NaOH solution, which is attributed to gypsum crystals that block the pores of the specimen and improve the microstructure of GPC, inhibiting further corrosion of sulfuric acid

Influence of Alkali-Activators on Acid Rain Resistance of Geopolymer-Recycled Pervious Concrete with Optimal Pore Size

Geopolymer-recycled pervious concrete (GRPC) is a novel concrete that can effectively inhibit the corrosion of acid rain and alleviate urban waterlog. The goal of this study is to ascertain the optimal pore size of GRPC and study its acid rain resistance activated by different alkali-activators. Three different sizes (0.8, 1.0, and 1.2 mm) were separately chosen as the pore diameters of GRPC. The alkali-activator solution adopted sodium hydroxide (NaOH), sodium silicate (Na2SiO3), and a mixture of the two. The mechanical properties and permeability coefficient were tested to determine the optimal pore size of GRPC. After that, specimens with the optimal pore size were immersed in a simulative acid rain solution (sulfuric acid solution with pH = 4.0) for 6 d and were dried 1 d until 56 d. The effects of different alkali activators on acid rain resistance of GRPC were analyzed by compressive strength, neutralization depth, and mass loss. The results manifested that the mechanical properties of GRPC were excellent, the compressive strength of GRPCH+N reached more than 60.1 MPa, and their splitting tensile strength attained more than 5.9 MPa, meeting the strength requirement of the road for heavy traffic load. Considering the mechanical properties and the acid rain purification effect of alkaline GRPC required a relatively small permeability coefficient; the optimal pore size was 1 mm. When specimens with optimal pore size were exposed to acid solution, the corrosion products (gypsums) would block the pores of GRPC to inhibit further corrosion, keeping the stability of the compressive strength. GRPC activated by the mixture of NaOH and Na2SiO3 generated a more stable amorphous three-dimensional network structure, endowing GRPCH+N with better mechanical properties and acid corrosion resistance

The Na/K‐ATPase α1/Src interaction regulates metabolic reserve and Western diet intolerance

AimHighly prevalent diseases such as insulin resistance and heart failure are characterized by reduced metabolic flexibility and reserve. We tested whether Na/K‐ATPase (NKA)‐mediated regulation of Src kinase, which requires two NKA sequences specific to the α1 isoform, is a regulator of metabolic capacity that can be targeted pharmacologically.MethodsMetabolic capacity was challenged functionally by Seahorse metabolic flux analyses and glucose deprivation in LLC‐PK1‐derived cells expressing Src binding rat NKA α1, non‐Src‐binding rat NKA α2 (the most abundant NKA isoform in the skeletal muscle), and Src binding gain‐of‐function mutant rat NKA α2. Mice with skeletal muscle‐specific ablation of NKA α1 (skα1−/−) were generated using a MyoD:Cre‐Lox approach and were subjected to treadmill testing and Western diet. C57/Bl6 mice were subjected to Western diet with or without pharmacological inhibition of NKA α1/Src modulation by treatment with pNaKtide, a cell‐permeable peptide designed by mapping one of the sites of NKA α1/Src interaction.ResultsMetabolic studies in mutant cell lines revealed that the Src binding regions of NKA α1 are required to maintain metabolic reserve and flexibility. Skα1−/− mice had decreased exercise endurance and mitochondrial Complex I dysfunction. However, skα1−/− mice were resistant to Western diet‐induced insulin resistance and glucose intolerance, a protection phenocopied by pharmacological inhibition of NKA α1‐mediated Src regulation with pNaKtide.ConclusionsThese results suggest that NKA α1/Src regulatory function may be targeted in metabolic diseases. Because Src regulatory capability by NKA α1 is exclusive to endotherms, it may link the aerobic scope hypothesis of endothermy evolution to metabolic dysfunction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/1/apha13652.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/2/apha13652-sup-0005-FigS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/3/apha13652-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/4/apha13652_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/5/apha13652-sup-0002-FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/6/apha13652-sup-0003-FigS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168496/7/apha13652-sup-0004-FigS4.pd