Modelling of railway ballast as a poro-elastic medium and its effects on sleeper sound radiation

Conventional railway track is laid in a layer of coarse stones known as ballast. Due to the gaps between the stones, the railway ballast behaves as a porous acoustic material, with absorptive properties that are important for the noise produced by the railway system. Sound radiated by the bottom of the sleepers may also be transmitted through the ballast. Moreover, during a train pass-by the ballast can vibrate, which may contribute to the radiated noise. To consider all three effects simultaneously, the ballast is treated here as a poro-elastic medium. To obtain the properties of the ballast as a porous medium, transfer function measurements are performed in a vertical impedance tube to determine the surface impedance and absorption coefficient of different depths of reduced scale ballast. The complex wavenumber is also determined through transfer function measurements within the ballast in the vertical tube. Porosity and flow resistivity are determined by non-acoustic measurements, and the Johnson-Champoux-Allard model for porous materials is then fitted to the measured wavenumbers, allowing the remaining parameters to be determined. Comparison is made with the measured impedance and normal incidence absorption coefficient. The model is then used to predict the diffuse field absorption coefficients of both the reduced scale ballast and full-size ballast, which are compared with measurements, showing acceptable agreement. Finally, the effects on the sleeper radiation of introducing the poro-elastic ballast model are estimated and the sensitivity of the results to a practical range of ballast properties is assessed. The ballast vibration increases the sleeper radiation at low frequency, and especially between 120 and 280 Hz. This is caused by the structural vibration of the ballast driven by the sleepers, which has a resonance around 250 Hz. The acoustic velocity within the ballast is 180° out of phase with the structural velocity, and this leads to a small reduction in the sound radiation around 100 Hz. These effects could not be predicted using a surface impedance model for the ballast. Compared with the effect of the ballast vibration and sound transmission, the absorption of the ballast has a much smaller influence on the sleeper radiation

Current Status of Polypharmacy in the Elderly and Its Influencing Factors: a Meta-analysis

Background Polypharmacy is increasingly common in the elderly. The medication compliance of polypharmacy is closely related to its therapeutic effect and safety. Therefore, it is of great significance to understand the medication compliance and its influencing factors in the elderly with polypharmacy at early stage. However, the conclusions of current studies vary greatly, and there is no clear and unified standard. Objective To systematically evaluate the current status of polypharmacy in the elderly and its influencing factors, in order to provide reference for improving medication compliance of polypharmacy in the elderly, reducing adverse reactions, and further developing individualized intervention programs. Methods PubMed, Embase, Web of Science, Cochrane Library, Scopus, Ovid, CBM, CNKI, Wanfang Data and VIP were searched for cohort studies, case-control studies, cross-sectional studies and other observational studies on the influencing factors of medication compliance of polypharmacy in the elderly from inception to March 2023. Two researchers independently screened the literature, evaluated the quality and extracted the data according to the inclusion and exclusion criteria. Stata 17.0 and RevMan 5.3 software were used for meta-analysis. Results A total of 19 studies were included with the total sample size of 130 047 subjects, including 50 852 subjects with good medication compliance. Meta-analysis results showed that the medication compliance rate of polypharmacy in the elderly was 41%〔95%CI (34%, 47%) 〕, which was associated with age〔OR=2.62, 95%CI (1.60, 4.78), P<0.000 1〕, gender〔OR=1.70, 95%CI (1.30, 2.23), P=0.000 1〕, education level〔OR=1.73, 95%CI (1.38, 2.16), P<0.000 01〕, residential lifestyle〔OR=2.85, 95%CI (2.18, 3.72), P<0.000 01〕, medication knowledge level〔OR=1.14, 95%CI (1.04, 1.25), P=0.005〕, medication belief〔OR=2.06, 95%CI (1.44, 2.93), P<0.000 1〕, depression〔OR=2.52, 95%CI (1.96, 3.24), P<0.000 01〕, daily living ability (ADL) 〔OR=2.39, 95%CI (1.68, 3.38), P<0.000 01〕, history of falls〔OR=3.51, 95%CI (2.03, 6.06), P<0.000 01〕, professional guidance 〔OR=3.75, 95%CI (1.92, 7.33), P=0.000 1〕, the number of drug types〔OR=2.58, 95%CI (1.96, 3.41), P<0.000 1〕, adverse drug reactions〔OR=3.08, 95%CI (2.17, 4.38), P<0.000 1〕, medication regimen complexity〔OR=1.08, 95%CI (1.03, 1.14), P=0.004〕, medication management〔OR=1.92, 95%CI (1.34, 2.75), P=0.000 3〕 and medication cost〔OR=2.60, 95%CI (1.30, 5.17), P=0.000 7〕. Sensitivity analysis showed that the results of meta-analysis were relatively stable. Begg's test (P=0.441) and Egger's test (P=0.674) suggested that there was a low risk of publication bias for medication compliance of polypharmacy in the elderly in the included studies. Conclusion The compliance rate of polypharmacy in the elderly is 41%. And the available evidence shows that general factors (age, gender, education level, residential lifestyle), psychological and social factors (depression, ADL, history of falls, medication knowledge level, medication belief, professional guidance), drug factors (medication management, medication cost, medication regimen complexity, the number of drug types, adverse drug reactions) are the influencing factors of medication compliance of polypharmacy in the elderly. Medical staff should formulate individualized intervention measures and optimize disease management in the elderly with polypharmacy according to the influencing factors of medication compliance of polypharmacy

Bacillus velezensis Strain GUMT319 Reshapes Soil Microbiome Biodiversity and Increases Grape Yields

Bacillus velezensis strain GUMT319 is a rhizobacteria biocontrol agent that can control tobacco black shank disease. We took GUMT319 as a biological fertilizer on Vitis vinifera L. The test group was treated with GUMT319 for one year and the control group had a water treatment. Yields of GUMT319-treated grape groups were significantly increased compared to the controls. The average length and width of single grape fruit, weight of 100 grape fruits, the sugar/acid ratio, and the content of vitamin C were all increased in the GUMT319-treated grape group. The pH of the soil was higher and the contents of alkaline hydrolyzable nitrogen and available potassium were significantly lower in the GUMT319-treated groups than the controls. The soil microbial community composition was evaluated by 16S rDNA high-throughput sequencing, and the Shannon index and Simpson index all showed that soil microbes were more abundant in the GUMT319-treated group. These results indicate that GUMT319 is not only a biocontrol agent, but also a plant growth-promoting rihizobacteria. It can increase the yield of grape by altering the physical and chemical properties and the microbial community composition of the soil

Aligned Metal–Organic Framework Nanoplates in Mixed‐Matrix Membranes for Highly Selective CO2/CH4 Separation

Abstract 2D metal–organic frameworks are attractive filler in mixed matrix membranes (MMMs) due to the high aspect ratio and contact opportunity at the filler–polymer interface. However, their alignment in polymer matrix remains a challenge to fully play their functions. Herein, to our best knowledge, for the first time, the facile synthesis of KAUST‐7‐NH2 (KAUST, King University of Science and Technology) nanoplate is reported with 1D channels with an aspect ratio greater than 30. The nanoplates are incorporated and aligned in the 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride‐2,4‐diaminomesitylene (6FDA‐DAM) polymer matrix under the shear force with a filler loading up to 50 wt%. The large difference in adsorption abilities between CO2 and CH4 from the (001)‐oriented KAUST‐7‐NH2 nanoplate‐based MMMs and the favorable interaction at the filler–polymer interface contribute to the excellent CO2/CH4 separation performance. The resultant membranes show CO2/CH4 selectivity with 66.2% enhancement (surpassed 2008 Robeson upper bound), antiplasticization up to 17 bar, and long‐term stability up to 240 h indicating its good potential for natural gas treatment

Additional file 1 of The effect of psychological contract on turnover intention among nurses: a meta-analytic review

Supplementary Material

Highly Pathogenic Avian Influenza Virus (H5N1) Clade 2.3.4.4b Introduced by Wild Birds, China, 2021

Highly pathogenic avian influenza (HPAI) subtype H5N1 clade 2.3.4.4b virus has spread globally, causing unprecedented large-scale avian influenza outbreaks since 2020. In 2021, we isolated 17 highly pathogenic avian influenza H5N1 viruses from wild birds in China. To determine virus origin, we genetically analyzed 1,529 clade 2.3.4.4b H5N1 viruses reported globally since October 2020 and found that they formed 35 genotypes. The 17 viruses belonged to genotypes G07, which originated from eastern Asia, and G10, which originated from Russia. The viruses were moderately pathogenic in mice but were highly lethal in ducks. The viruses were in the same antigenic cluster as the current vaccine strain (H5-Re14) used in China. In chickens, the H5/H7 trivalent vaccine provided complete protection against clade 2.3.4.4b H5N1 virus challenge. Our data indicate that vaccination is an effective strategy for preventing and controlling the globally prevalent clade 2.3.4.4b H5N1 virus