•Cotransport of HMs and SPs is investigated at different temperatures by seepage.•A model considering the particle size and dielectric property is developed.•This model can predict the transport ...processes for variable injection concentration.
The cotransport of heavy metals (HMs; i.e., Pb2+ and Cd2+) and SiO2 suspended particles (SPs) in a porous medium (quartz sand) at different temperatures was investigated by one-dimensional laboratory column experiments. Considering the significant differences in particle size and dielectric property between HMs and SPs, a theoretical model describing their cotransport was developed in this study. The results show that temperature and Darcy velocity have a negligible effect on the transport of individual HMs and that the recovery ratio of Cd2+ is higher than that of Pb2+, which can be attributed to the lower adsorption of Cd2+ on the solid matrix. The presence of SPs can facilitate the transport of HMs due to the strong adsorption of positively charged HMs on negatively charged SPs. However, this effect tends to decrease with the size of the SiO2 particles. An increase in temperature (e.g., T = 20 → 60 °C) results in a decrease in the recovery ratio of HMs because more HMs adsorbed on SPs can be deposited at high temperatures. The adsorption of HMs on SPs can also change the dielectric properties of the SPs, thus causing a reduction in the repulsion between the SPs and the solid matrix and a consequent decrease in the recovery ratio of SPs. In addition, the results show that the developed model fits well with the experimental results.
Italy is one of the first European epicenters of the COVID-19 pandemic. In attempts to hinder the spread of the novel coronavirus disease, Italian government hardened protective measures, from ...quarantine to lockdown, impacting millions of lives dramatically. Amongst the enacted restrictions, all non-essential activities were prohibited as well as all outdoor activities banned. However, at the first spur of the outbreak, for about a dozen of days, physical and sports activities were permitted, while maintaining social distancing. In this timeframe, by administering measures coming from self-determination theory and theory of planned behavior and anxiety state, in an integrated approach, we investigated the prevalence of these activities by testing, via a Structural Equation Model, the influence of such psychosocial variables on the intention to preserve physical fitness during the healthcare emergency. Through an adequate fit of the hypothesized model and a multi-group analysis, we compared the most COVID-19 hit Italian region - Lombardy - to the rest of Italy, finding that anxiety was significantly higher in the Lombardy region than the rest of the country. In addition, anxiety negatively influenced the intention to do physical activity. Giving the potential deleterious effects of physical inactivity due to personal restrictions, these data may increase preparedness of public health measures and attractiveness of recommendations, including on the beneficial effects of exercise, under circumstances of social distancing to control an outbreak of a novel infectious disease.
At present, many scholars are experimentally investigating the grinding performance of ceramic matrix composites (C–SiCs). However, accurately reflecting the microscopic mechanisms of crack ...initiation and extension and the material removal mechanism (MRM) is difficult. To research the micro-MRM of C–SiCs, a theoretical model (TTM) and a numerical simulation model (NSM) were established in this study and were proven to be reliable by experiments. The TTM was established according to the kinematics and dynamics of a single abrasive particle. In the procedure of establishing the NSM, the SiC matrix (SiCM) and carbon fibre reinforcement (CFRT) were each modelled based on the internal structure characteristics of C–SiCs and then combined by an interface layer. The TTM, NSM and verification experiments all showed that fibre pull-out, fibre outcrop, matrix cracking and interfacial debonding were the basic defects in the C–SiCs. As the grinding depth (ap) increased, the grinding performance of the C–SiCs gradually deteriorated. The material removal characteristics of C–SiCs can be directly modelled at the microlevel by the NSM. The NSM showed that the grinding force fluctuated periodically because the CFRT and SiCM have different properties. High stresses occurred mainly in the SiCM. This research can supply a scientific basis for understanding the micro-MRM of C–SiCs and provide important guidance for the high-quality grinding of C–SiCs.
•The bioactivity of organic compounds was firstly investigated.•Activity of molecules were theoretically computed by the DFT.•The organic compounds have two synergetic antibacterial pharmacophore ...sites.•The bioactivity against cancer proteins were compared with the studied compounds.•Pharmacological properties were theoretically computed by the POM calculations.
In this present research work, new 8-hydroxyquinoline derivatives were synthesized and their molecular structures were confirmed by the 1H NMR, 13C NMR, IR and elemental analysis. The antioxidant activity of the synthesized compounds is evaluated through their capacity to scavenge 2,2-di-phenyl-1-picrylhydrazyl (DPPH) free radicals. In addition, their antibacterial activity was examined against bacterial strains of S. aureus, K. pneumonia, and E. coli. The obtained results showed that the antibacterial activity of studied compounds for Gram-positive and Gram-negative is higher than Penicillin G. The theoretical properties of selected compounds was computed by the DFT method. POM analysis (Petra/Osiris/Molinspiration) of studied molecules has been done. Their biological activities were compared against breast, liver and lung cancer proteins. The obtained results showed the synthesized derivatives were effective antibacterial and antioxidant agents against various biological material.
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•A group of novel hierarchical multi-cell tubes (NHMTs) are proposed by replacing every sides of traditional multi-cell tubes with smaller square cells to improve energy absorption capacity of ...multi-cell tubes (TMTs).•The energy-absorption capacity of NHMTs is superior to the TMTs under the same mass, and their energy-absorption capacity improve gradually with the hierarchical level.•A theoretical model of NHMTs is established and validated to predict the energy absorption performance of NHMTs under axial crushing loading.
In recent years, the concept of hierarchy has been introduced into crashworthy design to explore an ultralight energy-absorbing structure with outstanding mechanical properties. In this study, a group of novel hierarchical multi-cell tubes (NHMTs) are proposed by replacing every sides of traditional multi-cell tubes with smaller square cells. The finite element model of NHMTs is first established and validated by experimental test. Then, the crashworthiness performance of NHMTs is analyzed and compared with taditional multi-cell tubes (TMTs). The results indicate that NHMTs exhibit superior crashworthiness behavior than TMTs and the hierarchical level has significant effect on the crashworthiness of NHMTs. Furthermore, in order to analyze energy absorption mechanism of NHMTs, the theoretical models of specific energy absorption (SEA) and mean crushing force (MCF) are established and validated. The result shows that the theoretical model of SEA and MCF can accurately predict the energy absorption behavior of NHMTs. This investigation offers a novel technique to design multi-cell tubes with excellent energy absorption capacity.
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•Eccentric behaviors of ECC-encased CFST columns after fire exposure were investigated.•Comparisons were made between ECC-encased CFST and concrete-encased CFST columns.•The influences of different ...parameters on ECC-encased CFST columns were discussed.•A theoretical model was proposed to predict the residual eccentric load strength.
This paper intends to investigate the mechanical behaviors of eccentrically loaded engineered cementitious composite (ECC)-encased concrete filled steel tube (CFST) columns after fire exposure. Totally seven ECC-encased CFST columns and one concrete-encased CFST column were designed and tested with the consideration of different parameters, i.e., heating-up time, eccentricity ratio, stirrup spacing and longitudinal reinforcement ratio. It was found that the severe concrete spalling was noticed for concrete-encased CFST column, while the integrity of ECC-encased CFST column was well maintained under identical fire-exposed circumstances. After fire exposure for 45 min, the eccentric load carrying capacity and flexural stiffness of ECC-encased CFST column are 57.8 % and 63.5% higher than that of concrete-encased CFST column, respectively. A theoretical model was proposed to predict the residual eccentric load strength of ECC-encased CFST columns after fire exposure, and the maximum error of the calculation result was within 12 %.
Exposure of biological cells to high-voltage, short-duration electric pulses causes a transient increase in their plasma membrane permeability, allowing transmembrane transport of otherwise ...impermeant molecules. In recent years, large steps were made in the understanding of underlying events. Formation of aqueous pores in the lipid bilayer is now a widely recognized mechanism, but evidence is growing that changes to individual membrane lipids and proteins also contribute, substantiating the need for terminological distinction between electroporation and electropermeabilization. We first revisit experimental evidence for electrically induced membrane permeability, its correlation with transmembrane voltage, and continuum models of electropermeabilization that disregard the molecular-level structure and events. We then present insights from molecular-level modeling, particularly atomistic simulations that enhance understanding of pore formation, and evidence of chemical modifications of membrane lipids and functional modulation of membrane proteins affecting membrane permeability. Finally, we discuss the remaining challenges to our full understanding of electroporation and electropermeabilization.
Electrochemical noise (EN) can be used in situ to investigate corrosion processes and to detect and monitor the corrosion of metallic materials. EN data are largely influenced by the measurement ...mode, the surface area of the working electrodes, the electrolyte resistance, and the symmetry of the electrode system. Herein, the advantages and limitations of electrochemical kinetics, equivalent circuit, and shot noise methods for quantifying corrosion rates with EN are discussed.
Since the publication of Standards for QUality Improvement Reporting Excellence (SQUIRE 1.0) guidelines in 2008, the science of the field has advanced considerably. In this manuscript, we describe ...the development of SQUIRE 2.0 and its key components. We undertook the revision between 2012 and 2015 using (1) semistructured interviews and focus groups to evaluate SQUIRE 1.0 plus feedback from an international steering group, (2) two face-to-face consensus meetings to develop interim drafts and (3) pilot testing with authors and a public comment period. SQUIRE 2.0 emphasises the reporting of three key components of systematic efforts to improve the quality, value and safety of healthcare: the use of formal and informal theory in planning, implementing and evaluating improvement work; the context in which the work is done and the study of the intervention(s). SQUIRE 2.0 is intended for reporting the range of methods used to improve healthcare, recognising that they can be complex and multidimensional. It provides common ground to share these discoveries in the scholarly literature (http://www.squire-statement.org).
•The main content of this study is to investigate the coupled effects of blade sweep and radial distortion on flow stability.•Steady numerical simulations, theoretical model predictions, and ...experimental validations were conducted.•The use of a linear flow stability model based on small disturbance theory predicted the stall inceptions with high accuracy.•Higher intensities of distortion lead to worse flow stability. Under radially distorted inlet conditions, forward sweep enhances flow stability whereas backward sweep further worsens it. The stability enhancement of forward sweep cannot fully counteract the adverse impact of radial distortion on flow stability.•Elevated rotor tip loading was identified as the primary cause of instability under tip total pressure distorted inlet conditions. Forward sweep can slightly reduce this loading, whereas backward sweep has the opposite effect. Furthermore, the impact of rotor sweep on rotor tip loading intensifies with increasing distortion intensity.
Flow stability enhancement for axial flow compressors under radially distorted inlet conditions through rotor sweep design is an important issue for designers. To investigate the couped effect of rotor swept and radial inlet distortion on flow stability, steady numerical simulations, theoretical model predictions, and experimental validations were conducted for a low-speed, single-stage axial compressor (TA36) under various intensities of tip total pressure distorted inlet conditions with different swept rotor configurations. The steady pressure rise significantly decreases as the intensity of the distortion increases, whereas the rotor sweep has little effect on the pressure rise characteristic. The maximum error via model prediction is 1.25 %, while for steady numerical calculation, it is 3.89 %. Higher intensities of distortion lead to worse flow stability. Under radially distorted inlet conditions, forward sweep enhances flow stability whereas backward sweep further worsens it. What's more, quantitative analysis shows that the stability enhancement of forward sweep cannot fully counteract the adverse impact of radial distortion on flow stability. Elevated rotor tip loading was identified as the primary cause of instability under tip total pressure distorted inlet conditions. Forward sweep can slightly reduce this loading, whereas backward sweep has the opposite effect. Furthermore, the impact of rotor sweep on rotor tip loading intensifies with increasing distortion intensity. Unsteady flow field analysis was conducted. Which shows that radial distortion and blade sweep both affect flow stability by altering the intensity of tip leakage flow.
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