A mixed-methods national study investigating key challenges in learning English as a foreign language: A Chinese college student perspective

IntroductionThis mixed-methods national study has a two-fold purpose: (a) to invite Chinese college students to rate their overall difficulties in the eight areas of English learning, i.e., listening, speaking, reading, writing, pronunciation, grammar, vocabulary, and culture; and (b) to invite them to identify their key challenges in learning EFL. Specifically, the following three research questions were asked: (a) what are their overall difficulties in the eight areas of learning EFL? (b) Are there significant differences in rating their overall difficulties in these eight areas across the demographic variables of gender (i.e., male versus female participants) and subject discipline (arts versus sciences versus English subject disciplines participants)? And (c) what are their key challenges in learning EFL?MethodsThe participants included a sample of 1,525 freshmen and sophomore students currently studying at seven universities across China. The instrument was a survey that consisted of a five-point Likert scale self-evaluation form and a major essay question addressing their key challenges. The qualitative data can help to probe deeply into the research setting to obtain in-depth understandings about Chinese college students’ English learning; and therefore, they can greatly enhance the quantitative data.Results and discussionThe quantitative results indicated that listening, speaking, and writing were their three key difficult areas in EFL learning; further, students’ subject discipline (arts versus sciences verse English subject disciplines) had significant effects on their perceived learning challenges in English listening and vocabulary. The qualitative results confirmed that listening, speaking, and writing were their three key challenging areas. Their specific learning challenges in each area were examined. Implications for Chinese college English teachers and administrators are discussed in terms of pedagogy and policy making, respectively

Fabrication of micro/nanometer-channel by Near-Field ElectroSpinning

Direct-written polymer micro/nanofiber from Near- Field ElectroSpinning (NFES) was utilized as shadow-mask to fabricate uniform micro/nanometer-channel. Both Single straight microfiber (line-width 2~10?? m) and nanofiber (diameter 200~800nm) were direct-written on the substrate with the NFES setup, and then 2-nm-thick titanium adhesive layer and 10-nm- thick gold layer were sputtered on the substrate successively. By the ultrasonication process in acetone and de-ionized water, the polymer fiber was removed and micro/nanometer-channel with gap width ranging from 7?? m to 700nm was formed. The fabrication process and related technical issues were also outlined in this work. The experimental results revealed that the micro/nanometer channel had a good uniformity, above 90% of the gap length value lied within the deviation range of ±3%. This simple and facile method can be used to define the uniform micro/nano channel for organic thin film transistors. submicron-gap electrode by using an electrospun single fiber as shadow-mask. This is a simple and cost-effective method, yet the nanofiber used as shadow-mask was obtained through the post-stretching process, which increased the complexity and uncertainty of fabrication process. In this paper, Direct-write (DW) technology (9) based on Near-Field ElectroSpinning (NFES) (10) was utilized to obtain single straight micro/nanofiber directly, and used as shadow- mask to fabricate micro/nanometer-channel. The gap length of micro/nanometer-channel was in the range of 700nm to 7?? m. The fabrication process and related technical issues were described, and then the uniformity of micro/nanometer-channel was also evaluated and discussed

Bead-on-string structure formed by electrohydrodynamic printing

A Bead-on-String (B-S) structure which consists of droplet and filament is generated based on electrohydrodynamic printing system. The formation process of the B-S structure is demonstrated and discussed. Subsequently, the influence of the substrate moving speed on the B-S structure is investigated. The size of the droplet in the B-S structure decreases with the substrate moving speed. When the substrate moving speed is higher than the jetting speed, satellite droplet will appear and its number increases with the substrate moving speed. The effect of the solution concentration on the deposited patterns is also studied. A continuous line is printed with 3 wt% PEO solution. The B-S structure is generated when the concentration of the PEO solution is within 5-15 wt%. Moreover, the size of the droplet decreases with the increasing of the solution concentration. At the concentration of 18 wt%, nanofiber is produced and a pattern similar to the B-S structure is deposited on the substrate

IRAK-M Deficiency Exacerbates Ischemic Neurovascular Injuries in Experimental Stroke Mice

Background: Innate immune response to neuronal death is one of the key events of the pathogenesis of ischemic brain injury. Interleukin-1 receptor-associated kinase (IRAK)-M, encoded by gene Irak3, negatively regulates toll-like receptor signaling by interacting with the MyD88–IRAK-4–IRAK-1 complex and blocking the phosphorylation and dissociation of IRAK-1. Its function in the ischemic stroke is unknown.Objective: This study aims to investigate whether IRAK-M deficiency could exacerbate neuroinflammation and neurovascular injuries during cerebral ischemia and reperfusion.Methods: Male C57BL/6 mice and Irak3 knockout mice were subjected to 45 min of middle cerebral artery occlusion and 4 or 24 h of reperfusion. Transcription of Irak3 gene was evaluated by quantitative real-time PCR (qRT-PCR). Then, infarct volume, neurological score, brain water content, and Evans blue leakage were compared between knock-out and wild-type mice after reperfusion. Through the observation of gross brain specimen after cerebral ischemia, the incidence of hemorrhage transformation was compared between KO and WT mice. To explore underlying signaling pathways involved in IRAK-M deficiency, major proinflammatory cytokines and NF-κB signaling were measured by qRT-PCR and Western blot.Results: The expression of IRAK-M peaked at 1 h after reperfusion, and then gradually decreased within the first 24 h, which was abolished by blocking the expression of hypoxia induced factor 1α. IRAK-M deficiency increased infarct volume, brain edema, the incidence of hemorrhage transformation, and the permeability of blood–brain barrier. In addition, the NF-κB-mediated expressions of proinflammatory cytokines and the activation of microglia in the ipsilateral brain from knock-out mice were much higher than those in wild-type littermates.Conclusion: IRAK-M deletion exacerbates neurovascular damages which are related to the pronounced activation of NF-κB signaling and neuroinflammatory responses during cerebral ischemia-reperfusion in mice. Our study indicates that IRAK-M has neuroprotective effect and has potential to facilitate the development of new pharmaceuticals that reduce neurovascular complications

Interacting Effects Induced by Two Neighboring Pits Considering Relative Position Parameters and Pit Depth

For pre-corroded aluminum alloy 7075-T6, the interacting effects of two neighboring pits on the stress concentration are comprehensively analyzed by considering various relative position parameters (inclination angle θ and dimensionless spacing parameter λ) and pit depth (d) with the finite element method. According to the severity of the stress concentration, the critical corrosion regions, bearing high susceptibility to fatigue damage, are determined for intersecting and adjacent pits, respectively. A straightforward approach is accordingly proposed to conservatively estimate the combined stress concentration factor induced by two neighboring pits, and a concrete application example is presented. It is found that for intersecting pits, the normalized stress concentration factor Ktnor increases with the increase of θ and λ and always reaches its maximum at θ = 90°, yet for adjacent pits, Ktnor decreases with the increase of λ and the maximum value appears at a slight asymmetric location. The simulations reveal that Ktnor follows a linear and an exponential relationship with the dimensionless depth parameter Rd for intersecting and adjacent cases, respectively

Remote sensing monitoring of total suspended solids concentration in Jiaozhou Bay based on multi-source data

Total suspended solids (TSS) concentration (mg/L) is a significant indicator of coastal water environments monitoring. First, quantitative retrieval models of TSS concentrations in Jiaozhou Bay (JZB) were developed based on Landsat and Moderate Resolution Imaging Spectroradiometer (MODIS) data, and the retrieved TSS concentrations in JZB from 1984 to 2021 were obtained. Then, the reliability of the retrieved TSS from Landsat and MODIS was evaluated, and the temporal and spatial variation in TSS concentration was analyzed. Finally, the main factors influencing the variation in TSS concentration in JZB were analyzed. The results show that both Landsat and MODIS retrieval models proposed in this study have good accuracies (Landsat: R2 = 0.64, RMSE = 2.09 mg/L, MAPD = 33.96%; MODIS: R2 = 0.71, RMSE = 2.54 mg/L, MAPD = 32.81%). The TSS concentration in JZB fluctuated between 1984 and 2021, showing a downward trend. The TSS concentration in JZB exhibited an obvious seasonal variation, with a higher concentration in spring and winter owing to strong winds and a lower concentration in summer and autumn. TSS decreased gradually from northwest to southeast. The average spatial variation scale of TSS monitoring in JZB was 72 m and the optimal observation time window was 10:16–12:16. Although the retrieved TSS of Landsat and MODIS were highly consistent (R2 = 0.70, RMSE = 2.09 mg/L), differences were still observed. The exponential function in the retrieval models was the main reason for the large difference between Landsat TSS and MODIS TSS in the nearshore high-value area. The different spatial resolutions, image acquisition times, and signal-to-noise ratios of Landsat and MODIS were also important reasons for the differences. Wind speed was the main factor influencing the annual, seasonal, and monthly variation in TSS concentration in JZB, while the Jiaozhou Bay Bridge only had an effect on the TSS concentration during the construction period

Quantitative correlation between geometric parameters and stress concentration of corrosion pits

Pitting corrosion damage often occurs in aluminum alloy structures and can significantly reduce the service life of structures and cause structural failures. In this research, three-dimensional corrosion pit morphology of 7075-T6 aluminum alloy was observed with the Sensofar PLμ confocal imaging profiler and scanning electron microscope. According to the corrosion pit morphology, we systematically investigated the quantitative correlation between the stress state and geometric features of a corrosion pit idealized as a semi-ellipsoidal pit. It is found that the stress concentration factor (SCF) increases with Rs (the ratio of pit width to length) and Rd (the ratio of pit depth to half-length). The maximum possible SCF is independent of Rd and increases linearly with Rs. The SCF of a rotated pit increases with the orientation angle in a cos2θ relation when Rs < 1.0. The empirical equations are also proposed to correlate the SCF to Rs, Rd and θ