It explores the roles of self-efficacy and self-control in physical activity and Internet addiction. And it further provides a theoretical basis for the treatment and improvement of Internet ...addiction among college students. This study employs the whole group sampling method. The questionnaire was conducted on 855 college students from five universities in three provinces using the Physical Activity Level Scale, the General Self-Efficacy Scale, the Self-Control Scale, and the Chinese Internet Addiction Scale (IAS). The analyses yielded three main findings. (1) A large amount of physical activity was helpful in reducing the symptoms of Internet addiction and the problematic status of each dimension among college students. (2) A large or moderate amount of physical activity was helpful in enhancing college students’ self-efficacy. Besides, a large amount of physical activity was likely to enhance college students’ self-control. (3) The condition of physical activity not only directly has the negative correlation with college students’ Internet addiction but also influences college students’ Internet addiction through two indirect ways: the mediating role of self-control and the chain mediating role of self-efficacy and self-control. These conclusions provide a deeper understanding of the protective factors of Internet addiction among Chinese college students.
Maximum oxygen uptake (VO2max) is a "gold standard" in aerobic capacity assessment, playing a vital role in various fields. However, ratio scaling (Formula: see text), the present method used to ...express relative VO2max, should be suspected due to its theoretical deficiencies. Therefore, the aim of the study was to revise the quantitative relationship between VO2max and body weight (bw). Dimensional analysis was utilized to deduce their theoretical relationship, while linear or nonlinear regression analysis based on four mathematical models (ratio scaling, linear function, simple allometric model and full allometric model) were utilized in statistics analysis to verify the theoretical relationship. Besides, to investigate the effect of ratio scaling on removing body weight, Pearson correlation coefficient was used to analyze the correlation between Formula: see text and bw. All the relevant data were collected from published references. Dimensional analysis suggested VO2max be proportional to Formula: see text. Statistics analysis displayed that four mathematical expressions were VO2max = 0.047bw (p<0.01, R2 = 0.68), VO2max = 0.036bw+0.71 (p<0.01, R2 = 0.76), VO2max = 0.10bw0.82 (p<0.01, R2 = 0.93) and VO2max = 0.23bw0.66-0.48 (p<0.01, R2 = 0.81) respectively. Pearson correlation coefficient showed a significant moderately negative relation between Formula: see text and bw (r = -0.42, p<0.01), while there was no correlation between Formula: see text and bw (r = 0.066, p = 0.41). Although statistics analysis did not fully verify the theoretical result, both dimensional and statistics analysis suggested ratio scaling distort the relationship and power function be more appropriate to describe the relationship. Additionally, we hypothesized that lean mass, rather than body weight, plays a more essential role in eliminating the gap between theoretical and experimental b values, and is more appropriate to standardize VO2max, future studies can focus more on it.
The effects of introducing glass fiber (GF) and/or carbon fiber (CF) filler materials on the friction and wear characteristics of ultra-high molecular weight polyethylene (UHMWPE)-based composites ...were investigated. The composites were evaluated against GCr15 steel under dry and water-lubricated conditions. The goal was to develop an improved material for water-lubricated journal bearings. The friction coefficients of UHMWPE composites were obtained using a pin-on-disc tribometer using sliding speeds ranging from 0.2 to 1.0m/s, contact pressures from 1.0 to 5.0MPa, and two counterface roughness values (Ra=0.1 and 0.3μm). The samples were lubricated by dropping distilled water onto the sliding surface. To evaluate the wear mechanisms, the morphologies of the worn surfaces were examined by scanning electron microscopy and laser 3D micro-imaging profile measurements. In addition, the elemental distribution and content in the transfer film on the GF/UHMWPE composite surface were measured using an energy-dispersive X-ray spectrometer. The results show that glass fibers could effectively reduce the wear rate of composites. In addition, a hybrid filling of glass and carbon fibers could significantly reduce the friction coefficient under water lubrication and dry conditions.
•The tribological behaviors of UHMWPE composites sliding against GCr15 steel under dry conditions and water lubrication were studied.•Hybrid GF and CF fillers can significantly reduce the friction coefficient in different counterface roughness, sliding speed, and normal pressure both for water lubrication and dry friction, for the bulges of fibers support part of the applied load and reduce the contact area.•The wear mechanisms of polymers were analyzed. The results show that GF can effectively reduce the wear rate of the composites for the supporting effect of bulgy glass fiber and the formation of strong back-transfer film.•Quantitative description of the worn surface profile was conducted. The addition of fibers can effectively reduce the counterface roughness by smoothing.
Display omitted
•The PVDF/BiCl3/ZnO nanofibers were prepared via electrospinning technique.•The β-phase content of PVDF/BiCl3/ZnO nanofibers can be achieved as high as 92%.•The peak power density for ...PVDF/BiCl3/ZnO PENG can reach 0.64 μW/cm2.
A unique bismuth chloride (BiCl3)/zinc oxide (ZnO)/poly(vinylidene fluoride) (PVDF) nanofiber-based highly flexible piezoelectric nanogenerator (PENG) is prepared via electrospinning technique. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) are used to characterize the β-phase content and crystallinity of the PVDF based nanofibers, respectively. Then, we analyze four types nanofiber-based PENG (PVDF, PVDF/ZnO(2%), PVDF/BiCl3(2%), and PVDF/BiCl3/ZnO(2%)) and the influence factors of piezoelectric properties are addressed systematically. It is found that the longitudinal piezoelectric coefficient (d33) of PVDF/BiCl3/ZnO(2%) nanofiber-based PENG is up to 3.8 pC/N and an open-circuit voltage (VOC) of 12 V is also got. Finally, the practical applicability of the developed PENG is demonstrated by placing it on elbow and knee joint to monitor human body movement, which shows a maximum peak VOC of 3 V (for elbow) and 0.6 V (for knee) by bending and stretching between specific angles. The high-performance flexible PENG can be used as highly sensitive self-powered sensor, and it also can be used for wearable sensors for detecting some vital signals including breathing, heartbeating, which shows its possible applications in wearable electronics.
This systematic review aimed to evaluate the reliability and validity of the two-point method in predicting 1RM compared to the direct method, as well as analyze the factors influencing its accuracy. ...A comprehensive search of PubMed, Web of Science, Scopus, and SPORTDiscus databases was conducted. Out of the 88 initially identified studies, 16 were selected for full review, and their outcome measures were analyzed. The findings of this review indicated that the two-point method slightly overestimated 1RM (effect size = 0.203 95%CI: 0.132, 0.275; P < 0.001); It showed that test-retest reliability was excellent as long as the test loads were chosen reasonably (Large difference between two test loads). However, the reliability of the two-point method needs to be further verified because only three studies have tested its reliability. Factors such as exercise selection, velocity measurement device, and selection of test loads were found to influence the accuracy of predicting 1RM using the two-point method. Additionally, the choice of velocity variable, 1RM determination method, velocity feedback, and state of fatigue were identified as potential influence factors. These results provide valuable insights for practitioners in resistance training and offer directions for future research on the two-point method.
The article aims to provide references for designing water-lubricated plain journal bearings. Considering the differences between the physical properties of the water and of the oil, the effects of ...eccentricity ratio on pressure distribution of water film are analyzed by computational fluid dynamics (CFD). Then numerical analysis of journal bearings with different dimensions is undertaken under different rotational speeds. Based on the analysis, a reference is produced for selecting the initial diameter dimension which is used to design an efficient water-lubricated plain bearing under the given load and rotational speed. At last, the reference is verified by an experimental case.
This study aims to explore the roles of miR-145/TGFBR2 axis in sepsis-induced acute lung injury. Here, RNA-sequencing assay showed that miR-145 was significantly decreased in exosomes from sepsis ...patient blood samples. And miR-145 was decreased but TGFBR2 was increased in LPS-treated mice lung tissues or BEAS-2B cells in a time-dependent manner. Mechanistically, TGFBR2 was identified as a direct target of miR-145 and the downstream effector Smad3 was also suppressed in BEAS-2B cells with miR-145 overexpression. Pre-injection or post-injection of miR-145 agomir following LPS treatment attenuated LPS-induced inflammation, characterized as the downregulation of IL-2 and TNF-α secretion and ameliorate sepsis, and prolonged the overall survival of septic mice with lung injury. Additionally, TGFBR2 overexpression partially abrogated miR-145-mediated inhibition on LPS-induced inflammation and sepsis-induced acute lung injury. Importantly, TGF-β (Transforming growth factor-β) and miR-145 level displayed a negative correlation in sepsis patients. Thus, these results suggest that miR-145 could ameliorate sepsis-induced lung injury via inhibiting TGFBR2 signaling.
H2S produced in small amounts by mammalian cells has been identified in mediating biological signaling functions. However, the in situ trapping of endogenous H2S generation is still handicapped by a ...lack of straightforward methods with high selectivity and fast response. Here, we encapsulate a semi-cyanine-BODIPY hybrid dye (BODInD-Cl) and its complementary energy donor (BODIPY1) into the hydrophobic interior of an amphiphilic copolymer (mPEG-DSPE), especially for building up a ratiometric fluorescent H2S nanoprobe with extraordinarily fast response. A remarkable red-shift in the absorption band with a gap of 200 nm in the H2S response can efficiently switch off the Förster resonance energy transfer (FRET) from BODIPY1 to BODInD-Cl, subsequently recovering the donor fluorescence. Impressively, both the interior hydrophobicity of supramolecular micelles and electron-withdrawing nature of indolium unit in BODInD-Cl can sharply increase aromatic nucleophilic substitution with H2S. The ratiometric strategy based on the unique self-assembled micellar aggregate NanoBODIPY achieves an extremely fast response, enabling in situ imaging of endogenous H2S production and mapping its physiological and pathological consequences. Moreover, the amphiphilic copolymer renders the micellar assembly biocompatible and soluble in aqueous solution. The established FRET-switchable macromolecular envelope around BODInD-Cl and BODIPY1 enables cellular uptake, and makes a breakthrough in the trapping of endogenous H2S generation within raw264.7 macrophages upon stimulation with fluvastatin. This study manifests that cystathione γ-lyase (CSE) upregulation contributes to endogenous H2S generation in fluvastatin-stimulated macrophages, along with a correlation between CSE/H2S and activating Akt signaling pathway.
Glass fiber-reinforced polymer (GFRP) composites are promising composites often utilized in coastal infrastructure or used as an alternative to steel reinforcement in seawater sea sand concrete due ...to their excellent corrosion resistance. Understanding the degradation mechanism of GFRP in corrosion environments is significant for improving the long-term performance of GFRP materials. This paper presented the influences of seawater content and temperature on the properties of GFRP composites using the molecular dynamics method. The simulation results were validated by existing experiments on mechanical properties, interlaminar strength, and microstructures of an accelerated aging test of GFRP. The calculation results indicated that when seawater content of the matrix increased from 0% to 9.09% at 298 K, Young’s modulus, shear modulus, and bulk modulus decreased 46.72%, 53.46%, and 41.75%, respectively. The binding energy of GFRP composites with seawater content of 2.15% at 353 K was 26.46% lower than that of unconditioned GFRP at 298 K. It revealed that the higher seawater content and temperature accelerated the degradation of the GFRP composites. The investigation provided a comprehensive understanding of the degradation mechanism of GFRP in seawater environments and provided a basis for the durability design of GFRP composites.
Hepatology and drug development for liver diseases require in vitro liver models. Typical models include 2D planar primary hepatocytes, hepatocyte spheroids, hepatocyte organoids, and ...liver-on-a-chip. Liver-on-a-chip has emerged as the mainstream model for drug development because it recapitulates the liver microenvironment and has good assay robustness such as reproducibility. Liver-on-a-chip with human primary cells can potentially correlate clinical testing. Liver-on-a-chip can not only predict drug hepatotoxicity and drug metabolism, but also connect other artificial organs on the chip for a human-on-a-chip, which can reflect the overall effect of a drug. Engineering an effective liver-on-a-chip device requires knowledge of multiple disciplines including chemistry, fluidic mechanics, cell biology, electrics, and optics. This review first introduces the physiological microenvironments in the liver, especially the cell composition and its specialized roles, and then summarizes the strategies to build a liver-on-a-chip via microfluidic technologies and its biomedical applications. In addition, the latest advancements of liver-on-a-chip technologies are discussed, which serve as a basis for further liver-on-a-chip research.
PDF
