To understand the relationship between smartphone addiction and academic procrastination and the mechanisms at work within this relationship, this study constructs a mediation model to examine the ...impact of college students' smartphone addiction on their academic procrastination and the mediation effect of academic self-efficacy. A total of 483 college students were surveyed using the Smartphone Addiction Scale—Short Version, College Academic Self-Efficacy Scale and Tuckman Academic Procrastination Scale. Correlation analysis showed that smartphone addiction was positively related to academic procrastination while being negatively related to academic self-efficacy. At the same time, academic self-efficacy and academic procrastination were negatively related. Further, mediation analysis using the PROCESS plugin in SPSS showed that smartphone addiction has a direct predictive effect on students’ academic procrastination and an indirect predictive effect via academic self-efficacy after controlling for age, gender, and academic year. Specifically, academic self-efficacy was found to be a partial mediator and play a buffering role between smartphone addiction and academic procrastination.
•Smartphone addiction has a direct predictive effect on students' academic procrastination.•Smartphone addiction negatively predicts college students' academic self-efficacy.•There is a negative association between academic self-efficacy and academic procrastination.•Academic self-efficacy plays a mediating and buffering role between smartphone addiction and academic procrastination.
Tectonic evolution of the North China Craton underwent a complicated process during the early Mesozoic owing to almost simultaneous closures of the Mianlue Ocean to the south and the Palaeo-Asian ...Ocean to the north. The tectonic setting of the Triassic sedimentary basin in the southern North China Craton remains a subject of debate. The conventional view is that early Mesozoic basins resulted from plate collision and crustal shortening, whereas new petrological evidence of crustal extension has been identified in the southern North China Craton. In this study, we used petrology, sedimentology, subsidence and geochronology to trace basin provenance and reconstruct source-to-sink around the southeast Ordos Basin. The petrographic modal compositions showed that the provenance changed from recycled orogenic to a mixture of recycled orogenic and arc magmatic materials. Tectonic subsidence of the southeast Ordos Basin revealed two episodes of rapid subsidence, the second of which lasted ~10 Ma and caused the depocenter of the basin to move southward. Early Triassic detrital zircons with distinguishing ages of 1100–700 Ma were derived from the Central China Orogenic Belt and North China Craton; then, they were sourced from the Inner Mongolia Palaeo-uplift, based on zircon ages clustered at ~400–250 Ma. The petrographic modal composition, tectonic subsidence and zircon age distribution imply a provenance shift from short and rapid uplift (North Qinling Orogenic Belt) to remote continuous uplift (Inner Mongolia Palaeo-uplift); this is also supported by the palaeo-current direction. This shift defined a change in the Qinling Orogenic Belt from collision and uplift to extension, which caused the depositional centre of the Ordos Basin to move southward. This integrated tectono-sedimentary environment study provides new insight into the closure process of the Mianlue Ocean during the Triassic and its impact on the tectonic environment of the southern North China Craton.
•Early Triassic uplift of the North Qinling Belt affected the basin provenance.•Inner Mongolia Palaeo-Uplift regained control of the provenance after 247.2 Ma.•Southward progradation of fluvial-deltaic facies appeared after 247.2 Ma.•Provenance shift during the Triassic was a response to crustal stretching.
Carbon-bridge-modified malonamide (MLD)/g-C3N4 (CN) was prepared by copolymerization of MLD with urea and melamine and loaded with Fe3O4 for the high-efficiency removal of tetracycline (TC) in water ...under photo-Fenton. The prepared catalysts were characterized by SEM, TEM, N2 adsorption–desorption analysis, XPS, XRD, and FTIR, which proved that the modification method successfully introduced the C bridge into the carbon nitride molecular system and increased the structural defects of the catalyst. The Carbon-bridge-modified MLD/CN/Fe3O4 also had good visible-light response and charge-separation and transport abilities in the photoelectrochemical test. Degradation results showed that the photo-Fenton degradation of TC reached 95.8%, and the mineralization rate was 55.7% within 80 min at 80 mM H2O2 dosage, 0.5 g/L catalyst dosage, and near-neutral pH by 0.8MLD/CN/Fe3O4. Moreover, the oxidation products and mineralization pathways of TC were explored by LC-MS. Toxicity analysis indicated low environmental threat of the intermediates in TC mineralization. EPR analysis and H2O2 decomposition efficiency analyses showed an improvement in the H2O2 decomposition performance of 0.8MLD/CN/Fe3O4. This work could provide a valuable insight for the application of heterogeneous photo-Fenton technology in wastewater treatment.
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•A carbon-bridge modified MLD/CN/Fe3O4 catalyst was successfully synthesized by copolymerization.•Carbon-bridge implantation significantly improved the charge separation performance of the catalyst.•0.8MLD/CN/Fe3O4 has good degradation performance for TC under photo-Fenton within a wide pH range.•The mechanism of enhanced decomposition of H2O2 and degradation of TC was proposed.
Abstract
In this work, CeO
2
nanosheets decorated with Ag
2
O and AgBr are successfully fabricated via a simple sediment-precipitation method. The as-prepared ternary Ag
2
O/AgBr–CeO
2
composite with ...double Z-scheme construction was analyzed by various analytical techniques. Ag nanoparticles (NPs) used as the electron medium could reduce the recombination of photoelectrons and holes, thus leading to the improvement of photocatalytic performance of these catalysts. Due to the unique structure and composite advantages, the optimal Ag
2
O/AgBr–CeO
2
photocatalysts exhibit the superior tetracycline (TC) degradation efficiency of 93.23% and favorable stability with near-initial capacity under visible light irradiation. This ternary Z-scheme structure materials will be the well-promising photocatalysts or the purification of antibiotic wastewater.
Urban heat island (UHI) can be characterized and quantified to understand the modification of urban surfaces on the local and regional climate. This study examines UHI variation across three ...megacities that are located in rapid urbanization regions in eastern China (Beijing, Shanghai and Guangzhou). These cities are located within a warm temperate climate zone, north subtropical climate zone, and lower subtropical climate zone, respectively. Satellite-based land surface temperature (LST) data and air temperature records from 2003 to 2016 were used to identify surface urban heat island (SUHI) and canopy urban heat island (CUHI), respectively. Generally, the average annual SUHI is higher than the CUHI, with the greatest UHIs appearing in Beijing (SUHI: 2.33 ± 0.18 °C, CUHI: 1.45 ± 0.54 °C). UHI changes across latitudes were negatively related to humidity variation, with higher UHI in drier climates. Seasonal UHI analysis suggests that a lower SUHI would occur in winter and a higher UHI in spring and summer, except for Guangzhou. CUHI in dry season was higher than in wet season for all three megacities, and the largest CUHI (2.10 ± 0.33 °C) appeared in winter in Beijing. Various patterns of seasonal cycles of SUHI and CUHI were related to monthly precipitation and solar insolation. Annual average daytime SUHI was higher than the nighttime SUHI, and larger daytime SUHI appeared in Guangzhou, contrasting with Shanghai and Beijing. The difference between SUHI and CUHI for all seasons was also high in Guangzhou. UHI changes were considered to be altered by warm and wet conditions in mega-cities of eastern China, and heat transportation from urban surface to urban canopy provided some possible understanding of the UHI change.
Circular RNAs (circRNAs), a novel type of non-coding RNAs (ncRNAs), have a covalently closed circular structure resulting from pre-mRNA back splicing via spliceosome and ribozymes. They can be ...classified differently in accordance with different criteria. As circRNAs are abundant, conserved, and stable, they can be used as diagnostic markers in various diseases and targets to develop new therapies. There are various functions of circRNAs, including sponge for miR/proteins, role of scaffolds, templates for translation, and regulators of mRNA translation and stability. Without m7G cap and poly-A tail, circRNAs can still be degraded in several ways, including RNase L, Ago-dependent, and Ago-independent degradation. Increasing evidence indicates that circRNAs can be modified by N-6 methylation (m6A) in many aspects such as biogenesis, nuclear export, translation, and degradation. In addition, they have been proved to play a regulatory role in the progression of various cancers. Recently, methods of detecting circRNAs with high sensitivity and specificity have also been reported. This review presents a detailed overview of circRNAs regarding biogenesis, biomarker, functions, degradation, and dynamic modification as well as their regulatory roles in various cancers. It's particularly summarized in detail in the biogenesis of circRNAs, regulation of circRNAs by m6A modification and mechanisms by which circRNAs affect tumor progression respectively. Moreover, existing circRNA detection methods and their characteristics are also mentioned.
Photothermal therapy (PTT) offers many advantages such as high efficiency and minimal invasiveness, but clinical adoption of PTT nanoagents have been stifled by unresolved concerns such as the ...biodegradability as well as long-term toxicity. Herein, poly (lactic-co-glycolic acid) (PLGA) loaded with black phosphorus quantum dots (BPQDs) is processed by an emulsion method to produce biodegradable BPQDs/PLGA nanospheres. The hydrophobic PLGA not only isolates the interior BPQDs from oxygen and water to enhance the photothermal stability, but also control the degradation rate of the BPQDs. The in vitro and in vivo experiments demonstrate that the BPQDs/PLGA nanospheres have inappreciable toxicity and good biocompatibility, and possess excellent PTT efficiency and tumour targeting ability as evidenced by highly efficient tumour ablation under near infrared (NIR) laser illumination. These BP-based nanospheres combine biodegradability and biocompatibility with high PTT efficiency, thus promising high clinical potential.
2D titanium disulfide (TiS2) is recently found to have strong light absorption properties from visible to infrared (IR) region. This feature is highly attractive for applications in nonlinear ...photonics; however, the mechanism of broadband light–matter interaction is yet to be determined and nonlinear photonic devices are not developed. Here, for the first time, the experimental evidence supporting the mechanism of the broadband nonlinear photoresponse in ultrathin TiS2 nanosheets ranging from 400 nm to 1390 nm is reported through laser Z‐scan measurements. High‐performance nonlinear photonic devices operating in the telecommunication band are also demonstrated. A novel saturable absorber (SA) device is successfully fabricated based on a 2D TiS2‐decorated fiber, which exhibits outstanding ultrashort pulse generation performance with pulse duration of ≈1.04 ps centered at 1569.5 nm. Furthermore, as a stable all‐optical thresholding component, the device can effectively attenuate noise and boost the signal‐to‐noise ratio of the pulse from 1.90 to 10.68 dB. The findings indicate that TiS2‐based SA devices can be developed into excellent highly nonlinear photonic devices, which may advance the development of TiS2‐based optical communication technologies in the future.
Ultrathin and uniform semimetallic titanium disulfide nanosheets are synthesized via a colloidal chemistry method. A Z‐scan system is used to confirm their broadband nonlinear optical response from visible to mid‐infrared wavelengths. Thus, TiS2 nanosheet‐based optical devices exhibit excellent performance in mode‐locked fiber lasers and all‐optical thresholding components.
Ultrasmall black phosphorus quantum dots (BPQDs) with an average size of 2.1 ± 0.9 nm are synthesized by using a solvothermal method in a N‐methyl‐2‐pyrrolidone solution. Verified by femto‐second ...laser Z‐scan measurement, BPQDs exhibit excellent nonlinear optical response with a modulation depth of about 36% and a saturable intensity of about 3.3 GW cm−2. By using BPQDs as optical saturable absorber, the ultrashort pulse with a pulse duration of about 1.08 ps centered at a wavelength of 1567.5 nm is generated in mode‐locked fiber laser. These results suggest that BPQDs may be developed as another kind of promising nanomaterial for ultrafast photonics.
A solvothermal synthesis is decribed to produce ultrasmall black phosphorus quantum dots (BPQDs) in large scale. BPQDs exhibit excellent nonlinear optical response and are used as optical saturable absorber. The ultrashort pulse with a pulse duration of about 1.08 ps centered at a wavelength of 1567.5 nm is generated by a mode‐locked fiber laser.
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