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The COVID-19 pandemic caused school closures and social isolation, which created both learning and emotional challenges for adolescents. Schools worked hard to move classes online, but less attention was paid to whether students were cognitively and emotionally ready to learn effectively in a virtual environment. This study focused on online learning readiness and emotional competence as key constructs to investigate their implications for students’ academic performance during the COVID-19 period. Two groups of students participated in this study, with 1,316 high school students (Mean age = 16.32, SD = 0.63) representing adolescents and 668 college students (Mean age = 20.20, SD = 1.43) representing young adults. Structural equation modeling was conducted to explore the associations among online learning readiness, emotional competence, and online academic performance during COVID-19 after controlling for pre–COVID-19 academic performance. The results showed that, for high school students, both online learning readiness and emotional competence were positively associated with online academic performance during COVID-19. However, for college students, only online learning readiness showed a significant positive relationship with online academic performance during COVID-19. These results demonstrated that being ready to study online and having high emotional competence could make adolescents more resilient toward COVID-19–related challenges and help them learn more effectively online. This study also highlighted different patterns of associations among cognitive factors, emotional factors, and online academic performance during COVID-19 in adolescence and young adulthood. Developmental implications were also discussed.

A considerable number of empirical studies have led researchers to identify key characteristics that indicate effective professional development (PD). However, few studies have attended to teacher ...

Parthenocarpy can be induced by gibberellin (GA) treatment in plants. The fruits of the loquat exhibit many seeds. GA treatment can induce the development of seedless fruit and increase fruit quality during production. However, the molecular mechanism of fruit setting under GA treatment is still unclear. Our aim was to explore GA-induced parthenocarpy in triploid loquat by proteome analysis to identify the differentially expressed proteins. A proteome analysis was performed using TMT protein labeling and LC-MS/MS in triploid loquat. A total of 7290 protein groups were identified in the two stages of fruit setting. The quantitative results showed that 923 differentially expressed proteins (DEPs) were isolated, which were enriched in five pathways: ribosome, citrate cycle (TCA cycle), pentose phosphate, carbon metabolism, and carbon fixation. Twenty-four DEPs were annotated as putative key regulatory proteins involved in fruit setting, which were related to the auxin response, gibberellin metabolism, ethylene synthesis, and cell division. In addition, thirty-five DEPs were involved in the formation of the cell wall, which might be downstream proteins involved in cell proliferation during fruit setting. Our report reveals new insight into the protein dynamics of loquat fruit setting induced by GA treatment via the analysis of proteome profiles and provides a reference for other Rosaceae species.

Flowering is an important phenophase of plant species, however, knowledge about the regulatory mechanism controlling flowering cues in loquat is limited. To identify candidate genes regulating flowering time in loquat, we used RNA-Seq technology to conduct a comparative transcriptome analysis of differentiating apical buds collected from the early-flowering variety ‘Baiyu’ and the late-flowering variety ‘Huoju’. A total of 28,842 differentially expressed transcripts (DETs) were identified. Of these, 42 DETs controlled flowering time while 17 other DETs were associated with the ABA signaling pathway. Compared with those in ‘Huoju’, EjFT, EjFY, EjFLK, and EjCAL1-like were significantly upregulated in ‘Baiyu’. Moreover, transcripts of the ABA 8′-hydroxylases (EjABH2, EjABH4, and EjABH4-like2), the ABA receptors (EjPYL4/8), and the bZIP transcription factor EjABI5-like were upregulated in ‘Baiyu’ compared with ‘Huoju’. Hence, they might regulate loquat flowering time. There was no significant difference between ‘Baiyu’ and ‘Huoju’ in terms of IAA content. However, the ABA content was about ten-fold higher in the apical buds of ‘Baiyu’ than in those of ‘Huoju’. The ABA:IAA ratio sharply rose and attained a peak during bud differentiation. Thus, ABA is vital in regulating floral bud formation in loquat. The results of the present study help clarify gene transcription during loquat flowering.

The variable anatomy of Ebstein’s anomaly leads to its various surgical procedures. The long-term outcomes of different operations were not well established. Thirty-five patients with Ebstein’s anomaly who underwent operations from 2006 to 2018 in our department were retrospectively reviewed. Individualized surgical plans were performed according to the preoperative echocardiography and surgeons’ preference. Tricuspid repair, either Danielson’s or Carpentier’s technique, was the primary choice in patients who had sufficient tricuspid leaflets and adequate right ventricle, while tricuspid replacement was used when a reliable repair is not achievable. Additional bidirectional cavopulmonary shunt was performed in those who had unstable hemodynamics despite of high central venous pressure after separation from cardiopulmonary bypass. The perioperative and follow-up data were collected. The age was 26.9 (0.6–54) years [16 children (age

Background Propagation of cuttings is frequently used in various plant species, including blueberry, which shows special root characteristics that may hinder adventitious root (AR) formation. AR formation is influenced by various factors, and auxin is considered to play a central role; however, little is known of the related regulatory mechanisms. In this study, a comparative transcriptome analysis of green cuttings treated with or without indole-butyric acid (IBA) was performed via RNA_seq to identify candidate genes associated with IBA-induced AR formation. Results Rooting phenotypes, especially the rooting rate, were significantly promoted by exogenous auxin in the IBA application. Blueberry AR formation was an auxin-induced process, during which adventitious root primordium initiation (rpi) began at 14 days after cutting (DAC), root primordium (rp) was developed at 21 DAC, mature AR was observed at 28 DAC and finally outgrowth from the stem occurred at 35 DAC. Higher IAA levels and lower ABA and zeatin contents might facilitate AR formation and development. A time series transcriptome analysis identified 14,970 differentially expressed genes (DEGs) during AR formation, of which there were 7467 upregulated and 7503 downregulated genes. Of these, approximately 35 candidate DEGs involved in the auxin-induced pathway and AR formation were further identified, including 10 auxin respective genes (ARFs and SAURs), 13 transcription factors (LOB domain-containing protein (LBDs)), 6 auxin transporters (AUX22, LAX3/5 and PIN-like 6 (PIL6s)) and 6 rooting-associated genes (root meristem growth factor 9 (RGF9), lateral root primordium 1 (LRP1s), and dormancy-associated protein homologue 3 (DRMH3)). All these identified DEGs were highly upregulated in certain stages during AR formation, indicating their potential roles in blueberry AR formation. Conclusions The transcriptome profiling results indicated candidate genes or major regulatory factors that influence adventitious root formation in blueberry and provided a comprehensive understanding of the rooting mechanism underlying the auxin-induced AR formation from blueberry green cuttings.

Grafting is a common method of variety propagation in loquat breeding, the slow growth of rootstocks is a main factor limiting the expansion of this technique. This study aimed to evaluate the effects of seven different fertilizer formulas on the growth of loquat rootstock seedlings, five water-soluble fertilizer formulas, as well as organic fertilizer and controlled-release fertilizer were evaluated. An unfertilized control (CK) was also performed. Growth indicators including plant height, stem thickening and lignification, leaf area, root development, dry matter accumulation, spatial distribution of nutrient elements, and cross-sectional anatomy of stem were measured. The results showed that the addition of microelements in fertilizer could significantly delay the lignification process of the cambium, which exhibiting the greatest improvement in stem thickening. Phosphorus nutrition could significantly promote the occurrence of fibrous roots, while excessive phosphorus supply might disturb the absorption and utilization of nitrogen of roots, intensify the lignification process of the main stem, and then affect the growth of the aboveground part. The findings of this research could provide a theoretical basis for identifying an optimum fertilization formula and technique for promoting the rapid growth and accelerating the lignification process at different stages of loquat rootstock seedling growth.

Additional file 9: Table S1 Regression equation of the calibration curves for IAA, ABA, GA3 and zeatin.

Additional file 10: Table S2 Primers for the qRT-PCR analysis used in this study.

Aluminum (Al) toxicity associated with acid soils represents one of the biggest limitations to crop production worldwide. The root apex of plants is the major perception site of Al toxicity. In Al stressed wheat primary roots, Al accumulation and loss of plasma membrane integrity were highest in the root apex (0–5 mm), and decreased along the root axis (5–25 mm). To further understand these responses in wheat, spatial profiles of antioxidant responses to Al along the 0–25 mm root tip of two wheat genotypes differing in Al tolerance were analyzed. Under Al stress, the lowest root elongation was in the 0–5 mm root tip, and more severe inhibition was observed in Al-sensitive genotype than Al-tolerant genotype. The highest increase of Al and hydrogen peroxide (H2O2) was in the 0–5 mm zone, with the most pronounced increase of malondialdehyde content and Evans blue uptake after Al exposure, especially in Al-sensitive genotype. The activities of superoxides dismutase (SOD), ascrobate peroxidase (APX), catalase (CAT) and peroxidase (POD) and levels of antioxidants (ascorbic acid, reduced glutathione, dehydroascorbate, glutathione disulfide) were significantly increased along the root tip under Al stress, with the 0–5 mm region again being the most active zone. In the same zone, the activities of CAT, APX and contents of antioxidants were higher in Al-tolerant genotype while SOD and POD activities were lower. Our results indicate that Al-induced changes in H2O2 production and antioxidative system in root tip are regulated in a spatially-specific manner, suggesting that this response may play an important role in wheat adaptation to Al toxicity.

Vegetative propagation by cuttings is a very popular method. However, blueberry propagation using cuttings is still a main factor limiting its expansion because its results can vary according to the blueberry cultivar and environmental factors. This study aimed to evaluate the rooting abilities of hardwood cuttings for six blueberry cultivars (O’Neal, Misty, Diana, Biloxi, Bluebeauty, and Coville) using three different exogenous indole-butyric acid (IBA) concentrations (1000, 2000, and 3000 ppm), and to determine if the cutting position (basal, central, apical) affects rooting performance. A control treatment (0 ppm IBA) was also performed. After 90 days of each treatment, rooting percentage, average root length, and average root number per cutting were assessed and used to calculate rooting index, which is a measure of rooting ability. The rooting percentages of hardwood cuttings differed largely among cultivars and were highest for ‘Bluebeauty’ (68.55%), followed by ‘Biloxi’ (68.01%). The rooting index values of these two cultivars (33.59 and 35.18, respectively) were significantly higher than those of the other four cultivars. The rooting response of blueberry hardwood cuttings to IBA concentrations was quadratic, and 1000 and 2000 ppm IBA were sufficient to express the maximum rooting percentage in most cultivars. The rooting abilities of basal, central, and apical cuttings were similar with treatments with high IBA concentrations. The effects of the cultivar, IBA concentration, and interaction between them on rooting percentage, average root length, and average root number were significant; however, the effects of the cutting position on the rooting percentage and average root length were not. This suggested that the rooting abilities of blueberry hardwood cuttings were significantly influenced by the cultivar and IBA concentration rather than by the cutting position.

Semiconductor nanowires are the ideal building blocks to construct various thin-film electronic and optoelectronic devices, the performance of which is largely determined by their ensemble geometry and surface chemistry in addition to the chemical composition. Here, we report the large-scale and oriented assembly of CdSe nanowires on the basis of a light-induced assembly approach under an external electric field. To further increase the electrical conductivity of nanowire films, the original surface-capping organic ligands are exchanged with small ionic species through a solid-state ligand-exchange process. The resulting surface-modified CdSe nanowire films exhibit markedly enhanced photoresponse properties including high on/off ratios and fast response. This work establishes a simple yet scalable method to fabricate aligned nanowire films with a desired surface chemistry, which can be broadly used in various electronic and optoelectronic devices.

Ternary alloyed semiconductor nanostructures have attracted increasingly greater attention due to their unique physiochemical properties that may not be available in the parent binary systems. In this work, we report the solution–liquid–solid (SLS) growth of colloidal, uniform ZnSexTe1–x nanowires (NWs), the composition of which can be tuned over a wide range by manipulating the growth rate of multicomponent constituents. Two sets of ZnSexTe1–x NWs with high compositional homogeneities are synthesized by using zinc stearate (Zn(St)2) and diethyl zinc (Zn(Et)2) as the Zn precursor, respectively. The resultant NWs are systematically characterized with respect to the structure, composition, and optical band gap, and on the basis of these, the composition dependence of band gaps is extracted. Both sets of colloidal ZnSexTe1–x NWs are found to exhibit strong band bowing with the band gap minimum occurring at x = 0.30, which is consistent with the previously reported results based on ZnSexTe1–x bulk materials a...

Pedestrian Re-identification faces many difficulties in training of supervised model because of limited number of labeled data of surveillance videos. Besides, applications of pedestrian re-identification in pedestrian retrieving and criminal tracking are limited because of the lack of semantic representation. In this paper, a data-driven pedestrian re-identification model based on hierarchical semantic representation is proposed, this model extracting essential features with unsupervised deep learning model and enhancing the semantic representation of features with hierarchical mid-level attributes. Firstly, CNNs, well-trained with the training process of CAEs, is used to extract features of horizontal blocks segmented from unlabeled pedestrian images. Then, these features are input into corresponding attribute classifiers to judge whether the pedestrian has the attributes. Lastly, with a table of ‘attributes-classes mapping relations’, final result can be calculated. Our method is proved to significantly outperform the state of the art on the VIPeR and i-LIDS data set in the aspects of accuracy and semanteme.

The physicochemical properties and biomedical applications of Fe3O4 microspheres are strongly dependent on their size. Herein we report a new approach to tune the size of carboxyl-functionalized Fe3O4 microspheres via a polyol process. The diameter of Fe3O4 microspheres can be tuned in the range of 300–900 nm by simply changing the reactant mixing process while keeping other conditions constant. Mild mixing process produces Fe3O4 microspheres with large size while vigorous mixing process produces small microspheres. The mixing process does not significantly change the composition, surface and magnetic properties of the Fe3O4 microspheres. A possible mechanism for the influence of mixing process on the size of Fe3O4 microspheres is also proposed in this paper.

The transverse relaxation rate (1/T2) of aqueous suspensions of magnetite nanocrystal clusters with a SiO2 shell of different thicknesses has been studied experimentally. With the increase of the shell thickness, 1/T2 decreases slightly due to the aggregation of clusters during coating process. In T2 measurement, the waiting time dependence decreases when the shell gets thicker, because of the decreased magnetic attractive energy, particle number concentration and diffusion coefficient of magnetite nanocrystal clusters with a thicker SiO2 shell. These experimental results, supporting the relaxation theory and computer simulations, may promote future development of magnetic contrast agents.

All-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) are emerging as an important class of semiconductor materials with superior photophysical properties and wide potential applications in optoelectronic devices. So far, only a few studies have been conducted to control the shape and geometry of CsPbX3 NCs. Here we report a general approach to directly synthesize two-dimensional (2D) CsPbX3 perovskite and mixed perovskite nanosheets with uniform and ultrathin thicknesses down to a few monolayers. The key to the high-yield synthesis of perovskite nanosheets is the development of a new Cs-oleate precursor. The as-synthesized CsPbX3 nanosheets exhibit bright photoluminescence with broad wavelength tunability by composition modulation. The excellent optoelectronic properties of CsPbX3 nanosheets combined with their unique 2D geometry and large lateral dimensions make them ideal building blocks for building functional devices. To demonstrate their potential applications in optoelectronics, photodetectors based on CsPbBr3 nanosheets are fabricated, which exhibit high on/off ratios with a fast response time.

The transverse relaxation rate 1 / T 2 of several batches of water suspensions of magnetite nanoclusters of average effective size 2 R eff between 37 and 475 nm has been studied experimentally as a function of volume fraction fv, inter-echo time 2 τ CP , and waiting time tw. It is found that T2 for suspensions with 2 R eff around or larger than 80 nm increases significantly with tw, and the tw dependence is enhanced by decreasing τ CP . The initial relative T2 increase rate is roughly proportional to fv for each batch of suspensions at a fixed value of τ CP and roughly proportional to R eff − 1 at given values of τ CP and fv. After extrapolating tw to 0, 1 / T 2 ∝ f v λ ( λ ≈ 1 ) occurs for all batches of suspensions at given value of τ CP , where λ increases slightly with increasing τ CP for each batch of suspension. 1 / T 2 ∝ τ CP κ ( κ > 0 ) occurs roughly for all suspensions, where κ increases slightly with increasing fv and greatly with increasing 2 R eff . Such fv and τ CP dependences are qualitatively predicted by a well accepted formula for the echo-refocusing limit. However, the experimental results for the batch with largest 2 R eff , which is well located in the echo-limiting regime, agree better with a simplified formula. The theoretical static dephasing upper limit of 1/T2 may be reached for suspensions of 2 R eff around 100 nm at τ CP = 3.2 ms , and the experimental echo-limiting regime starts at a smaller 2 R eff than the simulated one. All these phenomena have been explained based on existing knowledge, but further experimental and theoretical studies are necessary to fully understand them.

Limited number of labeled data of surveillance video causes the training of supervised model for pedestrian re-identification to be a difficult task. Besides, applications of pedestrian re-identification in pedestrian retrieving and criminal tracking are limited because of the lack of semantic representation. In this paper, a data-driven pedestrian re-identification model based on hierarchical semantic representation is proposed, extracting essential features with unsupervised deep learning model and enhancing the semantic representation of features with hierarchical mid-level ‘attributes’. Firstly, CNNs, well-trained with the training process of CAEs, is used to extract features of horizontal blocks segmented from unlabeled pedestrian images. Then, these features are input into corresponding attribute classifiers to judge whether the pedestrian has the attributes. Lastly, with a table of ‘attributes-classes mapping relations’, final result can be calculated. Under the premise of improving the accuracy of attribute classifier, our qualitative results show its clear advantages over the CHUK02, VIPeR, and i-LIDS data set. Our proposed method is proved to effectively solve the problem of dependency on labeled data and lack of semantic expression, and it also significantly outperforms the state-of-the-art in terms of accuracy and semanteme.

Magnetic iron oxide particles are widely used as contrast agents to improve the sensitivity of magnetic resonance imaging (MRI). Their efficiency in MRI is usually quantified by transverse relaxivity (r(2)) in solution. Herein, we synthesized a series of magnetite nanocrystal clusters (MNCs) with ultra-high transverse relaxivity by a polyol process and studied the relationship between r(2) and size of the MNCs. The sizes of MNCs can be tuned over a wide range from 13 to 179 nm. The r(2) of MNC suspensions as a function of the size of the cluster was analyzed and compared with a theoretical model. We found that MNCs of 64 nm had an r(2) value of 650 mM(-1) s(-1), which was more than three times that of the commercial contrast agent and was among the highest reported for iron oxide materials. Compared with the theoretical model, the r(2) value of the MNC suspension is approximately 0.93 of the theoretical prediction. Imaging of the MNC suspensions was performed in a clinical 1.5 T MRI instrument and a comparison was made between MNCs and commercial contrast agents. MRI indicated that the decrease of signal intensity induced by MNCs was in proportion to the r(2) value, which was in accordance with theoretical predictions. These results demonstrate that MNCs with ultra-high transverse relaxivity and tunable size are promising candidates for molecular imaging and clinical diagnosis in MRI.

Teaching and learning the theory of relation normalization in a database course is a nontrivial work. Although this theory and the related concepts and algorithms have been clearly stated in authoritative texts, suitable CAIs have not been found to our best knowledge. This paper reports a CAI tool, RDBNorm, the authors designed and implemented to facilitate both teachers' classroom teaching and students' home practicing of the theory of relation normalization. RDBNorm demonstrates relation normalization associated algorithms step by step to make them easy to understand, as well as a theory tutorial presenting the key points of the theory.

A series of magnetic iron oxide nanoparticle clusters and porous nanoparticles with high magnetization are synthesized using the polyols with different reductive abilities. To investigate the morphology evolution in a polyol process, HRTEM is used to study the products. When ethylene glycol is used as the solvent, iron oxide nanoparticles form and then self-assemble into compact nanoparticle clusters (ca. 300 nm) through oriented attachment growth with a few misarranged nanoparticles in the clusters. At last these clusters develop into flower-like clusters with single crystal-like diffraction. When 1,2-propylene glycol is employed as the solvent, iron oxide nanoparticles quickly self-assemble into nanoparticle clusters (ca. 50 nm) with many misarrangements. As the reaction time extends, these clusters collapse and split into porous nanoparticles. According to the morphology evolution of iron oxide nanoparticles in different polyols, we propose our reasonable supposition on the whole process. These findings may help to understand the role of the polyol as solvent and obtain the novel secondary structures of nanoparticles in a polyol process.

Silica coated, PEI and citric acid hybrid superparamagnetic magnetite nanocrystal clusters (SMNC) were synthesized using either a mini-emulsion/sol–gel method or a polyol technique. After careful characterization of the size, structure, composition, and magnetic properties, the as-synthesized SMNC were used for cell labeling while the MR detection sensitivity of cells labeled with silica SMNC was performed with a 3 T whole body MR scanner. TEM investigations revealed that the sizes of the SMNC were about 200 nm and the SMNC mainly consisted of magnetite nanoparticles imbedded in a PEI, citric acid or polystyrene scaffold. Silica and citric acid SMNC were highly negatively charged and PEI SMNC were positively charged. Relaxometry measurements revealed that these SMNC possessed a very high MR sensitivity (silica SMNC: r2 = 299 s −1 mM −1 ,P EI SMNC:r2 = 124 s −1 mM −1 ), especially for the citric acid SMNC (r2 = 360 s −1 mM −1 ). Furthermore, when used for cell (RAW264.7 cells) labeling, the SMNC had no adverse effect on cell viability, and the cell uptake of the SMNC show a dose- and time-dependent feature. MR imaging of cells labeled with silica SMNC indicated that cells with a concentration as low as 10 × 10 3 cells ml −1 could be detected with a 3 T MRI scanner. Our study demonstrated that superparamagnetic magnetite nanocrystal clusters are a sensitive tool for cell imaging. (Some figures in this article are in colour only in the electronic version)