A novel method to prepare water-soluble cellulose-based fluorescent probes for highly sensitive and selective detection and removal of Hg2+/Hg22+ ions.

Improving the water solubility of natural product cellulose and using it to treat heavy metal ions is very important. In this work, cellulose-based fluorescent probes containing BODIPY fluorophore were synthesized by simple chemical method, which realized the selective recognition and removal of Hg2+/Hg22+ ions in an aqueous system. Firstly, fluorescent small molecule (BOK-NH2) bearing -NH2 group was synthesized through Knoevenagel condensation reaction between BO-NH2 and cinnamaldehyde. Secondly, via the etherification of -OH on the cellulose, substituents bearing -C ≡ CH groups with different lengths at the end are grafted on the cellulose. Finally, cellulose-based probes (P1, P2, and P3) were prepared by amino-yne click reaction. The solubility of cellulose is improved greatly, especially the cellulose derivative with branched long chains has excellent solubility in water (P3). Benefiting from the improved solubility, P3 could be processed into solutions, films, hydrogels, and powders. Upon the addition of Hg2+/Hg22+ ions, the fluorescence intensity enhanced, which are "turn-on" probes. At the same time, the probes could be utilized as efficient adsorbents for Hg2+/Hg22+ ions. The removal efficiency of P3 for Hg2+/Hg22+ is 79.7 %/82.1 %, and the adsorption capacity is 159.4 mg·g-1/164.2 mg·g-1. These cellulose-based probes are expected to be employed in the treatment of polluted environments.

Diffusion kurtosis imaging and MRI-detected extramural venous invasion in rectal cancer: correlation with clinicopathological prognostic factors.

OBJECTIVE: To investigate the prognostic value of the diffusion kurtosis imaging (DKI)-derived parameters D value, K value, diffusion-weighted imaging (DWI) parameter apparent diffusion coefficient (ADC) value, and magnetic resonance imaging (MRI)-detected extramural venous invasion (EMVI) (mrEMVI) in rectal cancer patients. METHODS: Forty patients who underwent MRI for rectal cancer were retrospectively evaluated. DKI-derived parameters D and K were measured using the Medical Imaging Interaction Toolkit. Conventional ADC values were measured from the corresponding DWI images. An experienced radiologist evaluated the mrEMVI status on MR images using the mrEMVI scoring system. An independent sample t-test or analysis of variance was used to analyze and compare the measurement data. The x2 test or Fisher exact test was used for categorical variables. Receiver operating characteristic curves were used to assess the diagnostic performance of these parameters. RESULTS: Among the 40 patients, MRI showed positive EMVI in 15 patients and negative EMVI in 25 patients. Positive mrEMVI status was associated with age, positive circumferential resection margin, pT-stage, lymphovascular invasion (LVI), distant metastasis, and serum carcinoembryonic antigen (CEA) level (P = 0.004-0.036). The dispersion coefficient (D) values and ADC values were significantly higher in the mucinous adenocarcinoma (MC) group than in the common adenocarcinoma (AC) group (P = 0.001), while kurtosis coefficient (K) values were lower in the MC group than in the AC group (P = 0.022). D values were significantly higher in the KRAS-mutated group than in the wild-type group (P < 0.05), whereas K values were lower in the KRAS-mutated group than in the wild-type group (P < 0.05). All three parameters (D, K, and ADC values) showed good diagnostic performance for discriminating MC from AC. Both the D and K values showed certain diagnostic performance for discriminating KRAS mutation. CONCLUSION: DKI-derived parameters, conventional ADC values, and mrEMVI are associated with different histopathological prognostic factors. All DKI-derived parameters and conventional ADC values may distinguish MC from AC. DKI-derived parameters may also be used to discriminate KRAS mutation.

Influence of job environment on the online teaching anxiety of college teachers in the online teaching context: The mediating role of subjective well-being.

Background: Online education has been conducted widely in higher education in recent years. While online teaching brings many opportunities, it also poses numerous challenges and issues. This is especially true for college teachers, for whom teaching is considered to be a profession with a high level of burnout and anxiety. The large-scale application of online teaching methods has put teachers in an even more challenging context, which may lead to teaching anxiety affecting their mental health. In online teaching contexts, the question of what factors affect college teachers' online teaching anxiety is worth exploring to help reduce their online teaching anxiety so as to promote their work performance. In this study, therefore, we conducted a survey of college teachers to develop a model of job environment (job demands and job resources), subjective well-being, and online teaching anxiety, and to explore the influences of job environment and subjective well-being on their online teaching anxiety, as well as the mediating effects of subjective well-being between job environments and online teaching anxiety. Method: Of the 1,060 college teachers who participated, 524 were male (49.4%) and 536 were female (50.6%). An online questionnaire was sent to the teachers in January, 2022. Online teaching anxiety, subjective well-being, and job environment scales were adapted and developed. Descriptive analysis, reliability and validity analysis, and structural equation modelling were used to analyse the collected data. Results: The study model showed an adequate fit (χ2 = 440.983, RMSEA = 0.070, GFI = 0.942, AGFI = 0.914, NFI = 0.949, and CFI = 0.956), confirming the relationships of job demands and online teaching anxiety (ß = 0.310, p < 0.001), job resources and online teaching anxiety (ß = - 0.086, p < 0.01), job demands and subjective well-being (ß = - 0.411, p < 0.001), job resources and subjective well-being (ß = 0.204, p < 0.001), and subjective well-being and online teaching anxiety (ß = - 0.435, p < 0.001). Meanwhile, the results also proved the effects of the mediating role of subjective well-being between job demands (95% CI = [- 0.138, - 0.225]), job resources (95% CI = [- 0.119, - 0.064]), and online teaching anxiety. The model accounted for 33.8% (f 2 = 0.401) of online teaching anxiety. Conclusion: The results of this study indicated that it is important to reduce job demands and increase job resources to alleviate college teachers' online teaching anxiety to maintain good mental health; while maintaining a high level of college teachers' subjective well-being is also helpful for promoting their work performance. Furthermore, the indirect effects of job demands and job resources on online teaching anxiety mediated by college teachers' subjective well-being were also significant.

White Matter Network Disruption Is Associated With Melancholic Features in Major Depressive Disorder.

Background: The efficacy and prognosis of major depressive disorder (MDD) are limited by its heterogeneity. MDD with melancholic features is an important subtype of MDD. The present study aimed to reveal the white matter (WM) network changes in melancholic depression. Materials and Methods: Twenty-three first-onset, untreated melancholic MDD, 59 non-melancholic MDD patients and 63 health controls underwent diffusion tensor imaging (DTI) scans. WM network analysis based on graph theory and support vector machine (SVM) were used for image data analysis. Results: Compared with HC, small-worldness was reduced and abnormal node attributes were in the right orbital inferior frontal gyrus, left orbital superior frontal gyrus, right caudate nucleus, right orbital superior frontal gyrus, right orbital middle frontal gyrus, left rectus gyrus, and left median cingulate and paracingulate gyrus of MDD patients. Compared with non-melancholic MDD, small-worldness was reduced and abnormal node attributes were in right orbital inferior frontal gyrus, left orbital superior frontal gyrus and right caudate nucleus of melancholic MDD. For correlation analysis, the 7th item score of the HRSD-17 (work and interest) was positively associated with increased node betweenness centrality (aBC) values in right orbital inferior frontal gyrus, while negatively associated with the decreased aBC in left orbital superior frontal gyrus. SVM analysis results showed that abnormal aBC in right orbital inferior frontal gyrus and left orbital superior frontal gyrus showed the highest accuracy of 81.0% (69/83), the sensitivity of 66.3%, and specificity of 85.2% for discriminating MDD patients with or without melancholic features. Conclusion: There is a significant difference in WM network changes between MDD patients with and without melancholic features.

Promoting Pre-service Teacher Students' Learning Engagement: Design-Based Research in a Flipped Classroom.

Students' learning engagement is recognized as one of the main components of effective instruction and a necessary prerequisite for learning, but students' learning engagement in flipped classroom poses some pedagogical challenges. This study aimed to promote students' learning engagement via the flipped classroom approach. Design-based research (DBR) was adopted in this study to conduct an experiment involving three iterations in a Modern Educational Technology (MET) course in a Chinese university. The participants included 36 third-year pre-service teacher undergraduates. Classroom observations and a learning engagement questionnaire were used to measure the effectiveness of the flipped instruction in terms of students' learning engagement. Data analysis applied descriptive statistics, ANOVA, and paired samples t tests. The results showed that after three rounds of iterative experiments, students' learning engagement (behavioral, cognitive, and emotional) significantly improved. Several principles are provided as guidelines for instructors to implement flipped classroom approach to promote students' learning engagement.

Disrupted default mode network and executive control network are associated with depression severity on structural network.

OBJECTIVE: Major depressive disorder (MDD) is a psychiatric disorder with a relatively limited response to treatment. It is necessary to better understand the neuroanatomical mechanisms of structural networks. METHODS: The current study recruited 181 first-onset, untreated adult MDD patients: slight MDD (SD, N = 23), moderate MDD (MD, N = 77), Heavy MDD (HD, N = 81) groups; along with a healthy control group (HC, N = 81) with matched general clinical data. FreeSurfer was used to preprocess T1 images for gray matter volume (GMV), and the default mode network (DMN) and the execution control network (ECN) were analyzed by structural covariance network (SCN). RESULTS: Present study found that the GMV of brain regions reduced with the severity of the disease. Specifically, the GMV of the left anterior cingulate gyrus (ACC.L) is negatively correlated with MDD severity. In addition, the SCN connectivity of the whole-brain network increases with the increase of severity in MDD. ACC.L is a key brain region with increased connectivity between the left orbitofrontal in DMN and between the right orbitofrontal in ECN, which leads to damage to the balance of neural circuits. CONCLUSIONS: Patients with smaller GMV of ACC.L are more likely to develop severe MDD, and as a key region in both networks which have distinct structural network models in DMN and ECN. MDD patients with different severity have different neuroimaging changes in DMN and ECN.

Performance Evaluation and Comparison between Direct and Chemical-Assisted Picosecond Laser Micro-Trepanning of Single Crystalline Silicon.

The fabrication of micro-holes in silicon substrates that have a proper taper, higher depth-to-diameter ratio, and better surface quality has been attracting intense interest for a long time due to its importance in the semiconductor and MEMS (Micro-Electro-Mechanical System) industry. In this paper, an experimental investigation of the machining performance of the direct and chemical-assisted picosecond laser trepanning of single crystalline silicon is conducted, with a view to assess the two machining methods. The relevant parameters affecting the trepanning process are considered, employing the orthogonal experimental design scheme. It is found that the direct laser trepanning results are associated with evident thermal defects, while the chemical-assisted method is capable of machining micro-holes with negligible thermal damage. Range analysis is then carried out, and the effects of the processing parameters on the hole characteristics are amply discussed to obtain the recommended parameters. Finally, the material removal mechanisms that are involved in the two machining methods are adequately analyzed. For the chemical-assisted trepanning case, the enhanced material removal rate may be attributed to the serious mechanical effects caused by the liquid-confined plasma and cavitation bubbles, and the chemical etching effect provided by NaOH solution.

Are ADC values of readout-segmented echo-planar diffusion-weighted imaging (RESOLVE) correlated with pathological prognostic factors in rectal adenocarcinoma?

BACKGROUND: Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values as imaging biomarkers of rectal cancer are currently a hot research spot. The use of ADC values for preoperative judgment of pathological features in rectal cancer has been generally accepted. The image quality evaluation of conventional diffusion is severe deformation, and the measurement of ADC values can easily lead to bias. Readout-segmented echo-planar diffusion-weighted imaging (RESOLVE) provides high signal-to-noise ratio images and significantly reduces distortions caused by magnetosensitive effects. The purpose of this study was to explore the correlations between ADC values of RESOLVE and pathological prognostic factors in rectal adenocarcinoma. METHODS: We collected pathological data of 89 patients with pathologically confirmed rectal adenocarcinoma who directly underwent surgical resection without receiving adjuvant therapy. The patients were grouped according to the pathologic type, gross classification, degree of differentiation, TN stage, and immunohistochemical expression of epidermal growth factor receptor (EGFR). RESULTS: RESOLVE ADC values of rectal cancer were measured at b = 800, and correlations between the RESOLVE ADC values obtained in different groups were analysed. We found that RESOLVE ADC values in the ulcer-type group were significantly higher than those in the eminence-type group. CONCLUSION: RESOLVE ADC values in different pathologic types of rectal cancer were significantly different. RESOLVE ADC values in the EGFR-positive group were significantly lower than those in the EGFR-negative group. There was no significant difference in RESOLVE ADC values between different degrees of pathologic differentiation, TN stages, and positive or negative lymph nodes. The quantitative description of RESOLVE ADC values could be used to assess the biological behaviour of rectal adenocarcinoma.

Preparation of brookite TiO2 nanoparticles with small sizes and the improved photovoltaic performance of brookite-based dye-sensitized solar cells.

Brookite TiO2 nanoparticles with small sizes (hereafter denoted as BTP particles) were synthesized through the hydrothermal treatment of TiCl4 solution with Pb(NO3)2 as an additive. The obtained BTP particles have a large specific surface area (∼122.2 m2 g-1) and relatively uniform particle sizes (∼10 nm) with the coexistence of a small quantity of nanorods with a length of ∼100 nm. When used as a photoanode material for dye-sensitized solar cells (DSSCs), the BTP particles show a much higher dye-loading content than the brookite TiO2 quasi nanocubes (denoted as BTN particles) with a mean size of ∼50 nm and a specific surface area of ∼34.2 m2 g-1 that were prepared through a similar hydrothermal process but without the addition of Pb(NO3)2. The fabricated BTP film-based solar cell with an optimized film thickness gives a conversion efficiency up to 6.36% with a 74% improvement when compared to the BTN film-based one (3.65%) under AM 1.5G one sun irradiation, while the corresponding bilayer brookite-based solar cell by using brookite TiO2 submicrometer particles as an overlayer of the BTP film displays a significantly enhanced efficiency of 7.64%. Both of them exceed the current record (5.97%) for the conversion efficiency of pure brookite-based DSSCs reported in the literature. The present results not only demonstrate a really simple synthesis of brookite TiO2 nanoparticles with both high phase purity and a large surface area, but also offer an efficient approach to improve the photovoltaic performance of brookite-based solar cells by offsetting brookite's inherent shortages such as lower dye-loading and poor conductivity as compared to anatase.

Determination of gamithromycin in an injection by ultra-performance liquid chromatography-tandem quadrupole-time-of-flight mass spectrometry.

In this study, a sensitive and precise method was developed for the determination of gamithromycin in an injection using ultra-performance liquid chromatography-tandem quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS) and the results were compared with a similar analysis for the ion fragments of gamithromycin in MS/ MS. The sample was dissolved in methanol then filtered and separated on a C18 column using acetonitrile-0.1% formic acid (containing 2 mmol/L ammonium acetate) as the mobile phase. The flow rate was 0.4 mL/min and the column temperature was 40 °C. The mass spectrometry conditions were electrospray ionization (ESI) operated in positive ion full scan mode and quantified using external calibration. Subsequently, ion fragments of the MS/MS were compared and analyzed. The linear range was 10 ∼ 200 µg/L with a correlation coefficient of 0.9992. The limit of detection (LOD) was 0.77 µg/L and the limit of quantitation (LOQ) was 2.55 µg/L. The average recoveries of the intra-assay were 98.8%-105.6% with a relative standard deviation ranging from 1.79% to 2.38% and the inter-assay were 89.3%-110.7% with a relative standard deviation ranging from 4.93% to 6.27%. After the comparative analysis of the fragments with a Molecular Structure Correlator, the score of the total matching degree reached 83.19 and the scores of each ion fragment matching degree were all greater than 90, which supplied the basis for the confirmation of gamithromycin. The results indicated that the method was simple, sensitive and precise and could be applied in the determination of gamithromycin in real samples.