Self-Healable, Malleable, Ecofriendly Recyclable and Robust Polyimine Thermosets Derived from Trifluoromethyl Diphenoxybenzene Backbones.

Dynamic covalent chemistry opens up great opportunities for a sustainable society by producing reprocessable networks of polymers and even thermosets. However, achieving the closed-loop recycling of polymers with high performance remains a grand challenge. The introduction of aromatic monomers and fluorine into covalent adaptable networks is an attractive method to tackle this challenge. Therefore, we present a facile and universal strategy to focus on the design and applications of polyimine vitrimers containing trifluoromethyl diphenoxybenzene backbones in applications of dynamic covalent polymers. In this study, fluorine-containing polyimine vitrimer networks (FPIVs) were fabricated, and the results revealed that the FPIVs not only exhibited good self-healability, malleability and processability without the aid of any catalyst, but also possessed decent mechanical strength, superior toughness and thermal stability. We hope that this work could provide a novel pathway for the design of high-performance polyimine vitrimers by recycling of plastic wastes.

Synergistic Effect and Electrical Properties of Microporous Liquid Metal/Carbon Nanotube Polymer Sponge.

Sensing sponge materials with light weight, high elasticity, and electrical sensing properties are in enormous demand in electronic fields, but there is an imminent need to develop a scalable and facile method for the manufacture of the sensing material. Herein, an efficient in situ polymerization and convenient preparation process is reported to manufacture the microporous liquid metal/carbon nanotube-polysulfide rubber (LM/CNT-PSR) sponges with excellent mechanical and electrical properties, based on fluidic LMs and rigid CNTs with unique synergistic effect for sponge composites. Excellent mechanical properties of LM/CNT-PSR sponges, such as low density, excellent elasticity, remarkable mechanical recoverability, and self-healing property, are endowed by the interconnected microporous structure of sponge and flexible polysulfide rubber matrix with disulfide bonds. In addition, the synergistic effect of LMs and CNTs leads to excellent conductivity and unique electrical sensing property under mechanical pressure. Microporous LM/CNT-PSR sponges with high performance and simple fabrication process are promising sensing materials for various electronic devices, such as human motion monitoring, and weighing sensing.

A safe area for sternal puncture in children: an MSCT study based on sternal development.

PURPOSE: Multislice spiral CT (MSCT) was used to investigate the anatomical characteristics of sternal development, and to provide anatomical basis for sternal puncture in children. METHODS: We retrospectively analyzed the thoracic MSCT data of 600 children who received thoracic MSCT from January to June 2020 with their age ranging from 1 month to 19 years. The distribution of sternal ossification centers and adjacent tissues and organs was observed. Subcutaneous soft tissue thickness and the distance between the skin and the posterior margin of the sternum were measured in the central areas of sternal manubrium and mesosternum (segments I and II), and the correlation between the two was calculated using linear correlation. RESULTS: A total of 600 patients were enrolled, the mean age was 9.87 years and the standard deviation was 8.28 years. The sternal manubrium and ossification centers at the I and II segments of the mesosternum were visible in all cases (100%). There was no ossification in segment III of the mesosternum in 15 cases (2.5%), including 12 cases (80%) adjacent to the posterior pericardium and 7 cases (46.7%) of lung tissue. There were 274 cases (45.7%) of segment IV without ossification, including 204 cases (74.5%) of adjacent pericardium and 95 cases (32.8%) of lung tissue. The xiphoid process was not ossified in 258 cases (43%), including 190 cases (73.6%) adjacent to the pericardium and 97 cases (37.6%) adjacent to the lung tissue. Correspondingly, the thickness of subcutaneous soft tissue of the sternal manubrium and the central region of the I and II segments of the mesosternum had a low positive correlation with age (P < 0.001), the distance between the skin and the posterior margin of the sternum showed a moderate positive correlation with age (P < 0.001), and the distance between the skin and the posterior margin of the sternum showed a high positive correlation with the thickness of subcutaneous soft tissue (P < 0.001). CONCLUSIONS: Nonossification of the sternal ossification center usually occurs below segment III of the mesosternum and is usually adjacent to heart and lung tissue. Pediatric sternal puncture should be performed at the sternal manubrium and the mesosternum of segments I and II. However, attention should be paid to the space between multiple ossification centers. The thickness of subcutaneous soft tissue is a critical factor that determines the depth of the puncture.

The Role of Teacher-Student Interpersonal Relations in Flipped Learning on Student Engagement.

Education, in essence, is an interactive activity in which teacher and student interactions construct a learning path to raise knowledge. However, it is evident that this learning path is not merely cognitive. Thus, the role of interpersonal relationships should not be taken for granted. Teacher-student relationships are among the salient factors in effective teaching. Factors such as these trigger achievement, motivation, and engagement in students (Martin and Dowson, 2009), with student engagement in particular seeming like the keystone for educational achievement. One relative innovation that promotes student engagement and undertakes more effective learning and deeper knowledge of the materials is flipped learning (Kim, 2017). This theoretical review article was written to enlighten scholars, teachers, and learners with key concepts in interpersonal relations and their roles on student engagement in the context of flipped learning. In this study, some pedagogical implications were presented with the prospect of edifying the practice of teachers, students, and syllabus designers.

Identification of the first Alu-mediated gross deletion involving the BCKDHA gene in a compound heterozygous patient with maple syrup urine disease.

AIMS: To investigate a family with clinical symptoms of maple syrup urine disease and reveal a genetic cause underlying this disease. METHODS: Targeted capture sequencing was used to screen for mutations in the patient. Real-Time PCR was carried out to perform exon 1, 5, 9 CNV analysis of samples from the patient's father, mother and sister. Whole genome sequencing was performed to map the approximate location of the break points of the gross deletion. Long-range PCR and Sanger sequencing were performed to identify the length of the deletion and to locate the break points. RESULTS: The patient is a compound heterozygous mutation including a small deletion mutation (c.1227_1229del chr19: 41930402) and a gross novel deletion including exon1-9 in BCKDHA. The junction site of the gross deletion was localized within a microhomologous sequence in two Alu elements. CONCLUSIONS: This study is the first time report on rearrangement sequences in BCKDHA mediated by Alu element, which resulted in MSUD. Our results may also offer new insights into the formation and pathogenicity of MSUD, and may be useful to genetic counseling and genetic testing.

[Allelopathy of rape on seed germination and seedling growth of three crops]. / 油菜对3种作物种子萌发和幼苗生长的化感作用.

Rape is an important green manure crop in China. It could increase soil fertility, but might have allelopathic effect on subsequent crops. We examined the effects of rape water-extract (at 0.025, 0.05 and 0.1 g·mL-1 concentrations) on seed germination, seedling growth, physiology and biochemistry of three crops including oat (Avena sativa), corn (Zea mays), and sunflower (Helianthus annuus). The results showed that water extract of rape did not affect seed germination rate of three crops. Oat had a trend of "low promotion and high inhibition", while sunflower had a trend of inhibition. High concentration of rape water extract inhibited root and stem length of oat seedling, corn seedling stem length and sunflower seedling root length, while low concentration treatment promoted root and stem length of corn seedling. The highest protein contents in oats and sunflower presented at the treatment of 0.05 g·mL-1, and that of corn at the treatment of 0.025 g·mL-1, which were significantly higher than that of control. The proline contents in sunflower decreased significantly in different treatments, while the proline content of corn was significantly higher than that of control at 0.05 g·mL-1. POD activity of corn was at a maximum at 0.05 g·mL-1, and that of sunflower was at 0.025 g·mL-1, which were significantly higher than control. There was no significant difference between control and other concentration treatments. The SOD activity of oat was significantly decreased at 0.025 g·mL-1. There was no significant difference in CAT activity between the three crops and the control. The MDA content in sunflower seedlings increased significantly at 0.1 g·mL-1, while that in corn seedlings was significantly lower than control. Our results indicated that the allelopathic inhibitory effect of rape water extract was the strongest on sunflower, followed by corn and oat.

Controlled in vitro degradation behavior of highly oriented long-chain-branched poly(lactic acid) produced by solid-phase die drawing.

Highly oriented long-chain-branched poly(lactic acid) (LCB-PLA) was fabricated through solid-phase die drawing technology, and the in vitro degradation behavior of the oriented samples in phosphate-buffered saline (PBS) was studied. During degradation, the weight retention and molecular weight for both PLA and LCB-PLA increased with the increase of draw ratio. Moreover, the degradation autocatalytic effect was delayed, and the deterioration of mechanical strength was reduced by orientation, which was beneficial for controlling the degradation degree and decay rate of strength for PLA as bone fixation materials. The influence mechanism of orientation on the in vitro degradation of PLA was explored. The degradation of PLA in PBS was ascribed to the hydrolytic degradation of ester bonds on the molecular chain. By orientation, a dense microfibrillar crystalline structure formed both on the surface and inside of PLA samples, limiting the diffusion and absorption of PBS molecules into the PLA matrix effectively, inhibiting the hydrolytic degradation of ester bonds, and thus delaying the deterioration of mechanical properties of PLA. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.

Effects of irradiation on radioresistance, HOTAIR and epithelial-mesenchymal transition/cancer stem cell marker expression in esophageal squamous cell carcinoma.

Radiotherapy is a common therapeutic strategy used to treat esophageal squamous cell carcinoma (ESCC). However, tumor cells often develop radioresistance, thereby reducing treatment efficacy. Here, we aimed to identify the mechanisms through which ESCC cells develop radioresistance and identify associated biomarkers. Eca109 cells were exposed to repeated radiation at 2 Gy/fraction for a total dose of 60 Gy (Eca109R60/2Gy cells). MTT and colony formation assays were performed to measure cell proliferation and compare the radiation biology parameters of Eca109 and Eca109R60/2Gy cells. Cell cycle distributions and apoptosis were assessed by flow cytometry. Reverse transcription-quantitative polymerase chain reaction and western blotting were employed to analyze the expression of HOX transcript antisense RNA (HOTAIR), in addition to biomarkers of the epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). Eca109R60/2Gy cells exhibited increased cell proliferation and clone formation, with significantly higher radiobiological parameters compared with the parental Eca109 cells. The Eca109R60/2Gy cells also exhibited significantly decreased accumulation in G2 phase and increased accumulation in S phase. Additionally, the apoptosis rate was significantly lower in Eca109R60/2Gy cells than in parental Eca109 cells. Finally, HOTAIR expression levels and SNAI1 and ß-catenin mRNA and protein expression levels were significantly higher, whereas E-cadherin levels were significantly lower in Eca109R60/2Gy cells than in Eca109 cells. Therefore, our findings demonstrated that radioresistance was affected by the expression of HOTAIR and biomarkers of the EMT and CSCs.

The expression and significance of HOX transcript antisense RNA and epithelial-mesenchymal transition-related factors in esophageal squamous cell carcinoma.

The present study investigated the correlation and significance of HOX transcript antisense RNA (HOTAIR) and epithelial-mesenchymal transition (EMT)-related factors in the occurrence and metastasis of esophageal squamous cell cancer (ESCC) progression. The mRNA and protein expression levels of HOTAIR and EMT­related factors were detected in 96 ESCC and para­carcinoma tissues using reverse transcription­quantitative polymerase chain reaction and western blot analysis. The expression levels of these factors, and the correlation between these factors and clinicopathological characteristics were subsequently analyzed. HOTAIR mRNA expression levels were significantly higher in ESCC compared with in para-carcinoma tissues, and HOTAIR mRNA expression levels were significantly higher in the groups with lymph node involvement or organ metastasis compared with the group without. Furthermore, HOTAIR expression levels demonstrated a significant increasing trend from well­differentiated cancer to poorly differentiated cancer. The mRNA and protein expression levels of zinc finger protein SNAI1 (Snail) and ß­catenin in ESCC were significantly higher compared with para-carcinoma tissues, whereas E­cadherin mRNA and protein expression levels were lower in ESCC tissues compared with in para-carcinoma tissues. Snail mRNA and protein expression levels were also significantly higher in groups with lymph node involvement or organ metastasis compared with those without, and ß­catenin protein expression levels were significantly higher in the groups with lymph node involvement or organ metastasis compared with the group without. In the 96 ESCC tissues, HOTAIR mRNA expression levels were positively correlated with Snail mRNA and protein expression levels, and were negatively correlated with E­cadherin expression levels. HOTAIR mRNA expression levels were also positively correlated with ß­catenin mRNA expression levels. In conclusion, HOTAIR may be involved in carcinogenesis and metastasis, and may induce the expression of EMT­related factors; detection of these factors may assist in early diagnosis and prognostic prediction.