Construction of Hydrocarbon Nanobelts Shi, Tan‐Hao; Tong, Shuo; Wang, Mei‐Xiang
Angewandte Chemie International Edition,
May 11, 2020, Letnik:
59, Številka:
20
Journal Article
Recenzirano
Linearly fused hydrocarbon nanobelts are a unique type of double‐stranded macrocycles that would serve as not only the powerful hosts in supramolecular science but also the templates to grow zig‐zag ...carbon nanotubes with defined diameters. Fully conjugated hydrocarbon nanobelts such as beltnarenes would also possess unique physical and chemical properties. Despite the importance, both fully conjugated and (partially) saturated hydrocarbon nanobelts remain largely unexplored because of the lack of cyclization methods. Reported here is the construction of nanometer sized H12‐belt12arenes based on the strategy to close up all fjords of resorcin6arene by means of six‐fold intramolecular alkylation reactions of resorcin6arene derivatives. All resulting H12‐belt12arenes produce a very similar nanobelt core structure with six benzene rings and six boat 1,4‐cyclohexadiene rings being alternately linear‐fused to give a nearly equilateral hexagonal cylinder. The average long diagonal is around 1 nm and the height of the cylinder is about 0.3 nm. The acquired H12‐belt12arenes would be the potential precursors to various hydrocarbon nanobelts including fully conjugated belt12arenes.
Stitching all fjords! H12‐Belt12arenes as a novel type of hydrocarbon nanobelts were constructed effectively from one‐pot six‐fold intramolecular alkylation reactions of both hexa(isopropenyl)‐substituted and hexa(hydroxyl(aryl)methyl)‐substituted resorcin6arene derivatives.
To ascertain the role of the solidification cell structures on the mechanical performance of Al-Si-(Mg) alloys processed using the laser powder bed fusion (LPBF) technique, micropillar compression ...tests were performed on LPBF Al-10Si-0.3Mg (AlSi10Mg). The alloy's microstructure consists of submicron-scale cellular structures, dense dislocation networks, and dispersed nanoscale Si precipitates. The stress-strain responses of the micropillars are devoid of pronounced serrations and the yield strength and work hardening behaviors are size-independent. A comparison of the micropillar compression responses of the LPBF AlSi10Mg, 316 L stainless steel and Inconel 718 alloy, and nano-and micro-crystalline alloys is made. In LPBF AlSi10Mg, the combination of dislocation networks and shear-resistant Si particles resist the dislocation motion significantly and enhance dislocation storage. This results in the cellular structure dominating the strength and plastic flow. These results show a pathway for designing high strength alloys via additive manufacturing.
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Fused Deposition Modeling (FDM) can be used to manufacture any complex geometry and internal structures, and it has been widely applied in many industries, such as the biomedical, manufacturing, ...aerospace, automobile, industrial, and building industries. The purpose of this research is to characterize the polylactic acid (PLA) and polyethylene terephthalate glycol (PETG) materials of FDM under four loading conditions (tension, compression, bending, and thermal deformation), in order to obtain data regarding different printing temperatures and speeds. The results indicated that PLA and PETG materials exhibit an obvious tensile and compression asymmetry. It was observed that the mechanical properties (tension, compression, and bending) of PLA and PETG are increased at higher printing temperatures, and that the effect of speed on PLA and PETG shows different results. In addition, the mechanical properties of PLA are greater than those of PETG, but the thermal deformation is the opposite. The above results will be a great help for researchers who are working with polymers and FDM technology to achieve sustainability.
The science and technology aspects of electronic nose (E-nose) has been developed rapidly in last decade (2006-2016). This paper reviews of the publications that that cover the developments in ...science and technological aspects of electronic nose together with its application in fresh foods. The first part of this review covers the sensing and pattern recognition system (PR) of E-nose. The second part covers the application of E-nose in classification, flavor detection, and evaluation of spoilage in fresh foods area. With more new sensor materials to be found and more combination between E-nose and other analysis technologies, the usages of E-nose in fresh foods will have wider prospects.
Lysosome is a key subceilular organelle in the execution of the autophagic process and at present little is known whether lysosomal function is controlled in the process of autophagy. In this study, ...we first found that suppression of mammalian target of rapamycin （mTOR） activity by starvation or two mTOR catalytic inhibitors （PP242 and To- rinl）, but not by an allosteric inhibitor （rapamycin）, leads to activation of lysosomal function. Second, we provided evidence that activation of lysosomal function is associated with the suppression of mTOR complex 1 （mTORC1）, but not mTORC2, and the mTORC1 localization to lysosomes is not directly correlated to its regulatory role in lysosomal function. Third, we examined the involvement of transcription factor EB （TFEB） and demonstrated that TFEB acti- vation following mTORC1 suppression is necessary but not sufficient for lysosomal activation. Finally, Atg5 or Atg7 deletion or blockage of the autophagosome-lysosome fusion process effectively diminished lysosomal activation, sug- gesting that lysosomal activation occurring in the course of autophagy is dependent on autophagosome-lysosome fu- sion. Taken together, this study demonstrates that in the course of autophagy, lysosomal function is upregulated via a dual mechanism involving mTORC1 suppression and autophagosome-lysosome fusion.
Background
With the onset of the coronavirus disease 2019 (COVID‐19) pandemic, many experts expected that asthma‐associated morbidity because of severe acute respiratory syndrome coronavirus 2 ...infection would dramatically increase. However, some studies suggested that there was no apparent increasing in asthma‐related morbidity in children with asthma, it is even possible children may have improved outcomes. To understand the relationship between the COVID‐19 pandemic and asthma outcomes, we performed this article.
Methods
We searched PubMed, Embase, and Cochrane Library to find literature from December 2019 to June 2021 related to COVID‐19 and children's asthma control, among which results such as s, comments, letters, reviews, and case reports were excluded. The level of asthma control during the COVID‐19 pandemic was synthesized and discussed by outcomes of asthma exacerbation, emergency room visit, asthma admission, and childhood asthma control test (c‐ACT).
Results
A total of 22,159 subjects were included in 10 studies. Random effect model was used to account for the data. Compared with the same period before the COVID‐19 pandemic, asthma exacerbation reduced (odds ratio OR = 0.26, 95% confidence interval CI = 0.14–0.48, Z = 4.32, p < 0.0001), the odds of emergency room visit decreased as well (OR = 0.11, 95% CI = 0.04–0.26, Z = 4.98, p < 0.00001). The outcome of asthma admission showed no significant difference (OR = 0.84, 95% CI = 0.32–2.20, Z = 0.36, p = 0.72). The outcome of c‐ACT scores were not analyzed because of the different manifestations used. Overall, c‐ACT scores reduced during the pandemic.
Conclusion
Compared to the same period before the COVID‐19 pandemic, the level of asthma control has been significantly improved. We need to understand the exact factors leading to these improvements and find methods to sustain it.
Few-layer bismuthene is an emerging two-dimensional material in the fields of physics, chemistry, and material science. However, its nonlinear optical property and the related photonics device have ...been seldom studied so far. Here, we demonstrate a sub-200 fs soliton mode-locked erbium-doped fiber laser (EDFL) using a microfiber-based bismuthene saturable absorber for the first time, to the best of our knowledge. The bismuthene nanosheets are synthesized by the sonochemical exfoliation method and transferred onto the taper region of a microfiber by the optical deposition method. Stable soliton pulses centered at 1561 nm with the shortest pulse duration of about 193 fs were obtained. Our findings unambiguously imply that apart from its fantastic electric and thermal properties, few-layer bismuthene may also possess attractive optoelectronic properties for nonlinear photonics, such as mode-lockers, Q-switchers, optical modulators and so on.
Cancer stem cells are undifferentiated cancer cells that have self‐renewal ability, a high tumorigenic activity, and a multilineage differentiation potential. MicroRNAs play a critical role in ...regulating gene expression during carcinogenesis. Here, we investigated the role of miR‐7 and the mechanism by which it is dysregulated in gastric cancer stem cells (GCSCs). The stem cell marker, CD44, was used to sort GCSCs by fluorescence‐activated cell sorting. We found that CD44 (+) cells have higher invasiveness and form more number of sphere colonies than CD44 (−) cells. Quantitative real‐time polymerase chain reaction (PCR) revealed that the miR‐7‐5p expression was remarkably downregulated in GCSCs but was significantly increased in the methionine‐deprived medium. The downregulation of miR‐7‐5p results from the increased DNA methylation in the promoter region using the methylation‐specific PCR. Overexpression of miR‐7‐5p reduced the formation of colony and decreased the invasion of GCSCs through targeting Smo and Hes1 and subsequent repressing Notch and Hedgehog signaling pathways in vitro. Notably, upregulating miR‐7‐5p inhibited the growth of tumor in the xenograft model. Hence, these data demonstrated that miR‐7‐5p represses GCSC invasion through inhibition of Smo and Hes1, which provides a potential therapeutic target of gastric cancer treatment.
This paper mainly talks about the Cauchy two-matrix model and its corresponding integrable hierarchy with the help of orthogonal polynomial theory and Toda-type equations. Starting from the symmetric ...reduction in Cauchy biorthogonal polynomials, we derive the Toda equation of CKP type (or the C-Toda lattice) as well as its Lax pair by introducing time flows. Then, matrix integral solutions to the C-Toda lattice are extended to give solutions to the CKP hierarchy which reveals the time-dependent partition function of the Cauchy two-matrix model is nothing but the
τ
-function of the CKP hierarchy. At last, the connection between the Cauchy two-matrix model and Bures ensemble is established from the point of view of integrable systems.
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