Precisely and conveniently controlling the handedness and magnitude of circularly polarized luminescence (CPL) is a key issue in developing CPL-active materials. In this work, a series of chiral ...helical polyacetylenes bearing pendant pyrene groups were synthesized. CPL inversion occurred when the polymer solutions fabricated into thin solid films. More interestingly, amplification of CPL was also observed during this process; that is, the polymer solution showed a luminescence dissymmetry factor (g lum) of 1 × 10–3, while over 100-fold magnitude amplification of g lum values is obtained in the polymer films. Significantly, the g lum values of the films can be regulated from 10–1 to 10–3 by simply changing the film-forming solvents. The cause of the above phenomena is due to the presence of two different chirality transfer channels: intermolecular interactions in the solutions and the “matching rule” in the films. This study provides a new strategy to construct CPL materials with tunable handedness and a large dissymmetry factor.
A novel strategy for the N‐arylation of NH‐sulfoximines has been developed by merging nickel catalysis and electrochemistry (in an undivided cell), thereby providing a practical method for the ...construction of sulfoximine derivatives. Paired electrolysis is employed in this protocol, so a sacrificial anode is not required. Owing to the mild reaction conditions, excellent functional group tolerance and yield are achieved. A preliminary mechanistic study indicates that the anodic oxidation of a NiII species is crucial to promote the reductive elimination of a C−N bond from the resulting NiIII species at room temperature.
A novel strategy for the N‐arylation of NH‐sulfoximines has been developed by merging nickel catalysis and electrochemistry (in an undivided cell), thereby providing a practical method for the synthesis of sulfoximine derivatives. Paired electrolysis is employed in this protocol, so a sacrificial anode is not required.
The ability to produce random numbers that are unknown to any outside party is crucial for many applications. Device-independent randomness generation1–4 does not require trusted devices and ...therefore provides strong guarantees of the security of the output, but it comes at the price of requiring the violation of a Bell inequality for implementation. A further challenge is to make the bounds in the security proofs tight enough to allow randomness expansion with contemporary technology. Although randomness has been generated in recent experiments5–9, the amount of randomness consumed in doing so has been too high to certify expansion based on existing theory. Here we present an experiment that demonstrates device-independent randomness expansion1–3,10–15. By developing a Bell test setup with a single-photon detection efficiency of around 84% and by using a spot-checking protocol, we achieve a net gain of 2.57 × 108 certified bits with a soundness error of 3.09 × 10−12. The experiment ran for 19.2 h, which corresponds to an average rate of randomness generation of 13,527 bits per second. By developing the entropy accumulation theorem4,16,17, we establish security against quantum adversaries. We anticipate that this work will lead to further improvements that push device-independence towards commercial viability.Device-independent randomness expansion is demonstrated in an experiment that is secure against quantum adversaries as established by the entropy accumulation theorem.
The "Internet +" era presents new possibilities and new requirements for ESP education. Online teaching under the background of the "Internet +" is to enable learners to make efficient use of ...fragmented time. The process and requirement of blended teaching is to break through the ideology of "learning only in the classroom", so that students can spend time in learning even after class. There is a problem of overload of information in online platform teaching, which puts a certain burden on students' knowledge construction, aggravates the cognitive load of students, and the lacks of teachers' summarization and guidance. The article is to explore how to build a blended ESP learning model and corresponding performance evaluation system to make ESP learning in the "Internet +" context more systematic and efficient.
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Organic electrosynthesis has been widely used as an environmentally conscious alternative to conventional methods for redox reactions because it utilizes electric current as a ...traceless redox agent instead of chemical redox agents. Indirect electrolysis employing a redox catalyst has received tremendous attention, since it provides various advantages compared to direct electrolysis. With indirect electrolysis, overpotential of electron transfer can be avoided, which is inherently milder, thus wide functional group tolerance can be achieved. Additionally, chemoselectivity, regioselectivity, and stereoselectivity can be tuned by the redox catalysts used in indirect electrolysis. Furthermore, electrode passivation can be avoided by preventing the formation of polymer films on the electrode surface. Common redox catalysts include N-oxyl radicals, hypervalent iodine species, halides, amines, benzoquinones (such as DDQ and tetrachlorobenzoquinone), and transition metals. In recent years, great progress has been made in the field of indirect organic electrosynthesis using transition metals as redox catalysts for reaction classes including C–H functionalization, radical cyclization, and cross-coupling of aryl halides-each owing to the diverse reactivity and accessible oxidation states of transition metals. Although various reviews of organic electrosynthesis are available, there is a lack of articles that focus on recent research progress in the area of indirect electrolysis using transition metals, which is the impetus for this review.
Developing low‐cost, high‐performance electro‐catalysts is essential for large‐scale application of electrochemical energy devices. In this article, reported are the findings in understanding and ...controlling oxygen defects in PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) for significantly enhancing the rate of oxygen evolution reaction (OER) are reported. Utilizing surface‐sensitive characterization techniques and first‐principle calculations, it is found that excessive oxygen vacancies promote OH− affiliation and lower the theoretical energy for the formation of O* on the surface, thus greatly facilitating the OER kinetics. On the other hand, however, oxygen vacancies also increase the energy band gap and lower the O 2p band center of PBSCF, which may hinder OER kinetics. Still, careful tuning of these competing effects has resulted in enhanced OER activity for PBSCF with oxygen defects. This work also demonstrates that oxygen defects generated by different techniques have very different characteristics, resulting in different impacts on the activity of electrodes. In particular, PBSCF nanotubes after electrochemical reduction exhibit outstanding OER activity compared with the recently reported perovskite‐based catalysts.
Oxygen vacancies in PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) are found to promote OH‐ affiliation and lower the theoretical energy for the formation of O* on the surface. However, oxygen vacancies also increase the energy band gap and lower the O 2p band center of PBSCF. Careful tuning of these competing effects has resulted in enhanced oxygen evolution reaction activity for PBSCF with oxygen defects.
Esophageal squamous cell carcinoma (ESCC) is one of the deadliest cancers. We performed exome sequencing on 113 tumor-normal pairs, yielding a mean of 82 non-silent mutations per tumor, and 8 cell ...lines. The mutational profile of ESCC closely resembles those of squamous cell carcinomas of other tissues but differs from that of esophageal adenocarcinoma. Genes involved in cell cycle and apoptosis regulation were mutated in 99% of cases by somatic alterations of TP53 (93%), CCND1 (33%), CDKN2A (20%), NFE2L2 (10%) and RB1 (9%). Histone modifier genes were frequently mutated, including KMT2D (also called MLL2; 19%), KMT2C (MLL3; 6%), KDM6A (7%), EP300 (10%) and CREBBP (6%). EP300 mutations were associated with poor survival. The Hippo and Notch pathways were dysregulated by mutations in FAT1, FAT2, FAT3 or FAT4 (27%) or AJUBA (JUB; 7%) and NOTCH1, NOTCH2 or NOTCH3 (22%) or FBXW7 (5%), respectively. These results define the mutational landscape of ESCC and highlight mutations in epigenetic modulators with prognostic and potentially therapeutic implications.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Approaches of machine translation are streamlined into three types based on strategies of knowledge processing, i.e. syntax-based methods, rule-based methods, and corpus-based methods, with their ...merits and demerits assessed. Consequently, the updated research tendency of the neural networks, as the current mainstream methods of machine translation, mainly comprising computational complexity reducing, words alignment enhancing, prior knowledge and constraints incorporating are stressed. Eventually, the future development orientations of the mainstream methods of neutral machine translation, particularly that of networks integration, data parallelizing and training are prospected.
Biodegradable nanoprodrugs, inheriting the antitumor effects of chemotherapy drugs and overcoming the inevitable drawback of side effects on normal tissues, hold promise as next‐generation cancer ...therapy candidates. Biodegradable nanoprodrugs of transferrin‐modified MgO2 nanosheets are developed to selectively deliver reactive oxygen species to cancer cells for molecular dynamic therapy strategy. The nanosheets favor the acidic and low catalase activity tumor microenvironment to react with proton and release nontoxic Mg2+. This reaction simultaneously produces abundant H2O2 to induce cell death and damage the structure of transferrin to release Fe3+, which will react with H2O2 to produce highly toxic ·OH to kill tumor cells.
Biodegradable nanoprodrugs of transferrin‐modified MgO2 nanosheets are developed to selectively deliver reactive oxygen species to cancer cells for molecular dynamic therapy strategy. The nanosheets favor acidic conditions and low catalase activity in the tumor microenvironment to react with protons and release nontoxic Mg2+. This reaction simultaneously produces abundant H2O2 and highly toxic ·OH, which destroys tumor cells.
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