Intermolecular 3 + 2 annulation is one of the most straightforward approaches to construct five membered heterocycles. However, it generally requires the use of functionalized substrates. An ideal ...reaction approach is to achieve dehydrogenative 3 + 2 annulation under oxidant-free conditions. Here we show an electrooxidative 3 + 2 annulation between phenols and N-acetylindoles under undivided electrolytic conditions. Neither external chemical oxidants nor metal catalysts are required to facilitate the dehydrogenation processes. This reaction protocol provides an environmentally friendly way for the selective synthesis of benzofuroindolines. Various N-acetylindoles bearing different C-3 and C-2 substituents are suitable in this electrochemical transformation, furnishing corresponding benzofuroindolines in up to 99% yield.Electrochemical oxidation provides a green alternative to the use of hazardous chemical oxidants and forcing conditions. Here, the authors show the electrocatalytic cross-coupling of phenols and indoles to generate biologically relevant benzofuroindolines in high yields.
Binary Linear Locally Repairable Codes Pengfei Huang; Yaakobi, Eitan; Uchikawa, Hironori ...
IEEE transactions on information theory,
11/2016, Volume:
62, Issue:
11
Journal Article
Peer reviewed
Open access
Locally repairable codes (LRCs) are a class of codes designed for the local correction of erasures. They have received considerable attention in recent years due to their applications in distributed ...storage. Most existing results on LRCs do not explicitly take into consideration the field size q, i.e., the size of the code alphabet. In particular, for the binary case, only a few results are known. In this paper, we present an upper bound on the minimum distance d of linear LRCs with availability, based on the work of Cadambe and Mazumdar. The bound takes into account the code length n, dimension k, locality r, availability t, and field size q. Then, we study the binary linear LRCs in three aspects. First, we focus on analyzing the locality of some classical codes, i.e., cyclic codes and Reed-Muller codes, and their modified versions, which are obtained by applying the operations of extend, shorten, expurgate, augment, and lengthen. Next, we construct LRCs using phantom parity-check symbols and multi-level tensor product structure, respectively. Compared with other previous constructions of binary LRCs with fixed locality or minimum distance, our construction is much more flexible in terms of code parameters, and gives various families of high-rate LRCs, some of which are shown to be optimal with respect to their minimum distance. Finally, the availability of LRCs is studied. We investigate the locality and availability properties of several classes of one-step majority-logic decodable codes, including cyclic simplex codes, cyclic difference-set codes, and 4-cycle free regular low-density parity-check codes. We also show the construction of a long LRC with availability from a short one-step majority-logic decodable code.
Highlights
As an emerging preparation strategy for MXenes, Lewis acidic etching has attracted increasing attention in the past few years benefiting from a series of merits.
Lewis acidic etching ...method is mainly presented from etching mechanism, terminations regulation, in-situ formed metals and delamination of multi-layered MXenes.
The applications of MXenes and MXene-based composites obtained by Lewis acidic etching route in energy storage and conversion, sensors and microwave absorption are carefully summarized.
Since the discovery in 2011, MXenes have become the rising star in the field of two-dimensional materials. Benefiting from the metallic-level conductivity, large and adjustable gallery spacing, low ion diffusion barrier, rich surface chemistry, superior mechanical strength, MXenes exhibit great application prospects in energy storage and conversion, sensors, optoelectronics, electromagnetic interference shielding and biomedicine. Nevertheless, two issues seriously deteriorate the further development of MXenes. One is the high experimental risk of common preparation methods such as HF etching, and the other is the difficulty in obtaining MXenes with controllable surface groups. Recently, Lewis acidic etching, as a brand-new preparation strategy for MXenes, has attracted intensive attention due to its high safety and the ability to endow MXenes with uniform terminations. However, a comprehensive review of Lewis acidic etching method has not been reported yet. Herein, we first introduce the Lewis acidic etching from the following four aspects: etching mechanism, terminations regulation, in-situ formed metals and delamination of multi-layered MXenes. Further, the applications of MXenes and MXene-based hybrids obtained by Lewis acidic etching route in energy storage and conversion, sensors and microwave absorption are carefully summarized. Finally, some challenges and opportunities of Lewis acidic etching strategy are also presented.
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An equiatomic CoCrFeNiMn high-entropy alloy (HEA) powder is produced by vacuum induction melting gas-atomization with argon gas. A detailed characterization reveals that gas atomized HEA powder is ...suitable for powder-bed-fusion additive manufacturing (PBFAM). Therefore, the powder with size ranging from 45 to 106μm is applied in one of PBFAM, electron beam melting (EBM). The final EBM part is strongly affected by the feedstock. The entrapped gas pores result in a high porosity of EBM-built parts, requesting extra efforts to eliminate the pores for processing parameters optimization. After the optimization, the highly dense EBM-built parts with a hierarchical microstructure and a strong 〈100〉 texture are obtained. The hierarchical microstructure displays long columnar grains containing intragranular cellular structure (dendrites) along build direction. Deformation mechanism of the EBM-built CoCrFeNiMn HEA is dominated by dislocation with limited contribution from mechanical twinning. Experimental results reveal that the cellular structure (dendrites) does not contribute the strength without the pre-existing surrounding dislocation network. As a result, EBM-built CoCrFeNiMn HEA parts exhibit comparable tensile properties to their conventional cast counterparts. It is suggested that the EBM process and gas atomized HEA powder can be employed for fabricating single-phase HEA parts with complex geometry and good mechanical properties.
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•This is the first detailed report regarding the EBM-built single-phase high entropy alloy (HEA) parts.•Gas atomized HEA powder is proved to be suitable for powder-bed-fusion additive manufacturing to develop new material.•Deformation mechanism of the EBM-built HEA is dominated by dislocation with limited contribution of mechanical twinning.•The cellular structure does not contribute the strength without the pre-existing surrounding dislocation network.•HEA parts with complex geometry and good mechanical properties can be obtained using EBM process and gas atomized powder.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel Estrone (E1) molecularly imprinted polymers (MIPs-E1)-coated solid-phase microextraction (SPME) fiber was prepared by in-situ polymerization on inner and outer surface of the capillary, ...namely MIPs-E1-coated in-out-tube SPME (MIPs-E1-IOT-SPME), which combines the advantages of enhanced extraction efficiencies of IOT-SPME and specific adsorption abilities of MIPs, and shows nearly double enrichment capacity compared to in-tube SPME (IT-SPME). The extraction conditions were optimized and a method for determination six endocrine disrupting compounds (EDCs) by MIPs-E1-IOT-SPME coupled with HPLC is developed. The MIPs-E1 coating was characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), N2 adsorption-desorption and Thermal gravimetric analysis (TGA). Under the optimum condition, the MIPs-IOT-SPME-HPLC method shows low limits of detection (LODs) (0.21–0.80 μg L−1) and limits of quantification detection (LOQs) (0.69–2.6 μg L−1), wide linear ranges from 10.0 to 1000 μg L−1 for each compound with exception of E2 and E3 from 20.0 to 1000 μg L−1, and acceptable reproducibility of one fiber for five parallel determinations is 2.4–6.6% (RSD) and fiber-to-fiber is 4.5–8.1% (RSD). The satisfactory recoveries are in the range of 88.5–105.1% with good RSDs less than 7.9% at the five spiked levels of 20.0, 50.0, 80.0, 200.0 and 500.0 μg L−1. Moreover, when compared with commercial fibers, the MIPs-E1-IOT-SPME fiber displays excellent adsorption capacity and specific selectivity.
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•An Estrone (E1) molecularly imprinted polymers-coated solid-phase microextraction fiber was prepared.•The novel SPME fiber was constructed by in-situ polymerization on inner and outer surface of the capillary.•The homemade SPME fiber shows double enrichment capacity and excellent specific selectivity compared to commercial fibers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Surface ultrasonic rolling process (SURP) is a prior self-nano-technology of surface strengthening to improve the cavitation resistance of metal materials. In the paper, the 304 stainless steel ...(304SS) specimens were processed into 5 times, 10 times, 15 times and 20 times by SURP, then were cut into pieces along the SURP surface. In order to investigate impact of SURP on cavitation erosion behavior of 304SS, microstructure, mechanical properties and phase distribution of 304SS with difference SURP times were characterized firstly. Subsequently, ultrasonic cavitation erosion process and electrochemical measurements was experimented respectively: the specimens with different SURP times were subjected to 3 h in ore pulp solution (The mass fraction of 3.5% NaCl and 5% plumbum-zinc) by ultrasonic cavitation erosion process (UCEP), meanwhile, the electrochemical behaviors of the 304SS specimens with difference SURP times, such as open circuit potential (OCP), polarization curves and electrochemical impedance spectroscopy (EIS) were measured successively. Finally, the influences of the mechanical properties and corrosion characteristics of the 304SS with different microstructures after SURP on cavitation corrosion resistance were discussed in details, in the meantime, the microscopic mechanisms of the cavitation resistance for 304SS with different SURP times were investigated. The result shows that SURP is significantly beneficial to protect 304SS from the cavitation erosion behavior via introduction of deformation layers, transformation between martensite and austenitic, formation of passivation film, grain refinement and the surface hardness as well as residual stress of the 304SS were enhanced accordingly. However, the energy transfer of SURP is not only used to surface hardening, grain refinement, slip bands establishment but also defects formation, overmuch energy transfer plays the opposite role. Therefore SURP 10 times is a suitable SURP times that makes 304SS achieved optimal cavitation resistance.
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•304SS specimens were processed by surface ultrasonic rolling process (SURP).•Microstructure, mechanical properties and phase of SURP specimens were characterized.•Ultrasonic cavitation process and electrochemical measurement were test respectively.•SURP is significantly beneficial to protect 304SS from cavitation erosion behavior.•SURP 10 times is the proper time makes 304SS achieved optimal cavitation resistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The enhanced liver fibrosis test (ELF) has been shown to accurately predict significant liver fibrosis in several liver diseases.
To perform a meta-analysis to assess the performance of the ELF test ...for the assessment of liver fibrosis.
Electronic and manual searches were performed to identify studies of the ELF test. After methodological quality assessment and data extraction, pooled estimates of the sensitivity, specificity, area under the receiver operating characteristic curve (AUROC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and summary receiver operating characteristics (sROC) were assessed systematically. The extent of heterogeneity and reasons for it were assessed.
Nine studies were identified for analysis. The pooled sensitivity, specificity, positive LR, negative LR, and DOR values of ELF test, for assessment of significant liver fibrosis, were 83% (95% CI=0.80-0.86), 73% (95% CI=0.69-0.77), 4.00 (95% CI=2.50-6.39), 0.24 (95% CI=0.17-0.34), and 16.10 (95% CI=8.27-31.34), respectively; and, for evaluation of severe liver fibrosis, were 78% (95% CI=0.74-0.81), 76% (95% CI=0.73-0.78), 4.39 (95% CI=2.76-6.97), 0.27 (95% CI=0.16-0.46), and 16.01 (95% CI: 7.15-35.82), respectively; and, for estimation of cirrhosis, were 80% (95% CI=0.75-0.85), 71% (95% CI=0.68-0.74), 3.13 (95% CI=2.01-4.87), 0.29 (95% CI=0.19-0.44), and 14.09 (95% CI: 5.43-36.59), respectively.
The ELF test shows good performance and considerable diagnostic value for the prediction of histological fibrosis stage.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the natural environment, plants often face unfavorable factors such as drought, cold, and freezing, which affect their growth and yield. The MYB (v-myb avian myeloblastosis viral oncogene homolog) ...transcription factor family is widely involved in plant responses to biotic and abiotic stresses. In this study,
(L.) Borkh was used as the research material, and a gene
of the MYB family was cloned from it. The open reading frame (ORF) of
was found to be 762 bp, encoding 253 amino acids; sequence alignment results and predictions of the protein structure indicated that the MbMYB4 protein contained the conserved MYB domain. Subcellular localization showed that MbMYB4 was localized in the nucleus. In addition, the use of quantitative real-time PCR (qPCR) technology found that the expression of
was enriched in the young leaf and root, and it was highly affected by cold and drought treatments in
seedlings. When
was introduced into
, it greatly increased the cold and drought tolerance in the transgenic plant. Under cold and drought stresses, the proline and chlorophyll content, and peroxidase (POD) and catalase (CAT) activities of transgenic
increased significantly, and the content of malondialdehyde (MDA) and the relative conductivity decreased significantly, indicating that the plasma membrane damage of transgenic
was lesser. Therefore, the overexpression of the
gene in
can enhance the tolerance of transgenic plants to cold and drought stresses.
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Freestanding multicapsular carbon fibers (MCFs) cloth was synthesized by electrospinning and applied as interfacial layer to regulate the plating/stripping behavior of Zn anodes.
MCFs ...layer is supposed to uniformize the electric field and Zn
2+
flux, and the moderate zincophilicity enables the bottom-up deposition of Zn on Zn@MCFs anode, thereby leading to high-quality and rapid Zn deposition kinetics.
Superior electrochemical performance of Zn@MCFs is achieved in symmetrical, asymmetrical and Zn||MnO
2
batteries, including long cycling life, high coulombic efficiency and excellent rate performance.
Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security, high energy density, low cost, and environmental friendliness. However, deep-seated problems including Zn dendrite and adverse side reactions severely impede the practical application. In this work, we proposed a freestanding Zn-electrolyte interfacial layer composed of multicapsular carbon fibers (MCFs) to regulate the plating/stripping behavior of Zn anodes. The versatile MCFs protective layer can uniformize the electric field and Zn
2+
flux, meanwhile, reduce the deposition overpotentials, leading to high-quality and rapid Zn deposition kinetics. Furthermore, the bottom-up and uniform deposition of Zn on the Zn-MCFs interface endows long-term and high-capacity plating. Accordingly, the Zn@MCFs symmetric batteries can keep working up to 1500 h with 5 mAh cm
−2
. The feasibility of the MCFs interfacial layer is also convinced in Zn@MCFs||MnO
2
batteries. Remarkably, the Zn@MCFs||α-MnO
2
batteries deliver a high specific capacity of 236.1 mAh g
−1
at 1 A g
−1
with excellent stability, and maintain an exhilarating energy density of 154.3 Wh kg
−1
at 33% depth of discharge in pouch batteries.
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Shaping codes are used to encode information for use on channels with cost constraints. Applications include data transmission with a power constraint and, more recently, data storage on flash ...memories with a constraint on memory cell wear. In the latter application, system requirements often impose a rate constraint. In this paper, we study rate-constrained fixed-to-variable length shaping codes for noiseless, memoryless costly channels and general i.i.d. sources. The analysis relies on the theory of word-valued sources. We establish a relationship between the code expansion factor - the ratio of the expected codeword length to the length of the input source word - and the minimum average symbol cost. We then determine the expansion factor that minimizes the average cost per source symbol (total cost), corresponding to a conventional optimal source code with cost. An equivalence is established between codes minimizing average symbol cost and codes minimizing total cost, and a separation theorem is proved, showing that optimal shaping can be achieved by a concatenation of optimal compression and optimal shaping for a uniform i.i.d. source. Shaping codes often incorporate, either explicitly or implicitly, some form of non-equiprobable signaling. We use our results to further explore the connections between shaping codes and codes that map a sequence of i.i.d. source symbols into an output sequence of symbols that are approximately independent and distributed according to a specified target distribution, such as distribution matching (DM) codes. Optimal DM codes are characterized in terms of a new performance measure - generalized expansion factor (GEF) - motivated by the costly channel perspective. The GEF is used to study DM codes that minimize informational divergence and normalized informational divergence.
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