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Abstract: A newly chiral tertiary amine-squaramide has successfully developed and applied into the asymmetric Michael addition of 4-hydroxycoumarin to β,γ-unsaturated α-ketoesters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of coumarin derivatives were obtained with good yields and enantioselectivities.

A novel method for the challenging synthesis of unsymmetrically tetrasubstituted NH-pyrroles from chalcone derivatives is reported. The pyrrolo[1,2-a]pyrimidine derivatives that were synthesized from NH-pyrroles exhibit AIE and AIEE property.

Chiral amine-squaramide is a kind of effective hydrogen bond donor bifunctional catalyst to promote many asymmetric transformations. In this paper, novel chiral tertiary amine-squaramide derived from the natural product of the stevioside was developed and applied into the asymmetric Michael addition of acetylacetone to nitroolefins. This asymmetric reaction performed well, and a series of enantiomerically enriched compounds were obtained in high yields (up to 96%) with excellent enantioselectivities (up to 99% ee).

The flowers of Elaeagnus angustifolia L. have been used as a homologous variety in China, whose quality seriously relies on the compositions during the flowering period. Unfortunately, studies on the variations of volatile compounds during the flowering season are rarely reported. Herein, a gas chromatography-mass spectrometry-based untargeted metabolomic methodology was proposed for the comprehensive analysis of volatile compounds in E. angustifolia flowers to classify various flowering stages. Samples from four flowering stages were collected, including the initial bloom stage, pre-full bloom stage (70–80% of flowers), full bloom stage, and ending of the bloom stage. Simultaneous distillation extraction was used for the extraction of volatile compounds in the flowers, which was then analyzed by a newly developed chemometric data analysis tool, autoGCMSDataAnal. An advantage of the developed methodology is that compounds can be accurately screened and identified. Finally, 59 compounds that showed significant difference among four flowering stages were screened and 31 compounds were identified. Sample clustering results from principal component analysis and hierarchical clustering analysis suggested that flowers from the pre-full bloom stage and full bloom stage may be more suitable when used as raw materials for industrial products.

The convenient preparation of N2-unprotected five-membered cyclic guanidines was achieved through a cascade [3 + 2] cycloaddition between organo-cyanamides and α-haloamides under mild conditions in good to excellent yields (up to 99%). The corresponding cyclic guanidines could be easily transformed into hydantoins via hydrolysis.

Intracranial aneurysms (IA) are a huge threat to human health, with a global incidence rate of 0.65–8.4%. Although the microsurgical and interventional techniques have made profound progression in treating IA, the relatively high rate of complications and recurrence are still not satisfactory. Thus, there is a need to elucidate its molecular mechanism. Numerous studies have identified the close relationship between hemodynamic-induced inflammation and development of IA. Indeed, the dysfunction of endothelial cells, smooth muscle cells, macrophages and lymphocytes, as well as their secreted cytokines, collectively contribute to the formation, growth and rupture of IA. Furthermore, the immune system has also been identified to participate in the development of IA. This review will explore the mechanisms of various inflammatory cells and significant cytokines, providing a new perspective in the clinical treatment of IA.

A novel indolium-based fluorescent probe (probe 1) for the recognition and detection of hypochlorite (OCl−) has been explored via a double oxidation reaction mechanism. Probe 1 exhibited excellent selectivity and sensitivity for OCl− over other analytes, and with a detection limit of 0.11 μM. Meanwhile, probe 1 showed fast response toward OCl− in less than 3 min with obvious changes in color, which could be observed by naked eye. Moreover, fluorescence imaging experiments by using Eca109 cells were performed utilizing the new probe, demonstrating its practical applications in living cells.

The high voltage circuit breaker plays an important role in the circuit. In order to extend the service life of the circuit breaker, it is necessary to have materials with excellent ablation resistance. At present, The PTFE with boron nitride (BN) is widely used to produce the nozzle of high voltage circuit breaker. With the increase of BN filler particle size, the arc ablation performance of the composite increases gradually. In order to obtain the nozzle material with excellent ablation performances, nanoscale and microscale h-BN were divided into five groups with different mass ratio, then added into PTFE to prepare five kinds of composite materials with constant BN mass fraction. To study the influence of mass ratio on the thermal conductivity and arc ablation characteristics of PTFE/BN composites, arc ablation, thermal conductivity and spectral reflectance are tested. After adding microscale and nanoscale hybrid BN, the ablation amount of the composite decreased firstly and then increased, reaching the minimum in the third group. This work indicates there is a certain proportion with the excellent performance in arc ablation characteristics. This paper offers a feasible method for the preparation of PTFE/BN high-voltage circuit breaker.

As an important part of power equipment, high voltage circuit breakers play an important role in circuit breaking and isolating. However, during the breaking process of high voltage circuit breakers, arcs and recovery voltages are generated between the moving and stationary contacts, which may cause serious ablation and breakdown of the nozzles in the circuit breaker, shortening the life of the circuit breakers. Therefore, nozzles with superior performance are urgently needed. PTFE filled with different proportions of micron-BN and nano-BN was prepared in this paper to study the effect of hybrid fillers on the AC breakdown performance of PTFE. Scanning electron microscope (SEM) is used to characterize the dispersion state of micron-BN sheets and nano-BN sheets in PTFE matrix. The Thermally stimulated depolarization currents (TSDC) experiment is used to test and calculate the trap parameters of the sample. The AC breakdown experiment is used to test the breakdown strength of the specimen. The relationship between the breakdown performance and the change of trap parameters is discussed. And these factors are considered to be closely related.

During the breaking process of high voltage circuit breaker (HVCB), the arcs generated between the contacts may cause severe ablation of the nozzle, shortening the life of HVCB. Therefore, it is necessary to study the nozzle material with better ablation resistance. Polytetrafluoroethylene (PTFE)/boron nitride (BN) composite materials are commonly used in the industry to prepare nozzles. The particle size of BN can affect the ablation resistance of PTFE/BN composites, but the law is still unclear. In this paper, several kinds of PTFE composite samples doped with different nanoscale and micron-scale BN were prepared to study the effect of BN size on ablation resistance. The experimental results show that micron-scale BN fillers are more effective for improving the ablation resistance. With the increase of micron-scale BN particle size, the arc ablation resistance becomes better first and then worsens. The results are discussed and explained from the perspective of thermal transport and spectral reflectance characteristics.

With the development of high voltage transmission, higher voltage is necessary. Power equipment with traditional materials can not satisfy the insulation requirement of higher voltage transmission, so excellent material is urgently needed. PTFE nozzle is important in circuit breaker which faces the problem of arc ablation, and the nozzle with better performance is helpful to improve the transmission voltage. In this paper, in order to study the influence of different pressing pressures and modes on the ablation performance of PTFE/BN composites, four pressures and two modes were adopted (cold isostatic pressing and mould pressing) to obtain 7-wt% BN doped PTFE composites. As the pressing pressure increases, the ablation amount of the specimen decreases gradually. Compared with mould pressing, the specimen prepared by cold isostatic pressing has a higher thermal conductivity and lower ablation amount, while the light reflection properties are almost the same for both preparing methods. This paper is of great significance to improve the ablation resistance of nozzle materials.

A representative ferroelectric tetragonal potassium niobate (TKN) and antiferroelectric orthorhombic sodium niobate (ONN) crystalline powder samples were polarized by using an external electric field. The changes in lattice distortion and crystal symmetry of these samples polarized were revealed. The photocatalytic activities of the samples before and after the polarization were evaluated by photocatalytic decomposition of water and photocatalytic reduction of Ag+. The results imply that the polarization of such kind of perovskite-type niobate samples using the external electric field is one of effective ways to improve the photocatalytic performance, whether ferroelectric TKN or antiferroelectric ONN. The exploration of mechanism suggests that the polarization can change the ferroelectricity of niobate powder crystals. Furthermore, the photocatalytic activity on different exposed facets of these niobate crystals was also evaluated by detecting Ag content on the surfaces of sample via photocatalytic reduction of Ag+. It is found that {001} facet is the highest active facet of TKN, and {101} facet of ONN crystals has the highest photocatalytic activity among the exposed facets. The photocatalytic activity on each exposed facet can be increased to a certain extent by polarization, and the influence of polarization on photocatalytic activity is greater than that of surface energy. Keywords: Polarization, Photocatalytic activity, KNbO3, NaNbO3, Exposed facets

Image deconvolution problem is a challenging task in the field of image process. In this paper, an improved wiener filtering algorithm is proposed to accurately restore the degraded image of optical sparse aperture systems (OSAS). Differing from Wiener filter which needs to estimate the ratio of power spectrum of noise to power spectrum of original image, our algorithm analyzes the relationship between restored image and original image with the change of this ratio. Based on our algorithm, an optimum restored image in which the ring effect and smoothing effect are able to achieve a perfect balance can be gotten without additional estimation. Moreover, in the case of application to OSAS, several main factors which affect the restored image are expounded. Thus, applying this algorithm to image restoration of OSAS would be of great convenience.

BACKGROUND AND PURPOSE: The Low-Profile Visualized Intraluminal Support (LVIS) stent is a new device recently introduced for the treatment of wide-neck intracranial aneurysms. This single-center study presents the authors' preliminary experience using the LVIS stent to treat saccular aneurysms with parent arteries smaller than 2.5 mm. MATERIALS AND METHODS: Aneurysms with a LVIS stent used in a small parent vessel (

Tumor-associated macrophages (TAMs) play a regulatory role in inflammation and cancer. Exosomes derived from macrophages carrying microRNAs (miRNAs or miRs) are of great value for cancer therapy. Gremlin 1 (GREM1), a member of the antagonists of secreted bone morphogenetic protein, has been implicated in the pathophysiology of multiple diseases or cancers. Based on the predictions of miRNA–mRNA interaction, GREM1 was found to be a target gene of miR-155-5p. Here, the present study aims to explore the role of TAM-derived exosomal miR-155-5p by regulating GREM1 in intracranial aneurysm (IA). The collected results showed that GREM1 was down-regulated in IA, while miR-155-5p was up-regulated in TAM-derived exosomes. Smooth muscle cells (SMCs) were co-cultured with TAMs or exposed to exosomes derived from TAMs transfected with either miR-155-5p mimic or miR-155-5p inhibitor for exploring their roles in proliferation and migration of SMCs in vitro. Accordingly, in vitro experiments showed that TAM-derived exosomal miR-155-5p could promote proliferation and migration of SMCs by targeting GREM1. The effects of TAM-derived exosomal miR-155-5p on IA formation and TAM activation and infiltration by regulation of GREM1 in vivo were measured in IA rats injected with exosomes or those from TAMs transfected with miR-155-5p inhibitor. In vivo experimental results consistently confirmed that TAM-derived exosomes carrying miR-155-5p promoted IA formation and TAM activation and infiltration. In conclusion, TAM-derived exosomal miR-155-5p promotes IA formation via GREM1, which points to miR-155-5p as a possible therapeutic target for IA.

Supercapacitors possess an essential application in storing intermittent energy and powering electric vehicles or wearable electronics. It should be a promising approach by combining carbon nanomaterials with metal oxides to promote energy density and maintain high power density and durable stability. Herein, carbon nanotubes (CNTs) were firstly organized on the surface of nickel foam (NF) by a facile and mild (room temperature) metal-induced self-assembly process. Afterward, NiCoO2 nanosheets are bonded by CNTs films via hydrothermal method, and then the integrated NiCoO2@CNTs@NF electrodes were successfully fabricated. The kinds of self-supporting electrodes have some advantages of hierarchical three-dimensional (3D) network structure, strong binding force between NiCoO2 nanosheets and Ni foam substrate, excellent conductivity tunnel for ions and electrons transport, and abundant active sites for ions adsorption and fast faradic redox reaction. Accordingly, the NiCoO2@CNTs@NF integrated electrode present the superior capacitive properties and stabilities because of outstanding synergistic effect between CNTs as electric double-layer capacitance (EDLC) materials and NiCoO2 nanosheets as Faradic pseudocapacitance materials. Asymmetric supercapacitors (ASCs) were also fabricated based on NiCoO2@CNTs@NF electrodes and active carbon supported on Ni foam electrodes. The ASCs show prominent performances of a high special capacitance (151 F g−1 at 5 mA cm−2), an outstanding rate capability (83.8% when current densities changed from 5 to 50 mA cm−2), durable stability (above 90% after 5000 cycles), and a high energy density (56.0 Wh kg−1). Such three ASCs devices connected in series can light up four blue light-emitting diodes (LEDs) that operates at a minimum voltage of 2 V. The presented work provides an efficient approach to design an outstanding electrode by combining active materials with a metal substrate.

In order to analysis the electromagnetic coupling of field-to-line in a reverberation chamber, a multi-group plane-wave algorithm is proposed to simulate the electromagnetic field, which is considered to be the same field distributions as a real chamber within the test volume. The results derived by this algorithm for field-to-line coupling are very well agreed with the experiments and so verified the effectiveness of this algorithm. By using this method, the computer calculation time can be significantly reduced. Especially, this is very useful for high frequency field simulation in a reverberation chamber.

A novel ratiometric fluorescence probe (M1) for hypochlorite (ClO−) based on a mechanism of Fluorescent Resonance Energy Transfer (FRET) has been constructed. Probe M1 can be regarded as a difunctional probe for ClO− and Hg2+. Probe M1 exhibited good specificity and sensitivity towards ClO− over other related analytes as along with low detection limit (13.6 nM). Furthermore, it has been successfully used in living Eca109 cells for fluorescence imaging hypochlorite.

Endovascular treatment (EVT) of true posterior communicating artery (PcomA) aneurysms has been rarely reported. This study reports the outcomes on a single-center cohort with true PcomA aneurysms who underwent EVT. Between June 2011 and June 2017, clinical data from 42 patients with 43 true PcomA aneurysms who underwent EVT were retrieved from a prospectively maintained single-center database. Endovascular techniques, perioperative complications, clinical outcomes, and angiographic results were retrospectively evaluated. All aneurysms were treated successfully. Treatment modalities included simple coiling in 30 aneurysms, balloon-assisted coiling in two, and stent-assisted coiling in 11 cases. Immediate angiograms showed complete occlusion in 23 aneurysms (53.5%), residual neck in 8 cases (18.6%), and residual sac in 12 (27.9%). No procedure-related complications or mortality were observed. Of the 34 aneurysms that underwent angiographic follow-up at an average duration of 7.1 months post-procedure, complete occlusion was achieved in 22 (64.7%), neck remnant in eight (23.5%), and residual sac in four (11.8%) aneurysms, respectively. Six aneurysms (18.2%) that underwent conventional coiling developed recanalization and required retreatment. Seven cases that received stent-assisted coiling did not develop recurrence. Clinical follow-up (mean, 24.3 months) of all patients demonstrated no neurologic deterioration or (re)bleeding. EVT of the true PcomA aneurysm is a safe and feasible procedure but may be associated with recurrence in midterm follow-up, requiring close surveillance and potential retreatment.

Shortest path algorithm is a simple algorithm used for source recovery of underdetermined blind source separation (UBSS), but this algorithm is only applicable to the case where the number of sensors is two. However, in most real-life scenarios, the number of sensors is more than two. Then we proposed a smoothing method to improve the shortest path algorithm. The main thought is as follows: assume the number of sensors ism, select two adjacent observed signals to form a combination each time, then m — 1 kinds of combination are generated. As to each combination, recover their source signals by using the traditional shortest path algorithm, and m —1 groups of recovered source signals are derived, and then average the sum of all the corresponding signal values of m —1 groups. To verify the modified shortest path algorithm, simulations are performed when source signals are sufficiently sparse and insufficiently sparse respectively, and results show that the modified algorithm proposed in this paper is applicable when the number of sensors is two or more. The modified method enriches the tools that can be utilized for underdetermined source signal recovery.

A novel indolium-based fluorescent probe (probe 1) for the recognition and detection of hypochlorite (OCl

In underdetermined blind source separation (BSS) algorithms, source number estimation is a precondition and a difficulty. An improved source number estimation method based on wavelet analysis and singular value decomposition is pro-posed. First, the whitened observed signals are decomposed by wavelet analysis method. Next, the decomposed wavelet coefficients are reconstructed separately. Low frequency wavelet coefficients, the highest frequency wavelet coefficients, and original observed signals are chosen to form a new observed signals matrix. Then, covariance matrix of this new signal matrix is calculated, and eigenvalues of covariance matrix are calculated. Based on the obtained eigenvalues, a new calculation formula of judging threshold for source signals and noise is proposed. The proposed algorithm is validated by simulation.

BackgroundThe low profile visualized intraluminal support (LVIS) device is being increasingly used for the treatment of intracranial aneurysms. Its application in the basilar artery (BA) has not yet been reported.ObjectiveTo evaluate the safety and early efficacy of the LVIS device for the treatment of BA aneurysms.MethodsA prospectively maintained database was retrospectively reviewed for all patients with BA aneurysms treated by LVIS stents at our institution. Angiographic results were evaluated using the modified Raymond–Roy classification (mRRC).Results23 patients (mean age 52.8 years) with a BA aneurysm that was treated by LVIS stent implantation, with (n=21) or without (n=2) adjunctive coiling, were included in our study. 7 aneurysms were treated in the setting of subarachnoid hemorrhage (SAH). 10 aneurysms were located at the basilar tip, 10 at the basilar trunk, and 3 at the superior cerebellar artery. Procedure related complications developed in three patients (13%), including two perforator infarction and one worsening mass effect. Complications resulted in permanent morbidity (4%) in one case. One fatality was related to severe poor grade SAH. At a mean follow-up of 6.9 months, 13 of the 20 patients were mRRC I closure, 3 were mRRC II closure with an improvement from class IIIa, 3 were observed to be recanalized from class IIIa to IIIb, and 1 with stenting only was still patent similar to the immediate angiography.ConclusionThe LVIS stent represents a feasible and safe option for endovascular embolization of BA aneurysms. Although recanalization may occur after LVIS treatment, the mid term complete occlusion rate was acceptable.

The relation between symmetries and local conservation laws, known as Noether's theorem, plays an important role in modern theoretical physics. As a discrete analog of the differentiable physical system, a good numerical scheme should admit the discrete local conservation laws and inherent mathematical structures. A class of variational schemes constructed for the hydrodynamic-electrodynamic model of lossless free-electron gas in a quasi-neutral background shows good properties in secular simulations of surface plasmon polaritons [Q. Chen et al., Phys. Rev. E 99, 023313 (2019)]. We show the discrete local conservation laws admitted by these schemes. Based on the gauge symmetry of the discrete action functional, a discrete charge conservation law is realized locally, which is consistent with the discrete Euler-Lagrange equations obtained from the variational schemes. Based on the discrete Euler-Lagrange equations, discrete local momentum and energy conservation laws are derived directly, which are rigorous in theory. The preservation of the discrete local conservation laws and Lagrangian symplectic structure ensure that the numerical scheme is correct in physics., Comment: 15 pages

A class of variational schemes for the hydrodynamic-electrodynamic model of lossless free-electron gas in a quasineutral background is developed for high-quality simulations of surface plasmon polaritons. The Lagrangian density of lossless free-electron gas with a self-consistent electromagnetic field is established, and the dynamical equations with the associated constraints are obtained via a variational principle. Based on discrete exterior calculus, the action functional of this system is discretized and minimized to obtain the discrete dynamics. Newton-Raphson iteration and the biconjugate gradient stabilized method are equipped as a hybrid nonlinear-linear algebraic solver. Instead of discretizing the partial differential equations, the variational schemes have better numerical properties in secular simulations, as they preserve the discrete Lagrangian symplectic structure, gauge symmetry, and general energy-momentum density. Two numerical experiments were performed. The numerical results reproduce characteristic dispersion relations of bulk plasmons and surface plasmon polaritons, and the numerical errors of conserved quantities in all experiments are bounded by a small value after long-term simulations., Comment: 9 figures