Here we report that attempted preparation of low-valent Ca
complexes in the form of LCa-CaL (where L is a bulky β-diketiminate ligand) under dinitrogen (N
) atmosphere led to isolation of LCa(N
)CaL, ...which was characterized crystallographically. The N
- anion in this complex reacted in most cases as a very potent two-electron donor. Therefore, LCa(N
)CaL acts as a synthon for the low-valent Ca
complex LCa-CaL, which was the target of our studies. The N
- anion could also be protonated to diazene (N
H
) that disproportionated to hydrazine and N
The role of Ca d orbitals for N
activation is discussed.
The origin of the multiband activities (outbursts/flares) of blazars is still a heavily debated topic. Shock and magnetic reconnection have long been considered as possible triggers of the multiband ...activities. In this paper, we present an exploration of the origin of multiband activities for a high-redshift (z = 1.8385) flat-spectrum radio quasar PKS 1502+106. Utilizing multiband data from radio to γ-ray and optical polarization observations, we investigate two dramatic activities in detail: a γ-ray-dominated outburst in 2015 and an optical-dominated outburst in 2017. Our main results are as follows. (I) A fast γ-ray flare with a flux-doubling timescale as short as 1 hr in 2015 is discovered. Based on the variability timescale, the physical parameters of the flaring region (e.g., minimum Doppler factor, emission region size, etc.) are constrained. At the peak of the flare, the γ-ray spectrum hardens to Γγ = 1.82 0.04 and exhibits an obvious curvature/break characteristic that is caused by the typical "cooling break." Modeling of multiband spectral energy distributions reveal a very hard electronic energy spectrum with the electronic spectral index of 1.07 0.53. This result suggests that this fast γ-ray flare may be triggered by magnetic reconnection. (II) During the outburst in 2017, the degree of optical polarization and optical fluxes showed a very tight correlation. By analyzing the Stokes parameters of polarization observations, our results show that this outburst could be triggered by a transverse shock with a compression ratio of > 2.2, and the magnetic field intensity of the shock emission region is about 0.032 G.
In this paper, four kinds of hard coatings, TiN, CrN, TiAlN and CrAlN (with Al/Ti or Al/Cr atomic ratio around 1:1), were deposited on stainless steel substrates by a lateral rotating cathode arc ...technique. The as-deposited coatings were annealed in ambient atmosphere at different temperatures (500–1000 °C) for 1 h. The evolution of chemical composition, microstructure, and microhardness of these coatings after annealing at different temperatures was systematically analyzed by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and nanoindentation experiments. The oxidation behaviour and its influence on overall hardness of these four coatings were compared. It was found that the ternary TiAlN and CrAlN coatings have better oxidation resistance than their binary counterparts, TiN and CrN coatings. The Cr-based coatings (CrN and CrAlN) exhibited evidently better oxidation resistance than the Ti-based coatings (TiN and TiAlN). TiN coating started to oxidize at 500 °C. After annealing at 700 °C no N could be detected by EDX, indicating that the coating was almost fully oxidized. After annealed at 800 °C, the coating completely delaminated from the substrate. TiAlN started to oxidize at 600 °C. It was nearly fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 1000 °C. Both CrN and CrAlN started to oxidize at 700 °C. CrN was almost fully oxidized (with little residual nitrogen detected in the coating by EDX) and partially delaminated at 900 °C. The oxidation rate of the CrAlN coating is quite slow. After annealing at 1000 °C, only about 19 at.% oxygen was detected and the coating showed no delamination. The Ti-based (TiN and TiAlN) coatings were not able to retain their hardness at higher temperatures (≥
700 °C). On the other hand, the hardness of CrAlN was stable at a high level between 33 and 35 GPa up to an annealing temperature of 800 °C and still kept at a comparative high value of 18.7 GPa even after annealed at 1000 °C, indicating a very promising applicability of this coating for high speed dry machining and other applications under high temperature environments.
The impact of impurity ions on a pedestal has been investigated in the HL-2A Tokamak, at the Southwestern Institute of Physics, Chengdu, China. Experimental results have clearly shown that during the ...H-mode phase, an electromagnetic turbulence was excited in the edge plasma region, where the impurity ions exhibited a peaked profile. It has been found that double impurity critical gradients are responsible for triggering the turbulence. Strong stiffness of the impurity profile has been observed during cyclic transitions between the I-phase and H-mode regime. The results suggest that the underlying physics of the self-regulated edge impurity profile offers the possibility for an active control of the pedestal dynamics via pedestal turbulence.
It is prevailingly thought that estrogen signaling is not involved in development of estrogen receptor (ER)-negative breast cancer. However, there is evidence indicating that ovariectomy prevents the ...development of both ER-positive and -negative breast cancer, suggesting that estrogen signaling is involved in the development of ER-negative breast cancer. Previously, our laboratory cloned a variant of ER-α, ER-α36, and found that ER-α36 mediated nongenomic estrogen signaling and is highly expressed in ER-negative breast cancer cells. In this study, we found that ER-α36 was highly expressed in 10/12 cases of triple-negative breast cancer. We investigated the role of mitogenic estrogen signaling mediated by ER-α36 in malignant growth of triple-negative breast cancer MDA-MB-231 and MDA-MB-436 cells that express high levels of ER-α36 and found that these cells strongly responded to mitogenic estrogen signaling both in vitro and in vivo. Knockdown of ER-α36 expression in these cells using the small hairpin RNA method diminished their responsiveness to estrogen. ER-α36 physically interacted with the EGFR/Src/Shc complex and mediated estrogen-induced phosphorylation of epidermal growth factor receptor (EGFR) and Src. EGFR signaling activated ER-α36 transcription through an AP1 site in the ER-α36 promoter, and ER-α36 expression was able to stabilize EGFR protein. Our results, thus demonstrated that ER-α36 mediates nongenomic estrogen signaling through the EGFR/Src/ERK signaling pathway in ER-negative breast cancer cells and suggested that a subset of ER-negative breast tumors that expresses ER-α36, retains responsiveness to mitogenic estrogen signaling.
The Coronavirus disease 2019 (COVID-19) which outbroke in December 2019 is highly contagious with a low cure rate. In view of this, there is an urgent need to find a more appropriate therapeutic ...scheme against COVID-19. The study aimed to investigate whether lopinavir/ritonavir (LPV/r) in combination with other pneumonia-associated adjuvant drugs has a better therapeutic effect on COVID-19.
Totally 47 patients with COVID-19 infection who were admitted to Rui'an People's Hospital between January 22 and January 29, 2020 were collected. The patients were divided into the test group and the control group according to whether they had been treated with LPV/r or not during hospitalization. Patients in the test group were treated with LPV/r combined with adjuvant medicine, while those in the control group were just treated with adjuvant medicine. The changes of body temperature, blood routine and blood biochemistry between the two groups were observed and compared.
Both groups achieved good therapeutic effect with the body temperature of patients decreased gradually from admission to the 10th day of treatment. But the body temperature of patients in the test group decreased faster than that of the control group. Blood routine indexes showed that compared with the control group, the abnormal proportion of white blood cells, lymphocytes and C-reactive protein of the test group could be reduced to some extent. Blood biochemical indexes exhibited that the proportion of patients with abnormal alanine aminotransferase and aspartate aminotransferase in the test group were lower than the control group. The number of days for nCoV-RNA turning negative after treatment was significantly decreased in the test group than that in the control group.
Compared with the treatment of pneumonia-associated adjuvant drugs alone, the combination treatment with LPV/r and adjuvant drugs has a more evident therapeutic effect in lowering the body temperature and restoring normal physiological mechanisms with no evident toxic and side effects. In view of these conclusions, we suggested that the use of LPV/r combined with pneumonia-associated adjuvant drugs in the clinical treatment for patients with COVID-19 should be promoted.
The synchronization of geodesic acoustic modes (GAMs) and magnetic fluctuations is identified in the edge plasmas of the HL-2A tokamak. Mesoscale electric fluctuations (MSEFs) having components of a ...dominant GAM, and m/n=6/2 potential fluctuations are found at the same frequency as that of the magnetic fluctuations of m/n=6/2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m/n=6/2 magnetic fluctuations. The results indicate that GAMs and magnetic fluctuations can transfer energy through nonlinear synchronization. Such nonlinear synchronization may also contribute to low-frequency zonal flow formation, reduction of turbulence level, and thus confinement regime transitions.
We have developed a general two-step synthesis of large-scale arrays of one-dimensional (1D) nanostructured Co3O4 directly on various substrates. Throughout a controllable hydrothermal process using ...urea as mineralizer and hereafter with a postcalcination process under air atmosphere, Co3O4 1D nanostructure arrays have been grown firmly on insulating substrates, such as glass slides and ceramics, which is quite convenient for the construction of gas sensor devices without any extra electrode preparation process. Furthermore, this direct-growth approach can be readily extended to conductive substrates (ITO, Ti, Fe−Co−Ni alloy), and meanwhile due to the robust mechanical adhesion and one-dimensional carrier transportation architecture firmly contacted to the metal, the metal substrate-supported Co3O4 arrays could act as a promising electrode material and be straightforwardly integrated into electronic and electrochemical nanodevices.
Solid-lubricant MoS2 coatings have been successfully applied in high vacuum and aerospace environments. However, these coatings are very sensitive to water vapor and not suitable for applications in ...moist environments. In this work, Cr- and T-doped MoS2 composite coatings were developed. The results demonstrated that these composite coatings are promising for applications in high humidity environments. MoS2-Cr and MoS2-Ti composite coatings with different Cr or Ti content were deposited on high speed steel substrate by unbalanced magnetron sputtering. The composition, microstructure, and mechanical properties of the as-deposited MoS2-metal composite coatings were analyzed by energy dispersive analysis of X-ray (EDX), X-ray diffraction (XRD), and nanoindentation experiments. The tribological properties of the coatings were evaluated against an alumina ball under different relative humidity atmosphere using a ball-on-disc tribometer. The MoS2-Cr and MoS2-Ti coatings showed a maximum hardness of 7.5GPa and 8.4GPa at a dopant content of 16.6at.% Cr or 20.2at.% Ti, respectively. The tribological test results showed that, with a small amount of Cr and/or Ti doping, the tribological properties of MoS2 coatings under humid atmosphere could be significantly improved. The optimum doping level was found to be around 10at.% for both MoS2-Cr coatings and MoS2-Ti coatings to show the best tribological properties, with both the lowest friction coefficient and wear rate. The excellent tribological properties of the MoS2-Cr and MoS2-Ti coatings with an appropriate metal doping level in moist atmosphere are found due to their ability to form stable transfer layer on the surface of the counterbody, which supplies lubrication for the contact surface.
The dynamic features of the low-intermediate-high-(L-I-H) confinement transitions on HL-2A tokamak are presented. Here we report the discovery of two types of limit cycles (dubbed type-Y and type-J), ...which show opposite temporal ordering between the radial electric field and turbulence intensity. In type-Y, which appears first after an L-I transition, the turbulence grows first, followed by the localized electric field. In contrast, the electric field leads type-J. The turbulence-induced zonal flow and pressure-gradient-induced drift play essential roles in the two types of limit cycles, respectively. The condition of transition between types-Y and -J is studied in terms of the normalized radial electric field. An I-H transition is demonstrated to occur only from type-J.
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