In the study, the electrodeposition mechanism of Ni–Mo alloy was investigated. Potentiostatic deposition showed that the presence of MoO42− could reduce the deposition overpotential of Ni, and the ...deposition current efficiency of Ni–Mo alloy was lower than pure Ni deposition as the potential moved negatively. Cyclic Voltammetry (CV) indicated that both the first reduction peak for Ni deposition and the deposition peak of Ni–Mo alloy moved to more positive potentials as the content of Ni2+ increased, but the deposition peak of Ni–Mo alloy moved to more negative potentials as the content of MoO42− increased. The cathodic polarization curve on Rotating Disc Electrode (RDE) presented that Ni–Mo codeposition was controlled by charge transfer. The morphology, composition and structure of Ni–Mo alloy were characterized by SEM, EDS and XRD. The results showed the Ni–Mo alloy coatings exhibited a spherical and cauliflower-like pattern, having a considerably rougher surface, with nano-crystal structure when the elements composition was Ni80.14Mo19.59. The electrochemical activity for hydrogen evolution of Ni–Mo alloy was studied in 30 wt.% KOH at 25 °C using steady-state polarization and electrochemical impedance spectroscopy (EIS) methods. The results clearly demonstrated that an increase in the electrochemical activity for hydrogen evolution of the Ni–Mo alloy coating can be attributed both higher exchange current density and larger real electrode area.
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•The electrodeposition mechanism of Ni–Mo alloy was investigated.•The Ni80.14Mo19.59 alloy coatings exhibited a spherical and cauliflower-like pattern, with nano-crystal structure.•The Ni–Mo alloy had better catalytic activity for hydrogen evolution.
The electronic structures and magnetic properties of a new series of quaternary Heusler alloys CoFeScZ (Z=P, As, Sb) are investigated through first-principle calculations. CoFeScP is found to have ...half-metallic ferromagnetism with a large half-metallic gap of 0.60eV. The results show that both CoFeScAs and CoFeScSb are nearly half-metal under the equilibrium lattice constants. The change of the properties of CoFeScAs and CoFeScSb with pressure is investigated.
•Investigate a new series of quaternary Heusler alloys CoFeScZ (Z=P, As, Sb).•The band gap of the half-metal CoFeScP is very large.•Study the magnetic properties and electronic structure of CoFeScP under the equilibrium lattice constant.•Investigate the influence of pressure on the magnetic properties and electronic structure of CoFeScAs and CoFeScSb.
Alcohol addiction is a chronic neuropsychiatric disorder that represents one of the most serious global public health problems. Yet, currently there still lacks an effective pharmacotherapy. Omega‐3 ...polyunsaturated fatty acids (N‐3 PUFAs) have exhibited beneficial effects in a variety of neurological disorders, particularly in reversing behavioral deficits and neurotoxicity induced by prenatal alcohol exposure and binge drinking. In the present study, we investigated if fish oil, which is rich in N‐3 PUFAs, had beneficial effects on preventing relapse and alleviating withdrawal symptoms after chronic alcohol exposure. Our results demonstrated that fish oil significantly reduced the chronic alcohol exposure‐induced aberrant dendritic morphologic changes of the medium‐sized spiny neurons in the core and the shell of nucleus accumbens. This inhibited the expression of AMPAR2‐lacking AMPARs and their accumulation on the post synaptic membranes of medium‐sized spiny neurons and eventually alleviated withdrawal symptoms and alcohol dependence. Our study therefore suggests that N‐3 PUFAs are promising for treating withdrawal symptoms and alcohol dependence.
Fish oil reduced the aberrant dendritic morphologic changes in the core and shell of nucleus accumbens. It inhibited the expression of AMPAR2‐lacking AMPARs and their accumulation on the postsynaptic membranes. Also, it alleviated withdrawal symptoms and alcohol dependence.
Design of novel n‐type transparent conducting oxides beyond Sn‐doped In2O3 has stimulated extensive interest in the past decade. One of the approaches can be using transition metals (TMs) as dopants. ...In this article, using In2O3 as an example, it is shown that TM doping in oxides can be classified into three categories (type‐I, II, or III) based on their TM d‐orbital energy levels reference to the bottom of the conduction band of In2O3. It is found that although Mo is proposed to replace Sn as a promising TM donor to achieve higher carrier density in In2O3, it actually exhibits unusual dual‐doping behaviors, i.e., it can act as either a deep donor when it occupies the In 8b‐sites (type‐I) or shallow single donor when it occupies the In 24d‐sites (type‐II). The calculated ionization of Mo in In2O3 increases as the growth temperature increases, in good agreement with experimental observations but contradict to previous theoretical studies. It is also identified that Zr, Hf, and Ta (type‐III) are better potential donors than Mo and Sn in In2O3 for achieving higher carrier mobility and density. The analysis and approach can also be used to improve the doping performance in other oxides.
A general rule to classify the doping behaviors of transition‐metal atoms in In2O3 into three different types (type‐I, II, or III) is found. Based on this understanding it is identified that Zr, Hf, and Ta (type‐III) are better potential donors than Mo and Sn in In2O3 for achieving higher carrier mobility and density.
Reverse transcriptase (RT) of human immunodeficiency virus (HIV)-1 plays a key role in initiating viral replication and is an important target for developing anti-HIV drugs. Our previous study showed ...that two mutations (Y271A and I274A) in the turn RT (Gln(269)-Arg(277)) abrogated viral replication, but the replication capacity and RT activity was discordant. In this study, we further investigated why alanine substitutions at these two sites would affect viral replication. We found that both RT activity and RT protein were almost undetectable in viral particles of these two mutants, although the Pr160(gag-pol) mutants were properly expressed, transported and incorporated. Using protease inhibition assay, we demonstrated a correlation between the degradation of the RT mutants and the activity of viral protease. Our native gel analysis indicated that the mutations at 271 and 274 amino acids might cause conformational changes, leading to the formation of higher order oligomers instead of dimers, resulting in increased protein instability and susceptibility to viral protease. Thus, residues 271 and 274 are critical to RT stability and resistance to viral protease. The conservation of the two amino acid residues among different strains of HIV-1 lent further support to this conclusion. The knowledge gained here may prove useful in drug design.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The preparation of polyolefins using controlled radical polymerisation (CRP) has long been a goal of polymer chemistry, but is hampered by the instability of olefin radicals. Herein we propose a ...simple strategy for the preparation of well-defined polyolefins such as polypropylene, by post-modification of poly(acrylic acid) with dialkylzinc reagents. The starting polymers can be readily synthesised by existing CRP techniques to almost any desired length and architecture. After activation of the carboxylic acid side chain and reaction with the dialkylzinc, a new C–C bond is formed between the alkyl group and the backbone carbon, and the carboxylic acid functionality is lost as CO 2 . We used this strategy to prepare well-defined polyolefins with methyl, ethyl, propyl and butyl side chains. As the dialkylzinc reagents are unreactive towards esters we were also able to use this approach to synthesise and self-assemble a range of PEGMEA-olefin block copolymers.
The induced earthquake recently has gained an increasing public awareness of environmental and safety issue. The earthquakes associated with fluid injection and extraction, reservoir impoundment and ...mining/rock removal have been extensively reported. Here, we reviewed injection induced earthquakes and their mechanisms from a view of rock mechanics. This review begins by briefly introducing the classification and the state-of-the-art research of induced earthquakes. From a view of rock mechanics, three fundamental mechanisms of induced earthquakes, i.e., pore pressure increase, stress change, and change in coefficient of friction, are introduced in details. Firstly, we discussed pore pressure increase due to fluid injection and reservoir impoundment, and explained earthquakes caused by fluid injection and related to reservoirs according to the Mohr–Coulomb failure criterion and effective stress law in the saturated rock. Secondly, we discussed stress change resulting from fluid extraction, temperature change, reservoir loading and quarry unloading. Thirdly, we investigated factors determining coefficient of friction, i.e., mineralogy, fluid pressure and temperature. Moreover, it is a remarkable fact that additional physical or chemical effects of fluids may lead to weakening of materials in fault zones owing to stress corrosion and stable slip, according to the rate and state friction law. Finally, we summarized and compared mechanisms of induced earthquakes that occurred in a variety of past human activities and projects, and recommended future potential means and scopes to investigate the mechanism of induced earthquakes.
•Theoretical analyses find forcing more side-curl on chip is positive on its breaking.•Block surface is proposed on secondary cutting edge of step drill for breaking chip.•Chip breaking and quality ...improvement are achieved in one-shot drilling CFRP/Al.•Interactions between chips and CFRP/Al are revealed under different chips evacuating.
CFRP/Al stacks are popular for aerospace structures which require one-shot drilling thousands of stack holes within strict damage tolerance. However, CFRP is susceptible to cutting damages; the evacuation of Al chips through the upper CFRP may also cause unexpected damages even with a preferable step drill bit, of which second step faces the challenge of breaking chips due to its space and cutting angle limitations. This article proposes a novel structure on the second step of a step drill bit to effectively break the Al chips and reduce the chip-induced damage in one-shot drilling of CFRP/Al stack. The cutting chip generation/motion of the second step is analyzed, and it is found that adding a block surface beside the rake surface to restrain the side-curl of the chips could increase the surface strain of the chip and possibly break it. More importantly, the block surface is an additional structure beside the secondary cutting edge, which will neither affect its cutting angle nor be limited by space. Then a novel chip breaking structure based on the block surface is invented at the inner side on the rake surface of the secondary cutting edge. Comparative experiments are carried out for one-shot drilling of CFRP/Al, and the interactions between chips and CFRP/Al are revealed. With the novel structure, effective Al chip breaking and significant improvement of CFRP drilling quality are achieved.
The cavitation erosion of materials in sandy water is a very important topic in water conservancy and industrial production. In this paper, an ultrasonic vibration cavitation apparatus and underwater ...low-voltage electric discharge device are applied to investigate the erosion characteristics of 6063 aluminium specimens in sandy water with different sediment sizes and concentrations and the underlying mesoscale damage mechanism. The results show that the specimen damage gradually increases as the mean sand particle size increases. When the mean sand particle size is less than 0.120 mm, the resulting damage is lower than that in pure water. When the sand concentration is less than 10 kg/m3, the resulting damage is not very different from that in pure water. As the sediment concentration in the sand-water mixture increases, the influence of the sand particles on cavitation gradually increases. The bubble-particle interaction experiments reveal that the cavitation bubbles that interact with multiple small spherical particles show obvious non-spherical morphology and prolong the collapse time during the first collapse phase and reduce the collapse strength. The results of the bubble-particle interaction experiments verify the erosion characteristics obtained from the ultrasonic vibration cavitation test, which is significant for elucidating the damage mechanics of specimens in sandy water.
•The critical sediment size is approximately 0.120 mm according to the mass loss.•The sediment concentration within 10 kg/m3 rarely affect the damage of specimens.•Discussed the morphology and collapse time in three bubble-particle interactions.•The collapse strength in three bubble-particle interactions is demonstrated.
Image retrieval performance can be improved by training a convolutional neural network (CNN) model with annotated data to facilitate accurate localization of target regions. However, obtaining ...sufficiently annotated data is expensive and impractical in real settings. It is challenging to achieve accurate localization of target regions in an unsupervised manner. To address this problem, we propose a new unsupervised image retrieval method named unsupervised target region localization (UTRL) descriptors. It can precisely locate target regions without supervisory information or learning. Our method contains three highlights: 1) we propose a novel zero-label transfer learning method to address the problem of co-localization in target regions. This enhances the potential localization ability of pretrained CNN models through a zero-label data-driven approach; 2) we propose a multiscale attention accumulation method to accurately extract distinguishable target features. It distinguishes the importance of features by using local Gaussian weights; and 3) we propose a simple yet effective method to reduce vector dimensionality, named twice-PCA-whitening (TPW), which reduces the performance degradation caused by feature compression. Notably, TPW is a robust and general method that can be widely applied to image retrieval tasks to improve retrieval performance. This work also facilitates the development of image retrieval based on short vector features. Extensive experiments on six popular benchmark datasets demonstrate that our method achieves about 7% greater mean average precision (mAP) compared to existing state-of-the-art unsupervised methods.
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