Aluminum bipolar plates offer good mechanical performance and availability for mass production while allow up to 65% lighter than stainless steel. To improve the corrosion resistance and surface ...electrical conductivity of aluminum bipolar plates, several coatings, including TiN, CrN, C, C/TiN and C/CrN, are deposited on aluminum alloy 5052 (AA-5052) by close field unbalanced magnetron sputter ion plating. Scanning electron microscope (SEM) results show that the coatings containing carbon layer are denser than TiN and CrN. Although the potentiodynamic test results show improved corrosion resistance by all the coatings, the potentiostatic test results reveal different stability of these coatings in PEMFC environments. Comparing the SEM images of these coatings after potentiostatic test, C/CrN multilayer coating exhibits the best stability. C/CrN multilayer coated AA-5052 has the lowest metal ion concentration after potentiostatic test, being 11.12 ppm and 1.29 ppm in PEMFC cathodic and anodic environments, respectively. Furthermore, the interfacial contact resistance (ICR) of the bare AA-5052 is decreased from 61.58 mΩ-cm2 to 4.08 mΩ-cm2 by C/CrN multilayer coating at the compaction force of 150 N-cm−2. Therefore, C/CrN multilayer coating is a good choice for surface modification of aluminum bipolar plate.
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•C/TiN and C/CrN multilayer coatings are denser than single-layer coatings.•C/CrN multilayer coating has the best corrosion resistance among these coatings.•C/CrN has the lowest ICR of 4.08 mΩ-cm2 at compaction force of 150 N-cm−2.•The corrosion in cathode environment is much more serious than that in anode one.
Electromagnetically induced transparency and absorption of a monochromatic light controlled by a radio frequency field in the cold multi-Zeeman-sublevel atoms are theoretically investigated. These ...Zeeman sublevels are coupled by a radio frequency （RF） field. Both electrom~gnetically induced transparency and electromagnetically induced absorption can be obtained by tuning the frequency of RF field for both the linear polarization and elliptical polarization monochromatic lights. When the transfer of coherence via spontaneous emission from the excited state to the ground state is considered, electromagnetically induced absorption can be changed into electromagnetically induced transparency with the change of intensity of radio field. The transparency windows controlled by the RF field can have potential applications in the magnetic-field measurement and quantum information processing.
High electrical conductivity and corrosion resistance are central to advances in wider application of metallic bipolar plates in polymer electrolyte membrane fuel cell (PEMFC). In this study, ...C/Cr-Ti-N multilayer coatings are deposited by physical vapor deposition and the effect of Cr:Ti ratio on the corrosion resistance and interfacial contact resistance (ICR) are systematically investigated. Scanning electron microscopy (SEM) result shows that the carbon layer is compact and uniform. Excellent corrosion resistance of 0.127 mu A cm-2 current density at operating voltage in PEMFC cathode environment and low ICR of 2.03 m Omega -cm2 at compaction force of 150 N cm-2 are achieved when Cr:Ti ratio is 2:4 and 3:3, respectively. The significant enhancement in surface conductivity is probably because that the current comes from carbon paper is homogenized by two electrically conductive layers and flows to the passive film with much more contact area. After polarization, ICR increase to 3.07 m Omega -cm2 and 3.02 m Omega -cm2 in the simulated PEMFC cathode and anode environment, respectively. However, the Raman spectroscopy results disclose that the bonding type of top carbon film before and after polarization shows little difference. The results indicate that C/Cr-Ti-N multilayer coating with Cr:Ti ratio of 2:4 achieves the optimal composition.
It remains unclear whether conservative treatment should be used to treat the common undisplaced femoral neck fractures that develop in the elderly. Herein, we systematically review the rates of ...union and avascular necrosis after conservative and surgical treatment of undisplaced femoral neck fractures.
We searched the EMBASE, PubMed, OVID, Cochrane Library, Web of Science, and Scopus databases for randomized controlled trials or observational studies that assessed the outcomes of conservative or surgical treatments of undisplaced femoral neck fractures. No language or publication year limitation was imposed. Statistical analyses were performed with the aid of the chi-squared test. We evaluated the quality of each publication and the risk of bias.
Twenty-nine studies involving 5071 patients were ultimately included; 1120 patients were treated conservatively and 3951 surgically. The union rates were 68.8% (642/933) and 92.6% (635/686) in the former and latter groups, respectively (p < 0.001). The avascular necrosis rate in the conservatively treated group was 10.3% (39/380), while it was 7.7% (159/2074) in the surgically treated group (p = 0.09).
Surgery to treat undisplaced femoral neck fractures was associated with a higher union rate and a tendency toward less avascular necrosis than conservative treatment.
Amorphous carbon (a-C) film about 3
μm in thickness is coated on 316L stainless steel by close field unbalanced magnetron sputter ion plating (CFUBMSIP). The AFM and Raman results reveal that the a-C ...coating is dense and compact with a small size of graphitic crystallite and large number of disordered band. Interfacial contact resistance (ICR) results show that the surface conductivity of the bare SS316L is significantly increased by the a-C coating, with values of 8.3–5.2
mΩ
cm
2 under 120–210
N/cm
2. The corrosion potential (
E
corr) shifts from about −0.3
V vs SCE to about 0.2
V vs SCE in both the simulated anode and cathode environments. The passivation current density is reduced from 11.26 to 3.56
μA/cm
2 with the aid of the a-C coating in the simulated cathode environment. The a-C coated SS316L is cathodically protected in the simulated anode environment thereby exhibiting a stable and lower current density compared to the uncoated one in the simulated anode environment as demonstrated by the potentiostatic results.
This paper presents a new IndRNN-based deep attention model, termed DA-IndRNN, for skeleton-based action recognition to effectively model the fact that different joints are usually of different ...degrees of importance to different action categories. The model consists of (a) a deep IndRNN as the main classification network to overcome the limitation of a shallow RNN network in order to obtain deeper and longer features, and (b) a deep attention network with multiple fully connected layers to estimate reliable attention weights. To train the DA-IndRNN, a new triplet loss function is proposed to guide the learning of the attention among different action categories. Specifically, this triplet loss enforces intra-class attention distances to be smaller than inter-class attention distances and at the same time to allow multiple attention weight patterns to exist for the same class. The proposed DA-IndRNN can be trained end-to-end. Experiments on the widely used datasets, including the NTU RGB + D dataset and UOW Large-Scale Combined (LSC) Dataset, have demonstrated that the proposed method can achieve better and stable performance than the state-of-the-art attention models.
The response of tidal range in tidal marshes under sea‐level rise (SLR) is essential to the marsh resilience, but how tidal ranges respond to different marsh evolutions remains unclear. Here, we show ...the existence of bifurcate responses of tidal range to SLR using both numerical model and theoretical analyses. The tidal range tends to increase if marsh accretion keeps pace with SLR; otherwise, the tidal range tends to decrease. As tidal range plays the key role in marsh evolution, the interactions between changing tidal range and marsh evolution lead to positive feedback on marsh resilience. If the marsh accretion can keep up with the SLR, the increase in the tidal range can enhance marsh resilience to SLR. If the marsh cannot keep up, the decrease in the tidal range may further threaten the marsh resilience or even lead to marsh retreat.
A series of new 1‐phenylsulphonyl‐2‐(1‐methylindol‐3‐yl)‐benzimidazole derivatives were designed, synthesized and evaluated as potential inhibitors of tubulin polymerization and anthropic cancer cell ...lines. Among them, compound 33 displayed the most potent tubulin polymerization inhibitory activity in vitro (IC50 = 1.41 μM) and strong antiproliferative activities against A549, Hela, HepG2 and MCF‐7 cell lines in vitro with GI50 value of 1.6, 2.7, 2.9 and 4.3 μM, respectively, comparable with the positive control colchicine (GI50 value of 4.1, 7.2, 9.5 and 14.5 μM, respectively) and CA‐4 (GI50 value of 2.2, 4.3, 6.4 and 11.4 μM, respectively). Simultaneously, we evaluated that compound 33 could effectively induce apoptosis of A549 associated with G2/M phase cell cycle arrest. Immunofluorescence microscopy also clearly indicated compound 33 a potent antimicrotubule agent. Docking simulation showed that compound 33 could bind tightly with the colchicine‐binding site and act as a tubulin inhibitor. Three‐dimensional‐QSAR model was also built to provide more pharmacophore understanding that could be used to design new agents with more potent tubulin assembling inhibitory activity in the future.
Crystal structure diagram of compound 15. 3D diagram of the interaction between compound 33 and the colchicine‐binding site. Compounds of novel 1‐phenylsulphonyl‐2‐(1‐methylindol‐3‐yl)‐benzimidazole derivatives containing different substituent groups were designed, synthesized and evaluated for their inhibitory activity against tubulin polymerization and cancer cell growth. Docking simulation and the QSAR study were conducted.
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