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The research of high-performance flexible supercapacitors is urgent due to the rapid development of wearable and portable electronics. The key challenge is the preparation of flexible electrodes with high areal capacitance since electrodes are the most important part of supercapacitors. Compared to those conventional electrodes loading with typical flexible substrates such as textile, PET, paper et al, free-standing electrodes have many advantages such as more efficient capacity contribution, solidly embedded active materials and thinner thickness. Herein, we have successfully fabricated a novel sandwich-like structure free-standing MoO3-rGO (reduced graphene oxide) composite film electrode for flexible supercapacitors using simple vacuum filtration method followed by HI reduction process. The obtained MoO3-rGO composite film electrode shows excellent electrochemical performance, whose areal specific capacitance reaches 8972 mF·cm-2 (1.5 mA·cm-2). Here, MoO3 provides pseudocapacitance and rGO provides double-layer capacitance. After cycling for 2000 cycles, the capacity retention is 86.7%, showing good cycle stability. Besides, the as-prepared composite film has good flexibility and will not break easily during following bending, rolling, folding or twisting steps. This study has been approved to be an important step for the high-performance electrode design for free-standing flexible supercapacitors.
Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88) presented a critique of our recently published paper in Cell Reports entitled ‘Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets’ (Lam et al., Cell Reports, Vol. 21, 2017, 2597–2613). Specifically, Hill offered several interrelated comments suggesting potential problems with our use of a new analytic method called Multi-Trait Analysis of GWAS (MTAG) (Turley et al., Nature Genetics, Vol. 50, 2018, 229–237). In this brief article, we respond to each of these concerns. Using empirical data, we conclude that our MTAG results do not suffer from ‘inflation in the FDR [false discovery rate]’, as suggested by Hill (Twin Research and Human Genetics, Vol. 21, 2018, 84–88), and are not ‘more relevant to the genetic contributions to education than they are to the genetic contributions to intelligence’.
It was reported that high blood cholesterol levels increased the susceptibility to mitochondrial dysfunction. This study hypothesized that the gestational hypercholesterolemia (HC) could induce the mitochondrial dysfunction in term human placenta. The eligible pregnant women were recruited from Xuanwu Hospital in Beijing during their first prenatal visit (before their 10th week of pregnancy). In total, 19 pregnant women whose serum total cholesterol levels were higher than 7.25 mm at third trimester (measured at 36–38 weeks) were selected as gestational HC. Other 19 pregnant women with normal cholesterol level matched with age, pre-gestational body mass index, and the neonatal gender were included as the control group. Full-term placenta samples were collected. The mitochondrial DNA (mtDNA) copy number, messenger RNA (mRNA) expression of cytochrome c oxidase subunit I, adenosine triphosphate monophosphatase 6 (ATP6ase), citrate synthase, peroxisome proliferator-activated receptor-γ (PPARγ) co-activator 1α, PPARγ co-activator 1β and estrogen-related receptor-α, and the activity of mitochondrial respiratory chain enzyme complex were measured. Pregnancy outcomes were obtained by extraction from medical records and the labor ward register. The results showed that only placental mtDNA copy number and mRNA expression of ATP6ase were significantly decreased in HC group. No significant differences were detected of other measurements between the two groups. These findings indicated that gestational HC might not induce the damage of placental function seriously.
Surface exfoliation was observed on single-crystal silicon surface under the action of compressed plasma flow (CPF). This phenomenon is mainly attributed to the strong transient thermal stress impact induced by CPF. To gain a better understanding of the mechanism, a micro scale model combined with thermal conduction and linear elastic fracture mechanics was built to analyze the thermal stress distribution after energy deposition. After computation with finite element method, J integral parameter was applied as the criterion for fracture initiation evaluation. It was demonstrated that the formation of surface exfoliation calls for specific material, crack depth, and CPF parameter. The results are potentially valuable for plasma/matter interaction understanding and CPF parameter optimization.
Low-field magnetic stimulation (LFMS) has mood-elevating effect, and the increase of brain-derived neurotrophic factor (BDNF) is associated with antidepressant treatment. We evaluated the effects and association with BDNF of rhythmic LFMS in the treatment of major depressive disorder (MDD).
A total of 22 MDD patients were randomized to rhythmic alpha stimulation (RAS) or rhythmic delta stimulation (RDS), with 5 sessions per week, lasting for 6 weeks. Outcomes assessments included the 17-item Hamilton Depression Rating Scale (HAMD–17), the Hamilton Anxiety Rating Scale (HAMA), and the Clinical Global Impressions–Severity scale (CGI–S) at baseline and at weeks 1, 2, 3, 4, and 6. Serum BDNF level was measured at baseline and at weeks 2, 4, and 6.
HAMD–17, HAMA, and CGI–S scores were significantly reduced with both RAS and RDS. RAS patients had numerically greater reductions in HAMD–17 scores than RDS patients (8.9 ± 7.4 vs. 6.2 ± 6.2, effect size [ES]=0.40), while RDS patients had greater improvement in HAMA scores (8.2 ± 8.0 vs. 5.3 ± 5.8, ES=0.42). RAS was associated with clinically relevant advantages in response (54.5% vs. 18.2%, number-needed-to-treat [NNT]=3) and remission (36.4% vs. 9.1%, NNT=4). BDNF increased significantly during the 6-week study period (p<0.05), with greater increases in RAS at weeks 4 and 6 (ES=0.66—0.76) and statistical superiority at week 2 (p=0.034, ES=1.23). Baseline BDNF in the 8 responders (24.8±9.0 ng/ml) was lower than in the 14 nonresponders (31.1±7.3 ng/ml, p=0.083, ES=–0.79), and BDNF increased more in responders (8.9±7.8 ng/ml) than in nonresponders (1.8±3.5 ng/ml, p=0.044). The change in BDNF at week 2 was the most strongly predicted response (p=0.016).
Rhythmic LFMS was effective for MDD. BDNF may moderate/mediate the efficacy of LFMS.
As the strong thermal effect in the surface, intense pulsed ion beam (IPIB) has been extensively used in material surface modification. The ablation is an important part in the interaction process between IPIB and material. In order to investigate the ablation mechanism, combined with IPIB dynamic energy spectrum and infrared imaging diagnostic results, a two-dimensional axisymmetric heat conduction model considering the effect of ablated material was constructed to describe the ablation process and calculate the lost mass of the targets. The influences of beam parameters and ablated matter on the ablation rate were discussed. The experimental and simulative results of ablation threshold and mass were compared.
As a kind of flash heat source, intense pulsed ion beam (IPIB) can be used for material surface modification. The ablation effect has important influence on interaction between IPIB and material. Therefore, the understanding of ablation mechanism is of great significance to IPIB application. In this work, pure zinc targets were irradiated and ablated by IPIB. In the ablation process under the different ion beam energy densities, the ablation products were collected by a monocrystalline silicon substrate. By analyzing the ablation products with scanning electron microscope and energy-dispersive spectrometer, the surface morphology, and the spatial distribution of ablation products quantity were obtained. The results are useful for clearing the ablation process and the influence of beam parameter on the ablation effect.
As the energy spread of intense pulsed electron beams (IPEB) strongly influences the irradiation effects, it has been of great importance to characterize the IPEB energy spectrum. With the combination of Child–Langmuir law and Monte Carlo simulation, the IPEB energy spectrum has been obtained in this work by transformation from the accelerating voltage applied to the diode. To verify the accuracy of this simple algorithm, a magnetic spectrometer with an imaging plate was designed to test the IPEB energy spectrum. The measurement was completed with IPEB generated by explosive emission electron diode, the pulse duration, maximum electron energy, total beam current being 80 ns, 450 keV, and 1 kA, respectively. The results verified the reliability of the above analysis method for energy spectrum, which can avoid intercepting the beam, and at the same time significantly improved the energy resolution. Some calculation and experimental details are discussed in this paper.
The effect of nitrogen gas addition in Ar-based double-layer shielding gas on the impact toughness of welded ultra-ferritic stainless steel during an autogenous gas tungsten arc welding (GTAW) process was investigated. The nitrogen behavior was proposed. The microstructure, mechanical properties, and fracture surface morphology of the weld metals have been evaluated. More equiaxed crystals, refined grain, narrow HAZ width, and increased microhardness were produced with nitrogen addition. Experimental findings indicated that nitrogen diffused into HAZ and dissolved into weld pool. The solute distribution was changed thus bringing significant constitutional supercooling and decreased temperature gradient of weld pool, which contributed to fine microstructure. Impact toughness at room temperature was enhanced from 2J to 9J (welds), 5J–13J (HAZ). Ductile fracture zone was produced about 0.3–0.5 mm thickness distance from the weld surface. A significant increased impact toughness of weld metal was due to the refinement of microstructure and element addition.
Declines in populations of the Critically Endangered Spoon-billed Sandpiper Calidris pygmaeus have been rapid, with the breeding population now perhaps numbering fewer than 120 pairs. The reasons for this decline remain unresolved. Whilst there is evidence that hunting in wintering areas is an important factor, loss of suitable habitat on passage and wintering areas is also of concern. While some key sites for the species are already documented, many of their wintering locations are described here for the first time. Their wintering range primarily stretches from Bangladesh to China. Comprehensive surveys of potential Spoon-billed Sandpiper wintering sites from 2005 to 2013 showed a wide distribution with three key concentrations in Myanmar and Bangladesh, but also regular sites in China, Vietnam and Thailand. The identification of all important non-breeding sites remains of high priority for the conservation of the species. Here, we present the results of field surveys of wintering Spoon-billed Sandpipers that took place in six countries between 2005 and 2013 and present species distribution models which map the potential wintering areas. These include known and currently unrecognised wintering locations. Our maximum entropy model did not identify any new extensive candidate areas within the winter distribution, suggesting that most key sites are already known, but it did identify small sites on the coast of eastern Bangladesh, western Myanmar, and the Guangxi and Guangdong regions of China that may merit further investigation. As no extensive areas of new potential habitat were identified, we suggest that the priorities for the conservation of this species are habitat protection in important wintering and passage areas and reducing hunting pressure on birds at these sites.
An evaluation method named vague set is proposed to describe the suitability of a geomagnetic map. It is based on the Fuzzy Decision Making (FDM) method, and overcomes the FDM model's shortcomings that favouring and opposing content cannot be taken into account simultaneously. The membership function and non-membership function are used to define the influence of the geomagnetic map parameters on map suitability, including standard deviation, information entropy, roughness and slope variance. The weight of each geomagnetic map parameter is calculated by establishing an optimisation model. Vague set data are divided into four types after classification, and Weighted Score Function Values (WSFVs) of matching areas are obtained by using the Weighted Score Function (WSF) method. Then, WSFV of each matching area are compared to select an optimal area. Simulation results demonstrate that geomagnetic map suitability is positively proportional to the function value, and matching error is negatively proportional to the WSFV of the matching area.
This paper presents semiparametric identification results for the Rust (1994) class of discrete choice dynamic programming (DCDP) models. We develop sufficient conditions for identification of the deep structural parameters for the case where the per-period utility function ascribed to one choice in the model is parametric but the distribution of unobserved state variables is nonparametric. The proposed identification strategy does not rely on availability of the terminal period data and can therefore be applied to infinite horizon structural dynamic models. Identifying power comes from assuming that the agent’s per-period utilities admit continuous choice-specific state variables that are observed with sufficient variation and satisfy certain conditional independence assumptions on the joint time series of observables. These conditions allow us to formulate exclusion restrictions for identifying the primitive structural functions of the model.
A model for predicting the austenite grain growth during a common heating process including continuous and isothermal heating processes in medium carbon alloy steel 42CrMo was developed. The isothermal austenite grain growth kinetics were studied with conditions involving soaking time and soaking temperature. The time exponent n in the model was obtained considering the influence of the initial grain size rather than simply utilizing Beck’s equation. The results showed that the value of the time exponent n is 3.55 ± 0.30 when the temperature is above 1000 °C, while the value is 8.33 when the temperature is below 1000 °C. When the temperature is below 1000 °C, the pinning effect of carbides contributes to the higher value of the time exponent. Based on the isothermal model and the rule of additivity, a model for predicting the grain growth occurring during continuous heating was proposed. A reasonable agreement between the calculations and experimental measurements of grain size was obtained. According to the model, the effect of the initial austenite grain size on the final austenite grain size during induction quenching was analyzed. The initial austenite grain size has a significant effect on the final austenite grain size. In order to obtain a refined quenched microstructure, it is necessary to refine the microstructure at room temperature.
Lutein and zeaxanthin are thought to decrease the incidence of age-related macular degeneration (AMD); however, findings have been inconsistent. We conducted a systematic literature review and meta-analysis to evaluate the relationship between dietary intake of lutein and zeaxanthin and AMD risk. Relevant studies were identified by searching five databases up to April 2010. Reference lists of articles were retrieved, and experts were contacted. Literature search, data extraction and study quality assessment were performed independently by two reviewers and results were pooled quantitatively using meta-analysis methods. The potential sources of heterogeneity and publication bias were also estimated. The search yielded six longitudinal cohort studies. The pooled relative risk (RR) for early AMD, comparing the highest with the lowest category of lutein and zeaxanthin intake, was 0·96 (95 % CI 0·78, 1·17). Dietary intake of these carotenoids was significantly related with a reduction in risk of late AMD (RR 0·74; 95 % CI 0·57, 0·97); and a statistically significant inverse association was observed between lutein and zeaxanthin intake and neovascular AMD risk (RR 0·68; 95 % CI 0·51, 0·92). The results were essentially consistent among subgroups stratified by participant characteristics. The findings of the present meta-analysis indicate that dietary lutein and zeaxanthin is not significantly associated with a reduced risk of early AMD, whereas an increase in the intake of these carotenoids may be protective against late AMD. However, additional studies are needed to confirm these relationships.
In this paper, we study the surfactant capability of In for the growth of AlGaN/GaN heterostructures by plasma-assisted molecular beam epitaxy. Growth conditions were determined to have a self-regulated 1×1 In adlayer on AlxGa1-xN (0001). The presence of this In film favors two dimensional growth of AlGaN under stoichiometric conditions, and inhibits the formation of metal droplets on the surface. The quality of these layers was assessed by high resolution X-ray diffraction, atomic force microscopy and photoluminescence.
Epitaxial growth of quaternary AlGalnN compounds by plasma-assisted molecular beam epitaxy has been demonstrated. Two-dimensional growth is achieved under In excess, with a monolayer of In segregating at the growth front. The maximum In incorporation is significantly affected by the substrate temperature and the Al mole fraction of the alloy. This behavior has been attributed to the enhancement of In segregation due to the high binding energy of A1N compared to InN and GaN.
For embedded DRAM (E-DRAM) devices with feature sizes of 0.25 µm and beyond, contact processes with low contact resistance and low junction leakage current are required. The contact etch process needs to etch through multi-layer structures with SiO2, SiON/SiN layers and stop on Ti-polycide gate and Ti-salicide active regions at the same time. The key issues include high selectivity to TiSix, vertical profile, complete removal of SiON/SiN cap layer and no polymer residues. In this paper, multi-layer contact etching without attacking TiSix is reported. Using new process chemistry, the new contact etch process has been demonstrated for the manufacturing of 0.25 µm E-DRAM and beyond.
This paper summarises our recent cyclic nanoindentation experiment studies on a range of materials including single crystal and nanocrystalline copper, single crystal aluminium and bulk metallic glasses with different glass transition temperatures. The unloading and reloading processes of the nanoindentation curves have been analysed. The reverse plasticity will be discussed in the context of plastic deformation mechanisms involved. The effect of loading rates on the mechanical properties of materials upon cyclic loading will also be discussed.
The microstructure and mechanical properties of nanocrystalline copper with grain size ranging from 50 nm to 80 nm have been investigated. Thin films of nanocrystalline copper were electrodeposited from an additive-free acidified copper sulphate solution at room temperature by employing constant current at different current density magnitudes between 20 and 80 mA/cm2. Both austenitic and ferritic steel substrates with the same surface finishing conditions have been used for the deposition. The microstructure of the thin films has been further studied using electron microscopy techniques, and the mechanical properties using nanoindentation technique. The nanoindentation study was carried out on both the plan view and cross-sectional directions to study the isotropy characteristic of the copper film. It has been noted that both the modulus and hardness measured following the Oliver-Pharr scheme show an apparent indentation size effect tested on the cross-sectional sample.
The thermal effect on the nanofluidic behaviors in a nanoporous silica gel is investigated experimentally. When a nanoporous silica gel is modified by silyl groups, its surface becomes hydrophobic. A sufficiently high external pressure must be applied to overcome the capillary effect; otherwise liquid infiltration could not occur. The formation and the disappearance of a solid–liquid interface are employed for energy storage or dissipation. When the hydrophobic surface of nanoporous silica gel is decomposed at various temperatures, the organic surface layers can be deactivated. As a result, the degree of hydrophobicity, which can be measured by the liquid infiltration pressure, is lowered. The infiltration and defiltration behaviors of liquid are dependent on the controlled by the decomposition-treatment temperature.