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In this study, Mg-substituted tricalcium phosphate (Mg-TCP) nanoparticles were synthesized by hydrothermal reactions of Mg-calcite mesocrystals from echinoderm skeletons. Following the biomineralization of echinoderms, Mg-calcite powder was synthesized via the solid-state transition of Mg-amorphous calcium carbonate prepared by a wet-chemical precipitation method, which can also be used to fabricate Mg-TCP. We illustrated that Mg-calcite with a certain level of Mg substitution led to the formation of Mg-TCP through the ion-exchange reactions in the hydrothermal system. Therefore, this study provides a new pathway for the synthesis of Mg-TCP nanoparticles.
Direct determination of barrier height (ΦBH) value between Ir and single crystal (001) hydrogen-terminated diamond with lightly boron doped has been performed using x-ray photoelectron spectroscopy technique. 70 nm Ir islands were formed on hydrogen-terminated diamond surface using anodic aluminum oxide. The ΦBH value for Ir/hydrogen-terminated diamond was −0.43 ± 0.14 eV, indicating that Ir was a suitable metal for ohmic contact with hydrogen-terminated diamond. The band diagram of Ir/hydrogen-terminated diamond was obtained. The experimental ΦBH was compared with the theoretical ΦBH in this work.
Insurance companies often follow highly correlated investment strategies. As major investors in corporate bonds, their investment commonalities subject investors to fire sale risk when regulatory restrictions prompt widespread divestment of a bond following a rating downgrade. Reflective of fire sale risk, the clustering of insurance companies in a bond has significant explanatory power for yield spreads, controlling for liquidity, credit risk, and other factors. The effect of insurer clustering on bond yield spreads is more evident for bonds held to a greater extent by capital-constrained insurance companies, those with ratings closer to National Association of Insurance Commissioners risk categories with larger capital requirements, and during the financial crisis.
High-entropy ceramic (HEC) films refer to the carbide, boride, oxide, or nitride films of the high-entropy alloy, which have potential applications under high temperatures. In this study, we fabricated the HEC NbTiAlSiZrNx films using magnetron sputtering under various deposition atmospheres. The phase structure evolution and the mechanical properties of three HEC films under high temperatures were investigated. The HEC films demonstrated good thermal stability as well as high hardness. After annealing for 24 h at 700 °C, the films remained in an amorphous phase without obvious crystallization, and the hardness of the films declined. Nanocrystallizations occurred in films deposited at a nitrogen flow rate of 4 sccm and 8 sccm after annealing for 30 min at 900 °C and exhibited an face-centered cubic structure. HEC NbTiAlSiZrNx films have potential applications as protective coatings under high temperatures.
The phase stability, equilibrium lattice parameters, mechanical properties, and chemical bonding of M2B and M2B0.75C0.25 (M = Fe, Cr, W, Mo, Mn) were studied using first-principles calculations within density functional theory. These compounds are thermodynamic stability structures, and the M2B0.75C0.25 stability is worse than that of M2B. The equilibrium lattice parameters are consistent with other available experimental and theoretical data. Stress–strain and Voigt–Reuss–Hill approximations were used to estimate the elastic constants (Cij) and moduli (B, G, E), respectively. The bulk modulus and the ductility increased by adding an appropriate amount of C to the M2B. The compound hardness was studied using a theoretical method based on the work of Tian. The chemical bonding of these compounds was estimated using the Mulliken population analysis and density of states, and the results indicate that the bonding behaviors of these compounds are combinations of metallic and covalent bonds.
Introduction: To investigate the effects of paroxetine (PAR) on motor and cognitive function recovery in patients with non-depressed ischemic stroke (nD-AIS).
Methods: One hundred sixty-seven patients hospitalized for non-depressed acute ischemic stroke were selected and divided into treatment (T) and control (C) groups using a random number table. All patients received conventional secondary ischemic stroke prevention and rehabilitation training; patients in Group T additionally received treatment with PAR (10 mg/day during week 1 and 20 mg/day thereafter) for 3 months. The follow-up observation lasted 6 months. The Fugl–Meyer motor scale (FMMS), Montreal cognitive assessment (MoCA), and Hamilton depression scale (HAMD) were used on D0, D15, D90, and D180 (T0, 1, 2, and 3, respectively; D180 = 90 days after treatment cessation) after study initiation, and scores were compared between the groups.
Results: The FMMS and MoCA scores differed significantly between Groups T and C at T2 and T3 (p < .05); by contrast, these scores did not differ significantly between the groups at T1 (p > .05). Furthermore, the HAMD scores differed significantly between the two groups at T3 (p < .05), but not at T1 and T2 (p > .05).
Conclusions: PAR treatment may improve motor and cognitive function recovery in patients with nD-AIS. Moreover, PAR may reduce the occurrence of depression after stroke.
The crack initiation and early growth behaviors of a TC4 titanium alloy under high cycle fatigue and very high cycle fatigue were experimentally investigated. The results show that it exhibits the duplex S–N curve characteristics associated with surface and interior failures at a stress ratio of 0.1, while it represents the similar S–N curve characteristics only related to surface failure at a stress ratio of −1. The interior failure is accompanied with the occurrence of facets, granular bright facets (GBFs), and fisheye. Slip-like patterns are observable on the facets easily formed under positive stress ratio. The interior failure process is characterized as (i) occurrence of slip lines on partial α grains under cyclic loading, (ii) initiation and growth of microcracks within some α grains, (iii) coalescence of microcracks and formation of GBF, (iv) stable long crack growth within fisheye, (v) unstable crack growth outside fisheye, and (vi) final momentary fracture.
Somatic cell nuclear transfer (SCNT) is an important technique for life science research. However, most SCNT embryos fail to develop to term due to undefined reprogramming defects. Here, we show that abnormal Xi occurs in somatic cell NT blastocysts, whereas in female blastocysts derived from cumulus cell nuclear transfer, both X chromosomes were inactive. H3K27me3 removal by Kdm6a mRNA overexpression could significantly improve preimplantation development of NT embryos, and even reached a 70.2% blastocyst rate of cleaved embryos compared with the 38.5% rate of the control. H3K27me3 levels were significantly reduced in blastomeres from cloned blastocysts after overexpression of Kdm6a. qPCR indicated that rDNA transcription increased in both NT embryos and 293T cells after overexpression of Kdm6a. Our findings demonstrate that overexpression of Kdm6a improved the development of cloned mouse embryos by reducing H3K27me3 and increasing rDNA transcription.
This study aimed to determine the effects of supplementing the diet of adult Nile tilapia Oreochromis niloticus with phosphatidylcholine (PC) on growth performance, body composition, fatty acid composition and gene expression. Genetically Improved Farmed Tilapia fish with an initial body weight of 83·1 (sd 2·9) g were divided into six groups. Each group was hand-fed a semi-purified diet containing 1·7 (control diet), 4·0, 6·5, 11·5, 21·3 or 41·0 g PC/kg diet for 68 d. Supplemental PC improved the feed efficiency rate, which was highest in the 11·5 g PC/kg diet. Weight gain and specific growth rate were unaffected. Dietary PC increased PC content in the liver and decreased crude fat content in the liver, viscera and body. SFA and MUFA increased and PUFA decreased in muscle with increasing dietary PC. Cytoplasmic phospholipase A2 and secreted phospholipase A2 mRNA expression were up-regulated in the brain and heart in PC-supplemented fish. PC reduced fatty acid synthase mRNA expression in the liver and visceral tissue but increased expression in muscle. Hormone-sensitive lipase and lipoprotein lipase expression increased in the liver with increasing dietary PC. Growth hormone mRNA expression was reduced in the brain and insulin-like growth factor-1 mRNA expression in liver reduced with PC above 6·5 g/kg. Our results demonstrate that dietary supplementation with PC improves feed efficiency and reduces liver fat in adult Nile tilapia, without increasing weight gain, representing a novel dietary approach to reduce feed requirements and improve the health of Nile tilapia.
With the improvement of the bias instability of Micro-Electromechanical Systems (MEMS) gyroscopes, the g-sensitivity error is gradually becoming one of the more important factors that affects the dynamic accuracy of a MEMS gyroscope. Hence there is a need for correcting the g-sensitivity error. However, the traditional calibration of g-sensitivity error uses a centrifuge. The calibration conditions are harsh, the process is complex and the cost is relatively high. In this paper, a fast and simple method of g-sensitivity error calibration for MEMS gyroscopes is proposed. With respect to the bias and random noise of a MEMS gyroscope, the g-sensitivity error magnitude is relatively small and it is simultaneously coupled with the Earth's rotation rate. Therefore, in order to correct the g-sensitivity error, this work models the calibration for g-sensitivity error coefficients, designs an (8+N)-position calibration scheme, and then proposes a fitting method for g-sensitivity error coefficients based on the Newton iteration and least squares methods. Multi-group calibration experiments designed on a MEMS Inertial Measurement Unit (MEMS IMU) product demonstrate that the proposed method can calibrate g-sensitivity error coefficients and correct the g-sensitivity error effectively and simply.
To better stabilize the hydrogen-terminated surface, a diamond based metal-insulator-semiconductor field-effect transistor with Zr-Si-N dielectric layer has been investigated. On the diamond epitaxial layer grown by microwave plasma chemical vapor deposition system, Pd films were patterned as the source and drain electrodes by photolithography and electron beam evaporation methods. Then, a Zr-Si-N dielectric layer and W metal film were fabricated as the gate structure by radio frequency magnetron sputtering technique. The device illustrates p-type depletion mode, in which the threshold voltage, maximum transconductance, drain current maximum, capacitance and dielectric constant were calculated to be 3.0V, 1.27mS/mm, -5.16 mA/mm, 0.275μF/cm2 and 7.8, respectively. The result suggest that Zr-Si-N dielectric layer is shown to have the ability to protect the two-dimensional hole gas.
With increasing output of petroleum coke, the value-added exploitation of petroleum coke has become a tough problem. Preparing porous carbons is a traditional way to the value-added exploitation of petroleum coke. Here, we used a facile and efficient hard-templating strategy to synthesize mesoporous carbon with high surface area from petroleum coke. N2 adsorption analyses show that the BET specific area and pore volume of the carbons can reach up to 864 m2/g and 1.37 cm3/g, respectively. To utilize the abundant mesopores of the carbons, anthraquinone-modified mesoporous carbon was tested as an electrode material for supercapacitor applications. Electrochemical measurements demonstrated that the specific capacitance reached up to 366 F/g at the current density of 1 A/g, indicating a promising prospect of using this carbon in electrochemical energy-storage field. More importantly, the strategy used in this work can be easily modified to prepare other nano-carbon materials from petroleum coke.
Petroleum coke (PC) is a low-cost and potential carbon source for electrochemical energy storage. To expand the utilization of PC in supercapacitor, PC-based activated carbons (PCACs) with heteroatoms-doped were prepared from PC by KOH chemical activation. The as-prepared carbon exhibited a high surface area (2326.4 m2/g) and hierarchical micro-mesoporous structure, resulting in a high specific capacitance (421 F/g at 1 A/g) and excellent rate performance in KOH electrolyte (217 F/g at 50 A/g). Meanwhile, to improve the high-rate capacitive performance of PCACs in H2SO4 electrolyte, functionalized activated carbon (HQ/PCAC-4) was prepared by physically adsorbing the hydroquinone (HQ) on PCACs. The HQ/PCAC-4 showed an unprecedented capacitance value of 300.2 F/g even at an ultrahigh current density of 50 A/g. In addition, the energy density of HQ/PCAC-4 in H2SO4 electrolyte reached 19.5 W h/kg. The high energy density and excellent rate performance ensured their prosperous application in high-power energy storage system.
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.
The metamorphic responses of mussel (Mytilus coruscus) larvae to pharmacological agents affecting G proteins and the adenylate cyclase/cyclic AMP (AC/cAMP) pathway were examined in the laboratory. The G protein activators guanosine 5′-[β,γ-imido]triphosphate trisodium salt hydrate and guanosine 5′-[γ-thio]triphosphate tetralithium salt only induced larval metamorphosis in continuous exposure assays, and the G protein inhibitor guanosine 5′-[β-thio]diphosphate trilithium salt did not exhibit inducing activity. The non-specific phosphodiesterase inhibitor theophylline and the cAMP-specific phosphodiesterase IV inhibitor 4-(3-Butoxy-4-methoxybenzyl)imidazolidin-2-one exhibited inducing activity, while the non-specific phosphodiesterase inhibitor 3-Isobutyl-1-methylxanthine only showed inducing activity at 10−4 M in continuous exposure assays. The cyclic nucleotide analogue N6,2′-O-Dibutyryladenosine 3′,5′-cyclic monophosphate sodium salt did not exhibit significant inducing activity. Both the adenylate cyclase activator forskolin and the adenylate cyclase inhibitor nitroimidazole exhibited inducing activity at 10−4 to 10−3 M concentrations in continuous exposure assays. Among these tested agents, the adenylate cyclase inhibitor (±)-miconazole nitrate salt showed the most promising inducing effect. The present results indicate that G protein-coupled receptors and signal transduction by AC/cAMP pathway could mediate metamorphosis of larvae in this species.
In this paper, the recent studies of laboratory astrophysics with strong magnetic fields in China have been reviewed. On the Shenguang-II laser facility of the National Laboratory on High-Power Lasers and Physics, a laser-driven strong magnetic field up to 200 T has been achieved. The experiment was performed to model the interaction of solar wind with dayside magnetosphere. Also the low beta plasma magnetic reconnection (MR) has been studied. Theoretically, the model has been developed to deal with the atomic structures and processes in strong magnetic field. Also the study of shock wave generation in the magnetized counter-streaming plasmas is introduced.
This article addresses the resolution of the inverse problem for the parameter identification in orthotropic materials with a number of measurements merely on the boundaries. The inverse problem is formulated as an optimization problem of a residual functional which evaluates the differences between the experimental and predicted displacements. The singular boundary method, an integration-free, mathematically simple and boundary-only meshless method, is employed to numerically determine the predicted displacements. The residual functional is minimized by the Levenberg-Marquardt method. Three numerical examples are carried out to illustrate the robustness, efficiency, and accuracy of the proposed scheme. In addition, different levels of noise are added into the boundary conditions to verify the stability of the present methodology.
Cognition and sleep deficits occur in amnestic mild cognitive impairment (aMCI) and vascular cognitive impairment-no dementia (VCIND). However, how memory and sleep deficits differ between aMCI and VCIND remains unclear.
Fifty aMCI and 50 VCIND patients and 38 sex- and age-matched healthy controls (HCs) were administered the Hopkins Verbal Learning Test-Revised (HVLT-R), Trail Making Test-A/B (TMT-A/B), Wisconsin Card Sorting Test (WCST), Paced Auditory Serial Addition Test (PASAT), Symbol Digit Modalities Test (SDMT), Benton Judgment of Line Orientation (JLO) test, Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), and Insomnia Severity Index (ISI) to quantify cognitive deficits and subjective sleep disturbance.
Compared with VCIND patients, aMCI patients had lower HVLT-R scores for total recall (p < 0.001), delayed recall (p < 0.001) and recognition (p = 0.001), and for total-recall (p = 0.002) and delayed-recall (p < 0.001) semantic clustering ratios (SCRs). However, VCIND patients exhibited more obvious executive dysfunction (TMT-A, p < 0.001; TMT-B, p < 0.001; WCST, p < 0.001), lower information processing speed (PASAT, p = 0.003; SDMT, p < 0.001), and more severe sleep disturbance (PSQI, p < 0.001; ESS, p < 0.001; ISI, p < 0.001). Additionally, sleep quality and efficiency were related to total and delayed recall (all r values from −0.31 to −0.60, p < 0.05) in aMCI and VCIND.
aMCI and VCIND differ in cognitive function, memory strategy and sleep impairment; these characteristics are helpful to identify and distinguish patients with very early cognitive impairment. Our results also suggest that memory deficits are associated with sleep disturbance in aMCI and VCIND.
For understanding the dissipation in a rotating flow when resonance occurs, we study the rotating flow driven by the harmonic force in a periodic box. Both the linear and nonlinear regimes are studied. The various parameters such as the force amplitude
, the force frequency
, the force wavenumber
and the Ekman number
are investigated. In the linear regime, the dissipation at the resonant frequency scales as
, and it is much stronger than the dissipation at the non-resonant frequencies on large scales and at low Ekman numbers. In the nonlinear regime, at the resonant frequency the effective dissipation (dissipation normalised with the square of the force amplitude) is lower than in the linear regime and it decreases with increasing force amplitude. This nonlinear suppression effect is significant near the resonant frequency but negligible far away from the resonant frequency. Opposite to the linear regime, in the nonlinear regime at the resonant frequency the lower Ekman number leads to lower dissipation because of the stronger nonlinear effect. This work implies that the previous linear calculations overestimated the tidal dissipation, which is important for understanding the tides in stars and giant planets.