Effect of hexagonal structure nanoparticles on the morphological performance of the ceramic scaffold using analytical oscillation response

Porous bony scaffolds are utilized to manage the growth and migration of cells from adjacent tissues to a defective position. In the current investigation, the effect of titanium oxide (TiO₂) nanoparticles on mechanical and physical properties of porous bony implants made of polymeric polycaprolactone (PCL) is studied. The bio-nanocomposite scaffolds are prepared with composition of nanocrystalline hydroxyapatite (HA) and TiO₂ powder using the freeze-drying technique for different weight fractions of TiO₂ (0 wt%, 5 wt%, 10 wt%, and 15 wt%). In order to identify the microstructure and morphology of the fabricated porous bio-nanocomposites, the X-ray diffraction (XRD), atomic force microscope (AFM) and scanning electron microscopy (SEM) are employed. Also, the biocompatibility and biodegradability of the manufactured scaffolds are examined by placing them in a simulated body fluid (SBF) for 21 days, their weight and pH changes are measured. The rate of degradation of the PCL-HA scaffold can be controlled by varying the percentage of its constituent components. Due to an increasing growth and activity of bone cells and the apatite formation on the free surface of the fabricated bio-nanocomposite implants as well as their reasonable mechanical properties, they have the potential to be used as a bone substitute. Additionally, with the aid of the experimentally extracted mechanical properties of the scaffolds, the vibrational characteristics of a beam-type implant made of the proposed porous bio-nanocomposites are explored. The results obtained from SEM image indicate that the scaffolds produced by the employed method have high total porosity (70%–85%) and effective porosity. The pore size is obtained between 60 and 200 μm, which is desirable for the growth and propagation of bone cells. Also, it is revealed that the addition of TiO₂ nanoparticles leads to reduce the rate of dissolution of the fabricated bio-nanocomposite scaffolds.     

Distributed ledger technology in supply chains: a transaction cost perspective

With the emergence of distributed ledger technology (DLT), numerous practitioners and researchers have proclaimed its beneficial impact on supply chain transactions in the future. However, the vast majority of DLT initiatives are discontinued after a short period. With the full potential of DLT laying far down the road, especially managers in supply chain management (SCM) seek for short-term cost-saving effects of DLT in order to achieve long-term benefits of DLT in the future. However, the extant research has bypassed grounding long-term as well as short-term effects of DLT on supply chain transaction with empirical data. We address this shortcoming, following an abductive research approach and combining empirical data from a multiple case study design with the corresponding literature. Our study reveals that the effects of DLT on supply chain transactions are two-sided. We found six effects of DLT solutions that have a cost-reducing or cost avoidance impact on supply chain transactions. In addition, we found two effects that change the power distribution between buyers and suppliers in transactions and a single effect that reduces the dependency of supply chain transactions on third parties. While cost-reducing and avoidance as well as dependency-reducing effects are positive effects, the change in power distribution might come with disadvantages. With these findings, the paper provides the first empirical evidence of the impact of DLT on supply chain transactions, which will enable managers to improve their assessment of DLT usage in supply chains.     

Characterization of boron nitride nanosheets synthesized by boron-ammonia reaction

Boron nitride nanosheets (BNNS) with thickness 5–11 nm were successfully produced when pure boron powder (1–2 μm) interacted with ammonia gas in chemical vapour deposition set up. Under the optimized parameters, at 1200 °C and for uninterrupted 1 h of reaction duration, 2D BNNS with thickness of ca.11 nm were synthesized. BNNS were characterized by X-ray diffraction (XRD) for crystal structure, scanning electron microscopy for dimensions and morphology, energy dispersive X-ray analysis for chemical composition and Fourier transform infrared spectroscopy for sp² BN bond detection. The thickness of BNNS determined from both XRD data (using Scherrer equation) and atomic force microscopic analysis confirmed the stated product thickness. The BNNS obtained at 1200 °C had high crystallinity, purity and yield.     

FEM analysis of the vibrational motion of oblique piezoelectric microcantilever in the vicinity of a sample surface in liquid

This article examines an oblique Microcantilever (MC) with an extended piezoelectric layer in liquid. The study of hydrodynamic force in MC which has been floated in viscous fluid is considered as paramount importance. To model the Vibrational motion, the Hamilton's principle has been used. For this purpose, the Vibrational motion equation has been modeled by considering the continuous beam based on the Euler–Bernoulli beam theory in liquid. Furthermore, using the Galerkin method and the Newmark algorithm, the differential equations of the MC has been solved. In this modeling, the inter-atomic forces between the MC tip and the sample surface have been considered in addition to the hydrodynamic and squeeze forces. The simulation results illustrate a reduction in the sensitivity of the vibrational motion under the effect of the squeeze force during the angularization of the MC. Moreover, the results illustrate that by reducing the MC distance from the sample surface, the Vibration amplitude decreases due to the increase in the fluid squeeze force. At the end, it has been shown that the time delay in sample surface topography in liquid substantially decreases in comparison with the air.     

Improved direct inverse tracking control of a piezoelectric tube scanner for high-speed AFM imaging

For a piezoelectric tube scanner (PTS), this paper proposes an improved direct inverse tracking control algorithm and apply it to an atomic force microscope (AFM) to accomplish high-speed scanning tasks. That is, to enhance the high-speed tracking control performance of a PTS, an improved direct inverse rate-dependent Prandtl–Ishlinskii (P–I) model is firstly constructed, which includes a polynomial module to eliminate the structure nonlinearity. Based on the model, a practical feedforward control law is then designed to implement high-speed tracking control for a high-frequency trajectory with strong robustness, which presents the advantages of high-speed response, simple structure and convenient implementation. Subsequently, the designed feedforward law is combined with a feedback component, and the combined control strategy is employed in an AFM to accomplish fast imaging tasks. Numerous experimental results are then collected, which convincingly demonstrate the superior performance of the proposed practical model/control scheme.     

A study on the thermoelectric properties of ALD-grown aluminum-doped tin oxide with respect to nanostructure modulations

The thermoelectric properties of aluminum-doped tin oxide (ATO) thin films synthesized by thermal atomic layer deposition (ALD) were studied with respect to the aluminum concentration. The overall aluminum content in each layer was modulated by adjusting the relative number of tin oxide (SnO₂) and aluminum oxide (Al₂O₃) growth cycles, where a sequential process involving n cycles of SnO₂ growth followed by 1 cycle of Al₂O₃ deposition was performed (building up a super-cycle). The electrical conductivity (620 S/cm), free carrier concentration (1.23x10²¹ cm^-3), and power factor (0.49 mW/K²m) increase until their maximum values are reached when the Al content is approximately 1.50 at% of the cations, and decrease as more Al is added in. On the other hand, the Seebeck coefficient decreases monotonically as the Al content increases up to about 2.88 at%, and begins to increase with further Al doping. Here the thermoelectric efficiency is therefore determined primarily by the free carrier concentration, while the Seebeck coefficient appears to be influenced by the overall crystal structure.     

Enhanced thermal stability of Bi2Te3-based alloys via interface engineering with atomic layer deposition

The ease of Te sublimation from Bi₂Te₃-based alloys significantly deteriorates thermoelectric and mechanical properties via the formation of voids. We propose a novel strategy based on atomic layer deposition (ALD) to improve the thermal stability of Bi₂Te₃-based alloys via the encapsulation of grains with a ZnO layer. Only a few cycles of ZnO ALD over the Bi₂Te_2.7Se_0.3 powders resulted in significant suppression of the generation of pores in Bi₂Te_2.7Se_0.3 extrudates and increased the density even after post-annealing at 500 °C. This is attributed to the suppression of Te sublimation from the extrudates. The ALD coating also enhanced grain refinement in Bi₂Te_2.7Se_0.3 extrudates. Consequently, their mechanical properties were significantly improved by the encapsulation approach. Furthermore, the ALD approach yields a substantial improvement in the figure-of-merit after the post-annealing. Therefore, we believe the proposed approach using ALD will be useful for enhancing the mechanical properties of Bi₂Te₃-based alloys without sacrificing thermoelectric performance.     

我国建筑石料用灰岩采矿权成交价变化分析

砂石资源采矿权出让收益是地方财政收入的重要来源。近年来,砂石资源供应紧张价格大幅上涨的背景下,本文以典型的砂石资源建筑石料用灰岩为例,分析了全国及部分典型省份建筑石料用灰岩采矿权成交价的变化特征,主要结论是2011～2018年我国建筑石料用灰岩采矿权平均成交单价与砂石市场供应价格均呈上升趋势但前者涨幅远高于后者,并且采矿权成交单价的区间分布结构年度变化差异也较大,不同区域平均成交单价年度变化规律分异明显,贵州、甘肃两省采矿权成交单价相对较低且变化幅度相对较小,山西、吉林、湖北、广西4省采矿权成交单价相对较高且变化幅度相对较大。最后,从平抑砂石价格过快上涨、加强矿业权市场建设、促进砂石资源区域供需平衡、维护良好砂石市场价格秩序的角度提出了有关政策建议。     

原子荧光紧密内插法快速测定莲藕中砷的生物吸收比

目的 为建立一种快速测定莲藕中微量砷和生物吸收比的新型原子荧光法。方法 用微波辅助消解样品,用紧密内插法测定莲藕各组织和土壤中的砷。结果 结果表明：藕肉和藕节中砷的质量分数较小,藕皮和藕尖中砷的质量分数较大。各组织砷的生物吸收比为79.54%-22.03%,与国标法相比,通过显著性检验,方法之间没有显著性差异,结论的置信度为95%。结论 该法不需要绘制标准曲线和测定空白,快速简便,计算简单,具有一定的创新性和推广应用价值。