Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a ...number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.
The migration process of magnetic nanoparticles and colloids in solution under the influence of magnetic field gradients, which is also known as magnetophoresis, is an essential step in the ...separation technology used in various biomedical and engineering applications. Many works have demonstrated that in specific situations, separation can be performed easily with the weak magnetic field gradients created by permanent magnets, a process known as low-gradient magnetic separation (LGMS). Due to the level of complexity involved, it is not possible to understand the observed kinetics of LGMS within the classical view of magnetophoresis. Our experimental and theoretical investigations in the last years unravelled the existence of two novel physical effects that speed up the magnetophoresis kinetics and explain the observed feasibility of LGMS. Those two effects are (i) cooperative magnetophoresis (due to the cooperative motion of strongly interacting particles) and (ii) magnetophoresis-induced convection (fluid dynamics instability originating from inhomogeneous magnetic gradients). In this feature article, we present a unified view of magnetophoresis based on the extensive research done on these effects. We present the physical basis of each effect and also propose a classification of magnetophoresis into four distinct regimes. This classification is based on the range of values of two dimensionless quantities, namely, aggregation parameter N* and magnetic Grashof number Gr m, which include all of the dependency of LGMS on various physical parameters (such as particle properties, thermodynamic parameters, fluid properties, and magnetic field properties). This analysis provides a holistic view of the classification of transport mechanisms in LGMS, which could be particularly useful in the design of magnetic separators for engineering applications.
Tulisan ini menjelaskan tentang kepentingan China di Timur Tengah, khususnya terhadap Arab Saudi dan Iran. Tujuan artikel ini untuk memahami lebih dalam kepentingan apa yang melatarbelakangi China ...yang menjadikan dirinya sebagai mediator dalam rekonsiliasi hubungan antara Arab Saudi - Iran. Metode yang digunakan dalam penelitian ini adalah deskriptif analitis, yaitu mendeskripsikan terlebih dahulu materi pembahasan dan kemudian dianalisis. Adapun teori yang digunakan adalah kepentingan nasional, yang terdiri dari kepentingan pertahanan, kepentingan ekonomi, kepentingan tatanan dunia, dan kepentingan ideologi. Penelitian ini menghasilkan kesimpulan bahwa pada kepentingan pertahanan, China memiliki kepentingan untuk memperkuat aliansi militer sekaligus penjualan senjata kepada Saudi-Iran. Pada kepentingan ekonomi, Saudi-Iran merupakan sumber utama penghasil minyak, gas dan energi serta lahan strategis untuk investasi bagi China. Dalam kepentingan tatanan dunia, menjalin kerja sama dengan Saudi-Iran tentu membuat eksistensi China di dunia internasional semakin besar. Terakhir, China membutuhkan dukungan Saudi-Iran dalam memerangi Uyghur yang merupakan kelompok Islam.
•Engineered alkali-activated cementitious composites (EACC) was developed using 100% palm oil fuel ash (POFA).•Different sulfate solutions effect on POFA-EACC compressive strength was ...studied.•POFA-EACC has better durability performance with MgSO4(aq) solution than Na2SO4(q) solution.
This paper presents an investigation into the durability performance of Palm Oil Fuel Ash-based Engineered Alkaline-activated Cementitious Composite (POFA-EACC) mortar exposed to sulfate environment. Cube specimens measuring 50mm×50mm×50mm were prepared from POFA-EACC and exposed to the sulfate solutions after one day of heat curing. The POFA-EACC mixtures were prepared with 100% POFA, 2% volume fraction of polyvinyl alcohol (PVA) fibres, alkali-activator (Na2SiO3(aq)/NaOH(aq)) ratios of 2.5 and different molarities (10, 12 and 14M) of NaOH(aq). Three salt solutions (5% Na2SO4(aq), 5% MgSO4(aq) and 2.5% Na2SO4(aq)+2.5% MgSO4(aq)) were used to study the resistance of the POFA-EACC mortar specimens to sulfate for 9months. Parameter used for the study are changes in weight, compressive strength and visual changes. SEM and XRD were employed to characterize and study changes in the microstructure of the exposed specimens. The results obtained from this study revealed that the specimens exposed to 5% MgSO4(aq) solution have better durability performance than the specimens exposed to 5% Na2SO4(aq).
This study describes the government's strategy in Indonesia under the leadership of Joko Widodo to strengthen the Natuna border area. The Natuna area is a point of discussion as there are often ...territorial conflicts. This study aims to answer the question about the government's strategy to strengthen the border zone in Natuna. This study uses library research methodology and the Revolution in Military Affairs (RMA) concept to analyze the process. After conducting research, it can be concluded that to reinforce the border area at Natuna, the government is making efforts to improve the military posture by constructing several new military units. Then the government is also looking at diplomatic means in the ASEAN region to resolve the territorial dispute with China in the South China Sea. This is because there is no mutual agreement, considering that Indonesia is based on the 1982 UNCLOS, while China has a view of the Nine-Dash Line.
This research investigated the effects of alumina (Al2O3) micro- and nano-particles on poly(methyl methacrylate) (PMMA) denture base. Al2O3 was surface treated using ...(3-methacryloxypropyl)trimethoxysilane (?-MPS), added to methyl methacrylate (MMA), and mixed with PMMA powder. The filler volume fractions in the micro-composites were 0.5, 1, 2, 5 and 7 wt. %, whereas those in the nano-composites were 0.13, 0.25, 0.5, 1, 2 and 5 wt. %. The treated fillers were examined using Fourier transform infrared spectroscopy (FTIR). The influence of filler size and loading on mechanical properties was studied using fracture toughness and flexural tests. The thermal stability of the PMMA/Al2O3 composites was investigated using thermogravimetric analysis (TGA). In addition, the water absorption and solubility characteristic of the prepared composites was also investigated. The FTIR spectra showed new absorption bands, indicating the occurrence of surface modifications. Both micro- and nanoscale particles showed increased fracture toughness. The maximum value of 2.02 MPa?m1/2 was achieved with the addition of 0.5 wt. % nano-Al2O3, which accounts for a 39 % increase. In contrast to the flexural strength, the flexural modulus improved with increasing filler content. The micro-composites showed higher thermal stability than nano-composites. The water absorption and solubility of the prepared composites were slightly higher than those of the control. The use of low concentrations of Al2O3 nanoparticles may be of considerable interest in future studies to improve the mechanical properties of PMMA denture base.
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Zirconia toughened alumina (ZTA) is a promising advanced ceramic material for a wide range of applications that are subjected to dynamic loading. Therefore, the investigation of dynamic compressive ...strength, fracture toughness and hardness is essential for ZTA ceramics. However, the relationship between these mechanical properties in ZTA has not yet been established. An example of this relationship is demonstrated using ZTA samples added with MgO prepared through conventional sintering. The microstructure and mechanical properties of ZTA composites were characterized. The hardness of ZTA composites increased for ≤0.7 wt.% MgO due to the pinning effect of MgO and decrease of the porosity in the microstructure. Oppositely, the fracture toughness of ZTA composites continuously decreased due to the size reduction of Al
O
grains. This is the main reason of deteriorate of dynamic compressive strength more than 0.2 wt.% of MgO addition. Therefore, the SHPB test shows the improvement of the dynamic compressive strength only up to a tiny amount (0.2 wt.% of MgO addition) into ZTA ceramics.
To date, the compatibility of two different materials of composites has been determined solely by the empirical surface wettability approach, using methods such as contact angle measurement. However, ...this method can be quite cumbersome, requiring specific equipment and different liquid probes. Therefore, this paper aims to develop a simplified approach to determining surface wettability, incorporating novel generalized expressions that account for the interfacial interaction compatibility of various constituents within composites. First, an economical, simplistic, and verified water probe method is employed to measure apparent contact angles. The determined apparent contact angles are shown to fit well within the thresholds established from the available findings. Then, new mathematical expressions incorporating the adhesion concept are derived to describe the constitutive relationship between the ratios of apparent contact angles of two materials for composites formation and their liquid-solid interfacial tension by fitting data gathered from existing studies. The newly developed constitutive equations offer a convenient and reliable means to determine the compatibility relationships of numerous composite constituent mixes for varying contact angle ratios. This approach enables a simple and cost-effective estimation of surface interaction via the apparent contact angle between water and the composite constituents.
Convective current driven by momentum transfer between magnetic nanoparticles (MNPs) and their surrounding fluid during magnetophoresis process under a low gradient magnetic field (<100 T m(-1)) is ...presented. This magnetophoresis induced convective flow, which imposed direct hydrodynamic effects onto the separation kinetics of the MNPs under low gradient magnetic separation (LGMS), is analogous to the natural convection found in heat transportation. Herein, we show the significance of the induced convection in controlling the transport behavior of MNPs, even at a very low particle concentration of 5 mg L(-1), and this feature can be characterized by the newly defined magnetic Grashof number. By incorporating fluid flow equations into the existing magnetophoresis model, we reveal two unique features of this convective flow associated with low gradient magnetophoresis, namely, (1) the continuous homogenization of the MNPs solution and (2) accompanying sweeping flow that accelerates the collection of MNPs. According to both simulation and experimental data, the induced convection boosts the magnetophoretic capture of MNPs by approximately 30 times compared to the situation with no convection.
An overview of studies on mechanistic model-based control of biodiesel production process is presented and discussed, focusing on control strategies including, among others, plantwide control, model ...predictive control, and optimal control. The paper highlights past studies that used advanced control strategies to improve the economic performance of biodiesel production. Based on the outcome of the literature review, there are limited applications of advanced control strategies in the biodiesel production process, especially within the plantwide control (PWC) framework. Only a few studies addressed the optimization and control of the biodiesel process beyond the transesterification reactor. Decentralized plantwide control architecture using a heuristic-based method with simulations in Aspen Plus Dynamic is currently employed to demonstrate how to facilitate and enhance the process performance of biofuel production. The review shows a need for a simple, effective, and easily implementable plantwide design control capable of achieving optimal profitability, controllability, and safety.
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