Synthesis methods and powder quality of titanium monocarbide

Titanium monocarbide(TiC),which is the most stable titanium-based carbide,has attracted considerable interest in the fields of energy,catalysis,and structural materials due to its excellent properties.Synthesis of high-quality TiC powders with low cost and high efficiency is crucial for industrial applications;however major challenges face its realization.Herein,the methods for synthesizing TiC powders based on a reaction system are reviewed.This analysis is focused on the underlying mechanisms by which synthesis methods affect the quality of powders.Notably,strategies for improving the synthesis of highquality powders are analyzed from the perspective of enhancing heat and mass transfer processes.Furthermore,the critical issues,challenges,and development trends of the synthesis technology and application of high-quality TiC powder are discussed.

Synthesis methods of functionalized nanoparticles:a review

With the recent advancement in nanotechnology,nanoparticles(NPs)offer an ample variety of smart functions than conventional materials in various aspects.As compared to larger particles,NPs possess unique characteristics and excellent abilities,such as low toxicity,chemical stability,surface functionality,and biocompatibility.These advantageous properties allow them to be widely utilized in many applications,including biomedical applications,energy applications,IT applications,and industrial applications.In order to fulfill the increasing demands of NP applications,existing NP synthesis methods need to be improved based on the requirements of different applications to further their usage.A comprehensive understanding of the relationships between synthesis parameters and properties of NPs can help us better fine-tune them with designed properties and minimal toxicity.This review paper will discuss the commonly used synthesis methods of functionalized NPs,as well as future directions and challenges to develop various synthesis methods further.

Structures and Properties of PEDOT Nanotubes Prepared by a Template Synthesis Method

PEDOT nanotubes were prepared by a template synthesis method. Based on our template, it was deduced that there are two successive processes in the formation of nanotubes. The first step is soakage of the porous templates by a polymer solution, and the second step is adsorption of free charged cationic groups and doped PEDOT onto the template surface with negative charges. XRD results showed that well orientated PEDOT chains were formed during the synthesis, moreover the arrange conductivity of molecular chains strongly affect the structures of PEDOT nanotubes. The nanotubes were measured to be about 5.5-17.6 S/cm, which is higher than that of nanotube pellet due to the high contact resistance between the adjacent nanotubes.

Comparative study on multibody vehicle dynamics models based on subsystem synthesis method using Cartesian and joint coordinates

The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and each subsystem can be solved separately. In the subsystem synthesis method, various coordinate systems can be used and various integration methods can be applied in each subsystem, as long as the effective mass matrix and the effective force vector are properly produced. In this paper, comparative study has been carried out for the subsystem synthesis method with Cartesian coordinates and with joint relative coordinates. Two different integration methods such as an explicit integrator and an explicit implicit integrator are employed. In order to see the accuracy and computational efficiency from the different models based on the different coordinate systems and different integration methods, a rough terrain run simulations has been carried out with a 6 × 6 off-road multibody vehicle model.

LaMnO_(3)(La_(0.8)Sr_(0.2)MnO_(3))Perovskites for Lean Methane Combustion:Effect of Synthesis Method

The effect of the preparation method on the properties of LaMnO3 and La0.8Sr0.2MnO3 perovskite was studied. Materials were prepared by four methods: sol-gel, chemical combustion, solvothermal and spray pyrolysis and characterized. The effect of the synthesis method on the texture, acid-base character of the surface, reducibility with hydrogen, oxygen desorption, surface composition and catalytic activity for combustion of lean methane was studied. It was found that synthesis method affects physicochemical properties of obtained materials-solvothermally produced materials exhibit well-developed surface area, presence of reactive oxygen species on surface and high catalytic activity for CH4 combustion. Generally, LaMnO3 and La0.8Sr0.2MnO3 perovskites show catalytic activity for lean CH4 combustion comparable or higher than the activity of 0.5 wt.% Pt/Al2O3 but lower than 1 wt.% Pd/Al2O3.

Mechanistic investigation on Hg^(0) capture over MnO_(x) adsorbents:effects of the synthesis methods

This study demonstrated the impacts of the synthesis methods on the textural structures,chemical properties,and Hg^(0)capture capability of the MnO_(x)system.Compared with the samples synthesized using the precipitation(PR)and hydrothermal(HT)methods,the adsorbent prepared via the sol-gel(SG)technique gave the best performance.At 150℃,ca.90%Hg^(0)removal efficiency was reached after 7.5 h for MnO_(x)prepared by the SG method,ca.40%higher than that of the other two methods.The specific surface area of the adsorbent synthesized via the SG technique(23 m^(2)/g)was almost double that of the adsorbent prepared by the HT method(12 m^(2)/g)and three times that of the one prepared by the PR method(7 m^(2)/g).The presence of plentiful acid sites from the SG method facilitated the physisorption of Hg^(0),making more Hg^(0)available to be oxidized to HgO by the redox sites and thus giving the adsorbent prepared by the SG method the highest Hg^(0)removal efficiency.The strong oxidative ability accelerated the oxidation of the physically adsorbed Hg^(0)to HgO,which explained the higher Hg^(0)removal efficiency of the sample prepared using the HT method than that of the one synthesized by the PR technique.During the whole Hg^(0)removal cycles,chemisorption dominated,with the initial adsorption stage and the external mass-transfer process playing important roles.

Fabrication plate-like BaBi_(4)Ti_(4)O_(15) single-crystalline particles by the molten salt synthesis method

Plate-like single-crystalline BaBi_(4)Ti_(4)O_(15) particles were synthesized by the molten salt synthesis(MSS)method.The effects of sintering temperature,holding time,and NaCl-KCl molten salt content on the phase structure and morphology of plate-like BaBi_(4)-Ti_(4)O_(15) particles were investigated.The results show that plate-like BaBi_(4)Ti_(4)O_(15) particles can be synthesized when the sintering temperature is above 800°C.The size of particles increases with increasing sintering temperature and molten salt content.Largely anisotropic plate-like BaBi_(4)Ti_(4)O_(15) particles with diameter≥10μm and thickness of~0.3μm can be obtained under the optimum process parameters.The crystal structure of BaBi_(4)Ti_(4)O_(15) was determined as A21am by TEM,which should be attributed to the Bi3+and Ba2+diffusing into[TiO6]octahedrons.

Sparse antenna array design methodologies:A review

Designing a sparse array with reduced transmit/receive modules(TRMs)is vital for some applications where the antenna system’s size,weight,allowed operating space,and cost are limited.Sparse arrays exhibit distinct architectures,roughly classified into three categories:Thinned arrays,nonuniformly spaced arrays,and clustered arrays.While numerous advanced synthesis methods have been presented for the three types of sparse arrays in recent years,a comprehensive review of the latest development in sparse array synthesis is lacking.This work aims to fill this gap by thoroughly summarizing these techniques.The study includes synthesis examples to facilitate a comparative analysis of different techniques in terms of both accuracy and efficiency.Thus,this review is intended to assist researchers and engineers in related fields,offering a clear understanding of the development and distinctions among sparse array synthesis techniques.

Effect of synthesis methods on activity of V2O5/CeO2/WO3-TiO2 catalyst for selective catalytic reduction of NOx with NH3

The effect of synthesis methods on the activity of V/Ce/WTi catalysts was investigated for the selective catalytic reduction（SCR） of NO_x by NH_3. V/Ce/WTi-DP（deposition precipitation） catalyst showed excellent NH_3-SCR performance, especially the better medium-temperature activity and the less N_2O formation than V/Ce/WTi-IMP（impregnation）. These catalysts were characterized by X-ray diffraction（XRD）, Brumauer-Emmett-Teller（BET）, X-ray photoelectron spectroscopy（XPS）, temperature-programmed reduction（H_2-TPR）, and in situ DRIFTS techniques. The XPS and H_2-TPR results revealed that V/Ce/WTi-DP exhibited more surface Ce species, higher level of Oα and higher reducibility of Ce species. Reflected by in situ DRIFTS results, the deposition precipitation method（DP） contributed to a greater amount of weakly adsorbed NO_2, monodentate nitrate and NH_3 species with better reactive activity. Meanwhile, the cis-N_2O_2^（2-） species, an intermediate for N_2O formation, was very limited. As a result, these advantages brought about the superior SCR activity and N_2 selectivity for V/Ce/WTi-DP.

Study on Component Synthesis Active Vibration Suppression Method Using Zero-placement Technique

The component synthesis active vibration suppression method （CSVS） can be applied to suppress the vibration of flexible systems. By this method, several same or similar time-varying components are arranged according to certain rules along the time axis. The synthesized command can suppress the arbitrary unwanted vibration harmonic while achieving the desired rigid body motion. The number of the components increases rapidly when the number of harmonic vibration is growing. In this article, the CSVS based on zero-placement technique is used to construct the synthesized command to suppress the multi-harmonics simultaneously in the discrete domain. The nature of zero-placement method is to put enough zeros to cancel system poles at necessary points. The designed synthesized command has equal time intervals between each component and which is much easier to be implemented. Using this method, the number of components increases linearly with the increasing of the number of being suppressed harmonics. For the spacecraft with flexible appendages, CSVS based on zero-placement is used to design the time optimal large angle maneuver control strategy. Simulations have verified the validity and superiority of the proposed approach.

Kinematic synthesis method for the one-degree-of-freedom jumping leg mechanism of a locust-inspired robot

The one-degree-of-freedom(DOF) mechanism has a simple structure, convenient control, and high stiffness, and it has been applied in many micro jumping robots. Meanwhile, the six-and eight-bar mechanisms can satisfy more complex motion requirements than the four-bar jumping leg mechanism and they have good application prospects. However, the lack of effective design methods limits the application range of these mechanisms. In this work, a type and dimensional integration synthesis method was proposed with the one-DOF six-bar leg mechanism as the research object. The initial tibia and femur were determined based on the kinematic chain atlas, and configuration design was implemented through the superposition of links.When a closed chain was formed in the superposition process, the feasible range of the link length was analyzed by considering the constraint conditions. The proposed method innovatively establishes the relationship between the kinematic chain atlas and the configuration, and the feasible length ranges of the links can be quickly obtained simultaneously. Several examples were provided to prove the feasibility of the kinematic synthesis method. This method provides a useful reference for the design of one-DOF mechanisms.

A new speech synthesis method based on the LMA vocal tract model

A new speech synthesis algorithm based on the LMA filter in Chinese text-to-speech systern is introduced. Using this method, the system can not only generate speech with higher quality, but also have a more powerful ability to modify the prosodic parameters, which ensures a far more natural and intelligible synthesized speech than ever before. First, the fundamental principles of the LMA filter and the construction of the synthesizer are presented, then, how to modify the acoustic parameters with this synthesizer is described; finally, the quantitative evaluation of the system's performance is shown while compared with a relatively successful PSOLA synthesizer KDTALK_1

A synthesis method based on speech production and articulatory model

A method to synthesize formant targeted sounds based on speech production model and Reflection-Type Line Analog (RTLA) articulatory synthesis model is presented. The synthesis model is implemented with scattering process derived from a RTLA of vocal tract system according to the acoustic mechanism of speech production. The vocal-tract area function which controls the synthesis model is derived from the first three formant trajectories by using the inverse solution of speech production. The proposed method not only gives good naturalness and dynamic smoothness, but also is capable to control or modify speech timbres easily and flexibly. Further and mores it needs less number of control parameters and very low update rate of the parameters.

A METHOD OF SYNTHESIS OF PHENYL-LACTIC ACID AND SUBSTITUTED PHENYL LACTIC ACIDS

A method for the conversion of α-acetamido-β-substituted phenyl acrylic acid (αtβSPAA)into substituted phenyl lactic acid(SPLA)is described and an improved Clemmensen reduction reagent is used.

NEW METHOD OF SYNTHESIS OF 1-OXO-3-ACETONYL-DIHYDROBENZO(C)FURAN

o-Carboxybenzaldehyde (1)and acetone gave the Claisen-Schmidt condensation product, which readily cyclizes on acidification to give 1-oxo-3-acetonyl-dihydrobenzo [c]furan(4)in 68% yield. Other methyl ketones behaved similarly.

A LOW-PRESSURE AND ONE-STEP METHOD FOR THE SYNTHESIS OF ALKYLIDYNETRICOBALT NONACARBONYL CLUSTERS:RCCo_8(CO)_9

Metal clusters RCCo_3(CO)_9(R-H,C1,Br,CH_3,Ph) were prepared in 18.8-57.3% yields from the reaction of cobalt(Ⅱ)salt and RCX_a under mild PTC conditions(latm CO,25℃).The cobalt salt was reduced to Co(CO)_4 in the presence of Na_3S_2O_4.

A NEW CONVENIENT METHOD FOR THE SYNTHESIS OF PERFLUOROALKYL 2H-PYRROLE

The reaction between 2,5-Dimethylpyrrole (1) and R_FI (2)(R_F: a, Cl(CF_2)_4; b, Cl(CF_2)_6; c, Cl(CF_2)_8; d, n-C_6F_(13); e, n-C_8F_(17)) in the presence of Na_2S_2O_4-NaHCO_3 in acetonitrile resulted in the formation of 2-perfluoroalkyl-2,5-dimethyl-2H-pyrrole (3) as a major product in good yield.

A NEW METHOD FOR THE SYNTHESIS OF METHACRYLIC ACID FROM ISOBUTYRALDEHYDE

Isobutyraldehyde was used as starting material via three steps: oxidation, chlorination and dehydro-chlorination to yield methacrylic acid. The total yield of methacrylic acid is 49.7%.

Synthesis of Ordered Ultra-long Manganite Nanowires via Electrospinning Method

We develop a new electrospinning method to prepare ultra-long ordered La1-xSrxMnO3 （LSMO） nanowires. The length is up to several centimeters and is only limited by the size of the collector. The well-ordered straight-line structure ensures the transport measurement, which is impossible to be carried out for the random nanowires fabricated by the traditional electrospinning method. Magnetic and transport measurements indicate that the physical properties of the LSMO nanowires depend sensitively on the doping concentration. At the optimum doping, the LSMO wires are ferromagnetic at room temperature with a metal-insulator transition temperature close to room temperature. Magnetic force microscopy studies are also performed to provide a microscopic view of these ultra-long nanowires.

A FACILE CHEMICAL SYNTHESIS of PENTADEOXYRIBONUCLEOTIDE d-TGGGT via PHOSPHOTRIESTER METHOD

In this paper,we report the chemical synthesis of oligonucleotide d-TGGGT using phosphotriester method.The protected pentamer d-MmtTGibGibGibT(=p-ClC6H_4-O(O)P)was deblocked by treatment with concentrated ammonium hydroxide and 80% acetic acid.The pure d-TGGGT obtained by chromatorgraphy on DEAE-Sephadex A-25 and Q-Sepharose FF could be hydrolyzed completely and confirmed by base ratio.