Synthesis of Nanometer-sized Mesoporous Oxide Spheres

A few hundreds nanometer-sized mesoporous silica and alumina spheres were synthesized in organic solvents. The impacts of ammonia, N, N-dimethylformamide (DMF) and stirring speed were also investigated.

Potential Applications of Nano-Scale Science and Technology in Geosciences and Experimental Studies of Nanometer-Sized Gold Adsorption on Minerals and Rocks

Potential applications of Nano-scale science and technology are discussed in mineralogy, ore deposits, cosmochemistry and environmental sciences. Adsorption of nanometersized gold was experimentally studied on a variety of minerals and rocks.

Synthesis and Luminescent Properties of Novel Nanometer-sized ScAlMgO_4:Eu^(3+) Phosphors for PDP

Novel nanometer-sized ScAlMgO4：Eu3＋ phosphors were successfully synthesized by the citric acid complexation method.The mean particle size of the obtained powders was within the range of 100～150 nm according to the SEM patterns.In ScAlMgO4：Eu3＋ showed strong characteristic red emission,of which the maximum emission peak was located at 629 nm for ultraviolet（UV） excitation.The dependence of photoluminescence intensity on Eu3＋ concentration was also studied in detail,and the emission intensity of Sc1-xEuxAlMgO4 was about 10% at optimized Eu3＋ concentration.Furthermore,the luminescence decay measurements showed that the lifetimes of Eu3＋ were in the range of millisecond.The obtained ScAlMgO4：Eu3＋ phosphors with nanometer size and excellent luminescence efficiency would be potential red phosphors in plasma display panels.

THE MECHANISM FOR NANOMETER-SIZED TiC SYNTHESIZING BY MECHANICAL & THERMAL ACTIVATION PROCESSING

A novel process for synthesizing nano-ceramics powders, named mechanical & therm al activation processing, is discussed in the present paper. It is a processing based on thermal activation in liquid phase (molten salt) after mechanical activ ation. The nanometer-sized TiC particles (15-20nm) have been synthesized by the method, and analyzed by X-ray diffraction (XRD), transmission electron microscop e (TEM), scanning electron microscopy (SEM) and energy dispersion X-ray (EDX) sp ectroscopy. An interface interaction between liquid (molten salt) and solid (fin al product particles) phases plays a dominating role for the control of product particles size. The mechanism for the formation of nanometer-sized TiC particles has been discussed.

Preparation and Gas Sensitive Properties of Nanometer-Sized SnO_(2)

Nanometer sized SnO 2 particles were prepared by a sol gel method using inorganic salt as a precursor material. Its crystallization was investigated by means of TG DTA,IR absorption spectra, X ray diffractometry and TEM as well as its resistivity change and the gas sensitivity varied with temperature were measured in various reducing gas. The results indicate that well crystallized nano sized SnO 2 with size around 15nm can be obtained at annealing temperature 600℃. The activation energy for the growth of nano SnO 2 was calculated to be 26.55kJ.mol 1 when the annealing temperature was higher than 500℃. The measurements also show that there is a peculiar resistance change varied with temperature for nano SnO 2.It has relevance to the increase in surface adsorbed oxygen. The selective detectivities to C 4H 10 and petrol can be increased when ruthenium ion was doped in nano SnO 2 as a catalyst and so do the gas sensitivity to CO,CH 4,H 2 etc. when rhodium ion was doped in.The detection to the several reducing gas can be realized when the temperature ranged from 260℃ to 400℃.

Simulation of Electrical Discharge Initiated by a Nanometer-Sized Probe in Atmospheric Conditions

In this paper, a two-dimensional nanometer scale tip-plate discharge model has been employed to study nanoscale electrical discharge in atmospheric conditions. The field strength dis- tributions in a nanometer scale tip-to-plate electrode arrangement were calculated using the finite element analysis （FEA） method, and the influences of applied voltage amplitude and frequency as well as gas gap distance on the variation of effective discharge range （EDR） on the plate were also investigated and discussed. The simulation results show that the probe with a wide tip will cause a larger effective discharge range on the plate; the field strength in the gap is notably higher than that induced by the sharp tip probe; the effective discharge range will increase linearly with the rise of excitation voltage, and decrease nonlinearly with the rise of gap length. In addition, probe dimension, especially the width/height ratio, affects the effective discharge range in different manners. With the width/height ratio rising from 1 ： 1 to 1 ： 10, the effective discharge range will maintain stable when the excitation voltage is around 50 V. This will increase when the excitation voltage gets higher and decrease as the excitation voltage gets lower. Fhrthermore, when the gap length is 5 nm and the excitation voltage is below 20 V, the diameter of EDR in our simulation is about 150 nm, which is consistent with the experiment results reported by other research groups. Our work provides a preliminary understanding of nanometer scale discharges and establishes a predictive structure-behavior relationship.

Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano‑Aerogel via Abundant Nano‑Sized Cavities and Attenuation Interfaces

Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.

Grain Size and Photocatalytic Activity of Nanometer TiO_2 Thin Films Prepared by the Sol-gel Method

Transparent anatase TiO2 nanometer thin films with photocatalytic activity were prepared via the sol-gel method on soda-lime glass. The thickness , crystalline phase, grain size, surface hydroxyl amount and so on were characterized by scanning electron microscopy (SEM) , X-ray diffraction (XRD), transmission electron microscopy ( TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer ( UV-VIS). The photocatalytic activity of TiO2 thin films was evaluated for the photocatalytic decolorization of aqueous methyl orange . The effects of film thickness on the crystalline phase, grain size, transmittance and photocatalytic activity of nanometer Ti02 thin films were discussed.

Kinetics Investigation of Sintering of Nanometer Size Metal Clusters:A Molecular Dynamics Study

The sintering process of nanometer size gold clusters is investigated by using molecular dynamics simulation in the frame of embedded atomistic method. Several molecular dynamics simulation techniques are used to observe and describe the evolution of the sintering process. The energy distribution for single cluster is examined and the snapshots of sintering process of two clusters are recorded. The evolution of sintering is also described by plotting the mass center changes with time for each cluster. The variations of kinetic and potential energy during the process of sintering are monitored and measured to analyze the dominant mechanisms of sintering from the energy point of view.

Study on Adsorption Behavior of Rare Earth Complexes on Nanometer-Size Titanium Dioxide with ICP-AES

A new method of using nanometer TiO 2 as solid phase extractant coupled with ICP AES was proposed for speciation of rare earth elements. The adsorption behavior of rare earth complexes on nanometer TiO 2 was investigated. Effect of pH value, contact time, elution solution and interfering ions on the recovery of the rare earth complexes were studied. A quantitative recovery (>90%) was found in the pH range of 4～9.0 for Eu citric, 4.5～9.0 for Eu oxine and Eu HIBA, and 6.5～9.0 for Eu 3+ . Eu EDTA can not be adsorbed in the pH range studied. There is large difference in the adsorption behavior on nanometer TiO 2 between rare earth element and its complexes. The possibility of application of nanometer TiO 2 on the speciation of rare earth element was explored.

New complex physiological findings evolve hypothesized mechanisms of Dravet syndrome

Developmental and epileptic encephalopathies(DEEs)are neurological disorders generally involving medically intractable seizures and a diverse array of comorbid neuropsychiatric delays and deficits that may severely affect cognition,mood,sleep,social behavior,movement control,learning,and/or memory.Dravet syndrome(DS),also known as Severe Myoclonic Epilepsy of Infancy.

Long-Cycle Lithium Batteries with LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) Cathodes above 4.5 V Enabled by Uniform Coating of Nanosized Garnet Electrolytes

The pursuit of high-energy cathode materials has been focused on raising the charging cutoff voltage of nickel (Ni)-rich layered oxide cathode such as LiNi_(0.8)Co_(0.1)Mn_(0.1)O2 (NCM811). However, the NCM811 suffers from rapid capacity fading upon cycling at cutoff voltage higher than 4.5 V, owing to their structural degradation and labile surface reactivity. Surface-coating with solid electrolytes has been recognized as an effective method to mitigate the performance failure of NCM811 at high voltage. Herein, the nano-sized Li_(6.4)La_(3)Ta_(0.6)Zr_(1.4)O_(12) (LLZTO) is uniformly coated on the surface of single-crystal NCM811 particles, accompanied with the long-range Ta^(5+) diffusion into the transition metal layer of NCM811 lattice. It is revealed that the LLZTO coating can not only inhibit the surface reactions of NCM811 with liquid electrolytes but also play an important role in suppressing the bulk microcracking within the NCM811 particles. The incorporation of Ta^(5+) ion expands the lattice spacing and thereby improves the homogeneity of the Li^(+) diffusion in the single-crystal NCM811, which alleviates the mechanical strain and intragranular cracks caused by nonuniform phases-transformation at high charging voltage. The synergy of surface protection and structural stabilization realized by LLZTO coating enables the NCM811-based lithium batteries to achieve a remarkable electrochemical performance. Typically, LLZTO coated NCM811 delivers a high reversible specific capacity of 202.1 mAh⋅g^(−1) with an excellent capacity retention as high as 70% over 1000 cycles upon charging to 4.5 V at 1 C.

Preconcentration of Ultra-trace Cadmium with Nanometer-size TiO_2 Colloid and Determination by GFAAS with Slurry Sampling

A novel method of ultra-trace Cd（Ⅱ） preconcentration with nanometer-size TiO2 colloid and determination by graphite furnace atomic adsorption spectrometry（GFAAS） with slurry sampling was first advanced in this paper. The adsorption efficiency of nanometer-size TiO2 colloid for ultra-trace Cd（Ⅱ） could reach above 96% in a short time when the pH value was between 5 and 6. Other problems were also studied, such as adsorption capacity, nanometer-size TiO2 colloid dosage, effect of coexistent ions. The detection limit（3σ） and the relative standard deviation （R.S.D） of this method were 4.46.103 μg/L and 1.30%（n=7）, respectively. The method was successfully applied to the analysis of environmental samples with recoveries between 93.8% and 96.4%.

Sol-gel synthesis of nanometer silicon/silicon suboxide/carbon anode material

A stacked Si/SiO_(x)/C composite anode material with carbon-coated structure was prepared by sol-gel method combined with carbothermal reduction using organic silicon.The results of X-ray diffractometry, scanning electron microscopy, and elemental analysis show that the Si/SiO_(x)/C material is a secondary particle with a porous micronanostructure, and the presence of nanometer silicon does not affect the carbothermal reduction and carbon coating.Electrochemical test results indicate that the specific capacity and first coulombic efficiency of SiO_(x)/C composite with nanometer silicon can be increased to 1 946.05 mAh/g and 76.49%,respectively.The reversible specific capacity of Si/SiO_(x)/C material blended with graphite is 749.69 mAh/g after 100 cycles at a current density of 0.1 C,and the capacity retention rate is up to 89.03%.Therefore, the composite has excellent electrochemical cycle stability.

Thin-walled and large-sized magnesium alloy die castings for passenger car cockpit:Application,materials,and manufacture

In order to effectively reduce energy consumption and increase range mile,new energy vehicles represented by Tesla have greatly aroused the application of integrated magnesium(Mg)alloy die casting technology in automobiles.Previously,the application of Mg alloys in automobiles,especially in automotive cockpit components,is quite extensive,while it has almost disappeared for a period of time due to its relatively high cost,causing a certain degree of information loss in the application technology of Mg alloy parts in automobiles.The rapid development of automotive technology has led to a higher requirement for the automotive components compared with those traditional one.Therefore,whatever the components themselves,or the Mg alloy materials and die casting process have to face an increasing challenge,needing to be upgraded.In addition,owing to its high integration characteristics,the application of Mg alloy die casting technology in large-sized and thin-walled automotive parts has inherent advantages and needs to be expanded urgently.Indeed,it necessitates exploring advance Mg alloys and new product structures and optimizing die casting processes.This article summarizes and analyzes the development status of thin-walled and large-sized die casting Mg alloy parts in passenger car cockpit and corresponding material selection methods,die casting processes as well as mold design techniques.Furthermore,this work will aid researchers in establishing a comprehensive understanding of the manufacture of thin-walled and large-sized die casting Mg alloy parts in automobile cockpit.It will also assist them in developing new Mg alloys with improved comprehensive performance and new processes to meet the high requirements for die casting automotive components.

Preconcentration and Separation of Trace Copper in Water Samples with Nanometer-Size TiO_2 Colloid and Determination by FAAS

A new absorbent of nanometer-size TiO2 colloid for Cu（Ⅱ ） was studied in this work. The adsorption rate could reach above 99% when the pH values were at the range of 5-6. The adsorption balance time, adsorption capacities, and the eluent were investigated. A novel method of trace Cu（ Ⅱ ） preconcentration and separation with nanometer-size titanium dioxide colloid and determination by flame atomic absorption spectrometry （FAAS） was advanced. The detection limit （3a） of the method was 1.15 μg · L^-1, and the relative standard deviation （R.S.D） was 1.53% （n=6）. Environmental sample experiments were also conducted to test the feasibility of the method, and it came out that the recovery rates were between 95.9% and 97.8%.

Application of Nanometer-Size Titanium Dioxide in Extreme-Trace V(Ⅴ) Analysis

The adsorption properties of nanometer-size TiO2 for V（Ⅴ ） were studied. The adsorption rate could reach above 99~ when the pH values were at the range of 4 10. The adsorption balance time was 10 min , the saturation capacity of adsorption of nanometer-size TiO2 to V（Ⅴ） was 6.43 mg per gram. Using 2 mL 1.5 mol · L^-1 NaOH as elution, we found the elution rate could reach 95%. A novel method of extreme-trace V（Ⅴ ） preconeentration with nanometer-size titanium dioxide and determination by graphite furnace atomic absorption spectroscopy （GFAAS） was advanced. The detection limit（3σ）of the method was 0.61μg ·L^-1 , and the relative standard deviation was 8.1% （n=6） of 2.5μg ·L-^1 V（Ⅴ）. Environmental samples experiments were also conducted to test the feasibility of the method, and it came out that the recovery rates were between 91.2% and 102.0%.

Contract Mechanism of Water Environment Regulation for Small and Medium Sized Enterprises Based on Optimal Control Theory

The small and scattered enterprise pattern in the county economy has formed numerous sporadic pollution sources, hindering the centralized treatment of the water environment, increasing the cost and difficulty of treatment. How enterprises can make reasonable decisions on their water environment behavior based on the external environment and their own factors is of great significance for scientifically and effectively designing water environment regulation mechanisms. Based on optimal control theory, this study investigates the design of contractual mechanisms for water environmental regulation for small and medium-sized enterprises. The enterprise is regarded as an independent economic entity that can adopt optimal control strategies to maximize its own interests. Based on the participation of multiple subjects including the government, enterprises, and the public, an optimal control strategy model for enterprises under contractual water environmental regulation is constructed using optimal control theory, and a method for calculating the amount of unit pollutant penalties is derived. The water pollutant treatment cost data of a paper company is selected to conduct empirical numerical analysis on the model. The results show that the increase in the probability of government regulation and public participation, as well as the decrease in local government protection for enterprises, can achieve the same regulatory effect while reducing the number of administrative penalties per unit. Finally, the implementation process of contractual water environmental regulation for small and medium-sized enterprises is designed.

Preparation, Characterization and Photocatalytic Activity of Fe, La Co-doped Nanometer Titanium Dioxide Photocatalysts

A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox- ide （TiO2） have been successfully prepared by template method using Fe（NO3）3.9H2O, La（NO3）3.6H2O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N2 adsorption-desorption measurement were employed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solution. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m2/g. It was shown that the Fe and La co-doped nano-TiO2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of co-doped nano-TiO2 was also confirmed, the photocatalytic activity of codoped nano-TiO2 remained above 89.6% of the fresh sample after being used four times.

Preparation and Characterization of Nanometer TiO_2 by Hydrolysis Precipitation Method

Nanometer TiO 2 powders were obtained from TiOSO 4 and studied by XRD, TEM and BET. The result indicated that pH and heat treatment temperature have great effects on their grain size and crystal phase structure. Annealed at 500 ℃, nanometer TiO 2 with a specific surface area of 101.39 m 2 ·g -1 and a grain size about 10 nm were obtained(pH=5); and with a specific surface area of 95.48 m 2 ·g -1 and a grain size about 30 nm were obtained(pH=10). The research indicated that crystal phase transformation of rutile at 750 ℃made great promotion in grain size growth.