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In this paper, a novel bat algorithm with an asymmetrical weighed variational method (AWVM-BA) is proposed. The proposed algorithm employs the BA with a point-to-point modified asymmetrical variation above the three-dimensional flying region, which treats the space as sets of geodesics in a second order Euclidean weighed warped space. Mutation and the local selection procedure can be avoided at the same time, which solves the problem of a local optimum in concave regions. As shown in the results, the proposed algorithm does not have much impact on the calculation complexity and time in convex regions. It can greatly reduce the calculation time and avoid local optimization in concave regions. The disadvantage of the proposed algorithm is that the iteration number increases comparatively faster with the increase in the deviation of the wind speed. Therefore, it requires a higher hardware calculation ability.

Glucagon-like peptide-1 (GLP-1) is mainly secreted by preglucagon (PPG) neurons, which play important roles in modulation of neuronal activity and synaptic transmission through its receptors. In this study, we here studied the effect of GLP-1 on parallel fiber-Purkinje cell (PF-PC) synaptic transmission in mouse cerebellar slices, by whole-cell patch-clamp recording technique and pharmacology methods. In the presence of GABAA receptor antagonist, bath application of GLP-1 (100 nM) enhanced PF-PC synaptic transmission, which expressed an increase in amplitude of evoked excitatory postsynaptic synaptic currents (eEPSCs) and a decrease in paired-pulse ratio (PPR). GLP-1 induced enhancement of eEPSCs was abolished by a selective GLP-1 receptor antagonist, Exendin 9–39, as well as by extracellular application of a specific protein kinase A (PKA) inhibitor, KT5720. However, inhibition of postsynaptic PKA which PKI containing internal solution, failed to block GLP-1 induced enhancement of eEPSCs. In the presence of a mixture of gabazine (20 µM) and TTX (1 µM), GLP-1 receptor significantly increased the frequency of miniature excitatory postsynaptic synaptic currents (mEPSCs), but without change the amplitude of mEPSCs. The GLP-1 induced increase in the frequency of mEPSCs was blocked by Exendin 9–39, as well as by inhibition of PKA with KT5720. The results indicate that activation of GLP-1 receptor enhances glutamate release at PF-PC synapse via PKA signaling pathway, resulting in an enhancement of PF-PC synaptic transmission in vitro in mice. The finding suggests that GLP-1 plays critical role in modulation of cerebellar function by regulating the excitatory synaptic transmission at PF-PC synapses in living animals.

The cerebellum receives sensory inputs from mossy fiber-granule cell or climbing fiber pathways, and generates motor-related outputs. However, the temporal and special mechanism of the sensory information processing in cerebellar cortex is still unclear. Therefore, we here investigated the temporal-spacial mechanism between the facial stimulation-evoked field potential responses in granular layer (GL) and molecular layer (ML), by duo-electrophysiological recording technique and pharmacological methods in urethane-anesthetized mice. Our results showed that air-puff stimulation of ipsilateral whisker pad evoked successively field potential responses in GL and ML. The field potential response in GL exhibited a strong excitatory component (N1) followed by an inhibitory component (P1), while the field potential response in ML exhibited a tiny excitatory component (N1) followed by strong inhibitory component (P1). The latency of N1 was decreased with the increase of recording depth in ML, and it was the shortest in GL. Notably, the latencies of P1 in GL and ML were similar regardless the relative recording sites. Furthermore, blocking α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated parallel fiber excitatory inputs by application of AMPA receptor antagonist, NBQX prevented P1 in both ML and GL. Moreover, application of GABAA receptors antagonist, gabazine simultaneously abolished P1 in both ML and GL. These results indicate that the facial stimulation evoked a simultaneous GABAergic inhibition in both ML and GL via mossy fiber-GC-parallel fiber pathway, suggesting that the sensory stimulation simultaneously evoked excitation of molecular layer interneurons (MLIs) and GL Golgi cells in cerebellar cortex.

The magnetic properties of single crystals Si, SrTiO3, LaAlO3, MgO, and (La,Sr)(Al,Ta)O3 were investigated systematically. Three origins of the magnetizations of these crystals, namely, an intrinsic diamagnetic, a paramagnetic, and a ferromagnetic contribution, have been found to influence the magnetic signals measured on the crystals, in some important application scenarios such crystals being served as substrates with the magnetic thin film epitaxially grown on. Quantitative analyses methodologies were developed and thorough investigations were performed on the crystals with the intrinsic materials parameters thus revealed, especially that the intrinsic diamagnetic susceptibility differential dχ dia/dT were identified quantitatively for the first time in SrTiO3, LaAlO3, MgO, and (La,Sr)(Al,Ta)O3. The paramagnetic contribution is found to be the key in terms of the magnetic properties of the crystals, which in turn is in fact a consequence of the 3d impurities doping inside the crystal. All the intrinsic materials parameters are given in this paper as datasets, the datasets are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00028.

In this paper, a miniaturized dual-polarized ultra-wideband (UWB) Vivaldi antenna with compact structure is presented. The application of conventional Vivaldi antenna is limited by large dimension in different fields. Therefore, a novel structure with two semi-elliptical slot edges and four resistors is employed to miniaturize the size of the antenna in this paper. The results of the simulation show that the proposed antenna impedance bandwidth of $\mathrm{VSWR} \leq 2$ is 2.2∼13.7 GHz, and the size of proposed antenna structure is reduced to $35.8\ \mathrm{mm} \times 29.2\ \mathrm{mm}$ . Besides, two Vivaldi antennas which are fed separately by microstrip-slot line balun are orthogonally placed to achieve dual-polarization with port isolation better than 16.1dB. The simulated results show that good dual-polarization and miniaturization is obtained, and the proposed antenna is a good candidate for engineering applications.

To solve the problems encountered in practical processes of magneto-optical sensing, the infinitesimal distributed-parameter model and finite-element accumulation of different dielectric properties of micromaterials were used to describe the evolution of light polarization states, instead of the previously commonly used method of lumped-parameter simulation, thus essentially explaining the mechanism of sensing, magneto-optical effects, and related factors, and achieving multiphysics coupling using the COMSOL finite-element analysis method. Considering the cases of the Faraday effect without and with line birefringence, the magneto-optical effect and output characteristics of an infinitesimal magneto-optical sensor were simulated and studied. The results verified the effectiveness of the infinitesimal sensor model. Because the magnetic field, stress, and temperature changes alter the dielectric properties of magneto-optical materials, the finite-element accumulation method lays a good foundation for research on theoretical analysis and performance of magneto-optical sensors affected by factors such as the magnetic field, temperature, and stress.

Through analyzing fault information of the home and abroad CNC equipment used in the same auto parts production, the fault data fitting were implemented in this paper. Assuming time between failure probability density function and the empirical distribution function follow the Weibull distribution, A reliability statistical model was built using the least squares method and a linear parameter distribution model regression method. The linear correlation test and the Weibull distribution fault interval obtained show the fact that both the home and abroad equipment are subject to the two parameter Weibull distribution, and after calculating the three indexes of reliability assessment, a conclusion can be made that the reliability of domestic equipment in the study is slightly lower than that of foreign equipment.

Aflatoxins (AFs) are a series of highly toxic and carcinogenic secondary metabolites. In order to eliminate AFs contamination, biological control is one of the more promising techniques. In this study, we describe the optimization of media nutrients for the selected biocontrol bacterium, Lysinibacillus xylanilyticus strain BPM1. The strain was isolated from the peanut hulls in Shandong Province, China and exhibited antagonistic activity against aflatoxins. Maltose and sucrose were identified as best carbon source, while soya peptone and yeast extract as nitrogen source led to the highest OD600 observations. Medium composition was optimized using Plackett-Burman design, which was applied to find the key ingredients. The results revealed that the most significant two factors which were more effective in the fermentation of L. xylanilyticus BPM1 were soya peptone and yeast extract.

Chitinase is one of the most important mycolytic enzymes with industrial significance, and produced by a number of organisms. A chitinase producing isolateSerratia marcescensJPP1 was obtained from peanut hulls in Jiangsu Province, China, and exhibited antagonistic activity against aflatoxins. In this study, we describe the optimization of medium composition with increased production of chitinase for the selected bacteria using statistical methods: Plackett-Burman design was applied to find the key ingredients, and central composite design of response surface methodology was used to optimize the levels of key ingredients for the best yield of chitinase. Maximum chitinase production was predicted to be 23.09 U/mL for a 2.1-fold increase in medium containing 12.70 g/L colloidal chitin, 7.34 g/L glucose, 5.00 g/L peptone, 1.32 g/L (NH4)2SO4, 0.7 g/L K2HPO4, and 0.5 g/L MgSO4·7H2O. Polymerase chain reaction (PCR) amplification of the JPP1 chitinase gene was performed and obtained a 1,789 bp nucleotide sequence; its open reading frame encoded a protein of 499 amino acids named as ChiBjp.

Serratia marcescens strain JPP1 was isolated from the peanut hulls in Jiangsu Province, China. The strain exhibited antagonistic activity against aflatoxins production and chitinolytic activity by producing chitinases. For chitinase production glucose was identified as best carbon source, peptone as organic nitrogen source while ammonium sulphate as the best inorganic nitrogen source led to the highest chitinase activity. Chitin served as an essential inducer and chitinase production reached the peak level after 1.2% of chitin concentration. The crude chitinase was highly thermostable and had activity in broad pH (2-11) and temperature (30-90°C) range. Ca and Mn ions enhanced the chitinase production, while Na and K were of inhibitory action not more than 5%, and Cu, Zn and Fe ions resulted in drastic enzyme inhibition ranged between 63.7 to 70.5%. Addition of EDTA, mercaptoethanol and Tween 80 had positive effect on chitinase production while SDS decreased the chitinase production by S. marcescens JPP1.

The present paper investigates the 3D medial axis transform of objects bounded by freeform surfaces via the saddle point programming method, a mathematical programming approach used to identify the saddle points of a function. After exploring the local geometry and saddle point property of 3D medial axis transform, the mathematical programming method is employed to construct the saddle point programming models. Based on the optimality conditions that the optimal solutions should satisfy, a generic algorithm for computing various medial axis points is developed. In order to identify the junction points and localize the problem, the boundary and the skeletal curves are divided into skeletal segments, and it is proved to be efficient and accurate by numerical examples.

We successfully deposited the purely c-axis oriented Fete thin film, which shows superconducting transition in electrical resistivity about 12 K, by using pulsed laser deposition method. The electrical transport measurements of the thin film are studied with magnetic fields up to 14.0 T. thermally activated energy is analyzed using simple conventional Arrhenius relation and more precise relation who is closer to experimental results. Besides, the upper critical magnetic field and the vortex glass transition temperatures for the Fete thin film are studied.

with the higher mobility in many developing country, the vehicle volume, vehicle use frequency are rapidly increasing, driving skill training becomes one key factor for vehicle security and use quality. By the comprehensive application of electron, computer, network technology, the supervision, control and guidance can be done to realize the intelligent dynamic management in driving training and standardized test, which promotes the students to obtain the optimal training effect in the possible shortest time, to provide a method to improve the overall driving quality.

China logistics industry is in a very high degree of marketization, which enterprises are uneven in scale and level, presenting with the scattered, weak, disordered and other typical features. Additionally, for lack of information platform and prefect industry management, the whole industry service quality is low; the logistics collaboration between the supply and demand becomes more difficult. Based on the SOA mode, this paper studies the regional logistics integration structure, regional logistics resource optimization. Combined with case study, the logistics business process based on SOA integration will promote a new way for the development of regional logistics industry.

In this paper, we present a novel surface modeling scheme based on an envelope template. A two-parameter family of interpolating surfaces is generated by repeated bicubic interpolation of the given data points, and then a solution to the envelope condition and the envelope of the family are constructed. The continuity conditions of two adjacent patches along the common boundary are derived by analyzing the geometric properties of the envelope patch. In order to facilitate surface modeling, an envelope template is constructed, which has many desirable advantages including simple structure, good local features and so on. G^2 or C^2 composite surfaces can be obtained utilizing the envelope template sweeping over the data points.

Polysaccharides extracted from fruiting body and mycelia of higher fungi have been found to show various biological activities. Traditionally, these polysaccharides are manufactured by the hot water extraction method. Low polysaccharide yield is the disadvantage of this method. This paper reports the optimal conditions to manufacture polysaccharide with high-yield from Hypsizigus marmoreus mycelia using enzymatic hydrolytic extraction method. Neutral protease was selected as the most cost efficient among six enzymes. The uniform design was further conducted to optimize the enzymatic hydrolytic extraction conditions, and a regression model was constructed to predict polysaccharide yield. The optimized procedures was that 2% (w/w) of neutral protease was added into hydrolytic solution and incubated for 4 h at 43°C, then extracted one time at 100°C for 1 h. Under optimized procedures, the measured polysaccharide yield was 15.73±0.15 (mg/g), which was very close to the predicted value of 16.65 (mg/g). The results validated the accuracy of the regression model and the optimized procedure. When following the optimized procedures, polysaccharide yield was raised 75.0% over that before optimization, and increased by 122.5% and 104.8% over hot-water extraction and microwave assisted extraction methods respectively. This was the first study to apply uniform design for optimizing high yield manufacture of mycelia polysaccharides by enzymatic hydrolytic extraction. We concluded that enzymatic hydrolytic extraction was a simple, high yield method to manufacture polysaccharides from mushroom mycelia and might be used widely in polysaccharide-derived functional foods production.

Bacillus subtilis is potential to play an important role on biological control of aflatoxin-producing fungi. The liquid fermentation medium of Bacillus subtilis LN for production of bioactive metabolites inhibitory to mycelial growth and aflatoxin biosynthesis was optimized by single factor experiments. The results showed that optimum carbon source was glucose, the optimum nitrogen source was soy peptone, and the optimum inorganic salt was MgSO4.These screened optimal carbon, nitrogen and inorganic salt sources could be used for high yield fermentation of bioactive metabolites for developing biopesticide against aflatoxin contamination in foods.

Ypsizigus marmoreus is a newly cultivated medicinal and edible mushroom with higher antitumor activity. In this paper, a uniform design was used to optimize the medium formula with four factors each at six levels, and a regression model was constructed to predict the antitumor exopolysaccharide production. The optimal concentrations for the enhanced exopolysaccharide production were determined as 30% (w/v) glucose, 8.4% (w/v) soybean peptone, 3% (w/v) KH2PO4and 30% (w/v) sweat potato flour. Subsequent experiment confirmed the validity of the model. Under the optimal condition, exopolysaccharide yield reached 3.39g/L in shake-flask culture, which was 3.53 fold higher than that obtained in the basic medium. The results highlight the future application of optimized medium for high yield production of antitumor exopolysaccharide by fermentation of Hypsizigus marmoreus.

A label free impedimetric immunosensor for the determination of aflatoxin B1 (AFB1) was fabricated by immobilizing anti-AFB1 onto Poly o-phenylenediamine (PoPD) electropolymerized film modified gold electrode by glutaraldehyde (GA) cross-linking. An electrochemical interfacial modeling of biomolecular recognition was recommended and reasonably interpreted. EIS technology was employed for the quantitative determination. The linear detection concentration ranges of AFB1 were 0.03~0.1 μg/mL and 0.1~0.7 μg/mL. The detection limit was 2.8×10-8μg/mL. The immunosensor could be reused more than 10 times when renewed by HCl-Glycine buffer solution (pH 2.6).

This paper presents a saddle point programming approach to compute the medial axis (MA). After exploring the saddle point properties of the medial axis transform (MAT), the mathematical programming method is employed to establish the saddle point programming model of the MAT. By using the optimal conditions, i.e., the number and distribution of the tangent points between the boundary and medial axis disk, the one- and two-dimensional saddle point algorithms are developed. In order to determine the branch point, it is better to consider its generating mechanism. Here, we identify the branch point according to the sudden changes of the solutions to the one-dimensional saddle point algorithm. Hence, all the regular and irregular points of MA can be computed by a general algorithm, and it is proved to be efficient and accurate by the numerical examples.

The Basic Curvature Equations of Locally Tool Positioning (BCELTP) are an accurate description of the relationships between the second order approximations of the cutter surface, the tool envelope surface and the designed surface, which was proposed in our previous paper [Gong Hu, Cao Li-Xin, Liu Jian. Second order approximation of tool envelope surface for 5-axis machining with single point contact. Computer-Aided Design 2008;40:604-15]. Based on them, for a given tool path with single cutter contact point, a new local optimization method of tool positions is presented to maximize the machining strip width by minimizing the relative normal curvature between the tool envelope surface and the designed surface. Since the BCELTP are accurate analytical expressions, the proposed optimization method of tool positions is accurate and effective in computation. Furthermore, another new optimization method of tool positions based on a dual-parameter envelope is subsequently proposed. The most interesting point is that it will result in the same results as the method based on the BCELTP. It also proves the correctness of the method based on the BCELTP from a different angle. Finally, several examples are given to prove its effectiveness and accuracy.

Based on differential geometry, the contact problems of two surfaces are discussed in this paper. The relationship between the contact status of two surfaces and that of offset surfaces are also analyzed. For a 5-axis NC machining, some research such as optimization of cutter location and calculation of the geometrical cusp height are important. The research results indicate that the relative normal curvature is an important geometrical invariant for describing the contact state of two surfaces. For point contact two surfaces, the calculation equation for the second order remained error is given. For line contact two surfaces, the condition of the second order line contact is that the principal directions and curvatures of the two surfaces are the same along the contact curve. If two surfaces keep the second order line contact, their two offset surfaces will also keep the second order line contact, and their third order remained errors are also uniform with that of the two offset surfaces.

For 5-axis machining with single point contact, this paper proposes a method to calculate second order approximation of the tool envelope surface by using only one tool position. As we known, the true machining errors are deviations between designed surface and tool envelope surface. But it is impossible to determine the whole shape of the tool envelope surface before all tool positions are obtained. Hence, it is difficult to position the tool individually and consider true errors at the same time. Basic Curvature Equations of Locally Tool Positioning (BCELTP) are presented to solve this problem in some degree. By using them under some special conditions, given one tool position, the local shape (second order approximation) of the tool envelope surface can be calculated precisely at the corresponding cutter contact point. These equations make it convenient to adjust the tool position individually until true errors are reduced in some degree. So, they are useful for optimizing tool positions locally. Finally, some examples are given to verify the correctness and practicability of theory.

In this paper, we begin our research from the generating theory of the medial axis. The normal equidistant mapping relationships between two boundaries and its medial axis have been proposed based on the moving Frenet frames and Cesaro's approach of the differential geometry. Two pairs of adjoint curves have been formed and the geometrical model of the medial axis transform of the planar domains with curved boundaries has been established. The relations of position mapping, scale transform and differential invariants between the curved boundaries and the medial axis have been investigated. Based on this model, a tracing algorithm for the computation of the medial axis has been generated. In order to get the accurate medial axis and branch points, a Two_Tangent_Points_Circle algorithm and a Three_Tangent_Points_Circle algorithm have been generated, which use the results of the tracing algorithm as the initial values to make the iterative process effective. These algorithms can be used for the computation of the medial axis effectively and accurately. Based on the medial axis transform and the envelope theory, the trimmed offset curves of curved boundaries have been investigated. Several numerical examples are given at the end of the paper.

The offset approach of machining free form surface with cylindrical cutter is described in part 1 of this paper. This approach can also be used for other type of cutters, such as toroidal cutter, filleted end mill or drum cutter. From the point of view of the geometry, all these cutters can be called toroidal cutters. Based on this approach, the geometrical theory of machining free form surface by toroidal cutter in 5-axis NC machine tool is investigated in this paper. The process of enveloping machining free form surface has been converted into a line contact problem between the tracing surface of the circle and the offset surface of machined surface. The condition of the second order line contact and the third order osculating contact between the cutter surface and the machined surface is given. The orientation of the toroidal cutter and geometrical remained errors are calculated. By means of the proposed machining method, the machining precision and the efficiency can be improved, and the potential capacity of the 5-axis NC machine tools could be exploited. A numerical example is provided at the end of this paper for illustration.

An optimized positioning procedure for flank milling ruled surfaces with cylindrical cutter is described in the paper. The tool axis trajectory surface is a ruled surface, which is generated by moving the tool axis. The proposition that the envelope surface of cylindrical cutter is the offset surface of tool axis trajectory surface is proved using kinematics approach. It is a complement of Bedi's [Bedi S, Mann S, Menzel C. Flank milling with flat end cutter. Comput Aided Des 2003; 35:293-300] analysis about the envelope surface of cylindrical cutter. Subsequently, we get another proposition that the deviation at extremum point between the designed surface and the envelope surface of cylindrical cutter is equal to that between the offset surface of designed surface and the tool axis trajectory surface. Based on this proposition, we propose three points offset (TPO) strategy to approximate the offset surface. In order to reduce errors further, a simple least square approximation scheme is established to make the tool axis trajectory surface fit the offset surface of designed surface as much as possible. By solving the linear system of equations, the tool axis trajectory surface is deformed. Simultaneously, the corresponding envelope surface is deformed to approximate the designed surface better. Two examples are given to verify the effectiveness of the developed 5-axis flank milling technique.

Based on Cesaro's approach in differential geometry, the continuous and discrete mapping models are established in this paper, which are effectively applied to study of the pitch curves, the velocity-ratio function, the rolling characteristic and the “polygon” effect, etc. in the variable-ratio chain/belt drives. Some important conclusions are obtained. Several numerical examples are given at the end of the paper.

Multilayers of Y-type bilayers of pure and mixed erbium palmitate(EP), nonadecanate(EN) and behenate(EB) on CaF2 substrates were prepared by conventional Langmuir-Blodgett (LB) method. It is demonstrated that two systems composed of alternating bilayer of different fatty acid salts are unidimensional superlattices. These LB films were characterized by means of x-ray photoelectronic Spectrometry (XPS), FTIR and x-ray diffraction (XRD) measurements.

The increasing commercial significance of natural polysaccharides for use in medicinal products is stimulating the development of efficient and easy scale-up techniques for polysaccharide purification. In this research, the crude polysaccharides from submerged cultivation broth of Hypsizigus marmoreus were purified using radial flow chromatography (RFC), and the antiproliferative activity of the purified fractions was evaluated in vitro. DEAE Sepharose CL-6B was selected to be packed in the RFC column based on its good resolution, physical stability, and low cost. Compared with axial flow chromatography (AFC), an efficient chromatographic process with significantly less time and buffer consumption but yielding higher polysaccharide recovery and resolution was established in RFC, which could clearly purify the crude polysaccharides into different fractions. An acceptable linear scale-up effect of RFC from 100 to 500 mL was successfully achieved without loss of resolution and enhancement of time consumption. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays in cell cultures indicated that the purified polysaccharide fractions possess moderate antiproliferative activities in three different human cancer cell lines, but have significantly lower cytotoxicity in normal human cell lines in vitro. Among the polysaccharide fractions, the main purified acidic fraction W-I could be considered as a novel potential antitumor agent candidate for several tumors, especially for human alveolar epithelial tumors. This research confirmed for the first time that RFC would be a new fast and efficient tool for purification of polysaccharides into different fractions, both at laboratory and commercial scales. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:872–878, 2014

Mn2+-doped ZnS nanoparticles and Mn2+-doped ZnS nanoparticles coated with a shell of ZnS were prepared in reverse micelles. Mn2+ emission at 580 nm in the coated nanoparticles was seven times stronger than that in the uncoated ones. Ultraviolet light treatment enhanced the luminescence at 580 nm in the uncoated nanoparticles, but led to no luminescence enhancement in the coated ones. Some calculations indicated that Mn2+ ions were not randomly distributed in the particle, but preferred to occupy the sites close to the surface. The experiment results indicated that ZnS shell and UV treatment could block the nonradiative transition paths and led to the enhancement of luminescence.

Acetylene hydrogenation on both the perfect and oxygen defective anatase TiO(2)(101) surfaces supported Pd(4) cluster has been studied using density functional theory calculations with a Hubbard U correction (DFT + U). The adsorbed Pd(4) cluster on the perfect surface prefers to form a tetrahedral structure, while it likely moves to the oxygen defective site to form a distorted tetrahedral structure by removing a bridging oxygen atom. For the defective surface, it exhibits a stronger ability to capture Pd(4) cluster as charge transfer is significantly performed due to the oxygen deficiency. Moreover, it is found that the oxygen defective surface shows higher activity for acetylene hydrogenation, and the possible reason may lie in the weaker adsorption strength between the Pd cluster and the adsorbed molecules on the defective surface as compared to the case on the perfect surface.

In the present paper, ZnS : Ag nanoparticles were prepared with simple chemicals by hydrothermal method. XRD patterns indicated that the products have cubic zinc blende crystal structure. The particle diameters were calculated using the Scherer's formula, and the particle size showed a nonlinear increase with the rise of reaction temperature. TEM images demonstrated the approximate sphere shapes of products, and the crystal sizes approached the estimated ones respectively. The luminescence properties were investigated with PL and PLE spectra. Emission peaks were at about 450 nm. This emission was ascribed to the recombination between the sulfur vacancy-related electron trap donor having an energy level just below the conduction band and the Ag-related hole trap acceptor above the valence band. Excitation peaks were at about 333 nm, and the excitation was attributed to the near-band-edge absorption of ZnS matrix. The luminescence intensity was strongly influenced by the reaction temperatures and time. It increased, decreased, and then increased again with the rise of reaction temperature, and increased then decreased with the increase in reaction time. ZnS : Ag nanoparticles synthesized at 200 degrees C for 6 hours have a well luminescence intensity.

Core-shell structured ZnS : Cu/ZnS nano-particles and Cu2+ -doped ZnS nano-particles without any shell were prepared, and the effect of ZnS shell on the luminescence properties of ZnS : Cu2+ nano-particles was studied. The observed emission peak at 450 nm was assigned to the recombination of an electron from the shallow delocalized donor levels at the t2 level of Cu2+. The ZnS shell did enhance the luminescence at 450 nm, which resulted from the reduction of nonradiative recombination sites.

Mn(2+)-doped ZnS nanoparticles were prepared in reverse micelles and were coated by a shell of ZnS. The optical properties of the coated Mn(2+)-doped ZnS nanoparticles were studied and compared with those of the uncoated ones. The results indicate that Mn2+ ions emission at 580 nm in the coated nanoparticles was much stronger than that in the uncoated ones. The excitation spectra of the uncoated nanoparticles shifted to the red with the time after the initial preparation, while those of the coated ones changed little, which indicate that the coated nanoparticles had better stability than the uncoated ones.