Fine Uniformity Research Articles

A quasi-two-dimensional fluid experimental apparatus based on tank-in-tank configuration.

The fluid tank is an essential facility for experimental research on fluid mechanics. However, owing to the hydrostatic fluid pressure, a fine uniformity of the narrow channel is difficult to be maintained in a tall narrow-channel tank. To address this issue, we proposed a quasi-two-dimensional fluid experimental apparatus based on a "tank-in-tank" configuration and built with an outer tank and an inner tank. The outer tank was cuboid-shaped and used to load the fluid medium, while the inner tank, consisting of two parallel glass plates, was embedded into the outer tank and served as the experimental channel. The hydrostatic pressure acting on the channel was balanced so that a high level of uniformity was maintained over the whole channel. The available height and width of the channel were 2800 and 1500mm, respectively, while its gap distance could be adaptive from 0 to 120mm. Experimental research on motion characteristics of circular disks falling in the quasi-2D channel was implemented to investigate the effects of the falling environment and disk geometry. Four distinct falling types were observed, and the wake flow fields of the falling disks were visualized. The Reynolds numbers of falling disks ranged from 400 to 63 000 presently. Chaotic motion and regular motion were demarcated at Re ≈ 30 000. An analytical model was established to predict the final average falling velocity and Reynolds number. Finally, potential directions for future research and improvements to the apparatus were suggested.

Electroless plating Cu-Co-P polyalloy on UV/ozonolysis irradiated polyethylene terephthalate film and its corrosion resistance

High corrosion resistant Cu-Co-P coatings were firstly prepared on polyethylene terephthalate (PET) substrate by electroless plating in combination with UV/ozonolysis irradiation under optimized cobalt sulfate heptahydrate concentration, pH value, plating temperature and time. The copper polyalloy/PET composite can be obtained in three steps, namely: (i) the generation of oxygen-containing functionalities (carboxylic groups) onto PET surface through UV irradiation combined with ozone, (ii) Cu seeding catalysts were obtained after being immersed into cupric citrate and NaBH4 solutions subsequently, and (iii) Cu-Co-P polyalloy metallization using electroless plating bath. Attenuated total reflection fourier transformation infrared spectrometer (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), water contact angle measurement and energy dispersive X-ray analysis (EDAX) were utilized to track the surface changes during the whole process. The electroless plating conditions were optimized by an orthogonal experiment (L9(3)4) for Cu-Co-P coating as follows: CoSO4·7H2O addition of 0.08M, pH value, plating temperature and time were set on 10.0, 35°C and 25min, respectively. Under the optimal conditions, copper polyalloy possessed high adhesive strength and the lowest surface resistance (8.06Ω/sq), while maintaining reliability even after over 1000 times of bending and mechanical stress. The results of scanning electron microscope (SEM) and atomic force microscope (AFM) measurements showed that Cu-Co-P layer formed on PET surface was imparted with fine uniformity and high compactness. Electrochemical test revealed the optimized Cu-Co-P coatings exhibited high corrosion resistance in NaCl, NaOH and HCl solutions, respectively. The excellent electromagnetic interference shielding effectiveness (EMI SE >99.999% at frequency ranging from 30MHz to 1000MHz) of copper polyalloy/PET composites was confirmed by the spectrum analyzer. Therefore, this copper polyalloy will have potential applications in microelectronics packaging and coatings for anti-corrosion and electromagnetic interference shielding.

A microwave-triggered controllable drug delivery system based on hollow-mesoporous cobalt ferrite magnetic nanoparticles

Facile synthesis and smart designs of multifuctional nanocarriers would make them more potential in the practical application of drug delivery for cancer treatment. In this study, we synthesized hollow-mesoporous cobalt ferrite (H-mCoxFe3−xO4) nanoparticles by a cetyltrimethylammonium bromide (CTAB)-assisted solvothermal method. The resulting monodisperse CoxFe3−xO4 microspheres are 280 nm in diameter with fine uniformity and hollow-mesoporous structure, and they possess a fairly high surface area of 58.03 m2/g, a pore volume of 0.13 cm3/g, an average pore size of 7.21 nm, and are suitable for drug loading. This material has a high magnetization saturation value (42.2 emu/g) for drug targeting and its sodium chloride suspension could raise to 50 °C from room temperature in 180 s. The drug release process shows that the release rate under the microwave irradiation was faster than that under stirring condition, and about 64% VP16 was released after six on/off microwave treatment cycles. So these multifunctional H-mCoxFe3−xO4 nanoparticles with single material are expected to provide the research foundation for using as drug carrier themselves for drug loading, magnetic targeting, and microwave-triggered controllable release.

Comparative Analysis of the Surface Roughness Parameters due to the Machining Uniformity

In the paper a new method has been proposed for the determining of the very fine machining uniformity over the elaborated surface and could be applied to different machined materials and machining procedures. The proposed methodology is relatively simple and is essentially formulated in the few subsequent steps: taking surface roughness 3D profile accordingly proposed scheme; estimation of the roughness statistical parameters: Rp, Rv, Rt, Ra, Rq, Rskew, Rkurt, and if need be – surface rugosity Ru; calculation of the centroid of the obtained data due to the measurement fields, calculation of the barycentre of the obtained data with the weighting variable chosen for the appropriate evaluation of the surface machining uniformity. As the main Cartesian coordinates of the centroid calculation we propose (Rskew, Rkurt), although other data organization schemes have also been provided as the example solutions. The final evaluation of the surface machining uniformity is based upon the Euclidean distance between the centroid and barycentre of the surface roughness data. The proposed method has been applied to experimental results obtained with the AFM technique used on samples of the polished AZ31 magnesium alloy. The surface machining procedure comprised of four stages performed with using different abrasive media, finally lead to the highest grade of the surface roughness.

Study on Properties of Hard Twist Cotton Yarn

Ring-spun cotton yarn and rotor-spun yarn with hard twist factor were manufactured. It shows that yarn breaking strength varies slightly with twist factor, either ring-spun yarn or rotor-spun yarn. Twist factor has little effect on yarn breaking elongation. Yarn number has effect on yarn hairiness for ring-spun yarn and rotor-spun yarn. Coarser yarn has more hairiness than fine yarn. Ring-spun yarn hairiness is higher than rotor-spun yarn. Twist factor has some effect on coarse yarn uniformity while it affects fine yarn uniformity slightly. Ring-spun yarn has higher strength than rotor-spun yarn. Rotor-spun yarn has less elongation and less hairiness than ring-spun yarn and its uniformity is better.

From the nucleation of wiggling Au nanostructures to the dome-shaped Au droplets on GaAs (111)A, (110), (100), and (111)B.

In this paper, the systematic evolution process of self-assembled Au droplets is successfully demonstrated on GaAs (111)A, (110), (100), and (111)B. On various GaAs substrates, self-assembled Au clusters begin to nucleate at around 300°C, and then, they develop into wiggly Au nanostructures at 350°C. Between 400°C and 550°C, the self-assembled dome-shaped Au droplets with fine uniformity are fabricated with various sizes and densities based on the Volmer-Weber growth mode. Depending on the annealing temperature, the size including the average height and lateral diameter and the density of Au droplets show the opposite trend of increased size with correspondingly decreased density as a function of the annealing temperature due to the difference in the diffusion length of adatoms at varied activation energy. Under an identical growth condition, depending on the surface index, the size and density of Au droplets show a clear distinction, observed throughout the temperature range. The results are systematically analyzed and discussed in terms of atomic force microscopy (AFM) images, cross-sectional line profiles, and Fourier filter transform (FFT) power spectra as well as the summary plots of the size and density.

Annealing temperature effect on self-assembled Au droplets on Si (111)

We investigate the effect of annealing temperature on self-assembled Au droplets on Si (111). The annealing temperature is systematically varied while fixing other growth parameters such as deposition amount and annealing duration clearly to observe the annealing temperature effect. Self-assembled Au droplets are fabricated by annealing from 50°C to 850°C with 2-nm Au deposition for 30 s. With increased annealing temperatures, Au droplets show gradually increased height and diameter while the density of droplets progressively decreases. Self-assembled Au droplets with fine uniformity can be fabricated between 550°C and 800°C. While Au droplets become much larger with increased deposition amount, the extended annealing duration only mildly affects droplet size and density. The results are systematically analyzed with cross-sectional line profiles, Fourier filter transform power spectra, height histogram, surface area ratio, and size and density plots. This study can provide an aid point for the fabrication of nanowires on Si (111).

Neighborhood base at the identity of free paratopological groups

AbstractIn 1985, V. G. Pestov described a neighborhood base at the identity of free topological groups on a Tychonoff space in terms of the elements of the fine uniformity on the Tychonoff space. In this paper, we extend Postev’s description to the free paratopological groups where we introduce a neighborhood base at the identity of free paratopological groups on any topological space in terms of the elements of the fine quasiuniformity on the space.

Coaxial Electrospinning with Ethanol Aqueous Solution for Preparing High Quality Zein Nanofibers

A modified coaxial electrospinning process is developed for producing thinner zein nanofibers. With ethanol aqueous solutions as sheath fluids, high quality zein nanofibers have been successfully generated using the modified process. Electron scanning microscope results demonstrate that the nanofibers have better quality than those produced by a single fluid electrospinning in terms of nanofiber diameters and their distributions. The former has an average diameter of 1230±340 nm while the later 420±140 nm under a sheath-to-core flow rate ratio of 0.267. The mechanism is proposed that an appropriate ethanol aqueous solution surrounding the core zein jet helps to retain it in a fluid state to experience a longer time and more stable electrical drawing, with little adverse influence on the zein chain entanglements in the core fluid jets and thus its electrospinnability. The modified coaxial electrospinning process described here extends the capability of electrospinning process and opens a new way to obtain thinner nanofibers of macromolecules with fine structural uniformity.

Coaxial Electrospinning with N, N-Dimethylacetamide for Preparing Methacrylate-Based Copolymer Nanofibers

A modified coaxial electrospinning process is developed for producing thinner methacrylate-based copolymer nanofibers. With Eudragit® L-100 (EL100) as a model and using a poor volatile solvent N, N-dimethylacetamide (DMAc) as sheath fluid, high quality EL100 nanofibers have been successfully generated using the developing coaxial process. SEM observations demonstrate that the nanofibers by the modified process have better quality than those produced by a single fluid electrospinning in terms of surface smoothness, nanofiber diameters and their distributions. The former has an average diameter of 240±30 nm while the later 490±170 nm. The mechanism is proposed that an appropriate DMAc surrounding to the core polymer jet helps to retain it in a fluid state to experience a longer time and more stable electrical drawing. The modified coaxial electrospinning process described here extends the capability of electrospinning process and opens a new way to obtain thinner polymer nanofibers with fine structural uniformity.

Comparison of two electrospinning processes in obtaining finer polymer nanofibers

Two different electrospinning processes (traditional single fluid one and a modified coaxial electrospinning with organic solvent as sheath fluid) are investigated in relation to their capability of producing thinner nanofibers. Both the modified coaxial electrospinning and single fluid electrospinning can produce thinner nanofibers with polyvinylpyrrolidone (PVP) as a polymer model and using a poor volatile solvent N, N-dimethylacetamide (DMAc) in different ways. However the traditional single fluid process was less effective compared to the modified coaxial process, as it suffered more from the limitation of polymer chain entanglement threshold for maintaining structural uniformity of nanofibers. Using DMAc as sheath fluid in the modified process facilitated formation of thinner nanofibers without sacrificing their quality. The mechanism should be that an appropriate DMAc surrounding to the core polymer jet helps to retain it in a fluid state to experience a longer time electrical drawing, with little adverse influence on the polymer chain entanglements. Nanofiber diameters could also be tailored in a linear manner using the modified coaxial process simply through manipulating the sheath solvent flow rates. The modified coaxial process described here extends the capability of electrospinning process and opens a new way to obtain thinner nanofibers with fine structural uniformity.

Development and Research on the Mechanism of Novel Mist Etching Method for Oxide Thin Films

A novel etching process with etchant mist was developed and applied to oxide thin films such as zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), and indium tin oxide (ITO). By using this process, it was shown that precise control of the etching characteristics is possible with a reasonable etching rate, for example, in the range of 10–100 nm/min, and a fine pattern of high accuracy can also be realized, even though this is usually very difficult by conventional wet etching processes, for ZnO and ZnMgO. The mist etching process was found to be similarly and successfully applied to ITO. The mechanism of mist etching has been studied by examining the etching temperature dependence of pattern accuracy, and it was shown that the mechanism was different from that of conventional liquid-phase spray etching. It was ascertained that fine pattern etching was attained using mist droplets completely (or partly) gasified by the heat applied to the substrate. This technique was applied to the fabrication of a ZnO thin-film transistor (TFT) with a ZnO active channel length of 4 µm. The electrical properties of the TFT were found to be excellent with fine uniformity over the entire 4-in. wafer.

CIS layer deposition through electrospray process for solar cell fabrication

A rather new technique for the deposition of CIS layer has been discussed in this paper namely Electrospray Deposition (ESD). Thin films composed of Copper–Indium–diSelenide, have been achieved using the ESD technique for the ultimate manufacture of CIS based solar cell. CIS nano-particle inks are used in the ESD process for the deposition of ∼2 μm CIS layers on ITO coated substrates whereby ITO coating can be used as the back contact of the solar cell. Different parameters affecting the ESD process and the deposited layer thickness and uniformity such as stand-off distance, flow rate and voltage have been examined as well to come up with an optimized parameter combination. Layers with fine uniformity are achieved at two different substrate speeds, 0.5 mm/s and 1.0 mm/s. The thickness of the deposited films varied from 400 nm to 2.7 μm with varying flow rate from 30 μl/h to 230 μl/h and 2.8 μm–1.3 μm with varying stand-off distance from 13 mm to 6 mm. The cost-effectiveness, room-temperature operation, environment friendliness and simplicity of ESD process with its possible integration with high throughput manufacturing processes like Roll-to-Roll process makes it an idyllic candidate for deployment in the solar cell fabrication process at a large scale.

Synthesis of large-area single-walled carbon nanotube films on glass substrate and their field electron emission properties

Large-area and homogeneous single-walled carbon nanotube (SWCNT) films have been deposited via arc discharge directly on glass substrate coated with a layer of indium tin oxide film. The characterization, by means of electron microscopy and Raman spectroscopy, shows that the as-grown films are uniformly woven and consist of SWCNT with diameters ranging from 0.82 to 1.15 nm. As a cathode material, the field emission test indicates the films have low turn-on field of ∼1.2 V/μm at 10 μA/cm 2 emission current, and high emission intensity causing luminance of about 7000 cd/cm 2 with fine uniformity. The best performing sample exhibits a constant degradation of less than 3% per hour at an emission current of around 1 mA. Measuring with the high voltage (2000 V) on the films for 2.0 h increased the field enhancement factor from 4500 to 5400 at the high field region. The results are of significance to the development of field emission display using nanoemitters.

Large-scale synthesis of nanocrystals of barium titanate and other titanates through solution-phase processes

Abstract We reported a large-scale synthesis of nanocrystals of BaTiO 3 , SrTiO 3 , PbTiO 3 , Sr x Ba 1− x TiO 3 through low-temperature and solution-phase processes without any surfactant. The series of samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Samples obtained were of high purity, consisting of nanoparticles with fine crystallinity and uniformity as well as good dispersibility in ethanol. This method might also offer an effectively new way to synthesis other titanate nanocrystals with perovskite structure in the future.

Effect of Electrodeposited Hydroxyapatite Coatings on Biomedical Titanium by Cathode Revolving

The paper deals with a kind of new method of the electro-deposition on titanium by a cathode revolves. The depositing characteristic and mechanic were studied by scanning electron microscopy and X-ray diffraction. The experimental results show that the more fine uniformity and compact calcium phosphate bioactive coatings could be produced, compared with the conventional methods. The gradient Coating, which is fine inside and porous outside, could be obtained by controlling revolving velocity. The coating would transform to the hydroxyapatite after heat-treatment. After soaking in a simulated body fluid (SBF), nano-depositions were formed on the surface of the coating, then those particles would grow up needle-like, net-like, and an apatite-like layer could be observed finally. The gradient porosity coatings produced by cathode revolving electrochemical deposition would have high anti-dissolution and bioactive.

Cozfine and measurable uniform frames

The vital role played by the cozero part of a completely regular, and hence uniformizable, frame is well known, and has been studied in the more general setting of σ-frames. Thus, to consider uniformities generated in some way by the cozero part, namely what will be called cozfine uniformities, is a natural weakening of the fine condition. Similarly, what amounts to having the cozero part complemented is also a natural condition to consider and gives rise to what will be called the measurable uniform frames. The aim of the paper is, therefore, to consider the notions of “fine”, “cozfine” and “measurable” in a frame setting. These will be shown to define reflective subcategories of uniform, or separable uniform, frames, and their behaviour relative to the complete coreflection will be discussed. The latter is of interest considering the interaction between the completion and the state of fineness which gives various compactifications. For example, the Samuel compactification may be described as the completion of the precompact coreflection of the fine uniformity.

Fine Uniformity and the Locally Finite Hyperspace Topology

It is shown that a uniformizable space $X$ is normal iff the locally finite topology ${e^\tau }$ on the hyperspace ${2^X}$ coincides with the topology transmitted by the fine uniformity of $X$. We also prove that, for $X$ normal, the topology ${e^\tau }$ is first countable only if the set of limit points $X’$ of $X$ is countably compact. Applications of these results to pseudocompactness and Atsuji spaces are given.

Fine uniformity and the locally finite hyperspace topology

It is shown that a uniformizable space X X is normal iff the locally finite topology e τ {e^\tau } on the hyperspace 2 X {2^X} coincides with the topology transmitted by the fine uniformity of X X . We also prove that, for X X normal, the topology e τ {e^\tau } is first countable only if the set of limit points X ′ X’ of X X is countably compact. Applications of these results to pseudocompactness and Atsuji spaces are given.

COREFLECTIONS INDUCED BY FINE FUNCTORS

Abstract In 1974 A. W. Hager initiated the study of metric-fine uniform spaces. It was observed that the definition of metric-fine spaces relied on the class M of metric uniform spaces and the fine functor α, which reequips every uniform space with its fine uniformity, in a rather categorical way. By substituting for M other suitable classes K and for α other suitable functors F, called fine functors here, an analogous process leads to K-F-fine spaces, which always form bicoreflective subcategories. In this paper we give a description of the associated bicoreflectors in the realm of arbitrary topological categories of H. Herrlich. As an illustration two classes of K-F-fine spaces in the category of nearness spaces are presented.