Microstructure and mechanical properties of duplex tiAl alloys containing Mn

A study has been made of the effect of Mn on the structure and compressive mechanical properties of duplex TiAl alloys. In order to clarify the separate effect of Mn and Al contents, the effect of Ti/Al ratio was also studied by analyzing the behavior of alloys with different Ti/Al ratios at the fixed Mn content. Addition of 3 at.% Mn to the binary Ti₅₃Al₄₇ alloy decreases the tetragonality and the unit cell volume of γ structure. It also promotes the formation of twin-related structure, the refinement of interlamellar spacing and grain size, and the increase in the volume fraction of lamellar grains. Increase in Ti/Al ratio at the fixed Mn content results in the further decrease in the tetragonality and unit cell volume and the refinement of grain size, while it decreases the volume fraction of lamellar grains. The modification of microstructure directly influences the compressive properties and deformation mode of duplex TiAl alloys. It has been found that Mn addition and increase in Ti/Al ratio enhance the plasticity of duplex alloys. Generation of mobile dislocations at the twin intersections has been found to occur in Mn containing alloys. Such dislocation generation at the twin intersections as well as the promotion of deformation twins in Mn containing alloys are all beneficial for improving the ductility of duplex TiAl alloys.     

Transition Metal Dichalcogenide‐Based Transistor Circuits for Gray Scale Organic Light‐Emitting Displays

Two types of transition metal dichalcogenide (TMD) transistors are applied to demonstrate their possibility as switching/driving elements for the pixel of organic light‐emitting diode (OLED) display. Such TMD materials are 6 nm thin WSe₂ and MoS₂ as a p‐type and n‐type channel, respectively, and the pixel is thus composed of external green OLED and nanoscale thin channel field effect transistors (FETs) for switching and driving. The maximum mobility of WSe₂‐FETs either as switch or as driver is ≈30 cm² V^?1 s^?1, in linear regime of the gate voltage sweep range. Digital (ON/OFF‐switching) and gray‐scale analogue operations of OLED pixel are nicely demonstrated. MoS₂ nanosheet FET‐based pixel is also demonstrated, although limited to alternating gray scale operation of OLED. Device stability issue is still remaining for future study but TMD channel FETs are very promising and novel for their applications to OLED pixel because of their high mobility and I _D ON/OFF ratio.     

Automatic and personalized recommendation of TV program contents using sequential pattern mining for smart TV user interaction

Due to the excessive number of TV program contents available at user’s side, efficient access to the preferred TV program content becomes a critical issue for smart TV user interaction. In this paper, we propose an automatic recommendation scheme of TV program contents in sequence using sequential pattern mining (SPM). Motivation of sequential TV program recommendation is based on TV viewer’s behaviors for watching multiple TV program contents in a row. A sequence of TV program contents for recommendation to a target user is constructed based on the features such as an occurrence and net occurrence of frequently watched TV program contents from the similar user group to which the target user belongs. Three types of SPM methods are presented—offline, online and hybrid SPM. To extract sequential patterns of preferably watched TV program contents, we propose a preference weighted normalized modified retrieval rank (PW-NMRR) metric for similar user clustering. In the offline SPM method, we effectively construct the sequential patterns for recommendation using a projection method, which yields good performance for relatively longer sequential patterns. The online SPM method mines sequential patterns online by effectively reflecting the recent preference characteristics of users for TV program contents, which is effective for short-sequence recommendation. The hybrid SPM method combines the offline and online SPM methods. The maximum precisions of 0.877, 0.793 and 0.619 for length-1, -2 and -3 sequence recommendations are obtained from the online, hybrid and offline SPM methods, respectively.     

Practical implementation of a depth‐feeling‐enhanced two‐plane electro‐floating display system using three‐dimensional integral images

Abstract— Although there are numerous types of floating‐image display systems which can project three‐dimensional (3‐D) images into real space through a convex lens or a concave mirror, most of them provide only one image plane in space to the observer; therefore, they lack an in‐depth feeling. In order to enhance a real 3‐D feeling of floating images, a multi‐plane floating display is required. In this paper, a novel two‐plane electro‐floating display system using 3‐D integral images is proposed. One plane for the object image is provided by an electro‐floating display system, and the other plane for the background image is provided with the 3‐D integral imaging system. Consequently, the proposed two‐plane electro‐floating display system, having a 3‐D background, can provide floated images in front of background integral images resulting in a different perspective to the observer. To show the usefulness of the proposed system, experiments were carried out and their results are presented. In addition, the prototype was practically implemented and successfully tested.     

Weierstrass-type approximation theorems with Pythagorean hodograph curves

We prove the Weierstrass-type approximation theorem that states every C¹ curve in the 2-dimensional or 3-dimensional Euclidean space or in the 3-dimensional Minkowski space can be uniformly approximated by Pythagorean hodograph curves in the corresponding space. This abundance of PH curves is another theoretical confirmation of the usefulness and the versatility of the PH curves. We also address some algorithmic aspects of proposed PH approximation schemes and their convergence rates.     

Fabrication of monodisperse silica spheres using statistical design of experiments

The statistical design of experiments was successfully carried out in order to synthesize monodisperse silica spheres using a fractional factorial design with a resolution of V. In this design, the input variables were the temperature, the concentration of NH₃, the concentration of TEOS, the methanol/n-prophyl alcohol ratio, and the distilled water. The output variables were the particle size, standard deviations, and the degree of agglomeration. Simultaneous consideration of the particle characteristics allowed for an optimum regime in the experimental conditions in addition to an understanding of the experimental variables. The concentrations of TEOS and distilled water are determined to be statistically significant variables for the controlling of the particle sizes. The size of the monodisperse silica spheres was found to be approximately 400 nm.     

Model on the microbial quality change of seasoned soybean sprouts for on-line shelf life prediction

The growth of aerobic bacteria on Korean seasoned soybean sprouts was modelled as a function of temperature to estimate microbial spoilage and shelf life on a real-time basis under dynamic storage conditions. Counts of aerobic bacteria on seasoned soybean sprouts stored at constant temperatures between 0 degrees C and 15 degrees C were recorded. The bootstrapping method was applied to generate many resampled data sets of mean microbial plate counts that were then used to estimate the parameters of the microbial growth model of Baranyi and Roberts. The distributions of the model parameters were quantified, and their temperature dependencies were expressed as mathematical functions. When the temperature functions of the parameters were incorporated into differential equations describing microbial growth, predictions of microbial growth under fluctuating temperature conditions were similar to observed microbial growth.     

Metabolomic approach to evaluate the toxicological effects of nonylphenol with rat urine

Metabolomics has focused on toxicological applications to (1) understand the mechanisms of toxicity, (2) identify novel biomarkers of toxicity, and (3) provide in vivo assessment in animal models through simple and fast methods to date. The toxicological effects of nonylphenol (NP) were evaluated after intraperitoneal injection of rats with 0, 50, and 250 mg kg(-1) day(-1) NP for four consecutive days. In the nontargeted approach, different extraction conditions were introduced to investigate the effects of NP on rats through gas chromatography/mass spectrometry (GC/MS). The GC/MS data obtained were further analyzed with partial least-squares discriminant analysis to compare toxicological effects between control and treated groups. The targeted approach was also used in combination with GC/MS to quantify endocrine hormones and to identify possible biomarkers in rat urine under optimal extraction conditions. In addition, we considered the metabolic trajectory to examine the metabolite profiles and patterns related to steroid metabolism in rats that were treated with NP, considering both treatment amount and time. The data suggest that tetrahydrocorticosterone and 5alpha-tetrahydrocorticosterone are possible urinary biomarkers of NP-induced toxicity. This metabolomic approach is a promising tool to assist with screening in toxicological studies.     

Chlorine‐Free Synthesis of Organic Alkyl Carbonates and Five‐ and Six‐Membered Cyclic Carbonates

This report presents a new, one‐pot, facile, selective and green method for methoxycarbonylation of alcohols and synthesis of five‐ and six‐membered cyclic carbonates from corresponding alcohols with dimethyl carbonate (DMC) in the presence of molecular sieves without any additional solvent and catalyst. Syntheses of bifunctional structures comprising a six‐membered cyclic carbonate with allyl ether and methacrylate groups, respectively, for different polymerization modes, were also achieved and showed reproducibility on up‐scaling the processes.

     

Selective reduction of nitric oxide by methane on cobalt-ion-exchanged synthetic clinoptilolite zeolite in oxygen-rich atmosphere

Selective reduction of NO by CH₄ in the presence of excess O₂ has been studied on cobalt-ion-exchanged synthetic clinoptilolite (Co-CLI) zeolite. The catalytic results are compared with those obtained from Co-ZSM-5 and Co-FER, the two most widely studied catalysts for this reaction. At T ≥ 500 oC, Co-CLI is much more active for NO reduction than Co-ZSM-5, but it is less active than Co-FER. However, it is found that the selectivity for CH₄ toward reacting with NO at high temperatures (T ≥ 450 oC) is higher on Co-CLI than on Co-ZSM-5 or Co-FER. On the basic of the overall catalytic results, the importance of zeolite pore size as a structural parameter influencing the activity of intrazeolitic Co²⁺ ions for NO reduction by CH₄ is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.