Predicting surface quality of γ-TiAl produced by additive manufacturing process using response surface method

Electron beam melting (EBM) has been found to be a promising technology for producing complex shaped parts from gamma titanium aluminide alloys (γ-TiAl). The parts produced by this process are projected to have dimensions very close to the desired final shapes. However, the surface roughness of the parts produced by EBM is excessively rough. In many applications, it is necessary to improve the quality of manufactured parts using a convenient post process. This paper determines process parameters of end milling when it is used as a post process for the parts produced by EBM. Design of experiments has been used to study the effect of the selected input parameters of end milling (spindle speed, feed rate, depth of cut and coolant type) on the surface roughness of γ-TiAl parts. Response surface methodology is used to develop a predictive model for surface roughness. Effects of the selected milling process are investigated. This paper also optimizes the selected process parameters to minimize the value of the obtained surface roughness.     

Random vibrations of cantilevered composite beams with torsion-bending coupling

The forced-vibration problem of a layered composite cantilevered beam which includes the effects of torsion and warping is solved using a third-order shear deformation theory. The solution of the free-vibration problem in conjunction with the solution of its adjoint is used to solve for the forced response of the beam. This forced-vibration solution is used to calculate the displacements, zero-crossing rates and normal and transverse shear stress responses for beams subjected to temporally and spatially varying random transverse loads. The effect of including or excluding the effects of shear deformation on the calculated response quantities is examined for beams with different configurations. The results clearly show that the shear deformation effects cannot be ignored in the calculation of response and reliability of composite beams. Although the results are presented only for beams of uniform cross-section, the eigenfunctions developed here can be effectively used as comparison functions in a Rayleigh-Ritz type analysis of nonuniform beams.     

Activity recognition for creatures of habit

Energy storage is quickly becoming the limiting factor in mobile pervasive technology. We introduce a novel method for activity recognition which leverages the predictability of human behavior to conserve energy by dynamically selecting sensors. We further present a taxonomy of existing approaches to dynamically reducing consumption while maintaining recognition rates. The novel algorithm conserves energy by quantifying activity-sensor dependencies and using prediction methods to identify likely future activities. The approach is implemented and simulated using two activity recognition data sets, and the effects of the novel method are evaluated in terms of recognition rates, energy consumption, and prediction rates. The results indicate that switching off sensors only significantly affects prediction under extreme conditions and that these effects can be counteracted by adjusting system parameters. Large savings in energy can be achieved at very low cost, for example, recognition losses of 1.5 pp with 84.8 % energy savings for the first data set, and 2.8 pp and 89.9 % for the second.     

Antioxidant activity and contents of essential oil and phenolic compounds in flowers and seeds of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm

Alpinia zerumbet leaves and rhizomes have been extensively studied for their chemical compositions and biological activities. However, less attention has been given to its flowers and seeds. In our study, essential oil, total phenolics and antioxidant capacities assayed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and β-carotene bleaching methods were evaluated in flowers and seeds of A. zerumbet. In addition, their phenolic composition was determined by GC–MS and HPLC. 1,8-Cineol, camphor, methyl cinnamate and borneol were the major constituents in flower oils, whereas the main components in seeds oil were α-cadinol, T-muurolol, α-terpineol, δ-cadinene and terpinene-4-ol. The results showed that the hexane extract of flowers contained a significantly higher quantity of dihydro-5,6-dehydrokawain (DDK) than that of seeds. Total phenolic contents of flower and seed extracts were measured as 56.7 and 13.7 mg gallic acid equivalent per gram extract, respectively. The ethyl acetate extract of flowers and seeds possessed a high antiradical activity and prevented the bleaching of β-carotene. The HPLC analysis indicated that p-hydroxybenzoic acid, ferulic acid and syringic acid were the predominant phenolics in the ethyl acetate extract of flowers, whilst p-hydroxybenzoic acid, syringic acid and vanillin were the major phenolics in seeds.     

Development of Isatin-Based Schiff Bases Targeting VEGFR-2 Inhibition: Synthesis,Characterization, Antiproliferative Properties,and QSAR Studies

Three sets of isatin-based Schiff bases were synthesized utilizing the molecular hybridization approach. Some of the synthesized Schiff bases show significant to moderate antiproliferative properties against MCF7 (breast), HCT116 (colon), and PaCa2 (pancreatic) cancer cell lines with potency compared to reference drugs 5-fluorouracil (5-FU) and Sunitinib. Among all, compound 17 f (3-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)-1-((1-(2-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methyl)-5-methylindolin-2-one) exhibits promising antiproliferative properties against the MCF7 cancer cell line with 2.1-fold more potency than Sunitinib. However, among all the synthesized compounds, three (5-methylisatin derivatives) were the most effective against HCT116 in comparison to 5-FU. Compound 17 f exhibited the highest anti-angiogenic effect on the vasculature as it significantly reduced BV from 43 mm to 2 mm in comparison to 5.7 mm for Sunitinib and flow cytometry supports the arrest of the cell cycle at G1/S phases. In addition, compound 17 f also showed high VEGFR-2 inhibition properties against breast cancer cell lines. Robust 2D-QSAR studies supported the biological data.     

Ultrastructural and histochemical evaluation of appositional mineralization of circumpulpal dentin at the crown- and root-analog portions of rat incisors

Mineralization of circumpulpal dentin has been interpreted in such a way that predentin matrix is abruptly converted to almost fully mineralized dentin at the mineralization front. A group of investigators pointed out the existence of intermediary layer along the mineralization front of rat incisor dentin and claimed that dentin mineralization is a rather transient process. Owing to a paucity of information, however, the entity of transient mineralization of dentin has remained elusive. Here we confirmed the existence of a lightly mineralized layer (LL) along the mineralization front of rat incisor dentin, recognizable by both light and electron microscopy, in routinely processed specimens. LL less than 3?μm thick was shown to be located along the mineralization front of crown-analog dentin and tapered out toward the root analog of the incisor. Electron microscopy revealed that mineral deposition first occurred in the non-collagenous matrix of LL and that mineralization of collagen fibers took place sometime later at the conventional mineralization front. Microscopic appearance of the mineral phase of LL varied considerably depending on the histological processing of ultrathin sections, thus explaining the inconsistent interpretation of dentin mineralization in previous studies. These data suggest that mineralization of circumpulpal dentin in rat incisors proceeds in a stepwise or a transient manner, initiated by crystal deposition in the non-collagenous matrix followed by massive mineral deposition in collagen fibers at the mineralization front. The thickness of LL where only the non-collagenous matrix is mineralized may vary in relation to differences in the local non-collagenous matrix and also the rate of collagen mineralization in the respective portions of circumpulpal dentin.     

Modeling the melt blowing of viscoelastic materials

Several outstanding issues concerning modeling of melt blowing of viscoelastic materials are addressed in this work. Using a slender-jet model for the melt-blown fiber, we probe the effects of rheology by considering Newtonian, upper-convected Maxwell, Phan-Thien and Tanner (PTT), and Giesekus constitutive equations. The effects of a non-uniform shear stress along the fiber length and heat transfer are also addressed. Our results suggest that by combining the slender-jet approach with a Giesekus (or PTT) constitutive equation, useful engineering predictions can be made concerning the final fiber diameter, even when assuming a constant shear stress and neglecting heat transfer. Finally, questions related to linear stability, nonlinear dynamics, and sensitivity are explored. Steady-state fiber profiles are found to be linearly stable, and numerical simulations indicate that the predictions from linear theory can be carried over into the nonlinear regime. Sensitivity analysis reveals that disturbances are likely to become especially amplified at particular frequencies, with elasticity reducing the magnitude of the amplification but broadening the spectrum of frequencies susceptible to large amplification. This suggests an explanation for the narrower fiber diameter distributions that are observed experimentally.     

Effects of domestic violence on children's behavior problems and depression.

The Children's Depression Inventory, Child Behavior Checklist, and Youth Self-Report were completed by mothers, fathers, and their 8–12 yr old children to assess the effects of various types of domestic violence on children's behavior problems and depression. 110 Israeli children from lower-class families were identified through social service records. 33 of the children had been physically abused by their parents within the last 6 mo, 16 had witnessed spouse abuse, 30 had been both victims and witnesses of domestic violence, and 31 had experienced no known domestic violence. Overall, domestic violence had effects on child development that varied in magnitude and nature depending on the type of domestic violence and who reported the information about the child's adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

General route to vertical ZnO nanowire arrays using textured ZnO seeds

A method for growing vertical ZnO nanowire arrays on arbitrary substrates using either gas-phase or solution-phase approaches is presented. A approximately 10 nm-thick layer of textured ZnO nanocrystals with their c axes normal to the substrate is formed by the decomposition of zinc acetate at 200-350 degrees C to provide nucleation sites for vertical nanowire growth. The nanorod arrays made in solution have a rod diameter, length, density, and orientation desirable for use in ordered nanorod-polymer solar cells.     

Towards Collaborative Group Activity Recognition Using Mobile Devices

In this paper, we present a novel approach for distributed recognition of collaborative group activities using only mobile devices and their sensors. Information must be exchanged between nodes for effective group activity recognition (GAR). Here we investigated the effects of exchanging that information at different data abstraction levels with respect to recognition rates, power consumption, and wireless communication volumes. The goal is to identify the tradeoff between energy consumption and recognition accuracy for GAR problems. For the given set of activities, using locally extracted features for global, group activity recognition is advantageous as energy consumption was reduced by 10 % without experiencing any significant loss in recognition rates. Using locally classified single-user activities, however, caused a 47 % loss in recognition capabilities, making this approach unattractive. Local clustering proved to be effective for recognizing group activities, by greatly reducing power consumption while incurring a loss of only 2.8 % in recognition accuracy.