Shrinkage and warpage prediction of injection‐molded thin‐wall parts using artificial neural networks

This study demonstrates the successful use of back‐propagation artificial neural networks (BPANNs) in predicting the shrinkage and warpage of injection‐molded thin‐wall parts. The effects of structural parameters of a BPANN on the predictionaccuracy and the capability of a BPANN in determining the optimal process condition are also discussed. The training and testing data are obtained experimentally based on a Taguchi L₂₇ (3¹³) test schedule. The results show that the trained BPANN can successfully predict the shrinkage and warpage of injection‐molded thin‐wall parts. Comparing the prediction accuracies of the trained BPANN and C‐Mold software, it is noted that the trained BPANN predicts more accurately. In terms of determining the optimal process condition for minimizing the shrinkage and warpage of injected thin‐wall parts, the trained BPANN is also shown to give a better optimal process condition than Taguchi's method. Polym. Eng. Sci. 44:2029–2040, 2004. © 2004 Society of Plastics Engineers.     

Efficient Dispersants for TiO2 Nanopowder in Organic Suspensions

This article discusses the appropriate dispersant for titania (TiO₂) nanopowder in organic‐based suspensions. Four types of oleyl‐based dispersants, namely, oleyl alcohol, oleic acid, oleylamine, and oleyl phosphate, which have the functional groups hydroxyl (–OH), carboxyl (–COOH), amino (–NH₂), and phosphorous [–P(=O)(OH)₂], respectively, were compared for their ability to disperse TiO₂. Experimental results for zeta potential, adsorption, FT‐IR spectroscopy, and rheology, as well as theoretical calculations, indicate that dispersants with –P(=O)(OH)₂ and –NH₂ were more efficient than those with –COOH or –OH. The primary reason for this difference is related to the different interactions of TiO₂ with various dispersants and to different dispersion mechanisms. In addition to the major functional groups, –OH in the chemical structure of dispersants was important, as it might have other effects such as destabilization of the suspensions.     

VEGF and FGF2 Improve Revascularization,Survival, and Oocyte Quality of Cryopreserved,Subcutaneously-Transplanted Mouse Ovarian Tissues

This study was conducted to investigate the effect of the vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) on revascularization, survival, and oocyte quality of cryopreserved, subcutaneously-transplanted mouse ovarian tissue. Autologous subcutaneous transplantation of vitrified-thawed mouse ovarian tissues treated with (experimental group) or without (control group) VEGF and FGF2 was performed. After transplantation to the inguinal region for two or three weeks, graft survival, angiogenesis, follicle development, and oocyte quality were examined after gonadotropin administration. VEGF coupled with FGF2 (VEGF/FGF2) promoted revascularization and significantly increased the survival rate of subcutaneously-transplanted cryopreserved ovarian tissues compared with untreated controls. The two growth factors did not show long-term effects on the ovarian grafts. In contrast to the untreated ovarian grafts, active folliculogenesis was revealed as the number of follicles at various stages and of mature oocytes in antral follicles after gonadotropin administration were remarkably higher in the VEGF/FGF2-treated groups. Although the fertilization rate was similar between the VEGF/FGF2 and control groups, the oocyte quality was much better in the VEGF/FGF2-treated grafts as demonstrated by the higher ratio of blastocyst development. Introducing angiogenic factors, such as VEGF and FGF2, may be a promising strategy to improve revascularization, survival, and oocyte quality of cryopreserved, subcutaneously-transplanted mouse ovarian tissue.     

Preparation and characterization of methoxy‐poly(ethylene glycol) side chain grafted onto chitosan as a wound dressing film

Chitosan has received extensive attention as a biomedical material; however, the poor solubility of chitosan is the major limiting factor in its utilization. In this study, chitosan‐based biomaterials with improved aqueous solubility were synthesized. Two molecular weights (750 Da and 2000 Da) of methoxypoly(ethylene glycol) (mPEG) were grafted onto chitosan (mPEG‐g‐chitosan) to form a ～100‐μm‐thick plastic film as a wound dressing. The chemical structures of the mPEG‐g‐chitosan copolymers were confirmed using Fourier transform infrared spectroscopy (FTIR), and the thermal properties were characterized using thermogravimetry analysis (TGA). Their microstructures were observed using scanning electron microscopy (SEM). The other properties were analyzed via the swelling ratio, tensile strength, elongation, and water vapor transmission rate (WVTR). Biocompatibility evaluations through biodegradability, cytotoxicity, and antimicrobial effect studies were also performed. The obtained mPEG‐g‐chitosan copolymers were soluble in slightly acidic aqueous solutions (pH～6.5) at a concentration of 10 wt %. The optimal mPEG‐g‐chitosan hydrogels had swelling ratios greater than 100% and WVTRs greater than 2000 g/m²/day. Their performance against Staphylococcus aureus will be subjected to further improvements with respect to medical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42340.     

Heat Killed Lactobacillus reuteri GMNL-263 Reduces Fibrosis Effects on the Liver and Heart in High Fat Diet-Hamsters via TGF-β Suppression

Obesity is one of the major risk factors for nonalcoholic fatty liver disease (NAFLD), and NAFLD is highly associated with an increased risk of cardiovascular disease (CVD). Scholars have suggested that certain probiotics may significantly impact cardiovascular health, particularly certain Lactobacillus species, such as Lactobacillus reuteri GMNL-263 (Lr263) probiotics, which have been shown to reduce obesity and arteriosclerosis in vivo. In the present study, we examined the potential of heat-killed bacteria to attenuate high fat diet (HFD)-induced hepatic and cardiac damages and the possible underlying mechanism of the positive effects of heat-killed Lr263 oral supplements. Heat-killed Lr263 treatments (625 and 3125 mg/kg-hamster/day) were provided as a daily supplement by oral gavage to HFD-fed hamsters for eight weeks. The results show that heat-killed Lr263 treatments reduce fatty liver syndrome. Moreover, heat-killed Lactobacillus reuteri GMNL-263 supplementation in HFD hamsters also reduced fibrosis in the liver and heart by reducing transforming growth factor β (TGF-β) expression levels. In conclusion, heat-killed Lr263 can reduce lipid metabolic stress in HFD hamsters and decrease the risk of fatty liver and cardiovascular disease.     

Solvent‐ and Transition Metal Catalyst‐Dependent Regioselectivity in the [3+2] Cyclocondensation of Trifluoromethyl‐α,β‐ynones with Hydrazines: Switchable Access to 3‐ and 5‐Trifluoromethylpyrazoles

The regioselectivity of the [3+2] cyclocondensation of trifluoromethyl‐α,β‐ynones with hydrazines can be readily tuned to preferentially afford either 3‐ or 5‐trifluoromethylpyrazoles through variation of the reaction conditions. Under catalysis with copper(II) acetate (2.0 mol%), cyclocondensation proceeded smoothly to yield 3‐trifluoromethylpyrazoles with high regioselectivity. In contrast, when the reaction was conducted in dimethyl sulfoxide under catalyst‐free conditions, the formation of 5‐trifluoromethylpyrazoles was predominantly observed.

     

Properties of PVA-PSA hybrid materials prepared through the incorporation of polysilicic acid (PSA) into polyvinyl alcohol

A quick method of preparing transparent organic-inorganic hybrid material was studied. The hybrid, PVA/PSA, was prepared through incorporating the nanoscaled polysilicic acid (PSA) obtained through hydrolysis and condensation of metasilicate salt directly into a polyvinyl alcohol (PVA). The interfacial force, microstructure, and dynamic mechanical property of the hybrid were studied by means of spectroscopy (FTIR, X-ray diffraction and solid-state ²⁹Si NMR) and dynamic mechanical analysis, and the results were compared with that of the hybrids, PVA/TEOS, prepared through the traditional sol-gel process. It was found that the microstructure of PVA/PSA was different from that of PVA/TEOS because of the different preparation methods. The structures of the crystals in both hybrids were similar to that of the pure PVA. Other physical properties, such as T_g, storage modulus, tensile strength and solvent resistance of the PVA/PSA hybrid, were improved significantly with the addition of the silica content. The extent of improvement was a little lower than that for the PVA/TEOS.     

Multiple roles of color information in the perception of icon‐type images

Despite the ubiquity of icons in computing and mobile devices, the role of color in icon‐based interface design has yet to be fully elucidated. This study began by conducting a card sorting experiment to determine the importance of color in the perception of commercial icons, as opposed to the simpler icons typically used in a laboratory setting. The study also sought to ascertain the importance of color when considered alongside other visual attributes in the general perception of icons. Participants were then asked to answer preset questions as a means of determining the relationship between the known color properties (e.g., hue, saturation, and brightness) of icons and their functional meaning, effectiveness in conveying meaning, and visual attractiveness. Finally, the speed and accuracy was assessed by which participants recognized well‐known icons rendered using familiar and unfamiliar colors. The empirical results identified color as an important attribute in the process of sorting icons, far exceeding other visual attributes including shape, complexity, pictorial style, and orientation. Nonetheless, it appears that color is not necessarily dominant in the initial stages of sorting. The results also revealed that color is closely related to visual attractiveness but largely irrelevant to effectiveness in the conveyance of meaning. The study also confirmed that correct color information is crucial to naming accuracy and the speed at which icons are recognized. Finally, the results indicate that icons lacking a unique symbol as a cue to recognition rely heavily on their signature color for identification. This study opens up several avenues of research by which to enhance our understanding of the functional role of color in icon perception.     

Effect of poly(styrene-co-maleic anhydride) on physical properties and crystalline behavior of nylon-6/PEBA blends

This study investigated the effect of blending poly(styrene-co-maleic anhydride) (SMA) on the mechanical and thermal properties of nylon-6/polyether block amide (PEBA) blend. In these blends, nylon-6 was toughened with PEBA using SMA as the compatibilizer. All the blends were prepared via direct melt compounding using a co-rotating twin screw extruder. The amount of PEBA added affected the crystallization characteristics and the relative ratio of γ and α crystalline phases of Nylon 6. The crystallization rate of Nylon 6 was also affected by the cooling rate and the amount of PEBA added. The results of mechanical tests showed that the tensile properties, flexural properties, and impact strengths of the nylon-6/PEBA were all increased when blended with 1 wt% of SMA, at both 23 and ?20 °C. However, for neat nylon-6, the impact strength was not affected despite that both tensile and flexural properties were increased by the blending of SMA. The results indicated that SMA can increase the compatibility between nylon-6 and PEBA, thus expanding the usage of nylon-6/PEBA blend in low-temperature applications.     

Compatibilizer effect on Organosilicate reinforced NBR nanocomposites

Nanocomposites of intercalated and exfoliated organosilicates in acrylonitrile butadiene rubber (NBR) were prepared by a two-stage melt blending method. The dispersion and interlayer space of organosilicates in these nanocomposites were examined by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. Dramatic enhancements in the mechanical and thermal properties of NBR were found by incorporating less than ten parts of organosilicates. In particular, the addition of 10 phr of the organosilicate in NBR provided more than a 360% increase in tensile strength, a two-fold increase in M500, a 93% increase in tear strength and a relative enhancement in elongation at break, as compared to the neat NBR. The degradation temperature for NBR with ten parts loading of organosilicate was 25 °C higher than that of the neat NBR. In addition, the relative vapor permeability of nanocomposites containing 15 phr of layered silicates was reduced, as compared to the neat NBR.