Influence of surface-modified TiO nanoparticles on fracture behavior of injection molded polypropylene

We prepared surface-modified TiO₂ nanoparticle (21 nm)/polypropylene nanocomposites using a twin-screw extruder and an injection molding machine. The TEM (transmission electron microscopy) and SEM (scanning electron microscopy) images showed homogeneous dispersion of nano-TiO₂ at 1 vol.% filler content and weak nanoparticle matrix interfacial adhesion. It was found that the essential work of fracture (EWF) approach, usually characterizing fracture toughness of ductile materials, was no longer applicable to the nanocomposite samples because of the extreme crack blunting and tearing processes observed in the EWF tests. As an alternative approach, the specific essential work-related yield was used for assessment of the plane-strain toughness, as suggested in the literature. The results indicated that the addition of 1 vol.% nano-TiO₂ did not toughen the polypropylene (PP) matrix at all. On the other hand, it was observed from the EWF tensile curves that the nanoparticles enhanced the ductility of the PP matrix greatly, the reason of which was probably ascribed to the high level of molecular orientation of the injection molded samples, as revealed by the polarized optical microscopy (POM). Because of the highly ductile behavior induced by the nanoparticles, the fracture energy achieved two- to three-fold increase, depending on the ligament lengths of the samples. The difference between the toughness and ductility of nanocomposites was discussed.     

Study of MEH–PPV/PCBM active layer morphology and its application for hybrid solar cell performance

Surface morphologies of MEH?CPPV:PCBM active layers were optimized by investigating ITO substrate treated with oxygen and nitrogen plasma. This treatment effectively improved smoothness, transmittance, and contact angle of ITO??s, resulting in good anode contacts for hybrid device structures. The consistently improved performance of hybrid solar cells was also achieved. The surface properties of treated and untreated ITO substrates were compared by contact angle, four point probe, scanning electron microscopy, and atomic force microscopy.     

MAJOR VOLATILES IN TOASTED CANOLA OIL

Headspace volatiles from 'Alto' canola oil toasted at 240C for 8 min were collected using Tenax ^R TA 60/80 (Supelco Inc., Bellefonte, PA). The Tenax ^R was washed three times with a total of 6 ml of solvent. The solvent extract was concentrated by drying in a hood at room temperature for 6 h. Two μl of concentrated extract were separated on a 30 m DB-1 capillary column (J & W Scientific, Folson, CA) with a Hewlett Packard (HP) 5890A gas chromatograph connected to a HP 5790 mass spectrometer. Volatiles were tentatively identified with a NBS 43 K.1 library by PBM (probability based on matching) search.
Fifty seven peaks were detected by the mass spectrometer. Among those, 50 compounds were tentatively identified. 2-Furancarboxaldehyde, 5-methyl-2-furan carboxaldehyde, 5-(1-methyl ethyl)-1,3-cyclopentadiene, cyclododecane, undecanoic acid, tetradecanoic acid, 1-hexadecanol, hexadecanoic acid, 9-octadecenoic acid, octadecanoic acid, 2,5-dimethyl pyrazine, 3-ethyl-2,5-dimethyl pyrazine, [1,1':3',1"-terphenyl]-1'-ol and [1,1':3',1"-terphenyl]-4'-ol were the major volatile compounds.     

QUALITY OF FROZEN SHRIMP THAWED BY RECIRCULATING AIR VERSUS WATER IMMERSION

The quality of shrimp thawed using a constant temperature thawing chamber compared with running water was studied. Shrimp thawed in room temperature air was used as the control. Shrimp thawed using the thawing chamber had lower drip loss, higher yield and moisture content than shrimp thawed by running water. However, the differences were not statistically significant. There were also no significant differences in press juice and shear force between control and shrimp thawed using either thawing method. Shrimp thawed using the thawing chamber had lower aerobic bacterial counts than either control or shrimp thawed using running water. Shrimp thawed using the thawing chamber did not exceed ?1C throughout the thawing experiment, and microbial growth during thawing was also avoided. Results indicated that the thawing chamber has potential for the foodservice industry to produce uniformly thawed products under sanitary conditions.     

Time-Temperature Indicator using Phospholipid-Phospholipase System and Application to Storage of Frozen Pork

A novel time-temperature indicator (TTI) using phospholipid-phospholipase was developed to monitor quality change of frozen foods during storage. The ITI was more reliable than the lipase system and monitored quality changes of frozen pork during storage. The TTI was designed for reactions at sub-zero temperatures because the substrate emulsion would be stable at such temperatures. The TTI contained glycerol and sorbitol as anti-freeze reagents and was designed to show distinctive color changes according to pH by mixing bromothymol blue, neutral red, and methyl red. The TTI had an activation energy of 32.12 kcal/mol, suitable for many food reactions.     

CHARACTERISTICS OF SARCOPLASMIC PROTEINS AND THEIR INTERACTION WITH MYOFIBRILLAR PROTEINS

The protein solubility and molecular‐weight distribution of freeze‐dried sarcoplasmic proteins (SPs) from rockfish treated under low and high pH as well as various NaCl concentrations were elucidated. The solubility of SPs was significantly suppressed at an acidic pH (2.0–4.0) and in the presence of high salt concentration (0.5 M NaCl). The least amount of protein was lost when SPs were treated at pH 2.0 or 3.0 followed by precipitation at pH 5.5. The interaction of SPs with Alaska pollock surimi (myofibrillar proteins) was also investigated. The addition of SPs appeared to delay the thermal denaturation of myosin and actin. The SPs positively contributed to the gelation of myofibrillar proteins as judged by breaking force.     

HPLC Determination of C-7 Oxidized Cholesterol Derivatives in Foods

A method was developed for the rapid, accurate analysis of C-7 oxdized cholesterol derivatives (C-7 OCDs) in muscle and other foods. The method avoids saponification. Total lipid extracts were fractionated on silica gel columns to concentrate trace sterol oxides from triglycerides, cholesterol, and phospholipids. Sterol oxides in eluates were quantified by normal-phase high performance liquid chromatography. Recoveries of C-7 OCDs added to beef approached 100%. Pancake mix, French fries, and organ product “concentrates” sold in health food stores contained from 1 to 70 ppm of C-7 OCDs (7-keto, 7α-hydroxy and 7β-hydroxycholesterol), but none could be detected in raw beef, fried chicken, cooked hamburger, beef jerky or liver sausage.