Evaluation of volatile compounds and free fatty acids in set types yogurts made of ewes’, goats’ milk and their mixture using two different commercial starter cultures during refrigerated storage

Six different types of yogurt were manufactured from Damascus goat milk, Awassi ewe milk and a mixture of equal portions of the 2 species of milk using 2 types of commercial yogurt cultures (CH-1 and YF-3331). Yogurts were chemically analysed at 1, 7, 14 and 21 days of storage. Results showed that cultures significantly affected acetaldehyde (P < 0.05), acetone (P < 0.05) and diacetyl (P < 0.001) contents. Type of milk significantly influenced acetaldehyde (P < 0.05), diacetyl (P < 0.001), acetoin (P < 0.001) and ethanol (P < 0.05) levels. Significant variations occurred in acetaldehyde (P < 0.001) and acetoin (P < 0.05) contents during the storage. Short-chain free fatty acids were the highest in ewes’ milk yogurt made with culture YF-3331, and increased during storage, while the levels of medium-chain free fatty acids, except for decanoic acid, were unchanged and the amount of long-chain free fatty acids decreased during storage. Cultures used and types of milk had no effect on long-chain free fatty acids in yogurts.     

Effect of surface conditioning methods on the microtensile bond strength of repair composite to indirect restorative materials

This study evaluated the effect of surface conditioning methods on the microtensile bond strength (µTBS) of a restorative composite to indirect restorative materials. Blocks (5?×?5 × 4?mm³) (N?=?72) of (a) Zirconia (In-Ceram Zirconia, Vita) (ZR), (b) lithium disilicate glass ceramic (IPS Empress II, Ivoclar Vivadent) (LD), (c) Indirect resin composite (Gradia, GC) (GR) were fabricated (n?=?24 per group) and divided randomly into three groups: 1-Control: no conditioning, 2-Silane coupling agent, 3-Hydrofluoric acid (9.5%) (HF)+silane. Each block was duplicated in resin composite. The adhesion surfaces were conditioned with airborne-particle abrasion (110?µm Al₂O₃ particles). Half of the conditioned blocks received no bonding and the other half one coat of bonding (ED Primer II, Kuraray). Each conditioned block was bonded to a composite block with a resin luting agent (Panavia F2.0, Kuraray). The blocks were sectioned into 1?mm² microsticks and tested for microtensile bond strength (µTBS) (0.5?mm/min) in a μTBS testing machine. Failure types were evaluated under stereomicroscope and Scanning Electron Microscope (SEM). Data were analyzed using three-way ANOVA, Bonferroni corrected and independent sample t-tests (p?<?0.05). Significant effect of the bonding (p?<?0.001) and surface conditioning (p?<?0.001) were observed in all groups. The highest mean bond strength values were obtained in the bonded, HF etched and silanized groups of ZR, LD and GR (12.4?±?2.9, 28.1?±?1.5 and 27.2?±?2?MPa, respectively). HF acid?+?silane increased the repair bond values in all materials. Majority of the failure types were adhesive for ZR group, whereas HF?+?silane conditioned LD and GR groups presented predominantly cohesive failures in the cement.     

Dynamic changes in salivation,salivary composition,and rumen fermentation associated with duration of high-grain feeding in cows

Salivary secretions are essential for the regulation of digestive processes, as well as rumen and cow health. This research evaluated the effects of the duration of high-grain feeding, and of the time relative to a meal, on salivation, saliva properties, feed bolus characteristics, chewing activity, ruminal and reticular volatile fatty acids, as well as salivary and ruminal pH. Nine nonlactating cannulated Holstein cows were sampled at 1 and 23 d after transition to a 65% grain diet (short term and long term, respectively). Both before and after a controlled meal (2.5 kg of dry matter, offered over 4 h), unstimulated saliva was taken orally for composition analysis. Stimulated salivation and feed boli characteristics were evaluated by collection of ingesta from cardia during 30 min. Chewing and ruminal pH were measured during the controlled meal and for a total of 6 h thereafter. Results from unstimulated saliva showed no effect of the duration of high-grain feeding on bicarbonate, phosphate, total proteins, mucins, lysozyme, and buffer capacity, but increased osmolality at the long term. Lysozyme activity did not differ with high-grain feeding duration, but tended to be lower after the meal. In contrast to short-term-fed cows, the long-term-fed cows increased both meal consumption and feed bolus size, but decreased chewing and feed ensalivation (5.2 vs. 4.6 ± 0.50 g of saliva/g of dry matter), and had lower pH of the stimulated saliva (7.00 vs. 6.67 ± 0.076). These cows also had decreased chewing index (66.5 vs. 45.4 min/kg of neutral detergent fiber), and despite the increase in stimulated saliva buffer capacity (0.027 vs. 0.039 ± 0.006), mean ruminal pH decreased (6.31 vs. 6.11 ± 0.065) during ad libitum feeding. Both in the rumen and reticulum, the concentration of total volatile fatty acids was lower and propionate proportion was higher at the long term. Linear regression analyses revealed a positive influence of the flow rates of salivary bicarbonate and phosphate on ruminal pH during the short term. For every 1-mol increment in the flow of bicarbonate or phosphate, ruminal pH increased by 0.062 or 0.439 units, respectively. Overall, salivary buffers are key determinants of ruminal pH regulation, especially during short-term grain feeding. However, in the long term, ruminal pH drop during ad libitum feeding was stronger, and this effect seems to be exacerbated by increased feed bolus size, accompanied by reductions in feed ensalivation, stimulated saliva pH, and chewing index.     

Characterization of tertiary amine and epoxy functional all-acrylic coating system

For many years the coating industry has been working on developing and/or improving non-isocyanate (NISO) coating systems to meet environmental and safety concerns without sacrificing their performance. The approach of all acrylic (AA) resins, in general comprises of anhydride/hydroxyl, tertiary-amine/epoxy, carboxy/epoxy, or activated hydrogen/ketimine functional groups. The objective of this study is to show that the functional groups in tertiary amine acrylic and epoxy acrylic resins can be determined by means of FTIR and Pyrolyzer GC/FID.     

The Effect of Excess Y<Subscript>2</Subscript>O<Subscript>3</Subscript> Addition on the Mechanical Properties of Melt-Processed YBCO Superconductor

In this study, two kinds of melt-processed YBCO samples with Y₂O₃ addition were fabricated and their microstructures were defined by XRD analysis and polarized light optical microscopy. The mechanical properties of these compounds have been investigated by measuring the Vickers hardness. The superconducting transition temperature was determined by inductive measurements for oxygenated and non-oxygenated samples. The compacted powders were located on a crucible with a buffer layer of Y₂O₃ and a crucible with Y₂O₃ powder freely poured to avoid liquid to spread on the furnace plate. It was found that the sample located on crucible with freely poured Y₂O₃ powder has shown almost single crystal and indicated a very sharp transition curve.     

Lactate detection by colorimetric measurement in real human sweat by microfluidic-based biosensor on flexible substrate

In this study, we describe the colorimetric detection of lactate concentration in real human sweat samples, as an indication of the performance of especially athletes, on a microfluidic device fabricated on a microfibrous nonwoven substrate comprising microfluidic channels and detection reservoirs. A narrow group (10 healthy individuals: 5 women and 5 men) within age range of 20–25 was used. The optimization and real sweat studies demonstrated that color formation on the biosensor surface is influenced not only by the enzyme, ABTS, gelatin ratios but also by many parameters such as storage conditions. Usage of real sweat samples showed that simulated samples only have limited similarity with the real samples and their contents can have a significant impact on the biosensor, in our case on color formation. To understand the response better, larger group of human subjects should be examined in detail in terms of effect of sweat properties to biosensor signal.     

Preparation and electrochemical behavior of dopamine-selective polymeric membrane

Summary o-toluidine was polymerized electrochemically using constant-potential electrolysis at a gold electrode surface. Electrochemical behavior of dopamine and ascorbic acid at the polymer electrode prepared in this manner was examined by cyclic and differential pulse voltammetry techniques. The influence of chemical and electrochemical variables on dopamine selectivity of the polymer electrode was systematically investigated and the optimal values for each parameter were determined. Experimental results showed that optimized polymeric membrane exhibited selectivity for dopamine while blocking ascorbic acid. Therefore, it is claimed that poly (o-toluidine) film can be used as a dopamine-selective polymeric membrane in the presence of ascorbic acid. Key Words: poly (o-toluidine); selective membrane; dopamine Received: 22 November 1999/Revised version: 25 January 2000/Accepted: 10 February 2000     

Energy production from the pyrolysis of waste biomasses

Pyrolysis of waste biomasses was carried out at the temperatures of 450 and 500°C by heating at 5°C min^?1. Products were collected from emitted gases in a nitrogen purge stream; condensable liquids in the gases were collected by condensation. Gaseous, condensed liquid products and residual solids were collected and analyzed. Condensates were extracted with ether to recover the bio oils (BOs). The maximum liquid yield was obtained from the pyrolysis of soybean oil cake (SBOC) at 500°C with a yield of 60% ca. The BO was higher in the case of SBOC than that of sunflower oil cake (SFOC) at the temperatures of 450 and 500°C. With increasing temperature, bio char yield from the pyrolysis of SFOC decreased, while the liquid yield increased. The increase in temperature did not significantly affect the product distribution for the pyrolysis of SBOC. The compositions of BOs were similar for both SBOC and SFOC. Phenols, phenol derivatives including guaiacols and alkyl‐benzenes were the most common and predominant in BOs from both the pyrolysis of SBOC and SFOC. Carbon dioxide was the major gas product for both SBOC and SFOC. Copyright © 2008 John Wiley & Sons, Ltd.     

Thermal and dynamic mechanical properties of γ‐ray‐cured poly(methyl methacrylate) used as a dental‐base material

In this study, γ rays were used for the first time to cure dental‐base material. The effect of the radiation dose on the thermal and rheological properties of poly(methyl methacrylate) (PMMA) used as a dental‐base material was investigated. The commercial powder and liquid material (heat‐curing‐grade) were mixed and polymerized at 60 and 70°C in a constant‐temperature water bath for 30 min and then were cured by γ rays, with total doses of 7.5, 15, 22.5, 30, 45, 52.5, 360, and 2160 krad. For each sample, the viscosity‐average molecular weights were measured, and no significant differences were observed of total dose on molecular weights. A thermal investigation with differential scanning calorimetry showed an exothermic peak in the thermograms of samples that were not completely polymerized and crosslinked. The rheological nature of the samples was studied with dynamic mechanical analysis. A comparison of properties of γ‐ray‐cured samples and those cured by other methods revealed γ curing to be a superior method for producing high‐molecular‐weight homogenous polymers with low porosity and crosslinking. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1291–1296, 2001     

Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250–450 MPa at 20–50 °C for 15–60 min. In the second part, two steps treatments were performed as water blanching at 40–70 °C for 15 and 30 min after pressurization at 250 MPa and 20 °C for 15–60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 °C and then it decreased to 9% at 60 min. When the carrots were water blanched at 50 °C for 30 min after HHP treatment of 250 MPa at 20 °C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanching at 50 °C for 15 min after pressurization at 250 MPa and 20 °C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 °C for 15 or 30 min, water blanching at 60 °C for 30 min provided 2–3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 °C for 30 min provided 70% LOX inactivation in green peas.