Experimental study of the degradation of volatile organic compounds by photocatalytic oxidation using TiO2 pellets

A fixed bed photocatalytic reactor has been designed and built with a UV
radiation source. Ti02 pellets were placed on the three fixed beds within the
reactor. Acetone was used as an indicator of volatile organic compounds (VOCs) during the experiment. Under the flow rate of 12.75 l/min, the oxidation efficiencies were obtained at four different concentrations of acetone laden gas streams ranged from 40ppm to 250ppm. It was found that the lower the acetone concentration of the untreated inlet gas, the higher the oxidation efficiency; the obtained oxidation efficiency was in the range of 40-70% for various concentrations of untreated gases.

Discrimination of origin of farmed trout by means of biometrical parameters, fillet chemical composition and flavour volatile compounds

To date it is well known that the quality of farmed trout is affected by diet composition, by feeding regime, by husbandry practices and by rearing conditions and environment. The trout processing industry and the large-scale retail trade, in consideration of the wide variability of trout quality and characteristics, have imposed, or will soon impose, quality criteria for the end product. Moreover, recent food scares and the malpractices of some food producers have increased public requests
for traceability. The aim of the present study was to evaluate the main chemical quality and the biometrical characteristics of rainbow trout produced in three different farms in Italy (two intensive farms, located one on mountain and one on plain, and an extensive farm in which fish fed only on naturally available nutrients) and to establish whether farmed trout
origins could be differentiated by these parameters. Trout farmed in the intensive mountain farm (IMF) showed the highest crude lipid content in the fillets and the fatty acids of their fillets were characterized by the highest percentage of MUFA. Trout farmed in the intensive plain farm (IPF) were characterized by low dressing percentage, and the lipid of their fillets
was rich in n-6 fatty acids. Trout stocked for the last year of their life in the extensive farm (EF) were leaner both in the carcass and in the fillets. The analysis of flavor volatile compounds showed some differences in the bouquet design, particularly differences in the amounts of n-3 and n-6 derivates volatile aldehydes and alcohols. All data significantly different
(P<0.05) were subjected to Linear Discriminant Analysis (LDA) and 8 variables were chosen to create two discriminant equations generating a strong prediction model for classification of farmed trout respective to their origins.

Effects of dietary lipid sources on flavour volatile compounds of brown trout (Salmo trutta L.) fillet

The high cost and unpredictable availability of fish meal and fish oil (FO) forced feed mill companies to look for alternative ingredients for aquafeeds. In this study, the effects of alternative dietary lipid sources [FO as control, canola oil (CO), oleine oil (OO), poultry fat (PF) and pork lard (PL)] in trout feed on flavour volatile compounds occurring in brown trout (Salmo trutta L.) fillet were evaluated after 70 days of feeding (rearing temperature 14.6°C). Total amounts of volatile compounds identified were higher for fillets of fish fed diets containing only FO as lipid sources. Total amount of alcohols and aldehydes of the fillets were linearly directly related to the percentage content of polyunsaturated fatty acids (PUFA) n-3 of brown trout flesh. The use of alternative dietary lipid sources, modifying the fillet fatty acids composition, affect the total amount of volatile compounds and, changing the relative amount of each volatile compound, affect the flavour of the fish flesh.

Effects of dietary lipid source on fillet chemical composition, flavour volatile compounds and sensory characteristics in the freshwater fish tench (Tinca tinca L.)

In this study the effects of soybean and linseed oils on chemical and sensory characteristics of fillets were evaluated in the freshwater fish tench (Tinca tinca L.). Five experimental diets, differing only in the relative amount of soybean and linseed oil, were formulated and the experiment was conducted on 360 sub-adult tench for 12 weeks. The fatty acid composition of muscle reflected that of the diets and significant correlations were observed. Diets containing higher amounts of n − 6 fatty acids were responsible for an increased level of n − 6 fatty acids in the fish flesh. Consequently, an increase in the relative amount of n − 6-derived volatile aldehydes was also observed. These latter compounds are generally reported to contribute negatively to the general aroma of fish muscle and, consistently, the results of the sensory analysis showed a high value for the “off-flavour” attribute for fish fed the diet containing only n − 6-rich soybean oil.

The cost of storing checkpoints to multiple volatile storage locations using at-least-k semantics

Using the volatile memory of other computers within a system to store checkpoints is an alternative to the traditional approach of using stable storage. The objective of this study is to develop a storage mechanism using at-least-k delivery semantics. This semantics allows data to be saved to a minimum number of computers simultaneously using group communications, without requiring that each group computer successfully acknowledge the receipt. The new storage mechanism is implemented in the GENESIS checkpointing facility v2.0. The results showed that at-least-k storage mechanisms provide low storage latency times; however, the incurred execution overheads on the applications executing within the system are higher than that when using remote stable storage to store checkpoints.

Fatty acid composition and volatile compounds of caviar from farmed white sturgeon (Acipenser transmontanus)

The present study was conducted to characterize caviar obtained from farmed white sturgeons (Acipenser transmontanus) subjected to different dietary treatments. Twenty caviar samples from fish fed two experimental diets containing different dietary lipid sources have been analysed for chemical composition, fatty acids and flavour volatile compounds. Fatty acid make up of caviar was only minimally influenced by dietary fatty acid composition. Irrespective of dietary treatments, palmitic acid (16:0) and oleic acid (OA, 18:1 n-9) were the most abundant fatty acid followed by docosahexaenoic acid (DHA, 22:6 n-3) and eicopentaenoic (EPA, 20:5 n-3).

Thirty-three volatile compounds were isolated using simultaneous distillation–extraction (SDE) and identified by GC–MS. The largest group of volatiles were represented by aldehydes with 20 compounds, representing the 60% of the total volatiles. n-Alkanals, 2-alkenals and 2,4-alkadienals are largely the main responsible for a wide range of flavours in caviar from farmed white surgeon

Direct measurement of surface forces due to charging of solids immersed in a nonpolar liquid

Direct measurements of a long-range force between charged solid surfaces in a nonpolar liquid are presented for the first time. Measurements were made between mica surfaces in solutions of the anionic surfactant sodium di-2-ethylhexylsulfosuccinate (AOT) at millimolar concentrations in n-decane using a surface force apparatus which has been modified to improve its sensitivity for detecting a weak and long-range force. Modifications include a magnetic drive system, the use of a weak cantilever spring with the apparatus mounted in a vertical configuration, and a detailed consideration of the interference optics to allow accurate measurements of surface separations up to several micrometers. The results show a repulsion that is well fitted by theoretical curves based on a model in which only counterions enter the calculation, in other words, in the absence of a reservoir of ions in the solvent. Fitting the theory to the data allows an estimate of the mica surface charge density of ∼1 mC/m². A mechanism for surface charging of mica in this solution is proposed, which includes a role for trace amounts of water that are inevitably present and adsorbed surface aggregates of AOT. The relevance of the results to previously observed charge stabilization of colloids in nonaqueous solvents is discussed.

Measurement of the deformation and adhesion of solids in contact

Two curved surfaces of molecularly smooth mica are brought into contact under a controlled load, and their deformed shape is measured using optical interference fringes of equal chromatic order. This technique allows exceptionally accurate measurements of surface profiles at separations down to a molecular scale. Contact between the surfaces can be made either adhesive or nonadhesive by suitable choice of the medium between them. Results have been obtained in both cases and compared with the theories of Hertz (nonadhesive contact) and Johnson, Kendall, and Roberts (adhesive contact).