Modeling wood fiber deformation caused by vapor expansion during steam explosion of wood     

Muhammad Muzamal  E. Kristofer Gamstedt  Anders Rasmuson 《Wood Science and Technology》2014,48(2):353-372

Steam explosion is a process used to enhance enzyme penetration and digestibility of wood. Wood chips are processed with high-pressure steam for a limited time, and the bonding between polysaccharides and lignin is weakened. After this processing, the pressure is rapidly reduced to induce steam explosion where the vapor inside a fiber expands and exerts pressure on the fiber walls. This pressure causes fiber deformation and breakage. In this study, fiber deformation caused by vapor expansion was simulated by single wood fibers using finite element modeling. When pressure is applied inside a fiber, it is likely to break from the corner and midway between two adjacent corners. The fiber is modeled with four layers (P, S1, S2, and S3). Although the P, S1, and S3 layers are very thin, they significantly prevent fiber deformation. The fibers with a thin wall and a low micro-fibril angle (MFA) deform more than the fibers with a thick wall and a higher MFA. It was found that the shape of the fiber plays an important role in its deformation. The areas of localized strain are the most likely places for fiber splitting. Essentially, fiber wall damage is more likely to occur in (1) thin-walled fibers, i.e., earlywood, (2) fibers with damaged P and S1 layers, (3) fibers with low MFAs, and (4) fibers with irregular cross-sections. Different chemical pretreatments, fractionation procedures, and selections of raw materials can accordingly be considered to produce easily steam-exploded materials.  相似文献   

Innovation diffusion of new wood-based materials – reducing the “time to market”     

Anders Roos  Mikael Lindström  Lena Heuts  Nippe Hylander  Erik Lind  Christian Nielsen 《Scandinavian Journal of Forest Research》2014,29(4):394-401

The purpose of this study is to understand the innovation diffusion of new wood-based materials, “from lab to market,” to identify the success factors and barriers to market introduction, and to reveal important factors for the success of commercialization. Examples are given from target markets in the furniture, appliance, and automotive sectors. This study is based on three qualitative interview studies in Sweden from 2010 to 2012. The analysis showed that the diffusion process of a new bio-based material normally takes up to 10 years or even more. There are only a few companies along the supply chain whose specialized function is finding new materials. However, the automotive industry regularly monitors the development of new materials. Industrial customers of materials generally obtain information about biobased materials from suppliers, exhibitions, conferences, professional contacts, industry magazines, digital media, customers, and partners in development projects. Different industry sectors apply specific material requirements. Regulations regarding safety issues have a high priority, and the interviewees believed that environmental considerations will increase with time. If the materials are equal in other quality dimensions, environmental performance may cast the deciding vote. Recommendations for a faster diffusion cover the right mix of competences, financing, regulations, creativity, and support from the leadership.  相似文献   

Fat or lean? The quantitative genetic basis for selection strategies of muscle and body composition traits in breeding schemes of rainbow trout (Oncorhynchus mykiss)     

Declan Tobin  Esa A. Mäntysaari  Dominic F. Houlihan  Anders Kiessling  Krisna Rungruangsak-Torrissen  Kari Ruohonen 《Aquaculture (Amsterdam, Netherlands)》2006,261(2):510-521

Quantitative genetic analyses of fish composition have been strongly biased towards lipid deposition, rather than protein deposition. This is partly at odds with desires of the modern aquaculture industry, to improve the efficiency of lean growth. Using a quantitative genetic approach, we examined the selection potential in both protein and lipid components of wet weight growth in rainbow trout over a two-year growth period. Two diet treatments were applied to test the hypothesis that an experimental, high protein, low lipid diet (HP) would enhance selection potential compared to the current modern, normal protein, high lipid diet (NP). We found that lipid traits (lipid body weight, percent muscle and body lipid; h² = 0.40) were more heritable than corresponding protein traits (protein body weight, percent muscle and body protein; h² = 0.18), indicating a higher selection potential for lipid traits. The results revealed further that breeding for improved lipid composition over the whole growth period is easier than for protein composition. This was shown by the high favourable genetic correlations between differently aged fish for lipid traits. In contrast, the respective correlations for protein traits were low or even negative. Similarly, the genetic correlations between muscle and body composition were higher for lipid than for protein, enhancing selection efforts to change lipid traits. Heritabilities increased with age, implying that selection practiced on old (> 800 g) rather than young (< 60 g) fish should be more effective in achieving a compositional response. Although the diet had a significant effect on the composition traits, there was no general trend for diet differences in heritabilities of either protein or lipid traits. Thus, the hypothesis of increased selection potential on HP diet was not supported. In conclusion, lipid traits are both more variable and exhibit more favourable genetic architecture for selection compared to protein traits.  相似文献   

饲料质量与污染     

References： 《海洋水产研究》2001,22(4):64-70

Feed quality,the nutritional quality of feed components may affect absorption and digestibility of the feed,and thus the effluent of chemical components from the faeces.In particular,regimen based on high quality feed in aquaculture may reduce effluents and pollution to the surrounding environment.  相似文献   

Interactions between ice storage time, collagen composition, gaping and textural properties in farmed salmon muscle harvested at different times of the year   总被引：1，自引：0，他引：1  

Marit Espe  Kari Ruohonen  Marit Bjrnevik  Livar Fryland  Ragnar Nortvedt  Anders Kiessling 《Aquaculture (Amsterdam, Netherlands)》2004,240(1-4):489-504

Atlantic salmon were sampled in June, September and February of the consecutive year and were stored on ice for up to 14 days in order to test the effect of harvest time and subsequent ice storage on meat quality. Texture and gaping frequency were analysed and were related to colour, protein degradation, collagen solubility, collagen types and final pH as well as lipid oxidation in the fillets to test possible interactions between harvest time and quality degradation during storage. In February, the connective tissue contained more soluble collagen and less insoluble collagen, as well as more of both types I and V collagen, than in the samples collected in June. During ice storage, fish became softer with a concomitant increase in the number of fish displaying very high gaping. pH increased during ice storage and fillet colour became lighter and redder, while yellowness changed in the fattier fillets upon ice storage. Ice storage resulted in changes in pepsin-soluble collagen (PSC) depending on harvest time as did both types I and V collagen. The softer the fish, the higher the gaping score and the more insoluble collagen, the less gaping occurred.  相似文献   

Finite element analysis of tensegrity structures in offshore aquaculture installations     

sten Jensen  Anders Sunde Wroldsen  Pl Furset Lader  Arne Fredheim  Mats Heide 《Aquacultural Engineering》2007,36(3):272-284

Aquaculture is the fastest growing food producing sector in the world. Considerable interest exists in developing open ocean aquaculture in response to a shortage of suitable, sheltered inshore locations and possible husbandry advantages of oceanic sites such as increased water quality and oxygen supply, which improve production efficiency and the quality of fish. The extreme weather conditions experienced offshore leads to a focus on new structure concepts, remote monitoring and a higher degree of automation in order to keep the cost of constructions with an economically viable range. This paper proposes tensegrity structures in the design of wave compliant structures for offshore aquaculture. The objective of this paper is to study several different combinations of pre-stress and stiffness and determine how they influence the stiffness of the tensegrity structure. The finite element analysis program ABAQUS™ has been used to investigate the load carrying capacity of a tensegrity beam structure. The stiffness properties of the tensegrity beam were observed to be highly non-linear and dependent on pre-stress and spring stiffness. When designing a tensegrity beam, both pre-stress and spring stiffness should be considered to ensure the desired structural properties. A large strength to mass ratio and promising properties with respect to control of geometry, stiffness and vibration could make tensegrity an enabling technology for future developments. The suggested concept, the tensegrity beam, shows promising stiffness properties in tension, compression and bending, which are relevant for development of open ocean aquaculture construction for high energy environments.  相似文献   

Opto-electronic counters for postlarvae and juveniles of Macrobrachium rosenbergii (de Man); design and tests of Type B counter     

D.C. West  Rogene K. Thompson 《Aquacultural Engineering》1983,2(3):213-232

The disadvantages of hand counting hatchery produced juveniles of Macrobrachium rosenbergii have been overcome by development of a high speed opto-electronic counter. The hydraulic, mechanical and electronic designs of the Type B counter are described. The counter, extremely fast in principle, is being used and tested under commercial hatchery conditions. Its practical speed of operation and accuracy are expected to exceed 100 000 juveniles per hour and 95%, respectively.About 80% of juveniles show some morphological damage but most of this probably originates in the hatchery rearing tanks. Tests show that slight additional damage is caused only to the antennules of juveniles passing through the counter but this does not affect their subsequent growth rate and survival. It is suggested that density dependent aggression in hatchery tanks is the principal cause of damage. Counter B is shown to be suitable and safe for counting freshwater prawn juveniles. This counter could be adapted to count other macroscopic aquatic organisms via suitable dimensional scaling. No other counters of this type and purpose appear to exist.  相似文献   

Hyper dense vertebrae and mineral content in Atlantic salmon(Salmo salar L.) fed diets with graded levels of phytic acid     

Synnøve Helland  Vegard Denstadli  Kirsti Hjelde  Anders Skrede  Grete Baeverfjord 《Aquaculture (Amsterdam, Netherlands)》2006,261(2):603-614

The effects of graded levels of phytic acid on skeletal development and mineral deposition were investigated in an 80 day feeding trial with Atlantic salmon (Salmo salar L.) parr. The level of phytic acid had no significant effect on the phosphorus (P) content of either whole body or vertebral column of Atlantic salmon. Negative effects of high phytic acid levels were, however, found on whole body concentration of calcium (Ca), magnesium (Mg), and in the Ca:P ratio, and in the vertebral column concentration of zinc (Zn). A novel type of vertebral pathology was observed, hyper dense (HD) vertebrae. The HD vertebrae appeared denser on radiographic images, and they consisted of a denser trabecular network than the surrounding vertebrae. The number of fish with HD vertebrae increased from initially 16% to 45-60%, with a tendency of more fish with HD vertebrae with increasing dietary phytic acid content. The HD vertebrae are described and illustrated with radiographic images, whole mount staining, and histology.  相似文献   

Effect of sustained exercise on white muscle structure and flesh quality in farmed cod (Gadus morhua L.)     

Marit Bjørnevik  Ørjan Karlsen  Ian A Johnston  & Anders Kiessling 《Aquaculture Research》2003,34(1):55-64

Growth performance and white muscle cellularity were investigated in Atlantic cod (Gadus morhua L.) (500–600 g) to determine if texture and thereby quality is affected by exercise. Three exercise regimes [low flow, 0.5 body lengths per second (BL s^?1) and 1.0 BLs^?1] were applied, and the experiment was run for 9 months, at which point the fish had reached around 2 kg body weight. There were no significant differences in fork length or condition factors between groups that could be attributed to the exercise treatment, but the 0.5 BL s^?1 group had significantly lower body weight performance than the control group. The average specific growth rate ranged from 0.37% to 0.42% per day. Muscle fibre diameter was positively correlated with fish weight. However, there was no difference in the distribution of muscle fibre diameters between treatment groups. A texture analyser, model TA‐XT2, equipped with a Warner–Bratzler shear blade was used to measure the texture of the fillet. No correlation was found between the shear force required to cut through the sample and the muscle fibre diameter, but the shear force decreased with increasing growth rate. A tristimulus colorimeter was used to measure the colour composition of the fillet instrumentally. Red/green chromaticity (a*) was positively correlated with the shear force. It was concluded that the exercise regimes tested were insufficient to influence either growth performance or muscle growth patterns. Individual variations in fibre diameter did not influence the colour or texture of the fillet.  相似文献   

Stochastic simulation modeling to determine time to detect Bovine Viral Diarrhea antibodies in bulk tank milk     

Alessandro Foddai  Claes Enøe  Kaspar Krogh  Anders Stockmarr  Tariq Halasa 《Preventive veterinary medicine》2014

A stochastic simulation model was developed to estimate the time from introduction of Bovine Viral Diarrhea Virus (BVDV) in a herd to detection of antibodies in bulk tank milk (BTM) samples using three ELISAs. We assumed that antibodies could be detected, after a fixed threshold prevalence of seroconverted milking cows was reached in the herd. Different thresholds were set for each ELISA, according to previous studies. For each test, antibody detection was simulated in small (70 cows), medium (150 cows) and large (320 cows) herds. The assays included were: (1) the Danish blocking ELISA, (2) the SVANOVIR^®BVDV-Ab ELISA, and (3) the ELISA BVD/MD p80 Institute Pourquier. The validation of the model was mainly carried out by comparing the predicted incidence of persistently infected (PI) calves and the predicted detection time, with records from a BVD infected herd. Results showed that the SVANOVIR, which was the most efficient ELISA, could detect antibodies in the BTM of a large herd 280 days (95% prediction interval: 218; 568) after a transiently infected (TI) milking cow has been introduced into the herd. The estimated time to detection after introduction of one PI calf was 111 days (44; 605). With SVANOVIR ELISA the incidence of PIs and dead born calves could be limited and the impact of the disease on the animal welfare and income of farmers (before detection) could be minimized. The results from the simulation modeling can be used to improve the current Danish BVD surveillance program in detecting early infected herds.  相似文献