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Peer Reviewed
See detailContribution to the study of the allosteric properties of acetylcholinesterase
Gridelet, J.; Foidart, Jean-Michel ULg; Wins, P.

in Archives Internationales de Physiologie et de Biochimie (1970), 78

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See detailContribution to the study of the effect of drying on the nutritive value of corn grain (Zea mays L.) for poultry and pigs feeding
Odjo, Djosse Psijus Sylvanus ULg

Doctoral thesis (2016)

Corn grain (Zea mays L.) is widely produced all over the world and is intensively used in poultry and pigs feeding. Drying with hot air is usually utilized to preserve corn after harvest by decreasing the ... [more ▼]

Corn grain (Zea mays L.) is widely produced all over the world and is intensively used in poultry and pigs feeding. Drying with hot air is usually utilized to preserve corn after harvest by decreasing the water content. During high temperature drying, major components (starch and proteins) of corn grain undergo some structural changes with possible nutritional implication. This thesis aimed at increasing knowledge regarding the effect of the drying process on the feeding value of the corn grain for broilers and pigs feeding. After the general introduction and a review which attempts to summarize the major findings of previous studies carried out on the effects of drying on the nutritive value of corn for broilers feeding, the first in vitro experiment performed aimed to assess the effect of fluidized-bed drying on the digestibility of dry matter, starch and protein using a sequential pepsin-pancreatin protocol. It appeared that when corn grains harvested at similar moisture content are dried at different temperatures, the digestibility of starch and that of crude proteins are not affected in a similar way. Higher drying temperatures increased the final digestibility of starch while the digestibility of crude proteins decreased mainly during the pepsin step of digestion. Differences in the kinetics of starch digestion according to the corn grain temperature were attributed to the structural modifications induced within starch granules and proteins in response to the drying conditions. As the digestion of starch involves the breakdown of glycosidic bonds and results in the production of various oligosaccharides, a second experiment was performed in order to get more insight into the nature of saccharides released after the in vitro digestion of corn grains. Three methods were thus compared in their ability to provide relevant information about sugar saccharides released during an in vitro digestion procedure that mimics the pig digestive model. High Performance Anion Exchange Chromatography coupled with a Pulsed Amperometric Detector was revealed to give the most effective qualitative and quantitative information regarding the digestion of starch. Five major saccharides were found as the result of in vitro pepsin-pancreatin digestion of corn grain: glucose, isomaltose, maltose, maltotriose and glucosyl-maltotriose. The relative concentration of these saccharides varied according to the temperature applied during the corn drying, suggesting that structural changes occurring within starch granules (partial gelatinization) would lead to different digestion profiles in the small intestine and may therefore affect the nutritional physiology in pig intestinal tract. Protein is also affected by the high drying temperature. Among corn protein subgroups, salt-soluble proteins are the most sensitive to heat and their solubility decreases when the drying temperature increases. In a third experiment, the denaturation of salt-soluble proteins during corn drying and hydrothermal treatment was monitored and modelled. The impairment of corn protein solubility in saline buffer was revealed to depend mainly on temperature, time of processing and moisture content of materials treated. The evolution of extractible salt-soluble proteins content of corn kernels during drying at high temperature was more correctly described using the second order kinetic reaction than with the first order kinetic reaction when classical kinetic models were compared. In a forth study the relationship between the in vitro digestibility of dry matter and the salt-soluble protein index was assessed. It was found that the use of salt-soluble protein index as an indicator of the may lead to doubtful conclusion due to confounding factors (temperature and moisture content). Although this study has achieved some progress in understanding the possible link between corn drying parameters and their effects on the performance of poultry and pigs feeding using corn-based diets, as well as on methodologies that may be used to assess the nutritive value of dried corn grains, complementary studies aiming to determine the effectiveness of these effects on livestock and pigs have to be done. [less ▲]

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Peer Reviewed
See detailContribution to the study of the flora and the ecology of cave blue-green algae.
Garbacki, Nancy ULg; Hoffmann, Lucien

Conference (1995)

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See detailContribution to the study of the lipase of Yarrowia lipolytica
Destain, Jacqueline ULg; Roblain, D.; Thonart, Philippe ULg

Poster (1993, June)

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See detailContribution to the study of the mineral hypothesis in relation to the Kashin-Beck disease in Tibet Autonomous Region
DERMIENCE, Michael ULg

Doctoral thesis (2016)

A little known disease called Kashin-Beck disease (KBD) plagues the poor and rural populations in the Tibet Autonomous Region (T.A.R.) and in other provinces of the People’s Republic of China. It is an ... [more ▼]

A little known disease called Kashin-Beck disease (KBD) plagues the poor and rural populations in the Tibet Autonomous Region (T.A.R.) and in other provinces of the People’s Republic of China. It is an endemic and chronic osteochondropathy affecting long bones and joints, sometimes as soon as of the early childhood. Although the etiology of this disease is not clearly established, little doubt remains as to the implication of multiple environmental factors. Intoxication by mycotoxins in cereals and by organic acids in water, deficiencies in selenium and iodine, are all factors having a place in the multifactorial etiology hypothesized. In T.A.R., diet, notably, differentiates the rural community, affected by KBD, from the other communities (nomads and city-dwellers), who remain unaffected. Because more than one chemical element is essential to a healthy bone metabolism, and because there is scarce data, if not any, on the topic, this thesis had to primary objective to investigate the mineral and trace element dietary status of young Tibetan children living in areas endemic for KBD. The first logical action step led us to determine which elements are involved in bone and joints metabolism through an exhaustive review of the scientific literature. Thirty elements were highlighted, and a dozen was deemed relevant in this context. An exploratory study on the Tibetan food composition concluded on a high risk of introducing important bias by using the existing food composition tables for nutritional assessment in T.A.R. Being inescapable tools, a specific food composition table was elaborated for our area of investigation with the close collaboration of the China National Center for Food Safety Risk Assessment (CFSA). During a scientific internship of 7 month in the CFSA, 19 chemical elements were analyzed in not less than 1119 samples of sixteen traditional foods and beverages of rural T.A.R. In order to assess the nutritional status of the children, a cross-sectional study was implemented. 250 preschool children aged 3 to 5 years old from three rural counties around Lhasa were enrolled. They were interviewed twice, at six month of interval, via the 24-hour recall method. The results suggest several imbalances in their dietary mineral intakes compared to the Chinese recommendations. Sodium and manganese intakes are too high, while they are too low for potassium, calcium, zinc, copper and selenium. The Tibetan diet is rich in fiber and in phytic acid, which are susceptible to decrease the bioavailability and to aggravate the deficiencies of the later elements. For this reason, we conducted an animal experimentation on a rat model to assess the apparent digestibility, the fecal excretion and the urinary excretion of minerals and trace elements in the traditional Tibetan dish called tsampa pag. This traditional dish consisting of roasted barley flour mixed with yak butter tea is the mainstay of the Tibetan diet. The results of this experiment suggest low bone mineral density, a possible secondary copper deficiency, and a possible manganese excess in rats that consumed tsampa pag. In view of the results presented, it would be interesting to compare the mineral intake between children living in endemic areas and in non-endemic areas. It would also be interesting to include more of elements known to affect bone metabolism in future studies. [less ▲]

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See detailContribution to the study of the relations between fish of the family of Carapidae and their holothurian hosts
Parmentier, Eric ULg

in SPC Bêche de mer, Information Bulletin (2004), 19

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Peer Reviewed
See detailContribution to the study of the resistance to drying of Pseudomonas fluorescens
Mputu Kanyinda, Jean-Noël ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013)

The objective of this thesis is to study the resistance to drying of Pseudomonas fluorescens. Freeze-drying is the most suitable method for drying P. fluorescens. However, freeze-drying induced loss of ... [more ▼]

The objective of this thesis is to study the resistance to drying of Pseudomonas fluorescens. Freeze-drying is the most suitable method for drying P. fluorescens. However, freeze-drying induced loss of cell viability. This loss of viability is mainly due to membrane rupture, temperature and oxidation of fatty acids, membrane proteins and glutathione. For this purpose, the use of protective compounds during freeze-drying has allowed us to obtain a powder having a high viability. We then studied the impact of these protective compounds, oxygen and storage temperature on the viability of P. fluorescens during storage. Analyses of fatty acids, proteins, glutathione and the study of membrane integrity during the various manufacturing processes and storage have established a link between the degree of oxidation and cell death. The results of flow cytometry showed that the freeze-drying longer affects the viability of P. fluorescens rather than storage. We have increased the yield of the production in bioreactor of P. fluorescens and time of culture was halved. [less ▲]

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See detailContribution to the study of waste heat recovery systems on commercial truck diesel engines.
Espinosa, Nicolas ULg

Doctoral thesis (2011)

Fuel price increase as well as future fuel consumption regulations lead truck manufacturers to further enhance the current powertrain. In such a context, two waste heat recovery technologies appear as ... [more ▼]

Fuel price increase as well as future fuel consumption regulations lead truck manufacturers to further enhance the current powertrain. In such a context, two waste heat recovery technologies appear as promising: the Rankine system as well as the thermoelectric generator. Both technologies are well studied within the past 30 years literature. After a reminding of truck boundary conditions, this thesis work defines a 0-D modeling done under the engineering equation solver for both systems (approaches enabling to define the working fluid for the Rankine system). Then, for both systems a commercial tool is used to further investigate the two technologies. For the thermoelectric generator this commercial tool, developed under Matlab, models a thermoelectric generator architecture (designed for mass production) developed in the frame of a research program. Parametric studies are done on the integration of a thermoelecric generator upstream the existing engine exhaust gas recirculation cooler. Main studies are done with $Mg_2Si$ and $MnSi$ as thermoelectric materials but other materials are also considered. A Rankine system design is presented and modeled under a well known commercial 1-D solver used within the automotive industry. Preliminary validations of the model based on supplier modeling data are presented as well as the modeling validation of the turbine component tested. Transient aspects are evaluated to better understand the behavior of the system and its bottlenecks. The amount of refrigerant in the circuit and the control schematic are also addressed. From these study, it appears that the thermoelectric generator technology is not yet mature for an integration into a long haul truck due too the low performance of thermoelectric materials. The Rankine system technology should handle a complete truck prototype testing to estimate its potential. [less ▲]

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See detailA contribution to the study of β Canis Majoris.
Struve, Otto; Swings, Polydore ULg

in Astrophysical Journal (1941), 94

Coudé spectrograms obtained at the McDonald Observatory on January 22 and 24, 1941, show a velocity range of about 9 km/sec, in a period of 6 hours. The lines are diffuse and shallow near minimum velocity ... [more ▼]

Coudé spectrograms obtained at the McDonald Observatory on January 22 and 24, 1941, show a velocity range of about 9 km/sec, in a period of 6 hours. The lines are diffuse and shallow near minimum velocity and sharper and deeper near maximum velocity. The Ca II line K shares in the oscillations. It is probably a blend of a stellar and an interstellar line. The lines suggest turbulence of an appreciable amount. A line at λ 4469.71 is probably a blend of O II and forbidden He I. A comparison with β Cephei shows that β Canis Majoris is more luminous. It is, however, not a supergiant. The similarity in the periods suggests similarity of internal structure. [less ▲]

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See detailContribution to the study on sound production in clownfishes (Perciformes, Pomacentridae): a multidisciplinary approach
Colleye, Orphal ULg

Doctoral thesis (2011)

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live ... [more ▼]

Clownfishes (Amphiprion spp.) are brightly colored fishes that are members of the Pomacentridae family. They are well known for their mutualistic relationship with tropical sea anemones. These fishes live in social groups in which there is a size-based dominance hierarchy. In this structure where sex is socially controlled, agonistic interactions are numerous and serve to maintain size differences between individuals adjacent in rank. Several studies have reported that vocalizations are associated with agonistic interactions but precise data are lacking and further investigations are needed. The nature of the sound-producing mechanisms also remained unresolved, only resting on few assumptions. Thereby, the main aim of the present thesis is (1) to determine the fundamental components of the acoustic communication in clownfishes, and (2) to explain the mechanisms of sound production. In order to achieve these objectives, the research has been divided into three different axes. Firstly, the study of the acoustic behaviors shows that no acoustic signal is associated with reproductive activities in clownfishes. Sound recordings during agonistic interactions indicate that these fishes produce two types of sounds. Aggressive sounds are produced during chases and threat displays while submissive (or head shaking) sounds are emitted in reaction to aggressive acts by dominant. Both types of sounds show size-related intraspecific differences in dominant frequency and pulse duration: smaller individuals produce higher frequency and shorter duration pulses than larger individuals, and inversely. Consequently, these sonic features might be useful cues for individual recognition and maintenance of cohesion within the group. Secondly, the study of the sound-producing mechanism highlights that aggressive sounds are initiated by buccal jaw teeth snapping caused by rapid mouth closure attributed to a sonic ligament. It appears that the swimbladder does not function as a resonator that amplifies and changes the quality of sounds. This structure is a highly damped sound source prevented from prolonged resonant vibrations. On the other hand, the rib cage might be the major acoustic radiator and its resonant properties might explain the size-related variations observed in pulse duration and dominant frequency. Thirdly, the comparison of aggressive sounds among fourteen clownfish species indicates that the same relationship between fish size and both dominant frequency and pulse duration is spread over the entire group (i.e. tribe Amphiprionini). These results highlight all species use a highly conservative mechanism of vocalization. Pulse period appears to be the most variable acoustic feature and could be involved in species-specific recognition, as well as pulse duration and dominant frequency in a lesser extent through their relationship with body size. Although sound production appears to be restricted to some agonistic behaviors, these sounds seem to constitute an integral part of the peculiar way of life of clownfishes. The aggressive and submissive sounds would also result from two different mechanisms.   [less ▲]

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Peer Reviewed
See detailContribution to the valorisation of pomegranate (Punica granatum L.)
Bchir, Brahim ULg; Roiseux, Olivier; Attia, Hamadi et al

Poster (2007, October 11)

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See detailContribution to the valorization of^pomegranate (Punica granatum L.)
Bchir, Brahim; Roiseux, Olivier; Attia, Hamadi et al

Poster (2007, October 11)

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Peer Reviewed
See detailContribution to the water disinfection study by photosensitization with plants extracts.
Sunda, M.; Rosillon, Françis ULg; Taba, K. M.

in European Journal of Water Quality = Journal Européen d’Hydrologie (2008), 39(2), 199-209

Solar water disinfection study using plants extracts, in tryptophan media (1%), has revealed a photodynamic activity of Cassia alata, Cassia occidentalis, Carica papaya, Phyllantus niruri and Coleus ... [more ▼]

Solar water disinfection study using plants extracts, in tryptophan media (1%), has revealed a photodynamic activity of Cassia alata, Cassia occidentalis, Carica papaya, Phyllantus niruri and Coleus kilimandschari aqueous extracts. Aqueous extracts of Lantana camara, Cymbopogon citratus and Hibiscus rosa-sinensis produce a bactericidal effect. Water disinfection by alkaloid extracts of Cassia alata, Cassia occidentalis, Carica papaya, Phyllantus niruri and Coleus kilimandschari shows a bactericidal effect. On the other hand, unalkaloid extracts of the same compounds especially present a photodynamic activity. The photodynamic activity of unalkaloid extract is due to the presence of quinones and anthraquinones which generate singlet oxygen.The singlet oxygen generated attacks and damages the microorganisms contained in polluted water. The necessary sunlight time for coliform inactivation and other germs is one hour for 2 ml of extracts/liter of polluted water. [less ▲]

Detailed reference viewed: 284 (14 ULg)
See detailcontribution to understanding of sedimentological and diagenetic processus related to a major emersive surface : example of the middle paleocene unconformity (MPU).
Loisy, Corinne; Kiefer-Ollier, Eloise; Cerepi, Adrian et al

in Book of Abstracts - 26th IAS meeting, Alghero, Sardenia (2009)

Detailed reference viewed: 54 (2 ULg)
See detailContribution to understanding of sedimentological and diagenetic processus related to major emersive surfaces and their spatial variation
Loisy, Corinne; Da Silva, Anne-Christine ULg; Kieffer, Eloise et al

in Book of Abstracts - 25th meeting of the IAS, Patras, Greece (2007)

Detailed reference viewed: 16 (1 ULg)