Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailEffect of head-to-head addition in vinyl acetate controlled radical polymerization: why is Co(acac)2-mediated polymerization so much better?
Morin, Aurélie N.; Detrembleur, Christophe ULg; Jérôme, Christine ULg et al

in Macromolecules (2013), 46(11), 4303-4312

The controlled polymerization of vinyl acetate has been recently achieved by several techniques, but PVAc with targeted Mn and low dispersity up to very high monomer conversions and high degrees of ... [more ▼]

The controlled polymerization of vinyl acetate has been recently achieved by several techniques, but PVAc with targeted Mn and low dispersity up to very high monomer conversions and high degrees of polymerization was only obtained with Co(acac)2 as controlling agent in the so-called CMRP, a type of organometallic mediated radical polymerization (OMRP). Other techniques (including ATRP, ITP, TERP, and RAFT/MADIX) have shown a more or less pronounced slowdown in the polymerization kinetics, which was attributed to the higher strength of the C−X bond between the radical PVAc chain and the trapping agent (X) in the dormant species and to a consequent slower reactivation after a less frequent head-to-head monomer addition. The reason for the CMRP exception is clarified by the present contribution. First, a detailed investigation by 1H, 13C and multiplicity-edited HSQC and DEPT-135 NMR of the PVAc obtained by CMRP, in comparison with a regular polymer made by free radical polymerization under the same conditions, has revealed that Co(acac)2 does not significantly alter the fraction of head-to-head sequences in the polymer backbone and that there is no accumulation of Co(acac)2-capped chains with a head-to-head ω end. Hence, both dormant chains (following the head-to-head and the head-to-tail monomer additions) must be reactivated at similar rates. A DFT study shows that this is possible because the dormant chains are stabilized not only by the C−Co σ bond but also by formation of a chelate ring through coordination of the ω monomer carbonyl group. The head-to-head dormant chain contains an inherently stronger C−Co bond but forms a weaker 6-membered chelate ring, whereas the weaker C−Co bond in the head-to-tail dormant chain is compensated by a stronger 5-membered chelate ring. Combination of the two effects leads to similar activation enthalpies, as verified by DFT calculations using a variety of local, gradient-corrected, hybrid and “ad hoc” functionals (BPW91, B3PW91, BPW91*, M06 and M06L). While the BDE(C−X) of model H-VAc−X molecules [X = Cl, I, MeTe, EtOC(S)S and Co(acac)2] are functional dependent, the BDE difference between head-to-head and head-to-tail dormant chain models is almost functional insensitive, with values of 5−9 kcal/mol for the ATRP, ITP and TERP models, 3−6 for the RAFT/MADIX model, and around zero for CMRP. [less ▲]

Detailed reference viewed: 27 (8 ULg)
Full Text
Peer Reviewed
See detailThe effect of health related quality of life on reported use of health care resources in patients with osteoarthritis and rheumatoid arthritis: a longitudinal analysis.
Ethgen, Olivier ULg; Kahler, Kristijan H; Kong, Sheldon X et al

in Journal of Rheumatology (2002), 29(6), 1147-55

OBJECTIVE: In today's cost conscious environment, health services researchers are consistently trying to find ways to predict future health care resource utilization (HCRU) and its associated costs. We ... [more ▼]

OBJECTIVE: In today's cost conscious environment, health services researchers are consistently trying to find ways to predict future health care resource utilization (HCRU) and its associated costs. We evaluated the impact of health related quality of life (HRQL) on future HCRU in patients with arthritis. METHODS: A total of 642 patients with rheumatoid arthritis (RA) and 395 patients with osteoarthritis (OA) completed at least 2 and as many as 6 consecutive surveys at 6 mo intervals. Information collected included demographics, HRQL questionnaires [Medical Outcome Study Short Form 36 (SF-36), Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), and the Stanford Health Assessment Questionnaire (HAQ)], and HCRU over the previous 6 months. Longitudinal data analysis was perfomed to assess the effect of HRQL on future HCRU. RESULTS: Statistically significant associations between HCRU and HRQL variables were noted. Higher rates of HCRU were found in those in the worst quarter compared with those in the best quarter of HRQL. With the HAQ, OA and RA patients in the worst quarter reported a 199% (p < 0.05) and 48% (p < 0.05) increase in rheumatologist visits, respectively. With the WOMAC Function, increases were as high as 196% (p < 0.05) in rheumatologist visits for patients with OA. Patients with RA with a high level of HRQL as measured by the SF-36 (physical component score) reported a decrease of 31% (p < 0.01) in general practitioner visits and a decrease of 52% (p < 0.01) in hospitalization (mental component score). CONCLUSION: These findings suggest that HRQL may be used to predict future health care consumption. Such an approach may lead to a more efficient allocation of resources by providing useful information to health care providers and health care decision makers. [less ▲]

Detailed reference viewed: 8 (3 ULg)
Full Text
Peer Reviewed
See detailEffect of heart failure on dipeptidyl peptidase IV activity in plasma of dogs.
Gomez, N.; Matheeussen, V.; Damoiseaux, Cécile ULg et al

in Journal of Veterinary Internal Medicine (2012)

Detailed reference viewed: 25 (4 ULg)
Full Text
Peer Reviewed
See detailThe effect of heat stress on freeze-drying and conservation of Lactococcus
Ziadi, M.; Touhami, Y.; Achour, M. et al

in Biochemical Engineering Journal (2005), 24(2), 141-145

The production of lactic acid bacteria isolated from Tunisian fermented milk (Lben): Lactococcus lactis subsp. lactis var. diacetylactis (SLT6) was investigated in fed-batch process. The final biomass ... [more ▼]

The production of lactic acid bacteria isolated from Tunisian fermented milk (Lben): Lactococcus lactis subsp. lactis var. diacetylactis (SLT6) was investigated in fed-batch process. The final biomass production was 2.2710(11) cfu/ml. The effect of heat stress, after fermentation, on the survival rate after freeze-drying and during storage was studied. The survival rate after freeze-drying of SLT6 subject of a thermal treatment was 38.8% whereas it was only 21.9% for unprocessed SLT6. The accelerated shelf life testing (ASLT) method was used to study the effect of heat stress on conservation of Lactococcus. The bacterium was stored at four different temperatures of 4, 15, 25 and 37 degrees C. Lactococcus cell kinetic behaviour suggested a first order reaction, and the effect of storage temperature was quantified by determination of the half-life period and the activation energy. The beneficial effect of heat stress is clearly associated with a half-life period of 86 days for SLT6T and only 48 days four SLT6NT stored at 4 degrees C. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 63 (3 ULg)
Full Text
Peer Reviewed
See detailEffect of heat treatment of rennet skim milk induced coagulation on the rheological properties and molecular structure determined by synchronous fluorescence spectroscopy and turbiscan
Blecker, Christophe ULg; Habib-Jiwan, Jean-Michel; Karoui, Ramdhane

in Food Chemistry (2012), 135(3), 1809-1817

Heat treatment applied to milk induces denaturation of whey proteins, leading to a complex mixture of whey protein and whey protein coated casein micelles. The present paper investigates the effects of ... [more ▼]

Heat treatment applied to milk induces denaturation of whey proteins, leading to a complex mixture of whey protein and whey protein coated casein micelles. The present paper investigates the effects of heat treatment (60 and 80 °C during 20 min) and rennet-induced coagulation temperature (30 and 40 °C) determined by rheology, synchronous fluorescence spectroscopy (SFS) and turbiscan measurements. The gelation times determined by rheology and SFS increased with the increase of heat treatment applied to milk. The rise in temperature induced a decrease in the maximum curd firming rate and an increase in the viscosity of the investigated milk samples. The principal component analysis (PCA) applied, sepa- rately, to the SF and turbiscan spectra showed a clear discrimination between: (i) raw milks and heated milks; and (ii) milks renneted at 30 °C from those renneted at 40 °C. The results showed the ability of SFS as a rapid and non-destructive technique for the: (i) monitoring network structure and molecular inter- action during the coagulation process; and (ii) determination of gelation time of rennet-induced coagu- lation of studied milk samples. [less ▲]

Detailed reference viewed: 10 (1 ULg)
See detailEffect of hemicellulase preparations on performance parameters, intestinal viscosity and apparent nutrient digestibility of male broilers fed a wheat-based diet
Vandeplas, Sabrina ULg; Beckers, Yves ULg; Thewis, André ULg

Poster (2003)

Three experiments were conducted to investigate the mode of action of 5 hemicellulases supplemented to wheat-based broiler diets. Performances parameters and digesta viscosity were measured during growth ... [more ▼]

Three experiments were conducted to investigate the mode of action of 5 hemicellulases supplemented to wheat-based broiler diets. Performances parameters and digesta viscosity were measured during growth period. Total collection of excreta was carried out for determination of AMEn content of the diets and of apparent crude fat, Kjeldahl-nitrogen and crude cellulose digestibilities. Addition of xylanase improve daily body gain by 1 to 6% and feed conversion ration by 1,5 to 4%, as the apparent nutrient digestibility and the content of AMEn in the diets supplemented with enzymes. Although viscosity values seemed not correled to improved performances, Grindazym G shows an increase in the digesta viscosity for all the period of measurement. It can be concluded that the beneficial action of xylanases is more due to the improved release of the nutrients entrapped by the NSP, following degradation of these structures, than to the generally accepted decrease in digesta viscosity. [less ▲]

Detailed reference viewed: 39 (2 ULg)
Peer Reviewed
See detailEffect of hemodiafiltration on pulmonary hemodynamics in a model of porcin endotoxin shock
Moonen, Marie ULg; LAMBERMONT, Bernard ULg; Kolh, Philippe ULg et al

in Journal of the American Society of Nephrology [=JASN] (2001), 12

Detailed reference viewed: 4 (1 ULg)
Full Text
Peer Reviewed
See detailEffect of hemodiafiltration on pulmonary hemodynamics in endotoxic shock
Lambermont, Bernard ULg; Kolh, Philippe ULg; Ghuysen, Alexandre ULg et al

in Artificial Organs (2003), 27(12), 1128-1133

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary ... [more ▼]

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary hemodynamics during septic shock. In the Endo group, six anesthetized pigs received a 0.5 mg/kg endotoxin infusion over 30 min. In the HDF group (n = 6), HDF was started 30 min after the end of the endotoxin infusion, while in the Control group (n = 4) they received HDF but no endotoxin infusion. Pulmonary hemodynamics were analyzed in detail with a four-element windkessel model. Although in the Control group, HDF did not alter pulmonary hemodynamic parameters, in the HDF group, it was responsible for an amplification of the deleterious pulmonary vascular response to endotoxin insult. Our results show that HDF must be used cautiously in septic shock since it can precipitate right heart failure by increasing pulmonary vascular resistance. [less ▲]

Detailed reference viewed: 16 (0 ULg)
Full Text
Peer Reviewed
See detailThe effect of heterogeneity of diffusion parameters on chloride transport in low-permeability argillites
Huysmans, Marijke; Dassargues, Alain ULg

in Environmental Earth Sciences (2013), 68(7), 1835-1848

Understanding flow and transport in low-permeability media is very important in the context of nuclear waste disposal, oil and gas reservoirs and long term evolution of groundwater systems. In low ... [more ▼]

Understanding flow and transport in low-permeability media is very important in the context of nuclear waste disposal, oil and gas reservoirs and long term evolution of groundwater systems. In low-permeability media, transport by diffusion is often the most important mass transport process. This study investigates the effect of the heterogeneity of diffusion parameters on mass transport in low-permeability media. A geostatistical approach for integrating heterogeneity of diffusion parameters in groundwater flow and transport models is proposed and applied to the Toarcian argillites in France which are studied in the framework of feasibility of storing radioactive waste in deep clayey massifs. Stochastic fields of the diffusion parameters of the Toarcian argillites (France) are generated based on 64 measured values of diffusion coefficient and diffusion accessible porosity and used as input for a 3D local-scale groundwater flow and transport model. The chloride concentrations computed by these heterogeneous models are compared to the measured chloride concentrations and to concentrations calculated with a model in which the Toarcian argillites are subdivided into several homogeneous zones. The heterogeneous simulations result in a slightly better correspondence between measured and calculated values and have the additional advantage that the measured diffusion coefficient values in the Toarcian are perfectly honored in the model. This study shows that small-scale variability of diffusion parameters has a significant effect on solute concentrations and omitting this heterogeneity may be a problem in transport calculations in low-permeability media, depending on the specific setting and objectives of the study. [less ▲]

Detailed reference viewed: 47 (17 ULg)
Full Text
See detailThe effect of heterogeneity on the agreement between analytical and numerical solutions describing the recession flow in unconfined hillslope aquifers
Rocha, David; Feyen, Jan; Dassargues, Alain ULg

in Proceedings of the Int. Congress on Development, Environment and Natural Resources: Multi-level and multi-scale Sustainability (2007, July)

Analytical approximations or linearized versions of the Boussinesq equation, describing recession flow in unconfined hillslope aquifers have been applied extensively in the past. One of the major ... [more ▼]

Analytical approximations or linearized versions of the Boussinesq equation, describing recession flow in unconfined hillslope aquifers have been applied extensively in the past. One of the major assumptions in the conceptual formulation is isotropic homogeneity of the aquifer. Notwithstanding the effect of aquifer heterogeneity on recession flow has been pointed out [1], only recent studies are increasingly focusing on the quantification of this effect [2,3]. In the present research, the relevance of heterogeneity is being studied by analyzing the agreement between analytical approximations and the numerical solution of the receding flow in a layered unconfined aquifer with different domain configurations (horizontal, inclined and concave impervious bedrock). For the application of the analytical approximations use is made of the equivalent hydraulic conductivity concept. [less ▲]

Detailed reference viewed: 34 (9 ULg)
See detailThe effect of high CO2 during the first half of incubation on embryonic development after storage
Witters, A.; Debonne, M.; Everaert, Nadia ULg et al

Poster (2007)

Detailed reference viewed: 9 (0 ULg)
See detailThe effect of high CO2 during the second half of incubation on the acid-base balance regulation in the chicken embryo
Everaert, Nadia ULg; Linser, P.; Decuypere, E. et al

in Avian and Poultry Biology Reviews (2007)

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailEffect of High Doses of Oral Risedronate (20 Mg/Day) on Serum Parathyroid Hormone Levels and Urinary Collagen Cross-Link Excretion in Postmenopausal Women with Spinal Osteoporosis
Zegels, Brigitte ULg; Eastell, R.; Russell, R. G. et al

in BONE (2001), 28(1), 108-12

The present study describes the biological effects of risedronate, a pyridinyl bisphosphonate, on bone and assesses the safety and tolerability of risedronate when given at high doses, with or without ... [more ▼]

The present study describes the biological effects of risedronate, a pyridinyl bisphosphonate, on bone and assesses the safety and tolerability of risedronate when given at high doses, with or without calcium, to postmenopausal women with spinal osteoporosis. This single-center descriptive, double-blind, placebo-controlled, randomized, parallel group study included 32 postmenopausal white women with at least one radiographically confirmed vertebral compression fracture. Patients were randomized to one of four different dose regimen groups: (i) R-P, risedronate 20 mg/day for 14 days, followed by placebo for 42 days; (ii) R-CP-P, risedronate 20 mg/day for 14 days, followed by elemental calcium 1000 mg/day and placebo for 14 days, then by placebo for 28 days; (iii) R-CP-R-CP, risedronate 20 mg/day for 7 days, followed by elemental calcium 1000 mg/day and placebo for 21 days, then risedronate 20 mg/day for 7 days, and finally elemental calcium 1000 mg/day and placebo for 21 days; and (iv) P, placebo for 56 days. The biological response was investigated by measuring serum calcium, parathyroid hormone (PTH), and 2 h urinary pyridinoline/creatinine (Pyr/Cr) and deoxypyridinoline/creatinine (DPyr/Cr) ratios at baseline and at days 3, 7, 14, 21, 28, 35, 42, 49, 56, and 84. Overall, there were no consistent trends observed between the active group and placebo for serum calcium. In groups R-P, R-CP-P, and R-CP-R-CP, mean serum PTH levels were elevated above baseline values for the entire 56 day treatment period and remained elevated, although to a lesser extent, at the day 84 follow-up visit. The effect of calcium supplementation on PTH was variable. Urinary Pyr/Cr and DPyr/Cr ratios were decreased from baseline over the entire study period in all groups receiving risedronate. The maximum observed percent decreases from baseline for Pyr/Cr and DPyr/Cr were -46.9% and -58.8%, respectively, at day 49 in the R-CP-R-CP group. In conclusion, risedronate given orally at a dose of 20 mg/day, continuously for 7 or 14 days, resulted in the expected biological response in osteoporotic women. The time course of changes in PTH levels following cessation of dosing was unaffected by calcium supplementation. There was no evidence of a PTH-mediated rebound in bone resorption following cessation of therapy. Furthermore, based on collagen cross-link data, patients did not show an excessive reduction in bone turnover. [less ▲]

Detailed reference viewed: 10 (3 ULg)
Full Text
Peer Reviewed
See detailEffect of high osmolarity acclimation on tolerance to hyperosmotic shocks in L929 cultured cells.
Gilles, Raymond ULg; Belkhir, M.; Compère, Philippe ULg et al

in Tissue & Cell (1995), 27(6), 679-687

Application of abrupt, large hyperosmotic shocks induces in L929 cultured cells changes similar to those previously described in other cell types, notably a hypercondensation of the nuclear chromatin ... [more ▼]

Application of abrupt, large hyperosmotic shocks induces in L929 cultured cells changes similar to those previously described in other cell types, notably a hypercondensation of the nuclear chromatin. This paper shows that; 1) this phenomenon is concomitant with a complete disappearance of deoxyribonucleic acid, as visualized by immunogold labelling, from the nucleoplasmic spaces; 2) acclimation to high osmolarities (600 mOsm) by addition to the culture medium of NaCl, sorbitol or proline protects the cells from these effects, which appear to be largely attenuated-acclimated cells also survive much better to the osmotic shock than do control cells and; 3) the best protection seems to be provided by sorbitol and NaCl. Proline acclimation is less effective. These effects are discussed in terms of increased tolerance to NaCl load induced at the level of different macromolecules by so-called 'compensatory' organic compounds. [less ▲]

Detailed reference viewed: 34 (3 ULg)
Full Text
Peer Reviewed
See detailEffect of high temperature during embryogenesis on the sex differentiation process in the Nile tilapia, Oreochromis niloticus.
Rougeot, Carole ULg; Prignon, Christian ULg; Ngouana Kengne, Cyrille Valence et al

in Aquaculture (2008), 276

Detailed reference viewed: 67 (13 ULg)
Full Text
Peer Reviewed
See detailEffect of high-resolution spatial soil moisture variability on simulated runoff response using a distributed hydrologic model
Minet, Julien ULg; Laloy, E.; Lambot, S. et al

in Hydrology and Earth System Sciences (2011), 15

The importance of the spatial variability of antecedent soil moisture conditions on runoff response is widely acknowledged in hillslope hydrology. Using a distributed hydrologic model, this paper aims at ... [more ▼]

The importance of the spatial variability of antecedent soil moisture conditions on runoff response is widely acknowledged in hillslope hydrology. Using a distributed hydrologic model, this paper aims at investigating the effects of soil moisture spatial variability on runoff in various field conditions and at finding the structure of the soil moisture pattern that approaches the measured soil moisture pattern in terms of field scale runoff. High spatial resolution soil moisture was surveyed in ten different field campaigns using a proximal ground penetrating radar (GPR) mounted on a mobile platform. Based on these soil moisture measurements, seven scenarios of spatial structures of antecedent soil moisture were used and linked with a field scale distributed hydrological model to simulate field scale runoff. Accounting for spatial variability of soil moisture resulted in higher predicted field scale runoff as compared to the case where soil moisture was kept constant. The ranges of possible hydrographs were delineated by the extreme scenarios where soil moisture was directly and inversely modelled according to the topographic wetness index (TWI). These behaviours could be explained by the sizes and relative locations of runoff contributing areas, knowing that runoff was generated by infiltration excess over a certain soil moisture threshold. The most efficient scenario for modeling the within field spatial structure of soil moisture appeared to be when soil moisture is directly arranged according to the TWI, especially when measured soil moisture and TWI were correlated. The novelty of this work is to benefit from a large set of high-resolution soil moisture measurements allowing to model effectively the within field distribution of soil moisture and its impact on the field scale hydrograph. These observations contributed to the current knowledge of the impact of antecedent soil moisture spatial variability on the field scale runoff. [less ▲]

Detailed reference viewed: 67 (4 ULg)
Full Text
Peer Reviewed
See detailEffect of histamine on lung contractile elements in growing cattle
Jolly, Sandra ULg; Robinson, Edward; Desmecht, Daniel ULg

in American Journal of Veterinary Research (2003), 64

OBJECTIVE: To determine the effect of histamine on the contractile elements of the respiratory tract in neonatal calves and young adult cattle. SAMPLE POPULATION: Samples of trachealis muscle, bronchi ... [more ▼]

OBJECTIVE: To determine the effect of histamine on the contractile elements of the respiratory tract in neonatal calves and young adult cattle. SAMPLE POPULATION: Samples of trachealis muscle, bronchi, and intrapulmonary arteries and veins dissected from the respiratory tracts of healthy bovids (2 to 8 days and 16 to 20 months old). PROCEDURE: Histamine cumulative concentration-effect curves (10(-6) to 10(-3) M) were constructed in duplicate smooth muscle samples mounted in organ baths. Contractile responses to histamine were compared with reference contractions elicited by methacholine (10(-5) M) for airways or KCl (127 mM) for vessels. RESULTS: In young adult cattle, trachealis muscle had a substantial contractile response to histamine (84% of methacholine-induced contraction), whereas bronchi reacted slightly (15 and 20% for large and small bronchi, respectively). Although contractile responses to KCl were comparable in arteries and veins, histamine-induced contractions were greater for intrapulmonary veins than for arteries (202 vs 48% of KCl-induced contraction). In neonatal calves, histamine-induced contraction of veins also exceeded that of arteries (230 vs 54% of KCl-induced contraction); however, unlike in young adult cattle, histamine produced notable contraction of large and small bronchi (48 and 60% of methacholine-induced contraction, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Compared with intrapulmonary arteries, intrapulmonary veins have greater contractile responses to histamine in neonatal and young adult cattle. Data suggest loss of histamine responsiveness in bronchial smooth muscle as neonatal calves grow to young adults. Venodilation may be useful in treatment of lung edema in cattle. [less ▲]

Detailed reference viewed: 37 (3 ULg)
Peer Reviewed
See detailEffect of Histamine on Tumor Necrosis Factor Production by Human Monocytes
Hotermans, G.; Bury, Thierry ULg; Radermecker, Maurice ULg

in International Archives of Allergy and Applied Immunology (1991), 95(2-3), 278-81

This study was aimed at evaluating the effect of histamine on tumor necrosis factor (TNF alpha) secretion by purified human blood monocytes. TNF alpha was measured by radioimmunoassay. Histamine caused a ... [more ▼]

This study was aimed at evaluating the effect of histamine on tumor necrosis factor (TNF alpha) secretion by purified human blood monocytes. TNF alpha was measured by radioimmunoassay. Histamine caused a dose-dependent inhibition of lipopolysaccharide-induced TNF alpha production from human blood monocytes, averaging maximally 50% at 10(-5) M. Preincubation of mononuclear cells with an H2 antagonist (cimetidine), but not with an H1 antagonist (promethazine) prevented this inhibitory effect of histamine. In conclusion, histamine causes, in vitro, a depression of TNF alpha secretion by human monocytes through activation of H2 receptors. [less ▲]

Detailed reference viewed: 4 (1 ULg)