28 research outputs found
Germination and growth in control and primed seeds of pepper as affected by salt stress
Salinity is an important
abiotic stress which can affect crop
production in the world. One of the simplest
methods for improving salinity tolerance of
plants is seeds priming. This experiment
was conducted to evaluate the effects of
seeds priming with three solutions (KCl ,
NaCl and CaCl2) in germination and later
growth of three pepper (Capsicum annuum
L.) cultivars: Beldi, Baklouti and Anaheim
Chili. Seeds germination was conducted in a
completely randomized design under seven
salinity levels (0, 2, 4, 6, 8, 10 and 12 g L-1)
at room temperature for primed and control
seeds. Plants derived from these germinated
seeds (control and primed) were
transplanted and cultivated in a greenhouse
for 4 months and were irrigated permanently
with seven salinity levels (0, 2, 4, 6, 8, 10
and 12 g L-1). The results showed that
salinity affected all parameters under study
like total germination percentage and
chlorophyll level (a and b). As well, proline
content increased as response to increasing
salinity. The plants derived and grown from
primed seeds showed a considerable
tolerance to salt stress and gave better
results. In fact, priming improved the salt
resistance of pepper owing to more
chlorophyll and proline accumulation.
These results suggest that seed priming
induced possible physiological adjustments
in pepper seeds, especially in the early
stages of development, and could be used as
a suitable tool for improving germination
and growth characteristics under salt stress
conditions
La baisse de la densitĂ© osseuse au cours des maladies inflammatoires chroniques de lâintestin : prĂ©valence et facteurs de risquĂ©
Introduction: La baisse de la densité minérale osseuse représente la principale manifestation osseuse décrite au cours des maladies inflammatoires chroniques de l'intestin. En Tunisie, trÚs peu d'études ont rapportés sa prévalence et ses facteurs de risque. Le but de ce travail était de déterminer la prévalence de la perte osseuse au cours des maladies inflammatoires chroniques de l'intestin, et rechercher ses facteurs de risque. Méthodes: Patients et méthodes: étude ouverte transversale, réalisée de 2007 jusqu'à 2012. Résultats: 146 cas étaient colligés, dont 105 avaient une maladie de Crohn (71,9%) et 41 avaient une rectocolite hémorragique (28,1%). Il s'agissait de 62 hommes et 84 femmes. L'ùge moyen était de 33,18 ans. La perte osseuse était trouvée chez 85 patients (58,2%). Il s'agissait d'une ostéopénie dans 57 cas et d'ostéoporose dans 28 cas. Les facteurs de risque de perte osseuse étaient une activité physique limitée (p=0,013), un indice de masse corporel '20 kg/m2 (p=0,015), une maladie active (p=0,035), l'étendue de l'atteinte intestinale (p=0,006) et une dose cumulée de corticothérapie dépassant 4,5g de Prednisone (p=0,003). Conclusion: La déminéralisation osseuse est une complication fréquente mais non constante. Ceci justifie un dépistage précoce chez les patients à risque, qui pourront ainsi bénéficier d'un traitement substitutif.Key words: Maladie de Crohn, recto-colite hémorragique, densité minérale osseuse, ostéopénie, ostéoporos
Germination and Growth in Control and Primed Seeds of Pepper as Affected by Salt Stress
Salinity is an important
abiotic stress which can affect crop
production in the world. One of the simplest
methods for improving salinity tolerance of
plants is seeds priming. This experiment
was conducted to evaluate the effects of
seeds priming with three solutions (KCl ,
NaCl and CaCl2) in germination and later
growth of three pepper (Capsicum annuum
L.) cultivars: Beldi, Baklouti and Anaheim
Chili. Seeds germination was conducted in a
completely randomized design under seven
salinity levels (0, 2, 4, 6, 8, 10 and 12 g L-1)
at room temperature for primed and control
seeds. Plants derived from these germinated
seeds (control and primed) were
transplanted and cultivated in a greenhouse
for 4 months and were irrigated permanently
with seven salinity levels (0, 2, 4, 6, 8, 10
and 12 g L-1). The results showed that
salinity affected all parameters under study
like total germination percentage and
chlorophyll level (a and b). As well, proline
content increased as response to increasing
salinity. The plants derived and grown from
primed seeds showed a considerable
tolerance to salt stress and gave better
results. In fact, priming improved the salt
resistance of pepper owing to more
chlorophyll and proline accumulation.
These results suggest that seed priming
induced possible physiological adjustments
in pepper seeds, especially in the early
stages of development, and could be used as
a suitable tool for improving germination
and growth characteristics under salt stress
conditions
Two-step build-up of a thermoreversible polymer network: From early local to late collective dynamics
We probe the mechanisms at work in the build-up of thermoreversible gel
networks, with the help of hybrid gelatin gels containing a controlled density
of irreversible, covalent crosslinks (CL), which we quench below the physical
gelation temperature. The detailed analysis of the dependence on covalent
crosslink density of both the shear modulus and optical activity evolutions
with time after quench enables us to identify two stages of the physical
gelation process, separated by a temperature dependent crossover modulus: (i)
an early nucleation regime during which rearrangements of the triple-helix CL
play a negligible role, (ii) a late, logarithmic aging one, which is preserved,
though slowed down, in the presence of irreversible CL. We show that aging is
fully controlled by rearrangements and discuss the implication of our results
in terms of the switch from an early, local dynamics to a late, cooperative
long-range one
The impact of paper constituents on the efficiency of mechanical strengthening by polyaminoalkylalkoxysilanes
International audienceThe aim of the research was to evaluate the influence of certain components of paper such as lignin and papermaking additives (fillers and sizing) on the efficiency of a recently proposed treatment for simultaneous deacidification and mechanical strengthening with polyaminosiloxane copolymer networks. Mixed mechanical and chemical pulp papers containing various additives were treated with aminoalkylalkoxysilanes (AAAS) by immersion or by spray. Upon treatment, the deposited alkaline reserve varied from 0.34 to 1.14 mol kgâ1. For all the papers, copolymers formed from binary mixtures of a di- and a tri-functional AAAS provided the best improvement in the mechanical properties, i.e. in the tensile strength and the folding endurance, indicating an increase in the interfiber bonding energy and in the paper flexibility and plasticity, respectively. It was found that fillers had no influence while sizing hampered the efficiency of the treatment. The presence of mechanical pulp was shown to have a significant impact on the effect of the treatments as well by increasing the tensile resistance more than the folding endurance, indicating an increase in the paper rigidity. This observation was attributed to the response of lignin to the treatment
Preferential hydration fully controls the renaturation dynamics of collagen in water-glycerol solvents
Glycerol is one of the additives which stabilize collagen, as well as globular proteins, against thermally induced denaturation --an effect explained by preferential hydration, i.e. by the formation, in water/glycerol solvents, of a hydration layer whose entropic cost favors the more compact triple-helix native structure against the denatured one, gelatin. Quenching gelatin solutions promotes renaturation which, however, remains incomplete, as the formation of a gel network gives rise to growing topological constraints. So, gelatin gels exhibit glass-like dynamical features such as slow aging of their shear modulus and stretched exponential stress relaxation, the study of which gives us access to the re(de)naturation dynamics of collagen. We show that this dynamics is independent of the bulk solvent viscosity and controlled by a single parameter, the undercooling below the glycerol-concentration-dependent denaturation temperature. This provides direct proof of i) the presence of a nanometer thick, glycerol-free hydration layer, ii) the high locality of the kinetically limiting process governing renaturation