Determination of pore size distribution in soybean seed coats by mercury porosimetry

In this work we applied mercury porosimetry for the investigation of soybean seed coats. By using this method it was possible to determine the pore size distribution and also the pore size dispersion that is present in seed coats. The results showed that for the studied soybean genotype the seed coats had a characteristic pore diameter, but deviation of this size was not negligible. Finally, the results were confirmed by electron microscopy.

New attachment achieved by guided tissue regeneration using a bioresorbable polylactic acid membrane in dogs

Created periodontal defects in dogs were randomly assigned for experimental (Guidor bioresorbable membranes) or control (conventional therapy) treatment the results showed that the new connective issue attachment was significantly greater in test sites than in controls. This new attachment averaged 2.79 +/- 0.74 mm and 1.47 +/- 0.20 mm at test and control sites, respectively (P < 0.05). Epithelial downgrowth was also reduced in the test sites (P < 0.05). No differences in bone response were found. The bioresorbable barrier was effective in blocking gingival epithelial downgrowth and connective tissue proliferation, promoting new attachment according to the principles of guided tissue regeneration.

Determination of soybean seed respiration rate by the titulation method

This trial was carried out under laboratory conditions, with three lots of Iguacu soybean seeds, to determine the respiration rate by the titulation method. A randomized complete block design was used, with four repetitions, each one of them with 50 seeds and a control without seeds for each lot. The seeds were placed in gerbox with 40 mi of KOH 0.1N, on distilled water wet blotting paper for fixing the CO2 produced by seeds respiration. The material was placed in germinator at constant 25 degrees C for 16, 24 and 48 hours. After these periods, the titulation of the fixative solution was performed with HCl 0.1N to check the respiration rate. The most deteriorated seeds were those that presented the highest respiration rates, which were measured in mg of CO2/g of dry matter, when compared with the most vigorous lots. The titulation method was suitable for the evaluation of soybean seed respiration rate because the final results separated the lots in three different quality levels that were compatible with the results obtained from the accelerated aging and emergence.

Weed seed-germination .3. bidens-pilosa L

The germination of seeds of Bidens pilosa L. colected at different places was analyzed by dose-response curves for induction and reversion of germination in seeds pre-incubated at 25 degrees C or 36 degrees C during 24 hours. Our results indicate that phytochrome is responsible for the control of seed germination id Bidens pilosa and the level of pre-existing active form of phytochrome (Pfr) above the threshold switch the seed to germinate in darkness.

Analysis of seed-germination in Piptadenia-Gonoacantha (Mart) MACBR (Leguminosae Mimosoideae)

Preliminary tests indicated 20-degrees-25-degrees-C as optimum temperature range to the germination of the seeds of P. gonoacantha. Seeds germinate both under light and dark conditions, although final percentage is always higher in latest condition. The transmission spectrum of the tegument was investigated and showed an enrichment of the light in far-red region which reaches the embryo. Consequently the white light inhibits partially germination. Another factor controlling germination was the water availability. Our results indicated that the excessive water available during imbibition inhibits the germination process. According to our results we propose that this species do not have a pioneer behavior and even though P. gonoacantha had been described as a riparian vegetation species, the germination process is strongly inhibited with excessive water during imbiibition process.

Influence of seed particle frequency on the phase formation and on the microstructure of 0.88 PZN-0.07 BT-0.05 PT ceramic

The Pechini method as well as the simultaneous addition of seeds particles and dopant solutions of BaTiO3 (BT) and PbTiO3 (PT) were used to prepare the perovskite phase 0.88 PZN-0.07 BT-0.05 PT. To study the influence of seed particle frequency on the synthesis of the PZN ceramic, two ranges of seed particle size were used: the range from 30 to 100 nm, termed small seed particles (frequency of 10(15) particles/cm(3)); and the range from 100 to 900 nm, termed large seed particles (frequency of 10(13) particles/cm(3)). The crystalline nuclei size influenced the calcining process, the sintering process and the microstructure. Samples prepared with lower seed frequency displayed more amount of pyroclore phase, need higher temperatures for sintering and showed a more heterogeneous microstructure with poor dielectric properties. (C) 2000 Elsevier B.V. Ltd and Techna S.r.l. All rights reserved.

Effect of age on seed digestion in parrots (Amazona aestiva)

The objective of this study was to compare the capacity of adult (more than 3 yr old) and young (less than 1 yr old) true parrots to digest seeds that are normally included in their diet in captivity, particularly soybean, sunflower, and corn. All the seeds were offered for 5 d with an interval of 15 d between different diets. The seeds of soybean and corn were boiled for 15 min and soaked in water at ambient temperature for 12 h before being fed to the birds. There were no differences in the digestibilities of crude protein and fats (ether extract) among animals, but the digestibilities of dry matter and crude fiber by the adult animals were higher than those of the young ones. The digestibility of carbohydrate (nitrogen-free extract) by adult birds was higher only for sunflower seeds. It is concluded that the capacity of parrots to digest fiber may change according to the age of the animal. Since the digestion of fiber depends on the action of microorganisms, these results suggest that the colonization of the gastrointestinal tract is delayed or very slow in young parrots.

Regeneration of poly-L-lysine modified carbon electrodes in the accumulation and cathodic stripping voltammetric determination of the cromoglycate anion

Cromoglycate is accumulated on a poly-L-lysine (PLL) modified carbon electrode best from pH 4 solution, where it is anionic and the PLL is cationic, and at which pH the cromoglycate gives a good reduction peak at -0.82 V. The PLL film can be regenerated readily by washing the electrode with 3 M sodium hydroxide solution, in which the PLL is deprotonated. Regeneration of the film is not required as frequently when larger amounts of PLL are incorporated into it. This allows standard addition procedures to be carried out without regenerating the electrode. Linear calibration graphs have been obtained typically in the range 0.1 - 1.5 mug ml(-1). Detection limits have been calculated to be 10 ng ml(-1). The standard addition method has been applied satisfactorily to diluted urine solutions. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Effect of pre-imbibition and osmoconditioning on seed-germination in Phaseolus-vulgaris L. under water-stress

The effect of osmoconditioning and controlled water sowing was analysed in seeds of Phaseolus vulgaris L. cv. carioca on germination under water stress conditions. The pre-sowing in water at low temperature to limit germination resulted in the increase in the tolerance to water stress. The osmoconditioning with PEG for 48 hours increased the tolerance of bean seeds to water stress of -0.51MPa. The osmoconditioning or controlled water sowing can be used as a practice to increase the tolerance of bean seeds to water stress before planting in the field.

Differences and similarities in the pore size distribution of soybean seed coats

In this work we apply the mercury porosimetry technique to determine the pore size distribution in soybean seed coats of different varieties. The analyses show that the porosity of soybean seed coats is different when seeds of different genotypes are compared. This result points the possibility of using pore size distribution to varietal discrimination.

Use of reduced concentrations of tetrazolium solutions for the evaluation of the viability of peanut seed lots

The possibility of reducing the concentration of the working solution used in the tetrazolium test for peanut seeds (Arachis hypogaea L.) with or without seedcoats was studied. Tetrazolium solutions of different concentrations (0.05%, 0.075% and 0.1%) were tested at the temperatures of 35 and 40 degrees C, for determining the time needed for the seeds to reach proper staining. The efficiency of the selected treatments in evaluating the viability potential of the seeds was determined by comparing the results of the tetrazolium tests with those obtained by standard germination (using sand and rolled paper towel as substrata) and seedling emergence in the field tests. Staining the seeds without seedcoat in 0.05% tetrazolium solution for three hours at 40 degrees C yielded efficient results. on the other hand, reduced concentrations can be employed in the staining process of seeds with seedcoat; however, this method requires a higher consumption of tetrazolium salt, longer staining time as well as a higher ability and availability of time for embryo evaluation, since the cross-cutting of seeds is much more difficult in the presence of the seedcoat and the occurrence of damage to the outer surface of the cotyledons cannot be determined.

Treatment of ligature-induced peri-implantitis by lethal photosensitization and guided bone regeneration: A preliminary histologic study in dogs

Background: the purpose of this pilot study was to evaluate the healing potential and reosseointegration in ligature-induced peri-implantitis defects adjacent to various dental implant surfaces following lethal photosensitization.Methods: A total of 36 dental implants with 4 different surface coatings (9 commercially pure titanium surface [CPTi]; 9 titanium plasma-sprayed [TPS]; 9 hydroxyapatite [HA]; and 9 acid-etched [AE]) were inserted in 6 male mongrel dogs 3 months after extraction of mandibular premolars. After a 2-month period of ligature-induced peri-implantitis and 12 months of natural peri-implantitis progression, only 19 dental implants remained. The dogs underwent surgical debridement of the remaining dental implant sites and lethal photosensitization by combination of toluidine blue O (100 mug/ml) and irradiation with diode laser. All exposed dental implant surfaces and bone craters were meticulously cleaned by mechanical means, submitted to photodynamic therapy, and guided bone regeneration (GBR) using expanded polytetrafluoroethylene (ePTFE) membranes. Five months later, biopsies of the implant sites were dissected and prepared for ground sectioning and analysis.Results: the percentage of bone fill was HA: 48.28 +/- 15.00; TPS: 39.54 +/- 12.34; AE: 26.88 +/- 22.16; and CPTi: 26.70 +/- 16.50. The percentage of reosseointegration was TPS: 25.25 +/- 11.96; CPTi: 24.91 +/- 17.78; AE: 17.30 +/- 15.41; and HA: 15.83 +/- 9.64.Conclusion: These data suggest that lethal photosensitization may have potential in the treatment of peri-implantitis.