The Effect of Priming Treatments on Germination and Seedling Performance of Purslane (Portulaca oleracea) Seed Lots

This study was conducted to test the effect of a priming combination on the seed germination percentage and seedling emergence performance of purslane under climate chamber and field conditions. Four purslane seed lots were treated according five different methods, which were T1: Seeds kept at a hundred percent relative humidity for four hours at 20 °C; T2: Seeds kept at a hundred percent relative humidity for four hours at 20 °C, and then soaked in distilled water for 8 hours at 5 °C; T3: Seeds kept at a hundred percent relative humidity for four hours at 20 °C, and then soaked in distilled water for 8 hours at 20 °C; T4: Seeds soaked in distilled water for 8 hours at 5 °C; T5: Seeds soaked in distilled water for 8 hours at 20 °C; and C: Control (untreated). Seed germination was calculated for 14 days at 20 °C, seedling emergence percentages were calculated in the climatically-controlled chamber for 21 days at 22 °C, and in the field for 35 days at 15-25 °C. The highest seed germination (94%) and seedling emergence in the climatically-controlled chamber (87%) and field (82%) were obtained from seeds that had been kept at a hundred percent relative humidity for four hours at 20 °C, then soaked in distilled water for eight hours at 5 °C. Results indicated that farm-priming, can be an efficient priming method in purslane seeds

Radicle Emergence Test Estimates Predictions of Percentage Normal Seedlings in Standard Germination Tests of Aubergine (Solanum melongena L.) Seed Lots

An experiment was made to test the potential for radicle emergence (RE), and predict the germination percentage of normal seedlings both at constant (25 °C) and fluctuating (20/30 °C, 16 h/8 h) temperatures for 23 commercially available Thiram treated and untreated aubergine (Solanum melongena L.) seed lots. Frequent counts of RE at 96, 104, 112, 120, 128 and 136 hours in two different temperature regimes (constant and alternating) consistently predicted final normal germination after 14 days. The R2 values at fluctuating temperatures (R2=0.69 and 0.88, p < 0.001) were generally higher than those at a constant (R2=0.60-0.63, p < 0.01) temperature. Among the 23 seed lots, nine were Thiram threated. The R2 relationship in both temperature regimes were reduced (for Thiram-threated seed lots ranging between R2=0.60-0.79 at 25°C and 20/30°C respectively, and for untreated lots ranging between R2=0.68-0.91 at 25 °C and 20/30°C, respectively). Cumulative germination was slightly higher in the lots kept at fluctuating temperatures than in those kept at a constant temperature. The results showed that the RE test (i.e. 104 h count) can be used to make quick and repeatable predictions of the percentage of normal seedlings in aubergine lots. Moreover it was also significantly related to mean germination time (MGT) values at constant (R2= 0.769, p < 0.001) and alternating temperatures (R2= 0.861, p < 0.001)

Molecular basis for solvent dependent morphologies observed on electrosprayed surfaces

We study the causes of the observed tunable hydrophobicity of poly(styrene-co-perfluoroalkyl ethylacrylate) electrosprayed in THF, DMF, and THF : DMF (1 : 1) solvents. Under the assumption that equilibrium morphologies in the solvent significantly affect the patterns observed on electrosprayed surfaces, we use atomistic and coarse-grained simulations supported by dynamic light scattering (DLS) experiments to focus on the parameters that affect the resulting morphology of superhydrophobic electrosprayed beads. The differing equilibrium chain size distributions in these solvents examined by DLS are corroborated by chain dimensions obtained via molecular dynamics simulations. Mesoscopic morphologies monitored by dissipative particle dynamics simulations explain experimental observations; in particular, the preference of the polymer for THF over DMF in the binary mixture rationalizes the dual scale roughness driven by stable microphase separation. Drying phenomena that affect resultant dual-scale roughness are described in three stages, each interpreted by concentration dependent diffusion and surface mass transfer coefficients of the solvents. Irrespective of the presence of polar groups in the structure, a conflict between the lower-boiling point solvent adhering to the polymer and the less volatile solvent abundant in the bulk leads to perfectly hydrophobic surfaces

Solid Matrix Priming Treatment with O2 Enhanced Quality of Leek Seed Lots

This study aims to determine the effect of solid matrix priming (SMP) treatment with an air composition of O2, N2, air, vacuum on four leek (Allium ampeloprasum L.) seed lots of various ages, in terms of enhancing germination, mean germination time, electrical conductivity of solute leakage and catalase activity. Untreated seeds were used as control. Solid matrix priming at a seed: vermiculite: water ratio of 2.5:1.25:3.75 (w/w/w) was applied at 20 °C for 24 hours in the dark. Solid matrix priming with O2 was found to give the highest germination, lowest mean germination time, lowest electrical conductivity (reduced solute leakage) and the highest catalase activity among all treatments and lots. SMP treatment with air provided positive response, while N2 and vacuum treatments were found to be less effective. The advantages of solid matrix priming were more pronounced in lower quality lot than in the higher quality ones. The results indicated that oxygen enrichment in SMP may enhance leek seed quality

After-Ripening Increased Seed Germination in Commercial Aubergine Seed Lots

This work tested the effect of after-ripening on seed germination of thirteen commercial seed lots from four open pollinated cultivars (Aydın Siyahı, Kemer, Pala and Topan) of aubergine (Solanum melongena L.). Seeds were stored (after-ripened) at 5 °C with at 9% seed moisture content over 14 days in the dark in hermetic conditions. After-ripened seeds were tested at 25 °C and 20/30 °C (16/8 h) together with a control at 20/30 °C for 14 days in petri dishes. Results indicated that after-ripening significantly (p < 0.05) increased total germination in six lots and normal germination in eight lots out of thirteen when germination was tested at 25 °C. Increases were also observed eleven lots in total and thirteen in normal germination percentages out of thirteen when seeds were tested at 20/30 °C. Cumulative germination showed that after-ripened seeds germinated faster than control either germinated at 25 or 20/30 °C. Results indicated that aubergine seed germination can be increased through after-ripening treatment which shows the presence of seed dormancy in this species

A Particle Damper for Transient Oscillations

Tuned vibration absorbers, in various disguises, still form the basis of vibration suppression for light and flexible structures. These simple auxiliary components may be tuned at critical frequencies of the structure to be controlled. Tuning frequencies may be constant (in case of passive absorbers) or varied (in case of semi-active and active absorbers).Tuning ensures a strong interaction, and facilitates the transfer of the harmful energy from the problem structure to the absorber. The task then becomes to dissipate the transferred energy rapidly in the absorber, before it has a chance to return the energy back to the structure. Returning the energy back to the structure, when the rate of dissipation in the absorber is not fast enough, manifests itself as a beat, significantly deteriorating the control performance. The obvious solution to avoid the undesirable beat is to include dissipative components in the design of the tuned absorber. However, such an inclusion has two consequences. First, the effectiveness at the tuning frequency is sacrificed, at a level proportional to the amount of damping in the absorber. Second, and more critically, dissipative components are high maintenance components by nature, rendering the damped tuned absorber to be less practical. A particle damper is presented in this paper which can dissipate energy rapidly while maintaining the tuning of the absorber effectively. Simple experiments are detailed to demonstrate the tuning, and the level of dissipation

Effect of the composite curing light mode on polymerization shrinkage of resin composites

&lt;p&gt;&lt;strong&gt;Objectives:&lt;/strong&gt; The aim of this study was to investigate the effects of light curing method on the polymerization shrinkage of composite resins.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Materials and Methods:&lt;/strong&gt; Eight methods of four different light curing units were tested by forming 16 groups using two different composite types. Resin composite specimens weights were determined with an analytical electronic hydrostatic balance in the air and in water before and after curing. Then specific gravity values were determined. Volumetric polymerization shrinkage was calculated using mathematical formulas.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Results:&lt;/strong&gt; According to the results of this in-vitro study, polymerization shrinkage differed significantly among the light curing units.&lt;/p&gt; &lt;p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; When the amount of polymerization shrinkage was compared, it was determined that the curing method, which has the greatest total energy density, caused the greatest amount of shrinkage. It was also found out that some of the curing units affected the shrinkage positively in soft-start mode.&lt;/p&gt

LES of a passive control for vortex shedding from bluff bodies: comparisons with experiments and near wake topology

A passive control is numerically investigated in this paper to effectively suppress the vortex shedding from bluff bodies. To implement the control, thr ee sinusoidal leading edge configurations are considered and compared to a straight square cylinder case. Large Eddy Simulati on (LES) is used to model the wall effects, as well as the near wake. Numerical velocity fluctuations in the near wake compare well with experimental data. The LES observations provide an accurate prediction of wake instability and near wake topology, otherwise not provided experimentally. This advantage can be used for further investigation of a thorough understanding and enhancement of control. Numerical case studies are presented using the software package FLUENT and the observations are pres ented in the form of design charts, as well as velocity spectra and near wake flow details