Germination improvement and α-amylase and β-1,3-glucanase activity in dormant and non- dormant seeds of Oregano (Origanum vulgare)

Abstract Oregano plays a primary role among temperate culinary herbs in world trade. It is native of Southern Europe and is one of the most popular herbs in Mediterranean cooking. The germination response of this species to various germination improvement treatments including mechanical, physical and chemical scarification, were studied. Mechanical and chemical scarification of seed coat improved seed germination parameters and suggesting that O. vulgare seeds have an exogenous dormancy. Moreover, seed germination of oregano affected by other treatments such as moist chilling and chemicals, and proposing that oregano seeds also have endogenous dormancy. Standard germination test showed that germination percentage of untreated seeds is 25.8% while after chilling treatment at 4 ˚C for 7 days germination percentage reached to 39%. Soaking seeds in 100 ppm of GA 3 for 36 h resulted in 48% germination. The highest value of germination parameters detected by soaking seeds in -10 bar polyethylene glycol solution at 20 ˚C for 72 h. Total germination percentage reached to 60% in this treatment. Combination of chilling and PEG improved seed germination significantly, but was not as effective as PEG solely. Enzyme activity of α-amylase and β-1,3-glucanase in germinating seeds at 12 h after start of imbibition were assayed. Dormant seeds showed lower enzyme activity and enzyme activity in treated seeds increased significantly

Hourly Price-Based Demand Response for Optimal Scheduling of Integrated Gas and Power Networks Considering Compressed Air Energy Storage

Gas-fired plants are becoming an optimal and practical choice for power generation in electricity grids due to high efficiency and less emissions. Such plants with fast start-up capability and high ramp rate are flexible in response to stochastic load variations. Meanwhile, gas system constraints affect the flexibility and participation of such units in the energy market. Compressed air energy storage (CAES) as a flexible source with high ramp rate can be an alternative solution to reduce the impact of gas system constraints on the operation cost of a power system. In addition, demand response (DR) programs are expressed as practical approaches to overcome peak-demand challenges. This study introduces a stochastic unit commitment scheme for coordinated operation of gas and power systems with CAES technology as well as application of an hourly price-based DR. The introduced model is performed on a six-bus system with a six-node gas system to verify the satisfactory performance of the model

Experimental and Numerical Study of Lateral Collapse of Square and Rectangular Composite Tubes

Abstract -Impact is one of very important subjects which always have been considered in mechanical science. Nature of impact is such that which makes its control a hard task. Therefore it is required to present the transfer of impact to other vulnerable part of a structure, when it is necessary ,one of the best method of absorbing energy of impact, is by using Thin-walled tubes. These tubes collapses under impact and with absorption of energy, it prevents the damage to other parts. Purpose of recent study is to survey the deformation and energy absorption of tubes with different type of cross section (rectangular or square) and with similar volumes, height, mean cross section thickness, and material under lateral loading. Lateral loading of tubes are quasi-static type and beside as numerical analysis, also experimental experiences has been performed to evaluate the accuracy of the results. Results from the surveys is indicates that in a same conditions which mentioned above, samples with square cross section ,absorb more energy compare to rectangular cross section, and also by adding the number of layers of samples, energy absorption would be more

Rationale for the reactivity differences between main group and d0 transition metal complexes toward olefin polymerisation

In contrast to early transition metal complexes of d0 electron configuration, their main group metal analogues are usually poor catalysts for ethylene polymerisation due to their diminished tendency to insert ethylene into an M-R bond. Interestingly, we found that ring strain in the transition structure of the insertion reaction is most likely responsible to set the ease of the process. Ethylene insertion into an M-R bond requires a four-membered ring transition structure. Strain in a four-membered ring was shown to be dependent on the metal identity (transition or main group/d or p block). For early transition metals, due to the presence of empty valence d orbitals, the strain is negligible but, for main group metals, the strain is significant and so destabilizes the corresponding transition structure. Our claim gains support from investigation of ethylene insertion into an M-allyl bond. In this case, the relevant insertion preferentially passes through a six-membered ring transition structure with an accessibly low activation barrier. In contrast to four-membered ring transition structures, six-membered ones do not suffer significantly from ring strain, causing the insertion activation barrier to become independent of the metal identity. It becomes obvious from our study that this previously undisclosed factor should play the pivotal role in determining the reactivity of many catalysts