Influence of Environmental Parameters, Pinching, and Ethephon Application on Growth and Branching of Potted Stevia

Stevia (Stevia rebaudiana) is an herb grown commercially for the extraction of intensely sweet-tasting, non-caloric, steviol glycosides produced primarily in the leaves and used as a sugar substitute. While most stevia production occurs as an industrial field crop, more recently, consumer demand for stevia for home gardens and patio containers has increased. Research on how environmental inputs impact growth, branching, and flowering of stevia under greenhouse conditions for potted plant production is currently lacking. A series of experiments was conducted to quantify how methods to promote branching, fertilizer concentration, photoperiod and temperature impact branch production, growth and development, and flowering of stevia. Both manual decapitation and ethephon application increased lateral branch production, though hard pinching (cutting plants back to leave four nodes) yielded a more desirable plant architecture. Neither temperature nor fertilizer concentration impacted the number of branches produced by plants given a hard pinch. Shoot dry biomass was similar at fertilizer concentrations (applied at each watering) of 50, 100, and 200 mg⋅L−1 N, but decreased at 300 or 400 mg⋅L−1 N. Stevia responded to photoperiod as a facultative short-day plant, with earliest flowering occurring, both in days to flower and the number of nodes produced before flowering, at photoperiods <13 hours. The number of nodes produced on the longest branch increased as temperature increased from 17 to 26 °C. Plant height and longest branch length were shorter at 17 °C than at higher temperatures. The results of these studies indicate that for potted plant production, stevia should be grown under a photoperiod of 14 hours or longer with moderate nutrient levels, a minimum temperature of 20 °C, and plants should receive one or more manual pinches to promote branching.

Investigating two−stage degradation of threshold voltage induced by off−state stress in AlGaN/GaN HEMTs

In this work, a two-step degradation phenomenon in D-mode Si3N4/AlGaN/GaN metal-insulator-semiconductor high−electron−transistors (MIS−HEMT) is discussed systematically. During off−state stress, threshold voltage shifts positively for a short duration, and is followed by a negative shift. In contrast, the off−state leakage continues to decrease throughout the entire stress. Results of varied measurement conditions indicate that carrier trapping at different regions dominates this phenomenon. It is interesting that under a large lateral electric field, electron−hole pairs are generated and will then be trapped at the gate dielectric layer. Furthermore, when increasing the stress temperature, impact ionization due to carriers from the gate electrode becomes more severe. Finally, devices with different gate insulator (GI) thicknesses are performed to verify the physical model of the degradation behavior.

Effect of Microstructure on Low-Temperature Fracture Toughness of a Submerged-Arc-Welded Low-Carbon and Low-Alloy Steel Plate

This study investigated the low-temperature fracture behavior of an 80-mm-thick low-carbon steel plate welded by submerged arc. The relationship between impact absorbed energy and ductility–brittle transition temperature (DBTT) based on the microstructures was evaluated through quantitative analysis on grain size and complex constituent phases using advanced EBSD technique. The microstructure formed differently depending on the heat affections, which determined fracture properties in a low-temperature environment. Among the various microstructures of the heat-affected zone (HAZ), acicular ferrite has the greatest resistance to low-temperature impact due to its fine interlocking formation and its high-angle grain boundaries.

Adverse Effects Of Flaming As A Surface Treatment Method For Stone Slabs Used In Road Pavements

This paper presents the results of tests on a damaged pavement made of flamed granite slabs. Due to their architectural value, the use of such pavements made of stone materials is a popular trend in Europe, especially in historic city centres. Faming is a popular method of surface treatment of stone elements, including slabs. The use of flame with a temperature around 1300°C on granite rock leads to allotropic transformations of quartz. The accompanying volume changes lead to flaking of the surface. As a result, the flaming gives the slab a natural texture and improves its anti-slip properties. As it was assessed, most slabs used in pavements exhibited characteristic edge and corner damage. Examination of the mechanical properties of rock taken from a slab revealed different results for samples taken from the high temperature impact zone and from other parts of the slab. The mineralogical tests carried out on samples from the high temperature impact zone showed changes in relation to the original mineralogical composition of granite, including the presence of glaze. These changes resulted in the accumulation of stresses, especially in the areas of slab edges and corners. The analysis of the test results was made in relation to the lack of uniform European standards for stone treatment by flaming and the lack of control procedures for this process. As a result of unrestricted flaming conditions, the originally homogeneous properties of the rock may vary within a single product and lead to its accelerated degradation during exploitation.