Kinetics of the Mn ion and the free radical observed in γ-irradiated soybean (Glycine max L.)

In the present work, the kinetics of Mn²⁺ ion and radiation induced free radical in gamma irradiated soybean were investigated in detail using ESR spectroscopy in the temperature range of 130–400 K. Like other legumes, such as lentil, pea and broad bean, the EPR spectrum of untreated soybean is composed of an equally spaced sextet due to Mn²⁺ ion and a singlet resonance line both appearing at G=2.00±0.0010. Radiation was observed to cause an exponential increase in the intensity of the singlet resonance line but not creating any effect on Mn²⁺ ion resonance line intensities in the studied dose range of 1.25–15 kGy. Reversible increases of Mn²⁺ and free radical signals were observed below room temperature. Above room temperature, they both decreased and these decreases were irreversible. The kinetic features of Mn²⁺ and free radical signal intensities were studied by annealing the samples at predetermined temperature for predetermined time over the temperature range of 308–373 K. Ground soybean samples were used throughout the experiment to avoid any possible problems arising from the microwave cavity filling factor.     

Analysis of stresses during exit in interrupted cutting with champfered tools

This paper presents an analysis of the stresses in the workpiece and tool during exit in interrupted cutting with chamfered tools. An elastic-plastic finite element model is developed to examine the stress fields in the workpiece for various chamfer forms and exit angles. Eight different cases are considered. The workpiece material considered is low carbon steel (203.4 N/mm² yield stress). The geometric conditions considered include cases where the thickness of the cut h₁ is rather small (h₁ = 0.04 mm) compared to the chamfer width (L_c = 0.2 mm), as well as cases where L_c = h₁ = 0.3 mm. Chamfer angles of 5 and 20° are considered, while the exit angle is taken as 60 and 90°. For the various conditions considered, the loads on the tool are obtained and then used to analyze the stresses in the tool nose. An elastic, plane-strain finite element model is developed for the tool with a very fine mesh near the cutting edge. The material of the tool carbide inserts is considered to be homogeneous and isotropic.

The results indicate that the presence of the chamfer does not prevent the dangerous rotation of the workpiece shear angle in the negative direction. For the cases where the thickness of the cut is small compared to the chamfer width (L_c = 5h₁), the magnitude of the shear stresses near the cutting edge increases significantly when the chamfer angle is increased from 5 to 20°, and also these stresses reach levels corresponding to the shear flow strength of sintered carbides. For the cases where the thickness of cut is equal to the chamfer width, the results suggest that the build up material which is formed on the chamfer decreases the probability of tensile failure in the tool.     

Structural and ultrastructural features of the Malpighian tubules of Dolycoris baccarum (Linnaeus 1758), (Heteroptera: Pentatomidae)

The morphology and ultrastructure of the Malpighian tubules of Dolycoris baccarum were analyzed by scanning (SEM) and transmission (TEM) electron microscopy in order to determine their functional organization. The Malpighian tubules are compared with similar structures of other insects based on cell structure and functional organization. The Malpighian tubules of D. baccarum extend from the midgut–hindgut region of the digestive tract. The Malpighian tubules are divided into two regions: the proximal segment is short and flattened and the distal segment is long, stringy in shape and free in hemolymph. The tubules are generally long and narrow. There is a large number of trachea around the tubules. They consist of a single layer of epithelial cells. It is observed in the TEM observation that the epithelial cells have numerous microvilli at the apical side of the cells. At the basal side of the cells, there is a great number of membrane foldings and mitochondria among them. Besides some spherites, mitochondria, lysosome‐like bodies, and large or small granules can be distinguished in the cells. With this study, we aimed to demonstrate the ultrastructure of the Malpighian tubules of D. baccarum and differences or similarities with other species.