Microstructure and mechanical properties of forged and rolled rings made from X20Cr13 steel

The article describes the results of microstructure and mechanical properties tests (according to PN-EN ISO 6892- 1:2016-09 and PN-EN ISO 6507-1:2007), which were obtained on specimens taken from a fragment of a ring rolled in the temperature range from 1220 °C to 950 °C, with dimensions ø965/803 x 164 mm, annealed and heat-treated: quenching at the temperature of 1 030 ± 10 °C in oil and tempering at a temperature of 650 °C. The starting material for rolling was a forging with an opening of ø560/230 x 180 mm. Comparative hardness tests were also performed on specimens taken from the ring after rolling and softening annealing. The Rm>/sub>, Rp0.2 and A indices of the ring fragment after heat treatment, as assumed, were respectively: 942 MPa, 763 MPa and 17 %

Ewaluation and analysis of the large-size forged and rolled en AW – 7057 alumminum alloy ring structure

The article presents the results of tests on the structure and hardness of a large-size ring made of EN AW - 7075 aluminium alloy produced under industrial conditions at the Zarmen FPA forge according to the developed technology - a combined forging and rolling method. Studies of the ring were carried out in order to assess its structure and hardness after the forming processes. The scope of the study included microscopic observations (microstructure and EDS), X-ray phase analysis and hardness distribution measurements

Hypoglycemic effect of Rehmannie Radix Preparata (Sookjihwang) extract in streptozotocin-induced diabetic rats

Rhemannie Radix Preparata (RRP) has been previously employed in traditional oriental medicine as a treatment for diabetic thirst and improving blood flow. The aim of this study was to evaluate its hypoglycemic control by assaying the activities of key enzymes of carbohydrate metabolism in streptozotocin-(STZ)-induced diabetic rats. Further, RRP extracts were prepared in water (RRPW), in 50% ethanol (RRP50), and in 100% ethanol (RRP100), respectively, and compared for their actions in diabetic rats. The oral treatment of RRP (5 mg/kg b.w./d) to diabetic rats for 21 days resulted in a significant decline in blood glucose by 67% compared to diabetic control rats (P < 0.05). The altered activities of glucokinase, glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and acetyl CoA carboxylase (ACC) in the livers of diabetic rats were reversed significantly to near-normal levels by the administration of RRP (P < 0.05). Among the three RRP extracts, RRP100 was the most effective in terms of hypoglycemic action. However, the administration of RRP to diabetic rats did not improve insulin production. The modulatory effects of RRP100 on the attenuation of carbohydrate enzyme activities appear to hold promise for widespread use for the treatment of diabetes in the future

Hypoglycemic effect of white (Morus alba L.) and black (Morus nigra L.) mulberry fruits in diabetic rat

The aim of the present study was to investigate the hypoglycemic effect of white (Morus alba L.) and black (Morus nigra L.) mulberry fruits either used individually or in a combination on alloxan diabetic rats. These fruits are reported to be rich in antioxidants, flavonoids and phenolics that can potentially fight against diabetes mellitus. Male albino rats were divided into 5 groups: normal control, alloxan-diabetic control, diabetic rats treated with white mulberry fruit powder at 5% in the diet, diabetic rats treated with black mulberry fruit powder at 5% in the diet and diabetic rats treated with mixture of white and black mulberry fruits powder at 5% in the diet. After 4 weeks of treatment, blood glucose level, liver and kidney enzymes activity, lipid profile, lipid peroxidation and histopathological studies on liver, kidney and pancreas were evaluated. The mixture of white and black mulberry fruits showed the most significant (p < 0.05) improvement in feed efficiency ratio with increasing body weight gain, as well as decrease in blood glucose level and liver-kidney dysfunction when compared with diabetic control rats. Significant decrease in serum cholesterol, triglycerides and low density lipoprotein cholesterol (LDLc) as well as significant increase in high density lipoprotein cholesterol (HDLc) in diabetic rats was observed with all treatments. Moreover, mulberry fruits administration caused significant inhibition in lipid peroxidation and α-amylase activity. In addition, the beneficial effect of all treatments was further confirmed with histopathological examination of liver, kidney and pancreas. This study reveals hypoglycemic and hypolipidemic effects of white and black mulberry fruits either used individually or in combination as a dietary supplement in alloxan diabetic rats

Methods to Increase the Protective Effectiveness of Add-on Armour made of Perforated Ultra-High-Strength Nanobainitic Steel Plates

The mechanical properties of industrially produced perforated steel plates are obtained by hardening and low-temperature tempering to produce a martensitic microstructure. Another morphological type of steel microstructure that allows for ultra-high strength and, at the same time, a level of ductility that qualifies it for use in armour is nanobainite. Research into nanobainitic steels has led to the development of plates manufacturing technology at a level that can be implemented in industrial production, and has confirmed the high potential of this material for use as additional armour in the form of perforated plates. This paper reports the results of research aimed at developing a technology for the production of perforated armour plates made of nanobainitic steel, with properties competitive with currently available perforated steel plates on the world market with the highest protective effectiveness under conditions of multi-hit firing tests with small and medium calibre ammunition. The tests were performed on 300 260 mm plates, with the nominal thicknesses of 8 mm, 6 mm and 4 mm, produced from industrially melted nanobainitic steel NANOS-BA. The protective effectiveness of nanobainitic perforated plates in a system with a solid armour steel backing plate of 500 HBW hardness was tested by multi-hit firing, according to the procedures set out in the STANAG 4569 and AEP-55 vol. 1 specifications (adapted to the format of tested plates), against selected projectile types assigned to protection levels 2 and 3. Based on the analysis of the results of the firing tests and the macroscopic and microscopic examinations of the perforated plates before and after firing, the optimum perforation method was selected and the most favourable geometrical and dimensional arrangements of the perforations were determined for different plate thicknesses

Stable Incretin Mimetics Counter Rapid Deterioration of Bone Quality in Type 1 Diabetes Mellitus.

AIMS: Type 1 diabetes mellitus is associated with a high risk for bone fractures. Although bone mass is reduced, bone quality is also dramatically altered in this disorder. However, recent evidences suggest a beneficial effect of the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) pathways on bone quality. The aims of the present study were to conduct a comprehensive investigation of bone strength at the organ and tissue level; and to ascertain whether enzyme resistant GIP or GLP-1 mimetic could be beneficial in preventing bone fragility in type 1 diabetes mellitus. MATERIALS AND METHODS: Streptozotocin-treated mice were used as a model of type 1 diabetes mellitus. Control and streptozotocin-diabetic animals were treated for 21 days with an enzymatic-resistant GIP peptide ([D-Ala2]GIP) or with liraglutide (each at 25 nmol/kg bw, ip). Bone quality was assessed at the organ and tissue level by microCT, qXRI, 3-point bending, qBEI, nanoindentation and Fourier-transform infrared microspectroscopy. RESULTS: [D-Ala2]GIP and liraglutide treatment did prevent loss of whole bone strength and cortical microstructure in the STZ-injected mice. However, tissue material properties were significantly improved in STZ-injected animals following treatment with [D-Ala(2) ]GIP or liraglutide. CONCLUSIONS: Treatment of STZ-diabetic mice with [D-Ala2]GIP or liraglutide was capable of significantly preventing deterioration of the quality of the bone matrix. Further studies are required to further elucidate the molecular mechanisms involved and to validate whether these findings can be translated to human patients. This article is protected by copyright. All rights reserved

Reduction in podocyte density as a pathologic feature in early diabetic nephropathy in rodents: Prevention by lipoic acid treatment

BACKGROUND: A reduction in the number of podocytes and podocyte density has been documented in the kidneys of patients with diabetes mellitus. Additional studies have shown that podocyte injury and loss occurs in both diabetic animals and humans. However, most studies in animals have examined relatively long-term changes in podocyte number and density and have not examined effects early after initiation of diabetes. We hypothesized that streptozotocin diabetes in rats and mice would result in an early reduction in podocyte density and that this reduction would be prevented by antioxidants. METHODS: The number of podocytes per glomerular section and the podocyte density in glomeruli from rats and mice with streptozotocin (STZ)-diabetes mellitus was determined at several time points based on detection of the glomerular podocyte specific antigens, WT-1 and GLEPP1. The effect of insulin administration or treatment with the antioxidant, α-lipoic acid, on podocyte number was assessed. RESULTS: Experimental diabetes resulted in a rapid decline in apparent podocyte number and podocyte density. A significant reduction in podocytes/glomerular cross-section was found in STZ diabetes in rats at 2 weeks (14%), 6 weeks (18%) and 8 weeks (34%) following STZ injection. Similar declines in apparent podocyte number were found in STZ diabetes in C57BL/6 mice at 2 weeks, but not at 3 days after injection. Treatment with α-lipoic acid substantially prevented podocyte loss in diabetic rats but treatment with insulin had only a modest effect. CONCLUSION: STZ diabetes results in reduction in apparent podocyte number and in podocyte density within 2 weeks after onset of hyperglycemia. Prevention of these effects with antioxidant therapy suggests that this early reduction in podocyte density is due in part to increased levels of reactive oxygen species as well as hyperglycemia