Effect of Dissolution of η′ Precipitates on Mechanical Properties of A7075-T6 Alloy

The effects of dissolution of the η′ phase by solution treatment on the mechanical properties of A7075-T6 alloy were investigated. Immediately after solution treatment of the T6 sheet at 450 oC or higher, elongation significantly increased and dissolution of the η′ phase occurred. η′ is the main hardening phase. After natural-aging, GPI, which is coherent with the aluminum matrix, was formed and strength increased. When bake hardening after natural-aging was performed, the yield strength slightly increased due to partial dissolution of the GPI and re-precipitation of the η′ phase. In contrast, after solution treatment at 400 oC, there was less elongation increase due to the precipitation of the coarse η phase at grain boundaries and low dissolution of the η′ phase. In addition, when bake hardening after natural-aging was performed, the yield strength decreased due to insufficient GPI, which is the nucleation site of the η′ phase. To promote reprecipitation of the η′ phase, the solution treatment temperature was set to a level that would increase solubility. As a result, the yield strength was significantly increased through re-precipitation of a large number of fine and uniform η′ phase. In addition, to increase the effect of dissolution, a pre-aging treatment was introduced and the bake hardenability can be improved after dissolution.

Mechanical Properties and Microstructure Evolution of Mg-Gd Alloy during Aging Treatment

Rare-earth-containing Mg alloys are a group of widely investigated alloys due to the disperse nano-sized precipitations formed during heat treatment. The underlying formation and strengthening mechanisms of precipitation is critical for their industrial applications. In this work, we systematically studied the evolution of precipitations in a Mg-10Gd alloy, based on the atomic-scaled TEM and HAADF-STEM observations. Especially, the in-depth transition mechanism from G.P. Zone to β”, β’, βT and βM is proposed, as well as their relationships with mechanical properties. It is found that blocking effect of precipitations improves the strength significantly, according to the Orowan mechanism. The elliptic cylinder shaped β’ phase, with a base-centered orthorhombic lattice structure, provides significant strengthening effects, which enhance the hardness and ultimate tensile strength from 72 HV and 170 MPa to 120 HV and 300 MPa.

Effect of aging treatment on corrosion behavior of Mg-4Nd-2Gd-0.5Zr alloy

The effects of aging time on corrosion behavior of Mg-4Nd-2Gd-0.5Zr alloy in 3.5% NaCl solution were investigated by microanalysis, weight loss test and electrochemical test. The results show that the corrosion rate of Mg-4Nd-2Gd-0.5Zr alloy decreases first and then increases with the extension of aging time. Aging treatment alters the grain size and the distribution of the second phases. The second phases and grain size are the key factors affecting the corrosion rate of magnesium alloy. Among the tested alloys, the T6-8 h alloy shows the lowest corrosion rate, which is mainly attributed to the continuous distribution of second phases restricting the expansion of corrosion, hence the T6-8 h alloy showed the highest corrosion resistance. The corrosion rate of T6-16 h alloy increases obviously because of the growth of the grain size and the segregation of second phases, which accelerates the corrosion progress.

Sus sp. DNA ENCODING cyt b GENE DETECTION TEST ON SOFT GEL CANDY SAMPLES USING PCR METHOD

Softgel candy is soft-textured confectionery processed by the addition of several components such as gum, pectin, starch and gelatin, to obtain a supple product and packed after aging treatment first. Gelatin is one of the main components in the manufacture of soft candy derived from the hydrolysis of collagen connective tissue and animal bone that serves as the nature of gelling agents, stabilizers or emulsifiers. However, the gelatin used in products not yet labeled halal Indonesian Council of Ulama (MUI) is particularly vulnerable to pork gelatin, since pork gelatin is cheaper than cattle. The purpose of this study was to test the contaminants of pig DNA on 17 samples of soft candles not labeled halal MUI. This research used Polymerase Chain Reaction (PCR) method. Seventeen samples were isolated by DNA, then spectrophotometry was performed, followed by PCR. The PCR product is run electrophoresis. Visualize the DNA with a UV gel documentation. Primer used is primer gene encoding cyt b DNA pork. Results showed that 17 samples were negative contaminants, while the positive control of pork showed a DNA band of 149 bp. This shows that Softgel Candy 17 samples do not contain pork gelatin.

The mechanism of action of platelet-rich plasma – composition analysis and safety assessment

Aesthetic medicine is an intensively developing field, more and more focused on stimulating and regenerating the skin, rather than on emergency treatment. There are many methods used by doctors for biostimulating therapies, but the most popular procedure in recent years is the implantation of platelet-rich plasma (PRP) used to date successfully in ophthalmology, dermatology, surgery, dentistry and even in orthopedics. The procedure uses autologous material, and its essence is a repair action on damaged cells of the patient as well as the activation of healthy cells and their stimulation for more effective work. The aim of the paper is to present current knowledge about platelet-rich plasma therapy in anti-aging treatment, the effectiveness of therapy with its use, and the mechanism and safety of PRP. The composition of the autologous preparation and its use in aesthetic medicine were also analyzed. PRP is a procedure that uses the patient’s own cells, and growth factors are of key importance in the process of skin regeneration and biostimulation. The correctly performed procedure, including the appropriate collection and administration of a buffy coat to the patient and compliance with all the rules of sterility, results in positive effects of the therapy. Numerous studies prove the effectiveness and safety of the platelet-rich plasma treatment. Highly concentrated platelets in the deposited preparation stimulate the surrounding cells to angiogenesis, differentiation, proliferation and synthesis of components essential for remodeling of the treated area. The therapy is highly effective and safe to use.

Microstructure Evolution and Mechanical Properties of As-Cast and As-Compressed ZM6 Magnesium Alloys during the Two-Stage Aging Treatment Process

In the present study, different solid solution and aging processes of as-cast and as-compressed ZM6 (Mg2.6Nd0.4Zn0.4Zr) alloy were designed, and the microstructure and precipitation strengthening mechanisms were discussed. After the pre-aging treatment, a large amount of G.P. zones formed in the α-Mg matrix over the course of the subsequent secondary G.P. prescription, where the fine and dispersed Mg12(Nd,Zn) phases were precipitated at the grain boundaries. The pre-aging and secondary aging processes resulted in the Mg12(Nd, Zn) phase becoming globular, preventing grain boundary sliding and decreasing grain boundary diffusion. Meanwhile, precipitation phase â″(Mg3Nd) demonstrated a coherent relationship with the α-Mg matrix after the pre-aging process, and after the secondary aging phase, Mg12Nd increases and became semi-coherent in the matrix. Compared to an as-cast ZM6 alloy, the yield strength of the as-compressed ZM6 alloy increased sharply due to an increase in the yield strength that was proportional to the particle spacing, where the dislocation bypassed the second phase particle. Compared to the single-stage aging process, the two-stage aging process greatly improved the mechanical properties of both the as-cast and as-compressed ZM6 alloys. The difference between the as-cast and as-compressed states is that an as-compressed ZM6 alloy with more dislocations and twins has more dispersed precipitates in the G.P. zones after secondary aging, meaning that it is greatly strengthened after the two-stage aging treatment process.