The Effect of Acupressure at GB-21 and SP-6 Acupoints on Anxiety Level and Maternal-Fetal Attachment in Primiparous Women: a Randomized Controlled Clinical Trial

Background: Delivery is one of the most stressful events in women’s life. Excessive anxiety, in turn, increases delivery and pregnancy complications. Mother’s positive experience of delivery leads to more effective maternal-fetal attachment in the first few hours of birth. Objectives: The present study aimed to compare the effects of acupressure at two different acupoints on anxiety level and maternal-fetal attachment in primiparous women. Materials and Methods: In this study, 150 primiparous women were allocated to acupressure at GB-21 acupoint, acupressure at SP-6 acupoint, and control group. The women in their active phase of delivery were enrolled in the study and pressure was applied to the acupoints for 20 minutes. Mother’s anxiety level was assessed using Spielberger’s questionnaire before and one hour after the intervention. In addition, maternal-fetal attachment behaviors were evaluated using Avant’s questionnaire during the first breastfeeding. Then the data were introduced to the SPSS (v. 13) and were analyzed using t test and one way ANOVA. Results: The results revealed no significant difference among the three groups regarding the anxiety level before the intervention (P > 0.05). One hour after the intervention, this measure was significantly lower in the intervention groups in comparison to the control group (P 0.05). Moreover, maternal-fetal attachment was higher in the intervention groups in comparison with the control group (P < 0.001). Conclusions: Acupressure at both acupoints reduced anxiety level and increased maternal-fetal attachment. This method can be easily used in the delivery room

Liquid-phase sintering of medical-grade P558 stainless steel using a new biocompatible eutectic additive

Cataloged from PDF version of article.One of the effective approaches to reduce residual pores in powder metallurgy parts is activated liquidphase sintering process using proper additives. In this work, for the first time, a new biocompatible additive (Mn–11.5 wt.% Si, a eutectic alloy) is experimented for liquid-phase sintering of nanocrystalline/amorphous P558 stainless steel powders. It is realized that by increasing the sintering aid content and temperature, the density is effectively increased: a sharp densification progress when the sintering temperature increases from 1000 °C to 1050 °C and a slower densification rate when it exceeds 1050 °C. This preliminary study opens up the development of high-density medical-grade stainless steels produced by powder metallurgy, where suitable additives can lower sintering temperature and time, which is promising for retarding grain growth and commercial applications. © 2012 Elsevier B.V. All rights reserve

Fabrication of Nanostructured Medical-Grade Stainless Steel by Mechanical Alloying and Subsequent Liquid-Phase Sintering

Cataloged from PDF version of article.This article focuses on the microstructure of medical-grade P558 (ASTM F2581) stainless steel produced by mechanical alloying and liquid-phase sintering. Rietveld X-ray diffraction and transmission electron microscopy reflect that the mechanically alloyed stainless steel powder is a nanocrystal dispersed amorphous matrix composite.Mn-11.5 wt pct Si eutectic alloy as additive improves densification of the synthesized P558 alloy via liquid-phase sintering mechanism. X-ray mapping shows that after sintering at 1323 K (105°C) for 1 hour, a uniform distribution of dissolved Mn and Si is achieved. Moreover, the development of a nanostructured, fully austenitic stainless steel after sintering at the same temperature is realized by X-ray diffraction and transmission electron microscopy. © The Minerals, Metals & Materials Society and ASM International 201

Microstructural characterization of medical-grade stainless steel powders prepared by mechanical alloying and subsequent annealing

Cataloged from PDF version of article.The harmful effect of nickel ions released from conventional stainless steel implants has provided a high level of motivation for the further development of nickel-free stainless steels. In this paper, the microstructure of medical-grade nickel-free stainless steel powders, with the chemical composition of ASTM F2581, is studied during mechanical alloying and subsequent annealing. Rietveld X-ray diffraction and transmission electron microscopy evaluations reflect nanocrystallization, austenitization and amorphization of the powders due to mechanical activation. It is also realized that annealing of the as-milled powder can develop a single austenitic structure with nanometric crystallite sizes, implying a considerable inherent resistance to grain growth. This study demonstrates the merit of mechanical alloying and subsequent annealing in the development of nanostructured medical-grade stainless steels. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserve

Compositional homogeneity in a medical-grade stainless steel sintered with a Mn-Si additive

Cataloged from PDF version of article.In this paper, chemical composition uniformity in amorphous/nanocrystallization medical-grade stainless steel (ASTM ID: F2581) sintered with a Mn–Si additive was studied via scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy. The results show that as a result of sintering at 1000 °C, no dissociation of Mn–Si additive particles embedded in the stainless steel matrix occurs. In contrast, sintering at 1050 °C develops a relatively homogeneous microstructure from the chemical composition viewpoint. The aforementioned phenomena are explained by liquation of the Mn–Si eutectic additive, thereby wetting of the main powder particles, penetrating into the particle contacts and pore zones via capillary forces, and providing a path of high diffusivity. © 2012 Elsevier B.V. All rights reserved

Effect Of Fabrication Method on The Structure and Properties of a Nanostructured Nickel-Free Stainless Steel

An ASTM F2581 nanostructured stainless steel was fabricated by two different powder metallurgy routes; Hot Powder Forging (HPF) and Binder Assisted Extrusion (BAE) methods. Their structure and mechanical properties were investigated and compared. In both fabrication methods, the alloy powder was made by using main alloying elements through mechanical alloying, along with the addition of a sintering aid. In the BAE method, a paste was prepared by mixing alloy powders with polymer followed by cold extrusion, polymer removal, and sintering. In the HPF method, the alloy powders were hot forged under high pressure. The structure and the size of the austenite crystallite of the samples were investigated by scanning electron microscopy (SEM), FE-SEM, x-ray diffraction (XRD) and transmission electron microscopy (TEM). It was determined that the samples prepared by the HPF method are generally denser than those made via BAE. The porosities are smaller and almost uniform in size and morphology in the HPF method. Furthermore, microhardness and tensile tests were performed on the samples. The results show that the ductility of BAE samples is higher than the HPF samples. The fracture surface of the BAE sample has deeper dimples, indicating higher ductility for BAE samples. On the other hand, both the hardness and strength of HPF samples are higher than those of the BAE samples. The results show that both methods produced specimens with considerably higher strength and hardness than conventional 316L stainless steel

Fabrication Of Nanocrystalline Austenitic Stainless Steel with Superior Strength and Ductility Via Binder Assisted Extrusion Method

Biomedical austenitic stainless steel (ASTM F2581) has been processed by the powder metallurgy technology using binder assisted extrusion method and aside a sintering aid. The resultant microstructure was examined by optical microscopy, field emission scanning electron microscopy, transmission electron microscopy and x-ray diffraction methods. The optical microscopy images indicate that using the binder and sintering aid considerably decreases the porosities of the sintered samples. The x-ray diffraction and transmission electron microscopy images reveal that the microstructure of the sintered alloy consists of austenite in nanocrystalline form and amorphous phases. The mechanical properties were measured through compressive tests. The mean yield strength is estimated at about 824 MPa, and the compressive strength exceeds 1GPa, which is superior to the austenitic stainless steel produced through the conventional methods. Furthermore, the process followed here is compatible with large scale industrial production at a reasonable cost