Physical measurements and patients’ perception of excess skin on arms and thighs before and after bariatric surgery

Background Bariatric surgery is an effective weight loss method for patients with obesity. One side effect of bariatric surgery is uncomfortable excess skin. Much remains to be learned about physical measurements and patients’ subjective perceptions of it. Here, we investigated the pre- to post-bariatric changes in patients’ perception and physical measurements of the skin on the arms and thighs, in order to find possible subgroups especially affected by post-operative excess skin and to identify predicting factors. Methods One hundred forty-seven patients eligible for bariatric surgery completed the Sahlgrenska Excess Skin Questionnaire (SESQ) and underwent measurements of their skin before and 18 months after the procedure. Results Although most physical measurements decreased post-operatively, many patients reported increased discomfort. We identified one subgroup particularly prone to report excess skin on the arms post-operatively: women with high discomfort from excess skin on the arms and high body mass index (BMI), pre-operatively. Ptosis of the excess skin seems to be a feasible measurement for predicting post-operative discomfort. For every centimetre of ptosis pre-operatively, patients had 1.37- and 1.31-fold higher odds of achieving a score for post-operative discomfort from excess skin on the upper arms and thighs, respectively, of ≥ 6 (on a 0–10 scale). Conclusions We identified a subgroup especially affected by discomforting excess skin on arms and thighs after weight loss. Furthermore, we suggest a pre-operative pro-operative ptosis measuring to predict post-operative discomfort level. The result of this study further increases the knowledge of excess skin and should be useful in further improving patient education. Level of Evidence: Level III, risk / prognostic study.

Potensi Ekstrak Daun Pepaya sebagai Inhibitor Korosi dalam Media Asam Klorida pada Baja ST37

Corrosion is a decrease in the quality of a metal material caused by a reaction with the environment. Reducing the corrosion rate on steel can be done by adding an inhibitor. Papaya leaf extract (Carica papaya.L) can be used as a corrosion inhibitor by immersion method. The effect of inhibitor on corrosion rate had been studied using weight loss method, potentiodynamic polarization method, and observation of steel surface using photooptic. It was found that corrosion rate decrease with increase concentration of papaya leaves extract. The highest inhibiton efficiency is 87.8% in 0.2 M hydrochloric acid with 2% concentration of papaya leaves extract. Potentiodynamic polarization method showed that papaya leaves extract decrease corrotion current. Inhibiton efficiency reached 81.58% in 2% extract concentration in which corrosion current decrease from 0.0266 mA/cm2 to 0.0049 mA/cm2. Analysis of photooptic showed that there is difference on steel surface corroded in hydrochloric acid with inhibitor and without it.

Assessment of Corrosive Behaviour and Microstructure Characterization of Hybrid Friction Stir Welded Martensitic Stainless Steel

This study examined the effect of induction heating on the microstructure and corrosion characteristics of hybrid friction stir welded AISI 410 stainless steel. Five joints have been produced with different friction stir welding parameters like welding speed, spindle speed, plunge depth, and induction power. Their microstructures were evaluated using a scanning electron microscope, and chemical composition was examined using energy-dispersive X-ray spectroscopy (EDX). The rate of corrosion was found out via the weight loss method in a 1 M HCL solution. The hybrid friction stir welding method used for this work is induction assisted friction stir welding; the results show that this method could produce sound AISI 410 stainless steel Joints. The experiment results show that the joint made at a spindle speed of 1150 rpm, welding speed 40 mm/min, plunge depth 0.5 mm, and in-situ heat by induction 480°C show a better corrosion resistance property with a fine grain structure.

Enhancement of corrosion resistance and mechanical properties of API 5L X60 steel by heat treatments in different environments

Steel pipelines are commonly used in the petroleum industry where high strength and durability values are required. In oil installations, the problems of corrosion, especially with crude oil, appear clearly and dramatically, in dealing with API 5L series. Improving the corrosion protection and mechanical properties are a genius goal for steel manufacturers, the heat treatment processes are familiar with this field. In this study, experimental investigations were executed to find the heat treatment influence on the corrosion rate, microstructure, and mechanical properties behavior of API 5L X60 pipeline steel in the presence of three different environments: seawater, freshwater, and crude oil. Two austenitizing temperatures 900°C and 800°C were prepared followed by quenching at 600°C, 450°C, and 300°C respectively, where the corrosion rate was estimated by the mean weight loss method. In this study, more than 60% of the corrosion rate in both seawater and freshwater was improved at 900 ºC austenitizing tempered at 300ºC for the selected pipeline specimens while only 22% reduction was achieved in crude oil. Different microstructure phases appeared in the heat-treated specimens such as tempered martensitic at 300°C and fine-grained ferrite with polygonal ferrite at 600°C. The microhardness values decreased with increasing the tempering temperatures while impact toughness values increased with tempering temperature increasing from 300°C until it was reached 450°C and then return to decrease again in 600°C.

Mechanism of Inhibitive Action of Dl-Methionine Towards the Corrosion of Mild Steel in Hydrochloric Acid Solution

DL-methionine has been investigated as inhibitor for the corrosion of mild steel in 1.0M hydrochloric acid solution using weight loss method and Scanning Electron Microscope (SEM) analysis. The investigated results showed that the inhibition efficiency increases with the increase in concentration of the inhibitor and decreases with the increase in temperature. SEM analysis indicated that the metal surface was in a better condition in the presence of inhibitor than the specimen exposed in the absence of the inhibitor. DL-methionine acted as a very good inhibitor and is also environmentally friendly, non -toxic, biodegradable and relatively cheap. Keywords: DL-methionine, mild steel, SEM, Corrosion inhibitor.

Optimization of Blended Guava and Fluted Pumpkin Leaves extract as corrosion inhibitor of mild steel in 0.5 m hydrochloric acid

There are many plant extracts that have been studied for possible use as corrosion inhibitors in the oil and gas industries. Hence, this work is focused on optimization of blended Guava and Fluted Pumpkin Leaves extract as corrosion inhibitor of mild steel in HCI using Weight loss method. Response Surface Methodology of Design Expert trial version 12 StatEase was used to design and analyze the result of the 35-run experiments. Three factor-three level was adopted in the design. Time, Temperature and Inhibitor Quantity were the independent variables, while the acid concentration of 0.5M was constant throughout the experiments and Inhibition Efficiencies were measured using IE formula. Intervals of 1 hr, 0.2g, and 10°C were chosen for the immersion time, inhibitor quantity and temperature, respectively. Phytochemical analysis carried out on the Guava and Fluted Pumpkin Leaves shows that each leaf extract contains phytochemicals which are responsible for inhibiting corrosion. Weight loss result shows that the Blended extract reduces the corrosion rate of mild steel in 0.5M HCl. Additionally, 4 experiments for Blended Extract, Fluted Pumpkin, Guava Extract and Industrial Inhibitor were carried out at optimal conditions as predicted by the software at time 4.036 hr, temperature 49.5°C, inhibitor quantity 0.487g and ratio of 59.21GE:FP40.79 Inhibition Efficiencies of the Blended, Fluted Pumpkin, Guava Extracts and Industrial Inhibitor were 93.70%, 78.14%, 63.7% and 95.18%, respectively. The results show that the blended and Industrial Inhibitor compared well with the software predicted IE of 96.085%. Therefore, the blended extract could serve as good substitute to the industrial inhibitor.

The study of thiadiazole derivatives as potential corrosion inhibitors of low-carbon steel in hydrochloric acid

The inhibition effect of series of thiadiazole derivatives against the corrosion of mild steel in 15 % HCl was studied by weight-loss method and electrochemical measurements. The experiments were performed on steel St3 at 293 K, the exposure time of the samples in solution for weight-loss measurements was 24 h. Potentiodynamic polarization curves were obtained in a typical three electrode cell with the help of electrochemical measuring complex SOLARTRON 1280 C. A scan rate was 1 mV⋅s-1 and a measurement point was taken every 0.2 s. 2-aminothiazole, 5-amino-1,3,4-thiadiazole-2-thiol, 2-amino-1,3,4-thiadiazole, 2-amino-5-(furan-2-yl)- 1,3,4-thiadiazole, 1,3,4-thiadiazole-2-ylamide of acetic acid were studied as potential inhibitors. The maximal inhibition efficiency was obtained at concentration 0.10-0.20 g⋅L−1. The best result was demonstrated by 5-amino-1,3,4-thiadiazole-2-thiol (inhibition effect was more than 90 %). The minimal inhibition effect had 1,3,4-thiadiazole-2-ylamide acetic acid. The corrosion inhibition effect calculated from data of the corrosion current density and from the weight-loss measurements were in sufficiently good agreement. The effective activation energy of the corrosion of St3 increased significantly due the presence of the inhibitors (from 3.3 to 94.8 kJ⋅mol-1). The results point to promising of investigating of series of thiadiazole derivatives and inhibitory compositions based on thiadiazole as potential acid corrosion inhibitors.

Experimental study on erosion resistance evaluation of single-layer metal mesh screen

In order to predict the erosion life and erosion failure time of the metal mesh, based on the rotating erosion experiments under different working conditions, the erosion mass loss of the metal mesh under different factors was measured by the weight loss method and the erosion mathematical prediction model was put forward. The erosion wear mechanism of the single-layer metal mesh was explored by using electron microscope scanner and optical microscope. The results show that the erosion rate increases exponentially with the increase of liquid velocity (0.5, 1.0, 1.5, 2.0 m/s). When the solid mass fraction (0.3%, 0.5%, 0.8%) and erosion Angle is 15°–45°, the erosion rate is proportional to the solid mass fraction and erosion Angle. After erosion, the mesh samples suffered different degree of pitting corrosion, ploughing and cutting wear, and the mesh wear was local wear. Compared with the experimental value, the error of the erosion mathematical model is less than 20%, which has a certain reliability, and has an important reference significance for guiding the production control of sand oil Wells.

L-Proline as a Green Corrosion Inhibitor in Aqueous Solutions for Carbon Steel

The chemical technique was used to investigate the inhibition and adsorption properties of L-proline for steel corrosion (weight loss method). As the concentration of L-proline increased, the inhibition efficiency increased, but decreased as the temperature increased, according to the findings. The inhibitor’s adsorption to the steel surface has been shown to be random, involving both electrostatic and chemisorptions. The Temkin adsorption isotherm governs the adsorption of L-proline to the steel surface. Thermodynamic parameters have been determined in some cases.