Splat taxonomy of polymeric thermal spray coating

The geometry of a powder particle and the splat that it gives rise to during the thermal spray process are key parameters that determine the physical attributes of a coating. The splat shape is an important feature that requires accurate characterization, preferably by means of a quantified metric, so that the rapid solidification process of thermal spray deposition can be understood. In this work we report on a polypropylene (PP) powder that was sprayed onto a glass substrate at room temperature using the flame spray process, at various stand-off distances (SODs). Several statistical concepts were employed using image analysis techniques that were complemented by optical microscopy, scanning electron microscopy, and 2D profilometry: methods that measured the splat metrics of formation, including an estimate of splash area. Measurement of equivalent diameter, degree of splashing, spreading factor, deposition efficiency and circularity have quantified splats so that thermal spray parameterization can be related to the process efficiency. The results of this study indicated that increasing the SOD from 10 cm to 25 cm reduced the splat thickness and deposition efficiency; while other metrics (as listed earlier) were not routinely correlated, though an increase in splash area was demonstrated. Splat circularity was steady around 0.9, indicating that the deposited particles exhibited a circular shape at all SODs

Splat formation of polypropylene flame sprayed onto a flat surface

The oxy-acetylene flame process with external powder feeding was employed to spray form polypropylene (PP) splats onto a glass substrate. This work examines the influence of stand-off distance on PP splat morphology to establish a fundamental understanding of processing variables on microstructural characteristics. Optical microscopy, scanning electron microscopy (SEM), 2D profilometry, non-contact optical surface profilometry and VISION software were used to measure and quantify various morphological features that are descriptors for the splat metrics. Micro-Raman spectroscopy was used to examine the molecular structure of the PP splats. These studies indicated that decreasing the stand-off distance from 35 to 15 cm produced coherent, integral disk-shaped splats that exhibited minimum splashing behavior. This observation has important fundamental implications concerning the structure-property relationships of polymer coatings since the design of these intrinsic building units also controls the composite nature of the coating

Effect of substrate temperature on the splat formation of flame sprayed polypropylene

Polypropylene (PP) powder particles were thermally sprayed via a flame spray onto mild steel substrates at room temperature (RT), 70 °C, 120 °C, and 170 °C. Single solidified splats were collected from polished substrates. The splat morphology was characterized using optical microscopy and scanning electron microscopy (SEM). Micro-Raman spectroscopy examined the effect of substrate preheating on the molecular structure of the PP splats. The splat-substrate interface, porosity and a qualitative interpretation of the interface adhesion were obtained by cross-sectioning and imaging using the focused ion beam (FIB) technique. This study indicated that increasing the substrate temperature from room temperature to 170 °C produces PP splats of larger diameter that would be expected to exhibit improved adhesion. The influence of preheating dominates the splat formation and splat morphology. The Raman spectra indicate that the degree of crystallinity of the PP particles rises with increasing substrate temperature. Comparison of the spectra of the feedstock and the deposited PP particles confirms that there is no thermal degradation of the material under these processing conditions. This work demonstrates the influence of substrate chemistry on the PP splat morphology. Microstructural characteristics are related to the flame spray process variables for polymeric coatings

Reproducibility of Office and Out-of-Office Blood Pressure Measurements in Children: Implications for Clinical Practice and Research

This study aimed to evaluate the reproducibility of office (OBP), ambulatory (ABP), and home blood pressure (HBP) measurements in children and adolescents, and their implications in diagnosing hypertension in clinical practice and in pediatric hypertension research. Apparently healthy children and adolescents referred for suspected hypertension were included. Measurements of 2-visit OBP, 7-day HBP, and 24-hour ABP were performed twice, 1 to 6 months apart. Reproducibility was quantified using the SD of differences between repeated measurements. The sample size of clinical trials comparing the efficacy of antihypertensive drugs using each method was calculated. Fifty-eight individuals were analyzed (mean age, 13.0±2.9 years, 60.3% boys). The reproducibility of 24-hour ABP (SD of differences 5.7/4.5 systolic/diastolic) and HBP (5.9/5.0 mm Hg) were comparable and superior to that of visit-2 OBP (9.2/7.8) and awake (6.7/5.5) or asleep ABP (7.6/6.1). As a consequence, a parallel-group comparative trial aiming to detect a difference in the effect of 2 drugs of 10 mm Hg systolic BP, would require 36 participants when using OBP measurements, 14 using 24-hour ABP, and 15 using HBP (102/34/42 respectively for detecting a 5 mm Hg difference in diastolic BP). For a crossover design trial, the corresponding sample sizes are 9/3/4 for systolic BP and 26/9/11 for diastolic, respectively. These data suggest that in children and adolescents 24-hour ABP and 7-day HBP have similar reproducibility, superior to OBP and daytime or asleep ABP. These findings have major implications in diagnosing hypertension in children in clinical practice and in designing clinical research trials in pediatric hypertension. © 2021 Lippincott Williams and Wilkins. All rights reserved

Serum bone turnover markers may be involved in the metastatic potential of lung cancer patients

The aim of this study was to investigate several bone markers in Non-Small Cell Lung (NSCLC) and Small Cell Lung (SCLC) patients experiencing or not secondary bony disease. Fasting serum levels of bone formation, bone resorption, and osteoclastogenesis markers were determined in 22 NSCLC patients with bone metastases, 18 without bone metastasis, and 28 SCLC patients. A total of 29 healthy volunteers were also included in the study. Decreased osteocalcin (OC) serum levels and increased osteopontin and ligand of the receptor of nuclear factor kB (RANKL) serum levels were detected in NCSLC patients with bone metastases while increased C-terminal crosslinking telopeptide of type I collagen and increased RANKL/OPG (osteoprotegerin) ratio were detected in SCLC patients. Increased serum levels of OPG were observed in all lung cancer patients. OPG may be actively involved in the development of lung cancer metastasis. Furthermore, OC, OPN, and RANKL in NSCLC and CTX and RANKL in SCLC patients may also have a broader role in the pathogenesis and spread of lung cancer. They also provide useful information in identifying the group of patients that may benefit from a more rigorous treatment. © 2009 Humana Press Inc

Right sited renal cell carcinoma metastasizing to the contralateral ovary: Case report and review of the literature

Ovarian metastases from renal cell carcinoma are rare, with only 22 cases reported in the literature. We report a case of a 45-year-old woman, who developed left ovarian and right adrenal metastases 3 months after diagnosis of clear cell renal cell carcinoma and review the literature. This is the fourth reported case of right renal cell carcinoma metastasizing to the left ovary. The patient is alive 4 years after resection of the ovarian tumor, treated with sunitinib. We conclude that, although rare, metastatic renal cell carcinoma should be included in the differential diagnosis of ovarian tumors with clear cell histology. © 2008 Arányi Lajos Foundation