Assessing the Compressive and Impact Behavior of Plastic Safety Toe Caps through Computational Modelling

Toe caps are one of the most important components in safety footwear, but have a significant contribution to the weight of the shoe. Efforts have been made to replace steel toe caps by polymeric ones, since they are lighter, insulated and insensitive to magnetic fields. Nevertheless, polymeric solutions require larger volumes, which has a negative impact on the shoe’s aesthetics. Therefore, safety footwear manufacturers are pursuing the development of an easy, low-cost and reliable solution to optimize this component. In this work, a solid mechanics toolbox built in the open-source computational library, OpenFOAM^®, was used to simulate two laboratory standard tests (15 kN compression and 200 J impact tests). To model the polymeric material behavior, a neo-Hookean hyper-elasto-plastic material law with J2 plastic criteria was employed. A commercially available plastic toe cap was characterized, and the collected data was used for assessment purposes. Close agreements, between experimental and simulated values, were achieved for both tests, with an approximate error of 5.4% and 6.8% for the displacement value in compression and impact test simulations, respectively. The results clearly demonstrate that the employed open-source finite volume computational models offer reliable results and can support the design of toe caps for the R&D footwear industry.

Comparison of LBM and FVM in the estimation of LAD stenosis

The finite volume method (FVM)-based computational fluid dynamics (CFD) technology has been applied in the non-invasive diagnosis of coronary artery stenosis. Nonetheless, FVM is a time-consuming process. In addition to FVM, the lattice Boltzmann method (LBM) is used in fluid flow simulation. Unlike FVM solving the Navier-Stokes equations, LBM directly solves the simplified Boltzmann equation, thus saving computational time. In this study, 12 patients with left anterior descending (LAD) stenosis, diagnosed by CTA, are analysed using FVM and LBM. The velocities, pressures, and wall shear stress (WSS) predicted using FVM and LBM for each patient is compared. In particular, the ratio of the average and maximum speed at the stenotic part characterising the degree of stenosis is compared. Finally, the golden standard of LAD stenosis, invasive fractional flow reserve (FFR), is applied to justify the simulation results. Our results show that LBM and FVM are consistent in blood flow simulation. In the region with a high degree of stenosis, the local flow patterns in those two solvers are slightly different, resulting in minor differences in local WSS estimation and blood speed ratio estimation. Notably, these differences do not result in an inconsistent estimation. Comparison with invasive FFR shows that, in most cases, the non-invasive diagnosis is consistent with FFR measurements. However, in some cases, the non-invasive diagnosis either underestimates or overestimates the degree of stenosis. This deviation is caused by the difference between physiological and simulation conditions that remains the biggest challenge faced by all CFD-based non-invasive diagnostic methods.

Fetal vascular malperfusion (FVM): diagnostic implications and clinical associations

INTRODUCTION

Fetal vascular malperfusion (FVM) is diagnosed by the presence of vascular lesions in the muscularized fetal vessels in the placenta and the resultant changes in the downstream villi. The Amsterdam Placental Working Group recognizes two patterns of FVM namely segmental and global. The aim of this study was to estimate the frequency of FVM lesion in our population and to understand its neonatal associations.

METHODS

Fifty-four placentas with FVM and 56 controls collected over 34 months. The maternal and neonatal details were collected from the case charts. The patterns and grades of FVM lesions were related to the clinical factors and significance analyzed statistically using the Chi-square test and t-test and p < .05 was considered significant.

RESULTS

The frequency of FVM was 8.7%. The FVM group showed lower mean gestational age, birth weight, and placental weight with a higher frequency of IUGR. Poor neonatal survival, non-reassuring fetal status, neurological abnormalities, neonatal sepsis, asphyxia, low Apgar, and respiratory support requirement were significantly higher in the FVM group. A similar frequency of segmental and global lesions was seen. High grade lesions (n = 35) were common than low grade (n = 19). Neonatal associations were more often seen in segmental and high-grade lesions.

DISCUSSION

In the absence of antenatal diagnostic tools to identify FVM, placental examination is critical and the only definitive method to diagnose FVM, which alerts the clinician to monitor for several neonatal morbidities. Identification and typing the lesion as per the new guidelines proves significant risk associations with specific types of FVM.

Advances in nanomedicines for malaria treatment

Malaria is an infectious disease that mainly affects children and pregnant women from tropical countries. The mortality rate of people infected with malaria per year is enormous and became a public health concern. The main factor that has contributed to the success of malaria proliferation is the increased number of drug resistant parasites. To counteract this trend, research has been done in nanotechnology and nanomedicine, for the development of new biocompatible systems capable of incorporating drugs, lowering the resistance progress, contributing for diagnosis, control and treatment of malaria by target delivery. In this review, we discussed the main problems associated with the spread of malaria and the most recent developments in nanomedicine for anti-malarial drug delivery.