Analysis of trace metal contamination in Pahang River and Kelantan River, Malaysia

The primary objective of this study is to determine trace metal contamination in environmental samples obtained from Pahang River and Kelantan River, Malaysia which may help to identify the risk of sustainable dredging in these areas. This research also proceeds to compare the trace metal concentration with the National Water Quality Standards of Malaysia, Interim Canadian Sediment Quality Guidelines and Malaysian Food Act 1983 to determine its limits and risks. Samples of water, sediment, snails and fishes were collected and analyzed for As, Cu, Cd, Cr, Fe, Pb, Ni, Mn, and Hg by using atomic absorption spectrophotometer. It was found that the concentration of trace metals namely As, Cu, Cd, Cr, Pb, Ni, and Hg in river water, sediment, snail and fish samples in Pahang River were lower than the maximum allowable limits, except for Fe and Mn. In Kelantan River, the concentration of trace metals indicating that it is contaminated with Fe, Mn, Pb, Cr, Cu, Hg, and As as all trace metals exceeded the maximum allowable limits. Negative impacts may arise, and the river may contaminate more in future if there is no proper management to tackle this issue during execution of dredging activities

Эффективность фотодинамического воздействия в сочетании с озоном и хлорофиллом из листьев Dracaena angustifolia на биопленки Staphylicoccus aureus

Photodynamic inactivation is an effective treatment that uses light irradiation, photosensitizer and oxygen. The aim of this study was to determine photodynamic effectiveness of laser diode combined with ozone to reduce Staphylococcus aureus biofilm using exogenous chlorophyll (Chlo). The chlorophyll was extracted from leave of Dracaena angustifolia. To determine the antibacterial effect of S. aureus biofilm treatments, samples were separated into Chlo, Laser, Chlo+Laser, Ozone, Ozone+Laser, Chlo+Ozone+Laser categories. The data were analyzed using ANOVA test. The result of this study showed that Chlo+Ozone+Laser combine treatment at 20 s exposure of ozone with 4 min of irradiation time lead to 80.26 % reduction of biofilm activity, which was the highest efficacy of all the treatment groups. The combination of laser, chlorophyll and lower ozone concentration increases the effectiveness of photodynamic inactivation.Фотодинамическая терапия – эффективный метод инактивации бактериальных биопленок, основанный на сочетании воздействий светового излучения, фотосенсибилизатора и кислорода. Цель данного исследования – определение эффективности лазерного облу- чения в сочетании с озоном при добавлении экзогенного хлорофилла для инактивации биопленки Staphylococcus aureus (S. aureus). Хлорофилл был извлечен из листьев растения Dracaena angustifolia. В ходе исследования на образцах биопленки S. aureus оценива- лась антибактериальная активность каждого фактора в отдельности (лазерное излучение, озон, хлорофилл) и нескольких их сочета- ний (хлорофилл + лазерное облучение; озон + лазерное облучение; хлорофилл + озон + лазерное облучение). Полученные данные были проанализированы с использованием теста ANOVA. Анализ результатов исследования показал, что комбинированная обра- ботка озоном в течение 20 с в присутствии хлорофилла с последующим облучением в течение 4 мин снизила активность биопленок на 80,26%, показав самую высокую эффективность среди всех тестируемых групп. Для повышения эффективности фотодинамической терапии бактериальных биопленок рекомендуется использовать комбинацию лазерного излучения с хлорофиллом и озоном

Design of biped hip simulator using SolidWorks

The increasing number of people who underwent both hip implant surgery based on World Health Organization (WHO) has received massive attention from researchers lately to develop various types of hip simulators in order to test the hip implant. Various number of hip simulator have been developed with different functions and capabilities. This paper presents the design development of biped hip simulator using SolidWorks software by taking into consideration some improvement and modifications. The finite element method is used to test the design whether it is safe to be used or not. The biped hip simulator has been successfully designed and ready to be fabricated as the endurance testing shown a positive results. The von Mises stress induced in the material is an alloy steel which is 2,975,862.3 N/m2 lower than the yield strength. Thus, the design is safe to be used as it obey the safety criterion

Mechanical degradation model of porous fe scaffold: simulation approach

This paper proposes a simple degradation model that estimates morphological changes in pure iron scaffolding due to surface erosion. The main contribution of this work is to estimate the degradation of porous pure iron scaffolding and analyze the impact of morphological changes on mechanical properties. In this study, the pure iron scaffolding model was designed in CAD software with 3 different porosity such as 30%, 41%, and 55% respectively. The geometry images of CAD models with a resolution of 3316 x 5530 pixels are captured layer by layer with a thickness of 0.02 mm. The purpose of this method is to replace the function of the u-CT scanning technique. Two-dimensional morphological erosion is applied to reduce the number of pixels of the image model. This erosion process is adjusted iteratively with increasing number of pixels to erode the image model until the volume of the scaffold after reconstruction matches the volume of the model undergoing mathematical calculations. Their changes in the volume of scaffold geometry and degradation of mechanical properties were evaluated using finite element analysis. This study found that mechanical properties such as elastic modulus and yield strength decreased systematically during the 19 week degradation period. In addition, deformation analysis is performed on models based on finite element analysis

Human perception of slipperiness through measured COF

In this study, psychophysics (the subsets of human-centred approach) which includes the perception of slipperiness with visual and tactile cues (Chang et al., Ind Health 52:379380, 2014 [1]) are important to validate human perception of slipperiness. Subject rating was used as an instrument for data collection in human-centred approach. This study measured the perception of four different floor surfaces in five surface conditions—one dry condition and four liquid-spillage conditions. The concerned tested floor surfaces were (i) ceramic I (glazed ceramic tile), (ii) ceramic II floor (unglazed ceramic tile), (iii) epoxy floor, and (iv) porcelain floor (homogenous tile). Chi-square test was used to test the subjective scores of the floor slipperiness while Spearman’s rank correlation coefficient was used to measure the strength of association between the subjective scores of floor slipperiness and the measured COF

Quantitative and qualitative factors that leads to slip and fall incidents

This book investigates the factors that lead to slip and fall incidents and establishes a relationship between the coefficient of friction (COF), floor slipperiness and floor roughness. It also examines human perception of slipperiness through measured coefficient of friction (COF). On the basis of questionnaire surveys among manufacturing workers, it identifies potential risk factors and assesses human perceptions of slipperiness. It also uses a tribology approach to relate the interaction between contaminants, floor and footwear materials

Conclusion

Achievement of research objectives are very important. In this study, the perception of risk factor was found as the main factor affecting slip-and-fall incidents. It was evident that friction was significantly affected by footwear material, type of floor, and the presence of contaminants on the floor. In addition, roughness also found consistent with the coefficient of friction (COF). According to human perception issue, the subjects could differentiate floor slipperiness under contaminated conditions but became unsure when in rating floor slipperiness for different types of floor

Factors leading to slip-and-fall incidents

There are several factors that prompt the slip-and-fall incidents and this study focuses on seven factors. Epidemiology approach was used to determine the factors of slip-and-fall incidents, and questionnaire was selected as an instrument for data collection. Exploratory Factor Analysis (EFA) was performed to evaluate how the respondents perceived the slip-and-fall factors while Cronbach’s alpha was used to assess the internal consistency for each domain in the survey. Subsequently, the factors were ranked in accordance with the total variance recorded

The influence of peg designs on glenoid component: a finite element study

Glenoid loosening was associated with stress at the implant and cement. The purpose of this study was to determine the effect of pegs and its distribution on stress transfer to the implant and cement. Six commercially available implant designs were simulated via finite element analysis with different peg distributions. Maximum stress at the implant and cement and stress critical area (SCA) at the cement were obtained. Partially cemented implants had the ability to reduce the stress at the implant and cement by adding more fins at the central peg

The relationship between coefficient of friction (COF) with floor slipperiness and roughness

The relationship between coefficient of friction (COF) and roughness is best found using tribology approach. This study used experimental design to collect and measure the data on COF and the roughness measurement under contaminated condition. It particularly measured the COF of four different floor surfaces in five surface conditions—one dry condition and four liquid-spillage conditions. For slipperiness measurement, the analysis of variance (ANOVA) was used to determine the effect of floor, footwear, and surface condition on the measured COF. Duncan’s multiple range tests was performed to determine the sample of means that is significantly different from others. Meanwhile, Pearson’s correlation coefficient was used to measure the strength between COF and the roughness parameter