الدكتور صفاء عبدزيد عبدعلي الخالدي

Ceratophyllum demersum considered a native common species in Iraq. The current study aimed to identify the concentration of lipid compounds in that plant using two types of solvents (Hexane and benzene: methanol mixture). The results showed that 25 compounds were identified in plants when using ben zene:methanol mixture solvents, whereas 28 compounds were found using hexane solvent. The present study concluded that the C. demersum could be a good source of many fatty acids especially Hexadecanoic acid methyl ester, Octadecadienoic acid and Phytol. Copyright 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Confer ence on Latest Developments in Materials & Manufacturing

Two polypropylene HVAC electret filters: a regular filter and an antimicrobial filter containing zinc pyrithione (ZPT), were compared for filtration performance. The study was conducted over 7 months in realistic conditions with semi-urban outdoor air. Several parameters were monitored over the study period: the average temperature was about 20 °C and relative humidity about 60%, the average inlet concentration of cultivable microorganisms was 50 CFU m−3, the average inlet concentration of particles was 10 μg m−3, the filter pressure drop increased moderately by about 30 Pa, and the particle collection efficiency of soda fluorescein (median diameter 0.35 μm) decreased in the first half of the study period by about 30% and then stabilized. The microbial concentration on the filters was quantified every 2 months using an innovative methodology based on media coupons in conjunction with microorganism quantification by CFU counting, with 5 culture media favorable to bacteria and/or fungi growth. The microbial concentrations on the filters were between 100 and 2000 CFU cm−2. The antimicrobial effect of zinc pyrithione was confirmed by the fungi cultivated with DRBC agar: no effects in the level of filter clogging were revealed in the range studied. The high statistical deviation in the results regarding the inhibiting effect of zinc pyrithione on bacteria prevents any conclusion.

Microbial growth onto HVAC filters was observed in real conditions with possible degradation of the indoor air quality. The filtration performance of marketed antimicrobial filters containing zinc pyrithione was tested under laboratory conditions and compared to that of similar filters with the same classification, F7 (EN779:2002). The filtration performance of the two tested filters during loading with PM10 particles was quantified in an experimental setup with filter pressure drop measurement and particle counting upstream and downstream of the filters. The microbial growth on the new and loaded filters, both contaminated with a microbial airborne consortium composed of two bacteria (Gram-positive and -negative) and fungi, was quantified by colony-forming units after conditioning the filters for a few days under controlled temperature (25 °C) and humidity (50% or 90% relative humidity). The results reveal that there was no degradation of the filtration performance of the filters treated with the antimicrobial agent. The efficiency of the antimicrobial treatment, i.e., the ability to inhibit the growth of microorganisms during the incubation period, was significant with the new filters regarding the fungal growth, but the results demonstrate that the antimicrobial treatment became inefficient with the loaded filters.

Indoor air quality is a topic affecting everyone’s lives, whether it is for occupational safety requirements, environmental or home health concerns. To control airborne particules in indoor environments air handling units containing at least one filtration step are proposed. Bioaerosol and more specifically microbial aerosol are of major concern in offices and public buildings. Fine filters present high filtration efficiency for microbial aerosol which size are between 0.8 and 4µm (F7 filter having a mean filtration efficiency of 80% at 0.4 µm). Once the microorganisms are collected, depending of the environmental conditions, they could develop. The aim of this study was to investigate the antimicrobial efficiency of filters containing Zinc pyrithione which is known for its effect against microorganisms. A consortium of microorganismswas aerosolized from a solution containing Staphylococcus epidermidis, Serratia marcescens (respectively Gram positive and negative bacteria) and fungal spores of Penicillium chrysogenum and was collected onto polypropylene fibrous filter media (F7 EN 779-2002). The influence of three parameters on the microbial survival onto filters was examined: air relative humidity (close to 50% and more than 90%), the effect of the presence or not of Zinc pyrithione (ZPT) as antimicrobial substances and the presence of organic particles’. Quantitative (plate counting) analyses were used to determine the survival after 8 days of the bacteria–fungi consortium collected by the filter. The results demonstrated that for normal F7 filter after 8 days at high humidity the fungal spores’ quantity present onto the filter remain constant but the gram positive bacteria decrease by 2 log and the gram negative by 1 log. In presence of ZPT the behavior was the same for Penicillium and Serratia but for Staphylococcus a 4 log decrease was observed. The lower relative humidity have a stronger effect onto the bacterial survival with no living bacteria extracted from the filter after 8 days but only a 2 log decrease for fungal spores apart from ZPT presence. Used filter clogged with organics particles could show different behaviors.

برنامج الحلقة الدراسية السنوية . بيرياك سور مير في مولان دي بريلان (فرنسا). من 13 إلى 14 أكتوبر 2016

البرنامج السنوي لملتقى الباحثين. في مدرسة الدكتوراه "العلوم الهندسية لعلم الجيولوجيا ، والهندسة المعمارية" نانت - (فرنسا). 21 أبريل 2017