Fouling in Nanofiltration

According to Koros et al. [1] fouling is “the process resulting in loss of performance of a membrane due to deposition of suspended or dissolved substances on its external surfaces, at its pore openings, or within its pores”. Fouling is also decribed as flux decline which is irreversible and can only be removed by, for example, chemical cleaning [2]. This is different to flux decline due to solution chemistry effects or concentration polarisation which is described in more detail later in this chapter. Those flux declines can be reversed with clean water and are hence not considered as fouling

NICEST - Master Study Proposal on Next Generation Industrial Control Engineering for Sustainable Water System Treatment

[EN] In this paper a collaborative experience towards the development of a new joint master degree is presented. The design of the curriculum has as main pillars: a) to provide an interdisciplinary view and approach to advanced water treatment solutions, and b) the development of the curriculum is done according to the new challenges for Higher Education in Europe, therefore providing references of good practices with this respect. The experience is worth to be shared as in an immediate future the expected collaboration among Higher Education Institutions in Europe is to increase if an integrated and high quality Higher Education Area is to be developed. The ongoing reviewing/re-structuring process of higher education programmes provides the opportunity to promote new types and levels of learning new technologies and practices in and through pan-European collaboration. The proposal that is motivated by the need for a green approach to water treatment. Like many other industries, water and wastewater treatment plants also face the problem of a staffing shortage. Efficient and productive workers that are skilled in the business are necessary to properly manage water systems. Automation may be a potential solution to this shortage. Not only will it fill in the gaps of needed employment, but it will also put less stress on existing workers. To this aim the Next generation Industrial Control Engineering for Sustainable water system Treatment (NICEST) project is presented in this paper. © (2023) by ECOS 2023 All rights reserved.SICommission Erasmus+ Erasmus Mundus Design Measure ERASMUS-EDU-2022-EMJM-DESIGN 101082541 European Commission European Unio

Listeria monocytogenes Serogroup 1/2 Strains Have a Competitive Growth Advantage over Serotype 4b during Refrigerated Storage of an Artificially Contaminated Ready-To-Eat Pork Meat Product

Listeria monocytogenes is the bacterial causative agent of listeriosis, a life-threatening disease for humans, mainly transmitted through contaminated food. Human clinical isolates of the pathogen are frequently identified as serotype 4b strains; interestingly, however, serotype 4b (lineage I) is normally underrepresented among the food isolates in which serotype 1/2a (lineage II) is usually prevalent. The present study aimed to assess in situ dominance dynamics for the most commonly detected serotypes of L. monocytogenes implicated in foodborne listeriosis cases. A four-strain mixture comprised of L. monocytogenes serogroup 1/2 (i.e., serotypes 1/2a, 1/2b, and 1/2c) and serotype 4b food isolates was inoculated on a sliced ready-to-eat pork meat product, and dominance rates for the pathogenic strains were estimated based on serotype recoveries by utilizing multiplex polymerase chain reaction (mPCR), during storage of the product at 4 °C and 10 °C. The cumulative mPCR results showed that serotype 4b decreased at both storage temperatures, with the most abrupt decrease being noticed during storage at 10 °C. Irrespective of the storage temperature applied, L. monocytogenes strains of serogroup 1/2 predominated at the end of the meat product’s storage period. Conclusively, the preliminary findings of this research suggested a competitive growth advantage of L. monocytogenes serogroup 1/2 strains over serotype 4b during the refrigerated shelf-life of foods, thus advancing our knowledge on the pathogen’s behavior and contributing toward elucidating the manifested underrepresentation of serotype 4b in favor of serogroup 1/2 strains among the food isolates of the pathogen, particularly those recovered during detection and/or enumeration of L. monocytogenes in meat and products thereof

Biodiversity and quantification of Listeria monocytogenes in fresh meat and products thereof

Listeria monocytogenes is the causative agent of listeriosis. Despite the low incidence of the disease in humans, listeriosis is characterized by high hospitalization and case fatality rates (i.e. 20-30%), especially among individuals belonging in the YOPI segment, i.e. young, old, pregnant, and immune-compromised people. During the past three decades, the recorded cases of L. monocytogenes infections have been grown significantly due to several outbreaks of foodborne-related listeriosis. The aim of this thesis was to quantify L. monocytogenes presence and study pathogen’s biodiversity in fresh meat and products thereof. The following main objectives were set: Screening for microbial populations in naturally contaminated fresh minced pork meat and thus evaluating its microbiological quality and hygiene by conducting a field survey. Estimation of prevalence for L. monocytogenes in fresh minced pork meat and determination of the performance attributes (e.g. sensitivity, specificity) of three culture media used for the detection of pathogen in mince. Estimating the confidence intervals and uncertainties (i.e. diagnostic accuracy) for the performance attributes of each medium used for the L. monocytogenes detection, from a Bayesian perspective. Quantifying L. monocytogenes prevalence and concentration in fresh minced pork meat from presence/absence microbiological testing, through Bayesian inference.5Studying the biodiversity of L. monocytogenes in naturally contaminated fresh minced pork meat by applying molecular DNA-based typing methods (i.e. multiplex PCR, RAPD, rep-PCR).The microbial association of naturally contaminated fresh minced pork meat and its hygienic condition were established, while data for the populations of microorganisms detected were subjected to multivariate statistical analysis. All the microbiological parameters examined during the field survey, except L. monocytogenes, were reconstructed to principal components related to shelf life and meat hygiene using tools provided by multivariate analysis. The distribution of populations in mince demonstrates a classic synthesis of a microbial association, with dominance of pseudomonads.As far as L. monocytogenes is concerned, prevalence of the pathogen in minced pork meat was calculated at 22% by simultaneous (i.e. parallel) use of the PALCAM, ALOA and RAPID’L.mono selective media. None of the aforementioned media was efficient in detecting the true prevalence of L. monocytogenes in mince alone. However, the parallel use of at least two chromogenic media, such as ALOA and RAPID’L.mono, together with the application of a Bayesian modeling approach enabled the prediction of pathogen’s prevalence in fresh minced pork meat with high accuracy, without the need for further confirmation of typical L. monocytogenes colonies isolated from Petri dishes. Better handling of the uncertainty associated with other attributes of interest apart from prevalence, such as sensitivity and specificity of culture media, could be achieved through the Bayesian analysis, as well as an estimation of L. monocytogenes concentration in mince could be obtained from microbiological presence/absence testing. As a result, L. monocytogenes6concentration in minced pork meat was estimated at 14 and 17 cfu/kg of mince based on ALOA and RAPID’L.mono agars, respectively.Finally, studying biodiversity of L. monocytogenes in fresh minced pork meat through serotyping of identified isolates of the pathogen by multiplex PCR revealed the presence of serovars 1/2a (77%), 1/2b (5%), 1/2c (1%), 4b (5%) and 4ab (10%), whereas serotyping of some isolates (2%) was not feasible. RAPD and rep-PCR resulted in reproducible distinct electrophoretic DNA patterns, managing in that way to differentiate and group L. monocytogenes mince isolates into clusters with possible references to strain variability. Nevertheless, the recovery of strains sharing identical typing results indicated that similar strains were not associated with the same minced meat samples and isolation media.Ο μικροοργανισμός Listeria monocytogenes είναι το παθογόνο αίτιο της λιστερίωσης. Μολονότι η συχνότητα εμφάνισης της νόσου στον άνθρωπο είναι σχετικά μικρή, τα κρούσματα λιστεριώσεων χαρακτηρίζονται από υψηλή θνητότητα (20-30%), ιδιαιτέρως μεταξύ ατόμων που ανήκουν σε ευαίσθητες ομάδες του πληθυσμού, όπως τα νεογνά, οι ηλικιωμένοι, οι έγκυες και οι ανοσοκατεσταλμένοι. Τις τρεις τελευταίες δεκαετίες τα καταγεγραμμένα κρούσματα λιστεριώσεων έχουν αυξηθεί σημαντικά, εξαιτίας ομαδικών προσβολών από L. monocytogenes τροφιμογενούς προέλευσης. Σκοπός της παρούσας διδακτορικής διατριβής ήταν η ποσοτικοποίηση της παρουσίας και η μελέτη της βιοποικιλότητας του παθογόνου μικροοργανισμού L. monocytogenes σε νωπό κρέας και προϊόντα του. Για την επίτευξη αυτού του σκοπού τέθηκαν ως κύριοι στόχοι μελέτης οι εξής: Η διεξαγωγή έρευνας πεδίου για τη μελέτη της μικροχλωρίδας και για την εκτίμηση της μικροβιολογικής ποιότητας και υγιεινής νωπού χοίρειου κιμά. Ο υπολογισμός του επιπολασμού του μικροοργανισμού L. monocytogenes σε νωπό χοίρειο κιμά, καθώς και ο προσδιορισμός των παραμέτρων-χαρακτηριστικών επίδοσης τριών μικροβιολογικών θρεπτικών υποστρωμάτων που χρησιμοποιήθηκαν για την ανίχνευση του παθογόνου στον κιμά. Ο προσδιορισμός του διαστήματος εμπιστοσύνης και της αβεβαιότητας καθεμίας των παραμέτρων επίδοσης των χρησιμοποιούμενων υποστρωμάτων, με εφαρμογή της μπαγεσιανής προσεγγιστικής μεθόδου. Η πρόβλεψη του επιπολασμού και της συγκέντρωσης του βακτηρίου L. monocytogenes σε νωπό χοίρειο κιμά, με χρήση της μπαγεσιανής προσεγγιστικής μεθόδου.2Η μελέτη της βιοποικιλότητας του L. monocytogenes σε νωπό χοίρειο κιμά με τη βοήθεια μοριακών μεθόδων αποτύπωσης του γονιδιώματος του μικροοργανισμού, όπως είναι η πολλαπλή αλυσιδωτή αντίδραση πολυμεράσης (mPCR), η τυχαία ενίσχυση του πολυμορφικού DNA (RAPD) και η αλυσιδωτή αντίδραση πολυμεράσης επαναλαμβανόμενων στοιχείων (rep-PCR).Οι πληθυσμοί των μικροοργανισμών, πλην του L. monocytogenes, οι οποίοι προσδιορίστηκαν κατά τη διεξαγωγή της προαναφερόμενης έρευνας πεδίου, επεξεργάστηκαν μέσω της πολυμεταβλητής στατιστικής ανάλυσης. Από τις κατανομές των μικροβιακών πληθυσμών στα δείγματα του νωπού χοίρειου κιμά που αναλύθηκαν, διαπιστώθηκε η επικράτηση των ψευδομονάδων έναντι όλων των υπολοίπων ομάδων μικροοργανισμών. Με τη βοήθεια εργαλείων της πολυμεταβλητής ανάλυσης οι μικροβιακοί πληθυσμοί αναδιατάχθηκαν σε κύριες συνιστώσες σχετιζόμενες με τη μικροβιολογική ποιότητα και υγιεινή του κρέατος.Όσον αφορά στον μικροοργανισμό L. monocytogenes, για τον ακριβή υπολογισμό του επιπολασμού του στο νωπό χοίρειο κιμά έγινε παράλληλη χρήση των μικροβιολογικών υποστρώματων PALCAM, ALOA και RAPID’L.mono. Κατόπιν αυτού, ο επιπολασμός του παθογόνου στον κιμά υπολογίστηκε στο 22%. Εξάλλου, η παράλληλη χρήση δύο τουλάχιστον χρωμογόνων θρεπτικών υποστρωμάτων, όπως είναι τα ALOA και RAPID’L.mono, σε συνδυασμό με την εφαρμογή της μπαγεσιανής προσεγγιστικής μεθόδου κατέστησε δυνατή την πρόβλεψη του επιπολασμού του L. monocytogenes στο νωπό χοίρειο κιμά. Μέσω της μπαγεσιανής ανάλυσης είναι δυνατός ο καλύτερος χειρισμός της αβεβαιότητας και για άλλες παραμέτρους, εκτός του επιπολασμού του μικροοργανισμού, όπως είναι η ευαισθησία και η ικανότητα εξειδίκευσης των χρησιμοποιούμενων θρεπτικών υποστρωμάτων. Ταυτόχρονα, με χρήση των αποτελεσμάτων παρουσίας και απουσίας του3μικροοργανισμού εκτιμήθηκε η συγκέντρωση του L. monocytogenes στον κιμά σε 14 και 17 cfu/kg προϊόντος με βάση τα υποστρώματα ALOA και RAPID’L.mono αντίστοιχα.Η μελέτη της βιοποικιλότητας του L. monocytogenes σε νωπό χοίρειο κιμά με τη βοήθεια της mPCR αποκάλυψε την παρουσία των ορότυπων 1/2a (77%), 1/2b (5%), 1/2c (1%), 4b (5%) και 4ab (10%), ενώ η ορολογική τυποποίηση ορισμένων στελεχών (2%) δεν ήταν δυνατή. Οι RAPD και rep-PCR διαχώρισαν και ομαδοποίησαν ικανοποιητικά το σύνολο των στελεχών του μικροοργανισμού που απομονώθηκαν από τον κιμά, συνεισφέροντας με αυτόν τον τρόπο στη διερεύνηση της γενετικής παραλλακτικότητας του L. monocytogenes. Σε ορισμένες περιπτώσεις ωστόσο, η γενετική ομοιότητα των στελεχών δεν σχετιζόταν με την προέλευσή τους

Investigating Transcriptomic Induction of Resistance and/or Virulence in Listeria monocytogenes Cells Surviving Sublethal Antimicrobial Exposure

The potential transcriptomic induction of resistance and/or virulence in two L. monocytogenes strains belonging to the most frequent listeriosis-associated serovars (i.e., 1/2a and 4b), following their sublethal antimicrobial exposure, was studied through qPCR determination of the relative expression of 10 selected related genes (i.e., groEL, hly, iap, inlA, inlB, lisK, mdrD, mdrL, prfA, and sigB). To induce sublethal stress, three common antimicrobials (i.e., benzalkonium chloride, thymol, and ampicillin) were individually applied for 2 h at 37 °C against stationary phase cells of each strain, each at a sublethal concentration. In general, the expression of most of the studied genes remained either stable or was significantly downregulated following the antimicrobial exposure, with some strain-specific differences to be yet recorded. Thymol provoked downregulation of most of the studied genes, significantly limiting the expression of 6/10 and 4/10 genes in the strains of ser. 1/2a and ser. 4b, respectively, including those coding for the master regulators of stress response and virulence (SigB and PrfA, respectively), in both strains. At the same time, the two genes coding for the invasion internalin proteins (InlA and InlB), with crucial role in the onset of L. monocytogenes pathogenesis, were both importantly upregulated in ser. 4b strain. The results obtained increase our knowledge of the stress physiology of L. monocytogenes under certain sublethal antimicrobial conditions that could be encountered within the food chain and in clinical settings, and may assist in better and more effective mitigation strategies

Method for selecting casing diameters in wells producing low-enthalpy geothermal waters containing dissolved carbon dioxide

Most low-enthalpy geothermal waters contain dissolved gases (e.g., CO2, H2S, and CH4)- In artesian geothermal wells, the absolute pressure of the water flowing towards the surface may drop below the bubble point of the dissolved gases, resulting in their gradual release and the appearance of two-phase flow. To optimize flow conditions we must keep frictional losses to a minimum and prevent undesirable flow regimes from occurring in the well. A mechanistic model has been developed for upward two-phase flow in vertical wells, based on existing correlations for the various flow regimes. Computations have been performed using data measured in wells at the Therma-Nigrita geothermal field, Greece. The methodology presented here allows us to study the effects of changes in well casing diameter on fluid production rate and flow stability within the well, parameters that have to be considered when designing geothermal wells for further exploitation and field development. (c) 2007 CNR. Published by Elsevier Ltd. All rights reserved

Eco-Friendly Lead-Free Solder Paste Printing via Laser-Induced Forward Transfer for the Assembly of Ultra-Fine Pitch Electronic Components

Current challenges in printed circuit board (PCB) assembly require high-resolution deposition of ultra-fine pitch components (<0.3 mm and <60 μm respectively), high throughput and compatibility with flexible substrates, which are poorly met by the conventional deposition techniques (e.g., stencil printing). Laser-Induced Forward Transfer (LIFT) constitutes an excellent alternative for assembly of electronic components: it is fully compatible with lead-free soldering materials and offers high-resolution printing of solder paste bumps (<60 μm) and throughput (up to 10,000 pads/s). In this work, the laser-process conditions which allow control over the transfer of solder paste bumps and arrays, with form factors in line with the features of fine pitch PCBs, are investigated. The study of solder paste as a function of donor/receiver gap confirmed that controllable printing of bumps containing many microparticles is feasible for a gap < 100 μm from a donor layer thickness set at 100 and 150 μm. The transfer of solder bumps with resolution < 100 μm and solder micropatterns on different substrates, including PCB and silver pads, have been achieved. Finally, the successful operation of a LED interconnected to a pin connector bonded to a laser-printed solder micro-pattern was demonstrated

Shelf Life of Minced Pork in Vacuum-Adsorbed Carvacrol@Natural Zeolite Nanohybrids and Poly-Lactic Acid/Triethyl Citrate/Carvacrol@Natural Zeolite Self-Healable Active Packaging Films

Enhancing food preservation and safety using environmentally friendly techniques is urgently needed. The aim of this study was to develop food packaging films using biodegradable poly-L-lactic acid (PLA) as biopolymer and carvacrol (CV) essential oil as an antioxidant/antibacterial agent for the replacement of chemical additives. CV was adsorbed onto natural zeolite (NZ) via a new vacuum adsorption method. The novel nanohybrid CV@NZ with a high CV content contained 61.7%wt. CV. Pure NZ and the CV@NZ nanohybrid were successfully dispersed in a PLA/triethyl citrate (TEC) matrix via a melt extrusion process to obtain PLA/TEC/xCV@NZ and PLA/TEC/xNZ nanocomposite films with 5, 10, and 15%wt CV@NZ or pure NZ content. The optimum resulting film PLA/TEC/10CV@NZ contained 10%wt. CV@NZ and exhibited self-healable properties, 22% higher tensile strength, 40% higher elongation at break, 45% higher water barrier, and 40% higher oxygen barrier than the pure PLA/TEC matrix. This film also had a high CV release content, high CV control release rate as well as 2.15 mg/L half maximal effective concentration (EC50) and 0.27 mm and 0.16 mm inhibition zones against Staphylococcus aureus and Salmonella enterica ssp. enterica serovar Typhimurium, respectively. This film not only succeeded in extending the shelf life of fresh minced pork, as shown by the total viable count measurements in four days but also prevented the lipid oxidation of fresh minced pork and provided higher nutritional values of the minced meat, as revealed by the heme iron content determination. It also had much better and acceptable sensory characteristics than the commercial packaging paper

Modified stainless steel surfaces targeted to reduce fouling - Evaluation of fouling by milk components

Several stainless steel based surfaces with different properties were evaluated according to their fouling behaviour for different dairy products under different conditions. Surface properties were obtained by the following modification techniques: SiF3+, MoS22+ and TiC ion implantation; diamond-like carbon (DLC) sputtering; DLC, DLC-Si-O and SiOx, plasma enhanced chemical vapor Deposition (PECVD); autocatalytic Ni-P-PTFE and silica coating. Aqueous solutions that simulate milk (SMUF - simulated milk ultrafiltrate for the mineral components, beta-lactoglobulin for the protein components and FMF - fouling model fluid for complex milk systems) were used to study the fouling behaviour during pasteurisation. Bacteriological deposition studies were also performed with two heat resistant strains of Bacillus. The experiments were carried out at laboratory scale for the evaluation of calcium phosphate and protein deposition, and at pilot scale for adhesion of bacteria and deposits from complex milk systems. In all cases, the fouling behaviour was affected by the surface material, although in different ways for the deposition or the cleaning phases. For the non-microbiological deposits (calcium phosphate, whey protein and FMF milk-based product), the Ni-P-PTFE surface was the most promising one, since it generally promoted less deposit build up and, in all cases, was the easiest to clean. On the other hand, for bacterial adhesion, the most suitable surface was the ion implanted (TiC) surface, which also showed less spores after the cleaning process. (c) 2006 Elsevier Ltd. All rights reserved