AOC removal and accumulation of bacteria in experimental sand filters

Ces dix dernières années, les méthodes permettant de déterminer la concentration des composés organiques assimilables par les bactéries dans de l'eau potable ont suscité de plus en plus d'intérêt envers les possibilités de prévision et de contrôle de la croissance des bactéries pendant le stockage et la distribution. La détermination dite "COA" (carbone organique aisément assimilable) introduite par VAN DER KOOIJ et. al. (1982) a été développée et appliquée dans le but de surveiller les concentrations de COA pendant le traitement, le stockage et la distribution. Sur la base des résultats, il a été établi un critère pour de l'eau potable biologiquement stable (VAN DER KOOIJ et HIJNEN, 1990). Ce critère exerce une influence sur la conception du traitement de l'eau. Ceci étant, il convient de porter davantage d'attention à l'effet des processus de traitement - et plus particulièrement des processus de filtration - sur la concentration de COA.Des expériences de filtration ont été effectuées sur de petits filtres à sable, dans des conditions de laboratoire bien déterminées. L'objectif de ces expériences consistait à déterminer (I) l'élimination du carbon organique aisément assimilable (COA) dans le filtre, pour des concentrations d'eaux affluentes différentes, (II) l'effet produit sur l'engorgement du filtre et (III) la qualité bactériologique du filtrat.De l'acétate a été ajouté à l'eau d'entrée des filtres en tant que modèle de substrat, dans une gamme de concentrations allant de 0,01 à 1 mg/l C. L'eau fournie était de l'eau potable préfiltrée à faible teneur en COA (0,005 mg ac-C eq/l). Au cours du temps de fonctionnement, la concentration de COA ainsi que le nombre de colonies dénombrées dans l'eau ont été contrôlés, de même que la perte de charge de la couche filtrante. A l'expiration du temps de fonctionnement, la concentration de matière bactérienne a été déterminée dans le sable des filtres.Dans les filtres à sable dont le temps de contact du lit vide était de 10 minutes, les concentrations d'acétate (Sac) inférieures ou égales à 0,25 mg/1 C ont été totalement éliminées. La réduction de COA pour les valeurs Sac de 0,5 et de 1,0 mg/l C atteignait 90 %. Il en a été conclu que les processus de filtration biologique peuvent fort bien être appliqués pour l'élimination de composés organiques aisément assimilables, tels l'acétate et l'éthanol qui sont fréquemment utilisés dans les processus d'élimination biologique des nitrates au cours du traitement de l'eau potable.La capacité d'élimination de l'acétate, offerte par les filtres à sable expérimentaux, était élevée par comparaison avec la réduction de COA observée dans le cas des filtres à sable utilisés pour la production d'eau potable à partir d'une eau de surface (VAN DER KOOIJ, 1984). La teneur en COA du filtrat dépassait le critère applicable à l'eau potable biologiquement stable, c'est-à-dire 0,01 mg ac-C eq/l, pour des charges volumique d'acétate (LVac), relevées sur les filtres à sable expérimentaux, supérieures à 1600 mg ac-C/(m3.h). La charge volumique critique en COA des filtres à sable, utilisés dans les installations de traitement citées plus haut, au-dessus de laquelle la teneur en COA du filtrat dépasse de critère, est estimée à environ 100 mg COA-C/(m3.h).Ces résultats indiquent que l'acétate est éliminé plus rapidement qu'une quantité équivalente de composés mesurée par détermination du COA.Par suite de la consommation d'acétate, le nombre de bactéries présentes dans le lit filtrant s'est accru. On a constaté qu'un net rapport linéaire existait entre la concentration d'acétate, d'une part, et le nombre de colonies dénombrées (par boite) sur le sable à la surface du filtre, d'autre part. L'accumulation de bactéries a été observée, même pour une concentration de COA de 0,005 mg ac-C/l, tandis que l'engorgement des filtres se produisait sous une concentration d'acétate de 0,01 mg ac-C/l. Des concentrations accrues de carbone organique ont été mesurées sur le sable, dans les premiers millimètres d'épaisseur du lit filtrant. Les résultats obtenus à la suite d'études sur le terrain, relatives à l'infiltration d'eau dans les puits de recharge, ont montré que, pour des valeurs de COA inférieures à 0,01 mg ac-C eq/l, la durée de processus n'atteignait pas un an, du fait de l'engorgement observé dans le sous-sol. Par conséquent, ta concentration de carbone organique assimilable (COA) dans l'eau utilisée pour l'infiltration doit être inférieure à 0,01 mg ac-C eq/l afin d'éviter l'engorgement biologique. Un niveau de COA similaire a été conseillé pour l'eau potable bioiogiquement stable (VAN DER KOOIJ and HIJNEN, 1990).La consommation d'acétate dans les filtres a eu comme autre conséquence l'accroissement du nombre de colonies hétérotrophes dénombrées dans l'eau, selon un rapport linéaire avec la concentration d'acétate dans l'eau affluente. Le nombre de colonies dénombrées présentes dans le filtrat s'est accru pour atteindre une valeur moyenne de 104 cfu/ml, sous une concentration d'acétate de 0,068 mg ac-C/l (charge volumique d'acétate de 400 mg ac-C/(m3.h)). Au vu de ces résultats, il a été conclu que la charge volumique en COA d'une filtration finale dans une installation de traitement des eaux devrait être limitée, entre autre afin d'éviter le recours à une post-désinfection visant à réduire le nombre de germes hétérotrophes.Using small sand filets under well defined laboratory conditions, filtration experiments were performed with tap water supplemented with acetate. The objective of these experiments was to determine the effect of different acetate concentrations on (i) the removal of easily assimilable organic carbon (AOC) in the filter (ii), the clogging of the tiller and (iii) the bacteriological quality of the filtrate.The results of the experiments revealed that the reduction capacity of biological filtration processes for acetate is relatively high. Acetate removal resulted in an increased microbiological activity in the top layer (< 1cm) of the filter bed and accumulation of bacterial matter was observed at an influent AOC concentration as low as 0.005 mg of ac-C eq/l. Clogging of the filter bed occurred at an influent acetate concentration of 0.01 mg C/l. Based on these observations it was concluded that the AOC concentration of water used for infiltration in recharge wells should be less thon 0.01 mg ac-C eq/l. This level is similar to the level advised for biologically-stable drinking water.A linear relationship was found between the acetate removal in the experimental filters and the colony count in the filtrate. It was recommended that the AOC load in the final filtration process in water treatment therefore should be limited to prevent high colony counts in the filtrate, thus leading to the use of post disinfection

Colloidal rods and spheres in partially miscible binary liquids

Different scenarios for assembling rod-like and spherical colloidal particles using binary mixtures of partially miscible liquids were investigated experimentally. Suitable rod-like colloids were developed first. The subsequent studies of colloids in binary liquids consisted, on one hand, of systems where particles were partially wetted by both phases and, on the other hand, of systems where particles were completely wetted by the minority phase. A simple method to prepare large quantities of micrometer-sized akagan eite-silica core-shell rods was developed. These were proven to be very versatile, with the possibility of modifying their properties on different levels. The aspect ratio is simply controlled by a gradual growth of the silica shells. From them, hollow silica rods and rods with an increased responsiveness to a magnetic field could be obtained in straightforward ways. Bijels were prepared by trapping rod-like particles on a percolating liquid-liquid interface. The familiar bicontinuous organization of liquid domains was observed after structural arrest. At a fixed volume per particle it is demonstrated that for rod-like particles the domain size decreases faster with increasing quantity of particles than in the case of spherical particles. Additionally, the packing of the rods at the interface was elucidated, revealing several characteristic features. In particle-stabilized droplet emulsions rapid evaporation of the continuous phase and eventual full mixing of the liquid phases can leave a cellular network of particles. The formation and eventual stability of these networks were investigated in detail with confocal microscopy. When colloids are completely wetted by the minority component of an asymmetric binary mixture there can be substantial temperature and composition regimes outside the binodal where shear-induced aggregation can take place. This happens as adsorbed layers present at the particle surfaces coalesce and bind particles through a liquid bridge. Depending on particle concentration, percolating networks can form of rods wetted by the minority phase after temperature quenching such a system just across the binodal

Dual-isotope 111In/177Lu SPECT imaging as a tool in molecular imaging tracer design

The synthesis, design and subsequent pre-clinical testing of new molecular imaging tracers are topic of extensive research in healthcare. Quantitative dual-isotope SPECT imaging is proposed here as a tool in the design and validation of such tracers, as it can be used to quantify and compare the biodistribution of a specific ligand and its nonspecific control ligand, labeled with two different radionuclides, in the same animal. Since the biodistribution results are not blurred by experimental or physiological inter-animal variations, this approach allows determination of the ligand's net targeting effect. However, dual-isotope quantification is complicated by crosstalk between the two radionuclides used and the radionuclides should not influence the biodistribution of the tracer. Here, we developed a quantitative dual-isotope SPECT protocol using combined 111Indium and 177Lutetium and tested this tool for a well-known angiogenesis-specific ligand (cRGD peptide) in comparison to a potential nonspecific control (cRAD peptide). Dual-isotope SPECT imaging of the peptides showed a similar organ and tumor uptake to single-isotope studies (cRGDfK-DOTA, 1.5±0.8%ID cm -3; cRADfK-DOTA, 0.2±0.1%ID cm -3), but with higher statistical relevance (p-value 0.007, n=8). This demonstrated that, for the same relevance, seven animals were required in case of a single-isotope test design as compared with only three animals when a dual-isotope test was used. Interchanging radionuclides did not influence the biodistribution of the peptides. Dual-isotope SPECT after simultaneous injection of 111In and 177Lu-labeled cRGD and cRAD was shown to be a valuable method for paired testing of the in vivo target specificity of ligands in molecular imaging tracer design. © 2012 John Wiley &amp; Sons, Ltd

Real-world effectiveness of abrocitinib treatment in patients with difficult-to-treat atopic dermatitis

Background: Abrocitinib is a JAK-1 selective inhibitor registered for the treatment of moderate-to-severe atopic dermatitis (AD). Although efficacy and safety have been shown in phase 3 clinical trials, data on real-world patients with a treatment history of advanced systemics are scarce. Objectives:The objective of the study was to evaluate the effectiveness and safety of abrocitinib treatment in patients with difficult-to-treat AD in daily practice. Methods: In this prospective observational single-centre study, all AD patients who started abrocitinib treatment in the context of standard care between April 2021 and December 2022 were included. Effectiveness was assessed using clinician- and patient-reported outcome measures. Adverse events were evaluated. Results: Forty-one patients were included. The majority (n = 30; 73.2%) had failed (ineffectiveness) on other targeted therapies, including JAK inhibitors (n = 14, 34%) and biologics (n = 16, 39%). Abrocitinib treatment resulted in a significant decrease in disease severity during a median follow-up period of 25 weeks (IQR 16–34). Median EASI score at baseline decreased from 14.7 (IQR 10.4–25.4) to 4.0 (IQR 1.6–11.4) at last review (p &lt; 0.001). Median NRS itch decreased from 7.0 (IQR 5–8) to 3.0 (IQR 1–2) at last review (p &lt; 0.001). The most frequently reported AEs included gastrointestinal symptoms (27.6%), acne (20.7%) and respiratory tract infections (17.2%). 16 (39%) patients discontinued abrocitinib treatment due to ineffectiveness, AEs or both (41.2%, 41.2% and 11.8%, respectively). Conclusion: Abrocitinib can be an effective treatment for patients with moderate-to-severe AD in daily practice, including non-responders to other targeted therapies.</p

Controlling the organization of colloidal sphero-cylinders using confinement in a minority phase

We demonstrate experimentally that a phase-separating host solvent can be used to organize colloidal rods into different cluster and network states. The rods are silica sphero-cylinders which are preferentially wet by the water-rich phase of an oil–water binary liquid system. By beginning with the rods dispersed in the single-fluid phase and then varying the temperature to enter the demixed regime, a precisely chosen volume of water-rich phase can be created. We then show how this can be used to create independent clusters of rods, a percolating network, a network of clusters or a system that undergoes hindered phase separation. These different modes are selected by choosing the relative volumes of the rods and the water-rich phase and by the timing of the temperature change

Baricitinib for atopic dermatitis patients who responded inadequately to dupilumab treatment:First daily practice results

Background: Baricitinib is the first JAK inhibitor registered for the treatment of moderate-to-severe atopic dermatitis (AD). Efficacy and safety were shown in clinical trials, but daily practice data is sparse. Objectives: To evaluate the effectiveness and safety of baricitinib treatment in daily practice in AD patients who have inadequately responded to dupilumab. Methods: In this prospective observational cohort study, AD patients who failed dupilumab treatment and started baricitinib treatment in context of standard care at the Erasmus MC (the Netherlands) were included. We analysed physician-reported scores and patient-reported outcome measure scores (PROMs). Results: Twenty-five patients were included. Baricitinib treatment resulted in significant improvement of Eczema Area and Severity Index (EASI) scores and PROMs. Seven patients showed a good and sustained response (EASI50), eight patients showed no response (&lt;EASI50), and five patients showed an initial response but worsening of EASI scores in time. Overall, baricitinib was well tolerated. Four patients discontinued baricitinib treatment due to ineffectiveness or side effects. Conclusions: Baricitinib can be an effective treatment for a subset of AD patients who failed dupilumab treatment in daily practice. We found three different treatment response groups including responders, temporarily responders, and non-responders.</p

Baricitinib for atopic dermatitis patients who responded inadequately to dupilumab treatment:First daily practice results

Background: Baricitinib is the first JAK inhibitor registered for the treatment of moderate-to-severe atopic dermatitis (AD). Efficacy and safety were shown in clinical trials, but daily practice data is sparse. Objectives: To evaluate the effectiveness and safety of baricitinib treatment in daily practice in AD patients who have inadequately responded to dupilumab. Methods: In this prospective observational cohort study, AD patients who failed dupilumab treatment and started baricitinib treatment in context of standard care at the Erasmus MC (the Netherlands) were included. We analysed physician-reported scores and patient-reported outcome measure scores (PROMs). Results: Twenty-five patients were included. Baricitinib treatment resulted in significant improvement of Eczema Area and Severity Index (EASI) scores and PROMs. Seven patients showed a good and sustained response (EASI50), eight patients showed no response (&lt;EASI50), and five patients showed an initial response but worsening of EASI scores in time. Overall, baricitinib was well tolerated. Four patients discontinued baricitinib treatment due to ineffectiveness or side effects. Conclusions: Baricitinib can be an effective treatment for a subset of AD patients who failed dupilumab treatment in daily practice. We found three different treatment response groups including responders, temporarily responders, and non-responders.</p

A LUENBERGER OBSERVER FOR AN INFINITE DIMENSIONAL BILINEAR SYSTEM: A UV DISINFECTION EXAMPLE

Abstract: Inspired by the UV disinfection processes in food and water treatment industry, we design a Luenberger observer which works at the boundary of the infinite dimensional bilinear system. Existence of a solution, stability and some observer design issues are shown. Simulations of a disinfection process and its observer illustrate the results