Hydraulic resistance of biofilms in membrane filtration systems

Die weltweit steigende Nachfrage nach Trinkwasser geht mit immer strengeren Anforderungen an die Trinkwasserqualität einher. Membranfiltrationsprozesse (z.b. Nanofiltration und Umkehrosmose) bieten eine Möglichkeit, den strengen Anforderungen gerecht zu werden. Durch das Auftreten von Biofouling können membrangestützte Trinkwasseraufbereitungssysteme eine erhebliche Einschränkung ihrer Produktivität erfahren. Biofouling tritt ein, wenn das Biofilmwachstum auf der Membranoberfläche einen Toleranzwert überschreitet. Dies beeinflusst die Förderkanaldruckdifferenz und die transmembrane Druckdifferenz negativ, wodurch die Wasserproduktion (Permeatfluss) verringert wird. Dies erhöht die Betriebskosten der Membranfiltrationsanlage immens und kann die Wasseraufbereitung mit Membranfiltration unter wirtschaftlichen Aspekten untragbar machen. In Membranfiltrationsanlagen verhalten sich Biofilme wie eine zusätzliche Membran und fügen einen weiteren hydraulischen Widerstand zu dem der Membran hinzu. Um die Wasserproduktionsrate dennoch konstant zu halten, muss die transmembrane Druckdifferenz erhöht werden. Aufgrund ihres hohen Reibungswiderstands verringern Biofilme die Querstromgeschwindigkeit in der Filtrationseinheit. Um dem entgegen zu wirken, muss der Wasserdruck am Eingang der Filtrationseinheit erhöht werden. Eine Druckerhöhung im Membranfiltrationssystem geht immer mit einer Erhöhung der Betriebskosten einher. Biofilme können auch Auswirkungen auf die Konzentrationspolarisation in einer Membranfiltrationsanlage haben. Konzentrationspolarisation ist die Anreicherung von gelösten Substanzen auf der Membranoberfläche, welche durch die Membran zurückgehalten werden. Durch den fehlenden Querstromfluss innerhalb eines Biofilms wird die Akkumulation von Salzen begünstigt und damit die Konzentrationspolarisation verstärkt, was einen negativen Einfluss auf die Filtrationsleistung hat. Hinsichtlich der großen Bedeutung, die Biofilme für die Membranfiltration haben, war es überraschend, dass zu Beginn dieser Arbeit keine Daten über den hydraulischen Widerstand von Biofilmen und deren Einfluss auf die Membranleistung verfügbar waren. Das Ziel dieser Arbeit war die Bestimmung des hydraulischen Widerstandes von Biofilmen und die Untersuchung, wie diese von Permeatfluss, Durchflussgeschwindigkeit, Nährstoffangebot und Feed Spacer beeinflusst werden. Um den hydraulischen Widerstand von Biofilmen, die Förderkanaldruckdifferenz und die transmembrane Druckdifferenz zu messen, wurde ein kleinformatiges Membranfiltrationssystem entwickelt (Kapitel 2). Die Verwendung einer Mikrofiltrationsmembran (Porengröße 0,05 µm) verhinderte die Konzentrationspolarisation von Salzen an der Membranoberfläche, wodurch der Betrieb bei niedrigem Druck sowie die exakte Messung des hydraulischen Widerstandes der Biofilme ermöglicht wurde. Eine umfangreiche Validierung des Systems zeigte, dass dieses Filtrationssystem geeignet ist, den hydraulischen Widerstand von Biofilmen unter kontrollierten Bedingungen zu untersuchen. Die Untersuchungen in dem oben beschriebenen System wurden bei zwei Permeatflussgeschwindigkeiten (20 und 100 L m-2 h-1) und einer konstanten Querstromgeschwindigkeit (0.1 m s-1) durchgeführt (Kapitel 3). Der hydraulische Widerstand der Biofilme erreichte Werte von bis zu 50 × 1012 m−1, bei einem Permeatfluss von 20 L m-2 h-1. Ein höherer Permeatfluss hatte einen vergrößerten Biofilmwiderstand zur Folge. Der Widerstand wurde nicht durch Bakterienzellen, sondern durch extrazelluläre polymere Substanzen (EPS) verursacht. Der Biofilmwiderstand war hoch im Vergleich zu dem Widerstand der verwendeten Mikrofiltrationsmembran, jedoch niedrig im Vergleich zu dem Widerstand von Nanofiltrations- (20%) und Umkehrosmosemembranen (2%). Dennoch spielt Biofouling aufgrund einer durch Biofilme verstärkten Konzentrationspolarisation, für Nanofiltration und Umkehrosmose eine große Rolle. Ein Biofilm auf der Membranoberfläche begünstigt die Akkumulation von Salzen, was wiederum die Filtrationsleistung beeinträchtigt. Bei einem konstanten Permeatfluss von 20 L m-2 h-1 wurden die Biofilmakkumulation, der transmembrane (Biofilm-) Widerstand und die Förderkanaldruckdifferenz in Abhängigkeit von der Querstromgeschwindigkeit (0.05 und 0.20 m s-1) und dem Einsatz von Feed Spacern untersucht (Kapitel 4). Durch die Zugabe von Azetat als biologisch abbaubaren Nährstoff im Zuflusswasser (0.25 und 1.0 mg L-1 Kohlenstoff) konnte eine beschleunigte Biofilmakkumulation erreicht werden. Die Untersuchungen zeigten, dass die Entstehung von Biofilmen in Membransystemen sowohl die Förderkanaldruckdifferenz als auch die transmembrane Druckdifferenz ansteigen lässt. Der hydraulische Widerstand des Biofilms stieg durch (i) erhöhtes Nährstoffangebot, (ii) erhöhte Querstromgeschwindigkeit und (iii) die Verwendung eines Feed Spacers. Die häufig in der Praxis angewendeten Produktionsparameter in Membranfiltrationsanlagen (hohe Querstromgeschwindigkeiten und Feed Spacer Anwendung) verstärken die Auswirkungen von Biofouling auf die Membraneffizienz. Die Ergebnisse dieser Arbeit sowie mögliche zukünftige Forschungsansätze für Biofouling-Untersuchungen werden in Kapitel 5 diskutiert. Die Transformation von Biofilmen zu einem Biofouling Problem kann durch die Senkung des Nährstoffgehalts im Zuflusswasser, einen niedrigen Permeatfluss und eine niedrige Querstromgeschwindigkeit hinausgezögert werden. Die Konzentrationspolarisation könnte einerseits durch eine niedrigere Querstromgeschwindigkeit erhöht, andererseits durch einen niedrigeren Permeatfluss wieder verringert werden. Der Nährstoffgehalt innerhalb der Filtrationseinheit wird jedoch durch eine niedrige Querstromgeschwindigkeit verringert. Biofouling-Hemmung durch Reduzierung der Nährstoffe ist keine neue Erfindung, aber dennoch eine der effektivsten Lösungen um das Biofouling-Problem hinauszuzögern. Zukünftige Studien sollten sich mit den Auswirkungen von modifizierten Betriebsparametern und angepassten Feed Spacern auf die Effizienz der Membransysteme, die Konzentrationspolarisation und die nötige Reinigungsfrequenz beschäftigen. Eine Anwendung und Erforschung in „real life“ Umgebungen wäre wünschenswert.The demand for drinking water in the world is increasing and water quality regulations become more stringent. High quality water can be produced with membrane filtration processes such as nanofiltration and reverse osmosis systems. A serious limitation in the application of these membrane processes for water treatment is biofouling. Biofouling occurs when the growth of biofilms negatively impacts membrane performance parameters like feed channel pressure drop and transmembrane pressure drop leading to a reduced water production (permeate flux). Biofouling increases the costs of plant operation strongly, and may even be prohibitive for the application of membrane filtration in water treatment. A biofilm acts like a secondary membrane on top of the filtration membrane adding an additional hydraulic resistance to the filtration system requiring an increase in transmembrane pressure to keep the production rate constant. Biofilms also lower the crossflow velocity inside a membrane module due to a high friction resistance. In order to maintain a steady transport of water throughout the whole filtration system higher feed pressures have to be applied. An increase in pressure always increases the operational costs. Concentration polarization, the accumulation of a solute at the membrane surface which is caused by the solute rejection of the membrane, can be influenced by the presence of biofilms as well. The lack of crossflow inside the biofilm enhances the accumulation of salts which leads to concentration polarization and decreases the performance. Regarding the importance of biofilms it is surprising that at the start of this PhD study, no data was available on the intrinsic hydraulic resistance of biofilms and its impact on membrane performance. The main objective of this thesis was to determine the hydraulic resistance of biofilms and how it was affected by (operational) parameters such as permeate flux, crossflow velocity, biodegradable substrate content, and feed spacer presence. A monitor was developed to assess the (i) hydraulic biofilm resistance and (ii) performance parameters feed channel pressure drop and transmembrane pressure drop (Chapter 2). By using a microfiltration membrane (pore size 0.05 μm) salt concentration polarization was avoided, allowing operation at low pressures enabling accurate measurement of the hydraulic biofilm resistance. Extensive validation tests showed that the small-sized monitor is a suitable tool to study the hydraulic biofilm resistance under controlled conditions. With the developed monitor system studies were performed at two fluxes (20 and 100 L m-2 h-1) and constant crossflow velocity (0.1 m s-1) (Chapter 3). The biofilm resistance reached values up to 50 × 1012 m−1 at a flux of 20 L m-2 h-1. An increased permeate flux (rate of water production) caused a higher resistance. The resistance was not caused by bacterial cells but by the extracellular polymeric substances (EPS) matrix. The biofilm resistance was (i) high compared to the resistance of the employed microfiltration membrane but (ii) low compared to the resistance of nanofiltration (20%) and reverse osmosis (2%) membranes. Nevertheless, biofouling is an important topic for nanofiltration and reverse osmosis membrane systems due to biofilm enhanced concentration polarization. The presence of a biofilm on the membrane surface enhances the accumulation of salts which requires increased pressure operation or causes a decreased water production rate. Biofilm accumulation, transmembrane (biofilm) resistance and feed-channel pressure drop were studied as a function of crossflow velocity (0.05 and 0.20 m s-1) and feed spacer presence at a permeate flux of 20 L m-2 h-1 (Chapter 4). As biodegradable nutrient, acetate was dosed to the feed water (0.25 and 1.0 mg L-1 carbon) to enhance biofilm accumulation in the monitors. This study showed that biofilm formation in membrane systems increased both the feed-channel and transmembrane pressure drop. The hydraulic biofilm resistance was increased by a (i) high biodegradable substrate load, (ii) high crossflow velocity, and (iii) feed spacer presence. Current membrane practice (high crossflow velocity and feed spacer presence) increased the impact of biofouling on membrane performance. The results obtained by the studies described in this thesis are discussed in Chapter 5 and suggestions for future research are given. Nutrient limitation, low flux operation, and low crossflow velocity delay the transformation from biofilm into biofouling. Concentration polarization may be increased by a lower crossflow velocity but reduced by a lower permeate flux. The nutrient load in the membrane system will be reduced by the application of low crossflow velocities. Biofouling prohibition by nutrient limitation is nothing new but still one of the most effective ways to slow down the problem. The impact of modified operation conditions and design (e.g. spacers, membrane module) on membrane performance, cleanability, and concentration polarization in full scale membrane systems should be part of future biofouling research

Role of toys in the development and rehabilitation of children with developmental disorders

Mikołajewska Emilia, Komendziński Tomasz, Dreszer Joanna, Bałaj Bibianna, Mikołajewski Dariusz. Role of toys in the development and rehabilitation of children with developmental disorders. Journal of Education, Health and Sport. 2015;5(4):224-228. ISSN 2391-8306. DOI: 10.5281/zenodo.16864http://ojs.ukw.edu.pl/index.php/johs/article/view/2015%3B5%284%29%3A224-228https://pbn.nauka.gov.pl/works/554863http://dx.doi.org/10.5281/zenodo.16864Formerly Journal of Health Sciences. ISSN 1429-9623 / 2300-665X. Archives 2011 – 2014 http://journal.rsw.edu.pl/index.php/JHS/issue/archive Deklaracja.Specyfika i zawartość merytoryczna czasopisma nie ulega zmianie.Zgodnie z informacją MNiSW z dnia 2 czerwca 2014 r., że w roku 2014 nie będzie przeprowadzana ocena czasopism naukowych; czasopismo o zmienionym tytule otrzymuje tyle samo punktów co na wykazie czasopism naukowych z dnia 31 grudnia 2014 r.The journal has had 5 points in Ministry of Science and Higher Education of Poland parametric evaluation. Part B item 1089. (31.12.2014).© The Author (s) 2015;This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland and Radom University in Radom, PolandOpen Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium,provided the original author(s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License(http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited.This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercialuse, distribution and reproduction in any medium, provided the work is properly cited.The authors declare that there is no conflict of interests regarding the publication of this paper.Received: 15.02.2015. Revised 27.03.2015. Accepted: 10.04.2015. Role of toys in the development and rehabilitation of children with developmental disorders Emilia Mikołajewska1,2,3, Tomasz Komendziński3,4, Joanna Dreszer3,4, Bibianna Bałaj3,4, Dariusz Mikołajewski3,5,6 1 Department of Physiotherapy, Ludwik Rydygier Collegium Medium in Bydgoszcz, Nicolaus Copernicus University in Toruń2 Rehabilitation Clinic, The 10th Clinical Military Hospital with Policlinic, Bydgoszcz, Poland3 Neurocognitive Laboratory, Interdisciplinary Center for Modern Technologies, Nicolaus Copernicus University in Toruń4 Department of Cognitive Science, Nicolaus Copernicus University, Toruń, Poland5 Institute of Mechanics and Applied Computer Sciences, Kazimierz Wielki Universit, Bydgoszcz, Poland6 Department of Informatics, Nicolaus Copernicus University, Toruń, Poland  Corresponding author:Emilia MikołajewskaRehabilitation ClinicMilitary Clinical Hospital No. 10 and PolyclinicBydgoszcz, Polande-mail: [email protected], [email protected]: http://emikolajewska.netstrefa.eu Keywords: rehabilitation; physiotherapy; developmental disorders; toy use; parent–child interaction; patient-therapist relationship. Abstract Developmental disorders (called also developmental disabilities) are disorders beginning before age 18 and characterized by delay of developmental skills expected to achieve in particular age or developmental stage. Every effort toward new ways of intervention is precious, and achievement of the therapeutical success still constitutes tru challenge. This study aims at assessment how toys can be incorporated into principles of the eclectic approach toward therapy of children with developmental disabilities

Role of toys in the development of healthy infants

Mikołajewska Emilia, Komendziński Tomasz, Dreszer Joanna, Bałaj Bibianna, Mikołajewski Dariusz. Role of toys in the development of healthy infants. Journal of Education, Health and Sport. 2015;5(4):219-223. ISSN 2391-8306. DOI: 10.5281/zenodo.16845http://ojs.ukw.edu.pl/index.php/johs/article/view/2015%3B5%284%29%3A219-223https://pbn.nauka.gov.pl/works/554832http://dx.doi.org/10.5281/zenodo.16845Formerly Journal of Health Sciences. ISSN 1429-9623 / 2300-665X. Archives 2011 – 2014 http://journal.rsw.edu.pl/index.php/JHS/issue/archive Deklaracja.Specyfika i zawartość merytoryczna czasopisma nie ulega zmianie.Zgodnie z informacją MNiSW z dnia 2 czerwca 2014 r., że w roku 2014 nie będzie przeprowadzana ocena czasopism naukowych; czasopismo o zmienionym tytule otrzymuje tyle samo punktów co na wykazie czasopism naukowych z dnia 31 grudnia 2014 r.The journal has had 5 points in Ministry of Science and Higher Education of Poland parametric evaluation. Part B item 1089. (31.12.2014).© The Author (s) 2015;This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland and Radom University in Radom, PolandOpen Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium,provided the original author(s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License(http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited.This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercialuse, distribution and reproduction in any medium, provided the work is properly cited.The authors declare that there is no conflict of interests regarding the publication of this paper.Received: 15.02.2015. Revised 27.03.2015. Accepted: 10.04.2015. Role of toys in the development of healthy infants Emilia Mikołajewska1,2,3, Tomasz Komendziński3,4, Joanna Dreszer3,4, Bibianna Bałaj3,4, Dariusz Mikołajewski3,5,6 1 Department of Physiotherapy, Ludwik Rydygier Collegium Medium in Bydgoszcz, Nicolaus Copernicus University in Toruń2 Rehabilitation Clinic, The 10th Clinical Military Hospital with Policlinic, Bydgoszcz, Poland3 Neurocognitive Laboratory, Interdisciplinary Center for Modern Technologies, Nicolaus Copernicus University in Toruń4 Department of Cognitive Science, Nicolaus Copernicus University, Toruń, Poland5 Institute of Mechanics and Applied Computer Sciences, Kazimierz Wielki Universit, Bydgoszcz, Poland6 Department of Informatics, Nicolaus Copernicus University, Toruń, Poland  Corresponding author:Emilia MikołajewskaRehabilitation ClinicMilitary Clinical Hospital No. 10 and PolyclinicBydgoszcz, Polande-mail: [email protected], [email protected]: http://emikolajewska.netstrefa.eu   Keywords: rehabilitation; development; gesture; toy use; parent–child interaction;   Abstract Developmental outcomes in infants can be significantly improved thanks to promising use of approapriate toys. Objective assessment of their positive influence to functional achievements in healthy infants may completely change attitude to new generation of toys, developing motor, cognitive, and social skills. Despite advances in toys assessment their true influence remains incomplete. This study aims at assessment how current knowledge and experience influences principles of the toys selection and use in healthy infants

Interactions between modified fullerenes and proteins in cancer nanotechnology

Fullerenes have numerous properties that fill the gap between small molecules and nanomaterials. Several types of chemical reaction allow their surface to be ornamented with functional groups designed to change them into ‘ideal’ nanodelivery systems. Improved stability, and bioavailability are important, but chemical modifications can render them practically soluble in water. ‘Buckyball’ fullerene scaffolds can interact with many biological targets and inhibit several proteins essential for tumorigeneses. Herein, we focus on the inhibitory properties of fullerene nanomaterials against essential proteins in cancer nanotechnology, as well as the use of dedicated proteins to improve the bioavailability of these promising nanomaterials

ToFFi - Toolbox for Frequency-based Fingerprinting of Brain Signals

Spectral fingerprints (SFs) are unique power spectra signatures of human brain regions of interest (ROIs, Keitel & Gross, 2016). SFs allow for accurate ROI identification and can serve as biomarkers of differences exhibited by non-neurotypical groups. At present, there are no open-source, versatile tools to calculate spectral fingerprints. We have filled this gap by creating a modular, highly-configurable MATLAB Toolbox for Frequency-based Fingerprinting (ToFFi). It can transform MEG/EEG signals into unique spectral representations using ROIs provided by anatomical (AAL, Desikan-Killiany), functional (Schaefer), or other custom volumetric brain parcellations. Toolbox design supports reproducibility and parallel computations.Comment: 21 pages, 10 figure

ToFFi – Toolbox for frequency-based fingerprinting of brain signals

Spectral fingerprints (SFs) are unique power spectra signatures of human brain regions of interest (ROIs, Keitel & Gross, 2016). SFs allow for accurate ROI identification and can serve as biomarkers of differences exhibited by non-neurotypical groups. At present, there are no open-source, versatile tools to calculate spectral fingerprints. We have filled this gap by creating a modular, highly-configurable MATLAB Toolbox for Frequency-based Fingerprinting (ToFFi). It can transform magnetoencephalographic and electroencephalographic signals into unique spectral representations using ROIs provided by anatomical (AAL, Desikan-Killiany), functional (Schaefer), or other custom volumetric brain parcellations. Toolbox design supports reproducibility and parallel computations

Spatiotemporal complexity patterns of resting‐state bioelectrical activity explain fluid intelligence : sex matters

Neural complexity is thought to be associated with efficient information processing but the exact nature of this relation remains unclear. Here, the relationship of fluid intelligence (gf) with the resting‐state EEG (rsEEG) complexity over different timescales and different electrodes was investigated. A 6‐min rsEEG blocks of eyes open were analyzed. The results of 119 subjects (57 men, mean age = 22.85 ± 2.84 years) were examined using multivariate multiscale sample entropy (mMSE) that quantifies changes in information richness of rsEEG in multiple data channels at fine and coarse timescales. gf factor was extracted from six intelligence tests. Partial least square regression analysis revealed that mainly predictors of the rsEEG complexity at coarse timescales in the frontoparietal network (FPN) and the temporo‐parietal complexities at fine timescales were relevant to higher gf. Sex differently affected the relationship between fluid intelligence and EEG complexity at rest. In men, gf was mainly positively related to the complexity at coarse timescales in the FPN. Furthermore, at fine and coarse timescales positive relations in the parietal region were revealed. In women, positive relations with gf were mostly observed for the overall and the coarse complexity in the FPN, whereas negative associations with gf were found for the complexity at fine timescales in the parietal and centro‐temporal region. These outcomes indicate that two separate time pathways (corresponding to fine and coarse timescales) used to characterize rsEEG complexity (expressed by mMSE features) are beneficial for effective information processing

A Model-Based Analysis of GC-Biased Gene Conversion in the Human and Chimpanzee Genomes

GC-biased gene conversion (gBGC) is a recombination-associated process that favors the fixation of G/C alleles over A/T alleles. In mammals, gBGC is hypothesized to contribute to variation in GC content, rapidly evolving sequences, and the fixation of deleterious mutations, but its prevalence and general functional consequences remain poorly understood. gBGC is difficult to incorporate into models of molecular evolution and so far has primarily been studied using summary statistics from genomic comparisons. Here, we introduce a new probabilistic model that captures the joint effects of natural selection and gBGC on nucleotide substitution patterns, while allowing for correlations along the genome in these effects. We implemented our model in a computer program, called phastBias, that can accurately detect gBGC tracts about 1 kilobase or longer in simulated sequence alignments. When applied to real primate genome sequences, phastBias predicts gBGC tracts that cover roughly 0.3% of the human and chimpanzee genomes and account for 1.2% of human-chimpanzee nucleotide differences. These tracts fall in clusters, particularly in subtelomeric regions; they are enriched for recombination hotspots and fast-evolving sequences; and they display an ongoing fixation preference for G and C alleles. They are also significantly enriched for disease-associated polymorphisms, suggesting that they contribute to the fixation of deleterious alleles. The gBGC tracts provide a unique window into historical recombination processes along the human and chimpanzee lineages. They supply additional evidence of long-term conservation of megabase-scale recombination rates accompanied by rapid turnover of hotspots. Together, these findings shed new light on the evolutionary, functional, and disease implications of gBGC. The phastBias program and our predicted tracts are freely available. © 2013 Capra et al

Forces Shaping the Fastest Evolving Regions in the Human Genome

Comparative genomics allow us to search the human genome for segments that were extensively changed in the last ~5 million years since divergence from our common ancestor with chimpanzee, but are highly conserved in other species and thus are likely to be functional. We found 202 genomic elements that are highly conserved in vertebrates but show evidence of significantly accelerated substitution rates in human. These are mostly in non-coding DNA, often near genes associated with transcription and DNA binding. Resequencing confirmed that the five most accelerated elements are dramatically changed in human but not in other primates, with seven times more substitutions in human than in chimp. The accelerated elements, and in particular the top five, show a strong bias for adenine and thymine to guanine and cytosine nucleotide changes and are disproportionately located in high recombination and high guanine and cytosine content environments near telomeres, suggesting either biased gene conversion or isochore selection. In addition, there is some evidence of directional selection in the regions containing the two most accelerated regions. A combination of evolutionary forces has contributed to accelerated evolution of the fastest evolving elements in the human genome