Coronary artery disease severity and risk stratification of patients with non ST-elevation acute coronary syndrome using CHA2DS2-VASc-HSF score.

BACKGROUND: Risk stratification assessment of patients with non-ST elevation acute coronary syndrome (NSTE ACS) plays an important role in optimal management and defines the patient's prognosis. This study aimed to evaluate the ability of CHA2DS2-VASc-HSF score (comprising of the components of the CHA2DS2-VASc score with a male instead of female sex category, hyperlipidemia, smoking, and family history of coronary artery disease respectively) to predict the severity and complexity of CAD and its efficacy in stratification for major adverse cardiovascular events (MACE) in patients with NSTE ACS without known atrial fibrillation. METHODS: This study included 200 patients (males 72.5%, mean age 55.8 ± 10.1 years) who were admitted with NSTE ACS. CHA2DS2-VASC-HSF score was calculated on admission. Patients were classified into three groups according to their CHA2DS2-VASC-HSF score: low score group (< 2; 29 patients), intermediate score group (2-4; 83 patients), and high score group (≥ 5; 88 patients). Coronary angiography was conducted and the Syntax score (SS) was calculated. Clinical follow-up at 6 months of admission for the development of MACE was recorded. RESULTS: SS was significantly high in the high CHA2DS2-VASc-HSF score group compared with low and intermediate score groups. CHA2DS2-VASc-HSF score had a significant positive strong correlation with syntax score (r = 0.64, P < 0.001). Smoking, vascular disease, hyperlipidemia, and CHA2DS2-VASc-HSF score were independent predictors of high SS. For the prediction of severe and complex CAD, CHA2DS2-VASc-HSF score had a good predictive power at a cut-off value ≥ 5 with a sensitivity of 86% and specificity of 65%. Hypertension, vascular disease, high SS, and CHA2DS2-VASc-HSF score were independent predictors of MACE. CHA2DS2-VASC-HSF score ≥ 4 was identified as an effective cut-off point for the development of MACE with 94% sensitivity and 70% specificity. CONCLUSIONS: CHA2DS2-VASC-HSF score is proposed to be a simple bedside score that could be used for the prediction of the severity and complexity of CAD as well as a risk stratification tool for the development of MACE in NSTE ACS patients.

Removal of organic micropollutants in biologically active filters: A systematic quantitative review of key influencing factors.

Biofiltration utilizes natural mechanisms including biodegradation and biotransformation along with other physical processes for the removal of organic micropollutants (OMPs) such as pharmaceuticals, personal care products, pesticides and industrial compounds found in (waste)water. In this systematic review, a total of 120 biofiltration studies from 25 countries were analyzed, considering various biofilter configurations, source water types, biofilter media and scales of operation. The study also provides a bibliometric analysis to identify the emerging research trends in the field. The results show that granular activated carbon (GAC) either alone or in combination with another biofiltration media can remove a broad range of OMPs efficiently. The impact of pre-oxidation on biofilter performance was investigated, revealing that pre-oxidation significantly improved OMP removal and reduced the empty bed contact time (EBCT) needed to achieve a consistently high OMP. Biofiltration with pre-oxidation had median removals ranging between 65% and >90% for various OMPs at 10-45 min EBCT with data variability drastically reducing beyond 20 min EBCT. Biofiltration without pre-oxidation had lower median removals with greater variability. The results demonstrate that pre-oxidation greatly enhances the removal of adsorptive and poorly biodegradable OMPs, while its impact on other OMPs varies. Only 19% of studies we reviewed included toxicity testing of treated effluent, and even fewer measured transformation products. Several studies have previously reported an increase in effluent toxicity because of oxidation, although it was successfully abated by subsequent biofiltration in most cases. Therefore, the efficacy of biofiltration treatment should be assessed by integrating toxicity testing into the assessment of overall removal.

Seawater biodesalination treatment using Phormidium keutzingianum in attached growth-packed bed continuous flow stirred tank reactor.

Water scarcity is increasing worldwide due to rising population which is creating opportunities to unlock alternative green desalination techniques for seawater, such as biodesalination. Therefore, this study presents the utilization of the Phormidium keutzingianum strain in an attached growth-packed bed reactor to treat seawater in real-time in a continuous-flow stirred tank reactor for biodesalination. Two reactors were designed and developed, in which zeolites were used as the support media for the attached growth. The experiment was conducted in an open outdoor environment with a continuous air flow rate of 3 mL/min and two hydraulic retention times (HRT) of 7 and 15 d. Parameters such as the pH, chloride ion concentration, total organic carbon (TOC), and optical density were monitored regularly. The pH change was not significant in either reactor and remained within the range of 7.25-8.0. Chloride ion removal was the most crucial component of biodesalination efficiency, with d 7 removal efficiencies of approximately 40% and 32% for reactors 1 and 2, respectively. Reactor 1 exhibited a TOC reduction of 36% within the first 10 d at a HRT of 7, and when the HRT was set to 15 d, a TOC removal efficiency of 89% was achieved on d 53. For reactor 2, a TOC removal efficiency of approximately 81% was achieved on d 11 at HRT 7, and it reduced to less than 50% at an HRT of 15. The chloride ion and TOC removal phenomena were similar in both reactors. The optical density (OD) showed low measurement recordings, ranging from 0.005 to 0.01, indicating low cell detachment in the seawater effluent. Therefore, using the attached growth method for the biodesalination of seawater is feasible. Furthermore, biomass harvesting in attached growth systems is easier than that in suspension growth systems.

Determinants of parental seasonal influenza vaccine hesitancy in the Eastern Mediterranean region: A cross-sectional study.

Background: Seasonal influenza vaccine can reduce the risk of influenza-associated hospitalizations and deaths among children. Given that parents are the primary decision makers, this study examined the parental attitude toward childhood influenza vaccine and identified determinants of vaccine hesitancy (VH) in the Eastern Mediterranean region (EMR). Methods: A cross-sectional study was conducted using an anonymous online survey in 14 EMR countries. Parents of children aged 6 months to 18 years were included. The Parent Attitude about Childhood Vaccines (PACV) was used to assess VH. Chi square test and independent t-test were used to test for association of qualitative and quantitative variables, respectively. A structural equations model (SEM) was used to identify direct and indirect determinants of parental VH. Results: Almost half of the parents were hesitant about vaccinating their children against influenza (50.8%). Parental VH was significantly higher among older mothers (37.06 ± 8.8 years, p = 0.006), rural residents (53.6%, p < 0.001), high-income countries residents (50.6%, p < 0.001), and mothers with higher educational levels (52.1%, p < 0.001). Parents of school-aged children (5-9 years) (55.6%, p < 0.001), children free from any comorbidities (52.5%, p < 0.001), children who did not receive routine vaccination at all (51.5%, p = 0.03), children who were not vaccinated against COVID-19 (54.3%, p < 0.001), in addition to parents who were not vaccinated against influenza (57.1%, p < 0.001) were significantly associated with increased likelihood of VH. Parents who were depending on healthcare provider as a source of information regarding vaccines were less likely to report VH (47.9%, p < 0.001), meanwhile those who used social media as their source of health information showed a significantly higher VH (57.2%, p < 0.001). The SEM suggested that mother's age, residence, country income level, child gender, total number of children and source of information regarding vaccines had a direct effect on VH. Meanwhile, parents vaccinated against influenza, children completely or partially vaccinated with routine vaccines and children vaccinated against Coronavirus disease 2019 (COVID-19) had an indirect effect on VH. Conclusion: A high proportion of included parents were hesitant to vaccinate their children against seasonal influenza. This attitude is due to many modifiable and non-modifiable factors that can be targeted to improve vaccination coverage.

Natural inhibitors for acetylcholinesterase and autophagy modulators as effective antagonists for tau and ß-amyloid in Alzheimer's rat model.

Background: Phytochemicals have amazing biological effects in relation to age-related illnesses and are increasingly being studied in clinical trials. The goal of this study was to examine the effectiveness of the aqueous extracts of Rosmarinus officinalis L. (Rosemary) and Crocus sativus L. (Saffron) and their combinations as tau and ß-amyloid antagonists in an Alzheimer's rat model. Methods: AlCl3 and D-galactose (150 & 300 mg/kg) were used to create the Alzheimer's neuroinflammation rat model. The animals were subsequently given the two extracts and their combinations (500 mg/kg) along 15 days. The cognitive impairment, oxidative stress, tau & amyloid neuroproteins, acetylcholine, acetylcholinesterase neurotransmitters, proinflammatory cytokines, LC3 as an autophagy marker, computational analysis, and morphological alterations were all assessed. Results: When compared to the conventional donepezil and normal groups, the treated groups showed a significant improvement in all calculated parameters. The cortex and hippocampus have a better morphological appearance. In silico analysis found that these extracts may have an affinity for and impede the activity of some proteins thought to be essential regulators of disease progression. Conclusion: Rosemary and Saffron extracts by the power of their constituents were able to alleviate the neurotoxicity of AlCl3 & D-galactose and regulate the natural autophagy process.

Photo fermentative biohydrogen production potential using microalgae-activated sludge co-digestion in a sequential flow batch reactor (SFBR).

Biohydrogen (bioH2) is a sustainable energy source that can produce carbon-free energy upon combustion. BioH2 can be generated from microalgae by photolytic and anaerobic digestion (AD) pathways. The AD pathway faces many challenges when scaling up using different bioreactors, particularly the continuous stirred tank reactor (CSTR) and sequential flow batch reactor (SFBR). Therefore, the performance characteristics of SFBR were analysed in this study using Chlorella vulgaris and domestic wastewater activated sludge (WWAS) co-culture. An organic loading rate (OLR) of 4.7 g COD L-1 day-1 was fed to the SFBR with a hydraulic retention time (HRT) of five days in the presence of light under anaerobic conditions. The pH of the medium was maintained at 6 using a pH controller for the incubation period of 15 days. The maximum bioH2 concentrations of 421.1 µmol L-1 and 56.6 µmol L-1 were observed in the exponential and steady-state phases, respectively. The effluent had an unusually high amount of acetate of 16.6 g L-1, which remained high with an average of 11.9 g L-1 during the steady state phase. The amount of bioH2 produced was found to be inadequate but consistent when operating the SFBR with a constant OLR. Because of the limitations in CSTR handling, operating a SFBR by optimizing OLR and HRT might be more feasible in operation for bioH2 yield in upscaling. A logistic function model was also found to be the best fit for the experimental data for the prediction of bioH2 generation using co-culture in the SFBR.

Biodesalination using halophytic cyanobacterium Phormidium keutzingianum from brackish to the hypersaline water.

The biodesalination potential at different levels of salinity of Phormidium keutzingianum (P. keutzingianum) was investigated. A wide range of salinity from brackish to hypersaline water was explored in this study to ensure the adaptability of P. keutzingianum in extreme stress conditions. Brackish to hypersaline salt solutions were tested at selected NaCl concentrations 10, 30, 50, and 70 g.L-1. Chloride, pH, nitrate, and phosphate were the main parameters measured throughout the duration of the experiment. Biomass growth estimation revealed that the studied strain is adaptable to all the salinities inoculated. During the first growth phase (till day 20), chloride ion was removed up to 43.52% and 45.69% in 10 and 30 g.L-1 of salinity, respectively. Fourier transform infrared spectrometry analysis performed on P. keutzingianum showed the presence of active functional groups at all salinity levels, which resulted in biosorption leading to the bioaccumulation process. Samples for scanning electron microscopy (SEM) analysis supported with electron dispersive X-ray spectroscopy analysis (EDS) showed NaCl on samples already on day 0. This ensures the occurrence of the biosorption process. SEM-EDS results on 10th d showed evidence of additional ions deposited on the outer surface of P. keutzingianum. Calcium, magnesium, potassium, sodium, chloride, phosphorus, and iron were indicated in SEM-EDS analysis proving the occurrence of the biomineralization process. These findings confirmed that P. keutzingianum showed biomass production, biosorption, bioaccumulation, and biomineralization in all salinities; hence, the strain affirms the biodesalination process.

Removal of a mixture of formaldehyde and methanol vapors in biotrickling filters under mesophilic and thermophilic conditions: Potential application in ethanol production.

Ethanol is a significant source of energy as a biofuel; however, its production using corn involves the generation of harmful emissions from both fermentation tanks and dryers. Scrubbers control the emissions from fermentation tanks, while the emissions from the dryers are controlled by regenerative thermal oxidizers. Potential alternatives to these energy- and water-intensive technologies are biotrickling filters (BTFs). In this study, two BTFs were operated in parallel to treat formaldehyde and methanol emissions in a volumetric ratio of 4:1, one at 25°C (mesophilic), and the other at 60°C (thermophilic). The mesophilic BTF simulated emissions from fermentation tanks, while the thermophilic BTF simulated emissions from dryers. Both beds were operated at an empty bed residence time of ~30 s and influent formaldehyde concentrations of 20, 50, and 100 parts per million per volume (ppmv). Formaldehyde polymerization was reduced in this study by adding NaOH to pH levels of 7.0-7.4 and heating the solution to a temperature of 60°C. BTFs have successfully removed formaldehyde at typical ethanol plants emissions ~21 ppmv. The BTF technology have the potential in replacing the conventional air treatment methods used at ethanol plants.Implications: Currently, ethanol plants remove and treat hazardous air pollutants (HAPs) using wet scrubbers from the fermenter off-gasses and using thermal oxidizers to combust off-gasses. The utilization of biotrickling filters (BTFs) for HAP removal generally and formaldehyde particularly has wide implication in the field of renewable energy. Utilizing BTFs in the 200+ ethanol plants in USA will save cost and reduce water and energy needs significantly. BTFs can reduce an ethanol plant's carbon intensity (CI) by 1 to 3 g CO2/MJ. This can result in roughly $50 million per year in additional revenue in Nebraska for instance.

An artificial neural network combined with response surface methodology approach for modelling and optimization of the electro-coagulation for cationic dye.

An artificial neural network (ANN) approach with response surface methodology (RSM) technique has been applied to model and optimize the removal process of Brilliant Green dye by batch electrocoagulation process. A multilayer perceptron (MLP) - ANN model has been trained by four input neurons which represent the reaction time, current density, pH, NaCl concentration, and two output neurons representing the dye removal efficiency (%) and electrical energy consumption (kWh/kg). The optimized hidden layer neurons were obtained based on a minimum mean squared error. The batch electrocoagulation process was optimized using central composite design with RSM once the ANN network was trained and primed to anticipate the output. At optimized condition (electrolysis time 10 min, current density 80 A/m2, initial pH 5 and electrolyte NaCl concentration 0.5 g/L), RSM projected decolorization of 98.83% and electrical energy consumption of 14.99 kWh/kg. This study shows that the removal of brilliant green dye can be successfully carried out by a batch electrocoagulation process. Therefore, the process is successfully trained by ANN and optimized by RSM for similar applications.

Unprecedented biodesalination rates-Shortcomings of electrical conductivity measurements in determining salt removal by algae and cyanobacteria.

Phormidium keutzingianum performed biodesalination of brackish water (10 g/L). The electrical conductivity (EC) was measured to evaluate the salt concentration over 80 days of cyanobacterial inoculation. Anion concentrations were measured using ion chromatography to estimate salt removal. EC-based measurements showed ∼8-10% removal efficiency in the first 20 days. However, the removal efficiency based on chloride ion concentration showed ∼40% removal in the same time frame. The pH increase was observed with growth of algal biomass. The increasing pH proposes the formation of hydroxyl and carbonate ions. Sulfuric acid was added at day 110 to neutralize them. At pH 4, the EC reduced significantly to about ∼37% confirming the chloride removal. EC should not be used to measure salt reduction as it is an obscure parameter, and therefore, EC is not the best choice to measure salinity removal using algae. Some recently published studies used only EC to estimate biodesalination, and it is anticipated that salt removal is misrepresented in those studies.

Compliance with hand sanitizer quality during the SARS-CoV-2 pandemic: Assessing the impurities in an ethanol plant.

Using alcohol-based disinfectants is an effective method for preventing the spread of COVID-19. However, non-traditional manufacturers of alcohol-based disinfectants, such as ethanol plants, need to undergo additional treatment to curb their impurities to limits set by the Food and Drug Association (FDA) to produce alcohol-based disinfectants. To transform them to disinfectant-grade alcohol, 17 process streams in a dry-mill ethanol plant were analyzed to determine the quality parameters for acetaldehyde, acetal, propanol, methanol, and water, including chemical oxygen demand, total suspended solids, and nutrients. Results suggest that the process stream generated by the distillation column requires further treatment because the acetaldehyde and acetal concentrations are significantly higher than the impurity limit set by the FDA. The addition of a second distillation column could be a potential method for addressing impurities and it will have minimal influence on hazardous air pollutant generation and water use.

Immobilized algae-based treatment of herbicide-contaminated groundwater.

Scenedesmus species, immobilized on alginate gel, was found effective in removing nitrate, atrazine, magnesium, phosphorus, zinc, oxadiazon, and triallate from groundwater in a continuous flow reactor. The laboratory-scale experiments with synthetic groundwater, made of 8.8 mg/L NO3 -N and 90 µg/L atrazine, were performed at a hydraulic retention time of 7 days and the temperatures of 20 and 35°C. The highest uptake of nitrate and atrazine was observed at 20°C (97% and 70%, respectively). When tested in actual groundwater, 92% of nitrate, 100% of magnesium, 99.9% of phosphorus, and 92% of zinc were successfully removed at the end of 29 days' treatment operations. The algal beads removed 100% of oxadiazon and triallate in the first 10 days, but some of the herbicides diffused back into the solution toward the end of the treatment process. PRACTITIONER POINTS: Immobilized algae-alginate beads can remove nitrate, atrazine, oxadiazon, and triallate from groundwater in continuous flow reactor. The uptake rate of nitrate and atrazine is higher in room temperature (20°C). Same algae beads could be reused for herbicide uptake for the average of 10 days. The immobilized system is a natural sustainable alternative that can be used in groundwater pump and treat.

Wastewater surveillance for SARS-CoV-2: Lessons learnt from recent studies to define future applications.

Wastewater-based epidemiology (WBE) is successful in the detection of the spread of SARS-CoV-2. This review examines the methods used and results of recent studies on the quantification of SARS-CoV-2 in wastewater. WBE becomes essential, especially with virus transmission path uncertainty, limitations on the number of clinical tests that could be conducted, and a relatively long period for infected people to show symptoms. Wastewater surveillance was used to show the effect of lockdown on the virus spread. A WBE framework tailored for SARS-CoV-2 that incorporates lessons learnt from the reviewed studies was developed. Results of the review helped outline challenges facing the detection of SARS-CoV-2 in wastewater samples. A comparison between the various studies with regards to sample concentration and virus quantification was conducted. Five different primers sets were used for qPCR quantification; however, due to limited data availability, there is no consensus on the most sensitive primer. Correlating the slope of the relationship between the number of gene copies vs. the cumulative number of infections normalized to the total population served with the average new cases, suggests that qPCR results could help estimating the number of new infections. The correlation is improved when a lag period was introduced to account for asymptomatic infections. Based on lessons learnt from recent studies, it is recommended that future applications should consider the following: 1) ensuring occupational safety in managing sewage collection and processing, 2) evaluating the effectiveness of greywater disinfection, 3) measuring viral RNA decay due to biological and chemical activities during collection and treatment, 4) assessing the effectiveness of digital PCR, and 5) conducting large scale international studies that follow standardized protocols.

Integration of sodium hypochlorite pretreatment with co-immobilized microalgae/bacteria treatment of meat processing wastewater.

Wastewater with 0.2, 0.4, 0.8, 1.0 mg/L free chlorine was biologically treated using co-immobilized microalgae/bacteria. In contrast, non-pretreated wastewater was treated with beads (control) and blank beads (blank) under the same operating condition. Results showed that NaClO pretreatment removed 8-33% total nitrogen (TN), 31-45% true color and 0.7-2.5 log CFU/mL aerobic-bacteria. At the end of treatment, maximum algal biomass (2,027 dry weight mg/L) was achieved with 0.2 mg/L free chlorine. Bacterial growth in wastewater was decreased by NaClO pretreatment before reaching 7.2-7.7 log CFU/mL on the fifth day. Beads with microorganisms (control) removed 15% more chemical-oxygen-demand (COD), 16% more TN, and 13% more total phosphate (PO43-) than blank. Pretreatment with 0.2 mg/L free chlorine increased TN removal from 75% to 80% while pollutants removal was substantially decreased with 0.4-1.0 mg/L free chlorine. Considering algal biomass growth and pollutants removal, 0.2 mg/L free chlorine pretreatment was recommended for microalgae/bacteria co-immobilized system.

Heart Rate Variability as A Predictor of Hypotension Following Spinal Anesthesia for Elective Caesarian Section in Preeclamptic Parturients: A Descriptive Observational Study.

AIM: In this study we aimed to find out the heart rate variability measuring using electrical cardiometry is not reliable as a predictor for hypotension following spinal anesthesia in preeclamptic parturients undergoing elective cesarean section. METHODS: Electrical Cardiometry system was used to measure Heart rate variability (HRV) at five different time points before fluid loading (T0, baseline), after fluid loading (T1), 5 min after spinal anaesthesia (T2), 15 min after spinal anaesthesia (T3) and 30 min after spinal anaesthesia (T4). Traditional HRV measurement was determined using time-domain analysis. This Observational descriptive cohort study was conducted in Kasr Al-Ainy Hospital, Faculty of Medicine, Cairo University from February 2018 till June 2019, after approval of the Ethical Committee and written patients consent. RESULTS: The main finding of the current study is that heart rate variability measuring using electrical cardiometry is not reliable as a predictor for hypotension following spinal anaesthesia in preeclamptic parturients undergoing elective cesarean section. CONCLUSION: Heart rate variability cannot be used as a predictor for hypotension following spinal anaesthesia in preeclamptic patients undergoing elective caesarean section using electrical cardiometry.

Effects of source and seasonal variations of natural organic matters on the fate and transport of CeO2 nanoparticles in the environment.

Natural organic matter (NOM) affects the stability and transport of nanoparticles (NPs) in natural waters by modifying their physiochemical properties. Source location, and seasonal variations, influence their molecular, physical and electrical charge properties. To understand the variations of NOM on the mobilization of NPs, large volumes of water were collected from the Ohio River (OR) over winter and summer seasons and dissolved NOMs were concentrated. The chemical and structural differences of these NOMs were compared with the Suwannee River humic acid (SRHA) SRHA using 1H and 13C nuclear magnetic resonance spectroscopy, and Fourier transforms infrared (FTIR) spectroscopy. Thermal analysis and FTIR confirmed that differences in composition, structure, and functional groups are a result of SRHA fractionation compared to whole molecule OR-NOM. The influence of OR-NOMs on the surface charge of CeO2 NPs and the effects on the transport and retention in a three-phase (deposition-rinse-re-entrainment) sand-packed columns were investigated at CeO2 NPs initial concertation of 10ppm, pH6.8, increasing ionic strength (3, 5, and 10mM), retention time of 1min, and increasing NOM concentration (1, 5, and 10ppm). The summer OR-NOM showed higher stabilization and mobilization effect on the CeO2 than the winter NOM; while their effect was very different form the SRHA. The stabilization of NPs is attributed to both electrostatic and steric effects. The differences in the chemical structure of the complex and heterogeneous NOMs showed disparate reactivity and direct impact on CeO2-NPs stability. Using SRHA to study the effect of NOM for drinking water related assessment does not sufficiently represent the natural conditions of the environment.

Comparison Between Sublingual and Vaginal Administration of Misoprostol in Management of Missed Abortion.

AIM: The aim of the present study is to compare between sublingual administration of misoprostol and vaginal administration in the management of missed abortion. MATERIALS AND METHODS: The study was conducted in El-Shatby Maternity Hospital on 160 patients diagnosed as missed abortion by ultrasonographic examination. Cases were divided into two groups according to the methods of misoprostol administration, whether sublingual or vaginal. Patients of the two groups were observed for the times of uterine colic starting, cervical dilation, and conceptus expulsion, along with recording of any side effects. RESULT: During the follow-up of our cases we found that sublingual route is more effective than vaginal route in the management of missed abortion. The difference between the two groups in percentage of conceptus expulsion was statistically significant. The most common side effects were nausea which was present in 55 % of cases in group I (sublingual) and in 40 % of cases in group II (vaginal) then severe pain in 25 % of cases in group I (sublingual) and in 20 % of cases in group II (vaginal) and hyperpyrexia in 15 % of cases in group I (sublingual) and in 5 % of cases in group II (vaginal). CONCLUSION: Sublingual administration of misoprostol is more effective than its vaginal administration in missed abortion management. Side effect of misoprostol as nausea, vomiting, fever is more common with sublingual administration in comparison with its vaginal administration.

Experimental and modeling studies of sorption of ceria nanoparticle on microbial biofilms.

This study focuses on the interaction of ceria nanoparticles (CeO2-NPs) with Pseudomonas fluorescens and Mycobacterium smegmatis biofilms. Confocal laser microscopy and transmission electron microscopy determined the distribution of NPs in the complex structures of biofilm at molecular levels. Visual data showed that most of the adsorption takes place on the bacterial cell walls and spores. The interaction of nanoparticles (NPs) with biofilms reached equilibrium after the initial high adsorption rate regardless of biofilm heterogeneity and different nanoparticle concentrations in the bulk liquid. Physical processes may dominate this sorption phenomenon. Pseudo first order sorption kinetics was used to estimate adsorption and desorption rate of CeO2-NPs onto biofilms. When biofilms got exposed to CeO2-NPs, a self-protecting mechanism was observed. Cells moved away from the bulk solution in the biofilm matrix, and portions of biofilm outer layer were detached, hence releasing some CeO2-NPs back to the bulk phase.