Biokinetic Studies Research Articles

Meta-analysis of soil and dust ingestion studies

The ingestion of soil and dust by children and adults is a potential source of exposure to environmental contaminants. To advance beyond the simple averaging of estimates used in the U.S. EPA's Exposure Factors Handbook (EFH), we describe a novel meta-analysis of all available studies that provided soil or dust ingestion estimates for children or adults conducted in the United States and Canada. Using meta-analytic techniques, we estimate the mean total soil plus dust ingestion rates and confidence intervals (CIs) for eleven age groups (0 - <1 month (m), 1 - <3 m, 3 - <6 m, 6 - <12 m, 1 - <2 years (y), 2 - <3 y, 3 - <6 y, 6 - <11 y, 11 - <16 y, 16 - <21 y, and 21+ y). These age groups were selected for consistency with the EFH update to Chapter 5 and the U.S. EPA's Age Grouping Guidance. For each age group, we calculated best estimates for the three main types of ingestion studies: tracer studies based on the aluminum tracer, biokinetic studies, and activity pattern (modeling) studies, as well as overall estimates for all three study types combined. Our meta-analysis combined study estimates using the alternative statistical approaches of the fixed effect method (inverse variance method, “I–V”) and two random effects methods, DerSimonian and Laird's method of moments (“DSL”) and the restricted maximum likelihood method (“MIXED”). For each approach, the mean total soil plus dust ingestion rate estimates for each study type generally aligned well with the EFH, ranging from 36 to 68 mg/day for infants, 56–72 mg/day for young children, and 12–32 mg/day for adolescents and adults. When all three study types were combined, the upper bounds of the 95% CI were generally the lowest for the I–V method and the highest for the MIXED method. The estimates produced here can be used for stochastic risk assessments and provide a better estimate of soil and dust ingestion rates across age groups.

68Ga-DOTA-D-Alanine-BoroPro Radiotracer for Imaging of the Fibroblast Activation Protein in Malignant and Non-Malignant Diseases.

Recently, we reported a new fibroblast activation protein (FAP) inhibitor radiopharmaceutical based on the 99mTc-((R)-1-((6-hydrazinylnicotinoyl)-D-alanyl) pyrrolidin-2-yl) boronic acid (99mTc-HYNIC-D-Alanine-BoroPro)(99mTc-HYNIC-iFAP) structure for tumor microenvironment SPECT imaging. This research aimed to synthesize 68Ga-[2,2',2″,2‴-(2-(4-(2-(5-(((S)-1-((S)-2-boronopyrrolidin-1-yl)-1-oxopropan-2-yl)carbamoyl)pyridin-2-yl)hydrazine-1-carbothioamido)benzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid] (68Ga-DOTA-D-Alanine-BoroPro)(68Ga-iFAP) as a novel radiotracer for PET imaging and evaluate its usefulness for FAP expression in malignant and non-malignant tissues. The coupling of p-SCN-benzene DOTA with HYNIC-iFAP was used for the chemical synthesis and further labeling with 68Ga. Radiochemical purity was verified by radio-HPLC. The specificity of 68Ga-iFAP was evaluated in HCT116 cells, in which FAP expression was verified by immunofluorescence and Western blot. Biodistribution and biokinetic studies were performed in murine models. 68Ga-iFAP uptake at the myocardial level was assessed in mice with induced infarction. First-in-human images of 68Ga-iFAP in healthy subjects and patients with myocardial infarction, glioblastoma, prostate cancer, and breast cancer were also obtained. DOTA-D-Alanine BoroPro was prepared with a chemical purity of 98% and was characterized by UPLC mass spectroscopy, FT-IR, and UV-vis. The 68Ga-iFAP was obtained with a radiochemical purity of >95%. In vitro and in vivo studies demonstrated 68Ga-iFAP-specific recognition for FAP, rapid renal elimination, and adequate visualization of the glioblastoma, breast tumor, prostate cancer, and myocardial infarction sites. The results of this research justify further dosimetry and clinical trials to establish the specificity and sensitivity of 68Ga-iFAP PET for FAP expression imaging.

Integrated attached and suspended biomass moving bed membrane bioreactor for municipal wastewater treatment: performance and biokinetic study

Integrated attached and suspended biomass moving bed membrane bioreactor for municipal wastewater treatment: performance and biokinetic study

Experimental validation of an innovative approach in biokinetics study for personalised dosimetry of molecular radiation therapy treatments

One of today’s main challenges in molecular radiation therapy is to assess an individual dosimetry that allows treatment to be tailored to the specific patient, in accordance with the current paradigm of ‘personalized medicine’. The evaluation of the absorbed doses for tumor and organs at risk in molecular radiotherapy is typically based on MIRD schema acquiring few experimental points for the assessement of biokinetic parameters. WIDMApp, the wearable individual dose monitoring apparatus, is an innovative approach for internal dosimetry based on a wearable radiation detecting system for individual biokinetics sampling, a Monte Carlo simulation for particle interaction, and an unfolding algorithm for data analysis and integrated activity determination at organ level. A prototype of a WIDMApp detector element was used to record the photon emissions in a body phantom containing 3 spheres with liquid sources (18F, 64Cu and 99m Tc) to simulate organs having different washout. Modelling the phantom geometry on the basis of a CT scan imaging, the Monte Carlo simulation computed the contribution of each emitting sphere to the signal detected in 3 positions on the phantoms surface. Combining the simulated results with the data acquired for 120 h, the unfolding algorithm deconvolved the detected signal and assessed the decay half-life (T 1/2) and initial activity values (A(0)) that best reproduces the observed exponential decays. A 3%–18% level of agreement is found between the actual A(0) and T 1/2 values and those obtained by means of the minimization procedure based on the Monte Carlo simulation. That resulted in an estimation of the cumulated activity <15%. Moreover, WIDMApp data redundancy has been used to mitigate some experimental occurrences that happened during data taking. A first experimental test of the WIDMApp approach to internal radiation dosimetry is presented. Studies with patients are foreseen to validate the technique in a real environment.

4-Aminobenzoic acid, 2-phenoxyethanol and iodine used as tracers in a short-term in vivo-kinetics study for tattoo ink ingredients: Mass spectrometry method development and validation

Tattoos have been gaining popularity in recent years, leading to a growing interest in researching tattoo inks and the tattooing process itself. Since the exposure to soluble tattoo ink ingredients has not yet been investigated, we here present the method validation for a short-term biokinetics study on soluble tattoo ink ingredients. The three tracers 4-aminobenzoic acid (PABA), 2-phenoxyethanol (PEtOH) and iodine will be added to commercially available tattoo inks, which will subsequently be used on healthy study participants. Following the tattooing process, blood and urine will be sampled at specific time points and analysed for these tracers. For this purpose, a method using liquid chromatography separation coupled to a quadrupole time-of-flight mass spectrometer (LC-QTOF-MS) in positive and negative ESI mode for the quantification of PABA, PEtOH and selected metabolites and an inductively-coupled plasma (ICP)-MS method for the determination of iodine were developed and validated. For LC-QTOF-MS analysis, the most applicable additives for LC eluents (0.01 % formic acid for positive and 0.005 % acetic acid for negative mode) were identified. Protein precipitation with acetonitrile was chosen for sample preparation. The methods were validated for selectivity, specificity, carryover, linearity, limit of detection (LOD) and quantification (LOQ), matrix effects, accuracy and precision, stability under different conditions and dilution integrity according to national and international guidelines with an allowed maximum variation of ±15 %. The LC-QTOF-MS method met the imposed guideline criteria for most parameters, however, some metabolites showed strong matrix effects. Validation of the ICP-MS method revealed that the KED-H2 collision mode is superior to the standard analysis mode due to enhanced method accuracy. The methods were validated for the relevant matrices plasma, urine, tattoo ink and tattoo consumables and proved to be applicable for the main target substances in the short-term biokinetics study. A proof-of-concept study showed successful quantification of iodine and PABA metabolites. The PEtOH metabolite was also quantified, but showed strong matrix effects in urine. Therefore standard addition was selected as an alternative quantification method.

Isolation of Furfuryl Alcohol Degrading Bacteria from Aromatic Compound‐Based Industrial Waste

AbstractPolyfurfuryl alcohol (PFA) is one of the thermoset biopolymers that can meet the demand of green polymers. Furfuryl alcohol (FA) is the building unit of this promising biopolymer. This work is a preliminary study of microbial degradation of FA. FA degrading bacterial strains have been isolated from sites exposed to various aromatic compounds such as industrial effluents. A total of eight bacterial isolates have been selected as potential FA degraders based on their growth, with FA as the sole carbon source, colony morphology, and biochemical characteristics. In addition, the biokinetic study of the potent bacterial isolates has been performed, and a specific growth rate evaluated.

Evolution of Portable Sensors for In-Vivo Dose and Time-Activity Curve Monitoring as Tools for Personalized Dosimetry in Molecular Radiotherapy

Treatment personalization in Molecular Radiotherapy (MRT) relies on pre- and post-treatment SPECT/ PET-based images and measurements to obtain a patient-specific absorbed dose-rate distribution map and its evolution over time. Unfortunately, the number of time points that are available per patient to investigate individual pharmacokinetics is often reduced by limited patient compliance or SPECT or PET/CT scanner availability for dosimetry in busy departments. The adoption of portable sensors for in-vivo dose monitoring during the entire treatment could improve the assessment of individual biokinetics in MRT and, thus, the treatment personalization. The evolution of portable devices, non-SPECT/PET-based options, already used for monitoring radionuclide activity transit and accumulation during therapy with radionuclides (i.e., MRT or brachytherapy), is presented to identify valuable ones, which combined with conventional nuclear medicine imaging systems could be effective in MRT. External probes, integration dosimeters and active detecting systems were included in the study. The devices and their technology, the range of applications, the features and limitations are discussed. Our overview of the available technologies encourages research and development of portable devices and dedicated algorithms for MRT patient-specific biokinetics study. This would represent a crucial advancement towards personalized treatment in MRT.

Iodine-131 radiolabeled polyvinylchloride: A potential radiotracer for micro and nanoplastics bioaccumulation and biodistribution study in organisms

The microplastics amount in the environment is significantly increasing due to human activity, and the hazards are still being investigated. To evaluate the fate of microplastics in organisms, an accurate, fast, and sensitive method is required. Nuclear technology harnessing radiotracer is one of the most sensitive and accurate method for bioaccumulation, biodistribution and biokinetic study. Here, we developed a preparation method for radioiodinated polyvinyl chloride (PVC) as a potential radiotracer of microplastics. Iodine-131 (131I) as a potential radiotracer for microplastic was used in this experiment (activity of 98.05–221.63 MBq). The 131I-PVC was prepared using the Conant-Finkelstein reaction with a solvent combination of phosphate buffer (B), acetone (A), and tetrahydrofuran (T). Such preparation method resulted in spherical 131I-PVC with sizes ranging from 608.6 to 5457.0 nm. Our study showed that acetone is the most suitable solvent for the radioiodination process, resulting in a stable 131I-PVC for up to six days.

Biokinetics and Internal Dosimetry of Tritiated Steel Particles.

Decommissioning fission and fusion facilities can result in the production of airborne particles containing tritium that could inadvertently be inhaled by workers directly involved in the operations, and potentially others, resulting in internal exposures to tritium. Of particular interest in this context, given the potentially large masses of material involved, is tritiated steel. The International Commission on Radiological Protection (ICRP) has recommended committed effective dose coefficients for inhalation of some tritiated materials, but not specifically for tritiated steel. The lack of a dose coefficient for tritiated steel is a concern given the potential importance of the material. To address this knowledge gap, a “dissolution” study, in vivo biokinetic study in a rodent model (1 MBq intratracheal instillation, 3-month follow-up) and associated state-of-the-art modelling were undertaken to derive dose coefficients for model tritiated steel particles. A committed effective dose coefficient for the inhalation of 3.3 × 10−12 Sv Bq−1 was evaluated for the particles, reflecting an activity median aerodynamic diameter (AMAD) of 13.3 µm, with the value for a reference AMAD for workers (5 µm) of 5.6 × 10−12 Sv Bq−1 that may be applied to occupational inhalation exposure to tritiated steel particles.

Biokinetic Study of Microbial Decontamination of Oilfield Produced Water

This work was aimed at identifying microbials and determining the biokinetic parameters for bio-decontamination of oilfield produced water. An extant physical treatment unit for produced water was re-engineered and retrofit with a discontinuous aerobic bioreactor (Bio-Unit) system. The Bio-Unit was operated in a fill-and-draw sequence and the rates of total organic carbon (TOC) removal and biomass growth were monitored. The isolated microbial strains were identified as Bacillus, Pseudomonas and Chryseobacterium spp. The biokinetic parameters of the bio-detoxification process were determined by fitting experimental data into the Monod Equation. The maximum specific substrate utilization rate (k_m), maximum specific growth rate (μ(m,h )), substrate half saturation coefficient (K(STOC )), yield (Y), and endogenous decay rate (b_h), were found to be 0.20 day-1, 0.31 day-1, 2.7 mg TOC/l, 1.6 mg MLSS/mg TOC, and 0.23 day-1, respectively. These values are within the range published in literatures for oilfield produced water, thus will suffice for designing, modeling and control of biological treatment systems, since biokinetic parameters for real oilfield produced water treatment using discontinuous biological configuration is scanty.

Synthesis, Characterization, and Performance Evaluation of Hybrid Waste Sludge Biochar for COD and Color Removal from Agro-Industrial Effluent

Agro-waste management processes are evolving through the development of novel experimental approaches to understand the mechanisms in reducing their pollution levels efficiently and economically from industrial effluents. Agro-industrial effluent (AIE) from biorefineries that contain high concentrations of COD and color are discharged into the ecosystem. Thus, the AIE from these biorefineries requires treatment prior to discharge. Therefore, the effectiveness of a continuous flow bioreactor system (CFBS) in the treatment of AIE using hybrid waste sludge biochar (HWSB) was investigated. The use of a bioreactor with hydraulic retention time (HRT) of 1–3 days and AIE concentrations of 10–50% was used in experiments based on a statistical design. AIE concentration and HRT were optimized using response surface methodology (RSM) as the process variables. The performance of CFBS was analyzed in terms of COD and color removal. Findings indicated 76.52% and 66.97% reduction in COD and color, respectively. During biokinetic studies, the modified Stover models were found to be perfectly suited for the observed measurements with R2 values 0.9741 attained for COD. Maximum contaminants elimination was attained at 30% AIE and 2-day HRT. Thus, this study proves that the HWSB made from biomass waste can potentially help preserve nonrenewable resources and promote zero-waste attainment and principles of circular economy.

Methods of improving brain dose estimates for internally deposited radionuclides * * This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or

The US National Council on Radiation Protection and Measurements (NCRP) convened Scientific Committee 6–12 (SC 6–12) to examine methods for improving dose estimates for brain tissue for internally deposited radionuclides, with emphasis on alpha emitters. This Memorandum summarises the main findings of SC 6–12 described in the recently published NCRP Commentary No. 31, ‘Development of Kinetic and Anatomical Models for Brain Dosimetry for Internally Deposited Radionuclides’. The Commentary examines the extent to which dose estimates for the brain could be improved through increased realism in the biokinetic and dosimetric models currently used in radiation protection and epidemiology. A limitation of most of the current element-specific systemic biokinetic models is the absence of brain as an explicitly identified source region with its unique rate(s) of exchange of the element with blood. The brain is usually included in a large source region called Other that contains all tissues not considered major repositories for the element. In effect, all tissues in Other are assigned a common set of exchange rates with blood. A limitation of current dosimetric models for internal emitters is that activity in the brain is treated as a well-mixed pool, although more sophisticated models allowing consideration of different activity concentrations in different regions of the brain have been proposed. Case studies for 18 internal emitters indicate that brain dose estimates using current dosimetric models may change substantially (by a factor of 5 or more), or may change only modestly, by addition of a sub-model of the brain in the biokinetic model, with transfer rates based on results of published biokinetic studies and autopsy data for the element of interest. As a starting place for improving brain dose estimates, development of biokinetic models with explicit sub-models of the brain (when sufficient biokinetic data are available) is underway for radionuclides frequently encountered in radiation epidemiology. A longer-term goal is development of coordinated biokinetic and dosimetric models that address the distribution of major radioelements among radiosensitive brain tissues.

Two stage treatability and biokinetic study of dairy wastewater using bacterial consortium and microalgae

Purpose of present research work is to perform nutrient removal and evaluate bio-kinetic coefficients of a two-stage dairy wastewater treatment process in batch reactor using bacterial consortium and microalgae Chlorella pyrenoidosa. The research work was performed in laboratory-scale batch reactor. Primary treated real life dairy wastewater after a treatment with a consortium of bacterial population containing carbon oxidation and nitrification bacteria was taken as the feed material for algal treatment process using microalgae C. pyrenoidosa strain. Nitrate nitrogen which was formed during bacterial nitrification still remaining in bacterial pre-treated dairy wastewater along with phosphorus that have been removed by algal treatment using microalgae of C. pyrenoidosa. The present investigation was done for bacterial and algal treatment of dairy plant effluent in a lab-scale batch reactor with acclimatized seeds of both carbon oxidation, nitrification bacteria, microalgae C. pyrenoidosa and also to evaluate various biokinetic coefficients. Around 95% ammonium nitrogen and soluble chemical oxygen demand (SCOD), around 99.67% and 90.25% of Nitrate nitrogen (NO3−-N) and Phosphorus (PO43-- P) removal were achieved corresponding to initial ammonium nitrogen and SCOD of 55 and 720 mg/L, nitrate nitrogen and phosphorus concentration of 54 and 16 mg/L respectively, with an initial inoculum concentration of bacterial consortium of 15%; corresponding to 1500 mg/L and microalgae C. pyrenoidosa of 0.8% v/v; corresponding to 80 mg/L after 24 h and 8 days of detention period in batch reactor respectively. Kinetic study was also carried out to obtain bio-kinetic coefficient for SCOD, ammonium nitrogen, nitrate nitrogen and phosphorus removal using bacterium and microalgae C. pyrenoidosa.

O1 - Temperature Impacts on Streptococcus Mutans Growth and Substrate Utilization Kinetics

Streptococcus mutans has been studied as a model cariogenic bacterium for decades. In spite of myriad studies, growth and substrate utilization kinetics studies have been largely limited to human body temperature (37 C). This makes it difficult to quantitatively assess the impact of temperature on metabolic kinetics. The objective of this study is to evaluate the effect of temperature, substrate, and nutrient conditions on S. mutans biokinetic parameters to provide comparability between biokinetic studies. S. mutans UA159 from ATCC (700610) was maintained on brain heart infusion (BHI) agar plates. S. mutans was grown in a chemostat fed BHI with either sucrose or glucose to calculate yield, maximal substrate utilization rate, endogenous decay, and half saturation constant from cellmass and substrate data assuming Monod kinetics. Pseudo-first order growth rates were determined in batch culture grown on sucrose or glucose with rich (100% BHI) and diluted (10% BHI) media at different temperatures (20-37 C). An Arrhenius plot was used to assess the impact of temperature on growth. Statistical significance was determined at the 95% confidence interval. Cell yield was statistically significantly greater on sucrose compared to glucose (0.2 g biomass/g sucrose compared to 0.1 g biomass/g glucose) at 37 C. The maximal substrate utilization rate was greater on glucose-amended media compared to sucrose. At lower temperatures, cell growth rate was statistically significantly greater on glucose compared to sucrose, but at 37 C, the growth rate was statistically significantly greater for sucrose-amended diluted media. This indicates that growth on sucrose is more strongly impacted by changes in temperature under nutrient-limited conditions, as confirmed by Arrhenius slope for S. mutans at 65 +/- 15 kJ/mol while growing on glucose and 84 +/- 20 kJ/mol on sucrose. Growth on glucose under nutrient rich conditions had the greatest Arrhenius slope of 132 +/- 8 kJ/mol. These findings enhance the understanding of S. mutans biokinetics and provide useful data for comparing studies under different environmental conditions. S. mutans has a greater cell growth yield on sucrose compared to glucose. Further, growth at lower temperatures is more strongly dependent on having rich media regardless of substrate, as growth rate was approximately double in rich media compared to either sucrose or glucose in diluted media at 20 C. At greater temperatures, these nutritional requirements were less important, as kinetic rates were only 10-20% greater when grown in rich media at human body temperature.

Technical note: A wearable radiation measurement system for collection of patient-specific time-activity data in radiopharmaceutical therapy: system design and Monte Carlo simulation results.

Purpose: A high level of personalization in Molecular Radiotherapy (MRT) could bring advantages in terms of treatment effectiveness and toxicity reduction. Individual organ‐level dosimetry is crucial to describe the radiopharmaceutical biodistribution expressed by the patient, to estimate absorbed doses to normal organs and target tissue(s). This paper presents a proof‐of‐concept Monte Carlo simulation study of “WIDMApp” (Wearable Individual Dose Monitoring Apparatus), a multi‐channel radiation detector and data processing system for in vivo patient measurement and collection of radiopharmaceutical biokinetic data (i.e., time‐activity data). Potentially, such a system can increase the amount of such data that can be collected while reducing the need to derive it via nuclear medicine imaging. Methods: a male anthropomorphic MIRD phantom was used to simulate photons (i.e., gamma‐rays) propagation in a patient undergoing a 131I thyroid treatment. The administered activity was set to the amount usually administered for the treatment of differentiated carcinoma while its initial distribution in different organs was assigned following the ICRP indications for the 131I biokinetics. Using this information, the simulation computes the Time‐dependent Counts Curves (TCCs) that would have been measured by seven WIDMApp‐like sensors placed and oriented to face each one of five emitting organs plus two thyroid lobes. A deconvolution algorithm was then applied on this simulated data set to reconstruct the Time‐Activity Curve (TAC) of each organ. Deviations of the reconstructed TACs parameters from values used to generate them were studied as a function of the deconvolution algorithm initialization parameters and assuming non‐Poisson fluctuation of the TCCs data points. Results: This study demonstrates that it is possible, at least in the simple simulated scenario, to reconstruct the organ cumulated activity by measuring the time dependence of counts recorded by several detectors placed at selected positions on the patient's body. The ability to perform in vivo sampling more frequently than conventional biokinetic studies increases the number of time points and therefore the accuracy in TAC estimates. In this study, an accuracy on cumulated activity of 5% is obtained even with a 20% error on the TCC data points and a 50% error on the initial guess on the parameters of the deconvolution algorithm. Conclusions: the WIDMApp approach could provide an effective tool to characterize more accurately the radiopharmaceutical biokinetics in MRT patients, reducing the need of resources of nuclear medicine departments, such as technologist and scanner time, to perform individualized biokinetics studies. The relatively simple hardware for the approach proposed would allow its application to large numbers of patients. The results obtained justify development of an actual prototype system to characterize this technique under realistic conditions.

Bioelectrochemical system for anaerobic oily wastewater treatment: Biokinetic & energy consumption studies

The present study introduced a laboratory-scale, anaerobic treatment system for the removal of oil from synthetic wastewater using a biofilm-electrode reactor (BER). The operating parameters of current intensity, initial concentration, reaction time, and supporting electrolyte were investigated. The results of the present study showed that the optimal conditions were: a current intensity of 15 mA, COD concentration of 1500 mg L−1, a reaction time of three days, and 150 mg L−1 NaCl as a supporting electrolyte. The highest efficiency for the COD removal was 86.7% using the introduced method, while it was 65.9% using general biological processes. In the present study, the energy consumed by the bioelectrochemical system was 1.914 kWh/m3. The biokinetic study indicated that the removal reaction was more consistent with the modified Stover-Kincannon model. The present study indicated that BER is a promising method for the treatment of oil-contaminated wastewaters. It is expected that experimental results will be used as a reference for advance bio-treating of oily wastewater.

Decolourization of Dye Wastewater by A Malaysian isolate of Aspergillus iizukae 605EAN Strain: A Biokinetic, Mechanism and Microstructure Study

ABSTRACT The current study aimed to investigate the potential of Aspergillus iizukae EAN605 for removing remazol brilliant blue R (RBBR), methyl orange (MO) and methyl red (MR) from dye-containing wastewater to provide controlled degradation pathway for the dyes in the wastewater. The removal rate and batch kinetic coefficients of the dye, as well as the microstructure of A. iizukae EAN605 mycelium during the mycoremediation process, were investigated in the Bach study. The decolourisation was due to the action of laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP). The maximum removal of RBBR was 94.78% at 10 mg/100 mL observed after 9 days. Meanwhile, the removal of MO and MR was 84.90% and 47.65% at 40 mg/100 mL observed after 3 days of experiment. The kinetic coefficients for the removal of RBBR, MO and MR by A. iizukae EAN605 were determined as = 1032.21 mg log10 cell mL–1 d–1 and = 65,637.90 mg L–1 for RBBR; = 4.64 mg log10 cell mL–1 d–1 and = 460.16 mg L–1 for MO; and = 0.576 mg log10 cell mL–1 d–1 and = 228.82 mg L–1 for MR. The Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (FESEM-EDX), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and Raman Spectroscopy analysis confirmed that the biosorption of dyes destroyed the mycelium surface and changed its functional groups structure. The findings have revealed that the high potential of A. iizukae EAN605 in dyes decolourisation.

Temperature and oxygen level determine N2 O respiration activities of heterotrophic N2 O-reducing bacteria: Biokinetic study.

Nitrous oxide (N2 O), a potent greenhouse gas, is reduced to N2 gas by N2 O-reducing bacteria (N2 ORB), a process which represents an N2 O sink in natural and engineered ecosystems. The N2 O sink activity by N2 ORB depends on temperature and O2 exposure, yet the specifics are not yet understood. This study explores the effects of temperature and oxygen exposure on biokinetics of pure culture N2 ORB. Four N2 ORB, representing either clade I type nosZ (Pseudomonas stutzeri JCM5965 and Paracoccus denitrificans NBRC102528) or clade II type nosZ (Azospira sp. strains I09 and I13), were individually tested. The higher activation energy for N2 O by Azospira sp. strain I13 (114.0 ± 22.6 kJ mol-1 ) compared with the other tested N2 ORB (38.3-60.1 kJ mol-1 ) indicates that N2 ORB can adapt to different temperatures. The O2 inhibition constants (KI ) of Azospira sp. strain I09 and Ps. stutzeri JCM5965 increased from 0.06 ± 0.05 and 0.05 ± 0.02 μmol L-1 to 0.92 ± 0.24 and 0.84 ± 0.31 μmol L-1 , respectively, as the temperature increased from 15°C to 35°C, while that of Azospira sp. strain I13 was temperature-independent (p = 0.106). Within the range of temperatures examined, Azospira sp. strain I13 had a faster recovery after O2 exposure compared with Azospira sp. strain I09 and Ps. stutzeri JCM5965 (p < 0.05). These results suggest that temperature and O2 exposure result in the growth of ecophysiologically distinct N2 ORB as N2 O sinks. This knowledge can help develop a suitable N2 O mitigation strategy according to the physiologies of the predominant N2 ORB.

Internal dose assessment of 148Gd using isotope ratios of gamma-emitting 146Gd or 153Gd in accidently released spallation target particles

The pure alpha emitter 148Gd may have a significant radiological impact in terms of internal dose to exposed humans in case of accidental releases from a spallation source using a tungsten target, such as the one to be used in the European Spallation Source (ESS). In this work we aim to present an approach to indirectly estimate the whole-body burden of 148Gd and the associated committed effective dose in exposed humans, by means of high-resolution gamma spectrometry of the gamma-emitting radiogadolinium isotopes 146Gd and 153Gd that are accompanied by 148Gd generated from the operation of the tungsten target. Theoretical minimum detectable whole-body activity (MDA) and associated internal doses from 148Gd are calculated using a combination of existing biokinetic models and recent computer simulation studies on the generated isotope ratios of 146Gd/148Gd and 153Gd/148Gd in the ESS target. Of the two gamma-emitting gadolinium isotopes, 146Gd is initially the most sensitive indicator of the presence of 148Gd if whole-body counting is performed within a month after the release, using the twin photo peaks of 146Gd centered at 115.4 keV (MDA < 1 Bq for ingested 148Gd, and < 25 Bq for inhaled 148Gd). The corresponding minimum detectable committed effective doses will be less than 1 µSv for ingested 148Gd, but substantially higher for inhaled 148Gd (up to 0.3 mSv), depending on operation time of the target prior to the release. However, a few months after an atmospheric release, 153Gd becomes a much more sensitive indicator of body burdens of 148Gd, with a minimum detectable committed effective doses ranging from 18 to 77 µSv for chronic ingestion and between 0.65 to 2.7 mSv for acute inhalation in connection to the release. The main issue with this indirect method for 148Gd internal dose estimation, is whether the primary photon peaks from 146 and 153Gd can be detected undisturbed. Preliminary simulations show that nuclides such as 182Ta may potentially create perturbations that could impair this evaluation method, and which impact needs to be further studied in future safety assessments of accidental target releases.

Characterisation of a hand-held CZT-based gamma camera for 177Lu imaging

BackgroundCurrently, hand-held gamma cameras are being developed for 99mTc imaging, mainly for sentinel lymph node detection. These cameras offer advantages, such as mobility and ease of access, and may be useful also for other applications such as biokinetic studies in animals or for imaging of small, superficial structures in patients. In this work, the suitability of a CZT-based hand-held camera for 177Lu imaging is investigated. The energy response of CZT-based detectors combined with the multiple photon emissions of 177Lu poses new challenges compared to 99mTc imaging, and a thorough camera characterisation is thus warranted.MethodsThree collimators (LEHR, LEHS, and MEGP) and three energy windows (55 keV, 113 keV, and 208 keV) are investigated. Characterised camera properties include the system spatial resolution, energy resolution, sensitivity, image uniformity, septal penetration, and temperature dependence. Characterisations are made starting from NEMA guidelines when applicable, with adjustments made when required. The applicability of the camera is demonstrated by imaging of a superficially located tumour in a patient undergoing [177 Lu]Lu-DOTA-TATE therapy.ResultsOverall, the results are encouraging. Compared to a conventional gamma camera, the hand-held camera generally has a higher sensitivity for a given collimator. For source-collimator distances below 3 cm, the spatial resolution FWHM is within 6 mm for the LEHR and MEGP collimators. Before uniformity correction, the central field-of-view integral uniformity shows best results for the 113-keV window, with values obtained between 11 and 14%. The corresponding values after uniformity correction are within 3%. Effects of septal penetration are observed but are manageable with a proper combination of collimator and energy window setting. Septal penetration and collimator scatter not only affect the 208-keV window but also contribute with counts in lower windows due to energy-tailing effects. The patient study revealed non-uniform uptake patterns in a region that appeared uniform in a conventional gamma camera image.ConclusionsThe results show that the hand-held camera can be used for 177Lu imaging. A 113-keV energy window combined with LEHR or MEGP collimators provides the best image system characteristics.