Compartmental Systems Research Articles

Hot cell renovation in the spent fuel conditioning process facility at the Korea Atomic Energy Research Institute

Abstract Background The advanced spent fuel conditioning process facility (ACPF) of the irradiated materials examination facility (IMEF) at the Korea Atomic Energy Research Institute (KAERI) has been renovated to implement a lab scale electrolytic reduction process for pyroprocessing. The interior and exterior structures of the ACPF hot cell have been modified under the current renovation project for the experimentation of the electrolytic reduction process using spent nuclear fuel. The most important aspect of this renovation was the installation of the argon compartment within the hot cell. Method For the design and system implementation of the argon compartment system, a full-scale mock-up test and a three-dimensional (3D) simulation test were conducted in advance. The remodeling and repairing of the process cell (M8a), the maintenance cell (M8b), the isolation room, and their utilities were also planned through this simulation to accommodate the designed argon compartment system. Results and conclusion Based on the considered refurbishment workflow, previous equipment in the M8 cell, including vessels and pipes, were removed and disposed of successfully after a zoning smear survey and decontamination, and new equipment with advanced functions and specifications were installed in the hot cell. Finally, the operating area and isolation room were also refurbished to meet the requirements of the improved hot cell facility.

Indigenous arbuscular mycorrhizal (AM) fungi contribute to wheat phosphate uptake in a semi-arid field environment, shown by tracking with radioactive phosphorus

The aim was to determine the quantitative contribution of naturally-occurring arbuscular mycorrhizal (AM) fungi to phosphorus (P) uptake by wheat in the field in a semi-arid, agricultural environment. Findings were compared with a pot experiment in the same soil in order to assess the predictive value of pot experiments. Similar compartmented systems were used in both experiments, to provide radioactive P only to the AM fungal assemblage. Delivery of P to the plants was tracked and the contributions of the AM uptake pathway quantified. AM colonisation from the soil in both experiments was low and variable. A range of colonisation morphologies indicated the presence of several different AM fungi. By 44 d (pot experiment) and 67 d (field experiment) the AM pathway delivered P to all 10 plants in pots and 115/120 plants in the field. The contributions were 3–40% of total P to whole plants in pots and 6.5–21% to shoots in the field, equivalent to means of approximately 0.48 and 0.16kgPha−1, respectively (minimum estimates, see text). There was no significant relationship between % root length colonised and amount of P delivered via the AM pathway in either experiment. Even with low AM colonisation, the natural assemblage of indigenous AM fungi made a significant contribution to P uptake by wheat, a plant that is often regarded not to benefit from AM colonisation. We conclude that it is feasible to use compartmented systems in the field to estimate the quantitative contribution of AM fungi to P uptake by plants and that it is unwise to ignore the AM contribution in research aimed to understand mechanisms potentially contributing to P uptake efficiency.

Distributed Coordination for Connectivity Adjustment of Linear Compartmental Systems

This technical note studies a set-point regulation problem of linear compartmental systems given fixed external inputs. We solve this problem by controlling the flow rate in connections from one compartment to another compartment or to environment. For each connection channel, a distributed coordination rule adjusts its flow rate in order to achieve the set-point regulation. As a novel approach, the coordination rule requires only information of neighbor compartments; thus, it can be implemented by using only local interaction information.

Microbial fuel cells continuously fuelled by untreated fresh algal biomass

Microbial fuel cells (MFCs) are energy transducers that convert organic matter directly into electricity, via the anaerobic respiration of electro-active microorganisms. An avenue of research in this field is to employ algae as the organic carbon fuel source for the MFCs. However, in all studies demonstrating the feasibility of this principle, the algal biomass has always been pre-treated prior to being fed to MFCs, e.g. centrifuged, dried, ground into powder, and/or treated by acid-thermal processes. The alternative presented here, is a flow-through system whereby the MFCs were continuously fed by fresh algal biomass. The system consisted of i) a culture of Synechococcus leopoliensis grown continuously in a photo-chemostat, ii) a pre-digester initiating the digestion of the phototrophs and producing a fuel devoid of oxygen, and iii) a cascade of 9 MFCs, hydraulically and electrically independent. This compartmental system could in theory produce 42W of electrical power per cubic metre of fresh culture (6·105cellsmL−1).

A Compartmental Lateral Inhibition System to Generate Contrasting Patterns.

We propose a lateral inhibition system and analyze contrasting patterns of gene expression. The system consists of a set of compartments interconnected by channels. Each compartment contains a colony of cells that produce diffusible molecules to be detected by the neighboring colonies. Each cell is equipped with an inhibitory circuit that reduces its production when the detected signal is sufficiently strong. We characterize the parameter range in which steady-state patterns emerge.

Adaptive Synchronization of Diffusively Coupled Systems

We present an adaptive algorithm that guarantees synchronization in diffusively coupled systems. We first consider compartmental systems of ODEs where variables in each compartment are interconnected through diffusion terms with like variables in other compartments. Each set of variables may have its own weighted undirected graph describing the topology of the interconnection between compartments. The link weights are updated adaptively according to the magnitude of the difference between neighboring agents connected by each link. We show that an incremental passivity property is fundamental in guaranteeing output synchronization. We next consider reaction-diffusion PDEs with Neumann boundary conditions and derive an analogous algorithm guaranteeing spatial homogenization of the solutions. We provide several numerical examples demonstrating the results.

Compartmented microfluidic bioreactor system using magnetic enzyme immobilisates for fast small‐scale biotransformation studies

In the last decade, microfluidic bioreactor systems became increasingly important due to their high suitability for lab‐on‐a‐chip applications and resource‐saving experiments with small sample volumes. Here, a prototype of a microfluidic device for fast small‐scale investigations of enzymatic and biochemical reactions is introduced. Single or consecutive enzyme‐catalyzed reactions can be implemented within compartmented reaction environments separated by immiscible fluidic plugs. By immobilizing one of the reactants onto magnetic microcarriers, a fast and easy separation of the reaction products is possible allowing the realization of a sequence of different reaction steps with different enzymes and varying chemical environments. Besides permanent magnetic fields for separation processes, alternating electromagnetic fields can be applied to resuspend the carriers. This leads to an intense mixing as well as even microcarrier distribution within the compartment. In a proof of concept, kinetic studies of HRP immobilized onto polyvinyl alcohol‐magnetite composite microcarriers are presented. The results showed a specific enzyme activity of approximately 89 units per gram immobilized biocatalyst under the applied reaction conditions. In addition, results of recycling experiments point out the importance of the magnetically induced resuspension. While ten times reuse with immobilisate resuspension resulted in substrate conversion yields between 95 and 65%, the same experiment without the magnetically induced resuspension showed conversion yields below 10% over all cycles.

Current Ideas about Prebiological Compartmentalization.

Contemporary biological cells are highly sophisticated dynamic compartment systems which separate an internal volume from the external medium through a boundary, which controls, in complex ways, the exchange of matter and energy between the cell’s interior and the environment. Since such compartmentalization is a fundamental principle of all forms of life, scenarios have been elaborated about the emergence of prebiological compartments on early Earth, in particular about their likely structural characteristics and dynamic features. Chemical systems that consist of potentially prebiological compartments and chemical reaction networks have been designed to model pre-cellular systems. These systems are often referred to as “protocells”. Past and current protocell model systems are presented and compared. Since the prebiotic formation of cell-like compartments is directly linked to the prebiotic availability of compartment building blocks, a few aspects on the likely chemical inventory on the early Earth are also summarized.

The number of alphaherpesvirus particles infecting axons and the axonal protein repertoire determines the outcome of neuronal infection.

ABSTRACTInfection by alphaherpesviruses invariably results in invasion of the peripheral nervous system (PNS) and establishment of either a latent or productive infection. Infection begins with long-distance retrograde transport of viral capsids and tegument proteins in axons toward the neuronal nuclei. Initial steps of axonal entry, retrograde transport, and replication in neuronal nuclei are poorly understood. To better understand how the mode of infection in the PNS is determined, we utilized a compartmented neuron culturing system where distal axons of PNS neurons are physically separated from cell bodies. We infected isolated axons with fluorescent-protein-tagged pseudorabies virus (PRV) particles and monitored viral entry and transport in axons and replication in cell bodies during low and high multiplicities of infection (MOIs of 0.01 to 100). We found a threshold for efficient retrograde transport in axons between MOIs of 1 and 10 and a threshold for productive infection in the neuronal cell bodies between MOIs of 1 and 0.1. Below an MOI of 0.1, the viral genomes that moved to neuronal nuclei were silenced. These genomes can be reactivated after superinfection by a nonreplicating virus, but not by a replicating virus. We further showed that viral particles at high-MOI infections compete for axonal proteins and that this competition determines the number of viral particles reaching the nuclei. Using mass spectrometry, we identified axonal proteins that are differentially regulated by PRV infection. Our results demonstrate the impact of the multiplicity of infection and the axonal milieu on the establishment of neuronal infection initiated from axons.

Cr Stable Isotope Fractionation in Arbuscular Mycorrhizal Dandelion and Cr Uptake by Extraradical Mycelium

As common soil fungi that form symbioses with most terrestrial plants, arbuscular mycorrhizal (AM) fungi play an important role in plant adaptation to chromium (Cr) contamination. However, little information is available on the underlying mechanisms of AM symbiosis on plant Cr resistance. In this study, dandelion (Taraxacum platypecidum Diels.) was grown with and without inoculation of the AM fungus Rhizophagus irregularis and Cr uptake by extraradical mycelium (ERM) was investigated by a compartmented cultivation system using a Cr stable isotope tracer. The results indicated that AM symbiosis increased plant dry weights and P concentrations but decreased shoot Cr concentrations. Using the Cr stable isotope tracer technology, the work provided possible evidences of Cr uptake and transport by ERM, and confirmed the enhancement of root Cr stabilization by AM symbiosis. This study also indicated an enrichment of lighter Cr isotopes in shoots during Cr translocation from roots to shoots in mycorrhizal plants.

Robust global identifiability theory using potentials—Application to compartmental models

This paper presents a global practical identifiability theory for analyzing and identifying linear and nonlinear compartmental models. The compartmental system is prolonged onto the potential jet space to formulate a set of input–output equations that are integrals in terms of the measured data, which allows for robust identification of parameters without requiring any simulation of the model differential equations. Two classes of linear and non-linear compartmental models are considered. The theory is first applied to analyze the linear nitrous oxide (N2O) uptake model. The fitting accuracy of the identified models from differential jet space and potential jet space identifiability theories is compared with a realistic noise level of 3% which is derived from sensor noise data in the literature. The potential jet space approach gave a match that was well within the coefficient of variation. The differential jet space formulation was unstable and not suitable for parameter identification. The proposed theory is then applied to a nonlinear immunological model for mastitis in cows. In addition, the model formulation is extended to include an iterative method which allows initial conditions to be accurately identified. With up to 10% noise, the potential jet space theory predicts the normalized population concentration infected with pathogens, to within 9% of the true curve.

Reversible reconfiguration of DNA origami nanochambers monitored by single-molecule FRET.

Today, DNA nanotechnology is one of the methods of choice to achieve spatiotemporal control of matter at the nanoscale. By combining the peculiar spatial addressability of DNA origami structures with the switchable mechanical movement of small DNA motifs, we constructed reconfigurable DNA nanochambers as dynamic compartmentalization systems. The reversible extension and contraction of the inner cavity of the structures was used to control the distance-dependent energy transfer between two preloaded fluorophores. Interestingly, single-molecule FRET studies revealed that the kinetics of the process are strongly affected by the choice of the switchable motifs and/or actuator sequences, thus offering a valid method for fine-tuning the dynamic properties of large DNA nanostructures. We envisage that the proposed DNA nanochambers may function as model structures for artificial biomimetic compartments and transport systems.

Global dynamics of a compartmental system modeling ectoparasite-borne diseases

Global dynamics of a compartmental system modeling ectoparasite-borne diseases

Effects of root iron plaque on selenite and selenate dynamics in rhizosphere and uptake by rice (Oryza sativa)

Iron plaque commonly forms on rice root surfaces under flooded conditions. However, little is known about the role of iron plaque in Se movement from rhizosphere to plant. A compartmented soil-quartz sand culture system was applied to investigate the effects of iron plaque on Se uptake by rice and document Se speciation dynamics in soil solution under flooded conditions. Rice seedlings were planted in a nylon bag containing sand and surrounded by soil amended with Se combined at rates of 0 or 0.5 mg of Se kg−1 of soil in the form of selenate or selenite. Plants were harvested at seedling stage and at maturity. Fe and Se concentrations in soil solution, in DCB extracts and Se concentrations in rice roots and shoots were determined. A visible reddish coating on root surfaces could be observed when sampled at the seedling stage and at maturity. Iron plaque on root surfaces greatly influenced Se uptake and had a higher affinity for selenite. The distribution of Se in different components of rice seedlings followed iron plaque > shoot > root, while it followed shoot > root > iron plaque at maturity. The addition of Se initially increased the soluble Se concentrations, and selenate was the main species in soil solution. Iron plaque greatly influenced Se uptake and might act as a pool to Se uptake during rice growth. Selenate or selenite addition to paddy soil showed the same effect in increasing Se concentrations in rice grain.

Visualizing endocytotic pathways at transmission electron microscopy via diaminobenzidine photo-oxidation by a fluorescent cell-membrane dye.

The endocytotic pathway involves a complex, dynamic and interacting system of intracellular compartments. PKH26 is a fluorescent dye specific for long-lasting cell membrane labelling which has been successfully used for investigating cell internalization processes, at either flow cytometry or fluorescence microscopy. In the present work, diaminobenzidine photo-oxidation was tested as a procedure to detect PKH26 dye at transmission electron microscopy. Our results demonstrated that DAB photo-oxidation is a suitable technique to specifically visualise this fluorescent dye at the ultrastructural level: the distribution of the granular dark reaction product perfectly matches the pattern of the fluorescence staining, and the electron density of the fine precipitates makes the signal evident and precisely detectable on the different subcellular compartments involved in the plasma membrane internalization routes.

Моделирование показателей функциональных систем организма человека на основе двухкластерной трехкомпартментной системы управления

Processes simulation is one of the main directions in science and technology. In the presence of a simple model of the process, the results of the process before it starts can be obtained. The simulation of complex processes (systems) within the standard methods of computing and simulation software runs into difficulties because of the chaotic dynamics of such systems. The number of models that allow to describe the complex biological processes of dynamic systems is extremely small, because it is impossible to repeat the same results of experiments based on deterministic or stochastic models. The authors propose a model that allows the description of the state vector of a person within tree compartmental two-cluster systems management. The model is implemented using the package of applied programs that demonstrate the performance of each cluster separately. On the model output signals are obtained, they are compared with real experiments and the resulting signals. Signals obtained at the output of the simulation model signals show different values of external control actions in which the change in the properties of the output signal. Control signal and the output signals respectively were divided into four main components that have the same name counterparts with complex biological dynamical systems.

Impact of potassium on plant uptake of non-exchangeable NH4 +-N

Release of ‘non-exchangeable’ NH4 +-N from interlayers of 2:1 clay minerals is postulated to depend not only on soil solution NH4 +-N concentration but also on the concentration of K+ and Ca2+. Concentrations of all three cations are altered in rhizosphere compared to soil solution at larger distance from the root surface. Non-exchangeable NH4 +-N pool was labelled with 15 N. Treatments including application of K+, Ca2+ and K+ + Ca2+ were established. In a compartment system approach we analysed changes in soil solution concentrations of 15NH4 +-N, 15NO3 −-N, K+ and Ca2+ in situ at different distances from the root surface over time and related them to the release of non-exchangeable 15NH4 +-N and uptake of 15 N by plants. The 15 N enrichment in plant tissue was significantly lower in treatments with K+ application compared to those without. This was in line with smaller depletion of non-exchangeable 15NH4 +-N in the rhizosphere for these treatments and also with lower 15 N abundance in soil solution NO3 −-N fraction. Hence, K+ application hampered the release of NH4 + from the interlayers. A promoting effect of increasing Ca2+ concentrations on release of non-exchangeable NH4 +-N could not be evaluated since the Ca2+ concentration in soil solution was largely controlled by small amounts of carbonate contained in the substrate and thus the addition of Ca2+ did not result in a relevant increase of soil solution Ca2+ concentration as originally intended. The use of 15 N to follow the fate of non-exchangeable NH4 +-N proved very useful as it provides a higher sensitivity for all measured fractions compared to total N. However, as soil N fractions equilibrate with each other labelling one fraction exclusively is not possible.

Performance of an Adaptive Controller for the Neuromuscular Blockade Based on Inversion of a Wiener Model

AbstractAn adaptive controller based on a minimally parameterized parsimonious Wiener model for the effect of the muscle relaxant rocuronium in the neuromuscular blockade is presented. The controller structure combines inversion of the recursively identified static nonlinearity of the Wiener model with a positive compartmental control law for the linearized system. The overall strategy exploits the fact that the model has only two parameters, which are estimated by an extended Kalman filter. Due to the fact that the positive control law for total mass conservation of compartmental systems is only proven to be convergent for time‐invariant systems, the identification of the parameter in the linear block of the minimally parameterized parsimonious Wiener model is stopped when the controller is turned on. The controller was implemented in the platform Galeno and tested in simulation and in thirteen real cases of patients under general anesthesia. The good reference tracking results and robustness to noise show the reliability of the proposed strategy.

Management of the open abdomen using vacuum-assisted wound closure and mesh-mediated fascial traction.

The open abdomen has become an accepted treatment option of critically ill patients with severe intra-abdominal conditions. Fascial closure is a particular challenge in patients with peritonitis. This study investigates whether fascial closure rates can be increased in peritonitis patients by using an algorithm that combines vacuum-assisted wound closure and mesh-mediated fascial traction. Moreover, fascial closure rates for patients with peritonitis, trauma or abdominal compartment system (ACS) are compared. Data were collected prospectively from all patients who underwent open abdomen management at our institution from 2006 to 2012. All patients were treated under a standardised algorithm that combines vacuum-assisted closure and mesh placement at the fascial level. During the study period, 53 patients (mean age 53 years) underwent open abdomen management for a mean duration of 15 days. Indications for leaving the abdomen open were peritonitis (51 %), trauma (26 %), and ACS or abdominal wall dehiscence (23 %). The fascial closure rate was 79 % in an intention-to-treat analysis and 89 % in a per-protocol analysis. Mortality was 13 %. No patient developed an enteroatmospheric fistula or abdominal wall dehiscence after closure. The mean duration of treatment was significantly longer in peritonitis patients (20 days) than in patients without peritonitis (10 days) (p = 0.03). There were no significant differences in fascial closure rates between patients with peritonitis (87 %), trauma (85 %), and ACS or abdominal wall dehiscence (100 %) (p = 0.647). Regardless of the underlying pathology, high fascial closure rates can be achieved using a combination of vacuum-assisted closure and mesh-mediated fascial traction.

Linear compartmental systems. III. Application to enzymatic reactions

In this paper we extend to enzyme systems the results previously obtained in paper I of this series for linear compartmental systems. We obtain the time course equations for both the enzyme and ligand species involved in the reaction mechanisms, which fit a general enzyme system model when the connections between the different enzyme species are of first or pseudofirst order. The kinetic equations obtained here for a given species, enzyme or ligand have the advantage over all previous equations described in the literature, in that they are in the most simplified form possible, since they only contain the kinetic parameters and initial concentrations of the enzymatic reaction which really have some influence on the time progress curves of the species under study. These kinetic equations are denominated optimized equation to distinguish them from the others, which shall call non-optimized equations. We discuss those cases when both types of equation coincide and we show how, when they do not coincide, the non-optimized equations can be simplified to the optimized ones. Therefore, we show that the optimized equations could be used in all cases to avoid the need of subsequent simplifications to eliminate the parameters that play no role in the corresponding time equations. To illustrate the use of this procedure we will apply it to two simple examples of enzymatic reactions.