Compartmental Systems Research Articles

Numerical Simulation and Optimization of a Phase-Change Energy Storage Box in a Modular Mobile Thermal Energy Supply System

Featuring phase-change energy storage, a mobile thermal energy supply system (M-TES) demonstrates remarkable waste heat transfer capabilities across various spatial scales and temporal durations, thereby effectively optimizing the localized energy distribution structure—a pivotal contribution to the attainment of objectives such as “carbon peak” and “carbon neutral”. To heighten the efficiency of energy transfer for mobile heating, this research introduces the innovative concept of modular storage and transportation. This concept is brought to life through the development of a meticulously designed modular mobile phase-change energy storage compartment system. Employing computational fluid dynamics (CFD), an in-depth exploration into the performance of the modular M-TES container and the adapted phase-change material (PCM) is conducted. By implementing fin arrangements on the inner wall of the heat storage module, a remarkable upsurge in the liquid phase-transition rate of the phase-change material is achieved in comparison to the design lacking fins—this improvement approximating around 30%. However, it is essential to acknowledge that the augmentation in heat transfer gradually recedes with the proliferation of fins or an escalation in their height. Moreover, the integration of expanded graphite into erythritol emerges as profoundly effective in amplifying the thermal conductivity of the PCM. Notably, with the addition of a 15.2% volume fraction of expanded graphite to erythritol, the duration of heat storage experiences a drastic reduction to nearly 10% of its original duration, thereby signifying a momentous advancement in thermal performance.

The impact of Lévy noise on the threshold dynamics of a stochastic susceptible‐vaccinated‐infected‐recovered epidemic model with general incidence functions

Compartmental systems like the well‐famed SIR, SEIR, SQIR, SVIR, and their variants are efficient tools for the mathematical modeling of infectious illnesses, and they permit us to get a clear picture of how they proliferate. In actuality, the aleatory fluctuations factors present in the natural environment like storm surges, weather changes, and seismic tremors make the dissemination of epidemics susceptible to some randomness. This calls for a stronger mathematical formulation that takes into consideration this stochasticity effect. From this perspective, and in order to highlight in the same time the effect of the vaccination strategy, we survey in this paper an SVIR model with general incidence rates that is disturbed by both Brownian motions and Lévy jumps. Initially, we establish its well‐posedness in the sense that it has a unique positive and global‐in‐time solution. Then, we rely on some assumptions and nonstandard analytic techniques, to derive sufficient and almost necessary conditions for extinction, persistence in the mean, and also weak persistence. More explicitly, we identify firstly under some hypotheses a threshold between extinction and persistence in the mean. In other phrases, if , the infected population dies out while it persists in the mean when . Then, and by modifying the hypothetical framework in order to cover more incidence rates, we prove that can act also as a threshold between extinction and weak persistence. At last, we provide some numerical simulations to corroborate our findings and cover some particular cases of response functions.

Primitive membraneless compartments as a window into the earliest cells.

What did the first cells on Earth look like? This is an unanswered mystery investigated by researchers in the origins of life field. While at some point cells must have developed membranes, genetic components, and catalytic cycles and catalysts, when the earliest cells developed these is not clear. One system which could shed light into the structure and function of the first cells on Earth is membraneless compartments generated from phase separation, perhaps before or as a precursor to the advent of membrane-bound compartmentalization. Here, we briefly comment on two prebiotically relevant membraneless compartment systems: coacervates and polyester microdroplets. This discussion seeks to highlight the current understanding of these systems and to pose unanswered questions as a challenge to the field at large.

Changes in overall and inter-variability of runoff and soil loss for a loess soil resulted from a freezing-thawing cycle.

The soil freeze-thaw process is a transition phase of soil water in cold areas that influences the soil's hydrological behavior. However, dynamic phenomena and corresponding consequences have yet to be studied adequately. Therefore, the present study was planned to comparatively analyze the effects of a freezing-thawing cycle on the hydrologic behaviors of loess soil from northeast Iran. Small-size (0.5 × 0.50m) erosion plots were subjected to a freezing-thawing cycle under governing conditions of the region of the origin soil. The plots were subjected to a freezing-thawing treatment by inducing cold air until the temperature declined to below - 20°C and lasted for 3days using a cooling compartment system and then were kept in the laboratory with an ambient temperature of above 10°C for 2days. The treated plots and untreated plots were then exposed to a simulated rainfall with an intensity of 72mmh-1 and 0.5h duration while they were placed on a slope of 20%. The results indicated that the hybrid processes of freezing-thawing and splash and inter-rill erosions significantly increased runoff generation and soil loss. The time to runoff, runoff volume, and soil loss were 1.65 times less and 1.38 and 2.90 times more, respectively, compared to those reported for the control treatment with significant differences (p < 0.006). The performance of ice lenses, freezing fronts, and the creation of near-saturation moisture after completing the cycle were identified as the most critical factors affecting the different soil behaviors under the frozen-thawed cycle.

Preparation and Catalytic Properties of Carbonic Anhydrase Conjugated to Liposomes through a Bis-Aryl Hydrazone Bond.

Liposomes (lipid vesicles) with sizes of about 100-200 nm carrying surface-bound (immobilized) water-soluble enzymes are functionalized molecular compartment systems for possible applications, for example, as therapeutic materials or as catalytic reaction units for running reactions in aqueous media in vitro. One way of covalently attaching enzyme molecules under mild conditions in a controlled way to the surface of preformed liposomes is to apply the spectrophotometrically traceable bis-aryl hydrazone (BAH) bond between the liposome and the enzyme molecules of interest. Using bovine carbonic anhydrase (BCA), an aqueous dispersion of liposome-BAH-BCA - conjugates of defined composition was prepared. The liposomes used consisted of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), N-(methylpolyoxyethylene oxycarbonyl)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE-PEG), and N-(aminopropylpolyoxyethylene oxycarbonyl)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE-PEG-NH2). The amino group of some of the DSPE-PEG-NH2 molecules present in the liposomes were converted into an aromatic aldehyde, which (after purification) reacted with (purified) BCA molecules that had on their surface on average one acetone protected aromatic hydrazine. After purification of the liposome-BAH-BCA conjugate dispersion obtained, it was characterized in terms of (i) BCA activity, (ii) overall BCA structure, and (iii) storage stability. For an average liposome of 138 nm diameter, about 1200 BCA molecules were attached to the outer liposome surface. Liposomally bound BCA was found to exhibit (i) similar catalytic activity at 25 °C and (ii) similar storage stability when stored in a dispersed state in aqueous solution at 4 °C as free BCA. Measurements at 5 °C clearly showed that liposome-BAH-BCA is able to catalyze the hydration of carbon dioxide to hydrogen carbonate.

Titanium dioxide effect on the decolourisation of organic dyes Remazol Black B using electrocoagulation in situ-Fe2O3

ABSTRACT In this research, combination of TiO2 pillared clay with electrocoagulation in situ-Fe2O3 provides excellent performance to remove dyes water waste Remazol Black B(RBB). The best TiO2:clay ratio is 1:6, with highest degradation performance 89.8% in 30 minutes photodegradation process under UV light 254 nm. The excellent performance of pillared clay causes mesoporous pore that can be achieved by pillarisation of the clay layer using titanium dioxide sol which was made by diluting TiCl4 in ethanol solution. Besides, the excellent electrocoagulation performance was conducted by dual compartment system using 10ppm of RBB in the alkaline system containing 1 g NaCl as an electrolyte at potential apply+6 V with 98% degradation efficiency in 3 hours running compared to the 78% in single compartment system towards the formation of in situ-Fe2O3 that is directly driven by formation of intermediate species Fe(OH)3. This optimum decolourisation efficiency was gained at 0.1 A, pH 7.2 and 2 cm of inter-electrode distance. The power consumption was very low with the excellent and fast degradation performance towards organic dyes Remazol Black B, where this tandem cell can produce 100 mL clean water using 0.0052 kWh energy with cheaper cost operation.

The effect of pests and pathogens on forest harvesting regimes: A bioeconomic model

Pests and diseases are an existential threat to trees in forests and woodlands. There is, therefore, a pressing need to use ecological and bioeconomic models to inform forest managers on control and mitigation strategies. For example, the incidence of Dothistroma needle blight in the UK has increased rapidly since the 1990s, and it is a significant threat to the productivity of commercial forestry. Climatic changes are expected to exacerbate this problem further. Control of the disease in the UK primarily focuses on good stand management through pre-commercial thinning; similar practices are widely used in commercial forests worldwide. Forest managers would benefit from evidence on the effectiveness of this precautionary strategy (in comparison to its alternatives) to reduce disease impacts and increase the value extracted from timber. In this paper, we develop a bioeconomic model to determine the economically optimal harvesting regime – in terms of thinning and rotation – of an even-aged plantation under the risk of an invading pest. We extend a Schaefer–Faustmann model to include a compartmental epidemiological system that governs timber growth and disease spread. We analyse a set of management regimes, including the timing of the final clear-felling of the forest and the timing and level of earlier thinning. Thus, in our approach, forest managers decide whether and when to thin and must balance (i) harvesting before infection destroys the timber’s value and (ii) exploiting the forest’s density-dependent growth. We use a sensitivity analysis with respect to the disease spread and impact on the tree dynamics to demonstrate that, in the presence of disease, thinning can significantly improve the net present value of the plantation if applied correctly. Furthermore, if thinning reduces the transmission rate significantly, the priority is to protect the final harvest, and rotations extend while the thinning time shortens. Our study provides a framework to help design appropriate forest management strategies in the presence of disease.

English

Development of the livestock sector in South Africa has the potential to contribute significantly to national development. The aim of this study was to explore challenges and propose recommendations to support livestock sector development in South Africa using a stakeholder-driven approach. Interviews with high-level stakeholders across major livestock industries were conducted to gather insights. Responses were verified by a literature review and supplemented with an event study analysis on parameters for livestock production and exports. Interview respondents revealed livestock disease management in the face of increasing disease burden, high input costs, and limited government resources as a major challenge to national livestock-sector development. Implementation of national and international regulations on controlled diseases severely limits profitability. Emerging farmers are discouraged from investing in livestock disease management and are thus excluded from entering and remaining in the commercial value chains. Inclusive growth of the sector can be achieved through strengthening public-private partnerships through joint mentorship, training, and awareness-raising programmes. Evidence- and risk-based approaches to the national and international regulations and official guidance on outbreak management are needed. National animal identification and traceability systems and wider adoption of compartment systems for biosecurity, growth stimulants and poultry cages can enhance disease management and exports. Key words: African swine fever, event study analysis, foot-and-mouth disease, highly pathogenic avian influenza, livestock disease, livestock sector development, South Africa, stakeholder-driven approach.

A pipeline for testing drug mechanism of action and combination therapies: From microarray data to simulations via Linear-In-Flux-Expressions: Testing four-drug combinations for tuberculosis treatment

Computational methods are becoming commonly used in many areas of medical research. Recently, the modeling of biological mechanisms associated with disease pathophysiology have benefited from approaches such as Quantitative Systems Pharmacology (briefly QSP) and Physiologically Based Pharmacokinetics (briefly PBPK). These methodologies show the potential to enhance, if not substitute animal models. The main reasons for this success are the high accuracy and low cost.Solid mathematical foundations of such methods, such as compartmental systems and flux balance analysis, provide a good base on which to build computational tools. However, there are many choices to be made in model design, that will have a large impact on how these methods perform as we scale up the network or perturb the system to uncover the mechanisms of action of new compounds or therapy combinations.A computational pipeline is presented here that starts with available-omic data and utilizes advanced mathematical simulations to inform the modeling of a biochemical system. Specific attention is devoted to creating a modular workflow, including the mathematical rigorous tools to represent complex chemical reactions, and modeling drug action in terms of its impact on multiple pathways. An application to optimizing combination therapy for tuberculosis shows the potential of the approach.

Pool dynamics of time-dependent compartmental systems with application to the terrestrial carbon cycle.

Compartmental models play an important role to describe the dynamics of systems that involve mass movements between different types of pools. We develop a theory to analyse the average ages of mass in different pools in a linear compartmental system with time-dependent (i.e. non-autonomous) transfer rates, which involves transit times that characterize the average time a particle has spent in a particular pool. We apply our theoretical results to investigate a nine-dimensional compartmental system with time-dependent fluxes between pools modelling the carbon cycle which is a modification of the Carnegie-Ames-Stanford approach model. Knowledge of transit time and mean age allows calculation of carbon storage in a pool as a function of time. The general result that has important implications for understanding and managing carbon storage is that the change in storage in different pools does not change monotonically through time: as rates change monotonically a pool which initially shows a decrease may then show an increase in storage or vice versa. Thus caution is needed in extrapolating even the direction of future changes in storage in carbon storage in different pools with global change.

Designed Synthesis of Compartmented Bienzyme Biocatalysts Based on Core–Shell Zeolitic Imidazole Framework Nanostructures (Small 7/2023)

Compartmented Bienzyme Biocatalysts Biomimetic mineralization and slow seed-induced nucleation strategy enables the synthesis of compartmented bienzyme system based on core-shell [email protected] in aqueous solution. Bienzyme can be accurately localized into the shell and core with uniform distribution. The optimization of pore structure and bienzyme positional assembly provides a guidance for preparing efficient multi-enzyme biocatalysts. More details can be found in article number 2206606 by Liang Qi, Hongsheng Liu, and co-workers.

Spatial modeling of crime dynamics: Patch and reaction–diffusion compartmental systems

We study the dynamics of abstract models for crime evolution. The population is divided into three compartments, taking into account the participation in crime and incarceration. Individuals transit between the three segments, assuming that having more contact with criminally active people increases one's risk of learning and acquiring the same traits; essentially, crime is regarded as a social epidemic. In the literature, there are several models of this type, based on spatial homogeneity and ordinary differential equations. However, these ideas have not been extended to account for spatial variability. Here, we achieve this target with discrete and continuous forms of space: patch and reaction–diffusion compartmental systems, respectively. We build the models and focus on the effect of the basic reproduction number on the long‐term dynamics of crime (persistence or disappearance). Several theoretical results are presented, which are supported by numerical simulations.

Field Measurement of Air Velocity and Temperature Factors that Influence the Thermal Comfort in Shuttle Bus

Good public transportation that can offer a pleasant peaceful and relaxing environment is necessary for improving people's interest in using it. Thermal comfort is determined in this study by measuring the air velocity and temperature of the air-conditioning from the outlet. Both data are taken using a digital anemometer and thermocouple with three replications for reproducibility. For data collection, a 10-row shuttle bus was held immobile for 30 minutes. According to the data, outlet 5 received the highest air velocity and the lowest temperature, at 9.12 ms-1 and 13.6 °C, respectively. It was also discovered that the design of the air-conditioning ducting impacts the reachability of cooled air to the farthest outlets, adversely affecting the target cool temperature and passenger comfortability. It is suggested that in order to promote the attractiveness of public transportation, the inner bus compartment and air-conditioning system in hot countries should prioritise thermal comfort.

Electrochemical Performance of Galvanic Cell with Silver Coated Cathode in One Compartment System Using Seawater as Electrolyte

This research was carried out to evaluate the electrochemical performance of a galvanic cell using seawater as an electrolyte. The cell was designed to have a volume of 200 mL and equipped with Zn as an anode and Ag-coated Cu as a cathode (Cu(Ag)-Zn system) in order to suppress the corrosion of Cu. As a comparison, the same experiment with the use of uncoated Cu as a cathode (Cu-Zn system) was also conducted. To conduct the experiment, a system was assembled by connecting 20 cells in series and placed in a closed container filled with seawater. The experiment was run for 72 hours, divided into three 24-hour cycles, by replacing the seawater every 24 hours. The performance of the system was evaluated in terms of open circuit voltage, close circuit voltage, current, light intensity, internal resistance, and power. The experimental results show that the corrosion rate of Cu coated with silver was smaller than that of uncoated Cu. Compared to the performance of the Cu-Zn system, it was also found that the Cu(Ag)-Zn system produced higher power and light intensity, which is in accordance with its smaller internal resistance. The overall experimental results indicate better performance of Cu(Ag)-Zn system and this better performance is attributed to the significantly lower corrosion rate of Cu(Ag) cathode which signifies the role of Ag layer to protect the Cu from attack by seawater. As a result, the Cu(Ag)-Zn system maintained the cathode corrosion rate with a ratio of 0.19. The percentage decrease of the OCV of the Cu(Ag)-Zn system was 6.14%, the CCV on the third day was 0.99%, the current was 36.68%, and the power was 37.83%.

Process and System Clearances in Pharmacokinetic Models: Our Basic Clearance Concepts Are Correct.

Clearances are important parameters in pharmacokinetic (PK) models. All clearances in PK models are either process clearances that include diffusion, transport, and metabolism clearances or system clearances that include organ and systemic clearance. Clearance and volume of distribution are two independent parameters that characterize drug disposition in both individual compartments and systems of compartments. In this minireview, we show that systemic and organ clearances are net clearances that can be easily derived by partition analysis. When drugs are eliminated from the central compartment by first-order processes, systemic clearance is constant. When drugs are eliminated from a peripheral compartment, instantaneous systemic clearance will vary with time. However, average clearance and clearance at steady state will be constant and will equal dose divided by area under the curve. We show that peripheral elimination will not have a large impact on most pharmacokinetic analyses and that standard models of organ and systemic clearance are useful and appropriate. SIGNIFICANCE STATEMENT: There are two basic kinds of clearances used in pharmacokinetic models, process and system clearances. We show that organ and systemic clearances are net clearances with blood or plasma as the driving concentration. For linear pharmacokinetics, clearance is constant for elimination from the central compartment but varies with time for peripheral elimination. Despite the different kinds of clearance parameters and models, standard clearance models and concepts remain valid.

3D printing of LEGO® like designs with tailored release profiles for treatment of sleep disorder

3D printed LEGO®-like designs are an attractive approach for the development of compartmental delivery systems due to their potential for dose personalisation through the customisation of drug release profiles. Additive manufacturing technologies such as Fused Deposition Modelling (FDM) are ideal for the printing of structures with complex geometries and various sizes. This study is a paradigm for the fabrication of 3D printed LEGO® -like tablets by altering the design of the modular units and the filament composition for the delivery of different drug substances. By using a combination of placebo and drug loaded compartments comprising of immediate release (hydroxypropyl cellulose) and pH dependant polymers (hypromellose acetate succinate) we were able to customise the release kinetics of melatonin and caffeine that can potentially be used for the treatment of sleep disorders. The LEGO® -like compartments were designed to achieve immediate release of melatonin followed by variable lag times and controlled release of caffeine.

Palmitoylation and PDE6δ regulate membrane-compartment-specific substrate ubiquitylation and degradation

Substrate degradation by the ubiquitin proteasome system (UPS) in specific membrane compartments remains elusive. Here, we show that the interplay of two lipid modifications and PDE6δ regulates compartmental substrate targeting via the SCFFBXL2. FBXL2 is palmitoylated in a prenylation-dependent manner on cysteines 417 and 419 juxtaposed to the CaaX motif. Palmitoylation/depalmitoylation regulates its subcellular trafficking for substrate engagement and degradation. To control its subcellular distribution, lipid-modified FBXL2 interacts with PDE6δ. Perturbing the equilibrium between FBXL2 and PDE6δ disrupts the delivery of FBXL2 to all membrane compartments, whereas depalmitoylated FBXL2 is enriched on the endoplasmic reticulum (ER). Depalmitoylated FBXL2(C417S/C419S) promotes the degradation of IP3R3 at the ER, inhibits IP3R3-dependent mitochondrial calcium overload, and counteracts calcium-dependent cell death upon oxidative stress. In contrast, disrupting the PDE6δ-FBXL2 equilibrium has the opposite effect. These findings describe a mechanism underlying spatially-restricted substrate degradation and suggest that inhibition of FBXL2 palmitoylation and/or binding to PDE6δ may offer therapeutic benefits.

Fractional time-invariant compartmental linear systems

Fractional time-invariant compartmental linear systems

Fast simulation of pharmacokinetics

Fast simulation of linear time-invariant (LTI) pharmacokinetic (PK) models is crucial to mixed-effect modeling techniques, used extensively in pharmacological research and development. The by far most common LTI PK models are particularly structured compartmental systems with one, two or three compartments. Here we develop and demonstrate very efficient, and down to machine precision exact, simulators for those structures. Our proposed method is benchmarked against state-of-the art software for simulation of linear systems, using a clinically relevant data set.

On Decentralized H-Infinity Optimal Positive Systems

This letter gives a closed-form expression for an H-infinity optimal controller with diagonal gain matrix. This phenomenon occurs for certain network systems with acyclic graphs, and potential applications include irrigation networks. Moreover, the above is identified as a special case of a particular controller structure which is shown to be H-infinity optimal if the controller and the resulting closed-loop system are positive. A subsequent result then establishes a connection with open-loop positive systems, and its usefulness in applications is demonstrated on a large set of compartmental systems.