Closed System Approach Research Articles

Innovative Ex-Situ catalyst bed integration for LDPE plastic Pyrolysis: A thermodynamically closed system approach

The recycling of Low-Density Polyethylene (LDPE) poses a significant challenge due to its resistance to degradation and presence of impurities among the waste LDPE. This study introduces an innovative method for LDPE pyrolysis, aiming to enhance the efficiency of LDPE recycling and contribute to the circular economy of plastics. We utilized an HZSM-5 catalyst within a unique setup that incorporates a catalyst bed constructed from a quartz fibre membrane filter. This innovative hybrid method, a combination of in-situ and ex-situ modes, was designed to shield the catalyst from direct contact with undesired materials, thereby facilitating easy catalyst separation at the end of the process. Experiments were conducted in a high-pressure batch reactor, heated to 400 °C within a closed thermodynamic system. Parallel runs were performed for both pure and waste LDPE, with and without the catalyst. The catalytic pyrolysis resulted in an oil output of 40.3 % for waste LDPE and 43.5 % for pure LDPE, with a significant increase in aromatics when comparing thermal to catalytic pyrolysis. The calorific values of the pyrolysis liquids were found to be 46.2 for pure LDPE and 46.1 for waste LDPE, indicating their potential for sustainable hydrocarbon fuel synthesis. Following the catalytic pyrolysis, the spent catalyst underwent stepwise oxidation as a regeneration method, indicating a partial loss of activity but a similar influence on the degradation temperature as the fresh catalyst. This study not only presents a promising approach to LDPE recycling but also offers a comprehensive analysis of both the pyrolysis outputs and the spent catalyst. Such detailed analysis is crucial for refining the LDPE pyrolysis process and facilitating its scale-up for industrial applications.

Kelps on demand: Closed-system protocols for culturing large bull kelp sporophytes for research and restoration.

Culturing kelps for commercial, conservation, and scientific purposes is becoming increasingly widespread. However, kelp aquaculture methods are typically designed for ocean-based farms, and these methods may not be applicable for smaller scale cultivation efforts common in research and restoration. Growing kelps in closed, recirculating culture systems may address many of these constraints, yet closed system approaches have remained largely undescribed. Extensive declines of the bull kelp(Nereocystis luetkeana), an ecologically important canopy species in the Northeast Pacific, have received widespread attention and prompted numerous research and conservation initiatives. Here, we detail two approaches for cultivating N. luetkeana sporophytes in closed recirculating systems. Nereocystis luetkeana were reared as attached thalli in custom seaweed growth flumes and also free-floating in tumble culture tanks. Careful control of stocking density, water motion, aeration, and nutrient levels allowed for rapid growth and normal morphogenesis of laboratory-grown kelp. Culture systems reached up to 3 kg · m-3 , and individual thalli attained lengths of up to 6 m before the trials were terminated. Our results demonstrate the potential of recirculating, closed culture systems to overcome limitations associated with traditional culture methods. Recirculating systems enable the precise control of culture conditions, improving biosecurity and facilitating cultivar development and other research. Kelps can be grown away from the ocean or outside their native ranges, and seasonal or annual species can be produced year-round without seasonal constraints.

David Hume on history, development and happiness: interconnections

The purpose of this paper is to explore the interconnections between Hume’s thought as a philosopher, a historian and an economist, illustrated with respect to his thought on history, development and happiness. It is argued that differences in the interpretation of Hume have an epistemological origin, reflecting either a closed-system approach or some kind of open-system approach. These differences are explored in relation to Hume’s own epistemology, historiography, theory of economic development and theory of happiness. Patterns are identified in Hume’s thought which support a particular, open-system, interpretation of his contributions in each area in terms of interdependent processes.

High efficiency closed-system gene transfer using automated spinoculation

BackgroundGene transfer is an important tool for cellular therapies. Lentiviral vectors are most effectively transferred into lymphocytes or hematopoietic progenitor cells using spinoculation. To enable cGMP (current Good Manufacturing Practice)-compliant cell therapy production, we developed and compared a closed-system spinoculation method that uses cell culture bags, and an automated closed system spinoculation method to decrease technician hands on time and reduce the likelihood for microbial contamination.MethodsSepax spinoculation, bag spinoculation, and static bag transduction without spinoculation were compared for lentiviral gene transfer in lymphocytes collected by apheresis. The lymphocytes were transduced once and cultured for 9 days. The lentiviral vectors tested encoded a CD19/CD22 Bispecific Chimeric Antigen Receptor (CAR), a FGFR4-CAR, or a CD22-CAR. Sepax spinoculation times were evaluated by testing against bag spinoculation and static transduction to optimize the Sepax spin time. The Sepax spinoculation was then used to test the transduction of different CAR vectors. The performance of the process using healthy donor and a patient sample was evaluated. Functional assessment was performed of the CD19/22 and CD22 CAR T-cells using killing assays against the NALM6 tumor cell line and cytokine secretion analysis. Finally, gene expression of the transduced T-cells was examined to determine if there were any major changes that may have occurred as a result of the spinoculation process.ResultsThe process of spinoculation lead to significant enhancement in gene transfer. Sepax spinoculation using a 1-h spin time showed comparable transduction efficiency to the bag spinoculation, and much greater than the static bag transduction method (83.4%, 72.8%, 35.7% n = 3). The performance of three different methods were consistent for all lentiviral vectors tested and no significant difference was observed when using starting cells from healthy donor versus a patient sample. Sepax spinoculation does not affect the function of the CAR T-cells against tumor cells, as these cells appeared to kill target cells equally well. Spinoculation also does not appear to affect gene expression patterns that are necessary for imparting function on the cell.ConclusionsClosed system-bag spinoculation resulted in more efficient lymphocyte gene transfer than standard bag transductions without spinoculation. This method is effective for both retroviral and lentiviral vector gene transfer in lymphocytes and may be a feasible approach for gene transfer into other cell types including hematopoietic and myeloid progenitors. Sepax spinoculation further improved upon the process by offering an automated, closed system approach that significantly decreased hands-on time while also decreasing the risk of culture bag tears and microbial contamination.

Analysis: Overcoming Human Factors Challenges of Endoscope Culturing with Turbulent Fluid Flow.

Analysis: Overcoming Human Factors Challenges of Endoscope Culturing with Turbulent Fluid Flow.

Some remarks to the derivation of the \u201cgeneralized Lippmann equation\u201d

In the present communication, an attempt is made to demonstrate (once again) some of the problems with the derivation of the “generalized Lippmann equation” considered to be valid by many researchers for solid electrodes and to address the problems in the framework of the Gibbs model of the interface by using only the basic principles of thermodynamics. By surveying the relevant literature, it has been shown that during the derivation of the equation, it was completely ignored that the Gibbs-Duhem equation (i.e., the electrocapillary equation) is a mathematical consequence which follows directly from the homogeneous degree one property of the corresponding thermodynamic potential function; consequently, the resulting expression cannot be correct. Some alternative approaches have also been considered. The adequacy of the open system and the partly closed system approach has been critically discussed, together with the possibility of introducing new thermodynamic potential functions.

A new method for enamel amino acid racemization dating: A closed system approach

Abstract Analysis of the predictable breakdown of proteins and amino acids in ancient biominerals enables age estimation over the Quaternary. We postulate that enamel is a suitable biomineral for the long-term survival of endogenous amino acids. Analysis of multiple amino acids for geochronological studies is typically achieved using a RP-HPLC method. However, the low concentrations of amino acids coupled with high concentrations of inorganic species make accurate determination of amino concentrations challenging. We have developed a method for the routine preparation of multiple enamel samples using biphasic separation. Furthermore, we have shown that amino acids that exhibit effectively closed system behaviour can be isolated from enamel through an exposure time of 72 h to bleach. Elevated temperature experiments investigating the processes of intra-crystalline protein degradation (IcPD) do not appear to match the patterns from fossil samples, reinforcing the need for a comprehensive understanding of the underlying mechanisms of protein degradation. This novel preparative method isolates intra-crystalline amino acids suitable for the development of mammalian geochronologies based on enamel protein degradation. The lower rates of racemization in enamel (cf. Bithynia opercula) suggest that the enamel AAR may be able to be used as a relative dating technique over time scales >2.8 Ma. Enamel AAR has the potential to directly date mammalian remains past the limit of all other current direct dating methods, providing an invaluable tool for geochronological studies.

Energetic Effects of a Closed System Approach Including Explicit Proton and Electron Acceptors as Demonstrated by a Mononuclear Ruthenium Water Oxidation Catalyst.

When considering water oxidation catalysis theoretically, accounting for the transfer of protons and electrons from one catalytic intermediate to the next remains challenging: correction factors are usually employed to approximate the energetics of electron and proton transfer. Here these energetics were investigated using a closed system approach, which places the catalytic intermediate in a simulation box including proton and electron acceptors, as well as explicit solvent. As a proof of principle, the first two catalytic steps of the mononuclear ruthenium‐based water oxidation catalyst [Ru(cy)(bpy)(H2O)]2+ were examined using Car‐Parrinello Molecular Dynamics. This investigation shows that this approach offers added insight, not only into the free energy profile between two stable intermediates, but also into how the solvent environment impacts this dynamic evolution.

Phase Equilibria in the ZnO-“FeO”-SiO2 System in Reducing Atmosphere and in the ZnO-“FeO”-SiO2-“Cu2O” System in Equilibrium with Liquid Copper Metal at 1250 °C (1523 K)

Recent experimental studies in the ZnO-"FeO"-SiO2 system in reducing atmosphere demonstrated significant discrepancies with the current FactSage thermodynamic model developed using previous experimental data in this system in equilibrium with metallic iron and air. The present experimental study on phase equilibria in the ZnO-"FeO"-SiO2-"Cu2O" system in equilibrium with liquid copper at 1250 A degrees C (1523 K) at low copper oxide concentrations in slag was initiated and undertaken to resolve these discrepancies. A high-temperature equilibration-rapid quenching-electron-probe X-ray microanalysis (EPMA) technique using a primary phase substrate support and closed system approach with Cu metal introduced to determine effective equilibrium oxygen partial pressure from the Cu-metal/Cu2Oslag equilibria was applied to provide accurate information on the liquidus and corresponding solid compositions in the spinel, willemite, and tridymite primary phase fields. The present results confirmed the accuracy of the FactSage model, resolved discrepancies, and demonstrated significant uncertainties in the recent studies by other authors on the system in the open reducing atmosphere. The present study shows how this closed system approach can be used to obtain key thermodynamic data on phase equilibria in systems containing volatile metal species, overcoming the limitations and uncertainties encountered in conventional open gas/condensed phase equilibration with these systems. The study highlights the importance of the focus on obtaining accurate experimental data and the risks of misleading information from inadequate experimental control and analysis. The study also demonstrates that continuing in-depth critical review and analysis of the elemental reactions taking place in complex systems is an essential step in phase equilibrium research.

New Equilibrium Models of Drug-Receptor Interactions Derived from Target-Mediated Drug Disposition

In vivo analyses of pharmacological data are traditionally based on a closed system approach not incorporating turnover of target and ligand-target kinetics, but mainly focussing on ligand-target binding properties. This study incorporates information about target and ligand-target kinetics parallel to binding. In a previous paper, steady-state relationships between target- and ligand-target complex versus ligand exposure were derived and a new expression of in vivo potency was derived for a circulating target. This communication is extending the equilibrium relationships and in vivo potency expression for (i) two separate targets competing for one ligand, (ii) two different ligands competing for a single target and (iii) a single ligand-target interaction located in tissue. The derived expressions of the in vivo potencies will be useful both in drug-related discovery projects and mechanistic studies. The equilibrium states of two targets and one ligand may have implications in safety assessment, whilst the equilibrium states of two competing ligands for one target may cast light on when pharmacodynamic drug-drug interactions are important. The proposed equilibrium expressions for a peripherally located target may also be useful for small molecule interactions with extravascularly located targets. Including target turnover, ligand-target complex kinetics and binding properties in expressions of potency and efficacy will improve our understanding of within and between-individual (and across species) variability. The new expressions of potencies highlight the fact that the level of drug-induced target suppression is very much governed by target turnover properties rather than by the target expression level as such.

The Ubiquitous-Eco-City of Songdo: An Urban Systems Perspective on South Korea's Green City Approach

Since the 1980s, within the broader context of studies on smart cities, there has been a growing body of academic research on networked cities and “computable cities” by authors including Manuel Castells (Castells, 1989; Castells & Cardoso, 2005), William Mitchell (1995), Michael Batty (2005, 2013), and Rob Kitchin (2011). Over the last decade, governments in Asia have displayed an appetite and commitment to construct large scale city developments from scratch—one of the most infamous being the smart entrepreneurial city of Songdo, South Korea. Using Songdo as a case study, this paper will examine, from an urban systems perspective, some of the challenges of using a green-city model led by networked technology. More specifically, this study intends to add to the growing body of smart city literature by using an external global event—the global financial crisis in 2008—to reveal what is missing from the smart city narrative in Songdo. The paper will use the definition of an urban system and internal subsystems by Bertuglia et al. (1987) and Bertuglia, Clarke and Wilson (1994) to reveal the sensitivity and resilience of a predetermined smart city narrative. For instance, what happens if the vision moves from the originally intended international-orientated population towards remarketing the city to attract a domestic middle-class population. The lens of the financial crisis in 2008 revealed that the inherent inflexibility of a closed-system approach in Songdo was not sufficiently resilient to external shocks. The shift towards a domestic middle-class population revealed the inequality in accessing the city services in a system designed with formalized and rigid inputs and outputs. By focusing predominantly on technology, the social dimensions of the city were not part of Songdo’s smart city vocabulary. Therefore, in adopting a technologically deterministic approach (Mullins & Shwayri, 2016) to achieving efficiency and combating environmental issues, Songdo’s green city model was found insufficient in its ability to cope with the complexity and dissonance that occurs in relation to “glocal” challenges facing cities today.

Introducing a closed system approach for the investigation of chemical steps involving proton and electron transfer; as illustrated by a copper-based water oxidation catalyst.

The investigation of the catalytic mechanism of homogeneous water oxidation catalysts remains an active field of research. When examining catalytic steps theoretically, it is often difficult to account for the transfer of protons and electrons from step to step. To this end, a closed system approach is proposed which includes both proton and electron acceptors in the simulation box to allow for the description of proton-coupled electron transfer processes. Using Car-Parrinello Molecular Dynamics, a mononuclear copper water oxidation catalyst Cu(bpy)(OH)2 was used as a model system to explore this closed system approach. The exploration of this model system shows that, compared to traditional methods, this approach offers extra insight into proposed catalytic steps and allows for the clear identification of preferred reaction paths.

Alternate green approach of spent media utilization for hydrogen and for lipid production

In a view to uplift the biodiesel industry as a major energy carrier, new approach of minimizing the waste and utilizing generated waste needs to be explored. The spent media generated from the co-culture system is cost effective and can serve as renewable supplement for mixed-culture based hydrogen (H2) production and lipid production. Direct conversion of spent media along with crude glycerol (CG) at 20 g/L using heat-shock pretreated wastewater sludge resulted in 38.12 ± 0.84 mmol/L of H2. In another approach, the spent media was used as co-supplement along with fresh media at 3:2 for algal growth, resulting in 0.098 ± 0.007 g/L of lipid. The spent media contained dead biomass, residual media nutrients, biomolecules and unutilized glycerol together acting as supplementary source during H2 and lipid production. According to the closed system results, the H2 produced (1.47 × 109 L of H2) can be converted into energy (1.87 × 104 GJ) for electricity (1.77 × 104 GJ) and heat (4.32 × 103 GJ). The produced H2 can be used as in-house energy source and the lipids can be used as third generation feedstock. The study explores the utilization of CG and spent media valorization towards an efficient closed system approach for a competitive biodiesel industry.

Recent progress and trends in predictive visual analytics

A wide variety of predictive analytics techniques have been developed in statistics, machine learning and data mining; however, many of these algorithms take a black-box approach in which data is input and future predictions are output with no insight into what goes on during the process. Unfortunately, such a closed system approach often leaves little room for injecting domain expertise and can result in frustration from analysts when results seem spurious or confusing. In order to allow for more human-centric approaches, the visualization community has begun developing methods to enable users to incorporate expert knowledge into the prediction process at all stages, including data cleaning, feature selection, model building and model validation. This paper surveys current progress and trends in predictive visual analytics, identifies the common framework in which predictive visual analytics systems operate, and develops a summarization of the predictive analytics workflow.

Optimizing laboratory-based radon flux measurements for sediments

Radon flux via diffusion from sediments and other materials may be determined in the laboratory by circulating air through the sample and a radon detector in a closed loop. However, this approach is complicated by the necessity of having to determine the total air volume in the system and accounting for any small air leaks that can arise if using extended measurement periods. We designed a simple open-loop configuration that includes a measured mass of wet sediment and water inside a gas-tight reaction flask connected to a drying system and a radon-in-air analyzer. Ambient air flows through two charcoal columns before entering the reaction vessel to eliminate incoming radon. After traveling through the reaction flask, the air passes the drier and the radon analyzer and is then vented. After some time, the radon activity will reach a steady state depending upon the airflow rate. With this approach, the radon flux via diffusion is simply the product of the steady-state radon activity (Bq/m3) multiplied by the airflow rate (mL/min). We demonstrated that this setup could produce good results for materials that produce relatively high radon fluxes. We also show that a modified closed system approach, including radon removal of the incoming air by charcoal filtration in a bypass, can produce very good results including samples with very low emission rates.

Educating Amid Uncertainty

Purpose: We examine how uncertainty, both about students and the context in which they are taught, remains a persistent condition of teachers’ work in high-poverty, urban schools. We describe six schools’ organizational responses to these uncertainties, analyze how these responses reflect open- versus closed-system approaches, and examine how this orientation affects teachers’ work. Research Methods: We draw on interviews with a diverse set of 95 teachers and administrators across a purposive sample of six high-poverty, urban schools in one district. We analyzed these interviews by drafting thematic summaries, coding interview transcripts, creating data-analytic matrices, and writing analytic memos. Findings: We find that students introduced considerable uncertainty into teachers’ work. Although most teachers we spoke with embraced the challenges of their work and the expanded responsibilities that it entailed, they recognized that their individual efforts were not sufficient to succeed. Teachers consistently spoke about the need for organizational responses that addressed the environmental uncertainty of working with students from low-income families whose experience in school often has been unsuccessful. We describe four types of organizational responses—coordinated instructional supports, systems to promote order and discipline, socioemotional supports for students, and efforts to engage parents—and illustrate how these responses affected teachers’ ability to manage the uncertainty introduced by their environment. Conclusions: Traditional public schools are open systems and require systematic organizational responses to address the uncertainty introduced by their environments. Uncoordinated individual efforts alone are not sufficient to meet the needs of students in high-poverty urban communities.

In-package atmospheric pressure cold plasma treatment of strawberries

The ability to generate low temperature plasma at atmospheric pressure offers new opportunities to decontaminate biological materials, including fresh foods. In this study, strawberries were treated with atmospheric cold plasma (ACP), generated with a 60kV dielectric barrier discharge (DBD) pulsed at 50Hz, across a 40mm electrode gap, generated inside a sealed package containing ambient air (42% relative humidity). The current–voltage characteristics revealed that the plasma operated in the filamentary regime. The background microflora (aerobic mesophillic bacteria, yeast and mould) of strawberries treated for 5min was reduced by 2 log10 within 24h of post-ACP treatment. The respiration rate of ACP treated produce, measured by the closed system approach, showed no significant increase. The effect of ACP on strawberry colour and firmness was insignificant.

Decoherence: A Closed-System Approach

The aim of this paper is to review a new perspective about decoherence, according to which formalisms originally devised to deal just with closed or open systems can be subsumed under a closed-system approach that generalizes the traditional account of the phenomenon. This new viewpoint dissolves certain conceptual difficulties of the orthodox open-system approach but, at the same time, shows that the openness of the quantum system is not the essential ingredient for decoherence, as commonly claimed. Moreover, when the behavior of a decoherent system is described from a closed-system perspective, the account of decoherence turns out to be more general than that supplied by the open-system approach, and the quantum-to-classical transition defines unequivocally the realm of classicality by identifying the observables with classical-like behavior.

Closed system approach to open systems: tunnelling decay of interacting cold bosons in an optical lattice

A Bose–Hubbard Hamiltonian, modelling cold bosons in an optical lattice, is used to simulate the dynamics of interacting open quantum systems as subsystems of a larger, closed system, avoiding complications like the introduction of baths, complex absorbing potentials or absorbing boundaries. The numerically exact unitary dynamics is compared with the effective descriptions of the subsystems based on non-Hermitian Hamiltonians or Lindblad master equations. The validity of popular models with constant decay rates is explicitly analysed for decaying single and double wells. For simplicity, we concentrate on simulations with very small particle numbers (mostly N = 2, 3) and neglect the interaction in parts of the system where this is appropriate. We furthermore present a discrete lattice version of the Siegert approximation method for calculating decay rates.

Creation and Persistence of Chiral Asymmetry in a Microscopically Reversible Molecular Model

Of the numerous mechanisms that have been postulated to explain the origin of biological homochirality, asymmetric autocatalysis coupled with mutual inhibition is often cited as a plausible route to abiotic symmetry breaking. However, in a system closed to mass flow, the constraint of microscopic reversibility ensures that this far-from-equilibrium phenomenon can at best provide a temporary excursion from racemic equilibrium. Comparatively little attention has been paid in the literature to the manner in which such a closed system approaches equilibrium, examining the mechanisms and time scales involved in its transit. We use an elementary lattice model with molecular degrees of freedom, and satisfying microscopic reversibility, to investigate the temporal evolution of stochastic symmetry breaking in a closed system. Numerical investigation of the model's behavior identified conditions under which the system's evolution toward racemic equilibrium becomes extremely slow, allowing for long-time persistence of a symmetry-broken state. Strong mutual inhibition between enantiomers facilitates a "monomer purification" mechanism, in which molecules of the minor enantiomer are rapidly sequestered and a nearly homochiral state persists for long times, even in the presence of significant reverse reaction rates. Simple order of magnitude estimates show that with reasonable physical parameters a symmetry-broken state could persist over geologically relevant time scales.