Natural Systems Research Articles

On the Characterizations of Approach Groups

In this paper, we present several characterizations on approach groups, and ultra-approach groups. In doing so, we first give necessary and sufficient conditions for an approach structure to be compatible with group structure. We show that every ultra-approach group is ultra uniformizable. Secondly, starting with an approach space, and its natural neighborhood system on a group, we characterize the resulting neighborhood approach group. Finally, we show that the category of ultra-approach-Cauchy group is a topological category, and more importantly, we show that the category of ultra-approach -Cauchy groups and the category of strongly normal limit groups are isomorphic.

The gas hydrate system of the western Black Sea Basin

The basin-scale distribution of gas hydrates and methane migration pathways in the western Black Sea remains enigmatic, owing to the region's complex geological history. Characterizing the abundant gas hydrate accumulations across temporal scales poses significant challenges. In this study, we developed and applied a 3D large-scale numerical model to study the formation, development, and fate of natural gas hydrate systems in the western Black Sea sub-basin. Our model enables us to simulate the dynamic evolution of basin geometry and facies distribution over the last 98 million years and under dynamically changing boundary conditions, e.g. due to sea-level changes. Our study estimates the total volume of gas hydrates stored within western Black Sea sediments at ∼14,607 MtC, equivalent to ∼30,073 × 1011 m3 of CH4 (at STP conditions) which is about 5 times higher than average gas hydrate density at continental margins. Our findings reveal three distinct mechanisms driving gas hydrate reservoir formation within the reconstructed sub-basin: gas hydrate recycling zones, chimney-like structure formation, and gas hydrate deposits associated with paleo-deep sea fans. We identified and simulated key controlling parameters, related to methane migration pathways and regional geomorphology, governing each type of hydrate formation. Subsequently, we conduct a detailed analysis of regional gas hydrate systems, focusing on the Dniepr paleo-fan system, the Danube paleo-fan region, multiple offshore locations near Turkey, and the central Black Sea area. Furthermore, we investigate various biogenic methane formation kinetics and their impact on basin-scale methane generation. Our sensitivity studies enable us to predict the optimal temperature range for microbial activity driving methanogenesis in the Black Sea sediments at 30 °C–40 °C. Overall, our study provides a novel understanding and quantitative correlation between methane generation, migration, and storage in the form of gas hydrates on a basin-scale in the western Black Sea.

Research on the flow characteristics of injecting hydrogen into natural gas pipelines and its impact on energy metering

Injecting hydrogen into natural gas pipelines for direct use by end users is an economical and effective method to realize long-distance transportation of hydrogen. However, the density of hydrogen is much lower than natural gas, and it tends to accumulate at the top of the pipeline, resulting in significant different flow characteristics of pure natural gas. Therefore, mixing hydrogen into natural gas pipelines will affect the accuracy of calorific value and flow rate measurement in the existing natural gas metering system. This article studies the flow characteristics of injecting hydrogen into natural gas using a T-shaped pipe and its impact on energy measurement through CFD numerical simulation. The results show that the energy metering equipment should be installed where the gas reaches a uniform mixture and the radial section velocity is centrally symmetrical. Injecting hydrogen with a lower position, and smaller main stream velocity will shorten the distance between the metering pipeline section and the mixing point, but a distance of at least 100 times the pipe diameter is still required. Thus, a mixing process combining a static mixer and flow straightener is proposed, which reduces this distance to within 40 times the pipe diameters.

A Coupled Model of Multiscaled Creep Deformation and Gas Flow for Predicting Gas Depletion Characteristics of Shale Reservoir at the Field Scale

The viscoelastic behavior of shale reservoirs indeed impacts permeability evolution and further gas flow characteristics, which have been experimentally and numerically investigated. However, its impact on the gas depletion profile at the field scale has seldom been addressed. To compensate for this deficiency, we propose a multiscaled viscoelasticity constitutive model, and furthermore, a full reservoir deformation–fluid flow coupled model is formed under the frame of the classical triple-porosity approach. In the proposed approach, a novel friction-based creep model comprising two distinct series of parameters is developed to generate the strain–time profiles for hydraulic fracture and natural fracture systems. Specifically, an equation considering the long-term deformation of hydraulic fracture, represented by the softness of Young’s modulus, is proposed to describe the conductivity evolution of hydraulic fractures. In addition, an effective strain permeability model is employed to replicate the permeability evolution of a natural fracture system considering viscoelasticity. The coupled model was implemented and solved within the framework of COMSOL Multiphysics (Version 5.4). The proposed model was first verified using a series of gas production data collected from the Barnett shale, resulting in good fitting results. Subsequently, a numerical analysis was conducted to investigate the impacts of the newly proposed parameters on the production process. The transient creep stage significantly affects the initial permeability, and its contribution to the permeability evolution remains invariable. Conversely, the second stage controls the long-term permeability evolution, with its dominant role increasing over time. Creep deformation lowers the gas flow rate, and hydraulic fracturing plays a predominant role in the early term, as the viscoelastic behavior of the natural fracture system substantially impacts the long-term gas flow rate. A higher in situ stress and greater formation depth result in significant creep deformation and, therefore, a lower gas flow rate. This work provides a new tool for estimating long-term gas flow rates at the field scale.

Confronting the United Nations’ Pro-growth Agenda

In this article, we enjoin the United Nations (UN) to forge a path out of our plight of multiple environmental and social crises. With other analysts, we identify ‘overshoot’ – the state in which humanity has substantially outpaced Earth’s capacity to regenerate its natural systems and to absorb our waste output – as the root cause of the existential threats we face. This dangerous condition demands rethinking our relationship with Earth and embarking on scaling down the human enterprise within policy frameworks of equity and rights. We argue that when the UN first articulated its international unity and prosperity mission, it did so within a ‘growth’ paradigm that treats Earth and its nonhuman inhabitants as mere resources at humanity’s disposal. The 1994 Cairo Conference on Population and Development reinforced this agenda, with its sharp turn away from the earlier emphasis on population concerns and their link to environmental protection. Today, it is clear that the UN’s foundational goals of peace, human rights and sustainability flounder within a growth-driven framework of human exceptionalism and nature domination. To correct course and reverse our advanced state of ecological overshoot we urge the UN to lead in contracting the large-scale variables of the human enterprise – population, economy, technosphere – and to resist co-optation by political, ideological and special interest pressures that would derail this mandate.

Separation of siderite from calcite by differential reaction with dilute ethanoic acid: mineralogical and isotopic (δ13C, δ18O) effects

ABSTRACT A simple procedure is described for the separation of siderite, from mixtures of siderite and calcite, for carbon and oxygen isotope analysis based on the selective decomposition of calcite by reaction with stoichiometric excess ethanoic acid. Artificial mixtures, prepared from two naturally occurring materials (concretionary siderite containing approximately equal quantities of low-Mg and high-Mg siderite, and low-Mg calcite), are used to test the selectivity of calcite removal, investigate the potential for differential acid decomposition of siderites of differing geochemical composition, and assess the effect of separation procedures on the isotopic composition of recovered carbonate. Acidification results in complete removal of calcite and only minor (< 2 wt %) siderite decomposition. Isotopic effects are limited with minimal difference between untreated (experimental control) and acid-treated materials. Discrepancies are attributed to preferential decomposition (greater reactivity) of (low δ13C, δ18O) high-Mg over (high δ13C, δ18O) low-Mg siderite in moderately acidic solvents. Observed departures from true isotopic compositions are insignificant for most geochemical applications when compared with other sources of uncertainty associated with the interpretation of siderite stable-isotope data sets in natural systems.

Engineered transcription activator-like effector dimer proteins confer DNA loop-dependent gene repression comparable to Lac repressor.

Natural prokaryotic gene repression systems often exploit DNA looping to increase the local concentration of gene repressor proteins at a regulated promoter via contributions from repressor proteins bound at distant sites. Using principles from the Escherichia coli lac operon we design analogous repression systems based on target sequence-programmable Transcription Activator-Like Effector dimer (TALED) proteins. Such engineered switches may be valuable for synthetic biology and therapeutic applications. Previous TALEDs with inducible non-covalent dimerization showed detectable, but limited, DNA loop-based repression due to the repressor protein dimerization equilibrium. Here, we show robust DNA loop-dependent bacterial promoter repression by covalent TALEDs and verify that DNA looping dramatically enhances promoter repression in E. coli. We characterize repression using a thermodynamic model that quantitates this favorable contribution of DNA looping. This analysis unequivocally and quantitatively demonstrates that optimized TALED proteins can drive loop-dependent promoter repression in E. coli comparable to the natural LacI repressor system. This work elucidates key design principles that set the stage for wide application of TALED-dependent DNA loop-based repression of target genes.

Trajectories of socio-ecological systems: Does social capital matter? A case study in the tropical Andes

Between natural and social systems there are two-way interactions, which determine the path of change in the Socio-Ecological System. For example, the type of land use decisions that society makes could lead to the deterioration of the biophysical system and its ecological functioning, causing effects on social well-being. Conceptual and simulation models of socio-ecological systems allow an understanding of such interactions and the development of trajectories. In this manuscript we explore the link between three lines of research that overlap but have been studied separately (i) Governance, (ii) Socio-ecological systems, and (iii) social capital. This paper analyzes the dynamics of social capital and its influence on governance and Land Use and Land Cover Changes in a basin of the Colombian Andes. To this end, we develop a Systems Dynamics model (SD). This research contributes to the (i) understanding of how the institutions, their policies, the actors, and the interactions generated between them in a territory influence the management of natural resources, which is indispensable to supporting the decision-making process; and (ii) operationalization of the social capital elements on the SES model through an integrated analysis with consideration of feedback mechanisms between natural and social system. With this model, a scenario evaluation is developed to analyze the effect of different approaches of the social capital organization on land cover in the basin case study.

Identifying pathways of pharmaceutical exposure in a mesoconsumer marine fish

Pharmaceutical uptake involves processes that vary across aquatic systems and biota. However, single studies examining multiple environmental compartments, microhabitats, biota, and exposure pathways in mesoconsumer fish are sparse. We investigated the pharmaceutical burden in bonefish (Albula vulpes), pathways of exposure, and estimated exposure to a human daily dose. To evaluate exposure pathways, the number and composition of pharmaceuticals across compartments and the bioconcentration in prey and bonefish were assessed. To evaluate bioaccumulation, we proposed the use of a field-derived bioaccumulation factor (fBAF), due to variability inherent to natural systems. Exposure to a human daily dose was based on bonefish daily energetic requirements and consumption rates using pharmaceutical concentrations in prey. Pharmaceutical number and concentration were highest in prey, followed by bonefish, water and sediment. Fifteen pharmaceuticals were detected in common among bonefish, prey, and water; all of which bioconcentrated in prey and bonefish, and four bioaccumulated in bonefish. The composition of detected pharmaceuticals was compartment specific, and prey were most similar to bonefish. Bonefish were exposed to a maximum of 1.2 % of a human daily dose via prey consumption. Results highlight the need for multicompartment assessments of exposure and consideration of prey along with water as a pathway of exposure.

A modular DNA origami nanocompartment for engineering a cell-free, protein unfolding and degradation pathway.

Within the cell, chemical reactions are often confined and organized through a modular architecture. This facilitates the targeted localization of molecular species and their efficient translocation to subsequent sites. Here we present a cell-free nanoscale model that exploits compartmentalization strategies to carry out regulated protein unfolding and degradation. Our synthetic model comprises two connected DNA origami nanocompartments (each measuring 25 nm × 41 nm × 53 nm): one containing the protein unfolding machine, p97, and the other housing the protease chymotrypsin. We achieve the unidirectional immobilization of p97 within the first compartment, establishing a gateway mechanism that controls substrate recruitment, translocation and processing within the second compartment. Our data show that, whereas spatial confinement increases the rate of the individual reactions by up to tenfold, the physical connection of the compartmentalized enzymes into a chimera efficiently couples the two reactions and reduces off-target proteolysis by almost sixfold. Hence, our modular approach may serve as a blueprint for engineering artificial nanofactories with reshaped catalytic performance and functionalities beyond those observed in natural systems.

Performance analysis of the temperature-upgraded flash-driven low-temperature advanced natural circulation heating reactor system

To address the current deficiencies in outlet temperature and thermal power of low-temperature heating reactors while ensuring safety and economic viability, this study introduces the Temperature-Upgraded Flash-driven Low-temperature Advanced Natural Circulation Heating Reactor (TU-FLANC). The FLANC system innovatively utilizes the flashing phenomenon of the coolant in the rising channel to significantly increase the coolant circulation flow rate and thus enhance thermal power at atmospheric pressure. The TU system employs an Absorption Heat Pump (AHP) to upgrade the temperature of the reactor’s output heat. The two systems are interconnected via a Coupled System Heat Exchanger (CSHEX), achieving an upgrade in reactor thermal power and outlet temperature at atmospheric pressure. To evaluate the performance of the TU-FLANC system, a mathematical model of the system was established, and a computational program was developed. The impact of key parameters such as evaporator temperature, condenser temperature, and solution concentration on system performance was analyzed. The results indicate that the evaporator temperature and solution concentration have the most significant impact on the system’s coefficient of performance (COP) and the coefficient of performance considering pump work (COPW). Through Differential Evolution (DE) algorithm optimization, the optimal solution concentration combinations were determined to maximize COP and COPW under different temperature upgrade demands. For a temperature upgrade demand of 50 °C, the optimal solution concentration combinations are 40.02 % and 57.48 %, with corresponding COP and COPW values of 0.5282 and 0.4886, respectively. The research findings highlight the significant innovative potential of the TU-FLANC system in enhancing heat power and outlet temperature.

Privacy Preservation of Large Language Models in the Metaverse Era: Research Frontiers, Categorical Comparisons, and Future Directions

ABSTRACTLarge language models (LLMs), with their billions to trillions of parameters, excel in natural language processing, machine translation, dialog systems, and text summarization. These capabilities are increasingly pivotal in the metaverse, where they can enhance virtual interactions and environments. However, their extensive use, particularly in the metaverse's immersive platforms, raises significant privacy concerns. This paper analyzes existing privacy issues in LLMs, vital for both traditional and metaverse applications, and examines protection techniques across the entire life cycle of these models, from training to user deployment. We delve into cryptography, embedding layer encoding, differential privacy and its variants, and adversarial networks, highlighting their relevance in the metaverse context. Specifically, we explore technologies like homomorphic encryption and secure multiparty computation, which are essential for metaverse security. Our discussion on Gaussian differential privacy, Renyi differential privacy, Edgeworth accounting, and the generation of adversarial samples and loss functions emphasizes their importance in the metaverse's dynamic and interactive environments. Lastly, the paper discusses the current research status and future challenges in the security of LLMs within and beyond the metaverse, emphasizing urgent problems and potential areas for exploration.

Plant-Derived Chinese Herbal Hydrogel Microneedle Patches for Wound Healing.

Several natural Chinese herbal medicines have demonstrated considerable potential in facilitating wound healing, while the primary concern remains centered around optimizing formulation and structure to maximize their efficacy. To address this, a natural microneedles drug delivery system is proposed that harnesses gelatinized starch and key Chinese herbal ingredients-aloe vera and berberine. After gelatinized and aged in a well-designed mold, the starch-based microneedles are fabricated with suitable mechanical strength to load components. The resulting Chinese herbal hydrogel microneedles, enriched with integrated berberine and aloe, exhibit antibacterial, anti-inflammatory, and fibroblast growth-promoting properties, thereby facilitating wound healing in the whole process. In vivo experimental results underscore the notable achievements of the microneedles in early-stage antibacterial effects and subsequent tissue reconstruction, contributing significantly to the overall wound healing process. These results emphasize the advantageous combination of traditional Chinese medicine with microneedles, presenting a novel strategy for wound repair and opening new avenues for the application of traditional Chinese medicine.

Multi-objectives occupant-centric control of thermostats and natural ventilation systems in cold climate conditions using real-time occupant-related information

Recently, Occupant-Centric Controls (OCCs) have attracted great attention. Many studies have applied OCCs to mechanical ventilation systems, while natural ventilation systems have gathered much less attention. The natural ventilation effect, driven by opening windows or vents, can be effective in improving indoor air quality, however, result in a leakage of interior heating energy in winter in cold climates. Therefore, the controls of thermostats and natural ventilation systems shall be designed well so that satisfying levels of thermal comfort, air quality and energy conservation can be simultaneously guaranteed. This study proposes an OCC and applies it to thermostats and natural ventilation systems for indoor thermal comfort, air quality and heating energy management. The strategy comprises three controllers: occupancy-based on-off controller, controller of setpoint of indoor air temperature and window openness controller. First, real-time profiles of heat gains from occupants and window openness were collected by employing vision-based detection. Second, a parametric building simulation study was conducted, and then simulation data were generated to develop predictive shallow artificial neural networks for forecasting the indoor conditions and energy performance of the investigated room. Third, the performance of the proposed strategy was examined. Compared to the baselines, the control could offer a decrease in building heating loads by between 43.4% and 63.8 % and an improvement of predicted mean vote levels by 0.36–0.37. The proposed OCC could also maintain indoor CO2 concentrations below 1000 ppm for about 91 % of the studied time, while 84.2 % of the time with several peaks over 3000 ppm in the baseline cases.

A two-way coupled CHANS model for flood emergency management, with a focus on temporary flood defences

This study presents a novel Coupled Human And Natural Systems (CHANS) modelling framework that integrates a hydrodynamic model with an agent-based model at the memory level within a multi-GPU computing environment. This two-way coupled model captures real-time interactions between human activities and flood dynamics, with a focus on the deployment of temporary flood defences during the 2015 Desmond flood in Carlisle, UK. The findings reveal that temporary defences can significantly reduce flood inundation by 30% with early warnings and 15% through real-time decision-making, leading to financial savings of £30 million and £15 million, respectively. The study further explores the decision-making process for effective emergency flood management, emphasising the importance of early warnings and resources optimisation. The new CHANS model provides a valuable tool for testing and optimising emergency flood management strategies, highlighting the necessity of directly incorporating human activities into flood risk management.

Fertilizer use and agricultural practices in the paradox of maize crop production and environmental sustainability

The enduring existence of pollution presents a substantial danger to human health, natural systems, and social welfare. Human activities mostly generate greenhouse gas emissions, namely carbon dioxide, which negatively impacts the environment. This study used annual datasets to examine the association between maize crop production, maize yield, fertilizer consumption, agricultural land use, and environmental quality in China. In order to identify the positive and negative shocks with the assessment of short- and long-run dynamics, the study used an asymmetric Nonlinear Autoregressive Distributed Lag (NARDL) approach. A Robust Least Squares method was also used to locate the parameters nexus in order to assess the series' robustness. Results from the long-run interaction indicate that the maize crop production and agricultural land use has a positive impact on CO2 emissions with probability values of (0.000), (0.000), and (0.001), (0.780), respectively, via both positive and negative interruptions. Additionally, maize yield exposed a detrimental effect on environmental quality. Results of the robust least squares analysis showed that maize crop production, fertilizer consumption, and agricultural land use had a positive influence on environmental quality, with probability values of (0.000), (0.004), and (0.949), respectively. However, there is an unfavourable relationship between variable maize yields and CO2 emissions. China should play a significant role in seeking to reduce carbon dioxide emissions and adopt the beneficial policies necessary to ensure the environment's long-term sustainability, since these emissions are now a rising issue around the world.

Inferring ecological selection from multidimensional community trait distributions along environmental gradients.

Understanding the drivers of community assembly is critical for predicting the future of biodiversity and ecosystem services. Ecological selection ubiquitously shapes communities by selecting for individuals with the most suitable trait combinations. Detecting selection types on key traits across environmental gradients and over time has the potential to reveal the underlying abiotic and biotic drivers of community dynamics. Here, we present a model-based predictive framework to quantify the multidimensional trait distributions of communities (community trait spaces), which we use to identify ecological selection types shaping communities along environmental gradients. We apply the framework to over 3600 boreal forest understory plant communities with results indicating that directional, stabilizing, and divergent selection all modify community trait distributions and that the selection type acting on individual traits may change over time. Our results provide novel and rare empirical evidence for divergent selection within a natural system. Our approach provides a framework for identifying key traits under selection and facilitates the detection of processes underlying community dynamics.

Atomically precise inorganic helices with a programmable irrational twist.

Helicity in solids often arises from the precise ordering of cooperative intra- and intermolecular interactions unique to natural, organic or molecular systems. This exclusivity limited the realization of helicity and its ensuing properties in dense inorganic solids. Here we report that Ga atoms in GaSeI, a representative III-VI-VII one-dimensional (1D) van der Waals crystal, manifest the rare Boerdijk-Coxeter helix motif. This motif is a non-repeating geometric pattern characterized by 1D face-sharing tetrahedra whose adjacent vertices are rotated by an irrational angle. Using InSeI and GaSeI, we show that the modularity of 1D van der Waals lattices accommodates the systematic twisting of a periodic tetrahelix with a 41 screw axis in InSeI to an infinitely extending Boerdijk-Coxeter helix in GaSeI. GaSeI crystals are non-centrosymmetric, optically active and exfoliable to a single chain. These results present a materials platform towards understanding the origin and physical manifestation of aperiodic helicity in low-dimensional solids.

Thermoregulatory integration in hand prostheses and humanoid robots through blood vessel simulation

In this paper, we introduce an innovative approach for generating robotic faces with a thermal signature similar to that of humans and equipping prosthetic or robotic hands with a lifelike temperature distribution. This approach enhances their detection via infrared cameras and promotes more natural interactions between humans and robots. This method integrates a temperature regulation system into artificial skin, drawing inspiration from the human body’s natural temperature control via blood flow. Central to this technique is a fiber network simulating blood vessels within the artificial skin. Water flows through these fibers under specific temperature and flow conditions, forming a controlled heat release system. The heat emission can be adjusted by changing the dilation of these fibers, primarily by modulating the frequency of circulation. Our findings indicate that this approach can replicate the varied thermal characteristics of different human faces and hand areas. Consequently, the robotic faces appear more human-like in infrared images, aiding their identification by infrared cameras. At the same time, the prosthetic hands achieve a more natural temperature, reducing the discomfort typically felt in direct contact with synthetic limbs. The aim of this study was to address the challenges faced by the users of prosthetic hands. The results from this study show a promising direction in humanoid robotics, fostering improved tactile interactions and redefining human–robot relationships. This innovative technique facilitates further advancements, blurring the lines between artificial aids and natural biological systems.

Artificial magnetosomes: Molecularly restructured SPIONs with enhanced potential for magnetic imaging

Magnetosomes represent an elegant example of ultrastable nanomaterials that nature produces by encapsulating magnetic nanoparticles in liposomal sub-compartments of magnetotactic bacteria. Materials chemists continue to strive for ways to mimic the performance of natural systems, but the artificial synthesis of magnetosomes remains unrealized. Here, we report molecular restructuring of the surface of oleic-acid-capped superparamagnetic iron oxide nanoparticles (SPIONs) to produce magnetosomes. Our strategy involves the use of triethylamine as an amphiphilic surfactant that through a combination of ligand exchange and rearrangement mechanisms, facilitates an organic-to-aqueous phase transfer of SPIONs while turning them into magnetosomes. These liposome-encapsulated SPIONs showed dynamic aqueous stability alongside noticeably improved magnetic properties. This improved their performance as contrast agents for magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), the latter revealing a 33.5 % improvement in signal sensitivity over the original SPIONs. The presented strategy is extendable to prepare liposomal dispersions of other biomedically important nanomaterials.