The emergence of complex adaptive response networks in China: A case study of four disasters

This study aims to identify the driving forces behind interorganizational networks in China following disasters. Using the theory of complex adaptive systems, we identified the self-organization process of disaster response as the network formation process. We identified interorganizational networks that emerged in response to two natural hazards and two technical disasters by collecting data from multiple sources. The exponential random model analysis is performed to analyze the effects of structures and organizational attributes on network formation. In structuring networks for disaster response, findings demonstrate that bonding structures take precedence over bridging structures for organizations. Meanwhile, the sector and jurisdiction-based homophily effects facilitate network formation in disaster response. On the basis of research findings, five propositions describing the network formation process in China's disaster response are proposed. Such a theoretical model is essential for advancing research and practice in complex disaster network management.

A Brief Overview of the Microstructural Engineering of Inorganic-Organic Composite Membranes Derived from Organic Chelating Ligands

This review presents a concise conceptual overview of membranes derived from organic chelating ligands as studied in several works. The authors' approach is from the viewpoint of the classification of membranes by matrix composition. The first part presents composite matrix membranes as a key class of membranes and makes a case for the importance of organic chelating ligands in the formation of inorganic-organic composites. Organic chelating ligands, categorized into network-modifying and network-forming types, are explored in detail in the second part. Four key structural elements, of which organic chelating ligands (as organic modifiers) are one and which also include siloxane networks, transition-metal oxide networks and the polymerization/crosslinking of organic modifiers, form the building blocks of organic chelating ligand-derived inorganic-organic composites. Three and four parts explore microstructural engineering in membranes derived from network-modifying and network-forming ligands, respectively. The final part reviews robust carbon-ceramic composite membranes as important derivatives of inorganic-organic hybrid polymers for selective gas separation under hydrothermal conditions when the proper organic chelating ligand and crosslinking conditions are chosen. This review can serve as inspiration for taking advantage of the wide range of possibilities presented by organic chelating ligands.

Large and stable: actin aster networks formed via entropic forces

Biopolymer networks play a major role as part of the cytoskeleton. They provide stable structures and act as a medium for signal transport. These features encourage the application of such networks as organic computation devices. While research on this topic is not advanced yet, previous results are very promising. The protein actin in particular appears advantageous. It can be arranged to various stable structures and transmit several signals. In this study aster shaped networks were self-assembled via entropic forces by the crowding agent methyl cellulose. These networks are characterised by a regular and uniquely thick bundle structure, but have so far only been accounted in droplets of 100 μm diameter. We report now regular asters in an area of a few mm² that could be observed even after months. Such stability outside of an organism is striking and underlines the great potential actin aster networks display.

Wavelength Orthogonal Photodynamic Networks

The ability of light to remotely control the properties of soft matter materials in a dynamic fashion has fascinated material scientists and photochemists for decades. However, only recently has our ability to map photochemical reactivity in a finely wavelength resolved fashion allowed for different colors of light to independently control the material properties of polymer networks with high precision, driven by monochromatic irradiation enabling orthogonal reaction control. The current concept article highlights the progress in visible light‐induced photochemistry and explores how it has enabled the design of polymer networks with dynamically adjustable properties. We will explore current applications ranging from dynamic hydrogel design to the light‐driven adaptation of 3D printed structures on the macro‐ and micro‐scale. While the alternation of mechanical properties via remote control is largely reality for soft matter materials, we herein propose the next frontiers for adaptive properties, including remote switching between conductive and non‐conductive properties, hydrophobic and hydrophilic surfaces, fluorescent or non‐fluorescent, and cell adhesive vs. cell repellent properties.

Gluten-starch interface characteristics and wheat dough rheology-Insights from hybrid artificial systems

Referring to the total surface existing in wheat dough, gluten-starch interfaces are a major component. However, their impact on dough rheology is largely unclear. Common viewpoints, based on starch surface modifications or reconstitution experiments, failed to show unambiguous relations of interface characteristics and dough rheology. Observing hybrid artificial dough systems with defined particle surface functionalization gives a new perspective. Since surface functionalization standardizes particle-polymer interfaces, the impact on rheology becomes clearly transferable and thus, contributes to a better understanding of gluten-starch interfaces. Based on this perspective, the effect of particle/starch surface functionality is discussed in relation to the rheological properties of natural wheat dough and modified gluten-starch systems. A competitive relation of starch and gluten for intermolecular interactions with the network-forming polymer becomes apparent during network development by adsorption phenomena. This gluten-starch adhesiveness delays the beginning of non-linearity under large deformations, thus contributing to a high deformability of dough. Consequently, starch surface functionality affects the mechanical properties, starting from network formation and ending with the thermal fixation of structure.

Crosslinking Trends in Multicomponent Hydrogels for Biomedical Applications

Multicomponent-based hydrogels are well established candidates for biomedical applications. However, certain aspects of multicomponent systems, e.g., crosslinking, structural binding, network formation, proteins/drug incorporation, etc., are challenging aspects to modern biomedical research. The types of crosslinking and network formation are crucial for the effective combination of multiple component systems. The creation of a complex system in the overall structure and the crosslinking efficiency of different polymeric chains in an organized fashion are crucially important, especially when the materials are for biomedical applications. Therefore, the engineering of hydrogel has to be, succinctly understood, carefully formulated, and expertly designed. The different crosslinking methods in use, hydrogen bonding, electrostatic interaction, coordination bonding, and self-assembly. The formations of double, triple, and multiple networks, are well established. A systematic study of the crosslinking mechanisms in multicomponent systems, in terms of the crosslinking types, network formation, intramolecular bonds between different structural units, and their potentials for biomedical applications, is lacking and therefore, these aspects require investigations. To this end, the present review, focuses on the recent advances in areas of the physical, chemical, and enzymatic crosslinking methods that are often, employed for the designing of multicomponent hydrogels.

DNA Interaction with a Polyelectrolyte Monolayer at Solution-Air Interface

The formation of ordered 2D nanostructures of double stranded DNA molecules at various interfaces attracts more and more focus in medical and engineering research, but the underlying intermolecular interactions still require elucidation. Recently, it has been revealed that mixtures of DNA with a series of hydrophobic cationic polyelectrolytes including poly(N,N-diallyl-N-hexyl-N-methylammonium) chloride (PDAHMAC) form a network of ribbonlike or threadlike aggregates at the solution—air interface. In the present work, we adopt a novel approach to confine the same polyelectrolyte at the solution—air interface by spreading it on a subphase with elevated ionic strength. A suite of techniques–rheology, microscopy, ellipsometry, and spectroscopy–are applied to gain insight into main steps of the adsorption layer formation, which results in non-monotonic kinetic dependencies of various surface properties. A long induction period of the kinetic dependencies after DNA is exposed to the surface film results only if the initial surface pressure corresponds to a quasiplateau region of the compression isotherm of a PDAHMAC monolayer. Despite the different aggregation mechanisms, the micromorphology of the mixed PDAHMAC/DNA does not depend noticeably on the initial surface pressure. The results provide new perspective on nanostructure formation involving nucleic acids building blocks.

Multicomponent Network Formation in Selective Layer of Composite Membrane for CO2 Separation

As a promising material for CO₂/N₂ separation, PolyActive^TM can be used as a separation layer in thin-film composite membranes (TFCM). Prior studies focused on the modification of PolyActive^TM using low-molecular-weight additives. In this study, the effect of chemical crosslinking of reactive end-groups containing additives, forming networks within selective layers of the TFCM, has been studied. In order to understand the influence of a network embedded into a polymer matrix on the properties of the resulting materials, various characterization methods, including Fourier transform infrared spectroscopy (FTIR), gas transport measurements, differential scanning calorimetry (DSC) and atomic force microscopy (AFM), were used. The characterization of the resulting membrane regarding individual gas permeances by an in-house built “pressure increase” facility revealed a twofold increase in CO₂ permeance, with insignificant losses in CO₂/N₂ selectivity.

Impact of Physical Obstacles on the Structural and Effective Connectivity of in silico Neuronal Circuits

Scaffolds and patterned substrates are among the most successful strategies to dictate the connectivity between neurons in culture. Here, we used numerical simulations to investigate the capacity of physical obstacles placed on a flat substrate to shape structural connectivity, and in turn collective dynamics and effective connectivity, in biologically-realistic neuronal networks. We considered μ-sized obstacles placed in mm-sized networks. Three main obstacle shapes were explored, namely crosses, circles and triangles of isosceles profile. They occupied either a small area fraction of the substrate or populated it entirely in a periodic manner. From the point of view of structure, all obstacles promoted short length-scale connections, shifted the in- and out-degree distributions toward lower values, and increased the modularity of the networks. The capacity of obstacles to shape distinct structural traits depended on their density and the ratio between axonal length and substrate diameter. For high densities, different features were triggered depending on obstacle shape, with crosses trapping axons in their vicinity and triangles funneling axons along the reverse direction of their tip. From the point of view of dynamics, obstacles reduced the capacity of networks to spontaneously activate, with triangles in turn strongly dictating the direction of activity propagation. Effective connectivity networks, inferred using transfer entropy, exhibited distinct modular traits, indicating that the presence of obstacles facilitated the formation of local effective microcircuits. Our study illustrates the potential of physical constraints to shape structural blueprints and remodel collective activity, and may guide investigations aimed at mimicking organizational traits of biological neuronal circuits.

The evolution of AGHE as a global leader in education on aging: Why, how, and what's next

The scope of AGHE's responsibility to gerontology and geriatrics extends worldwide, as reflected in its tag line, "Global Leaders in Education on Aging." Optimal responses to worldwide demographic transitions can only come from persons well versed in the dimensions of aging and trained and globally situated to translate that knowledge into effective and culturally appropriate solutions. This article reviews the evolution of AGHE's role in initiating and fostering global networks of educators in gerontology and geriatrics, including collaborative efforts with major international organizations (e.g., WHO, UN, IAGG) to increase the visibility and appreciation of aging-related issues among world leaders; sponsoring national and international meetings and publications to promote the exchange of ideas and refinement of teaching methodologies; initiating and adapting new models of gerontological training enhanced by advances in information and communication technology; and supporting world-wide cohorts of emerging scholars to assume leadership roles within the organization. Recommendations for next steps are considered.

Collision-Free Advertisement Scheduling for IEEE 802.15.4-TSCH Networks

IEEE802.15.4-time slotted channel hopping (TSCH) is a medium access control (MAC) protocol designed to support wireless device networking, offering high reliability and low power consumption, two features that are desirable in the industrial internet of things (IIoT). The formation of an IEEE802.15.4-TSCH network relies on the periodic transmissions of network advertising frames called enhanced beacons (EB). The scheduling of EB transmissions plays a crucial role both in the joining time and in the power consumption of the nodes. The existence of collisions between EB is an important factor that negatively affects the performance. In the worst case, all the neighboring EB transmissions of a node may collide, a phenomenon which we call a full collision. Most of the EB scheduling methods that have been proposed in the literature are fully or partially based on randomness in order to create the EB transmission schedule. In this paper, we initially show that the randomness can lead to a considerable probability of collisions, and, especially, of full collisions. Subsequently, we propose a novel autonomous EB scheduling method that eliminates collisions using a simple technique that does not increase the power consumption. To the best of our knowledge, our proposed method is the first non-centralized EB scheduling method that fully eliminates collisions, and this is guaranteed even if there are mobile nodes. To evaluate our method, we compare our proposal with recent and state-of-the-art non-centralized network-advertisement scheduling methods. Our evaluation does not consider only fixed topology networks, but also networks with mobile nodes, a scenario which has not been examined before. The results of our simulations demonstrate the superiority of our method in terms of joining time and energy consumption.

The Trimerization of Isocyanate-Functionalized Prepolymers: An Effective Method for Synthesizing Well-Defined Polymer Networks

For the study of polymer networks, having access to polymer networks with a controlled and well-defined microscopic network structure is of great importance. However, typically, such networks are difficult to synthesize. In this work, a simple, effective, and widely applicable method is presented for synthesizing polymer networks with a well-defined network structure. This is done by the functionalization of polymeric diols using a diisocyanate, and their subsequent trimerization. Using hexamethylene diisocyanate and hydroxyl-group-terminated poly(ε-caprolactone) and poly(ethylene glycol), it is shown that both hydrophobic and hydrophilic poly(urethane-isocyanurate) networks with a well-defined network structure can readily be synthesized. By using in situ infrared spectroscopy, it is shown that the trimerization of isocyanate endgroups is clearly the predominant reaction pathway of network formation, supporting the proposed mechanism and network structure. The resulting networks possess excellent mechanical properties in both the dry and in the wet state.

Carbonic anhydrase IX is a critical determinant of pulmonary microvascular endothelial cell pH regulation and angiogenesis during acidosis

Carbonic anhydrase IX (CA IX) is highly expressed in rapidly proliferating and highly glycolytic cells, where it serves to enhance acid-regulatory capacity. Pulmonary microvascular endothelial cells (PMVECs) actively utilize aerobic glycolysis and acidify media, whereas pulmonary arterial endothelial cells (PAECs) primarily rely on oxidative phosphorylation and minimally change media pH. Therefore, we hypothesized that CA IX is critical to PMVEC angiogenesis because of its important role in regulating pH. To test this hypothesis, PMVECs and PAECs were isolated from Sprague-Dawley rats. CA IX knockout PMVECs were generated using the CRISPR-Cas9 technique. During serum-stimulated growth, mild acidosis (pH 6.8) did not affect cell counts of PMVECs, but it decreased PAEC cell number. Severe acidosis (pH 6.2) decreased cell counts of PMVECs and elicited an even more pronounced reduction of PAECs. PMVECs had a higher CA IX expression compared with PAECs. CA activity was higher in PMVECs compared with PAECs, and enzyme activity was dependent on the type IX isoform. Pharmacological inhibition and genetic ablation of CA IX caused profound dysregulation of extra- and intracellular pH in PMVECs. Matrigel assays revealed impaired angiogenesis of CA IX knockout PMVECs in acidosis. Lastly, pharmacological CA IX inhibition caused profound cell death in PMVECs, whereas genetic CA IX ablation had little effect on PMVEC cell death in acidosis. Thus CA IX controls PMVEC pH necessary for angiogenesis during acidosis. CA IX may contribute to lung vascular repair during acute lung injury that is accompanied by acidosis within the microenvironment.

Exploring Network Formation of Tough and Biocompatible Thiol-yne Based Photopolymers

This work deals with the in-depth investigation of thiol-yne based network formation and its effect on thermomechanical properties and impact strength. The results show that the bifunctional alkyne monomer di(but-1-yne-4-yl)carbonate (DBC) provides significantly lower cytotoxicity than the comparable acrylate, 1,4-butanediol diacrylate (BDA). Real-time near infrared photorheology measurements reveal that gel formation is shifted to higher conversions for DBC/thiol resins leading to lower shrinkage stress and higher overall monomer conversion than BDA. Glass transition temperature (T_g ), shrinkage stress, as well as network density determined by double quantum solid state NMR, increase proportionally with the thiol functionality. Most importantly, highly cross-linked DBC/dipentaerythritol hexa(3-mercaptopropionate) networks (T_g ≈ 61 °C) provide a 5.3 times higher impact strength than BDA, which is explained by the unique network homogeneity of thiol-yne photopolymers.

Insights into Epoxy Network Nanostructural Heterogeneity Using AFM-IR

The first direct observation of a chemically heterogeneous nanostructure within an epoxy resin is reported. Epoxy resins comprise the matrix component of many high performance composites, coatings and adhesives, yet the molecular network structure that underpins the performance of these industrially essential materials is not well understood. Internal nodular morphologies have repeatedly been reported for epoxy resins analyzed using SEM or AFM, yet the origin of these features remains a contentious subject, and epoxies are still commonly assumed to be chemically homogeneous. Uniquely, in this contribution we use the recently developed AFM-IR technique to eliminate previous differences in interpretation, and establish that nodule features correspond to heterogeneous network connectivity within an epoxy phenolic formulation.

Primary Phenomenon in the Network Formation of Endothelial Cells: Effect of Charge

Blood vessels are essential organs that are involved in the supply of nutrients and oxygen and play an important role in regulating the body's internal environment, including pH, body temperature, and water homeostasis. Many studies have examined the formation of networks of endothelial cells. The results of these studies have revealed that vascular endothelial growth factor (VEGF) affects the interactions of these cells and modulates the network structure. Though almost all previous simulation studies have assumed that the chemoattractant VEGF is present before network formation, vascular endothelial cells secrete VEGF only after the cells bind to the substrate. This suggests VEGF is not essential for vasculogenesis especially at the early stage. Using a simple experiment, we find chain-like structures which last quite longer than it is expected, unless the energetically stable cluster should be compact. Using a purely physical model and simulation, we find that the hydrodynamic interaction retard the compaction of clusters and that the chains are stabilized through the effects of charge. The charge at the surface of the cells affect the interparticle potential, and the resulting repulsive forces prevent the chains from folding. The ions surrounding the cells may also be involved in this process.

Fundamental Principles of Network Formation among Preschool Children

The goal of this research was to investigate the origins of social networks by examining the formation of children's peer relationships in 11 preschool classes throughout the school year. We investigated whether several fundamental processes of relationship formation were evident at this age, including reciprocity, popularity, and triadic closure effects. We expected these mechanisms to change in importance over time as the network crystallizes, allowing more complex structures to evolve from simpler ones in a process we refer to as structural cascading. We analyzed intensive longitudinal observational data of children's interactions using the SIENA actor-based model. We found evidence that reciprocity, popularity, and triadic closure all shaped the formation of preschool children's networks. The influence of reciprocity remained consistent, whereas popularity and triadic closure became increasingly important over the course of the school year. Interactions between age and endogenous network effects were nonsignificant, suggesting that these network formation processes were not moderated by age in this sample of young children. We discuss the implications of our longitudinal network approach and findings for the study of early network developmental processes.