Critical Structural Factors Research Articles

Yin Yang 1 regulates cohesin complex protein SMC3 in mouse hematopoietic stem cells

AbstractYin Yang 1 (YY1) and structural maintenance of chromosomes 3 (SMC3) are 2 critical chromatin structural factors that mediate long-distance enhancer-promoter interactions and promote developmentally regulated changes in chromatin architecture in hematopoietic stem/progenitor cells (HSPCs). Although YY1 has critical functions in promoting hematopoietic stem cell (HSC) self-renewal and maintaining HSC quiescence, SMC3 is required for proper myeloid lineage differentiation. However, many questions remain unanswered regarding how YY1 and SMC3 interact with each other and affect hematopoiesis. We found that YY1 physically interacts with SMC3 and cooccupies with SMC3 at a large cohort of promoters genome wide, and YY1 deficiency deregulates the genetic network governing cell metabolism. YY1 occupies the Smc3 promoter and represses SMC3 expression in HSPCs. Although deletion of 1 Smc3 allele partially restores HSC numbers and quiescence in YY1 knockout mice, Yy1−/−Smc3+/− HSCs fail to reconstitute blood after bone marrow transplant. YY1 regulates HSC metabolic pathways and maintains proper intracellular reactive oxygen species levels in HSCs, and this regulation is independent of the YY1–SMC3 axis. Our results establish a distinct YY1–SMC3 axis and its impact on HSC quiescence and metabolism.

Experiential Learning as a Path to Critical Consciousness in the Medical Curriculum: A Qualitative Study.

Clinical settings are increasingly focused on addressing patients' social needs, thus medical education must prepare future clinicians for this task. Critical consciousness, an awareness that puts health within a broader social, historical, and cultural context, could help shape students' understanding of patient social needs. Our paper explores how experiential learning through participation in a social care intervention deepened students' critical consciousness, or their understanding of the systems and structures that make it difficult for patients to meet their basic needs. We conducted one-on-one semistructured interviews with all 24 students who served as advocates for the intervention. Of the 24 advocates, 75% (n = 18) were first-year medical students, 17% (n = 4) were public health students, and 8% (n = 2) were social work students. Interviews were audiorecorded, transcribed verbatim, and analyzed using framework analysis. We identified themes informed by critical consciousness, including individual (assumptions and biases), interpersonal (communication and relationship), and structural (organization and power) factors. Within these categories, advocates expressed deeper self-awareness of personal biases (individual), the importance of interpersonal communication to build trust with caregivers (interpersonal), and the identification of the structural factors that influence health, such as housing conditions (structural). The advocates highlighted the importance of experiential learning to help them understand social determinants of health. By witnessing multiple patients experiencing social needs, advocates saw the cascading effects of social needs, the structures that make it difficult to meet basic needs, and the effect on health and healthcare behavior. Students engaged in the intervention demonstrated the development of critical consciousness. Although limited, our findings suggest that when students engage with patients around social needs, students can better understand the broader social context of patients' lives. Experiential learning through social care interventions may have the potential to influence critical consciousness development and shape the practice of future clinicians.

Organoids in concert: engineering in vitro models toward enhanced fidelity

AbstractOrganoids have emerged as a powerful platform for studying complex biological processes and diseases in vitro. However, most studies have focused on individual organoids, overlooking the inter‐organ interactions in vivo and limiting the physiological relevance of the models. To address this limitation, the development of a multi‐organoid system has gained considerable attention. This system aims to recapitulate inter‐organ communication and enable the study of complex physiological processes. This review provides a comprehensive overview of the recent advancements in organoid engineering and the emerging strategies for constructing a multi‐organoid system. First, we highlight the critical mechanical, structural, and biochemical factors involved in designing suitable materials for the growth of different organoids. Additionally, we discuss the incorporation of dynamic culture environments to enhance organoid culture and enable inter‐organoid communication. Furthermore, we explore techniques for manipulating organoid morphogenesis and spatial positioning of organoids to establish effective inter‐organoid communication networks. We summarize the achievements in utilizing organoids to recapitulate inter‐organ communication in vitro, including assembloids and microfluidic multi‐organoid platforms. Lastly, we discuss the existing challenges and opportunities in developing a multi‐organoid system from its technical bottlenecks in scalability to its applications toward complex human diseases.

Failure analysis and design improvement of high-pressure seal cone head for vehicle hydrogen engine

As hydrogen energy vehicle technology advances, the performance requirements of vehicle hydrogen engine components become increasingly stringent. The high-pressure sealing cone head is a vital connection of the vehicle's hydrogen engine, however, it is easily fractured during the loading test. To address this issue, this research combines finite element modeling and material characterization methodologies to perform failure analysis and re-optimization design of the sealing cone head. First, the parameters for the CL toughness fracture criteria and the Johnson-Cook constitutive model were obtained by the inversion technique and the tensile test, respectively. On the cold heading formation process of the cone head, finite element analysis and microstructure analysis were performed. The results show that machining defects on the outer surface are the root cause of failure. Fatigue cracking is the main failure mechanism, and the crack gradually expands under the effect of alternating loads, which eventually causes a fracture of the cone head. At the same time, there are bending-type folding defects caused by the instability of the cone head under pressure. Second, the critical structural and process factors that impact the mechanical behavior of the components are investigated, and the orthogonal experiment optimization method is utilized to find the optimal process parameters, using the damage value as the evaluation index. According to the findings, the die angle has a major impact on the damage value, but the eligible die angle that is too small would negatively affect the force of the cone head and nut. Finally, a multi-station cold heading procedure for the high-pressure seal cone head was innovatively presented, and its mechanism of action was unveiled. The aforementioned defects were effectively addressed by the optimized process, and as compared to the pre-optimization, the maximum principal stress of the optimized component in the C-region was reduced by 27%, which did not exceed the tensile strength. At the same time, the spindle load was decreased by 25% and the maximum damage value was decreased by 48%, reaching the safe range. The optimized process effectively improves the performance of the part and increases the quality stability.

Numerical Investigation on the Performance of Horizontal Helical-Coil-Type Backfill Heat Exchangers with Different Configurations in Mine Stopes

The application of ground heat exchanger technology in backfill mines can actualize subterranean heat storage, which is one of the most effective solutions for addressing solar energy faults such as intermittence and fluctuation. This paper provides a 3D unsteady heat transfer numerical model for full-size horizontal backfill heat exchangers (BFHEs) with five configurations in a mining layer of a metal mine by using a COMSOL environment. In order to ensure the fairness of the comparative analysis, the pipes of BFHEs studied have the same heat exchange surface area. By comparing and evaluating the heat storage/release characteristics of BFHEs in continuous operation for three years, it was discovered that the helical pipe with serpentine layout may effectively enhance the performance of BFHEs. Compared with the traditional SS BFHEs, the heat storage capacity of the S-FH type is significantly increased by 21.7%, followed by the SA-FH type, which is increased by 11.1%, while the performances of U-DH and SH type are considerably lowered. Also, the impact of the critical structural factors (pitch length and pitch diameter) was further studied using the normalized parameters C1 and C2 based on the inner diameter of the pipe. It is discovered that BFHEs should be distributed in a pipe with a lower C1, and increasing C2 encourages BFHEs to increase the storaged/released heat of BFHEs. By comparatively analysing the effect of thermal conductivity, it is found that the positive effects of thermal conductivity on the performance of SH, U-DH, SA-FH, and S-FH type BFHEs are found to decrease successively. This work proposes a strategy for improving the heat storage and release potential of BFHEs in terms of optimal pipe arrangement.

Investigation of bread staling by handheld NIR spectroscopy in tandem with 2D-COS and MCR-ALS analysis

The present investigations were carried out using the technique of handheld near-infrared (NIR) spectroscopy for time-dependent diffuse-reflection measurements of the cut face of a fresh baguette. The critical structural factors in the staling process of bread are the crystallization of amylopectin in starch and the decrease of water content by evaporation and diffusion from core to crust. To monitor the synchronicity and sequence of these changes, Two-Dimensional Correlation Spectroscopy (2D-COS) was applied. Due to the significant variation of spectral changes at different stages of the aging process, the spectra were split into two sets of 0 – 6/6 – 48 hr. 2D-COS analysis allowed to differentiate the detailed sequence of the following structural events for these time intervals: crystallization of amylopectin/evaporation of weakly and strongly hydrogen-bonded water/reorganization of starch OH-functionalities. Furthermore, Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) was used to investigate the changes in the spectra profile as a function of aging time.

Exploring Problematic Substance use Trajectory in Hong Kong: A Life Course Perspective

The purpose of this study is to take a life course perspective to explore how experiences at different life course stages of substance users and contextual factors influence their drug use behaviors. Using the life history narrative approach to interview 31 persons who were taking part in rehabilitation treatment in Hong Kong, this study maps out substance use trajectory into four stages (onset, persistence, escalation, and desistance) addressing three interrelated themes: (1) substance use behavior characteristics, (2) critical life events, (3) and social and structural factors. The results showed an interaction between substance use behaviors and their experience in different life stages. Because substance use has become more hidden in the stage of persistence and escalation, particularly in dense cities like Hong Kong, early social support is advocated to be provided in prevention and rehabilitation, such as offering better vocational training support and follow-up service to rebuild relationships with families.

Machine learning analysis on critical structural factors of Al:ZnO (AZO) films

Machine learning (ML) has been recently approved to generalize materials design insights from many narrow-scoped individual experiments. In this study, decision tree algorithm (DT) was able to clarify critical structural factors enabling Al-doped ZnO (AZO) films with wider (or narrower) energy band gap and higher (or lower) electrical resistivity on published literature data as well as having ∼90 % average prediction accuracy. Cost-effective alternative of expensive physical models and simulations to reveal promising AZO films before physical experiments. Trained DTs were interpreted to uncover critical design insights. It was concluded that all microstructural features (crystalline size, crystallinity, dislocation density and interlamellar spacing) should be considered simultaneously through a holistic perspective in a design proposal. Al doping concentration and film thickness, as charge carrier contributors, were found as critical features for band gap and electrical resistivity, respectively. Effects on microstructural features should be considered as well as prerequisite in film design because of complex crystal growth mechanism.

Manipulating the mechanical properties of cis-polyisoprene nanocomposites via molecular dynamics simulation

Attributed to the reinforcing effect of the NPs, filled natural rubber (NR) exhibits more excellent mechanical properties compared to pure natural rubber and has been attracting considerable scientific and technological attention. However, only a few studies have shown a systematical understanding of the structure-mechanics relation of filled natural rubber. Herein, a common strategy used to study the effects of the critical structural factors on strain-induced crystallization (SIC) and mechanical properties at the molecular level is to adopt molecular dynamic simulation (MD). Increasing the cross-linkage of the polymer matrix improves the entanglement degree, and the mechanical properties are reinforced by the high orientation of the polymer chains due to the high entanglement degree and the dissipation of energy due to the unentangling. Surprisingly, we find that the stress-strain behaviour of filled natural rubber is significantly manipulated by nanoparticle (NP) content, size and strength of interfacial interaction, evidenced by the increase of the chain orientation, SIC, and energy dissipated by NPs and polymer matrix, compared with the case of pure natural rubber. The underlying mechanism is the adsorption of the polymer by NPs, which leads to the orientation and crystallization of the polymer chains induced by NPs during the deformation process and energy dissipation through the slip of NPs and polymer chains. In general, this work demonstrates a detailed molecular-level structure-mechanics relation of filled natural rubber and provides some rational guidelines for experimentally designing and fabricating high-performance elastomer nanocomposites.

Unraveling the dynamic changes of high-speed rail network with urban development: Evidence from China

Previous studies have used complex network theory to examine the characteristics of China's High-Speed Rail (HSR). Nevertheless, little attention is paid to China's HSR network's dynamic evolution and the coevolution of node attributes and embedded structural characteristics. Our study builds China's HSR network using a complex network approach and spatial analysis technique to address this issue. Additionally, we employ a stochastic actor-oriented model (SAOM) to properly decompose the three types of effects on the generation of China's HSR network (i.e., network structure, attribute-based similarity, and exogenous control variables). This study discusses the underlying hypotheses and indicates that 3-cycles is a critical structural factor for the formation of China's HSR network. In terms of the effects of attribute-based similarity, cities with similar Gross Domestic Product (GDP) and geographical proximity are essential nodal drivers for the evolution of the HSR network. Notably, the administrative rank of cities exhibits a significantly negative driving force and a alter effect. These findings shed light on the interactive process of urban regional development and the dynamic evolution of the HSR network, assisting the central and local governments in enacting and implementing appropriate HSR planning policies, ultimately achieving effective urban planning and management.

Characterization of solid-electrolyte/active-material composite particles with different surface morphologies for all-solid-state batteries

In all-solid-state lithium-ion batteries (ASS-LIBs), the electrode structure is an important factor that determines the battery performance; in particular, the formation of contact interface between the active material (AM) and solid electrolyte (SE) is an important issue associated with ASS-LIBs. Although we previously reported the formation of interfacial contacts between AM and SE by dry coating, the influence of the surface morphologies of composite particles on the performance of ASS-LIB was not revealed. In this study, we investigated the effects of the surface morphologies of composite particles on the performance of ASS-LIB. The surface morphologies of composite particles changed from “discrete” to “continuous” as the dry coating progressed. The cell prepared with composite particles showed higher ionic conductivity due to well-percolated ionic path than that prepared with simple mixture. Comparing the composite particles with different surface morphologies, the cell prepared with discrete-coating particles showed lower internal resistance due to higher ionic/electrical conductivity than that prepared with continuous-coating particles. Further, the cells prepared with discrete- and continuous-coating particles showed the highest charge and discharge capabilities, respectively. The results suggest that the contact areas of AM-SE and AM-AM were critical structural factors for the discharge and charge rate capability, respectively.

A novel phthalazinone-based epoxy resin with excellent rheological property and intrinsic flame retardancy

Phthalazinone is a critical structural factor for high-performance polymer material, which is achieved by polar structure and the structure characteristic of unsymmetrical and kink non-coplanar. In this study, a novel phthalazinone-based epoxy (EEPZ) has been designed and synthesized. The rheological behaviors, thermal stability and combustion behaviors of cured systems have been investigated by dynamic rheology, TGA, DMA, UL-94 vertical burning and cone calorimetry tests. It was found that the phthalazinone-based EEPZ epoxy resin had the lower melting viscosity within broader processing window and enhanced char forming ability for bisphenol A epoxy/4′4-diamino-diphenyl sulfone (E44/DDS) system. When combined with only 20 wt% EEPZ in the E44 system, the E44/20%EEPZ/DDS, passed the UL-94 V-0 rating. In the combustion test, the total heat release, total smoke production and peak of heat release rate were sharply respectively decreased by 44.7%, 24.3% and 44.6% in the case of E44/20%EEPZ/DDS compared with E44/DDS. The results of morphology characterization chemical structure and component for residue char in EEPZ epoxy resin confirmed that the phthalazinone group can lead to form nitrogen-containing compact char layer during combustion. The combined technologies (TGA-FTIR, Py-GC/MS) was utilized to detect the pyrolysis process of the crosslinks system and the charring mechanism. Simultaneously, the tensile strength and tensile modulus of the composites were also improved.

The Indivisible Hand of Peace? Consumption Opportunities and Civil War

ABSTRACT GDP is one of the most robust indicators of civil war onset. As debate continues over the mechanisms underlying the relationship between economic development and civil war, this paper scrutinizes the indicator of GDP directly, disaggregating it into its constituent components to examine whether their distinct associations with conflict onset can shed some light into the black box. Analysis of the individual correlations allows for identification of the driving force behind the aggregate statistical relationship. With this information to hand, consistency checks can be made with existing theories and a new theory presented in this paper, which draws attention to a critical structural factor that drives the supply of civil war labor, namely the lack of consumption opportunities. This factor increases the likelihood of civil war in less economically developed countries as individuals with low consumption opportunities have little to lose from reordering the economic and political system. Analysis of the correlations between components of GDP and the onset of civil war shows that this new theory is most consistent with the key drivers of the aggregate relationship. The examination also highlights a new indicator, which is arguably preferable to GDP as a measure of this relationship.

Durability of RC Structures against Carbonation-Induced Corrosion under the Impact of Climate Change

The factors associated with concrete carbonation can be classified in three major categories of environmental factors, concrete's internal-structural factors, and construction-operation conditions. Climate change is expected to cause gradual change in many primary environmental factors, which may accelerate reinforcement corrosion in reinforced concrete (RC) structures. Studies show that CO2 concentration in the atmosphere may rise from 379 ppm in 2005 to 1,000 ppm in 2100. Hence, adoption of suitable measures to protect exposed RC members against carbonation-induced corrosion is essential for countering the future environmental effects which, in turn, requires further investigation on the effect of critical structural factors, such as water-cement ratio and cement content in the concrete mix design, and construction-operation factors, such as concrete cover depth and surface protection, on the durability of RC members. In this study, these factors were investigated through Monte Carlo simulation. The results showed that slight adjustments in some structural and operational factors can significantly reduce the risk of corrosion initiation and ultimately improve the durability of concrete members against corrosion. The effect of each parameter on the probability of corrosion initiation during the design life of a RC structure was analyzed and interpreted using numerical examples.

Modular Assembly of Tunable Fluorescent Chemosensors Selective for Pb2+ and Cu2+ Metal Ions via the Multicomponent Castagnoli‐Cushman Reaction

AbstractThe multicomponent Castagnoli‐Cushman reaction followed by post‐condensational modifications allowed for a flexible, modular construction of fluorescent chemosensor compounds. When tested against a panel of fourteen metal ions, one of the eight compounds investigated in this work was found to selectively respond to Cu2+ ions by fluorescence quenching (thus being a “turn‐off” chemosensor for this metal). Another compound was found to produce fluorescence increase in response to Pb2+ ions. Interestingly, the sensitivity of this “turn‐on” chemosensor to lead(II) ions was unaffected by the presence of a large excess of other metals. Analysis of the structure‐sensing property relationships of these sensors allowed developing a general understanding of the factors influencing the chemosensor properties. All of the critical structural factors employed in the chemosensor design were found to be important for the metal sensing and selectivity. These findings will allow designing next‐generation chemosensors based on the same modular construction approach in the future.

Molecular mechanism of acetoacetyl-CoA enhanced kinetics for increased bioplastic production from Cupriavidus necator 428

Polyhydroxyalkanoates are gaining importance due to their biodegradable nature and close analogy to plastics. Polyhydroxybutyrate (PHB) is the most widely used bioplastic from polyalkanoate family, which is produced by a legion of bacterial species via phbCAB operon encoding β-ketothiolase (PhaA), NADPH-dependent acetoacetyl-coenzyme A (acetoacetyl-CoA) reductase (PhaB) and polyhydroxyalkanoate synthase (PhaC). Augmentation in the activity of these enzymes is promising for increased PHB production which is achieved by enzyme engineering strategies including non-structural and structural approaches. Our study is deployed on directed evolution-based experimentally reported mutants of PhaB enzyme with increased efficiency due to impact on critical structural factors. We have analyzed and compared the native PhaB with two of its variants Q47L and T173S in complex with their cofactor i.e. NADPH as well as the substrate i.e. acetoacetyl-CoA, via long range molecular dynamics simulations. Interaction profile, MMPBSA, essential dynamics, and free energy landscape analysis revealed that the enzyme efficiency is critically affected by cofactor interactions. It was also observed that mutants have higher equilibrium constant with lesser but optimal affinity for substrate and cofactor than the wild type, which might be the reason for increased efficiency of the mutants via enhanced substrate and cofactor exchange rate. Our study provides insights into the cofactor and substrate binding affinities to PhaB enzyme at atomistic level, which will facilitate designing of highly efficient PhaB enzymes for increased PHB production. Communicated by Ramaswamy H. Sarma

Do natural resources impede renewable energy production in the EU? A mixed-methods analysis

Since signing the Amsterdam Treaty in 1997, the European Union (EU) has been working on increasing its renewable energy supply. However, the progress has been uneven across member states. A vibrant literature advances several explanations for this variation, but pays insufficient attention to a critical structural factor – varying levels of natural resource wealth across the EU – and provides an incomplete account by focusing on consumption indicators. Reconciling divergent views in the literature in a single framework, we hold that while overall natural resource abundance can be conducive to renewable energy production within a country, specific natural resources, such as petroleum, are likely to be harmful. These hypotheses find empirical support in a mixed-methods study that combines a fixed-effects statistical analysis of comprehensive panel data between 1997 and 2015 with a comparative qualitative case study of the Netherlands and Belgium. The findings suggest that to achieve the ambitious goals on renewable energy deployment, the EU needs additional policies that explicitly tackle pernicious effects of specific natural resources, including rent-capturing by politicians, rent-seeking by corporate vested interests, and lack of economic incentives to diversify.

Do Natural Resources Impede Renewable Energy Production in the EU? A Mixed-Methods Analysis

Since signing the Amsterdam Treaty in 1997, the European Union (EU) has been working on increasing its renewable energy supply. However, the progress has been uneven across member states. A vibrant literature advances several explanations for this variation, but pays insufficient attention to a critical structural factor – varying levels of natural resource wealth across the EU – and provides an incomplete account by focusing on consumption indicators. Reconciling divergent views in the literature in a single framework, we hold that while overall natural resource abundance can be conducive to renewable energy production within a country, specific natural resources, such as petroleum, are likely to be harmful. These hypotheses find empirical support in a mixed-methods study that combines a fixed-effects statistical analysis of comprehensive panel data between 1997 and 2015 with a comparative qualitative case study of the Netherlands and Belgium. The findings suggest that to achieve the ambitious goals on renewable energy deployment, the EU needs additional policies that explicitly tackle pernicious effects of specific natural resources, including rent-capturing by politicians, rent-seeking by corporate vested interests, and lack of economic incentives to diversify.

New application for aromatic Schiff base: High efficient flame-retardant and anti-dripping action for polyesters

Bonding aryl groups with carbon-nitrogen double bond is a critical structural factor for the self-crosslinking of Schiff bases at high temperature. In this study, a novel aromatic Schiff base “5-(benzylidene-amino)-isophthalic acid dimethyl ester (BA)” has been designed as a self-crosslinking monomer for poly(ethylene terephthalate) (PET) based copolyesters (BAnPETs). The cross-linking behaviors, flame retardancy and non-dripping performance of BAnPETs have been investigated by simultaneous thermal analysis (TG-DSC), dynamic rheology, limiting oxygen index (LOI), UL-94 vertical burning and cone calorimetry tests. It is found that BA units can cross-link during combustion resulting in high melting viscosity and enhance char forming for BAnPETs, which endows the copolyesters with excellent flame retardancy and non-dripping behavior. Incorporating of BA with a low content (only 7.7 mol%), the LOI value of copolyester increases from 22.0% to 31.0%, and at the same time it achieves V-0 rating in the UL-94 vertical burning test. The mode action of Schiff bases on flame retardation and anti-dripping of copolyesters also has been investigated, and the results show that the aromatic Schiff base groups can lead copolyesters to form nitrogen-containing cross-linkable networks and further transform into compact char layer during combustion. The char layer which acts as an effective barrier, cuts off oxygen, hinders the volatilization of combustible gas and isolates unburned polymer from fire resource. This work suggests that using Schiff base as a self-crosslinkable monomer is a new and effective way for fire-safe polymeric materials.

On the forbidden and the optimum crystallographic variant of rutile in garnet

In many inclusion–host systems with similar oxygen packing schemes, the optimum crystallographic orientation relationship (COR) between the inclusion and the host is mostly determined by matching the similar oxygen sublattices of the two structures. In contrast, the prediction of the optimum COR or even just the rationalization of the observed COR(s) between an inclusion and host with incompatible oxygen sublattices, like rutile–garnet, is not straightforward. The related documentation for such cases is therefore limited. Given the abundant crystallographic data for the rutile–garnet system acquired by transmission electron microscopy and electron backscatter diffraction methods recently, this problem can now be examined in detail for the critical structural factors dictating the selection of optimum COR in such a structurally complicated system. On the basis of the unconstrained three-dimensional lattice point match and structural polyhedron match calculated for the observed CORs, it becomes clear that the prerequisite of optimum COR for rutile (rt) in garnet (grt) is to have most of their octahedra similarly oriented/inclined in space by aligning 〈103〉rt and 〈111〉grt for needle extension growth. Further rotation along the 〈103〉rt//〈111〉grt direction then leads to the energetically most favorable COR-2 variant with a good lattice point match defined by the coincidence site lattice (CSL) and a good topotaxial match of the constituent polyhedra at the CSL points, leaving unfavorable COR-1′ in the forbidden zones. This understanding sheds light not only on hierarchical energetics for the selection of inclusion variants in a complicated inclusion–host system, but also on yet-to-be-explored [UVW]-specific CORs and hetero-tilt boundaries for composite materials in general.