Positive Feedback Effect Research Articles

Synergetic Development Measure of Airport Groups Composite System and Its Influencing Factors Analysis: Some Evidence from China

Whether airport groups develop synergistically has become a concern for the aviation industry. Existing studies have neglected the dynamic comprehensive evaluation and analysis of influencing factors of synergy degree. Taking the synergistic development of airport groups as the research perspective, we integrate the dynamic comprehensive evaluation model into the traditional synergy model. From two dimensions of airport development and regional economy, we measured the static synergy degree of the Chengdu-Chongqing airport group and the dynamic synergetic development degree on the overall time series. Further, using a spatial econometric model, we construct a distance economy-nested spatial weight matrix so as to explore the influence of each indicator on the synergy degree of the composite system. The results show that the overall synergy of the Chengdu-Chongqing airport group is above 0.5 in terms of static synergy degree. The clustering spectrum shows that the Chengdu-Chongqing airport group can be divided into three categories and basically forms the characteristic of “two main and multiple auxiliary airports.” In terms of dynamic synergetic development degree and comprehensive evaluation value, the change speed of synergy degree is relatively smooth in the early stage and fluctuates in the later stage, and the overall dynamic evaluation value of the Chongqing regional airports is high. The effects of the explanatory variables of the airport group composite system on the synergy degree show more direct effects than spillover effects, and the direct effects are all positive feedback effects, while the negative spillover effects of the explanatory variables cannot be ignored.

Climate transition over the past two centuries revealed by lake Ebinur in Xinjiang, northwest China

Global climate has undergone dramatic changes over the past 200 years, accurately identifying the climate transition (from LIA to 20th century warming) and its controlling factors will help to address the risks posed by global warming. Detailed analyses of chronology, grain size, color reflectance (L*, a*) and carbon content (TOC, TIC) were conducted on a 200-year sedimentary record from lake Ebinur in Xinjiang, northwest China. The results show that lake sediments are mainly transported by wind, and there are two kinds of different sources and transport processes. Comparative analysis of multi-proxies reveals that the climate transition took place in 1920 AD. In the early period (1816–1920 AD), the high C values indicate strong transport dynamics; the high proportion of ultrafine component indicates strong pedogenesis, combined with high TOC and a* values, it is inferred that the climate is cold and wet. In the later period (1920–2019 AD), the proxies show opposite changes, which may reveal a warm and dry climate. Based on a comprehensive analysis of multi-drivers, we propose that the increase of solar irradiance played a dominant role in 1920 AD climate transition, and the gradual rise in the concentrations of greenhouse gases may have a positive feedback effect.

On Gas Desorption-Diffusion Regularity of Bituminous Coal with Different Particle Sizes and Its Influence on Outburst-Coal Breaking

Coal and gas outburst is an urgent and constantly perplexing problem with coal resource extraction, threatening coal mine safe and sustainable production severely. Its mechanism and the participation of gas in coal breaking are still unclear. To explore this problem, in this paper, gas desorption-diffusion regularity of bituminous coal with different particle sizes and its influence on outburst-coal breaking were investigated through mercury intrusion porosimetry (MIP) tests, isothermal adsorption tests, and desorption-diffusion tests for coal particles with different sizes. The results indicated that the cumulative diffusion amount (Qt) and rate (Qt/Q∞), the effective diffusion coefficient (D′), and the kinetic diffusion parameter (υ) decreased as particle size increased. That meant gas was easier to desorb and diffuse from the smaller coal blocks, consequently making coal break into more tiny particles and accelerating gas desorption. As a result, a positive feedback effect that coal breaks continuously and gas releases rapidly and abundantly was formed in a short time when outbursts started, which caused gas release in quantities and promoted the occurrence of outbursts. The findings of this study enhance our understanding of the mechanism of gas participating in coal fragmentation during outbursts, which are significantly conducive to the prevention and control of coal mine disasters and sustainable production of coal resources.

Is Approximation of an Ideal Defensible?

What role does our knowledge about the ideal society play in guiding policymaking in the real world? One intuitive answer is to approximate. Namely, we have a duty to approximate the ideal within the relevant constraints of feasibility. However, political philosophers seem to have what might be called ‘approximatophobia'. Many philosophers, including idealists such as David Estlund, warn against approximation. Their criticism is chiefly motivated by ‘the problem of second best’, which points out that your second-best option may not be closest to your best option. This paper aims to dispel ‘approximatophobia'. The difficulty posed by the problem of second best is often overstated. More positively, I present a novel defence of approximation, arguing that approximation of an ideal can be a reasonably reliable default strategy of action guidance in the real world. Difficulties that may afflict the project of approximation can be mitigated by sophistication of the project of approximation. After showing that critics of approximation overstep their mark in issuing the strong or moderate warning against approximation, I propose an account of sophisticated approximation. It seeks a series of reforms that make existing social institutions closer to the ideal based on careful selection of frame of analysis. Three virtuous correlations are identified as indicators for successful project of approximation, linking descriptive similarity to desirability, feasibility and knowledge of the ideal. I also explain a two-staged strategy of sophisticating the way you approximate the ideal, with an expected positive feedback effect.

The effect of positive and negative evaluation on state anxiety and repetitive negative thinking in social evaluative situations: An experimental study

The Bivalent Fear of Evaluation (BFOE) Model suggests that fears of negative and positive evaluation are core cognitive vulnerability and maintenance factors for social anxiety disorder The aim of this study was to experimentally assess cognitive and emotional effects of positive and negative feedback in social anxiety. False positive or negative feedback (vs no feedback) was provided following a speech task to high and low socially anxious individuals to investigate impacts on state anxiety and repetitive negative thinking (N = 152, Mage = 22.13, 69 % female). Measures were completed prior to the speech and after the false feedback but prior to an anticipated discussion with the group about participants’ feedback and performance. High socially anxious participants reporting higher state anxiety and repetitive negative thinking than low socially anxious participants. There were no feedback type by group interactions, indicating that high socially anxious individuals experienced heightened social anxiety and repetitive negative thinking regardless of feedback type (or the absence of feedback). Exploratory analyses revealed that state fear of negative evaluation but not state fear of positive evaluation uniquely predicted both outcomes. Implications for theory and clinical practice are discussed.

Differential regulation of Kiss1 gene expression by oestradiol in the hypothalamus of the female Damaraland mole-rat, an induced ovulator

Kisspeptin, a product of the Kiss1 gene is considered a potent stimulator of gonadotropin release, by interacting with its receptor, the G protein-coupled receptor 54. Kiss1 neurons are known to mediate the positive and negative feedback effects of oestradiol on GnRH neurons that control the pulsatile and surge secretion of GnRH. While in spontaneously ovulating mammals the GnRH/LH surge is initiated by a rise in ovarian oestradiol secreted from maturing follicles, in induced ovulators, the primary trigger is the mating stimulus. Damaraland mole rats (Fukomys damarensis) are cooperatively breeding, subterranean rodents that exhibit induced ovulation. We have previously described in this species the distribution and differential expression pattern of Kiss1-expressing neurons in the hypothalamus of males and females. Here we examine whether oestradiol (E2) regulates the hypothalamic Kiss1 expression in a similar way as described for spontaneously ovulating rodent species. By means of in situ hybridisation, we measured Kiss1 mRNA among groups of ovary-intact, ovariectomized (OVX) and OVX females treated with E2 (OVX + E2). In the arcuate nucleus (ARC), Kiss1 expression increased after ovariectomy and decreased with E2 treatment. In the preoptic region, Kiss1 expression after gonadectomy was similar to the level of wild-caught gonad-intact controls, but was dramatically upregulated with E2 treatment. The data suggest that, similar to other species, Kiss1 neurons in the ARC, which are inhibited by E2, play a role in the negative feedback control on GnRH release. The exact role of the Kiss1 neuron population in the preoptic region, which is stimulated by E2, remains to be determined.

Cyanobacterial organic matter (COM) positive feedback aggravates lake eutrophication by changing the phosphorus release characteristics of sediments

Phosphorus is a key nutrient that causes eutrophication in lakes. Our investigation of 11 eutrophic lakes found that the concentrations of soluble reactive phosphorus (SRP) in the water column and EPC0 in sediments decreased with aggravated eutrophication. There was a significant negative correlation between the SRP concentrations and eutrophication parameters such as chlorophyll a (Chl-a), total phosphorus (TP) and algal biomass (P < 0.001). In addition, SRP concentrations were significantly affected by EPC0 (P < 0.001), while EPC0 was significantly affected by the content of cyanobacterial organic matter (COM) in sediments (P < 0.001). Based on these findings, we hypothesized that COM can alter the phosphorus release characteristics of sediments, including the phosphorus adsorption parameters of sediment (PAPS) and the phosphorus release rate of sediment (PRRS), thereby stabilizing SRP concentrations at lower levels and rapidly replenishing them when depleted by phytoplankton, which in turn benefits cyanobacteria due to their low SRP adaptation strategies. Simulation experiments were conducted to confirm this hypothesis by adding higher plant OM and COM to sediments. The results showed that all types of OM could significantly increase the maximum phosphorus adsorption capacity (Qmax), but only COM could reduce sediment EPC0 and promote PRRS (P < 0.001). Changes in these parameters (i.e., Qmax, EPC0, and PRRS) resulted in a larger SRP adsorption quantity and faster SRP release rate at low SRP concentrations. This promotes the competitive edge of cyanobacteria due to they have a higher affinity for phosphorus than other algae. As an important component of cyanobacteria, EPS can change the phosphorus release characteristics (i.e., PAPS and PRRS) by reducing sediment particle size and increasing sediment surface functional groups. This study revealed the positive feedback effect of COM accumulation in sediments on lake eutrophication from the perspective of phosphorus release characteristics of sediments, which provides a basic reference for the risk assessment of lake eutrophication.

Implications of the delayed feedback effect on the stability of a SIR epidemic model

A basic mathematical model in epidemiology is the SIR (Susceptible–Infected–Removed) model, which is commonly used to characterize and study the dynamics of the spread of some infectious diseases. In humans, the time scale of a disease can be short and not necessarily fatal, but in some animals (for example, insects) this same short time scale can make the disease fatal if we take into account their life expectancy. In this work, we will see how a positive feedback effect (decrease of the susceptible population at small densities) in a SIR model can cause a qualitative characterization of the dynamics defined by the original SIR model. Finally, we will also show with numerical simulations how a delay in the feedback effect causes very interesting qualitative changes of the system with epidemiological significance.

Abnormal causal connectivity of prefrontal-limbic circuit by structural deficits in drug-naive anxiety disorders

BackgroundStructural and functional deficits in the prefrontal-limbic circuit have been revealed in patients with anxiety disorders. However, the effect of structural abnormalities on causal connectivity within this circuit remains unclear. This study aimed to investigate causal connectivity in the prefrontal-limbic circuit associated with structural deficits in drug-naive patients with generalized anxiety disorder (GAD) and panic disorder (PD) and the changes after treatment. MethodsA total of 64 GAD patients, 54 PD patients and 61 healthy controls (HCs) completed the resting-state magnetic resonance imaging scans at baseline. Among them, 96 patients with anxiety disorders (52 in GAD group and 44 in PD group) completed a 4-week paroxetine treatment. Voxel-based morphometry and Granger causality analysis (GCA) were applied to analyze the data based on the human brainnetome atlas. ResultsPatients with GAD and PD showed decreased gray matter volume (GMV) in the bilateral A24cd subregions of cingulate gyrus. Whole-brain analysis revealed decreased GMV in the left cingulate gyrus in patients with PD. Hence, the left A24cd subregion was selected as a seed. Compared with HCs, unidirectional causal connectivity between the limbic-superior temporal gyrus (STG) temporal pole and the limbic-precentral/middle frontal gyrus was enhanced in patients with GAD and PD (from the left A24cd subregion of cingulate gyrus to the right STG temporal pole, and from the left A24cd subregion of cingulate gyrus to the right precentral/middle frontal gyrus). Compared with patients with PD, the limbic-precuneus unidirectional causal connectivity was enhanced in patients with GAD, and the cerebellum crus1 - limbic connectivity has a positive feedback effect. ConclusionsThe anatomical defects in the left A24cd subregion of cingulate gyrus may partially affect the prefrontal-limbic circuit, and the unidirectional causal effect from the left A24cd subregion to the right STG temporal pole may be an imaging change shared by anxiety disorders. The causal effect of the left A24cd subregion of cingulate gyrus to precuneus might be related to the neurobiology of GAD.

Characterization of antigen-specific CD8+ memory T cell subsets in peripheral blood of patients with multiple sclerosis.

Increasing evidence indicates the importance of CD8+ T cells in autoimmune attack against CNS myelin and axon in multiple sclerosis (MS). Previous research has also discovered that myelin-reactive T cells have memory phenotype functions in MS patients. However, limited evidence is available regarding the role of CD8+ memory T cell subsets in MS. This study aimed to explore potential antigen-specific memory T cell-related biomarkers and their association with disease activity. The myelin oligodendrocyte glycoprotein (MOG)-specific CD8+ memory T cell subsets and their related cytokines (perforin, granzyme B, interferon (IFN)-γ) and negative co-stimulatory molecules (programmed cell death protein 1 (PD-1), T- cell Ig and mucin domain 3 (Tim-3)) were analyzed by flow cytometry and real-time PCR in peripheral blood of patients with relapsing-remitting MS. We found that MS patients had elevated frequency of MOG-specific CD8+ T cells, MOG-specific central memory T cells (TCM), MOG-specific CD8+ effector memory T cells (TEM), and MOG-specific CD8+ terminally differentiated cells (TEMRA); elevated granzyme B expression on MOG-specific CD8+ TCM; and, on MOG-specific CD8+ TEM, elevated granzyme B and reduced PD-1 expression. The Expanded Disability Status Scale score (EDSS) in MS patients was correlated with the frequency of MOG-specific CD8+ TCM, granzyme B expression in CD8+ TCM, and granzyme B and perforin expression on CD8+ TEM, but with reduced PD-1 expression on CD8+ TEM. The dysregulation of antigen-specific CD8+ memory T cell subsets, along with the abnormal expression of their related cytokines and negative co-stimulatory molecules, may reflect an excessive or persistent inflammatory response induced during early stages of the illness. Our findings strongly suggest positive regulatory roles for memory T cell populations in MS pathogenesis, probably via molecular mimicry to trigger or promote abnormal peripheral immune responses. Furthermore, downregulated PD-1 expression may stimulate a positive feedback effect, promoting MS-related inflammatory responses via the interaction of PD-1 ligands. Therefore, these parameters are potential serological biomarkers for predicting disease development in MS.

Numerical dependencies of the galactic dynamo in isolated galaxies with SPH

Simulating and evolving magnetic fields within global galaxy simulations provides a large tangled web of numerical complexity due to the vast amount of physical processes involved. Understanding the numerical dependencies that act on the galactic dynamo is a crucial step in determining what resolution and conditions are required to properly capture the magnetic fields observed in galaxies. Here, we present an extensive study on the numerical dependencies of the galactic dynamo in isolated spiral galaxies using smoothed particle magnetohydrodynamics. We performed 53 isolated spiral galaxy simulations with different initial setups, feedback, resolution, Jeans floor, and dissipation parameters. The results show a strong mean-field dynamo occurring in the spiral-arm region of the disk, likely produced by the classical alpha-omega dynamo or the recently described gravitational instability dynamo. The inclusion of feedback is seen to work in both a destructive and positive fashion for the amplification process. Destructive interference for the amplification occurs due to the breakdown of filament structure in the disk, the increase of turbulent diffusion, and the ejection of magnetic flux from the central plane to the circumgalactic medium. The positive effect of feedback is the increase in vertical motions and the turbulent fountain flows that develop, showing a high dependence on the small-scale vertical structure and the numerical dissipation within the galaxy. Galaxies with an effective dynamo saturate their magnetic energy density at levels between 10 and 30% of the thermal energy density. The density-averaged numerical Prandtl number is found to be below unity throughout the galaxy for all our simulations, with an increasing value with radius. Assuming a turbulent injection length of 1 kpc, the numerical magnetic Reynolds number is within the range of Remag = 10 − 400, indicating that some regions are below the levels required for the small-scale dynamo (Remag, crit = 30 − 2700) to be active.

A trigger-substrate model of student engagement with learning

BACKGROUND: There is much controversy and disagreement about engagement with learning, in its definition, its causes and its effects. The recent APS book on “Technologies in Biomedical and Life Sciences Education” outlines these controversies. AIM: To develop upon previously proposed engagement models by using trigger and substrate interactions between contributory factors in order to explain how causative factors may have minimal or no effects on learning when required coincident factors are absent. METHOD: Trigger-substrate steps include a longer-lasting, undergirding substrate factor as well as a short-lived trigger factor, which together act as the cause for the outcome. RESULTS: The model that we propose has engagement, effort and use of resources resulting from the triggers of teaching and providing resources, with a substrate of internalized motivation and a sense of belonging. Continuing forward, engagement, effort and use of resources is a trigger for learning and other benefits, and these results require a substrate of strategies and preparedness in the student. Learning can lead to both positive and negative feedback effects via assessment, feedback (from instructors and the institution), and emotions, which can act via metacognition, incentives and social reinforcement, and achievement, identification (of the student with the learning and outcomes), and the educational climate. CONCLUSIONS: Trigger-substrate causality may help to clarify the inconsistencies seen in education results between traditional theories based on teaching and more recent theories that have focused on the learner. The research has been funded by Brighton and Sussex Medical School This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Spatial-Temporal Differentiation and Spatial Interaction Effect Analysis of Residents’ Consumption Capacity and Consumption Upgrading in China

To investigate Chinese residents’ consumption capacity and consumption upgrading, this study uses the Moran index, the Dagum Gini coefficient method, and the SPVAR model to analyze the spatial-temporal differentiation and interactions between the two; the entropy method is employed to measure the development level of both factors. As per the results, from 2008 to 2020, the levels of consumption capacity and consumption upgrading have increased rapidly and are distinctly unbalanced, but there is a clear trend of convergence between the developments in each province, and both show spatial agglomeration, mainly in the “high–high” and “low–low” clusters. The “high–high” clusters are primarily concentrated in the more economically developed eastern coastal and central fast-rising regions, with inter-regional differences being the main reason for the regional differences between the two. In terms of spatial interaction, the two are Granger causalities, with positive feedback effects that promote each other, and have a “center–periphery” spatial spillover effect, where the center generates spatial spillover and also suffers reverse shocks from the periphery, while the shock effect is limited by inter-provincial economic ties and geographical distance.

Role of Prednisolone in Platelet Activation by Inhibiting TxA2 Generation through the Regulation of cPLA2 Phosphorylation.

Glucocorticoids have been commonly used in the treatment of inflammation and immune-mediated diseases in human beings and small animals such as cats and dogs. However, excessive use can lead to Cushing's syndrome along with several thrombotic and cardiovascular diseases. Although it is well-known that glucocorticoids exert a significant effect on coagulation, the effect of cortisol on platelet function is much less clear. Thus, we aimed to study the effects of prednisolone, one of the commonly used glucocorticoids, on the regulation of platelet function using murine platelets. We first evaluated the concentration-dependent effect of prednisolone on 2-MeSADP-induced platelet function and found that the 2-MeSADP-induced secondary wave of aggregation and dense granule secretion were completely inhibited from 500 nM prednisolone. Since 2-MeSADP-induced secretion and the resultant secondary wave of aggregation are mediated by TxA2 generation, this result suggested a role of prednisolone in platelet TxA2 generation. Consistently, prednisolone did not affect the 2-MeSADP-induced aggregation in aspirinated platelets, where the secondary wave of aggregation and secretion were blocked by eliminating the contribution of TxA2 generation by aspirin. In addition, thrombin-induced platelet aggregation and secretion were inhibited in the presence of prednisolone by inhibiting the positive-feedback effect of TxA2 generation on platelet function. Furthermore, prednisolone completely inhibited 2-MeSADP-induced TxA2 generation, confirming the role of prednisolone in TxA2 generation. Finally, Western blot analysis revealed that prednisolone significantly inhibited 2-MeSADP-induced cytosolic phospholipase A2 (cPLA2) and ERK phosphorylation in non-aspirinated platelets, while only cPLA2 phosphorylation, but not ERK phosphorylation, was significantly inhibited by prednisolone in aspirinated platelets. In conclusion, prednisolone affects platelet function by the inhibition of TxA2 generation through the regulation of cPLA2 phosphorylation, thereby shedding light on its clinical characterization and treatment efficacy in dogs with hypercortisolism in the future.

Optimal design of phase‐locked loop with frequency‐adaptive prefilter based on the accurate small‐signal model

AbstractFrequency‐adaptive prefilters are widely used in the phase‐locked loop (PLL) to suppress input disturbances. However, the parameters of the PLL and prefilters are often designed separately or based on an inaccurate model. The positive feedback effect introduced by the frequency adaption (FA) is usually ignored, leading to non‐optimal performance. Based on the accurate small‐signal model with a particular focus on the FA, this paper proposes an optimal design method for these advanced PLLs. The PLL based on dual second‐order generalized integrator (DSOGI) is taken as an example to demonstrate the principle. With different gain margins, the optimal damping factors of DSOGI and PLL, as well as the natural frequency of PLL, are obtained using the proposed method. Then the global optimal parameters are obtained by evaluating the settling time and overshoot. The analysis shows that the truly optimal parameters are quite different with those provided in the literature, and the dynamic performance is significantly enhanced without degrading the steady‐state performance. Experimental results are presented to verify the theoretical analysis.

KPNA2 promotes osteosarcoma growth and metastasis in a c-Myc-dependent manner via the hedgehog /GLI1 signaling pathway

Despite recent advances, the poor outcomes in osteosarcoma suggest that novel therapeutic targets are needed. Karyopherin alpha 2 (KPNA2) has been identified as a novel oncogene in many cancers. However, the function of KPNA2 in osteosarcoma and its relative mechanisms remain unclear. Herein, we reported that KPNA2 was highly expressed in osteosarcoma, which contributed to poor survival of patients. Knockdown of KPNA2 significantly suppressed osteosarcoma growth and metastasis in vitro and in vivo. Hedgehog/GLI1 was identified as the key effector pathway of KPNA2 in the study. Mechanistically, KPNA2 acts as a nuclear–cytoplasmic shuttle vehicle to transport c-Myc into the nucleus, where c-Myc binds to the promoter of GLI1 to trigger its expression. Besides, c-Myc can also transcriptionally regulate the expression of KPNA2, thus providing a positive feedback effect to amplify the pro-cancer signal further. In summary, our study revealed that KPNA2 promoted the growth and metastasis of osteosarcoma in a c-Myc-dependent manner via the hedgehog/GLI1 signaling pathway. Targeting KPNA2/c-Myc/GLI1 signal axis might provide a potential therapeutic target for the treatment of osteosarcoma.

Antiplatelet Effect of Daphnetin Is Regulated by cPLA2-Mediated Thromboxane A2 Generation in Mice.

Coumarin derivatives have been recognized for their antithrombotic, anti-inflammatory, and antioxidant properties, and daphnetin is one of the natural coumarin derivatives isolated from Daphne Koreana Nakai. Although the pharmacological value of daphnetin is well documented in diverse biological activities, its antithrombotic effect has not been studied to date. Here, we characterized the role and underlying mechanism of daphnetin in the regulation of platelet activation using murine platelets. In order to check the effect of daphnetin on platelet function, we first measured the effect of daphnetin on platelet aggregation and secretion. Collagen-induced platelet aggregation and dense granule secretion were partially inhibited by daphnetin. Interestingly, 2-MeSADP-induced secondary waves of aggregation and secretion were completely inhibited by daphnetin. It is known that 2-MeSADP-induced secretion and the resultant secondary wave of aggregation are mediated by the positive feedback effect of thromboxane A2 (TxA2) generation, suggesting the important role of daphnetin on TxA2 generation in platelets. Consistently, daphnetin did not affect the 2-MeSADP-induced platelet aggregation in aspirinated platelets where the contribution of TxA2 generation was blocked. Additionally, platelet aggregation and secretion induced by a low concentration of thrombin, which is affected by the positive feedback effect of TxA2 generation, were partially inhibited in the presence of daphnetin. Importantly, 2-MeSADP- and thrombin-induced TxA2 generation was significantly inhibited in the presence of daphnetin, confirming the role of daphnetin on TxA2 generation. Finally, daphnetin significantly inhibited 2-MeSADP-induced cytosolic phospholipase A2 (cPLA2) and ERK phosphorylation in non-aspirinated platelets. Only cPLA2 phosphorylation, not ERK phosphorylation, was significantly inhibited by daphnetin in aspirinated platelets. In conclusion, daphnetin plays a critical role in platelet function by inhibiting TxA2 generation through the regulation of cPLA2 phosphorylation.

Biochar assists phosphate solubilizing bacteria to resist combined Pb and Cd stress by promoting acid secretion and extracellular electron transfer

Microorganisms have difficulty surviving and performing remediation functions in mixed systems with high concentrations of Pb and Cd. Biochar has the potential to assist microorganism remediation as an excellent adsorbent for heavy metals. In this study, pig manure biochar (PMB) was used to assist phosphorus solubilizing bacteria (PSB) to explore the mineralization protection and biofeedback mechanism of biochar on PSB under mixed stress of 1000 mg/L Pb2+ and 500 mg/L Cd2+. The adsorption results showed that the removal of Pb2+ and Cd2+ by PMB+PSB was 148.77% and 72.27% higher than that by PSB. Meanwhile, the non-bioavailable fraction of Cd2+ and acid-soluble fraction of Pb2+ in PMB+PSB were increased by 9% and 3%, respectively. Mineralogical and microbial secretion results confirm that showed that the acidic soluble fraction and non-bioavailable fraction were mostly Pb/Cd-carbonate and Pb/Cd-phosphate. The pore adsorption and precipitation (carbonate) of biochar were able to reduce the exposure of PSB to Pb/Cd and the background stress concentration, thus stimulating the biological positive feedback effect of PSB and forming a microenvironment in the cell periphery. The vesicle detoxification and extracellular polymeric substance protection mechanism of PSB were improved under biochar protection, and the individual size and activity of PSB cells were enhanced. Besides, citric acid release from PSB (28.85% increase) accelerated the dissolution of unstable Cd-carbonate, thereby releasing a large amount of Cd2+ to compete with Pb2+ for PO43-. Thus, the protection of biochar and the positive feedback effect of PSB could reduce the biotoxicity of Cd2+ in the stress system by preferentially forming a stable Cd-phosphate. In addition, the excellent electrical conductivity and organic material adsorption of biochar increased the extracellular electron transport rate of microorganisms, which further accelerated the mineralization and immobilization of Pb2+ and Cd2+, so as to ensure the repair effect of PSB on heavy metals.

R&D cooperation in collaborative consumption of research equipment: An ERGM approach

High-tech research infrastructure is essential for state-of-the-art research, but requires many resources. Relatively weak actors, such as SMEs, cannot secure enough of those. Applying the concept of collaborative consumption via digital platforms, we examine the cooperative behavior of Korean SMEs that share research equipment to overcome their lack of resources. Also, we analyze configurations of a collaborative consumption network using the Exponential Random Graph Model. Network structural factor analysis shows sufficient effects of network positive feedback through cooperative consumption with a variety of popular providers and attributes analysis shows that SMEs frequently engage in collaborative consumption with their counterparts in the same region. This new cooperative model can achieve a virtuous cycle of policies, as it increases the efficiency of research infrastructure, preventing the unnecessary building of new research equipment and enabling relocation of underutilized infrastructure and online reservation of equipment.

Response and Multi-Scenario Prediction of Carbon Storage and Habitat Quality to Land Use in Liaoning Province, China

Liaoning Province, as an old industrial urban agglomeration since the founding of China, is an important link between the Bohai Economic Zone and the Northeast Economic Zone, and it has made great contributions to the economic development of China. The transformation of China’s economy and heavy industrial development have posed great challenges to the long-lasting growth of Liaoning Province. In this study, the driving force of land expansion was detected using the patch-generating land use simulation (PLUS) model in Liaoning Province, and the land situation in 2030 was predicted under natural development, ecological protection, and economic development scenarios. We then further coupled the PLUS model with the integrated valuation of ecosystem services and trade-offs (InVEST) model to explore the spatial autocorrelation and synergistic relationship between carbon storage and habitat quality. The results indicated the following: (1) The total accuracy of the simulation in 2020 using the PLUS model reached 94.16%, and the Kappa coefficient reached 0.9089; therefore, the simulation result was highly reliable. (2) The overall spatial pattern of both carbon storage and habitat quality decreased from the northwest and southeast to the middle, and habitat quality had an impact on carbon storage to a certain extent, with a positive spatial correlation. (3) The ecological protection (EP) scenario was the only development prospect with increasing total carbon storage, which could increase carbon sequestration by approximately 7.83 × 106 Mg/C, and development prospects with optimal habitat quality. (4) Weak trade-off and weak synergy dominated in the 2030 natural development (ND) scenario; most regions showed weak synergy in the ecological protection scenario, spatial heterogeneity became more pronounced in the economic development (ED) scenario, and a strong trade-off and strong synergy emerged in individual regions. The results of the study have a positive feedback effect on establishing an ecological security barrier in Liaoning Province and furthering long-lasting low-carbon urban development.