Competitive Interactions Research Articles

Virulence-Related Genes Expression in Planktonic Mixed Cultures of Candida albicans and Non-Albicans Candida Species

Introduction: Candida albicans is the most common opportunistic pathogen causing fungal infections worldwide, especially in high-risk patients. Its pathogenicity is related to virulence factors gene expression, such as hyphal growth (HWP1), cell adhesion (ALS3), and protease secretion (SAP1) during infection spreading mechanisms. In recent years, an increase in non-albicans Candida infections has been reported, which may present coinfection or competitive interactions with C. albicans, potentially aggravating the patient’s condition. This study aims to evaluate the expression of genes related to virulence factors of C. albicans and non-albicans Candida during planktonic stage. Methods: C. albicans (ATCC MYA-3573) as well as with three clinical strains (C. albicans DCA53, C. tropicalis DCT6, and C. parapsilosis DCP1) isolated from blood samples, were grown in 24-well plates at 37°C for 20 h, either in monocultures or mixed cultures. Quantitative real-time polymerase chain reaction was used to evaluate the expression levels of the genes HWP1, ALS3, and SAP1 in cells collected during the planktonic stage. In addition, hyphal filamentation was observed using a Scanning Electron Microscope. Results: The overexpression of HWP1 and ASL3 genes in mixed growth conditions between C. albicans and non-albicans Candida species suggests a synergistic relationship as well as an increased capacity for hyphal growth and adhesion. In contrast, C. parapsilosis versus C. tropicalis interaction shows an antagonistic relationship during mixed culture, suggesting a decreased virulence profile of C. parapsilosis during initial coinfection with C. tropicalis. Conclusion: The expression of HWP1, ALS3, and SAP1 genes associated with virulence factors varies under competitive conditions among species of the genus Candida during planktonic stage.

High early lactational synchrony within baboon groups predicts increased infant mortality.

Social group composition can have fitness implications for group members by determining opportunities for affiliative and competitive interactions. Female-female competition may be particularly acute when many groupmates have young infants at the same time, with potential consequences for infant survival. Here, we used decades of data on wild baboons (Papio sp.) in Amboseli, Kenya, to examine the effects of 'early lactational synchrony' (here, the proportion of females in a group with an infant <90 days old) on female-female agonistic interactions and infant survival. Because early lactation is an energetically demanding time for mothers and a risky time for infants, we expected early lactational synchrony to produce intensified competition for food and/or male protectors, resulting in more frequent female-female agonistic interactions and high infant mortality. In support of these predictions, we found that the frequency of female-female agonistic interactions increased with increasing early lactational synchrony. Reproductive state affected this relationship: while females in all states (cycling, pregnant, and postpartum amenorrhea) initiated more agonistic interactions when early lactational synchrony was high, only females in postpartum amenorrhea (including, but not limited to, females in early lactation) received more agonistic interactions. Furthermore, while high early lactational synchrony was rare, it strongly predicted infant mortality. This association may result from both aggression among adult females and infanticidal behavior by peripubertal females. These findings provide novel evidence that social dynamics may shape reproductive phenology in a nonseasonal breeder. Specifically, both competition among reproductive females and harassment from nonreproductive females may select against synchronous reproduction.

Cell wall melanin impedes growth of the Cryptococcus neoformans polysaccharide capsule by sequestering calcium

Cryptococcus neoformans has emerged as a frontrunner among deadly fungal pathogens and is particularly life-threatening for many HIV-infected individuals with compromised immunity. Multiple virulence factors contribute to the growth and survival of C. neoformans within the human host, the two most prominent of which are the polysaccharide capsule and melanin. As both of these features are associated with the cell wall, we were interested to explore possible cooperative or competitive interactions between these two virulence factors. Whereas capsule thickness had no effect on the rate at which cells became melanized, build-up of the melanin pigment layer resulted in a concomitant loss of polysaccharide material, leaving melanized cells with significantly thinner capsules than their nonmelanized counterparts. When melanin was provided exogenously to cells in a transwell culture system we observed a similar inhibition of capsule growth and maintenance. Our results show that melanin sequesters calcium thereby limiting its availability to form divalent bridges between polysaccharide subunits required for outer capsule assembly. The decreased ability of melanized cells to incorporate exported polysaccharide into the growing capsule correlated with the amount of shed polysaccharide, which could have profound negative impacts on the host immune response.

Escherichia coli alcohol dehydrogenase YahK is a protein that binds both iron and zinc.

Previous studies have highlighted the catalytic activity of Escherichia coli alcohol dehydrogenase YahK in the presence of coenzyme nicotinamide adenine dinucleotide (NAD) and metal zinc. Notably, competitive interaction between iron and zinc ligands has been shown to influence the catalytic efficiency of several key proteases. This study aims to unravel the intricate mechanisms underlying YahK's catalytic action, with a particular focus on the pivotal roles played by metal ions zinc and iron. The purified YahK protein from E. coli cells cultivated in LB medium was utilized to investigate its metal-binding properties through UV-visible absorption measurements and determination of metal content. Subsequently, the effects of excess zinc and iron on the metal-binding ability and alcohol dehydrogenase activity of the YahK protein were explored using M9 minimal medium. Furthermore, site-directed mutagenesis technology was employed to determine the iron-binding site location within the YahK protein. Polyacrylamide gel electrophoresis was conducted to examine the relationship between iron and zinc with respect to the YahK protein. The study confirmed the presence of iron and zinc in the YahK protein, with the zinc-bound form exhibiting enhanced catalytic activity in alcohol dehydrogenation reactions. Conversely, the presence of iron appears to play a pivotal role in maintaining overall stability of the YahK protein. Furthermore, experimental findings indicate that excessive zinc within M9 minimal medium can competitively bind to iron-binding sites on YahK, thereby augmenting its alcohol dehydrogenase activity. The dynamic binding of YahK to iron and zinc unveils its intricate regulatory mechanism as an alcohol dehydrogenase, thereby highlighting the possible physiological role of YahK in E. coli and its significance in governing cellular metabolic processes. This discovery provides a novel perspective for further investigating the specific impact of metal ion binding on YahK and E. coli cell metabolism.

A Cancer Subpopulation Competition Model Reveals Optimal Levels of Immune Response that Minimize Tumor Size.

Breast cancer is a complex disease with significant phenotypic heterogeneity of cells, even within a single breast tumor. Emerging evidence underscores the significance of intratumoral competition, which can serve as a key contributor to cancer drug resistance, imparting substantial clinical implications. Understanding the competitive dynamics is paramount as it can significantly influence disease progression and treatment outcomes. In the present work, a mathematical model was developed using a system of differential equations to describe the dynamic interactions between two cancer subtypes (each further classified into cancer stem cells and tumor cells) and innate immune cells. The purpose of the model is to comprehensively understand the competitive interactions between the heterogeneous subpopulations. The equilibrium points and stability analysis for each equilibrium point were established. Model simulations showed that the competition between two cancer subtypes directly affects the number of both species. When competition between two cancer subtypes is strong, increasing the immune response rate specific to the more competitive species effectively reduces the tumor size. However, if the competition is relatively weak, an optimal immune response rate is required to minimize the total number of tumor cells. Rates below the optimal level fail to reduce the population of the stronger species, whereas rates above the optimal level can lead to the recurrence of the weaker species. Overall, this model provides insights into breast cancer dynamics and guides the development of effective treatment strategies.

Insight into the dynamic evolution of competitive interaction between chloride and sulphate ions in cement-based systems: Effects on chloride diffusion and binding

The dual attack of chloride and sulphate ions is accompanied by the dynamic competitive interaction, yielding a non-negligible influence on their penetrations. Treating this interaction as a steady behaviour will underestimate the ionic ingress and then, overestimate the lifespan of concrete structures. In this study, the evolution of competitive interaction and the associated effect on the chloride diffusion and binding capacity have been investigated by comparing the exclusive chloride and the combined chloride-sulphate attacks. The experimental results disclose that the competitive interaction displayed a dynamic feature. Specifically, the competitive-induced depressions on chloride diffusion and binding capacity evolved first and then appeared to decay after reaching a threshold. Moreover, this competitive interaction was positively related to the w/c ratio and the environmental SO2-4/Cl- ratio. As the slag dosage increased from 0 % to 50 %, the competitive interaction-induced depression upon the free chloride content decreased steadily. However, the inhibition efficiency of the binding capacity decreased first as the slag dosage increased to 20 % and then, evolved significantly with the further increase through 20 % to 50 %. Furthermore, multifactor models are established with good applicability, to respectively predict the effect of this competitive interaction on the diffusion and binding of chloride ions.

Correction for Silva-Andrade et al., "Using metabolic networks to predict cross-feeding and competition interactions between microorganisms".

Correction for Silva-Andrade et al., "Using metabolic networks to predict cross-feeding and competition interactions between microorganisms".

Impact of Chatbots on Satisfaction and Loyalty in Lima's Telecom Sector

The migration towards digital environments has transformed the expectations of consumers, who now not only look for quality products and services, but also convenience, personalization and efficiency in each interaction with the brand. This change presents significant challenges for companies, as they need to constantly adapt to meet their needs and thus maintain loyalty in a highly competitive market. The pressure to offer added value and maintain customer preference is intensified by the ease with which consumers switch to competitors. which drives companies to innovate and adapt AI such as chatbots, which could be the answer to this challenge. The objective of this research work is to know if the use of chatbots positively influences the satisfaction and perceived loyalty of consumers of telephone services, since in this case the speed, quality of the service and the customer's need for understanding. They are critical and represent a greater challenge to differentiate. The methodology used for this research maintains a quantitative, correlational, non-experimental approach. The type of sampling was non-probabilistic, and the strategy was snowball. The instrument used was a questionnaire with a sample of around 130 consumers in the city of Metropolitan Lima in Peru. The findings suggest that chatbots are not only innovative tools, but also strategic ones for telephone companies seeking to improve customer satisfaction and loyalty. The implementation of appropriate chatbots can transform the customer experience, providing a more agile, personalized and effective service, thus seeing a close relationship between the dimensions of the chatbot with the satisfaction and loyalty perceived in consumers. In a world where these variables are key to business survival, chatbots represent an opportunity to create exceptional experiences. Uncover how cutting-edge AI chatbots are revolutionising customer satisfaction and loyalty in the competitive telephone service industry, offering transformative, personalised, and efficient interactions.

Real-time detection of Tau-381 protein using liquid crystal-based sensors for Alzheimer's disease diagnosis

Tau is a protein found in the central nervous system (CNS) and is involved in stabilizing microtubules in axons. Given the link between Tau levels in the body and Alzheimer's disease (AD), there is a demand for straightforward and precise strategies to detect Tau in body fluids. In this study, we report liquid crystal (LC)-based sensors for the real-time detection of Tau protein, a well-known AD biomarker. The sensor uses a detection method based on the orientation change of the LC because of the competitive biomolecular interaction between Tau and Tau aptamers with the cationic polymer poly-L-lysine (PLL). Tau and its aptamers form stable complexes through electrostatic interactions. Owing to the consumption of the aptamer, the positively charged PLL fails to interact with the aptamer but binds to the negatively charged 1.2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) sodium salt (DOPG). The PLL and DOPG complex alters the orientation of the LC to ensure a planar anchoring of the 4-cyano-4′-pentylbiphenyl (5CB)/aqueous interface; this anchoring intensifies with increasing Tau concentration, thus enabling the observation of a bright optical image. Our LC-based sensor demonstrated a low detection limit of 2.77 pg/mL in phosphate buffered saline (PBS) and 10.86 pg/mL and 19.31 pg/mL in human serum and plasma, respectively. Moreover, it is anticipated to be suitable for point-of-care diagnosis of AD because it does not require specialized analytical equipment and only requires microliters of sample.

Simulating the Competitive Ion Pairing of Hydrated Electrons with Chaotropic Cations.

Experiments show that the absorption spectrum of the hydrated electron (ehyd-) blue-shifts in electrolyte solutions compared with what is seen in pure water. This shift has been assigned to the ehyd-'s competitive ion-pairing interactions with the salt cation relative to the salt anion based on the ions' positions on the Hofmeister series. Remarkably, little work has been done investigating the ehyd-'s behavior when the salts have chaotropic cations, which should greatly change the ion-pairing interactions given that the ehyd- is a champion chaotrope. In this work, we remedy this by using mixed quantum/classical simulations to analyze the behavior of two different models of the ehyd- in aqueous RbF and RbI electrolyte solutions as a function of salt concentration. We find that the magnitude of the salt-induced spectral blue-shift is determined by a combination of the number of chaotropic Rb+ cations near the ehyd- and the number of salt anions near those cations so that the spectrum of the ehyd- directly reflects its local environment. We also find that the use of a soft-cavity ehyd- model predicts stronger competitive interactions with Rb+ relative to I- than a more traditional hard cavity model, leading to different predicted spectral shifts that should provide a way to distinguish between the two models experimentally. Our simulations predict that at the same concentration, salts with chaotropic cations should produce larger spectral blue-shifts than salts with kosmotropic cations. We also found that at high salt concentrations with chaotropic cations, the predicted blue-shift is greater when the salt anion is kosmotropic instead of chaotropic. Our goal is for this work to inspire experimentalists to make such measurements, which will help provide a spectroscopic means to distinguish between simulations models that predict different hydration structures for the ehyd-.

Coexistence of a native and an invasive mussel species across an environmental gradient: Do interactions matter?

Introductions of invasive species are increasing worldwide, potentially threatening biodiversity. Although invasive species often displace native species by outcompeting them, coexistence between native and non-native species is common in diverse communities. A field experiment investigated the interactions between the native mussel Mytilus galloprovincialis and the invasive black pygmy mussel Xenostrobus securis across an environmental salinity gradient in the Ria de Vigo (NW Spain). The salinity gradient strongly affected the physiological responses of both mussel species as well as the competitive interactions between the two species. Mytilus galloprovincialis had a stronger effect on the invader than vice versa. The competition with M. galloprovincialis and the release from predation in certain estuarine areas may in part explain the dynamics of the invader population in the Ría de Vigo. Furthermore, results suggest that the invader may contribute positively to ecosystem functioning by increasing bentho-pelagic coupling, water-column clearance, and biodeposition of organic material in the innermost parts of estuaries, where it reaches large abundances. These areas are likely to promote and maintain the supply of propagules to the outermost parts, as well as favouring secondary spread along the Galician coast.

High-Contrast Thermochromism in Room-Temperature Transparent Layered Perovskite PEA2PbBr4 with a High Temperature-Induced Bandgap Change Rate of 0.8 meV/K.

Two-dimensional organic-inorganic hybrid layered perovskites have emerged as a new generation of optoelectronic materials. However, the thermochromism in organic-inorganic hybrid layered perovskites has been rarely explored in depth. A further understanding of the mechanism is necessary and favorable for the application. Here, transparent centimeter-sized single crystals of the organic-inorganic hybrid layered perovskite (C6H5C2H4NH3)2PbBr4 (PEA2PbBr4) were synthesized using an improved evaporation method. As a typical organic-inorganic hybrid layered perovskite, the PEA2PbBr4 single crystal shows high-contrast and progressive thermochromism exhibiting a change from colorlessness and transparency to lemon yellow in a wide temperature range of 200-450 K. Based on the calculation through the Varshni equation, the temperature-induced bandgap change rate directly associated with the high-contrast thermochromism of PEA2PbBr4 reaching 0.8 meV/K. This value is higher than that of many three-dimensional perovskites and traditional IV-III semiconductors. Furthermore, the temperature-dependent 193 nm photoluminescence spectra suggest that this high temperature-induced bandgap change rate of PEA2PbBr4 is a result of the competitive interaction between lattice thermal expansion and electron-phonon coupling (Fröhlich coupling coefficient ΓLO = 2.215). Based on the characteristics introduced above, PEA2PbBr4 as an organic-inorganic hybrid layered perovskite has a better performance in achieving the balance between high-contrast and high room-temperature transmittance. Therefore, PEA2PbBr4 is a material with great potential in applications like temperature-indicating labels. This work provides valuable insights into the thermochromism of layered perovskites, offering a new material system and approach for developing thermochromic materials with higher sensitivity and efficiency.

Effect of artificially induced microcracks near the rock surface on granite fragmentation performance under heating treatment

Various novel assisted drilling technologies enhance rock fragmentation performance by introducing microcracks on the rock surface to weaken rock strength. However, the quantitative relationship between artificially induced microcracks and rock fragmentation characteristics is not clear. In this study, we induced artificial microcracks of varying degrees on the rock surface through one-dimensional heat conduction. With the aid of the fluorescent resin, we visualized the microcrack patterns and quantitatively assessed the artificially induced microcracks. Subsequently, we performed quasi-static indentation tests on granite samples containing microcracks to establish the quantitative relationship between microcracks and rock fragmentation performance. The results indicate that the release of crystal water within the temperature range of 200 °C–300 °C is the primary factor leading to a significant increase in microcracks. Load drop signals correlate with the propagation of microcracks, including the competitive interactions between mechanically induced microcracks and artificially induced microcracks. Artificially induced microcracks require a certain initial length to continue propagating under mechanical stress, and excessively short microcracks are detrimental to subsequent propagation. A higher density of microcracks implies a more complex microcrack network, facilitating the merging of cracks to form rock chips under smaller mechanical loads. The consistency between the length density and number density of microcracks in influencing the crater parameters reflects their equal importance in affecting rock fragmentation performance. These findings could help determine the extent of rock weakening by artificially induced microcracks and reveal the mechanisms of rock fracture behavior influenced by microcrack, holding significant implications for the optimization of the process parameters of various assisted rock drilling techniques.

Transcriptomics reveal a mechanism of niche defense: two beneficial root endophytes deploy an antimicrobial GH18-CBM5 chitinase to protect their hosts.

Effector secretion is crucial for root endophytes to establish and protect their ecological niche. We used time-resolved transcriptomics to monitor effector gene expression dynamics in two closely related Sebacinales, Serendipita indica and Serendipita vermifera, during symbiosis with three plant species, competition with the phytopathogenic fungus Bipolaris sorokiniana, and cooperation with root-associated bacteria. We observed increased effector gene expression in response to biotic interactions, particularly with plants, indicating their importance in host colonization. Some effectors responded to both plants and microbes, suggesting dual roles in intermicrobial competition and plant-microbe interactions. A subset of putative antimicrobial effectors, including a GH18-CBM5 chitinase, was induced exclusively by microbes. Functional analyses of this chitinase revealed its antimicrobial and plant-protective properties. We conclude that dynamic effector gene expression underpins the ability of Sebacinales to thrive in diverse ecological niches with a single fungal chitinase contributing substantially to niche defense.

Invasive plant species support each other's growth in low-nutrient conditions but compete when nutrients are abundant.

Globally, numerous ecosystems have been co-invaded by multiple exotic plant species that can have competitive or facilitative interactions with each other and with native plants. Invaded ecosystems often exhibit spatial heterogeneity in soil moisture and nutrient levels, with some habitats having more nutrient-rich and moist soils than others. The stress-gradient hypothesis predicts that plants are likely to engage in facilitative interactions when growing in stressful environments, such as nutrient-deficient or water-deficient soils. In contrast, when resources are abundant, competitive interactions between plants should prevail. The invasional meltdown hypothesis proposes that facilitative interactions between invasive species can enhance their establishment and amplify their ecological impact. Considering both hypotheses can offer insights into the complex interactions among invasive and native plants across environmental gradients. However, experimental tests of the effects of soil moisture and nutrient co-limitation on interactions between invasive and native plants at both interspecific and intraspecific levels in light of these hypotheses are lacking. We performed a greenhouse pot experiment in which we cultivated individual focal plants from five congeneric pairs of invasive and native species. Each focal plant was subjected to one of three levels of plant-plant interactions: (1) intraspecific, in which the focal plant was grown with another individual of the same species; (2) interspecific, involving a native and an invasive plant; and (3) interspecific, involving two native or invasive individuals. These plant-plant interaction treatments were fully crossed with two levels of water availability (drought vs. well-watered) and two levels of nutrient supply (low vs. high). Consistent with the stress-gradient and invasional meltdown hypotheses, our findings show that under low-nutrient conditions, the biomass production of invasive focal plants was facilitated by invasive interspecific neighbors. However, under high-nutrient conditions, the biomass production of invasive focal plants was suppressed by invasive interspecific neighbors. When competing with native interspecific neighbors, high-nutrient conditions similarly enhanced the biomass production of both invasive and native focal plants. Invasive and native focal plants were neither competitively suppressed nor facilitated by conspecific neighbors. Taken together, these results suggest that co-occurring invasive exotic plant species may facilitate each other in low-nutrient habitats but compete in high-nutrient habitats.

Changing disturbance regimes, material legacies, and stabilizing feedbacks: Dead coral skeletons impair key recovery processes following coral bleaching.

Ecosystem responses to disturbance depend on the nature of the perturbation and the ecological legacies left behind, making it critical to understand how climate-driven changes in disturbance regimes modify resilience properties of ecosystems. For coral reefs, recent increases in severe marine heat waves now co-occur with powerful storms, the historic agent of disturbance. While storms kill coral and remove their skeletons, heat waves bleach and kill corals but leave their skeletons intact. Here, we explored how the material legacy of dead coral skeletons modifies two key ecological processes that underpin coral reef resilience: the ability of herbivores to control macroalgae (spatial competitors of corals), and the replenishment of new coral colonies. Our findings, grounded by a major bleaching event at our long-term study locale, revealed that the presence of structurally complex dead skeletons reduced grazing on turf algae by ~80%. For macroalgae, browsing was reduced by >40% on less preferred (unpalatable) taxa, but only by ~10% on more preferred taxa. This enabled unpalatable macroalgae to reach ~45% cover in 2 years. By contrast, herbivores prevented macroalgae from becoming established on adjacent reefs that lacked skeletons. Manipulation of unpalatable macroalgae revealed that the cover reached after 1 year (~20%) reduced recruitment of corals by 50%. The effect of skeletons on juvenile coral growth was contingent on the timing of settlement relative to the disturbance. If corals settled directly after bleaching (before macroalgae colonized), dead skeletons enhanced colony growth by 34%, but this benefit was lost if corals colonized dead skeletons a year after the disturbance once macroalgae had proliferated. These findings underscore how a material legacy from a changing disturbance regime can alter ecosystem resilience properties by disrupting key trophic and competitive interactions that shape post-disturbance community dynamics.

Impact of aminopropyl units on physisorption in mesostructured silica is larger for CH4 than CO2 and depends on pore curvature

Mesoporous silica-based materials attract great interest for diverse applications, including capture, storage, and catalysis due to their large surface area, uniform pore size distribution, and customizable surface. The regular 2D hexagonal pore symmetry of MCM-41 makes it an ideal model. Amine groups are introduced to enhance CO2 adsorption, but the interplay of factors influencing overall performance, including pore size, remains unclear. This computational study explores the physisorption of CO2 and CH4, shedding light on the microscopic details underlying adsorption capacity and selectivity. Three aminopropyl-functionalized MCM-41 models with different pore size are compared through Grand Canonical Monte Carlo and Molecular Dynamics simulations. Aminopropyl chains affect CO2 adsorption, but its affinity for the preserved silanol groups is larger. In addition, the competitive interaction between amine and silanol groups emerged, and it is pore curvature dependent. Surprisingly, CH4 physisorption is influenced even more by surface functionalization. Results show a non-monotonic trend as a function of pore size. Local density of the alkyl chains plays the major role. Overall, the intermediate pore size demonstrates the best performance, thanks to the balance among the various effects. The study emphasizes the importance of understanding the interplay between material texture and gas interactions to optimize adsorption performance.

MInsc coordinates Par3 and NuMA condensates for assembly of the spindle orientation machinery in asymmetric cell division

As a fundamental process governing the self-renewal and differentiation of stem cells, asymmetric cell division is controlled by several conserved regulators, including the polarity protein Par3 and the microtubule-associated protein NuMA, which orchestrate the assembly and interplay of the Par3/Par6/mInsc/LGN complex at the apical cortex and the LGN/Gαi/NuMA/Dynein complex at the mitotic spindle to ensure asymmetric segregation of cell fate determinants. However, this model, which is well-supported by genetic studies, has been challenged by evidence of competitive interaction between NuMA and mInsc for LGN. Here, the solved crystal structure of the Par3/mInsc complex reveals that mInsc competes with Par6β for Par3, raising questions about how proteins assemble overlapping targets into functional macromolecular complexes. Unanticipatedly, we discover that Par3 can recruit both Par6β and mInsc by forming a dynamic condensate through phase separation. Similarly, the phase-separated NuMA condensate enables the coexistence of competitive NuMA and mInsc with LGN in the same compartment. Bridge by mInsc, Par3/Par6β and LGN/NuMA condensates coacervate, robustly enriching all five proteins both in vitro and within cells. These findings highlight the pivotal role of protein condensates in assembling multi-component signalosomes that incorporate competitive protein-protein interaction pairs, effectively overcoming stoichiometric constraints encountered in conventional protein complexes.

Dual-mode iodine sensing: Colorimetric and electrochemical detection methods using functionalized gold nanoparticles

Iodine in natural and treated waters exists mainly as iodide, iodate, and molecular iodine (I2). I2 is a highly volatile and reactive species impacting biological and chemical systems. Iodine, a vital micronutrient, is essential for human and animal growth and metabolism. It also plays a crucial role in synthesising artificial adrenaline within the metabolic processes of humans and animals. It is also widely used as an antiseptic, disinfectant, and for emergency water disinfection. Moreover, iodine deficiency can result in various diseases, especially hypothyroidism and goitre. Given its critical functions, it is imperative to have a straightforward, dependable, and efficient method for monitoring iodine levels. This study introduces a simple and innovative I2 detection system based on its reactivity, toxicity, and role as an indicator of oxidative conditions in water. It operates in terms of based on optical and electrochemical signal changes, utilising the anti-aggregation mechanism of gold nanoparticles (AuNPs) and 6-mercaptohexanol (MHA) for sensitive and selective detection under mild conditions. I2 determination is achieved by observing the colour change in AuNPs, which is influenced by competitive interactions between MHA, I2, and AuNPs. The optical detection system, with its low detection limit (LOD=260 nM), is based on the straightforward observation of colour changes. On the other hand, the electrochemical detection method utilises changing redox peaks observed in anodic region, providing selective and sensitive I2 detection (LOD=100 nM). The probe effectively detects the presence of I2 in real water samples as a practical application. Moreover, the proposed method revolutionises I2 detection by incorporating a smartphone for signal reading, eliminating the need for specialised equipment and significantly reducing the detection cost. This cost-effective approach carries the potential to expedite on-site and naked-eye I2 detection, opening up new possibilities for research and application.

Platform integration in ride-sourcing markets with heterogeneous passengers

This paper explores the impacts of a novel business model termed platform integration, which enables passengers to simultaneously request on-demand rides from multiple ride-sourcing platforms via a third-party integrator. In particular, we employ an equilibrium model where passenger demand and driver supply are endogenously dependent on the prices and wages that emerge from the competitive interaction between two platforms, with and without an integrator. A Hotelling model is adopted to characterize passengers’ heterogeneity in service preference for different platforms. We employ the concepts of a Nash equilibrium and a shared monopoly to analyze equilibrium outcomes that can arise in various settings of demand and supply characteristics with and without platform integration. We find that how the platform should adjust its price and wage at Nash equilibrium as potential demand increases is affected by the nature of supply. We also find that the profit at Nash equilibrium can increase or decrease in supply capacity depending on the competitive situation of the platforms. We build on these equilibrium results to analyze how platform integration affects the platform’s decision-making of price and wage, and market performance. We find that platform integration can increase platform profit but reduce driver income, and may hurt passengers who have a strong preference for one certain platform, especially in the case of a less heterogeneous supply.