Complex Formation Research Articles

Visible-Light Driven Synthesis of Vinyl Amines without Photocatalyst.

We developed a visible-light-induced vinyl amination of activated alkenes using TMSN3 and CsF through EDA complex formation under an oxygen atmosphere. Without light, the EDA complex forms between activated alkene, CsF, and oxygen. Upon exposure to light, oxygen in the complex gets excited, initiating the HAT process. This method efficiently synthesizes vinyl-amine derivatives via a radical pathway, demonstrating good functional group tolerance and high yields in a short time. Further, the late-stage functionalization enables the synthesis of biologically active heterocycles.

Prospects of phycoerythrin: Structural features, antioxidation and applications in food

Phycoerythrin (PE) is a naturally occurring plant protein of algal origin. The colour, bioactivity and stability of PE are inextricably linked to its structure. PE has powerful antioxidant properties that effectively prevent oxidative stress and cellular damage, for which the chromophore structure plays a key role. However, the relationship between the chromophore and thermal stability is unclear in PE. The environmental factors affecting the thermal stability of PE are mainly light, high temperature and extreme pH. PE stability can be enhanced through various techniques, including the incorporation of additives, cross-linking processes, and the formation of complexes. Improving the stability of PE is of significant importance for its applications within the food industry. This paper outlines the structural characteristics of PE, discusses the relationship between its structure and antioxidant activity, and focuses on the application of PE in the food industry, as well as the factors affecting its stability and strategies for its improvement.

Sorption-spectrophotometric determination of bismuth ion (III) using immobilised xylenol orange on modified polyacrylonitrile

ABSTRACT This study presents a new sorption-spectrophotometric method for determining bismuth (III) ions using a new adsorbent for PPM-1 fibre immobilised with xylenol orange. The complex exhibited a maximum reflectance at 550 nm and absorption at 530 nm, indicating stable formation. The method demonstrated high sensitivity with a detection limit of 0.1 µg/mL and high selectivity, minimising interference from other metal ions. Optimal pH for complex formation was 1.37, with faster response and higher sensitivity in the immobilised state (detection limit 0.12 µg/mL, formation time 10 minutes). The complex adhered to the Bouguer-Lambert-Beer law within 3–42 µg/25 mL. Interferences from Cu2+, Ag+, Pd2+, and Fe3+ were reduced when the reagent was immobilised. Conductometric analysis confirmed the stable formation of the complex. Validation using model mixtures and pharmaceutical preparations showed accurate bismuth determination with an error margin of 0.005. For example, a mixture containing 25 µg of bismuth with zinc and cadmium yielded 25.20 µg, and De-nol had a found content of 49.50 µg for 50.00 µg added. IR spectroscopy confirmed complex formation with significant shifts in absorption bands. SEM and EDS analysis validated the reagent’s effective immobilisation and interaction with bismuth ions. The method provides a rapid, accurate, and environmentally friendly approach for bismuth analysis, demonstrating high reproducibility, sensitivity, and selectivity, suitable for environmental monitoring and pharmaceutical quality control.

Structural features of carrot α-tubulin predetermining the natural resistance to dinitroaniline herbicides

Aim. To explain the natural resistance of Daucus carota L. to dinitroaniline herbicides. To clarify features of the carrot α-tubulin that may affect formation of the ligand-protein complex based on the structural and electrostatic analysis of the ligand-binding site. Methods. Reconstruction of the spatial structure of α-tubulin from D. carota and Toxoplasma gondii using profile (Swiss-Model) and de-novo (AlphaFold2) modeling. Molecular dynamics (MD) simulations of the built 3D-models in Gromacs. Analysis of the molecular electrostatics with PDB2PQR/APBS tools. Visualization and analysis of molecular structures in PyMOL. Results. It has been shown that along with the typical positive charge of the dinitroaniline-binding pocket, all isotypes of carrot α-tubulin demonstrate negatively charged regions that may cause conflicts with the nitro-groups of the ligands. Also, the MD-stable negatively charged "bridge" between Cys316 and the aryl-fragment of Phe255 was observed in all α-tubulin isotypes. In our opinion, it not only competes with the cyclic fragment of dinitroanilines, but overall prevent the opening of the site pocket in carrot α-tubulin. Conclusions. It was clarified that natural resistance of D. carota to dinitroaniline herbicides may be associated with steric and electrostatic conflicts observed in in all α-tubulin isotypes. In our opinion, it prevents interaction with dinitroaniline compounds at the stage of primary site recognition on the early stages of protein-ligand complex formation.

The Milling Method in Formation of Inclusion Complex p-Methoxycinnamic Acid-Hydroxypropyl-β-Cyclodextrin.

p-methoxycinnamic acid (pMCA) is a substance with several pharmacological activities, derived from the rhizome of Kaempferia galanga Linn. The solubility of pMCA can be increased by the formation of inclusion complexes (IC) using hydroxypropyl-βcyclodextrin (HPβCD) compounds. IC are obtained through the milling method, which is a simple, environmentally friendly, and low-cost manufacturing method. The process involves the pounding of material with a certain speed and impact force. This research aims to characterize the pMCA-HPβCD IC made using the milling method. Milling the mixture of pMCA and HPβCD using a ball mill is a common technique to enhance the formation of the inclusion complex. The IC’s physical characteristics were analyzed in terms of their morphology, particle size, crystallinity, and thermal properties. The dissolution profile was also performed using paddle-typed dissolution apparatus (Type II) with 500 mL distilled water as dissolution medium. The amount of pMCA dissolved was determined using UV spectrophotometry. The dissolution parameter was determined as dissolution efficiency at 60 minutes (DE60). The IC particles were irregular in shapes and porous. The size was reduced as compared to the individual components. The XRD revealed that the ICs were amorphous. The DE60 of IC increased by a factor of 4.3 compared to the pure pMCA. In conclusion, the milling method successfully formed complex of pMCA-HPβCD with different characteristics from the initial compound and was significantly increased the percentage of the dissolved pMCA.

Phylogenomic instructed target analysis reveals ELAV complex binding to multiple optimally spaced U-rich motifs.

ELAV/Hu RNA-binding proteins are gene-specific regulators of alternative pre-mRNA processing. ELAV/Hu family proteins bind to short AU-rich motifs which are abundant in pre-mRNA, making it unclear how they achieve gene specificity. ELAV/Hu proteins multimerize, but how multimerization contributes to decode degenerate sequence environments remains uncertain. Here, we show that ELAV forms a saturable complex on extended RNA. Through phylogenomic instructed target analysis we identify the core binding motif U5N2U3, which is repeated in an extended binding site. Optimally spaced short U5N2U3 binding motifs are key for high-affinity binding in this minimal binding element. Binding strength correlates with ELAV-regulated alternative poly(A) site choice, which is physiologically relevant through regulation of the major ELAV target ewg in determining synapse numbers. We further identify a stem-loop secondary structure in the ewg binding site unwound upon ELAV binding at three distal U motifs. Base-pairing of U motifs prevents ELAV binding, but N6-methyladenosine (m6A) has little effect. Further, stem-loops are enriched in ELAV-regulated poly(A) sites. Additionally, ELAV can nucleate preferentially from 3' to 5'. Hence, we identify a decisive mechanism for ELAV complex formation, addressing a fundamental gap in understanding how ELAV/Hu family proteins decode degenerate sequence spaces for gene-specific mRNA processing.

Simulating multi-scale optimization and variable selection in species distribution modeling

Species distribution modeling (SDM) is a fundamental tool in theoretical and applied ecology. However, relatively little is known about the performance of different approaches for scale optimization, model selection, and algorithmic prediction in the context of nonlinear, multiscale and interactive relationships between environmental variables and species occurrence. Modelers often struggle to optimize a tradeoff between ecological relevance, model robustness, complexity, and overfitting. In this paper, we investigated several methods designed to optimize spatial scale and variable selection in SDMs, in each case evaluating model fitness, parsimony and predictive performance. We used a simulation approach to produce a large pool of alternative underlying habitat relationships that reflect a broad range of realistic habitat associations. We also compared several different modeling algorithms, including logistic regression with a generalized linear model (GLM), Lasso and Elastic-Net Regularized GLMs (GLMNet), and random forest (RF), as well as alternative variable and scale selection methods. We found that GLM methods employing all-subsets dredge routines for variable selection were consistently the best predictors based on all criteria of our model performance assessment and across all attributes of the simulated underlying relationship, including nonlinearity and interaction. We had expected machine learning approaches, such as random forest, to perform better in these more complex forms of species-environment relationships. GLM using dredge variable selection was also the method that included the fewest spurious covariates and included the most correct predictors as a proportion of all predictors. We found that univariate scaling was the most robust method of variable and scale selection, along with Minimal Redundancy Maximal Relevancy (MRMR) which performed equivalently. The simulation experiment presented here provides a robust assessment of simulated multi-species distribution model performance, complexity and fidelity. By simulating a large range of potential habitat relationships with varying spatial scale, effect sizes, linearity, and interactions, we comprehensively evaluated model performance across gradients of complexity of the underlying relationships and violations of classical statistical assumptions. This study provides a valuable assessment and a broader example of the power and utility of controlled simulation experiments in habitat relationships and other ecological spatial predictive modeling.

Lactoferrin-Based Heteroprotein Systems, From Their Formation Mechanism, Properties, To Applications.

Lactoferrin (LF) is an important iron-binding glycoprotein found in milk and mucosal secretions. The alkaline lactoferrin can interact with some acidic proteins to form heteroprotein systems with multifunctional properties and a wide range of applications. Lactoferrin can interact with animal and plant proteins mainly through the electrostatic forces, dipolar attraction, and hydrophobic interactions. In this review, the types of heteroprotein complexes formed by the complex coacervation of lactoferrin with other proteins are introduced, including the preparation, structure, and applications. The factors affecting the formation of heteroprotein complexes are described, such as pH, ionic strength, mixing ratio, total protein concentration, and temperature. The issues and challenges in the formation of heteroprotein complexes are also discussed.

Possible roles of heteroreceptor complexes in excitotoxic processes

Excitotoxicity represents a neuropathological process, describing the toxic actions of excitatory neurotransmitters, where the excessive or prolonged activation of glutamate receptors triggers a cascade of events leading to neuronal injury or death. Under conditions of reduced energy availability and increased oxidative stress neurons become particularly vulnerable to excitotoxicity and a large body of available evidence indicates that excitotoxicity represents a central mechanism in the pathogenesis of acute and degenerative diseases of the central nervous system. Astrocytes represent key elements in the regulation of glutamate homeostasis by their opposing functions of glutamate uptake and release, and microglial cells play an important role in the response to damage. Depending on the phenotype they assume when activated, microglial cells can trigger immune defense or neuroprotective processes. To perform their functions both glial cell populations monitor the extracellular space through a panel of receptors. Furthermore, a variety of signaling pathways also contribute to the modulation of the glutamatergic transmission, acting on specific cell receptors expressed by neurons, astrocytes, and microglia. In the last decades, evidence has been provided that receptors of almost all families can establish structural receptor-receptor interactions, leading to the formation of heteroreceptor complexes at the cell membrane of neurons and glial cells. The cooperativity that emerges in the actions of ligands of the monomers forming these assemblies provides the cell decoding apparatus with flexible dynamics in terms of recognition and signal transduction and allows an integration of the incoming signals already at the membrane level. Available data on possible modulatory roles played by heteroreceptor complexes in excitotoxic processes will be here reviewed and discussed. From the pharmacological standpoint, these findings may offer possibilities to explore novel therapeutic strategies targeting receptor complexes to address disorders of the central nervous system associated with dysregulation of glutamatergic signaling.

Drug Binding to Partially Unfolded Serum Albumin: Insights into Nonsteroidal Anti-Inflammatory Drug Naproxen-BSA Interactions from Spectroscopic and MD Simulation Studies.

Understanding the binding details of a small-molecule drug to a protein in its partially unfolded state is important for drug delivery as it provides insight into the overall drug-binding ability of the protein, even when the majority of binding pockets in its unfolded state are impaired. The interaction of partially unfolded proteins with drugs remains poorly understood due to a lack of structural information on proteins in their partially unfolded states. Here, we studied the interaction between serum albumin (bovine serum albumin (BSA) as a model system), an abundant protein in blood serum that is an effective carrier for numerous known drugs, and a nonsteroidal anti-inflammatory drug (NSAID) naproxen (NPS) using various spectroscopic and computational methods. Molecular dynamics simulations starting from the drug-unbound state and performed at physiological and higher temperatures revealed novel hydrophobic sites on the BSA surface. We analyzed the BSA-NPS interaction in the presence and absence of the cationic organized assembly CTAB and two oligosaccharides (β-CD and 2-HP-β-CD) at different excitation wavelengths. The solvation dynamics of BSA under NPS-bound conditions became ∼4.6% faster. Oligosaccharides were found to increase the solubility of NPS by providing a hydrophobic environment for the formation of inclusion complexes through host-guest interactions. These findings provide a comprehensive overview and uncover the binding model and mechanism of interaction of NPS with BSA, revealing hydrophobic and electrostatic interactions and hydrogen bonds required for BSA to bind NPS at these noncanonical sites. The molecular-level understanding of the binding mechanism of commonly used NSAIDs like NPS with partially unfolded BSA will be useful in designing pharmaceutically important molecules with efficient loading and delivery properties.

‘It’s a tiger instinct – that’s my baby!’: affective practices of care in parents’ educational activism

This article presents findings from a qualitative study exploring parents’ struggles over their children’s education. Drawing on affective practice theory (Wetherell 2012) and feminist care ethics (Fisher and Tronto 1990), we offer insights into the affective practices of care driving parents’ educational activism. We detail how parents’ activism is rooted in both powerful feelings of parental responsibility and wider, more altruistic concerns. We argue that parents’ activism disrupts the binary between altruism and self-interest, indicating instead they can be mutually constitutive of collective action; a complex form of affective practice we designate altruistic self-interest. Our analysis suggests parental activism can be a force for progressive educational change in which care for intimates and care for others coincide, but also that educational authorities might adopt a more care-full approach when making key decisions affecting children, families and communities.

The Impact of Varying Lactose-to-Maltodextrin Ratios on the Physicochemical and Structural Characteristics of Pasteurized and Concentrated Skim and Whole Milk-Tea Blends.

This study investigates the impact of substituting lactose with maltodextrin in milk-tea formulations to enhance their physicochemical and structural properties. Various lactose-to-maltodextrin ratios (100:0, 90:10, 85:15, 80:20, 75:25) were evaluated in both post-pasteurized and concentrated skim milk-tea (SM-T) and whole milk-tea (WM-T) formulations. Concentration significantly improved the zeta potential, pH, and browning index in both SM-T and WM-T compared to pasteurization. L:M ratios of 90:10 and 75:25 in WM-T and 90:10 and 80:20 in SM-T showed higher phenolic preservation after concentration due to structural changes resulting from the addition of maltodextrin and water removal during prolonged heating. The preservation effect of phenolic components in both WM-T and SM-T is governed by many mechanisms including pH stabilization, zeta potential modulation, protein interactions, complex formation, and encapsulation effects. Therefore, optimizing milk-tea stability and phenolic preservation through L:M ratio adjustments provides a promising approach for enhancing milk-tea properties.

Effect of structural evolution and orientation behavior on optical properties of iodine-dyed PVA film during uniaxial stretching

In the process of preparing polarizing film, based on the research on the influence of the initial condensed structure of Poly (vinyl alcohol) (PVA) film on the dyeing and stretching process, the connection between the structure and performance of polarizing film is established, which is more conducive to understanding the post-processing process of solution casting molding of optical grade PVA film and the optimization of subsequent dyeing and stretching process. In this paper, PVA film with an appropriate swelling degree were selected for dyeing treatment, and the evolution of the condensed structure during stretching was studied in detail. The work also examined the formation and orientation of PVA-iodine complexes and the feedback effect of complex formation on the structural evolution of the film, with the goal of establishing the relationship between stretching ratio, structure, and performance of the polarizing film. The results show that the dyeing process inhibits the recrystallization of the PVA film during uniaxial stretching. However, the PVA-iodine complexes formed act as "anchors" to stabilize the oriented microfiber network, reducing the critical strains (εw and εs) required for the PVA film to enter the strain-hardening zone. Furthermore, as strain increases, the content of polyiodide ions and PVA-iodine complexes in the dyed PVA film also increases, especially making the formation of long iodide chains (I5−) and PVA-I5− complex more sensitive. Additionally, with increasing strain, both the transmittance and degree of polarization of the dyed PVA film improve, reaching optimal values in the strong strain-hardening zone (>εs). This indicates that εs is the minimum critical strain required to ensure optimal polarization performance of the film in the visible light region.

Chitosan-Polyaniline (Bio)Polymer Hybrids by Two Pathways: A Tale of Two Biocomposites.

Previous research highlights the potential of polyaniline-based biocomposites as unique adsorbents for humidity sensors. This study examines several preparative routes for creating polyaniline (PANI) and chitosan (CHT) composites: Type 1-in situ polymerization of aniline with CHT; Type 2-molecular association in acidic aqueous media; and a control, Type 3-physical mixing of PANI and CHT powders (without solvent). The study aims to differentiate the bonding nature (covalent vs. noncovalent) within these composites, which posits that noncovalent composites should exhibit similar physicochemical properties regardless of the preparative route. The results indicate that Type 1 composites display features consistent with covalent and hydrogen bonding, which result in reduced water swelling versus Type 2 and 3 composites. These findings align with spectral and thermogravimetric data, suggesting more compact structure for Type 1 materials. Dye adsorption studies corroborate the unique properties for Type 1 composites, and 1H NMR results confirm the role of covalent bonding for the in situ polymerized samples. The structural stability adopts the following trend: Type 1 (covalent and noncovalent) > Type 2 (possible trace covalent and mainly noncovalent) > Type 3 (noncovalent). Types 2 and 3 are anticipated to differ based on solvent-driven complex formation. This study provides greater understanding of structure-function relationships in PANI-biopolymer composites and highlights the role of CHT as a template that involves variable (non)covalent contributions with PANI, according to the mode of preparation. The formation of composites with tailored bonding modalities will contribute to the design of improved adsorbent materials for environmental remediation to versatile humidity sensor systems.

Exploring the effects of 4-chloro-o-phenylenediamine on human fibrinogen: A comprehensive investigation via biochemical, biophysical and computational approaches

Fibrinogen (Fg), an essential plasma glycoprotein involved in the coagulation cascade, undergoes structural alterations upon exposure to various chemicals, impacting its functionality and contributing to pathological conditions. This research article explored the effects of 4-Chloro-o-phenylenediamine (4-Cl-o-PD), a common hair dye component (IUPAC = 1-Chloro-3,4-diaminobenzene), on human fibrinogen through comprehensive computational, biophysical, and biochemical approaches. The formation of a stable ligand-protein complex is confirmed through molecular docking and molecular dynamics simulations, revealing possible interaction having a favorable −4.8 kcal/mol binding energy. Biophysical results, including UV–vis and fluorescence spectroscopies, corroborated with the computational findings, whereas Fourier transform infrared spectroscopy (FT-IR) and circular dichroism spectroscopy (CD) provide insights into the alterations of secondary structures upon interaction with 4-Cl-o-PD. Anilinonaphthalene-sulfonic acid (ANS) fluorescence showed a partially unfolded protein, with enhanced α to β-sheet transition as evidenced by thioflavin T (ThT) spectroscopy and microscopy. Moreover, biochemical assays confirmed the formation of carbonyl compounds that may be responsible for the oxidation of methionine residues in fibrinogen. Electrophoresis and electron microscopy confirmed the formation of aggregates. Our findings elucidate the interaction pattern of 4-Cl-o-PD with Fg, leading to structural perturbation, which may have potential implications for fibrinogen misfolding or its aggregation. Protein aggregation or its misfolded products affect peripheral tissues and the central nervous system. Many chronic progressive diseases, like type II diabetes mellitus, Alzheimer's disease, Parkison's disease, and Creutzfeldt-Jakob disease are associated with intrinsically aberrant disordered proteins. Understanding these interactions may offer new perspectives on the safety and biocompatibility of dye compounds, which may contribute to developing improved strategies for acquired amyloidogenesis.

Data-driven robust optimization in the face of large-scale datasets: An incremental learning approach

One of the most significant current discussions in optimization under deep uncertainty is integrating machine learning and data science into robust optimization, which has led to the emergence of a new field called Data-Driven Robust Optimization (DDRO). When creating data-driven uncertainty sets, it considers a dataset’s complexity, hidden information, and inherent form. One of the more practical machine learning algorithms for creating data-driven uncertainty sets is support vector clustering (SVC). This algorithm has no prerequisites for preliminary information to generate uncertainty sets with arbitrary geometry. More scenarios can reduce risk when developing SVC-based uncertainty sets. However, the lack of a systematic way to manage the large number of these scenarios hinders the employment of SVC. This paper puts forward an incremental learning algorithm based on support vector clustering, called Incremental Support Vector Clustering (ISVC), to construct an uncertainty set incrementally and efficiently using large datasets. This approach’s novelty and main contributions include incrementally constructing uncertainty sets and dynamic management of outliers. In order to update the temporarily stored Bounded Support Vectors (BSV) and identify outliers, the idea of BSV-archive is offered, where the revision-and-recycle operation is tailored to do just that. As a result, some of the newly acquired information is preserved. Experiments on large-scale datasets demonstrate that the proposed ISVC approach can create an uncertainty set comparable to that of an SVC-based method while using significantly less time.

Synthesis and reactivity of isomeric Ru complexes with hydroxypyridyl fragment: Active catalysts for β‑alkylation of secondary alcohols with primary alcohols

When the ligand LOH, containing a 2-hydroxy pyridine group, reacts with an equimolar amount of the precursor Ru(DMSO)4Cl2, two isomeric ruthenium complexes are formed. These isomers are termed cis-1 and trans-1, based on the relative positions of the N atom in N-(2-(6-hydroxy pyridin-2-yl)phenyl)acetamide and the pyridine groups of bis((1,4-pyridin-2-yl)methyl)amine. Treatment of these isomers with equimolar amounts of NaH results in deprotonation of the uncoordinated hydroxy pyridine groups, leading to the formation of complex 2 with newly coordinated pyridine groups. The catalytic activity of these three ruthenium complexes in the β-alkylation reaction of primary alcohols and secondary alcohols was evaluated, with complex 2 displaying the highest activity and selectivity. Complex 2 may be seen as an intermediate in the catalysis of the β-alkylation reaction by the isomers (cis-1 and trans-1). These findings are valuable for the development of more effective bifunctional catalysts.

Iron chelating, antioxidant, and anti-inflammatory properties of brazilin from Caesalpinia sappan Linn

BackgroundIron overload and inflammation are severe conditions that can lead to various chronic diseases. However, the current iron chelator drugs have their limitations. The phytochemical compounds from herbals, such as brazilin, the major active compound in Caesalpinia sappan Linn., have significant therapeutic potential in various chronic diseases. Our study was designed to examine the effect of brazilin on iron chelating properties, antioxidant activity in hepatocytes, and anti-inflammatory potential in macrophages. MethodsThis study focused on the isolation, purification, and evaluation of brazilin, the principal bioactive constituent found in C. sappan wood. Brazilin was extracted via methanol maceration followed by column chromatography purification. The purified compound was characterized using high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry (MS). The antioxidant potential of brazilin was assessed by in vitro assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzthiazolin-6-sulfonic acid (ABTS), and ferric-reducing antioxidant power (FRAP). Furthermore, its cellular antioxidant activity was evaluated using hydrogen peroxide-induced oxidative stress in the hepatocellular carcinoma cell line (Huh-7). The iron-chelating capacity of brazilin was determined spectrophotometrically, and Job's plot method was used to elucidated the stoichiometry of the iron-brazilin complex formation. The anti-inflammatory properties of brazilin were investigated in lipopolysaccharide (LPS)-stimulated macrophages (RAW 264.7). Nitric oxide (NO) inhibition was quantified using the Griess reagent, while the expression levels of pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), were evaluated by RT-qPCR. ResultsThe results demonstrated that brazilin exhibited potent antioxidant activity in vitro and hepatocytes in a concentration-dependent manner. It also showed anti-inflammatory activity, in which NO production was significantly reduced and IL-6 and TNF-α expression in LPS-induced macrophages were repressed. Furthermore, it can bind ferric and ferrous ions. Brazilin acts as a bidentate iron chelator that forms a complex with iron in a 2:1 ratio, and two water molecules are used as additional chelators in this complex. ConclusionsOur findings have significant implications. Brazilin can potentially alleviate the harmful effects of iron-induced oxidative stress and inflammatory disorders.

Technological hedging and differentiated responses of Southeast Asian countries to U.S.–China technological competition: a case study on artificial intelligence (AI)

The rise of artificial intelligence (AI), represented by ChatGPT, has triggered a new wave of technological competition between nations. Major powers like China and the United States, backed by abundant resources, dominate the discourse and hold a significant advantage in the AI field. However, as the technological rivalry between these two countries intensifies, AI represents a classic ‘double-edged sword’ for many small and medium-sized countries. Therefore, the core argument of this paper is that the AI policies of small and medium-sized countries are not simply about bandwagoning or depending on major powers. At their core, these policies represent a complex form of technological hedging. External security concerns drive small and medium-sized countries to adopt hedging as a primary strategy, while internal interest preferences influence the varying intensities of this technological hedging. The findings of this paper indicate that small countries’ technological policies can be categorized into three models: strong hedging, medium hedging, and weak hedging. Different paths of technological hedging reflect the rational balance these nations make between security and economic interests in different contexts. The case of AI development in ASEAN also demonstrates the significant imbalance between member states. Singapore is classified as a technological frontrunner, while Malaysia, Indonesia, and Vietnam are categorized as followers. Laos, Cambodia, Myanmar, Thailand, Brunei, and the Philippines are considered latecomers in the field of AI. In terms of specific AI policies, Singapore and Vietnam adopt a strong technological hedging strategy, seeking more cooperation and interaction with the U.S. or other countries due to caution and concerns about China’s technological security. Malaysia, Indonesia, Thailand, and the Philippines follow a medium hedging strategy, while Cambodia, Laos, Myanmar, and Brunei adopt a weak hedging approach. The differences in hedging intensity are primarily due to varying internal legitimacy pathways and the strength of backup resources. ASEAN member states pursue different technological paths based on their own circumstances to promote AI development.

Complex Formation of Gold Nanoparticles with Collagen in Aqueous Media Studied by X-ray Scattering and Absorption Spectroscopy.

Small-angle X-ray scattering and UV-vis absorption measurements were performed on mixed solutions of gold nanoparticles (AuNPs) and atelocollagen (AC), triple-helical collagen without telopeptide, in acetate buffer at pH 4 under different temperature conditions, i.e., preparation temperature Tprep and measurement temperature Tmeas. Due to the significantly higher electron density of gold than that of AC, the structure factor S(q) of AuNPs is readily estimated from the scattering intensities of AuNP-only and mixed solutions. The resulting S(q) profile for the mixed solution indicated significant attractive interactions, especially for the smaller AuNPs. Therefore, the sticky sphere model was applied to analyze S(q) to determine the interaction parameters at different Tprep and Tmeas. The attractive interactions between AuNPs were higher at higher Tprep, suggesting that single-chain AC tends to make the interactions between AuNPs more attractive than those for triple-helical AC. Complex formation was also detected by the aggregation-induced surface plasmon absorption shift. More densely packed AuNPs were detected from the absorption spectra for higher AuNP content at which the ζ potential disappeared, while a split absorption band was also found, indicating that not all AuNPs can form a complex with AC at ζ = 0.