Pair Formation Research Articles

Unravelling the mating system in the pea crab Austinixa leptodactyla (Coelho, 1997) (Decapoda: Brachyura: Pinnotheridae)

ABSTRACT Brachyuran crabs of the family Pinnotheridae have a phylogenetic history linked to a symbiotic lifestyle. Here, we examined the host-use pattern (ie social organisation), sex ratio, sexual dimorphism and relative growth of the crab Austinixa leptodactyla, a symbiont of the ghost shrimp Neocallichirus maryae. We use these analyses to investigate the A. leptodactyla mating system on the basis that monogamous species occupy host burrows as male–female pairs and have a low degree of sexual dimorphism. To this end, a total of 129 individuals (62 males and 67 females, including 29 brooding females) were retrieved within the burrows of their respective hosts in a population from north-eastern Brazil. Our results show that A. leptodactyla inhabited the host burrows either solitarily (61%) or in pairs (39%). Most of the solitary females (88%) were ovigerous, while the pairs were mainly composed of one male and one female crab, with 13 (65%) of these heterosexual couples including one ovigerous female. Body size of paired crabs of the opposite sex was poorly correlated. The finding of solitary females incubating embryos and the lack of correlation between body size of heterosexual pairs suggest that pair formation is not long term. The sex ratio did not differ significantly from the evenness and no sexual dimorphism was detected between body size or cheliped size of males and females. Body colouration of males was more similar to the sand grains of the beach than that of females. This suggests that males are better adapted than females to roam on the surface of the beach in search of burrows occupied by receptive sexual partners. The observations further support the suggestion that A. leptodactyla is polygamous, but behavioural and histological studies are needed to reveal the details of the polygamous mating system herein inferred for A. leptodactyla.

Detection of thymine stretches in DNA oligonucleotides at the surface of hanging mercury drop electrode using thymine-mercury base pair formation

Detection of thymine stretches in DNA oligonucleotides at the surface of hanging mercury drop electrode using thymine-mercury base pair formation

Ru(II)-Based Multitopic Hosts for Fullerene Binding: Impact of the Anion in the Recognition Process.

The development of multitopic hosts for fullerene recognition based on nonplanar corannulene (C20H10) structures presents challenges, primarily due to the requirement for synergistic interactions with multiple units of this polycyclic aromatic hydrocarbon. Moreover, increasing the number of corannulene groups in a single chemical structure while avoiding the cost of increasing flexibility has been scarcely explored. Herein, we report the synthesis of a family of multitopic Ru(II)-polypyridyl complexes bearing up to six units of corannulene arranged by pairs, offering a total of three molecular tweezers. All of them are fixed by the central atom and organized in an octahedral structure. Their fullerene recognition capabilities have been thoroughly demonstrated toward C60 and C70 showing that they can reasonably accommodate up to three fullerenes per host in a noncooperative manner. There are, however, some features that diverge from comparable hosts in the literature, such as the low value of several association constants. This behavior, supported by theoretical studies, is attributed to the presence of two noninnocent BAr4F anions that interfere with the supramolecular binding through ion pair formation. These findings highlight the crucial role of selecting compatible ionic species in supramolecular host design as they can significantly influence the recognition process.

Half-line kink scattering in the ϕ4 model with Dirichlet boundary conditions

In this work, we investigate the dynamics of a scalar field in the nonintegrable ϕ4 model, restricted to the half-line. Here we consider singular solutions that interpolate the Dirichlet boundary condition ϕ(x = 0, t) = H and their scattering with the regular kink solution. The simulations reveal a rich variety of phenomena in the field dynamics, such as the formation of a kink-antikink pair, the generation of oscillons by the boundary perturbations, and the interaction between these objects and the boundary, which causes the emergence of boundary-induced resonant scatterings (for example, oscillon-boundary bound states and kink generation by oscillon-boundary collision) founded into complex fractal structures. Linear perturbation analysis was applied to interpret some aspects of the scattering process. We detected the presence of two shape modes near the boundary. The power spectral density of the scalar field at a fixed point leads to several frequency peaks. Most of them can be explained with some interesting insights for the interaction between the scattering products and the boundary.

Highly Nucleophilic Pyridinamide Anions in Apolar Organic Solvents due to Asymmetric Ion Pair Association.

Free ions in organic solvents of low polarity would be valuable tools for the activation of low-reactivity substrates. However, the formation of unreactive ion pairs at concentrations relevant for synthesis has prevented the success of this concept so far. On the example of highly nucleophilic pyridinamide phosphonium salts in dichloromethane, we show that asymmetric aggregation offers a solution to this general problem. A combination of conductivity, diffusion-ordered NMR (DOSY), and kinetic measurements utilizing a refined ionic strength-controlled benzhydrylium ion methodology enables unique insight into the aggregation/association state of the ions and the nucleophilicity of the involved anions. This approach reveals that pyridinamide tetraphenylphosphonium salts aggregate in dichloromethane solution asymmetrically to form sandwich-type cations and anions together with their free counterions. The nucleophilicity of free pyridinamide ions exceeds that of the neutral reference nucleophile 9-azajulolidine (TCAP) by up to 2 orders of magnitude. Based on these results, we suggest that asymmetric aggregation in organic solvents of low polarity might be a general pathway to boost the reactivity of anionic nucleophiles.

Luminescent Cu nanoclusters-encapsulated ZIF-8 as on-off-on fluorescent probe for efficient and selective quantification of E. coli.

Rapid and accurate detection of Escherichia coli (E. coli) is critical for maintaining water quality, and protecting aquatic ecosystems and public health. This research focuses on the development of a Förster resonance energy transfer (FRET)-based "turn-on" fluorescent nanosensor for real time, sensitive detection of E. coli. Copper nanoclusters-encapsulated metal organic frameworks (CuNCs@ZIF-8) were sythesizedas a fluorescent donor with excellent luminescence properties. Further, MnO2 nanospheres were synthesized as a receptor with good adsorption and quenching abilities. This novel nanoconjugate (CuNCs@ZIF-8@ MnO2) was employed for the construction of a sensitive, accurate, and rapid sensing platform against E. coli in water on the basis of p-benzoquinone/hydroquinone (p-BQ/HQ) redox pair formation. Fluorescence is quenched by energy transfer when MnO2 nanospheres are added to CuNCs@ZIF-8. Upon contact with E. coli, NADH-quinone reductase converts p-BQ to HQ, which reduces MnO2 to Mn2+, releasing the nanospheres and restoring fluorescence in the composite. Based on this FRET ON-OFF-ON fluorescent probe, E. coli can be detected across a broad concentration range (5 × 101 to 5 × 105CFU/mL), with a detection limit as low as 8CFU/mL within 50min. The sensor's practicality was verified through the investigation of E. coli in real water samples, with recoveries in the range 94.3 to 106.5%. This approach offers an efficient method for on-site detection and quantification of E. coli in both environment and food safety domains.

Formation of Lewis acid-base pairs between carboxyl grafted ZnxCd1-xS and imine COF enhance hydrogen production under visible light

Formation of Lewis acid-base pairs between carboxyl grafted ZnxCd1-xS and imine COF enhance hydrogen production under visible light

Non-ionic surfactant self-assembly in calcium nitrate tetrahydrate and related salts.

Self-assembly of amphiphilic molecules can take place in extremely concentrated salt solutions, such as inorganic molten salt hydrates or hydrous melts. The intermolecular interactions governing the organization of amphiphilic molecules under such extreme conditions are not yet fully understood. In this study, we investigated the specific effects of ions on the self-assembly of the non-ionic surfactant C12H25(OCH2CH2)10OH (C12E10) under extreme salt concentrations, using calcium nitrate tetrahydrate as a reference. The mixtures of Ca(NO3)2·4H2O and C12E10 displayed lyotropic (H1 and I1) and micellar phases, in contrast to CaCl2·xH2O-C12E10 or CaBr2·xH2O-C12E10 mixtures where mesostructurally ordered salt-surfactant complexes were observed. The Ca(NO3)2·4H2O-C12E10 system was thoroughly investigated by constructing its binary phase diagram and performing thermal and spectral comparisons with other salt hydrates. The Ca(NO3)2 system displayed significantly higher isotropization temperatures than zinc, aluminium, and lithium nitrate systems. ATR-FTIR analysis revealed that Ca2+ primarily interacts with the surfactant head groups through ion-dipole interactions, while these interactions were less pronounced with other cations. The results show that an intermediate hydration/coordination energy of the metal ion can lead to stronger metal-surfactant interactions and thermally more stable liquid crystals. Comparison between the Ca(NO3)2, CaCl2, and CaBr2 systems suggests that reduced ion pair formation enhances the interactions between Ca2+ and oxyethylene groups, leading to the salting-out of salt-surfactant complexes. Despite its low water content and strong intermolecular interactions, the Ca(NO3)2·xH2O-C12E10 system exhibited an electrical conductivity of up to 1.0 × 10-3 S cm-1 with 4 water molecules per salt, making it a promising medium for electrochemical applications.

Cryo-EM structure of the conjugation H-pilus reveals the cyclic nature of the TrhA pilin.

Conjugation, the major driver of the spread of antimicrobial resistance genes, relies on a conjugation pilus for DNA transfer. Conjugative pili, such as the F-pilus, are dynamic tubular structures, composed of a polymerized pilin, that mediate the initial donor-recipient interactions, a process known as mating pair formation (MPF). IncH are low-copy-number plasmids, traditionally considered broad host range, which are found in bacteria infecting both humans and animals. The reference IncHI1 plasmid R27, isolated from Salmonella enterica serovar Typhi, encodes the conjugative H-pilus subunit TrhA containing 74 residues after cleavage of the signal sequence. Here, we show that the H-pilus forms long filamentous structures that mediate MPF, and describe its cryo electron-microscopic (cryo-EM) structure at 2.2 Å resolution. Like the F pilus, the H-pilin subunits form helical assemblies with phospholipid molecules at a stochiometric ratio of 1:1. While there were previous reports that the T-pilus from Agrobacterium tumefaciens was composed of cyclic subunits, three recent cryo-EM structures of the T-pilus found no such cyclization. Here, we report that the H-pilin is cyclic, with a covalent bond connecting the peptide backbone between the N- and C-termini. Both the cryo-EM map and mass spectrometry revealed cleavage of the last five residues of the pilin, followed by cyclization via condensation of the amine and carboxylate residues. The cyclic nature of the pilin could stabilize the pilus and may explain the high incidence of IncH plasmid dissemination.

Visible Light Photolysis at Single Atom Sites in Semiconductor Perovskite Oxides.

Designing catalysts with well-defined active sites with chemical functionality responsive to visible light has significant potential for overcoming scaling relations limiting chemical reactions over heterogeneous catalyst surfaces. Visible light can be leveraged to facilitate the removal of strongly bound species from well-defined single cationic sites (Rh) under mild conditions (323 K) when they are incorporated within a photoactive perovskite oxide (Rh-doped SrTiO3). CO, a key intermediate in many chemistries, forms stable geminal dicarbonyl Rh complexes (Rh+(CO)2), that could act as site blockers or poisons during a catalytic cycle. For the first time, we demonstrate that CO removal can occur at mild temperatures (323 K) under low-energy red light (635 nm) irradiation, which is not possible for supported isolated-site Rh catalysts (0.2 wt % Rh/γ-Al2O3). Photolysis of supported Rh+(CO)2 complexes (e.g., 0.2 wt % Rh/γ-Al2O3) has been demonstrated but is limited to high energy UV photons. Rigorous kinetic experiments elucidate disparate mechanisms for CO photodepletion from Rh-doped SrTiO3 and supported isolated site Rh/γ-Al2O3. CO photodepletion from supported isolated site Rh/γ-Al2O3 involves a direct metal to ligand charge transfer mechanism, whereas Rh-doped SrTiO3 is governed by electron-hole pair formation in the perovskite. We show that under visible, low-energy red light, surface Rh species in Rh-doped SrTiO3 introduce midgap energy states above the valence band that facilitate electronic excitations leading to surface CO removal. Isolated Rh sites in Rh-doped SrTiO3 also exhibit exceptional stability under multiple CO photodepletion cycles. Overall, incorporating single sites into photoactive perovskite oxides is an effective strategy to influence surface chemistries with visible light.

Specificity of Photochemical Energy Conversion in Photosystem I from the Green Microalga <i>Chlorella ohadii</i>

Primary excitation energy transfer and charge separation reactions in photosystem I (PSI) from the extremophile desert green alga Chlorella ohadii, grown in low light, were studied using broadband femtosecond pump-probe spectroscopy in the spectral range from 400 to 850 nm and in the time range of 50 fs–500 ps. Photochemical reactions were induced by the excitation into the blue and red edges of the chlorophyll Qy absorption band, and compared with similar processes in PSI from the cyanobacterium Synechocystis sp. PCC 6803. When PSI from C. ohadii was excited at a wavelength of 660 nm, the processes of energy redistribution in the light-harvesting antenna of the complex were observed in a time interval of up to 25 ps, while the formation of a stable ion-radical pair P700+A1− was kinetically heterogeneous with characteristic times of 25 and 120 ps. With an alternative variant of excitation into the red edge of the Qy band at a wavelength of 715 nm, in half of the complexes, primary charge separation reactions were observed in the time range of 7 ps. In the rest of the complexes, the formation of the ion-radical pair P700+A1− was limited by energy transfer and occurred with a characteristic time of 70 ps. Similar photochemical reactions in PSI from Synechocystis 6803 were significantly faster: upon excitation at a wavelength of 680 nm, in ~30% of the complexes, the formation of primary ion-radical pairs occurred with a time of 3 ps. Upon excitation at 720 nm, kinetically unresolvable ultrafast primary charge separation was observed in half of the complexes, and the subsequent formation of a P700+A1− ion-radical pair was observed at 25 ps. The photodynamics of PSI from C. ohadii had a noticeable similarity with the processes of excitation energy transfer and charge separation in PSI from the microalga Chlamydomonas reinhardtii; however, in the PSI from C. ohadii slower components in the energy transfer dynamics were also observed.

Genetic variation in Arabidopsis thaliana reveals the existence of natural heat resilience factors for meiosis.

Heat interferes with multiple meiotic processes, leading to genome instability and sterility in flowering plants, including many crops. Despite its importance for food security, the mechanisms underlying heat tolerance of meiosis are poorly understood. In this study, we analyzed different meiotic processes in the Arabidopsis (Arabidopsis thaliana) accessions Columbia (Col) and Landsberg erecta (Ler), their F1 hybrids, and the F2 offspring under heat stress (37°C). At 37°C, Col exhibits significantly reduced formation of double-strand breaks (DSBs) and completely abolished homolog pairing, synapsis, and crossover (CO) formation. Strikingly, Ler and Col/Ler hybrids exhibit normal CO formation and show mildly impacted homolog pairing and synapsis. Interestingly, only 10% ∼ 20% of F2 offspring behave as Ler, revealing that heat tolerance of meiotic recombination in Arabidopsis is genetically controlled by several loci. Moreover, F2 offspring show defects in chromosome morphology and integrity and sister-chromatid segregation, the levels of which exceed those in either inbreds and/or hybrids, thus implying a transgressive effect on heat tolerance of meiosis. Furthermore, correlation and cytogenetic analyses suggest that homolog pairing and/or synapsis have an impact on heat tolerance of chromosome morphology and stability at post-recombination stages. This study reveals natural heat resilience factors for meiosis in Arabidopsis, which have the great potential to be exploited in breeding programs.

Tuning the Duplex Stability of DNA Oligonucleotides Containing Metal-Mediated Base Pairs of Imidazole-Derived Nucleobases.

Two artificial imidazole-derived nucleobases, HQIm (3H-imidazo[4,5-f]quinolin-5-ol) and CaIm (imidazole-4-carboxylate), were introduced into short DNA duplexes to systematically investigate their thermal stability upon metal ion coordination. Metal-mediated base pairs are formed with the 3d metal ions CoII, NiII and ZnII, as well as with the lanthanoid ions EuIII and SmIII, which induce a thermal stabilization of up to 8 °C upon binding. The latter are the first lanthanoid-mediated base pairs involving only four donor atoms that result in a significant duplex stabilization. For the 3d metal ions, the increase in DNA melting temperature is in agreement with the trend in complex stability according to the Irving-Williams series. The duplex stabilization upon metal-mediated base pair formation depends on the identity of the artificial base pair, enabling discrimination between metal ions by systematic design of the duplex. Further, the influence of pH on the stability of selected duplexes was studied, revealing a linear relation between pH and the formation of HQIm-NiII-HQIm base pairs and allowing to induce a distinct stabilization between 1 °C and 28 °C. Regarding EuIII-mediated base pairs, an acidic pH can be utilized to disturb their formation, presumably by promoting the coordination of EuIII to the DNA backbone.

Design of general LQR-ANN-controller of „crane-load” system. Part 1

The first part of the article describes the research concept and presents the results, which in the future allow the development of a LQR-neurocontroller of the movement of the dynamic "crane-load" system. For this purpose, the the problem of optimal control was stated. It uses a mathematical model in which the control function is considered as the rate of driving force change. This increases the order of the system by one. For individual components of the integral criterion, the weight coefficients were chosen and the values of the initial conditions were substantiated. The original problem of the synthesis of a LQR-controller is reduced to the Riccati equation. For one case, a solution to the Riccati equation was obtained and graphic dependencies corresponding to the obtained optimal control were built. The analysis of graphical dependencies made it possible to establish the disadvantages and advantages of the obtained optimal control. Among the advantages are the smoothness of the movement of the system and the provision of a zero value of the driving force at the beginning of the movement. This makes it possible to reduce the dynamic forces of the drive of the crane movement mechanism and its metal structure. Among the disadvantages of optimal control is a significant rate of increase of the driving force at the beginning of the movement, which can cause difficulties in the implementation of optimal control in practice, as well as an overshoot of the crane velocity. Multiple solutions of the Riccati equation made it possible to obtain datasets for training, validation, and testing of an artificial neural network, which is considered as a universal approximator of Riccati equation solutions. The process of data normalization and formation of training pairs is described. All data regarding the optimal values of the controller coefficients were obtained for load masses that varied within 60...25,000 kg and lengths of flexible suspension that varied within 1.2...12 m. In addition, the power of the weight coefficient varied within -5...-30, which corresponds to the minimization of the driving force rate.

High-temperature electrical superconductivity of layered nanoscale “heterostructures”

The paper discusses the possibility of realizing a superconducting state at temperatures of ≈102 K in layered nano-sized heterostructures – thin-film objects consisting of alternating layers of metals and semimetals (or semiconductors) with a thickness of (1–102) nm. The numerical estimates show that in such structures, an increase in the electron density in semimetals (semiconductors) leads to a change in the electrical conductivity up to the appearance of superconductivity. If we assume that superconductivity is realized as a result of electron-phonon interaction, causing the formation of Cooper electron pairs (Bardeen–Cooper–Schrieffer mechanism), then an increase in the electron density in the semiconductor layer of a nano-sized heterostructure should cause an increase in the pairing constant and so-called high-temperature superconductivity can be realized.

Structural determinants of inverted Alu-mediated backsplicing revealed by -MaP and -JuMP.

Biogenesis of circular RNA usually involves a backsplicing reaction where the downstream donor site is ligated to the upstream acceptor site by the spliceosome. For this reaction to occur, it is hypothesized that these sites must be in proximity. Inverted repeat sequences, such as Alu elements, in the upstream and downstream introns are predicted to base-pair and represent one mechanism for inducing proximity. Here, we investigate the pre-mRNA structure of the human HIPK3 gene at exon 2, which forms a circular RNA via backsplicing. We leverage multiple chemical probing techniques, including the recently developed SHAPE- JuMP strategy, to characterize secondary and tertiary interactions in the pre- mRNA that govern backsplicing. Our data confirm that the antisense Alu elements, AluSz(-) and AluSq2(+) in the upstream and downstream introns, form a highly- paired interaction. Circularization requires formation of long-range Alu-mediated base pairs but does not require the full-length AluSq2(+). In addition to confirming long-range base pairs, our SHAPE-JuMP data identified multiple long-range interactions between non-pairing nucleotides. Genome-wide analysis of inverted repeats flanking circular RNAs confirm that their presence favors circularization, but the overall effect is modest. Together these results suggest that secondary structure considerations alone cannot fully explain backsplicing and additional interactions are key.

A Conserved Lysine in an Ion-Pair with a Catalytic Glutamate Is Critical for U-to-C RNA Editing but Restricts C-to-U RNA Editing.

Plants make pyrimidine base substitutions in organellar mRNAs through the action of sequence-specific nuclear-encoded enzymes. Pentatricopeptide repeat (PPR) proteins are essential for ensuring specificity, while the enzymatic DYW domain is often present at the C-terminus of a PPR protein and dependent on the variant possessing C-to-U and/or U-to-C RNA editing activities. Expression of exogenous DYW-KP variant enzymes in bacteria leads to the modification of RNAs suggestive of U-to-C base changes. The modified RNAs could only be purified from the interphase of an acidic guanidinium thiocyanate-phenol-chloroform experiment. It was projected that in bacteria stable RNA-enzyme cross-links form from a lysyl attack. In this study, RNA editing was examined for dual U-to-C/C-to-U editing enzyme KP6 with conserved lysine residues substituted by alanine. A single lysine was found to be essential for U-to-C editing and, based on the crystal structures of DYW domains, would likely be present in the active site. Crystal structures also suggest that the lysine can potentially form an ion pair with the catalytic glutamate critical for C-to-U RNA editing. Mutation of lysine to alanine greatly stimulated the C-to-U RNA editing by KP6. A ∼319 Da adduct observed on DYW-KP proteins could not be detected on the U-to-C-deficient lysine to alanine point mutant enzymes. This work establishes the critical role for a single lysine in the DYW-KP domain specifically for U-to-C editing activity but also highlights a secondary role for the lysine in modulating C-to-U editing through the formation of an inhibitory ion pair with the catalytic glutamate.

Weakly-Supervised Depth Estimation and Image Deblurring via Dual-Pixel Sensors.

Dual-pixel (DP) imaging sensors are getting more popularly adopted by modern cameras. A DP camera captures a pair of images in a single snapshot by splitting each pixel in half. Several previous studies show how to recover depth information by treating the DP pair as an approximate stereo pair. However, dual-pixel disparity occurs only in image regions with defocus blur which is unlike classic stereo disparity. Heavy defocus blur in DP pairs affects the performance of depth estimation approaches based on matching. Therefore, we treat the blur removal and the depth estimation as a joint problem. We investigate the formation of the DP pair, which links the blur and depth information, rather than blindly removing the blur effect. We propose a mathematical DP model that can improve depth estimation by the blur. This exploration motivated us to propose our previous work, an end-to-end DDDNet (DP-based Depth and Deblur Network), which jointly estimates depth and restores the image in a supervised fashion. However, collecting the ground-truth (GT) depth map for the DP pair is challenging and limits the depth estimation potential of the DP sensor. Therefore, we propose an extension of the DDDNet, called WDDNet (Weakly-supervised Depth and Deblur Network), which includes an efficient reblur solver that does not require GT depth maps for training. To achieve this, we convert all-in-focus images into supervisory signals for unsupervised depth estimation in our WDDNet. We jointly estimate an all-in-focus image and a disparity map, then use a Reblur and Fstack module to regularize the disparity estimation and image restoration. We conducted extensive experiments on synthetic and real data to demonstrate the competitive performance of our method when compared to state-of-the-art (SOTA) supervised approaches.

Twin networks in hexagonal close-packed metals: morphology, connectivity, and incompatibilities

The mechanical response of hexagonal close-packed metals is mediated by the formation of three-dimensional twin domain networks. To assess the morphology of these networks and statistically characterize their fingerprint, a three-dimensional twin network in cryogenically compressed high-purity Ti was reconstructed using serial sectioning electron backscatter diffraction (EBSD). Adjoining intergranular twin pairs, high order twin intersections (e.g. triple junctions of twins), and twin network hubs with over 15 separate intergranular and intragranular contacts are found to be salient morphological features of these networks. Using kinematics, the interfacial incompatibilities arising from these twin contact at grain boundaries are studied. The analysis reveals that numerous misaligned paired twin configurations generate high incompatibilities, likely resulting from the contact between two initially distinct twin chains. These configurations generally induce higher incompatibilities than the ones of the individual twins, equivalent to introducing a dense wall of dislocations at twin-grain boundary facets with a dislocation spacing on the order of 1.3 nm or less. In contrast, the shear incompatibilities resulting from the formation of aligned twin pairs are generally reduced compared to non-transmitting twins. Further, twin triple junctions and branches – consisting of intergranular contact of three co-located twins – induce higher incompatibilities on average compared to adjoining twin pairs and represent sources of high shear localization in the domain network.

Aspectual Pair Formation in Russian Verbs: A Cognitive Approach

Aspectual pair formation in Russian verbs represents a core grammatical feature that governs the temporal and contextual framing of actions. Traditional approaches to aspect focus on morphological mechanisms such as prefixation, suffixation, and suppletion, yet they often fail to address irregularities and semantic nuances. This study adopts a cognitive linguistic perspective, exploring how conceptual metaphors, image schemas, and mental mappings underpin aspectual distinctions. By analyzing patterns of pair formation, including both regular and irregular verbs, the research highlights the cognitive processes that align with bounded and unbounded conceptualizations of actions. The findings contribute to linguistic theory by integrating semantic and cognitive frameworks, while practical applications offer innovative strategies for teaching aspect to learners through mental imagery and contextualized learning. Challenges and unanswered questions, such as the treatment of suppletive forms and cross-linguistic comparisons, underscore the need for further interdisciplinary research to refine this approach.