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Formulation development of a biphasic release tablet-in-tablet system containing ketorolac tromethamine
Ketorolac tromethamine (KT) is a potent nonsteroidal anti-inflammatory drug (NSAID) used for moderate to severe pain management. Its short elimination half-life necessitates frequent dosing, which can reduce patient compliance. The objective of this study was to formulate, develop, and optimize a novel biphasic-release tablet-in-tablet (TIT) system for KT to provide immediate pain relief followed by extended drug release. A TIT system was designed, comprising an immediate-release (IR) outer layer and an extended-release (ER) core matrix. The ER core was optimized using a 3 2 full factorial design, with the amounts of HPMC K100M and HPMC K4M as independent variables. Formulations were evaluated for pre- and post-compression parameters, drug-excipient compatibility, and in vitro drug release. The drug release kinetics and mechanism were analyzed using various mathematical models. The optimal ER core formulation (F1) exhibited a drug release of 4.6% at 0.5 h and 66.1% at 12 h, closely matching the theoretical profile (similarity factor f 2 = 51). Release kinetics followed the first-order model and the Korsmeyer-Peppas model indicated an anomalous (non-Fickian) release mechanism (n = 0.831). The corresponding TIT formulation (F11) demonstrated desired physicochemical properties: hardness of 75 N, friability of 0.59%, and rapid outer layer disintegration (<50 s). The TIT provided an initial burst release (~30%) within 30 minutes, followed by sustained release exceeding 90% over 24 hours. This TIT system represents a promising alternative to conventional KT tablets for effective pain management.
Object detection in histology: A multi-dataset benchmark and test-time inference
Medical image analysis has become increasingly important for automated medical diagnosis, as well as deep learning. Specifically, object detection models may help in automatically identifying pathological structures and features. This study presents a comprehensive comparative analysis for object detection tasks in histological images of the latest models including the YOLO (You Only Look Once) architectures, from YOLOv8 to the recently introduced YOLOv12. These models were evaluated alongside alternative architectures including RT-DETR, YOLO-World, and YOLOE across five diverse histology datasets: BCNB, Nuclei, TNBC, MoNuSAC, and CryoNuSeg. The experimental analysis employed standardized training protocols with consistent hyperparameters and data augmentation strategies, evaluating the performance through multiple metrics, inference time, and computational cost. The results obtained on the five datasets indicate that YOLOv11 consistently showed a strong performance across multiple datasets, however the newly introduced attention mechanisms of YOLOv12 show good performance, despite the model having slightly lower overall performance. Specialized variants like YOLOE demonstrated promising results for specific applications, while RT-DETR showed poor performance on smaller objects, which are typical in histological images. Statistical analyses indicate that YOLOv11 indeed has the best performance but that all models have a poor performance on objects of small sizes; moreover, the most common cases of failure are background false positives and missed detections. This comprehensive evaluation provides insights for the current state of object detection architectures for clinical histopathology applications and establishes benchmarks for future avenues of research in automated medical image analysis. In addition to the multi-model benchmark, we propose Test-time Graph Similarity Propagation (TGSP), a test-time self-supervised refinement that uses ResNet50 deep features to build a k-NN similarity graph over detections and performs label propagation to re-score predicted boxes. TGSP replaces TSBP’s iterative Earth-Mover matching with adaptive per-class quantile thresholds and graph-based label propagation, eliminating K-means hyperparameters and better scalability. Our analysis on histology datasets TGSP consistently matches or improves F1 relative to both a fixed 0.5 threshold and TSBP, with the biggest gains when base-model confidence calibration is poor.
Gene-transcription factor regulatory networks implicate primary cilia in the evolution of vertebrate sex determination and expand models of epigenetic regulation
The molecular architecture underlying diverse vertebrate sex-determining systems remains elusive despite fragmentary evidence of changes in upstream regulators and downstream mediators. Here we modeled species-specific regulatory networks of urogonadal development for turtles with contrasting mechanisms [ Apalone spinifera – ZZ/ZW genotypic sex determination (GSD) , and Chrysemys picta – temperature-dependent sex determination (TSD)] using matched data from time-course sampling. We uncovered key steps in the evolutionary transition of sex determination by testing for conservation or divergence of network modular components. Specifically, we tested these alternative hypotheses: first, transcription factor (TF) hubs and their target genes are conserved between species (null H0); second, the same TF hub acquired a new set of target genes in a species, retaining or not ancestral functions (H1 and variants); third, a new TF hub took over the regulation of the former gene targets of an ancestral TF (H2); and finally, complete overhaul occured where both ancestral TF hubs and their target genes were replaced in a species (H3). Results implicate primary cilia as integrators of environmental signals underlying TSD, because known thermosensitive TSD components (e.g., calcium-redox, pSTAT3, Wnt / Rspo1 / β-catenin , Dhh ) overrepresented in our results are linked to primary cilia. TFs that evolved between species also regulate primary cilia and point to key changes in their sensory machinery that accompanied TSD-GSD transitions (e.g., calcium/ion channels or membrane transport components in Chrysemys versus structural elements and ciliogenesis in Apalone ). This novel Primary Cilia Integration hypothesis expands current models of epigenetic regulation of turtle sexual development, the evolution of plasticity versus canalization, and warrants functional validation.
Electrochemical Fluorescence Switching in Rhodamine–Ferrocene Dyads: Spatiotemporal Control in Biomimetic Membranes
Abstract The electrochemical control of fluorescence has been extensively developed in homogeneous media, yet its implementation within electrically insulating lipid bilayers remains largely unexplored. Here we establish that an electrochemically gated fluorescence switch can be implemented in individual giant unilamellar vesicles using a rhodamine–ferrocene dyad that modulates emission through redox-controlled photoinduced electron transfer. A membrane-anchored derivative enables direct visualization of reversible fluorescence activation under electrochemical bias. Remarkably, the switching is strictly leaflet-selective and occurs only for dyads exposed to the electrode interface, highlighting the insulating nature of lipid bilayers. Furthermore, membrane surface charge critically governs the switching efficiency and induces pronounced kinetic asymmetry between oxidation and reduction processes, revealing the key role of interfacial electrostatic interactions in redox-controlled emission. These results establish electrochemical fluorescence modulation in membranes as a spatially and electrostatically gated interfacial process and define general principles for redox-responsive probes operating in soft interfaces, such as lipid membranes.
Supporting recovery: Intersections of health, belonging, and help seeking after a campus mass casualty event
Mass casualty events (MCE), such as campus shootings, can severely impact the mental health of students, faculty, and staff. This study examined the psychological effects of an MCE at a minority-serving institution and explored how sense of belonging, cardiorespiratory fitness, and treatment preferences influenced recovery. To measure the impact of the MCE on mental health an anonymous survey was administered four to five months post-MCE to university students, faculty and staff. Within the survey, participants were asked to retrospectively report their depression (PHQ-9) and anxiety (GAD-7) symptoms as they recalled them two weeks prior to the MCE , and as they experienced them in the two weeks preceding survey completion. The survey also included current measures of sense of belonging (SBS), perceived discrimination (PEDQ), estimated cardiorespiratory fitness (eCRF), and intervention preference to cope with the impacts of the MCE. Participants reported significant perceived increases in PHQ-9 and GAD-7 scores from the pre-MCE recall to current time-periods. Increases in depression (PHQ-9 scores) from pre-MCE to recent recall were larger among respondents with lower pre-MCE anxiety (GAD-7 scores), higher perceived discrimination (PEDQ), and those currently receiving treatment for anxiety or depression; respondents not receiving treatment showed no significant change. Among students, lower belonging scores were associated with greater increases in depression. Neither belonging nor perceived discrimination were strongly linked to individual variables, indicating their multifactorial nature. Most participants reported a preference to learning about alternative interventions such as exercise or meditation over pursuing university counseling services.
Assessing the Impacts of Conformational Fluxionality on Copper(II/I) Electron Transfer Self-Exchange
Abstract Typical Cu(II/I) complexes exhibit hallmark structural changes during their electron transfer (ET) reactions that result from the (pseudo) Jahn-Teller distortions and changes in polarizability inherent to their d9/d10 configurations. Given that such structural changes incur large reorganization energy penalties, the slow rates of ET characteristic of these compounds are unsuprising. However, we recently reported a set of Cu(II/I) complexes that undergo significant and well-defined structural changes during their redox reactions yet exhibit rapid (&gt;105 M–1 s–1) ET self-exchange rate constants (k11). To explain these results, we proposed a pre-equilibrium model in which inherent conformational fluxionality in one of the two oxidation states provides access to pathways involving lower reorganization energies during the ET event. Herein, we report our results testing this hypothesis through the preparation and study of a homologous series of compounds exhibiting varying extents of conformational fluxionality in the Cu(I) state. We characterize these compounds electrochemically, structurally, and by variable temperature NMR spectroscopy to provide experimental evidence for increased fluxionality across the series. We then correlate the trend with increasing k11 through NMR linewidth broadening experiments, further taking care to define the impacts of solvent impurities therein. Finally, the nature of the conformational rearrangements and their relation to increased k11 are explored computationally to reveal differential Boltzmann populations of conformers across the series. The cumulative results of these studies support a previously underappreciated strategy for overcoming barriers to slow ET kinetics: namely through the incorporation of conformational fluxionality.
iNaturalist mammal observations classified by evidence type
Ecologists show growing interest in observational data generated by citizen scientists. For mammals, the largest citizen science platform is iNaturalist, which has more than 5 million Research Grade observations globally represented through images of living animals, dead animals, tracks, and scat. These different types of evidence could give insight into the underlying sampling paradigm for an observation (e.g., dead animals might be more likely to be reported near roads) and thus may be useful for scientific applications of these data. However, while iNaturalist allows users to annotate observations by evidence type, many observations are not annotated. We use machine learning to classify the evidence types associated with observations of North American mammals in iNaturalist, adding metadata that can be used to subset data or to model multiple observation processes. Here, we present a dataset containing metadata augmenting 1.33 million North American mammal iNaturalist observations with evidence type. Each observation is categorized as either live animal, dead animal, tracks, scat, or other sign, and an associated confidence score is provided.
Surface-Confinement Effect Enables Bioorthogonal Drug Release in Tumors
Abstract A critical challenge in the bench-to-bedside translation of controlled drug release strategies is the sharp decline in reaction efficiency as biological complexity increases. A platform capable of maintaining bioorthogonal-like drug release─remaining minimally perturbed by physiological environments─would address an unmet clinical need. This is particularly relevant for radiotherapy-mediated drug release, where the oxidative activation of prodrugs is often compromised by the rapid quenching of reactive intermediates in vivo. Herein, we engineer a hafnium-based nanoscale metal–organic layer platform that leverages a unique “surface-confinement effect” to overcome this challenge. By covalently tethering prodrugs to the Hf-nMOLs surface, we constructed two-dimensional nanoreactors that spatially localize the activation process within an interface enriched with reactive species. This design effectively insulates the activation step from biological scavengers, ensuring efficient payload release efficiency across increasing biological complexity. When loaded with the topoisomerase I inhibitor Exatecan, the Hf-nMOLs system achieved an intratumoral drug-release G-value of 568 nM·Gy−1, resulting in potent radiosensitization and significant tumor-growth suppression under low-dose X-ray irradiation. This work presents a versatile strategy for robust radio-chemotherapeutic combinations, achieving the simultaneous release of diverse payloads activated by radiotherapy. Our findings also suggest that engineering nanoscale surface confinement may provide a generalizable materials strategy to help confer bioorthogonality to otherwise labile activation reactions.
Healthcare providers' perspectives and needs related to the management of Pediatric Feeding Disorder: A focus group study
Pediatric feeding disorder is a prevalent, impactful diagnosis for children and their families. This diagnosis is heterogenous in presentation and requires the care of a multidisciplinary team of providers. Existing research suggests providers are underprepared to assess and treat pediatric feeding disorder, therefore more information on training and clinical practice is needed. This study conducted focus groups to describe the training journey of providers across all four pediatric feeding disorder domains (medical, nutrition, feeding skill, psychosocial). Seven focus groups (total of 25 providers) were conducted and analyzed using thematic analysis. Four themes were identified: differences in academic preparation, workplace infrastructure and access, desire for comprehensiveness and feasibility, and value of the family perspective. Overall, results point to opportunities to improve provider training and therefore patient care including academic exposure to pediatric feeding disorder and multi-disciplinary collaboration practices, increased access to mentorship, training, and evidenced-based resources, and enrichment of the research to practice pipeline with a focus on family-centered care.
Controlled Precursor Differentiation Enables Palladium-Catalyzed Divergent Carbonylation of Cyclobutenols
Abstract Controlling reaction selectivity is a central challenge in synthetic chemistry, particularly when multiple competing reactivity modes coexist within a single substrate. Existing strategies generally rely either on selectivity control during substrate activation or on downstream divergence from a common intermediate. However, these paradigms are less effective when distinct precursor states can independently evolve into distinct reaction manifolds. Herein, we introduce precursor differentiation as a distinct strategy for achieving divergent carbonylation. Through condition-controlled modulation of substrate evolution, a common cyclobutenol substrate can be selectively diverted into two distinct reactive precursors prior to catalytic engagement, thereby enabling access to two different carbonylation pathways. Under palladium catalysis, this strategy enables the highly selective synthesis of either hydroxyl-retained cyclobutanecarboxamides or cyclobutenamides from the same cyclobutenol platform. The method exhibits broad substrate scope (99 examples), consistently high selectivity (&gt;20:1), and compatibility with pharmaceuticals and biologically relevant molecules. Furthermore, the resulting cyclobutenamide products serve as versatile platform intermediates for the selective synthesis of structurally distinct 3-azabicyclo[3.2.0]heptane and 3-azabicyclo[3.1.1]heptane frameworks. Mechanistic studies support a condition-controlled precursor differentiation process prior to carbonylation, providing a conceptual basis for achieving divergent carbonylation through selective control of precursor evolution.
Event-triggered MPC-PID based trajectory tracking control for differential drive mobile robots
Periodic model predictive control (MPC) for differential-drive mobile robots requires online optimization at every sampling instant, which can be redundant during near-steady tracking. This study develops an event-triggered hierarchical MPC–PID framework, termed ET–MPC–PID, to reduce the outer-loop optimization burden while accounting for actuator-side execution effects. The outer MPC updates the velocity setpoint only when a normalized event condition is satisfied or the maximum holding interval is reached. A fixed-period PID-form velocity servo with conditional integration regulates the actuator channel under lag and saturation. The formulation distinguishes holding-induced decision discrepancy from actuator-side mismatch and provides a local practical boundedness characterization. Simulations on double lane-change and figure-eight trajectories compare periodic PID, periodic MPC, periodic MPC–PID, an external variable-horizon ET–MPC reference, and event-triggered ablations. ET–MPC–PID reduces the QP call rate to 16.9% and 22.3% of periodic MPC while outperforming the no-PID event-triggered variant. Sensitivity, Pareto, runtime, and 100-trial Monte Carlo analyses further demonstrate the accuracy–computation trade-off and empirical robustness under sampled execution uncertainty.
Numerical investigation on the mechanical response of steel-frame polyethylene pipelines subjected to strike-slip faulting
This study investigates the failure behavior of buried steel-reinforced polyethylene (SRPE) pipelines crossing strike-slip faults. A high-fidelity three-dimensional pipe-soil interaction model is established using the finite element method, and layered modeling with tie constraints is adopted to replicate the synergistic mechanical characteristics between the PE matrix and steel frame. The effects of pipe-fault intersection angle, steel wire diameter, and soil type on the mechanical response, buckling morphology, and critical strain of the pipeline are systematically examined, and the applicability of three design codes (CSA Z662-2023, GB 50470−2017, EN 13476−3) is quantitatively evaluated. The results show that SRPE pipelines exhibit a three-stage mechanical behavior under fault displacement: elastic bending at small displacement, plastic buckling propagation at moderate displacement, and sectional distortion with global instability at large displacement. The steel frame and PE matrix form an efficient synergistic mechanism featured by “matrix energy dissipation and frame load-bearing”, where failure initiates from plastic deformation of the PE matrix and further induces steel frame yielding and pipeline leakage. The pipe-fault angle dominates the loading pattern: tension is dominant at 30°, while transverse compression at 150° represents the most hazardous condition. The optimal wire diameter ranges from 2.0 to 2.5 mm ; loess provides the strongest constraint, whereas sand is the weakest. Conventional constant strain criteria neglect the angle effect and show obvious limitations in engineering practice. The findings provide significant theoretical support for the seismic design and safety assessment of SRPE pipelines crossing active fault zones.
Enhanced C–F Activation and Proton Supply over Al2O3-Embedded RuO <i>x</i> Clusters Boost Perfluorocarbon Hydrolysis
Abstract The catalytic hydrolysis of per- and polyfluoroalkyl substances (PFAS) holds significant potential for environmental remediation; however, the chemically inert C–F bond poses substantial challenges for achieving efficient low-temperature activity. Herein, we demonstrate that RuOx clusters embedded in mesoporous Al2O3 nanosheet (RuOx/Al2O3) catalysts achieved the complete decomposition of CF4, one of the most chemically inert PFAS, at an unprecedented low temperature of 450 °C, outperforming all catalysts reported to date. The extraordinary CF4 hydrolysis performance is attributed to synergistically enhanced C–F bond activation and proton supply. Specifically, the strong electronic interaction between RuOx clusters and Al2O3 promotes the CF4 adsorption and C–F cleavage on Al sites in RuOx/Al2O3. Furthermore, the Ru sites in RuOx/Al2O3 promote H2O dissociation into *H and *OH, which enables the continuous regeneration of adjacent Al–OH groups and supplies sufficient protons for defluorination in the CF4 hydrolysis reaction. This study paves the way for designing and developing highly efficient catalysts for low-temperature catalytic hydrolysis of PFAS.
Longitudinal changes in laboratory parameters and QTc during isavuconazole therapy in Japanese patients with hematologic malignancies
Background Isavuconazole (ISCZ) is an azole antifungal with a low risk of QTc prolongation and no requirement for renal dose adjustment. However, real-world data in Asian patients remain limited. Methods We retrospectively evaluated 45 patients who received ISCZ between April 2023 and March 2025. Laboratory parameters and QTc values (QTcB/QTcF) were extracted from medical records. Longitudinal changes were assessed using linear mixed-effects models. In patients receiving arsenic trioxide (ATO), QTc trajectories were compared among ATO alone, ATO with ISCZ (ATO-ISCZ), and ATO with other antifungals. Results Grade ≥2 elevations in AST and ALT occurred in 11.1% and 13.3% of patients, respectively, and were transient. No significant deterioration in laboratory parameters was observed. In the ATO subgroup, QTc values in the ATO-ISCZ group were lower than those in the ATO group from Day 30, with the largest difference at Day 70 (−45.5 ms for QTcB and −42.3 ms for QTcF; both p < 0.001). The ATO–other antifungals group showed similar trends to the ATO group. No clinically significant cardiac events were observed. Conclusions ISCZ showed a favorable safety profile in Japanese patients with hematologic malignancies and may be a safe option during QT-prolonging therapies.
3,5-Bis(2-hexafluoro-isopropoxyl)phenyl: A Super-Fluorinated Moiety with Favorable Water-Solubility and Modifiability for 19F Magnetic Resonance Imaging
Abstract Among molecular imaging techniques, 19F magnetic resonance imaging (19F MRI) is particularly attractive due to deep penetration and multiplexed molecular imaging. However, the further development of 19F MRI remains constrained by its limited sensitivity, which largely depends on fluorinated probe design and more fundamentally on the availability of high-performance fluorinated moieties that define probe signal intensity. Here we systematically establish 3,5-bis(2-hexafluoro-isopropoxy)phenyl (BHFIP) as a structurally simple yet highly capable fluorinated moiety for 19F MRI probe design. Starting from 1,3-bis(2-hexafluoro-isopropoxy)benzene, a simple two-step nitration-reduction procedure afforded 3,5-bis(2-hexafluoro-isopropoxy)aniline (BHFIP-NH2), a modifiable BHFIP-based building block. Besides its high fluorine loading of 12 chemically equivalent fluorine atoms, BHFIP was found to possess an intrinsically short 19F longitudinal relaxation time (T1), together enabling exceptionally high 19F MRI sensitivity. Its 19F chemical shift at approximately – 75 ppm is clearly distinguishable from those of established highly fluorinated moieties, supporting multiplexed 19F MRI. The two hydroxyl groups of BHFIP contribute to water solubility and enable O-modification, while BHFIP-NH2 further provides an additional amino handle for N-modification. Representative incorporation of BHFIP-NH2 into 19F MRI probes further verified that the advantages of BHFIP can be retained in functional probe molecules. This work establishes BHFIP as a promising fluorinated moiety for high-sensitive and multifunctional 19F MRI probes.
Expert-guided optimization for load transfer in distribution networks assisted by virtual power plants
The rapid expansion of distribution networks and the increasing complexity of their topological structures pose significant challenges to fast and reliable post-fault service restoration. Meanwhile, driven by carbon neutrality goals, the large-scale integration of distributed energy resources (DERs) enhances operational flexibility but also introduces pronounced intermittency and uncertainty, further complicating post-fault load transfer decision-making. To address these challenges, this paper proposes an expert-guided and virtual power plant (VPP)-assisted load transfer optimization framework based on hierarchical graph reinforcement learning. A topology-aware graph neural network (GNN)–based state representation is developed, in which buses are modeled as nodes and switches as controllable edges, enabling explicit modeling of network connectivity and electrical coupling. On this basis, a hierarchical decision-making architecture is constructed: the upper-level agent, guided by expert knowledge, dynamically selects the restoration task type to coordinate the timing of network reconfiguration and VPP-assisted DER regulation; driven by this high-level directive, two specialized lower-level agents respectively execute the specific switch operations and stepwise DER power adjustments, ensuring power balance and voltage security. Simulation results on a practical distribution network demonstrate that, under high DER penetration, the proposed method achieves faster service restoration, higher load recovery ratios, and significantly fewer voltage violation events than conventional reinforcement learning approaches, exhibiting improved operational safety and scheduling stability.
Redox-Active Poly( <scp>l</scp> -lysine) as a Cathode toward Sustainable Sodium-Ion Batteries
Abstract The advancement of sustainable sodium-ion batteries (SIBs) necessitates cathode materials that exhibit exceptional electrochemical performance and environmentally benign end-of-life degradability. However, achieving this balance remains challenging in degradable material systems due to the intrinsic trade-off between electronic delocalization, ion transport, and structural stability. Here we report a redox-active polypeptide platform featuring a poly(l-lysine) (PLL) scaffold cross-linked with aromatic dianhydrides of varying core sizes. By enabling a “core-size modulation” strategy, this design simultaneously tunes π-conjugation and porosity, thereby coupling electronic delocalization with Na-ion transport and preserving degradability. Consequently, a poly(l-lysine)–perylenetetracarboxylic dianhydride (PLL-PTCDA or P-PT) cathode exhibits a high reversible capacity of 136.8 mAh g–1 at 50 mA g–1 and stable cycling over 15,000 cycles at 1 A g–1. Mechanistic analyses indicate that an increase in the aromatic core size promotes electronic delocalization, while enhanced porosity facilitates Na-ion transport. This combination enables reversible multielectron storage with suppressed dissolution and robust structural integrity. More importantly, the polypeptide scaffold retains intrinsic degradability, enabling chemical or enzymatic degradation once the cathode reaches its end of life. This work establishes a modular molecular-design principle that integrates electrochemical durability with programmed degradability, providing a circular pathway toward lifecycle-aware organic cathodes in next-generation sustainable SIBs.
The mechanism and dynamics of the sedimentation of styrene/divinylbenzene microplastics from water and the solidification of the precipitate with an alum-based coagulant “BUCOCHEM”
Although publications on the efficiency of various coagulants in removing microplastic contamination from water are quite abundant, detailed information on the coagulation/sedimentation mechanisms and dynamics, and on the formation of microplastic particle flocs, is less common. In this article, the mechanism and dynamics of coagulation, flocs formation, and sedimentation of styrene/divinylbenzene microplastic particles sized between 400 and 500 µm from water with the use of an alum-based coagulant “BUCOCHEM” have been investigated. The research has been conducted using jar tests to study coagulation/sedimentation dynamics and visual microscopic observations to examine floc formation. It was found that this coagulant promotes better sedimentation and compaction of the plastic particles, ensuring the formation of a dense, more stable, and easily removable precipitate layer. A 0.1 wt % of the coagulant leads to a decrease in the height of the polymer sediment layer by 14% after 48 hours, as compared to the coagulant-free sedimentation. Furthermore, the former sediment appears more compact and stable. Even the lower 0.05–0.07 wt% of BUCOCHEM ensures the formation of three-dimensional flocs, which sediment into a compact and stable precipitate layer, effectively resisting secondary resuspension. Although such concentrations of BUCOCHEM lead to some decrease in the sedimentation rate (from 3.5 to 2.5–2.7 mm/s), it is more important that the resulting precipitate layer becomes more compact and stable against secondary resuspension than without the coagulant. The process of the precipitate layer compacting and solidification is mostly complete within 24 h. These results indicate the most optimal concentration of BUCOCHEM (0.05–0.07 wt%) and seem useful for potential application of this coagulant to treat water/wastewater for the removal of microplastic contamination.
Stereodynamism in Pentacoordinate Al(Salen) Catalysts
Abstract M(Salen) complexes are totemic in asymmetric catalysis on account of the generality and selectivity that they confer. Consequently, the development of unifying models to place the function of these disruptive actors on a structural foundation is essential to sustain innovation. Motivated by the transformative effect that the Jacobsen catalyst (M = Al) has had on contemporary synthesis, a thorough three-dimensional structural investigation of the solution phase behavior of Al(Salen) complexes is reported, and complemented by solid-state 27Al MAS NMR and computational investigations. This interdisciplinary analysis of the venerable Al(Salen)Cl complex reveals a rapid equilibrium of R,R-(M) and R,R-(P) species in solution enabled by intermolecular halide-catalyzed rearrangements. Contrary to established models, the backbone remains in the trans-diequatorial conformation: the antipodal (axial) configurations (M/P) are enforced by a change in coordination geometry between square based pyramidal (sbp) and distorted trigonal bipyramidal (dtbp). The occurrence of orthogonal helical diastereomers, with conserved point chirality [R,R-(M) and R,R-(P)] converges on a revised model to describe the behavior of pentacoordinate M(Salen) complexes based on the Addison geometry parameter τ. Stereodynamism resulting from dynamic metal coordination geometry is determined to be a key parameter that should be considered in future reaction design and induction models. It is envisaged that this intriguing behavior of pentacoordinate Al(Salen) complexes will find application beyond asymmetric catalysis.
Discovering search behaviour in black garden ant trajectories
Exploratory behaviour plays an important role in many animals, in particular for social insects who have to feed and protect a whole colony. In a laboratory study, Khuong et al (2013) studied how workers of the black garden ant Lasius niger move around in an unknown environment. They assumed that, in a homogeneous arena with no visual cues, ants had no information about their position in space. Based on this hypothesis, they modelled ant movement in a Boltzmann Walker framework which describes an ant’s random walk as a series of straight segments separated by reorientation events. They found that, on a plain horizontal surface, an ant’s heading does not influence its speed, segment length and reorientation decision, thus leading to diffusive trajectories. However, published experiments indicate that L. niger ants are not completely devoid of directional information, even in standard laboratory setups with no obvious visual landmarks. Moreover, many ant species are known to develop specific search strategies when they want to find a particular place in space, a situation that may apply to the data Khuong el al analysed. We re-analysed their data on a plain horizontal surface, this time taking into account the ant’s heading in relation to its starting point in the arena. We discovered that the distributions of segment lengths and reorientation angles are modulated by the ant’s orientation in relation to its starting point. By simulating these biased trajectories, we show that this modulation leads to an area-restricted search behaviour. We also show that this modulation considerably accelerates the return times of ants to their starting point when they find themselves far from it. We conclude that not taking into account the animal’s cognitive abilities in data analysis may lead to incomplete or biased conclusions. The discovered search behaviour in L. niger can play a significant role in the colony’s exploration and foraging ecology.