Similar Interactions Research Articles

Apatite–Calcite Flotation Separation Using Sodium N-Lauroylsarcosinate as a Selective Collector

Froth flotation is a commonly utilized beneficiation technique for effectively separating apatite from other gangue minerals, such as calcite. It is difficult to achieve good separation with fatty acid collectors due to their similar interactions with apatite and calcite. In this work, sodium N-lauroyl sarcosinate (SNLS) was used as the collector for the selective separation of calcite from apatite without a depressant. The experiments revealed that SNLS had a much better selectivity and a stronger affinity with calcite compared to apatite, with little effect on the flotation of apatite observed at a pH of 10. Fourier transform infrared (FTIR) analyses were conducted to explain the selective collector process of SNLS. The mechanism experiments demonstrate that SNLS can chemically bond to apatite and calcite minerals to produce Ca-NLS chelates. The active O atoms of the amide and carboxyl groups of SNLS accomplish this. Calcite has a greater Ca-reactivity than apatite, and as a result, the adsorption quantity on the calcite surface is greater than that on the apatite surface. FTIR analyses indicate that SNLS exhibits a greater affinity for the calcite surface than for apatite, a finding that is supported by first-principle density functional theory (DFT) calculations showing a higher adsorption energy of SNLS on the calcite surface. DFT calculations showed that SNLS forms stronger O-Ca bonds on the calcite surface and is less hindered by H2O. This work shows that the surfactant sodium N-lauroylsarcosinate (SNLS) can be an ideal collector for the flotation of phosphate minerals.

The Factor beyond Schmidt's Criteria Impacting the Photo-Induced [2+2] Cycloaddition Reactivity and Photoactuation of Molecular Crystals Based on Cyclic Chalcone Analogues.

Generally, the potential reactive "olefin pairs" in the molecular crystals satisfying Schmidt's criteria could undergo topological [2+2] cycloaddition. In this study, another factor that affects the photodimerization reactivity of chalcone analogues was found. The cyclic chalcone analogues of (E)-2-(2,4-dichlorobenzylidene)-2,3-dihydro-1H-inden-1-one (BIO), (E)-2-(naphthalen-2-ylmethylene)-2,3-dihydro-1H-inden-1-one (NIO), (Z)-2-(2,4-dichlorobenzylidene)benzofuran-3(2H)-one (BFO), and (Z)-2-(2,4-dichlorobenzylidene)benzo[b]thiophen-3(2H)-one (BTO) have been synthesized. While the geometrical parameters for the molecular packing of the above four compounds did not exceed Schmidt's criteria, [2+2] cycloaddition did not occur in the crystals of BIO and BTO. The single crystal structures and Hirshfeld surface analyses revealed that interactions of C=O⋅⋅⋅H (CH2 ) existed between adjacent molecules in the crystal of BIO. Therefore, the carbonyl and methylene groups linked with one carbon atom in carbon-carbon double bond were tightly confined in the lattice, acting as a tweezer to inhibit free movement of the double bond and suppressing [2+2] cycloaddition. In the crystal of BTO, similar interactions of Cl⋅⋅⋅S and C=O⋅⋅⋅H (C6 H4 ) prevented free movement of the double bond. In contrast, the intermolecular interaction of C=O⋅⋅⋅H only exists around the carbonyl group in the crystals of BFO and NIO, leaving the C=C double bonds to move freely and allowing the occurrence of [2+2] cycloaddition. Driven by photodimerization, the needle-like crystals of BFO and NIO displayed evident photo-induced bending behavior. This work demonstrates that the intermolecular interactions around carbon-carbon double bond affect the [2+2] cycloaddition reactivity except for Schmidt's criteria. These findings provide valuable insights into the design of photomechanical molecular crystalline materials.

A Bayesian actor-oriented multilevel relational event model with hypothesis testing procedures

AbstractRelational event network data are becoming increasingly available. Consequently, statistical models for such data have also surfaced. These models mainly focus on the analysis of single networks; while in many applications, multiple independent event sequences are observed, which are likely to display similar social interaction dynamics. Furthermore, statistical methods for testing hypotheses about social interaction behavior are underdeveloped. Therefore, the contribution of the current paper is twofold. First, we present a multilevel extension of the dynamic actor-oriented model, which allows researchers to model sender and receiver processes separately. The multilevel formulation enables principled probabilistic borrowing of information across networks to accurately estimate drivers of social dynamics. Second, a flexible methodology is proposed to test hypotheses about common and heterogeneous social interaction drivers across relational event sequences. Social interaction data between children and teachers in classrooms are used to showcase the methodology.

Effects of Cerebrovascular and Lewy Body Pathology on Parkinsonian Signs in Community-Dwelling Older Adults.

The roles of Lewy body (LB) and separately of cerebrovascular disease (CVD) pathologies in the severity of parkinsonian signs are well recognized in old age. We investigated whether the 2 pathologies act synergistically to further potentiate the severity of parkinsonism beyond their separate effects. We used postmortem data of decedents from 3 longitudinal community-based studies of aging who underwent annual clinical evaluation to assess parkinsonian signs using 26 items of the motor portion of a modified Unified Parkinson Disease Rating Scale. A summary score was developed from each item score to construct a global parkinsonian score, with a higher score indicating more severe parkinsonism. A detailed neuropathologic evaluation was performed to identify LB, Alzheimer disease pathology, nigral neuronal loss, atherosclerosis, macroscopic infarcts, and other CVD pathologies (arteriolosclerosis, cerebral amyloid angiopathy, and microscopic infarcts). A series of regression models with terms for LB, CVD pathology, and the interaction of LB with CVD pathologies was fit for global parkinsonism proximate to death and for individual parkinsonian signs scores including, parkinsonian gait, rigidity, tremor, and bradykinesia. In 1,753 participants (mean age at death = 89 years; 68% women), LB was observed in 26% of participants, and CVD pathologies were present in more than two-thirds of participants. LB and 3 CVD pathologies (atherosclerosis, arteriolosclerosis, and macroscopic infarcts) were each independently associated with the severity of global parkinsonism proximate to death (LB: β = 0.318, SE = 0.08, p < 0.001; atherosclerosis: β = 0.373, SE = 0.079, p < 0.001; arteriolosclerosis: β = 0.253, SE = 0.078, p = 0.001; macroscopic infarcts: β = 0.333, SE = 0.077, p < 0.001). A linear regression model adjusted for demographics, CVD, and neurodegenerative pathologies showed interaction between LB and macroscopic infarcts (β = 0.463, SE = 0.168, p = 0.006), with LBs being associated with worse global parkinsonism when macroinfarcts are present. Similar interactions were found for atherosclerosis and LBs (β = 0.371, SE = 0.173, p = 0.032) and for parkinsonian gait as the outcome (macroscopic infarcts: β = 0.662, SE = 0.239, p = 0.005; atherosclerosis: β = 0.509, SE = 0.246, p = 0.038). Findings were not affected when the 66 participants with a clinical diagnosis of Parkinson disease were excluded. By contrast, there were no interactions between LB and other CVD pathologies or between atherosclerosis and macroscopic infarcts for global parkinsonism proximate to death. These findings suggest that atherosclerosis and macroscopic infarcts interact with LB pathology to increase the severity of parkinsonism beyond their additive effects in older persons.

Life expectancy after bariatric surgery or usual care in patients with or without baseline type 2 diabetes in Swedish Obese Subjects.

To determine life expectancy and causes of death after bariatric surgery in relation to baseline type 2 diabetes (T2D) in the prospective, Swedish Obese Subjects study. The study included 2010 patients with obesity who underwent bariatric surgery and 2037 matched controls, eligible for surgery. The surgery group underwent gastric bypass (n = 265), banding (n = 376), or vertical banded gastroplasty (n = 1369). The control group (n = 2037) received usual obesity care. Causes of death were obtained from the Swedish Cause of Death Register, case sheets and autopsy reports, in patients with baseline T2D (n = 392 surgery patients/n = 305 controls) or non-T2D (n = 1609 surgery patients/n = 1726 controls) during a median follow-up 26 years. In T2D and non-T2D subgroups, bariatric surgery was associated with increased life expectancy (2.1, 95% confidence interval (95% CI) 0.2-4.0; and 1.6, 0.5-2.7 years, respectively) and reduced overall mortality (adjusted hazard ratio (adjHR) = 0.77, 95% CI: 0.61-0.97; and 0.82, 0.72-0.94, respectively), and the treatment benefit was similar (interaction p = 0.615). Bariatric surgery was associated with reduced cardiovascular mortality in both subgroups (adjHR = 0.65, 95% CI: 0.46-0.91; and 0.70, 0.55-0.88, respectively (interaction p = 0.516)). Bariatric surgery is associated with similar reduction of overall and cardiovascular mortality and increased life expectancy regardless of baseline diabetes status.

An exploration of communication skills development for student diagnostic radiographers using simulation-based training with a standardised patient: UK-based focus-group study

IntroductionCommunication is an essential skill for all healthcare professionals but is particularly challenging for diagnostic radiographers since their role involves conveying extensive information within a relatively short amount of time. One method to develop communication skills in radiography is through simulation-based training using high fidelity simulation activities. The use of video recording for reflection and debriefing are also important elements that can be utilised to enhance learning. The aim of this project was to explore student radiographers’ experiences of a simulation-based activity utilising a standardised patient designed to aid development of communication skills. MethodsFifty-two undergraduate 3rd year diagnostic radiography students at a single Higher Education Institution undertook a simulation roleplay exercise with an expert by experience (EBE) who acted in an anxious manner in order to challenge the student's communication skills following the simulation, students received a debrief session where detailed feedback was provided from the EBE and an academic. Students were also able to watch their video of the simulation and reflect. Students were invited to participate in a focus group to discuss their experience and the learning they had developed and 12 students participated. Transcribed material from the focus groups was thematically analysed to deduce themes of learning developed and ways to improve for future simulations. FindingsSix main themes were identified from the thematic analysis of the transcripts from 12 diagnostic radiography students. These were patient care, radiographer's role and responsibilities, personal development, feelings, fidelity, and pedagogy. The themes represented the key learning points expressed by students and also aspects of the simulation which could be improved.Overall, the simulation provided a positive learning experience for the students. Having a video recording of the scenario was regarded as beneficial to enable a depth of reflection on non-verbal communication skills, which would be beneficial in future simulation scenarios. Students were aware that even though they used appropriate language their overall manner affected the interaction with the expert by experience more significantly. Students also considered methods to improve their communication if they encountered a similar patient interaction in their future practice. ConclusionThere is great potential for simulation-based training in developing communication skills for diagnostic radiography students. EBEs are a vital addition to simulation and educational activities in Higher Education Institutions and should be involved with the design of simulation activities also, as they can bring unique patient insight.

Comparative analysis of a POPC bilayer and a DPC micelle comprising an interfacial anchored peptide using all-atom MD simulations

Abstract Biological membranes are complex systems due to their composition and dynamics. Therefore, membrane mimetics are widely used to investigate lipid properties and interactions between molecules and membrane lipids. Using all-atom molecular dynamics simulations, within this study two systems composed of different membrane mimetics are compared: a 1-palmitoyl-2-oleoyl-3-glycero-phosphatidylcholine (POPC) bilayer or a dodecylphosphocholine (DPC) micelle and a nonapeptide (V94-T-K-Y-W-F-Y-R-L102). Previous 1H-NMR experiments have demonstrated that, in the presence of DPC micelles, this peptide folds as a stable amphipathic helix located in the polar head group region with the tryptophan residue pointing toward the inside of the micelle. The present comparison reveals a hydrophobic surface twice as large for the micelle as for the bilayer and a different arrangement of the acyl chains. The peptide secondary structure is not strongly affected by the membrane mimetics whereas the peptide is more deeply inserted in the bilayer than in the micelle. The contacts between the peptide and the DPC or POPC molecules are analysed and although the distances and lifetimes of these contacts are very different in the micelle and the bilayer, similar specific interactions were found that mainly involved the side chains of the residues R101 and L102.

Genome-wide identification and expression analysis of the AUX/IAA gene family in turnip (Brassica rapa ssp. rapa)

BackgroundAuxin/indoleacetic acid (AUX/IAA) genes encoding short-lived proteins participate in AUX signaling transduction and play crucial roles in plant growth and development. Although the AUX/IAA gene family has been identified in many plants, a systematic analysis of AUX/IAA genes in Brassica rapa ssp. rapa has not yet been reported.ResultsWe performed a comprehensive genome-wide analysis and found 89 AUX/IAA genes in turnip based on the conserved AUX/IAA domain (pfam02309). Phylogenetic analysis of AUX/IAA genes from turnip, Arabidopsis, and cabbage revealed that these genes cluster into six subgroups (A1, A2, A3, A4, B1, and B2). The motif distribution was also conservative among the internal members of the clade. Enhanced yellow fluorescent protein (EYFP) signals of BrrIAA-EYFPs showed that BrrIAA members functioned as nucleoproteins. Moreover, transcriptional analysis revealed that the expression patterns of AUX/IAA genes in turnip were tissue-dependent. Because orthologs have similar biological functions and interaction networks in plant growth and development, BrrIAA66 in turnip possibly played a role in embryo axis formation, vascular development, lateral root formation, and floral organ development by interacting with BrrARF19 and BrrTIR1.ConclusionThese results provide a theoretical basis for further investigation of BrrAUX/IAA genes and lay the foundation for functional analysis of BrrIAA66 in turnip.

Methylammonium Tetrel Halide Perovskite Ion Pairs and Their Dimers: The Interplay between the Hydrogen-, Pnictogen- and Tetrel-Bonding Interactions.

The structural stability of the extensively studied organic-inorganic hybrid methylammonium tetrel halide perovskite semiconductors, MATtX3 (MA = CH3NH3+; Tt = Ge, Sn, Pb; X = Cl, Br, I), arises as a result of non-covalent interactions between an organic cation (CH3NH3+) and an inorganic anion (TtX3-). However, the basic understanding of the underlying chemical bonding interactions in these systems that link the ionic moieties together in complex configurations is still limited. In this study, ion pair models constituting the organic and inorganic ions were regarded as the repeating units of periodic crystal systems and density functional theory simulations were performed to elucidate the nature of the non-covalent interactions between them. It is demonstrated that not only the charge-assisted N-H···X and C-H···X hydrogen bonds but also the C-N···X pnictogen bonds interact to stabilize the ion pairs and to define their geometries in the gas phase. Similar interactions are also responsible for the formation of crystalline MATtX3 in the low-temperature phase, some of which have been delineated in previous studies. In contrast, the Tt···X tetrel bonding interactions, which are hidden as coordinate bonds in the crystals, play a vital role in holding the inorganic anionic moieties (TtX3-) together. We have demonstrated that each Tt in each [CH3NH3+•TtX3-] ion pair has the capacity to donate three tetrel (σ-hole) bonds to the halides of three nearest neighbor TtX3- units, thus causing the emergence of an infinite array of 3D TtX64- octahedra in the crystalline phase. The TtX44- octahedra are corner-shared to form cage-like inorganic frameworks that host the organic cation, leading to the formation of functional tetrel halide perovskite materials that have outstanding optoelectronic properties in the solid state. We harnessed the results using the quantum theory of atoms in molecules, natural bond orbital, molecular electrostatic surface potential and independent gradient models to validate these conclusions.

SAELGMDA: Identifying human microbe-disease associations based on sparse autoencoder and LightGBM.

Identification of complex associations between diseases and microbes is important to understand the pathogenesis of diseases and design therapeutic strategies. Biomedical experiment-based Microbe-Disease Association (MDA) detection methods are expensive, time-consuming, and laborious. Here, we developed a computational method called SAELGMDA for potential MDA prediction. First, microbe similarity and disease similarity are computed by integrating their functional similarity and Gaussian interaction profile kernel similarity. Second, one microbe-disease pair is presented as a feature vector by combining the microbe and disease similarity matrices. Next, the obtained feature vectors are mapped to a low-dimensional space based on a Sparse AutoEncoder. Finally, unknown microbe-disease pairs are classified based on Light Gradient boosting machine. The proposed SAELGMDA method was compared with four state-of-the-art MDA methods (MNNMDA, GATMDA, NTSHMDA, and LRLSHMDA) under five-fold cross validations on diseases, microbes, and microbe-disease pairs on the HMDAD and Disbiome databases. The results show that SAELGMDA computed the best accuracy, Matthews correlation coefficient, AUC, and AUPR under the majority of conditions, outperforming the other four MDA prediction models. In particular, SAELGMDA obtained the best AUCs of 0.8358 and 0.9301 under cross validation on diseases, 0.9838 and 0.9293 under cross validation on microbes, and 0.9857 and 0.9358 under cross validation on microbe-disease pairs on the HMDAD and Disbiome databases. Colorectal cancer, inflammatory bowel disease, and lung cancer are diseases that severely threat human health. We used the proposed SAELGMDA method to find possible microbes for the three diseases. The results demonstrate that there are potential associations between Clostridium coccoides and colorectal cancer and one between Sphingomonadaceae and inflammatory bowel disease. In addition, Veillonella may associate with autism. The inferred MDAs need further validation. We anticipate that the proposed SAELGMDA method contributes to the identification of new MDAs.

Cortical facilitation of tactile afferents during the preparation of a body weight transfer when standing on a biomimetic surface.

Self-generated movement shapes tactile perception, but few studies have investigated the brain mechanisms involved in the processing of the mechanical signals related to the static and transient skin deformations generated by forces and pressures exerted between the foot skin and the standing surface. We recently found that standing on a biomimetic surface (i.e., inspired by the characteristics of mechanoreceptors and skin dermatoglyphics), that magnified skin-surface interaction, increased the sensory flow to the somatosensory cortex and improved balance control compared to standing on control (e.g., smooth) surfaces. In this study, we tested whether the well-known sensory suppression that occurs during movements is alleviated when the tactile afferent signal becomes relevant with the use of a biomimetic surface. Eyes-closed participants (n = 25) self-stimulated their foot cutaneous receptors by shifting their body weight toward one of their legs while standing on either a biomimetic or a control (smooth) surface. In a control task, similar forces were exerted on the surfaces (i.e., similar skin-surface interaction) by passive translations of the surfaces. Sensory gating was assessed by measuring the amplitude of the somatosensory-evoked potential over the vertex (SEP, recorded by EEG). Significantly larger and shorter SEPs were found when participants stood on the biomimetic surface. This was observed whether the forces exerted on the surface were self-generated or passively generated. Contrary to our prediction, we found that the sensory attenuation related to the self-generated movement did not significantly differ between the biomimetic and control surfaces. However, we observed an increase in gamma activity (30-50 Hz) over centroparietal regions during the preparation phase of the weight shift only when participants stood on the biomimetic surface. This result might suggest that gamma-band oscillations play an important functional role in processing behaviorally relevant stimuli during the early stages of body weight transfer.

XRSpotlight: Example-based Programming of XR Interactions using a Rule-based Approach

Research on enabling novice AR/VR developers has emphasized the need to lower the technical barriers to entry. This is often achieved by providing new authoring tools that provide simpler means to implement XR interactions through abstraction. However, novices are then bound by the ceiling of each tool and may not form the correct mental model of how interactions are implemented. We present XRSpotlight, a system that supports novices by curating a list of the XR interactions defined in a Unity scene and presenting them as rules in natural language. Our approach is based on a model abstraction that unifies existing XR toolkit implementations. Using our model, XRSpotlight can find incomplete specifications of interactions, suggest similar interactions, and copy-paste interactions from examples using different toolkits. We assess the validity of our model with professional VR developers and demonstrate that XRSpotlight helps novices understand how XR interactions are implemented in examples and apply this knowledge in their projects.

Computational determination of the solvation structure of LiBF4 and LiPF6 salts in battery electrolytes

Li-ion battery technology has come a long way since its initial development a few decades ago. However, expectations of energy storage continue to grow, making the optimization of battery technology vital. Along with improving the electrochemical performance of electrodes, investigation of the properties of the electrolyte has thus become necessary. In this work, we use first principles computational modeling to investigate the structural and physical interactions of a common solvent solution, ethylene carbonate:dimethyl carbonate, with two salts, LiPF6 and LiBF4. We look at how the solvation shells form and evolve using ab initio molecular dynamics (AIMD) simulations. The solvation structures extracted from the calculated trajectories are used to investigate the energetics of removal of individual solvent molecules using density functional theory (DFT). We also investigate the order in which the solvent molecules form a shell around the salts. LiBF4 and LiPF6 have similar solvation structures and interaction energies with the solvent, with a preference for the carbonyl oxygens and the ether oxygens to interact with the Li+ cations, and the methyl or methylene groups to interact with the BF4− or PF6− anions. Our calculations also find that the solvation shell formed around LiPF6 can desolvate more easily compared to LiBF4, suggesting easier kinetics/diffusion.

Exploring the Pygmalion Phenomenon in a Male-Centric Industry and Developing a Model of Female Career Progression

This paper explores the relationship between the Pygmalion Effect and female career progression. The data was collected from sales representatives in the real estate sector in Pakistan through semi-structured interviews. Data was analyzed using Quirkos 2.5.3. The results of thematic analysis revealed that male employees received preferential treatment due to their perceived self-efficacy, leading managers to invest more in their development, which can be linked to the Pygmalion Effect. In contrast, female employees did not receive the same treatment within the real estate sector. The findings recommend that top management in the real estate sector should maintain similar interactions with all employees, regardless of their gender, to avoid sub-group formation. Conducting exit interviews with female employees can help identify underlying issues that contribute to their departure from organizations. This paper fills a gap in the existing literature by developing a model for understanding the role of the Pygmalion Effect in female career progression.

Dispersion interactions with analytes at the center of graphene nanoflakes turn into electrostatic at the edge

Adsorption of small gaseous molecules on the center and edges of polycyclic aromatic hydrocarbons is studied through density functional theory calculations. The choice of selected functional for the study is based on a benchmarking, where 37 functionals are evaluated at low cost basis set against high level DFT SAPT calculations for adsorption of water molecule on coronene and hexabenzocoronene. After benchmarking, the detailed analysis is performed for the adsorption of H2S, H2O, NH3, CH3OH, HCN, H2O2 and NH2NH2 on coronene at its center and edges. The coronene is chosen to better elucidate the edge effect on the adsorption of analytes. All of the studied analytes are physiosorbed on coronene with adsorption energies ranging from 1 to 6 kcal mol−1. These complexes are stabilized by X-H---π interactions between analytes and coronene surface. The SAPT0 analysis reveals that the X-H---π interactions at the center (non-edge) position of coronene are dominated by dispersion interaction whereas the similar interactions at the edges are dominated by electrostatic interactions. The change from dispersion to electrostatic on edges is attributed to polarization of the systems by C–H polarity differences. The complexes having lone pair---π interactions have unexpectedly repulsive electrostatic interactions in H2S@GNF and NH3@GNF complexes. Electronic properties reveal that coronene surface is highly selective for hydrazine whereas adsorption of other analytes does not bring any significant changes in the electronic structure of coronene. The high selectivity of coronene for NH2NH2 is also evident from the redistribution of densities in frontier molecular orbitals. For NH2NH2@GNF complexes, the HOMOs are present on hydrazine whereas LUMOs are present in coronene. For other analytes, HOMOs and LUMOs are present merely on graphene nanoflake. This high sensitivity of coronene for hydrazine is due to better overlap of frontier molecular orbitals of analyte with coronene.

IGF‐I modulation of emotion and social interaction through Locus Coeruleus in aging and AD mice

AbstractBackgroundInsulin‐like Growth Factor I (IGF‐I) is a peptide involved in many processes in the brain. Recently, we described how IGF‐I modulates sleep behavior, response to stress, and its role in cognition through cholinergic, orexinergic, and locus coeruleus nuclei. Nonetheless, IGF‐I modulation of social behavior remains explored, especially during aging and Alzheimer’s disease pathology. This study aims to determine how IGF‐I modulates emotion and social behavior through Locus Coeruleus activity in young (&lt;6m), middle‐aged (&lt;12m, and old control (&gt;18m), transgenic APP/PS1 and DPS‐4 mice, from the same ages.MethodWe use extensive behavioral testing of cognition (Y Maze spontaneous activity) and emotion (Forced Swim Test, Elevated Plus Maze), social interaction (Social affiliation and social novelty/Preference), and another test. We also use electrophysiology to determine LC responses to IGF‐I as DPS‐4 neurotoxin to evaluate the role of LC in emotion and social interaction.ResultsWe now report that social behavior is reduced through aging in control mice, even after the cognitive decline. Moreover, APP/PS1 present similar social interaction alterations to old C57 mice (&gt;18m). Further, the activation of electrically stimulated LH neurons by local IGF‐I in young mice was reduced in middle‐aged and aged mice. Middle‐age C57 mice injected with DSP‐4 mice and APP/PS1 present disrupted social behavior and LC activity.ConclusionConsequently, IGF‐I can activate and modulate LC responses with our results. Social and emotional disturbances may be related to IGF‐I resistance in LC, reflecting a broader loss of IGF‐I activity in the aged mouse brain.

SERUM COPEPTIN AS A PROGNOSTIC MARKER IN PRE-ECLAMPSIA

Objective: Pre-eclampsia (PE) is as a risk factor for subsequent cardiovascular and kidney disease. Serum copeptin correlates with adverse kidney outcomes in the general population and is increased during PE as compared to healthy pregnancy. We describe the association between copeptin and subsequent kidney outcomes in pregnant women. Design and method: We enrolled 372 patients with PE and 82 with healthy pregnancy in this prospective cohort study. Serum copeptin was measured at 6 weeks post-partum (PP). Office blood pressure (BP), eGFR and albuminuria were measured at 6 weeks as well as at 1 year PP in a sub-group of 110 patients. Interaction effect was tested using likelihood ratio test (LRT). Results: As compared to healthy controls, patients with PE were less frequently Caucasian, more likely smokers and had higher body mass index (p &lt; 0.05). At 6 weeks PP, copeptin levels were similar between groups. At one year PP, systolic BP (SBP), diastolic BP (DBP) and albuminuria were higher in PE as compared to control patients (p &lt; 0.05) while eGFR was similar between groups. A significant interaction existed between copeptin and PE status regarding DBP at 1 year PP (p = 0.045 for LRT). A similar but borderline interaction existed between copeptin and PE status for albuminuria at 1 year PP (p = 0.126 for LRT). Conclusions: At 6 weeks PP, women who suffered from PE do not have increased copeptin levels as compared to healthy controls. However, in case of PE only, copeptin levels are associated with subsequent adverse kidney outcome. Whether this association is causal and would represent a potential therapeutic target remains to be tested.

Triple Evolution: An Important Channel in the Formation of Type Ia Supernovae

Type Ia supernovae (SNe Ia) are thought to be the result of thermonuclear explosions in white dwarfs (WDs). Commonly considered formation pathways include two merging WDs (the double-degenerate channel) and a single WD accreting material from a H or He donor (the single-degenerate channel). Since the predicted SN Ia rates from WDs in binaries are thought to be insufficient to explain the observed SN Ia rate, it is important to study similar interactions in higher-order multiple-star systems such as triple systems. We use the evolutionary population synthesis code Multiple Stellar Evolution (MSE) to study the stellar evolution, binary interactions, and gravitational dynamics of the triple-star systems. Also, unlike previous studies, prescriptions are included to simultaneously take into account the single- and double-degenerate channels, and we consider triples across the entire parameter space (including those with tight inner binaries). We explore the impact of typically ignored or uncertain physics such as flybys and common envelope prescription parameters on our results. The majority of systems undergo circular mergers to explode as SNe Ia, while eccentric collisions contribute to 0.4%−4% of SN Ia events. The time-integrated SN Ia rate from the triple channel is found to be , which is, surprisingly, similar to that of the isolated binary channel, where the SN Ia rate is . This implies that triples, when considering their entire parameter space, yield an important contribution to the overall SN Ia rate.

Synchronizing the EMRIs and IMRIs in AGN Accretion Disks

Extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are important gravitational-wave (GW) sources for the Laser Interferometer Space Antenna (LISA). So far, their formation and evolution have been considered to be independent. However, recent theories suggest that stellar-mass black holes (sBHs) and intermediate-mass black hole (IMBHs) can coexist in the accretion disk of an active galactic nucleus (AGN), which indicates that EMRIs and IMRIs may form in the same place. Motivated by the fact that a gas giant migrating in a protoplanetary disk could trap planetesimals close to its orbit, in this paper we study a similar interaction between a gap-opening IMBH in an AGN disk and the sBHs surrounding it. We analyze the torques imposed on the sBHs by the disk and also by the IMBH, and show that the sBHs can be trapped by the IMBH if they are inside the orbit of the IMBH. We then implement the torques in our numerical simulations to study the migration of an outer IMBH and an inner sBH, which are both embedded in an AGN disk. We find that their migration is synchronized until they reach a distance of about 10 Schwarzschild radii from the central supermassive black hole, where the pair break up due to strong GW radiation. This result indicates that LISA may detect an EMRI and an IMRI within several years from the same AGN. This GW source will bring rich information about the formation and evolution of sBHs and IMBHs in AGNs.

Structural insights into the regulation of the human E2∼SUMO conjugate through analysis of its stable mimetic

Protein SUMOylation is a ubiquitylation-like post-translational modification (PTM) that is synthesized through an enzymatic cascade involving an E1 (SAE1:SAE2), an E2 (UBC9), and various E3 enzymes. In the final step of this process, the small ubiquitin-like modifier (SUMO) is transferred from the UBC9∼SUMO thioester onto a lysine residue of a protein substrate. This reaction can be accelerated by an E3 ligase. As the UBC9∼SUMO thioester is chemically unstable, a stable mimetic is desirable for structural studies of UBC9∼SUMO alone and in complex with a substrate and/or an E3 ligase. Recently, a strategy for generating a mimetic of the yeast E2∼SUMO thioester by mutating alanine 129 of Ubc9 to a lysine has been reported. Here, we reproduce and further investigate this approach using the human SUMOylation system and characterize the resulting mimetic of human UBC9∼SUMO1. We show that substituting lysine for alanine 129, but not for other active-site UBC9 residues, results in a UBC9 variant that is efficiently auto-SUMOylated. The auto-modification is dependent on cysteine 93 of UBC9, suggesting that it proceeds via this residue, through the same pathway as that for SUMOylation of substrates. The process is also partially dependent on aspartate 127 of UBC9 and accelerated by high pH, highlighting the importance of the substrate lysine protonation state for efficient SUMOylation. Finally, we present the crystal structure of the UBC9-SUMO1 molecule, which reveals the mimetic in an open conformation and its polymerization via the noncovalent SUMO-binding site on UBC9. Similar interactions could regulate UBC9∼SUMO in some cellular contexts.