Time Of Formation Research Articles

Factors Influencing the Protective Effect of Salivary Pellicle Against Dental Erosion: A Concise Review

Dental erosion is the irreversible loss of dental hard tissue caused by chemical processes without bacteria involvement. Dental erosion prevalence has increased due to extensive consumption of acidic foods and drinks or suffering from gastrointestinal diseases. Salivary pellicle acts as a physical barrier that impedes direct contact between the tooth surface and erosive acids. Furthermore, it is a selectively permeable membrane that controls the diffusion of erosive acids to the tooth surface. Therefore, salivary pellicle can protect the tooth surface from erosive demineralization. The protective effect of salivary pellicle depends on the intraoral location, tooth substrate, thickness, formation time, composition, the pH level of erosive acids, and exposure time. This concise review aimed to provide an overview on factors influencing the protective effect of salivary pellicle against dental erosion.

JOYS+ study of solid-state 12C / 13C isotope ratios in protostellar envelopes. Observations of CO and CO_2 ice with the James Webb Space Telescope

The carbon isotope ratio is a powerful tool for studying the evolution of stellar systems due to its sensitivity to the local chemical environment. Recent detections of CO isotopologs in disks and exoplanet atmospheres revealed a high variability in the isotope abundance, ponting towards significant fractionation in these systems. In order to fully understand the evolution of this quantity in stellar and planetary systems, however, it is crucial to trace the isotope abundance from stellar nurseries to the time of planet formation. During the protostellar stage, the multiple vibrational modes of CO_2 and CO ice, which peak in the near- and mid-infrared, provide a unique opportunity to examine the carbon isotope ratio in the solid state. With the current sensitivity and wide spectral coverage of the James Webb Space Telescope, the multiple weak and strong absorption features of CO_2 and CO have become accessible at a high signal-to-noise ratio in solar-mass systems. We aim to study the carbon isotope ratio during the protostellar stage by deriving column densities and ratios from the various absorption bands of CO_2 and CO ice, and by comparing our results with the ratios derived in other astronomical environments. We quantify the CO_2 CO_2 and the CO CO isotope ratios in 17 class 0/I low-mass protostars from the CO_2 nu_1 nu_2 and 2 nu_1 nu_2 combination modes (2.70 mu m and 2.77 mu m), the CO_2 nu_3 stretching mode (4.27 mu m), the CO_2 nu_3 stretching mode (4.39 mu m), the CO_2 nu_2 bending mode (15.2 mu m), the CO 1-0 stretching mode (4.67 mu m), and the CO 1-0 stretching mode (4.78 mu m) using the James Webb Space Telescope NIRSpec and MIRI observations. We also report a detection of the 2-0 overtone mode of CO at 2.35 mu m. The column densities and CO_2 CO_2 ratios derived from the various CO_2 vibrational modes agree within the reported uncertainties, and we find mean ratios of 85 pm 23, 76 pm 12, and 97 pm 17 for the 2.70 mu m band, the 4.27 mu m band, and the 15.2 mu m band, respectively. The main source of uncertainty on the derived values stems from the error on the band strengths; the observational errors are negligible in comparison. Variation of the CO_2 CO_2 ratio is observed from one source to the next, which indicates that the chemical conditions of their envelopes might be genuinely different. The CO CO ratios derived from the 4.67 mu m band are consistent, albeit elevated with respect to the CO_2 CO_2 ratios, and we find a mean ratio of 165 pm 52. These findings indicate that ices leave the prestellar stage with elevated carbon isotope ratios relative to the overall values found in the interstellar medium, and that fractionation becomes a significant factor during the later stages of star and planet formation.

Deciphering the Milky Way disc formation time encrypted in the bar chrono-kinematics

Abstract We present a novel method to constrain the formation time of the Milky Way disc using the chrono-kinematic signatures of the inner Galaxy. We construct an O-rich Mira variable sample from the Gaia Long-period Variable catalogue to study the kinematic behaviour of stars with different ages in the inner Galaxy. From the Auriga suite of cosmological zoom-in simulations, we find that the age of the oldest stellar population with imprints of the bar in density and kinematics matches the disc spin-up epoch. This is because stars born before the spin-up show insufficient rotation and are not kinematically cold enough to be efficiently trapped by the bar. We find that the bar kinematic signature disappears for Mira variables with a period shorter than 190 days. Using the period-age relation of Mira variables, we constrain the spin-up epoch of the Milky Way to be younger than ∼11 − 12 Gyr (redshift ∼3). We also discuss and compare our method and result to other evidence of the Milky Way spin-up epoch under the context of a realistic age uncertainty. Age uncertainty leads to an overestimation of the disc formation time when performing backward modelling. Our constrain of the spin-up epoch is independent from previous studies because it relies on the kinematics of the inner Galaxy instead of the solar vicinity.

Intensifying Cyclopentanone Synthesis from Furfural Using Supported Copper Catalysts.

This work addresses catalytic strategies to intensify the synthesis of cyclopentanone, a bio-based platform chemical and a potential SAF precursor, via Cu-catalyzed furfural hydrogenation in aqueous media. When performed in a single step, using either uniform or staged catalytic bed configuration, high temperature and hydrogen pressures (180 °C and 38 bar) are necessary for maximum CPO yields (37 and 49 %, respectively). Parallel furanic ring hydrogenation of furfural and polymerisation of intermediates, namely furfuryl alcohol (FFA), limit CPO yields. Employing a two step configuration with optimal catalyst bed can curb this limitation. First, the furanic ring hydrogenation can be suppressed by using milder conditions (i. e., 150 °C and 7 bar, and 14 seconds of residence time). Second, FFA hydrogenation using tandem catalysis, i. e., a mix of β-zeolite and Cu/ZrO2, at 180 °C, 38 bar and 0.6, allows sufficient time for CPO formation and minimises polymerisation of FFA, thereby resulting in 60 % CPO yield. Therefore, this work recommends a split strategy to produce CPO from furfural. Such modularity may aid in addressing flexible market needs.

Controls on regional sulphate distribution in shallow groundwater in the western Canadian Interior Plains

Sulphate (SO4), predominantly derived from sulphur (S)-bearing glacial sediments distributed widely across the Canadian Interior Plains, contributes to high groundwater salinity and can be detrimental to riparian and dry-land ecosystems, agricultural production, and water use. While previous researchers investigated SO4 distribution and dynamics in shallow groundwater at local scales (<1500 km2), we examine SO4 occurrence in groundwater at larger scales, and to depths of ∼150 m, considering variations in geology, glacial history, climate, and geochemical and hydrogeological settings in the Canadian province of Alberta. Sulphate concentrations in groundwater vary considerably, with 15 % of 139,130 samples above the 500 mg/L Canadian drinking water aesthetic objective. Analysis of δ34SSO4 and δ18OSO4 from 179 wells throughout Alberta shows SO4 is dominantly derived from oxidation of S-bearing material. At this large scale, marine shale bedrock subcrops, glacial ice flow directions, and climate control SO4 distribution. Groundwater contains less SO4 (<200 mg/L) in western Alberta compared to the east due to a lack of S-bearing bedrock, higher groundwater recharge rates, thinner glacial sediments, and increased groundwater circulation. Focusing on a region in south-central Alberta (Red Deer area), hydrogeological characteristics relating to SO4 formation, recharge, permeability, hydraulic gradient, and travel time are included in a principal component analysis to identify six groundwater groups at varying stages of evolution and SO4 concentrations depending on their hydrogeological setting. Low SO4 concentrations are associated with areas of high recharge, where SO4 has been leached from the sediments, or with more evolved bedrock groundwater where SO4 has been reduced or was recharged in pre-glacial times. High SO4 concentrations are found in areas of lower recharge and permeability, where flushing occurs more slowly. Combining the Red Deer area and province-wide analyses, we identify seven regions across Alberta with characteristic distribution and controls on SO4 occurrence in shallow groundwater.

Self-Trapped Excitons in 3R ZnIn2S4 with Broken Inversion Symmetry for High-Performance Photodetection.

Exploring novel materials with intrinsic self-trapped excitons (STEs) is crucial for advancing optoelectronic technologies. In this study, 2D 3R-phase ZnIn2S4, featuring broken inversion symmetry, is introduced to investigate intrinsic STEs. This material exhibits a broadband photoluminescence (PL) emission with a full width at half maximum of 164nm and a large Stokes shift of ≈0.6eV, which arises from the distortion of [ZnS4]6- tetrahedral unit induced by the symmetry breaking and strong electron-phonon coupling. The photophysical properties of the STEs exhibit a high Huang-Rhys factor (15.0), rapid STEs formation time (166fs), and extended STEs lifetime (1039ps), as demonstrated by experimental evidence from temperature-dependent PL, Raman spectroscopy, and ultrafast absorption spectroscopy. Additionally, STE-induced photoconductiveeffect is elucidated, indicating that intrinsic STEs in 3R-ZnIn2S4 can provide a synergistic effect that enhances absorption capacity, localization, and lifetime by capturing the self-trapped hole state. Consequently, the 2D 3R-ZnIn2S4 photodetector exhibits remarkable broad-spectrum photosensitivity, including a photo-switching ratio of 11286, response times of less than 0.6ms, responsivity of 15.2AW-1, detectivity of 1.02×10¹¹ Jones, and external quantum efficiency of 5032% under 375nm light. These findings provide new ideas for exploring materials with intrinsic STEs to achieve novel high-performance photodetector applications.

The structure of humates in aqueous solutions and their biological activity

When studying humate solutions, it is often not taken into account that humic substances (HS) can form supramolecular formations (SMFs) from molecular particles. These SMFs are highly stable, that is, the particles-molecules of HS do not separate from them spontaneously. It follows that at concentrations of the existence of SMFs, it is they, and not the particles-molecules of HS, that should be in solutions and determine their properties. The purpose of the study is to assess the influence of the form of existence of HS in solutions on their physico-chemical properties and biological activity. Solutions of sodium humate from brown coal were used in the work. The experimental results showed that with an increase in the concentration of humates, an abrupt increase in pH in the range of 30–50 mg l⁻¹ is observed. These concentrations correspond to the literature data on changes in the structure of HC in solutions: at concentrations above 30 mg l⁻¹ – barrier concentration – HS molecules form SMFs by self-assembly. Both molecular particles and SMFs, due to the diphilicity of HS, have the properties of surfactants. That is, in solutions at the interface of the “water–air” phases, HS films form. The strength of the films depends on the size of its constituent particles and the speed of their movement from the thickness to the surface of the solution. When plotting graphs in the coordinates “Film formation time in hours–Log humate concentration, mg l⁻¹”, a jump corresponding to the barrier concentration was detected on the curves. It was also found that during foliar treatment of cucumber shoots with mechanoactivated humate solutions with concentrations below the barrier, the stimulation effect increases, apparently due to the transition from the existence of HS in solution in the form of SMFs to existence in the form of particles-molecules that, due to their small size, can penetrate plant cells.

Identification of candidate martian maars in Arena Colles and Nephentes/Amenthes with extension to maars as a proxy for past ground water/ice depths

Maar craters represent the top of a volcanic construct produced by subsurface explosive interactions between ground water/ice and rising magma. Recent comprehensive studies of terrestrial maars have established the commonality of complex maar crater geometries composed of overlapping circular components with a single near continuous outer rim. These distinctive geometries, and the availability of high spatial resolution visible imagery on Mars, provide an opportunity to identify and evaluate candidate maars on Mars. This study evaluated 49 closed depressions in Arena Colles and Nephentes/Amenthes based on their proximity to pitted cones of proposed volcanic origin. Across the two regions, 13 candidate maars were recognized for their similarity to terrestrial maars in absence of any exclusionary characteristics related to other formation processes such as butterfly ejecta around binary craters. The recognition of maars on Mars would provide additional proxies for the presence and range of depths for ground water and ice at the time of eruption. The diameter of the multiple overlapping circular components in maar craters can be used to provide first order estimates of the depths of the underlying diatreme as a proxy for depth of explosions and thus presence of water in the subsurface. Estimates based on the circular components of the 13 candidate maars recognized here indicate that water/ice depths at the time of formation would be between 0.6 and 4 km.

Hf–W isotope systematics of bulk chondrites: Implications for early Solar System evolution

The short-lived 182Hf–182W system is widely used for constraining the chronology of the early Solar System, including the timing of the formation, thermal evolution, and differentiation of planetary bodies. Utilizing the full potential of the Hf–W system requires knowledge of the Hf/W ratio and W isotopic composition of primitive chondritic material. However, metal-silicate heterogeneity among chondritic samples can complicate accurately determining the Hf–W systematics of bulk chondrite parent bodies. Moreover, interpreting Hf–W data for chondrites may be complicated by potential nucleosynthetic W isotope anomalies. To this end, we report Hf/W ratios and W isotope compositions for bulk ordinary and enstatite chondrites, as well as the first such data for Rumuruti chondrites. We find that ordinary and Rumuruti chondrites show no resolvable nucleosynthetic anomalies, whereas resolved ε183W (i.e., 0.01 % deviation in 183W/184W from terrestrial standard) excesses in individual enstatite chondrites suggest the presence of nucleosynthetic W isotope anomalies in bulk meteorite samples originating in the inner Solar System. These anomalies necessitate corrections when accurately quantifying radiogenic 182W variations. Furthermore, several ordinary chondrites deviate in Hf/W ratios and W composition from the parent body compositions previously obtained from internal 182Hf–182W isochrons, indicating variations in the abundance of metal across different chondrite samples. Similarly, the Hf–W systematics of some enstatite chondrites also deviate from the parent body values, which can be attributed to the heterogeneous distribution of Hf carrier phases. The new observations highlight the challenges in obtaining Hf-W data that are representative of the chondrite parent bodies from individual chondrites, especially from metal-rich samples. By contrast, Rumuruti chondrites of variable petrologic types exhibit uniform Hf/W and 182W/184W ratios, suggesting that these samples are representative of their parent body. Whereas their Hf/W ratio is similar to that of carbonaceous chondrites, their W isotope composition is less radiogenic. This indicates that the Rumuruti precursor reservoir most likely had a significantly lower Hf/W ratio than the ratio measured in Rumuruti chondrites today. These findings underscore the importance of understanding the likely variations in Hf-W isotope systematics of iron meteorite parent bodies for accurately determining the timing of core formation.

The impact of non-isothermal adsorption of dissolved gas on drying of acoustically levitated slurry droplet

In this study, we developed a transient convective heat and mass transfer model of an acoustically levitated slurry droplet evaporating in an atmosphere of air, water vapor, and soluble gas. The advanced model considers the effects of acoustic streaming, forced convection, non-isothermal gas absorption, and adsorption of dissolved gas on the evaporation rate of a liquid droplet containing small active solid particles. Adsorption of dissolved in a droplet soluble gas by solid particles leads to decreased dissolved gas concentration in a liquid droplet. A reduction in dissolved gas concentration in a liquid droplet causes an increase in the mass flux of active soluble gas from a gaseous phase to a slurry droplet, which causes a rise in the heating effect of absorption and an increase in evaporation rate of a droplet. The heat effect of adsorption also intensifies the evaporation rate. It is shown that the time of porous shell formation is essentially shorter when solid particles in slurry droplets are active compared to inert particles.

Low [O/Fe] Ratio in a Luminous Galaxy at the Early Cosmic Epoch (z &gt; 10): Signature of Short Delay Time or Bright Hypernovae/Pair-instability Supernovae?

Abstract We present an [O/Fe] ratio of a luminous galaxy GN-z11 at z = 10.60 derived with the deep public JWST/NIRSpec data. We fit the medium-resolution grating (G140M, G235M, and G395M) data with the model spectra consisting of BPASS-stellar and Cloudy-nebular spectra in the rest-frame UV wavelength ranges with Fe absorption lines, carefully masking the other emission and absorption lines in the same manner as previous studies conducted for lower-redshift (z ∼ 2–6) galaxies with oxygen abundance measurements. We obtain an Fe-rich abundance ratio [ O / Fe ] = − 0.37 − 0.22 + 0.43 , which is confirmed with the independent deep prism data as well as by the classic 1978 index method. This [O/Fe] measurement is lower than that measured for star-forming galaxies at z ∼ 2–3. Because z = 10.60 is an early epoch after the Big Bang (∼430 Myr) and the first star formation (likely ∼200 Myr), it is difficult to produce Fe by Type Ia supernovae (SNe Ia), which requires sufficient delay time for white-dwarf formation and gas accretion. The Fe-rich abundance ratio in GN-z11 suggests that the delay time is short or that the major Fe enrichment is not accomplished by SNe Ia but by bright hypernovae (BrHNe) and/or pair-instability supernovae (PISNe), where the yield models of BrHNe and PISNe explain Fe, Ne, and O abundance ratios of GN-z11. The [O/Fe] measurement is not too low to rule out the connection between GN-z11 and globular clusters (GCs) previously suggested by the nitrogen abundance but rather supports the connection with a GC population at high [N/O] if a metal dilution process exists.

Forecasting the Population of Globular Cluster Streams in Milky Way–type Galaxies

Thin stellar streams originating from globular clusters (GCs) are among the most sensitive tracers of low-mass dark matter subhalos. Joint analysis of the entire population of stellar streams will place the most robust constraints on the dark matter subhalo mass function, and therefore the nature of dark matter. Here we use a hierarchical model of GC formation to forecast the total number, masses, and radial distribution of dissolved GC in Milky Way–like galaxies. Furthermore, we generate mock stellar streams from these progenitors’ orbital histories taking into account the clusters’ formation and accretion times, mass, and metallicity. Out of ∼10,000 clusters more massive than 104 M ⊙, ∼9000 dissolved in the central bulge and are fully phase mixed at the present, while the remaining ∼1000 survive as coherent stellar streams. This suggests that the current census of ∼80 GC streams in the Milky Way is severely incomplete. Beyond 15 kpc from the Galactic center we are missing ∼100 streams, of which the vast majority are from accreted GCs. Deep Rubin photometry (g ≲ 27.5) would be able to detect these streams, even the most distant ones beyond >75 kpc. We also find that M31 will have an abundance of streams at galactocentric radii of 30–100 kpc. We conclude that future surveys will find a multitude of stellar streams from GCs, which can be used for dark matter subhalo searches.

Development of detachment fault system associated with a mature metamorphic core complex: Insight from the Kaiping Sag, northern South China Sea rifted margin

AbstractDetachment fault system associated with a mature metamorphic core complex (MCC) is still not well understood. Using high‐resolution 3D seismic data, we analyse the geometries and kinematic development of detachment fault system associated with a mature and exhumated MCC in the northern South China Sea rifted margin, with an emphasis on the MCC‐associated faults within the supra‐detachment basin. Faults within the supra‐detachment basin can be classified into three stages, the pre‐MCC, syn‐MCC and post‐MCC faults, based on their formation time relative to the MCC. The NE to NEE‐striking pre‐MCC faults developed in the early syn‐rift 1 stage, and the NW to WNW‐striking post‐MCC faults were both dominated by the regional tectonics and are perpendicular to the extension directions. While the syn‐MCC faults, synchronous with the MCC development in the late syn‐rift 1 stage, show overall EW‐striking, consistent with the long axis of the KP MCC. These syn‐MCC faults were well developed and are significant in shaping the basin architecture. Besides, the syn‐MCC faults are regularly distributed in the four zones overlying the convex‐upward master detachment fault surface, and are defined in this study as a synthetic fault zone, an upper collapse synformal‐graben fault zone, a lower collapse antiformal‐graben fault zone and an antithetic fault zone respectively. These four fault zones show distinct features and evolutionary patterns, and have a closed relationship with the rolling‐hinge process of the KP MCC. An evolutionary model is established for the development of MCC‐associated detachment fault system which should have global implications.

Point-of-care viscoelastic coagulation monitoring device shows promise for informing resuscitation strategies in a canine hemorrhagic shock model.

To use a point-of-care viscoelastic coagulation monitoring device (VCM-Vet; Entegrion) and traditional tests to assess hemostatic changes during hemorrhagic shock in dogs. 8 healthy, purpose-bred Beagles were enrolled in a hemorrhagic shock model conducted from September through December 2021. Dogs were anesthetized, had baseline hemostatic variables measured after blood pressure was stabilized at 70 to 80 mm Hg for 10 minutes (T1), had blood withdrawn from a jugular vein to achieve a mean blood pressure of 40 ± 5 mm Hg for 10 minutes (T2), were resuscitated with 100% shed blood, and then had hemostatic variables evaluated 10 minutes later (T3). At each time point, hemostatic variables were measured with traditional tests (Hct, WBC count, platelet count, mean platelet volume, prothrombin time, activated partial thromboplastin time [aPTT], and concentrations of fibrinogen, antithrombin, and D-dimer) and the VCM-Vet device (clot time, clot formation time, α-angle, maximum clot formation, amplitude at 10 minutes [A10], amplitude at 20 minutes [A20], clot lysis index at 30 minutes [LI30], and clot lysis index at 45 minutes [LI45]). All dogs survived without complication. At T2 and T3 (vs T1), samples had significantly higher coagulability (increased median α-angle, A10, and A20) and fibrinolysis (decreased median LI30 and LI45) and significantly longer aPTT; however, all values remained within reference limits. The use of VCM-Vet helped identify complex hemostatic disturbances in dogs with hemorrhagic shock. The use of VCM-Vet shows promise in aiding veterinarians in optimizing resuscitation strategies based on real-time clotting data.

Detecting Detached Black Hole Binaries through Photometric Variability

Understanding the connection between the properties of black holes (BHs) and their progenitors is interesting in many branches of astrophysics. Discovering BHs in detached orbits with luminous companions (LCs) promises to help establish this connection since the LC and BH progenitor are expected to have the same metallicity and formation time. We explore the possibility of detecting BH–LC binaries in detached orbits using photometric variations of the LC flux, induced by tidal ellipsoidal variation, relativistic beaming, and self-lensing. We create realistic present-day populations of detached BH–LC binaries in the Milky Way (MW) using binary population synthesis where we adopt observationally motivated initial stellar and binary properties, star formation history, and the present-day distribution of these sources in the MW based on detailed cosmological simulations. We test detectability of these sources via photometric variability by Gaia and TESS missions by incorporating their respective detailed detection biases as well as interstellar extinction. We find that Gaia is expected to resolve ∼300–1000 (∼700–1500) detached BH–LC binaries with signal-to-noise ratio (SNR) ≥ 10 (1) depending on the photometric precision and details of supernova physics. Similarly, the number of resolved BH–LC binaries with TESS is ∼50–200 (∼140–350). We find that 136−15+15 BH–LC binaries would be common between Gaia and TESS. Moreover, ∼60–70 (∼50–200) BH–LC binaries identifiable using photometry with SNR ≥ 10 may also be resolved using Gaia’s radial velocity (astrometry).

On the effect of two-direction seasonal flows on barchans and the origin of occluded dunes

We inquire into the morphodynamics of barchans under seasonal flows. For that, we carried out grain-scale numerical computations of a subaqueous barchan exposed to two-directional flows, and we varied the angle and frequency of oscillations. We show that when the frequency is lower than the inverse of the characteristic time for barchan formation, the dune adapts to the new flow direction and recovers the barchan shape while losing less grains than under one-directional flow. For higher frequencies, the dune has not enough time for adaptation and becomes more round while losing more grains. For both cases, we show, for the first time, the typical dynamics of grains (trajectories and forces). In particular, the round barchans are similar to the so-called occluded dunes observed on Mars, where seasons have very high frequencies compared to the dune timescale, different from Earth. Our results represent a possible explanation for that shape.

Characterizing southeast Greenland fjord surface ice and freshwater flux to support biological applications

Abstract. Southeast Greenland (SEG) is characterized by complex morphology and environmental processes that create dynamic habitats for top marine predators. Active glaciers producing solid-ice discharge, freshwater flux, offshore sea ice transport, and seasonal landfast-ice formation all contribute to a variable, transient environment within SEG fjord systems. Here, we investigate a selection of physical processes in SEG to provide a regional characterization that reveals physical system processes and supports biological research. SEG fjords exhibit high fjord-to-fjord variability regarding bathymetry, size, shape, and glacial setting, influencing some processes more than others. For example, during fall, the timing of offshore sea ice formation near SEG fjords progresses temporally when moving southward across latitudes, while the timing of offshore sea ice disappearance is less dependent on latitude. The rates of annual freshwater flux into fjords, however, are highly variable across SEG, with annual average input values ranging from ∼ 1 × 108 to ∼ 1.25 × 1010 m3 (∼ 0.1–12.5 Gt) for individual fjords. Similarly, the rates of solid-ice discharge in SEG fjords vary widely – partly due to the irregular distribution of active glaciers across the study area (60–70° N). Landfast sea ice, assessed for eight focus fjords, is seasonal and has a spatial distribution highly dependent on individual fjord topography. Conversely, glacial ice is deposited into fjord systems year-round, with the spatial distribution of glacier-derived ice depending on the location of glacier termini. As climate change continues to affect SEG, the evolution of these metrics will vary individually in their response, and next steps should include moving from characterization to system projection. Due to the projected regional ice sheet persistence that will continue to feed glacial ice into fjords, it is possible that SEG could remain a long-term refugium for polar bears and other ice-dependent species on a centennial to millennial scale, demonstrating a need for continued research into the SEG physical environment.

Lipopolysaccharide from Proteus mirabilis Slows Platelet Plug Formation in Human Whole Blood

Platelets are well known for their role in hemostasis. Additionally, platelets play a crucial role in immune and inflammatory responses. Toll-like receptors (TLRs) can mediate bacterial interactions during infection, triggering platelets to initiate an inflammatory response. TLR-4 receptors enable direct interactions between platelets and the bacterial lipopolysaccharide (LPS) endotoxin. The aim of this study was to assess platelet plug formation in response to LPS from Proteus mirabilis. Human whole blood was treated with varying concentrations of LPS over a range of incubation times. Then, platelet plug formation time was measured, under high shear conditions using the platelet function analyzer PFA-100, as aperture closure time (CT). The addition of either 2 or 10 µg/mL of LPS to 80% whole blood significantly prolonged the CTs even in the absence of preincubation (p = 0.028 or p = 0.049, respectively). With added preincubation of LPS with whole blood, the measured CTs were further prolonged. If the preincubation time was set to 35 min, then even the addition of 0.2 µg/mL of LPS resulted in significant CT prolongation (p &lt; 0.001). Taken together, the platelet plug formation in the presence of collagen/ADP is significantly prolonged by the presence of LPS in a concentration and preincubation time-dependent manner. Exposure to P. mirabilis LPS reduces the platelet aggregation response in human whole blood.

Relationship between lipoprotein(a) and endogenous fibrinolytic status in patients with STEMI

Abstract Background The risk of myocardial infarction is at least doubled in individuals with lipoprotein(a) (Lp[a]) levels &amp;gt;90th percentile.[1] Lp(a) may exert pro-thrombotic effects by impairing fibrinolysis. Lp(a) has a high degree of homology to plasminogen and can competitively inhibit tissue plasminogen activator (tPA)-mediated plasminogen activation and tPA-mediated clot lysis.[2] Furthermore, Lp(a) stimulates the activity of plasminogen activator inhibitor-1, the major inhibitor of the fibrinolytic system. In patients with ST-segment elevation myocardial infarction (STEMI), impaired endogenous fibrinolysis is a strong, independent risk factor for recurrent cardiovascular events,[3] but the drivers of this are not fully understood. Whether impaired endogenous fibrinolysis is related to increased Lp(a) levels in patients with STEMI, is not known. Purpose We aimed to assess the relationship between Lp(a) and endogenous fibrinolysis in patients with STEMI. Methods In a prospective, observational study, venous blood samples were drawn from patients presenting with STEMI immediately before revascularisation, after dual antiplatelet therapy but before heparin administration. Endogenous fibrinolysis was measured immediately in non-anticoagulated whole blood using the point-of-care Global Thrombosis Test, which measures the time for occlusive thrombus formation under high shear (occlusion time) and the time for spontaneous lysis of the thrombus (lysis time).[3] Assessment of Lp(a) levels, measured by particle enhanced immunoturbidimetric assay, was performed with paired plasma samples, standardized against the International Federation of Clinical Chemistry reference material SRM2B for nmol/L. Lp(a) &amp;gt;32 nmol/L is associated with increased risk of ischaemic heart disease. Results A total of 80 patients were included (age 64±14y, 25% females and 86% Caucasian). There was a positive correlation between Lp(a) level and lysis time (r = 0.330, P = 0.003) (Figure 1). Lysis time was significantly longer in patients with Lp(a) &amp;gt;32 nmol/L (2782 [1626-3683] vs. 1725 [1259-2955] s, P = 0.044). Using a cut-point of lysis time ≥2500 s previously associated with a significantly increased cardiovascular risk in patients with STEMI, we showed that Lp(a) was significantly higher in patients with lysis time ≥2500 s (40 (22-111) vs. 18 (7-73) nmol/L, P = 0.045). Table 1 shows the relationship between clinical characteristics and Lp(a) and lysis time. Lp(a) level was higher in non-Caucasian patients. There was no correlation between Lp(a) and occlusion time (r = 0.156, P = 0.168). Conclusion In patients with STEMI, longer endogenous fibrinolysis time is related to higher Lp(a) level. Raised Lp(a) levels may, in part, contribute to impaired endogenous fibrinolysis. Future studies are required to assess whether reduction in Lp(a) with novel therapies currently in phase 3 trials can favourably modulate fibrinolysis and improve clinical outcomes.Figure 1

Post-Flowering Photoperiod Sensitivity of Soybean in Pod-Setting Responses

The development of soybean (Glycine max) is regulated by the photoperiod, with genes related to photoperiod sensitivity primarily focused on the flowering time. However, their roles in post-flowering reproductive development and the mechanisms by which the photoperiod affects them are not yet determined. In this study, we found that pod formation is sensitive to the photoperiod. Long-day conditions tended to extend the time from flowering to pod formation, and the first wave of flowers tended to fall off. Additionally, the photoperiod affected the pistil morphology; under short-day conditions, the stigma had a curved hook-like structure that facilitated better interaction with the filaments when pollen was released, ultimately influencing the timing of pod formation. Photoperiod-insensitive mutants, lacking E1 family and Evening Complex (EC) genes, showed no difference in the pod formation time under long-day or short-day conditions. Hormone content analysis and transcriptome data analysis indicated that various hormones, reactive oxygen species (ROS) burst pathway signals, and the application of sucrose solution in vitro might influence floral organ abscission.