Excess Contribution Research Articles

Surpassing the Standard Quantum Limit Using an Optical Spring.

Quantum mechanics places noise limits and sensitivity restrictions on physical measurements. The balance between unwanted backaction and the precision of optical measurements imposes a standard quantum limit (SQL) on interferometric systems. In order to realize a sensitivity below the SQL, it is necessary to leverage a backaction evading measurement technique, reduce thermal noise to below the level of backaction, and exploit cancellations of any excess noise contributions at the detector. Many proof of principle experiments have been performed, but only recently has an experiment achieved sensitivity below the SQL. In this work, we extend that initial demonstration and realize sub-SQL sensitivity nearly two times better than previous measurements, and with an architecture applicable to interferometric gravitational wave detectors. In fact, this technique is directly applicable to Advanced LIGO, which could observe similar effects with a detuned signal recycling cavity. We measure a total sensitivity below the SQL by 2.8dB, corresponding to a reduction in the noise power by 72±5.1% below the quantum limit. Through the use of a detuned cavity and the optical spring effect, this noise reduction is tunable, allowing us to choose the desired range of frequencies that fall below the SQL. This result demonstrates access to sensitivities well below the SQL at frequencies applicable to LIGO, with the potential to extend the reach of gravitational wave detectors further into the Universe.

Distinguishing Extreme Precipitation Mechanisms Associated with Atmospheric Rivers and Nonatmospheric Rivers in the Lower Yangtze River Basin

Abstract This study investigates the disparity in quantitative moisture contribution and synoptic-scale vertical motion in the lower reaches of the Yangtze River basin (LYRB) for different extreme precipitation (EP) types, which are categorized as EP associated with atmospheric river (AR&EP) or EP associated with nonatmospheric river (non-AR&EP). To analyze moisture contribution, backward tracking using the Water Accounting Model-2layers is performed. In general, the remote moisture contribution is 9.7 times greater than the local contribution, with the ocean contribution being 1.67 times stronger than the land contribution. However, terrestrial and oceanic contributions obviously increase in the EP types, especially for oceanic contribution being double in magnitude. Notably, the west Pacific (WP) contribution emerges as the dominant differentia between the EP types, playing a crucial role in the AR formation. By solving the quasigeostrophic omega equation, the upper-level jet (ULJ) stream acts as the primary dynamic forcing for transverse vertical motion in AR&EP, while the baroclinic trough exhibits a relatively weaker influence. However, both systems have a nearly equal impact on vertical velocity in non-AR&EP. The enhanced shearwise elevation in the non-AR&EP type is the response of the stronger upper-level ridge over the Tibetan Plateau (TP), which induces enhanced Q vector, the divergence pointing toward the LYRB. However, the main dynamic difference is the location of ULJ, which serves as the trigger role although weak. Diabatic forcing proves to be the decisive factor for vertical motion development, the difference attributed to the released excessive latent heating with excess moisture contribution from the WP in AR&EP with enhanced precipitation. Significance Statement The main objective of this study is to investigate quantitative moisture contribution by applying Water Accounting Model-2layers and vertical motion attribution using the quasigeostrophic omega equation for extreme precipitation types based on the presence or absence of atmospheric river. Our findings reveal excessive moisture from the west Pacific serving not only as key in atmospheric river formation but also as the primary trigger for intensified diabatic vertical motion, inducing enhanced precipitation. The direction of strong winds in the north of the Tibetan Plateau holds crucial forecasting implications, which determine the location of the upper-level jet stream downstream. The transverse vertical motion, induced by the upper-level jet stream, plays the dominant dynamic role in both extreme precipitation (EP) types.

Impact of proximity of hard and soft segment on IR frequency of carbamate links correlating the mechanical properties of surface-functionalized fly ash–reinforced polyurethane composites

Abstract Polyurethane composites synthesized by interaction of fly ash filler with polyether polyol, cross-linking agent, and curing agent in a certain ratio. The study’s findings show that the mechanical properties of polyurethane composite are lowered by the hydroxyl moieties of surface-functionalized fly ash that are chemically or physically linked. The study also reveals that prior subjecting the samples of surface-functionalized fly ash–reinforced polyurethane composite material for destructive analysis by UTM for evaluating mechanical properties. The in-depth study of the IR spectroscopy data of the composites is done focusing onto the stretching frequency of carbonyl group of carbamate links the trend in mechanical behavior of the samples, the number of fly ash–carbamate links, and proximity of HS–SS (hard segment–soft segment) of fly ash–reinforced polyurethane composites can be foretold. By a detailed analysis of the patterns of carbonyl stretching frequencies of carbamate links, one can gain insight into the microphasic level of the separation and proximity of hard and soft segments in composites, which govern their mechanical properties. The relationships between carbamate carbonyl stretching frequencies and mechanical characteristics of composites have been found to be inversely correlated. In order to offset the excess hydroxyl group contribution due to OH-loaded fly ash, as indicated by the isocyanate (NCO) peak intensity (2,240–2,280 cm−1) in the composite’s infrared spectra, the studies were conducted at a higher index ratio (1.64).

Reaction calorimetry and structural crystal properties of non-ideal binary rhabdophane solid solutions (Ce1−xREExPO4·nH2O)

Rhabdophane is a hydrous phosphate that commonly replaces monazite as a weathering product in critical mineral deposits during the alteration of rare earth elements (REE) bearing carbonatites and alkaline igneous complexes. It is an important host to the light (L)REE (i.e., La to Gd) but the stability and structure of binary solid solutions between the Ce and the other LREE endmembers have not yet been determined experimentally. Here we present room temperature calorimetric experiments that were used to measure the enthalpy of precipitation of rhabdophane (Ce1−xREExPO4·nH2O; REE = La, Pr, Nd, Sm, Eu, and Gd). The solids were characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and the role of water in the rhabdophane structure was further determined using thermogravimetric analysis coupled with differential scanning calorimetry. The calorimetric experiments indicate a non-ideal behavior for all of the binary solid solutions investigated with an excess enthalpy of mixing (ΔHex) described by a 2- to 3-term Guggenheim parameters equation. The solid solutions were categorized into three groups: 1) binary Ce-La and Ce-Pr which display positive ΔHex values with a slight asymmetry; 2) binary Ce-Nd and Ce-Sm which display negative ΔHex values with a nearly symmetric shape; 3) Ce-Eu and Ce-Gd which display both negative and positive ΔHex values with nearly symmetric shape. The excess Gibbs energy (ΔGex) of the solid solutions was further investigated using a thermodynamic analysis approach of aqueous-solid solution equilibria and the optimization programs GEMS and GEMSFITS. The resulting ΔGex values combined with the calorimetric ΔHex values indicate that there is likely an excess entropy contribution implying important short-range structural modifications in the solid solutions dependent on the deviation of the REE ionic radii from the size of Ce3+. These observations corroborate with the trends in the Raman v1 stretching bands of the PO4-site. The excess molar volumes determined from X-ray diffraction analysis further indicate an overall asymmetric behavior in all of the studied binary solid solutions, which becomes increasingly important from La to Gd. The pronounced short-range order–disorder occurring in groups 2 and 3 solid solutions mimics some of the behavior observed from previous studies in anhydrous monazite solid solutions. This study highlights the potential to use the chemistry and the structural modifications of rhabdophane as potential indicators of formation conditions in geologic systems and permits improving our modeling capabilities of REE partitioning in critical minerals systems.

Compositional behavior of heat capacity and magnetic properties in double spinel ferrites

The purpose of the work is to identify the effects of the substitution of paramagnetic ions in ferromagnetic ferrites by diamagnetic components of zinc and aluminum. The following isomorphic spinel series are the object of review: Me(1-x)ZnxFe2O4 (Me – Ni, Co, Li, Cu, Mg) and Li0.5Fe2.5-xAlxO4 (x= 0-2.5). The single-phased samples were synthesized by ceramic procedure. Heat capacity near standard temperature Cp (298.15) was studied using calorimeter methods: drop calorimeter and DSC. Magnetic parameters – magnetic moments (M) and Curie temperatures (Tc) - were determined. All Me-Zn ferrite systems are characterized by dome-shaped correlations between heat capacity Cp(298) and composition (x), which have maximum values in the equimolecular region (x=0.4-0.6). This fact coincides with the nature of the compositional dependence of magnetic moments and indicates a significant effect of the excess magnetic contribution on the total heat capacity. A noticeable influence of the cooperative Jahn-Teller effect and the associated tetragonal distortion of the cubic lattice of Cu-Zn ferrites with a low Zn content (x<0.2) is observed, which causes overestimated values of the heat capacity of these compositions. Curie temperatures reveal the rectilinear decrease with increasing diamagnetic Zn and Al content in ferrite systems. The results are presented by graphs and tables.

THz spectroscopy on the amino acids L-serine and L-cysteine.

We present a detailed study on the temperature-dependent THz spectra of the polycrystalline amino acids, L-serine and L-cysteine, for wavenumbers from 20 to 120cm-1 and temperatures from 4 to 300K. Even though the structure of these two amino acids is very similar, with a sulfur atom in the side chain of cysteine instead of an oxygen atom in serine, the excitation spectra are drastically different. Obviously, the vibrational dynamics strongly depend on the ability of cysteine to form sulfur-hydrogen bonds. In addition, cysteine undergoes an order-disorder type phase transition close to 80K, documented by additional specific heat experiments, with accompanying anomalies in the THz results. On increasing temperatures, well-defined vibrational excitations exhibit significant shifts in the eigenfrequencies with concomitant line-broadening yielding partly overlapping modes. Interestingly, several modes completely lose all their dipolar strength and are unobservable under ambient conditions. Comparing the recent results to the published work utilizing THz, Raman, and neutron-scattering techniques, as well as with abinitio simulations, we aim at a consistent analysis of the results ascribing certain eigenfrequencies to distinct collective lattice modes. We document that THz spectra can be used to fine-tune the parameters of model calculations and as fingerprint properties of certain amino acids. In addition, we analyzed the low-temperature heat capacity of both the compounds and detected strong excess contributions compared to the canonical Debye behavior of crystalline solids, indicating soft excitations and a strongly enhanced phonon-density of states at low frequencies.

Connecting polymer collapse and the onset of jamming.

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that the attractive systems quenched to temperatures below the glass transition T≪T_{g} and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e., the number of interparticle contacts N_{c} matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymer packings are hypostatic at jamming onset (i.e., with fewer contacts than degrees of freedom) but are effectively isostatic when including stabilizing quartic modes, which give rise to quartic scaling of the potential energy with displacements along these modes. While attractive disk and polymer packings are often considered hyperstatic with excess contacts over the isostatic number, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g., scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static packings generated via attractive collapse or compression of repulsive particles possess similar structural and mechanical properties.

Glass spectrum, excess wing phenomenon, and master curves in molecular glass formers: A multi-method approach.

The relaxation spectra of glass formers solely displaying an α-peak and excess wing contribution collected by various methods are reanalyzed to pin down their different spectral evolution. We show that master curve construction encompassing both α-peak and emerging excess wing works for depolarized light scattering (DLS) and nuclear magnetic resonance (NMR) relaxometry. It reveals the self-part of the slow dynamics' spectrum. Master curves are to be understood as a result of a more extensive scaling covering all temperatures instead of strict frequency-temperature superposition. DLS and NMR display identical relaxation spectra; yet, comparing different systems, we do not find a generic structural relaxation at variance with recent claims. Dielectric spectroscopy (DS) spectra show particularities, which render master curve construction obsolete. The DS α-peak is enhanced or suppressed with respect to that of DLS or NMR, yet, not correlated to the polarity of the liquid. Attempting to single out the excess wing from the overall spectrum discloses a stronger exponential temperature dependence of its amplitude compared to that below Tg and a link between its exponent and that of the fast dynamics' spectrum. Yet, such a decomposition of α-peak and excess wing appears to be unphysical. Among many different glasses, the amplitude of the excess wing power-law spectrum is found to be identical at Tg, interpreted as a relaxation analog to the Lindemann criterion.

Solvent stabilization of alkene epoxidation transition states within Ti-MFI: Interactions near and far from active sites

Kinetics of alkene epoxidation in Ti incorporated MFI (Ti-MFI) zeolites that contact liquid methanol (CH3OH) depend strongly on the bulk concentration of water ([H2O]) and the density of silanol groups ((SiOH)x) within the framework, because these species influence excess free energy contributions (Gε) that stabilize transition states for epoxidation and hydrogen peroxide derived reactive intermediates. These effects rely on hydrogen bonds among intrapore molecules that couple catalytic events to the structure of the surrounding solvent molecules. Turnover rates for 1-hexene (C6H12) epoxidation with hydrogen peroxide over Ti-MFI zeolites increase by ten-fold both when either [H2O] or (SiOH)x densities increase. Activation enthalpies and entropies of hydrophilic and hydrophobic Ti-MFI materials are similar at the lowest [H2O] (0.005 M H2O), implying solvation environments near active sites do not depend on defect density in the near-absence of H2O. However, kinetic barriers for these same Ti-MFI materials increase and diverge from one another as non-monotonic functions of [H2O] (0.005–5 M H2O), and these differences reflect stabilizing contributions from discrete solvation shells both adjacent (near) and further (or far) from active sites. The structure of these solvation shells must reorganize to accommodate H2O2 activation and formation of epoxidation transition states. Adsorption enthalpies for the epoxide product become more exothermic with larger values of [H2O] over each Ti-MFI catalyst, and the apparent activation enthalpies generally increase as epoxide adsorption enthalpies become more exothermic. Comparisons to trends previously obtained for Ti-BEA catalysts suggest the negative correlation indicates that excess contributions (Hε, Gε) impact reactive species (Ti-OOH) within the 10-membered ring pores of MFI to a greater extent than 12-membered ring pores due to distinctions among hydrogen bonding interactions among bound reactive species, spectating solvent molecules, and extended surfaces of MFI pores.

Nutritional Genomics and Cancer Prevention.

The scientific innovations have emphasized the importance of diet for one's health and wellbeing. The genetic revolution has enhanced our understanding about the effect of nutrients on genomic and transcriptomic profiles and gene-nutrition interactions (nutritional genomics). Furthermore, the contribution of micronutrient insufficiencies and macronutrient excess is evident in the development and progression of many diseases, especially cancer. It is speculated that nutrients have capacity to implicitly affect the physiological and pathophysiological processes via gene expression various regulatory processes. Moreover, the nutrients are known to affect the cellular networks involved in cancer progression and cancer inhibitory mechanisms targeting apoptosis or impaired angiogenesis. The interplay of regulatory processes in physiological systems and nutrients provides basis for the nutrigenomics. The functional genomics data further argue that cellular and molecular processes involved in the cancer progression are possibly programed genes during early development which may persist into adulthood and become detrimental. The incorporation of the functional interactions between nutrients and the genome has revolutionized the field of personalized medicine and provided the foundation for targeted cancer therapy through nutrients. There is growing evidence on the beneficial impacts of eating habits on lowering the risk of cancer, even if it can be difficult to pinpoint the precise role of nutrients. The nutrigenomic information may provide bases to develop disease prevention and treatment via nutrition, at the molecular level.

Underlying features for the enhanced electrostatic strength of the extremophilic malate dehydrogenase interface salt-bridge compared to the mesophilic one

Malate dehydrogenase (MDH) exists in multimeric form in normal and extreme solvent conditions where residues of the interface are involved in specific interactions. The interface salt-bridge (ISB) and its microenvironment (ME) residues may have a crucial role in the stability and specificity of the interface. To gain insight into this, we have analyzed 218 ISBs from 42 interfaces of 15 crystal structures along with their sequences. Comparative analyses demonstrate that the ISB strength is ∼30 times greater in extremophilic cases than that of the normal one. To this end, the interface residue propensity, ISB design and pair selection, and ME-residue’s types, i.e., type-I and type-II, are seen to be intrinsically involved. Although Type-I is a common type, Type-II appears to be extremophile-specific, where the net ME-residue count is much lower with an excessive net ME-energy contribution, which seems to be a novel interface compaction strategy. Furthermore, the interface strength can be enhanced by selecting the desired mutant from the net-energy profile of all possible mutations of an unfavorable ME-residue. The study that applies to other similar systems finds applications in protein–protein interaction and protein engineering. Communicated by Ramaswamy H. Sarma

ALE meta-analyses of voxel-based morphometry studies: Parameter validation via large-scale simulations

Activation likelihood estimation (ALE) meta-analysis has been applied to structural neuroimaging data since long, but up to now, any systematic assessment of the algorithm's behavior, power and sensitivity has been based on simulations using functional neuroimaging databases as their foundation. Here, we aimed to determine whether the guidelines offered by previous evaluations can be generalized to ALE meta-analyses of voxel-based morphometry (VBM) studies. We ran 365000 distinct ALE analyses filled with simulated experiments, randomly sampling parameters from BrainMap's VBM experiment database. We then examined the algorithm's sensitivity, its susceptibility to spurious convergence, and its susceptibility to excessive contributions by individual experiments. In general, the performance of the ALE algorithm was highly comparable between imaging modalities, with the algorithm's sensitivity and specificity reaching similar levels with structural data as previously observed with functional data. Because of the lower number of foci reported and the higher number of participants usually included in structural experiments, individual studies had, on average, a higher impact towards significant clusters. To prevent significant clusters from being driven by single experiments, we recommend that researchers include at least 23 experiments in a VBM ALE dataset, instead of the previously recommended minimum of n = 17. While these recommendations do not constitute hard borders, running ALE analyses on smaller datasets would require special diligence in assessing and reporting the contributions of experiments to individual clusters.

ALMA ACA Detection of Submillimeter Emission Associated with the Western Hot Spot of the Radio Galaxy Pictor A

In order to investigate the far-infrared excess detected from the western hot spot of the radio galaxy Pictor A with the Herschel observatory, submillimeter photometry is performed with the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array at Band 8 with the reference frequency of 405 GHz. A submillimeter source is discovered at the radio peak of the hot spot. Because the 405 GHz flux density of the source, 80.7 ± 3.1 mJy, agrees with the extrapolation of the synchrotron radio spectrum, the far-infrared excess is suggested to exhibit no major contribution at the ACA band. In contrast, by subtracting the power-law spectrum tightly constrained by the radio and ACA data, the significance of the excess in the Herschel band is well confirmed. No diffuse submillimeter emission is detected within the ACA field of view, and thus, the excess is ascribed to the western hot spot itself. In comparison to the previous estimate based on the Herschel data, the relative contribution of the far-infrared excess is reduced by a factor of ∼1.5. The spectrum of the excess below the far-infrared band is determined to be harder than that of the diffusive shock acceleration. This strengthens the previous interpretation that the excess originates via the magnetic turbulence in the substructures within the hot spot. The ACA data are utilized to evaluate the magnetic field strength of the excess and of diffuse radio structure associated with the hot spot.

Solvent Mediated Interactions on Alkene Epoxidations in Ti-MFI: Effects of Solvent Identity and Silanol Density

Selective alkene oxidation rates within zeolite pores reflect differences in contributions from thermodynamic nonidealities introduced by noncovalent interactions at solid–liquid interfaces and spatial constraints enforced by the zeolite topology. Epoxidation turnover rates for 1-hexene in Ti-MFI zeolite differ by 1000-fold across 10 combinations of solvents, including alcohols and acetonitrile, over Ti-MFI with distinct silanol defect densities. Solvent mediated noncovalent interactions persist across an extended binding environment that influences the stability of epoxidation transition states. Apparent activation enthalpies (ΔHApp⧧) and entropies (ΔSApp⧧) span 80 kJ mol–1 and 200 J mol–1 K–1, respectively, with the most positive values for both appearing in methanol. Hydrophilic (i.e., (SiOH)x defect rich) Ti-MFI-OH catalysts in methanol give the greatest turnover rates because entropic gains associated with the disruption of hydrogen-bonded networks of intrapore methanol and water dominate activation free energies. In situ infrared spectra show that the adsorption of 1,2-epoxyhexane to Ti sites disturbs the equilibrium solvent structure within pores in ways that reflect the density of the hydrogen bond donor and acceptors near active sites. This interpretation agrees with measured enthalpies for adsorption of 1,2-epoxyhexane to Ti active sites within solvent filled pores that correlate with ΔHApp⧧ across solvent and catalyst combinations. The displacement of solvent molecules and the associated rupture and formation of hydrogen bonds among solvents, pore walls, and nearby reactive molecules during catalysis and adsorption events incur substantial excess contributions that govern the reaction rates and barriers. These realizations explain the particular success of alkene epoxidations in mixtures of H2O2 and methanol over hydrophilic forms of Ti-MFI in industrial processes (e.g., the hydrogen peroxide–propylene oxide process). These findings demonstrate the gains achieved by appropriately pairing organic solvents with microporous catalysts to manipulate the intrinsic kinetics of reactions and the thermodynamics of adsorption at solid–liquid interfaces.

Abstract A066: Molecular phenotyping in single cell RNA sequencing allows for identification of common populations across studies and platforms

Abstract Single cell RNA sequencing (scRNA seq) has become a prominent tool towards understanding models of prostate cancer. However, there are limited approaches geared towards collating these experiments into a unified framework for understanding discoveries across studies. In our lab, we have performed scRNA seq on multiple organoid models, across a spectrum of phenotypes including amphicrine, adenocarcinoma, and neuroendocrine disease, as well as performed lineage barcode tracing in a subset of these experiments as a means of identifying lineage transitions. Additionally, we have scRNA seq on a robust patient-derived xenograft (PDX) model of metastasis, consisting of experiments from primary and metastatic PDX models collected from multiple tissues including both intact and castrated backgrounds. Along with data generated by our lab, we accessed published scRNA seq studies from other labs which broadened the pool of experiments to include data from cell lines and multiple single cell analysis platforms. In order to perform computational molecular phenotyping of the scRNA seq experiments, we curated gene sets from the literature and applied principal components analysis (PCA) to them as our molecular phenotyping scoring approach which is widely used by previous studies. Because of the diverse background of the studies being incorporated into our molecular phenotyping, we used the bioconductor stack of single cell analysis tools to perform quality control and removal of batch effects. We observe that molecular phenotyping of samples across different backgrounds shows common populations typically associated with proliferation and stemness, and that unique populations present in each sample are usually more associated with terminal differentiation and senescence. In addition to identifying common and unique populations across samples and platforms, we also can assess individual genes on their importance in the molecular phenotyping approach. The use of PCA to generate our molecular phenotyping score allows the rotation matrix to be used as an additional metric when ranking genes for biological importance in concert with commonly used metrics such as variability and deviance. When combining the global metrics with the rotation matrix for each gene set, genes can be arranged in a network to determine key genes for molecular phenotyping, allowing for more concise gene sets that decrease the computational overhead for performing the molecular phenotyping. Overall, our work suggests that a unified framework of analysis can yield new insights into scRNA seq studies by identifying common populations present across sample backgrounds and different scRNA seq technologies. Additionally, genes can be arranged into networks based on biological significance derived from global statistical analysis as well as molecular phenotyping to identify more concise gene signatures, decreasing computational overhead and highlighting genes with excessive contribution to biological state. Citation Format: Brian Capaldo, Michael Beshiri, Juan Yin, Kathy Kelly. Molecular phenotyping in single cell RNA sequencing allows for identification of common populations across studies and platforms [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A066.

Generalized chemical model for plasmas with application to the ionization potential depression

On the basis of the generalized Poisson–Boltzmann equation derived from the Bogolyubov chain of equations for the equilibrium distribution functions in the pair correlation approximation, a general expression is proposed for the Helmholtz free energy of a system that contains any number of components and whose particles interact via arbitrary potentials. This opens up an extraordinary opportunity to simultaneously treat a whole range of physical effects including partial ionization, quantum effects of diffraction and electron degeneracy, short- and long-range interactions of charged particles with neutrals, finite size effects, etc. It is shown that all medium constituents are tied together in a single screening matrix, whose determinant and trace determine the excess contribution to the free energy. The approach developed is then applied to the problem of the ionization potential depression (IPD) leading to quite simple analytical expressions, which turn out to be useful for various practical purposes. In particular, for a single ionization from the neutral state the IPD is shown to significantly depend on the ionization degree such that it consists of the difference of charged and neutral contributions for a fully ionized plasma and turns non-zero for an almost neutral medium. On the other hand, for a multiple ionization process finite size effects of atoms and ions are demonstrated to be of great importance and accounted for in order to achieve good agreement with experimental data on the IPD under warm dense matter conditions.

Graphical methods comparing living and dead assemblages, exemplified with benthic foraminifera from the Aveiro Lagoon, Portugal

This work introduces graphical methods documenting density, diversity (species richness combined with heterogeneity) and similarity in combined diagrams for estimating the influence of environmental and taphonomic factors in living (LAs) and dead (DAs) assemblages. In this paper, the diagrams compare: 1) densities per 1 g of sediment expressed in cubic squares; 2) diversities based on rarefaction species richness (x-axis) and Shannon H rarefaction (y-axis), both extended to infinity by the logistic Hull equation, and 3) similarity diagrams based on cosine measures (x-axis) and Spearman correlation coefficients (y-axis). Diagrams were exemplified for LAs and DAs found at 53 stations along channels and intertidal areas of the Aveiro Lagoon (Portugal). Eight ‘routes’ characterized by different trends in the distribution of the analyzed biotic parameters were recognized in six regions of the Aveiro Lagoon: ‘port area’, ‘central lagoon’, ‘northeast lagoon’, ‘northern and southern extremities of the lagoon’ and ‘city area’. In addition, Detrended Correspondence Analyses (DCA) based on diversity diagrams were performed to show the influence of environmental parameters, especially grain size, salinity, and pH, on the average species composition in each route. The comparative diagrams allow deduction about the impact of parameters that simultaneously affect LAs and DAs, such as hydrodynamics, post-mortem tests dissolution, physicochemical parameters, excessive contribution of organic matter, oxygen depletion, and pollution by metals. Based on these diagrams, the most favorable environments due to the most remarkable development and diversity of LAs and DAs are located in protected coves of the Aveiro Lagoon mouth.

A Nonrepeating Fast Radio Burst in a Dwarf Host Galaxy

We present the discovery of an as yet nonrepeating fast radio burst (FRB), FRB 20210117A, with the Australian Square Kilometre Array Pathfinder (ASKAP), as a part of the Commensal Real-time ASKAP Fast Transients Survey. The subarcsecond localization of the burst led to the identification of its host galaxy at z = 0.214(1). This redshift is much lower than what would be expected for a source dispersion measure (DM) of 729 pc cm−3, given typical contributions from the intergalactic medium and the host galaxy. Optical observations reveal the host to be a dwarf galaxy with little ongoing star formation—very different to the dwarf host galaxies of the known repeating FRBs 20121102A and 20190520B. We find an excess DM contribution from the host and attribute it to the FRB’s local environment. We do not find any radio emission from the FRB site or host galaxy. The low magnetized environment and the lack of a persistent radio source indicate that the FRB source is older than those found in other dwarf host galaxies, establishing the diversity of FRB sources in dwarf galaxy environments. We find our observations to be fully consistent with the “hypernebula” model, where the FRB is powered by an accretion jet from a hyperaccreting black hole. Finally, our high time resolution analysis reveals burst characteristics similar to those seen in repeating FRBs. We encourage follow-up observations of FRB 20210117A to establish any repeating nature.

Structural, optical, XPS, and magnetic properties of Sn–O nanoparticles

Sn–O nanoparticles ranging in average particle sizes from 13 to 420 nm have been prepared by levitation-jet aerosol synthesis through condensation of tin vapor in a mixed flow of inert gases and air/oxygen. XRD established the presence of mixed-phase of Sn, SnO, and SnO2 components in the nanoparticles. During optical measurements, the redshift of bandgaps was discovered in nanoparticles with SnO2 content <80% and blue shift in nanoparticles with SnO2 content >80%. The results indicate that the nanoparticles exhibit room-temperature ferromagnetism. The maximum net saturation magnetization observed in the studied nanoparticles is ≈ 7 memu/g near a Sn/O molar ratio of ≈0.58. Moreover, an excess magnetic contribution, either as paramagnetic or as diamagnetic susceptibility, has been observed. Raman studies found the presence of small amounts of Sn3O4 or Sn2O3 phases in the nanoparticles. The presence of oxygen vacancies in the nanoparticles was established by XPS. Their density increase accompanies by the saturation magnetization enhancement. We propose that the presence of definite localized states, like interacting and non-interacting vacancies on the Sn/SnO and SnO/SnO2 interfaces, is responsible for the observed magnetic phenomena.

Structural and thermodynamic effects of hydration in Na-zeolite A (LTA) from low-temperature heat capacity

Zeolite A (Linde Type A; LTA) is an industrially important porous mineral that has recently been shown to exhibit framework flexibility upon changes in hydration level. To investigate the flexibility transition from a thermodynamic perspective, we have performed heat capacity measurements on sodium zeolite A at seven incremental hydration levels ranging from zero to equilibrium with ambient air. Excess low-frequency vibrations beyond the predictions of the Debye model are found in all samples, and the frequency of these vibrations increases as a function of hydration level. This suggests that an increase in hydration causes a decrease in at least one type of framework flexibility for sodium zeolite A. In addition, a subtle excess heat capacity contribution from 150 to 280 K is observed only for low and intermediate hydration levels, which may arise from a transformation tied to framework flexibility previously observed in zeolite A via gas absorption calorimetry. Values of the standard thermodynamic functions Cp,m°, Δ0TSm°, Δ0THm°, andΦm° are also reported.