Temperature-induced Changes Research Articles

Effect of Cu doping on properties of PbMoO4 single crystals as materials for luminescence thermometry

ABSTRACT Innovative temperature measurements based on contactless luminescence thermometry require materials that exhibit a significant change of the luminescence parameters in set temperature range. PbMoO4 and PbMoO4 doped with copper ions single crystals with optically good quality are grown using low-thermal-gradient Czochralski technique. PbMoO4 and PbMoO4:Cu2+ samples reveal intense photoluminescence band in the green spectral region. Investigations of the temperature-induced changes in the luminescence of molybdates PbMoO4 and PbMoO4:Cu2+over the 77–300 K temperature range are summarised and demonstrated. Comparative studies of decay kinetics, emission and excitation spectra allowed assessing the prospects of PbMoO4 and PbMoO4:Cu2+ crystals as materials for luminescence thermometry. An impurity composition was studied in the grown crystals PbMoO4:Cu2+ by the EPR and the structural position of impurity copper ion was established.

Bandgap formation under temperature-induced quasi-periodicity in an acoustic duct with flexible walls

This paper is concerned with the acoustic bandgap formation in a duct with periodically flush-mounted flexible walls, subject to a stream-wise temperature variation. A numerical model, based on a piecewise treatment of the arbitrary temperature gradient, is proposed for the accurate prediction of sound propagation in a complex thermal environment. Effects of the system quasi-periodicity due to the temperature change on the bandgap formation, as well as possible mitigation measures through parameter tuning, are revealed. It is shown that, on the top of the resonance bandgap, Bragg reflection bandgap can still be created despite the system quasi-periodicity. In addition to an alteration to the bandgap central frequency due to the temperature-induced acoustic wavelength changes inside the duct, the bandwidths of the bandgaps are also adversely affected, especially when the temperature gradient is large. Numerical analyses show the possibility of tuning and customizing the bandgap formation through a proper selection of the lattice distance and the structural parameters. A combined tuning strategy would warrant a merging of the bandgaps, adjustment of their central frequencies as well as an enlargement of the bandwidth for a given temperature variation range through creating a favorable coupling between the Bragg reflections and the local resonances of the flexible walls.

Thermal Liability of Hyaloclastite in the Krafla Geothermal Reservoir, Iceland: The Impact of Phyllosilicates on Permeability and Rock Strength

Geothermal fields are prone to temperature fluctuations from natural hydrothermal activity, anthropogenic drilling practices, and magmatic intrusions. These fluctuations may elicit a response from the rocks in terms of their mineralogical, physical (i.e., porosity and permeability), and mechanical properties. Hyaloclastites are a highly variable volcaniclastic rock predominantly formed of glass clasts that are produced during nonexplosive quench-induced fragmentation, in both subaqueous and subglacial eruptive environments. They are common in high-latitude geothermal fields as both weak, highly permeable reservoir rocks and compacted impermeable cap rocks. Basaltic glass is altered through interactions with external water into a clay-dominated matrix, termed palagonite, which acts to cement the bulk rock. The abundant, hydrous phyllosilicate minerals within the palagonite can dehydrate at elevated temperatures, potentially resulting in thermal liability of the bulk rock. Using surficial samples collected from Krafla, northeast Iceland, and a range of petrographic, mineralogical, and mechanical analyses, we find that smectite dehydration occurs at temperatures commonly experienced within geothermal fields. Dehydration events at 130, 185, and 600°C result in progressive mass loss and contraction. This evolution results in a positive correlation between treatment temperature, porosity gain, and permeability increase. Gas permeability measured at 1 MPa confining pressure shows a 3-fold increase following thermal treatment at 600°C. Furthermore, strength measurements show that brittle failure is dependent on porosity and therefore the degree of thermal treatment. Following thermal treatment at 600°C, the indirect tensile strength, uniaxial compressive strength, and triaxial compressive strength (at 5 MPa confining pressure) decrease by up to 68% (1.1 MPa), 63% (7.3 MPa), and 25% (7.9 MPa), respectively. These results are compared with hyaloclastite taken from several depths within the Krafla reservoir, through which the palagonite transitions from smectite- to chlorite-dominated. We discuss how temperature-induced changes to the geomechanical properties of hyaloclastite may impact fluid flow in hydrothermal reservoirs and consider the potential implications for hyaloclastite-hosted intrusions. Ultimately, we show that phyllosilicate-bearing rocks are susceptible to temperature fluctuations in geothermal fields.

Thermally Induced Diffusion and Restructuring of Iron Triade (Fe, Co, Ni) Nanoparticles Passivated by Several Layers of Gold.

The temperature-induced structural changes of Fe–, Co–, and Ni–Au core–shell nanoparticles with diameters around 5 nm are studied via atomically resolved transmission electron microscopy. We observe structural transitions from local toward global energy minima induced by elevated temperatures. The experimental observations are accompanied by a computational modeling of all core–shell particles with either centralized or decentralized core positions. The embedded atom model is employed and further supported by density functional theory calculations. We provide a detailed comparison of vacancy formation energies obtained for all materials involved in order to explain the variations in the restructuring processes which we observe in temperature-programmed TEM studies of the particles.

Temperature-Induced Changes in Reperfused Stroke: Inflammatory and Thrombolytic Biomarkers.

Although hyperthermia is associated with poor outcomes in ischaemic stroke (IS), some studies indicate that high body temperature may benefit reperfusion therapies. We assessed the association of temperature with effective reperfusion (defined as a reduction of ≥8 points in the National Institute of Health Stroke Scale (NIHSS) within the first 24 h) and poor outcome (modified Rankin Scale (mRS) > 2) in 875 retrospectively-included IS patients. We also studied the influence of temperature on thrombolytic (cellular fibronectin (cFn); matrix metalloproteinase 9 (MMP-9)) and inflammatory biomarkers (tumour necrosis factor-alpha (TNF-α), interleukin 6 (IL-6)) and their relationship with effective reperfusion. Our results showed that a higher temperature at 24 but not 6 h after stroke was associated with failed reperfusion (OR: 0.373, p = 0.001), poor outcome (OR: 2.190, p = 0.005) and higher IL-6 levels (OR: 0.958, p < 0.0001). Temperature at 6 h was associated with higher MMP-9 levels (R = 0.697; p < 0.0001) and effective reperfusion, although this last association disappeared after adjusting for confounding factors (OR: 1.178, p = 0.166). Our results suggest that body temperature > 37.5 °C at 24 h, but not at 6 h after stroke, is correlated with reperfusion failure, poor clinical outcome, and infarct size. Mild hyperthermia (36.5–37.5 °C) in the first 6 h window might benefit drug reperfusion therapies by promoting clot lysis.

Thermally induced changes in metalloid leachability of cemented paste backfill that contains blast furnace slag

In this research, the effect of curing temperature on the Arsenic (As(III)) leachability of cemented paste backfill (CPB) that contains blast furnace slag (OPC/Slag-CPB) are studied. ASTM C 1308 leaching protocol is adopted to assess the leachability of OPC/Slag-CPB specimens cured at various temperatures (2 °C, 20 °C and 35 °C). Furthermore, various microstructural techniques are used to relate the temperature-induced changes in the microstructural properties of the OPC/Slag-CPBs to their leaching characteristics. The results show that leaching of arsenic from OPC/Slag-CPB is temperature dependent. Higher curing temperature leads to a decrease in the amount of arsenic released from the OPC/Slag-CPB. The As leachability-decreasing factors are: (i) faster cement hydration rate and pozzolanic reaction with higher curing temperatures, which increase the volume of As immobilizing phases (C-S-H, CH, ettringite) in the OPC/Slag-CPB; (ii) lower volume of connective pores (smaller connective pore surface area) with higher curing temperatures, which decreases the area of reaction sites, thereby reducing the mobility of arsenic. Leaching of As from OPC/Slag-CPBs is dominated by diffusion, irrespective of the curing temperature. Results also reveal that CPBs with ordinary Portland cement (OPC) leach significantly less than CPBs with OPC and Slag (50/50) for all curing temperatures. However, curing temperature has the opposite effect on the OPC/Slag-CPBs compared to OPC-CPBs. OPC is suggested as a binder in situations where the principal design parameter is immobilizing As(III) in CPB subjected to various thermal curing conditions. The results indicate that curing temperature is a critical variable to consider when assessing the ability of CPB structures to release arsenic into the underground environment.

Does global warming intensify cost of antipredator reaction? A case study of freshwater amphipods

Global warming is a worldwide phenomenon affecting the functioning of diverse ecosystems, including fresh waters. Temperature increase affects physiology and behaviour of ectotherms due to growing energetic demands necessary to sustain increased metabolic rate. Anti-predator responses may resemble temperature-induced changes in organisms, suggesting synergism between these factors. To check how temperature shapes physiological and behavioural responses of ectotherms to predation risk, we exposed amphipods: Dikerogammarus villosus and Gammarus jazdzewskii to fish kairomones at 10, 17 or 24 °C. Animals were placed in tanks where temperature was gradually adjusted to the desired test temperature and acclimated under such conditions for 3 subsequent days. Then they were exposed to the predator cue (the Eurasian perch kairomone) for 35 min to test their acute responses. We measured metabolic rate (as respiration), antioxidant defence (CAT: catalase activity, TAS: total antioxidant status), oxidative molecules (TOS: total oxidative status), oxidative damage (TBARS: thiobarbituric acid reactive substances) and behaviour (locomotor activity). Amphipods increased respiration with raising temperature and when exposed to predation risk (all temperatures). Only G. jazdzewskii exhibited increased TOS when exposed to 24 °C or to predation risk at all temperatures. Antioxidant defence increased with raising temperature (CAT, TAS) and decreased under predation risk (CAT). Cellular damage increased in G. jazdzewskii under predation risk at 10 and 24 °C, but raised temperature itself did not generate any damage. Amphipods reduced locomotor activity at 24 °C. Thus, at elevated temperatures, amphipods minimized their cellular damage at the cost of increased antioxidant defence and lower locomotor activity (potentially disadvantageous under higher energetic demands). Under predation risk, the performance of antioxidant systems was reduced, probably due to energy allocation into anti-predatory mechanisms, leading to increased cellular damage at suboptimum temperatures. Thus, negative consequences of elevated temperature for organisms may be amplified by changes in behaviour (compromising food acquisition) and non-consumptive predator effects.

Temperature-induced changes in the synthesis gas composition in a high-temperature H2O and CO2 co-electrolysis system

Solid oxide electrolysis cell (SOEC) is an attractive renewable technology capable of producing synthesis gas (H2+CO) from H2O and CO2. An SOEC consists of a solid oxide electrolyte and two ceramic or metal-ceramic electrodes. H2O and CO2 are electrolyzed at the cathode producing H2 and CO, releasing O2− ions, which travel through the electrolyte to the anode side and recombine to produce pure oxygen gas as the byproduct. In the present study, a La0.7Sr0.2Ni0.2Fe0.8O3 cathode was used to co-electrolyze H2O and CO2 at three different operating temperatures- 700 °C, 750 °C and 800 °C. Synthesis gas was produced at all three operating temperatures with 100 % Faradaic efficiency. The composition of the syngas, however, was found to be a function of the operating temperature. In general, the H2/CO ratio in the syngas decreased with increased temperature. This was partially due to CO2 electrolysis becoming more favorable compared to H2O electrolysis at higher temperatures.

Use of Raman spectroscopy and size-exclusion chromatography coupled with HDX-MS spectroscopy for studying conformational changes of small proteins in solution

Protein-based drugs are a relatively new paradigm in modern therapeutics. These large molecule drugs often have much higher specificity and selectivity compared to small molecules that have been used in therapeutics for centuries. However, there are many analytical challenges associated with drug discovery and development of these new modalities. One of these analytical challenges concerns fast and robust assessment of peptides or small protein conformational structures in solution. In this study, we report a novel analytical approach that is based on Raman spectroscopy (RS) and size exclusion chromatography-hydrogen-deuterium exchange-mass spectrometry (SEC-HDX-MS) for probing conformational structures of proteins in solution. Specifically, we demonstrate that RS and SEC-HDX-MS can be used to probe temperature-induced changes in ubiquitin and insulin. We also show that a combination of these techniques provides a more comprehensive analysis and comparison of peptide or small protein conformational structures than by any one technique. Our results demonstrate that RS and SEC-HDX-MS allow for elucidation of sequential transformations in α-helix and β-sheet content of these proteins. These findings suggest that the proposed approach can be used for a fast investigation of changes in protein or peptide secondary structures under different solution conditions.

Temperature-induced localized exciton dynamics in mixed lead–tin based CH3NH3Pb1−xSnxI3 perovskite materials

Of late, tremendous research efforts have been made to obtain Pb-free low-toxicity halide perovskites. In this regard, the Sn-based perovskite is the focus of attention because of its properties being similar to those of Pb. This paper explores the fundamentals of temperature-induced dynamics of localized excitons in mixed Pb–Sn based CH3NH3Pb1−xSnxI3 perovskite materials. A quantitative model using the Monte Carlo simulation of exciton hopping and relaxation is developed to compute the photoluminescence (PL) peak energy, in addition to the PL line-width over a temperature regime of 10 K–300 K. The temperature-induced changes in the bandgap expansion allow the quantitative fit of our calculation to the experimental results. We show that the PL peak energies in CH3NH3PbI3 and CH3NH3Pb1−xSnxI3 are blue shifted due to the fact that the excitons are localized with higher energy localized states with increasing temperatures. It has also been found that the amount of redshift in PL peak energy decreases with an increase in Sn contents while the full width at half maximum increases in increased Sn content perovskite materials. These results give a deep insight into the exciton dynamics in CH3NH3Pb1−xSnxI3, further aimed at efficient applications in optoelectronic devices.

Distributed Salinity Sensor With a Polyimide-Coated Photonic Crystal Fiber Based on Brillouin Dynamic Grating

The distributed measurement of salinity is experimentally demonstrated for the first time, to the best of our knowledge, by Brillouin dynamic grating (BDG) with a polyimide-coated (PI-coated) polarization-maintaining photonic crystal fiber as the active sensing component. The position-related salinity change can be measured by mapping the birefringence change through the BDG, where the salinity altering can induce swelling or shrinking actions of the PI coating through absorbing or releasing water. To reveal the systematic characterizations of the proposed sensor, four PI-coated sensors with different coating thicknesses of 5 μm, 8 μm, 15 μm and 20 μm were fabricated as demos, achieving salinity sensitivities of 30.1 MHz/(mol/L) for 5 μm, 75.4 MHz/(mol/L) for 8 μm, 119.2 MHz/(mol/L) for 15 μm, and 139.6 MHz/(mol/L) for 20 μm, respectively. The proposed sensor shows a linear and reproducible response to the salinity change. And its measurement uncertainty is less than 10 MHz, yielding a salinity accuracy of 0.072 mol/L. The temperature crosstalk can be compensated through measuring the temperature-induced Brillouin frequency shift changes using Brillouin optical time-domain analysis.

Investigation of NiO reduction dynamics and properties of NiO-Ti powders

Abstract A detailed study of the mechanochemical (MC) processing of NiO-Ti [NiO-Ti (x at.%) with x = 20, 35] powders was carried out using a high-energy ball milling technique to investigate the formation of a NiO-based nanocomposite as a function of the milling time. During milling, the reduction of NiO to Ni follows a gradual process with a reduction of 10% and a self-sustaining process with a maximum reduction of 94% for x = 20 and 35 powders, respectively. The types of NiO reduction and the formation of ferromagnetic (FM) Ni from NiO could be accounted for by the change in magnetization to maximum values of 2 emu/g and 24 emu/g for the gradual and self-sustaining reactions, respectively. The relative fractions of Ni and NiO phases play an important role in (i) the formation of FM nanocomposite, (ii) the enhancement of magnetic anisotropy caused by the coexistence of mixed magnetic phases, (iii) temperature-induced structural phase changes and (iv) the gradual decrease in the induced FM phase with the increase in milling time. The process of time-dependent MC reduction and the resulting structural, vibrational and magnetic behavior of the in situ FM nanocomposite were studied in detail. This process may reveal potential applications in metallurgy and ore reduction processes.

Plastic sexual ornaments: Assessing temperature effects on color metrics in a color-changing reptile.

Conspicuous coloration is an important subject in social communication and animal behavior, and it can provide valuable insight into the role of visual signals in social selection. However, animal coloration can be plastic and affected by abiotic factors such as temperature, making its quantification problematic. In such cases, careful consideration is required so that metric choices are consistent across environments and least sensitive to abiotic factors. A detailed assessment of plastic trait in response to environmental conditions could help identify more robust methods for quantifying color. Temperature affects sexual ornamentation of eastern fence lizards, Sceloporus undulatus, with ventral coloration shifting from green to blue hues as temperatures rise, making the calculation of saturation (color purity) difficult under conditions where temperatures vary. We aimed to characterize how abiotic factors influence phenotypic expression and to identify a metric for quantifying animal color that is either independent from temperature (ideally) or best conserves individual's ranks. We compared the rates of change in saturation across two temperature treatments using seven metrics: three that are based on fixed spectral ranges (with two of them designed by us specifically for this system) and three that track the expressed hue (with one of them designed by us to circumvent spurious results in unornamented individuals). We also applied a lizard visual sensitivity model to understand how temperature-induced color changes may be perceived by conspecifics. We show that the rate of change in saturation between two temperatures is inconsistent across individuals, increasing at a higher rate in individuals with higher baseline saturation at lower temperatures. In addition, the relative color rank of individuals in a population varies with the temperature standardized by the investigator, but more so for some metrics than others. While we were unable to completely eliminate the effect of temperature, current tools for quantifying color allowed us to use spectral data to estimate saturation in a variety of ways and to largely preserve saturation ranks of individuals across temperatures while avoiding erroneous color scores. We describe our approaches and suggest best-practices for quantifying and interpreting color, particularly in cases where color changes in response to environmental factors.

Curing temperature dependency of the release of arsenic from cemented paste backfill made with Portland cement

In this research, the effect of curing temperature on the metalloid (As) leachability of cemented paste backfill (CPB; a mix of tailings, cement and water) is studied. ASTM C 1308 leaching protocol is used to determine the leachability of CPB samples subjected to different curing temperatures (2, 20 and 35 °C). In addition, the effect of curing temperature on the microstructure of CPB is assessed to determine if the temperature dependence of the leaching characteristics of CPB is related to variations in the microstructure of the cement matrix. The microstructural techniques used include, powder x-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy techniques. The results obtained indicate that the curing temperature has a significant effect on the leachability of CPB. It is found that as curing temperature increased from 2 °C to 35 °C the performance of the CPB for arsenic immobilization decreased. The magnitude of this temperature-induced change in As-leachability of CPB depends on the curing temperature range (low (≤20 °C) or elevated (35 °C) temperatures). This curing temperature dependency of the leachability of CPB is attributable to the temperature-induced changes in the pore structure of CPB, formation/development of hydration products and pH in the CPBs during the curing process. The results also indicate that diffusion dominates as the leaching mechanism through the studied temperature range and is independent of curing temperature. However, curing temperature does control the availability for arsenic to leach. The new findings presented in this paper will contribute to design more environmental-friendly cemented paste backfill materials and structures, which is vital for sustainable mining.

GABRG2 Deletion Linked to Genetic Epilepsy with Febrile Seizures Plus Affects the Expression of GABAA Receptor Subunits and Other Genes at Different Temperatures

Mutations in γ-aminobutyric acid A receptor (GABAA) subunits and sodium channel genes, especially GABRG2 and SCN1A, have been reported to be associated with febrile seizures (FS) and genetic epilepsy with febrile seizures plus (GEFS+). GEFS+ is a well-known family of epileptic syndrome with autosomal dominant inheritance in children. Its most common phenotypes are febrile seizures often with accessory afebrile generalized tonic-clonic seizures, febrile seizures plus (FS+), severe epileptic encephalopathy, as well as other types of generalized or localization-related seizures. However, the pathogenesis of febrile seizures remains largely unknown. Here, we generated a GABRG2 gene knockout cell line (HT22GABRG2KO) by applying the CRISPR/Cas9-mediated genomic deletion in HT-22 mouse hippocampal neuronal cell line to explore the function of GABRG2 in vitro. With mRNA-seq, we found significant changes in the expression profiles of several epilepsy-related genes when GABRG2 was knockout, some of them showing temperature-induced changes as well. Kyoto Encyclopedia Gene and Genomic (KEGG) analysis revealed a significant alteration in the MAPK and PI3K-Akt signaling pathways. We also observed an up-regulation of the matrix metalloproteinases (MMPs) family after GABRG2 knockout. Furthermore, the significant decrease in expression of GABRA1 and CACNA1A (but not others) with an increase in temperature is a novel finding. In summary, mutations in the GABAA receptor can lead to a decrease in numbers of receptors, which may cause the impairment of GABAergic pathway signaling. This data has been the first time to reveal that GABRG2 mutations would affect the function of other genes, and based on this finding we hope this work would also provide a new direction for the research of GABRG2 in GEFS+. It also may provide a molecular basis for the severity of epilepsy, and guide the clinical medication for the treatment of the epilepsy focused on the function on GABAA receptors, which, might be a new strategy for genetic diagnosis and targeted treatment of epilepsy.

(Energy Technology Division Graduate Student Award Address sponsored by Bio-Logic) Understanding Charge Transport for Current and Future Electrochemical Energy Storage Technologies

Advances in electrochemical energy storage are key for the integration of intermittent wind and solar energy sources into the grid, widespread adoption of electric vehicles, and development of new safe and reliable consumer devices. For grid, transportation, and electronic energy storage markets, each application has distinct needs. Therefore, developing battery technology for emerging and wide-spread applications demands greater understanding of the complex chemical and electrochemical processes that occur within rechargeable batteries. Electron transfer and ion transport are the foundation of battery function where the capacity, loaded voltage and current define the practical energy and power delivery of the system. During operation, repetitive addition and removal of electrons and ions can lead to structural change within the electrode and interfacial formation that can dramatically impact electrochemical outcomes. Thus, structural, chemical, and electrochemical characterization during operation is critically important for next generation electrochemical energy storage technologies. The research efforts highlighted in this talk use multiple advanced characterization techniques, including operando based methods, to probe charge transport properties, structural changes, and interfacial evolution in multiple rechargeable battery systems. Specifically, X-ray absorption spectroscopy enabled structure and oxidation state elucidation in the absence of long-range order. Isothermal microcalorimetry was used to determine heat evolution due to parasitic or decomposition reactions operando. X-ray diffraction was employed to track temperature-induced and lithiation-induced phase changes of distinct electroactive materials. Using advanced characterization, these research efforts provide insight into electron transfer and ion transport properties and their impact on application relevant outcomes (resistance, cycle life, delivered capacity) of electrochemical energy storage technologies.

Smooth pyroelectric luminescence in LiNbO3 single crystals

We investigate the phenomenon of pyroelectric luminescence in LiNbO3 single crystals. This faint emission of light due to temperature-induced changes of permanent polarization is induced by different types of charge carrier recombination, outside and inside the crystal. With decreasing atmospheric pressure, the external discharge mechanism transitions from sparse intense gas discharge pulses at ambient pressure, to frequent faint discharges close to 1 mbar, to a continuous emission which is referred to as smooth pyroelectric luminescence. Our experimental setup exposes the crystal to constant positive and negative temperature changes in the range of 360–450 K under high vacuum while simultaneously measuring the surface charge density and the emitted intensity. A microscopic model of the luminescence allows the description of the time-dependent pyroelectric luminescence, in particular the determination of deep trap potentials that are otherwise inaccessible to thermal ionization. Using this model, we show that the behavior of this emission in LiNbO3 crystals is consistent with the release of trapped electrons by the Poole–Frenkel effect from a Dirac-well potential, while the commonly assumed coulombic trap shape is in clear disagreement with both the temporal evolution of the emission as well as the magnitude of the electric field obtained in our measurements.

Intragenic meiotic recombination in Schizosaccharomyces pombe is sensitive to environmental temperature changes

Changes in environmental temperature influence cellular processes and their dynamics, and thus affect the life cycle of organisms that are unable to control their cell/body temperature. Meiotic recombination is the cellular process essential for producing healthy haploid gametes by providing physical links (chiasmata) between homologous chromosomes to guide their accurate segregation. Additionally, meiotic recombination—initiated by programmed DNA double-strand breaks (DSBs)—can generate genetic diversity and, therefore, is a driving force of evolution. Environmental temperature influencing meiotic recombination outcome thus may be a crucial determinant of reproductive success and genetic diversity. Indeed, meiotic recombination frequency in fungi, plants and invertebrates changes with temperature. In most organisms, these temperature-induced changes in meiotic recombination seem to be mediated through the meiosis-specific chromosome axis organization, the synaptonemal complex in particular. The fission yeast Schizosaccharomyces pombe does not possess a synaptonemal complex. Thus, we tested how environmental temperature modulates meiotic recombination frequency in the absence of a fully-fledged synaptonemal complex. We show that intragenic recombination (gene conversion) positively correlates with temperature within a certain range, especially at meiotic recombination hotspots. In contrast, crossover recombination, which manifests itself as chiasmata, is less affected. Based on our observations, we suggest that, in addition to changes in DSB frequency, DSB processing could be another temperature-sensitive step causing temperature-induced recombination rate alterations.

Examining the Direct and Indirect Effects of Climatic Variables on Plague Dynamics

Climate change can influence infectious disease dynamics both directly, by affecting the disease ecology, and indirectly, through altering economic systems. However, despite that climate-driven human plague dynamics have been extensively studied in recent years, little is known about the relative importance of the direct and indirect effects of climate change on plague outbreak. By using Structural Equation Modeling, we estimated the direct influence of climate change on human plague dynamics and the impact of climate-driven economic change on human plague outbreak. After studying human plague outbreak in Europe during AD1347–1760, we detected no direct climatic effect on plague dynamics; instead, all of the climatic impacts on plague dynamics were indirect, and were operationalized via economic changes. Through a series of sensitivity checks, we further proved that temperature-induced economic changes drove plague dynamics during cold and wet periods, while precipitation-induced economic changes drove plague dynamics during the cold periods. Our results suggest that we should not dismiss the role of economic systems when examining how climate change altered plague dynamics in human history.

Optical conductivity of multifold fermions: The case of RhSi

We measured the reflectivity of the multifold semimetal RhSi in a frequency range from 80 to 20000 cm$^{-1}$ (10 meV - 2.5 eV) at temperatures down to 10 K. The optical conductivity, calculated from the reflectivity, is dominated by the free-carrier (Drude) contribution below 1000 cm$^{-1}$ (120 meV) and by interband transitions at higher frequencies. The temperature-induced changes in the spectra are generally weak: only the Drude bands narrow upon cooling, with an unscreened plasma frequency that is constant with temperature at approximately 1.4 eV, in agreement with a weak temperature dependence of the free-carrier concentration determined by Hall measurements. The interband portion of conductivity exhibits two linear-in-frequency regions below 5000 cm$^{-1}$ ($\sim$ 600 meV), a broad flat maximum at around 6000 cm$^{-1}$ (750 meV), and a further increase starting around 10000 cm$^{-1}$ ($\sim$ 1.2 eV). We assign the linear behavior of the interband conductivity to transitions between the linear bands near the band crossing points. Our findings are in accord with the predictions for the low-energy conductivity behavior in multifold semimetals and with earlier computations based on band structure calculations for RhSi.