Temperature Components Research Articles

A novel exploration of magnetized nano Jeffrey fluid flow over a chemically reacted permeable disk with ohmic heating

Swirling flows are important in rheological devices, spin coatings and lubrication, so we set out to investigate what makes chemically reactive non-Newtonian spinning flows across a disk with a radially applied magnetic field so interesting. Nanofluids are thermally enhanced working fluids with many interesting physical properties. This study takes its inspiration from rotating disk oxidations used in the medical techno industry and builds a mathematical model of a continuous convective von Kármán swirling flow including Jeffrey, magnetic, Joule/ohmic and chemical reactions. The wall anisotropy slips and the concentration-induced blowing effects are included. By using the bvp4c approach, the transformed boundary conditions (BCs) are addressed. Graphical representations of the effects of involved parameters on the density distribution of motile microorganisms, concentration, temperature and dimensionless velocity components are shown. Supporting evidence from prior research is included. Novel bioreactors, membrane oxygenators, bio-chromatography and food processing should take note of the study’s findings. As Jeffrey’s parameter upsurges, there is a decrease in radial velocity. As the Jeffrey parameter increases, there is a decrease in the circumferential velocity. Radial flow is significantly enhanced near the wall as the radial slip parameter ([Formula: see text] increases. As the Eckert number grows, the quantity of temperature increases. Concentration distribution closer to the disk to grow as Le increases. The concentration and diffusivity of microorganisms drop as the number of motile microorganisms thickens.

Численное моделирование смешанной конвекции в жидком металле при подъемном течении по круглой обогреваемой трубе в условиях поперечного магнитного поля

Hydrodynamics and heat transfer in mixed convection of liquid metal (Pr=0.025) in a vertical pipe with an upward flow in a transverse magnetic field are considered. The study was carried out using a direct numerical simulation method. Simulations were performed at Reynolds numbers up to 12,000, Richardson numbers from 0 to 2.4 and Hartmann numbers up to 550 for two limiting cases of pipe wall conductivity. The simulation results for an isolated pipe were compared with the measurement data from the mercury experiments. The effect of the transverse magnetic field is manifested in the suppression of turbulent transfer and flow laminarization with the formation of strong inhomogeneity of the longitudinal velocity profile by angle and gradients of the streamwise velocity in the transverse direction. Depending on the pipe wall conductivity and the ratios of such parameters as Richardson and Hartmann numbers, the resulting flows with different topology of the longitudinal velocity profile determine the wall temperature distribution in the wall and the values of the heat transfer coefficients. It is shown that in a magnetic field in the case of isolated walls with an increase in the Richardson number the flow has a tendency to instability, which develops in the jets formed in the region of Roberts layers. The periodic process of development and breakage of jets leads to the emergence and development of vortex structures that persist in the magnetic field and cause fluctuations in the velocity and temperature components in the flow. The dependence of the friction factor and heat transfer (Nusselt number) on the Richardson number is obtained.

Novel multi-physics simulation of transient dynamics in functionally graded porous multiferroic cylindrical shells under moving heat flux: A magneto-electro-thermoelastic analysis

Cylindrical structures, such as pipelines in power plants and novel energy-harvesting devices that combine flexible piezoelectric/piezomagnetic layers with other materials, are frequently exposed to moving heat fluxes. Understanding the physics of these structures can provide potential solutions for stress management and energy harvesting. This study investigates, for the first time, the effect of thermal wave propagation on the transient fully coupled magneto-electro-thermoelastic (METE) response of functionally graded porous (FGP) multiferroic cylindrical shells subjected to a partially distributed moving heat flux. The structure is supported by a distributed viscoelastic Winkler-Pasternak foundation, and its mechanical and electromagnetic boundary conditions are considered to be simply supported and suitably grounded. This approach is innovative as it represents the first extension of the three-dimensional (3D) Lord-Shulman coupled thermoelasticity theory to specifically address multiphysics materials. In this updated framework, the governing equations for the motion of each layer are derived following an orthotropic laminated model. To solve the problem, the state-space technique and the mathematical model of the transfer matrix are employed. The study evaluates the structure's vibrational behavior by examining four models of porosity distributions within the thermoelastic layer: symmetric, stiff non-symmetric, soft non-symmetric, and uniform. The key parameters of the dynamic response are calculated using Durbin’s numerical Laplace inversion algorithm. Subsequently, to validate the proposed model, the results are compared with the findings obtained by other researchers. Comprehensive numerical results concerning temporal and spatial variations of temperature, transverse displacement, and stress components are presented for various influencing parameters such as volume fraction index, open or closed-circuit conditions, heat flux speed, porosity, and smart layer thickness.

A Long-duration Superflare on the K Giant HD 251108

Many giant stars are magnetically active, which causes rotational variability, chromospheric emission lines, and X-ray emission. Large outbursts in these emission features can set limits on the magnetic field strength and thus constrain the mechanism of the underlying dynamo. HD 251108 is a Li-rich active K-type giant. We find a rotational period of 21.3 days with color changes and additional long-term photometric variability. Both can be explained with very stable stellar spots. We followed the decay phase of a superflare for 28 days with NICER and from the ground. We track the flare decay in unprecedented detail in several coronal temperature components. With a peak flux around 1034 erg s−1 (0.5–4.0 keV) and an exponential decay time of 2.2 days in the early decay phase, this is one of the strongest flares ever observed, yet it follows trends established from samples of smaller flares, for example, for the relations between Hα and X-ray flux, indicating that the physical process that powers the flare emission is consistent over a large range of flare energies. We estimate a flare loop length about 2–4 times the stellar radius. No evidence is seen for abundance changes during the flare.

Influence of Cutting Surface Condition and Composition on High-Temperature Oxidation Behavior of Ti2 Al C MAX Phase Ceramics

Ti2AlC, one of the MAX phase ceramics, has metal-like properties (electrical conductivity, high fracture toughness and good machinability) and ceramic-like properties (low density, high-temperature oxidation resistance and high bending strength). Ti2AlC ceramics can be cut with cemented carbide tools and the mechanical strength does not decrease significantly after cutting. Ti2AlC ceramics have potential as high-strength machinable ceramics for use in high temperature components. However, the oxidation resistance of Ti2AlC ceramics decreases after cutting because the cutting damages inhibit the formation of protective Al2O3 scale. There are few discussions on the effect of cutting surface conditions on oxidation resistance of Ti2AlC ceramics. The continued growth of the protective Al2O3 scale requires a sufficient Al supply during high-temperature oxidation. The oxidation resistance of Ti2AlC ceramics is reduced when a non-protective TiO2 scale forms on the surface. As one of the common methods to prevent the growth of the TiO2 scale is Nb addition in Ti-based alloys and compounds. The oxidation resistance of as-machined Ti2AlC ceramics may be improved by increasing the amount of Al and Nb additions. This study reports the influences of cutting surface conditions and composition on oxidation behavior of Ti2AlC ceramics. Commercial Ti, Al, C and Nb powders were mixed in Ti:Al:C:Nb molar ratios of 2:1.2:0.9:0 and 1.9:1.2:0.9:0.1 with the corresponding samples receiving the designations Al1 and Al1.2Nb. The powder mixture was annealed for 12 h in a vacuum at 1300°C. The synthesized powder was consolidated over 15 min using a pulsed electric current sintering technique at 1300°C, in a vacuum, and under a uniaxial pressure of 30 MPa. The phases present in the sintered samples were also identified by XRD. Milling tests were performed on a 4 x 4 mm sample surface using a 2 mm diameter end-mill mounted on a plane milling machine. Dry cutting was performed with a spindle speed, feed rate, and cut depth of 4000 rpm, 46 mm/min, and 100 μm. Threading tests were cut into an JIS-M6 bolt shape with a thickness of 3 mm with a lathe and diamond saw. The surface roughness of each sample was measured using a surface texture measuring instrument. The samples were heated in an electric furnace at 1200°C for 4 h in laboratory air. The surface and cross-sections of the oxidized samples were observed via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX).The main peaks of all sintered samples in these XRD patterns were identified as originating from Ti2AlC and minor peaks originating from TiAl3 (Al-rich phase). The average arithmetic mean roughness (R a) values of the end-milled and threaded surfaces were 0.8 and 4.5 μm. The SEM and EDX results show that a continuous Al2O3 scale formed on the end-milled surface of Al1.2 and Al1.2Nb after the oxidation test. The results of SEM and EDX investigations indicate that a non-protective TiO2 scale had formed on the threaded surface of Al1 and a continuous Al2O3 scale with a thickness of less than 4 μm was formed on the threaded surface of Al1.2Nb after the oxidation test. The Al-rich phase provided the Al necessary for the formation of a continuous Al2O3 scale on the end-milled surface. The oxidation resistance of Ti2AlC ceramics was greatly reduced in the case of screw-like shapes with high R a values and many corners on the cutting surface. The addition of Nb improves the oxidation resistance of Ti2AlC ceramics under such cutting surface conditions. The cause of non-protective oxidation was the destruction of the Al2O3 scale because of the growth of TiO2 scale. The TiO2 scale tends to form at corners where continuous Al2O3 scale formation is difficult. One of the factors that improves the oxidation resistance of Ti2AlC ceramics with screw shapes is the suppression of TiO2 growth by Nb addition. The higher Al concentration and the addition of Nb remarkably increase the oxidation resistance of the Ti2AlC ceramics after cutting.

Construction of a numerical model for cigarette smoking and combustion and simulation of combustion cone shape

Abstract Understanding the thermal conditions inside a burning cigarette is a top priority for controlling chemical emissions and cigarette design. Since experimental methods are difficult to observe in depth, this paper starts from the perspective of numerical simulation and models the structure of the tobacco distribution of the cigarette, integrating the end surface ignition model, puffing model, chemical reaction model, heat and mass transfer and diffusion model have established a three-dimensional comprehensive model that can represent the changes in combustion cone morphology during cigarette combustion. The model covers chemical reaction and mass transfer as well as generation, flow and reaction mechanism. The simulation results show that the model can better predict the temperature distribution, component distribution and combustion cone morphology changes during cigarette smoking and combustion. It provides an effective means for in-depth research on cigarette combustion.

Device Reliability of Negative Capacitance Source Pocket Double Gate TFETs: A Study on Temperature and Noise Effects

This study investigates the reliability of a negative capacitance source pocket double gate tunnel field-effect transistor (NC-SP-DGTFET) by examining the effects of temperature and various noise components on its performance. The research focuses on key DC parameters, including the transfer characteristics, subthreshold swing, and the ION/IOFF ratio, evaluated across a temperature range from 250 to 450 K. Additionally, the study explores the radio-frequency performance of the device by assessing how temperature impacts transconductance (gm), cut-off frequency (fT), gate capacitance (Cgg), intrinsic delay, and the transconductance frequency product. Noise performance metrics are also analyzed, focusing on the drain current noise power spectral density (SID) and gate voltage noise power spectral density (SVG). The study considers the contributions of diffusion, generation-recombination (G-R), and flicker noise components and at 300 K, SID and SVG showed peak values of 5.08 × 10−26 A2/Hz and 2.67 × 10−16 V2/Hz, 5.73 × 10−18 A2/Hz and 3.22 × 10−10 V2/Hz, and 1.33 × 10−25 A2/Hz and 1.19 × 10−14 V2/Hz, respectively. The analysis reveals that flicker noise is predominant at lower frequencies, while diffusion noise becomes more significant at higher frequencies. However, G-R noise is the most dominant across all frequencies examined. These findings provide crucial insights for optimizing the design and performance of NC-SP-DGTFETs in low-power applications.

IPA: Class 0 Protostars Viewed in CO Emission Using JWST

We investigate the bright CO fundamental emission in the central regions of five protostars in their primary mass assembly phase using new observations from JWST’s Near-Infrared Spectrograph and Mid-Infrared Instrument. CO line emission images and fluxes are extracted for a forest of ∼150 rovibrational transitions from two vibrational bands, v = 1−0 and v = 2−1. However, 13CO is undetected, indicating that 12CO emission is optically thin. We use H2 emission lines to correct fluxes for extinction and then construct rotation diagrams for the CO lines with the highest spectral resolution and sensitivity to estimate rotational temperatures and numbers of CO molecules. Two distinct rotational temperature components are required for v = 1 (∼600 to 1000 K and 2000 to ∼104 K), while one hotter component is required for v = 2 (≳3500 K). 13CO is depleted compared to the abundances found in the interstellar medium, indicating selective UV photodissociation of 13CO; therefore, UV radiative pumping may explain the higher rotational temperatures in v = 2. The average vibrational temperature is ∼1000 K for our sources and is similar to the lowest rotational temperature components. Using the measured rotational and vibrational temperatures to infer a total number of CO molecules, we find that the total gas masses range from lower limits of ∼1022 g for the lowest mass protostars to ∼1026 g for the highest mass protostars. Our gas mass lower limits are compatible with those in more evolved systems, which suggest the lowest rotational temperature component comes from the inner disk, scattered into our line of sight, but we also cannot exclude the contribution to the CO emission from disk winds for higher mass targets.

Turbulent fluxes of aerosol and heat in a desertified area during intermittent emission of dust aerosol

Based on fluctuations measurement results in the components of wind speed, air temperature and concentration of aerosol particles on a desertified area in the Astrakhan region under conditions of intermittent emission of dust aerosol, vertical turbulent fluxes of dust aerosol and heat were determined. Using spectral analysis, the temporal variability of the horizontal and vertical components of wind speed, air temperature and concentration of dust aerosol particles was characterized. It is shown that the intermittent emission of the dust aerosol is determined by low-frequency convective-induced variations in the horizontal component of wind speed when the threshold saltation speed is exceeded. Significant differences in the spatiotemporal variability of vertical heat transfer and dust aerosol were revealed. The 30-minute average values of heat fluxes (90–158 W/m2) and dust aerosol (7.2–27.5 cm–2cm–1), as well as the rate of heat removal (14–21 cm/s) and dust aerosol (10–16 cm/s).

Future Projection of Water Resources of Ruzizi River Basin: What Are the Challenges for Management Strategy?

This study investigates the impact of climate change on hydrological dynamics in the Ruzizi River Basin (RRB) by leveraging a combination of observational historical data and downscaled climate model outputs. The primary objective is to evaluate changes in precipitation, temperature, and water balance components under different climate scenarios. We employed a multi-modal ensemble (MME) approach to enhance the accuracy of climate projections, integrating historical climate data spanning from 1950 to 2014 with downscaled projections for the SSP2-4.5 and SSP5-8.5 scenarios, covering future periods from 2040 to 2100. Our methodology involved calibrating and validating the SWAT model against observed hydrological data to ensure reliable simulations of future climate scenarios. The model’s performance was assessed using metrics such as R2, NSE, KGE, and PBIAS, which closely aligned with recommended standards. Results reveal a significant decline in mean annual precipitation, with reductions of up to 37.86% by mid-century under the SSP5-8.5 scenario. This decline is projected to lead to substantial reductions in surface runoff, evapotranspiration, and water yield, alongside a marked decrease in mean monthly stream flow, critically impacting agricultural, domestic, and ecological water needs. The study underscores the necessity of adaptive water resource management strategies to address these anticipated changes. Key recommendations include implementing a dynamic reservoir operation system, enhancing forecasting tools, and incorporating green infrastructure to maintain water quality, support ecosystem resilience, and ensure sustainable water use in the RRB. This research emphasizes the need for localized strategies to address climate-driven hydrological changes and protect future water resources.

Long-term geomagnetic activities and stratospheric winter temperature

In this research, impact of long term solar forcing on stratospheric winter temperature is checked. The 11- year sunspot activity and geomagnetic indices (AE, Kp, Dst) are used as an indicator for solar forcing, as geomagnetic activity indices show good correlation with solar variability. To understand the impact of solar forcing through high latitude, stratospheric winter (November to March) time North Polar Region (60N–90N) temperature anomalies are considered. The findings showed that temperature changes in the stratosphere are significantly correlated with solar activity, as evidenced by a significant positive correlation between the 11-year moving mean of stratospheric (10 hPa) temperature anomalies and sunspot number. Approximately from 1970 to 2000, the North Polar Region saw positive anomalous stratospheric winter temperatures. During the same time, the geomagnetic activity also showed a substantial increase. The year-to-year correlation between stratospheric pole temperature and geomagnetic activity is significant (about 0.5). The Empirical Mode Decomposition analysis reveals a highly significant correlation (around 0.9) between the long-term component of stratospheric winter temperature (IMF-4) and the long-term component of geomagnetic activity (IMF-3 and IMF-4). One of the reasons for the increase in lower stratospheric temperature is an increase in ozone concentration during the same period when geomagnetic activity is higher. Empirical orthogonal function (EOF) and correlation analysis of stratospheric winter temperature with large-scale circulation patterns are also carried out. The spatial correlation is checked for stratospheric winter temperature at North Pole and lower atmospheric levels (250 hPa and 850 hPa) followed by pre-monsoon and monsoon season. This study includes statistical analysis, however, also highlights the necessity of in-depth dynamical analysis to improve our understanding of how solar activity impacts Earth's atmospheric layers, which may be helpful in predicting the weather and climate.

Scaling of vertical coherence and logarithmic energy profile for wall-attached eddies during sand and dust storms

High-frequency observation data, including all three components of instantaneous fluctuating velocity, temperature, as well as particulate matter 10 ( $PM_{10}$ ), collected from the unstable atmospheric surface layer at $z/L = -0.11$ and $-$ 0.12, $L$ being the Obukhov length, during sand and dust storms (SDS), were used to explore the scaling of vertical coherence and the logarithmic energy profile for wall-attached eddies. The present results demonstrate good agreement with the self-similar range of the wall-attached features for velocity and temperature components, as well as for $PM_{10}$ at lower heights ( $z<15$ m) during SDS. Following the idea depicted by Davenport (Q. J. R. Meteorol., vol. 372, 1961, pp. 194–211), an empirically derived transfer kernel comprises implicit filtering via a scale-dependent gain and phase, parametrically defined as $|H_L^2(f)|=\exp (c_1-c_2\delta /\lambda _x)$ , where $c_1$ and $c_2$ are parameters, $\delta$ is the boundary layer thickness and $\lambda _x$ is the streamwise wavelength. Linear coherence spectrum analysis is applied as a filter to separate the coherent and incoherent portions. After this separation procedure, the turbulence intensity decay for wall-attached eddies is described in a log–linear manner, which also identifies how the scaling parameter differs between the measured components. These findings present abundant features of wall-attached eddies during SDS which further are used to improve/enrich existing near-wall models.

Two Perspectives on Amplified Warming over Tropical Land Examined in CMIP6 Models

Abstract Climate change projections show amplified warming associated with dry conditions over tropical land. We compare two perspectives explaining this amplified warming: one based on tropical atmospheric dynamics and the other focusing on soil moisture and surface fluxes. We first compare the full spatiotemporal distribution of changes in key variables in the two perspectives under a quadrupling of CO2 using daily output from the CMIP6 simulations. Both perspectives center around the partitioning of the total energy/energy flux into the temperature and humidity components. We examine the contribution of this temperature/humidity partitioning in the base climate and its change under warming to rising temperatures by deriving a diagnostic linearized perturbation model that relates the magnitude of warming to 1) changes in the total energy/energy flux, 2) the base-climate temperature/humidity partitioning, and 3) changes in the partitioning under warming. We show that the spatiotemporal structure of warming in CMIP6 models is well predicted by the inverse of the base-climate partition factor, which we term the base-climate sensitivity: conditions that are drier in the base climate have a higher base-climate sensitivity and experience more warming. On top of this relationship, changes in the partition factor under intermediate (between wet and dry) surface conditions further enhance or dampen the warming. We discuss the mechanistic link between the two perspectives by illustrating the strong relationships between lower-tropospheric temperature lapse rates, a key variable for the atmospheric perspective, and surface fluxes, a key component of the land surface perspective. Significance Statement Understanding what conditions give rise to the largest magnitude of warming in response to rising CO2 concentrations is not only scientifically important but also critical from a climate impact standpoint. Two main perspectives, one focusing on atmospheric dynamics and the other focusing on land surface processes, have been proposed to explain the stronger warming associated with drier conditions in the tropics. Here, we compare and contrast these two perspectives. We demonstrate that amplified warming in CMIP6 models can largely be predicted from base-climate dryness alone in both perspectives but is further modified based on changes in the partitioning of energy between temperature and moisture. We highlight the spatiotemporal conditions where assumptions in the two perspectives hold and where deviations occur within CMIP6 climate models.

Spectral properties of ablating meteorite samples for improved meteoroid composition diagnostics

Emission spectra and diagnostic spectral features of a diverse range of ablated meteorite samples with a known composition are presented. We aim to provide a reference spectral dataset to improve our abilities to classify meteoroid composition types from meteor spectra observations. The data were obtained by ablating meteorite samples in high-enthalpy plasma wind tunnel facilities recreating conditions characteristic of low-speed meteors. Near-UV to visible-range (320–800 nm) emission spectra of 22 diverse meteorites captured by a high-resolution Echelle spectrometer were analyzed to identify the characteristic spectral features of individual meteorite groups. The same dataset captured by a lower-resolution meteor spectrograph was applied to compare the meteorite data with meteor spectra observations. Spectral modeling revealed that the emitting meteorite plasma was characterized by temperatures of 3700–4800 K, similar to the main temperature component of meteors. The studied line intensity variations were found to trace the differences in the original meteorite composition and thus can be used to constrain the individual meteorite classes. We demonstrate that meteorite composition types, including ordinary chondrites, carbonaceous chondrites, various achondrites, stony-iron and iron meteorites, can be spectrally distinguished by measuring relative line intensities of Mg I, Fe I, Na I, Cr I, Mn I, Si I, H I, CN, Ni I, and Li I. Additionally, we confirm the effect of the incomplete evaporation of refractory elements Al, Ti, and Ca, and the presence of minor species Co I, Cu I, and V I.

Using geographic effect measure modification to examine socioeconomic-related surface temperature disparities in New York City.

Lower socioeconomic (SES) communities are more likely to be situated in urban heat islands and have higher heat exposures than their higher SES counterparts, and this inequality is expected to intensify due to climate change. To examine the relationship between surface temperatures and SES in New York City (NYC) by employing a novel analytical approach. Through incorporating modifiable features, this study aims to identify potential locations where mitigation interventions can be implemented to reduce heat disparities associated with SES. Using the 2013-2017 American Community Survey, U.S Landsat-8 Analysis Ready Data surface temperatures (measured on 8/12/2016), and the NYC Land Cover Dataset at the census tract level (2098 tracts), this study examines the association between two components of tract-level SES (percentage of individuals living below the poverty line and the percentage of individuals without a high school degree) and summer day surface temperature in NYC. First, we examine this association with an unrestricted NYC linear regression, examining the city-wide association between the two SES facets and summer surface temperature, with additional models adjusting for altitude, shoreline, and nature-cover. Then, we assess geographic effect measure modification by employing the same models to three supplemental regression model strategies (borough-restricted and community district-restricted linear regressions, and geographically weighted regression (GWR)) that examined associations within smaller intra-city areas. All regression strategies identified areas where lower neighborhood SES composition is associated with higher summer day surface temperatures. The unrestricted NYC regressions revealed widespread disparities, while the borough-restricted and community district-restricted regressions identified specific political boundaries within which these disparities existed. The GWR, addressing spatial autocorrelation, identified significant socioeconomic heat disparities in locations such as northwest Bronx, central Brooklyn, and uptown Manhattan. These findings underscore the need for targeted policies and community interventions, including equitable urban planning and cooling strategies, to mitigate heat exposure in vulnerable neighborhoods. This study redefines previous research on urban socioeconomic disparities in heat exposure by investigating both modifiable (nature cover) and non-modifiable (altitude and shoreline) built environment factors affecting local temperatures at the census tract level in New York City. Through a novel analytical approach, the research aims to highlight intervention opportunities to mitigate heat disparities related to socioeconomic status. By examining the association between surface temperatures and socioeconomic status, as well as investigating different geographic and governmental scales, this study offers actionable insights for policymakers and community members to address heat exposure inequalities effectively across different administrative boundaries. The objective is to pinpoint potential sites for reducing socioeconomic heat exposure disparities at various geographic and political levels.

Use of mobile metallography to assess the extent of damage to high temperature components in power plants

Abstract Microstructural replicas are used in recurrent testing of hot, pressuriszed components to detect creep damage. The test location must be representative of the damage development and subsequent component failure. Poor preparation leads to the formation of artefacts which are considered in the damage assessment. The assessment is subject to method and operator variability. When assessing the life of components based on microstructure replicas, these must be taken into account and, if necessary, extended stress calculations for the component must be used.

Temperature history reconstruction in steel box girders using limited data and proper orthogonal decomposition-based dimension reduction representation

The monitoring temperature history of steel box girders inevitably contains gaps or anomalies due to the malfunctions of the structural health monitoring system. Traditional methods for reconstructing temperature histories face the challenge in accounting for the randomness of temperature variations caused by the uncertainty of complex environmental factors. This research proposes a framework for reconstructing the long-term temperature of steel box girders by combining the limited measurements with a proper orthogonal decomposition (POD) based dimension reduction representation approach, to account for the stochastic nature of daily temperature variations. Unlike the conventional Monte Carlo-based POD method, the developed POD-based dimension reduction representation approach effectively reduces the number of elementary random variables from thousands to two by introducing random functions serving as constraints, overcoming the challenge of high-dimensional random variables inherent in the Monte Carlo methods. The proposed approach divides the measured temperature histories into random high-frequency (HF) and deterministic low-frequency (LF) components and establishes the theoretical models of power spectral density and coherence functions of HF temperature components to accommodate the generation of HF temperature component samples, and finally reconstructs temperature samples by superimposing the LF components and generated HF component samples. The results from a practical example demonstrate that the statistical characteristics of representative HF temperature component samples generated by the POD-based dimension reduction representation align well with the corresponding targeted values, and the proposed method outperforms the traditional POD method, yielding a 60% efficiency enhancement without compromising computational accuracy. The developed framework owns apparent superiority in accuracy compared to the traditional POD and the long short-term memory methods, particularly in continuous and extensive missing data. Moreover, the reconstructed temperature samples with assigned probabilities present complete probability information from the level of total probability. These results advance the probabilistic methods in tackling long-term temperature history reconstruction.

Enhanced Recognition of a Herbal Compound Epiberberine by a DNA Quadruplex-Duplex Structure.

The small molecule epiberberine (EPI) is a natural alkaloid with versatile bioactivities against several diseases including cancer and bacterial infection. EPI can induce the formation of a unique binding pocket at the 5' side of a human telomeric G-quadruplex (HTG) sequence with four telomeric repeats (Q4), resulting in a nanomolar binding affinity (KD approximately 26 nM) with significant fluorescence enhancement upon binding. It is important to understand (1) how EPI binding affects HTG structural stability and (2) how enhanced EPI binding may be achieved through the engineering of the DNA binding pocket. In this work, the EPI-binding-induced HTG structure stabilization effect was probed by a peptide nucleic acid (PNA) invasion assay in combination with a series of biophysical techniques. We show that the PNA invasion-based method may be useful for the characterization of compounds binding to DNA (and RNA) structures under physiological conditions without the need to vary the solution temperature or buffer components, which are typically needed for structural stability characterization. Importantly, the combination of theoretical modeling and experimental quantification allows us to successfully engineer Q4 derivative Q4-ds-A by a simple extension of a duplex structure to Q4 at the 5' end. Q4-ds-A is an excellent EPI binder with a KD of 8 nM, with the binding enhancement achieved through the preformation of a binding pocket and a reduced dissociation rate. The tight binding of Q4 and Q4-ds-A with EPI allows us to develop a novel magnetic bead-based affinity purification system to effectively extract EPI from Rhizoma coptidis (Huang Lian) extracts.

Temperature and biodiversity influence community stability differently in birds and fishes.

Determining the factors that affect community stability is crucial to understanding the maintenance of biodiversity and ecosystem functioning in the face of global warming. We investigated how four temperature components (that is, median, variability, trend and extremes) affected diversity-synchrony-stability relationships for 1,246 bird and 580 fish communities from temperate regions. We hypothesized a stabilizing effect on the community if the variation in species' response to changing median temperature decreases overall community synchrony (hypothesis H1) and if temperature extremes reduce interspecific synchrony at extreme abundances due to variation in species' thermal tolerance limits (hypothesis H2). We found support for H1 in fish and for H2 in bird communities. Here we showed that the abiotic components (that is, the median, variability, trend and extremes of temperature) had more indirect effects on community stability, predominantly by affecting the biotic components (that is, diversity, synchrony). Considering various temperature components' direct as well as indirect impacts on stability for terrestrial versus aquatic communities will improve our mechanistic understanding of biodiversity change in response to global climatic stressors.

Investigation of the unsteady MHD fluid flow and heat transfer through the porous medium asymmetric wavy channel

This paper uses three analytical methods to find the novel results in the two-dimensional time-dependent MHD oscillatory flow and heat transfer in an asymmetric wavy porous channel. The corresponding constitutive equations become complex by considering the pressure gradient as a complex function. This results in the existence of both real and imaginary solutions for fluid velocity and temperature. The changes in parameters like the Hartmann number, wavelength, Grashof number, and porous medium shape factor will affect the real fluid velocity. Still, only radiation parameter changes will affect the real fluid velocity and temperature. Increasing the Hartmann number, porous medium shape factor, and radiation parameter will drastically reduce real fluid velocity. The Reynolds number should theoretically affect the imaginary velocity, but according to the boundary condition definition, the imaginary velocity value becomes zero. Altering the frequency of the wavy walls and the Peclet number will only affect the imaginary temperature component, and increasing these parameters will increase the average imaginary temperature profile. The uniqueness of this study lies in the resolution of complex differential equations in a way that has not been attempted before. The results indicated that each set of three solutions was nearly identical, highlighting the outcomes' precision.