Well-defined Linear Relationship Research Articles

A simple and highly sensitive flexible sensor with extended-gate field-effect transistor for epinephrine detection utilizing InZnSnO sensing films

This study introduces a straightforward method for depositing InZnSnO films onto flexible polyimide substrates at room temperature, enabling their application in electrochemical pH sensing and the detection of epinephrine. A comprehensive analysis of these sensing films, spanning structural, morphological, compositional, and profiling characteristics, was conducted using diverse techniques, including X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectroscopy. The investigation into the influence of oxygen flow rates on the performance of InZnSnO sensitive films revealed a significant correlation between their structural properties and sensing capabilities. Notably, exposure to an oxygen flow rate of 30/2 (Ar/O2) the ratio of resulted in the InZnSnO sensitive film demonstrating outstanding pH sensitivity at 59.58 mV/pH within a broad pH range of 2–12, surpassing the performance observed with other oxygen flow rates. Moreover, under this specific condition, the film exhibited excellent stability, with a minimal drift rate of 0.14 mV/h at pH 7 and a low hysteresis voltage of 1.8 mV during a pH cycle of 7 → 4→7 → 10→7. Given the critical role of epinephrine in mammalian central nervous and hormone systems, monitoring its levels is essential for assessing human health. To facilitate the detection of epinephrine, we utilized the carboxyl group of 4-formylphenylboronic acid to enable a reaction with the amino group of the 3-aminopropyltriethoxysilane-coated InZnSnO film. Through optimization, the resulting InZnSnO-based flexible sensor displayed a broad and well-defined linear relationship within the concentration range of 10−7 to 0.1 μM. In practical applications, this sensor proved effective in analyzing epinephrine in human serum, showcasing notable selectivity, stability, and reproducibility. The promising outcomes of this study underscore the potential for future applications, leveraging the advantages of electrochemical sensors, including affordability, rapid response, and user-friendly operation.

Mesoporous carbon decorated with MIL-100(Fe) as an electrochemical platform for ultrasensitive determination of trace cadmium and lead ions in surface water

In this work, MIL-100(Fe)-decorated mesoporous carbon powders (MC@MIL-100(Fe)) were prepared by in situ growth of MIL-100(Fe) on the surface of ZIF-8 framework-based mesoporous carbons (MC). The hybrid material was characterized using SEM equipped with EDS mapping for morphology investigation, X-ray photoelectron spectroscopy for chemical valence analysis, and X-ray diffraction for crystal structure determination. The developed sensor separated from the traditional bismuth film decoration, and simultaneously, MC@MIL-100(Fe) was applied for the first time to electrochemically detect trace amounts of Pb(II) and Cd(II). The fabricated MC@MIL-100(Fe)-based electrochemical sensor showed excellent response to the target analytes at –0.55 and − 0.75 V for lead and cadmium ions, respectively. By adjusting some measurement parameters, that is, the loading concentration of MC@MIL-100(Fe), acidity of the HAc-NaAc buffer (ABS), deposition potential, and deposition time, the analytical performance of the proposed electrochemical sensor was examined by exploring the calibration curve, repeatability, reproducibility, stability, and anti-interference under optimized conditions. The response current of the proposed MC@MIL-100(Fe) electrochemical sensor showed a well-defined linear relationship in the concentration ranges of 2–250 and 2–270 μg·L−1 for Cd(II) and Pb(II), respectively. In addition, the detection limits of the sensor for Cd(II) and Pb(II) were 0.18 and 0.15 μg L−1, respectively, which are well below the World Health Organization (WHO) drinking water guideline value. The MC@MIL-100(Fe) can be potentially used as an electrochemical platform for monitoring heavy metals in surface water, with satisfactory results.

Experimental Study of Dynamic Mechanical Properties of Water-Saturated Coal Samples under Three-Dimensional Coupled Static–Dynamic Loadings

It is very important to study the influence of water content on the mechanical properties of coal rock to prevent rock burst and roadway instability under dynamic disturbance. In this study, the split Hopkinson pressure bar (SHPB) test system was applied to conduct three-dimensional dynamic and static impact tests on natural and water-saturated coal samples at different strain rates to determine the dynamic mechanical properties of a series of water-bearing coal samples. Based on the new data, we discuss the strength, deformation, crushing energy dissipation, and fractal characteristics of natural and saturated coal rocks. We specifically focus on the different effects of hydraulic pressure on crack propagation under static and dynamic loads. Our results document a well-defined linear relationship between the peak stress and the strain rate of coal in the natural state and the water-saturated state. Once the impact rate reaches a certain value, a double peak phenomenon is observed, and the curve shows a certain leap. The critical impact velocity of the curve leap is ca. 9.485~10.025 m/s. At the same strain rate, the average peak stress in the water-saturated state is ca. 2.684% higher than that in the natural state. The secant modulus of the two states generally increases with the rise in strain rate, but the scatter of the results is large. The average secant modulus of the water-saturated coal sample increases by 2.309% compared with the natural state. The energy consumption density and absorbed energy of saturated and natural coal samples rise with the increase in strain rate, and both show a well-defined power–function relationship. However, under the same condition, the absorbed energy and absorbed energy density of water-saturated coal samples are higher than that of natural coal samples. The fractal dimension of water-saturated coal rises with the increase in strain rate and energy consumption density, showing a strong linear and quadratic relationship, respectively. Under dynamic loading, the cohesive force, jointly generated by free water and the Stefan effect, hinder the expansion of coal and rock fractures, thus improving the compressive strength of coal and rock. The study provides a reliable theoretical basis for preventing rock burst and providing roadway support.

Macroscopical monolayer films of ordered arrays of gold nanoparticles as SERS substrates for in situ quantitative detection in aqueous solutions.

In this work, macroscopical monolayer films of ordered arrays of gold nanoparticles (MMF-OA-Au NPs) are successfully prepared at the interfaces of toluene-diethylene glycol (DEG) with a water volume fraction of 10% (no more than 25%), which can greatly reduce the electrostatic repulsion among NPs during the self-assembly due to the quick transfer of the remaining citrate ions into the DEG solutions containing water. Thanks to the uniformity in the intensity of SERS signals, the as-prepared MMF-OA-Au NPs transferred onto polydimethylsiloxane (PDMS) as SERS substrates (MMF-OA-Au NP@PDMS) can achieve in situ quantitative detection of the analytes (such as crystal violet and malachite green) in aqueous solutions. Moreover, MMF-OA-Au NP@PDMS as SERS-based pH sensors can directly determine the pH value of the aqueous solution in the range of 3 to 10 by means of the established well-defined linear relationship with the intensity of the peak of νCOO- without any calibration, instead of the intensity ratio of the Raman peaks of νCOO- to ν8a with further calculation. In addition, the as-prepared SERS-based pH sensors can still have excellent long-term durability.

Systematic Relation of Estimated Travel Speed and Actual Travel Speed

Estimated travel speed based on spot speed measurements from detectors has been used as a proxy to actual travel speed. Recently, actual travel speeds become available as vehicles with onboard electronic devices provide actual section travel times. As a result, two different speeds can be estimated for a freeway section at a time interval: estimated travel speed takes the average of the spot speeds collected from each detector within a section at a time interval, and actual travel speed is estimated using the sampled vehicles’ actual journey speeds over the section. This paper compares the difference between estimated and actual travel speeds using both kinematic wave theory and actual observations for different traffic states. The theoretical analysis proves that there is a systematic relationship between the estimated and actual travel speeds that form a well-defined loop shape. The existence of well-defined relations is verified using real traffic speed data collected from a Korean expressway and a California freeway. Empirical analysis shows that the real data of estimated versus actual travel speeds exhibit a well-defined linear relationship rather than loop shape. The analysis also shows that the estimated travel speed is generally greater than the actual travel speed due not only to the systematic difference between estimated and actual travel speeds but also to the inherent characteristics of speed data from loop detectors. This finding provides a groundwork to calibrate the widely used estimated travel speed by exploiting the actual travel speeds that were provided by a subset of vehicles in traffic.

Fiber-loop ring-down magnetic field and temperature sensing system based on the principle of time-division multiplexing

A combined magnetic field and temperature sensing system based on the principle of time-division multiplexing was developed. A fiber-loop ring-down technique was introduced to enhance the stability and sensitivity of the system. Magnetic sol-gel was coated onto a single-mode fiber with its cladding partly etched to form the magnetic field sensor head. A temperature-deformation converter was employed in the temperature sensing unit. A delay fiber was used to adjust the decaying pulses of the two sensing units. The influence of temperature on the magnetic field sensor head was experimentally investigated. The magnetic field strength exhibited a well-defined linear relationship with respect to the inverse of the ring-down time over a range of 25–70mT with a sensitivity of 12.7ns/mT, and the temperature showed a well-defined linear relationship between 20.3°C and 79.7°C with a sensitivity of 3.53ns/°C when the magnetic field intensity was 25mT.

Electric field metrology for SI traceability: Systematic measurement uncertainties in electromagnetically induced transparency in atomic vapor

We investigate the relationship between the Rabi frequency (ΩRF, related to the applied electric field) and Autler-Townes (AT) splitting, when performing atom-based radio-frequency (RF) electric (E) field strength measurements using Rydberg states and electromagnetically induced transparency (EIT) in an atomic vapor. The AT splitting satisfies, under certain conditions, a well-defined linear relationship with the applied RF field amplitude. The EIT/AT-based E-field measurement approach derived from these principles is currently being investigated by several groups around the world as a means to develop a new SI-traceable RF E-field measurement technique. We establish conditions under which the measured AT-splitting is an approximately linear function of the RF electric field. A quantitative description of systematic deviations from the linear relationship is key to exploiting EIT/AT-based atomic-vapor spectroscopy for SI-traceable field measurement. We show that the linear relationship is valid and can be used to determine the E-field strength, with minimal error, as long as the EIT linewidth is small compared to the AT-splitting. We also discuss interesting aspects of the thermal dependence (i.e., hot- versus cold-atom) of this EIT-AT technique. An analysis of the transition from cold- to hot-atom EIT in a Doppler-mismatched cascade system reveals a significant change of the dependence of the EIT linewidth on the optical Rabi frequencies and of the AT-splitting on ΩRF.

A Statistical Test for Identifying the Number of Creep Regimes When Using the Wilshire Equations for Creep Property Predictions

A new parametric approach, termed the Wilshire equations, offers the realistic potential of being able to accurately lift materials operating at in-service conditions from accelerated test results lasting no more than 5000 hours. The success of this approach can be attributed to a well-defined linear relationship that appears to exist between various creep properties and a log transformation of the normalized stress. However, these linear trends are subject to discontinuities, the number of which appears to differ from material to material. These discontinuities have until now been (1) treated as abrupt in nature and (2) identified by eye from an inspection of simple graphical plots of the data. This article puts forward a statistical test for determining the correct number of discontinuities present within a creep data set and a method for allowing these discontinuities to occur more gradually, so that the methodology is more in line with the accepted view as to how creep mechanisms evolve with changing test conditions. These two developments are fully illustrated using creep data sets on two steel alloys. When these new procedures are applied to these steel alloys, not only do they produce more accurate and realistic looking long-term predictions of the minimum creep rate, but they also lead to different conclusions about the mechanisms determining the rates of creep from those originally put forward by Wilshire.

Effects of the substitution of Al for Mn on structure, magnetic, and magnetocaloric properties in MnCoGe

The magnetic transition can be controlled by partial substitution of Al for Mn in Mn1−xAlxCoGe, leading to a wide transition temperature range around the room temperature. A well-defined linear relationship between the magnetic entropy change (|ΔSM|) and H2/3 demonstrates the second-order character of magnetic transition. In the case of x = 0.02, the relative cooling power of 242.3 J·kg−1 is achieved for Δμ0H = 5 T at 270.5 K. Interestingly, a corresponding monotonical decline in |ΔSM| is in relation to magnetic moment per formula unit. The observed large relative cooling power with wide phase transition temperatures makes these materials promising for room-temperature magnetic cooling applications.

Magnetic field sensor using the fiber loop ring-down technique and an etched fiber coated with magnetic fluid

The fiber loop ring-down spectroscopy technique is introduced into the evanescent-field-based sensing scheme in order to create a new type of fiber-based magnetic field sensor. As a consequence, the sensitivity and stability of the magnetic field sensing system are significantly enhanced. The sensor head is constructed using a section of a single-mode fiber with its cladding partially etched. The process of fiber etching is described in detail, and the relationship between the diameter of the etched fiber and the etching time is experimentally investigated. After adopting the appropriate size of the etched fiber, the final experimental results show that the magnetic field strength has a well-defined linear relationship with the inverse of the ring-down time τ over a range of 30mT with a sensitivity of 95.5ns/mT.

Potential Stable Low-Permeation Rate Standard Based on Micro-machined Silicon.

Silicon wafers with micro-machined holes were evaluated for use as low-permeation-rate standard artifacts. Accuracy, stability, and reliability were assessed. Two independent experimental techniques for evaluating permeation were used: chilled mirror hygrometer and mass loss. The wafers exhibited a well-defined linear relationship between hole area and resultant water partial pressure for both techniques, although the mass loss curve exhibited a constant vertical offset from the hygrometer curve, attributed to water loss through the O-ring seal. In contrast to polymer permeation standards, Si wafers provided long-term reproducible permeation rates. However, they were also highly fragile, with most of them cracking during the course of the investigation.

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

The Silltal Fault is the northern brittle continuation of the Brenner Fault Zone, marked by a narrow zone of cataclasis and, in three locations, clay-rich fault gouges. The clay mineral composition of these gouges is dominated by higher temperature 2M1 polytype illite/muscovite, with no 1M/1Md illite or mixed layer illite/smectite detected. Smectite is limited to the northern samples from the Stephansbrucke location, whereas chlorite is present in all samples. The K–Ar ages from the different sample size fractions (<0.1, <0.4, <2, 2–6, 6–10 μm, “whole rock gouge”) show a wide spread, from ca. 115 to 12 Ma, with ages consistently decreasing with grain size. Although the ranges overlap, ages from the northern Stephansbrucke samples are generally older (115–36 Ma) than those from the south near Matrei (55–12 Ma), possibly reflecting increasing regional metamorphic temperatures to the south. The well-defined linear relationship between apparent age and hydrogen stable isotope (δD) values establishes a direct correlation between rejuvenation of the K–Ar system and increased interaction with meteoric water introduced and focussed within the fault zone. The dependence of both apparent age and δD on grain size also indicates that radiogenic and stable isotope exchange was controlled by grain size, reflecting new 2M1 illite growth, mechanical grinding of protolith muscovite during cataclastic faulting, or both. The results demonstrate the advantages of combining radiogenic and stable isotope analysis in interpretation of K–Ar ages from clay fault gouges. The combined approach was necessary to establish the crucial influence on apparent K–Ar ages of meteoric water influx focussed on the fault zone and its interaction with clay-size-fraction grains.

A biomimetic enzyme modified electrode for H2O2 highly sensitive detection.

An efficient catalyst based on artificial bionic peroxidase was synthesized for electrocatalysis. A poly(ethyleneimine)/Au nanoparticle composite (PEI-AuNP) was prepared and it was then linked to hemin via a coupling reaction between carboxyl groups in hemin and amino groups in PEI without the activation of a carboxyl group by carbodiimide. Fourier transform infrared (FTIR) spectroscopy verified the formation of amido bonds within the structure. The presence of AuNPs contributed greatly in establishing the amido bonds within the composite. Transmission electron microscopy (TEM) and UV-visible spectroscopy were also used to characterize the PEI-AuNP-hemin catalyst. PEI-AuNP-hemin exhibited intrinsic peroxidase-like catalytic activities. The PEI-AuNP-hemin deposited on a glass carbon electrode had strong sensing for H2O2 with a well-defined linear relationship between the amperometric response and H2O2 concentration in the range from 1 μM to 0.25 mM. The detection limit was 0.247 nM with a high sensitivity of 0.347 mA mM(-1) cm(-2). The peroxidase-like catalytic activity of PEI-AuNP-hemin is discussed in relation to its microstructure. The study suggests that PEI-AuNP-hemin may have promising application prospects in biocatalysis and bioelectronics.

Modeling effects of initial dislocation microstructure on the yield strength in FCC single crystal Cu with dislocation dynamics

Three dimensional dislocation dynamics (3D-DD) method was used to study how initial dislocation microstructure, with varying dislocation density, length and distribution, affects the yield strength in face-centered cubic (FCC) single crystal Cu. Initial dislocations are generated for three average lengths for each one of the seven dislocation densities ranging from 0.1–5×1012m/m3.They are randomly distributed on slip planes. The uniaxial tension simulation results for two crystallographic loading orientations, [100] and [111], all show that the yield strength has a well-defined linear relationship with the average length of these dislocations, except for very low dislocation densities where small number of dislocations lead to a stochastic behavior. This indicates that dislocation-density based crystal plasticity formulations, including the square-root relationship between flow stress and dislocation density, only work when dislocation densities/numbers are sufficiently large so that a statistically accurate description of the microstructure can be obtainable.

The Accuracy of Radar Estimates of Ice Terminal Fall Speed from Vertically Pointing Doppler Radar Measurements

AbstractDoppler radar measurements at different frequencies (50 and 2835 MHz) are used to characterize the terminal fall speed of hydrometeors and the vertical air motion in tropical ice clouds and to evaluate statistical methods for retrieving these two parameters using a single vertically pointing cloud radar. For the observed vertical air motions, it is found that the mean vertical air velocity in ice clouds is small on average, as is assumed in terminal fall speed retrieval methods. The mean vertical air motions are slightly negative (downdraft) between the melting layer (5-km height) and 6.3-km height, and positive (updraft) above this altitude, with two peaks of 6 and 7 cm s−1at 7.7- and 9.7-km height. For the retrieved hydrometeor terminal fall speeds, it is found that the variability of terminal fall speeds within narrow reflectivity ranges is typically within the acceptable uncertainties for using terminal fall speeds in ice cloud microphysical retrievals. This study also evaluates the performance of previously published statistical methods of separating terminal fall speed and vertical air velocity from vertically pointing Doppler radar measurements using the 50-/2835-MHz radar retrievals as a reference. It is found that the variability of the terminal fall speed–radar reflectivity relationship (Vt–Ze) is large in ice clouds and cannot be parameterized accurately with a single relationship. A well-defined linear relationship is found between the two coefficients of a power-lawVt–Zerelationship, but a more accurate microphysical retrieval is obtained using Doppler velocity measurements to better constrain theVt–Zerelationship for each cloud. When comparing the different statistical methods to the reference, the distribution of terminal fall speed residual is wide, with most residuals being in the ±30–40 cm s−1range about the mean. The typical mean residual ranged from 15 to 20 cm s−1, with different methods having mean residuals of &lt;10 cm s−1at some heights, but not at the same heights for all methods. The so-calledVt–Zetechnique was the most accurate above 9-km height, and the running-mean technique outperformed the other techniques below 9-km height. Sensitivity tests of the running-mean technique indicate that the 20-min average is the best trade-off for the type of ice clouds considered in this analysis. A new technique is proposed that incorporates simple averages of Doppler velocity for each (Ze,H) couple in a given cloud. This technique, referred to as DOP–Ze–H, was found to outperform the three other methods at most heights, with a mean terminal fall residual of &lt;10 cm s−1at all heights. This error magnitude is compatible with the use of such retrieved terminal fall speeds for the retrieval of microphysical properties.

Response of the coccolithophores Emiliania huxleyi and Coccolithus braarudii to changing seawater Mg 2+ and Ca 2+ concentrations: Mg/Ca, Sr/Ca ratios and δ 44/40Ca, δ 26/24Mg of coccolith calcite

Calcium and magnesium concentrations in seawater have varied over geological time scales. On short time scales, variations in the major ion composition of seawater influences coccolithophorid physiology and the chemistry of biogenically produced coccoliths. Validation of those changes via controlled laboratory experiments is a crucial step in applying coccolithophorid based paleoproxies for the reconstruction of past environmental conditions. Therefore, we examined the response of two species of coccolithophores, Emiliania huxleyi and Coccolithus braarudii, to changes in the seawater Mg/Ca ratio (≈0.5 to 10 mol/mol) by either manipulating the magnesium or calcium concentration under controlled laboratory conditions. Concurrently, seawater Sr/Ca ratios were also modified (≈2 to 40 mmol/mol), while keeping salinity constant at 35. The physiological response was monitored by measurements of the cell growth rate as well as the production rates of particulate inorganic and organic carbon, and chlorophyll a. Additionally, coccolithophorid calcite was analyzed for its elemental composition (Sr/Ca and Mg/Ca) as well as isotope fractionation of calcium and magnesium (Δ 44/40Ca and Δ 26/24Mg). Our results reveal that physiological rates were substantially influenced by changes in seawater calcium rather than magnesium concentration within the range estimated to have occurred over the past 250 million years when coccolithophores appear in the fossil record. All physiological rates of E. huxleyi decreased at a calcium concentration above 25 mmol L −1, whereas C. braarudii displayed a higher tolerance to increased seawater calcium concentrations. Partition coefficient of Sr was calculated as 0.36 ± 0.04 (±2 σ) independent of species. Partition coefficient of Mg 2+ increased with increasing seawater Ca 2+ concentrations in both coccolithophore species. Calcium isotope fractionation was constant at 1.1 ± 0.1‰ (±2 σ) and not altered by changes in seawater Mg/Ca ratio. There is a well-defined inverse linear relationship between calcium isotope fractionation and partition coefficient of Sr 2+ in all experiments, suggesting similar controls on both proxies in the investigated species. Magnesium isotope ratios were relatively stable for seawater Mg/Ca ratios ranging from 1 to 5, with a higher degree of fractionation in Emiliania huxleyi (by ≈0.2‰ in Δ 26/24Mg). Although Mg/Ca ratios in the calcite of coccolithophores and foraminifera are similar, the former have considerably higher Δ 26/24Mg (by >+3‰), presumably due to differences in calcification mechanisms between the two taxa. These observations suggest, a physiological control over magnesium elemental and isotopic fractionation during the process of calcification in coccolithophores.

Controls on calcium isotope fractionation in cultured planktic foraminifera, Globigerinoides ruber and Globigerinella siphonifera

Specimens of two species of planktic foraminifera, Globigerinoides ruber and Globigerinella siphonifera, were grown under controlled laboratory conditions at a range of temperatures (18–31 °C), salinities (32–44 psu) and pH levels (7.9–8.4). The shells were examined for their calcium isotope compositions (δ 44/40Ca) and strontium to calcium ratios (Sr/Ca) using Thermal Ionization Mass Spectrometry and Inductively Coupled Plasma Mass Spectrometry. Although the total variation in δ 44/40Ca (∼0.3‰) in the studied species is on the same order as the external reproducibility, the data set reveals some apparent trends that are controlled by more than one environmental parameter. There is a well-defined inverse linear relationship between δ 44/40Ca and Sr/Ca in all experiments, suggesting similar controls on these proxies in foraminiferal calcite independent of species. Analogous to recent results from inorganically precipitated calcite, we suggest that Ca isotope fractionation and Sr partitioning in planktic foraminifera are mainly controlled by precipitation kinetics. This postulation provides us with a unique tool to calculate precipitation rates and draws support from the observation that Sr/Ca ratios are positively correlated with average growth rates. At 25 °C water temperature, precipitation rates in G. siphonifera and G. ruber are calculated to be on the order of 2000 and 3000 μmol/m 2/h, respectively. The lower δ 44/40Ca observed at ⩾29 °C in both species is consistent with increased precipitation rates at high water temperatures. Salinity response of δ 44/40Ca (and Sr/Ca) in G. siphonifera implies that this species has the highest precipitation rates at the salinity of its natural habitat, whereas increasing salinities appear to trigger higher precipitation rates in G. ruber. Isotope effects that cannot be explained by precipitation rate in planktic foraminifera can be explained by a biological control, related to a vacuolar pathway for supply of ions during biomineralization and a pH regulation mechanism in these vacuoles. In case of an additional pathway via cross-membrane transport, supplying light Ca for calcification, the δ 44/40Ca of the reservoir is constrained as −0.2‰ relative to seawater. Using a Rayleigh distillation model, we calculate that calcification occurs in a semi-open system, where less than half of the Ca supplied by vacuolization is utilized for calcite precipitation. Our findings are relevant for interpreting paleo-proxy data on δ 44/40Ca and Sr/Ca in foraminifera as well as understanding their biomineralization processes.

Grazing effects on seasonal dynamics and interannual variabilities of spectral reflectance in semi-arid grassland in Inner Mongolia

Detecting the influences of land management on seasonal dynamics and interannual variabilities of grassland surface reflectance is of scientific and practical importance as it can help to monitor grazing effects on the grassland ecosystem. We conducted spectral reflectance measurements at five differently grazed sites in Inner Mongolia, China, during the growing seasons of 2005 and 2006 using a portable, highly resolving spectrometer. Through analyses of the measured surface reflectance spectra and the derived visible albedo and NDVI, we found that grazing influences the reflectance spectrum shape and affects the visible albedo and NDVI seasonal pattern; visible albedo and NDVI of grazed sites are more sensitive to precipitation than that of ungrazed sites. In addition, we observed a well-defined linear relationship between total shortwave and visible (PAR) albedo, with R = 0.83 and R = 0.94 for 2005 and 2006, respectively, and between NDVI and total shortwave albedo with R = −0.92. Thus, NDVI spectrometer measurements and total shortwave albedo pyranometer measurements are interchangeable when addressing different grazing intensities.

Magnetostructural coupling and magnetocaloric effect in Ni–Mn–In

Magnetic-field-induced martensitic phase transition and the concomitant change of volume are investigated in Ni–Mn–In alloy. A well-defined linear relationship is found between the quantity characterizing magnetic degree of freedom and the thermal expansion on behalf of structural degree of freedom, which demonstrates the magnetostructural coupling. Within the exchange-inversion model, such a linear relationship is theoretically derived and the magnetostructural correlation is elucidated. The lattice-entropy change contributes about one half of the total entropy change, suggesting that the magnetostructural coupling plays an important role in the magnetocaloric effect of Ni–Mn–In alloy.

Evaluation of Semicircular Bending Test for Determining Tensile Strength and Stiffness Modulus of Asphalt Mixtures

Abstract The semicircular bending (SCB) test has been shown to possess several advantages over other tests in characterizing asphalt mixtures in previous studies. This research study evaluates the SCB test for determining the tensile strength and stiffness modulus of the paving material with numerical simulation and laboratory experimentation. An analytical model describing the tensile stress at the middle point of the lower surface of the specimen in the SCB test was developed based on the plane assumption in mechanics of materials. Analysis using the finite element method indicated that the error induced by the model was within 2 %. Laboratory experiment carried out on three types of asphalt mixtures at various temperatures showed that the strength of the material by the SCB test was nearly 50 % higher on average than that by the flexural beam bending (FBB) test due to such factors as complexities in stress and strain states as well as nonlinearity and viscoelasticity of the material. Laboratory experiment also showed that the stiffness moduli for 10–40 % of maximum load from the FBB test and from the SCB test were in a well-defined linear relationship with differences less than 10 %. In addition, based on finite element analysis, a practical approach for determining stiffness modulus of asphalt mixtures using deflection at the middle point of the lower surface of the specimen in the SCB test was established.