Temperature-sensitive Materials Research Articles

Experimental Study of Stress and Deformation of Reclaimed Asphalt Concrete at Different Temperatures.

Asphalt concrete has been used as a material for dam core walls because of its impermeability, durability and reliability. Firstly, asphalt is a temperature-sensitive material, and many of its characteristics are related to temperature. Secondly, because of the increasing construction height of the dam, the pressure on the asphalt concrete core wall is also great. Finally, for the purpose of resource utilization, it is necessary to verify whether the reclaimed asphalt concrete can be used in dam construction. Therefore, it is necessary to study the stress and deformation characteristics of recycled asphalt concrete under different temperatures and confining pressures. In this study, three groups of triaxial tests of reclaimed asphalt concrete were carried out for the first time in a new temperature-controlled room. Duncan Zhang's E-v model was used to fit the test results. The results show that the stress-strain curves of reclaimed asphalt concrete show softening characteristics at low temperatures and low confining pressure. It evolves to a hardening type with the increase in temperature and confining pressure. The bulk curve is first contracts but is followed by dilatancy. The dilatancy characteristics become more obvious at low temperatures and low confining pressure. With the increase in temperature and confining pressure, the dilatancy characteristics will weaken. Duncan Zhang's E-v model has a good fitting effect on the stress-strain relationship but a poor fitting effect on the volumetric curve. The research of this paper can better combine the utilization of waste resources with engineering and achieve the aim of resource-saving and waste utilization under the premise of ensuring the safety of the engineering.

Coaxial dual-core dispersion compensation photonic crystal fiber with wavelength-tunable ultrahigh negative dispersion

A coaxial dual-core wavelength-tunable dispersion compensation photonic crystal fiber (WT-DC-PCF) is designed in this paper. The tunable range of 1512–1587 nm with an ultrahigh negative dispersion of − 27315.76 p s / ( n m ⋅ k m ) at 1550 nm has been obtained simultaneously by filling the temperature-sensitive material into the air holes of the WT-DC-PCF. The full width at half-maximum is up to 12.4 nm, and a low confinement loss is always maintained. In addition, the phase-matching wavelength is basically linear with the temperature, which can be accurately adjusted to 1550 nm. Therefore, the proposed WT-DC-PCF is able to be used in achieving complete dispersion compensation in communication systems.

High-Sensitivity Temperature Sensor Based on the Perfect Metamaterial Absorber in the Terahertz Band

In this study, a perfect metamaterial absorber (PMMA) based on an indium antimonide temperature-sensitive material is designed and investigated in the terahertz region. We demonstrate that it is an ideal perfect narrow-band absorber with polarization-insensitive and wide-angle absorption properties. Numerical simulation results show that the proposed PMMA can be operated as a temperature sensor with a sensitivity of 21.9 GHz/K. A graphene layer was added to the PMMA structure to improve the sensitivity, and the temperature sensitivity was increased to 24.4 GHz/K. Owing to its excellent performance, the proposed PMMA can be applied in thermal sensing, detection, and switching.

Refractive Index and Temperature Sensing System With High Sensitivity and Large Measurement Range Using an Optical Fiber

In this article, a temperature and refractive index sensing probe based on a photonic crystal fiber (PCF) with a silver film coating is proposed. We suggested a simple method for coating silver films, and a silver film was coated on the periphery of the PCF that solves the previous difficulties of coating metal film inside the air holes or polishing a flat surface. The sensing probe has achieved dual-parameter sensing of refractive index and temperature by employing polydimethylsiloxane (PDMS) as the temperature-sensitive material. The results of the experiment demonstrated that the wide measurement range and high sensitivity of the sensing probe. It has a refractive index sensitivity of 3341.65 nm/unit of refractive index (RIU) in the range of 1.333–1.3953 and a temperature sensitivity of 2.02 nm/°C in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50-100\,\,^{\circ }\text{C}$ </tex-math></inline-formula> . The features of the suggested sensing probe, including its simple structure and ease of production, indicate the potential application in the field of biochemical sensing.

A boundary value problem of heat transfer within DBD-based plasma jet setups.

We claim an analytical solution for the thermal boundary value problem that arises in DBD-based plasma jet systems as a preliminary and consistent approach to a simplified geometry. This approach involves the outline of a coaxial plasma jet reactor and the consideration of the heat transfer to the reactor solids, namely, the dielectric barrier and the grounded electrode. The non-homogeneous initial and boundary value thermal problem is solved analytically, while a simple cut-off technique is applied to deal with the appearance of infinite series relationships, being the outcome of merging dual expressions. The results are also implemented numerically, supporting the analytical solution, while a Finite Integration Technique (FIT) is used for the validation. Both the analytical and numerical data reveal the temperature pattern at the cross-section of the solids in perfect agreement. This analytical approach could be of importance for the optimization of plasma jet systems employed in tailored applications where temperature-sensitive materials are involved, like in plasma biomedicine.

Numerical and Experimental Study on Axial Feed Skew Rolling of Small-Diameter GH4169 Alloy Bars

This study relates to an innovative method for forming small-diameter GH4169 superalloy bars by Axial Feed Skew Rolling (AFSR). The finite element (FE) model was established to reveal the deformation characteristics and rolling force parameters of GH4169 superalloy bar in AFSR process. The distribution of stress field reveals that in the deformation area, the stress state in the center of the workpiece is radial compression, axial and tangential tension. In the deformation area, the core temperature of the workpiece rises due to plastic deformation, but after leaving the deformation area, the temperature of workpiece decreases significantly. Therefore, for small-diameter long bars, especially temperature-sensitive materials, auxiliary heating equipment is required when using AFSR technology. Furthermore, the roller with clamping sections was designed, and the rolling experiments were carried out on a double-rotating-arm skew mill. The rolled pieces obtained have no helical grooves on the surface, and the diameter deviations are less than 0.1 mm. The actual rolling process is stable and highly consistent with the FE simulation, which verifies the reliability of the FE model and the feasibility of forming superalloy bars by the AFSR method.

Temperature sensing of Sr3Y2Ge3O12:Bi3+,Sm3+ garnet phosphors with tunable sensitivity.

In this study, a novel temperature-sensitive material, Sr3Y2Ge3O12:Bi3+,Sm3+ phosphor, was successfully synthesized by a solid-state reaction method. Under 376 nm light excitation, the as-prepared phosphor presents both blue emissions of Bi3+ and orange red emissions of Sm3+ due to energy transfer from Bi3+ to Sm3+. Owing to the significant difference in thermal quenching properties and the distinguishable emission between Bi3+ and Sm3+ ions, the temperature sensing performance of the prepared phosphor was evaluated by measuring the fluorescence intensity ratio (FIR) of Sm3+versus Bi3+. More importantly, for the first time, it was found that the absolute and relative sensitivities of Sr3Y2Ge3O12:Bi3+,Sm3+ could be tuned by changing the concentration of activators to determine the optimal temperature measurement conditions, which opened up the possibility of improving the performance of fluorescence temperature sensing materials.

Temperature Sensing Characteristics of Two Fundamental Solitons in a Glycerin-Filled Microstructured Optical Fiber

In this paper, the temperature sensing characteristics of two fundamental solitons in a glycerin-filled six-hole microstructured optical fiber (MOF) were systematically exploited through experiment and simulation. The six-hole MOF has a large duty cycle, which can increase the space to fill the temperature-sensitive material glycerin for improving the temperature sensing sensitivity. By detecting the center wavelength shift of 3dB bandwidth of two fundamental solitons at 1050 nm, 390 mW, a maximum sensitivity of -0.601 nm/ °C was obtained based on the first fundamental soliton and -0.598 nm/ °C was obtained based on the second. Simulation results combined with the experimental results showed that the higher the average pump power, the higher the temperature sensitivity, and the temperature sensitivity of the first was slightly higher than that of the second. The difference in sensing characteristics between the two fundamental solitons discovered in this study could provide a novel solution to solve the cross-sensitivity of dual-parameter sensing. To the best of our knowledge, this is the first research about utilizing two fundamental solitons for temperature sensing, which broadens the boundary of the nonlinear-based sensors, and has promising prospects in the fields of national defense security, disease monitoring, agriculture production, etc.

Highly Efficient D-type Photonic Crystal Fiber Surface Plasmon Resonance Sensor for Same Space–Time Temperature and Refractive Index Detection

In order to realize temperature and refractive index (RI) detection of the analyte in the same space–time, a dual parameter detection photonic crystal fiber (PCF) optical sensor is proposed in this paper. Meanwhile, it can effectively avoid the interference of analyte temperature with RI detection. Furthermore, a dual polished D-type structure is designed to provide mutually independent detection channels for temperature and RI, respectively. In addition, silver is used as the metal layer material, and polydimethylsiloxane (PDMS) and titanium dioxide (TiO2) are used as the temperature-sensitive materials and RI-sensitive materials, respectively. This structure design enables the two detection results to be output in parallel without interfering with each other. The proposed optical fiber sensor has a wide detection range and good detection performance. The temperature detection range can be as wide as −60 to 100°C, and the RI detection range is 1.30–1.40. The best temperature resolution can be 1.42 × 10−2 RIU, and the temperature wavelength sensitivity is 0.7 nm/°C. While the RI wavelength sensitivity is up to 1.25 × 104 nm/RIU, and the wavelength resolution is 8 × 10− 6 RIU. The detailed fabrication process of the sensor is given in this paper, as well as the practical application scenarios. Therefore, the optical fiber sensor proposed in this paper has research significance for the development of dual parameter detection optical fiber sensors.

Study on Temperature Correction of Asphalt Pavement Deflection Based on the Deflection Change Rate

The pavement deflection measured by falling weight deflectometer (FWD) detection equipment can be used to determine the bearing capacity of a pavement structure through modulus backcalculation to provide suggestions for pavement structure maintenance. However, because asphalt mixtures are temperature-sensitive materials, they are greatly affected by temperature, and changes in temperature can cause their mechanical properties to vary and affect the structural bearing capacity. Therefore, this paper conducts a pavement deflection test on an in-service highway asphalt pavement at different temperatures in different seasons. The representative temperature of the asphalt layer was determined through comparative analysis. The temperature’s effective influence distance on the deflection basin was found, and a more suitable temperature correction model for the deflection basin of asphalt pavement was established. The results showed that the temperature at the middle layer depth of the asphalt layer is more suitable as the representative temperature of the asphalt layer. The effective influence range of temperature on the deflection basin is 90 cm. The deflection change rate before and after the temperature correction at a radial distance of 20 cm is more appropriate for the temperature correction of the deflection basin.

Photostable temperature sensitive luminescent materials based on polystyrene doped by an anisometric Europium(III) complex

A polystyrene polymer and an Eu(III) anisometric complex were used to produce films with various luminophore contents. Due to its structural features (anisotropic form and long hydrocarbon substituents at molecular ends), the luminophore used in this research is an amorphous powder that is highly soluble in organic polar and nonpolar solvents as well as miscible with polymers. These features allow this luminophore to be incorporated into polymer networks without losing its luminescence efficiency due to self-quenching. The effect of temperature on the lifetime and luminescence intensity of the Eu(III) films was studied. It was found that their maximum luminescence intensity and lifetime are 2 times higher than those of other lanthanide-containing β-diketonate thermosensors. The photostability of the films was studied. It was demonstrated that the films can be used as materials for fluorescent thermometers that operate in the temperature range of 303–363 K.

On the availability bias in narwhal abundance estimates

Abundance estimation of narwhals is usually done with either visual or photographic aerial surveys. The basic estimation for both methods is detection of whales at the surface, and to obtain fully corrected abundance estimates, the at-surface detections need to be corrected for the proportion of whales that, at any given time, is available to be detected at the surface. The surfacing time or ‘availability correction factor’ is obtained from whales instrumented with dive recorders, that either relay concatenated information on the proportion of time spent at different depth intervals to satellites, or from recovered instruments that collect complete dive profiles, measured at high frequency. Concatenated data binned in depth histograms from Satellite-Linked-Time-Depth-Recorders (SLTDR) falls in two categories, where those that correct the zero depth values with information from the saltwater switch provide larger and apparently more accurate surfacing times, than those collected from instruments that does not correct the zero depth readings. The erroneous detection of near-surface pressure values is likely due to slow response of pressure transducers made from temperature sensitive materials. The high frequency sampling from AcousondeTM recorders documents erroneous surface detections, and adjustments of the dive profiles are needed to obtain realistic near-surface values. Any reconstruction of dive profiles and near-surface values apparently involves some level of corrections and it is recommended, for development of availability correction factors for aerial surveys, that data from zero-adjusted SLTDRs or TDR instruments are used. The mean estimate of surface time from 7 SLTDRs was 29% (CV=0.05). One SLTDR, with steel pressure transducer and zero-adjustments, that was retrieved from the whale, provided a particular long-record (83 days) of reliable high-resolution data. The surface time for this sample was 31%, when calculated as the sum of all depth readings at or above 2 m. The mean of 144 hourly depth readings during 06:00-18:00, and including dives above 3m, was 27.36% (CV=0.8) for 12 days overlapping with the usual timing of aerial surveys. Accurate estimation of smaller depth bins (e.g. 0-1 m) should, even with high resolution instruments, be used with caution when estimating availability bias.

Anti-crosstalk optical fiber sensor based on polydimethyl siloxane fluid cavity and graphene oxide film

An integrated optical fiber sensor with high sensitivity and extremely low crosstalk was theoretically and experimentally demonstrated for sensing temperature and pressure. Integration of dual pressure/temperature sensitive materials on a section of hollow-core fiber (HCF) by core-offset part filling technology and dipping technology. Through the movable polydimethyl siloxane fluid (PSF)-air surface and the short cavity length of the PSF, the sensitivity of the PSF as a temperature-sensitive material reaches to 2.15 nm/°C, but it presents the immunity of wavelength to pressure. The sensitivity of graphene oxide (GO)-based air cavity as a pressure-sensitive material can reach −748.15 nm/Mpa with the GO film thickness of 713 nm. In addition, experimental results show that the cross-sensitivity between temperature and pressure are 0 °C/Mpa and 0.000318 Mpa/°C. Thus, the proposed sensor shows a strong capability of dual-parameter discriminative proficiency, anti-crosstalk and simultaneous measurement of temperature and pressure. Such a compact, robust and low-cost sensor, is significant for the applications of exploitation of marine resource and well and reservoir down-hole operations.

Dynamically Switchable Sub-THz Absorber Using VO2 Metamaterial Suitable in Optoelectronic Applications

Temperature-sensitive materials are known as phase change materials (PCMs) which has transition between two different states. Dynamically tunable devices can be designed utilizing these materials. Vanadium dioxide (VO2) considered as a PCM material which transits from the insulator state to the metal one by increasing the temperature. VO2 has recently been utilized to design tunable absorbers. In this article, we presented a dual-band absorber structure design which consist of double arrays of VO2 ring-based placed on top of a dielectric buffer/spacer terminated with a conducting layer acting as a back reflector. Each ring acts as a resonator producing a surface plasmon resonance (SPR). Having a proper unit cell design with an appropriate dimension, a dual-band absorber with an absorption amplitude above 95% (ON state) can be achieved at terahertz (THz) frequency range in the metallic state; whereas the absorption value is 0.6% (OFF state) in the insulator state of VO2. Therefore, the proposed structure design has the possibility to switch between these two ON/OFF states by changing the material’s temperature. The interference theory and the equivalent circuit model are investigated to verify the achieved result using high-frequency structure simulator (HFSS) software which works based on finite element method (FEM). This structure has the potential optoelectronic applications such as refractive index (RI) optical sensing and biomedical detection, photonics detectors, and optical storage applications.

선택적 레이저 소결을 이용한 유연인쇄전자소자 제작

It is necessary to develop a low temperature process that can deposit and pattern metal on a heat sensitive substrate because most flexible printed electronics use high temperature sensitive materials such as plastic. The most commonly used photolithography process is not suitable for flexible printed electronics because the high temperature thermal treatment process and chemicals are not compatible with plastic. Recently research has been actively conducted on a method of minimizing thermal damage to plastic and high-resolution metal patterning by using selective laser sintering after forming a liquid metal nanoparticle thin film without using existing photolithography and vacuum deposition. In this review paper, we explore flexible printed electronics such as flexible thin film transistors and flexible transparent conductors using selective laser sintering of nanomaterials and discuss future development directions.

Ag-(In-Bi) Solid–Liquid Interdiffusion Bonding

Solid–liquid interdiffusion is a metallurgical bonding technique, suitable for assembly of temperature sensitive materials. We identify Ag-(In-Bi) as meeting the low-temperature bonding requirements, theoretically as low as 73°C. This work focuses on understanding the bonding process and the interactions between the metal elements. Ag-(In-Bi) was bonded using an eutectic In-Bi foil at both 150°C and 180°C. The resulting bondlines were layered as Ag/Ag9In4/AgIn2/In-Bi compounds/AgIn2/Ag9In4/Ag. At some sections the phase growth of AgIn2 or Ag9In4 bridged the bond. Because of this bridging of γ-Ag9In4, temperature stability of ~480–570°C, is readily possible. The majority of the remaining Bi was located within large pockets near the middle of the bondline, and the minority as precipitates in protruding arms. Mechanisms for these Bi precipitates and intermetallic arm growth are discussed, and the evidence indicates that dissolution and surface planarity play important roles in their formation.

Accelerated water removal from frozen thin films containing bacteria

Freeze-drying, or lyophilization, is widely used to produce pharmaceutical solids that contain temperature-sensitive materials. Herein, using Escherichia coli as a model live organism, whose viability in dry powders is highly sensitive to the water content in the powders, we demonstrated that the drying rate from the frozen thin films generated by thin-film freezing (TFF) is significantly faster than from the bulk frozen solids in conventional shelf freeze-drying. This is likely because the loosely stacked frozen thin films provided a larger solid-air interface and the low thickness of the thin films provided a low mass transfer resistance. The highly porous microstructure and high specific surface area of the thin-film freeze-dried powders may also be related to the faster drying observed. Moreover, we demonstrated that TFF can be applied to produce dry powders of E. coli, a Gram-negative bacterium, or Lactobacillus acidophilus, a Gram-positive bacterium, with minimum bacterial viability loss (i.e., within one log reduction). It is concluded that the TFF technology is promising in accelerating water removal from frozen samples.

Dielectric properties of asphalt mastics considering temperature effect

Ground Penetrating Radar (GPR) evaluates the quality of asphalt pavements and identifies different distresses based on the difference in the dielectric properties of asphalt pavement materials at different positions of the asphalt pavement structural layers. Asphalt mastic is an important component of asphalt mixture, and the performance of the mortar considerably affects the macro dielectric properties of the mixture. Hence, investigating the dielectric properties of asphalt mastic is crucial in understanding the overall dielectric properties of asphalt mixture. As a temperature-sensitive material, asphalt mastic exhibits temperature-dependent variations in its dielectric properties. Thus, this study conducted tests to investigate the dielectric properties of asphalt mastic at different temperatures and evaluated classical dielectric models. The results showed that the classical models did not adequately predict the dielectric properties of asphalt mastic because classical models ignore the effect of temperature on the dielectric properties of asphalt mastic. Micro test results show that temperature will affect the surface and internal structure of asphalt mastic, and then affect the performance of asphalt mixture.Through model verification, it is found that the model has a high calculation accuracy, which is more than 90%. This can quantify the influence of temperature field on the dielectric properties of asphalt mastic, and also pave the way for the next research on the temperature effect on the dielectric properties of asphalt mixture. This is because the proposed model not only considers the dielectric constant of asphalt mastic components, but also considers the influence of temperature on the dielectric constant of components. These research results not only have important academic value for enriching and developing the basic theory of GPR, but also can provide guidance for selecting the best filler-asphalt ratio in the actual field.

Organic Single Crystal/Polymer Hybrid Actuator with Waveguide, Low Temperature, and Humidity Actuation Properties

Organic single crystal/polymer hybrid actuators that can be applied in extreme conditions such as polar regions and space are extremely important and rare. Herein, we report an extremely simple but efficient strategy to fabricate hybrid organic crystalline materials with low-temperature, humidity actuation, and waveguide properties. First, needle-like crystals composed of 10-(trifluoromethyl)anthracene-9-carbonitrile (TFMAC) exhibited excellent elastic properties in the temperature range of 77–423 K. Second, we prepared a crystal/polymer hybrid by coating a layer of polyvinyl alcohol (PVA) polymer on the crystal surface. Fortunately, the flexible hybrids had wet and low-temperature actuation properties. The mechanical claws made of hybrids could transport objects at low temperature, showing excellent actuation behavior. Meanwhile, organic crystals and hybrids exhibited excellent optical waveguide properties, with optical loss coefficients as low as 0.29–0.45 dB mm–1 before and after bending. This article has opened up new ideas for the design and fabrication of temperature-sensitive flexible composite functional waveguide materials.

A Surface Plasmon Resonance-Based Photonic Crystal Fiber Sensor for Simultaneously Measuring the Refractive Index and Temperature.

In this paper, a surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) sensor is proposed for simultaneously measuring the refractive index (RI) and temperature. In the design, the central air hole and external surface of the proposed PCF are coated with gold films, and an air hole is filled with the temperature-sensitive material (TSM). By introducing the inner and outer gold films and TSM, the RI and temperature can be measured simultaneously at different wavelength regions. The simulation results show that the average wavelength sensitivities of the proposed SPR-based PCF sensor can reach 4520 nm/RIU and 4.83 nm/°C in the RI range of 1.35~1.40 and a temperature range of 20~60 °C, respectively. Moreover, because of using the different wavelength regions for sensing, the RI and temperature detections of the proposed SPR-based PCF sensor can be achieved independently. It is believed that the proposed SPR-based PCF RI and temperature sensor has important applications in biomedicine and in environmental science.