Value Of Critical Temperature Research Articles

Design analysis of a steel industrial building with wide openings exposed to fire

In order to design a fire-resistant steel structure, the change in the physical and mechanical properties of the steel at high temperatures must be known. As the temperature of steel structural elements increases during fire, their strength decreases considerably. After a certain temperature, these strength drops reach critical levels. Therefore, collapses and various deformations (buckling, arching, etc.) occur. To prevent these collapses during the fire, various fire protection materials must be applied to the structural members such as column and beam. Columns are the most critical structural elements in a steel bearing system. While the possible collapse of the columns may cause the collapse of the whole structure, the beams alone may not cause the collapse of the structure, and the column-beam junctions directly affect the spread of fire. Since there will be many openings and gaps in industrial buildings, the spread and growth of a possible fire becomes very serious. Special fire protection measures are therefore required. In this study, the behavior of a steel industrial structure designed and designed under the influence of Standard Fire (ISO 834) was investigated, the distribution of the temperatures in the structural elements was determined, the required fire protection material was selected, and both protected and unprotected steel temperatures were determined. This design against fire is designed to provide fire resistance for 1 hour (60 min) for this structure. During this period, the type and optimum thickness of the protection material to be applied before reaching the critical temperature values for which the strength of the steel material would lose and would be damaged and compared with the temperatures that would occur in the structural elements without applying fire protection. According to the findings of the study, it was concluded that 25 mm drywall box protection material should be applied on the inner columns and 20 mm on the edge columns and 15 mm on the corner columns. In addition to this, it was concluded that spray beams (intumescent coating) of different thicknesses between 15-20 mm were applied to the beams depending on the location and the load to be affected and the type of joint. After these applied passive fire protection materials, the temperatures obtained in the structural elements reached to 500-550 as a result of 1-hour fire design. These temperatures are acceptable temperature values given the strength drop in critical temperature ranges for steel under the 1-hour fire condition.

Amphiphilic copolymer aqueous solutions with cholinium ionic liquids as adjuvants: New insights into determination of binodal curves and phase-separation mechanisms

Aqueous two-phase micellar systems (ATPMS) are more than simple amphiphilic copolymer or surfactant aqueous solutions since due to the formation of biphasic regimes, at certain temperatures, these can be successfully used for the separation, encapsulation, and formulation of several bio-based compounds. The recent use of ionic liquids (ILs) as adjuvants in the formation of ATPMS have enlarged its “working window”, but the measurement of respective binodal curves is still very empiric and dependent of operator accuracy through the visual determination of cloud-point temperature. In this work, the range of ATPMS using ILs as adjuvants was extended, providing more insights about their phase formation mechanisms, as well as into determination of cloud-point values of the lower critical solution temperature (LCST)-type demixing transition by using the new temperature modulated optical refractometry approach. The binodal curves of ATPMS composed of Pluronic® L35/PBS buffer at pH 7.4 + cholinium ILs were determined, by using two different methods, i.e.: cloud-point temperature (TCP) visual determination versus temperature modulated optical refractometry (TMOR). TMOR method was more sensitive to the determination of biphasic transition, particularly, in highly diluted solutions (< 3.0 wt% of Pluronic L35). The results also established that the addition of cholinium ILs decreased significantly the phase separation temperatures of Pluronic L35/PBS, with an increase of biphasic region (viz. lower of TCP values) as a function of the relative hydrophobicity of the IL anion, i.e.: [Hex]− > [But]− > [Pro]− > [Ac]− > Cl−. The use of cholinium ILs as adjuvants is particularly important to provide mild conditions for ATPMS-based separation and encapsulation strategies, while TMOR-based methods allow an improvement of phase separation determination accuracy.

Improvement of the Assessment Method for Fire Resistance of Steel Structures in the Temperature Regime of Fire under Realistic Conditions

There was researched the influence of fire temperature regimes, obtained by the proposed mathematical models, on the mechanical characteristics of metal structures. As a result, the identified patterns of the influence of the parameters of the premises with fires are shown as the slit coefficient decreases and the fire load density increases, the actual limit of fire resistance begins to decrease, as well as at values of fire load density less than 600 [MJ/m2], there is an area where the occurrence of a boundary state is not observed and Nomograms for determining the limit of fire resistance for steel structures at standard values of critical temperature were constructed and an appropriate method was developed.

Effect of CeO&lt;sub&gt;2&lt;/sub&gt; Nanoparticle on the Structural and Electrical Properties of BSCCO-2223 High Temperature Superconductor

A study of the effects of Cerium oxide nanoparticle doped with BSCCO-2223 on the microstructure and superconducting properties was carried out. All samples were synthesized using solid state reaction method. Ce concentration is varied from x = 0.0 up to 0.1 in a general stoichiometry of Bi1.6Pb0.4Sr2Ca1-xCexCu3Oy. The samples were characterized structurally and electrically by X-Ray Diffraction (XRD) and four-point probe method respectively. XRD analysis shows that both (Bi,Pb)-2212 and (Bi,Pb)-2223 phases coexist in the samples having tetragonal crystal structure but changed to orthorhombic when x=0.10. The values of critical transition temperature, TC and critical current density, JC of the samples decreased with the increase in Ce concentration. The possible reasons for the observed degradation in superconducting and structural properties of Bi-2223 due to Ce nanoparticles addition were discussed.

Nanocomposite smart hydrogel based on sepiolite nanochannels/N-isopropyl acrylamide/itaconic acid/acrylamide for invertase immobilization

ABSTRACT Novel nanocomposite smart hydrogel (NSH) and smart hydrogel (SH) are prepared to be used as a support for invertase. Spectrophotometric and thermal analysis methods were used for the characterization. Lower critical solution temperature values of SH and NSH were found as 32.68°C and 30.44°C, respectively. From the pH-responsive swellings performed at three different temperatures, the inflection point values of NSH were found at higher pHs compared to SH. Invertase was immobilized onto SH and NSH (SH−I and NSH−I). The optimum pH and temperature values were found. Michaelis constant and maximum reaction rate were calculated. NSH−I showed excellent thermal, operational and pH stability.

Temperature Increase Research of Particles Formed by Ultrasonic Grinding of Spinach Leaves

The researchers chose spinach leaves as the research object for obtaining a natural dye based on chlorophyll because the vegetable is a food raw material rich in this pigment, and biologically active substances source with variety of its functional properties. To solve the problem of more complete chlorophyll extraction from crushed spinach leaves, they are to subject to a preliminary short-term soaking in a water/organic reagent emulsion under ultrasonic influence. Given that the water-based spinach suspension is thermolabile, a man must observe temperature restrictions, since when a certain critical temperature value is exceeded, the chlorophyll decomposition probability with its consumer properties loss is high. As it is practically impossible to determine the temperature inside a fine particle suspended in an aqueous emulsion experimentally, the authors considered to model internal and external heat transfer by solving the differential equation of heat energy transfer under appropriate boundary conditions using the numerical method of finite differences. The research determined structural-mechanical and thermophysical characteristics of crushed spinach leaves experimentally using the complex calculation method of thermophysical parameters based on the thermal inertia properties of a thermocouple. A man verified the solution adequacy by empirically determined suspension temperature after completion of the technological procedure. According to the developed algorithm, the authors compiled a program for the temperature fields evolution in the object of study considering the incident ultrasonic flow and an internal heat source with the new surface formation when grinding spinach particles in order to comply with thermal restrictions and maximize the quality parameters preservation. The article considers the rational duration of the ultrasonic grinding process without exceeding the recommended threshold temperatures.

Mathematical modelling and validation of the thermal buoyancy characteristics of a mixed mode natural convection solar crop dryer with back up heater

This paper presents the modelling and subsequent validation of the thermal buoyancy characteristics for an experimental mixed-mode natural convection solar crop dryer (MNCSCDBH) for three plenum inlet opening to vent outlet opening ratios of 1:1, 1:1.3 and 1:1.5 selected for the purpose of this study. The simulation follows the authors’ experimental study on the effect of varying the plenum inlet width and vent outlet width on thermal buoyancy performance of the MNCSCDBH for three different heating scenarios namely; solar heating, back up heating and hybrid heating. Mathematical models, capable of predicting the thermal buoyancy performance of the MNCSCDBH for the three selected heating modes were formulated by coupling energy balance equations on the components of the air-heater with energy balance for the air. The models were based on a one-dimensional steady-state operation of the dryer. A MATLAB code was developed and used to predict the performance of the dryer under no load conditions. The temperature predictions were observed to be accurate within 0.03% to 9.3% for solar heating mode, 0.20% to 7.49% for backup heating mode, and 0.03% to 12.8% for hybrid heating modes, respectively. Even though some discrepancies were found between the experimental performance indicators and their corresponding values predicted by the model as presented in this study, the code can be used in predicting the ventilation performance of the dryer under no load conditions with a general prediction to within 0.03% to 12.8% relative difference of the observed outlet velocity and critical system temperature values. The validation results show that the simulation code can serve as an effective tool for comparing and refining the designs of the MNCSCDBH for optimum drying performance.

Batch binding studies with thermo-responsive polymer grafted sepharose 6 fast flow sorbents under different temperature and protein loading conditions

This study has examined the batch binding behaviour of different thermo-responsive co-polymer grafted chromatographic materials under different temperature and protein loading conditions. The effect of molecular composition of poly(N-isopropylacrylamide) (PNIPAAm)-based co-polymers on the phase transition properties has been documented. Sixteen co-polymers of different compositions were synthesized by free radical polymerization methods. Most underwent relatively sharp phase transitions upon application of increasing temperature. However, the value of the lower critical solution temperature (LCST) varied due to differences in co-polymer compositions. In general, it was found that the LCST increased for co-polymers containing more hydrophilic moieties, but decreased for co-polymers with more hydrophobic moieties. Moreover, the LCST increased, together with increased width of the transition temperature, when highly branched monomeric moieties (i.e. N‑tert‑octyl groups) were present. When bulky side chains (octadecyl or triphenylmethyl groups) were located in the polymer structures the LCST transition was absent. Based on these findings, 6 thermo-responsive co-polymers of different compositions were individually immobilised onto cross-linked Sepharose 6 Fast Flow by a “grafting-from” method. Bovine holo-lactoferrin and bovine holo-transferrin at different concentrations in the range 1–100 mg/mL were then employed as target proteins to evaluate the adsorption behaviour under batch binding conditions with these different polymer grafted Sepharose 6 Fast Flow sorbents at two different temperatures. In general, all sorbents exhibited greater affinity and adsorption capacity for bovine holo-lactoferrin at 50 °C compared to 20 °C. In addition, the affinity and adsorption capacity of bovine holo-lactoferrin with positively charged copolymer grafted Sepharose 6 Fast Flow chromatographic sorbents at 20 °C and 50 °C were much lower than that found for negatively charged copolymer grafted Sepharose 6 Fast Flow sorbents, whilst the opposite trend was found with bovine holo-transferrin due to differences in the surface charge properties of these two proteins, indicative of different separation selectivity. Furthermore, the structure of the side chains present in the grafted copolymer structure was found to affect the adsorption performance of both proteins at 20 °C and 50 °C.

Superconductivity of alkali-metal intercalated BC2

The superconductivity of alkali-metal intercalated BC2, MxBC2 (M = Li, Na, and K; x = 0.5–1.5), has been studied using first-principles calculations. The calculated critical temperature (Tc) values are substantially high at x = 0.5 (49.8–57.1 K), which are higher than those for MgB2 and close to those predicted for LixByCz compounds. The Tc values at x = 1.5 are comparatively low (0.6–5.6 K) and close to those for graphite intercalation compounds. No superconductivity is observed at x = 1.0 for all alkali metals. An analysis of the electronic structures reveals that at x = 0.5, the state at the Fermi energy includes the σ bond character. In contrast, at x = 1.5, the state includes only π bonds comprising pz orbitals of B and C atoms. The σ bond character is essential for attaining high Tc values because the σ bond couples strongly with the bending-like phonon modes of the BC2 layer. However, the π bond couples weakly with the stretching-like phonon modes due to the small overlap of the pz orbitals, which results in a relatively low Tc for the material.

Quasi-steady characteristics of flowing propane/air mixture ignited by a heated surface

Quasi-steady behavior of a flowing propane/air mixture ignited by a surface heated at a constant power was investigated as a first step in assessing the physical risk of alternative clean energy. A series of experiments was carried out in which flowing propane was exposed to a heated surface at various supplied voltages and flow velocities. From the experimental results, the following findings were obtained: (1) ignition initiated from the bottom of the heated surface, and a flame first propagated on the downstream side of the heated surface; (2) the existence of the critical heat flux to ignite the flowing mixture was found, which was a major difference between ignition by a constant-temperature, hot surface and that by a constant-heat-flux, heated surface; (3) the limit of ignition temperature was expressed as a function of flow velocity, and the size of heated surface, yielding a curve which converges to a critical value of ignition temperature. The experimentally-measured dependence of the critical heat flux and ignition temperature on the flow velocity was consistent with the prediction of theoretical analysis conducted in this study.

Temperature influence on dynamic behavior of spacecraft waveguides

The lowest eigenfrequency and critical force are important parameters which defines structure behavior under dynamic loading. The paper describes the influence of temperature on the lowest eigenfrequency and critical force of a waveguide straight section in the spacecraft. The straight waveguide modeled according to the beam theory. It has been shown that the temperature change is equivalent an appearance and action of the axial force which makes the structure prestressed and significantly modifies its lowest eigenfrequency. An example of calculation of dependence of the waveguide straight section lowest eigenfrequency on temperature was considered, and it showed the existence of a critical temperature value, where the vibration frequency equals to zero. This critical temperature value corresponds to the loss of waveguide structure stability which is extremely undesirable and requires special methods to avoid such a situation. Stress state of waveguide in case of its loss of stability is also estimated.

Thermoresponsive Shape‐Memory Hydrogel Actuators Made by Phototriggered Click Chemistry

AbstractThis article describes the design and synthesis of a new series of hydrogel membranes composed of trialkyne derivatives of glycerol ethoxylate and bisphenol A diazide (BA‐diazide) or diazide‐terminated PEG600 monomer via a Cu(I)‐catalyzed photoclick reaction. The water‐swollen hydrogel membranes display thermoresponsive actuation and their lower critical solution temperature (LCST) values are determined by differential scanning calorimetry. Glycerol ethoxylate moiety serves as the thermoresponsive component and hydrophilic part, while the azide‐based component acts as the hydrophobic comonomer and most likely provides a critical hydrophobic/hydrophilic balance contributing also to the significant mechanical strength of the membranes. These hydrogels exhibit a reversible shape‐memory effect in response to temperature through a defined phase transition. The swelling and deswelling behavior of the membranes are systematically examined. Due to the click nature of the reaction, easy availability of azide and alkyne functional‐monomers, and the polymer architecture, the glass transition temperature (Tg) is easily controlled through monomer design and crosslink density by varying the feed ratio of different monomers. The mechanical properties of the membranes are studied by universal tensile testing measurements. Moreover, the hydrogels show the ability to absorb a dye and release it in a controlled manner by applying heat below and above the LCST.

Electrospun P(NVCL-co-MAA) nanofibers and their pH/temperature dual-response drug release profiles

In this work, pH/temperature dual-sensitive polymers of P(NVCL-co-MAA) with the increased low critical solution temperature (LCST) values of about 37 °C that differed from that of ~ 32 °C of pure poly(N-vinyl caprolactam) (PNVCL) were synthesized via radical polymerization. Then the nanofibers of P(NVCL-co-MAA) and its cospinned nanofibers with nifedipine (NIF) as drug model were fabricated by electrospinning method. Structures and the interactions within the components were detected by FT-IR, NMR, and XPS methods. The dual-responsive properties and the controlling release of the drug were investigated by water contact angle tests and in vitro drug release tested by UV-vis spectrophotometer. SEM was conducted to demonstrate the morphology of the nanofibers and the obvious improved stabilized morphology of the modified system within the aqueous media. The maintained morphology within the media and the obvious elongated releasing period of over 150 min at 37 °C and with pH of 1.99 both proved the promising prospects of the fabricated nanofibers as excellent carrier in drug delivery system.

Preparation and self-assembly of thermosensitive triblock copolymers with N-isopropylacrylamide and 3-methacryloxypropyltrimethoxysilane as monomers

Well-defined triblock copolymers poly(N-isopropylacrylamide)-b-poly(3-methacryloxypropyltrimethoxysilane)-b-poly(N-isopropylacrylamide) (PNIPAM-b-PMEMO-b-PNIPAM) with varying block ratios were successfully synthesized via reversible addition–fragmentation chain transfer polymerization. The amphiphilic triblock copolymers showed surfactant-like behavior in aqueous solution and could easily self-assemble into dendritic micelles with hydrophobic PMEMO as the core and hydrophilic PNIPAM as the shell when the copolymer concentration exceeded the critical micelle concentration (CMC). Transmittance measurements showed the triblock copolymers were thermosensitive, and it was worth noting that the lower critical solution temperature (LCST) values of copolymers exceeded pure PNIPAM to about 35.3 °C, which was very close to physiological temperature of human body. This was attributed to the effect of Si–O–CH3 hydrolysis in polymers. The effect of a series of inorganic salts on thermosensitivity of PNIPAM-b-PMEMO-b-PNIPAM was investigated, and our results suggested that the block copolymers maintained good thermosensitivity in all salt solutions. The LCST did not change significantly in different concentrations of NaCl, CaCl2 and MgCl2 solutions, which proved the polymer had good salt resistance. Dynamic light scattering experiments showed that the micelles were well dispersed at about 120 nm below LCST with a small polydispersity index. In addition, the drug-loading experiments of micelles showed high drug encapsulation efficiency indicating their potential as drug carriers.

Estimating the Threshold Effects of Climate on Dengue: A Case Study of Taiwan.

Climate change is regarded as one of the major factors enhancing the transmission intensity of dengue fever. In this study, we estimated the threshold effects of temperature on Aedes mosquito larval index as an early warning tool for dengue prevention. We also investigated the relationship between dengue vector index and dengue epidemics in Taiwan using weekly panel data for 17 counties from January 2012 to May 2019. To achieve our goals, we first applied the panel threshold regression technique to test for threshold effects and determine critical temperature values. Data were then further decomposed into different sets corresponding to different temperature regimes. Finally, negative binomial regression models were applied to assess the non-linear relationship between meteorological factors and Breteau index (BI). At the national level, we found that a 1°C temperature increase caused the expected value of BI to increase by 0.09 units when the temperature is less than 27.21 °C, and by 0.26 units when the temperature is greater than 27.21 °C. At the regional level, the dengue vector index was more sensitive to temperature changes because double threshold effects were found in the southern Taiwan model. For southern Taiwan, as the temperature increased by 1°C, the expected value of BI increased by 0.29, 0.63, and 1.49 units when the average temperature was less than 27.27 °C, between 27.27 and 30.17 °C, and higher than 30.17 °C, respectively. In addition, the effects of precipitation and relative humidity on BI became stronger when the average temperature exceeded the thresholds. Regarding the impacts of climate change on BI, our results showed that the potential effects on BI range from 3.5 to 54.42% under alternative temperature scenarios. By combining threshold regression techniques with count data regression models, this study provides evidence of threshold effects between climate factors and the dengue vector index. The proposed threshold of temperature could be incorporated into the implementation of public health measures and risk prediction to prevent and control dengue fever in the future.

In-flame spheroid formation from non-spherical slag particles – A numerical and experimental study

In order to identify the key factors for successful and efficient production, the formation of spherical particles from highly non-spherical coal slag grains was investigated within this work. The main focus was on precise drag and heat transfer calculations in order to obtain suitable criteria to predict the later product quality. State-of-the-art combustion, radiation and multiphase models in combination with specially adapted closure relations for drag and heat transfer were used for this purpose. The second objective was to investigate the relationship between particle temperature, viscosity, surface tension, shape and time required by the particles to obtain a smooth, round surface while passing through the burner chamber. In the first step, the process was investigated in experimental work. Slag particles were injected into an experimental furnace with a thermal input of 70 kW. The slag particles heated up which caused a reduction of slag viscosity by several orders of magnitude. While passing through the furnace, the sharp-edged powder grains transformed into smooth, highly spherical particles due to their surface tension. Numerical calculations were used to identify the main influence factors of in-flame spheroid formation. The effects of particle temperature, size, initial shape and residence time on the sphericity of the particle were studied using a Volume of Fluid (VOF) multiphase model and single-particle simulations which allowed calculations of the interface between an isothermal particle and the surrounding gas phase, as well as the interface deformation due to surface tension. The calculations have shown, that particles with volume-equivalent diameters in the range 420 µm-840 µm and an initial sphericity of 0.65 transform to spheroids in timescales in the order of 10−1 – 10° s when heated to temperatures above 1373 K. The critical particle temperature value of 1373 K was also confirmed by Euler-Lagrangian calculations of the reactive multiphase flow in the furnace. It has been shown that the particle peak temperature is a sufficient criterion for the formation of spheroids from highly non-spherical particles and that fluid temperature and particle residence time are the most important parameters of the later production process.

Критическая температура купратных и органических сверхпроводников

At present, there is no complete theory of superconductivity, which entails the need to solve a number of important research problems. In particular, is no expression capable of describing the critical temperature of all superconducting materials. Superconductors in the transition from their superconducting to normal state are considered. To this end, an analogy between the plasmons in metal and oscillations of superconducting electrons is taken, based of which expressions for the critical temperature and superconducting particle velocity as functions of coherence length and London penetration depth are obtained. The obtained dependences show that the critical temperature increases with increasing the coherence length and decreases with increasing the London penetration depth. The possible coherence length and London penetration depth values for possible room-temperature superconductors are given. The theoretical values of the superconductor critical temperature are in good agreement with the experimentally measured values for organic and cuprate superconductors. Based on the obtained expression for the critical temperature, a generalization of the expression for some alloys, metal compounds, Chevrel phases, and iron pnictides is proposed.

Rheological Characteristics of Reclaimed Asphalt Pavement (RAP) Evaluation using Reclamite Rejuvenating Material

Using reclaimed asphalt pavement (RAP) does not only reduce costs but is also environmentally friendly. In its use, it is very important to know the empirical and rheological properties of the asphalt. The testing in this study used a Dynamic Shear Rheometer (DSR) to test asphalt pen 60/70, RAP and Reclamite rejuvenating material mixed with RAP. The results of the pen asphalt 60/70 empirical test met the Bina Marga 2010 General Specifications of Roads and Bridges, while the RAP showed the characteristics of an aging asphalt. In the rheological test based on SUPERPAVE, from the value of the performance grade (PG), it was found that Reclamite reduced the critical temperature value on RAP, so the PG value was the same as the asphalt pen 60/70. The master curve results also showed that Reclamite can reduce the RAP stiffness modulus near the value of asphalt pen 60/70 stiffness modulus. Meanwhile, as seen from the results of the black diagram, the original condition has a range of phase angle (δ) greater than the RTFOT and PAVT conditions because the asphalt has undergone aging. At the same Sbit, asphalt pen 60/70 has a greater (δ) than RAP, while for RAP added with Reclamite, the value is between the RAP and asphalt pen 60/70 value. This illustrates that the Reclamite rejuvenating material makes RAP more viscous.

Unravelling the interactions between biomedical thermoresponsive polymer and biocompatible ionic liquids

Studies on the phase behavior of thermoresponsive polymers (TRPs) in the presence of ionic liquids (ILs) are an emerging area for the preparation and design of new polymeric materials. The search to understand the influence of ILs on polymers has come into the limelight as a great challenge. Hitherto, limited work on the phase transition behavior of TRPs in the presence of ILs is available. In this work, we studied the phase behavior of poly-N-isopropylacrylamide (PNIPAM) in presence of cholinium chloride ([Ch]Cl), cholinium acetate ([Ch][Ac]), cholinium bitartrate ([Ch][Bit]) and cholinium dihydrogen citrate ([Ch][DHCit]) using various techniques such as UV–Visible absorption spectroscopy, steady-state fluorescence spectroscopy, thermal fluorescence spectroscopy, viscosity (ƞ) and dynamic light scattering (DLS). All cholinium-based ILs studied show qualitatively and quantitatively a similar phase behavior, suggesting it to be quite resilient with respect to changes in the anion of the ILs. However, concentration and orientation of ILs have a varied effect on the phase transition temperature and on the aggregation behavior of PNIPAM. Our temperature dependent experimental results explicitly signifies that lower critical solution temperature (LCST) values decrease with increasing the temperature and concentration of studied ILs, which indicates that hydrophobic interactions are dominating. Anions of IL with their charge densities, hydration capacities and hydration energies leads to the hydrophobicity of PNIPAM + IL aqueous solution. High polarity, owing to the charge of the carboxylate groups in [Ch][DHCit] and [Ch][Bit], and hydrogen bond acceptor capability of the Cl− anion causes their affinity for water inducing ability. This is the first report on the influence of cholinium-based ILs on the phase behavior of the PNIPAM. The current research work provides significant information on the phase transition and aggregation behavior of TRPs in ILs, which paves the way for potential applications in various fields.

Sensitivity of Vegetation on Alpine and Subalpine Timberline in Qinling Mountains to Temperature Change

Alpine timberline is a great place for monitoring climate change. The study of alpine and subalpine timberline in Qinling Mountains has led to early warning that reveals the response and adaptation of terrestrial vegetation ecosystem to climate change. Based on the remote sensing image classification method, the typical timberline area in Qinling Mountains was determined. Temperature and normalized difference vegetation index (NDVI) data were extracted from the typical timberline area based on spatial interpolation and NDVI data. The relationship between NDVI and temperature change and the critical temperature value affecting vegetation response in the timberline area in Qinling Mountains were analyzed. Correlation between NDVI and air temperature in the alpine and subalpine timberline areas of Qinling Mountains exhibited an upward trend, which implied that temperature promotes vegetation activity. A strong correlation between temperature and NDVI in typical timberline areas of Qinling Mountains, and a significant correlation between temperature and NDVI in the early growing season. A phenomenon of NDVI lagging behind air temperature was observed. Temperature response showed synchronization and hysteresis. The correlation between cumulative temperature and vegetation was similar between Taibai Mountain and Niubeiliang timberline, and the correlation between NDVI in April and cumulative temperature in the first 12 months was the strongest. Temperature threshold range of Taibai Mountain timberline played a dominant role in vegetation growth. Our results provide insights and basis for future studies of early warning signs of climate change, specifically between 0.34 and 1.34 °C. The threshold ranges of temperature response of different vegetation types vary. Compared with alpine shrub meadow, the threshold ranges of temperature effect of Coniferous forest and Larix chinensis Beissn. are smaller, implying that these vegetation types are more sensitive to temperature change.