Mid Temperature Research Articles

Temperature Sensitive Conductivity Studies of NBT-Based Lead-Free Ternary System

The frequency and temperature dependence electrical conduction characteristics of a lead-free 0.78NBT-0.2ST-0.02BT ternary system were investigated by impedance spectroscopy. Variation of real part of conductivity with frequency reveals a frequency independent and a dispersive region obeying Jonscher power law. The relatively higher values of S-parameter in the mid temperature range envisage the presence of localized relaxation or hopping of the charge carriers. The activation energies calculated from the temperature dependent hopping frequency and dc conductivity, portray the increase of unsuccessful hops of the charge carriers with increase in temperature according to the Jump relaxation model. Interestingly the conductivity values could be curbed by introduction of BT in to NBT-ST. The collapsing of the scaled conductivity spectrum in to a single master curve depicts the temperature independent conduction relaxation mechanism.

Intermolecular Potential-Based Equations of State from Molecular Simulation and Second Virial Coefficient Properties.

The importance of both the Boyle temperature ( TB) and temperature maximum ( Tmax) for the ability of intermolecular potential-based equations of state to accurately predict second virial coefficient ( B) behavior was examined. The TB, Tmax, and B vs T behavior of several Lennard-Jones equations of state, developed from molecular simulation data, were compared with exact theoretical values. The analysis spanned low ( T ≤ TB), mid ( TB < T ≤ Tmax), and high ( T ≫ Tmax) temperatures. The value of TB was accurately predicted by most equations of state studied, whereas most failed to adequately predict Tmax. The ability to accurately predict both TB and Tmax appears to be correlated with the accurate prediction of B values for the entire range of temperatures. This provides a useful criterion to improve future potential-based equations of state. The Mecke et al. and Thol et al. Lennard-Jones equations of state yielded the most accurate results. In some cases, a many-fold improvement in accuracy was observed compared with alternative equations of state. The exact B data were also used to obtain accurate polynomial relationships covering different ranges of temperatures.

Natural deep eutectic solvents as a storage medium for human interferon-α2: a green and improved strategy for room-temperature biologics

The inherent vulnerability of protein biologics to high temperature is the origin of their limited use in clinical settings where proper storage and handling systems are not available. Herein, we demonstrate the first application of natural deep eutectic solvents (NADES) as a temperature-stable storage medium for a real therapeutic protein, human interferon-alpha 2 (IFN-α2). A formulation of IFN-α2 based on a NADES composed of choline chloride and fructose at a 1:1 molar ratio (CCl:Fru) had no influence on the activity of IFN-α2. The NADES provided an appropriate environment for effective protection of IFN-α2 from thermal denaturation at mid (37°C) and high (70°C) temperatures during long-term (90 days) and short-term (2h) storage. Protein stability in the presence of CCl:Fru was demonstrated by orthogonal or complementary methods, including in vitro activity assay, circular dichroism spectroscopy and extrinsic fluorescence spectroscopy. In view of their biocompatibility, customizable properties, and the simplicity of synthesis and use, NADESs are suggested as a green and improved short-term and long-term storage medium that could facilitate the development of room-temperature biologics.

Effect of Processing Variables on Tensile Modulus and Morphology of Polyethylene/Clay Nanocomposites Prepared in an Internal Mixer

A comparative study on effect of internal mixer on high density Polyethylene (HDPE)/clay nanocomposites preparation was done. Effect of temperature, rotor rotation (rpm), and mixing time, as well as rotor type (Roller and Banbury) on mechanical properties and morphology of HDPE/clay nanocomposites were studied using Box-Behnken experimental design. The model was developed according to secant modulus and confirmed to morphology analysis using Transmission Electron Microscopy (TEM). The finding suggests that there is different mechanisms occurred in each rotor to improve the mechanical properties. The mechanism in Roller is medium shear and medium diffusion, while Banbury is high shear and low diffusion. The difference in mechanism to disperse the clay particles attribute to the different optimum processing conditions in each rotor. The settings for roller samples are predicted around mid temperature, mid speed, and mid mixing time. There is no optimum setting for Banbury within the processing boundaries. The best settings for Banbury are at low, high, low settings. The morphology results showed a hybrid composite structure, with some exfoliations and some intercalations. There was a correlation between better mechanical properties and morphology with more exfoliation and thinner intercalated particles.

Thermoelectric properties of p-type sb-doped Cu2SnSe3 near room and mid temperature applications

In this study, we report low and mid temperature range thermoelectric properties of Sb-substituted Cu2SnSe3 compounds. The Cu2Sn1−xSbxSe3 (0 ≤ x ≤ 0.04) alloys were prepared using conventional solid-state reaction followed by spark plasma sintering. The crystal structure was characterized using XRD and it reveals that all the samples exhibit cubic structure with space group $$\stackrel{-}{4}3m$$. The electrical transport characteristics indicate degenerate semiconducting behavior. Electrical resistivity was found to follow small polaron hopping (SPH) model in the entire temperature range of investigation. The Seebeck coefficient data reveals that the majority of charge carriers are holes and the analysis of Seebeck coefficient data gives negative values of Fermi energy indicating that the Fermi energy is below the edge of valence band. The electronic contribution (κe) for total thermal conductivity is found to be less than 1%. The maximum ZT value of 0.64 is observed for the sample with x = 0.03 (at 700 K) which is approximately 2.3 times that of the pristine sample.

An Sn-induced resonant level in β-As2Te3.

Distortion of the density of states by an impurity-induced resonant level has been shown to provide an effective strategy to improve the thermoelectric performance of semiconductors such as Bi2Te3, PbTe or SnTe. Here, combining first-principles calculations and transport property measurements, we demonstrate that Sn is a resonant impurity that distorts the valence band edge in p-type β-As2Te3. This remarkable effect is characterized as a prominent, sharp peak in the electronic density of states near the Fermi level. To illustrate the particular influence of Sn on the thermopower of β-As2Te3, the theoretical Ioffe-Pisarenko curve, computed within the Boltzmann transport theory, is compared with the experimental results obtained on three series of polycrystalline samples with substitution of Ga and Bi for As and I for Te. While Ga and I behave as conventional, rigid-band-like dopants and follow theoretical predictions, Sn results in significant deviations from the theoretical curve with a clear enhancement of the thermopower. Both electronic band structure calculations and transport property measurements provide conclusive evidence that this enhancement and hence, the good thermoelectric performances achieved at mid temperatures in β-As2-xSnxTe3 can be attributed to a resonant level induced by Sn atoms. The possibility to induce resonant states in the electronic band structure of β-As2Te3 opens new avenues to further optimize its thermoelectric performance.

Randomized response surface pathway design with odd response outcomes in a Latin Square designed study

Randomized response surface pathway design with odd response outcomes in a Latin Square designed study Trond Holand,1 Kristian Ellingsen,2 Sagita Dewi,1,3 Stig Larsen1 1Centre for Epidemiology and Biostatistics, Department of Production Animal Clinical Sciences, Faculty of Veterinary Science, Norwegian University of Life Science, 2Norwegian Veterinary Institute, Oslo, Norway; 3Bali Indera Hospital, Government of Bali Province, Denpasar, Bali, Indonesia Background: Response surface pathway (RSP) design has been recently developed and described for dose-finding studies. The aim of this paper was to introduce and demonstrate additional procedures to strengthen and generalize the design and combine RSP with classical study design.Materials and methods: Nine bull calves and six heifer calves were included in an unbalanced 2&nbsp;&times;&nbsp;2 Latin Square (LSQ) designed study with large and small aperture bottle teats. The two LSQ sequences were performed with independent randomized three-level between-patient RSP design with an odd number of response classifications. The milk temperature window was 8&deg;C&ndash;38&deg;C with a mid temperature of 23&deg;C. X-rays of the abdominal cavity were taken before, during, and immediately after intake of milk and recorded as &ldquo;milk&rdquo;, &ldquo;trace&rdquo;, or &ldquo;no milk&rdquo;. Based on the results of the first design level, the milk temperatures for five calves in the second design level were obtained by a randomization procedure. A similar procedure was performed for seven calves in the third design level. Adjustment of the dose from one design level to the next was based on a k-adjustment factor estimated to ensure coverage of the entire predefined dose window.Results: Starting with a low number of subjects and increasing this number with increasing design levels reduces the sample size without reducing the power. The suggested randomization procedure worked as expected. No milk in Rumen was recorded and minimum milk temperature (MMT) was estimated to be &le;8&deg;C for both teats. The odd number of response categories increases the flexibility of RSP, enabling category redefinition in hindsight from &ldquo;trace&rdquo; to &ldquo;uncertain&rdquo;. After category redefinition, MMT for large bottle teat was estimated to be 14.3&deg;C (95% confidence interval: 8.3&ndash;20.3&deg;C), but 8&deg;C for small.Conclusion: The suggested changes and additional procedures increase the strength and flexibility of the RSP design. Keywords: k-adjustment factor, Latin Square design, patient reduction in clinical trials, randomized response surface pathway design

Influence of season, age and management on scrotal thermal profile in Murrah bulls using scrotal infrared digital thermography.

The aim of the present study was to examine the effects of non-genetic factors on scrotal thermographic profile viz., proximal pole temperature (PPT °C), mid pole temperature (MPT °C), distal pole temperature (DPT °C) and ocular temperature (OcT) of Murrah (Bubalus bubalis) breeding bulls. A total of 109 buffalo bulls, maintained at three semen stations (SS), were monitored for scrotal surface and ocular temperatures using infrared thermography twice daily during rainy, winter and summer seasons using an FLIR i5 infrared camera and temperatures were measured. Thermograms were analysed by FLIR QuickReport v.1.2 SP2 software. Statistical analysis revealed that semen station, season, temperature humidity index (THI), housing system and timing of observations had significant (P<0.05) effect on scrotal surface temperature (SST) and OcT. In SS-I, the PPT and MPT were significantly (P<0.05) higher as compared to SS-II and SS-III. THI had significant (P<0.05) effect on SST and OcT, whereas PPT (°C), MPT (°C), DPT (°C) and OcT (°C) values during high THI (>80.88; <0.05) period were higher as compared to medium THI period (70.06-80.88) and during low THI period (<70.06). Temperature gradient (TG) of the testes was significantly (P<0.05) higher during low THI period (4.50±0.06°C) as compared to medium THI (2.38±0.03°C) and high THI (1.61±0.05°C). Season of the year had a significant effect (P<0.05) on the SST and OcT. During the rainy season, PPT (34.50±0.09°C), MPT (33.44±0.12°C) and DPT (32.11±0.15°C) were significantly (P<0.05) higher as compared to winter and summer seasons. Age of the bulls had non-significant effect on SST and OcT but had a marked influence on thermal profile of scrotum. It could be concluded semen station, season, temperature humidity index, housing system and timing of observations had a significant influence on scrotal surface temperature. The monitoring of scrotal surface temperature by infrared thermography was found to be useful in evaluating the effects of thermal stress on physiology and health of buffalo bulls.

Numerical study of the accuracy of temperature measurement by thermocouples in small-scale reactors

Proper temperature measurement is imperative in any laboratory study if reliable data are to be obtained, particularly in the field of chemical kinetics. In this paper we analyze in silico some typical thermowell configurations used in small-scale reactors by coupling computational fluid dynamics (CFD) with conjugated heat transfer phenomena. This allows us to identify deviations in measurements arising from thermal radiation and self-conductivity in mid and high temperature ranges, in addition to radial temperature gradients. A novel design is proposed and optimized by additional simulation, showing potential for faster and more accurate temperature measurements.

Rapid in-situ synthesis of nanocrystalline magnesium silicide thermo-electric compound by spark plasma sintering

Magnesium silicide (Mg2Si) is the one of the most attractive and promising green thermo-electric material to convert the heat into electricity in the mid temperature range (RT to 600°C). However, synthesizing of Mg2Si compound through liquid and solid state processing carries several challenges such as processing time, inhomogenous stoichiometry and phase purity. The alternative method is demonstrated by rapid in-situ synthesis of pure nano-crystalline Mg2Si doped with Bi (0–0.025at.%) by spark plasma sintering (SPS). XRD and electron microscopy studies confirm the formation of Mg2Si compound and EDS confirm chemical and doping homogeneity. The superior power factor of 11µW/cm-k2 is achieved at 550°C.

Dynamics of surface urban biophysical compositions and its impact on land surface thermal field

Urban heat effects over Abeokuta city, Nigeria have raised interests by relevant scientific communities owing to the recent infrastructural and economic growth of the area. In this paper, the surface temperatures and land surface biophysical types retrieved from Landsat TM, and ETM+images of Abeokuta city for 1984, 2003 and 2014 were analyzed. The images acquired were classified into appropriate land cover types using supervised classification schemes and a change detection analysis was carried out on the classified imageries using land change modeller (LCM) to evaluate the extent of modification of surface features. A quantitative approach was used to explore the relationships among temperature, surface biophysical components and spectral indices. Results showed that impervious surface and water areas were found to be correlated positively with high temperatures. Conversely, vegetated areas and bare surfaces correlated positively with mid temperature zones. The overall metrics error between the regression-modeled LST and the retrieved LST for the study area is quite low, between 2.63 °C for root mean square error (RMSE) and 2.17 °C for mean absolute error (MAE). This study concluded that, areas with increasing built-up surfaces and surface reflectivity will bring about LST rise, and consequently leads to urban heat island development.

Isolation of cyanophage CrV infecting Cylindrospermopsis raciborskii and the influence of temperature and irradiance on CrV proliferation

A lytic virus that infects a European strain of the freshwater filamentous cyano-bacterium Cylindrospermopsis raciborskii was isolated from a lake in the Netherlands and partially characterised. With a genome size of 110 +/- 15 kb, an icosahedral capsid of 65 +/- 1 nm (n = 22) and a long non-contractile tail of 612 +/- 31 nm (n = 15), this dsDNA cyanophage CrV appears to belong to the Siphoviridae family. CrV was highly host specific, not infecting other filamentous cyano bacteria species isolated from the same lake, nor 4 Australian strains of C. raciborskii. The latent period of this cyanophage was 20-24 h. Varying the irradiance affected cyanophage-host inter actions: at low light (20 mu mol quanta m(-2) s(-1)) the latent period was 1.3 times longer compared with at mid light (90 mu mol quanta m-2 s(-1)); burst size at mid light was 332 CrV per lysed host cell, at low light it was halved (48%) and at high light (250 mu mol quanta m(-2) s(-1)) the burst size was further reduced to only 14% of that of mid light. Temperature also affected the virus growth characteristics: the CrV latent period at high temperature (30 degrees C) was reduced to just 11% (compared with a mid temperature of 22 degrees C), but still the burst size increased to 541 CrV per lysed host cell; at low temperature (15 degrees C) the latent period was prolonged 1.3-fold and the burst size was reduced to 43%. Our findings indicate that ecologically relevant environmental factors can affect the extent of viral lysis of C. raciborskii, advancing our understanding of the spread of this invasive cyanobacterium across Europe.

ChemInform Abstract: Mg9Si5: A Potential Non‐toxic Thermoelectric Material for Mid‐Temperature Applications.

AbstractFirst principles density functional theory based calculations indicate Mg9Si5 to be a potential non‐toxic mid temperature thermoelectric material, operable in the 400—600 K range.

A Quantitative Assessment of Surface Urban Heat Islands Using Satellite Multitemporal Data over Abeokuta, Nigeria

The fast urban expansion has led to the transformation of the natural landscape into anthropogenic surfaces. The city of Abeokuta, for instance, is located in a region experiencing rapid urbanization, which has produced a remarkable effect on the surface thermal response. This effect significantly influences urban internal microclimatology on a regional scale. In this study, the surface temperatures and land cover types retrieved from Landsat TM and ETM+ images of Abeokuta city for 1984, 2003, and 2014 were analyzed. A quantitative approach was used to assess surface urban heat islands through the relationships among surface temperature and land cover types. Results showed that impervious surface areas were found to be correlated positively with high temperatures. Conversely, vegetated areas and bare surfaces correlated positively with mid temperature zones. This study found that areas with increasing impervious surfaces will accelerate LST rise and consequently lead to increasing effect of surface urban heat islands. These findings pose a major challenge to urban planners. However, the study would help to quantify the impacts of different scenarios (e.g., vegetation loss to accommodate urban growth) on LST and consequently to devise appropriate policy measures.

Performance analysis of a refrigerant extracting twin screw compressor employed in multi-temperature heat pump systems

Heat pump systems are widely used in heat recovery applications where high temperature waste heat is abundantly available. High temperature heat pumps are capable of recovering heat from the condenser of a refrigeration system to supply heat for processing or heating. However, conventional systems are unable to supply heat at more than one temperature level, while significant efficiency loss is caused by the large condensing temperature difference between high and mid temperature condensers. In this paper, a novel type of refrigerant extracting screw compressor and a modified system is designed. Mathematical models are formulated for the working process and performance prediction. Therefore, the pressure of refrigerant within the compressing chamber and the COP of the heat recovery multi-temperature heat pump system are calculated. Furthermore, the influence of the internal volumetric ratio, operating condition, properties of refrigerant extraction and mid-stage condensing temperature on the performance are discussed.

Angular solar absorptance and thermal stability of W/WAlN/WAlON/Al2O3-based solar selective absorber coating

In this paper, we report the solar absorptance property of a new tandem absorber consisting of layers W/WAlN/WAlON/Al2O3 that holds promise for solar thermal energy harvesting. The coating was prepared by DC/RF magnetron sputtering on stainless steel substrate. The performance of the film was investigated by measuring the reflectance spectra in the wavelength range of 250–2500nm and most importantly by varying the incident angle from 18° to 68°. The effect of thermal annealing on the optical properties, microstructure and morphology of the solar selective absorber coating was also explored. The thermal annealing of the coating at 350°C till 550h in air did not result in any significant change in the spectral properties of the absorber coating. The excellent thermal stability and wide range of angular absorptance of this multilayer coating indicate the potential for application as selective coating in mid temperature photothermal conversion systems.

Long-term consequences of high incubation temperature in a wild bird population.

Because incubation by birds is energetically costly, parents frequently trade off investment in incubation against self-maintenance. This can be manifested by a reduction in incubation temperature, which comes at high somatic costs for nestlings. The extent to which these costs constrain fitness is poorly understood. We incubated wild blue tit clutches at three biologically relevant temperatures and subsequently recorded winter survival and survival to the breeding season. Fledglings from the coldest treatment (35.0°C) survived less well than other fledglings, but the proportion of winter and breeding survivors did not differ significantly between treatments. However, survival probability in both seasons increased with body mass at fledging in birds from low and mid incubation temperatures, but decreased with fledging body mass in the high-temperature treatment. Mid-temperature nestlings were heavier as adults, weighing 7% more than low- and high-temperature survivors. Thus, high incubation temperature can be beneficial in the short term, but costs of accelerated embryonic development may equal those of protracted development in the long term. Such hidden consequences of faster development could maintain natural selection for average incubation temperature.

표고 톱밥재배용 교배균주의 자실체 온도형 및 생산성 비교

실내에서 육성된 117개 교배균주를 시험 재배하여 자실체의 특성 및 생산성을 검정하고 결과가 우수한 07-55, 07-66, 07-84, 07-93, 07-117균주를 선발하고 이들의 모균주들과 확대 재배하여 모균주와의 생산성을 비교한 결과 각 균주의 생산성은 07-66균주가 36.1%의 회수율을 보여 가장 높게 나타났으며 07-117균주는 35.6%, 07-93균주는 27.1%, 08-84균주는 25.7%로 조사되었고 07-55균주는 가장 생산성이 낮은 6.5%로 조사되었다. 07-93 균주와 07-66균주는 생산성이 높으나 대가 긴 특성을 보였고 07-117균주는 전체적인 자실체 품질이 다른 균주들보다 낮았다. 또한 모균주와 교배균주간에 재배를 통한 온도형 분석 결과 07-117균주는 고온형, 07-66 및 07-84균주는 중온형, 07-55 및 07-93균주는 저온형으로 구분되었으며 07-93균주는 비교적 버섯발생온도범위가 넓은 가능한 균주이나 품질이 저조하였다. We cultivated 117 hybrid strains of Lentinula edodes in greenhouse. 5 hybrid strains(07-55, 07-66, 07-84, 07-93 and 07-117) were selected from comparison of their characteristics of fruiting body and productivity. Biological efficiency of 5 hybrid strains was investigated 36.1(07-66), 35.6(07-117), 27.1(07-93), 25.7(07-84) and 6.5%(07-55), respectively. Selected strains 07-66, 07-117 and 07-93 showed high biological efficiency but observed commercially low quality fruiting body. Temperature type of fruiting body of 5 hybrid strains observed as follows high temperature type(07-117), mid temperature type(07-66 and 07-84) and low temperature type(07-55 and 07-93). Temperature type of fruiting body of 07-93 strain has wide range relatively. In the results, 07-84 strain was selected finally with consideration for quality of fruiting body, productivity and temperature type(<TEX>$8-21^{\circ}C$</TEX>) in farm test.

Heat capacity and thermodynamic functions of brookite TiO2

This work represents the first report on the heat capacity of brookite TiO2, which was measured using a Quantum Design physical property measurement system (PPMS) in the temperature range of 2K to 300K. The experimental data were fitted using a series of theoretical functions for low temperatures (T<15K), orthogonal polynomials for mid temperatures (15<T<75K), and a combination of Debye and Einstein functions for high temperatures (T>75K), from which the thermodynamic functions of brookite TiO2 were calculated. The standard molar entropy and molar enthalpy for brookite TiO2 at T=298.15K were determined to be 52.61±0.53J·K−1·mol−1 and 9.03±0.09kJ·mol−1, respectively, leading to a Gibbs free energy of −6.65±0.18kJ·mol−1. Strikingly, this Gibbs free energy was found to be slightly less than those reported for rutile TiO2 (−6.377kJ·mol−1) and anatase TiO2 (−6.198kJ·mol−1) (Smith et al., 2009). Further data analyses demonstrated that the thermal stability of TiO2 polymorphs follows a sequence of anatase<rutile<brookite at T=298.15K.

Rheological evaluation of polymer modified asphalt binders

The microstructure and dynamic rheological characteristics of asphalt containing different polymer modifiers (crumb rubber, styrene-butadiene-styrene and crumb rubber mix with styrenebutadiene-styrene) at mid and high service temperature levels were investigated by using scanning electron microscopy(SEM), dynamic shear rheometer(DSR) and repeat creep test. The main objective of the investigation was to rank the modifiers based on their effect on performance characteristics of asphalt under service conditions. To evaluate the effect of different modifiers on the viscoelastic response of asphalt, the temperature and frequency dependences of the dynamic viscoelastic properties were compared. The mid-temperature fatigue resistance and high-temperature rutting resistance of three polymer modified asphalts were evaluated to predict their field performance in roads. Based on the current results, an improved rutting factor was proposed to determine the rutting resistance of asphalt pavements. In addition, the viscous stiffness (Gv), defined as the reciprocal of viscous compliance, was used to evaluate the high-temperature deformation resistance of asphalt mixtures. The experimental results indicate that the asphalt containing crumb rubber only shows superior performance at mid and high service temperatures in all three modified asphalt binders due to the action of the crumb rubber.