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"Infrared radiation"
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Water Saturation Effects on Thermal Infrared Radiation Features of Rock Materials During Deformation and Fracturing
This paper aims to investigate the water saturation effects on the thermal infrared radiation (IRR) characteristics of rock materials during deformation and fracturing processes. Three kinds of rocks, namely sandstone, granite, and marble, were adopted for tests. Uniaxial compression tests were carried out on oven-dried and water-saturated rock samples. The evolution of IRR temperature on rock surface was monitored and recorded with the aid of an infrared thermographic camera. Test results show that the IRR temperature of saturated samples is apparently higher than that of dry ones subjected to the same axial stress. After water saturation, the heating rate in elastic deformation phase, the IRR temperature increment at peak stress, and the IRR temperature on the new-formed fracture surface have a significant growth compared to dry condition. These indicate that the presence of water facilitates the release of thermal energy. The sensitivities of the heating rates in elastic deformation phase to water saturation are very distinct for the three rocks. This is possibly resulted from the mineral composition of rock types, especially the proportion of calcite and swelling clay minerals. The IRR temperature increment at peak stress for rock not only depends on the moisture condition, but is also relevant to the uniaxial compressive strength.
Journal Article
Characteristics of Infrared Radiation of Coal Specimens Under Uniaxial Loading
An object in its natural state at temperatures greater than -273.15 C generates electromagnetic waves, including infrared radiation (Wu et al. 2000). Coal and rock under loading also produce detectable electromagnetic radiation anomalies including wavelengths in the infrared band (Brady and Rowell 1986; Luong 1987). Through studying the infrared radiation characteristics on the surface of coal and rock specimens under loading conditions, one can derive the relationship between infrared radiation and the mechanical parameters of the specimens under dynamic stress. This information can be used to predict dynamic phenomena including ground pressure, coal bursting, and rock bursting.
Journal Article
Near-Infrared Spectroscopy in Bio-Applications
Near-infrared (NIR) spectroscopy occupies a specific spot across the field of bioscience and related disciplines. Its characteristics and application potential differs from infrared (IR) or Raman spectroscopy. This vibrational spectroscopy technique elucidates molecular information from the examined sample by measuring absorption bands resulting from overtones and combination excitations. Recent decades brought significant progress in the instrumentation (e.g., miniaturized spectrometers) and spectral analysis methods (e.g., spectral image processing and analysis, quantum chemical calculation of NIR spectra), which made notable impact on its applicability. This review aims to present NIR spectroscopy as a matured technique, yet with great potential for further advances in several directions throughout broadly understood bio-applications. Its practical value is critically assessed and compared with competing techniques. Attention is given to link the bio-application potential of NIR spectroscopy with its fundamental characteristics and principal features of NIR spectra.
Journal Article
Gender-Related Effect in Oxygenation Dynamics by Using Far-Infrared Intervention with Near-Infrared Spectroscopy Measurement: A Gender Differences Controlled Trial
Many studies have indicated the microcirculation can directly respond to disease-related symptoms. However, the capacity of microcirculation would vary due to the gender differences. Near-infrared spectroscopy (NIRS) is a noninvasive technique to monitor tissue oxygenation dynamics. In this study, the far-infrared (FIR) source was used for physiological intervention of microcirculation. The experimental results show that the nature difference of oxygenation status exists between male and female during FIR irradiation. Therefore, we suggest the NIRS-based assessment should be calibrated with the gender-related effect for clinical diagnosis of peripheral arterial disease.
Journal Article
Interfacial engineering of Bi2S3/Ti3C2Tx MXene based on work function for rapid photo-excited bacteria-killing
Abstract
In view of increasing drug resistance, ecofriendly photoelectrical materials are promising alternatives to antibiotics. Here we design an interfacial Schottky junction of Bi
2
S
3
/Ti
3
C
2
T
x
resulting from the contact potential difference between Ti
3
C
2
T
x
and Bi
2
S
3
. The different work functions induce the formation of a local electrophilic/nucleophilic region. The self-driven charge transfer across the interface increases the local electron density on Ti
3
C
2
T
x
. The formed Schottky barrier inhibits the backflow of electrons and boosts the charge transfer and separation. The photocatalytic activity of Bi
2
S
3
/Ti
3
C
2
T
x
intensively improved the amount of reactive oxygen species under 808 nm near-infrared radiation. They kill 99.86% of
Staphylococcus aureus
and 99.92% of
Escherichia coli
with the assistance of hyperthermia within 10 min. We propose the theory of interfacial engineering based on work function and accordingly design the ecofriendly photoresponsive Schottky junction using two kinds of components with different work functions to effectively eradicate bacterial infection.
Journal Article
Effects of far-infrared radiation temperature on drying characteristics, water status, microstructure and quality of kiwifruit slices
Far-infrared radiation (FIR) drying is an advanced technique that has recently been applied in food processing. In order to reveal the effects of FIR temperature on dehydration process and quality characteristics of kiwifruit slices, FIR drying experiments on kiwifruit slices were conducted. Low-field nuclear magnetic resonance, scanning electron microscopy, colorimeter and chemical analysis were applied to explore the dynamic water states, microstructure, color changes and nutritional components of kiwifruit slices at different FIR temperatures. The results showed that drying time reduced by 57.9% and average drying rate increased by 137.5% as FIR temperature increased from 120 to 280 °C. The water mobility and distribution in kiwifruits changed with the extension of drying time, and increasing FIR temperature could accelerate the migration and removal of moisture. Higher FIR temperature could produce more cavities and larger channels in dried samples. An increase in FIR temperature decreased
L
*
but increased
a
*
values of dried kiwifruits and affected total phenolic content, total flavonoids content and Vitamin C content. Therefore, FIR drying is a promising method to improve drying rate as well as protect product quality of kiwifruit slices.
Journal Article
An ultrahot gas-giant exoplanet with a stratosphere
Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere. If upper layers are cooler than lower layers, molecular gases will produce absorption features in the planetary thermal spectrum. Conversely, if there is a stratosphere-where temperature increases with altitude-these molecular features will be observed in emission. It has been suggested that stratospheres could form in highly irradiated exoplanets, but the extent to which this occurs is unresolved both theoretically and observationally. A previous claim for the presence of a stratosphere remains open to question, owing to the challenges posed by the highly variable host star and the low spectral resolution of the measurements. Here we report a near-infrared thermal spectrum for the ultrahot gas giant WASP-121b, which has an equilibrium temperature of approximately 2,500 kelvin. Water is resolved in emission, providing a detection of an exoplanet stratosphere at 5σ confidence. These observations imply that a substantial fraction of incident stellar radiation is retained at high altitudes in the atmosphere, possibly by absorbing chemical species such as gaseous vanadium oxide and titanium oxide.
Journal Article
Iron Oxide Nanoparticles in Photothermal Therapy
Photothermal therapy is a kind of therapy based on increasing the temperature of tumoral cells above 42 °C. To this aim, cells must be illuminated with a laser, and the energy of the radiation is transformed in heat. Usually, the employed radiation belongs to the near-infrared radiation range. At this range, the absorption and scattering of the radiation by the body is minimal. Thus, tissues are almost transparent. To improve the efficacy and selectivity of the energy-to-heat transduction, a light-absorbing material, the photothermal agent, must be introduced into the tumor. At present, a vast array of compounds are available as photothermal agents. Among the substances used as photothermal agents, gold-based compounds are one of the most employed. However, the undefined toxicity of this metal hinders their clinical investigations in the long run. Magnetic nanoparticles are a good alternative for use as a photothermal agent in the treatment of tumors. Such nanoparticles, especially those formed by iron oxides, can be used in combination with other substances or used themselves as photothermal agents. The combination of magnetic nanoparticles with other photothermal agents adds more capabilities to the therapeutic system: the nanoparticles can be directed magnetically to the site of interest (the tumor) and their distribution in tumors and other organs can be imaged. When used alone, magnetic nanoparticles present, in theory, an important limitation: their molar absorption coefficient in the near infrared region is low. The controlled clustering of the nanoparticles can solve this drawback. In such conditions, the absorption of the indicated radiation is higher and the conversion of energy in heat is more efficient than in individual nanoparticles. On the other hand, it can be designed as a therapeutic system, in which the heat generated by magnetic nanoparticles after irradiation with infrared light can release a drug attached to the nanoparticles in a controlled manner. This form of targeted drug delivery seems to be a promising tool of chemo-phototherapy. Finally, the heating efficiency of iron oxide nanoparticles can be increased if the infrared radiation is combined with an alternating magnetic field.
Journal Article
Photoinduced semiconductor-metal transition in ultrathin troilite FeS nanosheets to trigger efficient hydrogen evolution
The exploitation of the stable and earth-abundant electrocatalyst with high catalytic activity remains a significant challenge for hydrogen evolution reaction. Being different from complex nanostructuring, this work focuses on a simple and feasible way to improve hydrogen evolution reaction performance via manipulation of intrinsic physical properties of the material. Herein, we present an interesting semiconductor-metal transition in ultrathin troilite FeS nanosheets triggered by near infrared radiation at near room temperature for the first time. The photogenerated metal-phase FeS nanosheets demonstrate intrinsically high catalytic activity and fast carrier transfer for hydrogen evolution reaction, leading to an overpotential of 142 mV at 10 mA cm
and a lower Tafel slope of 36.9 mV per decade. Our findings provide new inspirations for the steering of electron transfer and designing new-type catalysts.
Journal Article