Study of the mutual coupling characteristics of the oxidation thermal effect and microstructural evolution of gas-containing coal

Besides be affected by coal confining pressure, coal seams are also be affected by the surrounding pressure during mining. To understand the heat release characteristics and microstructural evolution of oxidization within coal under different gas pressures is of great significance. For this reason, a combination of theoretical research and test analysis was adopted, which includes differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and mercury intrusion method (MIP). The influences of gas phase transformation and migration on the oxidation and spontaneous combustion processes of gas-containing coal under different gas pressures were explored. The distributions and variations in heat release, gas derivation, pore structure and functional group characteristics during the oxidation of gas-containing coal were analysed. We clarified the cross-coupling attributes of heat, seepage and chemical properties in the oxidation of gas-containing coal. The experimental results show that the methane within coal migrates outward in pores with the increase of temperature, which inhibits the penetration and adsorption of oxygen, thereby inhibiting the coal‑oxygen composite reaction and delaying the heat accumulation within coal. There is a positive correlation between loose and porous characteristics of coal and gas pressure. With the continuous increase of coal temperature, the pore connectivity of high-pressure gas-containing coal is enhanced, which increases the risk of coal spontaneous combustion. The research results are of great significance to the theoretical research on the prevention and prediction of spontaneous combustion of gas-containing coal.

A Comparative Histological Study of Gingival Depigmentation by 808 and 445 nm Diode Lasers

Introduction: Using lasers in melanin depigmentation is one of the main fields of interest for dental practitioners and patients. However, it is important to know what would happen inside the tissue and how the cells would interact inside the tissue with a laser. Methods: In this study, we used both wavelengths of 445 nm and 808 nm on sheep gingiva to find out the effects and side effects of these diode lasers while using them for gingival depigmentation. Results: After microscopic evaluation, we concluded that 808 nm and 445 nm lasers with a power of 1 W are safe enough to use in the depigmentation of gingiva, and both lasers are highly effective in melanin pigments which are located in basal membrane. Conclusion: The 445 nm blue laser produced a less thermal effect, which means it is safer to be used in gingival hyperpigmentation than a diode laser.

A modeling study of the effect of an alternating magnetic field on magnetite nanoparticles in proximity of the neuronal microtubules: A proposed mechanism for detachment of tau proteins

BACKGROUND AND OBJECTIVE

It is known that the disintegration of microtubules in neurons occurs in response to the phosphorylation of the tau proteins that promotes the structural instability of the microtubules, as one of the factors underlying the onset of Alzheimer's disease (AD).

METHODS

In this study, the mechanical variations undergone by the tau protein's and microtubule's structures due to the action of intrinsic magnetite nanoparticles inside the brain tissue have been computationally modeled using the finite element (FEM) method.

RESULTS

The von Mises stress induced by magnetite nanoparticles, subject to an applied alternating magnetic field, leads to local heating and mechanical forces, prompting a corresponding deformation in, and displacement of, the microtubule and the tau protein.

CONCLUSIONS

The induction of these deformations would increase the probability of the microtubules' depolymerization, and hence their eventual structural disintegration.

Temperature Quantification and Temperature Control in Optical Tweezers

Optical tweezers are widely used to investigate biomolecules and biomolecular interactions. In these investigations, the biomolecules of interest are typically coupled to microscopic beads that can be optically trapped. Since high-intensity laser beams are required to trap such microscopic beads, laser-induced heating due to optical absorption is typically unavoidable. This chapter discusses how to identify, quantify, and control thermal effects in optical tweezers. We provide a brief overview of the reported causes and effects of unwanted heating in optical tweezers systems. Specific details are provided on methods to perform a temperature-independent trap calibration procedure. Finally, an effective temperature-control system is presented, and we discuss the operation of this system as well as the methods to measure the temperature at the optically trapped particle.

Superpulse thulium fiber laser lithotripsy: an in vitro comparison of 200 μm and 150 μm laser fibers

PURPOSE

To investigate the thermal effects, stone retropulsion and ablation rate of SuperPulse Thulium-fiber laser (SP TFL) with two different surgical fibers of 200 and 150 μm in diameter.

METHODS

SP TFL (NTO IRE-Polus, Fryazino, Russia) performance with 200 and 150 μm fibers (NTO IRE-Polus, Fryazino, Russia) was evaluated. Before each test, the laser fiber was cleaved, and the power measurement was taken to verify the actual laser output power. To compare the laser fibers in well-controlled environments, a number of setups were used to assess retropulsion, ablation efficacy, fiber burnback, energy transmission, and safety.

RESULTS

Power measurements performed before each test revealed a 4.7% power drop for a 200 μm fiber SP TFL (14.3 ± 0.5 W) and 7.3% power drop for a 150 μm fiber SP TFL (13.9 ± 0.5 W) versus the nominally indicated power (15.0 W). Retropulsion with the TFL was minimal and comparable between fibers. We found no clinically relevant temperature differences between SP TFL with either 200 or 150 μm fibers. The ablation efficacy tended to be comparable under most parameters. Yet, we did observe a decreased diameter of residual fragments after the ablation with a 150 μm fiber.

CONCLUSION

The smaller fiber (150 μm) is not inferior to 200 μm fiber in terms of fiber burnback, retropulsion, safety, and ablation rate. Moreover, it has the potential to decrease the diameter of fragments during lithotripsy, which may facilitate dusting during RIRS.

Temperature dynamics in different body regions of decomposing vertebrate remains

The decomposition of vertebrates is controlled largely by external temperature, yet internal temperatures can also play an important role but are generally poorly documented. In this study, we compared continuous hourly temperature recordings from the mouth, under the head, right chest and right abdomen, and in the rectum of one refrigerated human and one fresh pig cadaver during 29 days of decomposition. Each cadaver differed in its internal starting temperature, thus providing two contrasting case studies for examining temperature dynamics among body regions. We used time-series analysis methods common to hydrology to reveal key differences in internal temperature dynamics. Within both cadavers, the chest region experienced the highest average temperatures, and the mouth experienced the highest maximum hourly temperature. Temperatures exceeded 30 °C inside the pig for between 40% (rectum) and 75% (chest) of the duration of the study, but for only 20% (rectum) and 35% (chest) of the time in the human. Our study provides evidence of the different thermal trajectories occurring in different body regions, and some similarities between two cadavers despite their different starting thermal conditions. These results improve our understanding of why decomposition occurs at different rates within the same cadaver, and that the location of blowfly larvae collections should be noted to improve estimates of the post-mortem interval.

A Systematic Thermal Analysis for Accurately Predicting the Extrusion Printability of Alginate-Gelatin-Based Hydrogel Bioinks

Three-dimensional (3D) bioprinting has significant potential for addressing the global problem of organ shortages. Extrusion printing is a versatile 3D bioprinting technique, but its low accuracy currently limits the solution. This lack of precision is attributed largely to the complex thermal and dynamic properties of bioinks and makes it difficult to provide accurate estimations of the printed results. It is necessary to understand the relationship between printing temperature and materials’ printability to address this issue. This paper proposes a quantitative thermal model incorporating a system’s printing temperatures (syringe, ambient, and bioink) to facilitate accurate estimations of the printing outcomes. A physical model was established to reveal the relationship between temperature, pressure, and velocity in guiding the printing of sodium alginate–gelatin composite hydrogel (a popular bioink) to optimize its extrusion-based printability. The model considered the phenomenon of bioink die swells after extrusion. A series of extrusion experiments confirmed that the proposed model offers enhanced printing outcome estimations compared with conventional models. Two types of nozzles (32- and 23-gauge) were used to print several sets of lines with a linewidth step of 50 mm by regulating the extrudate’s temperature, pressure, and velocity separately. The study confirmed the potential for establishing a reasonable, accurate open-loop linewidth control based on the proposed optimization method to expand the application of extrusion-based bioprinting further.

Thermal effects on the electrical characteristics of Malan loess

Malan loess is a common engineering geological material in Northwest China, which is often used in many engineering constructions. In this paper, the electrical properties of loess under high temperature environment are studied, which provides theoretical basis for engineering construction. The remolded loess samples are heated by different temperatures between 25 and 900 °C under laboratory conditions. Then, the surface features and electrical properties are measured and analyzed. The major findings are as follows: (1) The effect of high temperature on different electrical parameters of loess is different. As temperature increases, a series of physicochemical reactions occur in the loess; as a result, the resistance and impedance of loess samples initially increase and then decrease. The temperature of change trend changes between 500 and 600 °C, which fits the normal distribution. The capacitance of loess decreases first and then slowly increases with increased temperature. The temperature of change trend changes between 200 and 300 °C. (2) The experimental results also show that frequency has an important effect on the measurement of electrical parameters. As the frequency increases, the resistance, capacitance, and impedance decrease. In addition, at high frequencies, the electrical properties of loess are basically not affected by temperature. Therefore, using a frequency of 100 Hz is more advantageous to study the variation law of the electrical properties of loess.

Optimization of factors influencing temperature rise and thermal necrosis of a robot driven piezoelectric osteotomy in bovine cortical bone: An in vitro study using an orthogonal test design

BACKGROUND

This study aimed to provide a comprehensive investigation into factors influencing the thermal effect in robot assisted osteotomies utilizing a piezoelectric osteotome and to identify an optimal combination of factors that minimize the thermal effect in an orthogonal experimental design.

METHODS

Fresh bovine cortical bone was cut under standardized conditions using a robot arm, a piezoelectric osteotome, and a cooling system. Temperature was monitored and the histological depth of osteocyte thermal necrosis was examined to quantify the thermal effect(s). Eighteen experimental trials were conducted according to the standard L18 (2¹ × 3⁷) orthogonal design table to explore the roles of 6 factors: power of the piezoelectric osteotome, cutting depth, cutting speed, coolant type, coolant flow velocity, and coolant temperature.

FINDINGS

Our data showed that coolant flow velocity, coolant temperature and cutting speed significantly influenced temperature (p < .05), while no significant temperature increase was identified relating to cutting depth, power of the piezoelectric osteotome and coolant type. The findings of histological osteocyte thermal necrosis correlated with the results of the temperature change.

INTERPRETATION

Coolant flow velocity, coolant temperature and cutting speed were key factors influencing the thermal impact of the piezoelectric osteotome. With proper combination of these 3 factors, a piezoelectric osteotome is safe to use from a thermal perspective.

Fluorescence quantum yield of natural dye extracted from Tradescantia pallida purpurea as a function of the seasons: Preliminary bioapplication as a fungicide probe for necrotrophic fungi

In this work, over the course of four seasons (12 months), we have monitored the fluorescence quantum efficiency (η) from two sets (S1 and S2) of fresh natural dye extracts from the leaves of Tradescantia pallida purpurea. The natural dye was extracted in aqueous solutions from leaves collected from regions with a predominance of shade (S1) and sun (S2) during the day. The thermo-optical parameter fractional thermal load (φ) was measured using conical diffraction (CD) patterns caused by thermally driven self-phase modulation, for η determination in both sets of solutions. Fluorescence measurements corroborate the CD results, and the η values are, on average, slightly higher (~ 11%) in the summer than in the other seasons for both sets of samples (S1 and S2). In addition, the experimental results are presented using natural dye extracted from Tradescantia pallida purpurea as a fungicide probe in Fusarium solani, Sclerotinia sclerotiorum, and Colletotrichum gloeosporioides fungi. The promising fungicide results obtained for the aqueous natural dye extract were compared with those obtained for other natural dyes and fungi. The fungi tested are of the necrotrophic group and constitute important pathosystems in Brazil, causing diseases in several crops that synthetic fungicides often cannot control or do so with low efficiency.

Thermal behaviors and harmful volatile constituents released from asphalt components at high temperature

Asphalt binder releases lots of heat and harmful volatiles at high temperature. To further understand thermal behaviors, dynamic release and toxic constituents of emitted volatiles during the combustion of asphalt binder, such fractions as saturates, aromatics, resins and asphaltenes (SARA) were first prepared. Thermal behaviors, volatile constituents and combustion residue microstructures of SARA fractions are discussed. Results indicate that polymerization degree of asphalt binder is high and the content of polycyclic aromatic compounds is large. Combustion processes of resins and asphaltenes only show single-stage exothermic reactions, but other two fractions present obvious multi-stage combustion reactions. As the heating rate is raised, the incomplete combustion of SARA fractions is increased, and more volatiles are released. Main volatiles released from SARA fractions are inflammable, toxic, corrosive or explosive compounds, and such common volatiles as acetaldehyde and propane are released from each SARA fraction. More toxic volatiles are released at combustion stage I, but macromolecular volatiles are mainly released at stage II. Volatile release behaviors of saturates and aromatics are more obviously affected by the heating rate. Combustion residues show more intact morphologies from saturates to asphaltenes, and mainly contain C, O and S elements. Asphalt binder is hazardous material at high temperature.

Thermal effects of the Thunderbeat™ device on the recurrent laryngeal nerve during thyroid surgery

PURPOSE

To investigate the safety of the Thunderbeat^™ (TB) device in thyroid surgery by clarifying its thermal effects on the recurrent laryngeal nerve (RLN).

METHODS

We performed thyroidectomy using TB on four female pigs under general anesthesia. TB was applied 0, 1, and 2 mm from the RLN. The effects of incisions made in tissues in the vicinity of the RLN were evaluated by intraoperative neuromonitoring and pathological examination.

RESULTS

The value of the neural integrity monitor (NIM) was unchanged at 2 and 1 mm, but there was loss of signal at 0 mm. The differences between 2 and 0 mm were not clear from the pathological findings.

CONCLUSIONS

When using the TB device during thyroid surgery, it is recommended that it is visually kept from making any contact with the RLN.

Thermal effects on arsenic emissions during coal combustion process

In this study, the rate of emission of arsenic during the burning process of different kinds of coal is examined in order to study the volatile characteristics of arsenic during coal combustion which have negative effects on the ecological environment and human health. The results show that the emission rate of arsenic gradually increases with increased burning temperature, with a threshold of approximately 700°C to 800°C in the process of temperature increase. Then, the relationships among the arsenic emission rate and combustion environment, original arsenic content, combustion time, burning temperature, air flow and amount of arsenic fixing agent are discussed, and it is found that except for the original arsenic content, the rest of the factors have a nonlinear relationship with the emission rate of arsenic. That is, up to a certain level, they all contribute to the release of arsenic, and then their impact is minimal. The original arsenic content in coal is proportional to the arsenic emission rate. Therefore, taking into consideration the nonlinear relationships between factors that affect the arsenic emission rate can reduce contamination from arsenic.

Observation of an improved healing process in superficial skin wounds after irradiation with a blue-LED haemostatic device

The healing process of superficial skin wounds treated with a blue-LED haemostatic device is studied. Four mechanical abrasions are produced on the back of 10 Sprague Dawley rats: two are treated with the blue-LED device, while the other two are left to naturally recover. Visual observations, non-linear microscopic imaging, as well as histology and immunofluorescence analyses are performed 8 days after the treatment, demonstrating no adverse reactions neither thermal damages in both abraded areas and surrounding tissue. A faster healing process and a better-recovered skin morphology are observed: the treated wounds show a reduced inflammatory response and a higher collagen content. Blue LED induced photothermal effect on superficial abrasions.

Brain Surface Heating After Exposure to Ultrasound: An Analysis Using Thermography

Ultrasound is the imaging modality of choice to monitor brain pathologies in neonates after complicated deliveries. Animal studies have indicated that ultrasound may cause heating of brain tissues. To date, no study has explored brain surface heating by ultrasound during clinically relevant exposure. Hence, we investigated heating effects of B-mode and pulsed Doppler (PD) mode on ex vivo lamb brains using thermography. Five brains were scanned for 5 min in B-mode or for 3 min, 1 min, 30 s or 15 s in PD mode. Brain surface temperature was measured pre- and post-exposure using thermography. The highest mean temperature increase was recorded by B-mode (3.82 ± 0.43°C). All five PD exposure protocols were associated with surface temperature increases of 2.1-2.7°C. These outcomes highlight for the first time that B-mode ultrasound can contribute to brain surface heating during a routine cranial scan. Scan duration should be minimised whenever possible.

Wide-aperture TeO₂ AOTF at low temperatures: operation and survival

The effect of temperature on the performance in a wide-angle paratellurite acousto-optic tunable filter (AOTF) is analyzed on the example of two different AOTF configurations. The present study is a by-product of the AOTF characterization for space-borne applications. The two AOTFs serve as dispersion elements in spectrometers for Moon and Mars space missions. The operation of the AO filters was tested in the range of -50° to+40°C; we have also demonstrated the survival of an AOTF device at -130°C. The phase matching ultrasound frequency varies with temperature within 2.5×10(-5) K(-1) and 6.6×10(-5) K(-1). We link this temperature shift to elastic characteristics of the TeO2, and demonstrate that it is mostly explained by the temperature modification of the slow acoustic wave velocity. We point out the best reference describing experimental results (Silvestrova et al., 1987). A generalization is made for all wide-angle acousto-optic tunable filters based on tellurium dioxide crystal.

Synthesis and spectroscopic characterization of a fluorescent pyrrole derivative containing electron acceptor and donor groups

The synthesis and fluorescence characterization of a new pyrrole derivative (PyPDG) containing the electron donor-acceptor dansyl substituent is reported. The effects of temperature and solvent polarity on the steady-state fluorescence of this compound are investigated. Our results show that PyPDG exhibits desirable fluorescent properties which makes it a promising candidate to be used as the photoactive material in optical thermometry and thermography applications. Further, the electrochemical and emission properties of polymeric films obtained from the oxidation polymerization of PyPDG are also analyzed.

Impact of thermal effects induced by ultrasound on viability of rat C6 glioma cells

In order to have consistent and repeatable effects of sonodynamic therapy (SDT) on various cancer cells or tissue lesions we should be able to control a delivered ultrasound energy and thermal effects induced. The objective of this study was to investigate viability of rat C6 glioma cells in vitro depending on the intensity of ultrasound in the region of cells and to determine the exposure time inducing temperature rise above 43 °C, which is known to be toxic for cells. For measurements a planar piezoelectric transducer with a diameter of 20 mm and a resonance frequency of 1.06 MHz was used. The transducer generated tone bursts with 94 μs duration, 0.4 duty-cycle and initial intensity ISATA (spatial averaged, temporal averaged) varied from 0.33 W/cm(2) to 8 W/cm(2) (average acoustic power varied from 1 W to 24 W). The rat C6 glioma cells were cultured on a bottom of wells in 12-well plates, incubated for 24h and then exposed to ultrasound with measured acoustic properties, inducing or causing no thermal effects leading to cell death. Cell viability rate was determined by MTT assay (a standard colorimetric assay for assessing cell viability) as the ratio of the optical densities of the group treated by ultrasound to the control group. Structural cellular changes and apoptosis estimation were observed under a microscope. Quantitative analysis of the obtained results allowed to determine the maximal exposure time that does not lead to the thermal effects above 43 °C in the region of cells for each initial intensity of the tone bursts used as well as the threshold intensity causing cell death after 3 min exposure to ultrasound due to thermal effects. The averaged threshold intensity was found to be about 5.7 W/cm(2).

Benefits and risks of ultrasound in pregnancy

Ultrasound is, arguably, the most commonly used diagnostic procedure in obstetrics. It is convenient, painless, yields immediate, extensive results, and is widely considered to be safe. Some (but not all) benefits described in the literature have been validated by evidence-based analysis, such as pregnancy dating. Others are considered clinically useful, although objective evidence may be less strong. As is the case with almost any medical procedure, however, its performance carries some risks: misdiagnosis on the one hand and possible undesired effects on the other. The general belief exists that diagnostic ultrasound (DUS) does not pose any risk to the pregnant patient nor to her fetus. Nonetheless, ultrasound is a form of energy and, as such, demonstrates effects in biological tissues it traverses (bioeffects). The physical mechanisms responsible for these effects are thermal or non-thermal (mechanical). It is the role of science to show whether any of these bioeffects may be harmful. A risk-benefit analysis may also be important, as well as education of the end users to assure patients' safety.

Temperature prediction in high speed bone grinding using motor PWM signal

This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application.