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Measurement of ROS in Caenorhabditis elegans Using a Reduced Form of Fluorescein
摘要： Oxidative stress is implicated in the pathogenesis of various neurodegenerative diseases, including Alzheimer’s disease. Oxidative stress is a result of a disruption of the equilibrium between antioxidants and oxidants, in favor of oxidants. Since mitochondria are major sites of production and reduction of reactive oxygen species (ROS), measurement of ROS levels can help us determine if mitochondrial functional integrity has been compromised. In this protocol, we describe a method to measure the level of ROS in the nematode Caenorhabditis elegans, using chloromethyl-2,7’-dichlorodihydrofluorescein diacetate (CM-H2DCFDA).
关键词： CM-H2DCFDA,C. elegans,Mitochondria,Oxidative stress,DCF,ROS
更新于2025-09-19 17:15:36
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Analysis of Residual Stress in Electrical Penetration Assembly Based on a Fiber Bragg Grating Sensor
摘要： An important factor for maintaining hermeticity of a metal-to-glass sealed electrical penetration assembly (EPA) is the residual stress in the sealing glass, which is generated during the EPA sealing process. A novel method to investigate and optimize the sealing process of EPAs, based on a fiber Bragg grating (FBG) sensor, is proposed in this research. An FBG was well bonded with sealing glass to measure the parameters of the glass during the sealing process. The temperature change during the heating process was able to be measured by Bragg wavelength shift. After the sealing glass solidified and dropped to room temperature, the residual stress was determined and the effect of temperature was minimized because the temperature before and after the sealing process was the same as room temperature. The curing temperature of the sealing glass was evaluated to specifically investigate the solidification process of the EPA. This study provides a basis for online stress and temperature monitoring of EPAs under external loads in nuclear power plants.
关键词： electrical penetration assembly,embeddable technology,sealing process analysis,residual stress,fiber Bragg grating
更新于2025-09-19 17:15:36
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Transient thermoelastic response in a cracked strip of functionally graded materials via generalized fractional heat conduction
摘要： This work is devoted to analyzing a thermal shock problem of an elastic strip made of functionally graded materials containing a crack parallel to the free surface based on a generalized fractional heat conduction theory. The embedded crack is assumed to be insulated. The Fourier transform and the Laplace transform are employed to solve a mixed initial-boundary value problem associated with a time-fractional partial differential equation. Temperature and thermal stresses in the Laplace transform domain are evaluated by solving a system of singular integral equations. Numerical results of the thermoelastic fields in the time domain are given by applying a numerical inversion of the Laplace transform. The temperature jump between the upper and lower crack faces and the thermal stress intensity factors at the crack tips are illustrated graphically, and phase lags of heat flux, fractional orders, and gradient index play different roles in controlling heat transfer process. A comparison of the temperature jump and thermal stress intensity factors between the non-Fourier model and classical Fourier model is made. Numerical results show that wave-like behavior and memory effects are two significant features of the fractional Cattaneo heat conduction, which does not occur for the classical Fourier heat conduction.
关键词： functionally graded materials,thermal stress,crack,time-fractional heat conduction,phase lag of heat flux
更新于2025-09-19 17:15:36
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The Effect of Fluence on Macrophage Kinetics, Oxidative Stress, and Wound Closure Using Real-Time <i>In Vivo</i> Imaging
摘要： Objective: The aim of our study was to quantify the effect of doses delivered by a He:Ne laser on individual macrophage kinetics, tissue oxidative stress, and wound closure using real-time in vivo imaging. Background: Photobiomodulation has been reported to reduce tissue inflammation and accelerate wound closure; however, precise parameters of laser settings to optimize macrophage behavior have not been established. We hypothesized that quantitative and real-time in vivo imaging could identify optimal fluence for macrophage migration, reduction of reactive oxygen species, and acceleration of wound closure. Methods: Larval zebrafish Tg(mpeg-dendra2) were loaded with dihydroethidium for oxidative stress detection. Fish were caudal fin injured, treated with 635 nm continuous 5 mW He:Ne laser irradiation at 3, 9, or 18 J/cm2 and time-lapsed imaged within the first 120 min postinjury. Images taken 1 and 24-h postinjury were compared for percentage wound closure. Results: A fluence of 3 J/cm2 demonstrated significant increases in macrophage migration speed, fewer stops along the way, and greatest directed migration toward the wound. These findings were associated with a significant reduction in wound content reactive oxygen species when compared with control wounded fins. Both 3 and 9 J/cm2 significantly accelerated wound closure when compared with nonirradiated control fish. Conclusions: Wound macrophage activity could be manipulated by applied fluence, leading to reduced levels of wound reactive oxygen species and accelerated wound closure. The zebrafish model provides a means to quantitatively compare wound macrophage behavior in response to a variety of laser treatment parameters in real time.
关键词： zebrafish,macrophage,He:Ne laser,oxidative stress,time-lapse imaging
更新于2025-09-19 17:15:36
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An Experimental Study on Infrared Radiation Characteristics of Sandstone Samples Under Uniaxial Loading
摘要： The failure of surrounding strata in the excavation faces is the root cause of some disasters, including roof caving, coal pillar instability, and water inrushes, during the extraction of coal resource. Identifying the abnormal phenomena and precursor information before rock failure forms an important theoretical foundations of achieving safety operation in coal mines. The infrared radiation (IR) on the surface of rock will change during loading process (Luong 1990; Freund et al. 2007; Gong 2013). By monitoring the IR, the deformation and failure characteristics of rock can be obtained (Sheinin and Blokhin 2012; Mineo and Pappalardo 2016; Sun et al. 2017; Fiorucci et al. 2018), reliable information for predicting rock failure precursors may be obtained, as well (Wu et al. 2015; Salami et al. 2017). In addition, the water content affects the IR characteristics during the failure of rock (Liu et al. 2010). To quantitatively characterize the IR from the rock surface during loading process, Wu (1998) first proposed the index of average infrared radiation temperature (AIRT). Later, Liu et al. (2015), Yang et al. (2017) and Ma et al. (2016) proposed new indexes for quantitative analysis, e.g., variance, entropy, characteristic roughness, euclidean distance, and VDIIT. The previous experimental results revealed that these new indexes could be used to explain a lot of IR phenomena during rock failure (Pappalardo 2017; Zhang et al. 2018). For example, the author have investigated the inherent relation between stress and IR during rock loading (Ma et al. 2017), and found that stress had significant, universal, and hysteretic control effects on IR. However, there are still difficulties during the acquisition of IR mutation data and the estimation of mutation amplitude under loading conditions. Therefore, new appropriate indexes should be proposed for more accurate determination of the quantitative relation between stress and IR. To further investigate the relation between stress and IR, two mutation coefficients, stress rate (SR) and variance of differential infrared image temperature (VDIIT), were adopted in this study. The related IR observation experiments were conducted using samples with different water content, so as to obtain the quantitative relation between stress and IR under uniaxial loading tests.
关键词： Stress rate (SR),Infrared radiation (IR),Control effect,Variance of differential infrared image temperature (VDIIT),Mutation coefficient
更新于2025-09-19 17:15:36
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Stress Relaxation in Porous GaN Prepared by UV Assisted Electrochemical Etching
摘要： This study describes the stress relaxation in porous GaN grown on Al2O3 substrates. The results indicate that the stress relaxation has taken place in the samples which increases by increasing the etching current. As compared to the as-grown GaN films, porous GaN exhibits substantial photoluminescence (PL) intensity enhancement with red-shifted band-edge peaks associated with the relaxation of the compressive stress. The red shifted phonon energy peak (E2) in the Raman spectra of the porous GaN films confirms further such a stress relaxation. Scanning electron microscopy (SEM) demonstrates that, the current density has significant effect on the size and shape of the pores.
关键词： Stress relaxation,Porous GaN,Raman spectroscopy,Red shift
更新于2025-09-19 17:15:36
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Mechanical stress dependence of the Fermi level pinning on an oxidized silicon surface
摘要： A combination of micro-Raman spectroscopy and micro-XPS (X-ray photo-electron spectroscopy) mapping on statically deflected p-type silicon cantilevers is used to study the mechanical stress dependence of the Fermi level pinning at an oxidized silicon (001) surface. With uniaxial compressive and tensile stress applied parallel to the ?110? crystal direction, the observations are relevant to the electronic properties of strain-silicon nano-devices with large surface-to-volume ratios such as nanowires and nanomembranes. The surface Fermi level pinning is found to be even in applied stress, a fact that may be related to the symmetry of the Pb0 silicon/oxide interface defects. For stresses up to 240 MPa, an increase in the pinning energy of 0.16 meV/MPa is observed for compressive stress, while for tensile stress it increases by 0.11 meV/MPa. Using the bulk, valence band deformation potentials the reduction in surface band bending in compression (0.09 meV/MPa) and in tension (0.13 meV/MPa) can be estimated.
关键词： Mechanical stress,Raman spectroscopy,X-ray photoelectron spectroscopy,Surface Fermi level pinning,Silicon,Interface defect
更新于2025-09-19 17:15:36
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Irradiation effects of swift heavy ions on palladium films deposited on 6H-SiC substrate
摘要： The irradiation effect of swift heavy ions on palladium (Pd) films deposited on 6H-SiC was investigated. The samples were irradiated by Xe26+ ions with the energy of 167 MeV at fluences of 1 × 1013 cm?2 and 3 × 1014 cm?2 at room temperature. Phase identification, residual stress and surface morphology were investigated with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results showed that the as-deposited sample was composed of Pd and SiC with no evidence of a reaction between Pd and SiC. No reaction was observed for the lower irradiation fluence, only an increase in the Pd peak intensities was observed indicating improvement in the crystallinity of the material. A reaction between Pd and SiC forming PdSi and Pd2Si was observed after irradiation at a fluence of 3 × 1014 cm?2. The stress measurements indicated that the films were having tensile and biaxial stress not exceeding 200 MPa. A decrease in stress values was observed with an increase in irradiation fluence. The surface morphology of the as-deposited was flat and composed of small granules. There was an increase in granule sizes due to irradiation at 1 × 1013 cm?2. Irradiating at 3 × 1014 cm?2 caused grain agglomeration and clustering.
关键词： Palladium,SiC,Swift heavy ions,Stress,Irradiation
更新于2025-09-19 17:15:36
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[ACM Press the 2018 International Conference - Prague, Czech Republic (2018.10.12-2018.10.14)] Proceedings of the 2018 International Conference on Sensors, Signal and Image Processing - SSIP 2018 - Constrained Attribute Selection for Stress Detection Based on Physiological Signals
摘要： We present a constrained attribute selection method that makes use of feature assessment based on the Fisher’s separation criterion followed by variety reduction post-processing. The post-processing incorporates task-specific constrain into the feature selection process, as this is expected to facilitate the subsequent data modeling and classification stages. Here we validate the proposed method in an experimental setup oriented towards acute stress detection based on physiological signals. The experimental results support that the proposed method brings advantage, when compared to three other cases: (i) the full set of features, (ii) a subset selected based on prior knowledge, (iii) and a subset selected based solely on Fisher’s separation criterion.
关键词： Fisher linear discriminant,Stress detection,Attribute selection,Electrocardiography (ECG),Galvanic skin response (GSR)
更新于2025-09-19 17:15:36
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Variations of the elastic modulus perpendicular to the surface of rubrene bilayer films
摘要： Investigations exploring the inherent mechanical properties of electronic materials have grown rapidly in recent years largely because they are important in developing flexible electronics, organic displays and sensors. However, our understanding of the mechanical properties of organic semiconductors with a thin-film form remains limited. We report herein on an investigation of the structures and related elastic moduli perpendicular to the surface of a rubrene thin film. A rubrene/Si(100) film typically has a cluster-type morphology mainly comprised of crystalline nanodomains within the film. We propose a structural bilayer model that can be used to explain the layered nature or characteristics of the rubrene films. As the film thickness is increased, the enhancement in elastic modulus can be attributed to the presence of a soft surface layer on a hard underlayer. Based on four-point probe measurements, the bilayered nature of such materials can be used to characterize their electrical resistive behavior while interfacial roughness is sensitive to the transport paths of conduction electrons. This information is valuable for future applications of organic semiconductors in flexible devices.
关键词： four-probe measurement,atomic force microscopy,rubrene,stress
更新于2025-09-19 17:15:36