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Photodynamic Therapy at Low-Light Fluence Rate: in vitro Assays on Colon Cancer Cells
摘要： This paper presents the results of in vitro photodynamic therapy assays on RKO and HCT-15 cell lines. The envisaged implementation is in autonomous medical microdevices, such as endoscopic capsules for clinical treatment of several types of gastrointestinal tract tumors. Because of their very limited device volume, light fluence and fluence rate needed to destroy tumor cells should be minimized. Foscan or meta-tetra(hydroxyphenyl)chlorin (mTHPC) is used as a photosensitizer. The experimental results show that a small amount of mTHPC (0.15 mg/kg) and light fluence (5–20 J/cm2) is sufficient to obtain significant photodynamic activity. An array of LEDs with peak transmittance at 652 nm is used as a portable light source for the maximum quantum efficiency in producing singlet oxygen. Irradiation to a light fluence between 2.5 and 10 J/cm2 is achieved by an increased exposure time at an 11 mW/cm2 light fluence rate, while mTHPC concentrations of 0.5, 1, 5, and 10 μg/mL are used. The experimental results show that decreased cell viability (down to 30%) can be obtained for 1–5 μg/mL of mTHPC concentrations and 2.5 J/cm2 of light fluence. Such light fluence and light fluence rate are compatible with the endoscopic capsules batteries.
关键词： Biophotonic therapeutic technique,Photodynamic therapy,light-tissue interaction
更新于2025-09-23 15:22:29
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Dual tree complex wavelet transform incorporating SVD and bilateral filter for image denoising
摘要： In recent years massive production of digital images increased the need for image denoising. The effect of noise can be removed by using spatial and frequency domain approaches. Discrete Wavelet Transforms (DWT) is a frequency domain approach, which removes the noise by shrinking the wavelet coefficients using simple threshold value. Even though wavelet transform is popularly used in image processing applications, shift variance and poor directional selectivity are the two noteworthy limitations. In order to overcome these limitations, Dual Tree Complex Wavelet Transform (DTCWT) is used for perfect reconstruction of noisy image. A DTCWT incorporating Singular Value Decomposition (SVD) with Frobenius energy correcting factor and bilateral filter for image denoising using bivariate shrinkage function for thresholding the image is proposed in this paper. The denoising performance of the proposed method in terms of PSNR and it indicates that the proposed method outperforms over other existing techniques.
关键词： bilateral filter,SVD,bivariate shrinkage,thresholding technique,wavelet transform,DTCWT,image denoising
更新于2025-09-23 15:22:29
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The investigation of a new fast timing system based on DRS4 waveform sampling system
摘要： In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excited states. In the paper, we have developed a new fast timing system, which is made up of two LaBr3:Ce detectors and a set of waveform sampling system. The sampling system based on domino ring sampler version 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smaller volume and higher timing accuracy, and the waveform data are performed by means of digital waveform analysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keV g photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in the large dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the t 152Gd-21 decay of 152Eu source is measured. The measured lifetime is 45.3(±5.0)ps, very close to the value of the National Nuclear Data Center (NNDC: 46.2((±3.9)ps). The experimental results indicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, the system can be widely used in the research of the fast timing technology.
关键词： Waveform sampling system,Excited state lifetime,LaBr3:Ce scintilator,Fast timing technique
更新于2025-09-23 15:22:29
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Biosensor for point-of-care analysis of immunoglobulins in urine by metal enhanced fluorescence from gold nanoparticles
摘要： Biosensors are easy-to-use and cost-effective devices that are emerging as an attracting tool not only in settling diagnosis or in disease monitoring, but also in mass screening tests, a timely topic that impacts on daily life of the whole society. Nanotechnologies lend themselves to the development of highly sensitive device whose realization has become a very interdisciplinary topic. Relying on the enhancement of the fluorescence signal detected at the surface of patterned gold nanoparticles, we report the behavior of an analytical device in detecting immunoglobulins in real urine samples that shows a limit of detection of approximately 8 μg/L and a linear range of 10-100 μg/L well below the detection limit of nephelometric method, which is the reference method for this analysis. These performances have been reached thanks to an effective surface functionalization technique and can be improved even more if superhydrophobic features of the substrate we produce will be exploited. Since the analyte recognition is realized by antibodies the specificity is very high and, in fact, no interference has been detected by other compounds also present in the real urine samples. The device has been assessed on serum samples by comparing IgG concentrations values obtained by the biosensor with those provided by a nephelometer. In this step we found that our approach allows the analysis of the whole blood without any pretreatment; moreover, it is inherently extendable to the analysis of most biochemical markers in biological fluids.
关键词： antibody,point-of-care device,nanostructured gold surface,photochemical immobilization technique,gold nanoparticles,metal enhanced fluorescence,biosensors
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Carbon Dioxide and Water Vapour Fluxes of a Alkaline Fen and Their Dependence on Reflectance
摘要： This study shows results of parallel measurements of greenhouse gases fluxes (carbon dioxide and water vapour) and canopy reflectance of alkaline fen. Fluxes were measured using eddy-covariance technique on micrometeorological station located in the Upper Biebrza Basin (NE Poland) in Rogo?ynek Village. Study site is located in the Biebrza National Park which was established to protect one of the biggest coherent lowland wetland area in the Central Europe. Statistical relations of reflectance and spectral indices with fluxes were calculated based on measurements during two growing season (2015 and 2016). Four types of functions were examined: linear, quadratic, exponential and logarithmic and for two timestamps: half-hour and day. The correlation between carbon dioxide fluxes and reflectance is better than for water vapour fluxes. For both carbon dioxide and water vapour we obtained higher correlations coefficients using selected spectral indices than using reflectance and higher correlations for daily timestamp than for half-hour fluxes.
关键词： greenhouse gases,eddy-covariance technique,spectral indices,Biebrza River valley,wetland
更新于2025-09-23 15:22:29
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Thermal Characterization of a PPy/PLA Composite by Photoacoustic Calorimetry and Photopyroelectric Techniques
摘要： Recently, conductive polymers have attracted attention in the field of advanced materials. Conducting polymers include polypyrrole (PPy), which is a material with commercial applications due to its stability and electrical conductivity. As technology demands increasingly flexible devices, PPy was mixed with a biodegradable and flexible polymer, polylactic acid, in order to create a composite possessing of newer properties. As it is a new material, thermal properties of this composite such as thermal diffusivity, thermal effusivity, specific heat capacity, and thermal conductivity have been investigated through the application of photoacoustic calorimetry and photopyroelectric techniques.
关键词： PPy/PLA composite,Photoacoustic calorimetry,Polymer,Photopyroelectric technique
更新于2025-09-23 15:22:29
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A simulation study of field plate termination in Ga <sub/>2</sub> O <sub/>3</sub> Schottky barrier diodes
摘要： In this work, the field plate termination is studied for Ga2O3 Schottky barrier diodes (SBDs) by simulation. The influence of field plate overlap, dielectric material and thickness on the termination electric field distribution are demonstrated. It is found that the optimal thickness increases with reverse bias increasing for all the three dielectrics of SiO2, Al2O3, and HfO2. As the thickness increases, the maximum electric field intensity decreases in SiO2 and Al2O3, but increases in HfO2. Furthermore, it is found that SiO2 and HfO2 are suitable for the 600 V rate Ga2O3 SBD, and Al2O3 is suitable for both 600 V and 1200 V rate Ga2O3 SBD. In addition, the comparison of Ga2O3 SBDs between the SiC and GaN counterpart reveals that for Ga2O3, the breakdown voltage bottleneck is the dielectric. While, for SiC and GaN, the bottleneck is mainly the semiconductor itself.
关键词： field plate,termination technique,Ga2O3,Schottky barrier diode
更新于2025-09-23 15:22:29
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Image-guided study of inter-fraction and intra-fraction set-up variability and margins in reverse semi-decubitus breast radiotherapy
摘要： Background: This study aimed to evaluate the inter-fraction set-up error and intra-fraction motion during reverse semi-decubitus (RSD) breast radiotherapy, and to determine a planning target volume (PTV) margin. Material and methods: Pre- and post-treatment cone-beam computed tomography (CBCT) scans were prospectively acquired at fractions 1, 4, 7, 8, 11, and 14 for 30 patients who underwent RSD breast radiotherapy. Online correction for initial set-up error greater than 5 mm or 2° was performed and post-correction CBCT was acquired. An off-line analysis was performed to quantify initial and residual inter-fraction set-up errors and intra-fraction motion in three-dimensions. Patient inter-fraction errors were analysed for time trends during the course of radiotherapy. PTV margins were calculated from the systematic and random errors. Results: The initial inter-fraction population systematic errors were 1.8–3.3 mm (translation) and 0.5° (rotation); random errors were 1.8–2.1 mm (translation) and 0.3–0.5° (rotation). After online correction, the residual inter-fraction population systematic errors were 1.2–1.8 mm (translation) and 0.3–0.4° (rotation); random errors were 1.4–1.6 mm (translation) and 0.3–0.4° (rotation). Intra-fraction population systematic and random errors were ≤ 1.3 mm (translation) and ≤ 0.2° (rotation). The magnitude of inter-fraction set-up errors in the anterior-posterior direction, roll, and yaw were significantly correlated with higher body weight and body mass index (BMI). The inter-fraction set-up error did not change significantly as a function of time during the course of radiotherapy. The magnitude of intra-fraction motion was not correlated with patient characteristics and treatment time. The total PTV margins accounting for pre-correction and intra-fraction errors were 6.5–10.2 mm; those accounting for post-correction and intra-fraction errors were 4.7–6.3 mm. Conclusions: CBCT is an effective modality to evaluate and improve the inter-fraction set-up reproducibility in RSD breast radiotherapy, particularly for patients with higher BMI. Intra-fraction motion was minimal during RSD breast radiotherapy.
关键词： Inter-fraction reproducibility,Intra-fraction motion,Breast radiotherapy,Reverse semi-decubitus technique
更新于2025-09-23 15:22:29
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Electrical Transport Properties of Thin Film Composed of a-ZnO Nanorods
摘要： Background: Due to its wide band gap, high exciton binding energy and high breakdown strength, the nanostructures of ZnO may find applications for electronic, photonic devices, and high-frequency applications. Objective: The aim of the present work is to study electrical transport of thin film composed of a-ZnO nanorods. Method: Physical vapour condensation method was employed to fabricate the nanorods of ZnO. The morphology of these nanorods was investigated with the help of scanning electron microscope. X-ray diffraction pattern of as-prepared thin film was recorded using X-ray diffractometer. For dc conductivity measurements, four-probe method was used. Result: The as-prepared ZnO nanorods have diameter ranging from 10-20 nm and the length is of order of few hundred nanometers. XRD pattern of film composed of ZnO nanorods suggests the amorphous nature. Temperature dependence of dc conductivity has been studied over the temperature range of (297- 4.2K). For the temperature range of 297-120K, Mott’s three dimensional variable range hopping (VRH) is applied to explain the electrical conduction. For lower temperature range (120 - 4.2K), 2D-variable-range hopping in localized states near the Fermi level may be responsible for the transport of carriers. Conclusion: Variable range hopping mechanism (VRH) has been suggested for the entire temperature range (298-4.2K) on the basis of temperature dependence of dc conductivity data, which changes from 3D to 2D on moving to lower temperatures side (below 125K).
关键词： physical vapour condensation technique,variable range hopping,XRD,ZnO nanorods,SEM,Mott’s parameters,electrical conduction mechanism
更新于2025-09-23 15:22:29
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Standardization of <sup>147</sup>Pm by TDCR Liquid Scintillation Counting using Printed Optical Filters; 印刷光学フィルタを用いたTDCR液体シンチレーション計数による<sup>147</sup>Pmの放射能絶対測定;
摘要： The Optical filter method is one of methods to vary the counting efficiency for TDCR (Triple to Double Coincidence) measurement. A method for the fabrication of optical filters for 147Pm standardization was developed using printed plastic film. Toner was printed on a piece of plastic film using the laser printer. The toner color was graduated in steps by a draw software. The counting efficiency was varied according to the amount of scintillation light absorption. The specific activity of 147PmCl3 solution was successfully measured using the printed optical filters.
关键词： TDCR (Triple to Double Coincidence),printing technique,prometium-147,liquid scintillation counting,optical filter
更新于2025-09-23 15:22:29