Development Of New Light Sources Research Articles

Characteristics of bilirubin photochemical changes under green light-emitting diodes in humans compared with animal species

Phototherapy using light-emitting diodes (LEDs) centered on the green spectrum, which has a high cyclobilirubin production rate, was as effective as that centered on the blue spectrum for neonatal hyperbilirubinemia. There are no reports of species differences in bilirubin photochemical changes in this spectrum, and the characteristics of bilirubin photochemical changes in humans must be elucidated to proceed with the development of new light sources that include these spectra. This report describes the characteristic photochemical kinetics of bilirubin under green-spectrum LEDs in human, rat, rabbit, dog, pig, sheep, bovine and chicken serum albumin and rhesus monkey serum. These albumin-bilirubin complex solutions were irradiated by green LEDs, and the time-course changes in bilirubin photoisomers were measured by high-performance liquid chromatography. The cyclobilirubin production rates in humans, pigs, and monkeys were significantly higher than those in other species. The rate constant of (EZ)-cyclobilirubin production from (EZ)-bilirubin ‘k’ was significantly higher in humans and monkeys than in other species. In conclusion, bilirubin photochemical kinetics under green spectrum LEDs in humans were characterized by a high cyclobilirubin production rate at a low substrate concentration. The bilirubin photochemical kinetics in monkeys were similar to those in humans.

Preface to Special Issue on Development of New Light Sources and Elements Technology for Next-Next-Generation Laser Processing

Preface to Special Issue on Development of New Light Sources and Elements Technology for Next-Next-Generation Laser Processing

C60 fullerene accumulation in human leukemic cells and perspectives of LED-mediated photodynamic therapy

Recent progress in nanobiotechnology has attracted interest to a biomedical application of the carbon nanostructure C60 fullerene since it possesses a unique structure and versatile biological activity. C60 fullerene potential application in the frame of cancer photodynamic therapy (PDT) relies on rapid development of new light sources as well as on better understanding of the fullerene interaction with cells.The aim of this study was to analyze C60 fullerene effects on human leukemic cells (CCRF-CEM) in combination with high power single chip light-emitting diodes (LEDs) light irradiation of different wavelengths: ultraviolet (UV, 365 nm), violet (405 nm), green (515 nm) and red (632 nm). The time-dependent accumulation of fullerene C60 in CCRF-CEM cells up to 250 ng/106 cells at 24 h with predominant localization within mitochondria was demonstrated with immunocytochemical staining and liquid chromatography mass spectrometry. In a cell viability assay we studied photoexcitation of the accumulated C60 nanostructures with ultraviolet or violet LEDs and could prove that significant phototoxic effects did arise. A less pronounced C60 fullerene phototoxic effect was observed after irradiation with green, and no effect was detected with red light. A C60 fullerene photoactivation with violet light induced substantial ROS generation and apoptotic cell death, confirmed by caspase3/7 activation and plasma membrane phosphatidylserine externalization. Our work proved C60 fullerene ability to induce apoptosis of leukemic cells after photoexcitation with high power single chip 405 nm LED as a light source. This underlined the potential for application of C60 nanostructure as a photosensitizer for anticancer therapy.

Photometric Absorbance Spectrum Analyzer of Slightly Transparent Biomaterials

Introduction. The measurement of optical radiation, especially the intensity of the light flux passing through biological tissues or other slightly transparent (cloudy) materials and the environments is a challenging problem due to the extensive development of new light sources of different wavelengths and their use in various fields of human activity. It is important to provide high sensitivity and accuracy measurement of the output parameters of light fluxes passing through the studied material - the depth of penetration, attenuation coefficient or absorption. The known methods and devices do not provide the required sensitivity and accuracy of measuring parameters. Main body. The aim of this study is to develop a photometric spectrum analyzer where along with the simplification of the scheme and increasing sensitivity and measurement accuracy the score of penetration depth of light flux into biological or other slightly transparent material, the determination of the attenuation coefficient and the spectrogram construction based on the analysis of two signals separated by wavelength light sources is ensured. One of the ways to increase the sensitivity and accuracy of the measurement devices is to use modulating method of the output signals transformation. Implementation of this method provides a significant reduction of the proper noises of the transformation signal path. Figure 1 shows a functional diagram of the developed by the authors device based on modulating transformation of the optical signal. It provides the measurement of the slightly transparent materials absorbance with increasing sensitivity and accuracy. Conclusions. Considered possibilities greatly simplify the measurement process. The use of the modulating transformation of the light flux provides increase in sensitivity in the measurement accuracy because such transformation compensates the intrinsic noise level and noise of the measurement channel. The semiconductor matrix is used as the light source. It provides accommodation of two crystals at one point of light diodes with the most spaced wavelengths allowing them to be placed on the same axis with photocell and excludes collateral scattering of the light flux.

In Vitro Photoirradiation System for Simultaneous Irradiation with Different Light Doses at a Fixed Temperature.

In this work an irradiance and temperature controlled in-vitro system for conducting investigations in PDT and phototherapy is presented. The development of new light sources has caused a considerable increase in research and application of several photodynamic (PDT) therapeutic methods, as well as other light-based therapeutic techniques. However, further work is needed to fully understand and elucidate the mechanisms as well as to increase the effectiveness of PDT. Nowadays, there are no commercial systems to perform automated light exposure experiments with cultured cells. Also, there are very few reports of similar photoirradiation systems. The system is composed of 24 independent light-emitting diodes that can be used to irradiate separate wells in a microwell plate. The system includes a module to measure changes in temperature within each irradiated well without contact. The light sources are placed on a plate that can easily be changed in order to irradiate at different wavelengths. The performance of the system is fully controlled with a computer, and all the experimental data are properly recorded. The design, construction, operation, and a full characterization of the system are presented. A novel fully automated photoirradiation system has been developed. The system allows the design of the experiments in this area with precise dosimetry, temperature, and irradiation regime controls reducing manipulation of the samples and saving time.

Efficient 10-Fold Upconversion through Steady-State Non-Thermal-Equilibrium Excitation

Frequency up-conversion of a few low-energy photons into a single high-energy photon contributes to imaging, light sources, and detection. However, the up-converting of many photons exhibits negligible efficiency. Up-conversion through laser heating is an efficient means to generate energetic photons, yet the spectrally broad thermal-emission and the challenge of operating at high temperatures limit its practicality. Heating specific modes can potentially generate narrow up-converted emission; however, so far such "hot-carriers" have been observed only in down-conversion processes and as having a negligible lifetime, due to fast thermalization. Here we experimentally demonstrate up-conversion by excitation of a steady-state non-thermal-equilibrium population, which induces steady, narrow emission at a practical bulk temperature. Specifically, we used a 10.6um laser to generate 980nm narrow emission with 4% total efficiency and up-converted radiance that far exceeds the device s possible black-body radiation. This opens the way for the development of new light sources with record efficiencies.

Optical coherence tomography for the diagnosis of cervical intraepithelial neoplasia

Optical coherence tomography (OCT) permits high-resolution imaging of tissue subsurfaces up to 2 mm in depth. The purpose of this study was to evaluate the accuracy and reproducibility of OCT in the characterization of cervical intraepithelial neoplasia (CIN) and to distinguish between different CIN grades. Colposcopy-guided OCT images were taken from unsuspicious and suspicious areas in women with suspected CIN. Each woman then underwent directed biopsies. All OCT images were separately evaluated by two blinded investigators and later compared to the corresponding histology based on a 6-grade classification (normal, inflammation, CIN 1, CIN 2, CIN 3, squamous carcinoma). Sensitivity and specificity of OCT in detecting CIN were determined. To assess the interobserver agreement, kappa coefficients were calculated from the ratings of each investigator for each OCT image seen. A total of 210 OCT images were compared with the corresponding histology in 120 women undergoing colposcopy for suspected CIN. Sensitivity calculated for both investigators was 98% and 96% respectively with the threshold at CIN1 and 86% and 84% respectively with the threshold at CIN2. Thirty nine (38) false positive results reduced the specificity to 39% and 41% respectively with the threshold at CIN1. Defining the threshold at CIN2 the specificity increased to 64% and 60% respectively. Unweighted kappa from a dichotomous classification with the threshold at CIN1 was 0.69 (95% CI, 0.54-0.84) and 0.62 (95% CI, 0.51-0.73) with the threshold at CIN2. OCT is highly sensitive in identifying pre-invasive and invasive cancer of the uterine cervix. Improvements in resolution and the development of new light sources and optics may improve the specificity as well as the differentiation of cervical dysplasia. The interobserver agreement was substantial.

X-ray race

The development of new light sources and focusing techniques suggests that ultrafast X-ray microscopy is poised to impact numerous fields of science.

Mitochondrial function in vivo evaluated by NADH fluorescence: from animal models to human studies

Normal mitochondrial function is a critical factor in maintaining cellular homeostasis in various organs of the body. Due to the involvement of mitochondrial dysfunction in many pathological states, the real-time in vivo monitoring of the mitochondrial metabolic state is crucially important. This type of monitoring in animal models as well as in patients provides real-time data that can help interpret experimental results or optimize patient treatment. The goals of the present review are the following: 1) to provide an historical overview of NADH fluorescence monitoring and its physiological significance; 2) to present the solid scientific ground underlying NADH fluorescence measurements based on published materials; 3) to provide the reader with basic information on the methodologies used in the past and the current state of the art fluorometers; and 4) to clarify the various factors affecting monitored signals, including artifacts. The large numbers of publications by different groups testify to the valuable information gathered in various experimental conditions. The monitoring of NADH levels in the tissue provides the most important information on the metabolic state of the mitochondria in terms of energy production and intracellular oxygen levels. Although NADH signals are not calibrated in absolute units, their trend monitoring is important for the interpretation of physiological or pathological situations. To understand tissue function better, the multiparametric approach has been developed where NADH serves as the key parameter. The development of new light sources in UV and visible spectra has led to the development of small compact units applicable in clinical conditions for better diagnosis of patients.

Vacuum-UV (172 nm) Actinometry. The Quantum Yield of the Photolysis of Water

With the development of new light sources (Xe-excimer light sources), the vacuum-UV (VUV) photochemistry on a preparative scale is becoming technically feasible. Among the first potential technical applications, VUV photolysis of aqueous systems must be considered as a potential alternative to established “advanced oxidation procedures” (AOP). For the design and dimensioning of corresponding reactors, incident photon rates must be determined. The standard VUV actinometry in condensed phase is the cis−trans isomerization of cyclooctene in n-pentane. The incident photon rate of these new light sources depends on their geometry, the configuration of their electrodes, and the dielectric constant of the solvent in the case where the substrate solution is part of the dielectric barrier; thus actinometric experiments should be made under operational conditions. However, the radiant power density of the excimer sources will be different if n-pentane (standard actinometry) is used as part of the dielectric barrier...

Second Order Nonlinear Optics: from Fundamentals to Applications

This topical issue of Quantum and Semiclassical Optics contains a series of articles presented at the workshop ` Second Order Nonlinear Optics: from Fundamentals to Applications', held in l'Ecole de Physique des Houches (Haute-Savoie, France) from 22 to 26 April 1996. The recent development of new laser sources, such as diode-pumped solid-state lasers, and the availability of new highly nonlinear materials (including artificial materials based on quasi-phase-matched techniques) has induced a revival of the field of second order nonlinear optics. This research covers a broad spectrum, ranging from fundamentals (generation of nonclassical states of light, amplification without added noise, frequency division chain, etc.) to applications (spectroscopy, teledetection, metrology, communications, etc.), through the development of new light sources (coherent and tunable, pulsed or continuous wave) and of new optronic devices.

A New Generation of Metal Halide Lamps

The continuing study of high-intensity discharge (HID) light sources has focussed attention on the convective gas flows within the arc tube. The arc tube wall temperature as affected by the transport gases has also been investigated. The knowledge and data obtained from these observations yield concepts leading to the development of new light sources that show superior performance characteristics over equivalent models of contemporary metal halide lamps. For a better understanding of these concepts, this paper reviews the phenomena within the arc from the time of ignition until the discharge is stabilized.