High-intensity Lamps Research Articles

Effect of preheating and curing lamp distance on the degree of conversion of four nanohybrid resins: An in vitro study.

Inadequate polymerization of resins is a major cause of failure in dental restorations. This study aimed to evaluate the hypothesis that both polymerization distance and preheating of four nanohybrid resins significantly affect their degree of conversion (DC). Four A2-colored nanohybrid resins were selected: Filtek Z250 XT (3M), Tetric N-Ceram (Ivoclar), Zafira (New Stetic), and Spectra Smart (Dentsply). These resins were chosen due to their varied compositions. Forty-eight discs (6 mm diameter, 2 mm thickness) were manufactured, with 24 discs preheated to 39°C. All discs were polymerized for 40 seconds at distances of 1 mm and 6 mm using the Bluephase N lamp (Ivoclar Vivadent), operating at 385-515 nm and 1200 mW/cm². The polymerized discs were stored in distilled water at 37°C for 24 hours, and the DC was measured using Fourier-transform infrared spectroscopy (FTIR). Statistical analysis was performed using one-way ANOVA and independent samples t-tests. No statistically significant differences in DC were observed between samples preheated to 39°C and those at room temperature (p> 0.05). Zafira exhibited the highest DC, significantly higher than Z250 XT in all groups (p< 0.005) and higher than Tetric N-Ceram on the surface (p< 0.05). Significant differences were also found between Zafira and Spectra Smart in specific conditions (p< 0.05). No significant differences in DC were found between polymerization distances of 1 mm and 6 mm. Uniform polymerization was achieved throughout the resin discs. Preheating nanohybrid resins to 39°C had no statistically significant impact on their degree of conversion. Acceptable DC values were achieved using a high-intensity lamp for 40 seconds, even at a curing distance of 6 mm. Among the tested resins, Zafira demonstrated the highest DC under various conditions, significantly outperforming Z250 XT, Tetric N-Ceram, and Spectra Smart in specific comparisons. Key words:Nanohybrid composite, polymerization, degree of conversion.

ОПРОМІНЕННЯ ОВОЧІВ В УМОВАХ ЗАКРИТОГО ҐРУНТУ ДЖЕРЕЛАМИ СВІТЛА З ВИПРОМІНЮЮЧИМИ ДОБАВКАМИ

Purpose. The paper considers peculiarities of using artificial illumination sources with effective spectral composition of radiation for conditions of closed soil. Methodology. High-intensity sodium lamps (DNaT400), high- intensity sources with composition of sodium amalgam with cesium additives were investigated (Hg-20%, Na-7 5%, Cs-5%), potassium (Hg-20%, Na-79%, K-1%). Results. As a result of experiments, it was determined that the spectral radiation composition of lamps with additives Cs, K, Rb has a lower radiation intensity compared to standard high pressure sodium lamps (DNaT) in the region of 500-600 nm and significantly higher intensity in red (600-700 nm) and near infrared regions. The physicochemical properties of the sodium-cesium-mercury system have been studied. Melting points of ternary alloys, thermodynamic properties of melts of ternary system Na-Cs-Hg and double system of Na-Hg system are determined. The parameters of batch pressures of component vapors are calculated. The composition of the discharge tube amalgam is selected, in which the ratio of sodium and mercury concentrations is close to the corresponding ratio in a standard sodium lamp, and cesium additives vary in the range from 5 to 10 atm. %. The influence of cesium content in amalgams on light and color parameters of lamps is considered. Tomatoes were used in the experiment, which were additionally illuminated with lamps DNaT400, high intensity discharge tube filled light sources (20at.% Hg, 77at.% Na, 3at.% Cs20); (20at.% Hg, 75at.% Na, 5at. % Cs); (20 at. % Hg, 73 at. % Na, 7 at. % Cs); (20 at. % Hg, 70 at. % Na, 10 at. % Cs). Originality. In the use of high-pressure sodium lamps with a filling of the discharge tube in different weight ratios of Hg, Na, Cs. Practical value. When using high-intensity light sources with additives Cs having amalgam composition (20 at.% Hg, 75 at.% Na, 5 at.% Cs), growing tomato plants in the early stages of development is most effective. The total content of chlorophyll in tomatoes when irradiated with a high- pressure sodium lamp with cesium additives is 1.4 ÷ 2.5 times higher than when irradiated. DNaT400.

An integrated actuating and sensing system for light-addressable potentiometric sensor (LAPS) and light-actuated AC electroosmosis (LACE) operation.

To develop a lab on a chip (LOC) integrated with both sensor and actuator functions, a novel two-in-one system based on optical-driven manipulation and sensing in a microfluidics setup based on a hydrogenated amorphous silicon (a-Si:H) layer on an indium tin oxide/glass is first realized. A high-intensity discharge xenon lamp functioned as the light source, a chopper functioned as the modulated illumination for a certain frequency, and a self-designed optical path projected on the digital micromirror device controlled by the digital light processing module was established as the illumination input signal with the ability of dynamic movement of projected patterns. For light-addressable potentiometric sensor (LAPS) operation, alternating current (AC)-modulated illumination with a frequency of 800 Hz can be generated by the rotation speed of the chopper for photocurrent vs bias voltage characterization. The pH sensitivity, drift coefficient, and hysteresis width of the Si3N4 LAPS are 52.8 mV/pH, -3.2 mV/h, and 10.5 mV, respectively, which are comparable to the results from the conventional setup. With an identical two-in-one system, direct current illumination without chopper rotation and an AC bias voltage can be provided to an a-Si:H chip with a manipulation speed of 20 μm/s for magnetic beads with a diameter of 1 μm. The collection of magnetic beads by this light-actuated AC electroosmosis (LACE) operation at a frequency of 10 kHz can be easily realized. A fully customized design of an illumination path with less decay can be suggested to obtain a high efficiency of manipulation and a high signal-to-noise ratio of sensing. With this proposed setup, a potential LOC system based on LACE and LAPS is verified with the integration of a sensor and an actuator in a microfluidics setup for future point-of-care testing applications.

Formation of Intermediate SiO2 nano-Layer As Effective Passivation at Si/TiO2 Interface By Zone Heating Recrystallization Toward Perovskite/Silicon Tandem Solar Cell

A monolithic perovskite/c-Si tandem solar cell has attracted a lot of attention in the field of photovoltaic for its high theoretical energy conversion efficiency and cost-effectiveness. For this technology to reach its potential, optimization and compromised for both perovskite top cell and silicon bottom cell has to be investigated.In a single-junction perovskite solar cell, the hybrid organic-inorganic perovskite light-absorbing layer is sandwiched with electron and hole transporting layers (ETL and HTL). For optimal carrier extraction, the bandgap of the transporting layers has to match the perovskite material such that electron can be selectively transported to the ETL while only hole moves through HTL. In the majority of perovskite solar cells, titanium dioxide (TiO2) is used as ETL, for its high bandgap alignment, ease of fabrication, and low cost. For this reason, a tandem solar cell with c-Si/ETL(TiO2)/Perovskite/HTL structure has the potential to be highly efficient and low in cost [1].In a single-junction c-Si solar cell, surface passivation of silicon using large bandgap materials such as Al2O3, SiO2 or SiNx is widely known to reduce the velocity of carrier recombination and thus increase the carrier lifetime at silicon surface. This approach, however, is not applicable in tandem solar cells with c-Si/ETL/Perovskite/HTL structure, as the utilization of large bandgap materials in between c-Si and ETL causes bandgap misalignment and prevents interlayer exchange of carriers between perovskite and silicon cells. For this reason, a new approach that accommodates both interlayer exchange of carriers and passivate silicon surface effectively is required.In most of Si-Oxides (Al2O3, TiO2, ZnO, etc.) interface, the existence of SiOx layer is unavoidable and widely known due to high reactivity of silicon surface under oxidizing atmosphere [2]. Furthermore, while the improvement of perovskite solar cell efficiency by controlling spray pyrolysis of TiO2 and the thermal annealing procedure has been reported [3], prolonged exposure to heat during TiO2 fabrication might negatively affect the performance of silicon bottom cell, and thus requires further studies. Due to the high surface passivation effect of thermally grown SiO2 layer, we hypothesized that a proper crystallization of SiOx layer might be able to increase the lifetime of carrier at Si/TiO2 interface and mitigate the surface passivation problem in tandem solar cells with c-Si/ETL/Perovskite/HTL structure.Zone Heating Recrystallization (ZHR) is a process developed by our research group in which the surface of samples was selectively heated by the scanning of highly focus line lamp heater with elliptical mirror. Previously, we reported the utilization of ZHR to obtain smooth seed layers for thin-film silicon solar cell applications [4, 5] among other functionalities. The use of high-intensity lamp heater in ZHR process combines with high transparency of TiO2 layer makes ZHR a suitable process to selectively treat the Si/TiO2 interface and test our hypothesis on SiOx crystallization.With the introduction of ZHR, the minority carrier lifetime of Si/TiO2 interface was increased from less than 5 µs to more than 250 µs. Different scanning rates of lamp heater in ZHR process lead to different carrier lifetime, with higher scanning rates lead to higher carrier lifetime. To explain this phenomenon, cross-sectional TEM images of Si/TiO2 treated with different scanning rate was taken and analyzed. Here, we found that samples treated with higher scanning rates of ZHR have thinner SiOx layer and higher carrier lifetime. The relationship between SiOx thickness and carrier lifetime might be explained with the interface trap density of SiOx layer in which thinner layer shows lower interface trap density. This leads to lower carrier recombination velocity and therefore higher carrier lifetime at Si/TiO2 interface.References Mailoa J. P. et al., A 2-terminal perovskite/silicon multijunction solar cell enabled by a silicon tunnel junction. Appl. Phys. Lett. 106, 121105 (2015).Black L. E. et al., Explorative studies of novel silicon surface passivation materials: Considerations and lessons learned. Solar Energy Materials and Solar Cells 188, 182- 189 (2018).Nukunudompanich M., Ihara M. et al., Dominant effect of the grain size of the MAPbI3 perovskite controlled by the surface roughness of TiO2 on the performance of perovskite solar cell. CrysEngComm 22, 2718-2727 (2020).Ihara M. et al., Fabrication of silicon thin films with defects below detection limit of electron spin resonance for solar cells by high-speed zone-melting crystallization of amorphous silicon. Appl. Phys. Lett. 79, 3809 (2001).Lukianov A., Ihara M. et al., Formation of the seed layers for layer-transfer process silicon solar cells by zone-heating recrystallization of porous silicon structures. Appl. Phys. Lett. 108, 213904 (2016). Figure 1

Ablation-Dominated Arcs in CO2 Atmosphere—Part II: Molecule Emission and Absorption

Molecule radiation can be used as a tool to study colder regions in switching arc plasmas like arc fringes in contact to walls and ranges around current zero (CZ). This is demonstrated in the present study for the first time for the case of ablation-dominated high-current arcs as key elements of self-blast circuit breakers. The arc in a model circuit breaker (MCB) in CO2 with and an arc in a long nozzle under ambient conditions with peak currents between 5 and 10 kA were studied by emission and absorption spectroscopy in the visible spectral range. The nozzle material was polytetrafluoroethylene (PTFE) in both cases. Imaging spectroscopy was carried out either with high-speed cameras or with intensified CCD cameras. A pulsed high-intensity Xe lamp was applied as a background radiator for the broad-band absorption spectroscopy. Emission of Swan bands from carbon dimers was observed at the edge of nozzles only or across the whole nozzle radius with highest intensity in the arc center, depending on current and nozzle geometry. Furthermore, absorption of C2 Swan bands and CuF bands were found with the arc plasma serving as background radiator. After CZ, only CuF was detected in absorption experiments.

Space Environmental Chamber for Planetary Studies.

We describe a versatile simulation chamber that operates under representative space conditions (pressures from < 10−5 mbar to ambient and temperatures from 163 to 423 K), the SpaceQ chamber. This chamber allows to test instrumentation, procedures, and materials and evaluate their performance when exposed to outgassing, thermal vacuum, low temperatures, baking, dry heat microbial reduction (DHMR) sterilization protocols, and water. The SpaceQ is a cubical stainless-steel chamber of 27,000 cm3 with a door of aluminum. The chamber has a table which can be cooled using liquid nitrogen. The chamber walls can be heated (for outgassing, thermal vacuum, or dry heat applications) using an outer jacket. The chamber walls include two viewports and 12 utility ports (KF, CF, and Swagelok connectors). It has sensors for temperature, relative humidity, and pressure, a UV–VIS–NIR spectrometer, a UV irradiation lamp that operates within the chamber as well as a stainless-steel syringe for water vapor injection, and USB, DB-25 ports to read the data from the instruments while being tested inside. This facility has been specifically designed for investigating the effect of water on the Martian surface. The core novelties of this chamber are: (1) its ability to simulate the Martian near-surface water cycle by injecting water multiple times into the chamber through a syringe which allows to control and monitor precisely the initial relative humidity inside with a sensor that can operate from vacuum to Martian pressures and (2) the availability of a high-intensity UV lamp, operating from vacuum to Martian pressures, within the chamber, which can be used to test material curation, the role of the production of atmospheric radicals, and the degradation of certain products like polymers and organics. For illustration, here we present some applications of the SpaceQ chamber at simulated Martian conditions with and without atmospheric water to (i) calibrate the ground temperature sensor of the Engineering Qualification Model of HABIT (HabitAbility: Brines, Irradiation and Temperature) instrument, which is a part of ExoMars 2022 mission. These tests demonstrate that the overall accuracy of the temperature retrieval at a temperature between −50 and 10 °C is within 1.3 °C and (ii) investigate the curation of composite materials of Martian soil simulant and binders, with added water, under Martian surface conditions under dry and humid conditions. Our studies have demonstrated that the regolith, when mixed with super absorbent polymer (SAP), water, and binders exposed to Martian conditions, can form a solid block and retain more than 80% of the added water, which may be of interest to screen radiation while maintaining a low weight.

A simple Peltier cold trap aperture for protection of vacuum UV optics against hydrocarbons and reliable calibration of VUV spectrometers using D2 lamps

A simple Peltier cooled cold trap aperture is presented to minimize the flux of hydrocarbons on optics in vacuum UV systems. The system can be cooled down to −40 °C under vacuum. To test the effect of the cold trap, the aperture is placed in front of a high-intensity D2 lamp used for calibration in the range of 116 nm to 300 nm which is flanged to a VUV spectrometer. The influence of the aperture temperature is monitored by measuring the intensity loss rate of the Lyman-alpha emission line at 121.6 nm due to the formation of carbon contamination on the MgF2 window of the lamp depending on the Peltier temperature. The application of the aperture significantly reduced the intensity loss from approx. 20% h−1 to less than 2% h−1 and enables the reliable use of a D2 lamp for the relative intensity calibration of the spectrometer.

Failure rates among metal brackets cured with two high-intensity LED light-curing lamps: an in vivo study.

The objective of this split-mouth clinical trial was to compare bonding failure rates of metal brackets bonded with two different light-emitting diode (LED) light-curing lamps with different high-intensity power outputs. Forty patients were included for a total of 800 brackets that were randomly bonded (left and right sides in a 1:1 ratio) in maxillary and mandibular arches using two different LED devices. An LED of 3200 mW/cm2 and an LED of 5000 mW/cm2 were used in this split-mouth clinical trial. Bonding failures during the initial 6 months of orthodontic treatment were recorded as maxillary versus mandibular, anterior teeth versus posterior teeth, and left side versus right side. Five dropouts were recorded for discontinuing orthodontic treatment and 700 brackets were analysed in total. The bonding failure rates for 3200 and 5000 mW/cm2 LEDs were 6.0 and 7.4 per cent, respectively (P = 0.450), which were not statistically significantly different. There were no significant differences in bracket survival rates between the LEDs used (P = 0.866). The posterior teeth presented a higher index of bond failures (odds ratio, 3.14; 95% confidence interval, 1.68-5.87; P < 0.001). Direct comparison was only done between two high-intensity LED lights rather than against conventionally used halogen lights. Similar bonding failures were recorded using both LED devices (3200 and 5000 mW/cm2). Significantly more bonding failures occurred in premolar teeth than in anterior teeth.

Modeling of Discharge Lamp Characteristics by Using Floating Memristor Circuit Emulator with Tunable Threshold

A gas discharge lamp is a device, which operates as a light source by producing electrical discharge in ionized gaseous medium. Discharge lamps are commonly used in the market and according to their physical properties they can be mainly classified in three different categories: high pressure, low pressure and high-intensity lamps. Ionized gases have tendency to produce ongoing discharges and finally electrical arcs, which exhibit memristor characteristics proposed by Leon Chua. This paper introduces a novel fully floating memristor circuit emulator with tunable threshold characteristics which mimic discharge lamp characteristics. In order to investigate discharge lamp characteristics a test set-up is designed and commercially available discharge lamps are tested. The proposed memristor circuit displays distinctive characteristics in contrast to well-known smooth switching memristor characteristics in terms of hard switching capability. Proposed memristor has unique switching behavior and fully capable of modeling discharge lamps since it satisfies required zero-crossing, pinched hysteresis and frequency dependent characteristics of the discharge lamps. The comparisons of the current-voltage characteristics for both memristor and discharge lamps are supplied and investigated.

Thermal study of the atomic ratio effect on a cylindrical and an ellipsoidal shaped HgTlI discharge lamps

The purpose of this paper is to study the thermal behavior of a high-intensity HgTlI lamp in a cylindrical shape, compared to an ellipsoidal lamp during variations of the mercury to thallium atomic ratio. For this, we developed a chemical model under Local Thermodynamic Equilibrium conditions. Then, it was coupled with a three-dimensional code, time-dependent that solves the systems of equations for the mass, energy and momentum, as well as the equation of Laplace for the plasma using Comsol Multiphysics coupled with Matlab. Based on the variations of the mercury to thallium ratio, we analyzed the temperature fields, the heat conduction flow, the convective flow and the accumulation of mercury behind the electrodes for both of the shapes in different mercury to thallium ratios.

Variation in photon flux during extended photochemical aerosol experiments: Implications for atmospheric laboratory simulations

In order to simulate the interaction of sunlight with planetary atmospheres, including Pluto, Titan and the early Earth, many laboratory studies have used high-power broadband lamps with spectral features that extend into the vacuum-ultraviolet (VUV, <200 nm) to initiate photochemistry relevant to the atmosphere of interest. In many cases, experiments are run on the order of hundreds of hours with no accounting for how the photon flux within the system may be evolving with lamp age or a possible buildup of films over optical surfaces when working with high-yield photochemical systems. Given that the nature of photochemistry depends on the ratio of photons to reactants, variations in flux must be taken into account if the system is to be fully understood. In this study, standard N2O actinometry was used to measure the VUV flux of high-intensity deuterium lamps before, during, and after the photochemical synthesis of Titan analog aerosols made from methane or benzene precursors. It was found that VUV photon flux can be decreased by over 50% in under 10 h at higher number densities, with recorded flux losses of over 75% during extended (>60 h) photochemical experiments. While this is only one model system, it is apparent that changes in photon flux during simulations must be taken into account if adequate comparisons of the photochemical kinetics to their respective planetary environments are to be made.

Radiative properties of ceramic metal-halide high intensity discharge lamps containing additives in argon plasma

The lighting represents a consumption of about 19% of the world electricity production. We are thus searching new effective and environment-friendlier light sources. The ceramic metal-halide high intensity lamps (C-MHL) are one of the options for illuminating very high area. The new C-MHL lamps contain additives species that reduce mercury inside and lead to a richer spectrum in specific spectral intervals, a better colour temperature or colour rendering index. This work is particularly focused on the power radiated by these lamps, estimated using the net emission coefficient, and depending on several additives (calcium, sodium, tungsten, dysprosium, and thallium or strontium iodides). The results show the strong influence of the additives on the power radiated despite of their small quantity in the mixtures and the increase of visible radiation portion in presence of dysprosium.

Time-resolved spectra of solar simulators employing metal halide and xenon arc lamps

The time-resolved spectra of the irradiation emitted from solar simulators employing the two types of high-intensity discharge arc lamps that are commonly used in solar simulators, i.e. metal halide (here 6kW) and xenon arc (here 5kW) lamps, are reported. The lamp emission was recorded by a fast-response photodiode, which reveals that the amplitude of oscillating irradiation intensity from the metal halide lamp is approximately 60% of the peak intensity, while its oscillation frequency is twice of the frequency of the AC power supply, here 100Hz. The irradiation of the xenon arc lamp is powered by a modulated DC supply to oscillate at 300Hz, with an amplitude that is found to be only approximately 9% that of the peak intensity. An intensified CCD camera, which was coupled with a spectrometer operating in a range of 350–900nm, was synchronized with the lamp to provide phase-resolved spectra. The irradiation from the xenon arc lamp was found to be spectrally stable with time; while that from the metal halide lamp varies significantly throughout oscillation cycle, especially at the shorter-wavelengths of below 550nm. All spectra were calibrated to reveal that the time-averaged spectrum of the simulator with a metal halide lamp matches the solar spectrum significantly better than does that from a xenon arc lamp. The reflecting surface of polished ellipsoidal reflector was found to reduce the intensity of selected frequency bands by up to 10%, while that from both the polished ellipsoidal reflector and conical concentrator was found to reduce the intensity in selected frequency bands by up to 20%.

Application of high intensity UVC-LED for the removal of acetamiprid with the photo-Fenton process

Research into the use of light-emitting diodes (LEDs) for wastewater treatment has increased in recent years. LEDs are more efficient than other UV lamps because of their reduced heat dissipation and much longer life span. However, most of the UVC-LEDs that are currently available are of such low intensity that the large number of bulbs required for effective treatment of wastewater streams makes their application uneconomic. The development of higher intensity UVC-LEDs may therefore lead to more feasible technology options for wastewater treatment with UV-based advanced oxidation processes (AOPs). The aim of this work was to study the efficiency of high-intensity UVC-LED lamps (20W/m2) for the removal of micropollutants with the photo-Fenton process. The pesticide acetamiprid was used as model pollutant at a concentration of 100μg/L in synthetic secondary effluent due to its recalcitrant nature. Degradation using a low-pressure UVC-lamp (LPL) was also assessed for comparative purposes. The process was operated at pH 2.8 and at natural pH. The volumetric photon absorption (VRPA) was calculated for the results at acidic pH, where the catalyst was soluble, to investigate the influence of iron and hydrogen peroxide concentrations on acetamiprid degradation, based on their absorption for both systems. A model was proposed and results indicated that the contribution of both hydrogen peroxide and iron to the generation of radicals was the same in the LED system. At natural pH, the high intensity LED system was effective in the removal of acetamiprid, achieving degradation in 20min adding 1+1+1mgFe/L (sequential iron dosage) and 12mgH2O2/L.

Effect of Ambient Light on Near Infrared Spectroscopy

Background: Concerns have been raised about the ability of Near Infrared Spectroscopy (NIRS) to monitor skeletal tissue regional oxygen saturation (rSO2) in excessive light conditions, as are found under the overhead lights of the operating room. This study seeks to determine whether varying intensities of ambient light exert an influence on NIRS measurements of skeletal tissue rSO2. Methods: Thirty people were recruited from the staff of a local surgical center to participate in the study. Three separate NIRS devices (Covidien INVOS Cerebral Oximeter 510°C, Nonin EQUANOX Model 7600, and a CASMED MC-2030C Cerebral Oximeter) were used to obtain readings from the anterior compartment of the leg. Illuminance was recorded simultaneously with oximetry data in an operating room with (1) no lights on, (2) room lights, and (3) surgical lamps set to maximal intensity. Results: No differences were seen in rSO2 values under the different lighting conditions while using the Nonin device. There was a statistically significant difference between rSO2 for lights off versus room lights (-0.933, p=0.0045) as well as for lights off versus operating room (OR) lamps (level 5) (-0.50, p=0.0035) for the INVOS device, although the INVOS device was not always able to produce a reading in the presence of high-intensity OR light. While there was no difference found between lights off and room lights when using the CASMED device, it was unable to display a value in the presence of high-intensity OR lamp light. Conclusions: The results indicate that the presence of light has an effect on oximetry readings; however, the presence of such an effect is dependent upon the device being used. While other applications of the device, such as cerebral oximetry, may allow for drapes to cover the areas being monitored, monitoring for compartment syndrome of the leg would not be as forgiving. This application would be best served by a device capable of monitoring at all light levels.

Is the Photosuturing Agent, Rose Bengal, a Mutagen?

Rose Bengal (RB) is a potential photosuturing agent that may improve standard dermatologic surgical closure techniques. However, RB produces reactive oxygen species with photoactivation and its photomutagenic potential must be considered in clinical application. We investigated cytotoxicity, mutagenicity, and singlet oxygen (SO) production of RB on epithelial Chinese hamster ovary cell line. Cells were exposed to RB concentrations: 0.1%, 0.01%, 0.001%, 0.0001%, 0.00001%; irradiated for 400 s using a high-intensity visible wavelength lamp or maintained in the dark. Cell viability was assessed by XTT assay, mutagenicity by HPRT gene mutation assay, and SO production by Sensor Green reagent. RB > 0.001% was significantly cytotoxic. Viabilities were uninfluenced by ≤0.0001% RB controls, or 30-min incubation. 49% of irradiated cells died after 24-h in 0.0001% RB. At ≥0.001% RB, >90% of cells died. Irradiating 0.00001% - 0.001% RB increased SO; levels dropped significantly between 0.01% - 0.1%. Controls exhibited negligible SO production. HPRT suggested that RB was not mutagenic (0.0001%, 0.00001%); SO induction increased between 0.00001% - 0.001%, with reduced production at higher concentrations. Pilot studies suggested irradiated 0.0001% RB is mutagenic in vitro; current data suggest RB is not photomutagenic. The contribution of RB’s cytotoxicity on observed clinical improvement of scars and mutagenic potential remains unclear, necessitating further study.

Organotellurium-mediated living radical polymerization under photoirradiation by a low-intensity light-emitting diode.

A low-intensity (6 W) light-emitting diode (LED) effectively activated an organotellurium chain transfer agent and the dormant species, promoting well-controlled radical polymerization. The use of the LED provided many advantages over the previously reported high-intensity Hg lamp, including high energy efficiency during the polymerization, and easy availability of the low-cost light source. Structurally well-defined poly(methyl methacrylate), poly(methyl acrylate), and polystyrene, with narrow molecular weight distributions, were synthesized under LED irradiation with or without a neutral density filter.

Fusion Cladding Prevents Pipeline Wear and Corrosion

Abstract A new fusion cladding process that uses high-intensity arc lamps can produce pinhole free, smooth, uniform coatings as thick as 15 mm from various feedstock materials. This article briefly describes the process and the corrosion, wear, and high-temperature behavior of fusion claddings designed for oil and gas pipelines and related components.

A method of reducing background radiance for emissivity-compensated radiation thermometry of silicon wafers

We studied the spectral and directional emissivities of silicon wafers using an optical polarization technique. Based on simulation and experimental results, we developed two radiation thermometry methods for silicon wafers: one is based on the polarized emissivity-invariant condition and the other is based on the relationship between the ratio of the p- and s-polarized radiance and the polarized emissivity. These methods can be performed at temperatures above 600 °C and over a wide wavelength range (0.9-4.8 μm), irrespective of the dielectric film thickness and the substrate resistivity, which depends on the dopant concentration. The temperature measurements were estimated to have expanded uncertainties (k = 2) of less than 5 °C. With a view to practically applying these methods, we investigated a method to reduce the intense background radiance produced by high-intensity heating lamps. We found that the background radiance can be greatly reduced by using a radiometer that is sensitive to wavelengths of 4.5 or 4.8 μm and suitable geometrical arrangements of a quartz plate. This opens up the possibility of using the two proposed radiation thermometry methods in practical applications.

Electrodeless Mercury-Free Microwave-Driven Indium-Iodide-Based High-Intensity Discharges with High Color Rendering Index (June 2012)

In this paper, a method is shown to drive indium (I)-iodide-based discharges by microwaves in a compact setup. The microwave power is coupled into the discharge by a surfatron suitable for high-intensity discharges and small lamp diameters. A broad continuum in the spectral radiant flux of the lamps is shown at rather low pressures. High color rendering indexes were reached with color coordinates close to a thermal radiator. The dependence of the luminous flux on the lamps' filling condition is investigated. Buffering the discharge with elemental iodine decreases the discharges maintenance power.