The effect of halogen bulb and light-emitting diode light curing units on temperature increase and fibroblast viability

Background: This study aimed to compare the temperature increase produced by halogen bulb (HAL) and light-emitting diode (LED) light curing units (LCUs) by irradiating dentin discs (0.5 mm and 1 mm thickness), and to evaluate their cytotoxic effects on fibroblast culture in the presence of dentin discs due to the increasing demand on resin composite restorations and teeth bleaching for esthetic purposes. Methods: A total of 20 bovine incisors were used to obtain dentin discs and divided into four experimental groups (n=10): HAL0.5: irradiation with halogen-tungsten bulb Curing Light XL 3000 at an intensity of 470 mW/cm2 over a dentin disc of 0.5 mm; LED0.5: irradiation with LED Optilight Max (GNATUS- Ribeirão Preto, SP, Brazil) at an intensity of 1200 mW/cm2 over a dentin disc of 0.5 mm; HAL1: irradiation as in HAL0.5 but over a dentin disc of 1 mm; LED1: irradiation as in LED0.5 but over a dentin disc of 1 mm. The temperature increase was measured using a digital thermometer and the cytotoxicity was evaluated using an MTT assay with a mouse fibroblast cell line (L929). Parametric Data were analyzed by ANOVA and Tukey and non-parametric data were analyzed by Kruskal Wallis with Conover-Iman for non-parametric data (all with α=0.05). Results: A significant statistical difference was found between the groups HAL0.5 and HAL1 and both were different of LED0.5 and LED1 which presented higher temperature. All the experimental groups were different of the control group (without irradiation), and promoted reduction of cellular viability. Conclusions: HAL LCU promoted a lower temperature change in the dentin compared to LED, regardless of the dentin thickness (0.5-1 mm). Both HAL and LED LCUs decreased fibroblast viability; however, LED promoted more significant cytotoxic effects.

A 21 m Operation Range RFID Tag for “Pick to Light” Applications with a Photovoltaic Harvester

In this paper, a novel Radio-Frequency Identification (RFID) tag for “pick to light” applications is presented. The proposed tag architecture shows the implementation of a novel voltage limiter and a supply voltage (VDD) monitoring circuit to guarantee a correct operation between the tag and the reader for the “pick to light” application. The feasibility to power the tag with different photovoltaic cells is also analyzed, showing the influence of the illuminance level (lx), type of source light (fluorescent, LED or halogen) and type of photovoltaic cell (photodiode or solar cell) on the amount of harvested energy. Measurements show that the photodiodes present a power per unit package area for low illuminance levels (500 lx) of around 0.08 μW/mm2, which is slightly higher than the measured one for a solar cell of 0.06 μW/mm2. However, solar cells present a more compact design for the same absolute harvested power due to the large number of required photodiodes in parallel. Finally, an RFID tag prototype for “pick to light” applications is implemented, showing an operation range of 3.7 m in fully passive mode. This operation range can be significantly increased to 21 m when the tag is powered by a solar cell with an illuminance level as low as 100 lx and a halogen bulb as source light.

Anti-Glare Headlamp a Safe Option for Better Vision to the Rider

As per the Ministry of Road Transport and Highways report 2018, every day around 410 road fatalities in India, which is one of the highest road crash fatalities in the world. Evaluations show that an average of 1% of nighttime fatal crash lists glare as a major contributor factor. On the multilane highway, vehicle with high glared headlamp light disturbs the approaching motorist eyes due to which the vision of the motorist gets indistinct for a few seconds causing accidents on the road. In the present work, a novel concept of an anti-glare headlamp is proposed to avoid the temporary blindness of the motorist due to momentary high glares from approaching vehicles. The antiglare film reduces glare and halos around headlamp light at night and eliminates unattractive reflections on the eyes. A successful attempt is made to analyze the visibility of objects in a scene by inspecting contrast reduction caused by the illuminance contribution. Our visualization of scenes with the cover-up veiling illuminance gives a good indication of the visual problems that might occur, but the images are not exactly what people perceive when observing the scene in reality. In the present study, after number of samples, it has found that that the mixture of yellow and green color film combination on halogen bulb headlamp will give a good vision to the rider as well as glare-free effect to the approaching motorist. Visualizations with the proposed method can still improve the understanding of human vision so that visual aspects can be taken into account in design and quality assurance of head lamp.

Light stream emission validation of dipped and full beam headlight designed for HB3 halogen bulb after replacement by LED light source

The article describes analysis of a LED replacement for HB3 halogen bulb. It contains electrical and light parameters measurements of both light source types in terms of lighting the road at dusk and also photometric light shape comparison.

The Characterization of a Spectrum Splitter of TechSpec AOI 50.0mm Square Hot and Cold Mirrors Using a Halogen Light for a Photovoltaic-Thermoelectric Generator Hybrid

The characterization of a spectrum splitter of both hot and cold mirror, type TechSpec AOI 50.0, using a 50-Watt halogen bulb light has been done. Both the bulb spectrum, prior to and after spectrum splitting, are described in this study to see the degradation of radiation that occurs because partial energy is absorbed by the splitter. This characterization plays an important role in determining the best position of a photovoltaic (PV) and thermoelectric generator (TEG) in a PV-TEG system. The light spectrum was recorded using mini USB spectrometer hardware and Spectragryph version 1.2.8 software as optical spectroscopic software that displays light records coming with wavelength (nm) on the x-axis and light spectrum intensity in arbitrary units (a.u.) on the y-axis. The measurement results show that the light intensity in the visible light region (300–750) nm is more dominant than the intensity in infrared light (>750 nm), so that the PV placement is preferred over TEG. Furthermore, with a cold mirror, PV is more suitable if placed in a position to receive reflected light, while using a hot mirror is more suitable in the position transmitted light. For TEG, it is placed in a position opposite to PV. As a result, the maximum intensity of the PV light spectrum with cold mirrors is 46.52 a.u at a wavelength of 479.6 nm, while with hot mirrors it is 42.07 a.u with a 457.6 nm wavelength. It can be concluded that the value of the light intensity with a cold mirror is better than that with a hot mirror on the visible light (Vis) spectrum, and the current and voltage are equivalent to the results of the radiation energy area. It was proven that the maximum total output of a hybrid PV-TEG system with Cold Mirror is greater than that with Hot Mirror (100.53 > 68.77) × 10−3 µW. Based on the result of this study, it is recommended that further research can be conducted to increase radiation energy and output power in TEG.

Silicon Carbide UV Based Photovoltaic for Hostile Environments

The development of silicon carbide technologies has allowed for the development of sensors and electronics to measure the changes in a variety of hostile environments. A problem has been identified with reliable and efficient ways to power such sensors in these hostile environments. It is likely to be impractical to run power cables to these sensors and battery power has a finite lifetime. Recent research has demonstrated many energy scavenging techniques but to date none have been developed with a view of operation in hostile environments. To investigate the power density achievable from a SiC based energy scavenging device a SiC pin diode was exposed to both broad spectrum light form a tungsten halogen bulb and a 255 nm UV source. IV and CV measurements were used to determine the structural properties and photovoltaic response of the device, dark saturation current, induced photo current and the fill factor. We present the characteristics and maximum power density of these devices at temperatures between 300 K and 600 K. We demonstrate that the maximum power density achievable decreases with temperature. This is mostly due to the reduction in the built in potential from the pn junction, and the reduction of the generated photocurrent.

A simple cost-effective infra-red microscope for palynology

It has long been known that objects which are opaque in transmitted white light can become translucent in infra-red (IR) light. Its application to palynology was shown by Leclercq (1933) who used an IR filter to cut out the visible light from the specimen coupled with an IR-sensitive film to capture the image. Although the significance of this development was recognized (Walton, 1935), it was never generally used since oxidative methods such as Schulze’s solution are normally successful in clearing exines. The exceptions are opaque palynomorphs from thermally over-mature rocks. Such assemblages have been studied with IR microscopy using either IR-sensitive film on partially cleared material (e.g. Tiwari & Schaarschmidt, 1975) or electronic IR imaging systems (Cramer & Diez, 1972).The technical sophistication and performance of IR imaging microscopes has recently improved significantly following their routine application for the internal imaging of silicon chips. However, such microscopes are designed for use in reflected light and also rather costly. In addition their design makes them difficult to routinely switch from brightfield transmitted light to IR light without risk of damaging their sensitive IR tube. This note describes a simplified IR microscope for transmitted light which shows how excellent images of opaque spores in the near-IR can be produced using the simplest palynological microscope.This IR microscope is based around an Olympus BHSM-IR system. This is fitted with a 100W quartz halogen bulb which is essential for providing the required level of IR illumination. However, the only specific IR corrected optics this. . .