Measurement of colour coordinates of LEDs used in the automotive exterior lighting

Article deals with dichromatic white light-emitting diode (LED’s) color coordinates used in automotive exterior lighting. This article also describes basic white automotive LED functionality and basic physical processes that create white light of these LEDs. It focuses on measuring color coordinates of white automotive LEDs with different temperature of LED and how the LED’s color depends on LED’s temperature. The article is comparing very important datasheet information of LED producers and values measured in the laboratory at university. The article contains statistical results of measurements and graphical representation of measured values and declared color bins which are very important for producers of headlamps for automotive companies

Purposeful Suppression and Reconstruction of White Light from LED for Improvement of Communication Properties

Visible Light Communication (VLC) technology uses white Light Emitting Diodes (LED) for providing illumination and communication at the same time. White LEDs have excellent illumination properties but their communication properties need improvement. This article proposes a way how to evade the communication limitations of white LEDs. A part of original white LED spectrum is suppressed by an optical filter. Then the suppressed part is replaced by another LED. The correct choice of suitable LED enables to reconstruct the original spectrum. This solution removes the limitations because the white LED emits continuously. Data are carried by the communication LED only. The evaluation of reconstruction of original white light is measurement of the colour coordinates x and y. Furthermore, the communication properties of this transmitter were tested and obtained results are shown in this paper. EVM parameter was measured

Polyphenolic profiles in lettuce (Lactuca sativa L.) after CaCl2 treatment and cold storage

Lettuce (Lactuca sativa L.) is a popular vegetable with the health-enhancing properties determined by high levels of antioxidant polyphenols as chlorogenic acids and other derivatives of caffeic acid or flavonoids. In this study, changes in the phenolic compound profiles in the lettuce leaves induced by application of CaCl2 before harvest and cold storage were studied. For the first time quantitative analysis of individual phenolic compounds on the basis of standards isolated from lettuce leaves was performed. Compounds were identified using HPLC, LC-MS, 1H and 13CNMR techniques. The dominant compounds were 2,3-dicaffeoyltartaric (2,3-diCTA), 5-O-caffeoylquinic (5-OCQA) and caffeoyltartaric (CTA) acids, with content of 5.7, 2.5 and 0.981 mg/g DM, respectively. The levels of individual phenolic compounds, total phenolics and antioxidant activity (DPPH assay) in plants treated by CaCl2 were determined throughout the storage period (7 and 14 days) at 4 °C. To ascertain the relationship between the content of individual compounds, total phenols, antioxidant activities and storage time, Pearson’s correlation analysis was used. The best correlation between the storage length and compound concentration was observed for 2,3-diCTA (R2 = 0.866) and caffeoylmalic acid (CMA) (R2 = 0.750). Application of CaCl2 (0.05M) on lettuce resulted in an increase in the levels of CTA, 2.3-diCTA and 5-OCQA about 120, 65 and 57%, respectively, compared to the control stored for 7 days in the same conditions and had a favourable effect on the antioxidant activity (R2 = 0.985). The present paper shows that CaCl2 may be used as an agent that influences the stability of health-promoting compounds of cold-stored lettuce