Stabilizers
Michael Bolgar, Jack Hubball, Joseph Groeger, Susan Meronek in Handbook for the Chemical Analysis of Plastic and Polymer Additives, 2016
It is important to note that while stabilizers can be divided into categories based on functionality, degradation of many polymers often occurs through sequential processes. For example, ultraviolet radiation will typically split bonds in many types of polymers. The broken chain ends are made reactive as a result and will typically react with ambient oxygen. Thus, ultraviolet energy indirectly causes oxidation. Protection of a polymer exposed to strong sunlight, for example, may be sufficiently protected with an ultraviolet inhibitor in the absence of an antioxidant; however, an antioxidant alone would not prevent polymer degradation. While oxidation may not occur, chain scission would progress, resulting in crazing and cracking of the polymer.
Introduction
Adrian Davies in Digital Ultraviolet and Infrared Photography, 2017
Ultraviolet (UV) and infrared (IR) photography both go back to the early years of the twentieth century. A characteristic utilised by many technical photographers is the way that UV and IR are absorbed or reflected by certain surfaces. Photography in the UV spectrum was possible relatively early in the history of photography, as the earliest photographic emulsions were naturally highly sensitive to both blue light and UV radiation. The advent of digital imaging in the 1990s meant that the often tedious darkroom work was no longer required, but instead, an understanding of how the sensors in digital cameras record light, and what is needed to enable them to record UV and IR. Today, most photographers wanting to shoot UV and IR images use cameras where the sensor has been modified by specialist camera repair companies to enable it to record wavelengths outside the visible spectrum.
Digital Camera Conversion and Other Equipment Considerations
Adrian Davies in Digital Ultraviolet and Infrared Photography, 2017
Digital cameras contain an imaging sensor, usually either a charge coupled device (CCD) or complementary metal oxide semiconductor (CMOS) type. Both CCD and CMOS imaging sensors are sensitive to wavelengths from around 200nm to 1200nm. According to Advanced Camera Services in the UK, who have converted hundreds of both CCD and CMOS cameras, there does not seem to be any noticeable difference between the two types of sensor when it comes to converting a camera for ultraviolet (UV) or infrared (IR). CCD and CMOS sensors are composed of a grid of light-sensitive cells known as picture elements, or pixels. A filter with dielectric coating, which reflects IR radiation and transmits visible light. The sensors on most modern digital cameras have a hot mirror filter over them to remove the IR and UV radiation and give the 'correct' colour for conventional photography.
UVGD 1.0: a gene-centric database bridging ultraviolet radiation and molecular biology effects in organisms
Published in International Journal of Radiation Biology, 2019
Hao Xu, Yan Wang, Lihong Diao, Xun Wang, Yi Zhang, Jiarun Zhu, Jinying Liu, Jingwen Yao, Zhongyang Liu, Yang Li, Fuchu He, Zhidong Wang, Yuan Liu, Dong Li
Objectives: Exposing to ultraviolet for a certain time will trigger some significant molecular biology effects in an organism. In the past few decades, varied ultraviolet-associated biological effects as well as their related genes, have been discovered under biologists’ efforts. However, information about ultraviolet-related genes is dispersed in thousands of scientific papers, and there is still no study emphasizing on the systematic collection of ultraviolet-related genes. Methods: We collected ultraviolet-related genes and built this gene-centric database UVGD based on literature mining and manual curation. Literature mining was based on the ultraviolet-related abstracts downloaded from PubMed, and we obtained sentences in which ultraviolet keywords and genes co-occur at single-sentence level by using bio-entity recognizer. After that, manual curation was implemented in order to identify whether the genes are related to ultraviolet or not. Results: We built the ultraviolet-related knowledge base UVGD 1.0 (URL: http://biokb.ncpsb.org/UVGD/), which contains 663 ultraviolet-related genes, together with 17 associated biological processes, 117 associated phenotypes, and 2628 MeSH terms. Conclusion: UVGD is helpful to understand the ultraviolet-related biological processes in organisms and we believe it would be useful for biologists to study the responding mechanisms to ultraviolet.
Effect of ultraviolet absorption reagent for determination of piperidinium ionic liquid cations by ion pair chromatography with indirect ultraviolet detection
Published in Journal of Liquid Chromatography & Related Technologies, 2017
Xin-xin Zhang, Hong Yu, Gang Wang
ABSTRACT Indirect ultraviolet detection method is a simple and effective method for the determination of ionic liquid cations without ultraviolet absorption group. This paper focused on the influence of different background ultraviolet absorption reagents on the determination of piperidinium ionic liquid cations by ion pair chromatography with indirect ultraviolet detection. Ultraviolet absorption reagents are divided into cationic (4-aminophenol hydrochloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, and N-ethylpyridinium tetrafluoroborate), anionic (potassium biphthalate and 5-sulfosalicylic acid), and amphiprotic (p-aminobenzoic acid). The results showed that piperidinium cations can be separated and detected by cationic and anionic ultraviolet absorption reagents. In general, the cationic ultraviolet absorption reagents have the best effect for separation and detection of the piperidinium cations by ion pair chromatography with indirect ultraviolet detection.
Detection of ultraviolet B radiation with internal smartphone sensors
Published in Instrumentation Science & Technology, 2017
Joanna Turner, Alfio V. Parisi, Damien P. Igoe, Abdurazaq Amar
ABSTRACT Smartphones have the potential to monitor ultraviolet radiation within the terrestrial solar spectrum. Additionally, the ability to accurately estimate personal ultraviolet exposure using a smartphone may one day allow an individual control of their ultraviolet exposure. Previous studies have demonstrated the detection of ultraviolet A from 320 to 400 nm with a smartphone. However, the measurement of ultraviolet B from 280 to 320 nm is desirable to monitor biological effects such as erythema. No previous reports have been reported for the detection of ultraviolet B detection with a smartphone camera. This study characterized the ultraviolet B response of smartphone cameras and shows that these devices detect this radiation without additional hardware. Three smartphones were tested in the ultraviolet B waveband for dark response, temperature response, irradiance response, and spectral response. The used protocols adhered to international standards where applicable. All characterized smartphones were sensitive to ultraviolet B radiation; however, each type provides a unique response.