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Novel Mode-Locked Fiber Lasers with Broadband Saturable Absorbers
Published in Sam Zhang, Jyh-Ming Ting, Wan-Yu Wu, Functional Thin Films Technology, 2021
At present, SESAM is a mature SA and is widely used in mode-locked fiber lasers to achieve ultrashort pulse output at the femtosecond level [54–56]. However, with advances in science and technology, the requirements for SAs are increasing. In recent years, researchers have actively explored new SAs and applied them in mode-locked lasers. In 1997, quantum dot (QD) materials were used in lasers for the first time, and they successfully achieved pulse output[57]. QDs are considered to be quasi-zero-dimensional nanomaterials. Generally, semiconductor nanocrystals (such as CdSe) are incorporated into glass. Glass has a filtering effect, and the filtering effect of colored glass is used to produce saturated absorption characteristics. Since then, people have been studying nanomaterials as SAs.
Non-Invasive Techniques in Brain Activity Measurement Using Light or Static Magnetic Fields Passing Through the Brain
Published in Shoogo Ueno, Bioimaging, 2020
Light is scattered and goes in various directions in biological tissue. The nature of the medium with respect to light can be characterized by absorption and scattering. Water and glass are hardly scattered against ultraviolet rays, visible light, and infrared rays. They have the property of absorption only, which is small depending on the wavelength. A glass plate and water with a smooth surface are transparent without scattering or absorption in the wavelength range of visible light as shown in Figure 11.1(a). Colored glass appears colored to absorb light at wavelengths other than that color. However, polished glass, crushed glass fragments, and small glass balls where the surface is not smooth are not transparent. This is not because light is absorbed. In these cases, because of the roughness of the surface and internal heterogeneity, the light is randomly reflected at the surface, and the direction of the light changes inside the glass as shown in Figure 11.1(b). This phenomenon is scattering. Although the energy of light is attenuated by the absorption, there is no attenuation of energy by summing the energy of the scattered light.
Physical Drinking Water Parameters
Published in Frank R. Spellman, The Drinking Water Handbook, 2017
Pure water is colorless, but water in nature is often colored by foreign substances, including organic matter from soils, vegetation, minerals, and aquatic organisms that are often present in natural waters. Color can also be contributed by municipal and industrial wastes. Color in water is classified as either true color or apparent color. Color partly due to dissolved solids that remain after removal of suspended matter is known as true color; color contributed by suspended matter is the apparent color. In water treatment, true color is the most difficult to remove. Color in water, although not usually considered unsafe or unsanitary, does present a treatment problem because it exerts a chlorine demand, which reduces the effectiveness of chlorine as a disinfectant. Color is measured by comparing the water sample with standard color solutions or colored glass disks. One color unit (CU) is equivalent to the color produced by a 1-mg/L solution of platinum. In 1989, the USEPA issued a secondary MCL of 15 color units for color. At 10 to 15 color units, color may not be visually detectable; at 100 color units, water may have the appearance of tea.Note: In practice, the process of isolating and identifying specific chemicals that cause the color is not practical.
Heavy metals in municipal waste: the content and leaching ability by waste fraction
Published in Journal of Environmental Science and Health, Part A, 2019
Colored glass contains inert copper: the blue color of sodium-calcium glass and the green color of potassium-zinc glass is provided by cuprum (II) oxide. There still are many copper-containing pesticides: [7] Paris Green (copper acetoarsenite C4H6As6Cu4O16), Bordeaux mixture (CuSO4 · 5H2O + Ca(OH)2), copper trihydroxyl chloride Cu2(OH)3Cl. However, current application of these pesticides has decreased significantly. Copper compounds are used in silver-oxide and lithium batteries as lithium copper fluoride and lithium copper sulfide electrolytes [17]. Being a good conductor, copper is required in electrical cables and printed circuit boards providing the highest average concentration comparing to other metals in electronic waste (41 g kg−1) [17]. Also, about 14% of total copper in household waste is contained in fluorescent lamps [24]. Most aforementioned cuprum compounds are water-insoluble.
The length of axially segmented lifters in flighted rotary drums: influence on solid transport
Published in Drying Technology, 2022
Joscha Priessen, Fernando Barths, Malte Behrens, Heyko Juergen Schultz
Glass particles were used as bulk material for various reasons. On the one hand, glass is uniformly colored, unlike e.g., sand as a natural product. On the other hand, glass particles have a very narrow particle size distribution and a uniform spherical shape, and they also have a uniform density. This enables the investigation of solid transport processes without the influence of a broad particle size distribution. Any unknown or undesired density effects, e.g., segregation due to a gangue material, are avoided. Black colored glass particles were used as tracer material, so that the color is the only difference between both materials. For this purpose, a part of the bulk material was colored with water-soluble dye (conventional textile dye).
Application of glass with different impurities as an electron beam dosimeter
Published in Radiation Effects and Defects in Solids, 2022
H. Zareshahy, S. P. Shirmardi, M. Askarbioki, A. A. Sabouri Dodaran
Upon exposure to ionizing beams, the glass will experience excitation and atomic dislocation. EBs can result in permanent defects in the glass structure and alter its atomic lattice or the location of the impurity atoms (30). Some of these defects and alterations can lead to preferred absorption of light; resulting in colored glass; these defects are known as color centers (6, 31). These centers have different types and are related to optical absorption bands depending on the impurity type. ionization beam-induced color centers can contribute to various irradiation applications such as food industry, sterilization of medical tools, urban and industrial wastewater treatment and beam processing (32).