scholarly journals The Influence of LightPath Length on the Color of Flame-Fusion Synthetic Ruby

2021 ◽  
Author(s):  
Bin Yuan ◽  
Ying Guo ◽  
Ziyuan Liu
Keyword(s):  
Visible Light ◽  
Light Source ◽  
Path Length ◽  
Color Difference ◽  
Light Path ◽  
Light Spectrum ◽  
Strong Absorption Band ◽  
Vis Spectroscopy ◽  
Path Lengths ◽  
New Perspective

Abstract Colorimetric studies of different light path lengths from a new perspective of UV-Vis spectroscopy. The corrected ultraviolet-visible light spectrum was used to calculate the color of flame-fusion synthetic ruby, and the influence of light path length and standard light source on the color of flame-fusion synthetic ruby was studied. The results show that the L*, C*, h° under the A light source are higher than those under the D65 light source. In the ultraviolet-visible light spectrum, the strong absorption band of Cr3+ at 545nm is the main cause of the color of the ruby. As the length of the light path increases, the absorption peak area at 545nm also increases, the lightness L* decreases, and the hue angle h° increases. The chroma C* first increases as the length of the light path increases, and then begins to decrease under the influence of the continuous decrease in lightness. The color difference ΔE*ab reaches the maximum when the light path length is around 10mm, and the standard light source has the greatest influence on the color difference ΔE*ab. As the length of the light path continues to increase, the influence of the standard light source on the color difference\(\)ΔE*ab decreases.

scholarly journals Synthesis Method Effect of CoFe2O4on Its Photocatalytic Properties for H2Production from Water and Visible Light

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Yudith Ortega López ◽  
Hugo Medina Vázquez ◽  
Jesús Salinas Gutiérrez ◽  
Vanessa Guzmán Velderrain ◽  
Alejandro López Ortiz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Ball Milling ◽  
Synthesis Method ◽  
Milling Process ◽  
Bet Surface Area ◽  
Light Spectrum ◽  
Vis Spectroscopy ◽  
Adsorption Desorption

Currently, the need for more efficient materials that work in the visible light spectrum for hydrogen production has been increasing. Under this criterion, ferrites are ideal because their energetic properties are favorable to photocatalysis as they have a low band gap (1.5 to 3 ev). In this particular research, ferrite is presented as a hydrogen producer. Cobalt ferrites were synthesized by chemical coprecipitation (CP) and ball milling (BM) for comparison of their performance. The characterization of the materials was carried out with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET surface area, UV-VIS spectroscopy, and water adsorption/desorption tests. Evaluation of the photocatalytic activity under visible light was followed by gas chromatography. The results showed that cobalt ferrite by ball milling had a higher photocatalytic activity; this is attributed to the vacancies generated during the milling process at which the sample was exposed.

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

Green synthesized Ag-TiO2 for degradation of organic dye through visible light driven photo-reactor and its kinetics

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Titikshya Mohapatra ◽  
Sakshi Manekar ◽  
Vijyendra Kumar Sahu ◽  
Ashwini Kumar Soni ◽  
Sudip Banerjee ◽  
...  
Keyword(s):  
Visible Light ◽  
Mangifera Indica ◽  
Band Gap Energy ◽  
Photo Degradation ◽  
X Ray ◽  
Green Approach ◽  
Vis Spectroscopy ◽  
Rate Of Reaction ◽  
Visible Light Driven ◽  
Modification Of Titanium

Abstract This study reports a green approach for the modification of titanium dioxide (TiO2) nanoparticles with immobilization of silver nanoparticles. One of the natural sources i.e., Mangifera indica leaf extract was utilized as reducing and capping agent for the fabrication of Ag-TiO2 nanocatalyst. Further, the surface morphology and band-gap energy of prepared Ag-TiO2 were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and UV–Vis spectroscopy. Also, it was characterized by X-ray Powder Diffraction (XRD) which provides the information regarding the crystallinity of the Ag-TiO2. Subsequently, photo activity of Ag-TiO2 was investigated for the degradation of methylene blue (MB) dye wastewater through visible light driven photoreactor. The Ag-TiO2 provided highest (68%) of photo-degradation efficiency within 110 min for 7.81 × 10−5 mol/L initial MB concentration at pH 8 by using 0.19 g/L photocatalyst. Further, addition of 10 mM H2O2 boost up the MB photodegradation to 74%. The kinetic study confirmed the MB degradation followed first order rate of reaction.

Uniform-intensity, visible light source for in situ imaging

2009 ◽  
Vol 14 (2) ◽  
pp. 024024 ◽  
Author(s):  
Eyal Bar-Kochba ◽  
Saagar Govil ◽  
Jon P. Longtin ◽  
Andrew Gouldstone ◽  
Mary D. Frame
Keyword(s):  
Visible Light ◽  
Light Source ◽  
In Situ Imaging

scholarly journals Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Chun-Hung Huang ◽  
Yu-Ming Lin ◽  
I-Kai Wang ◽  
Chun-Mei Lu
Keyword(s):  
Visible Light ◽  
Carbon Number ◽  
Red Light ◽  
Matrix Material ◽  
Carbon Sources ◽  
Impregnation Method ◽  
Light Spectrum ◽  
Precursor Molecule ◽  
Visible Light Active ◽  
Carbonate Species

A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities ofNOxphotodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the totalNOxremoval under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O), which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

Bioinspired micro/nanomotor with visible light energy–dependent forward, reverse, reciprocating, and spinning schooling motion

2021 ◽  
Vol 118 (42) ◽  
pp. e2104481118
Author(s):  
Jintao Tong ◽  
Dalei Wang ◽  
Ye Liu ◽  
Xin Lou ◽  
Jiwei Jiang ◽  
...  
Keyword(s):  
Visible Light ◽  
Light Source ◽  
Carbon Nitride ◽  
Free Carbon ◽  
Light Energy ◽  
Negative Phototaxis ◽  
Schooling Behavior ◽  
Low Illumination ◽  
Energy Dependent ◽  
High Irradiation

In nature, microorganisms could sense the intensity of the incident visible light and exhibit bidirectional (positive or negative) phototaxis. However, it is still challenging to achieve the similar biomimetic phototaxis for the artificial micro/nanomotor (MNM) counterparts with the size from a few nanometers to a few micrometers. In this work, we report a fuel-free carbon nitride (C3N4)/polypyrrole nanoparticle (PPyNP)-based smart MNM operating in water, whose behavior resembles that of the phototactic microorganism. The MNM moves toward the visible light source under low illumination and away from it under high irradiation, which relies on the competitive interplay between the light-induced self-diffusiophoresis and self-thermophoresis mechanisms concurrently integrated into the MNM. Interestingly, the competition between these two mechanisms leads to a collective bidirectional phototaxis of an ensemble of MNMs under uniform illuminations and a spinning schooling behavior under a nonuniform light, both of which can be finely controllable by visible light energy. Our results provide important insights into the design of the artificial counterpart of the phototactic microorganism with sophisticated motion behaviors for diverse applications.

An Algorithm for a Near Optimal NC Path Generation in Staircase (Lase) Traversal of Convex Polygonal Surfaces

1999 ◽  
Vol 122 (1) ◽  
pp. 182-190 ◽  
Author(s):  
S. V. Kamarthi ◽  
S. T. S. Bukkapatnam ◽  
S. Hsieh
Keyword(s):  
Rapid Prototyping ◽  
Path Length ◽  
Tool Path ◽  
Path Generation ◽  
Convex Polygons ◽  
Sweep Angle ◽  
Pocket Milling ◽  
Different Shapes ◽  
Path Lengths ◽  
Better Than

This paper presents an analytical model of the tool path for staircase traversal of convex polygonal surfaces, and an algorithm—referred to as OPTPATH—developed based on the model to find the sweep angle that gives a near optimal tool path length. The OPTPATH algorithm can be used for staircase traversal with or without (i) overlaps between successive sweep passes, and (ii) rapid traversal along edge passes. This flexibility of OPTPATH renders it applicable not only to conventional operations such as face and pocket milling, but also to other processes such as robotic deburring, rapid prototyping, and robotic spray painting. The effective tool path lengths provided by OPTPATH are compared with those given by the following two algorithms: (i) a common industrial heuristic—referred to as the IH algorithm—and (ii) an algorithm proposed by Prabhu et al. (Prabhu, P. V., Gramopadhye, A. K., and Wang, H. P., 1990, Int. J. Prod. Res., 28, No. 1, pp. 101–130) referred to as PGW algorithm. This comparison is conducted using 100 randomly generated convex polygons of different shapes and a set of seven different tool diameters. It is found that OPTPATH performs better than both the IH as well as PGW algorithms. The superiority of OPTPATH over the two algorithms becomes more pronounced for large tool diameters. [S1087-1357(00)71501-2]

scholarly journals Differences between Tempos of Step Error and Postural Sway in the Stipulated Tempo Step Test for Children and Their Relationships

2021 ◽  
Vol 11 (6) ◽  
pp. 31
Author(s):  
Hiroki Aoki ◽  
Shin-ichi Demura ◽  
Kenji Takahashi ◽  
Hiroshi Hirai
Keyword(s):  
Repeated Measures ◽  
Path Length ◽  
Postural Sway ◽  
Dynamic Balance ◽  
Step Test ◽  
Total Path Length ◽  
Fast Tempo ◽  
Balance Ability ◽  
Path Lengths ◽  
Slow Tempo

Recently, to evaluate dynamic balance ability, a stipulated tempo step test has been developed, and a step error between tempo and contact time of feet has been used as an evaluation variable. The step error, postural sway, and their relationships may differ between the slow tempo (40 bpm) and fast tempo (120 bpm). This study aimed to examine the aforementioned problem with 62 participant children (30 boys and 32 girls). The step error and postural sway variables (X-axis path length, Y-axis path length, total path length, peripheral area, and rectangular area) during stepping while matching both tempos were measured. Means of one minute and three intervals (0–20 sec, 20–40 sec, and 40–60 sec) for each variable were calculated in both tempos. The results of the paired t-test showed that means of all variables were larger in the 40 bpm tempo than in the 120 bpm tempo. In the multiple comparison tests after the results of the two-way repeated measures ANOVA, the means of three intervals in all variables were larger in the 40 bpm tempo than in the 120 bpm tempo; the means of the sway variables, excluding that of the X-axis path length, in the 40 bpm tempo were larger in the 0–20 sec interval than in the 20–40 sec interval or the 40–60 sec interval. Correlations between step errors and those between the step error and sway variables of both tempos were insignificant or under moderation. The correlations between the step error and sway variables in both tempos were insignificant or significant but low, and those among sway variables were high, except between the X- and Y-axis path lengths. The relationship between both axis path lengths differed according to the tempo. In conclusion, in the case of the stipulated tempo step test targeting children, the slow tempo has a greater step error and postural sway than the fast tempo, and the sway in the early step stage is greater in the slow tempo. The relationships between step errors and between the step error and sway variables of both tempos are low; hence, the ability related to the test may differ in both tempos. The relationships among sway variables in both tempos are high, except between the X- and Y-axis path lengths.

scholarly journals A Modular, Self-Assembling Metallaphotocatalyst for Cross Couplings Using the Full Visible-Light Spectrum

2020 ◽  
Author(s):  
Susanne Reischauer ◽  
Volker Strauss ◽  
Bartholomäus Pieber
Keyword(s):  
Titanium Dioxide ◽  
Visible Light ◽  
Excited States ◽  
Catalyst System ◽  
Chemical Energy ◽  
Modular Approach ◽  
Nickel Catalysis ◽  
Light Spectrum ◽  
Dye Sensitized ◽  
Self Assembling

The combination of nickel- and photocatalysis has unlocked a variety of cross couplings. These protocols rely on a few photocatalysts that can only convert a small portion of visible light (<500 nm) into chemical energy. Many dyes that absorb a much broader spectrum of light are not applicable due to their short-lived excited states. Here we describe a self-assembling catalyst system that overcomes this limitation. The modular approach combines nickel catalysis with dye-sensitized titanium dioxide and can be used to catalyze various bond formations. <br>

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