scholarly journals Microorganisms Photocatalytic Inactivation on Ag3PO4 Sub-microcrystals Under WLEDs Light Source

2021 ◽  
Author(s):  
João F Cruz-Filho ◽  
Tadeu M.S. Costa ◽  
Maciel S Lima ◽  
Luis F.G. Nolêto ◽  
Carla C. S. Bandeira ◽  
...  
Keyword(s):  
Inhibitory Effect ◽  
Luminous Flux ◽  
Relative Power ◽  
Oxygen Species ◽  
Light Emitting ◽  
Decimal Reduction Time ◽  
Photocatalytic Inactivation ◽  
Wall Permeability ◽  
Cell Wall Permeability ◽  
White Light Emitting Diodes

Abstract In this article, we report the silver orthophosphate (Ag3PO4) photocatalytic inactivation properties on strains Gram-positive Saprophyte B. subtilis, a diploid fungus Candida albicans and Gram-negative Pseudomonas aeruginosa, using as irradiation source white-light-emitting diodes (WLEDs) with luminous flux (Φ v) of 1.3 x 103 Lumens and relative power density of 15 mW m− 2. Microorganisms death curves and the kinetic constants (Kd) indicated that the inhibitory effect of the Ag3PO4 under WLEDs irradiation is well pronounced to C. albicans (6.6 x 10− 2 min− 1) in relation to P. augenosas (4.6 x 10− 2 min− 1) and B. subitilis (2.5 x 10− 2 min− 1). Decimal reduction time (Dt) were 34.4 min to C. albicans, 50.1 min P. augenosas and 92.1 min to B.subitilis The micrographs obtained by scanning electron microscopy with field emission gun (SEM-FEG) demonstrated that there was cell wall permeability and consequently total rupture in the C. albicans, suggesting the lipid peroxidation phenomenon and protein oxidation promoted by the presence of reactive oxygen species (ROS). Furthermore, it was observed the Ag3PO4 when irradiated by WLEDs demonstrates important sporicidal activity in related to B. subtilis, promoting the endospore wall rupture.

Datasheet-based methodology for CCT and luminous flux estimation in mixed-LED lighting sources

2020 ◽  
Author(s):  
Thais E. Bolzan ◽  
Bruno F. Almeida ◽  
Mateus O. K. Pereira ◽  
Renan R. Duarte ◽  
Vitor C. Bender ◽  
...  
Keyword(s):  
Maximum Error ◽  
Luminous Flux ◽  
Measured Data ◽  
Operating Conditions ◽  
Color Temperature ◽  
Experimental Setup ◽  
Light Emitting ◽  
Led Lighting ◽  
Flux Estimation ◽  
White Light Emitting Diodes

This work proposes a datasheet-based methodology to estimate the correlated color temperature (CCT) and the luminous flux of one or a combination of multiple white Light-Emitting Diodes (LEDs). This methodology is based on the interaction between the different domains (colorimetrical, optical, thermal and electrical) that control the LED's behavior. An experimental setup with LEDs of 4000K and 6500K CCT was built and tested under multiple operating conditions, in order to verify the accuracy of the proposed method. Results presented good correlation between estimated and measured data, with a maximum error of 1.05% for CCT and 3.13% for luminous flux.

The characteristic analysis of continuous light diodes

2021 ◽  
pp. 2150247
Author(s):  
I. T. Huseynov
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Light Flux ◽  
Continuous Light ◽  
Luminous Flux ◽  
Characteristic Analysis ◽  
Light Emitting ◽  
White Leds ◽  
Composite Solution ◽  
White Light Emitting Diodes

Photoluminescence (PL) spectra, light flux, color temperatures and color coordinates of white light emitting diodes that are based on CaGa2S4:Eu[Formula: see text]–CaS:Eu[Formula: see text] composite solution and industrial phosphor were analyzed. The study was carried out continuously for a 1000 h with two white LEDs which based on an exciting InGaN wavelength of 450 nm with a power of 10 W. Luminous flux and color temperatures were investigated during 200, 400, 600, 800 and 1000 h. All experiments were carried out for both CaGa2S4:Eu[Formula: see text]–CaS:Eu[Formula: see text] and industrial phosphor and comparatively analyzed. Consequently, the application perspectives of CaGa2S4:Eu[Formula: see text]–CaS:Eu[Formula: see text] composite solution in the white LEDs technologies are presented.

Optimization Spectrum of White Light Emitting Diodes Based on Correlated Color Temperature and Luminous Flux

2015 ◽  
Vol 44 (10) ◽  
pp. 1030001
Author(s):  
黄马连 HUANG Ma-lian ◽  
陈焕庭 CHEN Huan-ting ◽  
周小方 ZHOU Xiao-fang ◽  
蔡嘉毅 CAI Jia-yi ◽  
周锦荣 ZHOU Jin-rong ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Color Temperature ◽  
Light Emitting ◽  
White Light Emitting Diodes

scholarly journals Enhancing Luminous Efficacy of White Led Lamp Using Ca2MgSi2O7:Eu2+ Phosphor

2018 ◽  
Vol 2 (2) ◽  
pp. 103
Author(s):  
Doan Quoc Anh Nguyen ◽  
Thi Phuong Thao Nguyen ◽  
Postava Kamil
Keyword(s):  
Rapid Development ◽  
Essential Element ◽  
Luminous Flux ◽  
Luminous Efficacy ◽  
Light Emitting ◽  
White Leds ◽  
Creative Commons ◽  
Quality Scale ◽  
White Light Emitting Diodes

Along with the rapid development of science and technology in today's society, lighting technology, especially white light-emitting diodes (WLEDs), has become a critical and essential element in almost every field of our daily life. Therefore, the enhancement of luminous efficiency has become an important objective in the production of white LEDs to serve the needs of customers. This paper presents the influence of Ca2MgSi2O7:Eu2+ green luminescent phosphor on the light quality of WLEDs. In this work, the green-emitting Ca2MgSi2O7:Eu2+ phosphor is added into the in-cup phosphor configuration, which leads to the varying of the scattering property of this compounding. This is proved through the scattering coefficient from Mie-theory. Besides, the color quality scale which is called CQS index of WLEDs is also verified. The achieved results indicate that the luminous efficacy increases significantly if the Ca2MgSi2O7:Eu2+ concentration is varied. The smaller the Ca2MgSi2O7:Eu2+ size is used, the higher the luminous flux is obtained. However, the CQS can decrease if Ca2MgSi2O7:Eu2+ concentration is adjusted in another direction. Therefore, it is vital to select a suitable concentration and size of Ca2MgSi2O7:Eu2+ for enhancing the luminous efficacy of WLEDs, and the benet of this phosphor in creating white WLED packages is a potential solution for developing LED illumination technology.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

scholarly journals Preparation and Inverstigation of MEH-PPV Films Used for White Light Emitting Diodes

2011 ◽  
Vol 21 (2) ◽  
pp. 153
Author(s):  
Nguyen Nang Dinh ◽  
Do Ngoc Chung ◽  
Nguyen Phuong Hoai Nam ◽  
Pham Hong Duong
Keyword(s):  
White Light ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Emission Spectra ◽  
Luminous Flux ◽  
Heat Treatment Condition ◽  
Integrating Sphere ◽  
Light Emitting ◽  
Treatment Conditions ◽  
White Light Emitting Diodes

With the aim to prepare white Light Emitting Diode (WLED), the conjugate polymer films like (Poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) were investigated. Spectroscopic (absorption and emission) spectra of the MEH-PPV films showed that this polymer is suitable for casting onto the chips of the blue InGaN LED to make WLED. The luminous flux measured on the WLEDs in the integrating sphere proved that the white light emission can be obtained from the combination of inorganic LED and conjugate (MEH-PPV) polymers with an optimal thickness and a high quality. The aging process of MEH-PPV films was found to be strongly dependent post-treatment conditions. Reasonable heat treatment condition for the MEH-PPV polymers was suggested as in vacuum of 5×10-2 Pa at a temperature of 120°C in, for 2 hous.

scholarly journals Application of BaY2F8:Er3+,Yb3+ and Mg8Ge2O11F2:Mn4+ in improving the lighting quality of phosphor-in-glass based white light-emitting diodes with the dual-convex design

2021 ◽  
Vol 11 (4) ◽  
pp. 2934
Author(s):  
Huu Phuc Dang ◽  
Phung Ton That
Keyword(s):  
Red Light ◽  
Mie Scattering ◽  
Luminous Flux ◽  
Phosphor Material ◽  
Light Emitting ◽  
Quality Product ◽  
Accuracy Of Results ◽  
Light Material ◽  
White Light Emitting Diodes ◽  
Color Rendering

<span>Although the luminous of the remote phosphor structure tends to be better than that of the in-cup or conformal phosphor structures, the poor light quality prevents this lighting method from being widely used. It is recognized through experiments that the two-layer remote phosphorus structure should be used to improve color rendering index (CRI) and color quality ratio (CQS) for WLEDs. In the experiments, WLED structures containing green BaY2F8:Er3+,Yb3+ or red Mg8Ge2O11F2:Mn4+ phosphor on the yellow YAG:Ce3+ phosphor were performed at 8500 K.. After that, Mg8Ge2O11F2:Mn4+ and BaY2F8:Er3+,Yb3+ concentrations in each WLED structure is adjusted until chromatic performance reached the finest quality. As a result, Mg8Ge2O11F2:Mn4+is proved to bring great benefits to the increase of CRI and CQS. Specifically, the greater the concentration of Mg8Ge2O11F2:Mn4+, the better CRI and CQS because of the additional red-light material from this phosphor. The other phosphor material, green BaY2F8:Er3+,Yb3+ phosphor, is beneficial for the expansion of luminous flux. However, if the concentration of Mg8Ge2O11F2:Mn4+ or BaY2F8:Er3+,Yb3+ is over the limit, the decrease in lumen output and chromatic quality will occur. While doing the experiment, Mie-scattering theory and the Beer’s law are great tools to verify the accuracy of results. The results of this article can serve the purpose of improving WLEDs fabrication to produce higher quality product.</span>

scholarly journals The Sterol Carrier Hydroxypropyl-β-Cyclodextrin Enhances the Metabolism of Phytosterols by Mycobacterium neoaurum

2020 ◽  
Vol 86 (15) ◽  
Author(s):  
Liqiu Su ◽  
Shuangping Xu ◽  
Yanbing Shen ◽  
Menglei Xia ◽  
Xiaoxian Ren ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Low Cost ◽  
Inhibitory Effect ◽  
Sterol Metabolism ◽  
Content Type ◽  
Mycobacterium Neoaurum ◽  
Complex Functions ◽  
Wall Permeability ◽  
Cell Wall Permeability

ABSTRACT Androst-4-ene-3,17-dione (AD) and androst-1,4-diene-3,17-dione (ADD) are valuable steroid pharmaceutical intermediates obtained by soybean phytosterol biotransformation by Mycobacterium. Cyclodextrins (CDs) are generally believed to be carriers for phytosterol delivery and can improve the production of AD and ADD due to their effects on steroid solubilization and alteration in cell wall permeability for steroids. To better understand the mechanisms of CD promotion, we performed proteomic quantification of the effects of hydroxypropyl-β-CD (HP-β-CD) on phytosterol metabolism in Mycobacterium neoaurum TCCC 11978 C2. Perturbations are observed in steroid catabolism and glucose metabolism by adding HP-β-CD in a phytosterol bioconversion system. AD and ADD, as metabolic products of phytosterol, are toxic to cells, with inhibited cell growth and biocatalytic activity. Treatment of mycobacteria with HP-β-CD relieves the inhibitory effect of AD(D) on the electron transfer chain and cell growth. These results demonstrate the positive relationship between HP-β-CD and phytosterol metabolism and give insight into the complex functions of CDs as mediators of the regulation of sterol metabolism. IMPORTANCE Phytosterols from soybean are low-cost by-products of soybean oil production and, owing to their good bioavailability in mycobacteria, are preferred as the substrates for steroid drug production via biotransformation by Mycobacterium. However, the low level of production of steroid hormone drugs due to the low aqueous solubility (below 0.1 mmol/liter) of phytosterols limits the commercial use of sterol-transformed strains. To improve the bioconversion of steroids, cyclodextrins (CDs) are generally used as an effective carrier for the delivery of hydrophobic steroids to the bacterium. CDs improve the biotransformation of steroids due to their effects on steroid solubilization and alterations in cell wall permeability for steroids. However, studies have rarely reported the effects of CDs on cell metabolic pathways related to sterols. In this study, the effects of hydroxypropyl-β-CD (HP-β-CD) on the expression of enzymes related to steroid catabolic pathways in Mycobacterium neoaurum were systematically investigated. These findings will improve our understanding of the complex functions of CDs in the regulation of sterol metabolism and guide the application of CDs to sterol production.

scholarly journals Novel lighting properties of white LEDs with two-layered remote phosphor package using red-emitting α-SrO·3B2O3:Sm2+ phosphor

2017 ◽  
Vol 35 (3) ◽  
pp. 618-625
Author(s):  
Tran Hoang Quang Minh ◽  
Nguyen Huu Khanh Nhan ◽  
Nguyen Doan Quoc Anh ◽  
Hsiao-Yi Lee
Keyword(s):  
Lower Layer ◽  
Luminous Flux ◽  
Color Temperature ◽  
Phosphor Layer ◽  
Light Emitting ◽  
White Leds ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
White Light Emitting Diodes ◽  
Color Rendering

AbstractThis paper investigates a method for improving the lighting performance of white light-emitting diodes (WLEDs), packaged using two separating remote phosphor layers, yellow-emitting YAG:Ce phosphor layer and red-emitting α-SrO·3B2O3:Sm2+ phosphor layer. The thicknesses of these two layers are 800 μm and 200 μm, respectively. Both of them have been examined at average correlated color temperatures (CCT) of 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor has been varied from 2 % to 30 % in the upper layer, while in the lower layer the yellow phosphor concentration was kept at 15 %. It was found interesting that the lighting properties, such as color rendering index (CRI) and luminous flux, are enhanced significantly, while the color uniformity is maintained at a level relatively close to the level in one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer have been revised by combining Kubelka-Munk and Mie-Lorenz theories. Through the analysis, it is demonstrated that the packaging configuration of two-layered remote phosphor that contains red-emitting α-SrO·3B2O3:Sm2+ phosphor particles provides a practical solution to general WLEDs lighting.

scholarly journals Using CaCO3-doped package to improve correlated color temperature uniformity of white light-emitting diodes

2021 ◽  
Vol 11 (6) ◽  
pp. 4817
Author(s):  
My Hanh Nguyen Thi ◽  
Nguyen Thi Phuong Loan ◽  
Thuc Minh Bui ◽  
Hoang Van Ngoc
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Luminous Flux ◽  
Color Temperature ◽  
Resin Matrix ◽  
Light Emitting ◽  
Color Quality ◽  
Color Uniformity ◽  
Stability Enhancement ◽  
White Light Emitting Diodes

<span>The white light-emitting diode (WLED) has been the most advance lighting method currently, however, the fabrication process of this configuration still has drawbacks which negatively affect its color quality. This research was conducted to provide a method for WLED’s lighting output enhancement. Since CaCO<sub>3</sub> particles are excellent for thermal stability enhancement, especially when being combined with an adhesive substance, we decided to integrate CO<sub>3</sub> particles into resin matrix such as melamine formaldehyde (MF) and investigate their influences on the optical properties, including color uniformity and lumen output, of the WLED. The results showed that CaCO3 and MF resin are beneficial to the light scattering efficiency, which results in higher luminous flux and chromatic quality for WLED packages. In addition to that, the appropriate amounts of MF resin and CaCO<sub>3</sub> for reaching the best lumen efficiency and color quality are figured out at 1% and 10%, respectively. Moreover, another advantage of using MF resin and CaCO<sub>3</sub> for fabricating WLEDs is cost effectiveness. Hence, it has turned out that CaCO<sub>3</sub> and MF resins can be potential materials for next high-quality WLED generations.</span>

scholarly journals Employing SiO2 nano-particles in conformal and in-cup structures of 8500 K white LEDs

2021 ◽  
Vol 10 (3) ◽  
pp. 1709-1717
Author(s):  
My Hanh Nguyen Thi ◽  
Phung Ton That
Keyword(s):  
Blue Light ◽  
White Light ◽  
Sio2 Nanoparticles ◽  
Luminous Flux ◽  
Nano Particles ◽  
Color Temperature ◽  
Refractive Indices ◽  
Light Emitting ◽  
White Leds ◽  
White Light Emitting Diodes

SiO2 nano-particles have been examined in a distant phosphor structure for the elevated luminous quality and better consistency of white light-emitting diodes with angular-dependent associated color temperature (CCT). The luminous scattering ability could be increased by applying SiO2 nano-particles contain silicone to the outside of the phosphorus coating. In specific, the strength of blue light at wide angles is increased and differences in CCT can be minimized. In addition, owing to the sufficient refractive indices of silicone-containing SiO2 nanoparticles between the air and phosphorus layers, the luminous flux was improved. This new configuration decreases angular-dependent CCT deviations in the range of -700 to 700 from 1000 to 420 K. In comparison, at a 120 mA driving current, the rise of lumen flux increased by 2.25% relative to an usual distant phosphor structure without SiO2 nano-particles. As a result, in a distant phosphor structure, the SiO2 nano-particles could not only enhance the uniformity of illumination but also enhance the output of light.

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