scholarly journals Time-dependent growth of crystalline Au0-nanoparticles in cyanobacteria as self-reproducing bioreactors: 2.Anabaena cylindrica

2016 ◽  
Vol 7 ◽  
pp. 312-327 ◽  
Author(s):  
Liz M Rösken ◽  
Felix Cappel ◽  
Susanne Körsten ◽  
Christian B Fischer ◽  
Andreas Schönleber ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Production Method ◽  
Wide Distribution ◽  
Time Dependent ◽  
Anabaena Cylindrica ◽  
Vegetative Cells ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Dependent Growth ◽  
Average Size

Microbial biosynthesis of metal nanoparticles as needed in catalysis has shown its theoretical ability as an extremely environmentally friendly production method in the last few years, even though the separation of the nanoparticles is challenging. Biosynthesis, summing up biosorption and bioreduction of diluted metal ions to zero valent metals, is especially ecofriendly, when the bioreactor itself is harmless and needs no further harmful reagents. The cyanobacteriumAnabaena cylindrica(SAG 1403.2) is able to form crystalline Au0-nanoparticles from Au3+ions and does not release toxic anatoxin-a. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and laser-induced breakdown spectroscopy (LIBS) are applied to monitor the time-dependent development of gold nanoparticles for up to 40 hours. Some vegetative cells (VC) are filled with nanoparticles within minutes, while the extracellular polymeric substances (EPS) of vegetative cells and the heterocyst polysaccharide layer (HEP) are the regions, where the first nanoparticles are detected on most other cells. The uptake of gold starts immediately after incubation and within four hours the average size remains constant around 10 nm. Analyzing the TEM images with an image processing program reveals a wide distribution for the diameter of the nanoparticles at all times and in all regions of the cyanobacteria. Finally, the nanoparticle concentration in vegetative cells ofAnabaena cylindricais about 50% higher than in heterocysts (HC). These nanoparticles are found to be located along the thylakoid membranes.

Nanosecond laser-induced breakdown assisted by femtosecond laser pre-ionization in air: the effect on spatial resolution and continuous radiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20701
Author(s):  
Bo Li ◽  
Xiaofeng Li ◽  
Zhifeng Zhu ◽  
Qiang Gao
Keyword(s):  
Femtosecond Laser ◽  
Spatial Resolution ◽  
Laser Induced Breakdown Spectroscopy ◽  
Nanosecond Laser ◽  
Breakdown Threshold ◽  
Powerful Technique ◽  
Breakdown Spectroscopy ◽  
Continuous Radiation ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy (LIBS) is a powerful technique for quantitative diagnostics of gases. The spatial resolution of LIBS, however, is limited by the volume of plasma. Here femtosecond-nanosecond dual-pulsed LIBS was demonstrated. Using this method, the breakdown threshold was reduced by 80%, and decay of continuous radiation was shortened. In addition, the volume of the plasma was shrunk by 85% and hence, the spatial resolution of LIBS was significantly improved.

Characterization of Amethysts from Sukamara, Central Kalimantan, Using Laser-Induced Breakdown Spectroscopy (LIBS)

2020 ◽  
Vol 1 (2) ◽  
pp. 5-8
Author(s):  
Komang Gde Suastika, Heri Suyanto, Gunarjo, Sadiana, Darmaji
Keyword(s):  
Emission Intensity ◽  
Laser Energy ◽  
Emission Spectra ◽  
Atomic Emission ◽  
Laser Induced Breakdown Spectroscopy ◽  
Chemical Formula ◽  
Central Kalimantan ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Abstract - Laser-Induced Breakdown Spectroscopy (LIBS) is one method of atomic emission spectroscopy using laser ablation as an energy source. This method is used to characterize the type of amethysts that originally come from Sukamara, Central Kalimantan. The result of amethyst characterization can be used as a reference for claiming the natural wealth of the amethyst. The amethyst samples are directly taken from the amethyst mining field in the District Gem Amethyst and consist of four color variations: white, black, yellow, and purple. These samples were analyzed by LIBS, using laser energy of 120 mJ, delay time detection of 2 μs and accumulation of 3, with and without cleaning. The purpose of this study is to determine emission spectra characteristics, contained elements, and physical characteristics of each amethyst sample. The spectra show that the amethyst samples contain some elements such as Al, Ca, K, Fe, Gd, Ba, Si, Be, H, O, N, Cl and Pu with various emission intensities. The value of emission intensity corresponds to concentration of element in the sample. Hence, the characteristics of the amethysts are based on their concentration value. The element with the highest concentration in all samples is Si, which is related to the chemical formula of SiO2. The element with the lowest concentration in all samples is Ca that is found in black and yellow amethysts. The emission intensity of Fe element can distinguish between white, purple, and yellow amethyst. If Fe emission intensity is very low, it indicates yellow sample. Thus, we may conclude that LIBS is a method that can be used to characterize the amethyst samples.Key words: amethyst, impurity, laser-induced, breakdown spectroscopy, characteristic, gemstones

Research progress on portable laser-induced breakdown spectroscopy

2020 ◽  
Vol 13 (6) ◽  
pp. 1-18
Author(s):  
ZENG Qing-dong ◽  
◽  
YUAN Meng-tian ◽  
ZHU Zhi-heng ◽  
CHEN Guang-hui ◽  
...  
Keyword(s):  
Research Progress ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown
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