Detection, identification and mapping of cyanobacteria — Using remote sensing to measure the optical quality of turbid inland waters

The advantages of airborne scanning for the detection, identification and mapping of algal species, cyanobacteria and associated water parameters (such as turbidity) can be realized if current research outcomes are developed into operational methods based on images with high spectral resolution. Evidence for this has become available through data obtained recently in Australia from the Compact Airborne Spectrographic Imager. This paper shows how pigments associated with cyanobacteria are detectable, even in the very turbid waters typical of eastern Australia. It demonstrates how, if the waterbodies and their constituents can be characterized by a programme of field and laboratory measurement, current processing techniques and models allow the concentrations of different constituents (algae and particles) in the photic zone to be estimated and mapped. The challenge for operational remote sensing of optical water quality in Australia (and throughout the world) is seen to have two components. One is to provide an effective characterization of the target inland and adjacent coastal waters and the other is to streamline the data analysis to provide maps of water properties in the time and cost frameworks required for operational use.

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Growth and Characterization of Epsomite Single Crystals Doped with KCl from low Temperature Aqueous Solutions

Journal of Bangladesh Academy of Sciences ◽

10.3329/jbas.v33i1.2949 ◽

1970 ◽

Vol 33 (1) ◽

pp. 47-54 ◽

Cited By ~ 1

Author(s):

S Ferdous ◽

J Podder

Keyword(s):

Aqueous Solutions ◽

Single Crystals ◽

Optical Quality ◽

Dielectric Studies ◽

Slow Cooling ◽

Large Size ◽

Isothermal Evaporation ◽

Academy Of Sciences

Highly transparent and well faceted large size epsomite single crystals have been grown in pure form and doped with KCl from aqueous solutions by slow cooling and isothermal evaporation method. The optical quality of the epsomite improves on doping by KCl. Mass growth rates were found to increase with doping of lower concentrations of KCl and then decreases with the higher concentration of KCl. KCl doped epsomite crystal reveals that structures are slightly distorted due to adsorption of Cl- ion into the crystal lattice. DC conductivity along the growth axis for all of the grown crystals increases with temperature in the range of 25 to 70ºC and also increases with the KCl concentration. Dielectric constant is found to be almost independent of frequency up to range of 106Hz. The dielectric studies show the suitability of these grown crystals for optoelectronic applications. DOI: 10.3329/jbas.v33i1.2949 Journal of Bangladesh Academy of Sciences, Vol. 33, No. 1, 47-54, 2009

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Photoluminescence Characterization of SiGe/Si Quantum-Well Wire Structures

MRS Proceedings ◽

10.1557/proc-379-171 ◽

1995 ◽

Vol 379 ◽

Author(s):

S. Nilsson ◽

H. P. Zeindl ◽

A. Wolff ◽

K. Pressel

Keyword(s):

Quantum Well ◽

Room Temperature ◽

Molecular Beam ◽

Optical Quality ◽

Photoluminescence Spectra ◽

Single Quantum Well ◽

Quantum Well Wire ◽

Carbon Interstitial

ABSTRACTLow-temperature photoluminescence measurements were performed in order to probe the optical quality of SiGe/Si quantum-well wire structures fabricated by electron-beam lithography and subsequent reactive ion etching, having the patterned polymethylmethacrylate resist as an etch mask. In addition, one set of quantum-well wire structures was post-treated by means of annealing in a hydrogen environment. Our results show that even for the smallest wires of about 100nm in width, the wires exhibit phonon-resolved photoluminescence spectra, similar to that from the molecular beam eptitaxially grown SiGe single quantum well which was used as starting material for the patterning process. After the patterning process a new sharp peak appears in the photoluminescence spectra at 0.97eV in photon energy. Our investigation suggests that this feature is introduced by damage during the patterning process and most probably identical to the G-line, which previously was identified as originating from the dicarbon centre (substitutional carbon-interstitial carbon) in Si. This centre is known to be a very common endproduct of irradiating Si near room temperature which is the case at our patterning process.

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Characterization of optical quality of GaSe:Al crystals by exciton absorption peak parameters

Journal of Materials Science Materials in Electronics ◽

10.1007/s10854-014-1795-4 ◽

2014 ◽

Vol 25 (4) ◽

pp. 1757-1760 ◽

Cited By ~ 4

Author(s):

J. Guo ◽

J.-J. Xie ◽

L.-M. Zhang ◽

K. Kokh ◽

Yu. Andreev ◽

...

Keyword(s):

Optical Quality ◽

Absorption Peak ◽

Exciton Absorption

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Potentiostatic Deposition and Characterization of Cuprous Oxide Thin Films

ISRN Nanotechnology ◽

10.1155/2013/271545 ◽

2013 ◽

Vol 2013 ◽

pp. 1-4 ◽

Cited By ~ 5

Author(s):

A. El-Shaer ◽

A. R. Abdelwahed

Keyword(s):

Thin Films ◽

Cuprous Oxide ◽

Deposition Time ◽

Optical Quality ◽

Electrodeposition Technique ◽

Transparent Conducting ◽

Cupric Acetate ◽

Potentiostatic Deposition

Electrodeposition technique was employed to deposit cuprous oxide Cu2O thin films. In this work, Cu2O thin films have been grown on fluorine doped tin oxide (FTO) transparent conducting glass as a substrate by potentiostatic deposition of cupric acetate. The effect of deposition time on the morphologies, crystalline, and optical quality of Cu2O thin films was investigated.

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FABRICATION OF GaN HOMO-JUNCTION ON Si (111) SUBSTRATE FOR SENSOR APPLICATIONS

Journal of Molecular and Engineering Materials ◽

10.1142/s2251237312500062 ◽

2013 ◽

Vol 01 (01) ◽

pp. 1250006 ◽

Cited By ~ 1

Author(s):

M. Z. MOHD YUSOFF ◽

Z. HASSAN ◽

C. W. CHIN ◽

H. ABU HASSAN ◽

M. J. ABDULLAH ◽

...

Keyword(s):

Electrical Characterization ◽

High Energy ◽

Optical Quality ◽

X Ray Diffraction ◽

Raman Analysis ◽

Sensor Applications ◽

Current Voltage ◽

Good Optical Quality

In this paper, we investigated growth of GaN pn-homo junction layers on silicon (111) by plasma-assisted molecular beam epitaxy (PA-MBE) system and its application for photo-sensors. Silicon (Si) and magnesium (Mg) were used in this study as n- and p-dopants, respectively. Structural and optical analysis of the GaN homo-junction samples were performed by using reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), Raman spectroscopy and photoluminescence (PL) to analyze the crystalline quality of the samples. Surprisingly, the Raman analysis has revealed that there is no quenching of the A1 (LO) peak, with the presence of Si - and Mg -dopants in sample. The pn-junctions sample has good optical quality as measured by the PL system. Electrical characterization of the photo-sensors was carried out by using current–voltage (I–V) measurements.

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Microcomputed X-Ray Tomographic Imaging and Image Processing for Microstructural Characterization of Explosives

Materials ◽

10.3390/ma13204517 ◽

2020 ◽

Vol 13 (20) ◽

pp. 4517

Author(s):

John D. Yeager ◽

Lindsey A. Kuettner ◽

Amanda L. Duque ◽

Larry G. Hill ◽

Brian M. Patterson

Keyword(s):

Image Processing ◽

Automatic Segmentation ◽

Microstructural Characterization ◽

X Ray ◽

Typical Material ◽

Improve Measurement ◽

Segmentation Quality ◽

Processing Techniques

Microstructural characterization of composite high explosives (HEs) has become increasingly important over the last several decades in association with the development of high fidelity mesoscale modeling and an improved understanding of ignition and detonation processes. HE microstructure influences not only typical material properties (e.g., thermal, mechanical) but also reactive behavior (e.g., shock sensitivity, detonation wave shape). A detailed nondestructive 3D examination of the microstructure has generally been limited to custom-engineered samples or surrogates due to poor contrast between the composite constituents. Highly loaded (>90 wt%) HE composites such as plastic-bonded explosives (PBX) are especially difficult. Here, we present efforts to improve measurement quality by using single and dual-energy microcomputed X-ray tomography and state-of-the-art image processing techniques to study a broad set of HE materials. Some materials, such as PBX 9502, exhibit suitable contrast and resolution for an automatic segmentation of the HE from the polymer binder and the voids. Other composite HEs had varying levels of success in segmentation. Post-processing techniques that used commercially available algorithms to improve the segmentation quality of PBX 9501 as well as zero-density defects such as cracks and voids could be easily segmented for all samples. Aspects of the materials that lend themselves well to this type of measurement are discussed.

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Movpe Growth and Characterization of AlxGa1-xN Layers on Sapphire

MRS Proceedings ◽

10.1557/proc-468-23 ◽

1997 ◽

Vol 468 ◽

Cited By ~ 6

Author(s):

S. Clur ◽

O. Briot ◽

J. L. Rouviere ◽

A. Andenet ◽

Y-M. Le Vaillant ◽

...

Keyword(s):

Electron Microscopy ◽

Solid Phase ◽

Optical Quality ◽

Aluminum Concentration ◽

Al Content ◽

Transmission Electron ◽

Simple Kinetic Model ◽

Sudden Transition

ABSTRACTAlGaN is an important material for the realization of nitride heterostructures, involved in most device designs. We have studied the growth of this alloy using low pressure MOVPE (76 Torr), and using triethyl-gallium (TEGa), trimethyl-aluminum (TMA1) and ammonia (NH3) as precursors. First the solid -gas aluminum segregation was studied in order to calibrate the incorporation of Al in the solid phase. We found that aluminum is more readily incorporated than gallium in the solid, leading to an apparent Al segregation coefficient greater than unity. A simple kinetic model is used to fit the experimental data. Scanning electron microscopy has been used to investigate the morphology of the samples through the whole range of Al content (x = 0 to 1), and we observe a clear evolution of the surface features versus aluminum concentration: at low Al contents, small (below 1 pm) hexagonal holes are observed while at high Al, acicular features are observed, with a sudden transition between those morphologies around x = 0.5. Transmission electron microscopy was used to analyze the crystalline structure of these samples. Finally, the samples were studied by low temperature (2K) reflectivity and Raman spectroscopy. We report the evolution of the optical quality of samples (x < 0.4) versus Al content, as evaluated from the broadening of the observed excitonic transitions in the 2K reflectivity.

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