- Egypt
In this paper, we were able to record luminescence spectra of olive, sunflower, corn, gourd and laurel oils, chlorophyll and carotene by using an argon laser (488–514 nm) and second harmonic Nd‐YAG laser (532 nm) along with a... more
In this paper, we were able to record luminescence spectra of olive, sunflower, corn, gourd and laurel oils, chlorophyll and carotene by using an argon laser (488–514 nm) and second harmonic Nd‐YAG laser (532 nm) along with a monochromator whose spectral range is 400–900 nm. Only when the luminescence light is vertical to laser light, two new peaks 540 nm and 673 nm have been detected with the latter one is more intense. In discussing our results, we succeeded in determining which materials in olive oil are responsible for producing the luminescence spectral peak; 673 nm. The experimental data has shown that the chlorophyll is the main part of the olive components which gives the olive oil luminescence spectral peak; 673 nm. The other luminescence spectral peak; 540 nm was common to all different kinds of oil in general.
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Rapid and successful clinical diagnosis and bacterial infection treatment depend on accurate identification and differentiation between different pathogenic bacterial species. A lot of efforts have been made to utilize modern techniques... more
Rapid and successful clinical diagnosis and bacterial infection treatment depend on accurate identification and differentiation between different pathogenic bacterial species. A lot of efforts have been made to utilize modern techniques which avoid the laborious work and time-consuming of conventional methods to fulfill this task. Among such techniques, laser-induced breakdown spectroscopy (LIBS) can tell much about bacterial identity and functionality. In the present study, a sensitivity-improved version of LIBS, i.e. nano-enhanced LIBS (NELIBS), has been used to discriminate between two different bacteria (Pseudomonas aeruginosa and Proteus mirabilis) belonging to different taxonomic orders. Biogenic silver nanoparticles (AgNPs) are sprinkled onto the samples’ surface to have better discrimination capability of the technique. The obtained spectroscopic results of the NELIBS approach revealed superior differentiation between the two bacterial species compared to the results of the ...
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Optical clearing is a relatively new approach to enhancing the optical transparency of biological tissues by reducing their scattering properties. The optical clearing effect is achievable via various chemical, physical, and photo-thermal... more
Optical clearing is a relatively new approach to enhancing the optical transparency of biological tissues by reducing their scattering properties. The optical clearing effect is achievable via various chemical, physical, and photo-thermal techniques. The present work studied optical parameters of bovine skeletal muscles under different clearing protocols: immersion optical clearing in 99% glycerol and photo-thermal optical clearing via exposure to IR laser irradiation. Moreover, the two techniques were combined with different immersion time intervals after multiple exposure periods to get optimum results. The muscle samples’ diffuse reflectance and total transmittance were measured using a single integrating sphere and introduced to the Kubleka–Munk mathematical model to determine the absorption and reduced scattering coefficients. Results revealed a 6% scattering reduction after irradiating the sample for 10 min and immersing it in glycerol for 18 min and 8% after 20 min of laser i...
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Laser Induced Breakdown Spectroscopy (LIBS) is a well known spectrochemical elemental analysis technique. In our investigations of the LIBS spectra it has been found that there is a remarkable correlation between the ionic to atomic... more
Laser Induced Breakdown Spectroscopy (LIBS) is a well known spectrochemical elemental analysis technique. In our investigations of the LIBS spectra it has been found that there is a remarkable correlation between the ionic to atomic spectral lines emission ratio and the surface hardness of solid targets. This phenomenon is related to the repulsive force of the laser induced shockwaves. The present study revealed a confirmation of the above mentioned correlation and the interpretation of the phenomenon in view of the laser induced shockwaves velocity has been also proved experimentally. The relation between the target surface hardness and the ionic to atomic spectral lines intensity ratio of Zr in specially prepared steel alloys treated thermally to have different surface hardness, has been estimated via LIBS. The obtained LIBS spectra have been used to obtain Iionic/Iatomic for certain spectral lines of minor elements in the investigated alloys. The obtained linear relation between the steel samples surface hardness (measured mechanically) and the spectral lines ratio confirm the same effect. The above investigations open the door for LIBS to be exploited not only as a spectrochemical analytical technique but also as an easy way to measure the surface hardness of solid targets.
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Laser-induced breakdown spectroscopy (LIBS), known also as laser-induced plasma spectroscopy (LIPS), is a well-known spectrochemical elemental analysis technique. The field of LIBS has been rapidly matured as a consequence of growing... more
Laser-induced breakdown spectroscopy (LIBS), known also as laser-induced plasma spectroscopy (LIPS), is a well-known spectrochemical elemental analysis technique. The field of LIBS has been rapidly matured as a consequence of growing interest in real-time analysis across a broad spectrum of applied sciences and recent development of commercial LIBS analytical systems. In this brief review, we introduce the contributions of the research groups in the African continent in the field of the fundamentals and applications of LIBS. As it will be shown, the fast development of LIBS in Africa during the last decade was mainly due to the broad environmental, industrial, archaeological, and biomedical applications of this technique.
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J. Anal. At. Spectrom., 2011, Advance Article DOI:10.1039/C1JA10057B (Paper) PDF Version. Influence of biological degradation and environmental effects on the interpretation of archeological bone samples with laser-induced breakdown... more
J. Anal. At. Spectrom., 2011, Advance Article DOI:10.1039/C1JA10057B (Paper) PDF Version. Influence of biological degradation and environmental effects on the interpretation of archeological bone samples with laser-induced breakdown spectroscopy. ...
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The purpose of this paper is to provide the reader with comparative information about two new commercial echelle spectrometers equipped with intensified CCD (ICCD) detectors for laser-induced breakdown spectroscopy analysis. We carried... more
The purpose of this paper is to provide the reader with comparative information about two new commercial echelle spectrometers equipped with intensified CCD (ICCD) detectors for laser-induced breakdown spectroscopy analysis. We carried out a performance comparison between two commercial ICCD/echelle spectrometers [ESA 3000 (LLA Instruments GmbH, Berlin-Adlershof, Germany) and a Mechelle 7500 (Multichannel Instruments, Stockholm, Sweden)] for the determination of the concentrations of Be, Mg, Si, Mn, Fe, and Cu in the same Al alloy samples adopting the same experimental conditions. The results show that both systems, despite their differences in terms of resolution, have similar performance in terms of sensitivity and precision of measurements for these elements in an Al alloy matrix at least for the range of wavelength 280-400 nm studied in this work.
Research Interests: Mechanical Engineering, Physics, Materials Science, Optics, Plasma Physics, and 15 moreLaser Spectroscopy, Signal Processing, Laser, Spectroscopy, Sensitivity Analysis, Medicine, Applied Optics, Optical physics, Laser Matter Interactions, Laser Induced Breakdown Spectroscopy, Image Sensor, Performance Comparison, Detector, Electrical And Electronic Engineering, and Spectrometer
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ABSTRACT Laser-induced Plasma spectroscopy (LIPS) is a useful method for determining the elemental composition of various materials but for long time it have been mainly restricted to qualitative and quantitative analysis of samples... more
ABSTRACT Laser-induced Plasma spectroscopy (LIPS) is a useful method for determining the elemental composition of various materials but for long time it have been mainly restricted to qualitative and quantitative analysis of samples material. Recently LIPS is applied in addition to depth-profile analysis. In this paper we were trying to investigate the differences in the depth profile, obtained adopting femtosecond LIPS, that may occur on changing the spectral lines chosen for the analysis. The used femtosecond laser has pulse duration of 130 fs, wave length of 795 nm and pulse energy 200 muJ. It was found that the differences observed were not significant as long as the spectral lines chosen are fulfilling the LIPS spectral lines conditions.
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Monitoring of the spectrochemical and optical properties of biomaterials has been widely utilized in many biomedical applications for both diagnosis and therapy.
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Fish is an essential source of many nutrients necessary for human health. However, the deliberate mislabeling of similar fish fillet types is common in markets to make use of the relatively high price difference. This is a type of... more
Fish is an essential source of many nutrients necessary for human health. However, the deliberate mislabeling of similar fish fillet types is common in markets to make use of the relatively high price difference. This is a type of explicit food adulteration. In the present work, spectrochemical analysis and chemometric methods are adopted to disclose this type of fish species cheating. Laser-induced breakdown spectroscopy (LIBS) was utilized to differentiate between the fillets of the low-priced tilapia and the expensive Nile perch. Furthermore, the acquired spectroscopic data were analyzed statistically using principal component analysis (PCA) and artificial neural network (ANN) showing good discrimination in the PCA score plot and a 99% classification accuracy rate of the implemented ANN model. The recorded spectra of the two fish indicated that tilapia has a higher fat content than Nile perch, as evidenced by higher CN and C2 bands and an atomic line at 247.8 nm in its spectrum. ...
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Fish products are essential sources of animal proteins and numerous nutrients required for healthy human nutrition worldwide. However, some types of low-priced fish may look very similar to some other expensive types, and usually, it is... more
Fish products are essential sources of animal proteins and numerous nutrients required for healthy human nutrition worldwide. However, some types of low-priced fish may look very similar to some other expensive types, and usually, it is not easy to differentiate between them for inexperienced customers. Moreover, in some markets, adulterating such high-priced fish types through its substitution by cheaper ones or mixing with bacterially spoiled ones, mostly when sold as fish fillets, is sometimes common. Certainly, fish microbial contamination in open markets represents serious hazards for people’s public health. Accordingly, seeking easy and fast fish fraud detection methods and their microbial contamination disclosure is crucial. Currently, available techniques are costly, time-consuming, and requiring special laboratories. In the present work, laser-induced fluorescence (LIF), as a spectrochemical analytical technique and diffuse optical measurements, has been used to discriminat...
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In the present work, nanoparticle-enhanced laser-induced breakdown spectroscopy was used to analyze an aluminum alloy. Although LIBS has numerous advantages, it suffers from low sensitivity and low detection limits compared to other... more
In the present work, nanoparticle-enhanced laser-induced breakdown spectroscopy was used to analyze an aluminum alloy. Although LIBS has numerous advantages, it suffers from low sensitivity and low detection limits compared to other spectrochemical analytical methods. However, using gold nanoparticles helps to overcome such drawbacks and enhances the LIBS sensitivity in analyzing aluminum alloy in the current work. Aluminum was the major element in the analyzed samples (99.9%), while magnesium (Mg) was the minor element (0.1%). The spread of gold nanoparticles onto the Al alloy and using a laser with different pulse energies were exploited to enhance the Al alloy spectral lines. The results showed that Au NPs successfully improved the alloy spectral lines intensity by eight times, which could be useful for detecting many trace elements in higher matrix alloys. Under the assumption of local thermodynamic equilibrium, the Boltzmann plot was used to calculate the plasma temperature. Be...
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Chlorophyll, the essential green pigment in plants, is considered a promising natural photosensitizer (PS) for photodynamic therapy (PDT). However, it suffers from lower stability in the physiological conditions that depress its efficacy... more
Chlorophyll, the essential green pigment in plants, is considered a promising natural photosensitizer (PS) for photodynamic therapy (PDT). However, it suffers from lower stability in the physiological conditions that depress its efficacy in the PDT. The combination of nanotechnology and PDT is becoming a promising approach to combat tumors. Gold nanoparticles (Au NPs), for example, are proposed as suitable carriers that can increase chlorophyll stability when conjugating together. In the present work, the impact of Au NPs conjugation in enhancing Chlorophyll b (Chl b) efficiency in the PDT of cancer cells has been emphasized. A chemical method using a natural product synthesized a novel Chlorophyll b-gold nanoparticles nanoconjugate (Chl b-Au NCs). The synthesized Chl b-Au NCs were characterized via UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Laser-Induced Fluorescence (LIF), Zeta potential, Dynamic light scattering (DLS), and Transmission electron microscopy (TEM). Chl b is characterized by a formyl group (CHO) which is absent in Chl a. This group leads to the formation of an electrostatic reaction between the positive charge of Chl b and the negative charge present on the surface of the gold nanoparticles. Moreover, Chlorophyll b loading on the biosynthesized gold nanoparticles (Au NPs) increases its photostability. The efficiency of the PDT was then studied on the MCF7 and the HepG2 cells using this conjugation. As a result, the prepared Chl b-Au NCs showed low dark toxicity, excellent photostability under laser irradiation of wavelength 650 nm, in addition to a significantly high PDT efficacy against tumor cells in vitro. This is due to the enhanced cellular uptake and the high reactive oxygen species (ROS) production upon laser irradiation. Therefore, the designed Chl b-Au NCs could be a very auspicious photo-therapeutic agent for enhancing cancer therapy in future clinical applications.
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In the present work, laser‐induced breakdown spectroscopy (LIBS) was used to differentiate between different black toners of printers and photocopiers based on their elemental composition. Measurements were performed on 23 toner samples... more
In the present work, laser‐induced breakdown spectroscopy (LIBS) was used to differentiate between different black toners of printers and photocopiers based on their elemental composition. Measurements were performed on 23 toner samples of different printers and six different photocopiers (of different brands and models). The LIBS spectra were compared to characterize each toner type. Multivariate statistical analysis based on PCA and graph clustering was used to develop a discrimination model between the toners in questioned documents. Good discrimination of both brand and model toners was obtained. The results may be beneficial for forensic applications in the investigations of questioned documents.
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The effect of the shape of the nanoparticles on the nanoparticle-enhanced LIBS (NELIBS) signal should be clarified.
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ABSTRACT A realistic estimate of the interionic potential that may account for the experimentally observed fusion rates (â10â»Â²Â³ deuterium-deuterium fusion/s) in palladium is presented. Moreover, some preliminary calorimetric studies... more
ABSTRACT A realistic estimate of the interionic potential that may account for the experimentally observed fusion rates (â10â»Â²Â³ deuterium-deuterium fusion/s) in palladium is presented. Moreover, some preliminary calorimetric studies on the hydrogen absorption process in palladium, performed in a cell with pressure up to 20 bars, are discussed. A detailed analysis of the sensitivity and calibration of the calorimetric system is also presented.
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An archeological Egyptian cartonnage dating back to the Greco-Roman period around the third century BC was elementally analyzed via the sample-friendly technique, Laser Induced Breakdown Spectroscopy (LIBS).
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Optical catapulting laser induced breakdown spectroscopy (OC-LIBS) is a new developing method and was successfully used for the analysis of solid aerosols. In the present work Bermuda Grass Smut Spores material in the form of fingerprint... more
Optical catapulting laser induced breakdown spectroscopy (OC-LIBS) is a new developing method and was successfully used for the analysis of solid aerosols. In the present work Bermuda Grass Smut Spores material in the form of fingerprint left on the glass support was used and analyzed using both OC-LIBS and conventional LIBS. Experimental conditions such the interpulse delay time between lasers, the effect of laser fluence on the emission lines intensities present in the fingerprint were investigated. A comparison between OC-LIBS and conventional LIBS for Bermuda was also performed. Moreover, conventional LIBS for glass only was conducted as a reference in the comparison between both methods. Advantages of OC-LIBS over conventional LIBS in terms of absence of contamination of the specimen analyzed and freedom from spectral contribution of the substrate where the sample was placed has been demonstrated in this research.
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In the present work we are presenting a detailed in vitro study of using laser-induced breakdown spectroscopy (LIBS) as a quick and simple method for spectrochemical analysis to identify and characterize some types of human malignancies.... more
In the present work we are presenting a detailed in vitro study of using laser-induced breakdown spectroscopy (LIBS) as a quick and simple method for spectrochemical analysis to identify and characterize some types of human malignancies. This has been performed via detection of the abundance of certain elements namely calcium and magnesium in malignant tissues with respect to the non-neoplastic ones. In order to improve the performance of the LIBS technique - in particular its sensitivity, reproducibility and limit of detection - the measurements have been performed under vacuum (10(-2) Torr) and the samples were frozen down to -196 degrees C in a specially designed vacuum chamber. Under such experimental arrangements a pronounced enhancement has been achieved in the signal to noise (S/N) ratio of different spectral lines. Significant discriminating results have been obtained in case of breast and colorectal cancers indicating the possibility of adopting LIBS in the early detection of the malignancy as well as the identification of the severity and the grade of the disease. The present work demonstrated that future in vivo measurements are also feasible and reliable using especial endoscopic systems for delivery of laser beam and collection of the emitted plasma light.
Research Interests: Chemistry, Analytical Chemistry, Breast Cancer, Calcium, Medicine, and 15 moreColorectal cancer, Humans, Magnesium, Lasers, Female, Cancer Diagnosis, Early Detection, Reproducibility, Spectrum analysis, Laser Induced Breakdown Spectroscopy, In Vitro Studies, C/N Ratio, Colorectal Neoplasms, Breast Neoplasms, and limit of detection
In order to analyze the emission spectrum of a laser-induced plasma for obtaining quantitative information on the abundance of the species present in the plasma it is necessary to study the local thermodynamic equilibrium (LTE) conditions... more
In order to analyze the emission spectrum of a laser-induced plasma for obtaining quantitative information on the abundance of the species present in the plasma it is necessary to study the local thermodynamic equilibrium (LTE) conditions in the plasma and determine the best conditions at which they are satisfied. In the present work Nd:YAG laser light pulses (lambda= 1064 nm, 6 ns) of different energies (25, 50, 75 and 100 mJ) are focused using a quartz lens (focal length 10 cm) onto certified aluminum alloy samples in air under atmospheric pressure. The emitted spectra are collected and analyzed using an echelle spectrometer coupled with an intensified charge coupled device camera. The temporal history of the plasma is obtained by recording the emission features at predetermined delays and at a fixed gate width (2500 ns). For each spectrum both electron density and excitation temperature are calculated for each delay time and laser pulse energy; we found that the values of the electron density are decreasing from 1018 to 1017 cm-3. The corresponding excitation temperatures were between 30000 and 4000 K depending on the laser pulse energy and the sample used. The LTE conditions were followed up for the different delays and different energies to determine the temporal range in which they are satisfied. It has been found that in the cases of 25- and 50-mJ laser energies, the LTE conditions were satisfied in the chosen delay range (500-5000 ns). On the other hand, for higher laser energies, the LTE conditions were critical at delay times less than 1500 ns and are satisfied for longer delays.
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Pulsed laser induced plasma (LIP) has a very short temporal existence. Due to the transient nature of the produced LIP, with a fast evolution of its characteristic parameters, these parameters are heavily dependent on the irradiation... more
Pulsed laser induced plasma (LIP) has a very short temporal existence. Due to the transient nature of the produced LIP, with a fast evolution of its characteristic parameters, these parameters are heavily dependent on the irradiation conditions such as incident laser intensity, irradiation spot size, ambient gas composition and pressure. It is also true that these parameters vary drastically with
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Analysis of the elemental composition of an object is a necessary step in the documentation of the properties of such object for estimating its condition. Metallic artworks are subjected to corrosion and oxidation processes due to... more
Analysis of the elemental composition of an object is a necessary step in the documentation of the properties of such object for estimating its condition. Metallic artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are recovered from excavation sites, as well as artefacts exposed to polluted air. Stabilization of the conservation state of these objects needs precise diagnostics of the accrued surface layers and identification of original, historical materials before further protective treatments, including safe laser cleaning of unwanted layers. This article describes in brief the basic principles and technological aspects of Laser-Induced Breakdown Spectroscopy (LIBS) (technique) applicability and prospects in the field of corrosion diagnostics.
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ABSTRACT Laser Induced Breakdown Spectroscopy (LIBS) is a well-known spectrochemical elemental analysis technique. In our investigations of the LIBS spectra it has been found that there is a remarkable correlation between the ionic to... more
ABSTRACT Laser Induced Breakdown Spectroscopy (LIBS) is a well-known spectrochemical elemental analysis technique. In our investigations of the LIBS spectra it has been found that there is a remarkable correlation between the ionic to atomic spectral lines emission ratio and the surface hardness of eggshell for two Different Broiler Breeder at different age. The proposed technique has been applied successfully in poultry science to estimate the age of broiler breeders by measuring the surface hardness of their eggshell. The experiments have been performed on two different strains, Arbor Acres plus (AAP) and Hubard Classic (HC), and the results were satisfactory.
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An archeological Egyptian cartonnage dating back to the Greco-Roman period around the third century BC was elementally analyzed via the sample-friendly technique, Laser-Induced Breakdown Spectroscopy (LIBS). The unique characteristics of... more
An archeological Egyptian cartonnage dating back to the Greco-Roman period around the third century BC was elementally analyzed via the sample-friendly technique, Laser-Induced Breakdown Spectroscopy (LIBS). The unique characteristics of LIBS as being a simple and fast technique, has been exploited to obtain surface elemental distribution and depth profiles for the investigated sample. An Nd:YAG laser operating at the fundamental wavelength of 1064 nm has been used as the excitation source along with an echelle spectrometer coupled to an ICCD detector for spectral dispersion and detection. Under the experimental conditions, four distinct regions were studied as ten elements were analyzed for spatial distribution along the surface and also for their depth profiles. Rapid and comprehensive visualization of the investigated regions are provided. The most relevant elements i.e. carbon, calcium, silicon, oxygen and iron suggest that the cartonnage was manufactured via the traditional met...
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ABSTRACT One of the most important aspects in laser cleaning of artworks is the possibility for on-line monitoring the cleaning process. This ensures that the cleaning intervention is satisfactory without any damage to the underlying... more
ABSTRACT One of the most important aspects in laser cleaning of artworks is the possibility for on-line monitoring the cleaning process. This ensures that the cleaning intervention is satisfactory without any damage to the underlying original surface. In this work it is shown that following and observing the integrated densities of the plumes generated during laser cleaning may be a simple, safe and straightforward methodology to monitor the removal process. A series of experiments on reference marble with simulated thick encrustation were considered to evaluate the plume monitoring technique. Parameters influencing the cleaning process and ablation threshold of the black crust (such as laser fluence, number of pulses etc.) were considered while the results were also evaluated under the microscope. The results of this study will be presented and discussed with the aim to establish accurate and reliable monitoring tools to follow the laser cleaning process.