scholarly journals Terahertz Frequency Continuous-Wave Spectroscopy and Imaging of Explosive Substances

ISRN Optics ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Michael A. Startsev ◽  
Abdulhakem Y. Elezzabi
Keyword(s):  
Continuous Wave ◽  
Solid Phase ◽  
Spectral Characteristics ◽  
Thz Radiation ◽  
Line Broadening ◽  
Experimental Conditions ◽  
Explosive Materials ◽  
Raster Scan ◽  
Security Screenings ◽  
Frequency Radiation

Continuous-wave terahertz (THz) radiation spectroscopy was performed on high explosive materials using a tuneable optical parametric oscillator (OPO). Military grade, solid-phase, explosive substances, such as cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate (PETN), and composition-4, were spectrally scanned over the 0.7–1.9 THz frequency range under experimental conditions modeling that of “real-world” security screenings. Spectral peak locations and spectral line broadening effects were quantified using a Lorentz lineshape fit algorithm. The full-width half-maximum (FWHM) parameter computed by the Lorentz fit algorithm was shown to help in the identification of samples with broad and sparse spectral characteristics. A concealed explosives identification scheme was demonstrated through raster scan THz frequency radiation imaging at specific OPO tuning frequencies.

scholarly journals Comparative investigation of lasing and amplification performance in cryogenic Yb:YLF systems

2021 ◽  
Vol 127 (3) ◽  
Author(s):  
Umit Demirbas ◽  
Martin Kellert ◽  
Jelto Thesinga ◽  
Yi Hua ◽  
Simon Reuter ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Estimation Method ◽  
Laser Cavity ◽  
Comparative Investigation ◽  
Limiting Factor ◽  
Experimental Conditions ◽  
Temperature Estimation ◽  
Transverse Temperature ◽  
First Time

AbstractWe present detailed experimental results with cryogenic Yb:YLF gain media in rod-geometry. We have comparatively investigated continuous-wave (cw) lasing and regenerative amplification performance under different experimental conditions. In the cw lasing experiments effect of crystal doping, cw laser cavity geometry and pump wavelength on lasing performance were explored. Regenerative amplification behavior was analyzed and the role of depolarization losses on performance was investigated. A recently developed temperature estimation method was also employed for the first time in estimating average crystal temperature under lasing conditions. It is shown that the thermal lens induced by transverse temperature gradients is the main limiting factor and strategies for future improvements are discussed. To the best of our knowledge, the achieved results in this study (375 W in cw, and 90 W in regenerative amplification) are the highest average powers ever obtained from this system via employing the broadband E//a axis.

Synthesis of [1-β-mercaptopropionic acid, 8-D-arginine]vasopressin (DDAVP) in solid phase. Simple optimalization

1979 ◽  
Vol 44 (4) ◽  
pp. 1173-1178 ◽  
Author(s):  
Viktor Krchňák ◽  
Milan Zaoral
Keyword(s):  
Arginine Vasopressin ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Experimental Conditions ◽  
Phase Synthesis ◽  
Mercaptopropionic Acid ◽  
Better Than

A series of solid-phase syntheses of the protected precursor II of DDAVP was carried out. Experimental conditions were developed under which practically pure II can reproducibly be obtained in yields better than 60%. The protected precursors of DDAVP obtained by liquid- and solid-phase synthesis and DDAVP samples obtained from these precursors were undistinguishable by conventional analytical or pharmacological assays.

Influence of biomass on hydrodynamics of an internal loop airlift reactor

2006 ◽  
Vol 60 (6) ◽  
Author(s):  
M. Juraščík ◽  
M. Hucík ◽  
I. Sikula ◽  
J. Annus ◽  
J. Markoš
Keyword(s):  
Aspergillus Niger ◽  
Gluconic Acid ◽  
Solid Phase ◽  
Biomass Concentration ◽  
Airlift Reactor ◽  
Phase System ◽  
Two Phase ◽  
Experimental Conditions ◽  
Internal Loop ◽  
Three Phase

AbstractThe effect of the biomass presence on the overall circulation velocity, the linear velocities both in the riser and the downcomer and the overall gas hold-up was studied in a three-phase internal loop airlift reactor (ILALR). The measured data were compared with those obtained using a two-phase system (air—water). All experiments were carried out in a 40 dm3 ILALR at six different biomass concentrations (ranging from 0 g dm−3 to 7.5 g dm−3), at a temperature of 30°C, under atmospheric pressure. Air and water were used as the gas and liquid model media, respectively. Pellets of Aspergillus niger produced during the fermentation of glucose to gluconic acid in the ILALR were considered solid phase. In addition, liquid velocities were measured during the fermentation of glucose to gluconic acid using Aspergillus niger. All measurements were performed in a bubble circulation regime. At given experimental conditions the effect of the biomass on the circulation velocities in the ILALR was negligible. However, increasing of the biomass concentration led to lower values of the total gas hold-up.

Use of headspace solid-phase microextraction to characterize odour compounds in subsurface flow constructed wetland for wastewater treatment

2004 ◽  
Vol 49 (9) ◽  
pp. 89-98 ◽  
Author(s):  
Y. Huang ◽  
L. Ortiz ◽  
J. García ◽  
P. Aguirre ◽  
R. Mujeriego ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Solid Phase Microextraction ◽  
Volatile Fatty Acids ◽  
Solid Phase ◽  
Subsurface Flow ◽  
Threshold Concentration ◽  
Medium Size ◽  
Experimental Conditions ◽  
Headspace Solid Phase Microextraction ◽  
Odorous Compounds

A headspace solid-phase microextraction (HS-SPME) preconcentration method was applied to the analysis of some of the major odorous compounds occurring in wastewater using GC/MS or GC/NPD detection. The detection limit for volatile amines, volatile fatty acids, and volatile alkylsulphides ranged from 3 to 100, 2 to 150, and 0.0006 to 0.035 μg/L, respectively. The SPME method was used to examine the fate of odorous compounds in the subsurface flow constructed wetlands (SFCW) operated under different hydraulic loading rate (HLR), bed aspect ratio, and granular medium size. Among the experimental conditions evaluated in the SFCW beds, HLR was found to be the most important factor influencing the evolution of the studied compounds. There were also significant differences among bed types in the behaviour of ammonia (NH3), acetic acid (Ac), isovaleric acid (IsoA), propionic acid (PrA), and dimethylsulphide. Aspect ratio and medium granular size were minor factors influencing SFCW performance. The major odour compounds by mass in the effluent of SFCW with different operational conditions were NH3 and Ac. Further removal of these two compounds is considered as very important from the viewpoint of chemical composition. On the other hand, Relative Odour Intensity (ROI: ratio between the absolute concentration to the odour threshold concentration) suggested that PrA and IsoA were the two major compounds responsible for odour intensity. Thus, further removal of these two compounds is viewed as very important for the effluent deodorization, especially for PrA. From our results, this compound appears to be produced by processes occurring in the SFCW.

The Microstructure of Nanocrystalline Powders from Line Profile Analysis

2004 ◽  
Vol 443-444 ◽  
pp. 71-76 ◽  
Author(s):  
Nathalie Audebrand ◽  
Daniel Louër
Keyword(s):  
Line Profile ◽  
Profile Analysis ◽  
Theoretical Background ◽  
Nanocrystalline Powders ◽  
Line Profile Analysis ◽  
Line Broadening ◽  
Experimental Conditions ◽  
Profile Fitting ◽  
Propagation Of Errors ◽  
Structure Imperfection

The theoretical background currently used in line profile analysis is reviewed. It covers the size and structure imperfection effects at the origin of diffraction line broadening. The propagation of errors, i.e. old errors and new errors related to profile fitting techniques, is commented. The experimental conditions for minimising errors are described. Representative examples of microstructure characterisation of nanopowders are presented.

Microstructure Morphology and Mechanical Properties of Steel 30CrMnSiNi2A Irradiated by Continuous Wave Laser

2014 ◽  
Vol 809-810 ◽  
pp. 369-376
Author(s):  
Tao Tao Wu ◽  
Li Jun Wang ◽  
Cheng Hua Wei ◽  
Chun Xu Pan ◽  
Lin Zhu Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Laser Irradiation ◽  
Continuous Wave ◽  
Solid Phase ◽  
Irradiation Time ◽  
Coupling Efficiency ◽  
Temperature History ◽  
Brittle Layer ◽  
Microstructure Morphology ◽  
Morphology And Mechanical Properties

Steel 30CrMnSiNi2A slices were irradiated by a continuous wave fiber laser beam with the intensity of 14.5W/cm2. Alloy samples with various temperature processes were obtained by changing the laser irradiation time, irradiation times and atmosphere environment. X-ray diffraction, scanning electron microscope, energy dispersive spectrometer and nanoindentation system were employed to characterize their microstructure morphology and mechanical properties. Three layers were observed in the samples fracture, namely oxide film, hard brittle layer and alloy substrate. The hard brittle layer had a higher hardness and a lower toughness compared with the base metal. Referring to the temperature history, we deemed that the surface oxidation and the solid phase transformation were the main factors which changed laser coupling efficiency. The results also illuminated the correlation between the microstructure morphology and the response to laser irradiation of the samples.

Design and Implementation of an Intensified Coprecipitation Reactor for the Treatment of Liquid Radioactive Wastes

2013 ◽  
Author(s):  
Julie Flouret ◽  
Yves Barré ◽  
Hervé Muhr ◽  
Edouard Plasari
Keyword(s):  
Reaction Zone ◽  
Residence Time ◽  
Flow Rate ◽  
High Efficiency ◽  
Solid Phase ◽  
Continuous Process ◽  
Decontamination Factor ◽  
Barium Nitrate ◽  
Molar Ratio ◽  
Experimental Conditions

The coprecipitation is a robust and inexpensive process for the treatment of important volumes of low and intermediate radioactive level liquid wastes. Its major inconvenient is the huge volume of sludge generated. The purpose of this work is to optimize the industrial coprecipitation continuous process by achieving the following objectives: - maximize the decontamination efficiency; - minimize the volume of sludge generated by the process; - reduce the treatment cost decreasing the installation volume. An innovative reactor with an infinite recycling ratio was therefore designed. It is a multifunctional reactor composed of two zones: a perfectly mixed precipitation zone and a classifier to perform liquid-solid separation. The experiments are focused on the coprecipitation of strontium by barium sulphate. The effluent containing sulphate ions and the barium nitrate solution are injected in the reaction zone where strontium and barium coprecipitate as sulphates. The produced solid phase is returned into the reaction zone by the classifier and goes out slowly from the reactor bottom with a residence time much higher than the liquid phase. This creates both a high concentration of solid phase in the reaction zone and a high efficiency of decontamination. The experimental conditions simulate the industrial effluents. The total treatment flow rate is 17 L/h, with an effluent flow rate of 16 L/h and a reactive flow rate of 1 L/h, hence a mean residence time of 10 minutes. In these experimental conditions, the molar ratio sulphate/barium after mixing corresponds to 4.9. These conditions are used in the reprocessing plant of La Hague. The decontamination factor reached in these experimental conditions is excellent: DF = 1500. The decontamination factor obtained with the classical continuous process is only equal to 60. Different process parameters are studied in order to optimize the reactor/classifier: residence time, barium nitrate flow rate and racking flow rate. The decrease of barium nitrate flow rate reduces the volume of sludge generated by the process keeping a high efficiency of strontium decontamination: DF = 400. An excess of sulphate is necessary to perform an efficient decontamination, but the molar ratio sulphate/barium can be reduced to 3 instead of 4.9 used industrially. The reactor/classifier also represents an efficient device for the coprecipitation process intensification. Indeed, it can sensibly reduce the final installation size while treating important volume of effluents. This innovative reactor optimizes both the decontamination efficiency of radioactive liquid wastes and the reduction of sludge volume. A reduction of sulphate ions in the discharge is also possible, which is environmentally friendly.

scholarly journals High efficiency photomodulators for millimeter wave and THz radiation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
I. R. Hooper ◽  
N. E. Grant ◽  
L. E. Barr ◽  
S. M. Hornett ◽  
J. D. Murphy ◽  
...  
Keyword(s):  
High Efficiency ◽  
Continuous Wave ◽  
Broad Band ◽  
Cost Effective ◽  
Silicon Wafers ◽  
Thz Radiation ◽  
Limiting Factor ◽  
Switching Speed ◽  
Carrier Lifetimes ◽  
Narrow Frequency Band

AbstractPhotomodulators for mm-wave and THz radiation are an essential component for many imaging and signal processing applications. While a myriad of schemes have been devised to enhance photomodulation by enhancing the light-matter interaction, there has been less focus on the photoconductive materials themselves, which are often the limiting factor. Here, we present an approach to increase the photomodulation efficiency of silicon by orders of magnitude, using post treatment of off-the-shelf silicon wafers. The increase in efficiency removes the need for bulky and costly amplified laser sources, and creates the potential for compact and cost-effective modulators for real-world applications. By passivating the surfaces of long bulk-lifetime silicon wafers with Al2O3, the recombination of the photoexcited carriers at the surfaces is mostly eliminated. This results in vastly longer excess carrier lifetimes (up to ~50 ms), with corresponding increases in photoconductivity. The resulting modulators are highly efficient, with the transmission through them being reduced from ~90% to <10% over a narrow frequency band with a continuous wave excitation intensity of just 10 Wm−2, whilst modulation factors of greater than 80% can be achieved over a broad band with similar intensities. We also discuss the limitations of such long-lifetime modulators for applications where the switching speed or spatial resolution of a modulator may be critical.

scholarly journals Razvoj SPE-HPLC-DAD metode za određivanje florfenikola i florfenikol amina u cerebrospinalnoj tekućini svinja

2020 ◽  
Vol 51 (2) ◽  
pp. 129-138
Author(s):  
Ksenija Šandor ◽  
Svjetlana Terzić ◽  
Anja Vujnović ◽  
Eleonora Perak Junaković ◽  
Irena Žarković ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
High Performance ◽  
Solid Phase ◽  
Biological Fluids ◽  
Experimental Period ◽  
Intramuscular Administration ◽  
Array Detector ◽  
Control Group ◽  
Pharmacokinetic Studies ◽  
Experimental Conditions

A study of florfenicol (FF) and its metabo- lite florfenicol amine (FFA) in pig cerebrospinal fluid was conducted following repeated intramuscular administration of the original (reference) and a generic veterinary medicinal product (VMP) under the same experimental conditions (20 mg FF/kg body weight, 48-hour interval). Both VMPs are solutions for injection containing FF as an active substance in the concentration of 300 mg/mL and have been authorized in Croatia for use in cattle and pigs. In this study, clinically healthy pigs were randomly divided into three groups. The first group was treated with the reference VMP, the second with the generic VMP, while the third served as the control group. Animals were sacrificed at 216, 288 and 384 hours after the first drug administration. Cerebrospinal fluid samples were analysed by the optimized and validated high-performance liquid chromatography-diode array detector method (HPLC-DAD). The solid-phase extraction (SPE) technique was chosen for sample preparation. The HPLC-DAD method provides good linearity over the concentration range of 0.05 to 5.00 μg/mL for FF and FFA. Limits of detection were 0.0023 μg/mL for FF and 0.0100 μg/mL for FFA. Extraction recoveries of FF were from 86.6% to 111.8%, and of FFA from 91.7% to 98.8%. The SPE-HPLC-DAD method has been demonstrated to be a selective, sensitive and suitable analytical method for the determination of FF and FFA in cerebrospinal fluid. The present study was based on a preliminary study that quantified FF in pig plasma at 216 hours after the first application of reference or generic VMP. However, FF and FFA were not detected in any of the cerebrospinal fluid samples during the experimental period. According to the nature of biological fluids, the SPE-HPLC-DAD method can be suitable for further pharmacokinetic studies of FF in pig plasma and serum after intramuscular administration of VMPs.

scholarly journals Availability of Nickel in Soil Evaluated by Various Chemical Extractants and Plant Accumulation

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1805
Author(s):  
Monika Jakubus ◽  
Małgorzata Graczyk
Keyword(s):  
Fly Ash ◽  
Sequential Analysis ◽  
Solid Phase ◽  
Nickel Content ◽  
Cultivated Plants ◽  
Risk Assessment Code ◽  
Experimental Conditions ◽  
Bioconcentration Factors ◽  
Bcr Method ◽  
Quantitative Changes

This work presents quantitative changes of nickel in soil and plants under the influence of compost and fly ash. The research was carried out in a 3-year experiment on medium soil fertilised with compost or fly ash. The plants: narrow leaf lupine (Lupinus angustifolius L.), camelina (Camelina sativa L.), and oat (Avena sativa L.) were planted in consecutive years. The soil from the experiment was subjected to extraction by sequential analysis with the Community Bureau of Reference (BCR) method, and single extractions using 1 mol·dm−3 HCl and DTPA solutions, obtaining the amount of nickel in various combinations with the soil solid phase. Total contents of the metal in soil and cultivated plants were determined. On the basis of Ni contents in the soil and cultivated plants, the bioconcentration factors and the risk assessment code were calculated. The type of amendments had a significant impact on the nickel content in lupine, for camelina and oat was the greatest in the control conditions. The differences between the amounts of Ni determined for bioconcentration factors were significant and depended on the amendments and nickel obtained by different methods. Regardless of the experimental conditions, the amount of Ni in the exchangeable bonds (Fr. I) had the greatest impact on the content of Ni in lupine and oat, whereas NiDTPA in the case of camelina.

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