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11.
Coz A Mantzavinos D Karageorgos P Kalogerakis N Andrés A Viguri JR Irabien A 《Annali di chimica》2006,96(9-10):505-514
The study of the ecotoxicity in two industrial waste materials and the relationships with the organic parameters has been conducted. Foundry sludge and olive mill waste have been used as industrial waste materials with organic or mixed character. Stabilisation/solidification (S/S) and advanced oxidation (AOP) processes have been carried out in order to treat both foundry sludge and olive mill waste. Analysis of ecotoxicity, total organic carbon, COD and phenol index have been evaluated in the untreated waste and end-products. The results of the treated samples allow obtaining the best formulations in both processes. The best formulations in the immobilisation process have been obtained with Portland cement and black carbon, activated carbon or foundry sand ashes. In the AOP process, ozone concentrations above 35 mg/l and reaction times equal to 120 minutes have been the optimal variables. The relationships between the organic parameters and the ecotoxicity of the samples have been studied in this paper. Furthermore, the global organic parameters have been studied in relation to the phenolic compounds. Lineal and logarithmic expressions have been obtained between the total organic carbon and phenol index and the ecotoxicity of the samples related to the organic parameters, respectively. Ecotoxicity of the samples with Vibrio fischeri is recommended as a very promising biotest for the study of the characterisation and the evaluation of the treatment of organic and mixed character waste and total organic carbon is recommended as global organic parameter in the treatment of foundry sludge. 相似文献
12.
Spiros Kostopoulos Konstantinos Sidiropoulos Dimitris Glotsos Emmanouil Athanasiadis Konstantina Boutsikou Eleftherios Lavdas Georgia Oikonomou Ioannis V. Fezoulidis Marianna Vlychou Michael Hantes Dionisis Cavouras 《Magnetic resonance imaging》2013
The aim was to design a pattern-recognition (PR) system for discriminating between normal and pathological knee articular cartilage of the medial femoral (MFC) and tibial condyles (MTC). The data set comprised segmented regions of interest (ROIs) from coronal and sagittal 3-T magnetic resonance images of the MFC and MTC cartilage of young patients, 28 with abnormality-free knee and 16 with pathological findings. The PR system was designed employing the probabilistic neural network classifier, textural features from the segmented ROIs and the leave-one-out evaluation method, while the PR system's precision to “unseen” data was assessed by employing the external cross-validation method. Optimal system design was accomplished on a consumer graphics processing unit (GPU) using Compute Unified Device Architecture parallel programming. PR system design on the GPU required about 3.5 min against 15 h on a CPU-based system. Highest classification accuracies for the MFC and MTC cartilages were 93.2% and 95.5%, and accuracies to “unseen” data were 89% and 86%, respectively. The proposed PR system is housed in a PC, equipped with a consumer GPU, and it may be easily retrained when new verified data are incorporated in its repository and may be of value as a second-opinion tool in a clinical environment. 相似文献
13.
N. Kalivas I. Valais D. Nikolopoulos A. Konstantinidis A. Gaitanis D. Cavouras C.D. Nomicos G. Panayiotakis I. Kandarakis 《Applied Physics A: Materials Science & Processing》2007,89(2):443-449
Phosphor materials are used in medical imaging combined with radiographic film or other photodetectors. Cerium (Ce3+) -doped scintillators are of particular interest for medical imaging, because of their very fast response. YAP:Ce scintillator-based
image detectors have already been evaluated in single-crystal form and under conditions of positron emission tomography and
synchrotron or γ-ray irradiation. Furthermore, YAP:Ce phosphor has been evaluated in conjunction with radiographic films.
The present work reports experimental and theoretical data concerning the light output absolute luminescence efficiency (AE)
of the YAP:Ce screens under irradiation conditions employed in medical X-ray projection imaging (i.e., in diagnostic radiology).
projection imaging (i.e., in diagnostic radiology). YAP:Ce phosphor screens with surface densities ranging between 53 and
110 mg/cm2 were prepared by sedimentation on fused silica substates in our laboratory. The resulted surface density of the screens was
determined by dividing the phosphor mass deposited on the screen surface with the area of the surface. Additionally this work
addresses the imaging performance of YAP:Ce by estimation of the detective quantum efficiency (DQE), i.e., the square of the
signal to noise ratio transfer. Absolute efficiency was found to decrease with X-ray tube voltage for for YAP:Ce phosphor.
The highest experimental efficiency was obtained for the 53.7 mg/cm2 and 88.0 mg/cm2 YAP:Ce screens. The highest DQE value was found for the 88.0 mg/cm2 screen irradiated at 60 kVp.
PACS 81.05.Zx; 87.59.-e; 87.57.Ce 相似文献
14.
Natalia Domenikou Ioannis Thanopulos Dionisis Stefanatos Vassilios Yannopapas Emmanuel Paspalakis 《Annalen der Physik》2023,535(2):2200478
A theoretical investigation on the population transfer in a Λ-type quantum system near a spherical gold nanoparticle under application of two stimulated Raman adiabatic passage (STIRAP) shortcuts and efficiency comparison with conventional STIRAP. It combines the density matrix approach for system dynamics, with classical electromagnetic calculations used to obtain the modified electric field amplitudes of the applied pulses and the Purcell factor of the quantum system due to the presence of the nanoparticle. The efficiency of population transfer is investigated by varying the distance between the quantum system and the nanoparticle, the free-space decay rate of quantum states, the mutual polarization, and the Rabi frequencies of each STIRAP shortcut pulses. In all cases, at least one of the applied shortcuts is more efficient than conventional STIRAP, while in most cases both perform better. When the pump and Stokes fields of the shortcuts have radial and tangential polarizations with respect to the nanoparticle surface, respectively, high transfer efficiency is obtained for small distances of the quantum system to the nanoparticle, moderate free space decay rates and large Rabi frequencies of the fields, while when the pulse polarizations are interchanged, the transfer becomes highly efficient only at large distances. 相似文献
15.
I. Kandarakis D. Cavouras C.D. Nomicos G.S. Panayiotakis 《Applied physics. B, Lasers and optics》1999,68(6):1121-1124
This study presents a method to evaluate the imaging performance of phosphor materials used in medical imaging systems. The
advantage of the method is that phosphor evaluation is performed independently of the optical detectors (films, photocathodes,
photodiodes) used in radiation detectors to capture phosphor light. The method is based on the noise-equivalent-quanta (NEQ)
concept, which provides an index of the signal-to-noise ratio (SNR) associated with the diagnostic value of a medical image.
NEQ was expressed as a function of the phosphor’s emitted light wavelength, light energy flux, and modulation transfer function
(MTF). All these parameters are related to intrinsic phosphor properties such as effective atomic number, density, activator
ion. The method was tested on three yttrium-based phosphors, two of them activated with europium (Eu3+) and one with terbium (Tb3+). Results showed that europium-activated phosphors (Y2O2S:Eu, Y2O3:Eu) exhibited improved SNR, whereas the terbium phosphor (Y2O2S:Tb) had better MTF.
Received: 11 August 1998 / Revised version: 4 January 1999 / Published online: 10 March 1999 相似文献
16.
Eleftheriou Georgios Tsabaris Christos Papageorgiou Dimitra K. Patiris Dionisis L. Androulakaki Effrosini G. Pappa Filothei K. 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):655-671
Journal of Radioanalytical and Nuclear Chemistry - Chronological records and sedimentation rates of coastal sediment cores from different aquatic environments of NE Mediterranean are reported.... 相似文献
17.
We have undertaken explicit solvent molecular dynamics simulations to investigate the preferential stabilization of the silicate octamer Si(8)O(20)(8-) over the hexamer Si(6)O(15)(6-) in relation with the ability of tetramethylammonium (TMA) to form an adsorption layer around these cage-like polyions. We have found that the hexamer cannot support such a layer and as a result is vulnerable to hydrolysis. The dynamics of TMA desorption off the surface of the hexamer is investigated in connection with the solvent dynamics. We have studied the energetics of this preferential stabilization by calculating the relative change in the free energies of formation between the complexes Si(8)O(20)(8-).8TMA and Si(6)O(15)(6-).6TMA and found the former to be more stable by 70 kcal/mol. We also find that the energetics are consistent with experimental data, suggesting that the hexamer is a long-lived metastable species. Furthermore, we have studied the solvent structure and dynamics in the vicinity of both the bare polyions and their complexes with TMA. We have found that, as anticipated, both the octamer and the hexamer participate in hydrogen bonds with the water molecules, regardless of whether a TMA adsorption layer exists or not. In fact, we find that the presence of a TMA adsorption layer has a rather profound effect on the stability of these hydrogen bonds-it increases their lifetime by at least a factor of 2 relative to that of the hydrogen bonds between water and the bare polyions. 相似文献
18.
N.?Kalivas L.?Costaridou I.?Kandarakis D.?Cavouras C.D.?Nomicos G.?PanayiotakisEmail author 《Applied Physics A: Materials Science & Processing》2004,78(6):915-919
Phosphor materials are used in medical imaging combined with radiographic film or other photodetectors. A parameter for choosing a phosphor material is the number of light photons produced per absorbed X-ray energy E, i.e. phosphor gain. Traditionally, a parameter for choosing the best photodetector for a phosphor material is the spectral matching factor, which denotes the percentage of the optical photons detected by the photodetector. However, this factor does not account for the phosphor gain neither in terms of signal strength nor in terms of noise. In this paper a new factor is introduced which evaluates phosphor-photodetector combinations in terms of optical gain signal-to-noise ratio matching. The proposed factor was implemented to some phosphor-photodetector combinations. It was found that for the narrow band emitting phosphors studied the results of the new factor and the matching factor were numerically the same. However, when not narrow bandwidth emitting phosphors were considered the results were numerically different. Additionally, for the case of CsI:Na phosphor different results were obtained in combinations ranking. PACS 78.65; 42.80 相似文献
19.
N. Kalivas L. Costaridou I. Kandarakis D. Cavouras C.D. Nomicos G. Panayiotakis 《Applied Physics A: Materials Science & Processing》1999,69(3):337-341
The quality of a medical image depends, among other parameters, on quantum noise. Quantum noise is affected by the fluctuations
in the number of optical quanta produced within the phosphor, per absorbed X-ray (i.e. phosphor intrinsic-gain fluctuations).
This effect is considered by means of a factor, called in this study intrinsic-gain noise factor, IGNF(E). In existing theoretical
models of quantum noise, the corresponding factor is taken to be equal to one. In this paper, an expression that accounts
for the coefficient of variation of the phosphor intrinsic gain is introduced. This expression takes into account the process
of electron–hole pair conversion to optical photons and the frequency distribution function of the emitted optical photon
energy. Subsequently IGNF(E) is expressed in terms of this coefficient of variation. IGNF(E) has been calculated for several
phosphors and for various energies. For all medical X-ray energies studied, phosphors that exhibit a high relative fluctuation
of emitted optical photon energy, IGNF(E) exceeds by 2% to over 17% the corresponding factor of the existing theoretical models
of quantum noise.
Received: 25 March 1999 / Accepted: 29 March 1999 / Published online: 14 July 1999 相似文献
20.
Athanasios A. Koutinas Argyro Bekatorou Eleftheria Katechaki Dimitra Dimitrellou Nikolaos Kopsahelis Harris Papapostolou Panayiotis Panas Kostas Sideris Mihalis Kallis Loulouda A. Bosnea Dionisis Koliopoulos Panayiotis Sotiropoulos Ageliki Panteli Yiannis Kourkoutas Maria Kanellaki Magdalini Soupioni 《Applied biochemistry and biotechnology》2010,160(6):1734-1743
This paper concerns the effect of thermal-drying methodology on the investment cost for dried kefir cells production in order to be used as starter culture in cheese manufacturing. Kefir cells were produced at pilot plant scale using a 250-L bioreactor and whey as the main substrate. Kefir cells were subsequently dried in a thermal dryer at 38?°C and used as a starter culture in industrial-scale production of hard-type cheeses. The use of thermally dried kefir as starter culture accelerated ripening of cheeses by increasing both lipolysis and fermentation rate as indicated by the ethanol, lactic acid, and glycerol formation. Additionally, it reduced coliforms and enterobacteria as ripening proceeded. This constituted the basis of developing an economic study in which industrial-scale production of thermally dried kefir starter culture is discussed. The industrial design involved a three-step process using three bioreactors of 100, 3,000, and 30,000 L for a plant capacity of 300 kg of thermally dried kefir culture per day. The cost of investment was estimated at 238,000 €, which is the 46% of the corresponding cost using freeze-drying methodology. Production cost was estimated at 4.9 €/kg of kefir biomass for a 300-kg/day plant capacity, which is the same as with the corresponding cost of freeze-dried cells. However, the estimated added value is up to 10.8?×?109 € within the European Union. 相似文献