Search

Sodium molybdate is evaluated as corrosion inhibitor for steel in brackish water; it is encapsulated by interfacial polymerization and the produced capsules are characterized. Electrochemical impedance spectroscopy and corrosion potential measurements were used to determine the short-time corrosion inhibition while polarization curves were used for the estimation of the inhibition efficiency. The capsules composition, the Na 2 MoO 4 content and the release rate are then determined. Na 2 MoO 4 shows corrosion inhibition for at least 15 h. Capsules consist of polyurea and polyurethane which are formed due to the reaction of the isocyanates with the water of the emulsion and the used surfactants, respectively. Most of the inhibitor is released within 90 min. Electrochemical Impedance Spectroscopy and Scanning Vibrating Electrode Technique show corrosion inhibition on artificially damaged areas for the coatings containing the corrosion inhibitor capsules.

This work studies the influence of the proportional change in discharge power and the monomer feed on the morphology and the chemistry of atmospheric plasma deposited films. Atmospheric plasma coatings of allyl methacrylate were deposited using dielectric barrier discharge plasma under different conditions but always under the same ratio between the discharge power and monomer feed (W/FM). It is shown that a constant W/FM does not necessarily provide the same chemistry and the same morphology for atmospheric pressure plasma. This is explained by the higher discharge power of the plasma resulting in an increase of streamers which alter the distribution of energy among the plasma species. On the surface of the deposited coatings, globular-like features were observed, which are suggested to be formed in the volume of the discharge. The deposition rate is also influenced. providing thicker coatings, when high monomer feed/high power are used. Finally, infrared spectra showed a higher retention of the ester functionality at high power/high monomer feed.

3-Aminopropyltriethoxysilane coatings have been deposited on stainless steel (SS) samples by means of an atmospheric pressure dielectric barrier discharge as an adhesive promotion layer in epoxy resin/SS composites. A multi-diagnostic analytical approach (FTIR, XPS) was used for the chemical characterization of the deposited coating with regard to improvement of adhesively bonded joint strength. The effect of a plasma post-treatment after the plasma coating deposition was compared to a thermal post-treatment. Both enhanced the siloxane networking resulting in a significant adhesion improvement. Fracture strength between SS and epoxy was increased with more than 20 MPa.

By positioning the layer containing Ce ( dbp ) 3 close to the coating–metal interface, the effective use of the inhibitor is promoted, as the leaching out towards the metal surface is facilitated. The chemical nature of Ce ( dbp ) 3 did not undergo any significant change due to the plasma discharge. The coatings with Ce ( dbp ) 3 were compared with equivalent coatings without incorporated corrosion inhibitor and it was shown that Ce ( dbp ) 3 improved the corrosion performance when the coating was mechanically damaged. Optical evaluation of the coatings showed a significant decrease in the corrosion, especially in the area under the coating. However, the low corrosion resistance values obtained by electrochemical impedance spectroscopy indicate that corrosion was not inhibited all over the scribed area.

This work deals with the in-situ mass spectrometric (MS) characterization of gases during the atmospheric pressure plasma-enhanced chemical vapor deposition of propyl isobutyrate (PiB) and allylmethacrylate (AMA). By monitoring the fragments of interest, we are trying to understand the mechanisms involved in the plasma synthesis of acrylate-like coatings. For instance, while CO2+ drastically increases when a PiB/argon plasma is ignited, it decreases in the case of AMA. This trend also appears for other fragments, which leads to the conclusion that while PiB seems to suffer from fragmentation, AMA oligomerizes into the gas phase, resulting in a better protection of the ester functionality. Mass spectrometry is used for the in-situ characterization of gases during the atmospheric pressure plasma-enhanced chemical vapor deposition of propyl isobutyrate (PiB) and allylmethacrylate (AMA), only differing by the number of unsaturations. We highlight a different behavior of AMA which tends to oligomerize in the gas phase while PiB deposits by a fragmentation/recombination mechanism. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this study, we investigated the atmospheric plasma polymerization of allyl methacrylate (AMA), n-propyl methacrylate (nPMA), and propyl isobutyrate (PiB), whose chemistry mainly differs by their number of unsaturations. The resulting material is characterized using X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS) whilethethickness ofthecoatingsis determined byvisiblespectroscopic ellipsometry(Vis-SE). The results show that the concentration of ester groups at the surface of the plasma polymers, as well as their deposition rate strongly depends on the surrounding unsaturations present in the precursor. A stabilization of the ester groups and an increase in the deposition rate due to the carbon‐carbon double bonds is

This work deals with the plasma-deposition of allyl methacrylate (AMA) and acrylic acid (AA) on metallic substrates. The plasma setup used is an atmospheric pressure radio frequency (RF) torch. Infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS) are used as characterization tools. In addition, spectroscopic ellipsometry (SE) has been used to control the thickness and calculate the corresponding deposition rates. Whereas the surface chemistry of plasma deposited AMA does not seem to be influenced by the plasma power, acrylic acid based coatings are strongly degraded with the increasing power. AMA seems to allow an efficient polymerization, while at the same time is particularly resistant to plasma induced fragmentation in the range of power used. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2,2,4,4,6,8,8-Heptamethylnonane (HMN), a saturated branched hydrocarbon precursor, is deposited by means of atmospheric plasma DBD. Hydrophobic coatings starting from this precursor which is liquid at room temperature can be obtained. The degree of polymerization of the coating seems to be dependent on the amount of provided precursor. The coatings were characterized by FTIR, TOF-SIMS, WCA, SE, and XPS. The plasma deposition of the liquid, highly branched saturated precursor 2,2,4,4,6,8,8-heptamethylnonane (HMN) by means of an atmospheric pressure dielectric barrier is reported. The obtained coatings are hydrophobic and the chemical structure suggests a low fragmentation of the precursor. Increasing the amount of precursor not only favors the deposition rate but also seems to favor a better crosslinking in the deposited coating. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Allyl methacrylate (AMA) was deposited on aluminium using atmospheric dielectric barrier discharge plasma. AMA posseses two C=C bonds which have very different reactivities and the efficiency of the plasma on polymerising the two different kinds of double bonds was evaluated. The Fourier transform infrared spectra and the nuclear magnetic resonance spectra of the plasma coatings were compared with those of conventionally synthesised poly(AMA). The influence of the monomer feed on the ester, the vinyl and the allyl functionalities of the coatings were investigated. Plasma coatings showed lower concentration of non-reacted allyl groups than conventional poly(AMA) suggesting a more cross-linked network. Pull-off adhesion tests were performed after the deposition of the a topcoat to evaluate the potential use of the AMA based coatings as adhesion promoter. Allyl methacrylate deposited using atmospheric dielectric barrier discharge plasma. Infrared and nuclear magnetic resonance spectroscopy show that both allyl and vinyl moieties are polymerised during deposition. This suggests a formation of a crosslinked organic film that can be used as intermediate between aluminium and polyester topcoat. Pull-off tests show a promising adhesion performance. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The change in emphasis of European food policy toward legislative certification schemes has shifted the research agenda toward investigating the link between the concept of “territory” and food product perceptions. However, a relatively neglected aspect of this literature is the exploratory qualitative work investigating consumer perceptions of “symbolic” and, to a lesser extent, a broader range of “extrinsic” cues within territorial products. More importantly, there is a dearth of equivalent research subjecting these exploratory findings to rigorous quantitative analysis. Accordingly, our paper addresses this weakness in the literature, examining the perceptual inter-relationships between a broad range of intrinsic, extrinsic and symbolic cues by deriving underlying product dimensions. Consumer segments based on these product dimensions are derived and profiled using an array of socio-economic, lifestyle and product knowledge variables. Finally, marketing policy conclusions are drawn.

This work deals with the in-situ mass spectrometric (MS) characterization of gases during the atmospheric pressure plasma-enhanced chemical vapor deposition of propyl isobutyrate (PiB) and allylmethacrylate (AMA). By monitoring the fragments of interest, we are trying to understand the mechanisms involved in the plasma synthesis of acrylate-like coatings. For instance, while CO2+ drastically increases when a PiB/argon plasma is ignited, it decreases in the case of AMA. This trend also appears for other fragments, which leads to the conclusion that while PiB seems to suffer from fragmentation, AMA oligomerizes into the gas phase, resulting in a better protection of the ester functionality.

Bimetallic Pt–Cu carbon-supported catalysts (Pt(Cu)/C) were prepared by electroless deposition of Cu on a high surface area carbon powder support, followed by its partial exchange for Pt; the latter was achieved by a galvanic replacement process involving treatment of the Cu/C precursor with a chloroplatinate solution. X-ray diffraction characterization of the Pt(Cu)/C material showed the formation of Pt-rich Pt–Cu alloys. X-ray photoelectron spectroscopy revealed that the outer layers are mainly composed of Pt and residual Cu oxides, while metallic Cu is recessed into the core of the particles. Repetitive cyclic voltammetry in deaerated acid solutions in the potential range between hydrogen and oxygen evolution resulted in steady-state characteristics similar to those of pure Pt, indicating the removal of residual Cu compounds from the surface (due to electrochemical treatment) and the formation of a compact Pt outer shell. The electrocatalytic activity of the thus prepared Pt(Cu)/C material toward methanol oxidation was compared to that of a commercial Pt/C catalyst as well as of similar Pt(Cu)/C catalysts formed by simple Cu chemical reduction. The Pt(Cu)/C catalyst prepared using Cu electroless plating showed more pronounced intrinsic catalytic activity toward methanol oxidation than its counterparts and a similar mass activity when compared to the commercial catalyst. The observed trends were interpreted by interplay between mere surface area effects and modification of Pt electrocatalytic performance in the presence of Cu, both with respect to methanol oxidation and poisonous CO removal.

A two-step procedure at room temperature was applied to prepare a bimetallic Pt-Cu carbon-supported catalyst (Pt-Cu/C). First the chemical reduction of Cu ions by sodium borohydride in the presence of Vulcan XC72R carbon powder is performed. Second, the partial galvanic replacement of Cu particle layers by Pt is achieved upon immersion in a chloroplatinate solution. The characterisation of the Pt-Cu/C catalyst by XRD and XPS proves the formation of Pt-Cu alloying. The electrochemical active surface area (EASA) is determined for the Pt-Cu/C transmetalation catalyst as well as for a commercial Pt/C catalyst from the Alfa Aesar HiSpec ® product line. The resemblance in surface voltammetry is an indication for a Pt rich shell. The catalytic activity towards the oxygen reduction reaction for both catalysts is evaluated by using linear sweep voltammetry (LSV) in combination with a rotating disc electrode. Koutechý–Levich analysis shows that the Pt-Cu/C catalyst has a higher catalytic activity towards the oxygen reduction reaction (ORR) at 0.8 V and 0.85 V vs RHE compared to the tested commercial catalyst. The activity increase is attributed to a “ligand effect”-modification of the core metal on the Pt shell.

In this study, we investigated the atmospheric plasma polymerization of allyl methacrylate (AMA), n-propyl methacrylate (nPMA), and propyl isobutyrate (PiB), whose chemistry mainly differs by their number of unsaturations. The resulting material is characterized using X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS) while the thickness of the coatings is determined by visible spectroscopic ellipsometry (Vis-SE). The results show that the concentration of ester groups at the surface of the plasma polymers, as well as their deposition rate strongly depends on the surrounding unsaturations present in the precursor. A stabilization of the ester groups and an increase in the deposition rate due to the carbon–carbon double bonds is suggested.

XX

The change in emphasis of European food policy toward legislative certification schemes has shifted the research agenda toward investigating the link between the concept of 'territory' and food product perceptions. However, a relatively neglected aspect of this literature is the exploratory qualitative work investigating consumer perceptions of 'symbolic' attributes within territorial products. More importantly, there is a dearth of equivalent research subjecting these exploratory findings to rigorous quantitative analysis. Accordingly, this paper addresses this weakness in the literature examining the perceptual inter-relationships between a broad range of intrinsic, extrinsic and symbolic cues by deriving underlying product dimensions. Consumer segments based on these product dimensions are derived and profiled using an array of socio-economic, lifestyle and product knowledge variables. Finally, marketing policy conclusions are drawn.

Μεταπτυχιακή διατριβή που υποβλήθηκε στη σχολή ΜΗΧΟΠ του Πολυτεχνείου Κρήτης για την πλήρωση προϋποθέσεων λήψης του μεταπτυχιακού διπλώματος ειδίκευσης:"Γεωτεχνολογία και Περιβάλλον". Περίληψη: Ο προσδιορισμός του χρόνου της πρώτης άφιξης σε σεισμικά δεδομένα είναι απαραίτητος για την εκτέλεση υπολογισμών στατικής διόρθωσης ή υπολογισμούς τομογραφίας καθοδικών κυμάτων (diving wave tomography). Η επιλογή των χρόνων πρώτων αφίξεων είναι ένα πρόβλημα αναγνώρισης μοτίβων και ως εκ τούτου συνεπάγεται σημαντική ανθρώπινη προσπάθεια. Επιπλέον, καθώς αυξάνεται ο αριθμός των σεισμικών αισθητήρων, γίνεται όλο και πιο δύσκολο για τους αναλυτές να επιλέξουν σεισμικές φάσεις τόσο χειροκίνητα όσο και αναλυτικά, παρόλα αυτά οι προσπάθειες αυτές είναι θεμελιώδεις. Παρά τις βελτιώσεις που έγιναν τα τελευταία χρόνια με τις μεθόδους αυτόματης επιλογής πρώτων αφίξεων, εξακολουθεί να είναι πολύ δύσκολο να προσομοιαστούν τα αποτελέσματα που προκύπτουν από έμπειρους αναλυτές, με ένα πιο λεπτό ζήτημα να είναι το γεγονός ότι διάφοροι γεωφυσικοί αναλυτές επιλέγουν πρώτες αφίξεις με διαφορετικούς τρόπους, κάτι που μπορεί να εισάγει μεροληψία (bias) στα δεδομένα. Από τα παραπάνω γίνεται φανερό ότι πρέπει να εισαχθεί ένας πιο αξιόπιστος και ακριβής τρόπος αυτόματης επιλογής χρόνου διαδρομής. Με τη χρήση των νευρωνικών δικτύων που γίνονται όλο και πιο δημοφιλή στις γεωφυσικές εφαρμογές, λόγω των δυνατοτήτων τους ως καθολικών προσεγγιστών (global approximators), είναι δηλαδή εργαλεία που μπορούν να προσεγγίσουν οποιαδήποτε συνεχή συνάρτηση με ακρίβεια και ως εκ τούτου καθιστούν έναν πολύ ελπιδοφόρο τρόπο αυτόματης επιλογής πρώτων αφίξεων επεξεργασίας σεισμικών δεδομένων. Σε αυτή την εργασία, εισάγονται και επεξεργάζονται σεισμικά δεδομένα και στη συνέχεια εκπαιδεύονται τεχνητά νευρωνικά δίκτυα. Επιλέγεται το δίκτυο με τις καλύτερες επιδόσεις και χρησιμοποιείται για την αυτόματη επιλογή των συμβάντων πρώτης άφιξης σε σεισμικά δεδομένα. Χρησιμοποιώντας την έξοδο του νευρωνικού δικτύου έναντι της εξόδου από έναν έμπειρο χρήστη, προκύπτουν χρήσιμα συμπεράσματα. Έχοντας ένα μεγαλύτερο σύνολο δεδομένων εισόδου βελτιώνεται η απόδοση του δικτύου και ο αριθμός των κόμβων συμβάλλει θετικά στα αποτελέσματα, αλλά μετά από ένα συγκεκριμένο σημείο δεν υπάρχει περαιτέρω βελτίωση Summarization: The time of the first-arrival in seismic data, is essential for performing refraction statics computations or diving-wave tomography calculations. Picking first-arrival times, is a pattern recognition problem and, as such, involves a substantial amount of human effort. Furthermore, with the number of seismic sensors growing, it is becoming increasingly difficult for analysts to pick seismic phases both, manually and comprehensively, yet such efforts are fundamental. Despite the improvements made in recent years with the automatic phase picking methods, it is still very difficult to match the performance of experienced analysts, with a subtler issue being the fact that, different seismic analysts may pick phases in different ways, which most of the times can introduce bias in the data. From the above it becomes obvious that a more reliable and accurate way of automated phase picking needs to be introduced. With the use of neural networks becoming increasingly popular in geophysical applications, because of their abilities as universal approximators, they are tools that can approximate any continuous function with an arbitrary precision, and as such they make for a very promising way to automatically pick first break events and edit seismic trace data. In this thesis, a number of seismic data is imported, edited and then a number of neural networks is trained. The best performing one is chosen and used to automatically pick first break events on seismic data. Using the neural network’s output against the output from an experienced user, useful conclusions are derived. Having a larger input data set improves the output of the network and the number of nodes positively contributes to the output, but after a certain point there is no improvement.

Προπτυχιακή διπλωματική εργασία. Περίληψη: Αντικείμενο της διπλωματικής αυτής εργασίας είναι η ανάπτυξη μεθόδου επεξεργασίας θαλασσιών σεισμικών δεδομένων, με σκοπό την απομάκρυνση των ανακλάσεων που προέρχονται από την θαλασσιά επιφάνεια (φαινόμενο ghost). Το φαινόμενο αυτό παρουσιάζεται στις θαλάσσιες διασκοπήσεις επειδή η επιφάνεια της θάλασσας φέρεται σαν ένας τέλειος ακουστικός καθρέπτης και δημιουργεί επιφανειακές ανακλάσεις. Το αποτέλεσμα του φαινομένου αυτού είναι να εμφανίζονται ετεροχρονισμένες, ως προς τις ανακλάσεις που προέρχονται από τους σχηματισμούς, καταγραφές, αυξάνοντας την χρονική διάρκεια των ανακλάσεων και υποβαθμίζοντας την χρονική ανάλυση των δεδομένων. Για την επίτευξη του στόχου της εργασίας, αναπτύχθηκε ειδική μεθοδολογία στο λογισμικό Matlab™. Η μεθοδολογία αυτή, βασίστηκε στην τεχνολογία, διπλού αισθητήρα, της εταιρίας θαλάσσιων γεωφυσικών ερευνών, PGS. Η τεχνολογία αυτή κάνει χρήση 2 συνιστωσών καταγραφής των υδροφώνων, της πίεσης (P) και της κατακόρυφης ταχύτητας μετατόπισης (Vz) με σκοπό την απαλοιφή των επιφανειακών ανακλάσεων από τις καταγραφές. Αναλυτικότερα τα βασικά στάδια υλοποίησης της παρούσας μελέτης συνοψίζονται στα εξής: Αρχικά πραγματοποιήθηκε δημιουργία συνθετικών σεισμικών δεδομένων, με βάση πραγματικά δεδομένα από ένα τμήμα σεισμικής τομής της σεισμικής γραμμής AEG-1 μήκους περίπου 25km. Η γραμμή αυτή βρίσκεται πλησίον των νήσων Φολέγανδρος και Σίφνος, εντός της λεκάνης της Φολεγάνδρου. Στην συνέχεια αναπτύχθηκε μέθοδος επεξεργασίας σε περιβάλλον Matlab™ για την απομάκρυνση των ανακλάσεων από την θαλάσσια επιφάνεια και εφαρμόσθηκε στα συνθετικά δεδομένα. Ακολούθησε συμβατική επεξεργασία των δεδομένων όπου πραγματοποιήθηκε αναδιάταξη των καταγραφών κοινής πηγής σε δεδομένα κοινού ενδιάμεσου σημείου, διόρθωση της κανονικής χρονικής απόκλισης και σεισμική χωροθέτηση. Τα αποτελέσματα από την εφαρμογή της μεθόδου για την απομάκρυνση επιφανειακών ανακλάσεων, αξιολογήθηκαν και έγινε σύγκριση τους με αντίστοιχα από συνθετικό μοντέλο. Το μοντέλο αυτό δημιουργήθηκε με την χρήση ορίων απορρόφησης στην ανώτερη επιφάνεια του με αποτέλεσμα να μην παράγει επιφανειακές ανακλάσεις (φαινόμενο ghost). Συμπερασματικά, με τη μέθοδο αυτή, προκύπτουν υψηλής ευκρίνειας συνθετικά δεδομένα, απαλλαγμένα ως επί το πλείστων από επιφανειακές ανακλάσεις (φαινόμενο ghost). Τα συνθετικά αυτά δεδομένα μπορούν να χρησιμοποιηθούν σαν βάση για την καλύτερη ερμηνεία και κατανόηση των πραγματικών δεδομένων που λαμβάνονται από την περιοχή μελέτης.

3-Aminopropyltriethoxysilane coatings have been deposited on stainless steel (SS) samples by means of an atmospheric pressure dielectric barrier discharge as an adhesive promotion layer in epoxy resin/SS composites. A multi-diagnostic analytical approach (FTIR, XPS) was used for the chemical characterization of the deposited coating with regard to improvement of adhesively bonded joint strength. The effect of a plasma post-treatment after the plasma coating deposition was compared to a thermal post-treatment. Both enhanced the siloxane networking resulting in a significant adhesion improvement. Fracture strength between SS and epoxy was increased with more than 20 MPa

Pt–Ni particles supported on Vulcan XC72R carbon powder have been prepared by a combination of crystalline Ni electroless deposition and its subsequent partial galvanic replacement by Pt upon treatment of the Ni/C precursor by a solution of chloroplatinate ions. The Pt-to-Ni atomic ratio of the prepared catalyst has been confirmed by EDS analysis to be ca. 1.5:1. No shift of Pt XPS peaks has been observed, indicating no significant modification of its electronic properties, whereas the small shift of the corresponding X-ray diffraction (XRD) peaks indicates the formation of a Pt-rich alloy. No Ni XRD peaks have been observed in the XRD pattern, suggesting the existence of very small pockets of Ni in the core of the particles. The surface electrochemistry of electrodes prepared from the catalyst material suggests the existence of a Pt shell. A moderate increase in intrinsic catalytic activity towards methanol oxidation in acid has been observed with respect to a commercial Pt catalyst, but significant mass specific activity has been recorded as a result of Pt preferential confinement to the outer layers of the catalyst nanoparticles.

Pt–Ni particles supported on Vulcan XC72R carbon powder have been prepared by a combination of crystalline Ni electroless deposition and its subsequent partial galvanic replacement by Pt upon treatment of the Ni/C precursor by a solution of chloroplatinate ions. The Pt-to-Ni atomic ratio of the prepared catalyst has been confirmed by EDS analysis to be ca. 1.5:1. No shift of Pt XPS peaks has been observed, indicating no significant modification of its electronic properties, whereas the small shift of the corresponding X-ray diffraction (XRD) peaks indicates the formation of a Pt-rich alloy. No Ni XRD peaks have been observed in the XRD pattern, suggesting the existence of very small pockets of Ni in the core of the particles. The surface electrochemistry of electrodes prepared from the catalyst material suggests the existence of a Pt shell. A moderate increase in intrinsic catalytic activity towards methanol oxidation in acid has been observed with respect to a commercial Pt catalyst, but significant mass specific activity has been recorded as a result of Pt preferential confinement to the outer layers of the catalyst nanoparticles.