No description available.

MnSi(111) films were grown on Si(111) substrates by solid phase epitaxy (SPE) and molecular beam epitaxy (MBE) to determine their magnetic structures. A lattice mismatch of -3.1% causes an in-plane tensile strain in the film, which is partially relaxed by misfit dislocations. A correlation between the thickness dependence of the Curie temperature (TC) and strain is hypothesized to be due to the presence of interstitial defects. The in-plane tensile strain leads to an increase in the unit cell volume that results in an increased TC as large as TC = 45 K compared to TC = 29.5 K for bulk MnSi crystals. The epitaxially induced tensile stress in the MnSi thin films creates an easy-plane uniaxial anisotropy. The magnetoelastic coefficient was obtained from superconducting quantum interference device (SQUID) magnetometry measurements combined with transmission electron microscopy (TEM) and x-ray diffraction (XRD) data. The experimental value agrees with the coefficient determined from density functional calculations, which supports the conclusion that the uniaxial anisotropy originates from the magnetoelastic coupling. Interfacial roughness obscured the magnetic structure of the SPE films, which motivated the search for a better method of film growth. MBE grown films displayed much lower interfacial roughness that enabled a determination of the magnetic structure using SQUID and polarized neutron reflectometry (PNR). Out-of-plane magnetic field measurements on MBE grown MnSi(111) thin films on Si(111) substrates show the formation of a helical conical phase with a wavelength of 2?/Q = 13.9 ± 0.1 nm. The presence of both left-handed and right-handed magnetic chiralities is found to be due to the existence of inversion domains that result from the non-centrosymmetric crystal structure of MnSi. The magnetic frustration created at the domain boundaries explains an observed glassy behaviour in the magnetic response of the films. PNR and SQUID measurements of MnSi thin films performed in an in-plane magnetic field show a complex magnetic behaviour. Experimental results combined with theoretical results obtained from a Dzyaloshinskii model with an added easy-plane uniaxial anisotropy reveals the existence of numerous magnetic modulated states that do not exist in bulk MnSi. It is demonstrated in this thesis that modulated chiral magnetic states can be investigated with epitaxially grown MnSi(111) thin films on insulating Si substrates, which offers opportunities to investigate spin-dependent transport in chiral magnetic heterostructures based on this system.

(ULSI) causes an increase of the resistance of the wiring system by increased scattering of electrons at side walls and grain boundaries in the state of the art Cu technology, which increases the RC delay of the interconnect system and thus degrades the performance of the device. The outstanding properties of carbon nanotubes (CNT) such as a large mean free path, a high thermal conductance and a large resistance against electromigration make them an ideal candidate to replace Cu in future feature nodes. The present thesis contributes to the preparation and properties of CNT based vertical interconnections (vias). In addition, all processes applied during the fabrication are compatible to ULSI and an interface between CNT based vias and a Cu metallization is studied. The methodology for the evaluation of CNT based vias is improved; it is highlighted that by measuring the resistance of one multiwall CNT and taking into account the CNT density, the performance of the CNT based vias can be predicted accurately. This provides the means for a systematic evaluation of different integration procedures and materials. The lowest contact resistance is obtained for carbide forming metals, as long as oxidation during the integration is avoided. Even though metal-nitrides exhibit an enhanced contact resistance, they are recommended to be used at the bottom metallization in order to minimize the oxidation of the metal-CNT contact during subsequent processing steps. Overall a ranking for the materials from the lowest to the highest contact resistance is obtained: Ta < Ti < TaN < TiN « TiO2 « Ta2O5 Furthermore the impact of post CNT growth procedures as chemical mechanical planarization, HF treatment and annealing procedures after the CNT based via fabrication are evaluated. The conductance of the incorporated CNTs and the applicable electrical transport regime relative to the CNT quality and the CNT length is discussed. In addition, a strong correlation between the temperature coefficient of resistance and the initial resistance of the CNT based vias at room temperature has been observed. / Die kontinuierliche Miniaturisierung der charakteristischen Abmessungen in hochintegrierten Schaltungen (ULSI) verursacht einen Anstieg des Widerstandes im Zuleitungssystem aufgrund der erhöhten Streuung von Elektronen an Seitenwänden und Korngrenzen in der Cu-Technologie, wodurch die Verzögerungszeit des Zuleitungssystems ansteigt. Die herausragenden Eigenschaften von Kohlenstoffnanoröhren (CNT), wie eine große mittlere freie Weglänge, hohe thermische Leitfähigkeit und eine starke Resistenz gegenüber Elektromigration machen diese zu einem idealen Kandidaten, um Cu in zukünftigen Technologiegenerationen zu ersetzen. Die vorliegende Arbeit beschreibt die Herstellung und daraus resultierenden Eigenschaften von Zwischenebenenkontakten (Vias) basierend auf CNTs. Alle verwendeten Prozessierungsschritte sind kompatibel mit der Herstellung von hochintegrierten Schaltkreisen und eine Schnittstelle zwischen den CNT Vias und einer Cu-Metallisierung ist vorhanden. Insbesondere das Verfahren zur Evaluierung von CNT Vias wurde durch den Einsatz verschiedener Methoden verbessert. Insbesondere soll hervorgehoben werden, dass durch die Messung des Widerstandes eines einzelnen CNTs, bei bekannter CNT Dichte, der Via Widerstand sehr genau vorausgesagt werden kann. Dies ermöglicht eine systematische Untersuchung des Einflusses der verschiedenen Prozessschritte und der darin verwendeten Materialien auf den Via Widerstand. Der niedrigste Kontaktwiderstand wird für Karbidformierende Metalle erreicht, solange Oxidationsprozesse ausgeschlossen werden können. Obwohl Metallnitride einen höheren Kontaktwiderstand aufweisen, sind diese für die Unterseitenmetallisierung zu empfehlen, da dadurch die Oxidation der leitfähigen Schicht minimiert wird. Insgesamt kann eine Reihenfolge beginnend mit dem niedrigsten zum höchsten Kontaktwiderstand aufgestellt werden: Ta < Ti < TaN < TiN « TiO2 « Ta2O5 Desweiteren wurde der Einfluss von Verfahren nach dem CNTWachstum wie die chemischmechanische Planarisierung, eine HF Behandlung und einer Temperaturbehandlung evaluiert, sowie deren Einfluss auf die elektrischen Parameter des Vias untersucht. Die Leitfähigkeit der integrierten CNTs und die daraus resultierenden elektrischen Transporteigenschaften in Abhängigkeit der CNT Qualität und Länge werden besprochen. Ebenso wird die starke Korrelation zwischen dem Temperaturkoeffizienten des elektrischen Widerstandes und des Ausgangswiderstandes der CNT basierten Vias bei Raumtemperatur diskutiert.

Rotavirus infection causes gastroenteritis, specifically severe gastroenteritis, affecting children younger than five globally, regardless of hygiene and water quality. Current licensed, live, attenuated vaccines do not contain the G9 genotype, which is a prevalent rotavirus strain circulating in sub-Saharan Africa, a region that carries a high rotavirus disease burden. Rotavirus-like particles (RV-VLPs) is an attractive non-live vaccine candidate, which has shown promising results in animal studies. Previously, dsRNA was extracted from a stool sample containing a South African human G9P[6] neonatal strain, and amplified cDNA using a sequence-independent procedure. The consensus sequence was obtained for the genome segments using 454® pyrosequencing. The insect-cell-codon-optimized genome segments 2 (VP2), 4 (VP4), 6 (VP6) and 9 (VP7) were cloned into a modified pFASTBACquad vector (pFBq). Several combinations of the genome segments were cloned to produce double-layered particles (DLP; pFBqVP2VP6) or triple-layered particles (TLP; pFBqVP2VP6VP7). In the current study, a ΔTLP (pFBqdVP2-VP8*VP6VP7) construct was generated. The first 92 amino acids of VP2 are not necessary for the conformation of recombinant RV-VLPs. The ORF of VP8*, which contains immune important epitopes, was fused to the 5’ end of the dVP2 coding region resulting in a dVP2-VP8* fused protein which was expressed in the presence of VP6 and VP7 to produce ΔTLPs. The Bac-to-Bac® Baculovirus Expression System and Spodoptera frugiperda (Sf) 9 insect cells were used for expression. All the proteins were successfully expressed. VP2, VP6, VP4 and the dVP2-VP8* fused protein were visible on Coomassie stained SDS-PAGE. Expression of VP7 could only be confirmed with western blot analysis. Particle formation, as assessed by transmission electron microscopy (TEM), was observed for DLPs. No TLPs of dVP2-8*/6/7 or VP2/6/7 were visualized due to the lower expression level of VP7 and the lack of calcium supplements during the assembly process. In conclusion, it was possible to produce RV-DLPs derived from the consensus sequence determined for a G9P[6] rotavirus directly from stool without prior propagation in cell culture or virus isolation. This strain contains both the G9 and P[6] genotypes that are currently prevalent in sub-Saharan Africa. / Thesis (MSc (Biochemistry))--North-West University, Potchefstroom Campus, 2013.

Rotavirus infection causes gastroenteritis, specifically severe gastroenteritis, affecting children younger than five globally, regardless of hygiene and water quality. Current licensed, live, attenuated vaccines do not contain the G9 genotype, which is a prevalent rotavirus strain circulating in sub-Saharan Africa, a region that carries a high rotavirus disease burden. Rotavirus-like particles (RV-VLPs) is an attractive non-live vaccine candidate, which has shown promising results in animal studies. Previously, dsRNA was extracted from a stool sample containing a South African human G9P[6] neonatal strain, and amplified cDNA using a sequence-independent procedure. The consensus sequence was obtained for the genome segments using 454® pyrosequencing. The insect-cell-codon-optimized genome segments 2 (VP2), 4 (VP4), 6 (VP6) and 9 (VP7) were cloned into a modified pFASTBACquad vector (pFBq). Several combinations of the genome segments were cloned to produce double-layered particles (DLP; pFBqVP2VP6) or triple-layered particles (TLP; pFBqVP2VP6VP7). In the current study, a ΔTLP (pFBqdVP2-VP8*VP6VP7) construct was generated. The first 92 amino acids of VP2 are not necessary for the conformation of recombinant RV-VLPs. The ORF of VP8*, which contains immune important epitopes, was fused to the 5’ end of the dVP2 coding region resulting in a dVP2-VP8* fused protein which was expressed in the presence of VP6 and VP7 to produce ΔTLPs. The Bac-to-Bac® Baculovirus Expression System and Spodoptera frugiperda (Sf) 9 insect cells were used for expression. All the proteins were successfully expressed. VP2, VP6, VP4 and the dVP2-VP8* fused protein were visible on Coomassie stained SDS-PAGE. Expression of VP7 could only be confirmed with western blot analysis. Particle formation, as assessed by transmission electron microscopy (TEM), was observed for DLPs. No TLPs of dVP2-8*/6/7 or VP2/6/7 were visualized due to the lower expression level of VP7 and the lack of calcium supplements during the assembly process. In conclusion, it was possible to produce RV-DLPs derived from the consensus sequence determined for a G9P[6] rotavirus directly from stool without prior propagation in cell culture or virus isolation. This strain contains both the G9 and P[6] genotypes that are currently prevalent in sub-Saharan Africa. / Thesis (MSc (Biochemistry))--North-West University, Potchefstroom Campus, 2013.

Der Einsatz nanostrukturierter Magnetmaterialien als Speicherschichten in Festplatten stellt ein vielversprechendes Konzept zur weiteren Erhöhung der erreichbaren Speicherdichten im Vergleich zu den heute eingesetzten granularen Medien dar. Für die Realisierung dieses Konzeptes ist eine detaillierte Kenntnis der Struktureigenschaften und deren Einfluss auf das magnetische Verhalten der einzusetzenden Schichten erforderlich. Für die vorliegende Arbeit wurden drei verschiedene magnetische Materialien ausgewählt und insbesondere mit elektronenmikroskopischen Methoden in struktureller Hinsicht untersucht. Dazu zählen ferromagnetische (FePt)(100-x)Cu(x) -Schichten, ferromagnetische [Co/Pt]n -Multilagen sowie ferrimagnetische Fe(100-x)Tb(x) -Schichten. Der Schwerpunkt der Untersuchungen lag dabei auf der Korrelation zwischen strukturellen und magnetischen Eigenschaften sowie im Einfluss der Nanostrukturierung auf das magnetische Verhalten der Schichten. In dieser Hinsicht wurden Aspekte der durch die Struktur bedingten magnetischen Anisotropie in Form von magnetokristalliner und Grenzflächenanisotropie betrachtet. Zudem wurde das Kopplungsverhalten zwischen einzelnen Strukturelementen in nanostrukturierten Schichten untersucht. Aufbauend auf die Untersuchung der drei genannten Materialien wurden [Co/Pt]n und Fe(100-x)Tb(x) ausgewählt zum Aufbau eines Systems mit zwei magnetischen Komponenten: Fe(80)Tb(20) / [Co/Pt]10. Die Untersuchungen konzentrierten sich dabei auf die Morphologie der Grenzfläche zwischen den beiden Bestandteilen und deren Einfluss auf den Exchange Bias, der in diesem System vorliegt.

This thesis focuses on the synthesis and characterisation of organoclays. X-ray diffraction has been used to study the changes in the basal spacings of montmorillonite clay and surfactant-intercalated organoclays. Variation in the d-spacing was found to be a step function of the surfactant concentration. Three different molecular environments for surfactant octadecyltrimethylammonium bromide (ODTMA) within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. High-resolution thermogravimetric analysis (HRTG) shows that the thermal decomposition of montmorillonite modified with ODTMA takes place in four steps attributing to dehydration of adsorbed water, dehydration of water hydrating metal cations, loss of surfactant and the loss of OH units respectively. In addition, it has shown that the decomposition procedure of DODMA and TOMA modified clays are very different from that of ODTMA modified ones. The surfactant decomposition takes place in several steps in the DODMA and TOMA modified clays while for ODTMA modified clays, it shows only one step for the decomposition of surfactant. Also TG was proved to be a useful tool to estimate the amount of surfactant within the organoclays. A model is proposed in which, up to 0.4 CEC, a surfactant monolayer is formed between the montmorillonite clay layers; up to 0.8 CEC, a lateral-bilayer arrangement is formed; and above 1.5 CEC, a pseudotrimolecular layer is formed, with excess surfactant adsorbed on the clay surface. While for dimethyldioctadecylammonium bromide (DODMA) and trioctadecylmethylammonium bromide (TOMA) modified clays, since the larger sizes of the surfactants, some layers of montmorillonite are kept unaltered because of steric effects. The configurations of surfactant within these organoclays usually take paraffin type layers. Thermal analysis also provides an indication of the thermal stability of the organoclay as shown by different starting decomposition temperatures. FTIR was used as a guide to determine the phase state of the organoclay interlayers as determined from the CH asymmetric stretching vibration of the surfactants to provide more information on surfactant configurations. It was used to study the changes in the spectra of the surfactant ODTMA upon intercalation into a sodium montmorillonite. Surfaces of montmorillonites were modified using ultrasonic and hydrothermal methods through the intercalation and adsorption of the cationic surfactant ODTMA. Changes in the surfaces and structure were characterized using electron microscopy. The ultrasonic preparation method results in a higher surfactant concentration within the montmorillonite interlayer when compared with that from the hydrothermal method. Both XRD patterns and TEM images demonstrate that SWy-2-Namontmorillonite contains superlayers. TEM images of organoclays prepared at high surfactant concentrations show alternate basal spacings between neighboring layers. SEM images show that modification with surfactant will reduce the clay particle aggregation. Organoclays prepared at low surfactant concentration display curved flakes, whereas they become flat with increasing intercalated surfactant. Fundamentally this thesis has increased the knowledge base of the structural and morphological properties of organo-montmorillonite clays. The configurations of surfactant in the organoclays have been further investigated and three different molecular environments for surfactant ODTMA within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. Changes in the spectra of the surfactant upon intercalation into clay have been investigated in details. Novel surfactant-modified montmorillonite results in the formation of new nanophases with the potential for the removal of organic contaminants from aqueous media and for the removal of hydrocarbon spills on roads.

This thesis describes the synthesis and characterisation of titania photocatalysts for incorporation into a polyethylene film. Monodisperse, anatase-phase titania nanoparticles are prepared and the synthesis conditions necessary for attraction to a laponite clay support are determined. Methods of preventing agglomeration of the laponite system such as the use of a polyethylene oxide surfactant or chemical modification of the laponite plate edges with a dimethyloctyl methoxysilane are also explored. Finally, photocatalytic studies on the laponite-supported titania nanoparticles are performed, and the compatibility and photoactivity of these materials in the polyethylene film are examined.

Characteristics of quantitative resistance in pea (Pisum sativum L.) to Erysiphe pisi DC, the pathogen causing powdery mildew, were investigated. Cultivars and seedlines of pea expressing quantitative resistance to E. pisi were identified and evaluated, by measuring the amounts of pathogen present on plant surfaces in field and glasshouse experiments. Disease severity on cv. Quantum was intermediate when compared with that on cv. Bolero (susceptible) and cv. Resal (resistant) in a field experiment. In glasshouse experiments, two groups of cultivars, one with a high degree of resistance and the other with nil to low degrees of resistance to E. pisi, were identified. This indicated either that a different mechanism of resistance applied in the two groups, or that there has been no previous selection for intermediate resistance. Several other cultivars expressing quantitative resistance were identified in a field experiment. Quantitative resistance in Quantum did not affect germination of E. pisi conidia, but reduced infection efficiency of conidia on this cultivar compared with cv. Pania (susceptible). Other epidemiological characteristics of quantitative resistance expression in Quantum relative to Pania were a 33% reduction in total conidium production and a 16% increase in time to maximum daily conidium production, both expressed on a colony area basis. In Bolero, the total conidium production was reduced relative to Pania, but the time to maximum spore production on a colony area basis was shorter. There were no differences between the cultivars in pathogen colony size or numbers of haustoria produced by the pathogen. Electron microscope studies suggested that haustoria in Quantum plants were smaller and less lobed than those in Pania plants and the surface area to volume ratios of the lobes and haustorial bodies were larger in Pania than in Quantum. The progress in time and spread in space of E. pisi was measured in field plots of cultivars Quantum, Pania and Bolero as disease severity (proportion of leaf area infected). Division of leaves (nodes) into three different age groups (young, medium, old) was necessary because of large variability in disease severity within plants. Disease severity on leaves at young nodes was less than 4% until the final assessment at 35 days after inoculation (dai). Exponential disease progress curves were fitted for leaves at medium nodes. Mean disease severity on medium nodes 12 dai was greatest (P<0.001) on Bolero and Pania (9.3 and 6.8% of leaf area infected respectively), and least on Quantum (1.6%). The mean disease relative growth rate was greatest (P<0.001) for Quantum, but was delayed compared to Pania and Bolero. Gompertz growth curves were fitted to disease progress data for leaves at old nodes. The asymptote was 78.2% of leaf area infected on Quantum, significantly lower (P<0.001) than on Bolero or Pania, which reached 100%. The point of inflection on Quantum occurred 22.8 dai, later (P<0.001) than on Pania (18.8 dai) and Bolero (18.3 dai), and the mean disease severity at the point of inflection was 28.8% for Quantum, less (P<0.00l) than on Pania (38.9%) or Bolero (38.5%). The average daily rates of increase in disease severity did not differ between the cultivars. Disease progress on Quantum was delayed compared with Pania and Bolero. Disease gradients from inoculum foci to 12 m were detected at early stages of the epidemic but the effects of background inoculum and the rate of disease progress were greater than the focus effect. Gradients flattened with time as the disease epidemic intensified, which was evident from the large isopathic rates (between 2.2 and 4.0 m d⁻¹) Some epidemiological variables expressed in controlled environments (low infection efficiency, low maximum daily spore production and long time to maximum spore production) that characterised quantitative resistance in Quantum were correlated with disease progress and spread in the field. These findings could be utilised in pea breeding programmes to identify parent lines from which quantitatively resistant progeny could be selected.

Κατά τις τελευταίες δεκαετίες παρατηρείται συνεχής αύξηση της έντασης του φαινομένου του θερμοκηπίου γεγονός που προκαλεί σημαντικές συνέπειες στο περιβάλλον και στη ζωή μας γενικότερα. Συνεπώς, είναι απαραίτητη η μείωση της ανθρωπογενούς εκπομπής των αερίων που συμβάλλουν στην αύξηση του φαινομένου αυτού. Η εκμετάλλευση και χρήση των δύο πιο σημαντικών θερμοκηπικών αερίων, του μεθανίου και του διοξειδίου του άνθρακα, μπορεί να επιτευχθεί με την αναμόρφωση του CH4 με CO2 ή αλλιώς ξηρή αναμόρφωση του μεθανίου (Dry Reforming of Methane-DRM). Με τη διεργασία DRM τα δύο συγκεκριμένα αέρια μετατρέπονται σε αέριο σύνθεσης (synthesis gas), το οποίο χρησιμοποιείται είτε για τη σύνθεση πληθώρας οργανικών ενώσεων, είτε για την παραγωγή Η2 για ενεργειακούς σκοπούς. Η DRM παρουσιάζει σημαντικά πλεονεκτήματα: δεν απαιτείται η χρήση ύδατος, φθηνό σχετικά κόστος εγκαταστάσεων, χρησιμοποιείται σε χημικά συστήματα μεταφοράς ενέργειας, ενώ και το αέριο σύνθεσης που παράγεται έχει ακόμα κατάλληλη αναλογία για συνθέσεις Fischer–Tropsch. Παρόλα αυτά η DRM δεν έχει εκτεταμένη βιομηχανική εφαρμογή επειδή αντιμετωπίζει ένα σημαντικό μειονέκτημα: ο καταλύτης μετά από κάποιο χρόνο λειτουργίας απενεργοποιείται λόγω του άνθρακα που αποτίθεται πάνω του. Στην παρούσα εργασία μελετήθηκε ο state of the art καταλύτης Ni/Al2O3, τον οποίο τροποποιήσαμε με βόριο σε διάφορους λόγους [Β/(B+Νi)] με κύριο στόχο τη μείωση των ανθρακούχων αποθέσεων. Οι τροποποιημένοι καταλύτες συντέθηκαν με τη μέθοδο του υγρού συνεμποτισμού και χαρακτηρίστηκαν φυσικοχημικά με διάφορες τεχνικές, ώστε να μελετήσουμε την επίδραση του βορίου στην υφή τους (ΒΕΤ, porosimetry, SEM, TEM), στη δομή τους (XRD, UV-Vis DRS) και στην αναγωγιμότητά τους (H2-TPR). Η καταλυτική συμπεριφορά τους για την αντίδραση της ξηρής αναμόρφωσης του μεθανίου αξιολογήθηκε σε αντιδραστήρα σταθερής κλίνης, για 24h, σε συνθήκες: 973Κ, 1 atm, τροφοδοσία 50%CH4-50%CO2. Ο άνθρακας που αποτέθηκε στους χρησιμοποιημένους καταλύτες μετρήθηκε με τη μέθοδο της θερμοπρογραμματισμένης υδρογόνωσης (TPH). Τα ανηγμένα και χρησιμοποιημένα στην DRM καταλυτικά δείγματα μελετήθηκαν επίσης με ηλεκτρονικό μικροσκόπιο σάρωσης (SEM με αναλυτή EDS) και ηλεκτρονικό μικροσκόπιο διαπερατότητας (ΤΕΜ). Βρέθηκε ότι η παρουσία του Β μειώνει σημαντικά την ποσότητα του αποτιθέμενου άνθρακα στους καταλύτες Ni/Al2O3, σε ποσοστό έως και 86%, χωρίς να επηρεάζει ιδιαίτερα τη δραστικότητα και την εκλεκτικότητα των καταλυτών. Σημαντικό ρόλο παίζει το ποσοστό του Β στον καταλύτη, με τον καταλύτη με λόγο Β/(B+Νi) = 0,5 να εμφανίζει τη βέλτιστη συμπεριφορά. Τα αποτελέσματα μας έδειξαν ότι η ιδιαίτερη θετική επίδραση του βορίου οφείλεται κυρίως στο γεγονός ότι ευνοεί τη διασπορά του μεταλλικού νικελίου. Τροποποίηση με βόριο, σε κατάλληλη περιοχή φορτίσεων, του καταλύτη Ni/Al2O3 μεγιστοποιεί το πλήθος των νανοσωματιδίων νικελίου με μέση διάσταση < 6.0 nm, τα οποία, ως γνωστόν, ελαχιστοποιούν την απόθεση άνθρακα. / The intensity of the greenhouse effect is constantly increasing in the last few decades with an adverse effect both on the environment and the humanity. In order to decrease the effect, human-caused emissions should be minimized. The two most important greenhouse gases, methane and carbon dioxide, can be used in the DRM (Dry Reforming of Methane) process. With this process the above mentioned gases are converted to synthesis gas, which is then used for the synthesis of a great number of organic compounds and synthetic fuels (through the Fisher-Tropsch syntheses) or for the production hydrogen to be used as a fuel (energy purposes). The DRM process presents a number of advantages, namely: no water is required, relatively low cost of process plants,it can be used as a Chemical Energy Transfer System and, finally, the produced synthesis gas has adequate CO/H2 ratio for Fisher-Tropsch syntheses. Although DRM is a promising process, its industrial application is hindered by a major drawback: the catalysts are rapidly deactivating due to coking. In the current study, the state of the art catalyst Ni/Al2O3 was studied and modified with boron, using different ratios of Β/(B+Νi). Our primary objective was to reduce coking. The modified catalysts were synthesized by wet co-impregnation and physicochemically characterized in their oxidic, reduced and used forms, using various techniques, in order to investigate the influence of boron on the texture (BET, Porosimetry, SEM, TEM), structure (XRD, UV-Vis DRS) and reducibility (H2-TPR) of the catalysts. The catalytic performance for the DRM process was studied under stable conditions (973Κ, 1 atm and 50%CH4-50%CO2 undiluted feed), for 24h, using a fixed bed reactor. Carbonaceous deposits on the used catalysts were determined by Temperature Programmed Hydrogenation (TPH). Scanning Electron Microscopy (SEM) with EDS analyser and Transmission Electron Microscopy (TEM) were also used in the study of reduced and used catalytic samples. Modifying Ni/Al2O3 catalysts with boron results in a great decrease of the deposited coke (up to 86%), without any significantly influence on the activity and selectivity of the catalysts. A major factor influencing the catalyst is the B loading, with the ratio Β/(B+Νi)=0,5 giving the best results. Boron’s positive effect was mainly attributed to its ability to increase Ni dispersion. Modification of Ni/Al2O3 catalysts, by using the appropriate boron loading, resulted to an increase of the amount of nickel nanoparticles with an average dimension under 6.0 nm, which are known to minimize coke deposition.