Magnetic Behavior of Cobalt Atoms at Long Copper Chains Studied with Scanning Tunneling Microscopes

Over the last decades, with the help of low-temperature scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), the magnetic and electronic properties of magnetic atoms were studied on metal substrates and insulating layers. Depending on the underlying substrates, scientists were able to focus on their physical phenomenon of interest. When a magnetic atom is in direct contact with a metallic substrate, its interaction with the bath of conduction electrons of the host metal leads to many-body quantum effects such as the Kondo effect. Several experiments were performed to study the evolution of the Kondo effect with changing the atomic environment of a localized spin. Despite the great results obtained from these experiments, a fully understood picture still remains a challenge. A practical way to simplify the study of adatoms on solids is to reduce the interaction of the deposited atom with the conduction electron bath by an insulating layer. Using decoupling layers such as Cu2N, Al2O3, and MgO the magnetic behavior of Fe, Mn, and Co adatoms were studied. Obtaining a large magnetic anisotropy energy (MAE) for these systems was a great achievement to tailor magnetism in the smallest levels. However, still one of the challenging tasks in magnetism is maximizing the MAE for transition metal systems. In this work, by using the ability of STM to create dislocations in crystals, the difficult and time-consuming procedure of fabricating nano-structures by atom manipulation has been avoided. Long Cu chains up to 200 nm were fabricated and used to study the Kondo effect of Co adatom. By attaching Co atom to a monatomic Cu chain, its asymmetric Kondo resonance altered to a resonance symmetric with respect to Fermi energy. Further study of the observed symmetric resonance in the presence of an external magnetic field revealed its inelastic excitation origin. By choosing a proper atomic environment for Co adatoms, we were able to modify its quenched orbital momentum, demonstrate the effect of the spin-orbit coupling on its energy spectrum and obtain a noticeable MAE. Moreover, among the fabricated dislocations, we also observed chains and vacancy lines with different widths. They provided the opportunity to study the apparent tunneling barrier height (Φapp) in scanning tunneling microscopy. The variation of experimental Φapp for these nano-structures was not as expected by theory. A kinetic energy contribution to the tunneling process is proposed to be the reason of the unexpected experimental Φapp trend. Furthermore, by means of atom manipulation and STS, the role of surface state electrons in the Kondo effect of Co adatoms has been investigated; a topic with contradictory experimental observations. Using a step edge of a crystal to modulate the surface local density of states, we observed a negligible variation of the Kondo resonance width. This shows a minor role of surface state electrons in this many-body process.In den letzten Jahrzehnten wurden mit Hilfe der Niedertemperatur-Rastertunnelmikroskopie (STM) und der Rastertunnelspektroskopie (STS) die magnetischen und elektronischen Eigenschaften magnetischer Atome auf Metallsubstraten und Isolierschichten untersucht. In abhängig der zugrunde liegenden Substrate konnten sich die Wissenschaftler auf die sie jeweils interessierenden physikalisches Phänome konzentrieren. Wenn ein magnetisches Atom in direktem Kontakt mit einem metallischen Substrat steht, führt seine Wechselwirkung mit dem Bad der Leitungselektronen des Wirtsmetalls zu Vielteilchen-Quanteneffekten wie dem Kondo-Effekt. Es wurden mehrere Experimente durchgeführt, um die Entwicklung des Kondo-Effekts bei Veränderung der atomaren Umgebung eines lokalisierten Spins zu untersuchen. Trotz der herausragenden Ergebnisse dieser Experimente bleibt ein vollständig verstandenes Bild eine Herausforderung. Eine gängige Methode, um die Untersuchung von Adatomen auf Festkörpern zu vereinfachen, besteht darin, die Wechselwirkung des abgeschiedenen Atoms mit den Leitungsbandelektronen durch eine Isolierschicht zu reduzieren. Mit Entkopplungsschichten wie Cu2N, Al2O3 und MgO wurde das magnetische Verhalten von Fe-, Mnund Co-Adatomen untersucht. Eine großen magnetische Anisotropieenergie (MAE) für diese Systeme zu erhalten, war eine große Errungenschaft, um den Magnetismus auf kleinstem Niveau zu kontrollieren. Eine der herausfordernden Aufgaben im Magnetismus ist jedoch die Maximierung der MAE für Übergangsmetallsysteme. In dieser Arbeit wurde durch Nutzung der Möglichkeit, mit einem STM Versetzungen in Kristallen zu erzeugen, das schwierige und zeitaufwendige Verfahren zur Herstellung von Nanostrukturen durch Atommanipulation vermieden. Lange CuKetten bis zu 200 nm wurden hergestellt und verwendet, um den Kondo-Effekt von Co-Adatom zu untersuchen. Durch die Bindung des Co-Atoms an eine einatomige Cu-Kette änderte sich seine zuvor asymmetrische Kondo-Resonanz in eine spektrale Signatur, die in Bezug auf die Fermi-Energie symmetrisch ist. Weitere Untersuchungen der beobachteten symmetrischen Resonanz in Gegenwart eines externen Magnetfelds ergaben, dass diese eine inelastische Anregung darstellt. Durch Auswahl einer geeigneten atomaren Umgebung für Co-Adatome konnten wir das durch die Oberfläche reduzierte Orbitalmoment modifizieren, den Effekt der SpinOrbit-Wechselwirkung auf das Energiespektrum demonstrieren und eine messbare MAE erhalten. Darüber hinaus beobachteten wir bei den hergestellten Versetzungen auch Ketten und Gräben mit unterschiedlichen Breiten. Sie boten die Möglichkeit, die scheinbare Tunnelbarrierenhöhe (Φapp) in der Rastertunnelmikroskopie zu untersuchen. Die Variation der experimentellen Φapp für diese Nanostrukturen war theoretisch nicht erwartet. Ein kinetischer Energiebeitrag zum Tunnelprozess wird als Grund für den unerwarteten experimentellen Befund vorgeschlagen. Darüber hinaus wurde mittels Atommanipulation und STS die Rolle von Elektronen im Oberflächenzustand beim Kondo-Effekt von Co-Adatomen untersucht; ein Thema mit bisher widersprüchlichen experimentellen Beobachtungen. Unter Verwendung einer Stufenkante eines Kristalls zur Modulation der lokalen Zustandsdichte der Oberfläche beobachteten wir eine vernachlässigbare Variation der Breite der KondoResonanz. Dies zeigt eine untergeordnete Rolle der Elektronen im Oberflächenzustand an diesem Vielteilchenprozess

Parasitic worms of Acipenser stellatus, A. gueldenstaedtii, A. nudiventris and Huso huso (Chondrostei: Acipenseridae) from the southwest shores of the Caspian Sea

Sturgeons are the most important fish in the Caspian Sea, but there are only a few reports on their parasite communities in the southern part of this sea. In this study, a total of 93 individuals of four sturgeonspecies, namely Acipenser stellatus (n= 60), A.gueldenstaedtii (n = 12), A. nudiventris (n = 9) and Huso huso (n = 12), were caught in 2 geographical regions from the southwest of the Caspian Sea (Guilan Province,Iran) from March 2010 thtough May 2011. After recording biometric characteristics, standard necropsy and parasitological methods were used to identify parasites. Standard statistical computation (mean intensity,standard deviation, range, prevalence, abundance and dominance) were carried out for the overall samples and for samples grouped by season, geographical location, sex, length and weight. The differences between groups were determined by Kruskal Wallis test and Man Whitney U test (p< 0.05).Five worm species including 2 nematodes [Cucullanus sphaerocephalus and Eustrongylides excisus (L.)], 1 cestode (Bothrimonus fallax), 1 acanthocephalans (Leptorhynchoides plagicephalus) and 1 digenean trematode (Skrjabinopsolus semiarmatus) were found in A.stellatus, A. gueldenstaedtii, A. nudiventris and H. huso

Universal in vivo Textural Model for Human Skin based on Optical Coherence Tomograms

Currently, diagnosis of skin diseases is based primarily on visual pattern recognition skills and expertise of the physician observing the lesion. Even though dermatologists are trained to recognize patterns of morphology, it is still a subjective visual assessment. Tools for automated pattern recognition can provide objective information to support clinical decision-making. Noninvasive skin imaging techniques provide complementary information to the clinician. In recent years, optical coherence tomography has become a powerful skin imaging technique. According to specific functional needs, skin architecture varies across different parts of the body, as do the textural characteristics in OCT images. There is, therefore, a critical need to systematically analyze OCT images from different body sites, to identify their significant qualitative and quantitative differences. Sixty-three optical and textural features extracted from OCT images of healthy and diseased skin are analyzed and in conjunction with decision-theoretic approaches used to create computational models of the diseases. We demonstrate that these models provide objective information to the clinician to assist in the diagnosis of abnormalities of cutaneous microstructure, and hence, aid in the determination of treatment. Specifically, we demonstrate the performance of this methodology on differentiating basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) from healthy tissue

Ethyl benzene detection by BN nanotube: DFT studies

AbstractElectrical sensitivity of a boron nitride nanotube (BNNT) was examined toward ethyl benzene (C8H10) molecule by using density functional theory (DFT) calculations at the B3LYP/6-31G(d) level, and it was found that the adsorption energy (Ead) of ethyl benzene on the pristine nanotubes is about −11.42kJ/mol. But when nanotubes have been doped with Si, O, S. P atoms, the adsorption energy (Ead) and recovery time changed and the sensitivity of the nanotubes as adsorbent of C8H10 molecule was increased. Calculations showed that when the nanotube is doping, the adsorption energy will be equal to −1.75kJ/mol which leads to a decrease in the recovery time and also, due to doping the nanotube with O, the amount of HOMO/LUMO energy gap (Eg) will reduce significantly. It seems that nanotube (BNNT) is a suitable semiconductor after doping, and the doped BNNT in the presence of ethyl benzene an electrical signal is generating directly and therefore can potentially be used for ethyl benzene sensors, but BNNT is not a suitable adsorbent for C8H10 molecules

Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation

Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA) process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15 wt% and calcination temperatures of 673, 973, and 1073 K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active.Fil: Bordoloi, Ankur. Indian Institute of Petroleum; IndiaFil: Sanchez, Miguel Dario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Noei, Heshmat. Research Group X-Ray Physics and Nanoscience Deutsches Elektronen-Synchrotron; AlemaniaFil: Kaluza, Stefan. Fraunhofer Institute of Environmental, Safety, and Energy Technology; AlemaniaFil: Großmann, Dennis. Ruhr Universität Bochum; AlemaniaFil: Wang, Yuemin. Ruhr Universität Bochum; AlemaniaFil: Grünert, Wolfgang. Ruhr Universität Bochum; AlemaniaFil: Muhler, Martin. Ruhr Universität Bochum; Alemani

Parasitic worms and their histopathological effects in four sturgeon species from the southwest shores of the Caspian Sea

This study conducted to provide the status of parasite communities of four sturgeon species viz. Acipenser stellatus, A. gueldenstaedtii, A. nudiventris, and Huso huso in the southwest of the Caspian Sea and their histopathological effects on the examined fishes. For this purpose a total of 93 individuals of four sturgeon species were caught in two fisheries regions from the southwest of the Caspian Sea (Guilan Province, Iran) from March 2010 to May 2011. The histological slides of the infested tissues of the examined fishes were prepared for study of the histopathological effects of the parasites. Classical epidemiological variables, including mean intensity, prevalence, abundance and dominance were calculated for overall samples, grouped by season, geographical region, and sex. Five worm species, including two nematodes (Cucullanus   sphaerocephalus and Eustrongylides excisus larvae), one cestode (Bothrimonus fallax), one acanthocephalans (Leptorhynchoide plagicephalus) and one digenean trematode (Skrjabinopsolus   semiarmatus) were found in examined sturgeons and their histopathological effects on the fish tissues were assessed. Based on the results, the diversity of the parasites (including freshwater ones) in the southern part of the Caspian Sea have decreased since the time of the first study in 1972. This may be related to unfavorable conditions in freshwater ecosystems

Design, development and field assessment of a controlled seed metering unit to be used in grain drills for direct seeding of wheat

AbstractA new controlled seed metering unit was designed and mounted on a common grain drill for direct seeding of wheat (DSW). It comprised the following main parts: (a) a variable-rate controlled direct current motor (DCM) as seed metering shaft driver, (b) two digital encoders for sensing the rotational speed of supplemental ground wheel (SGW) and seed metering shaft and (c) a control box to handle and process the data of the unit. According to the considered closed-loop control system, the designed control box regularly checked the revolution per minute (RPM) of seed metering shaft, as operation feedback, using its digital encoder output. The seeding rate was determined based on the calculated error signal and output signal of the digital encoder of the SGW. A field with four different levels of wheat stubble coverage (10%, 30%, 40% and 50%) was selected for evaluation of the fabricated seed metering unit (FSMU). The dynamic tests were conducted to compare the performance of installed FSMU on the grain drill and equipped grain drill with common seed metering unit (CSMU) at three forward speeds of 4, 6 and 8 (Km/h) for DSW. Results of the FSMU assessment demonstrated that an increase in forward speed of grain drill (FSGD) and stubble coverage did not significantly affect the seeding rate in the grain drill for DSW. Using the FSMU reduced the coefficient of variation (CV) by approximately 50%. Consequently, applying the FSMU on the common grain drill led to a desirable seeding rate at different forward speeds of the grain drill and stubble existence

Ethyl benzene detection by BN nanotube: DFT studies

AbstractElectrical sensitivity of a boron nitride nanotube (BNNT) was examined toward ethyl benzene (C8H10) molecule by using density functional theory (DFT) calculations at the B3LYP/6-31G(d) level, and it was found that the adsorption energy (Ead) of ethyl benzene on the pristine nanotubes is about −11.42kJ/mol. But when nanotubes have been doped with Si, O, S. P atoms, the adsorption energy (Ead) and recovery time changed and the sensitivity of the nanotubes as adsorbent of C8H10 molecule was increased. Calculations showed that when the nanotube is doping, the adsorption energy will be equal to −1.75kJ/mol which leads to a decrease in the recovery time and also, due to doping the nanotube with O, the amount of HOMO/LUMO energy gap (Eg) will reduce significantly. It seems that nanotube (BNNT) is a suitable semiconductor after doping, and the doped BNNT in the presence of ethyl benzene an electrical signal is generating directly and therefore can potentially be used for ethyl benzene sensors, but BNNT is not a suitable adsorbent for C8H10 molecules

Evaluation of Trademarks Effect on Customers Loyalty Case Study: Software Industry

Undoubtedly , in today’s  markets , which are associated with increased competition , one way for company for more market share and achieve competitive advantage will be access to loyal customers. According to importance of this issue in business survival , especially in the field of software industry identifying factors that influence loyalty , the goal of this studies is investigating the important  factors that influence the customer loyalty . in order to achieve this goal, based on the conceptual model of relationship satisfaction value, resistance to change, sense of trust, and build brand equity and customer loyalty theory and we gathering our data with distribute 140 questionnaires between companies in Tehran that cooperate with one manufacturer company’s management information system software that for testing the data, we use spearman correlation coefficients were tested by structural equation analysis. Results indicate that brand equity and trust are the most important factor influencing patterns of behavioral and attitudinal loyalty. While the factors influencing behavioral loyalty versus attitudinal loyalty research in the field view may be different. Key words: trademarks, customer loyalty, industrial marketin