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The aim of this thesis is to study the metal-free activation of parahydrogen and the subsequent effects of parahydrogen-induced polarization (PHIP). PHIP is a nuclear spin hyperpolarization method that dramatically increases the sensitivity in NMR by enhancing signals in the spectrum. Typically, PHIP experiments involve catalysts based on metal complexes to activate parahydrogen. However, a recent discovery has shown that metal-free H2 activators can also lead to the spin hyperpolarization. At the same time, there were no reports about metal-free catalytic hydrogenations yielding in hyperpolarized products. The first part of the thesis focuses on metal-free hydrogenations of alkynes mediated by the ansa-aminoborane-based catalyst HCAT. In this research, we performed hydrogenations of various alkynes in a high magnetic field using parahydrogen. During these reactions, HCAT interacted with alkynes to form HCAT-alkyne adducts, which activated the parahydrogen molecules and resulted in the corresponding alkenes. Consequently, we observed enhanced signals of HCAT-alkyne-H2 intermediates, and most importantly, the alkene products. This represents the first example of PHIP effects on the hydrogenation products using a metal-free catalyst. Additionally, by applying PHIP, we studied and confirmed the proposed reaction mechanism. Next, we proceeded to further investigate metal-free hydrogenations utilizing parahydrogen. In the second paper, we examined hydrogenation of imines facilitated by the catalyst QCAT. These experiments resulted in enhanced signals in amine products. Additionally, we demonstrated the reversibility of a catalytic cycle, wherein the amines could interact with QCAT and parahydrogen, showcasing hyperpolarization of the NH group hydrogens. This study highlights the significance of PHIP experiments in providing valuable mechanistic insights into metal-free hydrogenations. Finally, we significantly expanded the range of biradicaloid-based metal-free

Ni–Zr0.82Y0.18O1.91 (YSZ) and Ni–La0.90Sr0.10ScO2.95 (LSS) cermets for solid oxide and protonic ceramic electrochemical cells were studied by means of H/D isotope exchange with the gas phase equilibration method for the first time. The experiments were carried out at 2 mbar of dry hydrogen in the temperature range of 400–800 ᵒC. The three parallel channels of hydrogen surface exchange were found to exist in both Ni-YSZ and Ni-LSS cermets. The mechanism of hydrogen isotope exchange for Ni-YSZ was found to be temperature independent, while, in the case of Ni-LSS, the mechanism changed with temperature and was more complicated at lower temperatures (400–600 °C). It was revealed that hydrogen spillover was the rate-determining step for both cermets. The electrochemical kinetics of hydrogen oxidation were studied on symmetric cells with a YSZ supported electrolyte and Ni-YSZ electrodes and with an LSS supported electrolyte and Ni-LSS electrodes in a wet (3 vol % H 2O) hydrogen atmosphere at 1 atm. The mechanism of hydrogen oxidation on the Ni-LSS electrode differs from that of the Ni-YSZ electrode. It changes with temperature and is also more complicated at a lower temperature range. © 2021 Elsevier B.V.

Parahydrogen-induced polarization is a nuclear spin hyperpolarization technique that can provide strongly enhanced NMR signals for catalytic hydrogenation reaction products and intermediates. Among other matters, this can be employed to study the mechanisms of the corresponding chemical transformations. Commonly, noble metal complexes are used for reactions with parahydrogen. Herein, we present a PHIP study of metal-free imine hydrogenations catalyzed by the ansa-aminoborane catalyst QCAT. We discuss the reaction mechanism by showing the pairwise nature of the initial hydrogen activation step that leads to the formation of the negative net nuclear spin polarization of N–H hydrogen in the QCAT-H₂ intermediate, enabling the further transfer of parahydrogen-originating protons to the imine substrate with the accumulation of hyperpolarized amine products. Parahydrogen-induced polarization also demonstrates the reversibility of the catalytic cycle.

We report nuclear spin hyperpolarization of various alkenes achieved in alkyne hydrogenations with parahydrogen over a metal-free hydroborane catalyst (HCAT). Being an intramolecular frustrated Lewis pair aminoborane, HCAT utilizes a non-pairwise mechanism of H₂ transfer to alkynes that normally prevents parahydrogen-induced polarization (PHIP) from being observed. Nevertheless, the specific spin dynamics in catalytic intermediates leads to the hyperpolarization of predominantly one hydrogen in alkene. PHIP enabled the detection of important HCAT-alkyne-H₂ intermediates through substantial ¹H, ¹¹B and ¹⁵N signal enhancement and allowed advanced characterization of the catalytic process.

Biradicaloids attract attention as a novel class of reagents that can activate small molecules such as H₂, ethylene and CO₂. Herein, we study activation of parahydrogen (nuclear spin‐0 isomer of H₂) by a number of 4‐ and 5‐membered pnictogen biradicaloids based on hetero‐cyclobutanediyl [X(μ‐NTer)₂Z] and hetero‐cyclopentanediyl [X(μ‐NTer)₂ZC(NDmp)] moieties (X,Z=P,As; Ter=2,6‐Mes₂−C₆H₃, Dmp=2,6‐Me₂−C₆H₃). The concerted mechanism of this reaction allowed observing strong nuclear spin hyperpolarization effects in ¹H and ³¹P NMR experiments. Signal enhancements from two to four orders of magnitude were detected at 9.4 T depending on the structure. It is demonstrated that 4‐membered biradicaloids activate H₂ reversibly, leading to SABRE (signal amplification by reversible exchange) hyperpolarization of biradicaloids themselves and their H₂ adducts. In contrast, the 5‐membered counterparts demonstrate rather irreversible parahydrogen activation resulting in hyperpolarized H₂ adducts only. Kinetic measurements provided parameters to support experimental observations.

The article describes the systems engineering processes, the current problems encountered in the work of a system engineer, the reasons for their occurrence and the goals, functionality of the new system tool “Product Studio”. «Product Studio» is Design Product Quality Assurance System and it aims to simplify the activities of the system engineer, providing the necessary functionality to perform the relevant processes from requirements definition and management, to the formation of architectural and technical solutions.

The present paper proposes a solution to the problem of improving the accuracy of cost estimation at the initiation stage of a project for the development of a software product, the main module of which is a knowledge-based mathematical module. The approach of used system modeling is described, aimed at simplifying the process of analyzing the complexity of the system and improving the accuracy of assessing labor costs. The result of the work is a validation of the proposed approach, performed on the comparison of the expert assessment, the obtained assessment after modeling the system, and actual labor costs. © Published under licence by IOP Publishing Ltd.

The article provides the information about a different role of the CRM-system as a method of enterprise management. Based on the theoretical data, there has been established methods for solving the problem of inefficient management and a number of ethical problems. What is more, there has been proposed recommendations to make the process of their solutions more «systemic»., В статье рассматривается роль CRM-системы как метода управления предприятием. На основе теоретических данных вырабатываются методы решения проблемы неэффективного управления, ряда этических проблем; предлагаются рекомендации, позволяющие сделать процесс их решения «системным».

Purpose. Due to establishment of Operational Control Centre on Belarusian railways the specifics of the work of traffic controller has changed, which led to the change of the principles of this job. The distinctive feature of the work of a traffic controller is the ability to perceive and process a considerable amount of information, quick decision-making, initiation of commands and verification of their fulfillment. The information burden on a train controller increases when there is an unscheduled change in a train table or in the event of abnormal situations. In other extreme situations a train controller has to perform several operations simultaneously, which requires to strain a visual sensory system and an acoustic analyzer, focus attention significantly and use short-term and long-term memory. To solve the optimization problem of the train controllers responsibilities it is reasonable to calculate the amount of information received and processed by the train controller depending on the nature of the operations during the work unit. This article aims to validate the methods that determine information load on the train controller depending on the actual situation on the section of the railway. The following factors are taken into consideration: an assessment of the occurrence of abnormal situations, the influence of operational and psychophysiological factors and limitations based on the application of simulation modeling. Methods. There are three main theories that evaluate the information received by a train controller, which study this information from different perspectives: statistical, semantic and structural. Statistical measure of information allows to link the probability of occurrence of each of the information messages and the amount of information in operator management. The semantic theory is used to calculate the amount of information circulating in the system of operator management and allows to take into consideration such a characteristic as, Цель. В связи с созданием Центра управления перевозками на Белорусской железной дороге изменилась специфика работы поездного диспетчера, которая привела к изменению характера диспетчерского труда. Особенностью труда поездного диспетчера является необходимость восприятия и переработки значительного объема информации, быстрой выработки решений, выдачи команд и проверки их выполнения. Значительно возрастают информационные нагрузки на поездного диспетчера при внеплановом изменении графика движения поездов, при возникновении нестандартных ситуаций. В остальных экстремальных ситуациях диспетчеру приходится выполнять одновременно несколько операций, что требует напряжения зрительного и слухового анализаторов, значительной концентрации внимания, использования оперативной и долговременной памяти. Для решения задачи оптимизации загрузки диспетчеров целесообразным является расчет количества информации, поступающей и перерабатываемой диспетчером в зависимости от характера выполняемых операций за рабочий период времени. Настоящая статья имеет целью обоснование методики определения информационной загрузки диспетчера в зависимости от реального положения на участке с учетом оценки возникновения нестандартных ситуаций, влияния эксплуатационных и психофизиологических факторов и ограничений на основе применения имитационного моделирования Методика. Для оценки информации, поступающей к поездному диспетчеру с точки зрения содержательного характера информации, приняты три основные теории, рассматривающие информацию с разных сторон: статистическая, семантическая и структурная. Статистическая мера информации позволяет связать вероятность появления каждого информационного сообщения и количество информации в операциях диспетчерского управления. Семантическая теория используется для расчета количества информации, циркулирующей в системе диспетчерского управления, и позволяет учесть такое свойство информационного обеспечения оперативного руководства эксплуатационной работой, как ценность предс, Мета. У зв'язку зі створенням Центру управління перевезеннями на Білоруській залізниці змінилася специфіка роботи поїзного диспетчера, яка привела до зміни характеру диспетчерського праці. Особливістю праці поїзного диспетчера є необхідність сприйняття і переробки значного обсягу інформації, швидкої вироблення рішень, видачі команд і перевірки їх виконання. Значно зростають інформаційні навантаження на поїзного диспетчера при позаплановому зміну графіка руху поїздів, при виникненні нестандартних ситуацій. В інших екстремальних ситуаціях диспетчеру доводиться виконувати одночасно кілька операцій, що вимагає напруги зорового і слухового аналізаторів, значної концентрації уваги, використання оперативної і довготривалої пам'яті. Для вирішення завдання оптимізації завантаження диспетчерів доцільним є розрахунок кількості інформації, що надходить і переробляється диспетчером в залежності від характеру виконуваних операцій за робочий період часу. Ця стаття має на меті обґрунтування методики визначення інформаційної завантаження диспетчера в залежності від реального стану на ділянці з урахуванням оцінки виникнення нестандартних ситуацій, впливу експлуатаційних і психофізіологічних факторів і обмежень на основі застосування імітаційного моделювання Методика. Для оцінки інформації, що надходить до поїзного диспетчера з точки зору змістовного характеру інформації, прийняті три основні теорії, які розглядають інформацію з різних сторін: статистична, семантична і структурна. Статистична міра інформації дозволяє зв'язати ймовірність появи кожного інформаційного повідомлення і кількість інформації в операціях диспетчерського управління. Семантична теорія використовується для розрахунку кількості інформації, що циркулює в системі диспетчерського управління, і дозволяє врахувати таку властивість інформаційного забезпечення оперативного керівництва експлуатаційною роботою, як цінність, що представляється. В системі диспетчерського управління за допомогою структурної заходи можна виз

Inefficient operation of distribution networks in transportation reduces the profits of commercial enterprises and increases the cost of goods for people. Using ineffective methods of ensuring cargo preservation leads to deteriorating consumer properties of goods, increased fuel consumption and an increase in the amount of harmful emissions from car exhaust gases. This enhances the negative impact of transport on the environment, especially in major cities, which makes the problem of ensuring cargo preservation and improving transport efficiency relevant. The objective of this work is to solve the problem of reducing the energy intensity of transportation and improving the efficiency of refrigerated vehicles in summer when delivering perishable goods (PGs) on urban routes. Factors that impact the energy intensity of PGs transportation by refrigerated vehicles are presented. When assessing the efficiency of refrigerated vehicles operation, it is proposed to take into account weather and transport operating conditions. An approach is formed to assessing the efficiency of refrigerated vehicles considering operating costs, cargo preservation costs, transportation energy intensity. © 2017 WIT Press.

Purpose. The main task of the higher school - training of competitive specialists who might possess deep the knowledge, choose important in information flow, know how to put into practice the theoretical knowledge and skills, provide right conclusions. In our time to train competent engineers important computer systems and information technologies are, system offer significant opportunities for storage, handling, delivery of any volume and content of the information. Education system face s not only the task of preparing a competent professional, but also a person aspiring to perfection, self-development, advance his professional level. Lifelong learning is at the same time while learning, the ability to apply this knowledge in practice. Th e main condition is the motivation, based on the needs and interests of the individual as a future engineer to achieve this goal. The task of the teacher of high school - to create a positive attitude to further development of the knowledge towards of the student, his interest in special subjects. This article is aimed at presentation of the methodology of teaching technical subjects in University transport using information technology. Methodology. The basis of learning is the formation individual orientation of personality, his values, formed the installation, the motives of activity and behavior. To Raise the professional abilities of the student, his creativity, means to, develop the ability to differentiate, analyze, compare, choose the best option for solving the various technical and life pro blems. The use of multimedia technology in the classroom contributes to a better and more efficient assimilation of the material. Creative of the personality can be formed with the students' independent work with literature, the latest developments with the use of the In ternet in various fields of science and technology. Selection of the reports for student confere, Аннотация. Цель Основная задача высшей школы – подготовка конкурентоспособных специалистов широкого профиля, которые могли бы владеть глубокими знаниями, выбирать в информационном потоке главное, уметь правильно применить на практике теоретические знания и навыки, делать правильные соответствующие выводы. В наше время для подготовки грамотных инженеров большое значение имеют компьютерные системы и информационные технологии, которые предоставляют значительные возможности в хранении, обработке, доставке любого объема и содержания информации. Перед системой образования стоит задача подготовки не только грамотного специалиста, но и личность, стремящуюся к совершенствованию, саморазвитию, повышению своего профессионального уровня. Непрерывное образование заключается одновременно в одновременном обучении, умении применить полученные знания на практике. Для достижения поставленной цели основным условием является мотивация, в основе которой лежат потребности и интересы личности как будущего инженера. Задача преподавателя вуза – создать позитивную установку на дальнейшее развитие знаний студента, заинтересовать его при преподавании специальных дисциплин. Настоящая статья имеет целью изложение методики преподавания технических дисциплин в транспортном вузе с использованием информационных технологий. Методика. Основой обучения является формирование направленности личности, ее ценностные ориентации, сформировавшиеся установки, мотивы деятельности и поведения. Повысить профессиональные способности студента, его творческий потенциал, т.е. развить способность дифференцировать, анализировать, сравнивать, выбирать наилучший вариант при решении различных технических и жизненных задач. Применение на занятиях мультимедийных технологий способствует более глубокому и качественному усвоению материала. Творческая направленность личности может формироваться при самостоятельной, Анотація. Мета. Основне завдання вищої школи - підготовка конкурентоздатних фахівців широкого профілю, які могли б володіти глибокими знаннями, вибирати в інформаційному потоці головне, уміти правильно застосувати теоретичні знання з практики і навички, робити правильні відповідні висновки. У наш час для підготовки грамотних інженерів велике значення мають комп'ютерні системи і інформаційні технології, які надають значні можливості у зберіганні, обробці, доставці будь-якого об'єму і змісту інформації. Перед системою освіти стоїть завдання підготовки не лише грамотного фахівця, але і особу, що прагне до вдосконалення, саморозвитку, підвищення свого професійного рівня. Безперервна освіта полягає одночасно в одночасному навчанні, умінні застосувати отримані знання з практики. Для досягнення поставленої мети основною умовою являється мотивація, в основі якої лежать потреби і інтереси особи як майбутнього інженера. Завдання викладача внз - створити позитивну установку на подальший розвиток знань студента, зацікавити його при викладанні спеціальних дисциплін. Ця стаття має на меті виклад методики викладання технічних дисциплін в транспортному внз з використанням інформаційних технологій. Методика. Спрямованості особи, її ціннісні орієнтації, установки, що сформувалися, мотиви діяльності і поведінки. Підвищити професійні здібності студента, його творчий потенціал, тобто розвинути здатність диференціювати, аналізувати, порівнювати, вибирати найкращий варіант при рішенні різних технічних і життєвих завдань. Застосування на зайнятті мультимедійних технологій сприяє глибшому і якіснішому засвоєнню матеріалу. Творча спрямованість особи може формуватися при самостійній роботі студента з літературою, новітніми досягненнями з використанням Інтернету в різних галузях науки, техніки. Вибір тим доповідей на студентські конференції вказує на інтереси осіб

Understanding how heterogeneous catalysts change size, shape and structure during chemical reactions is limited by the paucity of methods for studying catalytic ensembles in working state, that is, in operando conditions. Here by a correlated use of synchrotron X-ray absorption spectroscopy and scanning transmission electron microscopy in operando conditions, we quantitatively describe the complex structural dynamics of supported Pt catalysts exhibited during an exemplary catalytic reaction-ethylene hydrogenation. This work exploits a microfabricated catalytic reactor compatible with both probes. The results demonstrate dynamic transformations of the ensemble of Pt clusters that spans a broad size range throughout changing reaction conditions. This method is generalizable to quantitative operando studies of complex systems using a wide variety of X-ray and electron-based experimental probes., QC 20150720

We demonstrate that argon ion bombardment of single crystal sapphire leads to the creation of substrates that support the growth of vertically aligned carbon nanotubes from iron catalysts with a density, height, and quality equivalent to those grown on conventional, disordered alumina supports. We quantify the evolution of the catalyst using a range of surface characterization techniques and demonstrate the ability to engineer and pattern the catalyst support through control of ion beam bombardment parameters., Journal article published in Nano Letters, v14 p4997-5003, 2014.

We report a systematic and quantitative study of near-infrared intersubband absorption in strained AlGaN/GaN and lattice-matched AlInN/GaN superlattices grown by plasma-assisted molecular-beam epitaxy as a function of Si-doping profile with and without delta doping. For AlGaN/GaN, we obtained good theoretical agreement with experimental measurements of transition energy, integrated absorbance and linewidth by considering many-body effects, interface roughness, and calculations of the transition lifetime that include dephasing. For the AlInN/GaN system, experimental measurements of the integrated absorbance due to the superlattice transitions produced values more than one order of magnitude lower than AlGaN/GaN heterostructures at similar doping levels. Furthermore, observed transition energies were roughly 150 meV higher than expected. The weak absorption and high transition energies measured in these structures is attributed to columnar alloy inhomogeneity in the AlInN barriers observed in high-angle annular dark-field scanning transmission electron microscopy. We simulated the effect of these inhomogeneities using three-dimensional band-structure calculations. The inhomogeneities were modeled as AlInN nanorods with radially varying In composition embedded in the barrier material of the superlattice. We show that inclusion of the nanorods leads to the depletion of the quantum wells (QWs) due to localization of charge carriers in high-In-containing regions. The higher energy of the intersubband transitions was attributed to the relatively uniform regions of the QWs surrounded by high Al (95%) composition barriers. The calculated transition energy assuming Al0.95In0.05N barriers was in good agreement with experimental results.

We report a systematic and quantitative study of near-infrared intersubband absorption in strained AlGaN/GaN and lattice-matched AlInN/GaN superlattices grown by plasma-assisted molecular-beam epitaxy as a function of Si-doping profile with and without delta doping. For AlGaN/GaN, we obtained good theoretical agreement with experimental measurements of transition energy, integrated absorbance and linewidth by considering many-body effects, interface roughness, and calculations of the transition lifetime that include dephasing. For the AlInN/GaN system, experimental measurements of the integrated absorbance due to the superlattice transitions produced values more than one order of magnitude lower than AlGaN/GaN heterostructures at similar doping levels. Furthermore, observed transition energies were roughly 150 meV higher than expected. The weak absorption and high transition energies measured in these structures is attributed to columnar alloy inhomogeneity in the AlInN barriers observed in high-angle annular dark-field scanning transmission electron microscopy. We simulated the effect of these inhomogeneities using three-dimensional band-structure calculations. The inhomogeneities were modeled as AlInN nanorods with radially varying In composition embedded in the barrier material of the superlattice. We show that inclusion of the nanorods leads to the depletion of the quantum wells (QWs) due to localization of charge carriers in high-In-containing regions. The higher energy of the intersubband transitions was attributed to the relatively uniform regions of the QWs surrounded by high Al (95%) composition barriers. The calculated transition energy assuming Al0.95In0.05N barriers was in good agreement with experimental results.

We report a systematic and quantitative study of near-infrared intersubband absorption in strained AlGaN/GaN and lattice-matched AlInN/GaN superlattices grown by plasma-assisted molecular-beam epitaxy as a function of Si-doping profile with and without delta doping. For AlGaN/GaN, we obtained good theoretical agreement with experimental measurements of transition energy, integrated absorbance and linewidth by considering many-body effects, interface roughness, and calculations of the transition lifetime that include dephasing. For the AlInN/GaN system, experimental measurements of the integrated absorbance due to the superlattice transitions produced values more than one order of magnitude lower than AlGaN/GaN heterostructures at similar doping levels. Furthermore, observed transition energies were roughly 150 meV higher than expected. The weak absorption and high transition energies measured in these structures is attributed to columnar alloy inhomogeneity in the AlInN barriers observed in high-angle annular dark-field scanning transmission electron microscopy. We simulated the effect of these inhomogeneities using three-dimensional band-structure calculations. The inhomogeneities were modeled as AlInN nanorods with radially varying In composition embedded in the barrier material of the superlattice. We show that inclusion of the nanorods leads to the depletion of the quantum wells (QWs) due to localization of charge carriers in high-In-containing regions. The higher energy of the intersubband transitions was attributed to the relatively uniform regions of the QWs surrounded by high Al (95%) composition barriers. The calculated transition energy assuming Al0.95In0.05N barriers was in good agreement with experimental results.

We report a systematic and quantitative study of near-infrared intersubband absorption in strained AlGaN/GaN and lattice-matched AlInN/GaN superlattices grown by plasma-assisted molecular-beam epitaxy as a function of Si-doping profile with and without delta doping. For AlGaN/GaN, we obtained good theoretical agreement with experimental measurements of transition energy, integrated absorbance and linewidth by considering many-body effects, interface roughness, and calculations of the transition lifetime that include dephasing. For the AlInN/GaN system, experimental measurements of the integrated absorbance due to the superlattice transitions produced values more than one order of magnitude lower than AlGaN/GaN heterostructures at similar doping levels. Furthermore, observed transition energies were roughly 150 meV higher than expected. The weak absorption and high transition energies measured in these structures is attributed to columnar alloy inhomogeneity in the AlInN barriers observed in high-angle annular dark-field scanning transmission electron microscopy. We simulated the effect of these inhomogeneities using three-dimensional band-structure calculations. The inhomogeneities were modeled as AlInN nanorods with radially varying In composition embedded in the barrier material of the superlattice. We show that inclusion of the nanorods leads to the depletion of the quantum wells (QWs) due to localization of charge carriers in high-In-containing regions. The higher energy of the intersubband transitions was attributed to the relatively uniform regions of the QWs surrounded by high Al (95%) composition barriers. The calculated transition energy assuming Al0.95In0.05N barriers was in good agreement with experimental results.

Transmission Electron Microscopy (TEM) and optical measurements obtained from InN and InN-xGaxN films (0 < x < 0.54) grown by Molecular Beam Epitaxy are presented. Energy gaps measured by absorption, PR, and PL for InN films grown on c-plane Al2O3 were in the range of 0.7 eV. No In or other inclusions were observed in these films, ruling out the possibility of a strong Mie scattering mechanism. In the InN-xGaxN films the relationship between the structural properties and the optical properties, in particular the presence or absence of a Stokes shift between absorption and PL, is discussed. TEM studies show that high quality layers do not have a Stokes shift. Some films had compositional ordering; these films also showed a shift between absorption edge and luminescence peak., Sponsored in part by Department of Energy grant no. DE-AC03-76SF00098

A focused ion beam (FIB) is used to sequentially reduce the contact length of an evaporated metal film to a multiwalled carbon nanotube (MWCNT). By using this FIB contact cutback technique, the contact resistance between an individual MWCNT and evaporated thin films of Au, Au/Ti, and Ag are accurately determined. The data permit a rational way to specify the minimum contact length of a metallic thin film to a MWCNT. (c) 2008 American Institute of Physics.

Transmission Electron Microscopy and x-ray diffraction were used to study compositional modulation in InxGa1-x N layers grown with compositions close to the miscibility gap. The samples (0.34 < x < 0.8) were deposited by molecular beam epitaxy using either a 200-nm-thick AlN or GaN buffer layer grown on a sapphire substrate. In the TEM imaging mode this modulation is seen as black/white fringes which can be considered as self-assembled thin quantum wells. Periodic compositional modulation leads to extra electron diffraction spots and satellite reflections in x-ray diffraction in the theta-2(theta) coupled geometry. The modulation period was determined using both methods. Larger modulation periods were observed for layers with higher In content and for those having larger mismatch with the underlying AlN buffer layer. Compositional modulation was not observed for a sample with x = 0.34 grown on a GaN buffer layer. Modulated films tend to have large "Stokes shifts" between their absorption edge and photoluminescence peak., Sponsored in part by Department of Energy Contract no. DE-AC02-05CH1123.

A focused ion beam (FIB) is used to sequentially reduce the contact length of an evaporated metal film to a multiwalled carbon nanotube (MWCNT). By using this FIB contact cutback technique, the contact resistance between an individual MWCNT and evaporated thin films of Au, Au/Ti, and Ag are accurately determined. The data permit a rational way to specify the minimum contact length of a metallic thin film to a MWCNT. (c) 2008 American Institute of Physics.

Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiOx adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors.

Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiOx adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors.

Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiOx adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors.

Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiOx adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors.

© Inter-Research 2019. Rossia palpebrosa (Sepiolida) is the most abundant nekto-benthic cephalopod in the Arctic; however, its feeding and trophic ecology are largely unknown. This work aims to assess the role of this species in Arctic ecosystems based on the contents of its stomach and analyses of δ13C and δ15N stable isotopes in its beak. The main taxa identified in the food spectrum were Crustacea (frequency of occurrence: 52.1%), followed by Polychaeta (14.6%) and fishes (6.3%). Sipuncula and Echinoidea were occasionally found and were recorded here as R. palpebrosa prey for the first time, as well as Polychaeta and Euphausiacea. A significant geographic increase in δ13C values (mean ± SE, .19.3 ± 0.2‰) from the Barents Sea to West Greenland was found, but no significant ontogenetic increase, suggesting no migrations occurred among different water masses. Values of δ15N (8.7 ± 0.2‰) and trophic level (TL; 3.6 ± 0.1) revealed significant ontogenetic increases and an absence of geographic patterns, suggesting the trophic role of this species is similar throughout the studied part of the Arctic. Stable isotope values, TL and food spectrum for R. palpebrosa are close to Arctic nekto-benthic predatory fishes and shrimps, especially Pandalus borealis. However, sepiolids prey on organisms exceeding their own size and do not scavenge. A gradual ontogenetic decrease in isotopic niche width, while increasing diversity in the food spectrum of larger specimens, was observed in R. palpebrosa. However, δ13C values, i.e. variation in primary productivity supporting food sources, were more responsible for these ontogenetic differences in niche size than δ15N values.

© Inter-Research 2018. Gonatus fabricii is the most abundant cephalopod species in Arctic waters, and the only squid that completes its entire life cycle there. In order to understand its ecological role in the Arctic, we conducted stable isotope analyses of beaks from all ontogenetic groups from west and east Greenland waters and the Barents Sea, complemented with morphological data. The values of both δ13C and δ15N of G. fabricii were not related to sex. Values of δ13C showed a small ontoge-netic increase, and these values were geographically distinct, with highest levels found in the western part of the study area. Values of δ15N showed a dramatic ontogenetic increase (i.e. 10.0‰ δ15N; 2.6 trophic levels), from epipelagic juvenile forms to large bathypelagic adults, without significant geographical variation. The observed maximum value of δ15N (14.9‰) is the highest ever recorded in cephalopod beaks. The estimated trophic level (up to 5.1) compares only to top vertebrate predators in the Arctic: large piscivorous fishes, seals and toothed whales or large benthic scavenging fishes. Thus, G. fabricii is a top invertebrate predator in the Arctic, with the widest iso-topic niche observed to date for any species there. Among cephalopods its trophic level is only exceeded by its Antarctic congener, G. antarcticus, and by the Antarctic colossal squid Mesony-choteuthis hamiltoni. Thus, polar squids occupy higher trophic positions than do squids living in warmer regions. Finally, our study shows that G. fabricii descends to bathypelagic layers during ontogenesis, continuously increasing its trophic level by changing prey types and sizes, and avoiding predation pressure.

The strong line broadening observed in electron spin resonance on NaV2O5 is found to originate from an unusual type of the symmetric anisotropic exchange interaction with simultaneous spin-orbit coupling on both sites. The microscopically derived anisotropic exchange constant is almost 2 orders of magnitude larger than the one obtained from conventional estimations. Based on this result we systematically evaluate the anisotropy of the ESR linewidth in terms of the symmetric anisotropic exchange only, and we find microscopic evidence for precursor effects of the charge ordering already below 150 K. © 2006 The American Physical Society.

Quasi-one-dimensional (1D) spin systems are highly unconventional materials, which exhibit a wide variety of phenomena, including spin-Peierls transition and charge ordering. In this paper, we show that electron spin resonance (ESR) is a very powerful tool to study spin relaxation mechanisms in these systems. We review the microscopic theory of superexchange and include a discussion of some recent experimental and theoretical developments concerning ESR in 1D solids. Furthermore, we evaluate the anisotropy and the temperature dependence of the ESR linewidth in three 1D systems (LiCuVO4, CuGeO3, α'-NaV2O5). Thus, we can determine the type and the magnitude of the anisotropic exchange interactions between spins and investigate the effects of fluctuations of charge and lattice degrees of freedom in the vicinity of phase transitions in these systems. © 2008 Springer Science + Business Media B.V.

The strong line broadening observed in electron spin resonance on NaV2O5 is found to originate from an unusual type of the symmetric anisotropic exchange interaction with simultaneous spin-orbit coupling on both sites. The microscopically derived anisotropic exchange constant is almost 2 orders of magnitude larger than the one obtained from conventional estimations. Based on this result we systematically evaluate the anisotropy of the ESR linewidth in terms of the symmetric anisotropic exchange only, and we find microscopic evidence for precursor effects of the charge ordering already below 150 K. © 2006 The American Physical Society.

Quasi-one-dimensional (1D) spin systems are highly unconventional materials, which exhibit a wide variety of phenomena, including spin-Peierls transition and charge ordering. In this paper, we show that electron spin resonance (ESR) is a very powerful tool to study spin relaxation mechanisms in these systems. We review the microscopic theory of superexchange and include a discussion of some recent experimental and theoretical developments concerning ESR in 1D solids. Furthermore, we evaluate the anisotropy and the temperature dependence of the ESR linewidth in three 1D systems (LiCuVO4, CuGeO3, α'-NaV2O5). Thus, we can determine the type and the magnitude of the anisotropic exchange interactions between spins and investigate the effects of fluctuations of charge and lattice degrees of freedom in the vicinity of phase transitions in these systems. © 2008 Springer Science + Business Media B.V.

© 2019 The Author(s). The squid Gonatus fabricii (Lichtenstein, 1818) is the most abundant pelagic cephalopod in the Arctic and the only squid to spend all of its life cycle in this region. Despite being highly abundant, its reproductive biology remains poorly known, and data on large maturing and mature specimens are especially rare. This study, based on extensive material (51 large specimens and >35,000 specimens in all), fills major gaps in the knowledge of the reproductive biology and ecology of G. fabricii. The fecundity of females ranged from 8,862 to 16,200 oocytes, with mature and late maturing specimens having between 8,862 to c. 10,000 and 11,402 oocytes, respectively. Oogenesis was synchronous, and oocyte resorption was observed; resorbed oocytes constituted up to 23.5% of fecundity. Between two to five ripe oocytes were observed, and these were 4.0-5.5 mm in diameter (maximum dimension). Males possessed between 77 and 257 spermatophores (length = 5.8-10.8 mm). Spermatophores were characterized by a cement body with well-developed collar and discs at the oral end, an ejaculatory apparatus longer than the cement body and the lack of a tapered, sharp tip to the cement body. Spermatophore size showed a uniform increase in relation to increasing male size. In newer spermatophores, the length, width and volume of the seminal reservoir also increased. Females possessed between 62 and 84 spermatangia (length = 1.8-2.6 mm); the spermatangia were present on the buccal membranes and lacked special attachment structures. Seminal receptacles were not found on the buccal membranes of females. Our findings are consistent with the hypothesis of geographically restricted spawning in G. fabricii. The study found evidence for one new breeding area in south-eastern Greenland. No differences in sizes at maturity were found between the breeding areas. Such geographically localized reproduction is relatively common in non-deep-water squids, but is much less common in deep-wate

© 2018 Informa UK Limited, trading as Taylor & Francis Group. Cephalopods are an important, abundant and taxonomically diverse component of the bathypelagic realm. However, their biology, ecology and distribution are poorly known. Specimens of Mastigoteuthis agassizii (Mastigoteuthidae) have been captured in the southern part of the Denmark Strait, which is at approximately 65°N. This site is approximately 550 km north of the previously most northern known border of the Mastigoteuthidae range. The main goal of this paper is to provide an extended morphological description and biological analysis of M. agassizii, the first species of the Mastigoteuthidae caught in the Subarctic Atlantic. Despite sample collection at 534 deep-water stations in the area, only two specimens were captured, indicating the rarity of this species in the northern part of its range. We suggest that the typical range of this species is bathyal depths throughout the North Atlantic to the Subarctic, but not through the Denmark and Davis Straits to the Arctic. These findings coincide with the geographic border of the Northern Atlantic boreal bathyal province, which is warmer and more saline compared to the Arctic province further to the north. We also provide the first descriptions of the radula and reproductive system of M. agassizii. The female had synchronous ovulation, fecundity of approximately 23,000 oocytes, oocyte resorption having not been found, most likely due to the early maturity stage of the female. The males, as proven by our sample and additional photo in other source, were found to have the distal part of the penis enlarged, divided into two valves and pigmented, possibly indicating they can protrude outside the mantle cavity. This enlarged valved part, as it is supposed in the literature for other deep-water squid families having it, may be used as an analogue to the lacking hectocotylus.

The spin dynamics of the prototypical quasi-one-dimensional antiferromagnetic Heisenberg spin S=1/2 chain KCuF3 is investigated by electron spin resonance spectroscopy. Our analysis shows that the peculiarities of the spin dynamics require a new dynamical form of the antisymmetric anisotropic spin-spin interaction. This dynamical Dzyaloshinsky-Moriya interaction is related to strong oscillations of the bridging fluorine ions perpendicular to the crystallographic c axis. This new mechanism allows us to resolve consistently the controversies in observation of the magnetic and structural properties of this orbitally ordered perovskite compound. © 2008 The American Physical Society.

We present detailed electron spin resonance investigations on single crystals of the low-dimensional quantum magnet TiOCl. The anisotropy of the g factor indicates a stable orbital configuration below room temperature and allows us to estimate the energy of the first excited state as 0.3 (1) eV, ruling out a possible degeneracy of the orbital ground state. Moreover, we discuss the possible spin relaxation mechanisms in TiOCl and analyze the angular and temperature dependence of the linewidth up to 250 K in terms of anisotropic exchange interactions. Towards higher temperatures an exponential increase of the linewidth is observed, indicating an additional relaxation mechanism. © 2006 The American Physical Society.