29 research outputs found
Energy level alignment and site-selective adsorption of large organic molecules on noble metal surfaces
No full textIn recent two decades, there has been a large interest in organic molecules on metallic as
well as insulating substrates. This interest is caused by the need to understand fundamental
properties of large organic molecules on solid surfaces at the level that properties
of smaller adsorbates, like carbon monoxide or oxygen molecule, are understood. In addition,
theoretical and experimental studies in this field are driven by potential applications
of organic materials as active components in light-emitting diodes (OLEDs) and fieldeffect transistors (FETs), as well as by on-going efforts to use single molecules as building
blocks in nano-electronic and nano-mechanical devices.
This Thesis deals with two aspects of large organic molecules on metal surfaces: local
adsorption geometry and energy level alignment. Molecules bind to specific sites on
metallic surfaces which correspond to the lowest total energy of the molecule-substrate
system. It is of fundamental interest to understand the electronic causes of the interaction
between the molecule and the surface. Ultimately, one would like to gain understanding
of what causes molecule-substrate attraction and why this attraction is stronger for some
particular geometries than for others. Another important aspect is the alignment of
molecular levels with respect to the Fermi level of the metal. This level alignment governs
the electron injection from the metal to the molecule (or vice versa) in electronic devices.
At the beginning of the Thesis, we review our main theoretical tool, density functional
theory (DFT), and present details of the plane-wave implementation of DFT. We
introduce concepts which are useful in analyzing surface science systems, such as surface
energy, work function, electron density difference, difference in density of states, etc. We
present calculations of copper and silver bulk and surfaces to assess how density functional
theory performs for noble metals. We then investigate a specific surface science
system to demonstrate these concepts, namely, chlorine adsorbed on the Ag(111) surface
at submonolayer coverages. We find that the adsorption energy of Cl on Ag(111) is about
2.9 eV and depends only weakly on coverage. The Ag-Cl bond is very strong and can
be best described as ionic. Adsorption of Cl on the Ag(111) surface leads to electron
charge transfer from the metal to the adsorbate. Each chlorine atom acquires about 0:2
additional electrons upon adsorption. Because of this charge transfer the work function
of adsorbate-covered substrate increases. We find a very good agreement between theory
and available experimental data. Small dependence of adsorption energy on coverage can
be explained by lateral repulsion of adsorption-induced dipoles.
Chapter 4 of the Thesis is devoted to site-selective adsorption of one specific molecule,
1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA), on the Ag(110) surface. We
perform large-scale density functional calculations of several local adsorption sites and
analyze the results in great detail. Calculations reveal that NTCDA prefers adsorption
geometry in which the peripheral oxygen atoms lie directly above the silver atoms in the
[1�10] atomic rows. This nicely agrees with available experimental data. From the analysis
of DFT calculations we are able to understand why this happens. Firstly, NTCDA is a
molecule with electron accepting properties. In the gas-phase molecule the oxygens of
the side groups are negatively charged while the central naphthalene core is positively
charged. When the molecule is adsorbed on the Ag(110) surface, about 0:4 electrons are
transfered to the lowest occupied molecular orbital (LUMO). Silver atoms in the topmost
atomic layer become positively charged and this causes electrostatic attraction between
negatively charged oxygen atoms of NTCDA and positively charged silver atoms. This
attraction is maximum when oxygens are just above the silver atoms in the [1�10] atomic
rows. Thus, on the basis of DFT calculations, we have developed a model for site-selective
adsorption of NTCDA on the Ag(110) surface. This model should also be applicable in
case of adsorption of a related molecule, PTCDA, on the same surface.
In Chapter 5 we analyze the energy level alignment of copper octaethylporphyrin
(CuOEP) on three metal surfaces: Ag(001), Ag(111) and Cu(111). The experiments that
this analysis is based on were performed in the Institute of Physics of University of Basel,
in the NanoLab group. We first critically review and discuss different physical mechanisms
that lead to a formation of the interface dipole at metal-organic interfaces. These different
mechanisms are: charge transfer (as described by the so-called induced density of interface
states (IDIS) model), polarization of the adsorbate near the metal surface, push-back
effect, which is a consequence of the Pauli exclusion principle, permanent electrostatic
dipoles at interfaces, and charge transfer caused by chemical interactions. Then we discuss
in detail experimental results and evaluate the contribution of each mechanism to the
total interface dipole. We conclude that the push-back effect is the most important for
CuOEP/metal interfaces
Impact of Heat Exchanger Effectiveness and EGR on Energy and Emission Performance of a CI Engine
No full textThis study explores the impact of intake air cooling intensity, defined by heat exchanger effectiveness (HEE) and exhaust gas recirculation (EGR), on the energy and environmental performance of a turbocharged compression ignition (CI) engine. Experimental investigations were conducted on a 1.9-litre CI engine operating at 2000 rpm under three brake mean effective pressure (BMEP) conditions (0.2, 0.4, and 0.6 MPa), which correspond to part-load engine operation. HEE was varied at 0%, 50%, and 100%, in both EGR-on and EGR-off modes. Additional numerical simulations were carried out using AVL BOOST software to analyze combustion dynamics, including engine operating cycle modeling to validate the accuracy of the combustion analysis. The results demonstrate that increasing HEE significantly improves cylinder filling and excess air ratio, leading to enhanced combustion efficiency and lower in-cylinder temperatures. This, in turn, reduces specific NOx emissions by approximately 40% with EGR and approximately 60% without EGR; however, under EGR-on conditions, the reduced combustion intensity leads to increased smoke and unburned hydrocarbon emissions—particularly at high cooling intensities. This effect is primarily associated with the engine control unit’s (ECU) limitations on intake air mass flow to maintain the target EGR ratio. Integrated control of HEE and EGR systems improves engine performance and reduces emissions across varying conditions, while highlighting trade-offs that inform the refinement of air management strategies
О специфике развития человеческого потенциала: метаквалификация как фактор адаптации к политическим, экономическим и социальным изменениям
No full textIn this article the challenges which society face in the XXI century are analyzed. The author describes such processes of adaptation occurring in societies as shifting of priorities in the educational process, appearance of the new approaches to professional qualification, and the perception changes of the role of human intelligence.В данной статье рассматривается особенность вызовов, с которыми сталкивается общество в XXI в. Автор описывает происходящие в обществе процессы адаптации в виде смещения приоритетов в образовательном процессе, новых подходах к профессиональной квалификации, а так же в изменении восприятии роли человеческого интеллекта
Woods inhabitants Geruliai and the Lithuanians’ descent history from the Romans
No full textNuo 1960 m. rinkdamas duomenis iš istorijos šaltinių, autorių darbų, istorijos žemėlapių, vietovardžių bei etnonimų paminėjimų, autorius sukaupė nemažą archyvą lietuvių kilmės klausimais. Straipsnyje aprašomi baltų ir jiems giminingų tautų karai ir klajonės vėlyvaisiais antikos laikais ir ankstyviausio baltų susidūrimo su krikščionybe metu.Since 1960 the author of the article has been collecting data from historical sources, works by other researchers, historical maps, the mentions of toponyms and ethnonyms; as a result, he accumulated a rather exten-sive archive on the issue of the Lithuanians’ descent. The article presents the wars and the nomadic lifestyle of the Baltic and other akin tribes in the period of late antiquity and the early period of confrontations between the Balts and Christianity
On Specifics of Human Development: Metaqualification As a Factor of Adaptation to Political, Economic and Social Changes
No full textIn this article the challenges which society face in the XXI century are analyzed. The author describes such processes of adaptation occurring in societies as shifting of priorities in the educational process, appearance of the new approaches to professional qualification, and the perception changes of the role of human intelligence
Spark Ignition (SI) Engine Energy and Ecological Performance Using Natural Gas and Late Intake Valve Close (LIVC)
No full textNatural gas stands out as a promising alternative fuel, and utilizing late intake valve close (LIVC) can further enhance its potential by improving internal combustion engine performance. The present study investigated the effect of LIVC on the performance of a Nissan Qashqai J10 four-cylinder internal combustion ignition engine (ICE) operating on gasoline (G) and natural gas (NG), with a focus on both energy and ecological aspects at stoichiometric points. Experimental tests were performed under the usual engine operating conditions, with engine speeds of 2000 and 3000 rpm and brake mean effective pressures (BMEPs) of 0.31, 0.55, and 0.79 MPa, while the intake valve closing moment was delayed at 24°, 31°, 38°, 45°, 52°, and 59° after bottom dead center (aBDC). The software AVL BOOST™ (version R2021.2) and its utility BURN were used to calculate the rate of heat release (ROHR), mass fraction burned (MFB), in-cylinder temperature, and the rate of temperature rise. The substitution of natural gas for gasoline substantially decreases CO2 and NOx emissions while enhancing the engine’s energy efficiency. Implementing a LIVC strategy can further boost brake thermal efficiency and reduce CO2, though it negatively impacts CO, HC, and NOx emissions. Optimal performance necessitates balancing efficiency improvements and CO2 reduction against the control of other pollutants, potentially through combining LIVC with alternative engine control methodologies
Seizure of the ship
No full textMaģistra darbs veltīts kuģa apķīlāšanas institūta izpētei. Maģistra darba mērķis ir izprast kuģu un peldošo konstrukciju jēdzienus, atšķirības, apķīlāšanas un arestēšanas institūtu piemērošanas gadījumus, identificēt aktuālās problēmas normatīvajā regulējumā un izstrādāt priekšlikumus, kā kuģu un peldošo konstrukciju apķīlāšanas procesu padarīt efektīvāku. Lai sasniegtu maģistra darba mērķi, autors ir aplūkojis Latvijas un ārvalstu normatīvos aktus, juridisko literatūru, publikācijas, kā arī Latvijas tiesu praksi. Maģistra darba pētījuma rezultātā izstrādāti secinājumi un priekšlikumi sprieduma izpildes institūta uzlabošanai, kā arī Civilprocesa likuma grozījumiem.Master's thesis is devoted to the ship seizure institute. The aim of the master's thesis is to understand the concept of ships and floating structures, their differences, cases of seizure and arrest institute application, as well as to identify problems in the current regulatory framework and to develop proposals in order to make the process of seizing ships and floating structures more efficient. In order to achieve the aim of the master's thesis, the author has reviewed Latvian and foreign normative acts, legal literature, publications, as well as Latvian case law. As a result of the master's thesis, conclusions and suggestions for the improvement of the Judicial Enforcement Institute, as well as amendments to the Civil Procedure Law have been developed
Recovery against salary and payments assimilated to it.
No full textBakalaura darbs veltīts piedziņas vēršanas uz darba samaksu un tai pielīdzināmiem maksājumiem izvērtēšanai. Bakalaura darba mērķis ir pētīt piedziņas būtību, piedziņas vēršanas uz mantu vispārīgo kārtību, piedziņas vēršanas uz personas naudas līdzekļiem īpatnības, kā arī piedziņas vēršanu pret nepilngadīgas personas darba samaksu un citiem naudas līdzekļiem. Lai sasniegtu bakalaura darba mērķi, autors ir aplūkojis Latvijas un ārvalstu normatīvos aktus, juridisko literatūru, publikācijas, kā arī Latvijas tiesu praksi. Bakalaura darba pētījuma rezultātā izstrādāti secinājumi un priekšlikumi sprieduma izpildes institūta uzlabošanai, kā arī Civilprocesa likuma un Darba likuma grozījumiem. Atslēgvārdi: Civilprocesa likums, civilprocess, piedziņa, piedziņa uz darba samaksu, sprieduma izpilde, piedziņas ierobežojumi.This Bachelor's thesis is dedicated to the assessment of levy execution of wages, salaries and similar payments. The purpose of this Bachelor's thesis is to study the essence of levy, the general procedure for levy execution of property, the characteristics of levy execution of funds, as well as levy execution of minors’ wages, salaries and other funds. In order to achieve the aim of this Bachelor's thesis, the author has reviewed Latvian and foreign law, legal literature, publications, as well as Latvian case law. As a result of the study of this Bachelor's thesis, conclusions and suggestions for improving the institute of enforcement of the judgment, as well as amendments to the Civil Procedure Law and Labor Law have been developed. Keywords: Civil Procedure Law, Civil Procedure, Levy, Levy Execution of Wages and Salaries, Judgement Enforcement, Levy Restrictions
Attitudes, perceptions, and guidance practices of Illinois guidance directors concerning vocational education in secondary schools
No full textPurpose. The primary purpose of this study was to determine the attitudes, perceptions, and guidance practices of guidance directors concerning vocational education in comprehensive secondary schools in Illinois. A secondary purpose of this study was to investigate the relationships among the attitudes, perceptions, and counseling practices of guidance counselors concerning vocational education and selected demographic variables.Methodology. The target and accessible populations were all guidance directors in comprehensive secondary schools in Illinois. Proportionate stratified random sampling was used to determine the actual sample of 253 guidance directors, with size of high school enrollment as the stratifying variable. A pilot study revealed that the questionnaire, developed by the researcher, possessed validity and reliability. Questionnaires were mailed to subjects in April, 1988. Reminder postcards and follow-up questionnaires were also mailed. Statistical procedures used to address this study's research questions were: frequency distributions, percentages, means, standard deviations, t-tests, analysis of variance, correlations, and multiple regression. Since no significant differences between respondents and non-respondents were observed, the results obtained from the respondents were generalized to the entire sample and the target population.Findings and conclusions. (1) Guidance directors had generally positive attitudes toward vocational education in comprehensive secondary schools (3.63 on the 5-point scale). (2) Guidance directors were generally uncertain concerning their perceptions of vocational education in their schools (3.30). (3) The overall program quality mean was higher for business education (3.98) compared to agricultural education (3.49), home economics (3.44), and industrial education (3.41). (4) Departmental guidance practices concerning vocational education were perceived to be generally positive (3.74) by guidance directors. (5) Significant, positive relationships were observed between guidance directors' attitudes toward vocational education and departmental guidance practices (r =.60) and between their perceptions of vocational education in their schools and departmental guidance practices (r =.42).Made available in DSpace on 2011-05-07T14:01:47Z (GMT). No. of bitstreams: 2
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The development of low-fat/low-salt frankfurters
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Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionCommercially available frankfurters (N = 25) were evaluated in order to identify a range of sensory properties that were considered to be acceptable to consumers. Hardness, cohesiveness, saltiness, flavor intensity and off-flavor intensity values that were within one standard deviation of the mean were identified as acceptable values.Three central composite designs (N = 17 treatment combinations--salt, fat and pH--or N = 12 treatment combinations--salt, fat and soy protein or carrageenan)--were used to determine the effects of fat, salt, pH, soy protein and carrageenan on sensory properties of frankfurters. Response surface techniques were used to identify a range of variable levels that could produce acceptable frankfurters. Desirable processing and flavor profile characteristics were achieved at pH 6.0. As salt levels increased, hardness, juiciness, saltiness and flavor intensity scores increased. As fat content increased, juiciness scores decreased due to the substitution of water for fat in the formulation. Increased fat content resulted in decreased off-flavor scores. Model predictions suggest that acceptable frankfurters can be manufactured with a minimum of 11.25% fat and 1.3% salt at pH 6.0.The addition of soy protein to frankfurters increased hardness and off-flavor intensity and decreased juiciness, saltiness and flavor intensity scores. The addition of carrageenan to frankfurter formulations increased hardness scores at levels below 1.7% salt and decreased juiciness scores at levels above 15% fat. Saltiness, flavor intensity and off-flavor intensity scores increased with increasing levels of carrageenan.The effects of different cooking methods (steep, microwave and broil) and final cooking temperatures (66\sp\circC, 77\sp\circC and 88\sp\circC) on the physical and sensory properties of frankfurters were evaluated using 3 x 3 factorial design. Instron hardness, shear force, sensory hardness and saltiness scores increased and juiciness scores decreased with increased temperature when frankfurters were cooked by either microwaving or broiling. These effects were associated with evaporative moisture loss. Frankfurter density decreased with increased ultimate temperature and was attributed to increased volume of gas. Expressible moisture increased with increased ultimate temperature when frankfurters were steeped. Neither cooking procedures or ultimate temperature influenced protein denaturation as determined by gel electrophoresis or enzymatic digestion.U of I Onl
