DRAIVERU PLATES AR TB6560AHQ MIKROSHĒMU, DARBĪBAS IZPĒTE

Scientific publications theme - Research of TB6560AHQ chip based stepper driver board.Work performers are Technology Academy of Rezekne, Faculty of Engineering, Second Level Professional Higher Education Bachelor's full-time study program "Mechatronics" fourth-year students Andris Pelšs, Elmārs Viļums. Scientific publications executive - Guntis Koļčs. Driver board TB6560 is designed for step motor control, it is designed for both businesses mass manufacturing of parts, as well as to private hobbies

Theoretical Aspects of Modern Qualitative Methods for Crisis Management

Scientists agree on necessity to predict and timely detect a company crisis that is an integral part of business nowadays. The early identification of a company financial failure due to rapidly changing social, economic and environmental conditions is a topic of growing importance. The sooner a potential financial failure can be identified, the more effective and efficient the anti-crisis measures could be implemented. If a company financial failure could be predicted accurately, it might be possible for the business to be restructured, thus avoiding the failure. This would benefit the owners, shareholders, employees, creditors, and others interested alike. The modern economic literature provides varied crisis diagnosis methods, mostly based on an analysis of key financial ratios. Less attention is paid to qualitative methods. Therefore, the present research aims to examine modern qualitative methods for company crisis diagnosis (prediction) in crisis management theory. The research used the theoretical findings of foreign scientists and Internet resources. The research employed the following methods: analysis and synthesis, induction and deduction, the monographic method, document analysis and the graphic method. The paper provides definitions of main terms related to company failure prediction and a description of general qualitative models of company financial failure (bankruptcy) prediction

SORPTION ROPERTIES OF LATVIAN CLAYS AND ENVIRONMENTAL PROTECTION SURVEY

The survey has been comprised in historical sequence. It has been attempted to group literature sources in a way that we consider to be the most relevant in the publication. Analysis of literature led to the following conclusions: during the last years most important and most advanced ways in investigations of Latvian clay surface characteristics have been found: Value determination of clay specific surface; Clay’s porous structure investigation; Cation exchange capacity determination; Characteristics of organoclays; Catalytic characteristics of Latvian clays; Practical usage of clays in waste water treatment; Usage of clays in adulterants elimination from vegetable oils; Clays as catalysts in of organic compound reactions; New type of sorbent from rapeseed oil treatment waste. Experimental measurements supplement data base about surface characteristics of Latvian clay samples

Utility of Asymmetric Amino Catalysis in Hench Synthesis

Darbā ir apkopota un analizēta literatūra par asimetriskajām organokatalītiskajām Mihaeļa reakcijām. Veikti kvantu ķīmiskie aprēķini imīnija un amināla katjoniem, kas satur halkona grupējumu. Veikta hirālu imidazolidinona un pirilidīna tipa organokatalizatoru sintēze. Optimizēta metode 1,4-DHP enantiomērās tīrības noteikšanai. Sintezēti halkoni ģeometriski tīrās formās, kā arī veiktas katalītiskās Hanča sintēzes reakcijasThe literature data on asymmetric organocatalytic Michael reactions have been collected and analysed. The quantum chemical calculations of chalcone moiety containing iminium and aminal ion geometry have been done. Chiral imidazolidinone on pyrolidine catalysts have been prepared. 1,4-DHP enantiomeric excess determination method has been optimized. Synthesis of chalcones in geometrically pure have been performed. Catalytic Hantzsch synthesis reactions have been carried out

Synthesis of 2,6-diazabicyclo[2.2.2]octane derivatives

2,6-Diazabiciklo[2.2.2]oktāna atvasinājumu sintēze. Pelšs J., zinātniskie vadītāji Dr. chem., vadošais pētnieks Žalubovskis R., Dr. chem., doc. Kļimenkovs I. Maģistra darbs, 51 lappuses, 7 attēli, 17 tabulas, 29 literatūras avoti, 1 pielikums. Latviešu valodā. Darbā ir veikta 2,6-diazabiciklo[2.2.2]oktān-3,5-ditionu sintēze reakcijā starp 2,6 diazabiciklo[2.2.2]oktān-3,5-dioniem un Lavesona reaģentu, kā arī iegūto biciklisko ditioamīdu alkilēšana, kuras rezultātā iegūti 3,5-bis(metiltio)-2,6-diazabiciklo[2.2.2]okta-2,5-diēni. Ir veikta arī 5-selēnokso-2,6-diazabiciklo[2.2.2]oktān-3-onu sintēze reakcijā ar Vūlinsa reaģentu. Literatūras apskatā ir apkopota informācija no pēdējo gadu publikācijām par tioimidātu un tioimīnija sāļu reducēšanas, alkilēšanas un aminēšanas reakcijām.Synthesis of 2,6-diazabicyclo[2.2.2]octane derivatives. Pelšs J., scientific supervisors Dr. chem., principal scientist Žalubovskis R., Dr. chem., doc. Kļimenkovs I. Master’s thesis, 51 pages, 7 figures, 17 tables, 29 literature references, 1 appendix. In Latvian. In this work, 2,6-diazabicyclo[2.2.2]octane-3,5-dithiones were synthesized in a reaction between 2,6-diazabicyclo[2.2.2]octane-3,5-diones and Lawesson’s reagent. The resulting bicyclic dithioamides were alkylated to yield 3,5-bis(methylthio)-2,6-diazabicyclo[2.2.2]octa-2,5-dienes. 5-Selenoxo-2,6-diazabicyclo[2.2.2]octane-3-ones were synthesized in a reaction between 2,6-diazabicyclo[2.2.2]octane-3,5-diones and Woolins’ reagent. The latest information on the reduction, alkylation and amination of thioimidates and thioiminium salts was collected in the literature review

Practical Methodologies for Amino Alcohol Based Natural Products Synthesis

Julkaistu vain painettuna, saatavuus katso Bibid. Published only in printed form, availability see BibidThe thesis deals with the methodology development for the purpose of practical synthesis of cyclic amino alcohol based natural products – amaminol and lepadin families by complying with the principles of ideal synthesis and especially step economy. In the first chapter a historical background of the conjugate reduction reaction is laid out and the development of currently one of the most selective conjugate reduction methods is described in detail. The method is based on the copper hydride chemistry employing triisopropyl phosphite as a ligand which is the key to the reduced reaction power and hence the high selectivity of the process. In the second chapter a comprehensive review of the decahydroquinoline based natural products synthesis – pumiliotoxin C and lepadin family is provided. More than forty total syntheses are categorized according to the strategy employed and analyzed in detail placing special emphasis on the construction steps. A proposal for cyclic amino alcohol natural products biosynthesis was also put forth. In the third chapter the design of two complementary approaches to lepadin alkaloids is provided dealing with both non-biogenetic and bio-inspired approaches. The studies performed resulted in the development of two new methodologies. First, the orthogonally protected amino epoxide was identified and its successful catalytic coupling with cyclic alkenyl copper reagent was discovered and developed into a scalable method. This chemistry provides the solution to two problems: the problematic reactivity of Boc-amino epoxides with organometallic reagents and the inability to orthogonally release the reactive benzylamino functionality of the products of dibenzyl-amino epoxide reaction with organometallic reagents. The second methodology – the unprecedented silica gel mediated spontaneous stereocontrolled allylic aminocyclization to form octahydroquinolines was discovered. This reaction is an example of the remote (1,4- from hydroxyl stereocenter, 1,5- from amino stereocenter) stereo induction. Such a reaction previously would only be possible to achieve using transition metal catalysis (Pd, Ir) and externally introduced chirality of the leaving group stereocenter (either by using chiral ligands or stoichiometric chiral reagents). The spontaneous nature and ease with which this reaction proceeds might also provide an implication on how lepadins are biosynthesized in the Nature

Synthesis of 2,6-diazabicyclo[2.2.2]octan-3,5-diones

2,6-Diazabiciklo[2.2.2]oktān-3,5-dionu sintēze. Pelšs J., zinātniskie vadītāji Dr. chem., vadošais pētnieks Žalubovskis R., Grandāne A., Dr. habil. chem. prof. Zicmanis A. Bakalaura darbs, 46 lappuses, 3 attēli, 18 tabulas, 28 literatūras avoti. Latviešu valodā. Darbā ir veikta 2,6-diazabiciklo[2.2.2]oktān-3,5-dionu sintēze trīskomponentu viena reaktora reakcijā. Tika sintezēta virkne 2,6-diazabiciklo[2.2.2]oktān-3,5-dionu ar dažādiem alkil- un arilaizvietotājiem pie bicikla C-1 un C-8 atomiem. Iegūto savienojumu struktūra tika pierādīta ar KMR spektroskopiju. 2,6-Diazabiciklo[2.2.2]oktān-3,5-diona reģioizomēra bicikliskā struktūra tika apstiprināta ar rentgenstruktūranalīzi. 2,6-DIAZABICIKLO[2.2.2]OKTĀN-3,5-DIONS, TRĪSKOMPONENTU REAKCIJA, AMĪDU IEKŠMOLEKULĀRĀ CIKLIZĀCIJA.Synthesis of 2,6-diazabicyclo[2.2.2]octane-3,5-diones. Pelšs J., scientific supervisors Dr. chem., principal scientist Žalubovskis R., Grandāne A., Dr. habil. chem. prof. Zicmanis A. Bachelor’s thesis, 46 pages, 3 figures, 18 tables, 28 literature references. In this work, 2,6-diazabicyclo[2.2.2]octane-3,5-diones were synthesized by a way of a three-component one-pot reaction. A series of 2,6-diazabicyclo[2.2.2]octane-3,5-diones with a variety of subtituents at the C-1 and C-8 atoms of the bicyclic structure. The structure of the synthesized compunds was confirmed by NMR spectra. The bicyclic structure of the regioisomer of 2,6-diazabicyclo[2.2.2]octane-3,5-dione was also confimed by X-ray structure analysis. 2,6-DIAZABICYCLO[2.2.2]OCTANE-3,5-DIONE, THREE-COMPONENT REACTION, INTRA-MOLECULAR CYCLIZATION OF AMIDES

Assessment of Biogas Station Impact on Material Productivity of Agricultural Complex

In search of alternatives for replacing fossil sources with renewable ones, intensive construction of biogas cogeneration power plants started in Latvia in 2008. Maize silage and manure are the most popular substrates used, yet, other alternatives are searched for and tested. It has to be assessed how the energy sector sustainability strategy can impact resource management in the agriculture sector. The aim of this paper is to determine how the introduction of the biogas station in typical agricultural complex consisting of farm and arable land has affected its material productivity. In this paper the biogas production impact on material flows and productivity were evaluated by applying material flow analysis to the case study object which is a traditional intensive farm in Latvia but now reoriented towards the production of electrical and thermal energy. The case study showed that introduction of the biogas station into the traditional farm caused materialization of this economic system, because eco-efficiency (economic output divided by material input) decreased by 41%. The main conclusion is that the biogas production from the biomass is favourable from energetic point of view but current renewable-energy policy in some cases can cause inefficient use of materials putting pressure on surrounding environmental systems and resource depletion

Team approach promotes households to save energy at home

The energy saving issues becomes more important in order to achieve the EU energy efficiency target by 2020. Within the household sector lies one of the greatest energy saving potential [1]. One of the main barriers for carrying out energy efficiency measures at households is the behavioral aspect [1;2]. Therefore it is important to find the best way to encourage households to change their energy behaviour and save energy at home