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Uniaxial Tension of Wedge-Type Anchorage System
No full textAim of the research is designing of a potted-type anchor for high-strength composite rod failed in the gauge zone
Dzelzs oksīda magnētisko nanodaļiņu sintēze, īpašības un pielietošanas iespējas
No full textPateicoties unikālām īpašībām, labai
biosaderībai un zemiem toksikoloģiskiem rādītājiem, dzelzs
oksīda magnētiskās nanodaļiņas ir perspektīvs pētījumu objekts.
Magnētisko nanodaļiņu sintēzei izmantoja sola-gēla metodi un
nogulsnēšanu no šķidras fāzes. Lai kontrolētu reakcijas kinētiku,
kas ir cieši saistīta ar dzelzs jonu oksidācijas ātrumu, magnetīta
daļiņu sintēze jāveic bezskābekļa vidē, piemēram, barbotējot
argona gāzi. Izstrādāti sastāvi α-Fe2O3, γ-Fe2O3 un Fe3O4 sintēzei,
ko apliecina rentgenstaru difrakcijas analīzes pētījumu rezultāti
Tiocianāta un cilvēka ogļskābes anhidrāzes II mijiedarbības kvantu ķīmisks pētījums
No full textLai noskaidrotu tiocianāta un CA II mijiedarbības mehānismu, veikta detalizēta kvantu ķīmiskā
izpēte, izmantojot pusempīrisko PM6 metodi. Aktīvā centra modelis tika balstīts uz CA II struktūras kristalogrāfiskajiem datiem (PBP kods - 2CBA). Modelī tika iekļauti: Zn2+ katjons,kas ir saistīts ar OH- ligandu un triju histidīnu – His94, His96, His119 – atlikumu imidazolu gredzeniem; atlikumi Glu106, Thr199, Thr200, His107, Arg246, Asn244, Gln92 un 8 ūdens molekulas. Mijiedarbības pirmā stadija noris spontāni un tās gaitā notiek tiocianāta molekulas deprotonēšana un tiocianāta
anjona (SCN-) veidošanās. Pēc ts pārvarēšanas cinka koordinācijas sferā noris ūdens molekulas aizvietošana ar tiocianāta anjonu SCN-. Līdzsvara stāvoklī saites Zn-N garums ir 1,844 Å, un atbilstošā saites kārta ir 0,639
Application of Triazolyl Purine Derivatives in Nucleophilic Aromatic Substitution Reactions
No full textThe synthesis and applications of novel bis-triazolyl purine derivatives are described
Augstas izturības betona mikrostruktūras, mehānisko īpašību un ķīmiskās izturības likumsakarības
No full textRakstā apkopota informācija par augstas izturības betonu, tā īpašībām un izmantotām izejvielām, pamata un speciālām ķīmiskām piedevām. Apskatīti betona korozijas iemesli un notiekošie procesi. Eksperimentālajā daļā pētīti betona paraugi ar dažādu superplastifikatora daudzumu. Noteikta betona paraugu ūdens un sulfāta sāļu šķīdumu uzsūce, mineraloģiskais sastāvs, mehāniskās īpašības atkarībā no pieliktā superplastifikatora daudzuma. Pēc eksponēšanas sulfātu sāļu šķīdumos betona paraugiem veikta vizuālā novērtēšana, šķīduma pH, svara izmaiņu, mineraloģiskā sastāva izmaiņas izvērtēšana, porozitātes un spiedes stiprības noteikšana
The Synthesis and Properties of Aza- and Oxy- Containing Phthalodinitrile Compounds
No full textThe syntheses of phthalodinitriles containing oxyalkylpyridine or cyclic amine substituents are reported. The phthalodinitriles were prepared from 4-nitrophthalodinitrile in reaction with 3- or 4-piperidinecarboxylic acid ethyl esters, 3- or 4-pyridylmethanol, 3- or 4-pyridylpropanol, 4-piperidinecarboxylic acid in aprotic solvents: N,N-dimethylformamide (DMF) and N-methylpyrrolidone. Influence of nucleophile properties on substitution of nitro group in 4-
nitrophthalodinitrile molecule was investigated. Appointed, that 4-nitrophthalodinitrile nitro group was easy replaced with all nucleophiles. Microwave and ultrasonic effects were studied.
Found, that both microwave and ultrasonic effects promoted the reaction speed, but did not influence on products yield and composition. The molecular structures of new compounds were
characterized by IR, 1H-NMR and mass-spectral data. Obtained products yields were from 18 till 83%
Quenching of Partial Discharges in Medium Voltage Networks by Traditional Arc Suppression Coil
No full textIn this article, we describe a possibility
to quench Partial Discharges (PD) in medium
voltage networks by using Residual Current
Compensation (RCC) device (Swedish Neutral),
proposed by K. Winter. If voltage network phase
PD activity increases in one of medium, the RCC
device shifts network neutral potential in such a way,
that voltage of spoiled phase to earth decreases
below PD extinction level. The expensive RCC device
is necessary.
There is a cheaper way for this purpose to use
traditional arc suppression coil with auxiliary power
winding. In case of increasing PD activity it is
possible to inject in coil auxiliary winding a proper
voltage, which diminishes the network spoiled phase
voltage and decreases PD activity.
The main aim of this article is to show the
possibility to use arc suppression coils auxiliary power
winding for quench of PD in medium voltage networks
and to substitute a more expensive RCC device
The Influence of Real Estate Market Cycle on the Development in Latvia
No full textIn the current study the free vibrations of stepped anisotropic rectangular plates on elastic foundation are considered. In this scientific article there are considered the main problems of real estate market cycle, the main interrelated economic aspects of the problem and their connection with real estate development. The research objective is to identify the main regularities of the influence of real estate market cycle on the development in Latvia, having paid special attention to economic aspects of the problem. In the research there have been used comparative, historical, statistical methods and the method of enumeration. On the basis of the conducted research the authors have provided recommendations for decreasing risks of development and unbalanced market cycle that will facilitate more effective decision-making promoting stable long-term development of the economy as a whole
The Concept of the Latvian Industrial Property Market Development Model in a Context of the Strategic Planning
No full textThe purpose of the Article is to introduce the worked out model on the Latvian industrial real estate market development forecasting for the professional auditorium. The originality/value of the Paper is that the proposed model anticipates the high quality (A class) industrial property stock and the manufacturing branch potential capacity applying the projections of the European climate change data. The research is supplemented with the results from the industrial regional specialization analysis recently made for the Baltics. The main findings are that the model predicts the manufacturing value added dynamics planned in the Latvian National Development Programme until 2020 conforming the impetuous development scenario that is too ambitious at the current industrial market development stage of an extremely low regional specialisation level in Latvia. Although the weighted average scenario’s projected manufacturing capacity of 1.01 compound average annual growth rate corresponds to 1.72 times larger A class industrial property stock in 2020 in Latvia that expects the sufficient capital inflows and increase of the multinational enterprises business activity. The use of the ENSEMBLES project’s complex data results, logical approach and comparisons, the system and dynamic row's analyses, calculations of the Gini coefficient on regional specialization supported by the empirical evidence on the scientific and business literature review is a complex of the methods applied in the research
UML Sequence Diagram: Transformation from the Two-Hemisphere Model and Layout
No full textModeling of the object interaction is one of the core
tasks during system analysis and design, because it gives
developer an ability to define responsibilities of class objects and
to sketch general architecture of software components. In this
task an ability of automatic generation of the UML sequence
diagram becomes one of the most important activities. The twohemisphere
model contains enough information to define
operations to perform by classes and therefore is investigated in
this paper in the context of the UML sequence diagram
generation