Linking micellar structures to hydrogelation for salt-triggered dipeptide gelators

Some functionalised dipeptides can form hydrogels when salts are added to solutions at high pH. We have used surface tension, conductivity, rheology, optical, confocal and scanning electron microscopy, 1H NMR and UV-Vis spectroscopy measurements to characterise fully the phase behaviour of solutions of one specific gelator, 2NapFF, at 25 °C at pH 10.5. We show that this specific naphthalene–dipeptide undergoes structural transformations as the concentration is increased, initially forming spherical micelles, then worm-like micelles, followed by association of these worm-like micelles. On addition of a calcium salt, gels are generally formed as long as worm-like micelles are initially present in solution, although there are structural re-organisations that occur at lower concentrations, allowing gelation at lower than expected concentration. Using IR and SANS, we show the differences between the structures present in the solution and hydrogel phases

English Vocabulary Acquisition via Computer Games

Šis pētījums ir balstīts uz uzskatu, ka datorspēles nesniedz nekādu ieguldījumu, bet tikai paaugstina iespēju izcelties vardarbīgām situācijām un, ka datorspēles ir radītas tikai lai pavadītu laiku. Šī pētījuma mērķis ir cīnīties ar uzskatu, ka datorspēles nesniedz pozitīvu vērtību Angļu valodas vārdu krājuma apguvē un attīstībā. Par pamatu šim pētījumam tika izmantota pašnovērošana (introspekcija) un atskats pagātnē (retrospekcija). Tika veikta aptauja, lai noskaidrotu datorspēļu ietekmi uz spēlētāju valodas attīstību, un tika saņemtas 20 atbildes. Rezultāti norādīja, ka datorspēles satur lielāku daudzumu ar plusiem nekā mīnusiem, tādējādi norādot uz datorspēļu pozitīvo ietekmi uz subjektu (spēlētāju) vārdu krājuma apgūšanu. Tomēr, šis pētījums ir tikai mazs solis uz daudz lielāku pētījumu, kas jāveic, lai noskaidrotu datorspēļu īsto ietekmi uz valodas attīstību. Atslēgas vārdi: datorspēles; vārdu krājuma apguve; pašnovērošana; atskats pagātnē; spēlētāji; valodas apguves stiliThis research paper is based on the belief that computer games give no contribution but increase the risk of violent behaviors emerging amongst gamers and that they are created just to pass the time. The goal of this research paper is to counteract the belief that computer games do not give beneficial value to English vocabulary acquisition and development. Introspection and retrospection were used as a method of this research. The survey to find out the computer games’ influence upon language development on gamers was carried out and 20 responses were received. The results revealed that computer games contain a larger number of pros than cons, stating the positive effect of computer games on gamers' vocabulary acquisition. However, this research paper is just a small step towards a much larger research which must be performed to reveal the true potential of computer games towards language development. Key words: computer games; vocabulary acquisition; introspection; retrospectio

Engrossing mathematical logic exercises for high school

Bakalaura darba mērķis bija izstrādāt saistošus vingrinājumus matemātiskajā loģikā vidusskolai, kas veicinātu formālās loģikas pielietojumu ikdienā. Darba gaitā autors pētīja psiholoģijas pētnieku nostādnes par kognitīvo procesu attīstību un tās stimuliem un izveidoja apskatu par loģiskas domas pedagoģiski psiholoģiskiem aspektiem. Pētījuma ietvaros autors aptaujāja skolēnus par viņiem aktuāliem kritērijiem “saistošu” vingrinājumu klasifikācijā. Saskaņā ar apkopoto informāciju tika izstrādātas vadlīnijas saistošu un pragmatisku vidusskolas kursa matemātiskās loģikas vingrinājumu noteikšanai un sastādīšanai. Autors veica mācību grāmatu kontentanalīzi un izstrādāja 15 matemātiskās loģikas vingrinājumu paraugus. Darbs satur anotācijas latviešu un angļu valodā, satura rādītāju, ievadu, četras nodaļas ar apakšnodaļām, secinājumus, izmantotās literatūras un avotu sarakstu, 2 pielikumus. Darbs sastāv no 41 lpp., tajā ir 14 attēli un 3 tabulas.The aim of the thesis was to create engrossing exercises for high school students in mathematical logic, which would promote formal logic use in everyday. The author studied different psychology researcher findings about development of cognitive processes and its stimulus and created review about psychological aspects of logical thinking in pedagogy. The author interviewed students about their topical criteria for the classification of exercises. Based on the information gathered guidelines were created for the creation of actual and pragmatic mathematical logic exercises for high school course. Author analyzed text books and created 15 mathematical logic exercise examples. Thesis contains abstract in Latvian and English, table of content, introduction, four chapters with subchapters, conclusions, used literature and references and 2 attachments. It consists of 41 page, contains 14 pictures and 3 tables

Colloidal carbon and silica : their use in solar energy

The aims of this thesis are to optimise the use of colloidal carbon and silica in photothermal solar selective surface coatings and colloidal silica in antireflection coatings. (i) Photothermal solar selective coatings. Using an effective medium theory (Maxwell Garnett equation) and the experimental determination of the conversion efficiency, the optimum volume fraction and film thickness of the colloidal carbon and silica coatings can be determined. The temperature stability of these coatings will also be discussed. (ii) Antireflection coatings. In studying the effect of the antireflection properties of the colloidal silica coatings with respect to the variation of the silica primary particle size, a determination of the optimum colloidal silica coating can be made. Chemical bath dipping procedures will be used in this thesis as a means of applying the coatings. This is seen as an economically attractive method in fabricating these films