Spectroscopic studies of a phosphoinositide-binding peptide from gelsolin: behavior in solutions of mixed solvent and anionic micelles

The peptide G(150–169) corresponds to a phosphatidylinositol 4,5-bisphosphate (PIP2) and filamentous actin (F-actin) binding site on gelsolin (residues 150–169, with the sequence KHVVPNEVVVQRLFQVKGRR). The conformation of this peptide in trifluoroethanol (TFE) aqueous solution was determined by 1H nuclear magnetic resonance as the first step toward understanding the structural aspects of the interaction of G(150–169) and PIP2. The circular dichroism experiments show that G(150–169) adopts a predominantly alpha-helical form in both 50% TFE aqueous solution and in the presence of PIP2 micelles, therefore establishing a connection between the two conformations. 1H nuclear magnetic resonance experiments of G(150–169) in TFE co-solvent show that the helical region extends from Pro-154 to Lys-166. The amphiphilic nature of this helical structure may be the key to understanding the binding of the peptide to lipids. Sodium dodecyl sulfate micelle solution is used as a model for anionic lipid environments. Preliminary studies of the conformation of G(150–169) in sodium dodecyl sulfate micelle solution show that the peptide forms an alpha-helix similar to but with some structural differences from that in TFE co-solvent. Fluorescence experiments provide evidence of peptide clustering over a narrow range of peptide/PIP2 ratios, which is potentially relevant to the biological function of PIP2

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

Peptide conjugate hydrogelators

Molecular gelators are currently receiving a great deal of attention. These are small molecules which, under the appropriate conditions, assemble in solution to, in the majority of cases, give long fibrillar structures which entangle to form a three-dimensional network. This immobilises the solvent, resulting in a gel. Such gelators have potential application in a number of important areas from drug delivery to tissue engineering. Recently, the use of peptide-conjugates has become prevalent with oligopeptides (from as short as two amino acids in length) conjugated to a polymer, alkyl chain or aromatic group such as naphthalene or fluorenylmethoxycarbonyl (Fmoc) being shown to be effective molecular gelators. The field of gelation is extremely large; here we focus our attention on the use of these peptide-conjugates as molecular hydrogelators

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

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