Synthesis and Testing of Tetramethylhelquat
This study reports a facile, three-step synthetic route to tetramethylhelquat - a model molecule chosen for the investigation of properties of a novel class of helical dications called helquats. Sonogashira coupling, N,N’-bisquaternisation and the key [2+2+2] cycloisomerisation lead to tetramethylhelquat without any involvement of chromatographic purifications. The developed synthetic procedure allows a multigram synthesis of tetramethylhelquat. This work also describes the ability of helquats to catalyse pharmaceutically attractive Povarov reaction. As helquats combine structural motifs of two interesting compound classes - helicenes and viologens - also their application potential is expected to be similarly rich. To this end, design of enantioselective catalysts, fluorescent dyes for microscopy, and biologically active species might benefit from the chemistry of helquats. The results of this study will be useful in further research of helquats.
Pernille Neve Petersen
Enzymatic Browning in Bananas
It is estimated that up to 30 % of the approx. 100 mil. Tons of bananas produced yearly are thrown
away due to enzymatic browning. This browning process, in bananas, leads the oxidation of dopamine to the pigment melanin, and is catalyzed by polyphenol oxidases (PPO). In the light of new research, I have shown, using the fungus Aspergillus niger, that (1) PPO protects bananas against pathogens and therefore is a part of the bananas immune response, and (2) there is a link between the ripening of bananas and PPO activity. This previously undocumented work has required unique improvements of described related research methods, as well as designing and applying a novel system for determining the ripening of bananas. The results show that the activity of PPO is highest in brown bananas. It can therefore be concluded that over-ripe banana waste products contain a high potential in the medicinal industry for fighting human infections.
Comparison of Three Finnish Berries as Sensitizers in a Dye-Sensitized Solar Cell
Harnessing solar energy in an efficient, low-cost way remains a challenge. Photoelectrochemical Dye-sensitized Solar Cells (DSCs or Grätzel cells) are proposed as an inexpensive, easy-to-manufacture alternative to conventional solar cells. The possibility of using common Finnish berries as dye-sensitizers in a DSC interested me. I wanted to know which of the three berries (strawberry, lingonberry and blackcurrant) was the most effective. A common food colorant in berries, anthocyanin, binds to the TiO₂ surface of the solar cell and absorbs incoming light to produce excited electrons. These electrons travel from the TiO₂ surface to the external circuit providing electric current. The energy conversion efficiency of the sensitized solar cells was measured to examine the effectiveness of the berries as sensitizers. In this empirical setup blackcurrant was the most suitable sensitizer for a DSC and it achieves the highest energy conversion efficiency of 0.0480%.
The New Magic Formula for Eliminating Bad Breath: C42H70O35
Bad breath is a common problem. The cause is usually bacteria that decompose, e.g., food particles in the oral cavity. Chemically or biologically active substances can fight the bacteria—the odorous substances can be bound by absorption agents. Gabriel Salg and Nicolas Scheidig wanted to fight the primary cause of bad breath, hydrogen sulphide and its methyl compounds with so-called cyclodextrins. These are produced from starches, contain absorption agents and are approved for use as food additives. The deodorisers, which have not previously been used for treating bad breath, work wonders: after rinsing with the aqueous cyclodextrin solution, breath and even garlic odour disappears.
Andris Alfrēds Avots
The Usage and Properties of Rigid Foam Polyurethane Material Derived from Tall Oil by using Cyclopenthane as a Blowing
In our part of the world where the winters are cold a well insulated house can increase the living quality and reduce the heating costs. When people are insulating their houses they can also protect the environment by using polyurethane foam made from tall oil, which is a paper making by-product and a great alternative to polyols derived from oil because it’s cheaper and is a renewable resource. Until now freons were used to create rigid foam polyurethane materials for the thermal insulation of places that have a fire hazard. In the near future these freons could be banned. In our work we developed an alternative to using freons- we substituted freons with c-penthane. This substance is environmentally friendlier than the freon gases, but it is also flammable. This is the reason why it hasn’t been used. We fulfilled our goal of making a fire-resistant thermal insulation material by using c-penthane. The material we made is suited for the forming of sandwich panels or injection moulding.
Mushroom Dyes for Tapestry Restoration
The aim of our work is to investigate the possibility to apply mushroom dyes for tapestry restoration. During the first year of research the technology of imbuing with mushroom dyes was developed and fastness to washing of imbued yarns’ colour was investigated. The most relevant parameters of imbued museum textile – lightfastness, acidity, and mechanical strength – were examined during the second and the third years of research. It was also discovered that lightfastness of imbued yarns’ colour can be improved by covering them with antioxidants. The results of research proved that the mushroom dyes are well suitable for restoration and the developed imbuing techniques could be offered to restorers. Moreover, a palette of 118 colour shades was made from the yarns and fabrics imbued with mushroom dyes.
Elena Alda Anna Bertola
Impregnation of a Natural Surgically Implantable Porous Structure for the Controlled Release of Antibiotics
With a solvent-anti-solvent process entirely developed in supercritical phase (SAS), some hydroxyapatite blocks for dental implantation have been impregnated with antibiotics. N-methyl-2-pyrrolidone (NMP)/CO2 60/40 m/m supercritical solution at 70 bar and 45°C in static condition has been used as process fluid for the transportation of antibiotic (tetracycline and amoxicillin) inside the nanometric hydroxyapatite structure. Antibiotic release from solution to hydroxyapatite has been obtained with a minimum contact time of 1 hour in static conditions by increasing solution composition until more than 70% of CO2 at 200-250 bar and 45 °C. During next stage of pure CO2 flushing at 250 bar and 45 °C takes place NMP evacuation. 5 mg of tetracycline for each gram of hydroxyapatite are obtained, whose 20% is released in a physiological solution. This load is 200 times greater than the one which can be obtained with a simple hydroxyapatite immersion in NMP and pentane liquid solutions.
Study of Eliminating Heavy Metal Ions in Waste Water using Low Cost Natural Absorbant
Purpose of this study is to investigate the elimination of heavy metals in waste water with hull with the most economic way. First 10ˉ³ Molar standard solutions of Lead II, Zink II, Cadmium II and Copper II ions were prepared in laboratory environment. When the solutions of heavy metals in grape seed, walnut shell and pumpkin seed hull was prepared and kept for a while it was observed that the solution with grape seed was observed to get wormy after 48 hours. As refinement cannot be done in such a solution, it was ceased to work with grape seed and the work was focused on pumpkin seed hull as it was seen that the properties of pumpkin seed to absorb heavy metals was high as the result of the attractions observed. With this study it is determined that pumpkin seed hull can refine the Cadmium metal present in waste water from 10 % up to 89.5%, Lead metal from 58% up to 91%, Zinc and Copper metals from 50% up to 60% and 88%.