Natural freeze crystallization : purification of aqueous Na2SO4 solutions with cold air

The aim of this thesis was to examine efficiency of freeze crystallization and eutectic freeze crystallization in purification of wastewater by imitating natural freezing. In addition, a mathematic model based on heat transfer to determine ice thickness and ice growth rate was examined. Also, the amount of sodium sulfate crystallized at the eutectic point was under investigation. In literature part, advantages and applications of the freeze crystallization are discussed, and possibility to apply it in Northern hemisphere winter weather conditions is under study. Furthermore, main sources of sodium sulfate from Finnish industries are described. The experiments were carried out in modified chest freezer, where a fan was placed in order to obtain laminar air flow inside. Picolog PT-104 data logger was used to monitor temperature changes in the salt-water solution, and constant temperature was maintained in the crystallizer with Lauda RP 850 thermostat. The impurity of formed ice layer was determined by weighing ice samples after experiment and again after 24 hours drying to full dryness in oven. Volume of salt-water solution was also measured after experiment. The highest purity of formed ice layer was obtained with small temperature difference and with long freezing time. On the other hand, the amount of crystallized sodium sulfate was its greatest with long freezing time and higher temperature difference. The results obtained by the mathematic model and empirical results did not differ significantly in most of the experiments. However, the difference increased when salt-water mixture reached its eutectic point, leading to simultaneous ice and salt crystallization. Eutectic point was reached only with the highest salt concentration with one exception. In these cases, calculated values were in many cases greater than the experimental ones. In winter weather conditions freeze crystallization is cost-effective wastewater treatment method and rather simple. Nonetheless, the efficiency and separation rate are strongly depended on ambient temperature and its changes

L'école de la chasse aux chiens courants / par Le Verrier de la Conterie ; Illustré de huit estampes de Bidinger, de bandeaux d'après Routar et des 27 figures techniques des éditions anciennes

Collection : Les maîtres de la vénerie ; ̊ 5

Flore complète de la France et de la Suisse (comprenant aussi toutes les espèces de Belgique) pour trouver facilement les noms des plantes sans mots techniques : 5338 figures représentant les caractères de toutes les espèces... (5e éd. revue et corrigée) / par Gaston Bonnier,... et G. de Layens,...

Collection : La Végétation de la France, Suisse et Belgique. 1re partie

Development of techniques for testing the effect of the E1 region on adenovirus integration /

Adenoviral vectors are currently the most widely used gene therapeutic vectors, but their inability to integrate into host chromosomal DNA shortened their transgene expression and limited their use in clinical trials. In this project, we initially planned to develop a technique to test the effect of the early region 1 (E1) on adenovirus integration by comparing the integration efficiencies between an E1-deleted adenoviral vector (SubE1) and an Elcontaining vector (SubE3). However, we did not harvest any SubE3 virus, even if we repeated the transfection and successfully rescued the SubE1 virus (2/4 transfections generated viruses) and positive control virus (6/6). The failure of rescuing SubE3 could be caused by the instability of the genomic plasmid pFG173, as it had frequent intemal deletions when we were purifying It. Therefore, we developed techniques to test the effect of E1 on homologous recombination (HR) since literature suggested that adenovirus integration is initiated by HR. We attempted to silence the E1 in 293 cells by transfecting E1A/B-specific small interfering RNA (siRNA). However, no silenced phenotype was observed, even if we varied the concentrations of E1A/B siRNA (from 30 nM to 270 nM) and checked the silencing effects at different time points (48, 72, 96 h). One possible explanation would be that the E1A/B siRNA sequences are not potent enough to Induce the silenced phenotype. For evaluating HR efficiencies, an HR assay system based on bacterial transfonmatJon was designed. We constmcted two plasmids ( designated as pUC19-dl1 and pUC19-dl2) containing different defective lacZa cassettes (forming white colonies after transformation) that can generate a functional lacZa cassette (forming blue colonies) through HR after transfecting into 293 cells. The HR efficiencies would be expressed as the percentages of the blue colonies among all the colonies. Unfortunately, after transfonnation of plasmid isolated from 293 cells, no colony was found, even at a transformation efficiency of 1.8x10^ colonies/pg pUC19, suggesting the sensitivity of this system was low. To enhance the sensitivity, PCR was used. We designed a set of primers that can only amplify the recombinant plasmid fomied through HR. Therefore, the HR efficiencies among different treatments can be evaluated by the amplification results, and this system could be used to test the effect of E1 region on adenovirus integration. In addition, to our knowledge there was no previous studies using PCR/ Realtime PCR to evaluate HR efficiency, so this system also provides a PCR-based method to carry out the HR assays.

The isolation, partial purification and preliminary characterization of a growth factor from chick embryo brains

Chicl( brain growth factor (CBGF) is a mitogen isolated from embryonic chick brains thought to have a potential role as a trophic factor involved in nerve dependent amphibian limb regeneration. In addition, CBGF stimulates 3H-thymidine incorporation in chick embryo brain astrocytes in vitro. In this study, cultured chick embryo brain non-neuronal cells were employed in a bioassay to monitor CBGF activity throughout various stages of its pllrification. Cell culture and assay conditions were optimized. Nonneuronal cells grew best on collagen-coated culture dishes in complete medium, were most responsive to a growth stimulus [10% fetal bovine serum (FBS)] at the second and third subcultures, and were healthiest when rendered "quiescent" in medium supplemented with 1% FBS. The most effective bioassay conditions consisted of a minimum 14.5 hour "quiescence" time (24 hours was used), a 6 hour "prestimulation" time, and a 24 hour 3H-thymidine labeling time. Four-day subconfluent primary non-neuronal cells consisted of 6.63% GFAP positive cells; as a result cultures were thought to be mainly composed of astroblasts. CBGF was purified from 18-day chick embryo brains by ultrafiltration through Amicon PM-30 and YM-2 membranes, size exclusion chromatography through a Biogel P6 column, and analytical reverse-phase high-performance liquid chromatography (rp-HPLC). The greatest activity resided in rp-HPLC fraction #7 (10 ng/ml) which was as effective as 10% FBS at stimulating 3H-thymidine incorporation in chick embryo brain nonneuronal cells. Although other researchers report the isolation of a mitogenic fraction consisting of 5'-GMP from the embryonic chick brain, UV absorbance spectra, rp-HPLC elution profiles, and fast atom bombardment (FAB) mass spectra indicated that CBGF is neither 5'-GMP nor 51-AMP. 2 Moreover, commercially available 5t-GMP was inhibitory to 3H-thymidine incorporation in the chick non-neuronal cells, while Sf-AMP had no effect. Upon treatment with pronase, the biological activity of fraction P6-3 increased; this increase was nearly 30% greater than what would be expected from a simple additive effect of any mitogenic activity of pronase alone together with P6-3 alone. This may suggest the presence of an inhibitor protein. The bioactive component may be a protein protected by a nucleoside/nucleotide or simply a nucleoside/nucleotide acting alone. While the FAB mass spectrum of rp-HPLC fraction #7 did not reveal molecular weight or sequence information, the ion of highest molecular weight was observed at m/z 1610; this is consistent with previous estimations of CBGF's size. 3

Transfection of newt blastema mesenchyme using the techniques of lipofection and direct gene transfer

The regenerating amphibian limb provides a useful system for studying genes involved in the establishment of positional information. While a number of candidate genes that may playa role in pattern formation have been identified, their function in vivo is unknown in this system. To better ascertain the role of these genes, it would be useful to be able to alter their normal patterns of expression in vivo and to assess the effects of this misexpression on limb pattern. In order to achieve this, a method of introducing a plasmid containing the eDNA of a gene of interest into a newt blastema (a growth zone of mesenchymal progenitor cells) is needed. Unfortunately, most commonly used transfection techniques cannot be used with newt blastema cells. In this study, I have used the techniques of lipofection and direct gene transfer to introduce plasmid DNA containing reporter genes into the cells of a regenerating newt limb. The technique of lipofection was most effective when the blastema cells were transfected in vitro. The optimal ratio for transfection was shown to be 1:3 DNA:Lipofectin (W/w) , and an increase in the amount of DNA present in the mixture (1:3 ratio maintained) resulted in a corresponding increase in gene expression. The technique of direct gene transfer was used to transfect newt blastema cells with and without prior complex formation with Lipofectin. Injection of plasmid DNA alone provided the most 3 promising results. It was possible to introduce plasmid DNA containing the reporter gene ~-galactosidase and achieve significant gene expression in cells associated with the injection site. In the future, it would be interesting to use this technique to inject plasmid DNA containing a gene which may have a role in pattern formation into specific areas of the newt blastema and to analyze the resulting limb pattern that emerges.

Remembering Lessons Learned: knowledge management techniques for building generational memory

A presentation made at the CAUT Librarians Conference in Ottawa, Ontario in October 2005.