Beim Kolikpferd stellt der Einsatz von Laxantien den wesentlichen Teil der konservativen Behandlung primärer Obstipationen des Zäkums und großen Kolons dar. Um die Obstipation zu erreichen muss das über eine Nasenschlundsonde eingegebene Abführmittel den Magen verlassen und den Dünndarm passieren. Dabei soll das Flüssigkeitsvolumen möglichst vollständig im Intestinaltrakt verbleiben, um effektiv die Ingesta zu durchfeuchten und so die Obstipation zu lösen. Je nach Art und Konzentration des gewählten Laxans werden Resorptions- und Sekretionsvorgänge an der Darmschleimhaut ausgelöst, die sich als Elektrolytverschiebungen oder Alterationen des Wasserhaushaltes im Blut zeigen können. Ziel dieser Studie war es, beim gesunden Pferd einen Einfluss der am häufigsten eingesetzten Laxantien auf die Magenentleerungszeit zu ermitteln. Zudem sollten Auswirkungen auf den Elektrolyt- und Wasserhaushalte untersucht werden. Für die vorliegende Studie wurde sechs gesunden, nüchternen, adulten Warmblutpferden abwechselnd je eines von 5 Laxantien über eine Nasenschlundsonde in den nüchternen Magen eingegeben: 1,8% Natriumsulfatlösung (Protokoll 1); 4,2% Magnesiumsulfatlösung (Protokoll 2); Paraffinöl (Protokoll 3); 25% Natriumsulfatlösung (Protokoll 4); 25% Magnesiumsulfatlösung (Protokoll 5). Als Kontrolle wurde Wasser verabreicht: 10 L Wasser (Protokoll 6); 2 L Wasser (Protokoll 7). Zur indirekten Messung der Magenentleerung wurde der flüssige Passagemarker D-(+)-xylose (0,5 g/kg KG als 10% Lösung) jedem Protokoll zugefügt mit mindestens einer Woche Auswaschzeit zwischen den einzelnen Protokollen. Zu festgelegten Zeitpunkten wurden EDTA-Blut- und Serumproben aus der Jugularvene entnommen. Die Serumkonzentration von D-Xylose wurde colorimetrisch untersucht. Die Zeit bis zum Erreichen der maximalen Serumkonzentration von D-Xylose (Tmax) wurde als Magenentleerungszeit angesehen. Zur Einschätzung des Wasserhaushaltes wurden Totalprotein, Albumin und Hämatokrit bestimmt. Der Elektrolythaushalt wurde anhand der Serumkonzentrationen von Natrium, Kalium, Chlorid, Magnesium und Gesamtkalzium beurteilt. Zudem wurde der Einfluss auf die Wasseraufnahme und die Kotkonsistenz grobsinnlich untersucht. Ergebnisse dieser Studie zeigen, dass weder isotone Natriumsulfatlösung noch Paraffinöl die Magenentleerungszeit im Vergleich zu Wasser beeinträchtigen. Isotone Magnesiumsulfatlösung als auch hypertone Lösungen salinischer Laxantien führen zu einer signifikanten Verzögerung der Magenentleerung im Vergleich zu Wasser. Nach 10-stündiger Nahrungskarenz führte die Applikation von Wasser bei gesunden Pferden zum Abfall der Serumkonzentrationen von Natrium, Kalium, Magnesium, Gesamtkalzium und Chlorid. Isotone Lösungen von Natriumsulfat (1,8%) und Magnesiumsulfat (4,2%) führten nach einmaliger Applikation zum signifikanten Anstieg der Serumkonzentrationen von Natrium bzw. Magnesium innerhalb der Referenzbereiche. Paraffinum liquidum hatte keine starke Alterationen des Elektrolythaushaltes zur Folge. Hypertone Natriumsulfatlösung (25%) verursachte Hypernatriämie sowie einen signifikanten Abfall der Kalium- und signifikanten Anstieg der Chloridkonzentration. Hypertone Magnesiumsulfatlösung (25%) verursachte Hypermagnesämie sowie eine signifikante Abnahme der Kalium- und Gesamtkalziumkonzentration. Keines der verabreichten Laxantien führte zur Dehydratation. Alterationen der Wasseraufnahme oder der Kotkonsistenz wurden ausschließlich durch hypertone Natriumsulfatlösung verursacht, die die Wasseraufnahme deutlich steigerte und vorübergehend dünnbreiigen Kotabsatz induzierte. Bei primären Obstipationen des großen Kolons muss bis zur Lösung der Obstipation meist eine mehrmalige Applikation von Abführmitteln erfolgen. Hypertone Natrium- bzw. Magnesiumsulfatlösung erhöht die Serumkonzentration von Natrium bzw. Magnesium signifikant und könnte eine klinische Hypernatriämie bzw. Hypermagnesiämie erzeugen. Aus diesem Grund sind isotone Lösungen zu bevorzugen. Außerdem ist Kolikpferden mit primärer Dickdarmobstipation, die mit salinischen Laxantien behandelt werden, freier Zugang zu Wasser zu gewähren, um den entstehenden Durst der Pferde zu stillen. Zusammenfassend ist die Verabreichung isotoner Natriumsulfatlösung zu empfehlen, weil dieses effektive Laxans weder die Magenentleerungszeit verzögert, noch starke Elektrolytimbalanzen verursacht. / The use of laxatives is crucial in the treatment of horses with cecal or large colon impaction. To reach the impacted mass, the laxative must leave the stomach and pass through the small intestine. The fluid volume should stay inside the gastro-intestinal tract to soften the intestinal contents and resolve the impaction. Depending on the type and concentration of the laxative, absorption and secretion can be triggered in the intestinal mucosa which might be shown as electrolyte abnormalities, or as alterations in the water balance in the blood. The aim of this study was to determine an influence of the most frequently used saline and lubricant laxatives on gastric emptying time in healthy horses. Furthermore the effect on electrolyte and water balance was to be investigated. Six healthy adult fasted Warmblood horses were used for this study which was performed with 5 laxatives, administered via nasogastric tube: 1.8% sodium sulfate (trial 1), 4.2% magnesium sulfate (trial 2), mineral oil (trial 3), 25% sodium sulfate (trial 4), 25% magnesium sulfate (trial 5). Water was used as control: 10 L water (trial 6), 2 L water (trial 7). For indirect measurement of gastric emptying the liquid passage marker D-(+)-xylose (0.5 g/kg bwt as 10% solution) was added to each trial with a minimum washout period of at least one week between the individual trials. EDTA blood and serum samples were taken from the jugular vein at predetermined time points. The serum concentration of D-xylose was analyzed colorimetrically. The time to reach peak serum concentration of D-xylose (Tmax) was considered as gastric emptying time. Total protein, albumin and PCV were chosen to evaluate water balance. Electrolyte balance was evaluated on the basis of the serum concentrations of sodium, potassium, chloride, magnesium and total calcium. Furthermore the impact on water uptake and fecal consistency was roughly examined. Isotonic solutions of sodium sulfate as well as mineral oil do not delay gastric emptying time compared to water. Isotonic solutions of magnesium sulfate as well as hypertonic solutions of saline cathartics significantly delay gastric emptying time in comparison to water. After ten hours of food restriction the administration of water decreased the serum concentrations of sodium, potassium, magnesium, total calcium and chloride in healthy horses. A single administration of isotonic solution of sodium sulfate (1.8%) or magnesium sulfate (4.2%) significantly increased serum sodium, respectively serum magnesium concentrations, within the reference range. Mineral oil did not alter electrolyte balance. Hypertonic solution of sodium sulfate (25%) caused hypernatremia, a significant decrease in potassium concentration and a significant increase in chloride concentration. Hypertonic solution of magnesium sulfate (25%) caused hypermagnesemia and a significant decrease in potassium and total calcium concentrations. None of the administered laxatives caused dehydration. Altered water uptake or fecal consistency was caused by hypertonic solution of sodium sulphate only, which considerably increased water consumption and transitionally induced runny feces. For treatment of simple large colon impactions, administration of laxatives usually has to be repeated, until the obstruction has resolved. Hypertonic solutions of sodium and magnesium sulfate significantly increase serum sodium or magnesium concentrations, respectively and may cause clinically hypernatremia or hypermagnesemia. Therefore isotonic solutions are preferable. Furthermore horses with simple large colon impaction, which are treated with saline cathartics need to have free access to water in order to satisfy their arising thirst. In summary it can be stated that the administration of isotonic solution of sodium sulfate is to be recommended, since this effective laxative does neither delay gastric emptying time nor leads to severe electrolyte alterations.

The kraft pulping process has been known for decades. The focus in kraft pulping has always been on better operation of the chemical recovery system. One of the targets is on deadload (sodium sulfate (Na2SO4) and sodium carbonate (Na2CO3)) reduction in white liquor. A model based on several literature references was developed to study the effect of deadload reduction. A base model was developed based on current mill operation. This base model was compared to the deadload reduction model. Overall improvement, such as operating cost saving and revenue generation was achieved from deadload reduction. Operating cost saving involves less deadload chemical in chemical recovery system, and less water that was associated with the deadload itself. Revenue generation involves generating more steam and heat from the recovery boiler that can be used for mill purposes or energy revenue. Two important variables to achieve deadload reduction are causticizing efficiency and reduction efficiency.

Στην παρούσα εργασία πραγματοποιήθηκε μελέτη της κινητικής της κρυστάλλωσης του Μιραμπιλίτη (δεκαένυδρο θειικό άλας), που είναι και το θερμοδυναμικά σταθερότερο άλας του θειικού νατρίου που κρυσταλλώνεται στις συνήθεις περιβαλλοντικές συνθήκες. Η μελέτη έγινε σε ασταθή υπέρκορα διαλύματα τα οποία παρασκευάζονται με διάλυση του θειικού νατρίου. Στην συνέχεια επιλέχθηκαν τρεις οργανοφωσφορικές ενώσεις προκειμένου να διερευνηθεί η επίδρασή τους στην κινητική της κρυστάλλωσης του Μιραμπιλίτη. Το κοινό χαρακτηριστικό αυτών των οργανοφωσφορικών ενώσεων είναι ότι έχουν ιονιζόμενες ομάδες στο μόριο τους και γι’ αυτό θεωρείται ότι μπορούν να δεσμεύουν είτε μέσω προσρόφησης ή με τον σχηματισμό επιφανειακών συμπλόκων, τα ενεργά κέντρα κρυστάλλωσης. / Our work is concerned with the investigation and inhibition of crystal growth for mirabilite. Mirabilite is a hydrated sodium sulfate salt and considers extremely hazardous for building materials as marble and concrete when it crystallizes heterogeneously in pores. The compounds tested with respect to their effect on the crystal growth of mirabilite were three organophosphorus compounds: HEDP, ATMP, HMDTMPA. Those organophosphorus compounds possesses ionizable groups and therefore are consider to be able to block by absorption the active growth sites forming possibly surface complexes.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [117]-123).

Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2005. / Empie, Jeff, Committee Chair ; Banerjee, Sujit, Committee Member ; Deng, Yulin, Committee Member. Includes bibliographical references.

M.Tech. / RNA interference (RNAi) is a gene silencing mechanism that uses short RNA duplexes to block gene expression. This mechanism has been widely explored to determine functions of genes. Furthermore, this phenomenon has been used to silence unwanted genes such as viral genes. RNAi has been successfully employed in non-mammalian organisms such as plants, where long dsRNAs (more than 30 bp) have been used without inducing non-specific effects. However, in mammalian cells, cytoplasmic dsRNAs of more than 30 bp trigger non-specific induction of many genes, which may result from the activation of dsRNA-dependent protein kinase (PKR) and 2’,5’-oligoadenylate synthetase (2’,5’-OAS), via the interferon response pathway. In this study, we describe a novel and simple strategy to overcome nonspecific effects induced by longer RNA duplexes. This strategy uses sodium bisulphite which is a mutagen that deaminates cytosine residue to uracil residues in order to introduce mutations in the sense strand of the duplex. Introduction of these mutations results in the formation of G:U pairings between the sense and antisense strands of the long hairpin RNA. RNA duplexes with mismatches have been shown to be able to prevent interferon induction in mammalian cells. According to the obtained results, long hairpins RNA with and without mismatches were unable to inhibit the expression of the target region, which was the U5 region of the HIV-1 subtype C LTR. The U5 region of the LTR is actively involved in the reverse transcription of HIV-1. Therefore silencing of this region would have led to the inhibition or reverse transcription blockage. Furthermore, data showed that the interferon response was induced when using these long hairpin RNA duplexes. Due to the sensitivity of mammalian cells, the action of sodium bisulphite could have stimulated certain genes of the interferon pathway. Even though hairpins constructed in this study were unable to prevent the induction of the interferon response pathway and also could not silence the target, this strategy of using sodium bisulphite has a great potential as shown by its ability to induce changes in cytosine residues and leaving other nucleotides unchanged.

Three artificial stream designs, termed Large Artificial Stream Units (LASUs), Raceways, and Channels, at two major scales (1700 L, 12.5 L and 20 L recirculated volume) were developed at the Institute for Water Research, Rhodes University, Grahamstown, in order to explore the possibilities of using indigenous rheophilic macroinvertebrates in routine toxicity tests. This study compared these systems, using 96h-EC50 values from sodium sulphate toxicity tests as the experimental response. Two local Ephemeroptera (Leptophlebiidae: Adenophlebia auriculata Eaton, and Baetidae: Afroptilum sudafricanum Lestage) were evaluated for their suitability in routine toxicity tests; and the possible effects of elevated salinity levels in South African rivers on the test species were assessed. Two sets of experiments with each mayfly species were conducted, following an unreplicated regression design. Dechlorinated tap water was used as the water source. Experiments in the Channels were repeated to determine experimental variability. Results were compared statistically by testing for overlap of 95% confidence limits (95%Cls) of EC50 values. The differences between A. auriculata EC50 values in the different systems were statistically significant (no overlap of 95%CLs), but they were not more variable than has been considered normal for biological systems (Coefficient of variation 20.1 %; ratio of greatest EC50 / smallest EC50 1.63). The differences were not related to the scale or the average current velocity characteristic of each stream design (average current velocity LASUs - Raceways - Channels 0.090 - 0.083 - 0.038 m/s). The Channels proved to be most efficient with regard to practical performance as they are portable and easily transportable, user-friendly, reliable, splash-free, cost effective to construct, and can easily be adapted to specific requirements. These systems are therefore recommended for regular use. The suitability of the two mayfly species for routine toxicity testing was evaluated. A. auriculata EC50 values showed a significant negative correlation with the corresponding average body-size (range 1476 - 1610 μm, mean 1555 μm). The different average body-sizes probably reflected the abundance of a certain size range present in the Palmiet River at the time of collection. Both species reacted similarly to Na₂S0₄ (similar slopes of the toxicity curves), identifying this salt as a slow acting toxicant. A. sudafricanum populations were more sensitive to Na₂S0₄ (EC50 3.404 g/L) than A. auriculata (EC50 8.090 g/L), probably because of its smaller body-size (mean 709 μm) and a lack of extremely tolerant individuals. In comparison to other freshwater macro invertebrates, including the standard toxicity test organism Daphnia spp., both mayfly species seemed to be moderately tolerant of Na₂S0₄; therefore there was no particular advantage to using these indigenous taxa rather than Daphnia spp. An assessment of the effects of elevated salinity/TDS levels on the test taxa yielded preliminary insights. A NaCI-EC50 for A. sudafricanum could be extrapolated and suggested a higher sensitivity to Na₂S0₄ than to NaCl. When Na₂S0₄ EC50 values of both species were compared to selected TDS levels of South African rivers, 4. auriculata would mostly not be affected, but A. sudafricanum might occasionally suffer from sub-lethal effects, depending on the sulphate proportion of the TDS. The South African guideline for TDS seemed to protect both species sufficiently.

Now when the interest is increasing to reach a sustainable infrastructure, one possibility SCA is experimenting with is the possibility to produce renewable hydrocarbons from black liquor which can be extracted from a Kraft process. However, when extracting the black liquor, a lot of sodium-based compounds are removed from the recovery process and when hydrocarbons are produced in SCA’s biorefinery, these compounds are caught in an aqueous solution. The aqueous solution is received at 50°C, and the sodium-based compounds are mainly sodium sulfate and sodium carbonate, where the solution do also contain organic compounds and a solvent that is used in the biorefinery.  This thesis focused on building a concept to extract sodium sulfate from the aqueous solution. The thesis did also include if any additional preparatory work needs to be done to the solution before extracting sodium sulfate. Finally, a flow chart that maps the energy needed for the process was created.  The method that was used was crystallisation by cooling the solution. By cooling the solution, sodium sulfates solubility decreases which will result in that sodium sulfate falls out of the solution as crystals. It was determined that the solvent that the solution contains should be extracted if the solvents boiling temperature is below 100°C. Further, by cooling the solution under stirring to 15°C with a residence time of 3 hours, unwanted compounds can be extracted. By later cooling the solution under stirring to 5°C with a residence time of 1 hour, it gave sodium sulfate decahydrate (Na2SO4·10H2O) with small amounts of organic compounds. By removing the water, the dry product reached a purity of 94wt% sodium sulfate with a yield of 12% (mass of dry product/mass of aqueous solution). This result reached the specific objectives that were set at the start of this thesis, which was to reach a purity of 90wt% sodium sulfate with a yield of 5%.  The energy intensity for evaporating the solvent is expected to be high. It highly depends on which solvent is used. However, this process can use the lowest quality of steam that is available from the pulp mill. It is expected that the cooling will require high amounts of cooling water and a high investment cost for the heat exchanger. Yet, this is a vital part of the process to reduce the need for coolers which is powered by electricity. / Nu när intresset ökar, för att nå en hållbar infrastruktur, så experimenterat SCA med möjligheten att producera förnybara kolväten från svartlut som kan extraheras från en sulfatprocess. Vid extrahering av svartluten tas dock mycket natriumbaserade föreningar bort från återvinningsprocessen och när kolväten produceras i SCA:s bioraffinaderi fastnar dessa föreningar i en vattenlösning. Den lösningen tas emot vid 50°C och de natriumbaserade föreningarna är huvudsakligen natriumsulfat och natriumkarbonat, där lösningen också innehåller organiska föreningar och ett lösningsmedel som används i bioraffinaderiet. Denna avhandling fokuserade på att bygga ett koncept för att extrahera natriumsulfat från vattenlösningen. Avhandlingen omfattade också om ytterligare förberedande arbete måste göras av lösningen innan man extraherar natriumsulfat. Slutligen skapades ett flödesschema som kartlägger den energi som behövs för processen. Metoden som bestämde sig för att användas var kristallisering genom kylning av lösningen. Genom att kyla lösningen minskar lösligheten av natriumsulfater vilket leder till att natriumsulfat faller ut ur lösningen som kristaller. Det bestämdes att lösningsmedlet som lösningen innehåller skulle extraheras om lösningsmedlets koktemperatur är under 100°C. Vidare, genom att kyla lösningen under omrörning till 15°C med en uppehållstid på 3 timmar, kan oönskade ämnen extraheras. Genom att senare kyla lösningen under omrörning till 5°C med en uppehållstid på 1 timme gav natriumsulfatdekahydrat (Na2SO4·10H2O) med små mängder organiska föreningar. Genom att avlägsna vattnet nådde den torra produkten en renhet av 94 vikt% natriumsulfat med ett utbyte av 12% (massa torr produkt/massa vattenlösning). Detta resultat nådde de specifika mål som sattes i början av denna avhandling, vilket var att nå en renhet av 90 vikt% natriumsulfat med ett utbyte på 5%. Energiintensiteten för att förånga lösningsmedlet förväntas vara hög. Det beror mycket på vilket lösningsmedel som används. Denna process kan dock använda den lägsta ångkvaliteten som finns tillgänglig från massafabriken. Det förväntas att kylningen kommer att kräva stora mängder kylvatten och höga investeringskostnader för värmeväxlaren. Ändå är detta en viktig del av processen för att minska behovet av kylare som drivs av elektricitet.

No description available.

Predator cues can influence how aquatic organisms respond to anthropogenic contaminants. This study examined the effects of predator cues on behavior, metabolic rate, and sulfate (as Na2SO4) toxicity in amphipods (Gammarus minus). Predator cues included alarm cue (macerated conspecifics) and kairomone from mosquitofish (Gambusia affinis). Amphipods decreased activity and increased time in refuge when exposed to alarm cue, and increased time in refuge when exposed to kairomone. While median lethal concentrations (96-h LC50) were not influenced by predator cues, analysis of dose response curves indicated that kairomone exposure increased amphipod sensitivity to mid-range concentrations of sulfate (500-1,000 mg/L). Amphipods increased oxygen consumption in response to kairomone but not alarm cue. The influence of predator cues on contaminant lethality can be dependent on the type of cue, and physiological endpoints such as metabolic rate may help explain the basis of observed interactions.