The Investigation of Silica Removal in Reverse Osmosis Concentrate by Changing Design Parameters

Silica at high concentrations can precipitate and polymerize, forming scales on heat exchangers, boilers and turbines in industrial equipment, and on the feed side of the semi-permeable membranes in Reverse Osmosis (RO). Silica scale can cause decreased efficiency, increased treatment costs and, in some cases, irreversible damage. The removal of silica scale is challenging because it requires the handling of dangerous and hazardous chemicals. Therefore, much research has gone into the removal of soluble silica. The purpose of this research was to compare the overall effectiveness of silica removal in RO concentrate water with freshly precipitated Mg(OH)2 and Fe(OH)3,and calcined Hydrotalcite (HTC) by changing the design parameters adsorbent dose and pH. To complete this work, 15 experiments (12 batch experiments and 3 flow through experiments) were performed. Initial batch studies investigated and compared the effects of changing the dose and on silica removal for freshly precipitated Mg(OH)2 and Fe(OH)3,and calcined HTC. The results showed that, for all materials, an increased dose at pH 10 led to increased silica removal. Then, using the three materials, the effect of pH was investigated on silica removal. When the pH was increased from 9 to 11, trends in silica removal varied for the three materials. Furthermore, batch studies were completed on the three materials to determine the sorption density and sorption kinetics onto the solids. The sorption densities were used to determine the most applicable isotherm (Freundlich or Langmuir) and identify isotherm parameters for the materials. All three materials fit the Freundlich isotherm model and based on isotherm parameters, the largest adsorption capacity was determined to be HTC and the most intense adsorption was determined to be Fe(OH)3. The sorption kinetics were examined for zero, first and second order kinetics to determine a rate constant for silica adsorption reactions. It was discovered that all three materials fit the second order kinetics models and the uptake rates were determined to be 3.0 X 10-4 mg/L×min for Mg(OH)2, 9.0 X 10-5 mg/L×min for Fe(OH)3 and 7.0 X 10-5 mg/L×min for HTC at various doses. Using the results of the batch tests, a flow through system was constructed and used to examine the material’s capacities on a larger scale and determine if 70% silica removal can be maintained. The results showed that when the materials were compared, HTC could achieve the target percent silica removal at a lower dose than Mg(OH)2 and Fe(OH)3 but, all three materials could maintain silica removal on a large scale. This study provides important information for water treatment industries looking to remove soluble silica from water

Raman spectroscopy in bladder cancer diagnosis

Raman Spectroscopy can give a biochemical fingerprint of tissue and therefore could detect malignant changes in bladder tissue. In the introduction the basics of bladder cancer diagnosis and Raman Spectroscopy and the current status of research in this field is described. In chapter 2 we performed phantom measurements using a superficial probe which showed to measure more superficial and has a higher signal to noise ratio than a nonsuperfical probe. In chapter 3 this probe was tested in during cystoscopie. Thesignal to noise ratio, sensitivity and specificity of detecting urothelial carcinoma was higher for the superficial probe compared to the nonsuperficial probe. In chapter 4 we used this probe for 2D spatial measurements of a cystectomy specimen. In this chapter we found more uncertainty surrounding the tumor which could be explained by the fact that tissue surrounding the tumor is in transition into malignancy or that there is tissue heterogeniety. In chapter 5 we describe a bladder lesion registration and navigation tool. We tested it in a phantom model. Chipsoft, Coloplast, Eurocept Homecare, KARL STORZ Endoscopie Nederland B.V., Mayumana, MemidisPharma, Reinier de Graaf Gasthuis, St. Antonius ziekenhuis, Team WestlandLUMC / Geneeskund

Unbalanced reduction of nutrient loads has created an offshore gradient from phosphorus to nitrogen limitation in the North Sea

Measures to reduce eutrophication have often led to a more effective decline of phosphorus (P) than nitrogen(N) concentrations. The resultant changes in riverine nutrient loads can cause an increase in the N : Pratios of coastal waters. During four research cruises along a 450 km transect, we investigated how reductionsin nutrient inputs during the past 25 yr have affected nutrient limitation patterns in the North Sea. Thisrevealed a strong offshore gradient of dissolved inorganic N : P ratios in spring, from 375 : 1 nearshoretoward 1 : 1 in the central North Sea. This gradient was reflected in high nearshore N : P and C : P ratios ofparticulate organic matter (mainly phytoplankton), indicative of severe P deficiency of coastal phytoplankton,which may negatively affect higher trophic levels in the food web. Nutrient enrichment bioassays performedon-board showed P and Si limitation of phytoplankton growth nearshore, co-limitation of N and P ina transitional region, and N limitation in the outer-shore waters, confirming the existence of an offshore gradientfrom P to N limitation. Different species were limited by different nutrients, indicating that furtherreductions of P loads without concomitant reductions of N loads will suppress colonial Phaeocystis blooms,but will be less effective in diminishing harmful algal blooms by dino- and nanoflagellates. Hence, our resultsprovide evidence that de-eutrophication efforts in northwestern Europe have led to a large imbalance in theN : P stoichiometry of coastal waters of the North Sea, with major consequences for the growth, species composition,and nutritional quality of marine phytoplankton communities

Predicting Shine–Dalgarno Sequence Locations Exposes Genome Annotation Errors

In prokaryotes, Shine–Dalgarno (SD) sequences, nucleotides upstream from start codons on messenger RNAs (mRNAs) that are complementary to ribosomal RNA (rRNA), facilitate the initiation of protein synthesis. The location of SD sequences relative to start codons and the stability of the hybridization between the mRNA and the rRNA correlate with the rate of synthesis. Thus, accurate characterization of SD sequences enhances our understanding of how an organism's transcriptome relates to its cellular proteome. We implemented the Individual Nearest Neighbor Hydrogen Bond model for oligo–oligo hybridization and created a new metric, relative spacing (RS), to identify both the location and the hybridization potential of SD sequences by simulating the binding between mRNAs and single-stranded 16S rRNA 3′ tails. In 18 prokaryote genomes, we identified 2,420 genes out of 58,550 where the strongest binding in the translation initiation region included the start codon, deviating from the expected location for the SD sequence of five to ten bases upstream. We designated these as RS+1 genes. Additional analysis uncovered an unusual bias of the start codon in that the majority of the RS+1 genes used GUG, not AUG. Furthermore, of the 624 RS+1 genes whose SD sequence was associated with a free energy release of less than −8.4 kcal/mol (strong RS+1 genes), 384 were within 12 nucleotides upstream of in-frame initiation codons. The most likely explanation for the unexpected location of the SD sequence for these 384 genes is mis-annotation of the start codon. In this way, the new RS metric provides an improved method for gene sequence annotation. The remaining strong RS+1 genes appear to have their SD sequences in an unexpected location that includes the start codon. Thus, our RS metric provides a new way to explore the role of rRNA–mRNA nucleotide hybridization in translation initiation