Coconut (Cocos nucifera L.) is native to the regions between 20oN and 20oS of the Equator, where it plays a significant socioeconomic role in the local communities. There it is referred to as ’The Tree of Life’, a eulogistic epithet describing its versatile use - more than 100 edible and non-edible products can be produced from it. Therefore the coconut palm is grown in about 90 tropical countries on more than 10 millions ha of land (Hamon et al., 1999). Although coconut has a high local socioeconomic reputation, its production is experiencing many problems and consequently the area planted with this crop is declining. The conventional breeding approach using seed to replant land is very expensive due to the low production of seed for planting, and even when elite germplasm is available it takes decades to multiply up enough planting material for new areas (Adkins et al., 1999). Hence over the past 40 years research has been directed towards developing a new technique for the micropropagation of coconut using somatic embryogenic approach. Throughout this time however one conclusion is repeatedly made – coconut is very recalcitrant to somatic embryogenesis. And although the many obstacles to this are slowly being reduced, in order to successfully micropropagate coconut on a large scale bottlenecks in the protocol still exist, and those include inconsistency of the embryogenic response by explanted tissues, poor somatic embryo maturation and germination, low regeneration rate of the new plantlets and long time required to produce plants (1.5 years) (Samosir et al., 1998). These bottlenecks and other problems were researched in the present study with the aim of trying to speed up the efficiency of coconut somatic embryogenesis process. Hence this thesis had the objectives to identify a starting protocol for coconut somatic embryogenesis; to select an appropriate for aim that explant; to optimize the production of embryogenic callus; to increase the rate of initiating coconut somatic embryos; to improve the maturation of somatic embryos and their germination efficiency; and to optimize the regeneration rate of the new plantlets. In order to identify a starting protocol, preliminary work was conducted, where existing protocols for coconut somatic embryogenesis were compared in their efficiency to induce somatic embryos. The protocol that stood out as the best in producing most embryogenic callus and subsequently embryos, as well as having the least dead (in culture) explants, was that of Nikmatullah (2001). Therefore the latter was chosen to be used as a starting protocol for this study. New sources of explants were investigated during the current work as well, using tissues from different parts of in vitro derived 8 months old coconut plantlets. Those however have shown to be unsuitable for somatic embryogenesis, since only non-embryogenic callus was developed by some of the inoculated tissues. The immature inflorescence explants were superior in producing embryogenic callus and somatic embryos; therefore they were selected as the preferred explant source to use in the next steps of the current study. Optimizing the production of embryogenic callus was the first issue to address during the core work of this project. As a result of that the culture conditions were considerably improved by using vessels with larger headspace-medium ratio (3:1), as well as by selecting younger immature inflorescences and transversely segmenting the top half of the inflorescence spikes into smaller size (1 mm) sections. Further improvement was possible by studying the make up of the callus growth media. Amongst the administered for that purpose substances the applied together polyamines spermine (0.10 µM) and putrescine (7.5 mM) have proven to play a notably positive role in the induction of callus from coconut immature inflorescence explants. Thidiazuron (TDZ, 10 µM) too has shown a potential to improve the efficiency of the initial stage of coconut somatic embryogenesis, but only when applied in conjunction with other cytokinins (eg. BAP and 2iP). Smoke-saturated-water (SSW, 10 %) could only slightly diminish the amount of necrotising cultured explants, and high 2,4-D concentrations could not support the induction of callus from immature coconut inflorescences. Collectively taken, as a result of this current study the production of callus was improved by 300 %. The rate of coconut somatic embryos formation was as well significantly increased (over 300 %), by the simultaneous application of suspension culture step, spermine (0.01 µM), SSW (10 %) and high auxin concentration (500 µM). Nevertheless the presence of TDZ and other cytokinins in the medium, as well as the absence of activated charcoal, were found to be unable to positively influence the somatic embryogenesis process. Despite the considerable improvements made in the efficiency of inducing callus and initiating embryos, the poor maturation and germination (eg. 5 %, Verdeil et. al., 1999) of somatic embryos still remained a bottleneck to the whole somatic embryogenesis procedure. Therefore further work was conducted in that direction and discovered that embryo maturation and germination rate can be elevated to 55 % by administering ancymidol (30 µM) to the somatic embryo maturation medium. This plant retardant has exhibited here three potential modes of action towards the cultured coconut somatic embryos: a) as a promoter of somatic embryo maturation and germination; b) as a preventor of pre-germination death of the somatic embryos; and c) as a preserver of non-germinating somatic embryos, that still can possess the potential to germinate in the future. The work during the next step of the process – regeneration of the new plantlets – has shown that the omission of plant growth regulators from the media was crucial for the development of germinated embryos into new plantlets, where otherwise no plant regeneration occurred at all. The achieved here plantlet regeneration rate in the PGR-free medim was 56 %, which is higher than the previously reported 20 % regeneration rate (Verdeil et al., 1994) for coconut plantlets produced from immature inflorescences explants. As a result of this current work a new method was developed for somatic embryogenesis of coconut from immature inflorescences explants (Fig. 9.2). The overall efficiency of this protocol is over three times higher than that of the starting protocol (Nikmatullah, 2001) selected during the preliminary work. Furthermore, when using this new method the entire duration for regenerating clonal coconut plantlets (up to the stage of first root and shoot emerging) takes up to 8 months, which is the shortest reported time for producing coconut plantlets via somatic embryogenesis (eg. 36 months from inflorescences explants (Verdeil et. al., 1999) and 18 months from sliced zygotic explants (Samosir, 1999, Fig. 9.2), presenting an additional valuable advantage of this newly developed method, from the perspective of the potential to micropropagate coconut on a commercial scale.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Cheryl Ward, Florida State University, College of Arts and Sciences, Dept. of Anthropology. Title and description from dissertation home page (viewed Jan. 26, 2006). Document formatted into pages; contains ix, 161 pages. Includes bibliographical references.

The Female Athlete Triad, consisting of the interrelated conditions of low energy availability, leading to menstrual disturbances and low bone mineral density, is commonly diagnosed amongst excessively exercising women. The American College of Sports Medicine emphasizes that the underlying factor of the Triad is a discrepancy between dietary energy intake and the energy requirements needed to support high levels of physical activity in addition to other homeostatic and physiological bodily processes. Although low energy availability is largely recognized as a causative factor for amenorrhea and low bone density, no studies to date have examined specific macro- and micro-nutrient intake relating to bone mineral density in the female athlete population. The hypothesis to be tested was that a difference in the intake of specific nutrients between athletes with menstrual disturbances (amenorrheic) and regularly menstruating (eumenorrheic) athletes contributes to low bone mineral density in female athletes exhibiting symptoms of the Triad. Methods: 4-day food records were collected from 118 females, ages 14-23 years, who exhibited weight within the normal range. 68 participants were amenorrheic athletes (AA), 24 participants were eumenorrheic athletes (EUM), and 26 participants were non-exercising females within the same age group (non-athletes: NA). Serum levels of vitamin D, phosphorus, calcium, and estradiol were also collected. Results: In contrast to previous studies, there was no difference in energy availability between the AA, EUM, and NA groups. The groups did differ in their intake of several macro-and micro-nutrients, and many of these nutrients correlated significantly with lumbar spine BMD. In a multivariate model that included vegetable and total proteins, soluble, insoluble and total dietary fiber, pectins, phytic acid, natural folate, calcium intake, vitamin D intake, serum vitamin D levels, and % calories from saturated fatty acids (SFA), only dietary fiber remained negatively associated and % calories from SFA positively associated with lumbar spine BMD. Conclusions: Dietary fiber has a significant inverse association and % calories from SFA a positive association with lumbar spine BMD, even after controlling for other nutrient intake and serum levels and intake of Vitamin D and calcium. Therefore, fiber and saturated fat may exert effects unrelated to vitamin D status and overall energy availability to impact bone density. Nutrition guidelines for female athlete triad patients need to be reassessed.

Seafood is the number one source of essential fatty acids, particularly, long-chain polyunsaturated fatty acids (LC-PUFA) in the human diet. As global population growth eventually surpasses what the world's wild commercial stocks can provide, reliance on the aquaculture industry to expand production will continue to increase in order to meet the demands of consumers worldwide. Currently, fluctuations in supply and cost coupled with environmental sustainability and contaminant concerns have motivated the aquaculture industry to research alternative lipid sources and feeding strategies in order to reduce the reliance on marine-derived resources. For most cultured species, replacing fish oil with terrestrial plant-based lipid sources is a minor dietary modification that has little consequence on production performance. However, fish raised on these plant-based lipid alternatives contain considerably higher medium chain polyunsaturated fatty acids (MC-PUFA) and n-6 fatty acids and less beneficial LC-PUFA and n-3 fatty acids within the fillets, thus negatively impacting the nutritional value of cultured seafood to the consumer. In order to alleviate this problem, producers can employ finishing strategies to restore fillet LC-PUFA content prior to harvest. As a complement to this approach, provision of dietary saturated fatty acids (SFA) and/or monounsaturated fatty acids (MUFA) in lieu of MC-PUFA appears to maximize the retention of LC-PUFA deposition during the grow-out period and may increase deposition during finishing. Accordingly, my objectives were to 1) assess whether the SFA, MUFA, and MC-PUFA content of the alternative lipid affected LC-PUFA levels in Nile Tilapia fed reduced fish oil feeds; and 2) using the optimal alternative lipid identified in the first objective, assess increasing fish oil replacement rates in conjunction with finishing to maximize product nutritional value and minimize fish oil usage in Nile Tilapia culture. To address the first objective, I assessed production performance and tissue composition of Nile Tilapia fed diets containing fish oil or blends of fish oil and various soybean-derived alternative lipids. Quadruplicate tanks of juvenile Nile Tilapia were fed diets containing fish oil (FISH, high in LC-PUFA) or a 50:50 blend of fish oil and standard (STD-SO, high in MC-PUFA), saturated fatty acid-enriched (SFA-SO, high in SFA), low α-linolenic (LO-ALA-SO, high in MC-PUFA), or hydrogenated (HYD-SO, high in MUFA) soybean oil for 16 weeks. Partial replacement of fish oil with soybean oils did not significantly affect production performance with the exception of the HYD-SO diet which yielded significantly reduced growth efficiency in comparison with some of the experimental diets, though not the FISH control. Despite distinctly different dietary fatty acid profiles, fillet fatty acid composition was similar among fish fed the FISH, SFA-SO, and HYD-SO diets. However, feeding the STD-SO and LO-ALA-SO diets resulted in significant enrichment of less desirable MC-PUFA and n-6 fatty acids within the fillet. Fillet LC-PUFA levels were equivalent among all groups despite the 50% reduction in dietary LC-PUFA intake among fish fed the soybean oil-based feeds. Based on these results, incorporation of STD-SO, SFA-SO, or LO-ALA-SO could be used as partial replacements for fish oil in Nile Tilapia feeds without impairing production performance, though SFA-rich soybean oils appeared to be the best alternative for maintaining a more "fish oil"-associated fillet fatty acid profile. Accordingly, the SFA-enriched soybean oil was selected for further study in the second objective trial that evaluated the effects of graded levels of fish oil replacement without or without implementation of finishing periods on production performance and fillet fatty acid composition. Nile Tilapia were fed feeds containing 100% fish oil (100-FO), the previously assessed SFA-enriched soybean oil (100-SFA-SO), or blends of fish oil and SFA-enriched soybean oil (50-SFA-SO, 75-SFA-SO). Triplicate groups of fish were fed the aforementioned diets exclusively throughout the feeding trial (100-SFA-SO unfinished, 75-SFA-SO unfinished, 50-SFA-SO unfinished) or in conjunction with 4 or 8 weeks of finishing with the 100-FO feed (100-SFA-SO + 4 wks, 100-SFA-SO + 8 wks, 75-SFA-SO + 4 wks, 75-SFA-SO + 8 wks, 50-SFA-SO + 4 wks, 50-SFA-SO + 8 wks) for a total of 20 weeks. Production performance was unaffected by dietary inclusion of SFA-enriched soybean oil when fed exclusively or in combination with fish oil, though growth performance was lower than observed in the previous trial and likely confounded by behavioral interactions and frequent spawning. After 12 weeks of consuming the SFA-enriched soybean oil grow-out diets, fillet levels of n-3 LC-PUFA were not statistically different from 100-FO control levels despite different levels of dietary inclusion. However, the high dietary levels of SFA in the experimental feeds did not translate into increased fillet SFA content, suggesting selective retention of LC-PUFA at the expense of fillet SFA. Finishing for 4 or 8 weeks increased fillet n-3 LC-PUFA content in all groups, though it appears that the 50- and 75-SFA-SO diets were more successful in maintaining acceptable health promoting n-3:n-6 ratios. Based on these results, SFA-enriched soybean oil-based feeds can be used as a cost-saving measure during grow-out, and the effects of these feeds on fillet fatty acid profile can be reversed to a considerable extent in as little as 4 weeks by implementing a finishing period prior to harvest. This approach is a promising strategy for minimizing fish oil usage while maximizing product value of cultured Nile Tilapia.

abstract: One of the most economical and viable methods of soil improvement is dynamic compaction. It is a simple process that uses the potential energy of a weight (8 tonne to 36 tonne) dropped from a height of about 1 m to 30 m, depending on the project requirement, on to the soil to be compacted hence densifying it. However, dynamic compaction can only be applied on soil deposits where the degree of saturation is low and the permeability of the soil mass is high to allow for good drainage. Using dynamic compaction on saturated soil is unsuitable because upon application of the energy, a part of the energy is transferred to the pore water. The technique also does not work very well on soils having a large content of fines because of the absence of good drainage. The current research aims to develop a new technology using biogenic gas production to desaturate saturated soils and extend the use of dynamic compaction as a ground improvement technique to saturated soils with higher fines content. To evaluate the feasibility of this technology an experimental program has been performed. Soil columns with varying soil types have been saturated with substrate solution, resulting in the formation of nitrogen gas and the change in soils volume and saturation have been recorded. Cyclic triaxial tests have been performed to evaluate the change in volume and saturation under elevated pressure conditions and evaluate the response of the desaturated soil specimens to dynamic loading. The experimental results showed that soil specimens treated with MIDP under low confinement conditions undergo substantial volume expansion. The amount of expansion is seen to be a factor of their pore size, which is directly related to their grain size. The smaller the grain size, smaller is the pore size and hence greater the volume expansion. Under higher confining pressure conditions, the expansion during gas formation is suppressed. However, no conclusive result about the effect of the desaturation of the soil using biogenic gas on its compactibility could be obtained from the cyclic triaxial tests. / Dissertation/Thesis / Data sheets / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

Durante um acidente em uma usina nuclear, a integridade do vaso pressurizado deve ser assegurada. Em resposta a um possível derretimento do combustível nuclear, a atual geração de usinas possui um sistema para a injeção de água potável na cavidade do vaso pressurizado com intuito de resfriar sua parede, prevenindo danos a sua estrutura e evitando o vazamento de material radioativo. Esse estudo considerou o uso de água marinha como refrigerante para inundar a cavidade do vaso pressurizado combinado com a fixação de um estrutura porosa em forma de grade em sua parede externa como meio de aprimorar a margem de segurança durante a contenção de acidentes. Experimentos de longa duração para a ebulição em piscina de água marinha artificial foram conduzidos em uma superfície circular de cobre plana com 30 mm de diâmetro. Foi encontrado um fluxo de calor crítico de 1; 6 MW/m2 sob pressão atmosférica. Esse valor é significantemente maior que aquele obtido (1; 0 MW/m2) nas mesmas condições experimentais. Foi verificado que os depósitos de sais marinhos podem aumentar a molhabilidade e a capilaridade da superfície de teste, aprimorando assim o fluxo crítico. Combinando a água marinha e a fixação da estrutura porosa sobre a superfície de teste, verificou-se um melhora no coeficiente de transmissão de calor e no fluxo de calor crítico de até 110 % (2; 1 MW/m2), quando comparado a água destilada na superfície limpa, sem a instalação da estrutura. Após os experimentos, foi identificado que muitos dos poros presentes nas superfícies da estrutura porosa encontravam-se bloqueados devido ao aglutinamento de sais marinhos. Isso levou a conclusão que o aumento no valor do fluxo crítico observado para a água marinha artificial ocorreu devido, principalmente, a separação das fases líquida e gasosa do fluido na região próxima a superfície de teste, efeito proporcionado pela forma de grade da estrutura porosa, e ao aumento da molhabilidade e capilaridade da superfície devido a formação dos depósitos marinhos. / During a severe nuclear power plant accident, the integrity of the reactor pressure vessel must be assured. In response to a possible fuel meltdown, operators of the current generation of nuclear power plants are likely to inject water into the reactor pressure vessel to cool down the reactor vessel wall, preserving its integrity and avoiding leakage of radioactive material. This study considers the use of seawater to flood a reactor pressure vessel combined with the attachment of a honeycomb porous plate (HPP) on the vessel outer wall as a way to improve the safety margins for in-vessel retention of fuel. In long-duration experiments, saturated pool boiling of artificial seawater was performed with an upward-facing plain copper heated surface 30 mm in diameter. The resulting value for critical heat flux (CHF) was 1; 6 MW/m2 at atmospheric pressure, a value significantly higher than the CHF obtained when the working fluid was distilled water (1; 0 MW/m2). It was verified that sea-salt deposits could greatly improve surface wettability and capillarity, enhancing the CHF. The combination of artificial seawater and an HPP attached to the heated surface improved the boiling heat transfer coefficient and increased the CHF up to 110% (2; 1 MW/m2) as compared to distilled water on a bare surface. After the artificial seawater experiments, most of the wall micropores of the HPP were clogged because of sea-salt aggregation on the HPP top and bottom surfaces. Thus, the CHF enhancement observed in this case was attributed mainly to the separation of liquid and vapor phases provided by the HPP channel structure and improvement of surface wettability and capillarity by sea-salt deposition.

O crescimento da demanda por minério de ferro e a necessidade de melhoria nos terminais portuários, forçaram os portos a pensar e criar alternativas que refletissem em aumento de capacidade. Assim como os portos, as cidades ao redor dos terminais cresceram e avançaram sobre o território portuário, dificultando e até mesmo impedindo expansões físicas. Pensar e recriar conceitos que envolvam melhorias em todo o sistema produtivo é ter um olhar inovador para o processo e oferecer soluções que permitam aumento de capacidade, utilizando os recursos já existentes. No âmbito de se avaliar tais alternativas, foi utilizado um modelo de simulação de eventos discretos que possibilitou testar cenários de aumento de capacidade sem que para isso houvesse a necessidade de interferência na estrutura física, mas sim no tipo de produto movimentado e em mudanças nas atuais variáveis do sistema. / The iron ore demand and the need for improvement at the terminals forced the ports think and create alternatives that reflected in the incensement of capacity. In addiction with this growth, the cities around the terminals have grown and start to break into the port territory, making physical expansions hard to implement. To think and recreate concepts involving improvements throughout the production system is to have an innovative look at the process and offer solutions to increase capacity, using the existing resources. In the context of evaluating such alternatives, it was used a discrete events simulation model that enabled testing scenarios of capacity increase without interference in the physical structure, but in the quantity of different products types in the terminal and also changings in the system variables.

A lipoproteína de alta densidade (HDL) tem várias ações protetoras contra o desenvolvimento de doenças cardiovasculares, como remover o excesso de colesterol dos tecidos periféricos. No entanto, outros aspectos do metabolismo da HDL, como o transporte de colesterol das outras classes de lipoproteínas para a HDL devem ser avaliados para verificar a sua ação protetora. Sendo assim, nosso objetivo foi verificar, em hamsters, se a dieta hiperlipídica altera fatores relacionados ao metabolismo da HDL, tais como a composição da fração HDL e a transferência simultânea de lípides para a HDL. Trinta e nove hamsters Golden Syrian adultos machos receberam uma dieta hiperlipídica contendo 0,5% colesterol e 10% de óleo de coco (n=20, grupo dieta hiperlipídica) ou uma ração comercial usual (n=19, grupo controle) por 15 semanas. Os animais foram sacrificados e amostras de sangue foram coletadas para determinação do perfil lipídico, atividade da paroxonase 1 (PON1), da proteína de transferência de éster de colesterol (CETP) e da proteína de transferência de fosfolípides (PLTP), bem como a composição em lipídes da fração HDL. A transferência simultânea de colesterol livre (CL), éster de colesterol (EC), triglicérides (TG) e fosfolípides (FL) é baseada na troca de lípides ocorrida entre uma nanoemulsão lipídica artificial, marcada radioativamente com 14C-CL e 3H-TG ou 14C-FL e 3H-EC, e a HDL. Após precipitação química da nanoemulsão e das demais lipoproteínas, a capacidade da HDL em receber lípides foi quantificada pela medida da radioatividade presente na HDL. Além disso, a aorta e o fígado dos hamsters foram coletados para a determinação da composição em lípides e para análise histológica. Em relação ao perfil lipídico o colesterol total, HDL-C, n-HDL-C, FL, CL e EC foram maiores no grupo dieta hiperlipídica comparado ao grupo controle, já a concentração de TG não diferiu entre os grupos. A concentração de CL e EC da fração HDL foram maior no grupo dieta hiperlipídica. A transferência de 14C-CL, 3H-TG, 14C-FL e 3H-EC, bem como a atividade da CETP e da PLTP foram maiores no grupo dieta hiperlipídica. A atividade da PON1 não diferiu entre os grupos. A composição de CL da aorta foi maior no grupo dieta hiperlipídica comparado ao controle, no entanto o diâmetro interno e externo da aorta não diferiu entre os grupos. No grupo dieta hiperlipídica, a composição de EC, CL, TG e FL do fígado e o diâmetro dos hepatócitos foi maior do que no grupo controle. Dessa forma, a dieta hiperlipídica, i.e., enriquecida com colesterol e gordura saturada, em hamsters, modifica a composição em CL e EC da fração HDL, a sua capacidade em receber lípides, bem como outros aspectos relacionados ao seu metabolismo, o que pode alterar as propriedades antiaterogênicas da HDL. / High density lipoprotein (HDL) is known to protect against cardiovascular disease by removing the excess of cholesterol from peripheral tissues. However, other aspects of the HDL metabolism, as the transport of cholesterol of the other classes of lipoproteínas for the HDL should be sought to evaluate its protective action. Here, we tested the hypothesis whether a hyperlipidemic diet, in hamsters, alters the composition of the HDL fraction and ability of HDL to simultaneously receive lipids. Thirty-nine adult male Golden Syrian hamsters were fed hyperlipidemic diet containing 0.5% cholesterol and 10% coconut oil (n=20, hyperlipidemic diet group) or a regular chow diet (n=19, control group) for 15 wk. Then the animals were sacrificed and blood samples were collected for determination of plasma lipids, paraoxonase 1 (PON1), cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities, and lipids composition of the HDL fraction. Simultaneous transfer of phospholipids (PL), free cholesterol (FC), cholesteryl esters (CE) and triglycerides (TG) from an artificial lipidic nanoemulsion to HDL was performed in an in vitro assay, in which a nanoemulsion doubled labeled with either 14C-FC and 3H-TG or 14C-PL and 3H-CE was incubated with plasma and the radioactivity was counted in the HDL fraction after chemical precipitation. The aorta and the liver of the hamsters were collected for determination of the lipids composition and histological analysis. Plasma total cholesterol, HDL-C, n-HDL-C, CE, FC and PL were greater in the hyperlipidemic diet group than in the control group. However, TG levels were similar between the groups. Compared with the control group, the hyperlipidemic diet group had higher FC and CE in the HDL plasma fraction. Also, the transfer rates of 14C-FC, 3H-TG, 14C-PL and 3H-CE, CETP and PLTP were greater in the hyperlipidemic diet group compared with control group. PON1 activity was equal in both groups. The content of FC in the aorta tissue was greater in hyperlipidemic diet group, but the internal and external diameters of the aorta were equal in both groups. In hyperlipidemic diet group, the content of CE, FC, PL and TG in the liver and the diameter of the hepatocytes were greater than that measured in control group. The hyperlipidemic diet, i.e., dietary cholesterol and saturated fat, in hamsters, alters the FC and CE composition of the HDL fraction and lead to a disturbance in the ability of HDL to receive lipids. And consequently, may alter the antiatherogenic properties of this lipoprotein.

Carbon nanotubes (CNTs) have been one of the most studied nanoparticles and incorporated into various consumer products. It has been reported that CNTs can enter groundwater systems by accidental or intentional release into the subsurface. As transport mechanisms of CNTs are not well understood, investigation on mobility of CNTs in the subsurface will be helpful to define disposal regulations of CNTs. The objective in this study is to investigate the effect of solution chemistry (pH and ionic strength) and physical factors (collector grain size and flow rate) on the transport of multi-walled carbon nanotubes (MWCNTs). One-dimensional convection-dispersion model incorporated with collector efficiency for cylindrical nanoparticles was used to simulate the transport of MWCNTs in porous media. It was observed that higher pH led to increase in mobility of MWCNTs. The critical point of ionic strength for MWCNTs getting mobilized was narrowed down in the range of 2 to 5 mM. It was observed that the finer porous media could retain more nanoparticles. The decrease in pore water velocity resulted in a clear retardation, lowered the hydrodynamic force acting on the particles and led to more retention.

Titanium dioxide nanoparticles are widely used in a variety of products, such as pigments, paints, paper, plastics, cosmetics, nano-fibers, food coloring and photovoltaic cells, and the industry is growing at anexponential rate. It is believed that by 2025, 2.5 million tons of nano-TiO2 will be manufactured annually. Thus far, there has been very little research in the environmental impact of nano-TiO2. There is a need to understand the fate and transport of nanoTiO2 to mitigate their effect on human health, the ecosystems and the environment in general. The aim of this study was to investigate the impact of pH, flow rate and ionic strength on the deposition of nano-TiO2 in a saturated porous media (sand). Nano-TiO2 formed aggregates in solutions that had a pH near the point of zero charge for TiO2, which is at approximately pH 6.2 for TiO2. The formed aggregates showed very little mobility due to site blocking in the pores of the sandy medium, whereas at pH 7.5, the solutions’ concentration was more stable than at pH 6.3 and more mobile up to 10 mM. Above 10 mM, a decrease in mobility, due to reduction in repulsive energy interaction between the medium and the nanoparticles could be observed. Flow rate had also a marked effect on the deposition, i.e., the slower the flow rate, the higher on deposition, because of an increase in attachment efficiency. To verify the experimental results, a finite element solution of the reactive transport equation in one dimension was used to compare the fit between observed and simulated results. The model was run in inverse mode, to determine unknown parameter values such as dispersivity and detachment rate. In general, it was possible to obtain a good fit to theexperimental BTCs. / Nanopartiklar av titaniumdioxid används allmänt i en mängd olika produkter, såsom pigment, färger,papper, plast, kosmetika, nanofibrer, matfärgläggning, och solceller. Branschen växer explosionsartat.Man tror att år 2025 kommer 2,5 miljoner ton nano-TiO2 tillverkas årligen. Hittills har väldigt lite forskning gjorts på området nano-TiO2. Det finns ett behov av att förstå transportprocesser och vad som händer med nanoTiO2 i miljön för att bla kunna mildra effekter av dessa partiklar på människors hälsa, ekologi och miljö. Syftet med denna studie var att undersöka effekten av pH, flöde och jonstyrka (IS) på transporten av nano - TiO2 i vattenmättade porösa medier (sand). Nano - TiO2 bildade aggregat i lösningar som hade ett pH nära pH(PZC), pH(PZC) är pH-värdet vid vilket laddningen är noll, ungefär pH 6,2 för TiO2. Vid pH 6,3 visade nano partiklarna mycket liten rörlighet på grund av fysisk igentäppning i porerna av sandmediet, medan vid pH 7,5 var lösningens koncentration mer stabil och partiklarna mer mobila upp till en jonstyrka på 10 mM. Över 10 mM, observerades en minskning i rörlighet, på grund av minskad repellerande energi mellan mediet och nano partiklarna.Flödeshastighet hade också en markant inverkan på retentionen av partiklar i kolonnen, ju långsammare flöde, desto större retention, på grund av mer gynnsamma förhållande för fastläggning av partiklar till mediet. För att verifiera de experimentella resultaten och jämföra observerade och simulerade resultat användes en lösning med finita-elementmetoden av den reaktiva transportekvationen i en dimension. Inversmodellering gjordes för att ta reda på okända parametervärden såsom dispersivitet och fastläggning. Det var i allmänhet möjligt att uppnå god överensstämmelse mellan observerade ochexperimentella genombrottskurvor.