Dissertations / Theses on the topic 'Hydration fluid'

Adequate fluid consumption is central to human survival. Previous literature suggests that there some misconceptions regarding hydration and fluid balance in some populations. Available data also show that the role of thirst sensations in maintaining fluid balance in different settings is also equivocal. Therefore, this thesis aimed to examine the perception of hydration, thirst and fluid intake in freeliving populations, to examine the feasibility of thirst as a marker of hydration status and to investigate the effect of thirst related sensations on fluid balance in resting and exercising individuals under different ambient temperatures. The findings in this thesis (Chapter 3) show that individuals who work within the fitness industry demonstrated substantial knowledge about drinking practices, hydration status and health consequences of water consumption, but lack understanding on the type of beverages that adequately hydrate the body. Further, thirst perception and mood states did not affect (P>0.05) the fluid intake in free living individuals (Chapter 4) and resting individuals under cool and warm exposure (Chapter 6), but some other factors such as subjective feelings of mouth dryness and the extent of hydration status might influence the fluid intake behaviour in these populations. In addition, following ingestion of flavoured carbohydrate drinks, thirst sensations was rated lower over time (P<0.05) during exercise in the cool, but was higher over time in the warm temperature (Chapter 7). Moreover, subjective feelings related to dehydration such as mouth dryness, thirst perception, desire to drink (water pleasantness) and hunger rating could be used as index of hydration status to signify at least a 1% body mass loss due to food and fluid restriction in resting individuals (Chapter 5). In conclusion, the findings in this thesis provide some new insight with respect to hydration, thirst and fluid balance in different populations under different settings. Nevertheless, some inconclusive findings regarding the role of thirst related sensations in fluid balance require further investigations.

The thesis reports on 6 studies (2 of which were part of a multi-centre trial) examining hydration and fluid balance. The first study described in this thesis investigated the impact of hydration status on Dual energy x-ray absorptiometry (DXA) and other methods that are popular tools to determine body composition in athletes. We observed that it is important to ensure a euhydration when assessing body composition, particularly when considering changes associated with nutritional or exercise interventions. The second and third studies reported identified beverages that promote longer term fluid retention and maintenance of fluid balance in adults. We investigated the effects of 13 different commonly consumed drinks on urine output and fluid balance when ingested in a euhydrated state, with a view to establishing a beverage hydration index (BHI), i.e., the volume of urine produced after drinking expressed relative to a standard treatment (still water) for each beverage. The beverages with the highest BHI were oral rehydration solution, full fat milk and skimmed milk. BHI may be a useful measure to identify the short term hydration potential of different beverages when ingested in a euhydrated state. The fourth study aimed to systematically examine the influence of carbohydrate, sodium and caffeine content of beverages on the BHI. The BHI was greater in beverages with higher carbohydrate or higher sodium content, but not influenced by caffeine. The carbohydrate content of beverages has no effect on BHI at concentration up to 10% carbohydrate. Sodium content of beverages in concentrations of 27mmol/L and higher can improve the hydration potential of beverages. Caffeine doses in beverages up to 400mg/L do not have an impact upon diuresis when ingested in a euhydrated state. The fifth study compared net fluid balance (NFB) responses to the ingestion of commonly consumed drinks in young and older men. We observed that in young adults milk helps to maintain positive net fluid balance for longer than other drinks. In older adults this effect of milk is not observed despite similar net electrolyte balance responses. Future work should more fully explore these potential differences in fluid balance responses to drink ingestion between young and older adults. The final study investigated the hydration habits of Scottish young and older adults (+50 years old), identifying their fluid choices, volume, and preferences in relation to time of day. The results showed that 26.1% of the young females, 30.3% of the young males, 25.8% of the older females and 50.4% of the older males did not meet the European (EU) Food Safety Authority (EFSA) fluid intake recommendations. We also observed that the difference between those who met and those who did not meet the EFSA adequate intake could be attributed to differences in water ingestion, mainly during the mid-morning (after breakfast until 11 am) and during the early-afternoon (after lunch time up to 5 pm). It was concluded that these moments might be key when implementing interventions to improve hydration status especially in the older population.

Dehydration can impact the general population but it is particularly detrimental for athletes, due to their physical performance requirements. Although fluids in general contribute to meeting hydration needs, some beverages aid in the rehydration process more than others. The Beverage Intake Questionnaire (BEVQ-15) is a food frequency questionnaire (FFQ) that can rapidly assess habitual beverage intake; this FFQ has been validated in children and adults. However, no beverage consumption questionnaire has been validated in athletes. In addition to monitoring fluid intake, hydration status can be assessed through urinary and blood indices. Urine color (UC) has been utilized as a practical hydration biomarker in several populations. However, this biomarker has not been validated among the general population of collegiate athletes. The first study (n=58): formulated a novel whey-permeate-based beverage to promote hydration and assess its sensory characteristics in the general population. The overall acceptability of the beverage was lower than the control beverage, according to a 9-point Likert scale (x̅ = 4.5 – 4.9 and x̅ = 6.7, respectively). The second study (n=120): evaluated the comparative validity and reliability of the BEVQ-15 and UC within NCAA Division 1 collegiate athletes. Associations were noted between the BEVQ-15 and multiple 24-hr dietary recalls (reference method) for total beverage fl oz and kcal (r=0.41 and r=0.47, p<0.05, respectively). There were associations between athlete's UC and urinary specific gravity (USG; hydration biomarker) rated by athletes and researchers (r=0.67 and 0.88, p<0.05, respectively). Lastly, a systematic review was performed to evaluate original research addressing the validity of UC as a hydration biomarker in the adult population more broadly, including athletes and older adults. Eleven of 424 articles met inclusion criteria, and the available research generally reported significant correlations between UC and other hydration indices (r=0.35-0.93). However, limitations in existing research were evident. Although the BEVQ-15 may be a valid beverage intake assessment method in collegiate athletes, additional modifications were identified which could improve its validity. Future work includes re-evaluating the validity and reliability of the BEVQ-15 specifically modified for athletes, as well as assessing the sensitivity of this FFQ to detect changes in beverage intake.
Doctor of Philosophy
Drinking adequate amounts of fluids is important for maintaining normal bodily functions. When body water losses exceed fluid intake, dehydration may result, which can lead to numerous consequences such as headaches, dizziness, decreased mental focus, and fatigue. An athlete, who has high physical demands, may experience these negative consequences as well as muscle cramps, increased strain on the heart, and decreased athletic performance. Some beverages can replenish lost fluids better than others, due to their electrolyte (i.e. sodium, potassium, magnesium) content. This may include whey-permeate based beverages. In order to prevent dehydration, it is important to monitor fluid consumption and fluid losses. A beverage intake questionnaire (BEVQ-15) can be used to quickly assess usual beverage intake. Studies have shown that this questionnaire is accurate in children, adolescents, and adults. However, there are currently no validated methods for usual habitual beverage intake in athletes. This dissertation evaluated the taste of a new whey-permeate hydration beverage, and the accuracy and test-retest reliability of the BEVQ-15 within NCAA Division 1 collegiate athletes and found positive results. Measurements in urine and blood can be also be used to assess hydration status, but some of these methods are more expensive and less practical for daily use in real-world settings. Urine color (UC) has been studied as a hydration indicator, but this dissertation is the first to evaluate the accuracy and reliability of this method within a diverse group of collegiate athletes, in a real-world setting. Our results suggest that UC is a simple and reasonably accurate hydration assessment method when compared to another urinary assessment method. Nonetheless, there is limited research which has studied this topic. Future work can address methods to improve the effectiveness of these approaches for maintaining and evaluating fluid intake and status in the collegiate athletic population.

Motorsport is a physically and cognitively demanding sport, where driver-athletes compete in compensable environments. The term ‘driver-athlete’ acknowledges that drivers possess certain unique skills that have been developed through training and practice that allows them to compete for a prize, recognition and admiration from peers and the public. Hydration and physical fitness are two important variables that may assist in a driver’s preparation for a race and subsequent health, safety and performance. This thesis has three main research studies that aim to understand the associated demands of motor racing, the attitudes and behaviours of drivers towards thermoregulation and physical fitness and finally understanding how these variables interact to determine the impact of dehydration on a driver’s health, safety and performance. The studies collectively contributed to better understand how to optimise the performance of the driver-athlete. Study one aimed to explore the hydration status and thermoregulatory responses during Australian Supercar racing. Data was collected from Friday through to Sunday of three separate race meetings from three professional Australian Supercar drivers. Friday races consisted of three 20 – 30 min practice sessions, Saturday was a 20 min qualifying session and two races (36 – 56 min) with one endurance race (75 – 116 min) on Sunday. Contrary to our hypothesis, drivers progressively hydrated over the three days in accordance with a gradual increase in fluid intake, despite rarely consuming fluid during a race due to unpalatable water temperatures and limited availability of fluid. Morning urine samples indicated a hypohydrated [urine specific gravity (USG) >1.020] state for 50, 44 and 44% of the samples collected on Friday (n = 6), Saturday (n = 9) and Sunday (n = 9), respectively. Importantly, 25% (n = 16) of tympanic temperatures were >38.5oC indicating moderate heat strain and moderate-to-extreme dehydration [42% of total samples (n = 158) with a USG >1.020], suggesting that some drivers may be susceptible to hyperthermia and dehydration in compensable environments. Study two determined if the observed behaviours in study one were related to the attitudes of drivers towards hydration, and whether those behaviours were a construct of their purported benefit/decrement on performance. Using a survey that was divided into three components: 1) attitudes and perceptions, 2) behaviours, and 3) demographics was completed. The survey included a total of 79 questions on a Likert-type scale rating importance or agreeance, and in some questions, acknowledgement of select behaviours. A total of one hundred drivers (56.5% of respondents) completed the survey in full. Driver-athletes noted the importance of fluid balance (95.0% of respondents) and physical fitness (80.0% of respondents) in relation to performance. A higher (p = 0.002) number of professional drivers (71.4%) noted the importance of measuring body mass for hydration status compared to amateur drivers (37.5%). A higher (p = 0.008) percentage of amateur drivers (70.8%) indicated that they don’t follow an individualised hydration plan in comparison to professional drivers (42.9%). External cooling devices were used across a race weekend, including cool suits and cold towels (both 16.0%), and ice vests and ice baths (4.0%). Plain water was predominately ingested (95.0%) across a race weekend by drivers, however there was a distinct lack of access to fluids during a race. There was an apparent lack of translation from attitudes to behaviours for idealistic hydration, thermoregulation and physical fitness-related practices. Drivers clearly acknowledge the importance of hydration, thermoregulation and physical fitness, but the importance placed on measuring these factors to prevent dehydration and heat stress is not evident. The preceding studies informed the methodological design for research study three. In this study, the effect of dehydration on simulated motor racing performance and physiological parameters were investigated. In a crossover-control design, participants (n = 15) were randomised (counter-balanced) to either a no fluid trial [2.00% body mass loss (BML)] or fluid trial to achieve a 0.50% body mass gain. Passive dehydration to 2.00% BML was achieved via sauna exposure (43.3°C). The control group was also exposed to the sauna, however received plain room temperature water in 9.5 ± 1.5 bottles of water every 10 min to achieve a 0.50% body mass gain. After a 2 h rest period participants raced around the Bathurst race-track using a fixed-based racing simulator for 60 min in conditions (43.2°C) similar to that of Australian Supercar racing. Dehydration appeared to have no influence (p = 0.293) on racing performance, however, there was a trend (p = 0.007; r = 0.516) for drivers to have more severe errors towards the end of the race. There was a positive (p < 0.05) effect of being hydrated on peak measurements of core temperature (37.7 ± 0.3 vs. 38.0 ± 0.2°C), physiological strain index (3.5 ± 1.1 vs. 4.1 ± 1.1) and heart rate (121 ± 16 vs. 129 ± 16 beats.min-1) in comparison to being dehydrated. This data indicates that entering a race of 60 min duration in a dehydrated state (2.69% body mass loss) resulted in no performance benefit or detriment, despite participants reporting feelings of thirst and reduced alertness, concentration, and mood at the beginning of the race. Overall, this thesis shows that hydration does have a role in a driver’s health, safety and performance. However, the importance and hierarchical priority of hydration in a driver’s preparation is highly individual with substantial variations in thermoregulatory responses to motor racing. It appears the hydration behaviours and attitudes of drivers have limited impact on their racing performance, however, may have effects on their health and thermoregulatory capacity. Collectively, the present results provide insight into the driver-athlete and the role that hydration has on a driver's health, safety and performance.

Systemic hydration, plasma electrolytes, ingesta and fecal hydration and gastrointestinal passage of cobalt (after CoEDTA administration via nasogastric tube) in horses fed large grain meals or treated with enteral fluid therapy, IV fluid therapy and enteral laxatives were investigated. In the first study, 0.9% NaCl (10 L/h/8h) was administered slowly via a small-bore nasogastric tube or as 10 L boluses via a large-bore nasogastric tube to four normal horses. In the other studies, horses with a right dorsal colon fistula were used. To create the right dorsal colon fistula, a cannula with 5 cm internal diameter was implanted 2 to 6 weeks after a right dorsal colopexy had been created. Six horses with the right dorsal colostomy were alternately used to test three feeding regimes for 48 h: 1- hay free choice; 2- hay free choice plus 4.5 kg of sweet feed twice daily after a period of 5 days of adaptation; 3- sudden change from hay to hay plus sweet feed. Seven horses with the right dorsal colostomy were alternately used to test 6 experimental conditions while fasted for 24 h: 1- control (no treatment), 2- enteral MgSO4 (1 g/kg), 3- enteral Na2SO4 (1 g/kg), 4- IV lactated Ringer's solution (5 L/h/12 h), 5- enteral water (5 L/h/12 h), 6- enteral electrolyte solution (5 L/h/12 h). In the last study, four horses with the right dorsal colostomy were alternately treated with enteral electrolyte solution (10 L/h/6h) and enteral MgSO4 (1 g/kg) plus IV fluid therapy (10 L/h/6h). Despite the administration regimen, enteral administration of 0.9% NaCl produced diarrhea, hypernatremia and hyperchloremia. Colostomy allowed serial collection of large ingesta samples. Grain ingestion did not change PCV or plasma protein, but affected plasma electrolytes and produced dehydration of ingesta and formation of frothy ingesta. Fasting delayed gastrointestinal transit. Enteral fluid therapy was the most effective treatment in promoting ingesta hydration. Enteral water, MgSO4, Na2SO4, IV fluid therapy and enteral MgSO4 plus IV fluid therapy were either ineffective in promoting ingesta hydration or produced marked plasma electrolyte imbalance. These findings support the use of enteral fluid therapy in horses with gastrointestinal impaction.
Ph. D.

Utilising a survey based approach, this thesis aimed to understand how fluid intake practices differ among endurance runners and characterise how fluid practices may reflect performance outcomes. The findings from this study indicate that collectively there is no difference between sex when exploring fluid intake beliefs and behaviours towards hydration optimisation strategies. This suggests that human behaviour is influential in understanding fluid intake practices in endurance runners. Fluid intake optimisation strategies are highly individualised and further research is still required to shape the avenue for future fluid intake recommendations.

During exercise water and electrolytes are lost in sweat. There is a large variation in both sweat rate and sweat composition and as a consequence sweat electrolyte loss can be large, especially for sodium, the primary cation in sweat. The loss of large amounts of sodium in sweat has been linked with hyponatraemia and muscle cramps. Sodium intake is encouraged in some athletes and in some exercise situations, which is in direct contrast to guidelines aimed at the general population aimed at reducing average sodium intakes to 2.4g of sodium per day (6g salt/day). Dietary sodium intakes have been determined by numerous methods, including weighed dietary records and 24h urine collections. As dietary sodium intake in excess of basal requirement is primarily excreted in the urine in non-sweating individuals, and the basal requirement for sodium is small, 24h urine collections can provide an accurate estimate of dietary sodium intake. In Chapter 3, 24h urinary sodium excretion was measured in eighteen subjects on 4 separate occasions. Subjects consumed their normal diet with the exception of a 5g creatine supplement and 500ml of water, which was part of a separate investigation. The relationship between urine sodium excretion in each 24h collection period was weak, but on average males excreted 200 ± 48mmol of sodium per day and females excreted 157 ± 33mmol of sodium per day, which is equivalent to 4.6g and 3.6g of sodium, respectively. This is in excess of the current recommended intake. In chapter 4, the variation in sodium excretion was determined in eight subjects who consumed the same diet for 5 consecutive days. Despite the similar intake of sodium each day, a day to day variation in sodium excretion of 13% was still observed. This was not related to either sodium intake or potassium intake. In chapter 5, nine subjects consumed their normal diet for 5 consecutive days but weighed and recorded all food and drink consumed. During this period, 24h urine samples were also collected. No strenuous exercise was permitted apart from an exercise task on day 4. This involved intermittent cycling in the heat until 2% body mass (BM) was lost. Sweat was collected from four absorbent patches placed on the back, chest, forearm and thigh. Sweat sodium concentration was adjusted to account for the 35% over-estimation using this regional collection method. Subjects lost 1.51 ± 0.19L of sweat and 66 ± 16mmol (range 32 86mmol) of sodium. There was no difference in sodium balance between each 24h period due to a significant decrease in urine sodium excretion on the day of exercise (day 4). In chapter 6, the effect of prior exercise on sweat composition during a second exercise bout completed later that same day was determined. Eight healthy males cycled for 40 minutes in the heat on one or two occasions. A period of 5h elapsed between exercise bouts when two exercise sessions were performed. Sweat was collected using a whole body washdown method and by 4 absorbent patches placed on the back, chest, forearm and thigh. The main finding was that prior exercise did not affect sweat rate or sweat sodium, potassium and chloride concentrations in the second exercise bout when using the whole body washdown method. Chapter 7 determined the effects of two exercise sessions completed on the same day on electrolyte balance. Nine subjects followed their normal dietary behaviour but weighed and recorded all food and drink consumed during 5 consecutive days. During this period 24h urine samples were also collected. No strenuous exercise was permitted during this period apart from two exercise tasks on day 4. During exercise sweat was collected using a whole body washdown technique. Sweat rate and sweat sodium, potassium and chloride concentrations during the second exercise bout were found to be similar to the first exercise bout. Subjects lost 2.64L (range 1.80 3.48L) of sweat and 138 ± 106mmol of sodium (range 32 287mmol). Sodium balance was not significantly affected on the day of exercise, but urine sodium was lower than dietary sodium intake on the day of exercise (Day 4) and the day following exercise (day 5), indicating significant sodium conservation by the kidney. In contrast, no change in sodium intake was observed. In chapter 8, the effect of skimmed milk and a sports drink in restoring fluid balance was examined following exercise-induced dehydration. Seven physically active males cycled intermittently in the heat until 2% BM was lost. During a 1h rehydration period a sports drink (23mmol Na+/L) or skimmed milk (32mmol Na+/L) was consumed in a volume equivalent to 150% of BM loss. Fluid balance at the end of the 3h recovery period tended to be more positive when milk was consumed. Despite this, no difference in exercise capacity in the heat was observed. This thesis shows that exercise did not increase sodium intake, but this may be due to the already high dietary sodium intake of individuals. Sodium balance was maintained in the majority of individuals due to a significant conservation of sodium by the kidneys. When sweat sodium losses are large, urine sodium conservation may not be sufficient to prevent a negative sodium balance. When no food is consumed in the acute period post-exercise, the higher sodium content of skimmed milk than a sports drink may be partly responsible for the increased retention of the ingested fluid. But this did not enhance subsequent performance in the heat.

The project investigates the dietary factors that influence a person’s hydration status, primarily by measuring body water turnover. Body water turnover is commonly reported as a marker of hydration status for its measurement of total fluid gains and losses over a 24-hour period and can be particularly useful in predicting (and hence managing) fluid loss in individuals experiencing large losses. The study found that active individuals have faster water turnovers, explained by the larger water volumes they consume but also their overall fibre intake. This research has important implications for the impact of dehydration on physical and/or cognitive declines.

The main goal of this diploma thesis is to determine the role of hyaluron acid and phospholipids on friction and lubrication of articular cartilage in regard to optimization of viscosupplements. This is carried out by measuring the coefficient of friction of the articular cartilage with several lubricants. Cartilage is lubricated particularly by a conventional viscosuplement, optimized viscosuplementation with phospholipids and model synovial fluid. In order to observe the function of those viscosuplements in the human body, both are mixed with the model synovial fluid, ubiquitous in human joints, in given ratio. Experiments revealed high friction when it comes to convectional viscosupplementation as opposed to low friction of the optimized viscosuplement with phospholipids. The same situation occurs when cartilage is lubricated with those viscosuplements mixed with model synovial fluid which might lead to development of a new, better, viscosupplementation based on hyaluron acid and phospholipids.

La vitesse à laquelle le monde actuel fonctionne a des répercutions directes sur tout ce qui nous entoure et, en premier plan, sur le marché de la construction dont les cirières sont de plus en plus exigeants tels que les courts délais de construction, la complexité des formes, etc. L’utilisation des bétons fluides dont les propriétés rhéologiques sont bien maîtrisées est une clé pour satisfaire à ces critères, d’autant plus qu’on se trouve au seuil d’une nouvelle ère dans le monde de la construction incluant l’impression 3D des bétons. Cependant, une sélection adéquate des ajouts minéraux (AM) et des adjuvants chimiques (superplastifiants, SP et agents de viscosité, AV) qui entrent dans la conception des bétons fluides s’avère un problème crucial. Un programme expérimental très étendu est mené pour mettre la lumière sur l’effet de huit différents AM dans des systèmes binaires et ternaires ainsi que l’effet de leurs interactions avec les adjuvants chimiques (SP et AV) sur les propriétés des mortiers de bétons équivalents (MBE). Deux classes de bétons fluides sont visées dans cette étude comprenant les bétons autoplaçants (BAP) pour la construction des bâtiments et les bétons semi-fluides (BSF) pour les infrastructures de transport. Une attention particulière est portée sur les propriétés rhéologiques, sans pour autant négliger la chaleur d’hydratation ainsi que les propriétés mécaniques. Les résultats ont montré qu’il est difficile de faire une généralisation sur l’influence des AM sur les propriétés des MBE. Les propriétés physiques des AM telles que la finesse, la forme ou encore la granulométrie des particules sont des facteurs qui jouent un rôle important dans la rhéologie des bétons fluides. Cependant, l’influence de ces facteurs peut être masquée par l’interaction physique et chimique qui peut avoir lieu entre les poudres et les adjuvants chimiques utilisés (type de SP en présence de ou sans AV compatibles). La morphologie des particules des AM a un effet direct sur la viscosité plastique des MBE. Une forme angulaire et irrégulière (facteur de Ferret autour de 0,4), contribue à augmenter la viscosité plastique des MBE et une forme sphérique (facteur de Ferret proche de 1) contribue à diminuer leur viscosité plastique. Par ailleurs, les résultats de l’analyse statistique ont montré que l’influence des AM en combinaison ternaire (une poudre à faible réactivité avec une poudre à réactivité élevée), en présence d’un rapport eau/poudres (E/P) relativement élevé (0,45), sur la majorité des réponses n’est que la somme des effets individuels de ces poudres. Par contre, un effet d’interaction entre les poudres pour certaines réponses a commencé légèrement à prendre place lorsque le rapport E/P est diminué à 0,41. Cependant, dans le développement des résistances à la compression à 28 et 91 jours, les poudres à réactivité élevée comme la fumée de silice ou le métakaolin avaient généralement une contribution positive plus importante que celle des poudres à faible réactivité. Les résultats de l’hydratation des MBE ternaires, suivie par la calorimétrie isotherme, n’ont pas montré l’effet synergétique escompté de la combinaison d’une poudre à faible réactivité avec une autre à réactivité élevée dû à l’augmentation de la demande en SP en présence de cette dernière. Une optimisation multiparamétrique a permis de sélectionner des ciments ternaires servis au développement des bétons écologiques présentant les meilleures performances. Finalement, l’utilité de la méthode des MBE dans la prédiction de l’effet des AM sur les bétons a été discutée.
Abstract : The speed with which the world operates today has direct repercussions on everything around us and, in the foreground, on the construction market, where the criteria are more and more demanding such as short construction times, complexity of forms, etc. The use of fluid concretes where rheological properties are well controlled is a key to satisfy these criteria, especially since we are on the threshold of a new era in the construction world including the 3D concrete printing. However, an adequate selection of mineral additives (MA) and chemical admixtures (superplasticizers, SP and viscosity agents, VA) that are used in the design of fluid concretes is a crucial problem. A very extensive experimental program is conducted to shed light on the effect of eight different MA in binary and ternary systems as well as the effect of their interactions with the chemical admixtures (SP and VA) on the properties of concrete equivalent mortars (CEM). Two classes of fluid concretes are investigated in this study, including self-consolidating concrete (SCC) for building constructions and semi-flowable concrete (SFC) for transportation infrastructures. Particular attention is paid to the rheological properties, without neglecting the heat of hydration as well as the mechanical properties. The results showed that it is difficult to generalize on the influence of MA on the properties of CEM. The physical properties of MAs such as fineness, shape or particle size distribution are factors that play an important role in the rheology of fluid concretes. However, the influence of these factors can be masked by the physical and chemical interaction that may occur between the powders and the chemical admixtures used (type of SP in the presence or not of a compatible VA). The particle morphology of MA has a direct effect on the plastic viscosity of CEM. An angular and irregular shape (Ferret factor around 0.4) contributes to increase the plastic viscosity of CEM and a spherical shape (Ferret factor close to 1) contributes to decrease their plastic viscosity. Moreover, the results of the statistical analysis showed that the influence of MA in ternary combination (low-reactivity powder with high-reactivity powder), in the presence of a relatively high water-to-powder ratio (W/P) of 0.45, on the majority of responses is only the sum of the individual effects of these powders. On the other hand, an interaction effect between the powders for some responses began slightly when the W/P was decreased to 0.41. However, in developing 28- and 91-day compressive strengths, high-reactivity powders such as silica fume or metakaolin generally had positive contribution higher than low-reactivity powders. Results of ternary CEM hydration followed by isothermal calorimetry did not show the expected synergistic effect of combining a low-reactivity powder with another with high reactivity due to increased demand in SP in the presence of the latter. A multiparametric optimization allowed selection of ternary cements used to develop ecological concretes with the best performance. Finally, the use of the CEM method in prediction of the effect of AM on concrete was discussed.

Ce travail etudie les systemes pouzzolanes naturelles-chaux-eau a 38 et 100c afin de comprendre les phenomenes physicochimiques caracterisant la pouzzolanicite des materiaux naturels. La mise en evidence de nouveaux criteres physicochimiques correlant la mineralogie des produits d'hydratation, les qualites mecaniques des melanges pouzzolanes-chaux-eau nous permet de proposer une nouvelle classification des materiaux pouzzolaniques. Cette classification repose sur: une caracterisation et une quantification des constituants reactifs (les verres volcaniques non rhyolitiques, les opales, les zeolites), une etude des solides neoformes et des solutions issus de l'essai chapelle (16 h a 100c dans une solution saturee de chaux), une etude mineralogique et morphologique des phases cristallines neoformees, issues du systeme pouzzolanes-chaux-eau a 38, constituant la matrice des pates durcies. L'ensemble de ces observations montre que les silices sedimentaires, les roches volcaniques et l'alumine activee constituent une serie homologue discontinue a 38 et 100c dans le systeme cao-sio2-al203-h20. Ces materiaux s'illustrent par la coexistence entre la fraction siliceuse de la solution solide des hydrogrenats et des gels silicocalciques hydrates (partiellement alumineux) a 100c et la coexistence entre la solution solide des silicoaluminates tetracalciques hydrates et les gels silicocalciques hydrates

Brillouin spectroscopy probes the thermally generated pressure fluctuations (sound waves) which propagate in a material. The resulting information on sound velocity and absorption provides a fast and efficient method of monitoring high frequency (GHz) dynamics in the system being studied. In certain cases, structural information may also be inferred from changes in the Brillouin spectrum as a function of temperature, pressure or composition (in the case of multi-component systems). The aim of the work presented in this thesis was to integrate Brillouin spectroscopy into current soft condensed matter research projects at Edinburgh, namely (i) hydration in methanol-water mixtures and (ii) the behaviour of hard-sphere colloidal dispersions. A Brillouin spectrometer based on a Fabry-Perot interferometer was developed and tested, resulting in a high-resolution instrument operating at variable scattering vector (exchanged momentum), temperature and pressure. The technical aspects of this work were carried out in collaboration with a colleague. Data analysis routines were designed and implemented, enabling calibrated Brillouin spectra to be produced automatically from raw experimental data. Excellent agreement with results on several materials studied in the literature confirmed the accuracy and sensitivity of the spectrometer. The molecular details of hydration in methanol-water mixtures are of great interest due to the prototypical amphiphilic nature of the methanol molecule. The effect of deep cooling on the Brillouin spectrum across a wide range of methanol concentrations was studied in detail, resulting in the first observation of an anomalous increase in sound velocity and maximum in sound absorption at intermediate compositions. A similar effect was then found at higher temperature in aqueous tertiary butanol, and was identified in a brief survey of several other aqueous solutions. High pressure Brillouin spectra indicate that this anomalous behaviour may also be present in pure water. It is suggested that these novel effects may be due to the presence of a relatively unperturbed water structure in the aqueous solutions studied, even at quite high solute concentration. Preliminary results from a neutron diffraction experiment performed on a 40% by mass methanol-water mixture were consistent with this hypothesis. Brillouin spectroscopy was also used to study the propagation of high frequency sound in monodisperse colloidal suspensions of sub-micron hard spheres. A second longitudinal sound mode was observed for scattering vectors of magnitude greater than pi/d where d is the diameter of the spheres. These results are the first reproduction and extension of the pioneering work in the field, which identified the additional mode with a surface acoustic excitation, propagating between adjacent spheres via an evanescent wave in the solvent. The new results show that the second mode is extinguished at a particular scattering vector - an effect not reported previously. It is suggested that this extinction is due to the minimum in the form factor for elastic scattering from a single sphere.

Title: Ultrasound measurements on the inferior vena cava (IVC-US) by renal nursing staff for assessment and management of intravascular volume status in haemodialysis patients. Aims: The primary aim of this thesis was to provide evidence that renal nurses could safely and efficiently perform IVC-US on haemodialysis patients to obtain objective assessment of intravascular volume status and potentially reduce adverse events and morbidity. The secondary aims for this study were: (1) conduct a systematic literature review to identify evidence if renal nurses have previously used this method for intravascular volume assessment; (2) teach a renal nurse through a staged educational programme, guided by a medically trained ultrasonographer, a sonologist, to gain competency in ultrasound image acquisition and interpretation of the scans; (3) measure the prevalence of any form of intradialytic hypotension in a satellite haemodialysis clinic over a three-month period and (4) attain concurrent IVC-US and bioimpedance spectroscopy measurements on 30 patients during their haemodialysis treatment and to compare these findings with their intravascular volume status using the traditional clinical nursing assessment method. Materials and Methods: To achieve this primary aim, this thesis was separated into multiple phases. First, a systematic literature review of medical and nursing databases was performed to summarise the use of IVC-US in haemodialysis patients by renal nurses. The second phase involved a retrospective data analysis, where the prevalence rate of nurse-documented fluid related intradialytic hypotensive events was measured and a Generalised Estimating Equation (GEE) model was used to predict the likelihood of any form of intradialytic hypotension or postdialytic overhydration. In the next phase a four-step educational programme was developed in collaboration with an expert sonologist, guiding the renal nurse through the process of skill acquisition and accurate fluid assessment based on nurse-performed IVC-US scans. Following this phase, and after receiving theoretical training and performing 100 proctored scans, the renal nurse then performed 60 IVC-US scans independently, which were subsequently assessed by two sonologists, resulting in a cross-sectional interrater study, confirming competency. The final phase of the thesis consisted of a simulative pilot study, where 30 haemodialysis patients were assessed during three intradialytic moments of a single session on their intravascular volume status with IVC-US. Results: The systematic literature review revealed that there is a paucity of knowledge regarding renal nurses and IVC-US. The 3-month data analysis has shown that intradialytic hypotension (IDH) was still the most common adverse intradialytic event with 13.1% of all treatments affected. The renal nurse mastered the educational programme and was deemed competent by the experts. Finally, the simulative pilot study revealed that if IVC-US had been performed and indicated intravascular hypovolemia, patients had a 14-fold chance to experience subsequent IDH events. An algorithm using IVC-US combined with bioimpedance spectroscopy (BIS) and mean arterial pressure (MAP) revealed a sensitivity of 95% and a specificity of 100% for the prevention of IDH. Conclusions: This thesis demonstrates the obvious need for more objective and reliable fluid assessment methods in the haemodialysis population to improve clinical outcomes. Most importantly, it has been shown that renal nurses can master the skill to perform IVC-US and that IVC-US is a useful and reliable method of fluid assessment. Performing IVC-US is a transferrable skill and has potential to be preventative for intradialytic hypotension if added to the clinical fluid assessment routine by renal nurses. It has potential to change clinical practice and policy in future, but further research studies are needed to provide evidence for this.

This thesis details novel analysis methods that were applied to investigate shale and clay mineral reactivity as they come in contact with water-based drilling fluids. Six commercial additives were tested and their shale stabilizing potential was investigated through the use of two advanced particle analyzers – FBRM M500 and Malvern Mastersizer 3000. The experimental study and subsequent results indicate that these novel tools can indeed be used to analyze shale hydration and dispersion through particle analysis.

В дисертації досліджено характер й умови передачі тиску через стовп тампонажного розчину в процесі його тужавіння. Встановлено зв’язок між величиною переданого тиску і міцністю каменю на стискування. Визначені критичні значення міцності цементного каменю на стиснення, при яких починається зниження і припинення передачі тиску. Удосконалено технологію цементування та розроблено методику підбору рецептур для попередження заколонних ГНВП на початковій стадії тужавіння цементного розчину. Для зниження проникності цементного каменю на початковій стадії тужавіння рекомендується зв’язувати надлишок води замішування і надавати йому початкового напруження зсуву кремнійорганічними сполуками з ряду силанів - АКОР. Показано позитивний спектр властивостей тампонажних розчинів і утвореного цементного каменю з домішками АКОР. На основі результатів виконаних досліджень розроблені проекти керівних нормативних документів з кріплення свердловин для бурових підприємств Департаменту геології та використання надр й ДК ’’Укргазвидобування”. Рекомендації з удосконалення технології цементування свердловин впроваджені у виробництво.
На основании анализа теоретических, экспериментальных и практических работ выделено основные причины возникновения миграции пластовых флюидов на начальном этапе формирования тампонажного камня главными этих причин следует считать появление движущей силы, которая возникает при уменьшении гидростатического давления столба там понажного расствора и образовании суффозионных каналов миграции пластовых флюидов. При исследовании характера и условий передачи гидростатического давления через столб тампонажного раствора в процессе его твердения установлено, что причиной передачи давления является фильтрация флюида через пористую среду с продуктов гидратации цемента, а её прекращение связано с процессами зарастания поровых каналов. Показано, что существующая на сегодняшний день рекомендация, согласно которой конец схватывания в нижней порция тампонажного раствора должен наступать не позднее двух часов до начала схватывания верхней порции, справедлива только для портландцементных растворов. Для специальных цементов и тампонажных растворов с добавкой замедлителя сроков схватывания эта рекомендация неприемлема. Установлено наличие связи между величиной передаваемого давления и прочностью камня на сжати е независимо от типа вяжущего, наличия и вида добавок регуляторов срока схватывания тампонажного раствора и других факторов. Устанавлены критические значения границ прочности камня на сжатие, при которых начинается снижение коэфициента передачи и полностью прекращается передача давления, которые соответственно составляют 0,56 i 1,42 МПа. Тампонажные растворы, граница прочности камня которых на сжатие не превышает 1,42 МПа, не обеспечивают герметичности цементного камня, а их использование может стать причиной возн икновения заколоннс й миграции пластових флюидов. Усовершенствована технология разобщения продуктивных горизонтов, которая заключается в цементирование двумя порциями тампонажних растворов с разными темпами набора прочности камня. Нижняя порция (для интервала залягания продуктивного горизонта) должна достигать прочности,42 МПа, до того, как прочность верхней порции достигнет 0,56 МПа. Разработано методику подбора рецептур тампонажного раствора для конкретных горно-геологических условий ДДв. Предложено для снижения проницаемости цементного камня на начальных стадиях твердения связывать избыток воды затворения и придавать ей начальное напряжение сдвига кремнийорганическими соединениями типа АКОР. На основе теоретических и экспериментальных работ разработана методика и определены оптимальные концентрации АКОРбзоо» составляющие в зависимости от водоцементного соотношения Зн-6% массы вяжучего. Пористость цементного камня на начальной стадии твердения не зависит от типа вяжущего, водоцементного отношения и введённых химреагентов, а определяется только степенью его гидратации. Исследованы технологические свойства рецептур тампонажных растворов и полученного цементного камня з добавками АКОР. Добавка АКОРбзоо в состав тампонажного раствора улучшает его реологические параметры, повышает седиментационную устойчивость, понижает фильтрацию и не изменяет при этом сроков схватывания. АКОРбзоо существенно снижает проницаемость камня на начальной стадии твердения без ухудшения его прочностных характеристик. Экспериментальными исследованиями величины расширения при твердении цементно-зольных смесей с добавками АКОРвзоо установлено, что они являются безусадочными. Изучением влияния добавки АКОРбзоо на кинетику объемных изменений расширяющихся тампонажных растворов установлено, что она не уменьшает величины расширения. Коррозионная устойчивость цементно-зольных смесей с добавкой АКОРвзоо в агресивных солях сульфата и хлорида магния повышается. По результатам експерименгальных исследований показана целесообразность использования добавки АКОРбзоо при пластовых температурах 100-тТ30°С. Результаты проведённых научных исследований вошли в состав проектов руководящих нормативных документов по креплению скважин для буровых организаций Департамента геологии и использования недр, и ДК ’’Укргаздобыча”. Технологические рекомендации по усовершенствованию технологии цементирования скважин для повышения герметичности затрубного пространства в период ОЗЦ испытаны при цементировании скважин на предприятиях ГГГ1 ’’Полтаванафтегаз-геология” и ООО ’’Пласт”, ДП ’’Охтырканафтегаздобыча”, которые строятся на заказ ГГП ’’Полтаванафтегазгеология”. Во всех случаях получено удовлетворительное качество крепления. Заколонные перетоки отсутствуют.
The given thesis contains the study of the nature: and conditions for pressure transmission through the column of g routing mortar in the process of its setting. There has been fixed the relation between the value of the pressur transmitted and the rock compressive strength. Also there ha ve been defined the critical values of compression strength of cement rock, at which pressure transmission starts lowering and stops. Cementing tehnology has been improved, and methods of selecting formulae to prevent gas, oil and water manifestations at the initial stage of grouting mortar settihg have been developed. To lower the perméabilité of cement rock at the initial stage of setting, it has been suggested to add mixing water excesses and to dring them to the initial stress level of the displacement by AKOP - silicon organic compouds belonging to silanes. There have been described the positive properties of grouting mortars and of formed rock wint AKOP admixtures. The results of the inverstigation can be found in the nonnative documents on well grouting, sent winh the aim of implementation to the drilling enterprises that belong to the Departament of geology and mineral and natural resources use in Ukraine, and to ’’Ukrgazvydobuvannia” branch company. The recommendations at cementing tehnology are introduced in drilling Companys.

abstract: Water makes up about 45-70% of a human body's total weight. It is estimated that 80% of the human brain's tissue is composed of water. Cognitive productivity is altered when the body is in a mere 2% dehydrated state. Several cognitive functions impacted by dehydration include: visual motor tracing, short-term recall, attentiveness, and mathematic efficiency. It is estimated that 80% of the U.S. adult population endures the majority of their day in a mildly dehydrated state. Participants were employees working full-time jobs with Arizona State University or Tri Star Motor Company. Employees had to be 18 or older were invited to join the study. Employees participating in the study lived within the the greater Phoenix area. Participants of all races, genders, activity statuses, and BMIs were encouraged to join. A one-arm, pre-test, post-test study design was utilized. We examined whether the hydration status of participants in the intervention improved or worsened during the course of the intervention, and then attributed any such improvement or deterioration to the intervention. Urine collections from an afternoon sample were gathered before and after the one-week intervention. For the intervention, the participating offices received a water dispensing system in close proximity to employee desk spaces. A reusable water bottle was also given to each participant. Urine specific gravity (USG) was assessed in all urine samples to indicate hydration status, and all participants completed water intake surveys before and after the intervention. From this study, the overall change in water intake over the course of the one-week intervention was 143 ounces/day. This is an average of adding two and a half 8 oz glasses of water each day of the week per participant. USG also decreased significantly at the end of the intervention in comparison to the baseline value. In the greater body of research, this study strengthens the viability of inputting a hydration station and offering reusable water bottles to employees. This cost-effective method is an easy way to incorporate employee wellness in the workplace. The benefit of employees to drink more water is numerous, including increased focus, mental reactivity, and overall mood and wellness.
Dissertation/Thesis
Masters Thesis Nutrition 2018

Adolescent athletes of this era are more pressurized than adolescents of previous generations to perform at an optimum level (Micheli & Jenkins 2001, p49). The importance of winning can result in adolescent athletes developing inappropriate nutritional practices such as neglecting hydration and consuming insufficient carbohydrate (Micheli & Jenkins 2001, p57). Consuming insufficient fluid leads to dehydration which reduces a soccer player’s ability to continue training. Consuming inadequate carbohydrate reduces performance and blood glucose levels during training. This study aimed to determine the hydration status, fluid and carbohydrate intake of male, adolescent soccer players during training. A cross-sectional study was conducted among 122 amateur male, adolescent soccer players (mean age = 15.8 ± 0.8 years; mean BMI = 20.4 ± 2.0 kg/m2). The players’ hydration status before and after training, was measured using urine specific gravity and percent loss of body weight. Their carbohydrate intake, as well as the type and amount of fluid consumed, were assessed before, during and after training. A questionnaire was administered to determine the players’ knowledge regarding the importance of fluid and carbohydrate for soccer training. The study had an 87.1% response rate. The mean environmental conditions did not predispose players to heat illness. However, the players were at risk of developing heat illness during six of the 14 training sessions. Although the mean urine specific gravity indicated that players were slightly dehydrated before and after training, 43.8% of players were very or extremely dehydrated before training and 53.6% after training. A few (3.3%) were extremely hyperhydrated before training and after training (7.0%). On average players lost less than 1% of body weight during training and less than 3% of players dehydrated more than 2%. Players consumed mainly water before (289.17 ± 206.37 ml), during (183.20 ± 158.35 ml) and after (259.09 ± 192.29 ml) training. More than 90% stated that water was the most important fluid to consume before, during and after training. Very few (4.7%) correctly stated that carbohydrate should be consumed before, during and after training. Players were found to be slightly dehydrated before and after training and therefore were not consuming enough fluids during training. Players consumed inadequate amounts and types of fluid and carbohydrate. This not only compromises their performance but also health. Players were not aware of the importance of fluid and carbohydrate for soccer training. This study is unique in that it focused on the carbohydrate and hydration practices of socioeconomically disadvantaged adolescent soccer players during training. The study sample therefore represents a high risk group about which there is limited published data both locally and internationally. This study generated important baseline information which was lacking before on the hydration status, fluid and carbohydrate intake of adolescent soccer players in South Africa.
Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

abstract: Exposure to sun radiation (SUR) with ambient temperature may be an influencer on athletes’ sweat loss in different environments, but the results are not currently known. The purpose of this study was to determine the effects of SUR on fluid balance (FB) and hydration status (HS) in athletes exercising indoors and outdoors. Initial FB and HS were assessed in NCAA-DI female soccer athletes (n=10) of a single team in temperate, dry conditions (55-68°F, 18-48% humidity) who were monitored during 3 practices of equal estimated energy expenditure (EE): two outdoors in direct SUR (cold/moderate temperatures) and one indoors without SUR (moderate temperatures). Humidity, temperature, and wet bulb globe temperature (WBGT – a measurement partly based on SUR, including ambient temperature/relative humidity) were recorded using Heat Stress Meters placed in the direct sun or in the shade. Each athlete’s semi-nude dry body weight was recorded before and after exercise. Urine samples were taken before, after, and the morning after. Urine specific gravity (USG) was tested to assess HS. Athletes wore combined heart rate and activity monitors to estimate EE and were provided ad libitum water and/or a zero-calorie sports drink. Their total intake included weights of consumed food and drink. Sweat rate was calculated using body weight change and intakes of liquids minus urine losses/hour. Two-way repeated measures ANOVA analyzed group-level differences. No significance was found in total FB (1.01±0.32 L/hr) or EE/hr (444±97.1 kcal/hr) across all days (p>0.05). In analyzing individual athlete results, 40% had consistent USG >1.025 (p=0.001) suggesting potential dehydration. These 4 athletes selected water as their beverage, of which is known that consuming only water does not stimulate drinking behavior as does electrolyte drinks. The remaining 60% were overall not dehydrated (USG <1.025) but must be aware of incidental dehydration in hotter temperatures. The conclusion is that in low-moderate temperatures, athletes self-regulate drinking habits and achieve fluid balance during exercise with or without sun radiation. However, athletes with average USG >1.025 are likely to remain dehydrated in moderate temperatures. The findings suggest that more education would benefit these athletes by ensuring hydration in any environment.
Dissertation/Thesis
Masters Thesis Nutrition 2019

The purpose of this study was to determine the: 1) knowledge, attitudes, and behaviors toward hydration and fluid replacement among collegiate football players at an NCAA Division I University, overall , and the relationship, if any, by position on the team, number of seasons played, and previous nutrition education; 2) relationship between the athletes’ hydration knowledge, attitudes and behaviors; 3) current sources of nutrition information likely to be used by the football players; and 4) players’ perception of the adequacy of, and barriers to, their fluid intake before, during, and after exercise. The players’ mean Hydration Knowledge Score was 14.2 ± 1.4 out of 17 (83.5%). Common misconceptions included: 60% thought water, rather than sports drinks, should be consumed when exercising for more than one hour; 54% did not believe sports drinks are better at restoring muscle glycogen than water; 47% believed salt tablets kept players from getting dehydrated; and 42% indicated thirst is the best indicator of dehydration. No differences were detected by number of seasons, position or previous nutrition education.
Department of Family and Consumer Sciences

Hydration reactions within the oceanic crust incorporate significant amounts of water and incompatible and volatile elements from the Earth's surface into the oceanic lithosphere. During subduction, the altered oceanic crust releases a sequence of metamorphic dehydration fluids, which carry with them a significant portion of the fluid-mobile element inventory. Together, fluid cycling and plate tectonics enable geochemical interaction between the outer regions of our planet and its inner depths. However, aqueous fluids are transient and cannot be observed directly in deeper geological environments. Instead, the nature of fluids must be reconstructed from mineral records. This thesis focuses on the use of in-situ and small-scale geochemical analysis of different mineral generations and intra-mineral zonation to resolve the nature and evolution of fluids in oceanic and subduction environments. Noble gas, halogen and SHRIMP oxygen isotope analyses are supplemented with routine analytical methods including SEM, EPMA, and LA-ICP-MS. Boron isotope analysis with SHRIMP II is also tested and developed, allowing precise investigation of natural suites of metamorphic tourmaline. The first part of the thesis documents a geochemical investigation of hydrated lithologies from the upper detachment surface of the Atlantis Massif using samples collected during IODP Expedition 357. In-situ analyses of lizardite-chrysotile serpentinites reveal that multi-stage serpentinization is linked to shifts in δ18O, and that significant isotopic and trace element heterogeneity between polymorphs and serpentinization stages is present at the microscale. Individual SHRIMP analyses have δ18O ranging from 0 to 6‰, and serpentine generations within individual samples have mean δ18O of -0.2 to +4.4‰. Ranges in oxygen isotope composition are similar between sites, and give consistently high estimates for serpentinization temperatures during all stages of hydration (up to 350°C). Halogen and noble gas abundances of serpentinites, hydrated gabbro and talc-amphibole-chlorite schists from the Massif are lower than previously investigated lizardite-chrysotile serpentinites. Serpentinites contain 28-430 μg/g of Cl, and exhibit 40Ar/36Ar up to 538. Amphibole exerts a strong control on halogen abundances in talc schists. Noble gases are fractionated from seawater abundance patterns, and record a variety of processes including radiogenic ingrowth (He), addition of excess Ar and fractionation related to mineral trapping at different alteration temperature. Oxygen isotope ratios and trace element, halogen and noble gas abundances attest to generally high fluid fluxes and dominant high temperature of serpentinization at the Atlantis Massif. The second part of the thesis investigates metamorphic fluid-rock interaction within a section of subducted upper oceanic crust in the UHP Lago di Cignana Unit and underlying Zermatt-Saas serpentinites near Valtournenche (NW Italian Alps). This study reveals previously undocumented trends and shifts in garnet δ18O, serpentine δ18O and tourmaline 11B. Evidence for multiple stages of metasomatism near peak metamorphic conditions is preserved within a select few samples where outer garnet growth zones exhibit major element, trace element and isotopic shifts (up to 15‰ zonation in δ18O) which require infiltration of externally derived fluids. Multiple stages of fluid infiltration are identified. In two samples fluid derived from serpentinized ultramafic lithologies can be confidently identified as a metasomatic agent, likely preceded by fluids derived from nearby mafic units. Unit-scale tourmaline δ11B heterogeneity is observed, with differences of up to 10‰ observed over the cm to dm-scale; variations of similar magnitude are observed within individual samples. Individual tourmalines exhibit zonation in δ11B to slightly higher values (minor) and lower values (most pronounced in calcschists). Variations in sample-mean tourmaline δ11B may largely reflect protolithic δ11B diversity, slightly modified through dehydration reactions towards lighter δ11B. Significant boron isotopic heterogeneity is preserved near the slab interface even at sub-arc conditions. Together these investigations provide novel insights into seafloor hydration and subduction dehydration of the altered oceanic crust, and demonstrate the utility of microscale oxygen isotope analyses coupled with complementary geochemical tracers to provide detailed constraints on hydrothermal alteration conditions and fluid sources in seafloor and subduction settings.