Shrimp and mussel samples were cleaned, washed and exposed to steam before freezing. HHP treatment was performed at combinations of 200, 220 and 250 MPa at 25, 30, 40 and 50&deg / C for 10 and 20 minutes. Microbial analysis were performed by analyzing the effect of treatments on the microbial reduction in the samples. Based on the results of the microbial reduction, the best combinations of HHP treatments were determined as 250 MPa, 50&deg / C, 10 minute for shrimps and 220 MPa, 50&deg / C, 10 minute for mussels where total microbial inactivation was achieved. Storage analysis was performed on the samples, treated at the selected HHP combinations and stored at room (25&deg / C) and refrigeration temperatures (4&deg / C). For the storage analysis, variations in Total Volatile Bases (TVB-N) and pH were measured. According to the results evaluated, shelf-life of the shrimps were detected as 10 and 16 days for storage at room and refrigeration temperature, respectively as compared to 4 days of untreated sample at 4oC. Similarly shelf-life for the mussel samples were obtained as 12 days for storage at room and 18 day for storage at refrigeration temperature as compared to 4 days of untreated sample at 4oC. HHP-at the studied parameters for shrimps and mussels- can be offered as an alternative method for the preservation of shell-fish instead of conventional frozen food technology, which is currently used in the industry, since it gives the opportunity to handle the samples at lower temperatures for the post-production period resulting in both reduction of energy required and operational costs without sacrificing from the quality as measured by microbial reduction, TVB-N and pH.

Drying is a process of moisture removal due to simultaneous heat and mass transfer. High hydrostatic pressure (HHP) processing subjects liquid and solid foods, with or without packaging, to pressures between 100 and 800 MPa. The application of HHP affects cell wall structures, leaving the cells more permeable, facilitating the diffusion and providing higher drying rates. In this study, two variety of apples, i.e. Amasya and red delicious, green beans and carrots were pretreated with HHP at different pressure-time-temperature combinations (100 &ndash / 300 MPa for 5 &ndash / 45 min at 20 and 35&deg / C) prior to drying. Hot air drying experiments were carried at different temperatures (27, 45, 65, and 85&deg / C) and air velocity of 0.4 and 0.8 m/s. To obtain the drying data, samples were subjected to hot air drying under constant external conditions. The applicability of 14 kinetic models selected from the literature for the drying of fruits and vegetables was determined by appropriate statistical analyses procedures. Improving the drying conditions by increasing the drying temperature generally masked the effect of HHP pretreatment on drying rate. Only for green beans, HHP treatments at 20&deg / C decreased the drying rate. Generally pressures of HHP pretreatment higher than 100 MPa caused cell permeabilization resulted in higher drying rates for apples and carrots. Among the 14 models, modified Page model for apples, and modified Page and two term exponential models for green beans and carrots were found to best explain the drying behaviors.

Heat treatment (around 50&deg / C) is a major step in honey filling and packaging that is applied before filtration to decrease viscosity, reduce the moisture level, to destroy yeasts, liquefy crystals and delay crystallization. As a result, formation of Hydroxy Methyl Furfural (HMF), decrease in enzymatic activity, color deterioration, decrease in viscosity and many other structural changes are observed. HMF is produced as a result of Maillard reaction and/or hexose dehydration -which is undesirable-, practically, it is found in fresh honey in low levels, and increases due to heat treatment, storage temperature, pH (acidity) and sugar concentration of honey. HMF level and diastase number are important quality parameters and shelf life indicators of honey. Alternatives of v heat treatment may be the use of ultrasound and high hydrostatic pressure (HHP) to decrease viscosity, liquefy honey and thus minimise adverse affects of heat treatment. Therefore, the aim of this study is to evaluate the effect of HHP (220-330 MPa, 50-60&deg / C, time) and ultrasound (24 kHz) on liquefaction and quality parameters (HMF, diastase number, color and viscosity) of different honey varieties (sunflower, cotton and canola) and to compare the changes with heat treated (50&deg / C and 60&deg / C, time) and untreated honey. Based on the results of the chemical and physical analysis, for HHP treatment the best treatment combination was determined as 220 MPa, 50&deg / C, 106 min. For ultrasound treatment the best treatment combinations were determined as 7 mm probe- 0.5 cycle (batch) applications. On this basis the study points out that Ultrasound and HHP can be suggested as alternative methods to traditional thermal treatment for the liquefaction of honey crystals. When compared to thermal treatment, Ultrasound is advantageous in shorter application times, slight changes in quality parameters and ease in operation. HHP treatment is also an alternative method with shorter application times and lower HMF values.

High Hydrostatic Pressure (HHP) application, alone or in combination with refrigeration, ambient or moderate heating temperatures / inactivates pathogenic and spoilage microorganisms and conserves the product &bdquo / &bdquo / freshness

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 123-128). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 123-128). Also available on the Internet.

Summary Juliane Schneevoigt „Investigation of time- and pressure-dependent expression of different components of the extracellular matrix by chondrocytes in vitro” Institute of Anatomy, Histology and Embryology of the University of Leipzig Submitted in June 2015 98 pages, 34 figures, 41 tables, 153 references keywords: cartilage, chondrocytes, hydrostatic pressure, bioreactor, qPCR Introduction Hyaline cartilage maintains the basic function of transmitting articular pressure load within synovial joints and therefore provides the basis for the movements of an organism. Being a small coverage of the joint surface, it shows a composition designed to match this function specifically. A high amount of proteoglycans and its associated water determines the elastic formability of the hyaline cartilage which allows the absorbance of pressure and shear forces. These proteoglycans, mainly based on aggrecan as core-protein, are embedded into a meshwork of collagen fibres, primarily formed of collagen type II. This composition is not to be understood as a static construct; moreover it is exposed to biophysical forces that permanently require a dynamic adaptation. This adaptation of the extracellular matrix formed by proteoglycans and collagen type II is organised by a small number of embedded chondrocytes, the cells of the hyaline cartilage. As chondrocytes are post-mitotic cells and due to the lack of vascularisation within hyaline cartilage, there is hardly any chance for regeneration of defects in order to maintain the integrity of the tissue. The resulting replacement is formed as fibrocartilage, which has not the capability to withstand the biodynamical forces within the joint. As these defects in hyaline cartilage represent a gross of the diseases of the musculoskeletal system, there is a high medical interest in the development of innovative cell-based therapies, as autologous chondrocyte transplantation (ACT) is one. With this type of therapy in vitro cultivated chondrocytes are seeded into a cartilage defect with the aim of producing hyaline cartilage. Aims of the study In the last decades the need for a detailed understanding of the biodynamics of cartilage became obvious for further development of therapies. The aim of this study was therefore to establish a cell culture system to provide an insight into the biodynamics of chondrocytes. Aside from the examination of the differentiation of in vitro cultivated chondrocytes and their synthesis of extracellular matrix as a function of the cultivation time, another aim of this study was to determine whether the application of hydrostatic pressure might have beneficial influence on the expression of extracellular matrix components by chondrocytes in vitro, in accordance with the hyaline cartilage. Material and methods Human articular chondrocytes were cultivated in vitro without the application of hydrostatic pressure in the first place. The cells were observed phase contrast microscopically and the distribution of collagen type I and II was detected immuncytochemically. In further experiments optical confluent chondrocytes were transferred to a bioreactor system applying a hydrostatic pressure of 5 or 10 bar with variable time periods of the pressure applied. Subsequently, the expression of collagen type I, collagen type II and aggrecan was investigated and quantified using qPCR and Western Blot. Chondrocytes cultivated exclusively without the application of hydrostatic pressure served as controls. In this pilot-study the samples were analysed using arithmetic mean and standard deviation to evaluate the power statistically. In addition, similar test conditions with marginal differences were pooled and the necessary sample size to meet a power of 80 % with an alpha error of 0.05 was calculated using the maximum potential standard deviation. In cases where this statistic power was obtained, an analysis of significance (\"One Way Analysis of Variance”) was carried out meeting a significance level under 0.05. Results During the cultivation of chondrocytes in vitro without hydrostatic pressure the length of the cultivation time did neither show an effect on the phase contrast microscopical morphology nor on the immuncytochemically detected distribution of collagen typ I and II. The application of increased hydrostatic pressure for 24 hours results in a 0.2-0.8-fold decrease of the expression of collagen type I and II and a 1.7-2.2-fold increase of aggrecan expression compared to the unloaded controls. This effect was more distinct with 5 bar but was accompanied by instabilities in the cell culture. This is why further investigations concentrated on the use of 10 bar pressure with subsequently shortened time period of the applied pressure. With short times of loading (1.5 and 3 hours) a pressure load of 10 bar led to a 0.8 fold decrease of the expression of collagen type I and II and showed a 1.6-2.4 fold increase of aggrecan expression. These qPCR results were supported by the protein expression of collagen type I, II and aggrecan detected in Western Blot. Conclusions A cell culture system was established to examine the effect of hydrostatic pressure on the expression of chondrocytes on the one hand, which can further be modified for the assembly of cell transplants on the other hand. Subsequently the results of this study led to a definition of cell culture conditions, stimulating the extracellular matrix production of chondrocytes towards the composition of hyaline cartilage. This was the case using a seeding density of 104 cells/cm2 and a pre-cultivation time of 6 days of normal pressure, followed by the application of 10 bar hydrostatic pressure for 1.5-3 h. With the help of this pilot-study a cell culture system was established to gain more information on biodynamics of hyaline cartilage. Moreover it is possible that this information will provide a basis for further development of cell based therapies of cartilage defects, such as ACT. / Zusammenfassung Juliane Schneevoigt „Untersuchung der zeit- und druckabhängigen Expression verschiedener Komponenten der extrazellulären Matrix durch Chondrozyten in vitro“ Veterinär-Anatomisches Institut der Veterinärmedizinischen Fakultät der Universität Leipzig Eingereicht im Juni 2015 98 Seiten, 34 Abbildungen, 41 Tabellen, 153 Literaturangaben Schlüsselwörter: Knorpel, Chondrozyten, hydrostatischer Druck, Bioreaktor, qPCR Einleitung Der hyaline Knorpel gewährleistet die grundlegende Funktion der Druckübertragung innerhalb der synovialen Gelenke und stellt somit die Grundlage für die Bewegung des Organismus dar. Als schmaler Überzug der Gelenkflächen ist er in seinem Aufbau an diese Funktion spezifisch angepasst. Dabei bedingt der hohe Gehalt an Proteoglykanen und das an diese assoziierte Wasser die elastische Verformbarkeit des hyalinen Knorpels, die es ermöglicht, Druck- und Scherkräfte abzufedern. Die Proteoglykane, die hauptsächlich auf Aggrekan als Kernprotein basieren, sind in ein Maschenwerk kollagener Fasern eingelagert, welches im Wesentlichen durch Kollagen Typ II gebildet wird. Diese Zusammensetzung darf nicht als statisches Konstrukt verstanden werden. Vielmehr ist der hyaline Knorpel in vivo verschiedenen biophysikalischen Einflüssen ausgesetzt, die eine dynamische Anpassung erfordern. Solche Anpassungsvorgänge in Form einer Änderung der Zusammensetzung der aus kollagenen Fasern und Proteoglykanen bestehenden extrazellulären Matrix werden durch die wenigen eingelagerten Chondrozyten, die Zellen des hyalinen Knorpels, organisiert. Da die reifen Chondrozyten jedoch keine Zellteilungen aufweisen und dem hyalinen Knorpel eine Vaskularisierung fehlt, ist eine Defektregeneration kaum möglich, sodass eine Wiederherstellung der Integrität des Gewebes unterbleibt und stattdessen ein Ersatzknorpel, der Faserknorpel, gebildet wird, welcher den einwirkenden biodynamischen Belastungen jedoch nicht standhalten kann. Da die Defekte des hyalinen Knorpels einen Großteil der Erkrankungen des Bewegungsapparats darstellen und zudem die Arthrose als Langzeitfolge nach sich ziehen, besteht ein hohes medizinisches Interesse an der Entwicklung zellbasierter Therapieansätze, wie der Autologen Chondrozytentransplantation (ACT). Hierbei werden - bislang mit unterschiedlichen Erfolgen – in vitro kultivierte Chondrozyten mit dem Ziel, neuen hyalinen Knorpel zu bilden, in einen Knorpeldefekt eingebracht. Ziele der Untersuchungen In den letzten Jahrzehnten zeigte sich, dass die Entwicklung von Therapieansätzen zur Behandlung von Knorpeldefekten ein detaillierteres Verständnis des Knorpelgewebes und speziell dessen Biodynamik erfordert. Ziel dieser Arbeit war es daher, im Rahmen einer Pilotstudie, ein In-vitro-System zu etablieren, welches die Untersuchung der Biodynamik der Chondrozyten ermöglicht. Neben der Untersuchung der Morphologie der Chondrozyten und der durch sie synthetisierten extrazellulären Matrix in Abhängigkeit von der Kultivierungszeit der Zellen, wurde die Fragestellung bearbeitet, ob durch die Wirkung eines hydrostatischen Drucks günstige Effekte in Hinblick auf die Expression einer extrazellulären Matrix, wie sie im hyalinen Knorpel vorliegt, erzielt werden kann. Materialien und Methoden Eine Primärkultur humaner artikulärer Chondrozyten wurde zunächst unter Standardzellkulturbedingungen und atmosphärischem Druck kultiviert. Die Zellen wurden phasenkontrastmikroskopisch und hinsichtlich der Verteilung von Kollagen Typ I und II immunzytochemisch untersucht. In den weiteren Versuchen wurden optisch konfluente Chondrozyten in einen Bioreaktor überführt und weiter unter einem hydrostatischen Druck von 5 oder 10 bar kultiviert. Dabei wurde die Dauer der Druckeinwirkung auf die Chondrozyten variiert. Das Expressionsmuster der so kultivierten Chondrozyten wurde quantitativ in Hinblick auf Kollagen Typ I und II sowie Aggrekan mittels qPCR und Western Blot untersucht. Dabei dienten jeweils Chondrozyten, die ohne erhöhte Druckbedingungen kultiviert wurden, als Kontrollen. In dieser Pilotstudie wurden die Proben unter Berechnung der Mittelwerte und Standardabweichung hinsichtlich ihrer statistischen Power ausgewertet. Neben dieser Analyse der Einzelergebnisse wurden die Versuchsbedingungen, die kaum Unterschiede in den Ergebnissen aufwiesen, in Gruppen zusammengefasst und mit Hilfe der größtmöglichen vorhandenen Standardabweichung der Stichprobenumfang eines Versuchs errechnet, welcher die statistische Power der Ergebnisse bei einem Alpha-Fehler von 0,05 auf 80% erhöht. In den Fällen, in denen diese Power erreicht wurde, erfolgte eine Untersuchung der Unterschiede auf Signifikanz („One Way Analysis of Variance“) bei einem Signifikanzniveau < 0,05. Ergebnisse Während der In-vitro-Kultivierung der Chondrozyten unter atmosphärischem Druck zeigte die Länge der Kultivierungszeit weder einen Einfluss auf die phasenkontrastmikroskopisch untersuchte Morphologie der Zellen noch auf die immunzytochemisch detektierte Verteilung des Kollagen Typ I und II. Die Wirkung eines erhöhten hydrostatischen Drucks (5 bar, 10 bar) für 24 Stunden führte zu einer Abnahme der Expression von Kollagen Typ I und Typ II auf das 0,2-0,8-fache bei gleichzeitiger Zunahme der Expression des Aggrekan auf das 1,7-2,2-fache, verglichen mit der unbehandelten Kontrolle. Dieser Effekt war bei 5 bar ausgeprägter als bei 10 bar, führte jedoch gleichzeitig zu einer starken Instabilität des Zellkultursystems. Vor diesem Hintergrund wurde für den höheren Druck (10 bar) die Zeitdauer der Druckeinwirkung verkürzt. Hierbei konnten bei kurzzeitiger Druckeinwirkung von 10 bar (1,5 und 3 Stunden) bei Erhalt der Zellen ähnliche Effekte erzielt werden wie für die Bedingung 5 bar, 24 Stunden. Die Expression von Kollagen Typ I und Typ II sank auf das 0,8-fache, wohingegen ein Anstieg der Aggrekanexpression auf das 1,6-2,4-fache erreicht wurde. Diese Ergebnisse der qPCR konnten durch die im Western Blot für Kollagen Typ I, II und Aggrekan detektierte Proteinexpression gestützt werden. Schlussfolgerungen Im Rahmen dieser Arbeit wurde ein In-vitro-System etabliert, welches einerseits der Untersuchung des Einflusses von hydrostatischem Druck auf die Expression von Chondrozyten dienen und andererseits für die Herstellung von Zelltransplantaten weiter modifiziert werden kann. Die Ergebnisse der Untersuchungen führten zur Definition von Bedingungen für das In-vitro-System, unter denen die Expression der extrazellulären Matrix durch die Chondrozyten in Richtung der Zusammensetzung im hyalinen Knorpel stimuliert werden kann. Dies zeigte sich bei einer Aussaat der humanen Chondrozyten in einer Konzentration von 104 Zellen/cm2 und einer Vorkultivierungszeit von 6 Tagen unter Normaldruck, gefolgt von der Kultivierung unter hydrostatischem Druck von 10 bar für 1,5 bis 3 Stunden. Mit Hilfe dieser Pilotstudie wurde somit ein In-vitro-System etabliert, auf dessen Basis Untersuchungen durchgeführt werden können, die weiterführende Erkenntnisse zur Biodynamik des hyalinen Knorpels liefern und der zukünftigen Entwicklung zellbasierter Therapieansätze der Knorpeldefekte, wie der ACT, zu Gute kommen.

Thesis (Ph.D.) -- Mississippi State University. Department of Agricultural and Biological Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 92-103). Also available on the World Wide Web.

Graphite is used within a reactor as a moderator and a reflector material. During fast neutron irradiation, the physical properties and dimensions of nuclear graphite are changed significantly. Graphite shrinkage could lead to disengagement of individual component and loss of core geometry; differential shrinkage in the graphite component could lead to the generation of internal stresses and component failure by cracking. The latter behaviour is complicated by the irradiation induced changes in Young's modulus and strength. These dimensional and modulus change have been associated with the irradiation-induced closure of many thousands of micro-cracks associated with the graphite crystallites due to crystal dimensional change. Closure of microcracks in nuclear graphite was simulated by external pressure (hydrostatic loading, deviatory stress and dynamic loading) and not by irradiation, whilst Young's modulus was measured to check if there was any correlation between the two mechanisms. A study of the deformation behaviour of polycrystalline graphite hydrostatically loaded up to 200MPa are reported. Gilsocarbon specimens (isotropic) and Pile Grade A (PGA) specimens are (anisotropic in nature) were investigated. Strain measurements were made in the axial and circumferential directions of cylindrical samples by using strain gauges. Dynamic Young's modulus was also investigated from the propagation velocity of an ultrasonic wave. Porosity measurements are made to determine the change in the porosity before and after deformation and also their contribution towards the compression and dilatation of graphite under pressure. Graphite crystal orientation during loading was also investigated by using XRD (X-ray diffraction) pole figures. Effective medium models were also investigated to describe the effect of porosity on graphite elastic modulus. All the graphite specimens investigated exhibited non-linear pressure- volumetric strain behaviour in both direction (axial and circumferencial). In most of the experiments, the deformation was closing porosity despite new porosity being generated. Under hydrostatic loading, PGA graphite initially stiff then it became less stiff after a few percent of volume strain and then after about ~20% volumetric strain they stiffen up again, whist Gilsocarbon showed similar behaviour at lower volumetric strain (~10-13%). Gilsocarbon was stiff than PGA; this behaviour is due to the fact that Gilsocarbon has higher density and lower porosity than PGA. During unloading, a large hysteresis was formed. The stressed grains are relieved; the initial closed pores began to reopen. It is suggested that during this stage, the volume of pore re-opening superseded the volume of pores closing, the graphite sample volume almost fully recovered. In the axial compression test, PGA perpendicular to the extrusion direction (PGA-AG) was less stiff than PGA parallel to the extrusion direction (PGA-WG); in the hydrostatic compaction test, the PGA-WG sample deformed more because it had to undergo a less complicated shape change. This is because the symmetry of their anisotropy is parallel to the symmetry of the sample. The Pole figures showed an evidence of slight crystal reorientation after hydrostatic loaded up to 200MPa. The effective medium model revealed the importance of porosity interaction in graphite during loading.