A general equation was derived for calculating the weight-average molecular weight of the sol fraction, after gelation, of crosslinked copolymers formed by condensation polymerisation; the equation includes those of Flory and Stockmayer as special cases. In qualitative agreement with a gel-degradation model based on the general equation, soluble degradation products from a polymer gel of well defined structure displayed a pattern of increasing molecular weight with increasing solubilisation; it was also observed that the second virial coefficient and the refractive index increment showed a particular form of variation with molecular weight. The gel-degradation model, applied to the known chemistry of the acid-sulfite delignification of wood, provided a good fit to the experimental points of the previously known topochemical effect. Studies on the preparation of polyether-gel synthons required a detailed review of phase-transfer-catalysed etherification reactions, and provided an explanation for the lower reactivity of (beta)-haloethers relative to alkyl halides.

No description available.

A series of tests was performed in winter 1996 to measure degradation of paper mulches with the help of physical and mechanical properties. Four types of paper used for mulching, kraft paper gauge 40, 60 and 80 and waxed paper were laid over soil in two growth chambers. They were kept under observation for 27 days under controlled temperature, humidity and light. Mulches were sprayed with water to simulate rain. Tensile and puncture tests were performed on each type of paper every day. Four mechanical properties; stress, strain, energy and tensile energy absorption were calculated from the force-deformation curve obtained by tensile test. Two mechanical properties; displacement and force to break were calculated from the force-deformation curve obtained by puncture test. A special die had to be designed to perform puncture tests. This design eliminated shear loading which otherwise would have been present in normal puncture tests. / Results showed that paper - 3 (kraft paper gauge - 80) was best suited for mulching as the mechanical properties were stable through 27 days with negligible fluctuations. Waxed paper required less force to break but was stable through 27 days of experimentation. / A three-way factorial model was developed to analyze the results statistically. A SAS program was written to model the results. The fitted model was in very good agreement with the actual values.

No description available.

Made available in DSpace on 2014-06-11T19:23:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-03Bitstream added on 2014-06-13T20:50:31Z : No. of bitstreams: 1 rossato_as_me_arafcf_parcial.pdf: 70560 bytes, checksum: 02a69ecc9d43139a848118e7e06954fc (MD5) Bitstreams deleted on 2014-10-03T16:24:39Z: rossato_as_me_arafcf_parcial.pdf,Bitstream added on 2014-10-03T16:27:37Z : No. of bitstreams: 2 rossato_as_me_arafcf_parcial.pdf.txt: 10051 bytes, checksum: 155729f82180bf3afe9f15738f6e2db3 (MD5) 000633863_20161231.pdf: 193204 bytes, checksum: 85e224c698f3a6bc372a57bcf3f0f21c (MD5) Bitstreams deleted on 2014-10-03T16:33:14Z: 000633863_20161231.pdf,Bitstream added on 2014-10-03T16:43:28Z : No. of bitstreams: 2 rossato_as_me_arafcf_parcial.pdf.txt: 10051 bytes, checksum: 155729f82180bf3afe9f15738f6e2db3 (MD5) 000633863_20161231.pdf: 193204 bytes, checksum: 85e224c698f3a6bc372a57bcf3f0f21c (MD5) Bitstreams deleted on 2014-10-03T16:48:54Z: 000633863_20161231.pdf,Bitstream added on 2014-10-03T16:49:46Z : No. of bitstreams: 1 000633863_20161231.pdf: 193204 bytes, checksum: 85e224c698f3a6bc372a57bcf3f0f21c (MD5) Bitstreams deleted on 2014-10-27T11:47:07Z: 000633863_20161231.pdf,Bitstream added on 2014-10-27T11:48:04Z : No. of bitstreams: 1 000633863_20161231.pdf: 193204 bytes, checksum: 85e224c698f3a6bc372a57bcf3f0f21c (MD5) Bitstreams deleted on 2016-12-19T17:50:13Z: 000633863_20161231.pdf,. Added 1 bitstream(s) on 2016-12-19T17:50:54Z : No. of bitstreams: 1 000633863_20191231.pdf: 202003 bytes, checksum: a1292088f71d2487a0a75c1030cfa857 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As degradações químicas e microbiológicas constituem os principais fatores de deterioração dos alimentos, sendo a oxidação um dos mais importantes processos de degradação por gerar sabores e odores desagradáveis. Como forma de prevenir ou retardar a oxidação, são adicionados ao alimento substâncias antioxidantes, e os condimentos têm demonstrado poder antioxidante, oferecendo uma alternativa ao uso de antioxidantes sintéticos. O objetivo deste trabalho foi elaborar hambúrgueres com carne mecanicamente separada (CMS) de tilápia-do-Nilo com adição de orégano e alecrim, e a avaliação da eficiência destas especiarias como antioxidantes. Foram elaboradas formulações contendo 0,10; 0,15 e 0,20% de orégano ou alecrim e um produto sem antioxidante. A composição centesimal, avaliação microbiológica e análise sensorial foram realizadas no início e final do armazenamento e, periodicamente foram determinados TBARS, BNVT, pH, cor instrumental e contagem de microrganismos psicrotróficos. Os resultados mostraram que o uso de orégano preveniu mais eficientemente a oxidação dos lipídeos durante 120 dias de armazenamento a -18 ºC, avaliado pelos menores valores de TBARS. Entre as porcentagens de orégano utilizadas a 0,20% impediu a oxidação desde o início (0,23 mg MDA.kg-1), e manteve por mais tempo a estabilidade da cor (a*) dos hambúrgueres. Houve interferência nos valores de pH, com menores medidas iniciais com o uso do orégano (6,15 a 6,08), e BNVT não foram alteradas com os condimentos. Não foi detectada presença de Salmonella e os resultados para estafilococos coagulase positiva ficaram dentro dos padrões legais. O orégano 0,20% e alecrim 0,20% nas formulações dos hambúrgueres apresentaram a menor contagem de psicrotróficos aos 120 dias. Pelas análises sensoriais as formulações com orégano foram... / Chemistry and microbiological degradations are the main causes of food deterioration, and oxidation is one of the most important process of degradation because it can generate unpleasant flavor. As a way to prevent or retard oxidation, antioxidant substances are added in the food. The condiments have demonstrated antioxidant activity and offer an alternative in order to replace synthetic antioxidants. The aim of this study is to evaluate the efficiency of oregano and rosemary as natural antioxidants used in tilapia fishburger made with CMS (minced fish) and stored frozen for 120 days. It was elaborated formulations of fishburgers containing 0.10%, 0.15% and 0.20% of oregano or rosemary and one without antioxidant. Protein, fat, moisture and ashes determination, microbiological analysis and sensory evaluations were conducted in the beginning and the end of storage period. TBARS, BNVT, pH, instrumental color and psychrotrophic microorganism count were determined periodically. Oregano was found to be more effective in preventing lipid oxidation during 120 days under freezing (-18 oC), evaluated by TBARS values, and oxidative stability was observed for the formulation with 0.20% of oregano. The antioxidants interfered in pH values, oregano formulations showed the lowest values, and did not cause changes in BNVT. The lower values of TBARS in formulations containing oregano showed that this substance did prevent oxidation more efficiently than rosemary during 120 days of storage under -18 ºC. In relation to the formulations with oregano, the one with 0.20% of oregano had the most oxidation inhibition since the beginning of storage time (0.23 mg MDA.kg-1), and maintained the color (a*) stability for longer duration. There was interference in the pH, the hamburgers made with oregano had the lowest initial values (6.15 a 6.08) and BNVT was unaltered with the condiments... (Complete abstract click electronic access below)

A range of nitrosylmetalloporphyrin complexes, M(porph)NO [M = Fe, Co; porph = TPP, OEP, T[PIV]PP], some labelled with [15]NO, has been synthesised and investigated as structural and spectroscopic models of the cured meat pigment, nitrosylmyoglobin. The nitrosylmetalloporphyrins were found to be unstable in solution (and some in the solid state) with respect to loss or further reaction of the nitrosyl ligand. The diamagnetic cobalt (III) porphyrin nitrosyIs and a range of other square pyramidal complexes of cobalt(III) with an apical nitrosyl ligand have been further investigated by [15]N and [59]Co NMR spectroscopy to establish whether the CoNO group is bent or linear and to study nephelauxetic and spectrochemical effects at the metal. In all cases studied the CoNO group is bent (CoNO ~ 120°). The basal ligands were dithiocarbamate, tetradentate Schiff base, porphyrin, and bidentate diamine and oximate giving S[4], S[2]N[2], N[4], OONN, or ONON coordination in the equatorial plane. The shielding of both cobalt and nitrogen tends to decrease with decrease in M(d) to pi* (NO) back-bonding as indicated by M-N and N-O bond distances, and the MNO angle and the NO stretching frequencies. The shieldings decrease with electron withdrawal by ring substituents and also in going from sulphur to nitrogen to oxygen coligands, i.e. with decrease in ligand field splitting and in the nephelauxetism of the coligands. The bent nitrosyls of cobalt can function as oxygen transfer catalysts via a nitrosyl-nitro couple. Consequently, a range of Co(III) porphyrin nitro complexes, (L)Co(porph)NO[2] (porph = TPP, OEP; L = py, 1Melm) and several nitro complexes containing the other basal ligands have been synthesised and investigated by the [15]N and [59]Co NMR technique. The coordinated nitro ligand is labile and linkage isomerism and ligand exchange have been observed. These observations may be related to the deterioration of cured meat colour which is of importance to the food industry. The crystal structure of (py)Co(TPP)NO[2] is presented; the nitro group of which is rotationally disordered. Recrystallisation of (1MeIm)Co-(TPP)NO[2] gave [Co(TPP)(1Melm)[2]]NO[2], the crystal structure of which has been determined. Formation of this nitrite is further evidence for the lability of the nitro ligand. The known complex Fe(salphen)NO was prepared using ascorbic acid for the first time to prevent contamination with the oxo-bridged iron(III) dimer. Variable temperature [57]Fe Mossbauer effect studies of the S = 1/2 to S = 3/2 spin transition for Fe(salphen)NO show that the crossover is continuous and centred at T[c] ~ 181 K, and that the electronic transition between the two spin states is rapid on the Mossbauer timescale. The fluxionality of CoCl[2]([15]NO)(PPh[2]Me)[2] was studied by variable temperature [15]N and [31]P NMR. An [17]O NMR study of the ?-peroxo complex [(NH[3])[5]Co[17]O[2]Co(NH[3])[5]](NO[3])[4]. 2H[2]O is presented. An attempt to measure [15]N NMR spectra of the diamagnetic 18 electron species, Fe(porph)([14]NO)([15]NO) (porph = TPP, OEP) presumably containing linear FeNO[+] and bent FeNO[-] was unsuccessful.

Seeds of a range of crop species were classified according to their ability to germinate after presowing soaking treatments of varying severity. The differences in soaking tolerance were then compared with changes in several metabolic parameters to determine the importance of metabolic adaptation in the avoidance of soaking injury in seeds. After seed soaking treatments those species most susceptible to injury exhibited the highest respiration rates under nitrogen. At the same time the species with the highest respiration rates under nitrogen showed more rapid utilization of their seed reserves. This was demonstrated as a positive correlation of respiration rate under nitrogen against the fall in sucrose content of seeds on soaking. A similar positive correlation of respiration under nitrogen with alcohol content and with fall in sucrose content on soaking seeds was found. However, when the malic acid content of, seeds was assayed the reverse trend was shown, where malic acid was negatively correlated both with respiration under nitrogen and with the fall in sucrose content on soaking seeds. Thus the changes in the alcohol and malic acid contents of seeds on soaking were negatively correlated with each other. Analysis of lactic acid content of soaked seeds was expressed as the percentage of the three anaerobic products measured (ie. alcohol plus malic acid plus lactic acid) and gave a significant negative correlation against respiration rate under nitrogen' on soaking seeds. Parallel studies of both alcohol and malic dehydrogenases were conducted after soaking seeds. The activity of alcohol dehydrogenase was highest in those species which were least tolerant of soaking injury, while the Michaelis constants for alcohol dehydrogenase with respect to acetaldehyde were low in species intolerant of soaking injury but higher in species tolerant of this treatment. Enhanced metabolic damage was observed as a result of both high (30°C) and of low temperature (0°C) soaking treatments, but only in species which were normally susceptible to soaking injury. In studies on a single species (Pisum sativum) metabolic injury followed a similar course to the above studies in high but not in low temperature soaking treatments. Studies on the enzyme invertase showed grossly enhanced activity with a rise in temperature. This increased activity was also related to germination counts.

The UK’s bridge stock is deteriorating due to a number of mechanisms that affect concrete durability. These include carbonation, thaumasite sulphate reaction, alkali-silica reaction, chloride ingress, freeze-thaw action and fatigue. There are limited resources available to maintain the bridge stock in a safe and operable condition. It is therefore essential that available funds are used to optimum effect for inspections, maintenance, assessment, repair or replacement. If a short term view is taken to bridge management then it is highly likely that a future backlog of essential work will build up which will result in severe financial and operational difficulties. In this context, methodologies that can predict the time-dependent deterioration of RC bridges would be highly beneficial to bridge owners and maintaining agents when developing bridge management strategies. A methodology has been developed in this thesis to estimate the time-dependent deterioration and structural reliability of RC components. Only chloride induced deterioration was modelled because it was found to be the dominant mechanism in the UK. Probabilistic techniques and spatial analysis are used to model the uncertainty inherent to chloride induced deterioration. Code based limit state equations are used with the deterioration models to create time-dependent failure margins. Standard reliability methods (FORM/SORM) are then applied to estimate failure probability time profiles over the life of the bridge. Furthermore, classical and Bayesian statistical techniques are used to update deterioration/reliability predictions. The deterioration models produce plots of area initiated or delaminated as a function of time. These may be used to plan inspection times and types. The ensuing limit state reliability analysis produce probability of failure profiles which may be used as a comparative tool for assessing similar bridge/component types, and thus a bridge management strategy can be developed on the basis of perceived criticality. The updating techniques are used to illustrate how model predictions can be improved when site data becomes available. It is shown that the development of models using typically available site data can be beneficial to bridge owners, but the quantity of such data needs to be enhanced. This is particularly evident for the wide diversity of bridge structures in the UK.

No description available.

Orientador: Maria Regina Barbieri de Carvalho / Banca: Maria da Penha Longo Mortatti Catanozi / Banca: Felipe Shindy Aiura / Resumo: As degradações químicas e microbiológicas constituem os principais fatores de deterioração dos alimentos, sendo a oxidação um dos mais importantes processos de degradação por gerar sabores e odores desagradáveis. Como forma de prevenir ou retardar a oxidação, são adicionados ao alimento substâncias antioxidantes, e os condimentos têm demonstrado poder antioxidante, oferecendo uma alternativa ao uso de antioxidantes sintéticos. O objetivo deste trabalho foi elaborar hambúrgueres com carne mecanicamente separada (CMS) de tilápia-do-Nilo com adição de orégano e alecrim, e a avaliação da eficiência destas especiarias como antioxidantes. Foram elaboradas formulações contendo 0,10; 0,15 e 0,20% de orégano ou alecrim e um produto sem antioxidante. A composição centesimal, avaliação microbiológica e análise sensorial foram realizadas no início e final do armazenamento e, periodicamente foram determinados TBARS, BNVT, pH, cor instrumental e contagem de microrganismos psicrotróficos. Os resultados mostraram que o uso de orégano preveniu mais eficientemente a oxidação dos lipídeos durante 120 dias de armazenamento a -18 ºC, avaliado pelos menores valores de TBARS. Entre as porcentagens de orégano utilizadas a 0,20% impediu a oxidação desde o início (0,23 mg MDA.kg-1), e manteve por mais tempo a estabilidade da cor (a*) dos hambúrgueres. Houve interferência nos valores de pH, com menores medidas iniciais com o uso do orégano (6,15 a 6,08), e BNVT não foram alteradas com os condimentos. Não foi detectada presença de Salmonella e os resultados para estafilococos coagulase positiva ficaram dentro dos padrões legais. O orégano 0,20% e alecrim 0,20% nas formulações dos hambúrgueres apresentaram a menor contagem de psicrotróficos aos 120 dias. Pelas análises sensoriais as formulações com orégano foram... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Chemistry and microbiological degradations are the main causes of food deterioration, and oxidation is one of the most important process of degradation because it can generate unpleasant flavor. As a way to prevent or retard oxidation, antioxidant substances are added in the food. The condiments have demonstrated antioxidant activity and offer an alternative in order to replace synthetic antioxidants. The aim of this study is to evaluate the efficiency of oregano and rosemary as natural antioxidants used in tilapia fishburger made with CMS (minced fish) and stored frozen for 120 days. It was elaborated formulations of fishburgers containing 0.10%, 0.15% and 0.20% of oregano or rosemary and one without antioxidant. Protein, fat, moisture and ashes determination, microbiological analysis and sensory evaluations were conducted in the beginning and the end of storage period. TBARS, BNVT, pH, instrumental color and psychrotrophic microorganism count were determined periodically. Oregano was found to be more effective in preventing lipid oxidation during 120 days under freezing (-18 oC), evaluated by TBARS values, and oxidative stability was observed for the formulation with 0.20% of oregano. The antioxidants interfered in pH values, oregano formulations showed the lowest values, and did not cause changes in BNVT. The lower values of TBARS in formulations containing oregano showed that this substance did prevent oxidation more efficiently than rosemary during 120 days of storage under -18 ºC. In relation to the formulations with oregano, the one with 0.20% of oregano had the most oxidation inhibition since the beginning of storage time (0.23 mg MDA.kg-1), and maintained the color (a*) stability for longer duration. There was interference in the pH, the hamburgers made with oregano had the lowest initial values (6.15 a 6.08) and BNVT was unaltered with the condiments... (Complete abstract click electronic access below) / Mestre