Resumo: O objetivo deste estudo foi avaliar a influência do acréscimo de 10% de cloreto de cálcio (CaCl2) no tempo de presa, solubilidade, desintegração, pH e atividade antimicrobiana do MTA Branco (MTA) e cimento Portland branco com radiopacificador (CPB). O ProRoot MTA (PRO), com e sem CaCl2, também foi incluído no teste de atividade antimicrobiana. O teste do tempo de presa inicial seguiu a especificação #57 da ADA e o do tempo de presa final a da ASTM (C266-03). Para os testes de solubilidade, desintegração e pH foram utilizados 6 anéis de teflon para cada cimento, medindo 4 mm de espessura e 12 mm de diâmetro interno com parede de 2 mm. Depois de preenchidos, os anéis foram mantidos por 24 e 72 h e 7, 14 e 28 dias em água MiliQ, que foi renovada no fim de cada período. Após cada período, os cimentos foram desidratados em dessecador com sílica por 24 h. Foi registrado o peso de cada cimento hidratado e desidratado. O pH da água onde os cimentos permaneceram imersos foi medido por um pHmetro. A atividade antimicrobiana foi avaliada pela técnica da difusão em ágar, empregando o método do poço. Os microrganismos utilizados foram procedentes da ATCC: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Candida albicans, Staphylococcus epidermidis. O acréscimo do CaCl2 proporcionou uma diminuição de 50% do tempo de presa inicial dos cimentos. Já o tempo de presa final do MTA foi diminuído em 35,5% e o do CPB em 68,5%. Os resultados do teste de solubilidade mostraram que o MTA+CaCl2 absorveu água e não perdeu peso com o passar do tempo, exceto no período de 24 h. O MTA, tanto hidratado quanto desidratado, perdeu peso, mas com valores aceitáveis pela ADA. O CPB apresentou maior solubilidade, a qual foi diretamente proporcional ao tempo de imersão das amostras. Entretanto, o acréscimo do CaCl2 ao CPB diminuiu...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the influence of adding 10% calcium chloride (CaCl2) on the setting time, solubility and dissolution, pH, and antimicrobial activity of white MTA (MTA) and Portland cement with radioopacifier (CPB). ProRoot MTA (PRO) with and without CaCl2 was also included in the antimicrobial activity test. Setting time testing followed the specification #57 of ADA and final setting time testing was made according to C266-03 ASTM standard. Six teflon rings (4 mm thickness, 12 mm internal diameter, 2 mm height) used for the solubility, dissolution, and pH tests were stored in deionized water for 24h, 72 h, 7d, 14d, and 28d, which was renewed at the end of each storage period. After the storage periods, the specimens were dehydrated in a desiccator containing silica gel for 24h. The specimens were weighted before and after dehydration and pH of water was measured using a pH-meter. Antimicrobial activity was evaluated using an Agar well diffusion technique. The following microorganisms were used: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Candida albicans, and Staphylococcus epidermidis (ATCC). Adding of CaCl2 yielded a 50% reduction of the initial setting of the cements. Final setting time of MTA cement was reduced approximately 35.5% and CPB's final setting time was reduced by 68.5%. Solubility results have shown that the MTA+ CaCl2 absorbed water and did not lost weight with time, except for the 24h-storage period. Hydrated and dehydrated MTA presented weight loss, but within acceptable limits stated by ADA. CPB presented greater solubility, proportional to the immersion time, i.e., the greater the storage period the greater the weight loss. However, adding CaCl2 to the CPB did not decrease the solubility. Both CPB and CPB+ CaCl2 did not satisfy ADA requirements. (Complete abstract, click electronic access below) / Orientador: Roberto Miranda Esberard / Coorientador: Clovis Monteiro Bramante / Banca: Marco Antônio Hungaro Duarte / Banca: Wilson Tadeu Felippe / Banca: Mario Tanomaru Filho / Banca: Idomeo Bonetti Filho / Doutor

‘Lord Baltimore’ hardy hibiscus (Hibiscus moscheutos L.) was used in the mass encapsulation protocol, rinsing effects on bulk encapsulation, growth comparisons using K-NAA, acclimatization to greenhouse environment, and leaf anatomy comparisons. Nodal segments, each containing a single axillary bud, were harvested and cut to 4mm prior to mass encapsulation. Results showed that using 2.75% alginate with a concentration of 60 or 80 mM calcium chloride produced an alginate mass, or “cookie”, which was able to hold together during rinsing protocols. The rinsing study resulted with the potential to reduce rinse times from 2 three-minute rinses to 1 one-minute rinse. After 4 weeks under mist, ~58% of root growth was generated when using 1 one-minute rinse. After 8 weeks under mist, the greatest percentage of shoot and root growth occurred when using 1 one-minute rinse. The use of K-NAA in the gel matrix, after four weeks, resulted in no discernable differences. Concentrations of 0 or 0.1 µM will generate a greater percentage of shoot and root growth. Using 1.0 µM K-NAA, and extending the time under mist to 8 weeks, will result in a greater percentage of shoots and roots generated. Acclimatization study investigated the survival rates on mass encapsulated nodal segments, looking at different media, depth of planting and humidity. Increases in shoot lengths can be expected up to 8 weeks under mist and planted either on top or 1 cm deep. A reduction in root growth was seen when placed on top of the medium after 4 weeks. The anatomical study found differences in the leaf cell lengths based on the stage of leaf development. However, there was no indication of a gradual change in anatomy as they adapted from in vitro to greenhouse environment. The best results were found when comparing epidermal, palisade and spongy mesophyll cells on the fourth fully expanded leaf under mist. Hydrangea quercifolia ‘Snow Queen’ was used to test the effects of tissue culture media and plant growth regulators. Research found that using dichloroisocyanuric acid (NaDCC) resulted in a decrease of contamination on explants without a reduction in the number of shoots produced. This would reduce the amount of time and labor on the encapsulation procedure, as no rinsing is required. The best result, looking a nutrient formulation, was found to be WPM with 1 µM BA added.

No description available.

No / Production of titanium is challenging and expensive due to the energy energy-intensive and time-consuming processes used at present. Current commercial production method reduces titanium tetrachloride with magnesium or sodium to produce titanium metal. Several researchers have attempted electro-deposition of titanium from ionic solutions but have faced difficulties in eliminating multivalent titanium ions and highly reactive dendrite products. In this paper, we report, for the first time, the solid-solid phase transformation of titanium dioxide with calcium metal, under suitable conditions, to form solid titanium metal powder (>98% pure) without any oxygen impurity. On phase characterisation, it was found that homogeneous alpha-titanium was produced. The paper also includes the results and interpretations obtained using quantitative analysis, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and phase diagram. The process is simple, green, rapid and cheap compared to the existing methods.

Made available in DSpace on 2014-06-11T19:34:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-01-24Bitstream added on 2014-06-13T18:45:47Z : No. of bitstreams: 1 lima_ma_dr_jabo.pdf: 538530 bytes, checksum: 2342b94d3c4158a909a0895facf7c72a (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Avaliou-se os efeitos da aplicação de giberelina, citocinina, auxina, cloreto de cálcio e 1-metilciclopropeno, assim como de embalagens e refrigeração na conservação pós-colheita de goiabas 'Paluma' e 'Pedro Sato'. As aplicações foram feitas utilizando-se uma solução de manitol a 300mM como veículo e utilizando-se infiltração a vácuo (500 mmHg por 20 minutos). No 1º experimento os frutos tratados com os reguladores e com o cálcio foram armazenados a 21,6ºC, 73,4% UR. Os tratamentos com cloreto de cálcio a 1% ou 2% propiciaram uma vida de prateleira de 7 dias às goiabas 'Paluma' ou seja, aumentou-lhes esta vida em um dia. As goiabas 'Pedro Sato', tratadas com CaCl2 a 2%, ácido indolacético (IAA) e ácido giberélico (GA) a 100 mg.L-1 apresentaram vida útil de 8 dias, ou seja, aumentada em 2 dias. No 2º experimento testou-se a combinação do CaCl2 a 2% com GA ou com IAA, a 200 mg.mL-1, e também a combinação destes três produtos (CaCl2xGAxIAA). Os frutos da 'Paluma' e da 'Pedro Sato' foram armazenados a 24,90C e 78,5%UR e a 23,80C e 69,0%UR, respectivamente. A associação entre CaCl2xGAxIAA foi a melhor na conservação pós-colheita destes frutos, assim como a CaCl2xIAA para as 'Paluma' e a CaCl2xGA para as 'Pedro Sato', pois levaram a menor perda de massa fresca, mantiveram a aparência e propiciaram-lhes aumento de dois dias na vida útil. No 3º experimento, os frutos destas duas cultivares foram submetidos aos tratamentos: Testemunha (sem tratamento); CaCl2 a 2% e ácido giberélico a 200 mg.L-1 e em seguida embalados em bandejas de polietileno tereftalatado (PET), revestidas com filme de polietileno de baixa densidade tendo 5% da área perfurada, celofane ou cloreto de polivinila (PVC) , antes do armazenamento a 10°C e 94ºC... . / The effects of gibberellin, cytokinin, auxin, calcium chloride and 1-methylcyclopropene as well as packaging and cooling on postharvest conservation of guavas 'Paluma' and 'Pedro Sato' were evaluated. The applications were done using a 300 mM mannitol solution as carrier and vacuum infiltration (500 mm Hg for 20 minutes). In the first experiment fruits were treated with growth regulators and calcium and stored at 21.6ºC, 73.4% RH, treatments with calcium chloride at 1% or 2% yielded a 7-day shelf life for 'Paluma' guavas, that is, increased its shelf life for one day. 'Pedro Sato' guavas, treated with CaCl2 at 2%, indole-acetic acid (IAA) and gibberellic acid (GA) at 100 mg.L-1 yielded an 8-day shelf life, that is, an increase of 2 days. In the 2nd experiment a combination of do CaCl2 a 2% with GA or with IAA, at 200 mg.mL-1 and also a combination of these three products (CaCl2xGAxIAA) was evaluated. 'Paluma' and 'Pedro Sato' fruits were stored at 24.9ºC and 78.5% RH and at 23.80C and 69.0% RH. The association of CaCl2xGAxIAA was the best for post harvest conservation of these fruits, as well as CaCl2xIAA for 'Paluma' guavas and CaCl2xGA for 'Pedro Sato', since they lead to smaller loss of fresh weight, maintained fruit appearance and increase shelf life by two days. In the 3rd experiment guava fruits of these two cultivars were subjected to the treatments: control (no treatment); CaCl2 at 2% and gibberellic acid at 200 mg.L-1 and were subsequently packaged in polyethylene tereftalatado (PET) trays, covered by a low density polyethylene with 5% of its area perforated, cellophane or polyvinyl chloride (PVC), before storage at 10°C. Calcium and gibberellic acid did not have an affect on fruit ripening, but PVC film was more efficient on fruit conservation than cellophane, which was better than the perforated polyethylene... (Complete abstract, click eletronic address below).

M.S.

The fate of E. coli O157:H7 and Salmonella spp. during osmotic dehydration of apples was determined at different processing temperatures, times and calcium chloride (CaCl2) concentrations. Apple slices were inoculated to achieve an 8 log CFU/ apple slice concentration of a five strain mixture of E. coli O157:H7 or Salmonella spp. and were soaked in sucrose solutions (60% w/w). In the first study, apple slices were subjected to osmotic dehydration at three different temperatures: 20°C, 45°C and 60°C. In a second study, CaCl₂ was added in the sucrose solution at concentrations of 2%, 4% and 8% to determine its efficacy as an antimicrobial agent. The storage effect of osmotic dehydrated apples on pathogen survival was also tested for seven days at 4°C. Samples were withdrawn at appropriate time intervals, diluted with 0.1% peptone water and surface plated onto recovery media. Recovery of E. coli O157:H7 was compared on Tryptic Soy Agar + 50 ppm nalidixic acid (TSAN) and MacConkey Sorbitol agar (MCS). Recovery of Salmonella was compared on TSAN and XLD agar. There was lower microbial reduction at the lower temperatures tested with approximately 1.0 and 3.0 log CFU/apple slice reduction at 20°C and 45°C, respectively. The population reduction of cells was highest at 60°C, with an approximate five log reduction for both microorganisms (P<0.001). CaCl₂ used as an additive in the osmotic solution, was associated with slightly higher reduction of both E. coli O157:H7 and Salmonella spp. Greater than a 5 log reduction was observed when the combination of CaCl₂ (8%) and 60°C processing temperature was used. During refrigerated storage E. coli O157:H7 and Salmonella decreased by approximately 4.5 log CFU/apple slice, but were still recoverable via direct plating at Day seven. The results of this study show that the survival of E. coli O157:H7 and Salmonella in osmotically dehydrated fruit is influenced by the osmotic processing method used and the level of additive (i.e., CaCl₂) utilized. Parameters associated with decreased survival of pathogens, and therefore, improve product safety, include increasing temperature and time of processing and increasing concentration of CaCl₂. However, E. coli O157:H7 and Salmonella in artificially contaminated apple slices, survived osmotic dehydration processing and subsequent storage under processing and storage parameters of this study. Therefore, processors who produce osmotically dehydrated fruit must consider the potential food safety impact of the osmotic dehydration processes they choose. / Master of Science

Thesis (M.Sc.( Agriculture (Horticulture)) -- University of Limpopo, 2022 / Avocado fruit ‘Hass’ exocarp changes colour from green to purple and black during ripening. However, uniform purple or black exocarp colour is not achieved during ripening, leading to consumers' rejection of fruit for not meeting quality standards. Avocado ‘Hass’ fruit harvested early remain green or develop a multicoloured appearance, concurrently devaluing their commercial value; and, therefore, unattractive to consumers. Therefore, this study aimed to investigate the role of sucrose and calcium postharvest pulsing on early matured ‘Hass’ avocado exocarp colour change during ripening. In this study, early matured ‘Hass’ avocado fruit were harvested from Halls and Sons, Mataffin farm (25°25’39.13” S, 30°55’52.84” E), Nelspruit, South Africa with 10 cm pedicel at commercial dry matter content (22%). Thereafter, the fruit were transported to the University of Mpumalanga laboratory. In the laboratory, the study was divided into two experiments: Experiment 1 ‘Hass’ fruit were continuously infused through the pedicel with different sucrose concentrations; 0 (control), 0.2 and 0.5 mM L-1. Experiment 2 fruit were infused with different calcium chloride (CaCl2) concentrations; 0 (control), 2 and 3 mM L-1. In both experiments, treated and untreated fruit were stored at 5.5°C for 28 days. After removal from cold storage, fruit were ripened at room temperature (±25°C) and evaluated every other day for firmness, subjective colour (visual colour), objective colour parameters (lightness-L*, chroma-C* and hue angle- h°), external chilling injury and ripening percentage. The results showed that Su (0.2 mM L-1) pulsing extended the ripening period by one day, corresponding with maintained fruit firmness. Furthermore, Su (0.2 mM L-1) treated fruit reduced the ‘Hass’ avocado fruit chilling injury index (CII) during cold storage. With respect to colour change, Su (0.5 mM L-1) treated fruit developed purple colour when compared with Su (0.2 mM L-1), which only developed to olive colour on the final ripening day (day 6). In addition, the results showed that all sucrose concentrations had a significant decreasing effect (P < 0.05) on objective colour parameters (L*, C* and h°) and increasing visual colour rating. With respect to CaCl2 treatments, fruit firmness decline was significantly delayed, which resulted in extended ripening time. Moreover, CaCl2 (2 and 3 mM L-1) significantly decreased (P < 0.05) pericarp objective colour parameters (L*, C* and h°) and increased visual colour rating and developed purple colour on the final ripening day (days 6 and 8, respectively). In addition, pulsing with CaCl2 (2 and 3 mM L-1) concentration reduced chilling injury during storage compared with control fruit. In conclusion, the results of this study indicated that Su and CaCl2 applied as postharvest treatments may contribute to avocado colour development by increasing anthocyanin accumulation. However, future research is required to investigate whether these treatments affect anthocyanin biosynthesis at the gene level.

Considerable experimental evidence supports the concept that the growth of plants generally decreases progressively as the salt concentration of the substrate increases, but certain relationships between plant and substrate are still not fully understood. The chemistry of salt toxicity to plants involves many interactions both as to the quantity and kind of ions presented to the roots and those accumulated in the plants. Many plant species have shown sensitivity to excess accumulation of specific salts frequently encountered in saline soils. Thus Eaton (1942), Wadleigh, Hayward, and Ayers (1951 ) have shown most of the fruit trees to be susceptible to injury as a result of the accumulation of chloride ion. Wadleigh, et al. (1951) have reported orchard grass to be sensitive to calcium salts. Recently, Brown, Wadleigh, and Hayward (1953) have found calcium chloride more toxic to some fruit trees than isosmotic levels of sodium chloride. These and other studies have indicated a greater influence of specific ions than of the osnotic pressure of the solution.

Osmotic distillation is a process of removing water from an aqueous solution, driven by water vapour pressure gradient across a hydrophobic membrane. The process occurs at or below ambient temperature and under atmospheric pressure. This research project investigates the osmotic distillation process in hollow fibre modules using hollow fibres PP375, PV375 and PV660 supplied by Memcor Australia. Operating conditions such as temperature, feed concentration and brine cross flow velocity, but not the feed cross flow velocity, were found to have significant effect on the flux. Models for heat and mass transfers were used to study the polarisation phenomena in osmotic distillation. Temperature and concentration profiles at the membrane surfaces due to polarisation were quantified. Scholfield and Ordinary Diffusion models for flux prediction based on the bulk conditions were developed and validated. Models for water activity and viscosity of aqueous glucose and calcium chloride solutions were also developed and validated in this work. / Master of Science (Hons)