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Effect of nutrition on postharvest quality and grey mould development in strawberries.Naradisorn, Matchima January 2008 (has links)
Strawberries are an extremely perishable fruit mainly due to their soft texture and sensitivity to fungal infection. The fungal pathogen Botrytis cinerea is responsible for grey mould on strawberries and is the main causal agent of postharvest decay and subsequent economic loss. As an alternative to fungicides, manipulation of plant nutrition, such as calcium and boron, has been suggested as a means of disease management. This project investigated the effects of calcium and boron application on fruit quality and grey mould development in strawberry. The effect of calcium on fruit quality, grey mould development and leaf blight in strawberry cultivars ‘Aromas’ and ‘Selva’ was investigated through preharvest and postharvest applications. To determine the effect of preharvest application, calcium sulphate in 0.25X strength Hoagland’s solution was applied at 0, 100, 300 and 500 ppm Ca through fertigation. Fully-ripened fruit were harvested and evaluated for postharvest quality at harvest and then after storage at 10⁰C, 90±5% RH for 2 to 10 days. Although fruit firmness of both cultivars declined slightly during storage, this was not affected by preharvest calcium application. Similarly, preharvest calcium treatment had no effect on the external appearance, pH, soluble solids content (SSC) or titratable acidity (TA). No grey mould development was observed on fruit at harvest when flowers were inoculated with a conidia suspension of B. cinerea (10⁴ conidia per mL). However, fruit harvested from plants that received calcium at any concentration had less incidence of grey mould during storage at 10⁰C, 90±5% RH for 14 days than fruit harvested from plants that received no calcium for both cultivars. For ‘Aromas’, 79% and 51% of fruit, and for ‘Selva’, 69% and 43% of fruit, showed rot when treated with 0 and 500 ppm Ca, respectively. The shelf life of ‘Aromas’ and ‘Selva’ increased by about 8% when plants received 500 ppm Ca in comparison with plants that received 0 ppm Ca. After 7 days of incubation at 22 to 24⁰C, there was no difference between blight lesions on wound-inoculated detached leaves from different calcium treatments for either cultivar. However, the lesions on ‘Selva’ were smaller than on ‘Aromas’. The calcium levels in leaves from plants that received calcium at any concentration were adequate for strawberry growing and significantly higher (P < 0.05) than in leaves from plants that received 0 ppm Ca. However, calcium treatment did not ensure transfer of calcium to fruit tissues. Calcium lactate and calcium chloride were used as postharvest calcium treatments at 1500, 3000 and 4500 ppm Ca. Fruit of ‘Selva’ were dipped in calcium solution for 5 min and wound-inoculated with B. cinerea (10⁶ conidia per mL). Calcium lactate and calcium chloride at 3000 and 4500 ppm Ca, respectively, were most effective in delaying Botrytis rot development on ‘Selva’ after 7 days of storage at 10⁰C, 90±5% RH. Storage for least 24 h after calcium dips prior to inoculation was required to delay the development of fruit rot. Fruit harvested early in the season seemed to be less susceptible to grey mould than those harvested later. However, calcium treatment tended to be more effective when applied to late-season fruit. Preharvest boron treatment, applied as for calcium but at 0, 0.25, 0.5 and 1.0 ppm B, had no effect on fruit firmness of either cultivar. However, firmness of ‘Aromas’ fruit was slightly greater than ‘Selva’ fruit for all treatments. The amount of boron applied had no effect on the external appearance, pH, SSC or TA for either cultivar after storage of fruit for up to 10 days. Application of boron had no effect on fruit grey mould development in either cultivar. Furthermore, boron had minimal effect on the incidence of blight on woundinoculated detached leaves of ‘Aromas’ 7 days after inoculation. However, blight lesion diameters on ‘Selva’ leaves in the 1.0 ppm B treatment (8.0 mm) were significantly smaller (P < 0.001) than in the 0 ppm B treatment (13.0 mm). Phytotoxicity was observed in boron treatments even at the level considered optimum for strawberry growing. Severity increased with increasing boron concentration but no consistent effect on flower death or flower abortion was observed. In conclusion, strawberry is sensitive to boron toxicity. Calcium may enhance fruit firmness and, consequently, delay grey mould development if calcium penetrates the fruit. Postharvest calcium treatment tended to be more effective in delaying development of grey mould when applied to late-season fruit. Calcium lactate is a potential alternative to calcium chloride for reducing decay caused by B. cinerea in strawberry without providing undesirable bitterness. This finding may provide a basis for application in industry. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1331382 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine 2008
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Mould Resistance of Full Scale Wood Frame Wall AssembliesBlack, Christopher January 2006 (has links)
The primary objective of this study was to investigate mould growth resistance of different types of wood products which include the sheathing and framing within full scale wall assemblies. Secondary objectives were to investigate the difference in mould growth resistance between borate-treated and untreated wood products as well as provide information about mould growth under different temperature and humidity conditions for treated and untreated wood products. <br /><br /> The objective of the study is to better understand mould growth, and to examine the effects of varying high moisture conditions on wooden products and the mould growth which may result. More importantly this will be examined on full scale wall assemblies; to date mould growth studies have only been performed within a laboratory on small samples of materials. Moreover, this study recreates the conditions which evidently cause mould growth on full scale wall assemblies. Tests were performed within a climate chamber on three full scale wall assemblies. The original scope of this study included an examination of the sheathing and framing components within a full scale wall assembly, however this study will focus mainly on the sheathing. <br /><br /> Results of this study indicate that the relative humidity conditions needed for mould growth on wood are higher than originally believed (i. e. , significantly greater than 80%RH). During the first eight weeks of test number one the relative humidity at the surface of the sheathing was held constant at 95% and little mould growth was observed on the untreated sheathing (mould growth index of 3 or less); little or no mould growth on the treated sheathing (mould growth index of 1 or less). The second and third tests demonstrated that the presence of liquid water greatly accelerated the time to germinations, the amount of mould growth (up to a mould growth index of 6), and the rate of mould growth. All three tests clearly showed that borate-treatment reduced the amount of mould growth; however, the concentration of borate-treatment, and the types of materials treated, does affect the resistance of mould growth. Furthermore, there was some evidence to suggest Borate treatments of the plywood increased the time to germination significantly, from a few weeks to 16 weeks in this study, but once mould growth was initiated, the rate of mould growth was similar to that of the untreated plywood. Two mathematical models to determine mould growth were examined: Viitanen and WUFIBIO (Sedlbauer). Viitanen?s model predicted time to germination and rate of growth rate well for untreated plywood, and WUFIBIO predicted time to germination but not the growth rate. It was also found both models err on the side of caution in predicting mould growth. <br /><br /> Recommendations include improvements to the test method and producers, and for future work.
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Mold Feature Recognition using Accessibility Analysis for Automated Design of Core, Cavity, and Side-Cores and Tool-Path Generation of Mold SegmentsBassi, Rajnish January 2012 (has links)
Injection molding is widely used to manufacture plastic parts with good surface finish, dimensional stability and low cost. The common examples of parts manufactured by injection molding include toys, utensils, and casings of various electronic products. The process of mold design to generate these complex shapes is iterative and time consuming, and requires great expertise in the field. As a result, a significant amount of the final product cost can be attributed to the expenses incurred during the product’s design. After designing the mold segments, it is necessary to machine these segments with minimum cost using an efficient tool-path. The tool-path planning process also adds to the overall mold cost. The process of injection molding can be simplified and made to be more cost effective if the processes of mold design and tool-path generation can be automated.
This work focuses on the automation of mold design from a given part design and the automation of tool-path generation for manufacturing mold segments. The hypothesis examined in this thesis is that the automatic identification of mold features can reduce the human efforts required to design molds. It is further hypothesised that the human effort required in many downstream processes such as mold component machining can also be reduced with algorithmic automation of otherwise time consuming decisions.
Automatic design of dies and molds begins with the part design being provided as a solid model. The solid model of a part is a database of its geometry and topology. The automatic mold design process uses this database to identify an undercut-free parting direction, for recognition of mold features and identification of parting lines for a given parting direction, and for generation of entities such as parting surfaces, core, cavity and side-cores. The methods presented in this work are analytical in nature and work with the extended set of part topologies and geometries unlike those found in the literature. Moreover, the methods do not require discretizing the part geometry to design its mold segments, unlike those found in the literature that result in losing the part definition. Once the mold features are recognized and parting lines are defined, core, cavity and side-cores are generated. This work presents algorithms that recognize the entities in the part solid model that contribute to the design of the core, cavity and side-cores, extract the entities, and use them in the design of these elements. The developed algorithms are demonstrated on a variety of parts that cover a wide range of features.
The work also presents a method for automatic tool-path generation that takes the designed core/cavity and produces a multi-stage tool-path to machine it from raw stock. The tool-path generation process begins by determining tool-path profiles and tool positions for the rough machining of the part in layers. Typically roughing is done with large aggressive tools to reduce the machining time; and roughing leaves uncut material. After generating a roughing tool-path for each layer, the machining is simulated and the areas left uncut are identified to generate a clean-up tool-path for smaller sized tools. The tool-path planning is demonstrated using a part having obstacles within the machining region. The simulated machining is presented in this work.
This work extends the accessibility analysis by retaining the topology information and using it to recognize a larger domain of features including intersecting features, filling a void in the literature regarding a method that could recognize complex intersecting features during an automated mold design process. Using this information, a larger variety of new mold intersecting features are classified and recognized in this approach.
The second major contribution of the work was to demonstrate that the downstream operations can also benefit from algorithmic decision making. This is shown by automatically generating roughing and clean-up tool-paths, while reducing the machining time by machining only those areas that have uncut material. The algorithm can handle cavities with obstacles in them. The methodology has been tested on a number of parts.
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Design of Mould Opening and Closing Cam-Link MechanismChen, Shih-han 20 January 2011 (has links)
Composed of a left mold and a right one, an open and close molding mechanism is widely used in various plastic industries. The aim of this study is to design cam-link mechanisms whose right mold motions can rapidly synchronize with their left mold motions so that the mechanisms have higher stiffness for reducing residual vibration.
In structural design of a molding mechanism, the device is actuated by a planar cam mechanism. And a set of cam actuated links is synthesized to drive the left mold. Then, another set of links connected to one of the left mold links is used to synchronously actuate the right mold together with the left mold.
This study first is to synthesize the B-Spline curves for the left mold motion. Subsequently, the linkage sizes are modified base on the mechanical advantages. Then, the motion curves of the right mold and the cam follower device can be analytically determined. And the rigid body dynamic behavior of the mechanism is analyzed. Finally, the geometry of the cam is analyzed and the size of the cam follower rollers are selected to achieve the longer life time at the working speeds.
This research presents eight different design cases to investigate the kinematic and dynamic characteristics of the molding mechanism. As a result, a case with improved kinematic and dynamic performance is selected.
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Experiments Concerning the Mold Materials Used in the Production of the Copper Ingots from the Late Bronze Age Shipwreck Excavated at Uluburun, TurkeyLarson, Thomas S. 14 January 2010 (has links)
Underwater excavations of a Late Bronze Age shipwreck at Uluburun, Turkey
recovered a combined 475 oxhide and plano-convex discoid copper ingots. While the
hoard of ingots excavated at Uluburun brings the total number of copper ingots from the
Late Bronze Age to over 1000, interestingly, only one ingot mold from the that period
has been identified. Scholars have speculated over the means behind the creation of
these ingots for decades, but with a relative absence of archaeological molds the most
promising method of reaching any conclusions as to the types of molds used in antiquity
seems to be experimentation.
Experimental archaeology, has, in recent years been responsible for many
breakthroughs in how the past is viewed. In the face of an overwhelming disparity of
copper ingot molds from the Late Bronze Age, trials designed around testing different
mold materials and casting techniques have the potential to determine, with relative
certainty, how copper ingots were cast over 3000 years ago. This thesis examines the possible materials used to create copper ingot molds
through a study of their prevalence in antiquity and also details experiments in which
these materials were used, in concert with different casting techniques, to create copper
ingots. The results of these experiments are combined with analyses of the Uluburun
ingots in an effort to bring some closure to the debate surrounding copper ingot molds in
the Late Bronze Age.
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Expression of defense genes in sorghum grain mold and tagging and mapping a sorghum anthracnose resistance geneKatile, Seriba Ousmane 15 May 2009 (has links)
Sorghum grain mold and anthracnose are two major diseases of sorghum
(Sorghum bicolor) that constrain sorghum production worldwide. Grain mold is caused
by several species of fungi, but the two most common are Curvularia lunata and
Fusarium thapsinum. Isolates of these two species were used to inoculate panicles of
selected sorghum cultivars in green house and field experimentations. Panicles were
sprayed at the time of anthesis with conidial suspensions of the two fungal species
individually or in a mixture and with water to serve as a control. Samples were collected
48 hours after inoculation for RNA extraction. In greenhouse studies, four cultivars
(Tx2911, Sureno, SC170 and RTx430) were used while thirteen cultivars were grown in
the field experiments. Gene expression was measured for the following genes using real
time polymerase chain reactions (rt-PCR): PR10, β-glucanase, chitinase, thaumatin,
sormatin, phenyalanine ammonia lyase (PAL), obtusifoliol 14α-demethylase (Obtus),
antifungal protein (AFP), apoptosis related protein (Apop) and leucine rich repeat
(LRR).
Seed germination tests in field grown cultivars indicated that germination rates
for SC279-14E, SC660 and Sureno were not greatly influenced by grain mold. Covering
the panicles with bags served to protect them against grain mold pathogens. The seed
mycoflora test showed that Fusarium thapsinum was the most frequently recovered
species and there were more species present in non-covered panicles.
The response of sorghum cultivars to grain mold infection involves multiple
defense genes. Real time PCR used to study the expression of sorghum defense in greenhouse grown plants showed that mRNA encoding PR-10, a small 10 kDa protein,
was highly expressed in the glumes and spikelets of resistant cultivars Tx2911 and
Sureno and constitutively in leaves. The expression of some other defense genes like
beta-glucanase, chitinase and AFP was variable. Sormatin was not expressed. Expression
of β-glucanase, chitinase, and PR10 was higher in field than in greenhouse experiments.
A second area of research involved tagging of a resistance gene for sorghum
anthracnose. Three AFLP markers (Xtxa607, Xtxa3181 and Xtxa4327) and three SSRs
(Xtxp3, Xtxp55 and Xtxp72) were identified. These markers were loosely linked to the
resistance genes. The markers are located on linkage group B. The results suggest that
markers located 20-30 cM on one side or the other of those tested should provide useful
tags for the resistance gene.
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Effects Of Mold Temperature And Vacuum In Resin Transfer MoldingAkgul, Eralp 01 December 2006 (has links) (PDF)
The purpose of this study was to investigate the effects of mold temperature, initial resin temperature, and the vacuum, applied at resin exit ports, on the mechanical properties of epoxy matrix woven glasss fiber reinforced composite specimens produced by Resin Transfer Molding (RTM).
For this purpose, six different mold temperatures (25º / , 40º / , 60º / , 80º / , 100º / , and 120º / C), two initial resin temperatures (15º / and 28º / C), and vacuum (0.03 bar) and without vacuum (~1 bar) conditions were used. Specimens were characterized by using ultrasonic (C-Scan) inspection, mechanical tests (Tensile, Flexural, Impact), thermal analyses (Ignition Loss, TGA) and scanning electron microscopy (SEM).
It was generally observed that mechanical properties of the specimens produced with a mold temperature of 60º / C were the best (e.g. 16%, 43%, and 26% higher tensile strength, Charpy impact toughness and flexural strength values, respectively). When vacuum was not applied, the percentage of &ldquo / voids&rdquo / increased leading to a decrease in mechanical properties such as 26% in Charpy impact toughness and 5% in tensile and flexural strength. Lower initial resin temperature also decreased mechanical properties (e.g. 14% in tensile strenght and 18% in Charpy impact toughness).
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Design And Manufacturing Of A Tactical Unmanned Air VehicleSenelt, Engin 01 October 2010 (has links) (PDF)
The aim of this study is to describe the conceptual design, performance analysis to validate the design and manufacturing steps of Middle East Technical University Tactical Unmanned Air Vehicle (METU TUAV). The system requirements are adopted from a market study and assumed as is. Utilizing competitor search and conceptual design methodology, the rough parameters of the aircraft are defined and a performance analysis is conducted to validate the requirements. After the design team is content that the design is meeting the requirements, material and production techniques are evaluated.
The male and female molds of the aircraft are manufactured with glass fibre fabric and special mold resin. Using the female molds / with glass, carbon and aramid fibre materials and epoxy matrix / utilizing wet-layup and vacuum bagging techniques the METU TUAV is manufactured. Wing, tail and fuselage skins are manufactured first and the reinforcing structures are integrated and cured inside the skins. Then the skins are assembled and the separate components are obtained. The rear landing gear and tail booms are also manufactured from carbon fibre composites. The individual parts are assembled together in special alignment jigs and the METU TUAV is completed.
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The Stability Analysis of Mold Level Control SystemYang, Chu-Kang 28 August 2001 (has links)
The theoretical stability analysis of mold level control system for slab continuous casting machine is presented in this thesis. In the procedure of analyzing the stability of the mold level control system, the PLC program written for the control system is studied first in order to obtain the mathematical model of a PID controller. Then the mathematical models of servo-amplifier, servo-valve, electro hydraulic system to the output of mold level are established. A simulative control system using Matlab software is constructed in accordance with these mathematical models so that not only the results of stability analysis can be verified but also the dynamic response of controlled system can be studied. Finally, the effects of some potential disturbance on system¡¦s dynamics, stability, and control accuracy are also analyzed.
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Expression of defense genes in sorghum grain mold and tagging and mapping a sorghum anthracnose resistance geneKatile, Seriba Ousmane 10 October 2008 (has links)
Sorghum grain mold and anthracnose are two major diseases of sorghum
(Sorghum bicolor) that constrain sorghum production worldwide. Grain mold is caused
by several species of fungi, but the two most common are Curvularia lunata and
Fusarium thapsinum. Isolates of these two species were used to inoculate panicles of
selected sorghum cultivars in green house and field experimentations. Panicles were
sprayed at the time of anthesis with conidial suspensions of the two fungal species
individually or in a mixture and with water to serve as a control. Samples were collected
48 hours after inoculation for RNA extraction. In greenhouse studies, four cultivars
(Tx2911, Sureno, SC170 and RTx430) were used while thirteen cultivars were grown in
the field experiments. Gene expression was measured for the following genes using real
time polymerase chain reactions (rt-PCR): PR10, β-glucanase, chitinase, thaumatin,
sormatin, phenyalanine ammonia lyase (PAL), obtusifoliol 14α-demethylase (Obtus),
antifungal protein (AFP), apoptosis related protein (Apop) and leucine rich repeat
(LRR).
Seed germination tests in field grown cultivars indicated that germination rates
for SC279-14E, SC660 and Sureno were not greatly influenced by grain mold. Covering
the panicles with bags served to protect them against grain mold pathogens. The seed
mycoflora test showed that Fusarium thapsinum was the most frequently recovered
species and there were more species present in non-covered panicles.
The response of sorghum cultivars to grain mold infection involves multiple
defense genes. Real time PCR used to study the expression of sorghum defense in greenhouse grown plants showed that mRNA encoding PR-10, a small 10 kDa protein,
was highly expressed in the glumes and spikelets of resistant cultivars Tx2911 and
Sureno and constitutively in leaves. The expression of some other defense genes like
beta-glucanase, chitinase and AFP was variable. Sormatin was not expressed. Expression
of β-glucanase, chitinase, and PR10 was higher in field than in greenhouse experiments.
A second area of research involved tagging of a resistance gene for sorghum
anthracnose. Three AFLP markers (Xtxa607, Xtxa3181 and Xtxa4327) and three SSRs
(Xtxp3, Xtxp55 and Xtxp72) were identified. These markers were loosely linked to the
resistance genes. The markers are located on linkage group B. The results suggest that
markers located 20-30 cM on one side or the other of those tested should provide useful
tags for the resistance gene.
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