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Item Acoustic non-destructive testing for wood : a thesis by publications presented in fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Albany, New Zealand(Massey University, 2023) Abu Bakar, Adli Hasan BinThe ability to measure the stiffness of wood is important as it can be used to determine the optimal usage of the timber sample to maximise profitability and increase sustainability. The stiffness of trees and logs is measured in order to segregate them into different grades. Stiffness measurements are also made on juvenile trees and seedlings for breeding trials to improve the stiffness quality of future plantations. The traditional static bending test is considered the gold standard for measuring the stiffness of wood. However, this method is destructive, costly and difficult to use. Non-destructive testing (NDT) techniques have therefore been developed to mitigate these issues. Acoustics is the most common NDT technique used to measure wood stiffness. The time-of-flight method is the only acoustic method which can be used on standing trees. However, literature has shown that stiffness measurements obtained using the time-of-flight method can have a significant overestimation. Studies have reported the potential causes of this overestimation but the exact cause is still not known. In recent years, NDT techniques such as guided wave techniques have been developed for other industries. Guided wave testing is extensively used on metallic structures such as pipes and bars. However, there have been very few studies that utilize guided waves for wood. This thesis investigates the use of guided wave knowledge to identify the cause of the overestimation and to obtain improved NDT measurements. This thesis contains some of the first reported works to perform guided wave measurements on cylindrical wood samples. The results from guided wave experiments show that enhancement and suppression of desired wave modes can be achieved using a ring array of shear transducers. The effects of dispersion on ToF measurements are investigated and it was found that dispersion can be a potential cause of overestimation. Guided wave techniques were developed to obtain acoustic velocity and stiffness measurements for wood. The measurements were compared with the traditional resonance, ToF and static bending methods and improved measurements were obtained. More work can be done to further develop guided wave tools and techniques to be used in the wood industry.Item Identification of mechanical parameters to be used as a firmness standard on quality evaluations of stored blueberry : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand(Massey University, 2022) Rivera Smith, SebastianBlueberry firmness is considered a relevant quality variable influencing consumer acceptability of fresh blueberries. However, the blueberry supply chain and research community have not yet adopted a standard method to measure firmness on postharvest quality evaluations. This thesis has focused on characterising the mechanical properties of blueberry ‘Nui’ and ‘Rahi’ as influenced by different factors such as storage relative humidity (i.e., fruit water loss), controlled atmosphere and harvest maturity. The mechanical parameters were obtained by using the instrumental methods of texture profile analysis (TPA) equipped with a flat plate and the penetration test equipped with a 0.39 mm round tip diameter needle probe. Mechanical parameters of hardness slope (BHS, also known as chord stiffness) of TPA and displacement at skin break (DSk) of the penetration test can be used to track water loss changes in stored blueberries. The DSk and BHS can also accurately detect quality changes induced by controlled atmosphere storage. In addition, BHS can detect maturity differences in stored blueberries, but the force at skin break (FSk) provides better detection of maturity differences at harvest evaluations. To demonstrate the relevance of chord stiffness evaluations at a commercial level, sensory evaluation of texture of hand-touch firmness using a formal sensory panel setting and trained assessors was related to instrumental mechanical parameters. Chord stiffness measured as BHS using a flat plate compression and skin break slope (SSk) measured using a needle probe were strongly related to consumer sensory perception of hand-touch firmness. A blueberry batch with an average BHS ≤0.47 kN m⁻¹ or SSk ≤0.13 kN m⁻¹ was associated with a very high likelihood of unmarketable berries (i.e., berries are ‘soft’ or ‘very soft’). In summary, BHS was an informative parameter of blueberry quality across factors inducing the textural changes and providing commercially relevant information about consumer acceptability. These results can assist the development of a standard instrumental method to measure postharvest firmness on blueberry quality evaluations for research and commercial purposes. Further studies should focus on validating the feasibility of BHS to determine blueberry quality across other sources of textural variation, such as calcium and ethylene-related treatments. In addition, threshold values for mechanical parameters related to consumer acceptance (sensory analysis) may be identified across an extensive range of blueberry genotypes and using other sensory descriptors also relevant to the consumers, such as crispness. Finally, this research identifies alternative areas for further studies, such as the blueberry firming (an increase of firmness during storage) occurring consistently on blueberries ‘Nui’ stored under high RH in regular air or a controlled atmosphere of 5 kPa CO₂ + 4 kPa O₂.Item Biophysical investigations of cells focusing on the utility of optical tweezers : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics at Biophysics and Soft Matter Group, School of Fundamental Science, Massey University, New Zealand(Massey University, 2021) Pradhan, SusavThe aim of this thesis was to explore the utility of different biophysical techniques, particularly optical tweezers (OT), in the investigation of the mechanical properties and interactions of biological samples. Specifically, MCF7 cells and their extracted nuclei were investigated mechanically, while the adhesion property of selected bacteria to the milk fat globule was also used as an exemplar. Biological cells have the ability to actively respond to external mechanical forces exerted by the microenvironment. The cellular response can be viscous, elastic, or viscoelastic in nature depending on the nature of the applied forces and the mechanical stresses applied. Changes in the mechanical properties of cells and nuclei have emerged as a prominent hallmark of many human diseases, particularly in neurodegenerative and metastatic diseases. In this thesis, to understand the application of these techniques to biological systems better, bulk rheology and microrheology studies were first performed on a model viscoelatic fluid (PEO). Particularly, the passive and active microrheology of this model viscoelastic material was characterized using optical tweezers and video particle tracking to develop the prerequisite experimental and analytical methods. Using the experimental knowledge gained from applying optical tweezers to standard materials, a mechanistic approach was developed in order to better understand how the mechanical properties of MCF7 cells change when the amount of heterochromatin protein (HP1a) present inside the nuclei was reduced. (HP1a) is an architectural protein that establishes and maintains heterochromatin, ensuring genome fidelity and nuclear integrity. While the mechanical effects of changes in the relative amount of euchromatin and heterochromatin brought about by inhibiting chromatin modifying enzymes have been studied previously, here we measure how the material properties of the cells are modified following the knockdown HP1a. Indentation experiments using optical tweezers revealed that the knockdown cells have apparent Young’s modului significantly lower than control cells. Similarly, tether experiments performed using optical tweezers revealed that the membrane tensions of knockdown cells were lower than those of control cells. This assay led to further work on studying the mechanical properties of nuclei extracted from MCF7 cells. A combination of atomic force microscopy, optical tweezers, and techniques based on micropipette aspiration was used to characterize the mechanical properties of nuclei extracted from HP1a knockdown or matched control cells. Similar to the previous finding on cells, local indentation performed using atomic force microscopy and optical tweezers found that the knockdown nuclei have apparent Young’s modului significantly lower than control nuclei. In contrast, results from pipette-based techniques in the spirit of microaspiration, where the whole nuclei were deformed and aspirated into a conical pipette, showed considerably less variation between HP1a knockdown and control, consistent with previous studies reporting that it is predominantly the lamins in the nuclear envelope that determine the mechanical response to large whole-cell deformations. The differences in chromatin organisation observed by various microscopy techniques between the MCF7 control and HP1a knock-down nuclei correlated well with the results of our measured mechanical responses and our hypotheses regarding their origin. Finally, not just the mechanical properties of the cells but also their interactions (an interaction between the milk fat globule membrane and two bacterial strains - Lactobacillius fermentum strains - 1487 and 1485) was explored as a side project by probing with optical tweezers. The difference in bacterial cell surface properties of these two strains and its effects on intestinal epithelial barrier integrity has already been studied. This study focuses on measuring the adhesion force between membrane and bacteria using optical tweezers. The results suggested that L. fermentus AGR1487 strongly interacts with MFGM compared to AGR1485. All in all, this thesis demonstrates how biophysical techniques can provide valuable insights into understanding biological systems.Item A multi-compartmental mathematical model of the postprandial human stomach : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Anatomy and Physiology at Massey University, Palmerston North, New Zealand(Massey University, 2020) Mary Vijay, NikhilaComputational fluid dynamics of the human stomach helps to understand the gastric processes such as trituration, mixing, and transit of digesta. Their outcomes give greater insight into the design of food and orally dosed drug delivery system. Current models of gastric contractile activity are primarily limited to the gastric antrum and assume global values for the various physiological characteristics. This thesis developed a unified compartmental gastric model with correctly informed anatomical and physiological data. The gastric geometry incorporated the actions of multiple compartments, such as the gastric fundus, body, antrum, pyloric canal, proximal duodenal cap, and the small intestinal brake. Lattice-Boltzmann Method (LBM) is used to simulate the fluid dynamics within the stomach. This thesis quantified the effects of transgastric pressure gradient (TGPG) between the fundus and the duodenum, the effect of antral propagating contraction (APC) amplitude, and the viscosity of the gastric contents on gastric flow, mixing, and gastric emptying. The results of this work suggest that TGPG influences gastric emptying where as APCs do not play major role in gastric emptying. Flow rate without TGPG obtained in this work agrees with previous work (Pal et al., 2004); however, it is higher in the presence of a TGPG. Results show that APCs promote recirculation, and the amplitude of APC is vital in this regard. The 'pendulating' flow of gastric content observed in this work is reported previously in duplex sonography experiments (Hausken et al., 1992). This work quantified the gastric shear rates (0.6 - 2.0 /s). This work also suggests that the viscosity of the content influences gastric fluid dynamics. This work is a simplified first step towards a 3D gastric model. Hence, these simulation studies were performed under two simplifications: dimensionality and rheology, i.e., we have assumed a Newtonian fluid flow in 2D gastric geometry. A 3D gastric model with more rheologically realistic fluid to explore the pseudoplastic fluid dynamics within the stomach in the future is recommended.Item The biomechanical properties of the collateral ligaments in the equine distal forelimb : a thesis presented in partial fulfillment of the requirement of the degree of Master of Science in Animal Science, School of Veterinary Science, Massey University, Manawatu, New Zealand(Massey University, 2018) Legg, KylieAt the gallop, high loading forces are experienced in the equine distal limb, resulting in stresses to the soft tissue structures of the distal forelimb. Ligaments and tendons attenuate and reduce the concussive effects of the forces acting on the limb and their injury is the most frequent cause of musculoskeletal injury (Clayton, 2016; Clegg, 2012; Woo et al., 2000). Computer models of equine motion estimate the forces in the equine distal limb during motion, providing insight into the biomechanical factors that cause musculoskeletal injury. However, currently models do not account for all structures in the distal limb (Bullimore et al., 2006; Farley et al., 1993; Harrison et al., 2010; McGuigan et al., 2003), particularly the collateral ligaments (CL). This study aimed to determine the biomechanical properties of the collateral and distal sesamoid ligaments of the equine distal forelimb. CL and the straight and oblique distal sesamoid ligaments were harvested from the proximal interphalangeal joint (PIP), metacarpophalangeal joint (MCP), carpus and elbow joints of the forelimbs of 10 Thoroughbred and 9 other equine breeds (total: 19 horses). The elastic moduli (EM) were determined by tensile testing the ligaments with a strain rate of 1 mms-1 after 10 cycles of preconditioning load. The EM of the ligaments differed significantly between the joints, according to position and function. The highest EM was for Thoroughbred MCP joint CL (63 ± 45 MPa, p < 0.05) and the lowest EM for all breeds was the lateral collateral elbow ligament (3 ± 2 MPa, p = 0.14). Thoroughbred horses had a significantly higher EM in the CL of the PIP (27 ± 14 MPa vs. 12 ± 7 MPa) and MCP (63 ± 45 MPa vs. 35 ± 15 MPa) joints than the other breeds in the study (p < 0.05). There was a large variation in EM, negatively affected by age and, in the distal ligaments, wither height (p < 0.05). The mechanical properties described here will be of use in creating the ‘Anybody’ model of the equine distal forelimb being developed at Massey University to determine the effect of ground surface perturbations on the distal limb.Item The stickiness curves of dairy powder : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Bioprocess Engineering at Massey University(Massey University, 2004) Zuo, Jenny YPowder stickiness problems encountered during spray drying are important to the dairy industry. Instantaneous stickiness is a surface phenomena that is caused by exceeding the glass transition temperature of the amorphous sugar in the powder, usually lactose in dairy powders. Instantaneous stickiness occurs at a certain temperature above the Tg of amorphous lactose and has been denoted as the critical "X" value. Whether powder particles are sticky or not depends on whether there is enough liquid flow on the surface between the particles. Two particles stick to each other when there is enough liquid flow to form a bridge between them after the contact. This project aimed to measure the instantaneous sticky point conditions for various dairy powders and to relate these to the operating conditions to give a commerical outcome for the dairy industry. The particle-gun rig was developed to simulate the conditions in the spray drier and the ducting pipe and cyclone. The stickiness of powder particles occurs after a short resident time in the particle-gun. Thus, stickiness is a surface phenomenon and the point of adhesion is the instantaneous sticky point. The amount of deposit on the plate was measured at a temperature, with increasing relative humidity. At a particular temperature and relative humidity, the powder stuck to the stainless steel plate instantaneously. This was observed by a sudden change in % deposition on a % deposition verse RH plot. The T-Tg plot and stickiness curve profile were developed to determine the critical "X" value for the dairy powders. The critical 'X' value is the temperature which exceeds the Tg of amorphous lactose when instantaneous stickiness occurs. The critical "X" values tor various dairy powders including WMP, SMP, MPC, whey protein, buttermilk, white cheese powder and GLUMP powder were found to be 33-49°C. 37-42°C. 42-51C. 50°C, 37-39°C, 28.5°C, and 40.7°C respectively. In addition, the slope of the trend line in the T-Tg plot, indicates how quickly the particular powder becomes sticky once the instantaneous sticky point has been exceeded. The particle-gun rig demonstrated that powders with greater than 30% amorphous lactose are more likely to cause blockage than powders with less than 30%. Both the critical 'X' value and the slope are unique to the powder. The stickiness curve was used to relate the powder surface stickiness condition with the drier outlet temperature and relative humidity. It was recommended to operate at conditions below the stickiness curve for a powder to avoid any chamber or cyclone blockages caused by stickiness. The slope enables a decision to be made about how close to the critical point a plant should be run for a particular powder. The inlet air temperature or concentrate feeding rate can be used to move the operating conditions towards or away from the stickiness curve, according to the operating situations.Item Lactose smearing in transport lines : a thesis presented in partial fulfilment of the requirements for the degree of Masters in Process Engineering at Massey University(Massey University, 2002) Mcleod, JeremyThe smearing of lactose in pneumatic conveying lines, leads to cakes of lactose building up within the lines. This is an undesirable situation as it leads to reduced throughput, caused by the narrowing of the lines and the increase in downtime required to unblock and clean the pipes. This study was carried out to investigate the causes of smearing and identify solutions to this problem. Impact testing was carried out, to look at the breakage behaviour of lactose. This identified that energy of impact is the main consideration for the breakage of lactose in pneumatic conveying. This is not only the energy contained before impact, but also the way in which the energy is dissipated during contact. The use of rubber proved an effective technique in lowering the amount of breakage, due to its ability to adsorb and disperse the impact energy during contact. Testing was carried out looking at the ability of sliding contact to cause the adhesion of lactose to a surface. The results showed that combination of the frictional forces and the sliding velocity can provide enough energy to cause the lactose to adhere. The conclusion drawn was the same as that for impact testing, with energy being the main consideration in the breakage and adhesion of lactose to surfaces. A link between amorphous lactose formation and the smearing was found, with the build up in the conveying lines having a higher amorphous concentration than was found on the free flowing lactose powder. An attempt to show a change in the amorphous concentration of α-lactose crystals after impact proved unsuccessful, although the use of a polarised microscope showed the formation of amorphous lactose on the impact surface. Calculations looking at the amount of amorphous lactose that would have formed after impact, identified that the concentrations were below the levels measurable using the methods available. Following on from impact testing work, a rubber lined bend was placed in a section of the conveying line at Lactose New Zealand. Monitoring of this bend showed it to be successful in preventing the adhesion of lactose to walls of the conveying pipe. However, there was a small amount of wear observed at the entrance of the bend. This was concluded to be due to a design defect as the rubber was raised above the level of the main line. More testing needs to be done, with a change in design, to allow a conclusion on the applicability of rubber for preventing lactose buildup to be drawn.Item Injection moulded radiata pine fibre reinforced polymer composites : properties and applications : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Product Development at Massey University(Massey University, 2004) Sethuram, VishwanathNew Product Development (NPD) is important for an organization's growth, profitability and competitiveness. The product being developed depends on an organization's unique context and could either be market-driven or technology-driven. Technology-driven product development begins with a new proprietary technology, and the firm then identifies products where the technology can be applied. Models like Technology Stage-GateTM have been suggested for developing new technology-driven products. But this process has the drawback of isolating the technology development process from the product development process. The present project began with the observation that New Zealand had an enormous amount of Pine wood fibre resource at her disposal, and there was growing research and use of wood fibre reinforced polymer composites worldwide for applications like automotive interior components, decking, furniture, and so on. Development of commercial products with this material was limited to thermoforming, extrusion, and compression moulding process. Although there was limited research initiated into injection moulding of pine wood fibre reinforced polymer composites, there was no documentation of the effect of varying the melt temperature on the mechanical properties of the material. There was also no documentation, either of commercial injection moulded products that have been manufactured with this material, or of the process that could be employed to develop commercial products with the new material. This led to the broad research aim of identifying a commercial product idea that could be manufactured by injection moulding the composite material that was developed using wood fibre and medium density polyethylene powder (rotational moulding grade) and to document the process adopted to achieve this. Some of the objectives were to document the properties of the composite material that was developed without either pelletising, or modifying the properties of the wood fibre by chemical means. The effect of change in fibre content, melt temperature and fibre length were studied. The fibre content ranged from 10% to 40% (in steps of 10%), and the experiments were conducted at four melt temperatures (155° to 215°C, in steps of 20°C), and for two fibre lengths (up to 4mm, and between 4mm and 8mm). The results of the experiments were statistically analysed using the 'Analysis of Variance' method, for their significance. A new development model, "Technology Driven - Fuzzy Front End" (TD-FFE), was used to manage the "fuzzy" stage of developing the new material, identifying new product ideas, and analysing the product concepts. The model is discussed in detail. Brainstorming technique was adopted to identify new product ideas for the material. The effect of the increase in fibre content on the tensile properties of the composite material was found to be more significant, compared to the effect of melt temperature. The interaction between fibre content and melt temperature on the tensile properties of the composite material was also found to be significant. The results of testing the composite material indicated that addition of wood fibre to the polymer increased the viscosity of the polymer melt. The density of the composite was found to increase with increase in fibre content (up to 40%). The tensile properties of the material increased steadily with increase in fibre content up to 30%, after which it decreased. The maximum ultimate tensile strength was found to be about 20MPa (when moulded at 175°C). The brainstorming technique was not found to be very suitable for the current project as the number of new product ideas identified were very limited since there were constraints on the material and manufacturing method to be used. Nevertheless, the method identified a building foundation insulation and boxing product. The performance of the product was simulated using COSMOS software and from the results of the static stress analysis, it was concluded that the composite material had the required tensile strength to withstand the pressure exerted by wet concrete. A broad analysis to determine the financial viability of the product was also conducted. It was found that it was cheaper to manufacture the new product than assemble the formwork boxing in the traditional method. It offered additional benefits like improving the insulation of the house, and the feel (or appearance) of the foundation, and also could reduce the construction time of the foundation. It is hence recommended that the product concept be investigated in greater detail by conducting consumer and market research to determine its commercial feasibility, and take it through to production and into the market.Item The effect of lactose source on the stickiness of dairy powders : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Bioprocess Engineering(Massey University, 2006) Murti, Rosalind AThe particle gun provides a valuable method to investigate powder stickiness properties. This method gives reproducible results when used under constant testing conditions and allows the isolation of factors influencing stickiness behaviour such as velocity and angle of impact. The (T-Tg)critical and rate of stickiness development obtained from the particle gun method were functions of the air velocity, angle of impact, powder aw and ambient air conditions. Under constant testing conditions (feed rate of 0.3 g.s -1, air velocity of 20 m.s-1, ambient air at < 50%RH, room temperature and constant powder aw (T-Tg)critical was reproducible within ± 0.8°C while the rate of stickiness development was reproducible within ± 0.45 %deposition/°C. The results obtained from the particle gun were consistently higher than the fluid bed results and can be explained by the different impact time and force experienced by the particles. Particle gun results can successfully be used to predict blockages in cyclones provided the appropriate correction is made for particle impact force and time. Blockage data from Te Rapa D5 indicates that the critical T-Tg where blockages occur in the cyclones is 27°C for SMP. Currently D5 is running satisfactorily for SMP at a T-Tg value of 28°C. Under these operation conditions the cyclone wall temperature results in a T-Tg value of 33°C. the same (T-Tg)critical value predicted by the particle gun for standardised SMP. This implies that the cyclone is operating correctly at the maximum T-Tg value before particles become sticky enough to cause blockage problems. Protein standardisation of milk powder via the addition of milk permeate or lactose solution had no detectable effect on the stickiness characteristics of SMP or WMP as measured by the particle gun or the fluid bed rig. No difference was seen in either the bulk or surface composition of the milk powder. This provides evidence to dispel speculation by operators that permeate standardisation produces a more difficult to handle powder.