Toolpath Planning Methodology for Multi-Gantry Fused Filament Fabrication 3D Printing

Additive manufacturing (AM) has revolutionized the way industries manufacture and prototype products. Fused filament fabrication (FFF) is one of the most popular processes in AM as it is inexpensive, requires low maintenance, and has high material utilization. However, the biggest drawback that prevents FFF printing from being widely implemented in large-scale production is the cycle time. The most practical approach is to allow multiple collaborating printheads to work simultaneously on different parts of the same object. However, little research has been introduced to support the aforementioned approach. Hence a new toolpath planning methodology is proposed in this paper. The objectives are to create a collision-free toolpath for each printhead while maintaining the mechanical performance of the printed model. The proposed method utilizes the Tabu Search heuristic and a combination of two subroutines: collision checking and collision resolution (TS-CCR). A computer simulation was used to compare the performance of the proposed method with the industry-standard approach in terms of cycle time. Physical experimentation is conducted to validate the mechanical strength of the TS-CCR specimens. The experiment also validated that the proposed toolpath can be executed on a custom multi-gantry setup without a collision. Experimental results indicated that the proposed TS-CCR can create toolpaths with shorter makespans than the current standard approach while achieving better ultimate tensile strength (UTS). This research represents opportunities for developing general toolpath planning for concurrent 3D printing

Enhanced conservation biological control of light brown apple moth in vineyards

The light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), is the most damaging insect pest of wine grapes in Australia. Biological control contributes to the management of LBAM. This project aims to enhance the conservation biological control of LBAM by examining how the provision of alternative hosts and native flowering plants can sustain parasitoids like Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae). Native plants and alternative host insects that could support conservation biological control of LBAM in South Australian vineyards are evaluated. The contribution that D. tasmanica makes to biological control of LBAM would be more reliable if this wasp parasitises common alternative hosts, maintains populations on them when the grapevines are dormant, and then moves to attack LBAM when it reinvades vineyards. This study examined the foraging behaviour of D. tasmanica on LBAM and two tortricid species that are associated with vineyards, Acropolitis rudisana (Walker) and Merophyas divulsana (Walker). The reciprocal responses of these insect hosts were also studied to determine their susceptibility to wasp attack. During behavioural assays, all hosts were accepted by D. tasmanica with high parasitism rates. The parasitoid responded differently to different host species. These experiments indicate that populations of D. tasmanica should be conserved, and LBAM more reliably suppressed, if the alternative hosts, M. divulsana and A. rudisana, are present. Host choice between E. postvittana and M. dilvusana by D. tasmanica was also studied in a wind tunnel, where the wasp could express its natural searching behaviour. Choices tests were conducted to examine how natal hosts, host stages and the wasp’s experiences could affect the landing selections of D. tasmanica. Developmental outcomes of parasitoids on different host species were also examined. D. tasmanica exhibited no clear preference for either host. Host species did not affect the body size of the wasp, but did influence its developmental time, probably as a result of differences in the host’s body sizes. The sex ratio of the wasp did not vary between these host species. These results suggest that M. divulsana is a promising alternative host species to support parasitoid populations in vineyards. A field study was conducted to evaluate the potential impacts of candidate plants on biological control of leafrollers, especially LBAM. Five species were planted beside vineyards to provide shelter, nectar and alternative hosts for beneficial insects. The plants were Bursaria spinosa, Leptospermum lanigerum, Hakea mitchellii, Melaleuca lanceolata and Myoporum petiolatum. Similar leafroller abundances and parasitism rates were found between vineyard rows adjacent to the native plants compared to rows furthest from them. The absence of a difference was possibly due to the proximity of the experimental treatment areas and the movement of parasitoids. The results, including increasing parasitoid diversity over time, imply potential benefits of the plants for better leafroller management. The results from my studies suggest that selected supplementary resources can benefit parasitoids and thereby stabilise or enhance biological control of LBAM in vineyards. This research provides a foundation to develop strategies to better suppress LBAM by facilitating more stable biological control.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 201

Nanoscale Photonic Devices Fabricated Using DNA Nanostructures

In the field of DNA nanotechnology, self-assembly is being advanced as the key technology for the creation of nanoscale structures. Popular and effective DNA nanotechnology methods of producing nanoscale structures are branched DNA junctions and DNA origami. DNA nanostructures have recently been employed as scaffolds for the bottom-up arrangement of proteins, as well as semiconductor and metallic nanoparticles, with nanometer precision. Such structures are expected to exhibit unique optical properties and may enable new photonic devices. Conversely, the majority of photonic devices for optical waveguide are fabricated using top-down processes. However, the cost and controllability of complex nanostructures using top-down processes imposes significant challenges. As an alternative to top-down processes, work will be presented demonstrating the use of DNA self-assembly processes to fabricate nanoscale photonic devices for optical waveguide. To fabricate photonic devices using DNA self-assembly, DNA nanostructures were used as scaffolds to configure light emitting molecules so as to create a near-field energy transfer waveguide. Spectrophotometry was used to characterize the device operation. The spectral results indicate that DNA nanostructures functionalized with light emitting molecules can transfer energy through a three molecule system with 28% efficiency, demonstrating the potential of using DNA nanostructures for future photonic devices for optical waveguide

Participatory Land Use Planning for Climate-Smart Villages: Guidelines and References

Participatory land-use planning (PLUP) refers to a bottom-up method of analyzing land and water resources. In its current form, PLUP integrates inputs about climate change and sea level rise to help the community utilize the resources within its vicinities. In utilizing its resources, the community will be able to improve the people’s livelihoods and help them sustain such resources for the benefit of the next generations. This publication in implementing PLUP focused on climate-smart adaptation in Climate-Smart Villages (CSVs)

Effects of plant essential oils and their constituents on Helicobacter pylori : A Review

Essential oils (EOs) obtained from different medicinal and aromatic plant families by steam distillation have been used in the pharmaceutical, food, and fragrance industries. The plant EOs and their broad diversity of chemical components have attracted researchers worldwide due to their human health benefits and antibacterial properties, especially their treatment of Helicobacter pylori infection. Since H. pylori has been known to be responsible for various gastric and duodenal diseases such as atrophic gastritis, peptic ulcer, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma, several combination antibiotic therapies have been increasingly used to enhance the eradication rate of the bacterial infection. However, in the last decades, the efficacy of the therapies has decreased significantly due to widespread emergence of multidrug resistant strains of H. pylori. In addition, side-effects from commonly used antibiotics and recurrence of the bacterial infection have drawn public health concern globally.Therefore, this review focuses on in vitro effects of plant EOs and their bioactive constituents on the growth, cell morphology and integrity, biofilm formation, motility, adhesion, and urease activity of H. pylori. Their inhibitory effects on expression of genes necessary for growth and virulence factor productions of the bacterial pathogen are also discussed. Further in vivo and clinical evaluations are required so that plant EOs and their bioactive constituents can be possibly applicable in pharmacy or as adjuvants to the current therapies of H. pylori infection

An in-situ thermoelectric measurement apparatus inside a thermal-evaporator

At the ultra-thin limit below 20 nm, a film's electrical conductivity, thermal conductivity, or thermoelectricity depends heavily on its thickness. In most studies, each sample is fabricated one at a time, potentially leading to considerable uncertainty in later characterizations. We design and build an in-situ apparatus to measure thermoelectricity during their deposition inside a thermal evaporator. A temperature difference of up to 2 K is generated by a current passing through an on-chip resistor patterned using photolithography. The Seebeck voltage is measured on a Hall bar structure of a film deposited through a shadow mask. The measurement system is calibrated carefully before loading into the thermal evaporator. This in-situ thermoelectricity measurement system has been thoroughly tested on various materials, including Bi, Te, and Bi$_2$Te$_3$, at high temperatures up to 500 K

SCREENING ANTIBACTERIAL ACTIVITY OF VIETNAMESE PLANT EXTRACTS AGAINST HUMAN PATHOGENIC BACTERIA

Objectives: Infectious diseases caused by bacteria are a leading cause of death worldwide. Hence, the objectives of the study are aimed to evaluate the antibacterial activity against five human pathogenic bacteria of methanolic extracts from 66 plants collected from Vietnam. Methods: The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of methanol extracts of 66 plant species against five bacterial strains. Results: In this study, all the plant extracts were active against at least one train with MIC values ranging from 24 to 2048 μg/mL. Twenty-five plant extracts were active against all three Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus). Of these, the extracts of Macaranga trichocarpa (Rchb. f. and Zoll.) Mull. Arg. (Euphorbiaceae), Calophyllum inophyllum L. (Clusiaceae) and Caryodaphnopsis baviensis (Lecomte) Airy Shaw (Lauraceae) exhibited the highest antibacterial activity (MIC =24–128 μg/mL), followed by extracts of Betula alnoides Buch.- Ham. e × . D. Don (Betulaceae), Acronychia pedunculata (L.) Miq. (Rutaceae), Croton alpinus A. Chev. ex Gagnep. (Euphorbiaceae) (MIC =64–256 μg/mL). Furthermore, the extract of Rhus chinensis Mill. (Anacardiaceae) and Annona reticulata L. (Annonaceae) exhibited potent antibacterial activity against the two Bacillus species (MIC =32–64 μg/mL). Conclusion: Results of this study reveal that plant extracts from Vietnam have highly antibacterial activity against Gram-positive bacteria. These results suggest that Vietnamese plant extracts may be a rich source of antibacterial drugs

Defect-free MoS2-flakes/amorphous-carbon hybrid as an advanced anode for lithium-ion batteries

Molybdenum disulfide (MoS2) is a promising alternative for the anode of Li-ion batteries because of its high theoretical capacity and layered structure for rapid ion transport. However, the issues of low electrical conductivity, high volume change, and complicated synthesis are limiting the practical application of MoS2 as the anode in Li-ion batteries. To overcome these issues, we propose the synthesis of MoS2 flakes/amorphous carbon hybrids (MoS2/C) for the application of the anode. The MoS2 flakes are obtained by liquid-phase exfoliation of bulk MoS2 in 2-propanol. Then, MoS2/C hybrids are produced by thermal decomposition of poly(acrylic acid) coated on MoS2. The hybrids are tested as anode-active materials in a half-cell configuration. The electrochemical tests show that the electrode, with the optimized carbon content, exhibits a reversible specific capacity of ∼521 mAh g-1 at 100 mA g-1 after 100 cycles, with a coulombic efficiency approaching 100%. The remarkable performance of the MoS2/ C hybrids is attributed to the carbon network acting as a buffer layer to alleviate the volume change of MoS2. This study demonstrates an approach to enhance the electrochemical performance of MoS2/C hybrids for Li+ storage applications

Workplace wellbeing in community pharmacy practice: A cross-sectional study in Can Tho, Vietnam

Background: Among pharmacy workers, low workplace wellbeing can lead to reduced effectiveness. However, to date, studies on this issue are limited within the community pharmacy setting in Vietnam. Objectives: This study was conducted to identify the component aspects of workplace wellbeing and their associations with demographic characteristics. Methods: The cross-sectional descriptive study was conducted in Can Tho, Vietnam. Self-administered questionnaires were hand-delivered to all pharmacy workers working at selected community pharmacies. The workplace wellbeing scale comprised 18 items. Results: In total, 382 pharmacy workers participated in this study. Factor analysis revealed three fundamental aspects to workplace wellbeing: Factor 1 – perceived self-worth and job satisfaction, Factor 2 – positive emotions with work, and Factor 3 – negative emotions with work. Factor 1 showed a positive correlation with Factor 2, with a correlation coefficient (ρ) of 0.509, while both Factor 1 (ρ = −0.399) and Factor 2 (ρ = −0.416) demonstrated negative correlations with Factor 3. Higher income was associated with higher positive emotions with work (P = 0.008), higher perceived self-worth and job satisfaction (P = 0.013), and lower negative emotions with work (P < 0.001). Conclusion: Workplace wellbeing of pharmacy workers in their professional environments was associated with financial aspects. These findings suggest that policies aimed at improving income for pharmacy workers could bring benefits to enhancing job satisfaction and workplace wellbeing