4,180 research outputs found

    Heated Motorized Stage for Nanoscale Thin Film Deposition

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    ME450 Capstone Design and Manufacturing Experience: Fall 2015Thin film deposition is a technology of applying a very thin film of material onto a substrate surface to be coated, or onto a previously deposited coating to form layers. As a modified Atomic Layer Deposition (ALD) method, Spatial ALD greatly improves the efficiency of the process by separating the half-reactions spatially instead of through the use of purge steps in convectional ALD. This paper proposes the use of heated motorized stage as a research prototype to further study the effect of deposition conditions such as gap size, gap alignment and substrate temperature on the SALD coating results. This strategy utilized three stepper motors and high precision non-contact gap sensors to control gap alignment and gap size between the substrate and the depositor. The details of the involved methodology, engineering analysis, validation of the final design and the design critiques are discussed in this paper.http://deepblue.lib.umich.edu/bitstream/2027.42/117338/1/ME450-F15-Project19-FinalReport.pd

    Simple model for decay of superdeformed nuclei

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    Recent theoretical investigations of the decay mechanism out of a superdeformed nuclear band have yielded qualitatively different results, depending on the relative values of the relevant decay widths. We present a simple two-level model for the dynamics of the tunneling between the superdeformed and normal-deformed bands, which treats decay and tunneling processes on an equal footing. The previous theoretical results are shown to correspond to coherent and incoherent limits of the full tunneling dynamics. Our model accounts for experimental data in both the A~150 mass region, where the tunneling dynamics is coherent, and in the A~190 mass region, where the tunneling dynamics is incoherent.Comment: 4 page

    Spreading Width for Decay out of a Superdeformed Band

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    The attenuation factor F responsible for the decay out of a superdeformed (SD) band is calculated with the help of a statistical model. This factor is given by 1/F = (1 + Gamma(down) / Gamma(S)). Here, Gamma(S) is the width for the collective E2 transition within the superdeformed band, and Gamma(down) is the spreading width which describes the mixing between a state in the SD band and the normally deformed (ND) states of equal spin. The attenuation factor F is independent of the statistical E1 decay widths Gamma(N) of the ND states provided that the Gamma(N) are much larger than both Gamma(down) and Gamma(S). This condition is generically met. Previously measured values of F are used to determine Gamma(down).Comment: Submitted to Physical Review Letter

    Effect of different drying methods and solvent ratios on biological activities of Phyllanthus acidus extracts

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    The main purpose of this study was to evaluate the antioxidant and α-glucosidase inhibitory activities of Phyllanthus acidus. The P. acidus fruits were dried using three different methods, namely oven (OD), air (AD) and freeze (FD) dryings and extracted with ethanol at different ratios (50 and 100%). The proximate analysis and total phenolic content (TPC) as well as free radical scavenging and α-glucosidase inhibitory activities were determined. The proximate analysis of P. acidus fruit indicated that all the dried samples contained potential nutrient contents. The highest TPC value, α-glucosidase inhibitory and antioxidant activities were observed for 50% ethanolic extract from OD method with TPC value of 28.39 mg GAE/g dried extract, IC50 value of 12.394 μg/mL and 64.17% inhibition, respectively. The study revealed that phenolic compounds could be the main contributors to the antioxidant and α-glucosidase inhibitory activities based on the Pearson correlation coefficients with R values of 95.0 and 73.8%, respectively. The study could provide scientific evidence for some folk uses in the treatment of diseases related to the production of reactive oxygen species and oxidative stress

    Computation tools for the combat of cardiovascular heart disease

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    The paper discusses two potential applications of computational technologies to combat cardiovascular heart disease in Singapore. The first application involves the exploitation of neural networks for the risk prediction of coronary heart disease. The second application involves the potential integration of artificial intelligence and high performance modelling with clinical biology for the analysis and visualisation of atherosclerosis related structure. The implementation of these computation tools in phases constitutes initial efforts in the development of a digital clinical atherosclerosis laboratory to assist in the prevention and treatment of cardiovascular heart disease

    Genetic diversity affects seedling survival but not growth or seed germination in the Bornean endemic dipterocarp Parashorea tomentella

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    Background: Logging and habitat fragmentation of tropical rain forests may disrupt patterns of gene flow and genetic diversity. Consequently, inbreeding in tree populations may reduce fitness and increase extinction risks, especially among species that are predominantly outcrossing, dependent on biotic pollination and/or display limited seed dispersal such as species of the Dipterocarpaceae. Aims: To test the hypothesis that heterozygosity of individual progeny affects their likelihood of germination and the growth and survival of seedlings. Methods: Standardised measure of multilocus heterozygosity (sMLH) was estimated from seven microsatellite loci for individual progeny collected from 18 mother trees of the large dipterocarp Parashorea tomentella. The relationships among sMLH, germination and seedling growth and survival were determined for the progeny. Results: Seedling survival over 18 months increased with greater sMLH and fresh fruit weight. This result was expressed under all experimentally controlled combinations of light and nutrient availability in the nursery and in the shaded understorey of primary forest where survival overall was much lower than in the nursery. sMLH did not affect the probability of germination or seedling growth rate in any experimental treatment. Conclusions: These results provide evidence that reduced heterozygosity is associated with reduced seedling survival in a tropical forest tree species

    First report of citrus bent leaf viroid in Malaysia

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    Leaf samples of citrus species such as calamondin (Citrofortunella microcarpa), kaffir lime (Citrus hystrix), key lime (Citrus aurantifolia [C. aurantiifolia]), mandarin orange (Citrus reticulata), pomelo (Citrus maxima) and sweet orange (Citrus sinensis) with stunting, leaf yellowing and epinasty were collected from different states in Malaysia. The rootstocks of these samples were not known. Total nucleic acids were extracted from leaves around the tree canopy and tested by RT-PCR with two sets of primers, CBLV-CM/ CBLV-CP and the newly designed YI4F/YI4R. Altogether, 21 of 133 citrus samples were positive for Citrus bent leaf viroid (CBLVd). The resulting amplicons of 328 bp and 234 bp in size were cloned. Sequence analysis revealed 95-99% identity with CBLVd isolate Jp (accession No. AB006734), confirming the presence of CBLVd (KU194472, KX823338-KX823343) in the tested samples. No particular symptoms were observed in the test samples correlated with the presence of CBLVd, thus the observed symptoms may not be induced by this viroid. This is thought to be the first report of CBLVd in Malaysia
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