2,189 research outputs found
Influence of temperature and sliding speed on the subsurface microstructure evolution of EN AW-6060 under sticking friction conditions
No full textThis article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in AIP Conference Proceedings 1896, 140012 (2017) and may be found at https://doi.org/10.1063/1.5008168.The microstructure evolution of the friction boundary layer of the aluminum alloy EN AW-6060 was investigated. Sticking friction tests at different temperatures and sliding speeds were carried out. A severe deformation below the friction surface was observed by means of LOM and EBSD mapping. Thus, the thickness variation and the grain structure of the high deformation zone could be described. Fibrous structure was observed at 300 °C and 400 °C, while equiaxed grains with high misorientation angle (>15°) were generated at higher temperatures. Additionally, abnormal grain growth and coarse grains were detected at high sliding speeds (10 mm/s, 42 mm/s) at 450°C and 500 °C respectively
Tyrosine phosphorylation of myosin heavy chain during skeletal muscle differentiation: an integrated bioinformatics approach
No full textBackground: Previously it has been shown that insulin-mediated tyrosine phosphorylation of myosin heavy chain is concomitant with enhanced association of C-terminal SRC kinase during skeletal muscle differentiation. We sought to identify putative site(s) for this phosphorylation event.Results: A combined bioinformatics approach of motif prediction and evolutionary and structural analyses identified tyrosines163 and 1856 of the skeletal muscle heavy chain as the leading candidate for the sites of insulin-mediated tyrosine phosphorylation.Conclusion: Our work is suggestive that tyrosine phosphorylation of myosin heavy chain, whether in skeletal muscle or in platelets, is a significant event that may initiate cytoskeletal reorganization of muscle cells and platelets. Our studies provide a good starting point for further functional analysis of MHC phosphor-signalling events within different cells.<br/
Author-Suggested, Weighted Citation Index: A Novel Approach for Determining the Contribution of Individual Researchers
No full textA novel scientometric index, named ‘author-suggested, weighted citation index’ (Aw-index) is proposed to indicate the scientific contribution of any individual researcher. For calculation of the Aw-index, it is suggested that during the submission of a scholarly article, the corresponding author would provide a statement, agreed upon by all the authors, containing weightage factors against each author of the article. The author who contributed more to the article would secure a higher weightage factor. The summation of the weightage factors of all the authors of an article should be unity. The citation points a researcher receives from a scholarly publication is the product of his/her weightage factor for that article and the total number of citations of the article. The Aw-index of any individual researcher is the summation of the citation points he/she receives for all his/her publications as an author. The Aw-index provides the opportunity to the group of authors of a multi-authored article to determine the quantum of partial citations to be attributed to each of them. Through an illustrative example, a comparison of the proposed index with the major scientometric indexes is presented to highlight the advantages of the Aw-index
Ecology of A.carbonarius and ochratoxin A production in vine fruits and control in the production chain
No full textThis study examined black aspergilli, especially A. carbonarius and A. niger and
ochratoxin A (OTA) contamination of grapes, during drying and industrial processing
of dried vine fruits. This was complemented by studies on potential control using
preservatives and physical factors such as modified atmospheres. Fungal population
kinetics were determined in relation to grapes at harvest, and during drying at three
different altitudes (sea level: 0-200 m; medium level: 250-500 m; high level: >500 m)
in two seasons. At pre-harvest, A. niger aggregate species were the predominant
fungal species while A. carbonarius was occasionally isolated, in both years studied.
Both altitude and bunch position affected black aspergilli population dynamics.
Overall, they were increased during drying. However, both black aspergilli groups
were mostly isolated, at low and medium altitudes (<500 m). OTA contamination
was influenced by bunch position, although altitude did not significantly influenced
amounts. The fungal biodiversity was decreased during sun-drying of sultanas. The
widest diversity of species occurred at the sea level. However, A. niger aggregate,
were dominant during drying. Time of drying and altitude significantly influenced
fungal loads of black aspergilli. In contrast, OTA production (ca 0.001 - 0.0025 μg g
-
1
) was not significantly influenced by altitude and drying time. Shannon Index of
Biodiversity (H), for pre-harvest and pos-harvest studies, was determined for the first
time.
A. niger aggregate (ca 5.0 Log10 CFUs g
-1
) was predominant during industrial
processing, while A. carbonarius was only isolated at low levels (1.5-2.0 Log10 CFUs
g
-1
). Heat treatment (up to 90
o
C) appeared to be the key-procedure for the
elimination of fungal populations. In the contrary, SO2 treatment did not statistically
alter fungal population dynamics. OTA contamination was not significantly affected
by industrial processing.
In vitro studies conducted on both White Grape Juice Medium (WGJM) and in
sultanas with strains of A. carbonarius originated from Cretan sultanas and compared with a strain isolated from Italian wine grapes. They examined the impact of sodium
metabisulphite (NaMBS), elevated CO2 (up to 50%) concentrations and aw levels, on
black aspergilli spore germination, growth and OTA production. Moreover, fungal
interactions in vitro and in situ were also investigated.
In general, spore germination occurred over a wide range of sodium metabisulphite
concentrations, although germ tube extension was significantly controlled. At ≥ 750
mg L
-1
NaMBS, no spore germination was observed while both mycelial growth and
OTA production were completely inhibited. Medium concentrations of NaMBS (≤
250 mg L
-1
) enabled optimum spore germination, growth and OTA production (x
0.965 aw). The efficacy of controlled atmospheres x aw showed that there was very
little inhibitory effect on spore germination. However, both germ tube extension and
fungal growth were inhibited by 50% CO2. After 10 days, growth was not as
effectively controlled. Aw had a bigger effect on OTA production than modified
atmospheres. In situ experiments on sultanas confirmed these results. Competition
and dominance of A. carbonarius over other fungal species showed that aw and
temperature influenced Indices of Dominance and OTA production. In vitro and in
situ, OTA production by A. carbonarius was significantly influenced by the fungal
competitor used
Influence of Process Parameters on the Quality of Aluminium Alloy EN AW 7075 Using Selective Laser Melting (SLM)
No full textAbstractSelective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be manufactured with high accuracy and little post processing. Currently, different steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop the SLM process for the wide used aluminium alloy EN AW 7075. Before process development, the gas-atomized powder material was characterized in terms of statistical distribution: size and shape. A wide range of process parameters were selected to optimize the process in terms of optimum volume density. The investigations resulted in a relative density of over 99%. However, all laser-melted parts exhibit hot cracks which typically appear in aluminium alloy EN AW 7075 during the welding process. Furthermore the influence of processing parameters on the chemical composition of the selected alloy was determined
Zhedanov's Algebra AW(3) and the Double Affine Hecke Algebra in the Rank One Case. II. The Spherical Subalgebra
No full textThis paper builds on the previous paper by the author, where a relationship between Zhedanov's algebra AW(3) and the double affine Hecke algebra (DAHA) corresponding to the Askey-Wilson polynomials was established. It is shown here that the spherical subalgebra of this DAHA is isomorphic to AW(3) with an additional relation that the Casimir operator equals an explicit constant. A similar result with q-shifted parameters holds for the antispherical subalgebra. Some theorems on centralizers and centers for the algebras under consideration will finally be proved as corollaries of the characterization of the spherical and antispherical subalgebra
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Extensions and amplifications of a traffic model of Aw and Rascle
No full textIn a recent paper [1] Aw and Rascle introduced a new model of traffic on a uni-directional highway. Here the author studies an extension of this model, one which accounts for drivers attempting to travel at their maximum allowable speed. The author looks at a Lagrangian reformulation of this problem; a formulation that leads to an effective computational algorithm for solving the resulting system. He also investigates approximation scheme introduced by Dafermos [5] for scalar conservation laws and demonstrates that this Dafermos scheme works well on this 2 x 2 system
Automating the determination of wave speed using the pu-loop method
No full textThe PU-loop (pressure-velocity loop) is a method for determining wave speed and relies on the linear relationship between the pressure and velocity in the absence of reflected waves. This linearity of the PU-loop during early systole, which is directly related to wave speed, has always been established by eye. This paper presents a new technique that establishes this linearity and thus determining wave speed online. Pressure and flow were measured in the ascending aorta of 11 anesthetised dogs. The slope of the PU-loop, indicating wave speed was determined by eye and by using the new technique. The difference between the slopes of the two methods is in the order of 3%. The new technique is convenient and allows for the online assessment of wave speed, which could be used as a bedside tool for the assessment of arterial compliance
Rainbow Arithmetic Progressions
No full textIn this paper, we investigate the anti-Ramsey (more precisely, anti-van der Waerden) properties of arithmetic progressions. For positive integers n and k, the expression aw([n]; k) denotes the smallest number of colors with which the integers f1; : : : ; ng can be colored and still guarantee there is a rainbow arithmetic progression of length k. We establish that aw([n]; 3) = (log n) and aw([n]; k) = n1o(1) for k 4. For positive integers n and k, the expression aw(Zn; k) denotes the smallest number of colors with which elements of the cyclic group of order n can be colored and still guarantee there is a rainbow arithmetic progression of length k. In this setting, arithmetic progressions can \wrap around," and aw(Zn; 3) behaves quite differently from aw([n]; 3), depending on the divisibility of n. As shown in [Jungic et al., Combin. Probab. Comput., 2003], aw(Z2m; 3) = 3 for any positive integer m. We establish that aw(Zn; 3) can be computed from knowledge of aw(Zp; 3) for all of the prime factors p of n. However, for k 4, the behavior is similar to the previous case, that is, aw(Zn; k) = n1o(1).This is a manuscript of an article published as Butler, Steve, Craig Erickson, Leslie Hogben, Kirsten Hogenson, Lucas Kramer, Richard Kramer, Jephian C. H. Lin, Ryan R. Martin, Derrick Stolee, Nathan Warnberg, and Michael Young. "Rainbow Arithmetic Progressions." Journal of Combinatorics 7, no. 4 (2016): 595-626. DOI: 10.4310/JOC.2016.v7.n4.a3. Posted with permission.</p
Simultaneous three-dimensional printing and frontal polymerization of dicyclopentadiene resin
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Previous issue date: 2019-04-26Three-dimensional (3D) printing has widespread uses across many industries due to its versatility and capabilities. However, freeform fabrication of thermoset polymers remains a technical challenge. This thesis combines 3D printing with frontal polymerization (FP) — a method to rapidly cure resin — for curing filaments in tandem with the printing process. A partially cured dicyclopentadiene (DCPD) resin was developed into a printing ink. Critical rheological characteristics were identified, and DCPD inks of varying incubation times were screened to find the most suitable properties. Results of the rheological study indicate that 90 minutes of incubation time resulted in optimum print behavior. Problems associated with FP were effectively tackled through temperature control across the printing setup. In situ infrared images showed an exothermic reaction front propagating during the print process, giving evidence of in situ polymerization. The optimized technique produced one-dimensional, two-dimensional and 3D freeform prints with excellent fidelity. A self-equilibrating behavior was identified in the reaction front, such that the front autonomously tune its speed to the programmed print speed. This phenomenon autonomously controls the viscoelastic bridge length, Lb, and inevitably curbs deformations to achieve high print fidelity.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Jia En Aw, accepted the attached license on 2019-04-26 at 14:07.The student, Jia En Aw, submitted this Thesis for approval on 2019-04-26 at 14:16.This Thesis was approved for publication on 2019-04-26 at 14:46.DSpace SAF Submission Ingestion Package generated from Vireo submission #13952 on 2019-08-22 at 16:24:04Embargo set by: Seth Robbins for item 112399
Lift date: 2021-08-23T20:48:32Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 112399 on 2021-08-24T09:15:35Z
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