A DEM method for simulating rubber tyres

Recently, recycled rubber tyres were found to be an economical and environmental-friendly reinforcement material in geotechnical engineering. Although the use of rubber tyre-reinforced soil has become increasingly popular, there is still a lack of a robust and systematic method to model rubber tyres when using the discrete-element method (DEM) to investigate the stress-strain responses. In this paper, DEM rubber tyres are simulated by bonding regular-packed balls, and numerically tested under tensile force using the particle flow code in three dimensions. When comparing the effects of different packings on the sample, using Young's modulus and Poisson's ratio, it was found that only body-centred-cubic packing could achieve a Poisson's ratio of 0·5 representing no volume change during the deformation of rubber. The difference between uniaxial compression and tension simulations was also compared as well as the influences of particle overlapping, particle radius and sample aspect ratio on the mechanical response of the tyre model. Finally, the DEM parameters were set to match the experimental Young's modulus data. This proposed DEM rubber tyre strips model could be a basis to study other rubber reinforcements such as tyre chips and shreds, irregular rubber buffings and granulated rubber

Chemical Composition of Salvia plebeian R.Br. Essential Oil and its Larvicidal Activity against Aedes aegypti L

Purpose: To evaluate the larvicidal activity of the essential oil of Salvia plebeian R.Br. (Labiatae) aerial parts against the larvae of Aedes aegypti L.Methods: The essential oil of S. plebeian aerial parts was obtained by hydro-distillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The essential oil was evaluated for larvicidal activity using World Health Organization (WHO) procedures, against the fourth larvae of A. aegypti within 24 h, and activity was recorded for various concentrations of the ranging from 12.5 – 200.0 μg/mL.Results: A total of 33 components of the essential oil of S. plebeian were identified. The major compounds of the essential oil were caryophyllene oxide (15.54 %), γ-eudesmol (14.03 %), τ-cadinol (10.21 %), calamenene (9.63 %), copaene (5.70 %), γ-cadinene (5.30 %), cadalene (5.28 %), α- muurolene (5.19 %), ledol (5.14 %) and α-cadinol (5.08 %). The essential oil exhibited larvicidal activity against A. aegypti at a median lethal concentration (LC50) of 46.26 μg/mL.Conclusion: The findings indicate that the essential oil of S. plebeian aerial parts has potentials for use in the control of A. aegypti larvae and may be useful in the search for newer, safer and more effective natural compounds as larvicides.Keywords: Salvia plebeian, Essential oil, Larvicidal activity, Aedes aegypti, Caryophyllene oxide, γ- Eudesmol, τ-Cadinol, Calamenen

An affected pedigree member analysis of linkage between the dopamine D2 receptor gene Taql polymorphism and obesity and hypertension

BACKGROUND: Dopamine modulates a variety of physiological functions including natriuresis and satiety. We have previously reported that the TaqI polymorphism of the dopamine D2 receptor (DD2R) gene is associated with both blood pressure and obesity indices in a normoglycaemic Hong Kong Chinese population. In this study, we present evidence confirming the linkage between this gene polymorphism, obesity and hypertension. METHODS: Two hundred and seventy-four siblings from 96 normoglycaemic hypertensive families were recruited, including 133 who were hypertensive. Central obesity was defined as a waist-to-hip ratio of > or = 0.9 and > or = 0.85 in males and females, respectively, and was identified in 99 of the siblings. The DD2R gene TaqI polymorphism was identified with a polymerase chain reaction based restriction fragment length polymorphism protocol. The affected pedigree member (APM) linkage analysis (sib-pair program, version 0.99.9, by D.L. Duffy) was used to assess for linkage between this gene polymorphism, obesity and hypertension in 73 families with siblings discordant for hypertension. RESULTS: The A1 allele frequencies were similar in the 133 hypertensive, and 141 normotensive siblings, including the 99 centrally obese siblings at 0.431, 0.421 and 0.418, respectively. APM linkage analysis suggested that the DD2R gene TaqI polymorphism had evidence of linkage with blood pressure (T = -1.86, P = 0.013), as well as with obesity (T = -1.58, P = 0.007). CONCLUSION: Our data in normoglycaemic Hong Kong Chinese supports that the DD2R gene TaqI polymorphism is a marker associated with the pathogenesis of obesity and hypertension.postprin

Temperature and pressure behavior of the emission bands from Mn-, Cu-, and Eu-doped ZnS nanocrystals

The Mn-, Cu- and Eu-doped ZnS nanocrystals (NC) were analyzed for temeperature and pressure dependence of photoluminescence. The thermal quenching behavior of characteristic emission bands reflected nature of different transition mechanisms. The energies of Mn-orange and Eu-green emissions were observed to be weakly dependent on temperature. The results show strong interaction between excited state of Eu2+ ions and conduction band of ZnS which was responsible for positive pressure coefficient.published_or_final_versio

Artificial Topological Superconductor by the Proximity Effect

published_or_final_versio

Variation of structural vibration characteristics versus non-uniform temperature distribution

Author name used in this manuscript: You-Lin Xu2010-2011 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

A numerical study on dynamic shear rupture along frictional faults

The Wenchuan earthquake (Sichuan province, China, 2008) was caused by the dynamic rupture of Longmen Mountain fault. Such catastrophic disaster had led to a huge damage of life as well as major economic loss. The Longmen Mountain fault consisted of three faults with complex geometries, which gathered together as a main fault underground. The dynamic shear ruptures along the faults including bends and branches are frequently observed during earthquakes. In this study, the finite element method (FEM) is adopted to simulate the dynamic ruptures along both straight and branched faults, which are considered as frictional interfaces. A slip-weakening friction law is used to describe the interface behavior along faults. For the straight fault, the effects of pre-stress state and nucleation parameters on the dynamic shear rupture process are investigated; for the branched faults, the effects of pre-stress state and fault geometry on the rupture path selection are presented. The results are used to explain the rupture mechanism of Longmen Mountain fault during the earthquake

Ultra-high bandwidth quantum secured data transmission

Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment

Ageing memory and glassiness of a driven vortex system

Many systems in nature, glasses, interfaces and fractures being some examples, cannot equilibrate with their environment, which gives rise to novel and surprising behaviour such as memory effects, ageing and nonlinear dynamics. Unlike their equilibrated counterparts, the dynamics of out-of- equilibrium systems is generally too complex to be captured by simple macroscopic laws. Here we investigate a system that straddles the boundary between glass and crystal: a Bragg glass formed by vortices in a superconductor. We find that the response to an applied force evolves according to a stretched exponential, with the exponent reflecting the deviation from equilibrium. After the force is removed, the system ages with time and its subsequent response time scales linearly with its age (simple ageing), meaning that older systems are slower than younger ones. We show that simple ageing can occur naturally in the presence of sufficient quenched disorder. Moreover, the hierarchical distribution of timescales, arising when chunks of loose vortices cannot move before trapped ones become dislodged, leads to a stretched-exponential response.Comment: 16 pages, 5 figure

Genetic Diversity of Dahongjun, the Commercially Important “Big Red Mushroom” from Southern China

BACKGROUND: In southern China, a wild ectomycorrhizal mushroom commonly called "Dahongjun" or "Big Red Mushroom" by the local residents, has been harvested, consumed, and/or exported as an exotic food for many years. Although ecologically and economically important, very little is known about this mushroom, including its diversity and population structure. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we analyzed 122 samples from five local populations representing the known distribution ranges of this mushroom in southern China. We investigated the genetic diversity and geographic structure of this mushroom using sequences from four DNA fragments. Our analyses identified that this mushroom contained at least three divergent lineages: one corresponds to a recently described species Russula griseocarnosa from southern China and the remaining two likely represent two novel species. While these lineages were prominently structured geographically based on ITS sequences, evidence for ancient and/or recent gene flow was also identified within individual lineages. In addition, a local population from Ailaoshan in central Yunnan Province where 85 of our 122 specimens came from showed clear evidence of recombination. CONCLUSION AND SIGNIFICANCE: The ectomycorrhizal mushroom "Dahongjun" from southern China is a species complex with at least three divergent lineages. These lineages are largely geographically structured and there is evidence for recombination in nature. Our results indicate mature Dahongjun mushrooms with abundant basidiospores are important for the reproduction of this mushroom in nature and that individual populations of this species should be managed separately