6,049 research outputs found
Trace element concentration in mango (Mangifera indica L.), seedless guava (Psidium guajava L.) and papaya (Carica papaya L.) grown on agricultural and ex-mining lands of Bidor, Perak
Fruits namely mango, papaya, and seedless guava grown on agricultural and ex-mining lands in Bidor were
sampled for analyse of heavy metal contamination. The concentration of mercury (Hg), lead (Pb), copper (Cu),
zinc (Zn), nickel (Ni), arsenic (As) and cadmium (Cd) in the fruits were analysed. The results showed that,
with the exception of Hg in mango and Pb in guava, fruits grown on agricultural land have higher levels of heavy
metals than those grown on ex-mining land. The concentration of heavy metal in all fruits of both soil types ranged from 0.06 to 0.55 mg kgI for Cd, 0.02 to 0.78 mg kgI for Hg, 0.63 to 8.71 mg kgI for Pb, 5.20 to 12.22
mg kgI for Zn, and 2.01 to 5.74 mg kgI for Cu. Both Cr and Ni were not detected in papaya grown on mine spoils, whilst As was not detected in all fruits grown on both types of soils. The findings indicate that all fruits contained unacceptably high levels of Hg and Pb. The probable causes of contamination are discussed. Further studies are required to investigate the cause of heavy metal contamination in these fruits
Highly Efficient Midinfrared On-Chip Electrical Generation of Graphene Plasmons by Inelastic Electron Tunneling Excitation
Inelastic electron tunneling provides a low-energy pathway for the excitation
of surface plasmons and light emission. We theoretically investigate tunnel
junctions based on metals and graphene. We show that graphene is potentially a
highly efficient material for tunneling excitation of plasmons because of its
narrow plasmon linewidths, strong emission, and large tunability in the
midinfrared wavelength regime. Compared to gold and silver, the enhancement can
be up to 10 times for similar wavelengths and up to 5 orders at their
respective plasmon operating wavelengths. Tunneling excitation of graphene
plasmons promises an efficient technology for on-chip electrical generation and
manipulation of plasmons for graphene-based optoelectronics and nanophotonic
integrated circuits.Comment: 12 pages, 7 figure
Sputter Deposition and Thallination of Ti-Ba-Ca-Cu-O Superconducting Thin Films
Thallination techniques used for the fabrication of sputter-deposited TI2Ba2CaCu 2Ox and TI2Ba2Ca2Cu3Ox superconducting thin films were investigated. Differences in elemental composition of precursor Ba-Ca-Cu-O sputtering targets were found to yield different superconducting phases. Thallination conditions which yielded transition temperatures as high as 122 K for samples annealed in air are described. Finally, reactive ion etching of films using a mixture of chlorine and argon gases is discussed
SphereFed: Hyperspherical Federated Learning
Federated Learning aims at training a global model from multiple
decentralized devices (i.e. clients) without exchanging their private local
data. A key challenge is the handling of non-i.i.d. (independent identically
distributed) data across multiple clients that may induce disparities of their
local features. We introduce the Hyperspherical Federated Learning (SphereFed)
framework to address the non-i.i.d. issue by constraining learned
representations of data points to be on a unit hypersphere shared by clients.
Specifically, all clients learn their local representations by minimizing the
loss with respect to a fixed classifier whose weights span the unit
hypersphere. After federated training in improving the global model, this
classifier is further calibrated with a closed-form solution by minimizing a
mean squared loss. We show that the calibration solution can be computed
efficiently and distributedly without direct access of local data. Extensive
experiments indicate that our SphereFed approach is able to improve the
accuracy of multiple existing federated learning algorithms by a considerable
margin (up to 6% on challenging datasets) with enhanced computation and
communication efficiency across datasets and model architectures.Comment: European Conference on Computer Vision 202
Graphene Transport at High Carrier Densities using a Polymer Electrolyte Gate
We report the study of graphene devices in Hall-bar geometry, gated with a
polymer electrolyte. High densities of 6 are
consistently reached, significantly higher than with conventional back-gating.
The mobility follows an inverse dependence on density, which can be correlated
to a dominant scattering from weak scatterers. Furthermore, our measurements
show a Bloch-Gr\"uneisen regime until 100 K (at 6.2 ),
consistent with an increase of the density. Ubiquitous in our experiments is a
small upturn in resistivity around 3 , whose origin is
discussed. We identify two potential causes for the upturn: the renormalization
of Fermi velocity and an electrochemically-enhanced scattering rate.Comment: 13 pages, 4 figures, Published Versio
Divergent LIN28-mRNA associations result in translational suppression upon the initiation of differentiation
LIN28 function is fundamental to the activity and behavior of human embryonic stem cells (hESCs) and induced pluripotent stem cells. Its main roles in these cell types are the regulation of translational efficiency and let-7 miRNA maturation. However, LIN28-associated mRNA cargo shifting and resultant regulation of translational efficiency upon the initiation of differentiation remain unknown. An RNA-immunoprecipitation and microarray analysis protocol, eRIP, that has high specificity and sensitivity was developed to test endogenous LIN28-associated mRNA cargo shifting. A combined eRIP and polysome analysis of early stage differentiation of hESCs with two distinct differentiation cues revealed close similarities between the dynamics of LIN28 association and translational modulation of genes involved in the Wnt signaling, cell cycle, RNA metabolism and proteasomal pathways. Our data demonstrate that change in translational efficiency is a major contributor to early stages of differentiation of hESCs, in which LIN28 plays a central role. This implies that eRIP analysis of LIN28-associated RNA cargoes may be used for rapid functional quality control of pluripotent stem cells under manufacture for therapeutic applications
Comparison of engagement and emotional responses of older and younger adults interacting with 3D cultural heritage artefacts on personal devices
The availability of advanced software and less expensive hardware allows museums to preserve and share artefacts digitally. As a result, museums are frequently making their collections accessible online as interactive, 3D models. This could lead to the unique situation of viewing the digital artefact before the physical artefact. Experiencing artefacts digitally outside of the museum on personal devices may affect the user's ability to emotionally connect to the artefacts. This study examines how two target populations of young adults (18–21 years) and the elderly (65 years and older) responded to seeing cultural heritage artefacts in three different modalities: augmented reality on a tablet, 3D models on a laptop, and then physical artefacts. Specifically, the time spent, enjoyment, and emotional responses were analysed. Results revealed that regardless of age, the digital modalities were enjoyable and encouraged emotional responses. Seeing the physical artefacts after the digital ones did not lessen their enjoyment or emotions felt. These findings aim to provide an insight into the effectiveness of 3D artefacts viewed on personal devices and artefacts shown outside of the museum for encouraging emotional responses from older and younger people
Onset of dielectric modes at 110K and 60K due to local lattice distortions in non-superconducting YBa_{2}Cu_{3}O_{6.0} crystals
We report the observation of two dielectric transitions at 110K and 60K in
the microwave response of non-superconducting YBa_{2}Cu_{3}O_{6.0} crystals.
The transitions are characterized by a change in polarizability and presence of
loss peaks, associated with overdamped dielectric modes. An explanation is
presented in terms of changes in polarizability of the apical O atoms in the
Ba-O layer, affected by lattice softening at 110K, due to change in buckling of
the Cu-O layer. The onset of another mode at 60K strongly suggests an
additional local lattice change at this temperature. Thus microwave dielectric
measurements are sensitive indicators of lattice softening which may be
relevant to superconductivity.Comment: 5 pages, 3 ps format figure
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