1,760 research outputs found
Enhanced compatibility between coconut fibers/PP via chemical modification for 3D printing
Aiming to produce high-quality bio-based 3D printed products, in this work, coconut fibers were chemical modified using caprolactone. Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic reasonance (NMR) confirmed the grafting of the hydroxyl groups present on the surface of the fibers with caprolactone units. Furthermore, from contact angle (CA) analyses, the higher hydrophobicity of fibers after chemical treatment was confirmed, which improved its affinity with PP. The enhanced filler/matrix compatibility was reflected on the mechanical performance and processability of the ensuing composites. The modified fibers derived composites showed higher stiffness and higher melting flow index (MFI), when compared to the untreated counterparts. The composites were used to produce 3D printed specimens. Smother filaments were obtained using modified fibers, which confirms the better compatibility of fibers/PP. The surface of the 3D printed composite specimen produced using treated fibers, presented smooth surface, similar to the PP. This observation highlights the enhancement of the 3D printing quality due to the chemical modification of fibers. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.publishe
Graded-bandgap AlGaAs solar cells for AlGaAs/Ge cascade cells
Some p/n graded-bandgap Al(x)Ga(1-x)As solar cells were fabricated and show AMO conversion efficiencies in excess of 15 percent without antireflection (AR) coatings. The emitters of these cells are graded between 0.008 is less than or equal to x is less than or equal to 0.02 during growth of 0.25 to 0.30 micron thick layers. The keys to achieving this performance were careful selection of organometallic sources and scrubbing oxygen and water vapor from the AsH3 source. Source selection and growth were optimized using time-resolved photoluminescence. Preliminary radiation-resistance measurements show AlGaAs cells degraded less than GaAs cells at high 1 MeV electron fluences, and AlGaAs cells grown on GaAs and Ge substrates degrade comparably
Heliophysics Event Knowledgebase for the Solar Dynamics Observatory and Beyond
The immense volume of data generated by the suite of instruments on SDO
requires new tools for efficient identifying and accessing data that is most
relevant to research investigations. We have developed the Heliophysics Events
Knowledgebase (HEK) to fill this need. The HEK system combines automated data
mining using feature-detection methods and high-performance visualization
systems for data markup. In addition, web services and clients are provided for
searching the resulting metadata, reviewing results, and efficiently accessing
the data. We review these components and present examples of their use with SDO
data.Comment: 17 pages, 4 figure
Experimental investigation of optical atom traps with a frequency jump
We study the evolution of a trapped atomic cloud subject to a trapping
frequency jump for two cases: stationary and moving center of mass. In the
first case, the frequency jump initiates oscillations in the cloud's momentum
and size. At certain times we find the temperature is significantly reduced.
When the oscillation amplitude becomes large enough, local density increases
induced by the anharmonicity of the trapping potential are observed. In the
second case, the oscillations are coupled to the center of mass motion through
the anharmonicity of the potential. This induces oscillations with even larger
amplitudes, enhancing the temperature reduction effects and leading to
nonisotropic expansion rates while expanding freely.Comment: 8 figures, Journal of Physics B: At. Mol. Op. Phy
The magnitude and characteristics of the population of cancer survivors: Using populationbased estimates of cancer prevalence to inform service planning for survivorship care
© 2014 Sharp et al. Background: Rising cancer incidence and survival mean that the number of cancer survivors is growing. Accumulating evidence suggests many survivors have long-term medical and supportive care needs, and that these needs vary by survivors' socio-demographic and clinical characteristics. To illustrate how cancer registry data may be useful in survivorship care service planning, we generated population-based estimates of cancer prevalence in Ireland and described socio-demographic and clinical characteristics of the survivor population. Methods: Details of people diagnosed with invasive cancer (ICD10 C00-C96) during 1994-2011, and who were still alive on 31/12/2011, were abstracted from the National Cancer Registry, and tabulated by cancer site, sex, current age, marital status, initial treatment, and time since diagnosis. Associations were investigated using chi-square tests. Results: After excluding non-melanoma skin cancers, 17-year cancer prevalence in Ireland was 112,610 (females: 58,054 (52%) males: 54,556 (48%)). The four most prevalent cancers among females were breast (26,066), colorectum (6,598), melanoma (4,593) and uterus (3,505) and among males were prostate (23,966), colorectum (8,207), lymphoma (3,236) and melanoma (2,774). At the end of 2011, 39% of female survivors were aged <60 and 35% were ≥70 compared to 25% and 46% of males (p < 0.001). More than half of survivors of bladder, colorectal and prostate cancer were ≥70. Cancers with the highest percentages of younger (<40) survivors were: testis (50%); leukaemia (females: 28%; males: 22%); cervix (20%); and lymphoma (females: 19%; males: 20%). Fewer female (57%) than male (64%) survivors were married but the percentage single was similar (17-18%). More female (25%) than male survivors (18%; p < 0.001) were ≥10 years from diagnosis. Overall, 69% of survivors had undergone cancer-directed surgery, and 39%, 32% and 18% had received radiotherapy, chemotherapy and hormone therapy, respectively. These frequencies were higher among females than males (surgery: 82%, 54%; radiotherapy: 42%, 35%; chemotherapy: 40%, 22%; hormone therapy: 23%, 13%). Conclusions: These results reveal the socio-demographic and clinical heterogeneity of the survivor population, and highlight groups which may have specific medical and supportive care needs. These types of population-based estimates may help decision-makers, planners and service providers to develop follow-up and after-care services to effectively meet survivors' needs
Electron irradiation effects on superconductivity in PdTe: an application of a generalized Anderson theorem
Low temperature ( 20~K) electron irradiation with 2.5 MeV relativistic
electrons was used to study the effect of controlled non-magnetic disorder on
the normal and superconducting properties of the type-II Dirac semimetal
PdTe. We report measurements of longitudinal and Hall resistivity, thermal
conductivity and London penetration depth using tunnel-diode resonator
technique for various irradiation doses. The normal state electrical
resistivity follows Matthiessen rule with an increase of the residual
resistivity at a rate of 0.77cm/. London penetration depth and thermal
conductivity results show that the superconducting state remains fully gapped.
The superconducting transition temperature is suppressed at a non-zero rate
that is about sixteen times slower than described by the Abrikosov-Gor'kov
dependence, applicable to magnetic impurity scattering in isotropic,
single-band -wave superconductors. To gain information about the gap
structure and symmetry of the pairing state, we perform a detailed analysis of
these experimental results based on insight from a generalized Anderson theorem
for multi-band superconductors. This imposes quantitative constraints on the
gap anisotropies for each of the possible pairing candidate states. We conclude
that the most likely pairing candidate is an unconventional
state. While we cannot exclude the conventional and the triplet
, we demonstrate that these states require additional assumptions about
the orbital structure of the disorder potential to be consistent with our
experimental results, e.g., a ratio of inter- to intra-band scattering for the
singlet state significantly larger than one. Due to the generality of our
theoretical framework, we think that it will also be useful for irradiation
studies in other spin-orbit-coupled multi-orbital systems.Comment: 22 pages, 12 figure
Effects of physical activity on the link between PGC-1a and FNDC5 in muscle, circulating Ιrisin and UCP1 of white adipocytes in humans: A systematic review
Background: Exercise may activate a brown adipose-like phenotype in white adipose tissue. The aim of this systematic review was to identify the effects of physical activity on the link between peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1a) and fibronectin type III domain-containing protein 5 (FNDC5) in muscle, circulating Irisin and uncoupling protein one (UCP1) of white adipocytes in humans. Methods: Two databases (PubMed 1966 to 08/2016 and EMBASE 1974 to 08/2016) were searched using an appropriate algorithm. We included articles that examined physical activity and/or exercise in humans that met the following criteria: a) PGC-1a in conjunction with FNDC5 measurements, and b) FNDC5 and/or circulating Irisin and/or UCP1 levels in white adipocytes. Results: We included 51 studies (12 randomised controlled trials) with 2474 participants. Out of the 51 studies, 16 examined PGC-1a and FNDC5 in response to exercise, and only four found increases in both PGC-1a and FNDC5 mRNA and one showed increased FNDC5 mRNA. In total, 22 out of 45 studies that examined circulating Irisin in response to exercise showed increased concentrations when ELISA techniques were used; two studies also revealed increased Irisin levels measured via mass spectrometry. Three studies showed a positive association of circulating Irisin with physical activity levels. One study found no exercise effects on UCP1 mRNA in white adipocytes. Conclusions: The effects of physical activity on the link between PGC-1a, FNDC5 mRNA in muscle and UCP1 in white human adipocytes has attracted little scientific attention. Current methods for Irisin identification lack precision and, therefore, the existing evidence does not allow for conclusions to be made regarding Irisin responses to physical activity. We found a contrast between standardised review methods and accuracy of the measurements used. This should be considered in future systematic reviews.PCD and ADF were supported by the European Union 7th Framework Programme [FP7-PEOPLE-2012-IRSES (FUEGO grant no. 612547), and FP7-PEOPLE-2013-IRSES (U-GENE grant no. 319010)]. PS was supported by the Swedish Federal Government under the LUA/ALF agreement (grant no. ALFGBG-431481)
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