2,491 research outputs found
Low temperature fullerene encapsulation in single wall carbon nanotubes: synthesis of N@C@SWCNT
High filling of single wall carbon nanotubes (SWCNT) with C and
C fullerenes in solvent is reported at temperatures as low as 69
C. A 2 hour long refluxing in n-hexane of the mixture of the fullerene
and SWCNT results in a high yield of C,C@SWCNT, fullerene peapod,
material. The peapod filling is characterized by TEM, Raman and electron energy
loss spectroscopy and X-ray scattering. We applied the method to synthesize the
temperature sensitive (N@C:C)@SWCNT as proved by electron spin
resonance spectroscopy. The solvent prepared peapod samples can be transformed
to double walled nanotubes enabling a high yield and industrially scalable
production of DWCNT
Fear for manufacturing? China and the future of industry in Brazil and Latin America
There has been considerable concern in Latin America over the implications of increased competition from China for local industry. These concerns include the possibility of "deindustrialization," the increased "primarization" of the region's exports and the difficulties of upgrading manufactured exports into higher technology products. This article examines the impact of Chinese competition both in the domestic market and in export markets on Brazilian industry. It documents the increased penetration of Chinese manufactures in the Brazilian market and the way in which Brazilian exports have lost market share to China in the US, European Union and four Latin American countries. Brazil, because of its more developed and locally integrated industrial sector, is not typical of other Latin American countries and the article also discusses the relevance of the Brazilian experience for the region as a whole
The study of Seyfert 2 galaxies with and without infrared broad lines
From the literature, we construct from literature a sample of 25 Seyfert 2
galaxies (S2s) with a broad line region detected in near infrared spectroscopy
and 29 with NIR BLR which was detected. We find no significant difference
between the nuclei luminosity (extinction-corrected [OIII]~5007) and infrared
color between the two populations, suggesting that the
non-detections of NIR BLR could not be due to low AGN luminosity or
contamination from the host galaxy. As expected, we find significantly lower
X-ray obscurations in Seyfert 2s with NIR BLR detection, supporting the
unification scheme. However, such a scheme was challenged by the detection of
NIR BLR in heavily X-ray obscured sources, especially in six of them with
Compton-thick X-ray obscuration. The discrepancy could be solved by the clumpy
torus model and we propose a toy model demonstrating that IR-thin X-ray-thick
S2s could be viewed at intermediate inclinations, and compared with those
IR-thick X-ray-thick S2s. We note that two of the IR-thin X-ray-thick S2s (NGC
1386 and NGC 7674) experienced X-ray transitions, i.e. from Compton-thin to
Compton-thick appearance or vice versa based on previous X-ray observations,
suggesting that X-ray transitions could be common in this special class of
objects
The future of wellness tourism after COVID-19
The tourism industry has drastically reduced its activity since the emergence of the COVID-19 pandemic, yet there has been an undeniable rise in demand for wellness tourism which now represents one of the fastest growing tourism market segments globally. Admittedly, while the COVID-19 pandemic has delayed the forecasted wellness tourism growth trend, this segment has stood fast at USD 4.4 trillion in 2020 while global GDP declined by 2.8%. In 2020, the wellness tourism market was valued at USD 436 billion, projected to rise to USD 816 billion by 2022 with more than 1.2 billion trips being realised and anticipated growth estimated at USD 1.0 trillion by 2025. The main purpose of this study is to ascertain the future trends of wellness tourism, and to investigate the extent to which this upward growth trend can be sustainably maintained post COVID-19. A qualitative structured interview methodology was employed using email interviews comprising six pre-determined questions with three expert wellness tourism participants. These expert interviewees were based in countries that were severely impacted by COVID-19, namely Brazil, USA, and Portugal. NVivo Nudist was used to analyse the primary data collected. In validating previous research findings, this study indicates that despite the challenges facing the sector, upward growth patterns in wellness tourism will continue beyond the COVID-19 pandemic
Multidimensional Dynamics of the Proteome in the Neurodegenerative and Aging Mammalian Brain
Neurodegenerative diseases are characterized by the abnormal accumulation of aggregated proteins in the brain. Using in vivo pulse isotope labeling, we screened the proteome for changes in protein turnover and abundance in multiple mouse models of neurodegeneration. These data suggest that the disease state of pathologically affected tissue is characterized by a proteome-wide increase in protein turnover and repair. In contrast, in healthy wild-type mice, aging in the mammalian brain is associated with a global slowdown in protein turnover.Peer reviewe
Bang-bang control of fullerene qubits using ultra-fast phase gates
Quantum mechanics permits an entity, such as an atom, to exist in a
superposition of multiple states simultaneously. Quantum information processing
(QIP) harnesses this profound phenomenon to manipulate information in radically
new ways. A fundamental challenge in all QIP technologies is the corruption of
superposition in a quantum bit (qubit) through interaction with its
environment. Quantum bang-bang control provides a solution by repeatedly
applying `kicks' to a qubit, thus disrupting an environmental interaction.
However, the speed and precision required for the kick operations has presented
an obstacle to experimental realization. Here we demonstrate a phase gate of
unprecedented speed on a nuclear spin qubit in a fullerene molecule (N@C60),
and use it to bang-bang decouple the qubit from a strong environmental
interaction. We can thus trap the qubit in closed cycles on the Bloch sphere,
or lock it in a given state for an arbitrary period. Our procedure uses
operations on a second qubit, an electron spin, in order to generate an
arbitrary phase on the nuclear qubit. We anticipate the approach will be vital
for QIP technologies, especially at the molecular scale where other strategies,
such as electrode switching, are unfeasible
Classification of patients with knee osteoarthritis in clinical phenotypes: data from the osteoarthritis initiative
<div><p>Objectives</p><p>The existence of phenotypes has been hypothesized to explain the large heterogeneity characterizing the knee osteoarthritis. In a previous systematic review of the literature, six main phenotypes were identified: Minimal Joint Disease (MJD), Malaligned Biomechanical (MB), Chronic Pain (CP), Inflammatory (I), Metabolic Syndrome (MS) and Bone and Cartilage Metabolism (BCM). The purpose of this study was to classify a sample of individuals with knee osteoarthritis (KOA) into pre-defined groups characterized by specific variables that can be linked to different disease mechanisms, and compare these phenotypes for demographic and health outcomes.</p><p>Methods</p><p>599 patients were selected from the OAI database FNIH at 24 months’ time to conduct the study. For each phenotype, cut offs of key variables were identified matching the results from previous studies in the field and the data available for the sample. The selection process consisted of 3 steps. At the end of each step, the subjects classified were excluded from the further classification stages. Patients meeting the criteria for more than one phenotype were classified separately into a ‘complex KOA’ group.</p><p>Results</p><p>Phenotype allocation (including complex KOA) was successful for 84% of cases with an overlap of 20%. Disease duration was shorter in the MJD while the CP phenotype included a larger number of Women (81%). A significant effect of phenotypes on WOMAC pain (F = 16.736 p <0.001) and WOMAC physical function (F = 14.676, p < 0.001) was identified after controlling for disease duration.</p><p>Conclusion</p><p>This study signifies the feasibility of a classification of KOA subjects in distinct phenotypes based on subgroup-specific characteristics.</p></div
Tool selection and the ventral‐dorsal organization of tool‐related knowledge
Tool selection is a cognitive process necessary for tool use, and may rely on distinct knowledge under different conditions. This fMRI experiment was designed to identify neural substrates mediating tool selection under different conditions. Participants performed a picture‐matching task that presented a recipient object and an action‐goal, and required the selection of the best tool object from among four candidates. Some trials allowed selection of the prototypical tool, whereas others forced selection of either a functionally substitutable or impossible tool. Statistical contrasts revealed significantly different activation between Proto and Sub conditions in frontal, parietal, and temporal lobes. The middle temporal gyrus (MTG) bilaterally, and the right posterior cingulate were more strongly activated by prototypical tool selection, and left inferior parietal lobule (IPL), intraparietal sulcus (IPS), middle frontal gyrus, and precuneus were more strongly activated when selecting substitutable objects. These findings are concordant with previous neuroimaging studies of tool use knowledge in demonstrating that activation of the MTG represents functional knowledge for conventional tool usage, and activation of the IPL/IPS supports action (i.e., praxic) knowledge representations. These results contribute to the literature that dissociates the roles of ventral and dorsal streams in tool‐related knowledge and behavior, and emphasize the role of the left hemisphere for processing goal‐directed object interactions
The stellar masses and specific star-formation rates of submillimetre galaxies
Establishing the stellar masses (M*), and hence specific star-formation rates
(sSFRs) of submillimetre galaxies (SMGs) is crucial for determining their role
in the cosmic galaxy/star formation. However, there is as yet no consensus over
the typical M* of SMGs. Specifically, even for the same set of SMGs, the
reported average M* have ranged over an order of magnitude, from ~5x10^10 Mo to
~5x10^11 Mo. Here we study how different methods of analysis can lead to such
widely varying results. We find that, contrary to recent claims in the
literature, potential contamination of IRAC 3-8 um photometry from hot dust
associated with an active nucleus is not the origin of the published
discrepancies in derived M*. Instead, we expose in detail how inferred M*
depends on assumptions made in the photometric fitting, and quantify the
individual and cumulative effects of different choices of initial mass
function, different brands of evolutionary synthesis models, and different
forms of assumed star-formation history. We review current observational
evidence for and against these alternatives as well as clues from the
hydrodynamical simulations, and conclude that, for the most justifiable choices
of these model inputs, the average M* of SMGs is ~2x10^11 Mo. We also confirm
that this number is perfectly reasonable in the light of the latest
measurements of their dynamical masses, and the evolving M* function of the
overall galaxy population. M* of this order imply that the average sSFR of SMGs
is comparable to that of other star-forming galaxies at z>2, at 2-3 Gyr^-1.
This supports the view that, while rare outliers may be found at any M*, most
SMGs simply form the top end of the main-sequence of star-forming galaxies at
these redshifts. Conversely, this argues strongly against the viewpoint that
SMGs are extreme pathological objects, of little relevance in the cosmic
history of star-formation.Comment: Accepted to A&A. 13 pages, 5 figures, 3 tables. Main changes: 1)
investigation that the main-sequence does not change the location as much as
SMGs when changing SFHs; 2) a new table added with all stellar mass estimates
for individual SMGs (machine-readable version in the source file). V3:
missing references adde
γ-Glutamylcysteine detoxifies reactive oxygen species by acting as glutathione peroxidase-1 cofactor
Reactive oxygen species regulate redox-signaling processes, but in excess they can cause cell damage, hence underlying the aetiology of several neurological diseases. Through its ability to down modulate reactive oxygen species, glutathione is considered an essential thiol-antioxidant derivative, yet under certain circumstances it is dispensable for cell growth and redox control. Here we show, by directing the biosynthesis of γ-glutamylcysteine—the immediate glutathione precursor—to mitochondria, that it efficiently detoxifies hydrogen peroxide and superoxide anion, regardless of cellular glutathione concentrations. Knocking down glutathione peroxidase-1 drastically increases superoxide anion in cells synthesizing mitochondrial γ-glutamylcysteine. In vitro, γ-glutamylcysteine is as efficient as glutathione in disposing of hydrogen peroxide by glutathione peroxidase-1. In primary neurons, endogenously synthesized γ-glutamylcysteine fully prevents apoptotic death in several neurotoxic paradigms and, in an in vivo mouse model of neurodegeneration, γ-glutamylcysteine protects against neuronal loss and motor impairment. Thus, γ-glutamylcysteine takes over the antioxidant and neuroprotective functions of glutathione by acting as glutathione peroxidase-1 cofactor
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