5,743 research outputs found
Zinc(II) coordination polymers with pseudopeptidic ligands
Two new phenyl-bridged pseudopeptidic ligands have been prepared and structurally characterised. The nature of the ligandsâ substituents play an important role in the nature of the solid state structure yielding either hydrogen bonded linked sheets of molecules or infinite hydrogen bonded networks. Both these ligands were reacted with a range of zinc(II) salts with the aim of synthesising coordination polymers and networks and exploring the role that anions could play in determining the final structure. The crystal structures of four of these systems (with ZnSO4 and ZnBr2) were determined; in one case, a 3D coordination network was obtained where zincâligand coordination bonds generated the 3D arrangements. Three other 3D networks were obtained by anion-mediated hydrogen bonding of coordination 1D chains or 2D sheets. These four very different structures highlight the important role played by the ligandsâ substituents and the counteranions present in the system
Genetic predisposition to colorectal cancer: syndromes, genes, classification of genetic variants and implications for precision medicine
This article reviews genes and syndromes associated with predisposition to colorectal cancer (CRC), with an overview of gene variant classification. We include updates on the application of preventive and therapeutic measures, focusing on the use of non-steroidal anti-inflammatory drugs (NSAIDs) and immunotherapy. Germline pathogenic variants in genes conferring high or moderate risk to cancer are detected in 6-10% of all CRCs and 20% of those diagnosed before age 50. CRC syndromes can be subdivided into nonpolyposis and polyposis entities, the most common of which are Lynch syndrome and familial adenomatous polyposis, respectively. In addition to known and novel genes associated with highly penetrant CRC risk, identification of pathogenic germline variants in genes associated with moderate-penetrance cancer risk and/or hereditary cancer syndromes not traditionally linked to CRC may have an impact on genetic testing, counseling, and surveillance. The use of multigene panels in genetic testing has exposed challenges in the classification of variants of uncertain significance. We provide an overview of the main classification systems and strategies for improving these. Finally, we highlight approaches for integrating chemoprevention in the care of individuals with genetic predisposition to CRC and use of targeted agents and immunotherapy for treatment of mismatch repair-deficient and hypermutant tumors. Copyright (c) 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd
Treatment and energy valorization of residual glycerol in a perfectly mixed batch reactor
The anaerobic digestion of crude glycerol from the production of
biodiesel is an alternative that has been studied for its valorization
through the production of methane. The high organic load (1800 g
COD.L-1) of crude glycerol can cause kinetic stress, which results in
an inhibition of methanogenic microorganisms. To circumvent the
problem, an alternative is the prior use of ultrasonic energy and the
use of microorganisms such as Aspergillus niger and Escherichia
coli. Ultrasound promotes the breakdown of the cell wall and
membrane, releasing intracellular material that favors biodigestion.
In addition, such microorganisms can produce lipases capable of
degrading other impurities contained in the residual glycerol, such as
long chain fatty acids. The aim of this study is to improve the
anaerobic digestion of glycerol through physical (ultrasound) and
biological (A. niger and E. coli) pretreatments. The results indicate
that the use of ultrasound improved methane generation by 23% for a
lower concentration of glycerol (2%). There were also improvements
from the use of A. niger in 1.7% glycerol. For the concentration of
3.2% glycerol and the use of E. coli in all experiments caused
inhibition of methanogenic microorganisms.info:eu-repo/semantics/publishedVersio
Contrasting seismic risk for Santiago, Chile, from near-field and distant earthquake sources
More than half of all the people in the world now live in dense urban centres. The rapid expansion of cities, particularly in low-income nations, has enabled the economic and social development of millions of people. However, many of these cities are located near active tectonic faults that have not produced an earthquake in recent memory, raising the risk of losing hard-earned progress through a devastating earthquake. In this paper we explore the possible impact that earthquakes can have on the city of Santiago in Chile from various potential near-field and distant earthquake sources. We use high-resolution stereo satellite imagery and imagery-derived digital elevation models to accurately map the trace of the San RamĂłn Fault, a recently recognised active fault located along the eastern margins of the city. We use scenario-based seismic-risk analysis to compare and contrast the estimated damage and losses to the city from several potential earthquake sources and one past event, comprising (i) rupture of the San RamĂłn Fault, (ii) a hypothesised buried shallow fault beneath the centre of the city, (iii) a deep intra-slab fault, and (iv) the 2010 Mw 8.8 Maule earthquake. We find that there is a strong magnitudeâdistance trade-off in terms of damage and losses to the city, with smaller magnitude earthquakes in the magnitude range of 6â7.5 on more local faults producing 9 to 17 times more damage to the city and estimated fatalities compared to the great magnitude 8+ earthquakes located offshore in the subduction zone. Our calculations for this part of Chile show that unreinforced-masonry structures are the most vulnerable to these types of earthquake shaking. We identify particularly vulnerable districts, such as ĂuĂąoa, Santiago, and Providencia, where targeted retrofitting campaigns would be most effective at reducing potential economic and human losses. Due to the potency of near-field earthquake sources demonstrated here, our work highlights the importance of also identifying and considering proximal minor active faults for cities in seismic zones globally in addition to the more major and distant large fault zones that are typically focussed on in the assessment of hazard
Pre-COVID-19 Social Determinants of Health Among Mexican Migrants in Los Angeles and New York City and Their Increased Vulnerability to Unfavorable Health Outcomes During the COVID-19 Pandemic
COVID-19 has disproportionally affected underrepresented minorities (URM) and low-income immigrants in the United States. The aim of the study is to examine the underlying vulnerabilities of Mexican immigrants in New York City (NYC) and Los Angeles (LA), its correspondence with area-level COVID-19 morbidity and mortality, and to document the role of trusted and culturally sensitive services offered during the pandemic through the Ventanillas de Salud (i.e. VDS, Health Windows) program. The study uses a mixed-methods approach including a cross-sectional survey of Mexican immigrants in LA and NYC collected in the Mexican Consulates at the onset of the pandemic, complemented with a georeferencing analysis and key informant interviews. Data suggested an increased vulnerability to COVID-19 given participants reported health status, health care profile and place of residence, which coincided with the georeferencing analysis. The key informant interviews confirmed the vulnerability of this population and the supporting role of VDS in helping immigrants navigate health systems and disseminate health information. Mexican immigrants had an increased vulnerability to COVID-19 at the individual, geographic and systemic levels. Trusted and culturally sensitive services are needed to overcome some of the barriers and risk factors that increase the vulnerability of URM and immigrant populations to COVID-19
Estudio comparativo de las epidermis foliares de las licopodiaceas ibericas I. Estomas
Se realiza un estudio comparativo de los estomas, tanto de los esporofilos como de los trofofilos, de Huperzia selago (L.) Bernh ex Schrank & Mart., Lycopodium annotinum L.,Lycopodium clavatum L., Diphasiastrum alpinum (L.) Holub y Lycopodiella inundata (L.) Holub aportando datos sobre la localizaciĂłn de los estomas en la lĂĄmina foliar, su distribuciĂłn y nĂşmero.A comparative study of stomates was made, both in sporophylles and trophophylles of Huperzia selago (L.) Bernh ex Schrank & Mart.,Lycopodium annotinum L. ,Lycopodium clavatum L.,Diphasiastrum alpinum (L.) Holub and Lycopodiella inundata (L.) Holub, giving new data about the localization of stomates on the foliar lamina, their distribution and number
On the Renormalizability of Noncommutative U(1) Gauge Theory - an Algebraic Approach
We investigate the quantum effects of the nonlocal gauge invariant operator
in the
noncommutative U(1) action and its consequences to the infrared sector of the
theory. Nonlocal operators of such kind were proposed to solve the infrared
problem of the noncommutative gauge theories evading the questions on the
explicit breaking of the Lorentz invariance. More recently, a first step in the
localization of this operator was accomplished by means of the introduction of
an extra tensorial matter field, and the first loop analysis was carried out
. We will complete this localization
avoiding the introduction of new degrees of freedom beyond those of the
original action by using only BRST doublets. This will allow us to make a
complete BRST algebraic study of the renormalizability of the theory, following
Zwanziger's method of localization of nonlocal operators in QFT.Comment: standard Latex no figures, version2 accepted in J. Phys A: Math Theo
Noise and Periodic Modulations in Neural Excitable Media
We have analyzed the interplay between noise and periodic modulations in a
mean field model of a neural excitable medium. To this purpose, we have
considered two types of modulations; namely, variations of the resistance and
oscillations of the threshold. In both cases, stochastic resonance is present,
irrespective of if the system is monostable or bistable.Comment: 13 pages, RevTex, 5 PostScript figure
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