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Diesel engine vehicles, despite their good fuel economy and reduced CO2, are receiving significant attention and negative publicity in recent years due to their difficulties in ...achieving the emissions regulations. This has widely been linked to undesirable environmental impact and health effects.
The lower exhaust gas temperatures associated with modern and more efficient hybrid powertrain and diesel engines makes current technology catalytic aftertreatment systems less efficient under range of vehicle operating conditions. This study, demonstrates how changes in the commonly used aftertreatment system architecture and changes in fuel composition in this case through the addition of oxygenated fuels (i.e. butanol) in diesel fuel can provide meaningful low temperature catalyst activity improvements.
The catalyst oxidation kinetics of CO and HC species were improved (reduced the light-off temperature by around 20 °C) when a diesel particulate filter (DPF) was placed upstream of the DOC, while the combination of DPF and combustion of oxygenated fuel in diesel led to up to 80 °C improvement in catalyst activity. The prevention of soot reaching the DOC active sites increases the rate of reactions and the species accessibility to the active sites of the catalyst, and thereby the oxidation of emissions (CO, HC, and NO) can occur at lower catalyst temperatures. The combustion of diesel-butanol blend further improved the DOC low temperature activity. The major contributors to the improved catalyst light-off, are the reduced level of soot and hydrocarbon emissions as well as the higher reactivity of the hydrocarbons species emitted under butanol blend combustion.
The peer-reviewed marine pharmacology literature from 2009 to 2011 is presented in this review, following the format used in the 1998-2008 reviews of this series. The pharmacology of ...structurally-characterized compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral pharmacological activities were reported for 102 marine natural products. Additionally, 60 marine compounds were observed to affect the immune and nervous system as well as possess antidiabetic and anti-inflammatory effects. Finally, 68 marine metabolites were shown to interact with a variety of receptors and molecular targets, and thus will probably contribute to multiple pharmacological classes upon further mechanism of action studies. Marine pharmacology during 2009-2011 remained a global enterprise, with researchers from 35 countries, and the United States, contributing to the preclinical pharmacology of 262 marine compounds which are part of the preclinical pharmaceutical pipeline. Continued pharmacological research with marine natural products will contribute to enhance the marine pharmaceutical clinical pipeline, which in 2013 consisted of 17 marine natural products, analogs or derivatives targeting a limited number of disease categories.
MasterChem: cooking 2D-polymers Rodríguez-San-Miguel, D; Amo-Ochoa, P; Zamora, F
Chemical communications,
01/2016, Letnik:
52, Številka:
22
Journal Article
Recenzirano
Odprti dostop
2D-polymers are still dominated by graphene and closely related materials such as boron nitride, transition metal sulphides and oxides. However, the rational combination of molecules with suitable ...design is already showing the high potential of chemistry in this new research field. The aim of this feature article is to illustrate, and provide some perspectives, the current state-of-the-art in the field of synthetic 2D-polymers showing different alternatives to prepare this novel type of polymers based on the rational use of chemistry. This review comprises a brief revision of the essential concepts, the strategies of preparation following the two general approaches, bottom-up and top-down, and a revision of the promising seminal properties showed by some of these nanomaterials.
This review summarized the current state-of-the-art in the field of synthetic 2D-polymers showing different routes to prepare these polymers and their physical properties.
Pollution of coasts by toxic metals and metalloids is a worldwide problem for which phytoremediation using halophytes and associated microbiomes is becoming relevant. Metal(loid) excess is a ...constraint for plant establishment and development, and plant growth promoting rhizobacteria (PGPR) mitigate plant stress under these conditions. However, mechanisms underlying this effect remain elusive. The effect of toxic metal(loid)s on activity and gene expression of ROS-scavenging enzymes in roots of the halophyte Spartina densiflora grown on real polluted sediments in a greenhouse experiment was investigated. Sediments of the metal-polluted joint estuary of Tinto and Odiel rivers and control, unpollutred samples from the Piedras estuary were collected and submitted to ICP-OES. Seeds of S. densiflora were collected from the polluted Odiel marshes and grown in polluted and unpolluted sediments. Rhizophere biofilm-forming bacteria were selected based on metal tolerance and inoculated to S. densiflora and grown for 4 months. Fresh or frozen harvested plants were used for enzyme assays and gene expression studies, respectively. Metal excess induced SOD (five-fold increase), whereas CAT and ascorbate peroxidase displayed minor induction (twofold). A twofold increase of TBARs indicated membrane damage. Our results showed that metal-resistant PGPR (P. agglomerans RSO6 and RSO7 and B. aryabhattai RSO25) contributed to alleviate metal stress, as deduced from lower levels of all antioxidant enzymes to levels below those of non-exposed plants. The oxidative stress index (OSI) decreased between 50 and 75% upon inoculation. The results also evidenced the important role of PAL, involved in secondary metabolism and/or lignin synthesis, as a pathway for metal stress management in this halophyte upon inoculation with appropriate PGPR, since the different inoculation treatments enhanced PAL expression between 3.75- and five-fold. Our data confirm, at the molecular level, the role of PGPR in alleviating metal stress in S. densiflora and evidence the difficulty of working with halophytes for which little genetic information is available.
We compared the effects of two resistance training (RT) programs only differing in the repetition velocity loss allowed in each set: 20% (VL20) vs 40% (VL40) on muscle structural and functional ...adaptations. Twenty‐two young males were randomly assigned to a VL20 (n = 12) or VL40 (n = 10) group. Subjects followed an 8‐week velocity‐based RT program using the squat exercise while monitoring repetition velocity. Pre‐ and post‐training assessments included: magnetic resonance imaging, vastus lateralis biopsies for muscle cross‐sectional area (CSA) and fiber type analyses, one‐repetition maximum strength and full load‐velocity squat profile, countermovement jump (CMJ), and 20‐m sprint running. VL20 resulted in similar squat strength gains than VL40 and greater improvements in CMJ (9.5% vs 3.5%, P < 0.05), despite VL20 performing 40% fewer repetitions. Although both groups increased mean fiber CSA and whole quadriceps muscle volume, VL40 training elicited a greater hypertrophy of vastus lateralis and intermedius than VL20. Training resulted in a reduction of myosin heavy chain IIX percentage in VL40, whereas it was preserved in VL20. In conclusion, the progressive accumulation of muscle fatigue as indicated by a more pronounced repetition velocity loss appears as an important variable in the configuration of the resistance exercise stimulus as it influences functional and structural neuromuscular adaptations.
In-tube solid-phase microextraction (in-tube SPME or IT-SPME) is a sample preparation technique which has demonstrated over time its ability to couple with liquid chromatography (LC), as well as its ...advantages as a miniaturized technique. However, the in-tube SPME perspectives in the forthcoming years depend on solutions that can be brought to the environmental, industrial, food and biomedical analysis. The purpose of this scoping review is to examine the strengths and weaknesses of this technique during the period 2009 to 2015 in order to identify research gaps that should be addressed in the future, as well as the tendencies that are meant to strengthen the technique.
In terms of methodological aspects, this scoping review shows the in-tube SPME strengths in the coupling with LC (LC-mass spectrometry, capillary LC, ultra-high-pressure LC), in the new performances (magnetic IT-SPME and electrochemically controlled in-tube SPME) and in the wide range of development of coatings and capillaries. Concerning the applicability, most in-tube SPME studies (around 80%) carry out environmental and biomedical analyses, a lower number food analyses and few industrial analyses. Some promising studies in proteomics have been performed. The review makes a critical description of parameters used in the optimization of in-tube SPME methods, highlighting the importance of some of them (i.e. type of capillary coatings). Commercial capillaries in environmental analysis and laboratory-prepared capillaries in biomedical analysis have been employed with good results. The most consolidated configuration is in-valve mode, however the cycle mode configuration is frequently chosen for biomedical analysis. This scoping review revealed that some aspects such as the combination of in-tube SPME with other sample treatment techniques for the analysis of solid samples should be developed in depth in the near future.
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•A scoping review was carried out, which assesses the strengths and weaknesses of IT-SPME during the period 2009–2015.•Optimization parameters are discussed, with special emphasis on the most decisive ones.•New couplings, performances and capillaries as strength elements.•Benefits and drawbacks of the extraction modes and configurations.•IT-SPME applicability to different matrices and analytes.
Abstract
We present Atacama Large Millimeter/sub-millimeter Array Cycle-2 observations of the HBC 494 molecular outflow and envelope. HBC 494 is an FU Ori-like object embedded in the Orion A cloud ...and is associated with the reflection nebulae Re50 and Re50N. We use 12CO, 13CO and C18O spectral line data to independently describe the outflow and envelope structures associated with HBC 494. The moment-1 map of the 12CO emission shows the widest outflow cavities in a Class I object known to date (opening angle ∼150°). The morphology of the wide outflow is likely to be due to the interaction between winds originating in the inner disc and the surrounding envelope. The low-velocity blueshifted and redshifted 13CO and C18O emission trace the rotation and infall motion of the circumstellar envelope. Using molecular line data and adopting standard methods for correcting optical depth effects, we estimate its kinematic properties, including an outflow mass of the order of 10−1 M⊙. Considering the large estimated outflow mass for HBC 494, our results support recent theoretical work suggesting that wind-driven processes might dominate the evolution of protoplanetary discs via energetic outflows.
Using Non-Redundant Mask interferometry (NRM), we searched for binary companions to objects previously classified as transitional discs (TD). These objects are thought to be an evolutionary stage ...between an optically thick disc and optically thin disc. We investigate the presence of a stellar companion as a possible mechanism of material depletion in the inner region of these discs, which would rule out an ongoing planetary formation process in distances comparable to the binary separation. For our detection limits, we implement a new method of completeness correction using a combination of randomly sampled binary orbits and Bayesian inference. The selected sample of 24 TDs belongs to the nearby and young star-forming regions: Ophiuchus (~130 pc), Taurus-Auriga (~140 pc) and IC348 (~220 pc). These regions are suitable to resolve faint stellar companions with moderate to high confidence levels at distances as low as 2 au from the central star. With a total of 31 objects, including 11 known TDs and circumbinary discs from the literature, we have found that a fraction of 0.38 plus or minus 0.09 of the SEDs of these objects are likely due to the tidal interaction between a close binary and its disc, while the remaining SEDs are likely the result of other internal processes such as photoevaporation, grain growth, planet-disc interactions. In addition, we detected four companions orbiting outside the area of the truncation radii and propose that the IR excesses of these systems are due to a disc orbiting a secondary companion.
Two novel dissymmetric diterpenoids, biselisabethoxanes A and B (
and
), were isolated from the hexane extracts of the gorgonian coral
. Biselisabethoxane A (
) represents the first example of a ...marine-derived C
dimer made of two distinct diterpene fragments, whereas biselisabethoxane B (
) is a fused heterodimer stemming from coupling of two amphilectane-based fragments. The structures of
and
were elucidated based on 1D and 2D NMR spectral data analysis. The molecular structure of
was subsequently confirmed by X-ray crystallographic analysis. When evaluated for their inhibitory effects in a series of well-established biological activity assays the isolated compounds were shown to moderately inhibit the growth of
.
High-resolution observations of edge-on protoplanetary disks in emission from molecular species that sample different critical densities and formation pathways offer the opportunity to trace the ...vertical chemical and physical structures of protoplanetary disks. Among the problems that can be addressed is the origin and significance of the bright CN emission that is a ubiquitous feature of disks. Based on analysis of subarcsecond-resolution Atacama Large Millimeter Array archival data for the edge-on Flying Saucer disk (2MASS J16281370-2431391), we establish the vertical and radial differentiation of the CN emitting regions of the disk with respect to those of
12
CO and CS, and we model the physical disk conditions from which the CN emission arises. We demonstrate that the
12
CO (2–1), CN (2–1), and CS
J
= 5–4 emitting regions of the disk decrease in scale height above the midplane, such that
12
CO, CN, and CS trace layers of increasing density and decreasing temperature. We find that at radii >100 au from the central star, CN emission predominantly arises from intermediate layers, while in the inner region of the disk CN appears to arise from layers closer to the midplane. We investigate the physical conditions of the disk within the CN emitting regions, as well as the ranges of CN excitation temperature and column density, via RADEX non-local thermodynamic equilibrium (non-LTE) modeling of the three brightest CN hyperfine lines. Near the disk midplane, where we derive densities of
n
H
2
~ 10
7
cm
−3
at relatively low
T
kin
(~12 K), we find that CN is thermalized, while sub-thermal, non-LTE conditions appear to obtain CN emission from higher (intermediate) disk layers. We consider whether and how the particular spatial location and excitation conditions of CN emission from the Flying Saucer can be related to CN production that is governed, radially and vertically, by the degree of irradiation of the flared disk by X-rays and UV photons from the central star.
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