Rearrangement under control: A wide variety of 3,4,5‐ and 1,3,5‐trisubstituted pyrazoles can be prepared from tosylhydrazones of ketones and terminal alkynes through the title reaction sequence (see ...scheme; Ts=4‐toluenesulfonyl). The rearrangement, and therefore, the regioselectivity of the reaction is controlled by the nature of the substituents of the tosylhydrazone.
The reactions between terminal alkynes and α‐chiral tosylhydrazones lead to the obtention of chiral pyrazoles with a stereogenic group directly attached at a nitrogen atom. The cascade reaction ...includes decomposition of the hydrazone into a diazocompound, 1,3‐dipolar cycloaddition of the diazo compound with the alkyne, and 1,5 sigmatropic rearrangement with migration of the stereogenic group. This strategy has been successfully applied to the synthesis of structurally diverse chiral pyrazoles through α‐chiral tosylhydrazones, obtained from α‐phenylpropionic acid, α‐amino acids, and 2‐methoxycyclohexanone. Notably, the stereoretention of the 1,5 sigmatropic rearrangements represent very rare examples of this stereospecific transformation.
Maintaining a (con)figur(ation): Retention of configuration in 1,5 sigmatropic shifts are predicted by the Woodward–Hoffmann rules, but are not well‐documented experimentally. Such shifts are observed in the reactions of α‐chiral tosylhydrazones with terminal alkynes. The chiral pyrazole products are formed by a 1,3‐dipolar cycloaddition and subsequent site‐, regio‐, and stereospecific 1s,5s sigmatropic rearrangement. Ts=4‐toluenesulfonyl.
The partners decide: The CC bond‐forming reductive cross‐coupling of alkenylboronic acids and tosylhydrazones takes place under mild reaction conditions without the need of a metal catalyst, thus ...giving rise to olefination‐type products (see scheme). The position of the double bond in the product is determined by the structure of the coupling partners.
Growth factors play a crucial role in tissue engineering by directing the fate of cells and allowing the formation of tissues. Understanding the key requirements for growth factor delivery can point ...the way towards novel tissue engineering platforms. Growth factor suffer from a tendency to lose their bioactivity upon environmental and physical changes. The need for biomaterials that can preserve the native form of growth factor has directed interest towards hydrogels (e.g. gelatin, alginate) and hydrophobic polymers (e.g. polycaprolactone). In recent advances, the use of composite materials such as PCL-chitosan (hydrogel-hydrophobic polymer) and gelatin-alginate (hydrogel-hydrogel polymers) has opened the possibility of fine tuning the delivery systems. Other current research is exploring new delivery strategies for growth factors such as the use of bioreactors and delivery by molecule-recognition. In particular, systems that allow the delivery of growth factors in a 3-dimensional manner are promising compared to conventional methods. This review analyses the biological considerations, material selection, and delivery strategies that have been established as the pivotal components for growth factor delivery and will support the next generation of tissue engineering platforms by providing a comprehensive landscape for the growth factor delivery field. The last part of the review discusses the current challenges and promising future directions for delivering growth factors.
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•The relationship between biologicals-materials-delivery strategy .•Biological considerations for the preservation of bioactivity/functionality.•The influence of the affinity between a material and growth factor on the release.•Traditional and novel strategies to deliver growth factors.•Challenges towards clinically-translatable delivery of growth factors.
The latest breed of very high resolution (VHR) commercial satellites opens new possibilities for cartographic and remote-sensing applications. In fact, one of the most common applications of ...remote-sensing images is the extraction of land-cover information for digital image base maps by means of classification techniques. The aim of the study was to compare the potential classification accuracy provided by pan-sharpened orthoimages from both GeoEye-1 and WorldView-2 (WV2) VHR satellites over urban environments. The influence on the supervised classification accuracy was evaluated by means of an object-based statistical analysis regarding three main factors: (i) sensor used; (ii) sets of image object (IO) features used for classification considering spectral, geometry, texture, and elevation features; and (iii) size of training samples to feed the classifier (nearest neighbour (NN)). The new spectral bands of WV2 (Coastal, Yellow, Red Edge, and Near Infrared-2) did not improve the benchmark established from GeoEye-1. The best overall accuracy for GeoEye-1 (close to 89%) was attained by using together spectral and elevation features, whereas the highest overall accuracy for WV2 (83%) was achieved by adding textural features to the previous ones. In the case of buildings classification, the normalized digital surface model computed from light detection and ranging data was the most valuable feature, achieving producer's and user's accuracies close to 95% and 91% for GeoEye-1 and VW2, respectively. Last but not least and regarding the size of the training samples, the rule of ‘the larger the better' was true but, based on statistical analysis, the ideal choice would be variable depending on both each satellite and target class. In short, 20 training IOs per class would be enough if the NN classifier was applied on pan-sharpened orthoimages from both GeoEye-1 and WV2.
The presence of heavy metals in the sludges produced in wastewater treatment plants restricts their use for agricultural purposes. This study looks at different types of sludge (aerobic, anaerobic, ...unstabilised, sludge from a waste stabilisation pond, sludge from an extended aeration plant and heat treated sludge) and compares the distribution of heavy metals with the treatment that they have undergone. In addition, the total quantity of metals (Cd, Cr, Cu, Ca, K, Fe, Mg, Ni, Na, Pb and Zn) and some agronomic parameters necessary for characterising a sludge as suitable for use as amendment were determined. The BCR method for heavy metal speciation was followed. Principal component analysis (PCA) was applied in order to obtain more information about metal speciation in the sewage sludges. It was confirmed that the concentration of heavy metals did not exceed the limits set out by European legislation and that the stabilisation treatment undergone by the sludges strongly influenced the heavy metal distribution and the phases to which they were associated. The waste stabilisation pond sludge, which has undergone a higher degree of mineralisation than the others, shows a lower metal bioavailability index since practically all the heavy metals in it are associated to the oxidisable and residual fraction. On the other hand the unstabilised sludge, which, along with that exposed to extended aeration, contains the highest accumulations of heavy metals in the most easily assimilable fractions.
In 1927, at the Solvay conference, Einstein posed a thought experiment with the primary intention of showing the incompleteness of quantum mechanics; to prove it, he employed the instantaneous ...nonlocal effects caused by the collapse of the wavefunction of a single particle-the spooky action at a distance-, when a measurement is done. This historical event preceded the well-know Einstein-Podolsk-Rosen criticism over the incompleteness of quantum mechanics. Here, by using the Stern-Gerlach experiment, we demonstrate how the instantaneous nonlocal feature of the collapse of the wavefunction together with the single-particle entanglement can be used to produce the nonlocal effect of steering, i.e. the single-particle steering. In the steering process Bob gets a quantum state depending on which observable Alice decides to measure. To accomplish this, we fully exploit the spreading (over large distances) of the entangled wavefunction of the single-particle. In particular, we demonstrate that the nonlocality of the single-particle entangled state allows the particle to "know" about the kind of detector Alice is using to steer Bob's state. Therefore, notwithstanding strong counterarguments, we prove that the single-particle entanglement gives rise to truly nonlocal effects at two faraway places. This opens the possibility of using the single-particle entanglement for implementing truly nonlocal task.
•Leafy Amaranthus spp. are excellent sources of magnesium and vitamin C.•Leafy Amaranthus spp. have higher mineral levels than many common leafy vegetables.•Amaranthus blitum and A. tricolor have the ...highest vitamin C concentrations.•A one cup serving of Amaranthus acanthochiton is a good source of Ca, Mn, and Mo.•Amaranthus cruentus has the highest level of antioxidant activity.
The objective of this study was to evaluate mineral, vitamin C, phenolic and flavonoid concentrations and antioxidant activity levels in 15 leafy Amaranthus species. Across species, the concentration ranges of Ca, K, Mg, P and phenolics, and activity ranges of antioxidants in amaranth leaves were 1.5–3.5mg/g, 5.5-8.8mg/g, 1.8–4.5mg/g, 0.5–0.9mg/g, 3.2–5.5mg gallic acid equivalents/g, and 38–90μmol Trolox equivalents/g (all values on a fresh weight FW basis), respectively. Amaranthus acanthochiton had the highest concentrations of Ca, Mg, Ni, Zn, and A. deflexus and A. viridis had the highest concentrations of Fe. A serving of any of the Amaranthus leaves (1 cup; 30g FW) would contribute from 13 to 34% of the daily value (DV) of Mg (DV=400mg; as established by the US Food and Drug Administration), and up to 68% of the DV of vitamin C (DV=60mg). In addition, A. acanthochiton would be considered a good source of Ca, Mn and Mo (10%–19% of the DV), and an excellent source of Mg and vitamin C (20% or more of the DV). Amaranth leafy vegetables should be promoted as a dietary source of essential nutrients and health-beneficial compounds.
The modulation of nanoparticles' size, shape, and dispersion by polymers has attracted particular attention in different fields. Nevertheless, there is a lack of information regarding the use of ...charged macromolecules as assistants in the nanostructures' nucleation and growth processes. Prompted by this, the in situ synthesis of gold nanoparticles (AuNPs) aided by hydrolyzed polyacrylamides (HPAM), with different chemical structures, was developed. In contrast to the conventional synthesis of nanostructures assisted by polyacrylamide, here, the polymerization, hydrolysis, and nanostructure formation processes were carried out simultaneously in the same milieu. Likewise, the growing chains acted as a template for the nanoparticles' growth, so their conformations and chemical structure, especially the amount of charges along the chain, played an important role in the AuNPs' morphology, size, and some of the final composite features. The nanocomposite was thoroughly characterized with appropriate techniques, including ATR-FTIR, GPC, UV-Vis, and SEM.
Based on a digital ethnography on the imageboard platform 4chan/pol, this article traces the biopolitical compression of Population Replacement Conspiracy Theories into memes, which have populated ...far-right boards in the last decade. The article makes an argument for the relevance of studying the relation between the intellectual elaboration of Conspiracy Theories and their compression into concise and easily consumable memes, by fleshing out the functionality of memes in the argumentative economy of Conspiracy theories, (a) as encoding and compressing their core components; (b) by filling in the (unspoken) gaps in the logic of Conspiracy theories; and (c) by advancing a biopolitical understanding of social life.
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