Hydrazine is a chemical of utmost importance in our society, either for organic synthesis or energy use. The direct conversion of NH3 to hydrazine is highly appealing, but it remains a very difficult ...task because the degradation of hydrazine is thermodynamically more feasible than the cleavage of the N−H bond of NH3. As a result, any catalyst capable of activating NH3 will thus unavoidably decompose N2H4. Here we show that cavitation bubbles, created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as microreactors to activate and convert NH3 to NH species, without assistance of any catalyst, yielding hydrazine at the bubble–liquid interface. The compartmentation of in‐situ‐produced hydrazine in the bulk solution, which is maintained close to 30 °C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies. This work also points towards a path to scavenge .OH radicals by adjusting the NH3 concentration.
Cavitation bubbles act as microreactors to activate NH3, resulting in the formation of NH species that further recombine to hydrazine at the bubble–liquid interface. One of the advantages of this technology is the compartmentation of the as‐formed hydrazine in the bulk solution, maintained at only 30 °C, which limits its thermal degradation.
Ammoniak kann in Hydrazin umgewandelt werden, eine Chemikalie von größter Bedeutung für die organische Synthese und für Energiezwecke. In ihrer Zuschrift auf S. 25434 berichten François Jérôme et ...al., dass Kavitationsblasen, die durch Ultraschallbestrahlung von wässrigem Ammoniak mit hoher Frequenz erzeugt werden, als Mikroreaktoren fungieren, um Ammoniak zu aktivieren und an der Gas‐Flüssigkeits‐Grenzfläche in Hydrazin umzuwandeln. Die wässrige Lösung, die bei einer Temperatur von 30 °C gehalten wird, verhindert den Abbau des in situ hergestellten Hydrazins.
Functionalized aromatic chemicals have been produced from furfural, a building block available on a large scale from low‐cost biomass. In their Communication on page 10510 ff., R. Wischert, F. Jérôme ...et al. report their strategy that relies on a Diels–Alder/aromatization sequence. By controlling the rate of each step, it was possible to produce exclusively the meta aromatic isomer. meta‐Xylylenediamine was synthesized.
The preparation of dense fibrillar collagen matrices, through a sol/gel transition at variable concentrations, offers routes to produce a range of simple, non toxic materials. Concentrated hydrogels ...entrapping cells show enhanced properties in terms of reduced contraction and enhanced cell proliferation. Dense fibrillar matrices attain tissue like mechanical properties and show ultrastructures described in connective tissues, namely liquid crystalline cholesteric geometries. Their colonization by cells and possible association with a mineral phase in a tissue like manner validate their use as biomimetic materials for regenerative medicine.
El mercado de microcréditos (MC) de Argentina presenta un bajo desarrollo, comparado con sus países vecinos. Esta situación, si bien puede verse como un problema o un obstáculo, también representa ...una oportunidad para crecer. Al indagar sobre las causas de dicho subdesarrollo, se observa que la información acerca de la oferta de MC es escasa e insuficiente para realizar un análisis profundo de dicho mercado. Por ello, el objetivo de este trabajo es aportar evidencia acerca de la estructura de la oferta de MC en Argentina a partir de un análisis descriptivo. El principal aporte de este trabajo es establecer los parámetros esenciales que permitirán sentar las bases para dar respuesta al escaso desarrollo de las microfinanzas en Argentina.
Non-conventional stable isotopes have received increasing attention in the past decade to investigate multi-level ecological connections from individuals to ecosystems. More recently, isotopes from ...trace and non-nutrient elements, potentially toxic (i.e., Hg), have also been recognized of great significance to discriminate sources, transports, and bioaccumulation, as well as trophic transfers. In contrast, lithium (Li) concentrations and its isotope compositions (δ
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Li) remain poorly documented in aquatic ecosystems, despite its possible accumulation in marine organisms, its increasing industrial production, and its demonstrated hazardous effects on biota. Here, we present the first Li isotope investigation of various soft tissues, organs or whole organisms, from marine plankton, bivalves, cephalopods, crustaceans, and fish of different biogeographical regions North Mediterranean Sea, North Atlantic Ocean (Bay of Biscay), South East Pacific Ocean (New Caledonia), and Southern Indian Ocean (Kerguelen Islands). Independently of the considered organisms, δ
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Li values range widely, from 4.6‰ (digestive gland of bivalves) to 32.0‰ (zooplankton). Compared to homogeneous seawater (δ
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Li ∼ 31.2‰ ± .3‰), marine organisms mostly fractionate Li isotopes in favor of the light isotope (
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Li). Within the same taxonomic group, significant differences are observed among organs, indicating a key role of physiology on Li concentrations and on the distribution of Li isotopes. Statistically, the trophic position is only slightly related to the average Li isotope composition of soft tissues of marine organisms, but this aspect deserves further investigation at the organ level. Other potential influences are the Li uptake by ingestion or gill ventilation. Overall, this work constitutes the first δ
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Li extensive baseline in soft tissues of coastal organisms from different large geographic areas mostly preserved from significant anthropogenic Li contamination.
The dentate granule cells (DGCs) play a crucial role in learning and memory. Many studies have described the role and physiological properties of these sparsely active neurons using different ...behavioral contexts. However, the morpho-functional features of DGCs recruited in mice maintained in their home cage (without training), considered as a baseline condition, have not yet been established. Using fosGFP transgenic mice, we observed
that DGCs recruited in animals maintained in the home cage condition are mature neurons that display a longer dendritic tree and lower excitability compared with non-activated cells. The higher GABA
receptor-mediated shunting inhibition contributes to the lower excitability of DGCs activated in the home environment by shifting the input resistance towards lower values. Remarkably, that shunting inhibition is neither observed in non-activated DGCs nor in DGCs activated during training in virtual reality. In short, our results suggest that strong shunting inhibition and reduced excitability could constitute a distinctive neural signature of mature DGCs recruited in the context of the home environment.
OBJECTIVES:Premature babies require supplementation with calcium (Ca) and phosphorus (P) to prevent metabolic bone disease of prematurity. To guide mineral supplementation, 2 methods of monitoring ...urinary excretion of Ca and P are usedurinary Ca or P concentration and Ca/creatinine (Crea) or P/Crea ratios. We compare these 2 methods in regards to their agreement on the need for mineral supplementation.
METHODS:Retrospective chart review of 230 premature babies with birth weight <1500 g, undergoing screening of urinary spot samples from day 21 of life and fortnightly thereafter. Hypothetical cutoff values for urine Ca or P concentration (1 mmol/L) and urine Ca/Crea ratio (0.5 mol/mol) or P/Crea ratio (4 mol/mol) were applied to the sample results. The agreement on whether to supplement the respective minerals based on the results with the 2 methods was compared. Multivariate general linear models sought to identify patient characteristics to predict discordant results.
RESULTS:A total of 24.8% of cases did not agree on the indication for Ca supplementation, and 8.8% for P. Total daily Ca intake was the only patient characteristic associated with discordant results.
CONCLUSIONS:With the intention to supplement the respective mineral, comparison of urinary mineral concentration with mineral/Crea ratio is moderate for Ca and good for P. The results do not allow identifying superiority of either method on the decision as to which babies require Ca and/or P supplements.
We present a spectroscopic study aimed at a better understanding of solid-amine CO2 sorbent materials that employ amine moieties in mesoporous hosts (here, mesoporous silica SBA15). The materials are ...exposed to water (or D2O) and isotopically enriched 13CO2 to examine the chemisorption products found with these compositions under conditions relevant to carbon capture from combustion sources. Bicarbonate species have been only recently characterized by solid-state NMR as a product found under humid carbon capture conditions using tertiary amines. Here, we extend these findings to characterize multiple bicarbonate environments (using low-temperature solid-state NMR) associated with not only tertiary but also secondary and primary amine sites using two-dimensional 13C–1H heteronuclear correlation (HETCOR) NMR. The use of D2O provides enhanced resolution in the HETCOR spectra by diluting the protons present and reducing the homonuclear dipolar coupling. One bicarbonate environment is coupled to water present on the walls of the mesoporous silica support, whereas the other bicarbonate is coordinated to water and located in the pore or “mid-channel” while still being coupled to the pendant amine moieties. The identification of bicarbonate in primary and secondary amines, the detection of which was previously obscured by dynamic motion attenuating detection via cross-polarization magic-angle spinning NMR, is presented as well. These findings will help further quantify the presence of both carbamate and bicarbonate in carbon capture materials in the future.
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