Monitoring Galvanic Replacement Through Three-Dimensional Morphological and Chemical Mapping

Galvanic replacement reactions on metal nanoparticles are often used for the preparation of hollow nanostructures with tunable porosity and chemical composition, leading to tailored optical and catalytic properties. However, the precise interplay between the three-dimensional (3D) morphology and chemical composition of nanostructures during Galvanic replacement is not always well understood as the 3D chemical imaging of nanoscale materials is still challenging. It is especially far from straightforward to obtain detailed information from the inside of hollow nanostructures using electron microscopy techniques such as SEM or TEM. We demonstrate here that a combination of state-of-the-art EDX mapping with electron tomography results in the unambiguous determination of both morphology transformation and elemental composition of nanostructures in 3D, during Galvanic replacement of Ag nanocubes. This work provides direct and unambiguous experimental evidence leading to new insights in the understanding of the galvanic replacement reaction. In addition, the powerful approach presented here can be applied to a wide range of nanoscale transformation processes, which will undoubtedly guide the development of novel nanostructures

Can Dispersed Biomass Processing Protect the Environment and Cover the Bottom Line for Biofuel?

This paper compares environmental and profitability outcomes for a centralized biorefinery for cellulosic ethanol that does all processing versus a biorefinery linked to a decentralized array of local depots that pretreat biomass into concentrated briquettes. The analysis uses a spatial bioeconomic model that maximizes predicted profit from crop and energy products, subject to the requirement that the biorefinery must be operated at full capacity. The model draws upon biophysical crop input-output coefficients simulated with the EPIC model, as well as input and output prices, spatial transportation costs, ethanol yields from biomass, and biorefinery capital and operational costs. The model was applied to 82 cropping systems simulated across 37 sub-watersheds in a 9-county region of southern Michigan in response to ethanol prices simulated to rise from $1.78 to$3.36 per gallon. Results show that the decentralized local biomass processing depots lead to lower profitability but better environmental performance, due to more reliance on perennial grasses than the centralized biorefinery. Simulated technological improvement that reduces the processing cost and increases the ethanol yield of switchgrass by 17% could cause a shift to more processing of switchgrass, with increased profitability and environmental benefits.Biomass production, bioenergy supply, cellulosic ethanol, environmental trade-off analysis, bioeconomic modeling, EPIC, spatial configuration, local biomass processing, Crop Production/Industries, Environmental Economics and Policy, Production Economics, Resource /Energy Economics and Policy, Q16, Q15, Q57, Q18,

On the relationship between proteinuria and plasma phosphate.

Albuminuria is strongly associated with renal and cardiovascular outcomes independently of renal function level. However, the pathophysiology of these associations is debated. In chronic kidney disease (CKD), phosphate retention participates in cardiovascular events and increased cardiovascular mortality. We hypothesised that albuminuria may modulate tubular phosphate handling by the kidney. To verify this hypothesis, we first studied the association between phosphataemia and albuminuria in children with nephrotic syndrome and in adults with CKD. In both cases, higher albuminuria was associated with higher phosphate level, independently of glomerular filtration rate. We further tried to decipher the molecular mechanisms of these observations. Using animal models of nephrotic proteinuria, we could show that albuminuric rats and mice had abnormally elevated sodium-phosphate apical co-transporter expression, despite elevated fibroblast growth factor 23 (FGF23). The FGF23 downstream pathway was inhibited despite elevated FGF23 levels. Klotho protein expression was also lower in proteinuric animals compared to controls. Finally, albumin had no direct effects on phosphate transport in cells. Altogether, we show that albuminuria induces alteration of phosphate tubular handling, independently of glomerular filtration rate. The mechanisms involved appear to include Klotho down-regulation and resistance to FGF23. This observation may link albuminuria to increased cardiovascular disease via altered phosphate handling. Finally, this observation opens up further opportunities to better understand the link between albuminuria, Klotho, FGF23 and phosphate handling

Atomic Layer Deposition-Based Synthesis of Photoactive TiO2 Nanoparticle Chains by Using Carbon Nanotubes as Sacrificial Templates

Highly ordered and self supported anatase TiO2 nanoparticle chains were fabricated by calcining conformally TiO2 coated multi-walled carbon nanotubes (MWCNTs). During annealing, the thin tubular TiO2 coating that was deposited onto the MWCNTs by atomic layer deposition (ALD) was transformed into chains of TiO2 nanoparticles (~12 nm diameter) with an ultrahigh surface area (137 cm2 per cm2 of substrate), while at the same time the carbon from the MWCNTs was removed. Photocatalytic tests on the degradation of acetaldehyde proved that these forests of TiO2 nanoparticle chains are highly photo active under UV light because of their well crystallized anatase phase

Synthesis of a 3D network of Pt nanowires by atomic layer deposition on carbonaceous template

The formation of a 3D network composed of free standing and interconnected Pt nanowires is achieved by a two-step method, consisting of conformal deposition of Pt by atomic layer deposition (ALD) on a forest of carbon nanotubes and subsequent removal of the carbonaceous template. Detailed characterization of this novel 3D nanostructure was carried out by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). These characterizations showed that this pure 3D nanostructure of platinum is self-supported and offers an enhancement of the electrochemically active surface area by a factor of 50

Electronically coupled complementary interfaces between perovskite band insulators

Perovskite oxides exhibit a plethora of exceptional electronic properties, providing the basis for novel concepts of oxide-electronic devices. The interest in these materials is even extended by the remarkable characteristics of their interfaces. Studies on single epitaxial connections between the two wide-bandgap insulators LaAlO3 and SrTiO3 have revealed them to be either high-mobility electron conductors or insulating, depending on the atomic stacking sequences. In the latter case they are conceivably positively charged. For device applications, as well as for basic understanding of the interface conduction mechanism, it is important to investigate the electronic coupling of closely-spaced complementary interfaces. Here we report the successful realization of such electronically coupled complementary interfaces in SrTiO3 - LaAlO3 thin film multilayer structures, in which the atomic stacking sequence at the interfaces was confirmed by quantitative transmission electron microscopy. We found a critical separation distance of 6 perovskite unit cell layers, corresponding to approximately 2.3 nm, below which a decrease of the interface conductivity and carrier density occurs. Interestingly, the high carrier mobilities characterizing the separate electron doped interfaces are found to be maintained in coupled structures down to sub-nanometer interface spacing

Blood glucose, diabetes and metabolic control in patients with community-acquired pneumonia

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Задачи глобальной экологии

Changes in the size distribution and composition of bimetallic Pd-Au nanoclusters have been observed after hydrogen exposure. This effect is caused by hydrogen-induced Ostwald ripening whereby the hydrogen reduces the binding energy of the cluster atoms leading to their detachment from the cluster. The composition changes due to a difference in mobility of the detached palladium and gold atoms on the surface. Fast palladium atoms contribute to the formation of larger nanoclusters, while the slower gold atoms are confined to the smaller nanoclusters. These transformations in the Pd-Au nanocluster size and composition set a limit for chemical reactions in which such nanoclusters are involved together with hydrogen