Design, construction, and validation of a 1-mm triple-resonance high-temperature-superconducting probe for NMR

We report a 600-MHz 1-mm triple-resonance high-temperature-superconducting (HTS) probe for nuclear magnetic resonance spectroscopy. The probe has a real sample volume of about 7.5 microl, an active volume of 6.3 microl, and appears to have the highest mass sensitivity at any field strength. The probe is constructed with four sets of HTS coils that are tuned to 1H, 2H, 13C, and 15N, and there is a z-axis gradient. The coils are cooled with a conventional Bruker CryoPlatform to about 20 K, and the sample chamber can be regulated above or below room temperature over a moderate range using a Bruker variable temperature unit. The absolute S/N for 0.1% ethylbenzene is approximately 1/3 that of a conventional 5mm probe with just 1/70 of the sample volume. We demonstrate the utility of this probe for small molecules and proteins with 2D spectra of just 1.7 microg of ibuprofen and 400 microM 15N-labeled ubiquitin.     

Post-Lithium-Ion Battery Era: Recent Advances in Rechargeable Potassium-Ion Batteries

Lithium shortage and the growing demand for electricity storage has encouraged researchers to look for new alternative energy-storage materials. Due to abundant potassium resources, similar redox potential to lithium metal, and low cost, potassium-ion batteries (PIBs), as one of the promising alternatives, have been applied in energy-storage research recently. However, PIBs do not have adequate competition in their electrochemical efficiency because the molar volume of potassium ions is higher than those in lithium and sodium ions. Therefore, for better application and development of PIBs, finding suitable anode and cathode materials is currently the most important task. The latest developments in electrode materials for PIBs have been outlined in depth in this review. It focuses on the structural design and synthetic methods for novel electrode materials, ingenious optimization and tuning strategies, and explains the intrinsic reaction mechanism. The effects of organic electrolytes and aqueous electrolytes on battery systems are compared and clarified. Finally, theoretical and viable insights are given to the challenges posed by the creation and practical application of PIBs in the future.     

Influence of the environment in 40K concentration in Brazilian common beans

The consumption of beans constitutes an important dietary habit in many Latin American, Asian and African countries. Carioca beans and the black type stand out among the many consumed common beans in Brazil. ⁴⁰K was used as a natural radiotracer to evaluate the influence of the season growing and the bean type in the potassium content into grain. The activity concentrations of ⁴⁰K and ¹³⁷Cs were evaluated on samples of beans by γ-ray spectrometry. ¹³⁷Cs was less than 1.3 Bq kg ^?1. The highest potassium content in the grain were observed in the dry and winter seasons. The black beans showed higher potassium content than the carioca type. The potassium levels were compared with that of beans grown and consumed in other regions of the world. A method to estimate the bean consumption rates in Brazil independently of the location of the meal is proposed. The ingestion of common beans was estimated in 14.6 kg year^?1 per person. The two regions with the highest consumption are the Southeast (19.2 kg year^?1) and the Middle West (18.7 kg year^?1), whose account for about 60 % of the intake of common beans is related to consumption out home.     

Opto-electronic properties of blue phosphorene oxide with and without oxygen vacancies

Blue phosphorene is an attractive nanomaterial that exhibits some remarkable optoelectronic properties. Various studies have verified its ability to adsorb gaseous compounds and, in particular, to dissociate O₂, forming covalent bonds between phosphorus and oxygen atoms. These covalent bonds could be the reason behind the oxidation reaction that affects the blue phosphorene in normal room conditions. Theoretically, it has been demonstrated that the blue phosphorene oxide (BPO) is just as stable as the blue phosphorene. Given that metallic oxides are widely used as catalyzers and gas sensors, this opens the possibility of the BPO being presented as a gas sensor as well. For all the above, in this work the optoelectronic properties of BPO were studied, along with the generation of the oxygen vacancies. The investigation was performed within the density functional theory (DFT). In the study of the oxygen vacancy, the formation energy was calculated, and the results are similar to the formation energies of oxygen vacancies in other known oxides. It was found that the BPO with a single vacancy has a favorable energetic stability. The characterization of the vacancy is achieved using the electronic structure and the optical response. Additionally, the analysis of the adsorption of a hydrogen atom on the BPO, and the subsequent formation of hydroxide is presented.     

ChemInform Abstract: B182‐: A Quasi‐Planar Bowl Member of the Wankel Motor Family.

Bowl‐like structured B₁₈^2‐ as the fifth member of the so‐called “Wankel motor” family is found.     

Thin film optimization design of organic–inorganic hybrids for waveguide high‐rejection optical filters

We report the fabrication of transparent, low surface roughness (<0.1 nm), and low‐loss (1.5 ± 0.2 dB cm^–1, 532 nm) thin films of organic–inorganic hybrids with controlled refractive index values stable under aging. High‐rejection optical filters based on first‐order Bragg gratings inscribed in channel waveguides were fabricated using UV‐laser writing. Their high‐rejection figure of merit (～24 dB) is the best value found until now for organic–inorganic hybrids reinforcing the potential of sol–gel technology in the integration of optoelectronic components based on hybrid materials, namely in the fabrication of cost‐effective integrated optics devices. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural evolution of small gold clusters doped by one and two boron atoms

The potential energy surfaces (PES) of a series of gold–boron clusters with formula Au_nB (n = 1–8) and Au_mB₂ (m = 1–7) have been explored using a modified stochastic search algorithm. Despite the complexity of the PES of these clusters, there are well‐defined growth patterns. The bonding of these clusters is analyzed using the adaptive natural density partitioning and the natural bonding orbital analyses. Reactivity is studied in terms of the molecular electrostatic potential. © 2014 Wiley Periodicals, Inc.