I-substituted imidazolemanganese(II) complexes

Summary A series of manganese(II) spin-free complexes of the type: MnL_n Cl₂ [L =N-Methylimidazole (MeIm), n = 1,2,3,6; L =_N-ethylimidazole (EtIm), n = 4], MnL_nBr₂ (L = MeIm, n = 2, 4, 6; L = EtIm, n = 4, 6), MnL_nI₂ (L = MeIm, n = 4, 6; L = EtIm, n = 6), MnL_n(NCS)₂ (L = MeIm, n = 3, 4; L = EtIm, n = 4), MnL₆X₂ (L = MeIm, EtIm; X = NO₃, ClO₄, BF₄); (Me₄N)(MnLCl₃)(L = MeIm, EtIm); (Et₄N)[Mn(MeIm)Br₃] and Mn(MeIm)₂(N₃)₂ · 5 H₂O were prepared and characterized. The complexes have either octahedral, distorted octahedral, polymeric octahedral or tetrahedral structures.     

Colossal Stability of SiB11(BO)12−: An Implication as Potential Electrolyte in High-Voltage Alkali-ion Battery

High-voltage alkali metal-ion batteries (AMIBs) require a non-hazardous, low-cost, and highly stable electrolyte with a large operating potential and rapid ion conductivity. Here, we have reported a halogen-free high-voltage electrolyte based on SiB₁₁(BO)₁₂⁻. Because of the weak π-orbital interaction of −BO as well as the mixed covalent and ionic interaction between SiB₁₁-cage and −BO ligand, SiB₁₁(BO)₁₂⁻ has colossal stability. SiB₁₁(BO)₁₂⁻ possesses extremely high vertical detachment energy (9.95 eV), anodic voltage limit (∼10.05 V), and electrochemical stability window (∼9.95 V). Furthermore, SiB₁₁(BO)₁₂⁻ is thermodynamically stable at high temperatures, and its large size allows for faster cation movement. The alkali salts MSiB₁₁(BO)₁₂ (M=Li, Na, and K) are easily dissociated into ionic components. Electrolytes based on SiB₁₁(BO)₁₂⁻ greatly outperform commercial electrolytes. In short, SiB₁₁(BO)₁₂⁻-based compound is demonstrated to be a high-voltage electrolyte for AMIBs.     

UV light-assisted mineralisation and biodetoxification of Ponceau S with hydroxyl and sulfate radicals

The present study reports simultaneous mineralisation and biodetoxification of Ponceau S (3-hydroxy-4-(2-sulfo-4-[4-sulfophenylazo]phenylazo)-2,7-naphthalenedisulfonic acid sodium salt), an azo dye, by UV light assisted oxidation with hydroxyl and sulfate radicals. Metal ion catalysts used in the work were: Fe²⁺ and Ag⁺, and the oxidants used were: hydrogen peroxide and S₂O₈^2?. Strategies adopted to make the processes environmentally benign and economically viable by achieving maximum mineralisation in the shortest possible time are described. Mineralisation efficiency (Em) of various systems was found to follow the order: E_m(Fe²⁺/H₂O₂/UV) > E_m(Fe²⁺/S₂O₈^2?/UV) > E_m(Ag⁺/H₂O₂/UV) ≈ E_m(Ag⁺/S₂O₈^2?/UV). Thus, Fe²⁺ and HP are the most suitable metal ion catalyst and oxidant respectively, showing higher efficiency at pH 3 followed by that at pH 6.6. It is possible to enhance the Fe²⁺/H₂O₂/UV process electrical energy efficiency by maintaining the concentration of Fe at either 0.05 mM or 0.03 mM and that of the oxidant at 2.5 mM. The bioassay study revealed that the Fe²⁺/S₂O₈^2?/UV process biodetoxification efficiency is higher at pH 3 (93.7 %) followed by that at pH 6.6 (80.1 %) at the concentration of Fe ²⁺ and S₂O₈^2? of 0.03 mM and 2.5 mM, respectively. Thus, not only the concentration of Fe²⁺, but also the nature of the oxidant and pH play an important role in the biodetoxification process and S₂O₈^2? possesses higher biodetoxification efficiency than H₂O₂.     

Multiplexing fibre optic near infrared (NIR) spectroscopy as an emerging technology to monitor industrial bioprocesses

The application of near infrared spectroscopy in bioprocessing has been limited by its dependence on calibrations derived from single bioreactor at a given time. Here, we propose a multiplexed calibration technique which allows calibrations to be built from multiple bioreactors run in parallel. This gives the flexibility to monitor multiple vessels and facilitates calibration model transfer between bioreactors. Models have been developed for the two key analytes: glucose and lactate using Chinese hamster ovary (CHO) cell lines and using analyte specific information obtained from the feasibility studies. We observe slight model degradation for the multiplexed models in comparison to the conventional (single probe) models, decrease in r² values from 89.4% to 88% for glucose whereas for lactate from 92% to 91.8% and a simultaneous increase in the number of factors as the model incorporates the inter-probe variability, nevertheless the models were fit for purpose. The results of this particular application of implementing multiplexed-NIRS to monitor multiple bioreactor vessels are very encouraging, as successful models have been built on-line and validated externally, which proffers the prospect of reducing timelines in monitoring the vessels considerably, and in turn, providing improved control.     

WKB and MAF quantization rules for spatially confined quantum mechanical systems

A formalism is developed to obtain the energy eigenvalues of spatially confined quantum mechanical systems in the framework of the usual Wentzel–Kramers–Brillouin (WKB) and modified airy function (MAF) methods. To illustrate the working rule, the techniques are applied to three different cases, viz. the confined one‐dimensional harmonic and quartic oscillators and a boxed‐in charged particle subject to an external electric field. The energies thus obtained are compared with those from shifted 1/N expansion, variational, and other methods, as well as the available exact numerical results. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 497–504, 1999     

Computational modeling of heat transfer and sintering behavior during direct metal laser sintering of AlSi10Mg alloy powder

Direct Metal Laser Sintering (DMLS) is one of the leading additive manufacturing processes, which produces complex metallic parts directly from the powder. One of the major problems of this rapid manufacturing process is an inhomogeneous temperature distribution, which leads to residual stress in the build part. Thus, temperature analyses must be performed, to better understand the temperature distribution and sintering behavior of the powder bed with a different laser recipe. In this study, a comprehensive three-dimensional numerical model was developed to understand the temperature distribution during direct metal laser sintering of AlSi10Mg alloy powder. The computer simulation was carried out in ANSYS 17.0 platform. Further, the effect of process parameters such as laser power and scan speed on the temperature distribution and sintering behavior were studied. From the simulation results, it was found that, when the laser power increased from 70 W to 190 W, the maximum temperature of the molten pool increased from 731?°C to 2672?°C, and the molten pool length changed from 0.286 mm to 2.167 mm. A reverse phenomenon was observed with an increase in scan speed. The sintering depth of the powder layer increases significantly from 0.061 mm to 0.872 mm with increasing the applied laser power, but decreased from 0.973 mm to 0.209 mm as a higher scan speed was applied. The developed model helps to optimize the powder layer thickness and minimize the wastage of excess powders during the sintering process.     

Spontaneous symmetry breaking in static Robertson-Walker space-time with background charge

The finite-temperature ⁴ theory of static Robertson-Walker (RW) space-time is extended to a case with background charge. In contrast to earlier work on static RW space-time, the curvature term is retained and its effect on the effective potential and phase transition are explicitly calculated. The spontaneous symmetry breaking aspects and its dependence on various factors are discussed.