Polylactide‐perylene derivative for blue biodegradable organic light‐emitting diodes

In this work we demonstrate, for the first time, the use of polylactic acid (PLA) as a biodegradable host matrix for the construction of the active emissive layer of organic light‐emitting diode (OLED) devices for potential use in bioelectronics. In this preliminary study, we report a robust synthesis of two fluorescent PLA derivatives, pyrene‐PLA ( AH10 ) and perylene‐PLA ( AH11 ). These materials were prepared by the ring opening polymerisation of l ‐lactide with hydroxyalkyl‐pyrene and hydroxyalkyl‐perylene derivatives using 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as catalyst. OLEDs were fabricated from these materials using a simple device architecture involving a solution‐processed single‐emitting layer in the configuration ITO/PEDOT:PSS/PVK:OXD‐7 (35%): AH10 or AH11 (20%)/TPBi/LiF/Al (ITO, indium tin oxide; PEDOT:PSS, poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonic acid); PVK, poly(vinylcarbazole); OXD‐7, (1,3‐phenylene)‐bis‐[5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole]; TPBi, 2,2′,2″‐(1,3,5‐benzenetriyl)tris(1‐phenyl‐1H‐benzimidazole)). The turn‐on voltage for the perylene OLED at 10 cd m^–2 was around 6 V with a maximum brightness of 1200 cd m^–2 at 13 V. The corresponding external quantum efficiency and device current efficiency were 1.5% and 2.8 cd A^–1 respectively. In summary, this study provides proof of principle that OLEDs can be constructed from PLA, a readily available and renewable bio‐source. © 2020 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.     

Highly disordered ionic distribution in α-dicalcium silicate for structure relaxation

Dicalcium silicate, which is found in steelmaking slag for dephosphorization, exists as the hexagonal α phase at high temperatures. The α-dicalcium silicate forms a solid solution with tricalcium phosphate in the entire composition range, although the reason for high solubility of phosphorus remains unclear in view of the crystal structure. It has previously been reported that the crystal structure of α-dicalcium silicate consists of a symmetric arrangement of Ca²⁺ ions and SiO₄⁴⁻ tetrahedra, although other polymorphs exhibit asymmetric arrangements. However, because the occupation probability of each atomic site in the α polymorph is not limited to unity, it has not been qualified how these ions are exactly arranged. In this study, the ionic distribution in the α polymorph of dicalcium silicate was evaluated by first-principles calculation based on density functional theory (DFT), as well as by molecular dynamics (MD) simulation with a polarizable ion model optimized by DFT calculation. The results indicated that the completely symmetric ionic arrangement, as reported for the α phase, is the most unstable. Electronic-state calculation and MD simulation indicated that a highly disordered ionic arrangement spontaneously forms in the α-phase crystal for structure relaxation when held at high temperatures, or when phosphorus is incorporated.     

In situ synthesis of Al2O3–SiC powders via molten-salt-assisted aluminum/carbothermal reduction method

Al₂O₃–SiC composite powder (ASCP) was successfully synthesized using a novel molten-salt-assisted aluminum/carbothermal reduction (MS-ACTR) method with silica fume, aluminum powder, and carbon black as raw materials; NaCl–KCl was used as the molten salt medium. The effects of the synthesis temperature and salt-reactant ratio on the phase composition and microstructure were investigated. The results showed that the Al₂O₃–SiC content increased with an increase in molten salt temperature, and the salt–reactant ratio in the range of 1.5:1–2.5:1 had an impact on the fabrication of ASCP. The optimum condition for synthesizing ASCP from NaCl–KCl molten salt consisted of maintaining the temperature at 1573 K for 4 h. The chemical reaction thermodynamics and growth mechanism indicate that the molten salt plays an important role in the formation of SiC whiskers by following the vapor-solid growth mode in the MS-ACTR treatment. This study demonstrates that the addition of molten salt as a reaction medium is a promising approach for synthesizing high-melting-point composite powders at low temperatures.     

Ammonia production using iron nitride and water as hydrogen source under mild temperature and pressure

Ammonia generation was studied in the reaction between water and nitrogen-containing iron at 323 K and atmospheric pressure. Similar to metallic Fe, the interstitial compound Fe₃N reduced water through Fe oxidation to produce hydrogen gas, while the N combined with atomic hydrogen to produce ammonia as a byproduct. The addition of carbon dioxide to this system accelerated the reaction with concomitant consumption of carbon dioxide. The promoted ammonia production upon addition of carbon dioxide can be attributed to the generation of atomic hydrogen from the redox reaction of carbonic acid and Fe, as well as removal of used Fe from the reaction system through the formation of a soluble carbonato complex. When carbonate was added to the reaction system, the production rates of ammonia and hydrogen increased further. The results here confirmed that ammonia can be synthesized from iron nitride under mild conditions by utilizing carbon dioxide.     

Single chamber Solid Oxide Fuel Cells selective electrodes: A real chance with brownmillerite-based nanocomposites

In this contribution brownmillerite-based nanocomposite cathode for Single-Chamber Solid Oxide Fuel Cells is developed. These cells can be very attractive especially for small and cheap devices because of the absence of seals. The efficiency of SC-SOFCs is strictly connected to the selectivity of anode and cathode, the bottleneck for this technology. The development of a cathode inert in fuel oxidation is particularly challenging. Our strategy is to start from a catalytically un-active support (CFA = Ca₂FeAl_0.95Mg_0.05O₅) and induce the formation of iron oxide based nanoparticles, expected to activate oxygen. Symmetric (CFA + FeO_x/CGO/CFA + FeO_x) and complete cells (CFA + FeO_x/CGO/Ni-CGO) are studied in air and methane/oxygen 2:1 mixture. The Area Specific Resistance of CFA + FeO_x is less than 1/3 that of CFA. The high selectivity allows to reach an efficiency of 25%; power still needs to be increased but we demonstrated the possibility to develop selective low cost electrodes. The effect of air, methane/oxygen exposure and the heat treatments were carefully investigated.     

Cell-envelope proteinases from lactic acid bacteria: Biochemical features and biotechnological applications

Proteins displayed on the cell surface of lactic acid bacteria (LAB) perform diverse and important biochemical roles. Among these, the cell-envelope proteinases (CEPs) are one of the most widely studied and most exploited for biotechnological applications. CEPs are important players in the proteolytic system of LAB, because they are required by LAB to degrade proteins in the growth media into peptides and/or amino acids required for the nitrogen nutrition of LAB. The most important area of application of CEPs is therefore in protein hydrolysis, especially in dairy products. Also, the physical location of CEPs (i.e., being cell-envelope anchored) allows for relatively easy downstream processing (e.g., extraction) of CEPs. This review describes the biochemical features and organization of CEPs and how this fits them for the purpose of protein hydrolysis. It begins with a focus on the genetic organization and expression of CEPs. The catalytic behavior and cleavage specificities of CEPs from various LAB are also discussed. Following this, the extraction and purification of most CEPs reported to date is described. The industrial applications of CEPs in food technology, health promotion, as well as in the growing area of water purification are discussed. Techniques for improving the production and catalytic efficiency of CEPs are also given an important place in this review.     

A method of assessing essential amino acid availability from microbial and ruminally undegraded protein in lactating dairy cows

The objective of this study was to extend a stable isotope-based assessment of AA absorption from rumen-degradable protein (RDP) sources to include determination of essential AA (EAA) availability from microbial protein (MCP). To demonstrate the technique, a study using a 2 × 2 factorial arrangement of treatments applied in a repeated 4 × 4 Latin square design was undertaken. Factors were high and low rumen-degradable protein and high and low starch. Twelve lactating cows were blocked into 3 groups according to days in milk and randomly assigned to the 4 treatment sequences. Each period was 14 d in length with 10 d of adaption followed by 4 d of ruminal infusions of ¹⁵N-labeled ammonium sulfate. On the last day of each period, a ¹³C-labeled AA mixture was infused into the jugular vein over a 6-h period to assess total AA entry. Rumen, blood, urine, and milk samples were collected during the infusions. Ruminal bacteria and blood samples were assessed for AA enrichment. Total plasma AA absorption rates were derived for 6 EAA from plasma ¹³C AA enrichment. Absorption of 6 EAA from MCP was calculated from total AA absorption based on ¹⁵N enrichment in blood and rumen bacteria. Essential AA absorption rates from total protein, MCP, and rumen-undegradable protein were derived with standard errors of the mean of 6, 14, and 14%, respectively. An average of 45% of absorbed EAA were from MCP, which varied among 6 EAA and was interactively affected by starch and RDP in diets. Microbial AA availability measured by isotope dilution method increased with the high RDP diets and was unaffected by starch level, except for Met, which decreased with high starch. Microbial protein outflow, estimated from urinary purine derivatives, increased with RDP and was not significantly affected by starch. This was consistent with measurements from the isotope dilution method. Total AA absorption rates measured from isotope dilution were similar to estimates from CNCPS (v. 6.55), but a lower proportion of absorbed AA was derived from MCP for the former method. Compared with the isotope and CNCPS estimates, the Fleming model underestimated microbial EAA and total EAA availability. An average of 58% of the absorbed EAA was converted into milk, which varied among individual AA and was interactively affected by starch and RDP in diets. The isotope dilution approach is advantageous because it provides estimates of EAA availability for individual EAA from rumen-undegradable protein and MCP directly with fewer errors of measurement than can be achieved with intestinal disappearance methods.     

Gelatinised and hydrolysed corn starch is a cost-effective carbon source with higher production of L-lactic acid by Bacillus coagulans compared with glucose

L-lactic acid is an important organic acid widely used in pharmaceutical, food and textile industries. Bacillus coagulans BCS13002 can efficiently produce L-lactic acid with two kinds of carbon sources. BCS13002 produced L-lactic acid at a content of 10.23 ± 0.16 g/L and 11.67 ± 0.22 g/L, when glucose and gelatinised and hydrolysed corn starch （GHCS） were used, respectively. GHCS exhibits several advantages, including high yield of L-lactic acid and low cost. Proteomics analyses identified several key enzymes, which contributed to the higher production of L-lactic acid when GHCS was used as the carbon source. Those key enzymes were involved in the two-component system (SpoOF), pantothenate and CoA biosynthesis (pantothenate synthetase, 1.584-fold; dihydroxy-acid dehydratase, 1.517-fold), beta-alanine metabolism (1.605-fold) and valine, leucine and isoleucine biosynthesis (1.517-fold) pathways. This study provides a biological basis for using GHCS as a substitute of glucose in the production of L-lactic acid.     

Rate equation theory for the hydrogenation kinetics of Mg-based materials

A uniform solid product layer normally assumed in the shrinking-core model cannot predict the kinetic transition behavior of the H₂ adsorption reactions. In this study, the concept of a uniform solid product layer has been replaced by that of the inward growth of solid products on the solid surface. A rate equation is established to calculate the inward growth of the solid product and was implemented into the shrinking-core model to calculate the H₂ adsorption kinetics for various shapes of Mg-based materials. The prediction accuracy of the developed model is verified from the detailed experimental data. To account for the external gas diffusion around the particle and the intraparticle gas diffusion, an analytical equation is derived using the Thiele modulus method. This model can be used to analyze various kinetic aspects and to analyze the effect of change in the particle microstructure on intraparticle diffusion.     

Validating the efficiency of γ-Al2O3/La0.6Sr0.4Co0.2Fe0.8O3-δ double-layer electrolyte for low temperature solid oxide fuel cell

Perovskite La_0.6Sr_0.4Co_0.2Fe_0.8O_3+δ (LSCF) as a promising cathode material possessed overwhelming electronic conduction along with certain ionic conductivity. Its strong electron conduction capability hinder the application of pure-phase LSCF as electrolyte in semiconductor membrane fuel cell (SMFC). In order to constrain the electron transport and take advantage of the decent ion conduction of LSCF, a thin layer of γ-Al₂O₃ with insulating property was added as an electron barrier layer and combine with LSCF to form a two-layer structure electrolyte. Through adjusting the weight ratio of LSCF/γ-Al₂O₃ to optimize the thickness of double layers, an open circuit voltage of 0.98 V and a maximum power density of 690 mW/cm² was received at 550 °C. At the same time, SEM, EIS and other characterization technology had proven that the LSCF/γ-Al₂O₃ bi-layer electrolyte can work efficiently at low temperature. The advantage of this work is the application of double-layer (γ-Al₂O₃/LSCF) structure electrolyte to instead of mixed material electrolyte in low-temperature solid oxide fuel cells. Structural innovation and the using of insulating materials provided clues for the further development of SMFC.