Homoserine Lactones,Methyl Oligohydroxybutyrates,and Other Extracellular Metabolites of Macroalgae‐Associated Bacteria of the Roseobacter Clade: Identification and Functions

Twenty‐four strains of marine Roseobacter clade bacteria were isolated from macroalgae and investigated for the production of quorum‐sensing autoinducers, N‐acylhomoserine lactones (AHLs). GC/MS analysis of the extracellular metabolites allowed us to evaluate the release of other small molecules as well. Nineteen strains produced AHLs, ranging from 3‐OH‐C10:0‐HSL (homoserine lactone) to (2E,11Z)‐C18:2‐HSL, but no specific phylogenetic or ecological pattern of individual AHL occurrence was observed when cluster analysis was performed. Other identified compounds included indole, tropone, methyl esters of oligomers of 3‐hydroxybutyric acid, and various amides, such as N‐9‐hexadecenoylalanine methyl ester (9‐C16:1‐NAME), a structural analogue of AHLs. Several compounds were tested for their antibacterial and antialgal activity on marine isolates likely to occur in the habitat of the macroalgae. Both AHLs and 9‐C16:1‐NAME showed high antialgal activity against Skeletonema costatum, whereas their antibacterial activity was low.     

Temperature Stability of Lead‐Free Niobate Piezoceramics with Engineered Morphotropic Phase Boundary

The temperature dependence of piezoelectric properties (direct piezoelectric coefficient d₃₃, converse piezoelectric coefficient d₃₃(E = 0), strain S and electromechanical coupling coefficient k_p) for two niobate‐based lead‐free piezoceramics have been contrasted. 0.92(Na_0.5K_0.5)NbO₃–0.02(Bi_1/2Li_1/2)TiO₃–0.06BaZrO₃ (6BZ/2BLT/92NKN) has a morphotropic phase boundary (MPB) between rhombohedral and tetragonal at room temperature and 0.92(Na_0.5K_0.5)NbO₃–0.03(Bi_1/2Li_1/2)TiO₃–0.05BaZrO₃ (5BZ/3BLT/92NKN) features an MPB engineered to be located below room temperature. At 30°C, d₃₃, d₃₃(E = 0), S (at 2 kV/mm), and k_p are 252 pC/N, 230 pm/V, 0.069%, 0.51 for 5BZ/3BLT/92NKN; and 348 pC/N, 380 pm/V, 0.106%, 0.57 for 6BZ/2BLT/92NKN, respectively. With increasing temperature, the piezoelectric properties decrease. At 200°C, d₃₃, d₃₃(E = 0), S (at 2 kV/mm), and k_p are 170 pC/N, 160 pm/V, 0.059%, 0.36 for 5BZ/3BLT/92NKN; and 181 pC/N, 190 pm/V, 0.061%, 0.39 for 6BZ/2BLT/92NKN. It is found that the electromechanical coupling coefficient has a better temperature stability than the piezoelectric coefficient in the studied system due to a large temperature‐dependent compliance change. The results demonstrate that engineering an MPB is highly effective in tailoring temperature stability of piezoceramics.     

Microstructure and phase composition of cordierite-based co-clinker

The aim of this work is to study the effect of phase composition and microstructure of cordierite-based co-clinkers on the electrical properties and coefficient of thermal expansion of cordierite briquettes. To achieve this aim talc and kaolinite samples were collected from quarries in the Egyptian desert. The samples are characterized using XRD, XRF, polarized light, cathodoluminescence and SEM microscopy attached with EDAX, in addition to X-ray micro-computed tomography (3D- µXCT). The electrical properties and coefficient of thermal expansion of the cordierite briquettes are determined using HiTESTER instrument and automatic Netzsch DIL402 PC dilatometer, respectively.Five talc-based batches were shaped and fired in the temperature range 1000–1350 °C for 2 h. The microstructural and physical characteristics of the resulted cordierite-based co-clinkers depend mainly on the viscosity of the liquid phase developed during firing. The microchemistry of the cordierite briquettes confirms their enrichment of both cordierite and ferroan-cordierite crystallized directly from locally developed melts. The dielectric constant and loss factor values for cordierite briquettes allow their possible use as insulator components in electronic applications.     

Long term stability of electrocaloric response in barium zirconate titanate

The stability of the electrocaloric effect under electric field cycling is an important consideration in the development of solid-state cooling devices. Here we report measurements carried out on Ba(Zr_0.2Ti_0.8)O₃ ceramics which reveal that the adiabatic temperature change, polarization-electric field hysteresis loops and dielectric permittivity/loss show stable behavior up to 10⁵ cycles. We further demonstrate that the loss in electrocaloric response observed after 10⁵ cycles is associated with the migration of oxygen vacancies. As a result, the electrical properties of the material are changed leading to an increase in leakage current and Joule heating. Reversing the polarity of the electric field after every 10⁵ cycles changes the migration direction of oxygen vacancies, thereby preventing charge accumulation at grain boundaries and electrodes. By doing so, the electrocaloric stability is improved and the adiabatic temperature remains constant even after 10⁶ cycles, much higher than achieved in commercially available barium titanate ceramics.     

Polyphenolrückgewinnung aus Olivenölabwasser durch Einsatz von Membrantechnologie

Olive mill wastewater (OMW) is obtained as byproduct of oil production in large quantities after the olive harvest, mainly in the Mediterranean region. One problem is the high load of organic matter, such as phytotoxic polyphenols, which causes significant environmental problems. However, due to their antioxidant properties the use of these polyphenols is also popular in several industry branches, e.g. production of plastics, cosmetics and drugs. A combined wastewater treatment permits besides water purification also recovery of the polyphenolic compounds for industrial use. One possibility is membrane technology. An overview of research studies concerning polyphenol recovery from OMW using membrane technologies is given.     

Mutation of Conserved Residues Increases in Vitro Activity of the Formylglycine‐Generating Enzyme

The formylglycine‐generating enzyme (FGE) recognizes proteins with a specific cysteine‐containing six‐amino‐acid motif and converts this cysteine residue into formylglycine. The resulting aldehyde function provides a unique handle for selective protein labeling. We have identified two mutations in FGE from Thermomonospora curvata that increase this catalytic efficiency more than 40‐fold. The resulting activity and stability, as well as its ease of recombinant production, make this FGE variant a practical reagent for in vitro protein engineering.