Thermally-stable high energy storage performances and large electrocaloric effect over a broad temperature span in lead-free BCZT ceramic

Ba_0.85Ca_0.15Zr_0.10Ti_0.90O₃ (BCZT) relaxor ferroelectric ceramics exhibit enhanced energy storage and electrocaloric performances due to their excellent dielectric and ferroelectric properties. In this study, the temperature-dependence of the structural and dielectric properties, as well as the field and temperature-dependence of the energy storage and the electrocaloric properties in BCZT ceramics elaborated at low-temperature hydrothermal processing are investigated. X-ray diffraction and Raman spectroscopy results confirmed the ferroelectric–paraelectric phase transition in the BCZT ceramic. At room temperature and 1 kHz, the dielectric constant and dielectric loss reached 5000 and 0.029, respectively. The BCZT ceramic showed a large recovered energy density (W_rec) of 414.1 mJ cm⁻³ at 380 K, with an energy efficiency of 78.6%, and high thermal-stability of W_rec of 3.9% in the temperature range of 340–400 K. The electrocaloric effect in BCZT was explored via an indirect approach following the Maxwell relation at 60 kV cm⁻¹. The significant electrocaloric temperature change of 1.479 K at 367 K, a broad temperature span of 87 K, an enhanced refrigerant capacity of 140.33 J kg⁻¹, and a high coefficient of performance of 6.12 obtained at 60 kV cm⁻¹ make BCZT ceramics potentially useful coolant materials in the development of future eco-friendly solid-state refrigeration technology.

Thermally-stable recovered energy density and significant electrocaloric temperature change over a broad temperature span in BCZT ceramic elaborated by low-temperature hydrothermal processing.     

Toxicity of copper oxide nanoparticle suspensions to aquatic biota

Toxicity effects induced by nanosuspensions of CuO (<50?nm; Sigma-Aldrich) on macrophytic algae cells of Nitellopsis obtusa (96-h median lethal concentration [LC50]), microphytic algae Chlorella (30-min median inhibitory concentration [IC50]), shrimp Thamnocephalus platyurus (24-h LC50), and rotifer Brachionus calyciflorus (24-h LC50) were investigated. No substantial differences between the effects of nonsonicated and sonicated nCuO suspensions were observed. The particle size distribution analysis accomplished by the laser diffraction technique at suspension concentration from 3 to 100?mg/L revealed rapid (within 5?min) reagglomeration of the particles after the sonication. The observed adverse effects on N. obtusa cells may be attributed to nanoparticles per se, but not to ionic Cu, because neither chemical analysis nor biological testing (algae survival in the supernatants of suspensions) confirmed the presence of cupric ions in toxic amounts. Contrary to ionic Cu form, nCuO delayed the initial phase of N. obtusa cell membrane depolarization. Lethality tests with rewash demonstrated that the least used 5-min exposure in 100?mg/L nCuO sonicated suspension induced 70% mortality in charophyte cells after 8?d, whereas the rewash after a short exposure to a noticeably toxic concentration of Cu(2+) prevented cell mortality. The obtained data suggested the possible influence of a thick charophyte cell wall on the dynamics of nanotoxicity effects.     

1H−15N HMBC NMR as a tool for rapid identification of isomeric azaindoles: The case of 5F‐MDMB‐P7AICA

The high frequency of the synthetic cannabinoid receptor agonists (SCRAs) emergence renders this group of new psychoactive compounds particularly demanding in terms of detection, identification, and responding. Without the available reference material, one of the specific problems is differentiation and structure elucidation of constitutional isomers. Herein, we report a simple and efficient flow chart diagram applicable for a rapid nuclear magnetic resonance (NMR) identification and differentiation between azaindoles, 4‐, 5‐, 6‐, and 7‐azaindole, which is a common structural motif of synthetic cannabinoids. The flow chart diagram is based on ¹H NMR and ¹H–¹⁵N NMR spectra, and to prove the concept, it has been tested on 5F‐MDMB‐P7AICA ( 1 ). Spectral and analytical data including standard 1D and 2D NMR spectra, gas chromatography?mass spectrometry (GC?MS), Fourier transform infrared?attenuated total reflectant (FTIR?ATR), Raman, melting point, and combustion analysis are provided for compound 1 .     

Variation of vlhA gene in Mycoplasma synoviae clones isolated from chickens

Mycoplasma synoviae synthesizes haemagglutinin VlhA, which cleaves into the N-terminal part, a lipoprotein MSPB, and a C-terminal part MSPA. Previous studies have shown that the 3′-end of the expressed vlhA gene can recombine with vlhA pseudogenes in a process called gene conversion, but there have been no data about diversification of the expressed vlhA gene in M. synoviae populations replicating in chickens. Following intratracheal inoculation with the M. synoviae strain ULB 02/T6, which showed only minor vlhA gene variation prior to inoculation, we investigated temporal changes in MSPB epitopes defined by monoclonal antibodies (mAbs) 3B4 and 50, as well as diversification of the vlhA gene sequence in M. synoviae populations recovered from chicken tracheas. In cultures isolated 8 and 18 days post inoculation (p.i.), most colonies showed variation of MSPB epitopes for mAbs 3B4 and 50. They also changed 3′-end vlhA gene sequences. Further diversity of the vlhA gene occurred in cultures isolated 8 weeks and 5 months p.i. The vlhA gene sequences from isolated cultures shared only 65 to 80% sequence identity with vlhA gene of the inoculated ULB 02/T6 culture. Notably, in most of those cultures their vlhA gene sequences contained stop codons potentially causing premature terminations of translation. Interestingly, in one culture isolated 8 weeks p.i. (clone T6-8W/IT2A) the 3′-vlhA gene sequence was identical in the last 1140 bases to that of the first vlhA pseudogene positioned the most far (upstream) of the expressed vlhA gene. This is the first demonstration of temporal diversity of the vlhA gene in M. synoviae populations isolated from chicken tracheas.     

Solvent and mutation effects on the nucleation of amyloid beta-protein folding

Experimental evidence suggests that the folding and aggregation of the amyloid beta-protein (Abeta) into oligomers is a key pathogenetic event in Alzheimer's disease. Inhibiting the pathologic folding and oligomerization of Abeta could be effective in the prevention and treatment of Alzheimer's disease. Here, using all-atom molecular dynamics simulations in explicit solvent, we probe the initial stages of folding of a decapeptide segment of Abeta, Abeta(21-30), shown experimentally to nucleate the folding process. In addition, we examine the folding of a homologous decapeptide containing an amino acid substitution linked to hereditary cerebral hemorrhage with amyloidosis-Dutch type, [Gln-22]Abeta(21-30). We find that: (i) when the decapeptide is in water, hydrophobic interactions and transient salt bridges between Lys-28 and either Glu-22 or Asp-23 are important in the formation of a loop in the Val-24-Lys-28 region of the wild-type decapeptide; (ii) in the presence of salt ions, salt bridges play a more prominent role in the stabilization of the loop; (iii) in water with a reduced density, the decapeptide forms a helix, indicating the sensitivity of folding to different aqueous environments; and (iv) the "Dutch" peptide in water, in contrast to the wild-type peptide, fails to form a long-lived Val-24-Lys-28 loop, suggesting that loop stability is a critical factor in determining whether Abeta folds into pathologic structures.     

Folding events in the 21-30 region of amyloid beta-protein (Abeta) studied in silico

Oligomeric assemblies of the amyloid beta-protein (Abeta) have been implicated in the pathogenesis of Alzheimer's disease as a primary source of neurotoxicity. Recent in vitro studies have suggested that a 10-residue segment, Ala-21-Ala-30, forms a turn-like structure that nucleates the folding of the full-length Abeta. To gain a mechanistic insight, we simulated Abeta(21-30) folding by using a discrete molecular dynamics algorithm and a united-atom model incorporating implicit solvent and a variable electrostatic interaction strength (EIS). We found that Abeta(21-30) folds into a loop-like conformation driven by an effective hydrophobic attraction between Val-24 and the butyl portion of the Lys-28 side chain. At medium EIS [1.5 kcal/mol (1 cal = 4.18 J)], unfolded conformations almost disappear, in agreement with experimental observations. Under optimal conditions for folding, Glu-22 and Asp-23 form transient electrostatic interactions (EI) with Lys-28 that stabilize the loop conformations. Glu-22-Lys-28 is the most favored interaction. High EIS, as it occurs in the interior of proteins and aggregates, destabilizes the packing of Val-24 and Lys-28. Analysis of the unpacked structures reveals strong EI with predominance of the Asp-23-Lys-28 interaction, in agreement with studies of molecular modeling of full-length Abeta fibrils. The binary nature of the EI involving Lys-28 provides a mechanistic explanation for the linkage of amino acid substitutions at Glu-22 with Alzheimer's disease and cerebral amyloid angiopathy. Substitutions may alter the frequency of Glu-22 or Asp-23 involvement in contact formation and affect the stability of the folding nucleus formed in the Abeta(21-30) region.     

Mineralization of polyurethane membranes in the total artificial heart (TAH): a retrospective study from long-term animal experiments

The degree of mineralization of TAH membranes in animals is directly related to the survival time of animals with a TAH. Large differences in mineralization of the membranes among individual animals have been observed. These differences can be explained by the simultaneous presence of infection on biomaterials (polyurethane) as well as by different levels of natural inhibitors of mineralization. No positive influence of applying sodium warfarin for the inhibition of the mineralization was observed.     

Computer simulations of Alzheimer's amyloid beta-protein folding and assembly

Pathological folding and aggregation of the amyloid beta-protein (Abeta) are widely perceived as central to understanding Alzheimer's disease (AD) at the molecular level. Experimental approaches to study Abeta self-assembly are limited, because most relevant aggregates are quasi-stable and inhomogeneous. In contrast, simulations can provide significant insights into the problem, including specific sites in the molecule that would be attractive for drug targeting and details of the assembly pathways leading to the production of toxic assemblies. Here we review computer simulation approaches to understanding the structural biology of Abeta. We discuss the ways in which these simulations help guide experimental work, and in turn, how experimental results guide the development of theoretical and simulation approaches that may be of general utility in understanding pathologic protein folding and assembly.