The first biosynthetic studies of the azinomycins: acetate incorporation into azinomycin B

13C-labelled acetate efficiently labels the antitumour natural product azinomycin B, revealing a polyketide origin for the naphthoate fragment, that threonine is the probable precursor of the enol fragment, and that alpha-ketoglutarate is a probable precursor of the aziridine fragment.     

Silver incorporation into cathodes for solid oxide fuel cells operating at intermediate temperature

Silver (Ag) at 0.1–2.0 wt% was incorporated into cathodes for solid oxide fuel cells as a catalyst for oxygen reduction. A novel processing route for Ag incorporation ensuring a very homogeneous Ag ion distribution is presented. From the results of X-ray powder diffraction it can be concluded that the La_0.65Sr_0.3MnO_3– perovskite phase is already formed at 900 °C. The solubility of Ag in the crystal lattice in this type of perovskite was below 1 wt%. The electrochemical tests of these materials show that there is only a slight catalytic effect of Ag. Scanning electron microscopy reveals a low mechanical contact of the cathode grains to the electrolyte due to the low cathode sintering temperature that was chosen.     

A new interpretation of Hund's first rule

The diagonal elements of the first and second order spinless density matrices have been calculated for the lowest excited¹ P and³ P terms of Be, B⁺ and C⁺⁺ using wavefunctions at different levels of approximations published in the literature. The analysis of these functions has resulted in a new interpretation of Hund's first rule in terms of an anisotropic screening effect.     

Critical challenges and progress of solid garnet electrolytes for all-solid-state batteries

Significant safety problems and poor cyclic stability of conventional lithium-ion batteries, which based on organic liquid electrolytes, hinder their practical application, while all-solid-state batteries (ASSBs) are considered the most promising candidates to replace traditional lithium-ion batteries. As a critical component of ASSBs, solid-state electrolytes play an essential role in ion transport properties and stability. At present, the solid garnet electrolyte is considered as one of the most promising electrolytes because of its excellent performance. However, it still faces many challenges in ionic conductivity, air stability, electrode/electrolyte interface, and lithium dendrites. Therefore, this review is concerned about the up-to-date progress and challenges which will greatly influence the large-scale application of solid garnet electrolytes. Firstly, various ways to improve the ionic conductivity of solid garnet electrolytes are comprehensively summarized. Then, the stability of solid garnet electrolytes in the air is carefully discussed. Secondly, the latest progress in interface engineering between anode/cathode and solid garnet electrolytes treated by different methods is reported. The formation mechanism and influencing factors of lithium dendrites in the solid garnet electrolyte are systematically focused on. Finally, the development and innovation of composite solid garnet electrolytes and 3D garnet electrolytes are summarized in detail. Some important characterization techniques for studying the aforementioned problems are also summarized. Based on the current development of solid garnet electrolytes and solid-state batteries, further challenges and perspectives are presented.     

Control of Dopant Adsorption from Aqueous Solution into Nanoporous Sol-Gel Films

The doping of porous sol-gel films by adsorption of cations onto silica from aqueous solutions is demonstrated. The films are fabricated using the sol-gel method, giving nanometer scale porosity, high surface area, and homogeneity on the scale of optical wavelengths. After deposition by spin coating and initial heat treatment, the films are soaked in a salt solution of the desired dopant, and then given a further consolidating heat treatment.Doping with lead, aluminum and calcium has been demonstrated, and consistent and reproducible processes have been established. Results are presented showing control of doping level through pre-doping temperature and surface treatment, doping time and temperature, and doping solution pH. Potential applications in integrated optics are proposed.     

Laser-induced breakdown spectroscopy of solid aerosols produced by optical catapulting

Laser-induced breakdown spectroscopy of particles ejected by optical catapulting is discussed for the first time. For this purpose, materials deposited on a substrate were ejected and transported from the surface in the form of a solid aerosol by optical catapulting using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser at 1064 nm. A Q-switched Nd:YAG laser at 532 nm was used for chemical characterization of the particles by laser-induced breakdown spectroscopy. Both lasers were synchronized in order to perform suitable spectral detection. The optical catapulting was optimized and evaluated using aluminum silicate particles, nickel spheres, and quartz and stainless steel particles. Experimental parameters such as the interpulse delay time, the sampling distance, the laser fluence, the sampling rate and the particle size have been studied. A correlation between these parameters and the particle size is reported and discussed.     

Controlled incorporation of deuterium into bacterial cellulose

Isotopic enrichment has been widely used for investigating the structural and dynamic properties of biomacromolecules to provide information that cannot be carried out with molecules composed of natural abundance isotopes. A media formulation for controlled incorporation of deuterium in bacterial cellulose synthesized by Gluconacetobacter xylinus subsp. sucrofermentans is reported. The purified cellulose was characterized using Fourier Transform Infra-Red spectrophotometry and mass spectrometry which revealed that the level of deuterium incorporation in the perdeuterated cellulose was greater than 90 %. Small-angle neutron scattering analysis demonstrated that the overall structure of the cellulose was unaffected by the substitution of deuterium for hydrogen. In addition, by varying the amount of D-glycerol in the media it was possible to vary the scattering length density of the deuterated cellulose. A large disk model was used to fit the curves of bacterial cellulose grown using 0 and 100 % D-Glycerol yielding a lower bound to the disk radii, R _min = 1,132 ± 6 and 1,154 ± 3 Å and disk thickness, T = 128 ± 1 and 83 ± 1 Å for the protiated and deuterated forms of the bacterial cellulose, respectively. This agrees well with the scanning electron microscopy analysis which revealed stacked sheets in the cellulose pellicles. Controlled incorporation of deuterium into cellulose will enable new types of experiments using techniques such as neutron scattering to reveal information about the structure and dynamics of cellulose and its interactions with proteins and other (bio) polymers.     

Thermodynamic stability of calcium vanadium garnet ferrites upon formation of substitutional solid solutions

The thermodynamic stability of calcium vanadium garnet ferrites Ca₃Fe_{3.5 ? x} Ti_2x V_{1.5 ? x} O₁₂ upon isomorphic substitution of titanium ions for iron and vanadium ions was studied by the EMF method using ZrO₂(Y₂O₃) ceramic solid electrolyte. Temperature-dependent ΔG ⁰ was determined. Isomorphic substitutions of titanium ions for iron and vanadium ions in the inequivalent sublattices of the garnet structure in a temperature range of 1100–1483 K cause changes in ΔG ⁰ due to the entropy and enthalpy components and has a minimal value when x = 0.15.     

Transpeptidase-mediated incorporation of D-amino acids into bacterial peptidoglycan

The β-lactams are the most important class of antibiotics in clinical use. Their lethal targets are the transpeptidase domains of penicillin binding proteins (PBPs), which catalyze the cross-linking of bacterial peptidoglycan (PG) during cell wall synthesis. The transpeptidation reaction occurs in two steps, the first being formation of a covalent enzyme intermediate and the second involving attack of an amine on this intermediate. Here we use defined PG substrates to dissect the individual steps catalyzed by a purified E. coli transpeptidase. We demonstrate that this transpeptidase accepts a set of structurally diverse D-amino acid substrates and incorporates them into PG fragments. These results provide new information on donor and acceptor requirements as well as a mechanistic basis for previous observations that noncanonical D-amino acids can be introduced into the bacterial cell wall.     

The kinetics of incorporation of111In into m-tetraphenylporphine

An improved method is described for rapidly incorporating “carrier-free”¹¹¹In into m-tetraphenylporphine to produce a lipid soluble complex of potential clinical usefulness. The reaction in glacial acetic acid is temperature dependent and markedly sensitive to the nature of the anion present. Halide ions completely inhibit incorporation of the¹¹¹In. An unusual destruction of the porphyrin ring by nitrate in glacial acetic acid is reported. Presented in part at the 2nd Int. Symp. on Radiopharmaceutical Chemistry, July 1978, Oxford, England.     

The first framework solid composed of vanadosilicate clusters

In this Communication, we report the first example of a network structure composed of vanadosilicate clusters. We utilized hydrothermal conditions to synthesize a polyoxovanadogermanate (POVG): (C4H14N2)4[V14O44(GeOH)8].6H2O. By substituting SiO2 for GeO2 in the synthesis, a framework solid, H4V18O46(SiO)8C4H12N2)4.(H2O)] .4H2O, is formed in which isostructural vanadosilicate clusters are linked by five-coordinate vanadium with a (VO)O2N2 environment. The charge-compensating organic amine, 1,4-diaminobutane, in the POVG is covalently bonded to the linking vanadium polyhedra in the framework solid.     

Mössbauer studies of iron incorporation into ferritins

Iron(III) monomers, dimers and clusters have been identified by Mössbauer spectroscopy during the initial stages of iron incorporation into ferritins, following Fe(II) oxidation. Iron(III) monomers seem to arise from dimer dissociation. Some of the monomers are transferred from iron poor to iron rich ferritin molecules, where they join the iron core clusters. Horse spleen ferritin, several variants of human H chain ferritin andEscherichia coli ferritin (Ec-FTN) can all accept the iron from human H chain ferritin. The small iron cores of Ec-FTN are different from those of mammalian ferritins, which indicates that the structure of the iron core depends on the protein shell.     

Microscopic visualization of alamethicin incorporation into model membrane monolayers

Lipid interactions and cooperative assembly properties are fundamental determinants for the action of antimicrobial membrane-active peptides. Here we analyze the interactions and aggregation properties of alamethicin, an antimicrobial pore-forming peptide, with films formed at the air/water interface. Surface-area/pressure isotherms, Brewster angle microscopy, and fluorescence-confocal microscopy provided detailed information on the morphologies and structural properties of the peptide and its effect on the film components. The pressure-area analysis and microscopy experiments facilitated unprecedented visualization of the structural consequences of alamethicin association at the air/water interface, with pure phospholipid films, and within mixed phospholipid/polydiacetylene (PDA) films. The analysis exposed the kinetic features and the interplay between the peptide aggregates and film constituents. In particular, the results demonstrate the use of phospholipid/PDA film assemblies for studying membrane-peptide association and interactions within two-dimensional films.     

Selective incorporation of functional dicarboxylates into zinc metal-organic frameworks

Zinc(II) nitrate reacts with different ratios of 1,4-benzenedicarboxylic acid (H(2)bdc) and 2-halo-1,4-benzenedicarboxylic acid (H(2)bdc-X, X = Br or I) to give [Zn(4)O(bdc)(3-x)(bdc-X)(x)], in which preferential incorporation of bdc is observed. The selective incorporation is related to crystal growth rates, and the proportion of incorporated bdc-X rises with increasing reaction time.     

Lipid composition-dependent incorporation of multiple membrane proteins into liposomes

Membrane proteins from bacteria Pasteurella multocida were used as a model for studying its incorporation into liposomes. An important step to achieve efficient high yield protein incorporation in proteoliposomes is the study of the more suitable lipid composition. To this end, we compared the amount of total protein, reconstituted by co-solubilization methods, into liposomes of phospholipids with different polar head groups and acyl chain lengths. The liposomes and proteoliposomes were characterised by isopycnic centrifugation in sucrose gradient and by dynamic light scattering. Experimental and theoretical results were compared considering the effects exerted through the hydrocarbon chain length, volume, and optimal cross-sectional area of the phospholipid (combined in the geometrical critical packing parameter, lipid–protein matching), critical spontaneous radius of curvature of the bilayer vesicle, phase transition temperature of the lipid and ratio of lipid–protein molecules present in the vesicles. The highest incorporation of multiple proteins was found with dipalmitoylphosphatidylcholine (DPPC), reaching a yield of 93% compared to the lower relative amounts incorporated in proteoliposomes of the other lipids. The incorporation of multiple proteins induces a proportional enhancement of vesicular dimension, since DPPC–proteoliposomes have an average diameter of 1850 Å, compared to the 1430 Å for pure DPPC vesicles.