Highly Stable Operation of Lithium Metal Batteries Enabled by the Formation of a Transient High‐Concentration Electrolyte Layer

Lithium (Li) metal has been extensively investigated as an anode for rechargeable battery applications due to its ultrahigh theoretical specific capacity and the lowest redox potential. However, significant challenges including dendrite growth and low Coulombic efficiency are still hindering the practical applications of rechargeable Li metal batteries. It is demonstrated that long‐term cycling of Li metal batteries can be realized by the formation of a transient high‐concentration electrolyte layer near the surface of Li metal anode during high rate discharge process. The highly concentrated Li⁺ ions in this transient layer will immediately be solvated by the available solvent molecules and facilitate the formation of a stable and flexible solid electrolyte interphase (SEI) layer composed of a poly(ethylene carbonate) framework integrated with other organic/inorganic lithium salts. This SEI layer largely suppresses the corrosion of Li metal anode attacked by free organic solvents and enables the long‐term operation of Li metal batteries. The fundamental findings in this work provide a new direction for the development of Li metal batteries that could be operated at high current densities for a wide range of applications.     

Percutaneous closure of a left atrial appendage with relevant suture dehiscence

Atrial fibrillation is a widespread disease and highly relevant as it carries an extended risk for ischaemic stroke. Surgical closure of the left atrial appendage is routinely performed during open heart surgery in patients with atrial fibrillation with the aim of thromboembolic protection. In this report we present a successful percutaneous closure of a left atrial appendage, which showed clinically relevant suture dehiscence several years after surgical closure.     

Failure Mechanism for Fast‐Charged Lithium Metal Batteries with Liquid Electrolytes

In recent years, the Li metal anode has regained a position of paramount research interest because of the necessity for employing Li metal in next‐generation battery technologies such as Li‐S and Li‐O₂. Severely limiting this utilization, however, are the rapid capacity degradation and safety issues associated with rechargeable Li metal anodes. A fundamental understanding of the failure mechanism of Li metal at high charge rates has remained elusive due to the complicated interfacial chemistry that occurs between Li metal and liquid electrolytes. Here, it is demonstrated that at high current density the quick formation of a highly resistive solid electrolyte interphase (SEI) entangled with Li metal, which grows towards the bulk Li, dramatically increases up the cell impedance and this is the actual origin of the onset of cell degradation and failure. This is instead of dendritic or mossy Li growing outwards from the metal surface towards/through the separator and/or the consumption of the Li and electrolyte through side reactions. Interphase, in this context, refers to a substantive layer rather than a thin interfacial layer. Discerning the mechanisms and consequences for this interphase formation is crucial for resolving the stability and safety issues associated with Li metal anodes.     

Genome Duplication in Soybean (Glycine Subgenus Soja)

Restriction fragment length polymorphism mapping data from nine populations (Glycine max X G. soja and G. max X G. max) of the Glycine subgenus soja genome led to the identification of many duplicated segments of the genome. Linkage groups contained up to 33 markers that were duplicated on other linkage groups. The size of homoeologous regions ranged from 1.5 to 106.4 cM, with an average size of 45.3 cM. We observed segments in the soybean genome that were present in as many as six copies with an average of 2.55 duplications per segment. The presence of nested duplications suggests that at least one of the original genomes may have undergone an additional round of tetraploidization. Tetraploidization, along with large internal duplications, accounts for the highly duplicated nature of the genome of the subgenus. Quantitative trait loci for seed protein and oil showed correspondence across homoeologous regions, suggesting that the genes or gene families contributing to seed composition have retained similar functions throughout the evolution of the chromosomes.     

Integrin ß1 polymorphisms and bleeding risk after coronary artery stenting

Bleeding complications following percutaneous coronary intervention associate with increased mortality. However, the underlying molecular mechanisms are insufficiently understood. Platelet recruitment and activation at sites of vascular injury depends on the function of integrin adhesion receptors. Besides GPIIbIIIa as the most abundant integrin receptor, platelets relevantly express ß1 integrins. Experimental evidence from in vivo studies suggests a significant role of ß1 integrins in primary haemostasis. However, little is known about the clinical impact of genetic alterations of the β1 subunit, which might contribute to bleeding complications in patients. In this study, we performed DNA sequencing of patients suffering from bleeding complications after coronary artery stenting according to TIMI or BARC classification. We isolated DNA samples from 741 patients out of a cohort from 14,160 patients recruited in seven randomized clinical trials between June 2000 and May 2011. Subsequently, Sanger sequencing was performed covering the β1 integrin cytoplasmic activation domain (exon16) and its non-coding upstream region. Out of 764 patients suffering from bleeding complications, 741 DNA samples were successfully sequenced. Genotype variation was detected for SNP rs2153875 located within the non-coding upstream region with following allele frequency in study population: CC (7.3%), CA (35%) and AA (57.8%), which is similar to a general population cohort. Further, genotype variation in SNP rs2153875 do not associate with the frequency of TIMI or BARC classified access or non-access site bleedings. Genotype variations of the β1 integrin activation domain do not associate with bleeding risk after PCI.

     

Ral-GTPase influences the regulation of the readily releasable pool of synaptic vesicles

The Ral proteins are members of the Ras superfamily of GTPases. Because they reside in synaptic vesicles, we used transgenic mice expressing a dominant inhibitory form of Ral to investigate the role of Ral in neurosecretion. Using a synaptosomal secretion assay, we found that while K(+)-evoked secretion of glutamate was normal, protein kinase C-mediated enhancement of glutamate secretion was suppressed in the mutant mice. Since protein kinase C effects on secretion have been shown to be due to enhancement of the size of the readily releasable pool of synaptic vesicles docked at the plasma membrane, we directly measured the refilling of this readily releasable pool of synaptic vesicles after Ca(2+)-triggered exocytosis. Refilling of the readily releasable pool was suppressed in synaptosomes from mice expressing dominant inhibitory Ral. Moreover, we found that protein kinase C and calcium-induced phosphorylation of proteins thought to influence synaptic vesicle function, such as MARCKS, synapsin, and SNAP-25, were all reduced in synaptosomes from these transgenic mice. Concomitant with these studies, we searched for new functions of Ral by detecting proteins that specifically bind to it in cells. Consistent with the phenotype of the transgenic mice described above, we found that active but not inactive RalA binds to the Sec6/8 (exocyst) complex, whose yeast counterpart is essential for targeting exocytic vesicles to specific docking sites on the plasma membrane. These findings demonstrate a role for Ral-GTPase signaling in the modulation of the readily releasable pool of synaptic vesicles and suggest the possible involvement of Ral-Sec6/8 (exocyst) binding in modulation of synaptic strength.     

Characterization of the genetic element coding for lactose metabolism in Lactococcus lactis subsp. lactis KP3

The Lactococcus lactis subsp. lactis KP3 Lac genetic element was investigated. KP3 is a lactose-positive (Lac+) transconjugant which contains no detectable plasmid DNA. The KP3 Lac genetic element was self-transmissible (Tra+) and encoded a reduced bacteriophage sensitivity (Rbs+) phenotype. Matings of KP3 with a recombination-deficient (Rec-) recipient resulted in Lac+ transconjugants which were phenotypically indistinguishable from KP3 and contained a 96-MDa plasmid (pJS96). Phenotypic and physical analyses of pJS96 indicated that it was a deletion derivative of a putative pKB32::pJS88 Lac+ Tra+ cointegrate. pKB32 is the Lac plasmid and pJS88 is the Tra+ Rbs+ plasmid in L. lactis subsp. lactis 11007, the donor used in obtaining KP3. The results presented suggest that pJS96 is an episome, since it appeared to replicate both as a plasmid and as an integrated part of the chromosome. Conjugal transfer of chromosomal DNA mediated by pJS96 was not observed. Conjugal transfer of pJS96 resulted in Lac+ transconjugants containing plasmids ranging in size from 21 to 90 MDa. Only in Rec+ recipients were transconjugants isolated which appeared to contain pJS96 integrated into the host chromosome. Restriction analysis of several plasmids in the 21 to 90 MDa range suggested the deletions were due to intramolecular transposition of a transposable element on pJS96. This report suggests that a self-transmissible episome exists in KP3 and provides an explanation of how plasmids which vary in size yet encode similar phenotypes may be formed and disseminated.     

Biosynthesis of marine natural products: isolation and characterization of a myrcene synthase from cultured tissues of the marine red alga Ochtodes secundiramea

The acyclic monoterpene myrcene is the likely progenitor of the unusual cytotoxic halogenated monoterpenes that are found in marine algae and that function as feeding deterrents to herbivores. Myrcene synthase was isolated from suspension cultures of the marine red alga Ochtodes secundiramea, representing the first enzyme of this type from a marine organism. The algal myrcene synthase produces exclusively myrcene from the natural substrate geranyl diphosphate (GDP), utilizes Mg(+2) as the required divalent metal ion cofactor, has a molecular mass of about 69 kDa, and exhibits a pH optimum near 7.2. These features are similar to those of monoterpene synthases from terrestrial organisms. When incubated with neryl diphosphate (the cis-isomer of GDP), the O. secundiramea myrcene synthase produces the cyclic monoterpene limonene, whereas incubation with (+/-)linalyl diphosphate (the tertiary allylic isomer of geranyl diphosphate) yields both acyclic and cyclic monoterpenes. These results suggest that the enzyme is incapable of isomerizing geranyl diphosphate to linalyl diphosphate, a feature common to all monoterpene cyclases from terrestrial sources. The limited catalytic capability of the myrcene synthase may reflect the ancient evolutionary origin of the producing organism. The ability to assay this enzyme in cultured algae, grown under strictly defined conditions, provides an unparalleled opportunity to delineate factors eliciting the biosynthesis of this class of secondary metabolites, to investigate the metabolic pathway leading to the halogenated monoterpenes, and to determine their role in the chemical ecology of marine algae.