On the Elusive Crystallography of Lithium-Rich Layered Oxides: Novel Structural Models

Lithium-rich layered oxides (LRLOs) are one of the most attractive families among future positive electrode materials for the so-called fourth generation of lithium-ion batteries (LIBs). Their electrochemical performance is enabled by the unique ambiguous crystal structure that is still not well understood despite decades of research. In the literature, a clear structural model able to describe their crystallographic features is missing thereby hindering a clear rationalization of the interplay between synthesis, structure, and functional properties. Here, the structure of a specific LRLO, Li1.28 Mn0.54 Ni0.13 Co0.02 Al0.03 O2 , using synchrotron X-ray diffraction (XRD), neutron diffraction (ND), and High-Resolution Transmission Electron Microscopy (HR-TEM), is analyzed. A systematic approach is applied to model diffraction patterns of Li1.28 Mn0.54 Ni0.13 Co0.02 Al0.03 O2 by using the Rietveld refinement method considering the R3 ¯ $\bar{3}$ m and C2/m unit cells as the prototype structures. Here, the relative ability of a variety of structural models is compared to match the experimental diffraction pattern evaluating the impact of defects and supercells derived from the R3 ¯ $\bar{3}$ m structure. To summarize, two possible models able to reconcile the description of experimental data are proposed here for the structure of Li1.28 Mn0.54 Ni0.13 Co0.02 Al0.03 O2 : namely a monoclinic C2/m defective lattice (prototype Li2 MnO3 ) and a monoclinic defective supercell derived from the rhombohedral R3 ¯ $\bar{3}$ m unit cell (prototype LiCoO2 ).

Cellulose Nanocrystals as Additives in Electrospun Biocompatible Separators for Aprotic Lithium-Ion Batteries

This work concerns the study of electrospun scaffolds as separators for aprotic lithium-ion batteries (LIBs) composed of the amorphous poly-d,l-lactide (PDLLA), in solution concentrations of 8, 10, and 12 wt % and in different ratios with cellulose nanocrystals (CNCs). PDLLA has been studied for the first time as a separator, taking into account its amorphous character that could facilitate electrolyte incorporation into the polymer matrix and influence ionic conductivity, together with CNCs, for reducing the hydrophobicity of the scaffolds. The embedding of the nanocrystals in the scaffolds was confirmed by X-ray diffraction analysis and attenuated total reflectance Fourier transform infrared spectroscopy. The polymer combination influenced the nanofibrous morphology as evaluated by scanning electron microscopy and modulated the electrochemical behavior of the membranes that was investigated through linear sweep voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy tests. Among the studied categories, the P12 series displayed a nonhomogeneous electrolyte resistance and electrochemical stability, differently from P10, whose results suggested their application in LIBs with standard formulation, as confirmed by a preliminary performance test of the P10N6 formulation in a full Li-ion cell configuration.

Pushing Stoichiometries of Lithium-Rich Layered Oxides Beyond Their Limits

Lithium-rich layered oxides (LRLOs) are opening unexplored frontiers for high-capacity/high-voltage positive electrodes in Li-ion batteries (LIBs) to meet the challenges of green and safe transportation as well as cheap and sustainable stationary energy storage from renewable sources. LRLOs exploit the extra lithiation provided by the Li_1.2TM_0.8O₂ stoichiometries (TM = a blend of transition metals with a moderate cobalt content) achievable by a layered structure to disclose specific capacities beyond 200-250 mA h g^-1 and working potentials in the 3.4-3.8 V range versus Li. Here, we demonstrate an innovative paradigm to extend the LRLO concept. We have balanced the substitution of cobalt in the transition-metal layer of the lattice with aluminum and lithium, pushing the composition of LRLO to unexplored stoichiometries, that is, Li_1.2+x (Mn,Ni,Co,Al)_0.8-x O_2-δ. The fine tuning of the composition of the metal blend results in an optimized layered material, that is, Li_1.28Mn_0.54Ni_0.13Co_0.02Al_0.03O_2-δ, with outstanding electrochemical performance in full LIBs, improved environmental benignity, and reduced manufacturing costs compared to the state-of-the-art.

C-reactive protein and coronary composition in patients with percutaneous revascularization

BACKGROUND

C-Reactive Protein (CRP) is considered a predictive factor for cardiovascular events and its serum levels have been shown to correlate with thin cap coronary plaques in sudden coronary death. Whether serum CRP levels are associated with in vivo atherothrombotic features is unclear. We thus analysed samples from coronary atherectomy specimens obtained during percutaneous coronary intervention.

MATERIALS AND METHODS

Patients with coronary artery disease undergoing directional atherectomy, distinguished by unstable versus stable coronary syndrome diagnosis, provided coronary specimens from culprit lesions. Assessment was conducted by means of conventional histology, morphometry and immunohistochemistry. Specific antibodies against erythrocyte-specific protein glycophorin A, endothelial and macrophage antigens were also used.

RESULTS

There were 51 patients with unstable coronary disease and 47 patients with stable angina. Serum CRP levels >/= 1 mg L(-1) were detected in 24/98 patients, and were significantly associated with hypercellularity, macrophage infiltrates, neoangiogenesis and intraplaque haemorrhage (all P < 0.05). Furthermore, coronary plaques from patients with unstable angina contained larger atheromas, more hypercellular plaques, with abundant macrophages, neoangiogenesis and intraplaque haemorrhages and lesser fibrous tissue (all P < 0.05).

CONCLUSIONS

We observed a positive correlation between increased serum CRP levels and typical pathological features of complex atherothrombotic coronary disease, confirming in vivo the mechanistic role of CRP in coronary atherothrombosis.

Using synthetic oligonucleotides as probes

The protocols in this unit describe procedures for using mixtures of 32P-labeled oligonucleotides to screen recombinant DNA clones bound to nitrocellulose filters. A partial amino acid sequence of a protein is used to predict the nucleotide sequence of the gene that would encode it. A mixture of oligonucleotides is chosen that includes all possible nucleotide sequences encoding that amino acid sequence. This mixture of oligonucleotides is then used to screen a recombinant DNA library for the corresponding clones. In some cases however, the exact nucleotide sequence of a desired clone is known and it is possible to use a unique oligonucleotide as a probe.

Oral Manifestations of Langerhans Cell Histiocytosis in a Pediatric Population

Langerhans Cell Histiocytosis is a rare and protean disease of unknown etiology, clinically characterized by single or multiple osteolytic and/or soft tissue lesions. Oral involvement may predate systemic manifestations or mimic infectious/inflammatory disorders. In the present series, oral involvement characterized eight cases of pediatric Langerhans Cell Histiocytosis and oral symptoms represented a very early sign of this disease in four patients. A careful clinical investigation and a proper histologic analysis were required for achieving a definite diagnosis and for confirming clinical suspicion of disease relapse. Immunohistochemistry, that nowadays represents a reliable and accessible ancillary histological technique, allowed the definite diagnosis in all cases of our series.

Preliminary investigations on vitellogenin m-RNA induction in some bioindicator Mediterranean fish species

This paper describes the development of a RT-PCR method for assaying Vtg gene expression in different marine fish as a potentially valuable and sensitive biomarker of exposure to estrogenic chemicals. The levels of Vtg mRNA have been analyzed using primers specifically designed for the various species and the procedures have been standardized relative to actine mRNA expression levels. Different species were analyzed including organisms with a great potential as bioindicators in the Mediterranean (i.e. the red mullet Mullus barbatus, the striped mullet Mugil cephalus, the European eel Anguilla anguilla) or exposed to biomagnification of halogenated hydrocarbons and with elevated commercial value (the bluefin tuna Thunnus thynnus). The analysis of vitellogenin mRNA levels has been standardized in feral fish providing suitable indications for a future development of this approach.

Transmission of Trichosporon asahii oesophagitis by a contaminated endoscope

Two cases of oesophageal trichosporonosis due to a suspected nosocomial infection are reported. Both the patients were immunocompetent and had undergone an endoscopic examination on the same day. Six strains of Trichosporon were isolated: three strains from the oesophageal biopsy of the first patient, one strain from the endoscopic forceps, one from the air in the endoscopy room, and one from the oesophageal biopsy of the second patient. The nosocomial nature of the infection and the role of the endoscopic forceps in transporting the micro-organism was suspected, but the morphology and physiology of the isolated strains did not confirm such hypothesis. To elucidate the nature of the infection and the genetic similarities of the strains isolated, all strains were typed with RFLPs of the rDNA fragment and with RAPD. The results of RAPD using primer (GTG)5 (GACA)4, M13 core sequence, and the 15-mer oligonucleotide GAGGGTGGXGGXTCT indicated the molecular identity of three strains supporting the hypothesis concerning a transport of the aetiological agent from the first patient to the second and that the carrier was the forceps of the endoscopic device.

Bone morphogenetic protein-2 induces cyclin kinase inhibitor p21 and hypophosphorylation of retinoblastoma protein in estradiol-treated MCF-7 human breast cancer cells

The biologic effects and mechanisms by which bone morphogenetic proteins (BMPs) function in breast cancer cells are not well defined. A member of this family of growth and differentiation factors, BMP-2, inhibited both basal and estradiol-induced growth of MCF-7 breast tumor cells in culture. Flow cytometric analysis showed that in the presence of BMP-2, 62% and 45% of estradiol-stimulated MCF-7 cells progressed to S-phase at 24 h and 48 h, respectively. Estradiol mediates growth of human breast cancer cells by stimulating cyclins and cyclin-dependent kinases (CDKs). BMP-2 significantly increased the level of the cyclin kinase inhibitor, p21, which in turn associated with and inactivated cyclin D1. BMP-2 inhibited estradiol-induced cyclin D1-associated kinase activity. Also estradiol-induced CDK2 activity was inhibited by BMP-2. This inhibition of CDK activity resulted in hypophosphorylation of retinoblastoma protein thus keeping it in its active form. These data provide the first evidence by which BMP-2 inhibits estradiol-induced proliferation of human breast cancer cells.

Bone morphogenetic protein-2 blocks MDA MB 231 human breast cancer cell proliferation by inhibiting cyclin-dependent kinase-mediated retinoblastoma protein phosphorylation

Bone morphogenetic protein-2 (BMP-2) has been shown to act as an antiproliferative agent for a number of different cell types. We show that BMP-2 dose-dependently inhibits growth of MDA MB 231 human breast cancer cells. Epidermal growth factor (EGF) stimulates DNA synthesis and entry of these cells into the S-phase. BMP-2 inhibits EGF-induced DNA synthesis by arresting them in G1 phase of the cell cycle. BMP-2 increases the level of cyclin kinase inhibitor p21. Furthermore, we show that exposure of MDA MB 231 cells to BMP-2 stimulates association of p21 with cyclin D1 and with cyclin E resulting in the inhibition of their associated kinase activities. Finally, BMP-2 treatment is found to cause hypophosphorylation of the retinoblastoma protein (pRb), a key regulator of cell cycle progression. Our data provide a mechanism for the antiproliferative effect of BMP-2 in the breast cancer cells.

Bone morphogenetic protein-2 inhibits MAPK-dependent Elk-1 transactivation and DNA synthesis induced by EGF in mesangial cells

Bone morphogenetic protein-2 (BMP-2) is a member of the TGFbeta superfamily of growth and differentiation factors. We investigated the effect of BMP-2 on epidermal growth factor (EGF)-induced mitogenic signaling in kidney glomerular mesangial cells. BMP-2 dose-dependently inhibits EGF-induced DNA synthesis. Maximum effect was obtained at a concentration of 100 ng/ml. BMP-2 had no inhibitory effect on the EGF receptor (EGFR)-associated tyrosine kinase activity indicating that inhibition of DNA synthesis is due to regulation of post-receptor signaling event(s). EGF stimulates MAPK activity in mesangial cells in a time-dependent manner. Inhibition of MAPK by the MEK inhibitor PD098059 blocks EGF-induced DNA synthesis indicating the requirement of this enzyme activity in EGF-mediated mitogenic signaling. Furthermore, we show that exposure of mesangial cells to BMP-2 blocks EGF-induced MAPK activity which leads to phosphorylattion of Elk-1 transcription factor. Using a GAL-4 DNA binding-domain-Elk-1 transactivation domain fusion protein-based reporter assay, we demonstrate that BMP-2 inhibits EGF-induced Elk-1-mediated transcription. These data provide the first evidence that BMP-2 signaling in mesangial cells initiates a negative regulatory cross-talk with MAPK-based transcription to inhibit EGF-induced DNA synthesis.

Interleukin-6 production by human monocytes stimulated with Cryptococcus neoformans components

In order to ascertain if Cryptococcus neoformans components can induce interleukin-6 (IL-6) production, we stimulated human whole blood with purified capsular products. Their potencies in stimulating IL-6 release were mannoproteins > galactoxylomannan = glucuronoxylomannan > alpha(1-3)glucan. IL-6 production was tumor necrosis factor alpha independent and required the presence of monocytes and plasma. Since IL-6 can stimulate replication of the human immunodeficiency virus in monocytic cells, these findings may be clinically relevant.

Purification and molecular cloning of a novel group of BMPs and localization of BMP mRNA in developing bone

Using a novel purification scheme, we have characterized BMP as a 30kD fraction. After reduction, which destroys biological activity, this fraction was shown to be comprised of individual polypeptides with molecular weights of 30kD, 18kD and 16kD. Molecular cloning of these polypeptides resulted in the identification of 4 previously undescribed genes (BMP-1, BMP-2A, BMP-2B, and BMP-3) each of which is capable of directing de novo cartilage formation in vivo. While BMP-1 appears to be unrelated to other known growth factors, the derived amino acid sequence of BMP-2A, 2B, and 3 indicate that they are new members of the TGFb gene family. BMP-1, 2A and 2B are expressed in rat embryos during morphogenesis and can be localized by in situ hybridization to developing limb buds. BMP-3 localizes to neural ectoderm and later on in development to newly forming periosteum. Comparisons to other members of the TGFb family suggest that these newly identified BMPs are involved in pattern formation during early skeletal development.

Recombination in simian virus 40-infected cells. Structure of naturally arising variants ev-2114, ev-2102, and ev-1110

The complete nucleotide sequence has been determined for three newly cloned evolutionary variants from two different independently generated evolutionary series (1100 and 2100 series) of simian virus 40 (SV40). These naturally arising variants, designated ev-1110, ev-2102, and ev-2114, were isolated after five high multiplicity serial passages. The structure of the variants consists of a monomeric unit tandemly repeated four times (ev-2102 and ev-2114) or six times (ev-1110) in the variant genome; the variants have four or six copies, respectively, of the viral origin signal for DNA replication. The DNA content in the three variants is vastly different in that the genome of variant ev-2114 contains only rearranged viral sequences, while variant ev-2102 contains a substitution with monkey DNA sequences consisting of a nearly complete dimeric unit of Alu family sequences as well as less repetitive sequences and variant ev-1110 contains monkey DNA sequences derived solely from repetitive alpha-component DNA. Recombination events, cellular sequences, and structural features of these and other naturally arising SV40 variants are compared.

Naturally arising recombinants that are missing portions of the simian virus 40 regulatory region

When simian virus 40 (SV40) is serially passaged at high multiplicity, a heterogeneous collection of naturally arising variants is generated. Those which are the most abundant presumably have a selective replicative advantage over other defective and wild-type helper SV40s. Two such naturally arising host-substituted variants of SV40 have been characterized in terms of complete nucleotide sequence determination. Evolutionary variant ev-1101 (previously isolated by Lee et al., Virology 66:53-69, 1975) is from undiluted serial passage 13, whereas ev-2101 is newly isolated from undiluted serial passage 6 of an independently-derived evolutionary series. Both variants contain a five-times tandemly repeated segment of DNA consisting of viral Hin C and Hin A sequences that have recombined with a segment of host DNA that is not highly reiterated in the monkey genome. The monkey segment differs in the two variants as does the size of the viral segment retained. In two additional host-substituted variants, ev-1102 (previously isolated from serial passage 20 by Brockman et al., Virology 54:384-397, 1973) and ev-1108 (newly isolated from serial passage 40), the SV40 sequences derived from the replication origin are present as inverted repetitions. The inverted repeat regions of these two variants have been analyzed at the nucleotide sequence level and are compared with SV40 variant ev-1104 from passage 45 (previously characterized by Gutai and Nathans, J. Mol. Biol. 126:259-274, 1978). The viral segment containing the regulatory signals for replication and viral gene expression is considerably shortened in later serial passages as demonstrated by these five variants. It is of interest that the variants presumably arose due to their enhanced replication efficiency, yet are missing some of the sequence elements implicated in the regulation of replication. Furthermore, a comparison of the structure of the replication origin regions indicates that additional changes occur in the SV40 regulatory region with continued undiluted serial passage.