Cation deficiency associated with the chemical exfoliation of lithium cobalt oxide

Compositional changes associated with the chemical exfoliation of lithium cobalt oxide, a layered transition metal oxide, are discussed. Starting from a layered bulk structure, lithium cobalt oxide can undergo chemical exfoliation through a two-step method: treatment with a protic acid, then treatment with tetramethylammonium hydroxide (this intercalates the layered structure and yields exfoliated nanosheets). This work provides an in-depth analysis of compositional and structural changes occurring to the powder upon the first step to exfoliation, treatment with acid, revealing variations in vacancies and valence changes depending on the conditions used. Through coupled analysis of X-ray photoelectron spectroscopy, X-ray diffraction, UV-Vis absorption spectroscopy, and inductively coupled plasma-optical emission spectroscopy data, we illustrate that both lithium and cobalt ions are diffusing out the structure along with the dissolution of full unit cells. As such, nanosheets accessed from the bulk by this exfoliation process should not be considered simply as divisions of the original unit cell. This work provides fundamental insights on the stability of LiCoO₂ and the exfoliation of layered transition metal oxides, beyond the access of individual nanosheets, and is vital to determining structure-property relationships of chemically exfoliated nanosheets (eg, changes in valency which dictate catalytic activity, magnetic susceptibility, etc).     

Bioactive Alkaloids from Plants Poisonous to Livestock in North America

Plants produce a multiplicity of chemical compounds which have a variety of uses including flavors, fragrances, insecticides, dyes, poisons, and pharmaceutical agents. In this review, we focus on plant alkaloids from the genera Delphinium, Lupinus, Conium, Nicotiana, Veratrum, and selected plant endophyte derived alkaloids. Alkaloids discussed include norditerpenoid alkaloids which act as antagonists to block the ligand binding sites of nicotinic acetylcholine receptors and cause acute toxicosis in adult animals which can result in death. The inhibition of fetal movement and resulting fetal defects caused by quinolizidine and piperidine alkaloids, the inhibition of the hedgehog (Hh) signaling pathway by Veratrum alkaloids, and compounds derived from fungal endophytes that form symbioses with plant hosts will be also be discussed. The bioactivity of these alkaloids makes them useful tools for research and in human and veterinary medicine or potentially harmful toxins.     

Remote sensing for detection and monitoring of vegetation affected by oil spills

This study is aimed at demonstrating the application of vegetation spectral techniques for detection and monitoring of the impact of oil spills on vegetation. Vegetation spectral reflectance from Landsat 8 data were used in the calculation of five vegetation indices (normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), adjusted resistant vegetation index 2 (ARVI2), green-infrared index (G-NIR) and green-shortwave infrared (G-SWIR) from the spill sites (SS) and non-spill sites (NSS) in 2013 (pre-oil spill), 2014 (oil spill date) and 2015 (post-oil spill) for statistical comparison. The result shows that NDVI, SAVI, ARVI2, G-NIR and G-SWIR indicated a certain level of significant difference between vegetation condition at the SS and the NSS in December 2013. In December 2014 vegetation conditions indicated higher level of significant difference between the vegetation at the SS and NSS as follows where NDVI, SAVI and ARVI2 with p-value 0.005, G-NIR – p-value 0.01 and G-SWIR p-value 0.05. Similarly, in January 2015 a very significant difference with p-value <0.005. Three indices NDVI, ARVI2 and G-NIR indicated highly significant difference in vegetation conditions with p-value <0.005 between December 2013 and December 2014 at the same sites. Post-spill analysis shows that NDVI and ARVI2 indicated low level of significance difference p-value <0.05 suggesting subtle change in vegetation conditions between December 2014 and January 2015. This technique may help with the real time detection, response and monitoring of oil spills from pipelines for mitigation of pollution at the affected sites in mangrove forests.     

Engineering Next Generation Cyclized Peptide Ligands for Light-Controlled Capture and Release of Therapeutic Proteins

Photo-affinity adsorbents (i.e., translucent matrices functionalized with ligands featuring light-controlled biorecognition) represent a futuristic technology for purifying labile biologics. In this study, a framework for prototyping photo-affinity adsorbents comprising azobenzene-cyclized peptides (ACPs) conjugated to translucent porous beads (ChemMatrix) is presented. This approach combines computational and experimental tools for designing ACPs and investigating their light-controlled isomerization kinetics and protein biorecognition. First, a modular design for tailoring ACP's conformation, facilitating sequencing, and streamlining the in silico modeling of cis/trans isomers and their differential protein binding is introduced. Then, a spectroscopic system for measuring the photo-isomerization kinetics of ACPs on ChemMatrix beads is reported; using this device, it is demonstrated that the isomerization at different light intensities is correlated to the cyclization geometry, specifically the energy difference of trans versus cis isomers as calculated in silico. Also, a microfluidic device for sorting ACP-ChemMatrix beads to select and validate photo-affinity ligands using Vascular Cell Adhesion Molecule 1 (VCAM-1) as target protein and cyclo_AZOB[GVHAKQHRN-K*]-G-ChemMatrix as model photo-affinity adsorbent is presented. The proposed ACPs exhibit rapid and defined light-controlled isomerization and biorecognition. Controlling the adsorption and release of VCAM-1 using light demonstrates the potential of photo-affinity adsorbents for targets whose biochemical liability poses challenges to its purification.     

Chemoproteomic Profiling of Covalent XPO1 Inhibitors to Assess Target Engagement and Selectivity

Selinexor, a covalent XPO1 inhibitor, is approved in the USA in combination with dexamethasone for penta-refractory multiple myeloma. Additional XPO1 covalent inhibitors are currently in clinical trials for multiple diseases including hematologic malignancies, solid tumor malignancies, glioblastoma multiforme (GBM), and amyotrophic lateral sclerosis (ALS). It is important to measure the target engagement and selectivity of covalent inhibitors to understand the degree of engagement needed for efficacy, while avoiding both mechanism-based and off-target toxicity. Herein, we report clickable probes based on the XPO1 inhibitors selinexor and eltanexor for the labeling of XPO1 in live cells to assess target engagement and selectivity. We used mass spectrometry-based chemoproteomic workflows to profile the proteome-wide selectivity of selinexor and eltanexor and show that they are highly selective for XPO1. Thermal profiling analysis of selinexor further offers an orthogonal approach to measure XPO1 engagement in live cells. We believe these probes and assays will serve as useful tools to further interrogate the biology of XPO1 and its inhibition in cellular and in vivo systems.     

Pricing and warranty decisions in a two-period closed-loop supply chain

For a two-period closed-loop supply chain (CLSC) consisting of a manufacturer and a retailer, Stackelberg game analyses are conducted to examine pricing and warranty decisions under two warranty models depending on who offers warranty for new and remanufactured products and the corresponding benchmark models with a warranty for new products only. Next, we identify the conditions under which warranty for remanufactured products is offered and investigate how this warranty affects the CLSC operations. Subsequently, comparative studies are carried out to examine equilibrium decisions, profitability and consumer surplus of the CLSC between the two warranty models. Analytical results show that offering warranty for remanufactured products does not affect new product pricing in period 2, but influences the pricing of new products in period 1 and remanufactured products in period 2, thereby enhancing remanufacturing, individual and channel profitability, and consumer surplus. Compared to the retailer warranty for remanufactured products, the manufacturer warranty can attain a more equitable profit distribution. If the warranty cost advantage of the manufacturer (retailer) is significant relative to that of the retailer (the manufacturer), the manufacturer (retailer) arises as a natural choice to offer warranty for remanufactured products as this decision enhances both profitability and consumer surplus.     

Hydrogen production from methane autothermal reforming over CaTiO3, BaTiO3 and SrTiO3 supported nickel catalysts

Nickel supported on perovskite supports were investigated in the autothermal reforming of methane. The catalysts were prepared by incipient wetness impregnation and characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), N₂ physisorption, H₂ temperature programmed reduction (H₂-TPR), H₂ chemisorption, dehydrogenation of cyclohexane model reaction and Raman spectroscopy. The alumina supported catalyst exhibited highest initial conversion and selectivity to H₂, however it deactivated. All catalysts with perovskite support were very stable, with Ni/CaTiO₃ and Ni/BaTiO₃ converting over 70% of the methane. Due to carbon formation, Ni/SrTiO₃ conversion was only 50%. Turnover frequency was higher on perovskite supported catalysts. Deactivated Ni/Al₂O₃ favored total oxidation of methane instead of methane reforming, however the selectivity of catalysts supported on perovskites remained stable.     

Conjugation of Dasatinib with MHI-148 Has a Significant Advantageous Effect in Viability Assays for Glioblastoma Cells

We hypothesized that conjugation of the near-infrared dye MHI-148 with the anti-leukemia drug dasatinib might produce a potential theranostic for glioblastoma. In fact, the conjugate was found to bind the kinases Src and Lyn, and to inhibit the viability of a glioblastoma cell line with significantly greater potency than dasatinib alone, MHI-148 alone, or a mixture of dasatinib and MHI-148 at the same concentration. It was also used to successfully image a subcutaneous glioblastoma tumor in vivo.     

Effect of A-site substitutions on energy storage properties of BaTiO3-BiScO3 weakly coupled relaxor ferroelectrics

Weakly coupled relaxors based on compositions (1-x) BaTiO₃-xBiMeO₃, where Me is a metal ion, have attracted attention as potential candidates for high-temperature high-energy density capacitors. However, the necessary Bi content is typically high with x = 0.3-0.4. In order to reduce problems associated with compatibility for base metal electrodes and due to additional problems due to Bi volatility, it is desirable to lower the Bi content in the overall composition for these materials. Here, we have explored a possible way to reduce BiMeO₃ content through additional A-site substitutions viz. Ca and Sn. The relaxor nature and energy storage properties of Sn-modified (Ba,Ca)(Ti)O₃-BiScO₃ ceramics were determined from their dielectric and ferroelectric behaviors. The material showed attractive properties in terms of a frequency-independent (200 Hz-1 MHz) dielectric response from room temperature to 200°C, extremely low loss and high-energy storage efficiency. The structural phenomena underlying the functional properties of Sn-modified (Ba,Ca)TiO₃-BiScO₃ are characterized from temperature-dependent X-ray diffraction and pair distribution function analysis. In broader terms, the study illustrates the potential for tailoring relaxor behavior in Pb-free ferroelectrics by combining phenomena, such as quantum fluctuations and lone pair stereochemical effect associated with different solid-solution substitutions.