Total Syntheses of (−)-Spirooliganones A and B

The enantioselective syntheses of (−)-spirooliganones A and B have been accomplished in eight steps from commercially available starting materials. Noteworthy transformations include a three-component hetero-Diels–Alder cycloaddition to construct the tetracyclic core of spirooliganones, a Sharpless asymmetric dihydroxylation, and a tandem oxidative dearomatization/cyclization to build the oxa-spiro cyclohexadienone skeleton. The straightforward syntheses were performed without protecting groups

Surface Coassembly of Polymer Brushes and Polymer–Protein Bioconjugates: An Efficient Approach to the Purification of Bioconjugates under Mild Conditions

Well-defined polymer–protein bioconjugates are widely used in therapeutics and biocatalysis. One of the challenges in the synthesis of bioconjugates is the efficient separation of the target conjugate molecules from reaction systems. In this research, surface coassembly of polymer brushes and polymer–protein bioconjugates is investigated, and it is demonstrated that the coassembly approach can be applied in the purification of polymer–protein bioconjugates. Bovine serum albumin-poly­(N-isopropylacrylamide) (BSA-PNIPAM) bioconjugates were synthesized by the “grafting from” approach, and PNIPAM brushes on silica particles were prepared by the “grafting to” approach. PNIPAM brushes on silica particles are able to coassemble with BSA-PNIPAM at a temperature above the lower critical solution temperature of PNIPAM. Two-layer surface structures with collapsed PNIPAM in the inner layers and BSA in the outer layers are formed on the silica particles. The size of the silica particles and molecular weight of PNIPAM on the bioconjugates exert influences on the coassembly. The coassembly approach can be used in the purification of bioconjugates. After repeated coassembly centrifugation-release cycles, all the BSA-PNIPAM bioconjugates can be removed from the reaction solutions, and the purified bioconjugates are obtained

Peer-regarding fairness in supply chain

<p>People exhibit peer-regarding fairness concern when others who are in similar circumstances are treated unfairly. The fairness concern derives from a sense of sympathy or schadenfreude. We study it in a distribution channel where a supplier deals with two retailers located at independent markets. Sympathy means the decrease of the retailer’s utility because he believes that his peer’s unfair treatment is undeserved, while schadenfreude indicates the utility increase as the unfair treatment is perceived deserved. The two retailers are offered wholesale prices sequentially and set their retail prices if they accept the offers. In our paper, the second retailer has the peer-regarding fairness concern. We show the following in regards to this idea: (i) the retailers’ profits and the distribution channel performance can be improved by the peer-regarding fairness concern for sympathy; (ii) the retailers’ profits and the channel performance can be reduced by the peer-regarding fairness concern for schadenfreude; and (iii) the peer-regarding fairness concern for sympathy is unfavourable to the supplier, and the second retailer may be punished separately if the concern is not strong enough, while the supplier benefits from the peer-regarding fairness concern for schadenfreude and may exploit the second retailer solely if the schadenfreude parameter is large.</p

Total Synthesis of (±)-Przewalskin B

A concise total synthesis of przewalskin B was accomplished from readily available diene 7. Key features of the synthesis involved a Diels–Alder reaction to install the A ring, a Claisen–Johnson rearrangement to establish the spiro-quaternary center, and a ring-closing metathesis (RCM) of a sterically crowded system to construct the cyclic enone moiety

Single Molecule Biosensing Using Color Coded Plasmon Resonant Metal Nanoparticles

Plasmonic metal nanoparticles (NPs) exhibit size, shape, and composition-dependent optical properties and have been studied extensively in the field of biosensing, but wide applications so far are limited by a lack of both highly sensitive and quantitative yet cost-effective optical detection schemes. We present a single molecule biosensing method based on color differentiation of scattered light between single plasmonic NPs and DNA hybridization-induced NP aggregates. With a seed-mediated NP growth method and a fast DNA modification method, highly stable, spectrally uniform and monodisperse Au NP (40 nm) and Au/Ag/Au composite NP (33 nm) probes were successfully prepared. Through theoretical calculations, single NP spectral measurements, and real time single-NP tracking experiments, we show that binding of a single target molecule between two NP probes can be recognized without separation from the unbound NPs by simply using a darkfield microscope equipped with a conventional light source and a color charge coupled device (CCD) camera. The detection limit of this homogeneous assay reached 0.02 pM. As an initial demonstration of multiplexed sensing at the single NP level, we used Au NPs and Au/Ag/Au composite NPs as different color probes. This scheme could be potentially applied to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies

Effect of RABEX-5 on the growth of SGC-7901 cells <i>in vivo</i>.

<p>(A) Tumor volumes were measured at different time points in mice inoculated with SGC-7901 cells infected with RABEX-5 knockdown lentiviral vector (SGC-7901/KD cells). (B) Tumors harvested from mice 4 weeks post-injection with SGC-7901/KD cells (C) Individual tumor volumes for each mouse after dissection. (D) The final tumor weight was measured at the end of the experiment. (E) Expression of <i>VEGF</i> mRNA in tumors derived from nude mice. (F) Immunohistochemical analysis of VEGF expression in tumors derived from SGC-7901/NC and SGC-7901/KD groups. *<i>P</i><0.05; **<i>P</i><0.01.</p

<b>Shining at the Tips: Anisotropic Deposition of Pt Nanoparticles Boosting Hot Carrier Utilization for Plasmon-Driven Photocatalysis</b>

Bimetallic nanostructures are a promising candidate for plasmon-driven photocatalysis. However, knowledge on the generation and utilization of hot carriers in bimetallic nanostructures is still limited. In this work, we explored Pt position-dependent photocatalytic properties of bimetallic Au nanobipyramids (Au NBPs) with single-molecule fluorescence imaging. Compared with all-deposited core–shell nanostructures (aPt-Au NBPs), single-molecule imaging and simulation results show that the end-deposited bimetallic nanostructures (ePt-Au NBPs) can maintain a strong electromagnetic (EM) field and further promote the generation and transfer of energetic hot electrons for photocatalysis. Even though the Pt lattice is more stable than Au, the strong EM field at the sharp tips can boost lattice vibration, where enhanced spontaneous surface restructuring for active reaction site generation takes place. Significantly enhanced catalytic efficiency from ePt-Au NBPs is observed in contrast to that of Au NBPs and aPt-Au NBPs. These microscopic evidences offer valuable guidelines to design plasmon-based photocatalysts, particularly for bimetallic nanostructures

Velocity distribution of Valve A at (a) <i>φ</i> = -120° section and (b) <i>φ</i> = 120° section.

<p><i>φ</i> is the angle from <i>x</i> axis. <i>φ</i> = -120° and <i>φ</i> = 120° are symmetric about <i>y</i> =0 plane. At different <i>z</i> there is a big velocity peak which becomes flat with <i>z</i> decreases.</p

Downregulation of RABEX-5 in SGC-7901 and NCI-N87 cells and effects on cell proliferation and colony formation.

<p>(A) Western blot analysis of RABEX-5 protein expression in seven gastric cancer cell lines and GES-1. (B) RABEX-5 protein levels in SGC-7901/KD, SGC-7901/NC, NCI-N87/KD and NCI-N87/NC cells were analyzed by western blot. (C) CCK-8 cell proliferation assay for SGC-7901/KD, NCI-N87/KD and control groups. Curves indicate a significant level of proliferation compared with controls (<i>P</i><0.05). (D) Representative images and quantification of colony formation assays in each cell line. *<i>P</i><0.05; **<i>P</i><0.01.</p