Essential normality of linear fractional composition operators in the unit ball of ℂ<Superscript><Emphasis Type="Italic">N</Emphasis></Superscript>

Let φ be a linear fractional self-map of the ball B _N with a boundary fixed point e ₁, we show that

Isolation and Difference in Anti-Staphylococcus aureus Bioactivity of Curvularin Derivates from Fungus Eupenicillium sp.

With the anti-microbial and anti-tumor composite screening model, bioassay-guided fractionation led to the isolation of two structurally related bioactive compounds, curvularin and αβ-dehydrocurvularin, from ethyl acetate extract of Eupenicillium sp. associated with marine sponge Axinella sp. Further study on the structure–activity relationship demonstrated that both compounds exhibited differences in bioactive profiles which are highly associated with their minor structural differences. Both curvularin and αβ-dehydrocurvularin have similar level of anti-fungal and anti-tumorous activity, while αβ-dehydrocurvularin is active against Staphylococcus aureus with a minimal inhibitory concentration of 375 μg/ml but curvularin does not. No detectable activity against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa exists for both compounds. It is suggested that the partial planar backbone structure, due to the conjugation of π electrons in the presence of a 3,4-double bond and the carbonyl group at position C-2 in αβ-dehydrocurvularin, acts as a key factor for the inhibition of S. aureus, a Gram-positive low G + C bacteria that are often the hospital-acquired and/or community-acquired pathogen.     

An image encryption scheme combining chaos with cycle operation for DNA sequences

An image encryption scheme is proposed using high-dimensional chaotic systems and cycle operation for DNA sequences. In the scheme, the pixels of the original image are encoded randomly with the DNA coding rule controlled by a key stream produced from Chen’s hyper-chaos. In addition to confusion on the DNA sequence matrix with Lorenz system, a cycle operation for DNA sequences is projected to diffuse the pixel values of the image. In order to enhance the diffusion effect, a bitwise exclusive-OR operation is carried out for the decoded matrices with a binary key stream, and then the cipher-image is obtained. Simulation results demonstrate that the proposed image encryption scheme with acceptable robustness is secure against exhaustive attack, statistical attack and differential attack.     

An arithmetic-geometric mean inequality approach for determining the optimal production lot size with backlogging and imperfect rework process

Some classical studies on economic production quantity (EPQ) models with imperfect production processes have focused on determining the optimal production lot size. However, these models neglect the fact that the total production-inventory costs can be reduced by reworking imperfect items for a relatively small repair and holding cost. To account for the above phenomenon, we take the out of stock and rework into account and establish an EPQ model with imperfect production processes, failure in repair and complete backlogging. Furthermore, we assume that the holding cost of imperfect items is distinguished from that of perfect ones, as well as, the costs of repair, disposal, and shortage are all included in the proposed model. In addition, without taking complex differential calculus to determine the optimal production lot size and backorder level, we employ an arithmetic-geometric mean inequality method to determine the optimal solutions. Finally, numerical examples and sensitivity analysis are analyzed to illustrate the validity of the proposed model. Some managerial insights are obtained from the numerical examples.     

ChemInform Abstract: Prediction and Characterization of the HMgH···LiX (X: H,OH, F,CCH, CN,and NC) Complexes: A Lithium—Hydride Lithium Bond

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

A new method for microcapsule characterization: use of fluorogenic genipin to characterize polymeric microcapsule membranes

Numerous microcapsule systems have been developed for a wide range of applications, including the sustained release of drugs, cell transplantation for therapy, cell immobilization, and other biotechnological applications. Despite the fact that microcapsule membrane is a dominant factor governing overall microcapsule performance, its characterization is challenging. We report a new method for characterizing microcapsule membranes, using the most common alginate-poly-L-lysine-alginate (APA) microcapsule as an example. Our data demonstrate that genipin, a naturally derived reagent extracted from gardenia fruits, interacts with poly-L-lysine (PLL) and generates fluorescence. This fluorescence allows clear visualization and easy analysis of the PLL membrane in the APA microcapsules using confocal laser scanning microscopy. The results also show that PLL binding correlates to the reaction variables during PLL coating such as PLL concentration and coating time. In addition, five other different microcapsule formulations consisting of PLL and/or chitosan membranes were examined, and the results imply that this method can be extended to characterize a variety of microcapsule membranes. These findings suggest that genipin can serve as a fluorogenic marker for rapid characterization of microcapsule membranes, a superior method that would have important implications for microcapsule research and potential in many other applications.     

The Synthesis of Chitosan Decorated Reduced Graphene Oxide‐Ferrocene Nanocomposite and its Application in Electrochemical Detection Rhodamine B

Chitosan (CS) decorated reduced graphene oxide‐Ferrocene nanocomposite (RGO?Fc?CS) was synthesized by a one‐pot reaction. In the synthesis process of RGO?Fc?CS, GO?Fc was successfully self‐assembled via the π–π interaction, which had the features of large surface area and the high load. Then GO‐Fc and CS linked via one‐pot under alkaline conditions. The FT?IR, TGA, SEM were employed to characterize the successful synthesis of RGO?Fc?CS composites. A miniature electrochemical system was fabricated by RGO?Fc?CS modified glassy carbon electrode (expressed as RGO?Fc?CS/GCE) for the sensitive detection of RhB enantiomers via DPV. Electrochemical results revealed that the RGO?Fc?CS/GCE exhibited high molecular recognition toward RhB. Due to the synergy between the RGO?Fc and CS, the RGO?Fc?CS/GCE showed a linear range of 0.001–70 μM with a LOD of 0.5 nM, indicating that RGO?Fc?CS/GCE has broad application prospects to simplify monitor RhB real‐time.     

Emerging Two-Dimensional Nanomaterials for Cancer Therapy

Two-dimensional (2D) nanomaterials have drawn tremendous attention due to their unique physicochemical properties and promising applications in the fields of electronics, energy storage, and catalysis. Recently, the biomedicine community has gradually started to recognize the great potential of these nanostructured materials for biomedical applications – in particular those related to cancer therapy. In this review, we provide a brief overview of a few representative 2D nanomaterials, discuss their preparation strategies and physicochemical properties, and highlight their applications in cancer nanomedicine. We expect that this review will shed some light on the new opportunities associated with 2D nanomaterials for biomedical research.     

Auto‐Tandem Cooperative Catalysis Using Phosphine/Palladium: Reaction of Morita–Baylis–Hillman Carbonates and Allylic Alcohols

Auto‐tandem catalysis (ATC), in which a single catalyst promotes two or more mechanistically different reactions in a cascade pattern, provides a powerful strategy to prepare complex products from simple starting materials. Reported here is an unprecedented auto‐tandem cooperative catalysis (ATCC) for Morita–Baylis–Hillman carbonates from isatins and allylic carbonates using a simple Pd(PPh₃)₄ precursor. Dissociated phosphine generates phosphorus ylides and the Pd leads to π‐allylpalladium complexes, and they undergo a γ‐regioselective allylic–allylic alkylation reaction. Importantly, a cascade intramolecular Heck‐type coupling proceeds to finally furnish spirooxindoles incorporating a 4‐methylene‐2‐cyclopentene motif. Experimental results indicate that both Pd and phosphine play crucial roles in the catalytic Heck reaction. In addition, the asymmetric versions with either a chiral phosphine or chiral auxiliary are explored, and moderate results are obtained.