Self-assembled monolayers: solidification of carbamazepine in Form II at an interface

A self-assembled monolayer incorporating well-spaced biphenyl moieties initiates solidification of carbamazepine at its interface. A detailed analysis of the resulting crystals using X-ray powder diffraction, FTIR-ATR as well as thermomicroscopy, indicates a preference for its crystallization in trigonal (Form II) polymorph.     

Simplicity of C*-algebras associated to higher-rank graphs

We prove that if is a row-finite k-graph with no sources, thenthe associated C*-algebra is simple if and only if is cofinaland satisfies Kumjian and Pask's aperiodicity condition, knownas Condition (A). We prove that the aperiodicity condition isequivalent to a suitably modified version of Robertson and Steger'soriginal nonperiodicity condition (H3), which in particularinvolves only finite paths. We also characterise both cofinalityand aperiodicity of in terms of ideals in C*().     

Quantifying interactions between cell receptors and adhesion ligand-modified polymers in solution

Specific interactions between cells and cell-interactive polymers in solution were investigated by the fluorescence resonance energy transfer (FRET) technique and rheological measurements. The green fluorescence emission was dramatically reduced when rhodamine-stained cells were mixed with a fluorescein-labeled RGD-alginate solution, compared with those mixed with no RGD-containing alginate solution, which indicated an occurrence of FRET and existence of specific interactions between the cells and the polymers in solution. Rheological measurements also confirmed the formation of ordered structures of cell/polymer mixtures, caused by specific cell-polymer interactions. The FRET method was able to provide a useful means of investigating cell-polymer interactions, both in a qualitative and quantitative manner, and this approach to monitoring and controlling specific interactions between cells and polymers could be useful in the design and tailoring of polymeric carriers for cells, as well as for biological drugs, especially for tissue engineering applications.     

Photochemical generation of aziridinium imides: are Als bystanders or perpetrators in the ene reaction?

A non-equilibrating mixture of two aziridinium imides (AIs) resulting from the photoaddition of N-methyl-1,2,4-triazoline-3,5-dione and cycloheptene has been prepared. Warming the AIs produces only the product of the expected ene reaction with no back-reaction to starting materials. Even though one of the pair does not have the geometry necessary for hydrogen abstraction, both AIs disappear at essentially the same rate, showing that AIs cannot be the direct precursors of the ene product.     

Diffusion within ultrathin, dense nanoporous silica films

In this work the origin of permselectivity in dense silica films which possess a pore structure with pore sizes commensurate with the molecular size of the diffusing gas species is investigated. Much of the recently reported work in this field has involved the development of composite membrane films, and while it is generally assumed that the transport process of the gas species within the selective layer of these films is activated in nature, there are anomalies with this simplified picture. In this paper a new model is developed which, for the first time, explains the permselective behavior of the thin selective coatings ubiquitous to membrane separation processes. The model involves the existence of two primary transport domains within the solid film, one of which rapidly conducts the permeating gas (under non-Fickian conditions), while the second domain involves a slow diffusion mode characterized by normal Fickian transport. To validate the model, molecular dynamics simulations are conducted for diffusion of a number of simple gases (He, N(2), and CO(2)) within silica glasses over a range of solid densities. The silica media employed in these studies are based on a novel approach developed in this work for the construction of three-dimensionally periodic atomistic structures of silica of arbitrary density in which network bond connectivity is ensured. The results obtained from this work are in qualitative agreement with experimental observations and confirm the existence of dual mode transport which is central to the interpretation of the permselectivity in composite membranes systems.     

Rapid identification, by use of the LTQ Orbitrap hybrid FT mass spectrometer, of antifungal compounds produced by lactic acid bacteria

Fungal contamination of food causes health and economic concerns. Several species of lactic acid bacteria (LAB) have antifungal activity which may inhibit food spoilage fungi. LAB have GRAS (generally recognised as safe) status, allowing them to be safely integrated into food systems as natural food preservatives. A method is described herein that enables rapid screening of LAB cultures for 25 known antifungal compounds associated with LAB. This is the first chromatographic method developed which enables the rapid identification of a wide range of antifungal compounds by a single method with a short analysis time (23 min). Chromatographic separation was achieved on a Phenomenex Gemini C18 100A column (150 mm?×?2.0 mm; 5 μm) by use of a mobile-phase gradient prepared from (A) water containing acetic acid (0.1%) and (B) acetonitrile containing acetic acid (0.1%), at a flow rate of 0.3 µL min^?1. The gradient involved a progressive ramp from 10–95% acetonitrile over 13 min. The LC was coupled to a hybrid LTQ Orbitrap XL fourier-transform mass spectrometer (FTMS) operated in negative ionisation mode. High mass accuracy data (<3 ppm) obtained by use of high resolution (30,000 K) enabled unequivocal identification of the target compounds. This method allows comprehensive profiling and comparison of different LAB strains and is also capable of the identification of additional compounds produced by these bacteria.     

Evaluation of a polymerase chain reaction-based heteroduplex assay for detecting the adulteration of processed orange juice with mandarin juice

A polymerase chain reaction (PCR)-based heteroduplex assay was evaluated for the detection of mandarin juice in processed orange juice. PCR amplification of a fragment of the chloroplast trnT-trnL intergenic spacer derived from mixtures of DNA extracted from orange and mandarin juice resulted in heteroduplex formation. The heteroduplex resulted from the co-amplification of a fragment containing an 8 base-pair indel that distinguished mixtures of orange and mandarin juice from orange juice and mandarin juice alone. The heteroduplex assay was evaluated against authentic juices obtained from different citrus species and confirmed that the marker was homogeneous within Citrus. The data obtained demonstrated maternal inheritance of chloroplast type in Citrus sp. and allowed the identification and confirmation of the maternal parentage of unknown and known citrus hybrids. Analysis of the quantitative potential of the PCR and polyacrylamide gel electrophoresis (PAGE) analysis demonstrated good repeatability with a coefficient of variation of 7.5%. Greatest sources of variance in experimental results were attributable to species and varietal differences in the levels of the PCR target. Mandarin juice contained approximately 18% (w/v) less PCR target sequence than did orange juice. The assay was tested in a blind trial using processed juices and correctly identified 20/22 samples with no false-positive results.     

Alginate hydrogels as biomaterials

[Image: see text] Alginate hydrogels are proving to have a wide applicability as biomaterials. They have been used as scaffolds for tissue engineering, as delivery vehicles for drugs, and as model extracellular matrices for basic biological studies. These applications require tight control of a number of material properties including mechanical stiffness, swelling, degradation, cell attachment, and binding or release of bioactive molecules. Control over these properties can be achieved by chemical or physical modifications of the polysaccharide itself or the gels formed from alginate. The utility of these modified alginate gels as biomaterials has been demonstrated in a number of in vitro and in vivo studies.Micro-CT images of bone-like constructs that result from transplantation of osteoblasts on gels that degrade over a time frame of several months leading to improved bone formation.