NMR structural characterization from one‐bond 13C?13C couplings: Complete assignment of a hydrogen‐poor depsidone

The connectivity, conformation, tautomeric form, and dynamics of a new depsidone (perisalazinic acid) were characterized using one‐bond ¹³C? ¹³C NMR scalar couplings (¹J_CC) obtained from the INADEQUATE experiment. Characterization of perisalazinic acid using more conventional NMR techniques is problematic due to the extremely limited number of C? H protons present. In the present study, 81 candidate structures were considered and a best fit structure was selected by comparing computed ¹J_CC values for each candidate to 15 experimental values. Of the six flexible moieties in perisalazinic acid, three are adequately represented by a single orientation stabilized by intramolecular hydrogen bonding. The three remaining groups are present as mixtures of conformers with two sites consisting of a pair of conformations and another disordered over six orientations. This study demonstrates the feasibility of complete three‐dimensional structural characterization of an unknown using only theoretical and experimental ¹J_CC values.     

The distinguishing number of quasiprimitive and semiprimitive groups

The distinguishing number of $$G \leqslant \mathrm {Sym}(\Omega )$$ is the smallest size of a partition of $$\Omega $$ such that only the identity of G fixes all the parts of the partition. Extending earlier results of Cameron, Neumann, Saxl, and Seress on the distinguishing number of finite primitive groups, we show that all imprimitive quasiprimitive groups have distinguishing number two, and all non-quasiprimitive semiprimitive groups have distinguishing number two, except for $$\mathrm {GL}(2,3)$$ acting on the eight non-zero vectors of $$\mathbb {F}_3^2$$ , which has distinguishing number three.     

Vibrational spectra of cyclic C8 in solid argon

Vapors from solid and powdered carbon, emitted from an oven cycled between 2000 and 3000 K, were co-condensed with argon onto a CsI substrate maintained at 10 K. The cycling process produced a multilayered matrix with regions of high carbon density alternating with layers of argon. FTIR measurements including ¹³C isotopic data, supported by ab initio calculations, allow the assignment of a band observed at 1817.8 cm⁻¹ to the ν₁₂(e_u) fundamental of cyclic C₈.     

Advances in Platinum Chemotherapeutics

The approved platinum(II)‐based anticancer agents cisplatin, carboplatin and oxaliplatin are widely utilised in the clinic, although with numerous disadvantages. With the aim of circumventing unwanted side‐effects, a great deal of research is being conducted in the areas of cancer‐specific targeting, drug administration and drug delivery. The targeting of platinum complexes to cancerous tissues can be achieved by the attachment of small molecules with biological significance. In addition, the administration of platinum complexes in the form of platinum(IV) allows for intracellular reduction to release the active form of the drug, cisplatin. Drug delivery includes such technologies as liposomes, dendrimers, polymers and nanotubes, with all showing promise for the delivery of platinum compounds. In this paper we highlight some of the recent advances in the field of platinum chemotherapeutics, with a focus on the technologies that attempt to utilise the cytotoxic nature of cisplatin, whilst improving drug targeting to reduce side‐effects.     

Quadruplex DNA‐Stabilising Dinuclear Platinum(II) Terpyridine Complexes with Flexible Linkers

Four dinuclear terpyridineplatinum(II) (Pt–terpy) complexes were investigated for interactions with G‐quadruplex DNA (QDNA) and duplex DNA (dsDNA) by synchrotron radiation circular dichroism (SRCD), fluorescent intercalator displacement (FID) assays and fluorescence resonance energy transfer (FRET) melting studies. Additionally, computational docking studies were undertaken to provide insight into potential binding modes for these complexes. The complexes demonstrated the ability to increase the melting temperature of various QDNA motifs by up to 17 °C and maintain this in up to a 600‐fold excess of dsDNA. This study demonstrates that dinuclear Pt–terpy complexes stabilise QDNA and have a high degree of selectivity for QDNA over dsDNA.     

Population needs assessment and access modelling for cardiac services

The National Service Framework (NSF) for Coronary Heart Disease (CHD), recently published by the Department of Health, specifies Government target rates for different cardiac procedures. This paper describes how the Eastern Regional Office of the Department of Health, with current rates approximately half the NSF target levels, designed a strategy to plan rationally for increases in service provision. A bottom-up needs assessment model was used to predict the population requirements for these CHD procedures and accounts for the effects of demographic change, anticipated reduction in the incidence of heart disease due to primary prevention programmes and the expected improvement in cardiology and cardiac surgery technologies. It is predicted that excess procedures would be required across the region over the next 20 years, and so a geographical access model was developed and used to recommend the building and location of a new tertiary cardiac centre to meet the increased demand. These tools have successfully been used in the Eastern Region to plan long-term increases in CHD rates in order to achieve Department of Health targets.     

Determining Energies and Cross Sections of Individual Ions Using Higher-Order Harmonics in Fourier Transform Charge Detection Mass Spectrometry (FT-CDMS)

A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (>?300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS. This relationship is calibrated using simulated ion signals, and the calibration is compared to the HAR values measured for PEG ion signals where the ion energy was also determined using an independent method that requires that the ions be highly charged (>?300 e). The mean error of 0.6% between the two measurements indicates that the HAR method is an accurate means of ion energy determination that does not depend on ion size or charge. The HAR is determined dynamically over the entire trapping period, making it possible to observe the change in ion energy that takes place as solvent evaporates from the ion and collisions with background gas occur. This method makes it possible to measure mass changes, either from solvent evaporation or from molecular fragmentation (MSⁿ), as well as the cross sections of ions measured using CDMS.

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Graphical Abstract

     

Click chemistry in mesoporous materials: functionalization of porous silicon rugate filters

In this paper we report the use of the optical properties of porous silicon photonic crystals, combined with the chemical versatility of acetylene-terminated SAMs, to demonstrate the applicability of "click" chemistry to mesoporous materials. Cu(I)-catalyzed alkyne-azide cycloaddition reactions were employed to modify the internal pore surfaces through a two-step hydrosilylation/cycloaddition procedure. A positive outcome of this catalytic process, here performed in a spatially confined environment, was only observed in the presence of a ligand-stabilized Cu(I) species. Detailed characterization using Fourier transform infrared spectroscopy and optical reflectivity measurements demonstrated that the surface acetylenes had reacted in moderate to high yield to afford surfaces exposing chemical functionalities of interest. The porous silicon photonic crystals modified by the two-step strategy, and exposing oligoether moieties, displayed improved resistance toward the nonspecific adsorption of proteins as determined with fluorescently labeled bovine serum albumin. These results demonstrate that "click" immobilization offers a versatile, experimentally simple, and modular approach to produce functionalized porous silicon surfaces for applications as diverse as porous silicon-based sensing devices and implantable biomaterials.     

Standard Practice for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces: collaborative study

The draft ASTM Standard, "Standard Practice for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces," was validated in a collaborative study consisting of 6 teams comprised of Civil Support personnel and First Responders, 2 levels of Bacillus anthracis Sterne and Bacillus thuringiensis Kurstaki spores, and 7 nonporous surfaces. The sample collection standard includes collection of the bulk sample (Method A) using a dry swab to push the sample onto a collection card and collection of residual sample (Method B) using an onsite test kit followed by a wet swab intended for additional onsite testing. Method A is to be performed prior to Method B in order to preserve unadulterated sample as potential criminal evidence. While statistical differences were observed between surfaces, between teams, and the interaction of surfaces and teams for the various sample types collected, these differences are due to the very low variability of the data and a much more narrow distribution than an ideal normal distribution, rather than to any practical differences. The data demonstrate that from both the 1.0 and 0.01 g powder samples, high levels of spores (mean >10(6) CFU) are recovered from the 7 surfaces by both the dry swab used in bulk sample collection (Method A) and the wet swab (Method B) sampling of the residual powder after bulk sample collection. Thus, after bulk sample collection, there is a high level of residual spores remaining for onsite biological testing and both Methods A and B should be performed in the field.