The effect of hydrostatic pressure on the dielectric constants, and their temperature dependences, of phosphate and tellurite glasses

Measurements of the pressure dependence of the static dielectric constant of tellurite (pure TeO₂ and 67%TeO₂ + 33%WO₃) and samarium phosphate (5%Sm₂O₃ + 95%P₂O₅ and 15%Sm₂O₃ + 85%P₂O₅) glasses at elevated pressures (0–70 kbar) for a range of temperatures (77–380 K) are reported. The electrical properties under pressure have been determined from the low-frequency complex plane analysis of glass discs contained within a Bridgman opposed anvil cell. The most notable observation is that the pressure dependence of the static dielectric constant, of all glasses studied, is positive, for example for vitreous TeO₂ ln ε/P is equal to 4.41 × 10⁻¹¹ (Pa⁻¹) at 293 K. Behaviour of this type is common to a number of materials (plastics and chalcogenide glasses) for which it is not possible to define any long-range order. It is in direct contrast with the behaviour of crystalline insulators, for which ε/P is usually negative. The effect of pressure on the dielectric constant has been analysed using two different approaches based on the macroscopic Clausius-Mossotti equation. The effects of high pressure on the dielectric constant have been correlated with the temperature dependence of the dielectric constant at atmospheric pressure.     

Voltage control for microchip capillary electrophoresis analyses

This paper presents an inexpensive and easy-to-implement voltage sequencer instrument for use in microchip capillary electrophoresis (MCE) actuation. The voltage sequencer instrument takes a 0–5 V input signal from a microcontroller and produces a reciprocally proportional voltage signal with the capability to achieve the voltages required for MCE actuation. The unit developed in this work features four independent voltage channels, measures 105 × 143 × 45 mm (width × length × height), and the cost to assemble is under 60 USD. The system is controlled by a peripheral interface controller and commands are given via universal serial bus connection to a personal computer running a command line graphical user interface. The performance of the voltage sequencer is demonstrated by its integration with a fluorescence spectroscopy MCE sensor using pinched sample injection and electrophoretic separation to detect ciprofloxacin in samples of milk. This application is chosen as it is particularly important for the dairy industry, where fines and health concerns are associated with the shipping of antibiotic-contaminated milk. The voltage sequencer instrument presented represents an effective low-cost instrumentation method for conducting MCE, thereby making these experiments accessible and affordable for use in industries such as the dairy industry.     

Mechanochemistry: opportunities for new and cleaner synthesis

The aim of this critical review is to provide a broad but digestible overview of mechanochemical synthesis, i.e. reactions conducted by grinding solid reactants together with no or minimal solvent. Although mechanochemistry has historically been a sideline approach to synthesis it may soon move into the mainstream because it is increasingly apparent that it can be practical, and even advantageous, and because of the opportunities it provides for developing more sustainable methods. Concentrating on recent advances, this article covers industrial aspects, inorganic materials, organic synthesis, cocrystallisation, pharmaceutical aspects, metal complexes (including metal-organic frameworks), supramolecular aspects and characterization methods. The historical development, mechanistic aspects, limitations and opportunities are also discussed (314 references).     

The synthesis of 3-aryl-3-azetidinyl acetic acid esters by rhodium(I)-catalysed conjugate addition of organoboron reagents

A practical route to 3-aryl-3-azetidinyl acetic acid esters is developed. The key step involves the rhodium(I)-catalysed conjugate addition of an organoboron reagent to an α,β-unsaturated alkene. Elaboration of one conjugate addition product to give a novel spiroazetidine ring system is also described.     

Interfacial tension controlled fusion of individual femtolitre droplets and triggering of confined chemical reactions on demand

This paper describes stepwise on-demand generation and fusion of femtolitre aqueous droplets based on interfacial tension. Sub-millisecond reaction times from droplet fusion were demonstrated, as well as a reversible chemical toggle switch based on alternating fusion of droplets containing acidic or basic solution, monitored with the pH-dependent emission of fluorescein.     

High-efficiency 10 J diode pumped cryogenic gas cooled Yb:YAG multislab amplifier

We report on the first demonstration of a diode-pumped, gas cooled, cryogenic multislab Yb:YAG amplifier. The performance was characterized over a temperature range from 88 to 175 K. A maximum small-signal single-pass longitudinal gain of 11.0 was measured at 88 K. When amplifying nanosecond pulses, recorded output energies were 10.1 J at 1 Hz in a four-pass extraction geometry and 6.4 J at 10 Hz in a three-pass setup, corresponding to optical to optical conversion efficiencies of 21% and 16%, respectively. To our knowledge, this represents the highest pulse energy so far obtained from a cryo-cooled Yb-laser and the highest efficiency from a multijoule diode pumped solid-state laser system.     

Affinity prediction for substrates of the peptide transporter PepT1

A quantitative method has been developed for determining the affinity of substrates for the peptide transporter PepT1, allowing oral availability of drugs via PepT1 to be estimated.     

<Emphasis Type="Italic">Quid pro quo</Emphasis>: Reflections on the value of problem structuring group workshops

Attracting clients who are willing to invest in using a problem structuring method (PSM) can be particularly difficult for the emerging generation of modellers. There are many reasons for this, not least that the benefits of a problem structuring intervention are vague and evidence of benefits are often anecdotal for example, claims of constructing a deeper understanding of the problem or building the commitment of a group to implementing an outcome. This paper contributes to the evaluation of problem structuring methods by reflecting on the quid pro quo that a client and problem structuring modeller can enjoy from collaboration. The paper reflects on 21 cases, where Journey Making (a problem structuring method) was used with 16 organizations to help managers agree a suite of actions to tackle a complex strategic issue. The reflections are clustered around those benefits that pertain to: PSMs in general; PSMs that use computer-supported workshops; the Journey Making methodology.     

A facile two-step synthesis of 8-arylated guanosine mono- and triphosphates (8-aryl GXPs)

We report a simple and high-yielding two-step procedure for the preparation of 8-arylated guanosine mono- and triphosphates (8-aryl GXPs). The key step of our synthesis is the Suzuki-Miyaura coupling of unprotected 8-bromo GMP and 8-bromo GTP with various arylboronic acids in aqueous solution. The 8-bromoguanosine 5'-phosphates required as cross-coupling substrates were prepared from 8-bromoguanosine via an optimised Yoshikawa procedure.