A thermally actuated microgripper as an electrochemical sensor with the ability to manipulate single cells

The design and fabrication of a thermally actuated polymeric microgripper incorporating a bare gold working electrode is described. Initial electrochemical tests confirm that the microgripper sensor works as an effective microelectrode, opening up exciting possibilities in single cell measurements.     

MALDI imaging mass spectrometry of β‐ and γ‐crystallins in the ocular lens

Lens crystallin proteins make up 90% of expressed proteins in the ocular lens and are primarily responsible for maintaining lens transparency and establishing the gradient of refractive index necessary for proper focusing of images onto the retina. Age‐related modifications to lens crystallins have been linked to insolubilization and cataractogenesis in human lenses. Matrix‐assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) has been shown to provide spatial maps of such age‐related modifications. Previous work demonstrated that, under standard protein IMS conditions, α‐crystallin signals dominated the mass spectrum and age‐related modifications to α‐crystallins could be mapped. In the current study, a new sample preparation method was optimized to allow imaging of β‐ and γ‐crystallins in ocular lens tissue. Acquired images showed that γ‐crystallins were localized predominately in the lens nucleus whereas β‐crystallins were primarily localized to the lens cortex. Age‐related modifications such as truncation, acetylation, and carbamylation were identified and spatially mapped. Protein identifications were determined by top‐down proteomics analysis of lens proteins extracted from tissue sections and analyzed by LC‐MS/MS with electron transfer dissociation. This new sample preparation method combined with the standard method allows the major lens crystallins to be mapped by MALDI IMS.     

Total Synthesis of (±)-Phyllantidine: Development and Mechanistic Evaluation of a Ring Expansion for Installation of Embedded Nitrogen-Oxygen Bonds

The development of a concise total synthesis of (±)-phyllantidine ( 1 ), a member of the securinega family of alkaloids containing an unusual oxazabicyclo[3.3.1]nonane core, is described. The synthesis employs a unique synthetic strategy featuring the ring expansion of a substituted cyclopentanone to a cyclic hydroxamic acid as a key step that allows facile installation of the embedded nitrogen-oxygen (N−O) bond. The optimization of this sequence to effect the desired regiochemical outcome and its mechanistic underpinnings were assessed both computationally and experimentally. This synthetic approach also features an early-stage diastereoselective aldol reaction to assemble the substituted cyclopentanone, a mild reduction of an amide intermediate without N−O bond cleavage, and the rapid assembly of the butenolide found in ( 1 ) via use of the Bestmann ylide.     

User-friendly statistical concepts for process monitoring

Many standard statistical process control techniques involve sophisticated mathematical concepts, which are frequently misunderstood and misused by their users. This means, as this paper argues, that the techniques, and the terminology and concepts underlying them, are inappropriate for their intended uses and users. The paper considers the areas of the statistical background which cause difficulties. It goes on to describe some alternative concepts, techniques and terminology, which are likely to be conceptually simpler and more ‘user-friendly’ (and in some cases more accurate and robust). None of the ideas require users to be familiar with the standard deviation. We also suggest that the approach of reengineering the conceptual background to suit the context of users and uses may be appropriate to other areas of practical statistics and OR. The paper identifies some general principles for achieving this.     

Cathodic-arc plasma density, radial profile, and total plasmainventory as measured by microwave interferometer and Faraday cup

The total amount of plasma, peak plasma density, and plasma density radial profile are derived from a series of measurements of ion current density (with a Faraday cup) and integrated electron line density (with a microwave interferometer) for a cathodic arc derived plasma. Comparisons are made between cathode material (erbium and titanium), arc current, background gas pressure, and the presence or absence of a series magnetic solenoid around the coaxial anode and cathode     

Synthesis and scintillating efficiencies of 4-functionalised-2,5-diphenyloxazoles

A series of 4-functionalised-2,5-diphenyloxazoles has been synthesised. Each member of the series has been assessed for the ability to scintillate in the presence of ionising radiation. The scintillation counting efficiency of each member of the series has been determined relative to 2,5-diphenyloxazole, a widely used scintillant molecule.     

Electroporation of Pink-Pigmented methylotrophic bacteria

Electroporation conditions were determined for electroporating the broad-host-range plasmid pHX200V-47-ml (22.4 kb) into four pink-pigmented methylotrophic strains (Methylophilus methylotrophus AS1,Methylobacterium extorquens AM1,Methylobacterium organophilum XX, andPseudomonas sp. M27). For these methylotrophs, a high electric-field strength (15 kV/cm) and high DNA concentration (18.75 ng/μI competent cells) were necessary to produce plasmid-containing cells. The addition of 30% polyethylene glycol (PEG) to the electrocompetent cells resulted in a five-to six-fold increase in electroporation efficiency in strainsM. methylotrophus AS1, M.extorquens AM1, andM. organophilum XX, and also allowed successful electroporation ofPseudomonas sp. M27 (no electroporants were obtained without PEG). The maximum electroporation efficiencies for M.methylotrophus AS1, M.extorquens AM1, M.organophilum XX, andPseudomonas sp. M27 were 1.31 X 10³, 2.57 X 10³, 5.25 x 10³, and 1.2 x 10⁴ electroporants/(μg DNA, respectively). This, along with our previous article (1), are the first reports of a plasmid being successfully electroporated into these strains.     

Stochastic electron heating in a capacitive RF discharge withnon-Maxwellian and time-varying distributions

In capacitively coupled radio frequency discharges, the electrons gain and lose energy by reflection from oscillating, high voltage sheaths. When time-averaged, this results in stochastic heating, which at low pressure is responsible for most of the electron heating in these discharges. Previous derivations of stochastic heating rates have generally assumed that the electron distribution is a time-invariant, single-temperature Maxwellian, and that the sheath motion is slow compared to the average electron velocity, so that electrons gain or lose a small amount of energy in each sheath reflection. Here we solve for the stochastic heating rates in the opposite limit of fast sheath motion and consider the applicability of the slow and fast sheath equations in the intermediate region. We also consider the effect of a two-temperature Maxwellian distribution on particle balance and the effect of a time-varying temperature on the heating rates and densities