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A study was made of the in vivo detectability of a pH-sensitive, imidazolidine spin probe, and the efficacy of low-frequency electron spin resonance (ESR)-based techniques for pH measurement in vitro and in vivo in rats. The techniques used were longitudinally-detected ESR (LODESR) and field-cycled dynamic nuclear polarization (FC-DNP) for in vitro and in vivo measurements, and radiofrequency (RF)-and X-band ESR for comparisons in vitro. The spin probe was hexamethyl imidazolidine (HMI) with a pK of 4.6. All techniques detected HMI. Detection by FC-DNP implies coupling between the free radical and solvent water spins. Separations between the three spectral lines of the nitroxide radical, relative to measurement frequency, were consistent with theory. The overall spectrum width from unprotonated HMI (pH > pK) was greater than that from protonated agent (pH < pK). This was observed in vitro and in vivo. Longer-term studies showed that HMI is detectable and has the same spectral width (i.e., is at the same pH) up to 2 hr after gavage into the stomach, although the magnitude of the signal decreases rapidly during the first hour. The imidazoline and imidazolidine nitroxide radicals show a reversible pH effect in their electron spin resonance (ESR) spectra. This was described in 1982 (1,2), when it was demonstrated that the N-3 atom of the ring can take up a proton in an acidic environment, resulting in a change in the unpaired electron density at the N-1 atom (3) (see Fig. 1). Studies of this effect were recently reviewed by Khramtsov and Volodarsky (4). The compound 2,2,3,4,5,5-hexamethylimidazolidine-1-yloxy (referred to here as HMI), when studied by ESR spectroscopy at Xband (9.2 GHz) or lower frequencies, has a smaller hyperfine coupling constant in an acid environment (i.e., when protonated) than it does in a more alkaline environment. When measured by ESR, this effect demonstrates a pK (the pH at which half the agent is protonated) of about 4.6 (5). Khramtsov and Volodarsky (4) showed that at high measurement frequencies (140 GHz), at pH 4.7, the spectrum from HMI consists of two partially superimposed triplets: one deriving from the protonated HMI(H ϩ ) state, and one from the unprotonated state. At lower frequencies (X-band and below), however, the triplets overlap more closely and appear as single low-and mid-field lines with a partial doubling of the high-field line in the X-band spectrum (4). At 1.1 GHz there is a broadening of both high-and lowfield lines (6). When the spectrum is observed at a pH value other than its pK, one of the triplets dominates and the spectrum appears as a simple triplet with a narrower splitting for HMI in acid solution and a wider splitting at higher pH. The relative proportion of the two triplets making up the spectrum varies with pH over a substantial range, permitting the effect to be used as an ESR-based pH meter (1). The effect has been observed to occur at very low measurement frequencies (280 MHz) in solutions of HMI studied in vitro (5), and may therefore be of value for...

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Lack of industrially available materials for additive manufacturing (AM) of metallic materials along with the promises of materials with improved or unique properties provides a strong drive for developing new process/material combinations. As powder bed technologies for metallic materials are relatively new to the market, and to some extent are only maturing, developers of new process/material combinations have certain challenges to overcome. Firstly, basic knowledge on the behavior of materials (even those well established for other applications) under extreme conditions of melting/solidification with beam-based AM methods is far from being adequate. Secondly, manufacturing of the equipment is up to date driven by industrial application, thus optimization of the AM machines for small test batches of powders is still belongs to research and development projects. Also, majority of the powder manufacturers are primarily driven by the market development, and even they are well aware of the demands imposed by the powder bed AM machines, availability of small test batches of adequate powders may be problematic or at least quite costly for the R&D oriented users. Present paper describes the experiences in developing new materials for EBM A2 machine by Arcam EBM, modified for operating with powder batches of 100-200 ml and less. In particular it discusses achievements and challenges of working with powders from different materials with specifications far beyond the range suggested by machine manufacturer. Also it discusses the possibility of using blended rather than pre-alloyed powders for achieving both composite-like and alloyed materials in the same part by steering electron beam energy deposition strategy.

Smart Diaper Moisture Detection System described Is a paper-based disposable moistureactivated RPID system that could be incorporated into the traditional cellulosebased diaper. The tag is semi-passive in the sense that it has no internal battery but incorporates a built-in energy conversion sensor (Action-Activated Tag). The tag with sensor unit is optimized for low-cost manufacturing, utilizes screen-printing with electrically conductive ink on paper-based substrates and inherlts very low EM radiatlon. A discussion on the manuhctnrabilily and cost efliciency of the system is presented. A prototype system is shown and other possible application areas of the system are mentioned.

We have designed and constructed RF coil assemblies and the appropriate instrumentation for combining proton NMR imaging with LODESR imaging. This has enabled us to collect sequential images from the same sample using both methods. The coil assembly consists of a crossed ellipse coil for LODESR and proton NMR signal detection and a saddle coil for excitation of the ESR resonance. Images have been collected of phantoms containing copper sulphate and Tempol solutions. NMR images were collected (4.3 min) and within 30 s LODESR data collection started (collection time 2.5 min). Only the Tempol solutions are visible in the LODESR images.

Oncogenic hyperplasia is the first and inevitable stage of formation of a (solid) tumor. This stage is also the core of many other proliferative diseases. The present work proposes the first minimal model that combines homeorhesis with oncogenic hyperplasia where the latter is regarded as a genotoxically activated homeorhetic dysfunction. This dysfunction is specified as the transitions of the fluid of cells from a fluid, homeorhetic state to a solid, hyperplastic-tumor state, and back. The key part of the model is a nonlinear reaction-diffusion equation (RDE) where the biochemical-reaction rate is generalized to the one in the wellknown Schlögl physical theory of the non-equilibrium phase transitions. A rigorous analysis of the stability and qualitative aspects of the model, where possible, are presented in detail. This is related to the spatially homogeneous case, i.e. when the above RDE is reduced to a nonlinear ordinary differential equation. The mentioned genotoxic activation is treated as a prevention of the quiescent G0-stage of the cell cycle implemented with the threshold mechanism that employs the critical concentration of the cellular fluid and the nonquiescentcell-duplication time. The continuous tumor morphogeny is described as a time-space-dependent cellular-fluid concentration. There are no sharp boundaries (i.e. no concentration jumps exist) between the domains of the homeorhesis-and tumor-cell populations. No presumption on the shape of a tumor is used. To estimate a tumor in specific quantities, the model provides the time-dependent tumor locus, volume, and boundary that also points out the tumor shape and size. The above features are indispensable in the quantitative development of antiproliferative drugs or therapies and strategies to prevent oncogenic hyperplasia in cancer and other proliferative diseases. The work proposes an analytical-numerical method for solving the aforementioned RDE. A few topics for future research are suggested.

It becomes more and more common to print tag antennas using electrically conductive ink for massproduced Radio Frequency IDentification (RFID) tags. Electrical properties of the ink are mostly determined by conductive (e.g. silver) particles mixed into the ink solution. Since silver is relatively expensive it is desirable to minimize the amount of ink used per antenna. This paper illustrates how the printed conductor area of the antenna can be reduced by applying a grid pattern to an existing antenna geometry and to what extent the gridding can be performed without significantly degrading of the antenna electrical properties. Two common antenna structures are used as an example. It is also shown that by slightly modifying the original antenna geometry it is possible to even further reduce the amount of used ink.