Habit Modifications of Nitrofurantion Crystallized from Formic Acid Mixtures

The crystal size and the length to width ratio of Nitrofurantoin, an anti-bacterial urinary tract drug, can be controlled using an appropriate mixture of solvents and suitable crystallization conditions.

Some solvents will form undesirable complexes with the drug (INF) while with others no crystal structure modification or complexation was detected (HCO₂H).

The length (y) to width (x) ratio of the Nitrofurantoin varies from 2.5 to 1.5 when crystallized from pure formic acid or in a mixture with water or ethanol.

The y/x values correspond to the solvent interactions and super saturation (S).

The crystal growth regularity is ascribed to the solvent power and thus when more regular crystals will precipitate bioavailability and solubilization of the drug will increase. Best results were obtained when mixture of formic acid-ethanol solution was used as crystallization media yielding large tabular crystals.     

Polyglycerol esters composition: Theoretical random distribution versus HPLC analysis

Product composition of polyglycerol esters, prepared from a direct alkaline polymerization of glycerol followed by esterification with stearic or oleic acids, has been studied. The internal product composition, as analyzed by high performance liquid chromatography (HPLC), shows clearly that in contradiction to what has been published recently, the fatty acid radicals arenot distributed at random among all available hydroxyl groups, and thus, any theoretical calculation on the product composition could not be correct. The product composition of the crude material indicates clearly that the internal positions (secondary hydroxyls) of the glycerol polymer are esterified with greater difficulty than the primary hydroxyl groups.     

Fairness in context-free grammars under every choice-strategy

In (Porat et al., 1982, Inform. and Control 55, 108–116) the notion of fair derivations in context-free grammars was introduced and studied. The main result there is a characterization of fairly terminating grammars as non-variable-doubling. In this paper we show that the same characterization is valid under canonical derivations in which the next variable to be expanded is deterministically chosen, leaving nondeterminism only to the decision as to which rule (of the chosen variable) to apply. Two families of canonical derivations are introduced and studied as special cases: spinal derivations and layered derivations.     

Certificate revocation and certificate update

We present a solution for the problem of certificate revocation. This solution represents certificate revocation lists by authenticated dictionaries that support: (1) efficient verification whether a certificate is in the list or not and (2) efficient updates (adding/removing certificates from the list). The suggested solution gains in scalability, communication costs, robustness to parameter changes, and update rate. Comparisons to the following solutions (and variants) are included: “traditional” certificate revocation lists (CRLs), Micali's (see Tech. Memo MIT/LCS/TM-542b, 1996) certificate revocation system (CRS), and Kocher's (see Financial Cryptography-FC'98 Lecture Notes in Computer Science. Berlin: Springer-Verlag, 1998, vol.1465, p.172-7) certificate revocation trees (CRT). We also consider a scenario in which certificates are not revoked, but frequently issued for short-term periods. Based on the authenticated dictionary scheme, a certificate update scheme is presented in which all certificates are updated by a common message. The suggested solutions for certificate revocation and certificate update problems are better than current solutions with respect to communication costs, update rate, and robustness to changes in parameters, and are compatible, e.g., with X.500 certificates     

Data and models for metonymy resolution

We describe the first shared task for figurative language resolution, which was organised within SemEval-2007 and focused on metonymy. The paper motivates the linguistic principles of data sampling and annotation and shows the task’s feasibility via human agreement. The five participating systems mainly used supervised approaches exploiting a variety of features, of which grammatical relations proved to be the most useful. We compare the systems’ performance to automatic baselines as well as to a manually simulated approach based on selectional restriction violations, showing some limitations of this more traditional approach to metonymy recognition. The main problem supervised systems encountered is data sparseness, since metonymies in general tend to occur more rarely than literal uses. Also, within metonymies, the reading distribution is skewed towards a few frequent metonymy types. Future task developments should focus on addressing this issue.

High pressure ellipsometry: a novel method for measuring the optical properties and electronic structure of materials in diamond anvil cells

High pressure ellipsometry (HPE) method was developed for determining the index of refraction of opaque materials in a diamond anvil cell (DAC). A main difficulty in DAC-based HPE, namely, the pressure-induced birefringence developed in the diamond, was overcome enabling the extraction of the ellipsometric parameters of the sample. The method used was based on the fact that an unpolarized light is unaffected by a retarding optical element and thus reduces the number of unknown parameters in the problem. Because of technical difficulties in using unpolarized light, a linear combination of orthogonal polarizations was applied. In the experimental procedure, multiangle measurements of the ellipsometric parameter ψ are collected at each pressure and the data is fitted together with a measurement of the near normal reflectivity, in order to extract the complex index of refraction. As a test case, this procedure was used to measure the high pressure index of refraction of iron up to 30 GPa for light with wavelengths of 532 and 633 nm. From the index of refraction as a function of pressure the diamond-iron interface emissivity for different pressures was derived and from which the phase transition α → ε could be identified and characterized. The emissivity increases with pressure both at the α (0-9 GPa) and the ε phase (21-30 GPa) however decreases at the mixed α - ε (9-21 GPa) range. From the imaginary part of the index of refraction the pressure dependence of the energy skin depth of iron was extracted. It was found that the energy skin depth increases by an order of magnitude at 30 GPa relative to ambient conditions.     

Engineering performance in applied EPD: problems and solutions

Providing the particle size, shape and size distribution are suitable, appropriate dispersion media and surface-active additives can usually be found for the electrophoretic deposition (EPD) of powder with any chemical composition. The design of the EPD cell is largely dictated by the geometry of the final product and the required dimensional tolerances. The integrity of the microstructure and freedom of the product from process defects commonly depend on the deposition parameters and the dispersion chemistry.Demonstrations of laboratory feasibility for EPD products may prove straightforward, but developing an EPD process technology that is suitable for mass production can be far more challenging. This contribution reports four examples:

Topographic profiling and refractive-index analysis by use of differential interference contrast with bright-field intensity and atomic force imaging

A methodology is described for phase restoration of an object function from differential interference contrast (DIC) images. The methodology involves collecting a set of DIC images in the same plane with different bias retardation between the two illuminating light components produced by a Wollaston prism. These images, together with one conventional bright-field image, allows for reduction of the phase deconvolution restoration problem from a highly complex nonlinear mathematical formulation to a set of linear equations that can be applied to resolve the phase for images with a relatively large number of pixels. Additionally, under certain conditions, an on-line atomic force imaging system that does not interfere with the standard DIC illumination modes resolves uncertainties in large topographical variations that generally lead to a basic problem in DIC imaging, i.e., phase unwrapping. Furthermore, the availability of confocal detection allows for a three-dimensional reconstruction with high accuracy of the refractive-index measurement of the object that is to be imaged. This has been applied to reconstruction of the refractive index of an arrayed waveguide in a region in which a defect in the sample is present. The results of this paper highlight the synergism of far-field microscopies integrated with scanned probe microscopies and restoration algorithms for phase reconstruction.     

Heat capacity of tristearin in the presence of food emulsifiers

The specific heats of tristearin in the presence of some food emulsifiers were determined by differential scanning calorimetry. Solid emulsifiers show Cp curves different from those of pure tristearin, indicating that a new mixed crystal has been obtained through the incorporation of the surfactant within the fat.