Milling dynamics: Part I. Attritor dynamics: Results of a cinematographic study

The motions of grinding media and powder in an attritor canister were studied by means of filming the agitated charge and frame-by-frame scrutiny of the footage. In conjunction with auxiliary experiments, this permitted semiquantitative analysis of the milling action. In particular, the mill can be divided into several regions characterized by different balances between direct impacts and rolling/sliding of the grinding media. Simple calculations suggest that impacts are more capable of effecting mechanical alloying (MA) than are rolling or sliding events in an attritor. Powder circulation within an operating mill was also investigated. Based on the results and the accompanying analysis, concepts for improved attritor design are presented. D. Maurice is formerly a Graduate Student, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22903     

Epitope mapping of the major inner capsid protein of group A rotavirus using peptide synthesis

Nucleic acid amplification by polymerase chain reaction (PCR) is a very powerful technique in terms of sensitivity but is limited in terms of ability to perform accurate quantitation. While there is a theoretical correlation between copies of input target sequence and those of PCR product, the quantitative nature of this relationship is obscured by unpredictable variations in reaction conditions and by inhibitory and/or stimulatory substances which might be present in sample preparations, especially those derived from biological fluids. To reliably estimate copies of input DNA target from PCR product, we designed a combination of internal and external control systems coupled to DNA/RNA hybridization and enzymatic immunodetection techniques. The internal control system served to monitor amplification efficiency and to correct for the effects of inhibitors or stimuli on the efficiency of the DNA amplification. The assay is quantitative, nonisotopic, and can be widely applied to assessment of the quantity of DNA present in a wide range of preparations.     

A Cost-Optimal Pipeline Algorithm for Permutation Generation in Lexicographic Order

In this paper we solve the open problem of designing a cost-optimal parallel algorithm for generating permutations ofMelements out of the set {0, 1, …,N− 1}, in lexicographic order. Our algorithm runs on the simplest model of parallel computation, i.e., a linear array of sizeM, where each processor PE(i) needs only a constant number of words of length logN, and is responsible for producing with constant delay, theith components in the successive permutations. This algorithm runs in timeO(N!/(N−M)!) on an array of sizeMand is therefore cost-optimal when the time needed to output the permutations is taken into account. Moreover, by doubling the number of cells, it is possible to implement this algorithm on a unidirectional linear array.     

MOZAMBIQUE-MADAGASCAR GEOSYNCLINE, I: DEPOSITION AND ARCHITECTURE

The Mozambique-Madagascar geosyncline consists of an open-ended non-compressional NNE-SSW downwarp 1,700 km long in the area of the present Mozambique Channel and its bordering coastal regions. Exposed basement marks the lateral boundaries of the geosyncline, and embayments rather than discrete basins modify its regional geometry. A sedimentary volume of more than 5,000,000 cu km resulted from subsidence and hypersubsidence, not only in the Mozambique Channel but also on the coastal borders, in places relatively close to exposed basement. Continental facies of South African Karroo type dominates the sedimentary columns of the geosynclinal flanks in the Upper Carboniferous to Middle Jurassic interval, but is not yet documented beneath the bathyal and abyssal waters of the intervening Mozambique Channel. Marine facies, mixed facies, and a few continental facies occupy the sedimentary columns of the flanks above the Middle Jurassic. Pelagic facies may be dominant in contemporaneous strata now below the bottom of the Channel. As part of the vast non-compressional province of the Indian Ocean the Mozambique-Madagascar geosyncline has been subjected only to epeirogeny. The structural response has been normal faulting, in some places, with major downthrow and in others antithetic with patterns of graben and horst. Volcanism is known to have accompanied the faulting from Late Triassic time onward. Modern consensus invokes a separation of Madagascar from Africa followed by drift along southward, eastward, or NE paths, depending upon individual tectonophysical interpretation, each of the three of which displays weakness. The alternative of separation by subsidence only needs the test of deep drilling under the present Mozambique Channel for support orproof Until then, a tentative scheme of stratal succession is proposed, namely, a relatively-thin post-Karroo column in pelagic facies and a relatively-thick Karroo column in continental and mixed facies. Confirmation of the succession by drilling would provide strong support of a model presenting paleo-Madagascar as the eastern sector of an Africa that bulged more than once toward the east in post-Carboniferous time. The corollary of a broad band of reservoir Karroo, under a broad cover of pelagic post-Karroo, all under the waters of the present Mozambique Channel would be of considerable interest to explorationists.     

Self-assembling of atomic vacancies at an oxide/intermetallic alloy interface

Oxide layers grown on the surface provide an effective way of protecting metallic materials against corrosion for sustainable use in a broad range of applications. However, the growth of cavities at the metal/oxide interface weakens the adherence of the protective layer and can promote its spallation under service conditions, as observed for alumina layers formed by selective oxidation of aluminide intermetallic alloys used in high-temperature applications. Here we show that direct atomic-scale observations of the interface between an ultrathin protective oxide layer (alumina) grown on an intermetallic titanium aluminide substrate (TiAl) can be performed with techniques sensitive to the topmost atomic layers at the surface. Nanocavities resulting from the self-assembling of atomic vacancies injected at the interface by the growth mechanism of the protective oxide are observed for the first time, bringing new insight into the understanding of the fate of injected cavities in oxidation processes.     

Digital micromirror device as a spatial illuminator for fluorescence lifetime and hyperspectral imaging

Time-domain fluorescence lifetime imaging (FLIM) and hyper-spectral imaging (HSI) are two advanced microscopy techniques widely used in biological studies. Typically both FLIM and HSI are performed with either a whole-field or raster-scanning approach, which often prove to be technically complex and expensive, requiring the user to accept a compromise among precision, speed, and spatial resolution. We propose the use of a digital micromirror device (DMD) as a spatial illuminator for time-domain FLIM and HSI with a laser diode excitation source. The rather unique features of the DMD allow both random and parallel access to regions of interest (ROIs) on the sample, in a very rapid and repeatable fashion. As a consequence both spectral and lifetime images can be acquired with a precision normally associated with single-point systems but with a high degree of flexibility in their spatial construction. In addition, the DMD system offers a very efficient way of implementing a global analysis approach for FLIM, where average fluorescence decay parameters are first acquired for a ROI and then used as initial estimates in determining their spatial distribution within the ROI. Experimental results obtained on phantoms employing fluorescent dyes clearly show how the DMD method supports both spectral and temporal separation for target identification in HSI and FLIM, respectively.     

Transfer of highly hydrophilic ions from water to nitrobenzene, studied by three-phase and thin-film modified electrodes

The study by voltammetry of hydrophilic ion transfers across the interface between an aqueous solution and an immiscible organic solvent is limited by the presence of supporting electrolytes in both phases. Such a study is impossible for ions having a higher affinity for water than ions of the electrolytes. Indirectly, methods based on modified solid electrodes can be used; these are obtained by the deposition of an organic phase containing a molecule having redox properties, the modified electrode being in contact with an aqueous solution of the appropriate electrolyte. The three-phase electrode is very convenient for that purpose. However, this experimental tool also has its own limitation, due mainly to the redox species produced in the organic phase. The oxidized, or reduced, form of the redox molecule must have a very low affinity for water, as otherwise its transfer masks that of the ion under study. Ferrocene is almost useless because of the affinity of the ferrocenium cation for water, decamethylferrocene being a better choice. The present work illustrates how the use of lutetium bisphthalocyanines widely expands the possibilities, as these molecular sandwich complexes can be reduced as well as oxidized, the products of the reactions having a very low affinity for water. This made the determination of the Gibbs energy possible for the transfers of highly hydrophilic ions from water to nitrobenzene: Cl(-) (40 kJ mol(-1)), F(-) (57 kJ mol(-1)), H2PO4(-) (64 kJ mol(-1)). Nothing being really known about the transfer of F(-) or H2PO4(-) from water to organic solvents, these are the first values ever published. H(+), OH(-), and HSO4(-) have also been studied, showing that these species, which have a poor affinity for nitrobenzene, are prone to association reactions with the reduced or oxidized forms of the lutetium bisphthalocyanine.     

Pinpointing biomarkers in proteomic LC/MS data by moving-window discriminant analysis

The identification of differential patterns in data originating from combined measurement techniques such as LC/MS is pivotal to proteomics. Although "shotgun proteomics" has been employed successfully to this end, this method also has severe drawbacks, because of its dependence on largely untargeted MS/MS sequencing and databases for statistical analyses. Alternatively, several MS-signal-based (MS/MS-independent) methods have been published that are mainly based on (univariate) Student's t-tests. Here, we present a more robust multivariate alternative employing linear discriminant analysis. Like the t-test-based methods, it is applied directly to LC/MS data, instead of using MS/MS measurements. We demonstrate the method on a number of simulated data sets, as well as on a spike-in LC/MS data set, and show its superior performance over t-tests.     

Enhanced removal of Cr(VI) from aqueous solution using polypyrrole/Fe3O4 magnetic nanocomposite

Fe(3)O(4) coated polypyrrole (PPy) magnetic nanocomposite was prepared via in situ polymerization of pyrrole monomer for the removal of highly toxic Cr(VI). Structure and morphology of the prepared nanocomposite were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction pattern, Field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). Electron spin resonance (ESR) studies confirmed that the nanocomposite is magnetic in nature. Up to 100% adsorption was found with 200mg/L Cr(VI) aqueous solution at pH 2. Adsorption of Cr(VI) on the surface of the adsorbent was confirmed by the ATR-FTIR and X-ray photoelectron spectroscopy (XPS). XPS studies also suggested that ion exchange and reduction on the surface of the nanocomposite may be the possible mechanism for Cr(VI) removal by the PPy/Fe(3)O(4) nanocomposite. Adsorption results showed that Cr(VI) removal efficiency by the nanocomposite decreased with an increase in pH. Adsorption kinetics was best described by the pseudo-second-order rate model. Isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature. Desorption experiment showed that in spite of the very poor recovery of the adsorbed Cr(VI); the regenerated adsorbent can be reused successfully for two successive adsorption-desorption cycles without appreciable loss of its original capacity.     

Toward green dialysis: Focus on water savings

Hemodialysis is one of the most water and energy‐hungry medical procedures, and thus represents a clear opportunity where improvements should be made concerning the consumption and wastage of water. Three levels were investigated on which there are potential savings: the precise adjustment of water production according to specific needs, the reuse of reverse osmosis rejected water, and finally the huge volumes of post‐patient dialysate effluent. The “AURAL” (Association pour l′Utilisation du Rein Artificiel à Lyon), main unit in Lyon, was the site of investigation for this study, which cares for 173 chronic hemodialysis patients. Evaluation of the 3 levels described earlier was undertaken on this particular building, and on the water treatment currently used. Volumes of produced water can be improved by different hydraulic systems or by adjusting the pure water conductivity used for dialysis. Concerning the reject water, reuse for building sanitation became the focus of further attention. The technical feasibility, volume of saved water, and applicable work costs were considered. The results suggest that out of a possible 2834 m³/year of reject water, 1200 m³/year may be reused and return on investment recovered within 5.8 years. Finally, the reprocessing and feasibility of reuse of dialysate effluent were investigated. Initial calculations show that although technical solutions are available, such processing of the wastewater production is not profitable in the short term. Regarding the significant prior authorization and risk management analysis necessary for such a project, this avenue was pursued no further. From the perspective of a “green dialysis,” the reuse of reject water into sanitation is both viable and profitable in our unit, and must be the next step of our project. More widely, improvements can be made by defining a more precise range of pure water conductivity for dialysis and by applying reuse water project to new or to be renovated units.