Electrospinning and Imaging

Polymer processing via electrospinning is a cost effective and scalable method for preparing nanofibers with industrial, electrical, and biomedical applications, particularly tissue engineering and drug delivery. Characterization methods for these fibers include microscopy techniques for vitro surface morphology information, spectroscopy methods to determine in vitro chemical composition, and medical imaging tools for in vivo assessment of morphology and efficacy of implanted material. The focus of this paper is be on recent applications for electrospun nanofibers, in vitro characterization methods, and medical imaging modalities that can be used for in vivo assessment of the fibers, as well as insights in how to adapt existing techniques toward the characterization of electrospun materials.     

Economical emergency response and lower profile states: A behavioral health reference for the rest of us.

In some jurisdictions, major disasters rarely occur. Those responsible for providing behavioral health services in these jurisdictions have less opportunity to accrue experience and understanding of disaster and less access to behavioral health funding support and guidance than is true elsewhere. This affects both preparedness and response. The state of Oregon, a lower profile state in terms of disaster experience, participated in the national TOPOFF 4 dirty bomb exercise. With necessity serving as the mother of invention, circumstances converged to reveal alternative strategies that may serve some lower profile jurisdictions more effectively than recommended standard practice and that appear to have economical benefit. Response strategy relied on recruitment and assignment of sufficient responders by collaborating among multiple existing trained resources rather than using a state or local public health volunteer registry. It also implemented just-in-time trainings and took advantage of other spontaneous teaching opportunities rather than relying on the efficacy of more costly traditional training models. Potential strategies for more economical preparedness and response activity and recommendations for addressing some current national shortcomings are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Uranium Exploration in the United States

The United States Atomic Energy Commission looks to the private prospector and the mining industry to assure the success of our uranium exploration program. We believe that industry is certain to increase its activity in the field rapidly as the economic importance of uranium to its operations is more fully realized. The contribution made by educational institutions and by other government agencies in developing and distributing information is recognized by the Commission as an important phase of the program.

Progress is being made in the discovery of ore and the development of ore-finding techniques on the Colorado Plateau, which is the most important uranium-producing region in the United States. Other areas of primary and secondary uranium mineralization, such as the Colorado Front Range, the newly discovered deposits in the Sunshine Mine in Idaho, the Marysvale, Utah, area, and the Upper Peninsula of Michigan, show promise for future production. Evaluation of potential low-grade uranium ores such as the phosphate rocks of Florida and the northwestern states, and the black shales of Tennessee and Kentucky, has been substantially completed.

The Commission's exploration program will, we believe, assure the United States of a growing supply of domestic uranium ore. Together with the results of the Canadian exploration activities, which are most encouraging, our program should provide increasing resources of this all-important material, and should further reduce our dependence on supplies from overseas.     

Developing an Antibody–Drug Conjugate Approach to Selective Inhibition of an Extracellular Protein

Antibody–drug conjugates (ADCs) are a growing class of therapeutics that harness the specificity of antibodies and the cell-killing potency of small-molecule drugs. Beyond cytotoxics, there are few examples of the application of an ADC approach to difficult drug discovery targets. Here, we present the initial development of a non-internalising ADC, with a view to selectively inhibiting an extracellular protein. Employing the wellinvestigated matrix metalloproteinase-9 (MMP-9) as our model, we adapted a broad-spectrum, nonselective MMP inhibitor for conjugation and linked this to a MMP-9-targeting antibody. The resulting ADC fully inhibits MMP-9, and ELISA results suggest antibody targeting can direct a nonselective inhibitor.     

Stepwise transplantation of an active site loop between heat-labile enterotoxins LT-II and LT-I and characterization of the obtained hybrid toxins

Members of the cholera toxin family, including Escherichia coli heat- labile enterotoxins LT-I and LT-II, catalyze the covalent modification of intracellular proteins by transfer of ADP-ribose from NAD to a specific arginine of the target protein. The ADP-ribosylating activity of these toxins is located in the A-subunit, for which LT-I and LT-II share a 63% sequence identity. The flexible loop in LT-I, ranging from residue 47 to 56, closes over the active site cleft. Previous studies have shown that point mutations in this loop have dramatic effects on the activity of LT-I. Yet, in LT-II the sequence of the equivalent loop differs at four positions from LT-I. Therefore five mutants of the active site loop were created by a stepwise replacement of the loop sequence in LT-I with virtually all the corresponding residues in LT- II. Since we discovered that LT-II had no activity versus the artificial substrate diethylamino-benzylidine-aminoguanidine (DEABAG) while LT-I does, our active site mutants most likely probe the NAD binding, not the arginine binding region of the active site. The five hybrid toxins obtained (Q49A, F52N, V53T, Q49V/F52N and Q49V/F52N/V53T) show (i) great differences in holotoxin assembly efficiency; (ii) decreased cytotoxicity in Chinese hamster ovary cells; and (iii) increased in vitro enzymatic activity compared with wild type LT-I. Specifically, the three mutants containing the F52N substitution display a greater Vmax for NAD than wild type LT-I. The enzymatic activity of the V53T mutant is significantly higher than that of wild type LT-I. Apparently this subtle variation at position 53 is beneficial, in contrast to several other substitutions at position 53 which previously had been shown to be deleterious for activity. The most striking result of this study is that the active site loop of LT- I, despite great sensitivity for point mutations, can essentially be replaced by the active site loop of LT-II, yielding an active 'hybrid enzyme' as well as 'hybrid toxin'.      

INTERFEROMETER MEASUREMENTS OF THE THERMAL DILATATION OF GLAZED WARE1

The network of fine cracks often seen in the surface of glazed products not only mars the surface but shortens the life and lowers the price of the ware. Since the relative expansivity of the glaze and body is a very important factor in controlling this condition reliable measurements of both are of the utmost importance. Until recently the difficulty has been that the expansivity of the glaze has been measured on specimens of the material melted to glass and drawn into rods or cast in molds of sufficient length. Owing to the difference between this treatment and that received by the material when spread on the ware, it was realized that these methods might lead to unavoidable errors. By the interference method, specimens 0.2 mm. in length can be measured with sufficient accuracy. Therefore in measuring glazes the samples may be taken directly from the finished ware. In this paper the thermal expansion of glaze materials prepared in the form of drawn glass or cast rods is compared with that of the same material taken from the finished ware. From the measurements, the expected divergence is found to be as much as 20% in the case of drawn glass specimens, and 10% for cast specimens.     

Interferometric chromatic dispersion measurements on short lengthsof monomode optical fiber

Chromatic dispersion measurements on short lengths of monomode optical fiber by the technique of `white light' interferometry are presented. Improved optoelectronic signal processing and rigorous data reduction techniques have resulted in a temporal resolution of ⩾7×10^-5 ps·nm^-1 in a 1-m length of fiber, equivalent to 0.06% resolution in the measurement technique. This is equivalent to a first-order chromatic dispersion coefficient ( D(λ)) resolution of 0.07 ps·nm^-1·^-1. The second-order chromatic dispersion coefficient (S(λ)) resolution was 0.02 ps·nm^-2·nm^-1. Experimental results of D(λ) and S(λ) for three different fibers are compared to theoretical calculation of material and waveguide dispersion     

Structure and property study of nylon‐6/clay nanocomposite fiber

The crystal structures of nylon‐6 and nylon‐6/clay fibers were investigated on annealing and drawing. Annealing increased the γ‐crystalline form of both fibers, as indicated by the DSC curves, and its effect was dominant in nylon‐6/clay fiber. On drawing, the γ‐crystalline form was easily converted into the α form in nylon‐6, whereas it was still observed at a relatively high spin‐draw ratio in nylon‐6/clay fiber. However, although the α‐crystal form was dominant in nylon‐6, the γ‐crystal form was dominant in nylon‐6/clay with annealing and drawing, on the basis of the XRD data. The fast crystallization rate of nylon‐6/clay compared with pure nylon‐6 was confirmed, on the basis of the Avrami exponent. The initial modulus of nylon‐6/clay fiber was 30 % higher than the neat nylon‐6 fiber. The reinforcing effect of clay on the dynamic storage modulus was observed. Copyright © 2004 Society of Chemical Industry     

Synthesis and properties of star-like wholly aromatic polyester fibers

Novel star-like wholly aromatic copolyesters having four arms based on a tetraamine star core, p- and m- hydroxybenzoic acids and 6-hydroxy-2-naphthoic acid have been successfully synthesized and spun into fibers for the investigation of the effect of the star-like structure on improving compressive properties of the fiber. The reactivity of the star core was demonstrated using a model compound with FTIR, ¹H and ¹³C NMR spectroscopy. The ¹³C NMR spectrum of the star-like terpolymer having a molar ratio of 10:1 of the monomers to star core showed a characteristic peak at around δ62 ppm which corresponds to a tetra-substituted carbon and thereby demonstrates that the star core was really incorporated into the polymer. The star-like copolyester exhibited a clear stir opalescence and liquid crystalline morphology in the temperature range of 150-280 °C. However, no transition was observed in the DSC thermogram except a clear T_g at 110 °C. The star-like terpolymer fiber, prepared from a polymer with a molar ratio of 500:1 for the monomers to imide core, was spun in the liquid crystalline state at 180 °C. Fiber structure and properties have been studied.