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  • 2000-2004  (41)
  • 1995-1999  (53)
  • 1970-1974  (11)
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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 15120-15128 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 11 (1995), S. 4180-4182 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 7469-7477 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The influence of charge on diffusion in porous media was studied for fluorescent colloidal silica spheres diffusing in a porous glass medium. The bicontinuous porous silica glasses were optically matched with an organic solvent mixture in which both glass and tracers are negatively charged. Using fluorescence recovery after photobleaching, the long-time self-diffusion coefficient DSL of the confined silica particles was monitored in situ as a function of the ionic strength and particle to pore size ratio. At high salt concentration DSL reaches a relatively high plateau value, which depends on the particle to pore size ratio. This plateau value is unexpectedly higher than the value found for uncharged silica spheres in these porous glasses, but still significantly smaller than the free particle bulk diffusion coefficient of the silica spheres. At low salt concentration DSL reduces markedly, up to the point where colloids are nearly immobilized. This peculiar retardation probably originates from potential traps and barriers at pore intersections due to deviations from cylinder symmetry in the double layer interactions between tracers and pore walls. This indicates that diffusion of charged particles in tortuous porous media may be very different from transport in long capillaries without such intersections. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 419 (2002), S. 353-354 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] To create new electronic devices, physicists and engineers have had to rely increasingly on the originality of chemists in designing, synthesizing and characterizing molecular systems possessing useful properties. Exciting results have been obtained with both polymer-based light-emitting diodes and ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 429 (2004), S. 857-860 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The determination of molecular masses from barometric sedimentation profiles, a main topic in ultracentrifugal analysis, is thought to be quantitatively correct for non-interacting particles. Whereas this expectation is justified for uncharged colloids or macromolecules at low volume fractions, ...
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This study evaluated the use of black carp Mylopharyngodon piceus and salinity manipulation for controlling the infection of channel catfish Ictalurus puncratus by a digenetic trematode (tentatively identified as Bolbophorus confusus). Control methods focussed mainly on the eradication of the intermediate snail host, the marsh rams-horn Phanorbella trivolvis (previously referred to as Helisoma trivolvis), and were evaluated in laboratory tests and field experiments at a commercial catfish culture facility in southern Louisiana that was seriously impacted by the trematode. Introduction of fingerling black carp into catfish ponds at a density of 62 carpha resulted in an almost total elimination of P. trivolvis. The farm is now successfully using a facility-wide stocking rate of 40 carp/ha. Laboratory experiments were conducted to investigate the effect of salinity manipulation using NaCl on free-swimming trematode cercariae, the snail P. trivolvis, and catfish fingerlings infected with the cercariae. A salinity of 2.5 ppt had a detrimental effect on snail survival, growth, and reproduction. Salinity did not have a negative effect on the other two aspects of the trematode life cycle tested (in fact, survival of both cercariae and infected catfish fingerlings showed a positive dependence on NaCl over the 0–2.5 ppt range). A field-experiment was then conducted in catfish ponds maintained at three salinities (2.5, 1.25, and 0.25 ppt) with rock salt, NaCl. Snail densities in ponds at 2.5 ppt salinity were consistently lower than in the other treatments and no trematode infection was noted among snails or catfish in the 2.5 ppt salinity ponds. Both the use of 2.5 ppt NaCl and black carp appear valuable management tools for controlling the digenetic trematode in caffish ponds.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1570-7458
    Keywords: spruce budworm ; styloconic sensilla ; chemosensilla ; electrophysiology ; gustation ; sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Female fourth- and sixth-instar larvae, Choristoneura fumiferana, were tested individually for the response of the sugar cell on the lateral styloconic sensillum to 25 mM/l concentrations of 12 carbohydrates. The spruce budworm showed an age-related change in responsiveness of the sugar cell. The order of stimulating effectiveness for fourth-instars was melibiose 〉 sucrose 〉 raffinose.These storage di- and trisaccharides are present in the host plant at the beginning of budbreak. Sixth-instars responded to sucrose 〉 fructose〉 m-inositol. These findings are in accordance with those of a previous behavioural study on feeding preferences of sixth-instars. The response for both melibiose and raffinose does not change from fourth- to sixth-instars; however, it does for sucrose, fructose and m- inositol.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 86 (1998), S. 89-96 
    ISSN: 1570-7458
    Keywords: spruce budworm ; amino acids ; chemosensilla ; electrophysiology ; gustation ; Lepidoptera ; Tortricidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An electrophysiological approach was used to record the responses of maxillary styloconic sensilla of fourth- and sixth-instar larvae of the spruce budworm Choristoneura fumiferana to 14 amino acids. One cell in the lateral styloconic sensillum was identified as an amino acid-sensitive neuron. All of the amino acids tested, except l-proline and l-arginine, were detected by this cell. Arginine did not evoke a response from either the medial or lateral styloconic sensilla. Proline evoked responses from a cell in the medial styloconic sensillum. It is known from previous behavioural work that l-proline is a phagostimulant and l-valine inhibits feeding in Choristoneura; we thus further characterized the responses to these two amino acids. For both instars, l-proline was detected as low as 0.001 mmol/l and the maximal response was at 50 mmol/l. Stimulation of fourth- and sixth-instar larvae with l-valine showed that the maximum firing frequency was obtained at 1 mmol/l. Above and below this concentration, firing frequency decreases. Sensory responses to the amino acids stimuli did not correlate with known behavioral responses to similar stimuli.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1570-7458
    Keywords: spruce budworm ; styloconic sensilla ; balsam fir extracts ; chemosensory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An electrophysiological study of the sensilla styloconica of the galea in Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae) larvae showed a differential response between fourth- and sixth-instars to extracts of balsam fir foliage. Larvae raised on artificial diet were stimulated with the water soluble fraction of needle extracts obtained from terminal and lateral shoots of 30- and 70-yr-old balsam fir trees. An extract-sensitive neuron was found in the lateral styloconic sensillum of both instars. The lateral styloconica in the fourth-instar larvae were more sensitive to extracts from terminal than from lateral shoot foliage of both young and old trees. The lateral styloconica of sixth-instar larvae were more sensitive to lateral shoot foliage of old trees. Results are discussed with respect to their relationship to feeding preferences and feeding rates observed in a previous behavioural study.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-8781
    Keywords: microneedle ; microfluidie ; polysilicon ; cromolding ; drug delivery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A two-wafer polysilicon micromolding process has been developed for the fabrication of hollow tubes useful for microfluidic applications. These small tubes can be fabricated with a pointed end, resulting in a micro hypodermic injection needle. Microneedles are desired because they reduce both insertion pain and tissue damage in the patient. Such microneedles may be used for low flow rate, continuous drug delivery, such as the continuous delivery of insulin to a diabetic patient. The needles would be integrated into a short term drug delivery device capable of delivering therapeutics intradermally for about 24 hours. In addition, microneedles can be used for sample collection for biological analysis, delivery of cell or cellular extract based vaccines, and sample handling providing interconnection between the microscopic and macroscopic world. The strength of microneedles was examined analytically, experimentally and by finite element analysis. Metal coatings provide significant increases in the achievable bending moments before failure in the needles. For example, a 10 μ m platinum coating increased the median bending moment of a 160 μ m wide, 110 μ m high microneedle with a 20 μ m wall from 0.25 to 0.43 mNm. In addition, fluid flow in microneedles was studied experimentally. Microneedles 192 μ m wide, 110 μ m high and 7 mm long have flow rates of 0.7 ml/sec under a 138 kPa inlet pressure. This flow capacity exceeds previous microneedle capacities by an order of magnitude.
    Type of Medium: Electronic Resource
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