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1.
Talanta ; 55(3): 551-60, 2001 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-18968400

RESUMEN

First, a novel calibration method is used to expand the current understanding of spherical drop growth and elongation that occurs during on-line measurements of surface pressure using the dynamic surface tension detector (DSTD). Using a novel surface tension calibration method, the drop radius is calculated as a function of time from experimental drop pressure data and compared to the theoretical drop radius calculated from volumetric flow rate. From this comparison, the drop volume at which the drop shape starts to deviate ( approximately 4 mul) from a spherical shape is readily observed and deviates more significantly by approximately 6 mul drop volume (5% deviation in the ideal spherical drop radius) for the capillary sensing tip employed in the DSTD. From this assessment of drop shape, an experimental method for precise drop detachment referred to as pneumatic drop detachment is employed at a drop volume of 2 mul (two second drops at 60 mul/min) in order to provide rapid dynamic surface tension measurements via the novel on-line calibration methodology. Second, the DSTD is used to observe and study kinetic information for surface-active molecules and association complexes adsorbing to an air-liquid drop interface. Dynamic surface tension measurements are made for sodium dodecyl sulfate (SDS) in the absence and presence of either tetra butyl ammonium (TBA) or chromium (III). Sensitive, indirect detection of chromium and other multiply charged metals at low concentrations is also investigated. The DSTD is utilized in examining the dynamic nature of SDS: cation association at the air-liquid interface of a growing drop. Either TBA or Cr(III) were found to substantially enhance the surface tension lowering of dodecyl sulfate (DS), but the surface tension lowering is accompanied by a considerable kinetic dependence. Essentially, the surface tension lowering of these DS: cation complexes is found to be a fairly slow process in the context of the two second DSTD measurement. The limit of detection for both SDS and chromium (III) is in the 300-400 part-per-billion (by mass) range.

2.
Talanta ; 50(3): 569-76, 1999 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18967746

RESUMEN

The development of liquid chromatography with a commercially available cyano propyl stationary phase and a 100% water mobile phase is reported. Separations were performed at ambient temperature, simplifying instrumental requirements. Excellent separation efficiency using a water mobile phase was achieved, for example N=18 800, or 75 200 m(-1), was obtained for resorcinol, at a retention factor of k'=4.88 (retention time of 9.55 min at 1 ml min(-1) for a 25 cmx4.6 mm i.d. column, packed with 5 mum diameter particles with the cyano propyl stationary phase). A separation via reversed phase liquid chromatography (RP-LC) with a 100% water mobile phase of six phenols and related compounds was compared to a separation of the same compounds by traditional RP-LC, using octadecylsilane (ODS), i.e. C18, bound to silica and an aqueous mobile phase modified with acetonitrile. Nearly identical analysis time was achieved for the separation of six phenols and related compounds using the cyano propyl stationary phase with a 100% water mobile phase, as compared to traditional RP-LC requiring a relatively large fraction of organic solvent modifier in the mobile phase (25% acetonitrile:75% water). Additional understanding of the retention mechanism with the 100% water mobile phase was obtained by relating measured retention factors of aliphatic alcohols, phenols and related compounds, and chlorinated hydrocarbons to their octanol:water partition coefficients. The retention mechanism is found to be consistent with a RP-LC mechanism coupled with an additional retention effect due to residual hydroxyl groups on the cyano propyl stationary phase. Advantages due to a 100% water mobile phase for the chemical analysis of alcohol mixtures and chlorinated hydrocarbons are reported. By placing an absorbance detector in-series and preceding a novel drop interface to a flame ionization detector (FID), selective detection of a separated mixture of phenols and related compounds and aliphatic alcohols is achieved. The compound class of aliphatic alcohols is selectively and sensitively detected by the drop interface/FID, and the phenols and related compounds are selectively and sensitively detected by absorbance detection at 200 nm. The separation and detection of chlorinated hydrocarbons in a water sample matrix further illustrated the advantages of this methodology. The sensitivity and selectivity of the FID signal for the chlorinated hydrocarbons are significantly better than absorbance detection, even at 200 nm. This methodology is well suited to continuous and automated monitoring of water samples. The applicability of samples initially in an organic solvent matrix is explored, since an organic sample matrix may effect retention and efficiency. Separations in acetonitrile and isopropyl alcohol sample matrices compared well to separations with a water sample matrix.

3.
Chiropr Hist ; 15(2): 30-5, 1995 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11613397

RESUMEN

B.J. Palmer was clearly the most colorful of chiropractic's personalities and he exerted a powerful influence over the profession for many years and was perceived in a variety of ways. At the age of 18, his father abandoned the ownership and responsibility for the PSC and the profession was effectively transferred to him. From this point B.J.'s successes and his diplomatic failures evolved simultaneously. B.J.'s near-obsessive reductionistic traits appear to derive from his father's school teacher emphasis on reducing complex systems to simple explanations. B.J. and his father were at odds through life, yet B.J. remained respectful through his adult years until D.D. died in 1913. He was greatly influenced by his father's attitudes and admonitions and by his father's assumption that the Palmer family had a proprietary role in chiropractic.


Asunto(s)
Quiropráctica/historia , Historia del Siglo XIX , Historia del Siglo XX , Estados Unidos
6.
J Trauma ; 17(5): 392-6, 1977 May.
Artículo en Inglés | MEDLINE | ID: mdl-870702

RESUMEN

Post-traumatic cysts of soft tissue, formed by crushing and shearing strains, usually occur at the junction of the subcutaneous fat and deep fascia. They become filled with serosanguinous fluid and lined with fibrous tissue. Chronic cysts may either remain stable or occasionally expand, much like a subdural hematoma.


Asunto(s)
Tejido Adiposo/lesiones , Quistes/etiología , Fascia/lesiones , Heridas no Penetrantes/complicaciones , Adulto , Quistes/cirugía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/cirugía , Heridas no Penetrantes/cirugía
7.
J Oreg Dent Assoc ; 38(4): 15-6, 1968 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-5248632
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