bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption of collagenase to particulate titanium: A possible mechanism for collagenase localization in periprosthetic tissue
Authors: Kane Kevin R. , DeHeer David H. , Owens Scott R. , Beebe John D. , Swanson Alfred B. 
Published: May 2005

AbstractOsteolysis is a central feature of aseptic loosening of orthopaedic joint prostheses. This destructive process is believed to result from phagocytosis of implant wear debris by periprosthetic and synovial macrophages and the subsequent release of proinflammatory mediators, including collagenase. Isolated murine macrophages were cultured in vitro with particulate titanium in order to explore the mechanism of macrophage activation by particulate wear debris. The results, in which the amount of secreted, soluble collagenase in culture supernatants was inversely proportional to titanium concentration, suggested that titanium strongly adsorbed secreted collagenase. This inference was confirmed by direct binding assays in which particulate titanium coated with adsorbed collagenase bound an alkaline phosphatase conjugated anticollagenase antibody, but not a conjugated anti‐IgG antibody. Adsorption of collagenase was not influenced by preincubation of titanium particles with albumin. The adsorbed collagenase remained enzymatically active as indicated by its ability to hydrolyze a synthetic peptide substrate. These results demonstrate that particulate titanium stimulates collagenase production by macrophages and then strongly adsorbs the secreted proinflammatory enzyme. The process of macrophage stimulation, collagenase secretion, and adsorption may represent an important mechanism for localization and concentration of collagenase in periprosthetic and synovial tissue, a mechanism that ultimately triggers bone resorption through osteoclast activation. © 1994 John Wiley & Sons, Inc.
Histological and mechanical comparison of hydroxyapatite‐coated cobalt‐chrome and titanium implants in the rabbit femur
Authors: Friedman Richard J. , Bauer Thomas W. , Garg Kamil , Jiang Ming , An Yuehuei H. , Draughn Robert A. 
Published: May 2005

AbstractThe purpose of this study was to compare hydroxyapatite (HA)‐coated titanium (Ti) and HA‐coated cobalt‐chrome (CoCr) implants in the distal femur of the rabbit by evaluating bone apposition and interfacial shear strength. Bilateral cylindrical implants with a plasma sprayed 50‐m̈m thick HA coating were press‐fit into the metaphyseal cancellous bone of the lateral femoral condyles in a transverse fashion, and the animals were sacrificed at 2, 4, and 8 weeks postimplantation. Mechanical strength of the interface between HA and bone was measured using the pushout method. For histologic analysis, the fractional linear extent of bone apposition was quantitated. No differences were found in the interfacial shear strength between the Ti and CoCr at any time period. The amount of bone apposition increased significantly at each time interval for both substrate metals, but there were no significant differences between the two substrates at any of the time periods studied. The HA‐coated CoCr implants performed in a similar manner to the HA‐coated Ti implants, both mechanically and histologically, suggesting that HA‐coated CoCr implants deserve further study as a viable alternative to Ti for the biological fixation of total joint components in orthopaedic surgery. © 1995 John Wiley & Sons, Inc.
Practical aspects of Pt/Ir effluent splitters for multidetector GC and pneumatic solute switching
Authors: Anderson E. L. , Bertsch W. 
Published: May 2005

AbstractPractical details are given to produce low dead volume Pt/Ir to glass connections and a variety of components for effluent splitting and pneumatic solute switching. It is shown that the column effluents from a glass capillary column can be split in any desired ratio and maintained constant, regardless of column flow rate. Bandbroadening in the splitter remains negligible even for very low flow rates. A complex pneumatic system to be used for heartcutting with two glass capillary columns is shown.
Whisker surfaces in (GC)2
Authors: Sandra P. , Verstappe M. , Verzele M. 
Published: May 2005

AbstractGrowing whiskers on the inner wall of glass capillary columns is an easy roughening technique which allows efficient coating of the columns with any stationary phase. The advantages and disadvantages of whisker surfaces are discussed. Several examples are presented to illustrate the possibilities of whisker‐wall coated open tubular (WWCOT) columns.
Interpretation of the real plate number concept: A fundamental analysis
Authors: Smuts T. W. , Buys T. S. , de Clerk K. , du Tolt T. G. 
Published: May 2005

AbstractThe real plate number concept is interpreted in terms of the fundamental properties of a chromatograph. It is shown that the linear relationship between the total peak width at half height, (b0.5)T, t, and k is only an approximation of the more general linear relationship between (b0.5)2T, t and (1 + k)2. In the case where the relationship between (b0.5)T, t and k approaches linearity, it is concluded, firstly, that b0 = a, i. e., b0 is a column property and independent of extra‐column phenomena and, secondly, that nreal=ntheor. When the relationship becomes non‐linear, b0 is determined partly by extra‐column phenomena, but not in terms of a useful relationship. It is concluded that it is unnecessary to introduce the parameters a, b0 and nreal, since they all have counterparts in the established theory of chromatography. These counterparts prove to be equally useful in the practical analysis of chromatographic systems.
Analysis of volatile fatty acids by gas chromatography separation of benzyl esters
Authors: Liardon Rémy , Kühn Ursula 
Published: May 2005

AbstractVolatile fatty acids in aqueous media were esterfied in situ with phenyldiazomethane (PDM). Complete esterification was achieved in 3 h at 40°C under continuous stirring of an ether/water system. The process involved immediate transfer of benzyl esters into the organic phase. The separation of benzyl esters mixtures was carried out in glass capillary GC columns. The retention data and FID molar responses were determined for C1 to C6 acid benzyl esters, including 2‐methylpropionic, 3‐methylbutyric, 2‐methylvaleric, and 2‐ethylbutyric acid. An unusual relationship was observed between benzyl ester relative molar responses and carbon atom number.
Preparation of apolar glass capillary columns by the barium carbonate procedure
Authors: Grob K. , Grob G. , Grob K. 
Published: May 2005

AbstractAs an extension of previous reports, the barium carbonate procedure has been optimized in detail for the preparation of apolar columns. The aim was to produce optimum overall column characteristics, and to maintain them unchanged under the prolonged influence of the highest possible temperature. The main parameters under optimization were glass variety, leaching of glass surface with aqueous HCl, and amount of barium carbonate deposited, while deactivation and coating were kept constant. The basic column characteristics were adsorption properties and thermostability of deactivation, acid/base behaviour and separation efficiency. They were determined by a new, quantitative testing procedure. Intense leaching was able to eliminate almost totally the differences between glass varieties and to create a well‐defined glass surface. While untreated glass, leached glass, and barium carbonate treated glass showed specific weak points in the respective column quality, the combination of leaching and barium carbonate treatment yielded the highest and most stable quality. Some technical modifications of the preparation procedure are described, including deactivation in the gas phase, and use of pentane as a solvent for static coating.
Surface modified wall coated open tubular columns: Development and application in pesticide analysis
Authors: Onuska F. I. , Comba M. E. 
Published: May 2005

AbstractFilamentary crystal growth on the inner surface of a glass analytical capillary column using a modified ammonium hydrogen difiuoride procedure, produced highly efficient wall coated open tubular columns.Baseline separation of the acetate derivatives of 2,3,4,6‐ and 2,3,5,6‐tetrachlorophenol was achieved and was instrumental in determining pentachlorophenol loadings along a watershed. The application of capillary columns, related to the analyses of organochlorine pesticide residues is also demonstrated. Parent and degradation products of twenty‐five commonly monitored residues were effectively resolved on a 20 MOV‐101 column.
Continuous TLC as a pilot technique for optimization of gradient HPLC. 1. Theoretical considerations for stepwise gradient TLC with binary mobile phase
Authors: Golkiewicz W. , Jaroniec M. 
Published: May 2005

AbstractEquations describing gradient elution in TLC, with a mobile phase of a constant composition in each step, have been derived. These equations are useful for calculating retention volumes from isocratic TLC data. Equations originally derived for gradient HPLC were adapted for TLC. The validity of the equations has been experimentally verified. The satisfactory agreement between experiment and theory for binary mobile phase composed of methyl ethyl ketone and n‐heptane suggests that TLC can be used as a pilot technique for gradient HPLC.
The HPTLC separation of malondialdehyde from peroxidised linoleic acid
Authors: Gutteridge J. M. C. 
Published: May 2005

AbstractPeroxidised linoleic acid reacts with acidified thiobarbituric acid to give a chromogen absorbing maximally at 532 nm. This TBA reactant is chromatographically identical to the TBA‐MDA adduct formed from linolenic acid and a pure MDA standard. Considerably less MDA is produced by peroxidised linoleic acid compared to that formed from linolenic acid. In this respect the type of acid used for the colour reaction appears to be important.
A simple terminator for high efficiency liquid chromatography columns
Authors: Heath R. R. , Proveaux A. T. , Tumlinson J. H. 
Published: May 2005

AbstractA comparison is made between a flat bottom column terminator and a cone terminator on. 1.27 cm O.D. and 2.54 cm O.D. columns. The cone terminator results in a doubling of the column efficiency, is simple and inexpensive, and is universally adaptable to any diameter column.
Analysis of polynuclear aromatic hydrocarbons by glass capillary gas chromatography using simultaneous flame ionization and electron capture detection
Authors: Bjorseth Alf , Eklund GÖRan 
Published: May 2005

AbstractThe possibility of simultaneous application of an electron capture (ECD) and a flame ionization detector (FID) connected to a glass capillary column for analyzing polynuclear aromatic hydrocarbons (PNA) has been investigated. The ECD/FID ratio is determined for 46 PNA compounds. The ratios vary from 0.02 to 117 with relative standard deviations better than 20 percent determined from 10 replicate analyses. The results suggest that the method may be used for obtaining additional evidence in identifying PNA in environmental samples.Impurities and transformation products in the standard were identified by computerized glass capillary gas chromatography/mass spectrometry. Quinones and diones are responsible for the high EC‐response determined in some trace components in the standard.An application of the method is shown for PNA from particulates in urban atmospheres.
Thermodynamic interactions of polypropylene, poly(vinylidene chloride), sulphonyldiphenyl formaldehyde resin and poly(vinyl pyrrolidone) as stationary phases in GLC with some selected solvents
Authors: Abushihada A. M. , Shunbo F. E. , Al‐Sultan Y. Y. 
Published: May 2005

AbstractThe interaction energies (X1) between the polymers polypropylene, poly(vinylidene chloride), sulphonyldiphenyl formaldehyde resin and poly(vinyl pyrrolidone) and the solvents toluene, ethylbenzene, isopropylbenzene, ortho, meta, and para‐xylene are determined by gas chromatography. As shown in earlier publications, this technique for the determination of X1, can be extended to similar systems of theoretical as well as of practical importance, although the selection of the present systems was primarly made on the fact that these systems are of industrial interest and have not so far been investigated by gas‐liquid chromatography. The studies were carried out at two temperatures and the results obtained show a decrease of X1 with an increase of temperature.
Determination of the 7‐amino‐metabolites of the 7‐nitro‐benzodiazepines in human plasma by thin‐layer chromatography
Authors: Haefelfinger P. 
Published: May 2005

AbstractA sensitive thin‐layer chromatographic method is described for the determination of the 7–amino‐metabolites of flunitrazepam and clonazepam. The same procedure is applicable to other 7‐nitro‐benzodiazepines such as nitrazepam. A purified plasma extract of the 7‐amino‐metabolites is separated by thin‐layer chromatography. The primary aromatic amines are diazotized and coupled with N‐(1‐naphthyl) ethylene‐diamine on the thin‐layer plate. The quantities of the 7‐amino‐metabolites are directly evaluated by colorimetric densitometry. The lower limit of detection is in order of 0.5–10 ng cm−3 of plasma. The relative standard deviation of the whole procedure is less than ±15% in the range of 0.5–10 ng cm−3 for a single determination.The unchanged drugs can be reduced on the thin‐layer plate and detected by the same method. Since this procedure is rather difficult to perform, it is advantageous to determine the 7‐nitro‐benzodiazepines in plasma by gas chromatography.The thin‐layer chromatographic method was used to measure the 7‐amino‐metabolites in plasma of patients on either a flunitrazepam or a clonazepam oral dosing regimen.
The application of flow switching rotary valves in two‐dimensional high resolution gas chromatography
Authors: Miller Roger J. , Stearns S. D. , Freeman R. R. 
Published: May 2005

AbstractTwo‐dimensional high resolution gas chromatography with small bore glass capillary columns is simplified by use of a single 6–port flow switching rotary valve. The band spreading and tailing normally associated with mechanical valves is overcome by matching the internal valve passage diameters to that of the capillary column, and by minimizing unswept volumes in the fittings. selection of inert valve and transfer line materials effectively ellminates undesirable adsorption phenomena. The high thermal stability of the value permmits it to be mounted directly in the GC oven where it can be actuated externally. With slight modifications either packed or capillary pre‐columns may be used for initial saperations. Application of enrichment, solvent removal and heart cutting are described.
Comparison of log k′ — solvent composition relationships in thinlayer and column chromatography for systems of the type: Silanized silica — water + methanol
Authors: Dzido T. , Soczewiński E. 
Published: May 2005

AbstractRelationships between log k' values of polynuclear hydrocarbons and composition of water/methanol mixtures were determined for HPTLC on RP‐18 silica and for HPLC using RP‐2 silica. In spite of differences in the adsorbents used, a good correlation between HPLC and TLC parameters was found. In the TLC experiments, a sandwich tank with a modified solvent distributor was used.It has been reported that thin‐layer chromatography is a good technique for the preliminary optimization of column chromatographic separations [1–5]. So far, the comparison of TLC and HPLC has been mainly restricted to silica as the adsorbent. Since TLC plates precoated with silanized adsorbents recently became commercially available, it seemed interesting to compare the chromatographic parameters obtained for the “reversed phase” systems with the two techniques (see also ref. 6).
The assay of antibiotics in pharmaceutical preparations using reverse‐phase HPLC
Authors: Bagon Kay R. 
Published: May 2005

AbstractChromatographic methods are presented for the determination of chloramphenicol, erythromycin, tyrothricin, nystatin, penicillin, streptomycin, sulphanilamides and nitrofurans, in some pharmaceutical formulations. The methods have been applied in routine analysis and are in general capable of distinguishing the main antibiotic from decomposition products and likely congeners.
A sampling system using sample vials for high‐temperature isothermal capillary gas chromatography
Authors: Evrard E. , Mercier M. , Bal M. 
Published: May 2005

AbstractA novel sampling system for isothermal capillary gas chromatography of medium‐ or low‐volatility mixtures is described and test results are reported using flame ionization detection. The system features a loading and positioning chamber for glass vials which can carry a dilute sample in up to 0.2 ml of a volatile solvent. The output from the glass vaporization chamber is trapped onto a packed precolumn operated in the backflush mode. The analytes are further transferred over a wall‐coated capillary trap prior to isothermal capillary GLC. Repeat‐cycle operation of the sampling system requires 10 channels of a processor for time control over 5 solenoid valves and 3 static heaters. Preliminary results with long‐chain n‐alkanes in the submicrogram range showed no unwanted effects. The principal claim of the system is an improved rejection of non‐volatiles.
Vapor‐phase sampling
Authors: Jennings W. G. 
Published: May 2005

AbstractTwo new sample preparation procedures that produce solvent‐free extracts especially suitable for use with high resolution GC are described. One is based on Soxhlet extraction in a pressurized container that permits the use of liquid carbon dioxide as the extractant; the other utilizes refluxing difluorodichloro‐methane (Freon 12) to isolate entrained volatiles from gas streams.
A versatile all‐glass GC/MS interface for capillary columns
Authors: Schmid P. P. , Müller M. D. , Simon W. 
Published: May 2005

AbstractA new all‐glass interface for GC/MS designed to fully exploit the potential of glass capillary columns is described. The system works in the open split mode and has high versatility with respect to column changing. It is especially suitable for mass spectrometers, which are not exclusively dedicated to GC/MS work. Two chromatograms illustrate the properties of the described interface.
Superoxes, high temperature universal phases in (GC)2
Authors: Sandra P. , Verzele M. , Verstappe M. , Verzele J. 
Published: May 2005

AbstractMost of the common classes of organic compounds chromatograph normally on Superoxes. There is no tailing or adverse effect from excessively different activity different activity coefficients. Superoxes are therefore universal phases for gas chromatography. This is also expressed by a wide useful temperature range from ∼50° to ∼300°. High MW Superox‐4 has a MAOT about 20° higher than the lower MW Superox‐0.1. Several applications illustrating the versatility of Superox phases in (GC)2 are presented.
Advances in the preparation and evaluation of GC capillary columns
Authors: Verzele M. , Sandra P. 
Published: May 2005

AbstractThe preparation of (glass) capillary columns of high quality is still not without difficulties. Six problems in this context are highlighted. Column material choice(l), glass wall modification(2) and coating(3) are considered to have reached a satisfactory level. Deactivation(4) is still in a state of flux. Quantitation(5) is the least satisfactory aspect of capillary GC. Scope expansion(6) will be helped by the introduction of new phases of high thermal stability and by the adoption of solutions exclusively applicable to capillary GC.Evaluation of (glass) capillary GC columns is a rapidly developing field. Hopefully the number and complexity of test or polarity mixtures will not expand much further and it will be possible to make a clear and generally acceptable choice.The preparation and evaluation of ever‐improving capillary columns is important to an ever‐widening group of chromatographers. Our opinion on selected topics in this already vast field is summarized in the following overview.
Theory of GC2 — an unusual approach
Authors: Franzen J. 
Published: May 2005

AbstractIn contrast to traditional theoretical approaches by calculation of (nonexistent) theoretical plates, a unified theory of gas chromatography as given by a definition of the resolution analogue to methods in signal processing or spectroscopy using the well‐known Kovacz indices as fundamental scale. A derivation of the thusly defined resolution from basic physical principles yields very practical formulae for peak width, maximum load, substance flow in peak maximum, concentration of substance in the carrier gas and other interesting parameters in dependence of capillary diameter, capillary length, film thickness, carrier gas speed, viscosities etc. Diagrams show favourite conditions for detectors responding on absolute substance flow (e.g. FID) or on concentrations.
Special cooling system for the on‐column injector in capillary gas chromatography eliminating discrimination of sample compounds
Authors: Galli M. , Trestianu S. , Grob K. 
Published: May 2005

AbstractOn‐column injection into a hot gas chromatograph oven involves the danger that the bottom part of the needle is warmed up above the boiling point of the solvent in the sample. Consequently parts of the sample are evaporated out of the needle instead of being introduced as a liquid into the capillary column. This causes losses and hence discrimination of the less volatile parts of the sample which remain in the needle.A technical solution is proposed using a system for cooling the capillary during the injection, down to the injection point in the oven.
A novel method of preparing of glass capillary columns: Low‐temperature plasma etching and polymerization
Authors: Masada Y. , Hashimoto K. , Inoue T. , Sumida Y. , Kishi T. , Suwa Y. 
Published: May 2005

AbstractA novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low‐temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC2). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification.
Stationary phases for gas chromatography; chemical stability of polysiloxanes
Authors: Venema A. , Ven L. G. J. v. d. , Steege H. v. d. 
Published: May 2005

AbstractA number of polysiloxanes have been shown to be sensitive to acids when dissolved in chloroform.At 26O°C polysiloxanes were found to degrade under the influence of several compounds used or produced during the preparation of glass capillary columns.
Profiles of volatile metabolites in biological fluids using capillary columns
Authors: Zlatkis A. , Poole C. F. , Brazell R. , Lee K. Y. , Singhawangcha S. 
Published: May 2005

AbstractNickel capillary columns coated with moderately polarstationary phases such as Witconol can be used for the separation of the organic volatile fraction from biological fluids. A “transevaporator” sampling technique for the collection of the organic volatiles on glass beads from as little as 5 to 500 μl of biological fluids (e.g. urine, serum, amniotic fluid, breast milk, saliva, etc.) is described. The organic volatiles are thermally desorbed from the glass beads into a short precolumn cooled in liquid nitrogen, which overcomes the problems associated with sample introduction onto narrow‐bore capillary columns. The application of the full analytical technique to problems associated with the early detection of disease is illustrated.