New instrumentation

The rotational relaxation of DNA from 1 to 150 ns is due mainly to Brownian torsional (twisting) deformations of the elastic filament. Partial relaxation of the FPA on a 30-ns time scale was observed and qualitatively attributed to torsional deformations already in 1970.(15) However, our quantitative understanding of DNA motions in the 0- to 150-ns time range has come from more accurate time-resolved measurements of the FPA in conjunction with new theory and has developed entirely since 1979. In that year, the first theoretical treatments of FPA relaxation by spontaneous torsional deformations appeared. 16 171 and the first commercial synch-pump dye laser systems were delivered. Experimental confirmation of the predicted FPA decay function and determination of the torsional rigidity of DNA were first reported in 1980.(18) Other labs 19 21" subsequently reported similar results, although their anisotropy formulas were not entirely correct, and they did not so rigorously test the predicted decay function or attempt to fit likely alternatives. The development of new instrumentation, new data analysis techniques, and new theory and their application to different DNAs in various circumstances have continued to advance this field up to the present time. 

Time will tell which new methods will be introduced to the major international pharmacopoeias — USP, EP, and JP. The CE is one of the main candidates to be used more often. One indication is the fact that besides the traditional instrument new manufacturers start to build CE instruments. The resulting competition will animate the market and stimulate the development of new and more effective techniques. 

TA Instruments CSL2 Controlled Stress Rheometer D-E 10 2 -109 10 6-5 x 103 good TA Instruments, New Casde, Del. 

Fig. 1.26. DSC 2920 instrument with DTA measuring cell. This installation is not designed for low temperatures, but can be modified for this purpose (commercial standard installations for low temperatures could not be found by the author) (TA Instruments, New Castle, DE, USA)...

Fig. 1.45.1. Artist s view of a DSC cell in Tzero technology as used in modulated DSC (MDSC) processes. 1, Sample and reference table made from one piece of constantan 2, chromel thermocouples directly connected to the constantan tables 3, Tzero sensor from chromel-constantan in the middle between sample and reference table (TA Instruments, New Castle, DE, USA...

Wolfram, L.J., in Leveque, J.-L., (ed.), Cutaneous Investigation in Health and Disease Noninvasive Methods and Instrumentation, New York, Marcel Dekker, 1989, Ch 3. 

Figure 4 Differential scanning calorimetry endotherms (DSC model 2910, TA Instruments, New Castle, DE) of cowpea protein-corn starch blends in different ratios (R) at pH 7 and scanning rate 5°C min-1. (Courtesy of Okechukwu and Rao, 1996b.)...

Control measurements of the monolayer include measurements of transepithelial resistance with an Endohm Meter (World Precision Instruments, New Haven) and permeability measurements of mannitol and polyethylenglycol 4000 (marker for low... 

Drags are tested at 10 p,M concentration and in two directions (apical to basolateral (a-b) and basolateral to apical (b-a)). Monolayer efflux studies are conducted at 37 °C in a humidified incubator with shaking (90 rpm) for 60 min. Transendothelial electrical resistance is measured with an Endohm Meter (World Precision Instruments, New Haven, CT). Reference drags for paracellular transport (14C-mannitol), tran-scellular transport (3H-propranolol), and Pgp efflux (amprenavir) should be included in each experiment. Concentrations of 14C-mannitol and 3H-propranolol are measured by liquid scintiallation counting. Amprenavir is analyzed by cassette LC/MS/MS analysis along with the test drags. 

The total fixed-capital investment for the installed equipment may be obtained by multiplying the cost of all the primary and accessory equipment by 4. This factor takes care of construction costs and all other fixed costs such as piping, valves, instrumentation, new buildings, etc. (This, of course, does not include the original solvent cost or any raw materials.)... 

MDSC, developed by TA instruments (New Castle, Detroit, U.S.A.), is based on the conventional heat flux DSC furnace design. The temperature programs differ... 

SP Perone. In JS Mattson, H6 Mark Jr, HC MacDonald Jr, eds. Electrochemistry Calculations, Simulation and Instrumentation, New York Dekker, 1972, Chap 13. 

The flow curves can be established for different concentrations and different molar masses of HA samples, and at different temperatures for a better insight into the molecular properties of polymers. Fig. (14) shows results of a series of rheological tests of HA polymers with different molar masses at different concentrations. Fig. (14, left panel) shows the flow curves for three different HA samples with the Mw values of 850 kDa, 600 kDa, and 400 kDa. Fig. (14, right panel) exhibits the flow curves for an HA sample at four different concentrations ranging from 0.11% to 2.16%. The flow curves are obtained by using an AR 2000 stress-controlled rheometer from TA Instruments (New Castle, DE, USA). A cone/plate geometry is used. The rotor was made of the acrylic material, 4 cm of diameter and 1° of cone angle. The measurements were performed at 20 °C. 

Meyers, Robert A. Encyclopedia of Analytical Chemistry Applications, Theory, and Instrumentation. New York Wiley, 2000. 

Karnilc HB. Laboratory instruments in chnical chemistry, principles of. In Meyers RA, ed. Encyclopedia of analytical chemistry Applications, theory, and instrumentation. New York John Wiley Sons, 2000 1395-410. 

Differential scanning calorimetry Samples of gels (8 to 11 mg) were placed in hermetically sealed stainless steal pans and analyzed with a DSC QlOO (TA Instruments, New Castle, DE, USA). An empty pan was used as reference. Samples were heated at 10°C/min from -40 to 120°C. At least triplicate samples were analyzed for each gel. The endothermic melting peak around 0°C was taken as an evidence of ice melting. Endothermic peaks in the 50 to 70°C range were taken as evidence of starch retrogradation (stored samples). 

For DSC analysis, samples of about 10 mg conditioned in hermetic TA aluminum pans were heated at 10°C/min, between —120 and 100°C, in inert atmosphere (45 ml/min of N2) in a DSC TA2010 controlled by a TA5000 module (TA Instruments, New Castle, DE). The reference was an empty... 

FIGURE 10.10 Diagrammatic representation of the design of the dynamic mechanical analyzer 2980. (Adapted from Dynamic Mechanical Analyser 2980 Operator s Manual, TA Instruments, New Castle, DE, 1996.)... 

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