Contact experiments

We used modifications of the standard solid-state CP-MAS (cross-polarisation, magic-angle spinning) experiment to allow the proton relaxation characteristics to be measured for each peak in the C spectrum. It is known that highly mobile, hydrated polymers can not be seen using either usual CP-MAS C spectrum or solution NMR (6). We found, however, that by a combination of a long-contact experiment and a delayed-contact experiment we could reconstruct a C spectrum of the cell-wall components that are normally too mobile to be visible. With these techniques we were able to determine the mobility of pectins and their approximate spatial location in comparison to cellulose. 

In the delayed-contact experiment a variable delay, during which proton spin-locking was maintained, was inserted prior to a fixed contact time of 0.5 ms. 

So that the results from the delayed-contact and variable-contact data could be compared, they were normalized to give equal signal intensities at a contact time of 0.5 ms (zero delay in the delayed-contact experiment) after the variable-contact data had been adjusted to allow for the fact that full equilibration of proton and polarisation had not quite been reached after 0.5 ms. The difference in normalised signal intensity between the variable-contact and delayed-contact experiments, at a given time point t, is then a measure of the amount of 13C cross-polarising between 0.5 ms and t. 

Unlike control females, chemically naive females do not prefer the volatile components of male odors compared to female odors. When these females are allowed contact with the odors, however, they demonstrate robust preferences for the male odors. Critically, initially naive females that receive contact experience with male soiled bedding as adults display sexual odor preferences when subsequently... 

Although chemically-naive female hamsters prefer to investigate volatile male odors, early contact experience with male odors is required for the differential expression of vaginal marking in response to male and female volatile odors. Whereas control females vaginal mark more to male odors than to female odors, chemically naive females mark equally to the volatile components of these two odor sources. This lack of differential marking by naive females is primarily due... 

If a vaccinated or unvaccinated contact experiences a fever >101° F (38° C) during the 17-day period after his or her last exposure to a smallpox patient, the contact should be isolated immediately to prevent contact with nonvaccinated or nonimmune persons until smallpox can be ruled out by clinical or laboratory examination. 

Fig. 11. Refrigerant-22 water contact experiments. Homogeneous nucleation temperature of R-22 54°C. Interface temperature is 54°C when bulk water temperature 76°C. (O) Armstrong ( ) Board, saturated R-22 (0) Board, 116°C R-22 (A), Armstrong, 68°C R-22 (A) Henry, saturated R-22. [From Anderson and Armstrong (1977).]...

REPEAT CONTACT EXPERIMENTS AT CONSTANT REACTION PARAMETERS RESULTS AND TRENDS... 

Summary of Product Distribution for Repeat Contact Experiments at... 

REFEAT CONTACT EXPERIMENTS UNDER VARIOUS REACTION PARAMETERS. 

Sulphur analysis of the liquids and analyses of the used catalysts revealed the same type of trends as are expounded fortiie experiments at 400 C. Therefore, for all of the repeat contact experiments, irrespective of catalyst or experimental condition, constant catalyst activity was achieved after a single contact so that results from single contacts in autoclaves of the design used in this investigation would be representative of steady state liquefaction conditions, enabling the autoclaves to be used for the rapid accumulation of liquefaction data. 

As in Sect. 2, another experiment is required to evaluate all the diffusivities, i.e., to obtain the correct value for Deiam for use with Table 2. Bai and Miller [4] repeated the contacting experiment of Fig. 13 except that only a thin layer of AOT was present initially. As a result, the similarity solution, which assumes a semi-infinite AOT phase, is not valid after a short transient. Instead the governing equations must be solved numerically with the boundary... 

Figures 10, 11 and 12 show the results of the contact experiments for the basalt, shale and quartz monzonite samples. The rate of adsorption was rapid during the first two weeks and changed slowly thereafter. In these experiments Pu, Am and Cm exhibited behavior similar to the results obtained in the blank experiments. Uranium showed moderate adsorption ( 50 percent) on the basalt but only slight adsorption (10-20 percent) on the shale and quartz monzonite wafers. Neptunium showed strong adsorption (70-80 percent) on the shale and slight adsorption ( v 10 percent) on the basalt and quartz monzonite.

Suppose two systems K pi x) and KB(y) to be in mutual diathermic contact Experience shows that the states SJ and fp, cannot be assigned arbitrarily. 

Only for larger fields exceeding 10 V in reversed polarization direction will mobile surface charges contribute to the overall signal SAC in pfm (deposited upon switching). In contact experiments, however, such mobile charges are directly eliminated via the conductive tip. 

The ferrous porphyrins were reoxidized by introducing oxygen into the NMR tube of the autoreduced sample. To detect water as a product of the reoxidation of TPPFen(CN)22", it was necessary to completely exclude the possibility of atmospheric contact (dry DMSO rapidly absorbs water from the atmosphere). These experiments were done in an NMR tube fitted with a ground glass stopcock. This allowed the addition of oxygen into the NMR tube by vacuum line techniques, completely eliminating atmospheric contact. Experiments done on blanks of dry DMSO showed no water peak. 

Hence in a single contact experiment the gain in signal intensity is approximately... 

Respiratory sensitization to chemicals may be acquired via dermal contact. I26l An example of this is the induction of airway sensitization in workers in a herbicide-producing plant that manufactured 3-amino-5-mercapto-l,2,4-triazole (AMT) by dermal contact. Experiments with mice confirmed the sensitization potential of AMT)27 ... 

Attached to the microscope by a C-mount adapter is a video camera (RCA TC-1000L). A 9-inch video monitor (Panasonic) is used for real-time viewing of contacting experiments. Recording of certain phenomena for later observation is made with a reel-to-reel video recorder (SONY AV-3600). 

Procedure. Rectangular glass capillaries (Vitro-Dynamics) were used as sample cells In the contacting experiments. Their shape prevented optical distortion due to curved surfaces. The capillaries were 50 mm in length and 2 mm in width. Various thicknesses are available, hut 200-micron pathwidth capillaries were found to be best suited for overall observation of interfaces. These were also thick enough to allow discrimination of weak birefringence in the samples. 

Properties of Systems Studied. Contacting experiments at ambient conditions(23 4°C)wereperformed with two commercial petroleum sulfonate systems. The preparation procedure for the aqueous solutions is described elsewhere (5). 

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