Sensitivity and Responsiveness

4 Thermal Responsiveness versus Hydrophobic Association 4.1 Sensitivity and Responsiveness 

It is worth stressing here that thermal sensitivity is a general phenomenon for polymers in solution the solubility of all polymers in any solvent depends on temperature. For that reason, Allan Hoffman defined intelligent stimuli-responsive polymers as polymers that respond to a small physical or chemical stimulus with large property changes [68-70]. The coil-globule transition is a typical polymer response to a change in its solution temperature. 

The internal energy of the segmental interactions, which represents the excluded volume effect, can be expanded as a power series of the segment density p  

The second osmotic virial coefficient of the expansion, A2, is a measure of the thermodynamic quality of the solvent for the polymer and accounts for binary 

This type of transition is conveniently represented as a phase diagram in which the phase separation boundary, or binodal, indicates the temperature for which a given polymer-solvent mixture passes from a one-phase system to a two-phase system that consists of a polymer-rich phase and a polymer-poor phase. In other words, the binodal corresponds to the temperature at which the coil-globule transition takes place followed by polymer precipitation (see Fig. la). The shared maximum of the 

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Quantitative analysis using the internal standard method. The height and area of chromatographic peaks are affected not only by the amount of sample but also by fluctuations of the carrier gas flow rate, the column and detector temperatures, etc., i.e. by variations of those factors which influence the sensitivity and response of the detector. The effect of such variations can be eliminated by use of the internal standard method in which a known amount of a reference substance is added to the sample to be analysed before injection into the column. The requirements for an effective internal standard (Section 4.5) may be summarised as follows ... 

We scrutinize issues dealing with requirements of high sensitivity and response selectivity of electrophysical parameters in reference to the gas monitored or the type of active particles under study as well as other requirements put forward to adsorbents of chemical sensors. We discuss principles underlying the basis of solving these problems. We dwell on the issue of the type of crystal of adsorbents examined, which is directly linked to the character of intracrystallite contacts. 

The analytical technique of choice for the identification of low molecular weight terpenes and terpenoids is GC/MS, assisted by off-line methylation or silylation reactions. However, comparable results in terms of sensitivity and response specificity... 

A great feature of the proposed configuration is the possibility to select the overlay thickness and mode order to meet specific requirements in terms of sensitivity and response time. In addition, with commercially available and low cost spectrometers, a wavelength shift resolution of 0.05 nm is easily available, allowing sub-ppm chemical detection. 

More modern instrumental analysis has been used to improve sensitivity and response time. Shown in Figure 7 is a schematic diagram of an instrument that has been developed to measure NO and N02 (18). The detection scheme is based on the chemiluminescence produced when NO in the ambient air reacts with 1% ozone added as a reagent to the sampled airstream. 

The regulatory domains of the various receptors overlap, a property that allows different tissues to respond differently to hormonal stimuli. The result is the network of interactions that makes the body so sensitive and responsive. 

Wesnes, K., Warburton, D.M., and Matz, B., Effects of nicotine on stimulus sensitivity and response bias in a visual vigilance task, Neuropsychobiology, 9, 41, 1983. 

Figure 14. Effect of CO on the hydrogen sensitivity and response time of a Pd/Si02 ( vlOOO X)/n-Si capacitor. Device kinetic response to 2% H2/96% N2 at RT. Curve 1, the device is not exposed to 4% CO/96% N2 and initial ambient is 100% O2 curve 2, the device is exposed to 4% CO/96% N2 prior to the initial ambient 100% O2 and curve 3) the initial ambient is 4% CO/96% l. ...

Figure 15. Effect of different I-layer and C-layer on the device sensitivity and response time to a) 1000 PPM H2 in air at 150°C. The device is a Pd/Top I-layer (Si02. AI2, O3, Ta2 O3, Si3 N4)/ Si02/p-Si capacitor and the initial ambient is air (after Ref. 16, 1984 IEEE) and b) 7 PPM, 25 PPM, and 70 PPM NH3 in air at 150 C, device used here is an ultra thin Pt-layer/Pd/Si02/p-Si capacitor (after Ref. 9, with permission).

Any of these steps can be rate limiting, thus determining the ultimate sensitivity and response characteristics of the... 

Controllable film thickness (compromise between sensitivity and response time of the sensor system)... 

The analyte sensitivity and response time of a PVC film can also be markedly improved with addition of plasticizers such as tributyl phosphate (TBP) or tripropyl phosphate (TPP), since it is well established that the presence of plasticizer in the polymer-encapsulating medium increases gas diffusion rate by increasing the degree of polymer segmental mobility. It is... 

With respect to exposures, there are many possible toxicants. More than 100000 chemicals exist (Commission of the European Communities, 1990), the number of possible mixtures is almost infinite, and the exposure of biota to chemicals is influenced by matrix characteristics. With respect to sensitivity and responses of biota, there is great natural variability among species and ecosystem types and in the array of conditions in which they occur. It is evident that an array of extrapolation types is needed for risk assessment. 

Are multiple stressors influencing the sensitivity and responses of the exposed species ... 

The response times of the three kinds of Na+ ISFETs are also within seconds of one another. The above-mentioned characteristics, such as linear response range, sensitivity and response time ate almost the same in PVC, Urushi and KP-13 matrix ISFETs. 

The permeation of He through quartz glass is exploited in He leak detection. Test leaks have many applications including the calibration of MSLD (Section 4.3) and the assessment of the sensitivity and response time of the system. 

Thin films, to attain enough sensitivity and response time, of oxide materials normally deposited on a substrate are typically used as gas sensors, owing to their surface conductivity variation following surface chemisorption [183,184], Surface adsorption on a Sn02 film deposited on alumina produces a sensitive and selective H2S gas sensor [185]. In addition, a number of perovskite-type compounds are being used as gas sensor materials because of their thermal and chemical stabilities. BaTi03, for example, is used as sensor for C02 [183],... 

Signal-Sensitive and Responsive-Controlled Release Systems. 

The official cotton standards of the United States for the grade of Upland cotton are also called the universal standards. Leading cotton associations in major cotton-consuming countries meet periodically to establish a continuing consensus of cotton classification. International conferences are held every 3 years in the United States to consider revisions and to ensure accurate reproduction of the standards. By this method, the U.S. cotton classification system maintains sensitivity and responsiveness to cotton consumer needs. 

Sensitive, selective detection of biochemically active compounds can be achieved by employing antigen-antibody, enzyme-substrate, and other receptor-protein pairs, several of which have been utilized in the development of piezoelectric immunoassay devices. The potential analytical uses of these materials has been reviewed, particularly with respect to the development of biochemical sensors [221-224], The receptor protein (e.g., enzyme, antibody) can be immobilized directly on the sensor surface, or it can be suspended in a suitable film or membrane. An example of the sensitivity and response range that can be... 

White et al. synthesized nanometric La2Cu04 through three techniques auto-ignition, Pechini method, and coprecipitation (White et al., 2008). The NPs were used to fabricate sensing electrodes for NO, and the effect of electrode microstructure on the sensitivity and response time was studied. The response times of the sensors were exponentially dependent on electrode grain size. Sensors with fine-grained electrodes were able to produce a steady-state and consistent voltage at lower temperatures, which improved their response sensitivity. 

Variation in ecosystem sensitivity and response due to hydrologic variabflity can be seen in North Carofina s Pamlico Sound, the US s largest lagoonal ecosystem and second largest estuary (1700 km ), draining numerous sub-estuaries. This system exhibits N limitation from its upstream oligohaline riverine components to the inlets... 

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