Striking phenomenon

Perhaps the most striking phenomenon encountered in outer space is the wide variation in temperature that can be experienced on spacecraft surfaces and externally located equipment. Temperatures and temperature gradients not ordinarily encountered in the operation of ground or airborne structures and equipment are ambient conditions for spacecraft equipment. On such hardware, not suitably protected externally or housed deep within the space vehicle in a controlled environment, these temperature extremes can wreak destruction. Designers of earthbound... 

A mechanical system, typified by a pendulum, can oscillate around a position of final equilibrium. Chemical systems cannot do so, because of the fundamental law of thermodynamics that at all times AG > 0 when the system is not at equilibrium. There is nonetheless the occasional chemical system in which intermediates oscillate in concentration during the course of the reaction. Products, too, are formed at oscillating rates. This striking phenomenon of oscillatory behavior can be shown to occur when there are dual sets of solutions to the steady-state equations. The full mathematical treatment of this phenomenon and of instability will not be given, but a simplified version will be presented. With two sets of steady-state concentrations for the intermediates, no sooner is one set established than the consequent other changes cause the system to pass quickly to the other set, and vice versa. In effect, this establishes a chemical feedback loop. 

PIV velocity measurements made it possible to evaluate the flame temperature field [23], following the method demonstrated in Ref. [25]. The calculated thermal structure of lean limit methane flame is shown in Figure 3.1.7. The differences between the structures of lean limit methane and propane flames are fundamental. The most striking phenomenon seen from Figure 3.1.7 is the low temperature in the stagnation zone (the calculated temperatures near the tube axis seem unrealistically low, probably due to very low gas velocities in the stagnation core). 

A striking phenomenon which probably involves biochemical individuality is that of pathological intoxication. Occasionally an individual, who may be a habitual drinker or not, is afflicted. In a typical case the individual goes berserk and may commit all sorts of crimes and cause damage to property. After a subsequent long sleep he has no memory of his acts.9 This very special type of drunkenness is not caused by any special type of alcohol or necessarily by large amounts it fortunately happens only rarely, and involves only a few individuals. Whether certain individuals are peculiarly susceptible and have repeated typical attacks (these would be classed, no doubt, as alcoholic psychotics) is not clear in any event only certain rare individuals ever are in such a condition as to be susceptible. 

UPD of Cu on Au(lll) electrodes in the presence of sulfate anions has been particularly intensively studied, both experimentally and theoretically [397] (for the review covering the literature up to 1995, see Ref. 398). Sulfate ions are specifically coadsorbed with underpotentially deposited Cu at negative potentials. For this system, a very striking phenomenon is the appearance of two voltammetric peaks, separated by 50-150 mV, upon addition of Cu " " ions to the H2SO4 solution [382, 397, 399-401]. For the potential range separating the peaks, the existence of adsorbate layer of the (. 3 x. 3) structure. 

Various reduced phosphate glasses show striking phenomenon. 

Reduced phosphate glasses of which as-cast glasses are transparent and colorless become tinged with red to yellow depending on the reheating time and temperature. This "striking phenomenon" is due to the formation of colloidal red phosphorus (1). 

If a solution containing approximately 4 mole percent sodium in ammonia is cooled below -42°C (231 K) a remarkable liquid-liquid phase separation occurs (33, 155). The solution physically separates into two distinct layers—a low-density, bronze metallic phase that floats out on top of a more dense, less concentrated dark-blue phase. The first experimental observation of this striking phenomenon in sodium-ammonia solutions was made by Kraus (109, 110) in 1907 more recent studies have mapped out the phase coexistence curves for a variety of alkali and alkaline earth metals in liquid ammonia, and these are delineated and discussed elsewhere (164). 

In the flow of molten polymers through capillaries and other dies, a striking phenomenon is observed of shear stresses at the wall of the order of 105 N/m2. As the flow rate is increased, there is a critical stress level at and above which the emerging polymer stream exhibits irregular distortion. This distortion contributes evidence for some irregularity or resistability in flow. 

The very striking phenomenon of surface migration during condensation is presumably due to the molecules striking the surface with considerable kinetic energy, so that they take some time to settle down into thermal equilibrium with the underlying solid, the oscillations of the atoms when... 

The emission of visible light from a chemical reaction or by a living organism is a striking phenomenon and a rather remarkable occurrence. Perhaps stimulated initially by the mere peculiarity and uniqueness of such events, interest in bioluminescent and chemiluminescent reactions has grown and diversified significantly over the past several decades. Today the reasons for interest in chemiluminescent and bioluminescent systems are remarkably varied, and the field is quite interdisciplinary. 

The MIF phenomenon was first observed by Clayton in 1973 for the isotopic oxygen content in the earliest solids in the solar system, the so-called calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondritic meteorites [1]. The slope of versus plot for the CAIs was close to unity, the CAIs being equally deficient in the heavy O isotopes, deficient in the S notation sense, while the ozone is equally enriched in those isotopes in that sense, as in Figure 2.2. Both are examples of an MIF. Interest in this striking phenomenon for the CAIs is motivated by what it may reveal about the formation of the early solar system. Standard reaction rate transition state theory [3], and behavior of oxygen an other isotope fractionation in many other systems, would have led, instead, to the slope... 

Experimentally, the cholesteric structure parameters, i.e., pitch and handedness, can be derived from the optical properties of the phase and very specially from its so-called selective reflection. This most striking phenomenon is the reflection of one component of circular polarized radiation in a spectral interval around that wavelength which within the medium matches the cholesteric pitch, i.e. XrIh = i when n denotes the... 

In all of these cyanogen compounds we have this striking phenomenon of the probable existence of tautomeric forms in equilibrium. In some cases, as in the acids and the metal salts, the conditions of equi-... 

A striking phenomenon is the intermittent wavelike nature of these effects which affects mood. 

The most striking phenomenon in this series of ethers is the high quantum yield of molecular decomposition in the case of di-t-butyl ether (iji = 0.8 = 80%). Usually, the molecular processes do not exceed 20 percent. This difference has been considered to reflect the strain already present in the ground state of the di-t-butyl ether molecule. 

To demonstrate this effect, we present in the following NCS and electron-proton scattering (ECS) results from various materials, which reveal the following striking phenomenon [Chatzidimitriou-Dreismann 1997 (a) Chatzidimitriou-Dreismann 2003 (a) Physics Today 2003 Scientific American 2003] ... 

The most striking phenomenon in the steady flow of LCPs is the occurrence of a negative first normal stress difference (Ni)—two sign changes in Ni as a function of shear rate. In contrast, isotropic solutions only exhibit positive Ni at all shear rates. Negative Ni has been reported in HPC/H20 and HPC/m-cresol systems. ... 

Perhaps the most striking property of a microemulsion in equilibrium with an excess phase is the very low interfacial tension between the macroscopic phases. In the case where the microemulsion coexists simultaneously with a water-rich and an oil-rich excess phase, the interfacial tension between the latter two phases becomes ultra-low [70,71 ]. This striking phenomenon is related to the formation and properties of the amphiphilic film within the microemulsion. Within this internal amphiphilic film the surfactant molecules optimise the area occupied until lateral interaction and screening of the direct water-oil contact is minimised [2, 42, 72]. Needless to say that low interfacial tensions play a major role in the use of micro emulsions in technical applications [73] as, e.g. in enhanced oil recovery (see Section 10.2 in Chapter 10) and washing processes (see Section 10.3 in Chapter 10). Suitable methods to measure interfacial tensions as low as 10 3 mN m 1 are the sessile or pendent drop technique [74]. Ultra-low interfacial tensions (as low as 10 r> mN m-1) can be determined with the surface light scattering [75] and the spinning drop technique [76]. 

Mathematically, self-organized spiral patterns are a striking phenomenon of reaction-diffusion systems, in its own right, motivated by a large variety of application areas. 

Probably the most striking phenomenon which is caused by adsorption dynamics is the Marangoni instability. A short introduction into this topic and few demonstrations of observed features are given in Appendix 3C. 

Many chemical systems are known to exhibit bistability when carried out in an open reactor, where the reaction may exist in either of two different steady states for the same experimental operating conditions (such as reactor residence time). This is a striking phenomenon, as the two steady states typically differ significantly in the extent of reaction and, hence, composition. The features of bistability are nicely illustrated by considering a simple reaction comprised of two autocatalytic steps - ... 

Turbulent drag reduction in homogeneous flows by polymer or surfactant additives is a striking phenomenon with both theoretical and practical implications. On the theoretical side, it remains a challenge to fully understand the drag reduction mechanism and the interaction details between DRAs and the turbulent flow field. New methods, especially computational ones, have been developed to solve this problem, such as direct numerical simulations and stochastic simulations. On the application... 

As molecular motion in a gas or liquid is free and random, the physieal properties of these fluids are the same no matter in what direetion they are measured. In other words, they are isotropic. True amorphous solids, beeause of the random arrangement of their constituent molecules, are also isotropic. Most crystals, however, are anisotropic, their mechanical, electrical, magnetic and optical properties can vary according to the direction in which they are measured. Crystals belonging to the cubic system are the exception to this rule their highly symmetrical internal arrangement renders them optically isotropic. Anisotropy is most readily detected by refractive index measurements, and the striking phenomenon of double refraction exhibited by a clear crystal of Iceland spar (calcite) is probably the best-known example. 

As for a charged droplet, probably the most striking phenomenon is the spike behavior at the pole of a stretching droplet that ejects atomized droplets whose mass constitutes less than 1% of the parent droplet, but carrying more than one third of the total charges. This jetting of the spike occurs when the droplet charge exceeds... 

---