First Observable Event

It is commonly stated that the first readily observable event at the interface between a material and a biological Quid is protein or macromolecule adsorption. Clearly other interactions precede protein adsorption water adsorption and possibly absorption (hydration effects), ion bonding and electrical double layer formation, and the adsorption and absorption of low molecular weight solutes — such as amino acids. The protein adsorption event must result in major perturbation of the interfacial boundary layer which initially consists of water, ions, and other solutes. 

Body fluids have a rich and complex composition, permitting a wide range of interactions and competitive processes. 

The great majority of the available work has focused on blood/plasma/serum applications. In recent years the interaction of tear components with contact lenses have become very important. 

Much of the early work is reviewed by Brash and Lyman 1) and by Vroman 2). Protein adsorption is a very old field — the earliest studies probably being mono-molecular film observations using Langmuir-Blodgett troughs 3). A comprehensive monograph which reviews protein adsorption is now available 4). 

Early observations showed that blood clotted faster in clean glass tubes than in siliconized glass. When Mr. Hageman s blood failed to clot in vitro, it was speculated that a Hageman Factor was responsible for the in vitro activation of blood coagulation (see Ref. 2) for a delightful account). 

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Several investigators have found that foreign surfaces, when exposed to blood, adsorb plasma proteins (21, 22). Platelet adhesion to this proteinated surface is the first observable event in thrombosis on the foreign surface. If we consider the proteinated surface as an acceptor in a platelet adhesion mechanism (23), the significance of the nature and composition of adsorbed protein is its role in platelet adhesion (24). 

Events that take place on a grand scale often can be traced to the molecular level. An excellent example is the depletion of the ozone layer in the Earth s stratosphere. The so-called ozone hole was first observed above the Antarctic in the 1980s and is now being observed above both the Arctic and Antarctic poles. The destruction of ozone in the stratosphere is caused primarily by reactions between chlorine atoms and ozone molecules, as depicted in our molecular inset view. 

Screening techniques are relatively cost-effective and require only a small chemical sample however, they do not measure gas evolution or maximum pressure rise. A material is generally considered to be thermally stable if the temperature at which energy from reaction is first observed is at least 100 degrees Celsius (°C) above the maximum operating temperature of a process event under upset conditions (CCPS 1995b p. 93). 

Chemically induced dynamic nuclear polarization is a spectroscopic technique that takes advantage of the coupling between electron and nuclear spins to detect products of radical recombinations by nuclear resonance. It is suited to investigation of the dynamics of radical processes, particularly the events just preceding radical recombinations. First observed in 1967 by Bargon and Fischer32 and independently by Ward and Lawler,33 the phenomenon consists of... 

Public interest in radioactive aerosols began in the mid-1950s, when world-wide fallout of fission products from bomb tests was first observed. The H-bomb test at Bikini Atoll in 1954 had tragic consequences for the Japanese fisherman, and the inhabitants of the Ronge-lap Atoll, who were in the path of the fallout. In 1957, radio-iodine and other fission products, released in the accident to the Windscale reactor, were tracked over much of Europe, and these events were repeated on a much larger scale after the Chernobyl accident. 

The study design included three comparisons ACTIVE W ACTIVE A, and ACTIVE I in 14,000 patients, (Maximum follow-up was for 48 months), The primary endpoint was the time to first vascular event (stroke, Ml, vascular death, systemic emboli). ACTIVE W arm was halted when 6600 patients were enrolled because there a clear benefit from warfarin treatment compared to clopidogrel + aspirin 3.63% of vascular events versus 5,64% (P = 0,0002). Subgroup analysis showed that these disappointing results were observed in patients on warfarin prior to study (HR = 1.5, P = 0.0006), but there was no difference between the two strategies—when the patients were not on warfarin prior to study (HR = 1.32, P = 0,17), Nevertheless, further results are awaited from the ACTIVE-A arm (ASA or ASA + clopidogrel) in patients who cannot or would not take OAC. 

While many of the observed events of the MBH reaction could be included in this scheme, the mechanism failed in some critical cases [47]. First, the mechanism did not provide any clue as to why stereocontrol is so difficult in MBH reactions. Privileged nucleophilic chiral catalysts [48], which in the past have usually allowed good results in related asymmetric transformations, afforded only modest asymmetric induction. This fact was surprising, and pointed to lack of understanding of the basic factors governing the selectivity of the reaction. Other obser-... 

Suppose two events are observed from one of the two earths and that the distance between them is found to be d and the time between them to be t. Also suppose that the same two events are observed from the other earth and that the distance between them is found to be d and the time between them to be t. We suppose the two earths to be moving relatively to each other with any uniform velocity in a straight line so that t will not be equal to t nor d to d. If we suppose that a body was present at both the events, so that it moved the distance between them in the time between them, then its velocity would be d/t to the first observer and d /t to the second. 

The first molecular event in odor perception is an interaction of an odorant with a receptor. Evidence exists that these receptors are proteins, i.e. chiral, so this first interaction should be enantioselective, meaning that these receptors react differently with the two enantiomeric forms of a chiral odorant leading to differences in odor strength and quality. In many cases, this fact has been observed.This paper describes the enantioselective syntheses of some known odorants of multiple chemical classes and discusses the differences of the organoleptic properties of their enantiomeric forms. 

Genuine new directions in research are unanticipated. They are unlikely to be part of a research proposal. It is the unanticipated event (such as the first observation of 02PtFe) which is so important, and has to be followed up. A new viewpoint then develops. In such a way Noble-Gas Chemistry was born. 

The potentially strong involvement of halogens in tropospheric chemistry was first observed in the Arctic, where strong ozone depletion events were found to coincide with high levels of bromine (Barrie et al., 1988). 

An appealing approach to the study of nucleation is to observe it directly in a computer simulation using the method of molecular dynamics. It is evident that one cannot closely mimic experimental conditions, since computer time scales extend only over tens to hundreds of picoseconds. Thus deep quenches carried out at high quench rates are necessary to form supercooled liquids that have some reasonable chance of nucleating. Under such conditions glass formation is also observed, and in fact the first observation of nucleation was a chance event, although since that time more systematic studies have been carried out. 

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