Subject historical studies

For the fundamental historical study on this problematic subject, of such wide interest to the early modernist painters, see Henderson, Fourth Dimension. 

Many examples are present in the scientific Uterature underlining the effort in producing kinetic data [9—11]. The Edwards historical study that started the investigation on the mechanism of the hydrolysis of aspirin required hundreds of kinetic experiments [12,13]. Several examples are reported by Carstensen [1] in his review on the subject where, beside the large space dedicated to the determination of the pH-rate profile, the effect of temperature, ionic strength, buffer concentration, and dielectic constant on the stability of drugs was treated. 

The history of any subject is the means by which the subject is studied in the hopes that much can be learned from the events of the past. In the current context, the occurrence and use of petroleum, petroleum derivatives (naphtha), heavy oil, and bitumen is not new. The use of petroleum and its derivatives was practiced in pre-Christian times and is known largely through historical use in many of the older civilizations (Henry, 1873 Abraham, 1945 Forbes, 1958a, 1958b, 1959, 1964 James and Thorpe, 1994). Thus, the use of petroleum and the development of related technology is not such a modem subject as we are inclined to believe (Speight, 1999). 

Analytical chemistry probably continues to grow at a faster rate than any other branch of the subject, and the number of papers published annually in The Analyst has doubled within the last 25 years. Historical studies of analytical chemistry are also appearing in increasing numbers, and many are concerned with techniques that were developed relatively recently. The title of a recent RSC-sponsored lecture for school students on the current direction of analytical chemistry was entitled Finding Out More and More about Less and Less . The present state of the history of analytical chemistry could be described as Finding Out More and More about More and More . 

Information Seeking searehii fm evidence, facts, or knowledge by idenufying re lev am sources and gathering objective, subjective, historical, and current data from those sources f knew [ needed to look up/study."... 

As we mentioned in the introduction, our work is practically the first historical study examining the introduction and uptake of the periodic system in Italy, excepting a few essays, now rather dated, dedicated to a comparison of the work of Piccini and Mendeleev. Naturally, this essay only scratches the surfaces of the subject, which is one that will require further investigation and confirmation in order to understand the reasons behind the swift and whole-hearted acceptance of the periodic system in Italy. We sincerely hope that our work will provide a stimulus for further research in this field. 

The concept of chemical periodicity is central to the study of inorganic chemistry. No other generalization rivals the periodic table of the elements in its ability to systematize and rationalize known chemical facts or to predict new ones and suggest fruitful areas for further study. Chemical periodicity and the periodic table now find their natural interpretation in the detailed electronic structure of the atom indeed, they played a major role at the turn of the century in elucidating the mysterious phenomena of radioactivity and the quantum effects which led ultimately to Bohr s theory of the hydrogen atom. Because of this central position it is perhaps not surprising that innumerable articles and books have been written on the subject since the seminal papers by Mendeleev in 1869, and some 700 forms of the periodic table (classified into 146 different types or subtypes) have been proposed. A brief historical survey of these developments is summarized in the Panel opposite. 

Carbonyl reactions are extremely important in chemistry and biochemistry, yet they are often given short shrift in textbooks on physical organic chemistry, partly because the subject was historically developed by the study of nucleophilic substitution at saturated carbon, and partly because carbonyl reactions are often more difhcult to study. They are generally reversible under usual conditions and involve complicated multistep mechanisms and general acid/base catalysis. In thinking about carbonyl reactions, 1 find it helpful to consider the carbonyl group as a (very) stabilized carbenium ion, with an O substituent. Then one can immediately draw on everything one has learned about carbenium ion reactivity and see that the reactivity order for carbonyl compounds ... 

We begin our review with a brief description of the historic background and basic equations of DFT. For the interested reader there are many excellent textbooks on the subject [1-3] and review books with compilations of results from studies in, e.g., chemistry, biochemistry, or materials science [4-7]. 

The phenomenon of fluorescence has been synonymous with ultraviolet (UV) and visible spectroscopy rather than near-infrared (near-IR) spectroscopy from the beginning of the subject. This fact is evidenced in definitive texts which also provide useful background information for this volume (see, e.g., Refs. 1-6). Consequently, our understanding of the many molecular phenomena which can be studied with fluorescence techniques, e.g., excimer formation, energy transfer, diffusion, and rotation, is based on measurements made in the UV/visible. Historically, this emphasis was undoubtedly due to the spectral response of the eye and the availability of suitable sources and detectors for the UV/visible in contrast to the lack of equivalent instrumentation for the IR. Nevertheless, there are a few notable exceptions to the prevalence of UV/visible techniques in fluorescence such as the near-IR study of chlorophyll(7) and singlet oxygen,<8) which have been ongoing for some years. 

Spanish Hemp Workers. Data collected on hemp workers have been offered in support of chronic respiratory effects associated with cotton dust exposure. Historically, hemp workers constituted the first group to call medical attention to their respiratory effects (27). More recent studies done on hemp workers, however, suggest similar limitations of methodology as mentioned above. The recruitment of subjects leaves much perplexity about the representative character of the group, when the source population is not accounted or even remotely described (28, 29, 30). The exposure length is not assessed (some of the workers have less than two years tenure) and/or the status of "retirement" is used uncritically as an index of exposure (29,... 

Similarly, external or historical controls (groups of subjects external to the study either in a different setting or previously treated) cannot provide definitive evidence. Byar (1980) provides an extensive discussion on these issues. 

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