Experiment and Explanation

DNA contains the hereditary information of an organism that is passed on from one generation to the next. 

Experiment and explanation are the heart of chemical research. A chemist makes observations under circumstances in which variables, such as temperature and amounts of substances, can be controlled. An experiment is an observation of natural phenomena carried out in a controlled manner so that the results can be duplicated and rational conclusions obtained. In the chapter opening it was mentioned that Rosenberg studied the effects of electricity on bacterial growth. Temperature and amounts of nutrients in a given volume of bacterial medium are important variables in such experiments. Unless these variables are controlled, the work cannot be dupH-cated, nor can any reasonable conclusion be drawn. 

Have you ever used a Post-it and wondered where the idea for those little sticky notes came from You have a chemist to thank for its invention. The story of the Post-it Note is one that illustrates how the creativity and insights of a scientist can result in a prodnct that is as common in the office as the stapler or pen. 

Still thinking about his problem the next day. Fry consulted a colleague, Spencer Silver, who was studying adhe- 

Part of Fry s job description at 3M was to spend time working on creative ideas such as his bookmark. As a result, he continued to experiment with the bookmark to improve its properties of sticking, detaching, and not hurting the surface to which it was attached. One day, while working on some paperwork, he wrote a question on one of his experimental strips of paper and sent it to his boss stuck to the top of a file folder. His boss then answered the question on the note and returned it attached to some othCT documents. During a later discussion over coffee. Fry and his boss realized that they had invented a new way for people to communicate the Post-it Note was bom. The Post-it Note is one of the top-selling office products sold in the 

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Practical activities should embody as best as possible the scientifie proeesses that have been preseribed by the American Association for the Advancement of Science observation, elassification, numerieal relations, measurements, time-spaee relations, eommunieation (oral, pictorial, written), deriving of conclusions, prediction ( what would happen if. .hypothesis making, production of operational definitions, identifieation and control of variables, experiment and explanation of experimental data. Different theoretical perspectives should be used with the aim to optimize the positive eognitive and affeetive outcomes. The use, sometimes together, sometimes separately, of different perspeetives can act complimentarily and can lead to positive results (Niaz, 1993 Tsaparhs, 1997). 

The two aspects of science, experiment and explanation, are closely related. A scientist performs experiments and observes some regularity someone explains this regularity and proposes more experiments and so on. From his experiments, Rosenberg explained that certain platinnm componnds inhibit cell division. This explanation led him to do new experiments on the anticancer activity of these compounds. 

Plazek D J (2007) Anomalous viscoelastic properties of polymers Experiments and explanations, J Non-Cryst Solids 353 3783-3787. 

The tetrad effect in the lanthanoid series — experiment and explanation. 

C. Daniel, App/ications of Statistics to lndustria/Experimentation, ]oE Wiley Sons, Inc., New York, 1976. This book is based on the personal experiences and insights of the author, an eminent practitioner of industrial appHcations of experimental design. It provides extensive discussions and concepts, especially in the areas of factorial and fractional factorial designs. "The book should be of use to experimenters who have some knowledge of elementary statistics and to statisticians who want simple explanations, detailed examples, and a documentation of the variety of outcomes that may be encountered." Some of the unusual features are chapters on "Sequences of fractional repHcates" and "Trend-robust plans," and sections entided, "What is the answer (what is the question )," and "Conclusions and apologies."... 

The second law as it left the hands of Carnot required no explanation. On the caloric theory then prevalent, it was a necessary consequence of a hydrodynamical analogy—the mechanical explanation was in fact, as Carnot s words show, the source of the principle. When the caloric theory was thrown down, the analogy and explanation fell with it, and the reconstruction of Carnot s principle by Clausius and Kelvin resulted in a law of experience. 

But similar calculations for the iron-group ions show marked disagreement with experiment, and many attempts were made to explain the discrepancies. The explanation is simple in many condensed systems the perturbing effect of the atoms or molecules surrounding a magnetic atom destroys the contribution of the orbital momentum to the magnetic moment, which is produced entirely by the spin moments of unpaired electrons.40... 

Polymers are not only an important topic of chemistiy because of their matty applications in everybody s daily-life, they are also interesting because of the theories that can be applied to explain and to design polymers and their properties. However, the teaching experiments and interviews gave hints that the historical development of theories to explain polymers and the students explanations are not as coherent as for... 

After these first explanations and discussions, the students were shown some experiments. The explanations were diverse Some students explained the swelhng of SAP as a chemical reaction, not as an uptake of water between the polymer strac-tures. The demonstration of the Tyndall effect was also not helpful to evaluate the two theories in a better way, as both were used again as explanations. 

The fact that mbber shows mbber elasticity was discovered more than 100 years earlier than professor H. Staudinger s proposal. The memory effect acquired by vulcanization, so-called Gough-Joule effect, and its thermodynamic explanation were the great achievements in the nineteenth century. As seen in many textbooks, this thermodynamic approach was the easiest one to gain consistency between ever-performed experiments and theory. In fact, thermodynamics of mbbery material can be treated in parallel with thermodynamics of gas. One could show experimentally that... 

An unexpected outcome from EQA observations appeared when unsatisfactory material was unknowingly used at one time for the manufacture of atomic absorption graphite furnaces. Several laboratories were aware of unsatisfactory IQC for their blood lead methods and strived to find an explanation but it was only when the FQA data revealed a widespread problem that a group of participants compared their recent experience and were able to confirm with the suppliers that inferior graphite had been employed. 

A possible explanation for the difference in tendencies of the deposition rate between experiment and model is that in the model the surface reaction and sticking coefficients of the radicals are taken to be independent of the discharge characteristics. In fact, these surface reaction coefficients may be influenced by the ions impinging on the surface [251]. An impinging ion may create an active site (or dangling bond) at the surface, which enhances the sticking coefficient. Recent experiments by Hamers et al. [163] corroborate this the ion flux increases with the RF frequency. However, Sansonnens et al. [252] show that the increase of deposition rate cannot be explained by the influence of ions only. 

The effect of hydrogen pressure in the reaction network and kinetics of quinoline hydrodenitrogenation has been matter of debate. Some controversial results and explanation were raised by the proposal of light hydrocarbons formation [78], The lack of observation of these hydrocarbons in previous experiments was explained by the low pressure employed and the deviations observed of the mass balances in these experiments were an evidence for the formation of lights HCs. The controversy is not clear yet and might be the subject for further investigations. 

A typical breakthrough curve was observed for the column filled with Zr-loaded activated carbon after about 8000 pore volumes. This correspond to a uptake of 2.8 mg As/g. The concentrations in the outlet of the column with Absorptionsmittel 3 increased after about 4000 pore volumes, but no typical breakthrough curve was observed. The uptake until this point was only 2 mg As/g that is much lower than it was determined in the batch experiments. An explanation for this early increasing of the concentrations may be the high flow rate in comparison of the slow kinetics. The best results gave the column filled with the granular iron hydroxide. No breakthrough was observed up to now (12,000 pore volumes) and an uptake of about 2 mg As/g could be measured. The arsenite concentrations in the outlet of all three columns were very low and indicate an oxidation reaction. 

The nature of the antigenic determinant has been characterized in a male worker with occupational asthma from nickel [415, 416] the antibody recognized Ni2+ bound at the natural Cu2 + /Ni2+ transport site of human albumin. The interpretation was deduced from metal ion blocking experiments and from the good agreement obtained between the pH dependency of the formation of the Ni2 + -albumin complex and the antigen-antibody complex. It was suggested that the antibody interaction depended on a special structural feature of the interaction of Ni2 + with human serum albumin, and perhaps the ability to form an octahedral complex affords one explanation [417]. 

These experiments and similar ones with other monomers, to be described elsewhere, show that the explanation of the allegedly cationic polymerisations of aromatic monomers in terms of ions must be revised drastically, and that the interpretation of the rate-constants reported must be treated with the greatest circumspection. 

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