Organic Chemistry Carruthers , Free 33 ^NEW^
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While an instructor at Illinois, Carothers became interested in the electronic theory of valence to explain how atoms in organic molecules bond together. It was a theory propounded by the physical chemist G. N. Lewis of the University of California at Berkeley. But most organic chemists of the time ignored that theory, if they did not dismiss it outright. Carothers published a paper on the electronic nature of the carbon-carbon double bond in the Journal of the American Chemical Society in 1924. It marked his growing interest in theoretical as well as experimental organic chemistry.
In 1926, Carothers accepted a teaching post in organic chemistry at Harvard University, but he was uncomfortable as a classroom lecturer. When DuPont offered Carothers the opportunity to do fundamental research, at first he was reluctant to accept. He agreed to do so once convinced that he would be free to work on whatever interested him and that he would command an ample budget for supplies and equipment. Stine also provided Carothers with a staff of newly minted Ph.D.s from Colorado, Johns Hopkins, Illinois, MIT, and Michigan. Besides, his $6,000 a year salary would nearly double what Harvard was paying him.
Conceptual diagram showing the biogeochemistry of carbon associated with air-water CO2 exchanges. Blue lines indicate the processes that enhance the uptake of atmospheric CO2, and red lines indicate those that enhance the emission of CO2 into the atmosphere. The CO2 concentration in surface water is primarily responsible for determining the direction of the flux. The concentration of surface water CO2 is determined by carbonate equilibrium in dissolved inorganic carbon (DIC) and affected by net ecosystem production (the balance of photosynthesis, respiration, and remineralization), which directly regulate DIC (1 and 2), allochthonous particulate and dissolved organic carbon (Corg), particulate inorganic carbon (Cinorg), and DIC inputs from terrestrial systems and coastal oceans (3 and 4), net ecosystem Cinorg production (the balance of calcification and dissolution), directly regulating both DIC and total alkalinity (TA) (5, 6), and temperature (solubility of CO2). Calcification produces CO2 with a ratio (released CO2/precipitated Cinorg) of approximately 0.6 in normal seawater54
The basic biogeochemical controls on Corg accumulation within soils are understood (e.g., biochemical nature of the Corg inputs which vary among primary producers115,116,117 and the chemistry of their decomposition products)110, but it remains unclear what controls the stability of stored Corg in BC soils and whether these factors vary across ecosystems or under different environmental conditions (incl. disturbance). With the exception of one recent paper43, we know little about the Corg -mineral associations in BC ecosystems, how these affect the recalcitrance of soil Corg or whether specific forms are protected more by this mechanism than others, though this is clearly the case in other ecosystems118,119,120. Undoubtedly the anaerobic character of BC soils places a significant control on in situ rates of Corg decomposition and remineralisation. However, the time organic materials are exposed to oxygen before entering the anaerobic zone of BC soils will impact the quantity and nature of Corg as will the redox potential reached within the soil. The amount of time organic matter is exposed to oxygen explains the observation that Corg concentrations in tidal marshes globally are higher on coastlines where relative sea level rise has been rapid compared to those where sea level has been relatively stable18. Moreover, exposure of BC to oxygen has been recently shown trigger microbial attack, even ancient (5000-year-old) and chemically recalcitrant BC43. Enhancing our understanding of oxygen exposure times and critical redox potentials will help explain variations in Corg accumulation rates and preservation within different BC ecosystems. 2b1af7f3a8