Delicate Balance

We ve all heard about the ravages of acid rain. Resulting from toxic emissions in the environment, acid rain damages the leaves and needles on trees, reduces a tree s ability to withstand cold, drought, disease, and pests, and even inhibits or prevents plant reproduction. In an effort to stay alive and combat the acidity, tree roots pull important nutrients such as calcium and magnesium from the soil. These alkaline nutrients balance the effects of acid rain, but as they become depleted from the soil, the trees ability to survive is further strained. 

The average pH of rain in the eastern American states and in southern Ontario and Quebec is about 40 times more acidic than experts suggest it should be. That water acidifies soil, lakes, and the air, over time causing significant and potentially irreversible damage to the whole ecosystem.1 In addition, higher acidity in seawater reduces the oxygen available to marine creatures and prevents the proper formation of skeletons. This means a reduction in the food supply for both marine life and humans. 

A highly acidic diet is like acid rain in our bloodstreams. We are polluting our bodies on an individual level the same way we are polluting our planet. Because of our poor choices, we are essentially microcosms of the same problems our planet faces. The difference is that most of us are aware that we are polluting the planet, yet few of us realize that we are subjecting our bodies to similar internal pollution and acid waste. 

Tike trees and sea creatures, to support our internal habitat we need water that is neither too acidic nor too alkaline. In the United States, over 80 percent 

In addition to clean water, we (like trees and sea creatures) need an oxygenated environment in our bodies. If we lack oxygen at the cellular level, we create an environment that is ripe for anaerobic (meaning without oxygen ) fermentation, the type of environment in which yeasts, fungi, molds, and cancers thrive. (I will discuss this further in chapter 3.) 

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Protein-DNA complexes present demanding challenges to computational biophysics The delicate balance of forces within and between the protein, DNA, and solvent has to be faithfully reproduced by the force field, and the systems are generally very large owing to the use of explicit solvation, which so far seems to be necessary for detailed simulations. Simulations of such systems, however, are feasible on a nanosecond time scale and yield structural, dynamic, and thermodynamic results that agree well with available experimen-... 

It can be inferred from the first section of this chapter that many different forces work together in a delicate balance to determine the overall three-dimensional structure of a protein. These forces operate both within the protein structure itself and between the protein and the water solvent. How, then, does nature dictate the manner of protein folding to generate the three-dimensional... 

Metabolic regulation is achieved through an exquisitely balanced interplay among enzymes and small molecules, a process symbolized by the delicate balance of forces in this mobile. tSea Scape by Alexander Calder/Whitney Museum of American Art, NY)... 

The operation of a large synthetic ammonia plant based on natural gas involves a delicately balanced sequence of reactions. The gas is first desulfurized to remove compounds which will poison the metal catalysts, then compressed to 30 atm and reacted with steam over a nickel catalyst at 750°C in the primary steam reformer to produce H2 and oxides of carbon ... 

The delicate balance between ionic and covalent forms is influenced not only by the state of aggregation (solid, liquid, gas) or the nature of the solvent, but also by the effect of substituents. Thus PhPCl4 is molecular with Ph equatorial whereas the corresponding methyl derivative is ionic, [MePClsl+Cl". Despite this the [PhPCl3]+... 

Organometallic chemistry of pyrrole is characterized by a delicate balance of the ti N)- and -coordination modes. Azacymantrene is an illustration of the considerable nucleophilicity of the heteroatom. However, azaferrocene can be alkylated at C2 and C3 sites. Ruthenium and osmium, rhodium, and iridium chemistry revealed the bridging function of pyrroles, including zwitterionic and pyrrolyne complex formation. The ti (CC) coordination of osmium(2- -) allows versatile derivatizations of the heteroring. 

It will be seen that the operation of this two-pipe cooling and heat pump circuit is delicately balanced, and requires electronic control of the compressor and outdoor fan speeds in order to pump the right amount of gas, and still maintain working pressures. 

The most delicate balance can detect a change of about 10-8 gram. How many atoms of gold would be in a sample of that weight ... 

The salt attack is also an important factor determining the SAH efficiency in the soil medium. In terms of Eq. (4.3), it is manifested by a sharp decrease of the coefficients y and B. The hydrogel structure prediction for specific application conditions requires to take into account universal (ionic strength) and specific (collapse) suppression phenomena and, therefore, a rather delicate balancing in search for a compromise between swelling gains due to the network density (n ) and the ionicity ((3). 

Because the enthalpy of solution is positive, there is a net inflow of energy as heat when the solid dissolves (recall Fig. 8.23b). Sodium chloride therefore dissolves endothermically, but only to the extent of 3 kj-mol-1. As this example shows, the overall change in enthalpy depends on a very delicate balance between the lattice enthalpy and the enthalpy of hydration. 

The solubilities of the ionic halides are determined by a variety of factors, especially the lattice enthalpy and enthalpy of hydration. There is a delicate balance between the two factors, with the lattice enthalpy usually being the determining one. Lattice enthalpies decrease from chloride to iodide, so water molecules can more readily separate the ions in the latter. Less ionic halides, such as the silver halides, generally have a much lower solubility, and the trend in solubility is the reverse of the more ionic halides. For the less ionic halides, the covalent character of the bond allows the ion pairs to persist in water. The ions are not easily hydrated, making them less soluble. The polarizability of the halide ions and the covalency of their bonding increases down the group. 

A careful examination of all the data indicates a delicate balance between a concerted elimination, path E in Scheme XI, and a unimolecular ionization... 

One of the major concerns for law-enforcement agencies in using less-lethal ammunition projectiles is the delicate balance between their effectiveness and their lethality. Impact biomechanics studies of a human body, including the use of less-lethal projectiles, are critically important when considering the protection of military personnel and civilians from accidental injury. 

Meanwhile, Crutzen had done experiments showing that ozone in the upper atmosphere can be destroyed easily by reactions with nitrogen oxides. This work demonstrated that the ozone layer is in a delicate balance that could be disturbed significantly by changes in atmospheric composition. In 1974, Molina and Rowland combined Crutzen s experimental work with their own theoretical analysis and published a prediction (hypothesis) that CFCs pose a serious threat to the ozone layer. 

The interactions of molecules and light in the ozone layer result in a delicate balance that holds ozone concentration at a relatively constant value. Three reactions maintain this balance ... 

Catalysts are immensely beneficial in industry, but accidental catalysis in the atmosphere can be disastrous. Recall from Box that the chemishy of ozone in the stratosphere involves a delicate balance of reactions that maintain a stable concentration of ozone. Chlorofiuorocarbons (CFCs) shift that balance by acting as catalysts for the destruction of O3 molecules. 

Living cells are delicately balanced chemical machines. The ionization track generated by a nuclear particle upsets this balance, almost always destroying the cell in the process. Although the body has a remarkable ability to repair and replace damaged cells, exposure to radiation can overload these control mechanisms, causing weakness, illness, and even death. 

The data in Figs. 2 and 3 suggest a reaction which requires a delicate balance between adsorbate coverages, consistent with a Langmuir-Hlnshelwood mechanism. More extensive data of this type (24-27) indicate that molecularly adsorbed ethylene and O2 are the critical species, consistent with the mechanism proposed below. 

Treatment involves a delicate balance between diuretics, vasodilators, and inotropic agents... 

A delicate balance between host and donor effector cells is necessary, and residual host-versus-graft effects may lead to graft failure, which is also known as graft rejection. Graft failure is defined as the lack of functional hematopoiesis after HCT and can occur early (i.e., lack of initial hematopoietic... 

A delicate balance of normal pressure is maintained in the brain and spinal cord by brain, blood, and cerebrospinal fluid (CSF) volume. Since the brain is contained within a confined space (skull), any foreign mass contained within that space causes adverse sequelae. This results in either destruction or displacement of normal brain tissue with associated edema. Most brain metastases occur through hematogenous spread of the primary tumor, and around 80% of patients will have multiple sites of metastases within the brain. 

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