Chemical dimension

This chapter primarily serves as a review of process fundamentals such as units, dimensions, chemical and physical properties, conservation laws, and engineering principles. 

First, it is useful to understand what we mean by 1-D and 2-D experiments. If you consider a normal proton spectrum, it is plotted in two dimensions (chemical shift on the x axis and intensity on the y), so why is it called 1-D In fact, when NMR started, it wasn t because there was no need to distinguish it from what we now call 2-D. The dimensions that we are talking about are the number of frequency dimensions that the data set possesses. To try to understand we need to explain the basics of the pulse programme. If we take a simple example (e.g., 1-D proton) we can represent the pulse sequence in Figure 8.1. 

E. L. Eliel, Chemistry in three dimensions , Chemical Structure, Springer, Berlin, 1993, pp. 1-8. 

Lichtner (2001) developed the computer code FLOTRAN, with coupled thermal-hydrologic-chemical (THC) processes in variably saturated, nonisothermal, porous media in 1, 2, or 3 spatial dimensions. Chemical reactions included in FLOTRAN consist of homogeneous gaseous reactions, mineral precipitation/dissolution, ion exchange, and adsorption. Kinetic rate laws and redox... 

Murray, R. W. Chemically modified electrodes. Acc. Chem. Res. 1980,13, 135-141. Abruha, H. D. Coordination chemistry in two dimensions chemically modified electrodes. Coord. Chem. Rev. 1988, 86, 135-189. 

NOESY was performed at 32 °C on a VXR-500 spectrometer operating at a proton frequency of 500 MHz. The protein was dissolved in 20 mM sodium phosphate, pH 7.5 (direct pH meter reading), 100 mM NaCl, 5 mM DTT in D2O. The protein concentration was 2 mM. The data was acquired in the hypercomplex mode with a mixing time of 150 ms (Jeener et al., 1979 Macura Ernst,1980). The spectral width was 7200 Hz in both dimensions. 2048 complex points in the t2 dimension and 256 complex points in the tl dimension were acquired. 96 transients were collected for each FID. Data processing was performed on a Sun Sparc 10 station using VNMR software from Varian. The time domain data were zero-filled once and multiplied by shifted sinebell or Gaussian functions before Fourier transformation in both dimensions. Chemical shifts were referenced to internal sodium 3-(trimethylsilyl)-propionate-2,2,3,3-d4. 

SRS (separation in 1st dimension — chemical reaction — separation in 2nd dimension)... 

Abruna HD (1988) Coordination chemistry in two dimensions chemically modified electrode. Coord Chem Rev 86 135-189... 

The first three descriptors have been plotted for 27 amines that have similar values in the remaining two dimensions. Carboxylic acids form a tight cluster near, but separate from, the esters. Alcohols are farther away from the acids, and amines are even farther. Aliphatics are widely separated from aromatics. The formation of these clusters is typical and is what justifies calling these dimensions chemical functionality descriptors. ... 

Polymeric gel can be represented as a two-component system consisting of a stable 3D network of cross-linked polymer chains and molecules of solvent filling the pores in a network (Ulanski et al. 1998). Nanogels are particles of a polymeric gel having nanometer dimensions. Chemical methods... 

With rapid developments in nanoscience and nanotechnology, various nanostructures, including nanotubes (NTs), nanowires (NWs), and nanopaiticles (NPs), have been fabricated using light-emitting polymers [4-6], The intrinsic characteristics of jr-conjugated polymer nanostructures can be controlled through the physical dimensions, chemical processes, and post-synthetic treatments. 

Zeolite catalysts are composed of silicon and aluminum oxides in a crystal structure that is permeated by Intracrystalline pores and cavities of precise and uniform dimensions. Chemical reactions occur primarily within these pores. If the Intracrystalline structure is chosen to have certain precise dimensions, the ease of accommodation of reactant and product molecules will depend critically on the shape of the molecules. It is thus possible to generate molecular shape selective catalysts (12-16). 

Due to their small dimensions, chemically modified field effect transistors are particularly useful for application in flow sensor systems. A double sensor flowthrough cell has been developed for detection of heavy metal ions in aqueous solutions (Figure 3). The cell contains two CHEMFETs of which one is selective for the supporting electrolyte ion (in this case a 0.1 M potassium ion solution) and the other is selective for the heavy metal ion to be detected (Cd , Pb " ). 

Fig. 1.Two-dimensional lattice gas model on a square lattice with open boundaries A and B in one dimension and periodic boundary conditions in the other dimension. Chemical potentials, /i, are applied at the two ends. Black dots denote particles on the lattice. 

Typical natural fillers are extracted from lodes (in quarries or mines), sorted and washed if necessary, nearly always grinded to the appropriate particle size (at least below 10 pm) and sieved with respect to the desired distribution of dimensions. Chemically, mineral white fillers are silicates, carbonates or oxides, with specific surface area ranging from 1 to 50 m /g, therefore considered as inert (i.e., not reinforcing) to semiactive (slightly reinforcing) materials. We briefly describe hereafter the most common white minerals used as fillers for polymer materials. 

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