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Duncan Thorburn Burns is an analytical chemistry researcher named with Klaus Danzer and Alan Townshend as preparing the 2002 IUPAC recommendations on recovery terminology. The paper's full byline identifies Burns at Queen's University Belfast; its publisher record abbreviates him as D. T. Burns.^[ref]

The recommendations distinguish extraction recovery, the yield of a separation or preconcentration step, from apparent recovery, the ratio of an analytically obtained value to a reference value after measurement calibration. These answer different scientific questions: how much analyte reaches the measurement stage, and how the final reported result compares with its reference.^[ref]

An original controlled-response example shows why even an apparent recovery of one can conceal a loss. Stipulate a preparation starting with $10\mu \mathrm{g}$ of analyte, of which $8\mu \mathrm{g}$ reaches a final $1\mathrm{mL}$ solution. The extraction recovery is $8/10=0.80$. Suppose a clean-solvent standard produces one arbitrary signal unit per $\mu g/mL$, while the final sample matrix multiplies the response by $1.25$. The extract then produces ten signal units. A clean-solvent measurement calibration converts that signal to $10\mu g/mL$, equal to the reference concentration for complete recovery:The stipulated signal enhancement exactly compensates for the extraction loss in this example. Agreement of the final result with the reference does not identify either mechanism separately.

A comparison measurement could introduce equal nominal quantities before extraction, after extraction into a matched blank extract, and into clean solvent, with matched final volumes and instrument settings. Comparing their responses separates preparation losses from a response change caused by the sample matrix, under the stated linear-response assumptions. The analytical matrix effect article explains the response distinction. Repeating the example with a matrix-matched calibration slope of $1.25$ gives $c_{\mathrm{found}}=8\mu g/mL$: the apparent recovery then becomes $0.80$. The number depends on the analytical procedure and its calibration, rather than on extraction yield alone.

Burns and his collaborators' terminology makes those experimental distinctions explicit. A reported recovery value therefore needs its definition, reference and calibration procedure; the percentage by itself leaves the measurement ambiguous.

John Cowdery Kendrew helped establish how X-ray crystallography can reveal the three-dimensional arrangement of a protein. Nobel's primary nomination archive names John Cowdery Kendrew, also identifying J. C. Kendrew in its award-sharing comment.^[ref]

His team's1960 myoglobin paper presented a Fourier analysis at2-angstrom resolution. Its opening recalls how earlier phase determination compared native crystals with heavy-atom derivatives containing localized mercury or gold sites. Such comparisons supply information missing from a simple measurement of diffraction intensity.^[ref]

An original one-dimensional example explains that phase problem. Write a periodic electron density using Fourier series coefficients $F_k$. The two positive densitieshave $F_0=3$, $F_{\pm 1}=1/2$ and $F_{\pm 2}=\pm 1/4$, with the final sign distinguishing them. Their squared coefficient magnitudes are identical:9 for mode zero,1/4 for modes $\pm 1$ and1/16 for modes $\pm 2$. The relative phase of the second harmonic has changed while the first harmonic is fixed. Thus equal intensities need not identify one density.

The myoglobin experiment was more demanding than this toy calculation, but the distinction motivates its chemical strategy: modifying crystals at known heavy-atom sites changes their scattering in a way that constrains phase information. Reconstructing an electron density map therefore requires both measured diffraction and a justified phase-determination method, rather than treating the recorded spots as a direct photograph of the molecule.