Despite the importance of Fe redox cycling in clay minerals, the mechanism and location of electron transfer remain unclear. More specifically, there is some controversy whether electron transfer can occur through both basal and edge surfaces. Here we used Mössbauer spectroscopy combined with selective chemical extractions to study electron transfer from Fe(II) sorbed to basal planes and edge OH-groups of clay mineral NAu-1. Fe(II) sorbed predominantly to basal planes at pH values below 6.0 and to edge OH-groups at pH value 7.5. Significant electron transfer occurred from edge OH-group bound Fe(II) at pH 7.5, whereas electron transfer from basal plane-sorbed Fe(II) to structural Fe(III) in clay mineral NAu-1 at pH 4.0 and 6.0 occurred but to a much lower extent than from edge-bound Fe(II). Mössbauer hyperfine parameters for Fe(II)-reacted NAu-1 at pH 7.5 were consistent with structural Fe(II), whereas values found at pH 4.0 and 6.0 were indicative of binding environments similar to basal plane-sorbed Fe(II). Reference experiments with Fe-free synthetic montmorillonite SYn-1 provided supporting evidence for the assignment of the hyperfine parameters to Fe(II) bound to basal planes and edge OH-groups. Our findings demonstrate that electron transfer to structural Fe in clay minerals can occur from Fe(II) sorbed to both basal planes and edge OH-groups. These findings require us to reassess the mechanisms of abiotic and microbial Fe reduction in clay minerals as well as the importance of Fe-bearing clay minerals as a renewable source of redox equivalents in subsurface environments.

When an individual is seen or treated by a healthcare professional, a series of alphanumeric codes are used to describe the medical diagnoses and services provided. This designated classification structure, the ninth iteration of ICD (International Classification of Diseases), implements the use of coding for healthcare management, public health and medical informatics, and insurance purposes. ICD-9 has been the coding standard in the healthcare industry for 30 years. On October 1st, 2015, the tenth revision ICD-10 was formally implemented in the United States. This paper explores the validity of predictions from domain professionals regarding fraud detection and the implementation of the ICD-10 code set. The notion that fraud detection systems using supervised learning algorithms will encounter an initial decline in performance due to ICD-10 is fairly unsupported at the moment. The authors claim that the results from their study will provide evidence that will support this notion of a preliminary negative transitional impact.

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