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Nonvalence states of neutral molecules (Rydberg states) play important roles in nonadiabatic dynamics of excited states. In anions, such nonadiabatic transitions between nonvalence and valence states have been much less explored even though they are believed to play important roles in electron capture and excited state dynamics of anions. The aim of this Feature Article is to provide an overview of recent experimental observations, based on time-resolved photoelectron imaging, of valence to nonvalence and nonvalence to valence transitions in anions and to demonstrate that such dynamics may be commonplace in the excited state dynamics of molecular anions and cluster anions.

The anion−π bond has emerged as an important nonvalence interaction in supramolecular and biological structure. Although recognized as a strong noncovalent interaction, driven by electrostatic charge-quadrupole moment and correlation interactions, benchmark experimental and computational studies on the intrinsic anion−π bond strength are scarce. Here, we present a gas-phase photoelectron spectroscopic study on the archetypical iodide-hexafluorobenzene anion−π bonded complex. In combination with high-level electronic structure calculations, the anion−π bond strength is found to be 0.53 eV (51 kJ mol–1). The interaction arises for a large part from correlation forces (∼40%), with electrostatic quadrupole-anion and polarization making up most of the remainder.

Frequency-resolved (2D) photoelectron (PE) spectra of the anionic clusters (C6F6)n–, for n= 1–5, and time-resolved PE spectra of I–C6F6are presented using a newly built instrument and supported by electronic structure calculations. From the 2D PE spectra, the vertical detachment energy (VDE) of C6F6–was measured to be 1.60 ± 0.01 eV, and the adiabatic detachment energy (ADE) was ≤0.70 eV. The PE spectra also contain fingerprints of resonance dynamics over certain photon energy ranges, in agreement with the calculations. An action spectrum over the lowest resonance is also presented. The 2D spectra of (C6F6)n–show that the cluster can be described as C6F6–(C6F6)n−1. The VDE increases linearly (200 ± 20 meV n–1) due to the stabilizing influence on the anion of the solvating C6F6molecules. For I–C6F6, action spectra of the absorption just below both detachment channels are presented. Time-resolved PE spectra of I–C6F6excited at 3.10 eV and probed at 1.55 eV reveal a short-lived nonvalence state of C6F6–that coherently evolves into the valence ground state of the anion and induces vibrational motion along a specific buckling coordinate. Electronic structure calculations along the displacement of this mode show that at the extreme buckling angle the probe can access an excited state of the anion that is bound at that geometry but adiabatically unbound. Hence, slow electrons are emitted and show dynamics that predominantly probe the outer-turning point of the motion. A PE spectrum taken at t= 0 contains a vibrational structure assigned to a specific Raman- or IR-active mode of C6F6.

The primary electron-attachment process in electron-driven chemistry represents one of the most fundamental chemical transformations with wide-ranging importance in science and technology. However, the mechanistic detail of the seemingly simple reaction of an electron and a neutral molecule to form an anion remains poorly understood, particularly at very low electron energies. Here, time-resolved photoelectron imaging was used to probe the electron-attachment process to a non-polar molecule using time-resolved methods. An initially populated diffuse non-valence state of the anion that is bound by correlation forces evolves coherently in ∼30 fs into a valence state of the anion. The extreme efficiency with which the correlation-bound state serves as a doorway state for low-energy electron attachment explains a number of electron-driven processes, such as anion formation in the interstellar medium and electron attachment to fullerenes.

The article discusses minimum distribution system method to determine percentage of an electric utility's distribution system required to serve customers and zero-intercept regression method to identify customer cost-related percentage for the U.S. Federal Energy Regulatory Commission account.

Many school psychologists focus their interpretation on composite scores from intelligence test batteries designed to measure the broad abilities from the Cattell–Horn–Carroll theory. The purpose of this study was to investigate the general factor loadings and specificity of the broad ability composite scores from one such intelligence test battery, the Woodcock–Johnson III Tests of Cognitive Abilities Normative Update (Woodcock, McGrew, Schrank, & Mather, 2007). Results from samples beginning at age 4 and continuing through age 60 indicate that Comprehension–Knowledge, Long-Term Retrieval, and Fluid Reasoning appear to be primarily measures of the general factor at many ages. In contrast, Visual-Spatial Thinking, Auditory Processing, and Processing Speed appear to be primarily measures of specific abilities at most ages. We offer suggestions for considering both the general factor and specific abilities when interpreting Cattell–Horn–Carroll broad ability composite scores.

Many school psychologists focus their interpretation on composite scores from intelligence test batteries designed to measure the broad abilities from the Cattell–Horn–Carroll theory. The purpose of this study was to investigate the general factor loadings and specificity of the broad ability composite scores from one such intelligence test battery, the Woodcock–Johnson III Tests of Cognitive Abilities Normative Update (Woodcock, McGrew, Schrank, & Mather, 2007). Results from samples beginning at age 4 and continuing through age 60 indicate that Comprehension–Knowledge, Long-Term Retrieval, and Fluid Reasoning appear to be primarily measures of the general factor at many ages. In contrast, Visual-Spatial Thinking, Auditory Processing, and Processing Speed appear to be primarily measures of specific abilities at most ages. We offer suggestions for considering both the general factor and specific abilities when interpreting Cattell–Horn–Carroll broad ability composite scores.

Transcriptional control of the hgl 5 gene of Entamoeba histolytica is mediated through an unusual core promoter composed of TATA, GAAC and Initiator elements. In the hgl 5 promoter the GAAC element (AATGAACT) determines the site and rate of transcription initiation. Here we tested the role of the GAAC element in transcription activation from upstream regulatory elements (UREs) in the hgl 5 promoter. We also examined the function of the GAAC element in the ferredoxin ( fdx ) promoter and characterized the protein binding to the GAAC element. Electrophoretic mobility shift assays (EMSA) demonstrated that the GAAC region is necessary for higher-order nuclear protein complex assembly. The function of the GAAC element in transcription activation mediated by UREs revealed that mutation of the GAAC element did not affect transcription activation mediated by the hgl 5 URE4 but abrogated activation by the hgl 5 URE3. We compared the role of the GAAC elements in the hgl 5 and fdx promoters. Competitive gel shift assays were consistent with the same nuclear protein binding to the GAAC elements in both genes. Mutation of the GAAC element in the fdx gene decreased reporter gene expression, however, in contrast to hgl 5 gene, had no effect on the site of transcription initiation. These results support a role for the GAAC element in assembly of nuclear proteins at the core promoter and in transcription activation mediated by URE3. The differing effect on transcription initiation in the hgl 5 and fdx genes upon mutation of the GAAC element suggests a context-dependence of the GAAC-binding protein in gene expression.

Killing of human cells by the parasite Entamoeba histolyticarequires adherence via an amebic cell surface lectin. Lectin activity in the parasite is regulated by inside-out signaling. The lectin cytoplasmic domain has sequence identity with a region of the β2 integrin cytoplasmic tail implicated in regulation of integrin-mediated adhesion. Intracellular expression of a fusion protein containing the cytoplasmic domain of the lectin has a dominant negative effect on extracellular lectin-mediated cell adherence. Mutation of the integrin-like sequence abrogates the dominant negative effect. Amebae expressing the dominant negative mutant are less virulent in an animal model of amebiasis. These results suggest that inside-out signaling via the lectin cytoplasmic domain may control the extracellular adhesive activity of the amebic lectin and provide in vivo demonstration of the lectin’s role in virulence.

Entamoeba histolytica, an enteric protozoa, is the third leading parasitic cause of death worldwide. Investigation of the transcriptional machinery of this eukaryotic pathogen has revealed an unusual core promoter structure that consists of nonconsensus TATA and initiator regions and a novel third conserved core promoter sequence, the GAAC element. Mutation of this region in the hgl5 promoter decreases reporter gene expression and alters the transcription start site. Using positional analysis of this element, we have now demonstrated that it is able to direct a new transcription start site, 2–7 bases downstream of itself, independent of TATA and Inr regions. The GAAC region was also shown to control the rate of transcription via nuclear run on analysis and an amebic nuclear protein was demonstrated to specifically interact with this sequence. This is the first description in the eukaryotic literature of a third conserved core promoter element, distinct from TATA or initiator regions, that is able to direct a transcription start site. We have formulated two models for the role of the GAAC region: (i) the GAAC-binding protein is a part of the TFIID complex and (ii) the GAAC-binding protein functions to “tether” TATA-binding protein to the TATA box.

Several letters to the editor and response by the authors are presented in response to articles in previous issues including "The Dermatologist and the Magician," by Sonny Saggar, "Money Lies and the Dwindling Antibiotic Pipeline," by Stephen J. Playe and a feature story by James Roberts on methicillin-resistant Staphylococcus aureus.