From Neutral Aniline to Aniline Trication: A Computational and Experimental Study

We report density functional theory computations and photoionization mass spectrometry measurements of aniline and its positively charged ions. The geometrical structures and properties of the neutral and singly, doubly, and triply positively charged aniline are computed using density functional theory with the generalized gradient approximation. At each charge, there are multiple isomers closely spaced in total energy. Whereas the lowest energy states of both neutral and cation have the same topology C₆H₅-NH₂, the dication and trication have the C₅NH₅-CH₂ topology with the nitrogen atom in the meta- and para-positions, respectively. We compute the dissociation pathways of all four charge states to NH or NH⁺ and NH₂ or NH₂⁺, depending on the initial charge of the aniline precursor. Dissociation leading to the formation of NH (from the neutral and cation) and NH⁺ (from the dication and trication) proceeds through multiple transition states. On the contrary, the dissociation of NH₂ (from the neutral and cation) and NH₂⁺ (from the dication and trication) is found to proceed without an activation energy barrier. The trication was found to be stable toward abstraction on NH⁺ and NH₂⁺ by 0.96 and 0.18 eV, respectively, whereas the proton affinity of the trication is substantially higher, 1.98 eV. The mass spectra of aniline were recorded with 1300 nm, 20 fs pulses over the peak intensity range of 1 × 10¹³ to 3 × 10¹⁴ W cm^-2. The analysis of the mass spectra suggests high stability of both dication and trication to fragmentation. The formation of the fragment NH⁺ and NH₂⁺ ions is found to proceed via Coulomb explosion.

Response selection and execution skills of professionals and novices during singles tennis competition

This study extended research on sport expertise concerning the development of cognitive and motor skills in singles tennis (McPherson, 1999). 12 adult male professional and novice tennis players were videotaped during singles competition. Opponents for matches were randomly selected within each group of participants. Two tennis experts utilized an observational scale to judge players' performance generated during competition for serves and shots following the serve, e.g.. return of serves, lobs. Each player was scored on three performance components: quality of movement to or control of the ball for serves or shots attempted (control skills), appropriateness of serve or shot selections in the context of game situations (response selection skills), and quality of serves or shots produced (response execution skills). Relative frequency scores for the highest category of each performance component were derived according to the number of opportunities to respond. Serve performance indicated both groups were able to control their serves: however, professionals made more tactical selections and forceful executions. Shot performance indicated professionals made more successful movement to and control of shots, tactical shot selections, and forcing shot executions than novices. Overall, players' tactical response selections were greater than their forceful response executions. Thus, assessing players' decisions during competition may provide vital information concerning tactical skill development. Further, professional players exhibited higher and more consistent tactical behavior than elite collegiate players examined in 1999 by McPherson. Findings were attributed to tactical knowledge and motor skill development resulting from competition and practice experiences.

Phenobarbital pre-treatment prevents kainic acid-induced impairments in acquisition learning

This study examined the protective effect of phenobarbital on kainic acid-induced deficits in acquisition learning. A single kainic acid injection (9 mg/kg i.p.) was administered five days prior to testing using the Morris water maze test. Kainic acid produced deficits in the acquisition of spatial information observed as an increase in latency to a hidden escape platform. Daily phenobarbital treatment (20 mg/kg i.p.) initiated 45 minutes prior to the kainic acid injection blocked the kainic acid-induced deficits in acquisition learning. When daily phenobarbital treatment was initiated 2-3 hours after kainic acid seizure development it did not block the kainic acid induced-deficits in water maze performance. Daily administration of phenobarbital alone at the moderate concentration used in this study did not cause alterations in behavioral performance in the Morris water maze. These studies indicate that phenobarbital pre-treatment results in a behavioral neuroprotection against kainic acid-induced neurotoxicity.

Tactical differences in problem representations and solutions in collegiate varsity and beginner female tennis players

Youth tennis experts' tactical problem representations have been linked to their superior response selections during competition (McPherson & Thomas, 1989). To expand this research to adults, collegiate varsity (experts, n = 6) and beginner (novices, n = 6) female tennis players participated in an interview session to elicit problem representations and solutions to six tennis game situations. Interviews, transcribed verbatim, were coded for accuracy in solutions to each situation. Novices did not generate any solutions (actions), while experts generated similar and tactical solutions. Quantitative analysis of verbal data revealed expertise differences in problem representations and solution processes. Mann-Whitney U tests revealed that experts accessed more tactical and associated response selection and response execution concepts than novices. Findings indicate that experts will generate specialized cognitive processes to develop, monitor, and regulate their condition profiles and action plans during competition.

Expert-novice differences in performance skills and problem representations of youth and adults during tennis competition

Expert and novice tennis players selected from three different age groups (i.e., 10-11 years, 12-13 years, and collegiate adults) were examined for differences in performance skills (i.e., behavioral analyses of video recordings) and problem representations (i.e., verbal report analyses of tape recordings) during matched competition. Factorial analyses of variance on behavioral measures indicated that experts' performances exhibited higher levels of decision and execution than novices, regardless of age. Kruskal-Wallis tests on verbal report measures indicated that experts generated more total, varied, and sophisticated condition and action concepts than novices. Within experts, adults accessed more sophisticated problem representations than youth. Both current event and action plan profiles guided and mediated adult experts' response selections and executions, respectively. Youth experts primarily used action plan profiles to guide their response selections. Novices, regardless of age, accessed weak problem representations.

Knowledge representation and problem solution in expert and novice youth baseball players

The purpose of this study was to examine differences in knowledge representation and problem solutions in expert and novice youth baseball players. Ninety-four players in two age divisions, 7-8 years of age and 9-10 years of age, were assigned to three levels of expertise: high; average; and low skilled. Each subject participated in an interview session to elicit knowledge representation and solutions to five different defensive game situations. Interviews were transcribed and analyzed for content, solution to the problem, errors in problem solution, and qualitative trends. The frequency of advanced solutions to each of the five situations were analyzed in separate chi-square tests for age and expertise. Differences among the levels of expertise were found for the accuracy of solutions to three complex situations. Age was significant for only one situation. Patterns of knowledge content accessed during advanced and less advanced responses indicated both experts and novices were in a beginning stage of developing baseball knowledge structures. Errors in problem solutions indicated children had difficulty monitoring critical conditions and making correct inferences. Players' and teammates' ability to execute baseball skills seemed to influence the content and structure of tactical knowledge accessed during problem solution.

Modification of the coding sequence enhances plant expression of insect control protein genes

Increased expression of the insect control protein genes of Bacillus thuringiensis in plants has been critical to the development of genetically improved plants with agronomically acceptable levels of insect resistance. The expression of the cryIA(b) gene was compared to partially modified (3% nucleotide difference) and to fully modified (21% nucleotide difference) cryIA(b) and cryIA(c) genes in tobacco and tomato. The modified genes increased the frequency of plants that produced the proteins at quantities sufficient to control insects and dramatically increased the levels of these proteins. Among the most highly expressing transformed plants for each gene, the plants with the partially modified cryIA(b) gene had a 10-fold higher level of insect control protein and plants with the fully modified cryIA(b) had a 100-fold higher level of CryIA(b) protein compared with the wild-type gene. Similar results were obtained with the fully modified cryIA(c) gene in plants. Specific sequences of the partially modified cryIA(b) gene were analyzed for their ability to affect cryIA(b) gene expression in tobacco. The DNA sequence of a single region was identified as important to the improvement of plant expression of the cryIA(b) gene. The increased levels of cryIA(b) mRNA were not directly proportional to the increased levels of CryIA(b) protein in plants transformed with the modified cryIA(b) genes, indicating that the nucleotide sequence of these genes had an effect in improving their translational efficiency in plants.

Purification and characterization of Bacillus thuringiensis var. tenebrionis insecticidal proteins produced in E. coli

Native and single amino acid variants of the Bacillus thuringiensis var. tenebrionis insecticidal proteins were expressed in Escherichia coli, purified and examined for biological and biochemical properties. A novel, pH dependent, preferential precipitation method was implemented to purify Escherichia coli produced Bacillus thuringiensis var. tenebrionis proteins, which are active against Colorado potato beetle (Leptinotarsa decemlineata) larvae. Cysteine residues of the native Bacillus thuringiensis var. tenebrionis protein were replaced by serine residues by site-directed mutagenesis to investigate the biological and structural importance of the individual cysteine residues. Sulfhydryl determination of the native and amino acid variant Bacillus thuringiensis var. tenebrionis proteins revealed that the native protein contains no disulfide bonds. Modification of the carboxyl terminal cysteine residue (amino acid 540) caused complete inactivation of the protein. Native, truncated and single amino acid variants (other than at amino acid 540) exhibited insecticidal activities comparable to each other and to solubilized crystals from the original strain.

Relation of knowledge and performance in boys' tennis: age and expertise

This research examined boys' development of knowledge structure and sport performance in tennis. To assess decision-making and performance, expert and novice tennis players (10-11 and 12-13 years old) were compared on tennis performance (control, decision, and execution), tennis knowledge, serve skill, and groundstroke skill. Experts regardless of age performed better than novices on tennis skill and knowledge; experts' decisions and actions were better during tennis game performance. Declarative knowledge was related to the development of procedural knowledge; serve and groundstroke skill were related to the motor execution components of performance. Interviews during and after game play were used to examine knowledge and decision-making. Experts, as compared to novices, focused on higher level concepts, had more connections between concepts, and had more condition and alternative action concepts that were important to the game's goal structure. Experts' greater decision-making ability during game play was related to their knowledge structure.

Acute fulminant toxoplasma meningoencephalitis in a homosexual man

A homosexual man with a history of sexually transmitted infections including recent giardiasis and high cytomegalovirus (CMV) titer was admitted with generalized weakness, headache, and depression. He rapidly became comatose and developed signs of increased intracranial pressure. CT scan revealed a right cerebral lesion. Pathologic examination disclosed an acute necrotizing granulomatous toxoplasmosis involving the cerebrum. This case represents an example of an opportunistic infection in a male homosexual associated with fulminant clinical course, probably on the basis of immune deficiency.