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Showing papers by "Wichita State University published in 2005"


Journal ArticleDOI
TL;DR: In this paper, the authors presented a new table for low-temperature Rosseland and Planck mean opacities from Alexander & Ferguson, which includes more grain species and updated optical constants.
Abstract: Previous computations of low-temperature Rosseland and Planck mean opacities from Alexander & Ferguson areupdatedandexpanded.Thenewcomputationsincludeamorecompleteequationofstate(EOS)withmoregrain species and updated optical constants. Grains are now explicitly included in thermal equilibrium in the EOS calculation, which allows for a much wider range of grain compositions to be accurately included than was previously the case. The inclusion of high-temperature condensates such as Al2O3 and CaTiO3 significantly affects the total opacityoveranarrowrangeoftemperaturesbeforetheappearanceofthefirstsilicategrains.Thenewopacitytables are tabulated for temperatures ranging from 30,000 to 500 K with gas densities from 10 � 4 to 10 � 19 gc m � 3 .C omparisons with previous Rosseland mean opacity calculations are discussed. At high temperatures, the agreement with OPAL and Opacity Project is quite good. Comparisons at lower temperatures are more divergent as a result of differences in molecular and grain physics included in different calculations. The computation of Planck mean opacities performed with the opacity sampling method is shown to require a very large number of opacity sampling wavelength points; previously published results obtained with fewer wavelength points are shown to be significantly in error. Methods for requesting or obtaining the new tables are provided. Subject heading gs: atomic data — equation of state — methods: numerical — molecular data

1,273 citations


Journal ArticleDOI
TL;DR: In this article, the authors show that the likelihood of a firm adding a woman to its board in a given year is negatively affected by the number of women already on the board.

1,026 citations


Posted Content
TL;DR: In this paper, the authors examined the valuation effects of the interaction between differences of opinion and short sale constraints and found that stocks are not systematically overvalued when either one of these two conditions is not met.
Abstract: Miller (1977) hypothesizes that dispersion of investor opinion in the presence of short-sale constraints leads to stock price overvaluation. However, previous empirical tests of Miller's hypothesis have examined the valuation effects of only one of these two necessary conditions. We examine the valuation effects of the interaction between differences of opinion and short sale constraints. We find robust evidence of significant overvaluation for stocks that are subject to both conditions simultaneously. Stocks are not systematically overvalued when either one of these two conditions is not met.

445 citations


Journal ArticleDOI
TL;DR: In this paper, a review describes light induced energy or electron transfer reactions in self-assembled supramolecular zinc porphyrin/zinc phthalocyanine and fullerene bearing donor-acceptor systems.

395 citations


Journal ArticleDOI
TL;DR: The study shows how specific IOS decisions allow manufacturing firms to better manage their dependence on the supplier for resources and thereby select system functionalities that are consistent with their own operating environments and the desired supply chain design.
Abstract: Manufacturing firms are increasingly seeking cost and other competitive advantages by tightly coupling and managing their relationship with suppliers. Among other mechanisms, interorganizational systems (IOS) that facilitate boundary-spanning activities of a firm enable them to effectively manage different types of buyer–supplier relationships. This study integrates literature from the operations and information systems fields to create a joint perspective in understanding the linkages between the nature of the IOS, buyer–supplier relationships, and manufacturing performance at the dyadic level. External integration, breadth, and initiation are used to capture IOS functionality, and their effect on process efficiency and sourcing leverage is examined. The study also explores the differences in how manufacturing firms use IOS when operating under varying levels of competitive intensity and product standardization. In order to test the research models and related hypothesis, empirical data on buyer–supplier dyads is collected from manufacturing firms. The results show that only higher levels of external integration that go beyond simple procurement systems, as well as who initiates the IOS, allow manufacturing firms to enhance process efficiency. In contrast, IOS breadth and IOS initiation enable manufacturing firms to enhance sourcing leverage over their suppliers. In addition, firms making standardized products in highly competitive environments tend to achieve higher process efficiencies and have higher levels of external integration. The study shows how specific IOS decisions allow manufacturing firms to better manage their dependence on the supplier for resources and thereby select system functionalities that are consistent with their own operating environments and the desired supply chain design.

359 citations


Journal ArticleDOI
TL;DR: In this article, the authors employed one or two L-shape arrays to remove the problem of pair matching between the 2-D azimuth and elevation angle estimation in the propagator method.
Abstract: It is known that computational loads of the propagator method (PM) can be significantly smaller, e.g., one or two order, than those of MUSIC and ESPRIT because the PM does not require any eigenvalue decomposition (EVD) of the cross-correlation matrix and singular value decomposition (SVD) of the received data. However, the PM of the parallel shape array has nonnegligible drawbacks such as 1) requirement of pair matching between the 2-D azimuth and elevation angle estimation which is an exhaustive search and 2) estimation failure problems when elevation angles are between 70/spl deg/ and 90/spl deg/. The purpose of this paper is to show a way to remove these problems in the PM without additional computational loads. This paper will employ one or two L-shape arrays because the parallel shape used in the PM may cause the aforesaid problems. Simulation results verify that the PM with one or two L-shape configurations can remove these problems and improve the performance of the PM significantly, e.g., almost 5 dB in signal to noise ratio for the parameters used in this paper.

293 citations


Journal ArticleDOI
TL;DR: Ineffective maternal discipline and the interaction of ineffective discipline and hostile attribution predicted growth in child conduct problems at home during kindergarten and first grade.
Abstract: Data were collected in a longitudinal study of 134 boys and 132 girls and their families during kindergarten and first grade. Four hours of parent-child interaction were coded to ascertain parent discipline practices. A structured interview assessed maternal attributions about child behavior. Maternal ratings of child conduct problems at kindergarten entry reliably predicted the mother's subsequent hostile attributions concerning child misbehavior and use of ineffective discipline tactics. Ineffective maternal discipline and the interaction of ineffective discipline and hostile attribution predicted growth in child conduct problems at home during kindergarten and first grade. Changes in teacher-reported and observed child conduct problems at school during kindergarten and first grade were predicted by growth in conduct problems at home and by the interaction of ineffective discipline and hostile attribution.

235 citations


Journal ArticleDOI
TL;DR: In this article, the authors report on the effectiveness and focus of academic self-management interventions for children and adolescents with emotional and behavioral disorders and report that self-monitoring interventions were the predominant type of selfmanagement technique used by researchers.
Abstract: The purpose of this review was to report on the effectiveness and focus of academic self-management interventions for children and adolescents with emotional and behavioral disorders. Twenty-two studies published in 20 articles and involving 78 participants met inclusionary criteria. The overall mean effect size (ES) across those studies was 1.80 (range –0.46 to 3.00), indicating effects were generally large in magnitude and educationally meaningful. Self-monitoring interventions were the predominant type of self-management technique used by researchers. The mean ES for intervention types were self-evaluation (1.13), self-monitoring (1.90), strategy instruction techniques (1.75), self-instruction techniques (2.71), and multiple-component interventions (2.11). Interventions targeted improvement in math calculation skills more than any other area. The mean ES by academic area were math interventions (1.97), writing (1.13), reading (2.28), and social studies (2.66). There was evidence to support a claim of the generalization and maintenance of findings. Implications, limitations, and areas for future research are discussed.

225 citations


Posted Content
TL;DR: In this paper, the authors examined whether environmental and internal team factors influence the stability of emerging venture teams, as well as whether team stability has an impact on firm performance, and found that turnover rates are the result of both external environmental and team composition factors.
Abstract: This study examines whether environmental and internal team factors influence the stability of emerging venture teams, as well as whether team stability (or instability) has an impact on firm performance.Another purpose is to determine whether the effects of adding or dropping team members depend on environmental dynamism and the firm's development stage. The first several hypotheses suggest that firms with large, heterogeneous initial teams are more likely to experience additions and departures, as are firms in a later stage of development and faced with industry dynamism.While team departures are expected to impair performance and additions are expected to improve it, the relationship between turnover and performance is expected to be moderated by task environment dynamism and the organizational development stage.Data from a longitudinal study of 408 emerging firms in Sweden and from a cross-sectional study examining the first five years of 124 new enterprises in the Rocky Mountain Region of the United States are used to test these hypotheses. The results are largely supportive of the hypotheses and lead to the conclusion that new firms benefit from large initial teams.Findings also suggest that turnover rates are the result of both external environmental and team composition factors. (SAA)

216 citations


Journal ArticleDOI
TL;DR: The relationship of deviant talk and role taking during peer interaction, association with deviant peers, and growth in overt and covert conduct problems during kindergarten and first grade were examined in a community sample of 267 boys and girls as discussed by the authors.
Abstract: The relationships of deviant talk and role taking during peer interaction, association with deviant peers, and growth in overt and covert conduct problems during kindergarten and first grade were examined in a community sample of 267 boys and girls. At entry to kindergarten, high levels of overt and covert conduct problems predicted association with deviant peers, and deviant peer association predicted deviant talk and role taking during peer interaction during kindergarten. Association with deviant peers, and deviant talk and role taking predicted growth in overt and covert conduct problems on the playground, in the classroom, and at home during kindergarten and first grade. Peer processes associated with growth in conduct problems that escalate rapidly during late childhood and adolescence appear to occur in earlier childhood. These peer processes may play a central role in the evolution of conduct problems to include covert as well as overt forms.

180 citations


Journal ArticleDOI
TL;DR: The results show that the EUCS is a valid and robust instrument in the Web environment but that one of the subfactors, timeliness, will need further refinement in the future.
Abstract: The purpose of this study is to revise and revalidate the End-User Computing Satisfaction (EUCS) instrument to measure satisfaction with a Web site from a usability perspective. This study is especially important given the increased significance of the Web and the uniqueness of the Web as a computing environment. A total of 176 students participated in a lab simulation that involved a usability evaluation of the Lands' End Web site (http://www.landsend.com). Students were asked to complete a set of tasks, record their answers, and then complete the EUCS instrument. Confirmatory factor analysis and invariance analyses were conducted to test the reliability, validity, and generalizability of the revised EUCS. The results show that the EUCS is a valid and robust instrument in the Web environment but that one of the subfactors, timeliness, will need further refinement in the future. Usability practitioners can use the EUCS to measure end-user satisfaction with a Web site and use the feedback for improving Web-site design. We describe a case study of an actual usability application that utilized the revised EUCS effectively to support the design of building supply Web sites involving two types of end users, homeowners and contractors. We also propose a typology that researchers can use as a starting point to judge when it is necessary to revalidate an instrument like the EUCS. Finally, we discuss the limitations of our study and present avenues for future research.

Journal ArticleDOI
TL;DR: An interactive and contextual model for developing and sustaining community-university partnerships is proposed that includes the potential challenges that might threaten the partnership, such as resource inequality and time commitment.
Abstract: Community-university partnerships for research and action are at the heart of many fields in the social sciences including public health, urban planning, education, and community psychology. These partnerships involve individuals from different backgrounds and disciplines working together to address social issues of importance to the community. This article proposes an interactive and contextual model for developing and sustaining community-university partnerships. The phases in the model include gaining entry into the community, developing and sustaining a mutual collaboration (developing trust and mutual respect, establishing adequate communication, respecting human diversity, establishing a culture of learning, respecting the culture of the setting and the community, and developing an action agenda), and recognizing the benefits and outcomes of partnership work. The model also includes the potential challenges that might threaten the partnership, such as resource inequality and time commitment.

Journal ArticleDOI
TL;DR: The ability to make the transition from unsuccessful to successful management of stuttering was associated with six recurring themes of: support, support, successful therapy, self therapy and behavioral change, cognitive change, utilization of personal experience, and high levels of motivation/determination.

Journal ArticleDOI
TL;DR: The data presented here suggest that the four periplasmic isomerases are not essential for growth under laboratory conditions but may have significant roles in survival in environmental and pathogenic niches, as indicated by the effect on pilus production.
Abstract: In Escherichia coli, FkpA, PpiA, PpiD, and SurA are the four known periplasmic cis-trans prolyl isomerases. These isomerases facilitate proper protein folding by increasing the rate of transition of proline residues between the cis and trans states. Genetic inactivation of all four periplasmic isomerases resulted in a viable strain that exhibited a decreased growth rate and increased susceptibility to certain antibiotics. Levels of the outer membrane proteins LamB and OmpA in the quadruple mutant were indistinguishable from those in the surA single mutant. In addition, expression of P and type 1 pili (adhesive organelles produced by uropathogenic strains of E. coli and assembled by the chaperone/usher pathway) were severely diminished in the absence of the four periplasmic isomerases. Maturation of the usher was significantly impaired in the outer membranes of strains devoid of all four periplasmic isomerases, resulting in a defect in pilus assembly. Moreover, this defect in pilus assembly and usher stability could be attributed to the absence of SurA. The data presented here suggest that the four periplasmic isomerases are not essential for growth under laboratory conditions but may have significant roles in survival in environmental and pathogenic niches, as indicated by the effect on pilus production.

Journal ArticleDOI
TL;DR: The results show that firms with high electronic commerce competence exhibit superior performance and that customer value generated through Web site functionality partially mediates this relationship.
Abstract: The advent of electronic commerce has induced many organizations to develop a Web presence and exploit the opportunities offered by the Internet. In an environment that commoditizes products and allows for easy imitative behavior through instant access to information on competitor's offerings, it is not clear how to build a sustainable competitive advantage. This study endeavors to facilitate an understanding of this complex issue. Electronic commerce competence is posited as a key driver of organizational performance, and it is argued that this effect is mediated by the generation of "customer value" through Web site functionality. By empirically analyzing primary and secondary data from over 100 companies, the relationship between electronic commerce competence, customer value, and both short- and long-term firm performance is examined. The results show that firms with high electronic commerce competence exhibit superior performance and that customer value generated through Web site functionality partially mediates this relationship. In addition, the results show that companies can enhance short-term performance by providing value to the customer in prepurchase situations. But in order to build customer loyalty and thus long-term performance, companies need to enhance the product ownership experience of customers.

Journal ArticleDOI
TL;DR: Changing expectations about the development of new pet–family relationships and the provision of postadoption services might help adopters tolerate the adjustment period and handle problems without resorting to returning the animal.
Abstract: The return of a recently adopted companion animal places the nonhuman animal in jeopardy and may be painful and frustrating to the humans involved. However, if returners learn from the failed adoption experience, future adoptions may be more satisfactory for all concerned. In this study, 78 people who had adopted and returned dogs or cats to an animal shelter in a U.S. Midwestern city were interviewed regarding their reasons for return, reactions to the experience, and plans for future adoptions. Although some returners adjusted their pet ownership plans in potentially beneficial ways, most reacted by counseling greater forethought and planning before adopting. The last, although sound advice, had little to do with reasons for return, which primarily were problems that arose postadoption: pet behavior such as not getting along with other pets or children. Changing expectations about the development of new pet-family relationships and the provision of postadoption services might help adopters tolerate the adjustment period and handle problems without resorting to returning the animal.

Journal ArticleDOI
TL;DR: The authors examined the cross-sectional effects of idiosyncratic risk and dispersion of beliefs while controlling for short-sale constraints, and found that when short sale constraints are present, increased analyst dispersion and idiosyncratic volatility produce negative abnormal returns, consistent with Miller (1977).
Abstract: Merton (1987) predicts that idiosyncratic risk should be priced when investors hold sub-optimally diversified portfolios, but empirical research has not been supportive of the theory. An overlooked assumption in Merton (1987) is that the predictions are predicated on frictionless markets, and in particular an absence of short-sale constraints. We examine the cross-sectional effects of idiosyncratic risk (and dispersion of beliefs) while controlling for short-sale constraints. We find that when short-sale constraints are absent, both idiosyncratic risk and dispersion of analyst forecasts are positively correlated with future abnormal returns; a result consistent with Merton (1987). However, when short-sale constraints are present the correlation becomes negative: increased analyst dispersion and idiosyncratic volatility produce negative abnormal returns, consistent with Miller (1977). This can explain the inconsistent empirical findings in the previous literature, which casts Merton (1987) and Miller (1977) as competing hypotheses.

Journal ArticleDOI
TL;DR: In this article, the authors empirically examined several models with B2B e-commerce overall use as the dependent variable and innovation characteristics, context, channel factors, and organizational structure as the predictor variables.

Journal ArticleDOI
TL;DR: Early sibling conflict and coparticipation in deviant activities synergistically increased the risk for younger siblings' adolescent adjustment problems, and empirical relations held in the context of parental discipline of younger siblings during adolescence.
Abstract: Access full text below in the “Files in this item” section. You can also access it by clicking on the DOI link below.

Journal ArticleDOI
TL;DR: The authors present a model that explains how subordinates perceive the power of their supervisors and the causal mechanisms by which these perceptions translate into subordinate outcomes.
Abstract: The authors present a model that explains how subordinates perceive the power of their supervisors and the causal mechanisms by which these perceptions translate into subordinate outcomes. Drawing on identity and resource-dependence theories, the authors propose that supervisors have power over their subordinates when they control resources needed for the subordinates' enactment and maintenance of current and desired identities. The joint effect of perceptions of supervisor power and supervisor intentions to provide such resources leads to 4 conditions ranging from highly functional to highly dysfunctional: confirmation, hope, apathy, and progressive withdrawal. Each of these conditions is associated with specific outcomes such as the quality of the supervisor-subordinate relationship, turnover, and changes in the type and centrality of various subordinate identities.

Posted Content
TL;DR: In this article, the effect of Ricianness on the capacity of multiple antenna systems is investigated under the assumption that channel state information (CSI) is available only at the receiver, and the exact capacity is given for the former case while capacity bounds are derived for the latter case.
Abstract: The effect of Rician-ness on the capacity of multiple antenna systems is investigated under the assumption that channel state information (CSI) is available only at the receiver. The average-power-constrained capacity of such systems is considered under two different assumptions on the knowledge about the fading available at the transmitter: the case in which the transmitter has no knowledge of fading at all, and the case in which the transmitter has knowledge of the distribution of the fading process but not the instantaneous CSI. The exact capacity is given for the former case while capacity bounds are derived for the latter case. A new signalling scheme is also proposed for the latter case and it is shown that by exploiting the knowledge of Rician-ness at the transmitter via this signalling scheme, significant capacity gain can be achieved. The derived capacity bounds are evaluated explicitly to provide numerical results in some representative situations.

Journal ArticleDOI
TL;DR: In this paper, a more complete equation of state with more grain species and updated optical constants is presented, which allows for a much wider range of grain compositions to be accurately included than was previously the case.
Abstract: Previous computations of low temperature Rosseland and Planck mean opacities from Alexander & Ferguson (1994) are updated and expanded. The new computations include a more complete equation of state with more grain species and updated optical constants. Grains are now explicitly included in thermal equilibrium in the equation of state calculation, which allows for a much wider range of grain compositions to be accurately included than was previously the case. The inclusion of high temperature condensates such as Al$_2$O$_3$ and CaTiO$_3$ significantly affects the total opacity over a narrow range of temperatures before the appearance of the first silicate grains. The new opacity tables are tabulated for temperatures ranging from 30000 K to 500 K with gas densities from 10$^{-4}$ g cm$^{-3}$ to 10$^{-19}$ g cm$^{-3}$. Comparisons with previous Rosseland mean opacity calculations are discussed. At high temperatures, the agreement with OPAL and Opacity Project is quite good. Comparisons at lower temperatures are more divergent as a result of differences in molecular and grain physics included in different calculations. The computation of Planck mean opacities performed with the opacity sampling method are shown to require a very large number of opacity sampling wavelength points; previously published results obtained with fewer wavelength points are shown to be significantly in error. Methods for requesting or obtaining the new tables are provided.

Journal ArticleDOI
TL;DR: In this article, the influence of the spherical clearance joints in spatial multibody systems is assessed based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces.
Abstract: This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.Copyright © 2005 by ASME

Journal ArticleDOI
TL;DR: Job rotation was used mainly to reduce exposure to risk factors for work-related injuries and to reduce work related injuries, whereas supervisor decisions and ergonomic analyses were used to select jobs for the rotation scheme.
Abstract: Job rotation has been advocated as a suitable intervention to control work-related musculoskeletal disorders. However, little is known regarding the prevalence of job rotation, methods used to identify jobs for rotation or the benefits or limitations of job rotation. A web-based questionnaire was developed to survey job rotation practices from Midwest US manufacturing companies. Results indicated that 42.7% of the companies contacted used job rotation, where the median time for which they had used job rotation was 5 years. Job rotation was used mainly to reduce exposure to risk factors for work-related injuries and to reduce work related injuries, whereas supervisor decisions and ergonomic analyses were used to select jobs for the rotation scheme. Major limitations to successful implementation of job rotation included rotation of individuals with medical restrictions, decreased product quality and lack of jobs to rotate to. These findings suggest that further study is needed to determine if exposure to ri...

Journal ArticleDOI
TL;DR: In this article, the authors investigated how driving performance of young and old participants is affected by visual and auditory secondary tasks on a closed driving course and found that cognitive aging was the best predictor of the declines seen in driving performance under dual task conditions.
Abstract: Purpose. This study investigated how driving performance of young and old participants is affected by visual and auditory secondary tasks on a closed driving course. Methods. Twenty-eight participants comprising two age groups (younger, mean age = 27.3 years; older, mean age = 69.2 years) drove around a 5.1-km closed-road circuit under both single and dual task conditions. Measures of driving performance included detection and identification of road signs, detection and avoidance of large low-contrast road hazards, gap judgment, lane keeping, and time to complete the course. The dual task required participants to verbally report the sums of pairs of single-digit numbers presented through either a computer speaker (auditorily) or a dashboard-mounted monitor (visually) while driving. Participants also completed a vision and cognitive screening battery, including LogMAR visual acuity, Pelli-Robson letter contrast sensitivity, the Trails test, and the Digit Symbol Substitution (DSS) test. Results. Drivers reported significantly fewer signs, hit more road hazards, misjudged more gaps, and increased their time to complete the course under the dual task (visual and auditory) conditions compared with the single task condition. The older participants also reported significantly fewer road signs and drove significantly more slowly than the younger participants, and this was exacerbated for the visual dual task condition. The results of the regression analysis revealed that cognitive aging (measured by the DSS and Trails test) rather than chronologic age was a better predictor of the declines seen in driving performance under dual task conditions. An overall z score was calculated, which took into account both driving and the secondary task (summing) performance under the two dual task conditions. Performance was significantly worse for the auditory dual task compared with the visual dual task, and the older participants performed significantly worse than the young subjects. Conclusions. These findings demonstrate that multitasking had a significant detrimental impact on driving performance and that cognitive aging was the best predictor of the declines seen in driving performance under dual task conditions. These results have implications for use of mobile phones or in-vehicle navigational devices while driving, especially for older adults.

Journal ArticleDOI
TL;DR: This paper presents a toll pricing framework by which a traffic planner might find the most appropriate toll vector given certain restrictions and objectives on the network, and derives the toll sets and illustrates the toll Pricing framework for specific instances of the general variable demand models.
Abstract: In this paper, we present a toll pricing framework for a general variable demand traffic assignment problem with side constraints, where the demand between an origin destination pair is a function of the least total travel cost for making the trip. This general demand model unifies earlier toll pricing treatments of the variable demand models including elastic demand traffic assignment problems and combined distribution assignment problems. All of these models have the constant toll revenue property. Given that users experience the side constraints, we show that when they are charged by a toll vector in the first best toll set, the system optimal flows and demands are achieved. We then present a toll pricing framework by which a traffic planner might find the most appropriate toll vector given certain restrictions and objectives on the network. Finally, we derive the toll sets and illustrate the toll pricing framework for specific instances of the general variable demand models.

Journal ArticleDOI
TL;DR: In this article, a stable porphyrin-fullerene conjugate with defined distance and orientation was formed using a newly developed two-point binding strategy involving axial-coordination and cation-crown ether complexation.

Journal ArticleDOI
TL;DR: The ligand 2,6-dimethylphenylisocyanide (CNx) forms six complexes of the formula [Re(CO)3(CNx)(L)]+, where L = 1,10-phenanthroline, and the lowest-energy absorption peaks of the complexes red-shift in the order 1 < 2 < 3 < 4 < 5 < 6.
Abstract: The ligand 2,6-dimethylphenylisocyanide (CNx) forms six complexes of the formula [Re(CO)3(CNx)(L)]+, where L = 1,10-phenanthroline (1), 5-chloro-1,10-phenanthroline (2), 5-nitro-1,10-phenanthroline (3), 5-methyl-1,10-phenanthroline (4), 5,6-dimethyl-1,10-phenanthroline (5), and 1,10-phenanthrolinopyrrole (6). The lowest-energy absorption peaks of the complexes red-shift in the order 1 < 2 < 3 < 4 < 5 < 6. The time-dependent density functional theory (TDDFT) and conductor-like polarizable continuum model (CPCM) computed singlet excited states in ethanol deviate by 1000 cm-1 or less from the experimental UV−vis peaks. The complexes undergo reversible reductions and irreversible oxidations. The electronic energy gap increases in the order 3 < 2 < 1 < 4 < 5 < 6, which is the order of increasing electron-donating power of the phen substituents. The reduction potentials linearly correlate with the B3LYP calculated LUMO energies for 1−6. The complexes emit at room temperature and at 77 K except 3, which emits on...

Journal ArticleDOI
TL;DR: Two types of structurally well-defined, self-assembled zinc porphyrin-fullerene conjugates were formed by "two-point" binding strategies to probe the effect of axial ligation or pi-pi-type interactions on the photochemical charge stabilization in the supramolecular dyads.
Abstract: Two types of structurally well-defined, self-assembled zinc porphyrin-fullerene conjugates were formed by "two-point" binding strategies to probe the effect of axial ligation or pi-pi-type interactions on the photochemical charge stabilization in the supramolecular dyads. To achieve this, meso-tetraphenylporphyrin was functionalized to possess one or four [18]crown-6 moieties at different locations on the porphyrin macrocycle while fullerene was functionalized to possess an alkyl ammonium cation, and a pyridine or phenyl entities. As a result of the crown ether-ammonium cation complexation, and zinc-pyridine coordination or pi-pi-type interactions, stable zinc porphyrin-fullerene conjugates with defined distance and orientation were formed. Evidence for the zinc-pyridine complexation or pi-pi-type interactions was obtained from the spectral and computational studies. Steady-state and time-resolved emission studies revealed efficient quenching of the zinc-porphyrin singlet excited state in these dyads, and the measured rates of charge separation, k(CS) were found to be slightly better in the case of the dyads held by axial coordination and crown ether-cation complexation. Nanosecond transient absorption studies provided evidence for the electron transfer reactions, and these studies also revealed charge stabilization in these dyads. The lifetimes of the radical ion pairs were found to depend upon the type of porphyrins utilized to form the dyads, that is, porphyrin possessing the crown ether moiety at the ortho position of one of the phenyl rings yielded prolonged charge stabilized states. Addition of pyridine to the supramolecular dyads eliminated the zinc-pyridine coordination or pi-pi-type interactions of the "two-point" bound systems due to the formation of a new zinc-pyridine axial bond thus giving a unique opportunity to probe the effect of axial coordination or pi-pi interactions on k(CS) and k(CR). Under these conditions, the measured electron transfer rates revealed faster k(CS) and slower k(CR) as compared to those obtained in the absence of added pyridine. The evaluated lifetimes of the radical ion-pairs were found to be hundreds of nanoseconds and were longer in the presence of pyridine.

Journal ArticleDOI
TL;DR: This descriptive study explored the experiences of patients and partners with return to sexual activity post-ICD implantation to further understand the experience of ICD discharge with sexual activity and to develop educational strategies.