Showing papers by "Wichita State University published in 1998"
TL;DR: In this article, the authors describe version 90 (C90) of the code, paying particular attention to changes in the atomic database and numerical methods that have affected predictions since the last publicly available version, C84.
Abstract: CLOUDY is a large‐scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. Here we describe version 90 (C90) of the code, paying particular attention to changes in the atomic database and numerical methods that have affected predictions since the last publicly available version, C84. The computational methods and uncertainties are outlined together with the direction future development will take. The code is freely available and is widely used in the analysis and interpretation of emission‐line spectra. Web access to the Fortran source for CLOUDY, its documentation Hazy, and an independent electronic form of the atomic database is also described.
2,571 citations
TL;DR: This paper examined the contributions of age and education to adults' epistemological beliefs and found that education predicted beliefs about the structure and stability of knowledge and the speed and control of learning.
Abstract: Background. Individuals' beliefs about the nature of knowledge and learning, or epistemological beliefs, have been linked to their comprehension, meta-comprehension, persistence, and interpretation of information (e.g., Kitchener & King, 1981; Ryan, 1984; Songer & Linn, 1991). Little is known about the development of epistemological beliefs.
Aims. This research examines the contributions of age and education to adults' epistemological beliefs.
Sample. A total of 418 adults from all walks of life (e.g., homemakers, waitresses, teachers, farmers, carpenters, executives, and lawyers) participated in this study. Stratified random sampling was used to ensure that one-third of the sample had only a high school education, another third had some college undergraduate experience, and the other third had some graduate school experience.
Method. Adults completed an epistemological questionnaire that assesses beliefs about the structure and stability of knowledge, and the speed and control of learning.
Results. To ensure that the epistemological questionnaire was suitable for this sample, a factor analysis was carried out. Factor scores that were generated replicated a factor structure that had been found in earlier studies (Dunkle, Schraw & Bendixen, 1993; Schommer, 1990). Results from multiple regression analyses indicated that education predicted beliefs about the structure and stability of knowledge. Age predicted beliefs about the ability to learn.
Conclusions. This evidence suggests that both age and education affect individuals' epistemological beliefs in unique ways. This may have implications for older adults who return to school eager to learn but with misunderstandings about the nature of knowledge, and younger adults who attend school with doubts about the malleability of the ability to learn.
314 citations
TL;DR: The authors investigated consumers' affective attachment toward products, based on generalizable and managerially relevant product attributes, and found that high-involvement, high-meaning products tend to share ten common attributes.
Abstract: This study investigates consumers’ affective attachments toward products, based on generalizable and managerially relevant product attributes. Two surveys of 123 consumers found that high‐involvement, high‐meaning products tend to share ten common attributes. The managerial implications of each attribute are discussed, including specific ways that brand managers and new product development teams can engineer relationships between brands and customers.
191 citations
TL;DR: This study explored the use of the ADHD-IV Rating Scale School Version with male Caucasian and African American students from ages 5 to 18 years and indicated that scale does not perform identically across groups.
Abstract: Behavior rating scales are commonly used in the assessment of attention deficit-hyperactivity disorder (ADHD). However, there is little information available concerning the extent to which scales are valid with culturally different students. This study explored the use of the ADHD-IV Rating Scale School Version with male Caucasian (CA) and African American (AA) students from ages 5 to 18 years. Teachers rated AA students higher on all symptoms across all age groups. LISREL analysis indicated that scale does not perform identically across groups. This was supported by the results of multidimensional scaling with suggested that there is a different relation between items across groups. Implications for research and practice are discussed.
168 citations
TL;DR: In this article, the authors presented new infrared JHK photometry for 61 halo and disk stars around the stellar/substellar boundary and compared the predictions of the latest model atmospheres and structural models.
Abstract: We present new infrared JHK photometry for 61 halo and disk stars around the stellar/substellar boundary. We also present new L' photometry for 21 of these stars and for 40 low-mass stars taken from the Leggett photometry compilation. These data are combined with available optical photometry and astrometric data to produce color-color and absolute magnitude-color diagrams; the current sample extends the similar work presented in the 1992 paper into more metal-poor and lower mass regimes. The disk and halo sequences are compared to the predictions of the latest model atmospheres and structural models. We find good agreement between observation and theory except for known problems in the V and H passbands, probably due to incomplete molecular data for TiO, metal hydrides, and H2O. The metal-poor M subdwarfs are well matched by the models since oxide opacity sources are less important in this case. The known extreme M subdwarfs have metallicities about one-hundredth solar, and the coolest subdwarfs have Teff ~ 3000 K with masses ~0.09M/M☉. The grainless models are not able to reproduce the flux distributions of disk objects with Teff < 2500 K; however, a preliminary version of the NextGen-Dusty models that includes homogeneous formation and extinction by dust grains is able to match the colors of these very cool objects. The least luminous objects in this sample are GD 165B, three DENIS objects—DBD 0205, DBD 1058, and DBD 1228—and Kelu-1. These have Teff ~ 2000 K and are at or below the stellar limit with masses ≤0.075M/M☉. Photometry alone cannot constrain these parameters further since the age is unknown, but published lithium detections for two of these objects (Kelu-1 and DBD 1228) imply that they are young (aged about 1 Gyr) and substellar (mass ≤ 0.06M/M☉).
153 citations
TL;DR: It is revealed that those who reported having musculoskeletal pain were seven times more likely to have some difficulty performing three or more activities listed in the questionnaire, and thorough pain assessment and pain management may be important in the maintenance of independent living.
Abstract: The proportion of people 65 years of age and older who report musculoskeletal pain and physical disability is high. The main objective of this study was to determine whether physical disability was associated with the presence of musculoskeletal pain in a sample of senior citizens. Self-administered questionnaires were sent to a sample of 1306 community-dwelling senior citizens in London, Ontario, Canada between August and October 1995. The questionnaire included questions about pain, difficulty performing activities, depressive symptoms, chronic conditions, and demographic information. A total of 887 seniors completed the questionnaire (70.7% response rate, aged 65–94, 41.2% men, 58.8% women). Logistic regression analysis, without controlling for potential confounding variables, revealed that those who reported having musculoskeletal pain were seven times more likely to have some difficulty performing three or more activities listed in the questionnaire (OR=6.91 95% CI 4.92–9.69). When significant confounding variables were controlled in the analysis, seniors who reported musculoskeletal pain were still three times more likely to have some difficulty with three or more activities (OR=2.93, 95% CI 1.96–4.38). Although no causal relationship can be inferred, thorough pain assessment and pain management may be important in the maintenance of independent living for adults 65 years of age or older.
151 citations
TL;DR: In this paper, the authors show that bank seniority plays an important role in encouraging the formation of ongoing bank/firm relationships, and that making the bank senior improves its incentives to build a relationship with the firm, thereby fulfilling an important function of intermediated debt.
Abstract: This paper brings together two seemingly unrelated branches of the literature that focuses on different aspects of a bank's interaction with its borrowers: the relative priority of bank debt, and the role of banks as "relationship lenders". Specifically, we show that bank seniority plays an important role in encouraging the formation of ongoing bank/firm relationships. Because the bank is senior, it is more able to reap the benefits from its relationship with the firm; because the firm has a relationship with a bank, it is more willing to exert effort, thus reducing the impact of a recession on its prospects. As a result, the firm's ex ante value is enhanced when the bank's debt is senior to that of the firm's other creditors. The intuition behind our model lies in the fact that, when the firm's prospects deteriorate, the most senior claimant first benefits from helping the firm improve its quality, and it is in such states that the true value of relationship lending comes to light. If banks are made junior to other creditors, they may benefit little in bad states from additional investment in the firm, and hence will have little incentive to build relationships that might allow them to determine the value of such an investment. As a result, making the bank senior improves its incentives to build a relationship with the firm, thereby fulfilling an important function of intermediated debt.
143 citations
TL;DR: In this article, the effect of Gurney e aps on two-dimensional airfoils, three-dimensional wings, and a ree ection plane model were investigated, and the results showed that the Gurny e ap improved the maximum lift coefe cient compared to the baseline clean cone guration.
Abstract: The effect of Gurney e aps on two-dimensional airfoils, three-dimensional wings, and a ree ection plane model were investigated. There have been a number of studies on Gurney e aps in recent years, but these studies have been limited to two-dimensional airfoil sections. A comprehensive investigation on the effect of Gurney e aps for a wide range of cone gurations and test conditions was conducted at Wichita State University. A symmetric NACA 0011 and a cambered GA (W)-2 airfoil were used during the single-element airfoil part of this investigation. The GA (W)-2 airfoil was also used during the two-element airfoil study with a 25% chord slotted e ap dee ected at 10, 20, and 30 deg. Straight and tapered ree ection plane wings with natural laminar e ow (NLF) airfoil sections were tested for the three-dimensional wing part of this investigation. A fuselage and engine were attached to the tapered NLF wing for the ree ection plane model investigation. In all cases the Gurney e ap improved the maximum lift coefe cient compared to the baseline clean cone guration. However, there was a drag penalty associated with this lift increase.
127 citations
01 Aug 1998
TL;DR: It is shown that an increase in computation, necessary for the statistical resampling methods, produces networks that perform better than those constructed in the traditional manner.
Abstract: Neural networks must be constructed and validated with strong empirical dependence, which is difficult under conditions of sparse data. The paper examines the most common methods of neural network validation along with several general validation methods from the statistical resampling literature, as applied to function approximation networks with small sample sizes. It is shown that an increase in computation, necessary for the statistical resampling methods, produces networks that perform better than those constructed in the traditional manner. The statistical resampling methods also result in lower variance of validation, however some of the methods are biased in estimating network error.
121 citations
TL;DR: By investigating the form of the HIC functional, it is possible to extract structural information by the computation of the moments of the functional, including the average HIC value, HIC variance, and higher-order HIC moments.
119 citations
TL;DR: In this paper, the general subject of pitfalls of power quality indices is discussed and suggestions for alleviating these problems are made, as well as suggestions for improving the power acceptability curves.
Abstract: Several indices are in common use for the quantification of electric power quality. These indices are convenient for condensing complex time and frequency domain waveform phenomena into a number. However, a variety of commonly encountered circumstances are not readily accommodated (e.g. quasiperiodic and aperiodic signal components and noninteger multiples of the power frequency). Also, the power acceptability curves have been used as convenient measures of power quality and these curves do not capture three-phase detail of power quality problems. In this paper, the general subject of pitfalls of power quality indices is discussed and suggestions for alleviating these problems are made.
TL;DR: Two copper-binding compounds/cofactors were isolated from the spent media of both the wild type and a constitutive soluble methane monooxygenase mutant, PP319, and high concentrations of CBCs were observed in the extracellular fraction of the sMMOC mutants PP319 and PP359 regardless of the copper concentration in the culture medium.
Abstract: Two copper-binding compounds/cofactors (CBCs) were isolated from the spent media of both the wild type and a constitutive soluble methane monooxygenase (sMMO C ) mutant, PP319 (P. A. Phelps et al., Appl. Environ. Microbiol. 58:3701–3708, 1992), of Methylosinus trichosporium OB3b. Both CBCs are small polypeptides with molecular masses of 1,218 and 779 Da for CBC-L 1 and CBC-L 2 , respectively. The amino acid sequence of CBC-L 1 is S?MYPGS?M, and that of CBC-L 2 is SPMP?S. Copper-free CBCs showed absorption maxima at 204, 275, 333, and 356 with shoulders at 222 and 400 nm. Copper-containing CBCs showed a broad absorption maximum at 245 nm. The low-temperature electron paramagnetic resonance (EPR) spectra of copper-containing CBC-L 1 showed the presence of a copper center with an EPR splitting constant between those of type 1 and type 2 copper centers (g ⊥ = 2.087, g ∥ = 2.42 G, ‖A ∥ ‖ = 128 G). The EPR spectrum of CBC-L 2 was more complex and showed two spectrally distinct copper centers. One signal can be attributed to a type 2 Cu 2+ center (g ⊥ = 2.073, g ∥ = 2.324 G, ‖A ∥ ‖ = 144 G) which could be saturated at higher powers, while the second shows a broad, nearly isotropic signal near g ⊥ = 2.063. In wild-type strains, the concentrations of CBCs in the spent media were highest in cells expressing the pMMO and stressed for copper. In contrast to wild-type strains, high concentrations of CBCs were observed in the extracellular fraction of the sMMO C mutants PP319 and PP359 regardless of the copper concentration in the culture medium.
TL;DR: This paper reports a geometric constraint-solving approach based on symbolic computation that can compute robust numerical solutions for a set of equations and give complete methods of deciding whether the constraints are independent and whether a constraint system is over-constraint.
Abstract: This paper reports a geometric constraint-solving approach based on symbolic computation. With this approach, we can compute robust numerical solutions for a set of equations and give complete methods of deciding whether the constraints are independent and whether a constraint system is over-constraint. Based on symbolic computation, we also have a decision procedure for the problem of deciding whether a constrained diagram can be constructed with ruler and compass (rc-constructibility).
TL;DR: It is shown that the simple tuning fuzzy controller with altered scaling factors is well suited for controlling the trajectory of the aircraft in the landing phase which requires simultaneous control of engine thrust for the velocity and elevator for the pitch attitude in order to change altitude with a constant airspeed.
Abstract: A fuzzy logic system is developed for automatic landing control of a transport aircraft. A linear longitudinal aircraft model, with landing gear and flaps deployed at the sea level, is employed for fuzzy logic controller design of automatic landing system including the two landing phases - the glide-path capture and the flare maneuver. In addition, the fuzzy control system is tested using different values of fuzzy controller scaling factors on a six degree of. freedom nonlinear aircraft model. It is shown that the simple tuning fuzzy controller with altered scaling factors is well suited for controlling the trajectory of the aircraft in the landing phase which requires simultaneous control of engine thrust for the velocity and elevator for the pitch attitude in order to change altitude with a constant airspeed.
TL;DR: In this paper, the electronic, spectral, and electrochemical characterization of (meso-tetraphenylporphyrinato)zinc(II) complexes bearing between 0 and 8 bromo substituents at the beta-pyrrole positions is reported.
Abstract: The electronic, spectral, and electrochemical characterization of (meso-tetraphenylporphyrinato)zinc(II) complexes bearing between 0 and 8 bromo substituents at the beta-pyrrole positions is reported. The investigated compounds are represented as (TPPBr(x)())Zn where TPPBr(x)() is the dianion of brominated 5,10,15,20-tetraphenylporphyrin and x varies between 0 and 8. Each porphyrin undergoes four well-defined one-electron transfer reactions to yield porphyrin pi-cation radicals and dications upon oxidation and porphyrin pi-anion radicals and dianions upon reduction. Half-wave potentials for the first reduction of (TPPBr(x)())Zn can be described by a single linear free energy relationship, and plots of E(1/2) versus the number of Br groups on the complex show a linear correlation with a positive slope of 63 mV per Br group. This is not the case for the other three electron transfer processes of the compounds where plots of E(1/2) versus the number of Br groups show distinctly different linear correlations for derivatives with 0-4 Br groups and those with 4-8 Br groups. The effect of increasing number of Br groups on the spectral and electrochemical properties of the neutral complexes was examined over the whole series of compounds, and these experimental results are compared to results of theoretical calculations by semiempirical molecular orbital AM1 methods using configurational interactions (CI) over the four Gouterman frontier pi-orbitals. The dihedral angle containing the four porphyrin macrocycle ring nitrogens is proposed as a measure of porphyrin ring nonplanarity, and this value increases with increasing number of Br substituents on (TPPBr(x)())Zn. Results of the AM1-CI = 4 calculations indicate that the spectrally determined HOMO-LUMO gap, i.e., the energy corresponding to the low-energy absorption band, varies in a nonlinear fashion with increasing number of Br substituents on the macrocycle and this is due to both the electronic effect of the substituents and the macrocycle nonplanarity. The HOMO-LUMO gaps theoretically calculated by AM1-CI = 4 methods thus parallel values which are experimentally obtained by electrochemistry or spectroscopy. The lack of well-defined linear free energy relationships for all processes except for the first reduction can be explained on the basis of electronic effects caused by the halogen substituents and nonplanar macrocyclic distortions induced by steric interactions among the peripheral substituents. In the case of porphyrin dication formation, the redox potentials are virtually independent of the bromo substituents.
TL;DR: In this paper, the authors show that the heat transfer coefficient and pressure drop are functions of the flow qualify mass flux, and, of course, the heat flux and related surface superheat.
Abstract: Microchannel surfaces, often machined to 20 to 1000 μm in width and depth, are employed in high-heat-flux applications. However, a large number of variables control the two-phase flow, heat transfer coefficient. The pressure, the surface heat flux, and the mass flux significantly affect the thermal transport. Experiments were conducted on a setup that was built for testing microchannel heat exchangers, The parameters considered in the study are power input: 20 to 300 W, volume flow rate: 35 to 300 ml/min, quality: 0 to 0.5, inlet subcooling: 5 to 15°C. The results indicate that the heat transfer coefficient and pressure drop are functions of the flow qualify the mass flux, and, of course, the heat flux and the related surface superheat. The heat transfer coefficient decreases from a value of 12,000 W/m 2 -K to 9000 W/m 2 -K at 80°C, when the wall superheat is increased from 10 to 80°C. The coefficient decreases by 30 percent when the exit vapor quality is increased from 0.01 to 0.65.
TL;DR: Generational status was the only measure of accULTuration that consistently predicted wife assaults; however; ethnic-group differences remained after controlling for differences in acculturation level.
Abstract: Existing research has demonstrated that Hispanic Americans as a group exhibit some of the highest rates of violent behavior toward theirspouses. Evidence exists, however; that suggests that these rates vary by Hispanic group identification (e.g., Puerto Rican, Mexican, Mexican American, Cuban). One explanation for these ethnic differences suggests that they may be a result of the process of acculturation. It is also possible that variations in rates of wife assault attibuted to differences in acculturation level may be caused by differences in measures of this concept. This study used the 1992 National Alcohol and Family Violence Survey, a national sample of 1,970 persons, to examine the role of acculturation in both minor and severe wife assault as well as the impact of using different indicators of acculturation. Generational status was the only measure of acculturation that consistently predicted wife assaults; however; ethnic-group differences remained after controlling for differences in acculturatio...
TL;DR: It is suggested that a medication teaching intervention geared to the special needs of the elderly can be effective in increasing medication knowledge.
Abstract: Background Medication adherence by older adults who are discharged from the emergency department (ED) is an essential attribute of effective treatment. Researchers have demonstrated that delivery of well-structured instructions increases the knowledge of discharge regimens and increases adherence among ED populations. Objectives This study compared the level of medication knowledge of elderly ED patients receiving instruction by one of two teaching methods: the usual preprinted discharge instructions with handwritten medication information and individualized computer-generated discharge instructions designed within a geragogy framework. Method The geragogy intervention included large-print, easily readable, specific information ordered within the elderly memory schema. This schema consists of purpose, administration, and emergency information in that order. The Knowledge of Medication Subtest by Horn and Swain (1977) was administered by telephone 48 to 72 hours after discharge. Sixty patients (38 women, 22 men) with a mean age of 76 years were randomly assigned to groups and completed the study at three rural ED sites. Results Subjects in the geragogy-based intervention group demonstrated significantly more knowledge of medications than did subjects experiencing the usual discharge teaching method (t = 2.19, p = .016). Conclusions These findings suggest that a medication teaching intervention geared to the special needs of the elderly can be effective in increasing medication knowledge.
TL;DR: The results of these studies demonstrate that the 1,2,5-thiadiazolidin-3-one 1,1, dioxide platform provides an effective means for appending recognition elements in a well-defined vector relationship, and in fashioning highly-selective and potent inhibitors of serine proteinases.
TL;DR: A series of ruthenium(II) complexes of the types [Ru(bpy)n(dafo)3-n]2+, where n varies between 0 and 3 and dafo is 4,5-diazafluoren-9-one, were synthesized, and their chemical, physical, and photophysical properties were examined as mentioned in this paper.
Abstract: A series of ruthenium(II) complexes of the types [Ru(bpy)n(dafo)3-n]2+ and [Ru(bpy)n(dafo-ketal)3-n]2+, where n varies between 0 and 3 and dafo is 4,5-diazafluoren-9-one, were synthesized, and their chemical, physical, and photophysical properties were examined. The coordinated dafo-ketal ligand readily forms by the direct reaction of [Ru(bpy)n(dafo)3-n]2+ complexes with ethylene glycol or by reaction of the appropriate ruthenium precursors with the correct stoichiometric amount of the dafo ligand in ethylene glycol. In each series, the visible absorption band associated with the MLCT transition shifts to the blue and the electrochemical oxidation associated with the Ru(III)/Ru(II) couple becomes more positive as n decreases. Coordinated dafo undergoes a one-electron reduction at potentials <−1 V and a second one-electron reduction at ∼−1.2 V vs SSCE. The first reduction can be associated with reduction of the carbonyl group; the second, with reduction of the bipyridine portion. Coordinated dafo-ketal onl...
TL;DR: It is concluded that DES is much more potent that E2 as a neonatal endocrine disrupter in the male hamster, and the DES-specific lesions in the adult male reproductive tract may represent a permanently altered androgen responsiveness in the affected target tissues.
Abstract: Prenatal and neonatal exposure to natural and synthetic estrogens induces developmental abnormalities in the male and female reproductive systems in several species. In hamsters, a single injection of diethylstilbestrol (DES) on the day of birth induces teratogenic and neoplastic changes throughout the female reproductive tract, apparently via a direct mechanism. The present study investigated the extent and specificity of this phenomenon in the male reproductive system. Male golden hamsters received injections of DES or estradiol-17beta (E2; 100 microg/ animal) on the day of birth and were then killed at 42 (pubertal) and 90 (adults) days of age. Blood was collected for serum testosterone analysis, and the testes and accessory organs were weighed and examined histologically. At the pubertal stage, testicular and accessory organ weights plus serum testosterone levels were similar in untreated animals and in both groups of estrogen-treated animals. Also at the pubertal stage, initiation of spermatogenesis appeared normal in both groups of estrogen-treated animals. In contrast, 100% of the DES-treated animals (n = 22) but none of the E2-treated animals exhibited multiple lesions in the reproductive tract as adults. These DES-induced lesions included cryptorchidism with the testes attached to the abdominal wall, solid testicular tumors, multiple epididymal cysts, and involution of accessory organs. Spermatogenesis was disrupted in the seminiferous tubules, with no developing germ cells, and the interstitial cells were organized as a sheath around the dysfunctional tubules. The epididymis had an involuted epithelial layer with a preponderance of multi-nucleated cells, and seminal vesicle morphology was also abnormal. These DES-specific alterations were not accompanied by any significant change in circulating testosterone levels. We therefore conclude that 1) DES is much more potent that E2 as a neonatal endocrine disrupter in the male hamster, and 2) the DES-specific lesions in the adult male reproductive tract may represent a permanently altered androgen responsiveness in the affected target tissues.
TL;DR: A geometric constraint solving method/system that takes the declarative description of geometric diagrams or engineering drawings as input and outputs a sequence of steps to construct the diagram with ruler and compass if it succeeds is described.
Abstract: We describe a geometric constraint solving method/system that takes the declarative description of geometric diagrams or engineering drawings as input and outputs a sequence of steps to construct the diagram with ruler and compass if it succeeds. We extend the local propagation to a global one. Like the local propagation, the global propagation tries to determine the position of a geometric object from the set of geometric objects whose positions are already known. However, our global propagation uses not only the constraints involving this object but also implicit information derived from other constraints. The algorithm can be used to build intelligent CAD and interactive computer graphic systems.
TL;DR: Data from the federal On-Line Survey Certification and Reporting system show a small overall increase in the staffing levels for registered nurses, licensed vocational and licensed practical nurses (LVNs/LPNs), and nursing assistants over the 5 years, but there are substantial variations across states and regions.
Abstract: Trends in the average nurse staffing levels are reported for certified nursing facilities in the United States from 1991 through 1995. Data from the federal On-Line Survey Certification and Reporting system show a small overall increase in the staffing levels for registered nurses (RNs), licensed vocational and licensed practical nurses (LVNs/LPNs), and nursing assistants over the 5 years, but there are substantial variations across states and regions. A two-stage least squares panel analysis examined predictors of nurse staff levels in states. States with higher resident case mix levels had higher RN and LVN/LPN hours. States with higher percentages of large facilities had lower RN and LVN/LPN levels and states with higher percentages of for-profit facilities had lower RN staff levels. States with a higher percentage of Medicaid residents had higher LVN/LPN staff levels. These findings indicate the need for more studies of staff variations and public policies that affect staffing.
TL;DR: A variable-temperature emission lifetime study reveals the presence of a low-lying state with DeltaE = approximately 1500 cm(-)(1), and extrapolation to room temperature indicates the emission lifetimes are in the subnanosecond range.
Abstract: A series of bimetallic complexes of ruthenium(II) bridged by heterocyclic ligands formed by the condensation of 4,5-diazafluoren-9-one with various diamines, hydrazine, 1,4-phenylenediamine, benzidine, and 4,4'-methylenedianiline, results in metal centers separated by various distances. The complexes give rise to metal-to-ligand charge-transfer absorptions in the 450 nm region of the visible spectrum and intraligand pi --> pi transitions in the 300 nm region of the ultraviolet spectrum. The ruthenium(II) centers are oxidized in two closely spaced one-electron processes at potentials more positive than that for Ru(bpy)(3)(2+). The bridging ligands are reduced by two closely spaced one-electron processes at more positive potentials than that for reduction of the coordinated bipyridine ligands ( approximately -1.30 V), although the diazafluorene=N-N=diazafluorene bridging ligand is reduced reversibly in two single-electron steps at E(1/2) values of -0.29 and -0.52 V. After purification by eluting the "pure" complexes over a silica gel column with various concentrations of 0.10 M NH(4)PF(6) in methanol, emission occurs only in a glassy matrix at 77 K and at low temperatures in solution. The emission lifetimes at 77 K in a 4:1 ethanol:methanol glass are 5 +/- 1 ms. A variable-temperature emission lifetime study reveals the presence of a low-lying state with DeltaE = approximately 1500 cm(-)(1), and extrapolation to room temperature indicates the emission lifetimes are in the subnanosecond range.
01 Jun 1998
TL;DR: In this article, the results of structure-activity relationship studies in a series of heterocyclic mechanism-based inhibitors based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold I and capable of interacting with the S n and S n − subsites of a serine proteinase were presented.
Abstract: This paper describes the results of structure–activity relationship studies in a series of heterocyclic mechanism-based inhibitors based on the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold I and capable of interacting with the S n and S n ′ subsites of a serine proteinase. Sulfone derivatives of I were found to be highly effective, time-dependent inhibitors of human leukocyte elastase (HLE), cathepsin G (Cat G) and proteinase 3 (PR 3). The judicious selection of an R 1 group (accommodated at the primary specificity site S 1 ) that is based on the known substrate specificity of a target serine proteinase, was found to yield highly selective inhibitors. The presence of a benzyl group (R 2 =benzyl) at the S 2 subsite was found to lead to a pronounced enhancement in inhibitory potency. Furthermore, the effective use of computer graphics and modeling has led to the design of potent, water-soluble inhibitors. The results of these studies demonstrate that the 1,2,5-thiadiazolidin-3-one 1,1, dioxide platform provides an effective means for appending recognition elements in a well-defined vector relationship, and in fashioning highly-selective and potent inhibitors of serine proteinases.
TL;DR: In this paper, the authors have characterized commercially available p-toluenesulfonic acid monohydrate (TsOH) as an efficient catalyst for the intermolecular coupling of the aromatic nucleus with activated alkyl halides, alke.
Abstract: Alkylation of the aromatic nucleus, an important reaction in industry and synthetic organic chemistry, has traditionally been carried out by the well-known Friedel−Crafts reaction employing Lewis acid catalysts such as AlCl3 and BF3 or by using highly reactive organometallic reagents Although protic acids such as anhydrous HF and concentrated H2SO4 have also been used in the alkylation of the aromatic nucleus, the notoriously corrosive, highly toxic, and hazardous nature of these agents has precluded their common use under ordinary laboratory conditions Various organic sulfonic acids have, on occasion, been used as catalysts in Friedel−Crafts alkylations, but to our knowledge the chemistry and the scope of these reactions for common laboratory use have never been exploited in detail In the present study we have characterized commercially available p-toluenesulfonic acid monohydrate (TsOH) as an efficient catalyst for the intermolecular coupling of the aromatic nucleus with activated alkyl halides, alke
12 Jan 1998
01 Dec 1998
TL;DR: In this article, an integrated conceptual model of an adaptive decision support system (ADSS) is proposed by following a unified research methodology, which consists of several components at two levels: the meta-level and the basic-level.
Abstract: An integrated conceptual model of an adaptive decision support system (ADSS) is proposed by following a unified research methodology. Adaptive behaviors of the DSS are identified based on previous research into adaptivity of information systems. A variety of knowledge that enables the system to adaptively behave is recognized. The concept of a reflexive system and a conceptual framework of decision-making organization are adopted to structure various components. This model consists of several components at two levels: the meta-level and the basic-level. The components in the basic-level unit communicate with the user and carry out the task of decision support. The meta-level is a controlling unit capable of introspecting the system's capabilities and limitations, and determining an appropriate action to adjust the capabilities of components in the basic-level unit.
TL;DR: The Peer Group Caring Interaction Scale (PGCIS) as mentioned in this paper is designed to measure caring during informal peer interactions as experienced by undergraduate nursing students, which has two subscales that address caring peer behaviors and interactional events during which students assist their peers in the resolution of specific needs.
Abstract: The purpose of this study was to develop psychometric properties of the Peer Group Caring Interaction Scale (PGCIS) designed to measure caring during informal peer interactions as experienced by undergraduate nursing students. The PGCIS has two subscales that address caring peer behaviors and interactional events during which students assist their peers in the resolution of specific needs. PGCIS psychometric properties were developed using data from 873 junior students enrolled at 87 BSN schools of nursing. Internal consistency reliability was demonstrated for the 9-item Caring Behaviors and the 7-item Giving Assistance subscales with a coefficient alpha of .91 for each. Findings from an exploratory factor analysis supported the two subscale structure of the PGCIS. The PGCIS scores correlated positively with scores on the Intimacy subscale of the Organization Climate Description Questionnaire (OCDQ) and the Peer Group Interaction Scale and inversely with scores on the OCDQ Disengagement subscale. The findings from this study provide beginning support for the PCGIS as a valid and reliable approach to the measurement of caring in academic settings. Additional studies are recommended to continue the psychometric evaluation of this instrument.
TL;DR: Emissions from high energy to low energy are attributed to the following: triplet emission centered on the bph ligand, emission from a dimer (exciplex), emission from an aggregate, and emission from "stacked" platinum(II) crystals.
Abstract: Pt(bph)(CO)2, where bph is the biphenyl dianion, displays multiple emission by altering the temperature, solvent, or its state. Emission spectra and emission quantum yields are concentration and excitation wavelength dependent. In dilute 4:1 ethanol/methanol at room temperature, a structured emission at high energy (∼500 nm) occurs, but in the solid state a nonstructured emission centered at (∼750 nm) is found. Between these extremes, two other emissions located at ∼540 and ∼650 nm are observed. Emissions from high energy to low energy are attributed to the following: triplet emission centered on the bph ligand, emission from a dimer (exciplex), emission from an aggregate, and emission from “stacked” platinum(II) crystals.