Neutral and Cationic Bis-Chelate Monoorganosilicon(IV) Complexes of 1-Hydroxy-2-pyridinone

A series of spirocyclic monoorganosilicon compounds of the form RSi(OPO)2Cl [R = phenyl (1); p-tolyl (2); benzyl (3); Me (4); tBu (5); thexyl (6)] (OPO = 1-oxo-2-pyridinone) was synthesized and characterized by 1H , 13C, and 29Si NMR spectroscopy, X-ray crystallography, and elemental analysis. In the solid state, complexes 1, 2, and 3 are neutral and possess cis-OPO ligands in an octahedral arrangement, and complexes 4, 5, and 6 are cationic and possess effectively trans­-OPO ligands in nearly ideal square pyramidal geometries along the Berry-pseudorotation coordinate. In 4-6, chloride dissociation is attributed to the additive effect of multiple intermolecular C—H∙∙∙Cl interactions in their crystals. In DMSO-d6 solution, compounds 1-6 form cationic hexacoordinate DMSO adducts with trans-OPO ligands, all of which undergo dynamic isomerization with energy barriers of ~18-19 kcal/mol. Compounds with better leaving groups, (p-tolyl)Si(OPO)2X [X = I (7); X = triflate (8)], exhibit identical solution NMR spectra as 2, supporting anion dissociation in each. The fluoride derivatives RSi(OPO)2F [R = benzyl (9); Me (10)] exhibit hexacoordinate geometries with cis­-OPO ligands in the solid state and exhibit dynamic isomerization in solution. Overall, these studies indicate, in both the solid and solution states, that the trans-OPO ligand arrangement is favored when anions are dissociated and a cis­-OPO ligand arrangement when anions are coordinated

The Digital Anatomist Information System and Its Use in the Generation and Delivery of Web-Based Anatomy Atlases

Advances in network and imaging technology, coupled with the availability of 3-D datasets such as the Visible Human, provide a unique opportunity for developing information systems in anatomy that can deliver relevant knowledge directly to the clinician, researcher or educator. A software framework is described for developing such a system within a distributed architecture that includes spatial and symbolic anatomy information resources, Web and custom servers, and authoring and end-user client programs. The authoring tools have been used to create 3-D atlases of the brain, knee and thorax that are used both locally and throughout the world. For the one and a half year period from June 1995–January 1997, the on-line atlases were accessed by over 33,000 sites from 94 countries, with an average of over 4000 ‘‘hits’’ per day, and 25,000 hits per day during peak exam periods. The atlases have been linked to by over 500 sites, and have received at least six unsolicited awards by outside rating institutions. The flexibility of the software framework has allowed the information system to evolve with advances in technology and representation methods. Possible new features include knowledge-based image retrieval and tutoring, dynamic generation of 3-D scenes, and eventually, real-time virtual reality navigation through the body. Such features, when coupled with other on-line biomedical information resources, should lead to interesting new ways for managing and accessing structural information in medicine

Plasma functionalization of nano- and micro-sized particles

We demonstrate the controlled chemical functionalization of polymeric and carbon-based particles using two types of table-top plasma technology: These are vacuum and atmospheric-pressure (ambient) polymerization discharges operating in a range of monomers and monomer-gas mixtures. The degree of functionalization is determined using a suite of analytical techniques, such as XPS and FTIR for species identification and zeta potential measurements to determine the surface charge. Two particulate materials are highlighted, mono-dispersive 830 nm polystyrene nanoparticles for applications in drug delivery and graphene platelets for advanced composites. Chemistries deposited include carboxylic acid and amine containing groups. The background of the plasma polymerization methodology for particle modification is discussed

Evaluating A Math Instructors Clarity: An Analysis Of Low-To-Moderate Items Versus A High Inference Item

Instructors and students identify communication skills as being essential to successful classroom teaching and student learning. This study investigates the stability of student evaluations with respect to items related to instructor’s clarity. The majority of student evaluations completed at the end of a semester at the college level contain a question directly related to clarity. A pilot study was conducted which utilized four finite mathematics courses being taught by the same instructor. After assessing reliability and validity, a follow-up study was conducted utilizing four sections of introductory statistics employing the same design as the pilot. Ninety-four students completed some component of the researcher-constructed evaluation resulting in an overall 96% response rate. Seventy-one students completed the entire evaluation, allowing for a comparison between the high inference and the low-to-moderate inference items used to measure instructor’s clarity, resulting in a useable response rate of 72%. After a statistical transformation of the high inference item, descriptive statistics were produced for each type of item. Through a t-test, a statistically significant difference was found between the high and low-to-moderate clarity items. The difference between the types of clarity ratings was then analyzed via ANOVA techniques to explore differences by gender and expected course grade. Males tended to rate the instructor inconsistently, assigning lower ratings for the low-to-moderate inference items, while other ratings appear to demonstrate consistency

Exploring The Reliability, Validity, And Utility Of A Higher Education Faculty Review Process

Institutions of learning face significant calls for accountability, leading to an increased interest in measuring faculty performance. The purpose of this research is to describe and analyze the process of faculty evaluation in a college of education at a southeastern university. The process is outlined with attention given to the reliability, validity, and utility through documenting strengths and weaknesses. Included is a detailed review of the instruments utilized in the process.  Suggestions for improvements and modifications are central to the outcomes, including plans for aligning the process with relevant research.  The degree to which the faculty review process is deemed credible, professional, and relevant may serve as an indicator of the link between theory and practice.  Potential ramifications of a weak or bias system, as faculty promotion and tenure are intertwined with this process, are of utmost importance. Legal issues, including challenges, rise to the forefront.  This topic is of importance to students, faculty, and administrators, as all involved and impacted by the review process, either directly or indirectly.  The applicability of this work beyond the example institution is also addressed

Challenging the Validity of Higher Education Course Evaluations

In higher education, course evaluations are given much attention, with results directly impacting such events as merit review and tenure/promotion. The accurate presentation and proper use of the evaluation results is a critical issue. The typical course evaluation process involves distributing a Likert-type survey to a class, compiling the data and reporting means/standard deviations (classical test theory approach, CTT). One alternative analytical technique is the Rasch model. A theoretical review of each model and an empirical example utilizing end of semester course evaluations from an introductory statistics course taught at a Midwest community college is presented to demonstrate the step-by-step process of feedback via each model. A contention is made that the CTT summary is not producing a valid picture of the evaluation data. The survey research community and institutions analyzing similar rating scale data will benefit from the results of this study as it provides a sound methodology for analyzing such data. The education community will also benefit by receiving better-informed results

Bond Strength of Direct and Indirect Bonded Brackets After Thermocycling

Thermocycling simulates the temperature dynamics in the oral environment. With direct bonding, thermocycling reduces the bond strength of orthodontic adhesives to tooth structure. The purpose of this study was to evaluate the shear bond strengths (SBS) of one direct and two indirect bonding methods/adhesives after thermocycling. Sixty human premolars were divided into three groups. Teeth in group 1 were bonded directly with Transbond XT. Teeth in group 2 were indirect bonded with Transbond XT/Sondhi Rapid Set, which is chemically cured. Teeth in group 3 were indirect bonded with Enlight LV/Orthosolo and light cured. Each sample was thermocycled between 5°C and 55°C for 500 cycles. Mean SBS in groups 1, 2, and 3 were not statistically significantly different (13.6 ± 2.9, 12.3 ± 3.0, and 11.6 ± 3.2 MPa, respectively; P \u3e .05). However, when these values were compared with the results of a previous study using the same protocol, but without thermocycling, the SBS was reduced significantly (P = .001). Weibull analysis further showed that group 3 had the lowest bonding survival rate at the minimum clinically acceptable bond-strength range. The Adhesive Remnant Index was also determined, and group 2 had a significantly (P \u3c .05) higher percentage of bond failures at the resin/enamel interface

A Comparison of Bond Strength Between Direct- and Indirect-bonding Methods

The purpose of this study was to evaluate and compare the shear bond strength and the sites of bond failure for brackets bonded to teeth, using two indirect-bonding material protocols and a direct-bonding technique. Sixty extracted human premolars were collected and randomly divided into three groups. The direct-bonded group (group 1) used a light-cured adhesive and primer (Transbond XT). One indirect-bonded group (group 2) consisted of a chemical-cured primer (Sondhi Rapid Set) and light-cured adhesive (Transbond XT), whereas the other group (group 3) used a light-cured primer (Orthosolo) and adhesive (Enlight LV). Forty hours after bonding, the samples were debonded. Mean shear bond strengths were 16.27, 13.83, and 14.76 MPa for groups 1, 2, and 3, respectively. A one-way analysis of variance showed no significant difference in mean bond strength between groups (P = .21). Furthermore, a Weibull analysis showed all three groups tested provided over a 90% survival rate at normal masticatory and orthodontic force levels. For each tooth, an Adhesive Remnant Index (ARI) score was determined. Group 2 was found to have a significantly lower ARI score (P \u3c .05) compared with groups 1 and 3. In addition, Pearson correlation coefficients indicated no strong correlation between bond strength and ARI score within or across all groups

Interactive Java Tools for Exploring High-dimensional Data

The World Wide Web (WWW) is a new mechanism for providing information. At this point, the majority of the information on the WWW is static, which means it is incapable of responding to user input. Text, images, and video are examples of static information that can easily be included in a WWW page. With the advent of the Java programming language, it is now possible to embed dynamic information in the form of interactive programs called applets. Therefore, it is not only possible to transfer raw data over the WWW, but we can also now provide interactive graphics for displaying and exploring data in the context of a WWW page. In this paper, we will describe the use of Java applets that have been developed for the interactive display of high dimensional data on the WWW