The purpose of this study was to determine the effects of segmentation on immediate and delayed recall and transfer in a multimedia learning environment. The independent variables of segmentation and non-segmentation, and immediate and delayed assessments were manipulated to assess the effects of segmentation on the participants' ability to recall and transfer information from the multimedia tutorial. Data was analyzed using a 2X2 factorial design. The results of this study found that segmentation of multimedia tutorials did not result in significant differences in recall or transfer. The results also revealed that the time period between when a tutorial was viewed and when the recall and transfer assessments were taken did significantly affect participants ability to recall and transfer information. / Ph. D.

The major focus of the research in our laboratory is the investigation of the role of the nitrogenase component, theMoFe protein, in the catalytic mechanism of biological nitrogen fixation. This dissertation research centers on the role(s) of the P cluster, one of the two unique FeS clusters of the MoFe protein, in the electron transfer mechanism of nitrogenase. Prior to the solution of the x-ray crystal structure of the Azotobacter vinelandii MoFe protein, it was had been determined which of the highly conserved cysteinyl residues of this protein were likely P cluster ligands. After elucidation of the crystal structure, it became evident that cysteine-88 of the a-subunit (a-Cys88) and cysteine-95 of the b-subunit (b-Cys95) could play important roles in maintaining and/or perturbing the conformation of the double-cubane structure by virtue of their bridging positions. It was found that three out of ten bacterial strains with substitutions at the a-Cys88 ligand retained significant catalytic activity. We investigated the effects of these substitutions on the overall structural, kinetic and spectroscopic parameters. The results of prior studies suggested a role for the P clusters in accepting, storing, and then delivering the electrons received from the Fe protein. Therefore, we asked whether a-Cys88 substitution resulted in perturbed functioning of the overall catalytic mechanism and more importantly what these differences reveal about the normal mechanism of nitrogenase. Alterations in the bridging cysteine a-88 affected the rate of substrate reduction which can be explained in part by production of cluster-less MoFe protein. Electron flux, NaCl concentration, and reductant concentration titration assays revealed a significant uncoupling of the ATP hydrolysis rate from the substrate reduction rate in the a-88Cys-to-Gly MoFe protein. Rapid kinetic analysis revealed decreased electron tranfer rates in all three of the a-Cys88 altered MoFe proteins when compared to the wild-type MoFe protein. The intermolecular electron transfer rate was lowered in the a-88Cys-to-Asp MoFe protein, while the intramolecular electron transfer rate was limiting in the a-88Cys-to-Gly and a-88Cys-to-Thr MoFe proteins. These results indicated a role for the a-88 position in controlling electron flow through the P cluster. Another significant finding centers on the spectroscopic signals derived from one of these a-88Cys substituted MoFe proteins. The a-88Cys-to-Gly MoFe protein possesses a unique S=1/2 EPR signal in the native, dithionite-reduced state that was shown to be due to a one-electron-oxidized P cluster. This new paramagnetic center was evidence for the dramatic perturbation of the electromagnetic properties of the P cluster by the a-88Cys-to-Gly substitution. Additionally, both Mössbauer and magnetic circular dichroism spectroscopies have also demonstrated significant changes in the electromagnetic environments of the P clusters of these a-88Cys altered MoFe proteins and that each substitution affected the P cluster differently. The novel EPR signal was exploited in order to follow the sequence of electron transfer events in the nitrogenase reaction. Finally, altered nitrogenase component proteins were combined and analyzed in an attempt to distinguish which particular step(s) are perturbed in the overall enzymatic reaction. / Ph. D.

The majority of the research conducted to date on transfer student academic success compares transfer students with first-year freshmen or native students (Belcheir, 1999, 2001; Carlan, 2001; Cohen & Brawer, 1987; Cope & Hannah, 1975; Eimers & Mullen, 1997; Glass & Harrington, 2002; Keeley & House, 1993; Lorentz & Benedict, 1996; Lunneborg & Lunneborg, 1976; Miville & Sedlacek, 1995; Owen, 1991; Pascarella, 1999; Richman, 1979). Of the studies solely focusing on transfer student academic success, there is inconsistency in the variables selected for analysis and in the findings. Furthermore, transfer students from other four-year institutions are often excluded from these studies. The research generally focuses on transfers from a single community college (Townsend, McNerny, & Arnold, 1993) and oftentimes on transfers from a state's public community college system into the state's public university system (Graham & Hughes, 1994; Holton, 1991; Minear, 1998; Walker, 1992). There is a need for research that looks at transfer students from both two- and four-year institutions and that examines multiple variables associated with academic success. The purpose of this study was to determine the value of the following factors in predicting the academic success of undergraduate transfer students in their first and second semesters of enrollment: (a) on-campus residency, (b) ethnicity, (c) gender, (d) domicile (in v. out of state, (e) Scholastic Aptitude Test (SAT) scores, (f) number of credits enrolled in, (g) academic college, (h) class standing, and (i) last prior institution (two-year v. four-year). First semester GPA was included as an additional independent variable in the examination of second semester GPA. The data analyzed in the study were collected in 2002 at a research institution in the mid-Atlantic region and were accessed through the student census file. Participants were students coded as entering undergraduate transfer students in the university's student census file during the fall of 2002. This study defined academic success as first and second semester Grade Point Average (GPA), which were used as dependent variables. The above factors were used as independent variables in a step-wise regression analysis. The results indicated nine significant predictors of first semester GPA. The following variables contributed positively to first semester GPA: (a) SAT scores, (b) class standing, (c) being a student in the College of Architecture and Urban Studies, and (d) attending Community College (CC) #3. The following variables contributed negatively to first semester GPA: (a) attending CC #1, (b) being Black, (c) attending CC #2, (d) attending Comprehensive University #1, and (e) attending CC #4. The only significant predictor of second semester GPA was first semester GPA. This suggests that the first semester predictor variables help set a student up for academic success or failure. That tracking then carries over generally to second semester. / Master of Arts

Associate in Applied Science (AAS) degree graduates often enter the workforce immediately upon graduation. This study examined the vertical transfer decision-making processes of these students as they considered whether to enter the workforce upon graduation or transfer to a four-year university in search of an applied engineering degree. The researcher gathered data from eight community college students in the second half of their two-year industrial trades degree program to understand how their perceptions of academic and social influences affected their post-graduation plans. Results indicated that academic influences, social influences, graduate choices and student self-efficacy had the greatest impact on transfer decisions. The findings suggested that community colleges should improve student knowledge of AAS degree transfer options, with particular focus on faculty advisement. Universities and other stakeholders also have responsibility to ensure AAS graduates perceive four-year program options as advantageous in meeting their career goals.

No description available.

Yes

In dem vom Bundesministerium für Bildung und Forschung über den Projektträger VDI/VDE-IT geförderten Vorhaben "Wirksamkeitsbeurteilung von Transferformen zwischen Wissenschaft und Wirtschaft für die Branchen Produktionstechnik, Umwelttechnologie und Materialforschung" wurden unterschiedliche Formen und Wege des Wissens- und Technologietransfers zwischen Wissenschaft und Wirtschaft analysiert und beschrieben, um Erfolgsmuster für deren Zusammenarbeit aufzuspüren.

In dem vom Bundesministerium für Bildung und Forschung über den Projektträger VDI/VDE-IT geförderten Vorhaben "Wirksamkeitsbeurteilung von Transferformen zwischen Wissenschaft und Wirtschaft für die Branchen Produktionstechnik, Umwelttechnologie und Materialforschung" wurden unterschiedliche Formen und Wege des Wissens- und Technologietransfers zwischen Wissenschaft und Wirtschaft analysiert und beschrieben, um Erfolgsmuster für deren Zusammenarbeit aufzuspüren.:Inhalt Vorstellung des Forschungsvorhabens ..........................................3 Kapitel 1: Feldstudie ...................................................................7 1.1 Vorgehensweise ..........................................................7 1.2 Befragungsergebnisse ................................................8 1.2.1 Ergebnisse der Unternehmensbefragung ...................8 1.2.2 Ergebnisse der Multiplikatorenbefragung .................23 1.2.3 Ergebnisse der Intermediärsbefragung .....................24 1.2.4 Ergebnisse der Wissenschaftlerbefragung ...............25 1.2.5 Zusammenfassung ....................................................30 Kapitel 2: Wirkungsstruktur ....................................................31 2.1 Thematische Eingrenzung .........................................31 2.2 Zur theoretischen Hinsicht: Zwei einleitende Vorbemerkungen ................................32 2.3. Die Wirkungsstruktur ......................................................33 2.3.1 Das innovative KMU........................................................34 2.3.2 Zwischenstand: Die Transfernähe innovativer KMU ...37 2.3.3 Der Umgang mit Forschungseinrichtungen ..............37 2.3.4 Wirtschaft und Wissenschaft: Zwei Parallelwelten ...40 2.4 Konkrete Bedingungen für erfolgreichen Wissenstransfer......................................................................42 2.4.1 Einordnung der üblichen Chiffren ..............................42 2.4.2 Der Escort Service für die Grauzone ... ...................44 2.4.3 …und das Problem der Königskinder ........................46 2.5 Literatur .....................................................................48 Kapitel 3: Rollenbilder Der systemische Ansatz .....................................................49 Soziales System .................................................................49 Der rollentheoretische Ansatz ............................................55 Grundannahmen über gelingende Kommunikationim Innovations-Transferraum ..............................................61 Literaturverzeichnis ............................................................63 Kapitel 4: Szenarien Transferszenarium: Ziele, Rollen, Interaktionen .................64 Akteure und Impulsgeber ...................................................65 Arbeitsbedingungen in Transferszenarien ..........................68 Motivation und Effekte .......................................................69 Unterschiedliche Situationen –unterschiedliche Szenarien .................................................70

Résumé : Les transferts d’électrons photo-induits et d’énergie jouent un rôle primordial dans un grand nombre de processus photochimiques et photobiologiques, comme la respiration ou la photosynthèse. Une très grande quantité de systèmes à liaisons covalentes ont été conçus pour copier ces processus de transferts. Cependant, les progrès sont, en grande partie, limités par les difficultés rencontrées dans la synthèse de nouveaux couples de types donneurs-accepteurs. Récemment, des espèces utilisant des liaisons non-covalentes, comme les liaisons hydrogènes, les interactions [pi]-[pi], les liaisons de coordination métal-ligands ou encore les interactions électrostatiques sont le centre d’un nouvel intérêt du fait qu’ils soient plus faciles à synthétiser et à gérer pour obtenir des comportements de transferts d’électrons ou d’énergie plus flexibles et sélectifs. C’est dans cette optique que le travail de cette thèse a été mené, i.e. de concevoir des composés auto-assemblés avec des porphyrines et un cluster de palladium pour l’étude des transferts d’électrons photo-induits et d’énergie. Cette thèse se divise en quatre parties principales. Dans la première section, le chapitre 3, deux colorants porphyriniques, soit le 5-(4-carboxylphényl)-10, 15, 20-tristolyl(porphyrinato)zinc(II) (MCP, avec Na+ comme contre-ion) et 5, 15-bis(4-carboxylphényl)-15, 20-bistolyl(porphyrinato)zinc(II) (DCP, avec Na+ comme contre-ion) ont été utilisés comme donneurs d’électrons, et le [Pd3(dppm)3(CO)]2+ ([Pd32+], dppm = (Ph2P)2CH2, PF6‾ est le contre-ion) a été choisi comme accepteur d’électrons. La structure de l’assemblage [Pd32+]•••porphyrine a été élucidée par l’optimisation des géométries à l’aide de calculs DFT. La spectroscopie d’absorption transitoire (TAS) montre la vitesse de transferts d’électrons la plus rapide (< 85 fs, temps inférieurs à la limite de détection) jamais enregistrée pour ce type de système (porphyrine-accepteur auto-assemblés). Généralement, ces processus sont de l’ordre de l’échelle de la ps-ns. Cette vitesse est comparable aux plus rapides transferts d’électrons rapportés dans le cas de systèmes covalents de type porphyrine-accepteur rapide (< 85 fs, temps inférieurs à la limite de détection). Ce transfert d’électrons ultra-rapide (ket > 1.2 × 1013 s-1) se produit à l’état énergétique S1 des colorants dans une structure liée directement par des interactions ioniques, ce qui indique qu’il n’est pas nécessaire d’avoir de forts liens ou une géométrie courbée entre le donneur et l’accepteur. Dans une deuxième section, au chapitre 4, nous avons étudié en profondeur l’effet de l’utilisation de porphyrines à systèmes π-étendus sur le comportement des transferts d’électrons. Le colorant 9, 18, 27, 36-tétrakis-meso-(4-carboxyphényl)tétrabenzoporphyrinatozinc(II) (TCPBP, avec Na+ comme contre-ion) a été sélectionné comme candidat, et le 5, 10, 15, 20-tétrakis-meso-(4-carboxyphényl)porphyrineatozinc(II) (TCPP, avec Na+ comme contre-ion) a aussi été utilisé à des fins de comparaisons. TCPBP et TCPP ont, tous deux, été utilisés comme donneurs d’électrons pour fabriquer des assemblages supramoléculaires avec le cluster [Pd32+] comme accepteur d’électrons. Les calculs DFT ont été réalisés pour expliquer les structures de ces assemblages. Dans les conditions expérimentales, ces assemblages sont composés principalement d’une porphyrine avec 4 équivalents de clusters. Ces systèmes ont aussi été investigués par des mesures de quenching (perte de luminescence), par électrochimie et par d’autres techniques. Les transferts d’électrons (< 85 fs; temps inférieurs à la limite de détection) étaient aussi observés, de façon similaire aux assemblages MCP•••[Pd32+] et [Pd32+]•••DCP•••[Pd32+]. Les résultats nous indiquent que la modification de la structure de la porphyrine vers la tétrabenzoporphyrine ne semble pas influencer le comportement des cinétiques de transferts d’électrons (aller ou retour). Dans la troisième section, le chapitre 5, nous avons synthétisé la porphyrine hautement [pi]-conjuguée: 9, 18, 27, 36-tétra-(4-carboxyphényléthynyl)tétrabenzoporphyrinatozinc(II) (TCPEBP, avec Na+ comme contre-ion) par des fonctionnalisations en positions meso- et β, β-, qui présente un déplacement vers le rouge de la bande de Soret et des bandes Q. TCPEBP était utilisé comme donneur d’électrons pour fabriquer des motifs supramoléculaires avec le [Pd32+] comme accepteur d’électrons. Des expériences en parallèle ont été menées en utilisant la 5, 10, 15, 20-tétra-(4-carboxyphényl)éthynylporphyrinatozinc(II) (TCPEP, avec Na+ comme contre-ion). Des calculs DFT et TDDFT ont été réalisés pour de nouveau déterminer de façon théorique les structures de ces systèmes. Les constantes d’association pour les assemblages TCPEBP•••[Pd32+]x sont les plus élevées parmi tous les assemblages entre des porphyrines et le cluster de palladium rencontrés dans la littérature. La TAS a montré, encore une fois, des processus de transferts d’électrons dans des échelles de l’ordre de 75-110 fs. Cependant, les transferts de retour d’électrons sont aussi très rapides (< 1 ps), ce qui est un obstacle potentiel pour des applications en cellules solaires à pigment photosensible (DSSCs). Dans la quatrième section, le chapitre 6, les transferts d’énergie triplets (TET) ont été étudiés pour les assemblages MCP•••[Pd32+] et [Pd32+]•••DCP•••[Pd32+]. Les analyses spectrales des états transitoires dans l’échelle de temps de la ns-[mu]s démontrent de façon évidente les TETs; ceux-ci présentent des transferts d’énergie lents et/ou des vitesses moyennes pour des transferts d’énergie T1-T1 (3dye*•••[Pd32+] → dye•••3[Pd32+]*) opérant à travers exclusivement le mécanisme de Förster avec des valeurs de kET autour de ~ 1 × 105 s-1 selon les mesures d’absorption transitoires à 298 K. Des forces motrices non-favorables rendent ces types de processus non-opérants ou très lents dans les états T1. L’état T1 de [Pd32+] (~8190 cm-1) a été qualitativement déterminé par DFT et par la mise en évidence de l’émission S0 ← Tn retardée à 680-700 nm provenant de l’annihilation T1-T1, ce qui fait que ce cluster peut potentiellement agir comme un donneur à partir de ses états Tn, et accepteur à partir de T1 à l’intérieur de ces assemblages. Des pertes d’intensités de types statiques pour la phosphorescence dans le proche-IR sont observées à 785 nm. Ce travail démontre une efficacité modérée des colorants à base de porphyrines pour être impliquée dans des TETs avec des fragments organométalliques, et ce, même attachées grâce à des interactions ioniques. En conclusion, les assemblages ioniques à base de porphyrines et de clusters de palladium présentent des propriétés de transferts d’électrons S1 ultra-rapides, et des transferts d’énergie T1 de vitesses modérées, ce qui est utile pour de possibles applications comme outils optoélectroniques. D’autres études, plus en profondeur, sont présentement en progrès. / Abstract : Photoinduced electron and energy transfers play the pivotal role in various photochemical and photobiological redox processes including photosynthesis and respiration. Abundant covalently bonded systems have been designed to mimic the natural electron and energy transfer processes. However, the progress is often interfered by the difficulties to synthesize novel and versatile covalent donor-acceptor pairs. Recently, entities utilizing non-covalent interactions including hydrogen-bonding, [pi]-[pi] stacking, metal-ligand coordination and electrostatic interactions are becoming a hot topic since they are easy to be fabricated and tuned for selective and flexible electron and energy transfer behaviors. In this respect, the work presented in this thesis designed self-assemblies with porphyrins and a palladium cluster for photoinduced electron and energy transfers. It includes four main sections. In the first section, Chapter 3, two porphyrinic dyes, 5-(4-carboxylphenyl)-10, 15, 20-tristolyl(porphyrinato)zinc(II) (MCP, as sodium salt) and 5, 15-bis(4-carboxylphenyl)-15, 20-bistolyl(porphyrinato)zinc(II) (DCP, as sodium salt), were used as electron donors, and [Pd3(dppm)3(CO)]2+ ([Pd32+], dppm = (Ph2P)2CH2, as PF6‾ salt) cluster was adopted as the electron acceptor. The structure of [Pd32+]•••porphyrin assemblies was elucidated by geometry optimization using Density Functional Theory (DFT) calculations. Transient absorption spectroscopy (TAS) indicated a record fast electron transfer rate (< 85 fs, the time resolution limit) among the porphyrin-acceptor self-assemblies. Typically, these occur in ps-ns time scale. This rate is also comparable to the fastest electron transfer rate reported for the covalently linked porphyrin-acceptor systems (~ 50 fs, the time resolution limit). The ultrafast photo-induced electron transfers (ket > 1.2 × 1013 s-1) occurring at the S1 levels of the dyes in the structurally well-defined “straight up” ionic assemblies indicate that it is not necessary to have a strong bond and bent geometry between the donor and acceptor. In the second section, Chapter 4, we further studied the effect of using π-extended porphyrins on the electron transfer behavior of these assemblies. 9, 18, 27, 36-Tetrakis-meso-(4-carboxyphenyl)tetrabenzoporphyrinatozinc(II) (TCPBP, as a sodium salt) was selected as the candidate, and the 5, 10, 15, 20-tetrakis-meso-(4-carboxyphenyl)porphyrinatozinc(II) (TCPP, as a sodium salt) dye was also studied for comparison purposes. TCPBP and TCPP were both utilized as electron donors to fabricate supramolecular assemblies with the [Pd32+] cluster as the electron acceptor. DFT calculations were used to explain the structure of these assemblies. Under the experimental conditions used, these assemblies mainly exist in the form of one porphyrin with four equivalent clusters. These systems were also investigated by quenching measurements, electrochemistry, and other techniques. Ultrafast electron transfers (< 85 fs; time resolution limit) were also observed, which is similar as those for MCP•••[Pd32+] and [Pd32+]•••DCP•••[Pd32+] assemblies. The results indicate the structural modification from porphyrin to tetrabenzoporphyrin does not seemingly influence the kinetic behavior of the forward and back electron transfers. In the third section, Chapter 5, we synthesized a highly [pi]-conjugated porphyrin, 9, 18, 27, 36-tetra-(4-carboxyphenylethynyl)tetrabenzoporphyrinatozinc(II) (TCPEBP, as a sodium salt) by meso- and β, β-bifunctionalization, which exhibits large red shift of the Soret and Q-bands. TCPEBP was utilized as electron donors to fabricate supramolecular motifs with [Pd32+] cluster as the electron acceptor. Parallel experiments were conducted using 5, 10, 15, 20-tetra-(4-carboxyphenyl)ethynylporphyrinatozinc(II) (TCPEP, as a sodium salt). DFT and TDDFT calculations were applied to elucidate the structure of these assemblies. Binding constants for TCPEBP•••[Pd32+]x is the largest one among all the assemblies with porphyrin and palladium cluster. TAS showed again the ultrafast electron transfer process within the 75-110 fs time frame. However, the back electron transfers are also very fast (< 1 ps), which may be a potential obstacle for future applications in dye-sensitized solar cells (DSSCs). In the fourth section, Chapter 6, triplet energy transfers (TET) of the assemblies MCP•••[Pd32+] and [Pd32+]•••DCP•••[Pd32+] were studied. The transient spectral analysis in the ns-[mu]s time scale clearly demonstrates evidence for TET, which shows a slow to medium T1-T1 energy transfer (3dye*•••[Pd32+] → dye•••3[Pd32+]*) operating through a Förster mechanism exclusively with kET values of ~ 1 × 105 s-1 based on transient absorption measurements at 298 K. Unfavourable reductive and oxidative driving forces make this type of process inoperative or very slow in the T1 states. The T1 state of [Pd32+] (~8190 cm-1) has been quantitatively determined by DFT computations and by evidence for a delayed S0 ← Tn emission at 680-700 nm arising from T1-T1 annihilation, which makes this cluster potentially acting as the energy donor from its Tn state, and T1 acceptor within the assemblies. The static quenching of their near-IR phosphorescence at 785 nm was observed. This work demonstrated a moderate efficiency of the porphyrin dye to be involved in TET with an organometallic fragment, even when attached through ionic interactions. Conclusively, ionic assemblies with porphyrins and palladium clusters exhibit ultrafast S1 electron transfer and moderate T1 energy transfer properties, which is useful for possible application as optoelectronic devices. Further research in more depth is in progress.

Tyrosine tRNA was isolated from bovine liver and its nucleotide sequence was determined using in vitro 32p_ labeling techniques. Several important structural features of the tRNA are: the presence of gal-Q in the first position of the anticodon, acp3U at position 20, and a pair of adjacent N,N-dimethylguanosines (residues 26 and 27). A human DNA fragment harbored in a lambda phage clone was isolated, and restriction enzyme analysis revealed the presence of three tRNA genes in a 6.0-kb BamHI subfragment. Portions of the 6.0-kb DNA fragment containing the tRNA genes were sequenced by the method of Maxam and Gilbert and analyzed for transcriptional activity in vitro using homologous cytoplasmic extracts. A threonine tRNAUGU gene exhibited high transcriptional activity dependent on its 5'- flanking sequence. The enhanced transcription is not completely inhibited by alpha-amanitin. The value of studying tRNA structure in concert with the cognate tRNA. genes is discussed.