From Time to Time: A Constructivist Approach to Sociality in Learning

[EN] Under the current financial pressures, tertiary education increasingly looks towards corporate sector to import its model of management and efficiency. While benefits of this model can be seen in practice, in regard to staff and facilities management and financial viability, its impact on teaching and learning caused a disruption to the very core of tertiary education, eroding sociality in learning and opportunity for sharing knowledge and values. Capacity to work in teams and ability to critically solve problems by collaborating and sharing insights and informations, are skills students are expected to gain during their studies. The development of these skills to their fullest using Design Thinking approach, however, is currently not widely supported, albeit desirable,[1] in the present education context which is addressing the efficiency of time management by reducing contact time, increasing student/staff ratio and shifting towards integrated and mass education modes of delivery. While this presentation is not disputing the existing model, it responds to its current challenges proposing a stronger integration of different factors contributing to learning.Tthe aim is to present a collaborative working model as a way of bridging ‘the missing link between theoretical findings [on holistic and interdisciplinary learning] and demands by pedagogy science’[2]. Such a model is envisioned to encourage sociality in learning and strategize space/time/experience management, ultimately enhancing knowledge and value sharing. [1] Ability to solve ‘wicked problems’ as supported by Design Thinks is becoming more attractive to the tertiary sector as it promotes ‘holistic modes of constructivist learning in projects’ (Sheer et al 17 (3), 8). [2] Sheer et al 17 (3), 8http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Mancini, F.; Glusac, T. (2018). From Time to Time: A Constructivist Approach to Sociality in Learning. Editorial Universitat Politècnica de València. 1567-1576. https://doi.org/10.4995/HEAD18.2018.8255OCS1567157

Light-triggered Proton And Electron Transfer In Flavin Cofactors

The pH dependent behavior of two flavin cofactors, flavin-adenine dinucleotide (FAD) and flavin mononucleotide (FMN), has been characterized using femtosecond transient absorption spectroscopy for the first time. The flavin excited state was characterized in three states of protonation (Fl(-), Fl, and FlH(+)). We found that Fl and Fl(-) exhibit the same excited state absorption but that the lifetime of Fl(-) is much shorter than that of Fl. The transient absorption spectrum of FlH(+) is significantly different from Fl and Fl(-), suggesting that the electronic properties of the flavin chromophore become appreciably modified by protonation. We further studied the excited state protonation of the flavin and found that the protonation sites of the flavin in the ground and excited state are not equivalent. In the case of FAD, its excited state dynamics are controlled by the two conformations it adopts. At low and high pH, FAD adopts an open conformation and behaves, the same as FMN. In a neutral pH range, FAD undergoes a fast excited state deactivation due to the stacked conformer. The transition from stacked to open conformer occurs at pH similar to 3 (because of adenine protonation) and pH similar to 10 (because of flavin deprotonation)

The Role Of Adenine In Fast Excited-state Deactivation Of Fad: A Femtosecond Mid-ir Transient Absorption Study

We present a study of excited-state dynamics of two flavin cofactors: flavin-adenine dinucleotide (FAD) and flavin-mononucleotide (FMN). We used femtosecond mid-R transient absorption spectroscopy to study the effect of FAD conformation oil its excited-state behavior. The conformation of FAD was modulated by changing the solvent polarity: in D(2)O, FAD is present predominantly in the stacked conformation, in which flavin and adenine moieties are in close proximity to each other, whereas the increased amount of DMSO led to an increased amount of the open conformer. FMN served as a model system which lacks adenine. We found that the stacked conformer undergoes ail intramolecular photoinduced electron transfer from adenine to flavin with the forward electron transfer rate of k(f) = 1.9 . 10(11) s(-1) and the geminate recombination rate of k(b) = 1.1 . 10(11) s(-1). In the case of the open conformer, no intramolecular electron transfer was observed

Role Of Adenine In Thymine-dimer Repair By Reduced Flavin-adenine Dinucleotide

We present a study of excited-state behavior of reduced flavin cofactors using femtosecond optical transient absorption spectroscopy. The reduced flavin cofactors studied were in two protonation states: flavin-adenine dinucleotide (FADH(2) and FADH(-)) and flavin-mononucleotide (FMNH2 and FMNH-). We find that FMNH- exhibits multiexponential decay dynamics due to the presence of two bent conformers of the isoalloxazine ring. FMNH2 exhibits an additional fast deactivation component that is assigned to an iminol tautomer. Reduced flavin cofactors also exhibit a long-lived component that is attributed to the semiquinone and the hydrated electron that are produced in photoinduced electron transfer to the solvent. The presence of adenine in FADH(2) and FADH- further changes the excited-state dynamics due to intrarnolecular electron transfer from the isoalloxazine to the adenine moiety of cofactors. This electron transfer is more pronounced in FADH, due to pi-stacking interactions between two moieties. We further studied cyclobutane thymine dimer (TT-dimer) repair via FADH- and FMNH- and found that the repair is much more efficient in the case of FADH-. These results suggest that the adenine moiety plays a significant role in the TT-dimer repair dynamics. Two possible explanations for the adenine mediation are presented: (1) a two-step electron transfer process, with the initial electron transfer occurring from flavin to adenine moiety of FADH-, followed by a second electron transfer from adenine to TT-dimer (ii) the preconcentration of TT-dimer molecules around the flavin cofactor due to the hydrophobic nature of the adenine moiety

Architecture and belonging: Migration, re-territorialisation and self-identity

This thesis investigates connections between architecture, culture, memory and habitus and the role architecture and the built environment play in promoting self-identity and belonging. It explores these issues through the complexity of migration resettlement and its impact on built forms, demonstrating the rich qualities of life and personal being that individuals bring to architecture and the failure of conventional architectural discourse and practice to acknowledge or respond to the necessity of informing identity and belonging

Photoinduced Charge Separation In Platinum Acetylide Oligomers

The series of three donor-spacer-acceptor complexes, DPAF-Ptn-NDI, has been synthesized and characterized using time-resolved absorption spectroscopy In these complexes, the donor is a (diphenylamino)-2,7-fluorenylene (DPAF) unit, the acceptor is a naphthalene diimide (NDI), and the spacers are a series of platinum acetylides of varying lengths, [-Pt(PBu(3))(2)C C-Ph-C C-](n) (where Bu = n-butyl Ph = 1,4-phenylene and n = 1 2, and 3) Electrochemistry indicates that the DPAF-Ptn-NDI system has a charge transfer state at ca 1 5 eV above the ground state that is based on one electron transfer from the DPAF donor to the NDI acceptor Transient absorption spectroscopy on time scales ranging from 0 2 ps to 1 mu s reveals that excitation of all of the complexes leads to production of the charge transfer state with nearly unit quantum efficiency The rates for charge separation and charge recombination are not strongly dependent upon the length of the platinum acetylide spacer, suggesting that the spacer is actively involved in the electron (hole) transport processes Analysis of the experimental results leads to a model in which charge separation and charge recombination occur by hole-hopping via states localized on the [-Pt(PBu(3))(2)C C-Ph-C C-](n) bridge

Electronic Properties Of 4-substituted Naphthalimides

This paper describes a study of excited-state properties of naphthalmide (NI) and four 4-substituted derivatives: 4-chloronaphthalimide (Cl-NI), 4-methylthionaphthalmide (MeS-NI), 4-nitronaphthalimide (O(2)N-NI), and 4-(N,N-dimethylaminonaphthalimide (Me(2)N-NI). Steady-state absorption and fluorescence spectra were collected in solvents of varying polarity to determine the excited-state character of NI derivatives. Furthermore. the excited-state dynamics were studied Using femtosecond transient absorption spectroscopy. The experimental findings were compared to calculated data obtained using time-dependent density functional (TD-DFT) methods. We found that light absorption by all NI derivatives leads to the production of the second excited state (S(2)), which was found to have a n,pi* character. Within similar to 40 ps, the S(2) state undergoes internal conversion to produce the S(1) state. The S(1) state is relatively long-lived (similar to 4 ns) and has charge-transfer character in NI derivatives with electron-withdrawing and electron-donating groups (MeS-NI, O(2)N-Ni, and Me(2)N-NI). In the case of NI and Cl-NI, the S(1) state has a pi,pi* character and undergoes intersystem crossing to produce the T(1) state within 400 ps

Photoinduced Electron Transfer In Naphthalimide-pyridine Systems: Effect Of Proton Transfer On Charge Recombination Efficiencies

We studied the effect of proton-coupled electron transfer on lifetimes of the charge-separated radicals produced upon light irradiation of the thiomethyl-naphthalimide donor SMe-NI-H in the presence of nitro-cyano-pyridine acceptor (NO(2)-CN-PYR). The dynamics of electron and proton transfer were studied using femtosecond pump-probe spectroscopy in the UV/vis range. We find that the photoinduced electron transfer between excited SMe-NI-H and NO(2)-CN-PYR occurs with a rate of 1.1 x 10(9) s(-1) to produce radical ions SMe-NI-H(center dot+) and NO(2)-CN-PYR(center dot-). These initially produced radical ions in a solvent cage do not undergo a proton transfer, possibly due to unfavorable geometry between N-H proton of the naphthalimide and aromatic N-atom of the pyridine. Some of the radical ions in the solvent cage recombine with a rate of 2.3 x 10(10) s(-1), while some escape the solvent cage and recombine at a lower rate (k = 4.27 x 10(8) s(-1)). The radical ions that escape the solvent cage undergo proton transfer to produce neutral radicals SMe-NI(center dot) and NO(2)-CN-PYR-H(center dot). Because neutral radicals are not attracted to each other by electrostatic interactions, their recombination is slower that the recombination of the radical ions formed in model compounds that can undergo only electron transfer (SMe-NI-Me and NO(2)-CN-PYR, k = 1.2 x 10(9) s(-1)). The results of our study demonstrate that proton-coupled electron transfer can be used as an efficient method to achieve long-lived charge separation in light-driven processes

Excited-State Hydroxide Ion Release From a Series of Acridinol Photobases

The excited-state heterolysis of acridinol-based derivatives leads to the release of the OH- ion and the formation of the corresponding acridinium cations. To evaluate the parameters that control the reaction barriers, the kinetics of excited-state OH- release from a series of acridinol photobases were studied using transient absorption spectroscopy. The rate constants were obtained in three solvents (methanol, butanol, and isobutanol), and the data were modeled using Marcus theory. The intrinsic reorganization energies obtained from these fits were found to correlate well with the solvent reorganization energies calculated using dielectric continuum model, suggesting that the excited-state OH- release occurs along the solvent reaction coordinate. Furthermore, the ability of acridinol photobases to photoinitiate chemical reactions was demonstrated using the Michael reaction between dimethylmalonate and nitrostyrene

Pinpointing The Extent Of Electronic Delocalization In The Re(i)-to-tetrazine Charge-separated Excited State Using Time-resolved Infrared Spectroscopy

Femtosecond mid-IR transient absorption spectroscopy (TRIR) and time-dependent density functional theory (TD-DFT) calculations on Re(CO)(3)Cl(Me(2)BPTZ) [Me(2)BPTZ = 3,6-bis(5-methyl-2-pyridine)-1,2,4,5-tetrazine] are used to demonstrate that the lowest excited state of the complex is a triplet metal-to-ligand charge-transfer ((3)MLCT) state with a lifetime of 225 ps. The short excited-state lifetime is explained by the energy-gap taw. Vibrational cooling of the (3)MLCT state shows up as early-time dynamics (3.6 ps). The structural changes in the excited state are deduced from the frequency shifts in the TRIR vibrational bands. The vibrational frequencies of the CO groups increase upon excitation as a result of decreased back-bonding between the CO ligands and the oxidized Re center in the (3)MLCT state. The vibrational frequencies of the central tetrazine ring of Me(2)BPTZ decrease because of the decrease in the bond order upon reduction of the Me(2)BPTZ ligand in the (3)MLCT state. Interestingly, the TRIR signals from the pyridine moieties of Me2BPTZ were not detected. These results can be explained by localization of the electronic charge on the central tetrazine ring in the (3)MLCT state of Re(CO)(3)Cl(Me(2)BPTZ), as supported by TD-DFT calculations