24 research outputs found
The 4Cs of adaptation tracking: consistency, comparability, comprehensiveness, coherency
Adaptation tracking seeks to characterize, monitor, and compare general trends in climate change adaptation over time and across nations. Recognized as essential for evaluating adaptation progress, there have been few attempts to develop systematic approaches for tracking adaptation. This is reflected in polarized opinions, contradictory findings, and lack of understanding on the state of adaptation globally. In this paper, we outline key methodological considerations necessary for adaptation tracking research to produce systematic, rigorous, comparable, and usable insights that can capture the current state of adaptation globally, provide the basis for characterizing and evaluating adaptations taking place, facilitate examination of what conditions explain differences in adaptation action across jurisdictions, and can underpin the monitoring of change in adaptation over time. Specifically, we argue that approaches to adaptation tracking need to (i) utilize a consistent and operational conceptualization of adaptation, (ii) focus on comparable units of analysis, (iii) use and develop comprehensive datasets on adaptation action, and (iv) be coherent with our understanding of what constitutes real adaptation. Collectively, these form the 4Cs of adaptation tracking (consistency, comparability, comprehensiveness, and coherency)
Cellulose Derivatives Membranes as Supports for Immobilisation of Enzymes
Cellulosic derivatives (cellulose acetate, cellulose propionate and cellulose acetate-butyrate) as membranes, were prepared in different ways. These were then characterised by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and contact angle evaluation. Subsequently, catalase (H2O2:H2O2 oxireductase; EC 1.11.1.6), alcohol oxidase (Alcohol:oxygen oxireductase; EC 1.1.3.13) and glucose oxidase (Ă-D- Glucose:oxygen 1-oxireductase; EC 1.1.3.4) were covalently linked to these membranes. The catalytic activity and stability of these enzymes, when immobilised, were examined. The results obtained showed that the immobilisation efficiency and the stability of the coupled enzymes could be correlated with the studied properties of the supports. The cellulose acetate membrane which was prepared by evaporation gave the more active conjugate support-enzyme. Membranes prepared by the immersion technique were more crystalline and therefore less suitable for enzyme immobilisation. The highly hydrophobic membranes, obtained from the propionate and the butyrate esters of cellulose reduced the activities but gave better storage stability
Molecular Dynamics of Cyclodextrins in Water Solutions from NMR Deuterium Relaxation : Implications for Cyclodextrin Aggregation
The aggregation of the most common natural cyclodextrins (α-, ÎČ-, and Îł-) in aqueous solutions is addressed by studying the CD-CD interactions using deuterium relaxation rates for deuterium labeled CDs. Relaxation times (T1) and their corresponding relaxation rates (R1 = 1/T1) provide information about the rotational correlation times of CDs and serve as a proxy for solute-solute interactions. Measured T1's for α-, ÎČ-, and Îł-CD at the lowest CD concentrations were in agreement with predictions of a hydrodynamic model for toroids, in particular with regard to the dependence of T1 on CD size. On the other hand, the dependence of T1's with respect to the increase in CD concentration could not be explained by hydrodynamic or direct interaction between CD molecules, and it is suggested that there is an equilibrium between monomeric and dimeric CD to account for the observed concentration dependence. No evidence in favor of large aggregates of CDs involving a non-negligible fraction was found for the investigated CDs
Pyrrolidine-based amino alcohols: novel ligands for the enantioselective alkylation of benzaldehyde
A series of easily obtained pyrrolidine-based [beta]-amino alcohols derived from tartaric acid and primary amines was synthesized and used as chiral ligands in the enantioselective alkylation of benzaldehyde. Using diethylzinc, 1-phenyl-1-propanol was obtained with enantiomeric excesses of up to 80% when (3S,4S)-N-(1-naphthylmethyl)-3,4-dihydroxypyrrolidine was used. The nature of the N-substituent on the ligand, as well as the reaction temperature proved to significantly influence reaction product distribution as well as the enantiomeric excess of the chiral alcohol.http://www.sciencedirect.com/science/article/B6TGM-4790515-2/1/7b585f37987962e55a30bf6583ce3e0
Chiral Thiazolidine based Organocatalysts: Synthesis and Application in Asymmetric Aldol Reactions
Several novel chiral organocatalysts derived from thiazolidines containing amide and thioureia functionalities were synthesized in good yields. These organocatalysts were tested in the asymmetric aldol reaction of acetone with p-nitrobenzaldehyde. Reaction parameters such as reaction time, catalyst loading and solvent were optimized. Products with conversions up to 84% and enantiomeric ratios (er) up to 84.5:15.5 (R:S) were obtained. The effect of several chiral and non-chiral additives on the reactivity and selectivity of the reaction was also evaluated. The reaction was extended to other aromatic aldehydes with the best organocatalyst and when p-bromobenzaldehyde was used, an er of 94.5:5.5 (R:S) was obtained
Organophotocatalytic Aerobic Oxygenation of Phenols in a VisibleâLight ContinuousâFlow Photoreactor
Incorporation of a Cationic Conjugated Polyelectrolyte CPE within an Aqueous Poly(vinyl alcohol) Sol
NoWe report on a multiscale polymer-within-polymer structure of the cationic conjugated polyelectrolyte poly{[9,9-bis(6âČ-N,N,N-trimethylammonium)hexyl]fluoreneâphenylene} (HTMA-PFP) in aqueous poly(vinyl alcohol) (PVA) sol. Molecular dynamics simulations and small-angle neutron scattering (SANS) data show that HTMA-PFP forms aggregates in water but becomes entangled by PVA (with a 1:1 molar ratio of HTMA-PFP to PVA) and eventually immersed in PVA clusters (with the ratio 1:4). This is attributed to the hydrophobicâhydrophilic balance. Contrast variation data with regular and deuterated PVA support a rigid body model, where HTMA-PFP is confined as locally isolated, but closely located, chains within PVA clusters, which alter correlation distances within the system. These results are supported by enhanced photoluminescence (PL) and ionic conductivity which, together with a red-shift in UV/vis absorption spectra, indicate the breakup of HTMA-PFP aggregates upon PVA addition
Transport and photophysical studies on porphyrin-containing sulfonated poly(etheretherketone) composite membranes
The development of efficient and reliable membranes for redox flow batteries (RFBs) with high ionic conductivity
and selectivity is challenging. Aiming the development of better membranes, we have synthesized
porphyrin-containing sulfonated poly(etheretherketone) (SPEEK). In particular, the effect of water soluble
5,10,15,20-tetrakis(N-methyl-4-pyridinyl)porphyrin iodide (TMePyPI4) and its Cu(II) complex, 5,10,15,20-tetrakis(
N-methyl-4-pyridinyl)porphyrinate copper(II) iodide, (CuTMePyPI4), at 0.1â0.3 wt%, have been assessed.
Photophysical studies have shown that porphyrins are aggregated in the J-type. The obtained composite membranes
show high macroscopic homogeneity and lower ability to sorb water when compared with pristine SPEEK
membranes but comparable protonic conductivity. The hydronium diffusion and permeability coefficients suggest
that at low porphyrin concentrations an enhancement of proton channels occurs, whilst at high concentration
that effect decreases due to the formation of porphyrin aggregates. A similar effect occurs in the
permeation of vanadium ions through composite membranes with a remarkable lower permeability and diffusion
coefficients when compared with those obtained for Nafion 115 membranes. This along with the improved
thermal stability of porphyrin-containing SPEEK composite membranes indicate that these advanced materials
can be used for improving the performance of RFBs.This work was supported by Projects âHylightâ (no. 031625/02/ SAICT/2017, PTDC/QUI-QFI/31625/2017, which is funded by the Portuguese Science Foundation and Compete Centro 2020 (Portugal), Project Suprasol (LISBOA-01-0145-FEDER-028365 -PTDC/QUI-QOR/ 28365/2017), funded by Fundo Europeu de Desenvolvimento Regional (FEDER), through Programa Operacional Regional Lisboa (LISBOA2020, Portugal), and project âSunStorage - Harvesting and storage of solar energyâ for financial support, reference POCI-01-0145-FEDER-016387, funded by FEDER, through COMPETE 2020 â Operational Programme for Competitiveness and Internationalization (OPCI), and by national funds, through FundaçËao para a CiËencia e a Tecnologia (FCT) and Portuguese Agency for Scientific Research (Portugal). We acknowledge funding by Fundo Europeu de Desenvolvimento Regional (FEDER) through Programa Operacional Factores de Competitividade (COMPETE). L.D. Dias thanks FAPESP (Brazil) for the Post-doc grant 2019/13569-8, J. Azevedo would like to acknowledge the Portuguese Foundation for Science and Technology (FCT, Portugal) for funding (CEECIND/03937/2017) and P. Dias is grateful to FCT her individual contract (CEECIND/02862/2018). C. Gomes thanks FCT (Portugal) for PhD grant FCT- CATSUS PhD Program (PD/BD/135531/2018. The Coimbra Chemistry Centre is supported by the FCT, through Projects UIDB/00313/2020 and UIDP/00313/2020 and CQE is supported by FCT through project UID/QUI/00100/2019. LEPABE has also received funding from: i) Project PTDC/EQU-EQU/30760/2017 â HopeH2, Efficient, stable and scalable PEC-PV device for solar hydrogen generation - POCI-01-0145-FEDER-030760; and (ii) Project PTDC/EQU-EQU/ 30510/2017 â SunFlow, Solar energy storage into redox flow batteries - POCI-01-0145-FEDER-030510, both funded by the European Regional Development Fund (ERDF), through COMPETE2020 - Operational Programme for Competitiveness and Internationalisation (OPCI, Portugal) and by national funds, through FCT