Search results for "testing."
showing 10 items of 1654 documents
Bioresponsive poly(amidoamine)s designed for intracellular protein delivery.
2013
Poly(amidoamine)s with bioreducible disulfide linkages in the main chain (SS-PAAs) and pH-responsive, negatively charged citraconate groups in the sidechain have been designed for effective intracellular delivery and release of proteins with a net positive charge at neutral pH. Using lysozyme as a cationic model protein these water soluble polymers efficiently self-assemble into nanocomplexes by charge attraction. At pH 5 (the endosomal pH) the amide linkages connecting the citraconate groups in the sidechains of the SS-PAAs are hydrolyzed by intramolecular catalysis, resulting in expulsion of the negative citraconate groups and formation of protonated amine groups, resulting in charge reve…
Barriers to rotation in ortho-substituted tertiary aromatic amides: Effect of chloro-substitution on resonance and distortion
2018
Planarity of the amide bond represents one of the most widely recognized properties of amides. Herein, we report a combined structural and computational study on the effect of ortho-substitution on resonance and barriers to rotation in tertiary aromatic amides. We demonstrate that ortho-chloro substitution in a class of benzamides that are important from the reactivity and medicinal chemistry perspective results in increased barriers to rotation around both the N-C(O) and C-C(O) axes. The effect of steric hindrance on structures, resonance energies, barriers to rotation, and proton affinities is discussed. The present study strongly supports the use of ortho-substitution in common benzamide…
Synthesis and structural characterisation of bulky heptaaromatic (hetero)aryl o-substituted s-aryltetrazines
2020
An expedient two-step synthesis produces in good yield polyaromatic heptacyclic (hetero)arylated o-substituted s-aryltetrazines (s-Tz) directly from diphenyl s-tetrazine. This methodology overcomes the steric limitations of classical Pinner-like syntheses encountered for o-functionalized s-Tz. A single step palladium-catalyzed N-directed C–H bond tetrahalogenation is followed by a Pd-catalyzed Suzuki (hetero)arylation that is achieved simultaneously on four sites. The single crystal X-ray diffraction structure of the resulting typical polyaromatic heptacyclic aromatic compound 3,6-bis(2,6-diphenyl)-1,2,4,5-tetrazine (3) is analyzed, together with R-functionalized peripheral phenyl derivativ…
Benzoannulated quinone-type electron acceptors: evolution of the molecular and electronic structures upon reduction
1998
Abstract The molecular and electronic structures of DCNQI and its π-extended derivatives benzo-DCNQI and DCAQI have been investigated using ab initio 6-31G ∗ calculations. The steric hindrance introduced by lateral benzoannulation determines the loss of planarity of the DCNQI moiety for DCAQI. The most stable conformation of DCAQI corresponds to a butterfly-type structure, in which the DCNQI ring adopts a boat conformation and the lateral benzene rings remain planar. This structure lies 2.75 kcal mol −1 below the fully planar conformation. MP2/6-31G ∗ calculations including full geometry optimization confirm the greater stability of the butterfly structure. The geometries of the anions and …
Prediction of Airport Pavement Moduli by Machine Learning Methodology Using Non-destructive Field Testing Data Augmentation
2022
For the purpose of the Airport Pavement Management System (APMS), in order to optimize the maintenance strategies, it is fundamental monitoring the pavement conditions’ deterioration with time. In this way, the most damaged areas can be detected and intervention can be prioritized. The conventional approach consists in performing non-destructive tests by means of a Heavy Weight Deflectometer (HWD). This equipment allows the measurement of the pavement deflections induced by a defined impact load. This is a quite expensive and time-consuming procedure, therefore, the points to be investigated are usually limited to the center points of a very large mesh grid. Starting from the measured defle…
Balanced difficulty task finder: an adaptive recommendation method for learning tasks based on the concept of state of flow
2020
An adaptive task difficulty assignment method which we reckon as balanced difficulty task finder (BDTF) is proposed in this paper. The aim is to recommend tasks to a learner using a trade-off between skills of the learner and difficulty of the tasks such that the learner experiences a state of flow during the learning. Flow is a mental state that psychologists refer to when someone is completely immersed in an activity. Flow state is a multidisciplinary field of research and has been studied not only in psychology, but also neuroscience, education, sport, and games. The idea behind this paper is to try to achieve a flow state in a similar way as Elo’s chess skill rating (Glickman in Am Ches…
On the improvement of monumental structure safety: a case study
2006
The present paper deals with the problem of the preservation of the monumental patrimony and discusses a practical application. The analysis methodology based on modern dynamic identification techniques was used for a monumental church in the historic area of Catania (Italy). The dynamic response of the church was measured in terms of accelerations, by means of vibration tests in situ. The numerical analyses highlighted the vulnerability of the drum dome system. Hence interest focused on this part of the building. A reduced scale model of the above system was built to be subjected to dynamic tests on a shaking table at the ENEA laboratory at Casaccia (Rome). Different kinds of reversible de…
The Role of Anisotropy on the Volumetric Behaviour of Opalinus Clay upon Suction Change
2017
An experimental investigation to analyse the anisotropic volumetric response of shaly and sandy facies of Opalinus Clay upon suction variations is presented. Obtained results demonstrate the different behaviour of the tested facies to a wetting-drying cycle. The shaly facies exhibits higher water retention capacity and stronger volumetric response than the sandy facies. Anisotropic response is experienced by both facies with the strain perpendicular to bedding higher than in the parallel direction. The sandy facies exhibits a more pronounced anisotropic behaviour in particular during the drying phase. A detailed analysis of the response in the two directions with respect to the bedding orie…
Dark Spots in Trade Theory: Early Testing Attempts
2020
The beginnings of the economic theory correspond to philosophers’ attempts to explain why and how do countries trade with each other. Yet even more puzzling was the question how should countries trade? It is no surprise that despite the formidable developments of the theory in the last 200 years plus, there still are dark spots in the economics of trade. Globalization has rendered the issue even murkier. Beside the fact that international trade cannot be insulated from other economic domains, which makes it inadequate for experiments, but even testing itself is cumbersome. Only, evidence on such a complex field as international trade is by no means easy to come by.
Isolated in-vitro perfusion of pig hearts obtained from the abattoir: an alternative to animal experiments?
1994
Isolated pig hearts (German farm pigs) were characterized after global in-vivo ischaemia as a potential alternative to in-vivo animal studies. Hearts were harvested from adult farm swine at the abattoir 10.3 +/- 2.1 min after incision of the carotid artery. They were immediately perfused and thereafter stored in ice-cold cardioplegic (St Thomas's) solution. After 38 +/- 3 min, retrograde perfusion was started with oxygenated pig blood (37 degrees C; 5000 U Heparin.l-1; pH 7.38 +/- 0.1; 11 mmol glucose.l-1) at a flow rate of 85 ml.min-1 100 g-1 wet weight (gww-1) for 30 min (n = 10). Additionally, shortly after obtaining the hearts, ATP and CP content were measured by enzymatic tests in 10 p…