Search

Item does not contain fulltext

This book was presented to Professor Dr Rainer Prokisch on his retirement from the chair of International Tax Law at Maastricht University. He arrived at Maastricht in 2000 and was twice the Head of the Department of Tax Law for over ten years.

Contains fulltext : 242683.pdf (Publisher’s version ) (Closed access)

Contains fulltext : 242683.pdf (Publisher’s version ) (Closed access)

Contains fulltext : 242683.pdf (Publisher’s version ) (Closed access)

Regression is one of the most commonly used statistical techniques. However, testing regression systems is a great challenge because of the absence of test oracle in general. In this paper, we show that Metamorphic Testing is an effective approach to test multiple linear regression systems. In doing so, we identify intrinsic mathematical properties of linear regression, and then propose 11 Metamorphic Relations to be used for testing. Their effectiveness is examined using mutation analysis with a range of different regression programs. We further look at how the testing could be adopted in a more effective way. Our work is applicable to examine the reliability of predictive systems based on regression that has been widely used in economics, engineering and science, as well as of the regression calculation manipulated by statistical users., Comment: 24 pages, 5 figures, 7 tables. The Journal of Systems and Software (2021)

Ten years ago, European health care professional societies, health associations and members of the European Parliament convened in Brussels to discuss the necessary and urgent actions needed to improve access, initiation and follow up nutritional care for European citizens. As a response to this, in 2014 the Optimal Nutritional Care for All (ONCA) campaign was launched under the leadership of the European Nutritional for Health Alliance and its members. As of today this campaign has been rolled out in 18 European countries, whereby national multi-disciplinary platforms including patient groups work together to implement national nutritional care programs and develop good practices in care, research, education in order to increase awareness on malnutrition and improve nutritional care. This article describes the making of and evolution of the ONCA campaign, the outcomes and impact created, as well as opportunities to accelerate implementation of personalized nutritional care for all European citizens.

The Sydney Heart Bank (SHB) is one of the largest human heart tissue banks in existence. Its mission is to provide high-quality human heart tissue for research into the molecular basis of human heart failure by working collaboratively with experts in this field. We argue that, by comparing tissues from failing human hearts with age-matched non-failing healthy donor hearts, the results will be more relevant than research using animal models, particularly if their physiology is very different from humans. Tissue from heart surgery must generally be used soon after collection or it significantly deteriorates. Freezing is an option but it raises concerns that freezing causes substantial damage at the cellular and molecular level. The SHB contains failing samples from heart transplant patients and others who provided informed consent for the use of their tissue for research. All samples are cryopreserved in liquid nitrogen within 40 min of their removal from the patient, and in less than 5–10 min in the case of coronary arteries and left ventricle samples. To date, the SHB has collected tissue from about 450 failing hearts (>15,000 samples) from patients with a wide range of etiologies as well as increasing numbers of cardiomyectomy samples from patients with hypertrophic cardiomyopathy. The Bank also has hearts from over 120 healthy organ donors whose hearts, for a variety of reasons (mainly tissue-type incompatibility with waiting heart transplant recipients), could not be used for transplantation. Donor hearts were collected by the St Vincent’s Hospital Heart and Lung transplantation team from local hospitals or within a 4-h jet flight from Sydney. They were flushed with chilled cardioplegic solution and transported to Sydney where they were quickly cryopreserved in small samples. Failing and/or donor samples have been used by more than 60 research teams around the world, and have resulted in more than 100 research papers. The tissues most commonly requested are fr, Correction in: Biophysical Reviews, vol. 10, issue. 3, page. 941. DOI: 10.1007/s12551-018-0397-4QC 20220322

Reactions of TpRuH(CH3CN)(PPh3) with free silanes HSiR3 (R-3 = Et-3, (EtO)(3), Ph-3, HEt2, HPh2, and H2Ph) in THF yield the complexes TpRu(PPh3)(H)(eta(2)-HSiR3), the formulation of which is inferred from NMR spectroscopic data. The chemical equivalence of the two hydrogen atoms of TpRu(PPh3)(H)(eta(2)-HSiR3) down to -100 degrees C is attributed to rapid fluxionality between the two, i.e., TpRu(PPh3)(H-a)(eta(2)-HbSiR3) reversible arrow TpRu(PPh3)(H-b)(eta(2)-HaSiR3). Molecular orbital calculations at the B3LYP level have been performed to investigate the stereochemistry and the interconversion processes of various structural isomers for TpRu(PPh3)(H)(eta(2)-HSiR3). The results further support the existence of a eta(2)-silane formulation for these complexes. Two stable structures, with a nonclassical eta(2)-silane ligand, have been found. These two structural isomers are found to be in equilibrium with a low reaction barrier (7.5 kcal/mol). The interconversion between the enantiomeric pair of the most stable structure has almost no reaction barrier (0.5 kcal/mol). Together with the experimental findings, a mechanistic cycle is proposed. The complexes TpRu(PPh3)(H)(eta(2)-HSiR3) react reversibly with pressurized H-2, CH3CN, and PPh3 to give TpRuH(Hz)(PPh3), TpRuH(CH3CN)(PPh3), and TpRuH(PPh3)(2), respectively.

The complex RuH2(PCy3)(2)(trans-kappa-eta(2)-H ... SiMe2-o-C6H4-SiMe2... H) exhibits a number of intriguing structural features, in particular the apparent trans configuration of the two H ... Si units, the nearly collinear axial trans-H-Ru-H bonds, and the adoption of a near-C-2v symmetry. Theoretical studies indicate that, in the experimental structure, the drastic distortion of the two H ... Si units avoids the competition, for sigma{*}back-donation. while strengthening both the axial Ru-H and the Ru-Si bonds through a favorable orbital interaction with the metal d-orbitals. Such distortion is enhanced by the presence of chelation. which forces a small Si-Ru-Si angle. The H ... Si interaction distance is 1.842 Angstrom, and the density Laplacian plot (-del(2)rho) reveals that the extent of H ... Si interaction is quite weak, with little sign of competition for the metal-to-ligand back-donation. Comparisons with the unchelated model complex RuH2(PH3)(2)(H ... SiH3)(2) show that the chelation causes a weaker H ... Si interaction, with an H ... Si distance of the unchelated complex of similar to 1.750 Angstrom.

Reactions of TpRuH(CH3CN)(PPh3) with free silanes HSiR3 (R-3 = Et-3, (EtO)(3), Ph-3, HEt2, HPh2, and H2Ph) in THF yield the complexes TpRu(PPh3)(H)(eta(2)-HSiR3), the formulation of which is inferred from NMR spectroscopic data. The chemical equivalence of the two hydrogen atoms of TpRu(PPh3)(H)(eta(2)-HSiR3) down to -100 degrees C is attributed to rapid fluxionality between the two, i.e., TpRu(PPh3)(H-a)(eta(2)-HbSiR3) reversible arrow TpRu(PPh3)(H-b)(eta(2)-HaSiR3). Molecular orbital calculations at the B3LYP level have been performed to investigate the stereochemistry and the interconversion processes of various structural isomers for TpRu(PPh3)(H)(eta(2)-HSiR3). The results further support the existence of a eta(2)-silane formulation for these complexes. Two stable structures, with a nonclassical eta(2)-silane ligand, have been found. These two structural isomers are found to be in equilibrium with a low reaction barrier (7.5 kcal/mol). The interconversion between the enantiomeric pair of the most stable structure has almost no reaction barrier (0.5 kcal/mol). Together with the experimental findings, a mechanistic cycle is proposed. The complexes TpRu(PPh3)(H)(eta(2)-HSiR3) react reversibly with pressurized H-2, CH3CN, and PPh3 to give TpRuH(Hz)(PPh3), TpRuH(CH3CN)(PPh3), and TpRuH(PPh3)(2), respectively.

The complex RuH2(PCy3)(2)(trans-kappa-eta(2)-H ... SiMe2-o-C6H4-SiMe2... H) exhibits a number of intriguing structural features, in particular the apparent trans configuration of the two H ... Si units, the nearly collinear axial trans-H-Ru-H bonds, and the adoption of a near-C-2v symmetry. Theoretical studies indicate that, in the experimental structure, the drastic distortion of the two H ... Si units avoids the competition, for sigma{*}back-donation. while strengthening both the axial Ru-H and the Ru-Si bonds through a favorable orbital interaction with the metal d-orbitals. Such distortion is enhanced by the presence of chelation. which forces a small Si-Ru-Si angle. The H ... Si interaction distance is 1.842 Angstrom, and the density Laplacian plot (-del(2)rho) reveals that the extent of H ... Si interaction is quite weak, with little sign of competition for the metal-to-ligand back-donation. Comparisons with the unchelated model complex RuH2(PH3)(2)(H ... SiH3)(2) show that the chelation causes a weaker H ... Si interaction, with an H ... Si distance of the unchelated complex of similar to 1.750 Angstrom.

The complex RuH2(PCy3)(2)(trans-kappa-eta(2)-H ... SiMe2-o-C6H4-SiMe2... H) exhibits a number of intriguing structural features, in particular the apparent trans configuration of the two H ... Si units, the nearly collinear axial trans-H-Ru-H bonds, and the adoption of a near-C-2v symmetry. Theoretical studies indicate that, in the experimental structure, the drastic distortion of the two H ... Si units avoids the competition, for sigma{*}back-donation. while strengthening both the axial Ru-H and the Ru-Si bonds through a favorable orbital interaction with the metal d-orbitals. Such distortion is enhanced by the presence of chelation. which forces a small Si-Ru-Si angle. The H ... Si interaction distance is 1.842 Angstrom, and the density Laplacian plot (-del(2)rho) reveals that the extent of H ... Si interaction is quite weak, with little sign of competition for the metal-to-ligand back-donation. Comparisons with the unchelated model complex RuH2(PH3)(2)(H ... SiH3)(2) show that the chelation causes a weaker H ... Si interaction, with an H ... Si distance of the unchelated complex of similar to 1.750 Angstrom.

Reactions of TpRuH(CH3CN)(PPh3) with free silanes HSiR3 (R-3 = Et-3, (EtO)(3), Ph-3, HEt2, HPh2, and H2Ph) in THF yield the complexes TpRu(PPh3)(H)(eta(2)-HSiR3), the formulation of which is inferred from NMR spectroscopic data. The chemical equivalence of the two hydrogen atoms of TpRu(PPh3)(H)(eta(2)-HSiR3) down to -100 degrees C is attributed to rapid fluxionality between the two, i.e., TpRu(PPh3)(H-a)(eta(2)-HbSiR3) reversible arrow TpRu(PPh3)(H-b)(eta(2)-HaSiR3). Molecular orbital calculations at the B3LYP level have been performed to investigate the stereochemistry and the interconversion processes of various structural isomers for TpRu(PPh3)(H)(eta(2)-HSiR3). The results further support the existence of a eta(2)-silane formulation for these complexes. Two stable structures, with a nonclassical eta(2)-silane ligand, have been found. These two structural isomers are found to be in equilibrium with a low reaction barrier (7.5 kcal/mol). The interconversion between the enantiomeric pair of the most stable structure has almost no reaction barrier (0.5 kcal/mol). Together with the experimental findings, a mechanistic cycle is proposed. The complexes TpRu(PPh3)(H)(eta(2)-HSiR3) react reversibly with pressurized H-2, CH3CN, and PPh3 to give TpRuH(Hz)(PPh3), TpRuH(CH3CN)(PPh3), and TpRuH(PPh3)(2), respectively.

The nature of possible H ... SiR3 interligand interactions in the complexes MCp2XH(SiR3) (M = Nb, Ta; X = SiR3, Cl, H, CH3) has been studied by ab initio calculations at the MP2 level. The optimized structure of NbCp2(SiClH2)H(SiClH2) shows symmetric displacements of the silyl ligands about the hydride, with a H ... Si distance of 2.180 Angstrom, consistent with the experimental findings. Analysis of the Laplacian of the valence electron density (-del(2) rho) reveals significant polarization of the electron density around H toward both silicon centers (without an observable H ... Si bond path), indicating the presence of weak H ... Si interaction. The extent of the H ... Si interaction can be increased by replacing one of the SiR3 ligands by a halide or CH3 and using halide-substituted silyl ligands. An extreme case is MCp2ClH(SiClnH3-n), n greater than or equal to 1, with H ... Si interaction distances less than 2.0 Angstrom, and a curved H-Si bond path is observed in each of the respective Laplacian plots. Moreover, an in-plane Cl substituent on silicon causes a more drastic increase of the H ... Si interaction than an out-of plane chloride due to favorable orbital interactions. For the tantalum analogue TaCp2(SiH3)H(SiH3), the theoretical results indicate a symmetric structure similar to NbCp2(SiClH2)H(SiClH2) rather than unsymmetric (with one H ... Si distance of similar to 1.6 Angstrom), as suggested by experimental X-ray results. Other theoretical evidences also support the symmetric C-2 upsilon structure of the complex. The "nonclassical" H ... Si coordination in the Cl- and CH3-substituted complexes suggest a new type of eta(2)-silane complexes stabilized by sigma-withdrawing effects, without the presence of any strong pi-acceptor like CO and PR3.

The nature of possible H ... SiR3 interligand interactions in the complexes MCp2XH(SiR3) (M = Nb, Ta; X = SiR3, Cl, H, CH3) has been studied by ab initio calculations at the MP2 level. The optimized structure of NbCp2(SiClH2)H(SiClH2) shows symmetric displacements of the silyl ligands about the hydride, with a H ... Si distance of 2.180 Angstrom, consistent with the experimental findings. Analysis of the Laplacian of the valence electron density (-del(2) rho) reveals significant polarization of the electron density around H toward both silicon centers (without an observable H ... Si bond path), indicating the presence of weak H ... Si interaction. The extent of the H ... Si interaction can be increased by replacing one of the SiR3 ligands by a halide or CH3 and using halide-substituted silyl ligands. An extreme case is MCp2ClH(SiClnH3-n), n greater than or equal to 1, with H ... Si interaction distances less than 2.0 Angstrom, and a curved H-Si bond path is observed in each of the respective Laplacian plots. Moreover, an in-plane Cl substituent on silicon causes a more drastic increase of the H ... Si interaction than an out-of plane chloride due to favorable orbital interactions. For the tantalum analogue TaCp2(SiH3)H(SiH3), the theoretical results indicate a symmetric structure similar to NbCp2(SiClH2)H(SiClH2) rather than unsymmetric (with one H ... Si distance of similar to 1.6 Angstrom), as suggested by experimental X-ray results. Other theoretical evidences also support the symmetric C-2 upsilon structure of the complex. The "nonclassical" H ... Si coordination in the Cl- and CH3-substituted complexes suggest a new type of eta(2)-silane complexes stabilized by sigma-withdrawing effects, without the presence of any strong pi-acceptor like CO and PR3.

The nature of possible H ... SiR3 interligand interactions in the complexes MCp2XH(SiR3) (M = Nb, Ta; X = SiR3, Cl, H, CH3) has been studied by ab initio calculations at the MP2 level. The optimized structure of NbCp2(SiClH2)H(SiClH2) shows symmetric displacements of the silyl ligands about the hydride, with a H ... Si distance of 2.180 Angstrom, consistent with the experimental findings. Analysis of the Laplacian of the valence electron density (-del(2) rho) reveals significant polarization of the electron density around H toward both silicon centers (without an observable H ... Si bond path), indicating the presence of weak H ... Si interaction. The extent of the H ... Si interaction can be increased by replacing one of the SiR3 ligands by a halide or CH3 and using halide-substituted silyl ligands. An extreme case is MCp2ClH(SiClnH3-n), n greater than or equal to 1, with H ... Si interaction distances less than 2.0 Angstrom, and a curved H-Si bond path is observed in each of the respective Laplacian plots. Moreover, an in-plane Cl substituent on silicon causes a more drastic increase of the H ... Si interaction than an out-of plane chloride due to favorable orbital interactions. For the tantalum analogue TaCp2(SiH3)H(SiH3), the theoretical results indicate a symmetric structure similar to NbCp2(SiClH2)H(SiClH2) rather than unsymmetric (with one H ... Si distance of similar to 1.6 Angstrom), as suggested by experimental X-ray results. Other theoretical evidences also support the symmetric C-2 upsilon structure of the complex. The "nonclassical" H ... Si coordination in the Cl- and CH3-substituted complexes suggest a new type of eta(2)-silane complexes stabilized by sigma-withdrawing effects, without the presence of any strong pi-acceptor like CO and PR3.

The titanocene-acetylene complex TiCp(2)(eta(2)-trans-(t)BuC=CSiHMe(2)) shows a significant bending of the H-Si bond toward the metal center Ab initio theoretical calculations are used to clarify the interplay between the coordinated C=C and H-Si bonds. Analysis of the density Laplacian suggests that the complex is better formulated as having a d(2) metal center. The complex is another elegant example manifesting the strong sigma{*}-accepting nature of the H-Si bond.

The titanocene-acetylene complex TiCp(2)(eta(2)-trans-(t)BuC=CSiHMe(2)) shows a significant bending of the H-Si bond toward the metal center Ab initio theoretical calculations are used to clarify the interplay between the coordinated C=C and H-Si bonds. Analysis of the density Laplacian suggests that the complex is better formulated as having a d(2) metal center. The complex is another elegant example manifesting the strong sigma{*}-accepting nature of the H-Si bond.

The titanocene-acetylene complex TiCp(2)(eta(2)-trans-(t)BuC=CSiHMe(2)) shows a significant bending of the H-Si bond toward the metal center Ab initio theoretical calculations are used to clarify the interplay between the coordinated C=C and H-Si bonds. Analysis of the density Laplacian suggests that the complex is better formulated as having a d(2) metal center. The complex is another elegant example manifesting the strong sigma{*}-accepting nature of the H-Si bond.

The recent characterisation of short contacts between chloroform solvate molecules and the C-C triple bond of gold ethynides has prompted a theoretical investigation of the strength of C-H ...pi interactions. Extensive ab initio and density functional theory calculations have been performed on a variety of model systems displaying a T-shaped C-H ...pi motif. The interaction of ethyne, C2H2, with a variety of small proton donor molecules (HCN, CH4-nCln, n = 0-3) is invariably found to be weak (Delta E(int) < 10 kJ mol(-1)). Replacement of the two acetylenic protons with more electron-donating sodium atoms increases the electron density in the C-C pi bond and results in a substantial increase in the interaction with the proton donor. The calculated interaction energies rise to as much as 60 kJ mol(-1) in the case of C2Na2 ... CHCl3. The interaction of CHCl3 with a model gold ethynide, H3PAuCCAuPH3, is intermediate between these two extremes, ab initio and density functional calculations both giving estimates of ca. 25 kJ mol(-1) comparable to a reasonably strong hydrogen bond. The unusually strong C-H ...pi interactions in the gold ethynide arise directly as a consequence of the electron-donating properties of the AuPR(3) fragment and are fundamentally different to the much weaker C-H ...pi interactions in purely organic systems.

The recent characterisation of short contacts between chloroform solvate molecules and the C-C triple bond of gold ethynides has prompted a theoretical investigation of the strength of C-H ...pi interactions. Extensive ab initio and density functional theory calculations have been performed on a variety of model systems displaying a T-shaped C-H ...pi motif. The interaction of ethyne, C2H2, with a variety of small proton donor molecules (HCN, CH4-nCln, n = 0-3) is invariably found to be weak (Delta E(int) < 10 kJ mol(-1)). Replacement of the two acetylenic protons with more electron-donating sodium atoms increases the electron density in the C-C pi bond and results in a substantial increase in the interaction with the proton donor. The calculated interaction energies rise to as much as 60 kJ mol(-1) in the case of C2Na2 ... CHCl3. The interaction of CHCl3 with a model gold ethynide, H3PAuCCAuPH3, is intermediate between these two extremes, ab initio and density functional calculations both giving estimates of ca. 25 kJ mol(-1) comparable to a reasonably strong hydrogen bond. The unusually strong C-H ...pi interactions in the gold ethynide arise directly as a consequence of the electron-donating properties of the AuPR(3) fragment and are fundamentally different to the much weaker C-H ...pi interactions in purely organic systems.

The recent characterisation of short contacts between chloroform solvate molecules and the C-C triple bond of gold ethynides has prompted a theoretical investigation of the strength of C-H ...pi interactions. Extensive ab initio and density functional theory calculations have been performed on a variety of model systems displaying a T-shaped C-H ...pi motif. The interaction of ethyne, C2H2, with a variety of small proton donor molecules (HCN, CH4-nCln, n = 0-3) is invariably found to be weak (Delta E(int) < 10 kJ mol(-1)). Replacement of the two acetylenic protons with more electron-donating sodium atoms increases the electron density in the C-C pi bond and results in a substantial increase in the interaction with the proton donor. The calculated interaction energies rise to as much as 60 kJ mol(-1) in the case of C2Na2 ... CHCl3. The interaction of CHCl3 with a model gold ethynide, H3PAuCCAuPH3, is intermediate between these two extremes, ab initio and density functional calculations both giving estimates of ca. 25 kJ mol(-1) comparable to a reasonably strong hydrogen bond. The unusually strong C-H ...pi interactions in the gold ethynide arise directly as a consequence of the electron-donating properties of the AuPR(3) fragment and are fundamentally different to the much weaker C-H ...pi interactions in purely organic systems.

Huckel model calculations have been performed for small fullerene cages with 20-50 atoms. The closed-shell electronic structures for the small cages are emphasized. The relatively high stability of C-24, C-28, C-32, C-44 and C-50 clusters observed in the early laser vaporization experiments is explained. These clusters have pseudo closed-shell or half-filled electronic structures with a relatively large HOMO-LUMO gap. Based on the Huckel results, we propose a large number of other possible stable clusters formed by adding hydrogens, replacing carbons with other atoms which have an appropriate number of valence electrons, or encapsulating metal atoms capable of donating a given number of valence electrons.

Huckel model calculations have been performed for small fullerene cages with 20-50 atoms. The closed-shell electronic structures for the small cages are emphasized. The relatively high stability of C-24, C-28, C-32, C-44 and C-50 clusters observed in the early laser vaporization experiments is explained. These clusters have pseudo closed-shell or half-filled electronic structures with a relatively large HOMO-LUMO gap. Based on the Huckel results, we propose a large number of other possible stable clusters formed by adding hydrogens, replacing carbons with other atoms which have an appropriate number of valence electrons, or encapsulating metal atoms capable of donating a given number of valence electrons.

Huckel model calculations have been performed for small fullerene cages with 20-50 atoms. The closed-shell electronic structures for the small cages are emphasized. The relatively high stability of C-24, C-28, C-32, C-44 and C-50 clusters observed in the early laser vaporization experiments is explained. These clusters have pseudo closed-shell or half-filled electronic structures with a relatively large HOMO-LUMO gap. Based on the Huckel results, we propose a large number of other possible stable clusters formed by adding hydrogens, replacing carbons with other atoms which have an appropriate number of valence electrons, or encapsulating metal atoms capable of donating a given number of valence electrons.