Alessandro Pasini - Academia.edu (original) (raw)
Papers by Alessandro Pasini
Inorg Chem, 2010
The relevance of cis and trans influences of some anionic ligands X and Y in cis-[PtX 2 (PPh 3 ) ... more The relevance of cis and trans influences of some anionic ligands X and Y in cis-[PtX 2 (PPh 3 ) 2 ] and cis-[PtXY(PPh 3 ) 2 ] complexes have been studied by the X-ray crystal structures of several derivatives (X 2 = (AcO) 2 (3), (NO 3 ) 2 (5), Br 2 (7), I 2 (11); and XY = Cl(AcO) (2), Cl(NO 3 ) (4), and Cl(NO 2 ) (13)), density functional theory (DFT) calculations, and one bond Pt-P coupling constants, 1 J PtP . The latter have allowed an evaluation of the relative magnitude of both influences. It is concluded that such influences act in a cooperative way and that the cis influence is not irrelevant when rationalizing the 1 J PtP values, as well as the experimental Pt-P bond distances. On the contrary, in the optimized geometries, evaluated through B3LYP/def2-SVP calculations, the cis influence was not observed, except for compounds ClPh (21), Ph 2 (22), and, to a lesser extent, Cl(NO 2 ) (13) and (NO 2 ) 2 (14). A natural bond order analysis on the optimized structures, however, has shown how the cis influence can be related to the s-character of the Pt hybrid orbital involved in the Pt-P bonds and the net atomic charge on Pt. We have also found that in the X-ray structures of cis-[PtX 2 (PPh 3 ) 2 ] complexes the two Pt-X and the two Pt-P bond lengths are different each other and are related to the conformation of the phosphine groups, rather than to the crystal packing, since this feature is observed also in the optimized geometries.
![Research paper thumbnail of Quantification of cis and trans influences in [PtX(PPh3)3]+ complexes. A 31P NMR study](https://attachments.academia-assets.com/44687798/thumbnails/1.jpg)
](Inorganica Chimica Acta, 2010
Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phos... more Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phosphine complexes a b s t r a c t In [PtX(PPh 3 ) 3 ] + complexes (X = F, Cl, Br, I, AcO, NO 3 , NO 2 , H, Me) the mutual cis and trans influences of the PPh 3 groups can be considered constants in the first place, therefore the one bond Pt-P coupling constants of P (cis) and P (trans) reflect the cis and trans influences of X. The compounds [PtBr(PPh 3 ) 3 ]((6b) have been newly synthesised and the crystal structures of 2 and 4ÁCH 2 Cl 2 Á0.25C 3 H 6 O have been determined. From the 1 J PtP values of all compounds we have deduced the series: I > Br > Cl > NO 3 > ONO > F > AcO > NO 2 > H > Me (cis influence) and Me > H > NO 2 > A-cO > I > ONO > Br > Cl > F > NO 3 (trans influence). These sequences are like those obtained for the (neutral) cis-and trans-[PtClX(PPh 3 ) 2 ] derivatives, showing that there is no dependence on the charge of the complexes. On the contrary, the weights of both influences, relative to those of X = Cl, were found to depend on the charge and nature of the complex.
Journal of Inorganic and Nuclear Chemistry, 1972
The cis and the trans influences are important tools to rationalize the bond strengths in complex... more The cis and the trans influences are important tools to rationalize the bond strengths in complexes. In cis/trans-[Pt II XY(PPh 3 ) 2 ] compounds (X and Y are anionic ligands) the variations of the Pt-P bond strengths can be related to the 1 J PtP values, which depend on both the cis and trans influences of X and Y. Analysing the coupling constants of a series of cis and trans-[Pt II XY(PPh 3 ) 2 ] compounds these influences can be rationalized and quantified. 1 The structural trans and cis influences are less manifest, as shown by several crystal structures, which have been determined. A theoretical study will also be described, in order to fully comprehend these systems. 1. some already published results in: Rigamonti, L.; Manassero, C.; Rusconi, M.; Manassero, M.; Pasini, A. Dalton Trans. 2009, 1206-1213.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
A couple of small paintings on wood, property of the National Gallery of Bologna and attributed t... more A couple of small paintings on wood, property of the National Gallery of Bologna and attributed to Gentile da Fabriano, have been analyzed by means of different diagnostic non-destructive techniques in order to have a complete characterization of their conservation state. Adopted techniques are X-ray fluorescence, infrared reflection imaging, radiography and computed tomography (CT). In this work we will focus mainly on results obtained with CT, which was carried out with a CT system developed by the authors at the Physics Department of the University of Bologna. The CT system has already been used for the full-volume examination of archaeological samples and works of art and mainly consists of a cone-beam X-ray source, a rotational stage for sample manipulation and a Gd 2 O 2 S:Tb scintillator screen, optically coupled to a CCD camera. The CT investigation has given us important information on the conservation state of the two tables and on the spatial distribution of the different materials and pigments, besides providing an evidence of a particular technique used by the painter for outlining the figures of the Saint Apostles. r
In the last few decades, the research in the nonlinear optical (NLO) field has received a strong ... more In the last few decades, the research in the nonlinear optical (NLO) field has received a strong push toward the synthesis and the study of new materials, especially inorganic and organometallic derivatives, due to the great possibility to modulate their electronic behaviour. Our research group has started a systematic study of metal complexes with tetradentate Schiff base ligands ('salen' analogues), that has led to the complete study and comprehension of the electronic and nonlinear optical features of unsymmetrical salen-type copper(II) complexes 1, substituted along the x-axis with electron-donor D and acceptor A groups. 1 With the same template synthetic procedure, compounds 2 with chiral diamines (1,2-diaminocyclohexane and 1,2-diphenyl ethylendiamine) have been obtained and studied. The understanding of the role of the metal centre in such systems is quite important, due to its central position in the metallorganic framework. A template path for the synthesis of nickel(II) unsymmetrically substituted derivatives with 1,3-diaminopropane (tn) has been detected 2 and used to synthesise compounds 3, and the results obtained will be presented. The monocondensation product of o-phen and 5-NO 2 -salicylaldehyde has allowed the synthesis of a new series of unsymmetrically substituted tetradentate Schiff base ligands. The results obtained on their metal complexes 4 will be outlined. A O N (CH 2 ) n N O D Cu A O N N O D Ni O 2 N O N N O D M x y A = H, NO 2 ; D = H, Me, OMe, NMe 2 ; n = 2, 3 A = H, NO 2 ; D = H, Me, OMe, NMe 2 D = H, Me, OMe, NMe 2 ; M = Ni, Cu, Zn, etc... A O N N O D Cu A = H, NO 2 ; D = H, Me, OMe, NMe 2 ; R = Ph, (CH 2 ) 4 * * R R 1 2 3 4 1. Rigamonti, L.; Demartin, F.; Forni, A.; Righetto, S.; Pasini, A.
Optical Methods for Arts and Archaeology, 2005
Computed Tomography (CT) is one of the principal non-invasive techniques for the investigation of... more Computed Tomography (CT) is one of the principal non-invasive techniques for the investigation of the inner structure of works of art. The main advantage of using CT is that it provides high resolution 3D information of the analyzed object. CT of large objects can be hampered by the long time needed and by the difficulties regarding the experimental arrangements required.
Journal of the Chemical Society, Dalton Transactions, 1977
ABSTRACT The synthesis and properties of palladium(II) and platinum(II) complexes with quadrident... more ABSTRACT The synthesis and properties of palladium(II) and platinum(II) complexes with quadridentate Schiff bases derived from the condensation of salicylaldehyde and (R)-1,2-diamines are described. The ligand conformation of the platinum(II) complexes is discussed on the basis of the circular dichroism and the 1H n.m.r. spectra. The anomalous patterns of the circular dichroism spectra of palladium(II) derivatives are also reported.
IEEE Nuclear Science Symposium Conference Record, 2005, 2005
Computed tomography (CT) is becoming a very useful non-destructive testing technique, in the indu... more Computed tomography (CT) is becoming a very useful non-destructive testing technique, in the industrial field, since it permits the detection of small inner defects in a reliable and accurate way. In order to get very good performance, in terms of image contrast and spatial resolution, the configuration of the tomography system has to be optimized carefully. Monte Carlo simulations can
Journal of Inorganic and Nuclear Chemistry, 1972
The synthesis and properties of uranyl complexes with tetradentate ligands of formula U O~ (saldi... more The synthesis and properties of uranyl complexes with tetradentate ligands of formula U O~ (saldiamine). L (where saldiamine is the Schiff base N,N'diamine bis(salicylideneimine), L is a solvent molecule and the diamines are ethylenediamine, (+) propylenediamine, (+) and meso butanediamine, (t) and meso cyclohexanediamine, (-) and meso stilbenediamine) are reported. I.R., electronic and circular dichroism spectra are also discussed.
O3A: Optics for Arts, Architecture, and Archaeology, 2007
X-ray cone-beam Computed Tomography is a powerful tool for the non-destructive investigation of t... more X-ray cone-beam Computed Tomography is a powerful tool for the non-destructive investigation of the inner structure of works of art. With regard to Cultural Heritage conservation, different kinds of objects have to be inspected in order to acquire significant information such as the manufacturing technique or the presence of defects and damages. The knowledge of these features is very useful
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006
Intra Operative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionis... more Intra Operative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionising radiation to the cancer tissue, after tumour ablation, during surgery, while reducing the exposure of normal surrounding tissue. The Novac7 is a new linear accelerator expressly conceived to perform in the operating theatre. This accelerator supplies electron beams with high dose rate (up
Medical & Biological Engineering & Computing, 2005
Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided ma... more Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided manufacturing techniques are opening new and interesting prospects for medical devices and tissue engineering, especially for hard tissues such as bone. The development of a bone high-resolution scaffold prototype using these techniques is described. The results testify to the fidelity existing between microtomographic reconstruction and CAD. Furthermore, stereolithographic manufacturing of this scaffold, which possesses a high degree of similarity to the starting model as monitored by morphological evaluations (mean diameter 569 +/- 147 microm), represents a promising result for regenerative medicine applications.
International Journal of Mineral Processing, 2005
The size distribution of the diamonds in a kimberlitic rock is a negative exponential function-i.... more The size distribution of the diamonds in a kimberlitic rock is a negative exponential function-i.e., the frequency of large diamonds diminishes exponentially with increasing size. The number of microdiamonds in narrow fine sizes allows predicting the probability of discovering coarser valuable diamonds. For deposit evaluation, the microdiamonds are recovered in the solid residue of the leaching of some hundreds kilograms of rock samples. Computed tomography (CT) systemsbased on nano-and micro-focus X-ray sources and high-resolution detectors-capable of scanning drill-hole cores have been indicated as a possible practicable alternative to leaching for microdiamond studies. A simple model is developed that allows valuating the size of the microdiamond detectable with a given X-ray tube spot size and detector Modulation Transfer Function (MTF). Basically, the model describes the diamond as a nodule of known attenuation, projects it on the detector plane with a given magnification, resamples the magnified nodule according to the detector pixel array, calculates the frequency content of the nodule on the detector plane by FFT, composes the frequency content with the overall MTF of the system and by FFT À1 recalculates the object. By comparing the reconstructed object with the original one, the lost in attenuation and the blurring due to the radiography system can be evaluated.
International Journal of Computer Assisted Radiology and Surgery, 2008
Objectives The aim of this study is to investigate the effect of head motion on the reconstructi... more Objectives The aim of this study is to investigate the effect of head motion on the reconstruction image quality in relation to patient positioning in dental cone-beam computed tomography (CBCT) systems. This study should be intended as the first step to evaluate the effect of the head movements also in more stringent conditions. Methods Head motion was monitored using an EasyTrack-500 system
Inorganica Chimica Acta, 1976
Inorganica Chimica Acta, 1997
The metal complexes of deprotonated N,N′-bis(2-hydroxybenzylidene)arylmethanedimines show a stron... more The metal complexes of deprotonated N,N′-bis(2-hydroxybenzylidene)arylmethanedimines show a strong preference for tetrahedral structures. Oxidation of the Co(II) derivatives gives compounds with S = 1.
![Research paper thumbnail of Quantification of cis and trans influences in [PtX(PPh3)3]+ complexes. A 31P NMR study](https://attachments.academia-assets.com/44687791/thumbnails/1.jpg)
](Inorganica Chimica Acta, 2010
Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phos... more Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phosphine complexes a b s t r a c t In [PtX(PPh 3 ) 3 ] + complexes (X = F, Cl, Br, I, AcO, NO 3 , NO 2 , H, Me) the mutual cis and trans influences of the PPh 3 groups can be considered constants in the first place, therefore the one bond Pt-P coupling constants of P (cis) and P (trans) reflect the cis and trans influences of X. The compounds [PtBr(PPh 3 ) 3 ]((6b) have been newly synthesised and the crystal structures of 2 and 4ÁCH 2 Cl 2 Á0.25C 3 H 6 O have been determined. From the 1 J PtP values of all compounds we have deduced the series: I > Br > Cl > NO 3 > ONO > F > AcO > NO 2 > H > Me (cis influence) and Me > H > NO 2 > A-cO > I > ONO > Br > Cl > F > NO 3 (trans influence). These sequences are like those obtained for the (neutral) cis-and trans-[PtClX(PPh 3 ) 2 ] derivatives, showing that there is no dependence on the charge of the complexes. On the contrary, the weights of both influences, relative to those of X = Cl, were found to depend on the charge and nature of the complex.
Inorganica Chimica Acta, 2005
ABSTRACT The interaction of an excess of the title ligands L− with the cis-Pt(phos)2 moieties giv... more ABSTRACT The interaction of an excess of the title ligands L− with the cis-Pt(phos)2 moieties gives compounds a–bcis-[Pt(L-O)2(phos)2] (a, phos = P(Ph)3; b, phos = 1/2 dppe), in which O- is preferred to S-coordination. Such preference is confirmed by the fact that the same products are obtained by reaction of excess of L− with the previously reported a–d complexes [Pt(L-O,S)(phos)2]+, (c, phos = PPh3, d, phos = 1/2 dppe), for which chelate ring opening occurs with rupture of Pt–S rather than Pt–O bonds. Compound a can be obtained also by oxidative addition of HL to [Pt(PPh3)3]. The Pt–O bonds in compounds a–d are stable towards substitution by Me2SO, pyridine and tetramethylthiourea. Substitution of L’s occurs with N,N′-diethyldithiocarbamate, which forms a very stable chelate with Pt(II). Thiourea and N,N′-dimethylthiourea also react, because they give rise to cyclometallated products [Pt(phos)2(NRC(S)NHR)]+ (R = H, CH3), with one ionised thioamido group, as revealed by an X-ray investigation of [Pt(PPh3)2(NHC(S)NH2)]+. The preference of O versus S coordination, as well as the stability of the Pt–O bonds, are discussed in terms of antisymbiosis.
Inorg Chem, 2010
The relevance of cis and trans influences of some anionic ligands X and Y in cis-[PtX 2 (PPh 3 ) ... more The relevance of cis and trans influences of some anionic ligands X and Y in cis-[PtX 2 (PPh 3 ) 2 ] and cis-[PtXY(PPh 3 ) 2 ] complexes have been studied by the X-ray crystal structures of several derivatives (X 2 = (AcO) 2 (3), (NO 3 ) 2 (5), Br 2 (7), I 2 (11); and XY = Cl(AcO) (2), Cl(NO 3 ) (4), and Cl(NO 2 ) (13)), density functional theory (DFT) calculations, and one bond Pt-P coupling constants, 1 J PtP . The latter have allowed an evaluation of the relative magnitude of both influences. It is concluded that such influences act in a cooperative way and that the cis influence is not irrelevant when rationalizing the 1 J PtP values, as well as the experimental Pt-P bond distances. On the contrary, in the optimized geometries, evaluated through B3LYP/def2-SVP calculations, the cis influence was not observed, except for compounds ClPh (21), Ph 2 (22), and, to a lesser extent, Cl(NO 2 ) (13) and (NO 2 ) 2 (14). A natural bond order analysis on the optimized structures, however, has shown how the cis influence can be related to the s-character of the Pt hybrid orbital involved in the Pt-P bonds and the net atomic charge on Pt. We have also found that in the X-ray structures of cis-[PtX 2 (PPh 3 ) 2 ] complexes the two Pt-X and the two Pt-P bond lengths are different each other and are related to the conformation of the phosphine groups, rather than to the crystal packing, since this feature is observed also in the optimized geometries.
Inorganica Chimica Acta, 2010
Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phos... more Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phosphine complexes a b s t r a c t In [PtX(PPh 3 ) 3 ] + complexes (X = F, Cl, Br, I, AcO, NO 3 , NO 2 , H, Me) the mutual cis and trans influences of the PPh 3 groups can be considered constants in the first place, therefore the one bond Pt-P coupling constants of P (cis) and P (trans) reflect the cis and trans influences of X. The compounds [PtBr(PPh 3 ) 3 ]((6b) have been newly synthesised and the crystal structures of 2 and 4ÁCH 2 Cl 2 Á0.25C 3 H 6 O have been determined. From the 1 J PtP values of all compounds we have deduced the series: I > Br > Cl > NO 3 > ONO > F > AcO > NO 2 > H > Me (cis influence) and Me > H > NO 2 > A-cO > I > ONO > Br > Cl > F > NO 3 (trans influence). These sequences are like those obtained for the (neutral) cis-and trans-[PtClX(PPh 3 ) 2 ] derivatives, showing that there is no dependence on the charge of the complexes. On the contrary, the weights of both influences, relative to those of X = Cl, were found to depend on the charge and nature of the complex.
Journal of Inorganic and Nuclear Chemistry, 1972
The cis and the trans influences are important tools to rationalize the bond strengths in complex... more The cis and the trans influences are important tools to rationalize the bond strengths in complexes. In cis/trans-[Pt II XY(PPh 3 ) 2 ] compounds (X and Y are anionic ligands) the variations of the Pt-P bond strengths can be related to the 1 J PtP values, which depend on both the cis and trans influences of X and Y. Analysing the coupling constants of a series of cis and trans-[Pt II XY(PPh 3 ) 2 ] compounds these influences can be rationalized and quantified. 1 The structural trans and cis influences are less manifest, as shown by several crystal structures, which have been determined. A theoretical study will also be described, in order to fully comprehend these systems. 1. some already published results in: Rigamonti, L.; Manassero, C.; Rusconi, M.; Manassero, M.; Pasini, A. Dalton Trans. 2009, 1206-1213.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
A couple of small paintings on wood, property of the National Gallery of Bologna and attributed t... more A couple of small paintings on wood, property of the National Gallery of Bologna and attributed to Gentile da Fabriano, have been analyzed by means of different diagnostic non-destructive techniques in order to have a complete characterization of their conservation state. Adopted techniques are X-ray fluorescence, infrared reflection imaging, radiography and computed tomography (CT). In this work we will focus mainly on results obtained with CT, which was carried out with a CT system developed by the authors at the Physics Department of the University of Bologna. The CT system has already been used for the full-volume examination of archaeological samples and works of art and mainly consists of a cone-beam X-ray source, a rotational stage for sample manipulation and a Gd 2 O 2 S:Tb scintillator screen, optically coupled to a CCD camera. The CT investigation has given us important information on the conservation state of the two tables and on the spatial distribution of the different materials and pigments, besides providing an evidence of a particular technique used by the painter for outlining the figures of the Saint Apostles. r
In the last few decades, the research in the nonlinear optical (NLO) field has received a strong ... more In the last few decades, the research in the nonlinear optical (NLO) field has received a strong push toward the synthesis and the study of new materials, especially inorganic and organometallic derivatives, due to the great possibility to modulate their electronic behaviour. Our research group has started a systematic study of metal complexes with tetradentate Schiff base ligands ('salen' analogues), that has led to the complete study and comprehension of the electronic and nonlinear optical features of unsymmetrical salen-type copper(II) complexes 1, substituted along the x-axis with electron-donor D and acceptor A groups. 1 With the same template synthetic procedure, compounds 2 with chiral diamines (1,2-diaminocyclohexane and 1,2-diphenyl ethylendiamine) have been obtained and studied. The understanding of the role of the metal centre in such systems is quite important, due to its central position in the metallorganic framework. A template path for the synthesis of nickel(II) unsymmetrically substituted derivatives with 1,3-diaminopropane (tn) has been detected 2 and used to synthesise compounds 3, and the results obtained will be presented. The monocondensation product of o-phen and 5-NO 2 -salicylaldehyde has allowed the synthesis of a new series of unsymmetrically substituted tetradentate Schiff base ligands. The results obtained on their metal complexes 4 will be outlined. A O N (CH 2 ) n N O D Cu A O N N O D Ni O 2 N O N N O D M x y A = H, NO 2 ; D = H, Me, OMe, NMe 2 ; n = 2, 3 A = H, NO 2 ; D = H, Me, OMe, NMe 2 D = H, Me, OMe, NMe 2 ; M = Ni, Cu, Zn, etc... A O N N O D Cu A = H, NO 2 ; D = H, Me, OMe, NMe 2 ; R = Ph, (CH 2 ) 4 * * R R 1 2 3 4 1. Rigamonti, L.; Demartin, F.; Forni, A.; Righetto, S.; Pasini, A.
Optical Methods for Arts and Archaeology, 2005
Computed Tomography (CT) is one of the principal non-invasive techniques for the investigation of... more Computed Tomography (CT) is one of the principal non-invasive techniques for the investigation of the inner structure of works of art. The main advantage of using CT is that it provides high resolution 3D information of the analyzed object. CT of large objects can be hampered by the long time needed and by the difficulties regarding the experimental arrangements required.
Journal of the Chemical Society, Dalton Transactions, 1977
ABSTRACT The synthesis and properties of palladium(II) and platinum(II) complexes with quadrident... more ABSTRACT The synthesis and properties of palladium(II) and platinum(II) complexes with quadridentate Schiff bases derived from the condensation of salicylaldehyde and (R)-1,2-diamines are described. The ligand conformation of the platinum(II) complexes is discussed on the basis of the circular dichroism and the 1H n.m.r. spectra. The anomalous patterns of the circular dichroism spectra of palladium(II) derivatives are also reported.
IEEE Nuclear Science Symposium Conference Record, 2005, 2005
Computed tomography (CT) is becoming a very useful non-destructive testing technique, in the indu... more Computed tomography (CT) is becoming a very useful non-destructive testing technique, in the industrial field, since it permits the detection of small inner defects in a reliable and accurate way. In order to get very good performance, in terms of image contrast and spatial resolution, the configuration of the tomography system has to be optimized carefully. Monte Carlo simulations can
Journal of Inorganic and Nuclear Chemistry, 1972
The synthesis and properties of uranyl complexes with tetradentate ligands of formula U O~ (saldi... more The synthesis and properties of uranyl complexes with tetradentate ligands of formula U O~ (saldiamine). L (where saldiamine is the Schiff base N,N'diamine bis(salicylideneimine), L is a solvent molecule and the diamines are ethylenediamine, (+) propylenediamine, (+) and meso butanediamine, (t) and meso cyclohexanediamine, (-) and meso stilbenediamine) are reported. I.R., electronic and circular dichroism spectra are also discussed.
O3A: Optics for Arts, Architecture, and Archaeology, 2007
X-ray cone-beam Computed Tomography is a powerful tool for the non-destructive investigation of t... more X-ray cone-beam Computed Tomography is a powerful tool for the non-destructive investigation of the inner structure of works of art. With regard to Cultural Heritage conservation, different kinds of objects have to be inspected in order to acquire significant information such as the manufacturing technique or the presence of defects and damages. The knowledge of these features is very useful
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006
Intra Operative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionis... more Intra Operative Radiation Therapy (IORT) is a technique based on delivery of a high dose of ionising radiation to the cancer tissue, after tumour ablation, during surgery, while reducing the exposure of normal surrounding tissue. The Novac7 is a new linear accelerator expressly conceived to perform in the operating theatre. This accelerator supplies electron beams with high dose rate (up
Medical & Biological Engineering & Computing, 2005
Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided ma... more Rapid prototyping, automatic image processing (computer-aided design (CAD)) and computer-aided manufacturing techniques are opening new and interesting prospects for medical devices and tissue engineering, especially for hard tissues such as bone. The development of a bone high-resolution scaffold prototype using these techniques is described. The results testify to the fidelity existing between microtomographic reconstruction and CAD. Furthermore, stereolithographic manufacturing of this scaffold, which possesses a high degree of similarity to the starting model as monitored by morphological evaluations (mean diameter 569 +/- 147 microm), represents a promising result for regenerative medicine applications.
International Journal of Mineral Processing, 2005
The size distribution of the diamonds in a kimberlitic rock is a negative exponential function-i.... more The size distribution of the diamonds in a kimberlitic rock is a negative exponential function-i.e., the frequency of large diamonds diminishes exponentially with increasing size. The number of microdiamonds in narrow fine sizes allows predicting the probability of discovering coarser valuable diamonds. For deposit evaluation, the microdiamonds are recovered in the solid residue of the leaching of some hundreds kilograms of rock samples. Computed tomography (CT) systemsbased on nano-and micro-focus X-ray sources and high-resolution detectors-capable of scanning drill-hole cores have been indicated as a possible practicable alternative to leaching for microdiamond studies. A simple model is developed that allows valuating the size of the microdiamond detectable with a given X-ray tube spot size and detector Modulation Transfer Function (MTF). Basically, the model describes the diamond as a nodule of known attenuation, projects it on the detector plane with a given magnification, resamples the magnified nodule according to the detector pixel array, calculates the frequency content of the nodule on the detector plane by FFT, composes the frequency content with the overall MTF of the system and by FFT À1 recalculates the object. By comparing the reconstructed object with the original one, the lost in attenuation and the blurring due to the radiography system can be evaluated.
International Journal of Computer Assisted Radiology and Surgery, 2008
Objectives The aim of this study is to investigate the effect of head motion on the reconstructi... more Objectives The aim of this study is to investigate the effect of head motion on the reconstruction image quality in relation to patient positioning in dental cone-beam computed tomography (CBCT) systems. This study should be intended as the first step to evaluate the effect of the head movements also in more stringent conditions. Methods Head motion was monitored using an EasyTrack-500 system
Inorganica Chimica Acta, 1976
Inorganica Chimica Acta, 1997
The metal complexes of deprotonated N,N′-bis(2-hydroxybenzylidene)arylmethanedimines show a stron... more The metal complexes of deprotonated N,N′-bis(2-hydroxybenzylidene)arylmethanedimines show a strong preference for tetrahedral structures. Oxidation of the Co(II) derivatives gives compounds with S = 1.
Inorganica Chimica Acta, 2010
Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phos... more Keywords: cis influence trans influence cis influence weight trans influence weight Platinum phosphine complexes a b s t r a c t In [PtX(PPh 3 ) 3 ] + complexes (X = F, Cl, Br, I, AcO, NO 3 , NO 2 , H, Me) the mutual cis and trans influences of the PPh 3 groups can be considered constants in the first place, therefore the one bond Pt-P coupling constants of P (cis) and P (trans) reflect the cis and trans influences of X. The compounds [PtBr(PPh 3 ) 3 ]((6b) have been newly synthesised and the crystal structures of 2 and 4ÁCH 2 Cl 2 Á0.25C 3 H 6 O have been determined. From the 1 J PtP values of all compounds we have deduced the series: I > Br > Cl > NO 3 > ONO > F > AcO > NO 2 > H > Me (cis influence) and Me > H > NO 2 > A-cO > I > ONO > Br > Cl > F > NO 3 (trans influence). These sequences are like those obtained for the (neutral) cis-and trans-[PtClX(PPh 3 ) 2 ] derivatives, showing that there is no dependence on the charge of the complexes. On the contrary, the weights of both influences, relative to those of X = Cl, were found to depend on the charge and nature of the complex.
Inorganica Chimica Acta, 2005
ABSTRACT The interaction of an excess of the title ligands L− with the cis-Pt(phos)2 moieties giv... more ABSTRACT The interaction of an excess of the title ligands L− with the cis-Pt(phos)2 moieties gives compounds a–bcis-[Pt(L-O)2(phos)2] (a, phos = P(Ph)3; b, phos = 1/2 dppe), in which O- is preferred to S-coordination. Such preference is confirmed by the fact that the same products are obtained by reaction of excess of L− with the previously reported a–d complexes [Pt(L-O,S)(phos)2]+, (c, phos = PPh3, d, phos = 1/2 dppe), for which chelate ring opening occurs with rupture of Pt–S rather than Pt–O bonds. Compound a can be obtained also by oxidative addition of HL to [Pt(PPh3)3]. The Pt–O bonds in compounds a–d are stable towards substitution by Me2SO, pyridine and tetramethylthiourea. Substitution of L’s occurs with N,N′-diethyldithiocarbamate, which forms a very stable chelate with Pt(II). Thiourea and N,N′-dimethylthiourea also react, because they give rise to cyclometallated products [Pt(phos)2(NRC(S)NHR)]+ (R = H, CH3), with one ionised thioamido group, as revealed by an X-ray investigation of [Pt(PPh3)2(NHC(S)NH2)]+. The preference of O versus S coordination, as well as the stability of the Pt–O bonds, are discussed in terms of antisymbiosis.