Pseudopolymorphism TGA/DTA methods a b s t r a c t Nickel(II) complexes of 6-bromopicolinic acid,... more Pseudopolymorphism TGA/DTA methods a b s t r a c t Nickel(II) complexes of 6-bromopicolinic acid, namely [Ni(6-Brpic) 2 (H 2 O) 2 ]Á3H 2 O (1) and [Ni(6-Brpic) 2 (H 2 O) 2 ]ÁH 2 O (2) were prepared and characterized by spectroscopic methods (IR), their molecular and crystal structures were determined by X-ray crystal structure analysis and their thermal stability by TGA/DTA methods. Compound 1 was prepared by reaction of nickel(II) nitrate and 6-bromopicolinic acid in aqueous solution at pH value of 8, while 2 was obtained by spontaneous recrystallization of 1 in its mother liquor during few months. These complexes are an example of pseudopolymorphs which differ in number of co-crystallized water molecules but both crystallize in the same crystal system (triclinic). X-ray structural analysis revealed octahedron as a coordination polyhedron in both 1 and 2 and the same N,O-chelated coordination mode of 6-bromopicolinic acid. The coordination sphere of nickel(II) ion is completed by two coordinated water molecules. These pseudopolymorphs differ in their crystal structures which are dominated by intermolecular O-HÁ Á ÁO hydrogen bonds and p-p stacking interactions in both cases. The infrared spectra of 1 and 2 are very similar so these pseudopolymorphs cannot be unambiguously distinguished by IR spectroscopy. Thermal methods confirm number of co-crystallized water molecules in both pseudopolymorphs.
Severe immunogenic and other debilitating human disorders potentially induced by protein aggregat... more Severe immunogenic and other debilitating human disorders potentially induced by protein aggregates have brought this phenomenon into the focus of biopharmaceutical science over the past decade. Depending on its driving forces, the process induced in the model protein rHuG-CSF may be either reversible or irreversible, resulting in the assembly of self-associated protein species or irreversible aggregates of various final morphologies. The aim of our work was to investigate the correlation between irreversible and reversible aggregation and the protective effect of non-specific formulation stabilisers, selected from the group of carbohydrates and polyols including trehalose, xylitol, cellobiitol, turanose, cellobiose, leucrose, lactitol, lyxose, and sorbitol, against both irreversible protein aggregation and reversible selfassociation processes of the rHuG-CSF. The formation of irreversible aggregates was thermally induced and evaluated using differential scanning calorimetry and size-exclusion chromatography. As opposed to the irreversible aggregation process, the process of self-association was induced by the agitation experiment by directly augmenting the protein solution contact surfaces. Absence of statistical connectivity between different stabilisers' ability to inhibit self-association or aggregation reactions indicates that these are two distinct physicochemical processes with different formulation stabilizing outcomes.
Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Bein... more Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Beinmyr pegmatite, Norway, using selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The chemical composition of the sample confirmed the affiliation to the samarskite group giving the general formula (. The structure identified by transmission electron microscopy (TEM) techniques is well related to the orthorhombic low-temperature samarskite modification with cell parameters a ¼ 5.68(1), b ¼ 4.94(1), c ¼ 5.24(2) Å . The observed diffraction maxima conform well to Pbcn space group. The untreated sample is X-ray amorphous. Gradual recrystallisation in air from 400 to 1000 C yielded a pyrochlore phase being stable at all experimental temperatures. At 800 C a high-temperature samarskite phase (s.g. P2/c) co-crystallised, with an increase in crystallinity at 1000 C. Recrystallisation in a reducing atmosphere (Ar/H 2 ) did not yield the high-temperature samarskite phase solely. Unsuccessful recrystallisation of the high-temperature samarskite modification is mainly related to an alteration which shifted the composition of samarskite to pyrochlore, as shown by the occurrence of altered domains in the sample.
We have synthesized Ti-Zr-Ni-and Ti-Hf-Ni-based quasicrystals by the mechanical alloying of eleme... more We have synthesized Ti-Zr-Ni-and Ti-Hf-Ni-based quasicrystals by the mechanical alloying of elementary powders with an average particle size of 35 m in a high-energy planetary ball mill followed by a vacuum heat treatment. The X-ray diffraction (XRD) spectra indicate that the mixture was to a large extent amorphous after mechanically alloying for more than 40 h. These largely amorphous precursors, after various times of mechanical alloying, were subsequently analysed by means of differential scanning calorimetry (DSC) in order to obtain the kinetic parameters of crystallization, such as the temperature and the activation energy. DSC was used in combination with XRD to identify the structural changes related to the peaks in the DSC scans. The morphologies and compositions were analysed using scanning electron microscopy with an energy-dispersive spectrometer. We observed agglomerates ranging in size from 5 to 50 m; these agglomerates consisted of smaller particles with sub-micrometer diameters. The composition of the agglomerates was not homogenous, since small areas (∼1 m) of Zr-rich secondary phase were observed inside them. Using a vibrating-sample magnetometer (VSM) we found that the saturation magnetization decreases with mechanical treatment, and is additionally decreased with the time and temperature of a subsequent vacuum heat treatment. The saturation magnetization (M s ) decreases fairly linearly, from the initial mixture of crystalline elements, which is ferromagnetic due to nickel, through to a largely amorphous phase, and then to the quasicrystalline phase, where the M s value is the lowest. As a result, measuring the magnetic properties allows us to probe the structural transformations in the material.
Metamict minerals are characterized by an amorphization of their crystal structure due to radiati... more Metamict minerals are characterized by an amorphization of their crystal structure due to radiation damage, and they present an interesting challenge to the mineral and material scientist. The mechanisms of the crystal structure's metamictization and thermally induced recrystallization have been found not only to be of interest for solving mineralogical and geological problems, but also for helping with practical problems, like nuclear-waste storage. This paper gives an overview of the common problems and some analytical solutions involved in obtaining information about the crystal structure of metamict minerals.
Novel mercury(II) compounds of 3-hydroxypicolinic acid (HpicOH; IUPAC name: 3-hydroxy-2-pyridinec... more Novel mercury(II) compounds of 3-hydroxypicolinic acid (HpicOH; IUPAC name: 3-hydroxy-2-pyridinecarboxylic acid) were synthesized and characterized. HgCl(picOH) (1) and HgBr 2 (HpicOH) (2) were obtained as reaction products from the reaction of the corresponding mercury(II) halide with HpicOH, irrespective of the molar ratio of the reactants. From the reaction of HpicOH and mercury(II) acetate, Hg(picOH) 2 (3) was obtained, while mercury(II) nitrate monohydrate gave the 1/1 solvate with water Hg(picO-H) 2 AE H 2 O (3a). Infrared, 1 H and 13 C NMR spectroscopic data were analyzed for complexes 1, 2 and 3. X-ray crystal structure analysis of 1 and 2 revealed their polymeric nature and different coordination modes of HpicOH. In 1 the deprotonated picolinic acid is N,Ochelating and bridging, while in 2 HpicOH is a O-monodentate weakly bound ligand. Compound 1 consists of HgCl(picOH) moieties with two linear covalent bonds, Hg-N 2.143(4) and Hg-Cl 2.298(1) Å , and four additional HgÁ Á ÁO contacts (2.460(3)-2.904(3) Å ) in which both oxygen atoms from the carboxylic group are bridging and involved in coordination to three neighboring mercury atoms, thus forming infinite layers. The coordination of mercury is 2 + 4. 2 consists of {HgBr 2 (HpicOH)} moieties, which are linked into chains by means of mercury to bromine secondary long range interactions. The coordination sphere of mercury can be described as irregular 2 + 3 formed by two covalently bonded bromine atoms (Hg-Br 2.277(1) and 2.366(1) Å ), two bridging bromine atoms (HgÁ Á ÁBr 3.309(1) and 3.247(1) Å ) and by the HpicOH ligand attached to mercury in the zwitterionic form via the carboxylic oxygen atom (HgÁ Á ÁO 2.602(7) Å ).
The metamict state and recrystallization of fergusonite in metamict natural samples were studied ... more The metamict state and recrystallization of fergusonite in metamict natural samples were studied by thermal methods (TGA-DTA), X-ray powder diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and electron microprobe (EPMA). Two metamict mineral samples of fergusonite were investigated in order to identify the original premetamict crystal structure and to identify recrystallization mechanisms. The TEM data and RS provided evidence on the partial preservation of the original structure in the investigated minerals, which are X-ray amorphous. It was shown that fergusonite could recrystallize from a metamict mineral with original fergusonite structure or from metamictized pyrochlore, which was altered before or after metamictization. Two recrystallization mechanisms were recognized: (a) epitaxial growth occurring at the boundary between preserved premetamict structure fragments and completely metamictized areas, and (b) nucleation-crystal growth mechanism occurring in completely amorphous areas of the minerals, and resulting in recrystallization of the original mineral as well as in the crystallization of a new mineral with a modified chemical composition as compared to the initial matrix.
ABSTRACT Data on the dehydration of pentahydroborite, CaB2O(OH)6·2H2O and nifontovite, Ca3B6O6(OH... more ABSTRACT Data on the dehydration of pentahydroborite, CaB2O(OH)6·2H2O and nifontovite, Ca3B6O6(OH)12·2H2O from the Fuka mine, Japan are presented. Critical temperatures of the dehydration of the borates were determined by thermogravimetric analysis/differential thermal analysis measurements. The untreated mineral samples and their heating products were investigated by X-ray diffraction and Raman spectroscopy. Upon dehydration, both minerals decompose and undergo amorphization, and at greater temperatures crystallize as an orthorhombic calcium borate, CaB2O4 (Pnca). The dehydration paths of the two minerals are different, with nifontovite showing a greater resistance to decomposition and amorphization than pentahydroborite. Differences in the dehydration processes are related to the residuals of the water content and structural accommodation of the borate polyanion.
Cobalt(II) complexes of 6-hydroxypicolinic acid (6-OHpicH), namely [Co(6-OHpic) 2 (H 2 O) 2 ] (1)... more Cobalt(II) complexes of 6-hydroxypicolinic acid (6-OHpicH), namely [Co(6-OHpic) 2 (H 2 O) 2 ] (1) and [Co(6-OHpic) 2 (4-pic) 2 ]AE4-pic (2), and of 2-hydroxynicotinic acid (2-OHnicH), [Co(2-OHnic) 2 (H 2 O) 2 ] (3) were prepared. The crystal structures of free 6-hydroxypicolinic acid monohydrate 6-OHpicHAEH 2 O (4), and the novel polymorph of 2-hydroxynicotinic acid 2-OHnicH (5) and complex 2 were determined by X-ray crystal structure analysis. All compounds were characterized by IR-spectroscopy and thermal methods (TGA/DSC) and data are in agreement with the structure analysis. It was established that 4 and 5 exist in solid state in keto tautomeric form. For 2, structure analysis revealed N,O-chelating mode of 6-hydroxypicolinic acid.
European Journal of Pharmaceutics and Biopharmaceutics, 2010
Severe immunogenic and other debilitating human disorders potentially induced by protein aggregat... more Severe immunogenic and other debilitating human disorders potentially induced by protein aggregates have brought this phenomenon into the focus of biopharmaceutical science over the past decade. Depending on its driving forces, the process induced in the model protein rHuG-CSF may be either reversible or irreversible, resulting in the assembly of self-associated protein species or irreversible aggregates of various final morphologies. The aim of our work was to investigate the correlation between irreversible and reversible aggregation and the protective effect of non-specific formulation stabilisers, selected from the group of carbohydrates and polyols including trehalose, xylitol, cellobiitol, turanose, cellobiose, leucrose, lactitol, lyxose, and sorbitol, against both irreversible protein aggregation and reversible selfassociation processes of the rHuG-CSF. The formation of irreversible aggregates was thermally induced and evaluated using differential scanning calorimetry and size-exclusion chromatography. As opposed to the irreversible aggregation process, the process of self-association was induced by the agitation experiment by directly augmenting the protein solution contact surfaces. Absence of statistical connectivity between different stabilisers' ability to inhibit self-association or aggregation reactions indicates that these are two distinct physicochemical processes with different formulation stabilizing outcomes.
Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Bein... more Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Beinmyr pegmatite, Norway, using selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The chemical composition of the sample confirmed the affiliation to the samarskite group giving the general formula (. The structure identified by transmission electron microscopy (TEM) techniques is well related to the orthorhombic low-temperature samarskite modification with cell parameters a ¼ 5.68(1), b ¼ 4.94(1), c ¼ 5.24(2) Å . The observed diffraction maxima conform well to Pbcn space group. The untreated sample is X-ray amorphous. Gradual recrystallisation in air from 400 to 1000 C yielded a pyrochlore phase being stable at all experimental temperatures. At 800 C a high-temperature samarskite phase (s.g. P2/c) co-crystallised, with an increase in crystallinity at 1000 C. Recrystallisation in a reducing atmosphere (Ar/H 2 ) did not yield the high-temperature samarskite phase solely. Unsuccessful recrystallisation of the high-temperature samarskite modification is mainly related to an alteration which shifted the composition of samarskite to pyrochlore, as shown by the occurrence of altered domains in the sample.
Pseudopolymorphism TGA/DTA methods a b s t r a c t Nickel(II) complexes of 6-bromopicolinic acid,... more Pseudopolymorphism TGA/DTA methods a b s t r a c t Nickel(II) complexes of 6-bromopicolinic acid, namely [Ni(6-Brpic) 2 (H 2 O) 2 ]Á3H 2 O (1) and [Ni(6-Brpic) 2 (H 2 O) 2 ]ÁH 2 O (2) were prepared and characterized by spectroscopic methods (IR), their molecular and crystal structures were determined by X-ray crystal structure analysis and their thermal stability by TGA/DTA methods. Compound 1 was prepared by reaction of nickel(II) nitrate and 6-bromopicolinic acid in aqueous solution at pH value of 8, while 2 was obtained by spontaneous recrystallization of 1 in its mother liquor during few months. These complexes are an example of pseudopolymorphs which differ in number of co-crystallized water molecules but both crystallize in the same crystal system (triclinic). X-ray structural analysis revealed octahedron as a coordination polyhedron in both 1 and 2 and the same N,O-chelated coordination mode of 6-bromopicolinic acid. The coordination sphere of nickel(II) ion is completed by two coordinated water molecules. These pseudopolymorphs differ in their crystal structures which are dominated by intermolecular O-HÁ Á ÁO hydrogen bonds and p-p stacking interactions in both cases. The infrared spectra of 1 and 2 are very similar so these pseudopolymorphs cannot be unambiguously distinguished by IR spectroscopy. Thermal methods confirm number of co-crystallized water molecules in both pseudopolymorphs.
Severe immunogenic and other debilitating human disorders potentially induced by protein aggregat... more Severe immunogenic and other debilitating human disorders potentially induced by protein aggregates have brought this phenomenon into the focus of biopharmaceutical science over the past decade. Depending on its driving forces, the process induced in the model protein rHuG-CSF may be either reversible or irreversible, resulting in the assembly of self-associated protein species or irreversible aggregates of various final morphologies. The aim of our work was to investigate the correlation between irreversible and reversible aggregation and the protective effect of non-specific formulation stabilisers, selected from the group of carbohydrates and polyols including trehalose, xylitol, cellobiitol, turanose, cellobiose, leucrose, lactitol, lyxose, and sorbitol, against both irreversible protein aggregation and reversible selfassociation processes of the rHuG-CSF. The formation of irreversible aggregates was thermally induced and evaluated using differential scanning calorimetry and size-exclusion chromatography. As opposed to the irreversible aggregation process, the process of self-association was induced by the agitation experiment by directly augmenting the protein solution contact surfaces. Absence of statistical connectivity between different stabilisers' ability to inhibit self-association or aggregation reactions indicates that these are two distinct physicochemical processes with different formulation stabilizing outcomes.
Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Bein... more Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Beinmyr pegmatite, Norway, using selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The chemical composition of the sample confirmed the affiliation to the samarskite group giving the general formula (. The structure identified by transmission electron microscopy (TEM) techniques is well related to the orthorhombic low-temperature samarskite modification with cell parameters a ¼ 5.68(1), b ¼ 4.94(1), c ¼ 5.24(2) Å . The observed diffraction maxima conform well to Pbcn space group. The untreated sample is X-ray amorphous. Gradual recrystallisation in air from 400 to 1000 C yielded a pyrochlore phase being stable at all experimental temperatures. At 800 C a high-temperature samarskite phase (s.g. P2/c) co-crystallised, with an increase in crystallinity at 1000 C. Recrystallisation in a reducing atmosphere (Ar/H 2 ) did not yield the high-temperature samarskite phase solely. Unsuccessful recrystallisation of the high-temperature samarskite modification is mainly related to an alteration which shifted the composition of samarskite to pyrochlore, as shown by the occurrence of altered domains in the sample.
We have synthesized Ti-Zr-Ni-and Ti-Hf-Ni-based quasicrystals by the mechanical alloying of eleme... more We have synthesized Ti-Zr-Ni-and Ti-Hf-Ni-based quasicrystals by the mechanical alloying of elementary powders with an average particle size of 35 m in a high-energy planetary ball mill followed by a vacuum heat treatment. The X-ray diffraction (XRD) spectra indicate that the mixture was to a large extent amorphous after mechanically alloying for more than 40 h. These largely amorphous precursors, after various times of mechanical alloying, were subsequently analysed by means of differential scanning calorimetry (DSC) in order to obtain the kinetic parameters of crystallization, such as the temperature and the activation energy. DSC was used in combination with XRD to identify the structural changes related to the peaks in the DSC scans. The morphologies and compositions were analysed using scanning electron microscopy with an energy-dispersive spectrometer. We observed agglomerates ranging in size from 5 to 50 m; these agglomerates consisted of smaller particles with sub-micrometer diameters. The composition of the agglomerates was not homogenous, since small areas (∼1 m) of Zr-rich secondary phase were observed inside them. Using a vibrating-sample magnetometer (VSM) we found that the saturation magnetization decreases with mechanical treatment, and is additionally decreased with the time and temperature of a subsequent vacuum heat treatment. The saturation magnetization (M s ) decreases fairly linearly, from the initial mixture of crystalline elements, which is ferromagnetic due to nickel, through to a largely amorphous phase, and then to the quasicrystalline phase, where the M s value is the lowest. As a result, measuring the magnetic properties allows us to probe the structural transformations in the material.
Metamict minerals are characterized by an amorphization of their crystal structure due to radiati... more Metamict minerals are characterized by an amorphization of their crystal structure due to radiation damage, and they present an interesting challenge to the mineral and material scientist. The mechanisms of the crystal structure's metamictization and thermally induced recrystallization have been found not only to be of interest for solving mineralogical and geological problems, but also for helping with practical problems, like nuclear-waste storage. This paper gives an overview of the common problems and some analytical solutions involved in obtaining information about the crystal structure of metamict minerals.
Novel mercury(II) compounds of 3-hydroxypicolinic acid (HpicOH; IUPAC name: 3-hydroxy-2-pyridinec... more Novel mercury(II) compounds of 3-hydroxypicolinic acid (HpicOH; IUPAC name: 3-hydroxy-2-pyridinecarboxylic acid) were synthesized and characterized. HgCl(picOH) (1) and HgBr 2 (HpicOH) (2) were obtained as reaction products from the reaction of the corresponding mercury(II) halide with HpicOH, irrespective of the molar ratio of the reactants. From the reaction of HpicOH and mercury(II) acetate, Hg(picOH) 2 (3) was obtained, while mercury(II) nitrate monohydrate gave the 1/1 solvate with water Hg(picO-H) 2 AE H 2 O (3a). Infrared, 1 H and 13 C NMR spectroscopic data were analyzed for complexes 1, 2 and 3. X-ray crystal structure analysis of 1 and 2 revealed their polymeric nature and different coordination modes of HpicOH. In 1 the deprotonated picolinic acid is N,Ochelating and bridging, while in 2 HpicOH is a O-monodentate weakly bound ligand. Compound 1 consists of HgCl(picOH) moieties with two linear covalent bonds, Hg-N 2.143(4) and Hg-Cl 2.298(1) Å , and four additional HgÁ Á ÁO contacts (2.460(3)-2.904(3) Å ) in which both oxygen atoms from the carboxylic group are bridging and involved in coordination to three neighboring mercury atoms, thus forming infinite layers. The coordination of mercury is 2 + 4. 2 consists of {HgBr 2 (HpicOH)} moieties, which are linked into chains by means of mercury to bromine secondary long range interactions. The coordination sphere of mercury can be described as irregular 2 + 3 formed by two covalently bonded bromine atoms (Hg-Br 2.277(1) and 2.366(1) Å ), two bridging bromine atoms (HgÁ Á ÁBr 3.309(1) and 3.247(1) Å ) and by the HpicOH ligand attached to mercury in the zwitterionic form via the carboxylic oxygen atom (HgÁ Á ÁO 2.602(7) Å ).
The metamict state and recrystallization of fergusonite in metamict natural samples were studied ... more The metamict state and recrystallization of fergusonite in metamict natural samples were studied by thermal methods (TGA-DTA), X-ray powder diffraction (XRD), Raman spectroscopy (RS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and electron microprobe (EPMA). Two metamict mineral samples of fergusonite were investigated in order to identify the original premetamict crystal structure and to identify recrystallization mechanisms. The TEM data and RS provided evidence on the partial preservation of the original structure in the investigated minerals, which are X-ray amorphous. It was shown that fergusonite could recrystallize from a metamict mineral with original fergusonite structure or from metamictized pyrochlore, which was altered before or after metamictization. Two recrystallization mechanisms were recognized: (a) epitaxial growth occurring at the boundary between preserved premetamict structure fragments and completely metamictized areas, and (b) nucleation-crystal growth mechanism occurring in completely amorphous areas of the minerals, and resulting in recrystallization of the original mineral as well as in the crystallization of a new mineral with a modified chemical composition as compared to the initial matrix.
ABSTRACT Data on the dehydration of pentahydroborite, CaB2O(OH)6·2H2O and nifontovite, Ca3B6O6(OH... more ABSTRACT Data on the dehydration of pentahydroborite, CaB2O(OH)6·2H2O and nifontovite, Ca3B6O6(OH)12·2H2O from the Fuka mine, Japan are presented. Critical temperatures of the dehydration of the borates were determined by thermogravimetric analysis/differential thermal analysis measurements. The untreated mineral samples and their heating products were investigated by X-ray diffraction and Raman spectroscopy. Upon dehydration, both minerals decompose and undergo amorphization, and at greater temperatures crystallize as an orthorhombic calcium borate, CaB2O4 (Pnca). The dehydration paths of the two minerals are different, with nifontovite showing a greater resistance to decomposition and amorphization than pentahydroborite. Differences in the dehydration processes are related to the residuals of the water content and structural accommodation of the borate polyanion.
Cobalt(II) complexes of 6-hydroxypicolinic acid (6-OHpicH), namely [Co(6-OHpic) 2 (H 2 O) 2 ] (1)... more Cobalt(II) complexes of 6-hydroxypicolinic acid (6-OHpicH), namely [Co(6-OHpic) 2 (H 2 O) 2 ] (1) and [Co(6-OHpic) 2 (4-pic) 2 ]AE4-pic (2), and of 2-hydroxynicotinic acid (2-OHnicH), [Co(2-OHnic) 2 (H 2 O) 2 ] (3) were prepared. The crystal structures of free 6-hydroxypicolinic acid monohydrate 6-OHpicHAEH 2 O (4), and the novel polymorph of 2-hydroxynicotinic acid 2-OHnicH (5) and complex 2 were determined by X-ray crystal structure analysis. All compounds were characterized by IR-spectroscopy and thermal methods (TGA/DSC) and data are in agreement with the structure analysis. It was established that 4 and 5 exist in solid state in keto tautomeric form. For 2, structure analysis revealed N,O-chelating mode of 6-hydroxypicolinic acid.
European Journal of Pharmaceutics and Biopharmaceutics, 2010
Severe immunogenic and other debilitating human disorders potentially induced by protein aggregat... more Severe immunogenic and other debilitating human disorders potentially induced by protein aggregates have brought this phenomenon into the focus of biopharmaceutical science over the past decade. Depending on its driving forces, the process induced in the model protein rHuG-CSF may be either reversible or irreversible, resulting in the assembly of self-associated protein species or irreversible aggregates of various final morphologies. The aim of our work was to investigate the correlation between irreversible and reversible aggregation and the protective effect of non-specific formulation stabilisers, selected from the group of carbohydrates and polyols including trehalose, xylitol, cellobiitol, turanose, cellobiose, leucrose, lactitol, lyxose, and sorbitol, against both irreversible protein aggregation and reversible selfassociation processes of the rHuG-CSF. The formation of irreversible aggregates was thermally induced and evaluated using differential scanning calorimetry and size-exclusion chromatography. As opposed to the irreversible aggregation process, the process of self-association was induced by the agitation experiment by directly augmenting the protein solution contact surfaces. Absence of statistical connectivity between different stabilisers' ability to inhibit self-association or aggregation reactions indicates that these are two distinct physicochemical processes with different formulation stabilizing outcomes.
Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Bein... more Relics of the original samarskite structure were identified in a metamict ABO 4 mineral from Beinmyr pegmatite, Norway, using selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The chemical composition of the sample confirmed the affiliation to the samarskite group giving the general formula (. The structure identified by transmission electron microscopy (TEM) techniques is well related to the orthorhombic low-temperature samarskite modification with cell parameters a ¼ 5.68(1), b ¼ 4.94(1), c ¼ 5.24(2) Å . The observed diffraction maxima conform well to Pbcn space group. The untreated sample is X-ray amorphous. Gradual recrystallisation in air from 400 to 1000 C yielded a pyrochlore phase being stable at all experimental temperatures. At 800 C a high-temperature samarskite phase (s.g. P2/c) co-crystallised, with an increase in crystallinity at 1000 C. Recrystallisation in a reducing atmosphere (Ar/H 2 ) did not yield the high-temperature samarskite phase solely. Unsuccessful recrystallisation of the high-temperature samarskite modification is mainly related to an alteration which shifted the composition of samarskite to pyrochlore, as shown by the occurrence of altered domains in the sample.
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Papers by Masa Linaric