Добірка наукової літератури з теми "C-P Bond Formation"

This review is a comprehensive account of reactions with the participation of nickel complexes that result in the formation of carbon–phosphorus (C‒P) bonds. The catalytic and non-catalytic reactions with the participation of nickel complexes as the catalysts and the reagents are described. The various classes of starting compounds and the products formed are discussed individually. The several putative mechanisms of the nickel catalysed reactions are also included, thereby providing insights into both the synthetic and the mechanistic aspects of this phosphorus chemistry.

AbstractThe development of practical, efficient and atom-economical methods of formation of carbon-phosphorus bonds remains a topic of considerable interest for the current synthetic organic chemistry and electrochemistry. This review summarizes selected topics from the recent publications with particular emphasis on phosphine and phosphine oxides formation from white phosphorus, chlorophosphines in electrocatalytic processes using aryl, hetaryl or perfluoroalkyl halides as reagents. This review includes selected highlights concerning recent progress in modification of catalytic systems for aromatic C–H bonds phosphonation involving metal-catalyzed ligand directed or metal-induced oxidative processes. Furthermore, a part of this review is devoted to phosphorylation of olefins with white phosphorus under reductive conditions in water-organic media. Finally, we have also documented recent advances in ferrocene C–H activation and phosphorylation.

Phosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C–P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C–P bond.

This thesis describes the catalysed addition of X-H bonds (X = S, O and N) to alkynes using a range of novel rhodium(I) and iridium(I) complexes containing hybrid bidentate phosphine-pyrazolyl, phosphine-imidazolyl and phosphine-N heterocyclic carbene (NHC) donor ligands. The synthesis of novel bidentate phosphine-pyrazolyl, phosphine-imidazolyl (P-N) and phosphine-NHC (PC) donor ligands and their cationic and neutral rhodium(I) and iridium(I) complexes [M(P N)(COD)]BPh4, [M(PC)(COD)]BPh4, [Ir(P-N)(CO)2]BPh4 and [M(P-N)(CO)Cl] were successfully performed. An unusual five coordinate iridium complex with phosphine-NHC ligands [Ir(PC)(COD)(CO)]BPh4 was also obtained. Seventeen single crystal X-ray structures of these new complexes were determined. A range of these novel rhodium and iridium complexes were effective as catalysts for the addition of thiophenol to a variety of alkynes. Iridium complexes were more effective than rhodium analogues. Cationic complexes were more effective than neutral complexes. Complexes with hybrid phosphine-nitrogen donor were more effective than complexes containing bidentate nitrogen donor ligands. An atom-economical, efficient method for the synthesis of cyclic acetals and bicyclic O,O-acetals was successfully developed based on the catalysed hydroalkoxylation. Readily prepared terminal and non-terminal alkyne diols were cyclised into bicyclic O,O-acetals in quantitative conversions in most cases. The efficiency of a range of rhodium and iridium complexes containing bidentate P-N and PC donor ligands as catalysts for the cyclisation of 4-pentyn-1-amine to 2-methyl-1-pyrroline varied significantly. The cationic iridium complexes with the bidentate phosphine-pyrazolyl ligands, [Ir(R2PyP)(COD)]BPh4 (2.39-2.42) were extremely efficient as catalysts for this transformation. Increasing the size of the substituent on or adjacent to the donor led to improvement in catalytic activity of the corresponding metal complexes. The mechanism of the catalysed hydroalkoxylation was proposed to proceed by the initial activation of the alkyne via ?? coordination to the metal centre. The ?? binding of both aliphatic and aromatic alkynes to [Ir(PyP)(CO)2]BPh4 (2.44) was observed by low temperature NMR and no reaction between 2.44 and alcohols was observed. In contrast, the facility in which thiol and amine oxidatively added to 2.44 led the proposal that in the hydrothiolation and hydroamination reaction, the catalytic cycle commences with the activation of the X-H bond (X = S, N) by an oxidative addition process.

Au cours de ce travail de nouvelles méthodes pour la formation de liaison C-N ont été développées. Dans la première partie de cette thèse une application de catalyse métal-ligand bifonctionnelle pour la réaction énantiosélective aza-Michael est démontrée. Dans la deuxième partie nous présentons le travail sur les cyclisations, en utilisant des alcaloïdes du quinquina facilement disponibles, comme catalyseurs des plus prometteurs, fournissant des β-amino-acides d’indoline avec jusqu'à 98% ee. Parmi eux, l’hydroquinidine ressort du lot comme étant le catalyseur donnant le meilleur excès énatiomérique. La troisième partie est liée à l'élaboration d'un nouveau processus intermoléculaires de diamination de styrènes, diènes et triènes, utilisant des bis-sulfonylimides comme source d'azote, en combinaison avec le diacétate de iodosobenzène, qui fournit une approche intéressante et efficace de diamines vicinales biologiquement et chimiquement important. La réaction peut être effectuée à température ambiante sans avoir besoin de protection par atmosphère inerte
The concept of metal-ligand bifunctionality was successfully applied for an enantioselective aza-Michael reaction by employing well-defined ruthenium amido complexes. The catalyst was optimised and the corresponding chiral indoline β-amino acid derivatives were obtained with high enantioselectivities. Next, a straightforward enantioselective bifunctional organocatalytic approach was also developed. Employing hydroquinidine as catalyst the corresponding cyclic products were obtained in excellent enantioselectivities and quantitative yields. These compounds can be selectively deprotected and applied to peptide synthesis. Finally, we have developed unprecedented diamination reactions of styrenes, butadienes and hexatrienes employing easily accessible hypervalent iodine(III) reagents under robust reaction conditions. The first examples of the metal-free 1,2-diamination of butadienes were demonstrated and this oxidation methodology was further extended to the highly attractive 1,4 installation of two nitrogen atoms within a single step

博士
國立中正大學
化學所
93
Abstract This thesis involves the synthesis, characterization of a new class of aza-based bidentate phosphinic amide ligands, the study of catalytic applicability of the phosphinic amido palladium complexes to various Heck-type C-C formation reactions, and the kinetic and theoratic study of organotungsten Lweis acid catalyzed Diels-Alder reactions. The thesis also includes discussions of a new path for P-C cleavage which is induced by the basicity of the reaction system. The results and discussion will be categorized into four independent chapters. In the first chapter, we mainly focused our research efforts on the syntheses, structural characterization of a series of gold nanosurface-immobilized palladium(II) complex catalysts, and their catalytic reactivity towards various Heck-type C-C coupling reactions. Spherical gold nanoparticles of a diameter of 2.7 ± 0.5 nm in size were used as support for molecular palladium complex catalysts. These gold nanoparticles were obtained by the chemical reduction method using NaBH4 as the reducing agent to reduce HAuCl4・3H2O in the presence of CH3(CH2)7SH stabilizer. The compound [HS(CH2)11N(H)(O)P(2-py)2] (4), which was derived from Br(CH2)11OH, with both ends having coordination capability was specially designed as the linker between molecular metal catalysts and metal nanosurfaces. The thiol end (HS) of the anchoring linker can be put onto gold nanoparticles’ surfaces by ligand exchange at elevated temperature. Four types of “soluble” or “dispersible” gold nanoparticle-supported ligands, Au−L-A~D (Au−L = Au−S(CH2)11N(H)P(O)(2-py)2), anchored with different amounts of spacing linkers with diameters of 3-5 nm in size were synthesized by design. Again, these gold nanoparticle-supported ligands can be dispersed (or dissolved) in various organic solvents, such as CH3Cl, DMSO, MeOH, EtOH and CH3CN, etc. The direct reaction of the above-mentioned four types of ligands, Au−L-A~D, with palladium (II) complex, Pd(CH3CN)2Cl2, resulted in the formation of “soluble” gold nanosurface-immobilized palladium complexes, Au−L−Pd-A~D (Au−L−Pd = Au−S(CH2)11N(H)P(O)(2-py)2PdCl2). The diameters of the gold cores remain unchanged after palladation, and these gold nanoparticles dissolve in DMSO and MeOH fairly easily. Taking the advantage of the high solubility, A rapid and precise method to structurally characterize these systems (Au−L−Pd-A~D) using solution 1H, 13C and 31P probe NMR spectroscopy becomes accessible. In addition to the NMR technique, the atomic absorption spectroscopy (AA) was also used to determine the amount of Pd catalysts anchored on gold nanoparticle’s surface. By performing a size-and-particle calculation based on the TEM image, one can obtain the average number of Pd catalysts and stabilizers on each gold nanoparticle’s surface. These gold nanoparticle-supported palladium complexes, Au−L−Pd-A~D, were demonstrated to be highly effective catalysts for various Heck C-C coupling reactions. The turnnover frequencies (TOF) of 35000-45000 h-1 were obtained for the A-D systems. The controlled experiment of the molecular palladium complex catalyst HO(CH2)11N(H)(O)P(2-py)2PdCl2) (6) promoted Heck reactions gave TOF values of 10,000-17,000 h-1, which are 3~4 times less than those obtained for the Au−L−Pd-A~D catalytic systems. The kinetic studies revealed that a second order kinetic behavior was found for all the homogeneous 6-catalyzed Heck C-C coupling reactions. However, the kinetic studies showed that the gold nanoparticle-supported catalytic systems deviated dramatically from a normal second order kinetic behavior. In the second chapter, A new class of bidentate, aza-based phosphinic amide ligands, RNHP(O)(2-py)2, where R = CH2CH(CH2)9, HOCH2(CH2)10, (O)3Si(CH2)11, was efficiently synthesized via a one-pot Staudinger reaction of organic azides and 2-pyridylphosphines followed by in situ hydrolyses. The complex CH2CH(CH2)9NHP(O)(2-py)2 was structurally characterized, and its ORTEP drawing showed a pentavalent, trigonal pyramidal arrangement around the P center. The intermediate iminophosphoranes, CH2CH(CH2)9N=P(2-py)3, CH2CH(CH2)9N=P(Ph)- (2-py)2, CH2CH(CH2)9N=P(Ph)2(2-py) and CH2CH(CH2)9N=PPh3 were isolated by design and their hydrolyses in both acidic and basic environments were carefully studied. While all four compounds followed the expected route of a P=N cleavage to give CH2CH(CH2)9NH3+ and phosphine oxides in acidic environments. Hydrolyses of the iminopyridlphosphoranes CH2CH(CH2)9N=P(Ph)n(2-py)2-n (n = 0, 1, 2) under basic conditions produced an N-substituted phosphinic amide, CH2CH(CH2)9NHP(O)(Ph)n(2-py)2-n and a free pyridine via a P-C cleavage. The pyridylphosphorane with e-donating OMe-substituent, CH2CH(CH2)9N=PPh(2-py-4-OMe)2, hydrolyzed in a much slower rate as compared to its parent pyridylphosphoranes. On the contrary, the phenylphosphoranes with e-withdrawing halide-substituents, CH2CH(CH2)9N=P(4-X-Ph)3 (X = F, Cl), hydrolyzed in a noticeably faster rate with reference to their nonsubstituted counterpart. Three different palladium catalysts with a stable metallahexacycle formed around the Pd center were synthesized by the complexation of phosphinic amide ligand with Pd(CH3CN)2Cl2. The soluble, molecular HOCH2(CH2)10NHP(O)(2-py)2PdCl2 catalyzed Heck-type reactions of iodobenzene and acrylates and/or styrene very efficiently to give TOF values of 10,000-17,000 h-1. Both SiO2-supported homogeneous and heterogeneous, (O)3Si−(CH2)11NHP(O)(2-py)2PdCl2, are effective and regioselective catalysts for [2+2+2] alkyne cyclotrimerization reactions and can be successfully reused up to the sixth cycle without the problem of losing activity. In the third chapter, the based-catalyzed hydrolysis of two different phosphine oxides O=PX3 (X = 2-pyridy, phenyl) were carefully studied. The mixed phenyl/pyridyl phosphine oxides O=PPhn(2-py-X)3-n, where X = H, n= 1, 2； X= Me, OMe, n = 1, were hydrolyzed in the presence of base to give [HO(O)PPhn(2-py-X)2-n] and pyridine as products. The results of kinetic study showed that the rate of hydrolysis would decrease while the number of phenyl group increases as follows: O=P(2-py)3> O=PPh(2-py)2> O=PPh2(2-py). However, the measured reaction barriers for hydrolyses were found to be increased when the H atom at the para-position on the pyridyl group of O=PPh(2-py)2 replaced with the e-donating groups, OMe or Me. The rates of hydrolyses were in the following order: O=PPh(2-py)2> O=PPh(2-py-4-Me)2 > O=PPh(2-py-4-OMe)2. For phenyphosphine oxides O=P(4-Ph-X)3, where X = F and Cl, the hydrolyses can be carried out to give [HO(O)P(Ph-X)2-n] and halogenated benzene as products. The hydrolysis rates for this series of phenylphosphine oxides were found in the following order: O=P(Ph-F)3> O=P(Ph-Cl)3> O=PPh3. The parent triphenylphosphine oxide, however, would not undergo hydrolysis even at temperature of 190 oC for days. The energy barriers of the based-catalyzed hydrolysis were calculated by using HF/6-31+G* and B3LYP/6-31+G* level of theory, and the results were consistent with the experimental observation. We found that the energy barriers for the hydrolyses followed the similar trend shown below in its decreasing order: O=P(2-py)3> O=PPh(2-py)2> O=PPh(2-py-4-Me)2 > O=PPh(2-py-4-OMe)2 > O=PPh2(2-py)> O=P(Ph-F)3> O=P(Ph-Cl)3> O=PPh3. In the last chapter, the catalytic reactivity of tungsten Lewis acid [P(2-py)3W(CO)(NO)2]2+ toward Diels-Alder reaction of cyclopentadiene and methyl vinyl kentone and/or 1,3-cyclohexadiene and methyl vinyl kentone were discussed. Comprehensive kinetic measurements of both the uncatalyzed and the corresponding 1-catalyzed Diels-Alder reaction of cyclopentadiene and methyl vinyl kentone as well as cyclohexadiene and methyl vinyl kentone were conducted at various temperatures. Based on the results of these kinetic works, we were able to obtain lavish information to quantify the catalyst efficiencies. For example, the activation energies, preexponetial factors, entropies of the transition state, the reaction rate constants, and reaction order were determined. According to these results, a reasonable mechanism and the reaction rate determining step of the 1-catalyzed Diels-Alder reactions of cyclopentadiene and methyl vinyl kentone as well as cyclohexadiene and methyl vinyl kentone were therefore suggested. The experiment of this chapter is research of continuing the laboratory schoolmate, so does not do the detailed discussion in this thesis, only publish it the thesis and examine and enclose it in the appendix.

碩士
國立中興大學
化學系所
104
Secondary phosphine oxides (SPOs) are air-/moisture-stable and are advantageous for the purpose of storage. They might act as preligands towards transition metals after conversion to its tautomeric form, Phosphinous Acid (PA). Palladium complexes A-C were obtained from the reactions of Pd(II) with some selected secondary phosphine oxides (SPOs) and imines. The same chemical formula of palladium complex C with two different orientations of ligands were determined by single-crystal X-ray diffraction methods. Direct C-H functionalization of benzoquinone (BQ) was observed from the reaction of it with secondary phosphine oxides plus imines and in the presence of oxidant Ag+. Through this method, a variety of benzoquinone derivatives with both C-N and C-P bond formations on BQ were achieved in one-pot reaction and with high yields. The yields of the C-H functionalization of benzoquinone were enhanced by the extra addition of certain amount of Pd(OAc)2. Similar C-H functionalization on naphthoquinone (NQ) was also observed. A mechanism was proposed to account for the formations of all the quinone derivatives. It is believed that the reaction does not undergo a radical reaction pathway, as reported in many related works.

碩士
國立中興大學
化學系所
104
In this work, the synthesis and characterization of several quinone derivatives with specific configurations were described. Stoichiometric amount of silver carbonate was employed and the C-H activation on the quinone was observed. Crystal structures of several newly-made quinone derivatives were determined by X-ray diffraction methods. These novel quinone derivatives having both phosphine group(s) and amine functional group(s) might act as P,N-bidentate ligands toward transition metals and form metal-containing pre-catalysts. The potential of these pre-catalysts in catalysis is worthy of exploring in the future.

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

Turbine inlet temperatures have now approached 1650°C (3000°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching or exceeding 445 kN (100,000 lbs.). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, computerized design technology for stresses and airflow and the development and application of rhenium (Re) containing, high γ′ volume fraction nickel-base single crystal superalloys, with advanced coatings, including prime-reliant ceramic thermal barrier coatings (TBCs). Re additions to cast airfoil superalloys not only improve creep and thermo-mechanical fatigue strength but also environmental properties, including coating performance. Re slows down diffusion in these alloys at high operating temperatures.(1) At high gas temperatures, several issues are critical to turbine engine performance retention, blade life and integrity. These are tip oxidation in particular for shroudless blades, internal oxidation for lightly cooled turbine blades and TBC adherence to both the airfoil and tip seal liner. It is now known that sulfur (S) at levels < 10 ppm but > 0.2 ppm in these alloys reduces the adherence of α alumina protective scales on these materials or their coatings by weakening the Van der Waal’s bond between the scale and the alloy substrate. A team approach has been used to develop an improvement to CMSX-4® alloy which contains 3% Re, by reducing S and phosphorus (P) levels in the alloy to < 2 ppm, combined with residual additions of lanthanum (La) + yttrium (Y) in the range 10–30 ppm. Results from cyclic, burner rig dynamic oxidation testing at 1093°C (2000°F) show thirteen times the number of cycles to initial alumina scale spallation for CMSX-4 [La + Y] compared to standard CMSX-4. A key factor for application acceptance is of course manufacturing cost. The development of improved low reactivity prime coats for the blade shell molds along with a viable, tight dimensional control yttrium oxide core body are discussed. The target is to attain grain yields of single crystal CMSX-4 (ULS) [La + Y] turbine blades and casting cleanliness approaching standard CMSX-4. The low residual levels of La + Y along with a sophisticated homogenisation/solutioning heat treatment procedure result in full solutioning with essentially no residual γ/γ′ eutectic phase, Ni (La, Y) low melting point eutectics and associated incipient melting pores. Thus, full CMSX-4 mechanical properties are attained. The La assists with ppm chemistry control of the Y throughout the single crystal turbine blade castings through the formation of a continuous lanthanum oxide film between the molten and solidifying alloy and the ceramic core and prime coat of the shell mold. Y and La tie up the < 2 ppm but > 0.2 ppm residual S in the alloy as very stable Y and La sulfides and oxysulfides, thus preventing diffusion of the S atoms to the alumina scale layer under high temperature, cyclic oxidising conditions. La also forms a stable phosphide. CMSX-4 (ULS) [La + Y] HP shroudless turbine blades will commence engine testing in May 1998.

Incubation of purified human plasma prekallikrein with sulfatides or dextran sulfate resulted in spontaneous activation of prekallikrein as judged by the appearance of amidolytic activity towards the chromogenic substrate H-D-pro-phe-arg-p-nitroanilide (S 2302). The time course of generation of amidolytic activity was sigmoidal with an apparent lag phase followed by a rapid activation until finally a plateau was reached. Soybean trypsin inhibitor completely blocked prekallikrein activation whereas corn, limabean and ovomucoid trypsin inhibitor did not. The Ki of the reversible inhibitor, benzamidine, for autoactivation (240 uM) was identical to the Ki of benzamidine for kallikrein. Thus, spontaneous prekallikrein activation and kallikrein showed the same specificity for a number of serine protease inhibitors, indicating that prekallikrein is activated by its own enzymatically active form, kallikrein. Immunoblotting analysis showed that, concomitant with the appearance of amidolytic activity, prekallikrein was cleaved. However, prekallikrein was not quantitatively converted into two-chain kallikrein since other polypeptide products were visible on the gels. This accounts for the observation that in amidolytic assays not all prekallikrein present in the reaction mixture was measured as active kallikrein. Kinetic analysis showed that prekallikrein activation can be described by a second-order reaction mechanism in which prekallikrein is activated kallikrein. The apparent second order rate constant was 27000 M-ls-1 (pH 7.2, 50 uM sulfatides, ionic strength 1=0.06, at 37°C). Autocatalytic prekallikrein activation was strongly dependent on the ionic strength, since there was a considerable decrease in the rate of the reaction at high salt concentrations. Our data support a prekallikrein autoactivation mechanism in which surface-bound kallikrein activates surface-bound prekallikrein. The rate constant of autoactivation is considerably lower than the rate constants reported for Factor Xlla dependent prekallikrein formation. Autocatalytic prekallikrein activation may, however, contribute to kallikrein formation during the initiating phase of contact activation.

The material requirements on aircraft engine mainshaft bearings increase due to an elevated speed index (bearing bore diameter multiplied by rotational shaft speed) and slip ratios [1]. The formation of reaction layers on surfaces in mechanical contact is strongly affected by the tribological loading conditions, the materials used, the lubricant, and the service temperature. An appropriate reactivity between material and lubricant in tribological systems decreases wear and friction and increases the durability [2,3]. Goal of the paper is to compare wear and friction properties of standard aerospace bearing steel AMS 6491 (M50) with that of the high strength stainless steel grade AMS 5898. The nominal chemical compositions are 0.82C-4.1Cr-1V-4.2Mo (wt%) and 0.3C-0.4N-15.2Cr-1Mo (wt%), respectively. In order to characterize the material behavior under pure sliding conditions, ball on disc (BOD) experiments were performed with a contact pressure of 1GPa and a sliding speed of 10 cm/s at room temperature and at 150°C. As lubricant the jet engine oil Mobil Jet II was used. It is assumed that the reaction layer formation depends on the material composition and is also effected by the counterpart and the lubricant additives. Thus, the experiments were performed with two different ball materials. The first ball material was the same standard aerospace bearing steel (M50) as mentioned above and the second was a ceramic (Si3N4). The homogeneity and the distribution of the reaction layers as well as the wear rate were determined in the contact zone by means of optical profilometry, scanning electron microscopy (SEM) and Fourier transformation infrared spectroscopy (FTIR). The study showed that wear is significantly higher on the stainless steel grade compared to M50 (Fig. 1a and Fig. 1b). The dark areas in Fig. 2 are phosphorus rich regions on the wear track of M50. This reaction layer is mainly built up of phosphates, which result from the TCP lubricant additive. In the FT-IR spectra (Fig. 3) absorption bands at 1130 cm−1 (room temperature-BOD test) and at 1160 cm−1 (150°C-BOD test) are visible, which result from the P=O stretching [4]. The shift of the absorption band to lower wave numbers with decreasing test temperature is probably due to hydrogen bonding [5]. Contrary to AMS 6491 no measurable reaction layer was found on AMS 5898 after testing at room temperature (Fig. 1b). The friction coefficients of the two steels against Si3N4 balls determined in the BOD tests are compared in Fig. 4. AMS 5898 shows an abrupt increase of the friction coefficient after a sliding distance of 3.5 m. The reason for that is a material transfer of disc material to the ceramic ball as can be seen in Fig. 5. This transfer material causes a plowing of the disc and thus, an increased wear can be observed. The different Cr-contents and consequently oxide layers of AMS 5898 and AMS 6491, which react differently with TCP, might explain this behavior. AMS 5898 does not sufficiently react with TCP at room temperature to form a protective layer. Consequently, material transfer and increased wear occurs. In case of AMS 6491 an increase of the operating temperature cause a change of the reaction layer (see Fig. 3) and to an increase in the wear rate.

Abstract Since easy oil is diminishing, the entire world started to look after unconventional resources to meet international demand of hydrocarbons. Heavy oil resources represent more than 40% of natural resources within our Earth crust; that is why it has a special focus internationally. Gulf of Suez Petroleum Company (GUPCO) is a leading E&P company that produced c. 40% of Egypt's total cumulative oil to date. In spite of that success, GUPCO recovered only c. 2.0 MMSTBO out of c. 500+ MMSTBO of heavy oil resources in Gulf of Suez. Historically, many efforts were spent in order to exploit such huge volume but in vain due to the reservoir harsh-conditions at which most of conventional approaches fail. This paper addresses successful application of Microbial EOR as Huff'n Puff Pilot to recover heavy oil in Gulf of Suez, Egypt. GUPCO heavy oil resources is mainly in Nubia formation, October field (offshore). Nubia is a thick fluvial system high quality deep reservoir (11,250 feet tvdSS) with 290 deg. F. temperature, 190,000 PPM Salinity, 14 deg. API, 600 cP viscosity, 2800 psi average reservoir pressure with inter-bedding tar mats. Such conditions (especially temperature, salinity and depth) are barriers for conventional EOR methods especially in offshore environment, and here it comes the special role of reservoir indigenous microorganisms. Indigenous bacteria can be induced by organic fertilizers to produce biological metabolites that may help in recovering heavy oil. The MEOR Pilot was studied in three phases; Phase-1: Sampling & Microbiological Assessment, Phase-2: Lab Experiments & Fermentation and Phase-3: Execution. A water sample was taken from the heavy oil well, and microbiological assessment concluded presence of five species of indigenous bacteria that can produce biogases, bio-surfactant and biopolymers. Second phase involved fertilizers optimization by addressing optimum P/N ratio, organic/inorganic sources and growth rate in addition to fermentation process in the lab. Several core-flooding tests were conducted to define the prize at core-plug scale. After two years of research, the optimum fertilizer was fermented that resulted in 12% heavy oil recovery for one PV Injected. Third phase was pilot implementation at which 160 barrels of fertilizers were injected into the well. The well was shut-in for soaking for 3 days, and then re-opened. After treatment, the oil API increased from 24 deg. up to 40 deg., oil viscosity from 630 cP down to 390 cP, Asphaltenes content from 14.5% to 9.6% with 412 BOPD gain. By modeling these results, MEOR succeeded to achieve a recovery of 41% of the drainage radius STOOIP that is very promising in flooding applications which is being planned at time being. MEOR was found very efficient in recovering heavy oil in a technically challenging reservoir. Lab experiments and fertilizers optimization are key stages that have many know-hows. In this paper, laboratory experiments will be elaborated, pilot design and execution operational considerations will be presented as well. This paper is a good example of a typical MEOR study workflow that can be followed by E&P companies need to unlock such challenging resources in their portfolio.