The tricarboxylic acid （TCA） cycle is a central route for oxidative phosphorylation in cells, and fulfills their bioenergetic, biosynthetic, and redox balance require- ments. Despite early dogma that cancer cells by...The tricarboxylic acid （TCA） cycle is a central route for oxidative phosphorylation in cells, and fulfills their bioenergetic, biosynthetic, and redox balance require- ments. Despite early dogma that cancer cells bypass the TCA cycle and primarily utilize aerobic glycolysis, emerging evidence demonstrates that certain cancer cells, especially those with deregulated oncogene and tumor suppressor expression, rely heavily on the TCA cycle for energy production and macromolecule synthesis. As the field progresses, the importance of aberrant TCA cycle function in tumorigenesis and the potentials of applying small molecule inhibitors to perturb the enhanced cycle function for cancer treatment start to evolve. In this review, we summarize current knowledge about the fuels feeding the cycle, effects of oncogenes and tumor suppressors on fuel and cycle usage, common genetic alterations and deregulation of cycle enzymes, and potential therapeutic opportunities for targeting the TCA cycle in cancer cells. With the application of advanced technology and in vivo model organism studies, it is our hope that studies of this previously overlooked biochemical hub will provide fresh insights into cancer metabolism and tumorigenesis, subsequently revealing vulnerabilities for thera- peutic interventions in various cancer types.展开更多
AIM: To establish an ultrasonographic classification based on a large sample of patients with confirmed hepatic alveolar echinococcosis(AE).METHODS: Clinical data and ultrasonography(US) findings of 185 patients(100 m...AIM: To establish an ultrasonographic classification based on a large sample of patients with confirmed hepatic alveolar echinococcosis(AE).METHODS: Clinical data and ultrasonography(US) findings of 185 patients(100 males; 85 females; mean age at diagnosis: 51.4 ± 17.6 years; mean age at time of US examination: 58.7 ± 18.2 years) were retrospectively reviewed with respect to the US morphology of hepatic AE lesions. The sonomorphological findings were grouped according to a five-part classification scheme.RESULTS: Application of the new classification resulted in the following distribution of sonomorphological patterns among the patients examined: hailstorm(54.1%); pseudocystic(13.5%); ossification(13.0%); hemangioma-like(8.1%); and metastasis-like(6.5%). Only 4.9% of lesions could not be assigned to a sonomorphological pattern.CONCLUSION: The sonomorphological classification proposed in the present study facilitates the diagnosis,interpretation and comparison of hepatic alveolar echinococcosis in routine practice and in the context of scientific studies.展开更多
AIM:Cydooxygenases (COX) are key enzymes for conversion of arachidonic acid to prostaglandins.Nitric oxide synthase (NOS) is the enzyme responsible for formation of nitric oxide. Both have constitutive and inducible i...AIM:Cydooxygenases (COX) are key enzymes for conversion of arachidonic acid to prostaglandins.Nitric oxide synthase (NOS) is the enzyme responsible for formation of nitric oxide. Both have constitutive and inducible isoforms.The inducible isoforms (iNOS and COX-2) are of great interest as regulators of tumor angiogenesis,tumorigenesis and inflammatory processes.This study was to clarify their role in pancreatic adenocarcinomas. METHODS:We investigated the immunohistochemical iNOS and COX-2 expression in 40 pancreatic ductal adenocardnomas of different grade and stage.The results were compared with microvessel density and dinicopathological data. RESULTS:Twenty-one (52.5%) of the cases showed iNOS expression,15 (37.5%) of the cases were positive for COX-2. The immunoreaction was heterogeneously distributed within the tumors.Staining intensity was different between the tumors.No correlation between iNOS and COX-2 expression was seen.There was no relationship with microvessel density. However,iNOS positive tumors developed more often distant metastases and the more malignant tumors showed a higher COX-2 expression.There was no correlation with other clinicopathological data. CONCLUSION:Approximately half of the cases expressed iNOS and COX-2.These two enzymes do not seem to be the key step in angiogenesis or carcinogenesis of pancreatic adenocarcinomas.Due to a low prevalence of COX-2 expression,chemoprevention of pancreatic carcinomas by COX-2 inhibitors can only achieve a limited success.展开更多
Dentin matrix metalloproteinases （MMPs） are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. Afte...Dentin matrix metalloproteinases （MMPs） are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength.Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhe- sives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.展开更多
Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elemen...Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elements in the upper crust in East China are estimated. The estimates are based on sampling of 11 451 individual rock samples over an area of 950 000 km2, from which 905 large composite samples are prepared and analyzed by 13 methods. The middle, lower and total crust compositions of East China are also estimated from studies of exposed crustal cross sections and granulite xenoliths and by correlation of seismic data with lithologies. All the tectonic units except the Tarim craton and the Qinling orogen show a four-layered crustal structure, consisting of the upper, middle, upper lower, and lowermost crusts. P-wave velocities of the bulk lower crust and total crust are 6.8–7.0 and 6:4–6.5 km/s, respectively. They are slower by 0.2–0.4 km/s than the global averages. The bulk lower crust is suggested to be intermediate with 58% SiO2 in East China. The results contrast with generally accepted global models of mafic lower crusi. The proposed total crust composition in East China is also more evolved than previous estimates and characterized by SiO2=64%, a significant negative Eu anomaly (Eu/Eu* = 0.80), deficits in Sr and transition metals, a near-arc magma La/Nd ratio (3.0), and a calculatedμ(238U/204Pb) value of 5. In addition, it has the following ratios of element pairs exhibiting similar compatibility, which are identical or close to the primitive mantle values: Zr/Hf=37, Nb/Ta=17.5, Ba/Th=87, K/Pb=0.12x104, Rb/Cs=25, Ba/Rb=8.94, Sn/Sm=0.31, Se/Cd=1.64, La/ As=10.3, Ce/Sb=271, Pb/Bi=57, Rb/TI=177, Er/Ag=52, Cu/Au=3.2×104, Sm/Mo=7.5, Nd/W=40, CI/Li=10.8, F/Nd=21.9, and La/B=1.8.展开更多
AIM: To establish a computed tomography (CT)-morphological classification for hepatic alveolar echinococcosis was the aim of the study.METHODS: The CT morphology of hepatic lesions in 228 patients with confirmed alveo...AIM: To establish a computed tomography (CT)-morphological classification for hepatic alveolar echinococcosis was the aim of the study.METHODS: The CT morphology of hepatic lesions in 228 patients with confirmed alveolar echinococcosis (AE) drawn from the Echinococcus Databank of the University Hospital of Ulm was reviewed retrospectively. For this reason, CT datasets of combined positron emission tomography (PET)-CT examinations were evaluated. The diagnosis of AE was made in patients with unequivocal seropositivity; positive histological findings following diagnostic puncture or partial resection of the liver; and/or findings typical for AE at either ultrasonography, CT, magnetic resonance imaging or PET-CT. The CT-morphological findings were grouped into the new classification scheme.RESULTS: Within the classification a lesion was dedicated to one out of five “primary morphologies” as well as to one out of six “patterns of calcification”. “primary morphology” and “pattern of calcification” are primarily focussed on separately from each other and combined, whereas the “primary morphology” V is not further characterized by a “pattern of calcification”. Based on the five primary morphologies, further descriptive sub-criteria were appended to types I-III. An analysis of the calcification pattern in relation to the primary morphology revealed the exclusive association of the central calcification with type IV primary morphology. Similarly, certain calcification patterns exhibited a clear predominance for other primary morphologies, which underscores the delimitation of the individual primary morphological types from each other. These relationships in terms of calcification patterns extend into the primary morphological sub-criteria, demonstrating the clear subordination of those criteria.CONCLUSION: The proposed CT-morphological classification (EMUC-CT) is intended to facilitate the recognition and interpretation展开更多
Intraoperative imaging is vital for accurate placement of instrumentation in spine surgery. However, the use of biplanar fluoroscopy and other intraoperative imaging modalities is associated with the risk of significa...Intraoperative imaging is vital for accurate placement of instrumentation in spine surgery. However, the use of biplanar fluoroscopy and other intraoperative imaging modalities is associated with the risk of significant radiation exposure in the patient, surgeon, and surgical staff. Radiation exposure in the form of ionizing radiation can lead to cellular damage via the induction of DNA lesions and the production of reactive oxygen species. These effects often result in cell death or genomic instability, leading to various radiation-associated pathologies including an increased risk of malignancy. In attempts to reduce radiation-associated health risks, radiation safety has become an important topic in the medical field. All practitioners, regardless of practice setting, can practice radiation safety techniques including shielding and distance to reduce radiation exposure. Additionally, optimization of fluoroscopic settings and techniques can be used as an effective method of radiation dose reduction. New imaging modalities and spinal navigation systems have also been developed in an effort to replace conventional fluoroscopy and reduce radiation doses. These modalities include Isocentric Three-Dimensional C-Arms, O-Arms, and intraoperative magnetic resonance imaging. While this influx of new technology has advanced radiation safety within the field of spine surgery, more work is still required to overcome specific limitations involving increased costs and inadequate training.展开更多
A fluid flow model consisting of Bernoulli’s law in its normal form, the equation of state of air, and the cross-stream force balance between a downward pressure gradient and the upward centrifugal force on fluid par...A fluid flow model consisting of Bernoulli’s law in its normal form, the equation of state of air, and the cross-stream force balance between a downward pressure gradient and the upward centrifugal force on fluid particles moving along curved streamlines over the top circular wing surface involving three equations in three unknowns (pressure, density and velocity) are solved to show that both density and pressure decrease upward as the inverse square of the distance from the circle’s center, and the velocity is independent of that dis-tance. These derived characteristics are used to explain the lift force on the wing in what is believed to be a novel way.展开更多
Laboratory measurements of combined P- and S-wave-velocities of eclogite from the Dabie-Sulu ultrahigh pressure metamorphic belt and from literature data show a significant increase of Poisson抯 ratio of eclogite with...Laboratory measurements of combined P- and S-wave-velocities of eclogite from the Dabie-Sulu ultrahigh pressure metamorphic belt and from literature data show a significant increase of Poisson抯 ratio of eclogite with its intrinsic water content H2O+ and thus the degree of hydration. Unaltered eclogites with H2O+<1.0% have an average Poisson抯 ratio between 0.24 and 0.25, which is identical to that calculated from single crystal elastic properties but lower than the averages (0.270.02) of measurements compiled by previous studies. Thus, the Poisson抯 ratio of unaltered eclogites is considerably lower than that of lower crustal mafic granulite and upper mantle peridotite. The lower crust and upper mantle of the Dabie ultrahigh pressure metamorphic belt, the northern and southern parts of the Tibetan Plateau as well as the central Andes, where eclogite may have formed during Mesozoic and Cenozoic tectonism, are characterized by the Poisson抯 ratio >0.26. This, together with their normal upper mantle P-wave velocities, implies that eclogites are no longer an important component of the present-day lower crust and upper mantle of these subduction-collision belts. Combined with age constraints on eclogite-facies metamor- phism and subsequent exhumation, this in turn suggests that the interval from formation to delamination of eclogites is confined to a very short period of <15 Ma.展开更多
An example of sea level pressure (SLP) and sea surface temperature (SST) is displayed for a summer month based on historical monthly mean data for the North Pacific. A double North Pacific High (NPH) co-occurred with ...An example of sea level pressure (SLP) and sea surface temperature (SST) is displayed for a summer month based on historical monthly mean data for the North Pacific. A double North Pacific High (NPH) co-occurred with a double large-scale SST maximum along 40 N. Centers of the two NPHs had very nearly the same longitudes as did the SST maxima. Seven similar coincidences happened within the 30-year records. These particular associations between extrema of SLPs and SSTs enhance a previously published conjecture that single and double NPHs are caused by heat transfer from the sea surface to the atmosphere. The eastern SST maximum is the signature of a permanent wide warm surface current flowing northeast off California. To the west of it in the summer is a transient wide warm surge of surface water flowing north as it crosses mid-latitudes. These are the heat sources that generate the single and double NPHs.展开更多
Physical separation processes are best understood in terms of the behaviour of individual ore particles.Yet,while different empirical particle-based separation modelling approaches have been developed,their predictive...Physical separation processes are best understood in terms of the behaviour of individual ore particles.Yet,while different empirical particle-based separation modelling approaches have been developed,their predictive performance has never been tested under variable process conditions.Here,we investigated the predictive performance of a state-of-the-art particle-based separation model under variable feed composition for a laboratory-scale magnetic separation of a skarn ore.Two scenarios were investigated:one in which the mass flow of the different processing streams could be measured and one in which it had to be estimated from data.In both scenarios,the predictive models were sufficiently general to predict the process outcomes of new samples of variable composition.Nevertheless,the scenario in which mass flow could be measured was4%more precise in predicting mass balances.The process behaviour of minerals present at concentrations above 0.1%by weight could be accurately predicted.Our findings indicate the potential use of this method to minimize the costs of metallurgical testwork while providing in-depth understanding of the recovery behaviour of individual ore particles.Moreover,the method may be used to establish powerful tools to forecast mineral recoveries for partly new ore types at a running mining operation.展开更多
Fluid particles in translating surface gravity waves have an orbital motion which decreases in size with increasing mean depth. These wave characteristics came from observations and were not forecast theoretically. Th...Fluid particles in translating surface gravity waves have an orbital motion which decreases in size with increasing mean depth. These wave characteristics came from observations and were not forecast theoretically. The classical potential flow model is incapable of explaining the particle movement due to the irrotational assumption and to a flaw in carrying out the method. When a wave passes by an observer from left to right, the particles move clockwise under a crest and a trough. This correct conclusion is consistent with what the incorrect standard theory implies but should not be considered to have been derived from it.展开更多
文摘The tricarboxylic acid （TCA） cycle is a central route for oxidative phosphorylation in cells, and fulfills their bioenergetic, biosynthetic, and redox balance require- ments. Despite early dogma that cancer cells bypass the TCA cycle and primarily utilize aerobic glycolysis, emerging evidence demonstrates that certain cancer cells, especially those with deregulated oncogene and tumor suppressor expression, rely heavily on the TCA cycle for energy production and macromolecule synthesis. As the field progresses, the importance of aberrant TCA cycle function in tumorigenesis and the potentials of applying small molecule inhibitors to perturb the enhanced cycle function for cancer treatment start to evolve. In this review, we summarize current knowledge about the fuels feeding the cycle, effects of oncogenes and tumor suppressors on fuel and cycle usage, common genetic alterations and deregulation of cycle enzymes, and potential therapeutic opportunities for targeting the TCA cycle in cancer cells. With the application of advanced technology and in vivo model organism studies, it is our hope that studies of this previously overlooked biochemical hub will provide fresh insights into cancer metabolism and tumorigenesis, subsequently revealing vulnerabilities for thera- peutic interventions in various cancer types.
文摘AIM: To establish an ultrasonographic classification based on a large sample of patients with confirmed hepatic alveolar echinococcosis(AE).METHODS: Clinical data and ultrasonography(US) findings of 185 patients(100 males; 85 females; mean age at diagnosis: 51.4 ± 17.6 years; mean age at time of US examination: 58.7 ± 18.2 years) were retrospectively reviewed with respect to the US morphology of hepatic AE lesions. The sonomorphological findings were grouped according to a five-part classification scheme.RESULTS: Application of the new classification resulted in the following distribution of sonomorphological patterns among the patients examined: hailstorm(54.1%); pseudocystic(13.5%); ossification(13.0%); hemangioma-like(8.1%); and metastasis-like(6.5%). Only 4.9% of lesions could not be assigned to a sonomorphological pattern.CONCLUSION: The sonomorphological classification proposed in the present study facilitates the diagnosis,interpretation and comparison of hepatic alveolar echinococcosis in routine practice and in the context of scientific studies.
文摘AIM:Cydooxygenases (COX) are key enzymes for conversion of arachidonic acid to prostaglandins.Nitric oxide synthase (NOS) is the enzyme responsible for formation of nitric oxide. Both have constitutive and inducible isoforms.The inducible isoforms (iNOS and COX-2) are of great interest as regulators of tumor angiogenesis,tumorigenesis and inflammatory processes.This study was to clarify their role in pancreatic adenocarcinomas. METHODS:We investigated the immunohistochemical iNOS and COX-2 expression in 40 pancreatic ductal adenocardnomas of different grade and stage.The results were compared with microvessel density and dinicopathological data. RESULTS:Twenty-one (52.5%) of the cases showed iNOS expression,15 (37.5%) of the cases were positive for COX-2. The immunoreaction was heterogeneously distributed within the tumors.Staining intensity was different between the tumors.No correlation between iNOS and COX-2 expression was seen.There was no relationship with microvessel density. However,iNOS positive tumors developed more often distant metastases and the more malignant tumors showed a higher COX-2 expression.There was no correlation with other clinicopathological data. CONCLUSION:Approximately half of the cases expressed iNOS and COX-2.These two enzymes do not seem to be the key step in angiogenesis or carcinogenesis of pancreatic adenocarcinomas.Due to a low prevalence of COX-2 expression,chemoprevention of pancreatic carcinomas by COX-2 inhibitors can only achieve a limited success.
文摘Dentin matrix metalloproteinases （MMPs） are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength.Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhe- sives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 49625305, 49573183, 49673184, 49794043)the State Commission of Education, the Ministry of Geology and Mineral Resources of China (Grant No. 850514)the Open Laborat
文摘Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elements in the upper crust in East China are estimated. The estimates are based on sampling of 11 451 individual rock samples over an area of 950 000 km2, from which 905 large composite samples are prepared and analyzed by 13 methods. The middle, lower and total crust compositions of East China are also estimated from studies of exposed crustal cross sections and granulite xenoliths and by correlation of seismic data with lithologies. All the tectonic units except the Tarim craton and the Qinling orogen show a four-layered crustal structure, consisting of the upper, middle, upper lower, and lowermost crusts. P-wave velocities of the bulk lower crust and total crust are 6.8–7.0 and 6:4–6.5 km/s, respectively. They are slower by 0.2–0.4 km/s than the global averages. The bulk lower crust is suggested to be intermediate with 58% SiO2 in East China. The results contrast with generally accepted global models of mafic lower crusi. The proposed total crust composition in East China is also more evolved than previous estimates and characterized by SiO2=64%, a significant negative Eu anomaly (Eu/Eu* = 0.80), deficits in Sr and transition metals, a near-arc magma La/Nd ratio (3.0), and a calculatedμ(238U/204Pb) value of 5. In addition, it has the following ratios of element pairs exhibiting similar compatibility, which are identical or close to the primitive mantle values: Zr/Hf=37, Nb/Ta=17.5, Ba/Th=87, K/Pb=0.12x104, Rb/Cs=25, Ba/Rb=8.94, Sn/Sm=0.31, Se/Cd=1.64, La/ As=10.3, Ce/Sb=271, Pb/Bi=57, Rb/TI=177, Er/Ag=52, Cu/Au=3.2×104, Sm/Mo=7.5, Nd/W=40, CI/Li=10.8, F/Nd=21.9, and La/B=1.8.
文摘AIM: To establish a computed tomography (CT)-morphological classification for hepatic alveolar echinococcosis was the aim of the study.METHODS: The CT morphology of hepatic lesions in 228 patients with confirmed alveolar echinococcosis (AE) drawn from the Echinococcus Databank of the University Hospital of Ulm was reviewed retrospectively. For this reason, CT datasets of combined positron emission tomography (PET)-CT examinations were evaluated. The diagnosis of AE was made in patients with unequivocal seropositivity; positive histological findings following diagnostic puncture or partial resection of the liver; and/or findings typical for AE at either ultrasonography, CT, magnetic resonance imaging or PET-CT. The CT-morphological findings were grouped into the new classification scheme.RESULTS: Within the classification a lesion was dedicated to one out of five “primary morphologies” as well as to one out of six “patterns of calcification”. “primary morphology” and “pattern of calcification” are primarily focussed on separately from each other and combined, whereas the “primary morphology” V is not further characterized by a “pattern of calcification”. Based on the five primary morphologies, further descriptive sub-criteria were appended to types I-III. An analysis of the calcification pattern in relation to the primary morphology revealed the exclusive association of the central calcification with type IV primary morphology. Similarly, certain calcification patterns exhibited a clear predominance for other primary morphologies, which underscores the delimitation of the individual primary morphological types from each other. These relationships in terms of calcification patterns extend into the primary morphological sub-criteria, demonstrating the clear subordination of those criteria.CONCLUSION: The proposed CT-morphological classification (EMUC-CT) is intended to facilitate the recognition and interpretation
文摘Intraoperative imaging is vital for accurate placement of instrumentation in spine surgery. However, the use of biplanar fluoroscopy and other intraoperative imaging modalities is associated with the risk of significant radiation exposure in the patient, surgeon, and surgical staff. Radiation exposure in the form of ionizing radiation can lead to cellular damage via the induction of DNA lesions and the production of reactive oxygen species. These effects often result in cell death or genomic instability, leading to various radiation-associated pathologies including an increased risk of malignancy. In attempts to reduce radiation-associated health risks, radiation safety has become an important topic in the medical field. All practitioners, regardless of practice setting, can practice radiation safety techniques including shielding and distance to reduce radiation exposure. Additionally, optimization of fluoroscopic settings and techniques can be used as an effective method of radiation dose reduction. New imaging modalities and spinal navigation systems have also been developed in an effort to replace conventional fluoroscopy and reduce radiation doses. These modalities include Isocentric Three-Dimensional C-Arms, O-Arms, and intraoperative magnetic resonance imaging. While this influx of new technology has advanced radiation safety within the field of spine surgery, more work is still required to overcome specific limitations involving increased costs and inadequate training.
文摘A fluid flow model consisting of Bernoulli’s law in its normal form, the equation of state of air, and the cross-stream force balance between a downward pressure gradient and the upward centrifugal force on fluid particles moving along curved streamlines over the top circular wing surface involving three equations in three unknowns (pressure, density and velocity) are solved to show that both density and pressure decrease upward as the inverse square of the distance from the circle’s center, and the velocity is independent of that dis-tance. These derived characteristics are used to explain the lift force on the wing in what is believed to be a novel way.
基金the National Natural Science Foundation of China(Grant Nos.40133020 , 49794043) the Ministry of Science and Technology of China(Grant No.G1999043202).
文摘Laboratory measurements of combined P- and S-wave-velocities of eclogite from the Dabie-Sulu ultrahigh pressure metamorphic belt and from literature data show a significant increase of Poisson抯 ratio of eclogite with its intrinsic water content H2O+ and thus the degree of hydration. Unaltered eclogites with H2O+<1.0% have an average Poisson抯 ratio between 0.24 and 0.25, which is identical to that calculated from single crystal elastic properties but lower than the averages (0.270.02) of measurements compiled by previous studies. Thus, the Poisson抯 ratio of unaltered eclogites is considerably lower than that of lower crustal mafic granulite and upper mantle peridotite. The lower crust and upper mantle of the Dabie ultrahigh pressure metamorphic belt, the northern and southern parts of the Tibetan Plateau as well as the central Andes, where eclogite may have formed during Mesozoic and Cenozoic tectonism, are characterized by the Poisson抯 ratio >0.26. This, together with their normal upper mantle P-wave velocities, implies that eclogites are no longer an important component of the present-day lower crust and upper mantle of these subduction-collision belts. Combined with age constraints on eclogite-facies metamor- phism and subsequent exhumation, this in turn suggests that the interval from formation to delamination of eclogites is confined to a very short period of <15 Ma.
文摘An example of sea level pressure (SLP) and sea surface temperature (SST) is displayed for a summer month based on historical monthly mean data for the North Pacific. A double North Pacific High (NPH) co-occurred with a double large-scale SST maximum along 40 N. Centers of the two NPHs had very nearly the same longitudes as did the SST maxima. Seven similar coincidences happened within the 30-year records. These particular associations between extrema of SLPs and SSTs enhance a previously published conjecture that single and double NPHs are caused by heat transfer from the sea surface to the atmosphere. The eastern SST maximum is the signature of a permanent wide warm surface current flowing northeast off California. To the west of it in the summer is a transient wide warm surge of surface water flowing north as it crosses mid-latitudes. These are the heat sources that generate the single and double NPHs.
基金the German Federal Ministry for Education and Research (BMBF) for funding the projects MoCa (grant number 033R189B) and AFK (grant number 033R128), which were essential to this studythe Saxore Bergbau GmbH for providing the samples for this studySabine Gilbricht (TU Bergakademie Freiberg) for support during SEM-MLA data acquisition
文摘Physical separation processes are best understood in terms of the behaviour of individual ore particles.Yet,while different empirical particle-based separation modelling approaches have been developed,their predictive performance has never been tested under variable process conditions.Here,we investigated the predictive performance of a state-of-the-art particle-based separation model under variable feed composition for a laboratory-scale magnetic separation of a skarn ore.Two scenarios were investigated:one in which the mass flow of the different processing streams could be measured and one in which it had to be estimated from data.In both scenarios,the predictive models were sufficiently general to predict the process outcomes of new samples of variable composition.Nevertheless,the scenario in which mass flow could be measured was4%more precise in predicting mass balances.The process behaviour of minerals present at concentrations above 0.1%by weight could be accurately predicted.Our findings indicate the potential use of this method to minimize the costs of metallurgical testwork while providing in-depth understanding of the recovery behaviour of individual ore particles.Moreover,the method may be used to establish powerful tools to forecast mineral recoveries for partly new ore types at a running mining operation.
文摘Fluid particles in translating surface gravity waves have an orbital motion which decreases in size with increasing mean depth. These wave characteristics came from observations and were not forecast theoretically. The classical potential flow model is incapable of explaining the particle movement due to the irrotational assumption and to a flaw in carrying out the method. When a wave passes by an observer from left to right, the particles move clockwise under a crest and a trough. This correct conclusion is consistent with what the incorrect standard theory implies but should not be considered to have been derived from it.
