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Jennming Yang - One of the best experts on this subject based on the ideXlab platform.
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in situ formation of tic particle reinforced stainless steel matrix nanocomposites during ball milling feedstock Powder Preparation for selective laser melting at various energy densities
Powder Technology, 2018Co-Authors: Bandar Almangour, Dariusz Grzesiak, Jennming YangAbstract:Abstract 316L–Ti–graphite mixed Powders were subjected to mechanical alloying (MA) for milling times ranging from 4 to 35 h. After 24 h of milling, TiC particles began forming in situ within a steel matrix via MA. The TiC phase formed due to the gradual interdiffusion of Ti into the graphite lattice. Evolutions of the phases, microstructure, and composition of the Powders with varied milling times were investigated. The results showed that irregularly shaped particles formed initially; these particles flattened after 10 h of milling, coarsened after 24 h of milling, and finally became fine and uniform when milled for > 24 h. Micrographs of the 35-h milled feedstock Powder showed 20-nm-diameter TiC nanoparticles uniformly distributed in the 316L matrix. Then, the 35-h milled feedstock Powders were processed by selective laser melting (SLM), an additive manufacturing process. The effects of the laser energy density (η) used during SLM on the microstructure, hardness, and tribological behavior of the SLM-processed parts were investigated. TiC particles were uniformly distributed within the steel matrix for all η values. With increasing η, however, the microstructure tended to coarsen because of the slower cooling rate. The applied η also influenced the hardness and wear rate. The hardest samples were obtained at η of 67 J/mm3, and the optimum wear resistance was measured at η of 200 J/mm3. A continuous, well-adhered strain-hardened tribolayer demonstrated the best wear resistance.
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selective laser melting of tib2 316l stainless steel composites the roles of Powder Preparation and hot isostatic pressing post treatment
Powder Technology, 2017Co-Authors: Bandar Almangour, Dariusz Grzesiak, Jennming YangAbstract:Abstract Selective laser melting (SLM), a promising additive manufacturing technology, was used to fabricate TiB 2 /316L stainless steel composites. An important factor in manufacturing composites via SLM is feedstock Powder Preparation. In this work, the Powders were prepared by either direct mixing or ball milling. The evolution of constituent phases, microstructural features, and size distribution with milling time was investigated. This research determined that Powder particles were both coarsened and refined during the early stages of milling (0–6 h), depending on the milling time. After 8 h of milling, the Powders exhibited a wide size distribution and stable spherical morphology, while the average crystallite size of the stainless steel matrix phase significantly decreased to 11.11 nm due to severe plastic deformation. The Powders obtained after 8 h of mixing or milling were processed via SLM, and the microstructures exhibited a continuous ring-like structure of uniformly dispersed TiB 2 particles. The hardness of the nanocomposite sample prepared from the ball milled Powder exceeded that for samples made with the directly mixed Powder, but only for those with the highest content of 15 vol.% TiB 2 reinforcement particles, due to finer particle sizes and enhancement of the wetting behavior in the molten pool. To increase the final density of these SLM-fabricated components with high hardnesses, a hot isostatic pressing (HIP) post-treatment was applied. The microstructural characteristics of the HIPed samples evolved with HIP holding time from equiaxed grains to segregated regions of coalesced reinforcement particles. In addition, significant drops in hardness and wear resistance values were observed after HIP treatment due to the high-temperature annealing effect.
Andrew Clark - One of the best experts on this subject based on the ideXlab platform.
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a new method for bronchial provocation testing in asthmatic subjects using a dry Powder of mannitol
American Journal of Respiratory and Critical Care Medicine, 1997Co-Authors: Sandra D Anderson, John D Brannan, Joanne F Spring, Natasha Spalding, L T Rodwell, Kim H Chan, Igor Gonda, Andrew J Walsh, Andrew ClarkAbstract:We developed a bronchial provocation test (BPT) with a dry Powder Preparation of mannitol. The mannitol was inhaled from gelatin capsules containing 5, 10, 20, or 40 mg to a cumulative dose of 635 mg, and was delivered via an inhalator, Halermatic, or Dinkihaler device. We studied the airway sensitivity to inhaled mannitol, the repeatability of the response, and the recovery after challenge in 43 asthmatic subjects 18 to 39 yr of age who had a 20% decrease in FEV1 in response to inhaling a 4.5% NaCl. We compared this with the airway response to methacholine in 25 subjects. The geometric mean (GM) for the dose of dry mannitol required to reduce the FEV1 by 15% of the baseline value (PD15) was 64 mg, with a 95% confidence interval (CI) of 45 to 91. Subjects responsive to mannitol had a PD20 to metacholine of < 7.8 mumol, with a GM of 0.7 mumol (CI: 0.4 to 1.2). For the first of two challenges to mannitol the PD15 was 59 mg (CI: 36 to 97) and for the second the PD15 was 58 mg (CI: 35 to 94) p = 0.91 (n = 23). Spontaneous recovery to within 5% of baseline occurred within 60 min and within 10 min after 0.5 mg terbutaline sulfate was inhaled. Arterial oxygen saturation (SaO2) remained at 93% or above during mannitol challenge. Subjects tolerated the inhalation of the mannitol well. A dry Powder Preparation of mannitol may be suitable to develop for bronchial provocation testing.
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a new method for bronchial provocation testing in asthmatic subjects using a dry Powder of mannitol
American Journal of Respiratory and Critical Care Medicine, 1997Co-Authors: Sandra D Anderson, John D Brannan, Joanne F Spring, Natasha Spalding, L T Rodwell, Kim H Chan, Igor Gonda, Andrew J Walsh, Andrew ClarkAbstract:We developed a bronchial provocation test (BPT) with a dry Powder Preparation of mannitol. The mannitol was inhaled from gelatin capsules containing 5, 10, 20, or 40 mg to a cumulative dose of 635 mg, and was delivered via an inhalator, Halermatic, or Dinkihaler device. We studied the airway sensitivity to inhaled mannitol, the repeatability of the response, and the recovery after challenge in 43 asthmatic subjects 18 to 39 yr of age who had a 20% decrease in FEV1 in response to inhaling a 4.5% NaCl. We compared this with the airway response to methacholine in 25 subjects. The geometric mean (GM) for the dose of dry mannitol required to reduce the FEV1 by 15% of the baseline value (PD15) was 64 mg, with a 95% confidence interval (CI) of 45 to 91. Subjects responsive to mannitol had a PD20 to metacholine of < 7.8 mumol, with a GM of 0.7 mumol (CI: 0.4 to 1.2). For the first of two challenges to mannitol the PD15 was 59 mg (CI: 36 to 97) and for the second the PD15 was 58 mg (CI: 35 to 94) p = 0.91 (n = 23). Spontaneous recovery to within 5% of baseline occurred within 60 min and within 10 min after 0.5 mg terbutaline sulfate was inhaled. Arterial oxygen saturation (SaO2) remained at 93% or above during mannitol challenge. Subjects tolerated the inhalation of the mannitol well. A dry Powder Preparation of mannitol may be suitable to develop for bronchial provocation testing.
Bandar Almangour - One of the best experts on this subject based on the ideXlab platform.
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in situ formation of tic particle reinforced stainless steel matrix nanocomposites during ball milling feedstock Powder Preparation for selective laser melting at various energy densities
Powder Technology, 2018Co-Authors: Bandar Almangour, Dariusz Grzesiak, Jennming YangAbstract:Abstract 316L–Ti–graphite mixed Powders were subjected to mechanical alloying (MA) for milling times ranging from 4 to 35 h. After 24 h of milling, TiC particles began forming in situ within a steel matrix via MA. The TiC phase formed due to the gradual interdiffusion of Ti into the graphite lattice. Evolutions of the phases, microstructure, and composition of the Powders with varied milling times were investigated. The results showed that irregularly shaped particles formed initially; these particles flattened after 10 h of milling, coarsened after 24 h of milling, and finally became fine and uniform when milled for > 24 h. Micrographs of the 35-h milled feedstock Powder showed 20-nm-diameter TiC nanoparticles uniformly distributed in the 316L matrix. Then, the 35-h milled feedstock Powders were processed by selective laser melting (SLM), an additive manufacturing process. The effects of the laser energy density (η) used during SLM on the microstructure, hardness, and tribological behavior of the SLM-processed parts were investigated. TiC particles were uniformly distributed within the steel matrix for all η values. With increasing η, however, the microstructure tended to coarsen because of the slower cooling rate. The applied η also influenced the hardness and wear rate. The hardest samples were obtained at η of 67 J/mm3, and the optimum wear resistance was measured at η of 200 J/mm3. A continuous, well-adhered strain-hardened tribolayer demonstrated the best wear resistance.
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selective laser melting of tib2 316l stainless steel composites the roles of Powder Preparation and hot isostatic pressing post treatment
Powder Technology, 2017Co-Authors: Bandar Almangour, Dariusz Grzesiak, Jennming YangAbstract:Abstract Selective laser melting (SLM), a promising additive manufacturing technology, was used to fabricate TiB 2 /316L stainless steel composites. An important factor in manufacturing composites via SLM is feedstock Powder Preparation. In this work, the Powders were prepared by either direct mixing or ball milling. The evolution of constituent phases, microstructural features, and size distribution with milling time was investigated. This research determined that Powder particles were both coarsened and refined during the early stages of milling (0–6 h), depending on the milling time. After 8 h of milling, the Powders exhibited a wide size distribution and stable spherical morphology, while the average crystallite size of the stainless steel matrix phase significantly decreased to 11.11 nm due to severe plastic deformation. The Powders obtained after 8 h of mixing or milling were processed via SLM, and the microstructures exhibited a continuous ring-like structure of uniformly dispersed TiB 2 particles. The hardness of the nanocomposite sample prepared from the ball milled Powder exceeded that for samples made with the directly mixed Powder, but only for those with the highest content of 15 vol.% TiB 2 reinforcement particles, due to finer particle sizes and enhancement of the wetting behavior in the molten pool. To increase the final density of these SLM-fabricated components with high hardnesses, a hot isostatic pressing (HIP) post-treatment was applied. The microstructural characteristics of the HIPed samples evolved with HIP holding time from equiaxed grains to segregated regions of coalesced reinforcement particles. In addition, significant drops in hardness and wear resistance values were observed after HIP treatment due to the high-temperature annealing effect.
Yuanzheng Yue - One of the best experts on this subject based on the ideXlab platform.
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fabrication of highly insulating foam glass made from crt panel glass
Ceramics International, 2015Co-Authors: Jakob Konig, Rasmus Rosenlund Petersen, Yuanzheng YueAbstract:Abstract We prepared low-density foam glasses from cathode-ray-tube panel glass using carbon and MnO 2 as the foaming agents. We investigated the influence of the carbon and MnO 2 concentrations, the glass-Powder Preparation and the foaming conditions on the density and homogeneity of the pore structure and the dependence of the thermal conductivity on the foam density. The results show that the moderate foaming effect of the carbon is greatly improved by the addition of MnO 2 . A density as low as 131 kg m −3 can be achieved with fine glass Powder. The foam density has a slight dependence on the carbon and MnO 2 concentrations, but it is mainly affected by the foaming temperature and the time. The thermal conductivity of the foam-glass samples is lower than that of commercial foam glasses with the same density. The lowest value was determined to be 42 mW m −1 K −1 for a foam glass with a density of 131 kg m −3 . A further improvement in the closed porosity could potentially decrease the thermal conductivity even further, and thus our approach has great potential in terms of a thermal insulation material.
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influence of the glass calcium carbonate mixture s characteristics on the foaming process and the properties of the foam glass
Journal of The European Ceramic Society, 2014Co-Authors: Jakob Konig, Rasmus Rosenlund Petersen, Yuanzheng YueAbstract:Abstract We prepared foam glasses from cathode-ray-tube panel glass and CaCO 3 as a foaming agent. We investigated the influences of Powder Preparation, CaCO 3 concentration and foaming temperature and time on the density, porosity and homogeneity of the foam glasses. The results show that the decomposition kinetics of CaCO 3 has a strong influence on the foaming process. The decomposition temperature can be modified by varying the milling time of the glass–CaCO 3 mixture and thus for a specific CaCO 3 concentration an optimum milling time exists, at which a minimum in density and a homogeneous closed porosity are obtained. Under the optimum Preparation conditions the samples exhibit a density of 260 kg/m 3 . The thermal conductivity of the foam glass was measured to be 50–53 mW/(m K). The observed dependence of the foaming process on the decomposition kinetics of the foaming agent can be applied as a universal rule for foaming processes based on thermal decomposition.
Sandra D Anderson - One of the best experts on this subject based on the ideXlab platform.
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inhalation of dry Powder mannitol increases mucociliary clearance
European Respiratory Journal, 1997Co-Authors: Evangelia Daviskas, Sandra D Anderson, John D Brannan, Hakkim Chan, Stefan Eberl, George J BautovichAbstract:Inhalation of hypertonic saline stimulates mucociliary clearance (MCC) in healthy subjects and those with obstructive lung disease. We investigated the effect of inhaling the osmotic agent mannitol on MCC. We used a dry-Powder Preparation of mannitol British Pharmacopea (BP) which was encapsulated and delivered using a Dinkihaler. MCC was measured for 75 min in six asthmatic and six healthy subjects on two occasions before and after the mannitol inhalation or its control, using 99mTc-sulphur colloid and a gamma camera. The inhaled dose of mannitol was 267+/-171 mg (mean+/-SD) and 400 mg and the percentage fall in forced expiratory volume in one second (FEV1) was 22+/-3 and 4+/-2% in the asthmatic and healthy subjects, respectively. The total clearance in the whole right lung for the 60 min from the start of inhalation of mannitol was greater by 263+/-11.9% in the asthmatic and 18.1+/-4.9% in the healthy subjects compared to the control. The total clearance over 75 min was 54.7+/-9.6% and 33.6+/-9.4% on the mannitol and control day (p<0.002), respectively, in the asthmatic subjects and 40.5+/-7.1% and 24.8+/-7.8% (p<0.002) in the healthy subjects. In conclusion, inhalation of dry-Powder mannitol increases mucociliary clearance in asthmatic and healthy subjects and may benefit patients with abnormal mucociliary clearance.
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a new method for bronchial provocation testing in asthmatic subjects using a dry Powder of mannitol
American Journal of Respiratory and Critical Care Medicine, 1997Co-Authors: Sandra D Anderson, John D Brannan, Joanne F Spring, Natasha Spalding, L T Rodwell, Kim H Chan, Igor Gonda, Andrew J Walsh, Andrew ClarkAbstract:We developed a bronchial provocation test (BPT) with a dry Powder Preparation of mannitol. The mannitol was inhaled from gelatin capsules containing 5, 10, 20, or 40 mg to a cumulative dose of 635 mg, and was delivered via an inhalator, Halermatic, or Dinkihaler device. We studied the airway sensitivity to inhaled mannitol, the repeatability of the response, and the recovery after challenge in 43 asthmatic subjects 18 to 39 yr of age who had a 20% decrease in FEV1 in response to inhaling a 4.5% NaCl. We compared this with the airway response to methacholine in 25 subjects. The geometric mean (GM) for the dose of dry mannitol required to reduce the FEV1 by 15% of the baseline value (PD15) was 64 mg, with a 95% confidence interval (CI) of 45 to 91. Subjects responsive to mannitol had a PD20 to metacholine of < 7.8 mumol, with a GM of 0.7 mumol (CI: 0.4 to 1.2). For the first of two challenges to mannitol the PD15 was 59 mg (CI: 36 to 97) and for the second the PD15 was 58 mg (CI: 35 to 94) p = 0.91 (n = 23). Spontaneous recovery to within 5% of baseline occurred within 60 min and within 10 min after 0.5 mg terbutaline sulfate was inhaled. Arterial oxygen saturation (SaO2) remained at 93% or above during mannitol challenge. Subjects tolerated the inhalation of the mannitol well. A dry Powder Preparation of mannitol may be suitable to develop for bronchial provocation testing.
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a new method for bronchial provocation testing in asthmatic subjects using a dry Powder of mannitol
American Journal of Respiratory and Critical Care Medicine, 1997Co-Authors: Sandra D Anderson, John D Brannan, Joanne F Spring, Natasha Spalding, L T Rodwell, Kim H Chan, Igor Gonda, Andrew J Walsh, Andrew ClarkAbstract:We developed a bronchial provocation test (BPT) with a dry Powder Preparation of mannitol. The mannitol was inhaled from gelatin capsules containing 5, 10, 20, or 40 mg to a cumulative dose of 635 mg, and was delivered via an inhalator, Halermatic, or Dinkihaler device. We studied the airway sensitivity to inhaled mannitol, the repeatability of the response, and the recovery after challenge in 43 asthmatic subjects 18 to 39 yr of age who had a 20% decrease in FEV1 in response to inhaling a 4.5% NaCl. We compared this with the airway response to methacholine in 25 subjects. The geometric mean (GM) for the dose of dry mannitol required to reduce the FEV1 by 15% of the baseline value (PD15) was 64 mg, with a 95% confidence interval (CI) of 45 to 91. Subjects responsive to mannitol had a PD20 to metacholine of < 7.8 mumol, with a GM of 0.7 mumol (CI: 0.4 to 1.2). For the first of two challenges to mannitol the PD15 was 59 mg (CI: 36 to 97) and for the second the PD15 was 58 mg (CI: 35 to 94) p = 0.91 (n = 23). Spontaneous recovery to within 5% of baseline occurred within 60 min and within 10 min after 0.5 mg terbutaline sulfate was inhaled. Arterial oxygen saturation (SaO2) remained at 93% or above during mannitol challenge. Subjects tolerated the inhalation of the mannitol well. A dry Powder Preparation of mannitol may be suitable to develop for bronchial provocation testing.