The influence of cooling rate on the microstructure and mechanical properties of two new ultrahigh-strength steels(UHSSs)with different levels of C,Cr and Ni has been evaluated for the as-cooled and untempered conditi...The influence of cooling rate on the microstructure and mechanical properties of two new ultrahigh-strength steels(UHSSs)with different levels of C,Cr and Ni has been evaluated for the as-cooled and untempered condition.One UHSS had higher contents of C and Cr,while the other one had a higher Ni content.On the basis of dilatation curves,microstructures,macrohardness and microhardness,continuous cooling transformation diagrams were constructed as a guide to heat treatment possibilities.Cooling rates(CRs)of 60,1 and 0.01°C/s were selected for more detailed investigations.Microstructural characterization was made by laser scanning confocal microscopy,field emission scanning electron microscopy combined with electron backscatter diffraction,electron probe microanalysis and X-ray diffraction.Mechanical properties were characterized using macrohardness,tensile and Charpy V-notch impact tests.UHSS with the higher C and Cr contents showed lower transformation temperatures and slower bainite formation kinetics than that with the higher Ni content.Higher cooling rates led to lower volume fractions and carbon contents of retained austenite together with finer prior austenite grain size,as well as effective final grain size and lath size.These changes were accompanied by higher yield and tensile strengths.The best combinations of strength and toughness were obtained with martensitic microstructures and by avoiding the formation of granular bainite accompanied by proeutectoid carbides at low CR.For the cooling rates studied,UHSS with the higher C and Cr contents showed the higher hardness and strength but at the cost of toughness.展开更多
Objective:To determine prevalence of hyponatremia in acute medical admissions in Northern Australasia.Methods:We studied 469 consecutive acute medical admissions to a hospital in Australia's Far North Queensland d...Objective:To determine prevalence of hyponatremia in acute medical admissions in Northern Australasia.Methods:We studied 469 consecutive acute medical admissions to a hospital in Australia's Far North Queensland during the colder months of June and July 2012.Prevalence of hyponatremia and its relationship with gender,age,diagnosis and prognosis in acute medical admissions were investigated.Results:On admission,hyponatremia(plasma sodium<136 mmol/L)was present in 39.4%of patients,with mild(130—135 mmol/L),moderate(126-129 mmol/L)and severe?126 mmol/L)hyponatremia being present in 25.2%,10.7*and 3.6*respectively.Overall,adding together admission hyponatremia with that developing during admission,45.2%of patients were affected with 11.5%moderate hyponatremia cases and 4.1%severe ones.Hypokalemia and hyperkalemia were present in 17.0%and 18.1*,respectively.Overall,275/469 patients(58.6*)presented with an electrolyte abnormality.There were significant correlations of hyponatremia with age but not with gender and in-hospital mortality.Prevalence of hyponatremia was high across all diagnostic categories.Conclusions:The prevalence of hyponatremia appears to be high in the tropical North Australian population,being the highest prevalence reported amongst acute hospital admissions.The previously reported correlations with age and mortality do appear to hold good for this population with a high prevalence of electrolyte disorders.Further prospective analysis on a larger population in the area is needed to confirm our findings.展开更多
Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. th...Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. the use of economic low-alloy compositions processed via low-cost air induction melting and electroslag refining (ESR). In this work the yield of alloying elements and the removal of the impurities nitrogen, sulphur and phosphorus as a result of electroslag refining (ESR) in a newly developed CrNiMoWMnV ultrahigh-strength steel (UHSS) have been studied in relation to their activities in the molten metal pool. Six experimental heats of CrNiMoWMnV UHSS with different chemical compositions were designed, melted in an induction furnace (IF) and refined using ESR. This was followed by hot forging of the ingots at 1100°C to 950°C. ESR using a CaF2-CaO-Al2O3 slag system led to a high yield in Cr, Ni, Mo, W, Mn and V, while the yield of Si is low. The desulphurization of all six UHSS grades was pronounced with most of the sulphur removed either to the slag or by gas reactions. The degree of dephosphorization was only 5% irrespective of the steel composition. On the other hand, denitrification (removal of nitrogen) was achieved. It ranged from 8% to 63% depending on the steel composition. The yield of the alloying elements and removal of impurities from the steel during ESR depends on the chemical and physical properties of the ESR slag and the activity of the elements in the molten state, taking into account elemental interactions.展开更多
Professor Jonathan Locke Hart answers our questions about Comparative Literature in Canada,Canadian indigenous literary traditions,Shakespeare,and the dominance of American academia,and the English language.He refers ...Professor Jonathan Locke Hart answers our questions about Comparative Literature in Canada,Canadian indigenous literary traditions,Shakespeare,and the dominance of American academia,and the English language.He refers to a wide range of texts and scholars,his personal experience as a poet and scholar,and comments on the potential future of our shared disciplines.展开更多
When one prepares to write about World Literature,one usually begins by looking up references to the word"Weltliteratur"in the works of Johann Wolfgang von Goethe,then meandering along through two centuries ...When one prepares to write about World Literature,one usually begins by looking up references to the word"Weltliteratur"in the works of Johann Wolfgang von Goethe,then meandering along through two centuries of literary criticism until one safely approaches the novel literary theories of the globalized 21st century.The persistence of the un-Anglicized word Weltliteratur in discussions of Goethe,Marx,et al.,is a fossil of a time when expertise in the subject meant fluency in English,French,and German(perhaps along with Latin,ancient Greek,and a few other Romance and Slavic languages);a time when ein wenig untranslated German was permissible,even when dispensable.Even when we outlive past assumptions,our disciplines preserve their remains.What should we make of the remains of World Literature?What should we do with our fossilized critical assumptions?展开更多
文摘The influence of cooling rate on the microstructure and mechanical properties of two new ultrahigh-strength steels(UHSSs)with different levels of C,Cr and Ni has been evaluated for the as-cooled and untempered condition.One UHSS had higher contents of C and Cr,while the other one had a higher Ni content.On the basis of dilatation curves,microstructures,macrohardness and microhardness,continuous cooling transformation diagrams were constructed as a guide to heat treatment possibilities.Cooling rates(CRs)of 60,1 and 0.01°C/s were selected for more detailed investigations.Microstructural characterization was made by laser scanning confocal microscopy,field emission scanning electron microscopy combined with electron backscatter diffraction,electron probe microanalysis and X-ray diffraction.Mechanical properties were characterized using macrohardness,tensile and Charpy V-notch impact tests.UHSS with the higher C and Cr contents showed lower transformation temperatures and slower bainite formation kinetics than that with the higher Ni content.Higher cooling rates led to lower volume fractions and carbon contents of retained austenite together with finer prior austenite grain size,as well as effective final grain size and lath size.These changes were accompanied by higher yield and tensile strengths.The best combinations of strength and toughness were obtained with martensitic microstructures and by avoiding the formation of granular bainite accompanied by proeutectoid carbides at low CR.For the cooling rates studied,UHSS with the higher C and Cr contents showed the higher hardness and strength but at the cost of toughness.
文摘Objective:To determine prevalence of hyponatremia in acute medical admissions in Northern Australasia.Methods:We studied 469 consecutive acute medical admissions to a hospital in Australia's Far North Queensland during the colder months of June and July 2012.Prevalence of hyponatremia and its relationship with gender,age,diagnosis and prognosis in acute medical admissions were investigated.Results:On admission,hyponatremia(plasma sodium<136 mmol/L)was present in 39.4%of patients,with mild(130—135 mmol/L),moderate(126-129 mmol/L)and severe?126 mmol/L)hyponatremia being present in 25.2%,10.7*and 3.6*respectively.Overall,adding together admission hyponatremia with that developing during admission,45.2%of patients were affected with 11.5%moderate hyponatremia cases and 4.1%severe ones.Hypokalemia and hyperkalemia were present in 17.0%and 18.1*,respectively.Overall,275/469 patients(58.6*)presented with an electrolyte abnormality.There were significant correlations of hyponatremia with age but not with gender and in-hospital mortality.Prevalence of hyponatremia was high across all diagnostic categories.Conclusions:The prevalence of hyponatremia appears to be high in the tropical North Australian population,being the highest prevalence reported amongst acute hospital admissions.The previously reported correlations with age and mortality do appear to hold good for this population with a high prevalence of electrolyte disorders.Further prospective analysis on a larger population in the area is needed to confirm our findings.
文摘Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. the use of economic low-alloy compositions processed via low-cost air induction melting and electroslag refining (ESR). In this work the yield of alloying elements and the removal of the impurities nitrogen, sulphur and phosphorus as a result of electroslag refining (ESR) in a newly developed CrNiMoWMnV ultrahigh-strength steel (UHSS) have been studied in relation to their activities in the molten metal pool. Six experimental heats of CrNiMoWMnV UHSS with different chemical compositions were designed, melted in an induction furnace (IF) and refined using ESR. This was followed by hot forging of the ingots at 1100°C to 950°C. ESR using a CaF2-CaO-Al2O3 slag system led to a high yield in Cr, Ni, Mo, W, Mn and V, while the yield of Si is low. The desulphurization of all six UHSS grades was pronounced with most of the sulphur removed either to the slag or by gas reactions. The degree of dephosphorization was only 5% irrespective of the steel composition. On the other hand, denitrification (removal of nitrogen) was achieved. It ranged from 8% to 63% depending on the steel composition. The yield of the alloying elements and removal of impurities from the steel during ESR depends on the chemical and physical properties of the ESR slag and the activity of the elements in the molten state, taking into account elemental interactions.
文摘Professor Jonathan Locke Hart answers our questions about Comparative Literature in Canada,Canadian indigenous literary traditions,Shakespeare,and the dominance of American academia,and the English language.He refers to a wide range of texts and scholars,his personal experience as a poet and scholar,and comments on the potential future of our shared disciplines.
文摘When one prepares to write about World Literature,one usually begins by looking up references to the word"Weltliteratur"in the works of Johann Wolfgang von Goethe,then meandering along through two centuries of literary criticism until one safely approaches the novel literary theories of the globalized 21st century.The persistence of the un-Anglicized word Weltliteratur in discussions of Goethe,Marx,et al.,is a fossil of a time when expertise in the subject meant fluency in English,French,and German(perhaps along with Latin,ancient Greek,and a few other Romance and Slavic languages);a time when ein wenig untranslated German was permissible,even when dispensable.Even when we outlive past assumptions,our disciplines preserve their remains.What should we make of the remains of World Literature?What should we do with our fossilized critical assumptions?
