The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investiga...The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investigated.The hypereutectic Al-Si-Si C composite was prepared by stir casting route.The hardness,ultimate tensile strength and yield strength of the composite are increased by 17%,38%,and 30%respectively compared with those of the matrix alloy,while the elongation of the composite is decreased by 48%compared with that of the matrix alloy.The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance.The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy(HR FESEM)and wear mechanism was analyzed for low and high load regimes.展开更多
The aim was to experimentally evaluate the antioxidant capacity of different types of bread and of the relative flour used for bread production utilizing a superoxide dismutase (SOD) biosensor recently developed by ...The aim was to experimentally evaluate the antioxidant capacity of different types of bread and of the relative flour used for bread production utilizing a superoxide dismutase (SOD) biosensor recently developed by the present authors. Measurements were carried out by comparing the biosensor response to the concentration of superoxide radical produced in solution using a xanthine/xanthine oxidase system in the presence and in the absence of the antioxidant sample considered, respectively. Precision of antioxidant capacity measures for crust and crumb of the different breads was found to be good (RS D% ≤ 8%) and acceptable for the watery suspension and filtrate of the different flours studied (RSD% ≤ 12%). The obtained results indicated that general flours show higher antioxidant capacity values than the corresponding breads and that crusts show always an antioxidant capacity definitely larger than the crumb. Lastly, the antioxidant capacity values were compared with those of almond, red pepper and strawberry, three foods containing powerful natural antioxidants.展开更多
Throughout Western music history, pre-existing material has long been the aesthetic core of a new composition. Yet there has never been such an epoch as our time in which using pre-existing material, melodic quotation...Throughout Western music history, pre-existing material has long been the aesthetic core of a new composition. Yet there has never been such an epoch as our time in which using pre-existing material, melodic quotation in particular, features so extensively in works of many of the composers. The aim of this paper is to investigate how the use of quoted tunes in a musical piece operates in an interwoven complex where time and space are of the essence. A quote is able to oscillate perpetually between one’s mental worlds of the memorable past and the imaginative present when it is highlighted enough to be recognizable from its surrounding context. Upon interpreting the use of quotation in various contexts, the aesthetic object, I argue, is the shift from original to quoted music, and vice versa. And listeners can respond aesthetically to the quotation itself even without knowledge of its provenance and textual or referential content.展开更多
This paper proposes new ways to understand the sense of universality in music through a reflection and analysis of George Crumb's Black Angels (Images 1): Thirteen lmages from the Dark Land, one of the defining mu...This paper proposes new ways to understand the sense of universality in music through a reflection and analysis of George Crumb's Black Angels (Images 1): Thirteen lmages from the Dark Land, one of the defining musical expressions of the Vietnam War era. It centers on an analysis of the relationship of the body/self to an "ecology of war" produced through Crumb's music that renders these selves indistinct within this musical geography. The selves that inhabit Black Angels could be that of anybody in particular since Crumb seeks to invoke in his music the primeval experience of terror that inhabits in all of us as the inheritors of mankind's violence. This sense of the universal militates against the desirable qualities of popular music that rely on the production of autonomous and singular selves that make the distinction between enemy and friend possible and distinct. We focus on Crumb's use of archaisms, his construction of time in this piece, and the author's overall purpose to invoke a time of war rather than to reflect the conditions of war, in order to delineate the contours of the universal time and space producing the undifferentiated primeval self of war. We conclude that although Crumb's rejection of the national self deprives the piece of a salient place in the popular cannon of the war, it has left an intellectual legacy on the times of the Vietnam War that deserves to be preserved.展开更多
Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile co...Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile contaminants such as furan and its derivatives, and present a volatile profile of the most common furan derivatives in the described products. To measure concentration of chemical compounds such as furan and furan derivatives, fast and effective solid-phase micro-extraction/gas chromatography/mass spectrometry (SPME/GC/MS) methods were adapted. This study showed the differences in furan occurrence between Pytlowy and Staropolski, however, the greater differences were observed between different times and temperatures of baking rather than between the bread types. Clearly, the higher concentrations were found in products prepared during the longest baking time period of 50 min, and temperatures of 230 ℃ and 240 ℃. The highest furan level was detected in Staropolski 28.89 ± 1.16/μg/kg, baked for 50 min at 230 ℃ in bread crust. The volatile fraction of bread crust was composed of 5-9 furan derivatives while crumb layer contained only furan-2-pentyl. It was concluded that furan is present in almost each type of bread and percentage of furan derivatives in all volatile fractions ranged from 0.5 % to 60.6% in crust of examined bars.展开更多
The incision of the Sanmen Gorge marks the birth of the modern Yellow River,but its timing varies from the late Miocene-early Pliocene to the late Pleistocene(~0.15 Ma),and the suggested forcing mechanisms vary from t...The incision of the Sanmen Gorge marks the birth of the modern Yellow River,but its timing varies from the late Miocene-early Pliocene to the late Pleistocene(~0.15 Ma),and the suggested forcing mechanisms vary from the uplift of the Tibetan Plateau to global climate change.Here,we report sedimentologic,geochronologic,and provenance data from a drill core near the Sanmen Gorge,the last gorge along the main course of the Yellow River.Our results indicate that typical river channel deposits,with detritus from the Ordos Block in the upstream regions,started to accumulate in the Sanmen Gorge at~1.25 Ma.When integrated with river terrace evidence from the upstream and downstream regions,the results provide robust evidence that the final integration of the modern Yellow River occurred at~1.25 Ma,consistent with the beginning of the Mid-Pleistocene transition(MPT).We propose that the accelerated lowering of eustatic sea level during the MPT may play as important a role as tectonism in driving the birth and evolution of the modern Yellow River.展开更多
基金the financial support received to the first author as a scholarship from MHRD,Government of India.
文摘The microstructure,mechanical properties,and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al-Si-Si C composite and its matrix alloy were investigated.The hypereutectic Al-Si-Si C composite was prepared by stir casting route.The hardness,ultimate tensile strength and yield strength of the composite are increased by 17%,38%,and 30%respectively compared with those of the matrix alloy,while the elongation of the composite is decreased by 48%compared with that of the matrix alloy.The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance.The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy(HR FESEM)and wear mechanism was analyzed for low and high load regimes.
文摘The aim was to experimentally evaluate the antioxidant capacity of different types of bread and of the relative flour used for bread production utilizing a superoxide dismutase (SOD) biosensor recently developed by the present authors. Measurements were carried out by comparing the biosensor response to the concentration of superoxide radical produced in solution using a xanthine/xanthine oxidase system in the presence and in the absence of the antioxidant sample considered, respectively. Precision of antioxidant capacity measures for crust and crumb of the different breads was found to be good (RS D% ≤ 8%) and acceptable for the watery suspension and filtrate of the different flours studied (RSD% ≤ 12%). The obtained results indicated that general flours show higher antioxidant capacity values than the corresponding breads and that crusts show always an antioxidant capacity definitely larger than the crumb. Lastly, the antioxidant capacity values were compared with those of almond, red pepper and strawberry, three foods containing powerful natural antioxidants.
文摘Throughout Western music history, pre-existing material has long been the aesthetic core of a new composition. Yet there has never been such an epoch as our time in which using pre-existing material, melodic quotation in particular, features so extensively in works of many of the composers. The aim of this paper is to investigate how the use of quoted tunes in a musical piece operates in an interwoven complex where time and space are of the essence. A quote is able to oscillate perpetually between one’s mental worlds of the memorable past and the imaginative present when it is highlighted enough to be recognizable from its surrounding context. Upon interpreting the use of quotation in various contexts, the aesthetic object, I argue, is the shift from original to quoted music, and vice versa. And listeners can respond aesthetically to the quotation itself even without knowledge of its provenance and textual or referential content.
文摘This paper proposes new ways to understand the sense of universality in music through a reflection and analysis of George Crumb's Black Angels (Images 1): Thirteen lmages from the Dark Land, one of the defining musical expressions of the Vietnam War era. It centers on an analysis of the relationship of the body/self to an "ecology of war" produced through Crumb's music that renders these selves indistinct within this musical geography. The selves that inhabit Black Angels could be that of anybody in particular since Crumb seeks to invoke in his music the primeval experience of terror that inhabits in all of us as the inheritors of mankind's violence. This sense of the universal militates against the desirable qualities of popular music that rely on the production of autonomous and singular selves that make the distinction between enemy and friend possible and distinct. We focus on Crumb's use of archaisms, his construction of time in this piece, and the author's overall purpose to invoke a time of war rather than to reflect the conditions of war, in order to delineate the contours of the universal time and space producing the undifferentiated primeval self of war. We conclude that although Crumb's rejection of the national self deprives the piece of a salient place in the popular cannon of the war, it has left an intellectual legacy on the times of the Vietnam War that deserves to be preserved.
文摘Bread is still the most important food in Polish households. Staropolski and Pytlowy are two typical Polish breads, prepared with wheat and rye flour. The aim of this study was to examine the occurrence of volatile contaminants such as furan and its derivatives, and present a volatile profile of the most common furan derivatives in the described products. To measure concentration of chemical compounds such as furan and furan derivatives, fast and effective solid-phase micro-extraction/gas chromatography/mass spectrometry (SPME/GC/MS) methods were adapted. This study showed the differences in furan occurrence between Pytlowy and Staropolski, however, the greater differences were observed between different times and temperatures of baking rather than between the bread types. Clearly, the higher concentrations were found in products prepared during the longest baking time period of 50 min, and temperatures of 230 ℃ and 240 ℃. The highest furan level was detected in Staropolski 28.89 ± 1.16/μg/kg, baked for 50 min at 230 ℃ in bread crust. The volatile fraction of bread crust was composed of 5-9 furan derivatives while crumb layer contained only furan-2-pentyl. It was concluded that furan is present in almost each type of bread and percentage of furan derivatives in all volatile fractions ranged from 0.5 % to 60.6% in crust of examined bars.
基金supported by the Fundamental Research Funds for the Central Universities,China(lzujbky-2021-ey12)the National Natural Science Foundation of China(42072211)+1 种基金the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0602)the National Non-Profit Fundamental Research Grant of China(IGCEA 2008)。
文摘The incision of the Sanmen Gorge marks the birth of the modern Yellow River,but its timing varies from the late Miocene-early Pliocene to the late Pleistocene(~0.15 Ma),and the suggested forcing mechanisms vary from the uplift of the Tibetan Plateau to global climate change.Here,we report sedimentologic,geochronologic,and provenance data from a drill core near the Sanmen Gorge,the last gorge along the main course of the Yellow River.Our results indicate that typical river channel deposits,with detritus from the Ordos Block in the upstream regions,started to accumulate in the Sanmen Gorge at~1.25 Ma.When integrated with river terrace evidence from the upstream and downstream regions,the results provide robust evidence that the final integration of the modern Yellow River occurred at~1.25 Ma,consistent with the beginning of the Mid-Pleistocene transition(MPT).We propose that the accelerated lowering of eustatic sea level during the MPT may play as important a role as tectonism in driving the birth and evolution of the modern Yellow River.