I report on the occurrence of a pair of novel and related post-sedimentary structures that form in the Neogene cross</span><span style="font-family:Verdana;">-</span><span style="fo...I report on the occurrence of a pair of novel and related post-sedimentary structures that form in the Neogene cross</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">bedded red sandstones in the As-Subbiyah area, north of Kuwait Bay, Kuwait. I named them barrellite and pillarrite. Barrellite forms as vertical tubes of concentric sheaths of siltstone with partially hollow interior or intervening homogeneous and structure-less sandstone. It stands as barrels above the background sandstone. Pillarrite forms as discrete, vertical and solitary spines of homogeneous sandstone and siltstone, or inside barrellite masses from which successive siltstone sheaths were stripped. The structures range in diameter from one-centimeter poke marks to one-meter-wide barrels and hunks, and their vertical length exceeds two meters. Barrellite, pillarrite and their complex intergrowths develop near thin quartz veins and chaotic zones, and form with them complex geometrical relationships. The dual structures are genetically related and fall within the general class of tubular structures in sedimentary rocks. I consider them as a special type of sand injectites.</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">The mode of formation of these structures is enigmatic. They develop in a geological setting that displays evidence of a widespread and vigorous oil field brine. I suggest a tentative scenario for their </span><span style="font-family:Verdana;">formation, involving flushing of the brine through hydraulic fracturing of the sedimentary succession above the Ebharah Oil Field reservoir in the As-Subbiyah area. The brine plucks mineral and rock fragments and mixes</span><span style="font-family:Verdana;"> with them along its paths, producing a heterogeneous slurry. Ultimately, the slurry solidifies as barrellite and pillarrite, chaotic zones and quartz veins. The vertical nature of the structures, circular and internal concentric arrangements, as well as the homogenous lithology inside their masses mimic characteristics of flow and deposits in vertical and horizontal pipelines.展开更多
Semiconductor materials with heterogeneous interfaces and twin structures generally demonstrate a higher concentration of carriers and better electrical stability.A variety of Cu-doped Co_(0.98)Cu_(x)Mn_(2.02−x)O_(4)(...Semiconductor materials with heterogeneous interfaces and twin structures generally demonstrate a higher concentration of carriers and better electrical stability.A variety of Cu-doped Co_(0.98)Cu_(x)Mn_(2.02−x)O_(4)(0≤x≤0.5)negative temperature coefficient(NTC)ceramics with dual phases and twin structures were successfully prepared in this study.Rietveld refinement indicates that the content of a cubic spinel phase increases with increasing Cu content.The addition of Cu can promote grain growth and densification.Atomic-level structural characterization reveals the evolution of twin morphology from large lamellae with internal fine lamellae(LIT lamellae)to large lamellae without internal fine lamellae(L lamellae)and the distribution of twin boundary defects.First-principles calculations reveal that the dual phases and twin structures have lower oxygen-vacancy formation energy than those in the case of the pure tetragonal and cubic spinel,thereby enhancing the transmission of carriers.Additionally,the three-dimensional charge-density difference shows that metal ions at the interface lose electrons and dwell in high valence states,thereby enhancing electrical stability of the NTC ceramics.Furthermore,the additional Cu ions engage in electron-exchange interactions with Mn and Co ions,thereby reducing resistivity.In comparison to previous Cu-containing systems,the Co_(0.98)Cu_(x)Mn_(2.02−x)O_(4)series exhibit superior stability(aging value≤2.84%),tunable room-temperature resistivity(ρ),and material constant(B)value(17.5Ω·cm≤ρ≤7325Ω·cm,2836 K≤B≤4315 K).These discoveries lay a foundation for designing and developing new NTC ceramics with ultra-high performance.展开更多
Effect of {10-12} twins on the mechanical properties of magnesium alloy has received considerable research interest. A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation with the aim of introd...Effect of {10-12} twins on the mechanical properties of magnesium alloy has received considerable research interest. A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation with the aim of introducing {10-12} twin lamellar structure. It has been found that higher strength and better ductility are obtained when tensile loading is perpendicular to the c axis of twin region of the twin lamellar structured sample, indicating that the plasticity improvement caused by twins depends on the special strain path. The fracture morphology of the twin lamellar structured sample shows a dimple fracture mode under tensile loading perpendicular to the c axis, while the cleavage fracture with river pattern has been observed in other fractured samples. Above experimental results indicate that the interaction of dislocations and twin lamellae may play an important role in improving mechanical properties of Mg alloy.展开更多
Reaction of dimers of (R) thionophosphine sulfide (R = P - C6H4OMe,SMe ) with Co, (CO), yields the novel hexacobalt cluster [Co'(μ3, -S)2, (CO) 14 (μ4 -μ4- and the trinuclear clusterPSCH,)J 2' In 1, tw0 Co3...Reaction of dimers of (R) thionophosphine sulfide (R = P - C6H4OMe,SMe ) with Co, (CO), yields the novel hexacobalt cluster [Co'(μ3, -S)2, (CO) 14 (μ4 -μ4- and the trinuclear clusterPSCH,)J 2' In 1, tw0 Co3S(C0)7 units linked by a novel phosphido-thio1ato bifunc-tiona1 bridging p'-SPR ligand as backbone.展开更多
The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of st...The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of strain induced a2/γinterfaces and two types of strain induced twin boundaries were identified The most,important features are high density of ledges and the existence of I/3[111] Frank partial dislocation. Mechanisms for the formation these interfaces were proposed Two types of deformation twins were observed These deformation twins always start from the ledges it seems that ledges at interfaces are important features of interfacial structure for the mechanical behavior of alloys.展开更多
The α alloy Ti-2Al-2.5Zr and near α alloy Ti-4Al-2V were hydrogenated to various levels. The morphology, orientation relation （OR）, and habit plane of the hydrides were studied by means of transmission electron mi...The α alloy Ti-2Al-2.5Zr and near α alloy Ti-4Al-2V were hydrogenated to various levels. The morphology, orientation relation （OR）, and habit plane of the hydrides were studied by means of transmission electron microscopy （TEM）. It was found that in the two alloys most of the precipitates are δ-hydrides which have fcc structure with the lattice parameter a = 0.44 nm. Two basic orientation relationships and habit planes of the precipitates are determined. Twin structure was observed in both alloys.展开更多
High-quality Bi2Se3 microcrystals were grown by the physical vapor transport （PVT） method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well facete...High-quality Bi2Se3 microcrystals were grown by the physical vapor transport （PVT） method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well faceted and have dimensions up to -200 μm, The growth proceeds by the layer-by-layer mecha- nism with the formation of flat low-growth rate facets. The phase composition of the grown crystals was identified by the X-ray single crystal structure analysis in space group R3m, a = 4.1356（3）, C= 28.634（5）A, Z=3 （R=0.0147）. The most probable twin planes in the tetradymite structure were evaluated by the pseudo translational sublattice merhad.展开更多
文摘I report on the occurrence of a pair of novel and related post-sedimentary structures that form in the Neogene cross</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">bedded red sandstones in the As-Subbiyah area, north of Kuwait Bay, Kuwait. I named them barrellite and pillarrite. Barrellite forms as vertical tubes of concentric sheaths of siltstone with partially hollow interior or intervening homogeneous and structure-less sandstone. It stands as barrels above the background sandstone. Pillarrite forms as discrete, vertical and solitary spines of homogeneous sandstone and siltstone, or inside barrellite masses from which successive siltstone sheaths were stripped. The structures range in diameter from one-centimeter poke marks to one-meter-wide barrels and hunks, and their vertical length exceeds two meters. Barrellite, pillarrite and their complex intergrowths develop near thin quartz veins and chaotic zones, and form with them complex geometrical relationships. The dual structures are genetically related and fall within the general class of tubular structures in sedimentary rocks. I consider them as a special type of sand injectites.</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">The mode of formation of these structures is enigmatic. They develop in a geological setting that displays evidence of a widespread and vigorous oil field brine. I suggest a tentative scenario for their </span><span style="font-family:Verdana;">formation, involving flushing of the brine through hydraulic fracturing of the sedimentary succession above the Ebharah Oil Field reservoir in the As-Subbiyah area. The brine plucks mineral and rock fragments and mixes</span><span style="font-family:Verdana;"> with them along its paths, producing a heterogeneous slurry. Ultimately, the slurry solidifies as barrellite and pillarrite, chaotic zones and quartz veins. The vertical nature of the structures, circular and internal concentric arrangements, as well as the homogenous lithology inside their masses mimic characteristics of flow and deposits in vertical and horizontal pipelines.
基金supported by the National Natural Science Foundation of China(Grant No.52002347)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.19KJB430039).
文摘Semiconductor materials with heterogeneous interfaces and twin structures generally demonstrate a higher concentration of carriers and better electrical stability.A variety of Cu-doped Co_(0.98)Cu_(x)Mn_(2.02−x)O_(4)(0≤x≤0.5)negative temperature coefficient(NTC)ceramics with dual phases and twin structures were successfully prepared in this study.Rietveld refinement indicates that the content of a cubic spinel phase increases with increasing Cu content.The addition of Cu can promote grain growth and densification.Atomic-level structural characterization reveals the evolution of twin morphology from large lamellae with internal fine lamellae(LIT lamellae)to large lamellae without internal fine lamellae(L lamellae)and the distribution of twin boundary defects.First-principles calculations reveal that the dual phases and twin structures have lower oxygen-vacancy formation energy than those in the case of the pure tetragonal and cubic spinel,thereby enhancing the transmission of carriers.Additionally,the three-dimensional charge-density difference shows that metal ions at the interface lose electrons and dwell in high valence states,thereby enhancing electrical stability of the NTC ceramics.Furthermore,the additional Cu ions engage in electron-exchange interactions with Mn and Co ions,thereby reducing resistivity.In comparison to previous Cu-containing systems,the Co_(0.98)Cu_(x)Mn_(2.02−x)O_(4)series exhibit superior stability(aging value≤2.84%),tunable room-temperature resistivity(ρ),and material constant(B)value(17.5Ω·cm≤ρ≤7325Ω·cm,2836 K≤B≤4315 K).These discoveries lay a foundation for designing and developing new NTC ceramics with ultra-high performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.51071183,50890170 and 51271208)Basic Research of China(No.2010CB631004)Fundamental Research Funds for the Central Universities(No.CDJXS11132225)
文摘Effect of {10-12} twins on the mechanical properties of magnesium alloy has received considerable research interest. A hot-rolled AZ31 Mg alloy sheet was subjected to dynamic plastic deformation with the aim of introducing {10-12} twin lamellar structure. It has been found that higher strength and better ductility are obtained when tensile loading is perpendicular to the c axis of twin region of the twin lamellar structured sample, indicating that the plasticity improvement caused by twins depends on the special strain path. The fracture morphology of the twin lamellar structured sample shows a dimple fracture mode under tensile loading perpendicular to the c axis, while the cleavage fracture with river pattern has been observed in other fractured samples. Above experimental results indicate that the interaction of dislocations and twin lamellae may play an important role in improving mechanical properties of Mg alloy.
文摘Reaction of dimers of (R) thionophosphine sulfide (R = P - C6H4OMe,SMe ) with Co, (CO), yields the novel hexacobalt cluster [Co'(μ3, -S)2, (CO) 14 (μ4 -μ4- and the trinuclear clusterPSCH,)J 2' In 1, tw0 Co3S(C0)7 units linked by a novel phosphido-thio1ato bifunc-tiona1 bridging p'-SPR ligand as backbone.
基金This project was financially supported by the National Science Foundation of Chongqing(Project no.cstc2018jcyjAX0070)Fundamental Research Funds for the Central Universities(Project No.XDJK2019B003)+1 种基金the National Natural Science Foundation of China(Project no.51601154)The authors are also very grateful to Yanan Chen and Zhiwen Du for checking the language.
文摘The structure characteristics of a2/γinterfaces and the features of deformation twins in a quasi-isothermal forged Ti-45Al-10Nb alloy were studied by highresolution transmission electron microscopy. Three types of strain induced a2/γinterfaces and two types of strain induced twin boundaries were identified The most,important features are high density of ledges and the existence of I/3[111] Frank partial dislocation. Mechanisms for the formation these interfaces were proposed Two types of deformation twins were observed These deformation twins always start from the ledges it seems that ledges at interfaces are important features of interfacial structure for the mechanical behavior of alloys.
文摘The α alloy Ti-2Al-2.5Zr and near α alloy Ti-4Al-2V were hydrogenated to various levels. The morphology, orientation relation （OR）, and habit plane of the hydrides were studied by means of transmission electron microscopy （TEM）. It was found that in the two alloys most of the precipitates are δ-hydrides which have fcc structure with the lattice parameter a = 0.44 nm. Two basic orientation relationships and habit planes of the precipitates are determined. Twin structure was observed in both alloys.
文摘High-quality Bi2Se3 microcrystals were grown by the physical vapor transport （PVT） method without using a foreign transport agent. The microplate crystals grown under the optimal temperature gradient are well faceted and have dimensions up to -200 μm, The growth proceeds by the layer-by-layer mecha- nism with the formation of flat low-growth rate facets. The phase composition of the grown crystals was identified by the X-ray single crystal structure analysis in space group R3m, a = 4.1356（3）, C= 28.634（5）A, Z=3 （R=0.0147）. The most probable twin planes in the tetradymite structure were evaluated by the pseudo translational sublattice merhad.
