Ceramics are strong but brittle. According to the classical theories, ceramics are brittle mainly because dislocations are suppressed by cracks. Here, the authors report the combined elastic and plastic deformation measurements of nanoceramics, in which dislocation-mediated stiff and ductile behaviors were detected at room temperature. In the synchrotron-based deformation experiments, a marked slope change is observed in the stress–strain relationship of MgAl2O4 nanoceramics at high pressures, indicating that a deformation mechanism shift occurs in the compression and that the nanoceramics sample is elastically stiffer than its bulk counterpart. The bulk-sized MgAl2O4 shows no texturing at pressures up to 37 GPa, which is compatible with the brittle behaviors of ceramics. Surprisingly, substantial texturing is seen in nanoceramic MgAl2O4 at pressures above 4 GPa. The observed stiffening and texturing indicate that dislocation-mediated mechanisms, usually suppressed in bulk-sized ceramics at low temperature, become operative in nanoceramics. This makes nanoceramics stiff and ductile.

A new helminthomorph millipede, Sinosoma luopingense new genus new species, from the Triassic Luoping biota of China, has 39 body segments, metazonites with lateral swellings that bear a pair of posterolateral pits (?insertion pits for spine bases), and sternites that are unfused to the pleurotergites. This millipede shares a number of characters with nematophoran diplopods, but lacks the prominent dorsal suture characteristic of that order. Other “millipede” material from the biota is more problematic. Millipedes are a rare part of the Luoping biota, which is composed mainly of marine and near-shore organisms. Occurrences of fossil millipedes are exceedingly rare in Triassic rocks worldwide, comprising specimens from Europe, Asia, and Africa, and consisting of juliform millipedes and millipedes that are either nematophorans or forms very similar to nematophorans.

Tiny, pelagic arthropods from the Anisian Luoping Biota exposed in two quarries near Luoping, Yunnan Province, China, represent the numerically most abundant organisms in the assemblage. They form the basis for definition of two, and possibly three, species referred to the order Lophogastrida, family Eucopiidae. Yunnanocopia grandis new genus new species and Y. longicauda n. gen. new species represent the oldest occurrence of mysidaceans in the fossil record. Their anatomy allies them with the Ladinian species Schimperella acanthocercus Taylor, Schram, and Shen, 2001, from Guizhou Province, China, which previously was thought to be the oldest lophogastrid, and with extant species of Eucopiidae. Their appearance in the Anisian represents one additional element of the early faunal radiation within the Luoping Biota following the end-Permian extinction event. Presence of well-preserved oostegites, along with other morphological features, documents a conservative bauplan expressed in Eucopiidae.

A large assemblage of small specimens of Tridactylastacus sinensis Feldmann, Schweitzer, and Zhang in Feldmann et al., 2012, from the Middle Triassic (Anisian) Luoping Biota, Yunnan Province, China, permitted cladistic analysis confirming their placement within Litogastridae in the superfamily Glypheoidea. Orientation of 86 specimens closely spaced on a single slab from one bedding surface revealed a preferred orientation suggestive of mild current activity. The specimens were interpreted to have been victims of a mass kill, possibly an algal bloom, within the water column.

A large collection of macrurous decapod crustaceans is recorded from the middle–late Anisian (Middle Triassic) Guanling Formation in Yunnan Province, China. A remarkable assemblage of over 20,000 vertebrate, invertebrate, and plant fossils collectively referred to as the Luoping Biota has been collected from quarries in the vicinity of the city of Luoping. Among these, arthropods including the decapods are the most common element although articulated fish and reptiles are also common. The decapods represent new taxa, including Koryncheiros luopingensis n. gen. n. sp. within Clytiopsidae, a newly elevated family within Erymoidea; Tridactylastacus sinensis n. gen. n. sp. within Glypheidae; and Yunnanopalinura schrami n. gen. n. sp. within Palinuridae. A single specimen has been referred to Palinuridae sp. Koryncheiros luopingensis exhibits a unique cheliped architecture and the second through fourth chelipeds are subchelate, an extremely rare configuration. Tridactylastacus sinensis also exhibits subchelate closures of pereiopods 2–4, but it bears a distinctive subchelate first pereiopod with an intercalated spine between the fingers on the distal margin of the propodus. Yunnanopalinura schrami represents the oldest occurrence of Palinuridae and Achelata. Collectively, these expand our knowledge of Chinese decapods significantly in that only six species of fossil decapods have been described previously from the country.

The distribution of all recognized biotic elements was mapped on five extensive surfaces of the Middle Triassic Guanling Formation exposed in quarries near Luoping, Yunnan Province, China. A 0.5 m2 grid was overlain on the surfaces, and all recognizable fossils were located by placing them in one of nine quadrants within the grid. A total of 240 m2 were mapped, and each specimen observed was recorded as one of 15 categories, subsequently grouped as pelagic, benthic, and other (bone, trace fossils, algae). The pelagic component, fish, thylacocephalans, and mysidaceans, dominated all layers. The benthic component was sparse on all surfaces; epifaunal, vagrant organisms were the dominant forms, suggesting that the substrate was unsuitable for infaunal and sessile epifaunal organisms. Shrimp and bivalves dominated the benthic organisms. Two of the surfaces were overwhelmingly dominated by mysidaceans, and one was dominated by thylacocephalans, suggesting that their remains documented periodic mass kills of swarming, pelagic organisms. Scanning electron microscope analysis of the bedding surfaces revealed nothing remarkable about the sediment, suggesting that the cause of death of the organisms was likely due to an event within the water column, possibly an algae bloom, not recorded in the sediment record.

Two new genera, Anisaeger and Distaeger, and three new species, Anisaeger brevirostrus, A. spiniferus, and Distaeger prodigiosus, extend the range of the Aegeridae (Dendrobranchiata, Penaeoidea) into the Middle Triassic (Anisian) of China. Seven decapod crustacean species are now known from the Luoping biota of southern China. Morphological features of shrimp that are present but rarely mentioned in the neontological literature are recognized as potentially useful in classifying fossil material, including a diaeresis on the exopod of the uropods and multiarticulate flagellae on pleopods. Unusual taphonomic features of the shrimp include fractured cuticle, preservation in lateral, dorsal, and ventral position, and twisted cephalothoraxes.

A new penaeoid shrimp collected from the Middle Triassic Member II of the Guanling Formation in the vicinity of the city of Luxi, Yunnan, southwest China, is a new species, Aeger luxii n. sp. The new species possesses prominent spinose third maxillipeds, which is one of the typical characteristics of Aeger. The new species differs from the type species, Aeger tipularius from the Jurassic Solnhofen Plattenkalk, in having a long, smooth rostrum with no subrostral spines. The new taxon increases the diversity of Chinese decapods, and further expands our knowledge of the phylogeny and evolution of the Mesozoic decapods. The find is the first complete specimen of Aeger in the Middle Triassic, and reveals a close biogeographic connection of the marine ecosystem between Eastern and Western Tethys.

This paper summarizes the work we conducted in recent years on modeling plastic response of metallic alloys and ductile fracture of engineering components, with the emphasis on the effect of the stress state. It is shown that the classical J2 plasticity theory cannot correctly describe the plasticity behavior of many materials. The experimental and numerical studies of a variety of structural alloys result in a general form of plasticity model for isotropic materials, where the yield function and the flow potential are expressed as functions of the first invariant of the stress tensor and the second and third invariants of the deviatoric stress tensor. Several mechanism-based models have been developed to capture the ductile fracture process of metallic alloys. Two of such models are described in this paper. The first one is a cumulative strain damage model where the damage parameter is dependent on the stress triaxiality and the Lode parameter. The second one is a modification to the Gurson-type porous plasticity models, where two damage parameters, representing void damage and shear damage respectively, are coupled into the yield function and flow potential. These models are shown to be able to predict fracture initiation and propagation in various specimens experiencing a wide range of stress states.

Hafnium dioxide (HfO2) thin films were synthesized on silicon and quartz substrates by thermal oxidation of metallic hafnium films in oxygen. The crystalline structure and optical properties of the HfO2 films were systematically investigated using x-ray diffraction, ultraviolet (UV)-Raman, and UV-visible spectrophotometer techniques. All the films thermally oxidized at 450 to 800 °C were mostly monoclinic. Interestingly, cubic phase coexisted with monoclinic phase in the films thermally oxidized at 500 to 600 °C. The corresponding optical band gap (Eg) varied from 5.92 to 6.08 eV for the films with a different phase ratio (cubic to monoclinic one) ranging between 0 and 1:3. These results imply that the mixed phase could have a certain effect on the increase of the Eg of HfO2 films.

Thornlike Tb-doped SiC (SiC:Tb) nanostructures were synthesized through a carbothermal reduction of electrospun Tb-doped SiO2 nanofibers (SiO2:Tb). The synthesized SiC nanostructures annealed at a high temperature of 1300 °C displayed a unique morphology and a high crystalline quality with the β-SiC phase. Strong green-light emissions were detected from the SiC:Tb samples. Photoluminescence excitation results show that, besides a small amount of energy coming from the SiC cores (464 nm), most of the energy needed for the excitation of Tb3+ ions comes from the light absorption of the SiO2–Tb surface layers (295 nm) and near-interface regions in the samples (388 nm). Transmission electron microscopy, energy dispersive spectrometry, and Raman analyses suggested that the formations of Tb clusters and SiO2 surface layers are very important to the enhancement of the luminescence behaviors of Tb3+ ions. Finally, we have constructed an excitation model and further proposed an energy transfer mechanism for these thornlike SiC:Tb nanostructures.