The Silurian and Devonian plant fossil record is the basis for our understanding of the early evolution of land plants, yet our appreciation of early global phytogeographic evolution has been constrained by the focus of most studies on deposits from Europe, North America, and, more recently, South China. Devonian plants have been recorded rarely from northeastern China, and among previous records, few plants have been illustrated and formally described. In this article, megafossil plants representing a Late Devonian-aged (probably Famennian) flora are described from a locality at northern Sonid Zuoqi, Inner Mongolia, NE China. The flora includes Melvillipteris sonidia new species, Archaeopteris sp., and fragments of some other plants. The new plant shows main axes and two orders of lateral branches. The first-order branches of this plant show a typical zigzag appearance and are borne in pairs on main axes. Second-order branches are straight or slightly flexed, and are borne helically or alternately on first-order branches. Sterile ultimate appendages and fertile structures of M. sonidia n. sp. are borne alternately on second-order branches. An associated palynological assemblage, as well as U-Pb ages of detrital zircon grains from adjacent horizons, are also reported, indicating a Late Devonian age in accord with the megafossil plants. The present study contributes to our appreciation of the Devonian floristic diversity of the Xing'an Block, and, through our review of the record of early vascular plants from NE China, more broadly to the understanding of the mid-latitude vegetation of the Northern Hemisphere during the Late Devonian.

Carbon nanotube foams (CNFs) have been successfully used as near-critical-density targets in the laser-driven acceleration of high-energy ions and electrons. Here we report the recent advances in the fabrication technique of such targets. With the further developed floating catalyst chemical vapor deposition (FCCVD) method, large-area ($>25\kern0.5em {\mathrm{cm}}^2$) and highly uniform CNFs are successfully deposited on nanometer-thin metal or plastic foils as double-layer targets. The density and thickness of the CNF can be controlled in the range of $1{-}13\kern0.5em \mathrm{mg}/{\mathrm{cm}}^3$ and $10{-}200\kern0.5em \mu \mathrm{m}$, respectively, by varying the synthesis parameters. The dependence of the target properties on the synthesis parameters and the details of the target characterization methods are presented for the first time.

Single-shot laser-induced damage threshold (LIDT) measurements of multi-type free-standing ultrathin foils were performed in a vacuum environment for 800 nm laser pulses with durations τ ranging from 50 fs to 200 ps. The results show that the laser damage threshold fluences (DTFs) of the ultrathin foils are significantly lower than those of corresponding bulk materials. Wide band gap dielectric targets such as SiN and formvar have larger DTFs than semiconductive and conductive targets by 1–3 orders of magnitude depending on the pulse duration. The damage mechanisms for different types of targets are studied. Based on the measurement, the constrain of the LIDTs on the laser contrast is discussed.

New occurrences of middle–late Darriwilian (Middle Ordovician) conodonts are reported from the Nyalam region, southern Tibet. The conodont-yielding strata, referred to the Chiatsun Group, accumulated on the north Indian continental margin of northern Gondwana. These Middle Ordovician conodonts include the informal species Histiodella sp. A in the middle part of the Lower Formation of the Chiatsun Group succeeded by a fauna of the Pygodus serra Zone in the upper part of that formation. Pygodus anserinus is recorded from the base of the Upper Formation of the Chiatsun Group. The Nyalam succession and its conodont taxa allow for precise correlation of the strata preserved on top of Mount Qomolangma (Mount Everest), eastern Tibet and the Peri-Gondwana Lhasa (north central Tibet), South China, North China, Tarim Basin and Thailand-Malaysia (Sibumasu Terrane) terranes and/or microcontinents. The middle Darriwilian positive increase in δ13Ccarb values (carbon isotope excursion, or MDICE) is recorded from most terranes, and can be related to a late middle Darriwilian global short-term cooling and sea-level drop. The cooling event prompted temperate- to warm-water taxa to migrate towards the palaeoequator and constrained the Australasian Province to locations near and at the palaeoequator. The intensified oceanic circulation and upwelling on continental margins probably caused some characteristic taxa to become extinct. The incoming fauna was mainly of cool-water taxa. The conodont specimens from southern Tibet are black to pale grey, corresponding to conodont colour index (CAI) values of 5 to 6, which demonstrates that the host sedimentary rocks were once heated to more than 360°C.

In this study, we investigated the elastic constants, moduli, hardness, and electronic structures of Ti–Al intermetallic compounds (TiAl, Ti3Al, and TiAl3) using first-principles calculations. The cohesive energy and formation enthalpy of these compounds are negative, which indicates that they are thermodynamically stable. We calculated the elastic constants and moduli using the stress–strain method and Voigt–Reuss–Hill approximation, respectively. We evaluated the mechanical anisotropy of these compounds using the anisotropic index and found that the results are in good agreement with other experimental and theoretical data. We evaluated the chemical bonding of these compounds by calculating their density of states, the results of which revealed that the bonding behavior of all Ti–Al intermetallic compounds involved a mixture of metallic and covalent bonds. We also estimated the Debye temperature and sound velocities of these Ti–Al intermetallic compounds.

The purpose of this paper was to study the interaction effects of rainfall regime and slope length on runoff and soil loss under different land uses. Event runoff and soil loss in forest, shrub and grass were measured in plots with lengths of 5, 9 and 13m in the Loess Plateau from 2008 to 2016. A total of 59 erosive rainfall events were recorded and classified into three rainfall regimes. Firstly, the results showed that the runoff coefficient was grass>shrub>forest, and soil loss was grass>forest>shrub, but the differences between forest and shrub in runoff and between grass and forest in soil loss did not reach significant levels. Secondly, rainfall regimes had an important effect on runoff and soil loss under different land uses. The lowest runoff coefficients and the highest soil loss in regime 2 were found in shrub and forest land, respectively, which differed from that of regime 1. In total, rainfall regime 1 had the highest runoff coefficient of 0.84–2.06%, followed by regime 3 with 0.33–0.88% and regime 2 with 0.04–0.06%. Soil loss in forest and grass land had a different order of regime 3>regime 1>regime 2. Thirdly, both the runoff coefficient and soil loss decreased with increasing plot length, while the effect of slope length on runoff/soil loss were influenced by land use type and rainfall regimes.

A study was conducted to examine the effects of residence time and temperature on atrazine extractability and degradation in a sediment generated from Emporia sandy loam soil submerged under a water column. Sediments amended with 2.8 μg of atrazine were incubated at two temperatures (5 and 24 C), sampled at 0, 14, 28, 112, 168, 252, and 336 d, and then sequentially extracted once with 80 ml 0.01 M CaCl2 aqueous solution, three times with 25 ml of methanol/water mixture (4:1, v/v), and three times with 25 ml of methanol/water/formic acid (20:5:1, v/v pH 3.2) for a total of seven times. Extracts were analyzed for atrazine and metabolites using reverse phase high-performance liquid chromatography. The rate of bound residue formation was greater at 24 than at 5 C. About 30 and 60% of the 14C was bound (nonextractable) to sediments at 5 and 24 C, respectively. Water was less effective in extracting 14C residues from sediments incubated at 24 C than at 5 C. Acidification of the methanol/water mixture with formic acid during the last extraction step improved the removal of hydroxyatrazine from sediment. Atrazine degraded primarily to hydroxyatrazine (HA) and to a lesser extent to deethylatrazine (DEA). Although no DEA was found, HA at 43 μg kg−1 of sediment was detected 112 d after treatment at 5 C, indicating that chemical degradation could occur at a low temperature if sediments are incubated for extended periods of time. At 24 C, HA was found within 28 d and reached the maximum level at day 252. The results suggested that HA is the major metabolite of atrazine in the sediment; a significant fraction of the residue was unavailable for extraction, and this unextractable portion increased with residence time.

The genus Sphenothallus was erected by Hall (1847, p. 261), who originally considered it a land plant. Sphenothallus was later classified as a marine invertebrate. Moore and Harrington (1956, p. F65) regarded Sphenothallus as a hydrozoan or scyphozoan. Van Iten et al. (1992, p. 139) supported Moore and Harrington's idea, and argued that it displays a close relationship to conularids (also see Li, 2000, p. 91). However, Mason and Yochelson (1985, p. 93–94) suggested that Sphenothallus is an annelid or “worm” (also see Fauchald et al., 1986, p. 64; Feldmann et al., 1986, p. 344–345; Choi, 1990, p. 403; Bartels et al., 1998, p. 114–117). The exact phylogenetic affinity of Sphenothallus is still debated.

Upper Neoproterozoic successions in the North China and nearby Chaidam blocks are poorly documented. North China successions typically consist of a diamictite unit overlain by siltstone, sandstone, or slate. Similar successions occur in Chaidam, although a cap carbonate lies atop the diamictite unit. The diamictites in both blocks have been variously interpreted as Cryogenian, Ediacaran, or Cambrian glacial deposits. In this paper, we describe problematic macrofossils collected from slate of the upper Zhengmuguan Formation in North China and sandstone of the Zhoujieshan Formation in Chaidam; both fossiliferous formations conformably overlie the aforementioned diamictites. Some of these fossils were previously interpreted as animal traces. Our study recognizes four genera and five species—Helanoichnus helanensis Yang in Yang and Zheng, 1985, Palaeopascichnus minimus n. sp., Palaeopascichnus meniscatus n. sp., Horodyskia moniliformis? Yochelson and Fedonkin, 2000, and Shaanxilithes cf. ningqiangensis Xing et al., 1984. None of these taxa can be interpreted as animal traces. Instead, they are problematic body fossils of unresolved phylogenetic affinities. The fundamental bodyplan similarity between Horodyskia and Palaeopascichnus, both with serially repeated elements, indicates a possible phylogenetic relationship. Thus, at least some Ediacaran organisms may have a deep root because Horodyskia also occurs in Mesoproterozoic successions.

Among the four genera reported here, Palaeopascichnus Palij, 1976 and Shaanxilithes Xing et al., 1984 have been known elsewhere in upper Ediacaran successions, including the Dengying Formation (551-542 Ma) in South China. If these two genera have biostratigraphic significance, the fossiliferous units in North China and Chaidam may be upper Ediacaran as well. Thus, the underlying diamictites in North China and Chaidam cannot be of Cambrian age, although their correlation with Ediacaran and Cryogenian glaciations remains unclear. As no other Neoproterozoic diamictite intervals are known in North China and Chaidam, perhaps only one Neoproterozoic glaciation is recorded in that area.

This paper presents biped walking control using a library of optimal trajectories. Biped walking control is formulated as an optimal control problem. We use a parametric trajectory optimization method to find the periodic steady-state walking trajectory. As a second stage, we use Differential Dynamic Programming to generate a library of optimal trajectories and locally linear models of the optimal control law, which are used to construct a more global control law. The proposed controller is compared with a trajectory tracking controller using optimal gains. The utility and performance of the proposed method are evaluated using simulated walking control of a planar five-link biped robot.

The objective of the study was to evaluate the relationship of veterinary clinical assessments of lameness to probability estimates of lameness predicted from vertical kinetic measures. We hypothesized that algorithm-derived probability estimates of lameness would accurately reflect vertical measures in lame limbs even though vertical changes may not inevitably occur in all lameness. Kinetic data were collected from sound (n=179) and unilaterally lame (n=167) dairy cattle with a 1-dimensional, parallel force plate system that registered vertical ground reaction force signatures of all four limbs as cows freely exited the milking parlour. Locomotion was scored for each hind limb using a 1–5 locomotion score system (1=sound, 5=severely lame). Pain response in the interdigital space was quantified with an algometer and pain response in the claw was quantified with a hoof tester fitted with a pressure gage. Lesions were assigned severity scores (1=minimal pathology to 5=severe pathology). Lameness diminished the magnitude of peak ground reaction forces, average ground reaction forces, Fourier transformed ground reaction forces, stance times and vertical impulses in the lame limbs of unilaterally lame cows. The only effect of lameness on the opposite sound limb was increased magnitude of stance times and vertical impulses in unilaterally lame cows. Symmetry measures of the peak ground reaction forces, average ground reaction forces, Fourier transformed ground reaction forces, stance times and vertical impulses between the left and right hind limbs were also affected in unilateral lameness. Paradoxically, limbs with clinically similar lesion and locomotion scores and pain responses were associated with a broad range of load-transfer off the limb. Substantial unloading and changes in the vertical limb variables occurred in some lameness while minimal unloading and changes in vertical limb variables occurred in other lameness. Corresponding probability estimates of lameness accurately reflected changes in the vertical parameters of limbs and generated low probability estimates of lameness when minimal unloading occurred. Failure to transfer load off limbs with pain reactions, locomotion abnormalities and lesions explained much of the limited sensitivity in lameness detection with vertical limb variables.

To clarify some discrepancies in the literature about the formation of icosahedral quasi-crystal (IQC) in Al–Cu–Fe alloys, microstructures, and constituent phases of Al62.5Cu25Fe12.5 and Al65Cu20Fe15 alloys were studied. Each dendritic arm of the primarily solidified λ–Al13Fe4 phase is a single crystal that possesses no definite orientation relationship with the IQC, formed by peritectic reaction (L + λ + β → IQC) or a solid-state reaction (Cu-rich phases + λ + β →?IQC). This fact disproves an assumption that λ-phase is an approximant of the IQC. Two types of cubic phase, β-phase with CsCl structure containing more Fe and τ3 phase, which is a superstructure and contains less Fe, were observed depending on the composition and thermal history of the samples.

We report here our preliminary results on orientation determination and phase identification using the electron backscatter diffraction (EBSD) technique. Using a scanning electron microscope (SEM) equipped with the EBSD attachment. it is now possible to study the correspondence and orientation relationships of parent-phase and martensite variants in shape memory alloys (SMAs). Previously, such an information was obtained from large single crystals studied by micro-beam X-ray Laue diffraction and supplemented by transmission electron microscopy study of thin foils. Figs. 1(a), (b) and (c) are three EBSD patterns taken from neighboring areas in a Cu-12.55Al-4.86Ni (wt%) SMA. Computer simulation reveals that Fig. 1(a) belongs to the parent-phase of D03-structure type, and Figs. 1(b) and (c) belong to variants A and D of 2H martensite, respectively. Corresponding simulated EBSD patterns are shown in Figs. 1(d), (e) and (f). Fig. 1 indicates that the (0 0 2)A basal plane of the martensite variant A is transformed from the (-2-2 0)p plane of the parent-phase and its [0-1 0]A direction from the [0 0 1]P direction. The (0 0 2)D basal plane of the martensite variant D is transformed from the (2-2 0)P plane of the parent-phase and its [0 1 0 ]D direction from the [0 0 1]P direction.