A rare lobopod with well-preserved eyes from Chengjiang Lagerstātte and its implications for origin of arthropods

The origin of arthropods has long been one ofthe most hotly-debated subjects. Arthropods used to bethought closely related with annelids, but the two groups arenow believed to be separated into two major realms withinProtostomia on the basis of new molecular data. Although itis generally held by paleontologists that arthropods should berooted in the early lobopods-.a kind of worm-like creaturewith non-segmented legs, no intermediate forms have beenfound to bridge them. Here we report an organism with amixture of characters, including features characteristic ofarthropods (e.g., primary cephalization with paired eyes,paired antennae, and preliminary tagmosis) and of lobopods(e.g., worm-like body design, the dorsal spines, andnon-segmented limbs or lobe-like legs). The discovery of therare transitional form may throw new light on the origin ofarthropods and suggests that the most primitive arthropodsbegan with paired uniramous legs and the biramous onesevolved later.     

A Cambrian micro-lobopodian and the evolution of arthropod locomotion and reproduction

The evolutionary success of arthropods, the most abundant and diverse animal group, is mainly based on their segmented body and jointed appendages, features that had evolved most likely already before the Cambrian. The first arthropod-like animals, the lobopodians from the Early Cambrian, were unsclerotized and worm-like, and they had unjointed tubular legs. Here we describe the first three-dimensionally preserved Cambrian lobopodian. The material presented of Orstenotubulus evamuellerae gen. et sp. nov. is the smallest and youngest of a lobopodian known. O. evamuellerae shows strikingly detailed similarities to Recent tardigrades and/or onychophorans in its cellular-structured cuticle and the telescopic spines. It also shows similarities to other, longer known lobopodians, but which are ten times as large as the new form. These similarities include the finely annulated body and legs, which is characteristic also for Recent onychophorans, and paired humps continuing into spines situated dorsally to the leg insertions, a feature lacking in the extant forms. The morphology of O. evamuellerae not only elucidates our knowledge about lobopodians, but also aids in a clearer picture of the early evolution of arthropods. An example is the single ventral gonopore between a limb pair of O. evamuellerae, which indicates that a single gonopore, as developed in onychophorans, tardigrades, pentastomids, myriapods and insects, might represent the plesiomorphic state for Arthropoda, while the paired state in chelicerates and crustaceans was convergently achieved. Concerning life habits, the lateral orientation of the limbs and their anchoring spines of the new lobopodian imply that early arthropods were crawlers rather than walkers.     

Progress and significance in research on the early Middle Cambrian Kaili Biota, Guizhou Province,China

Important progress in research on the Kaili Biota has been made recently. Many interesting components from Chengjiang Biota and Burgess Shale Biota have been discovered, e.g. Microdictyon of lobopodia; Ottoia, Palaeoscolex of worms; Naraoia, Marrella of Trilobitioidea, Mollisonia, anamalocarids and other non-trilobite arthropods; and new sorts of echinoder-mas, macroalage fossils and so on. Recent work on the Kaili Biota has resulted in the following developments: (i) an increase in the number of animal genera, up to more than 100 genera in total, so that the Kaili Biota has become the third most diverse of the Burgess Shale-type Biota after the Burgess Shale and Chengjiang Biotas; and (ii) the most noteworthy fossils in the Kaili Biota are echinoderms, non-trilobite arthropods and soft-bodied medusiform fossils, especially the most diverse echinoderms. The progress provides envidence for the biodiversity of marine organisms presented after the "Cambrian Explosion" and serves as a link between the earlist Cambrian Chengjiang Biota and late early Middle Cambrian Burgess Shale Biota. It is of great significance in the reconstruction of the Cambrian palaeoplate, palaeongeography and in research on taphonomy.     

New observations of the lobopod-like worm Facivermis from the Early Cambrian Chengjiang Lagersttte

Facivermis yunnanicus （Hou ＆ Chen, 1989）, from the Early Cambrian Chengjiang Lagerstatte, a worm-like fossil with 5 pairs of tentacles and a perceived shrunken end, has been regarded as related to polychaetes, later it has been variously interpreted as Iobopods, Pentastoma and Iophophorates. Newly discovered complete specimens by the ELI field team show that the taxon has, in addition to the 5 pairs of appendages, a pear-shaped trunk end bearing two or three circles of hooks. Accordingly based on these important morphological characters, reconsideration of its affinities is provided and the taxonomy is remedied herein. Because the five pairs of appendages of Facivermis yunnanicus resemble the appendages of the fore-trunk of Iobopod Miraluolishania （Liu ＆ Shu, 2004）, it seems that they are homologous structures. Therefore, the affinities of Facivermis are regarded here as being close to the Iobopods, in addition, the lobe-like appendages of Facivermis are very crucial to exploring the origin of the appendages of Iobopods and arthropods.     

The late Paleoproterozoic extension event:aulacogens and dyke Swarms in the North China craton

The extension structures and tectonic implication in the North China Craton ( NCC) are discussed in this paper based on the mafic dyke swarms and geochronology, combining with the geochronology of aulacogens. The late Paleoproterozoic time is the important turning point in the Precambrian evolution of the NCC. The extension system (e.g. aulacogens and dyke swarms) is widespread in the NCC, which marks the carbonization of the NCC with the rigid characteristic similar to the modern plate. The paleostress field modeling suggests that the dyke swarms and aulacogens are arogenic extension marking the start of the supercontinent, not synorogenic and post-orogenic extension. The mafic dyke swarms in the NCC mainly ranged from 1.83 to 1.77 Ga. The extension of the NCC is very limited brittle extension, the average extension ratio is only 0.35% given by mafic dyke swarms extension calculation, so most of extension in the NCC is contributed by the aulacogens. The mafic dyke swarms are related with the aulacogens in the origin.     

Numerical investigation of sinusoidal pulsating gas intake to intensify the gas–slag momentum transfer in the top-blown smelting furnace

The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method. The essential aspects of the fluid phase (e.g.,splashing volume, dead zone of copper slag, and gas penetration depth) were explored together with the effect of sinusoidal pulsating gas intake on the momentum-transfer performance between phases. The results illustrated that two relatively larg...     

Comparative study of Cambrian lobopods <Emphasis Type="Italic">Miraluolishania</Emphasis> and <Emphasis Type="Italic">Luolishania</Emphasis>

The rare fossil Miraluolishania described by Liu et ah from the Lower Cambrian Chengjiang Lagerstatte in 2004 is regarded as an arthropod sphinx because it bears mosaic features of both Iobopods and arthropods. The discovery of this rare transitional form offers direct fossil evidence for exploring the relationship between Iobopods and arthropods. However, some scientists consider Miraluolishania to be a junior synonym of Luolishania because the former superficially resembles the latter in general appearance. Considering the significant differences between the two taxa, a thorough comparative study of Miraluolishania and Luolishania leads to the conclusion that there are definitely two different genera. Nevertheless, the ＂Luolishania＂ of the Haikou area is indeed ＂Miraluolishania＂, whereas Luolishania is most likely the typical genus of the Maotianshan area of Chengjiang County.     

Using the biomarker bonded on the asphaltenes for biodegraded oil-source correlation

Ruthenium-ion-catalyzed oxidation(RICO)has been used to investigate asphaltenes from three oils with the same origin in the Juquan Basin and three oils with the same origin but with different degree of biodegradation in the Turpan Basin,Northwest China.The preliminary results showed that the biomarkers bonded on the asphaltenes with the same origin is similar and is correlated with the free biomarker in saturates.The bonded biomarkers have no relationship with the biodegradation.An application on the severely biodegraded oils is reported here.The biomarker and benznecarboxylic methyl esters reflecting t eh structure of the asphaltenes after RICO should provide a new way for oil-source correlation and it should be specially useful for severely biodegraded oil-source correlation.     

Hydrolysation and Characterization of Acrylic Fibers

Effect of the cationic surfactant on the hydrolysis of acrylic staple fiber dispersed in alkaline aqueous solution was studied.The cationic dyestuff uptake of the resultant hydrolysates was investigated as well.The results showed that the surfactant accelerated the hydrolysis of cyano-and ester-groups.The carboxyl content of the hydrolyzed fibers reached the maximum 6.85 mmol/g(i.e.,total molar conversion of the two groups 38.7%) while keeping fiber integrity.The scanning electron microscopy(SEM) images implied that hydrolysis happened both on fiber surface and in the inner part of the fiber in the presence of surfactant.The cationic dye removal due to adsorption onto the hydrolyzed fibers increased with increasing temperature,with the removal 97.4% at 60℃.The adsorption of the fibers followed the Freundlich's adsorption isotherm and the Lagergren's pseudo-second order dynamic equation with the activation energy 5.4 kJ/mol.Unexpectedly,the steric hindrance of access to the inside carboxyl groups of the hydrolyzed fibers caused a low dye sorption capacity,5-6 mg/g.     

Preparation of calcium carbonate particles coated with titanium dioxide

The preparation of a new mineral composite material, calcium carbonate particles coated with titanium dioxide, was studied. The mechanism of the preparation process was proposed. The new mineral composite material was made by the mechanoehemieal method under the optimum condition that the mass ratio of calcium carbonate particles to titanium dioxide was 6.5:3.5. The mass ratios of two different types of titanium dioxide (anatase to rutile) and grinding media to grinded materials were 8:2 and 4:1 respectively, and the modified density was 60%. Under this condition, the new material was capable of forming after 120-min modification. The hiding power and oil absorption of this new material were 29.12 g/m2 and 23.30%, respectively. The results show that the modification is based on surface hydroxylation. After coating with titanium dioxide, the hiding power of calcium carbonate can be improved greatly. The new mineral composite materials can be used as the substitute for titanium dioxide.     

The origin of the vertebrate jaw:Intersection between developmental biology-based model and fossil evidence

The origin of the vertebrate jaw has been reviewed based on the molecular,developmental and paleontological evidences.Advances in developmental genetics have accumulated to propose the heterotopy theory of jaw evolution,i.e.the jaw evolved as a novelty through a heterotopic shift of mesenchyme-epithelial interaction.According to this theory,the disassociation of the nasohypophyseal complex is a fundamental prerequisite for the origin of the jaw,since the median position of the nasohypophyseal placode in cyclostome head development precludes the forward growth of the neural-crest-derived craniofacial ectomesenchyme.The potential impacts of this disassociation on the origin of the diplorhiny are also discussed from the molecular perspectives.Thus far,our study on the cranial anatomy of galeaspids,a 435-370-million-year-old ’ostracoderm’ group from China and northern Vietnam,has provided the earliest fossil evidence for the disassociation of nasohypophyseal complex in vertebrate phylogeny.Using Synchrotron Radiation X-ray Tomography,we further show some derivative structures of the trabeculae(e.g.orbitonasal lamina,ethmoid plate) in jawless galeaspids,which provide new insights into the reorganization of the vertebrate head before the evolutionary origin of the jaw.These anatomical observations based on new techniques highlight the possibility that galeaspids are,in many respects,a better proxy than osteostracans for reconstructing the pre-gnathostome condition of the rostral part of the braincase.The cranial anatomy of galeaspids reveals a number of derived characters uniquely shared with gnathostomes.This raises the potential possibility that galeaspids might be the closest jawless relatives of jawed vertebrates.Our study provides an intriguing example of intersection between developmental biology-based model and fossil evidence.     

Some basic concepts and problems on the petrogenesis of intra-plate ocean island basalts

Basaltic magmatism that builds intra-plate ocean islands is often considered to be genetically associated with ＂hotspots＂ or ＂mantle plumes＂. While there have been many discussions on why ocean island basalts （OIB） are geochemically highly enriched as an integral part of the mantle plume hypothesis, our current understanding on the origin of OIB source material remains unsatisfactory, and some prevailing ideas need revision. One of the most popular views states that OIB source material is recycled oceanic crust （ROC）. Among many problems with the ROC model, the ocean crust is simply too depleted （e.g., [La/Sm]PM 〈1） to be source material for highly enriched （e.g., [La/Sm]pM 〉〉 1） OIB, Another popular view states that the enriched component of OIB comes from recycled continental crust （RCC, i.e.; terrigenous sediments）. While both CC and OIB are enriched in many incompatible elements （e.g., both have [La/Sm]PM 〉〉1）, the CC has characteristic enrichment in Pb and deletion in Nb, Ta, P and Ti. Such signature is too strong to be eliminated such that CC is unsuitable as source material for OIB. Plate tectonics and mantle circulation permit the presence of ROC and RCC materials in mantle source regions of basalts, but they must be volumetrically insignificant in contributing to basalt magmatism. The observation that OIB are not only enriched in incompatible elements, but also enriched in the progressively more incompatible elements indicates that the enriched component of OIB is of magmatic origin and most likely associated with low-degree melt metasomatism. H2O and CO2 rich incipient melt may form in the seismic low velocity zone （LVZ）. This melt will rise because of buoyancy and concentrate into a melt rich layer atop the LVZ to metasomatize the growing lithosphere, forming the metasomatic vein lithologies. Erupted OIB melts may have three components： （1） fertile OIB source material from depth that is dominant, （2） the melt layer, and （3） assimilation of the metasomatic vein lithologies formed earlier in the growing/grown lithosphere. It is probable that the fertile source material from depth may be （or contain） recycled ancient metasomatized deep portions of oceanic lithosphere. In any attempt to explain the origin of mantle isotopic end-members as revealed from global OIB data, we must （1） remember our original assumptions that the primitive mantle （PM） soon after the core separation was compositionally uniform/homogeneous with the core playing a limited or no role in causing mantle isotopic heterogeneity; （2） not use OIB isotopes to conclude about the nature and compositions of ultimate source materials without understanding geochemical consequences of subduction zone metamorphism; and （3） ensure that models and hypotheses are consistent with the basic petrology and major/trace element geochemistry.     

An Archean continental block in the Taihangshan and Hengshan regions: Constraints from geochronology and geochemistry

Recent research on the tectonothermal evolution and geochronology in the Fuping, Hengshan and Wutaishan metamorphic complexes, together with the discoveries of a high-pressure granulite belt in the northern margin of the North China Craton (NCC) and high-pressure metapelites in the Jingangku Group of the Wutaishan complex, suggests that there was a Neoarchean to Paleoproterozoic orogenic belt related to collision between the Eastern and Western continental blocks. Comparison of geological, geochronological, tectonothermal and geochemical data between the Fuping and Hengshan complexes suggests these two complexes most likely originated and evolved as a single lithotectonic domain (i.e., the Taihangshan-Hengshan block) during the early evolution of the North China Craton, probably as an active margin to the Eastern Continental Block. The Taihangshan-Hengshan block has been subjected to intensive and extensive tectono-magmatism and high-grade metamorphism related to collision between the Eastern and Western continental blocks at ～1.80 Ga.     

Aerodynamically Assisted Tip-Pen Direct Writing

Scaffolds require individual external shape and well-defined internal structure, which is of great importance for tissue engineering. Rapid prototyping (RP) uses layer-manufacturing strategies to create physical objects and has the advantage on scaffold fabrication. A new RP technology called aerodynamically assisted tip-pen direct writing was developed to construct the complex architectures. Compared with the traditional nozzle, the new nozzle has a micro-tip in the center of the micro-hole. The flow is determined by the gap between the micro-hole and micro-tip, which makes it practical for more accurate flow control. A highly accurate three-dimensional (3-D) micro-positioning system was employed with the new nozzle to deposit maltose structures. 3-D architectures had been made by this method, the width of fiber in which is about 120 μm. The results show that this method provides a possibility to construct 3-D scaffolds with tissue-scale features (i.e., 10-100 μm) without bad influence on the biological activities.     

The HITCR-I： Evaluation on a free gait generation method for the hexapod robot on irregular terrain

The purpose of this paper is to present and evaluate a method of free gait generation for HITCRI,a hexapod walking robot.The HITCR-I is designed as a modularized structure of legs that is based upon a four-bar linkage mechanism and with force sensors in the tip of legs,distributed hardware structure and a modular software structure of the control system.Based on a set of local rules between adjacent legs,finite state machine （FSM） model is built to control the coordination of legs.An automatic smooth transition of gait pattern is achieved through deriving the mathematical relation between gait pattern and locomotion parameters.The disordered inter-leg phase sequence is adjusted to a regular state smoothly and quickly by the local rules based FSM,and the gait pattern can transform automatically adapting to irregular terrain.The experiment on HITCR-I has demonstrated that it can walk through irregular terrain reliably and expeditiously with the free gait controller designed in this paper.     

A Chengjiang-type fossil assemblage from the Hongjingshao Formation （Cambrian Stage 3） at Chenggong,Kunming, Yunnan

A new Chengjiang-type fossil assemblage is reported herein from the lower part of the Hongjingshao Formation at Xiazhuang village of Chenggong,Kunming,Yunnan.The fossil assemblage,named as Xiazhuang fossil assemblage,yields predominantly soft-bodied fossils,including arthropods,brachiopods,priapulids,lobopods and some problematic taxa,with arthropods being the most dominant group.Preservation and composition of the fossil assemblage are very similar to the typical Chengjiang biota,which is preserved in the middle Yu’anshan Formation in the large area of eastern Yunnan.The associated trilobites demonstrate that the soft-bodied fossil assemblage belongs to the late Qiongzhusian in age(Stage 3,Cambrian),suggesting that the Hongjingshao Formation is probably a diachronous lithostratigraphic unit ranging from the upper Qiongzhusian to the lower Canglangpuan stages in eastern Yunnan.The fossil assemblage from the Xiazhuang area fills up the missing link between the typical older Chengjiang biota and the younger Malong and Guanshan biotas,making eastern Yunnan a unique area in the world to reveal the early evolutionary history of animals and palaeocommunity dynamics during the‘‘Cambrian explosion’’.     

Solid FeS lubricant:a possible alternative to MoS2 for Cu-Fe-based friction materials

Molybdenum disulfide (MoS₂) is one of the most commonly used solid lubricants for Cu-Fe-based friction materials. Nevertheless, MoS₂ reacts with metal matrices to produce metal sulfides (e.g., FeS) and Mo during sintering, and the lubricity of the composite may be related to the generation of FeS. Herein, the use of FeS as an alternative to MoS₂ for producing Cu-Fe-based friction materials was investigated. According to the reaction principle of thermodynamics, two composites-one with MoS₂ (Fe-Cu-MoS₂ sample) and the other with FeS (FeS-Cu₂S-Cu-Fe-Mo sample), were prepared and their friction behaviors and mechanical properties were compared. The results showed that MoS₂ reacted with the Cu-Fe matrix to produce FeS, metallic ternary sulfides, and Mo when sintered at 1050℃. The MoS₂-Cu-Fe and FeS-Cu₂S-Cu-Fe-Mo samples thereby exhibited similar characteristics with respect to phase composition, density, hardness, and tribological behaviors. Micrographs of the worn surfaces revealed that the stable friction regime for both composites stemmed from the iron sulfides friction layers rather than from the molybdenum sulfides layers.     

Personification algorithm for protein folding problem：Improvements in PERM

PERM is the most efficient approach for solving protein folding problem based on simple lattice model. In this article a personification explanation of PERM is proposed. A new version of PERM, population control algorithm with two main improvements is presented: one is that it is able to redefine the weight and its predicted value in PERM,and the other is that it is able to unify the calculation of weight when choosing possible branches. The improved PERM is more efficient than the previous version; specifically it can find the known lowest energy states for the four well-known difficult instances and is generally several to hundreds times faster than PERM. It is noteworthy that with the improved PERM we found new lowest energy configurations of three of the four difficult problems missed in previous papers.     

Workspace and rotational capability analysis of a spatial 3-DoF parallel manipulator

The analysis on the workspace and rotational capability of HANA, a spatial 3-DoF parallel manipulator, is concerned. The parallel manipulator consists of a base plate, a movable platform, and three connecting legs. The moving platform has three degrees of freedom (DoFs) which are two translations and one rotation, with respect to the base plate. The new parallel manipulator is very interesting for the reason of no singularity in the workspace, the single-DoF joint architecture and high rotational capability of the moving platform. The inverse kinematics problem is described in a closed-form, which is very useful to present the workspace geometrically. The constant-orientation and reachable workspaces for the manipulator are analyzed firstly. The index that is used to evaluate the rotational capability of the manipulator is defined and discussed in detail. Finally, the distribution of rotational capability index on the workspace is presented, which helps us know how much the index is at different point. The parallel manipulator has wide application in the fields of industrial robots, simulators, micro-motion manipulators, and parallel kinematics machines.     

Electrochemical performance of nickel oxide/KOH/active carbon super-capacitor

The fabrication and characterization of new type Nickel oxide/KOH/Active carbon super-capacitor have been described. Porous nickeloxide was prepared by hydrolysis of nickel acetate and heated in air at 300℃. The resulting nickel oxide behaved as an electrochemical capacitor electrode with a specific capacitance (50-70F/g) superior to most active carbon electrodes. This kind of nickel oxide maintained highutilization at high rate of discharge (i.e., high power density) and had excellent cycle life more than 1000 times, while the capacitance of the cell composed of two identical nickel oxide electrodes was poor at high discharge current density and the maximum operational voltage of this type capacitor was limited to 0.5V. A new type super-capacitorwas designed in which the nickel oxide and the active carbon were applied to the positive and negative electrodes respectively. The breakdown voltage of this type super-capacitor was improved effectively to 0.8V and excellent characteristic of high power discharge was attained in this way. The Nickel oxide/KOH/Active carbon super-capacitor has promising potentials in portable telecommunications, uninterruptable power supplies and battery load leveling applications.