A 3-Node Co-Rotational Triangular Finite Element for Non-Smooth,Folded and Multi-Shell Laminated Composite Structures

Based on the first-order shear deformation theory,a 3-node co-rotational triangular finite element formulation is developed for large deformation modeling of non-smooth,folded and multi-shell laminated composite structures.The two smaller components of the mid-surface normal vector of shell at a node are defined as nodal rotational variables in the co-rotational local coordinate system.In the global coordinate system,two smaller components of one vector,together with the smallest or second smallest component of another vector,of an orthogonal triad at a node on a non-smooth intersection of plates and/or shells are defined as rotational variables,whereas the two smaller components of the mid-surface normal vector at a node on the smooth part of the plate or shell(away from non-smooth intersections)are defined as rotational variables.All these vectorial rotational variables can be updated in an additive manner during an incremental solution procedure,and thus improve the computational efficiency in the nonlinear solution of these composite shell structures.Due to the commutativity of all nodal variables in calculating of the second derivatives of the local nodal variables with respect to global nodal variables,and the second derivatives of the strain energy functional with respect to local nodal variables,symmetric tangent stiffness matrices in local and global coordinate systems are obtained.To overcome shear locking,the assumed transverse shear strains obtained from the line-integration approach are employed.The reliability and computational accuracy of the present 3-node triangular shell finite element are verified through modeling two patch tests,several smooth and non-smooth laminated composite shells undergoing large displacements and large rotations.

Development of Composite Cellular Cores for Sandwich Panels Based on Folded Polar Quadra-Structures

An idea to develop a family of cellular cores for sandwich panels using a technology of prepreg folding is presented. Polar folded quadra structures are regarded as a geometric basis for these cores whose standard frag ment has lhe fourlh degree of axial symmelry. The classification of the polar strucluresaredeseribedanda method of various quadra slrueture synthesis is developed. A possibilily to provide high strength of lhe structure due m preservation of faces reinforcement pattern is presented. Arrangemen! of the plane core on a bi curvature surface is also introduced. Besides, provision of isotropyof the core in two or three directions are described. Finally, exam ples of cellular folded cores manufaclured from basalt reinforced plaslic are demonslrated.

Deformation, Stratigraphy, Structures and Shortening of the Zagros Fold-Thrust Belt in Southwest Iran Analysis by Restoration

A structural cross-section constructed across the Zagros Fold-Thrust Belt covering the Abadan Plain, Dezful Embayment, and Izeh Zone applied 2D and 3D seismic data, well data, surface and subsurface geological maps, satellite images and field reconnaissance. Besides validation and modification of the cross-section, restoration allows better understanding of the geology, structural style and stratigraphy of the Zagros basin. In the area of interest, the Hormuz basal decollement and the Gachsaran detachment play the most significant roles in the structural style and deformation of the Zagros belt. More complexity is associated with interval decollements such as Triassic evaporites, Albian shales and Eocene marls. A variety of lithotectonic units and detachment surfaces confound any estimation of shortening, which generally decreases with increasing depth. Deformation completely differs in the Abadan Plain, Dezful Embayment and Izeh Zone because of different sedimentation histories and tectonic evolution; gentle and young structures can be interpreted as pre-collisional structures of the Dezful Embayment before the Late Cretaceous. After the Late Cretaceous, the Mountain Front Fault is the main control of sedimentation and deformation in the Zagros Basin, and this completely characterizes fold style and geometry within the Dezful Embayment and the Izeh Zone.

Functional structures and folding dynamics of two peptides

The folding dynamics and structural characteristics of peptides RTKAWNRQLYPEW （P1） and RTKQLYPEW （P2） are investigated by using all-atomic simulation procedure CHARMM in this work. The results show that P1, a segment of an antigen, has a folding motif of α-helix, whereas P2, which is derived by deleting four residues AWNR from peptide P1, prevents the formation of helix and presents a β-strand. And peptlde P1 experiences a more rugged energy landscape than peptide P2. From our results, it is inferred that the antibody CD8 cytolytic T lymphocyte prefers an antigen with a β-folding structure to that with an α-helical one.

Elaboration of Simplest Folding Structures in 2-Dimensional Lattice with Delta-Hemolysin and Its Variants in HP Model

Although the advanced 3-dimensional structure measurements provide more and more detailed structures in Protein Data Bank, the simplest 2-dimensional lattice model still looks meaningful because 2-dimensional structures play a complementary role with respect to 3-dimensional structures. In this study, the folding structures of delta-hemolysin and its six variants were studied at 2-dimensional lattice, and their amino acid contacts in folding structures were considered according to HP model with the aid of normalized amino acid hydrophobicity index. The results showed that: 1) either delta-hemolysin or each of its variants could find any of its folding structure in one eighth of 1,129,718,145,924 folding structures because of symmetry, which reduces the time required for folding, 2) the impact of pH on folding structures is varying and associated directly with the amino acid sequence itself, 3) the changes in folding structures of variants appeared different case by case, and 4) the assigning of hydrophobicity index to each amino acid was a way to distinguish folding structures at the same native state. This study can help to understand the structure of delta-hemolysin, and such an analysis can shed lights on NP-problem listed in millennium prize because the HP folding in lattice belongs to a sub-problem of NP-problem.

Three-dimensional Evolutionary Models of the Qiongxi Structures,Southwestern Sichuan Basin,China:Evidence from Seismic Interpretation and Geomorphology

Fold terminations are key features in the study of compressional fault-related folds. Such terminations could be due to loss of displacement on the thrust fault or/and forming a lateral or oblique ramp. Thus, high-quality seismic data would help unambiguously define which mechanism should be responsible for the termination of a given fault-related fold. The Qiongxi and Qiongxinan structures in the Sichuan Basin, China are examples of natural fault-propagation folds that possess a northern termination and a structural saddle between them. The folds/fault geometry and along-strike displacement variations are constrained by the industry 3-D seismic volume. We interpret that the plunge of the fold near the northern termination and the structural saddle are due to the loss of displacement along strike. The fault geometry associated with the northern termination changes from a flat-ramp at the crest of the Qiongxinan structure, where displacement is the greatest, to simply a ramp near the northern tip of the Qiongxi structure, without forming a lateral or oblique ramp. In this study, we also use the drainage pattern, embryonic structure preserved in the crest of the Qiongxinan structure and the assumption that displacement along a fault is proportional to the duration of thrusting to propose a model for the lateral propagation of the Qiongxinan and Qiongxi structures. Specifically, we suggest that the structure first initiated as an isolated fault ramp within brittle units. With increased shortening, the fault grows to link with lower detachments in weaker shale units to create a hybridized fault-propagation fold. Our model suggests a possible explanation for the lateral propagation history of the Qiongxinan and Qiongxi structures, and also provides an alternative approach to confirming the activity of the previous Pingluoba structure in the southwestern Sichuan Basin in the late Cenozoic.

Crashworthiness of innovative hexagonal honeycomb-like structures subjected to out-of-plane compression

Seeking for innovative structures with higher mechanical performance is a continuous target in railway vehicle crashworthiness design.In the present study,three types of hexagonal reinforced honeycomb-like structures were developed and analyzed subjected to out-of-plane compression,namely triangular honeycomb(TH),double honeycomb(DH)and full inside honeycomb(FH).Theoretical formulas of average force and specific energy absorption(SEA)were constructed based on the energy minimization principle.To validate,corresponding numerical simulations were carried out by explicit finite element method.Good agreement has been observed between them.The results show that all these honeycomb-like structures maintain the same collapsed stages as conventional honeycomb;cell reinforcement can significantly promote the performance,both in the average force and SEA;full inside honeycomb performs better than the general,triangular and double schemes in average force;meanwhile,its SEA is close to that of double scheme;toroidal surface can dissipate higher plastic energy,so more toroidal surfaces should be considered in design of thin-walled structure.These achievements pave a way for designing high-performance cellular energy absorption devices.

Does mRNA structure contain genetic information for regulating co-translational protein folding？

Currently many facets of genetic information are illdefined. In particular, how protein folding is genetically regulated has been a long-standing issue for genetics and protein biology. And a generic mechanistic model with supports of genomic data is still lacking. Recent technological advances have enabled much needed genome-wide experiments. While putting the effect of codon optimality on debate, these studies have supplied mounting evidence suggesting a role of m RNA structure in the regulation of protein folding by modulating translational elongation rate. In conjunctions with previous theories, this mechanistic model of protein folding guided by m RNA structure shall expand our understandings of genetic information and offer new insights into various biomedical puzzles.

Helical Coordination Polymer with a 3-Fold Interpenetration Structure Based on 5-(Hydroxymethyl)isophthalic Acid

5-（Hydroxymethyl） isophthalic acid （H2HIA） as a novel organic ligand was prepared from 3,5-bis（methoxycarbonyl）benzoic acid by a two-step method. And then, a 3D helical coor- dination polymer with a 3-fold interpenetration structure, namely [Zn1/2（HIA）1/2（DPEE）1/2]n （1）, was hydrothermally synthesized at 160 ℃, using H2HIA ligands to assemble with DPEE ligands and Zn2＋ ions. Complex 1 crystalizes in orthorhombic system, space group Pnna, with a = 8.2118（5）, b = 17.1698（7）, c =14.9922（7） ？, V = 2113.82（18） ？3, μ = 1.194 mm-1, Z = 4 and S = 0.967. Moreover, some physical characteristics of complex 1, such as powder X-ray diffraction （PXRD）, thermogravimetry analyses （TGA） and photoluminescent properties, were also investigated.

Two Interpenetrated and Polycatenated Zn(Ⅱ)Coordination Polymers:Syntheses,Structures and Luminescent Properties

Two fascinating Zn（II）entangled coordination polymers,[Zn（eoba）(bbi)];·nH;O（1）and[Zn（boba）(bbi);];（2）,(bbi=1,1?-（1,4-butanediyl）-bis（imidazole）,H;eoba=4,4?-（ethane-1,2-diyldioxy）-dibenzoic acid,H;boba=4,4?-（butane-1,4-diyldioxy）-dibenzoic acid),were obtained by hydrothermal technology and characterized by elemental analysis,infrared spectrum,thermogravimetric analysis and single-crystal X-ray diffraction.1 is a rare 2D→3D example with a 3-fold parallel interpenetration and polycatenaned architecture.2 features a scarce2D→2D example with a 3-fold parallel interpenetrating network which possesses polyrotaxane and polycatenane characters.Moreover,the luminescent properties of 1 and 2 have been discussed.

Protein structural codes and nucleation sites for protein folding

One of the long-standing controversial arguments in protein folding is Levinthal＇s paradox. We have recently proposed a new nucleation hypothesis and shown that the nucleation residues are the most conserved sequences in protein. To avoid the complicated effect of tertiary interactions, we limit our search for structural codes to the nucleation residues. Starting with the hypotheses of secondary structure nucleation and conservation of residues important for folding, we have analysed 762 folds classified as unique by SCOP. Segments of 17 residues around the top 20% conserved amino acids are analysed, resulting in approximately 100 clusters each for the main secondary structure classes of helix, sheet and coil. Helical clusters have the longest correlation range, coils the shortest （four residues）. Strong specific sequence-structure correlation is observed for coil but not for helix and sheet, suggesting a mapping relationship between the sequence and the structure for coil. We propose that the central sequences in these clusters form ＇structural codes＇, a useful basis set for identifying nucleation sites, protein fragments stable in isolation, and secondary structural patterns in proteins （particularly turns and loops）.

Fractals of Protein Backbone Structures

Ths paper，based on the principles of geometric self-similarity of fractal theory and some research results of rotein chemistry，improved the method of comput－ing protein fractal dimensions，and computed fractal dimensions of some protein back bone，secondary and assumed folding structures．The relationship between protein back-bone strucrural fractal dimensions and its spatial structures was investigated．The results indicated that protein backbone fractal dimensions not only have a close relation with protein secondary structure，but also with its folding．In addition，the folding of protein Polypeptide chains in 3-D space may be similar to the other macromolecular chain be haviour described by the self-avoiding walks（SAW）model．

Simulating the Folding Pathway of RNA Secondary Structure Using the Modified Ant Colony Algorithm

A new method for simulating the folding pathway of RNA secondary structure using the modified ant colony algorithmis proposed.For a given RNA sequence,the set of all possible stems is obtained and the energy of each stem iscalculated and stored at the initial stage.Furthermore,a more realistic formula is used to compute the energy ofmulti-branch loop in the following iteration.Then a folding pathway is simulated,including such processes as constructionof the heuristic information,the rule of initializing the pheromone,the mechanism of choosing the initial andnext stem and the strategy of updating the pheromone between two different stems.Finally by testing RNA sequences withknown secondary structures from the public databases,we analyze the experimental data to select appropriate values forparameters.The measure indexes show that our procedure is more consistent with phylogenetically proven structures thansoftware RNAstructure sometimes and more effective than the standard Genetic Algorithm.

Investigation of Highly Designable Dented Structures in HP Model with Hydrogen Bond Energy

Some highly designable protein structures have dented on the surface of their native structures, and are not full compactly folded. According to hydrophobic-polar （HP） model the most designable structures are full compactly folded. To investigate the designability of the dented structures, we introduce the hydrogen bond energy in the secondary structures by using the secondary-structure-favored HP model proposed by Ou-yang etc. The result shows that the average designability increases with the strength of the hydrogen bond. The designabilities of the structures with same dented shape increase exponentially with the number of secondary structure sites. The dented structures can have the highest designabilities for a certain value of hydrogen bond energy density.

FEATURES AND MINING GEOLOGY SIGNIFICANCES OF THE COAL SEAM SLIP FOLD STRUCTURE IN XU-HUAI DISTRICT

In the analysis of some in-seam slip fold structures in the area of Xuzhou and Huaibei Districta it is noted that there exist some in-seam roof and footwall rock layers extremely incompatible to the existence of coal seams. Some of them are tbe slip fold structures that are wedged into coal seam by folding, but all of them are passively generated by in-seam shearing forces. In this paper, a discussion is put forward of the damage to coal seams by slip folds and the coal mining significance resulted from the study of slip fold structures.

Synthesis, Crystal Structure and Gas Adsorption of a Two-fold Interpenetrated Three-dimensional Framework {[Cd(2-NO_2-BDC)(4,4？-DPA)]·(DMF)}_n

The reaction of Cd（NO_3）_2·4H_2O with 4,4？-dipyridylacetylene（4,4？-DPA） and 2-nitroterephthalic acid（2-NO_2-H_2BDC） in DMF/H_2O mixed solvent has afforded a compound {[Cd（2-NO_2-BDC）（4,4？-DPA）]·（DMF）}_n（1）. Compound 1 has been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetry analysis, and IR spectrum. Compound 1 crystallizes in the monoclinic system, space group P21/n, with a = 12.1488（3）, b = 14.6689（3）, c = 13.1615（3） ？, β = 111.809（3）o, V = 2177.63（9） ？~3, Z = 4, C_（23）H_（18）N_4O_7 Cd, M_r = 574.81, D_c = 1.753 g/cm^3, μ = 8.523 mm^（-1）, F（000） = 1152, the final R = 0.0411 and wR = 0.1064 for 3589 observed reflections with I 〉 2s（I）. In compound 1, the Cd（Ⅱ） ions are linked by the carboxylate groups of 2-NO_2-BDC ligands to give a two-dimensional layered structure based on the centrosymmetric dinuclear Cd_2（COO）_2 units, which are further connected by the 4,4？-DPA ligands to produce a three-dimensional framework with pcu topology. Careful examination revealed that compound 1 is a 2-fold interpenetrating framework. Furthermore, the gas adsorption properties of 1 for N_2 and CO_2 have also been investigated.

Structural and Chemical Characteristic of Tourmaline, and Mineralogy of Associated Micas from Tourmaline Bearing Quartzite of KombéII (Bafia Group, Central Africa Fold Belt);Implication on the Metamorphic Conditions

Bafia Group is part of the southernmost portion of the Central African Fold Belt (CAFB) in Cameroon. The geological feature of the group is characterized by the presence of metamorphic rocks in which tourmaline had been recognized among accessory minerals. In the present study, attention is focus on the tourmaline bearing quartzite to the southeast of Kombé II. Structure refinement shows that tourmaline is a Fe-dravite with the formula X(Na0.95[]0.05)Y(Mg2.39Fe0.61)Z(Al5.10Mg0.90)(BO3)3T[Si6O18](OH)3[(O,OH)0.88F0.12]. The Fe-dravite is hosted in a Ca-poor quartzite, which is made up, in addition to quartz and tourmaline, of biotite and muscovite. The structure of the dravites shows a low vacancy at the X site, which militates for a crystallization of the tourmaline at a high temperature > 750℃. This is in agreement with previous work which shows that the metamorphic peak in the associated biotite gneiss reaches 825℃. The R1 value of 1.24% means that the crystal structure of the tourmalines is of high quality. The genetical link between gold mineralization and tourmaline should stimulate exploration interest in the study area.

Compact Solvmanifolds with a Closed G₂-Structure

We consider a parametrized family of compact G2-calibrated solvmanifolds, and construct associative (so volume-minimizing submanifolds) 3-tori with respect to the closed G2-structure. We also study the Laplacian flow of this closed G2 form on the solvable Lie group underlying to each of these solvmanifolds, and show long time existence of the solution.

Structure-activity correlationship and folding of recombinant Escherichia coli dihydro folate reductase (DHFR) enzyme through biochemical and biophysical approaches

The design of any antagonist or inhibitor for any enzyme requires the knowledge of structure- function relationship of the protein and the optimum conformational states for maximum and minimum activities. Furthermore, designing of the inhibitors or drugs against an enzyme becomes easier if there is information available about various well characterized intermediate conformation of the molecule. In vivo folding pathway of any recombinant protein is an important parameter for understanding its ability to fold by itself inside the cell, which always dictates the downstream processing for the purification. In the present manuscript we have discussed about the in vivo and in vitro folding, and structure-function relationship of Dihydrofolate reductase enzyme. This is an important enzyme involved in the cell growth and hence inhibition or inactivation of the enzyme may reduce the cell growth. It was observed that the equilibrium unfolding transition of DHFR proceeds through the formation of intermediates having higher exposed surface hydrophobicity, unchanged enzymatic activity and minimum changes in the secondary structural elements. Because of enhanced surface hydrophobicity, and unchanged enzymatic activity, these intermediates could be a nice target for designing drugs against DHFR.

Crustal structure in northern margin of Tianshan mountains and seismotectonics of the 1906 Manas earthquake

长86 km、南北向横跨乌鲁木齐坳陷的深地震反射剖面,揭示了北天山山前地壳的薄皮构造特征.共深度点叠加剖面的石河子以南部分显示了天山北缘平行山体的第一和第二排背斜构造.与双程时间分别为2.5～3.0s和5.5～6.0s的反射事件对应的滑脱构造,将地壳深部构造与地表逆断裂-褶皱构造联系在一起.玛纳斯断裂以铲形方式向下延伸,在2.5s左右深度归并于第一滑脱面,向南与清水河断裂汇合.在5.5～6.0s深度上为与玛纳斯下背斜相连的主滑脱面.它们最终汇集到准噶尔南缘断裂.石河子以北的坳陷沉积深度达12～14km.沿剖面的莫霍界面深度在准噶尔盆地为45km左右,往南加深至50km.对该区域内的深地震测深剖面和布格重力异常资料的分析结果,与深反射剖面的地壳结构图象具有一致性.深地震反射剖面通过1906年玛纳斯7.7级地震宏观震中区,共深度点叠加剖面用于推断玛纳斯7.7级地震与北天山山前地壳构造之间的关系:玛纳斯地震属于一类“褶皱地震”,其发震构造是由准噶尔南缘断裂、清水河逆冲断裂、滑脱面和玛纳斯浅部断坡组成的断层系.