Journal articles: 'Manifold assembly'

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Martin, Alex, George Dellopoulos, Paul Edwards, Andreas Furmanek, Stefan Gicquel, Brian Macklin, Patrick Martin, Mario Merola, Mark Norman, and Rene Raffray. "ITER blanket manifold system: Integration, assembly and maintenance." Fusion Engineering and Design 89, no. 9-10 (October 2014): 2257–61. http://dx.doi.org/10.1016/j.fusengdes.2014.04.013.

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Bak, A., and Yu V. Muranov. "Normal invariants of manifold pairs and assembly maps." Sbornik: Mathematics 197, no. 6 (June 30, 2006): 791–811. http://dx.doi.org/10.1070/sm2006v197n06abeh003778.

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DeGaspari, John. "Trimming in a Snap." Mechanical Engineering 122, no. 07 (July 1, 2000): 74–76. http://dx.doi.org/10.1115/1.2000-jul-6.

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This article emphasizes on the use of thermoplastics in engines. One case in point is a reinforced nylon multifunctional module involving three components—air intake manifold, cam cover, and design cover-on the Alfa Romeo 156 engine. The project was a collaboration of Rhodia Engineering Plastics of France, Robert Bosch GmbH of Germany, and Magneti Marelli S.p.A. of Italy, system supplier for Fiat, which manufactures the Alfa Romeo. The article also shows an example where an under-the-hood reinforced nylon module on the Alfa Romeo 156 engine saved weight, allowed part integration, and incorporated a snap-fit assembly technique. According to an expert, the nylon also made possible more efficient assembly techniques. The air intake manifold, for example, is assembled using snap-fits, eliminating the need for welding or screw. The part provides high dimensional stability, good heat distortion temperature, and resistance to oils.

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Mohades, Mohamad Mahdi, Sina Majidian, and Mohammad Hossein Kahaei. "Haplotype Assembly Using Manifold Optimization and Error Correction Mechanism." IEEE Signal Processing Letters 26, no. 6 (June 2019): 868–72. http://dx.doi.org/10.1109/lsp.2019.2910383.

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Raptis, George, and Wolfgang Steimle. "Topological manifold bundles and the $A$-theory assembly map." Proceedings of the American Mathematical Society 148, no. 9 (April 22, 2020): 3787–99. http://dx.doi.org/10.1090/proc/15014.

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Tutunea, Dragos, Alexandru Oprica, Ana Maria Nicu, Diana Camelia Staicu, and Ilie Dumitru. "CFD and Structural Analysis of the Intake Manifold Flap of an Internal Combustion Engine." Applied Mechanics and Materials 880 (March 2018): 195–200. http://dx.doi.org/10.4028/www.scientific.net/amm.880.195.

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The objective of this study is to analyze the flow filed in the intake manifold using Computational Fluid Dynamics (CFD). The main function of the intake manifold flap is to regulate the air flow and to uniformly distribute in the cylinders. If the air is distributed uneven to the engine the volumetric efficiency, power and fuel consumption is reduced. The finite element method can be used to optimize the throttle flap. The results in the simulation offer valuable information’s of the flow field in the throttle assembly. The results show that the CFD model can be used as a tool for improve and optimize various part of the intake manifold flap.

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Cardoen, Grégoire, Kurt Breitenkamp, Todd Emrick, and E. Bryan Coughlin. "Manifold Assembly for the Convenient Polymerization of Ethylene Oxide and Butadiene." Macromolecules 39, no. 20 (October 2006): 7170–73. http://dx.doi.org/10.1021/ma061379y.

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Song, Shaotang, Lulu Wang, Jie Su, Zhen Xu, Chia-Hsiu Hsu, Chenqiang Hua, Pin Lyu, et al. "Manifold dynamic non-covalent interactions for steering molecular assembly and cyclization." Chemical Science 12, no. 35 (2021): 11659–67. http://dx.doi.org/10.1039/d1sc03733a.

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Villaret, Vincent, Frederic Deschaux-Beaume, Jean Marie Fortain, Gilles Fras, and Fabien Januard. "Weldability of New Ferritic Stainless Steel for Exhaust Manifold Application." Advanced Materials Research 445 (January 2012): 777–82. http://dx.doi.org/10.4028/www.scientific.net/amr.445.777.

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In the current context of fossil energy scarcity, car manufacturers have to optimize vehicles energy efficiency. This and continuous improvement includes a change of the exhaust manifold design. Usually in cast iron, exhaust manifolds tend to be mechanically welded in order to fit new constraints such as lightness, durability, efficiency and small size. To achieve such requirements, ferritic stainless steels with high chromium content (19%) and molybdenum (2%) are developed. For the welding, the use of existing filler wire does not satisfy fully the application requirements. This leads to oxidation problems and / or thermal fatigue strength that drastically reduces assembly lifetime. New flux cored wires are developed in the context of this study in order to provide molten zone characteristics close to those of the base metal. Different chemical compositions are tested in order to highlight the influence of stabilizing element on microstructure. Welding tests revealed the major influence of titanium on the grain refinement in the molten zone. A minimum Ti content of 0.45 weight % in the filler wire is required to be efficient as grain refiner.

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Jin, Y. W., W. Liu, Yi Yang Zhao, and C. Wang. "The Micro-Patterning of Polymer in the Presence of Porphyrin via Electrospinning." Solid State Phenomena 121-123 (March 2007): 653–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.653.

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Functional self-assembled structure with well-defined shapes and dimensions are of great current interest. Porphyrins are attractive building manifold patterning for these structures because of their electronic, optical, and catalytic properties. In this paper, we report a novel technique for the assembly patterning of polymers. An Electrospinning process was used to create patterning with diameter ranging from 3 μm to 4 μm and length of up to several hundred micrometers in the presence of Zinc Porphyrin. Scanning electron microscopy (SEM), UV- visible spectra and EDX spectra were used to characterize the patterning. The results indicated that the patterning depended on the concentration of Porphyrin and the operational conditions.

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Hey wood, Brigid R., and Caroline German. "Molecular routes to the formation of ordered inorganic arrays." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 478–79. http://dx.doi.org/10.1017/s0424820100170128.

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Anisotropic inorganic materials are desirable as they possess unique physical and chemical properties resulting from the manner in which the particulate components assemble. The facility to control the ordering of colloidal inorganic particles could presage dramatic improvements in the fabrication of ceramics, catalysts or paints. Biological systems have already harnessed the manifold advantages of such materials, consider shells, teeth, bones etc.(Figures 1 & 2). Synthetic strategies for the formation of nanodimensional inorganic solids abound but there are few reliable methods currently available for directing their subsequent aggregation. Some degree of ordering can be achieved by the application of external forces (magnetic, electrical) but the aggregates readily dissemble once the stimulus is removed. The requirement is, therefore, for an effective molecular route to the ordered assembly and construction of hierarchical inorganic microstructures.The present work forms part of an extended programme of research investigating crystal tectonics, the ordering of nanodimensional inorganic solids. Here, the controlled morphological tailoring of inorganic crystals to yield a form which favours self-assembly has been investigated.

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Das, Santu, Saurabh Kumar, Apabrita Mallick, and Soumyajit Roy. "Competitive Self-Assembly Manifests Supramolecular Darwinism in Soft-Oxometalates." Journal of Molecular and Engineering Materials 03, no. 01n02 (March 2015): 1540008. http://dx.doi.org/10.1142/s2251237315400080.

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Topological transformation manifested in inorganic materials shows manifold possibilities. In our present work, we show a clear topological transformation in a soft-oxometalate (SOM) system which was formed from its polyoxometalate (POM) precursor [ PMo 12 @Mo 72 Fe 30]. This topological transformation was observed due to time dependent competitive self-assembly of two different length scale soft-oxometalate moieties formed from this two-component host–guest reaction. We characterized different morphologies by scanning electron microscopy, electron dispersive scattering spectroscopy, dynamic light scattering, horizontal attenuated total reflection–infrared spectroscopy and Raman spectroscopy. The predominant structure is selected by its size in a sort of supramolecular Darwinian competition in this process and is described here.

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BAUCKHAGE, CHRISTIAN, ELKE BRAUN, and GERHARD SAGERER. "FROM IMAGE FEATURES TO SYMBOLS AND VICE VERSA — USING GRAPHS TO LOOP DATA- AND MODEL-DRIVEN PROCESSING IN VISUAL ASSEMBLY RECOGNITION." International Journal of Pattern Recognition and Artificial Intelligence 18, no. 03 (May 2004): 497–517. http://dx.doi.org/10.1142/s0218001404003198.

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Graphs and graph matching are powerful mechanisms for knowledge representation, pattern recognition and machine learning. Especially in computer vision their application is manifold. Graphs can characterize relations among image features like points or regions but they may also represent symbolic object knowledge. Hence, graph matching can accomplish recognition tasks on different levels of abstraction. In this contribution, we demonstrate that graphs may also bridge the gap between different levels of knowledge representation. We present a system for visual assembly monitoring that integrates bottom-up and top-down strategies for recognition and automatically generates and learns graph models to recognize assembled objects. Data-driven processing is subdived into three stages: first, elementary objects are recognized from low-level image features. Then, clusters of elementary objects are analyzed syntactically; if an assembly structure is found, it is translated into a graph that uniquely models the assembly. Finally, symbolic models like this are stored in a database so that individual assemblies can be recognized by means of graph matching. At the same time, these graphs enable top-down knowledge propagation: they are transformed into graphs which represent relations between image features and thus describe the visual appearance of the recently found assembly. Therefore, due to model-driven knowledge propagation assemblies may subsequently be recognized from graph matching on a lower computational level and tedious bottom-up processing becomes superfluous.

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Alshare, Aiman A., Fedrico Calzone, and Maurizio Muzzupappa. "Hydraulic manifold design via additive manufacturing optimized with CFD and fluid-structure interaction simulations." Rapid Prototyping Journal 25, no. 9 (October 14, 2019): 1516–24. http://dx.doi.org/10.1108/rpj-03-2018-0064.

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Purpose The purpose of this study is to investigate the feasibility of using additive manufacturing (AM) technique to produce an efficient valve manifold for hydraulic actuator by redesigning valve blocks produced by conventional methods. Design/methodology/approach A priori, a computational fluid dynamics (CFD) analysis was carried out using the software ANSYS Fluent to determine the optimal flow path that results in least pressure drop, highest average velocity and least energy losses. Fluid–structure interaction (FSI) simulations, processed with imported pressure distribution from the CFD, were conducted to determine the resulting loading and deformations of the manifold assembly. Findings The new design offers a 23 per cent reduction of oil volume in the circuit, while weighing 84 per cent less. When using the new design, a decrease of pressure drop by nearly 25 per cent and an increase in the average velocity by 2.5 per cent is achieved. A good agreement, within 16 per cent, is found in terms of the pressure drop between the experiment and computational model. Originality/value It is possible to build an efficient hydraulic manifold design by iterative refinement for adequate production via selective laser melting (SLM) and minimize used material to circumventing building support structures in non-machinable features of the manifold.

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Chao, Yu-Jo, Kan Wu, Hsun-Hui Chang, Ming-Jou Chien, and Jerry Chun Chung Chan. "Manifold of self-assembly of a de novo designed peptide: amyloid fibrils, peptide bundles, and fractals." RSC Advances 10, no. 49 (2020): 29510–15. http://dx.doi.org/10.1039/d0ra04480f.

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The amyloidogenic peptide EGAGAAAAGAGE can form fractal assembly on a two-dimensional surface under alkaline conditions, for which the counter cations have imparted structural rigidity to the C- and N- termini.

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Knoche, Thomas, and Gunther Reinhart. "Electrolyte Filling of Large-Scale Lithium-Ion Batteries: Challenges for Production Technology and Possible Approaches." Applied Mechanics and Materials 794 (October 2015): 11–18. http://dx.doi.org/10.4028/www.scientific.net/amm.794.11.

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Lithium-ion batteries have been the dominant energy storage technology in consumer electronics for several years and meanwhile advanced into e-mobility and stationary applications. The trend towards large-scale batteries presents manifold challenges to production technology. One decisive assembly process is filling electrolyte liquid into the battery case. This paper discusses the main influences and challenges for production technology concerning this crucial manufacturing process and how they are addressed. First preliminary results are presented.

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Gerbracht, Jennifer V., and Niels H. Gehring. "The exon junction complex: structural insights into a faithful companion of mammalian mRNPs." Biochemical Society Transactions 46, no. 1 (January 19, 2018): 153–61. http://dx.doi.org/10.1042/bst20170059.

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During splicing, the exon junction complex (EJC) is deposited upstream of exon-exon boundaries. The EJC and its peripheral bound proteins play an essential role in mediating mRNA export, translation and turnover. However, the exact sequence of EJC assembly and the involved factors during splicing remain elusive. Recently published structures of the human C* spliceosome clarified the position of the EJC at this phase of splicing and have given insight into previously unidentified interactions between the EJC and spliceosomal proteins. Here, these new observations are presented and the significance for EJC assembly is discussed. Furthermore, the vast landscape of EJC interacting proteins and their manifold functions are described. Finally, the factors involved in EJC disassembly and recycling are recapitulated. This review aims to integrate structural, biochemical and physiological data to obtain a comprehensive picture of EJC components during the lifetime of the EJC.

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Oguri, Hiroki. "Biomimetic Assembly Lines Producing Natural Product Analogs: Strategies from a Versatile Manifold to Skeletally Diverse Scaffolds." Chemical Record 16, no. 2 (February 1, 2016): 652–66. http://dx.doi.org/10.1002/tcr.201500213.

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Perrot, Denis. "The equivariant index theorem in entire cyclic cohomology." Journal of K-Theory 3, no. 2 (May 28, 2008): 261–307. http://dx.doi.org/10.1017/is008004027jkt047.

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AbstractLet G be a locally compact group acting smoothly and properly by isometries on a complete Riemannian manifold M, with compact quotient G\M. There is an assembly map which associates to any G-equivariant K-homology class on M, an element of the topological K-theory of a suitable Banach completion of the convolution algebra of continuous compactly supported functions on G. The aim of this paper is to calculate the composition of the assembly map with the Chern character in entire cyclic homology . We prove an index theorem reducing this computation to a cup-product in bivariant entire cyclic cohomology. As a consequence we obtain an explicit localization formula which includes, as particular cases, the equivariant Atiyah-Segal-Singer index theorem when G is compact, and the Connes-Moscovici index theorem for G-coverings when G is discrete. The proof is based on the bivariant Chern character introduced in previous papers.

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Uddin, Mohammad Nashir. "Towards Good Urban Local Governance in Bangladesh: Lessons learnt from Japanese Local Government System to Overcome the Challenges." Lex localis - Journal of Local Self-Government 11, no. 4 (September 19, 2013): 933–53. http://dx.doi.org/10.4335/11.4.933-953(2013).

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Rapid increase of size and demands of the urban population are causing manifold challenges for urban local governance in Bangladesh whereas Japan has successfully tackled similar challenges during last half century by adopting various policy measures at considerable cost. Among those, Bangladesh might easily consider several for her urban governance and development. This paper attempted to find out some policy options that Bangladesh could adopt from Japanese practices and experiences. Accordingly, an explanatory-descriptive design has been employed for content analysis in order to draw logical arguments regarding local autonomy, city governance, local assembly, financial autonomy, environmental and disaster management. Finally, the study concludes that lesson learning is essential but is neither sufficient nor indicative of an exact path to follow.

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Park, K. S., B. J. Kim, and Young Hoon Moon. "Effect of Heat Treatment Conditions on Tube Hydroformability." Materials Science Forum 475-479 (January 2005): 4137–40. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.4137.

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Tube hydroforming provides a number of advantages over conventional stamping process, including fewer secondary operations, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength and stiffness. It can produce wide range of products such as sub-frame, engine cradle, and exhaust manifold. In this study, the effect of heat treatment conditions, such as post seam annealing(PSA) and bright annealing(BA), on the ovality and hydro-formability of steel tubes has been investigated. Hydroformability has been estimated as the bulging height obtained depending on the various process parameters such as an internal pressure, axial feeding, and heat treatment conditions. The ovality and forming height were found to strongly depend on material properties after heat treatments.

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Kuramoto, Yoshiki. "Phase- and Center-Manifold Reductions for Large Populations of Coupled Oscillators with Application to Non-Locally Coupled Systems." International Journal of Bifurcation and Chaos 07, no. 04 (April 1997): 789–805. http://dx.doi.org/10.1142/s0218127497000595.

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In the first half of this paper, some general ideas will be developed on how to approach mathematically large systems of coupled limit-cycle oscillators. Two representative reduction techniques, namely, the phase reduction and the center-manifold reduction will be presented for a prototypal system of biological cell assembly with periodic activity. The evolution equation derived through each reduction method is further classified into three groups according to the range of the oscillator coupling (i.e. local, global and intermediate). As a consequence, six classes of model equations are obtained. In the second half of the paper, some new results from our recent study on non-locally coupled oscillators will be reported, and the generation of anomalous turbulent fluctuations obeying a power law will be discussed in some detail.

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Martin, Andrea E. "A Compositional Neural Architecture for Language." Journal of Cognitive Neuroscience 32, no. 8 (August 2020): 1407–27. http://dx.doi.org/10.1162/jocn_a_01552.

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Hierarchical structure and compositionality imbue human language with unparalleled expressive power and set it apart from other perception–action systems. However, neither formal nor neurobiological models account for how these defining computational properties might arise in a physiological system. I attempt to reconcile hierarchy and compositionality with principles from cell assembly computation in neuroscience; the result is an emerging theory of how the brain could convert distributed perceptual representations into hierarchical structures across multiple timescales while representing interpretable incremental stages of (de)compositional meaning. The model's architecture—a multidimensional coordinate system based on neurophysiological models of sensory processing—proposes that a manifold of neural trajectories encodes sensory, motor, and abstract linguistic states. Gain modulation, including inhibition, tunes the path in the manifold in accordance with behavior and is how latent structure is inferred. As a consequence, predictive information about upcoming sensory input during production and comprehension is available without a separate operation. The proposed processing mechanism is synthesized from current models of neural entrainment to speech, concepts from systems neuroscience and category theory, and a symbolic-connectionist computational model that uses time and rhythm to structure information. I build on evidence from cognitive neuroscience and computational modeling that suggests a formal and mechanistic alignment between structure building and neural oscillations, and moves toward unifying basic insights from linguistics and psycholinguistics with the currency of neural computation.

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Steiner, Donald F. "The Proinsulin C-peptide—A Multirole Model." Experimental Diabesity Research 5, no. 1 (2004): 7–14. http://dx.doi.org/10.1080/15438600490424389.

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The C-peptide links the insulin A and B chains in proinsulin, providing thereby a means to promote their efficient folding and assembly in the endoplasmic reticulum during insulin biosynthesis. It then facilitates the intracellular transport, sorting, and proteolytic processing of proinsulin into biologically active insulin in the maturing secretory granules of theβcells. These manifold functions impose significant constraints on the C-peptide structure that are conserved in evolution. After cleavage of proinsulin, the intact C-peptide is stored with insulin in the soluble phase of the secretory granules and is subsequently released in equimolar amounts with insulin, providing a useful independent indicator of insulin secretion. This brief review highlights many aspects of its roles in biosynthesis, as a prelude to consideration of its possible additional role(s) as a physiologically active peptide after its release with insulin into the circulation in vivo.

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VON BRECHT, JAMES H., DAVID UMINSKY, THEODORE KOLOKOLNIKOV, and ANDREA L. BERTOZZI. "PREDICTING PATTERN FORMATION IN PARTICLE INTERACTIONS." Mathematical Models and Methods in Applied Sciences 22, supp01 (April 2012): 1140002. http://dx.doi.org/10.1142/s0218202511400021.

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Large systems of particles interacting pairwise in d dimensions give rise to extraordinarily rich patterns. These patterns generally occur in two types. On one hand, the particles may concentrate on a co-dimension one manifold such as a sphere (in 3D) or a ring (in 2D). Localized, space-filling, co-dimension zero patterns can occur as well. In this paper, we utilize a dynamical systems approach to predict such behaviors in a given system of particles. More specifically, we develop a nonlocal linear stability analysis for particles uniformly distributed on a d - 1 sphere. Remarkably, the linear theory accurately characterizes the patterns in the ground states from the instabilities in the pairwise potential. This aspect of the theory then allows us to address the issue of inverse statistical mechanics in self-assembly: given a ground state exhibiting certain instabilities, we construct a potential that corresponds to such a pattern.

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Cahyati, Sally, and Daniel Rizky Mahendra. "DESIGN PROCESS OF DME STORAGE SYSTEM AS ASSEMBLY PARTS OR MAINTENANCE SPARE PARTS INVENTORY IN OFFSHORE OIL DRILLING PIPING SYSTEM." SINERGI 25, no. 1 (November 5, 2020): 19. http://dx.doi.org/10.22441/sinergi.2021.1.003.

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Discharge Manifold Equipment (DME) is an output pipe from a pump that bears an essential role in a piping system in offshore oil drilling, so it is a must to assure good bears condition whenever used. It is not an easy thing because DME is a significant and heavy component. Also, unfavourable conditions of offshore climate can accelerate its corrosion. Storage with the modular rack uses an offshore container certified DNV 2.7-1 / EN 12079 will be designed to fulfil those needs. The storage has an important role as an element in inventory, both the storage system for assembly parts or maintenance spare parts. This storage will be design using 4 (four) phases from VDI 2221 methods, namely; task clarification, conceptual design, embodiment design, and detailed design. Hydraulic power will be added to the system to support the piston movement so that the storage rack can be moved automatically by the hydraulic system. This storage has given the best solution for a systematic storing DME in the piping system of offshore oil drilling.

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Drain, Charles Michael, Joeseph T. Hupp, Kenneth S. Suslick, Michael R. Wasielewski, and Xin Chen. "A perspective on four new porphyrin-based functional materials and devices." Journal of Porphyrins and Phthalocyanines 06, no. 04 (April 2002): 243–58. http://dx.doi.org/10.1142/s1088424602000282.

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The tremendous potential for the manifold applications of porphyrins, porphyrazines, and phthalocyanines derives from their photophysical and electrochemical properties, their remarkable stability, and their predictable and rigid structure. These applications include nonlinear optics, catalysts, sensors, actuators, molecular sieves, and therapeutics. All of these properties are modulated by appending various chemical moieties onto the macrocycles, by choice of metallo derivative, and by the choice of environment. In multichromophoric systems, furthermore, the relative orientation of the chromophores, the nature of the linker, and the size of the system also dictate the properties. The synthesis of multichromophoric systems – both via covalent and noncovalent linkers – is driven by the desire to make new materials and to understand biological processes such as the various aspects of photosynthesis. Though electron and energy transfer processes continue to drive the synthesis of ever more complex systems, more recent focus has shifted toward other applications and functionalities of these structures. The focus of this perspective is on four recent developments in formation and characterization of functional, porphyrinic materials and devices: (1) self-assembly and self-organization of porphyrin arrays and aggregates into phototransistors and photonic devices; (2) self-assembled porphyrin squares for sensors, sieves, and catalysts; (3) covalently bound arrays of different chromophores as photonic materials; and (4) spatially separated arrays of metalloporphyrins as cross-reactive sensors.

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Jazaeri, Mohammad Javad, and John Andrews. "Design and Testing of a Modified Parallel Flow Field for Uniform Flow Distribution in PEMFuel Cells." Applied Mechanics and Materials 330 (June 2013): 693–97. http://dx.doi.org/10.4028/www.scientific.net/amm.330.693.

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The focus of this paper is to develop and test a modified design of the conventional parallel flow channel configuration in a proton exchange membrane (PEM) fuel cell. One of the main objectives in designing flow channel configurations is to achieve a uniform distribution of reactants across the catalyst layer of the membrane electrode assembly of the fuel cell. Uniform reactant distribution promotes an even current density distribution, and enhances power output and overall cell performance. A simple method for visualizing the flow distribution is used to study the flow distribution in the flow channels of a PEM fuel cell. In the experiment the principle of dimensional analysis and similitude was employed to study gas distribution by using water instead of gas. The results demonstrate that providing storage volumes before the channels creates a better flow distribution. The results also reveal that channels with the shortest distance between inlet and outlet manifold are reactant rich and are filled prior to the channels with longer such distances.

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Malins, Lara R., and Richard J. Payne. "Synthetic Amino Acids for Applications in Peptide Ligation–Desulfurization Chemistry." Australian Journal of Chemistry 68, no. 4 (2015): 521. http://dx.doi.org/10.1071/ch14568.

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Native chemical ligation is a powerful tool for the convergent assembly of homogeneous peptide and protein targets from unprotected peptide fragments. The method involves the chemoselective coupling of a peptide thioester with a peptide bearing an N-terminal cysteine (Cys) residue and is mediated by the nucleophilic Cys thiol functionality. A widely adopted extension of the technique for the disconnection of protein targets at alanine (Ala) ligation junctions has been the application of post-ligation desulfurization protocols for the mild removal of the Cys thiol moiety. Recently, attention has turned to the construction of synthetic amino acid building blocks bearing suitably positioned β-, γ-, or δ-thiol ligation auxiliaries with a view to expanding the scope of the ligation–desulfurization manifold. To date, several thiol-derived amino acids have been prepared, greatly increasing the generality and flexibility of chemoselective ligation technologies for the chemical synthesis of diverse protein targets. This review will highlight the current synthetic approaches to these important amino acid building blocks.

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Ortuño, Rosa M. "Carbocycle-Based Organogelators: Influence of Chirality and Structural Features on Their Supramolecular Arrangements and Properties." Gels 7, no. 2 (May 1, 2021): 54. http://dx.doi.org/10.3390/gels7020054.

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The rational design and engineer of organogel-based smart materials and stimuli-responsive materials with tuned properties requires the control of the non-covalent forces driving the hierarchical self-assembly. Chirality, as well as cis/trans relative configuration, also plays a crucial role promoting the morphology and characteristics of the aggregates. Cycloalkane derivatives can provide chiral chemical platforms allowing the incorporation of functional groups and hydrophobic structural units able for a convenient molecular stacking leading to gels. Restriction of the conformational freedom imposed by the ring strain is also a contributing issue that can be modulated by the inclusion of flexible segments. In addition, donor/acceptor moieties can also be incorporated favoring the interactions with light or with charged species. This review offers a perspective on the abilities and properties of carbocycle-based organogelators starting from simple cycloalkane derivatives, which were the key to establish the basis for an effective self-assembling, to sophisticated polycyclic compounds with manifold properties and applications.

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Rode, Sebastian, Jens Elgeti, and Gerhard Gompper. "Chiral-filament self-assembly on curved manifolds." Soft Matter 16, no. 46 (2020): 10548–57. http://dx.doi.org/10.1039/d0sm01339k.

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Chiral proteins can assemble as twisted ribbons on curved surfaces. Simulations of anisotropic building blocks on a cylindrical surface show a helical assembly with a preferred helix angle, and a power-law growth of the filament length in time.

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Yang, Chen, Liu Yuan, Ruimin Zhou, Zhen Wang, Jianqi Zhang, Yajie Zhang, Kun Lu, and Zhixiang Wei. "Effect of Side-Chain Variation on Single-Crystalline Structures for Revealing the Structure–Property Relationships of Organic Solar Cells." Organic Materials 02, no. 01 (January 2020): 026–32. http://dx.doi.org/10.1055/s-0039-3402514.

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The molecular stacking assembly in the active layer plays a significant role in the photovoltaic performance of organic solar cells (OSCs). Here, we report two new small molecular donors with different side chains, FBT-O and FBT-H, and their corresponding fullerene-based OSCs. A slight change in the side chains led to a big difference in the power conversion efficiencies (PCEs). Although the molecular structures of the two donors are similar to each other, PCEs of the devices based on FBT-O were almost three times higher than those of the devices based on FBT-H, with manifold short-circuit current density, fill factor, as well as three orders of magnitude enhancement in the hole mobility. The difference in their single crystal structures was thoroughly investigated, whereby the FBT-O exhibited better planarity leading to appropriate phase separation and domain size. Furthermore, two-dimensional grazing-incidence wide-angle X-ray scattering results of the blend films revealed that the two donors retained a similar stacking structure as compared to the single-crystal structures, thus, establishing a clear relationship between the molecular stacking structure and the device performance.

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Govindarasu, R., and S. Somasundaram. "Studies on Influence of Cell Temperature in Direct Methanol Fuel Cell Operation." Processes 8, no. 3 (March 19, 2020): 353. http://dx.doi.org/10.3390/pr8030353.

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Directmethanol fuel cells (DMFCs) offer one of the most promising alternatives for the replacement of fossil fuels. A DMFC that had an active Membrane Electrode Assembly (MEA) area of 45 cm2, a squoval-shaped manifold hole design, and a Pt-Ru/C catalyst combination at the anode was taken for analysis in simulation and real-time experimentation. A mathematical model was developed using dynamic equations of a DMFC. Simulation of a DMFC model using MATLAB software was carried out to identify the most influencing process variables, namely cell temperature, methanol flow rate and methanol concentration during a DMFC operation. Simulation results were recorded and analyzed. It was observed from the results that the cell temperature was the most influencing process variable in the DMFC operation, more so than the methanol flow rate and the methanol concentration. In the DMFC, real-time experimentation was carried out at different cell temperatures to find out the optimum temperature at which maximum power density was obtained. The results obtained in simulation and the experiment were compared and it was concluded that the temperature was the most influencing process variable and 333K was the optimum operating temperature required to achieve the most productive performance in power density of the DMFC.

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Kalluri, Lohitha, Bernard Seale, Megha Satpathy, Josephine F. Esquivel-Upshaw, and Yuanyuan Duan. "Three-Dimensional Finite Element Analysis of the Veneer—Framework Thickness in an All-Ceramic Implant Supported Fixed Partial Denture." Ceramics 4, no. 2 (April 28, 2021): 199–207. http://dx.doi.org/10.3390/ceramics4020015.

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This study was performed as an adjunct to an existing clinical study to validate the effect of veneer: framework thickness ratio on stress distribution in an implant-supported all-ceramic fixed partial denture. Two commercially available titanium dental implants with corresponding customized abutments and a patient-retrieved all-ceramic fixed partial denture were scanned using a high-resolution micro-CT scanner. Reconstructed 3D objects, along with a simulated bone surface, were incorporated into a non-manifold assembly and meshed simultaneously using Simpleware software (Synopsys Simpleware ScanIP Version P-2019.09; Mountain View, CA). Three such volume meshes (Model A, Model B, Model C) corresponding to veneer: framework thickness ratios of 3:1, 1:1, and 1:3 respectively were created, and exported to a finite element analysis software (ABAQUS). An axial load of 110 N was applied uniformly on the occlusal surfaces to calculate the static stresses and contour plots were generated in the post-processing module. From the data obtained, we observed optimum stress distribution in Model B. Also, the tensile stresses were concentrated in the posterior connector region of the prosthesis in all three models tested. Within the limitations of this study, we can conclude that equal thickness of veneer and framework layers would aid in better stress distribution.

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Lychev, S. A., T. N. Lycheva, and K. G. Koifman. "The Nonlinear evolutionary problem for self-stressed multilayered hyperelastic spherical bodies." PNRPU Mechanics Bulletin, no. 1 (December 15, 2020): 43–59. http://dx.doi.org/10.15593/perm.mech/2020.1.04.

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The present paper studies the evolutionary problem for self-stressed multilayered spherical shells. Their stress-strain state is characterized by incompatible local finite deformations that arise due to the geometric incompatibility of the stress-free shapes of the individual layers with each other. In the considered problem, these shapes are thin-walled hollow balls that cannot be assembled into a single solid without gaps or overlaps. Such an assembly is possible only with the preliminary deformations of individual layers, which cause self-balanced stresses in them. For multilayered structures with a large number of layers, a smoothing procedure is proposed, as a result of which the piecewise continuous functions defining the preliminary deformation of the layers are replaced by continuous distributions. The reference stress-free shape of a body constructed in this way is defined within the framework of geometric continuum mechanics as a manifold with a non-Euclidean (material) connection. For the problem in question, this connection is determined by the metric tensor and its deviation from the Euclidean connection is characterized by the scalar curvature. Generalized representations for Cauchy and Piola stresses are also obtained by the methods of geometric continuum mechanics. Computations, provided for the discrete structure and body with a non-Euclidean reference shape defined by the approximation of deformation parameters, numerically illustrate the convergency of the solution for the discrete model to corresponded solution for the continuous problem if the number of layers is increasing while their total thickness is constant. In modelling it is assumed that the material of the layers is compressible, homogeneous, hyperelastic, and determined by the first-order Mooney - Rivlin elastic potential. Individual layerwise finite deformations are supposed to be centrally symmetric.

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Schwanke, Hella, Markus Stempel, and Melanie M. Brinkmann. "Of Keeping and Tipping the Balance: Host Regulation and Viral Modulation of IRF3-Dependent IFNB1 Expression." Viruses 12, no. 7 (July 7, 2020): 733. http://dx.doi.org/10.3390/v12070733.

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The type I interferon (IFN) response is a principal component of our immune system that allows to counter a viral attack immediately upon viral entry into host cells. Upon engagement of aberrantly localised nucleic acids, germline-encoded pattern recognition receptors convey their find via a signalling cascade to prompt kinase-mediated activation of a specific set of five transcription factors. Within the nucleus, the coordinated interaction of these dimeric transcription factors with coactivators and the basal RNA transcription machinery is required to access the gene encoding the type I IFN IFNβ (IFNB1). Virus-induced release of IFNβ then induces the antiviral state of the system and mediates further mechanisms for defence. Due to its key role during the induction of the initial IFN response, the activity of the transcription factor interferon regulatory factor 3 (IRF3) is tightly regulated by the host and fiercely targeted by viral proteins at all conceivable levels. In this review, we will revisit the steps enabling the trans-activating potential of IRF3 after its activation and the subsequent assembly of the multi-protein complex at the IFNβ enhancer that controls gene expression. Further, we will inspect the regulatory mechanisms of these steps imposed by the host cell and present the manifold strategies viruses have evolved to intervene with IFNβ transcription downstream of IRF3 activation in order to secure establishment of a productive infection.

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Ševera, Pavol, and Michal Širaň. "Integration of Differential Graded Manifolds." International Mathematics Research Notices 2020, no. 20 (February 15, 2019): 6769–814. http://dx.doi.org/10.1093/imrn/rnz004.

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Abstract We consider the problem of integration of $L_\infty $-algebroids (differential non-negatively graded manifolds) to $L_\infty $-groupoids. We first construct a “big” Kan simplicial manifold (Fréchet or Banach) whose points are solutions of a (generalized) Maurer–Cartan equation. The main analytic trick in our work is an integral transformation sending the solutions of the Maurer–Cartan equation to closed differential forms. Following the ideas of Ezra Getzler, we then impose a gauge condition that cuts out a finite-dimensional simplicial submanifold. This “smaller” simplicial manifold is (the nerve of) a local Lie $\ell $-groupoid. The gauge condition can be imposed only locally in the base of the $L_\infty $-algebroid; the resulting local $\ell $-groupoids glue up to a coherent homotopy, that is, we get a homotopy coherent diagram from the nerve of a good cover of the base to the (simplicial) category of local $\ell $-groupoids. Finally, we show that a $k$-symplectic differential non-negatively graded manifold integrates to a local $k$-symplectic Lie $\ell$-groupoid; globally, these assemble to form an $A_\infty$-functor. As a particular case for $k=2$, we obtain integration of Courant algebroids.

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Polizzi, Nicholas F., Ting Jiang, David N. Beratan, and Michael J. Therien. "Engineering opposite electronic polarization of singlet and triplet states increases the yield of high-energy photoproducts." Proceedings of the National Academy of Sciences 116, no. 29 (June 10, 2019): 14465–70. http://dx.doi.org/10.1073/pnas.1901752116.

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Efficient photosynthetic energy conversion requires quantitative, light-driven formation of high-energy, charge-separated states. However, energies of high-lying excited states are rarely extracted, in part because the congested density of states in the excited-state manifold leads to rapid deactivation. Conventional photosystem designs promote electron transfer (ET) by polarizing excited donor electron density toward the acceptor (“one-way” ET), a form of positive design. Curiously, negative design strategies that explicitly avoid unwanted side reactions have been underexplored. We report here that electronic polarization of a molecular chromophore can be used as both a positive and negative design element in a light-driven reaction. Intriguingly, prudent engineering of polarized excited states can steer a “U-turn” ET—where the excited electron density of the donor is initially pushed away from the acceptor—to outcompete a conventional one-way ET scheme. We directly compare one-way vs. U-turn ET strategies via a linked donor–acceptor (DA) assembly in which selective optical excitation produces donor excited states polarized either toward or away from the acceptor. Ultrafast spectroscopy of DA pinpoints the importance of realizing donor singlet and triplet excited states that have opposite electronic polarizations to shut down intersystem crossing. These results demonstrate that oppositely polarized electronically excited states can be employed to steer photoexcited states toward useful, high-energy products by routing these excited states away from states that are photosynthetic dead ends.

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Li, Zhiqiang, Houjun Sun, Hongjiang Wu, and Shuai Zhang. "An Ultra-Wideband Compact TR Module Based on 3-D Packaging." Electronics 10, no. 12 (June 15, 2021): 1435. http://dx.doi.org/10.3390/electronics10121435.

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This study presents a novel four-channel tile-type T/R module which achieves excellent performances in ultra-wideband (2–12 GHz) and integrates all circuits in a super-light (25 g) and compact (27.8 × 27.8 × 12 mm3) mechanical structure in active phased array systems. The key advancement of this T/R module was to choose a Ball Grid Array (BGA) as the vertical interconnection and bracing between High-Temperature Co-fired Ceramic (HTCC) substrates in order to achieve a high-integration 3-D structure. Exploiting the HTCC multilayer layout, this paper presents the design and development of an ultra-wideband, compact and light, high-output power, four-channel, dual-polarization Transmit/Receive (T/R) Module. In this module, microwave circuits and power control circuits are highly integrated into electrically isolated HTCC layers or substrates, resulting in low coupling and crosstalk between signals. Furthermore, multichip assembly technology, multifunctional MMICs, and other high-integration technologies were adopted for this module. Each channel could provide more than 2 W transmit output power, more than 15 dB receive gain, and less than 5 dB receive noise figure. Every module contains four channels. The power supply and phase/amplitude conditioning of each channel can be controlled individually and showed good consistency of the amplitude and phase of all channels. The connectors of manifold port and polarization ports are all SSMP, which can achieve further integration. This module has also an automatic negative power protection function. The module has stabilized performance and mass production prospects.

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Bailly, David, Markus Bambach, Gerhard Hirt, Thorsten Pofahl, Giovanni Della Puppa, and Martin Trautz. "Flexible Manufacturing of Double-Curved Sheet Metal Panels for the Realization of Self-Supporting Freeform Structures." Key Engineering Materials 639 (March 2015): 41–48. http://dx.doi.org/10.4028/www.scientific.net/kem.639.41.

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Product development is complex due to the manifold requirements resulting from various perspectives, such as design, production, safety and sales. A concurrent engineering (CE) approach permits to respect all perspectives in the early development stage. However, in the architecture and construction sector for example, CE is particularly difficult to realize, because the central steering for this collaboration process is missing. Thus, the application of CE in the research sector can promote technical progress and cost reduction. In the specific field of freeform architecture, in most cases an individual shape of single components is unavoidable and the use of standard components impossible. Due to missing universal and mature construction concepts for freeform buildings, they are mostly realized with customized solutions often including material-consuming substructures, while the visible skin has only limited structural and functional properties.In this context the present paper proposes a novel universal panel system made of double-curved sheet metal layers enabling the assembly of self-supporting lightweight structures for the realization of freeform surfaces. The panel system has been developed in cooperation of architects, construction and production engineers, successfully applying an interdisciplinary CE approach. As a result, the concept allows for material and cost efficient solutions applicable for a wide range of freeform applications. The detailed development of the panel system is still in progress.Besides the general panel concept, the paper presents in particular the corresponding manufacturing chain and the tooling concept. Accounting for the varying part geometries in this application a flexible manufacturing chain based on the combination of stretch forming and incremental sheet forming has been developed. The entire production process is implemented in a single machine setup and successfully tested on a small-scale prototype.

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Biederstadt, K. C. "HYDRAULIC JET PUMPING AT TINTABURRA OILFIELD." APPEA Journal 28, no. 1 (1988): 19. http://dx.doi.org/10.1071/aj87002.

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The Hutton zone of the Tintaburra oilfield has an active bottom water drive which necessitates high gross fluid production rates to enable reserves to be produced within a reasonable period of time. A high volume artificial lift system capable of producing 8 000 to 10 000 barrels of fluid per day (BFPD) from 6 producing wells formed the basic design criteria, and hydraulic jet pumping was chosen as the means of artificial lift. The hydraulic jet pumping installation at Tintaburra was the first of its kind in Australia.The basic principle of operation of a jet pump is the transfer of momentum from a power fluid to reservoir fluid. The power fluid is pumped through a nozzle and the corresponding increase in velocity results in a pressure drop at the nozzle exit. This drop in pressure provides the drawdown necessary to move reservoir fluid to the pump where it is entrained and mixed with the power fluid. The combined stream is produced to surface and handled using convential production techniques. Equipment required in the Tintaburra system consists of a power fluid settling and storage tank, surface power fluid pump, distribution manifold, wellhead control valves and the subsurface assembly, including the jet pump itself.The application of mathematical equations describing jet pump operation was used in the initial selection of pumps for the Tintaburra wells. While this method provides insight into the operation of jet pumps, the use of equipment supplier's software proved to be more expedient in the final design stages and allowed many nozzle and throat combinations to be evaluated. Changes to well productivity brought about by the installation of down hole equipment required new pump selections for all wells. After nine months of operation, comprehensive production testing again highlighted changes to well productivity, necessitating variations in operating parameters or, in some cases, specification of new pumps.

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Rehman, Danish, Gian Morini, and Chungpyo Hong. "A Comparison of Data Reduction Methods for Average Friction Factor Calculation of Adiabatic Gas Flows in Microchannels." Micromachines 10, no. 3 (February 28, 2019): 171. http://dx.doi.org/10.3390/mi10030171.

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In this paper, a combined numerical and experimental approach for the estimation of the average friction factor along adiabatic microchannels with compressible gas flows is presented. Pressure-drop experiments are performed for a rectangular microchannel with a hydraulic diameter of 295 μ m by varying Reynolds number up to 17,000. In parallel, the calculation of friction factor has been repeated numerically and results are compared with the experimental work. The validated numerical model was also used to gain an insight of flow physics by varying the aspect ratio and hydraulic diameter of rectangular microchannels with respect to the channel tested experimentally. This was done with an aim of verifying the role of minor loss coefficients for the estimation of the average friction factor. To have laminar, transitional, and turbulent regimes captured, numerical analysis has been performed by varying Reynolds number from 200 to 20,000. Comparison of numerically and experimentally calculated gas flow characteristics has shown that adiabatic wall treatment (Fanno flow) results in better agreement of average friction factor values with conventional theory than the isothermal treatment of gas along the microchannel. The use of a constant value for minor loss coefficients available in the literature is not recommended for microflows as they change from one assembly to the other and their accurate estimation for compressible flows requires a coupling of numerical analysis with experimental data reduction. Results presented in this work demonstrate how an adiabatic wall treatment along the length of the channel coupled with the assumption of an isentropic flow from manifold to microchannel inlet results in a self-sustained experimental data reduction method for the accurate estimation of friction factor values even in presence of significant compressibility effects. Results also demonstrate that both the assumption of perfect expansion and consequently wrong estimation of average temperature between inlet and outlet of a microchannel can be responsible for an apparent increase in experimental average friction factor in choked flow regime.

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Chang, Stanley S., Steven Ferry, and Guoliang Yu. "Bounded rigidity of manifolds and asymptotic dimension growth." Journal of K-Theory 1, no. 1 (January 7, 2008): 129–44. http://dx.doi.org/10.1017/is007011012jkt008.

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AbstractWe provide a bounded rigidity result for uniformly contractible manifolds with bounded geometry and sufficiently slow asymptotic dimension growth. This notion of asymptotic growth is a generalization of Gromov's definition of asymptotic dimension. In particular for these manifolds we prove that the bounded assembly map is an isomorphism. Our result is inspired by the coarse Baum-Connes results of Yu and the development of squeezing structures.

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Skorek, Grzegorz. "Study of Losses and Energy Efficiency of Hydrostatic Drives with Hydraulic Cylinder." Polish Maritime Research 25, no. 4 (December 1, 2018): 114–28. http://dx.doi.org/10.2478/pomr-2018-0138.

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Abstract Energy efficiency of hydrostatic transmissions, and especially efficiencies of drives with motor speed controlled by throttle, as well as efficiency of hydraulic servomechanisms can in fact be higher than the efficiency values most frequently given by the respective literature in this field. With the progress achieved in recent years in the development of hydraulic systems it is becoming necessary to develop methods for precise energy efficiency calculation of such systems. It is difficult to imagine that more and more, better and better machines and control elements could be used without the possibility of a mathematical tool at our disposal to enable an accurate analysis and assessment of behavior of the system in which such machines and control elements have been applied. The paper discusses energy savings using mathematical model of losses in elements, the energy efficiency of the system. There are possibilities to reduce energy losses in proportional control systems (in the pump, in the throttle control unit, especially in the cylinder), and thus to improve the energy efficiency of the throttling manifold. The considerations allow for comparison of the loss power resulting from the applied hydraulic control structure of the hydraulic cylinder and the power consumed by the pump from the electric motor that drives it, the power necessary to provide pump-driven hydraulic cylinder. The article shows the impact on the output (useful) power consumed in the considered systems, and the impact on the power consumed of the loss power in the individual elements. The paper presents also formulas of loss power, formulas of energy efficiency connected with investigated hydrostatic drives, two schematic diagrams of hydraulic systems, their principle of operation and problems of studying losses in elements and energy efficiency characteristics of systems consisting of a feed assembly, control set and cylinder. It also includes a subject matter connected with an energy loss power of hydrostatic systems with hydraulic cylinder controlled by proportional directional control valve. Diagrams of loss power of two hydraulic systems worked at the same parameters of speed and load of a cylinder, which were different due to structure and ability of energy saving, were presented and compared.

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Fukaya, Tomohiro, and Shin-ichi Oguni. "Coronae of relatively hyperbolic groups and coarse cohomologies." Journal of Topology and Analysis 08, no. 03 (June 8, 2016): 431–74. http://dx.doi.org/10.1142/s1793525316500151.

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We construct a corona of a relatively hyperbolic group by blowing-up all parabolic points of its Bowditch boundary. We relate the [Formula: see text]-homology of the corona with the [Formula: see text]-theory of the Roe algebra, via the coarse assembly map. We also establish a dual theory, that is, we relate the [Formula: see text]-theory of the corona with the [Formula: see text]-theory of the reduced stable Higson corona via the coarse co-assembly map. For that purpose, we formulate generalized coarse cohomology theories. As an application, we give an explicit computation of the [Formula: see text]-theory of the Roe-algebra and that of the reduced stable Higson corona of the fundamental groups of closed 3-dimensional manifolds and of pinched negatively curved complete Riemannian manifolds with finite volume.

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Belegradek, Igor. "Aspherical manifolds, relative hyperbolicity, simplicial volume and assembly maps." Algebraic & Geometric Topology 6, no. 3 (September 20, 2006): 1341–54. http://dx.doi.org/10.2140/agt.2006.6.1341.

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Sitta, Christoph E., Frank Smallenburg, Raphael Wittkowski, and Hartmut Löwen. "Liquid crystals of hard rectangles on flat and cylindrical manifolds." Physical Chemistry Chemical Physics 20, no. 7 (2018): 5285–94. http://dx.doi.org/10.1039/c7cp07026h.

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Hambleton, Ian, and Alyson Hildum. "Topological 4-manifolds with right-angled Artin fundamental groups." Journal of Topology and Analysis 11, no. 04 (December 2019): 777–821. http://dx.doi.org/10.1142/s1793525319500328.

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We classify closed, spin[Formula: see text], topological [Formula: see text]-manifolds with fundamental group [Formula: see text] of cohomological dimension [Formula: see text] (up to [Formula: see text]-cobordism), after stabilization by connected sum with at most [Formula: see text] copies of [Formula: see text]. In general, we must also assume that [Formula: see text] satisfies certain [Formula: see text]-theory and assembly map conditions. Examples for which these conditions hold include the torsion-free fundamental groups of [Formula: see text]-manifolds and all right-angled Artin groupswhose defining graphs have no [Formula: see text]-cliques.

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Mahmoudi, Ghodrat, Marjan Abedi, Simon E. Lawrence, Ennio Zangrando, Maria G. Babashkina, Axel Klein, Antonio Frontera, and Damir A. Safin. "Tetrel Bonding and Other Non-Covalent Interactions Assisted Supramolecular Aggregation in a New Pb(II) Complex of an Isonicotinohydrazide." Molecules 25, no. 18 (September 4, 2020): 4056. http://dx.doi.org/10.3390/molecules25184056.

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A new supramolecular Pb(II) complex [PbL(NO2)]n was synthesized from Pb(NO3)2, N’-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and NaNO2. [PbL(NO2)]n is constructed from discrete [PbL(NO2)] units with an almost ideal N2O3 square pyramidal coordination environment around Pb(II). The ligand L− is coordinated through the 2-pyridyl N-atom, one aza N-atom, and the carbonyl O-atom. The nitrite ligand binds in a κ2-O,O coordination mode through both O-atoms. The Pb(II) center exhibits a hemidirected coordination geometry with a pronounced coordination gap, which allows a close approach of two additional N-atoms arising from the N=C(O) N-atom of an adjacent molecule and from the 4-pyridyl N-atom from the another adjacent molecule, yielding a N4O3 coordination, constructed from two Pb–N and three Pb–O covalent bonds, and two Pb⋯N tetrel bonds. Dimeric units in the structure of [PbL(NO2)]n are formed by the Pb⋯N=C(O) tetrel bonds and intermolecular electrostatically enforced π+⋯π− stacking interactions between the 2- and 4-pyridyl rings and further stabilized by C–H⋯π intermolecular interactions, formed by one of the methyl H-atoms and the 4-pyridyl ring. These dimers are embedded in a 2D network representing a simplified uninodal 3-connected fes (Shubnikov plane net) topology defined by the point symbol (4∙82). The Hirshfeld surface analysis of [PbL(NO2)] revealed that the intermolecular H⋯X (X = H, C, N, O) contacts occupy an overwhelming majority of the molecular surface of the [PbL(NO2)] coordination unit. Furthermore, the structure is characterized by intermolecular C⋯C and C⋯N interactions, corresponding to the intermolecular π⋯π stacking interactions. Notably, intermolecular Pb⋯N and, most interestingly, Pb⋯H interactions are remarkable contributors to the molecular surface of [PbL(NO2)]. While the former contacts are due to the Pb⋯N tetrel bonds, the latter contacts are mainly due to the interaction with the methyl H-atoms in the π⋯π stacked [PbL(NO2)] molecules. Molecular electrostatic potential (MEP) surface calculations showed marked electrostatic contributions to both the Pb⋯N tetrel bonds and the dimer forming π+⋯π− stacking interactions. Quantum theory of atoms in molecules (QTAIM) analyses underlined the tetrel bonding character of the Pb⋯N interactions. The manifold non-covalent interactions found in this supramolecular assembly are the result of the proper combination of the polyfunctional multidentate pyridine-hydrazide ligand and the small nitrito auxiliary ligand.

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Murray, Andrew P., François Pierrot, Pierre Dauchez, and J. Michael McCarthy. "A planar quaternion approach to the kinematic synthesis of a parallel manipulator." Robotica 15, no. 4 (July 1997): 361–65. http://dx.doi.org/10.1017/s0263574797000441.

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In this paper we present a technique for designing planar parallel manipulators with platforms capable of reaching any number of desired poses. The manipulator consists of a platform connected to ground by RPR chains. The set of positions and orientations available to the end-effector of a general RPR chain is mapped into the space of planar quaternions to obtain a quadratic manifold. The coefficients of this constraint manifold are functions of the locations of the base and platform R joints and the distance between them. Evaluating the constraint manifold at each desired pose and defining the limits on the extension of the P joint yields a set of equations. Solutions of these equations determine chains that contain the desired poses as part of their workspaces. Parallel manipulators that can reach the prescribed workspace are assembled from these chains. An example shows the determination of three RPR chains that form a manipulator able to reach a prescribed workspace.

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Journal articles on the topic 'Manifold assembly'

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