A Method for Characterizing Elastic Structures in the Mid-Frequency Region

2004 ◽  
Author(s):  
W. Steve Shepard ◽  
Yi Liu
Keyword(s):  
Contact Region ◽  
Excitation Frequency ◽  
Building Blocks ◽  
Critical Parameters ◽  
Parameter Method ◽  
Elastic Structures ◽  
Pole Parameter ◽  
Potential Applications ◽  
Engine Mount ◽  
Spatially Varying

This work presents a method for characterizing elastic structures when spatially varying properties over the input and output contact regions are considered. Most analytical or experimental approaches, such as the four-pole parameter method, are limited by the inherent use of lumped quantities to represent critical parameters. When the excitation frequency increases, however, the structural wavelength becomes comparable to the dimensions of the contact region. As a result, the point-quantity assumption is no longer valid. To address this limitation, the work described here reformulates the traditional four-pole method in terms of quantities defined over planes. Consequently, spatial variations across the region connecting the structures can be considered. After the method is derived, it is applied to a simplified engine mount model in which two elastic beams are coupled through a set of elastic and inertial elements. Just like for the four-pole method, the formulation approach uses building blocks for simple structures that can be assembled to represent more complex structures. Some of the potential applications for this method are also discussed. By using this method, a meaningful characterization of the dynamic behavior can be obtained for structures when the frequency increases beyond that for which the point quantity approaches become invalid.

scholarly journals A Structurally Variable Hinged Tetrahedron Framework from DNA Origami

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
David M. Smith ◽  
Verena Schüller ◽  
Carsten Forthmann ◽  
Robert Schreiber ◽  
Philip Tinnefeld ◽  
...  
Keyword(s):  
Self Assembly ◽  
Gel Electrophoresis ◽  
Imaging Techniques ◽  
Building Blocks ◽  
Dna Origami ◽  
Microscopy Technique ◽  
Wire Frame ◽  
Wide Range ◽  
Potential Applications ◽  
Linker Molecules

Nanometer-sized polyhedral wire-frame objects hold a wide range of potential applications both as structural scaffolds as well as a basis for synthetic nanocontainers. The utilization of DNA as basic building blocks for such structures allows the exploitation of bottom-up self-assembly in order to achieve molecular programmability through the pairing of complementary bases. In this work, we report on a hollow but rigid tetrahedron framework of 75 nm strut length constructed with the DNA origami method. Flexible hinges at each of their four joints provide a means for structural variability of the object. Through the opening of gaps along the struts, four variants can be created as confirmed by both gel electrophoresis and direct imaging techniques. The intrinsic site addressability provided by this technique allows the unique targeted attachment of dye and/or linker molecules at any point on the structure's surface, which we prove through the superresolution fluorescence microscopy technique DNA PAINT.

Substantially Transparent Pt, Pd, Rh, And Re Films: Preparation and Properties

1987 ◽  
Vol 111 ◽  
Author(s):  
D. E. Aspnes ◽  
A. Heller
Keyword(s):  
Light Transmission ◽  
Building Blocks ◽  
Poor Quality ◽  
Model Calculations ◽  
Transmission Electron ◽  
Metal Volume ◽  
Potential Applications ◽  
Metallic Catalyst ◽  
Anomalous Transparency ◽  
Best Fit

AbstractFilms of Pt, Pd, Rh, and Re with metal volume fractions of 0.3 to 0.5 have been prepared by mass-transport-limited photoelectrodeposition onto (001) p-InP photocathodes from ∼5 × 10−5 M solutions of the metal ions in 1 M HClO4. These films exhibit their normal catalytic activities (e.g., in hydrogen evolution) and have normal crystal structures, yet are substantially more transparent than equivalent dense films of the same metal loading per unit area. Effective-medium analysis of the spectroellipsometrically measured dielectric functions of these films shows that the anomalous transparency is due to microstructure: depolarization factors and metal packing fractions obtained by best-fit model calculations indicate dendritic (Rh), particulate (Pt, Pd), or platelet (Re) forms that are poorly interconnected in directions parallel to the surface, and whose dimensions are all small compared to the wavelength of light. Transmission electron micrographs confirm these results and reveal that these films consist of primary building blocks of ca. 5 nm crystallites that are organized into relatively loosely packed secondary structures. Potential applications of these films include the formation of efficient metallic-catalyst-coated photoelectrodes on poor-quality semiconductors.

scholarly journals Cyclic cis-1,3-Diamines Derived from Bicyclic Hydrazines: Synthesis and Applications

Synlett ◽  
2020 ◽  
Author(s):  
Erica Benedetti ◽  
Laurent Micouin ◽  
Claire Fleurisson
Keyword(s):  
Bond Cleavage ◽  
Building Blocks ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Chemical Similarity ◽  
Active Compounds ◽  
General Overview ◽  
Biological Interest ◽  
Potential Applications ◽  
Rna Binders

AbstractCyclic cis-1,3-diamines are versatile building blocks frequently found in natural molecules or biologically active compounds. In comparison with widely studied 1,2-diamines, and despite their chemical similarity, 1,3-diamines have been investigated less intensively probably because of a lack of general synthetic procedures giving access to these compounds with good levels of chemo-, regio-, and stereocontrol. In this Account we will give a general overview of the biological interest of cyclic cis-1,3-diamines. We will then describe the synthesis and potential applications of these compounds with a particular focus on the work realized in our laboratory.1 Introduction2 Biological Relevance of the cis-1,3-Diamine Motif3 Classical Synthetic Strategies towards cis-1,3-Diamines4 N–N Bond Cleavage of Bicyclic Hydrazines: A Versatile Method to Access cis-1,3-Diamines4.1 Preparation of Five-Membered Cyclic cis-1,3-Diamino Alcohols4.2 Access to Fluorinated 1,3-cis-Diaminocyclopentanes4.3 Synthesis of cis-1,3-Diaminocyclohexitols4.4 Formation of Cyclic cis-3,5-Diaminopiperidines5 Applications of Cyclic cis-1,3-Diamines5.1 Small-Molecular RNA Binders5.2 Fluorinated 1,3-Diamino Cyclopentanes as NMR Probes6 Concluding Remarks

scholarly journals Recent Progress in the Synthesis and Characterization of Diarylethene-based MOFs

2014 ◽  
Vol 70 (a1) ◽  
pp. C1223-C1223
Author(s):  
Jason Benedict ◽  
Ian Walton ◽  
Dan Patel ◽  
Jordan Cox
Keyword(s):  
Chemical Properties ◽  
Building Blocks ◽  
Synthesis And Characterization ◽  
Next Generation ◽  
Design Synthesis ◽  
Thermally Induced ◽  
Potential Applications ◽  
External Stimuli ◽  
Physical And Chemical

Metal-organic Frameworks (MOFs) remain an extremely active area of research given the wide variety of potential applications and the enormous diversity of structures that can be created from their constituent building blocks. While MOFs are typically employed as passive materials, next-generation materials will exhibit structural and/or electronic changes in response to applied external stimuli including light, charge, and pH. Herein we present recent results in which advanced photochromic diarylethenes are combined with MOFs through covalent and non-covalent methods to create photo-responsive permanently porous crystalline materials. This presentation will describe the design, synthesis, and characterization of next-generation photo-switchable diarylethene based ligands which are subsequently used to photo-responsive MOFs. These UBMOF crystals are, by design, isostructural with previously reported non-photoresponsive frameworks which enables a systematic comparison of their physical and chemical properties. While the photoswitching of the isolated ligand in solution is fully reversible, the cycloreversion reaction is suppressed in the UBMOF single crystalline phase. Spectroscopic evidence for thermally induced cycloreversion will be presented, as well as a detailed analysis addressing the limits of X-ray diffraction techniques applied to these systems.

scholarly journals Biotechnology-Derived Chitosans with Non-Random Patterns of Acetylation Differ from Conventional Chitosans in Their Properties and Activities

2021 ◽  
Author(s):  
Jasper Wattjes ◽  
Sruthi Sreekumar ◽  
Anna Niehues ◽  
Tamara Mengoni ◽  
Ana Carina Loureiro Mendes ◽  
...  
Keyword(s):  
Biological Activities ◽  
Building Blocks ◽  
Degree Of Polymerization ◽  
Natural Process ◽  
Solution Properties ◽  
Potential Applications ◽  
Random Patterns

Chitosans are versatile biopolymers with multiple biological activities and potential applications. They are linear copolymers of glucosamine and N-acetylglucosamine defined by their degree of polymerization (DP), fraction of acetylation (<i>F<sub>A</sub></i>), and pattern of acetylation (PA). Technical chitosans produced chemically from chitin possess defined DP and FA but random PA, while enzymatically produced natural chitosans are likely to have non-random PA. This natural process has not been replicated using biotechnology because chitin de-N-acetylases do not efficiently deacetylate crystalline chitin. Here, we show that such enzymes can partially N-acetylate polyglucosamine in the presence of excess acetate, yielding chitosans with <i>F<sub>A</sub></i> up to 0.7 and an enzyme-dependent non-random PA. The biotech chitosans differ from technical chitosans both in terms of physicochemical and nanoscale solution properties and biological activities. As with synthetic block co-polymers, controlling the distribution of building blocks within the biopolymer chain will open a new dimension of chitosan research and exploitation.

Heat Conduction in Three Dimensional Stacked Packages

2005 ◽  
Author(s):  
Anand Desai ◽  
James Geer ◽  
Bahgat Sammakia
Keyword(s):  
Heat Conduction ◽  
Thermal Management ◽  
Heat Generation ◽  
Analytical Study ◽  
Three Dimensional ◽  
The Other ◽  
Heat Generation Rate ◽  
Potential Applications ◽  
Steady State Heat ◽  
Spatially Varying

This paper presents the results of an analytical study of steady state heat conduction in multiple rectangular domains. Any finite number of such domains may be considered in the current study. The thermal conductivity and thickness of these domains may be different. The entire geometry composed of these connected domains is considered as adiabatic on the lateral surfaces and can be subjected to uniform convective cooling at one end. The other end of the geometry may be adiabatic and a specified, spatially varying heat generation rate can be applied in each of the domains. The solutions are found to be in agreement with known solutions for simpler geometries. The analytical solution presented here is very general in that it takes into account the interface resistances between the layers. One application of this analytical study relates to the thermal management of a 3-D stack of devices and interconnect layers. Another possible application is to the study of hotspots in a chip stack with non uniform heat generation. Many other potential applications may also be simulated.

scholarly journals Controlled allylation of polyelectrolytes: a deep insight into chemical aspects and their applicability as building blocks for robust multilayer coatings

2019 ◽  
Vol 91 (6) ◽  
pp. 983-995
Author(s):  
Thi-Thanh-Tam Nguyen ◽  
Sabrina Belbekhouche ◽  
Rémi Auvergne ◽  
Benjamin Carbonnier ◽  
Daniel Grande
Keyword(s):  
Heterogeneous Reaction ◽  
Experimental Tests ◽  
Building Blocks ◽  
Water Soluble ◽  
Basic Solution ◽  
Solution Ph ◽  
Covalent Crosslinking ◽  
Electrolytic Properties ◽  
Potential Applications ◽  
Post Modification

Abstract Polyelectrolytes (PEs) bearing easily derivatizable functions for possible post-modification under mild conditions can find a broad range of applications in various fields. The present paper describes the successful controlled side-chain allylation of two types of PEs: polyamine-based polycations, i.e. poly(allylamine hydrochloride) (PAH) and branched polyethyleneimine (PEI), and strong polyanions, i.e. poly(sodium vinyl sulfonate) (PVS) and poly(sodium 4-styrene sulfonate) (PSS). PSS has been largely investigated in the literature, while PVS is much less commonly explored. The allylation of each type presents its own drawback, i.e. heterogeneous reaction in the case of strong polyanions and instability of partially protonated allylated polyamine products. Nevertheless, all encountered difficulties could be solved and thoroughly elucidated by different experimental tests. This partial allyl-functionalization does not affect the electrolytic properties of the newly allylated PEs, as evidenced by the effective construction of two series of polyelectrolyte multilayer (PEM) films, namely PEI-ene (PSS-ene/PAH-ene)4 and PEI-ene (PVS-ene/PAH-ene)4, the latter being one of the rare examples developed in the literature. The presence of allyl groups on the PE side-chains allows for the stabilization of the resulting PEM films via thiol-ene photo-crosslinking in the presence of a water-soluble dithiol crosslinker. In order to fix permanently the resulting crosslinked PEM films on substrates, the covalent crosslinking occurs not only between different C=C bonds on PE layers but also with those present on substrates preliminarily functionalized with allyl groups via sulfur–gold chemistry. The robustness of both resulting crosslinked PEM films under strongly basic solution (pH 14) is validated by Quartz Crystal Microbalance (QCM) measurements. The versatility and effectiveness of the present approach is expected to find potential applications in different scientific and technological fields.

Investigation of Phase Transformation and Structure Evolution of Electrospun Copper Oxide Nanofibers during Thermal Annealing

2011 ◽  
Vol 471-472 ◽  
pp. 792-797
Author(s):  
Dariush Jafar Khadem ◽  
Zahira Yaakob ◽  
Samaneh Shahgaldi ◽  
Wan Ramli Wan Daud ◽  
Edy Herianto Majlan
Keyword(s):  
Electron Microscopy ◽  
Copper Oxide ◽  
Sol Gel ◽  
Building Blocks ◽  
Structure Evolution ◽  
Gravimetric Analysis ◽  
Effective Parameters ◽  
Transmission Electron ◽  
Electrospinning Method ◽  
Potential Applications

One-dimensional nanostructures, like nanofibers, nanobelts, nanotubes, nanorods have been regarded as a new class of nanomaterials that have been attracted as the most promising building blocks for verity applications in the last few years. As one type of important structures with intensive research efforts have been devoted to the production and investigation of the metal oxides. Metal oxide nanofibers have different potential to play an essential role in a series of application such as optics, nanoelectronics, catalysts, sensors, storage, optoelectonics, and full cell. Copper oxide nanostructures is a promising semiconductor material with potential applications in photochemical, electrochemical, electrochromic especially in water splitting, catalysts, and fabrication of photovoltaic devices. In this paper electrospinning method via sol-gel was used to fabricate copper oxide nanofibers. Copper oxide nanofibers with different morphology were synthesized by different calcinations temperature. In this paper, effective parameters such as voltage, concentration of precursor and different calcinations temperature were characterized by thermal gravimetric analysis, scanning electron microscopy (SEM), Transmission electron microscopy, x-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR) and Brunauer Emmett and Teller (BET).

Bio based fuels and fuel additives from lignocellulose feedstock via the production of levulinic acid and furfural

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Geertje Dautzenberg ◽  
Mirko Gerhardt ◽  
Birgit Kamm
Keyword(s):  
Levulinic Acid ◽  
Cost Effective ◽  
Building Blocks ◽  
Fuel Additives ◽  
Secondary Products ◽  
Diesel Fuels ◽  
Lignocellulosic Feedstock ◽  
Chemical Pulping ◽  
Potential Applications ◽  
Lignocellulose Feedstock

Abstract The demand for biomass-derived fuels and fuel additives, particularly in the transportation sector, has stimulated intense research efforts in the chemistry of levulinic acid and levulinic acid secondary products over the past decade. Additionally, recent technological progress in lignocellulosic feedstock (LCF) chemistry has also increased attention in this regard. As a result, several oxygenating fuel additives with potential applications in both gasoline and diesel fuels have been identified. Some of the chemicals, such as ethyl valerate, appear to be viable alternatives to the currently used branched, short-chain ethers that are derived from side products of petrol refining. Cost-effective applications of lignocellulosic biomass are a crucial aspect of its feasibility. In consideration of the LCF biorefinery concept, the feasibility must also include the chemical pulping of LCF and the comprehensive utilisation of its main constituents cellulose, hemicelluloses, and lignin. The present study focuses on cellulose and hemicelluloses as viable sources for the production of biofuels and biofuel additives. Multifunctional catalysis, including hydrogenation and acid catalysis are the primary instruments used for the conversion of the monomeric carbohydrate building blocks, i.e., mainly C5 sugars, such as xylose and arabinose, and C6 sugars in the form of glucose and their respective secondary products, furfural and levulinic acid. Lignin utilisation is not addressed in this paper.

Size-dependent mechanical properties of twin graphene

2020 ◽  
pp. 239779142097255
Author(s):  
Fangyan Zhu ◽  
Jiantao Leng ◽  
Zhengrong Guo ◽  
Tienchong Chang
Keyword(s):  
Mechanical Properties ◽  
Fracture Strain ◽  
Building Blocks ◽  
Fracture Pattern ◽  
Uniaxial Tensile ◽  
Carbon Allotrope ◽  
Size Dependent ◽  
Potential Applications ◽  
Dynamics Simulations ◽  
Anisotropy Of Mechanical Properties

Twin Graphene, a novel 2D planar semiconducting carbon allotrope predicted recently, has attracted tremendous attention due to its potential applications in nano electromechanical systems (NEMS). In this paper, we use Molecular Dynamics simulations to investigate the mechanical properties of twin graphene. By performing uniaxial tensile loading, we find that the Young’s modulus, failure stress and fracture strain of a twin graphene sheet are strongly dependent on its size. Rectangular sheets show more apparent anisotropy of mechanical properties than square sheets. Our results also demonstrate that the fracture pattern of twin graphene is dependent on its geometry, as a result of its diverse bond types and orientations. These findings present an in-depth understanding of size dependent mechanical properties of twin graphene, and may benefit its future applications as building blocks of NEMS devices.

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