Selective DNA attachment of micro- and nanoscale particles to substrates

2002 ◽  
Vol 17 (2) ◽  
pp. 473-478 ◽  
Author(s):  
D. M. Hartmann ◽  
M. Heller ◽  
S. C. Esener ◽  
D. Schwartz ◽  
G. Tu
Keyword(s):  
Mechanical Properties ◽  
Solid Supports ◽  
Particulate Materials ◽  
Nanoscale Particles ◽  
Large Particles ◽  
Dna Strands ◽  
Dna Attachment

Materials formed from micro- and nanoscale particles are of interest because they often exhibit novel optical, electrical, magnetic, chemical, or mechanical properties. In this work, a means of constructing particulate materials using DNA strands to selectively attach micro- and nanoparticles to substrates was demonstrated. Unlike previous schemes, the DNA was anchored covalently to the particles and substrates, rather than through protein intermediaries. Highly reproducible selective attachment of 0.11–0.87 mm-diameter particles was achieved, with selective:nonselective binding ratios >20:1. Calculations showed that at most 350 and 4200 DNA strands were involved in the binding of the small and large particles, respectively. Experiments showed that the DNA was bent at an angle, relative to the surfaces of their solid supports.

scholarly journals Effects of the Nanostructured Fe-V-Nb Modificators on the Microstructure and Mechanical Properties of Si-Mn Steel

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Tiebao Wang ◽  
Chunxiang Cui ◽  
Kuo Jia ◽  
Lichen Zhao
Keyword(s):  
Mechanical Properties ◽  
Microalloyed Steel ◽  
Fracture Morphology ◽  
Rapid Quenching ◽  
Tem Analysis ◽  
Nanoscale Particles ◽  
Microstructure And Mechanical Properties ◽  
Nucleation Sites ◽  
Mn Steel ◽  
Better Than

The nanostructured Fe-V-Nb master alloy was prepared in vacuum rapid quenching furnace and then was added in the steel melts as modificators before casting. Next, the effects of the nanostructured Fe-V-Nb modificators on the microstructure and mechanical properties of the steel were studied. The results show that the grain size of the steel has been effectively refined, which is mainly because the dispersed nanoscale particles can produce more nucleation sites during the solidification of the liquid steel. Tensile properties and fracture morphology reveal that the yield strength and toughness of the steel modified by nanostructured Fe-V-Nb modificators are better than that of the microalloyed steel. TEM analysis shows that vanadium and niobium in the modificators exist in the form of (V, Nb) C which effectively increases the nucleation rate and leads to better mechanical properties of the steel.

Microstructure Characterization and Mechanical Properties of a Zn and Rare Earth Modified Mg Alloy

2015 ◽  
Vol 727-728 ◽  
pp. 111-114 ◽  
Author(s):  
Li Yuan Sheng ◽  
Fang Yang ◽  
Ting Fei Xi
Keyword(s):  
Mechanical Properties ◽  
Cast Alloy ◽  
Hot Extrusion ◽  
Eutectic Structure ◽  
Crystal Defects ◽  
Treatment Results ◽  
Nanoscale Particles ◽  
Residual Phase ◽  
Heat Treated ◽  
The Matrix

In the present paper, the Mg-Zn-Y-Nd alloy is fabricated by as casting and hot extrusion. Microstructure and mechanical properties of the as-cast, heat treated and hot extruded alloys are investigated. The results exhibit that Mg24Y5 phase with eutectic structure forms in the as-cast alloy, which has an orientation relationship with matrix of . The precipitating phase separates the matrix semi-continuously. The heat treatment results in most precipitates solid soluted into matrix, but there are still some nanoscale particles and residual phase along grain boundary. The hot extrusion refines the microstructure and leads to the formation of stacking faults in the matrix. Compared with the as-cast and heat treated alloy, the hot extruded alloy obtain great improvement in mechanical properties, which should be attributed to the grain refinement, solid solution and fomation of crystal defects

scholarly journals Optimization of a Solution Treatment in the Al-Cu-Mg-Ag Alloy via a Microstructural Investigation

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 66
Author(s):  
Hyeongsub So ◽  
Jae-Hong Shin ◽  
Leeseung Kang ◽  
Chanuk Jeong ◽  
Kyou-Hyun Kim
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Grain Growth ◽  
Microstructural Evolution ◽  
Precipitation Hardening ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Al Alloy ◽  
Microstructural Investigation ◽  
Large Particles

We investigated the effect of solution temperature (Tsol. = 440–530 °C) on the mechanical properties of the Al–3.4Cu–0.34Mg–0.3Mn–0.17Ag alloy, finding that the investigated Al alloy showed the highest mechanical strength of σUTS = ~329 MPa at a Tsol. value of 470 °C. The microstructural investigation demonstrates that the mechanical properties for different Tsol. values stem from grain growth, precipitation hardening, and the formation of large particles at the grain boundaries. On the basis of Tsol. = 470 °C, the effect of each microstructural evolution is significantly different on the mechanical properties. In this study, the relationships between the microstructural evolution and the mechanical properties were investigated with respect to different values of Tsol.

DNA Nanotechnologies for the Design of Bio-Inspired Soft Nanocomposites With Reversible Rigidity

2019 ◽  
Author(s):  
Theo Calais ◽  
Thileepan Stalin ◽  
Vincent S. Joseph ◽  
Pablo Valdivia y Alvarado
Keyword(s):  
Mechanical Properties ◽  
Dna Hybridization ◽  
Limited Range ◽  
Robot Locomotion ◽  
Dna Oligonucleotides ◽  
Dna Strands ◽  
Shape Memory Effects ◽  
Order Of Magnitude ◽  
Helicoidal Structure ◽  
Novel Strategy

Abstract Structures and mechanisms in soft robotics are primarily based on chemically versatile species such as hydrogels, polymers, or elastomers, thus offering great potential for the design of adaptive core properties. In particular, tunable rigidity is highly desirable to enable control of soft grippers or for advanced robot locomotion. However, most of the strategies explored so far rely on mechanisms, such as phase transitions or shape memory effects, that require heavy external hardware or have a limited range of tunable rigidity. In this work, we propose a novel strategy inspired by the sea cucumber dermis mechanism. High aspect ratio carbon nanotubes (CNTs) are reversibly interconnected by DNA oligonucleotides within a polyacrylamide (PAAm) hydrogel. The combination of the excellent mechanical properties of CNTs and the reversible hybridization of DNA strands into a stable double-helicoidal structure allowed the reversible tunability of mechanical properties over one order of magnitude (from ∼100 Pa to ∼1 kPa) within minutes by increasing the temperature beyond the melting temperature of DNA strands (∼50 °C). First, the functionalization strategy of CNTs with DNA strands is described and characterized. The aggregation of CNTs driven by the DNA hybridization is then demonstrated. The mechanical properties of hydrogels functionalized with CNTs are finally analyzed using rheology measurements.

Mechanical Properties of a Reversible, DNA-Crosslinked Polyacrylamide Hydrogel

2004 ◽  
Vol 126 (1) ◽  
pp. 104-110 ◽  
Author(s):  
David C. Lin ◽  
Bernard Yurke ◽  
Noshir A. Langrana
Keyword(s):  
Mechanical Properties ◽  
Crosslink Density ◽  
Characteristic Temperature ◽  
Polyacrylamide Hydrogel ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Dna Crosslinks ◽  
Dna Strands ◽  
Dna Strand ◽  
Dependent Viscosity

Mechanical properties of a polyacrylamide gel with reversible DNA crosslinks are presented. In this system, three DNA strands replace traditional chemical crosslinkers. In contrast to thermoset chemically crosslinked polyacrylamide, the new hydrogel is thermoreversible; crosslink dissociation without the addition of heat is also feasible by introducing a specific removal DNA strand. This hydrogel is characterized by a critical crosslink concentration at which gelation occurs. Below the critical point, a characteristic temperature exists at which a transition in viscosity is observed. Both temperature-dependent viscosity and elastic modulus of the material are functions of crosslink density.

DISPERSION AND MECHANICAL PROPERTIES OF CERIUM OXIDE FILLED INTO RUBBER COMPOSITES

2014 ◽  
Vol 87 (2) ◽  
pp. 340-347 ◽  
Author(s):  
Zhaogang Liu ◽  
Mei Li ◽  
Yanhong Hu ◽  
Hai Fu ◽  
Mitang Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cerium Oxide ◽  
Rubber Matrix ◽  
X Ray Diffraction ◽  
Small Particles ◽  
Rubber Composites ◽  
X Ray ◽  
Large Particles ◽  
Better Than ◽  
Properties Of Composites

ABSTRACT Rubber composites were synthesized by natural rubber filled with cerium oxide with different particle diameters. The dispersion morphology of cerium oxide in rubber matrix and the mechanical properties of composites were studied, and the contrast experiment of reinforcing rubber with cerium oxide was performed. The results showed that the small particles of cerium oxide had better disparity than the large particles of cerium oxide in NR. The mechanical properties of rubber filled with small particles of cerium oxide were better than those of rubber filled with large particles of cerium oxide. The crystalline rubber was measured by X-ray diffraction, which indicated that the CeO2 accelerated crystallization capacity and confined the rubber chain movement. The tensile strength of rubber was increased by this confinement.

Microstructure and Mechanical Properties of a Single Crystal NiAl Alloy with Zr or HF Rich G-Phase Precipitates.

1990 ◽  
Vol 213 ◽  
Author(s):  
I. E. Locci ◽  
R. D. Noebe ◽  
R. R. Bowman ◽  
R. V. Miner ◽  
M. V. Nathal ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Heat Treatments ◽  
Strengthening Effect ◽  
Slow Cooling ◽  
Large Plate ◽  
Nial Alloy ◽  
Large Particles ◽  
The Matrix

ABSTRACTThe possibility of producing NiAl reinforced with the G-phase (Ni16X6Si7), where X is Zr or Hf, has been investigated. The microstructures of these NiAl alloys have been characterized in the as-cast and annealed conditions. The G-phases are present as fine cuboidal precipitates (10 to 40 nm) and have lattice parameters almost four times that of NiAl. They are coherent with the matrix and fairly resistant to coarsening during annealing heat treatments. Segregation and non-uniform precipitate distribution observed in as-cast materials were eliminated by homogenization at temperatures near 1600 K. Slow cooling from these temperatures resulted in large plate shaped precipitates, denuded zones, and a loss of coherency in some of the large particles. Faster cooling produced a homogeneous fine distribution of cuboidal G-phase particles (≤10 nm) in the matrix. Preliminary mechanical properties for the Zr-doped alloy are presented and compared to binary single crystal NiAl. The presence of these precipitates appears to have an important strengthening effect at temperatures≥1000 K compared to binary NiAl single crystals.

Effect of Aging Condition on the Mechanical Properties of an Al-Cu-Mg-Ag Alloy

2012 ◽  
Vol 476-478 ◽  
pp. 42-45 ◽  
Author(s):  
Yan Xia Gu ◽  
Zhi Yi Liu ◽  
Di Er Yu ◽  
Xuan Wei Zhou ◽  
Qian Qian Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Room Temperature ◽  
Average Particle Size ◽  
Average Particle ◽  
Small Particles ◽  
Aging Condition ◽  
Elevated Temperature Tensile ◽  
Exposure Temperature ◽  
Large Particles

The effect of aging condition on elevated temperature tensile strength and microstructure of an Al-Cu-Mg-Ag alloy was investigated. The tensile strength of 165°C/14h samples was greater at room temperature and 200°C, while the 165°C/2h samples got superior tensile properties at 250°C and 300°C. The microstructure contained mainly of Ω plates in both conditions, and as the increasing of exposure temperature, the coarsening of Ω precipitates occurred by the solution of small particles and the growth of large particles, resulting in an increase in the average particle size, and the decrease in the number of precipitates.

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