scholarly journals Nano-scale treatment for a macro-scale disease: nanoparticle-delivered siRNA silences CCR2 and treats myocarditis

2014 ◽  
Vol 36 (23) ◽  
pp. 1434-1436 ◽  
Author(s):  
L. T. Cooper ◽  
D. Fairweather
Keyword(s):  
Author(s):  
Angel G. Perez ◽  
Julie S. Linsey

There are countless products that perform the same function but are engineered to suit a different scale. Designers are often faced with the problem of taking a solution at one scale and mapping it to another. This frequently happens with design-by-analogy and bioinspired design. Despite various scaling laws for specific systems, there are no global principles for scaling systems, for example from a biological nano-scale to macro-scale. This is likely one of the reasons bioinspired design is difficult. Very often scaling laws assume the same physical principles are being used, but this study of products indicates that a variety of changes occur as scale changes, including changing the physical principles to meet a particular function. Empirical product research was used to determine a set of principles by observing and understanding numerous products to unearth new generalizations. The function a product performs is examined in various scales to view subtle and blatant differences. Principles are then determined. This study provides an initial step in creating new innovative designs based on existing solutions in nature or other products that occur at very different scales. Much further work is needed by studying additional products and bioinspired examples.


2019 ◽  
Vol 956 ◽  
pp. 332-341 ◽  
Author(s):  
Jia Fu

The performance prediction of C-S-H gel is critical to the theoretical research of cement-based materials. In the light of recent computational material technology, modeling from nano-scale to micro-scale to predict mechanical properties of structure has become research hotspots. This paper aims to find the inter-linkages between the monolithic "glouble" C-S-H at nano-scale and the low/high density C-S-H at the micro-scale by step to step method, and to find a reliable experimental verification method. Above all, the basic structure of tobermorite and the "glouble" C-S-H model at nano-scale are discussed. At this scale, a "glouble" C-S-H structure of about 5.5 nm3 was established based on the 11Å tobermorite crystal, and the elastic modulus ​​of the isotropic "glouble" is obtained by simulation. Besides, by considering the effect of porosity on the low/high density of the gel morphology, the C-S-H phase at micro-scale can be reversely characterized by the "glouble". By setting different porosities and using Self-Consistent and Mori-Tanaka schemes, elastic moduli of the low density and high density C-S-H ​​from that of "glouble" are predicted, which are used to compare with the experimental values of the outer and inner C-S-H. Moreover, the nanoindentation simulation is carried out, where the simulated P-h curve is in good agreement with the accurate experimental curve in nanoindentation experiment by the regional indentation technique(RET), thus the rationality of the "glouble" structure modeled is verified and the feasibility of Jennings model is proved. Finally, the studies from the obtained ideal "glouble" model to the C-S-H phase performance has realized the mechanical properties prediction of the C-S-H structure from nano-scale to micro-scale, which has great theoretical significance for the C-S-H structural strengthening research.


Author(s):  
Polina Prokopovich ◽  
Stephanos Theodossiades ◽  
Homer Rahnejat ◽  
Darren Hodson

In many drug dispensing devices, such as syringes and inhalers, a rubber ring is used as a seal. During device actuation the seal is subjected to friction which in turn causes it to deform. This can lead to suboptimal performance of the device and as a consequence variability in the delivered dose. Seal friction is complex, arising from adhesion of rubber in contact with a moving counterface, viscous action of a thin film of entrained fluid into the contact and ploughing of seal asperities. Therefore, the first step in the understanding of the conjunctional behaviour of rubber seals is the fundamental study of these friction mechanisms. A developed model can then be validated against measurements, prior to its use in a multi-body dynamic model of the inhaler valve to predict product performance, robustness and variability due to manufacturing tolerances. This paper undertakes two distinct studies. Firstly, a friction model for the rough elastomeric material, typically used for valve seals is developed. The model is then validated against measurements in nano-scale. Friction data is presented for nitrile rubber, using a silicon nitride AFM tip for nano-scale interactions. The validation is then extended to macro-scale motion of an instrumented trolley, incorporating an elastomeric surface sliding on a polymeric counterface. These tests are carried out for polybutylene terephthalate (PBT). Secondly, the validated friction model is used in an elastomeric seal model in-situ within the valve and in contact with a polymeric stem surface and subject to both global fittment deformation and canister pressure. Reasonable agreement is found between the measurements and model predictions for the nano-scale coefficient of friction of rubber against silicon nitride. Similarly, good agreement has been obtained for the mean coefficient of friction of rubber against PBT. In addition, the mechanism of adhesion between contacting surfaces of gasket and stem is taken into account.


Soft Matter ◽  
2018 ◽  
Vol 14 (26) ◽  
pp. 5420-5427 ◽  
Author(s):  
Fereshteh Samadi Taheri ◽  
Hossein Fazli ◽  
Masao Doi ◽  
Mehdi Habibi

Macro-scale experiment and nano-scale simulation of a chain/polymer show the same escape behavior through the pore in the wall in the presence of particles.


2021 ◽  
Vol 8 ◽  
Author(s):  
Shijun Wang ◽  
Amardeep Singh ◽  
Qiong Liu

Adding conductive materials to cement-based composites can lead to pressure-sensitive properties. In this study, different scales of conductive materials were incorporated, including macro-scale steel fibers, micro-scale carbon black powder, and nano-scale graphene. The coupling effect of three scales of materials ensured that the intelligent concrete had improved strength, lower cost, and comparable pressure-sensitive performance. The results show that the strength of intelligent concrete with multi-scale conductive materials is higher than that of the contrast group of ordinary concrete and intelligent concrete when adding nano-scale graphene alone. Especially, the addition of steel fibers significantly improved the crack resistance of the intelligent concrete. In the elastic stage, the resistivity of intelligent concrete of multi-scale conductive materials decreases with the increase in compression, and the decrease range of resistivity is approximately proportional to the external force. After reaching the peak load, the resistivity of the intelligent concrete gradually increases and can illustrate the damage evolution. This study lays a foundation for the application of intelligent concrete in deformation and damage monitoring.


2009 ◽  
Vol 15 (S3) ◽  
pp. 77-78 ◽  
Author(s):  
A. Pelaez-Vargas ◽  
N. Ferrell ◽  
M. H. Fernandes ◽  
D. Hansford ◽  
F. J. Monteiro

AbstractFrom a biomaterials perspective, it is now understood that success in the osseointegration of a dental implant is conditioned by its “macro”, “micro” and “nano” scale features. Macro-scale roughness is necessary to improve primary stabilization in the post-surgical phase inducing a peri-implant thin fibrous layer. However, the more complex process in the true cell-material interaction is dependent on micro and nano scale phenomena. There is clear evidence that cell adhesion, proliferation, organization and phenotype are modulated at the micro-scale and that protein absorption is fundamentally a process conditioned at nano-scale.


Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3500
Author(s):  
Dakota Piorkowski ◽  
Bo-Ching He ◽  
Sean J. Blamires ◽  
I-Min Tso ◽  
Deborah M. Kane

Adhesive materials used by many arthropods for biological functions incorporate sticky substances and a supporting material that operate synergistically by exploiting substrate attachment and energy dissipation. While there has been much focus on the composition and properties of the sticky glues of these bio-composites, less attention has been given to the materials that support them. In particular, as these materials are primarily responsible for dissipation during adhesive pull-off, little is known of the structures that give rise to functionality, especially at the nano-scale. In this study we used tapping mode atomic force microscopy (TM-AFM) to analyze unstretched and stretched glowworm (Arachnocampa tasmaniensis) capture threads and revealed nano-scale features corresponding to variation in surface structure and elastic modulus near the surface of the silk. Phase images demonstrated a high resolution of viscoelastic variation and revealed mostly globular and elongated features in the material. Increased vertical orientation of 11–15 nm wide fibrillar features was observed in stretched threads. Fast Fourier transform analysis of phase images confirmed these results. Relative viscoelastic properties were also highly variable at inter- and intra-individual levels. Results of this study demonstrate the practical usefulness of TM-AFM, especially phase angle imaging, in investigating the nano-scale structures that give rise to macro-scale function of soft and highly heterogeneous materials of both natural and synthetic origins.


2007 ◽  
Vol 1049 ◽  
Author(s):  
Dylan J. Morris

AbstractWhile elastic and plastic material property extraction from instrumented indentation tests has been well-studied, similarly-based fracture property measurement remains difficult. Furthermore, estimation of the fracture toughness requires measurement of the crack lengths from a micrograph, which makes nano-scale indentation toughness measurement expensive and difficult. Initiation and propagation of cracks on the nano-scale requires a more acute indenter than a Berkovich or sphere, such as the cube-corner pyramid. Experiments described here were performed on a range of elastic, plastic and brittle materials with diamond indenters of acuity varying between the Berkovich and the cube-corner. These experiments reveal some of what is changed and what remains the same, when the acuity of the probe is changed, when fracture is initiated at the contact, or both. A preliminary model for the physical origin of the extra crack-driving power of acute probes is presented in light of these, and complementary macro-scale in-situ indentation experiments. This work provides the basis for development of instrumented indentation-based nano-scale toughness measurement.


2014 ◽  
Vol 470 ◽  
pp. 205-218 ◽  
Author(s):  
Y. Jin ◽  
N. Hengl ◽  
S. Baup ◽  
F. Pignon ◽  
N. Gondrexon ◽  
...  
Keyword(s):  

2003 ◽  
Vol 125 (4) ◽  
pp. 700-708 ◽  
Author(s):  
George G. Adams ◽  
Sinan Mu¨ftu¨ ◽  
Nazif Mohd Azhar

As loading forces decrease in applications such as MEMS and NEMS devices, the size of the asperity contacts which comprise the real contact area tend to decrease into the nano scale regime. This reduction in size of the contacts is only partially offset by the nominally increased smoothness of these contacting surfaces. Because the friction force depends on the real area of contact, it is important to understand how the material and topographical properties of surfaces contribute to friction forces at this nano scale. In this investigation, the single asperity nano contact model of Hurtado and Kim is incorporated into a multi-asperity model for contact and friction which includes the effect of asperity adhesion forces using the Maugis-Dugdale model. The model spans the range from nano-scale to micro-scale to macro-scale contacts. Three key dimensionless parameters have been identified which represent combinations of surface roughness measures, Burgers vector length, surface energy, and elastic properties. Results are given for the friction coefficient versus normal force, the normal and friction forces versus separation, and the pull-off force for various values of these key parameters.


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