Strategies for Dispersing Nanoparticles in Polymers

MRS Bulletin ◽  
2007 ◽  
Vol 32 (4) ◽  
pp. 341-347 ◽  
Author(s):  
Ramanan Krishnamoorti

AbstractControlling the dispersion of nanoparticles in polymeric matrices is the most significant impediment in the development of high-perform ance polymer nanocomposite ma te rials and results primarily from the strong interpar ticle interactions between the nanopar ticles. This review examines the theoretical and experimental strategies employed in developing appropriate chemical and physical methods to achieve controlled dispersion of nanopar ticles. Methods to characterize the state of dispersion, including force and electron micros copy, and scattering, electrical, and mechanical spectroscopy, are considered with special emphasis on achieving quantitative meas ures of the dispersion. Some of the outstanding issues, such as long-term aging and the implication for the dispersion of nanopar ticles, development of high-throughput methods for rapid screening, and methods for in-line monitoring, are also discussed.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Woo Seok Kim ◽  
Sungcheol Hong ◽  
Milenka Gamero ◽  
Vivekanand Jeevakumar ◽  
Clay M. Smithhart ◽  
...  

AbstractThe vagus nerve supports diverse autonomic functions and behaviors important for health and survival. To understand how specific components of the vagus contribute to behaviors and long-term physiological effects, it is critical to modulate their activity with anatomical specificity in awake, freely behaving conditions using reliable methods. Here, we introduce an organ-specific scalable, multimodal, wireless optoelectronic device for precise and chronic optogenetic manipulations in vivo. When combined with an advanced, coil-antenna system and a multiplexing strategy for powering 8 individual homecages using a single RF transmitter, the proposed wireless telemetry enables low cost, high-throughput, and precise functional mapping of peripheral neural circuits, including long-term behavioral and physiological measurements. Deployment of these technologies reveals an unexpected role for stomach, non-stretch vagal sensory fibers in suppressing appetite and demonstrates the durability of the miniature wireless device inside harsh gastric conditions.


1999 ◽  
Vol 575 ◽  
Author(s):  
H.-P. Brack ◽  
M. M. Koebel ◽  
A. Tsukada ◽  
J. Huslage ◽  
F. Buechi ◽  
...  

ABSTRACTWe have demonstrated earlier the useful performance of our PSI radiation-grafted membranes in terms of the current-voltage characteristics of 30 cm2 active area fuel cells containing these membranes and their long-term testing over 6,000 h at 60 °C. We report here on testing of PSI radiation-grafted membranes in these fuel cells at 80 °C and in short stacks comprised of two or four 100 cm2 active area cells. The in-situ degradation of membranes has been investigated by characterizing membranes both before testing in fuel cells and post-mortem after testing in fuel cells. Characterization was accomplished by means of ion-exchange capacity and infrared and Raman spectroscopic measurements. In addition, a rapid screening method for our ex-situ testing of the oxidative stability of proton-conducting membranes was developed in this work. Comparison of the initial screening test results concerning the oxidative stability of some perfluorinated, partially-fluorinated, and non-fluorinated membranes compare well qualitatively with the relative stability of these same membranes during their long-term testing in fuel cells.


mBio ◽  
2017 ◽  
Vol 8 (6) ◽  
Author(s):  
Yushen Du ◽  
Tian-Hao Zhang ◽  
Lei Dai ◽  
Xiaojuan Zheng ◽  
Aleksandr M. Gorin ◽  
...  

ABSTRACT Certain “protective” major histocompatibility complex class I (MHC-I) alleles, such as B*57 and B*27, are associated with long-term control of HIV-1 in vivo mediated by the CD8+ cytotoxic-T-lymphocyte (CTL) response. However, the mechanism of such superior protection is not fully understood. Here we combined high-throughput fitness profiling of mutations in HIV-1 Gag, in silico prediction of MHC-peptide binding affinity, and analysis of intraperson virus evolution to systematically compare differences with respect to CTL escape mutations between epitopes targeted by protective MHC-I alleles and those targeted by nonprotective MHC-I alleles. We observed that the effects of mutations on both viral replication and MHC-I binding affinity are among the determinants of CTL escape. Mutations in Gag epitopes presented by protective MHC-I alleles are associated with significantly higher fitness cost and lower reductions in binding affinity with respect to MHC-I. A linear regression model accounting for the effect of mutations on both viral replicative capacity and MHC-I binding can explain the protective efficacy of MHC-I alleles. Finally, we found a consistent pattern in the evolution of Gag epitopes in long-term nonprogressors versus progressors. Overall, our results suggest that certain protective MHC-I alleles allow superior control of HIV-1 by targeting epitopes where mutations typically incur high fitness costs and small reductions in MHC-I binding affinity. IMPORTANCE Understanding the mechanism of viral control achieved in long-term nonprogressors with protective HLA alleles provides insights for developing functional cure of HIV infection. Through the characterization of CTL escape mutations in infected persons, previous researchers hypothesized that protective alleles target epitopes where escape mutations significantly reduce viral replicative capacity. However, these studies were usually limited to a few mutations observed in vivo. Here we utilized our recently developed high-throughput fitness profiling method to quantitatively measure the fitness of mutations across the entirety of HIV-1 Gag. The data enabled us to integrate the results with in silico prediction of MHC-peptide binding affinity and analysis of intraperson virus evolution to systematically determine the differences in CTL escape mutations between epitopes targeted by protective HLA alleles and those targeted by nonprotective HLA alleles. We observed that the effects of Gag epitope mutations on HIV replicative fitness and MHC-I binding affinity are among the major determinants of CTL escape. IMPORTANCE Understanding the mechanism of viral control achieved in long-term nonprogressors with protective HLA alleles provides insights for developing functional cure of HIV infection. Through the characterization of CTL escape mutations in infected persons, previous researchers hypothesized that protective alleles target epitopes where escape mutations significantly reduce viral replicative capacity. However, these studies were usually limited to a few mutations observed in vivo. Here we utilized our recently developed high-throughput fitness profiling method to quantitatively measure the fitness of mutations across the entirety of HIV-1 Gag. The data enabled us to integrate the results with in silico prediction of MHC-peptide binding affinity and analysis of intraperson virus evolution to systematically determine the differences in CTL escape mutations between epitopes targeted by protective HLA alleles and those targeted by nonprotective HLA alleles. We observed that the effects of Gag epitope mutations on HIV replicative fitness and MHC-I binding affinity are among the major determinants of CTL escape.


2017 ◽  
Vol 106 (4) ◽  
pp. 1183-1186 ◽  
Author(s):  
Mette D. Mosgaard ◽  
Philip J. Sassene ◽  
Huiling Mu ◽  
Thomas Rades ◽  
Anette Müllertz

Author(s):  
Daniel B. Miracle ◽  
Mu Li ◽  
Zhaohan Zhang ◽  
Rohan Mishra ◽  
Katharine M. Flores

Structural materials have lagged behind other classes in the use of combinatorial and high-throughput (CHT) methods for rapid screening and alloy development. The dual complexities of composition and microstructure are responsible for this, along with the need to produce bulk-like, defect-free materials libraries. This review evaluates recent progress in CHT evaluations for structural materials. High-throughput computations can augment or replace experiments and accelerate data analysis. New synthesis methods, including additive manufacturing, can rapidly produce composition gradients or arrays of discrete alloys-on-demand in bulk form, and new experimental methods have been validated for nearly all essential structural materials properties. The remaining gaps are CHT measurement of bulk tensile strength, ductility, and melting temperature and production of microstructural libraries. A search strategy designed for structural materials gains efficiency by performing two layers of evaluations before addressing microstructure, and this review closes with a future vision of the autonomous, closed-loop CHT exploration of structural materials. Expected final online publication date for the Annual Review of Materials Science, Volume 51 is August 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.


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