Hierarchical cross-linking in physical alginate gels: a rheological and dynamic light scattering investigation

We investigate the dynamics of alginate gels, an important class of biopolymer-based viscoelastic materials, by combining mechanical tests and non-conventional, time-resolved light scattering methods. Two relaxation modes are observed upon applying a compressive or shear stress. Dynamic light scattering and diffusive wave spectroscopy measurements reveal that these modes are associated with discontinuous rearrangement events that restructure the gel network via anomalous, non-diffusive microscopic dynamics. We show that these dynamics are due to both thermal activation and internal stress stored during gelation and propose a scenario where a hierarchy of cross-links with different life times is responsible for the observed complex behavior. Measurements at various temperatures and sample ages are presented to support this scenario.Comment: To appear in Soft Matte

Concentrated suspensions of Brownian beads in water: dynamic heterogeneities trough a simple experimental technique

Concentrated suspensions of Brownian hard-spheres in water are an epitome for understanding the glassy dynamics of both soft materials and supercooled molecular liquids. From an experimental point of view, such systems are especially suited to perform particle tracking easily, and, therefore, are a benchmark for novel optical techniques, applicable when primary particles cannot be resolved. Differential Variance Analysis (DVA) is one such novel technique that simplifies significantly the characterization of structural relaxation processes of soft glassy materials, since it is directly applicable to digital image sequences of the sample. DVA succeeds in monitoring not only the average dynamics, but also its spatio-temporal fluctuations, known as dynamic heterogeneities. In this work, we study the dynamics of dense suspensions of Brownian beads in water, imaged through digital video-microscopy, by using both DVA and single-particle tracking. We focus on two commonly used signatures of dynamic heterogeneities: the dynamic susceptibility, $\chi_4$, and the non-Gaussian parameter, $\alpha_2$. By direct comparison of these two quantities, we are able to highlight similarities and differences. We do confirm that $\chi_4$ and $\alpha_2$ provide qualitatively similar information, but we find quantitative discrepancies in the scalings of characteristic time and length scale on approaching the glass transition.Comment: The original publication is available at http://www.scichina.com and http://www.springerlink.com http://engine.scichina.com/publisher/scp/journal/SCPMA/doi/10.1007/s11433-019-9401-x?slug=abstrac

Limited Liability Companies and Estate Planning

Discusses court cases involving the use of limited liability companies as an estate planning tool in the U.S. Facts of the case of Estate of Strangi versus Commissioner; Stance of the court on the transfers made to the limited partnership; Impact of the case of Kimbell versus U.S. on the use of limited liability companies as estate planning vehicles

Friday timing plus social media multipliers may mean Paris attacks have more impacts on markets

The true consequence to business remains to be seen, write Michael D. Larobina and Richard L. Pat

The Impact of Terrorism on Business

Terrorism has in one form or another been a part of society throughout history. Since the September 11, 2001 attacks in New York, the world community has been more focused on terrorism than ever before in most recent modern history. Terrorism has impacted multiple levels of society across the world community. One of those levels is the business environment. A specific aim of terrorism is to disrupt and destroy ongoing businesses. Therefore, the ability of governments to disrupt and destroy terrorism is essential to the continued growth and expansion of the world economy. Terrorism will directly impact a country\u27s ability to attract and maintain business development and investment. This paper examines the impact of terrorism on five business sectors: the equities market, aviation, tourism, insurance and corporate security. An examination of the available literature and data concludes there is an initial detrimental impact on all these business sectors. However, available data trends in the direction of no long-term disruption. The economic costs, however, are present and most business sectors endure additional economic costs as a result of terrorism

Elastic and dynamic heterogeneity in aging alginate gels

Anomalous aging in soft glassy materials has generated a great deal of interest because of some intriguing features of the underlying relaxation process, including the emergence of “ultra-long-range” dynamical correlations. An intriguing possibility is that such a huge correlation length is reflected in detectable ensemble fluctuations of the macroscopic material properties. We tackle this issue by performing replicated mechanical and dynamic light scattering (DLS) experiments on alginate gels, which recently emerged as a good model-system of anomalous aging. Here we show that some of the monitored quantities display wide variability, including large fluctuations in the stress relaxation and the occasional presence of two-step decay in the DLS decorrelation functions. By quantifying elastic fluctuation through the standard deviation of the elastic modulus and dynamic heterogeneities through the dynamic susceptibility, we find that both quantities do increase with the gel age over a comparable range. Our results suggest that large elastic fluctuations are closely related to ultra-long-range dynamical correlation, and therefore may be a general feature of anomalous aging in gels

The Status Of Recognition And Enforcement Of Judgments In The European Union

International trade and the free movement of people are inevitably followed by legal disputes. Such litigants require an efficient and predictable dispute resolution mechanism capable of handling cases between diverse nationals. An essential part of such mechanism is a clearly defined process of judgment enforcement across national boundaries. In the past several decades, the European Union (“EU”) has necessarily addressed judgment enforcement across the boundaries of its member nations (“Member States”). Citizens of the EU need to prosecute and defend their legal rights in their home and in other EU member states. Presently, the EU is, again, considering such issues and is poised to make some changes in this area. As with past EU legislation regarding judgment recognition and enforcement, the proposed changes are intended to promote the growth of the European economy by encouraging and furthering cross-border trade and the free movement of people. This paper presents the following, (1) a brief introduction to civil and commercial judgment recognition and enforcement in the EU, (2) the current status of judgment enforcement as exemplified in significant case law, (3) the deficiencies of current EU judgment enforcement Brussels Is, and finally, (3) the proposed changes to such Brussels I currently

Investigation on the thermal gelation of Chitosan/\u3b2-Glycerophosphate solutions

This work deals with the effect of temperature on the thermal-gelation process of water solutions containing chitosan \u3b2-glycerolphosphate disodium salt hydrate. In particular, the attention is focused on the role played by temperature on the gel final properties, a very important aspect in the frame of drug delivery systems. The study was performed by combining rheology and low field nuclear magnetic resonance, two approaches that revealed to be highly synergic as they can detect different aspects of the developing polymeric network. This study indicates that 30 \ub0C represent a sort of threshold for both the gelation kinetics and the gel final properties. Indeed, above this temperature, gelation kinetics was rapid and yielded to a strong gel. On the contrary, a slow kinetics and a final weak gel occurred below 30 \ub0C. Finally, rheology and low field NMR allowed, independently, evaluating the time evolution of the network mesh size upon gelation

Finite Element Analysis Investigate Pulmonary Autograft Root and Leaflet Stresses to Understand Late Durability of Ross Operation

Ross operation might be a valid option for congenital and acquired left ventricular outflow tract disease in selected cases. As the pulmonary autograft is a living substitute for the aortic root that bioinspired the Ross operation, we have created an experimental animal model in which the vital capacity of the pulmonary autograft (PA) has been studied during physiological growth. The present study aims to determine any increased stresses in PA root and leaflet compared to the similar components of the native aorta. An animal model and a mathematical analysis using finite element analysis have been used for the purpose of this manuscript. The results of this study advance our understanding of the relative benefits of pulmonary autograft for the management of severe aortic valve disease. However, it launches a warning about the importance of the choice of the length of the conduits as mechanical deformation, and, therefore, potential failure, increases with the length of the segment subjected to stress. Understanding PA root and leaflet stresses is the first step toward understanding PA durability and the regions prone to dilatation, ultimately to refine the best implant technique

Frequency encoding for simultaneous display of multimodality images.

An original method for simultaneous display of functional and anatomic images, based on frequency encoding (FE), merges color PET with T1-weighted MR brain images, and grayscale PET with multispectral color MR images. A comparison with two other methods reported in the literature for image fusion (averaging and intensity modulation techniques) was performed. Methods: For FE, the Fourier transform of the merged image was obtained summing the low frequencies of the PET image and the high frequencies of the MR image. For image averaging, the merged image was obtained as a weighted average of the intensities of the two images to be merged. For intensity modulation, the red, green and blue components of the color image were multiplied on a pixel- by-pixel basis by the grayscale image. A comparison of the performances of the three techniques was made by three independent observers assessing the conspicuity of specific MRI and PET information in the merged images. For evaluation purposes, images from seven patients and a computer-simulated MRI/PET phantom were used. Data were compared with a chi-square test applied to ranks. Results: For the depiction of MRI and PET information when merging color PET and T1-weighted MR images, FE was rated superior to intensity modulation and averaging techniques in a significant number of comparisons. For merging grayscale PET with multispectral color MR images, FE and intensity modulation were rated superior to image averaging in terms of both MRI and PET information. Conclusion: The data suggest that improved simultaneous evaluation of MRI and PET information can be achieved with a method based on FE