Self-Assembling Hydrogels Based on a Complementary Host-Guest Peptide Amphiphile Pair

Supramolecular polymer-based biomaterials play a significant role in current biomedical research. In particular, peptide amphiphiles (PAs) represent a promising material platform for biomedical applications given their modular assembly, tunability, and capacity to render materials with structural and molecular precision. However, the possibility to provide dynamic cues within PA-based materials would increase the capacity to modulate their mechanical and physical properties and, consequently, enhance their functionality and broader use. In this study, we report on the synthesis of a cationic PA pair bearing complementary adamantane and β-cyclodextrin host–guest cues and their capacity to be further incorporated into self-assembled nanostructures. We demonstrate the possibility of these recognition motifs to selectively bind, enabling noncovalent cross-linking between PA nanofibers and endowing the resulting supramolecular hydrogels with enhanced mechanical properties, including stiffness and resistance to degradation, while retaining in vitro biocompatibility. The incorporation of the host–guest PA pairs in the resulting hydrogels allowed not only for macroscopic mechanical control from the molecular scale, but also for the possibility to engineer further spatiotemporal dynamic properties, opening opportunities for broader potential applications of PA-based materials

Green Synthesis of Glycopolymers Using an Enzymatic Approach

beta-Glucosidase and horseradish peroxidase (HRP) are used as biocatalysts in aqueous solution for the enzymatic synthesis of glycomonomers and the respective enzymatic polymerization toward glycopolymers. The biocatalytically synthesized monomers contain (meth)acrylate functionalities that are able to be polymerized by an enzyme-initiated polymerization using an HRP/hydrogen peroxide/acetylacetone ternary system. The structure of the glycomonomers and the respective glycopolymers as well as the monomer conversion after the reaction are determined by H-1 NMR spectroscopy. The synthesized glycopolymers have a dispersity and a number-average molecular weight up to 5.8 and 297 kg mol(-1), respectively. Thermal and degradation properties of the glycopolymers are studied by differential scanning calorimetry and thermogravimetric analysis. In addition, preparation of glycopolymers via conventional free radical polymerization is performed and the properties of the obtained polymers are compared with the enzymatically synthesized glycopolymers

Moment Matching-Based Distribution Fitting with Generalized Hyper-Erlang Distributions

This paper describes a novel moment matching based fitting method for phase-type (PH) distributions. A special sub-class of phase-type distributions is introduced for the fitting, called generalized hyper-Erlang distributions. The user has to provide only two parameters: the number of moments to match, and the upper bound for the sum of the multiplicities of the eigenvalues of the distribution, which is related to the maximal size of the resulting PH distribution. Given these two parameters, our method obtains all PH distributions that match the target moments and have a Markovian representation up to the given size. From this set of PH distributions the best one can be selected according to any distance function

Associations of cardiovascular risk factors in Al Ain- United Arab Emirates

<p>Abstract</p> <p>Background</p> <p>Over the last 30 years the citizens of the United Arab Emirates have experienced major changes in life-style secondary to increased affluence. Currently, 1 in 5 adults have diabetes mellitus, but the associations (clustering) among risk factors, as well as the relevance of the concept of the metabolic syndrome, in this population is unknown.</p> <p>Aim</p> <p>To investigate the prevalence and associations among cardiovascular risk factors in this population, and explore to what extent associations can be explained by the metabolic syndrome according to ATP-III criteria.</p> <p>Method</p> <p>A community based survey, of conventional risk factors for cardiovascular disease was conducted among 817 national residents of Al Ain city, UAE. These factors were fasting blood sugar, blood pressure, lipid profile, BMI, waist circumference, smoking, or CHD family history. Odds ratios between risks factors, both unadjusted and adjusted for age and sex as well as adjusted for age, sex, and metabolic syndrome were calculated.</p> <p>Results</p> <p>Various risk factors were positively associated in this population; associations that are mostly unexplained by confounding by age and sex. For example, hypertension and diabetes were still strongly related (OR 2.5; 95% CI 1.7–3.7) after adjustment. An increased waist circumference showed similar relationship with hypertension (OR 2.3; 95% CI 1.5–3.5). Diabetes was related to an increased BMI (OR 1.5; 96% CI 1.0–2.3). Smoking was also associated with diabetes (OR 1.9, 95% CI 1.0–3.3).</p> <p>Further adjustment for metabolic syndrome reduced some associations but several remained.</p> <p>Conclusion</p> <p>In this population risk-factors cluster, but associations do not appear to be explained by the presence/absence of the ATP-III metabolic syndrome. Associations provide valuable information in planning interventions for screening and management.</p

Static and active tactile perception and touch anisotropy: aging and gender effect

Abstract Although the human finger is the interface used for the touch process, very few studies have used its properties to provide a description of tactile perception regarding age and gender effects. Age and gender effects on the biophysical properties of the human finger were the main topics of our previous study. Correlating tactile perception with each parameter proved very complex. We expand on that work to assess the static and dynamic touch in addition to the touch gestures. We also investigate the age and gender effects on tactile perception by studying the finger size and the real contact area (static and dynamic) of forty human fingers of different ages and gender. The size of the finger and the real contact area (static and dynamic) define the density of the mechanoreceptors. This density is an image of the number of mechanoreceptors solicited and therefore of tactile perception (static and dynamic). In addition, the touch gestures used to perceive an object’s properties differ among people. Therefore, we seek to comprehend the tactile perception of different touch gestures due to the anisotropy of mechanical properties, and we study two different directions (top to bottom and left to right)

Surface waves in a magnetized ferrite slab filled with a wire medium

Novel metamaterial, based on wire medium embedded into magnetized ferrite, is studied. Waves in unbounded ferrites filled with wire media, surface wave at the interface of this metamaterial and the air as well as waves in a ferrite slab adjacent to a wire medium are considered. Different geometries of wires arrangement and different magnetization directions are discussed. Effective permeability was introduced for the case where both plasma and magnetic properties take place. Dispersion diagrams and applicability of the Drude model for the description of the wire medium in a host matrix, possessing high permittivity and permeability, are discussed

Q-factor investigation of antennas over metamaterials substrates

International audienceIn this article, antennas over metamaterials substrates are investigated with the radiating Q factor determined by using a time‐domain method.The main objective is to illustrate the electromagnetic behavior of this kind of complex structure by calculating its energy budget (stored and radiated energies). An example of a patch antenna using such materials is analyzed and experimental results are presented

Picture-perfect Streaming over the Internet: Is There Hope?

Quality of service (QoS) in streaming of continuous media (CM) over the Internet is poor, which is partly due to variations in delays, bandwidth limitations, and packet losses. Although CM applications can tolerate some missing data, non-recoverable information loss degrades these applications&apos; QoS. Consequently, a number of application areas (e.g., those related to the entertainment industry) have backed away from streaming of their content over the Internet