On Pointed Hopf Algebras of Dimension 2n

We give a structure theorem for pointed Hopf algebras of dimension2ⁿ, having coradical kC₂, where k is an algebraically closedfield of characteristic zero. 1991 Mathematics Subject Classification16W30.     

Stimuli‐Responsive Multilayered Hybrid Nanoparticle/Polyelectrolyte Capsules

Gold nanoparticles (Au_NP) with carboxyl groups on their surface were used in combination with PAH for the layer‐by‐layer coating of CaCO₃ microparticles, followed by the dissolution of the CaCO₃ core. SEM, TEM, and confocal microscopy are used to characterize the hybrid nanoparticles/polyelectrolyte capsules. As the Au_NP have carboxyl groups on their surface, their charge density is pH dependent; therefore, the capsules exhibit a pH‐dependent swelling and can be deconstructed both at low and high pH. By covalent cross‐linking of the carboxyl groups of the Au_NP and the amino groups of the PAH, it is possible to suppress the pH‐responsive behavior. Au_NP are used as activation centers using IR light and this ability is used to release encapsulated material from the nanoparticles/polyelectrolyte capsules as well as for the enhancement of detection and imaging of such capsules by Raman microspectrosopy.

     

Mitigating Plasmonic Absorption Losses at Rear Electrodes in High‐Efficiency Silicon Solar Cells Using Dopant‐Free Contact Stacks

Although charge‐carrier selectivity in conventional crystalline silicon (c‐Si) solar cells is usually realized by doping Si, the presence of dopants imposes inherent performance limitations due to parasitic absorption and carrier recombination. The development of alternative carrier‐selective contacts, using non‐Si electron and hole transport layers, has the potential to overcome such drawbacks and simultaneously reduce the cost and/or simplify the fabrication process of c‐Si solar cells. Nevertheless, devices relying on such non‐Si contacts with power conversion efficiencies (PCEs) that rival their classical counterparts are yet to be demonstrated. In this study, one key element is brought forward toward this demonstration by incorporating low‐pressure chemical vapor deposited ZnO as the electron transport layer in c‐Si solar cells. Placed at the rear of the device, it is found that rather thick (75 nm) ZnO film capped with LiF_x/Al simultaneously enables efficient electron selectivity and suppression of parasitic infrared absorption. Next, these electron‐selective contacts are integrated in c‐Si solar cells with MoO_x‐based hole‐collecting contacts at the device front to realize full‐area dopant‐free‐contact solar cells. In the proof‐of‐concept device, a PCE as high as 21.4% is demonstrated, which is a record for this novel device class and is at the level of conventional industrial solar cells.     

Magnetic Electrospun Fibers for Cancer Therapy

Iron oxide nanoparticles (IONPs) for magnetic hyperthermia in cancer treatment have recently gained substantial interest. Unfortunately, the use of free IONPs still faces major challenges such as poor tumor targetability, high variability in the amount of IONPs taken up by the tumor and the IONP leakage from dead cancer cells into the surrounding healthy tissues. The present work reports on electrospun fiber webs, heavily loaded with 50 nm sized IONPs. The high loading capacity of the fibers enables significant heating of the environment upon applying an alternating magnetic field. Furthermore, magnetic fibers can be repeatedly heated without loss of heating capacity or release of IONPs. Upon functionalization of the fiber surface with collagen, human SKOV‐3 ovarian cancer cells attached well to the fibers. Applying an alternating magnetic field during 10 minutes to the fiber webs killed all fiber‐associated cancer cells. Killing the cells using this method seemed more efficient compared to the use of a warm water bath. As the fiber webs can be i) loaded with a well‐controlled amount of IONPs and ii) localized in the body by Magnetic Resonance Imaging, magnetic electrospun fibers may become promising materials for a highly reproducible (repeated) heating of cancer tissues in vivo.     

Delivering scalable video with QoS to the home

User satisfaction is a key factor in the success of novel multimedia services. Yet, to enable service providers and network operators to control and maximize the quality (QoS, QoE) of delivered video streams, quite some challenges remain. In this paper, we particularly focus on three of them. First of all, objectively measuring video quality requires appropriate quality metrics and methods of assessing them in a real-time fashion. Secondly, the recent Scalable Video Coding (SVC) format opens opportunities for adapting video to the available (network) resources, yet the appropriate configuration of video encoding as well as real-time streaming adaptation are largely unaddressed research areas. Thirdly, while bandwidth reservation mechanisms in access/core networks do exist, service providers lack a means for guaranteeing QoS in the increasingly complex home networks (which they are not in full control of). In this paper we offer a broad view on these interrelated issues, by presenting the developments originating in a Flemish research project (including proof-of-concept demonstrations). From a developmental perspective, we propose an architecture combining a real-time video quality monitoring platform, on-the-fly adaptation (optimizing the video quality) and QoS reservation in a heterogeneous home network based on UPnP QoS?v3. From a research perspective, we propose a new subjective test procedure that revealed user preference for temporal scalability over quality scalability. In addition, an extensive study on optimizing HD SVC encoding in IPTV scenarios with fluctuating bandwidth showed that under certain bandwidth constraints (prohibiting sufficient fidelity) spatial scalability is a better option than quality scalability.     

Faraday rotation and its dispersion in the visible region for saturated organic liquids

Faraday rotation and its dispersion have been measured and calculated in the 400-800 nm wavelength range for a set of saturated organic liquids. The resulting Verdet constants are fitted and trends are analyzed. Comparisons are made to both the polarizability and diamagnetic susceptibility. The data are applied to a connectivity index model, allowing prediction of Verdet constants of aliphatic organic liquids from 400 to 800 nm. The observed correlations and connectivity model improve the understanding of Faraday rotation in diamagnetic materials, allowing for future optimization.     

An inner amenable group whose von Neumann algebra does not have property Gamma

We construct inner amenable groups G with infinite conjugacy classes and such that the associated II₁ factor has no non-trivial asymptotically central elements, i.e. does not have property Gamma of Murray and von Neumann. This solves a problem posed by Effros in 1975.     

Designing polymeric particles for antigen delivery

By targeting dendritic cells, polymeric carriers in the nano to lower micron range constitute very interesting tools for antigen delivery. In this critical review, we review how new immunological insights can be exploited to design new carriers allowing one to tune immune responses and to further increase vaccine potency (137 references).     

Extensions of locally compact quantum groups and the bicrossed product construction

In the framework of locally compact quantum groups, we study cocycle actions. We develop the cocycle bicrossed product construction, starting from a matched pair of locally compact quantum groups. We define exact sequences and establish a one-to-one correspondence between cocycle bicrossed products and cleft extensions. In this way, we obtain new examples of locally compact quantum groups.