Poly(Sarcosine) Surface Modification Imparts Stealth‐Like Properties to Liposomes

Circulation lifetime is a crucial parameter for a successful therapy with nanoparticles. Reduction and alteration of opsonization profiles by surface modification of nanoparticles is the main strategy to achieve this objective. In clinical settings, PEGylation is the most relevant strategy to enhance blood circulation, yet it has drawbacks, including hypersensitivity reactions in some patients treated with PEGylated nanoparticles, which fuel the search for alternative strategies. In this work, lipopolysarcosine derivatives (BA‐pSar, bisalkyl polysarcosine) with precise chain lengths and low polydispersity indices are synthesized, characterized, and incorporated into the bilayer of preformed liposomes via a post insertion technique. Successful incorporation of BA‐pSar can be realized in a clinically relevant liposomal formulation. Furthermore, BA‐pSar provides excellent surface charge shielding potential for charged liposomes and renders their surface neutral. Pharmacokinetic investigations in a zebrafish model show enhanced circulation properties and reduction in macrophage recognition, matching the behavior of PEGylated liposomes. Moreover, complement activation, which is a key factor in hypersensitivity reactions caused by PEGylated liposomes, can be reduced by modifying the surface of liposomes with an acetylated BA‐pSar derivative. Hence, this study presents an alternative surface modification strategy with similar benefits as the established PEGylation of nanoparticles, but with the potential of reducing its drawbacks.     

Limit load and failure mechanisms of soda lime glass foam

Foamed glass is widely used in the industry as an insulating material. However, its mechanical properties are not well-investigated yet. Foamed glass is produced from glass waste that causes discrepancy in mechanical properties of the final product. This paper shows a way to increase the limit of the load capacity of foamed glass, which is very fragile and sensitive to mechanical and thermal loading conditions. In this paper, three different methods of load application on cellular glass structure (rough contact, resin and flour interfaces) and their influence on failure mechanisms were investigated in detail. The results of numerical analyses, based on finite elements method and compression strength tests using the digital image correlation method, indicate that the overall strength of the material is limited by boundary effects. A careful adjustment of the interface property is the main factor to draw useful conclusions and to extend load limits of cellular glass in engineering applications.     

Combined cerium oxide nanocapping and layer-by-layer coating of porous silicon containers for controlled drug release

Local drug release in close vicinity of solid tumors is a promising therapeutic approach in cancer therapy. Implantable drug delivery systems can be designed to achieve controlled and sustained drug release. In this study, ultrathin porous membranes of silicon wafer were employed as compatible drug reservoir models. An anticancer model drug, curcumin (CUR), was successfully loaded into porous silicon containers (8.94?±?0.72% w/w), and then, cerium oxide nanocapping was performed on the open pores for drug protection and release rate prolongation. Next, layer-by-layer surface coating of the drug container with anionic (alginate) and cationic (chitosan) polymers rendered pH-responsivity to the device. The drug release profile was studied using reflectometric interference Fourier transform spectroscopy at different pH conditions. It was determined that faster decomposition of the polymeric layers and subsequent CUR release occur in acidic buffer (pH 5.5) compared to a neutral buffer. Various characterization studies, including dynamic light scattering, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy, contact angle measurement, ultraviolet–visible spectroscopy, and X-ray powder diffraction revealed that our system has the required physicochemical properties to serve as a novel pH-sensitive drug delivery implant for cancer therapy.     

Stimulated Transitions of Directed Nonequilibrium Self‐Assemblies

Near‐equilibrium stimulus‐responsive polymers have been used extensively to introduce morphological variations in dependence of adaptable conditions. Far‐less‐well studied are triggered transformations at constant conditions. These require the involvement of metastable states, which are either able to approach the equilibrium state after deviation from metastability or can be frozen on returning from nonequilibrium to equilibrium. Such functional nonequilibrium macromolecular systems hold great promise for on‐demand transformations, which result in substantial changes in their material properties, as seen for triggered gelations. Herein, a diblock copolymer system consisting of a hydrophilic block and a block that is responsive to both pressure and temperature, is introduced. This species demonstrates various micellar transformations upon leaving equilibrium/nonequilibrium states, which are triggered by a temperature deflection or a temporary application of hydrostatic pressure.     

What Happens during Thermal Post-Treatment of Powder Aerosol Deposited Functional Ceramic Films? Explanations Based on an Experiment-Enhanced Literature Survey

Powder aerosol deposition (PAD) is a unique ceramic spray coating method that produces dense and well-adhering thick-films directly at room temperature, without requiring any heating or sintering. After the successful film formation, mechanical film properties like hardness or plasma resistance are remarkably good. However, when it comes to electrical properties like permittivity or electrical conductivity, the nanocrystalline structure of PAD films combined with high internal strains deteriorates partly the characteristic properties. The electrical conductivity may already be present within the as-deposited films. However, it is mostly lowered by several orders of magnitude. Therefore, a thermal post-deposition annealing is oftentimes required. In this work, electrically conducting films produced by powder aerosol deposition are surveyed based on published data. Their microstructural and electrical behavior during the post-deposition annealing treatment is summarized and reasons for the lowered electrical conductivity are identified. Additionally, the processes taking place during annealing, which eventually allow to regain bulk-like functional properties, are examined. A universal annealing behavior is found that leads to a quantitative recommendation for the suitable film annealing temperatures to regain the electrical conductivities.     

Balancing the Fluency-Consistency Tradeoff in Collaborative Information Search with a Recommender Approach

Creative group work can be supported by collaborative search and annotation of Web resources. In this setting, it is important to help individuals both stay fluent in generating ideas of what to search next (i.e., maintain ideational fluency) and stay consistent in annotating resources (i.e., maintain organization). Based on a model of human memory, we hypothesize that sharing search results with other users, such as through bookmarks and social tags, prompts search processes in memory, which increase ideational fluency, but decrease the consistency of annotations, e.g., the reuse of tags for topically similar resources. To balance this tradeoff, we suggest the tag recommender SoMe, which is designed to simulate search of memory from user-specific tag-topic associations. An experimental field study (N = 18) in a workplace context finds evidence of the expected tradeoff and an advantage of SoMe over a conventional recommender in the collaborative setting. We conclude that sharing search results supports group creativity by increasing the ideational fluency, and that SoMe helps balancing the evidenced fluency-consistency tradeoff.     

<Emphasis Type="Italic">μ</Emphasis>DTNSec: a security layer with lightweight certificates for Disruption-Tolerant Networks on microcontrollers

In Delay/Disruption-Tolerant Networks, man-in-the-middle attacks are easy: due to the store-carry-forward principle, an attacker can simply place itself on the route between source and destination to eavesdrop or alter bundles. This weakness is aggravated in networks, where devices are energy-constrained but the attacker is not. To protect against these attacks, we design and implement μDTNSec, a security layer for Delay/Disruption-Tolerant Networks on microcontrollers. Our design establishes a public key infrastructure with lightweight certificates as an extension to the Bundle Protocol. It has been fully implemented as an addition to μDTN on Contiki OS and uses elliptic curve cryptography and hardware-backed symmetric encryption. In this enhanced version of μDTNSec, public key identity bindings are validated by exchanging certificates using neighbor discovery. μDTNSec provides a signature mode for authenticity and a sign-then-encrypt mode for added confidentiality. Our performance evaluation shows that the choice of the curve dominates the influence of the payload size. We also provide energy measurements for all operations to show the feasibility of our security layer on energy-constrained devices. Because a high quality source of randomness is required, we evaluated the random number generators by the AT86RF231 radio, its successor AT86RF233, and one based on the noise of the A/D converter. We found that only AT86RF233 provides the required quality.     

Thermal Decomposition of Partially Hydrogenated Rapeseed Oil During Repeated Frying Traditional and Fast French Fries

The aim of this study was to compare thermal degradation of oil, especially the composition of the polymer in a polar and nonpolar fraction of oil, used for repeated frying of fast and traditional French fries. The French fries were fried using the partially hydrogenated rapeseed oil. Fast French fries were characterized by a half shorter frying time compared to traditional ones. The frying process was done at 170 °C ± 5 °C in 5‐l electric fryers and carried out in 15‐min cycles for 48 hours. The content of thermal decomposition of triacylglycerol (TAG) in both fractions of oil was analyzed by high‐performance size‐exclusion chromatography (HPSEC). In all analyzed samples, thermal decomposition products were found. However, the composition of a polar and nonpolar fraction of oil was not the same. In a nonpolar fraction, only the monomers and hydrolysis products of TAG were observed. In a polar fraction, dimers, trimers, and oligomers of TAG were also found. The shorter time of frying the fast French fries resulted in a lower total and individual polymers content in all steps of analysis compared to the oil used for frying the traditional French fries.     

A high frequency sensor for optical beam deflection atomic force microscopy

We demonstrate a novel electronic readout for quadrant photodiode based optical beam deflection setups. In our readout, the signals used to calculate the deflections remain as currents, instead of undergoing an immediate conversion to voltages. Bipolar current mirrors are used to perform all mathematical operations at the transistor level, including the signal normalizing division. This method has numerous advantages, leading to significantly simpler designs that avoid large voltage swings and parasitic capacitances. The bandwidth of our readout is solely limited by the capacitance of the quadrant photodiode junctions, making the effective bandwidth a function of the intensity of photocurrents and thus the applied power of the beam deflection laser. Using commercially available components and laser intensities of 1-4 mW we achieved a 3 dB bandwidth of 20 MHz with deflection sensitivities of up to 0.5-1 V/nm and deflection noise levels below 4.5 fm/Hz. Atomic resolution imaging of muscovite mica using FM-AFM in water demonstrates the sensitivity of this novel readout.