Sulfur in wheat gluten: In situ analysis by X-ray absorption near edge structure (XANES) spectroscopy

The sulfur containing gluten proteins largely determine the baking quality of wheat. In order to probe the speciation of sulfur, gluten proteins [gliadin, high molecular weight (HMW) and low molecular weight (LMW) subunits of glutenin], stored glutenin subunits as well as flour were investigated in situ by S K-edge X-ray near edge absorption structure (XANES) spectroscopy. The spectra confirmed the existence of disulfide bonds in oxidised (oxygen stream) glutenin subunits, supporting their significance for the formation of gluten networks. Additionally, glutenin subunits, which were stored under ambient air and temperature conditions, predominantly contained sulfur of higher oxidation states (sulfoxide, sulfonic acid). The disulfide state and also sulfoxide and sulfonic acid states were detected after reoxidation of glutenin subunits with potassium bromate.     

Synthesis of Novel Niobium Aluminide-Based Composites

A reactive sintering process has been used to produce almost fully dense composites with interpenetrating networks of NbAl₃ and Al₂O₃. The process involves the reaction synthesis of niobium aluminides and Al₂O₃ from compacts of intensively milled aluminum and Nb₂O₅ powder mixtures. During carefully controlled heating under an inert atmosphere, the oxide reduction by aluminum to form niobium aluminides and Al₂O₃ proceeds at temperatures below the melting point of aluminum. At temperatures of >1000°C, the reaction-formed niobium aluminides and Al₂O₃ sinter. The present paper discusses processing parameters, such as attrition milling, the heating cycle, and the metal:ceramic ratio in the starting mixture, that control microstructure development and mechanical properties.     

Peptide Bioconjugates of Electron‐Poor Metallocenes: Synthesis,Characterization, and Anti‐Proliferative Activity

We report the synthesis of metallocene compounds Cp₂M with two different electron‐withdrawing substituents on both cyclopentadienyl rings (hexafluoroacetone (HFA) and chlorobenzoyl ( 1 – 5 ); HFA and COOH ( 6 and 7 ), M=Fe or Ru). The COOH‐containing derivatives were used to synthesize peptide bioconjugates with enkephalin ( 8 and 9 ) and neurotensin ( 10 and 11 ) as well as fluorescein‐labeled neurotensin ( 12 ). All the molecules were fully characterized, including X‐ray structures for 6 and 7 . The physicochemical properties (lipophilicity and electrochemistry) and cytotoxicity on MCF‐7, HT‐29, and PT‐45 cancer cells were evaluated for selected compounds. Electrochemical investigation by cyclic voltammetry revealed that all bis‐substituted metallocenes are up to 300 mV harder to oxidize compared to the monosubstituted 2‐ferrocenylhexafluoropropan‐2‐ol (FcHFA: Δ${E{{{\rm f}\hfill \atop 0\hfill}}}$ =214 mV; disubstituted derivatives: up to Δ${E{{{\rm f}\hfill \atop 0\hfill}}}$ =512 mV; both vs. FcH^0/+). For the bis‐substituted compounds, log P determinations by RP‐HPLC showed increased lipophilicity in comparison to the monosubstituted FcHFA and RcHFA. Cellular uptake was investigated by fluorescence microcopy, and this revealed endosomal entrapment for 12 .     

Mechanisms and Kinetics of Reaction-Bonded Aluminum Oxide Ceramics

Reaction-bonded Al₂O₃ (RBAO) ceramics were fabricated starting from mechanically alloyed Al₂O₃/Al, Al₂O₃/ Al/ZrO₂, and Al₂O₃/Al/ZrO₂/Zr mixtures. Isopressed compacts were heat-treated in air up to 1550°C. Reaction-bonding mechanisms, kinetics, and the influence of ZrO₂ and Zr additions are investigated. Independent of additive, oxidation of Al proceeds both as solid/gas and liquid/gas reaction, and the reaction kinetics follow a parabolic rate law. The reaction rate depends strongly on the particle size of Al. The activation energy of the reaction depends essentially on green density. Below the melting temperature of Al, in samples containing 45 vol% Al and 55 vol% Al₂O₃, it is 112 and 152 kJ/mol at ∼64% and ∼74% TD, respectively, while above the melting temperature, it lies in the range ∼ 26–33 kJ/mol. Zr additions reduce the activation energy to some extent. Samples with only ZrO₂ additions exhibit nearly the same activation energies as ZrO₂-free samples, though ZrO₂ has a very positive effect on the microstructural development in RBAO ceramics. Microstructure evolution and some strength data of RBAO bodies are also reported.     

Bivalent EGFR-Targeting DARPin-MMAE Conjugates

Epidermal growth factor receptor (EGFR) is a validated tumor marker overexpressed in various cancers such as squamous cell carcinoma (SSC) of the head and neck and gliomas. We constructed protein-drug conjugates based on the anti-EGFR Designed Ankyrin Repeat Protein (DARPin) E01, and compared the bivalent DARPin dimer (DD1) and a DARPin-Fc (DFc) to the monomeric DARPin (DM) and the antibody derived scFv425-Fc (scFvFc) in cell culture and a mouse model. The modular conjugation system, which was successfully applied for the preparation of protein-drug and -dye conjugates, uses bio-orthogonal protein-aldehyde generation by the formylglycine-generating enzyme (FGE). The generated carbonyl moiety is addressed by a bifunctional linker with a pyrazolone for a tandem Knoevenagel reaction and an azide for strain-promoted azide-alkyne cycloaddition (SPAAC). The latter reaction with a PEGylated linker containing a dibenzocyclooctyne (DBCO) for SPAAC and monomethyl auristatin E (MMAE) as the toxin provided the stable conjugates DD1-MMAE (drug-antibody ratio, DAR = 2.0) and DFc-MMAE (DAR = 4.0) with sub-nanomolar cytotoxicity against the human squamous carcinoma derived A431 cells. In vivo imaging of Alexa Fluor 647-dye conjugates in A431-xenografted mice bearing subcutaneous tumors as the SCC model revealed unspecific binding of bivalent DARPins to the ubiquitously expressed EGFR. Tumor-targeting was verified 6 h post-injection solely for DD1 and scFvFc. The total of four administrations of 6.5 mg/kg DD1-MMAE or DFc-MMAE twice weekly did not cause any sequela in mice. MMAE conjugates showed no significant anti-tumor efficacy in vivo, but a trend towards increased necrotic areas (p = 0.2213) was observed for the DD1-MMAE (n = 5).     

Trace-based mobility modeling for multi-hop wireless networks

Realistic and scenario-dependent mobility modeling is crucial for the reliable performance evaluation of multi-hop networks. In the last decade, a significant number of synthetic mobility models have been proposed. However, only a few of these models have been validated by realistic movement traces. In the last few years, several of such traces have been collected, analyzed, and made available to the community. This paper provides a comprehensive and up-to-date survey of (1) available movement traces, (2) modeling/analyses of these traces, and (3) synthetic mobility models. The focus of the paper is on mobility traces/models that include position information. The contribution of this paper is to summarize the research that has been done in the area of mobility modeling over the last few years and present challenges for future work.     

Synthesis and Biological Evaluation of Chromium Bioorganometallics Based on the Antibiotic Platensimycin Lead Structure

The recent discovery of the natural product platensimycin as a new antibiotic lead structure has triggered the synthesis of numerous organic derivatives for structure–activity relationship studies. Herein, we describe the synthesis, characterization and biological evaluation of the first organometallic antibiotic inspired by platensimycin. Two bioorganometallic compounds containing (η⁶‐pentamethylbenzene)Cr(CO)₃ ( 2 ) and (η⁶‐benzene)Cr(CO)₃ ( 3 ), linked by an amide bond to the aromatic part of platensimycin, were synthesized. Their antibiotic activities were tested against B. subtilis 168 (Gram positive) and E. coli W3110 (Gram negative) bacterial strains. Both compounds were found to be inactive against E. coli but derivative 2 inhibits B. subtilis growth at a moderate MIC value of 0.15 mM . To test the intrinsic toxicity of chromium, several chromium salts along with {η⁶‐(3‐pentamethylphenyl propionic acid)}Cr(CO)₃ ( 5 ) and {η⁶‐(3‐phenyl propionic acid)}Cr(CO)₃ ( 6 ) were tested against both bacterial strains. No activity was observed against E. coli for any of the compounds; B. subtilis growth was not inhibited by Cr(NO₃)₃ and only very weakly by 5 , K₂Cr₂O₇ and Na₂CrO₄ at MIC values of 0.5, 0.68 and 1.24 mM , respectively. Compounds 2 , 3 , 5 and 4 (the pure organic analogue of 2 ) show similar cytotoxicity against HeLa, HepG2 and HT‐29 mammalian cell lines. Furthermore, the cellular uptake and the intracellular distribution of compounds 2 , 3 and Cr(NO₃)₃ in B. subtilis were studied using atomic absorption spectroscopy to gain insight in to the possible cellular targets. Compound 2 was found to be readily taken up and distributed almost equally among cytosol, cell debris and cell membrane in B. subtilis.     

The ABCs of Space-time-coherence Recording in Holography

Abstract

After placing prior work on time-gated holography and coherence-gated holography in a unified perspective, we broaden both with a new coherence theorem which introduces an assymetry between them and allows otherwise-impossible holograms to be formed.