Mono-detection spatially super resolved microwave imaging for RADAR applications

In this paper we present a novel RF photonic approach to radar scanning and imaging. The operating principle is based upon a system in which several (in our case two) radiating microwave sources generate and project at far field, a moving grating pattern over an object, e.g. by linearly modifying the relative phase between the microwave sources. Capturing a set of such integrated reflections (we work only with a mono detector) coming from the object at different radio frequencies (due to a simultaneously performed spectral scanning) can spatially reconstruct high resolution image of the object despite the fact that the sensing was performed with a small mono receiving antenna.     

Lysozyme-imprinted polymer synthesized using UV free-radical polymerization

Molecular imprinting is a method to fabricate a polymeric material (molecularly imprinted polymer or MIP) capable of selectively recognizing template molecules. Molecular imprinting of small molecules has been studied widely. Less common, however, is the imprinting of biological macromolecules, including proteins, among which lysozyme is an important molecule in the food, pharmaceutical, and diagnostic sciences. In this study, lysozyme MIP was fabricated in two steps. First, lysozyme, PEG600DMA, and methacrylic acid were used as the template molecule, cross-linking monomer, and the functional monomer, respectively, in a UV free-radical polymerization process to synthesize a polymeric gel. Second, lysozyme was removed by enzymatic digestion. Non-imprinted polymer (NIP) was synthesized without lysozyme addition. To evaluate the preferential binding capability of MIP, lysozyme, RNase A, or a 50:50 mixture of lysozyme and RNase A was added to MIP and NIP and then released by digestion. It was found that when more lysozyme was added to the reaction mixture, the quantity of protein released from the polymer increased, reflecting more potential binding sites. Tests of MIP with a competitive binding mixture of lysozyme and RNase A showed the MIP preferentially bound a greater amount of lysozyme, up to 20 times more than RNase A. NIP bound only small amounts of both proteins and did not show a preference for binding either lysozyme or RNase A. These results demonstrate that lysozyme was successfully imprinted into the MIP by UV free-radical polymerization, and the fabricated MIP was able to preferentially bind its template protein.     

Preparation of Magnesium,Cobalt and Nickel Ferrite Nanoparticles from Metal Oxides using Deep Eutectic Solvents

Natural deep eutectic solvents (DESs) dissolve simple metal oxides and are used as a reaction medium to synthesize spinel‐type ferrite nanoparticles MFe₂O₄ (M=Mg, Zn, Co, Ni). The best results for phase‐pure spinel ferrites are obtained with the DES consisting of choline chloride (ChCl) and maleic acid. By employing DESs, the reactions proceed at much lower temperatures than usual for the respective solid‐phase reactions of the metal oxides and at the same temperatures as synthesis with comparable calcination processes using metal salts. The method therefore reduces the overall required energy for the nanoparticle synthesis. Thermogravimetric analysis shows that the thermolysis process of the eutectic melts in air occurs in one major step. The phase‐pure spinel‐type ferrite particles are thoroughly characterized by X‐ray diffraction, diffuse‐reflectance UV/Vis spectroscopy, and scanning electron microscopy. The properties of the obtained nanoparticles are shown to be comparable to those obtained by other methods, illustrating the potential of natural DESs for processing metal oxides.     

Controlled synthesis of responsive hydrogel nanostructures via microcontact printing and ATRP

Surfaces that are spatially functionalized with intelligent hydrogels, especially at the micro‐ and nanoscale, are of high interest in the diagnostic and therapeutic fields. Conventional methods of the semiconductor industry have been successfully employed for the patterning of hydrogels for various applications, but methods for fabricating precise 3 D patterns of hydrogels at the micro‐ and nanoscale over material surfaces remain limited. Herein, microcontact printing (µCP) followed by atom transfer radical polymerization (ATRP) was applied as a platform to synthesize temperature responsive poly(N‐isopropylacrylamide) hydrogels with varied network structures (e.g. different molecular weight crosslinkers) over gold surfaces. The XY control of the hydrogels was achieved using µCP, and the Z (thickness) control was achieved using ATRP. The controlled growth and the responsive behavior of hydrogels to temperature stimuli were characterized using Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). The results demonstrate that this platform allows for the controlled growth of hydrogel nanostructures using the controlled ATRP mechanism. It is also shown that the molecular weight of the crosslinker affects the rate of hydrogel growth. These PNIPAAm‐based crosslinked hydrogel patterns were also demonstrated to have a temperature‐dependent swelling response. Using this technique, it is possible to synthesize responsive hydrogel patterns over various surfaces for potential applications in the biomedical field. Copyright © 2009 John Wiley & Sons, Ltd.     

Entropy-driven formation of a chiral liquid-crystalline phase of helical filaments

We study the liquid-crystalline phase behavior of a concentrated suspension of helical flagella isolated from Salmonella typhimurium. Flagella are prepared with different polymorphic states, some of which have a pronounced helical character while others assume a rodlike shape. We show that the static phase behavior and dynamics of chiral helices are very different when compared to simpler achiral hard rods. With increasing concentration, helical flagella undergo an entropy-driven first order phase transition to a liquid-crystalline state having a novel chiral symmetry.     

Kondo scaling in the optical response of YbIn1-xAgxCu4

Theoretical work on Kondo systems predicts universality in the scaling of observable quantities with the Kondo temperature, T(K). Here we report infrared-frequency optical response measurements of the correlated system YbIn(1-x)AgxCu4. We observe that x-dependent variations in the frequency and strength of a low-energy excitation are related to the x-dependent Kondo temperature. Comparison of the inferred trends with existing theory and a model calculation provides a framework in which to view these experimental results as scaling phenomena arising from local-moment/conduction electron hybridization.     

Probing protein adsorption onto mercaptoundecanoic acid stabilized gold nanoparticles and surfaces by quartz crystal microbalance and zeta-potential measurements

The adsorption characteristics of three proteins [bovine serum albumin (BSA), myoglobin (Mb), and cytochrome c (CytC)] onto self-assembled monolayers of mercaptoundecanoic acid (MUA) on both gold nanoparticles (AuNP) and gold surfaces (Au) are described. The combination of quartz crystal microbalance measurements with dissipation (QCM-D) and pH titrations of the zeta-potential provide information on layer structure, surface coverage, and potential. All three proteins formed adsorption layers consisting of an irreversibly adsorbed fraction and a reversibly adsorbed fraction. BSA showed the highest affinity for the MUA/Au, forming an irreversibly adsorbed rigid monolayer with a side-down orientation and packing close to that expected in the jamming limit. In addition, BSA showed a large change in the adsorbed mass due to reversibly bound protein. The data indicate that the irreversibly adsorbed fraction of CytC is a monolayer structure, whereas the irreversibly adsorbed Mb is present in form of a bilayer. The observation of stable BSA complexes on MUA/AuNPs at the isoelectric point by zeta-potential measurements demonstrates that BSA can sterically stabilize MUA/AuNP. On the other hand, MUA/AuNP coated with either Mb or CytC formed a reversible flocculated state at the isoelectric point. The colloidal stability differences may be correlated with weaker binding in the reversibly bound overlayer in the case of Mb and CytC as compared to BSA.     

Sample Preparation and Diagnostic Methods for a Variety of Settings: A Comprehensive Review

Sample preparation is an essential step for nearly every type of biochemical analysis in use today. Among the most important of these analyses is the diagnosis of diseases, since their treatment may rely greatly on time and, in the case of infectious diseases, containing their spread within a population to prevent outbreaks. To address this, many different methods have been developed for use in the wide variety of settings for which they are needed. In this work, we have reviewed the literature and report on a broad range of methods that have been developed in recent years and their applications to point-of-care (POC), high-throughput screening, and low-resource and traditional clinical settings for diagnosis, including some of those that were developed in response to the coronavirus disease 2019 (COVID-19) pandemic. In addition to covering alternative approaches and improvements to traditional sample preparation techniques such as extractions and separations, techniques that have been developed with focuses on integration with smart devices, laboratory automation, and biosensors are also discussed.     

Angular- and temperature-dependent RSMR on myoglobin using 183W and 57Fe

Myoglobin crystals are investigated by Rayleigh scattering of Mössbauer radiation at T = 87 K and T = 300 K and angles up to sin(?)/λ = 0.44 Å^?1. The results are analysed in terms of normal modes.