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Characterization of nitrogen ion implanted InGaAs photoconductive devices is performed in both the electronic and optoelectronic regime. In the dark state, the optoelectronic device shows a dark resistance of a few kΩ and a wide electrical bandwidth in the RF domain. This large bandwidth is also confirmed in the illuminated state, optoelectronic autocorrelation experiments performed with ultra-short optical pulses allow us to measure the picosecond optoelectronic time response of the device. In the second part of the work, we investigate the potentiality of this component to be used in the photonic assisted heterodyne detection of RF modulated carriers for radio-over-fibre telecommunications. We demonstrate that this photoconductor, thanks to its properties, can be used to demodulate complex data modulation formats in such an experiment.

We demonstrate an optoelectronic mixer based on an ultrafast InGaAs photoconductive switch and a mode-locked semiconductor laser diode. The advantage of the switch is its relatively flat response curve in a wide frequency range of 1–67 GHz. The InP based quantum-dash mode-locked laser emitting in the 1550 nm wavelength range, serves as the source of the local oscillator frequency of 24.5 GHz. The proposed scheme is taking advantage of the low-linewidth of the pulsed laser source and can be used as a heterodyne mixer at the receiver side of a Radio-over-fiber network’s wireless link. We show the mixing performance through I-Q modulated data-stream downconversion and its improvement when the phase noise of the laser is reduced thanks to an optical feedback loop.

This article examines the reverberations in Russia of the Euromaidan protests and the fall of the Yanukovych regime in Ukraine. It shows how the events in Kyiv provoked a major crisis in the Russian nationalist movement, which was riven by vituperative denunciations, the ostracism of prominent activists, the breakdown of friendships, the rupture of alliances, and schisms within organizations. Focusing on pro-Kremlin nationalists and several tendencies of opposition nationalists, it argues that this turmoil was shaped by three factors. First, the Euromaidan provoked clashes between pro-Kremlin nationalists, who became standard-bearers of official anti-Euromaidan propaganda, and anti-Putin nationalists, who extolled the Euromaidan as a model for a revolution in Russia itself. Second, the events in Ukraine provoked ideological contention around issues of particular sensitivity to Russian nationalists, such as the competing claims of imperialism and ethnic homogeneity, and of Soviet nationalism and Russian traditionalism. And third, many nationalists were unprepared for the pace of events, which shifted rapidly from an anti-oligarchic uprising in Kyiv to a push for the self-determination of ethnic Russians in Crimean and southeast Ukraine. As a result, they were left in the uncomfortable position of appearing to collaborate with the oppressors of their compatriots.

This article examines the surprising revival of dissident principles and dissident modes of protest in the Russian opposition during the Putin-Medvedev “tandemocracy” (2008–12). Its focus is “Strategy-31,” a campaign of civil disobedience instigated by the radical activist Eduard Limonov. The first part of this article seeks to demonstrate how Strategy-31 employed what Charles Tilly terms a “repertoire of contention,” a set of performed actions and discursive practices, which had been inherited from the dissident rights-defenders. This repertoire both mimicked and transformed the dissidents” traditional forms of activism. By employing this repertoire and by explicitly identifying dissidents as his precursors, Limonov legitimised Strategy-31 and made it easier for his political rivals and ideological adversaries to join him in a common endeavor. The second part of this article shows how tensions within the dissident tradition contributed to the breakdown of the coalition of radicals and rights-defenders at the core of Strategy-31. To bolster his credibility as a crusader for constitutional rights, Limonov had courted the support of Lyudmila Alekseeva, a veteran dissident who headed the Moscow Helsinki Group. By joining Limonov as an applicant for Strategy-31, Alekseeva became a living link between its demonstrations and those of its dissident precursors. But Alekseeva and Limonov differed profoundly in their motives and their goals. These differences, which were skilfully exploited by the authorities, ultimately led to the collapse of Strategy-31.

Recently, biological roles of extracellular vesicles (which include among others exosomes, microvesicles and apoptotic bodies) have attracted substantial attention in various fields of biomedicine. Here we investigated the impact of sustained exposure of cells to the fluoroquinolone antibiotic ciprofloxacin on the released extracellular vesicles. Ciprofloxacin is widely used in humans against bacterial infections as well as in cell cultures against Mycoplasma contamination. However, ciprofloxacin is an inducer of oxidative stress and mitochondrial dysfunction of mammalian cells. Unexpectedly, here we found that ciprofloxacin induced the release of both DNA (mitochondrial and chromosomal sequences) and DNA-binding proteins on the exofacial surfaces of small extracellular vesicles referred to in this paper as exosomes. Furthermore, a label-free optical biosensor analysis revealed DNA-dependent binding of exosomes to fibronectin. DNA release on the surface of exosomes was not affected any further by cellular activation or apoptosis induction. Our results reveal for the first time that prolonged low-dose ciprofloxacin exposure leads to the release of DNA associated with the external surface of exosomes.

International audience; Optical processing of RF signals is demonstrated in this communication using photoswitches made from Nitrogen Implanted InGaAs. The sampling device shows an ultrafast picosecond response time while activated by ultra-short optical pulses or modulated optical beam centered at the wavelength of 1.55 µm. The optoelectronic device is embedded in a microwave coplanar waveguide which has a high electrical bandwidth allowing to process signals in the 1-67 GHz band. We investigate the potentiality of this component to be used either in photonic assisted sampling for future Analog to Digital Converters or in photonic assisted heterodyne detection of RF modulated carriers. Index Terms-Photoconductive sampling, Ion Implanted InGaAs, ultrafast electronics, metal-semiconductor-metal devices, Radio Over Fiber, photonic assisted data processing, heterodyne photomixer.

The interaction of the anti-adhesive coating, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its Arg-Gly-Asp (RGD) functionalized form, PLL-g-PEG-RGD, with the green tea polyphenol, epigallocatechin-gallate (EGCg) was in situ monitored. After, the kinetics of cellular adhesion on the EGCg exposed coatings were recorded in real-time. The employed plate-based waveguide biosensor is applicable to monitor small molecule binding and sensitive to sub-nanometer scale changes in cell membrane position and cell mass distribution; while detecting the signals of thousands of adhering cells. The combination of this remarkable sensitivity and throughput opens up new avenues in testing complicated models of cell-surface interactions. The systematic studies revealed that, despite the reported excellent antifouling properties of the coatings, EGCg strongly interacted with them, and affected their cell adhesivity in a concentration dependent manner. Moreover, the differences between the effects of the fresh and oxidized EGCg solutions were first demonstrated. Using a semiempirical quantumchemical method we showed that EGCg binds to the PEG chains of PLL-g-PEG-RGD and effectively blocks the RGD sites by hydrogen bonds. The calculations supported the experimental finding that the binding is stronger for the oxidative products. Our work lead to a new model of polyphenol action on cell adhesion ligand accessibility and matrix rigidity.

The mechanism of alternating deposition of oppositely charged gold nanoparticles (AuNPs) was investigated by optical waveguide lightmode spectroscopy (OWLS). OWLS allows monitoring of the kinetics of layer-by-layer (LbL) adsorption of positively and negatively charged nanoparticles in real time without using any labels so that the dynamics of layer formation can be revealed. Positively charged NPs that are already deposited on a negatively charged glass substrate strongly facilitate the adsorption of the negatively charged particles. The morphology of the adsorbed layer was also investigated with atomic force microscopy (AFM). AFM revealed that the interaction between oppositely charged particles results in the formation of NP clusters with sizes varying between 100 and 6000 NPs. The cluster size distribution is found to be an exponentially decaying function, and we propose a simple theory to explain this finding.

When various analytes and functional layers are deposited on the surface of optical waveguide based biochips one faces difficulties in correctly interpreting the experimental data. For example, the deposited layer can be highly ordered (lipid bilayers, oriented receptors etc.) or can have significant inhomogeneity both perpendicular and parallel to the sensor surface (adsorbed polymer films, living cells). The generally applied simple optical model, which treats the deposited analyte layers homogeneous, isotropic and usually relatively thin compared to the wavelength of light, therefore, fails in most of the practical cases. In the present contribution, we systematically investigate the limitations of the widely applied optical models, when the analyte layer on the sensing surface has a vertically inhomogeneous refractive index profile. As examples of more realistic density profiles, the step-index, linear, exponential, power law and Gaussian refractive index distributions on various types of waveguide biochips are investigated using analytical and numerical model calculations. The limitations and the possible errors of the homogeneous thin adlayer model are pointed out. It is shown that for all of the vertically inhomogeneous profiles the refractive index obtained from the homogeneous thin layer modeling underestimates the true averaged refractive index of the layer. The calculated thickness can be over or underestimated, even taking up negative values in some cases. This behavior is similar to what was observed for positively birefringent thin adlayers treated with the homogeneous and isotropic model. It is also shown that the surface mass coverages calculated using the thickness and refractive index obtained from the homogeneous and isotropic modeling underestimate the real coverage values. The above errors are smallest when the reverse waveguide sensor design is applied to investigate vertically inhomogeneous analytes.

A simple, reliable and cost-effective fluidic channel, fabricated by using double-sided pressure-sensitive tapes, is demonstrated here. A laser-cutting method is applied to engrave structures in sheets of the tapes. After peeling off the tape liners, the structures could be easily integrated at room temperature with label-free optical waveguide biochips without further modifications or additional processing steps. It is shown that the well-defined and controllable height of the channels is advantageous for stopped-flow measurements of analyte binding. The easy fabrication of a fully transparent integrated sensor unit – tape cuvette system is also demonstrated for parallel microscopic investigations. The transparent unit was used to on-line monitor the surface adhesion of Salmonella cells on poly-l-lysine-coated biochip surfaces, followed by the straightforward microscopic visualization of the adhered bacterial cells. The material of the double sided tape is stable in aqueous solutions. Furthermore, its material is biocompatible, making it ideal for biological applications. Excellent, stable and reversible bonding of the microstructured tapes to biocompatible plastic and glass is also demonstrated. The simplicity of the fabrication at ambient temperatures makes the developed processes appealing for lab-on-a-chip applications, particularly if the bonded biochips are precious.

This article examines the impact of the Initiative Group for the Defense of Human Rights in the USSR, the first Soviet human rights NGO. It argues that this group, which functioned for over six years as the principal public platform of Soviet dissidents, made an important contribution both to the subversion of totalitarianism and to the rise of the Soviet rights-defense movement. The Initiative Group overcame a longstanding taboo on the creation of public structures and spearheaded the resistance to the KGB’s most serious crackdown on the movement. It also shaped the methods and the ethics of Soviet rights-defenders. Although its members suffered severe repression, they deserve recognition for their contribution to the global human rights boom of the late 1970s. * Robert Horvath earned a B.A. and Ph.D. in History at the University of Melbourne in Australia. He currently holds an Australian Research Council fellowship at La Trobe University in Melbourne. He is the author of The Legacy of Soviet Dissent (Routledge, 2005) and Putin’s Preventive Counter-Revolution: Post-Soviet Authoritarianism and the Spectre of Velvet Revolution (Routledge, 2013). This research was supported by an Australian Research Council Future Fellowship (project number FT110100690). The author is indebted to the assistance and advice of Gennadii Kuzovkin from the Memorial Society, who helped to conduct interviews and offered many important insights. He is also grateful to: Roland Burke, who shared materials from his research in UN archives; Ed Kline, who made some important corrections; Emma Gilligan, Peter Reddaway, Aleksandr Daniel, Yurii Orlov and Natal’ya Kravchenko for illuminating discussion; and Sergei Kovalev, Aleksandr Lavut, and Pavel Litvinov for granting long interviews. He remains responsible for any remaining errors. Human Rights Quarterly 36 (2014) 147–175 © 2014 by The Johns Hopkins University Press Vol. 36 148 HUMAN RIGHTS QUARTERLY

Lactic acidosis is commonly observed in children following congenital heart surgery. Serum lactate is a surrogate measure of cardiac output and tissue oxygen delivery. Children and adolescents frequently have elevated lactate levels postoperatively without clinical signs of low cardiac output. Our objective was to evaluate children with postoperative lactic acidosis and to describe a distinct group of patients with lactic acidosis and low inotropic scores we named “benign” lactic acidosis. We conducted a retrospective chart review of 105 patients, 5 to 21 years old, who had undergone open-heart surgery from 05/2011 to 05/2013. Based on highest postoperative lactate levels (>4.4 mmol/L or 40 mg/dl) and inotrope scores (≥15) in the first 48 postoperative hours we defined three groups: classic lactic acidosis (elevated lactate and inotrope score, n = 9), benign lactic acidosis (elevated lactate and low inotrope score, n = 25) and a control group (low lactate and low inotrope score, n = 71). Lactic acidosis in the benign group was less pronounced and resolved earlier than in the classic group. The classic and benign groups had significantly elevated serum glucose. The classic group had significantly longer cardiopulmonary bypass time, time to extubation and hospital length of stay compared to the benign and control groups. The classic group had significantly lower systolic blood pressure, higher heart rate and central venous pressure, and lower urine output than the benign and control groups. Benign lactic acidosis is clinically distinct from classic lactic acidosis. It has faster resolution and patients exhibit stable postoperative hemodynamics with similar clinical outcomes as patients in the control group.

A high-throughput label-free resonant waveguide grating biosensor, the Epic BenchTop, was utilized to in situ monitor the adhesion process of cancer cells on Arg-Gly-Asp tripeptide displaying biomimetic polymer surfaces. Using highly adherent human cervical adenocarcinoma (HeLa) cells as a model system, cell adhesion kinetic data with outstanding temporal resolution were obtained. We found that pre-exposing the cells to various concentrations of the main extract of green tea, the (-)-epigallocatechin gallate (EGCG), largely affected the temporal evolution of the adhesion process. For unexposed and low dosed cells, sigmoid shaped spreading kinetics was recorded. Higher dose of EGCG resulted in a complete absence of the sigmoidal character, and displayed adsorption-like kinetics. By using the first derivatives of the kinetic curves, a simple model was developed to quantify the sigmoidal character and the transition from sigmoidal to adsorption-like kinetics. The calculations showed that the transition happened at EGCG concentration of around 60 μg/mL. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide end-point assay, we concluded that EGCG is cytostatic but not cytotoxic. The effect of EGCG was also characterized by flow cytometry. We concluded that, using the introduced label-free methodology, the shape of the cell adhesion kinetic curves can be used to quantify in vitro cell viability in a fast, cost-effective, and highly sensitive manner.

The field of extracellular vesicles is an exponentially growing segment of biomedical sciences. However, the problems of normalisation and quantification of extracellular vesicle samples have not been completely solved yet. Currently, extracellular vesicle samples are standardized on the basis of their protein content sometimes combined with determination of the particle number. However, even this combined approach may result in inaccuracy and overestimation of the extracellular vesicle concentration. Lipid bilayers are indispensable components of extracellular vesicles. Therefore, a lipidbased quantification, in combination with the determination of particle count and/or protein content, appears to be a straightforward and logical approach for the extracellular vesicle field. In this study we set the goal to improve the previously reported sulfo-phospho-vanillin total lipid assay. We introduced an aqueous phase liposome standard (DOPC) to replace the purified lipid standards in organic solvents (used commonly in previous studies). Furthermore, we optimized the concentration of the vanillin reagent in the assay. We found that elimination of organic solvents from the reaction mixture could abolish the background colour that interfered with the assay. Comparison of the optimised assay with a commercial lipid kit (based on the original sulfo-phospho-vanillin lipid assay) showed an increase of sensitivity by approximately one order of magnitude. Thus, here we report a quick, reliable and sensitive test that may fill an existing gap in extracellular vesicle standardisation. When using the optimised total lipid assay reported here, extracellular vesicle lipid measurements can be as easy as measuring proteins with a simple BCA test.

In this proof-of-principle study a label-free optical sensor is demonstrated to monitor the surface adhesion of extracellular vesicles secreted by live cells on to various extracellular matrix proteins.

International journal of molecular sciences 14(5), 9722-9736 (2013). doi:10.18154/RWTH-CONV-085528, Published by Molecular Diversity Preservation International, Basel

Here, we briefly discuss the past, present, and possible future of label-free optical biosensors in cell research, especially focusing on the kinetic monitoring of cellular adhesion. Currently available optical biosensors possess outstanding potentials still not rightfully recognized and still waiting to be fully exploited in the field of cell science. Thus, during the description we give special emphasis to the advantages that the state-of-the-art optical cell-based biosensors possess as compared to microscopeor force measurement-based techniques widely used to characterize cell adhesion. To name here only a few, they enable label-free detection close to a planar sensor surface, have high sensitivity, and generate superior quality kinetic data. Such information-rich kinetic data, in turn, can be analyzed in-depth and comparatively. To exemplify the importance of in-depth kinetic analysis, we review a recent study, in which the Epic BenchTop high-throughput optical biosensor was used to measure the dependence of cancer cell adhesion kinetics on the surface density of integrin ligands. Based on the kinetic data, a model enabling the label-free determination of the dissociation constant of the adhesion ligands bound to their native cell membrane receptors has been constructed. As an outlook, the perspectives of the technology is briefly discussed.

Complement receptors CR3 (CD11b/CD18) and CR4 (CD11c/CD18) belong to the family of beta2 integrins and are expressed mainly by myeloid cell types in humans. Previously, we proved that CR3 rather than CR4 plays a key role in phagocytosis. Here we analysed how CD11b and CD11c participate in cell adhesion to fibrinogen, a common ligand of CR3 and CR4, employing human monocytes, monocyte-derived macrophages (MDMs) and monocyte-derived dendritic cells (MDDCs) highly expressing CD11b as well as CD11c. We determined the exact numbers of CD11b and CD11c on these cell types by a bead-based technique, and found that the ratio of CD11b/CD11c is 1.2 for MDDCs, 1.7 for MDMs and 7.1 for monocytes, suggesting that the function of CD11c is preponderant in MDDCs and less pronounced in monocytes. Applying state-of-the-art biophysical techniques, we proved that cellular adherence to fibrinogen is dominated by CD11c. Furthermore, we found that blocking CD11b significantly enhances the attachment of MDDCs and MDMs to fibrinogen, demonstrating a competition between CD11b and CD11c for this ligand. On the basis of the cell surface receptor numbers and the measured adhesion strength we set up a model, which explains the different behavior of the three cell types.

Rarely, epidural catheters may fracture upon removal or insertion. Understanding some of the mechanical properties of epidural catheters, such as their tensile strength and how external factors (including temperature) can influence their strength, will aid physicians in making decisions if faced with an entrapped catheter. In the present study, we evaluated the impact in tensile strength when catheters are exposed to 37 ± 1°C, after the removal of the inner metal coil and after the injection of sterile saline through the catheter.We analyzed the tensile strength of a total of 120 catheters (19-gauge) from 3 different brands and materials. The reinforced epidural catheters were affixed to opposing, specially designed tensile test fixtures and then installed in an Applied Test System tensile test apparatus. We evaluated the strength of 10 catheters from different brands and materials for each of the following variables: at room temperature (control group), after the removal of the inner wire present in all the flexible catheters tested, injection of normal saline, and at 37 ± 1°C.When compared with their control groups, the Arrow catheter (2.85 kg) was shown to be superior to B-Braun (2.17 kg; P0.0001) and Smith catheters (2.33 kg; P0.0005). No statistical difference was noted between the Smith and B-Braun catheters (P = 0.39). When comparing catheters after wire removal against their respective control group, no statistical difference was noted. A decrease in tensile strength was noted in the B-Braun catheters (1.53 kg) when tested at 37°C (P ≤ 0.0001). In contrast, the Smith and the Arrow catheters did not show a statistically significant change when tested at 37°C (P = 1.0 and P = 0.063, respectively). After the injection of normal saline, the Arrow (2.33 kg) and the B-Braun (1.58 kg) catheters showed a decrease in tensile strength (P = 0.0010 and P = 0.0001, respectively).The current recommendation of injecting saline through an entrapped catheter resulted in a decrease in tensile strength of the Arrow and B-Braun catheters. A decrease in tensile strength also was noted in the B-Braun catheters when tested at 37°C. There is no benefit, at least in terms of tensile strength, in removing the wire or inner coil from any of the tested brands. The Smith catheter was the most resilient, showing no decrease in tensile strength at 37°C and after the injection of normal saline when compared with control.

We report a method enabling intensity-based readout for label-free cellular assays and realize a reader device with the same footprint as a microtiter plate. For unambiguous resonance intensity measurements in resonance waveguide grating (RWG) sensors, we propose to apply resonances near the substrate cutoff wavelength. This method was validated in bulk refractive index, surface bilayer and G protein-coupled receptor (GPCR) experiments. The significantly reduced size of the reader device opens new opportunities for easy integration into incubators or liquid handling systems.

Biomimetic coatings with cell-adhesion-regulating functionalities are intensively researched today. For example, cell-based biosensing for drug development, biomedical implants, and tissue engineering require that the surface adhesion of living cells is well controlled. Recently, we have shown that the bacterial flagellar protein, flagellin, adsorbs through its terminal segments to hydrophobic surfaces, forming an oriented monolayer and exposing its variable D3 domain to the solution. Here, we hypothesized that this nanostructured layer is highly cell-repellent since it mimics the surface of the flagellar filaments. Moreover, we proposed flagellin as a carrier molecule to display the cell-adhesive RGD (Arg-Gly-Asp) peptide sequence and induce cell adhesion on the coated surface. The D3 domain of flagellin was replaced with one or more RGD motifs linked by various oligopeptides modulating flexibility and accessibility of the inserted segment. The obtained flagellin variants were applied to create surface coatings inducing cell adhesion and spreading to different levels, while wild-type flagellin was shown to form a surface layer with strong anti-adhesive properties. As reference surfaces synthetic polymers were applied which have anti-adhesive (PLL-g-PEG poly( l -lysine)-graft-poly(ethylene glycol)) or adhesion inducing properties (RGD-functionalized PLL-g-PEG). Quantitative adhesion data was obtained by employing optical biochips and microscopy. Cell-adhesion-regulating coatings can be simply formed on hydrophobic surfaces by using the developed flagellin-based constructs. The developed novel RGD-displaying flagellin variants can be easily obtained by bacterial production and can serve as alternatives to create cell-adhesion-regulating biomimetic coatings. Statement of Significance In the present work, we show for the first time that - an oriented and dense monolayer of flagellin molecules mimics the surface of the bacterial flagellar filament. Consequently, the fabricated layer is completely cell repellent. - By genetically modifying flagellin, we incorporate cell adhesion regulating functionalities into this anti-adhesive coating. - We can easily tune the adhesion of living cells from completely cell repellent to highly adhesive.

The development of artificial surfaces which can regulate or trigger specific functions of living cells, and which are capable of inducing in vivo-like cell behaviors under in vitro conditions has been a long-sought goal over the past twenty years. In this work, an alternative, facile and cost-efficient method for mass-producible cellular templates is presented. The proposed methodology consists of a cost-efficient, two-step, all-wet technique capable of producing ZnO-based nanostructures on predefined patterns on a variety of substrates. ZnO—apart from the fact that it is a biocompatible material—was chosen because of its multifunctional nature which has rendered it a versatile material employed in a wide range of applications. Si, Si3N4, emulated microelectrode arrays and conventional glass cover slips were patterned at the micrometer scale and the patterns were filled with ZnO nanostructures. Using HeLa cells, we demonstrated that the fabricated nanotopographical features could promote guided cellular adhesion on the pre-defined micron-scale patterns only through nanomechanical cues without the need for further surface activation or modification. The basic steps of the micro/nanofabrication are presented and the results from the cell adhesion experiments are discussed, showing the potential of the suggested methodology for creating low-cost templates for engineered cellular networks.

Current robots can manipulate only surface-attached cells seriously limiting the fields of their application for single cell handling. We developed a computer vision-based robot applying a motorized microscope and micropipette to recognize and gently isolate intact individual cells for subsequent analysis, e.g., DNA/RNA sequencing in 1–2 nanoliters from a thin (~100 μm) layer of cell suspension. It can retrieve rare cells, needs minimal sample preparation and can be applied for virtually any tissue cell type. Combination of 1 μm positioning precision, adaptive cell targeting and below 1 nl liquid handling precision resulted in an unprecedented accuracy and efficiency in robotic single cell isolation. Single cells were injected either into the wells of a miniature plate with a sorting speed of 3 cells/min or into standard PCR tubes with 2 cells/min. We could isolate labeled cells also from dense cultures containing ~1,000 times more unlabeled cells by the successive application of the sorting process. We compared the efficiency of our method to that of single cell entrapment in microwells and subsequent sorting with the automated micropipette: the recovery rate of single cells was greatly improved.

Novel optical biosensors in direct interaction with living cells open new avenues in the detection of given cell types, including pathogenic microorganisms, and in the measurement of cytotoxicity of given xenobiotics, such as biothreat agents, on suitably selected cell types or lines. Evanescent optical field based biosensors emerging for such applications are reviewed, covering surface plasmon and waveguide based formats, imaging setup, employing optical waveguides, and digital holographic microscopy. Commercial technologies, along with main pathogenic microorganisms (Bacillus anthracis, Escherichia coli, Listeria monocytogenes, Campylobacter jejuni, etc.) as analytes and cell lines (native tissue and tumor cells) as cytotoxicity effect subjects are highlighted.

International audience; This work demonstrates the heterogenization of homogeneous water oxidation electrocatalysts in surface coatings produced by combining the substances with a suitable polyelectrolyte. The electrocatalysts i.e. Cu(ii)-branched peptide complexes involving a 2,3-l-diaminopropionic acid junction unit are heterogenized by building composite layers on indium-tin-oxide (ITO) electrode surface. Alternating deposition of the peptide complexes and poly(l-lysine) or poly(allylamine hydrochloride) were carried out in the presence of phosphate in a pH range of 7.5-10.5. Discussion of the results is divided to (1) characteristics of composite layer buildup and (2) electrocatalytic water oxidation and accompanying changes of these layers. For (1), optical waveguide lightmode spectroscopy (OWLS) has been applied to reveal the layer-by-layer formation of a Cu-ligand/polyelectrolyte/phosphate coating. The fabricated structures had a nanoporous topography (atomic force microscopy). As for (2), electrochemistry employing coated ITO substrates indicated improved water oxidation electrocatalysis vs. neat ITO and dependence of this improvement on the presence or absence of a histidine ligand in the deposited Cu(ii)-complexes equally, as observed in homogeneous systems. Electrochemical OWLS revealed changes in the coatings in operando, upon alternating positive-zero-positive etc. polarization: after some initial loss of the coating mass steady-state electrolysis was sustained by a compact and stable layer. According to X-ray photoelectron spectroscopy Cu remains in an N-donor ligand environment after electrolysis. © 2016 The Royal Society of Chemistry.

Titanate nanotubes were synthesized from TiO{sub 2} in alkaline medium by a conventional hydrothermal method (150 Degree-Sign C, 4.7 bar). To obtain hydrogen titanates, the as-prepared sodium titanates were treated with either HCl or H{sub 3}PO{sub 4} aqueous solutions. A simple synthesis procedure was devised for stable titanate nanotube sols without using any additives. These highly stable ethanolic sols can readily be used to prepare transparent titanate nanotube thin films of high quality. The resulting samples were studied by X-ray diffraction, N{sub 2}-sorption measurements, Raman spectroscopy, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. The comparative results of using two kinds of acids shed light on the superior thermal stability of the H{sub 3}PO{sub 4}-treated titanate nanotubes (P-TNTs). X-ray photoelectron spectroscopy revealed that P-TNTs contains P in the near-surface region and the thermal stability was enhanced even at a low ({approx}0.5 at%) concentration of P. After calcination at 500 Degree-Sign C, the specific surface areas of the HCl- and H{sub 3}PO{sub 4}-treated samples were 153 and 244 m{sup 2} g{sup -1}, respectively. The effects of H{sub 3}PO{sub 4} treatment on the structure, morphology and porosity of titanate nanotubes are discussed. - Graphical Abstract: TEM picture (left) showsmore » P-TNTs with diameters about 5-6 nm. Inset shows a stable titanate nanotube sol illuminated by a 532 nm laser beam. Due to the presence of the nanoparticles the way of the light is visible in the sol. Cross sectional SEM picture (right) as well as ellipsometry revealed the formation of optical quality P-TNT films with thicknesses below 50 nm. Highlights: Black-Right-Pointing-Pointer H{sub 3}PO{sub 4} treatment led to TNTs with high surface area even after calcination at 500 Degree-Sign C. Black-Right-Pointing-Pointer H{sub 3}PO{sub 4}-treated TNTs preserved their nanotube morphology up to 500 Degree-Sign C. Black-Right-Pointing-Pointer Stable TNT sols can be prepared by the peptization of TNT gels. Black-Right-Pointing-Pointer High-transparency TNT thin films of high quality were fabricated.« less

Conductive and highly transparent indium tin oxide (ITO) thin films were prepared on photosensitive glass substrates by the combination of sol–gel and spin-coating techniques. First, the substrates were coated with amorphous Sn-doped indium hydroxide, and these amorphous films were then calcined at 550∘C to produce crystalline and electrically conductive ITO layers. The resulting thin films were characterized by means of scanning electron microscopy, UV-Vis spectroscopy, X-ray photoelectron spectroscopy and spectroscopic ellipsometry. The measurements revealed that the ITO films were composed of spherical crystallites around 20 nm in size with mainly cubic crystal structure. The ITO films acted as antireflection coatings increasing the transparency of the coated substrates compared to that of the bare supports. The developed ITO films with a thickness of ∼170–330 nm were highly transparent in the visible spectrum with sheet resistances of 4.0–13.7 kΩ/sq. By coating photosensitive glass with ITO films, our results open up new perspectives in micro- and nano-technology, for example in fabricating conductive and highly transparent 3D microreactors.

A phase shifting optical waveguide interferometer is demonstrated for label-free evanescent wave biosensing in aqueous solutions. In the proposed configuration, the reference and measurement arms of the interferometer are combined inside an integrated optical Ta 2 O 5 waveguide using an ion implanted grating. Biomolecules adsorbing on the waveguide surface shift the phase in the measurement arm, which is modulated at the same time by a periodically relaxing liquid crystal phase modulator. It is demonstrated that by analyzing the periodic intensity response at the end facet of the waveguide, the phase shifts in the measurement arm can be monitored in real-time with a precision of 10 −4 rad. The high phase resolution allows the detection of surface adsorbed molecule densities below 1 pg/mm 2 without using any labeling or on-chip referencing. The instrument performance is demonstrated by monitoring in situ protein adsorption and affinity binding of low molecular weight pure biotin to an immobilized avidin layer.

In this study, we have reconstructed the statistical 3D structure of hundreds of nanometers thick surface immobilized flagellar filament protein layers in their native environment, in buffer solution. The protein deposition onto the surface activated Ta2O5 film was performed in a flow cell, and the immobilization process was followed by in situ spectroscopic ellipsometry. A multilayer optical model was developed, in that the protein layer was described by five effective medium sublayers. Applying this method, an in-depth analysis of the protein layer formation was performed. Based on the kinetics in the distribution of the surface mass density, the statistical properties of the filamentous film could be determined computationally as a function of the measurement time. It was also demonstrated that the 3D structure of the protein layer can be reconstructed based on the calculated in-depth mass density profile. The computational investigation revealed that the filaments can be classified into two individual groups in approximately equal ratio according to their orientation. In the first group the filaments are close to laying position, whereas in the second group they are in a standing position, resulting in a significantly denser sublayer close to the substrate than at a larger distance.

The kinetics of assembly of polyethylene glycol (PEG)-coated superparamagnetic Fe3O4 nanoparticles in aqueous suspension on planar Si(Ti)O2 surfaces have been determined using high-resolution optical waveguide lightmode spectroscopy (OWLS). Analysis of the results revealed that the initially uniform population was spontaneously transformed into two types of particles with significantly different adsorption behaviour.

An interferometric sensor based on gratings on a planar waveguide is introduced. The device combines the advantages of known interference-based waveguide sensors with the simplicity of grating couplers. In the presented configuration, two parallel and coherent light beams, laterally separated in the direction of mode propagation, are coupled into a planar waveguide through a grating. One of the coupled beams is phase modulated using a periodically relaxing liquid crystal modulator, resulting in a time varying intensity signal at the end face of the waveguide. Refractive index changes within the waveguide section between the two coupling regions are monitored by observing characteristic changes in the intensity signal.

Further efforts to correlate the topography of the bioactive structures of DPDPE and the deltorphins, two delta-opioid receptor active peptide families, are reported. A number of DPLPE-deltorphin chimeric peptides have been synthesized in which the C-terminal dipeptide delta-address of the deltorphins (-Val-GlyNH2, -Nle-GlyNH2) have been linked to the highly delta-opioid selective cyclic peptides DPDPE or DPLPE. These studies demonstrate that a major structural feature determining high potency of hybrid analogues is the chirality of the amino acid residue in position 5. The radioligand binding assays have revealed a decrease in potency (compared to DPDPE) at delta-receptors when the C-terminal dipeptides were added to DPDPE. On the other hand, chimeric peptides of DPLPE with these same C-terminal dipeptides retained high delta-selectivity and affinity. Similar results were obtained using the mouse vas deferens (MVD) and guinea pig ileum (GPI) bioassays. The importance of the hydrophilicity of amino acids in positions 2 and 5 for delta-selectivity is consistent with the previous finding for DPLPE and DPDPE. On the other hand, the replacement of phenylalanine-4 with p-chlorophenylalanine-4 did not increase delta-selectivity as in DPDPE. These findings suggest that the delta-receptor interacts with hybridized enkephalins and deltorphins somewhat differently than with DPDPE.

Recent experiments using a grating coupled low-index nanoporous silica supported monomode waveguide have demonstrated that living cells can cause heavy distortion of the grating coupler resonance lines, in some cases even leading to a separation into two resonance peaks. These findings stand in contrast to previously reported data, where simple peak broadening was observed during cell attachment and spreading using less sensitive waveguide designs. In order to explain these observations, we apply the local interference method to simulate the effects of inhomogeneity patterns on the surface of grating coupled planar optical waveguides and obtain the resonant peaks for the modes. It is shown that analyte inhomogeneities affect both the position and shape of the resonant peaks. Depending on the deposited cell or domain size, refractive index contrast and waveguide design, peak shift, peak deformations or peak splitting can be observed. On the basis of simulation data, characteristic parameters of the resonant peaks such as peak width at half maxima, overall width, central position and peak integral are connected for the first time to quantitative parameters of the inhomogeneity patterns; like analyte covered sensor area, surface averaged effective refractive index and domain size. Our results indicate that by careful investigations of the incoupling resonant peaks, quantitative information about sample inhomogeneities at the micrometer scale can be obtained, thus allowing for a new generation of simple, low cost, label free and imageless optical sensors, which are well suited for high throughput screening applications.

For much of the modern era, revolution served as a justification for gross violations of human rights. The sources of this “revolutionary privilege” are to be found in the historical experience of the Western world. Both the Jacobin tradition and Marxism contributed to the readiness of many Western intellectuals concerned with human rights to turn a blind eye to the atrocities of the Bolshevik revolution, its Stalinist aftermath, and a variety of Third World regimes. During the 1970s, East European dissidents, citizens of revolutionary societies, challenged this double-standard. The ensuing “Solzhenitsyn Effect” contributed not merely to the “human rights boom” of the era, but also to the emergence of a new, radical humanitarianism.

Here we describe the protocol and workflow for a label-free cell adhesion assay utilizing the highthroughput Epic BenchTop (BT) optical biosensor. We also describe how the dissociation constant for the binding between integrins in their native cell membrane and their ligands immobilized on the planar sensor surface can be determined from the biosensor data. To achieve this, cell adhesion has to be measured on surfaces having fine-tuned ligand densities. The present protocol can be applied to determine the dissociation constant of the binding between any matrix adhesion receptor embedded in its native cell membrane and its ligand, provided that a coating molecule with appropriate functionalization is available. The effect of drugs or other chemicals on this molecular interaction and subsequent cellular adhesion can be investigated in a straightforward way.

A wavelength-interrogated waveguide sensor system with a large wavelength range (≈60 nm) is presented. Dynamic measurements of changes in the refractive index of up to 0.33 refractive index units are demonstrated, without the need for mechanical adjustments during measurements. Furthermore, simultaneous detection of the in-coupling of both TE and TM polarization components is realized, which, for example, could be used for online monitoring of both thickness and refractive index of thin adlayers.