Experimental observation of repulsively bound magnons.

Stable composite objects, such as hadrons, nuclei, atoms, molecules and superconducting pairs, formed by attractive forces are ubiquitous in nature. By contrast, composite objects stabilized by means of repulsive forces were long thought to be theoretical constructions owing to their fragility in naturally occurring systems. Surprisingly, the formation of bound atom pairs by strong repulsive interactions has been demonstrated experimentally in optical lattices1. Despite this success, repulsively bound particle pairs were believed to have no analogue in condensed matter owing to strong decay channels. Here we present spectroscopic signatures of repulsively bound three-magnon states and bound magnon pairs in the Ising-like chain antiferromagnet BaCo2V2O8. In large transverse fields, below the quantum critical point, we identify repulsively bound magnon states by comparing terahertz spectroscopy measurements to theoretical results for the Heisenberg-Ising chain antiferromagnet, a paradigmatic quantum many-body model2-5. Our experimental results show that these high-energy, repulsively bound magnon states are well separated from continua, exhibit notable dynamical responses and, despite dissipation, are sufficiently long-lived to be identified. As the transport properties in spin chains can be altered by magnon bound states, we envision that such states could serve as resources for magnonics-based quantum information processing technologies6-8.

Eu(O2 C-C≡C-CO2 ): An EuII Containing Anhydrous Coordination Polymer with High Stability and Negative Thermal Expansion.

Anhydrous EuII -acetylenedicarboxylate (EuADC; ADC2- = - O2 C-C≡C-CO2 - ) was synthesized by reaction of EuBr2 with K2 ADC or H2 ADC in degassed water under oxygen-free conditions. EuADC crystallizes in the SrADC type structure (I41 /amd, Z=4) forming a 3D coordination polymer with a diamond-like arrangement of Eu2+ nodes (msw topology including the connecting ADC2- linkers). Deep orange coloured EuADC is stable in air and starts decomposing upon heating in an argon atmosphere only at 440 °C. Measurements of the magnetic susceptibilities (µeff =7.76 µB ) and 151 Eu Mössbauer spectra (δ=-13.25 mm s-1 at 78 K) confirm the existence of Eu2+ cations. Diffuse reflectance spectra indicate a direct optical band gap of Eg =2.64 eV (470 nm), which is in accordance with the orange colour of the material. Surprisingly, EuADC does not show any photoluminescence under irradiation with UV light of different wavelengths. Similar to SrADC, EuADC exhibits a negative thermal volume expansion below room temperature with a volume expansion coefficient αV =-9.4(12)×10-6  K-1 .

BN- and BO-Doped Inorganic-Organic Hybrid Polymers with Sulfoximine Core Units.

While polysulfones constitute a class of well-established, highly valuable applied materials, knowledge about polymers based on the related sulfoximine group is very limited. We have employed functionalized diaryl sulfoximines and a p-phenylene bisborane as building blocks for unprecedented BN- and BO-doped alternating inorganic-organic hybrid copolymers. While the former were accessed by a facile silicon/boron exchange protocol, the synthesis of polymers with main-chain B-O linkages was achieved by salt elimination.

Poly(p-phenylene iminoborane): A Boron-Nitrogen Analogue of Poly(p-phenylene vinylene).

Substitution of selected CC units in π-conjugated organic frameworks by their isoelectronic and isosteric BN units (BN/CC isosterism) has proven to be a successful concept for the development of BN-doped polycyclic aromatic hydrocarbons (PAHs) with intriguing properties and functions. The first examples have just demonstrated the applicability of this approach to polymer chemistry. Herein, we present the synthesis and comprehensive characterization of the first poly(p-phenylene iminoborane). This novel inorganic-organic hybrid polymer can be regarded as a BN analogue of the well-known poly(p-phenylene vinylene) (PPV). Photophysical investigations on the polymer and a series of model oligomers provide clear evidence of some π-conjugation across the B=N bonds and extension of the conjugation path with increasing chain length. TD-DFT calculations provide deeper insight into the electronic structure of the new materials.

Dehydrocoupling and Silazane Cleavage Routes to Organic-Inorganic Hybrid Polymers with NBN Units in the Main Chain.

Despite the great potential of both π-conjugated organoboron polymers and BN-doped polycyclic aromatic hydrocarbons in organic optoelectronics, our knowledge of conjugated polymers with B-N bonds in their main chain is currently scarce. Herein, the first examples of a new class of organic-inorganic hybrid polymers are presented, which consist of alternating NBN and para-phenylene units. Polycondensation with B-N bond formation provides facile access to soluble materials under mild conditions. The photophysical data for the polymer and molecular model systems of different chain lengths reveal a low extent of π-conjugation across the NBN units, which is supported by DFT calculations. The applicability of the new polymers as macromolecular polyligands is demonstrated by a cross-linking reaction with Zr(IV) .

Characterization of oxygen transfer in vertical microbubble columns for aerobic biotechnological processes.

This paper presents the applicability of a microtechnologically fabricated microbubble column as a screening tool for submerged aerobic cultivation. Bubbles in the range of a few hundred micrometers in diameter were generated at the bottom of an upright-positioned microdevice. The rising bubbles induced the circulation of the liquid and thus enhanced mixing by reducing the diffusion distances and preventing cells from sedimentation. Two differently sized nozzles (21 × 40 µm(2) and 53 × 40 µm(2) in cross-section) were tested. The gas flow rates were adjustable, and the resulting bubble sizes and gas holdups were investigated by image analysis. The microdevice features sensor elements for the real-time online monitoring of optical density and dissolved oxygen. The active aeration of the microdevice allowed for a flexible oxygen supply with mass transfer rates of up to 0.14 s(-1). Slightly higher oxygen mass transfer rates and a better degassing were found for the microbubble column equipped with the smaller nozzle. To validate the applicability of the microbubble column for aerobic submerged cultivation processes, batch cultivations of the model organism Saccharomyces cerevisiae were performed, and the specific growth rate, oxygen uptake rate, and yield coefficient were investigated.

Preliminary results of anti-inflammatory cytokine concentrations predicting therapy outcome in panic disorder.

Background: Patients with panic disorder (PD) show alterations of the immune reactivity to acute stress, which could serve as a marker for effective treatment. Nevertheless, the effect of immune reactivity under acute stress before treatment on therapy outcome remains unclear. Methods: A total of N = 16 PD patients performed the Trier Social Test. Blood sample collection of anti-inflammatory cytokine IL-10 accompanied the TSST. The Mobility Inventory was handed out for the assessment of avoidance behavior before and after treatment. Area under the curve with respect to the ground (AUCG) and increase (AUCI) were calculated for assessed cytokine levels and were used as predictors for therapy outcome in regression analyses. Results: AUCG significantly predicts avoidance behavior in company after treatment (ß = -0.007, p = .033) but not avoidance behavior alone (ß = -0.003, p = .264). AUCI does not significantly predict therapy outcome. Conclusion: Higher concentrations of anti-inflammatory cytokine IL-10 under acute stress before treatment predicts less avoidance behavior in company after therapy. Immune markers seem to play a crucial role in the maintenance of mental disorders such as PD. Underlying mechanisms and IL-10 as a marker for individualized treatments should be investigated in future studies.

Microfluidic System for In Vivo-Like Drug Permeation Studies with Dynamic Dilution Profiles.

Automated biomimetic systems for the preclinical testing of drugs are of great interest. Here, an in vitro testing platform for in vivo adapted drug absorption studies is presented. It has been designed with a focus on easy handling and the usability of established cell cultivation techniques in standard well plate inserts. The platform consists of a microfluidic device, which accommodates a well plate insert with pre-cultivated cells, and provides a fluid flow with dynamic drug dilution profiles. A low-cost single-board computer with a touchscreen was used as a control unit. This provides a graphical user interface, controls the syringe pump flow rates, and records the transepithelial electrical resistance. It thereby enables automated parallel testing in multiple devices at the same time. To demonstrate functionality, an MDCK cell layer was used as a model for an epithelial barrier for drug permeation testing. This confirms the possibility of performing absorption studies on barrier tissues under conditions close to those in vivo. Therefore, a further reduction in animal experiments can be expected.

Accessible methods for the dynamic time-scale decomposition of biochemical systems.

MOTIVATION: The growing complexity of biochemical models asks for means to rationally dissect the networks into meaningful and rather independent subnetworks. Such foregoing should ensure an understanding of the system without any heuristics employed. Important for the success of such an approach is its accessibility and the clarity of the presentation of the results. RESULTS: In order to achieve this goal, we developed a method which is a modification of the classical approach of time-scale separation. This modified method as well as the more classical approach have been implemented for time-dependent application within the widely used software COPASI. The implementation includes different possibilities for the representation of the results including 3D-visualization. AVAILABILITY: The methods are included in COPASI which is free for academic use and available at www.copasi.org. CONTACT: irina.surovtsova@bioquant.uni-heidelberg.de SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Generalized Anderson's theorem for superconductors derived from topological insulators.

A well-known result in unconventional superconductivity is the fragility of nodal superconductors against nonmagnetic impurities. Despite this common wisdom, Bi2Se3-based topological superconductors have recently displayed unusual robustness against disorder. Here, we provide a theoretical framework that naturally explains what protects Cooper pairs from strong scattering in complex superconductors. Our analysis is based on the concept of superconducting fitness and generalizes the famous Anderson's theorem into superconductors having multiple internal degrees of freedom with simple assumptions such as the Born approximation. For concreteness, we report on the extreme example of the Cu x (PbSe)5(BiSe3)6 superconductor. Thermal conductivity measurements down to 50 mK not only give unambiguous evidence for the existence of nodes but also reveal that the energy scale corresponding to the scattering rate is orders of magnitude larger than the superconducting energy gap. This provides the most spectacular case of the generalized Anderson's theorem protecting a nodal superconductor.

Evidence for polarized nanoregions from the domain dynamics in multiferroic LiCuVO4.

LiCuVO4 is a model system of a 1D spin-1/2 chain that enters a planar spin-spiral ground state below its Néel temperature of 2.4 K due to competing nearest and next nearest neighbor interactions. The spin-spiral state is multiferroic with an electric polarization along the a axis which has been proposed to be caused purely by the spin supercurrent mechanism. With external magnetic fields in c direction TN can be suppressed down to 0 K at 7.4 T. Here we report dynamical measurements of the polarization from P(E)-hysteresis loops, magnetic field dependent pyro-current and non-linear dielectric spectroscopy as well as thermal expansion and magnetostriction measurements at very low temperatures. The multiferroic transition is accompanied by strong anomalies in the thermal expansion and magnetostriction coefficients and we find slow switching times of electric domain reversal. Both observations suggest a sizable magnetoelastic coupling in LiCuVO4. By analyzing the non-linear polarization dynamics we derive domain sizes in the nm range that are probably caused by Li defects.

Stress hormone response to the DEX-CRH test and its relation to psychotherapy outcome in panic disorder patients with and without agoraphobia.

This study tested whether the hormonal stress response to the DEX-CRH test may be predictive of the psychotherapy success for panic disorder (PD). Thirty-four patients diagnosed either with agoraphobia with PD or PD without agoraphobia were subjected to cognitive behavioural therapy (CBT). Patients (pre-therapy) and healthy volunteers were exposed to the DEX-CRH test. Blood samples were taken for cortisol and adrenocorticotropic hormone (ACTH) assessment. Established panic-specific questionnaires were handed out for the pre-therapy and post-therapy evaluation of disease severity (with reference to panic beliefs and agoraphobic cognitions, fear of bodily sensations, agoraphobic avoidance behaviour). Repeated measures ANCOVA were conducted for the analysis of the pre-therapy hormonal response, and Pearson's correlation analysis to test for associations with the psychotherapy outcome. Data analyses revealed large effect sizes for CBT in the clinical measures (η2 ≥ 0.321), main effects of time for cortisol and ACTH with no differences between both groups, and significant associations between cortisol release and agoraphobic cognitions for the patients. PD diagnosis had no impact on the hormonal response. However, those patients with higher cortisol release showed less improvement after CBT (significantly for agoraphobic cognitions). Clinical implications of these findings are the prediction of the therapy success from a potential endocrine correlate whose persistency (if assessed repeatedly) during the treatment may predict (non-)response to the current treatment, possibly representing a decision support for a change in treatment to avoid the continuation of an inefficient treatment.

Novel strategies for the formulation and processing of poorly water-soluble drugs.

Low aqueous solubility of active pharmaceutical ingredients presents a serious challenge in the development process of new drug products. This article provides an overview on some of the current approaches for the formulation of poorly water-soluble drugs with a special focus on strategies pursued at the Center of Pharmaceutical Engineering of the TU Braunschweig. These comprise formulation in lipid-based colloidal drug delivery systems and experimental as well as computational approaches towards the efficient identification of the most suitable carrier systems. For less lipophilic substances the preparation of drug nanoparticles by milling and precipitation is investigated for instance by means of microsystem-based manufacturing techniques and with special regard to the preparation of individualized dosage forms. Another option to overcome issues with poor drug solubility is the incorporation into nanospun fibers.

Effects of the cortisol stress response on the psychotherapy outcome of panic disorder patients.

BACKGROUND: A proportion of patients with panic disorder (PD) fail to show a remission after psychotherapy. Biological correlates of psychotherapy non-response have rarely been described in the literature. The aim of the present study was to research the relationship between the cortisol stress response and the psychotherapy outcome in PD patients. METHODS: Twenty-eight PD patients (20 females, mean age±SD: 35.71±13.18) seeking psychological treatment for PD and n=32 age- and sex-matched healthy control participants (21 females, aged 34.66±12.07) participated in this study. The patients underwent five weeks of cognitive behavioural therapy (CBT). Within the first two weeks of the CBT, both study groups were confronted with the Trier Social Stress Test (TSST). Blood sampling for cortisol and adrenocorticotropic hormone (ACTH) evaluation as well as fear-rating (Visual Analogue Scale; Primary Appraisal and Secondary Appraisal Questionnaire, PASA) accompanied the TSST. The global severity of PD (Panic & Agoraphobia Scale; PAS), agoraphobic cognitions (Agoraphobic Cognitions Questionnaire; ACQ), fear of bodily sensations (Bodily Sensations Questionnaire; BSQ), agoraphobic avoidance (Mobility Inventory; MI), and depressiveness (Beck Depression Inventory; BDI) were assessed before and after the CBT (except the BDI). RESULTS: The statistical analysis revealed significant main effects of time for cortisol and the ACTH concentration in response to the TSST, independently of the study group. 42.9% of the PD patients and 65.6% of the healthy control participants showed a cortisol stress response to the TSST≥55.2nmol/l (descriptive finding). The data showed a significant inverse association of the TSST cortisol stress response with the MI total score when accompanied. Further, a significant association of the PASA subjective level of fear and the BSQ as well as a trend for an association of the PASA with the ACQ were observed. CONCLUSION: Consistent with prior research, we could replicate findings of decreased cortisol concentrations in the PD patients in comparison to the healthy control participants. Furthermore, our findings agree with previous data showing an association of the attenuated cortisol stress response with the psychotherapy non-response. In the present sample, those patients with the lowest cortisol concentrations showed the least improvement in agoraphobic avoidance after psychotherapy. The patients with the highest level of fear showed the most improvement in fear of bodily sensations. Study limitations as well as implications for future studies will be discussed.

Quantum criticality in the spin-1/2 Heisenberg chain system copper pyrazine dinitrate.

Low-dimensional quantum magnets promote strong correlations between magnetic moments that lead to fascinating quantum phenomena. A particularly interesting system is the antiferromagnetic spin-1/2 Heisenberg chain because it is exactly solvable by the Bethe-Ansatz method. It is approximately realized in the magnetic insulator copper pyrazine dinitrate, providing a unique opportunity for a quantitative comparison between theory and experiment. We investigate its thermodynamic properties with a particular focus on the field-induced quantum phase transition. Thermal expansion, magnetostriction, specific heat, magnetization, and magnetocaloric measurements are found to be in excellent agreement with exact Bethe-Ansatz predictions. Close to the critical field, thermodynamics obeys the expected quantum critical scaling behavior, and in particular, the magnetocaloric effect and the Grüneisen parameters diverge in a characteristic manner. Beyond its importance for quantum magnetism, our study establishes a paradigm of a quantum phase transition, which illustrates fundamental principles of quantum critical thermodynamics.

Miniaturized osmotic pump for oromucosal drug delivery with external readout station.

We report on a miniaturized, exchangeable drug delivery cartridge for Parkinson's Disease which is integrated in a partial removable prosthesis. An osmotic pumping principle uses saliva to release constantly a separately stored drug to the buccal mucosa, thus avoiding first pass metabolism and drug plasma level fluctuations. Therapeutic relevant information and fill level of the cartridge can be determined before and after usage with an external readout station. The selected material combinations of the cartridge fulfill both, functional and regulatory aspects as well as requirements for assembly and packaging, e.g. thermal fusion bonding, solvent bonding and capillary stop bonding. By using the cartridge, highly precise release rates over 97% of its storage capacity with a rate deviation of only 1.1% can be achieved.