The Mean Single Molecule Rate (mSMR) in the Analysis of Fluorescence Fluctuations: Measurements on DNA Mixtures of Defined Composition.

We present a method for the evaluation of fluorescence fluctuations on the basis of Mandel's Q parameter, using sampling time-dependent factorial cumulants. By relating the Q parameter to the sampling time, we obtain the mean single molecule rate (mSMR), an easy to interpret expression that provides both brightness and diffusion information. The model is suitable for the widely used confocal setups with single photon excitation and a single detection channel. We present a way to correct the mSMR for afterpulsing, dead time and background noise. To account for photokinetic effects at short sampling times, we expand the model by a simple on/off isomerization term, which is similar to the well-known triplet model. The functionality of the mSMR is shown using Monte Carlo simulations. The correction mechanisms and the experimental applicability of the model are then demonstrated by DNA measurements of defined composition. By systematically analyzing DNA mixtures, we can show that at large sampling times, the mSMR correctly describes the single molecule brightness rates and the diffusive properties of DNA molecules. At short sampling times, the photokinetic effects of isomerization are accurately described by the mSMR model. Since additionally the mSMR can easily be corrected for measurement artefacts such as detector dead time, afterpulsing and background noise, this is a valuable advantage over the standard method of fluorescence correlation spectroscopy.

Quantum Critical Dynamics of a Heisenberg-Ising Chain in a Longitudinal Field: Many-Body Strings versus Fractional Excitations.

We report a high-resolution terahertz spectroscopic study of quantum spin dynamics in the antiferromagnetic Heisenberg-Ising spin-chain compound BaCo_{2}V_{2}O_{8} as a function of temperature and longitudinal magnetic field. Confined spinon excitations are observed in an antiferromagnetic phase below T_{N}≃5.5 K. In a field-induced gapless phase above B_{c}=3.8 T, we identify many-body string excitations as well as low-energy fractional psinon or antipsinon excitations by comparing to Bethe ansatz calculations. In the vicinity of B_{c}, the high-energy string excitations are found to have a dominant contribution to the spin dynamics as compared with the fractional excitations.

Interplay of Electronic and Spin Degrees in Ferromagnetic SrRuO_{3}: Anomalous Softening of the Magnon Gap and Stiffness.

The magnon dispersion of ferromagnetic SrRuO_{3} was studied by inelastic neutron scattering experiments on single crystals as a function of temperature. Even at low temperature the magnon modes exhibit substantial broadening pointing to strong interaction with charge carriers. We find an anomalous temperature dependence of both the magnon gap and the magnon stiffness, which soften upon cooling in the ferromagnetic phase. Both effects trace the temperature dependence of the anomalous Hall effect and can be attributed to the impact of Weyl points, which results in the same relative renormalization in the spin stiffness and magnon gap.

Quantum Criticality of an Ising-like Spin-1/2 Antiferromagnetic Chain in a Transverse Magnetic Field.

We report on magnetization, sound-velocity, and magnetocaloric-effect measurements of the Ising-like spin-1/2 antiferromagnetic chain system BaCo_{2}V_{2}O_{8} as a function of temperature down to 1.3 K and an applied transverse magnetic field up to 60 T. While across the Néel temperature of T_{N}∼5 K anomalies in magnetization and sound velocity confirm the antiferromagnetic ordering transition, at the lowest temperature the field-dependent measurements reveal a sharp softening of sound velocity v(B) and a clear minimum of temperature T(B) at B_{⊥}^{c,3D}=21.4 T, indicating the suppression of the antiferromagnetic order. At higher fields, the T(B) curve shows a broad minimum at B_{⊥}^{c}=40 T, accompanied by a broad minimum in the sound velocity and a saturationlike magnetization. These features signal a quantum phase transition, which is further characterized by the divergent behavior of the Grüneisen parameter Γ_{B}∝(B-B_{⊥}^{c})^{-1}. By contrast, around the critical field, the Grüneisen parameter converges as temperature decreases, pointing to a quantum critical point of the one-dimensional transverse-field Ising model.

pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O.

The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical composition and thickness of inorganic passivation shells and the chemical nature and number of surface ligands as well as the strength of their bonds to surface atoms. The latter is particularly important for CdTe NCs, which - together with alloyed CdxHg1-xTe - are the only SC NCs that can be prepared in water in high quality without the need for an additional inorganic passivation shell. Aiming at a better understanding of the role of stabilizing ligands for the control of the application-relevant fluorescence features of SC NCs, we assessed the influence of two of the most commonly used monodentate thiol ligands, thioglycolic acid (TGA) and mercaptopropionic acid (MPA), on the colloidal stability, photoluminescence (PL) quantum yield (QY), and PL decay behavior of a set of CdTe NC colloids. As an indirect measure for the strength of the coordinative bond of the ligands to SC NC surface atoms, the influence of the pH (pD) and the concentration on the PL properties of these colloids was examined in water and D2O and compared to the results from previous dilution studies with a set of thiol-capped Cd1-xHgxTe SC NCs in D2O. As a prerequisite for these studies, the number of surface ligands was determined photometrically at different steps of purification after SC NC synthesis with Ellman's test. Our results demonstrate ligand control of the pH-dependent PL of these SC NCs, with MPA-stabilized CdTe NCs being less prone to luminescence quenching than TGA-capped ones. For both types of CdTe colloids, ligand desorption is more pronounced in H2O compared to D2O, underlining also the role of hydrogen bonding and solvent molecules.

Spin-Orbital Excitation Continuum and Anomalous Electron-Phonon Interaction in the Mott Insulator LaTiO_{3}.

Raman scattering experiments on stoichiometric, Mott-insulating LaTiO_{3} over a wide range of excitation energies reveal a broad electronic continuum which is featureless in the paramagnetic state, but develops a gap of ~800 cm^{-1} upon cooling below the Néel temperature T_{N}=146 K. In the antiferromagnetic state, the spectral weight below the gap is transferred to well-defined spectral features due to spin and orbital excitations. Low-energy phonons exhibit pronounced Fano anomalies indicative of strong interaction with the electron system for T>T_{N}, but become sharp and symmetric for T

Cellular uptake of coumarin-6 under microfluidic conditions into HCE-T cells from nanoscale formulations.

UNLABELLED: In vitro studies of ocular bioavailability of active pharmaceutical ingredients (API) from colloidal drug delivery systems do not consider physiological shear stress generated by eyelid wiping and tear flow. The present study introduces a live cell imaging approach which enables the investigation of model drug uptake from various formulations under shear stress by using custom-made microchannels for the cultivation of human corneal epithelial cells (HCE-T). Coumarin-6 (C-6) was used as a model API incorporated into solid lipid nanoparticles and liposomes, and as an aqueous crystalline suspension. Confocal laser scanning microscopy visualized C-6 uptake into HCE-T cells in a time-resolved manner with an applied shear stress of 0.1 Pa. Static conditions were also studied for comparative purposes. Additionally, solid lipid nanoparticles (SLN) were labeled with a fluorescent phospholipid to check whether C-6 uptake was associated with SLN incorporation into the cells. RESULTS: Intact SLN were not incorporated into the cells, i.e., C-6 was passively redistributed from SLN to lipophilic cellular compartments. C-6 was enriched up to a given limit in HCE-T cells within 5 min of contact with the dispersions both under static and under flow conditions. The C-6 delivery rate from liposomes was superior to that from SLN whereby the suspension exhibited the lowest rate. C-6 release rates were comparable for static and flow conditions. Alternate flushing with formulations and buffer revealed that cells accumulated C-6. The results suggest that combining microfluidics with live cell imaging provides a valuable option for in vitro studies of ocular drug delivery.

Spin-1/2 XXZ chain system Cs2CoCl4 in a transverse magnetic field.

Comparing high-resolution specific heat and thermal expansion measurements to exact finite-size diagonalization, we demonstrate that Cs(2)CoCl(4) for a magnetic field along the crystallographic b axis realizes the spin-1/2 XXZ chain in a transverse field. Exploiting both thermal as well as virtual excitations of higher crystal-field states, we find that the spin chain is in the XY limit with an anisotropy J(z)/J[perpindicular] ≈ 0.12, substantially smaller than previously believed. A spin-flop Ising quantum phase transition occurs at a critical field of µ(0)H(b)(cr) ≈ 2 T before around 3.5 T the description in terms of an effective spin-1/2 chain becomes inapplicable.

Fluid-structure interactions of peripheral arteries using a coupled in silico and in vitro approach.

Vascular compliance is considered both a cause and a consequence of cardiovascular disease and a significant factor in the mid- and long-term patency of vascular grafts. However, the biomechanical effects of localised changes in compliance cannot be satisfactorily studied with the available medical imaging technologies or surgical simulation materials. To address this unmet need, we developed a coupled silico-vitro platform which allows for the validation of numerical fluid-structure interaction results as a numerical model and physical prototype. This numerical one-way and two-way fluid-structure interaction study is based on a three-dimensional computer model of an idealised femoral artery which is validated against patient measurements derived from the literature. The numerical results are then compared with experimental values collected from compliant arterial phantoms via direct pressurisation and ring tensile testing. Phantoms within a compliance range of 1.4-68.0%/100 mmHg were fabricated via additive manufacturing and silicone casting, then mechanically characterised via ring tensile testing and optical analysis under direct pressurisation with moderately statistically significant differences in measured compliance ranging between 10 and 20% for the two methods. One-way fluid-structure interaction coupling underestimated arterial wall compliance by up to 14.7% compared with two-way coupled models. Overall, Solaris™ (Smooth-On) matched the compliance range of the numerical and in vivo patient models most closely out of the tested silicone materials. Our approach is promising for vascular applications where mechanical compliance is especially important, such as the study of diseases which commonly affect arterial wall stiffness, such as atherosclerosis, and the model-based design, surgical training, and optimisation of vascular prostheses.

Dimerization and charge order in hollandite K2V8O16.

The metal-insulator transition occurring in hollandite K2V8O16 has been studied by means of neutron and x-ray diffraction as well as by thermodynamic and electron-spin resonance measurements. The complete analysis of the crystal structure in the distorted phase allows us to identify dimerization as the main distortion element in insulating K2V8O16. At low-temperature, half of the V chains are dimerized perfectly explaining the suppression of magnetic susceptibility due to the formation of spin singlets. The dimerization is accompanied by the segregation of charges into chains.

1.5 °C degrowth scenarios suggest the need for new mitigation pathways.

1.5 °C scenarios reported by the Intergovernmental Panel on Climate Change (IPCC) rely on combinations of controversial negative emissions and unprecedented technological change, while assuming continued growth in gross domestic product (GDP). Thus far, the integrated assessment modelling community and the IPCC have neglected to consider degrowth scenarios, where economic output declines due to stringent climate mitigation. Hence, their potential to avoid reliance on negative emissions and speculative rates of technological change remains unexplored. As a first step to address this gap, this paper compares 1.5 °C degrowth scenarios with IPCC archetype scenarios, using a simplified quantitative representation of the fuel-energy-emissions nexus. Here we find that the degrowth scenarios minimize many key risks for feasibility and sustainability compared to technology-driven pathways, such as the reliance on high energy-GDP decoupling, large-scale carbon dioxide removal and large-scale and high-speed renewable energy transformation. However, substantial challenges remain regarding political feasibility. Nevertheless, degrowth pathways should be thoroughly considered.

Rare earth elements recovery from secondary wastes by solid-state chlorination and selective organic leaching.

Processing of end-of-life products (EoL) containing rare earth elements (REE) has gained increasing importance in recent years with the aim of avoiding supply risks. In addition, circular economy renders complete recirculation of technology metals mandatory. Fluorescent lamp wastes are an important source for REE recovery since they contain significant amounts, up to 55 wt%, of Y and Eu in red phosphors. For these purposes, solid-state chlorination (SSC) is an economically attractive alternative to wet acid leaching treatment, which profits from a considerable reduction of chemicals consumption and process costs. Chlorination takes place with dry HCl(g) produced from thermal decomposition of NH4Cl(s), not only converting the REE content of the Hg-free phosphor waste into water soluble REE metal chlorides, but also avoiding the implications of aqueous complex chemistry of REE. To establish an industrial process viable on a commercial scale, the SSC process has been optimized by (i) using a design of experiment (DOE) varying temperature, residence time, and gNH4Cl/gsolid ratio and (ii) improved leaching of the chlorinated metals with an organic mixture selective for REE. As a result, 95.7% of the Y and 92.2% of the Eu were selectively recovered at 295.9 °C, 67 min and a ratio of 1.27 gNH4Cl/gsolid, followed by quantitative selective leaching of the REE. Owed to its low chemicals consumption and operation costs, the current process allows for valorizing lamp waste even when raw material prices are low.

Superconductivity in SnO: a nonmagnetic analog to Fe-based superconductors?

We discovered that under pressure SnO with α-PbO structure, the same structure as in many Fe-based superconductors, e.g., ß-FeSe, undergoes a transition to a superconducting state for p≳6 GPa with a maximum Tc of 1.4 K at p=9.3 GPa. The pressure dependence of Tc reveals a domelike shape and superconductivity disappears for p≳16 GPa. It is further shown from band structure calculations that SnO under pressure exhibits a Fermi surface topology similar to that reported for some Fe-based superconductors and that the nesting between the hole and electron pockets correlates with the change of Tc as a function of pressure.

Scientists' warning on affluence.

For over half a century, worldwide growth in affluence has continuously increased resource use and pollutant emissions far more rapidly than these have been reduced through better technology. The affluent citizens of the world are responsible for most environmental impacts and are central to any future prospect of retreating to safer environmental conditions. We summarise the evidence and present possible solution approaches. Any transition towards sustainability can only be effective if far-reaching lifestyle changes complement technological advancements. However, existing societies, economies and cultures incite consumption expansion and the structural imperative for growth in competitive market economies inhibits necessary societal change.

Comparison of risk factors predicting return to work between patients with subacute and chronic non-specific low back pain: systematic review.

The objective of the study was to provide an inventory of predictive instruments and their constituting parameters associated with return to work in patients with subacute (2-10 weeks pain duration) and chronic (10-24 weeks pain duration) non-specific low back pain (NSLBP). Data sources included systematic review in Medline, Embase, Cinahl, Central, PEDro, Psyndex, PsychInfo/PsycLit, and Sociofile up to September 2008, in reference lists of systematic reviews on risk factors, and of included studies. For the systematic review, two reviewers independently assessed study eligibility and quality, and extracted data. Disagreements were resolved by consensus. Risk factors were inventorised and grouped into a somatic and psychosocial domain. 23 studies reporting on subacute and 16 studies reporting on chronic patients were included. The studies on subacute patients reported on a total of 56 biomedical factors out of which 35 (63%) were modifiable and 61 psychosocial factors out of which 51 (84%) were modifiable. The corresponding values in studies on chronic patients were 44 biomedical [27 (62%) modifiable] and 61 [40 (66%) modifiable] respectively. Our data suggest that the interdisciplinary approach in patients at risk to develop persistent NSLBP is justified in both, the subacute and chronic disease stages. Psychosocial interventions might be more effective in subacute stages since a higher proportion of modifiable risk factors were identified in that group.

University men's ice hockey: rates and risk of injuries over 6-years.

AIM: The aim of this study was to determine the injury rates of a Men's Varsity Ice Hockey team over six-years. Data on ice hockey injury rates and profile continue to increase in the hope of assisting with injury prevention. METHODS: The University of British Columbia Men's Varsity team has been followed prospectively over a six-year period. All student-athletes completed a preseason medical examinations and physiological assessments. The team physician evaluated each injury and the team therapist completed the injury report forms and the attendance records for each player. RESULTS: A total of 46215 player exposures were recorded. The combined injury rate was 3.70 injuries/1000 player game and practice exposures. A statistically significantly higher risk of injury was observed during games and the greatest risk of injury was observed during the second period. Forwards sustained greater percentage of injuries compared to defensemen and goalies. Sprains and strains accounted for 40% of all injuries, followed by concussions (13%). Non-contact injuries were most common, while the anatomy sustaining the most injuries was the head/neck/face region. A high percentage of the recorded injuries required less than seven days to return to full activity. CONCLUSIONS: The risk of injury for university ice hockey players is greater during games and is dependant on playing position. Players are prone to sprains and strains, which may not involve any contact. Concussion and knee joint injury rates continue to cause concern.

[The pelvic subcutaneous cross-over internal fixator]. / Der subkutane ventrale Fixateur interne (SVFI) am Becken.

The pelvic subcutaneous cross-over internal fixator is a minimally invasive technique for the fixation of instable anterior pelvic ring fractures. A USS-II-VAS screw is anchored bilaterally in the supra-acetabular region of the os ileum by a mini-incision approach. An angled fixation rod is inserted subcutaneously and after successful closed reduction attached to the screws forming a locking internal fixation. In a retrospective study of the clinical and radiological outcomes of 19 patients after an average follow-up of 2.54 years, results were excellent and good in 31.6%, moderate in 63.2% and poor in 5.3%. Complications were one wound infection, one loosening of the VAS screw and seven temporary lesions of the lateral femoral cutaneous nerve. The main benefits are a simple surgical technique preventing damage to soft tissue, a low risk of neurovascular lesions and the avoidance of pin infections. Moreover patients with multiple trauma profit from a shorter time of surgery and greater comfort allowing a prone position. The new procedure combines the advantages of internal osteosynthesis and a minimally invasive technique, providing early mobilization under full-weight bearing for instable pelvic fractures.

An optimization model for the treatment of perfluorocarboxylic acids considering membrane preconcentration and BDD electrooxidation.

Treatment of persistent perfluorocarboxylic acids in water matrixes requires of strong oxidation conditions, as those achieved by boron doped diamond (BDD) electrooxidation (ELOX). However, large scale implementation of ELOX is still hindered by its high energy consumption and economical investment. In this work, we used process systems engineering tools to define the optimal integration of a membrane pre-concentration stage followed by the BDD electrolysis of the concentrate, to drastically reduce the costs of treatment of perfluorohexanoic acid (PFHxA, 100 mg L-1) in industrial waste streams. A multistage membrane cascade system using nanofiltration (NF90 and NF270 membranes) was considered to achieve more sophisticated PFHxA separations. The aim was to minimize the total costs by determining the optimal sizing of the two integrated processes (membrane area per stage and anode area) and the optimal process variables (pre-concentration operating time, electrolysis time, input and output concentrations). The non-linear programming model (NLP) was implemented in the General Algebraic Modelling System (GAMS). The results showed that for a 2-log PFHxA abatement (99% removal), the optimal two membrane stages using the NF90 membrane obtains a 75.8% (6.4 $ m-3) reduction of the total costs, compared to the ELOX alone scenario (26.5 $ m-3). The optimized anode area and the energy savings, that were 85.3% and 88.2% lower than in ELOX alone, were the major contributions to the costs reduction. Similar results were achieved for a 3-log and 4-log PFHxA abatement, pointing out the promising benefits of integrating electrochemical oxidation with membrane pre-concentration through proper optimization for its large-scale application to waters impacted by perfluorocarboxylic acids.

Resonant inelastic x-ray incarnation of Young's double-slit experiment.

Young's archetypal double-slit experiment forms the basis for modern diffraction techniques: The elastic scattering of waves yields an interference pattern that captures the real-space structure. Here, we report on an inelastic incarnation of Young's experiment and demonstrate that resonant inelastic x-ray scattering (RIXS) measures interference patterns, which reveal the symmetry and character of electronic excited states in the same way as elastic scattering does for the ground state. A prototypical example is provided by the quasi-molecular electronic structure of insulating Ba3CeIr2O9 with structural Ir dimers and strong spin-orbit coupling. The double "slits" in this resonant experiment are the highly localized core levels of the two Ir atoms within a dimer. The clear double-slit-type sinusoidal interference patterns that we observe allow us to characterize the electronic excitations, demonstrating the power of RIXS interferometry to unravel the electronic structure of solids containing, e.g., dimers, trimers, ladders, or other superstructures.

Immunization with a cocktail of antigens fused with OprI reduces Neospora caninum vertical transmission and postnatal mortality in mice.

OprI is an outer membrane lipoprotein from Pseudomonas aeruginosa, and when fused to a recombinant antigen, will exert adjuvant properties by engaging Toll-like receptor 2, leading to dendritic cell activation. Previous studies have shown that the Neospora caninum (Nc) antigens NcPDI, NcROP2 and NcROP40 are implicated in host cell interactions and are promising vaccine candidates. In two independent experiments, the efficacy of a polyvalent vaccine formulation composed of OprI-NcPDI, OprI-NcROP2 and OprI-NcROP40 (collectively named O-Ags) was assessed in non-pregnant and pregnant Balb/c mouse models challenged with tachyzoites of the high-virulence isolate Nc-Spain7. Parameters that were investigated were clinical signs, fertility, parasite burden in adult mice, humoral and cellular immune responses at different time-points prior to and after challenge infection, vertical transmission and post-natal survival of offspring mice, all to explore potential correlations with efficacy. Vaccination of mice with O-Ags induced a mixed Th1/Th2 immune response in adult mice and led to significantly increased protection against cerebral infection. Vaccination with O-Ags also resulted in reduced vertical transmission, and postnatal disease in offspring was significantly inhibited at a rate not observed in mice infected with a high-virulence isolate to date. However, O-Ags mixed with TLR ligands targeting TLR3 and TLR7, which are known to induce clear Th1-biased responses, or vaccination with OprI fused to the non-N. caninum antigen ovalbumin (OprI-OVA) did not confer protection.