Ferroelasticity, anelasticity and magnetoelastic relaxation in Co-doped iron pnictide: Ba(Fe0.957Co0.043)2As2

The hypothesis that strain has a permeating influence on ferroelastic, magnetic and superconducting transitions in 122 iron pnictides has been tested by investigating variations of the elastic and anelastic properties of a single crystal of Ba(Fe_0.957Co_0.043)₂As₂ by resonant ultrasound spectroscopy as a function of temperature and externally applied magnetic field. Non-linear softening and stiffening of C ₆₆ in the stability fields of both the tetragonal and orthorhombic structures has been found to conform quantitatively to the Landau expansion for a pseudoproper ferroelastic transition which is second order in character. The only exception is that the transition occurs at a temperature (T _S  ≈  69 K) ~10 K above the temperature at which C ₆₆ would extrapolate to zero ([Formula: see text]  ≈  59 K). An absence of anomalies associated with antiferromagnetic ordering below T _N  ≈  60 K implies that coupling of the magnetic order parameter with shear strain is weak. It is concluded that linear-quadratic coupling between the structural/electronic and antiferromagnetic order parameters is suppressed due to the effects of local heterogeneous strain fields arising from the substitution of Fe by Co. An acoustic loss peak at ~50-55 K is attributed to the influence of mobile ferroelastic twin walls that become pinned by a thermally activated process involving polaronic defects. Softening of C ₆₆ by up to ~6% below the normal-superconducting transition at T _c  ≈  13 K demonstrates an effective coupling of the shear strain with the order parameter for the superconducting transition which arises indirectly as a consequence of unfavourable coupling of the superconducting order parameter with the ferroelastic order parameter. Ba(Fe_0.957Co_0.043)₂As₂ is representative of 122 pnictides as forming a class of multiferroic superconductors in which elastic strain relaxations underpin almost all aspects of coupling between the structural, magnetic and superconducting order parameters and of dynamic properties of the transformation microstructures they contain.

Strain relaxation behaviour of vortices in a multiferroic superconductor

The elastic and anelastic properties of a single crystal of Co-doped pnictide Ba(Fe_0.957Co_0.043)₂As₂ have been determined by resonant ultrasound spectroscopy in the frequency range 10-500 kHz, both as a function of temperature through the normal-superconducting transition (T _c  ≈  12.5 K) and as a function of applied magnetic field up to 12.5 T. Correlation with thermal expansion, electrical resistivity, heat capacity, DC and AC magnetic data from crystals taken from the same synthetic batch has revealed the permeating influence of strain on coupling between order parameters for the ferroelastic (Q _E) and superconducting (Q _SC) transitions and on the freezing/relaxation behaviour of vortices. Elastic softening through T _c in zero field can be understood in terms of classical coupling of the order parameter with the shear strain e ₆, λe ₆ [Formula: see text], which means that there must be a common strain mechanism for coupling of the form λ [Formula: see text] Q _E. At fields of ~5 T and above, this softening is masked by Debye-like stiffening and acoustic loss processes due to vortex freezing. The first loss peak may be associated with the establishment of superconductivity on ferroelastic twin walls ahead of the matrix and the second is due to the vortex liquid-vortex glass transition. Strain contrast between vortex cores and the superconducting matrix will contribute significantly to interactions of vortices both with each other and with the underlying crystal structure. These interactions imply that iron-pnictides represent a class of multiferroic superconductors in which strain-mediated coupling occurs between the multiferroic properties (ferroelasticity, antiferromagnetism) and superconductivity.

Spectral Evidence for Emergent Order in Ba_{1-x}Na_{x}Fe_{2}As_{2}

We report an angle-resolved photoemission spectroscopy study of the iron-based superconductor family, Ba_{1-x}Na_{x}Fe_{2}As_{2}. This system harbors the recently discovered double-Q magnetic order appearing in a reentrant C_{4} phase deep within the underdoped regime of the phase diagram that is otherwise dominated by the coupled nematic phase and collinear antiferromagnetic order. From a detailed temperature-dependence study, we identify the electronic response to the nematic phase in an orbital-dependent band shift that strictly follows the rotational symmetry of the lattice and disappears when the system restores C_{4} symmetry in the low temperature phase. In addition, we report the observation of a distinct electronic reconstruction that cannot be explained by the known electronic orders in the system.

Similar long-term efficacy of dual therapy containing raltegravir and a boosted protease inhibitor versus standard triple therapies in pretreated HIV-1-infected patients in a retrospective, real-life cohort of 14 years

OBJECTIVES

Raltegravir is used in many antiretroviral combinations, but its use in treatment-experienced patients without knowledge of baseline resistance is discussed controversially as a number of comparative studies have shown a higher rate of virological failure. However, it has been used frequently for the management of treatment failure, as it was the first integrase inhibitor to become available, and thus offered new options for patients with multiple resistance. The strategic use of raltegravir in this setting is examined in this study.

METHODS

In order to examine the efficacy of raltegravir in second and later lines of antiretroviral combinations, data for 740 patients from three clinical cohorts were analysed with a focus on the combinations that were used. These were stratified into the combination of two nonnucleoside reverse transcriptase inhibitors and raltegravir (2NRTIs + RAL), the combination of a boosted protease inhibitor and raltegravir (bPI + RAL), and other raltegravir-containing combinations.

RESULTS

The overall rate of virological suppression to < 50 HIV-1 RNA copies/mL was 69.5%. Although the baseline rate of virological suppression was higher for 2NRTIs + RAL than for the other strata, the outcomes were similar for all three groups at weeks 24, 48, 72 and 96.

CONCLUSIONS

These data indicate that, in a real-life setting, raltegravir can be used with a high virological success rate in treatment-experienced patients, and that the different combinations analysed (2NRTIs + RAL, bPI + RAL and others) show comparable rates of virological suppression.

Staging Cancer: TNM Literature 1963—1982

The prognosis of a malignant tumour largely depends on the stage of the disease at the beginning of a specific therapy; statistics of therapy are comparable only if they show the distribution of the cases to the different stages of the disease. Aiming to improve the comparability of the data and findings acquired from the cancer patient, the UICC has, for more than 30 years, been endeavouring to develop uniform rules for acquiring the stage of the disease and the degree of spread with malignant tumours. For this purpose, UICC has developed the TNM system which makes it possible to state accurately and in a reproduceable form the stage of the primary tumour (T) and the regional lymphatic nodes (N) as well as the possible existence of metastases (M). The third edition of the TNM rules appeared in English in 1978, in the following years in numerous other languages. Today the TNM system represents the only basis for the documentation of the cancer stage which has been introduced worldwide. However, it is by no means »complete«; for some forms of cancer proposals for TNM classification are still outstanding (e.g., tumours of the pancreas, the central nervous system, the bones and the soft tissues). Moreover, malignant lymphomas cannot be classified according to the principles of TNM. Here the so-called »Ann Arbor Classification« from the year 1971 is recommended.

The UICC has called upon its national committees to check the classification proposals available so far as to their usefulness and practicability. Corresponding field studies are under way in several countries. This bibliography covers a section of the TNM literature of the last 20 years. From a total number of about 2,000 publications, applying the TNM system, we selected 300 which discuss the system critically and, in most instances, make suggestions for its improvement. The first part of the bibliography contains an alphabetically arranged list of the titles according to authors’ names; the second part differentiates the tumors dealt with by their site.

We thank Mrs. L. Blumenthal, Mrs. I. Schäfer and Mrs. U. Wolber for their cooperation in setting up this bibliography.

Public antibodies to malaria antigens generated by two LAIR1 insertion modalities

We previously described two donors in whom the extracellular domain of LAIR1, a collagen-binding inhibitory receptor encoded on chromosome 191, was inserted between the V and the DJ segments of an antibody. This insertion generated, through somatic mutations, broadly reactive antibodies against RIFINs, a type of variant antigen expressed on the surface of Plasmodium falciparum-infected erythrocytes (IEs)2. To investigate how frequently such antibodies are produced in response to malaria infection, we screened plasma from two large cohorts of individuals living in malaria-endemic regions. We report that 5-10% of malaria-exposed individuals, but none of the European blood donors tested, have high levels of LAIR1-containing antibodies that dominate the response to IEs without conferring enhanced protection against febrile malaria. By analyzing the antibody-producing B cell clones at the protein, cDNA and gDNA level, we characterized additional LAIR1 insertions between the V and DJ segments and discovered a second insertion modality whereby the LAIR1 exon encoding the extracellular domain and flanking intronic sequences are inserted into the switch region. By exon shuffling, this mechanism leads to the production of bispecific antibodies in which the LAIR1 domain is precisely positioned at the elbow between the VH and CH1 domains. Additionally, in one donor the gDNA encoding the VH and CH1 domains was deleted, leading to the production of a camel-like LAIR1-containing antibody. Sequencing of the switch regions of memory B cells from European blood donors revealed frequent templated inserts originating from transcribed genes that, in rare cases, comprised exons with orientation and frame compatible with expression. Collectively, these results reveal different modalities of LAIR1 insertion that lead to public and dominant antibodies against IEs and suggest that insertion of templated DNA represents an additional mechanism of antibody diversification that can be selected in the immune response against pathogens and exploited for B cell engineering.

L-Arginine Modulates T Cell Metabolism and Enhances Survival and Anti-tumor Activity

Metabolic activity is intimately linked to T cell fate and function. Using high-resolution mass spectrometry, we generated dynamic metabolome and proteome profiles of human primary naive T cells following activation. We discovered critical changes in the arginine metabolism that led to a drop in intracellular L-arginine concentration. Elevating L-arginine levels induced global metabolic changes including a shift from glycolysis to oxidative phosphorylation in activated T cells and promoted the generation of central memory-like cells endowed with higher survival capacity and, in a mouse model, anti-tumor activity. Proteome-wide probing of structural alterations, validated by the analysis of knockout T cell clones, identified three transcriptional regulators (BAZ1B, PSIP1, and TSN) that sensed L-arginine levels and promoted T cell survival. Thus, intracellular L-arginine concentrations directly impact the metabolic fitness and survival capacity of T cells that are crucial for anti-tumor responses.

Adapting SimpleTreat for simulating behaviour of chemical substances during industrial sewage treatment

The multimedia model SimpleTreat, evaluates the distribution and elimination of chemicals by municipal sewage treatment plants (STP). It is applied in the framework of REACH (Registration, Evaluation, Authorization and Restriction of Chemicals). This article describes an adaptation of this model for application to industrial sewage treatment plants (I-STP). The intended use of this re-parametrized model is focused on risk assessment during manufacture and subsequent uses of chemicals, also in the framework of REACH. The results of an inquiry on the operational characteristics of industrial sewage treatment installations were used to re-parameterize the model. It appeared that one property of industrial sewage, i.e. Biological Oxygen Demand (BOD) in combination with one parameter of the activated sludge process, the hydraulic retention time (HRT) is satisfactory to define treatment of industrial wastewater by means of the activated sludge process. The adapted model was compared to the original municipal version, SimpleTreat 4.0, by means of a sensitivity analysis. The consistency of the model output was assessed by computing the emission to water from an I-STP of a set of fictitious chemicals. This set of chemicals exhibit a range of physico-chemical and biodegradability properties occurring in industrial wastewater. Predicted removal rates of a chemical from raw sewage are higher in industrial than in municipal STPs. The latter have typically shorter hydraulic retention times with diminished opportunity for elimination of the chemical due to volatilization and biodegradation.

Thermal Conductivity of the Iron-Based Superconductor FeSe: Nodeless Gap with a Strong Two-Band Character

The thermal conductivity κ of the iron-based superconductor FeSe was measured at temperatures down to 75 mK in magnetic fields up to 17 T. In a zero magnetic field, the electronic residual linear term in the T=0  K limit, κ_{0}/T, is vanishingly small. The application of a magnetic field B causes an exponential increase in κ_{0}/T initially. Those two observations show that there are no zero-energy quasiparticles that carry heat and therefore no nodes in the superconducting gap of FeSe. The full field dependence of κ_{0}/T has the classic two-step shape of a two-band superconductor: a first rise at very low field, with a characteristic field B^{⋆}≪B_{c2}, and then a second rise up to the upper critical field B_{c2}. This shows that the superconducting gap is very small (but finite) on one of the pockets in the Fermi surface of FeSe. We estimate that the minimum value of the gap, Δ_{min}, is an order of magnitude smaller than the maximum value, Δ_{max}.

Ultrafast structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2

Using femtosecond time-resolved hard x-ray diffraction, we investigate the structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2. The orthorhombic distortion analyzed by the transient splitting of the (1 0 3) Bragg reflection is suppressed on an initial timescale of 35 ps, which is much slower than the suppression of magnetic and nematic order. This observation demonstrates a transient state with persistent structural distortion and suppressed magnetic/nematic order which are strongly linked in thermal equilibrium. We suggest a way of quantifying the coupling between structural and nematic degrees of freedom based on the dynamics of the respective order parameters.

Pathogen-reduced Ebola virus convalescent plasma: first steps towards standardization of manufacturing and quality control including assessment of Ebola-specific neutralizing antibodies

BACKGROUND

Ebola virus disease is a public health emergency of international concern, and enormous efforts are being made in the development of vaccines and therapies. Ebola virus convalescent plasma is a promising anti-infective treatment of Ebola virus disease. Therefore, we developed and implemented a pathogen-reduced Ebola virus convalescent plasma concept in accordance with national, European and global regulatory framework.

MATERIALS AND METHODS

Ebola virus convalescent plasma manufacture and distribution was managed by a collection centre, two medical centres and an expert group from the European Blood Alliance. Ebola virus convalescent plasma was collected twice with an interval of 61 days from a donor recovering from Ebola virus disease in Germany. After pathogen reduction, the plasma was analysed for Ebola virus-specific immunoglobulin G (IgG) antibodies and its Ebola virus neutralizing activity.

RESULTS

Convalescent plasma could be collected without adverse events. Anti-Ebola virus IgG titres and Ebola-specific neutralizing antibodies in convalescent plasma were only slightly reduced after pathogen reduction treatment with S59 amotosalen/UVA. A patient in Italy with Ebola virus disease was treated with convalescent plasma without apparent adverse effects.

DISCUSSION

As proof of principle, we describe a concept and practical implementation of pathogen-reduced Ebola virus convalescent plasma manufacture, quality control and its clinical application to an Ebola virus disease patient.

Efficacy of raltegravir-containing regimens in antiretroviral-naïve and -experienced individuals in routine clinical practice

Raltegravir is one of the standard antiretroviral therapy (ART) options in treatment-experienced and -naïve patients. However, efficacy data from clinical practice are scarce. Therefore, the efficacy of raltegravir-containing ART in clinical practice was investigated retrospectively. In all, 295 treatment-naïve and -experienced patients were analysed using two different cut-offs for virological failure (200 or 50 copies/ml). The response at week 24 and onwards was evaluated as a 'time to loss of virological response' analysis and estimated as a survival function. Additionally, dual therapy regimens (raltegravir plus boosted protease inhibitor) were compared to standard combinations in experienced patients performing a snapshot analysis at weeks 24 and 48, as well as a time to loss of virological response analysis. A total of 86.2% of the 64 treatment-naïve patients maintained virological suppression using a cut-off of 200 copies/ml (c/ml), while 67.7% maintained virological suppression with a 50 copies/ml cut-off from week 24 until the end of observation. Among the 231 treatment-experienced patients, 84.8% maintained virological suppression from week 24 onwards using a cut-off of 200 copies/ml; and 71.0% using 50 copies/ml, respectively. In the subgroup snapshot analysis at week 24, 98.3% (86.7% using a cut-off of 50 copies/ml) and at week 48, 93.3% (80.0%) of patients responded to dual therapy. Patients who were receiving a standard background therapy responded in 88.3% (81.3%) at week 24 and in 86.0% (80.7%) at week 48. Differences were not significant. This study shows again the overall long-term efficacy of raltegravir-based ART and furthermore gives reference for a comparable efficacy of dual and standard nucleos(t)ide reverse transcriptase inhibitor-backbone regimens in experienced patients on raltegravir over a period of 48 weeks in a real-life cohort where patients with severe comorbidities were included.

Superconductivity-induced re-entrance of the orthorhombic distortion in Ba1-xKxFe2As2

Detailed knowledge of the phase diagram and the nature of the competing magnetic and superconducting phases is imperative for a deeper understanding of the physics of iron-based superconductivity. Magnetism in the iron-based superconductors is usually a stripe-type spin-density-wave, which breaks the tetragonal symmetry of the lattice, and is known to compete strongly with superconductivity. Recently, it was found that in some systems an additional spin-density-wave transition occurs, which restores this tetragonal symmetry, however, its interaction with superconductivity remains unclear. Here, using thermodynamic measurements on Ba_1−xK_xFe₂As₂ single crystals, we show that the spin-density-wave phase of tetragonal symmetry competes much stronger with superconductivity than the stripe-type spin-density-wave phase, which results in a novel re-entrance of the latter at or slightly below the superconducting transition.

The interplay between magnetic and superconducting phases is important to understand the physics of iron-based superconductivity. Here, the authors use thermodynamic measurements on Ba_1−xK_xFe₂As₂ single crystals to provide details of its phase diagram and the re-entrance of a C₂ spin-density-wave phase.

Direct characterization of photoinduced lattice dynamics in BaFe2As2

Ultrafast light pulses can modify electronic properties of quantum materials by perturbing the underlying, intertwined degrees of freedom. In particular, iron-based superconductors exhibit a strong coupling among electronic nematic fluctuations, spins and the lattice, serving as a playground for ultrafast manipulation. Here we use time-resolved X-ray scattering to measure the lattice dynamics of photoexcited BaFe₂As₂. On optical excitation, no signature of an ultrafast change of the crystal symmetry is observed, but the lattice oscillates rapidly in time due to the coherent excitation of an A_1g mode that modulates the Fe–As–Fe bond angle. We directly quantify the coherent lattice dynamics and show that even a small photoinduced lattice distortion can induce notable changes in the electronic and magnetic properties. Our analysis implies that transient structural modification can be an effective tool for manipulating the electronic properties of multi-orbital systems, where electronic instabilities are sensitive to the orbital character of bands.

In BaFe₂As₂, the lattice couples strongly to the magnetic and electronic degrees of freedom, providing a way to control them. Here, by means of time-resolved X-ray scattering, the authors measure rapid lattice oscillations, which can induce changes in the material's electronic and magnetic properties.