Role of alkaline metal in the rare-earth triangular antiferromagnet KYbO2_2

We report crystal structure and magnetic behavior of the triangular antiferromagnet KYbO$_2$, the A-site substituted version of the quantum spin liquid candidate NaYbO$_2$. The replacement of Na by K introduces an anisotropic tensile strain with 1.6% in-plane and 12.1% out-of-plane lattice expansion. Compared to NaYbO$_2$, both Curie-Weiss temperature and saturation field are reduced by about 20% as the result of the increased Yb--O--Yb angles, whereas the $g$-tensor of Yb$^{3+}$ becomes isotropic with $g=3.08(3)$. Field-dependent magnetization shows the plateau at 1/2 of the saturated value and suggests the formation of the up-up-up-down field-induced order in the triangular AYbO$_2$ oxides (A = alkali metal), in contrast to the isostructural selenides that exhibit the 1/3 plateau and the up-up-down field-induced order

Real-World Clinical Practice of Intensified Chemotherapies for Metastatic Pancreatic Cancer: Results from a Pan-European Questionnaire Study

Introduction: Recently, FOLFIRINOX and gemcitabine + nab-paclitaxel have been introduced as a novel intensified chemotherapy regimen for patients with metastasized pancreatic cancer. This study aims to analyze the real-world clinical practice with FOLFIRINOX and gemcitabine + nab-paclitaxel across Europe. Methods: Invitations to participate in an anonymous web-based questionnaire were sent via e-mail to 5,420 doctors in 19 European countries through the network of national gastroenterological, oncological, surgical and pancreatic societies as well as the European Pancreatic Club. The questionnaire consisted of 20 questions, 14 regarding the use of intensified chemotherapy, 4 regarding demographics of the participants, and 1 to verify the active involvement in the management of metastatic pancreatic cancer. Results: Two hundred and thirteen responses were received and 153 entries were valid for analysis. Of those, 63.4% came from an academic institution, 51% were oncologists, and 52% treated more than 25 cases per year. A majority of responses (71%) were from Italy (40%), Germany (23%), and Spain (8%). As first-line therapy, 11% used gemcitabine +/- erlotinib, 42% used FOLFIRINOX, and 47% used gemcitabine + nab-paclitaxel. Of the intensified regimens, both were applied to equal parts, but the likelihood of protocol deviation was higher when using FOLFIRINOX (p < 0.01). FOLFIRINOX was considered more toxic than gemcitabine + nab-paclitaxel (neutropenia 88 vs. 68%; polyneuropathy 42 vs. 41%; rapid deterioration 42 vs. 31%). FOLFIRINOX was rated to achieve longer survival with an acceptable quality of life (52 vs. 44%). Moreover, 57% of participants thought that gemcitabine + nab-paclitaxel should be the backbone for further clinical trials in pancreatic cancer. Conclusion: Intensified chemotherapy is widely used in pancreatic cancer patients in Europe following its recent clinical approval. Interestingly, nab-paclitaxel and FOLFIRINOX were used at comparable frequency although the latter had to be de-escalated more often

Temporal biomass dynamics of an Arctic plankton bloom in response to increasing levels of atmospheric carbon dioxide

Ocean acidification and carbonation, driven by anthropogenic emissions of carbon dioxide (CO2), have been shown to affect a variety of marine organisms and are likely to change ecosystem functioning. High latitudes, especially the Arctic, will be the first to encounter profound changes in carbonate chemistry speciation at a large scale, namely the under-saturation of surface waters with respect to aragonite, a calcium carbonate polymorph produced by several organisms in this region. During a CO2 perturbation study in Kongsfjorden on the west coast of Spitsbergen (Norway), in the framework of the EU-funded project EPOCA, the temporal dynamics of a plankton bloom was followed in nine mesocosms, manipulated for CO2 levels ranging initially from about 185 to 1420 μatm. Dissolved inorganic nutrients were added halfway through the experiment. Autotrophic biomass, as identified by chlorophyll a standing stocks (Chl a), peaked three times in all mesocosms. However, while absolute Chl a concentrations were similar in all mesocosms during the first phase of the experiment, higher autotrophic biomass was measured as high in comparison to low CO2 during the second phase, right after dissolved inorganic nutrient addition. This trend then reversed in the third phase. There were several statistically significant CO2 effects on a variety of parameters measured in certain phases, such as nutrient utilization, standing stocks of particulate organic matter, and phytoplankton species composition. Interestingly, CO2 effects developed slowly but steadily, becoming more and more statistically significant with time. The observed CO2-related shifts in nutrient flow into different phytoplankton groups (mainly dinoflagellates, prasinophytes and haptophytes) could have consequences for future organic matter flow to higher trophic levels and export production, with consequences for ecosystem productivity and atmospheric CO2.publishedVersio

From genotypes to organisms: State-of-the-art and perspectives of a cornerstone in evolutionary dynamics

Understanding how genotypes map onto phenotypes, fitness, and eventually organisms is arguably the next major missing piece in a fully predictive theory of evolution. We refer to this generally as the problem of the genotype-phenotype map. Though we are still far from achieving a complete picture of these relationships, our current understanding of simpler questions, such as the structure induced in the space of genotypes by sequences mapped to molecular structures, has revealed important facts that deeply affect the dynamical description of evolutionary processes. Empirical evidence supporting the fundamental relevance of features such as phenotypic bias is mounting as well, while the synthesis of conceptual and experimental progress leads to questioning current assumptions on the nature of evolutionary dynamics-cancer progression models or synthetic biology approaches being notable examples. This work delves into a critical and constructive attitude in our current knowledge of how genotypes map onto molecular phenotypes and organismal functions, and discusses theoretical and empirical avenues to broaden and improve this comprehension. As a final goal, this community should aim at deriving an updated picture of evolutionary processes soundly relying on the structural properties of genotype spaces, as revealed by modern techniques of molecular and functional analysis.Comment: 111 pages, 11 figures uses elsarticle latex clas

Magnetization and specific heat of the dimer system CuTe2O5

We report on magnetization and specific heat measurements on single-crystalline CuTe2O5. The experimental data are directly compared to theoretical results for two different spin structures, namely an alternating spin-chain and a two-dimensional (2D) coupled dimer model, obtained by Das et al. [Phys. Rev. B 77, 224437 (2008)]. While the analysis of the specific heat does not allow to distinguish between the two models, the magnetization data is in good agreement with the 2D coupled dimer model.Comment: 5 pages, 3 figure

Spin-state dependent pressure responsiveness of Fe(<scp>ii</scp>)-based triazolate metal–organic frameworks

Fe(II)-containing Metal–Organic Frameworks (MOFs) that exhibit temperature-induced spin-crossover (SCO) are candidate materials in the field of sensing, barocalorics, and data storage. Their responsiveness towards pressure is therefore of practical importance and is related to their longevity and processibility. The impact of Fe(II) spin-state on the pressure responsiveness of MOFs is yet unexplored. Here we report the synthesis of two new Fe(II)-based MOFs, i.e. Fe(cta)2 ((cta)− = 1,4,5,6-tetrahydrocyclopenta[d][1,2,3]triazolate) and Fe(mta)2 ((mta)− = methyl[1,2,3]triazolate), which are both in high-spin at room temperature. Together with the isostructural MOF Fe(ta)2 ((ta)− = [1,2,3]triazolate), which is in its low-spin state at room temperature, we apply these as model systems to show how spin-state controls their mechanical properties. As a proxy, we use their bulk modulus, which was obtained via high-pressure powder X-ray diffraction experiments. We find that an interplay of spin-state, steric effects, void fraction, and absence of available distortion modes dictates their pressure-induced structural distortions. Our results show for the first time the role of spin-state on the pressure-induced structural deformations in MOFs and bring us a step closer to estimating the effect of pressure as a stimulus on MOFs a priori

Suppression of Ru (S = 1) spin dimerization in La2RuO5 by Ti substitution

La2RuO5 shows a magneto-structural phase transition at 161 K with spin dimerization and concomitant formation of a non-magnetic singlet ground state. To gain a deeper insight into the origin of this transition systematic substitution of Ru by Ti has been carried out. Polycrystalline samples have been synthesized by thermal decomposition of citrate precursors leading to La2Ru(1-y)Ti(y)O5 (0 ≤ y ≤ 0.45). The crystal structure was investigated by x-ray powder diffraction at room temperature and at 100 K. The valences of Ti and Ru were obtained from x-ray absorption near edge structure spectroscopy at the Ti-K and the Ru-LIII absorption edges, respectively. The magnetic phase transition was investigated by magnetic susceptibility measurements as a function of Ti substitution, revealing a decreasing transition temperature on increasing the level of substitution. The step-like feature in the magnetic susceptibility reflecting the Ru-Ru spin dimerization transition becomes smeared out close to y = 0.3 and completely vanishes at y = 0.45, indicating complete suppression of spin-dimer formation. Additional specific-heat measurements show a continuous decrease of the magnetic entropy peak with increasing Ti substitution mirroring the reduced number of spin dimers due to the magnetic dilution. A magnetic anomaly of the dimerization transition can hardly be detected for y ≥ 0.3. Density functional theory calculations were carried out to study changes of the electronic band structure caused by the substitution. A possibly preferred distribution of Ti and Ru and the magnetic interactions as well as the change of the density of states close to the Fermi level are investigated. Based on these experimental results a detailed (y,T) phase diagram is proposed

Treatment of esophageal leakages with the Microtech-VAC-Stent: a monocentric early experience of three cases

Background: Endoscopic approaches in the treatment of transmural esophageal defects, either after esophageal resection or due to perforation, have demonstrated convincing feasibility. Surgical options are limited and associated with high morbidity and mortality rates. Currently, internal endoscopic drainage with pigtail stents, self-expanding metal stent (SEMS), or endoscopic vacuum therapy (EVT) are options for first-line treatment. Here, we report the outcome of the recently developed combination of SEMS and EVT using the endoscopic Microtech ® -VAC-Stent (EVS). Methods: Between June and July 2022, three consecutive patients (one female and two males) with esophageal transmural defects were treated with the Microtech ® -VAC-Stent. Two patients suffered from an anastomotic leak after oncologic gastroesophageal surgery, and one patient presented with esophageal perforation due to Boerhaave syndrome. Results: Three consecutive patients were successfully treated with EVS. In one patient, one EVS treatment was sufficient, whereas the other two patients needed two and six EVS exchanges. Exchanges were scheduled every 7 days and no procedural adverse events were observed. Conclusion: In line with the former case series, EVS therapy is a promising new approach for the treatment of esophageal leaks. Exchange of the EVS seems feasible every 7 days reducing interventions for the individual patient. Prospective studies comparing EVS with other endoscopic therapies are needed to define the best therapeutic approach

Structure, magnetic susceptibility, and specific heat of the spin-orbital-liquid candidate FeSc2S4: influence of Fe off-stoichiometry

We report structural, susceptibility and specific heat studies of stoichiometric and off-stoichiometric poly- and single crystals of the A-site spinel compound FeSc2S4. In stoichiometric samples no long-range magnetic order is found down to 1.8 K. The magnetic susceptibility of these samples is field independent in the temperature range 10 - 400 K and does not show irreversible effects at low temperatures. In contrast, the magnetic susceptibility of samples with iron excess shows substantial field dependence at high temperatures and manifests a pronounced magnetic irreversibility at low temperatures with a difference between ZFC and FC susceptibilities and a maximum at 10 K reminiscent of a magnetic transition. Single crystal x-ray diffraction of the stoichiometric samples revealed a single phase spinel structure without site inversion. In single crystalline samples with Fe excess besides the main spinel phase a second ordered single-crystal phase was detected with the diffraction pattern of a vacancy-ordered superstructure of iron sulfide, close to the 5C polytype Fe9S10. Specific heat studies reveal a broad anomaly, which evolves below 20 K in both stoichiometric and off-stoichiometric crystals. We show that the low-temperature specific heat can be well described by considering the low-lying spin-orbital electronic levels of Fe2+ ions. Our results demonstrate significant influence of excess Fe ions on intrinsic magnetic behavior of FeSc2S4 and provide support for the spin-orbital liquid scenario proposed in earlier studies for the stoichiometric compound.Comment: 36 pages, 19 figure