Ballistic magnon heat conduction and possible Poiseuille flow in the helimagnetic insulator Cu2_2OSeO3_3

We report on the observation of magnon thermal conductivity $\kappa_m\sim$ 70 W/mK near 5 K in the helimagnetic insulator Cu$_2$OSeO$_3$, exceeding that measured in any other ferromagnet by almost two orders of magnitude. Ballistic, boundary-limited transport for both magnons and phonons is established below 1 K, and Poiseuille flow of magnons is proposed to explain a magnon mean-free path substantially exceeding the specimen width for the least defective specimens in the range 2 K $<T<$ 10 K. These observations establish Cu$_2$OSeO$_3$ as a model system for studying long-wavelength magnon dynamics.Comment: 10pp, 9 figures, accepted PRB (Editor's Suggestion

Recycling-Oriented Design of the Al-Zn-Mg-Ca Alloys

Presented at the 1st International Electronic Conference on Metallurgy and Metals, 22 February–7 March 2021; Available online: https://iec2m.sciforum.net/.Approaches to the design of recycling-tolerant Al-Zn-Mg alloys were formulated to be achieved via combined Ca, Fe, and Si, and appropriate solidification conditions and heat treatment. A CalPhaD calculation and experimental study were employed for analysis of the Al-8%Zn-3%Mg alloy doped with 1–2%Ca, 0.5%Fe, and 0.5%Si. The Al-8%Zn-3%Mg-1%Ca-0.5%Fe-0.5%Si (AlZnMg1CaFeSi) alloy was preliminarily found to be promising since it showed a high equilibrium solidus, and an as-cast structure including curved phases (Al), Al3Fe, Al2CaSi2, Al10CaFe2, and (Al, Zn)4Ca; favouring a further spheroidization response during a two-step annealing at 450 °C, 3 h + 520 °C, 3 h. Furthermore, the alloy showed an excellent age-hardening response (195 HV, T6), which did not yield the values of the base alloy and outperformed the values of the other experimental counterparts. Regarding feasibility, 80% reduction hot rolling was successfully conducted, as well as a brief comparison with commercial 6063 impurity-tolerant alloys. As it showed qualitatively similar structural patterns and Fe and Si alloying opportunities, the AlZnMg1CaFeSi alloy may serve as a sustainable basis for the further development of high-strength aluminum alloys tailored for manufacture from scrap materials.Russian Science Foundation, Project No. 20-79-10373

Influence of severe plastic deformation on the structure and mechanical properties of eutectic Al-Zn-Mg-Fe-Ni alloy

The structure and phase evolution of the new eutectic high strength aluminium alloy Nikalin were investigated under high pressure torsion (HPT) by several numbers of the revolution of the anvil. The chemical composition of the investigated Nikalin alloy was as follows: Al (base)- 7.22Zn-2.95 Mg-0.52 Fe-0.57 Ni-0.2 Zr. (wt.%). The initial material was a coarse grained cast ingot after homogenization. It was established that the HPT process resulted in the deformation dissolution of the nanosized T-phase precipitates and the formation of a supersaturated aluminum solid solution simultaneously with the strong refinement of the structure to the grain-subgrain size of 130-150 nm. Due to that, the yield stress of the HPT alloy increased by a factor of 1.5, the ultimate tensile strength increased by a factor of 1.4, while preserving good ductility of 6-7%. The observed effect of the additional supersaturated solution upon HPT relative to the homogenized state appeared upon post-deformation annealing at 140 °C. An increase in the microhardness of the HPT alloy due to the MgZn2 phase precipitation was observed at 0.5- hours of annealing. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 18-03-00102Ministry of Science and Higher Education of the Russian Federation: АААА-А18-118020190116-6The research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (theme “Structura”, № АААА-А18-118020190116-6) supported in part by RFBR (project № 18-03-00102). The electron microscopy investigations were performed at the Center of Collaborative Access “Testing Center of Nanotechnologies and Advanced Materials” of the M.N. Mikheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences

Экспериментальное изучение единичных треков, полученных из смеси порошков Ti и Al при варьируемых параметрах процесса селективного лазерного плавления

The paper studies the effect of the laser scanning speed (vs) on the morphology of single tracks obtained from a mixture of Ti and Al powders in a stoichiometric ratio of 1 : 1 in longitudinal and cross sections. Droplets of splashed liquid were found on the outer surface of the track obtained at vs = 300 mm/s. Their appearance is resulted most likely from the release of gas bubbles formed due to the evaporation of aluminum having a lower melting point. A distortion of a single track along its length was observed with an increase in vs values up to 600 mm/s. It was found that tracks loose stability as the laser beam speed increases with «balls» formed on the track surface due to the significant Marangoni convection and the capillary liquid instability in the molten bath. An increase in the laser speed led to the appearance of pores mainly concentrated in the formed balls, and also influenced the track morphology in the cross section, namely, the width and height of the track, as well as the depth of substrate fusion. An increase in the scanning speed from 300 to 900 mm/s led virtually no substrate fusion, and the track width decreased from 194 to 136 μm, while its height increased almost 4 times – from 21 to 88 μm. X-ray microanalysis was conducted and element distribution maps were obtained to assess the structure of the tracks under study. It was found that the degree of liquid mixing in the molten bath is insufficient at scanning speeds of 300 and 600 mm/s, which leads to the segregation of elements over the track cross section. The central zone turns out to be enriched in aluminum, while titanium predominates at the base and is practically absent in the extreme zone (4.57 at.% Ti). X-ray microanalysis revealed the presence of unmelted titanium powder particles at vs = 900 mm/s. Presumably, it may be caused by insufficient laser power at such a high scanning speed.В ходе исследований изучено влияние скорости сканирования лазера (vс) на морфологию единичных треков, полученных из смеси порошков Ti и Al в стехиометрическом соотношении 1 : 1 в продольном и поперечном сечениях. На наружной поверхности трека, полученного при vс= 300 мм/с, были обнаружены капли выплеснувшейся жидкости, появление которых скорее всего было вызвано выбросом пузырьков газа, образовавшихся из-за испарения более легкоплавкого алюминия. С ростом значений vс до 600 мм/с наблюдалось искажение единичного трека по длине. Было установлено, что с увеличением скорости лазерного луча треки перестают быть стабильными, и из-за значительной конвекции Марангони и нестабильности капиллярной жидкости в расплавленной ванне по поверхности трека формируются «шарики». Повышение скорости лазера привело к появлению пор, которые в основном сконцентрированы в образовавшихся шариках, а также оказало влияние на морфологию трека в поперечном сечении, а именно – на ширину, высоту трека и глубину проплавления подложки. С увеличением скорости сканирования с 300 до 900 мм/с проплавления подложки практически не наблюдалось, ширина трека уменьшилась с 194 до 136 мкм, а его высота увеличилась почти в 4 раза – с 21 до 88 мкм. Для оценки структуры изучаемых треков был проведен микрорентгеноспектральный анализ (МРСА) и получены карты распределения элементов. Установлено, что при скоростях сканирования 300 и 600 мм/с перемешивание жидкости в ванне расплава происходит в недостаточной степени, что приводит к ликвации элементов по сечению треков. Центральная зона оказывается обогащеной алюминием, в то время как в основании преобладает титан, а в крайней зоне он практически отсутствует (4,57 ат.% Ti). При vс = 900 мм/с, по данным МРСА, наблюдалось наличие нерасплавившихся частиц порошка титана. Предположительной причиной этого может являться недостаточная мощность лазера при столь высокой скорости сканирования

SYNTHESIS AND PRODUCTION OF LAYERED CERAMIC MATERIALS BASED ON BARIUM STANNATE

Single-phase Ba2–xLaxSnO4+δ samples were obtained. Their decomposition after long storage in air is observed. High levels of p and n-type electronic conductivity were determined. The materials are suitable for technical applications without contact with ambient air

A Novel Laser-Based Zebrafish Model for Studying Traumatic Brain Injury and Its Molecular Targets

Traumatic brain injury (TBI) is a major public health problem. Here, we developed a novel model of non-invasive TBI induced by laser irradiation in the telencephalon of adult zebrafish (Danio rerio) and assessed their behavior and neuromorphology to validate the model and evaluate potential targets for neuroreparative treatment. Overall, TBI induced hypolocomotion and anxiety-like behavior in the novel tank test, strikingly recapitulating responses in mammalian TBI models, hence supporting the face validity of our model. NeuN-positive cell staining was markedly reduced one day, but not seven days, after TBI, suggesting increased neuronal damage immediately after the injury, and its fast recovery. The brain-derived neurotrophic factor (Bdnf) level in the brain dropped immediately after the trauma, but fully recovered seven days later. A marker of microglial activation, Iba1, was elevated in the TBI brain, albeit decreasing from Day 3. The levels of hypoxia-inducible factor 1-alpha (Hif1a) increased 30 min after the injury, and recovered by Day 7, further supporting the construct validity of the model. Collectively, these findings suggest that our model of laser-induced brain injury in zebrafish reproduces mild TBI and can be a useful tool for TBI research and preclinical neuroprotective drug screening. © 2022 by the authors.Saint Petersburg State University, SPbU: 73026081; Russian Science Foundation, RSF: 20-65-46006We thank Alisa S. Belova for technical support in experimental manipulations and cortisol assay. We also thank Anatoly A. Maslov for the idea of using laser radiation to introduce brain damage. A.V.K. lab is supported by St. Peterburg State University funds (Pure ID 73026081).This study was funded by Russian Science Foundation (grant No. 20-65-46006)

Induction of beta defensin 2 by NTHi requires TLR2 mediated MyD88 and IRAK-TRAF6-p38MAPK signaling pathway in human middle ear epithelial cells

<p>Abstract</p> <p>Background</p> <p>All mucosal epithelia, including those of the tubotympanium, are secreting a variety of antimicrobial innate immune molecules (AIIMs). In our previous study, we showed the bactericidal/bacteriostatic functions of AIIMs against various otitis media pathogens. Among the AIIMs, human β-defensin 2 is the most potent molecule and is inducible by exposure to inflammatory stimuli such as bacterial components or proinflammatory cytokines. Even though the β-defensin 2 is an important AIIM, the induction mechanism of this molecule has not been clearly established. We believe that this report is the first attempt to elucidate NTHi induced β-defensin expression in airway mucosa, which includes the middle ear.</p> <p>Methods</p> <p>Monoclonal antibody blocking method was employed in monitoring the TLR-dependent NTHi response. Two gene knock down methods – dominant negative (DN) plasmid and small interfering RNA (siRNA) – were employed to detect and confirm the involvement of several key genes in the signaling cascade resulting from the NTHi stimulated β-defensin 2 expression in human middle ear epithelial cell (HMEEC-1). The student's <it>t</it>-test was used for the statistical analysis of the data.</p> <p>Results</p> <p>The experimental results showed that the major NTHi-specific receptor in HMEEC-1 is the Toll-like receptor 2 (TLR2). Furthermore, recognition of NTHi component(s)/ligand(s) by TLR2, activated the Toll/IL-1 receptor (TIR)-MyD88-IRAK1-TRAF6-MKK3/6-p38 MAPK signal transduction pathway, ultimately leading to the induction of β-defensin 2.</p> <p>Conclusion</p> <p>This study found that the induction of β-defensin 2 is highest in whole cell lysate (WCL) preparations of NTHi, suggesting that the ligand(s) responsible for this up-regulation may be soluble macromolecule(s). We also found that this induction takes place through the TLR2 dependent MyD88-IRAK1-TRAF6-p38 MAPK pathway, with the primary response occurring within the first hour of stimulation. In combination with our previous studies showing that IL-1α-induced β-defensin 2 expression takes place through a MyD88-independent Raf-MEK1/2-ERK MAPK pathway, we found that both signaling cascades act synergistically to up-regulate β-defensin 2 levels. We propose that this confers an essential evolutionary advantage to the cells in coping with infections and may serve to amplify the innate immune response through paracrine signaling.</p

Geographical Distribution, Incidence, Malignancies, and Outcome of 136 Eastern Slavic Patients With Nijmegen Breakage Syndrome and NBN Founder Variant c.657_661del5

Nijmegen breakage syndrome (NBS) is a DNA repair disorder characterized by combined immunodeficiency and a high predisposition to lymphoid malignancies. The majority of NBS patients are identified with a homozygous five base pair deletion in the Nibrin (NBN) gene (c.657_661del5, p.K219fsX19) with a founder effect observed in Caucasian European populations, especially of Slavic origin. We present here an analysis of a cohort of 136 NBS patients of Eastern Slav origin across Belarus, Ukraine, Russia, and Latvia with a focus on understanding the geographic distribution, incidence of malignancy, and treatment outcomes of this cohort. Our analysis shows that Belarus had the highest prevalence of NBS (2.3 per 1,000,000), followed by Ukraine (1.3 per 1,000,000), and Russia (0.7 per 1,000,000). Of note, the highest concentration of NBS cases was observed in the western regions of Belarus and Ukraine, where NBS prevalence exceeds 20 cases per 1,000,000 people, suggesting the presence of an “Eastern Slavic NBS hot spot.” The median age at diagnosis of this cohort ranged from 4 to 5 years, and delay in diagnosis was more pervasive in smaller cities and rural regions. A total of 62 (45%) patients developed malignancies, more commonly in males than females (55.2 vs. 34.2%; p=0.017). In 27 patients, NBS was diagnosed following the onset of malignancies (mean age: 8 years). Malignancies were mostly of lymphoid origin and predominantly non-Hodgkin lymphoma (NHL) (n=42, 68%); 38% of patients had diffuse large B-cell lymphoma. The 20-year overall survival rate of patients with malignancy was 24%. However, females with cancer experienced poorer event-free survival rates than males (16.6% vs. 46.8%, p=0.036). Of 136 NBS patients, 13 underwent hematopoietic stem cell transplantation (HSCT) with an overall survival of 3.5 years following treatment (range: 1 to 14 years). Indications for HSCT included malignancy (n=7) and immunodeficiency (n=6). Overall, 9% of patients in this cohort reached adulthood. Adult survivors reported diminished quality of life with significant physical and cognitive impairments. Our study highlights the need to improve timely diagnosis and clinical management of NBS among Eastern Slavs. Genetic counseling and screening should be offered to individuals with a family history of NBS, especially in hot spot regions. © Copyright © 2021 Sharapova, Pashchenko, Bondarenko, Vakhlyarskaya, Prokofjeva, Fedorova, Savchak, Mareika, Valiev, Popa, Tuzankina, Vlasova, Sakovich, Polyakova, Rumiantseva, Naumchik, Kulyova, Aleshkevich, Golovataya, Minakovskaya, Belevtsev, Latysheva, Latysheva, Beznoshchenko, Akopyan, Makukh, Kozlova, Varabyou, Ballow, Ong, Walter, Kondratenko, Kostyuchenko and Aleinikova.We thank all doctors for clinical help for patients. We also appreciate the support of patient and their parents for agreeing to take part in this study. TP thanks Sergey?Nikulshin, Marika Grutupa, and Zanna Kovalova. We thank Joseph Dasso for editing this manuscript, primarily for proper English

Functional and Computational Analysis of Amino Acid Patterns Predictive of Type III Secretion System Substrates in Pseudomonas syringae

Bacterial type III secretion systems (T3SSs) deliver proteins called effectors into eukaryotic cells. Although N-terminal amino acid sequences are required for translocation, the mechanism of substrate recognition by the T3SS is unknown. Almost all actively deployed T3SS substrates in the plant pathogen Pseudomonas syringae pathovar tomato strain DC3000 possess characteristic patterns, including (i) greater than 10% serine within the first 50 amino acids, (ii) an aliphatic residue or proline at position 3 or 4, and (iii) a lack of acidic amino acids within the first 12 residues. Here, the functional significance of the P. syringae T3SS substrate compositional patterns was tested. A mutant AvrPto effector protein lacking all three patterns was secreted into culture and translocated into plant cells, suggesting that the compositional characteristics are not absolutely required for T3SS targeting and that other recognition mechanisms exist. To further analyze the unique properties of T3SS targeting signals, we developed a computational algorithm called TEREE (Type III Effector Relative Entropy Evaluation) that distinguishes DC3000 T3SS substrates from other proteins with a high sensitivity and specificity. Although TEREE did not efficiently identify T3SS substrates in Salmonella enterica, it was effective in another P. syringae strain and Ralstonia solanacearum. Thus, the TEREE algorithm may be a useful tool for identifying new effector genes in plant pathogens. The nature of T3SS targeting signals was additionally investigated by analyzing the N-terminus of FtsX, a putative membrane protein that was classified as a T3SS substrate by TEREE. Although the first 50 amino acids of FtsX were unable to target a reporter protein to the T3SS, an AvrPto protein substituted with the first 12 amino acids of FtsX was translocated into plant cells. These results show that the T3SS targeting signals are highly mutable and that secretion may be directed by multiple features of substrates