Abstract
The van-der-Waals material CrSBr stands out as a promising two-dimensional magnet. Here, we report on its detailed magnetic and structural characteristics. We evidence that it undergoes a ...transition to an A-type antiferromagnetic state below
T
N
≈ 140 K with a pronounced two-dimensional character, preceded by ferromagnetic correlations within the monolayers. Furthermore, we unravel the low-temperature hidden-order within the long-range magnetically-ordered state. We find that it is associated to a slowing down of the magnetic fluctuations, accompanied by a continuous reorientation of the internal field. These take place upon cooling below
T
s
≈ 100 K, until a spin freezing process occurs at
T
* ≈ 40 K. We argue this complex behavior to reflect a crossover driven by the in-plane uniaxial anisotropy, which is ultimately caused by its mixed-anion character. Our findings reinforce CrSBr as an important candidate for devices in the emergent field of two-dimensional magnetic materials.
Through the application of synthesis via molten indium flux, we have been able to expand the ternary Sc−Mn−Si system and the quaternary Sc−Mn−Al−Si system. Specifically, we report on five previously ...unknown chemical compounds, namely β‐ScMnSi2, Sc4+xMn4Si7–2x, Sc2Mn4Si5, Sc2Mn3Si4, and Sc4Mn2AlSi4. The compounds with the stoichiometries Sc2Mn4Si5, Sc2Mn3Si4, and Sc4Mn2AlSi4 have previously not been reported. We find that these crystallize in the V6Si5, Hf2Ru3Si4, and Ho4Ni2InGe4 structure types, respectively. For the ternary compounds with the stoichiometries of ScMnSi2 and Sc4+xMn4Si7–2x, we find clearly deviating structural solutions compared to earlier reports. β‐ScMnSi2 is found to crystallize in the monoclinic crystal system isostructural to a supercell of the MnTiSi2 structure and clearly deviating from the known orthorhombic α‐polymorph. The compound Sc4+xMn4Si7–2x is structurally very similar to Sc4Mn4Si7, but exhibits the P4/nmm space group instead of I4/mmm, and is related to the Zr4Co4Ge7 structure. Disorder between Si and Sc sites leads to the off‐stoichiometric composition, for which we found x=0.287(5).
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The DNA-PK complex is the major component of the predominant mechanism of DSB repair in humans. In addition, this complex is involved in many other processes such as DNA ...recombination, genome maintenance, apoptosis and transcription regulation. Several studies have linked the decrease of the DNA-PK activity with cancer initiation, due to defects in the repair. On another hand, higher DNA-PK expression and activity have been observed in various other tumor cells and have been linked with a decrease of the efficiency of anti-tumor drugs. It has also been shown that DNA-PK is critical for the integration of the HIV-1 DNA into the cell host genome and promotes replication and transcription of the virus.
Targeting this complex makes therefore sense to treat these two pathologies. However, according to the status of HIV-1 replication (active versus latent replication) or to the tumor grade cells (initiation versus metastasis), the way to target this DNA-PK complex might be rather different. In this review, we discuss the importance of DNA-PK complex in two major pathologies i.e. HIV-1 infection and cancer, and the rationale use of therapies aiming to target this complex.
Carbon fiber reinforced composites (CFRP) were activated by atmospheric pressure plasma source to improve the performance of galvanically plated Cu layer on its surface. Plasma activation was done by ...use of diffuse coplanar surface barrier discharge. Owing to its fabric structure, the morphology and chemical composition of CFRP structure is inherently heterogeneous. Therefore, the attention has been paid to mutual comparison of plasma induced chemical changes and the actual performance of metalized layers at morphologically distinct areas of CFRP surface. To evaluate these performances the XPS, FTIR, determination of surface free energy, nanoindentation, SEM and scratch tests were employed. The chemical analysis confirmed that the positive effect of plasma pre-treatment can be attributed to the introduction of the polar oxygen containing groups: -C=O and -O-C=O into the thin topmost epoxy resin areas, and –C-OH into thick inter-yarn epoxy resin areas. The results also showed that optimized plasma activation can mitigate the adhesion differences between the distinct surface structures.
•Woven topology of embedded carbon fibers interferes with plasma treatment.•Several minutes of atmospheric plasma treatment is needed to achieve good adhesion of Cu.•Nanoindentation showed uniform plating adhesion for longer plasma treatment.
The upper critical
field is a fundamental measure of the strength
of superconductivity in a material. It is also a cornerstone for the
realization of superconducting magnet applications. The critical ...field
arises because of the Cooper pair breaking at a limiting field, which
is due to the Pauli paramagnetism of the electrons. The maximal possible
magnetic field strength for this effect is
commonly known as the Pauli paramagnetic limit given as μ
0
H
Pauli
≈ 1.86T/K·
T
c
for a weak-coupling Bardeen–Schrieffer–Cooper
(BCS) superconductor. The violation of this limit is only rarely observed.
Exceptions include some low-temperature heavy Fermion and some strongly
anisotropic superconductors. Here, we report on the superconductivity
at 9.75 K in the centrosymmetric, cubic η-carbide-type compound
Nb
4
Rh
2
C
1−δ
, with a normalized
specific heat jump of Δ
C
/γ
T
c
= 1.64. We find that this material has a remarkably
high upper critical field of μ
0
H
c2
(0) = 28.5 T, which is exceeding by far its weak-coupling
BCS Pauli paramagnetic limit of μ
0
H
Pauli
= 18.1 T. Determination of the origin and consequences
of this effect will represent a significant new direction in the study
of critical fields in superconductors.
Abstract
Two-dimensional (2D) triangular lattice antiferromagnets (2D-TLA) often manifest intriguing physical and technological properties, due to the strong interplay between lattice geometry and ...electronic properties. The recently synthesized 2-dimensional transition metal dichalcogenide LiCrTe
$$_2$$
2
, being a 2D-TLA, enriched the range of materials which can present such properties. In this work, muon spin rotation (
$$\mu ^+$$
μ
+
SR) and neutron powder diffraction (NPD) have been utilized to reveal the true magnetic nature and ground state of LiCrTe
$$_2$$
2
. From high-resolution NPD the magnetic spin order at base-temperature is not, as previously suggested, helical, but rather collinear antiferromagnetic (AFM) with ferromagnetic (FM) spin coupling within the
ab
-plane and AFM coupling along the
c
-axis. The value if the ordered magnetic Cr moment is established as
$$\mu _{\textrm{Cr}}= 2.36~\mu _{\textrm{B}}$$
μ
Cr
=
2.36
μ
B
. From detailed
$$\mu ^+$$
μ
+
SR measurements we observe an AFM ordering temperature
$$T_{\textrm{N}}\approx 125$$
T
N
≈
125
K. This value is remarkably higher than the one previously reported by magnetic bulk measurements. From
$$\mu ^+$$
μ
+
SR we are able to extract the magnetic order parameter, whose critical exponent allows us to categorize LiCrTe
$$_2$$
2
in the 3D Heisenberg AFM universality class. Finally, by combining our magnetic studies with high-resolution synchrotron X-ray diffraction (XRD), we find a clear coupling between the nuclear and magnetic spin lattices. This suggests the possibility for a strong magnon–phonon coupling, similar to what has been previously observed in the closely related compound LiCrO
$$_2$$
2
.
We describe the previously unreported oxygen excess hexagonal antimony tungsten bronze with composition Sb0.5W3O10, in the following denoted as h‐SbxWO3+2x with x=0.167, to demonstrate its analogy to ...classical AxWO3 tungsten bronzes. This compound forms in a relatively narrow temperature range between 580 °C<T<620 °C. It was obtained as a dark‐blue polycrystalline powder, and as thin, needle‐shaped, blue single crystals. h‐SbxWO3+2x crystallizes in the hexagonal space group P6/mmm with the cell parameters a=7.4369(4) Å and c=3.7800(2) Å. The antimony and excess oxygen occupy the hexagonal channels within the network of corner‐sharing WO6 octahedra. h‐SbxWO3+2x has a resistivity of ρ300 K≈1.28 mΩ cm at room temperature, with little if any temperature‐dependence on cooling. DFT calculations on a simplified model for this compound find a metallic‐like electronic structure with the Fermi level falling within rather flat bands, especially around the Γ point.
Tungsten bronzes are a class of insertion compounds consisting of a network of corner‐sharing WO6 octahedra. There has been a logical deficiency in the structural chemistry of antimony tungsten bronzes, which is now bridged with the here reported discovery of a hexagonal tungsten bronze h‐SbxWO3+2x with x=0.167. This blue, metallic bronze consists of SbO2+ chains along the hexagonal channels.
Wastewater-based epidemiology is experiencing exponential development. Despite undeniable advantages compared to patient-centered approaches (cost, anonymity, survey of large populations without ...bias, detection of asymptomatic infected peoples…), major technical limitations persist. Among them is the low sensitivity of the current methods used for quantifying and sequencing viral genomes from wastewater. In situations of low viral circulation, during initial stages of viral emergences, or in areas experiencing heavy rains, the extremely low concentrations of viruses in wastewater may fall below the limit of detection of the current methods. The availability during crisis and the cost of the commercial kits, as well as the requirement of expensive materials such as high-speed centrifuge, can also present major blocks to the development of wastewater-based epidemiological survey, specifically in low-income countries. Thereby, highly sensitive, low cost and standardized methods are still needed, to increase the predictability of the viral emergences, to survey low-circulating viruses and to make the results from different labs comparable. Here, we outline and characterize new protocols for concentrating and quantifying SARS-CoV-2 from large volumes (500 mL-1 L) of untreated wastewater. In addition, we report that the methods are applicable for monitoring and sequencing. Our nucleic acid extraction technique (the routine C: 5 mL method) does not require sophisticated equipment such as automatons and is not reliant on commercial kits, making it readily available to a broader range of laboratories for routine epidemiological survey. Furthermore, we demonstrate the efficiency, the repeatability, and the high sensitivity of a new membrane-based concentration method (MBC: 500 mL method) for enveloped (SARS-CoV-2) and non-enveloped (F-specific RNA phages of genogroup II / FRNAPH GGII) viruses. We show that the MBC method allows the quantification and the monitoring of viruses in wastewater with a significantly improved sensitivity compared to the routine C method. In contexts of low viral circulation, we report quantifications of SARS-CoV-2 in wastewater at concentrations as low as 40 genome copies per liter. In highly diluted samples collected in wastewater treatment plants of French Guiana, we confirmed the accuracy of the MBC method compared to the estimations done with the routine C method. Finally, we demonstrate that both the routine C method processing 5 mL and the MBC method processing 500 mL of untreated wastewater are both compatible with SARS-CoV-2 sequencing. We show that the quality of the sequence is correlated with the concentration of the extracted viral genome. Of note, the quality of the sequences obtained with some MBC processed wastewater was improved by dilutions or enzyme substitutions suggesting the presence of specific enzyme inhibitors in some wastewater. To the best of our knowledge, our MBC method is one of the first efficient, sensitive, and repeatable method characterized for SARS-CoV-2 quantification and sequencing from large volumes of wastewater.
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