Search Results (45)

Neutron powder diffraction experiments were carried out to characterize mechanochemically synthesized (Fe₂O₃)_1−x(Al₂O₃)_x solid solutions with corundum-type structure, focusing on their lattice and magnetic structures with varying temperature and composition. The neutron diffraction experiments for (Fe₂O₃)_0.5(Al₂O₃)_0.5 in the temperature range between 4 K and 300 K reveal that no significant structural phase transition occurred. The behavior of temperature variation of lattice parameters is different from α-Fe₂O₃ and α-Al₂O₃ and reveals the thermal expansion coefficients of α_a = 5.76(2) × 10⁻⁶ K⁻¹ and α_c = 6.19(5) × 10⁻⁶ K⁻¹ between 200 K and 300 K. The room temperature neutron diffraction of (Fe₂O₃)_1−x(Al₂O₃)_x shows a linear decrease in lattice parameters with the aluminum substitution, following Vegard’s law, along with a decrease in the magnetic moment, indicating the dilution effect on spin interactions. With the increase in the aluminum substitution from x = 0 to 0.5, the deduced magnetic moment decreases from 2.224 μ_B to 0.862 μ_B. Full article

In this article, we study a fractional lower-order differential equation, $-D_{0+}^{\alpha }{\rm Y}\left(\xi \right)+\mathrm{a}\left(\xi \right){\rm Y}\left(\xi \right)=\mathrm{y}\left(\xi \right),\xi \in (0,1),\alpha \in (1,2),$ with a Dirichlet-type boundary condition, where $\mathrm{a}\left(\xi \right)\in L^1[0,1]$ permits singularity. When the coefficient of perturbation term $\mathrm{a}\left(\xi \right)$ is continuous on $[0,1]$, Graef et al. derived the associated Green’s function under certain conditions on $\mathrm{a}$, but failed to obtain its positivity. We obtain some positive properties of the Green’s function of this problem under certain conditions. The results will fill the gap in the above literature. As for application of the theoretical results, a singular fractional differential equation with a perturbation term is considered. The unique positive solution is obtained by using the fixed point theorem, and an iterative sequence is established to approximate it. In addition, a semipositone fractional differential equation, $-D_{0+}^{\alpha }{\rm Y}\left(\xi \right)=\mu \mathcal{F}(\xi ,{\rm Y}\left(\xi \right)),\xi \in (0,1),\alpha \in (1,2),$ is also considered. The existence of positive solutions is determined under a more general condition, $\mathcal{F}(\xi ,\mathrm{x})\ge -\mathrm{b}\left(\xi \right)\mathrm{x}-\mathrm{e}\left(\xi \right)$, where $\mathrm{b}\left(\xi \right),\mathrm{e}\left(\xi \right)\in L^1[0,1]$ are non-negative functions. Relevant examples are listed to manifest the theoretical results. Full article

Background/objectives: Ultraviolet-B (UVB) represents a major extrinsic factor in skin cancer development, causing cellular changes that are not yet fully understood. Aquaporins (AQPs) are a family of transmembrane proteins that favor water transport and are involved in several pathways. Nicotinamide (NAM), a vitamin B3 derivate, is a safe molecule able to reduce UVB-induced damages. This study aims to verify whether AQP expression is affected by UVB exposure at different dosages and times and to evaluate NAM’s effects against UVB-induced damages. Methods: A375 cells were exposed to 40, 100, and 200 mJ/cm² UVB doses and analyzed 0, 1, 18, and 24 h post-irradiation. Results: We found that the 40 mJ/cm² UVB dose, 24 h post-irradiation, caused the most detrimental effects an overall overexpression and dimerization of AQPs. However, in the presence of NAM 25 μM, the cell cycle was restored, leading to improved cell viability and proliferation, reduced ROS levels, and reduced DNA damage. Moreover, we found decreased AQPs expression and dimerization. Conclusions: Overall, NAM effectively mitigates UVB-induced cellular damage, including AQPs overexpression, and may serve as a protective agent against UVB-related skin damage. Full article

Aluminum (Al) toxicity is a major constraint to crop productivity in acidic soils, frequently encountered in banana-growing regions. This study investigates physiological and biochemical responses to Al stress in two Cavendish banana genotypes, Baodao and Baxi (Musa acuminata L.), which exhibit contrasting levels of Al tolerance. Banana plantlets were grown hydroponically under three AlCl₃ concentrations (0, 100, and 500 μM) for 24, 48, and 72 h. Root elongation was progressively inhibited with increasing Al concentrations, with Baodao showing greater inhibition than Baxi. Al primarily accumulated in roots and displayed genotype-specific distribution patterns: Baodao concentrated more Al in root tips, suggesting lower exclusion efficiency. In contrast, Baxi, the Al-tolerant genotype, translocated Al from roots to shoots more effectively, indicating potential sequestration mechanisms in less sensitive tissues. Al stress influenced enzyme activities, with Baxi exhibiting higher phosphoenolpyruvate carboxylase and citrate synthase activities at 100 µM Al, while both genotypes showed similar reductions at 500 µM. Baodao experienced more pronounced reductions in H⁺-ATPase activity. At 100 µM Al, Baxi retained higher levels of key nutrients (P, Zn, Mg, Mn, Fe, K, and B) in essential tissues than Baodao. However, nutrient levels were reduced in both genotypes at 500 µM Al. These findings highlight Baxi’s superior resilience under Al stress, making it a suitable genotype for cultivation and breeding in acidic soils. Full article

The CMS experiment at the LHC has advanced precision measurements of rare B-meson and charm decays, offering insights into phenomena beyond the Standard Model (SM). This paper highlights key results from Run 2 and Run 3 data, including the branching fraction and lifetime of $B_s\to {\mu }^{+}{\mu }^{-}$, angular analyses of $B^0\to K^{*0}{\mu }^{+}{\mu }^{-}$, the first observation of $J/\psi \to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$, and stringent limits on $D^0\to {\mu }^{+}{\mu }^{-}$. These findings provide tests of SM predictions while probing subtle hints of new physics. Full article

In this paper, we present a “non-linear” factorization of a family of non-normal operators arising from Gribov’s theory of the following form: ${\displaystyle H_{{\lambda }^{\prime },\mu ,\lambda }={\lambda }^{\prime }{A}^{{*}^2}{A}^2+\mu A^{*}A+i\lambda A^{*}}$$(A+A^{*})A,$ where the quartic Pomeron coupling ${\lambda }^{\prime }$, the Pomeron intercept $\mu$ and the triple Pomeron coupling $\lambda$ are real parameters, and $i^2=-1$. $A^{*}$ and A are, respectively, the usual creation and annihilation operators of the one-dimensional harmonic oscillator obeying the canonical commutation relation $[A,A^{*}]=I$. In Bargmann representation, we have ${\displaystyle A⟷\frac{d}{dz}}$ and ${\displaystyle A^{*}⟷z}$, $z=x+iy$. It follows that ${\displaystyle H_{{\lambda }^{\prime },\mu ,\lambda }}$ can be written in the following form: ${\displaystyle H_{{\lambda }^{\prime },\mu ,\lambda }=p\left(z\right)\frac{d^2}{d{z}^2}+q\left(z\right)\frac{d}{dz},}$ where $p\left(z\right)={\lambda }^{\prime }{z}^2+i\lambda z$ and $q\left(z\right)=i\lambda z^2+\mu z.$ This operator is an operator of the Heun type where the Heun operator is defined by $H=p\left(z\right){\displaystyle \frac{d^2}{d{z}^2}}+q\left(z\right){\displaystyle \frac{d}{dz}}+v\left(z\right),$ where $p\left(z\right)$ is a cubic complex polynomial, $q\left(z\right)$ and $v\left(z\right)$ are polynomials of degree at most 2 and 1, respectively, which are given. For $z=-iy$, $H_{{\lambda }^{\prime },\mu ,\lambda }$ takes the following form: $H_{{\lambda }^{\prime },\mu ,\lambda }=-a\left(y\right){\displaystyle \frac{d^2}{d{y}^2}}+b\left(y\right){\displaystyle \frac{d}{dz}},$ with $a\left(y\right)=y(\lambda -{\lambda }^{\prime }y)$ and ${\displaystyle b\left(y\right)=y(\lambda y+\mu ).}$ We introduce the change of variable $y={\displaystyle \frac{\lambda }{2{\lambda }^{\prime }}}(1-cos\left(\theta \right))$, $\theta \in [0,\pi ]$ to obtain the main result of transforming ${\displaystyle H_{{\lambda }^{\prime },\mu ,\lambda }}$ into a product of two first-order operators: ${\displaystyle {\tilde{H}}_{{\lambda }^{\prime },\mu ,\lambda }={\lambda }^{\prime }(\frac{d}{d\theta }+\alpha \left(\theta \right))(-\frac{d}{d\theta }+\alpha \left(\theta \right)),}$ with $\alpha \left(\theta \right)$ being explicitly determined. Full article

This paper is concerned with the following $L^2$-subcritical Kirchhoff-type equation $-\left(a+b{\left({\int }_{{\mathbb{R}}^2}{|\nabla u|}^{2}dx\right)}^s\right)\Delta u+V\left(x\right)u=\mu u+\beta {\left|u\right|}^{2}u,x\in {\mathbb{R}}^2$, with ${\int }_{{\mathbb{R}}^2}{\left|u\right|}^{2}dx=1$. We give a detailed analysis of the limit property of the $L^2$-normalized solution when exponent s tends toward 0 from the right (i.e., $s\searrow 0$). Our research extends previous works, in which the authors have displayed the limit behavior of $L^2$-normalized solutions when $s=1$ as $a\searrow 0$ or $b\searrow 0$. Full article

Infrared dark clouds (IRDCs) are fruitful objects to study the fragmentation of interstellar filaments and initial conditions and early stages of high-mass ($M>8$ M_⊙) star formation. We used the Yebes 40 m and Institut de Radioastronomie Millimétrique (IRAM) 30 m radio telescopes to carry out the first single-pointing spectral line observations towards the IRDC G1.75-0.08, which is a filamentary Central Molecular Zone (CMZ) cloud. Our aim is to reach an improved understanding of the gas kinematics and dynamical state of the cloud and its two clumps that we call clumps A and B. We also aim to determine the fractional abundances of the molecules detected at 3 mm towards G1.75-0.08. We detected HNCO$(J_{K_a,K_c}=4_{0,4}-3_{0,3})$, HCN$(J=1-0)$, and HCO⁺$(J=1-0)$ towards both clumps. The N₂H⁺$(J=1-0)$ line was detected only in clump B, while N₂D⁺$(J=1-0)$ was not detected at all. The HCN and HNCO spectra exhibit two velocity components. The abundances of the detected species are comparable to those in other IRDCs. An upper limit to the [N₂D⁺]/[N₂H⁺] deuterium fraction of <0.05 derived towards clump B is consistent with values observed in many high-mass clumps. The line mass analysis suggests that the G1.75-0.08 filament is subcritical by a factor of $11\pm 6$, and the clumps were found to be gravitationally unbound (${\alpha }_{\mathrm{vir}}>2$). Our finding that G1.75-0.08 is strongly subcritical is atypical compared to the general population of Galactic filamentary clouds. The cloud’s location in the CMZ might affect the cloud kinematics similar to what has been found for the Brick IRDC, and the cloud’s dynamical state might also be the result of the turbulent motions or shear and tidal forces in the CMZ. Because the target clumps are dark at 70 $\mathsf{\mu }$m and massive (several ${10}^3$ M_⊙), they can be considered candidates for being high-mass starless clumps but not prestellar because they are not gravitationally bound. Full article

The following semi-linear elliptic equations involving Hardy–Sobolev critical exponents $-\Delta u-\mu \frac{u}{{\left|x\right|}^2}=\frac{{\left|u\right|}^{2^{*}\left(s\right)-2}}{{\left|x\right|}^s}u+g(x,u),x\in \mathrm{\Omega }\setminus \left\{0\right\},u=0,x\in \partial \mathrm{\Omega }$ have been investigated, where $\mathrm{\Omega }$ is an open-bounded domain in ${\mathbb{R}}^N\left(N\ge 3\right)$, with a smooth boundary $\partial \mathrm{\Omega }$, $0\in \mathrm{\Omega },0\le \mu <\overline{\mu }:={\left(\frac{N-2}{2}\right)}^2,0\le s<2$, and $2^{*}\left(s\right)=2\left(N-s\right)/\left(N-2\right)$ is the Hardy–Sobolev critical exponent. This problem comes from the study of standing waves in the anisotropic Schrödinger equation; it is very important in the fields of hydrodynamics, glaciology, quantum field theory, and statistical mechanics. Under some deterministic conditions on $g$, by a detailed estimation of the extremum function and using mountain pass lemma with ${\left(PS\right)}_c$ conditions, we obtained that: (a) If $\mu \le \overline{\mu }-1$, and $\lambda <{\lambda }_1\left(\mu \right),$ then the above problem has at least a positive solution in $H_0^1\left(\mathrm{\Omega }\right)$; (b) If $\overline{\mu }-1<\mu <\overline{\mu }$, then when ${\lambda }_{*}\left(\mu \right)<\lambda <{\lambda }_1\left(\mu \right)$, the above problem has at least a positive solution in $H_0^1\left(\mathrm{\Omega }\right)$; (c) if $\overline{\mu }-1<\mu <\overline{\mu }$ and $\mathrm{\Omega }=B(0,R)$, then the above problem has no positive solution for $\lambda \le {\lambda }_{*}\left(\mu \right).$ These results are extensions of E. Jannelli’s research ($g(x,u)=\lambda u$). Full article

To enhance the specificity and sensitivity, cut the cost, and realize joint detection of multiple indicators, an immunoassay system based on the technology of time-resolved fluorescence resonance energy transfer (TR-FRET) was studied. Due to the FRET of the reagent, the donor probe and acceptor probe emitted specific fluorescence to enhance specificity. Long-lifetime specific fluorescence from the acceptor probe was combined with time-resolved technology to enhance sensitivity. A xenon flash lamp and a photomultiplier tube (PMT) were selected as the light source and detector, respectively. A filter-switching mechanism was placed in the light path, so the fluorescence signal from the donor and acceptor was measured alternately. The instrument’s design is given, and some specificI parts are described in detail. Key technical specifications of the instrument and procalcitonin (PCT), C-reactive protein (CRP), and interleukin-6(IL-6) were tested, and the test results were presented subsequently. The CV value of the self-designed counting module is better than 0.01%, and the instrument noises for 620 nm and 665 nm are 41.44 and 10.59, respectively. When set at 37 °C, the temperature bias (B) is 0.06 °C, and the temperature fluctuation is 0.10 °C. The CV and bias are between ±3% and 5%, respectively, when pipetting volumes are between 10 μL and 100 μL. Within the concentration range of 0.01 nM to 10 nM, the luminescence values exhibit linear regression correlation coefficients greater than 0.999. For PCT detection, when the concentration ranges from 0.02 ng/mL to 50 ng/mL, the correlation coefficient of linear fitting exceeds 0.999, and the limit of quantification is 0.096 ng/mL. For CRP and IL-6, the detection concentration ranges from 0 ng/mL to 500 ng/mL and 0 ng/mL to 20 ng/mL, respectively, with limits of quantification of 2.70 ng/mL and 2.82 ng/mL, respectively. The experimental results confirm the feasibility of the technical and instrumental solutions. Full article

This article reviews the most recent measurements of $B_{\left(s\right)}^0$ → μ⁺μ⁻ decay properties at the Large Hadron Collider (LHC) which are the most precise to date. The measurements of the branching fraction and effective lifetime of the $B_s^0$ → μ⁺μ⁻ decay by the ATLAS, CMS, and LHCb collaborations, as well as the search for $B^0$ → μ⁺μ⁻ decays, are summarized with a focus on the experimental challenges. Furthermore, prospects are given for these measurements and new observables that become accessible with the foreseen amounts of data by the end of the LHC. Full article

One electron oxidation of the monometallic alkenylacetylide complexes [Ru{C≡CC(R)=CH₂}(dppe)Cp*] (1) and [Ru{C≡CC(R)=CH₂}Cl(dppe)₂] (2) (R = Ph (a); R = 4-MeS-C₆H₄ (b)) generates in each case a dinuclear bis(allenylidene) complex [{Ru}₂{μ-C=C=C(R)–CH₂–H₂C–(R)C=C=C}][PF₆]₂ ({Ru} = Ru(dppe)Cp* ([3a,b][PF₆]₂); {Ru} = RuCl(dppe)₂ ([4a,b][PF₆]₂), containing an unsaturated ethane bridge between both allenylidene moieties. Deprotonation of this ethane bridge results in the formation of the previously reported octa-3,5-diene-1,7-diyndiyl-bridged bimetallic species [{Ru}₂{μ-C≡CC(R)=CH–HC=(R)CC≡C}] ({Ru} = Ru(dppe)Cp* (5a,b); {Ru} = RuCl(dppe)₂ (6a,b). The isolation of these complexes illustrates a general synthetic route to these conjugated bimetallic species from monomeric alkenylacetylide precursors. Electrochemical and spectroelectrochemical investigations evince the ready formation of the representative redox series [5a]ⁿ⁺, and TD-DFT calculations performed on optimised structures featuring the simplified {Ru(dmpe)Cp} coordination sphere [{Ru(dmpe)Cp}₂{μ-C≡CC(Ph)=HC–CH(Ph)CC≡C}]ⁿ⁺ ([5a^†]ⁿ⁺) (n = 0, 1, 2) reveal significant delocalisation of the unpaired charge in the formally mixed-valent species (n = 1), consistent with Class III assignment within the Robin–Day classification scheme. Full article

A fast feedback loop (FFL) based on comparators is proposed in this paper. The FFL improves the transient response characteristics of the output-capacitorless low-dropout (OCL-LDO) regulator. When the load current switches between 1 mA and 100 mA with 1 $\mathsf{\mu }$s edge time, the overshoot and undershoot are 33 mV and 37 mV, respectively, and recovery time is 1.2 $\mathsf{\mu }$s and 1.6 $\mathsf{\mu }$s, respectively. A damping-factor-control (DFC) frequency compensation circuit is used to ensure the stability of the OCL-LDO, and the simulation results show that the phase margin exceeds 50 degree in the entire load variation range. This design is based on 180 nm process, and the area of the chip is 0.068 mm${}^2$ (without pads). A band-gap reference circuit is also designed in this work; its output voltage is 1.2 V and its temperature coefficient is 7.96 ppm/${}^{\circ }$C. The input voltage range of the proposed OCL-LDO is 2.5 V to 5 V with a linear regulation rate of 0.128 mV/V and a load regulation rate of 0.0017 mV/mA. In addition, the load range of the proposed OCL-LDO is 0 mA to 100 mA, and the minimum required external capacitance is 0 F. The power supply rejection ratio (PSRR) is −46 dB @ 1 kHz. Full article

The influences of uniaxial tension strain in the x direction (ε_x) on the mechanical stability, stress–strain relations, elastic properties, hardness, ductility, and elastic anisotropy of Al₆Mg₁Zr₁ compound were studied by performing first-principle calculations on the basis of density functional theory. It was found that Al₆Mg₁Zr₁ compound is mechanically stable in the range of strain ε_x from 0 to 6%. As the strain ε_x increased from 0 to 6%, the stress in the x direction (σ_x) first grew linearly and then followed a nonlinear trend, while the stresses in the y and z directions (σ_y and σ_z) showed a linearly, increasing trend all the way. The bulk modulus B, shear modulus G, and Young’s modulus E all dropped as the strain ε_x increased from 0 to 6%. The Poisson ratio μ of Al₆Mg₁Zr₁ compound was nearly unchanged when the strain ε_x was less than 3%, but then it grew quickly. Vickers hardness H_V of Al₆Mg₁Zr₁ compound dropped gradually as the strain ε_x increased from 0 to 6%. The Al₆Mg₁Zr₁ compound was brittle when the ε_x was less than 4%, but it presented ductility when the strain ε_x was more than 4%. As the strain ε_x increased from 0 to 6%, the compression anisotropy percentage (A_B) grew and its slope became larger when the strain ε_x was more than 4%, while both the shear anisotropy percentage (A_G) and the universal anisotropy index (A_U) first dropped slowly and then grew quickly. These results demonstrate that imposing appropriate uniaxial tension strain can affect and regulate the mechanical properties of Al₆Mg₁Zr₁ compound. Full article

A series of iridium complexes with bis(diisopropylphenyl)iminoacenaphtene (dpp-bian) ligands, [Ir(cod)(dpp-bian)Cl] (1), [Ir(cod)(NO)(dpp-bian)](BF₄)₂ (2) and [Ir(cod)(dpp-bian)](BF₄) (3), were prepared and characterized by spectroscopic techniques, elemental analysis, X-ray diffraction analysis and cyclic voltammetry (CV). The structures of 1–3 feature a square planar backbone consisting of two C = C π-bonds of 1,5-cyclooctadiene (cod) and two nitrogen atoms of dpp-bian supplemented with a chloride ion (for 1) or a NO group (for 2) to complete a square-pyramidal geometry. In the nitrosyl complex 2, the Ir-N-O group has a bent geometry (the angle is 125°). The CV data for 1 and 3 show two reversible waves between 0 and -1.6 V (vs. Ag/AgCl). Reversible oxidation was also found at E_1/2 = 0.60 V for 1. Magnetochemical measurements for 2 in a range from 1.77 to 300 K revealed an increase in the magnetic moment with increasing temperature up to 1.2 μ_B (at 300 K). Nitrosyl complex 2 is unstable in solution and loses its NO group to yield [Ir(cod)(dpp-bian)](BF₄) (3). A paramagnetic complex, [Ir(cod)(dpp-bian)](BF₄)₂ (4), was also detected in the solution of 2 as a result of its decomposition. The EPR spectrum of 4 in CH₂Cl₂ is described by the spin Hamiltonian Ĥ = gβHŜ with S = 1/2 and g_xx = g_yy = 2.393 and g_zz = 1.88, which are characteristic of the low-spin 5d⁷-Ir(II) state. DFT calculations were carried out in order to rationalize the experimental results. Full article