Long-Range Structural Order in a Hidden Phase of Ruddlesden-Popper Bilayer Nickelate La3Ni2O7.

The recent discovery of superconductivity in the Ruddlesden-Popper bilayer nickelate, specifically La3Ni2O7, has generated significant interest in the exploration of high-temperature superconductivity within this material family. In this study, we present the crystallographic and electrical resistivity properties of two distinct Ruddlesden-Popper nickelates: the bilayer La3Ni2O7 (referred to as 2222-phase) and a previously uncharacterized phase, La3Ni2O7 (1313-phase). The 2222-phase is characterized by a pseudo F-centered orthorhombic lattice, featuring bilayer perovskite [LaNiO3] layers interspaced by rock salt [LaO] layers, forming a repeated ...2222... sequence. Intriguingly, the 1313-phase, which displays semiconducting properties, crystallizes in the Cmmm space group and exhibits a pronounced predilection for a C-centered orthorhombic lattice. Within this structure, the perovskite [LaNiO3] layers exhibit a distinctive long-range ordered arrangement, alternating between single- and trilayer configurations, resulting in a ...1313... sequence. This report contributes to novel insights into the crystallography and the structure-property relationship of Ruddlesden-Popper nickelates, paving the way for further investigations into their unique physical properties.

Fast Low-Sidelobe Pattern Synthesis Using the Symmetry of Array Geometry.

Array pattern synthesis with low sidelobe levels is widely used in practice. An effective way to incorporate sensor patterns in the design procedure is to use numerical optimization methods. However, the dimension of the optimization variables is very high for large-scale arrays, leading to high computational complexity. Fortunately, sensor arrays used in practice usually have symmetric structures that can be utilized to accelerate the optimization algorithms. This paper studies a fast pattern synthesis method by using the symmetry of array geometry. In this method, the problem of amplitude weighting is formulated as a second-order cone programming (SOCP) problem, in which the dynamic range of the weighting coefficients can also be taken into account. Then, by utilizing the symmetric property of array geometry, the dimension of the optimization problem as well as the number of constraints can be reduced significantly. As a consequence, the computational efficiency is greatly improved. Numerical experiments show that, for a uniform rectangular array (URA) with 1024 sensors, the computational efficiency is improved by a factor of 158, while for a uniform hexagonal array (UHA) with 1261 sensors, the improvement factor is 284.

Disorder-Enriched Magnetic Excitations in a Heisenberg-Kitaev Quantum Magnet Na_{2}Co_{2}TeO_{6}.

Using optical magnetospectroscopy, we investigate the magnetic excitations of Na_{2}Co_{2}TeO_{6} in a broad magnetic field range (0 T≤B≤17.5 T) at low temperature. Our measurements reveal rich spectra of in-plane magnetic excitations with a surprisingly large number of modes, even in the high-field spin-polarized state. Theoretical calculations find that the Na-occupation disorder in Na_{2}Co_{2}TeO_{6} plays a crucial role in generating these modes. Our Letter demonstrates the necessity to consider disorder in the spin environment in the search for Kitaev quantum spin liquid states in practicable materials.

Continuous Spin Excitations in the Three-Dimensional Frustrated Magnet K_{2}Ni_{2}(SO_{4})_{3}.

Continuous spin excitations are widely recognized as one of the hallmarks of novel spin states in quantum magnets, such as quantum spin liquids (QSLs). Here, we report the observation of such kind of excitations in K_{2}Ni_{2}(SO_{4})_{3}, which consists of two sets of intersected spin-1 (Ni^{2+}) trillium lattices. Our inelastic neutron scattering measurement on single crystals clearly shows a dominant excitation continuum, which exhibits a distinct temperature-dependent behavior from that of spin waves, and is rooted in strong quantum spin fluctuations. Further using the self-consistent-Gaussian-approximation method, we determine that the fourth- and fifth-nearest-neighbor exchange interactions are dominant. These two bonds together form a unique three-dimensional network of corner-sharing tetrahedra, which we name as a "hypertrillium" lattice. Our results provide direct evidence for the existence of QSL features in K_{2}Ni_{2}(SO_{4})_{3} and highlight the potential for the hypertrillium lattice to host frustrated quantum magnetism.

Membrane separation of antibiotics predicted with the back propagation neural network.

Antibiotics and antibiotic resistance genes (ARGs) have been frequently detected in the aquatic environment and are regarded as emerging pollutants. The prediction models for the removal effect of four target antibiotics by membrane separation technology were constructed based on back propagation neural network (BPNN) through training the input and output. The membrane separation tests of antibiotics showed that the removal effect of microfiltration on azithromycin and ciprofloxacin was better, basically above 80%. For sulfamethoxazole (SMZ) and tetracycline (TC), ultrafiltration and nanofiltration had better removal effects. There was a strong correlation between the concentrations of SMZ and TC in the permeate, and the R2 of the training and validation processes exceeded 0.9. The stronger the correlation between the input layer variables and the prediction target was, the better the prediction performances of the BPNN model than the nonlinear model and the unscented Kalman filter model were. These results showed that the established BPNN prediction model could better simulate the removal of target antibiotics by membrane separation technology. The model could be used to predict and explore the influence of external conditions on membrane separation technology and provide a certain basis for the application of the BPNN model in environmental protection.

Effect of barbed versus standard sutures on wound complications in total knee arthroplasty: A meta-analysis.

A barbed suture has been demonstrated to be effective in shortening the stitching time and improving the aesthetic appearance of the stitches during the entire knee replacement. However, no meta-analyses have been conducted specifically to evaluate the effect of the barbed thread on wound complications relative to the conventional suture. A comprehensive search of the PubMed database, the Embase database, the Cochrane Library and the Web of Science was performed to obtain search data up to June 2023, and only randomised controlled trials were included in this meta-analysis. We used Review Manager 5.3 for data synthesis and analysis. This meta-analysis included eight studies. It was found that the use of barbed sutures did not improve the incidence of the disease, the infection of the wound, the closure of the abscess and the injury. However, because of the limited sample size of the randomised controlled trials for this meta-analysis, the data should be handled with caution. More high-quality, large-sample studies will be required to confirm the results.

Controllable Emergent Spatial Spin Modulation in Sr_{2}IrO_{4} by In Situ Shear Strain.

Symmetric anisotropic interaction can be ferromagnetic and antiferromagnetic at the same time but for different crystallographic axes. We show that the competition of anisotropic interactions of orthogonal irreducible representations can be a general route to obtain new exotic magnetic states. We demonstrate it here by observing the emergence of a continuously tunable 12-layer spatial spin modulation when distorting the square-lattice planes in the quasi-two-dimensional antiferromagnetic Sr_{2}IrO_{4} under in situ shear strain. This translation-symmetry-breaking phase is a result of an unusual strain-activated anisotropic interaction which is at the fourth order and competing with the inherent quadratic anisotropic interaction. Such a mechanism of competing anisotropy is distinct from that among the ferromagnetic, antiferromagnetic, and/or the Dzyaloshinskii-Moriya interactions, and it could be widely applicable and highly controllable in low-dimensional magnets.

Real-time observation of the thermo-optical and heat dissipation processes in microsphere resonators.

This work reports the real-time observation of the thermo-optical dynamics in silica microsphere resonators based on the dispersive time stretch technique. In general, the thermo-optical dynamics of silica microsphere resonators, including the thermal refraction and thermal expansion, can be characterized by the resonance wavelength shift, whose duration is at the millisecond timescale. However, this fast wavelength shift process cannot be directly captured by conventional spectroscopy, and only its transmission feature can be characterized by a fast-scanning laser and an intensity detector. With the advance of the time-stretch spectroscopy, whose temporal resolution is up to tens of nanoseconds, the thermo-optical dynamics can be observed in a more straight-forward way, by utilizing the pump-probe technology and mapping the resonance wavelength to the time domain. Here, the thermo-optical dynamics are explored as a function of the power and the scanning rate of the pump laser. Theoretical simulations reproduce the experimental results, revealing that the thermo-optical dynamics of silica microsphere resonators is dominated by the fast thermo-optical effect and the slow heat dissipation process to the surroundings, which leads to gradual regression of the resonance wavelength. This work provides an alternative solution for studying the thermo-optical dynamics in whispering gallery mode microresonators, which would be crucial for future applications of microresonator photonic systems.

Freezing of a Disorder Induced Spin Liquid with Strong Quantum Fluctuations.

Sr_{2}CuTe_{0.5}W_{0.5}O_{6} is a square-lattice magnet with superexchange between S=1/2Cu^{2+} spins mediated by randomly distributed Te and W ions. Here, using sub-K temperature and 20 µeV energy resolution neutron scattering experiments we show that this system transits from a gapless disorder-induced spin liquid to a new quantum state below T_{f}=1.7(1) K, exhibiting a weak frozen moment of ⟨S⟩/S∼0.1 and low energy dynamic susceptibility, χ^{''}(ℏω), linear in energy which is surprising for such a weak freezing in this highly fluctuating quantum regime.

Superconductivity in Metal-Rich Chalcogenide Ta2Se.

The metal-metal bond in metal-rich chalcogenide is known to exhibit various structures and interesting physical properties. Ta2Se can be obtained by both arc-melting and solid-state pellet methods. Ta2Se crystallizes a layered tetragonal structure with space group P4/nmm (No. 129; Pearson symbol tP6). Each unit cell consists of four layers of body-centered close-packing Ta atoms sandwiched between two square nets of Se atoms, forming the Se-Ta-Ta-Ta-Ta-Se networks. Herein, we present magnetic susceptibility, resistivity, and heat capacity measurements on Ta2Se, which together indicate bulk superconductivity with Tc = 3.8(1) K. According to first-principles calculations, the d orbitals in Ta atoms dominate the Fermi level in Ta2Se. The flat bands at the Γ point in the Brillouin zone yield the van Hove singularities in the density of states around the Fermi level, which is intensified by introducing a spin-orbit coupling effect, and thus could be critical for the superconductivity in Ta2Se. The physical properties, especially superconductivity, are completely different from those of Ta-rich alloys or transition-metal dichalcogenide TaSe2.

Large Positive Zero-Field Splitting in the Cluster Magnet Ba3CeRu2O9.

We present the synthesis and magnetic characterization of a polycrystalline sample of the 6H-perovskite Ba3CeRu2O9, which consists of Ru dimers based on face-sharing RuO6 octahedra. Our low-temperature magnetic susceptibility, magnetization, and neutron powder diffraction results reveal a nonmagnetic singlet ground state for the dimers. Inelastic neutron scattering, infrared spectroscopy, and the magnetic susceptibility over a wide temperature range are best explained by a molecular orbital model with a zero-field splitting parameter D = 85 meV for the Stot = 1 electronic ground-state multiplet. This large value is likely due to strong mixing between this ground-state multiplet and low-lying excited multiplets, arising from a sizable spin molecular orbital coupling combined with an axial distortion of the Ru2O9 units. Although the positive sign for the splitting ensures that Ba3CeRu2O9 is not a single molecule magnet, our work suggests that the search for these interesting materials should be extended beyond Ba3CeRu2O9 to other molecular magnets based on metal-metal bonding.

Aging, memory, and nonhierarchical energy landscape of spin jam.

The notion of complex energy landscape underpins the intriguing dynamical behaviors in many complex systems ranging from polymers, to brain activity, to social networks and glass transitions. The spin glass state found in dilute magnetic alloys has been an exceptionally convenient laboratory frame for studying complex dynamics resulting from a hierarchical energy landscape with rugged funnels. Here, we show, by a bulk susceptibility and Monte Carlo simulation study, that densely populated frustrated magnets in a spin jam state exhibit much weaker memory effects than spin glasses, and the characteristic properties can be reproduced by a nonhierarchical landscape with a wide and nearly flat but rough bottom. Our results illustrate that the memory effects can be used to probe different slow dynamics of glassy materials, hence opening a window to explore their distinct energy landscapes.

Landau Quantization in Coupled Weyl Points: A Case Study of Semimetal NbP.

Weyl semimetal (WSM) is a newly discovered quantum phase of matter that exhibits topologically protected states characterized by two separated Weyl points with linear dispersion in all directions. Here, via combining theoretical analysis and magneto-infrared spectroscopy of an archetypal Weyl semimetal, niobium phosphide, we demonstrate that the coupling between Weyl points can significantly modify the electronic structure of a WSM and provide a new twist to the protected states. These findings suggest that the coupled Weyl points should be considered as the basis for analysis of realistic WSMs.

Effects and control of metal nutrients and species on Microcystis aeruginosa growth and bloom.

The effects and control of typical metal nutrients, copper, iron, and zinc, on the growth and bloom of Microcystis aeruginosa were investigated with a series of flask-shaking tests. The optimal concentrations of copper, iron, and zinc for algal growth were 0.001, 3-12, and 0.05 mg/L, respectively. The order of toxicity to the alga was Cu > Zn > Fe. The effects of the species, for a trace metal at the same concentrations, on the growth of M. aeruginosa were relatively remarkable. Ionic and complexation species induced more algal growth than the carbonate and sulfide-bound species. Changes in copper concentration and iron species were adopted to adjust and control the bloom of M. aeruginosa. Increases in copper concentrations significantly suppressed the M. aeruginosa bloom. The growth rate of M. aeruginosa slowed significantly when ionic iron was replaced with sulfide-bound iron, and the control of bloom was remarkable. PRACTITIONER POINTS: Using trace metal nutrient species and concentration to regulate and control algal growth and bloom may pave another way for the management of cyanobacterial bloom.

Evidence for Dyakonov-Perel-like Spin Relaxation in Pt.

We utilize nanoscale spin valves with Pt spacer layers to characterize spin relaxation in Pt. Analysis of the spin lifetime indicates that Elliott-Yafet spin scattering is dominant at room temperature, but an unexpected intrinsic Dyakonov-Perel-like spin relaxation becomes dominant at cryogenic temperatures. We also observe suppression of spin relaxation in a Pt layer interfaced with a ferromagnet, likely caused by the competition between the effective exchange and spin-orbit fields.

Probing disorder in isometric pyrochlore and related complex oxides.

There has been an increased focus on understanding the energetics of structures with unconventional ordering (for example, correlated disorder that is heterogeneous across different length scales). In particular, compounds with the isometric pyrochlore structure, A2B2O7, can adopt a disordered, isometric fluorite-type structure, (A, B)4O7, under extreme conditions. Despite the importance of the disordering process there exists only a limited understanding of the role of local ordering on the energy landscape. We have used neutron total scattering to show that disordered fluorite (induced intrinsically by composition/stoichiometry or at far-from-equilibrium conditions produced by high-energy radiation) consists of a local orthorhombic structural unit that is repeated by a pseudo-translational symmetry, such that orthorhombic and isometric arrays coexist at different length scales. We also show that inversion in isometric spinel occurs by a similar process. This insight provides a new basis for understanding order-to-disorder transformations important for applications such as plutonium immobilization, fast ion conduction, and thermal barrier coatings.

Real-time broadband radio frequency spectrum analyzer based on parametric spectro-temporal analyzer (PASTA).

A real-time broadband radio frequency (RF) spectrum analyzer is proposed and experimentally demonstrated to rapidly measure the RF spectrum of broadband optical signal. Cross phase modulation in the highly-nonlinear fiber is used to convert the RF spectrum carried by the pump to the optical spectrum of the probe signal, then the optical spectrum is real-time analyzed with the parametric spectro-temporal analyzer (PASTA) technology. The system performances are investigated in detail, including bandwidth, resolution, frame rate, and dynamic range. It achieves large RF bandwidth of over 800 GHz, as well as 91-MHz frame rate without sacrificing the resolution. It is noted that 91-MHz frame rate is several orders of magnitude improvement over those previous reported all-optical RF spectrum analyzers. As a proof-of-concept demonstration, this real-time broadband RF spectrum analyzer successfully characterizes the ultra-short pulse trains with repetition rate of 160GHz, which is far beyond capability of the conventional electrical spectrum analyzer. It presents a new way to implement rapid and broadband RF spectrum measurement, and would be of great interests for some ultrafast scenarios, where the real-time RF spectrum analysis can be applied.

Ultrafast electrical spectrum analyzer based on all-optical Fourier transform and temporal magnification.

Real-time electrical spectrum analysis is of great significance for applications involving radio astronomy and electronic warfare, e.g. the dynamic spectrum monitoring of outer space signal, and the instantaneous capture of frequency from other electronic systems. However, conventional electrical spectrum analyzer (ESA) has limited operation speed and observation bandwidth due to the electronic bottleneck. Therefore, a variety of photonics-assisted methods have been extensively explored due to the bandwidth advantage of the optical domain. Alternatively, we proposed and experimentally demonstrated an ultrafast ESA based on all-optical Fourier transform and temporal magnification in this paper. The radio-frequency (RF) signal under test is temporally multiplexed to the spectrum of an ultrashort pulse, thus the frequency information is converted to the time axis. Moreover, since the bandwidth of this ultrashort pulse is far beyond that of the state-of-the-art photo-detector, a temporal magnification system is applied to stretch the time axis, and capture the RF spectrum with 1-GHz resolution. The observation bandwidth of this ultrafast ESA is over 20 GHz, limited by that of the electro-optic modulator. Since all the signal processing is in the optical domain, the acquisition frame rate can be as high as 50 MHz. This ultrafast ESA scheme can be further improved with better dispersive engineering, and is promising for some ultrafast spectral information acquisition applications.

Subtenon Vs Intravitreal Triamcinolone injection in Diabetic Macular Edema, A prospective study in Chinese population.

OBJECTIVE: Purpose of this study was to validate that Subtenon (SB) Triamcinolone (TA) injection is an alternative to Intravitreal (IV) Triamcinolone (TA) injection for the treatment of diabetic macular edema (DME). METHODS: Forty eyes were selected having DME due to type 1 or type 2 diabetes. All the patients were treated with photocoagulation. IVTA was administered in one eye and SBTA in following eye of same patient. Improvement in visual acuity, macular edema and intraocular pressure was assessed before treatment and on 2(nd), 4(th), 8(th) and 12(th) week after treatment. RESULTS: After administration of IVTA, MVA was reduced from baseline value (0.805 ± 0.069Log/MAR) to (0.577 ± 0.091 Log/MAR, p<.001) at the end of treatment. Similar results were observed after SBTA administration. MVA was reduced from (0.814 ± 0.082Log/MAR) to (0.49 ± 0.080 Log/MAR, p<.001) at 12(th) week. After IVTA injection Central macular thickness was significantly reduced to (246.8 ± 25 µm, p<0.001) from (390.5 ± 17 µm). There were no significant (p=0.51) difference in both eyes receiving different routes of same treatment. After SBTA injection CMT was significantly reduced to lower values (241.5 ± 27 µm, p<0.001) from (394.4 ± 21 µm). Intraocular pressure after IVTA administration was high (2.32 ± 0.72 mm/Hg, p=0.04) as compared to baseline (1.82 ± 0.94 mm/Hg). Similar pattern was also seen after SBTA administration but to significant extent. Elevation of IoP was observed in both eyes. CONCLUSION: Subtenon Triamcinolone injection is an alternative to Intravitreal Triamcinolone Injection for Diabetic Macular Edema.

Modification of polyvinylidene fluoride membrane with ciprofloxacin to improve the bacteriostatic performance.

The common polyvinylidene fluoride (PVDF) membrane itself is susceptible to membrane fouling, especially biofouling, which is a serious threat. In this study, PVDF membrane was modified with ciprofloxacin (CIP) through co-blending to investigate the filtration properties, bacterial inhibition and fouling resistance. Modified membranes were prepared by adding 0.3 g (MC0.3), 0.6 g (MC0.6), 0.9 g (MC0.9) and 1.2 g (MC1.2) CIP per 100 g casting solution. Among these modified membranes, MC0.6 showed the best filtration performances, with the pure water flux stabilized at about 416.67 L/(m2·h) and bovine serum albumin (BSA) rejection of 92.0% at a trans-membrane pressure of 0.1 MPa. The pore size was reduced, the average roughness was reduced to 29.4 nm, the contact angle was lowered to 68.9°, and the hydrophilicity was greatly improved. The width of the inhibition circle produced by MC0.6 was 0.35-0.45 mm, and the modified membrane showed good inhibition of non-specific bacteria and algal removal during urban river water filtration. The rejection of BSA was increased by 16.32% compared to the base membrane and the adsorption rate for BSA was reduced by 68.45%. In addition, the removal of conventional pollutants in urban river water by the modified membranes for was also improved. Compared with that of the base membrane, the removal of TN, NH3-N, TP and COD by MC0.6 was increased by 10.58%, 12.45%, 15.44% and 13.53%. The results showed that CIP co-blending modified PVDF membrane could effectively improve membrane performances and has good value for water treatment.