Crystal structure of KMnPO4F with short- and long-range order inside the layered magnetic system.

Potassium manganese fluoride phosphate, KMnPO4F, has been obtained through mild hydrothermal synthesis and characterized by scanning electron microscopy, microprobe analysis and X-ray diffraction. The compound possesses an orthorhombic symmetry and chiral space group P212121 with a = 4.7884(2), b = 9.0172(4), c = 9.5801(4) Å, and Z = 4. Its crystal structure is composed of Mn3+O4F square pyramids sharing vertices with PO4 tetrahedra. This anionic framework is neutralized by K+ cations. As the temperature decreases, a short-range correlation state (Tmax ∼ 35 K) of KMnPO4F is formed, followed by the establishment of antiferromagnetic (AFM) long-range order at TN = 25 K. The latter is marked by sharp λ-type anomalies in both Fisher's specific heat d(χ‖T)/dT and heat capacity Cp. Pulsed magnetic field measurements on the single crystals identify the a axis as the easy magnetic axis and reveal a spin-flop transition at µ0Hspin-flop = 19 T. Density functional theory indicates that in variance with the three-dimensional network of KMnPO4F, it is a two-dimensional Ising magnetic system represented by buckled layers of integer spins S = 2 of Mn3+ ions. The strongest AFM exchange interaction, J1 ∼ -13 K, couples Mn3+ ions into linear chains running along the a axis. The chains themselves are ferromagnetically connected (J3 ∼ -4 K) within the ab plane. The interplane AFM exchange interaction (J2 ∼ -1 K) is weak and frustrated.

Preparation and Properties of a High-Entropy Wolframite-Type Antiferromagnet, (Mn0.2Co0.2Ni0.2Cu0.2Cd0.2)WO4.

The homogeneous high-entropy wolframite-type solid solution (Mn1/5Co1/5Ni1/5Cu1/5Cd1/5)WO4 was prepared by solid-state reaction at 1000 °C. Elongated "crystals" were grown from the Na2WO4 flux, but their strongly broadened powder X-ray diffraction patterns indicated partial dissolution. Nevertheless, successive annealing of the homogeneous solid solution for 3-4 h at 800, 700, and 600 °C did not bring any sign of dissolution. Thus, the material is kinetically stable at low temperatures although thermodynamically unstable. The long-range antiferromagnetic order was established at TN ∼ 24.8 K. Based on magnetization and specific heat measurements, a magnetic phase diagram was built, demonstrating the presence of an additional field-induced phase. In contrast to the parent MnWO4, no dielectric anomaly has been found down to 2 K.

Spin-Cluster Glassy and Long-Range Ordered Magnetic States in Honeycomb-Layered Compositionally Complex Oxides Na3-xLixT2SbO6 (T = Cu1/3Ni1/3Co1/3).

The concept of high-entropy oxides has triggered extensive research of this novel class of materials because their numerous functional properties are usually not mere linear combinations of those of the components. Here, we introduce the new series of compositionally complex honeycomb-layered magnets Na3-xLixT2SbO6 (T = Cu1/3Ni1/3Co1/3). An unusual feature of the system is its nonmonotonous dependences of the monoclinic lattice parameters b and ß on x. Rietveld refinement of the crystal structures of the Na and Li end members reveals apparent Sb-T site inversion in the former and considerable Li-Cu site inversion in the latter. The materials are characterized by measurements of specific heat Cp, magnetization M, and ac and dc magnetic susceptibility χ. Na3T2SbO6 exhibits sharp long-range antiferromagnetic order (TN = 10.2 K) preceded by noticeable correlation effects at elevated temperatures. The magnetic phase diagram of Na3T2SbO6 is established. Introduction of Li, just at x = 0.8, destroys AFM order, resulting in spin-cluster glass behavior attributed to Li/Cu inversion, with TG growing with x to 10.4 K at x = 3.

Sequence of Structural and Magnetic Phase Transitions in (NO)Mn6(NO3)13.

New nitrosonium manganese(II) nitrate, (NO)Mn6(NO3)13, has been synthesized and structurally characterized. In the temperature range of 45-298 K, the crystal is hexagonal (centrosymmetric sp. gr. P63/m). Mn2+ ions are assembled into tubes along axis c with both NO3- filling and coating. The nitrosonium cation is located in the framework cavity and is disordered by a 3-fold axis. At the temperature TS1 = 190 K, a structural phase transition related to the libration of the intertube NO3 group and a small variation of Mn polyhedron is observed. Moreover, the anomalies in physical properties of (NO)Mn6(NO3)13 allow suggesting that ordering of NO+ units occurs at low temperatures. The antiferromagnetic ordering in this compound is preceded by the formation of a short-range correlation regime at about 25 K and takes place in two steps at TN1 = 12.0 K and TN2 = 8.4 K.

Safety and Efficacy of Photodynamic Therapy with Chlorin E6 in Chronic Central Serous Chorioretinopathy.

PURPOSE: To evaluate the efficacy and safety of photodynamic therapy (PDT) with chlorin E6 in chronic central serous chorioretinopathy (CSCR). METHODS: This single-center, retrospective cohort study. All patients received standard PDT with 6 mg of chlorin E6 (Fotoran E6) for each m2 of body surface area with 50 J/cm2 fluence and a treatment time of 83 seconds. The changes in central retinal thickness (CRT), subfoveal choroidal thickness (SCT), and best-corrected visual acuity (BCVA) were evaluated at the end of the follow-up. Main outcome measure was the presence of subretinal fluid (SRF) at three months after PDT. RESULTS: Thirty-nine eyes (32 males and 7 females, 43.7 ± 10.0 years) were included. In total, 50 PDT sessions were performed. At three months of follow-up, 31 out of 39 (79.5%) study eyes showed complete resolution of SRF. Mean follow-up period after PDT was 15.3 ± 7.8 months. At the end of follow-up, a complete resolution of SRF was observed in 32 out of 39 (82.7%) eyes. Mean change in CRT, SCT, and BCVA at the end of the follow-up was -139.7 ± 136.4 µm, -66.8 ± 36.2 µm, and -0.05 ± 0.08 LogMAR, respectively (p < 0.001). Neither systemic nor ocular adverse events were observed, nor were local reactions seen. CONCLUSION: Standard PDT with chlorin E6 is an effective and safe option in the management of chronic CSCR and may be considered as an alternative to the standard PDT with Visudyne.

Lamellar Crystal Structure and Haldane Magnetism in NH4 VPO4 OH.

A novel vanadium hydroxide-phosphate, NH4 VPO4 OH, was synthesized hydrothermally in V2 O5 -NH4 H2 PO4 -citric acid system at 230 °C. It was characterized by XRD, TG-DSC, SEM-EDX, FTIR and NMR spectroscopy. NH4 VPO4 OH is isostructural with NH4 GaPO4 OH and features edge-sharing chains of VO6 octahedra. These chains running along [010] direction of the unit cell are connected by phosphate tetrahedra to form infinite layers parallel to the (100) plane. Ammonium cations are embedded between the heteropolyhedral layers. According to the thermodynamic and NMR measurements supported by the first-principles calculations, NH4 VPO4 OH presents a rare case of Haldane spin system with spin S=1 based on V3+ ions.

Thermodynamic Properties and DFT Study on Highly Frustrated Cr3BO6: Coexistence of Spin-Singlets with Long-Range Magnetic Order.

The triangle-based magnetic subsystem of borates with the mineral norbergite structure M3BO6 (M = Fe, Cr, V) makes these compounds unique to investigate rare quantum ground states influenced by strong magnetic frustration. In this work, we investigated the thermal and magnetic properties of Cr3BO6 to find that despite very large negative Weiss temperature Θ = -160.7 K, it orders only at TN = 4.5 K and experiences a spin-flop transition at µ0H = 5 T. Density functional theory (DFT) calculations of exchange interaction parameters allow for suggesting the model of magnetic subsystem in chromium borate Cr3BO6. The results prove the decisive role of magnetic frustration on the formation of long-range order, providing therefore a basis for future study. Both experimental data and first-principles calculations point to the coexistence of chromium spin-singlets with long-range antiferromagnetic order.

A Dy-based single ion magnet in a SrLaGaO4 matrix: enhanced parameters in an expanded crystal lattice.

Dy3+ doped SrLaGaO4 exhibits unusually slow relaxation of magnetization determined by two widely separated excited Kramers doublets with a second remagnetization energy barrier of 223 cm-1. This value considerably exceeds that for analogous Ca(Y,Dy)AlO4 in spite of the apparently enlarged Dy3+ coordination sphere.

Composite Polymer Granules Based on Poly-ε-Caprolactone and Montmorillonite Prepared by Solution-Casting and Melt Extrusion.

Eco-friendly polymer composites in the form of granules based on biodegradable polycaprolactone (PCL) with the inclusion of montmorillonite (MMT) from 5 to 50 wt% were prepared by solution-casting and melt extrusion. The physicochemical properties of the composite granules were studied using FTIR spectroscopy, XRDA, DSC, and TGA methods. The paper presents comparative values of crystallinity of composite granules which depend on the method of measuring (XRDA, DSC). It was shown that the crystallinity of PCL/MMT granules was affected by the preparation method and by the MMT content, and that with increase in MMT content, crystallinity increased by up to 61-67%. The change in crystallinity of the granules also affected its biodegradation in soil. At the end of exposure in soil, the mass loss for the granules prepared by solution-casting was more than 90%, whereas for the composite granules prepared by extrusion it was less than 60%. Applying melt extrusion enabled obtaining intercalated composites with predictable features, whereas only mixed-structure microcomposites could be prepared by solution-casting.

Synthesis and Characterization of Molybdenum- and Sulfur-Doped FeSe.

During the past decade, two-dimensional (2D) layered materials opened novel opportunities for the exploration of exciting new physics and devices owing to their physical and electronic properties. Among 2D materials, iron selenide has attracted much attention from several physicists as they provide a fruitful stage for developing new superconductors. Chemical doping offers a powerful approach to manipulate and optimize the electronic structure and physical properties of materials. Here, to reveal how doping affects the physical properties in FeSe, we report on complementary measurements of molybdenum- and sulfur-doped FeSe with theoretical calculations. Mo0.1Fe0.9Se0.9S0.1 was synthesized by a one-step solid-state reaction method. Crystal structure and morphology were studied using powder X-ray diffraction and scanning electron microscopy. Thermal stability and decomposition behavior in doped samples were studied by thermogravimetric analysis, and to understand the microscopic influence of doping, we performed Raman spectroscopy. First-principles calculations of the electronic structure illustrate distinct changes of electronic structures of the substituted FeSe systems, which can be responsible for their superconducting properties.

Efficacy and Safety of Cataract Surgery-Assisted Selective Laser Trabeculoplasty: A Pilot Study.

Purpose: To evaluate the intraocular pressure (IOP)-lowering effect and safety of selective laser trabeculoplasty (SLT) with same-day cataract surgery which we named cataract surgery-assisted selective laser trabeculoplasty (CAST) compared to conventional SLT and cataract surgery as standalone procedures. Methods: Patients with primary open-angle glaucoma and cataract were included in this prospective interventional study. All patients received either a CAST procedure, standard SLT, or standard cataract surgery. IOP was assessed at baseline and at months 1, 2, 3, and 6. Topical IOP-lowering medication was canceled during the follow-up if necessary. Results: Twenty-nine, twenty-seven, and thirty eyes received the CAST procedure, SLT, and standard cataract surgery, respectively. There was no statistically significant difference in age, male-to-female ratio, or baseline IOP between groups (P > 0.05). The mean IOP reduction at 6 months after the CAST procedure, SLT, and standard cataract surgery was -7.3 ± 3.8 mmHg, -3.8 ± 3.7 mmHg, and -0.7 ± 3.7 mmHg, respectively (P < 0.001). Eleven out of 29 (37.9%) and 5 out of 27 (18.5%) eyes achieved 30% reduction of IOP after the CAST procedure and SLT, respectively. No eyes achieved 30% reduction of IOP at the end of the follow-up in cataract surgery group. The median number of IOP-lowering medications cancelled after the CAST procedure was 1.0 (range, 0-3). No antiglaucoma medication was cancelled after SLT or cataract surgery. No adverse events were registered in patients who received the CAST procedure. Conclusion: At 6-month follow-up, the CAST procedure had a significantly greater IOP-lowering effect and reduction of topical antiglaucoma medication than SLT or cataract surgery alone.

K2Mn3O(OH)(VO4)(V2O7) with Sawtooth Chains of Multivalent Manganese Triangular Trimer Units: Magnetic Susceptibility Shrouding a Long-Range Antiferromagnetic Order of Ferromagnetic Triangles.

ortho-Pyrovanadate (or ortho-diorthovanadate) K2Mn23+Mn2+O(OH)(VO4)(V2O7) synthesized hydrothermally crystallizes in the orthorhombic space group Pnma with a = 17.9155(5), b = 5.8940(2), c = 10.9971(3) Å, V = 1161.23(6) Å3, and Z = 4. Its crystal structure features linear chains of edge-sharing Mn3+O6 octahedra with every second pair of Mn3+O6 octahedra condensed with a Mn2+O6 octahedron on one side of a chain in a sawtooth pattern so that each sawtooth chain consists of a triangular trimer. These sawtooth chains, running parallel to the b axis and linked by the VO4 and V2O7 groups, form a framework with channels populated by K atoms. The new compound is a structural analogue of the mineral zoisite Ca2Al3O(OH)(SiO4)(Si2O7), showing a striking example of very different chemical compositions. K2Mn3O(OH)(VO4)(V2O7) undergoes a phase transition into an ordered antiferromagnetic (AFM) state at TN = 14.4 K, which was detected by high-frequency electron spin resonance as well as by both specific heat Cp and Fisher's specific heat d(χT)/dT measurements. However, this phase transition was not detected by magnetic susceptibility measurements. The origin of this puzzling observation was resolved by evaluating the spin exchanges of K2Mn3O(OH)(VO4)(V2O7), which revealed that each triangular trimer is a ferromagnetically coupled cluster, and the observed ordering involves an AFM ordering between the ferromagnetic (FM) clusters. This ordering is shrouded in magnetic susceptibility measurements due to the susceptibility contributions from the individual FM triangular trimers even below TN. We showed that the magnetic susceptibility of K2Mn3O(OH)(VO4)(V2O7) between ∼30 K and room temperature is satisfactorily described by an AFM chain made up of ferromagnetically coupled triangular clusters, as described by a few spin-exchange parameters.

Spotlight on Lattice Degeneration Imaging Techniques.

Lattice degeneration (LD), routinely diagnosed with indirect ophthalmoscopy, is one of the most common and clinically significant peripheral retinal findings. In this review, we have summarized the data on currently available imaging techniques which help to improve diagnosis and our understanding of LD pathogenesis. Ultra-wide field imaging provides reliable color fundus capturing for the primary diagnosis of LD and may also be used as a screening tool. Wide-field imaging can be used for targeted documentation of LD lesions using true colors and with minimal optical distortions. Information on the status of the vitreoretinal interface, including detection of retinal holes, detachments, and vitreous tractions, can be obtained with peripheral structural optical coherence tomography (OCT) or scanning laser ophthalmoscopy in retro-mode. These techniques clarify the associated risks of rhegmatogenous retinal detachment. Fundus autofluorescence can provide details on atrophic changes. However, the risk of retinal detachment by means of this technique requires further investigation. OCT angiography may be successfully performed for some lesions. Taken together, OCT and OCT angiography demonstrate thinning of the choroid, alteration of local choroidal microcirculation, and, in severe lesions, involvement of the sclera. OCT angiography confirms loss of retinal microcirculation within LD lesion, which was previously shown with fluorescein angiography. In conclusion, despite relatively simple primary diagnosis, imaging of LD lesions remains challenging due to their peripheral localization. However, several new strategies, including ultra-wide field imaging, peripheral OCT, and scanning laser ophthalmoscopy, make LD imaging possible on a routine basis, improving diagnosis and understanding of LD pathogenesis.

Prevalence of choroidal nevi in patients with central serous chorioretinopathy.

Background: A number of articles report the association of polypoidal lesions and choroidal nevi; however, the relationship between choroidal nevi and pachychoroidal disorders has not been studied. Objectives: To study the prevalence of choroidal nevi in central serous chorioretinopathy (CSCR) patients and to elucidate potential differences in the clinical characteristics of CSCR in patients with and without choroidal nevi. Design: Case-control study. Methods: This study included a retrospective analysis of medical records and multimodal imaging data of CSCR patients and a prospective evaluation of the prevalence of the choroidal nevi in age- and sex-matched healthy controls. All participants received comprehensive ophthalmic examination and multimodal imaging including infrared scanning laser ophthalmoscopy in dark-field mode to detect choroidal nevi in the central 40° × 60° region. Results: A total of 199 CSCR patients (160 males and 39 females, 47.9 ± 9.4 years) and 184 age-matched healthy individuals (139 males and 45 females, 44.8 ± 12.5 years) were included. Choroidal nevi were detected in 24 (12.1%) CSCR patients and 10 (5.4%) healthy controls (p = 0.01). CSCR patients with choroidal nevi had statistically significantly higher subfoveal choroidal thickness, lower best-corrected visual acuity, and lower central retinal thickness (p < 0.05) than CSCR patients without choroidal nevi. The odds ratio for the presence of chronic CSCR in patients with choroidal nevi was 27.0 (95% CI: 3.1-231.9, p = 0.003). Conclusion: The prevalence of choroidal nevi among patients with CSCR is higher than in age- and sex-matched healthy population. Choroidal nevi may be associated with chronic CSCR.

MULTIMODAL IMAGING IN NONEXUDATIVE CHOROIDAL NEOVASCULARIZATION: A Pilot Study of Status of Retinal Pigment Epithelium.

PURPOSE: To study the status of retinal pigment epithelium in nonexudative and active choroidal neovascularization (CNV) in neovascular age-related macular degeneration. METHODS: Only treatment-naïve neovascular age-related macular degeneration patients were enrolled in this prospective case-control study, including 17 eyes with nonexudative CNV (6 males and 11 females, 74.9 ± 10.0 years) and 28 eyes with active CNV (8 males and 20 females, 69.3 ± 6.8 years). All patients received a comprehensive ophthalmic examination, optical coherence tomography, dark-field scanning laser ophthalmoscopy, and fundus autofluorescence. The status of the retinal pigment epithelium was assessed with ImageJ software as the brightness of the CNV region on transillumination optical coherence tomography, dark-field scanning laser ophthalmoscopy, and fundus autofluorescence images. Choroidal neovascularization vessel density was measured based on optical coherence tomography angiography. RESULTS: The brightness of CNV region in nonexudative CNV was statistically significantly lower than in active CNV with both optical coherence tomography transillumination ( P = 0.004) and dark-field scanning laser ophthalmoscopy ( P = 0.0015). No difference in brightness of the CNV region between nonexudative and active CNV was found based on fundus autofluorescence ( P = 0.44). The vessel density of nonexudative CNV was statistically significantly higher than that of active CNV with a median value of 64.5% (95% confidential interval [CI] 53.4-79.0%) and 55.3% (95% CI 52.2-60.0%), respectively ( P = 0.05). CONCLUSION: Multimodal imaging revealed substantial alteration of the retinal pigment epithelium in active CNV but not in nonexudative CNV which correlates with the higher vessel density of nonexudative CNV.

Successive short- and long-range magnetic ordering in rosiaite-type CoGeTeO6 prepared by ion-exchange reaction.

The missing member of the rosiaite family, CoGeTeO6, was synthesized by mild ion-exchange reactions and characterized by magnetization M and specific heat Cp measurements. It exhibits a successive short- and long-range magnetic ordering at Tshort-range ≈ 45 K and TN = 15 K, respectively. Based on these measurements, the magnetic H-T phase diagram was established, showing two antiferromagnetic phases separated by a spin-flop transition. The reason why the pronounced short-range correlation occurs at a temperature nearly three times higher than TN was found by evaluating the Co-O⋯O-Co exchange interactions using energy-mapping analysis. Although CoGeTeO6 has a layered structure, its magnetic structure consists of three-dimensional antiferromagnetic lattices made up of rhombic boxes of Co2+ ions. The experimental data obtained at high temperatures agree well with the computational results by treating the Co2+ ions of CoGeTeO6 as S = 3/2 ions, but the heat capacity and magnetization data were obtained at low temperatures by treating the Co2+ ion as a Jeff = 1/2 ion.

Anhydrous copper tellurite disulfate Cu3TeO3(SO4)2 featuring the coexistence of spin singlets and a long-range antiferromagnetic order.

Anhydrous copper tellurite sulfate, Cu3TeO3(SO4)2, has been synthesized via vapor transport reactions in sealed silica glass ampoules. In measurements of magnetization M, magnetic susceptibility χ, specific heat Cp and X-band electron spin resonance, a long-range antiferromagnetic order at TN = 13 K and an H-T magnetic phase diagram have been established. One-third of Cu2+ ions were found to form magnetically silent dimers. A peak in dielectric permittivity ε, which accompanies the Néel order, allows considering Cu3TeO3(SO4)2 as a magnetoelectric multiferroic material of the second type. Density functional theory calculations provided estimations of leading exchange interaction parameters.

Correction to Stable Sulfuric Vapor Transport and Liquid-Sulfur Growth on Transition Metal Dichalcogenides.

[This corrects the article DOI: 10.1021/acs.cgd.2c01318.].

OPTICAL COHERENCE TOMOGRAPHY IMAGING OF RETINAL MACROPHAGE-LIKE CELLS IN PATIENTS WITH MULTIPLE EVANESCENT WHITE DOT SYNDROME.

PURPOSE: To analyze the changes of macrophage-like cells (MLCs) on the inner retinal surface associated with multiple evanescent white dot syndrome using optical coherence tomography. METHODS: Four eyes of four patients with multiple evanescent white dot syndrome were examined and followed with multimodal imaging, including optical coherence tomography angiography, to visualize MLC on en face structural projections. RESULTS: On en face structural optical coherence tomography angiography projection at presentation, all multiple evanescent white dot syndrome eyes showed a decrease of the nearest neighbor distance of MLC within the region of interest and an increase of MLC density in the perifovea compared with the fellow unaffected eye. Three eyes demonstrated protrusion of MLC into the vitreous. At 1 to 3 months of follow-up, nearest neighbor distance increased, and MLC density decreased to the level of the fellow unaffected eye along with regression of multiple evanescent white dot syndrome symptoms. CONCLUSION: Multiple evanescent white dot syndrome may be associated with increase of MLC population on the inner retinal surface, which can be tracked with clinical optical coherence tomography imaging.