Harvest graft substitute for soft tissue volume augmentation around existing implants: A randomized, controlled and blinded multicenter trial.

BACKGROUND: Using a single-blind, randomized, controlled, multicenter, practice-based clinical trial, a volume-stable collagen matrix (VCMX) was compared with connective tissue graft (CTG) for soft tissue augmentation around existing dental implants. METHODS: Sixty patients (31 VCMX and 31 CTG) were included. The primary outcome was a soft tissue thickness change 3 mm below the gingival margin (GM). Secondary outcomes included clinical measures, such as keratinized tissue widths (KTw), probing pocket depths, and pink esthetic scores, and patient-reported outcomes (PRO). RESULTS: There were no significant differences between test and control patient demographics or clinical measures throughout the 1-year study. VCMX "grafts" were by design larger than CTG, and surgery time was less (27% less, p = 0.0005). Three millimeters below the GM (primary endpoint), tissue thickness increase was noninferior for VCMX compared with CTG (0.93 ± 0.80 mm vs. 1.10 ± 0.51 mm, respectively), inferior (by 0.25 mm) at 1 mm, and noninferior at 5 mm. Postoperative pain was significantly less for VCMX patients (p < 0.0001), but all other PRO measures, including esthetics and satisfaction, improved similarly for both therapies. CONCLUSIONS: Given the inclusion criteria for this study, namely soft tissue augmentation around existing implants with some evidence of KTw and minimal recession, VCMX provided soft tissue thickness and volume increases similar (noninferior) to CTG. Clinical measures and PRO were similar between therapies-site sensitivity and esthetics improved similarly for both therapies-but surgery time and pain following surgery were significantly less for VCMX.

Consumer perception, knowledge, and uses of cannabidiol.

Introduction: The legalization of cannabidiol (CBD) across the United States, in varying degrees, has made CBD easily accessible to consumers for complementary and medical purposes. However, there is a paucity of scientific evidence on the benefits and risks of commercially available CBD. In the literature, 2 studies have gathered consumer perceptions and attitudes on cannabis products, specifically CBD, using survey-based questionnaires. This study aimed to build on the aforementioned studies in obtaining consumer perception and knowledge of CBD products using a national survey-based questionnaire. Methods: Respondents were recruited through an anonymous, nationwide, online survey administered through Qualtrics in the United States from March 28 to April 30, 2021. The survey consisted of demographics, perceived efficacy and safety of CBD, and resources to obtain CBD information. The survey responses were reported using descriptive statistics along with median and interquartile range for the Likert portion. Results: A total of 1158 respondents accessed the survey. The median age was 43 and 50% of respondents were female. The uses for CBD included neurological disorders, pulmonary conditions, gastrointestinal disorders, and chronic pain. The most commonly reported safety concern related to taking CBD was anxiety. Participants agreed that CBD is safe when used responsibly for medical use, and social media was the main source used to obtain information about CBD. Discussion: Respondents who used CBD for a condition thought it was helpful; however, most of the adverse effects were rated as moderate to severe, requiring medical attention from a health care professional, hospital, or emergency room visit.

A comparison of Er,Cr:YSGG laser to minimally invasive surgical technique in the treatment of intrabony defects: Twelve-month results of a multicenter, randomized, controlled study.

BACKGROUND: The purpose of this publication is to report on the 12-month clinical and radiographic results comparing the surgical use of the Er,Cr:YSGG laser (ERL) and minimally invasive surgical technique (MIST) for the treatment of intrabony defects in subjects with generalized periodontitis stage III, grade B. METHODS: Fifty-three adult subjects (29 females and 24 males; 19-73 years) with 79 intrabony defects were randomized following scaling and root planing (SRP) to receive ERL monotherapy (n = 27) or MIST (n = 26). Fifty subjects completed the study. Recession (REC), probing depth (PD), clinical attachment level (CAL), treatment time, and standardized radiographs were assessed and compared for each treatment group. Clinical measurements were recorded at baseline, 4-6 weeks following SRP, and 6 and 12 months following surgical therapy. Radiographic results were compared to baseline at 6 and 12 months following surgical therapy. RESULTS: The following primary and secondary outcome variables were non-inferior with the following margins: CAL with a non-inferiority margin of 0.7 mm (p = 0.05), PD with a non-inferiority margin of 0.7 mm (p = 0.05), and REC with a non-inferiority margin of 0.4 mm (p = 0.05). Standardized radiographs suggest similar bone fill of 1.14 ± 1.73 mm for MIST and 1.12 ± 1.52 mm for ERL. CONCLUSIONS: This is the first multicenter, randomized, masked, and controlled study demonstrating the ERL is not inferior to MIST at 12 months in terms of clinical outcomes and similar to MIST in terms of radiographic bone fill for the surgical treatment of intrabony defects.

Tiny Sc Allows the Chains to Rattle: Impact of Lu and Y Doping on the Charge-Density Wave in ScV6Sn6.

The kagome metals display an intriguing variety of electronic and magnetic phases arising from the connectivity of atoms on a kagome lattice. A growing number of these materials with vanadium-kagome nets host charge-density waves (CDWs) at low temperatures, including ScV6Sn6, CsV3Sb5, and V3Sb2. Curiously, only the Sc version of the RV6Sn6 materials with a HfFe6Ge6-type structure hosts a CDW (R = Gd-Lu, Y, Sc). In this study, we investigate the role of rare earth size in CDW formation in the RV6Sn6 compounds. Magnetization measurements on our single crystals of (Sc,Lu)V6Sn6 and (Sc,Y)V6Sn6 establish that the CDW is suppressed by substituting Sc by larger Lu or Y. Single-crystal X-ray diffraction reveals that compressible Sn-Sn bonds accommodate the larger rare earth atoms within loosely packed R-Sn-Sn chains without significantly expanding the lattice. We propose that Sc provides extra room in these chains crucial to CDW formation in ScV6Sn6. Our rattling chain model explains why both physical pressure and substitution by larger rare earth atoms hinder CDW formation despite opposite impacts on lattice size. We emphasize the cooperative effect of pressure and rare earth size by demonstrating that pressure further suppresses the CDW in a Lu-doped ScV6Sn6 crystal. Our model not only addresses why a CDW only forms in the RV6Sn6 materials with tiny Sc but also advances our understanding of why unusual CDWs form in the kagome metals.

Can patients detect peri­implant mucosal inflammation? Results from a multicentre randomized trial.

PURPOSE: The objective of this study was to compare patient-reported outcomes (PROs) of peri­implant soft tissue inflammation and aesthetics around single-tooth implants in the anterior maxillary region with three different implant-abutment interface designs. METHODS: Participants were randomized to one of three different types of implant-abutment interface designs [Conical (CI), flat-to-flat (FI), and Platform Switched (PS)]. Implants and provisional crowns with prefabricated titanium abutments were placed 5 months following extraction and/or ridge augmentation. Permanent ceramic crowns with zirconia abutments were placed after 12 weeks. To assess PROs, appearance and inflammation questionnaires were completed from provisional crown placement to the 3-year follow-up. RESULTS: Tooth appearance at the 3-year follow-up revealed a difference amongst CI, FI and PS implants (p=0.049; Kruskal-Wallis test). PS was rated better than FI (p=0.047) at 1 year for appearance of soft-tissue and satisfaction with colour. There were no differences for self-consciousness, smile and pain/discomfort while eating/hard food items. CONCLUSIONS: Although participants tended to rate the health of mucosa around PS implants as slighty better than the other two implant systems, the differences were minimal and inconsistent. Thus, patient satisfaction in terms self-perceived gingival health and esthetics was high for all 3 systems tested, suggesting that patients are unable to detect mucosal inflammation. CLINICAL SIGNIFICANCE: Patients find it difficult to perceive mucosal inflammation; hence, it is recommended that patients attend implant follow-up visits, even if they do not perceive inflammation. The study suggests that there is a relationship between the PROs and the clinical outcomes of tested implants.

Tumor-specific intracellular delivery: peptide-guided transport of a catalytic toxin.

There continues to be a need for cancer-specific ligands that can deliver a wide variety of therapeutic cargos. Ligands demonstrating both tumor-specificity and the ability to mediate efficient cellular uptake of a therapeutic are critical to expand targeted therapies. We previously reported the selection of a peptide from a peptide library using a non-small cell lung cancer (NSCLC) cell line as the target. Here we optimize our lead peptide by a series of chemical modifications including truncations, N-terminal capping, and changes in valency. The resultant 10 amino acid peptide has an affinity of <40 nM on four different NSCLC cell lines as a monomer and is stable in human serum for >48 h. The peptide rapidly internalizes upon cell binding and traffics to the lysosome. The peptide homes to a tumor in an animal model and is retained up to 72 h. Importantly, we demonstrate that the peptide can deliver the cytotoxic protein saporin specifically to cancer cells in vitro and in vivo, resulting in an effective anticancer agent.

Above-Room-Temperature Ferromagnetism in Thin van der Waals Flakes of Cobalt-Substituted Fe5GeTe2.

Two-dimensional (2D) magnetic van der Waals materials provide a powerful platform for studying the fundamental physics of low-dimensional magnetism, engineering novel magnetic phases, and enabling thin and highly tunable spintronic devices. To realize high-quality and practical devices for such applications, there is a critical need for robust 2D magnets with ordering temperatures above room temperature that can be created via exfoliation. Here, the study of exfoliated flakes of cobalt-substituted Fe5GeTe2 (CFGT) exhibiting magnetism above room temperature is reported. Via quantum magnetic imaging with nitrogen-vacancy centers in diamond, ferromagnetism at room temperature was observed in CFGT flakes as thin as 16 nm corresponding to 16 layers. This result expands the portfolio of thin room-temperature 2D magnet flakes exfoliated from robust single crystals that reach a thickness regime relevant to practical spintronic applications. The Curie temperature Tc of CFGT ranges from 310 K in the thinnest flake studied to 328 K in the bulk. To investigate the prospect of high-temperature monolayer ferromagnetism, Monte Carlo calculations were performed, which predicted a high value of Tc of ∼270 K in CFGT monolayers. Pathways toward further enhancing monolayer Tc are discussed. These results support CFGT as a promising platform for realizing high-quality room-temperature 2D magnet devices.

Diagnostic reproducibility of the 2018 Classification of Gingival Recession Defects and Gingival Phenotype: A multicenter inter- and intra-examiner agreement study.

BACKGROUND: The aim of this study was to investigate the inter- and intra-examiner agreement among international experts on the diagnosis of gingival recession defects using the 2018 Classification of Gingival Recession Defects and Gingival Phenotype as proposed in the 2017 World Workshop. METHODS: Standardized intraoral photographs from 28 gingival recession defects were evaluated twice by 16 expert periodontists. Recession type (RT), recession depth (RD), keratinized tissue width (KTW), gingival thickness (GT), detectability of the cemento-enamel junction (CEJ), and presence of root steps (RS) were recorded and used for the analysis. Intra- and inter-examiner agreements were calculated for individual variables and for the overall classification. Intraclass correlation coefficient with 95% CI was used for RD and KTW; Kappa with 95% CI was used for GT, CEJ, and RS; quadratic weighted Kappa with 95% CI was used for RT. RESULTS: Overall intra- and inter-examiner agreements were highest for KTW (0.95 and 0.90), lowest for GT (0.75 and 0.41), with the other variables in between (RD: 0.93 and 0.68, RS: 0.87 and 0.65, RT: 0.79 and 0.64, CEJ: 0.75 and 0.57). Overall intra- and inter-examiner agreements for the matrix were 62% and 28%, respectively. Significant effects existed between one variable's measurement and other variables' agreements. CONCLUSIONS: The 2018 Classification of Gingival Recession Defects and Gingival Phenotype is clinically reproducible within the examiners, and when the variables forming the matrix are analyzed individually. The between-examiner agreement for the complete matrix showed lower reproducibility. The agreement was highest for KTW and RD, and least for GT.

Charge Density Wave in Kagome Lattice Intermetallic ScV_{6}Sn_{6}.

Materials hosting kagome lattices have drawn interest for the diverse magnetic and electronic states generated by geometric frustration. In the AV_{3}Sb_{5} compounds (A=K, Rb, Cs), stacked vanadium kagome layers give rise to unusual charge density waves (CDW) and superconductivity. Here we report single-crystal growth and characterization of ScV_{6}Sn_{6}, a hexagonal HfFe_{6}Ge_{6}-type compound that shares this structural motif. We identify a first-order phase transition at 92 K. Single crystal x-ray and neutron diffraction reveal a charge density wave modulation of the atomic lattice below this temperature. This is a distinctly different structural mode than that observed in the AV_{3}Sb_{5} compounds, but both modes have been anticipated in kagome metals. The diverse HfFe_{6}Ge_{6} family offers more opportunities to tune ScV_{6}Sn_{6} and explore density wave order in kagome lattice materials.

Gate-Tunable Proximity Effects in Graphene on Layered Magnetic Insulators.

The extreme versatility of van der Waals materials originates from their ability to exhibit new electronic properties when assembled in close proximity to dissimilar crystals. For example, although graphene is inherently nonmagnetic, recent work has reported a magnetic proximity effect in graphene interfaced with magnetic substrates, potentially enabling a pathway toward achieving a high-temperature quantum anomalous Hall effect. Here, we investigate heterostructures of graphene and chromium trihalide magnetic insulators (CrI3, CrBr3, and CrCl3). Surprisingly, we are unable to detect a magnetic exchange field in the graphene but instead discover proximity effects featuring unprecedented gate tunability. The graphene becomes highly hole-doped due to charge transfer from the neighboring magnetic insulator and further exhibits a variety of atypical gate-dependent transport features. The charge transfer can additionally be altered upon switching the magnetic states of the nearest CrI3 layers. Our results provide a roadmap for exploiting proximity effects arising in graphene coupled to magnetic insulators.

A Prospective, Randomized, Controlled, Multicenter Evaluation of Extraction Socket Management Comparing a Wound Dressing and a Soft Tissue Substitute.

Postextraction bone grafting and implant placement help preserve alveolar bone volume. Collagen wound dressings and soft tissue graft substitutes may help protect extraction socket bone grafts and provide better gingival contours. This randomized, controlled, multicenter, and double-blinded study was conducted to compare a control (wound dressing) and a test (soft tissue graft) substitute in nearly intact extraction sockets. Both test and control sockets were grafted with a xenogeneic bone graft. Graft containment, extraction socket soft tissue gap closure, gingival contour, and gingival thickness were examined over 16 weeks, at which time implants were placed. Healing was uneventful for both groups, and there was no significant difference (P < .05) between the times required to close the extraction socket soft tissue gap (~80% of sites closed by 8 weeks). Bone grafts were covered and contained longer in the test group (~4 weeks vs ~2 weeks), with less contour disruption out to 4 weeks; however, at implant placement, soft tissue contours in both groups were comparable, and soft tissue thicknesses were not significantly different.

A Minimally Invasive, Accurate, and Efficient Technique for Intrathymic Injection in Mice.

Intrathymic injection in mouse models is an important technique for studying thymic and immune function, including genetic and acquired T cell disorders. This requires methods for the direct deposition of reagents and/or cells into the thymus of living mice. Traditional methods of intrathymic injection include thoracic surgery or minimally invasive percutaneous blind injections, both of which have significant limitations. Ultra-high frequency ultrasound imaging devices have made image-guided percutaneous injections possible in mice, greatly improving the injection accuracy of the percutaneous injection approach and enabling the injection of smaller targets. However, image-guided injections rely on the utilization of an integrated rail system, making this a rigid and time-consuming procedure. A unique, safe, and efficient method for percutaneous intrathymic injections in mice is presented here, eliminating reliance on the rail system for injections. The technique relies on using a high-resolution micro-ultrasound unit to image the mouse thymus noninvasively. Using a free-hand technique, a radiologist can place a needle tip directly into the mouse thymus under sonographic guidance. Mice are cleaned and anesthetized before imaging. For an experienced radiologist adept at ultrasound-guided procedures, the learning period for the stated technique is quite short, typically within one session. The method has a low morbidity and mortality rate for the mice and is much faster than current mechanically assisted techniques for percutaneous injection. It allows the investigator to efficiently perform precise and reliable percutaneous injections of thymuses of any size (including very small organs such as the thymus of aged or immunodeficient mice) with minimal stress on the animal. This method enables the injection of individual lobes if desired and facilities large-scale experiments due to the time-saving nature of the procedure.

Revealing Fast Cu-Ion Transport and Enhanced Conductivity at the CuInP2S6-In4/3P2S6 Heterointerface.

Van der Waals layered ferroelectrics, such as CuInP2S6 (CIPS), offer a versatile platform for miniaturization of ferroelectric device technologies. Control of the targeted composition and kinetics of CIPS synthesis enables the formation of stable self-assembled heterostructures of ferroelectric CIPS and nonferroelectric In4/3P2S6 (IPS). Here, we use quantitative scanning probe microscopy methods combined with density functional theory (DFT) to explore in detail the nanoscale variability in dynamic functional properties of the CIPS-IPS heterostructure. We report evidence of fast ionic transport which mediates an appreciable out-of-plane electromechanical response of the CIPS surface in the paraelectric phase. Further, we map the nanoscale dielectric and ionic conductivity properties as we thermally stimulate the ferroelectric-paraelectric phase transition, recovering the local dielectric behavior during this phase transition. Finally, aided by DFT, we reveal a substantial and tunable conductivity enhancement at the CIPS/IPS interface, indicating the possibility of engineering its interfacial properties for next generation device applications.

Hidden Local Symmetry Breaking in a Kagome-Lattice Magnetic Weyl Semimetal.

Exploring the relationship between intriguing physical properties and structural complexity is a central topic in studying modern functional materials. Co3Sn2S2, a newly discovered kagome-lattice magnetic Weyl semimetal, has triggered intense interest owing to the intimate coupling between topological semimetallic states and peculiar magnetic properties. However, the origins of the magnetic phase separation and spin glass state below TC in this ordered compound are two unresolved yet important puzzles in understanding its magnetism. Here, we report the discovery of local symmetry breaking surprisingly co-emerges with the onset of ferromagnetic order in Co3Sn2S2, by a combined use of neutron total scattering and half-polarized neutron diffraction. An anisotropic distortion of the cobalt kagome lattice at the atomic/nano level is also found, with distinct distortion directions among the two Co1 and four Co2 atoms. The mismatch of local and average symmetries occurs below TC, indicating that Co3Sn2S2 evolves to an intrinsically lattice disordered system when the ferromagnetic order is established. The local symmetry breaking with intrinsic lattice disorder provides new understanding of the puzzling magnetic properties. Our density functional theory (DFT) calculation indicates that the local symmetry breaking is expected to reorient local ferromagnetic moments, unveiling the existence of the ferromagnetic instability associated with the lattice instability. Furthermore, DFT calculation unveils that the local symmetry breaking could affect the Weyl property by breaking the mirror plane. Our findings highlight the fundamentally important role that the local symmetry breaking plays in advancing our understanding on the magnetic and topological properties in Co3Sn2S2, which may draw attention to explore the overlooked local symmetry breaking in Co3Sn2S2, its derivatives and more broadly in other topological Dirac/Weyl semimetals and kagome-lattice magnets.

Spiral Spin Liquid on a Honeycomb Lattice.

Spiral spin liquids are correlated paramagnetic states with degenerate propagation vectors forming a continuous ring or surface in reciprocal space. On the honeycomb lattice, spiral spin liquids present a novel route to realize emergent fracton excitations, quantum spin liquids, and topological spin textures, yet experimental realizations remain elusive. Here, using neutron scattering, we show that a spiral spin liquid is realized in the van der Waals honeycomb magnet FeCl_{3}. A continuous ring of scattering is directly observed, which indicates the emergence of an approximate U(1) symmetry in momentum space. Our work demonstrates that spiral spin liquids can be achieved in two-dimensional systems and provides a promising platform to study the fracton physics in spiral spin liquids.

One-year clinical results of restorations using a novel self-adhesive resin-based bulk-fill restorative.

This prospective study assessed the dual-curing self-adhesive bulk-fill restorative Surefil one. The restorations were placed and reviewed by dental practitioners who are members of a practice-based research network in the United States. Seven practitioners filled 60 cavities (20 class I, 19 class II and 21 class V) in 41 patients with Surefil one without adhesive, according to the manufacturer's instructions. The restorations were evaluated using modified USPHS criteria at baseline, 3 months, and 1 year. Patients were also contacted to report postoperative hypersensitivity one to four weeks after placement. The only patient that showed moderate hypersensitivity after 1 year had previously reported symptoms that were unlikely associated to the class I molar restoration. One class II restoration in a fractured maxillary molar was partially lost. The remaining restorations were found to be in clinically acceptable condition resulting in an annual failure rate of 2%. Color match showed the lowest number of acceptable scores (88%) revealing significant changes over time (P = 0.0002). No significant differences were found for the other criteria (P > 0.05). The novel self-adhesive bulk-fill restorative showed clinically acceptable results in stress-bearing class I and II as well as non-retentive class V cavities at 1-year recall.

Nanoscale Control of Polar Surface Phases in Layered van der Waals CuInP2S6.

Antiferroelectric (AFE) materials, in which alternating dipole moments cancel out to a zero net macroscopic polarization, can be used for high-density energy storage and memory applications. The AFE phase can exist in bulk CuInP2Se6, CuBiP2S6, and a few other transition-metal thiophosphates below 200 K. The required low temperature poses challenges for practical applications. In this work, we report the coexistence of ferrielectric (FE) states and a stable surface phase that does not show piezoelectric response ("zero-response phase") in bulk CuInP2S6 at room temperature. Using piezoresponse force microscopy (PFM) tomographic imaging together with density functional theory, we find that direct and alternating voltages can locally and stably convert FE to zero-response phases and vice versa. While PFM loops show pinched hystereses reminiscent of antiferroelectricity, PFM tomography reveals that the zero-response areas form only on top of the FE phase in which the polarization vector is pointing up. Theoretical calculations suggest that the zero-response phase may correspond to AFE ordering where stacked CuInP2S6 layers have alternating polarization orientations thereby leading to a net-zero polarization. Consistent with experimental findings, theory predicts that the FE polarization pointing down is robust up to the top surface, whereas FE polarization pointing up energetically favors the formation of an AFE surface layer, whose thickness is likely to be sensitive to local strains. AFE order is likely to be more robust against detrimental size effects than polar order, therefore providing additional opportunities to create multifunctional heterostructures with 2D electronic materials.

Efficacy of a harvest graft substitute for recession coverage and soft tissue volume augmentation: A randomized controlled trial.

BACKGROUND: The autogenous connective tissue graft (CTG) with coronally advanced flap (CTG+CAF) is the "gold standard" for recession defect coverage; however, researchers continue to pursue lower morbidity, more convenient and unlimited supply harvest graft substitutes, including those that could provide soft tissue volume augmentation. METHODS: A randomized, controlled, double-masked comparison of a volume-stable collagen matrix (VCMX) versus CTG was conducted at four clinical investigation sites. Single, contralateral, within patient matched-pair, RT1 recession defects were treated with VCMX+CAF (test) and CTG+CAF (control). The primary efficacy end point was percent root coverage at 6 months. Secondary efficacy end points included clinical measures such as soft tissue volume, attachment level, and keratinized tissue width. Patient-reported outcomes included measures such as discomfort, esthetics, and overall satisfaction; 6-month end point results were followed for 1 year. RESULTS: Thirty patients received control and test therapies, and all patients were available for follow-up measures. Average percent root coverage for CTG+CAF was 90.5% ± 14.87% versus 70.7% ± 28.26% for VCMX+CAF, P <0.0001. Both therapies produced significant soft tissue volume increases (84.8 ± 47.43 mm3 control versus 48.90 ± 35.58 mm3 test, P = 0.0006). The test, harvest graft substitute produced less postoperative pain and was preferred by patients at the 6-month end point. All other end point measures were not significantly different. CONCLUSIONS: VCMX+CAF root coverage was inferior to CTG+CAF but produced less morbidity and was preferred by patients. Case/patient selection and surgical technique appear key to achieving successful results with the harvest graft alternative.

Direct visualization of magnetic domains and moiré magnetism in twisted 2D magnets.

Moiré superlattices of twisted nonmagnetic two-dimensional (2D) materials are highly controllable platforms for the engineering of exotic correlated and topological states. Here, we report emerging magnetic textures in small-angle twisted 2D magnet chromium triiodide (CrI3). Using single-spin quantum magnetometry, we directly visualized nanoscale magnetic domains and periodic patterns, a signature of moiré magnetism, and measured domain size and magnetization. In twisted bilayer CrI3, we observed the coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) domains with disorder-like spatial patterns. In twisted double-trilayer CrI3, AFM and FM domains with periodic patterns appear, which is in good agreement with the calculated spatial magnetic structures that arise from the local stacking-dependent interlayer exchange interactions in CrI3 moiré superlattices. Our results highlight magnetic moiré superlattices as a platform for exploring nanomagnetism.