The observation of quantum fluctuations in a kagome Heisenberg antiferromagnet

The search for the experimental evidence of quantum spin liquid (QSL) states is critical but extremely challenging, as the quenched interaction randomness introduced by structural imperfection is usually inevitable in real materials. YCu$_3$(OH)$_{6.5}$Br$_{2.5}$ (YCOB) is a spin-1/2 kagome Heisenberg antiferromagnet (KHA) with strong coupling of $\langle J_1\rangle\sim$ 51 K but without conventional magnetic freezing down to 50 mK $\sim$ 0.001$\langle J_1\rangle$. Here, we report a Br nuclear magnetic resonance (NMR) study of the local spin susceptibility and dynamics on the single crystal of YCOB. The temperature dependence of NMR main-line shifts and broadening can be well understood within the frame of the KHA model with randomly distributed hexagons of alternate exchanges, compatible with the formation of a randomness-induced QSL state at low temperatures. The in-plane spin fluctuations as measured by the spin-lattice relaxation rates ($1/T_1$) exhibit a weak temperature dependence down to $T$ $\sim$ 0.03$\langle J_1\rangle$. Our results demonstrate that the majority of spins remain highly fluctuating at low temperatures despite the quenched disorder in YCOB.Comment: NMR work on YCu3(OH)6.5Br2.5, accepted in Communications Physic

Long term survival following cryoablation with adjuvant Toripalimab for anorectal malignant melanoma: a case report

BackgroundAnorectal malignant melanoma is a rare subtype of melanoma with a poor prognosis. Despite this, some patients decline Miles’ operation due to the sigmoid colostomies that follow abdominoperineal resections in cases of anorectal malignant melanoma.Case reportWe report the case of an 80-year-old woman diagnosed with anorectal malignant melanoma who underwent cryosurgery accompanied by adjuvant PD-1 therapy to maintain anal sphincter function. The results indicated that we successfully achieved the goal of sphincter preservation and therapeutic efficacy. The patient derived significant benefits from the cryoablation treatment.ConclusionsUltrasound-guided trans-anal cryoablation, when combined with adjuvant PD-1 therapy, offers a novel treatment approach for patients with anorectal malignant melanoma. Our results have confirmed the advantages of this treatment regimen, particularly for those desiring to retain anal sphincter function. Further studies are required to substantiate the efficacy of ultrasound-guided trans-anal cryoablation with adjuvant Toripalimab and to elucidate its underlying mechanisms

Unraveling plant adaptation to nitrogen limitation from enzyme stoichiometry aspect in Karst soils: a case study of Rhododendron Pudingense

Enzyme stoichiometry can reflect the resource limitation of soil microbial metabolism, and research on the relationships between plants and resource limitation in Karst Microhabitats is scarcely investigated. To clarify the extracellular enzyme stoichiometry characteristics in soil across different karst microhabitats and how the Rhododendron pudingense adapts to nutrient restrictions, plot investigation experiments were set up in Zhenning County, Qinglong County, and Wangmo County of Guizhou Province which included total three karst microhabitats, i.e., soil surface (SS), rock gully (RG), and rock surface (RS), by analyzing he rhizosphere soil nutrient, extracellular enzyme activity, and nutrient content of R. pudingense. The findings indicated that all karst microenvironments experienced varying levels of nitrogen (N) limitation, with the order of N limitation being as follows: SS > RG > RS. Notably, there were significant discrepancies in N content among different plant organs (p< 0.05), with the sequence of N content as follows: leaf > stem > root. However, no significant differences were observed in nutrient content within the same organ across different microenvironments (p > 0.05). A noteworthy discovery was the significant allometric growth relationship between C-P in various organs (p< 0.05), while roots and stems exhibited a significant allometric growth relationship between N-P (p< 0.05). The study highlighted the substantial impact of Total Nitrogen (TN) and N-acquiring enzymes (NAE) on nutrient allocation within the components of R. pudingense. Overall, the research demonstrated that N was the primary limiting factor in the study area’s soil, and R. pudingense’s nutrient allocation strategy was closely associated with N limitations in the karst microenvironment. Specifically, the plant prioritized allocating its limited N resources to its leaves, ensuring its survival. This investigation provided valuable insights into how plants adapt to nutrient restrictions and offered a deeper understanding of soil-plant interactions in karst ecosystems

A giant glitch from the magnetar SGR J1935+2154 before FRB 200428

Fast radio bursts (FRBs) are short pulses observed in radio frequencies usually originating from cosmological distances. The discovery of FRB 200428 and its X-ray counterpart from the Galactic magnetar SGR J1935+2154 suggests that at least some FRBs can be generated by magnetars. However, the majority of X-ray bursts from magnetars are not associated with radio emission. The fact that only in rare cases can an FRB be generated raises the question regarding the special triggering mechanism of FRBs. Here we report a giant glitch from SGR J1935+2154, which occurred approximately $3.1\pm2.5$\,day before FRB 200428, with $\Delta\nu=19.8\pm1.4$ {\rm $\mu$Hz} and $\Delta\dot{\nu}=6.3\pm1.1$\,pHz s$^{-1}$. The corresponding spin-down power change rate $\Delta\dot\nu/\dot\nu$ is among the largest in all the detected pulsar glitches. The glitch contains a delayed spin-up process that is only detected in the Crab pulsar and the magnetar 1E 2259+586, a large persistent offset of the spin-down rate, and a recovery component which is about one order of magnitude smaller than the persistent one. The temporal coincidence between the glitch and FRB 200428 suggests a physical connection between the two. The internally triggered giant glitch of the magnetar likely altered the magnetosphere structure dramatically in favour of FRB generation, which subsequently triggered many X-ray bursts and eventually FRB 200428 through additional crustal cracking and Alfv\'en wave excitation and propagation

Biomechanical Effects of Two forms of PGF2α on ex-vivo Rabbit Cornea.

PURPOSE:To investigate the biomechanical effects of two synthetic prostaglandin F2α analogues (PGF2α), namely Travoprost and Tafluprost, on the ex-vivo rabbit cornea. MATERIALS AND METHODS:96 eyes of 48 Japanese white rabbits were divided into 3 equal groups randomly; the Travoprost treated group (Tra), the Tafluprost treated group (Taf) and the control group (Co). Eyes in Tra and Taf groups were preserved in storage medium for 10 days with 1:10 Travoprost and Tafluprost diluents, respectively; while the Co eyes were preserved in a similar but PGF2α-free medium. 24 corneas of each group were tested under inflation conditions with up to 30 mmHg posterior pressure. The pressure-deformation data obtained experimentally were used in an inverse analysis process to derive the stress-strain behavior of the tissue, using which the tangent modulus, a direct measure of the tissue's material stiffness, was calculated. The remaining 8 specimens of each group were analyzed using electron microscopy for fibril diameter and interfibrillar spacing. RESULTS:Although the central corneal thickness increased significantly in the three groups after storage (p< 0.01), it was similar in all groups both before (p= 0.598) and after storage (p= 0.181). After treatment with Travoprost and Tafluprost, the corneas exhibited lower tangent modulus (by 29.2% and 29.8%, respectively at 6 kPa stress) and larger stromal interfibril spacing (by 21.9% and 23.6%) compared with the control group. There was no significant change in fibril diameter with either Travoprost or Tafluprost treatment (p= 0.769). CONCLUSIONS:The results demonstrated significant reductions in tangent modulus and increases in interfibrillar spacing, which were of similar magnitudes, with the application of two different forms of PGF2α