Extremely large magnetoresistance and high-density Dirac-like fermions in ZrB2

We report the detailed study on transport properties of ZrB2 single crystal, a predicted topological nodal-line semimetal. ZrB2 exhibits extremely large magnetoresistance as well as field-induced resistivity upturn and plateau. These behaviors can be well understood by the two-band model with the perfect electron - hole compensation and high carrier mobilities. More importantly, the electrons with small effective masses and nontrivial Berry phase have significantly high density when compared to those in known topological semimetals. It strongly suggests that ZrB2 hosts Dirac-like nodal-line fermions.Comment: 6 pages, 4 figure

Application and prospect of targeted therapy and immunotherapy in radioiodine-refractory differentiated thyroid cancer

Thyroid cancer (TC) is a common malignant tumor of the endocrine system, with differentiated TC (DTC) accounting for more than 90%. Most patients usually have a good overall prognosis after receiving radioactive iodine (RAI) treatment, however some patients’ lesions gradually lose the ability to take up iodine during treatment and become RAI-refractory DTC (RAIR-DTC), with a poor prognosis. For RAIR-DTC recurrence lesions or distant metastases that cannot be surgically removed, it was previously believed that there were limited treatment options. With a deeper understanding of the pathogenesis of RAIR-DTC and its changes at the biomolecular level, targeted therapy, immunotherapy and combined targeted and immune therapy have shown broad application prospects. Their effectiveness and safety have also been confirmed in human studies, bringing new hope for the treatment of RAIR-DTC. This article summarized the pathogenesis and development mechanism of RAIR-DTC, the current status of clinical research on targeted therapy and immunotherapy, and their main conclusions, in order to provide direction for future research. Multi-kinase inhibitors (MKIs) are the first-line therapy for advanced metastatic RAIR-DTC. Currently, Food and Drug Administration (FDA) of the United States has approved the following drugs for the treatment of RAIR-DTC: sorafenib, lenvatinib and cabozantinib. The first two of these have been approved by China National Medical Products Administration for RAIR-DTC treatment. In China, anlotinib and donafenib have also been approved for RAIR-DTC treatment. The efficacy and safety of these targeted therapies have been verified. Apatinib, an anti-angiogenesis inhibitor independently developed in China, is expected to be an effective salvage therapy for sorafenib-resistant lesions. Selective single-target inhibitors, with their more specific action targets, generally cause fewer side effects. For certain RAIR-DTC patients with specific mutation types, selective single-target inhibitors may be more effective. TC is generally considered to have a low tumor mutational burden (TMB), and its response to immunotherapy was once thought to be limited. Immune checkpoint inhibitors (ICIs), including pembrolizumab, durvalumab, atezolizumab and ipilimumab, have shown limited efficacy when used alone. However, when combined with targeted therapy, pembrolizumab can enhance the efficacy of targeted drugs, serving as a viable salvage therapy, potentially due to the “synergistic effect” of the combination therapy. It is crucial to determine the individual contributions of each therapy to tumor suppression and survival extension, especially when the sample size is limited. The design of reasonable controls becomes the key in these studies. Previous studies were obstructed by the unclear definition of RAIR-DTC, limited sample sizes and high heterogeneity. Therefore, prospective, multi-center, large-scale clinical trials are needed in the future. Additionally, it is essential to consider whether prolonged progression-free survival (PFS) after treatment can be translated into long-term survival benefits, and whether it improves the quality of life for patients. In conclusion, the treatment of RAIR-DTC still faces many challenges, we must continue to explore and address these issues in the future

Overexpression of p53 activated by small activating RNA suppresses the growth of human prostate cancer cells

Previous research has reported that a particular double-stranded RNA, named dsP53-285, has the capacity to induce expression of the tumor suppressor gene TP53 in chimpanzee cells by targeting its promoter. Usually, it is the wild-type p53 protein, rather than mutants, which exhibits potent cancer-inhibiting effects. In addition, nonhuman primates, such as chimpanzees, share almost identical genome sequences with humans. This prompted us to speculate whether dsP53-285 can trigger wild-type p53 protein expression in human prostate cancer (PCa) cells and consequently suppress cell growth. The human PCa cell lines LNCaP and DU145 were transfected with dsP53-285 for 72 hours. Compared with the dsControl and mock transfection groups, expression of both p53 messenger RNA and p53 protein was significantly enhanced after dsP53-285 transfection, and this enhancement was followed by upregulation of p21, which indirectly indicated that dsP53-285 induced wild-type p53 expression. Moreover, overexpression of wild-type p53 mediated by dsP53-285 downregulated the expression of Cyclin D1 and cyclin-dependent kinase 4/6, thereby inducing PCa cell cycle arrest in G0/G1 phase and then inhibiting cell proliferation and clonogenicity. More importantly, dsP53-285 suppressed PCa cells mainly by modulating wild-type p53 expression. In conclusion, our study provides evidence that dsP53-285 can significantly stimulate wild-type p53 expression in the human PCa cell lines LNCaP and DU145 and can exert potent antitumor effects

Enhanced Photocatalytic Activity of W-Doped and W-La-Codoped TiO 2

W-doped TiO2 and W-La-codoped TiO2 nanomaterials were successfully synthesized via the sol-gel method. The products were characterized by X-ray diffraction, UV-vis diffuse reflectance spectrophotometer, transmission electron microscopy, and X-ray photoelectron spectroscopy. The presence of W and La results in significant red shift of absorption edge for TiO2-based nanomaterials. The weight ratios of La and W in the composites play important roles in the absorption edge for TiO2-based nanomaterials. The photocatalytic activities of both W-doped TiO2 and W-La-codoped TiO2 photocatalysts for decolorization of methyl orange solution were evaluated under simulated sunlight irradiation. The results showed that both W-doped and W-La-codoped can effectively improve the photocatalytic behaviors of TiO2 nanomaterials ascribed to the improved photoinduced charge carriers separation, enhanced light absorption, and large surface area. Furthermore, W-La-codoped TiO2 exhibited higher photocatalytic activity than W-doped TiO2. Considering their high photocatalytic activity, the doped TiO2 nanomaterials could be applied in wastewater treatment and environmental purification

Imaging domain reversal in an ultrathin van der Waals ferromagnet

The recent isolation of two-dimensional van der Waals magnetic materials has uncovered rich physics that often differs from the magnetic behaviour of their bulk counterparts. However, the microscopic details of fundamental processes such as the initial magnetization or domain reversal, which govern the magnetic hysteresis, remain largely unknown in the ultrathin limit. Here we employ a widefield nitrogen-vacancy (NV) microscope to directly image these processes in few-layer flakes of magnetic semiconductor vanadium triiodide (VI$_3$). We observe complete and abrupt switching of most flakes at fields $H_c\approx0.5-1$ T (at 5 K) independent of thickness down to two atomic layers, with no intermediate partially-reversed state. The coercive field decreases as the temperature approaches the Curie temperature ($T_c\approx50$ K), however, the switching remains abrupt. We then image the initial magnetization process, which reveals thickness-dependent domain wall depinning fields well below $H_c$. These results point to ultrathin VI$_3$ being a nucleation-type hard ferromagnet, where the coercive field is set by the anisotropy-limited domain wall nucleation field. This work illustrates the power of widefield NV microscopy to investigate magnetization processes in van der Waals ferromagnets, which could be used to elucidate the origin of the hard ferromagnetic properties of other materials and explore field- and current-driven domain wall dynamics.Comment: includes S