RESUMEN
Topological insulators exhibit great potential in the fields of electronics and semiconductors for their gapless surface states. Intriguingly, most topological insulators are possibly excellent microwave-absorbing materials because of easy adjustment of electrical transport based on conducting surface states in the nanostructure. Herein, topological insulator Bi2Te3 nanosheets are synthesized by a simple solvothermal method. The material demonstrates a unique dielectric behavior based on conducting surface states, resulting in excellent microwave-absorbing performance. Benefiting from the outstanding impedance matching, Bi2Te3 nanosheets exhibit an ultrathin microwave absorption with the qualified frequency bandwidth of 3.0 GHz at only 0.77 mm thickness, which is thinner than other absorbers in reported references. Moreover, a strong reflection loss of -41 dB at 0.8 mm is achieved. The result provides a new approach for developing ultrathin microwave absorption materials at the submillimeter scale.
RESUMEN
α-SnSe is one of the most promising thermoelectric materials with low thermal conductivity and a high power factor. Since the thermoelectric properties of a material have a strong dependence on its crystal structure, we study the energetic and thermoelectric properties of four new monolayer phases of SnSe (ß, γ, δ and ε) together with α-SnSe using the ab initio density functional theory method. The calculated electronic structures show that all five phases are semiconductors with different band gaps. The α, ß, γ, and δ phases have an indirect band gap with the hybridization of sp2 orbitals, whereas the ε phase has a direct band with the hybridization of sp3 orbitals. The thermoelectric transport properties and coefficients are obtained from the electronic structure using semi-classical Boltzmann theory, and the results indicate that the four new phases of SnSe (ß, γ, δ and ε) all have better thermoelectric properties compared with the reported α phase. The predicted ZT value for the ß-SnSe phase is 2.06 at 300 K, suggesting that it has great potential for novel thermoelectric applications.
RESUMEN
Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.
RESUMEN
BACKGROUND: This analysis was conducted to evaluate the efficacy and safety of cisplatin based chemotherapy for treating patients with cutaneous squamous cell carcinoma. METHODS: Clinical studies evaluating the efficacy and safety of cisplatin based regimens on response and safety for patients with cutaneous squamous cell carcinoma were identified using a predefined search strategy. Pooled response rates (RR) of treatment were calculated. RESULTS: In cisplatin based regimens, 4 clinical studies which including 50 patients with advanced cutaneous squamous cell carcinoma were considered eligible for inclusion. Regimens included cisplatin, doxorubicin, or vindesine. Pooled analysis suggested that, in all patients, the pooled RR was 60% (30/50) in cisplatin based regimens. Nausea and vomiting were the main side effects. No grade III or IV renal or liver toxicity were observed. No treatment related death occurred with the cisplatin based treatments. CONCLUSION: Evidence based analysis suggests that cisplatin based regimens are associated with a good response rate and acceptable toxicity for treating patients with cutaneous squamous cell carcinoma.