Partnerzy

Streszczenie:
In this work, we successfully synthesized series of LiNi0.5Mn1.5O4 (LNMO) cathode materials with spinel structure by using a facile sol-gel method and then calcined at various temperature ranging from 600 to 1000 °C. The application of different calcination temperatures significantly influenced the surface morphology, stoichiometry and crystalline nature of the as-synthesized LNMO material. According to the results of physical characterizations, the LNMO materials calcined at various temperatures mainly revealed the stoichiometric disordered Fd-3m structure with a small amount of well-ordered P4332 phase. The structural analysis also exhibited that the control of the calcination temperature contributed to the higher crystalline nature. Moreover, the morphological investigations indicated that the increasing calcination temperatures caused the formation of large micron-sized LNMO material. In turn, the electrochemical evaluations revealed the impact of the calcination temperatures on enhancing the electrochemical performances of the LNMO electrode materials up to 900 °C. The LNMO electrode calcined at 900 °C exhibited an impressive initial discharge specific capacity of ca. 142 mAh g^−1 between 3.5 and 4.9 V vs. Li/Li+, and remarkably improved capacity retention of 97% over 50 cycles. Those excellent electrochemical properties were associated with the presence of the dominant Fd-3m phase over the P4332 phase. Additionally, the results of the corrosion and dissolution tests which were performed for all calcined LNMO materials in order to estimate the amount of manganese and nickel ions leached from them, proved that the micro-sized LNMO calcined at 900 °C was the most stable.

Słowa kluczowe:
spinel LiNi0.5Mn1.5O4, sol-gel synthesis, calcination temperature, cathode material, lithium-ion batteries

Streszczenie:
Accumulating data indicate that cancer stem cells contribute to tumor chemoresistance and their persistence alters clinical outcome. Our previous study has shown that ovarian cancer may be initiated by ovarian cancer initiating cells (OCIC) characterized by surface antigen CD44 and c-KIT (CD117). It has been experimentally demonstrated that a microRNA, namely miR-193a, targets c-KIT mRNA for degradation and could play a crucial role in ovarian cancer development. How miR-193a is regulated is poorly understood and the emerging picture is complex. To unravel this complexity, we propose a mathematical model to explore how estrogen-mediated up-regulation of another target of miR-193a, namely E2F6, can attenuate the function of miR-193a in two ways, one through a competition of E2F6 and c-KIT transcripts for miR-193a, and second by binding of E2F6 protein, in association with a polycomb complex, to the promoter of miR-193a to down-regulate its transcription. Our model predicts that this bimodal control increases the expression of c-KIT and that the second mode of epigenetic regulation is required to generate a switching behavior in c-KIT and E2F6 expressions. Additional analysis of the TCGA ovarian cancer dataset demonstrates that ovarian cancer patients with low expression of EZH2, a polycomb-group family protein, show positive correlation between E2F6 and c-KIT. We conjecture that a simultaneous EZH2 inhibition and anti-estrogen therapy can constitute an effective combined therapeutic strategy against ovarian cancer.

Słowa kluczowe:
Ovarian cancer, Messenger RNA, Epigenetics, DNA methylation, Estrogens, Gene expression, Cancer treatment, Carcinogenesis

Streszczenie:
Creep tests are carried out under tension, pure torsion, and combined tension and torsion at an elevated temperature of 523K for pure copper and 423K for an aluminium alloy. Different creep and rupture properties of the materials are observed throughout the deformation process under the different stress states. The effects of stress states on primary creep, secondary creep, the failure and lifetime of the materials are analysed. A new set of multiaxial mechanisms-based creep damage constitutive equations has been formulated on the basis of analysis of previous creep models. The proposed unified creep damage constitutive equations are determined using experimental data achieved for both materials at three effective stress levels. Creep tests for each stress level were carried out for three stress states. The comparison of experimental and computed effective creep strain curves is carried out for all the stress states and stress levels tested for both materials. In addition, it has been verified that the determined multi-stress-state creep damage constitutive equations can be used to predict the isochronous surfaces of the materials very precisely. To compare with conventional constitutive descriptions, a set of multiaxial constitutive equations is also determined for the experimental data of the two materials using the same optimisation techniques. The quality of the fittings is compared and further discussion is carried out for the stress-state variable x.