3,558 research outputs found
Effects of constant and fluctuating temperatures on development and reproduction of Megoura crassicauda and Aphis craccivora (Hemiptera: Aphididae)
The influence of fluctuating temperatures on the development and fecundity of two aphids, Megoura crassicauda Mordvilko and Aphis craccivora Koch, were determined by collecting life table data at a constant temperature (22 °C) and two fluctuating temperatures (22 ± 3 °C and 22 ± 5 °C). The longevity of M. crassicauda decreased significantly at 22 ± 3 °C and 22 ± 5 °C, while there was no significant difference in the longevity of A. craccivora among the three treatments. The fecundity and intrinsic rate of increase (r) of M. crassicauda decreased significantly at both fluctuating temperatures, while A. craccivora showed the opposite tendency. These results showed that the fluctuating temperatures had negative impacts on the life history traits of M. crassicauda, but were beneficial for A. craccivora. Data obtained under constant temperatures may not reveal accurately enough the biotic responses of pests in the field
Robust Sandwiched B/TM/B Structures by Metal Intercalating into Bilayer Borophene Leading to Excellent Hydrogen Evolution Reaction
Bilayer borophene, very recently synthesized on Ag and Cu, possesses
extremely flat large surface and excellent conductivity. Besides, the van der
Waals gap of bilayer borophene can be intercalated by metal atoms, thereby
tailoring the properties of bilayer borophene. Herein, we propose that
sandwiched B/TM/B (TM=Co, Ni, Cu, Pd) could be a new 2D formation by transiton
metal atoms intercalated into bilayer borophene network, it is quiet robust
with both energetic, structural and thermal stability, and exhibits heat
resistance of at least 1300 K. Besides, it is novel platform for
electrocatalytic hydrogen evolution reaction (HER). The interecalation metal
atom serves as single-atomic catalyst, which acting the nonmetal boron layers.
Beyond that, the transtion metal is protected by outside boron layers from
being corroded by acidic/alkaline solution. B/Cux/B, B/Pdx/B and B/Alx/B with
different metal coverage exhibit defect-independent extremely low HER free
energy in the range of -0.162 ~ 0.179 eV, -0.134 ~ 0.183 eV and -0.082 ~ 0.086
eV which are comparable to noble metal Pt. Combining excellent conduction, high
structural and thermal stability, low resistance to intercalated behaviour,
effortless water splitting process, excellent defect-independent catalytic
performance, cheapness and abundance of raw materials, free of corrodation, 2D
sandwiched B/TM/B (TM=Co, Ni, Cu, Pd) is believed to promising for
electrocatalytic HER applications
The drug-resistance to gefitinib in PTEN low expression cancer cells is reversed by irradiation in vitro
<p>Abstract</p> <p>Background</p> <p>Despite of the recent success of EGFR inhibitory agents, the primary drug-resistant becomes a major challenge for EGFR inhibitor therapies. PTEN gene is an important positive regulatory factor for response to EGFR inhibitor therapy. Low-expression of PTEN is clearly one of the important reasons why tumor cells resisted to tyrosine kinase inhibitors.</p> <p>Methods</p> <p>To investigate the drug-resistance reversal to gefitinb and the mechanism in PTEN low expression cells which radiated with X-rays in vitro, We demonstrated that H-157 lung cancer cells (low-expression of PTEN but phospho-EGFR overexpressed tumor cells) exposed to X-rays. The PTEN expressions and radiosensitizing effects of tyrosine kinase inhibitor before and after irradiation were observed. The cell-survival rates were evaluated by colony-forming assays. The cell apoptosis was investigated using FCM. The expressions of phospho-EGFR and PTEN were determined by Western blot analysis.</p> <p>Results</p> <p>The results showed that the PTEN expressions were significantly enhanced by X-rays. Moreover, the cell growth curve and survival curve were down-regulated in the gefitinib-treated groups after irradiation. Meanwhile, the radiation-induced apoptosis of tumor cells was increased by inhibition of the EGFR through up-regulation of PTEN.</p> <p>Conclusion</p> <p>These results suggested that PTEN gene is an important regulator on TKI inhibition, and the resistance to tyrosine kinase inhibitors might be reversed by irradiation in PTEN low expression cancer cells.</p
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