Enhanced Dielectric Properties of a Poly(dimethyl siloxane) Bimodal Network Percolative Composite with MXene.

Excellent comprehensive dielectric properties (including dielectric constant and loss) are essential for electromechanical transducers. This work introduced a bimodal network composite with poly(dimethyl siloxane) (PDMS) and delaminated Ti3C2Tx sheets (d-Ti3C2Tx) modified with hyperbranched polysiloxane (HPSi) (referred to as HPSi-d-Ti3C2Tx). Before the final cross-linking, HPSi-d-Ti3C2Tx, trapped with short-chain PDMS (CS-PDMS) and long-chain PDMS (CL-PDMS), was pre-reacted, which formed a distinct bimodal network structure. d-Ti3C2Tx/PDMS and HPSi-d-Ti3C2Tx/PDMS composites with different filler loadings were prepared, and their percolation thresholds (fc) were 1.32 and 1.43 vol %, respectively The dielectric constant of 1.40 vol % HPSi-d-Ti3C2Tx/PDMS is 23.7 at 102 Hz, which is 1.5 times that of 1.28 vol % d-Ti3C2Tx/PDMS and 8.5 times that of pure PDMS. Meanwhile, the dielectric loss of HPSi-d-Ti3C2Tx/PDMS composite is still relatively small (0.11 at 103 Hz). The origin of dielectric property optimization of the composite is attributed to the boundary capacitor model, the accumulated charges at the interfaces between the conductive filler and the insulating polymer matrix of the composite, and the distinct bimodal network structure.

[Effect of fasudil of on rat cardiomyocytes acutely exposed to omethoate].

OBJECTIVE: To investigate the effect of fasudil on in vitro cultured cardiomyocytes (CMs) exposed to omethoate and its possible mechanism. METHODS: Cardiomyocytes were isolated from male SD rats and were then cultured in DMEM conventionally. The CMs were divided into different groups based on the doses of omethoate and fasudil in culture media. After 3, 6, 12, and 24 h of culture, the survival rate of CMs in each group was measured, the CMs in the medium-dose omethoate and medium-dose fasudil groups were subject to shortening amplitude measurement , and the content of lactate dehydrogenase (LDH) in culture media and expression of Bcl-2 and Bax in CMs were measured. RESULTS: Compared with the normal control group, each omethoate group showed significantly lower survival rate of CMs, which was negatively correlated with the dose of omethoate (P < 0.01). Compared with the normal control group, the medium-dose omethoate and medium-dose fasudil groups showed significantly decreased shortening amplitudes of CMs at all time points (P < 0.01), and the shortening amplitudes of CMs were significantly higher in the medium-dose fasudil group than in the medium-dose omethoate group after 12 h and 24 h of culture (P < 0.01). The LDH level was significantly higher in the medium-dose omethoate and medium-dose fasudil groups than in the normal control group, and the medium-dose fasudil group showed significantly lower LDH level than the medium-dose omethoate group (P < 0.01). Compared with those in the normal control group, the Bcl-2 expression in the medium-dose omethoate and medium-dose fasudil groups was decreased significantly, and the Bax expression in the medium-dose omethoate group was increased significantly (P < 0.01). Compared with the medium-dose omethoate group, the medium-dose fasudil group had significantly increased Bcl-2 expression and significantly decreased Bax expression (P < 0.01). CONCLUSION: Fasudil can inhibit the abnormal expression of apoptosis regulatory proteins (Bcl-2 and Bax) induced by omethoate, which might be one of the factors that reduce the toxic effect of omethoate on CMs.

[Effect of methylene blue on traumatic shock in rabbits].

OBJECTIVE: To observe the effect of methylene blue (MB) on the changes in plasma nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and visceral pathologic changes in rabbits with traumatic shock. METHODS: Eighteen rabbits were randomly assigned into 3 groups (n=6): sham operation group, traumatic shock with normal saline (NS) resuscitation group (NS group), and traumatic shock with MB resuscitation group (MB group). In NS group and MB group, hemodynamics was monitored, and plasma contents of NO, TNF-alpha and IL-6 were determined before shock, after shock, after resuscitation, and 0.5, 2 and 4 hours after resuscitation. In sham operation control group, hemodynamics monitoring and plasma contents of NO, TNF-alpha and IL-6 were also determined. Tissue samples of the liver and intestine were obtained after experiments for microscopic examination. RESULTS: Compared with NS group, hemodynamics was stable in MB group. The levels of plasma NO in rabbits after traumatic shock were much higher than those of before shock. In NS group, the levels of plasma NO were progressively increased after resuscitation, reaching peak level at 0.5 hour after resuscitation, then decreased thereafter but still remaining higher than those of before shock. But in MB group, the levels of plasma NO after resuscitation were obviously decreased. In sham operation group, the levels of plasma NO showed no significant changes during the whole course. The levels of plasma TNF-alpha and IL-6 in rabbits after traumatic shock were much higher than those of before shock. But after intravenous administration of MB, the levels of plasma TNF-alpha and IL-6 after resuscitation showed no significant difference compared with the baseline levels. In sham operation group, the levels of plasma TNF-alpha and IL-6 showed no significant changes during the entire course. In NS group, the organs showed prominent pathologic changes. But in MB group, less pathologic changes in the organs were milder, and in sham operation group, there was no obvious pathologic changes in the organs. CONCLUSION: NO, TNF-alpha and IL-6 play important roles in the pathologic process of traumatic shock and the administration of MB after resuscitation can decrease the levels of plasma NO, TNF-alpha and IL-6, improve hemodynamics in traumatic shock, and protect the important organs.