LACK OF GENOTOXIC EFFECTS OF PIPERINE, (THE ACTIVE PRINCIPLE OF BLACK PEPPER) IN ALBINO MICE

The potency of piperine, the active principle of black pepper, to induce micro-nuclei in bone-marrow erythrocytes and dominant-lethal mutations was investigated in male mice. Preliminary studies indicated that piperine administered (i.p.) to adult male mice at sublethal doses of 1,2 or 4 mg/kg b.w. (1/20, 1/10 or 1/15 LD₅₀) on 5 consecutive days did not induce any clinical signs of toxicity or any significant alterations in epididymal weights, testicular weights or tes-ticular histology. In the bone-marrow micronucleus assay, piperine induced no significant increase in micronuclei in polychromatic erythrocytes suggesting its nonclastogenic nature at the tested doses. Further, it also failed to induce dominant-lethal mutations during an 8–week sequential mating schedule of males at a dosage of 4 mg/kg b.w./ day for 5 days. The caudal sperm counts and the incidence of sperm-head abnormalities measured at 1,3,5 and 7 week were not altered in Piperine administered males at any of the doses.     

多级热处理工艺对铝合金AA7049性能的影响(英文)

T6态高强7xxx系列铝合金对应力腐蚀开裂敏感。采用回归和再时效热处理(RRA)可以提高其抗应力腐蚀开裂性能而不降低其强度性能。研究了多级热处理工艺对7049铝合金性能和组织的影响。通过电导率测量、DSC分析和TEM组织观察,考察合金在不同热处理态的组织变化。DSC分析表明,RRA处理会导致合金的显微组织发生显著变化,RRA处理态合金的组织与T6和T73态合金的组织明显不同。RRA处理可以使合金保持在T6态的强度且获得T73态的热力学稳定性能。     

Synthesis of polyaniline/ZrO<Subscript>2</Subscript> nanocomposites and their performance in AC conductivity and electrochemical supercapacitance

Polyaniline/zirconium oxide (PANI/ZrO₂) nanocomposites have been synthesized by incorporating ZrO₂ nanoparticles into the PANI matrix via liquid–liquid interfacial polymerization method. The composite formation and structural changes in PANI/ZrO₂ nanocomposites were investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). PXRD pattern of PANI/ZrO₂ nanocomposites exhibited sharp and well-defined peaks of monoclinic phase of ZrO₂ in PANI matrix. SEM images of the composites showed that ZrO₂ nanoparticles were dispersed in the PANI matrix. The FT-IR analysis revealed that there was strong interaction between PANI and ZrO₂. AC conductivity and dielectric properties of the nanocomposites were studied in the frequency range, 50–10⁶ Hz. AC conductivity of the nanocomposites obeyed the power law indicating the universal behaviour of disordered media. The nanocomposites showed high dielectric constant in the order of 10⁴, which could be related to dielectric relaxation phenomenon. Further, the materials were checked for their supercapacitance performance by using cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). Among the synthesized nanocomposites, PANI/ZrO₂-25 wt.% showed a higher specific capacitance of 341 F g^?1 at 2 m Vs^?1 and good cyclic stability with capacitance retention of about 88% even after 500 charge–discharge cycles.