Magnesium hydroxide (Mg(OH)2) nanorods were synthesized by a simple and facile hydrothermal method in the presence of cetyltetramethylammonium bromide (CTAB) as a surfactant. Nanorods of magnesium oxide MgO were also induced by thermal decomposition of Mg(OH)2 nanorods at 700℃. By using disk diffusion technique, the Mg(OH)2 nanorods were found to exhibit higher antibacterial efficiency against several tested bacterial strains. Keywords:

Mn 3 O 4 nanoparticles were prepared by a simple chemical route using cetyltetramethylammonium bromide (CTAB) as a template agent. Mn 3 O 4 nanocrystals present an octahedral shape, and their crystallite size varies between 20 and 80 nm. They were characterized by XRD, SEM, DTA/TG, and IR spectroscopy. XRD studies confirm the presence of a highly crystalline Mn 3 O 4 phase. The Rietveld refinement of the X-ray diffraction data confirms that Mn 3 O 4 nanoparticles crystallize in the tetragonal system with space group I41/amd. DTA/TG and XRD measurements demonstrate the phase transition toward a spinel structure between 25 and 700 • C. The electrical conductivity increases between 80 and 300 • C, suggesting a semiconducting behaviour of Mn 3 O 4 . Both dielectric dispersion (ε ) and dielectric loss (ε ) were investigated from 80 and 300 • C in the frequency range of 10 Hz-13 MHz. The dielectric properties showed typical dielectric dispersion based on the Maxwell-Wagner model.

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α−MoO3 ordered nanosheets have been synthesized under hydrothermal conditions using commercial MoO3 and hydroquinone as structuring agent. X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to analyse the obtained material. The conductivity mechanism of the Molybdenum ordered nanosheets has been investigated using combined complex impedance and modulus formalism.The temperature dependence of the conductivity, which was between 473 and 573 K, is very close to the Arrhenius' law, with an activation energy of 0.76 eV. However, the conductivity of the material increases with temperature. It shows a typical negative temperature coefficient resistance (NTCR) similar to that of a semiconductor. The dielectric properties of the MoO3 compound have been studied in the temperature range of 473-573 K as well as the frequency range of 10 Hz to 13 MHz. The ac-conductivity for high frequency σac(ω) obeys the universal power law.

Chiral smectic liquid crystals exhibit a series of phases, including ferroelectric, antiferroelectric, and ferrielectric commensurate structures as well as an incommensurate Sm-Calpha* phase. We carried out an extension of the phenomenological model recently presented by Hamaneh and Taylor based on the distorted-clock model. The salient feature of this model is that it links the appearance of phases to a spontaneous microscopic twist: i.e., an increment alpha of the azimuthal angle from layer to layer. The balance between this twist and an orientational order parameter J gives the effective phase. We introduce a second orientational order parameter I , which physical meaning comes from the macroscopic polarization; the effect of an applied electric is also studied. We derive phase diagrams and correlate them to our experimental results under field showing the sequence of phases versus temperature and electric field in some compounds.