phospho sulfonic acid (psa) synthesized as an environmentally safe and efficient solid acid catalyst, and it used for the synthesis of several 2-disubstituted benzimidazoles, 2-substituted benzoxazoles, and 2-substituted quinoxalines in ethanol as a green solvent at ambient temperature is described. (i) a very simple, green and efficient procedure for the synthesis of benzimidazole and also benz...

the aim of this paper is detection of exist of significance climatic trend in west-half of iran. it’s used monthly data of 16 climatic variables on 12 selected synoptic stations in period of 50 years statistic(1951-2000). the variables divided to two temperature and humid groups. the analysis methodology of the study is based on multivariable statistical analysis and box- jenkins forecasting mo...

In this paper, we propose a parametric uniform approximation method to solve NP-hard absolute value equations. For this, we uniformly approximate absolute value in such a way that the nonsmooth absolute value equation can be formulated as a smooth nonlinear equation. By solving the parametric smooth nonlinear equation using Newton method, for a decreasing sequence of parameters, we can get the ...

titanium dioxide nanocrystals were synthesized by sol-gel method at room temperature. titanium isoprophoxide and absolute ethanol were used as precursors to prepare the sol. the ph of the solution was adjusted by adding nitric acid and sodium hydroxide solution. the prepared tio2 nanocrystals were annealed at 325°c, 425°c and 525°c respectively. the effect of ph on the surface morphology and st...

A two-stage 920–960 MHz power amplifier (PA) in GaAs heterojunction bipolar transistor (HBT) process is demonstrated for small-cell communications the lunar environment. To cope with temperature fluctuations during days, a novel complementary to absolute (CTAT) biasing scheme proposed PA achieve an ultra-wide-range compensation. Moreover, meet linearity requirements of applications while produc...

Photoacoustic thermography is a promising tool for temperature measurement in deep tissue. Here we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to c...