background: approximately 205 million pregnancies occur each year in the worldwide. on the other hand, spontaneous abortion has been reported in 15-20% of all diagnosed pregnancies. the most common cause of spontaneous abortion is chromosomal abnormalities of the embryo. robertsonian translocation carriers specially 21-14 are the most common balanced rearrangement among the carrier couples with...

a theoretical study of the kinetic and mechanism of 3-aug-cope rearrangement in gas phase was performed usingdet methods at b3lyp levels of theory with 6-3114ig(d,p) bass set at 298.i5k. equilibrium moleculargeometries and harmonic vibrational frequencies of the reactant, transition state did product were calculated. then,rate constant and activation thermodynamics parameters were calculated an...

microstructural investigation of low molecular weight 1,4-polybutadiene (1,4-pbd) was studied by 1h and 13c nuclear magnetic resonance spectroscopy (nmr). the isomer contents of 1,4-cis, 1,4-trans and 1,2- vinyl in polybutadiene microstructure were determined. the number average molecular weight for low molecular weight polybutadiene was measured by nmr techniques and comparison was made with g...

a facility layout problem is concerned with determining the best position of departments, cells, or machines on the plant. an efficient layout contributes to the overall efficiency of operations. it’s been proved that, when system characteristics change, it can cause a significant increase in material handling cost. consequently, the efficiency of the current layout decreases or is lost and it ...

nano silica-h2so4 is an efficient and mild catalysis system for the regeneration of aldehyde from aldoximes. ketoximes are converted to amides by beckmann rearrangement in the presence of nano silica-h2so4. the reactions are carried out in solvent-free conditions under microwave irradiation (600 w) within 50-120 sec in good yields.

As the basis and preliminary work of future experimental study on PAHs formation under high temperature, theoretical computations on the intramolecular rearrangement reactions of sylvestrene (1-methyl-3-vinylcyclohexene) and 1,4-dimethyl-4-vinylcyclohexene are conducted and reveal that they may be transformed to themselves. The conversion between Dipentene and 2,4-dimethyl-4-vinylcyclohexen...

Thermal rearrangement of propargyl naphthyl ethers produced naphthopyrans. In the presence of sodium methoxide, propargyl naphthyl ethers were converted easily to naphthofurans and naphthodifurans in good yields