1-Methylimidazole-catalyzed reaction between tosylmethyl isocyanide and dialkyl acetylenedicarboxylates:An efficient synthesis of functionalized pyrroles

An efficient 1-methylimidazole-catalyzed synthesis of dialkyl 2-[(4-methylphenyl)sulfonyl]-1H-pyrrole-3,4-dicarboxylates is described.The reactive 1:1 zwitterionic intermediate formed by the addition of 1-methylimidazole to dialkyl acetylenedicarboxylates is trapped by tosylmethyl isocyanide(TOSMIC) to afford the title compounds in excellent yields.     

Miniaturized Analysis of Methylhexanamine in Urine by Gas Chromatography Applying In Situ Derivatization

Chromatographia - The use of stimulants by professional and amateur athletes, as well as in the general population, to enhance their athletic performance represents a human health hazard....     

A series of 1,8-dioxooctahydroxanthenes are prepared using trichloroisocyanuric acid

A series of aromatic aldehydes are turned in to 3,3,6,6-tetramethyl-9-aryl-1,8-dioxooctahydroxanthene derivatives using trichloroisocyanuric acid(TCCA) as the catalyst.     

Microwave-assisted aldol condensation of benzil with ketones

Under microwave irradiation,the corresponding hydroxycyciopentenones were prepared in high yields by the cross-aldol reactions of benzil with various ketones.When the reactions were performed in vailOUS solvents under classical heating for a long time,they produced the products in relatively low yields.     

Chaos suppression of uncertain gyros in a given finite time

The gyro is one of the most interesting and everlasting nonlinear dynamical systems,which displays very rich and complex dynamics,such as sub-harmonic and chaotic behaviors.We study the chaos suppression of the chaotic gyros in a given finite time.Considering the effects of model uncertainties,external disturbances,and fully unknown parameters,we design a robust adaptive finite-time controller to suppress the chaotic vibration of the uncertain gyro as quickly as possible.Using the finite-time control technique,we give the exact value of the chaos suppression time.A mathematical theorem is presented to prove the finite-time stability of the proposed scheme.The numerical simulation shows the efficiency and usefulness of the proposed finite-time chaos suppression strategy.     

High-LET particle dosimetry in the ASTP-Biostack III: ZEA MAYS experiment

Abstract

High-LET particle hits in embryos of Zea mays (corn) seeds, flown as part of the ASTP-Biostack III, were determined via plastic nuclear track detectors. Based on etched particle-track measurements, 41 embryos were hit in seed layer 1 which contained 80 seeds, and 49 hits occurred in layer 2 which contained 79 seeds. The mean LET value and range of atomic numbers of recorded hits is, respectively, 210 ± 57 keV/μm and 9 ? Z ? 26. Detailed analysis of one particular seed showing marked growth anomalies revealed two hits in the central region of the embryo. These two hits had LET values in the region of 100–150 keV/μm, and Z ? 20.     

A convenient one-pot synthesis of new chromeno[3,4-c]chromene and chromeno[3,4-c]pyridine derivatives in the presence of high surface area of magnesium oxide

In this investigation a new strategy involves the one-pot,three-component reaction of malononitrile,salycilaldehyde and phenol derivatives in the presence of high surface area of MgO is extended to the formation of chromeno[3,4-c]chromene derivatives in good to excellent yields in a short reaction time.Also,the three component reactions of an aldehyde such as salycilaldehyde and ketones with malononitril for the formation of chromeno[3,4-c]pyridines are investigated.     

Synthesis,spectral studies,thermal behavior,and antibacterial activity of Ni(Ⅱ),Cu(Ⅱ),and Zn(Ⅱ) complexes with an ONO tridentate Schiff base

Three new transition metal complexes have been synthesized with a Schiff base,3-(2-hydroxy-5-chlorophenylimino)-l,3- diphenylpropen-1-one.In all complexes Schiff base is completely deprotonated and coordinated to metal as tridentate ligand via phenolic and enolic oxygens and imine nitrogen.Thermal decomposition of the complexes has been studied by thermogravimetry. The in vitro antibacterial activity of Schiff bases and their complexes has been evaluated and compared with the standard drugs.     

Adsorption of nitrous oxide on the(6,0) magnesium oxide nanotube

Nitrous oxide adsorption on the pristine（6,0） magnesium oxide nanotube was studied by using density functional theory calculations.We present the nature of the N₂O interaction in selected sites of the nanotube.Adsorption energies corresponding to adsorption of the N₂O on the nanotube were calculated to be in the range -11.67 to -22.21 kJ mol^-1.Our results indicate that the N₂O molecule has a weak physical adsorption on the pristine models due to weak Van der Waals interaction between the nanotubes and N₂O molecule.The important results can be useful in production of the N₂O sensors.