An efficient procedure for preparation of 2-monoalkyl or 2-monoaryl-3-ethoxycyclobutanones

Optimized reaction conditions for the preparation of various 2-monosubstituted 3-ethoxycyclobutanones are described. 2-Monoalkyl 3-ethoxycyclobutanones were efficiently prepared by the reaction of the corresponding carboxylic acid chlorides and an excess amount of ethyl vinyl ether in the presence of diisopropylethylamine at 90 °C in a sealed tube. 2-Monoaryl 3-ethoxycyclobutanones were prepared by using 2,6-lutidine as a base in the above-mentioned procedure.     

The IR modulator utilizing light scattering effect with ferroelectric liquid crystal for gas analysis

Experimental infrared modulator elements have been fabricated utilizing the transient light scattering effect of ferroelectric liquid crystal with asymmetric waveform voltage drive. The new elements perform 80% modulation degrees at the 632.8nm. We have also achieved 30% modulation degrees in the 4 to 5µ m region where the strongest CO₂ absorption bands exist. A new type of analyzer which monitors ambient air quality has been developed. This analyzer uses non-dispersive infrared absorption method and composes of a double-beam, a single detector and a pair of liquid crystal light modulator as the IR chopper. The detection has achieved 10ppm noise equivalent concentration.     

Potentiation of ifosfamide toxicity by chlordiazepoxide, diazepam and oxazepam

The effects of chlordiazepoxide, diazepam and oxazepam on the lethal toxicity and metabolic activation of ifosfamide were investigated in mice. Ifosfamide was administered 24 h after the final injection of chlordiazepoxide, diazepam or oxazepam (100 mg/kg/d for 3 d, i.p.). The prior administration of chlordiazepoxide, diazepam or oxazepam enhanced the toxicity of ifosfamide (778 mg/kg, i.p.) during observation for 6 d after the administration of ifosfamide. In chlordiazepoxide-, diazepam- or oxazepam-treated mice, a higher concentration of active metabolite in the plasma after the administration of ifosfamide (200 or 600 mg/kg, i.p.) was observed as compared with that in mice treated with ifosfamide alone. On the other hand, chlordizepoxide, diazepam or oxazepam markedly enhanced the activity of ifosfamide oxidase in the liver microsomes. These results suggest that the potentiation of ifosfamide toxicity is due to stimulation of the metabolic activation of ifosfamide by chlordizepoxide, diazepam and oxazepam.     

Phase structure change and ER effect in liquid crystalline polymer/dimethylsiloxane blends

The mechanism of the electrorheological (ER) effect in two types of liquid crystalline polymer (LCP)/dimethylsiloxane (DMS) blends was investigated by rheological measurements and by structure observation under electric field and shear flow. The results show that the phase structures of these immiscible blends can be categorized into slipping (low viscosity) and non-slipping (high viscosity) states. In the non-slipping state, higher viscosity LCP domains connect the electrodes. In the slipping state, on the other hand, LCP domains do not connect the electrodes and the shear is mainly confined in the lower viscosity DMS domains. The ER effect (electrically induced viscosity increase) originates from the electrically induced slipping to non-slipping transition. In one of the blends, the ER effect occurs only at high shear rate, since this blend is in non-slipping state even under no field if the shear rate is low. Received: 29 April 1997 Accepted: 3 November 1997     

Rapid one-step synthesis, characterization and functionalization of silica coated gold nanoparticles

This paper describes a rapid, simple and one-step method for preparing silica coated gold (Au@SiO₂) nanoparticles with fine tunable silica shell thickness and surface functionalization of the prepared particles with different groups. Monodispersed Au nanoparticles with a mean particle size of 16 nm were prepared by citrate reduction method. Silica coating was carried out by mixing the as prepared Au solution, tetraethoxysilane (TEOS) and ammonia followed by microwave (MW) irradiation. Although there are several ways of coating Au nanoparticles with silica in the literature, each of these needs pre-coating step as well as long reaction duration. The present method is especially useful for giving the opportunity to cover the colloidal Au particles with uniform silica shell within very short time and forgoes the use of a silane coupling agent or pre-coating step before silica coating. Au@SiO₂ nanoparticles with wide range of silica shell thickness (5-105 nm) were prepared within 5 min of MW irradiation by changing the concentration of TEOS only. The size uniformity and monodispersity were found to be better compared to the particles prepared by conventional methods, which were confirmed by dynamic light scattering and transmission electron microscopic techniques. The prepared Au@SiO₂ nanoparticles were further functionalized with amino, carboxylate, alkyl groups to facilitate the rapid translation of the nanoparticles to a wide range of end applications. The functional groups were identified by XPS, and zeta potential measurements.     

Unusually large magnetic anisotropy in a CuO-based semiconductor Cu5V2O10

A CuO-based material Cu(5)V(2)O(10) was successfully grown in a closed crucible using Sr(OH)(2)·8H(2)O as flux. The structure of Cu(5)V(2)O(10) can be viewed as being composed of two types of zigzag Cu-O chains running along the b- and c-axes, which shows a two-dimensional crosslike framework with 12-column square tunnels along the a-axis. Magnetic measurements show that Cu(5)V(2)O(10) exhibits unexpected large magnetic anisotropy, which is the first time magnetic anisotropy energy of ～10(7) erg/cm(3) in the CuO-based materials has been observed. The origins of large anisotropy are suggested to arise from strong anisotropic exchanges due to the particular bonding geometry and the Jahn-Teller distortion of Cu(2+) ions. Further, the band structure investigated by the GGA+U method suggests that Cu(5)V(2)O(10) is a semiconductor.     

Integrated electrochemical-chemical oxidation mediated by alkoxysulfonium ions

Generation of carbocations by the "cation pool" method followed by reaction with dimethyl sulfoxide (DMSO) gave the corresponding alkoxysulfonium ions. Alkoxysulfonium ions could also be generated by in situ DMSO trapping of electrochemically generated carbocations. The resulting alkoxysulfonium ions were transformed into carbonyl compounds by treatment with triethylamine. The present integrated electrochemical-chemical oxidation can be applied to the oxidation of diarylmethanes to diaryl ketones, toluenes to benzaldehydes, and aryl-substituted alkenes to 1,2-diketones. Moreover, the oxidation of unsaturated compounds bearing a nucleophilic group in an appropriate position gives cyclized carbonyl compounds.     

Aromatic character of polycyclic π systems formed by fusion of two or more rings of the same size

The sequential line plot of topological resonance energy (TRE) against the number of π electrons (N(π)) for any polycyclic aromatic hydrocarbon (PAH) is very similar with the same number of extrema to that for benzene. Thus, global aromaticity of a PAH molecular ion strongly reflects that of a benzene molecular ion. Likewise, the N(π) dependence of TRE for any polycyclic π system formed by fusion of two or more rings of the same size reflects that for a monocyclic species of the same ring size. In general, TREs for such polycyclic π systems and their molecular ions can be interpreted consistently by reference to those for neutral and charged monocyclic species of the same ring size.     

Location of [60]fullerene incorporation in lipid membranes

We confirmed that most C(60) fullerene units are located in the hydrophobic core of the lipid bilayer membrane in water-soluble lipid membrane incorporated C(60) (LMIC(60)) complexes using differential scanning calorimetry (DSC) and (13)C NMR spectra in the presence of radical labels.     

Photoresponsive liposomal nanohybrid cerasomes

An innovative photoresponsive cerasome is fabricated by sol-gel process in combination of self-assembly technique from a molecularly designed organoalkoxysilylated lipid containing an azobenzene unit, which is able to operate as a "valve" with an "on-off" function under specific stimuli to control the release of loaded guest molecules from the liposomal membrane.