Convergent and stereoselective synthesis of vitamin D3 via 3,5-cyclovitamins D3

A convergent and stereoselective synthesis of vitamin D₃ was achieved via 3,5-cyclovitamins D₃ (20) which were prepared from the chiral aldehyde (2) and the vinyl bromide (12) derived from Grundmann's ketone.     

A remark on an example of a 6-dimensional Einstein almost-Kähler manifold

In this paper, we introduce a 6-dimensional example of non-compact complete Einstein non-K?hler almost-K?hler manifold G with negative scalar curvature which was constructed by Apostolov-Drăghici- Moroianu ([5]) and discuss the geometric structures.      

A 128 × 128 Pixel Complementary Metal Oxide Semiconductor Image Sensor with an Improved Pixel Architecture for Detecting Modulated Light Signals

A complementary metal oxide semiconductor (CMOS) image sensor for the detection of modulated light under background illumination has been developed. When an object is illuminated by a modulated light source under background illumination the sensor enables the object alone to be captured. This paper describes improvements in pixel architecture for reducing fixed pattern noise (FPN) and improving the sensitivity of the image sensor. The improved 128 × 128 pixel CMOS image sensor with a column parallel analog-to-digital converter (ADC) circuit was fabricated using 0.35-mm CMOS technology. The resulting captured images are shown and the properties of improved pixel architecture are described. The image sensor has FPN of 1/28 that of the previous image sensor and an improved pixel architecture comprising a common in-pixel amp and a correlated double sampling (CDS) circuit. The use of a split photogate increases the sensitivity of the image sensor to 1.3 times that of the previous image sensor.     

Application of an atmospheric pressure helium microwave-induced plasma as an element-selective detector for gas chromatography

An atmospheric pressure helium microwave-induced plasma (MIP) was combined with a gas chromatograph (GC). and used as an element-selective detector for GC. The detection limits, dynamic ranges and selectivities were obtained for H, C, F, Cl, Br, I and S. Such data for nitrogen and oxygen could not be obtained because of the interference from air which was entrained into the system through the leakages of the tubing and the valve system. The detection limits and dynamic ranges for all the elements investigated were in a range between 1.8 and 39pgs^?1 and between 1.6 × 10³ and 1.1 × 10⁵, respectively. Furthermore, the relative sensitivities of C, H, Cl and Br for various compounds were examined. In the cases of carbon and hydrogen, the relative sensitivities were not the same for different compounds containing oxygen and nitrogen. This result may be explained by the incomplete decomposition of such compounds due to the low microwave power (75 W) applied in the present system.     

Studies on the syntheses of heterocyclic compounds—DXLVIII : Synthesis of a hasubanan ring system from the benzylisoquinoline reticuline

The synthesis of a cepharamine analogue (19) from reticuline (1) by phenolic oxidation is reported. Reticuline was converted into the methine base (13b), whose dihydro compound (14c) was oxidised to the seco-morphinandienone (17b). Michael-type cyclization of 17b, followed by an isomerization of the enone (18) gave the cepharamine-type compound (19).     

Radiation-induced cis–trans isomerization of polyisoprenes and temperature dependence of the equilibria

The cis-trans interconversion of polyisoprenes in solutions induced by γ-radiation in the presence of a sensitizer, which is any one of organic bromides or n-butyl mercaptan, was studied by using hevea and gutta percha as starting substances. The percentage cis remaining or converted after irradiation were determined by the infrared absorption. The equilibrium constants for the interconversion at 22, 60, and 100°C. were found to be 3.00, 5.25, and 7.33, respectively. The first-order rate constants for cis → trans and trans → cis isomerizations at 22°C. were calculated to be 9.05 and 2.91, respectively. The results were interpreted by the mechanism proposed by Golub, according to which the double bonds from π complexes with radiolytic fragments from sensitizers give a radical transition state capable of interconversion. However, our results showing that heating shifts the equilibrium toward trans isomer are not in accord with the mechanisms of the radiation-induced isomerization of polybutadiene of Golub and those for photoisomerization of aromatic azo compounds.