An efficient diastereoselective synthesis of 6-hydroxy-4a-[3,4-crowned(15-crown-5)phenyl]-trans-decahydroisoquinoline

A high diastereoselective synthesis of 6-hydroxy-4a-aryl-$\text{trans}$-decahydroisoquinoline derivatives was achieved by an application of N-acyliminium ion-induced polyene cyclization procedure.     

Preparation and luminescence properties of Y2(WO4)3: Eu3+

A red-emitting Y₂(WO₄)₃: Eu³⁺ phosphor (orthorhombic high temperature phase, anhydride) is prepared by two different methods: the firing of mixtures of constituent oxides and that of precipitates from aqueous solutions. After optimizing preparation conditions, the cathodoluminescence brightness reaches 56% that of Y₂O₂S: Eu³⁺, a commercial red phosphor for color TV. Formation of a high temperature phase below the reported transition temperature is noted in the fired precipitates. This phase occurrence is shown to depend on the treatment of the precipitates to be fired. Reflection difference measurement of Eu-doped and undoped samples assigns an excitation band of about 245 nm to the Eu-O charge transfer band. Different by-products in the two preparation methods are identified by measuring emission spectra under selective excitation. Reversible hydration-dehydration of the phosphor is demonstrated by successively measuring photoluminescence first in vacuum and then in air at various temperatures. No deterioration of luminescence efficiency is observed after repeating this reversible structural change.     

Isotope exchange between alkaline earth metal hydroxide and HTO water in the equilibrium state

In order to reveal to what extent tritium (³H or T) can be incorporated into hydroxides, the isotope exchange reaction (OT-for-OH exchange reaction) between each alkaline earth metal hydroxide (M(OH)₂), where M means alkaline earth metal (M=Ca, Sr or Ba) and HTO water was observed homogeneously at 30 °C under equilibrium after mixing. Consequently, the followings were obtained: (1) a quantitative relation between the electronegativity of each M ion and the ability (of the M ion) incorporating OT^– into the M hydroxide can be found and the ability is small when the temperature is high, (2) the exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the M ion in the M hydroxide in great, (3) as for the dissociation of HTO water, it seems that fomula (HTOT⁺+OH^–) is more predominant than the fomula (HTOH⁺+OT^–) when the temperature is high and (4) the method used in this work is useful to estimate the reactivity of a certain alkaline material.     

Preconcentration of copper with the ion-pair of 1,10- phenanthroline and tetraphenylborate on naphthalene

A solid ion-pair material produced from 1,10-phenanthroline and tetraphenylborate on naphthalene provides a simple, rapid and fairly selective means of preconcentrating copper from up to 1000 ml of aqueous samples (about 200-fold concentration is possible). Copper is quantitatively adsorbed in the pH range 1.6–10.4 at a flow rate of 3 ml min^?1. The solid mass (0.2 g) is dissolved from the column with 5 ml of dimethylformamide (DMF) and copper is measured by atomic absorption spectrometry at 324.7 nm. Linear calibration is obtained for 2–28 μg of copper in 5 ml of DMF solution. Replicate determination of 14 μg of copper gave a mean absorbance of 0.220 (n = 7) with a relative standard deviation of 1.5%. The sensitivity for 1% absorption was 0.093 μg ml^?1. After optimization, the method was applied to determine trace copper in standard reference materials, natural waters, beverages and hair.     

Spectrophotometric determination of palladium after coprecipitation of its 9,10-Phenanthrenequinone monoximate on microcrystalline naphthalene

Summary A spectrophotometric method has been developed for the microdetermination of Pd(II) as its 9,10-Phenanthrenequinone monoximate, by coprecipitation on solid naphthalene and dissolution in chloroform. The method can be applied to the determination of palladium in certain synthetic mixtures.

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Spektrophotometrische Bestimmung von Palladium nach Mitfällung seines 9,10-Phenanthrenchinonmonoximates auf mikrokristallines Naphthalin

Zusammenfassung Ein spektrophotometrisches Verfahren zur Mikrobestimmung von Pd(II) als 9,10-Phenanthrenchinonmonoximat durch Mitfällung auf festes Naphthalin und Lösung in Chloroform wurde ausgearbeitet. Dieses Verfahren eignet sich zur Bestimmung von Palladium in gewissen synthetischen Gemischen.

     

Synthesis and characterization of polyester dendrimers from acetoacetate and acrylate

New aliphatic polyester-type dendrimers were synthesized using a new AB2-type building block 3, prepared from benzyl acetoacetate and 2 equiv of tert-butyl acrylate by acetoacetic acid ester synthesis. The reiterative [deprotection by HCO2H, then EDCI/DMAP coupling] sequence using divergent growth method gave [G1]-4tBu-[G5]-64tBu dendrimers. 13C NMR relaxation time (T1) measurements on the carboxy carbons show that the extended chain conformations are predominant in CDCl3. [structure: see text]     

Quantitative analysis of the marker compounds in Salvia miltiorrihiza root and its phytomedicinal preparations

A HPLC method is described in order to separate and identify 4 phenolic compounds including lithospermic acid B, 3,4-dihydroxyphenyllactic acid (danshensu), rosmarinic acid, and protocatechuic aldehyde as well as 3 lipophilic ones (tanshinone I, tanshinone II(A) and cryptotanshinone) from the roots of Salvia miltiorrihiza or the herbal product containing S. miltiorrihiza available in Chinese or Japanese market. The influence of extractive conditions, such as method, solvents and time, on the 4 phenolic marker components in S. miltiorrihiza is well discussed. In order to investigate the stability of lithospermic acid B, the preparation samples of an injection and a granule were analyzed after being stored at 4 degrees C, 20 degrees C and 40 degrees C for up to six months.     

Detection and classification of organophosphate nerve agent simulants using support vector machines with multiarray sensors

The need for rapid and accurate detection systems is expanding and the utilization of cross-reactive sensor arrays to detect chemical warfare agents in conjunction with novel computational techniques may prove to be a potential solution to this challenge. We have investigated the detection, prediction, and classification of various organophosphate (OP) nerve agent simulants using sensor arrays with a novel learning scheme known as support vector machines (SVMs). The OPs tested include parathion, malathion, dichlorvos, trichlorfon, paraoxon, and diazinon. A new data reduction software program was written in MATLAB V. 6.1 to extract steady-state and kinetic data from the sensor arrays. The program also creates training sets by mixing and randomly sorting any combination of data categories into both positive and negative cases. The resulting signals were fed into SVM software for "pairwise" and "one" vs all classification. Experimental results for this new paradigm show a significant increase in classification accuracy when compared to artificial neural networks (ANNs). Three kernels, the S2000, the polynomial, and the Gaussian radial basis function (RBF), were tested and compared to the ANN. The following measures of performance were considered in the pairwise classification: receiver operating curve (ROC) Az indices, specificities, and positive predictive values (PPVs). The ROC Az) values, specifities, and PPVs increases ranged from 5% to 25%, 108% to 204%, and 13% to 54%, respectively, in all OP pairs studied when compared to the ANN baseline. Dichlorvos, trichlorfon, and paraoxon were perfectly predicted. Positive prediction for malathion was 95%.     

Three-component complexes of cyclodextrins. Exciplex formation in cyclodextrin cavity

The fluorescence quenching of naphthalene, 1-methylnaphthalene, and acenaphthene by trimethylamine (TMA) was studied in aqueous -cyclodextrin (-CD) solutions to know the structural requirements for guest molecules to form three-component complexes. The apparent rates for the fluorescence quenching of the naphthalene derivatives by TMA markedly increased in the presence of -CD. The fluorescence quenching of 1-methylnaphthalene and acenaphthene by TMA was accelerated by -CD more efficently than that of naphthalene. These results suggest the structures of the three-component complexes as the arene-capped -CD including TMA in its cavity.