Population studies on Oncomelania quadrasi, the snail intermediate host of Schistosoma japonicum, in the Philippines. 3. Data transformation for significance test of snail density

For the comparative study of densities of Oncomelania quadrasi, the snail intermediate host of Schistosoma japonicum in the Philippines, the survey data should be transformed to stabilize the variance in determining the significant difference of densities among populations and to evaluate control measures by the difference, since the snail is distributed unevenly in the field. Comparison was made for the efficiency of stabilizing variance among 7 transformation formulas so far reported, and 2 new additional formulas in the present study. As a result, a simple transformation by y=log (x+0.01) was found to be most reliable. This nonparametric transformation can be applied to any snail population irrespective of the type of distribution and the degree of clumping. By this formula, there is no need to discard snail-free samples which are important to evaluate control measures. Using this transformation, snail survey data were analyzed in the areas where control measures were undertaken during the past several years. And significant reduction of snail densities was proven using the t-test.     

Photochemical reactions of high polymers. XIII. Photografting of methyl methacrylate onto the polymers bearing thiosulfate groups

Polymers bearing pendent thiosulfate groups, that is, sodium poly(vinyl benzyl thiosulfate) (PVBB) and the sodium salt of poly(vinyl hydrothiosulfatoacetate)(PV AcB), were prepared. The photograft polymerization of methyl methacrylate onto these polymers was carried out. The relationships between irradiation time and conversion, degree of grafting, and grafting efficiency were investigated in the photograft polymerization. It was ascertained that the pendent thiosulfate groups acted as effective initiators for the graft polymerization. From the number of endgroups in the homopolymer formed along with the graft polymer, the mechanism of the graft polymerization was discussed and it was verified that the graft polymerization was initiated by the thiyl radical formed by scission of the sulfur–sulfur bond of the pendent thiosulfate group. An unusually high degree of grafting and extremely rapid polymerization rate observed in the graft polymerization suggested the dual functions of thiosulfate-bearing polymer as initiator and emulsifier. It was found that addition of FeCl₂ to this polymerization system increased the rate of polymerization and the degree of grafting but decreased the grafting efficiency. The effect of FeCl₂ was interpreted by assumption of a photo-redox reaction between thiosulfate group and Fe²⁺.     

Arsenic metabolism. (17) Studies of placental transfer of arsenic and the effects of antidotes and diet

Albino rats of Wistar strain (Tamura 1950) breeded in a closed colony were administered arsenic trioxide orally during pregnancy (from the 0 day to the 20th day). Organs of fetuses and mother rats were exenterated on the 21st day of gestation and the contents of arsenic measured using an arsenic analyzer unit with atomic absorption spectrophotometry. Whole organs of the fetus were separated into 3 groupings i.e. liver, brain and remaining organs. The contents of arsenic in the organs in each of these groupings and in the placenta were measured. Even in the non-administered group, arsenic was detected in the every organ. In the arsenic administered group, the content of arsenic in the placenta was the highest among the four preparations tested; and the content in the liver and remaining organs was considerably high, but was low in the brain. The level of accumulation of arsenic differed between each organ. In the placenta, the accumulation reached a plateau, and in the brain this accumulation was below one-tenth that in the liver. In the non-administered group, arsenic was detected in the liver, kidney, spleen and brain of mother rats. In the group on arsenite, the content in the kidney and spleen was large, followed by a large amount in the liver and in the brain respectively. The level of accumulation of arsenic in mother rats differed between each organ. Arsenite was administered with antidotes such as dimercaprol, thioctic acid and L-ascorbic acid during pregnancy (from the 0 day to the 5th day). In this group the content of arsenic in the remaining organs was statistically less than that of the control group. The content in the brain was slightly reduced by a co-administration of the antidotes, however, there was no statistical difference in the placenta and liver between the antidote-treated and control groups. The content of arsenic in the kidney of mother rats treated with antidotes was statistically less than that of the controls. Whether or not the content of arsenic in organs of fetuses and mother rats was affected by a milk diet was also studied. The content of arsenic in the organs of fetuses showed no statistical difference between the animals on an Oriental stock diet group and those on the milk diet. On the other hand, the content of arsenic in the kidney of mother rats on the milk diet was statistically less than seen in those in the Oriental stock diet group.     

One-point method for determination of number-average molecular weight

The following well-known equation permits the ready determination of M _n from a single osmotic pressure measurement at a known concentration, if the second virial coefficient is previously given: On this basis, the one-point method was investigated to determine the number-average molecular weight. It was found that this method was applicable to commercial polymers. However, in this application, the dependence of Γ₂ on molecular weight distribution has to be kept in mind.     

Quantitative determination of isomeric glycerides,free fatty acids and triglycerides by thin layer chromatography-flame ionization detector system

Partial glyceride mixtures, which include 1-monoglyceride, 2-monoglyceride, free fatty acid, 1,2-diglyceride, 1,3-diglyceride and triglyceride, could be separated from each other on a 3% boric-acid-impregnated Chromarod S-II (silica gel sintered quartz rod) with either chloroform/acetone (96∶4, v/v) or chloroform/acetone/acetic acid (100∶1∶1, v/v) as the developing solvent mixtures. The components separated on the boric-acid-impregnated rod were automatically quantitated in a hydrogen flame ionization detector (Iatroscan). The relative responses of 1,2-diglyceride, 1,3-diglyceride, free fatty acid and triglyceride were slightly lower than theoretical responses based on weight percentage, whereas 1-monoglyceride and 2-monoglyceride showed slightly higher responses. These responses were converged within a maximal error of 5–10% (SD). Boric-acid-impregnated rods could be used repeatedly, ca. 5 times without any reconditioning procedure. Part of this investigation was reported at the 2nd JOCS-AOCS joint meeting, San Francisco, May 1979.