Preparation of functional polymer-microspheres by suspension copolymerization of ethylene glycol dimethacrylate with hydrophilic monomers

A study was made of suspension copolymerization of ethylene glycol dimethacrylate (EDMA) with some hydrophilic monomers (M₂) to prepare gel particles having a large number and various kind of functional groups on their surface. Delayed charge of M₂ to partially prepolymerized EDMA suspension resulted in the formation of favorable particles. The polymerization leveled off despite an appreciable amount of remaining M₂ in the aqueous phase, and the amount of copolymerized M₂ and the fraction of on-surface M₂ units depended significantly on the kind of M₂ as well as the mode of M₂ charge. These dependences were explained in terms of the partition coefficient of M₂ between EDMA and water and the monomer reactivity ratio.     

Studies on synthetic polymer plates with high surface energy. III. Diethylene glycol bis(allyl carbonate)–unsaturated sulfonic acid system

Synthetic polymer plates (GPs) with high surface energy were prepared by the two-step copolymerization process previously reported, using diethylene glycol bis(allyl carbonate) (CR-39) as M₁ monomer and unsaturated sulfonates [sodium vinyl sulfonate (VS^?Na⁺), potassium styrene sulfonate (StS^?K⁺), and sodium 2-sulfoethyl methacrylate (SEM^?Na⁺)] as M₂ monomer. The contact angle (θ_H) of water for the acid-treated (immersed in an aqueous 0.1 N HCl solution for 2 h) GPs decreased in the order StS^?K⁺, VS^?Na⁺, and SEM^?Na⁺. In the case of M₂ = SEM^?Na⁺, the θ_H value was about 20°. By adding NaCl in the immersion solution and changing the pH of the immersion solution, the θ_H values for the CR-39–SEM^?Na⁺ GPs were lowered to 18.9 and 13.1°, respectively. The θ_H values for the above GPs were smaller than those for the CR-39–acrylic acid or the CR-39–methacrylic acid GPs in the previous report, whereas the contact angle (θ_Na) of water for the former after alkali treatment (immersed in an aqueous 0.1 N NaOH solution for 2h) was larger than those for the latter. The former had durability of water wettability superior to the latter because of the difference in dissociation characteristic of the respective functional group.     

Extraction Behavior of Actinides and Metal Ions by the Promising Extractant,N,N,N′,N′-Tetraoctyl-3,6-dioxaoctanediamide (DOODA)

Abstract

The extraction of actinides, fission products, some non-nuclear elements, and nitric acid by N,N,N′,N′-tetraoctyl-3,6-dioxaoctanediamide (DOODA-C₈) in dodecane was extensively studied. Also studied was the extraction of HNO₃ and Nd(III) by the tetradodecyl analog of DOODA-C₈ in dodecane. Both extractants contain two ether oxygen atoms in the backbone chain carrying the two amide groups and can thus act as tetradentate ligands. The extractability of actinides decreases in the order Pu(IV) > U(VI), Am(III) > Np(V) in the extraction from nitric acid and Pu(IV) > Am(III) >> U(VI) in the extraction from perchloric acid. Ions of di-, tri-, tetra-, hexa-, and heptavalent metals strongly differ in the extractability by DOODA-C₈ but, except for lanthanides(III), there is no visible correlation of their distribution ratios with ionic radii. Due to the efficient extraction of actinides, weak extraction of fission products, and sufficient extraction capacity, DOODA-C₈ is a promising extractant for the recovery of minor actinides from high-level radioactive wastes.     

Recovery of U and Pu from Nitric Acid using N,N-di(2-ethylhexyl)butanamide (DEHBA) in Mixer-Settler Extractors

The recovery of U and Pu from nitric acid using N,N-di(2-ethylhexyl)butanamide (DEHBA) in mixer-settler extractors was calculated by a simulation code, and a continuous counter-current experiment using mixer-settler extractors was performed. The flow rate, stage number, and nitric acid concentration were chosen as the parameters for the calculation, and the simulation code provided appropriate experimental conditions for separating U from Pu. The continuous counter-current experiment was carried out with three mixer-settler extractors consisted of the following 5 steps: U–Pu extraction (6 stages), Scrub (10 stages), U recovery (6 stages), Pu back-extraction (10 stages), and U back-extraction (16 stages). The results of the continuous counter-current experiment showed that the percentages of U and Pu extracted using 1.5 mol/dm³ (M) DEHBA from 4 M nitric acid were > 99.9% and 97.84%, respectively. Extracted Pu was back-extracted to the aqueous phase via contact with 0.15 M nitric acid, while most of the U content remained in the organic phase. Uranium in the organic phase was then back-extracted via contact with 0.01 M nitric acid, and the percent of U in the U fraction stream was 96.06%. The percentages of U and Pu in the Pu fraction stream were 3.94 % and 97.48%, respectively.     

RADIOLYSIS OF DIISODECYL PHOSPHORIC ACID AND ITS EFFECT ON THE EXTRACTION OF NEPTUNIUM

Radiolysis of diisodecyl phosphoric acid (DIDPA) in n-dodecane containing tributyl phosphate (TBP) was examined by analyzing concentrations of acidic extractants and H₃PO₄, and its effect on the extraction of neptuniua was studied froi the aspect of the extraction rate. For the solvent containing 0.5 fi DIDPA and 0.1 1 TBP Irradiated in the absence of HNO₃, G-values for degradation of DIDPA and for production of dibutyl phosphoric acid (DBP)were found to be 0.47 and 0.14, respectively. For the solvent irradiated in stationary contact with 0.5 M HNO3, G-value for DIDPA degradation was found to be 0.78, which ras 1.7 tines larger than the value for the solvent irradiated in the absence of HNO₃.     

Prevalence of Arcobacter species in retail meats and antimicrobial susceptibility of the isolates in Japan

A survey was conducted to examine the prevalence of Arcobacter species among meat samples and to investigate the antimicrobial susceptibility of the isolates in Japan. In 1998 and 1999, samples of beef (n=90), pork (n=100) and chicken meat (n=100) were purchased from seven retail shops. Arcobacter species were isolated from 2.2%, 7.0% and 23.0% of beef, pork and chicken meat samples, respectively. The rate of isolations in chicken meats was shown to be significantly higher than those of beef and pork. Species-specific polymerase chain reaction (PCR) demonstrated that the most dominant Arcobacter species was Arcobacter butzleri among the isolates examined. Multiple contaminations with different Arcobacter species were observed in 5% of the chicken samples. Almost all the strains tested showed resistance to vancomycin (100%) and methicillin (97.5%). Strains resistant to cephalothin, sulfamethoxazole–trimethoprim, nalidixic acid and chloramphenicol were detected at the rate of 81.1%, 67.2%, 53.5% and 24.6%, respectively. All Arcobacter strains examined were susceptible to ampicillin, tetracycline, streptomycin and kanamycin.     

Possible immunodulating activities in an extract of edible brown alga,Hijikia fusiforme (Hijiki)

A significant immunomodulating activity was found in the hot-water-soluble extract of an edible brown seaweed, Hijikia fusiforme (Hijiki in Japanese) which showed an enhancing activity for the proliferative response of spleen cells in endotoxin-nonresponder C3H/HeJ mice. This activity was separated into polysaccharide and nonpolysaccharide fractions. The former fraction exhibited a much higher activity than that of the latter fraction. The enhancing effect of the polysaccharide fraction on the proliferative response of spleen cells was associated with the response of the B cell population, but not with that of the T cell population judged by experiments using nylon wool column-purified T cells and antisera against B cell- or T-cell-specific antigens. The active component of the polysaccharide fraction was further fractionated using DEAE cellulose column chromatography which also caused enhancing effects on polyclonal antibody (IgM and IgG) production and the release of interleukin-1α or tumour necrosis factor-α from peritoneal macrophages of C3H/HeJ mice. In addition, these immunomodulating activities of the polysaccharide fraction were associated with the polysaccharides themselves, but not with the artificial activities induced by contaminated endotoxins. The biochemical and physicochemical properties of the immunoenhancing polysaccharides were partially characterised and the significance of the present finding is discussed from the viewpoint of the immunopotentiating activity of edible seaweeds against carcinogenesis. © 1998 SCI.     

Laminar burning velocities and flame characteristics of CO–H2–CO2–O2 mixtures

Laminar burning velocities of CO–H₂–CO₂–O₂ flames were measured by using the outwardly spherical propagating flame method. The effect of large fraction of hydrogen and CO₂ on flame radiation, chemical reaction, and intrinsic flame instability were investigated. Results show that the laminar burning velocities of CO–H₂–CO₂–O₂ mixtures increase with the increase of hydrogen fraction and decrease with the increase of CO₂ fraction. The effect of hydrogen fraction on laminar burning velocity is weakened with the increase of CO₂ fraction. The Davis et al. syngas mechanism can be used to calculate the syngas oxyfuel combustion at low hydrogen and CO₂ fraction but needs to be revised and validated by additional experimental data for the high hydrogen and CO₂ fraction. The radiation of syngas oxyfuel flame is much stronger than that of syngas–air and hydrocarbons–air flame due to the existence of large amount of CO₂ in the flame. The CO₂ acts as an inhibitor in the reaction process of syngas oxyfuel combustion due to the competition of the reactions of H + O₂ = O + OH, CO + OH = CO₂ + H and H + O₂(+M) = HO₂(+M) on H radical. Flame cellular structure is promoted with the increase of hydrogen fraction and is suppressed with the increase of CO₂ fraction due to the combination effect of hydrodynamic and thermal-diffusive instability.