Determination of levulinic acid in soy sauce by liquid chromatography with mass spectrometric detection

A novel method using liquid chromatography coupled with mass spectrometry (LC–MS) was developed for the determination of levulinic acid (LV) in soy sauces to identify the addition of acid hydrolyzed vegetable protein (acid-HVP). One hundred percentage naturally brewed soy sauce (NBS) and enzymatic hydrolyzed vegetable protein (enzymatic HVP) did not contain LV (<0.01 mg/mL). There was apparent detection of LV in acid-HVP and blended soy sauce with acid-HVP (2.98–21.66 mg/mL). Gas chromatography (GC) and high performance liquid chromatography (HPLC) at 430 nm methods were also investigated. The results by GC gave similar data to those by LC–MS. In enzymatic HVP, LV was detected by HPLC at 430 nm, but it was confirmed that the detected component was not in fact LV by mass spectrometric identification of the isolated peak compound. We found that LV is under the detection limit in enzymatic HVP. This study showed that LV is below the detection limit in NBS and enzymatic HVP and is apparently detected in acid-HVP and blended soy sauces with acid-HVP. These results indicate that LV is a practical index of blend with acid-HVP and also corresponds with the JAS (Japanese Agricultural Standard) or CNS (Chinese National Standard) criteria in which the presence of LV in soy sauces indicates adulteration with acid-HVP. The LC–MS method is analytically optimal for the precise determination of LV, because peak misidentification may be practically eliminated.     

Fabrication and Characterization of Colossal Electroresistance Chip Devices Composed of Polycrystalline Lanthanum-Doped Strontium Titanate and Palladium Electrodes

A colossal electroresistance (CER) multilayered chip device composed of polycrystalline 0.8-at% La-doped SrTiO₃ and Pd electrodes has been successfully fabricated. Polycrystalline SrTiO₃ devices exhibit large hysteresis in their current–voltage ( I – V ) characteristics after the forming process. Further, their resistance states can be switched by applying voltage pulses above ±50 V, and the resistance changes by approximately two orders of magnitude (from ∼600 Ω to ∼80 kΩ). These resistance-switching behaviors demonstrate that even ceramics can exhibit resistance changes as large as thin-film devices and provide the possibility of new switching devices with the memory effect composed of ceramics.     

Amidoxime resins based on poly(acrylonitrile-co-vinylidene chloride-co-divinylbenzene) and their behavior in uptake of uranium from sea water

Amidoxime resins were derived from poly(acrylonitrile-co-vinylidene chloride-co-divinyl-benzene) beads, which were prepared by suspension polymerization of the ternary monomeric mixtures in the presence of 4-methyl-2-pentanone (MIBK) or 1,2-dichloroethane (DCE) as the diluent (porogen), in order to clarify the effect of copolymerized vinylidene chloride on properties of the resulting amidoxime resins. Pore structure analyses of the copolymers as well as of their amidoximated derivatives clarified that MIBK yields larger pores than does DCE and then the latter gives larger specific surface areas than does the former. On the other hand, chemical properties of the amidoximated resins, such as anionexchange capacities and uranyl ion uptake, were not eseentially affected by the diluent species, indicating that both MIBK and DCE as the porogen lead to the amidoxime resins with almost the same ability in recovery of uranium from sea water. The uranium recovery decreased with increase in the vinylidene chloride content, but the decrease in the recovery was minor up to the 10 mol % of vinylidene chloride. It was also clarified that the uranium recovery by the amidoxime resins containing vinylidene chloride is greatly enhanced by the alkali treatment. © 1994 John Wiley & Sons, Inc.     

Regeneration of initial activity of a pitch-based ACF for NO–NH3 reaction at ambient temperature

The reactivity of adsorbed NO (including NO₂) and NH₃ in the presence of 4.0% oxygen in He was examined over a pitch-based ACF calcined at 800°C. Regeneration at 30°C by 4% O₂ in He without NH₃ was found to be optimum for the recovery of the initial activity with complete removal of NO within 3 h, with minimum leaks of adsorbed NO and NH₃. A higher temperature of 40°C for regeneration increased the liberation of adsorbed NO, and NH₃ over ACF was rather slow at a lower temperature of 25°C, slow regeneration being achieved. Oxygen appears necessary to regenerate the ACF through enhancing the reaction of adsorbed NO and NH₃ for the initial activity, which was ascribed to the catalytic activity for NO–NH₃ and adsorption of both NO and NH₃. NH₃ in the gas phase appears to inhibit the regeneration reaction of adsorbed species, by using the leaking amount during the regeneration.     

In vivo EPR dosimetry to quantify exposures to clinically significant doses of ionising radiation

As a result of terrorism, accident or war, populations potentially can be exposed to doses of ionising radiation that could cause direct clinical effects within days or weeks. There is a critical need to determine the magnitude of the exposure to individuals so that those with significant risk can have appropriate procedures initiated immediately, while those without a significant probability of acute effects can be reassured and removed from the need for further consideration in the medical/emergency system. It is extremely unlikely that adequate dosemeters will be worn by the potential victims, and it also will be unlikely that prompt and accurate dose reconstruction at the level of individuals will be possible. Therefore, there is a critical need for a method to measure the dose from radiation-induced effects that occur within the individual. In vivo EPR measurements of radiation-induced changes in the enamel of teeth is a method, perhaps the only such method, which can differentiate among doses sufficiently to classify individuals into categories for treatment with sufficient accuracy to facilitate decisions on medical treatment. In its current state, the in vivo EPR dosemeter can provide estimates of absorbed dose of +/- 0.5 Gy in the range from 1 to >10 Gy. The lower limit and the precision are expected to improve, with improvements in the resonator and the algorithm for acquiring and calculating the dose. In its current state of development, the method is already sufficient for decision-making action for individuals with regard to acute effects from exposure to ionising radiation for most applications related to terrorism, accidents or nuclear warfare.     

Arsenate removal from water by a weak-base anion exchange fibrous adsorbent

A weak-base anion exchange fiber named FVA with primary amino groups for selective and rapid removal of arsenate species was prepared by means of electron irradiation induced liquid phase graft polymerization of N-vinylformamide onto polyethylene coated polypropylene fibers and by the subsequent alkaline hydrolysis of amide group on the grafted polymer chains. Two types of FVA were prepared. One was a non-woven cloth type named FVA-c for the batch-mode study, which clarified that uptake of arsenate species decreases with an increase in pH, and chloride and sulfate do not strongly interfere with uptake of arsenate species different from conventional anion exchange resins based on crosslinked polystyrene matrices. The other was a filamentary type one named FVA-f used in the column-mode study, which clarified that arsenate species were successfully removed from neutral pH arsenate solutions containing 1.0-99 mg of As/L at feed flow rates of 100-1050 h(-1) in space velocity (SV). The most important findings are that the 1% breakthrough point in uptake from the arsenate solution containing 1.0mg of As/L at the high feed flow rate of 1050h(-1) in SV was as large as 4670 bed volumes, giving the 1% breakthrough capacity of 0.298 mmol/g of FVA-f. Adsorbed arsenate was able to be quantitatively eluted with 1M hydrochloric acid and FVA-f was simultaneously regenerated. Then, the repeated use of FVA-f was possible.     

Thermoresponsive Emission Switching via Lower Critical Solution Temperature Behavior of Organic–Inorganic Perovskite Nanoparticles

Lead halide perovskites have shown much promise for high‐performing solar cells due to their inherent electronic nature, and though the color of bright‐light emitters based on perovskite nanoparticles can be tuned by halide mixing and/or size control, dynamic switching using external stimuli remains a challenge. This article reports an unprecedented lower critical solution temperature (LCST) for toluene solutions containing methylammonium lead bromide (MAPbBr₃), oleic acid, alkylamines, and dimethylformamide. The delicate interplay of these molecules and ions allows for the reversible formation and decomposition of MAPbBr₃ nanoparticles upon heating and cooling, which is accompanied by green and blue photoemissions at each state. An intermediate 1D crystal with PbBr₂‐amine coordination is found to play pivotal role in this, and a mechanistic insight is provided based on a three‐state model. In addition to a high quantum yield (up to 85%), this system allows for control over the cloud point (30?80 °C) through compositional engineering and the luminescent color (blue to red) via halogen exchange, thus making it a versatile solution for developing functional molecular organic–inorganic LCST quantum dots.