微乳化切削液的生物毒性试验研究

分析了现行的切削液生物毒性的测定方法及弊端。采用小金鱼对配制的一种微乳化切削液进行毒性试验。试验结果表明:配制的微乳化切削液在生物毒性方面是环境兼容的。本研究对切削液的生物毒性检测具有参考价值。     

利用发光菌测量汽油发动机润滑油生物毒性的试验研究

利用发光菌作为受试物种,参照美国材料与试验学会ASTMD6081和国标GB/T15441进行汽油机润滑油生物毒性的试验研究。介绍了试验所用器材、润滑油水溶性馏分（WSF）和可容纳水馏分（WAF）的制备过程及生物毒性试验方法,对我国目前使用的3种典型的汽油机水冷润滑油进行了发光菌毒性实际检测,试验研究表明,利用发光菌作为汽油机润滑油急性生物毒性检测具有一定的科学性和先进性。试验中发光菌与毒液的接触时间为15-20s,制备WAF过程中转速为1200r/min搅拌时间6h条件下,分别测得3种润滑油WSF的毒性半致死量LD50,参照我国“急性毒性（LD50）剂量分级”3种润滑油相当于大鼠口服半致死量的无毒级别,相当于人的致死量低毒级别。     

A Direct GPC Calibration for Low Molecular Weight Polybutadiene,Employing Dual Detectors

Abstract

The calibration of gel permeation chromatograph (GPC) for a given polymer type is usually done by running well-characterized polymer samples of the same type. The available polystyrene and polyglycol standards with molecular weights below 5000 do not give parallel calibration curves, and the points for polystyrene are not on an extension of the higher-molecular-weight portion of the curve. In order to check the calibration in this low molecular-weight region and to establish an independent curve for polybutadiene, a polybutadiene sample prepared by a-methylstyrene tetramer-Na₂ initiation was chromatographed. In doing this, dual detection was used, consisting of a differential refractometer, and an ultraviolet absorption spectrophotometer.

The UV signal from the spectrophotometer was assumed to represent the tetramer portion of the polymer, and its percentage was calculated at each volume increment, using externally determined response factors. This percentage and the tetramer molecular weight gives the molecular weight of the polymer eluting at each volume increment. After correction for the aromatic portion of the polymer, these data and the points obtained with the polybutadiene standards were found to give a reasonable calibration curve for the entire range. The present paper describes the application of this technique to the examination of low molecular-weight polybutadiene.     

Possibility of Japanese Cedar Pollen Causing False Positives in the Deep Mycosis Test

Because Japanese cedar pollen (JCP) contains beta-1,3-d-glucan (BG), there is concern that its lingering presence in the atmosphere, especially during its scattering period, may cause false positives in the factor-G-based Limulus amebocyte lysate (LAL) assay used to test for deep mycosis (i.e., G-test). Hence, we examined whether the LAL assay would react positively with substances contained in JCP by using the G-test to measure JCP particles and extracts. BG was purified from the JCP extract on a BG-specific affinity column, and the percentage extractability was measured using three different BG-specific quantitative methods. The G-test detected 0.4 pg BG in a single JCP particle and 10 fg from a single particle in the extract. The percentage extractability of JCP-derived BG was not significantly different among the three quantitative methods. As the JCP particles should technically have been removed during serum separation, they should be less likely to be a direct false-positive factor. However, given that the LAL-assay-positive substances in the JCP extract were not distinguishable by the three BG-specific quantitative methods, we conclude that they may cause the background to rise. Therefore, in Japan false positives arising from JCP contamination should be considered when testing patients for deep mycosis.     

An immunomagnetic-bead-based enzyme-linked immunosorbent assay for sensitive quantification of fumonisin B1

A sensitive enzyme-linked immunosorbent assay (ELISA) based on immunomagnetic beads (IMB-ELISA) was established using a magnetic-bead signal-enrichment system. The immunomagnetic beads were coated with polyclonal antibody directed against keyhole limpet hemocyanin (KLH), which were then coupled with a KLH–fumonisin B1 (FB1) conjugate. Anti-FB1 monoclonal antibody and sample extract were mixed and added to the immunomagnetic-bead solution. After the addition of horseradish peroxidase (HRP)-labeled goat anti-mouse antibody and the substrate solution, stop solution was added and the optical density of the reaction mixture was determined. To improve the performance of this method, the dilution of the immunomagnetic beads, the concentrations of the monoclonal antibody and HRP-labeled goat anti-mouse antibody, and the incubation time for the competition reaction were optimized. Based on the optimum conditions, the regression equation for this IMB-ELISA in quantifying FB1 was y = −0.3538x + 0.703 (R² = 0.9988). The detection limit and IC₅₀ were 0.24 ng/mL and 3.17 ng/mL, respectively. The working range was 0.54–26.3 ng/mL. The recovery rates were 80.4–114.7%, when the spiked concentrations ranged from 19.5 to 156.3 μg/kg. This IMB-ELISA is accurate and more sensitive and less time-consuming than the conventional ELISA.     

Quantification of 1,8‐cineole and of its metabolites in humans using stable isotope dilution assays

The metabolism of 1,8‐cineole after ingestion of sage tea was studied. After application of the tea, the metabolites 2‐hydroxy‐1,8‐cineole, 3‐hydroxy‐1,8‐cineole, 9‐hydroxy‐1,8‐cineole and, for the first time in humans, 7‐hydroxy‐1,8‐cineole were identified in plasma and urine of one volunteer. For quantitation of these metabolites and the parent compound, stable isotope dilution assays were developed after synthesis of [²H₃]‐1,8‐cineole, [9/10‐²H₃]‐2‐hydroxy‐1,8‐cineole and [¹³C,²H₂]‐9‐hydroxy‐1,8‐cineole as internal standards. Using these standards, we quantified 1,8‐cineole by solid phase microextraction GC‐MS and the hydroxyl‐1,8‐cineoles by LC‐MS/MS after deconjugation in blood and urine of the volunteer. After consumption of 1.02 mg 1,8‐cineole (19 μg/kg bw), the hydroxycineoles along with their parent compound were detectable in the blood plasma of the volunteer under study after liberation from their glucuronides with 2‐hydroxycineole being the predominant metabolite at a maximum plasma concentration of 86 nmol/L followed by the 9‐hydroxy isomer at a maximum plasma concentration of 33 nmol/L. The parent compound 1,8‐cineole showed a low maximum plasma concentration of 19 nmol/L. In urine, 2‐hydroxycineole also showed highest contents followed by its 9‐isomer. Summing up the urinary excretion over 10 h, 2‐hydroxycineole, the 9‐isomer, the 3‐isomer and the 7‐isomer accounted for 20.9, 17.2, 10.6 and 3.8% of the cineole dose, respectively.     

Quantitation of estragole by stable isotope dilution assays

Various calibration strategies for the quantitation of the phenylpropane estragole by gas chromatography-mass spectrometry were developed and compared. For application in stable isotope dilution assays, two deuterium labelled estragole isotopologues were synthesized. Of these, [3′,3′-²H₂]estragole was prepared by Wittig reaction of 4-methoxy-phenylacetaldehyde with [²H₃]methyl-triphenyl-phosphonium bromide, whereas [1″,1″,1″-²H₃]estragole was obtained by demethylation of estragole and deuteromethylation of the resulting 4-allylphenole.Besides estragole isotopologues, 1,2,4-trimethoxybenzene and 4-propylanisole were also tested as internal standards (I.S.) for the determination of estragole in fennel tea.[1″,1″,1″-²H₃]Estragole, 1,2,4-trimethoxybenzene, and 4-propylanisole revealed linear calibration functions and, therefore, were suitable for estragole quantitation. In contrast to this, [3′,3′-²H₂]estragole could only be applied as I.S. if it was added to the extracts in stoichiometric deficiency compared to unlabelled estragole. Moreover, due to its different chemical and physical properties, 1,2,4-trimethoxybenzene showed a recovery as low as 77%, whereas the other I.S. revealed recovery rates close to 100%. Considering the “real” values of estragole in fennel tea, the choice of the I.S. obviously is less important than the way of preparing the tea. In contrast to the common method for tea preparation, squeezing of the teabags increased the estragole content significantly by 50%.     

Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant

Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H₂O₂ + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV–Vis–NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H₂O₂ + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant ‘bio-corona’ and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system.     

Comparing alternative cellulosic biomass biorefining systems: Centralized versus distributed processing systems

This study explores how two different cellulosic ethanol production system configurations (distributed versus centralized processing) affect some aspects of the economic and environmental performance of cellulosic ethanol, measured as minimum ethanol selling price (MESP) and various environmental impact categories. The eco-efficiency indicator, which simultaneously accounts for economic and environmental features, is also calculated. The centralized configuration offers better economic performance for small-scale biorefineries, while the distributed configuration is economically superior for large-scale biorefineries. The MESP of the centralized configuration declines with increased biorefinery size up to a point and then rises due to the cost of trucking biomass to the biorefinery. In contrast, the MESP in the distributed configuration continuously declines with increasing biorefinery size due to the lower costs of railroad transportation and the greater economies of scale achieved at much larger biorefinery sizes, including biorefineries that reach the size of an average oil refinery—about 30,000 tons per day of feedstock. The centralized system yields lower environmental impacts for most impact categories than does the distributed system regardless of the biorefinery size. Eco-efficiency analysis shows that the centralized configuration is more sustainable for small-scale biorefineries, while the distributed configuration with railroad transport is more sustainable for large-scale biorefineries. Compared with gasoline from petroleum, cellulosic ethanol fuel offers sustainability advantages for the following environmental impact categories: fossil energy consumption, global warming, human health impacts by particulate matter, ozone layer depletion, ecotoxicity, human health cancer, and human health non-cancer, depending somewhat on the biorefinery sizes and the system configurations.