On-chip nanoliter-volume multiplex TaqMan polymerase chain reaction from a single copy based on counting fluorescence released microchambers

A novel method for multiplex TaqMan PCR in nanoliter volumes on a highly integrated silicon microchamber array is described. Three different gene targets, related to beta-actin, sex-determining region Y (SRY), and Rhesus D (RhD) were amplified and detected simultaneously on the same chip by using three different types of human genomic DNA as the templates. The lack of cross-contamination and carryover was shown using alternate dispensing of mineral oil-coated microchambers containing template and those without template. To confirm the specificity of our system to beta-actin, SRY, and RhD genes, we employed the larger volume PCR samples to a commercial real-time PCR system, SmartCycler. The samples were cycled with the same sustaining temperatures as with the microchamber array. Instead of the conventional method of DNA quantification, counting the number of the fluorescence released microchambers in consequence to TaqMan PCR was employed to our chip. This simple method of observing the end point signal had provided a dynamic quantitative range. Stochastic amplification of 0.4 copies/reaction chamber was achieved. The microfabricated PCR chip demonstrated a rapid and highly sensitive response for simultaneous multiple-target detection, which is a promising step toward the development of a fully integrated device for the "lab-on-a-chip" DNA analysis.     

Simultaneous determination of residual fourteen kinds of beta-lactam and macrolide antibiotics in bovine muscles by high-performance liquid chromatography with a diode array detector

Residues of 14 kinds of beta-lactam and macrolide antibiotics in bovine muscles were extracted with acetonitrile and the extract was partitioned with n-hexane to remove fat. High-performance liquid chromatography was carried out on a TSK-gel ODS-80TM column using gradient elution with acetonitrile-0.05% trifluoroacetic acid and the drugs were quantitated by diode array detection. The recoveries of the drugs from bovine muscles spiked at 0.1 ppm were over 63% and each quantitation limit was 0.04 ppm.     

Thermal reactions of dipolar trimethylenemethane species

Installation of two alkoxy groups on a terminal methylene of trimethylenemethane (TMM) dramatically alters the electronic state and the reactivities of the TMM. Thermolysis of a 1,1-dialkoxy-2-methylenecyclopropane generates such a TMM, which exhibits a marked singlet dipolar character. It undergoes [3 + 2] cycloadditions to a variety of electron-deficient unsaturated compounds including alkenes, alkynes, oximes, carbonyl compounds, and fullerenes and reacts with active methelene compounds and organozinc reagents as a 1,3-dipolar synthon.     

Damage to and recovery of coastlines polluted with C-heavy oil spilled from the Nakhodka

The damage to and recovery of the Japanese coastline from Suzu, Ishikawa Prefecture to Mikuni, Fukui Prefecture was investigated visually over three years after a C-heavy oil spill from the Russian tanker "Nakhodka" in the Japan Sea on January 2, 1997. The beached C-heavy oil tended to remain for a long time on coasts of bedrock and boulder/cobble/pebble but it was removed rapidly from coasts of gravel/sand and man-made structures such as concrete tetrapods. On the coasts of the latter type, wave energy appeared to be the main force removing the oil. One year after the spill, C-heavy oil tended to remain strongly on the sheltered coasts of bedrock and boulder/cobble/pebble. Even on coasts of this type, the contamination was remarkably absent by 2 years after the spill. The concentration levels of polycyclic aromatic hydrocarbons (PAHs) in oil lumps, sand and seawater were monitored during 3 years following the spill. The concentrations of PAHs having 2 or 3 rings decreased more quickly than did those of PAHs having 4 or more rings, suggesting that volatilization was the main cause of the decrease. On the other hand, the concentrations of PAHs having 4 to 6 rings did not start to decrease until 7 months after the spill. The main cause of the decrease seemed to be photolysis. The concentration of BaP in seawater off the polluted coasts was high 1 month after the spill and then decreased. Three years after the spill, the level fell to the sub ng/L level, which was as low as the level in seawater along unpolluted clean coasts in Japan. The concentration of BaP in greenling was higher than the normal level only during the first two months after the spill. These results suggest that the coastlines in Ishikawa and Fukui Prefectures that were polluted with C-heavy oil recovered in 3 years.     

Influence of morphology on photo‐degradation of low density polyethylene films

The effect of the morphology on photo‐degradation was investigated for low‐density polyethylene materials. For this purpose, films with different degrees of crystallinity and different degrees of orientation were prepared. For all the films, photodegradation was promoted at 336K for 12 days using a weather meter. The following results were obtained. There existed an induction period before degradation or chain scission. The induction period was longer for stretched films than for un‐stretched ones. Also, the rate of degradation became lower for stretched films. However, both the induction period and the rate of degradation hardly changed with heat‐treatment condition, that is, the degree of crystallinity. In the induction period, the density changed in a complicated manner. This complicated change must be due to the change in the molecular aggregation state of the amorphous phase. The rheological and GPC measurements indicated that photo‐degradation causes the lowering of molecular weight and the increase in higher molecular weight fraction, and consequently the broadening of molecular weight distribution. The lowering of molecular weight may be caused by chain scission and the increase in higher molecular weight fraction by the formation of crosslinks.     

Local structure investigations of accumulated damage in irradiated MgAl2O4

Damaged structures in the MgAl₂O₄ spinel induced by swift heavy ions were investigated using the X-ray absorption near edge structure (XANES) and small angle X-ray scattering (SAXS). Increasing the fluence of 100 MeV Xe ions leads to increased SAXS intensity and XANES spectral changes on both Mg and Al K-edges. The damaged regions of ion tracks were observed by SAXS to be cylindrical in shape with a diameter of 5 nm. The theoretical XANES spectra indicated that the changes in the experimental spectra were due to the cationic disordering between tetrahedral and octahedral sites. This disordering caused an increase in the inversion degree of the cations. Furthermore, the quantitative analysis of the XANES spectra revealed the preferential occupation of cations at the octahedral sites at high fluence.     

Effects of injection molding conditions on the electrical properties of polycarbonate/carbon nanotube nanocomposites

Polycarbonate/Carbon nanotube (PC/CNT) nanocomposites containing various CNT contents (0–5 wt%) were prepared by injection molding. The effects of CNT contents, injection speed (V) and injection temperature (T) on the electrical resistivity of the PC/CNT nanocomposites were investigated. It was found that the tensile strength of nanocomposites was enhanced slightly with increased CNT contents, and the tensile modulus was 29% greater after the 5 wt% CNT addition, but the brittle tendency became stronger. Aside from tensile properties, the electrical resistivity of the nanocomposites dropped 12 orders of magnitude after the 5 wt% CNT addition. Also, there was a tendency that the electrical resistivity was lower in the case of higher injection temperature and lower injection speed. Scanning electron microscope (SEM) images and the distribution of surface layer electrical resistivity, clearly showed a notable influence by surface layer microstructures on the electrical resistivity, and the injection conditions affected both the value of the maximum electrical resistivity and the position where it occurred. This study offers an alternative green and simple molding process to prepare conductive PC nanocomposites and to achieve the industrialization of PC/CNT nanocomposite products which can be used in electromagnetic shielding and anti‐static fields. POLYM. COMPOS., 37:3245–3255, 2016. © 2015 Society of Plastics Engineers     

Analysis of spinosad in animal and fishery products by LC-MS

We investigated the determination of spinosyn A and spinosyn D, the active ingredients of spinosad, in animal and fishery products by liquid chromatography with mass spectrometry (LC-MS). The sample was homogenized with 1 mol/L dipotassium hydrogenphosphate aqueous solution and extracted with acetone-n-hexane under mildly alkaline conditions. After n-hexane-acetonitrile partitioning using an EXtrelut(?) column, the extract was cleaned up on a tandem SAX/PSA mini-column, and examined by means of fragmenter-voltage-switching ESI-SIM mode LC-MS. Mean recoveries (n=5) of spinosyn A and spinosyn D from eleven kinds of fortified samples at the analyte concentration of 0.01 μg/g and 0.05 μg/g ranged from 76.1% to 93.8% (RSD≤8.7%) and from 75.1% to 104.1% (RSD≤8.6%), respectively.