[en] A novel and highly sensitive chemiluminescence (CL) method for the determination of dicyandiamide (DCD) has been developed based on the new CL system of N-bromosuccinimide–merbromin–cetyltrimethylammonium bromide in alkaline solution. Experiment conditions were optimized using central composite design-response surface methodology. Under the optimal conditions, the relative CL intensity was linear with the concentration of DCD ranging from 5.0×10⁻⁸ g mL⁻¹ to 3.0×10⁻⁶ g mL⁻¹. The detection limit, at the signal-to-noise ratio of 3, was 3.0×10⁻⁹ g mL⁻¹. The relative standard deviation was 1.9% for 11 repeated determinations of 1.0×10⁻⁶ g mL⁻¹ DCD. The proposed method was successfully applied to the analyses of DCD in tap water and milk products. And the recoveries were in the range of 87.0–102.3% with relative standard deviation values of 1.2–2.9%. Moreover, the minimum sampling rate was 120 samples h⁻¹. The possible mechanism of the CL reaction was also discussed. - Highlights: • A novel NBS–merbromin–CTAB–dicyandiamide CL system was proposed. • A CL method for detection of dicyandiamide was developed. • Chemical parameters were optimized using central composite design. • The proposed method is simple, rapid, sensitive, and low-cost

[en] In this research, an ultrasensitive, rapid and novel flow injection chemiluminescence (FI-CL) strategy has been validated for the determination of hydroquinone (HQ). It was found that the CL intensity of the luminol-hydrogen peroxide system could be enhanced sharply by Jacobsen's catalyst in alkaline solution and the joining of HQ was found to restrain the CL signal of the luminol-hydrogen peroxide reaction catalyzed by the Jacobsen's catalyst, which made it possible for the determination of HQ. Possible mechanism and series of instrumental and chemical arguments were discussed in detail. Under the selected experimental conditions, the relative CL intensity was linear with the concentration of HQ ranging from 6.0×10⁻¹⁰ to 1.0×10⁻⁸ g/mL. The detection limit, at the signal-to-noise ratio of 3 (3σ), was 1.0×10⁻¹⁰ g/mL. The relative standard deviation (RSD) for 2.0×10⁻⁹ g/mL HQ was 2.7% (n=11). The presented CL methodology has been applied for the determination of HQ in water samples with satisfactory results. -- Highlights: ●Jacobsen's catalyst could enhance the CL of luminol-H₂O₂ system in NaOH. ●The possible enhancement mechanism was investigated. ●Detection of hydroquinone in water samples

[en] Objective: To describe the high-resolution CT (HRCT) findings of arc-welders with early pneumoconiosis and to evaluate manifestation in different course of disease. Methods: Seventy-six arc- welders with a one to thirty-eight (mean, 14) years history of exposure underwent CT and HRCT scanning. The extent of abnormalities were detected. The relations of age and year history of exposure were analysed in different groups. Results: Thirty-eight welders (38/76, 50%) showed positive characteristic findings with conventional CT. Predominant thin-section CT findings were poorly-defined centrilobular micronodules (18/76,23.7%), branching linear structure (20/76, 26.3%). The mean age in group of branching linear structure [(39±9) years old] was elder than of poorly-defined centrilobular micronodules [(34±7) years old]. There was no statistical difference between the two groups (t=-1.648, P>0.05). The mean length of service at exposure in group of branching linear structure [(15±8) years] was longer than of poorly-defined centrilobular micronodules [(10±5) years]. And the significant differences were showed between the two groups in the year history of exposure (t=-2.108, P<0.05). Conclusions: Poorly defined centrilobular micronodules and branching linear structures were the thin-section CT findings most frequently seen in patients with arc-welders pneumoconiosis and the former may be one early stage characteristic finding of arc-welders pneumoconiosis. HRCT is useful in achieving more accurate categorization of the parenchymal changes in arc-welders pneumoconiosis. (authors)

[en] Highlights: • The relationship between finance pressure and energy intensity is explored. • Mitigation of finance pressure contributes to the reduction of energy intensity. • Environmental regulation pushes firms to invest in energy-efficiency technologies. • Without environmental regulation, firms invest in energy-intensive technologies. The purpose of this research is to explore the relationship between finance pressure and energy intensity using a firm-level data of Chinese manufacturing sectors. We introduce environmental regulation to our model to identify the technological channel through which finance pressure influence energy intensity. Our findings show that mitigation of finance pressure makes significant contribution to the reduction of energy intensity. As for the technological channel, environmental regulation plays a key role in pushing firms to invest in energy-efficiency technologies when funds are available. On the contrary, absence of environmental regulation would lead to investment in technologies that increase energy intensity. These finding are robust to different proxies for finance pressure and technology investment. Moreover, there are heterogeneous effects across regions and firms. In particular, firms in the eastern provinces and firms of non-foreign ownership are more likely to invest in energy-efficiency technologies when facing environmental regulation. These findings suggest financial policies and measures coordinate with environment and energy policies to make technological progress energy-efficiency oriented.

[en] We show that the anisotropic gap in the CuO₂ plane of high-T_c cuprates is s'+id', s' and d' being the extended s-wave and d-wave, respectively, and the maximum value of the gap is at the angle Φ=12.2 at any fixed temperature, Φ being the angle from the Cu-O bond in the CuO₂ plane. Because the corresponding experimental maximum value is at Φ≅13 as well, it may be possible that the high T_c in the cuprates is due mainly to the two-local-spin-mediated interaction. (orig.)