Role of Organic Carbon in Heterogeneous Reaction of NO₂ with Soot

A large uncertainty among the reported uptake coefficients of NO₂ on soot highlights the importance of the composition of soot in this reaction. Soot samples with different fractions of organic carbon (OC) were prepared by combusting <i>n</i>-hexane under controlled conditions. The heterogeneous reaction of NO₂ on soot was investigated using a flow tube reactor at ambient pressure. The soot with the highest fuel/oxygen ratio showed the largest uptake coefficient (γ_initial) of NO₂ and yield of HONO (<i>y</i>_HONO). Compared to fresh soot samples, preheated samples exhibited a great decrease in uptake coefficient of NO₂ and HONO yield due to the removal of OC from soot. Ozonized soot also showed a lower reactivity toward NO₂ than fresh soot, which can be ascribed to the consumption of OC with a reduced state (OC_R). A linear dependence of the NO₂ uptake coefficient and yields of HONO and NO on the OC_R content of the soot was established, with γ_initial(NO₂) = (1.54 ± 1.39) × 10^–6 + (1.96 ± 0.35) × 10^–7 × OC_R, <i>y</i>_HONO = (11.6 ± 16.1) + (1.3 ± 0.40) × OC_R, and <i>y</i>_NO = (13.1 ± 1.9) – (0.2 ± 0.05) × OC_R, respectively

Heterogeneous Uptake of Amines by Citric Acid and Humic Acid

Heterogeneous uptake of methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA) onto citric acid and humic acid was investigated using a Knudsen cell reactor coupled to a quadrupole mass spectrometer at 298 K. Acid–base reactions between amines and carboxylic acids were confirmed. The observed uptake coefficients of MA, DMA, and TMA on citric acid at 298 K were measured to be 7.31 ± 1.13 × 10^–3, 6.65 ± 0.49 × 10^–3, and 5.82 ± 0.68 × 10^–3, respectively, and showed independence of sample mass. The observed uptake coefficients of MA, DMA, and TMA on humic acid at 298 K increased linearly with sample mass, and the true uptake coefficients of MA, DMA, and TMA were measured to be 1.26 ± 0.07 × 10^–5, 7.33 ± 0.40 × 10^–6, and 4.75 ± 0.15 × 10^–6, respectively. Citric acid, having stronger acidity, showed a higher reactivity than humic acid for a given amine; while the steric effect of amines was found to govern the reactivity between amines and citric acid or humic acid

Table1_Study on the impact of regional carbon emissions on enterprise technological innovation under the background of low-carbon transformation in China.DOCX

Low-carbon transition, as the backbone of corporate innovation drive, has an important strategic position globally. In order to avoid heterogeneous intercepts related to explanatory variables or interfering with each other, this paper empirically examines the impact of regional carbon emissions on corporate technological innovation and its mechanism based on the data of listed companies in China from 2009 to 2020, using a fixed-effects model. It is found that 1) the reduction of regional carbon emissions is favourable to corporate technological innovation; 2) in terms of the impact mechanism, the reduction of regional carbon emissions promotes corporate technological innovation by enhancing R&D investment and reducing financing constraints. 3) Based on the study of heterogeneity, it is found that: from the perspective of spatial distribution, regional carbon emissions show the phenomenon of “high on both sides and low in the middle”; state-owned enterprises refer to wholly state-owned enterprises, wholly state-owned companies and state-owned capital holding companies in which the State Council and the local people’s governments respectively perform the responsibilities of funders on behalf of the state. In terms of the nature of equity, compared with state-owned enterprises, regional carbon emissions have a greater impact on the technological innovation of non-state-owned enterprises. 4) Further analysis reveals that the low-carbon city pilot policy is conducive to regional carbon emission reduction. Through the comparison before and after the implementation of low carbon policy, this paper reliably verifies that the introduction of urban carpet policy is conducive to regional carbon emissions, and explores the issue of enterprise technological innovation from the perspective of low carbon transformation, providing theoretical support for the carbon emission reduction efforts and the improvement of the technological innovation capacity of different enterprises. At the same time, it fully affirmed the important role of regional carbon emissions, continued to deepen the process of green transformation of enterprises, and boosted the high-quality development of low-carbon enterprises.</p

Significant Promotion of Light Absorption Ability and Formation of Triplet Organics and Reactive Oxygen Species in Atmospheric HULIS by Fe(III) Ions

Metal ions are key components in atmosphere that potentially affect the optical properties and photochemical reactivity of atmospheric humic-like substances (HULIS), while this mechanism is still unclear. In this study, we demonstrated that atmospheric HULIS coupled with Fe3+, Cu2+, Zn2+, and Al3+ exhibited distinct optical properties and reactive intermediates from that of HULIS utilizing three-dimensional fluorescence spectroscopy and electron paramagnetic resonance spectroscopy. The HULIS components showed light absorption that increased by 56% for the HULIS-Fe3+ system, fluorescence blue shift, and fluorescence quenching, showing a certain dose–effect relationship. These are mainly attributed to the fact that the highly oxidative HULIS chromophores have a stronger complexing ability with Fe3+ ions than the other metal ions. In addition, triplet organics (promoting ratio: 53%) and reactive oxygen species (promoting ratio: 82.6%) in the HULIS-Fe3+ system showed obvious generation promotion. Therefore, the main assumption of the photochemical mechanisms of atmospheric HULIS in the HULIS-Fe3+ system is that Fe3+ ions can form 3HULIS*-Fe3+ complexation with photoexcited 3HULIS* and then transition to the ground state through energy transfer, electron transfer, or nonradiative transition, accompanied by the formation of singlet oxygen and hydroxyl radicals. Our results provide references for evaluating the radiative forcing and aging effect of metal ions on atmospheric aerosols

Temperature responses effect of CLGNs.

<p>(A) Pictures of CLGNs at different temperatures. (B) Size distribution of CLGNs at different temperatures measured using DLS. (C) Size changes of CLGNs at 25°C and 45°C within three cycles.</p

Schematic illustrations for the preparation of CLGNs, glucoamylase immobilization, and temperature-triggered enzyme release.

<p>The gelatin and glucoamylase were mixed together before the cross-linking step in the entrapment method. In the adsorption method, the enzyme was adsorbed after the formation of the CLGNs.</p

Characterization of CLGNs.

<p>(A) Zeta potential measurements values of the CLGNs under different temperature. (B) IR spectra of lyophilized CLGNs. Spectra of pure gelatin were also presented for comparison.</p

Temperature-Sensitive Response for Different Anions Modified CLGNs.

<p>The concentrations of these series sodium solutions with different anions for the CLGNs surface modification were dependent on the charge number of the anions to obtain the same ionic strengths.</p

Glucoamylase Immobilization Efficiency by Adsorption Method Using Dialyzed and Non-dialyzed CLGNs at Different Temperature.

a<p>Data is significantly different (<i>P</i><0.05) from the data of at 25°C;</p>b<p>Data is significantly different (<i>P</i><0.05) from the data at 37°C.</p

Photocatalytic Removal of NO_<i>x</i> over Visible Light Responsive Oxygen-Deficient TiO₂

Oxygen-deficient TiO2 was prepared with a low-temperature method and utilized in photocatalytic removal of gaseous NO at the 400 ppbv level in air under visible light (420 nm < λ < 700 nm) irradiation. Catalysts synthesized at 200 °C (TiO2-200) exhibited the highest ability to remove the NO gas in air under visible light irradiation. A higher oxidation ability for NO2 to NO3– leads to a higher conversion of NOx on TiO2-200. The relationship between the physicochemical properties and the photocatalytic performance of the as-prepared catalyst is discussed. The large surface area of TiO2-200 can provide more active sites for the reaction. The oxygen vacancies of TiO2-200 can effectively expand the absorption of visible light and accelerate the separation of photogenerated electrons and holes. The first-principles density functional theory (DFT) calculation further confirms the role of oxygen vacancies on the narrowing of the band gap and separating of photogenerated electron–hole pairs