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

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

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

Activities of the glucoamylase at different temperature.

<p>(A) 30 mg of dialyzed and lyophilized powder was added into 3 mL of 1.0 mg/mL glucoamylase solution to perform the adsorption of enzyme at 60°C for four hours and then at 25°C for one hour. After centrifugation and washing process to remove free enzyme, the sedimentation of CLGNs were incubated at different temperature to determine the activities of released enzyme. The activities of free glucoamylase were also calculated at the same condition for comparison. (B) Comparison of enzyme activities for the released glucoamylase at 60°C and free enzyme at temperature range of 30–85°C a: Data are compared with the data of released enzyme at 40°C and significantly different (<i>P</i><0.05) from that data; b: Data are compared with the data of free enzyme at 85°C and significantly different (<i>P</i><0.05) from that data.</p

TEM image of the CLGNs.

<p>(A) negative stained by phosphotungstic acid and (B) gluocoseamylase immobilized CLGNs prepared by adsorption method.</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

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