Chlorophyll Pigments and Their Synthetic Analogs.

Oxygenic phototrophs use chlorophylls (Chls) as photosynthetically active pigments. A variety of Chl molecules have been found in photosynthetic eukaryotes including green plants, algae, and cyanobacteria. Here we review their molecular structures with stereochemistry, occurrence in light-harvesting antennas and reaction centers, biosyntheses in the late stage, chemical stabilities, and visible absorption maxima in diethyl ether. The observed maxima are comparable to those of semisynthetic Chl analogs, methyl pyropheophorbides, in dichloromethane. The effects of their peripheral substituents and core π-conjugation on the maxima of the monomeric states are discussed. Notably, the oxidation along the molecular x-axis in Chl-a produces its accessory pigments, Chls-b/c, and introduction of an electron-withdrawing formyl group along the y-axis perpendicular to the x-axis affords far-red light absorbing Chls-d/f.

In vitro demetalation of central magnesium in various chlorophyll derivatives using Mg-dechelatase homolog from the chloroflexi Anaerolineae.

In the metabolic pathway of chlorophylls (Chls), an enzyme called STAY-GREEN or SGR catalyzes the removal of the central magnesium ion of Chls and their derivatives to their corresponding free bases, including pheophytins. The substrate specificity of SGR has been investigated through in vitro reactions using Chl-related molecules. However, information about the biochemical properties and reaction mechanisms of SGR and its substrate specificity remains elusive. In this study, we synthesized various Chl derivatives and investigated their in vitro dechelations using an SGR enzyme. Chl-a derivatives with the C3-vinyl group on the A-ring, which is commonly found as a substituent in natural substrates, and their analogs with ethyl, hydroxymethyl, formyl, and styryl groups at the C3-position were prepared as substrates. In vitro dechelatase reactions of these substrates were performed using an SGR enzyme derived from an Anaerolineae bacterium, allowing us to investigate their specificity. Reactivity was reduced for substrates with an electron-withdrawing formyl or sterically demanding styryl group at the C3-position. Furthermore, the Chl derivative with the C8-styryl group on the B-ring was less reactive for SGR dechelation than the C3-styryl substrate. These results indicate that the SGR enzyme recognizes substituents on the B-ring of substrates more than those on the A-ring.

Supramolecular chirality in self-assembly of zinc protobacteriochlorophyll-d analogs possessing enantiomeric esterifying groups.

Zinc 3-hydroxymethyl-pyroprotopheophorbides-a esterified with a chiral secondary alcohol at the 17-propionate residue were prepared as bacteriochlorophyll-d analogs. The synthetic zinc 31-hydroxy-131-oxo-porphyrins self-aggregated in an aqueous Triton X-100 micellar solution to give red-shifted and broadened Soret and Qy absorption bands in comparison with their monomeric bands. The intense, exciton-coupled circular dichroism spectra of their self-aggregates were dependent on the chirality of the esterifying groups. The observation indicated that the self-aggregates based on the J-type stacking of the porphyrin cores were sensitive to the peripheral 17-propionate residues. The supramolecular structures of the present J-aggregates as models of bacteriochlorophyll aggregates in natural chlorosomes were remotely regulated by the esterifying groups.

The role of natural recovery category in malaria dynamics under saturated treatment.

In the process of malaria transmission, natural recovery individuals are slightly infectious compared with infected individuals. Our concern is whether the infectivity of natural recovery category can be ignored in areas with limited medical resources, so as to reveal the epidemic pattern of malaria with simpler analysis. To achieve this, we incorporate saturated treatment into two-compartment and three-compartment models, and the infectivity of natural recovery category is only reflected in the latter. The non-spatial two-compartment model can admit backward bifurcation. Its spatial version does not possess rich dynamics. Besides, the non-spatial three-compartment model can undergo backward bifurcation, Hopf bifurcation and Bogdanov-Takens bifurcation. For spatial three-compartment model, due to the complexity of characteristic equation, we apply Shengjin's Distinguishing Means to realize stability analysis. Further, the model exhibits Turing instability, Hopf bifurcation and Turing-Hopf bifurcation. This makes the model may admit bistability or even tristability when its basic reproduction number less than one. Biologically, malaria may present a variety of epidemic trends, such as elimination or inhomogeneous distribution in space and periodic fluctuation in time of infectious populations. Notably, parameter regions are given to illustrate substitution effect of two-compartment model for three-compartment model in both scenarios without or with spatial movement. Finally, spatial three-compartment model is used to present malaria transmission in Burundi. The application of efficiency index enables us to determine the most effective method to control the number of cases in different scenarios.

The substitution effect of financial and non-financial incentives at different income levels in physician recruitment: evidence from medical students in China.

BACKGROUND: Understanding how medical students respond to financial and non-financial incentives is crucial for recruiting health workers and attracting health talents in medical education. However, both incentives are integrated in working practice, and existing theoretical studies have suggested that various income levels may influence the substitution effect of both incentives, while the empirical evidence is lacking. Furthermore, little attention has been paid to the intrinsic motivation. This study aimed to explore the substitution effect of extrinsic incentives at different income levels, also taking intrinsic altruism into account. METHODS: We used the behavioral data from Zhang et al.'s experiments, which involved discrete choice experiments (DCEs) to assess the job preferences of medical students from six teaching hospitals in Beijing, China. The incentive factors included monthly income, work location, work environment, training and career development opportunities, work load, and professional recognition. Additionally, a lab-like experiment in the medical decision-making context was conducted to quantify altruism based on utility function. Furthermore, we separated the choice sets based on the actual income and distinguished the medical students on altruism. The willingness to pay (WTP) was used to estimate the substitution effect of incentives through conditional logit model. RESULTS: There was a significant substitution effect between non-financial and financial incentives. As income increased, non-financial incentives such as an excellent work environment, and sufficient career development became relatively more important. The impact of the increase in income on the substitution effect was more pronounced among individuals with higher altruism. Concerning the non-financial incentive work environment, in contrast to the growth of 546 CNY (84 USD) observed in the low-altruism group, the high-altruism group experienced a growth of 1040 CNY (160 USD) in the substitution effect. CONCLUSIONS: The increase in the income level exerted an influence on the substitution effect of non-financial incentives and financial incentives, especially in high-altruism medical students. Policymakers should attach importance to a favorable environment and promising career prospects on the basis of ensuring a higher income level. Medical school administrations should focus on promoting altruistic values in medical education, enhancing talent incentives and teaching strategies to encourage medical students to devote themselves to the medical professions.

Green technology innovation under differentiated carbon constraints: The substitution effect of industrial relocation.

The relationship between the carbon intensity constraint policy (CICP) and green technology innovation (GTI) has been well documented in the literature. However, the allocation method of the carbon abatement target is often ignored. The allocation method plays a decisive role in the policy effect. After alleviating the possible endogenous problems through quasi natural experiment, we find that the CICP with the special allocation method promotes GTI in the western provinces but inhibits GTI in the eastern provinces. Especially, the positive impact in the western provinces presents an intensifying trend. To discuss the potential mechanism, we further construct a three-dimensional panel, which contains 1.84 million observations. Our macro and micro evidences reveal that manufacturing firms in the eastern provinces tend to move westward under carbon constraints rather than GTI. In other words, the industrial relocation has a substitution effect on GTI, which further explains why the CICP inhibits GTI in the eastern provinces. The above findings offer targeted policy reference for regulators and government departments concerned with the issues of carbon emission reduction and GTI.

Strongly Bound π-Hole Tetrel Bonded Complexes between H2 SiO and Substituted Pyridines. Influence of Substituents.

Ab initio calculation at the MP2/aug-cc-pVTZ level has been performed on the π-hole based N… Si tetrel bonded complexes between substituted pyridines and H2 SiO. The primary aim of the study is to find out the effect of substitution on the strength and nature of this tetrel bond, and its similarity/difference with the N… C tetrel bond. Correlation between the strength of the N… Si bond and several molecular properties of the Lewis acid (H2 SiO) and base (pyridines) are explored. The properties of the tetrel bond are analyzed using AIM, NBO, and symmetry-adapted perturbation theory calculations. The complexes are characterized with short N… Si intermolecular distances and high binding energies ranging between -142.72 and -115.37 kJ/mol. The high value of deformation energy indicates significant geometrical distortion of the monomer units. The AIM and NBO analysis reveal significant coordinate covalent bond character of the N⋅⋅⋅Si π-hole bond. Sharp differences are also noticed in the orbital interactions present in the N⋅⋅⋅Si and N⋅⋅⋅C tetrel bonds.

Suicide, firearms, and legislation: A review of the Canadian evidence.

Suicide accounts for approximately 4000 deaths a year in Canada, of which about 16% of those are suicide using a firearm. Canada has undertaken legislative efforts to regulate and control firearms, Bill C-51 in 1977 and Bills C-17 and C-68 in 1991 and 1995. Regulatory approaches that decrease the availability of firearms are hypothesized to reduce suicide by firearm however the substitution effect suggests it is possible that people may substitute other methods of suicide in place. Canadian studies on associations between legislation, regulation, and suicide rates have been published over the last three decades, and a search revealed thirteen that met the criteria. Seven studies examined the association between Bill C-51 and suicide rates and found that while rates of suicide by firearm appeared to have declined in association with regulations, there appears to be a substitution effect into other methods and no overall change in suicide rates. Six studies examining the effects of Bill C-17 and C-68 revealed a decrease in the rates of suicide by firearms, with a corresponding increase in non-firearms suicide rates and no decrease in overall suicide rates. One study even suggested no associated decrease in firearm suicide rates with an increasing rate of suicide by hanging possibly due to changes in preferences. These results suggest legislation has mixed effects on firearm suicide rates and may not alone reduce overall suicide in Canada.

In vitro C132-dealkoxycarbonylations of zinc chlorophyll a derivatives including C132-substitutes by a BciC enzyme.

Chlorosomes in the green photosynthetic bacteria are the largest and most efficient light-harvesting antenna systems of all phototrophs. The core part of chlorosomes consists of bacteriochlorophyll c, d, e, or f molecules. In their biosynthetic pathway, a BciC enzyme catalyzes the removal of the C132-methoxycarbonyl group of chlorophyllide a. In this study, in vitro C132-dealkoxycarbonylations of zinc chlorophyll a derivatives bearing a methyl-, ethyl- or propyl-esterifying group and its methyl ester analogs with additional alkyl and hydroxy groups at the C132-position were examined using the BciC enzyme. The BciC-catalyzed reaction activity for the C132-methoxycarbonylated substrate was comparable to that for the ethoxycarbonylated compound; however, depropoxycarbonylation did not proceed. The BciC enzymatic demethoxycarbonylation of zinc methyl C132-alkylated pheophorbides a was gradually suppressed with the elongation of the alkyl chain and finally became inactive for the propyl substrate. The reaction of the C132-hydroxylated substrate (allomer) was accelerated compared to that of the C132-methyl analog possessing a similar steric size, and gave the corresponding C132-oxo product via further air-oxidation. All of the abovementioned enzymatic reactions occurred for one of the C132-epimers with the same configuration as in chlorophyllide a. The above substrate specificities and product distributions indicated the stereochemistry and size of the BciC enzymatic active site (pocket).

A label-free electrochemical assay for coronavirus IBV H120 strain quantification based on equivalent substitution effect and AuNPs-assisted signal amplification.

A label-free electrochemical strategy is proposed combining equivalent substitution effect with AuNPs-assisted signal amplification. According to the differences of S1 protein in various infectious bronchitis virus (IBV) strains, a target DNA sequence that can specifically recognize H120 RNA forming a DNA-RNA hybridized double-strand structure has been designed. Then, the residual single-stranded target DNA is hydrolyzed by S1 nuclease. Therefore, the content of target DNA becomes equal to the content of virus RNA. After equivalent coronavirus, the target DNA is separated from DNA-RNA hybridized double strand by heating, which can partly hybridize with probe 2 modified on the electrode surface and probe 1 on AuNPs' surface. Thus, AuNPs are pulled to the surface of the electrode and the abundant DNA on AuNPs' surface could adsorb a large amount of hexaammineruthenium (III) chloride (RuHex) molecules, which produce a remarkably amplified electrochemical response. The voltammetric signal of RuHex with a peak near - 0.28 V vs. Ag/AgCl is used as the signal output. The proposed method shows a detection range of 1.56e-9 to 1.56e-6 µM with the detection limit of 2.96e-10 µM for IBV H120 strain selective quantification detection, exhibiting good accuracy, stability, and simplicity, which shows a great potential for IBV detection in vaccine research and avian infectious bronchitis diagnosis. Graphical abstract.

Substitution effects on olefin epoxidation catalyzed by Oxoiron(IV) porphyrin π-cation radical complexes: A dft study.

The effects of peripheral fluorine atoms on epoxidation reactions of ethylene by oxoiron(IV) porphyrin cation radical complex in the quartet and sextet spin multiplicities are systematically investigated using the DFT method. The overall reaction routes are determined using a model system of ethylene and Fe(IV)OCl-porphyrin with substituted fluorine atoms. By obtaining the energy diagrams and electron- and spin-density difference contour maps of the transition states and intermediate compounds, we confirm that the electron-withdrawing by peripheral fluorine atoms enhances the reactivity as the number of fluorine atoms increases, as is observed experimentally. The intersystem crossing between the quartet and sextet spin multiplicities is discussed by means of the intrinsic reaction coordinate method. We conclude that the rate-determining step is located at the first transition state (TS1) for the activation of CC and FeO bonds, and the ground electronic state changes from quartet to sextet around the TS1. © 2019 Wiley Periodicals, Inc.

Is There a Woodwork Effect? Addressing a 200-Year Debate on the Impacts of Expanding Community-Based Services.

In U.S. social welfare history, many have suggested that if benefits were too attractive, consumers would come out of the woodwork to take advantage of the opportunity. Clinical trials have provided evidence of the woodwork effect's existence, suggesting caution when expanding home- and community-based services (HCBS). However, it is unclear whether these studies are best suited to assess whether a system-level effect occurs. Using state and federal data tracking Ohio's long-term services and support (LTSS) system from 1995 to 2015, this paper examines changes in the utilization rates and expenditures of Medicaid LTSS to explore whether a woodwork effect occurred as Ohio moved to improve its LTSS system balance (80% Nursing Home [NH], 20% HCBS) to (49% Nursing Home [NH], 51% HCBS). After accounting for population growth of individuals older than 60 and those with two or more impairments in activities of daily living, there was no change in utilization rates of older people with severe disability (1995: 491 per 1000 population, 2015: 495 per 1000 population) or overall LTSS expenditures (1997: $2.7 million [in 2013 dollars], 2013: $2.9 million). Our results suggest that states can make significant strides in HCBS expansion without increasing the overall long-term services utilization rate.

A golden opportunity: benzofuranone modifications of aurones and their influence on optical properties, toxicity, and potential as dyes.

Aurones are a small subclass of the flavonoid family known primarily for their unusual structure and the golden yellow color they impart to the flowers of snapdragons and cosmos. Most studies of aurones focus on their range of biological activities, but relatively little has been reported with respect to their optical properties, unlike their aza and thio analogs. What little is known has focused entirely on the influence of the benzylidene portion. In this study, the influence of substitution in the benzofuranone ring on the UV-vis spectrum is explored, as well as an initial screening of their toxicity and a qualitative preliminary study of their potential to act as fabric dyes.

A push for public health: the effect of e-bikes on physical activity levels.

BACKGROUND: Cycling is considered to have a positive effect on public health through increased physical activity. In Norway, the e-bike is seen as a way of getting more people to cycle. However, the motorized assistance of an e-bike potentially eliminates any physical activity associated with its use. It is possible that the assumed health effect of increased cycling is "erased" through a reduction in other physical activities (a substitution effect). In this paper we study the public health effects of e-bikes using a combined cross-sectional and quasi-experimental design. First, we explore the existence of potentially hedonistic values in relation to interest in acquiring an e-bike and, second, we conduct an intervention study of physical activity pre- and post-purchase. METHODS: A sample of 340 people responded to a questionnaire before buying an e-bike and follow-up 4 weeks later, when 45 had bought one. A further 28 (mainly physically inactive) were recruited through a Norwegian NGO. For a comparison group, 1995 people were recruited through the Falck National Register of Bicycle Owners. All respondents were asked about the intensity of their cycling, (kilometres cycled in the previous week), walking and physical activity in addition to cycling as means of transport (days and hours). RESULTS: A structural equation model showed that hedonistic life values, and general physical activity, were predictive of interest in buying an e-bike. However people who already cycled a lot showed less interest. The trial showed that increased cycling - whether as a mean of transport or exercise -was related to higher levels of total physical activity in both groups compared to a comparison group (one-way ANOVA). CONCLUSIONS: Our findings indicate that in the Norwegian cycle population there is no substantial substitution effect of physical activity with the introduction of an e-bike. The appeal of the e-bike is strongest among those with little existing interest in, or levels of, physical activity. The net effect of the e-bike therefore seems positive from a public health perspective.

Synthesis of chlorophyll-c derivatives by modifying natural chlorophyll-a.

Chlorophyll-a (Chl-a) was extracted from cyanobacterial cells and modified to methyl pyropheophorbide-a. The 3-vinyl-chlorin was transformed to zinc complex of the corresponding 3-acetyl-porphyrin. The zinc porphyrin was oxidized to give cis-7,8- and 17,18-dihydroxy-chlorins as well cis-7,8-cis-17,18-tetrahydroxybacteriochlorin. After zinc-demetallation, the isolated cis-7,8- and 17,18-diols were reduced at the 3-acetyl group and triply dehydrated under acidic conditions to afford two regioisomeric 3-vinyl-porphyrins, methyl divinyl-pyroprotopheophorbide-a possessing the 8-vinyl group and 17-propionate residue (one of the divinyl-protoChl-a derivatives) and methyl pyropheophorbide-c 1 possessing the 8-ethyl group and 17-acrylate residue (one of the Chl-c 1 derivatives), respectively. The resulting 7,8,17,18-tetrol was reduced and then acidically treated, giving five-fold dehydrated free base porphyrin, methyl pyropheophorbide-c 2 possessing the 3,8-divinyl groups and 17-acrylate residue (one of the Chl-c 2 derivatives). The visible absorption and fluorescence emission spectra of the three semi-synthetic 3-vinyl-porphyrins in dichloromethane were compared with those of the corresponding 8-ethyl-porphyrin bearing the 17-propionate residue, methyl pyroprotopheophorbide-a (one of the protoChl-a derivatives). The Soret and Qy absorption maxima were shifted to longer wavelengths with an increase of π-conjugation in a molecule: protoChl-a (8-CH2CH3/17-CH2CH2COOCH3) < divinyl-protoChl-a (8-CH=CH2/17-CH2CH2COOCH3) < Chl-c 1 (8-CH2CH3/17-CH=CHCOOCH3) < Chl-c 2 derivatives (8-CH=CH2/17-CH=CHCOOCH3). The 17(1),17(2)-dehydrogenation broadened the absorption bands. The emission maxima were bathochromically shifted in the same order. The reaction mechanism of the present dehydration indicates that the biosynthetic pathway of Chls-c would include the hydroxylation of the 17-propionate reside at the 17(1)-position and successive dehydration to the 17-acrylate residue.

A CASSCF/CASPT2 insight into excited-state intramolecular proton transfer of four imidazole derivatives.

Excited-state intramolecular proton transfer (ESIPT) of four imidazole derivatives, 2-(2'-hydroxyphenyl)imidazole (HPI), 2-(2'-hydroxyphenyl)benzimidazole (HPBI), 2-(2'-hydroxyphenyl)-1H-phenanthro[9,10-d]imidazole (HPPI) and 2-(2'-hydroxyphenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (HPPPI), were studied by the sophisticated CASSCF/CASPT2 methodology. The state-averaged SA-CASSCF method was used to optimize their geometry structures of S0 and S1 electronic states, and the CASPT2 calculations were used for the calibration of all the single-point energies, including the absorption and emission spectra. A reasonable agreement is found between the theoretical predictions and the available experimental spectral data. The forward ESIPT barriers of four target compounds gradually decrease with the increase of molecular size. On the basis of the present calculations, it is a plausible speculation that the larger the size, the faster is the ESIPT rate, and eventually, HPPPI molecule can undergo a completely barrierless ESIPT to the more stable S1 keto form. Additionally, taking HPI as a representative example, the radiationless decays connecting the S0 and S1 /S0 conical intersection structures were also studied by constructing a linearly interpolated internal coordinate (LIIC) reaction path. The qualitative analysis shows that the LIIC barrier of HPI in the keto form is remarkably lower than that of its enol-form, indicating that the former has a big advantage over the latter in the nonradiative process.

Synthesis of chlorophyll-f analogs possessing the 2-formyl group by modifying chlorophyll-a.

A methyl group at the 2-position of methyl mesopyropheophorbide-a was transformed to the 2-formyl group to give methyl mesopyropheophorbide-f, one of the chlorophyll-f analogs. The 2-formylation moved the redmost electronic absorption band in a solution to a longer wavelength and the bathochromic shift was comparable to that by the 3-formylation. Zinc complex of the synthetic compound in solutions showed similar visible absorption spectra as those of naturally occurring chlorophyll-f.

Self-aggregation of zinc bacteriochlorophyll-d analogs with an acylhydrazone moiety as the 13-keto-carbonyl alternative.

Zinc methyl 3-hydroxymethyl-pyropheophorbides-a possessing an acylhydrazinylidene group at the 131-position were prepared by chemically modifying chlorophyll-a, which were models of bacteriochlorophyll-d as one of the light-harvesting pigments in photosynthetic green bacteria. Similar to the self-aggregation of natural bacteriochlorophyll-d in the antenna systems called chlorosomes, some of the synthetic models self-aggregated in an aqueous Triton X-100 solution to give red-shifted and broadened visible absorption bands. The newly appeared oligomeric bands were ascribable to the exciton coupling of the chlorin π-systems along the molecular y-axis, leading to intense circular dichroism bands in the red-shifted Qy and Soret regions. The self-aggregation in the aqueous micelle was dependent on the steric size of the terminal substituent at the 13-acylhydrazone moiety. An increase in the length of the oligomethylene chain as the terminal moved the red-shifted Qy maxima to shorter wavelengths, and branched alkyl and benzyl substitutes afforded no more self-aggregates to leave monomeric species in the hydrophobic environment inside the micelle. These results indicated that the acyl groups on the 13-hydrazone as the alternative of the natural 13-ketone regulated the chlorosome-like self-aggregation.

Artificial intelligence and labor demand: An empirical analysis of Chinese small and micro enterprises.

The widespread application of artificial intelligence (AI) technology has triggered a significant transformation in the economic structure and has brought profound changes to human society. As China promotes the digital transformation of industries, understanding how the investment in AI by small and micro enterprises (SMEs) affects labor demand, which is inextricably linked to "stable employment", becomes an important question. This paper uses special data from 127 SMEs in 14 provinces from 2016 to 2020 and employs a two-way fixed effects model to study the impact of AI inputs on enterprises' labor demand. The empirical results show that the impact of AI inputs on the labor demand of SMEs is not significant overall, but shows a significant negative effect in non-state-owned enterprises, private enterprises, and high-tech enterprises. There is a significant difference in the impact of AI inputs on the labor demand of different industries, with only the wholesale and retail industry demonstrating a significant positive impact. From the results of mechanism analysis, the substitution effect and creation effect of AI inputs on labor demand coexist, and in general, these two effects cancel each other out. However, the substitution effect dominates in some types of enterprises and industries. Finally, this paper discusses the government and enterprise coping strategies for the employment impact of AI applications based on empirical evidence and research results. This paper not only theoretically demonstrates that the impact of AI investment on firms' labor demand is uncertain, but also empirically demonstrates that Chinese firms' AI investment does not significantly affect firms' overall labor demand. This facilitates the government and enterprises to formulate strategies that can enhance the level of enterprise intelligence without impacting the labor market.

Environmental regulation and labor demand: Evidence from China's air pollution prevention and Control Action Plan.

In response to environmental regulatory pressure from the government, enterprises - as the main employers of labor - adjust their production-related choices and may alter their demand for labor. Numerous researches have probed into how environmental regulations affect the labor demand, which has emerged as a significant concern in the discourse around the adoption of environmental regulation policies. Nonetheless, many researches predominantly concentrates on the evaluation on the effects of environmental regulations on economic and environmental levels. Moreover, rare attention has been paid to how environmental regulations affect social activities, especially in terms of labor demands. As a result, the Air Pollution Prevention and Control Action Plan (APPCAP) is adopted as a "quasi-natural experiment" and a difference-in-differences model is employed to analyze the effects of the APPCAP on labor demands of companies. Hence, the 2008-2020 panel data are considered for the 3,949 Chinese A-share listed enterprises. Furthermore, this paper probes deeply into the underlying mechanisms based on mediation models. The following findings are thus concluded: (1) The labor demands of enterprises can be remarkably increased by APPCAP; and the result is still persuasive even though the endogeneity issues are taken into account. (2) APPCAP improves enterprise labor demand through the output and factor substitution effects. (3) As evidently revealed by heterogeneity analysis, the APPCAP could significant positive affect the labor demand size in state-owned companies, large-scale companies, new companies, and companies in polluting industries. (4) The APPCAP strikingly boosts the demand for labor force with high skills. Nevertheless, it exerts little influence on the demand for labor force with low skills and company salary levels. Therefore, the government must continue to steadfastly implement environmental regulatory policies but adopt different policies based on enterprise characteristics. Overall, this study provides micro-level experimental evidence for more in-depth understanding of how environmental policies affect labor market, which is particularly important for actively resolving social employment problems and exploring new growth points in enterprise employment.