Atmospheric Vapor Research Articles

Comparing Machine Learning Algorithms for Estimating the Maize Crop Water Stress Index (CWSI) Using UAV-Acquired Remotely Sensed Data in Smallholder Croplands

Monitoring and mapping crop water stress and variability at a farm scale for cereals such as maize, one of the most common crops in developing countries with 200 million people around the world, is an important objective within precision agriculture. In this regard, unmanned aerial vehicle-obtained multispectral and thermal imagery has been adopted to estimate the crop water stress proxy (i.e., Crop Water Stress Index) in conjunction with algorithm machine learning techniques, namely, partial least squares (PLS), support vector machines (SVM), and random forest (RF), on a typical smallholder farm in southern Africa. This study addresses this objective by determining the change between foliar and ambient temperature (Tc-Ta) and vapor pressure deficit to determine the non-water stressed baseline for computing the maize Crop Water Stress Index. The findings revealed a significant relationship between vapor pressure deficit and Tc-Ta (R2 = 0.84) during the vegetative stage between 10:00 and 14:00 (South Africa Standard Time). Also, the findings revealed that the best model for predicting the Crop Water Stress Index was obtained using the random forest algorithm (R2 = 0.85, RMSE = 0.05, MAE = 0.04) using NDRE, MTCI, CCCI, GNDVI, TIR, Cl_Red Edge, MTVI2, Red, Blue, and Cl_Green as optimal variables, in order of importance. The results indicated that NIR, Red, Red Edge derivatives, and thermal band were some of the optimal predictor variables for the Crop Water Stress Index. Finally, using unmanned aerial vehicle data to predict maize crop water stress index on a southern African smallholder farm has shown encouraging results when evaluating its usefulness regarding the use of machine learning techniques. This underscores the urgent need for such technology to improve crop monitoring and water stress assessment, providing valuable insights for sustainable agricultural practices in food-insecure regions.

Multi-decadal Changes of the Impact of El Niño Events on Tibetan Plateau Summer Precipitation

Precipitation on the Tibetan Plateau (TP) has an important effect on the water supply and demand of the downstream population. Involving recent climate change, the multi-decadal variations of the impact of El Niño-Southern Oscillation (ENSO) events on regional climate were observed. In this work, the authors investigated the changes in summer precipitation over TP during 1950–2019. At the multi-decadal scale, the authors found that the inhabiting impact of El Niño events on the TP summer precipitation has strengthened since the late 1970s. The main factor contributing to this phenomenon is the significant amplification in the decadal amplitude of El Niño during 1978–2019 accompanied by a discernible escalation in the frequency of El Niño events. This phenomenon induces anomalous perturbations in sea surface temperatures (SST) within the tropical Indo-Pacific region, consequently weakening the atmospheric vapor transport from the western Pacific to the TP. Additionally, conspicuous anomalies in subsidence motion are observed longitudinally and latitudinally across the TP which significantly contributes to a curtailed supply of atmospheric moisture. These results bear profound implications for the multi-decadal prediction of the TP climate.

Effects of site aridity and species on stand transpiration in high-elevation dryland ecosystems

Climate change is altering regional aridity and species composition in dryland ecosystems. Understanding the effects of long-term increasing aridity and species-specific stomatal behaviors on transpiration is therefore important for water-resource forecasting. To assess the effects of site aridity levels and species on stand transpiration rate (Es), we monitored sap flux density (Js) and relevant environmental parameters for 16 isohydric Picea crassifolia (spruce) and 14 anisohydric Juniperus przewalskii (juniper) trees over three growing seasons at four arid to semi-arid high-elevation sites on the Tibetan Plateau. Our results show that Es was about 5–9 times higher in semi-arid sites than in arid sites, and about 6–9 times higher in spruce than in juniper. Spruce exhibited stronger stomatal regulation of transpiration than juniper. Soil water supply strongly promoted Js only for spruce in the arid environment (R2 = 0.23), while at the other sites, Js was mostly controlled by atmospheric vapor pressure deficit (VPD) (R2 > 0.82). However, increasing site aridity greatly reduced the sensitivities of both Js and canopy conductance to VPD, especially for juniper. We expect that in the transition from semi-arid to arid alpine forests, Es will initially rise due to increasing VPD. However, in the long term, there may be a stronger decline in Es since both the sensitivity of Js to VPD and the stand sapwood area will decrease. These findings could be used to reduce the impacts of climate change on water resources in high-elevation drylands.

Improved water vapor corrosion resistance of SiC bricks via in situ formation of microporous Yb2Si2O7 bonding phase

AbstractSiC‐based lining refractories used in incinerators faced serious hot water vapor corrosion. The pores in SiC‐based refractories played a crucial role in corrosion resistance because both the penetration of water vapor and the expulsion of corrosion products depended on diffusion channels provided by pores. The in situ microporous Yb2Si2O7 bonding phase formed in the SiC bricks after sintering at 1550°C under air atmosphere, which simultaneously decreased the apparent porosity and pore size. The optimization of pore structures reduced the permeability to gases of SiC bricks by 37.5%, which prevented the penetration of hot water vapor into SiC bricks. The microporous Yb2Si2O7‐bonded SiC bricks presented only .15% permanent linear change and showed good thermal shock resistance after corrosion at 1000°C for 100 h under hot water vapor atmosphere. Some SiC particles in the refractories could be adopted as high‐temperature pore‐forming agents; the gaseous oxidation products of SiC bricks, including SiO(g) and CO(g), contributed to the generation of microporous Yb2Si2O7 (pore size ≤5 μm) and SiC whiskers during sintering, which obviously improved mechanical properties and water vapor corrosion resistance of SiC bricks.

Identifying the Moisture Sources in Different Seasons for Abaya-Chamo Basin of Southern Ethiopia Using Lagrangian Particle Dispersion Model

Understanding the sources of precipitation and their impacts is crucial for basin-wide water balance research. Previous research concentrated on the sources of moisture in Ethiopia. The southern part’s moisture sources, however, were not investigated. The primary objective of this study is to trace the source of atmospheric moisture in the Abaya-Chamo sub-basin of southern Ethiopia using numerical water vapor tracers like Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. Exploring the possible regions of atmospheric vapor roots and the path of moist air initiating rainfall that reaches the basin was feasible for the year 2018–2020. The anticyclone from the Arabian High, which is positioned in the Arabian and Mediterranean seas, was the primary source of moisture supply in the study area during the Belg (March to May) season, according to the back trajectory cluster analysis results. Additionally, the Indian Ocean adds moisture resulting from Mascarene highs brought by equatorial easterlies. Furthermore, during Kiremt (June to September), air masses from the Congo basin were the potential moisture source region for the study areas in combination with air masses originating from the Mascarene highs, located in the South Indian Ocean, and the St. Helena high, centered in the subtropical southern Atlantic Ocean. This study primarily focuses on the complex dynamics of atmospheric moisture sources around Abaya-Chamo sub-basin of southern Ethiopia, offering insight into seasonal fluctuations and contributing various components. These findings contribute to basin-specific water balance research by filling gaps in the previous studies.

Fog harvesting on micro-structured metal meshes: Effect of surface ageing

Access to clean drinking water is a critical need for human societies. Intercepting atmospheric fog can help collect water from the atmosphere, even in situations of high-water scarcity in fog-prone areas. Metal meshes or screens are commonly used as fog collectors, where the mesh surfaces are often engineered to enhance water collection rates. Despite significant work over the past several decades, the ideal surface wettability desired in terms of surface roughness and functionalization for efficient fog harvesting is not well understood. The volume of water collected depends on the proportion of fog intercepted by the meshes and how effectively the deposited water droplets drain off into the collector. In this work, we employ scalable surface treatments such as chemical etching and atmospheric pressure vapor deposition on stainless steel meshes to alter the surface wettability. We evaluate the efficacy of fog harvesting on the wettability altered meshes, and compare their performance against untreated stainless steel meshes. We further investigate the effect of surface ageing on the wettability and fog collection performance. Our work not only offers valuable design guidelines for the development of effective fog collectors but also highlights the significant influence of the atmosphere in controlling wetting behaviour.

Stable isotopic compositions and controlling factors of precipitation and atmospheric vapour in the headwaters of the Shule River

AbstractStable isotopic compositions of precipitation (δ18Op, δ2Hp and d‐excessp) and atmospheric vapour (δ18Ov, δ2Hv and d‐excessv) with high spatial–temporal resolution are crucial in revealing hydrologic cycle. Based on the variation characteristics of δ18Op/δ18Ov, δ2Hp/δ2Hv and d‐excessp/d‐excessv in the headwaters of the Shule River (HSR) on hourly and daily scales from June to September 2018, this study analysed the relationships between δ18Op/δ2Hp and δ18Ov/δ2Hv combined with the equilibrium fractionation model, as well as δ18Op/δ18Ov and meteorological factors. The slopes of local meteoric water line (LMWL) and the δ2Hv‐δ18Ov fitting equation were similar (7.96 and 7.94) with both intercepts exceeding 10, reflecting the great contribution of recycling moisture. The values of δ18Ov/δ2Hv were lower than δ18Op/δ2Hp but with consistent variation patterns throughout the period. The equilibrium simulation results suggested that precipitation and atmospheric vapour almost approached isotopic equilibrium state, especially during monsoon intrusion period. Affected by monsoon intrusion, the slopes and intercepts of the LMWLs and the δ2Hv‐δ18Ov fitting equations were smaller than those during non‐monsoon period and d‐excess and δ18O were negatively correlated. Relative humidity had significant negative correlations with δ18Op and δ18Ov in the whole period, however, the positive correlations between δ18Op/δ18Ov and temperature were observed during non‐monsoon and monsoon intrusion period, respectively. Our results demonstrated that precipitation and atmospheric vapour isotopic compositions exhibited consistency under the influence of diverse moisture sources, while more complex relationships were found between δ18Op/δ18Ov and meteorological factors. This research provided evidence for using the isotopic compositions of atmospheric vapour to indicate moisture sources, and can improve understanding of the water cycle and eco‐hydrological process from the perspective of the interaction between water and gas phases of the inland river basin in northwest China.

A millimeter water-in-oil droplet as an alternative back exchange prevention strategy for hydrogen/deuterium exchange mass spectrometry of peptides/proteins.

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a versatile bioanalytical technique for protein analysis. Since the reliability of HDX-MS analysis considerably depends on the retention of deuterium labels in the post-labeling workflow, deuterium/hydrogen (D/H) back exchange prevention strategies, including decreasing the pH, temperature, and exposure time to protic sources of the deuterated samples, are widely adopted in the conventional HDX-MS protocol. Herein, an alternative and effective back exchange prevention strategy based on the encapsulation of a millimeter droplet of a labeled peptide solution in a water-immiscible organic solvent (cyclohexane) is proposed. Cyclohexane was used to prevent the undesirable uptake of water by the droplet from the atmospheric vapor through the air-water interface. Using the pepsin digest of deuterated myoglobin, our results show that back exchange kinetics of deuterated peptides is retarded in a millimeter droplet as compared to that in the bulk solution. Performing pepsin digestion directly in a water-in-oil droplet at room temperature (18-21 °C) was found to preserve more deuterium labels than that in the bulk digestion with an ice-water bath. Based on the present findings, it is proposed that keeping deuterated peptides in the form of water-in-oil droplets during the post-labelling workflow will facilitate the preservation of deuterium labels on the peptide backbone and thereby enhance the reliability of the H/D exchange data.

Background vapor effect on droplet evaporation in a turbulent flow at elevated pressure

Investigation of the evaporation of single droplets holds a significant importance as it emulates the diluted spray region and helps improve the accuracy of numerical modelling. In the present study, a fan-stirred spherical chamber was employed to generate a homogeneous and isotropic turbulent flow field with negligible mean velocity. This setup was used to investigate the effect of background vapor on the vaporization of a 500 µm pentane droplet in a turbulent flow at elevated pressure and room temperature. Turbulence intensity and pressure were varied, respectively, from stagnant to 1.5 m/s and from 1 to 5 bar. Additionally, the background pentane vapor was altered (on molar basis) from 0 % up to 40 %. The results show that the d2-law is valid throughout all explored test conditions, including in the presence of background vapor. The findings indicated that the presence of background vapor around the evaporating droplet diminishes the droplet vaporization rate under both stagnant and turbulent flow scenarios, with a more pronounced impact at elevated pressure conditions. Furthermore, turbulence is observed to enhance the vaporization rate in the presence of background vapor, with its influence being more substantial at elevated pressure levels and higher concentrations of background vapor. Finally, the experimental data was used to correlate the coupled effect of ambient background vapor, turbulence, and pressure on the vaporization of a pentane droplet in terms of the flow turbulent Reynolds number.

Recycling Glass Fiber from Polyurethane Composite by Pyrolysis Strategy with High Mechanical Properties

With the rapid advancement of the wind power industry, the recycling of retired wind turbine blades and the regeneration of glass fibers have become urgent environmental and economic issues. In this article, a two-step pyrolysis strategy was put forward, in which the relationship between the pyrolysis parameters and the properties of the recycled glass fibers, including the surface morphology, defects, and mechanical properties were demonstrated. We found that pyrolyzing the composites at 500°C under high-temperature water vapor atmosphere to recover the glass fibers, and oxidizing at 450°C to remove the residual carbon of fibers is the optimal choice. In this way, not only can the fibers be recovered from the waste composites, but also the mechanical properties of the fibers can be retained while removing the residual carbon on the surface, which provides a guarantee for subsequent high-value reuse of waste fan blade composite materials.

Synthesis of a highly conductive coordination polymer film via a vapor-solid phase chemical conversion process.

A novel vapor-solid phase chemical conversion process is reported here to synthesise high-quality films of the conductive coordination polymer (c-CP) Ag5BHT (BHT = benzenehexanothiolate), which has the potential to be applied for the synthesis and processing of c-CP electronic devices. This approach involves reacting a silver oxide precursor and an H6BHT linker in an isopropanol solvent vapor atmosphere to obtain Ag5BHT thin films with controllable thickness (100-300 nm). The as-synthesized Ag5BHT thin films exhibit conductivities as high as 10 S cm-1. Additionally, under field-effect modulation, these nanofilms demonstrate remarkably high charge mobility (38 cm2 v-1 s-1).

Water content of rocky exoplanets in the habitable zone

In this study we investigated the interiors of rocky exoplanets in order to identify those that may have large quantities of water. We modelled the interiors of 28 rocky exoplanets, assuming four different layers – an iron core, a rock mantle, a high-pressure ice layer, and a surface ice/water layer. Due to observational bias, our study is limited to habitable zone exoplanets. We determined a range of possible water mass fractions for each planet consistent with the modelled planetary structures. We calculated the tidal heating experienced by these exoplanets through gravitational interactions with their host stars, assuming a temperature- and composition-dependent Maxwell viscoelastic rheology. Assuming radioactive elemental abundances observed in Solar System meteorites, we also calculated the radiogenic heat flux inside the planets. We estimated the probability of the presence of a thick ocean layer in these planets, taking into account the effect of both tidal and radiogenic heating. Our results showed that Proxima Centauri b, Ross 128 b, Teegarden’s b and c, GJ 1061 c and d, and TRAPPIST-1 e may have an extended liquid water reservoir. Furthermore, extremely high H2O-content of the exoplanets Kepler-62 f, Kepler-1652 b, Kepler-452 b, and Kepler-442 b suggests that these planets may maintain a water vapour atmosphere and may in fact be examples of larger ocean worlds. Upon the discovery of new rocky exoplanets beyond the habitable zone, our study can be extended to icy worlds.

EXPERIMENTAL STUDY OF CONDENSATION OF WATER ON POLYDIMETHYLSILOXANE-COATED COPPER SURFACES

Modification of surfaces to enable dropwise condensation (DWC) is a promising approach for achieving high condensation rates. In this work, we present an experimental study on condensation of water on copper surfaces coated with an ultrathin, 5-10 nm thick polydimethylsiloxane (PDMS) layer. This hydrophobic coating possesses a very low thermal resistance, which in combination with copper substrate enables achieving high condensation rates in heat transfer applications. The PDMS-coated copper substrates have been fabricated with a newly developed method, which involves turning, sanding, polishing, oxidation, and polymer coating steps. The measured static contact angle was 110° ± 1°, and the contact angle hysteresis was 2°. The achieved very low hysteresis is advantageous for promoting DWC. The surface showed no aging effects during 100 repetitions of advancing and receding contact angle (ARCA) measurements. Condensation heat transfer on uncoated and PDMS-coated copper surfaces surfaces has been studied experimentally in a saturated water vapor atmosphere at 60°C. An enhancement factor for heat flux and heat transfer coefficient of up to 1.6 was found on PDMS-coated copper surfaces compared to uncoated surfaces, which decreased to 1.1 on the second and third day of condensation operation. Images of the condensation surface were recorded while conducting condensation experiments and post processed to evaluate drop departure diameter and frequency of drop sweeping events. It has been shown that the behavior of the heat transfer coefficient correlates with the frequency of the sweeping events.

Ultraviolet photo-response properties of bush-like ZnO nanorods deposited by chemical bath deposition

“Bush-like zinc oxide nanorods (ZnO NRs) has been deposited on soda-lime glass substrate via two step deposition process: seed layer deposition through Atmospheric chemical vapor deposition (APCVD) followed by chemical bath deposition (CBD) for growing NRs. Depositional parameters were carefully optimized so as to obtain a porous bush-like aggregation of ZnO NRs. X-ray Diffraction confirmed the formation of ZnO and scanning electron microscope showed bush-like aggregation of ZnO NRs. Transmission Electron Microscopy revealed that mostly non-polar {101¯0} and {112¯0} surfaces were exposed to the ambience. Room temperature Photoluminescence spectroscopy indicated the presence of mostly oxygen vacancy (VO) related defect states centered at 2.32 and 2.0 eV. Ultraviolet (UV) photo-response of the specimen was measured in air and nitrogen ambience. Higher photosensitivity (3166 % in nitrogen; 2233 % in air) but slower photo-response were observed under nitrogen ambience. It was found that UV photo-response properties of ZnO NRs were mostly a surface phenomenon dominated by adsorption-desorption mechanism of ambient oxygen molecules on the ZnO surface, mediated by surface defects related to VO, such as singly ionized state of VO. Bush-like aggregation of the ZnO NRs might have aided adsorption-desorption mechanism.”

(Invited) The Internal Oxidation Mechanism of Ti60 Alloy in NaCl-coated Environment at 600o C

When serving in the marine environment, the blades of aircraft engines will suffer serious high-temperature corrosion and their service life will be shortened. This is because the water vapour and salt particles (mainly NaCl) in the marine atmosphere will inevitably be involved in the engine, resulting in severe corrosion of materials. Previous studies on the degradation of titanium alloy under NaCl mainly focused on the active oxidation mechanism, while the mechanism of internal oxidation, which can significantly damage the mechanical properties of the titanium, is not clear. In addition, internal oxidation appears microstructure sensitivity, indicating that microstructure design may be an important way to improve high-temperature corrosion resistance in the marine environment.Consequently, for further understanding the internal oxidation mechanism and the influence of microstructure on corrosion, the composition and morphology of the internal oxidized layer of the Ti60 samples, which corroded with NaCl precoated at 600 oC in moist O2 flow for 100 h, have been studied.According to the results, Ti2O formed within the internal oxidized layer. With the thermodynamic calculation results, this observation proves that internal oxides do not result from the oxidation of metal chlorides. As it is known that titanium has a high affinity to oxygen, the internal matrix turns into titanium oxides with different valence states directly, while TiCl4(g) formed from active oxidation further transports outward and is oxidized at the position with high P(O2).The α secondary phase, located inside the β phase, is more sensitive to NaCl-induced corrosion than the α lamellar outside the β phase. This is because β phase and phase boundaries provide more high-energy channels for corrosive media transport to the α secondary phase, which results in severe loss of metallic elements and oxidation. The design of the α secondary phase may be one essential point for developing titanium alloys with a good combination of mechanical properties and corrosion resistance in marine environments. Figure 1

Sensitivity of summer precipitation simulation to the physical parameterizations in WRF over the Tibetan Plateau: A case study of 2018

The Tibetan Plateau (TP) holds a pivotal position in regional and global climate, whereas the atmospheric characteristics vary greatly in the simulation with different physical parameterization schemes at the gray-zone scale (around 9 km). In this study, 24 sets of experiments were set up with different cumulus parameterization schemes (CPSs), microphysics parameterization schemes (MPSs) and planetary boundary layer parameterization schemes (PBLSs) using the WRF model driven by the ERA5 reanalysis to explore the sensitivity and try to summarize a combination of parameterization schemes suitable for the simulation over TP. Based on comparisons against in-situ observations, most CPS experiments showed large wet bias and overestimated occurrence of precipitation events, and CTL without CPS and CU6 with Tiedtke CPS show better performance at gray-zone scale. The influence of MPS and PBLS is less than CPS on the simulation, and Thompson MPS and UW PBLS showed a better performance. Most of the CPS experiments reach an earlier and more intensive peak compared to the Integrated Multi-satellite Retrievals for GPM (IMERG) version 6 satellite precipitation product, except CTL, CU11, and CU6, which show closer but weaker peaks. CPS experiments simulate more precipitation associated with water vapor transporting into TP and anomalous cyclonic circulation against CTL. The less water vapor transport from the south edge of TP in the CTL against CU14, CU16, and CU2, leads to more local precipitation. Graupel particles and the warm-rain process play a crucial role in the precipitation simulation with different MPSs. Although with less water vapor in the low atmosphere, MP2 simulates more precipitation due to more graupel particles and warm-rain processes against CTL. PBLSs have a substantial impact on latent heat, then influence evaporation and precipitation. The lower PBL height usually leads to more latent heat and more precipitation.

Is interannual grain yield decline of intermediate wheatgrass influenced by management and climate in the Upper Midwest?

Perennial crops have the potential to provide sustainable food production while promoting multiple ecosystem services. Intermediate wheatgrass (IWG) is a perennial grass that is currently being domesticated as a perennial grain crop. However, one major hurdle limiting producer adoption is its interannual grain yield decline. While such a phenomenon has an evolutionary basis and has been reported in other perennial grain crops, there are currently conflicting reports about the extent of this phenomenon in IWG. To address this challenge, we have assembled a unique dataset integrating 13 field experiments conducted by the same research team in Minnesota, USA where IWG yield trials were established over 3–4 years, covering 24 location-years representing 9 treatments and up to 3424 plot-level yield observations. Our goals were to 1) determine the extent and magnitude of IWG yield decline and 2) examine the relative contribution of crop management and climate in mitigating IWG yield decline if it exists. Our results indicate that IWG grain yield decline starts during the second production year in Minnesota and continues annually at an average rate of 200–225 kg ha−1 yr−1, driven by a reduction in harvest index which declined at a rate of 2% yr−1. This decline occurred regardless of crop management practices, but some approaches, particularly optimal nitrogen application, plant density and cultivar choice increased grain yield potential. IWG productivity was also influenced by environmental gradients, with the strongest effect attributable to rising atmospheric drought or vapor pressure deficit (VPD), which influenced yield decline locally. Overall, the analysis indicated that optimal management, in concert with breeding towards more productive and climate-resilient varieties have the potential to reduce IWG decline in Minnesota.

An adaptive cabin air recirculation strategy for an electric truck using a coupled CFD-thermoregulation approach

Cabin climatization is one of the largest auxiliary loads in an electric vehicle, and its performance significantly affects the driving range. Recirculating climatized air from the cabin has been shown to reduce energy consumption, but at the risk of fogging the windows and deteriorating the air quality. Therefore, many automobile manufacturers refrain from adopting it at low ambient temperatures. In this paper, an adaptive recirculation strategy that takes these issues into account is proposed and studied on an electric truck cabin while heating. Numerical simulations were performed using a coupled CFD-thermoregulation model, with the consideration of humidity and CO2. The JOS-3 thermoregulation model was employed for estimations of skin temperatures and evaporation of vapor from the skin, and the Berkeley comfort model was used to evaluate the comfort metrics. Ten scenarios were considered at various vehicle speeds, temperatures, and relative humidity levels while evaluating them with and without the proposed return-air strategy. The controller adapted between humidity and CO2-critical conditions during run-time. The fresh-air mass flow requirements reduced with increasing difference between the setpoint and ambient vapor mass fractions under humidity critical conditions, and plateaued at 10 g/s where CO2 was more critical. The proposed strategy provided energy savings ranging from 9% to 34% depending on the operating condition.

Evaluation of the Influence of 2008 Scoping Plan to Carbon Emissions in California by DID

Global warming has been a crucial issue these years as the development of human society and technologies. The main factor is the greenhouse gas emissions, including water vapor, methane, carbon dioxide and nitrous oxide in the earth atmosphere. There are many countries with different kinds of policies to reduce greenhouse gas emissions to slow down the speed of global warming and protect the world environment, such as the California 2008 Scoping Plan. Difference-in-Difference is an estimation method to evaluate the effectiveness of a policy change on a group of individuals. This study selects the transportation sector as the indicator of carbon emissions in California and uses the data from 2004 to 2014 in all 51 states in the U.S. to estimate the influence of 2008 Scoping Plan on carbon emissions in California. The result shows the policy had a positive effect on reducing the carbon emissions in the transportation sector in California, which means that the Scoping Plan is worth continuing to implement and improve to achieve the goal of decreasing greenhouse gas emissions to protect the global environment.

Optoelectronic enhancement of photocurrent by cyanobacteria on sustainable AP-VPP-fabricated PEDOT electrodes

Photosynthetic microrganisms, including cyanobacteria, can be interfaced with electrodes in biophotovoltaic devices (BPVs) for solar energy conversion. Effective BPV electrodes need to be conductive, transparent, flexible, biocompatible and environmentally friendly, while also being cost-effective, abundant in material and lightweight. The utilisation of electrically conducting polymers (CPs), particularly poly(3,4-ethylenedioxythiophene) (PEDOT) fabricated by an atmospheric pressure vapor phase polymerisation (AP-VPP) technique, is a promising avenue for BPV applications. However, challenges remain in optimising their performance as CPs are dynamic optoelectronic materials, and their interaction with photosynthetic biocatalysts under a range of conditions has not been explored thoroughly. Here we show that AP-VPP PEDOT electrodes hold promise for interfacing with cyanobacteria in BPVs to generate green electricity under red and blue light and moderate applied potentials with exogenous electron mediators. The highest non-mediated photocurrent achieved was 0.48 µA cm−2, with a two-layer PEDOT electrode at 0.5 V applied potential and blue light. The highest mediated photocurrent achieved was 2.73 µA cm−2, with a one-layer PEDOT electrode at 0.3 V applied potential and blue light and the exogenous electron mediator 2,6-dichloro-1,4-benzoquinone (DCBQ). The proposed approach to fabricating PEDOT electrodes offers a new pathway for developing sustainable electrodes for BPVs and pinpoints strategies for future optimisation for achieving high-performance outcomes.