Fraction Of Surface Research Articles

Effects of ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol on tin electrodeposition

Electrodeposition of Tin (Sn) is studied in the presence of ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol (ETT). Cyclic voltammetry (CV), chronoamperometry, and chronopotentiometry are conducted to characterize the electrochemical behavior of Sn with the addition of ETT. Several influencing factors such as the ETT concentration, rotation rate, and potential scan rate are systematically investigated, and it is found that ETT suppresses Sn deposition at a certain negative potential range due to a potential dependent adsorption of ETT. This adsorption of ETT is further dependent not only on the empty surface fraction but also the occupied fraction or surface coverage. Moreover, various additives containing different functional groups of ETT are used to determine the key structural component for the inhibition effect.

Investigations in the tape-to-tape contact resistance and contact composition in superconducting CORC® wires

Conductor on Round Core (CORC®) wires and cables, constructed from multiple layers of helically wound REBa2Cu3O7−δ tapes, are a promising cable technology for high field magnet applications. An important feature of high-temperature superconductor cables is the ability to share current between conductors, allowing current to bypass drops in I c and minimizing the risk of hot spot formation, which could lead to potential burnout in the superconductor. In contrast to stacked-tape cables, which have continuous contact between tapes, in CORC® the transfer points occur at discrete tape crossovers. The tape-to-tape contact resistance, R c, plays a critical role in the current sharing capabilities and current distribution in cables. For the work reported here, special CORC® wires were manufactured using different winding parameters to investigate variations in R c. Variations comprised inclusion of a lubricant, different lubricant conductivity, inclusion of pre-tinning, and heating briefly to melt the solder. Cables were first tested as straight lengths, followed by bending to a 10 cm diameter. In straight cables R c values ranged from 1 to over 1000 μΩ cm2, depending on cabling parameters, with the highest values being found for cables made by the present ‘standard’ process. Bending the cables to a 10 cm diameter decreased R c by a factor 2–5. Tinning with PbSn decreased R c by three orders of magnitude compared to standard CORC® wires, and heat treating wires with tinned conductor resulted in only a small further decrease in R c. Based on the measured R c at an electric field of 1 μV cm−1 the resulting current transfer length between layers can range from a few millimeters to a tens of centimeters. Examination of contacts with a laser confocal microscope showed plastic deformation of the copper at the edges of the contact overlap area, apparently caused by thicker plating at tape edges digging into the copper of neighboring layers. These images reveal that only a fraction of the total contact surface may actually be touching when there is nothing to compensate for height differential. Images of the PbSn coated tapes indicated that application of solder produces a much more uniform contact surface and higher contact area. Furthermore, imaging of CORC® cross-sections confirmed that in the non-tinned cables there are many regions where tapes are not in contact, while in contrast the PbSn cable shows significantly more contact between the tapes. These different imaging techniques reveal that tape surface morphology is a significant parameter in determining R c.

Effect of humic acid on lysozyme interaction with montmorillonite and kaolinite

Humic acid (HA) as a soil natural organic matter (NOM) can participate in the interaction between proteins and clay minerals, depending on clay type, HA and protein content, and solution conditions. The effect of HA on the interaction of lysozyme (LSZ) with kaolinite (Kao) and montmorillonite (Mont) was investigated at (initial) pHi 5 and 8. In the solutions containing both HA and LSZ, HA/LSZ complexes were formed with a net charge density depending on pH and HA/LSZ mass ratio f. LSZ adsorption on clays in the presence of HA is dominated by adsorption of HA/LSZ complexes. The HA/LSZ mass ratio (fIEP,pHi) at the isoelectric point (IEP) is pH dependent. At f <fIEP,pHi the HA/LSZ complexes are positively charged and adsorb well to the negatively charged Mont and Kao surface fractions. The adsorption levels on Mont are considerably larger than on Kao, which is mainly due to the much larger area fraction of modestly hydrophobic basal plates of Mont. The presence of HA increased the plateau adsorption of LSZ on Kao and Mont for both pHi values, and the LSZ adsorption increased with increasing HA content and pHi values due to a decreasing mutual repulsion of the bound HA/LSZ complexes. At pHi 8 complications arose for low initial LSZ concentrations, for f <fIEP,pHi the HA/LSZ complexes were only weakly positive and formed dispersed aggregates and for f >fIEP,pHi the HA/LSZ complexes were negative, both conditions caused relatively high equilibrium concentrations of LSZ in solution that decreased with increasing initial LSZ concentration. The present results enhance our insight in protein soil interactions for the case that clay particles are brought in contact with aqueous solutions that contain modest amounts of both NOM and protein and stress the importance of the NOM/protein mass ratio and solution pH.

Salt-Sensitive Hypertension Induces Osteoclastogenesis and Bone Resorption via Upregulation of Angiotensin II Type 1 Receptor Expression in Osteoblasts.

Hypertension is a chronic-low grade inflammatory disease, which is known to be associated with increased bone loss. Excessive activity of the local renin–angiotensin system (RAS) in bone leads to increased bone resorption. As inflammatory cytokines may activate RAS components, we hypothesized that the elevated proinflammatory cytokine levels in hypertension activate bone RAS and thus lead to increased bone resorption. To investigate whether salt-sensitive hypertension (SSHTN) induces osteoclastogenesis and bone resorption, we generated a model of SSHTN in C57BL/6J mice by post-N ω-nitro-l-arginine methyl ester hydrochloride (l-NAME) high-salt challenge. SSHTN led to the reduction of distal femur trabecular number and bone volume fraction, while trabecular separation of femoral bone showed a significant increase, with no change in cortical thickness. Histomorphometric examination showed a significant reduction in trabecular bone volume fraction with an increased number of multinucleated tartrate-resistant acid phosphatase (TRAP)-positive cells and increased osteoclast surface fraction in the trabecular distal femur of hypertensive mice. Furthermore, analysis of gene expression in bone tissue revealed that TRAP and RANKL/OPG mRNA were highly expressed in hypertensive mice. TNF-α and angiotensin II type 1 receptor (AGTR1) mRNA and protein expression were also upregulated in SSHTN mice. These observations suggested that TNF-α may have an effect on AGTR1 expression leading to osteoclast activation. However, TNF-α stimulation did not promote AGTR1 mRNA expression in osteoclast precursors in culture, while TNF-α increased AGTR1 mRNA expression in osteoblast culture by activation of downstream p38. Angiotensin II was also shown to increase TNF-α-induced RANKL/OPG mRNA expression in primary osteoblast culture and osteoclastogenesis in a TNF-α-primed osteoblast and osteoclast precursor co-culture system. In addition, local injection of lipopolysaccharide into the supracalvariae of SSHTN mice markedly promoted osteoclast and bone resorption. In conclusion, mice with SSHTN show increased osteoclastogenesis and bone resorption due mainly to increased TNF-α and partly to the upregulation of AGTR1 in osteoblasts.

Occurrence and Discrepancy of Surface and Column Mole Fractions of CO2 and CH4 at a Desert Site in Dunhuang, Western China

Carbon dioxide (CO2) and methane (CH4) are the two major radiative forcing factors of greenhouse gases. In this study, surface and column mole fractions of CO2 and CH4 were first measured at a desert site in Dunhuang, west China. The average column mole fractions of CO2 (XCO2) and CH4 (XCH4) were 413.00 ± 1.09 ppm and 1876 ± 6 ppb, respectively, which were 0.90 ppm and 72 ppb lower than their surface values. Diurnal XCO2 showed a sinusoidal mode, while XCH4 appeared as a unimodal distribution. Ground observed XCO2 and XCH4 were compared with international satellites, such as GOSAT, GOSAT-2, OCO-2, OCO-3, and Sentinel-5P. The differences between satellites and EM27/SUN observations were 0.26% for XCO2 and −0.38% for XCH4, suggesting a good consistency between different satellites and ground observations in desert regions in China. Hourly XCO2 was close to surface CO2 mole fractions, but XCH4 appeared to have a large gap with CH4, probably because of the additional chemical removals of CH4 in the upper atmosphere. It is necessary to carry out a long-term observation of column mole fractions of greenhouse gases in the future to obtain their temporal distributions as well as the differences between satellites and ground observations.

Estimation of the “whitecap” lifetime of breaking wave

The paper presents the results of a study of the lifetime of wind-wave breaking (“whitecaps”) and the spatial distribution of the moments of wave-breaking initiation along the profile of a long surface wave. The results obtained during the specialized experiments from an oceanographic platform in the Black Sea are given. The registration of the whitecaps was carried out based on the video recordings of the sea surface. The surface waves’ characteristics were measured and the meteorological information was recorded simultaneously with the video recordings. It is shown that the distribution of the whitecaps’ lifetime is well described by an exponential law. It was found that the ratio of the lifetime of an individual whitecap to the period of the breaking wave is 0.3. The distributions of the above-mentioned ratio are similar for different wind and wave conditions. It is indicated that the generation of whitecaps occurs mainly in the region of the crest of a long wave with a shift to its front slope on average by 9.6 of the phase of the long wave. The whitecap having arisen at the leading edge shifts to the trailing edge of the long wave during its lifetime, so that the phase difference between the breaking initiation and the maximum of the surface fraction covered by the whitecaps equals 21.6.

Reconciling historical changes in the hydrological cycle over land

The sixth Intergovernmental Panel on Climate Change (IPCC) assessment report confirms that global warming drives widespread changes in the global terrestrial hydrological cycle, and that changes are regionally diverse. However, reported trends and changes in the hydrological cycle suffer from significant inconsistencies. This is associated with the lack of a rigorous observationally-based assessment of simultaneous trends in the different components of the hydrological cycle. Here, we reconcile these different estimates of historical changes by simultaneously analysing trends in all the major components of the hydrological cycle, coupled with vegetation greenness for the period 1980–2012. We use observationally constrained, conserving estimates of the closure of the hydrological cycle, combined with a data assimilation approach and observationally-driven uncertainty estimates. We find robust changes in the hydrological cycle across more than 50% of the land area, with evapotranspiration (ET) changing the most and precipitation (P) the least. We find many instances of unambiguous trends in ET and runoff (Q) without robust trends in P, a result broadly consistent with a “wet gets wetter, but dry does not get drier”. These findings provide important opportunities for water resources management and climate risk assessment over a significant fraction of the land surface where hydrological trends have previously been uncertain.

Dust mass loss during the recent outburst of comet C/2014 UN271 Bernardinelli–Bernstein

ABSTRACT The paper presents the results of numerical simulations of the mass ejected during the outburst of comet C/2014 UN271 Bernardinelli–Bernstein in large heliocentric distances. Determining the value of the mass ejected is one of the key factors determining the amplitude of the cometary outburst. It was assumed in the considerations that the scattering of the incident sunlight takes place on dust aggregates and dust agglomerates. In both of these cases, the key parameter in the context of determining the value of the mass ejected is the fraction of the nucleus surface that was active during quiet sublimation and the outburst. It was determined that the value of the mass ejected that caused the outburst fluctuated in the range from 107 to 108 kg. Moreover, the outburst itself, by exposing a fragment of the nucleus, rejuvenates the surface, at least on the local scale. The calculations performed refer to the outburst of comet C/2014 UN271 Bernardinelli–Bernstein on September 9, 2021.

In situ generated proppants for shale reservoirs

A large fraction of the fractured surface created during hudraulic fracturing is not propped. Injected proppants often settle near-wellbore in low viscosity fracturing fluids like slick water and do not reach the end of fractures. Many microfractures are too narrow to accommodate injected proppants and close during production. Poor placement of proppant leads to a loss of fracture conductivity and undermines the productivity of shale wells. In this study, reactive chemicals are injected to generate hydroxyapatite crystals on calcite-rich shale surfaces to act as in-situ proppants to improve microfracture conductivity. Batch experiments were conducted with reservoir shale samples in both low salinity frac water and high salinity brine. Crystals were generated in both low and high salinity brines. The crystals grew to several hundred microns and tended to form on calcite-rich shale surfaces. The hardness data showed that properly designed formulations could avoid the shale softening and even increase the hardness of the fracture surface (from 230 to 280 MPa). Reactive flow experiments were performed to evaluate fracture conductivity change after the chemical treatment. Micro-CT and scanning electron microscopy were used to visualize in situ proppants. A 3–10 times increase in post fracture conductivity was observed for both reservoir and outcrop shale samples. The propping of the microfractures can decrease the production decline during hydrocarbon production in shale reservoirs.

Tropical extreme droughts drive long-term increase in atmospheric CO2 growth rate variability

The terrestrial carbon sink slows the accumulation of carbon dioxide (CO2) in the atmosphere by absorbing roughly 30% of anthropogenic CO2 emissions, but varies greatly from year to year. The resulting variations in the atmospheric CO2 growth rate (CGR) have been related to tropical temperature and water availability. The apparent sensitivity of CGR to tropical temperature ({{{{{{rm{gamma }}}}}}}_{{{{{{rm{CGR}}}}}}}^{{{{{{rm{T}}}}}}}) has changed markedly over the past six decades, however, the drivers of the observation to date remains unidentified. Here, we use atmospheric observations, multiple global vegetation models and machine learning products to analyze the cause of the sensitivity change. We found that a threefold increase in {{{{{{rm{gamma }}}}}}}_{{{{{{rm{CGR}}}}}}}^{{{{{{rm{T}}}}}}} emerged due to the long-term changes in the magnitude of CGR variability (i.e., indicated by one standard deviation of CGR; STDCGR), which increased 34.7% from 1960-1979 to 1985-2004 and subsequently decreased 14.4% in 1997-2016. We found a close relationship (r2 = 0.75, p < 0.01) between STDCGR and the tropical vegetated area (23°S – 23°N) affected by extreme droughts, which influenced 6-9% of the tropical vegetated surface. A 1% increase in the tropical area affected by extreme droughts led to about 0.14 Pg C yr−1 increase in STDCGR. The historical changes in STDCGR were dominated by extreme drought-affected areas in tropical Africa and Asia, and semi-arid ecosystems. The outsized influence of extreme droughts over a small fraction of vegetated surface amplified the interannual variability in CGR and explained the observed long-term dynamics of {{{{{{rm{gamma }}}}}}}_{{{{{{rm{CGR}}}}}}}^{{{{{{rm{T}}}}}}}.

Morphology and distribution of cemented product formed via cementation over Zn in zinc sulfate solution relevant to roast-leach-electrowin process

The morphology and composition of cemented products formed by Cu cementation in a ZnSO4 solution containing Cu2+ using Zn as the cementation agent were investigated. The influence of several factors on the characteristics of the cemented products, such as the temperature and pH of solution, ultrasound field, and suspended SiO2 particles, was studied separately. The cemented products were characterized using optical microscopy, scanning electron microscopy with energy dispersive X-ray, and X-ray diffraction. The Cu2+ content in the solution after the cementation process was determined using inductively coupled plasma-atomic emission spectroscopy. The results show that the cemented products can be effectively removed from the Zn surface when the rotating Zn sample is immersed in the solution containing suspended SiO2 particles, enhancing the Cu cementation and increasing the utilization efficiency of Zn especially for its addition near the stoichiometric amount. The high-power ultrasound can form a cemented product layer with large cracks favoring a solution permeation through the product layer; additionally the formation of basic Zn salts is enhanced, which are detrimental to Cu cementation. The pH of the solution greatly impacts on the morphology and composition of the cemented product on the Zn surface in the pH range of 0.5–4.5; a low pH of 0.5 or 1 can expose a large fraction of the Zn surface without the cemented product coverage. The enhanced Cu cementation at a higher temperature was confirmed by more cemented product obtained after 4-h cementation at 60 °C than those at lower temperatures.

Seasonally disparate responses of surface thermal environment to 2D/3D urban morphology

The driving mechanisms of urban surface thermal environments usually differ with season. However, to date, the seasonal differences in the impacts of two-dimensional (2D) and three-dimensional (3D) building and tree morphologies on land surface temperature (LST) remain poorly understood. Additionally, there has yet to be a quantitative attempt to separate the direct effects of building and tree morphologies on LST from the indirect effects from 3D perspectives. Here, using Nanjing, China as an example, we investigated the seasonally disparate responses of LST to the 2D and 3D building and tree morphologies, by combining boosted regression trees and a structural equation model (SEM). Our findings show that the predominant factor that affects the spatial pattern of LST is the percent cover of buildings (PER_Build) in spring and summer, while the sky view factor (SVF) dominates LST variations in autumn and winter. The LST responsiveness to changes in these factors also showed a large seasonal variation. In summer, LST increased with PER_Build, and the greatest warming effect occurred when the building surface and tree canopy fractions were lower than 25% and 40%, respectively. In winter, by comparison, the variations in SVF and PER_Tree led to a larger change in LST. Further results using the SEM model suggest that LST variation is governed by more 2D building structures in spring and summer, whereas 3D building structures have a more dominant impact on LST in autumn and winter. Most of the overall impacts resulting from the 3D building and horizontal tree structures are direct throughout each season. However, the overall impacts of the 2D building structure on LST are mainly direct in spring and summer yet indirect in autumn and winter. In all seasons, the indirect impacts of 2D and 3D building structures on LST primarily originate from the horizontal and vertical tree structures, respectively. We consider that these findings can guide designing optimization strategies for urban heat mitigation for different seasons from 2D and 3D perspectives.

Effect of Grinding and Regenerative Heat Treatment on the Fracture Resistance of a Zirconia/Porcelain Veneer Interface.

To experimentally assess the effect of regenerative heat treatment (HT) on yttria-stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP) to guarantee veneer adhesion strength. One surface of bar-shaped Y-TZP specimens was ground (G) with a diamond stone, while the control samples (C) were not. Groups C900 and G900 were submitted to HT at 900°C for 60 min, whereas groups C1000 and G1000 were submitted to HT at 1000°C for 30 min. The treated surfaces were characterized by x-ray diffractometry (XRD), scanning electron microscopy (SEM), and optical and mechanical profilometry. The energy release rate through interface fracture was determined by a four-point bending test on notched Y-TZP veneered specimens. XRD was refined by the Rietveld method, mean roughness (Ra) and energy release rate were submitted to two-way ANOVA (a = 0.05), and the images were analyzed descriptively. The monoclinic phase (vol%), means of Ra (µm), and the energy release rate (J/m2) were, respectively: C = 1.2/0.17/6.8, C900 = 0.0/0.18/6.6, C1000 = 0.0/0.18/7.6, G = 2.6/1.16/8.3, G900 = 0.0/1.07/8.0, and G1000 = 0.0/1.01/5.7. The surface fraction of monoclinic zirconia increased by grinding and decreased by HT. Ra also increased after grinding (p < 0.005) but remained unaltered after HT (p = 0.22). Increased irregularity was observed in the G groups and a subtle smoothing of the surface after HT. After the fracture of the bilayers, a residual amount of porcelain could be seen on the zirconia surface in all groups. The energy release rate was statistically equal among all groups (p > 0.05). Heat treatment after grinding completely restored the tetragonal phase of zirconia without altering the energy release rate during interfacial fracture.

MARMIT-2: An improved version of the MARMIT model to predict soil reflectance as a function of surface water content in the solar domain

This paper presents MARMIT-2, a radiative transfer model that predicts the spectral reflectance of soils in the solar domain (0.4–2.5 μm) as a function of their surface moisture. This is an improved version of MARMIT (multilayer radiative transfer model of soil reflectance) that represents a wet soil as a dry soil topped with a thin layer of liquid water. The changes brought in this article concern the mixing of the spectral reflectance of the dry and wet soil areas, the transmission of diffuse light in the water layer, and the inclusion of soil particles in the water layer. Wet soil reflectance is now expressed in terms of dry soil reflectance and three free parameters: the thickness of the water layer, the surface fraction of the wet soil, and a new parameter, the volume fraction of soil particles in the water layer. With more accurate physical modeling, MARMIT-2 simulates soil spectral reflectance with better accuracy than MARMIT. In particular, the fit of the soil reflectance spectra is much better for high water contents, both in the visible range (0.4–0.7 μm) and in the water absorption bands around 1.45 μm and 1.95 μm. The average root mean square error between measured and predicted reflectance obtained on a set of 225 soil samples is about 0.8% with MARMIT-2 versus 1.8% with MARMIT.

A Scale-Separating Framework for Fusing Satellite Land Surface Temperature Products

The trade-off between spatial and temporal resolutions of satellite imagery is a long-standing problem in satellite remote sensing applications. The lack of daily land surface temperature (LST) data with fine spatial resolution has hampered the understanding of surface climatic phenomena, such as the urban heat island (UHI). Here, we developed a fusion framework, characterized by a scale-separating process, to generate LST data with high spatiotemporal resolution. The scale-separating framework breaks the fusion task into three steps to address errors at multiple spatial scales, with a specific focus on intra-scene variations of LST. The framework was experimented with MODIS and Landsat LST data. It first removed inter-sensor biases, which depend on season and on land use type (urban versus rural), and then produced a Landsat-like sharpened LST map for days when MOIDS observations are available. The sharpened images achieved a high accuracy, with a RMSE of 0.91 K for a challenging heterogeneous landscape (urban area). A comparison between the sharpened LST and the air temperature measured with bicycle-mounted mobile sensors revealed the roles of impervious surface fraction and wind speed in controlling the surface-to-air temperature gradient in an urban landscape.

Association analysis on spatiotemporal characteristics of block-scale urban thermal environments based on a field mobile survey in Guangzhou, China

City blocks typically exhibit diverse thermal environmental characteristics due to their self-character complex spatial morphology and lateral thermal interactions from neighboring blocks. A field survey illustrating the spatiotemporal characteristics of block-scale thermal environments is urgently required to explore the inner-associated effects. A mobile survey method was conducted with two selected typical case regions during summer in Guangzhou, China. A block-based local climate zone (LCZ) mapping method was applied to the case regions, and diversified LCZ types that coexist in irregular states were obtained. Then, a multi-step data processing method integrating temporal correction and GIS-based spatial analysis was implemented to obtain the spatiotemporal distribution atlas of air temperature in LCZ blocks. Throughout this study, the air temperatures displayed time-varying characteristics and changed significantly with LCZ types. The correlation analysis showed that the sky view factor and pervious surface fraction present significant positive effects on block-scale air temperature during the daytime. Next, a spatial heterogeneity analysis conducted by fitted semivariogram curves at different times revealed the spatial variability of the urban thermal environment. Additionally, further spatial autocorrelation analysis of thermal interactions between blocks resulted in significant spatial cluster characteristics of air temperatures in the case regions.

Aluminum doping of mesoporous silica as a promising strategy for increasing the energy storage of shape stabilized phase change materials containing molten NaNO3: KNO3 eutectic mixture

Efficient thermal energy storage at high temperature is necessary for both industrial waste heat utilization and continuous solar power generation. Shape-stabilized phase change materials containing mesoporous aluminosilicates and eutectic NaNO3: KNO3 (1:1 mol) molten salt mixture were obtained at 90% wt. salt. The influence of aluminum doping was studied for the first time. All samples show thermal stability up to 550 °C and two distinct phase transitions corresponding to the melting/freezing of nanoconfined and interparticle salt phases. The radius and spherical shape of the nanoconfined phase were determined from the melting and freezing point depressions with respect to bulk. The enthalpy decrease was quantified in terms of surface tension and the contributions of a non-melting fraction of surface adsorbed ions. SBA-15 type aluminosilicates matrices yield composites with high latent heat storage of 76–77 Jg−1, of which 8 Jg−1 for the nanoconfined phase and good thermal reliability. Aluminum doping is a simple and promising strategy for obtaining high temperature, efficient thermal energy storage materials due to a lack of non-melting salt fraction. The resulting shape-stabilized PCMs have a higher operating temperature range and latent heat storage, offering a 36% increase in total heat capacity over the pristine salt.

The effect of increasing surface cover vegetation on urban microclimate and energy demand for building heating and cooling

The study examines the potential effects of adding vegetation to an urban neighborhood in Tel Aviv on the microclimate, and subsequently on the potential for cooling by night ventilation and on energy consumption for heating and air conditioning. Computer simulation was employed to first generate modified weather files that account for urban effects of location, surface cover and density in different building configurations. These files were then used to assess the climatic cooling potential (CCP) by night ventilation and as inputs for detailed computer simulation of building energy performance. The microclimate model simulation indicates that elevated urban night-time temperatures will increase summer cooling loads relative to the reference rural site, but this penalty will be more than offset by reduced winter heating loads, resulting in a net decrease of between 2 and 7% in electricity use for heating and cooling (depending on building characteristics). The main impact of the urban heat island in this case is the reduction in the potential for cooling by night ventilation, which is almost completely absent in the summer months. Consequently, the urban climate of Tel Aviv may increase the prevalence of air conditioning use and will make buildings more vulnerable to potential loss of electric power in case of shortages or blackouts during episodes of extreme heat. Implementing a strategy of extensive planting, so that a green surface fraction of 0.5 is obtained, results in a mean annual temperature reduction of about 0.3 °C and an energy saving relative to the current condition of about 2–3%.

The resilience of soil erosion rates under historical land use change in agroecosystems of Southern Spain

Land use change (LUC) is identified as one of the main drivers of soil erosion in the Mediterranean. However, very little information exists regarding the relationship between land use and erosion over longer time periods and on regional scales. We quantified the LUC in Southern Spain between 1956 and 2018, examining its effect on soil erosion and assessing the mitigation role of the permanent grassland (PG). The land use influence on erosion is represented by the RUSLE's C-factor, which was modelled using the Monte Carlo Method (MCM) based on historical LUC. Moreover, future LUC scenarios by 2038 were developed by binary logistic model (scFS) and by a complete conversion of PG to cropland (scPC), permanent crop (scPP) and forest and natural (scFP). Historically, Southern Spain has experienced an impressive intensification of its agricultural system. While soil loss variation is noted within the classes, no big variation is observed in cumulative erosion on a regional scale. The underlying reasons for this resilience are multifold, but mainly attributed to the fact that a small fraction of the total surface (20%), dominates total erosion (67%). The C-factor decrease in this area displays a LUC towards forest and natural area, suggesting an agriculture abandonment. On the other hand, the agricultural intensification that has taken place in the remainder of the area, contributes much less to overall soil erosion. Future LUC scenarios illustrate the importance of PG for erosion mitigation. scFS scenario does not project major changes. However, scCP and scPP, show an abrupt increase in regional erosion by 13% and 14%, while scFP shows a negligible reduction of erosion close to 0%. This allows to quantify the erosion mitigation offered by maintaining the PG and should be taken into account for future agricultural policy.

Impact of Pore Structure on Two-Electron Oxygen Reduction Reaction in Nitrogen-Doped Carbon Materials: Rotating Ring-Disk Electrode vs. Flow Cell.

The impact of pore structure on the two-electron oxygen reduction reaction (ORR) in nitrogen-doped carbon materials is currently under debate, and previous studies are mainly limited to the rotating ring-disk electrode (RRDE) rather than the practical flow cell (FC) system. In this study, assisted by a group of reliable pore models, the impact of two pore structure parameters, that is, Brunauer-Emmett-Teller surface area (SBET ) and micropore surface fraction (fmicro ), on ORR activity and selectivity are investigated in both RRDE and FC. The ORR mass activity correlates positively to the SBET in the RRDE and FC because a higher SBET can host more active sites. The H2 O2 selectivity is independent of fmicro in the RRDE but correlates negatively to fmicro in the FC. The inconsistency results from different states of the electrode in the RRDE and the FC. These insights will guide the design of carbon materials for H2 O2 synthesis.