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• This study delves into the influence of digital transformation on labour investment efficiency. • Digital transformation considerably enhances labour investment efficiency. • Digital transformation mitigates both overinvestment and underinvestment issues. This study delves into the influence of digital transformation on labour investment efficiency and its varied effects across different business phases. Utilizing panel regression and the instrumental variable model, the research analyses data from China's A-share listed companies spanning 2011–2021. Findings reveal that digital transformation considerably enhances labour investment efficiency, mitigating both overinvestment and underinvestment issues. Heterogeneity analysis further indicates that digital transformation fine-tunes resource distribution, especially aiding businesses in their growth and maturity phases. Contrarily, firms in a declining phase show no discernible impact from digital transformation. [ABSTRACT FROM AUTHOR]

A new dry fermentation biogas-pool(DFBP) was explored for family using in the countryside of Leting, Hebei province, China. The results showed that the biogas can be produced in a short time, and the methane percentage was over 40% on the second day by co-digestion of cornstalk and garden leaves. This kind of biogas was already suitable for the ignition. The daily biogas production was nearby 1 m 3 with the methane percentage around 54% which can satisfy the needs of daily biogas using by family of three people. The biogas residue can be reused as fertilizer to return to field. The construction of DFBP can solve the problem of living garbage disposal and realize recycling utilization of the energy which is helpful to the environmental improvement in the countryside. [ABSTRACT FROM AUTHOR]

Three individual seed sludges, which domesticated by filter paper (SS1), food waste (SS2) and grease (SS3), respectively, were used for enhancing the methane production of waste activated sludge (WAS). Also CaO-ultrasonic pretreatment was performed on WAS to evaluate the effectiveness on improving efficient anaerobic digestion (AD). The results showed that WAS being acidated for 24 h after CaO-ultrasonic pretreatment was an effective method for increasing initial methane production rate. The daily concentration of volatile fatty acids (VFAs) during the AD course showed that the propionic was easier to be reduced after adding seed sludge. The optimum seed sludge for improving methane production and biodegradability of WAS was SS3, which led to an increase in the methane production of 68.92% and VS reduction of 69.20% higher than the control. This pretreatment combined with adding optimum seed sludge can greatly improve clean energy generation from WAS. [ABSTRACT FROM AUTHOR]

China has the largest antimony (Sb) reserves and Sb production and consumption levels in the world. The Sb emissions from PET products have caused great concern regarding human health and environmental risks with the widespread use of Sb-containing polyethylene terephthalate (PET) products in China. However, the main sources and magnitude of Sb risks in the PET life cycle for humans and the environment are unknown. Therefore, the PET cycle is constructed. And we further quantified the Sb flow and emissions in the PET life cycle and mass ranges of Sb entering the biosphere in each stage. The results show that in the PET life cycle, Sb emissions and risks are the highest in the manufacturing and use stage, especially in the fiber manufacturing and use stage, which is much higher than that of PET bottles, film, and engineering plastics. The Sb emissions and risks in the production stage are only next to that in the manufacturing and use stage, and a large amount of Sb directly enters the biosphere in this stage. It is worth noting that thousands of tons of Sb enter the biosphere in the reclamation and market trade stage. The study reveals the Sb emissions and risks during the PET life cycle and provides suggestions for Sb management in the PET life cycle to reduce the risks of Sb to humans and the environment. Image 1 • We analyzed the flow and environmental release of Sb from PET products in China. • In the life cycle of PET, Sb emission mainly comes from the M&U stages. • During the M&U stage, a total of 4.6–5.9 Gg of Sb entered the biosphere. • Sb leaching and exposure from PET products should be taken seriously. [ABSTRACT FROM AUTHOR]

Thermoelectric cooling suffers from low energy conversion efficiency (i.e., COP) which is a major bottleneck that hurdles its wide application, especially for large-scale systems. The COP of thermoelectric cooling system can be improved by integrating with other technologies. Due to its "free" nature, radiative sky cooling technology can potentially be integrated with thermoelectric cooling to obtain much higher system COP. This study introduces a novel radiative sky cooling-assisted thermoelectric cooling (RSC-TEC) system. The system has four different working modes under different operating conditions. A case study has been conducted for a two-story residential building that has 223 m2 living zone area located in Los Angeles, USA. Sensitivity analysis is first performed to size the system parameters. It is shown that the RSC-TEC system with a 0.83 m3 cold storage tank, 32 m2 radiative cooling surface area, and 101 thermoelectric modules (Laird ZT8-12), could achieve annual cooling COP of 1.87. Further analysis showed that daytime and nighttime cooling of the radiative sky cooling subsystem contribute to 55.0% and 45.0% of annual cold generation (heat dissipation) respectively, which indicates the critical importance of daytime cooling. The RSC-TEC system demonstrates a potential solution for large-scale adoption of the thermoelectric cooling technology. • A radiative sky cooling assisted thermoelectric cooling (RSC-TEC) system is proposed. • Sensitivity analysis is performed to size the system parameters. • Annual building energy simulation is conducted with EnergyPlus and MATLAB. • Annual cooling COP of 1.87 is achieved in a two-story residential building. • The RSC-TEC system demonstrates a potential solution for the wide adoption of thermoelectric cooling technology. [ABSTRACT FROM AUTHOR]

The piecewise quadratic polynomial collocation is used to approximate the nonlocal model, which generally leads to a nonsymmetric indefinite system (Chen et al. (2021) [5]). In this case, the discrete maximum principle is not satisfied, which might be trickier for the stability analysis of the high-order numerical schemes (D'Elia et al. (2020) [10] ; Leng et al. (2021) [26]). Here, we present a modified (shifted-symmetric) piecewise quadratic polynomial collocation for solving the linear nonlocal diffusion model, which leads to a symmetric positive definite system and satisfies the discrete maximum principle. Using Faulhaber's formula and Riemann zeta function, the perturbation error for symmetric positive definite system and nonsymmetric indefinite system are given. Then rigorous convergence analysis for the nonlocal models are provided under the general horizon parameter δ = O (h β) , with β ≥ 0. More concretely, the global error is O (h min ⁡ { 2 , 1 + β } ) if δ is not set as a grid point, while it recovers O (h max ⁡ { 2 , 4 − 2 β } ) when δ is set as a grid point. We also prove that the shifted-symmetric scheme is asymptotically compatible, which has the global error O (h min ⁡ { 2 , 2 β } ) as δ , h → 0. The numerical experiments (including two-dimensional case) are performed to verify the convergence. [ABSTRACT FROM AUTHOR]

• Novel design of a dynamic solar modulative smart window component. • Control of solar modulation performance of smart window components. • Correlation study between hydrogel film and IR-reflective coatings. • Monitoring space cooling annual saving with application of smart window component. Energy-efficient smart windows with dynamic modulation of solar heat gain in response to external stimulus such as ambient temperature variation have been of great interest. However, when a smart window technology is implemented over a commercial glazing system, its performance could be dramatically influenced by the pre-installed low-e coating. An implementable smart window component made of thermo-response hydrogel for dynamic solar modulation, either prefabricated with window structures for newly constructed building application or manufactured into a film for existing building retrofit, has been rationally designed in this work. An IR-reflective coating was integrated with the as-synthesized hydrogel film and the ultimate solar regulation performance has been evaluated. Compared to the bare hydrogel sample, the total light modulation ability from the hydrogel film with IR-reflective coating was tapered by 0.9–5.4% due to the blockage of a portion of IR radiation before transmitting through the hydrogel layer. This additional NIR blocking effect allows this window design preferably suitable for hot weather with high solar radiation. Annual energy simulations to a prototype commercial building have shown the thermo-responsive hydrogel window component prepared in this work yields annual space cooling energy savings of up to 8.1% for Tucson, AZ, USA, which gives a 30.6 kWh/yr·m2 cooling energy savings per square meter of window glass. [ABSTRACT FROM AUTHOR]

• Radiative sky cooling is integrated with attic ventilation to reduce attic temperature. • Daytime sub-ambient air cooling up to 5°C (with an air flow rate) is experimentally demonstrated under direct sunlight. • Attic temperature can be reduced by 15.5-21°C on typical summer day compared to shingle roof. • Substantial annual cooling energy saving can be achieved with different attic insulations at different locations compared to shingle roof. The building attic usually subjects to substantial solar heat gain and has much higher temperature compared to the conditioned living space during the day, especially in summer and in hot areas. Reducing attic temperature can reduce cooling energy consumption in buildings. However, conventional techniques such as cool roof or attic ventilation, suffer from either heating penalty in winter or limited attic temperature reduction. In this work, a new roof-integrated radiative air-cooling system is introduced, which couples radiative sky cooling with attic ventilation to reduce attic temperature. A radiative air cooler with 1.08 m2 surface area is constructed using a recently developed daytime radiative sky cooling metamaterial [Zhai et al., Science 355, pp. 1062–1066, 2017]. Experimental tests show that sub-ambient air cooling is achieved throughout 24-h day-and-night cycle in a summer day with clear sky conditions. Depending on air flow rates, measured sub-ambient temperature reductions of air are 5–8°C at night and 3–5°C at noon under direct sunlight, respectively. An in-house model is first developed for the radiative air-cooling system, the model is then coupled with EnergyPlus to study annual energy saving of buildings. The performance of the radiative air-cooling system is compared with three reference systems: shingle roof, attic ventilation, and cool roof. Results show that for a single-family house, attic temperature can be substantially reduced by 15.5–21.0°C, varying with attic insulation level, compared to shingle roof on typical summer days. Compared to a shingle roof (solar reflectance 0.25, thermal emittance 0.9) residential building with attic insulations of R-30 (RSI-5.28), R-10 (RSI-1.76), and R-0.8 (RSI-0.14), the roof-integrated radiative air-cooling system can achieve annual cooling energy savings of 0.4–1.5 kWh/m2 (4.6–18.8%), 1.2–3.6 kWh/m2 (10.2–41.4%), and 3.7–11.8 kWh/m2 (26.5–76.1%) respectively. [ABSTRACT FROM AUTHOR]

Radiative cooling technology dissipates heat to outer space through the atmospheric window. A radiative cooling membrane possessing spectrum-selective optical properties has been installed on the grain storage warehouses in Hangzhou, China for a field testing. The long-term measurement results show notable decreases in headspace temperature and grain temperature by as much as 9.8 °C and 4 °C, respectively. A building model is created with measurement data and extended to seven grain storage ecological zones to assess potential electricity savings and temperature reductions without air conditioning. For cases with air conditioners, a total electricity saving of 573 GWh/yr is expected if applied nationwide. Without air conditioners, the temperature could decrease by 5.1–9.9 °C and 3.8–6.9 °C for headspace and grain respectively when ambient temperature exceeds 25 °C, thus upgrading the grain storage levels in different grain storage ecological zones. The linear correlation between the cooling-degree-day values set at 18 °C and the electricity consumption was developed, and extended to a global map. It reveals that in areas with values less than 1000 °C d, radiative cooling technology can maintain quasi-low storage temperatures, eliminating the need for air conditioning. [Display omitted] [ABSTRACT FROM AUTHOR]

• Improved model developed to evaluate a metamaterial-based new cool roof performance. • The model incorporates the spectrum selective approach for radiative sky cooling. • Experiments of the metamaterial-based cool roof are conducted on reduced-size building. • The metamaterial-based cool roof can significantly reduce roof-induced cooling load. A new cool roof with potential to generate significant energy savings in buildings has been developed from a metamaterial film named as RadiCold. Considering that the RadiCold film has unique optical and thermal characteristics and the current Roof Thermal Transfer Value model neglecting the effect of roof thermal mass that may lead to overestimating the cooling load from roofs, this work developed an improved Roof Thermal Transfer Value model and validated the model for both RadiCold cool roof and traditional roofing structures. Data from the reduced-size model building experiments showed that the improved Roof Thermal Transfer Value model can accurately describe the heat gains or losses via the roofs. Under real-world weather conditions in the United States (Tucson AZ, Los Angeles, CA, and Orlando FL), the improved Roof Thermal Transfer Value model has been applied to three types of roof exterior finishing: shingle, Thermoplastic Polyolefin (a cool roof material) and RadiCold. In a typical meteorology year, the modeling results show that the shingle and Thermoplastic Polyolefin roof transfer 78.9–294.1 kWh/(m2·yr) and 8.5–128.2 kWh/(m2·yr) of heat into the building space, respectively, but the RadiCold cool roof dissipates 137.6–268.7 kWh/(m2·yr) of heat from the building space to outdoor environment (e.g., sky). The cooling load reduction from utilizing RadiCold cool roof results in cooling electricity savings of 113.0–143.9 kWh/(m2·yr) compared to the shingle roof and 88.0–92.4 kWh/(m2·yr) compared to the Thermoplastic Polyolefin roof for the three analyzed locations with an assumed air conditioning system's coefficient of performance of 3.0. [ABSTRACT FROM AUTHOR]

The importance of matrix micromechanics is increasingly recognized in cardiovascular research due to the intimate role they play in local vascular cell physiology. However, variations in micromechanics among arterial layers (i.e. intima, media, adventitia), as well as dependency on local matrix composition and/or structure, anatomical location or developmental stage remain largely unknown. This study determined layer-specific stiffness in elastic arteries, including the main pulmonary artery, ascending aorta, and carotid artery using atomic force indentation. To compare stiffness with age and frozen processing techniques, neonatal and adult pulmonary arteries were tested, while fresh (vibratomed) and frozen (cryotomed) tissues were tested from the adult aorta. Results revealed that the mean compressive modulus varied among the intima, sub-luminal media, inner-middle media, and adventitia layers in the range of 1–10 kPa for adult arteries. Adult samples, when compared to neonatal pulmonary arteries, exhibited increased stiffness in all layers except adventitia. Compared to freshly isolated samples, frozen preparation yielded small stiffness increases in each layer to varied degrees, thus inaccurately representing physiological stiffness. To interpret micromechanics measurements, composition and structure analyses of structural matrix proteins were conducted with histology and multiphoton imaging modalities including second harmonic generation and two-photon fluorescence. Composition analysis of matrix protein area density demonstrated that decrease in the elastin-to-collagen and/or glycosaminoglycan-to-collagen ratios corresponded to stiffness increases in identical layers among different types of arteries. However, composition analysis was insufficient to interpret stiffness variations between layers which had dissimilar microstructure. Detailed microstructure analyses may contribute to more complete understanding of arterial micromechanics. [ABSTRACT FROM AUTHOR]

Highlights • A kW-scale day-night radiative sky cooling system is demonstrated. • Daytime and nighttime cooling strategies based on optimum flow rates are investigated through modeling. • Daytime and nighttime cold water generation tests are conducted. • Predictive modeling of the system annual cooling performance is carried out. Abstract With the advancement in sub-ambient cooling of water during daytime under the sun with scalable-manufactured radiative cooling metamaterials, the challenge for applications lies in design and building of large-scale radiative cooling systems. Here, we present a kW-scale, 24-hour continuously operational, radiative sky cooling system, with both experimental study and detailed modeling. We first quantitatively show how water flow rate directly affects the system cooling power and inversely affects the water temperature drop. A day-and-night stagnant (flow rate = 0 L/(min·m2)) water cooling test of the system shows a consistent sub-ambient water temperature drop of 5–7 °C. A daytime cooling test of the system at a low flow rate of 0.227 L/(min·m2) yields a maximum sub-ambient temperature drop of 4.0 °C with an average net cooling power of around 80 W/m2. Further modelling for a typical metrological year (in Phoenix, Arizona) shows that the system could generate as much as 350 kWh cold (or 26 kWh/m2) with a sub-ambient temperature drop of 4–5 °C at a low flow rate of 0.1 L/(min·m2) during a typical summer month. The cold generated could be used to assist AC systems in regions or seasons with high ambient temperatures. [ABSTRACT FROM AUTHOR]

• A novel type of socket connection with specific shear keys was proposed. • Reliability of the proposed connection was verified through cyclic loading tests. • The configuration details of the connection were discussed. • The smallest embedment depth of the socket connection was explored. Socket connections have been widely used in accelerated bridge construction (ABC) for their construction convenience while the reliability of the connections under seismic load and the appropriate embedment depth become the main concerns of engineers and researchers. In this study, a novel type of socket connection with specific shear keys and inner and outer filled reinforced concrete was proposed for hollow concrete columns (HCCs). Cyclic loading tests of five specimens with the proposed socket connections were conducted to investigate their reliability. The results showed that all specimens failed in flexural failure of the HCC piers, identical with cast-in-place (CIP) connections, and had adequate ductility and energy dissipation capacity. The configuration details could be further simplified and the embedment depth could be 0.325 times the column diameters (0.325 D o) for the proposed socket connection according to the tests. The behavior model for the socket connections is also proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A nacre-inspired "rigid-and-soft" interphase was constructed between GO and epoxy. • The grafting layer number of GO was modulated to adjust the interphase. • The interphase showed synergistic effect in interfacial and mechanical properties. • Nanocomposites exhibited enhanced mechanical properties under extreme conditions. The interphase structure plays a significant role in the interfacial interactions and mechanical properties of epoxy-based nanocomposites. Inspired by the nacre's structure, a "rigid-and-soft" multilayer interphase was constructed between functionalized graphene oxide (GO) and epoxy matrix through grafting rigid polydopamine (PDA) and flexible polyetheramine D230 alternatively on GO surfaces. The structural and morphological characteristics of modified GO (MGO) with various numbers of grafted layers were characterized. The dispersion of MGO in epoxy matrix was investigated. The mechanical properties of nanocomposites at room temperature (RT) and liquid nitrogen temperature (LNT) were evaluated. MGO with three layers of PDA/D230 (MGO-L 3) endowed the nanocomposites with the highest mechanical properties, owing to the "rigid-and-soft" interphase which can synergistically enhance the stress transfer and accelerate the energy dissipation. At RT, nanocomposites showed the maximum increment of 25.8% in tensile strength and 13.0% in elongation at break compared to neat epoxy. At LNT, the corresponding increments could reach 6.8% and 23.1%, respectively. The influence of the "rigid-and-soft" interphase on the mechanical properties of MGO/epoxy nanocomposites under thermal cycling were investigated as well. Based on the fracture morphology, the toughening mechanisms of MGO at RT and LNT were both disclosed. [ABSTRACT FROM AUTHOR]

• Demonstration of how radiative cooling can reduce water consumption in thermal power plants. • Supplemental radiative cooling system reduces water consumption by 30–90%, without efficiency penalty. • Standalone radiative cooling system eliminates water consumption with 0–2.2% efficiency penalty. • Radiative cooling potential and water saving maps of the contiguous US. Evaporative wet cooling and dry cooling are gradually replacing water-intensive, thermally polluting once-through wet cooling in thermal power plants. Widespread adoption of evaporative wet cooling increases water losses to the atmosphere and still requires uninterrupted makeup water. Dry cooling substantially increases auxiliary power consumption and causes plant efficiency penalty. Therefore, efficient water-saving cooling technologies are of great importance. Here, we explore the water saving potential of day-night radiative sky cooling with and without evaporative wet cooling in thermal power plants. With a radiative cooling system size of 0.0055 km2/MW th normalized by the condenser thermal load at design, we show that a hybrid evaporative-radiative cooling system yields annual water savings of 30–60% in the dry and hot southwestern United States and 50–90% in other parts of the country without causing efficiency penalty. Furthermore, 100% water saving is achievable if the radiative cooling system functions as a stand-alone cooling system, with a much lower efficiency penalty and auxiliary power consumption than that of stand-alone dry cooling systems. [ABSTRACT FROM AUTHOR]

• An optically-switchable thermally-insulating VO 2 -aerogel hybrid film was proposed. • A coupled heat conduction and solar radiation heat transfer model was developed. • The U-value of the film is ~50% less than the value of single-pane windows. • The solar modulation ability of the film is ~20%. • This film can improve thermal comfort, avoid moisture condensation and overheating. Developing easy-to-install energy-efficient window retrofitting materials is important for reducing the heating and cooling loads of buildings. However, it is very challenging to achieve window retrofits that are simultaneously thermally insulating, visible-light transparent, and dynamically switchable in solar transmission. Here, a visibly transparent and thermally insulating film was proposed to reduce the energy loss through windows. By embedding insulator–metal phase transition vanadium dioxide (VO 2) nanoparticles inside an ultralow thermal conductivity aerogel film, the thermal insulation performance is greatly improved in such thermochromic film while the solar transmission can be dynamically switched in response to ambient conditions. A coupled heat conduction and solar radiation heat transfer model was developed to evaluate the effect of geometric features such as film thickness, nanoparticle size, and concentration on the thermal and optical performance of the proposed films. It was shown that a 3.0 mm thick film could achieve a low U-value of ~ 3.0 W/(m2K), and a high luminous transmittance of > 60% and a solar modulation ability of ~ 20%. This film improves the performance of single-pane windows by reducing the energy loss, improving thermal comfort, and avoiding moisture condensation in cold climates and overheating in hot climates. [ABSTRACT FROM AUTHOR]