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Super-gravity field was reported to strongly intensify the buoyancy-driven flow of liquid during solidification, affecting the solute convection and morphology of eutectic structure in binary alloys. In ternary eutectic alloys, certain two-phase regions with a coarse structure can usually be detected concurrently along with three-phase eutectics, leading to the formation of heterogeneous structure with limited ductility. Currently, Al–Ce–Ni ternary eutectic alloy was chosen as a modal system, which was reported for the first time to be solidified under super-gravity field with high volume fraction of three-phase eutectics. Meanwhile, the formation of ultrafine-fibrous interconnected Al11Ce3–Al3Ni eutectic clusters with more “chains” and higher spatial connectivity was detected mainly due to the relatively higher nucleation rate. The high volume fraction and refinement of interconnected Al11Ce3–Al3Ni eutectic clusters with excellent thermal stability could contribute to enhancement of ductility and tensile strength at elevated-temperature. Interestingly, the strength retention at 300 °C and 400 °C were able to reach up to ∼68.1 % and ∼33.2 %, respectively.

Source characteristics and health risks of indoor organophosphate esters (OPEs) are limited by the lack of knowledge on emission processes. This study attempted to integrate the contents and emissions of OPEs from indoor building materials to assess human health effects. Thirteen OPEs were investigated in 80 pieces of six categories of building materials. OPEs are ubiquitous in the building materials and ∑13OPE contents varied significantly (p< 0.05) from 72.8 ng/g (seam agent) to 109,900 ng/g (wallpaper). Emission characteristics of OPEs from the building materials were examined based on a microchamber method. Depending on the sample category, the observed initial area-specific emission rates of ∑13OPEs varied from 154 ng/m2/h (carpet) to 2760 ng/m2/h (wooden floorboard). Moreover, the emission rate model was developed to predict the release levels of individual OPEs, quantify source contributions, and assess associated exposure risks. Source apportionments of indoor OPEs exhibited heterogeneities in multiple environmental media. The joint OPE contribution of wallpaper and wooden floorboard to indoor dust was up to 94.8%, while latex paint and wooden floorboard were the main OPE contributors to indoor air (54.2%) and surface (76.1%), respectively. Risk assessment showed that the carcinogenic risks of tris(2-chloroethyl) phosphate (3.35 × 10–7) were close to the acceptable level (1 × 10–6) and deserved special attention.

We reported a novel method to prepare Al–Si/SiC composites infiltrated under super-gravity field without Mg addition. Noted that centrifugal force acted as the main driving force to overcome the penetration resistance, making it feasible to obtain the Al–Si/SiC composite with high relative density (≥99.3 %). The interfacial reaction between Al and SiC was retarded by Si addition under super-gravity field. Interestingly, the rod-like eutectic Si was detected at Al–SiC interface with semi-continuous distribution, leading to the excellent bending strength (342.6 ± 1.0 MPa), enhanced thermal conductivity (173 W/m K at 373 K), and relatively low coefficient of thermal expansion (8.90 × 10−6 K−1ranged from 323 to 373 K). The interfacial regulation and fracture mechanism were discussed in details.

The aim of this study was to reduce the number of defects, refine the grain size, and improve the mechanical properties of Ti–6Al–4V. We investigated the effect of interpass micro-rolling on the microstructures and mechanical properties of Ti–6Al–4V alloys produced via plasma arc additive manufacturing (PAAM). The non-rolled plasma-arc additively manufactured (PAAMed) sample exhibited coarse columnar crystals, basket-weave microstructures, and Widmanstätten structures, while the interpass-micro-rolled PAAMed sample exhibited fine equiaxed crystals and basket-weave microstructures. Interpass micro-rolling could significantly reduce the number density and size of defects during PAAM, and the rolled samples exhibited lower mechanical property anisotropy than the non-rolled samples. Moreover, the rolled sample exhibited a higher yield strength (∼797.66 and 793.45 MPa), tensile strength (∼939.73 and 935.71 MPa), and elongation (∼12.83% and 14.73%) in the X- and Z-directions than the unrolled sample. These enhanced mechanical properties can be attributed to αGBfragmentation, grain boundary strengthening, dislocation strengthening, and a low crack density. The micro-cracks preferentially nucleated around defects in the non-rolled sample, resulting in high crack and defect densities.

We reported the influence of super-gravity field on spatial distribution of eutectic structure in Al-14.5Si alloys. The Al-14.5Si alloys were solidified under normal gravity (1 g) and various super-gravity fields (1000 g, 2000 g, 3000 g, 4000 g and 5000 g, g = 9.8 m/s2), respectively. The results indicated that the homogeneous distribution of eutectic Si could be observed in the core region of the samples solidified under super-gravity field. As the coefficient of gravity increased, the eutectic Si was significantly refined, resulting in the significant enhancement of the mechanical properties. Noted that several iron-rich phases could be observed in the core region under higher super-gravity coefficient. With the formation of the iron-rich phase, the elongation of the alloy decreased slightly. The refinement mechanism of the eutectic structure and the formation mechanism of the iron-rich phase under super-gravity field were discussed in detail.

Titanium alloys have many advanced applications where they are subject to fatigue. Here, we compare the fatigue crack growth resistance and microstructures of TC4-DT alloys fabricated by wire-arc additive manufacturing (WAAM; sample S1) and in-situ rolled WAAM (sample S2) followed by quasi-β heat treatment. Sample S2 had superior fatigue crack growth resistance, which is mainly attributed to its finer defects and finer α phase. The critical size of the defects related to fatigue performance was calculated. The majority of defects in sample S2 were smaller than the critical size, while several coarse defects (∼1.91 mm) were observed in sample S1. Multiple secondary cracks could be detected near the fracture surface in sample S2, leading to long and tortuous fatigue crack propagation paths. Therefore, in-situ rolling can improve the fatigue properties of titanium alloys fabricated by additive manufacturing.

Hydrological connectivity (HC) is a useful framework for understanding hydrological responses to landscape changes. We present herein a novel model (SOFAR) for utility‐scale solar farms (USFs), combining modules of soil moisture dynamics, roof effects of photovoltaic panels (PVs), vegetation growth and landform evolution. By augmenting the model with a DEM‐based HC index, we investigate hydrological behaviors following the construction of a USF in China's Loess Hilly Region. Nine scenarios are designed, to explore the effects of co‐evolving ecohydrology and landscape on soil erosion and HC in USFs deployed in different climates and terrains, by altering the annual precipitation, rainfall frequency, and ground slope. Our results show that the USF considerably increased runoff (99.18%–154.26%) during its operational period, and soil erosion rate (21.4%–74.84% and 25.35%–76.18%) and HC (0.08%–0.26% and 0.47%–0.91%) throughout construction and operational periods, respectively. The highest erosion rates were detected in the PV installation zones and in the areas close to the river channel. We prove the hypothesis that HC is a critical indicator for sediment yield in a USF, and thus the long‐term responses of soil erosion to USF installation and development can be explained in terms of HC. We conclude that USFs may increase soil erosion, mainly by increasing local HC and runoff, and higher background HC may in turn further aggravate the effects of USFs on soil erosion. Our results underscore the importance of including landscape ecohydrologic and geomorphic feedbacks, to improve the environmental impact assessment of USFs. Precipitation and relief amplitude are major controlling factors for soil erosion in utility‐scale solar farms in hilly areasUtility‐scale solar farms may increase soil erosion, mainly by increasing runoff and local hydrological connectivityHigher background hydrological connectivity could aggravate the effects of utility‐scale solar farms on soil erosion Precipitation and relief amplitude are major controlling factors for soil erosion in utility‐scale solar farms in hilly areas Utility‐scale solar farms may increase soil erosion, mainly by increasing runoff and local hydrological connectivity Higher background hydrological connectivity could aggravate the effects of utility‐scale solar farms on soil erosion

ABSTRACTIn the present study, an Al-7075 alloy reinforced with 15 wt-% TC4 (Ti–6Al–4V) was synthesised by hot pressing. The results of transmission electron microscopy suggest that a well-bonded multilayer interface was created, and that the multilayer has the ability to limit crack initiation at the interface. Sintering at 913 K for 0.5 h proved to be the most effective procedure for limiting the sources of cracking inside the multilayer interface, resulting in an enhanced tensile strength and a compressive strength for the composite of 454 and 873 MPa, respectively. The desired multilayer structure and the strengthening mechanism are discussed in detail. This structure provides guidance for the development of new methods for fabricating composites with excellent mechanical properties.

In the present study, an Al-7075 alloy reinforced with 15?wt-% TC4 (Ti–6Al–4V) was synthesised by hot pressing. The results of transmission electron microscopy suggest that a well-bonded multilayer interface was created, and that the multilayer has the ability to limit crack initiation at the interface. Sintering at 913?K for 0.5?h proved to be the most effective procedure for limiting the sources of cracking inside the multilayer interface, resulting in an enhanced tensile strength and a compressive strength for the composite of 454 and 873?MPa, respectively. The desired multilayer structure and the strengthening mechanism are discussed in detail. This structure provides guidance for the development of new methods for fabricating composites with excellent mechanical properties.

Phospholipids fatty acids (PLFAs) in sewage sludge were analyzed to evaluate the variation in the microbial communities during 100 d composting. Pumice was used as an inorganic bulking agent to eliminate the influences of conventional organic materials on the PLFAs analysis result of the sludge. The results showed that the maximal PLFAs content of 407.41 μg g−1VS was presented on Day-10 and the minimal PLFAs content of 207.49 μg g−1VS was detected on Day-100. Bacteria and fungi were mainly the micro-organisms in the thermophilic stage. The number of bacteria distinctly reduced during the curing stage, whereas the abundances of gram-positive bacteria (14:0 iso, 16:0 iso, 17:0 anteiso), pseudomona (18:1 ω7c), actinobacteria (18:0 10-methyl), and fungi (18:3 ω6c (6, 9, 12)) tended to increase simultaneously. Protozoa were detected in the raw sludge and the matured sample, but not presented within the theromophilic period. Culture-dependent method was introduced to verify the results of microbial populations. The numbers of bacteria and fungi reached maximum (3.38 × 1012and 3.31 × 109 CFU g−1 d s, respectively) on Day-10 and then reduced. The number of actinomycetes increased gradually and reached 3.24 × 107 CFU g−1 d s, on Day-100. The results indicated that PLFAs technique is an efficient and convenient method to investigate the variation in the microbial communities during sewage sludge composting.

AbstractPhospholipids fatty acids (PLFAs) in sewage sludge were analyzed to evaluate the variation in the microbial communities during 100 d composting. Pumice was used as an inorganic bulking agent to eliminate the influences of conventional organic materials on the PLFAs analysis result of the sludge. The results showed that the maximal PLFAs content of 407.41 μg g−1VS was presented on Day-10 and the minimal PLFAs content of 207.49 μg g−1VS was detected on Day-100. Bacteria and fungi were mainly the micro-organisms in the thermophilic stage. The number of bacteria distinctly reduced during the curing stage, whereas the abundances of gram-positive bacteria (14:0 iso, 16:0 iso, 17:0 anteiso), pseudomona (18:1 ω7c), actinobacteria (18:0 10-methyl), and fungi (18:3 ω6c (6, 9, 12)) tended to increase simultaneously. Protozoa were detected in the raw sludge and the matured sample, but not presented within the theromophilic period. Culture-dependent method was introduced to verify the results of microbial populations. The numbers of bacteria and fungi reached maximum (3.38 × 1012and 3.31 × 109 CFU g−1 d s, respectively) on Day-10 and then reduced. The number of actinomycetes increased gradually and reached 3.24 × 107 CFU g−1 d s, on Day-100. The results indicated that PLFAs technique is an efficient and convenient method to investigate the variation in the microbial communities during sewage sludge composting.