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•Boride particles have lamellar structure, composed of varied boride phases and B2 phase.•B2 phase exist in curved but not in straight borides, reactions involved during formation are ...different.•Stacking faults is closely related to the transition between TiB2, Ti3B4 and Bf-TiB.•B27-TiB tends to grow alone because of the difficulty of the transition between B27 and other boride structures.
Borides with varied morphologies and structures obtained by changing B content in as-cast Ti-45Al-2Mn-2Nb alloys are investigated. With the increase of B content, morphologies of borides change from curved to straight, and flake shape, ribbon shape, needle/rod shape, and blocky appear in turn. Curved boride particles have a lamellar structure composed of TiB2 and B2 layers, accompanied by the random appearance and distribution of Ti3B4 and Bf-TiB layers. Except for the absence of the B2 layer, straight needle-like and blocky boride particles have roughly the same structure as curved boride particles, revealing that the formation of curved boride particles is accompanied by divorced eutectic with the matrix and internal irregular eutectic, while no eutectics occurs in straight boride particles. The lack of B atoms during solidification in alloys with lower B content results in a less regular structure and higher stacking fault density of curved boride particles compared to straight boride particles in alloys with higher B content. In addition, some needle-like boride particles are observed to have pure B27-TiB structure without intergrowth. The difference in morphologies and structures can be attributed to the difference in formation mechanism and crystallographic structures of the borides.
Sequential deposition has great potential to achieve high performance in organic solar cells due to the resulting well‐controlled vertical phase separation. In this work, double bulk heterojunction ...organic solar cells are fabricated by sequential‐blade cast in ambient conditions. Probed by the in situ grazing incidence X‐ray diffraction and in situ UV–vis absorption measurements, the seq‐blade system exhibits a different tendency from each of the binary films during the film formation process. Due to the extensive aggregation of FOIC, the binary PBDB‐T:FOIC film displays a strong and large phase separation, resulting in low current density (Jsc) and unsatisfactory power conversion efficiency. In the seq‐blade cast system, the bottom layer PBDB‐T:IT‐M produces many crystal nuclei for the top layer PBDB‐T:FOIC, so the PBDB‐T molecules are able to crystallize easily and quickly. Balanced crystallization kinetics between polymer and small molecule and an ideal percolation network in the film are observed. In addition, the balanced crystallization kinetics are favorable toward realizing lower recombination loss through charge transport processes.
A successful double bulk heterojunction is fabricated with a blade coating method, which sheds light on innovative approaches to rationally realize balanced crystallization kinetics for donors and acceptors and further improve the photovoltaic efficiency of organic solar cells.
•Fatigue crack growth of spheroidal and compacted graphite cast irons are studied.•Graphite of cast irons are observed with the help of X-ray microtomography.•The crack propagation rate is larger in ...compacted graphite cast iron than in spheroidal graphite cast iron.•Graphite fracture is the main mode of fatigue crack propagation for the compacted graphite cast iron.
The present paper focuses on the fatigue life of a Compacted Graphite cast Iron (CGI) as compared to a Spheroidal Graphite cast Iron (SGI). Fatigue crack growth laws have been determined with digital image correlation. Main difference between the materials is that cracks propagate faster in the CGI than in the SGI. X-ray tomography was also used in order to assess graphite morphologies and crack shapes. A complex morphology was observed for the vermicular graphite with rounded edges that limit notch effects. The crack spreads easily in CGI via a quasi cleavage mechanism and by propagating through graphite mainly by breaking the vermicules.
The purpose of this paper is to describe the technique of making casts
using alginate compound for negative and dental stone plaster for
positive impressions. With certain modifications a cast could ...be made
of any part of the body and one can make a museum of interesting cases.
Casts serve as useful teaching material especially in cleft lip and
palate patients to study the effect of surgery on growth and
development of the cleft lip-palate-nose complex in relation to the
remaining face. It also helps in planning reconstruction in cases of
facial defects, recording serial changes in multistage surgery,
pre-operative and post-operative comparison as in rhinoplasty, ear
reconstruction, hand etc; for comparing results before and after
treatment in keloid and hypertrophic scars, fabrication of implants and
preparation of prosthesis. In spite of newer modalities like 3-D
imaging and stereolithography, the usefulness of this old technique in
certain interesting cases can not be denied.
A series of alkyl, alkoxyl, and alkylthio substituted A–π–D–π–A type nonfullerene acceptors (NFAs) IDTCN‐C, IDTCN‐O, and IDTCN‐S are designed and synthesized. The introduction of a lateral side chain ...at the outer position of the π bridge unit can endow the terminal moiety with a confined planar conformation due to the steric hindrance. Thus, compared with nonsubstituted NFA (IDTT2F), these acceptors tend to form favorable face‐on orientation and exhibit strong crystallinity as verified with grazing‐incidence wide‐angle X‐ray scattering measurement. Moreover, the variation of side chain can significantly change the lowest unoccupied molecular orbital (LUMO) energy level of acceptors. As state‐of‐the‐art NFAs, a power conversion efficiency of 13.28% (Voc = 0.91 V, Jsc = 19.96 mA cm−2, and FF = 73.2%) is obtained for the as‐cast devices based on IDTCN‐O, which is among the highest value reported in literature. The excellent photovoltaic performance for IDTCN‐O can be attributed to its slightly up‐shifted LUMO level and more balanced charge transport. This research demonstrates side chain engineering is an effective way to achieve high efficiency organic solar cells.
Steric hindrance of side chains is purposely introduced in the design of planar nonfullerene acceptors. Compared with IDTT2F bearing bare thiophene bridge unit, IDTCN‐C, IDTCN‐O, and IDTCN‐S with alkyl, alkoxyl, and alkylthio substituted thiophene bridge units, all display favorable face‐on orientation and strong crystallinity. An excellent power conversion efficiency of 13.28% based on PBDB‐T:IDTCN‐O is achieved without any additives or annealing treatments.
The article proposes the use of ADI cast iron as an alternative material solution for 30CrMo12 cast steel in the construction of friction systems intended for use in tribocorrosion conditions with ...the presence of an abradant. An independent evaluation of the resistance to tribocorrosion of the analyzed materials was made using two types of tests: a laboratory and industrial one. The industrial test was carried out using an original research stand. It made it possible to map the real operating conditions of the chain wheels of the scraper conveyor transporting a mixture of mineral abrasive and salt water. A standard tribotester with a ball-on-plate system and a model corrosion environment of 3.5% NaCl were used in the laboratory test.
The research results included in the article indicate that ADI cast iron has a higher resistance to tribocorrosion than 30CrMo12 cast steel despite lower initial hardness and similar corrosion resistance. This effect may be caused by the ability to strengthen the near-surface layers of cast iron due to frictional interactions.
The article also showed that the results of the comparative assessment of the tribocorrosion resistance of various materials obtained in the model systems (the laboratory test) can be as effective as the tests of real machine systems (the industrial test).
•Proposition of ADI cast iron as a replacement for 30CrMo12 cast steel for friction nodes in tribocorrosion conditions.•ADI cast iron tribocorrosion resistance was shown to be better than 30CrMo12 cast steel.•The possibility of strengthening the ADI cast iron surface layer in frictional coupling during tribocorrosion.•Analysis of the effectiveness of laboratory and industrial tests in the field of comparative evaluation of materials.•An original test stand was used to test the tribocorrosive wear of scraper conveyor elements under real operating conditions.
The soil microbiome, which is shaped by gut-related activities of earthworms, is affected by microplastic contamination. However, the influence of microplastics on earthworm gut and cast microbiomes ...has been poorly explored. Here, we investigated the influence of microplastics (1% in soil, w/w) on soil physicochemical properties and bacterial communities during gut passage and cast aging of Lumbricus terrestris. Microplastics used in agricultural film production were selected, i.e., low density polyethylene, polylactic acid and polybutylene adipate terephthalate (PBAT). Different niches, including pre-ingestion soil, gut content and aged casts (from 0 to 180 days), were studied. Results showed that microplastics possibly enhanced the gut passage-derived difference between pre-ingestion soil and fresh cast in terms of pH, ammonium, nitrate and nitrite, and dissolved organic carbon. But such effects mostly faded out after 180 days of aging. The composition, as well as the alpha and beta diversity of both the total (DNA) and active (RNA) bacterial communities were decisively shaped by their niche (R2: 0.22–0.63, p < 0.001, PERMANOVA), rather than the presence/absence or the types of MPs. Nevertheless, biomarkers indicative of PBAT treatment were identified, and functional prediction for the active community showed that bacterial communities of this treatment had higher potentials for hydrocarbon degradation (4.9–7.8 times that of the microplastic-free treatment in gut and aged casts). We also identified a “Soil-related core community” and a “Gut-related core community” (contributing to 39.2%–50.2% of the cast microbiome), which possibly neutralized microplastic impacts and maintained the structure and function of bacterial communities during the soil–gut–cast transit. Our findings indicate that the tested microplastics exerted a minor influence on the bacterial communities during the cast aging process, microplastics in aged casts might not necessarily have significant additional influence on the soil microbiome when they are incorporated into soils. Future studies testing different soils, polymers, and earthworm species, under field conditions are recommended to help enhance current knowledge of the influence of microplastics on earthworm cast microbiomes.
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•Microplastics (MPs) influence on the aging of earthworm casts was studied.•MPs affected the physicochemical properties of fresh casts but not in the long term.•PBAT MPs had minor influence on the active community (RNA).•Soil- and Gut-related core communities were likely to buffer the impacts of MPs.•MP-containing casts may not cause additional effects on the soil microbiome.
The earthworm species Lumbricus terrestris L. feeds on plant litter mixed with surrounding soil. Here, we analyzed with a mesocosm approach and soil incubations how that activity and subsequent ...ageing of casts (feces) affects the abundance and diversity of the soil microbiome. Earthworms were fed either with straw of sainfoin (SA, Onobrychis viciifolia; C/N ratio 22) or winter wheat (WW, Triticum aestivum, C/N ratio 101). The gut transit increased the abundances of bacteria and fungi, but reduced archaea. As indicated at the DNA and RNA level, main beneficiaries of the facilitated access to nutrients were members of Bacteroidota, especially Flavobacteriales with an estimated generation time of only 2 h. While Alphaproteobacteria were reduced, Gammaproteobacteria also increased in abundance and activity. SA was more nutritious for L. terrestris, and supported a higher bacterial abundance, probably because more N was available for growth and denitrification. During cast ageing, prokaryotic community compositions became increasingly similar to bulk soil communities. However, they remained distinguishable even after 168 d, suggesting that effects can last beyond a vegetation period. Dry-wet conditions preserved these differences better than continuous moisture. During ageing, more complex prokaryotic networks were detected with WW and dry-wet conditions. Thus, N and water limitations appeared to enhance cooperation rather than competition between the prokaryotes. Overall, this study demonstrates that earthworm soil interactions strongly affect the diversity and temporal dynamics of the soil microbiome. Legacy effects of earthworm activities should thus be kept in mind when investigating the environmental variation of soil microbiomes.
•Earthworm gut transist increases total bacteria and fungi, but decreases archaea.•Inside the gut, Flavobacteriales (Bacteroidota) have a generation time of only 2 h.•Dry-wet cycles preserve cast microbiomes during aging better than constant moisture.•Legacy of earthworm gut transits on soil microbiomes last beyond 168 d of aging.•During ageing more complex prokaryotic networks evolve with N- and water limitation.
Si poisoning on Al-5Ti-B master alloys has been restraining the effectiveness of grain refinement of hypoeutectic Al-Si casting alloys for over 60 years, and yet the underlying mechanism of this ...phenomenon remains unclear. In this work, Si poisoning in Al-Si/Al-5Ti-B system was systematically investigated by combining state-of-the-art electron microscopy, first-principles calculations and thermodynamic calculations. Different from the common belief that silicides coat and therefore poison TiB2, this study demonstrates that the segregation of Si atoms at the TiB2/α-Al interface is likely the cause of Si poisoning. Silicide was found to be thermodynamically unfavorable to form even in an alloy with 10 wt.%Si. On the other hand, an appreciable amount of Si (5–20 at.%) was found to segregate in the TiAl3 two-dimensional compound (2DC) which is critical for triggering the nucleation of α-Al on TiB2. The formation of Ti-Si covalent bond within TiAl3 2DC disturbs its lattice and reduces its chemical interaction with α-Al, which both obstruct the epitaxial nucleation of α-Al and hence leads to Si poisoning. This study suggests that composition engineering of TiAl3 2DC and TiB2 with elements less attractive to Si could be a viable way to mitigate Si poisoning.
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In the present work materials for use in exhaust manifolds of heavy-duty diesel engines were tested in air from 20 to 1000°C with respect to mechanical properties. Two cast irons, SiMo51 and ...Ni-resist D5S, four austenitic cast steels, HF, A3N, HK30 and HK-Nb, and one ferritic cast steel, 1.4509 were studied. The experimental work included thermal conductivity, thermal expansion, uniaxial stress–strain testing, low-cycle fatigue testing up to 30,000 cycles and fractography. Below 500°C, SiMo51 is superior. At higher temperatures, a transition from elastic to plastic strain dominance was observed for the cast irons, reducing their performance. Carbide-forming elements increase heat conductivity and result in a dendrite-like fracture surfaces during fatigue testing. The austenitic steels are superior only at higher temperatures.
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