In order to improve the mechanical properties of dredged sludge, short polypropylene fibers were used as physical reinforcement, while cement and fly ash were used as chemical stabilizers. Different ...mass percentages of fiber (i.e., 0%, 0.05%, 0.1%, 0.2%, 0.4%, and 0.8%), cement (i.e., 15%, 20%, and 25%), and fly ash (i.e., 15% and 30%) were added to dredged sludge at two initial high water contents (i.e., 92% and 120%) and evaluated using physical experiments. The unconfined compression test was performed on samples after curing them for 28 days. The results show that inclusion of cement and fly ash can significantly increase the dry density and reduce the water content of dredged sludge after curing, consequently enhancing the unconfined compressive strength (UCS). It is found that chemical stabilization can increase the stiffness and brittleness of dredged sludge. However, excessively high fly ash fraction in the mix inhibits strength development in cement-stabilized dredged sludge. The inclusion of fiber decreases the initial stiffness and enhances the UCS, strain at failure, and residual strength of dredged sludge. The UCS increases with fiber content and then decreases slightly, with the optimal fiber content being 0.1%. Fiber reinforcement generates a distinct transition zone in the stress–strain curve, which enlarges with increasing fiber content. The contribution of fiber reinforcement to the strength of dredged sludge is more pronounced at relatively lower water content. The inclusion of fiber can temper the brittleness of chemical-stabilized dredged sludge with more ductile behavior by inducing a ‘bridging’ effect. This effect helps in reducing loading-induced cracking of the stabilized sludge.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Contraction of soil during desiccation gives rise to polygon-patterned cracking. This phenomenon was investigated by continuous full-strain measurements on soil sample surfaces using digital image ...correlation techniques. The results show that desiccation cracking was of the mode I variety and can be reliably predicted through strain field analyses: the observed cracking was restricted mostly to high stretching domains. The observed high stretching stems from either external restraint or internal flaws of the shrinking soil. The cracks redistribute the stress in their vicinity and lead neighboring cracks to intersect them mostly orthogonally. As desiccation proceeds, the surface strain field ceases to provide useful information for predicting crack locations. Further analysis indicates that although drying occurs from exposed material surfaces, late-generation cracks actually initiate in the subsurface and express themselves subsequently at the surface. These observations offer insights into the intrinsic mechanisms of drying-induced crack growth in soils.
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•Dynamic process of desiccation cracking is characterized by full-field strain measurement.•Desiccation cracking position can be reliably predicted based on surface strain concentration information.•Desiccation cracks can nucleate in the subsurface and grow upwards.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Systemic therapy is the primary treatment for advanced thymic malignancies. However, there is an urgent need to improve clinical outcome. Personalized treatment based on predictive biomarkers is a ...potential approach to address this requirement. In this study, we aimed to show the correlation between drug sensitivity tests on CTCs-derived organoids and clinical response in patients with thymic malignancies. This approach carries the potential to create personalized cancer avatars and improve treatment outcome for patients.
We previously reported potential treatment outcome prediction with patient-derived organoids (cancer avatars) in patients with pancreatic ductal adenocarcinoma. To further investigate the feasibility of this approach in advanced thymic malignancies, we conducted a study in which 12 patients were enrolled and 21 liquid biopsies were performed.
Cancer avatars were successfully derived in 16 out of 21 samples (success rate 76.2%). We found a sensitivity of 1.0 and specificity of 0.6 for drug sensitivity tests on the cancer avatars, and a two-tailed Fisher's exact test revealed a significant correlation between drug sensitivity tests and clinical responses (p = 0.0275).
This study supports the potential of circulating tumor cell-derived organoids to inform personalized treatment for advanced thymic malignancies. Further validation of this proof of concept finding is ongoing.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
24.
Tensile Strength of Fiber-Reinforced Soil Tang, Chao-Sheng; Wang, De-Yin; Cui, Yu-Jun ...
Journal of materials in civil engineering,
07/2016, Volume:
28, Issue:
7
Journal Article
Peer reviewed
AbstractThe tensile strength of soil is an important mechanical parameter that controls the development of tension cracks. In this study, randomly distributed polypropylene fibers were employed to ...improve soil tensile behavior. Direct tensile tests were conducted on fiber-reinforced soil specimens with different fiber contents and compacted at different water contents and dry densities. Desiccation tests were also performed to evaluate the effectiveness of fiber reinforcement in improving soil tensile cracking resistance. The tensile test results showed that fiber inclusion significantly increased the soil peak strength, reduced the postpeak strength, and changed the brittle tensile failure behavior to a more ductile one. Soil tensile strength increased with the increase in fiber content. The tensile strength of both reinforced and unreinforced specimens decreased with increasing water content and increased with increasing dry density. Moreover, a higher soil dry density showed a more positive effect in mobilizing the reinforcement benefit of fibers. Based on the fiber/soil interfacial interaction mechanisms, the fiber reinforcement benefits on soil tensile behavior were analyzed. A linear relationship was obtained between the fiber reinforcement benefit and the fiber/soil interfacial shear strength. The desiccation test results showed that fiber inclusion significantly decreased soil cracking. The surface crack reduction ratio increased while the average crack width and length decreased with increasing fiber content, suggesting that fiber reinforcement was efficient in impeding soil tensile failure.
Phosphonate esters may be used as flame retardants for flammable polymers, but always face low flame-retardant efficiency and melt dripping. Until now, no remarkable progress was made in solving the ...above two defects, thus tremendously affecting their applications as flame retardants. In current work, from the chemistry viewpoint, we designed and synthesized poly(2-butyne-1,4-diol phenylphosphonate) (PPBP) containing alkynyl group to break through above-mentioned defects. Compared with the corresponding control sample poly(1,4-butanediol phenylphosphonate) (PPBOP) without alkynyl, thermal analysis revealed that residual char of the PPBP with CC bonds increased to 45.0%, much higher than 1.6% for the PPBOP without CC bonds, and greatly increased by 27 folds. Various measurements and kinetic analysis were used to investigate the underlying cause for the leap in charring. It turns out that PPBP was involved in a unique decomposing and crosslinking process upon heating, which played a vital role in the leap in charring for PPBP. The leap in charring might afford polymers better flame retardancy through condensed phase. After incorporation of the PPBP into thermoplastic polyurethane (TPU), burning tests illustrated that PPBP not only endowed TPU with excellent flame retardancy and anti-melt dripping performance, but also resulted in extremely low heat release rate and smoke production rate, correspondingly decreased by 70.7% and 53.9% compared with those of TPU. Various measurements further confirmed that the charring caused by PPBP itself and the enhanced charring of TPU induced by PPBP played a crucial role in the remarkable superior flame retardancy of TPU/PPBP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
It is always a big challenge for fabricating flame-retarded and smoke-suppressed polymers with excellent mechanical properties in fire-safety material field. In this work, novel organic-inorganic ...hybrid nanoparticles named phosphoryl polyethyleneimine amide-layered double hydroxide (PPEIA-LDH) were prepared via a simple reaction process. When the PPEIA-LDH nanoparticles were used to prepare flame-retardant thermoplastic polyurethane (TPU), it was found that a small amount of PPEIA-LDH remarkably reduced the fire hazard of TPU via a typical intumescent flame-retardant mode. Only 6.0 wt% PPEIA-LDH endowed TPU with a limiting oxygen index of 29.0% and a UL-94 V-0 rating, and also reduced total smoke production and total heat release of TPU by 31.6 and 49.9%, respectively, moreover, mechanical properties of TPU did not show any decrease in this case. The analysis for flame-retardant and smoke-suppression mechanisms demonstrated that synergistic charring between the organic component and the inorganic component in PPEIA-
LDH played a crucial role in reducing the fire hazard of TPU. Excellent mechanical properties of TPU/PPEIA-LDH is ascribed to the uniform dispersion of PPEIA-LDH and good interfacial interaction with TPU. This work demonstrates that organic-inorganic hybrid nanoparticle may provide a promising solution for fabricating fire-safety polymers with excellent overall performance.
•Novel phosphorus-containing organic-inorganic hybrid nanoparticles PPEIA-LDH were designed and prepared.•PPEIA-LDH showed highly efficient intumescent flame-retardant effect on thermoplastic polyurethane.•Flame-retardant mechanism of hybrid PPEIA-LDH nanoparticles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cement solidification is a conventional method in sludge treatment. In order to improve the efficiency and sustainability of this process, biochar and polypropylene fibre were utilized with cement in ...this study. Biochar (0%, 2%, 5%, 7%, 10%, 15% and 20%, w/w) and fibre (0%, 0.05%, 0.1%, 0.2% and 0.4%, w/w) at different mass dosages were added to cement‐sludge system at two initial water contents (120% and 150%, w/w). A series of unconfined compression tests were carried out to investigate the effects of biochar and polypropylene fibre on the mechanical behaviour of cement‐solidified sludge. Scanning electron microscopy (SEM) was used to analyse the mechanism of biochar and polypropylene fibre in changing the mechanical properties of cement‐solidified sludge. Experimental results show that the addition of biochar can significantly promote cement hydration and reduce the water content of sludge after curing, thereby compacting the soil and increasing the unconfined compression strength (UCS) of the mixture. Moreover, when fibre contents increase from 0% to 0.4%, the UCS increases dramatically first and then decreases, peaking at 0.1%. The addition of fibre changes the brittle behaviour and improves the ductility of the samples, with residual strength significantly increased. The moisture regulation effect by biochar and the ‘bridge’ effect by fibre may be the key mechanisms to improve the mechanical properties of cement‐solidified sludge.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Desiccation cracking can significantly change the integrity of soils, and potentially result in the instability of infrastructure as well as the migration of contaminants. Biochar is regarded as a ...promising low-carbon material for geotechnical applications, including cracking prevention. This study investigates the effects of biochar particle size and dosage on the desiccation cracking characteristics of a silty clay. For samples with fine biochar particles (<0.25 mm), coarser primary cracks initiate first, followed by finer secondary cracks regardless of biochar dosage. Quantitative analysis of the cracking characteristics at the stable stage shows that the surface crack ratio, the number of crack segments, the total length of cracks and the average width of cracks decreased by 31.29%, 30.78%, 14.18%, and 20.45% after 10% biochar addition. For samples with coarse biochar particles (>0.25 mm), cracks initiate simultaneously on the soil surface, and primary and secondary cracks are difficult to distinguish after drying, especially in high dosage samples. In the presence of 10% biochar, the surface crack ratio and average width of cracks decreased by 28.64% and 62.84%, but the number of crack segments and total length of cracks increased by 163.39% and 42.13%. Microstructure and image processing analysis of soil cracks indicate that biochar affects the crack initiation and propagation process by altering the soil microstructure and thereby the crack parameters. The contact between biochar and soil particles transitions from close contact to loose contact as the size of the biochar particles increases. In general, the application of 10% biochar with fine particle size had the best performance in inhibiting soil cracking.
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•Biochar affects cracking behavior by altering soil microstructure.•Coarse biochar (>0.25 mm) has more loose contact with soil than fine biochar (<0.25 mm).•Fine biochar and coarse biochar induce different cracking behavior of silty clay.•Fine biochar can better inhibit soil desiccation cracking than coarse biochar.•Biochar inhibits cracking by replacing soil particle and occupying shrinkage space.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dredged sludge has poor mechanical properties and its safe disposal is highly risky. Fiber has been considered as an effective additive for soil reinforcement because of its cost effectiveness, easy ...adaptability, and reproducibility. The main objective of this research is to investigate the effects of polypropylene fiber on hydro-mechanical behavior of dredged sludge. A series of compression and direct shear tests were performed on dredged sludge samples with different percentage contents of polypropylene fiber 0%, 0.05%, 0.1%, 0.2%, 0.4%, and 0.8% by weight of dredged sludge and the direct shear tests were performed at vertical stresses of 50, 100, 200 and 400 kPa. The test results indicate that inclusion of fiber improves shear strength of sludge with increasing compression, void ratio, consolidation coefficient and hydraulic conductivity. The optimum fiber content for these improvements was found to be 0.1%. Presumably the post-consolidation moisture content of sludge after consolidation is minimal at this fiber content, although the shear strength continues to increase with fiber content even after consolidation. The shear strength of samples with the fiber contents of 0.8% is 1.48, 1.58, 1.42, 1.27 times that of the non-reinforced samples under respective consolidation pressures of 50, 100, 200 and 400 kPa, and the reinforcement efficiency is most significant under a pressure of 100 kPa. The strain hardening tendency is more pronounced with the increase of fiber content in the late shear failure process. The results of this study indicate that the mechanism of fiber reinforcement for the consolidation test is “bridging” as different from the shear strength test, which is “friction”. This realization should impact upon the failure patterns of fiber reinforced materials.
•Addition of fiber can increase the displacement, consolidation coefficient and hydraulic conductivity of sludge.•The optimal content of fiber for sludge reinforcement tested in consolidation test is 0.1%.•With a fiber content of 0.1%, the post-consolidation moisture content of sludge after consolidation is minimal.•At a given vertical stress, shear strength of fiber reinforced sludge increases linearly with increasing fiber content.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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