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The construction industry is a major contributor to CO 2 emissions, accounting for 5–7 % of worldwide CO 2 emissions. Biochar, a carbon-based material derived from waste, is considered an effective way to sequester carbon dioxide. This study investigated the effect of different biochar content on shotcrete under various curing conditions (carbonation, normal and low temperature). Flowability, compressive strength, splitting strength and microstructure of sprayed biochar shotcrete were conducted. Combined carbonation depth, thermogravimetric, and X-ray diffraction (XRD) were used to analyze the carbon sequestration of the biochar sprayed concrete materials from both macro and microscopic perspectives. In addition, the effect of low temperature on the performance of biochar shotcrete was considered. Results show that biochar fills the pores of the concrete and makes the microstructure denser when 5 % biochar replaces cement. Meanwhile, the compressive and splitting strength of concrete has been enhanced. The addition of 10 % biochar has a greater carbon sequestration capacity, although it can somewhat weaken the mechanical properties of concrete. Furthermore, low temperature hurt the performance of concrete. These results demonstrate the potential of combining biochar with shotcrete. It also provides a new direction for improving buildings' overall carbon sequestration performance. [Display omitted] • Effect of biochar content on the mechanical properties of shotcrete was compared. • Carbon sequestration of biochar shotcrete under carbonation curing was analyzed. • Temperature affecting the properties of biochar shotcrete was investigated. [ABSTRACT FROM AUTHOR]

During the pumping of wet shotcrete in a pipe, the aggregate migrates under various forces. In order to investigate the random walking characteristics of particles in slurry pipeline transportation, particle tracking platform for half-open tubes was constructed. Cement-like slurry colloids were prepared. The particle capture function of high-speed camera was utilized to track the particle movement. Random walk theory was used to analyze the transport trajectories of aggregates with different particle sizes. The transport properties of the particles were quantitatively analyzed. The experimental results showed that cement-like slurry colloids were obtained by using a mixture of powder of xanthan gum, carbomer, polyacrylamide and water mixed in a certain proportion. The trajectory of particle transportation in the slurry pipe had a large correlation with the particle size. In a straight pipe, the smoothest particle trajectories were found in the range of 4.17–6.25 % of the pipe diameter. The spectral dimension was positively correlated with tortuosity and more highly correlated with particle size in pipeline transport. The number of spectral dimensions and tortuosity were negatively correlated with axial walking steps of the particles. This paper provided a new way of thinking to study the particle transportation law in concrete pipeline. [Display omitted] • Translucent cement-like slurry colloids were prepared. • The migration characteristics of particles in pipes were quantitatively analyzed. • The effect of particle size on migration using random walk theory was described. [ABSTRACT FROM AUTHOR]

Reducing cadmium (Cd) content from contaminated farmland soils remains a major challenge due to the difficulty in separating commonly used adsorbents from soils. This study synthesized novel millimeter-sized magnetic Fe 3 O 4 /mercapto-functionalized attapulgite beads (MFBs) through a facile one-step gelation process incorporating alginate. The MFBs inherit the environmental stability of alginate and enhance its mechanical strength by hybridizing Fe 3 O 4 and clay mineral components. MFBs can be easily separated from flooded soils by magnets. When applied to 12 Cd-polluted paddy soils and 14 Cd-polluted upland soils, MFBs achieved Cd(II) removal rates ranging from 16.9% to 62.2% and 9.8%–54.6%, respectively, within a 12-h period. The MFBs predominantly targeted the exchangeable and acid soluble, and reducible fractions of Cd, with significantly enhanced removal efficiencies in paddy soils compared to upland soils. Notably, MFBs exhibited superior adsorption performance in soils with lower pH and organic matter (OM) content, where the bioavailability and mobility of Cd are heightened. The reduction of Cd content by MFBs is a sustainable and safe method, as it permanently removes the bioavailable Cd from soil, rather than temporarily reducing its bioavailability. The functional groups such as –SH, –OH, present in attapulgite and alginate of MFBs, played a crucial role in Cd(II) adsorption. Additionally, attapulgite and zeolite provided a porous matrix structure that further enhanced Cd(II) adsorption. The results of X-ray photoelectron spectroscopy suggested that both chemical precipitation and surface complexation contributed to Cd(II) removal. The MFBs maintained 87.6% Cd removal efficiency after 5 regeneration cycles. The surface of the MFBs exposed new adsorption sites and increased the specific surface area during multiple cycles with Cd-contaminated soil. This suggests that MFBs treatment with magnetic retrieval is a potentially effective pathway for the rapid removal of Cd from contaminated farmland soils. [Display omitted] • Soil Cd can be rapidly removed by MFBs recovery from soil. • MFBs treatment reduced Cd in soil by 9.8%–62.2% within 12 h in 26 farmland soils. • The removal of Cd by MFBs is more favorable under low soil pH and organic matter conditions. • Chemical precipitation and surface complexation are main Cd removal mechanisms. • MFBs maintain 87.6% of initial Cd removal efficiency after five regeneration cycles. [ABSTRACT FROM AUTHOR]

No consensus had been reached about the optimal treatment for syndesmotic fixation. We performed a review of randomized controlled trials (RCTs) to assist in clarifying many of the controversies that were debated for years despite new technology and options. PubMed, Embase, and the Cochrane Library were searched through specific terms and limits. Only RCTs were selected for final inclusion. Study screening and data extraction were performed independently by 2 reviewers. Thirteen RCTs, including 828 cases, met the inclusion criteria and are summarized in this review. Pooled results demonstrated that dynamic fixation had better functional outcomes as well as lower rates of malreduction and complications compared with syndesmotic screw fixation. Both absorbable screw and tricortical screw fixation showed similar results to quadricortical metallic screws. Therefore, dynamic fixation is recommended for the treatment of syndesmosis injuries. [ABSTRACT FROM AUTHOR]

Objective To evaluate the efficacy and safety of tranexamic acid (TXA), we conducted a systematic review and meta-analysis of studies on intravenous TXA in posterior lumbar interbody fusion (PLIF) in adults. Methods We searched databases, including PubMed, EMBASE, and the Cochrane Library. The included articles, limited to English, compared intravenous TXA with placebo in adults who underwent PLIF. The methodologic quality of the studies was assessed using the following parameters: heterogeneity, weighted mean difference (WMD), relative risk, 95% confidence interval (CI), and subgroup analysis. Results Seven studies (5 randomized controlled trials and 2 nonrandomized controlled trials) were included in which 529 patients were treated by PLIF. We found that intravenous TXA can reduce total blood loss (WMD = –172.04, 95% confidence interval [CI] −204.70 to –139.37), intraoperative blood loss (WMD = –83.10, 95% CI −117.61 to –48.60), and postoperative blood loss (WMD = –83.10, 95% CI −117.61 to –48.60) but cannot reduce the blood transfusion rates (relative risk = 0.39; 95% CI 0.21–0.72). High-dose TXA could more effectively reduce the blood loss than the low-dose TXA. The risk of thrombotic events was not observed. Conclusions This meta-analysis showed that intravenous TXA can significantly reduce surgical blood loss and patients treated with TXA did not have a significant decrease in transfusion rates. Furthermore, it is safe and does not increase the risk of thrombotic events. We recommend intravenous TXA and the use of high-dose TXA during PLIF in adults. However, more high-quality and large-sample studies will be needed to confirm this result. [ABSTRACT FROM AUTHOR]

Objective The giant calcified herniated thoracic disc (HTD), a rare disease, is a challenge for surgeons because of its complications. This review aimed to confirm the surgical treatment, including surgical approach, results, and complications of HTDs. Methods This systematic review of the literature complies with the PRISMA guidelines and involves a search of PubMed, Embase, and the Cochrane Library for all papers describing surgical treatment of giant calcified HTDs in ≥3 patients. Data on the surgical approach, change in neurologic impairment, and complications were extracted from the search results. Results A total of 11 studies, including 164 patients with giant calcified HTDs that met the inclusion criteria, were included in this systematic review. Of the 164 patients, 145 had myelopathy in giant calcified HTDs, and 8 surgical approaches were included. After the surgical treatment, the neurologic grades were improved in 69% of patients, remained unchanged in 22% of patients, and worsened further in 3% of patients at the final follow-up. Also, of the total patients analyzed, 3% had permanent neurologic deterioration, 4% patients had subarachnoid–pleural cerebrospinal fluid fistula complications, 30% had other complications, 4% had reoperation via transthoracic approach, 13% had permanent neurologic deterioration via the posterolateral approach, and 25% had permanent neurologic deterioration via the thoracoscopy approach. Conclusions Surgical treatment can improve or stabilize neurologic impairment for most patients with giant calcified HTDs. We thus recommend the anterior thoracotomy approach for giant calcified HTDs because of the theoretical advantages over other approaches and the low rate of neurologic deterioration, subarachnoid–pleural cerebrospinal fluid fistula, and reoperation. Highlights • In total, 11 studies and 164 patients with the giant calcified HTDs were included. • Eight surgical approaches used to treat the giant calcified HTDs; 60% were treated by the transthoracic approach. • The surgical treatment can improve or stabilize the neurologic impairment for 96% of patients with the giant calcified HTDs. • Anterior thoracotomy approach for the giant calcified HTDs had low rate of neurologic deterioration, CSF, and reoperation. • We recommend the anterior thoracotomy approach for the giant calcified HTDs. [ABSTRACT FROM AUTHOR]

The diffusive gradients in thin films (DGT) technique is recognized to have advantages over traditional techniques. For example, the passive measurement generally follows the principle of metal uptake by plants, and its result incorporates the influences of soil properties, which may make DGT a good protocol for improving soil quality guidelines (SQGs). However, DGT has rarely been applied to assess Cd phytoavailability in soils under greenhouse vegetable production (GVP) systems. In this study, 29 turnips ( Raphanussativus L. ), 21 eggplants ( Solanum melongena L. ) and their corresponding soils were collected from GVP systems in Dongtai and Shouguang, eastern China. Simple linear regression and stepwise regression were performed using the soil Cd content and soil properties to predict the vegetable Cd content. Soil thresholds were derived based on both total and available Cd concentrations. The results showed that total Cd, DGT-measured Cd (DGT-Cd), soil-solution Cd (Soln-Cd) and CaCl 2 -extractable Cd (CaCl 2 -Cd) were all significantly correlated with vegetable Cd. DGT-Cd had the best correlation with turnip Cd. The total Cd threshold values ranged from 4.87 (pH 6.5) to 5.18 (pH 7.5) mg kg −1 for turnips and 14.60 (pH 6.5) to 14.90 (pH 7.5) mg kg −1 for eggplants. These Cd thresholds were higher than the current SQGs. The predicted of turnip Cd by DGT-Cd was not improved significantly by further considering the soil properties. The calculated soil threshold of DGT-Cd was 5.35 μg L −1 for turnips. However, the predicted soil threshold of DGT-Cd for eggplant was improved by including SOM, with R 2 values from 0.53 to 0.70. The DGT-Cd threshold was calculated as 1.81 μg L −1 for eggplant (30.0 g kg −1 SOM). In conclusion, whether DGT measurements are independent of soil properties and preferable for the evaluation of Cd phytoavailability and the generation of soil thresholds remains to be clarified in future research. [ABSTRACT FROM AUTHOR]

Based on single factor and orthogonal experiments, optimal fermentation conditions for longan wine were Saccharomyces cerevisiae strain of Lalvin K D , juice content of 70% and alcohol content of 10°. Sixteen amino acids were detected. Proline, alanine, glutamic acid and aspartic acid contents were relatively high. Sixty-three volatile aroma compounds were identified using solid-phase micro extraction and gas chromatography (SPME-GC). Ethyl lactate content was the highest, followed by octanoic acid ethyl ester, isoamyl alcohol and decanoic acid ethyl ester. Main functional components were polysaccharides. Longan wine polysaccharide (LWP) with molecular weight 10–30 kDa exhibited the highest hypoglycemic and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activities. 10–30 kDa polysaccharides mainly consisted of glucose, mannose, galactose, arabinose, galacturonic acid and glucuronic acid in molar ratio of 167.72:3.38:3.13:3.46:2.33:1. Infrared and nuclear magnetic resonance spectra confirmed that the sugar ring of 10–30 kDa polysaccharides was in the 〈beta〉-configuration. [ABSTRACT FROM AUTHOR]

A dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2)-modified copper phthalocyanine (CuPc) single crystal nanowire field-effect transistor (FET) with gas dielectric was fabricated as an organic gas sensor. This device exhibits the high response and the excellent controllable selectivity at room temperature. Its detection limit for NO 2 , NO, and H 2 S is down to sub-ppm level. Prior to surface modification, the CuPc nanowire FET shows the response as high as 1088% to 10 ppm H 2 S, but only 97.5% to 10 ppm NO 2 . After Ph5T2 modification, the response to 10 ppm H 2 S is decreased by one order of magnitude, but is dramatically improved up to 460% to 10 ppm NO 2 . The responses towards H 2 S and NO 2 respectively for pristine and the modified sensor are higher than those of most reported organic sensors. The gas-sensing results reveal that Ph5T2 modification can transform the selectivity of the sensor from H 2 S to NO 2 . The controllable modulation of gas selectivity is related to the formed organic heterojunctions between CuPc and Ph5T2, where the hole carriers of CuPc nanowire are modulated by these heterojunctions, resulting in the changed adsorption behavior towards different gases. [ABSTRACT FROM AUTHOR]

The formation of stereocomplex (SC) in enantiomeric poly(lactide)s via recrystallization of homocrystals was investigated by using simultaneous wide-angle and small-angle X-ray scattering. When the symmetric blend of poly( l -lactide) (PLLA) and poly( d -lactide) (PDLA) was heated from the glassy state at a slow heating rate (5 °C/min), predominant homocrystals were formed during heating (cold crystallization). Melting of homocrystals and crystallization of stereocomplex occurred almost simultaneously. In this case, the diffusion of PLLA and PDLA chains played an important role in determining the maximum attainable SC crystallinity. The crystallization behavior during annealing at different temperatures (185 °C, 195 °C and 225 °C) and subsequent cooling was further investigated to understand the effectiveness of annealing on the formation of stereocomplex. The stereocomplex content was unchanged during annealing at 185 °C and kept constant during cooling to room temperature. The SC crystallinity increased slightly during annealing at 195 °C and subsequently cooling. On the other hand, the content of SC increased during annealing at 225 °C and increased remarkably during cooling. A possible mechanism considering the diffusion of PLLA and PDLA chains was proposed. [ABSTRACT FROM AUTHOR]

In this work, we report a novel tripe-shape memory (TSM) strategy using glass transition and thermally reversible Diels–Alder (DA) reaction as two distinct switch units in a network. Based on this principle, a series of TSM epoxy materials were facilely prepared through the reaction of a conventional epoxy oligomer, an aliphatic diamine and a diamine DA adduct cross-linker via a one-pot approach. The thermal and thermal dynamic properties of the reversible–irreversible dual cross-linking epoxy network were studied by differential scanning calorimetry (DSC) analysis and dynamic mechanical thermal analysis (DMTA), respectively. The thermal reversibility of DA adduct was revealed by Fourier transform infrared spectroscopy (FTIR). The TSM effect of the epoxy materials was demonstrated and quantitatively studied by DMTA. The development of thermal-responsive DA adduct as a molecular switch provides a new insight into the design and functionalization of multi-shape memory polymers. [ABSTRACT FROM AUTHOR]

A novel strategy for preparation of unsaturated polyester-based functional materials with widely tunable mechanical properties has been reported in present work. The biodegradable and crystallizable poly(butylene fumarate) oligomer (PBF) bearing reactive carbon–carbon double bonds on the backbone was functionalized by Michael addition with furfurylamine (FA), followed by incorporating bismaleimide (BMI) as cross-linker to form a reversibly cross-linked polyester (PBF-FA-BMI). The obtained material was systematically characterized by a combination of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), rheometry measurement, wide-angle X-ray scattering (WAXS) as well as mechanical property testing. The in-situ FTIR and rheology measurements demonstrated the competition process of DA reaction and crystallization for dynamic conditions and isothermal conditions. The characteristic of dynamically chemical structure variation and crystallization behavior provides a possibility to tune the mechanical property of PBF-FA-BMI. By thermal treatment, the structure programming of the material can be facilely achieved, which undergoes from a typically elastomer to plastic. A schematic illustration of thermo-responsive conversion and recyclability is proposed for the cross-linked polyester. [ABSTRACT FROM AUTHOR]

Polymorphism and crystal transition are of great significance for property mediation in polymer materials. Isotactic polypropylene (iPP) with β – crystal has been widely utilized for the preparation of high performance plastics or films. In the present work, the structural evolution of initially isotropic β – nucleated iPP ( β – iPP) during uniaxial stretching at different temperatures was investigated by in–situ X – ray scattering using synchrotron radiation. The wide – angle X – ray scattering (WAXS) results confirmed that the β – crystal transformed either to the mesophase at lower temperature (30 °C) or to the α – crystal at higher temperature (60, 100 and 120 °C) during stretching. An interesting orientation of β – crystal with molecular chains perpendicular to the tensile direction was identified. As revealed by small – angle X – ray scattering (SAXS), cavitation took place in β – iPP stretched at temperatures lower than 120 °C. The size and shape of the cavities were observed by scanning electron microscope. A deformation mechanism of β – iPP combining the crystal transition, cavitation and orientation was proposed. [ABSTRACT FROM AUTHOR]

Long-term vegetable production in plastic shed soil (PSS) and related soil management strategies stimulate the changes of soil properties and the mobilization of selenium (Se), causing risks to environmental soil quality and human health. Nevertheless, whether the greenhouse management (defined by the years of greenhouse vegetable production) and the greenhouse type have a synergistic effect on Se mobility in PSSs subjected to long-term vegetable production is still unclear. This study investigated the joint effects of greenhouse management and the properties of PSS on Se adsorption and desorption in soils collected from solar greenhouses (SG) and round arch plastic greenhouses (PG), which has been continuously cultivated respectively for 20 and 30 years in Tongshan County, Jiangsu Province, East China. Herein, we carried out a field survey coupled with batch experiments to investigate the adsorption and desorption behavior of Se in the SG and PG soils with different years of vegetable production. Results showed that greenhouse management had differentiated effects on soil properties and Se mobility in the two typical PSSs. Compared to the open field soils, long-term vegetable production generally increased soil nutrients (i.e., total P (TP), available P (AvP)), OM and Se desorption in the SG soil, while it significantly decreased Se adsorption in both typical PSSs. The soil pH had a downward trend with the increase of the years of vegetable production. The longer years of greenhouse vegetable production, the less Se adsorption capacity occurred in PSSs with annual decrease rates of 0.48 and 0.24 mg kg−1 yr−1 for the SG and PG soil, respectively, at 1.0 mg L−1 Se addition. Conversely, the ratio of Se desorption of the SG soils increased with longer vegetable production. The results of partial least squares regression (PLSR) explained the differences in Se adsorption and desorption between the SG and PG soil due to the changes in soil properties caused by the greenhouse management and greenhouse type. The fewer Se application is therefore recommended in the SG soils than in the PG soils after long-term greenhouse vegetable production. • The vegetable production in the SG and PG soils was up to 20 or 30 years. • Greenhouse management and greenhouse types combine altered the soil properties. • Long-term vegetable production and greenhouse type jointly affect Se mobility. • Se adsorption in PSSs decreased linearly with the years of vegetable production. [ABSTRACT FROM AUTHOR]

Abstract: The structure evolution of poly(vinylidene fluoride)/poly(butylene succinate) (PVDF/PBS) blends during stretching above the melting point of PBS is investigated by synchrotron-based simultaneous wide angle and small angle X-ray scattering (WAXS/SAXS). Before stretching, PVDF crystallizes into the α-form, whereas the chains of molten PBS locate at the inter-lamellar amorphous phase of PVDF. Crystal transition from α to β of PVDF is observed in all samples during stretching. The morphological transformation from a lamellar structure into a fibrillar structure occurs at low and intermediate strains. With further deformation, a “stretching induced phase separation” phenomenon is observed. The final microstructure of PVDF/PBS blends contains PVDF microfibrils with PBS chains preferentially distributed in the inter-fibrillar region. The PBS molecular weight influences the onset and end strain for the transition. A new “two-step model” is proposed to describe the deformation process. [Copyright &y& Elsevier]

Abstract: The crystalline structure evolution of poly(ethylene succinate) during tensile deformation was investigated by in-situ synchrotron X-ray scattering. Crystal phase transition from α to β form was confirmed to be fully reversible upon stress loading and unloading. An increase of long period was observed during the α–β crystal transition, which was attributed to the increase of both amorphous layer thickness and crystalline layer thickness (lamellar thickness). The crystalline layer thickness was scaled with the fraction of β crystal, and the change of which was in well agreement with the difference in the repeating length along the crystallographic c axis. Both the crystalline layer thickness and the amorphous layer thickness were fully recoverable. A possible molecular model was proposed to visualize the mechanism for the crystal transition and lamellar thickening. [Copyright &y& Elsevier]

Abstract: The structural evolution during uniaxial tensile deformation of isotactic polypropylene (iPP) and its blend with olefin block copolymer (OBC) was comparatively investigated by in-situ synchrotron X-ray scattering. Small angle X-ray scattering showed that cavitation in iPP/OBC blend took place at a smaller strain than that in neat iPP. The reorientation of the cavities in iPP/OBC occurred at a lower strain than that in iPP as well. Wide angle X-ray scattering was applied to study the crystal-mesophase transition and the orientation process. Compared to the sharp transition in neat iPP, the mesophase formation and orientation in iPP/OBC blend proceeded gradually. The mesophase content and degree of orientation of iPP matrix in iPP/OBC blend were much lower than that in neat iPP within the investigated strain range. By the combination of scattering results and morphological observations, a deformation mechanism based on strain distribution and fracture mechanics was proposed. [Copyright &y& Elsevier]

Abstract: Formation of stereocomplex crystals (sc-crystals) of poly(l-lactide)/poly(d-lactide) (PLLA/PDLA) blend has been recognized as a unique opportunity to dramatically improve the heat-resistant of poly(lactic acid) (PLA). In this study, we investigated the dynamic formation and transition of sc-crystals in PLLA/PDLA drawn film with a combination of in-situ synchrotron wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). The correlation between sc-crystals content and the competing formation of α crystals (stable phase of PLA) in homopolymers during continuous heating and cooling processes was also studied. It was found that at room temperature, the original PLLA/PDLA drawn film consisted of only α crystals, however, with temperature increasing, two populations of sc-crystals were formed at different temperatures from the oriented amorphous region and the molten α crystals in the highly-oriented sample, respectively. Furthermore, new types of sc-crystals and α crystals with the orientation perpendicular to the original sc-crystals were formed during subsequent cooling process. On the basis of the X-ray scattering and DSC data, a schematic model for crystallization and oriented variation concerning sc-crystals and α crystals was proposed. [Copyright &y& Elsevier]

Abstract: The mesophase separation and crystallization as well as the elastomeric properties of olefin multi-block copolymers (OBCs) are studied. The solid state morphologies of the OBCs are determined by the competition between mesophase separation and crystallization of hard blocks. The OBC with lower ΔC8 (octene content difference between soft and hard blocks) displays a spherulitic superstructure, while the OBC with higher ΔC8 exhibits mesophase separation. The two OBCs show very different elastomeric properties. Wide-angle X-ray scattering shows that the two OBCs have different deformation mechanisms. It is proposed that the cooperative deformation of crystalline phase makes an important contribution to the elastomeric properties. [Copyright &y& Elsevier]

• Migration characteristic of particles was investigated in concrete flow. • Factors that affect particle migration were explored. • Effect of particle shape on particle migration was investigated. • Flow induced particle migration was discussed based on shear, gravity and wall effect. During pumping fresh concrete pipes, aggregate migration is occurred under the action of various forces. In order to study the migration characteristic of aggregates during concrete flowing in pipes, in this paper, we built the test system based on particle tracking technology. Transparent concrete was prepared. The particle capture function of high-speed camera was used to track particle motion. Results showed that the radial displacement of particles depended on the initial location and aggregate size. Small aggregates near pipe wall or center axis had fewer motion. For the particles with larger diameter, the migration direction almost pointed to the axis of pipe. The migration displacement of nature aggregates was smaller than that of ground grinding ball. The migration displacement firstly increased and then decreased with increasing the diameter of particle. Moreover, the effect of particle shape on migration was explored. Finally, the wall effect, gravity induced particle migration and shear induced particle migration were compared based on the phenomenon of flow induced particle migration, results showed that the phenomenon of shear induced particle migration played the main role in the formation of lubrication layer. This study was of great significance to reveal the transport law of dense particle flow in the pipeline. [ABSTRACT FROM AUTHOR]

• Various rheology models of fresh concrete were summarized. • Methods used for rheological measurement were described. • Relationship between rheology and shotcrete was analysed. • Challenges of rheology to shotcrete were discussed. In the last decades, significant advances have been made to investigate the rheology of fresh concrete. It was generally accepted that rheology plays a key role in the estimation of concrete workability. However, the application of rheology on shotcrete is relatively few. Thus, this paper tries to make a link between the rheology and shotcrete application. In the first part, various rheology models of fresh concrete were summarized. The characteristics and application scope of rheological models are discussed. In a second part, methods allowing for the measurement of the yield stress and plastic viscosity with or without the use of a rheometer were described, along with the corresponding transformation equations. The methods of avoiding imprecise translation were put forward. In the third part, the relationship between rheology and shotcrete was analyzed, which could be considered as practical tools allowing for the prediction of pumpability and shootability of fresh concrete. [ABSTRACT FROM AUTHOR]

• Support mechanisms for thin spray-on liners (TSLs) are summarized. • The effect of high humidity on the bond of TSLs to granite is investigated. • Bond failure modes at the TSLs-granite interface were analyzed. • The effect of high humidity on the mechanical properties of TSLs was studied. • The pore structure of TSLs at high humidity was observed. Thin Spray-on Liners (TSLs) are a novel rock support technology used in underground projects, which often encounter harsh environments such as high humidity. The mechanical properties of TSLs are affected by the high humidity environment. This study aims to summarize the support mechanisms of TSLs and evaluate the effects of humidity on their performance. Two cement-based TSLs were prepared. They used vinyl acetate-ethylene copolymer emulsion (VAE emulsion) and polyacrylate emulsion as modifying materials, respectively. Specimens were subjected to four different humidity environments for 7 days. The mechanical properties of the specimens were evaluated through compressive, flexural and pull-out tests. The impermeability test was utilized to test the sealing of TSLs. Microscopic observation was conducted using a Lecia microscope. The study also analyzed the interfacial failure modes observed in the pull-out test. The results indicated that increasing humidity hindered the film formation reaction of TSLs, preventing the formation of a continuous three-dimensional spatial polymer mesh structure. Instead, cohesive large particles were formed, negatively impacting the mechanical properties. Additionally, increasing humidity led to the formation of large pores and crack lines within TSLs, further decreasing their mechanical and sealing properties. The increase in humidity also weakened the dry shrinkage effect of TSLs, resulting in increased bond strength. Therefore, analyzing the initial mechanical properties of TSLs under high humidity conditions is crucial for guiding their application in underground projects. [ABSTRACT FROM AUTHOR]

Effect of alternative thrust (shock) and shear on concrete flow in pipes. • Effect of pump and spray process on rheology of concrete was investigated. • Mechanism of pump and spray process affecting concrete rheology was expounded. • Prediction models of the changes of concrete performance were built. • Influence degree of wet-mix shotcrete process on concrete rheology was analyzed. Wet-mix shotcrete mainly includes two processes: pumping and spraying. In this study, to explore the effects of the pumping and spraying processes on the rheological properties and air content of concrete, a full-scale experimental system of wet-mix shotcrete was developed with the given work parameters of these processes. The rheological parameters, slump, and air content of the fresh concrete were measured before pumping, after pumping, and after spraying, respectively. In general, the air content decreased after pumping, whereas the flow resistance declined after pumping and then increased after spraying. These changes were linked to the shear and shock caused by the pumping or spraying process. Under the interference of the pumping and spraying processes, prediction models of the changes in concrete properties were developed. Finally, a one-way analysis of variance (ANOVA) was conducted to analyze the degree of influence of the pumping and spraying processes on concrete properties. This work could be beneficial for further improvement of the understanding of the overall wet-mix shotcrete material and processes. [ABSTRACT FROM AUTHOR]

• A summary of the hotspots of biochar cementitious material is provided. • The carbon sequestration mechanisms of biochar cement-based materials are analyzed. • The properties of biochar cement-based materials are introduced. • The greener capabilities of biochar cement-based materials are reviewed. In recent years, carbon emissions from cement production and agricultural waste treatment have been increasing year by year. Biochar, as a derivative of agricultural waste, provides the possibility of reducing the carbon emissions of cement-based materials. Biochar has a rich pore structure, and after being added to cement-based materials, it accelerates the hydration of cement, promotes the absorption of CO 2 by cement itself, and achieves dual carbon sequestration of biochar and cement-based materials. This article summarized the latest research progress through big data analysis and interdisciplinary work, providing guidance for the research of biochar cement-based materials. The mechanical properties, workability, durability, and carbon fixation performance of biochar cement-based materials were analyzed. In addition, the synergistic mechanism of biochar and cement carbonization reaction and their impact on the carbon capture capacity of cement-based composite materials were studied. In order to better determine the application of cement-based materials in energy conservation and emission reduction, the concept of circular economy was introduced, and the total CO 2 emissions and economic value of biochar cement-based materials were quantitatively studied. [ABSTRACT FROM AUTHOR]

[Display omitted] • The rheological parameters of the test group first decrease and then increase. • The rheological parameters obtained by different operating modes vary greatly. • The operating mode of step change is considered as the optimal mode of rheometer. An appropriate amount of air-entraining agent improves the wet shotcrete fluidity, and the accurate measurement of rheological parameters accurately expresses the rheological characteristics of sprayed concrete. In this paper, eBT2 rheometer was used to measure time variation of rheological parameters of high air content wet shotcrete (HACWS). At the same time, in order to investigate measurement accuracy of shotcrete rheology, the influence of rheometer operating modes (OM) on rheological parameters was studied. This paper selected four rheometer OM to comprehensively analyze the rheological characteristics and rheometer measurement accuracy of HACWS. The results showed that relative plastic viscosity (RPV) and relative yield stress (RYS) of HACWS both tended to decrease first and then increase with time. The torque measured by eBT2 rheometer remained constant at high shear rates. The rheological parameters obtained with different OM differed significantly, and OM-B was recommended to analyze the rheological properties of fresh concrete. This paper provides a reference for the selection of air-entraining agent type and rheometer OM. [ABSTRACT FROM AUTHOR]

The formation of trigonal Form I′ crystals of polybutene-1 (PB-1) directly from melt has drawn much attention in past decades. In this study, we investigate the fractionated crystallization behavior of PB-1 within droplets formed by blending PB-1 with an excess of isotactic polypropylene (iPP) employing DSC, SEM, in situ synchrotron WAXD and FT-IR. When PB-1 is dispersed into a large number of small size droplets, the heterogeneous nucleation of Form II crystals can be inhibited because the number of droplets is larger than that of active nucleation sites for Form II (i.e., active heterogeneities originally present in bulk PB-1). The nucleation of the finely dispersed PB-1 droplets does not occur homogenously, but at the interface with the iPP matrix, which induces the crystallization of the droplets into Form I′. The crystallization rate of Form I′ at different temperatures was determined by Fourier transform infrared spectroscopy. It was found that trigonal Form I′ crystallizes faster when the content of PB-1 in the blend is lower, and the specific interfacial surface area is larger. The opposite effect has been observed for the kinetics of the metastable Form II formation. It is therefore suggested that Form I′ crystallization is driven by the nucleation of PB-1 at the crystalline iPP surface, which competes with the crystallization of Form II induced by nucleating heterogeneities present in PB-1 droplets. [ABSTRACT FROM AUTHOR]

[Display omitted] • Property and bioactivity of pitaya stem polysaccharide (PSP) from six extraction methods were comparatively evaluated. • Based on the exponent v of S2 z 1/2 = f(M w) and its U-shaped curve, six PSPs were highly branched macromolecules. • PSP extracted by ultrasound existed as a more compact sphere-like conformation than that of the other PSPs. • PSP extracted by hot water had the best antioxidant and hypoglycemic activities in vitro than that of the other PSPs. Processing conditions can change the compositions and microstructures of polysaccharides, resulting in favorable and unfavorable effects on their chemical characteristics and bioactivites. Here, this study comparatively evaluated the effects of the commonly used hot water, alkaline, acidic, enzymatic, ultrasonic and hot water-alkaline extractions on the structural features and antioxidant and hypoglycemic properties of pitaya stem polysaccharides. Nuclear magnetic resonance spectroscopy showed six polysaccharides had similar glycosyl types. Scanning electron microscopy exhibited the surface morphology of the extracted six polysaccharides differed significantly. Polysaccharide obtained by hot water showed better antioxidant and hypoglycemic properties than that of the other polysaccharides. These data suggested that alkaline, acidic, enzymatic, ultrasonic and hot water-alkaline extractions have various influences on the degradation of polysaccharides without varying the major structure in comparison with hot water extraction. Additionally, monosaccharide composition and molecular weight of polysaccharides are two chief factors affecting the bioactivity of pitaya stem polysaccharides. [ABSTRACT FROM AUTHOR]

The formation mechanism of the crater-like surface of biaxially oriented polypropylene (BOPP) film remains controversial. To clarify this issue, in this work, three isotactic polypropylene (iPP) samples with different tacticities are selected to prepare BOPP films. It is shown that the relative β crystal content (k β) in the cast sheet increases with tacticity. The β crystal transforms to the α crystal when stretched at 145 °C along the machine direction. For all the samples, rough surfaces are obtained even if the k β value of the cast sheet is very low (k β < 0.1). The arithmetic mean roughness (R a) of the BOPP films increases with the increase of the k β in the cast sheet. While higher k β in the iPP cast sheet contributes to a higher R a value, the β crystallites hinder the enlargement of roughening rings, and cause surface defects (cavitation), which are detrimental to applications. Our results indicate that the β crystal in the cast sheet is not essential for the crater formation and a higher β crystal content is not always beneficial for BOPP capacitor films. [Display omitted] • Correlation between the β crystal in cast sheet and surface roughening of BOPP films was reexamined. • The β crystal content in iPP cast-extruded sheet increased with the tacticity of iPP. • Cavitation occurred during the uniaxial stretching of the iPP cast sheet with a high k β (k β = 0.43). • The β crystal in the cast sheet is not essential for the crater formation in BOPP film. [ABSTRACT FROM AUTHOR]

• A two-dimensional model considering bubble growth, the interaction between pressure and radiolytic gas bubbles, solution movement and the influence of liquid level changes is proposed to predict transient pressure and power pulses during the nuclear criticality in the fuel solution system. • Development of a simulation code to evaluation of criticality transients of fuel solution system. • The impact of pressure on the radiolytic gas release and the power pulse is investigated by comparing the predicted results in the IP model and the CP model. • The model considers the influence of pressure change on bubble nucleation, large bubbles formation and growth. The prediction of criticality excursion in fuel solution system has a significant impact on criticality safety analysis. The behavior of radiolytic gas bubbles, which may be influenced by inertial pressure, is crucial for the progression of criticality excursions. A two-dimensional model is proposed to calculating the bubble growth in order to simulate power and pressure in fuel solution system. The model is verified with experiments conducted at the SILENE facility and the influence of inertial pressure on radiolytic gas bubbles is analyzed by comparing the calculation results with and without the consideration of pressure changes. The comparison results indicate that pressure initially slows down the rate of power decline, while it speeds up the rate of power decline in the later stage of power decrease. Neglecting the pressure change during fast pulse transients may leads to a significant underestimation of the energy in the first burst. However, as the maximum inverse period of those experiments decreases, this underestimation becomes less significant and may even be overestimated slightly in turn. [ABSTRACT FROM AUTHOR]

• Development of a new type of insulated shotcrete. • Co-insulation of silicone rubber tubes and shotcrete. • The heat transfer model of the new type of insulated shotcrete was established. In order to solve the high temperature problem faced in underground engineering, a method of laying silicone rubber tubes (SRTs) in the anchor net structure to form a new type of thermal insulation shotcrete with SRTs (SSRT) is proposed in this paper. The mechanical and thermal insulation performances of SSRT are investigated, as well as the correlation between SRTs sizes and compressive strength, splitting strength and thermal conductivity. Results show that SSRT has increased the thermal insulation performance of 44–71% compared with ordinary Portland shotcrete (OPS), and the mechanical performance is affected to varying degrees. Based on the experiments in this paper, the optimal SRTs laying process parameters of SSRT are determined, i.e. SRTs with an outer diameter of 8 mm, an inter diameter of 3 mm and a distance of 8–9 mm between SRTs. This investigation provides a new exploration and theoretical basis for shotcrete support and insulation technology in high ground temperature environments. [ABSTRACT FROM AUTHOR]

Cross-linked Fe(III)-chitosan composite (Fe-CB) was used as the adsorbent for removing perchlorate from the aqueous solution. The adsorption experiments were carried out by varying contact time, initial concentrations, temperatures, pH, and the presence of co-existing anions. The morphology of the adsorbent was discussed using FT-IR and SEM with X-EDS analysis. The pH ranging from 3.0–10.2 exhibited very little effect on the adsorption capability. The perchlorate uptake onto Fe-CB obeyed Langmuir isotherm model. The adsorption process was rapid and the kinetics data obeyed the pseudo second-order model well. The eluent of 2.5% ( W/V ) NaCl could regenerate the exhausted adsorbent efficiently. The adsorption mechanism was also discussed. [ABSTRACT FROM AUTHOR]

The nuclear criticality safety analysis is crucial for the nuclear safety of spent fuel reprocessing plants. Thus, a set of numerical tools with high accuracy and efficiency to predict the criticality and simulate the hypothetical accidents in the reprocessing procedure is of great importance. Among them, this paper focus on the analysis of the storage tank which is used for dissolution and storage of the spent fuel. According to the characteristics of spent fuel solution system, a parallel 3D critical safety analysis tool for fissile solution system, Hydra-TD, is developed. Generally, it contains the cross-section generation model, the three-dimensional space-time neutron kinetics model, and the R-Z two-dimensional heat conduction and radiolysis gas simulation model. The verifications based on the experiments of the SILENE and TRACY facility are conducted. The results show good accuracy of the prediction of the first fission power peak, multiplication time and total fission energy, indicating the reliability of these numerical models. [ABSTRACT FROM AUTHOR]