In order to explore a new way of recycle use of building solid waste, a composite structure with building waste particles constrained by basalt fiber plain woven fabric was proposed. Its mechanical properties and energy absorption characteristics were investigated through quasi-static uniaxial compression test. The impact of the type of building solid waste particles, the size grade of the building solid waste particles, and the number of constrained layers of basalt plain woven fabric on the response process, failure mode, load transfer, and energy absorption was discussed, respectively. The results show that the peak load of waste brick particles (16.54 kN-27.89 kN) and waste concrete particles (17.99 kN-32.33 kN) under the constraint of single-layer basalt fiber plain woven fabric decrease with increasing particle size. Compared with waste concrete particles, although the waste brick particles provide lower peak load at each particle size grade, the latter exhibits a stable plateau stage (the plateau stress range is 0.87 MPa-1.26 MPa) and obvious densification strain (about 0.3), which is an ideal energy-absorbing structure. Increasing the number of constrained layers of basalt plain woven fabric for waste brick particles is able to significantly increase the peak load and specific energy absorption, however, it is not an ideal energy absorption structure due to the lack of plateau stage and obvious densification strain.
Massive reinforced concrete (RC) structure is widely used in long-term damp environments. To improve the concrete durability and reduce the reinforcing steel corrosion, crack width control is more rigorous in massive RC structure. In this paper, the short-term (30 days) temperatures of concrete are measured by the distributed temperature system (DTS) to inverse the thermal parameters using the genetic algorithm (GA), and the long-term (300 days) temperature is predicted by using the calculated thermal parameters. Moreover, thermal stress field considering the creep is calculated based on the eight-parameters-equation, and the parameters were modified by the results of temperature stress test machine (TSTM). Furthermore, a quantitative reinforcement configuration method is proposed on the basis of the predicted thermal stress field, and its feasibility and effectiveness are verified by a sluice pier structure. Finally, the optimal reinforcement scheme obtained was selected by the comparisons of the crack width, reinforcement stress and the total cross-sectional area of reinforcement. This article provides a new methodology to design reinforcement configuration for massive RC structure.
In this paper, with sulfuric acid as a catalyst and acetic acid as solution at the temperature of 120 ℃ and refluxing period for 24 hours, a sterically hindered bulky 9,9-diarylfluorene intermediate of [9-(4-anilino)-9-phenyl-fluorene] had been successfully designed and synthesized with Friedel-Crafts reaction. The molecular structure of this compound was characterized in detail with nuclear magnetic resonance hydrogen spectrum, mass spectrometry, infrared ray, and so on. Nuclear magnetic resonance hydrogen spectrum and infrared ray spectrum of the compound indicated that the characteristic functional group amino of the compound at 6.55 ppm, 3 481 and 3 385 cm-1, respectively. UV-visible and fluorescence spectra properties of 9-(4-anilino)-9-phenyl-fluorene were characterized and discussed preliminarily, respectively. The research results show that the 9-(4-anilino)-9-phenyl-fluorene with bulky steric hindrance effects has four main absorption peaks with wavelength of 243, 257, 298 and 311 nm in dichloromethane solution, respectively. Moreover, with the excitation wavelength of 308 nm, an emission spectrum curve was obtained with wavelength of 300～500 nm, which has the maximum emission peak of 328 nm with a slim peak at about 405 nm and a long tail to 500 nm. The long tail was probably attributed to the interaction of intermolecular hydrogen bonding from aniline. The appropriate scope of fluorescence emission (300~500 nm) make the compound overlap with the absorption spectra of the classic blue material Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium (Ⅲ) (FIrpic) (300~500 nm). It is possible to obtain excellent host materials through proper molecular tailoring and prepare well for high performance light-emitting device. In order to further understand the photoelectric properties of the compound, we used acetonitrile as solvent and tetrabutylammonium hexafluorophosphate as electrolyte, and the electrochemical properties of the compound was characterized with cyclic voltammetry measurements.The onset of the reduction and oxidation potential of the compound are -0.759 and 0.898 V, and the corresponding HOMO and LUMO energy levels are -5.38 and -3.72 eV, which wolud be beneficial to holes and electrons injection/transportation and further modified to be excellent host materials. All of these data would provide a useful reference for further fabrication of organic semiconductor luminescent device with high performance.
Abstract Cracks often arise in mass concrete structures, due to the thermal stress and low tensile strength of early age concrete. To prevent the undesired thermal stress induced crack, controlling the temperature of concrete has been considered as an effective approach. In this paper, a temperature controlling measure evaluation system (TCMES) is proposed, which includes distributed fiber optic temperature monitoring, prediction of temperature and stress fields, and concrete crack risk evaluation. We first experimentally monitor the temperature evolution of the concrete using the distributed fiber optic temperature sensing. Then thermal parameters of in-situ concrete are retrieved by performing back-analysis. Subsequently, the concrete temperature field and thermal stress field can be predicted from the retrieved parameters and the experimental parameters of concrete. Under the concrete crack risk evaluation principles, temperature controlling measures for different stages are proposed. Our analysis indicates that the proposed system is an effective approach to prevent cracks of early age concrete.
For concrete under short-term loading, effect of reinforcement on concrete crack resistance capability is usually negligible; however, recent research results show that extension of this viewpoint to concrete under long-term loading (temperature variation) may be unsuitable. In order to investigate this phenomenon, this paper presents the experimental and analytical results of early-age reinforced concrete temperature stress development under uniaxial restraint. The experiments were carried out on a temperature stress testing machine (TSTM). Experimental results show that the coupling of reinforcement and concrete creep behavior influenced the concrete temperature stress development, and nearly 16% of concrete stress was reduced in the current research. Moreover, the cracking time of reinforced concrete was also delayed. Finally, based on the principle of superposition, analytical simulations of effect of reinforcement on concrete temperature stress have been performed.
Thermal deformation under restrained conditions often leads to early-age cracking and durability problems in mass concrete structures. It is crucial to monitor accurately the evolution of temperature and thermal stresses. In this paper, experimental studies using temperature stress testing machine (TSTM) are carried out to monitor the generated thermal cracking in mass concrete. Firstly, components and working principle of TSTM were introduced. Cracking temperatures and stress reserves are selected as the main cracking evaluation indicators of TSTM. Furthermore, effects of temperature controlling measures on concrete cracking were quantitatively studied, which consider the concrete placing temperature (before cooling) and cooling rates (after cooling). Moreover, the influence of reinforcement on early-age cracking has been quantitatively analyzed using the TSTM. The experimental results indicate that the crack probability of reinforced concrete (RC) is overestimated. Theoretical calculations proved that the internal stress can transfer from concrete to reinforcement due to creep effect. Finally, the experimental results indicate that the reinforcement can improve the crack resistance of concrete by nearly 30% in the TSTM tests, and the ultimate tensile strain of RC is approximately 105% higher than that of plain concrete with the same mix proportions.
Chalcogenide glass, such as GeSe, has been widely used in the selector device for high‐density vertically stackable memory application due to their nonlinear electrical property. The electronic structure of the valence band, from which the nature of the bonding, the short‐range structure, and the Fermi level can be obtained, is of great importance to understand their unique electrical behavior. However, the surface oxidation issue makes it difficult to obtain the accurate valence band structure by X‐ray photoelectron spectroscopy (XPS). Herein, XPS depth profiles using the combination of the monatomic and cluster ion etching are performed to determine the valence band structures of amorphous Ge–Se films capped with a thin carbon layer. The completely different etching behavior dependent on composition in the depth profiles may be closely associated with the intrinsic bonding configurations of the amorphous films. After obtaining the fresh surface, the intrinsic valence band structures of amorphous Ge–Se samples demonstrate the different bonding behavior and short‐range structure. Most importantly, the Fermi level of amorphous Ge x Se 100− x compounds is also determined.
The full-length cDNA and gDNA sequences of a polyketide synthase gene, termed pks-pa, of Phomopsis asparagi (the fungal pathogen causing the asparagus stem blight), were obtained by RT-PCR, 5'/3'-RACE, PCR and TAIL-PCR. The full-length pks-pa gDNA sequence is 9.336 kb, comprising 5 introns and 6 exons. Sequence alignment revealed a 28-nucleotide difference in polyketide synthase genes between P. asparagi and its closely related species. Phylogenetic analysis indicated that pks-pa is evolutionarily distinct from the polyketide synthases of other fungal species in the same genus. Protein sequence analysis and structural prediction suggested that pks-pa is a hydrophilic protein composed of alpha, beta, turns, coil, alpha amphipathic, beta amphipathic and flexible regions. To confirm the function of pks-pa, a knockout plasmid was used to generate pks-pa knockout transformants in the P. asparagi XT3 isolate. Pathogenic assays showed that loss of pks-pa had no effect on P. asparagi virulence, but significantly reduced pigment production compared with wild-type P. asparagi isolates. These results indicate that pks-pa is required for pigment production, but not P. asparagi virulence.
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