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Carbon reductant used in metallurgy industry is a considerable source of carbon dioxide emissions. Growing concerns over greenhouse effect have urgently prompted research in the application of hydrogen energy as an alternative. However, some basic kinetic problems in the hydrogen reduction process have not been clarified and resolved yet, such as the activation energy fluctuations caused by neglect of pore characteristics, along with the overly subjective division of the whole reaction process to analyze rate limiting mechanisms. In this study, a novel approach for acquiring instantaneous activation energy is proposed that is able to identify the activation energy at every reaction moment and thereby provide a quantitative basis for kinetics segmentation and rate-limiting mechanism determination. Moreover, due to the space requirements, the activation energy for the reaction stage controlled by nucleation and nuclei growth has a strong correlation with specific surface area. Whereas the restriction mechanisms of chemical reaction and diffusion are closely related to the average pore size. These results reveal that the different pore characteristics and changes in value have a direct influence on the corresponding rate limiting mechanisms and restriction degrees.

This work was aimed to improve the shear strength of disintegrated carbonaceous mudstone (DCM) with nanotalc (NT). A series of direct shear tests were carried out on the NT-modified DCM specimens to determine their shear strengths at various NT concentrations. Subsequently, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to reveal the underlying mechanism which the results showed that shear strength was first increased and then decreased with increasing certain NT concentration. Moreover, the increase in NT concentration also resulted in rise in cohesion and reduction in angle of internal friction. The optimum NT concentration for shear strength improvement of DCM is 4%. This improvement of shear strength is achieved because NT can fill the pores in DCM and its products can bind with particles. This results in formation of large aggregates owing to the small size, strong adsorption capacity and cation-exchange capacity.

Two anthracene-based dyes (MPA-H and MPA-E) with aggregation-induced emission (AIE) and photosensitization characteristics were prepared to obtain solid-state luminophores by photoinitiating the photopolymerization of acrylic monomers with iodonium salt under visible light-emitting diodes (LEDs). The photoinitiating activities of MPA-H/iodonium salt and MPA-E/iodonium salt were evaluated in the photopolymerization of acrylic monomers under 405, 460, and 520 nm LED sources. The aggregation-induced enhanced emission of MPA-H and MPA-E occurred during photocuring. MPA-H and MPA-E showed potential as fluorescent molecular probes to monitor the progress of free radical photopolymerization.

To broaden the application of oxime ester and obtain a photoinitiating system with high performance in visible light photopolymerization, we prepared the two arylaminocarbazole oxime ester (CZ–OXE), OXE1 and OXE2, with visible absorption. The multicomponent initiation systems of OXE as one of the components were evaluated in visible photopolymerization. Synergism between OXEs and diaryliodonium salt (ION), N-vinylcarbazole (NVK), ethyl 4-dimethylamino benzoate (EDB), and triphenylphosphine (TPP) were experimentally studied via steady state photolysis and fluorescence quenching. The thermodynamic feasibility for electron transfer reaction in photoinitiating systems was confirmed by cyclic voltammetry experiments. Electron spin resonance techniques proved the production of active species in the systems. Polymerization experiments under a 405 nm light source showed that the two-component initiation system OXEs/ION was more efficient than the one-component initiator OXEs. Similarly, three-component OXEs/ION/co-initiator photoinitiating systems are more efficient than OXEs/ION systems.

Slopes with carbonaceous mudstone (CM) are widely distributed in the southwest of China and have experienced numerous geological disasters in special climate, especially in rainfall conditions. Therefore, novel materials to stabilize CM slopes have attracted increasing interests. However, developing ultra-stable and cost-effective additives for CM slopes is still a great challenge. Herein, a hydrophobic polymeric material (polyvinylidene fluoride, PVDF) is investigated as an additive to enhance the mechanical strength and long-time stability of CM slopes. The PVDF is uniformly dispersed in CM matrix via interfacial interaction. The contact angle of the PVDF-modified carbonaceous mudstone (PVDF-MCM) can reach as high as 103.95°, indicating an excellent hydrophobicity. The unconfined compressive strength (UCS) and tensile strength (TS) of PVDF-MCM have been intensively enhanced to 4.07 MPa and 1.96 MPa, respectively, compared with ~0 MPa of pristine CM. Moreover, the UCS and TS of PVDF-MCM remain at 3.24 MPa and 1.03 MPa even after curing for 28 days in high humidity conditions. Our findings show that the PVDF can improve the hydrophobicity of CM significantly, which leads to super mechanical stability of PVDF-MCM. The excellent performance makes PVDF a promising additive for the development of ultra-stable, long-lifetime and cost-effective carbonaceous mudstone slopes.

The single-phase polycrystalline copper oxide (Cu2O) films were prepared on sapphire substrates by radio frequency (RF) magnetron sputtering technology which was characterized by low cost and high efficiency. The influences of oxygen flow rate on physical characteristics of the prepared films were investigated. The XRD results showed that the single-phase Cu2O film exhibited a (110) preferred orientation through the analysis of texture coefficient. The AFM images exhibited that the prepared Cu2O film had the highest surface roughness with a distinctive quadrangular surface morphology. The optical transmittance of the single-phase Cu2O film was under 35% and the band gap energy was calculated to be 2.30 eV, the absorption spectra included the peak wavelength of solar radiation and the high absorptivity made it to be a suitable absorbing material. The Hall measurement indicated that all the samples exhibited p-type conductivity. The resistivity, mobility and carrier concentration of the single-phase Cu2O film was 4625 Ω·cm, 1.87 cm2/v·s and 7.227×1014 cm−3, respectively.

In this work, we reported the effects of sputtering power on the structure, optical and electrical properties of InN nanodots prepared on Al2O3 substrate by magnetron sputtering.The results showed that the as-grown InN films exhibited uniform nanodot morphology and the size of the InN nano grains increased with the sputtering power was increased. The InN nanodot exhibited highly c-axis prefered orientation with mainly InN (002) diffraction. The optical band gap of InN samples showed an decreasing trend with the increase in sputteirng power. Moreover, the electrical properties of the InN samples were discussed in detail by hall effect and the carrier concentration and mobility could be adjusted from 3.233×1019 to 1.655×1020 cm-3 and 1.151 to 10.101 cm2/v•s, respectively. These results will lay a good fundation for the applicaion of InN material in the field of gas sensers and light emitting diodes.

Nanotechnology is an extension of sciences and technologies that deal with particles less than 100 nm. This paper reviews previous studies on how nanomaterials work and what their advantages are in subgrade and pavement engineering. In subgrade engineering, the nanomaterials particles can not only improve the physicochemical and mechanical properties of subgrade soils by filling the voids between soil particles but also promote hydration reaction between cement and ion exchange between soil particles. In pavement engineering, the water stability, rutting resistance, fatigue resistance and optical properties of flexible pavements are enhanced by adding nanomaterials into the asphalt mixture. Nanosilica enhances the interface between cement pastes and aggregates and promotes the pozzolanic reaction of concrete, thus, mechanical properties of concrete pavements are improved. Compared with traditional materials, nanomaterials play a promising role in subgrade and pavement engineering, benefitting from their environmental friendliness, lower environmental disturbance, better price/performance ratio and higher durability.

Carbonaceous mudstone is widely distributed in many areas. Its disintegrated material has attracted great interest as a low-cost embankment filler. However, the poor mechanical properties of the disintegrated carbonaceous mudstone (DCM) prevent its widespread application. In this paper, we report the use of artemisia sphaerocephala Krasch. gum (ASK gum) to improve the mechanical properties of DCM. A series of DCM/ASK gum mixtures containing 0 to 8% ASK gum have been prepared and examined by direct shear, unconfined compressive strength, dry-wet cycle, and permeability tests. When 4% ASK gum is incorporated, the unconfined compressive strength of the mixture cured at a duration of 14 days increases by 380%. After 8 dry-wet cycles, the strength of the DCM/ASK gum mixture is 6.4 MPa, which is 12.8 times higher than that of untreated DCM, and the strength retention rate is 61.5% compared to that of 45.5% for untreated DCM. When the normal pressure is 100 kPa, the shear strength increases by 50.0%. In addition, the permeability coefficient was reduced to only 15.9% at 96% compaction degree when only 1% ASK gum is introduced. Scanning electron microscope measurements disclose that the ASK gum can cross-link the DCM particles to form a compact and flat structure, which explains the improved mechanical properties. As both DCM and ASK are abundant, low-cost, and environmentally friendly, the mixture with substantially improved mechanical properties can be a very promising filling material for embankment application.

Finding novel photoinitiators with photobleaching properties suitable for long-wavelength LED light sources is important for their potential use in the photocuring ceramic suspensions containing acrylate resin. Two D-π-A-π-D conjugated benzylidene ketones with visible light absorption (TPAK and CZK) were synthesized and evaluated as photoinitiators in the photocuring of acrylate resin and ceramic suspension under blue (460 nm)/green (520 nm) LED sources. Results showed that the two photoinitiators have high photoinitiating activity and can effectively produce thick-layer curing in acrylate resin and ceramic suspension due to their quick photobleaching properties under 460 nm and 520 nm LED light sources. The curing depth of the ceramic suspensions was measured as a function of the concentration of TPAK and CZK and the energy level of the LED light source. Jacob's equation was used to determine the critical energy Ec and depth sensitivity Dp of every suspension with different concentrations of benzylidene ketones.

In order to study on uniaxial mechanical properties of silty-mudstone under impact of temperature and humidity, a series of uniaxial mechanical tests were carried out. According to these tests, uniaxial mechanical indexes (compressive strength, elastic modulus, splitting strength) of silty-mudstone under different temperature and humidity conditions were obtained, and based on which, its change rule was analyzed. The test results indicate that when considering temperature shift only, uniaxial mechanical indexes of silty mudstone exponential decrease with the increase of cyclic times under same mode of temperature shift, decrease with temperature difference under same cyclic times and direction of temperature shift. After soaking, expansion rate and water content of silty-mudstone increases rapidly at the early stage and tends to be gentle at the later stage, uniaxial mechanical indexes exponential decrease with the increase of water content. After simultaneous variation of temperature and humidity, uniaxial mechanical indexes increase with the increase of temperature difference under negative direction of temperature shift, decrease with the increase of temperature difference under positive direction of temperature shift. Under same conditions, compare influence on mechanical properties: simultaneous variation of temperature and humidity> humidity shift only> temperature shift only.

Density criterion for base materials is the most common practice in quality control and quality assurance for pavement construction. However, cases in which the base material has met the density requirement but turned out to be the cause of a premature failure exist. It means meeting the density requirements would not prevent the premature failures from occurring. Field studies indicated that these base materials are found to be either too weak to provide sufficient base support or too brittle, which causes cracks in base layers which in turn leads to secondary damage in other pavement layers. This paper documents the pavement layer moduli obtained from eight forensic investigations spanning 10 years. Falling-weight deflectometer and dynamic cone penetration tests were conducted to determine the layer moduli on sections that were either too weak or too brittle. In some cases, laboratory tests were performed to evaluate the base materials’ reactions to the stabilizers (lime or cement) and base susceptibili...

The theory of temporal average with a moving diffuser for suppressing speckle is realized by the experiment used a rigid PVC sheet and a treated K9 glass controlled by an external motor. By controlling the mechanical vibration of moving diffuser, a good speckle contrast can be achieved without loss of detailed information. The images about the speckle suppression and detailed information can be directly collected by a CCD and processed the digital images by MATLAB. By calculating the velocity of the moving diffusers, speckle contrast can be obtained. The results show that the speckle contrast after the dispose of the rigid PVC sheet and the treated K9 glass can be respectively reduced from 44.09% and 72.44% to 16.88% and 27.20% separately and the method is feasible and effective.

As presented and discussed in this paper, a series of experiments were conducted on cement concrete plates to study the fracture mechanism and failure behavior of cement concrete pavements. Various boundary conditions including a simple support, hinged support at both ends, and one fixed end only were considered. Accordingly, the fracture response and behavioral characteristics of the cement concrete pavement under these different support conditions were comparatively evaluated and the findings are discussed in this paper. From the study results, the corresponding linear fit-functions between the vertical displacements and the rupture loads under different support conditions were formulated.

Rigid concrete pavement slab under various supporting conditions was analyzed by elasto-plastic nonlinear three-dimensional finite element technique. The influences of void size on the stress, and deflection of concrete pavement slabs were investigated and are presented in this study. This research shows that the stress peak value of a loaded slab is approximately two times higher than at the across corner slab. Due to stress concentration, the void area boundary of PCC slabs becomes a fracture boundary, because it eventually ends up as a corner crack. The deflections of loaded slabs grow rapidly when the tire load approaches the center of the slab. As expected, the highest deflection occurred at the location directly below where the tire load was applied. In addition, the deflections increase directly with increases in the void size. ASCE Subject Headings