Search

With the accelerated urbanization process, the emergence of urban underground integrated pipeline corridors is the trend for cities, especially large and medium-sized cities. However, due to the complexity of the internal system of the integrated corridor, there are various risks in the process of its construction and operation and maintenance, and the risk factors are complex and diverse. In this paper, we introduce ontology technology and knowledge base construction into the risk management of integrated pipeline corridor, build an ontology-based knowledge base of integrated pipeline corridor risk, and construct a Bayesian network based on the established risk knowledge base for risk evaluation of identified risk factors. The combination of ontology knowledge base construction and Bayesian network method of integrated pipeline corridor risk makes the risk identification system completer and more effective, and the method can effectively evaluate the disaster risk level of integrated pipeline corridor operation and maintenance, which can meet the practical needs of integrated pipeline corridor operation and maintenance risk management and disaster prevention and mitigation work.

Quantification of changes in soil organic carbon (SOC) and SOC stock as influenced by fertilization practices is needed for the improvement of carbon (C) sequestration and soil quality. A meta-analysis of 582 paired-treatment data from 95 long-term field experiments published from 1980 to 2012 was used to characterize the changes in SOC under different fertilization treatments and residue management practices in China’s paddy soils. All treatments sequestrated significant amounts of C compared with the control (CK, no fertilizer application). The greatest mean difference in SOC change rates was measured in the NPKM (mineral nitrogen, phosphorus and potassium plus manure) treatment, i.e., 0.401 g kg −1 yr −1 , followed by the M (manure only) treatment (0.36 g kg −1 yr −1 ), while the N (mineral nitrogen only) treatment caused the lowest rate of 0.046 g kg −1 yr −1 . The rates of SOC change in the fertilization treatments with C incorporation (e.g., manure application or straw return) were noticeably higher than those treated with inorganic chemical fertilizers only. The mean difference in the SOC change rates decreased with time and duration of the experiments. The effects of the initial SOC content on the rates of SOC change were not significant, and the effects of SOC accumulation originating from the fertilization treatments depended on the cropping systems. Potential SOC sequestration estimates were more accurate when two factors (sequestration duration and SOC saturation level) were taken into consideration. Our results indicate that the application of manure (e.g., M or NPKM) showed the greatest potential for C sequestration in agricultural soil and produced the longest SOC sequestration duration (45–51 yr).

With the aid of SEM and DTA, the microstructures of metal side of the interface between Ti48Al2Cr2Nb alloy and Y 2 O 3 , ZrO 2 (Y 2 O 3 stabilized), ZrO 2 (MgO stabilized), and Zircon sand were investigated, respectively. The initial reaction temperatures were measured for Ti48Al2Cr2Nb alloy and Y 2 O 3 , ZrO 2 (Y 2 O 3 stabilized), ZrO 2 (MgO stabilized) and Zircon sand, respectively. The results show that the microstructure is the coarsest with rosettes-like shape after Ti48Al2Cr2Nb alloy reacts with Zircon sand, and even the smallest with granular-like shape after Ti48Al2Cr2Nb alloy reacts with Y 2 O 3 . The order of the initial reaction temperatures between Ti48Al2Cr2Nb alloy and four oxide ceramic materials is non-reaction at 1500, 1400, 1380, and 820 °C, respectively.

In term of newly developed titanium alloys Ti-6Al-4V-4Zr-Mo (Ti6441) modified from the commercial Ti-6Al-4V alloys, the adiabatic shear behaviors of equiaxed and lamellar microstructures were investigated. Unlike the Ti-6Al-4V alloys, Ti6441 alloys with the lamellar microstructure are less susceptive to adiabatic shear bands (ASBs), compared with the equiaxed one. In particular, the ASBs branch off in the lamellar microstructure, requiring additional energy by consuming metal bulk plastic deformation work. Besides, forced shearing experiment results show the lamellar microstructure exhibits outstanding dynamic ductility in contrast with the equiaxed one, though both microstructures perform the same strength value.

The electrooxidation of 1,3-butanediol (1,3-BD) on platinum electrodes in perchloric and sulphuric acid solutions was studied by using cyclic voltammetry and in situ FTIR spectroscopy. The determination of intermediates and products involved in 1,3-BD oxidation was carried out in solutions prepared using either millipore water or deuterated water as solvent. The in situ FTIRS data acquired from experiments of single potential alteration and time-resolved determination demonstrated that the oxidation of 1,3-BD on the Pt electrode is a complex process and may obey a dual path reaction mechanism. Three pathways were determined in 1,3-BD oxidation. The first one is the dissociative adsorption of 1,3-BD, which yields CH 3 CHOHCH 3 and poison species CO ad . The second one is the dehydration of 1,3-BD, which produces intermediates of CH 3 CHCHCH 2 OH and CH 2 CHCH 2 CH 2 OH. The last one is the direct oxidation of 1,3-BD at potentials above 0.30 V(SCE) on a Pt surface free of CO ad , which produces intermediates of CH 3 CHOHCH 2 COOH and CH 3 COCH 2 CH 2 OH. These intermediates are characterised by IR bands appearing near 2045 (CO ad ), 1600 (>CC −1 (>CO) and a series of IR bands locating in the fingerprint region and around 3000 cm −1 . All the above intermediates can be oxidised further to acid compounds, among them acetoacetic acid which is characterised by the double carbonyl bands at 1724 and 1712 cm −1 and has been determined as the majority species. As the acid compounds can be oxidised to CO 2 which yields IR absorption at 2345 cm −1 via a C–C bond breaking process at relatively high electrode potentials, they have been considered to play the role of both intermediate and product in 1,3-BD oxidation. The ultimate product of 1,3-BD oxidation at potentials above 0.30 V(SCE) is determined as CO 2 . The comparison of IR features of 1,3-BD oxidation with those of 1-butanol oxidation reported in our previous paper [1] illustrated the effects of molecular structure in electrocatalysis of C 4 molecules.

The modification of platinum electrode surfaces by bismuth and sulfur adatoms was studied using cyclic voltammetry, in situ FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). The apparent coverage of saturation adsorption of bismuth and sulfur on Pt electrode from solutions containing 10−3 M Bi3+ or S2− ions were measured at approximately 0.69 and 0.90, respectively. The in situ FTIR spectroscopic data demonstrated that both sulfur and bismuth adatoms can prevent, by a surface geometric arrangement, the formation of poison species which is identified as adsorbed CO species derived from the dissociative adsorption of HCOOH on Pt electrode. However, a big difference in electrocatalytic activity of Pt/Sad and Pt/Biad electrodes for HCOOH oxidation has been determined. HCOOH cannot be oxidized on a Pt/Sad electrode at the saturation adsorption of sulfur. Nevertheless, when the S adatoms have been partially removed by oxidation at potentials above 1.0 V (Pd/H), the oxidation of HCOOH on the Pt/Sad electrode can take place and yield a larger current than a Pt electrode does in the positive going potential sweep. It has been found that the Pt/Biad electrode at the saturation adsorption of bismuth maintains a high electrocatalytic activity towards HCOOH oxidation, which was determined both in the cyclic voltammetric studies and in the potential step experiments of a relatively long time window. The difference in electrocatalytic properties of bismuth and sulfur adatoms in HCOOH oxidation was attributed to the different chemical states of these adatoms on the Pt electrode surface. It has been revealed by combined studies of electrochemistry and X-ray photoelectron spectroscopy that the ions of S2− can discharge on Pt surface during adsorption forming sulfur adatom under conditions with or without electrochemical polarization. In addition, the adsorbed sulfur adatom is mainly in an atomic state, but charged partially with negative charge. The adsorbed sulfur (Sad) can be oxidized to sulfate species at potentials above 1.20 V (Pd/H). However, the Bi3+ ions in solution cannot be reduced on Pt surface during adsorption. It was determined that 67% adsorbed bismuth was reduced to its atomic state at 0.0 V (Pd/H) and 33% bismuth remained in an oxidized state even at this relatively low potential. A transition oxidized state of adsorbed Bi has been observed from the XPS spectrum recorded near 1.0 V (Pd/H), for which the higher binding energy of Biad appeared near 160 ( 4 f 7 2 ) and 165 eV ( 4 f 5 2 ). At potentials above 1.1 V (Pd/H), all adsorbed bismuth is in an oxidized state. The present study has placed emphasis on the importance of chemical states of electrode surface in electrocatalysis and thrown new insight to understand the origin of electrocatalytic effect of adatoms.

The electrooxidation of 1-butanol (1-BL) on Pt electrodes was studied using cyclic voltammetry and in situ FTIR spectroscopy. The results demonstrated that 1-BL can undergo dehydration to form CH3CH2CH  CH2 in acid solutions. The IR absorption of of the C  C bond yielded a broad band around 1600 cm−1, which has been determined in solutions prepared using both Milli-Q water and deuterated water. Evidence for dissociative adsorption of 1-BL on a Pt surface was given by the appearance of an IR band near 2060 cm−1, which was assigned to IR absorption of linearly bonded CO species. At potentials below 0.30 V(SCE), the dissociative adsorbates accumulated and absorbed stably on the Pt surface to inhibit the oxidation of 1-BL. When the adsorbed CO species started to be removed by oxidation at potentials ≥ 0.30 V(SCE), two strong IR bands near 2345 and 1712 cm−1 appeared in the spectra. The band near 2345 cm−1 was attributed to the asymmetrical stretch of the CO2 molecule which is the product species. The IR band near 1712 cm−1 was ascribed to IR absorption of the carbonyl group, which, together with the IR bands appearing in the fingerprint region, suggested the production of butyric acid in the oxidation of 1-BL. In considering the large intensity of the carbonyl band in spectra obtained at potentials above 0.30 V(SCE), the butyric acid was assigned as one of the product species. Butyric acid has been considered also as an intermediate species involved in 1-BL oxidation, since, at higher potentials (> 0.40 V), butyric acid can be oxidised to CO2, although the complete oxidation of butyric acid to CO2 is rather difficult. The present study demonstrated, at the molecular level, that the oxidation of 1-BL obeys the dual-path reaction mechanism.

The role of the oxidation state of a platinum polycrystalline surface in the electrocatalytic oxidation of C1 to C4 primary alcohols has been studied by using electrochemical techniques, in situ FTIR spectroscopy and X-ray photoelectron spectroscopy. The results revealed that the oxidation state of the Pt surface plays a key role in the oxidation of primary alcohols, and demonstrated that the oxidation of C1 to C4 primary alcohols on a Pt electrode is controlled by the formation of surface oxides on the Pt electrode at different potentials. It was found that the dependence of the reaction process on the oxidation states of the platinum surface yielded similar features in the cyclic voltammogram for oxidation of different primary alcohols at a Pt electrode. According to the effects in the oxidation of primary alcohols, the surface oxides of platinum may be classified as active and poison species. The Pt surface oxides of higher oxidation states (Pt(OH)3 and PtO2) formed at potentials above 1.0 V (SCE) were identified as poison species, while other lower oxidation states of Pt surface oxides such as PtOH, Pt(OH)2 and PtO may be identified as the possible active species for primary alcohol oxidation.

The kinetics of dissociative adsorption of HCOOH on Pt(100), Pt(610), Pt(210) and Pt(110) single-crystal electrodes has been investigated. The oxidation of dissociative adsorbate (DA) derived from the dissociative adsorption of HCOOH was used as a probe reaction together with the potential-step technique of short time windows. The quantity Q ad of DA produced at a given potential E ad and in a defined time window t ad of adsorption has been determined systematically. At fixed t ad peaked curves of Q ad versus E ad in the potential range between −0.25 and 0.25 V/SCE have been obtained on all four electrodes. The maximum rate of dissociative adsorption of HCOOH decreases in the order Pt(110) ⪢ Pt(210) ⪢ Pt(610) ⪢ Pt(100).