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With the improvement of the quality and performance requirements of duplex stainless steel （DSS） in the industry， secondary austenite （γ2） has become one of the key factors affecting the application of S32750 DSS. Secondary austenite is considered as the joint product of temperature and cooling rates， which performed near K-S or N-W orientation relationship with the ferrite phase and an enrichment for N elements .Secondary austenite can be divided into needle-shaped austenite （NA） and isolated austenite （IA） by morphology. In this paper， the effect of N mass fraction on the precipitation behavior of secondary austenite was studied by preparing test steels with N content of 0.02%， 0.09% and 0.17%. Thermal-Calc simulation and EBSD detection proved that with the increase of N， γ2 evolved from curved feather-shape to needled-shape with the total proportion of austenite phase increased. The precipitation mode of austenite related to the Gibbs free energy， which was namely affected by elements composition and temperature.

In this paper, the research findings on erosion - corrosion of metal materials at home and abroad in recent years were mainly summarized, including research methods of erosion corrosion and external factors affecting erosion corrosion rate. At present, the research methods of erosion - corrosion were mainly carried out in the form of experimental method, supplemented by numerical simulation. The experimental methods primarily included the classification of experimental devices and the collection and characterization of experimental results. Besides, the influencing factors affecting the erosion corrosion rate were classified and compared. The main influencing factors included flow velocity, sand content, sand size， impact angle, liquid pH value, temperature, oxygen content, etc. In the future, the main developing directions of erosion - corrosion would be the following aspects: optimizing the structure of numerical model to predict the erosion - corrosion rate distribution diagram of materials and determining the weak areas of multiphase flow erosion - corrosion.

Duplex stainless steel (DSS) exhibits good mechanical properties and corrosion resistance, and has attracted more and more attention within the fields of both science and technology. However, the increasing levels of N and of Cr, Mo, etc., as alloying elements in DSS increase production difficulty. In particular, the N element increases the risk of Cr2N precipitation, which can seriously deteriorate the thermal plasticity of DSS, while increasing its strength. For this reason, a low-N-content 25Cr-type DSS was designed in order to adapt additive manufacturing processes. With regard to the nano-inclusions of oxide precipitation and effective grain refinement, and considering the benefits of selective laser melting fabrication, a low-N 25Cr-type duplex stainless steel with a 0.09 wt.% N content achieved high mechanical properties, with a yield strength of 712 MPa and an elongation of 27.5%, while the V-notch impact toughness was 160 J/cm2. The microstructure evolution and the reasons behind the improvement in mechanical properties will be discussed in detail. [ABSTRACT FROM AUTHOR]

In estuaries and coastal waters, the flocculation of cohesive sediments is significantly affected by extracellular polymeric substances secreted by microalgae. In this study, laboratory experiments are carried out to explore the role of two typical microalgae (Skeletonema costatum and Cyclotella meneghiniana) on suspended fine‐grained sediments under various turbulent shear and environmental conditions. The results show that the shear rate is a dominant factor in controlling the biomineral flocculation processes, and the existence of microalgae generally enhances the aggregation of mineral sediments with microalgae. It is also found that floc size distributions (FSDs) and mean sizes are clearly influenced by different algal species and concentrations, especially under intensive turbulent environments. Moreover, a quasi‐Monte Carlo (QMC) based bivariate population balance model is developed to simulate the FSDs of sediment‐algae flocs. This model is reasonably validated by two analytical solutions and laboratory observations, and indicates a potential extension for tracking the properties of microalgae‐associated fine sediment flocs due to the discrete nature of the QMC method. Plain Language Summary: The transportation of fine‐grained suspended sediments in estuaries and coastal environments is a factor in many engineering and environmental issues (e.g., siltation, dredging, bed morphology, and water quality). One important characteristic that affects the transport and fate of cohesive sediment particles is flocculation, which is the tendency of particles to aggregate and breakup sequentially to form clusters (flocs) of various sizes, densities, and settling velocities. Since they are abundant in the natural environment, microalgae and their sticky secretions play important roles in the flocculation of cohesive sediment as biological glues. However, few studies have been carried out to reveal the correlation between microalgae and sediment flocculation. Thus, this study aims to investigate the influences of microalgae on the flocculation of cohesive sediment particles in various turbulent environments. We find turbulent shear is dominant in the biomineral flocculation and that biomineral flocs are generally larger than pure sediment flocs. In addition, we develop a bivariate flocculation model to simulate the floc size distribution of biomineral flocs, which is well validated by theoretical solutions and laboratory results. This innovative model offers a preliminary application for multivariate models in biomineral flocculation, which promotes a prospect of future research to develop advanced transportation models. Key Points: The influence of microalgae on the flocculation of cohesive sediments is investigated by laboratory experiments and numerical modelsThe existence of microalgae and their secreted extracellular polymeric substances generally enhances the aggregation of biomineral flocsThe quasi‐Monte Carlo based bivariate population balance model can mimic the biomineral flocculation processes with reasonable accuracy [ABSTRACT FROM AUTHOR]

The formation mode of isolated austenite (IA) formed during high-temperature cooling and its effect on pitting corrosion resistance of S32750 DSS were investigated. As the structure formed during the high-temperature cooling process after hot rolling in S32750 duplex stainless steel (DSS), the precipitation of isolated austenite (IA) can be considered as the combined production of temperature and cooling rates. IA generated at the ferrite (α) grain boundaries or internal α and performed the K-S crystallographic relation with the α N element enriched in IA. The redistribution of elements not only increased the concentration gradient between α/IA, but also reduced the pitting resistance equivalent number (PREN) of original austenite (γ). Scanning Kelvin probe (SKP) and Gaussian fitting proved that with prolonged corrosion time, the potential difference enlarged and local corrosion aggravated. Measured by the weight loss method, pitting resistance decreased to one-third of the solid solution state due to the existence of IA; following, the quantities, sizes, and depth of corrosion pits increased significantly. In addition to α/γ boundaries and α/α boundaries, corrosion pits preferred to initiate around IA. The IA that appeared at α grain boundaries deteriorated the pitting corrosion resistance severely. Furthermore, original austenite with decreased PREN tended to be corroded. In general, the order of pitting occurrence is displayed as follows: α-γ-IA. [ABSTRACT FROM AUTHOR]

In the current information age, having more data means having more information. However, the complete sharing of data will increase the possibility of criminals using relevant data to commit crimes. With the development of cloud computing technology, data sharing can be realized based on the cloud, and the shared data can be stored in the data center. However, this will not ensure the security and privacy of the shared data, and there are security risks such as tampering and counterfeiting of the shared data. The decentralization of the blockchain and the non-tamperable characteristics of the data on the block can safely save data-sharing records without the need for a trusted third party. The paper will discuss the decentralized trusted data sharing technology based on blockchain to enhance the credibility of data sharing. This paper will use the characteristics of the decentralized trust management of the blockchain to study the decentralized solution of trusted data sharing. Aiming at the storage problem of shared data, the block structure of shared data oriented to the blockchain is proposed, and the design is based on the blockchain, and the information of the shared data is stored in the blockchain; in response to the data access request and service problem in data sharing, a block chain-based, decentralized data sharing mechanism is proposed; usingsmart contracts can adopt data variables as parameters to transfer and store the characteristics. Design a decentralized, trusted data sharing smart contract, form a blockchain-based data sharing prototype system, and finally simulate the real on the Ethereum open source platformScenes. The data sharing system based on blockchain was simulated and run on the Ethereum blockchain platform, and the data sharing function test was carried out. Experiments have shown that the blockchain-based data sharing technology solution in a decentralized application environment and distributed storage of data to protect data security, to a certain extent, enhance the credibility of data sharing. [ABSTRACT FROM AUTHOR]

In branching delta channel networks, tides intrude into parallel river outlets causing complex tidal behavior. The tidal motion can impact the division of river discharge over distributary channels. Under some circumstances, the discharge averaged over a tidal cycle may even reverse, drawing ocean water intox the delta, such as observed in the Yangtze Delta, the Fly Delta and the Colorado Delta. Here, we study the flow reversal associated with sediment accumulation of a distributary channel in terms of tidal propagation and subtidal discharge dynamics, by focusing on the Yangtze Delta. The Yangtze Delta channel configuration represents a deep and wide main channel and a smaller side channel that has rapidly accreted over the past decades. A new mechanism is presented, which results in seawater transport across the shallow side channel, posing a risk to freshwater availability. The shallowest section in the side channel nearly acts as a tidal divide. In this section, the tide has the character of a standing wave, which implies that Stokes transport converges from opposite sides of the channel. This leads to significant variation of the total water storage in the side channel and subtidal water levels in the side channel being elevated above that in the main channel. The bulge of water that is stored during spring tide leaves the side channel toward neap tide, explaining reversal of the tide‐averaged discharge and seawater intrusion when the river discharge is low. Key Points: In a width‐convergent delta channel subject to accretion, the shallowest part of the channel may act as a tidal divideStokes transport converges at this tidal divide from opposite sides, which causes subtidal variation of water storage in the channelReversal of the subtidal surface level gradient causes the residual flow to intrude far upstream in the delta [ABSTRACT FROM AUTHOR]

Xu, Y.; Cheng, L.; Zheng, J.; Zhu, Y.; Wu, Y.; Shi, J., and Zhang, W., 2019. Intensive anthropogenic influence on the morphological evolution of estuarine tidal channels. Journal of Coastal Research, 35(6), 1237–1249. Coconut Creek (Florida), ISSN 0749-0208. Long-term and large-scale morphological consequences of human activities are important to consider during human settlement construction around estuarine environments. Thus the rapid human-induced changes in the geomorphology of estuarine areas commands a growing socio-economic and scientific interest. Lingding Bay, a part of the Pearl River estuary, is one of the areas that draws much attention in this respect. By using admiralty charts and topographic maps since the 1960s, decadal timescale morphological changes are investigated to understand the effects of human activities on estuarine tidal channels. The results show that the estuarine channels have undergone overall net erosion over this 50 year period, with a sequence of alternating erosion and deposition phases. On basis of the variations of aspect ratios and thalweg movements, five types of stable channels are identified. The upstream part of the east channel is the most unstable region defined as type 5, where the significant topographical change is principally associated with the unplanned sand mining activities. The whole west tidal channel is approaching relative stability because it was deepened as the main navigational channel, with the thalwegs being straighter. Based on empirical orthogonal function analysis, the anthropogenic effects, including the dredging, sand excavation, and land reclamation, are found to be of relatively major importance in the morphological evolution process of the estuarine channels. [ABSTRACT FROM AUTHOR]

Salt intrusion has some negative impact on the estuarine eco-environment as well as the water resource potential. The paper proposes an analytical model to describe salt intrusion in the estuaries with multiple freshwater sources. The impact of river discharge on the salinity distribution changes along the multiple-fresh-source estuaries, which is different from estuaries with single source of freshwater. Our analytical model is derived from the advection-dispersion equation for salinity while taking into account the hydrodynamic variation along the estuary. In this paper, we take the Humen Estuary, a strongly tide-dominated estuary with two major source of freshwater, as an example to illustrate the model. By testing against eight surveys over a complete spring-neap tidal cycle, the analytical model's capacity to describe salt intrusion in the Humen Estuary is calibrated and validated. The results show that the analytical method can be used to compute the salinity distribution in the multiple-freshwater-source estuaries. In comparison with the field data in the Humen Estuary, the calculated results indicate that the salt intrusion process exhibits remarkable segmentation in the multiple-freshwater-source estuary, although the estuary's inherent characteristic remains the same throughout the estuary. Moreover, by analyzing the multi-segmental features of the Humen Estuary, an efficient and effective model to predict the salt intrusion length of the Humen Estuary is presented and satisfactory results are obtained to illustrate its practical application. [ABSTRACT FROM AUTHOR]

Hot deformation behavior of a Fe-24Cr-22Ni-7Mo-0.5N superaustenitic stainless steel was investigated by hot compression tests in a wide temperature range of 950-1250 °C and strain rate range of 0.001-10 s. The flow curves show that the flow stress decreases as the deformation temperature increases or the strain rate decreases. The processing maps developed on the basis of the dynamic materials model and flow stress data were adopted to optimize the parameters of hot working. It was found that the strain higher than 0.2 has no significant effect on the processing maps. The optimum processing conditions were in the temperature range of 1125-1220 °C and strain rate range of 0.1-3 s. Comparing to other stable domains, microstructural observations in this domain revealed the complete dynamic recrystallization (DRX) with finer and more uniform grain size. Flow instability occurred in the domain of temperature lower than 1100 °C and strain rate higher than 0.1 s. [ABSTRACT FROM AUTHOR]

Zhou, C.Y.; Zheng, J.H.; Dong, P.; Zhang, J.S.; Zhu, Y.L., and Zhang, Z.H., 2016. Tidal evolution in the Yellow and East China Sea during Holocene. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 785-789. Coconut Creek (Florida), ISSN 0749-0208. The impact of the sea level (SL) change on the propagation of tides in the Bohai Sea, Yellow Sea and East China Sea (BYECS) during Holocene was investigated by a 3D numerical model with SL of −60, −30, −15, 0 and +2 m, respectively. Same amplitude and phase of tidal constituents M2, S2, K1 and O1 were applied along the open boundaries in all the cases. The results showed that the number of amphidromic points of M2 increased from 2 to 4 while that of K1 increased from 1 to 2 as the SL rising. Both M2 and K1 co-phase lines rotated anti-clockwise as sea-level rising. S2 shared similar evolution pattern with M2 while O1 evolved similarly with K1. The +2 m SL can have significant influence on the tide pattern. Mainly because the new basin area enlarged, especially the vast area around the Subei and Changjiang estuary, also very near the amphidromes in the south Yellow Sea, which dissipated large amount of tide energy. The new coastline and bathymetry changed the propagation pattern of M2, the tide energy decreased significantly at the north Yellow Sea and Bohai Sea while increased along the Yangtze estuary and Korea west coast. The strong tidal current area corresponded well with the sand ridges during Holocene while weaker tidal current area corresponded with finer muddy deposit, indicating tide force is the dominate factor controlling the bedform generation and sediment distribution in BYECS. [ABSTRACT FROM AUTHOR]

Zheng, J; Zhang, W; Zhang, P, and Zhu, Y., 2014. Understanding space-time patterns of long-term tidal fluctuation over the Pearl River delta, South China. Principal component analyses (PCA) were used to identify the space-time patterns of long-term tidal fluctuation in the Pearl River delta (PRD) region. The tidal levels of the 35 stations over the entire PRD were divided into four regions by the PCA. The results show that different regions display different trends, indicating spatial variability of long-term tidal fluctuations in PRD region. The regional pattern of the first component loadings is mainly located near the outlets. Time series of the factor scores of the the first principal component (PC) shows a significant increasing trend. The regional pattern of the second component loadings is concentrated in the upper part of the PRD region. The factor scores of the the second PC, however, display a significant deceasing trend. The trend in the factor scores of the the third PC of the middle part of the North River is not significant, but it has to face the highest flood risk. As for the upper part of the East River, the factor scores of the the fourth PC also show a significant downward trend that demonstrates that the tidal level shows an obviously decreasing trend in the upper part of the East River. The impacts of the intensive human activities on these changes in the PRD region in the latest three decades are the dominant factor. In particular, the large-scale and long-term sand excavation in the whole PRD region directly results in the riverbed down-cutting, leading to the tidal level in the upper part of the delta decreasing obviously. More tidal prism can enter the delta much more easily also due to the sand excavation, which can fill out the volume not only to keep the tide level, but also even increase the tide level in the middle part of the North River. What's more, intensive reclamation in the estuary is another main factor for tide increase at the outlets of the PRD region. [ABSTRACT FROM AUTHOR]

A facile synthesis of the trisaccharide α-d-mannopyranosyl-(1→2)-α-d-mannopyranosyl-(1→6)-α-d-mannopyranose and the tetrasaccharide α-d-mannopyranosyl-(1→2)-α-d-mannopyranosyl-(1→6)-α-d-mannopyranosyl-(1→6)-d-mannopyranose, the repeating units of fungal cell-wall polysaccharide from Microsporum gypseum and Trychophyton, was achieved using α-(1→2)-linked disaccharide imidate as the donor. The disaccharide imidate was prepared from the self-condensation of 3,4,6-tri-O-benzoyl-1,2-O-allyloxyethylidene-β-d-mannopyranose. [ABSTRACT FROM AUTHOR]

The tetrasaccharide repeating unit of Escherichia coli O9a, α-d-Manp-(1→2)-α-d-Manp-(1→3)-α-d-Manp-(1→3)-d-Manp, and the pentasaccharide repeating unit of E. coli O9 and Klebsiella O3, α-d-Manp-(1→2)-α-d-Manp-(1→2)-α-d-Manp-(1→3)-α-d-Manp-(1→3)-d-Manp, were synthesized as their methyl glycosides. Thus, selective 3-O-allylation of p-methoxyphenyl α-d-mannopyranoside via a dibutyltin intermediate gave p-methoxyphenyl 3-O-allyl-α-d-mannopyranoside (2) in good yield. Benzoylation (→3), then removal of 1-O-methoxyphenyl (→4), and subsequent trichloroacetimidation afforded the 3-O-allyl-2,4,6-tri-O-benzoyl-α-d-mannopyranosyl trichloroacetimidate (5). Condensation of 5 with methyl 4,6-O-benzylidene-α-d-mannopyranoside (6) selectively afforded the (1→3)-linked disaccharide 7. Benzoylation of 7, debenzylidenation, benzoylation, and deallylation gave methyl 2,4,6-tri-O-benzoyl-α-d-mannopyranosyl-(1→3)-2,4,6-tri-O-benzoyl-α-d-mannopyranoside (11) as the disaccharide acceptor. Coupling of 11 with (1→2)-linked mannose disaccharide donor 17 or trisaccharide donor 21, followed by deacylation, furnished the target tetrasaccharide and pentasaccharide, respectively. [Copyright &y& Elsevier]

A highly concise and effective synthesis of the mannose octasaccharide of the N-linked glycan in the adhesion domain of human CD2 was achieved via TMSOTf-promoted selective 6-glycosylation of a trisaccharide 4,6-diol acceptor with a pentasaccharide donor, followed by deprotection. The pentasaccharide was constructed by selective 3,6-diglycosylation of 1,2-O-ethylidene-β-d-mannopyranose with 2-O-acetyl-3,4,6-tri-O-benzoyl-α-d-mannopyranosyl-(1→2)-3,4,6-tri-O-benzoyl-α-d-mannopyranosyl trichloroacetimidate, while the trisaccharide was obtained by selective 3-O-glycosylation of allyl 4,6-O-benzylidene-α-d-mannopyranoside with the same disaccharide trichloroacetimidate, followed by debenzylidenation. The mannose hexasaccharide antigenic factor 13b was synthesized by condensation of a trisaccharide donor, 2-O-acetyl-3,4,6-tri-O-benzoyl-α-d-mannopyranosyl-(1→2)-3,4,6-tri-O-benzoyl-α-d-mannopyranosyl-(1→3)-4,6-di-O-acetyl-2-O-benzoyl-α-d-mannopyranosyl trichloroacetimidate, with a trisaccharide acceptor, methyl 3,4,6-tri-O-benzoyl-α-d-mannopyranosyl-(1→2)-3,4,6-tri-O-benzoyl-α-d-mannopyranosyl-(1→2)-3,4,6-tri-O-benzoyl-α-d-mannopyranoside, followed by deprotection. [Copyright &y& Elsevier]