Search

Background: Certain bacterial infectious diseases are categorized as notifiable infectious diseases in China. Understanding the time-varying epidemiology of bacterial infections diseases can provide scientific evidence to inform prevention and control measures. Methods: Yearly incidence data for all 17 major notifiable bacterial infectious diseases (BIDs) at the province level were obtained from the National Notifiable Infectious Disease Reporting Information System in China between 2004 and 2019. Of them 16 BIDs are divided into four categories, respiratory transmitted diseases (RTDs, 6 diseases), direct contact/fecal-oral transmitted diseases (DCFTDs, 3 diseases), blood-borne/sexually transmitted diseases (BSTDs, 2 diseases), and zoonotic and vector-borne diseases (ZVDs, 5 diseases), and neonatal tetanus is excluded in the analysis. We characterized the demographic, temporal, and geographical features of the BIDs and examined their changing trends using a joinpoint regression analysis. Results: During 2004‒2019, 28 779 thousand cases of BIDs were reported, with an annualized incidence rate of 134.00 per 100 000. RTDs were the most commonly reported BIDs, accounting for 57.02% of the cases (16 410 639/28 779 000). Average annual percent changes (AAPC) in incidence were − 1.98% for RTDs, − 11.66% for DCFTDs, 4.74% for BSTDs, and 4.46% for ZVDs. Females had a higher incidence of syphilis than males, and other BIDs were more commonly reported in males. Among 0-5-year-olds, the diseases with the largest increases in incidence were pertussis (15.17% AAPC) and scarlet fever (12.05%). Children and students had the highest incidence rates of scarlet fever, pertussis, meningococcal meningitis, and bacillary dysentery. Northwest China had the highest incidence of RTDs, while South and East China had the highest incidences of BSTDs. Laboratory confirmation of BIDs increased from 43.80 to 64.04% during the study period. Conclusions: RTDs and DCFTDs decreased from 2004 to 2019 in China, while BSTDs and ZVDs increased during the same period. Great attention should be paid to BSTDs and ZVDs, active surveillance should be strengthened, and timely control measures should be adopted to reduce the incidence. [ABSTRACT FROM AUTHOR]

[Display omitted] • AOB population was enriched through long-term inhibition of FA on NOB activity. • FNA-dependent response of the biological nitritation process was investigated. • Hellinga model could perfectly describe the nitritation inhibition by FNA. • FNA reduced the Nitrosomonas abundance, but increased the Paracoccus abundance. • Nitrosomonas was the key biomarker indicating the nitritation to FNA constraint. This work comprehensively deciphered the effect of free nitrous acid (FNA) on the microbial community, inhibitory kinetics, and nitrifiers in nitritation process. Nitritation was first successfully achieved through selective inhibition of free ammonia (FA) on nitrite oxidizers (NOB). Then, batch tests clearly showed that FNA significantly inhibits the ammonia oxidation rate (r su) and the growth rate (μ) of ammonia oxidizers (AOB), which was well described by the Hellinga model (K I = 0.222 mg·L−1). The structural equation model indicated that FNA was significantly and negatively associated with r su , μ , Nitrosomonas, Commamons, Nitrospira, and Nitrotoga and positively correlated with Paracoccus. Furthermore, Nitrosomonas significantly drove the ammonia utilization and growth of AOB and was identified as the most important functional biomarker indicating the nitritation in response to FNA levels using random forest model. This study provides helpful information on the kinetics of the mechanism underlying the FNA inhibition on nitrification. [ABSTRACT FROM AUTHOR]

Solid neuroendocrine breast carcinoma (solid NEBC) is a relatively uncommon malignant tumor of the breast. The purpose of our study was to explore the incidence and clinical features of this tumor, and to evaluate the efficacy of adjuvant chemotherapy and endocrine therapy for patients with solid NEBC. Of 7542 breast cancers registered during the period from March 2004 to April 2011, 22 patients (0.29%) who underwent surgery had tumors that were histologically confirmed as solid NEBC, and were enrolled in this study. The age range of these patients was 29-77 years (mean 52.5 years). Patients were staged according to the 7th edition of the pathologic tumor-node-metastasis ( pTNM) staging system. Biopsies or resection specimens were reviewed and reclassified according to the World Health Organization ( WHO) 2003 classification. We recorded clinical features including gender and age, chief complaint, and past medical history, tumor characteristics including size, location, preoperative diagnosis, and pathologic and immunohistochemical findings, the therapeutic schedule, and the follow-up results. Solid NEBC is a rare and distinct category of malignant disease of the breast, with good prognosis, and in most early-stage cases, is resectable. The role of adjuvant chemotherapy and endocrine therapy in solid NEBC may be limited and should be studied further. [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]

This study comprehensively deciphered the effect of silver nanoparticles (AgNPs) on anammox flocculent sludge, including nitrogen removal performance, microbial community structure, functional enzyme abundance, antibiotic resistance gene (ARGs) dissemination, and horizontal gene transfer (HGT) mechanisms. After long-term exposure to 0–2.5 mg/L AgNPs for 200 cycles, anammox performance significantly decreased (P < 0.05), while the relative abundances of dominant Ca. Kuenenia and anammox-related enzymes (hzsA , nirK) increased compared to the control (P < 0.05). For antibiotic resistome, ARG abundance hardly changed with 0–0.5 mg/L AgNPs but decreased by approximately 90% with 1.5–2.5 mg/L AgNPs. More importantly, AgNPs effectively inhibited MGE-mediated HGT of ARGs. Additionally, structural equation model (SEM) disclosed the underlying relationship between AgNPs, the antibiotic resistome, and the microbial community. Overall, AgNPs suppressed the anammox-driven nitrogen cycle, regulated the microbial community, and prevented the spread of ARGs in anammox flocs. This study provides a theoretical baseline for an advanced understanding of the ecological roles of nanoparticles and resistance elements in engineered ecosystems. [Display omitted] • AgNPs effects on anammox flocs were comprehensively deciphered. • AgNPs inhibited anammox performance and regulated the microbial community. • The antibiotic resistome significantly decreased (> 80%) with 1.5-2.5 mg/L AgNPs. • AgNPs effectively prevented the MGE-mediated HGT of ARGs. • Ca. Kuenenia was found to be the potential host of aminoglycoside gene aadA6. [ABSTRACT FROM AUTHOR]

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]

At tidal junctions, flow, sediment, and, indirectly, flooding risk are distributed over the downstream river branches. To characterize the hydrodynamic pattern related to the transport and distribution of suspended sediment, an intra-tidal field measurement was conducted at the first order tidal junction in the Pearl River Network, Makou-Sanshui (MK-SS), which was the first order junction and the apex of the delta. Two 13h boat-mounted ADCP surveys were implemented and 468 water samples were taken synchronously across three cross sections at wet and dry seasons during the spring tide. Observed spatiotemporal velocities were applied to elucidate the intra-tidal flow pattern in the tidal junction, and the acoustical backscatter intensity collected by ADCP was the inverse of the cross-sectional suspended sediment concentration (SSC). Additionally, vertical profiles of velocity and SSC allowed us to fit the lateral distribution of shear velocity and Rouse number, respectively. From these, we obtained the spatiotemporal variations of settling velocity, which then made it possible to interpret the time lag between flow and suspended sediment. Intra-tidal substance exchange, including flow flux produced by tidal wave and net suspended sediment, was inferred by Stokes transport, integrating axial velocities and the SSC. As a consequence of tidal impact, the flow processes of MK and SS were out of phase by 1–1.5 h. As the connecting channel of MK and SS, Ganggen (GG) experienced more frequent substance exchange, displaying a significant difference in flow pattern. A substantial clockwise secondary flow field was detected during the intra-tidal survey at GG, which was affected by the curved channel. This phenomenon was related to the cross-sectional distribution of SSC. Furthermore, the intra-tidal transport of suspended sediment exhibited an inverse direction during the wet and dry seasons. Sediment during the dry season favoured delivery from MK to SS, while it displayed an opposite trend during the wet season. The results reveal the pattern of intra-tidal partitioning of flow and sediment at tidal junctions. [ABSTRACT FROM AUTHOR]

Highlights • A symmetrical tide can be a balance between shallow water tides and asymmetry inherent in astronomical tides. • The preloading of tidal asymmetry in astronomical tides tends to be ebb dominant in diurnal or mixed tidal regimes. • River discharge attenuates tidal asymmetry significantly in upstream part of the tidal system. Abstract Tidal asymmetry in deltas is caused by both the intrinsic asymmetry, resulting from the combination of astronomical tides, and by nonlinear tidal interactions that occur in shallow water. The relative importance of these sources of tidal asymmetry in delta channel networks have remained poorly studied, partly due to the limitations of classical harmonic analysis (HA) in hindcasting nonstationary tides. The Pearl River Delta (PRD) is a multichannel system with rapidly changing bathymetry, subject to severe human interventions. This work applies a nonstationary harmonic model (NS_TIDE) to hydrological data from 15 stations in the PRD spanning the period 1961–2012. The spatiotemporal variation of multiple sources of tidal asymmetry is quantified by a skewness metric, revealing how similar or dissimilar the development of alternative sources of tidal asymmetry develop in the delta subject to study. A relative sensitivity coefficient (RSC) is introduced to decompose the contribution of tidal amplitude variations to multiple tidal asymmetries. Analytical results show the development of tides becoming gradually more asymmetric as they propagate into delta channel networks, and how this depends on the river flow. Variation in the orientation of tidal asymmetries induced by different combinations of tidal constituents leads to a complex pattern of the overall tidal asymmetry in the PRD. Our results show that tidal asymmetry in deltas can be significantly dependent on the river flow. [ABSTRACT FROM AUTHOR]

Based on the annual maximum water level record spanning about 60 years at 34 gauging stations, we conduct flood frequency analysis in the Pearl River Delta (PRD) with generalized extreme value (GEV) distribution. The GEV model performs sound estimation with the correlation coefficient at most stations larger than 0.99. To better understand the flood risk especially in ungauged regions, the spatial distribution of flood-stage is displayed for three given return periods, 10-year, 20-year and 50-year. Similar pattern can be identified for different return periods except the difference in magnitude, which generally exhibits a decreasing trend from the upper region to offshore area with a scope of about 2–9 m. Additionally, a comparison between pre-1980 and post-1980 is carried out to quantify the flood-stage alteration. The results show that most stations display increasing flood risk except for some stations in the upper estuaries, which experienced slight water level decline. Particularly, the lower part of the PRD is vulnerable to the most severe flood-stage increment. The estimated extreme water level increases by 0.35 m (14.96%), 0.59 m (21.23%) and 1.06 m (29.96%) on average at stations corresponding to 10-year, 20-year and 50-year return period, respectively. [ABSTRACT FROM AUTHOR]

• The developed MLNs counting model demonstrated acceptable ability in NPC. • LNNs counted by AMLNC showed favorable discriminatory in predicting prognostic. • AMLNC may serve as a reference tool for younger radiologists to evaluate MLNs. The number of metastatic lymph nodes (MLNs) is crucial for the survival of nasopharyngeal carcinoma (NPC), but manual counting is laborious. This study aims to explore the feasibility and prognostic value of automatic MLNs segmentation and counting. We retrospectively enrolled 980 newly diagnosed patients in the primary cohort and 224 patients from two external cohorts. We utilized the nnUnet model for automatic MLNs segmentation on multimodal magnetic resonance imaging. MLNs counting methods, including manual delineation-assisted counting (MDAC) and fully automatic lymph node counting system (AMLNC), were compared with manual evaluation (Gold standard). In the internal validation group, the MLNs segmentation results showed acceptable agreement with manual delineation, with a mean Dice coefficient of 0.771. The consistency among three counting methods was as follows 0.778 (Gold vs. AMLNC), 0.638 (Gold vs. MDAC), and 0.739 (AMLNC vs. MDAC). MLNs numbers were categorized into three-category variable (1–4, 5–9, > 9) and two-category variable (<4, ≥ 4) based on the gold standard and AMLNC. These categorical variables demonstrated acceptable discriminating abilities for 5-year overall survival (OS), progression-free, and distant metastasis-free survival. Compared with base prediction model, the model incorporating two-category AMLNC-counting numbers showed improved C-indexes for 5-year OS prediction (0.658 vs. 0.675, P = 0.045). All results have been successfully validated in the external cohort. The AMLNC system offers a time- and labor-saving approach for fully automatic MLNs segmentation and counting in NPC. MLNs counting using AMLNC demonstrated non-inferior performance in survival discrimination compared to manual detection. [ABSTRACT FROM AUTHOR]

Objective: This research was to investigate the role of goserelin in combination with endocrine therapy for the treatment of advanced breast cancer in premenopausal women positive for hormone receptors. Methods: We retrospectively analyzed 40 patients as the treatment group with advanced breast cancer who, were positive for hormone receptors, received goserelin in combination with endocrine therapy and 40 patients as the control group received endocrine therapy alone, matched for age, gender, receptor status, and tumor stage. Results: The median period of follow-up was 38.9 months. The response status at 6 months, the overall clinical benefit rate was 87.5% and 70.0% in the treatment group and control group, respectively. The mean progression-free survival (PFS) in the treatment group and control group was 27.9 and 16.9 months, respectively. The 1-, 2-, and 3-year PFS rates were 87.5%, 66.2%, and 49.7%, respectively, in the treatment group and 59.2%, 38.8%, and 35.3%, respectively, in the control group ( p=0.076). The 1-, 2-, and 3-year overall survival (OS) rates were 100%, 87.2%, and 76.6%, respectively, in the treatment group and 90.0%, 74.2%, and 55.8%, respectively, in the control group ( p=0.048). For the treatment group with age <40 years, PFS ( p=0.036) and OS ( p=0.014) were significantly longer than the control group, but it was no effect on the prognosis with the patients aged ≥40 years. Continued use of goserelin after disease progress again in the median survival time was significantly longer than nonusers (28.2 months vs. 7.0 months), and there is the potential benefit of OS ( p=0.070). Conclusions: For premenopausal hormone receptor-positive advanced breast cancer, goserelin-combined endocrine therapy can be used for those <40 years, the standard endocrine treatment for patients, we recommend continued use of goserelin for patients with disease progress again. [ABSTRACT FROM AUTHOR]

[Display omitted] The quasi-Monte Carlo (QMC) method was enhanced to solve the population balance model (PBM) including aggregation and fragmentation processes for simulating the temporal evolutions of characteristic sizes and floc size distributions (FSDs) of cohesive sediments. Ideal cases with analytical solutions were firstly adopted to validate this QMC model to illustrate selected pure aggregation, pure fragmentation, and combined aggregation and fragmentation systems. Two available laboratory data sets, one with suspended kaolinite and the other with a mixture of kaolinite and montmorillonite, were further used to monitor the FSDs of cohesive sediments in controlled shear conditions. The model results show reasonable agreements with both analytical solutions and laboratory experiments. Moreover, different QMC schemes were tested and compared with the standard Monte Carlo scheme and a Latin Hypercube Sampling scheme to optimize the model performance. It shows that all QMC schemes perform better in both accuracy and time consumption than standard Monte Carlo scheme. In particular, compared with other schemes, the QMC scheme using Halton sequence requires the least particle numbers in the simulated system to reach reasonable accuracy. In the sensitivity tests, we also show that the fractal dimension and the fragmentation distribution function have large impacts on the predicted FSDs. This study indicates a great advance in employing QMC schemes to solve PBM for simulating the flocculation of cohesive sediments. [ABSTRACT FROM AUTHOR]

• Rulefit enables the utilization of logical associations behind structured MRI report for nasopharyngeal carcinoma in the forms of prognostic rules. • The Rules model using Rulefit achieved a better accuracy and generalizability than common models for the prediction of overall survival among advanced nasopharyngeal carcinoma, with the highest C-index of 0.711 in external testing cohort. • Significant survival benefit was achieved in high-risk group stratified by Rules model with additional induction chemotherapy treatment. Structured MRI report facilitate prognostic prediction for nasopharyngeal carcinoma (NPC). However, the intrinsic association among structured variables is not fully utilised. This study aimed to investigate the performance of a Rulefit-based model in feature integration behind structured MRI report and prognostic prediction in advanced NPC. We retrospectively enrolled 1207 patients diagnosed with non-metastatic advanced NPC from two centres, and divided into training (N = 544), internal testing (N = 367), and external testing (N = 296) cohorts. Machine learning algorithms including multivariate analysis, deep learning, Lasso, and Rulefit were used to establish corresponding prognostic models. The concordance indices (C- indices) of three clinical and six combined models with different algorithms for overall survival (OS) prediction were compared. Survival benefits of induction chemotherapy (IC) were calculated among risk groups stratified by different models. A website was established for individualised survival visualisation. Incorporating structured variables into Stage model significantly improved the prognostic prediction performance. Six prognostic rules with structured variables were identified by Rulefit. OS prediction of Rules model was comparable to Lasso model in internal testing cohort (C-index: 0.720 vs. 0.713, P = 0.100) and achieved the highest C-index of 0.711 in external testing cohort, indicating better generalisability. The Rules model stratified patients into risk groups with significant 5-year OS differences in each cohort, and revealed significant survival benefits from additional IC in high-risk group. The Rulefit-based Rules model, with the revelation of intrinsic associations behind structured variables, is promising in risk stratification and guiding individualised IC treatment for advanced NPC. [ABSTRACT FROM AUTHOR]

Middle deep borehole heat exchanger (DBHE) has become widely known as one of the main ways of geothermal energy development and utilization, and the use of middle DBHE system for heating buildings has received much attention. More accurate analytical models for a coaxial borehole heat exchanger (CBHE) have been built using the convolution theorem, however, a U-shaped deep borehole heat exchanger (U-DBHE) has not been reported. Therefore, in this paper, to obtain more accurate fluid temperature distribution, an analytical model of middle DBHE considering geological stratification phenomenon is developed by using convolution theorem. The relative error of the analytical model is verified within 5% by numerical simulation. At the same time, the interaction between the three factors was analyzed and studied by response surface method: mass flow, inlet temperature and geothermal gradient on heat extraction and heat loss rate. The results reveal that for thermal extraction, the significance levels of the three factors are from large to small: geothermal gradient > inlet temperature > mass flow, for heat loss rate, the two factors of flow rate and inlet temperature are significant, and the impact of geothermal gradient is not significant. In this engineering project, when the inlet water temperature is 10 °C, the flow rate is 26.65 kg/s and the geothermal gradient is 4.5 °C/hm, there is a maximum heat extraction of 2424.16 kW. [ABSTRACT FROM AUTHOR]

The spectrum of tidal and subtidal water level variations in river deltas responds to river discharge variation, ocean tides, and human activities of many kinds. It remains a contemporary challenge to identify the main sources of changes in tidal dynamics in deltas, because of nonlinear interactions between tides and the river discharge in a changing setting. Understanding the main forcing factors controlling the evolution of mean water levels and the associated amplitudes and phases of tidal constituents can help to understand the causes of floods and the occurrence of low flows hindering navigation. Here, a nonstationary harmonic analysis tool (NS_TIDE) is applied to hydrological data from 14 stations in the Pearl River Delta (PRD) spanning the period 1961–2012. The water levels and main tidal constituent properties are decomposed into contributions of external forcing by river discharges and ocean tides, providing insight into the nonstationary tidal-fluvial processes. Significant temporal trends in mean water levels and tidal properties are observed in the PRD. Results indicate that there is spatial variability in the response of mean water levels and tidal properties to river discharge variation in the delta. The abrupt changes in bathymetry in the delta due to intensive sand excavation are likely responsible for the observed spatial variations in tidal response, which reduce the flood-dominant tidal asymmetry in this area. • Response of tidal amplitudes and phases to trends in river discharge varies spatially in a delta channel network. • Increased ocean tides amplify tides in the seaward part of a delta and elevate the mean surface levels at upstream stations. • Channel deepening reduces flood dominance in delta channels. [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]

Highlights • The optimal filler/sand ratios of sand concrete using GGBS and FA fillers are 0.13 and 0.11 respectively. • The mechanical properties of sand concrete increase and then decrease with filler content increasing. • Sand concrete made with superfine waste sand presents an excellent abrasion resistance. • Sand concrete with the GGBS filler has higher amount of hydrate products and lower porosity than that with FA. Abstract In this paper, superfine waste sand generated in waterway regulation engineering was used as the main raw material to produce sand concrete. The effects of ground granulated blast-furnace slag (GGBS) and fly ash (FA) on the mechanical properties, abrasion resistance, and microstructure of sand concrete were measured and compared. The results show that the mechanical properties of sand concrete increase and then decrease with increasing filler content. The optimal filler/sand (F/S) ratios of sand concrete using GGBS and FA fillers are 0.13 and 0.11, respectively. With 300 kg/m3 of cement content, the incorporation of 200 kg/m3 and 150 kg/m3 of GGBS and FA filler, respectively, results in maximum compressive strengths of 36.1 MPa and 30.5 MPa, respectively, at 28 days, and the corresponding splitting tensile strengths are 3.03 MPa and 2.15 MPa, respectively. This optimum mix with weight losses of 6.58% and 8.01% for GGBS and FA fillers, respectively, presents an excellent abrasion resistance. Furthermore, the test results of scanning electron microscopy and mercury intrusion porosimeter indicate that sand concrete with the GGBS filler has higher amount of hydrate products and lower porosity than that with FA. These findings verify the potential usage of sand concrete made with superfine waste sand as a substitute for ordinary concrete in local hydraulic engineering. [ABSTRACT FROM AUTHOR]

Calcium–modified water hyacinth biochar (WHCBC–400 and WHCBC–600) was prepared using water hyacinth as raw material and calcium chloride as modifier at two pyrolysis temperatures of 400 °C and 600 °C. The effectiveness for removal of malathion, a typical organophosphorus pesticide from water were comparatively examined by the prepared adsorbents. The impacts of the pyrolysis temperature on performance of the biochar and adsorption behavior of malathion on the modified biochar were systematically studied by surface analysis, removal efficiency tests under different solution conditions, as well as data simulations. The adsorption mechanisms and reusability of the modified biochar were also investigated and experimented, respectively. The results indicated that the WHCBC–600 had a larger specific surface area and pore volume than the WHCBC–400, while WHCBC–400 had a greater polarity and hydrophilicity. Both of the two prepared biochars followed pseudo–second–order kinetics and their adsorption isotherms conformed to the Sips model. The maximum adsorption capacities of WHCBC–400 and WHCBC–600 were 128 mg/g and 32.7 mg/g, respectively. It was found that the adsorption of malathion by the biochars were dominated by chemisorption. Diffusion at the liquid film was the rate–limiting step in the adsorption process. The difference in the form of the calcium loadings, polarity of biochar, and the rate–limiting step of adsorption were important factors affecting the adsorption capacity of the biochar. In comparison, the specific surface area and pore volume of the prepared absorbents had less significant effects on the adsorption capacity. The main adsorption mechanism of the two modified biochars was surface complexation. In addition, the solution pH and coexisting material had little effect on the adsorption of malathion by WHCBC–400 and WHCBC–600. Both of the modified biochar had good regeneration performance. The study provided a new adsorbent for the removal of malathion from water. [Display omitted] • Low temperature biochar had greater polarity. • High temperature biochar had larger specific surface area and pore volume. • WHCBC–400 (128 mg/g) had higher adsorption capacity than WHCBC–600 (32.7 mg/g). • Polarity and liquid film diffusion were affecting the adsorption effect of biochar. • The main adsorption mechanism was surface complexation. [ABSTRACT FROM AUTHOR]

Flow division at bifurcations in the Yangtze Estuary has received ample attention, since it may control the pathways of terrestrial sediments over downstream river branches including the 12.5 m Deepwater Navigation channel. While some efforts have been made to interpret flow division at the bifurcations of the Yangtze Estuary, little attention has been paid to the role of tides. Flow division at estuarine bifurcations is made complicated by tides that propagate from the outlet of the tidal channels into the delta. To quantify the tidal influence on the distribution of river discharge, and more generally, to understand the mechanisms governing the subtidal flow division at the tidally affected bifurcation in the Yangtze River Delta, a two-dimensional hydrodynamic model is employed. In this model, the landward boundary is chosen beyond the tidal limit, where the tidal motion has faded out entirely. The seaward boundary is chosen such that the river discharge does not influence the water level. Subtidal discharges are decomposed using the method of factor separation, to distinguish between the effects of tides, river discharge and river-tide interactions on the subtidal flow division. Results indicate that tides modify the river discharge distribution over distributary channels in the Yangtze River Delta, particularly in the dry season. A significant difference in the subtidal flow division during spring tide and neap tide shows that the tidally averaged flow division over the distributaries in the delta greatly depends on tidal amplitude. By varying the river discharge at the landward boundary and amplitudes and phases of the principal tidal constituents at the seaward boundary of the established model, the sensitivities of the subtidal flow division to the river discharge and tidal amplitude variation were investigated in detail. Generally, the tidal impacts on the subtidal flow division are around 12% to 22%, with river discharge varying from 30,000 m 3 s -1 to 20,000 m 3 s -1 . This effect on the flow distribution can even overwhelm the effects induced by river discharge based on geometry only, when the flow discharge is lowest. Furthermore, the fortnightly tidal cycle plays an important role in enhancing the inequality of the subtidal flow division caused by the M 2 tidal component solely at the tidal bifurcation in the Yangtze River Delta during low flow. [ABSTRACT FROM AUTHOR]

• The effects of anionic, cationic and neutral organic matters on the aggregation of microplastics are investigated. • All of the organic matters show positive effects on the growth of biofilm-coated microplastic aggregates. • The two-class population balance model is used to track the small and large microplastic subgroups under turbulence. Biofilm-coated microplastics are omnipresent in aquatic environments, carrying different organic matter (OM) that in turn influences the flocculation and settling of microplastic aggregates. In this study, the effects of chitosan, guar gum, humic acid, and xanthan gum on the flocculation of anthropogenic microplastics are examined under controlled shear through the mixing chamber experiments. The results show that all of the selected OMs have positive effects on biofilm culturing and thus enhance the growth of microplastic flocs, with more evident promoting effects for cationic and neutral OMs (i.e., chitosan and guar gum) than anionic OMs (i.e., humic acid and xanthan). No critical shear rate is observed in the size vs. shear relationship based on our measurements. In addition, the quadrature-based two-class population balance model is employed to track the development of bimodal floc size distributions (FSDs) composed of small and large microplastic flocs. The model predictions show reasonable agreement with the observed FSDs. The largest error of settling flux from the two-class model is 7.8% in contrast with the reference value measured by the camera-based FSDs with 30 bins. This study highlights the role of different OMs on microplastic flocculation and indicates that a two-class model may be sufficient to describe microplastic transport processes in estuaries. [Display omitted] [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]

Abstract: Spatial variations in grain-size parameters contain information on sediment transport patterns. Therefore, in this study, 106 surficial sediment samples taken from the Pearl River Estuary (PRE), South China, were analyzed, to better understand the net sediment transport pattern in this region. The PRE is an area of fine-grained sediment and shows muddy patches with relatively coarse sediment in the north. The sorting coefficient of surficial sediment over the whole estuary is higher than 2, indicating a very poor sorting in this region. The relationship between the sand, silt and clay contents of the sediments was analyzed by a log-ratio analysis, and it was indicated that the selective deposition is a non-linear function of the sediment mixture composition. The net sediment transport pathways indicate four distinct characteristics of sediment transport over the PRE. The sediment is transported obviously southeastward in the upper part of the estuary due to the relatively stronger fluvial dynamics and northwestward in the lower part, due to the stronger tidal dynamics. However, in the central part of the PRE, the sediment transport vectors display a clockwise rotation trend and net deposition is taking place, as indicated by the convergence of the grain size trend. The trend vectors show that some of the sedimentary material is supplied from upper and lower parts of the estuary to this depocenter. This result is consistent with the residual current circulation pattern near Neilingding Island. The patterns of sediment transport reveal directions with the main areas of deposition and possible dispersal patterns in the PRE. [Copyright &y& Elsevier]

Abstract: This paper focuses on identifying changes in the tidal range and the duration of the flood tide in the Pearl River Delta region, China. Mann–Kendall test and regression methods are employed to verify the existence of trends in the annual tidal range and duration series (from the 1950s to 2005) at 17 stations in the 3 major tributaries of the delta. The research results indicate that generally there is an increasing trend in the tidal range and flood tide duration at most of the stations in the channel network. Moreover, the more upstream the location of the station, the more obvious the change in trend is, and these increasing trends are all significant at the stations in the upper part of the delta. Specifically, the tidal range at Shilong station in the East River has increased abruptly since the middle of the 1980s such that the mean level of post-1990 data is approximately three times that for pre-1985. Most stations near the mouth of the estuary show significant downward trends in the tidal range and flood tide duration. Results of the intersection point of the Mann–Kendall test curves for these Pearl River Delta stations appear mostly in 1980s–1990s, indicating that a noticeable change point occurs during this period. Human activities in the Pearl River Delta reached their peak during the 1980s. Among these, large-scale and long-term sand excavation modified the hydrodynamic regime dramatically in a way that increased the water depth and lowered the level of the riverbed, leading to an increased tidal prism and upstream movement of the tidal limit. Land reclamation is also likely to have had a relatively large effect on the tidal range and flood tide duration at stations near to the estuary mouth. Changes in other factors, such as freshwater flow and sea-level rise, seem to be of relatively minor importance. It is noteworthy that in a dry season the tidal dynamics are greatly enhanced and has resulted in strong saltwater intrusion into the estuary in recent years. [Copyright &y& Elsevier]