Positive profile of natural small molecule organic matters on emerging antivirus pharmaceutical elimination in advance reduction process: A deep dive into the photosensitive mechanism of triplet excited state compounds.

Natural small molecular organic matter (NSOM), ubiquitous in natural waters and distinct from humic acid or fulvic acid, is a special type of dissolved organic matter (DOM) which is characterized as strong photosensitivity and simple molecular structure. However, little study had been directed on the role of NSOM in eliminating emerging contaminants in advanced reduction process (ARP). This study took three small molecular isomeric organic acids (p-hydroxybenzoic acid, pHBA; salicylic acid, SA; m-hydroxybenzoic acid, mHBA) as the representative substances of NSOM to explore these mechanisms on promoting Ribavirin (RBV, an anti COVID-19 medicine) degradation in ultraviolet activated sulfite (UV/Sulfite) process. The results demonstrated that the observed degradation rate constant of RBV (kobs-RBV) was 7.56 × 10-6 s-1 in UV/Sulfite process, indicating that hydrated electron (eaq-) from UV/Sulfite process could not effectively degrade RBV, while it increased by 178 and 38 times when pHBA and SA were introduced into UV/Sulfite process respectively, suggesting that pHBA and SA strongly promoted RBV degradation while mHBA had no promotion on RBV abatement in UV/Sulfite process. Transient absorption spectra and reactive intermediates scavenging experiment indicated that the triplet excited state pHBA and SA (3pHBA* and 3SA*) contributed to the degradation of RBV through non-radical process. Notably, eaq- played the role of key initiator in transforming pHBA and SA into their triplet states. The difference of kobs-RBV in UV/Sulfite/pHBA and UV/Sulfite/SA process was attributed to different generation pathways of 3pHBA* and 3SA* (high molar absorptivity at the wavelength of 254 nm and photosensitive cycle, respectively) and their second order rate constants towards RBV (kRBV-3pHBA* = 8.60 × 108 M-1 s-1 and kRBV-3SA* = 6.81 × 107 M-1 s-1). mHBA could not degrade RBV for its lack of intramolecular hydrogen bond and low molar absorptivity at 254 nm to abundantly transform into its triplet state. kobs-RBV increased as pH increased from 5.0 to 11.0 in UV/Sulfite/SA process, due to the high yield of eaq- in alkaline condition which promoted the generation of 3SA* and the stable of the absorbance of SA at 254 nm. By contrast, kobs-RBV underwent a process of first increasing and then decreasing in UV/Sulfite/pHBA process as the increase of pH, and its highest value achieved in a neutral condition. This lied in the exposure of eaq- increased as the increase of pH which promoted the generation of 3pHBA*, while the molar absorptivity of pHBA at 254 nm decreased as the increase of pH in an alkaline condition which inhibited the yield of 3pHBA*. The RBV degradation pathways and products toxicity assessment indicated that UV/Sulfite/pHBA had better detoxification performance on RBV than UV/Sulfite/SA process. This study disclosed a novel mechanism of emerging contaminants abatement through non-radical process in NSOM mediated ARP, and provide a wide insight into positive profile of DOM in water treatment process, instead of only taking DOM as a quencher of reactive intermediates.

Long-Travel 3-PRR Parallel Platform Based on Biomimetic Variable-Diameter Helical Flexible Hinges.

Technological advancements across various sectors are driving a growing demand for large-scale three-degree-of-freedom micro-nano positioning platforms, with substantial pressure to reduce footprints while enhancing motion range and accuracy. This study proposes a three-prismatic-revolute-revolute (3-PRR) parallel mechanism based on biomimetic variable-diameter helical flexible hinges. The resulting platform achieves high-precision planar motion along the X- and Y-axes, a centimeter-level translation range, and a rotational range of 35° around the Z-axis by integrating six variable-diameter flexible helical hinges that serve as rotational joints when actuated by three miniature linear servo drives. The drives are directly connected to the moving platform, thereby enhancing the compactness of the system. A kinematic model of the motion platform was established, and the accuracy and effectiveness of the forward and inverse kinematic solutions were validated using finite element analysis. Finally, a prototype of the 3-PRR parallel platform was fabricated, and its kinematic performance was experimentally verified visually for improved endpoint displacement detection. The assessment results revealed a maximum displacement error of 9.5% and confirmed that, judging by its favorable workspace-to-footprint ratio, the final system is significantly more compact than those reported in the literature.

Molecular characterization of Cryptosporidium spp. and Giardia duodenalis in pet cats in Henan Province, central China.

Cryptosporidium spp. and G. duodenalis often infect humans, cats, and other mammals, causing diarrhea and being responsible for numerous outbreaks of waterborne and foodborne infections worldwide. The rapid increase in the number of pet cats poses a substantial public health risk. However, there were few reports about the infection of Cryptosporidium spp. and G. duodenalis infections in pet cats in Henan Province, central China. Thus, to understand the prevalence and genetic distribution of Cryptosporidium spp. and G. duodenalis in pet cats, and to evaluate the zoonotic potential, possible transmission routes and public health implications of isolates, fecal samples (n = 898) were randomly collected from pet cats in 11 cities in Henan Province, central China. Nested PCR based on the SSU rRNA gene and bg gene was used to the prevalence of Cryptosporidium spp. and G. duodenalis, respectively. The prevalence was 0.8 % (7/898) and 2.0 % (18/898) for Cryptosporidium spp. and G. duodenalis respectively. Additionally, the Cryptosporidium spp. positive isolates were identified as C. parvum subtype IIdA19G1 by gp60 gene. In the present study, the IIdA19G1 subtype was discovered in pet cats for the first time in China, enriching the information on the host type and geographical distribution of Cryptosporidium spp. in China. For G. duodenalis, a total of 18 G. duodenalis positive samples were identified, belonging to four assemblages: a zoonotic assemblage A1 (4/898), three host-specific assemblages C (8/898), D (5/898), and F (1/898). Interestingly, we found that pet cats infected with Cryptosporidium spp. and G. duodenalis are more likely to experience emaciation symptoms compared to the negative group. More importantly, the prevalence of Cryptosporidium spp. and G. duodenalis detected in the present study were low, but the subtype IIdA19G1 of Cryptosporidium spp. and the assemblages A1, C, D, and F of G. duodenalis have the potential for zoonotic transmission. Thus, we should focus on preventing and controlling the risk of cross-species transmission that may occur in pet cats in Henan Province.

Adaptive metabolic response to short-term intensive fasting.

BACKGROUND & AIMS: Short-term intensive fasting (STIF), known as beego in Chinese phonetic articulation, has been practiced for more than two thousand years. However, the potential risk of STIF and the body's response to the risk have not been adequately evaluated. This study aims to address this issue, focusing on the STIF-triggered metabolic response of the liver and kidney. METHODS: The STIF procedure in the clinical trial includes a 7-day water-only intensive fasting phase and a 7-day gradual refeeding phase followed by a regular diet. The intensive fasting in humans was assisted with psychological induction. To gain insights not available in the clinical trial, we designed a STIF program for mice that resulted in similar phenotypes seen in humans. Plasma metabolic profiling and examination of gene expression as well as liver and kidney function were performed by omics, molecular, biochemical and flow cytometric analyses. A human cell line model was also used for mechanistic study. RESULTS: Clinically significant metabolites of fat and protein were found to accumulate during the fasting phase, but they were relieved after gradual refeeding. Metabolomics profiling revealed a universal pattern in the consumption of metabolic intermediates, in which pyruvate and succinate are the two key metabolites during STIF. In the STIF mouse model, the accumulation of metabolites was mostly counteracted by the upregulation of catabolic enzymes in the liver, which was validated in a human cell model. Kidney filtration function was partially affected by STIF but could be recovered by refeeding. STIF also reduced oxidative and inflammatory levels in the liver and kidney. Moreover, STIF improved lipid metabolism in mice with fatty liver without causing accumulation of metabolites after STIF. CONCLUSIONS: The accumulation of metabolites induced by STIF can be relieved by spontaneous upregulation of catabolic enzymes, suggesting an adaptive and protective metabolic response to STIF stress in the mammalian body.

The applied value in brain gray matter nuclei of patients with early-stage Parkinson's disease : a study based on multiple magnetic resonance imaging techniques.

PURPOSE: This study compares the observation efficiency of brain gray matter nuclei of patients with early-stage Parkinson's disease among various Magnetic Resonance Imaging techniques, which include susceptibility weighted imaging (SWI), quantitative susceptibility imaging (QSM), diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI). Based on the findings, this study suggests an efficient combination of scanning techniques for brain gray matter nuclei observation, aiming to provide an opportunity to advance the understanding of clinical diagnosis of early-stage Parkinson's disease. METHODS: Forty examinees, including twenty patients who were clinically diagnosed with early Parkinson's disease with a course of 0.5-6 years (PD group) and twenty healthy controls (HC group), underwent head MRI examination. Philips 3.0T (tesla) MR machine was used to measure the imaging indexes of gray matter nuclei in patients with early Parkinson's disease. SWI, QSM, DTI and DKI were used for diagnosis. SPSS (Statistical Product and Service Solutions) 21.0 was used for data analysis. RESULTS: When SWI was used, fifteen PD patients and six healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of nigrosome-1 on imaging were 75.0%, 30.0%, 51.7%, 54.5% and 52.5% respectively. By contrast, when QSM was used, 19 PD patients and 11 healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of Nigrosome-one on imaging were 95.0%, 55.0%, 67.9%, 91.7% and 75.0% respectively. The mean kurtosis (MK) value within both the substantia nigra and thalamus, together with the mean diffusivity (MD) within both the substantia nigra and the head of caudate nucleus in PD group was greater than that of HC group. The susceptibility values within the substantia nigra, red nucleus, head of caudate nucleus and putamen of PD group was greater than that of HC group. The MD value in substantia nigra reveals the optimal diagnostic efficiency to distinguish the HC group and the PD group, followed by the MK value in substantia nigra. Specifically, the maximum area under ROC curve (AUC) of the MD value was 0.823, the sensitivity 70.0%, the specificity 85.0%, and the diagnostic threshold 0.414. The area under ROC curve (AUC) of the MK value was 0.695, the sensitivity 95.0%, the specificity 50.0%, and the diagnostic threshold was 0.667. Both of them were statistically significant. CONCLUSIONS: In the early diagnosis of Parkinson's disease, QSM is more efficient than SWI in observing nigrosome-1 in substantia nigra. In the early diagnosis of Parkinson's disease, MD and MK values of substantia nigra in DKI parameters have higher diagnostic efficiency. The combined scanning of DKI and QSM has the highest diagnostic efficiency and provides imaging basis for clinical diagnosis of early Parkinson's disease.

The adsorption mechanism of sludge-based biochar toward highly concentrated organic membrane concentrates from landfill leachate.

In this study, the sludge-based biochar (BC) was prepared by dewatered sludge from a membrane bioreactor to treat the membrane concentrate. Then, the adsorbed and saturated BC was regenerated (RBC) by pyrolysis and deashing treatment to further treat the membrane concentrate. Afterward, the composition of membrane concentrate before and after BC or RBC treatment was detected, and the biochars' surface characteristics were characterized. The results showed that RBC outperformed BC in the abatement of chemical oxygen demand (CODCr), ammonia nitrogen (NH3-N), and total nitrogen (TN), with their removal rates of 60.07%, 51.55%, and 66.00%, respectively, an improvement of 9.49%, 9.00% and 16.50% of the removal rate compare to BC. The specific surface area of BC and RBC was about 109 times as much as the original dewatered sludge, and the pore size of BC and RBC belonged to mesopore which was a benefit for removing small and mediate size pollutants. The increase of the oxygen-containing functional group in RBC and the ash abatement contributed much to the improvement of RBC adsorption performance. In addition, cost analysis showed that BC+RBC had a cost of 0.76$/kg for COD removal, which was a lower cost than other common membrane concentrate treatment technologies.

Knowledge, attitude, and practices on COVID-19 prevention and diagnosis among medical workers in the radiology department: A multicenter cross-sectional study in China.

Objective: The aim of this study was to investigate the knowledge, attitude, and practice (KAP) of medical workers in the radiology department toward the prevention and diagnosis of COVID-19. Methods: This multicenter cross-sectional study was conducted among medical workers in the radiology department of 17 hospitals between March and June 2022. Results: A total of 324 medical workers were enrolled. The mean knowledge scores were 15.3 ± 3.4 (out of 23), attitude scores were 31.1 ± 5.6 (range 8-40), and practice scores were 35.1 ± 4.4 (range 8-40). Positive attitudes (OR = 1.235, 95% CI: 1.162-1.311, P < 0.001) and aged 41-50 years were independently associated with higher practice scores. Those with the better practice were more likely to be older (OR = 2.603, 95% CI: 1.242-5.452, P = 0.011), nurses (OR = 2.274, 95% CI: 1.210-4.272, P = 0.011) and with junior/intermediary/vice-senior title (OR = 2.326, 95% CI: 1.030-5.255, P = 0.042; OR = 2.847, 95% CI: 1.226-6.606, P = 0.015; OR = 4.547, 95% CI: 1.806-11.452, P = 0.001, respectively). Subgroup analysis revealed significant differences in knowledge between technicians and physicians and nurses and between staff working in tertiary hospitals and non-tertiary hospitals. Knowledge is positively correlated with attitude (ß = 0.54, P < 0.001), and attitude is positively correlated with practice (ß = 0.37, P < 0.001). Attitudes significantly mediated the association between knowledge and practice (ß = 0.119, P < 0.001). Conclusion: The radiology medical workers showed moderate knowledge but good attitudes and practices of prevention and diagnosis of COVID-19. Attitudes were found to be positively associated with better practices of prevention and diagnosis of COVID-19. Attitudes significantly mediated the association between knowledge and practice.

Role of trace TEMPO as electron shuttle in enhancing chloroquine phosphate elimination in UV-LED-driven persulfate activation process.

Chloroquine Phosphate (CP) is an antiviral drug used for treatment of COVID-19. It is released into wastewater and eventually contaminates natural water. This study reports an effective homogeneous catalysis way for CP degradation by the 2,2,6,6-Tetramethylpiperidine-N-oxyl (TEMPO) enhanced persulfate (PDS) activation under UVB-LEDs irradiation at 305 nm. TEMPO at a low concentration (0.1 µM) enhanced CP degradation in UV305/PDS process in deionized water at different pHs, in different anions and different molecular weight dissolved organic matter solutions and in real surface water. The enhancement was verified to be attributed to the electron shuttle role of TEMPO, which promoted the yield of SO4 •- by enhancing electron donating capacity of the reacting system. The degradation products of CP and their acute toxicities suggested that UV305/PDS/TEMPO process has better performance on CP detoxification than UV305/PDS process. This study provides a new way to tackle the challenge of pharmaceutical pollutions in homogeneous photocatalysis process for natural water and sewage restoration.

The role of trace N-Oxyl compounds as redox mediator in enhancing antiviral ribavirin elimination in UV/Chlorine process.

Ribavirin (RBV) is an antiviral drug used for treating COVID-19 infection. Its release into natural waters would threaten the health of aquatic ecosystem. This study reports an effective approach to degrade RBV by the trace N-oxyl compounds (2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and N-Hydroxyphthalimide (NHPI)) enhanced UV activated free chlorine (UV/Chlorine) process. The results indicated that TEMPO and NHPI at low concentrations (0.1 µM and 1 µM, respectively) could strongly enhance RBV degradation in both deionized water with different pHs and practical surface water. The enhancement was verified to be attributed to the transformation of TEMPO and NHPI into their reactive forms (i.e., TEMPO+ and PINO), which generations deeply relied on radicals. The two N-oxyl compounds inhibit ClO• yield by hindering the reaction of free chlorine vs. HO• and Cl•. The analyses on acute toxicities of RBV degradation products indicate that UV/Chlorine/N-oxyl compounds process can detoxify RBV more efficiently than UV/Chlorine process.

Behavior and mechanism of atrazine adsorption on pristine and aged microplastics in the aquatic environment: Kinetic and thermodynamic studies.

Microplastics (MPs) are emerging pollutants that have gained much attention due to their potential harm to aquatic ecosystems and organisms. In particular, MP conjugates are loaded with chemical contaminants (e.g., atrazine pesticide), which may be ingested by organisms and can pose higher risks. However, the combined pollution effects and interaction mechanisms remain poorly understood. In this study, we systematically explored the adsorption behaviors and mechanisms of atrazine (ATZ) on pristine and aged MPs using kinetics, isotherms, and thermodynamic models. The target MPs included polystyrene (PS), polyethylene (PE), and polypropylene (PP) as well as the corresponding aged types. Moreover, the effects of pH, humic acid (HA), ionic strength, and ion species (Cl-, SO42-, HCO3-, Mg2+, and Ca2+) of aqueous factors were evaluated. The adsorption capacities of MPs under kinetic equilibrium conditions were as follows: aged PE (0.940 mg g-1) > aged PP (0.677 mg g-1) > aged PS (0.663 mg g-1) > PS (0.565 mg g-1) > PE (0.535 mg g-1) > PP (0.410 mg g-1). The adsorption kinetics and isotherm model results suggested a combination of physisorption and chemisorption. The aging process and pH significantly affected the intrinsic charge on the surface of the MPs and their adsorption capacities. Moreover, the presence of water medium parameters might enhance or inhibit adsorption of different MPs. Hydrophobic and electrostatic attraction mainly contributed to the adsorption of ATZ on pristine MPs, whereas complex surface diffusion and hydrogen bonding dominated the ATZ adsorption on aged MPs with more oxygen-containing groups. In addition, we examined the desorption performance of ATZ from MPs under simulated gastric and intestinal conditions of warm-blooded animals, and found that the ATZ desorption ratio of aged PE (35.3%) showed the most significant effects among the six target types of MPs. This study provides in-depth insights into the co-existence and complex behaviors of MPs and the pesticide pollutant ATZ, to attract further attention to their ecological risks in freshwater environments.

Free carrier induced dark pulse generation in microresonators.

We theoretically demonstrate a novel, to the best of our knowledge, mechanism for dark pulse excitation in normal dispersion microresonators exploiting free carrier dispersion and free carrier absorption effects due to multi-photon absorption. Dark pulses can be generated in the three- and four-photon absorption regimes in the presence or absence of external reverse bias to control the lifetime of free carriers, respectively. Direct generation of dark pulses is proven to be feasible in both regimes with a frequency fixed laser. The dynamics of their temporal and spectral evolution have also been investigated. Our findings establish a reliable path for dark pulse and Kerr microcomb generation in related platforms with simplified controlling and tuning techniques.

Effects of fulvic acid size on microcystin-LR photodegradation and detoxification in the chlorine/UV process.

Microcystin-LR (MC-LR), a polypeptide toxin generated by cyanobacteria, threatens the safety of drinking water supplies. In this study, fulvic acid (FA) was separated into two molecular weight (MW) ranges to evaluate the effects of FA size on MC-LR degradation in the chlorine/UV process. The rates of MC-LR degradation were significantly reduced in FA-containing water (3.7 × 10-3 s-1 for small MW FA; 4.3 × 10-3 s-1 for large MW FA) as compared with FA free water (4.9 × 10-3 s-1). The contributions of ClO• to MC-LR degradation were dramatically lower in small MW FA water (0.4%) than large MW FA (13.9%) and FA free water (17.4%), suggesting inhibition by lignin-like substances in FA in the transformation of Cl• to ClO• and scavenging ClO•. Monochlorination and hydroxylation occurred in the first step of the MC-LR degradation process. The accumulation of intermediate products in the chlorine/UV process indicated that small MW FA inhibited further degradation of MC-LR. Small MW FA, rather than MC-LR degradation, was the dominant factor in minimizing MC-LR cytotoxicity toward a human intestinal epithelial cell line.

Comprehensive evaluation and prediction of tourism ecological security in droughty area national parks-a case study of Qilian Mountain of Zhangye section, China.

Tourism activities have brought overexploitation of natural ecotourism resources and ecological pressure challenge though it exactly contributes to the economic prosperity of a region. Research on tourism ecological safety is of great importance for tourist destinations to balance the relationship between environmental protection and tourism development. Qilian Mountains National Park (QMNP) has a prominent ecological status and is a vital ecological barrier in the northwest of China, which attracts large numbers of tourists every year for its rich tourism resources in the Zhangye (ZY) region. However, there is still a lack of systematic research on the environmental impact of tourism activities and on achieving sustainable development of ecotourism in national parks. We took QMNP-ZY as the study object, establishing the system of indicators based on the PSR model for the comprehensive evaluation of tourism ecological safety and the diagnosis of the main obstacles. Moreover, the autoregressive integrated moving average (ARIMA) model was introduced to forecast the evolutionary trends of tourism ecological security in QMNP-ZY. The results showed that (1) The tourism ecological security composite values of the QMNP-ZY exhibited a "U"-type evolution of "first fall-then rise" feature, and the pressure layer gradually became the dominant factor. (2) For the main barrier factors, there had been a shift from response factors. (3)The output of the ARIMA model demonstrated that the level of tourism ecological security would rise in a short period and then decline a few years later. Especially, the contribution degree of economic to the tourism eco-security development will weaken with the region's economy growing.

Ultraviolet photosensitized transformation mechanism of microcystin-LR by natural organic matter in raw water.

Microcystins (MCs), produced by cyanobacterial blooms in eutrophic water, are common toxic metabolites and a potential threat to human health. However, the mechanism of MC photodegradation by photosensitizers in raw water remains unclear. In photodegradation and quenching experiments, this study investigates the photosensitized degradation of microcystin-LR (MC-LR) by fulvic acid (FA, a kind of dissolved organic matter with natural photosensitizing properties) under ultraviolet (UV) light irradiation. The photodegradation mechanisms of FA are also explored. The photodegradation process of MC-LR by FA was consistent with second-order reaction kinetics. The degradation rate of MC-LR in FA decreased from 80% to 55% as the pH increased from 3 to 9, because the binding ability of FA to MC-LR reduces as the pH increases. Given that FA can both inhibit and promote MC-LR degradation depending on its concentration, the optimum initial FA concentration for degrading MC-LR was determined as 9.86 mgC·L-1. The excited triplet state of FA (3FA∗) accounted for 50.12% of the MC-LR loss; the remaining loss (49.88%) was contributed by reactive oxygen species and direct photolysis. This implies that the main pathway of MC-LR degradation is reaction with 3FA∗. The MC-LR degradation rate is 36% higher under UV irradiation than that under simulated sunlight irradiation.

Anaerobic dynamic membrane bioreactor (AnDMBR) for wastewater treatment: A review.

Recently, an increasing level of attention has focused on the emerging technology of anaerobic dynamic membrane bioreactors (AnDMBRs), owing to its merits such as low membrane module cost, easy control of membrane fouling, low energy consumption and sludge production, as well as biogas production. As research on AnDMBRs is still in the nascent stage, an introduction of bioreactor configurations, dynamic membrane (DM) module, and DM layer formation and cleaning is firstly presented. The process performance of the AnDMBR for wastewater treatment is then reviewed with regard to pollutant removal, DM filterability, biogas production, and potential advantages over the conventional anaerobic membrane bioreactor (AnMBR). In addition, the important parameters affecting process performance are briefly discussed. Lastly, the challenges encountered and perspectives regarding the future development of the AnDMBR process to promote its practical applications are presented.

Automatic seed picking for brachytherapy postimplant validation with 3D CT images.

PURPOSE: Postimplant validation is an indispensable part in the brachytherapy technique. It provides the necessary feedback to ensure the quality of operation. The ability to pick implanted seed relates directly to the accuracy of validation. To address it, an automatic approach is proposed for picking implanted brachytherapy seeds in 3D CT images. METHODS: In order to pick seed configuration (location and orientation) efficiently, the approach starts with the segmentation of seed from CT images using a thresholding filter which based on gray-level histogram. Through the process of filtering and denoising, the touching seed and single seed are classified. The true novelty of this approach is found in the application of the canny edge detection and improved concave points matching algorithm to separate touching seeds. Through the computation of image moments, the seed configuration can be determined efficiently. Finally, two different experiments are designed to verify the performance of the proposed approach: (1) physical phantom with 60 model seeds, and (2) patient data with 16 cases. RESULTS: Through assessment of validated results by a medical physicist, the proposed method exhibited promising results. Experiment on phantom demonstrates that the error of seed location and orientation is within ([Formula: see text]) mm and ([Formula: see text])[Formula: see text], respectively. In addition, the most seed location and orientation error is controlled within 0.8 mm and 3.5[Formula: see text] in all cases, respectively. The average process time of seed picking is 8.7 s per 100 seeds. CONCLUSIONS: In this paper, an automatic, efficient and robust approach, performed on CT images, is proposed to determine the implanted seed location as well as orientation in a 3D workspace. Through the experiments with phantom and patient data, this approach also successfully exhibits good performance.

The contribution of component variation and phytoplankton growth to the distribution variation of chromophoric dissolved organic matter content in a mid-latitude subtropical drinking water source reservoir for two different seasons.

The distribution variation in chromophoric dissolved organic matter (CDOM) content in mid-latitude subtropical drinking water source reservoirs (MDWSRs) has great significance in the security of aquatic environments and human health. CDOM distribution is heavily influenced by biogeochemical processes and anthropogenic activity. However, little is known regarding the impact of component variation and phytoplankton growth on CDOM distribution variation in MDWSR. Therefore, samples were collected from a representative MDWSR (the Shanzai Reservoir) for analysis. CDOM absorption and fluorescence coupling with parallel factor analysis were measured and calculated. The results indicated that only two CDOM components were found in the surface water of Shanzai Reservoir, fulvic acid, and high-excitation tryptophan, originating from terrestrial and autochthonous sources, respectively. The types of components did not change with the season. The average molecular weight of CDOM increased in proportion to its fulvic acid content. The distribution variation in CDOM content mainly resulted from the variation in two CDOM components in summer and from high-excitation tryptophan in winter. Phytoplankton growth strongly influenced the distribution variation of CDOM content in summer; the metabolic processes of Cyanobacteria and Bacillariophyta consumed fulvic acid, while that of Cryptophyta produced high-excitation tryptophan.

Effect of a dam on the optical properties of different-sized fractions of dissolved organic matter in a mid-subtropical drinking water source reservoir.

The presence of a dam on a river is believed to have a key role in affecting changes in the components of the chromophoric dissolved organic matter (CDOM) in reservoirs. However, questions remain about the mechanisms that control these changes. In this study, we used tangential ultrafiltration, fluorescence spectrum and phytoplankton cell density detection to explore the impacts of a dam on the CDOM components in the Shanzai Reservoir, a source of drinking water. The results demonstrated each CDOM size fraction comprised two main components, namely C1 (protein-like substance) and C2 (humic-like substance). The C1 content had a higher value in areas with slow flow than in the normal river channel, while the C2 contents were generally stable in the flow direction. The topography of the reservoir site affected the structure of the CDOM components based on changes in the hydraulic conditions caused by the dam. The variations in the CDOM components, hydraulic parameters and fluorescence indices in the river flow direction indicated that the contribution of the phytoplankton to the CDOM content increased as the distance to the dam decreased, phytoplankton metabolism enhanced C1 content of the 1-10kDa molecular weights range fraction. Further, the contributions of different phytoplankton biomass to C1 proved that the dam changed the hydraulic conditions, had secondary effects on the metabolism of the phytoplankton, and resulted in changes in the structure of the CDOM components.

Spatiotemporal variability in salinity and hydraulic relationship with salt intrusion in the tidal reaches of the Minjiang River, Fujian Province, China.

Salinity is one of the most important factors for tidal-affected water bodies including estuaries and tidal river reaches. However, due to the limitations of simultaneous manual monitoring in long-distance areas, studies of estuaries are preferred to tidal reaches. Hence, in this study, we investigated the tidal reach of the Minjiang River and five sets of field observations were used to determine the influence of saltwater intrusion in different seasons. During the dry and wet season with low discharge, the longitudinal salinity profiles showed that a station located about 45 km from the river mouth still suffered from saltwater intrusion especially when the upstream discharge was under 754 m3 s-1, where the periodical fluctuation in the salinity remained the same with the water level, but there was a time lag of approximately 4 h compared with the discharge process. However, during the wet season in April and May 2016, the monitored salinity was approximately at the detectable limit of 0.02-0.04 ppt at the station close to the river mouth, which indicated that there was no saltwater exchange into the river, although dual flow directions were observed in the survey periods. The major differences among five survey periods were mainly related to upstream discharge rather than the seasons, the tidal range, and tidal excursion. The conclusions of this study have strategic importance for protecting water sources by guiding the government to assess the optimal freshwater release time and discharge rate to prevent saltwater entering the important tidal-affected river reaches.

Characterization of a hybrid powdered activated carbon-dynamic membrane bioreactor (PAC-DMBR) process with high flux by gravity flow: Operational performance and sludge properties.

Three PAC-DMBRs were developed for wastewater treatment under different PAC dosages with biomass concentrations averaged at 2.5, 3.5 and 5.0g/L. The DMBRs could be continuously operated at 40-100L/m2h, while higher fluxes were obtained within the PAC-DMBRs with hydraulic retention times varying in 4-10h. A dose of 1g/L PAC brought about obvious improvement in the sludge particle size distribution, settling, flocculating and dewatering properties due to the formation of biological PAC, and the sludge properties were further improved at a higher PAC dose (3g/L). The addition of PAC notably shortened the DM formation time after air backwashing and enhanced pollutant removal. Moreover, under a long solid retention time (approximately 150d), the concentrations of both soluble and bound extracellular polymeric substances (EPS) decreased substantially because of the adsorption and biodegradation effects of the biological PAC. No obvious impact on biomass activity was observed with PAC addition.