Insights for booster chlorination strategy based on DBPs control in a large-scale water supply system.

Based on a one-year field investigation of disinfection by-products (DBPs) in large scale water distribution system (LSWDS), the various characteristics of DBPs together with their correlation with booster chlorination were elaborated through ArcGIS model. Furthermore, the effects of booster chlorination on DBP formation were investigated through simulated experiments. Residual chlorine showed a strong relationship with occurrence of different DBPs in LSWDS, and the yield of DBPs increased significantly after booster chlorination. The simulated chlorination experiments showed that diminution of the ratio of primary to secondary (booster) chlorination dosage, and delaying the secondary chlorine addition reduced the generation of DBPs during water conveyance. The yield concentrations of THMs and HAAs obviously increased after booster chlorination. The correlation between HAAs and chlorine dosage is weaker in the field research than in the simulation experiment while THMs had a positive correlation with the chlorine addition in both field research and simulation experiment.

Degradation of bisphenol A by UV/persulfate process in the presence of bromide: Role of reactive bromine.

Bromide (Br-), a ubiquitous species in natural water, is capable of reacting with sulfate radical (SO4∙-) and hydroxyl radical (∙OH) to form secondary reactive bromine species (RBS). The reaction routes can influence the degradation mechanisms and performance of these radicals for removal of target pollutants and may also form harmful bromine-containing disinfection by-products (Br-DBPs) during subsequent chlorination. In the present research, the UV-activated persulfate (PS) degradation of bisphenol A (BPA) was systematically examined in the presence of Br-. Results indicated that the presence of Br-enhanced the BPA degradation and both UV/PS and UV/PS/Br- processes followed the pseudo-first-order kinetics. At 0-0.8 mM Br-, 0.2 mM Br- exerted the best enhanced effect on BPA degradation, while RBS functioned as the major contributor in the presence of 0.05-0.5 mM Br-. Solution pH (6.0-8.0) barely affected the BPA degradation in the UV/PS system, but the introduction of Br- augmented the pH dependence. In the UV/PS/Br-system, the reaction rate constant of BPA increased/decreased with increasing PS/HA dosage, and was affected slightly in the presence of bicarbonate and chloride. According to the quantum chemical calculation, the second-order rate constants of BPA with ∙OH, SO4∙-, Br∙ and Br2∙- were calculated as 7.65 × 1010, 1.67 × 109, 1.77 × 108 and 2.83 × 102 M-1 s-1, respectively. Additionally, three degradation pathways of BPA were proposed based on DFT calculation and HPLC/MS analysis, and the formed bromine-containing products exhibited higher toxicity than BPA. Br-DBPs, particularly tribromomethane and tribromoacetic acid, generated from UV/PS/Br-pre-oxidation during BPA chlorination significantly increased the toxicity of total DBPs.

Computed Tomography and Magnetic Resonance Imaging in the Diagnosis of Primary Neuroendocrine Tumors of the Liver.

We selected 992 patients who presented to our hospital for treatment and were diagnosed with a neuroendocrine tumor (NET) between January 1, 2008, and December 31, 2018, of whom 17 were diagnosed with primary hepatic neuroendocrine neoplasm. The clinical data were analyzed to study the clinical value of computed tomography (CT) and magnetic resonance imaging data in the diagnosis of the disease. Nine tumors (52.9%) were in the right lobe of the liver, and 9 tumors (52.9%) were single. On imaging, the arterial phase, venous phase, and delayed phase continued to be slightly enhanced, showing low-density change relative to the liver and no portal tumor thrombus formation. Four patients (23.5%) had distant metastases, including adrenal glands, portal interstitial lymph nodes, retroperitoneal lymph nodes, and the gallbladder and peritoneum. In terms of pathological grade, there were 3 cases of NET G2, 2 cases of NET G3, 10 cases of neuroendocrine carcinoma (NEC; including 2 cases of large-cell NEC and 3 cases of small-cell NEC), and 2 cases of hepatocellular carcinoma and small-cell NEC. Seven patients were treated with surgery alone, 4 patients were treated with transcatheter arterial chemoembolization (TACE), and 2 patients were treated with other therapies. Three patients were not treated with surgery and were treated with TACE, etoposide and cisplatin, and octreotide acetate. One patient was discharged automatically. The tumor density on CT images was lower than that of the liver parenchyma; medium-high enhancement was seen in the arterial enhancement phase, and continuous enhancement was seen in the venous phase, but the degree of enhancement was reduced, and rarely with portal tumor thrombosis. Currently, surgery is the main treatment method; however, postoperative combined TACE is superior to surgery in combination with microwave ablation, chemotherapy, and other treatments.

[Cost-effectiveness of three-stage newborns hearing screening in Beijing].

OBJECTIVE: To evaluate the cost-effectiveness of two-stage and three-stage hearing screenings for newborns. METHODS: Hearing screening was performed for the normal newborns born in 7 hospitals in Beijing from October 2010 to December 2012 by using two stage and three stage strategies as well as hearing diagnostic test, and the cost effectiveness evaluation of two strategies was conducted. The data about the cost of screening and diagnostic test were from the hospitals. The data about car fare and charge for loss of working time of parents were collected through questionnaire survey. The sensitivity was analyzed according to the compliance rate. RESULTS: A total of 62,695 newborns received initial hearing screening, 5,809 newborns failed, the positive rate was 9.30%. A total of 4,933 newborns received rescreening, 972 newborns failed, the positive rate was 19.70%. Among the newborns failed in rescreening, 412 were provided with hearing diagnostic test and 360 received diagnostic test. The diagnostic test indicated that the hearing of 217 newborns were abnormal (60.28%). A total of 276 newborns received the third screening, 163 newborns failed, in which 125 received diagnostic test and 112 had abnormal hearing (45 had moderate and above hearing impairment), the abnormal rate was 89.60%. The average cost for three-stage screening (37,242 yuan RMB per case) was higher than that for two-stage screening (19,985 yuan RMB per case). With the increase of compliance, the cost-effectiveness of three-stage screening increased. CONCLUSION: The cost-effectiveness of three-stage screening was influenced by screening compliance. It is recommended that three-stage screening strategy might be taken in area where the screening compliance rate is >90%.

Contrast-enhanced multiphasic CT and MRI findings of adenosquamous carcinoma of the pancreas.

OBJECTIVE: The objective was to retrospectively study computed tomography (CT) and magnetic resonance imaging (MRI) findings of adenosquamous carcinoma of the pancreas (PASC). MATERIALS AND METHODS: Twelve patients (six women and six men; mean age, 61.3 years; range, 47-78 years) who presented with PASC as documented by pathologic examination underwent CT (n=10) or both CT and MRI (n=2) examination. Two radiologists evaluated the images and determined the location, size, margin, internal attenuation or signal intensity, contrast enhancement, and pattern for each tumor. Additionally, the presence of poorly enhanced areas, upstream main pancreatic duct (MPD) dilatation, pancreatic atrophy, and peripancreatic tissue metastasis were evaluated. Images were cross-referenced to surgical and pathologic findings. RESULTS: Masses were distributed throughout the pancreas (head, n=6; body, n=1; and tail, n=5). The tumor size ranged from 2.4 to 5.5 cm with an average size of 3.7 cm. Eight (66.7%) masses were ill defined, and seven (58.3%) were partially exophytic. Twelve (100%) masses showed heterogeneous and poorly enhanced areas. The lesions showed weak (n=5), moderate (n=5), or intense (n=2) progressive enhancement. The diameter of MPD in six patients ranged from 3.0 to 5.0 mm with an average of 3.7 mm. Pancreatic atrophy was not found. In 10 patients (83.3%), masses invaded the peripancreatic tissues. Two patients had metastatic liver disease at presentation. CONCLUSION: PASC typically presented as an ill-defined, hypovascular mass with a poorly enhanced area, exophytic tendency, and peripancreatic tissue invasion. Lack of pancreatic atrophy and mild MPD dilatation were also distinct from common duct pancreatic adenocarcinoma.