Performance and degradation pathway of florfenicol antibiotic by nitrogen-doped biochar supported zero-valent iron and zero-valent copper: A combined experimental and DFT study.

Fluorinated compounds are a class of organic substances resistant to degradation. Although zero-valent iron (Fe0) has a promising reducing capability, it still fails to degrade fluorine-containing antibiotics (i.e., florfenicol) efficiently. In this study, we applied a simple one-pot pyrolytic approach to synthesize nitrogen-doped biochar supported Fe0 and zero-valent copper (Cu0) composite (Fe/Cu@NBC) and investigated its performance on florfenicol removal. The results clearly showed that approximately 91.4% of florfenicol in the deionized water was removed by Fe/Cu@NBC within 8 h. As the reaction time was extended to 15 d, the total degradation rate of florfenicol reached 96.6%, in which the defluorination and dechlorination rates were 73.2% and 82.1%, respectively. Both experimental results and density functional theory calculation suggested that ∙OH and ·O2- triggered ß-fluorine elimination, resulting in defluorination prior to dechlorination. This new finding was distinct from previous viewpoints that defluorination was more difficult to occur than dechlorination. Fe/Cu@NBC also had a favorable performance for removal of florfenicol in surface water. This study provides a new insight into the degradation mechanism and pathway of florfenicol removal in the Fe/Cu@NBC system, which can be a promising alternative for remediation of fluorinated organic compounds in the environment.

Influences of offshore background wind on the formation of sea-land breeze and the characteristics of pollutant diffusion.

The formation of sea-land breeze (SLB) is primarily affected by background wind and temperature difference between the sea and nearby land. Because the intensity of sea breeze is significantly stronger than that of land breeze, land breeze may result in more accumulated pollutants under the condition of offshore background wind (OBW) than under the condition of no OBW in coastal areas. The formation process of sea-land breeze and the dispersion trajectory and accumulation effect of pollutants are studied under different velocities of OBW with the same sea-land temperature difference by employing computational fluid dynamics (CFD). The results reveal that the depth and the duration of sea breeze decrease with the increase of the velocity of OBW. The most unfavorable velocity of OBW (0.2 m s-1) exists when the concentration affected by OBW is higher than that by no OBW in coastal areas. The pollutants close to the ground will be blown to the inland by sea breeze when the velocity of OBW is less than 1.0 m s-1. When the velocity of OBW is larger than 2.0 m s-1, the pollutants will not occur on the inland due to the influence of OBW.

The influence of dusts on radiation and temperature over the eastern Asia with a regional climate model.

In order to investigate the climate effects of dusts, a regional climate model (RegCM 4.6) with the dust scheme was used to simulate the direct radiative forcing and air temperature response at 2 m near surface of dusts over the eastern Asia. Two sets of experiments were conducted, one with and one without dust aerosols. The experiment covered the main dust occurrence months from March to May for 8 years (2011-2018), and the simulation results were evaluated against ground station, reanalysis and satellite data. The model captured the spatiotemporal distribution of dust AOD and mass loading over the eastern Asia. However, it tended to underestimate the dust AOD and mass loading over the downwind of the dust source region and the Taklimakan Desert, and overestimate them over the north Xinjiang. The direct net radiative forcing including shortwave and longwave was up to -20 W·m-2 at the surface and -10 W·m-2 at the TOA over the dust source region due to the dominant negative shortwave forcing. The only exception of positive forcing at the TOA was observed along the western boundaries of the Tibetan Plateau due to the semi-persistent ice and snow cover. The dusts tended to warm the atmosphere more than 18 W·m-2 and cool the surface locally up to -0.7 °C. Among the 5 sub-areas, the largest averaged regional direct radiative forcing induced by dusts appeared over the central Inner Mongolia in May with the value of -3.0 ± 2.1, -12.2 ± 4.1 and 9.2 ± 4.4 W·m-2 at the TOA, surface and in the atmosphere, respectively. The results indicated that the model simulation for dusts should be further improved and the dust effects should be included in the estimates of climate change over the eastern Asia.

Fetal giant right cervical cyst causing severe tracheal compression: A case report.

RATIONALE: Fetal giant cervical cyst (FGCC) is a rare congenital anomaly. Sometimes FGCC may extend into the mediastinum, and result in severe tracheal compression, which is a life-threatening event at birth. PATIENT CONCERNS: We present a rare case of FGCC, which extended from the right neck into the superior mediastinum, and resulted in severe tracheal compression. DIAGNOSES: An FGCC was observed by ultrasonography and magnetic resonance imaging (MRI) at 27+4 weeks' gestation (WG). Fetal MRI at 35+1 WG showed that the FGCC was 3.3 × 8.2 × 7.5 cm and extended from the right neck into the superior mediastinum. Severe tracheal compression was observed and the inside diameter of the narrowest section of tracheostenosis appeared thread-like and measured only 0.1 cm. INTERVENTIONS: Cervical cyst reduction was performed prenatally under ultrasound guidance to alleviate the tracheal compression and maximize the chance of fetal survival 2 days before birth. At 36+3 WG, cesarean section was performed, and a female neonate was immediately delivered and intubated (3.5-mm tube) by an experienced anesthesiologist. Neonatal intralesional sclerotherapy and cystic component aspiration as guided by digital subtraction angiography were performed under general anesthesia. Anesthesia was maintained only with sevoflurane 3% in 2 L/min oxygen. Extubation was performed soon after surgery. OUTCOME: The neonate recovered uneventfully and was discharged 2 days postoperatively. After 140 days of follow-up, the neonate had recovered completely. LESSONS: If an FGCC is suspected by abdominal ultrasound, a fetal MRI is recommended to assess the severity of tracheal compression before birth, if feasible. An anesthesiologist should assess the risk of intubation failure at birth according to those results. If fetal severe tracheal compression is detected and it may result in inability of intubation at birth, prenatal cervical cyst reduction under ultrasound guidance may be effective for alleviating tracheal compression at birth, if feasible. This could maximize the chance of fetal survival. Improvement of fetal short- and long-term outcomes is important.

Dexmedetomidine sedation combined with epidural anesthesia for laparoscopy in a patient with suspected tuberculosis: A case report.

RATIONALE: We herein present a case in which satisfactory analgesia and sedation were provided by the combination of epidural anesthesia with dexmedetomidine for exploratory laparoscopy in a patient who was highly suspected to have tuberculosis. This is an optimal anesthesia method to minimize the risk of nosocomial infection, especially in developing countries that lack sterilizers for anesthesia machines. PATIENT CONCERNS: A 45-year-old woman suspected to have active tuberculosis was scheduled to undergo laparoscopy for definitive diagnosis of a pelvic mass. DIAGNOSES: Tuberculosis was diagnosed by exploratory laparoscopy. INTERVENTIONS: The surgery was performed under general anesthesia to prevent pain and discomfort during the procedure. However, ventilation machine used by patients with tuberculosis may have a potential risk of nosocomial infection and need disinfection by a special sterilizer machine even when using a bacterial/viral filter-heat and moisture exchanger. Therefore, the surgery was performed under continuous epidural anesthesia combined with dexmedetomidine. OUTCOMES: The surgery was successfully completed, and pelvic tubercles were confirmed to be caseous necrotic tissue by pathologic examination. The patient began regular antituberculosis treatment after discharging from the gynecology department. LESSONS: We conclude that administration of dexmedetomidine combined with epidural anesthesia can provide comfortable sedation for short laparoscopic procedures in patients with suspected tuberculosis. This technique can minimize the risk of nosocomial infection.

[Analysis of Aerosol Optical Depth Variation Characteristics for 10 years in Urumqi Based on MODIS_C006].

Based on the MYD04_L2_C006 dataset gained from Moderate resolution imaging spectroradiometer MODIS Level 2 at 10 km resolution of NASA's EOS (Earth Observing System) from 2006 to 2015, the aerosol optical depths (AODs) for 10 years under the condition of mild above atmospheric pollution (including mild) were analyzed for Urumqi City. The results showed that the average AODs in Urumqi were unimodally distribution over the 10 years. From January to April, the AODs gradually increased. During a year, the annual peak of 0.37±0.19 was in April, and the lowest value of 0.22±0.20 was in October. Owing to the frequent occurrence of dust weather conditions in spring, the largest seasonal variation of AOD was in spring, as the air pollution in the entire area was very serious, followed by summer and winter, with the smallest in autumn. In addition, the urban area was the high AOD value area in Urumqi, as its air pollution was more severe than that in the suburbs. The average value of AOD during the 10 years was 0.293. The highest value of AOD was 0.33 in 2006, and the lowest value of 0.24 was in 2008, which declined to 23.3% of that in 2007. The annual change in AOD in Urumqi over the 10 years rose steadily. Compared with previous studies, the lowest and highest values were both higher to different degrees. Despite the deduction trend in 2015, air pollution in Urumqi was serious in the studied decade, and thus control of such needs to be strengthened.

Comparison of nalbuphine and sufentanil for colonoscopy: A randomized controlled trial.

OBJECTIVES: Nalbuphine is as effective as morphine as a perioperative analgesic but has not been compared directly with sufentanil in clinical trials. The aims of this study were to compare the efficacy and safety of nalbuphine with that of sufentanil in patients undergoing colonoscopy and to determine the optimal doses of nalbuphine in this indication. METHODS: Two hundred and forty consecutive eligible patients aged 18-65 years with an American Society of Anesthesiologists classification of I-II and scheduled for colonoscopy were randomly allocated to receive sufentanil 0.1 µg/kg (group S), nalbuphine 0.1 mg/kg (group N1), nalbuphine 0.15 mg/kg (group N2), or nalbuphine 0.2 mg/kg (group N3). Baseline vital signs were recorded before the procedure. The four groups were monitored for propofol sedation using the bispectral index, and pain relief was assessed using the Visual Analog Scale and the modified Behavioral Pain Scale for non-intubated patients. The incidences of respiratory depression during endoscopy, nausea, vomiting, drowsiness, and abdominal distention were recorded in the post anesthesia care unit and in the first and second 24-hour periods after colonoscopy. RESULTS: There was no significant difference in analgesia between the sufentanil group and the nalbuphine groups (p>0.05). Respiratory depression was significantly more common in group S than in groups N1 and N2 (p<0.05). The incidence of nausea was significantly higher in the nalbuphine groups than in the sufentanil group in the first 24 hours after colonoscopy (p<0.05). CONCLUSIONS: Nalbuphine can be considered as a reasonable alternative to sufentanil in patients undergoing colonoscopy. Doses in the range of 0.1-0.2 mg/kg are recommended. The decreased risks of respiratory depression and apnea make nalbuphine suitable for patients with respiratory problems.

Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons.

Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.

Vertical distribution of ambient aerosol extinctive properties during haze and haze-free periods based on the Micro-Pulse Lidar observation in Shanghai.

Ambient aerosols make a significant contribution to the environment and climate through their optical properties. In this study, the aerosol extinction coefficient and Aerosol optical depth (AOD) retrieved using the Fernald Method from the ground-based Micro-Pulse Lidar (MPL) were used to investigate the characteristics of aerosols during haze and haze-free periods in Shanghai. There were 216 haze days including 145 dry haze days, 39 damp haze days and 32days of both dry and damp haze in Shanghai from March 2009 to February 2010. During the haze periods, aerosols were concentrated mainly below 600m resulting in the most severe pollution layer in Shanghai. In contrast to the aerosol optical properties during haze-free periods, aerosol extinction coefficients and AOD were larger in the lower altitude (below 1km) during haze periods. The lowest 1km contributed 53-72% of the Aerosol optical depth (AOD) below 6km for the haze periods and <41% of that for the haze-free periods except summer. According to the analysis of influencing factors, although atmospheric convection was strong in summer which led to reduce the extinction, the highest occurrence of haze with relatively low aerosol extinction most of time was in summer, which resulted from the factors such as higher relative humidity, temperature and more solar radiation causing hygroscopic growth of particles and formation of secondary aerosols; in spring and autumn, there was less haze occurrences because the boundary layer was relatively higher, which allowed pollutants to diffuse more easily, but spring was the second most frequency season of haze due to frequent dust transport from the north; in winter high concentrations of particles and low boundary layer height were not beneficial to the diffusion of pollutants near the surface and caused haze occurrence rather high with high aerosol extinction.

[Analysis of characteristics of black carbon concentration in Shanghai from 2008 to 2012].

The variations of black carbon (BC) mass concentration in Shanghai are analyzed and discussed by using hourly averaged data monitored continuously at Shanghai Urban Environmental Meteorological Center from January 2008 to December 2012. The results show that the annual mean mass concentration of BC decreased from (4 045.3 +/- 3 375.4) ng x m(-3) in 2008 to (2 766.2 +/- 2 078.9) ng x m(-3) in 2012, and the annual changes are 2.3%, - 6.5%, -18.7% and -12.1%, respectively. The yearly averaged BC mass concentration in Shanghai is on the low side of middle-level compared with other mega-cities of China. According to the test data,the highest monthly averaged concentration of BC appeared in November and December,which were 5 426.6 ng x m(-3) and 5 365.3 ng x m(-3), respectively,and then in January, June and October, which were 4402.5, 3763.3 and 3412.7 ng x m(-3), respectively. The diurnal cycles of the BC mass concentration show that there are two obvious peaks during morning 07:00-10:00 and during evening 18:00-22:00 Beijing time (BT), and the first peak was higher than the second on weekdays, but opposite on weekends and holidays. The daily mean mass concentration of BC was 9% higher on weekdays than on weekends and holidays. In addition, an empirical equation is obtained for daily BC concentration estimation and prediction using all the effective test data during the 5-year observation period and employing the regression analysis.

Effects of geometric parameters and electric indexes on the performance of laboratory-scale electrostatic precipitators.

The performance of electrostatic precipitators (ESPs) is affected by factors such as the geometric configurations, the charge conditions and the fluid flow and the particulate flow characteristics. In this paper, a theoretical model is presented to study the particle transport in the collecting channel of a laboratory-scale single-stage multi-wire ESP. The employed model is validated by comparing its predictions with published experimental data and other theoretical prediction models. The particle size distribution is represented by a lognormal function, and the effects of the geometric parameters of ESPs on collection efficiency under different charge conditions are calculated and analyzed. The results confirm that the collection efficiency of ESPs can be enhanced by employing large-sized corona wire under the same average current density or corona power ratio, while the opposite rule is shown under the same electric field strength.

Influence of carbonation on the acid neutralization capacity of cements and cement-solidified/stabilized electroplating sludge.

Portland cement (PC) and blended cements containing pulverized fuel ash (PFA) or granulated blast-furnace slag (GGBS) were used to solidify/stabilize an electroplating sludge in this work. The acid neutralization capacity (ANC) of the hydrated pastes increased in the order of PC > PC/GGBS > PC/PFA. The GGBS or PFA replacement (80 wt%) reduced the ANC of the hydrated pastes by 30-50%. The ANC of the blended cement-solidified electroplating sludge (cement/sludge 1:2) was 20-30% higher than that of the hydrated blended cement pastes. Upon carbonation, there was little difference in the ANC of the three cement pastes, but the presence of electroplating sludge (cement/sludge 1:2) increased the ANC by 20%. Blended cements were more effective binders for immobilization of Ni, Cr and Cu, compared with PC, whereas Zn was encapsulated more effectively in the latter. Accelerated carbonation improved the immobilization of Cr, Cu and Zn, but not Ni. The geochemical code PHREEQC, with the edited database from EQ3/6 and HATCHES, was used to calculate the saturation index and solubility of likely heavy metal precipitates in cement-based solidification/stabilization systems. The release of heavy metals could be related to the disruption of cement matrices and the remarkable variation of solubility of heavy metal precipitates at different pH values.