Fate of dissolved organic nitrogen during biological nutrient removal wastewater treatment processes.

Due to its potential to form toxic nitrogenous disinfection byproducts (N-DBPs), dissolved organic nitrogen (DON) is considered as one of the most important parameters in wastewater treatment plants (WWTP). This study describes a comprehensive investigation of variations in DON levels in orbal oxidation ditches. The results showed that DON increased gradually from 0.71 to 1.14 mg I(-1) along anaerobic zone, anoxic zone, aerobic zone 1 and aerobic 2. Molecular weight fractionation of DON in one anaerobic zone and one aerobic zone (aerobic zone 2) was performed. We found that the proportion of small molecular weight (<6 kDa) decreased and large molecular weight (> 20 kDa) showed opposite trend. This variation may have been caused due to the release of different types of soluble microbial products (SMPs) during biological processes. These SMPs contained both tryptophan protein-like and aromatic protein-like substances, which were confirmed by three-dimensional excitation-emission matrix (EEM) analysis.

Removal of algae from raw water by ultrasonic irradiation and flocculation: a pilot scale experiment.

Using Chl alpha removal rate as index, a 28 kHz/900w ultrasonic cleaning machine was applied to testify algal removal by ultrasonic irradiation from raw water of a pool, where Microcystis aeruginosa colonies is absolutely dominated with temperature being over 20 degrees C, and the irradiation lasted for 5 min. PAC was used as flocculant at the dose of 60 mgl(-1), jar tests were done to investigate the Chl alpha removal by flocculation. The results showed that ultrasound raised the water temperature instantly but did not lead to a regular pH change pattern in all the treated samples. Ultrasound could remove more than 90% of Chl alpha from raw water with temperature over 31 degrees C, but less than 20% of Chl alpha or even increased Chl alpha concentration in some samples with temperature lower than 31 degrees C. Compared with the algal removal effects by direct raw water flocculation with PAC, ultrasound did not enhance markedly the flocculation effects on algae removal, which was not in agreement with the findings reported. The reason might be due to morphology and characteristics of natural algae differed greatly from that of algae cultured in laboratory.

[The standardized practice of laparoscopic-assisted radical right hemicolectomy in order to achieve complete mesocolic excision].

OBJECTIVE: To explore the feasibility of laparoscopic-assisted radical right hemicolectomy with the outcome being a complete mesocolic excision (CME). METHODS: Between February 2010 and June 2011, we performed the standardized surgery of laparoscopic-assisted radical right hemicolectomy with an aim of CME on 14 patients. There were 10 males and 4 females, with an average age of 57 years (range 36 to 74 years). All the pathologic results in 14 cases were primary colonic adenocarcinoma. The TNM stages were distributed as follows: 2 in II A, 3 in II B, 3 in III A, 5 in III B and 1 in III C. RESULTS: Surgery was successfully performed for all patients without open conversion. The average operation time was (178 ± 37) minutes (range 127 to 221 minutes), average intraoperative blood loss was (67 ± 23) ml (range 30 to 110 ml), while the average number of lymph node harvest was 21 ± 7 (range 14 to 31), and the postoperative hospital stay was (10.0 ± 2.2) days (range 7 to 15 days). Minor complications occured in 2 patients. Major complications and post-operative mortality were not observed. All the patients were followed up for 3 to 19 months, no tumor recurrence or metastasis was identified. CONCLUSION: The standardized surgery of laparoscopic-assisted radical right hemicolectomy with the final outcome of CME is safe and feasible.

The effects of oral administration of d-modafinil on male rat ejaculatory behavior.

INTRODUCTION: Premature ejaculation (PE) is one of the most common forms of male sexual dysfunction. Examination of various classes of drugs on ejaculation latency would provide further opportunities for drug development in this field. AIM: This study was conducted to examine the effects of the d-isomer of modafinil (d-modafinil) on ejaculatory behavior in a rat model. METHODS: Male sexual behavior in the rat was examined after acute oral administration of d-modafinil (10 mg/kg, 30 mg/kg, and 100 mg/kg) in copulation studies with receptive females. MAIN OUTCOME MEASURES: The latency to ejaculation, post-ejaculatory interval, and the frequency of mounting behavior were measured. Results d-modafinil (30 mg/kg and 100 mg/kg) produced a significant delay in ejaculation. The delay in ejaculation was accompanied by an increase in the number of intromissions without any change in the mount or intromission latency. The possible mechanisms of action of d-modafinil to produce this delay in ejaculation are discussed. CONCLUSIONS: These results demonstrate that acute oral administration of d-modafinil can lengthen the latency to ejaculation in rats without suppressing sexual behavior. The greatest delay in ejaculation was observed in animals with shorter baseline ejaculatory latencies. Investigation into new classes of drugs that modulate ejaculation may provide new therapeutic options for treating.

Effect of pre-ozonation-enhanced coagulation on dissolved organic nitrogen in municipal wastewater treatment plant effluent.

Municipal wastewater treatment plant (WWTP) effluent is increasingly used as reclaimed water and as water sources for downstream areas. Effluent dissolved organic nitrogen (DON) is considered to be the precursor to nitrogen disinfection by-products (N-DBPs). Here, we investigated DON removal by pre-ozonation-enhanced coagulation and found that (1) pre-ozonation significantly enhanced the removal of DON, dissolved organic carbon (DOC), and UV254 by coagulation. (2) pH had an important impact on the pre-ozonation-enhanced coagulation. At lower pH, the removal of DON, DOC, and UV254 is higher. (3) As ozone dosage increased, zeta potential gradually increased, while dissolved calcium concentrations declined and there was a strong correlation between zeta potential and dissolved calcium concentrations. (4) Small (<6 kDa) molecular weight DON was dominant in the effluent. Hydrophilic and hydrophobic DON accounted for 58.5% and 30.8% of the total, respectively. (5) Coagulation reduced overall DBP formation potentials to less than 20%. In contrast, overall DBP formation potentials increased after ozonation. However, pre-ozonation-enhanced coagulation not only removed 71% DON, but also reduced overall DBP formation potentials by more than 40%. (6) 3-DEEM spectra indicated that DBP formation potentials and DON concentrations were related to three main peaks, which corresponded to tryptophan-based proteins, aromatic proteins, and fulvic acids.

[Mechanism of Pre-ozonation Enhanced Coagulation on DON in the Secondary Effluent].

Municipal wastewater effluent is increasingly used as reclaimed water and source water for downstream areas. Scholars are beginning to study the potential of dissolved organic nitrogen (DON) as a precursor to the formation of nitrogen disinfection by-products (DBP). In order to explore the mechanism of pre-ozonation coupled with enhanced coagulation on DON in the secondary effluent, the distributions of molecular weight and hydrophobicity/hydrophilicity of DON were analyzed. Disinfection by-product formation potential from chlorination was also investigated. Lastly, the composition and chemical structure of DON before and after coagulation were studied in combination with 3DEEM. Our results showed that pre-ozonation followed by coagulation with PACl significantly enhanced the removal of DON and mitigated DBP formation potentials. The following conclusions can be drawn from this study:① The tested effluent was very hard as indicated by total hardness and high calcium concentrations, and the pH had an important effect on pre-ozonation enhanced coagulation. As pH was decreased, the rates of DON, DOC and UV254 removal increased. At pH 6.2, the rate of DON removal was maximal, and a 3.7 fold increase in removal-rate was achieved. ② Calcium played a critical role in pre-ozonation enhanced coagulation. Zeta potentials and calcium concentrations were substantially affected at higher ozone doses. At ozone dosage of 8 mg·L-1, Zeta potentials increased from -33 to -8 mV, and calcium concentrations decreased from 116 to 89 mg·L-1. The ratio of calcium hardness to DOC was relatively high in this study, approaching 24 mg·mg-1 (CaCO3/DOC). Thus, pre-ozonation promoted the removal of DON by coagulation. ③ Large molecular weight and hydrophobic DON were easier to remove by coagulation. Ozonation modified the DON characteristics to become more hydrophilic and smaller in molecular weight. Coagulation reduced overall DBP formation potentials to less than 20%. Pre-ozonation enhanced coagulation decreased overall DBP formation potentials by more than 45%. ④ Finally, the 3DEEM spectra indicated that the formation potentials and DON characteristics, due to disinfection, were related to three main peaks, which corresponded to tryptophan-based proteins, aromatic proteins, and fulvic acids.

Effect of daily dosing duration of direct and indirect dopamine receptor agonists: cocaine cross-tolerance following chronic regimens.

One therapeutic paradigm for cocaine abuse is a 24-h 'agonist' treatment which reduces reinforcing effects in a manner similar to the methadone maintenance model for heroin. However, 24-h dosing of dopamine (DA) agonists may induce side effects of insomnia and psychosis, as well as anergia and anhedonia which may actually potentiate abuse. Thus, it is important to determine the daily dose duration of potential treatments such as direct (e.g. pramipexole) and indirect (e.g. GBR 12909) DA agonists, that may induce cross-tolerance with cocaine. We gave a cocaine challenge (15 mg/kg i.p.) on withdrawal day 7 and recorded ambulations and a behavioral rating. We found that 20- and 24-, but not 16-h, daily dosing with cocaine (40 mg/kg), for 14 days, induced tolerance. Pramipexole (4 mg/kg), administered for 24 but not 12 h per day, for 14 days, induced cocaine cross-tolerance while GBR 12909 (18 mg/kg), administered i.p. over 24 or 16 h a day, for 7 days, did not. Thus daily dosing duration is an important variable in consideration of stimulant abuse treatment.

Phosphorus limitation on bacterial regrowth in drinking water.

Assimilable organic carbon (AOC) test and bacterial regrowth potential (BRP) analysis were used to investigate the effect of phosphorus on bacterial regrowth in the drinking water that was made from some raw water taken from a reservoir located in northern China. It was shown that AOC of the drinking water samples increased by 43.9%-59.6% and BRP increased by 100%-235% when 50 microg/L PO4(3-)-P(as NaH2 PO4) was added alone to the drinking water samples. This result was clear evidence of phosphorus limitation on bacteria regrowth in the drinking water. This investigation indicated the importance of phosphorus in ensuring biological stability of drinking water and offered a novel possible option to restrict microbial regrowth in drinking water distribution system by applying appropriate technologies to remove phosphorus efficiently from drinking water in China.

[Early maternal deprivation decreases the immunological function of F1 generation offspring in mice].

OBJECTIVE: To explore the changes of immunological function in F1 generation offspring after suffering early maternal deprivation. METHODS: Using Wistar rats, the maternal deprivation models were established according to our previous study. Their F1 generation offspring were enrolled for this study. The mass and indexes of spleen and thymus were measured. The phagocytosis assay was used to detect the phagocytic function of peritoneal macrophages. The proliferation of T lymphocytes was detected by MTT assay. ELISA was employed to determine the IL-2 level in serum. RESULTS: The maternal deprivation decreased the mass and indexes of spleen and thymus of their offspring. The phagocytic function of macrophage, proliferation of T lymphocytes and IL-2 level in serum of F1 generation offspring were also reduced. CONCLUSION: The immunological function declines in F1 generation offspring after suffering early maternal deprivation in mice.

[Removal of DON in micro-polluted raw water by coagulation and adsorption using activated carbon].

Dissolved organic nitrogen as a precursor of new type nitrogenous disinfection by-products in drinking water attracted gradually the attention of scholars all over the world. In order to explore the mechanism of DON removal in micro-polluted raw water by coagulation and adsorption, water quality parameters, such as DON, DOC, NH4(+) -N, UV254, pH and dissolved oxygen, were determined in raw water and the molecular weight distribution of the DON and DOC was investigated. The variations in DON, DOC and UV254 in the coagulation and adsorption tests were investigated, and the changes of DON in raw water were characterized using three-dimensional fluorescence spectroscopy. The results showed that DON, DOC and UV254 were 1.28 mg x L(-1), 8.56 mg x L(-1), 0.16 cm(-1), and DOC/DON and SUVA were 6.69 mg x mg(-1), 1.87 m(-1) x (mg x L(-1))(-1) in raw water, respectively. The molecular weight distribution of the DON in raw water showed a bimodal distribution. The small molecular weight (< 6 000) fractions accounted for a high proportion of 68% and the large (> 20 000) fractions accounted for about 22%. The removal of DON, DOC and UV254 was about 20%, 26% and 70%, respectively, in the coagulation test and the dosage of coagulant was 10 mg x L(-1). The removal of DON, DOC and UV254 was about 60%, 35% and 100%, respectively, in the adsorption test and the dosage of activated carbon was 1.0 g. In the combination of coagulation and adsorption, the removal of DON and DOC reached approximately 82% and 64%, respectively. 3DEEM revealed that the variation of DON in the coagulation and adsorption tests depended intimately on tryptophan protein-like substances, aromatic protein-like substances and fulvic acid-like substances.

[Chlorination characteristic and disinfection by-product formation potential of dissolved organic nitrogen compounds in municipal wastewater].

In order to explore the chlorinated disinfection by-product formation potential and chemical structure of dissolved organic nitrogen compounds in municipal wastewater, the water quality parameters, such as DON, DOC, NH4(+) -N and UV254 etc, were determined in the secondary effluent and the molecular weight distribution of the DON was investigated before and after the reaction with chlorine. DBPs were determined by gas chromatography, and the changes of DON were characterized using Fourier transform infrared spectroscopy and three-dimensional fluorescence spectroscopy before and after the reaction with chlorine. The results showed that DON, DOC, NH4(+) -N and UV254 were 2.47 mg x L(-1), 14.45 mg x L(-1), 5.42 mg x L(-1) and 15.88 m(-1), and m(DOC)/m(DON) and SUVA were 5.85 mg x mg(-1) and 1.09 L x (m x mg)(-1) in the secondary effluent. After the reaction with chlorine, the proportion of small molecular weight (M(r) < 6 000) DON increased from 78% to 70% , and the proportion of large molecular weight (M(r) > 20 000) DON decreased from 21% to 14%. The medium molecular weight (M(r)6000-20000) DON accounted for a small proportion and was unchanged. Among the DBPs, the concentration of bromochloroacetonitrile was the highest, which was 6.887 microg x L(-1), and the concentration of trichloroacetonitrile was the lowest, which was only 0.217 microg x L(-1). In FTIR spectrum, the dominating bands were at 3 500-3 400, 2 260-2 200, 1 700-1 640, 1 500-1 450, 1 150-1 100 and 850-800 cm(-1) respectively before the reaction, and the 1 380-1 350 cm(-1) and 600-550 cm(-1) bands were the dominating bands in addition to the original absorbing regions after the reaction. 3DEEM revealed that the variation of DON depends intimately on tryptophan protein-like substances, aromatic protein-like substances and fulvic acid-like substances.

Dissolved organic nitrogen (DON) profile during backwashing cycle of drinking water biofiltration.

A comprehensive investigation was made in this study on the variation of dissolved organic nitrogen (DON) during a whole backwashing cycle of the biofiltration for drinking water treatment. In such a cycle, the normalized DON concentration (C(effluent)/C(influent)) was decreased from 0.98 to 0.90 in the first 1.5h, and then gradually increased to about 1.5 in the following 8h. Finally, it remained stable until the end of this 24-hour cycle. This clearly 3-stage profile of DON could be explained by three aspects as follows: (1) the impact of the backwashing on the biomass and the microbial activity; (2) the release of soluble microbial products (SMPs) during the biofiltration; (3) the competition between heterotrophic bacteria and nitrifying bacteria. All the facts supported that more DON was generated during later part of the backwashing cycle. The significance of the conclusion is that the shorter backwashing intervals between backwashing for the drinking water biofilter should further decrease the DON concentration in effluent of biofilter.

[Mechanism of NH(4+)-N removal in drinking water biofilter].

In order to explore the mechanism of NH(4+)-N removal in drinking water biofilter, water quality parameters, such as NH(4+)-N, NO(2-)-N, NO(3-)-N, total phosphorus, permanganate index, nitrogen gas, temperature and dissolved oxygen etc, were determined in the inflow and outflow of biofilter. Samples of granular activated carbon (GAC) at different height (0, 10, 20, 40, 60 cm) of the biofiter media were collected and analyzed for the bacterial community with molecular biology techniques. The bacterial diversity in the activated carbon biofilm sample was studied based on the phylogenetic analysis of sequences. The results showed that there were three stages according to the NH(4+)-N concentration in the influent. The "nitrogen loss" phenomenon (total inorganic nitrogen in the effluent was less than that in the influent) occurred at the first, second and third stages and the amount of nitrogen loss were 0.94, 0.32 and 0.15 mg x L(-1), respectively. The amount of nitrogen loss had a good positive correlation with the NH(4+)-N concentration in the influent, but not a linear relationship with the concentration of the permanganate index in the influent. The average concentrations of N2 increased gradually with the height of media in the biofilter, with values of 14.04 and 14.67 mg x L(-1) in the influent and the effluent, respectively. Based on the sequencing results, the ammonia-oxidizing bacteria (AOB) in the activated carbon biofilm were classified into three common genera: Nitrosococcus, Nitrosomonas and Nitrosospira. When the NH(4+)-N concentration in the influent was relatively high, the "nitrogen loss" phenomenon in biofilter was caused by the AOB.

Competing presynaptic and postsynaptic effects of ethanol on cerebellar purkinje neurons.

BACKGROUND: Ethanol has actions on cerebellar Purkinje neurons that can result either in a net excitation or in inhibition of neuronal activity. The present study examines the interplay of presynaptic and postsynaptic mechanisms to determine the net effect of ethanol on the neuronal firing rate of cerebellar Purkinje neurons. METHODS: Whole-cell voltage-clamp recording of miniature inhibitory postsynaptic currents (mIPSCs) from Purkinje neurons in cerebellar slices was used to examine the effect of ethanol on presynapticsynaptic release of gamma-aminobutyric acid (GABA) and glutamate. Extracellular recording was used to examine the net action of both presynaptic and postsynaptic effects of ethanol on the firing rate of Purkinje neurons. RESULTS: Under whole-cell voltage clamp, the frequency of bicuculline-sensitive miniature postsynaptic currents (mIPSCs) was increased dose-dependently by 25, 50, and 100 mM ethanol without any change in amplitude or decay time. Despite this evidence of increased release of GABA by ethanol, application of 50 mM ethanol caused an increase in firing in some neurons and a decrease in firing in others with a nonrandom distribution. When both glutamatergic and GABAergic influences were removed by simultaneous application of 6-cyano-7-nitroquinoxaline-2,3-dione and picrotoxin, respectively, ethanol caused only an increase in firing rate. CONCLUSIONS: These data are consistent with a dual action of ethanol on cerebellar Purkinje neuron activity. Specifically, ethanol acts presynaptically to increase inhibition by release of GABA, while simultaneously acting postsynaptically to increase intrinsic excitatory drive.

[Removing breast foreign body resulted from augmentation with polyacrylamide hydrogel injection and silicone prosthesis implantation at one stage].

OBJECTIVE: This study was to investigate an operation, in which removing breast cysts of foreign body resulted from augmentation with polyacrylamide hydrogel injection was performed simultaneously with silicone prosthesis implantation under SEPS endoscope in order to relieve tissue injury and increase the accuracy of clearance. METHODS: Eight patients were included in this study. Preoperative type B ultrasound examination was performed to mark the mass. Through an axillary approach, the cysts of foreign body that were distributed in the subcutaneous tissue, breast or muscle were separated and ablated under SEPS endoscope. After removal of the foreign body, a silicone implant was located submuscularly for breast augmentation. RESULTS: The operations were completed without hematoma and infection. Follow-up of the eight patients for 3 to 12 months showed that preoperative symptoms relating to the injected material, such as breast pain, lump and asymmetry, have no longer existed. The shapes of the breasts were satisfactory. CONCLUSIONS: We believe that endoscope-assisted mammoplasty offers more satisfactory clinical results with less injury, less morbidity, less scars, more accuracy and greater patient acceptance.

[Relation between phosphorus and bacterial regrowth in drinking water].

In the experiment, a bioassay called Bacterial Regrowth Potential (BRP) was used to investigate the effect of phosphorus on bacterial regrowth in the water sample that was made from some raw water taken from a reservoir located in northern China. It was shown that BRP of water sample increased about 100%-235% when 50 micrograms/L PO4(3-) -P (as NaH2PO4) was added alone. BRP of water sample with various inorganic nutrients (including phosphate) addition had the similar increase compared with BRP of water sample with only 50 micrograms/L PO4(3-) -P addition and BRP of water sample with acetate-C of 1 mg/L addition increased only 30%-40%. These results were clear evidence of phosphorus limitation on bacteria regrowth in the water sample investigated in the experiment. This observation offered novel possibility to restrict microbial regrowth in water distribution system by developing technologies to remove phosphorus efficiently from drinking water.