The effects of digestion temperature and temperature shock on the biogas yields from the mesophilic anaerobic digestion of swine manure.

In order to obtain basic design criteria for anaerobic digesters of swine manure, the effects of different digesting temperatures, temperature shocks and feed loads, on the biogas yields and methane content were evaluated. The digester temperatures were set at 25, 30 and 35 degrees C, with four feed loads of 5%, 10%, 20% and 40% (feed volume/digester volume). At a temperature of 30 degrees C, the methane yield was reduced by only 3% compared to 35 degrees C, while a 17.4% reduction was observed when the digestion was performed at 25 degrees C. Ultimate methane yields of 327, 389 and 403 mL CH(4)/g VS(added) were obtained at 25, 30 and 35 degrees C, respectively; with moderate feed loads from 5% to 20% (V/V). From the elemental analysis of swine manure, the theoretical biogas and methane yields at standard temperature and pressure were 1.12L biogas/g VS(destroyed) and 0.724 L CH(4)/g VS(destroyed), respectively. Also, the methane content increased with increasing digestion temperatures, but only to a small degree. Temperature shocks from 35 to 30 degrees C and again from 30 to 32 degrees C led to a decrease in the biogas production rate, but it rapidly resumed the value of the control reactor. In addition, no lasting damage was observed for the digestion performance, once it had recovered.

Application of a sponge media (BioCube) process for upgrading and expansion of existing caprolactam wastewater treatment plant for nitrogen removal.

For the upgrade and expansion of an existing caprolactam wastewater treatment plant, a freely floating sponge media (BioCube) process was selected based on extensive pilot-plant tests, due to extreme space constraints. In order to protect nitrifier inhibition caused by high strength organics in caprolactam wastewater, the pilot plant consisted of an organics removal reactor, which functioned as a pretreatment for nitrification, and followed the nitrogen removal reactor. The suspended MLSS was 1,800-4,000 and the media attached MLSS was maintained at 22,000-26,000 mg/L. The final effluent COD was noticeably low, around 20.4-37 mg/L, even with fairly large fluctuations in the feed levels, between 1,400-6,770 mg/L. The removal of total nitrogen with the system, when denitrification was close to completion, was approximately 97.6%. For the entire run, complete nitrification of 99.6% was achieved, which might have been due to well-acclimatized nitrifiers attached in the BioCube media. Specifically, after adaptation, the nitrification continuously increased in the organics removal reactor, even under high residual organics conditions. From the numerous experimental results, the BioCube process seemed to be an effective method for the upgrading and expansion of the existing wastewater treatment plant, with minimum reactor enlargement.

Integrated biological and electro-chemical treatment of swine manure.

A full-scale biogas plant was applied to the processing of 10 m3/d of swine manure. The plant consisted of an anaerobic digester and an engine-generator. The digester operation resulted in an 81% of COD removal, a 55% of VS reduction, and methane-rich biogas production that is used to generate electrical and thermal energies. To further treat the digested manure, for compliance with discharge limits, an electro-chemical oxidation with a dimensionally sable anode was investigated for the simultaneous elimination of both the remaining COD and ammonia nitrogen. It was able to reduce NH4+-N levels from as high as 1552 down to 25 mg/L in 160 min, and the COD from 1542 to 0.21 mg/L under the experimental conditions of 8 V, 30 A and 20,000 microS/cm. The amount of electricity required for a 90% removal of the residual COD and ammonia in 1 m3 of filtered digester manure, via electrochemical oxidation, were approximately 153 and 151 kWh, respectively. These values exceed the maximum potential capacity of the biogas-originated electricity through the digestion of swine manure containing normal VS content. However, approximately 50% of the required electricity for the electrochemical oxidation could be supplied from the engine-generator.

Apoptosis and proliferation in hepatocarcinogenesis related to cirrhosis.

BACKGROUND: Dysplastic nodules (DNs) recently have been identified as preneoplastic lesions of hepatocellular carcinoma (HCC). To test an alternative hypothesis regarding DN development, in which we have suggested that DNs develop as an infiltrating clonal expansion in advance of, or parallel to cirrhosis, the authors investigated the rates of apoptosis and proliferation in human hepatocarcinogenesis. METHODS: The authors performed terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay and proliferation cell nuclear antigen (PCNA) staining in 11 low-grade DNs, 8 high-grade DNs including 3 cases with HCC subnodules, 10 small HCCs, and 29 cases of surrounding cirrhotic nodules. Hepatocellular carcinoma subnodules were present in three cases of high DNs. They determined TUNEL-labeling indices (LIs) and PCNA-LIs as the percentage of positive hepatocyte nuclei per 500 randomly counted cells. RESULTS: TUNEL-LIs (mean +/- standard deviation) were 0.8 +/- 0.82 in cirrhotic nodules, 1.0 +/- 0.98 in low-grade DNs, 3.0 +/- 4.33 in high-grade DNs, 8.7 +/- 7.71 in HCC subnodules of high-grade DNs, and 3.2 +/- 3.58 in small HCCs. The peak values of apoptotic activity were higher in high-grade DNs and HCCs than in low-grade DNs and cirrhotic nodules. Each case of low-grade DN showed a low to medium level of apoptotic activity when compared with those of the four surrounding cirrhotic nodules. The PCNA-LIs were 2.6 +/- 1.35 in cirrhotic nodules, 4.5 +/- 2.31 in low-grade DNs, 15.3 +/- 10.50 in high-grade DNs, 25.4 +/- 5.25 in HCC subnodules of high-grade DNs, and 34.9 +/- 15.70 in small HCCs. The peak values gradually increased, although only HCC showed significantly elevated proliferation activity. The differences of PCNA-LIs and TUNEL-LIs, measured in each case, were 1.7 +/- 1.89 in cirrhotic nodules, 3.6 +/- 2.43 in low-grade DNs, 7.9 +/- 5.69 in high-grade DNs, 16.2 +/- 2.87 in HCC subnodules of high-grade DNs, 28.2 +/- 13.97 in small HCCs. At all stages of hepatocarcinogenesis, the rates of cell proliferation were higher than apoptosis, allowing a preferential net gain of (pre)neoplastic cells, and it was significantly increased in small HCCs. In regenerative cirrhotic nodules, 14% (4 cases) showed higher rates of apoptosis than proliferation. CONCLUSIONS: The regulation/dysregulation of apoptosis of (pre)neoplastic cells as well as of proliferation may play an important role in the process of hepatocarcinogenesis.

Solution structure of a new hypothalamic neuropeptide, human hypocretin-2/orexin-B.

Orexin-A and orexin-B (also called hypocretin-1 and hypocretin-2, respectively) are novel hypothalamic neuropeptides encoded by a single mRNA transcript; they stimulate food intake. We have determined the three-dimensional solution structure of human hypocretin-2/orexin-B using two-dimensional 1H-NMR data and dynamical simulated annealing calculations. On the basis of NOEs, 3JHNalpha coupling constants and hydrogen-deuterium exchange rates together with chemical shift indices, human hypocretin-2/orexin-B was deduced to consist of two alpha-helices connected with a short linker in both H2O and 30% trifluoroethanol solutions. The helical axis of helix I is oriented about 60-80 degrees relative to helix II. Hybrid distance geometry and simulated-annealing protocols were used to generate an ensemble of 30 structures with no constraint violations greater than 0.03 nm for distances and 3 degrees for angles. In addition, human hypocretin-2/orexin-B shares a similar secondary-structural motif with human neuropeptide Y. This result can form the basis for further study on ligand-receptor recognition of human orexin receptors.