Uptake Rate of Ammonia-nitrogen With Sterile Ulva sp. for Water Quality Control of Intensive ShrimpCulture Ponds in Developing Countries

Ammonia-nitrogen uptake by seaweed was modeled based on the concept of ammonia-nitrogen permeation through cell membrane, and the derived model of uptake rate was experimentally verified. In this study, sterile Ulva sp. was employed as seaweed to treat model culture solution, and the distribution equilibrium of the ammonia-nitrogen between the culture solution and cell inside was measured to obtain the equilibrium. For this measurement, the seaweed was pretreated before the uptake runs to inhibit the assimilation by methionine sulfoximine for removal of the assimilation effects on the uptake rate. The parameters of the distribution equilibrium and permeation rate of ammonia-nitrogen were measured. The pretreated seaweed could uptake ammonia-nitrogen and the ammonia-nitrogen permeated through the cell membrane from the culture solution into the cell according to the concentration gradient. The seaweed saturated with ammonia-nitrogen was immersed in the culture solution without ammonia-nitrogen and it could excrete ammonia-nitrogen once taken in. In both cases of the uptake and excretion, the systems attained equilibrium after around 6 hours. The ammonia-nitrogen concentration in the cell increased with the concentration in the culture solution at equilibrium. The flux of ammonia-nitrogen was almost proportional to the concentration difference, defined as that between the ammonia-nitrogen concentration in the cell and the hypothetical concentration of ammonia-nitrogen in the cell which is in equilibrium with the culture solution. The overall permeation coefficient was measured as 9.1 · 10–3 m h–1 for both cases of uptake and excretion, and this relationship was valid when the concentration difference was large enough relative to the flux

Effects of Sterile Ulva sp. Growth Rate on Water Quality Control of Intensive Shrimp Culture Pond in Developing Countries

To control the water quality in the intensive shrimp mariculture pond by uptaking the total ammonia-nitrogen with sterile Ulva sp., the growth rate of sterile Ulva sp. was experimentally measured and the influence of the rate on the water quality control evaluated. The specific growth rate constant of the seaweed increased with the total ammonia-nitrogen concentration, photosynthetic photon flux density and operating temperature. Then the dynamics of ammonia-nitrogen in the modeled culture pond for the intensive shrimp farming in the tropical region were numerically simulated, in which the seaweed was used to uptake ammonia-nitrogen. The seaweed could uptake ammonia-nitrogen effectively during daytime mainly due to the high intensity of sun light, and the total ammonia-nitrogen concentration in the shrimp pond could be kept very low. The required seaweed density to control the total ammonia-nitrogen concentration less than the recommended maximum concentration of 1.0 ⋅ 10–3 kg N m–3 was estimated to be reasonable

Phase transitions of an intrinsic curvature model on dynamically triangulated spherical surfaces with point boundaries

An intrinsic curvature model is investigated using the canonical Monte Carlo simulations on dynamically triangulated spherical surfaces of size upto N=4842 with two fixed-vertices separated by the distance 2L. We found a first-order transition at finite curvature coefficient \alpha, and moreover that the order of the transition remains unchanged even when L is enlarged such that the surfaces become sufficiently oblong. This is in sharp contrast to the known results of the same model on tethered surfaces, where the transition weakens to a second-order one as L is increased. The phase transition of the model in this paper separates the smooth phase from the crumpled phase. The surfaces become string-like between two point-boundaries in the crumpled phase. On the contrary, we can see a spherical lump on the oblong surfaces in the smooth phase. The string tension was calculated and was found to have a jump at the transition point. The value of \sigma is independent of L in the smooth phase, while it increases with increasing L in the crumpled phase. This behavior of \sigma is consistent with the observed scaling relation \sigma \sim (2L/N)^\nu, where \nu\simeq 0 in the smooth phase, and \nu=0.93\pm 0.14 in the crumpled phase. We should note that a possibility of a continuous transition is not completely eliminated.Comment: 15 pages with 10 figure

Effects of Inhibitory Factor on Uptake Rate of Ammonia-Nitrogen with Sterile Ulva sp. for Water Quality Control of Intensive Shrimp Culture Ponds

Ammonia-nitrogen uptake by sterile Ulva sp. was studied for the control of culture pond water of intensive shrimp farming. The uptake rates were measured by batch and semi-continuous operations, and analyzed with the Michaelis-Menten model of uncompetitive inhibition. For the batch uptake operations, the Michaelis-Menten parameters were estimated, and the maximum rate and Michaelis constants were estimated as 3.4 × 10–2 kg kg–1 h–1 and 5.5 × 10–3 kg m–3, respectively. The inhibitory factor increased with the uptake time and with the decrease of the seaweed density. In the cases of semi-continuous operations, the seaweed could continuously treat with the model farming culture solution. Although the ratio of the seaweed density relative to the rate of ammonia-nitrogen generation should be appropriately adjusted to keep lower inhibitory factor in the seaweed, the ammonia-nitrogen concentration could be maintained at a relatively low level during operation. Then the ammonia-nitrogen uptake by the alga water was roughly simulated and operation with moderate density of the algae in the pond could maintain the ammonia-nitrogen concentration at a sufficiently low level in the shrimp farming pond. The suggested treatment process might be attractive to control pond water quality for intensive shrimp farming

Alcohol consumption and cigarette smoking in relation to high frequency of p53 protein accumulation in oesophageal squamous cell carcinoma in the Japanese

We investigated levels of p53 protein expression in Japanese patients with oesophageal squamous cell carcinoma. A significantly larger proportion of heavy alcohol drinkers and cigarette smokers was evident in the p53-positive group. The combination of drinking and smoking was associated with a high frequency of p53 protein accumulation. © 2000 Cancer Research Campaig

Moderately differentiated colorectal adenocarcinoma as a lymph node metastatic phenotype: comparison with well differentiated counterparts

<p>Abstract</p> <p>Background</p> <p>The differences between the metastatic property of moderately (Mod) and well (Wel) differentiated colorectal adenocarcinoma remain unclear. Since Mod is unable to form complete acini, therefore an epithelial-mesenchymal transition (EMT) can occur in that structure. Herein, we hypothesized that Mod metastasizes more easily than the Wel counterparts.</p> <p>Methods</p> <p>The medical records of 283 consecutive patients with Mod (n = 71) or Wel (n = 212) who underwent surgery were reviewed between January 1, 2001, and December 31, 2003, for actual 5-year overall survival. We examined the differences between the clinicopathological characteristics of the Mod and the Wel groups.</p> <p>Results</p> <p>The lymph node involvement (<it>p </it>< 0.0001), lymphatic permeation, venous permeation, depth of invasion, liver metastasis, and carcinomatous peritonitis were significantly higher in the Mod group in comparison to the Wel group. The independent risk factors by a logistic regression analysis for lymph node involvement were as follows: lymphatic permeation, liver metastasis, and Mod (<it>p </it>= 0.0291, Relative Risk of 1.991: 95% Confidence Interval: 1.073-3.697). A Kaplan-Meier survival curve showed that Mod had a trend towards a poor survival (<it>p </it>= 0.0517).</p> <p>Conclusion</p> <p>Mod metastasizes to the lymph nodes more easily in comparison to Wel. Therefore, patients with Mod may be considered the existence of lymph node involvement.</p