P-V-T properties of methyl chloride at high temperatures and pressures

"The equation of state of a gas describes the relation between the three variables pressure, volume, and temperature. Many equations have been proposed which accurately describe the p-v-T relations of real gases (3,4,5,8,18,20, 26,31,32,39,51,58,70,74,90). Some of these are purely empirical while others are derived from the intermolecular properties. A knowledge of the equation of state is necessary for obtaining equilibrium properties of pure substances. The volumetric behavior of non-polar gases may be described by the application of the principle of corresponding states, which has been successful in predicting compressibility factors and second virial coefficients for both pure gases and binary gas mixtures (19, 24, 25, 34, 35, 49, 54, 59, 63, 66, 67, 71). Polar gases deviate considerably from the principle of corresponding states, and require different treatment. Two methods have been used in predicting the second virial coefficient of polar gases. The first method uses statistical mechanics and an intermolecular potential function based on a physical model. The second method is based on a hypothesis, first proposed by Eucken (21), that polar gases undergo partial association due to dipole interaction or to hydrogen bonding, and that this is responsible for their deviation from the principle of corresponding states. This method of interpretation was originally applied by Alexander and Lambert to their results on acetaldehyde (1), and later by others to interpret the second virial coefficients (10,23,30,33,46,47). In this investigation the first approach was used to analyze the experimental second virial coefficient data. In this investigation, the Kihara core model was used to represent the geometry of a polar molecule. A permanent point dipole was placed in the core and used to represent the polar contribution to the molecular pair force field. Pople's perturbation method (68) was used to obtain an expression for the second virial coefficient of a polar gas. Numerical methods were then used to evaluate the potential parameters for nine polar gases. Derived thermodynamic properties of methyl chloride were also calculated from the calculated B(T) values for the modified Kihara potential and compared with those calculated from the p-v-T data."--Introduction

Coordination of Converter and Fuel Cell Controller

Abstract-Load-following fuel cell systems depend on control of reactant flow and regulation of DC bus voltage during load (current) drawn from them. To this end, we model and analyze the dynamics of a fuel cell system equipped with a compressor and a DC-DC converter. We then employ modelbased control techniques to tune two separate controllers for the compressor and the converter. We demonstrate that the lack of communication and coordination between the two controllers entails a severe tradeoff in achieving the stack and power output objectives. A coordinated controller is finally designed that manages the air and the electron flow control in an optimal way. Our results could be used as a benchmark of achievable fuel cell performance without hybridization

Liver transplantation for advanced hepatocellular carcinoma

There has been ongoing debate that the Milan criteria may be too strict that a significant number of patients who could benefit from liver transplantation (LT) might have been excluded. Based on this idea, various studies have been conducted to further expand the Milan criteria and give more HCC patients a chance of cure. In deceased donor LT (DDLT) setting, expansion of the criteria is relatively tempered because the results of LT for HCC should be comparable to those of patients with non-malignant indications. On the other hand, in living donor LT (LDLT) situation, liver grafts are not public resources. The acceptable target outcomes for LDLT might be much lower than those for DDLT. Patients with biologically favorable tumors might have excellent survivals after LT despite morphological advanced HCCs. Therefore, the significance and utility of biological tumor parameters for selecting suitable LT candidates have been increased to predict HCC recurrence after LT. Although there is no consensus regarding the use of prognostic biomarkers in LT selection criteria for HCC, the combination of conventional morphological parameters and new promising biomarkers could help us refine and expand the LT criteria for HCC in the near future

Proizvodnja antikomplementnih egzopolisaharida submerznim uzgojem gljive Flammulina velutipes

Seven species of basidiomycetes have been investigated for anti-complementary activity in hot water extracts and ethanol soluble fractions. Since Flammulina velutipes had the most potent activity, culture conditions for its mycelial growth were optimized to increase the production efficiency of anti-complementary exopolysaccharides. The optimal medium composition was (in g/L): galactose 15, sodium nitrate 5, glutamic acid 3, KH2PO4 2.5 and MgSO4·7H2O 0.6. Optimal production of anti-complementary activity was achieved at pH=3.5–5.5 and 25 °C. With these optimal medium and culture conditions, mycelial dry mass was maximized at 3.17 mg/mL after 6 days of cultivation in a 5-liter stirred-tank bioreactor, without pH control. The anti-complementary activity of exopolysaccharides increased sharply after 4 days of cultivation, and showed a high level at 5–6 days of cultivation. A periodate-labile carbohydrate moiety played a leading role in the anti-complementary activity exhibited by exopolysaccharide produced from F. velutipes. Results of tests on the anti-complementary activity in the absence of Ca²+ and immunoelectrophoresis indicated that the mode of complement activation by exopolysaccharide from F. velutipes is via both the classical and alternative pathways and that the activation degree is almost the same in each pathway.Istražena je antikomplementna aktivnost spojeva ekstrahiranih vrućom vodom i etanolom iz sedam vrsta gljiva stapčara. Optimirani su uvjeti uzgoja micelija gljive s najvećom aktivnosti, Flammulina velutipes, radi povećanja proizvodnje antikomplementnih egzopolisaharida. Optimalni sastav podloge bio je (u g/L): galaktoza 15, natrijev nitrat 5, glutamična kiselina 3, KH2PO4 2,5 i MgSO4·7H2O 0,6. Optimalna proizvodnja postignuta je pri pH=3,5-5,5 i 25 ºC. Pri tim uvjetima proizvedena je maksimalna količina suhe tvari od 3,17 mg/L nakon 6 dana uzgoja u bioreaktoru s miješalicom zapremnine 5 L, bez kontrole pH-vrijednosti. Antikomplementna aktivnost egzopolisaharida naglo se povećala nakon 4 dana, te je bila visoka nakon 5-6 dana uzgoja. Šećerni je ostatak, podložan djelovanju perjodata, glavni razlog antikomplementne aktivnosti egzopolisaharida gljive F. velutipes. Rezultati testiranja takve aktivnosti u odsutnosti Ca²+ iona i imunoelektroforeza upućuju na to da se komplementi egzopolisaharida iz F. velutipes aktiviraju klasičnim i alternativnim putem te da je stupanj aktivacije skoro jednak za oba puta

Green Tea Consumption and Stomach Cancer Risk: A Meta-Analysis

OBJECTIVES: Green tea has been suggested to have a chemopreventive effect against various cancers including stomach cancer. The aim of this study is to elucidate the relationship between green tea consumption and stomach cancer risk by meta-analysis. METHODS: Eighteen observational studies were identified using MEDLINE, THE COCHRANE LIBRARY, RISS, and a manual search. Summary relative risks/odds ratios (RR/ORs) for the highest versus non/lowest green tea consumption levels were calculated on the basis of fixed and random effect models. Subgroup analyses were used to examine heterogeneity across the studies. RESULTS: The combined results indicate a reduced risk of stomach cancer with intake of green tea (RR/OR=0.86, 95% CI=0.74-1.00). Subgroup analysis with six studies that reported differences between the highest and lowest consumption levels equal to or greater than five cups/day revealed a statistically significant protective effect (RR/OR=0.68, 95% CI=0.53-0.87). CONCLUSION: Green tea appears to play a protective role against the development of stomach cancer. The results also suggest that a higher level of green tea consumption might be needed for a clear preventive effect to appear. This conclusion, however, should be interpreted with caution because various biases can affect the results of a meta-analysis.ope