Improved energy recovery from dark fermented cane molasses using microbial fuel cells

A major limitation associated with fermentative hydrogen production is the low substrate conversion efficiency. This limitation can be overcome by integrating the process with a microbial fuel cell (MFC) which converts the residual energy of the substrate to electricity. Studies were carried out to check the feasibility of this integration. Biohydrogen was produced from the fermentation of cane molasses in both batch and continuous modes. A maximum yield of about 8.23 mol H₂/kg COD_removed was observed in the batch process compared to 11.6 mol H₂/kg COD_removed in the continuous process. The spent fermentation media was then used as a substrate in an MFC for electricity generation. The MFC parameters such as the initial anolyte pH, the substrate concentration and the effect of pre-treatment were studied and optimized to maximize coulombic efficiency. Reductions in COD and total carbohydrates were about 85% and 88% respectively. A power output of 3.02 W/m³ was obtained with an anolyte pH of 7.5 using alkali pre-treated spent media. The results show that integrating a MFC with dark fermentation is a promising way to utilize the substrate energy.     

Persistent organochlorine pesticide residues in milk and dairy products in India

Monitoring of milk and dairy product samples of various brands from different cities in Maharashtra, India, was carried out to determine if there is any contamination due to organochlorine pesticide residues. The measurements were made using a gas chromatograph-electron capture detector system. Trace levels of DDT and HCH were detected in the samples. Total HCH levels in milk and milk product samples were lower than total DDT levels, which could be attributed to earlier extensive antimalaria sanitary activities. Butter had higher levels of DDT than cheese and milk powder. All levels of organochlorine pesticide residues in milk and milk products were well below the maximum permissible limits given by the FAO/WHO. More importantly, as compared with an earlier report, present levels of the contaminants are substantially lower, which indicate the gradual phase out of these compounds.     

Destruction of formic acid using high frequency cup horn reactor

Degradation of formic acid has been studied in a high frequency cup horn type reactor with an aim of understanding the effect of operating parameters on the destruction efficiency. The methodology used in the work serves as a useful guideline for the optimization exercise for the sonochemical reactors to establish a set of operating parameters at large scale operation for achieving maximum efficiency. Firstly energy efficiency of the reactor has been established as a function of the operating volume with an aim of optimization of the capacity of the reactor for maximum extent of degradation. It has been observed that maximum transfer of supplied power is obtained at 300 ml capacity and hence the actual degradation studies have been performed with this operational capacity. The effect of time of irradiation, initial concentration of the pollutant, stirrer speed, presence of sodium sulfite (to scavenge the initial dissolved oxygen) on the extent of degradation has been investigated. Maximum extent of degradation has been observed under the conditions of 500 mg/l initial concentration, 200 rpm stirrer speed and presence of initial dissolved oxygen (no sodium sulfite in the system). Process intensification studies have been carried out using sodium chloride over a range of initial concentration and it has been observed that maximum extent of degradation of formic acid is obtained at 4% NaCl concentration. Comparison has been also made with different sonochemical configurations operating at lower frequency of irradiation (typically in the range of 20-50 kHz) with an aim of comparing the efficacies of the reactor at equivalent power consumption.     

Precipitation scavenging of polycyclic aromatic hydrocarbons in Mumbai, India

The concurrent rain and air sampling was conducted for thirteen rain events between the last week of May and end of June 2001. Concentration of total PAHs varied from 84.25 to 777.49 ng/l whereas that in air was in the range of 4.05 to 34.42 ng/m(3). In rainwater the lower molecular weight PAHs (e.g. Phenanthrene, Fluoranthene and Pyrene) were found to be more prominent than the higher molecular weight compounds. The gas phase scavenging ratio (Wg) was found to increase with the molecular weight of the compound. The particle phase scavenging ratio (Wp) values for the more volatile PAHs were generally much higher than those for less volatile PAHs. The higher MW PAHs have Wg values equal to or larger than their Wp values.     

Electrical conductivity,thermoelectric power and dielectric constant of a Gd2Ti2O7 single crystal

Electrical conductivity, thermoelectric power and dielectric constant of a Gd₂Ti₂O₇ single crystal have been studied in the temperature range 300–1000 K. Gd₂Ti₂O₇ is found to be an-type semiconductor with energy band gap 1.5 eV. It exhibits an extrinsic nature up to 675 K and an intrinsic nature above 675 K. The thermoelectric power increases with temperature in the region 300–675 K whereas it decreases with temperature in the region 675–1000 K. The dielectric constant increases slowly in the temperature range 300–675 K but this increase becomes fast in the temperature range 675–1000 K.     

Effects of Clinorotation on Growth and Chlorophyll Content of Rice Seeds

Microgravity, as a different environment, has been shown to affect plant growth and development (Sievers et al. 1996; Sack 1997). In the present study, effects of slow clinorotation (2 rpm) on growth and chlorophyll content in rice (variety: PRH-10) seedlings were investigated. Rice seeds were clinorotated continuously for 3, 5 and 7 days under ambient conditions. Root and shoot lengths and weights of rice seedlings were measured on the third, fifth and seventh day. Chlorophyll was extracted using N, N-Dimethylformamide (DMF). Absorption and fluorescence spectra of chlorophyll were recorded. Chlorophyll a, chlorophyll b and total chlorophyll contents were calculated from absorption spectra using Arnon’s method. Results showed an increase in root and shoot lengths in clinorotated samples. Similar results were obtained for root and shoot weights. Absorption spectra of chlorophyll showed no shift in the absorption peaks. Chlorophyll content was increased in clinorotated samples as compared to the controls. Interestingly, the difference between chlorophyll content in control and clinorotated samples decreased as the number of days of clinorotation increased. Chlorophyll a/b ratio was lowered in clinorotated samples as compared to the controls. These results suggest that slow clinorotation (2 rpm) affects plant growth and chlorophyll content in rice seedlings.     

Variance of least squares estimators for a damped sinusoidalprocess

The variance of least squares estimators for the parameter estimation of a damped sinusoidal process is analyzed, based on first-order perturbation. Analytical expressions for the variances of the frequency, damping factor, amplitude, and phase estimators are derived. Explicit expressions are given for both damped and undamped single-mode cases. The effect of mode separation on the accuracy is investigated through the two-mode case. The dependence of the variances on number of data points, model order, signal-to-noise ratio, and mode separation is investigated, both analytically and numerically, for practical applications. Extensive Monte Carlo simulation results are given to verify, enhance, and illustrate the analytical expressions     

Polyadenylation of stable RNA precursors in vivo

Polyadenylation at the 3' terminus has long been considered a specific feature of mRNA and a few other unstable RNA species. Here we show that stable RNAs in Escherichia coli can be polyadenylated as well. RNA molecules with poly(A) tails are the major products that accumulate for essentially all stable RNA precursors when RNA maturation is slowed because of the absence of processing exoribonucleases; poly(A) tails vary from one to seven residues in length. The polyadenylation process depends on the presence of poly(A) polymerase I. A stochastic competition between the exoribonucleases and poly(A) polymerase is proposed to explain the accumulation of polyadenylated RNAs. These data indicate that polyadenylation is not unique to mRNA, and its widespread occurrence suggests that it serves a more general function in RNA metabolism.     

Primary pulmonary plasmacytoma

BACKGROUND: A patient was diagnosed with an extramedullary plasmacytoma of the lung after complete resection of the mass at thoracotomy. Immunoperoxidase staining of the mass revealed monoclonal lambda chains. Screening for multiple myeloma identified a small amount of M-protein in the blood, but no other evidence of multiple myeloma was found. METHODS: A literature search was conducted to determine the prognosis and the best way to manage the patient. RESULTS: Nineteen cases of primary pulmonary plasmacytoma were found in the literature. The age range was 3-79 years. Most of these cases were diagnosed at thoracotomy and treated by surgical excision. Immunohistochemical evaluation of the lesion is essential for diagnosis but was done in only three cases. CONCLUSIONS: Surgery and radiation therapy seem to be equally effective forms of treatment. The role of adjuvant chemotherapy is unknown. Local recurrences are rare. Follow-up data were inadequate to determine disease-free survival, progression to multiple myeloma, and overall survival in primary pulmonary plasmacytoma. Close follow-up is needed to detect progression.