Anaerobic methane oxidation and aerobic methane production in an east African great lake (Lake Kivu)

We investigated CH₄ oxidation in the water column of Lake Kivu, a deep meromictic tropical lake with CH₄-rich anoxic deep waters. Depth profiles of dissolved gases (CH₄ and N₂O) and a diversity of potential electron acceptors for anaerobic CH₄ oxidation (NO₃^?, SO₄^2?, Fe and Mn oxides) were determined during six field campaigns between June 2011 and August 2014. Denitrification measurements based on stable isotope labelling experiments were performed twice. In addition, we quantified aerobic and anaerobic CH₄ oxidation, NO₃^? and SO₄^2? consumption rates, with and without the presence of an inhibitor of SO₄^2?-reducing bacteria activity. Aerobic CH₄ production was also measured in parallel incubations with the addition of an inhibitor of aerobic CH₄ oxidation. The maximum aerobic and anaerobic CH₄ oxidation rates were estimated to be 27?±?2 and 16?±?8?μmol/L/d, respectively. We observed a difference in the relative importance of aerobic and anaerobic CH₄ oxidation during the rainy and the dry season, with a greater role for aerobic oxidation during the dry season. Lower anaerobic CH₄ oxidation rates were measured in presence of molybdate in half of the measurements, suggesting the occurrence of linkage between SO₄^2? reduction and anaerobic CH₄ oxidation. NO₃^? consumption and dissolved Mn production rates were never high enough to sustain the measured anaerobic CH₄ oxidation, reinforcing the idea of a coupling between SO₄^2? reduction and CH₄ oxidation in the anoxic waters of Lake Kivu. Finally, significant rates (up to 0.37?μmol/L/d) of pelagic CH₄ production were also measured in oxygenated waters.     

Simple automatic initiator for microwave induced plasmas

A simple circuit is described which is used to maintain continuity of a radio-frequency or microwave induced plasma. The microwave power reflected from the discharge is monitored. Upon an increase of the reflected power which indicates that the plasma has become extinguished, a high-voltage pulse is applied to a coil wrapped around the discharge region. The repetition rate, voltage of the pulse, and threshold of reflected power are adjustible. This circuit is applicable to resonance fluorescence, atomic absorption and emission, and kinetic determinations.     

Optimal inlet temperature control of reactors with catalyst decay

The constant conversion policy which has been shown to be optimal in certain classes of optimal control problems for reactors with decaying catalyst is examined here for the inlet temperature control in a tubular reactor where the catalyst decay is a function of the composition. A single irreversible reaction is considered where the rate expression is a product of separate functions of temperature, concentration or conversion and catalyst activity. The catalyst decay rate expression is also a product of separate functions of the same variables. A proof of the constant exit conversion property is given for problems where the decay rate is of first-order with respect to the catalyst activity.     

Determination of sucrose polyesters by high performance gel permeation chromatography

Sucrose polyester (SPE) in feces and diets is determined by freeze-drying the samples, extracting with ethyl ether, and subjecting the extracts to high performance gel permeation chromatography with tetrahydrofuran as solvent. SPE elutes as a single peak before other components of the extract, and is quantitated by a refractive index detector. The relative standard deviation for samples containing 11–60% SPE (dry weight basis) is 2%. The SPE is a mixture of sucrose hexa-, hepta-, and octa-esters with C₁₆ and C₁₈ fatty acids.     

Prediction of metabolic clusters in early-lactation dairy cows using models based on milk biomarkers

The aim of this study was to describe metabolism of early-lactation dairy cows by clustering cows based on glucose, insulin-like growth factor I (IGF-I), free fatty acid, and β-hydroxybutyrate (BHB) using the k-means method. Predictive models for metabolic clusters were created and validated using 3 sets of milk biomarkers (milk metabolites and enzymes, glycans on the immunogamma globulin fraction of milk, and Fourier-transform mid-infrared spectra of milk). Metabolic clusters are used to identify dairy cows with a balanced or imbalanced metabolic profile. Around 14 and 35 d in milk, serum or plasma concentrations of BHB, free fatty acids, glucose, and IGF-I were determined. Cows with a favorable metabolic profile were grouped together in what was referred to as the “balanced” group (n = 43) and were compared with cows in what was referred to as the “other balanced” group (n = 64). Cows with an unfavorable metabolic profile were grouped in what was referred to as the “imbalanced” group (n = 19) and compared with cows in what was referred to as the “other imbalanced” group (n = 88). Glucose and IGF-I were higher in balanced compared with other balanced cows. Free fatty acids and BHB were lower in balanced compared with other balanced cows. Glucose and IGF-I were lower in imbalanced compared with other imbalanced cows. Free fatty acids and BHB were higher in imbalanced cows. Metabolic clusters were related to production parameters. There was a trend for a higher daily increase in fat- and protein-corrected milk yield in balanced cows, whereas that of imbalanced cows was higher. Dry matter intake and the daily increase in dry matter intake were higher in balanced cows and lower in imbalanced cows. Energy balance was continuously higher in balanced cows and lower in imbalanced cows. Weekly or twice-weekly milk samples were taken and milk metabolites and enzymes (milk glucose, glucose-6-phosphate, BHB, lactate dehydrogenase, N-acetyl-β-d-glucosaminidase, isocitrate), immunogamma globulin glycans (19 peaks), and Fourier-transform mid-infrared spectra (1,060 wavelengths reduced to 15 principal components) were determined. Milk biomarkers with or without additional cow information (days in milk, parity, milk yield features) were used to create predictive models for the metabolic clusters. Accuracy for prediction of balanced (80%) and imbalanced (88%) cows was highest using milk metabolites and enzymes combined with days in milk and parity. The results and models of the present study are part of the GplusE project and identify novel milk-based phenotypes that may be used as predictors for metabolic and performance traits in early-lactation dairy cows.     

Differential partitioning of tRNAs between micellar and aqueous phases: a convenient gel filtration method for separation of tRNAs

A case of Blue Rubber Bleb Nevus in a 11 year-old boy is reported. The patient exhibited characteristic hemangiomas of the skin and gastrointestinal tract with an iron deficiency anemia. Historical, clinical, pathological, and surgical features of the condition are discussed. Value of fibroscopic examination in delineation of the cause of persistent gastrointestinal bleeding is pointed out.     

The artificial heart. Progress and promise

A multidisciplinary group has designed, fabricated, and evaluated an artificial heart. The heart consists of two smooth-surfaced sac-type pumps, two pneumatic power units, and an electronic control system. The artificial heart has been employed in 22 calves. A variety of problems have been encountered and overcome and a significant improvement in pump design has been made. As a result, a gradual increase in survival times has occurred. The last two calves in which the heart was tested lived for 60 and 42 days respectively. These animals ate well and gained weight. The ability of the control system to balance the output of the two pumps over long periods of time and to automatically increase cardiac output with treadmill exercise has been confirmed. No insurmountable problems in the development of the artificial heart have been identified. The date that an artificial heart will be available for clinical use depends on the availability of funds and on the tenacity of the investigators.     

Antibody-induced antigen redistribution and shedding from human breast cancer cells

Cell surface antigens of human breast cancer cells undergo a rapid redistribution when bound by antibodies from cancer patients. The subsequent shedding of these antigen-antibody complexes and free antigen may be instrumental in tumor survival.