Inhibition of Total Gas and Methane Production in Anaerobic Digestion by Various Toxicants

Heavy metal inhibition of anaerobic digestion of municipal sewage sludge has been investigated over the past 50 years. Many assays began with steady-state conditions and observed the rate at which total gas or methane production decreased due to toxicant inhibition. These methods required considerable time and labor. Modified Warburg respirometers and serum bottle assays reduced much of the effort, but each method has limitations in terms of complexity, cost, and accuracy. This series of experiments had two objectives: 1) develop a quick, inexpensive, and easy method to measure methanogenic activity in anaerobic digesters, and 2) determine median inhibitory concentrations (IC50) of selenium, copper, chromium, zinc, mercury, lead, and cobalt to total gas and methane production in batch anaerobic digesters. Preliminary experiments indicated a linear increase in gas production during community recovery from oxygen inhibition. The rate of increase was relatively independent of substrate quality during the first 6 hr as long as no nutrients were limiting. Toxicants introduced immediately after reestablishment of anaerobic conditions reduced the rate of gas production recovery as a linear function of toxicant concentration. Anaerobic sludge samples taken from the primary digester of the local wastewater treatment plant were supplemented with cow manure, dry dogfood, and ammonium acetate prior to immediate use. Five liter portions in 10 x 70 cm (4 x 28 in) PVC sewer pipe segments were agitated on a rotary shaker and toxicants were added immediately after reestablishment of anaerobic conditions. Total gas production rates (determined through displacement of 10% NaCl solution in 50 mL burets) and percent methane in headspace gases (determined by gas chromatography) were measured 6 hr later. IC50 values for total gas and methane production were determined from linear least squares line equations derived from inhibition as a percent of the control. Results indicated that chromium, selenium, copper, and zinc were relatively equal in terms of toxicity to total gas production and methanogenesis. Calculated IC50 values for reduction of total gas production were 123, 133, 115, and 122 mgL-1, respectively. IC50 values for reduction of methane in headspace gas were 102, 118, 114, and 170 mgL-1, respectively. Correlation coefficients (r) for the line equations of these four toxicants ranged between 0.9733 and 0.9980. Mercury was slightly less toxic with IC50 values of 286 and 254 mgL-1 for reduction of total gas and methane production, respectively. Line equation correlation coefficients were 0.9677 and 0.9919 for these values. Lead and cobalt were the least inhibitory elements examined and median inhibitory concentrations were greater than the maximum concentration tested (400 mgL-1). Extrapolated IC50 values for lead were 410 and 405 mgL-1 for total gas and methane production, respectively. Cobalt showed very little inhibition with IC50 values estimated at 551 and 1106 mgL-1 for total gas and methane production, respectively. Correlation coefficients for lead and cobalt line equations used to calculate IC50 values ranged between 0.8331 and 0.9609

The Saccharomyces cerevisiae SEC14 Gene Encodes a Cytosolic Factor That Is Required for Transport of Secretory Proteins from the Yeast Golgi Complex

We have obtained and characterized a genomic clone of SEC14, a Saccharomyces cerevisiae gene whose product is required for export of yeast secretory proteins from the Golgi complex. Gene disruption experiments indicated that SEC14 is an essential gene for yeast vegetative growth. Nucleotide sequence analysis revealed the presence of an intron within the SEC14 structural gene, and predicted the synthesis of a hydrophilic polypeptide of 35 kD in molecular mass. In confirmation, immunoprecipitation experiments demonstrated SEC14p to be an unglycosylated polypeptide, with an apparent molecular mass of some 37 kD, that behaved predominantly as a cytosolic protein in subcellular fractionation experiments. These data were consistent with the notion that SEC14p is a cytosolic factor that promotes protein export from yeast Golgi. Additional radiolabeling experiments also revealed the presence of SEC14p-related polypeptides in extracts prepared from the yeasts Kluyveromyces lactis and Schizosaccharomyces pombe. Furthermore, the K. lactis SEC14p was able to functionally complement S. cerevisiae sec14ts defects. These data suggested a degree of conservation of SEC14p structure and function in these yeasts species

Dimensionality effects on transition state resonances for H+DH and D+HD reactive collisions

The transition state resonances of the title reactions have been studied on the accurate double many-body expansion (DMBE) potential energy surface for H3 using two-dimensional (2D) and three-dimensional (3D) time-dependent wave packet propagation methods. It is shown that the resonance energies are strongly associated with the vibrational threshold states of the molecular fragment obtained upon dissociation, both in the 2D and 3D calculations. However, although the two systems have the same threshold states, the resonance widths for the 2D D+HD collisions are found to be considerably narrower than for the 3D ones, while no such phenomenon is observed for H+DH. As a result, we have concluded that there is an apparent dimensional effect on the resonance widths of the heavy-light-heavy (HLH) reaction.http://www.sciencedirect.com/science/article/B6TGT-3Y6H16X-B/1/4253a179e22a333236b87dd9066f7e7

Photoreactive Crystalline Quasiracemates

Rationally designed racemic and quasiracemic sulfonamidecinnamic acids assemble to give hydrogen-bonded dimers with coplanar alignment of neighboring olefins. The quasiracemate phase contains near inversion-related motifs with chemically distinct components forming supramolecular heterodimers that undergo asymmetric photodimerization

The Emerging Role of Robotics in Home Health Care

The demand for health care continues to exceed the supply of affordable, accessible care due in large part to the rapidly aging baby boomer population. The advancing field of robotics can provide an effective solution to this problem. This study aimed to develop a set of user requirements for a personal home health care robot. To generate these requirements, we conducted nine interviews with robotics professionals and three different focus groups with current and future caregivers and the elderly. Using this data we identified prominent and desired functionalities of robots, as well as what may influence their acceptance into the home setting. Our findings indicate that monitoring robots have the biggest acceptance potential among elderly and caregivers

Photoreactive Crystalline Quasiracemates

Rationally designed racemic and quasiracemic sulfonamidecinnamic acids assemble to give hydrogen-bonded dimers with coplanar alignment of neighboring olefins. The quasiracemate phase contains near inversion-related motifs with chemically distinct components forming supramolecular heterodimers that undergo asymmetric photodimerization

Serum protein profile in systemic-onset juvenile idiopathic arthritis differentiates response versus nonresponse to therapy

Systemic-onset juvenile idiopathic arthritis (SJIA) is a disease of unknown etiology with an unpredictable response to treatment. We examined two groups of patients to determine whether there are serum protein profiles reflective of active disease and predictive of response to therapy. The first group (n = 8) responded to conventional therapy. The second group (n = 15) responded to an experimental antibody to the IL-6 receptor (MRA). Paired sera from each patient were analyzed before and after treatment, using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). Despite the small number of patients, highly significant and consistent differences were observed before and after response to therapy in all patients. Of 282 spectral peaks identified, 23 had mean signal intensities significantly different (P < 0.001) before treatment and after response to treatment. The majority of these differences were observed regardless of whether patients responded to conventional therapy or to MRA. These peaks represent potential biomarkers of active disease. One such peak was identified as serum amyloid A, a known acute-phase reactant in SJIA, validating the SELDI-TOF MS platform as a useful technology in this context. Finally, profiles from serum samples obtained at the time of active disease were compared between the two patient groups. Nine peaks had mean signal intensities significantly different (P < 0.001) between active disease in patients who responded to conventional therapy and in patients who failed to respond, suggesting a possible profile predictive of response. Collectively, these data demonstrate the presence of serum proteomic profiles in SJIA that are reflective of active disease and suggest the feasibility of using the SELDI-TOF MS platform used as a tool for proteomic profiling and discovery of novel biomarkers in autoimmune diseases