Bacterial community structures in MBRs treating municipal wastewater: relationship between community stability and reactor performance

Bacterial community structures in pilot-scale conventional membrane bioreactors (CMBRs) and hybrid MBRs (HMBRs) which were combined with pre-coagulation/sedimentation were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescence in situ hybridization (FISH) techniques. The results were compared with the community structure in a full-scale activated sludge (AS) process treating the same municipal wastewater. The Dice index (Cs) of similarity analysis of DGGE banding patterns demonstrated that the microbial community in AS was more similar to those in CMBR1 and CMBR2 than HMBR1 and HMBR2. This suggested that influent wastewater composition had a larger impact on bacterial community structures. Long-term community structure changes in the HMBRs and CMBRs were monitored and analyzed over 240 days by Non-metric multidimensional scaling (NMDS) analysis of DGGE banding patterns. The NMDS analysis revealed that both HMBRs and CMBRs had marked changes in community structures during the first about 100 days. Thereafter the perpetual fluctuations of bacterial community structures were observed in both HMBRs and CMBRs, even though the stable MBR performances (the performance was measured as membrane permeability and removal of dissolved organic carbon, DOC) were achieved. These results suggest that not only the stability, but also the adequate dynamics ("flexibility") of the bacterial community structure are important for the stable performance of the MBRs treating complex municipal wastewater.     

Development of stone tool use by wild chimpanzees (Pan troglodytes).

At the age of 3.5 years, wild chimpanzees at Bossou, Guinea, begin to use hammer and anvil stones to crack oil-palm nuts to get the kernels. To clarify the developmental processes, the authors did a field experiment in which stones and oil-palm nuts were provided. Infant chimpanzees' stone–nut manipulation was observed and video recorded. Data were collected from 3 infants younger than 4 years old from 1992 to 1995. The authors analyzed 692 episodes of infants' stone–nut manipulation and 150 episodes of infants' observation of nut cracking performed by adults. Infants observed other chimpanzees' nut cracking and got the kernels from them. The stone–nut manipulation developed from a single action on a single object to multiple actions on multiple objects. Although infant chimpanzees at the age of 2.5 years already acquired basic actions necessary for nut cracking, they did not combine the actions in an appropriate sequence to perform actual nut cracking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Limited bandwidth to affect processor design

This paper quantifies and compares the performance impacts of memory latencies and finite bandwidth. We show that the implementation of aggressive latency tolerance techniques aggravates stalls due to finite memory bandwidth, which actually become more significant than stalls resulting from uncongested memory latency alone. We expect that memory bandwidth limitations across the processor pins will drive significant architectural change. An execution-driven simulation measures the time that several SPEC95 benchmarks spend stalled for memory latency, limited-memory bandwidth and computing     

Preparation of inorganic-organic hybrid films containing particles using electrophoretic deposition method

The composite films of methylsiloxane inorganic-organic hybrid and MoS₂ particles have successfully been fabricated by electrophoretic deposition of MoS₂ particles in a mixed solution of methyl ethyl ketone (MEK) and inorganic-organic hybrid sol. The addition of 20 vol% hybrid sol into a MEK suspension increased the amount of MoS₂ deposition twice as much as that of MoS₂ deposition in MEK alone. The fraction of particles deposited on a substrate in MEK-20 vol% sol was estimated to be much larger than that in MEK. The hydrolyzed methyltriethoxysilane in a hybrid sol modified MoS₂ particles, resulting in lower negative zeta potential, which reduces the repulsion force among particles and makes the incorporation of particles into a deposition film easier. The surface modification also enables the incorporation of particles into a deposit by the interaction of surface modifiers. These factors enhance the incorporation of MoS₂ particles in electrophoretic deposition in MEK-sol.     

A diffusive badge sampler for volatile organic compounds in ambient air and determination using a thermal desorption-GC/MS system.

A sensitive personal badge sampler packed with Carbopack B for ambient levels of volatile organic compounds and an analytical system using a thermal desorption-preconcentration-GC/MS have been developed. The capacity of the new sampler was sufficient for an 8-h sampling period, and the analytical method was sensitive enough for the measurement of sub-ppb levels for a 2-h sampling period. The samplers were compared to diffusive samplers (OVM 3500) for typical environmental concentrations. There was a good correlation between the results obtained with the new samplers and the OVM samplers.     

Possible role of dentin matrix in region-specific deposition of cellular and acellular extrinsic fibre cementum

The mechanism whereby a region-specific deposition of the two types of cementum (cellular cementum and acellular extrinsic fibre cementum) is regulated on the growing root surface was tested using bisphosphonate-affected teeth of young rats and guinea pigs. The animals were injected subcutaneously with 8 or 10 mg P x kg body weight(-1) x day(-1) of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 1 or 2 weeks. In rat molars, HEBP prevented mineralization of newly formed root dentin matrix and totally inhibited de novo deposition of acellular extrinsic fibre cementum. Instead, thick cellular cementum was induced on the non-mineralized root dentin surface, irrespective of the position of the root. In both animals, cellular cementum was also induced on the non-mineralized surface of root analogue dentin in HEBP-affected incisors, where only acellular extrinsic fibre cementum is deposited under normal conditions. In normal rat molars, dentin sialoprotein (DSP) was concentrated along the dentin-cellular cementum border, but not that of dentin and acellular extrinsic fibre cementum. In HEBP-affected rat incisors, DSP was shown to penetrate through the non-mineralized dentin into the surrounding tissues, but not through the mineralized portions. These data suggest that, at the site of cellular cementum formation, putative inducing factors for cellular cementum might diffuse into the periodontal space through the newly deposited mantle dentin matrix before it is mineralized. At earlier stages of root formation, mantle dentin might mineralize more promptly not to allow such diffusion. The timing of mineralization of mantle dentin matrix might be the key determinant of the types of the cementum deposited on the growing root surface.     

In vitro fertilization and polyspermy in the pig: factors affecting fertilization rates and cytoskeletal reorganization of the oocyte

Polyspermy is a common phenomenon in the pig. Extensive information has become available from in vitro studies on not only the quality of oocytes but also the quality of spermatozoa. However, little information is available on the relative penetration rates of fresh and frozen spermatozoa from the same ejaculate from boars of different breeds. The present results, based on a total of 15 boars of three different breeds, revealed that the inter-breed variation in fertilization and polyspermic rates is larger than intra-breed variation. It was also shown that the incidence of polyspermy as well as penetration rate was greatly decreased by freezing and thawing, even if a higher number of sperm was coincubated with cumulus-free oocytes for a longer period compared to fresh sperm of the same ejaculate. This study focuses on the cytoskeletal organization of the oocyte with respect to the status of cumulus investment, and monospermic and polyspermic fertilization. The status of cumulus cells correlated with the density of transzonal cumulus-cell processes and with the maturation rate of oocytes and, to some degrees, the incidence of polyspermy. Polyspermic zygotes formed multiple microtubule domains in association with individual male pronuclei (PN), but in a high degree of polyspermy (more than trispermy), the pronuclear apposition did not proceed. The effect of multiple PN of paternal and maternal origin on the cytoskeletal reorganization is also discussed.     

Gel permeation chromatography using controlled-porosity glass. I. Polyacrylamide–formamide solution

The process of characterizing polyacrylamide and its partially hydrolyzed materials by gel permeation chromatography was examined. The use of controlled-porosity glass and formamide as the stationary phase and the eluent, respectively, resulted in chromatographic behavior in accord with the hydrodynamic volume concept for polyacrylamide fractions. The addition of a salt (KCl) to the eluent was found to retard the elution of the hydrolyzed polyacrylamide.     

High resolution for single-strand conformation polymorphism analysis by capillary electrophoresis

Since the successful completion of the Human Genome Project, increasing concern is being directed toward the polymorphic aspect of the genome and its clinical relevance. A form of single-strand DNA-conformation polymorphism analysis (SSCP) employing nondenaturing slab-gel electrophoresis (SGE) is applicable to the genetic diagnosis of bladder cancer from urine samples. To bring this technique into routine clinical practice, the use of capillary electrophoresis (CE) is naturally favorable in terms of speed and automation. However, the resolving power of SSCP, a prerequisite basis for reliability required in diagnostics, remains as a challenge for CE systems. We thus focused on this topic and conducted studies on CE instruments equipped with a single capillary or an array of multiple capillaries, using the resolution (Rs) as a quantitative scale for the resolving power. Polymer concentration and buffer are shown to be the decisive parameters. High Rs values of >2.5 are achieved for representative SNPs markers under the optimized conditions, without sacrificing such intrinsic advantages of CE over SGE as the 10-fold quicker migration time and operation that is reproducible, continuous, and automatic. The strategies presented broaden the limits of CE in both the current and related applications.