Biomedical subjects

Baoming Li

Publications and source records attributed to Baoming Li.

11 recordsLinked to original sources

PubMed2006

Enhancement of hydrolysis and acidification of solid organic waste by a rotational drum fermentation system with methanogenic leachate recirculation.

A cascade process of a rotational drum fermentation system with leachate recirculation from a methanogenic to the acidogenic reactor was constructed to enhance the hydrolysis and acidification of solid organic waste. Using fresh soybean meal as substrates, two process configurations, Cascade process 1 and 2, without and with leachate recirculation, respectively were employed to perform the experimental estimation under mesophilic condition and a total HRT of 20 days. An apparent first-order hydrolysis rate constant of 9.0 x 10(-3)/d for Cascade process 1 at pH 4.5-4.6, and 15.8 x 10(-3)/d for Cascade process 2 at pH 4.6-5.2 were obtained. The apparent VS degradation ratios ranged from 16.5% to 21.1% and total VA (as acetic acid) from 14.5 to 16.7 g/L. Occupying ratios for ionized VA decreased from 40.5% to 35.3% for Cascade process 1 and increased to 68.5% for Cascade process 2. However, occupying ratios of acetic acid decreased from 96.1% to 94.3% for Cascade process 1 and to 72.6% for Cascade process 2, whereas propionic acid and butyric acid ratios increased in acidogenesis of Cascade process 2. The leachate recirculation promoted hydrolysis of substrate in Cascade process 2, where apparent hydrolysis rate constant and VS degradation ratio were higher than that of Cascade process 1.

Acetic Acid↗

PubMed2006

Enhanced cocaine self-administration in adult rats with adolescent isolation experience.

It is widely accepted that early environmental influences may affect the behavior of adult animals and their responses to psychotropic drugs. Rearing animals in isolation is a relevant paradigm for studying early life stress and for understanding the development of certain neurological and psychiatric diseases. The present study evaluated the effect of adolescent isolation on intravenous cocaine self-administration in adult rats. Male Sprague-Dawley rats were raised from postnatal day 22 to 55 either alone (isolated) or in groups of four per cage (grouped). Then, rats were trained for cocaine self-administration. Our results showed that both isolated and grouped rats acquired stable cocaine self-administration during 5 days of self-administration training. Numbers of both lever presses and cocaine infusions in isolated rats were significantly more than those in grouped rats. Especially, numbers of incorrect lever presses in isolated rats were significantly more than those in grouped rats. In addition, the intervals of inter-reinforcement for cocaine in isolated rats were significantly shorter as compared with grouped rats. These results indicate that rats with adolescent isolation experience have enhanced cocaine self-administration behavior.

Animals↗

PubMed2006

Model estimation and measurement of ammonia emission from naturally ventilated dairy cattle buildings with slatted floor designs.

Laboratory experiments were carried out in a wind tunnel with a model of a slurry pit to investigate the characteristics of ammonia emission from dairy cattle buildings with slatted floor designs. Ammonia emission at different temperatures and air velocities over the floor surface above the slurry pit was measured with uniform feces spreading and urine sprinkling on the surface daily. The data were used to improve a model for estimation of ammonia emission from dairy cattle buildings. Estimates from the updated emission model were compared with measured data from five naturally ventilated dairy cattle buildings. The overall measured ammonia emission rates were in the range of 11-88 g per cow per day at air temperatures of 2.3-22.4 degrees C. Ammonia emission rates estimated by the model were in the range of 19-107 g per cow per day for the surveyed buildings. The average ammonia emission estimated by the model was 11% higher than the mean measured value. The results show that predicted emission patterns generally agree with the measured one, but the prediction has less variation. The model performance may be improved if the influence of animal activity and management strategy on ammonia emission could be estimated and more reliable data of air velocities of the buildings could be obtained.

Air Pollutants↗

PubMed2005

Improving acidogenic performance in anaerobic degradation of solid organic waste using a rotational drum fermentation system.

The effects of leachate from a methanogenic process on acidogenic performance of a solid recycle (SR) process by a rotational drum fermentation (RDF) system were evaluated under mesophilic condition and a hydraulic retention time (HRT) of 20 days. Two SR process configurations, SR1 and SR2, were evaluated, using fresh soybean meal or Okara as substrates. An apparent first-order hydrolysis rate constant of 5.0 x 10(-3)/d for SR1 at pH values of 4.4 and 14.4 x 10(-3)/d for SR2 at pH of 5.0, were obtained. The apparent volatile solids (VS) degradation ratio ranged from 9.6% to 19.4% and total volatile acid (as acetic acid) from 10.8 to 14.9 g/L. Occupying ratios for ionized volatile acid (VA) increased from 30.6% to 63.4% after recycling the leachate to process. However, occupying ratios of acetic acid decreased from 93.3% to 42.0% whereas propionic acid and butyric acid ratios increased in SR2. Integrating the VA production with the hydrolysis rate constants, it is clear that the recirculation of leachate considerably enhanced acidogenic performance of solid recycle process.

Bacteria, Anaerobic↗

PubMed2005

Tradeoff between mixing and transport for electroosmotic flow in heterogeneous microchannels with nonuniform surface potentials.

Electroosmotic flow (EOF) is a phenomenon associated with the movement of an aqueous solution induced by the application of an electric field in microchannels. The characteristics of EOF depend on the nature of the surface potential, i.e., whether it is uniform or nonuniform. In this paper, a lattice Boltzmann model (LBM) combined with the Poisson-Boltzmann equation is used to simulate flow field in a rectangular microchannel with nonuniform (step change) surface potentials. The simulation results indicate that local circulations can occur near a heterogeneous region with nonuniform surface potentials, in agreement with those by other authors. Largest circulations, which imply a highest mixing efficiency due to convection and short-range diffusion, were found when the average surface potential is zero, regardless of whether the distribution of the heterogeneous patches is symmetric or asymmetric. In this work, we have illustrated that there is a trade-off between the mixing and liquid transport in EOF microfluidics. One should not simply focus on mixing and neglect liquid transport, as performed in the literature. Excellent mixing could lead to a poor transport of electroosmotic flow in microchannels.

Journal Article↗

PubMed2004

Wettability interpretation of oxygen plasma modified poly(methyl methacrylate).

Poly(methyl methacrylate) (PMMA) has been modified via a dc pulsed oxygen plasma for different treatment times. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), optical profilometer, zeta potential, and advancing contact angle measurements. The measured advancing contact angles of water decreased considerably as a function of discharge. Several oxygen-based functionalities (carbonyl, carboxyl, carbonate, etc.) were detected by XPS, while zeta potential measurements confirmed an increase in negative charge for the treated PMMA surface. Evaluating the correlation between the concentration of polar chemical species and zeta potential, we found that increase in surface hydrophilicity results from the coeffect due to incorporation of oxygen functional groups and creation of charge states. The electrical double layer (EDL) effect was also considered in contact angle interpretation by introducing an additional surface tension term into Young's equation. We also found that EDL contribution to the solid-liquid interfacial tension is negligible and can be safely ignored for the systems considered here.

Molecular Structure↗

PubMed2004

Mean-field free-energy approach to the lattice Boltzmann method for liquid-vapor and solid-fluid interfaces.

We present a lattice Boltzmann method (LBM) using a mean-field representation of the free energy for fluid systems. This free-energy approach provides more realistic contact angles and fluid density profiles near the vicinity of an impenetrable wall which cannot be easily obtained by other LBM schemes. Our method was tested against various criteria and the results are in good agreement with those from thermodynamics and molecular dynamics considerations. This mean-field approach to LBM can have an important implication on studies where the solid-fluid interactions are crucial to fluidic behaviors.

Journal Article↗

PubMed2004

Electrokinetic microfluidic phenomena by a lattice Boltzmann model using a modified Poisson-Boltzmann equation with an excluded volume effect.

A lattice Boltzmann model (LBM) for electrokinetic microfluidics recently proposed by us [J. Colloid Interface Sci. 263, 144 (2003); Langmuir 19, 3041 (2003)] is employed by consideration of a modified Poisson-Boltzmann equation including an excluded volume effect. In our study, pressure is considered as the only external force for liquid flow. As commonly used, the Poisson-Boltzmann equation assumes only point charge, the predicted microfluidic phenomena of KCl and LiCl electrolyte solutions are theoretically the same; these phenomena, however, have been found to be experimentally different. Our LBM in conjunction with the modified Poisson-Boltzmann equation are capable of explaining this discrepancy and the results are in good agreement with recent experimental data for KCl and LiCl electrolyte solutions in pressure-driven microchannel flow, suggesting that our proposed LBM can be employed to predict the more complex microfluidic systems that might be problematic using conventional methods and electrokinetic models.

Journal Article↗

PubMed2004

SNAP-25 in hippocampal CA1 region is involved in memory consolidation.

As a synaptosomal protein, SNAP-25 plays a role in a number of neuronal functions including axonal growth, dendrite formation, fusion of synaptic vesicles with membrane and the expression of long-term potentiation (LTP) in the hippocampus. Using a learning/memory behavior screening, we identified SNAP-25 as one of the differentially expressed genes in the hippocampus upon behavioral training. The inhibition of SNAP-25 with intracerebroventricular antisense oligonucleotide caused a deficit in long- but not short-term memory for step-down inhibitory avoidance. Intra-CA1 infusion of the SNAP-25 antisense oligonucleotide impaired long-term contextual fear memory and spatial memory and interfered with the LTP of synaptic transmission in the CA1 region. The inhibitory effect on LTP was not mediated by a pre-synaptic mechanism because paired pulse facilitation of synaptic transmission was not affected after administration of the antisense oligonucleotide. Together, the results suggest that SNAP-25 in the CA1 region is involved in memory consolidation.

Animals↗

PubMed2003

Lattice Boltzmann model of microfluidics in the presence of external forces.

We present here a lattice Boltzmann model in the presence of external force fields to describe electrokinetic microfluidic phenomena and consider pressure as the only external force to drive liquid flow. Our results from a 9-bit square lattice Boltzmann model are in good agreement with recent experimental data in a pressure-driven microchannel flow that could not be fully described by electrokinetic theory. The differences between the predicted and the experimental Reynolds numbers from pressure gradients are well within 5%. Results suggest that the lattice Boltzmann model described here is an effective computational tool for predicting the more complex microfluidic systems that might be problematic using conventional methods.

Journal Article↗

PubMed2003

Discrete Boltzmann equation for microfluidics.

We propose a discrete Boltzmann model for microfluidics based on the Boltzmann equation with external forces using a single relaxation time collision model. Considering the electrostatic interactions in microfluidics systems, we introduce an equilibrium distribution function that differs from the Maxwell-Boltzmann distribution by an exponential factor to represent the action of an external force field. A statistical mechanical approach is applied to derive the equivalent external acceleration force exerting on the lattice particles based on a mean-field approximation, resulting from the electro-static potential energy and intermolecular potential energy between fluid-fluid and fluid-substrate interactions.

Journal Article↗