Abiotic formation of bioorganic compounds in space--preliminary experiments on ground and future exobiology experiments in space.

Simulation experiments on ground have shown that "amino acid precursors", which give amino acids after acid-hydrolysis, can be formed when an ice mixture simulating ice mantles of interstellar dust particles (lSDs) is irradiated with high energy particles or UV light. It is strongly suggested that such bioorganic compounds were delivered by comets for the first biosphere on the Earth. It is of great interest to confirm this hypothesis in actual space conditions, such as in an exposed facility of JEM. Fundamental designs for such exobiology experiments in earth orbit (EEEO) will be discussed.     

X-ray spectra from laser targets in experiments on the SOKOL-P facility

X-ray spectra from targets irradiated by picosecond laser pulses with intensities of 3 × 10¹⁷-10¹⁸ W/cm² have been studied experimentally on the SOKOL-P facility. Both massive metal targets and multilayer targets with a buried emitting layer have been examined. The measurement results are interpreted by using numerical simulations and theoretical analysis. Experimental data on the X-ray continuum in the photon energy range of 0.8–6 keV and the line spectra of hydrogen-and helium-like aluminum ions are found to agree satis-factorily with numerical results.     

Establishing laboratory cultures and performing ecological and evolutionary experiments with the emerging model species Chironomus riparius

Chironomus riparius is a well‐established model organism in various fields such as ecotoxicology and ecology, and therefore, environmental preferences, ecological interactions and metabolic traits are well‐studied. With the recent publication of a high‐quality draft genome, as well as different population genetic parameters such as mutation and recombination rate, the species can be used as an alternative to the Drosophila models in experimental population genomics or molecular ecology. To facilitate access to this promising experimental model species for a wider range of researchers, we describe experimental methods to first create and sustain long‐term cultures of C. riparius and then use them to perform repeatable and comparable experiments for various research questions.     

On the optimum distribution of enzyme feed in a cascade of CSTR's performing an enzyme-catalyzed reaction with deactivation

A search for the optimum fractional distribution of an enzyme-rich stream to the various reactors of a cascade of CSTR's was implemented. A theoretical analysis, laid out in dimensionless form and based on the assumptions that the system is operated under steady state conditions, the enzyme undergoes first order deactivation, and the reaction catalyzed by the enzyme follows Michaelis-Menten kinetics, is reported. The objective function utilised is the minimisation of the overall volume of the cascade, and analytical expressions are obtained for the concentration of active enzyme and substrate in the outlet stream from each reactor. It is found that the best option is to add the whole enzyme-rich stream to the first reactor in the cascade irrespective of the operating and kinetic parameters of the system.     

Dual tail catheters for infusion and sampling in rats as an efficient platform for metabolic experiments

The authors present a technique for establishing a virtually stress-free dual-catheter system in rats, allowing researchers to conduct extended, complex experimental procedures involving the simultaneous infusion of multiple compounds and frequent collection of blood samples.     

The dynamics of outbreaks: Further simulation experiments with the western tent caterpillar

A stochastic model of western tent-caterpillar populations on southern Vancouver Island was used to assess conditions leading to outbreaks. Three qualitatively different populations-declining, minimal, and recovering-were exposed to six-year climatic sequences incorporating various combinations of good, bad, and mediocre spring weather. Starting populations were either distributed randomly or concentrated in and around small-, medium-, or large refuges. The results showed that virtually any type of population could temporarily increase in numbers during two highly favorable springs. Only a very few vigorous populations, however, could sustain the momentum required to surge to outbreak proportions. No low-quality population could do so. And even vigorous populations could not achieve outbreak status unless they were initially concentrated in a sufficiently large refuge that was close enough to potentially suitable habitats to permit rapid immigration into such places as soon as their local climates improved. The concept of “climatic release” of insect populations is discussed in the light of these findings. The results demonstrate that climatic release is inextricably linked with a population's qualitative profile and spatial distribution.     

On performing experimental studies on transient states of continuous-flow methanogenic reactors

One approach to exploring the behavior of microbial cultures during transient conditions of unbalanced growth is to experimentally observe continuous-flow biological reactors which have been subjected to perturbations in the influent flowrate and/or concentration of growth-limiting substrate. Proper interpretation of such experiments requires that appropriate account be taken of reaction stoichiometry, the distribution and abundance of microbial populations within the reactor, and the nonideality of mixing and flow distribution in the reactor. These aspects of proper experimental design are particularly critical when the system of interest involves methanogenic consortia and is not a completely-mixed, suspended-growth reactor.     

Integration of stochastic simulation with multivariate analysis: Short‐term facility fit prediction

This article describes a decision‐support tool to help pinpoint the potential root causes of sub‐optimal short‐term facility fit issues in biopharmaceutical facilities. This was achieved by creating a tool that integrated stochastic simulation with advanced multivariate statistical analysis. Process fluctuations in product titers in cell culture, step yields, and chromatography eluate volumes were mimicked using Monte Carlo simulation data derived using a stochastic discrete‐event simulation model. The resulting stochastic datasets, with the computed consequences on key metrics such as product mass loss and cost of goods, were examined using advanced multivariate statistical techniques. Principal component analysis combined with clustering algorithms was used to analyze the complex datasets from complete industrial batch processes for biopharmaceuticals. The challenge of visualizing the multidimensional nature of the dataset was addressed using hierarchical and k‐means clustering as well as stacked parallel co‐ordinate plots to help identify process fingerprints and characteristics of clusters leading to sub‐optimal facility fit issues. Industrially‐relevant case studies are presented that focus on technology transfer challenges for therapeutic antibodies moving from early phase to late phase clinical trials. The case study details how sub‐optimal facility fit can be alleviated by allocating alternative product pool tanks. The impact of this operational change is then assessed by reviewing an updated process fingerprint. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29: 368–377, 2013     

Systematic simulation of a tubular recycle reactor on the basis of pilot plant experiments

Systematic simulation may decisively help in development and optimization of bioprocesses. By applying simulation techniques, optimal use can be made of experimental data, decreasing development costs and increasing the accuracy in predicting the behavior of an industrial scale plant.The procedure of the dialogue between simulation and experimental efforts will be exemplified in a case study. Alcoholic fermentation of glucose by zymomonas mobilis bacteria in a gasified tubular recycle reactor was studied first by systematic simulation, using a computer model based solely on literature data. On the base of the results of this simulation, a 0.013 m³ pilot plant reactor was constructed. The pilot plant experiments, too, were based on the results of the systematic simulation.Simulated and experimental data were well in agreement. The pilot plant experiments reiterated the trends and limits of the process as shown by the simulation results. Data from the pilot plant runs were then used to improve the simulation model. This improved model was subsequently used to simulate the performances of an industrial scale plant. The results of this simulation are presented. They show that the alcohol fermentation in a tubular recycle reactor is potentially advantageous to other reactor configurations, especially to continuous stirred tanks.List of Symbols CPFR Continous plug flow reactor - CST R Continous stirred tank reactor - CTR Continous tubular reactor - FMC Fermentation micro computer - P kg/m³ Product concentration - S kg/m³ Glucose concentration - S _o kg/m³ Glucose concentration in the feed - X kg/m³ Biomass concentration - z Cell damage     

On the design of closed recapture experiments

We propose a method to plan the number of occasions of recapture experiments for population size estimation. We do so by fixing the smallest number of capture occasions so that the expected length of the profile confidence interval is less than or equal to a fixed threshold. In some cases, we solve the optimization problem in closed form. For more complex models we use numerical optimization. We detail models assuming homogeneous, time‐varying, subject‐specific capture probabilities, behavioral response to capture, and combining behavioral response with subject‐specific effects. The principle we propose can be extended to plan any other model specification. We formally show the validity of the approach by proving distributional convergence. We illustrate with simulations and challenging examples in epidemiology and ecology. We report that in many cases adding as few as two sampling occasions may substantially reduce the length of confidence intervals.     

对微生物工程类虚拟仿真实验建设与共享应用的思考

微生物工程是一门实践性和应用性较强的课程.让学生走进企业的生产线进行实践性学习是必不可少的教学环节.实习资源不足一直是限制微生物工程课程开展高水平实习教学的瓶颈.利用信息技术搭建的虚拟化生产线不但可以使学生从中学习复杂的生产系统中的理论性知识,还能进行更深层次的虚拟操作,从而促进学生实践能力和创新能力的形成.为了更好地...     

Postembryonic development of anurans in ponds littered with metal-containing refuse (simulation experiments)

The effect of pond pollution with lead- and iron-containing alloys on the morphogenesis of brown frog (Rana temporaria), moor frog (Rana arvalis), and common toad (Bufo bufo) tadpoles was studied in simulation experiments. Observations showed that metal particles were ingested by tadpoles and produced a significant effect on their body dimensions. Tadpoles developing in water polluted with iron had an increased body size, while lead pollution resulted in retarded growth of tadpoles, and they were significantly smaller than in the control group. However, water pollution with metal alloys had no effect on the proportionality of their development.