Average Micro Research Articles

Influence of culture passages on growth kinetics and adenovirus vector production for gene therapy in monolayer and suspension cultures of HEK 293 cells.

To characterize the changes in cell growth rate and adenovirus vector (AdV) production capability of 293 cells during culture passages, 293 cells obtained at the 31st culture passage from ATCC (293M #31) were maintained as a monolayer culture and 293 cells obtained at an unknown culture passage from Invitrogen (293S) were maintained as suspension culture. In monolayer culture, the specific growth rate (micro) of 293M cells increased rapidly with culture passage up to passage 65 and thereafter became saturated. The micro of 293M passage 43 (#43) was 0.29 day(-1), while the average micro of 293M from #66 to #86 was 0.74+/-0.01 day(-1) (average +/- standard deviation). It was also noted that the cells became smaller in size during early culture passages. AdV production was also influenced by the number of culture passages. The AdV titer in the culture of 293M #66 was ca. tenfold higher than that of 293M #44, resulting from both a higher cell concentration and a higher AdV titer per cell at #66. In contrast, the micro, cell size, and AdV production of 293S cells in suspension culture did not change significantly as the culture passage number increased up to #40. Taken together, the culture passage influenced cell growth and AdV production of 293M cells in monolayer culture, but not those of 293S cells in suspension culture.

The synthesis: Structure relationship in the ZnO-Cr2O3 system

In this work the development of the spinel phase in the ZnO-Cr2O3 system was discussed from the viewpoint of the synthesis-structure relationship. The nanostructure evolution in particles obtained either via solution-based (spray pyrolysis) or solid-state (mechanical activation) synthesis procedures were investigated by XRD analysis. A detailed structural analysis of the spinel phase lattice parameters, average primary crystallite sizes and micro strains were performed in accordance with a procedure based on the Koalariet-Xfit program. Due to the importance of spinel-phase cat ion distribution for chemical and physical properties, a study of the site occupation factors, i.e. changes in the stoichiometric, of ZnCr2O4 spinals was undertaken. The calculation based on atomistic methods for the description of both perfect and defect spinel ZnCr2O4 crystal lattices has been applied and the presence of individual structural defects was determined.

STRUCTURAL CHARACTERIZATION OF CO-PRECIPITATED Cd1-xZnxS:Cu CRYSTALS

Structural characterization of Cd 1-x Zn x S : Cu solid solutions were carried out with 0≤x≤1. XRD studies have revealed that the compounds are polycrystalline in nature having either Hexagonal (wurtzite) or Cubic (Zincblende) structure irrespective of their composition. Also the compounds have shown the most preferred reflections due to the plane [101] of CdS(H) and [111] of ZnS(C) in addition to other prominent reflections. The various structural parameters such as lattice constant, average internal stress, micro strain, dislocaion density, grain size, and preferred orientation were correlated with the composition. The lattice constant decreased linearly with the increase in Zn concentration. The sign of internal stress indicated elongational and compressional natures corresponding to hexagonal and cubic phases of CdS respectively. The variation of micro strain appeared to be conjugate when compared to grain size variation, and the variation of dislocation density with the composition showed a higher dislocation density till x=0.4 and then decreased till x=0.8 and then increased. The degree of preferred orientation in mixed Cd 1-x Zn x S : Cu crystals as observed by the maximum peak intensity of CdS(H) and ZnS(C) reflection showed that the degree of preferred orientation remained almost constant till x=0.6 and then increased. The results were explained on the basis of different phases of the compound and the defects related to Zn atoms.

Decomposition and quantitative analysis of clinical electromyographic signals

Procedures for the quantitative analysis of clinical electromyographic (EMG) signals detected simultaneously using selective or micro and non-selective or macro electrodes are presented. The procedures first involve the decomposition of the micro signals and then the quantitative analysis of the resulting motor unit action potential trains (MUAPTs) in conjunction with the associated macro signal. The decomposition procedures consist of a series of algorithms that are successively and iteratively applied to resolve a composite micro EMG signal into its constituent MUAPTs. The algorithms involve the detection of motor unit action potentials (MUAPs), MUAP clustering and supervised classification and they use shape and firing pattern information along with data dependent assignment criteria to obtain robust performance across a variety of EMG signals. The accuracy, extent and speed with which a set of 10 representative 20–30 s, concentric needle detected, micro signals could be decomposed are reported and discussed. The decomposition algorithms had a maximum and average error rate of 2.5% and 0.7%, respectively, on average assigned 88.7% of the detected MUAPs and took between 4 to 8 s. Quantitative analysis techniques involving average micro and macro MUAP shapes, the variability of micro MUAPs shapes and motor unit firing patterns are described and results obtained from analysis of the data set used to evaluate the decomposition algorithms are summarized and discussed.

Constitutive potential for ductile damaged material and void growth rate

In this paper a general formula for plastic potential including isotropic ductile damage has been presented on the basis of the thermodynamics for irreversible process and intemal variable theory. With this formula the mass conservation law is satisfied and it also contains a series of unknow coefficients which are the function of macro equivalent stress and the average micro equivalent stress and an unknown function which is the function of two generalized forces.

The Relationship of Drafting-Force Variability to Cotton Fiber Properties and Spinning Efficiency

Fifty-six bales of medium staple cotton were spun into 40s yarn to evaluate spinning performance. In a parallel effort, roving samples from each bale were tested on a single-end drafting tester that duplicates the Tru-Set drafting system used in spinning. Front-zone drafting force and force-vari ability measurements were related to fiber properties and spinning performance. Drafting-force variability correlated well with spinning. The correlation with spinning was improved by subtracting from drafting-force variance the weight variance caused by fiber randomization due to average micro naire fineness.