scholarly journals Factors Affecting Recombinant Frequency in Protoplast Fusions of Streptomyces coelicolor

1979 ◽  
Vol 111 (1) ◽  
pp. 137-143 ◽  
Author(s):  
D. A. Hopwood ◽  
H. M. Wright
2020 ◽  
Vol 1 (40) ◽  
pp. 131-141
Author(s):  
Tuan Pham Nguyen ◽  
Lam Hong Bang

Prodigiosin is a red pigment and widely applied as antimicrobial, antifungal, anti-malarial, anti-cancer, ,...Prodigiosin is isolated from bacteria, such as Serratia marcescens, Hahella chejuensis, Vibrio psychroerythrus and Streptomyces coelicolor,. . . S. marcescens is the major producer of prodigiosin. The production of prodigiosin has been shown to be influenced by many factors, such as species type and environmental factors, including media composition, temperature, pH and incubation time,... This study was conducted to analyze the effect of various factors on prodigiosin production process of S. marcescens SR3 by submerged fermentation method. Prodigiosin content was determined by the spectrophotometer method. The results showed thatS. marcescens SR3 could produce prodigiosin in LB medium, initial bacterial volume (7%, v/v), carbon source (lactose 1 g/L), nitrogen source (yeast extract 5 g/L), pH = 8, fermentation time (96 hours), and prodigiosin content reached 527.28 Unit/cell. The results of the study showed that S. marcescens SR3 bacteria is a potential source of prodigiosin for research and applications.


Author(s):  
F. A. Heckman ◽  
E. Redman ◽  
J.E. Connolly

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.


Author(s):  
Christine M. Dannels ◽  
Christopher Viney

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.


1990 ◽  
Vol 54 (11) ◽  
pp. 638-643 ◽  
Author(s):  
PC Damiano ◽  
ER Brown ◽  
JD Johnson ◽  
JP Scheetz

1976 ◽  
Vol 7 (4) ◽  
pp. 207-219 ◽  
Author(s):  
Constance P. DesRoches

A statistical review provides analysis of four years of speech therapy services of a suburban school system which can be used for comparison with other school system programs. Included are data on the percentages of the school population enrolled in therapy, the categories of disabilities and the number of children in each category, the sex and grade-level distribution of those in therapy, and shifts in case-load selection. Factors affecting changes in case-load profiles are identified and discussed.


2019 ◽  
Vol 62 (5) ◽  
pp. 1243-1257 ◽  
Author(s):  
Peggy Pik Ki Mok ◽  
Holly Sze Ho Fung ◽  
Vivian Guo Li

Purpose Previous studies showed early production precedes late perception in Cantonese tone acquisition, contrary to the general principle that perception precedes production in child language. How tone production and perception are linked in 1st language acquisition remains largely unknown. Our study revisited the acquisition of tone in Cantonese-speaking children, exploring the possible link between production and perception in 1st language acquisition. Method One hundred eleven Cantonese-speaking children aged between 2;0 and 6;0 (years;months) and 10 adolescent reference speakers participated in tone production and perception experiments. Production materials with 30 monosyllabic words were transcribed in filtered and unfiltered conditions by 2 native judges. Perception accuracy was based on a 2-alternative forced-choice task with pictures covering all possible tone pair contrasts. Results Children's accuracy of production and perception of all the 6 Cantonese tones was still not adultlike by age 6;0. Both production and perception accuracies matured with age. A weak positive link was found between the 2 accuracies. Mother's native language contributed to children's production accuracy. Conclusions Our findings show that production and perception abilities are associated in tone acquisition. Further study is needed to explore factors affecting production accuracy in children. Supplemental Material https://doi.org/10.23641/asha.7960826


2000 ◽  
Vol 27 (12) ◽  
pp. 1030-1033 ◽  
Author(s):  
M. Patel ◽  
H. Tawfik ◽  
Y. Myint ◽  
D. Brocklehurst ◽  
J. W. Nicholson

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