scholarly journals Seasonal change in growth rate, carrageenan yield and quality from the red alga (Kappaphycus striatus) cultivated in Cam Ranh bay

2021 ◽  
Vol 18 (4) ◽  
pp. 763-771
Author(s):  
Le Dinh Hung ◽  
Le Thi Hoa

The red alga Kappaphycus striatus was cultivated at Camranh Bay, KhanhHoa, Vietnam. For a 30 day cultivation period, the alga showed the higher growth rate (4.1 - 5.8 % day-1) from October 2014 to April 2015 and in September 2015, while the lower growth rate (2.5 - 3.1 % day-1) was found from May to August 2015. The carrageenan quality was done for a 60-day cultivation period, the carrageenan yield and gel strength showed little variation with the higher values (28.1 - 28.7 % and 855 - 935 g cm-2, respectively) obtained from November 2014 to March 2015 and lower ones (25.1 - 26.7 % and 555 - 758 g cm-2, respectively) from April to September 2015. The data on moisture content of alga (33.5 - 36.8 %), clean anhydrous algal/salt ratio (0.92 - 1.07), and carrageenan yield obtained in this study fulfilled those of standards for carrageenophytes. This study shows that the red alga K. striatus can be grown in the tropical waters of the Camranh Bay during the northeast monsoon and a part of the southwest monsoon as a source of materials for carrageenan production.

2002 ◽  
Vol 74 (1) ◽  
pp. 135-144 ◽  
Author(s):  
A. Belenguer ◽  
J. Balcells ◽  
M. Fondevila ◽  
C. Torre

AbstractThe present study compares estimates of caecotrophes production from urinary purine derivatives (PD) excretion with that from preventing caecotrophy by using a neck collar. A total of 64 New Zealand growing male rabbits were used to study the effect of diet composition on caecotrophes production. Diets were formulated using two sources of structural carbohydrates (fibre): alfalfa hay (AH) and sugar-beet pulp (SBP), mixed at two constant proportions, (0·75: 0·25) AH diets and (0·25: 0·75) SBP diets. Both diets included either barley or maize grain at two fibre: grain ratios (F/G, 80: 20 and 45: 55). Diets were given ad libitum. Growth rate, dry matter intake and digestibility were not modified by the grain source, although high F/G diets resulted in a lower growth rate (19·8 v. 26·4 g/day; P < 0·001). Between fibre sources, dry-matter intake and growth were higher in AH than in SBP diets (122·5 and 25·6 v. 101·6 and 20·4 g/day, respectively, P < 0·001 and P < 0·01). Rabbits given high F/G ratio and AH diets excreted more caecotrophes than those given low F/G ratio and SBP diets (19·5 and 20·9 v. 16·3 and 14·85 g/day, respectively). Microbial-N recycling through the caecotrophy process was higher when considering data from PD excretion (1·33 g/d) than when estimated by preventing caecotrophy (0·72 g/day).


2016 ◽  
Vol 30 (06) ◽  
pp. 1650059
Author(s):  
Jingjing Gao ◽  
Mingwen Chen ◽  
Zidong Wang

The convection of ambient flow field has a significant influence on the pattern formation of growing particles. In this paper, we investigate the shape evolution of particles growing in supersaturated solution affected by straining flows. By using the multiple variable asymptotic expansion method, we obtain the asymptotic solution. The solution indicates that the interface microstructure is greatly affected by the straining flows. The flow results in a higher growth rate in the surface where it is incoming and a lower growth rate where it is outgoing. Besides, the flow also has effects on the concentration distribution.


Weed Science ◽  
1983 ◽  
Vol 31 (4) ◽  
pp. 438-444 ◽  
Author(s):  
William H. Ahrens ◽  
E. W. Stoller

Triazine-susceptible (S) and -resistant (R) biotypes of smooth pigweed (Amaranthus hybridusL.) were grown in the field under competitive conditions at varying initial proportions of S and R plants. R plants were less competitive than S plants as measured by accumulation of total above-ground dry weight and seed dry weight. S and R plants were also grown in the field under non-competitive conditions at 100, 40, and 10% light. Growth rate at 10% light did not differ between S and R plants. At the two higher light intensities, dry-matter accumulation 11 weeks after seeding was about 40% less in the R plants. At 100% light, relative growth rate and net assimilation rate were lower in the R plants by about 3.5 and 19%, respectively. The light- and CO2-saturated rates of CO2fixation in intact leaves of glasshouse-grown R plants were 20% less than those in S plants. An apparent 10 and 20% greater number of chlorophyll molecules per photosystem II reaction center in R plants (as compared with S plants) grown in the field at 40 and 100% light, respectively, did not explain differences between the S and R biotypes in photo synthetic capacity. The S and R plants did not differ in specific leaf weight or chlorophyll content on a leaf-area basis. Lower growth rate of R plants may be responsible for inferior competitive ability of R biotypes and could be the result of an impaired photosynthetic capacity.


2013 ◽  
Vol 79 (13) ◽  
pp. 4145-4148 ◽  
Author(s):  
Takanori Awata ◽  
Mamoru Oshiki ◽  
Tomonori Kindaichi ◽  
Noriatsu Ozaki ◽  
Akiyoshi Ohashi ◽  
...  

ABSTRACTThe phylogenetic affiliation and physiological characteristics (e.g.,Ksand maximum specific growth rate [μmax]) of an anaerobic ammonium oxidation (anammox) bacterium, “CandidatusScalindua sp.,” enriched from the marine sediment of Hiroshima Bay, Japan, were investigated. “CandidatusScalindua sp.” exhibits higher affinity for nitrite and a lower growth rate and yield than the known anammox species.


2006 ◽  
Vol 73 (2) ◽  
pp. 432-441 ◽  
Author(s):  
Olle Rengby ◽  
Elias S. J. Arnér

ABSTRACT Release factor 2 (RF2), encoded by the prfB gene in Escherichia coli, catalyzes translational termination at UGA and UAA codons. Termination at UGA competes with selenocysteine (Sec) incorporation at Sec-dedicated UGA codons, and RF2 thereby counteracts expression of selenoproteins. prfB is an essential gene in E. coli and can therefore not be removed in order to increase yield of recombinant selenoproteins. We therefore constructed an E. coli strain with the endogenous chromosomal promoter of prfB replaced with the titratable PBAD promoter. Knockdown of prfB expression gave a bacteriostatic effect, while two- to sevenfold overexpression of RF2 resulted in a slightly lowered growth rate in late exponential phase. In a turbidostatic fermentor system the simultaneous impact of prfB knockdown on growth and recombinant selenoprotein expression was subsequently studied, using production of mammalian thioredoxin reductase as model system. This showed that lowering the levels of RF2 correlated directly with increasing Sec incorporation specificity, while also affecting total selenoprotein yield concomitant with a lower growth rate. This study thus demonstrates that expression of prfB can be titrated through targeted exchange of the native promoter with a PBAD-promoter and that knockdown of RF2 can result in almost full efficiency of Sec incorporation at the cost of lower total selenoprotein yield.


1974 ◽  
Vol 13 (3) ◽  
pp. 231-244 ◽  
Author(s):  
A.R. Kemal ◽  
Talat Alauddin

It is a well-known fact that capital is scarce in most of the developing countries and thus some of the production factors, such as labour, remain unemployed, leading to a lower growth rate of G.N.P. than would be possible under full employment. Additions to the stock of capital not only increase the rate of growth but also provide new job opportunities. However, in many developing countries, capital is utilised less than one-third of the time [10,p.38], The underutilization of capital obviously shrinks the growth rate of less deve¬loped countries still further. Capacity underutilization discourages technological progress which leads to an inefficient industrial structure. This presents us with a paradox: if capital is scarce in developing countries, why is it underutilized? A number of hypotheses have been advanced to explain this paradox. Some of these hypotheses relate to oligopolistic structure of the market, deficient demand, non-availability of complementary factors of production (such as skilled labour), imported inputs and government licensing policies. Moreover, when aid is available for specific projects, there is a tendency to build up addi¬tional capacity because the recipient countries prefer some aid to no-aid. However, very little has been done so far in building a theoretical framework which could be used in empirical analysis to throw light on the possible causes of capacity underutilization. Marris's theoretical framework [4] and Winston's empirical investigation of capacity utilization in Pakistan [10] are exceptions.


Author(s):  
Abhijit Paul ◽  
Samrat Chatterjee ◽  
Nandadulal Bairagi

The pandemic disease Covid-19 caused by SARS-COV-2, which emerged from Wuhan, China, has established itself as the most devastating disease in the history of infectious disease, affecting 216 countries/territories across the world. Different countries have developed and adopted various policies to contain this epidemic and the most common were the social distancing and lockdown. Though some countries have come out of this pandemic, the infection is still increasing and remains very serious in the rest of the world. Even when the disease is not under control, many countries have withdrawn the lockdown and going through the phase-wise unlocking process, causing a further increment in the infection rate. In such a scenario, the role of the undetected class of infected individuals has become very crucial. The present study is an attempt to understand and estimate the possible epidemic burden during the unlock phase in the presence of an undetected class. We proposed a modified SEIR model and dissected the epidemiological status of different countries with the available data. With the initial establishment of the model with the epidemic data of four countries, which have already attained the epidemic peak, the study focused more on countries like India and the USA, where the epidemic curve is still growing, but the unlock process has started. As a straightforward result, we noticed a significant increase in the undetected and detected infected cases under the ongoing unlock phase. Under such conditions, our recalibration exercise showed that an increase in the testing could revert the existing growth rate of the infected cases to the lower growth rate of the lockdown period. Our present study emphasizes on the implementation of 3T principles, trace, test, and treat, to contain the epidemic. The significance of large scale testing in controlling the epidemic is true for both India and the USA though they have different socio-economic conditions. The use of repurposing drugs may further decrease the infected cases and help the disease controlling process. We believe our proposed strategy obtained through a mathematical model will help to make a better policy for the unlock phase.


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