scholarly journals Biofuels from Micro-Organisms: Thermodynamic Considerations on the Role of Electrochemical Potential on Micro-Organisms Growth

2021 ◽  
Vol 11 (6) ◽  
pp. 2591
Author(s):  
Umberto Lucia ◽  
Giulia Grisolia
Keyword(s):  
Carbon Dioxide ◽  
Temperature Effect ◽  
Open Problem ◽  
Electric Potential ◽  
Present Model ◽  
Electrochemical Potential ◽  
Micro Organisms ◽  
Carbon Dioxide Mitigation ◽  
Do So

Biofuels from micro-organisms represents a possible response to the carbon dioxide mitigation. One open problem is to improve their productivity, in terms of biofuels production. To do so, an improvement of the present model of growth and production is required. However, this implies an understanding of the growth spontaneous conditions of the bacteria. In this paper, a thermodynamic approach is developed in order to highlight the fundamental role of the electrochemical potential in bacteria proliferation. Temperature effect on the biosystem behaviour has been pointed out. The results link together the electrochemical potential, the membrane electric potential, the pH gradient through the membrane, and the temperature, with the result of improving the thermodynamic approaches, usually introduced in this topic of research.

scholarly journals On the attempts to measure water (and other volatiles) directly at the surface of a comet

2017 ◽  
Vol 375 (2094) ◽  
pp. 20150385 ◽  
Author(s):  
I. P. Wright ◽  
S. Sheridan ◽  
G. H. Morgan ◽  
S. J. Barber ◽  
A. D. Morse
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Solar System ◽  
Space Mission ◽  
Daily Cycles ◽  
Surface Measurements ◽  
Comet 67P ◽  
Do So

The Ptolemy instrument on the Philae lander (of the Rosetta space mission) was able to make measurements of the major volatiles, water, carbon monoxide and carbon dioxide, directly at the surface of comet 67P/Churyumov–Gerasimenko. We give some background to the mission and highlight those instruments that have already given insights into the notion of water in comets, and which will continue to do so as more results are either acquired or more fully interpreted. On the basis of our results, we show how comets may in fact be heterogeneous over their surface, and how surface measurements can be used in a quest to comprehend the daily cycles of processes that affect the evolution of comets. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

Role of Models in Assessing New Agents for Caries Prevention-Non-Fluoride Systems: Reaction Paper

1995 ◽  
Vol 9 (3) ◽  
pp. 312-314
Author(s):  
R.G. Quivey ◽  
A.J. Smith
Keyword(s):  
Quantitative Methods ◽  
Model Systems ◽  
New Agents ◽  
Ph Values ◽  
Plaque Ph ◽  
Micro Organisms ◽  
Over Time ◽  
Do So

Several important issues have been raised concerning the need for consideration of alternatives to fluoride. The principle reason to do so has been the lack of comprehensive effectiveness of fluoride, which in turn reveals incomplete understanding of the caries process. Included among the topics required for clarification of caries initiation would be quantitative methods for relating plaque pH values to the formation of caries. Thus, methods for assessing the activity of anticaries agents over time would be of considerable assistance in monitoring the effects of these test compounds on bacteria. The use of recombinant oral micro-organisms containing genetic fusions, to provide information on the effects of agents on bacteria growing in model systems, is discussed as a possible means of obtaining relevant data in situ.

The Role of Micro-Organisms Other than Acinetobacter in Biological Phosphate Removal in Activated Sludge Processes

1983 ◽  
Vol 15 (3-4) ◽  
pp. 117-125 ◽  
Author(s):  
Karin E U Brodisch ◽  
Sylvia J Joyner
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Experimental Period ◽  
Phosphate Removal ◽  
Acinetobacter Species ◽  
Micro Organisms ◽  
Activated Sludge Processes ◽  
Plant Capacity ◽  
Do So

The composition of the microflora in the anaerobic, anoxic and aerated stages was determined by means of the Analytical Profile Index (API) system for three biological phosphate removal plants (a pilot plant (capacity 100 m3/d) and two laboratory scale units (capacity 24 ℓ/d)). The plants monitored differed with respect to anaerobic retention time and configuration, but all three were removing phosphate to concentrations less than 0.2 mg/ℓ as P during the experimental period. In contrast to findings by other investigators, bacteria of the genus Acinetobacter were present in minor proportions. Organisms of the genera Aeromonas and Pseudomonas constituted more than 50 % of the total aerobic microbial population. Depending on the length of the anaerobic retention time, 40 to 50 % of the bacteria were identified as Gram-positive. These findings suggest that Acinetobacter species may not be the only bacterium to remove phosphate from an activated sludge system, but that other groups of bacteria also do so under suitable environmental conditions.

The role of isocitrate lyase in the metabolism of algae

1966 ◽  
Vol 166 (1002) ◽  
pp. 11-29 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Soluble Fraction ◽  
Isocitrate Lyase ◽  
Tricarboxylic Acid Cycle ◽  
Glyoxylate Cycle ◽  
Tricarboxylic Acid ◽  
Chlamydomonas Reinhardii ◽  
The Glyoxylate Cycle ◽  
Do So

The incorporation of isotope from [2- 14 C]ethanol by cultures of the Brannon no. 1 strain of Chlorella vulgaris , growing on ethanol aerobically in the dark, was consistent with the operation of the tricarboxylic acid and glyoxylate cycles. Results obtained with [l- 14 C]acetate, added to similar cultures growing on glucose in the dark or on carbon dioxide in the light, indicated that the glyoxylate cycle did not function under these conditions. However, one of the key enzymes of this cycle, isocitrate lyase, was present in large amounts in extracts of this organism under all conditions of growth; in contrast, isocitrate lyase was inducibly formed by Chlamydomonas reinhardii prior to growth on acetate. No obvious dysfunction of the tricarboxylic acid cycle, which might necessitate the activity of isocitrate lyase during growth on other than C 2 -compounds, was detected in the Brannon no. 1 strain, nor were differences observed between the properties of the enzyme purified from cells grown on acetate and on glucose. But, whereas isocitrate lyase was wholly found in a soluble fraction of the organism after growth on glucose or on carbon dioxide, acetate-grown cells contained a major portion of their isocitrate lyase in a dense, particulate fraction. The Brannon no. 1 strain of Chlorella excreted labelled glycollate during growth in the dark on glucose in the presence of sodium [ 14 C]bicarbonate, but ceased to do so after transfer to acetate growth medium. The Pearsall’s strain of Chlorella , which does not form isocitrate lyase during growth on glucose, did not excrete labelled glycollate under these conditions. These results suggest that the Brannon no. 1 strain of Chlorella contained an active isocitrate lyase under all conditions of growth, but that this enzyme participates in the glyoxylate cycle only when it is incorporated into a particulate structure.

scholarly journals STUDIES ON THE DECOMPOSITION OF CELLULOSE BY MICRO-ORGANISMS

1947 ◽  
Vol 25c (6) ◽  
pp. 246-258 ◽  
Author(s):  
A. S. Perlin ◽  
M. Michaelis ◽  
W. D. McFarlane
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Crystalline Cellulose ◽  
Carbon Dioxide Content ◽  
Bacterial Polysaccharide ◽  
Cellulose Decomposition ◽  
Retarded Growth ◽  
Micro Organisms ◽  
Glucose Formation

The metabolism of an impure culture of an aerobic cellulose decomposing bacterium, Vibrio perimastix, was studied. The products of cellulose decomposition included carbon dioxide, a pigment resembling riboflavin, a bacterial polysaccharide, and traces of acid. Carbon dioxide was found to be essential for the decomposition of cellulose and could not be replaced by calcium carbonate. Increasing the carbon dioxide content of the air above 1.2% retarded growth on a glucose medium.Respiration studies were carried out using cellulose, glucose, and cellobiose as substrates, and the possible role of the latter two as intermediates in cellulose decomposition was investigated. Glucose was produced from cellulose when toluene was added to cultures during active decomposition; evidence is presented that a dialyzable factor produced by the bacteria is essential for glucose formation. Phosphorylation inhibitors prevented growth of the bacteria on cellulose, glucose, and cellobiose, inhibited respiration of active cellulose cultures, and retarded the production of glucose by toluene-treated cultures. Cellulose treated with alkali to increase the proportion of amorphous to crystalline cellulose was more rapidly decomposed than untreated cellulose.

Prospective Memory Development Across the Lifespan

2020 ◽  
Vol 25 (3) ◽  
pp. 162-173 ◽  
Author(s):  
Sascha Zuber ◽  
Matthias Kliegel
Keyword(s):  
Prospective Memory ◽  
Healthy Aging ◽  
Present Model ◽  
Current Knowledge ◽  
Well Being ◽  
The Elderly ◽  
Cognitive Factors ◽  
Everyday Functioning ◽  
Integrative Framework

Abstract. Prospective Memory (PM; i.e., the ability to remember to perform planned tasks) represents a key proxy of healthy aging, as it relates to older adults’ everyday functioning, autonomy, and personal well-being. The current review illustrates how PM performance develops across the lifespan and how multiple cognitive and non-cognitive factors influence this trajectory. Further, a new, integrative framework is presented, detailing how those processes interplay in retrieving and executing delayed intentions. Specifically, while most previous models have focused on memory processes, the present model focuses on the role of executive functioning in PM and its development across the lifespan. Finally, a practical outlook is presented, suggesting how the current knowledge can be applied in geriatrics and geropsychology to promote healthy aging by maintaining prospective abilities in the elderly.

A Re-Appraisal of the Role of Blood Coagulation and Platelets in the Generalized Shwartzman Phenomenon

1966 ◽  
Vol 15 (03/04) ◽  
pp. 519-538 ◽  
Author(s):  
J Levin ◽  
E Beck
Keyword(s):  
Blood Coagulation ◽  
The State ◽  
Coagulation System ◽  
Renal Lesions ◽  
Intravascular Coagulation ◽  
Renal Glomeruli ◽  
Coagulation Mechanism ◽  
Shwartzman Phenomenon ◽  
Do So

SummaryThe role of intravascular coagulation in the production of the generalized Shwartzman phenomenon has been evaluated. The administration of endotoxin to animals prepared with Thorotrast results in activation of the coagulation mechanism with the resultant deposition of fibrinoid material in the renal glomeruli. Anticoagulation prevents alterations in the state of the coagulation system and inhibits development of the renal lesions. Platelets are not primarily involved. Platelet antiserum produces similar lesions in animals prepared with Thorotrast, but appears to do so in a manner which does not significantly involve intravascular coagulation.The production of adrenal cortical hemorrhage, comparable to that seen in the Waterhouse-Friderichsen syndrome, following the administration of endotoxin to animals that had previously received ACTH does not require intravascular coagulation and may not be a manifestation of the generalized Shwartzman phenomenon.

The role of intracanal medicaments in inhibition of bacteria isolated from root canals of infected primary molars

2019 ◽  
Vol 14 (1) ◽  
pp. 92
Author(s):  
Dr. Maha Abdul- Kareem Mahmood ◽  
Dr. Huda Elias Ali ◽  
Dr. Haraa Khairi Abdul-Kadher
Keyword(s):  
Antimicrobial Activity ◽  
Streptococcus Mutans ◽  
Normal Saline ◽  
Root Canal ◽  
Primary Teeth ◽  
Primary Molars ◽  
Root Canals ◽  
Etiologic Agents ◽  
Micro Organisms

Microbes are considered as the primary etiologic agents in endodontic diseases.Disinfection of the root canal is obtained by the combined effect of biomechanicalpreparation, irrigation and intra canal medicament. The aim of the present study wasto assess the antimicrobial activity of intracanal medicaments (formocresol andEndosepton) against two micro organisms (Streptococcus mutans and staphylococcusaureus) isolated from 15 necrotic pulps of primary molars indicated for pulpectomyprocedure. The samples were cultured, and purified using microbiological evaluation.Broth dilution test was performed in our study by preparing test tubes containing10 ml of BHI broth (pH. 7) which then inoculated with strains of the tested bacteriaand incubated at 37 C° for 24 h. After over night incubaction, ten fold dilution weremade in test tubes containing 9 ml of normal saline by adding 1 ml of the inoculum tothe first tube . Then from dilution 10-1 , 0.1 ml of cell suspension was added to 9.9 mlof formocresol and endosepton, then 0.1 ml was taken and spread on duplicates ofBHI agar plates at different intervals and incubated aerobically for 24 h. at 37 C°.Colonies on the plates were counted after incubation and CFU/mL (colony formingunit) was calculated. Our results indicating that there were no significant differencesbetween the intracanal medicaments, but there were high significant differencesbetween the intervals time of the study. We concluded that both materials had greatantibacterial effect against the pathogens commonly isolated from necrotic pulpaltissue of primary teeth.

‘Wheels have been set in motion’: Geocentrism and Relativity in Tom Stoppard’s Rosencrantz and Guildenstern Are Dead

2018 ◽  
Author(s):  
Liliane Campos
Keyword(s):  
20Th Century ◽  
Film Adaptation ◽  
Frames Of Reference ◽  
Quantum Uncertainty ◽  
Galilean Relativity ◽  
Modern Physics ◽  
20Th Century Physics ◽  
Time Specific ◽  
Do So

By decentring our reading of Hamlet, Stoppard’s tragicomedy questions the legitimacy of centres and of stable frames of reference. So Liliane Campos examines how Stoppard plays with the physical and cosmological models he finds in Hamlet, particularly those of the wheel and the compass, and gives a new scientific depth to the fear that time is ‘out of joint’. In both his play and his own film adaptation, Stoppard’s rewriting gives a 20th-century twist to these metaphors, through references to relativity, indeterminacy, and the role of the observer. When they refer to the uncontrollable wheels of their fate, his characters no longer describe the destruction of order, but uncertainty about which order is at work, whether heliocentric or geocentric, random or tragic. When they express their loss of bearings, they do so through the thought experiments of modern physics, from Galilean relativity to quantum uncertainty, drawing our attention to shifting frames of reference. Much like Schrödinger’s cat, Stoppard’s Rosencrantz and Guildenstern are both dead and alive. As we observe their predicament, Campos argues, we are placed in the paradoxical position of the observer in 20th-century physics, and constantly reminded that our time-specific relation to the canon inevitably determines our interpretation.

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