scholarly journals Modeling Surface Area to Volume Effects on Borosilicate Glass Dissolution

1992 ◽  
Vol 294 ◽  
Author(s):  
William L. Bourcier ◽  
W. L. Ebert ◽  
X. Feng
Keyword(s):  
Ion Exchange ◽  
Surface Area ◽  
Ph Effect ◽  
Volume Ratio ◽  
Solution Ph ◽  
Exchange Effect ◽  
Dissolution Experiment ◽  
Glass Dissolution ◽  
Time Value ◽  
Long Time

ABSTRACTWe simulated the reaction of SRL-131 glass with equilibrated J-13 water in order to investigate the effects of surface area to volume ratio (SAN/) on glass dissolution. We show that glass-fluid ion exchange causes solution pH to rise to progressively higher values as SA/V increases. Because the ion exchange is rapid relative to the duration of the glass dissolution experiment, the pH effect does not scale with (SA/V)*time. Experiments compared at the same (SA/V)*time value therefore have different pHs, with higher pHs at higher SA/V ratios. Both experimental data and our simulation results show similar trends of increasing reaction rate as a function of SAN ratio when scaled to (SA/V)*time. Glasses which react in systems of differing SA/V ratio therefore follow different reaction paths and high SAN ratios cannot be used to generate data which accurately scales to long time periods unless the ion exchange effect is taken into account. We suggest some simple test designs which enable more reliable high SAN accelerated tests.

scholarly journals Road salt compromises functional morphology of larval gills in populations of an amphibian

2020 ◽  
Author(s):  
Richard V. Szeligowski ◽  
Jules A. Scanley ◽  
Christine C. Broadbridge ◽  
Steven P. Brady
Keyword(s):  
Gas Exchange ◽  
Ion Exchange ◽  
Surface Area ◽  
Volume Ratio ◽  
Rana Sylvatica ◽  
Early Life History ◽  
Lower Surface ◽  
Secondary Salinization ◽  
Elevated Salinity ◽  
Gill Morphology

AbstractThroughout much of the world, winter deicing practices have led to secondary salinization of freshwater habitats, where numerous taxa are vulnerable to elevated salinity. Many amphibians are of particular concern because of their permeable skin and reliance on small ponds and pools, where salinity levels can be high. The early life-history stages of amphibians that develop in these habitats are especially sensitive to salt exposure. Larvae developing in salt-polluted environments must osmoregulate through ion exchange in gills. While salt-induced changes to the physiology of ion exchange in amphibian gills is generally understood, functionally relevant changes in gill morphology remain poorly described. Yet the structure of gills should be an important component affecting their ionoregulatory capacity, for instance in terms available surface area. Larval amphibian gills also play critical roles in gas exchange and foraging. Thus, changes in gill morphology due to salt pollution potentially affect not only osmoregulation, but also respiration and feeding. Here, we used a chronic exposure experiment to quantify the effect of salinity on larval gill morphology in populations of the wood frog (Rana sylvatica). We measured a suite of morphological traits on gill tufts, where ionoregulation and gas exchange occur, and on gill filters, which are used in feeding. Larvae raised in high salinity conditions had gill tufts with lower surface area to volume ratio, while epithelial cells on these tufts were less circular but occurred at higher densities. Gill filters showed increased spacing, which can potentially reduce their efficiency in filtering food particles. Together, these changes seem likely to diminish the ionoregulatory and respiratory capacity of gill tufts, and compromise feeding functionality of gill filters. Thus, a singular change in the aquatic environment from a widespread pollutant has the potential to generate a suite of consequences via changes in gill morphology. Critically, this suite of negative effects is likely most detrimental in salinized environments, where ionoregulatory demands are higher, which in turn should increase respiratory demands along with energy acquisition demands through foraging.

Evaluation of Nanotechniques and Conventional Techniques for the Removal of Dioxins

2018 ◽  
Vol 9 (1) ◽  
pp. 79-84
Author(s):  
Vaishali V. Shahare ◽  
Rajni Grover ◽  
Suman Meena
Keyword(s):  
Soil Sample ◽  
Human Health ◽  
Surface Area ◽  
Contaminated Soil ◽  
Conventional Treatment ◽  
Volume Ratio ◽  
Soil Samples ◽  
Dioxins And Furans ◽  
Palladized Iron ◽  
The Impact

Background: The persistent dioxins/furans has caused a worldwide concern as they influence the human health. Recent research indicates that nonmaterial may prove effective in the degradation of Dioxins/furans. The nanomaterials are very reactive owing to their large surface area to volume ratio and large number of reactive sites. However, nanotechnology applications face both the challenges and the opportunities to influence the area of environmental protection. Objective: i) To study the impact of oil mediated UV-irradiations on the removal of 2,3,7,8-TCDD, 2,3,7,8-TCDF, OCDD and OCDF in simulated soil samples. ii) To compare the conventional treatment methods with the modern available nanotechniques for the removal of selected Dioxins/furans from soil samples. Methods: The present work has investigated an opportunity of the degradation of tetra and octachlorinated dioxins and furans by using oil mediated UV radiations with subsequent extraction of respective dioxins/furans from soils. The results have been compared with the available nanotechniques. Results: The dioxin congeners in the simulated soil sample showed decrease in concentration with the increase in the exposure time and intensity of UV radiations. The dechlorination of PCDD/Fs using palladized iron has been found to be effective. Conclusion: Both the conventional methods and nanotechnology have a dramatic impact on the removal of Dioxins/furans in contaminated soil. However, the nanotechniques are comparatively costlier and despite the relatively high rates of PCDDs dechlorination by Pd/nFe, small fraction of the dioxins are recalcitrant to degradation over considerable exposure times.

scholarly journals Precise regulation of the relative rates of surface area and volume synthesis in bacterial cells growing in dynamic environments

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Handuo Shi ◽  
Yan Hu ◽  
Pascal D. Odermatt ◽  
Carlos G. Gonzalez ◽  
Lichao Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Time Delay ◽  
Surface Area ◽  
Environmental Changes ◽  
Volume Ratio ◽  
Dynamic Environments ◽  
Bacterial Cells ◽  
Bacterial Growth Rate ◽  
State Size ◽  
Insight Into

AbstractThe steady-state size of bacterial cells correlates with nutrient-determined growth rate. Here, we explore how rod-shaped bacterial cells regulate their morphology during rapid environmental changes. We quantify cellular dimensions throughout passage cycles of stationary-phase cells diluted into fresh medium and grown back to saturation. We find that cells exhibit characteristic dynamics in surface area to volume ratio (SA/V), which are conserved across genetic and chemical perturbations as well as across species and growth temperatures. A mathematical model with a single fitting parameter (the time delay between surface and volume synthesis) is quantitatively consistent with our SA/V experimental observations. The model supports that this time delay is due to differential expression of volume and surface-related genes, and that the first division after dilution occurs at a tightly controlled SA/V. Our minimal model thus provides insight into the connections between bacterial growth rate and cell shape in dynamic environments.

Controlled Release of Active Substance from Biodegradable Copolymer Matrix

2006 ◽  
Vol 510-511 ◽  
pp. 798-801
Author(s):  
Hyung Suk So ◽  
Hyun Chul Shin ◽  
Beom Suk Kim ◽  
Yeong Seok Yoo
Keyword(s):  
Methylene Blue ◽  
Active Substance ◽  
Phosphate Buffer Solution ◽  
Ultra Violet ◽  
Hydroxyl Groups ◽  
Buffer Solution ◽  
Solution Ph ◽  
Effective Discharge ◽  
Constant Rate ◽  
Long Time

The purpose of this study is to develop a new system to control effective discharge of active substances such as agricultural chemicals. To synthesize a naturally dissolvable polymer; ε-caprolactone and diglycolide were copolymerized with ethylene glycol as an initiator to produce macrodiol. As macrodiol has hydroxyl groups in both ends, they are modified with methacryloyl chloride for photochemical networking. After standard macromonomer produced by this procedure was physically mixed with methylene blue, it was networked with ultra-violet rays to be filmed. This film is naturally dissolvable and hydrolytic. As a result of hydrolytic test with a crosslinked structure of 10 % methylene blue, it decreased by 9 % for seven weeks in 37 °C phosphate buffer solution (pH = 7). Thus, we verified that active substance can be discharged from a crosslinked structure for a long time at a constant rate under room temperature.

scholarly journals Pyromorphite formation from montmorillonite adsorbed lead

Mineralogia ◽  
2011 ◽  
Vol 42 (2-3) ◽  
pp. 75-91 ◽  
Author(s):  
Tomasz Bajda ◽  
Tomasz Marchlewski ◽  
Maciej Manecki
Keyword(s):  
Ion Exchange ◽  
Aqueous Solutions ◽  
Phosphate Concentration ◽  
High Concentration ◽  
Exchange Effect ◽  
System A ◽  
New Phase

Pyromorphite formation from montmorillonite adsorbed lead The reaction of Pb-adsorbed montmorillonite with aqueous solutions of PO4 and Cl ions results in the decrease in phosphate concentration associated with the formation of a new phase - pyromorphite Pb5(PO4)3Cl. Pyromorphite crystals range in size from hundreds of nm to several tens of μm, depending on the PO4, K, and Ca concentrations in the reacting system. A strong ion-exchange effect of K+ and Ca2+ cations on desorption of Pb2+ from Pb-adsorbed montmorillonite was observed. Also, a high concentration of cations leads to a rapid desorption of Pb and the formation of fine pyromorphite crystals. In contrast, low PO4, K and Ca concentrations result in the formation of relatively large euhedral crystals. Final Pb concentrations are much lower in experimental sets than in control experiments with no phosphate present.

Toward a predictive theoretical model for osmolality rise with non-humidified incubation: a randomized, multivariate response-surface study

2021 ◽  
Author(s):  
Steven F Mullen
Keyword(s):  
Mathematical Model ◽  
Response Surface ◽  
Surface Area ◽  
Embryo Culture ◽  
Culture Medium ◽  
Conflicts Of Interest ◽  
Volume Ratio ◽  
P Value ◽  
Cook Medical ◽  
Over Time

Abstract STUDY QUESTION What factors associated with embryo culture techniques contribute to the rate of medium osmolality change over time in an embryo culture incubator without added humidity? SUMMARY ANSWER The surface area-to-volume ratio of culture medium (surface area of the medium exposed to an oil overlay), as well as the density and height of the overlaying oil, all interact in a quantitative way to affect the osmolality rise over time. WHAT IS KNOWN ALREADY Factors such as medium volume, different oil types, and associated properties, individually, can affect osmolality change during non-humidified incubation. STUDY DESIGN, SIZE, DURATION Several experimental designs were used, including simple single-factor completely randomized designs, as well as a multi-factor response surface design. Randomization was performed at one or more levels for each experiment. Osmolality measurements were performed over 7 days, with up to 8 independent osmolality measurements performed per treatment group over that time. For the multi-factor study, 107 independent combinations of factor levels were assessed to develop the mathematical model. PARTICIPANTS/MATERIALS, SETTING, METHODS This study was conducted in a research laboratory setting. Commercially available embryo culture medium and oil was used. A MINC incubator without water for humidification was used for the incubation. Osmolality was measured with a vapor pressure osmometer after calibration. Viscometry and density were conducted using a rheometer, and volumetric flasks with an analytical balance, respectively. Data analyses were conducted with several commercially available software programs. MAIN RESULTS AND THE ROLE OF CHANCE Preliminary experiments showed that the surface area-to-volume ratio of the culture medium, oil density, and oil thickness above the medium all contributed significantly (P < 0.05) to the rise in osmolality. A multi-factor experiment showed that a combination of these variables, in the form of a truncated cubic polynomial, was able to predict the rise in osmolality, with these three variables interacting in the model (P < 0.05). Repeatability, as measured by the response of identical treatments performed independently, was high, with osmolality values being ± 2 of the average in most instances. In the final mathematical model, the terms of the equation were significant predictors of the outcome, with all P-values being significant, and only one P-value > 0.0001. LIMITATIONS, REASONS FOR CAUTION Although the range of values for the variables were selected to encompass values that are expected to be encountered in usual embryo culture conditions, variables outside of the range used may not result in accurate model predictions. Although the use of a single incubator type and medium type is not expected to affect the conclusions, that remains an uncertainty. WIDER IMPLICATIONS OF THE FINDINGS Using this predictive model will help to determine if one should be cautious in using a specific system and will provide guidance on how a system may be modified to provide improved stability during embryo culture. STUDY FUNDING/COMPETING INTEREST(S) This study was funded by Cook Medical. The author is a Team Lead and Senior Scientist at Cook Medical. The author has no other conflicts of interest to declare TRIAL REGISTRATION NUMBER N/A.

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