scholarly journals Impact of Microbial Iron Oxide Reduction on the Transport of Diffusible Tracers and Non-diffusible Nanoparticles in Soils

2018 ◽  
Author(s):  
Xiaolong Liang ◽  
Mark Radosevich ◽  
Frank Löffler ◽  
Sean M. Schaeffer ◽  
Jie Zhuang
Keyword(s):  
Iron Oxide ◽  
Electron Donor ◽  
Continuous Flow ◽  
Chemical Properties ◽  
Soil Aggregate ◽  
Time Dependent ◽  
Surface Chemical ◽  
Aggregate Breakdown ◽  
Before And After ◽  
Soil Colloids

AbstractIn situbioremediation to achieve immobilization of toxic metals and radionuclides or detoxification of chlorinated solvents relies on electron donor additions. This practice promotes microbial Fe(III)-oxide mineral reduction that could change soil pore structure, release soil colloids, alter matrix surface properties, and cause the formation of secondary (i.e., reduced) Fe-mineral phases. These processes in turn may impact rates of bioremediation, groundwater quality, and ultimately contaminant fate. Continuous flow columns packed with water-stable soil aggregates high in Fe-oxides were infused with artificial groundwater containing acetate as electron donor and operated for 20 or 60 days inside an anoxic chamber. Soluble Fe(II) and soil colloids were detected in the effluent within one week after initiation of the acetate addition, demonstrating Fe(III)-bioreduction and colloid formation. Br-, 2,6-difluorobenzoate (DFBA), and silica-shelled silver nanoparticles (SSSNP) were selected as diffusible tracer, low-diffusible tracer, and non-diffusible nanoparticles, respectively, to perform transport experiments before and after the active 20-day bioreduction phase, with an aim of assessing the changes in soil structure and surface chemical properties resulting from Fe(III)-bioreduction. The transport of diffusible Br-was not influenced by the Fe(III)-bioreduction as evidenced by identical breakthrough curves before and after the introduction of acetate. Low-diffusible DFBA showed earlier breakthrough and less tailing after the bioreduction, suggesting alterations in flow paths and surface chemical properties of the soils. Similarly, non-diffusible SSSNP exhibited early breakthrough and enhanced transport after the bioreduction phase. Unexpectedly, the bioreduction caused complete retention of SSSNP in the soil columns when the acetate injection was extended from 20 days to 60 days, though no changes were observed for Br-and DFBA during the extended bioreduction period. The large change in the transport of SSSNP was attributed to the enhancement of soil aggregate breakdown and soil colloid release causing mechanical straining of SSSNP and the exposure of iron oxide surfaces previously unavailable within aggregate interiors favorable to the attachment of SSSNP. These results demonstrate that microbial activity can affect soil properties and transport behaviors of diffusivity-varying solutes and colloids in a time dependent fashion, a finding with implication for interpreting the data generated from soil column experiments under continuous flow.HighlightsFe(III)-bioreduction causes time-dependent aggregate breakdown and colloid release.Short-term bioreduction alters soil aggregate surface chemistry and tracer transport.Electron donor amendment enhances transport of nanoparticle tracer.

Solvent mediated surface engineering of α-Fe2O3nanomaterials: facet sensitive energy storage materials

CrystEngComm ◽  
2015 ◽  
Vol 17 (47) ◽  
pp. 9203-9215 ◽  
Author(s):  
Rasmita Barik ◽  
Mamata Mohapatra
Keyword(s):  
Energy Storage ◽  
Iron Oxide ◽  
Surface Engineering ◽  
Chemical Properties ◽  
Energy Storage Materials ◽  
Surface Chemical ◽  
Storage Materials

The surface chemical properties of iron oxide nanomaterials are keenly studied to explore their potential for many future applications.

DEVELOPMENT OF A RAPID CONTINUOUS FLOW SALT LEACHING KIT FOR FABRICATION OF POLY(3-HYDROXYBUTYRIC ACID-CO-3-HYDROXYVALERATE) (PHBV) POROUS 3-D SCAFFOLD

2015 ◽  
Vol 75 (1) ◽  
Author(s):  
Syazwan Aizad ◽  
Badrul Hisham Yahaya ◽  
Saiful Irwan Zubairi
Keyword(s):  
Conventional Method ◽  
Continuous Flow ◽  
Tap Water ◽  
Chemical Properties ◽  
Porous Scaffolds ◽  
Time Saving ◽  
Salt Particle ◽  
Salt Leaching ◽  
Leaching Process ◽  
Highly Efficient

Polyhydroxyalkanoates (PHAs) that are synthesized from bacteria that are predominantly produced by microbial fermentation processes on organic waste, such as palm oil mill effluent (POME), olive oil and kitchen waste, contribute to a sustainable waste management. A great variety of materials from this family can be produced, however the application of PHAs in the production of scaffolds in tissue engineering has been mainly constrained to poly(hydroxybutyrate-co-valerate) (PHBV) due to its highly adjustable physico-chemical properties. One of the common methods in making the 3-D scaffolds is by performing solvent-casting particulate-leaching (SCPL) process, but this process requires a long period of soaking in water to extract the entire salt particle in the 3-D scaffolds. Therefore, the objective of this study is to develop a new method to the conventional method of salt leaching process via a highly efficient continuous flow leaching kit. The salt leaching process was carried out by (1) immersing the 3-D porous scaffolds in a fabricated static container containing tap water and (2) by allowing a pre-setting continuous flow rate of water. The concentration of sodium chloride (NaCl) was calculated periodically for both processes based on the salt standard calibration curve. The results showed that the exhaustive salt leaching of the conventional process occurred at 48 ± 5 hrs with the needs of changing the water twice a day. In contrast, the exhaustive salt leaching process via continuous flow leaching kit occurred at 40 ± 5 mins, 72 times faster than the conventional method (p<0.05). Therefore, the salt leaching process using continuous flow leaching kit can be considered a highly efficient and time saving procedure as compared to the conventional method.  

scholarly journals Enzyme kinetics and metabolic control. A method to test and quantify the effect of enzymic properties on metabolic variables

1990 ◽  
Vol 269 (3) ◽  
pp. 697-707 ◽  
Author(s):  
L Acerenza ◽  
H Kacser
Keyword(s):  
Enzyme Concentration ◽  
Time Dependent ◽  
Experimental Systems ◽  
State Approximation ◽  
Metabolic Systems ◽  
Steady State Approximation ◽  
Before And After ◽  
Factor Alpha ◽  
Metabolic Variables ◽  
Time Invariant

It is usual to study the sensitivity of metabolic variables to small (infinitesimal) changes in the magnitudes of individual parameters such as an enzyme concentration. Here, the effect that a simultaneous change in all the enzyme concentrations by the same factor alpha (Co-ordinate-Control Operation, CCO) has on the variables of time-dependent metabolic systems is investigated. This factor alpha can have any arbitrary large value. First, we assume, for each enzyme measured in isolation, the validity of the steady-state approximation and the proportionality between reaction rate and enzyme concentration. Under these assumptions, any time-invariant variable may behave like a metabolite concentration, i.e. S alpha = Sr (S-type), or like a flux, i.e. J alpha = alpha Jr (J-type). The subscripts r and alpha correspond to the values of the variable before and after the CCO respectively. Similarly, time-dependent variables may behave according to S alpha (t/alpha) = Sr (t) (S-type) or to J alpha (t/alpha) = alpha J r (t) (J-type). A method is given to test these relationships in experimental systems, and to quantify deviations from the predicted behaviour. A positive test for deviations proves the violation of some of the assumptions made. However, the breakdown of the assumptions in an enzyme-catalysed reaction, studied in isolation, may or may not affect significantly the behaviour of the system when the component reaction is embedded in the metabolic network.

Identification of Amber and the Copal under Heat Pressurized Process

2012 ◽  
Vol 554-556 ◽  
pp. 2112-2115
Author(s):  
Hui Li ◽  
Xuan Wang ◽  
Yong Zhu ◽  
Qin Ren
Keyword(s):  
Chemical Properties ◽  
Peak Position ◽  
Exothermic Peak ◽  
Endothermic Peak ◽  
Scanning Calorimetry ◽  
Natural Resin ◽  
Before And After ◽  
Artificial Heat ◽  
Physical And Chemical ◽  
And Chemical Properties

Amber and copal belong to the natural resin, which are similar and transitional in the physical and chemical properties. The artificial heat-pressurized treatment is contributed to the polymerization of the natural copal, and turns into green, yellow-green and deep orange-yellow copal. It is very difficult to identify amber from the heat- pressurized treatment copal only based on the gemological parameters.The thermal behavior of amber and the copal before and after heat-pressurized treatment were analyzed by means of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance(NMR). The results show that amber exists an evident endothermic peak around 123~132°C, and copal reveals an obvious endothermic peak at about 174~178°C, and the heat pressurized treatment copal occurs a clear exothermic peak around 150~152°C. The differences between endothermic or exothermic transition and peak position reveal occurring thermal oxidation or the bond breaking or the melting, which are of great significance in the identification.

Evaluation of Ship Performance Using Operation Records

2018 ◽  
Author(s):  
Kenichi Fukuda ◽  
Yoshihisa Okada ◽  
Akinori Okazaki ◽  
Hiroyuki Adachi ◽  
Yuichiro Hisamuara ◽  
...  
Keyword(s):  
Big Data ◽  
Fuel Oil ◽  
Time Dependent ◽  
Oil Consumption ◽  
Sea Trial ◽  
Before And After ◽  
Report Data ◽  
Unique Approach ◽  
Performance Conditions ◽  
Ship Performance

Recently, the big data can be employed as the economical ship operating or evaluation of ship performance conditions. However, such data cannot be easily obtained and analyzed for every ship. In this case, for example, an evaluation of ship performance during operation is usually dependent on ship owner’s experience. The time-dependent ship performance is an essential topic for ship owners because if they realize their current ship performance, they can implement something such as hull or propeller cleaning for their economical operation. This study is focused on the usage of noon report data rather than the big data due to their obtainability. Usually, such data are considered as references because different ship operational condition and environmental condition obscure current ship performance. However, our unique approach, which is used integrally the noon report data such as BHP, propeller revolution and fuel oil consumption, ship sea trial data and propeller performance, can be evaluated ship performance during ship in service. The analyzed output data can be produced as increasing of ship resistance (delta Rw) versus ship performance efficiency, fuel oil consumption (ton per day) or sea margin. Under this output conditions, it can be comparable at same conditions even though the conditions of operations are different. Therefore, this analyzed data has a potential ability to have a look at ship performance conditions during ship in service. The purpose of this paper is to introduce our unique approach using noon data for time-dependent ship performance and then discuss the verification of this approach. As the case study, the noon report data for Japanese domestic bulker was chosen and the ship performance was evaluated in terms of different points of views. It was done comparing the conditions of before and after dry dock to evaluate our approach. In addition, the potential application of this approach will be discussed in this paper.

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