scholarly journals A Theoretical Multifractal Model for Assessing Urea Release from Chitosan Based Formulations

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1264 ◽  
Author(s):  
Manuela Maria Iftime ◽  
Stefan Andrei Irimiciuc ◽  
Maricel Agop ◽  
Marian Angheloiu ◽  
Lacramioara Ochiuz ◽  
...  
Keyword(s):  
Empirical Data ◽  
Polarized Light ◽  
First Order ◽  
Fertilizer Release ◽  
Urea Release ◽  
Release Data ◽  
First Time ◽  
Good Agreement

This paper reports the calibration of a theoretical multifractal model based on empirical data on the urea release from a series of soil conditioner systems. To do this, a series of formulations was prepared by in situ hydrogelation of chitosan with salicylaldehyde in the presence of different urea amounts. The formulations were morphologically characterized by scanning electron microscopy and polarized light microscopy. The in vitro urea release was investigated in an environmentally simulated medium. The release data were fitted on five different mathematical models, Korsmeyer–Peppas, Zero order, First order, Higuchi and Hixson–Crowell, which allowed the establishment of a mechanism of urea release. Furthermore, a multifractal model, used for the fertilizer release for the first time, was calibrated using these empirical data. The resulting fit was in good agreement with the experimental data, validating the multifractal theoretical model.

scholarly journals INTEGRINS MEDIATE PLACENTAL EXTRACELLULAR VESICLE TRAFFICKING TO LUNG AND LIVER IN VIVO

2020 ◽  
Author(s):  
Sean L. Nguyen ◽  
Soo Hyun Ahn ◽  
Jacob W. Greenberg ◽  
Benjamin W. Collaer ◽  
Dalen W. Agnew ◽  
...  
Keyword(s):  
Immune Cells ◽  
Extracellular Vesicle ◽  
Dependent Manner ◽  
Cellular Phenotype ◽  
Reporter Mouse ◽  
Membrane Bound ◽  
First Time

ABSTRACTMembrane-bound extracellular vesicles (EVs) mediate intercellular communication in all organisms, and those produced by placental mammals have become increasingly recognized as significant mediators of fetal-maternal communication. Here, we aimed to identify maternal cells targeted by placental EVs and elucidate the mechanisms by which they traffic to these cells. Exogenously administered pregnancy-associated EVs traffic specifically to the lung; further, placental EVs associate with lung interstitial macrophages and liver Kupffer cells in an integrin-dependent manner. Localization of EV to maternal lungs was confirmed in unmanipulated pregnancy using a transgenic reporter mouse model, which also provided in situ and in vitro evidence that fetally-derived EVs, rarely, may cause genetic alteration of maternal cells. These results provide for the first time direct in vivo evidence for targeting of placental EVs to maternal immune cells, and further, evidence that EVs can alter cellular phenotype.

scholarly journals Anaerobic digestion is the dominant pathway for pit latrine decomposition and is limited by intrinsic factors

2019 ◽  
Vol 79 (12) ◽  
pp. 2242-2250 ◽  
Author(s):  
Miriam H. A. van Eekert ◽  
Walter T. Gibson ◽  
Belen Torondel ◽  
Faraji Abilahi ◽  
Bernard Liseki ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Oxygen Demand ◽  
In Vitro Tests ◽  
Full Potential ◽  
Water Addition ◽  
Intrinsic Factors ◽  
Pit Latrine ◽  
First Time

Abstract In vitro methods were used to assess the full potential for decomposition (measured as biogas formation) from pit latrine samples taken from the top layer of 15 Tanzanian latrines. We found considerable variability in the decomposition rate and extent. This was compared with decomposition in the same latrines, measured by comparing top layer composition with fresh stools and deeper (older) layers, to assess whether this potential was realised in situ. Results showed a close match between the extent of organic material breakdown in situ and in vitro, indicating that anaerobic digestion is the dominant pathway in latrines. The average potential decrease in chemical oxygen demand (COD) (determined as methane production in vitro within 60 days) and actual measured decrease in situ are 68.9% ± 11.3 and 69.7% ± 19.4, respectively. However in the in vitro tests, where samples were diluted in water, full decomposition was achieved in 2 months, whereas in situ it can take years; this suggests that water addition may offer a simple route to improving latrine performance. The results also allowed us to estimate, for the first time to our knowledge using experimental data, the contribution that latrines make to greenhouse gas emissions globally. This amounts to ∼2% of annual US emissions.

Gas Phase and Surface Reactions in Mocvd of GaAs from Triethylgallium, Trimethylgallium, and Organometallic Arsenic Precursors

1988 ◽  
Vol 131 ◽  
Author(s):  
Thomas R. Omstead ◽  
Penny M. Van Sickle ◽  
Klavs F. Jensen
Keyword(s):  
Gas Phase ◽  
Low Temperatures ◽  
Surface Reactions ◽  
Rate Data ◽  
Gas Phase Reactions ◽  
Heated Zone ◽  
Model Predictions ◽  
First Time ◽  
Good Agreement

ABSTRACTThe growth of GaAs from triethylgallium (TEG) and trimethylgallium (TMG) with tertiarybutylarsine (tBAs), triethylarsenic (TEAs), and trimethylarsenic (TMAs), has been investigated by using a reactor equipped with a recording microbalance for in situ rate measurements. Rate data show that the growth with these precursors is dominated by the formation of adduct compounds in the gas lines, by adduct related parasitic gas phase reactions in the heated zone, and by the surface reactions. A model is proposed for the competition between deposition reactions and the parasitic gas phase reactions. Model predictions are in very good agreement with experimental data for all combinations of precursors except for TEG/TMAs where extensive gallium droplet formation is observed at low temperatures. Growth of reasonable quality GaAs with Hall mobilities of 7600 cm2/Vs at 77 K using TEG and tBAs is reported for the first time.

Polarized light scattering of nucleosomes and polynucleosomes-in situ and in vitro studies

1991 ◽  
Vol 38 (7) ◽  
pp. 670-678 ◽  
Author(s):  
A. Diaspro ◽  
M. Bertolotto ◽  
L. Vergani ◽  
C. Nicolini
Keyword(s):  
Light Scattering ◽  
Polarized Light ◽  
In Vitro Studies

scholarly journals Estimation of ship emission rates at a major shipping lane by long path DOAS measurements

2021 ◽  
Author(s):  
Kai Krause ◽  
Folkard Wittrock ◽  
Andreas Richter ◽  
Stefan Schmitt ◽  
Denis Pöhler ◽  
...  
Keyword(s):  
Emission Factors ◽  
Emission Rates ◽  
River Elbe ◽  
Gaussian Plume ◽  
Remote Sensing Techniques ◽  
One Year ◽  
First Time ◽  
Good Agreement ◽  
Ship Emission

Abstract. Ships are an important source of SO2 and NOx, which are key parameters of air quality. Monitoring of ship emissions is usually carried out using in situ instruments on land, which depend on favourable wind conditions to transport the emitted substances to the measurement site. Remote sensing techniques such as long path DOAS (LP-DOAS) measurements can supplement those measurements, especially in unfavourable meteorological conditions. In this study one year of LP-DOAS measurements made across the river Elbe close to Hamburg (Germany) have been evaluated. Peaks (i.e. elevated concentrations) in the NO2 and SO2 time series were assigned to passing ships and a method to derive emission rates of SO2, NO2 and NOx from those measurements using a Gaussian plume model is presented. 7402 individual ship passages have been monitored and their respective NOx, SO2 and NO2 emission rates have been derived. The emission rates, coupled with the knowledge of the ship type, ship size and ship speed have been analysed. Emission rates are compared to emission factors from previous studies and show good agreement. In contrast to emission factors (in gram per kilogram fuel) the derived emission rates (in gram per second) do not need further knowledge about the fuel consumption of the ship. To our knowledge this is the first time emission rates of air pollutants from individual ships have been derived from LP-DOAS measurements.

scholarly journals A method for monitoring hydrological conditions beneath herbaceous wetlands using multi-temporal ALOS PALSAR coherence data

2015 ◽  
Vol XL-7/W4 ◽  
pp. 221-226 ◽  
Author(s):  
M. Zhang ◽  
Z. Li ◽  
B. Tian ◽  
J. Zhou ◽  
J. Zeng
Keyword(s):  
Effective Area ◽  
Interferometric Synthetic Aperture Radar ◽  
Alos Palsar ◽  
Hydrological Conditions ◽  
In Situ Data ◽  
Key Indicator ◽  
Multi Temporal ◽  
First Time ◽  
Good Agreement

Reed marshes, the world’s most widespread type of wetland vegetation, are undergoing major changes as a result of climate changes and human activities. The presence or absence of water in reed marshes has a significant impact on the whole ecosystem and remains a key indicator to identify the effective area of a wetland and help estimate the degree of degeneration. Past studies have demonstrated the use of interferometric synthetic aperture radar (InSAR) to map water-level changes for flooded reeds. However, the identification of the different hydrological states of reed marshes is often poorly understood. The analysis given in this paper shows that L-band interferometric coherence is very sensitive to the water surface conditions beneath reed marshes and so can be used as classifier. A method based on a statistical analysis of the coherence distributions for wet and dry reeds using InSAR pairs was, therefore, investigated in this study. The experimental results were validated by in-situ data and showed very good agreement. This is the first time that information about the water cover under herbaceous wetlands has been derived using interferometric coherence values. This method can also effectively and easily be applied to monitor the hydrological conditions beneath other herbaceous wetlands.

scholarly journals 5-Fluorouracil Release from Chitosan-Based Matrix.Experimental and Theoretical Aspects

2020 ◽  
Vol 57 (3) ◽  
pp. 180-188
Author(s):  
Roxana Iancu ◽  
Stefan Andrei Irimiciuc ◽  
Maricel Agop ◽  
Mihail Frasila ◽  
Maria-Alexandra Paun ◽  
...  
Keyword(s):  
Drug Release ◽  
Polarized Light ◽  
Crosslinking Density ◽  
Fickian Diffusion ◽  
Release Mechanism ◽  
Morphological Aspects ◽  
Drug Release Mechanism ◽  
The Matrix

A series of four drug release formulations based on 5-fluorouracil encapsulated into a chitosan-based matrix were prepared by in situ hydrogelation with 3,7-dimethyl-2,6-octadienal. The formulations were investigated from structural and morphological aspects by FTIR spectroscopy, polarized light microscopy and scanning electron microscopy. It was established that 5-fluorouracil was anchored into the matrix as crystals, whose dimension varied as a function of the crosslinking density. The in vitro drug release simulated into a media mimicking the physiological environment revealed a progressive release of the 5-fluorouracil, in close interdependence with the crosslinking density. In the context of Pharmacokinetics behavioral analysis, a new mathematical procedure for describing drug release dynamics in polymer-drug complex system is proposed. Assuming that the dynamics of polymer-drug system�s structural units take place on continuous and nondifferentiable curves (multifractal curves), we show that in a one-dimensional hydrodynamic formalism of multifractal variables the drug release mechanism (Fickian diffusion, non-Fickian diffusion, etc) are given through synchronous dynamics at a differentiable and non-differentiable scale resolutions. Finally, the model is confirmed by the empirical data.

scholarly journals Estimation of ship emission rates at a major shipping lane by long-path DOAS measurements

2021 ◽  
Vol 14 (8) ◽  
pp. 5791-5807
Author(s):  
Kai Krause ◽  
Folkard Wittrock ◽  
Andreas Richter ◽  
Stefan Schmitt ◽  
Denis Pöhler ◽  
...  
Keyword(s):  
Emission Factors ◽  
Optical Absorption Spectroscopy ◽  
Emission Rates ◽  
River Elbe ◽  
Gaussian Plume ◽  
Remote Sensing Techniques ◽  
First Time ◽  
Good Agreement ◽  
Ship Emission

Abstract. Ships are an important source of SO2 and NOx, which are key parameters of air quality. Monitoring of ship emissions is usually carried out using in situ instruments on land, which depend on favourable wind conditions to transport the emitted substances to the measurement site. Remote sensing techniques such as long-path differential optical absorption spectroscopy (LP-DOAS) measurements can supplement those measurements, especially in unfavourable meteorological conditions. In this study 1 year of LP-DOAS measurements made across the river Elbe close to Hamburg (Germany) have been evaluated. Peaks (i.e. elevated concentrations) in the NO2 and SO2 time series were assigned to passing ships, and a method to derive emission rates of SO2, NO2 and NOx from those measurements using a Gaussian plume model is presented. A total of 7402 individual ship passages have been monitored, and their respective NOx, SO2 and NO2 emission rates have been derived. The emission rates, coupled with the knowledge of the ship type, ship size and ship speed, have been analysed. Emission rates are compared to emission factors from previous studies and show good agreement. In contrast to emission factors (in grams per kilogram fuel), the derived emission rates (in grams per second) do not need further knowledge about the fuel consumption of the ship. To our knowledge this is the first time emission rates of air pollutants from individual ships have been derived from LP-DOAS measurements.

scholarly journals Expression of an acidic isoform of calponin in rat brain: western blots on one- or two-dimensional gels and immunolocalization in cultured cells

1995 ◽  
Vol 306 (1) ◽  
pp. 211-215 ◽  
Author(s):  
H Trabelsi-Terzidis ◽  
A Fattoum ◽  
A Represa ◽  
F Dessi ◽  
Y Ben-Ari ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Rat Brain ◽  
Cultured Cells ◽  
Two Dimensional ◽  
Brain Protein ◽  
Western Blots ◽  
Calmodulin Binding ◽  
First Time ◽  
Good Agreement

Calponin, an actin- and Ca(2+)-calmodulin-binding protein characterized as an inhibitory factor of the smooth-muscle actomyosin activity, has also been shown to be present in some non-muscle cells. However, there is a controversy as to whether calponin is present or not in brain. Several laboratories indicate that this protein is absent in chicken or bovine brains, while Applegate et al. [Applegate, Feng, Green and Taubman (1994) J. Biol. Chem. 269, 10683-10690] have recently reported the identification of an mRNA specific for a 36 kDa non-muscle calponin analogue in homogenates of rat brains. For the first time we demonstrate, by Western blots and in situ immunofluorescence localization using monoclonal as well as affinity-purified polyclonal antibody to gizzard calponin, that a 36-37 kDa and a 35-36 kDa calponin-like proteins are expressed respectively in pig and rat brains and in rat cerebellar cultured cells. The acidic pI (5.2-5.4) of the rat brain protein revealed by isoelectric focusing is in good agreement with that of the protein coded for by the calponin isoform mRNA described by Applegate et al. and is different from that of the protein from chicken gizzard (pI 9.9). Brain calponin-like protein is different from two other Ca(2+)-calmodulin-binding proteins previously identified in brain, namely caldesmon and adducin, and from tropomyosin.

scholarly journals Action of liproprotein lipase on apoprotein-depleted chylomicrons

1978 ◽  
Vol 175 (1) ◽  
pp. 53-61 ◽  
Author(s):  
T W Lukens ◽  
J Borensztajn
Keyword(s):  
Lipoprotein Lipase ◽  
Physiological Role ◽  
Rat Plasma ◽  
High Density Lipoproteins ◽  
Complete Restoration ◽  
Immobilized Trypsin ◽  
Plasma High Density ◽  
First Time

1. Rat lymph chylomicrons were exposed to soluble and to immobilized trypsin. This treatment caused no detectable changes in the chylomicron structure or lipid composition, but did result in virtually total depletion of all their tetramethylurea-soluble apoproteins. 2. The capacity of these apoprotein-depleted chylomicrons to act as substrate for lipoprotein lipase in vitro and in situ (i.e. isolated perfused rat heart) was decreased by about 90 and 75% respectively, compared with intact chylomicrons. 3. On incubation with rat plasma high-density lipoproteins, trypsin-treated chylomicrons readily acquired a full apoprotein complement. This resulted in the complete restoration of their capacity to act as substrate for lipoprotein lipase both in vitro and in situ. 4. It is suggested that with the use of try,sin-treated chylomicrons it is now possible for the first time to investigate the physiological role that individual apoproteins play in the catabolism of triacylglycerol-rich lipoproteins by lipoprotein lipase.

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