Bioink-formulations based on gelatin methacrylate combined with oxidized cellulose nanofibrils are employed in the present study. The parallel investigation of the printing performance, ...morphological, swelling, and biological properties of the newly developed hydrogels was performed, with inks prepared using methacrylamide-modified gelatins of fish or bovine origin. Scaffolds with versatile and well-defined internal structure and high shape fidelity were successfully printed due to the high viscosity and shear-thinning behavior of formulated inks and then photo-crosslinked. The biocompatibility of 3D-scaffolds was surveyed using human adipose stem cells (hASCs) and high viability and proliferation rates were obtained when in contact with the biomaterial. Furthermore, bioprinting tests were performed with hASCs embedded in the developed formulations. The results demonstrated that the designed inks are a versatile toolkit for 3D bioprinting and further show the benefits of using fish-derived gelatin for biofabrication.
This paper presents complex studies on establishment of derived emission limits for potential radionuclides emitted as gaseous and liquid effluents, during the decommissioning activities (2nd and 3rd ...phases) of a nuclear research reactor, cooled and moderated with distilled water, type VVR-S, owned by the IFIN-HH. In the present paper there are described: the analysis methods and equipment used, the methodologies for calculating doses and the Derived Emission Limits (DEL), the experimentally measured activities of the representative radionuclides found in gaseous and liquid effluents resulted from decommissioning activities, as well as the effective derived limits of liquid and gaseous effluents, applying the calculation methodologies, specific to critical categories of exposed subjects. A constraint effective dose limit for a person from the critical group of 50 μSv/year was considered in calculations. From the comparison of the two series of values, measured released activities and DELs, there has been concluded that for the gaseous effluents they comply with the DELs, while in the case of liquid effluents they are higher and consequently they must be treated as liquid radioactive wastes.
•The DELs for gaseous and liquid effluents in decommissioning were studied.•The impact on the environment and critical group was assessed.•Gamma-ray spectrometry was used to determine the radionuclide composition.•Based on the dosimetry models, the values of conservative DELs were calculated.•The DELs are compliant for gases, not for liquids; require the treatment as rad-waste.
Dihydroceramide desaturase catalyzes the conversion of the innocuous precursor dihydroceramide into a highly bioactive product ceramide. We studied the effect of ...N-(1R,2S)-2-hydroxy-1-hydroxymethyl-2-(2-tridecyl-1-cyclopropenyl)ethyloctanamide (GT11), the first inhibitor of this enzyme, in primary cultured cerebellar neurons. Although desaturase was efficiently inhibited (IC50 of 23 nM), the compound lost its specificity at higher concentrations. From 5 microM upward, GT11 also decreased de novo sphingolipid biosynthesis. Studies with two differentially labeled radioactive analogs of GT11 support that the inhibitor itself and not a downstream metabolic product, interferes with sphingolipid biosynthesis. It is interesting that serine palmitoyltransferase activity decreased in the presence of high concentrations of GT11 in intact cells, but not when added directly into cell homogenates. However, suppression of enzyme transcription could not be detected. But at high concentrations GT11 provoked an accumulation of sphingosine-1-phosphate and especially of dihydrosphingosine-1-phosphate, suggesting a decreased activity of sphingosine-1-phosphate lyase. Enzyme activity measurements indeed supported this assumption. Thus, at higher concentrations, GT11 interferes with lyase activity, inducing an accumulation of sphingoid base phosphates that, in turn, down-regulate serine palmitoyltransferase activity. At low concentrations, however, GT11 is the first specific inhibitor of dihydroceramide desaturase described so far. Considering the proapoptotic and proinflammatory effect of ceramide, GT11 could also turn out to be a novel cell-protective agent.
We studied the metabolism of radioactively labeled safingol (l-threo-dihydrosphingosine) in primary cultured neurons, B104 neuroblastoma cells, and Swiss 3T3 fibroblasts, and compared it to that of ...its natural stereoisomer d-erythro-dihydrosphingosine. Both sphingoid bases are used as biosynthetic precursors for complex sphingolipids, albeit to different rates. Whereas a considerable amount of the natural sphingoid base is also directed to the catabolic pathway (20–66%, cell type dependent), only a minor amount of the nonnatural safingol is subjected to catabolic cleavage, most of it being N-acylated to the respective stereochemical variant of dihydroceramide. Interestingly, N-acylation of safingol to l-threo-dihydroceramide is less sensitive to fumonisin B1 than the formation of the natural d-erythro-dihydroceramide. In addition, safingol-derived l-threo-dihydroceramide, unlike its physiologic counterpart, is not desaturated. Most of it either accumulates in the cells (up to 50%) or is used as a biosynthetic precursor of the respective dihydrosphingomyelin (up to 45%). About 5% is, however, glucosylated and channeled into the glycosphingolipid biosynthetic pathway.
Our results demonstrate that, despite its nonnatural stereochemistry, safingol is recognized and metabolized preferentially by enzymes of the sphingolipid biosynthetic pathway. Furthermore, our data suggest that the cytotoxic potential of safingol is reduced rather than enhanced via its metabolic conversion.
IAP linacs in applied research Martin, D.; Dragusin, M.; Radu, A. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
06/1996, Letnik:
113, Številka:
1
Journal Article
Recenzirano
The results of the applied research with linacs, built in the Institute of Atomic Physics (IAP), in the field of electron beam irradiation of acrylamide-acrylic acid and acrylic acid-vinyl acetate ...aqueous solutions, to produce polymeric flocculants of the PA and PV type, respectively, are presented. The special features of the IAP linacs are also described. The use of low-output-power, high-energy IAP linacs in the field of electron beam processing was mitigated thanks to the remarkable properties of the processes developed for our polymeric flocculants. The absorbed dose levels needed to produce PA and PV flocculant types are rather small, from 0.4 to 1 kGy and from 3 to 4 kGy, respectively. These results helped us to make the assumption that old low-output-power, high-energy linacs are economically attractive for commercial production of these types of flocculants. The estimate of processing rates for a linac of 1 kW output power and 5 to 10 MeV energy is up to 2000 kg/h for the PA type and up to 500 kg/h for the PV type. Due to the ever growing ecological problems we are facing, research and engineering studies are being carried out to put an old ALID-7 linac of 700 W and 5.5 MeV in a pilot station. With the ALID-7 linac it could be possible to satisfy the required production of flocculants for municipal sludge dewatering in our country.
Radiation research results in the field of polymeric materials, obtained in the last few years by electron beam irradiation of aqueous solutions containing appropriate monomer mixtures, such as ...acrylamide, acrylic acid and vinyl acetate, are presented. Two types of polymeric flocculants for waste water treatment and three kinds of hydrogels for agriculture and medicine are described. The effects of radiation absorbed dose, radiation absorbed dose rate, and chemical composition of the irradiated solutions upon the polymeric materials characteristics are discussed. The required absorbed dose levels to produce the polymeric flocculants are in the range of 0.3 to 9 kGy and 4 kGy to 12 kGy for hydrogels. Some experimental results obtained by testing polymeric flocculants with waste water from food industry are given. Polymeric material processing was developed on a pilot plant level with ALID-7 electron linear accelerator of 5.5 MeV and 0.7 kW, built in the Electron Accelerator Laboratory of the Institute of Atomic Physics, Bucharest. A new facility permitting the application of simultaneous electron beam and microwave irradiation is presently under investigation. Preliminary results demonstrated that some polymeric flocculant characteristics, such as linearity, were improved by simultaneous electron beam and microwave treatment. Also, the absorbed dose levels decreased and intrinsic viscosity increased, respectively, by about two times by this new material processing method.
Electron beam applications in the chemistry of polymers are given, such as the production of acrylamide polymers which are of great interest in the treatment of waste industrial waters. These ...products have unique properties: the required dose is smaller by a factor of 10 to 100 as compared to the dose requirement for other polymeric materials and they are used in aqueous solutions in a concentration of one or two magnitude orders smaller than conventional anorganic flocculants. The acrylamide polymer technologies were first developed on a semi-industrial scale with γ-ray sources and then transferred to the linacs built in the Accelerator Laboratory in the Institute of Atomic Physics. An original feature was included in order to make our linear accelerators using an electron gun of the diode type to render them suitable to obtain programmed beam single shots and pulse trains. It is particularly useful for automatic control of irradiation processing in order to provide the maximum efficiency of the electron beam application. The preliminary results obtained using our electron beam sources make the assumption that the low output power linacs are economically attractive for commercial production of acrylamide type polymers: about 2000 kg per beam kWh.
Creation of Ag
− and Ag
0 centers by irradiation with ionizing radiations has been investigated using NaCl and KCl crystals containing various concentrations of Ag
+ ions and using Ca
2+-codoped ...NaCl:Ag
+ and KCl:Ag
+ crystals. From the absorption spectra, it is observed that Ag
− center perturbed by Ca
2+ ion is also created besides the Ag
− and Ag
0 centers. It is confirmed that Ag
− and Ag
0 centers increase with increasing the concentration of doped Ag
+ ions. It is suggested that there are two kinds of Ag
0
cv
a centers (i.e. Ag
0 accompanied by vacancy at the nearest neighbor) with different site symmetries depending on the location of vacancy.
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