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Wyświetlanie 1-4 z 4
Tytuł:
Biomediated production of structurally diverse poly(hydroxyalkanoates) from surplus streams of the animal processing industry
Bioprodukcja zróżnicowanych strukturalnie poli(hydroksyalkanianów) z produktów ubocznych przemysłu mięsnego
Autorzy:
Koller, M.
Braunegg, G.
Powiązania:
https://bibliotekanauki.pl/articles/945849.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
animal processing
biodiesel
biopolymers
crude glycerol phase
poly(hydroxyalkanoates) (PHA)
process design
saturated fatty acid esters
surplus materials
biopolimery
surowa faza glicerynowa
poly(hydroksyalkaniany) (PHA)
nasycone kwasy tłuszczowe
produkty uboczne
Opis:
For commercial success, enhanced poly(hydroxyalkanoate) (PHA) production must address both material performance and economic aspects. Conventional PHA production consumes expensive feedstocks dedicated to nutrition. Switching to carbon-rich (agro)industrial side-streams alleviates industrial disposal problems, preserves food resources, and can be economically superior. Processes developed in the recently performed EU-FP7 project ANIMPOL resort to lipid-rich surplus streams from slaughterhouses and the rendering industry; these materials undergo chemical transformation to crude glycerol phase (CGP) and biodiesel. The saturated biodiesel share (SFAE) counteracts its applicability as abiofuel but, in addition to CGP, can be converted biotechnologically to PHAs. Depending on the applied microbial production strain and the selected carbon source (SFAE or CGP), thermoplastic short chain length PHA (scl-PHA), as well as elastomeric to latex-like medium chain length PHA (mcl-PHA), can be produced from these inexpensive feed stocks. The article illustrates the biotechnological conversion of animal-based CGP and SFAE towards poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), respectively, by Cupriavidus necator strain DSM 545. SFAE conversion towards mcl-PHAs consisting of various saturated and unsaturated building blocks by two pseudomonades, Ps. citronellolis DSM 50332 and Ps. chlororaphis DSM 50083, are also shown. Together with the kinetics of the bioprocesses, the results from the characterization of isolated samples of these structurally diverse biopolyesters are compared; data demonstrate the high versatility of biopolymer properties making them applicable in various fields of the plastic market. In addition to the need for inexpensive carbon feed stocks, the article points to further hot spots of the PHA-production chain that must be considered in order to lower the overall PHA production costs, and to enhance product quality. The benefits arising from multistage continuous cultivation production set-ups, namely high-throughput production of PHA of predefined composition and constant quality, are especially discussed. Finally, contemporary approaches towards environmentally and ecologically sustainable PHA recovery from biomass are summarized.
Artykuł stanowi przegląd literatury dotyczącej biosyntezy poli(hydroksyalkanianów) (PHA) z wykorzystaniem jako surowców odpadów z przemysłu rolno-spożywczego. Omówiono wyniki uzyskane podczas realizacji projektu ANIMPOL (7. PR UE), w którym jako surowiec do syntezy PHA stosowano bogate w tłuszcze produkty uboczne z rzeźni i zakładów utylizacji odpadów zwierzęcych, przekształcone chemicznie w surową fazę glicerynową (CGP) i biodiesel (estry nasyconych kwasów tłuszczowych, SFAE). Zależnie od użytego szczepu bakterii oraz źródła węgla (SFAE lub CGP) otrzymano termoplastyczne krótkołańcuchowe PHA (scl-PHA) lub średniołańcuchowe PHA (mcl-PHA). Zaprezentowano biotechnologiczną konwersję CGP iSFAE pochodzenia zwierzęcego do poli(3-hydroksymaślanu) (PHB) i poli(3-hydroksymaślanu-co-3-hydroksywalerianu) (PHBV) za pomocą szczepu bakteryjnego Cupriavidus necator strain DSM 545, syntezę mcl-PHA zawierających nasycone i nienasycone elementy strukturalne za pomocą bakterii z rodzaju Pseudomonas (Ps. citronellolis DSM 50332 i Ps. chlororaphis DSM 50083). Omówiono kinetykę bioprocesów oraz charakterystykę otrzymanych biopoliestrów, przedyskutowano elementy cyklu produkcyjnego PHA kluczowe z punktu widzenia zmniejszenia kosztów i poprawy jakości produktów oraz korzyści wynikające z zastosowania układów ciągłej wielostopniowej hodowli w wysokowydajnej produkcji PHA o założonym składzie i stabilnej jakości. Omówiono też nowe metody odzyskiwania PHA z biomasy, zgodne z wymaganiami ochrony środowiska.
Źródło:
Polimery; 2015, 60, 5; 298-308
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the nature of silver ions in complex media
Autorzy:
Loza, K.
Diendorf, J.
Sengstock, C.
Koller, M.
Epple, M.
Powiązania:
https://bibliotekanauki.pl/articles/286036.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
silver ions
biocides
biomaterials
Opis:
Antimicrobial biocides are commonly used to present the growth of bacteria on surfaces and within materials. They are typically added in small quantities to many applications to prevent bacterial growth on the treated object. Silver is increasingly used in many applications due to the aim to replace organic chemical agents by inorganic additives. Examples of applications are bacteriostatic water filters for household use or swimming pool algaecides and numerous devices, ranging from consumer commodities like mobile phones, refrigerators, and clothes to medical devices like catheters, implant surfaces, and plasters. To meet the diversity of application types, many different forms of silver compounds have been developed to serve this market. In particular, there is little information on the types of transformations that silver nanoparticles will undoubtedly undergo in real, complex environments during long-term aging, and the impact of these transformations on their distribution in the environment, bioavailability, and toxicity potential. The biocidal action results from the interaction of silver ions with bacteria. The most potent compounds for a high silver release are soluble silver salts like silver nitrate or silver acetate. These are fully water soluble with a high silver ion release rate. Therefore they are often used as control in cell experiments to elucidate the biological effect of silver nanoparticles. However, in the case of free silver nanoparticles the interactions can be more complex and catalytic reactions on the particle surface which depend on the size and shape of the nanoparticles can render the system very complex. If AgNO3 is used as control, it is tacitly assumed, that the free silver ion concentration is the same as that in the added AgNO3. This obviously cannot be true because of the presence of a whole set of proteins, biomolecules and inorganic ions like Cl- and H2PO4- in the biological medium. These will react with the silver ions in one or the other way. We report on experiments on the behaviour of silver ions in biologically relevant concentrations in different media, from physiological salt solution over phosphate-buffered saline solution to cell culture media. For dissolution and immersion experiments PVP-coated silver nanoparticles were synthesized by reduction with glucose in the presence of PVP. The final silver concentration in all dispersions was determined by atomic absorption spectroscopy. The dissolution of silver nanoparticles was followed in long-term experiments out of a dialysis tube which was permeable only for silver ions. In case of immersion experiments, the nanoparticles and all precipitates were isolated by ultracentrifugation, redispersed in pure water and again subjected to ultracentrifugation. The particles were analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray powder diffraction. The dissolution requires the presence of dissolved oxygen. If no oxygen is present, only a very small fraction of silver is dissolved, possibly by traces of oxygen in the experimental setup. An oxidizing agent like H2O2 clearly enhances the dissolution. The presence of NaCl, either in pure form or as PBS, strongly slows down the dissolution, probably due to silver chloride formation. Cysteine has a clearly inhibiting effect with almost no dissolution of the silver nanoparticles whereas glucose has a decelerating effect but leads to a similar final dissolved fraction. This suggests that cysteine adsorbs onto the silver nanoparticle surface with its thiol group and prevents the oxidation. In contrast, glucose slows down the dissolution, but clearly did not prevent the oxidation on a longer time scale. We have extended the studies by mixing silver nanoparticle dispersions with different media of increasingly biological nature. The solutions/dispersions were stirred for equilibration and then subjected to ultracentrifugation. All precipitates and nanoparticles were isolated by this way and then analyzed. The results show that both initially present silver ions and released silver ions are mainly precipitated as AgCl if chloride is present. Only in the absence of chloride, glucose is able to reduce Ag+ to Ag0. The initially present silver nanoparticles were recovered in all cases. Silver phosphate was not observed in any case, probably due to the moderate pH (around 7) at which phosphate is mostly protonated to hydrogen phosphate and dihydrogen phosphate. We can conclude that released silver ions precipitate mostly as AgCl in biological media, and that most cell culture studies where silver ions are used as control are in fact studying the effect of colloidal silver chloride on the cells. To prove this assumption, human mesenchymal stem cells (hMSC) were cultured in the presence of silver chloride nanoparticles (diameter 120 nm), and the viability of the cells was analyzed by fluorescence microscopy. In general, we clearly observed that pure silver nanoparticles have lower toxicity to hMSC compared to silver chloride nanoparticles with a comparable total silver dose. Silver acetate in the biological medium had a comparable toxicity to hMSC compared to silver chloride nanoparticles with the same total silver dose.
Źródło:
Engineering of Biomaterials; 2014, 17, no. 128-129; 80
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anisotropic Elastic and Acoustic Properties of Bulk Graphene Nanoplatelets Consolidated by Spark Plasma Sintering
Autorzy:
Koller, M.
Seiner, H.
Landa, M.
Nieto, A.
Agarwal, A.
Powiązania:
https://bibliotekanauki.pl/articles/1402122.pdf
Data publikacji:
2015-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.35.Cg
81.40.Jj
81.05.ue
81.20.Ev
Opis:
Elastic anisotropy and acoustic attenuation in bulk material consisting of consolidated graphene nanoplatelets are studied. The material was prepared by spark plasma sintering, and exhibits highly anisotropic microstructure with the graphene nanoplatelets oriented perpendicular to the spark plasma sintering compression axis. The complete tensor of elastic constants is obtained using a combination of two ultrasonic methods: the through-transmission method and the resonant ultrasound spectroscopy. It is shown that the examined material exhibits very strong anisotropy both in the elasticity (the Young moduli in directions parallel to the graphene nanoplatelets and perpendicular to them differ by more than 20 times) and in the attenuation, where the dissipative effect of the internal friction in the graphene nanoplatelets combines with strong scattering losses due to the porosity. The results are compared with those obtained for ceramic-matrix/graphene nanoplatelet composites by the same ultrasonic methods.
Źródło:
Acta Physica Polonica A; 2015, 128, 4; 670-674
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silicosis in Switzerland
Autorzy:
Koller, Michael F.
Scholz, Stefan M.
Pletscher, Claudia
Miedinger, David
Powiązania:
https://bibliotekanauki.pl/articles/2162017.pdf
Data publikacji:
2018-10-23
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
lung cancer
silicosis
quartz
occupational exposure limit
crystalline silica
Switzerland
Opis:
Objectives The correlation between quartz dust concentrations in the Swiss enterprises and the incidence of silicosis and other related diseases acknowledged as occupational diseases (OD) was investigated. Material and Methods Quartz dust concentrations were obtained from Suva’s databases of occupational health surveillance measurements between 2005 and 2014. Information on quartz dust-related diseases was from medical dossiers of workers with OD acknowledged by Suva between 2005 and 2014. Results The median quartz dust concentration of the 2579 measurements between 2005 and 2014 was 0.09 mg/m³ (alveolar fraction). Out of all measurements, 28% were above the Swiss occupational exposure limit (OEL) of 0.15 mg/m³ (alveolar fraction). One hundred eighty-one individuals suffered from acknowledged quartz dust-related disease (179 silicosis and 2 chronic obstructive pulmonary disease (COPD)). Additionally, 8 out of these workers were diagnosed with lung cancer and 55 with COPD of a non-specified cause. Out of all workers, 46% were exposed to silica dust for the first time before 1975 when the current Swiss OEL was introduced. Out of the foreign workers, 63% began to work abroad, during which they could have at least partly acquired their silicosis. Out of all workers, 75% were ever-smokers. Conclusions The incidence of silicosis decreased drastically from approximately 300 cases/year in the 1970s to fewer than 20 cases/year 20 years ago. Several findings of this study that could help to interpret the ongoing occurrence of the disease include excessive exposure in or outside of Switzerland in former or current times, vulnerability to the development of silicosis due to cigarette smoke, or poor compliance with wearing breathing masks. Int J Occup Med Environ Health 2018;31(5):659–676
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2018, 31, 5; 659-676
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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