The centrifugal spinning of vitamin doped natural gum fibers for skin regeneration

The study investigates the use of fiber carriers, based on biopolymeric gums as potential candidates for cosmetic and dermatological applications, in particular for skin regeneration. Gum arabic (GA), xanthan gum (XA), and gum karaya (GK) were used as the main gum materials for the fibers, which were prepared by centrifugal spinning from an aqueous solution. These solutions of different mass gum ratios were blended with poly (ethylene oxide) (PEO) for better spinnability. Finally, vitamins E and C were added to selected solutions of gums. The resulting fibers were extensively investigated. The morphology and structure of all fibers were investigated by scanning electron microscopy and Fourier transformed infrared spectroscopy. Most importantly, they were characterized by the release of vitamin E loaded in the fibers using UV-VIS spectroscopy. The presentation will show that the newly prepared fibers from GA and PEO represent a very promising material for cosmetic and dermatologic applications

Aromatic copolymers with increased solubility

Práce se zabývá přípravou aromatických kopolyamidů se zvýšenou rozpustností z prekurzorů obsahujících difenyetherovou komponentu. Byl připraven aromatický kopolyamid z prekurzoru připraveného z 4-nitro-3'-aminodifenyletheru a p-nitrobenzoylchloridu jeho čištěním a redukcí na N-3-(4-aminofenixyfenyl)-4'-aminobenzenkarboxamid. Je popsán postup čištění a odvodnění prekuzoru. Je diskutována jeho stabilita, možnost použití pro malotonážní přípravu speciálních aramidů se zvýšenou rozpustností. Byl připraven roztok kopolyamidu v DMAA, prověřeny jeho reologické vlastnosti a pozorována jeho vláknotvornost.Dokončená práce s úspěšnou obhajobo

Hydrodechlorination of Different Chloroaromatic Compounds at Room Temperature and Ambient Pressure—Differences in Reactivity of Cu- and Ni-Based Al Alloys in an Alkaline Aqueous Solution

It is well known that the hydrodechlorination (HDC) of chlorinated aromatic contaminants in aqueous effluents enables a significant increase in biodegradability. HDC consumes a low quantity of reactants producing corresponding non-chlorinated and much more biodegradable organic compounds. Two commonly used precious metals free Al alloys (Raney Al-Ni and Devarda’s Al-Cu-Zn) were compared in reductive action in an alkaline aqueous solution. Raney Al-Ni alloy was examined as a universal and extremely effective HDC agent in a diluted aqueous NaOH solution. The robustness of Raney Al-Ni activity is illustrated in the case of HDC of polychlorinated aromatic compounds mixture in actual waste water. In contrast, Devarda’s Al-Cu-Zn alloy was approved as much less active for HDC of the tested chlorinated aromatic compounds, but with a surprisingly high selectivity on cleavage of C-Cl bonds in the meta and sometimes the ortho position in chlorinated aniline and sometimes chlorinated phenol structures. The reaction of both tested alloys with chlorinated aromatic compounds in the aqueous NaOH solution is accompanied by dissolution of aluminum. Dissolved Al in the alkaline HDC reaction mixture is very useful for subsequent treatment of HDC products by coagulation and flocculation of Al(OH)3 caused by simple neutralization of the alkaline aqueous phase after the HDC reaction

Strukturní modulace amorfních 2D materiálů na bázi oxidu wolframu v magnetronovém naprašování

2D oxide materials have gained tremendous attention in the applications. Herein, a synthesis route of 2D WO3 materials via magnetron sputtering is reported. A deposition between 2D monolayers and thin film structure are accomplished according to the temperature of substrate. And 2D monolayers are only formed on a cooled substrate. Ag doping helps to exfoliate 2D WO3 into freestanding monolayers, in which the thickness of 2D monolayer is only approximate to 3 nm. The ultralarge size of 2D WO3 shows unique features from the traditional 2D material. Resistive switching device and photocatalysis are discussed as examples of application. There is a clear intermediate resistance state in the device with 2D structure. And the failure of resistive switching device is closely related with the 2D structure of WO3. In the application of photocatalysis, an improved two-step exfoliation, achieving a stack of WO3 monolayers with a large internal volume, is utilized. The enhancements of photocatalysis are obtained with 2D WO3 after exfoliation.2D oxidové materiály si v aplikacích získaly obrovskou pozornost. Zde je popsána cesta syntézy 2D W03 materiálů prostřednictvím magnetronového naprašování. Depozice mezi 2D monovrstvami a strukturou tenkého filmu se provádí podle teploty substrátu. A 2D monovrstvy se tvoří pouze na chlazeném substrátu. Ag doping pomáhá exfoliovat 2D WO3 do volně stojících monovrstev, ve kterých je tloušťka 2D monovrstvy cca ≈3 nm. Příkladem použití vrstev je odporové spínání a fotokatalýza. V zařízení s 2D strukturou je jasný stav středního odporu. Při aplikaci fotokatalýzy se využívá vylepšené dvoukrokové exfoliace, čímž se dosáhne slohy monovrstev WO3 s velkým vnitřním objemem. Zvýšení účinnosti fotokatalýzy se dosáhne pomocí 2D WO3 po exfoliaci

Synthesis of centrifugally spun polyacrylonitrile-carbon fibers

This work demonstrates the carbonization of centrifugally spun polyacrylonitrile (PAN) fibers. Initially, the optimal centrifugal spinning conditions for producing homogeneous PAN fibers were identified. Second, the process continued by stabilization and carbonization of PAN to ensure a pure carbonaceous fiber material by eliminating all non-carbonaceous matter. The spun PAN fibers were stabilized at 240 °C in air at a heating rate of 1 °C/min, then carbonized between 600 and 1200 °C in argon at 5 °C/min. After carbonization, the fibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Raman spectroscopy (RS). The SEM results showed that by increasing the carbonization temperature, the prolonged elimination of other functional groups resulted in the formation of thinner carbon fibers. FTIR spectra of PAN fibers revealed that the peaks associated with C≡N bonds were substantially reduced and C–H bonds were eliminated in the fibers during the stabilization. These reductions are attributed to the cyclization of nitrile groups and the stabilizing process, and increasing carbonization temperatures resulted in flatter FTIR curves, supporting the findings. According to XRD, the structure of PAN was disturbed, as desired, and carbonization led to the formation of broad bumps resulting from amorphous carbon. Raman investigations found that increasing the carbonization temperature from 600 to 1200 °C resulted in no significant R values, suggesting that all fibers had no structural ordering. The study results could be used in many other areas, such as the fabrication of electrodes, supporting catalytic reactions, filter media, and energy

Cu-katalyzovaná hydrodehalogenace bromovaných aromatických polutantů ve vodném roztoku

The catalytic effect of copper in Devarda's Al-Cu-Zn alloy (Dev. alloy) and sole metallic copper, copper salts and copper oxides in the coaction of NaBH4 within the hydrodehalogenation (HDH) of polybrominated phenols, such as the herbicide Bromoxynil in alkaline aqueous solution has been investigated. Namely, the hydrodebromination (HDB) activity of Dev. alloy/NaOH system has been compared to heterogeneous Cu-based catalysts using NaBH4 as a reductant. Differences in the solid-state structures of used Cu-based heterogeneous catalysts after the mentioned HDB process have been studied using the powder XRD and SEM techniques. It was found that some of the used copper-based catalysts are reusable and reasonably effective even at room temperature. Efficiency of the most promising copper-based reduction systems (Dev. alloy/NaOH and Cu-based catalysts/NaBH4) have been successfully tested within the HDB of industrially important brominated flame retardant tetrabromobisphenol A (TBBPA). Dev. alloy/NaOH and Cu-based catalyst generated in-situ within the CuSO4/NaBH4 produced were recognized as the most active HDB agents for complete debromination of both BRX and TBBPA.Byl testován vliv mědi, hliníku a zinku, které tvoří Devardovu slitinu, na účinnost hydrodebromace. Vliv oxidů mědi byl testován za spolupůsobení NaBH4. jako modelová sloučenina byl použit herbicid Bromoxynil

2D kovový wolfram

2D metallic material is an important group member in 2D material family. Many applications have been applied in the catalysis and devices. In this paper, we present a novel method to prepare the tungsten 2D material, which is simple and powerful. The W thin film is deposited via magnetron sputtering. As-deposited tungsten thin film is able to be exfoliated with wet and dry methods. We show a clear layered structure of the tungsten thin film from the cross sectional view. Via the exfoliation, an large area 2D tungsten monolayer is obtained. After oxidation, the 2D material shows potentials in electric signal transport.2D kovový materiál je důležitým členem skupiny ve skupině 2D materiálů. Mnoho aplikací bylo použito v katalýze a v dalších zařízeních. V tomto příspěvku představujeme novou metodu přípravy wolframového 2D materiálu, která je jednoduchá a výkonná. Tenký film W je nanášen magnetronovým rozprašováním. Takto nanesený tenký film wolframu lze odlupovat mokrými a suchými metodami. V řezu vrstvou presentujeme jasnou vrstvenou strukturu wolframového tenkého filmu. Prostřednictvím exfoliace se získá velkoplošná 2D monovrstva wolframu. Po oxidaci ukazuje je 2D materiál slibný v přenosu elektrického signálu