New pathways for sustainable terpene materials from wood

Polymers play an essential role in everyday life as materials in automotive, packaging and electronics to compounds in medicine. Nevertheless, the finite supply of fossil fuels and lacking biodegradability of most synthetic polymers leads to an increased need for the development of more sustainable materials from renewable sources. The use of renewable natural products from forestry, especially hemicellulose and terpenes,1 offers a highly versatile platform for green building blocks. By using Nature’s own biofunctionalizations, enzymes can be used as green catalysts for the valorization of abundant terpenes from pine wood extractives. Enzymatic biotransformations enable mild processes for “activating” inert molecular building blocks to afford renewable monomers. By combining in vitro synthetic biology and polymer chemistry, we have generated a new bio based polymer starting from, a naturally abundantterpene found in wood. Specifically, acrylation of the terpene Sobrerol, which can be achieved§ both enzymatically and by using traditional chemistry, constituted a suitable synthon for Atom Transfer Radical Polymerization (ATRP); a common and widely used, controlled polymerization technique. Furthermore, we demonstrate that sobrerol can be generated from other abundant monoterpenes using P450-based biocatalysis. Please click Additional Files below to see the full abstract

Reactive magnetron sputtering of tungsten target in krypton/trimethylboron atmosphere

W-B-C films were deposited on Si(100) substrates held at elevated temperature by reactive sputtering from a W target in Kr/trimethylboron (TMB) plasmas. Quantitative analysis by X-ray photoelectron spectroscopy (XPS) shows that the films are W-rich between ~ 73 and ~ 93 at.% W. The highest metal content is detected in the film deposited with 1 sccm TMB. The C and B concentrations increase with increasing TMB flow to a maximum of ~18 and ~7 at.%, respectively, while the O content remains nearly constant at 2-3 at.%. Chemical bonding structure analysis performed after samples sputter-cleaning reveals C-W and B-W bonding and no detectable W-O bonds. During film growth with 5 sccm TMB and 500 oC or with 10 sccm TMB and 300-600 oC thin film X-ray diffraction shows the formation of cubic 100-oriented WC1-x with a possible solid solution of B. Lower flows and lower growth temperatures favor growth of W and W2C, respectively. Depositions at 700 and 800 oC result in the formation of WSi2 due to a reaction with the substrate. At 900 oC, XPS analysis shows ~96 at.% Si in the film due to Si interdiffusion. Scanning electron microscopy images reveal a fine-grained microstructure for the deposited WC1-x films. Nanoindentation gives hardness values in the range from ~23 to ~31 GPa and reduced elastic moduli between ~220 and 280 GPa in the films deposited at temperatures lower than 600 oC. At higher growth temperatures the hardness decreases by a factor of 3 to 4 following the formation of WSi2 at 700-800 oC and Si-rich surface at 900 oC.Comment: 14 pages, 8 figure

Оптимизация преподавания темы "Диагностика и лечение атеросклероза" на факультете повышения квалификации врачей

ФАКУЛЬТЕТЫ ПОВЫШЕНИЯ КВАЛИФИКАЦИИПОВЫШЕНИЕ КВАЛИФИКАЦИИОБРАЗОВАНИЕ МЕДИЦИНСКОЕ, ПОВЫШЕНИЕ КВАЛИФИКАЦИИПРЕПОДАВАНИЕМЕТОДИКА ПРЕПОДАВАНИЯОБРАЗОВАТЕЛЬНЫЕ ТЕХНОЛОГИ

Panel Three: The Roles of Juries and the Press in the Modern Judicial System

Reactive sputtering by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a Zr target in Ar/H-2 plasmas was employed to deposit Zr-H films on Si(100) substrates, and with H content up to 61 at.% and O contents typically below 0.2 at.% as determined by elastic recoil detection analysis. X-ray photoelectron spectroscopy reveals a chemical shift of similar to 0.7 eV to higher binding energies for the Zr-H films compared to pure Zr films, consistent with a charge transfer from Zr to H in a zirconium hydride. X-ray diffraction shows that the films are single-phase delta-ZrH2 (CaF2 type structure) at H content greater thansimilar to 55 at.% and pole figure measurements give a 111 preferred orientation for these films. Scanning electron microscopy cross-section images show a glasslike microstructure for the HiPIMS films, while the DCMS films are columnar. Nanoindentation yield hardness values of 5.5-7 GPa for the delta-ZrH2 films that is slightly harder than the similar to 5 GPa determined for Zr films and with coefficients of friction in the range of 0.12-0.18 to compare with the range of 0.4-0.6 obtained for Zr films. Wear resistance testing show that phase-pure delta-ZrH2 films deposited by HiPIMS exhibit up to 50 times lower wear rate compared to those containing a secondary Zr phase. Four-point probe measurements give resistivity values in the range of similar to 100-120 mu Omega cm for the delta-ZrH2 films, which is slightly higher compared to Zr films with values in the range 70-80 mu Omega cm

Fucoidan-Mimetic Glycopolymers : Synthesis and Biomedical Applications

The marine polysaccharide fucoidan has demonstrated several interesting biological properties, for instance being antiviral, anticoagulant, anti-inflammatory, anticancer, and platelet activating. Many of these properties are desirable for various biomedical applications. Yet, there are few reports on fucoidan being used in such applications. The reasons for this are primarily the heterogeneity and low structural reproducibility of fucoidan. This thesis describes the synthesis of polymers with pendant saccharides bearing the key structural features of fucoidan. These glycopolymers were synthesized via different radical polymerization techniques yielding polymers of different chain lengths and dispersity. These glycopolymers showed antiviral and platelet activating properties similar to those of natural fucoidan, thus making them fucoidan-mimetic glycopolymers. However, compared to fucoidan from natural sources, the fucoidan-mimetic glycopolymers had homogeneous and reproducible structures making them suitable for biomedical applications. Further studies demonstrated that platelet activation, caused by these glycopolymers, showed dose-response curves almost identical to fucoidan. The platelet activation was induced via intracellular signaling and caused platelet surface changes similar to those of fucoidan. Fucoidan-mimetic glycopolymers can therefore be used as unique biomolecular tools for studying the molecular and cellular responses of human platelets. Fucoidan-mimetic glycopolymers generally assert their antiviral activity by blocking viral entry to host cells, thus inhibiting spreading of the viral infection but not acting virucidal, i.e. not killing the viruses. Introduction of hydrophobic groups to the polymer’s chain ends improved the antiviral properties significantly and is an important step towards yielding glycopolymers with virucidal properties. The fucoidan-mimetic glycopolymers were also applied as capping agents when synthesizing gold nanoparticles. These fucoidan-mimetic glycopolymer coated gold nanoparticles showed improved colloidal stability compared to uncapped gold nanoparticles. Furthermore, the nanoparticles also demonstrated selective cytotoxicity against a human colon cancer cell line over fibroblast cells

Atom probe tomography field evaporation characteristics and compositional corrections of ZrB2

The microstructure of stoichiometric ZrB2.0 and B over-stoichiometric ZrB2.5 thin films has been studied using atom probe tomography (APT), X-ray diffraction, and transmission electron microscopy. Both films consist of columnar ZrB2 grains with AlB2-type crystal structure. The narrow stoichiometry range of ZrB2 results in the presence of separate disordered B-rich boundaries even in ZrB2.0. At higher average B content, specifically ZrB2.5, the formation of a continuous network around the sides of the ZrB2 columns is promoted. In addition, the APT field evaporation characteristics of ZrB2 and its influence on the measured local composition has been studied and compared to the average composition from elastic recoil detection analysis (ERDA). Differences in the measured average compositions of the two techniques are explained by the APT detector dead-time/space. A new pile-up pairs correction procedure based on co-evaporation correlation data was thus employed here for the APT data and compared with the 10B-method (the B equivalence of the 13C-method), as well as the combination of both methods. In ZrB2.0, all of the applied compositional correction methods were found to reduce the compositional difference when appropriate isotopic abundances were used. In ZrB2.5, the inhomogeneity of the film likely increased the local APT composition to such an extent that even conservative correction procedures overestimated the B content compared to the ERDA reference. The strengths of the pile-up pairs correction compared the 10B and the combined methods are higher precision, due to it being less dependent on the accuracy of estimated isotopic abundances, and that the correction itself is not dependent on careful background correction of the mass spectrum

beta-Ta and alpha-Cr thin films deposited by high power impulse magnetron sputtering and direct current magnetron sputtering in hydrogen containing plasmas

Thin films of beta-Ta and alpha-Cr were deposited on Si(1 0 0) and 1000 angstrom SiO2/Si(1 0 0), by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (dcMS) in hydrogen-containing plasmas. The films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction, scanning electron microscopy, elastic recoil detection analysis, and four-point probe measurements. The results showed that 001-oriented beta-Ta films containing up to similar to 8 at% hydrogen were obtained with HiPIMS, albeit with no chemical shift evident in XPS. The 110 oriented alpha-Cr films display a hydrogen content less than the detection limit of 1 at%, but H-2 favors the growth of high-purity films for both metals. The beta-Ta films deposited with dcMS are columnar, which seems independent of H-2 presence in the plasma, while the films grown by HIPIMS are more fine-grained. The latter type of microstructure was present for the alpha-Cr films and found to be independent on choice of technique or hydrogen in the plasma. The beta-Ta films show a resistivity of similar to 140-180 mu Omega cm, while alpha-Cr films exhibit values around 30 mu Omega cm; the lowest values obtained for films deposited by HiPIMS and with hydrogen in the plasma for both metals