Momentum dependent relaxation rate and pseudogap in doped magnetic insulators

The spectral functions and corresponding self energies are calculated within the planar t-t'-J model as relevant to hole-doped cuprates using the exact diagonalization method at finite temperatures, combined with the averaging over twisted boundary conditions. Results show truncated Fermi surface at low doping and t'<0 in the antinodal region while the self energy reveals weakly k- and doping dependent anomalous relaxation rate |\Sigma''(k,\omega)|~ a+b|\omega| for \omega<0, consistent with recent ARPES results, and a pseudogap-generating component of Lorentzian form. The latter is well pronounced at low doping and strongly depends on k and t'.Comment: 5 pages, 5 figure

On Disjoint hypercubes in Fibonacci cubes

The {\em Fibonacci cube} of dimension $n$, denoted as $\Gamma\_n$, is the subgraph of $n$-cube $Q\_n$ induced by vertices with no consecutive 1's. We study the maximum number of disjoint subgraphs in $\Gamma\_n$ isomorphic to $Q\_k$, and denote this number by $q\_k(n)$. We prove several recursive results for $q\_k(n)$, in particular we prove that $q\_{k}(n) = q\_{k-1}(n-2) + q\_{k}(n-3)$. We also prove a closed formula in which $q\_k(n)$ is given in terms of Fibonacci numbers, and finally we give the generating function for the sequence $\{q\_{k}(n)\}\_{n=0}^{ \infty}$

Cellulose Fibres Funcionalised by Chitosan: Characterization and Application

Non

Kraft Lignin/Tannin as a Potential Accelerator of Antioxidant and Antibacterial Properties in an Active Thermoplastic Polyester-Based Multifunctional Material

This research focuses on key priorities in the field of sustainable plastic composites that will lead to a reduction in CO2 pollution and support the EU\u27s goal of becoming carbon neutral by 2050. The main challenge is to develop high-performance polyphenol-reinforced thermoplastic composites, where the use of natural fillers replaces the usual chemical additives with non-toxic ones, not only to improve the final performance but also to increase the desired multifunctionalities (structural, antioxidant, and antibacterial). Therefore, poly (lactic acid) (PLA) composites based on Kraft lignin (KL) and tannin (TANN) were investigated. Two series of PLA composites, PLA-KL and PLA-TANN, which contained natural fillers (0.5%, 1.0%, and 2.5% (w/w)) were prepared by hot melt extrusion. The effects of KL and TANN on the PLA matrices were investigated, especially the surface physicochemical properties, mechanical properties, and antioxidant/antimicrobial activity. The surface physicochemical properties were evaluated by measuring the contact angle (CA), roughness, zeta potential, and nanoindentation. The results of the water contact angle showed that neither KL nor TANN caused a significant change in the wettability, but only a slight increase in the hydrophilicity of the PLA composites. The filler loading, the size of the particles with their available functional groups on the surfaces of the PLA composites, and the interaction between the filler and the PLA polymer depend on the roughness and zeta potential behavior of the PLA-KL and PLA-TANN composites and ultimately improve the surface mechanical properties. The antioxidant properties of the PLA-KL and PLA-TANN composites were determined using the DPPH (2, 2\u27-diphenyl-1-picrylhydrazyl) test. The results show an efficient antioxidant behavior of all PLA-KL and PLA-TANN composites, which increases with the filler content. Finally, the KL- and PLA-based TANN have shown resistance to the Gram-negative bacteria, E. coli, but without a correlation trend between polyphenol filler content and structure

The stiffness of elastomeric surfaces influences the mechanical properties of endothelial cells

Optimal characterization of the mechanical properties of both cells and their surrounding is an issue of major interest. Indeed, cell function and development are strongly influenced by external stimuli. Furthermore, a change in cell mechanics might, in some cases, associate with diseases or malfunctioning. In this work, atomic force microscopy (AFM) was applied to examine the mechanical properties of the silicone elastomer polydimethylsiloxane (PDMS) a common substrate in cell culture. Force spectroscopy analysis was done over different specimens of this elastomeric material containing varying ratios of resin to cross-linker in its structure (5:1, 10:1, 20:1, 30:1 and 50:1), which impacts the final material properties (e.g., stiffness, elasticity). To quantify the mechanical properties of the PDMS, factors as the modulus of Young, the maximum adhesive forces as well as both relaxation amplitudes and times upon constant height contact of the tip (dwell time different of zero) were calculated from the different segments forming the force curves. It is demonstrated that the material stiffness is increased by prior oxygen plasma treatment of the sample, required for hydrophilic switching, contrarily to what observed for its adhesiveness. Subsequent incubation of endothelial HUVEC cells on top of these plasma treated PDMS systems yields minor variation in cell mechanics in comparison to those obtained on a glass reference, on which cells show much higher spreading tendency and, by extension, a remarkable membrane hardening. Thus, surface wettability turns a factor of higher relevance than substrate stiffness inducing variations in the cell mechanics.Comment: manuscript (12 pages, 4 figures, 2 tables), supplementary information (2 pages and 3 figures), the main results of the manuscript are based on a master thesi

Synthesis and Investigation of Modified Silica Coatings for Biotechnology

Mesoporous organic-inorganic hybrid composites on glass substrates were prepared by the sol-gel method for testing the proteins adhesion. Different types of hydrophobic/hydrophilic silica sol-gels were prepared using tetraethoxysilane (TEOS) as starting material and modified with hexamethyldisilazane (HMDS). Sol-gel thin films were successfully prepared with the dip-coating technique on glass surfaces. The coatings surface characteristics were evaluated. The prepared sol-gel derived colloidal silica coatings and modified coatings were characterized by wettability measurements. Also, infrared spectroscopy, atomic force microscope (AFM) assay were used to characterise the surfaces. The coatings of colloidal silica (VT104, water contact angle 17°), polysiloxane sol (VT111, 64°) methyl-modified sols (VT079, 144° and VT112, 47°) with various wettability properties were tested for CaCo-2 cells proliferation. Methylmodified coating VT112 proved to be the best substrate for cell proliferation.Для тестування адгезії білків золь-гель методом приготовано мезопоруваті органо-неорганічні гібридні композити на скляних підкладинках. Різні типи гідрофобних та гідрофільних кремнеземних золів та гелів було приготовано з використанням тетраетоксисилану (ТЕОС) як вихідного матеріалу і модифіковано гексаметилдисилазаном (ГМДС). Тонкі золь-гель плівки було успішно приготовано за допомогою процедури глазурування зануренням на скляних поверхнях. Одержано характеристики поверхонь покриттів. Одержані шляхом золь-гель синтезу покриття – похідні колоїдного кремнезему та модифіковані покриття було охарактеризовано вимірюванням змочуваності. Для характеризації поверхонь було також використано аналіз за допомогою інфрачервоної спектроскопії та атомної силової мікроскопії (АСМ). Покриття з колоїдного кремнезему (VT104, кут змочування водою 17°), полісилоксановий золь (VT111, 64°), метил-модифіковані золі (VT079, 144° та VT112, 47°) з різною змочуваністю було протестовано для розмноження клітин СаСо-2. Метил-модифіковане покриття VT112 виявилось найкращим субстратом для розмноження клітин.Для тестирования адгезии белков золь-гель методом приготовлены мезопористые органо-неорганические гибридные композиты на стеклянных подложках. Разные типы гидрофобных и гидрофильных кремнеземных золей и гелей были приготовлены с использованием тетраэтоксисилана (ТЭОС) как исходного материала и модифицированы гексаметилдисилазаном (ГМДС). Тонкие золь-гель пленки были успешно приготовлены с помощью процедуры глазурирования погружением на стеклянных поверхностях. Получены характеристики поверхностей покрытий. Полученные путем золь-гель синтеза покрытия – производные коллоидного кремнезема и модифицированные покрытия были охарактеризованы измерением смачиваемости. Для характеризации поверхностей был также использован анализ с помощью инфракрасной спектроскопии и атомной силовой микроскопии (АСМ). Покрытия из коллоидного кремнезема (VT104, угол смачивания водой 17°), полисилоксановый золь (VT111, 64°), метил-модифицированные золи (VT079, 144° и VT112, 47°) с разной смачиваемостью были протестированы для размножения клеток СаСо-2. Метилмодифицированное покрытие VT112 оказалось наилучшим субстратом для размножения клеток

Coated chitosan onto gauze to efficient conditions for maintenance of the wound microenvironment

The aim of this work was to evaluate the thermo-physiological comfort and moisture properties of surgical cotton gauze coated with chitosan (CH). Gauze was coated with CH at mass fractions of 0.5, 0.25, 0.125, 0.1, 0.063 wt%. Thermal, moisture management and morphological properties were evaluated. Results indicate that the functionalized medical gauze induces low capilarity, allowing a good degree of moisture and absorption capacity of wound exudates. This biofunctional medical gauze coated with CH0,125 wt% demonstrates to deliver an efficient coating and promote the best conditions for maintenance of the wound microenvironment.Jefferson Souza acknowledge CAPES Foundation, the Ministry of Education of Brazil, Proc. no 8976/13-9 and the Department of Textile Engineering of the University of Minho, Portugal. Andrea Zille acknowledges funding from FCT within the scope of the project POCI-01- 0145-FEDER-007136 and UID/CTM/00264. This work is financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/publishedVersio