Organotypic human skin culture models constructed with senescent fibroblasts show hallmarks of skin aging.

Skin aging is driven by intrinsic and extrinsic factors impacting on skin functionality with progressive age. One factor of this multifaceted process is cellular senescence, as it has recently been identified to contribute to a declining tissue functionality in old age. In the skin, senescent cells have been found to markedly accumulate with age, and thus might impact directly on skin characteristics. Especially the switch from young, extracellular matrix-building fibroblasts to a senescence-associated secretory phenotype (SASP) could alter the microenvironment in the skin drastically and therefore promote skin aging. In order to study the influence of senescence in human skin, 3D organotypic cultures are a well-suited model system. However, only few "aged" skin- equivalent (SE) models are available, requiring complex and long-term experimental setups. Here, we adapted a previously published full-thickness SE model by seeding increasing ratios of stress-induced premature senescent versus normal fibroblasts into the collagen matrix, terming these SE "senoskin". Immunohistochemistry stainings revealed a shift in the balance between proliferation (Ki67) and differentiation (Keratin 10 and Filaggrin) of keratinocytes within our senoskin equivalents, as well as partial impairment of skin barrier function and changed surface properties. Monitoring of cytokine levels of known SASP factors confirmedly showed an upregulation in 2D cultures of senescent cells and at the time of seeding into the skin equivalent. Surprisingly, we find a blunted response of cytokines in the senoskin equivalent over time during 3D differentiation.

Carbon Microparticles from Organosolv Lignin as Filler for Conducting Poly(Lactic Acid).

Carbon microparticles were produced from organosolv lignin at 2000 °C under argon atmosphere following oxidative thermostabilisation at 250 °C. Scanning electron microscopy, X-ray diffraction, small-angle X-ray scattering, and electro-conductivity measurements revealed that the obtained particles were electrically conductive and were composed of large graphitic domains. Poly(lactic acid) filled with various amounts of lignin-derived microparticles showed higher tensile stiffness increasing with particle load, whereas strength and extensibility decreased. Electric conductivity was measured at filler loads equal to and greater than 25% w/w.

Converse piezoelectric effect in cellulose I revealed by wide-angle X-ray diffraction.

The converse piezoelectric effect in cellulose I was studied by exposing thin pine wood slices to an electric field. Macroscopically, a strong extension of wood was observed in its transverse anatomical direction (grain angle 90 degrees), perpendicular to the direction of the electric field. The same effect, albeit to a lesser extent, was observed for specimens with a 45 degree grain angle, whereas no measurable dimensional change was observed for specimens with grain oriented parallel to the testing direction (0 degree grain angle). The measured extension in the transverse direction was proportional to the intensity of the applied electric field and amounted to 0.0278% on average at a field intensity of 1 MV m(-1), which results in a piezoelectric charge constant of 278 pm V(-1). At the nanoscale, changes in the cellulose crystallites due to the applied electric field were studied by means of wide-angle X-ray diffraction using the same specimens as in macroscopic experiments. Significant radial shifts of the scattering intensity peak attributed to the cellulose 200 crystallographic plane toward smaller scattering angles were observed, while the electric field was applied. These peak shifts were attributed to an increase in the spacing of the 200 crystallographic planes of cellulose I. At an electric field intensity of 1 MV m(-1), a crystallite strain epsilon(perpendicular 200) normal to the 200 reflection plane of 0.2% was estimated from Bragg's law.

Cellulose in never-dried gel oriented by an AC electric field.

Never-dried cellulose gel obtained by slow coagulation from LiCl/N,N-dimethylacetamide (DMAc) solution was exposed to an alternating current electric field. Making use of the birefringence of oriented cellulose and by means of wide-angle X-ray scattering, it was demonstrated that preferred orientation of cellulose molecules parallel to the electric field lines is induced in the cellulose gel. The preferred orientation remained unchanged for several days after storage in water and persisted after drying of the cellulose gel.