Flexible CO₂ sensor architecture with selective nitrogen functionalities by one-step laser-induced conversion of versatile organic ink

Nitrogen-doped carbons (NC) are a class of sustainable materials for selective CO2 adsorption. We introduce a versatile concept to fabricate flexible NC-based sensor architectures for room-temperature sensing of CO2 in a one-step laser conversion of primary coatings cast from abundant precursors. By the unidirectional energy impact in conjunction with depth-dependent attenuation of the laser beam, a layered sensor heterostructure with porous transducer and active sensor layer is formed. Comprehensive microscopic and spectroscopic cross-sectional analyses confirm the preservation of a high content of imidazolic nitrogen in the sensor. The performance was optimized in terms of material morphology, chemical composition, and surface chemistry to achieve a linear relative resistive response of up to ∆R/R0 = -14.3% (10% of CO2). Thermodynamic analysis yields ΔadsH values of -35.6 kJ·mol-1 and 34.1 kJ·mol-1 for H2O and CO2, respectively. The sensor is operable even in humid environments (e.g., ∆R/R0,RH=80% = 0.53%) and shows good performance upon strong mechanical deformation

Synthesis of organic inorganic hybrids based on the conjugated polymer P3HT and mesoporous silicon

Organic inorganic hybrids are a class of functional materials that combine favorable properties of their constituents to achieve an overall improved performance for a wide range of applications. This article presents the synthesis route for P3HT porous silicon hybrids for thermoelectric applications. The conjugated polymer P3HT is incorporated into the porous silicon matrix by means of melt infiltration. Gravimetry, sorption isotherms and energy dispersive X ray spectroscopy EDX mapping indicate that the organic molecules occupy more than 50 of the void space in the inorganic host. We demonstrate that subsequent diffusion based doping of the confined polymer in a FeCl3 solution increases the electrical conductivity of the hybrid by five orders of magnitude compared to the empty porous silicon hos

Nitric Oxide Mediates Stretch-Induced Ca2+ Release via Activation of Phosphatidylinositol 3-Kinase-Akt Pathway in Smooth Muscle

Hollow smooth muscle organs such as the bladder undergo significant changes in wall tension associated with filling and distension, with attendant changes in muscle tone. Our previous study indicated that stretch induces Ca(2+) release occurs in the form of Ca(2+) sparks and Ca(2+) waves in urinary bladder myocytes. While, the mechanism underlying stretch-induced Ca2+ release in smooth muscle is unknown.We examined the transduction mechanism linking cell stretch to Ca(2+) release. The probability and frequency of Ca(2+) sparks induced by stretch were closely related to the extent of cell extension and the time that the stretch was maintained. Experiments in tissues and single myocytes indicated that mechanical stretch significantly increases the production of nitric oxide (NO) and the amplitude and duration of muscle contraction. Stretch-induced Ca(2+) sparks and contractility increases were abrogated by the NO inhibitor L-NAME and were also absent in eNOS knockout mice. Furthermore, exposure of eNOS null mice to exogenously generated NO induced Ca(2+) sparks. The soluble guanylyl cyclase inhibitor ODQ did not inhibit SICR, but this process was effectively blocked by the PI3 kinase inhibitors LY494002 and wortmannin; the phosphorylation of Akt and eNOS were up-regulated by 204+/-28.6% and 258+/-36.8% by stretch, respectively. Moreover, stretch significantly increased the eNOS protein expression level.Taking together, these results suggest that stretch-induced Ca2+ release is NO dependent, resulting from the activation of PI3K/Akt pathway in smooth muscle

Acute mountain sickness.

Acute mountain sickness (AMS) is a clinical syndrome occurring in otherwise healthy normal individuals who ascend rapidly to high altitude. Symptoms develop over a period ofa few hours or days. The usual symptoms include headache, anorexia, nausea, vomiting, lethargy, unsteadiness of gait, undue dyspnoea on moderate exertion and interrupted sleep. AMS is unrelated to physical fitness, sex or age except that young children over two years of age are unduly susceptible. One of the striking features ofAMS is the wide variation in individual susceptibility which is to some extent consistent. Some subjects never experience symptoms at any altitude while others have repeated attacks on ascending to quite modest altitudes. Rapid ascent to altitudes of 2500 to 3000m will produce symptoms in some subjects while after ascent over 23 days to 5000m most subjects will be affected, some to a marked degree. In general, the more rapid the ascent, the higher the altitude reached and the greater the physical exertion involved, the more severe AMS will be. Ifthe subjects stay at the altitude reached there is a tendency for acclimatization to occur and symptoms to remit over 1-7 days

Characterization and modeling of the temperature dependent thermal conductivity in sintered porous silicon aluminum nanomaterials

Nanostructured silicon and silicon aluminum compounds are synthesized by a novel synthesis strategy based on spark plasma sintering SPS of silicon nanopowder, mesoporous silicon pSi , and aluminum nanopowder. The interplay of metal assisted crystallization and inherent porosity is exploited to largely suppress thermal conductivity. Morphology and temperature dependent thermal conductivity studies allow us to elucidate the impact of porosity and nanostructure on the macroscopic heat transport. Analytic electron microscopy along with quantitative image analysis is applied to characterize the sample morphology in terms of domain size and interpore distance distributions. We demonstrate that nanostructured domains and high porosity can be maintained in densified mesoporous silicon samples. In contrast, strong grain growth is observed for sintered nanopowders under similar sintering conditions. We observe that aluminum agglomerations induce local grain growth, while aluminum diffusion is observed in porous silicon and dispersed nanoparticles. A detailed analysis of the measured thermal conductivity between 300 and 773 K allows us to distinguish the effect of reduced thermal conductivity caused by porosity from the reduction induced by phonon scattering at nanosized domains. With a modified Landauer Lundstrom approach the relative thermal conductivity and the scattering length are extracted. The relative thermal conductivity confirms the applicability of Kirkpatrick s effective medium theory. The extracted scattering lengths are in excellent agreement with the harmonic mean of log normal distributed domain sizes and the interpore distances combined by Matthiessen s rul

Phonons in highly crystalline mesoporous silicon The absence of phonon softening upon structuring silicon on sub 10 nanometer length scales

This article presents inelastic thermal neutron scattering experiments probing the phonon dispersion in mesoporous silicon with pores 8 nm across. Scattering studies reveal the energy momentum relation for transverse and longitudinal phonons along the high symmetry directions amp; 120548; amp; 119871;, amp; 120548; amp; 119870; and amp; 120548; amp; 119883; in the Brillouin zone. The dispersion up to phonon energies of 35 meV unambiguously proves that the phonon group velocities in highly crystalline silicon are not modified by nanostructuring down to sub 10 nanometer length scales. On these length scales, there is apparently no effect of structuring on the elastic moduli of mesoporous silicon. No evidence can be found for phonon softening in topologically complex, geometrically disordered mesoporous silicon putting it in contrast to silicon nanotubes and nanoribbon