A Method for forcasting Salinity Process in Seawater-Intruded Rivers

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Cell contraction induces long-ranged stress stiffening in the extracellular matrix

Animal cells in tissues are supported by biopolymer matrices, which typically exhibit highly nonlinear mechanical properties. While the linear elasticity of the matrix can significantly impact cell mechanics and functionality, it remains largely unknown how cells, in turn, affect the nonlinear mechanics of their surrounding matrix. Here we show that living contractile cells are able to generate a massive stiffness gradient in three distinct 3D extracellular matrix model systems: collagen, fibrin, and Matrigel. We decipher this remarkable behavior by introducing Nonlinear Stress Inference Microscopy (NSIM), a novel technique to infer stress fields in a 3D matrix from nonlinear microrheology measurement with optical tweezers. Using NSIM and simulations, we reveal a long-ranged propagation of cell-generated stresses resulting from local filament buckling. This slow decay of stress gives rise to the large spatial extent of the observed cell-induced matrix stiffness gradient, which could form a mechanism for mechanical communication between cells

Lightweight conductive graphene/thermoplastic polyurethane foams with ultrahigh compressibility for piezoresistive sensing

Lightweight conductive porous graphene/thermoplastic polyurethane (TPU) foams with ultrahigh compressibility were successfully fabricated by using the thermal induced phase separation (TISP) technique. The density and porosity of the foams were calculated to be about 0.11 g cm−3 and 90% owing to the porous structure. Compared with pure TPU foams, the addition of graphene could effectively increase the thickness of the cell wall and hinder the formation of small holes, leading to a robust porous structure with excellent compression property. Meanwhile, the cell walls with small holes and a dendritic structure were observed due to the flexibility of graphene, endowing the foam with special positive piezoresistive behaviors and peculiar response patterns with a deflection point during the cyclic compression. This could effectively enhance the identifiability of external compression strain when used as piezoresistive sensors. In addition, larger compression sensitivity was achieved at a higher compression rate. Due to high porosity and good elasticity of TPU, the conductive foams demonstrated good compressibility and stable piezoresistive sensing signals at a strain of up to 90%. During the cyclic piezoresistive sensing test under different compression strains, the conductive foam exhibited good recoverability and reproducibility after the stabilization of cyclic loading. All these suggest that the fabricated conductive foam possesses great potential to be used as lightweight, flexible, highly sensitive, and stable piezoresistive sensors

Comparative extraction of melon seed (Cucumis melo L.) oil by conventional and enzymatic methods: physicochemical properties and oxidative stability

Oil was extracted from melon seeds with three different methods (Soxhlet, cold-pressed, aqueous enzymatic extraction), aiming to evaluate its physicochemical properties and oxidative stability. The melon seed oil contained high levels of linoleic acid (53.6 %–70.8 %, w/w), squalene (101.1–164.7 mg/100 g), and β-sitosterol (119.5–291.9 mg/100 g). Results showed that the choice of the extraction method did not alter the fatty acid composition, but impacted on the physicochemical properties, the content of bioactive compounds and oxidative stability of the oil. Specifically, melon seed oil obtained by aqueous enzymatic extraction (AEE) exhibited higher tocopherol content and better oxidative stability compared to the oil obtained by other two extraction methods. Overall, AEE is a promising oil extraction method and could be an alternative to conventional oil extraction methods that could be implemented for the production of high-quality melon seed oil

Ionic liquid-mediated regeneration of cellulose dramatically improves decrystallization, TEMPO-mediated oxidation and alkyl/alkenyl succinylation

This work demonstrated a successful strategy that simple ionic liquids (ILs) mediated pretreatment could effectively reduce crystallinity of cellulose from 71 % to 46 % (by C2MIM.Cl) and 53 % (by C4MIM.Cl). The IL-mediated regeneration of cellulose greatly promoted its reactivity for TEMPO-catalyzed oxidation, which the resulting COO− density (mmol/g) increased from 2.00 for non-IL-treated cellulose to 3.23 (by C2MIM.Cl) and 3.42 (C4MIM.Cl); and degree of oxidation enhanced from 35 % to 59 % and 62 %, respectively. More significantly, the yield of oxidized cellulose increased from 4 % to 45–46 %, by 11-fold. IL-regenerated cellulose can also be directly subjected to alkyl/alkenyl succinylation without TEMPO-mediated oxidation, producing nanoparticles with properties similar to oxidized celluloses (55-74 nm in size, −70–79 mV zeta-potential and 0.23–0.26 PDI); but in a much higher overall yield (87–95 %) than IL-regeneration-coupling-TEMPO-oxidation (34–45 %). Alkyl/alkenyl succinylated TEMPO-oxidized cellulose showed 2–2.5 times higher ABTS* scavenging ability than non-oxidized cellulose; however, alkyl/alkenyl succinylation also resulted in a significant decline in Fe2+ chelating property