55 research outputs found

    Generation and Role of Oscillatory Contractions in Mouse Airway Smooth Muscle

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    Background/Aims: Tetraethylammonium chloride (TEA) induces oscillatory contractions in mouse airway smooth muscle (ASM); however, the generation and maintenance of oscillatory contractions and their role in ASM are unclear. Methods: In this study, oscillations of ASM contraction and intracellular Ca2+ were measured using force measuring and Ca2+ imaging technique, respectively. TEA, nifedipine, niflumic acid, acetylcholine chloride, lithium chloride, KB-R7943, ouabain, 2-Aminoethoxydiphenyl borate, thapsigargin, tetrodotoxin, and ryanodine were used to assess the mechanism of oscillatory contractions. Results: TEA induced depolarization, resulting in activation of L-type voltage-dependent Ca2+ channels (LVDCCs) and voltage-dependent Na+ (VNa) channels. The former mediated Ca2+ influx to trigger a contraction and the latter mediated Na+ entry to enhance the contraction via activating LVDCCs. Meanwhile, increased Ca2+-activated Cl- channels, inducing depolarization that resulted in contraction through LVDCCs. In addition, the contraction was enhanced by intracellular Ca2+ release from Ca2+ stores mediated by inositol (1,4,5)-trisphosphate receptors (IP3Rs). These pathways together produce the contractile phase of the oscillatory contractions. Furthermore, the increased Ca2+ activated the Na+-Ca2+ exchanger (NCX), which transferred Ca2+ out of and Na+ into the cells. The former induced relaxation and the latter activated Na+/K+-ATPase that induced hypopolarization to inactivate LVDCCs causing further relaxation. This can also explain the relaxant phase of the oscillatory contractions. Moreover, the depolarization induced by VNa channels and NCX might be greater than the hypopolarization caused by Na+/K+-ATPase alone, inducing LVDCC activation and resulting in further contraction. Conclusions: These data indicate that the TEA-induced oscillatory contractions were cooperatively produced by LVDCCs, VNa channels, Ca2+-activated Cl- channels, NCX, Na+/K+ ATPase, IP3Rs-mediated Ca2+ release, and extracellular Ca2+

    Semen cassiae Extract Inhibits Contraction of Airway Smooth Muscle

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    β2-adrenoceptor agonists are commonly used as bronchodilators to treat obstructive lung diseases such as asthma and chronic obstructive pulmonary disease (COPD), however, they induce severe side effects. Therefore, developing new bronchodilators is essential. Herbal plants were extracted and the extracts’ effect on airway smooth muscle (ASM) precontraction was assessed. The ethyl alcohol extract of semen cassiae (EESC) was extracted from Semen cassia. The effects of EESC on the ACh- and 80 mM K+-induced sustained precontraction in mouse and human ASM were evaluated. Ca2+ permeant ion channel currents and intracellular Ca2+ concentration were measured. HPLC analysis was employed to determine which compound was responsible for the EESC-induced relaxation. The EESC reversibly inhibited the ACh- and 80 mM K+-induced precontraction. The sustained precontraction depends on Ca2+ influx, and it was mediated by voltage-dependent L-type Ca2+ channels (LVDCCs), store-operated channels (SOCs), TRPC3/STIM/Orai channels. These channels were inhibited by aurantio-obtusin, one component of EESC. When aurantio-obtusin removed, EESC’s action disappeared. In addition, aurantio-obtusin inhibited the precontraction of mouse and human ASM and intracellular Ca2+ increases. These results indicate that Semen cassia-contained aurantio-obtusin inhibits sustained precontraction of ASM via inhibiting Ca2+-permeant ion channels, thereby, which could be used to develop new bronchodilators

    Efficient recovery of phosphate from simulated urine by Mg/Fe bimetallic oxide modified biochar as a potential resource

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    International audienceThe massive use of phosphate fertilizers in agriculture is costly and induces water pollution, calling for more sustainable phosphate sources in the context of the circular economy. Here we prepared a new adsorbent based on waste straw biochar modified with the Mg/Fe bimetallic oxide, namely the Mg/Fe biochar, to recover phosphate from the simulated urine as an possible phosphate fertilizer. About 90% phosphate was recovered from the simulated urine with a wide pH range of 3.0–9.0 and a maximum adsorption capacity of 206.2 mg/g, using 1 g/L of Mg/Fe modified biochar. A pseudo second-order kinetics and Sips model were proposed to fit the experimental data well, suggesting that the adsorption was controlled by physical and chemical processes, which is driven by electrostatic attraction, intra-particle diffusion, ion exchange and surface ligand exchange. Overall, theMg/Fe biochar is renewable and can recover more than 70% of phosphate in the simulated urine after 5 cycles of reuse, which appears as a safe and efficient adsorbent to recycle phosphate from urine

    Mechanical properties of multilayer combined gradient cellular structure and its application in the WLL

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    In order to improve the buffering performance of a walkable lunar lander (WLL), an optimization method of multi-layer combined gradient cellular structure (MCGCS) is proposed. The impact load, impact action time, impact overload, and deformation amount are analyzed. The buffering performance of the material is evaluated and verified effectively with the simulation data. The overload acceleration of the WLL, the volume, and mass of the buffer material were set as the space-time solution to the optimal buffer problem, and the complex relationship between the material structure parameters and the buffer energy absorption (EA) parameters was established based on the sensitivity analysis method, and the buffer structure parameters were automatically optimized. The buffer energy absorption characteristics of the MCGCS are like the simulation results, and it has a good buffering effect, which provides a new research perspective for the excellent landing buffering mechanical properties of the WLL and a new idea for the application of engineering materials

    Electrochemical crystallization for recovery of phosphorus and potassium from urine as K-struvite with a sacrificial magnesium anode

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    International audienceDeclining earth resources, rising ore cost and increasing pollution are calling for recycling of wastewater in the context of the circular economy. In particular, urine is a potential source of phosphorus (P) and potassium (K), yet currently available methods for P and K recovery are limited in efficiency. Here, we designed an electrochemical crystallization system using sacrificial magnesium anodes to recover P and K in the form of K-struvite (MgKPO 4 •6H 2 O) from simulated urine at low (P/K = 0.25) and high (P/K = 0.6) phosphate levels, respectively. Results show optimal recoveries of 88.5% for P and 35.4% for K in the form of rod-shaped K-struvite at 3.5 mA/cm 2 , though higher current density reduced recovery due to side reactions and pH increase. Seeding prefabricated struvite crystals at 1.6 g/L into urine enhanced the recovery of K by 14.7% and of P by 23.7% compared to the control group. Overall, our findings show that electrochemical crystallization is promising to recover K-struvite fertilizers

    Efficient recovery of phosphate from urine using magnesite modified corn straw biochar and its potential application as fertilizer

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    International audienceConventional phosphate fertilization is costly, carbon intensive, induces water pollution, and depletes natural phosphate ores, calling for alternative circular sources such as recycling phosphate from urine. However, actual phosphate adsorbents are moderately efficient and generate additional waste. Magnesite-modified biochar was synthesized by co-pyrolysis of corn straw and magnesite, which was used to adsorb phosphate in simulated urine. We compared the properties with other magnesium-based biochar materials and conducted pot experiments to assess feasibility of the saturated magnesite-modified biochar using as an alternative phosphate fertilizer. The results showed that the maximum adsorption capacity of magnesite-modified biochar for phosphate in urine was 176.16 mg/g, with the primary adsorption mechanisms involving electrostatic attraction and ligand exchange. Pot experiments showed that after 21 days, the germination rate and plant height of plants were 5.0-5.8 and 9.4-10.0 times respectively higher than those of plants in soil without biochar application. Overall, the prepared magnesite-modified biochar promises as an adsorbent with dual benefits in water treatment and phosphorus recovery. The saturated magnesite-modified biochar is proved as a good alternative phosphate fertilizer with carbon fixation, emission reduction and phosphorus cycling functions

    Paleofluid restoration and its application in studies of reservoir forming: A case study of the Ordovician in Tarim Basin, NW China

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    Karst reservoir paleofluid types of the Ordovician formation in the Tarim Basin are restored based on the analysis of element boron of filled mud, the test of fluid inclusions homogenization temperature and salinity, liquid anion and hydroxyl isotope of filled calcite in vug-fractures, and regional geologic background. The origin of the karst reservoirs are analyzed on this basis. The element boron contents of mud filled in vug-fractures are less than 80 μg/g generally; fluid inclusions have different homogenization temperatures in different regions, and the salinities are in a large range. The HCO3− contents are high, and the Cl− and SO42− contents are dispersive in the liquid component of the fluid inclusions. The hydroxyl isotope contents are relatively dispersive, with relatively negative δD value and positive δ18O value. This evidence shows that the paleofluid of the Ordovician was from supergene atmospheric freshwater, buried fresh-brackish mixed water, seawater or concentrated seawater, and buried brine from underlying dolomite or evaporate rock of the Cambrian formation. The main constructive diagenesis for the formation of vug-cave type reservoirs is erosion and dissolution caused by atmospheric freshwater, and the reservoirs have been subjected to thermal fluid reformation from underlying evaporate rock of the Cambrian during burial stage. Key words: Tarim Basin, karst reservoir, paleofluid restoration, reservoir forming mechanism, element boron, fluid inclusions homogenization temperature, fluid inclusions salinity, hydrogen and oxygen isotopic compositio
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