Kinetic Study of Subcritical Water Extraction of Scopoletin, Alizarin, and Rutin from Morinda citrifolia

Noni fruits (Morinda citrifolia) are a source of phenolic bioactive compounds (scopoletin, alizarin, and rutin), which have antioxidant, antimicrobial, anticancer, and anti-inflammatory activities. In this study, subcritical water was applied to determine the extraction yields and kinetics of phenolic compounds from noni fruits. The scopoletin and alizarin yields increased with the increase in temperature from 100 to 140 °C, while that of rutin increased up to 120 °C and then decreased at 140 °C. The yields of all the compounds rapidly increased from 1 to 2 mL/min and then slightly up to 3 mL/min of water flow rate. The extraction kinetics were assessed using two mathematical models. The two-site kinetic desorption model had a better fit for all experimental conditions throughout the extraction cycle and best described the extraction kinetics of phenolic compounds from noni fruits. The diffusion coefficients of scopoletin and alizarin at 140 °C and 3 mL/min were 3.7- and 16.2-fold higher than those at 100 °C and 1 mL/min, respectively. The activation energies of alizarin were 2.9- to 8.5-fold higher than those of scopoletin at various flow rates. Thus, subcritical water could be an excellent solvent with higher extraction yields and shorter extraction times using an environmentally friendly solvent.

Study on Desorption Experiment and Desorption Model of Deep Shale Gas Containing Water

In this work, the methane desorption isothermal curves at different water contents on deep sampled from Western Chongqing of China were measured at pressures up to 65 MPa and at 130°C by the volumetric method. In the first instance, the desorption increases with the decrease of pressure, the adsorbed gas desorbs slightly with decreasing pressures from 65 to 30 MPa. When the pressure drops to 30–20 MPa, the desorption rate increases rapidly with the decrease of pressure and the desorption curve begins to separate from the adsorption curve, resulting in desorption hysteresis. At last, when the pressure is lower than 20 MPa, the desorption increases almost linearly with the further decrease of pressure, but eventually there will be some adsorbed gas which cannot be desorbed to form residual adsorbed gas. After that, the isotherm desorption data of CH4 was fitted using the improved desorption model. The fitting results showed that the improved desorption model can be used to describe the desorption process of deep shale gas containing water and has a strong applicability. In addition, the critical desorption pressure increases with increasing water content. When the water content is lower than 1%, the effect of the water content on the desorption of deep shale gas increases rapidly with increasing water content, as well as when the water content is greater than 1%, the impact changes slowly.

Transient Nanoscale Tribofilm Growth: Analytical Prediction and Measurement

A new method for the simultaneous in situ measurement and characterisation of molybdenum-based tribofilms is presented, based on lateral force microscopy. The simultaneity of measurements is crucial for a fundamental understanding of the tribochemical phenomena. A new analytical method is also presented, which combines a BET multi-layer adsorption/desorption model for boundary-active lubricant species-surface combination with the modified shear-promoted thermal activation Arrhenius equation. Therefore, the expounded method integrates the mechanical, physical and chemical aspects of the adsorption-bonding process as a detailed multi-step phenomenon. The method provides detailed explanations of the measured tribofilm growth, in a fundamental manner, not hitherto reported in the literature. Therefore, the combined experimental methodology and modelling approach provides a significant advance in the understanding of tribofilm formation. Furthermore, the developed model has the potential to explain the behaviour of many complex lubricant formulations and the resulting multi-species tribofilms, generated through synergistic and/or antagonistic constituent adsorption and shear-promoted activation.

Numerical Simulation Research on Well Pattern Optimization in High–Dip Angle Coal Seams: A Case of Baiyanghe Block

The Baiyanghe block in Fukang, Xinjiang, China, is rich in coalbed methane (CBM) resources, and several pilot experimental wells have yielded high production. Due to the high dip angle (35–55°) of the coal seam in this area, the lack of understanding of the geological characteristics, the physical properties of coal, and gas–water migration law lead to immature development techniques and poor overall development benefits. We first conducted desorption and adsorption tests on low-rank coal of this area and found residual gas in the coal. We established a coalbed methane desorption model suitable for this area by modifying the isotherm adsorption model. Next, by analyzing the influence of the gas–water gravity differentiation in the high–dip angle coal seam and the shallow fired coalbed methane characteristics in this area, we discovered the leakage of CBM from the shallow exposed area of the coal seam. Given the particular physical property of coal and gas–water migration characteristics in this area, we optimized the well pattern: (i) the U-shaped along-dip horizontal well group in coal seams is the main production well for gas production with a spacing distance of 312 m; (ii) a multistage fracturing well drilled in the floor of coal is for water production; and (iii) vertical wells with a spacing distance of 156 m in the shallow area is to capture CBM leakage. Using numerical simulation and net present value (NPV) economics models, we optimized the well pattern details. Applying our CBM desorption model, the numerical simulator can improve the accuracy of the low-rank coalbed methane productivity forecast. The optimization results demonstrated the following: 1) the cumulative gas production of single U-shaped well increased by 89% with the optimal well spacing, 2) the cumulative gas production of the well group increased by 87.54% after adding the floor staged horizontal well, and 3) the amount of CBM leakage decrease by 67.59%.

An equilibrium desorption model for the strength and extraction yield of full immersion brewed coffee

The sensory qualities of brewed coffee are known to be strongly correlated with the total dissolved solids (TDS) and extraction yield (E) of the brew. Here, we derive a predictive model for the TDS and E of full immersion brewed coffee using a pseudo-equilibrium desorption approach. Assuming a single, species-averaged equilibrium constant $$K$$ K yields theoretical predictions indicating that the TDS is approximately inversely proportional to the water/coffee mass brew ratio, while E is independent of the brew ratio. Our experimental results strongly accord with both theoretical predictions, and indicate that E is approximately 21% over a wide range of brew ratios. An analysis of the standard oven-drying method for measuring E indicates that it yields significant underestimates of the true value at equilibrium, due to retained brew within the spent moist grounds. We further demonstrate that $$K$$ K is insensitive to grind size, roast level, and brew temperature over the range 80–99 °C. Taken together, our results indicate that full immersion brewing offers precise control over the TDS at equilibrium but little control over E, and that practitioners should pay careful attention to their brew ratio as the most important parameter for full-immersion brewing.

An Equilibrium Desorption Model for the Strength and Extraction Yield of Full Immersion Brewed Coffee

The sensory qualities of brewed coffee are strongly correlated with the total dissolved solids (TDS) and extraction yield (E) of the brew. Here, we derive a predictive model for the TDS and E of full immersion brewed coffee using a pseudo-equilibrium desorption approach. Assuming a single, species-averaged equilibrium constant K yields theoretical predictions indicating that the TDS is approximately inversely proportional to the water/coffee mass brew ratio, while E is independent of the brew ratio. Our experimental results strongly accord with both theoretical predictions, and indicate that E is approximately 21% over a wide range of brew ratios. An analysis of the standard oven-drying method for measuring E indicates that it yields significant underestimates of the true value at equilibrium, due to retained brew within the spent moist grounds. We further demonstrate that K is insensitive to grind size, roast level, and brew temperature over the range 80-99°C. Taken together, our results indicate that full immersion brewing offers precise control over the TDS at equilibrium but little control over E, and that practitioners should pay careful attention to their brew ratio as the most important parameter for full-immersion brewing.