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Summary Severe formation damage often occurs during the drilling process, which significantly impedes the timely discovery, accurate evaluation, and efficient development of deep tight clastic gas reservoirs. The addition of formation protection additives into drilling fluid after diagnosing the damage mechanism is the most popular technique for formation damage control (FDC). However, the implementation of traditional FDC measures does not consider the multiscale damage characteristics of the reservoir. The present study aims at filling this gap by providing a complete and systematic damage control methodology based on multiscale FDC theory. First, the characteristics of multiscale seepage channels were described through petrology, petrophysics, and well-history data. Subsequently, based on laboratory formation damage evaluation experiments, the formation damage mechanism of each seepage scale was determined. Finally, based on the multiscale formation damage mechanism, a systematic multiscale FDC technology was proposed. Through the use of optimized drilling fluid based on multiscale FDC theory, high-permeability recovery ratio (PRR), high-pressure bearing capacity of plugging zone, and low cumulative filtration loss were observed by laboratory validation experiments. Shorter drilling cycle, less drill-in-fluid loss, lower skin factor, and higher production rates were obtained by using the optimized FDC drilling fluid in field application. This multiscale FDC theory shows excellent results in minimizing formation damage, maintaining original production capacity, and effectively developing gas reservoirs with multiscale pore structure characteristics.

In shale gas reservoirs, the fluid flowback rates have become one of the key parameters to evaluate the fracturing operation and manage fracturing fluid after well stimulation. Based on experimental tests and a field data analysis, this paper proposed a method to estimate the fracturing fluid recovery. First, fracturing fluid imbibition and flowback experiments were conducted with fractured and matrix downhole shale plugs, and the average flowback rates for matrix and fractured samples were tested. Then, using a material balance model, the percentages of fluid retained in matrix and fractures are determined with the early-stage well production data. Combining the experimental and field results, a linear superposed model was adopted to compute the final fracturing fluid recovery. The values for the selected two wells were 23.3% and 26.2%, respectively, slightly smaller than the field-recorded values, which may be attributed to the underestimation of the flowback rate in fracture networks. A sensitivity analysis demonstrated that the recovery was more sensitive to the fluid flowback rate in fractures as more than a half of the fracturing fluid stayed there. The outcomes of this paper may explain the reasons why the fracturing fluid recovery of shale gas wells fluctuates in a wide range and wells with low flowback rates usually have a high productivity.

A rhodium-catalyzed tandem enantioselective C-H silylation/alkene hydrosilylation of dihydrosilanes, which enables the streamlined construction of a wide range of silicon-stereogenic silanes, is successfully developed. This process involves a SiH2-steered highly enantioselective C-H silylation to furnish the corresponding desymmetric monohydrosilanes, which are subsequently trapped with alkenes in a stereospecific fashion to build functionally diverse asymmetrically tetrasubstituted silanes. This general strategy combines readily available dihydrosilanes and alkenes to construct various enantioenriched silicon-stereogenic silanes, including 9-silafluorenes, Si-bridged ladder compounds, and benzosilolometallocenes, in a single step with good to excellent yields and enantioselectivities.

Focused on the lost circulation control in deep naturally fractured reservoirs, the multiscale structure of fracture plugging zone is proposed based on the theory of granular matter mechanics, and the structural failure pattern of plugging zone is developed to reveal the plugging zone failure mechanisms in deep, high temperature, high pressure, and high in-situ stress environment. Based on the fracture plugging zone strength model, key performance parameters are determined for the optimal selection of loss control material (LCM). Laboratory fracture plugging experiments with new LCM are carried out to evaluate the effect of the key performance parameters of LCM on fracture plugging quality. LCM selection strategy for fractured reservoirs is developed. The results show that the force chain formed by LCMs determines the pressure stabilization of macro-scale fracture plugging zone. Friction failure and shear failure are the two major failure patterns of fracture plugging zone. The strength of force chain depends on the performance of micro-scale LCM, and the LCM key performance parameters include particle size distribution, fiber aspect ratio, friction coefficient, compressive strength, soluble ability and high temperature resistance. Results of lab experiments and field test show that lost circulation control quality can be effectively improved with the optimal material selection based on the extracted key performance parameters of LCMs. Key words: deep layer, fractured reservoir, lost circulation, fracture plugging zone, multi-scale structure, strength and stability, loss control material

Magnetic polyphosphazene (MPZS) particles coated by Ag nanoparticles (MPZS-Ag) have been developed as surface enhanced Raman spectroscopy (SERS) substrates for sensitive detection of melamine in aqueous solutions and milk samples. 5,5′-Dithiobis-(2-nitrobenzoic acid) (DTNB) was used as model analyte to test the SERS activity of the MPZS-Ag particles. The prepared MPZS-Ag particles possess both magnetic responsiveness and excellent SERS properties. SERS detection of different concentrations of melamine aqueous solutions and spiked milk samples were performed by the MPZS-Ag particles. The limit of detection (LOD) of the melamine in aqueous solutions was 10−7 mol/L (0.0126 mg/L) and 0.6 mg/L in real milk samples using the MPZS-Ag particles as SERS substrates. The LOD of the melamine are much lower than the safety values of Food and Drug Administration and Codex Alimentarius Commission. These results indicate that the MPZS-Ag particles have promising application prospect for SERS analysis in food safety fields.

Natural antioxidants possess health beneficial properties and are being substantially used in foods, cosmetics and pharmaceutical products. Polyphenolics content, antioxidant activity and HepG2 liver cancer cells’ inhibition potential were determined and compared in the fruit of apricot cultivars collected from lower Himalayan region of Pakistan using standard analytical procedures. Comparatively, fruit of AP3 cultivar had highest levels of total phenolics and total flavonoids contents (220.5 ± 15.9 mgGAE/100 g and 382.0 ± 18.0 mgQE/100 g, respectively) on fresh weight basis. Fruit of the same cultivar had maximum DPPH scvenging potential (94.24 ± 4.55%), oxygen radicals absorbance capacity at 4.71 ± 0.12 mMolTE/100 g and inhibition of HepG2 cancer cells (45.80 ± 4.01 µMolQE/100 g). Though, fruit of AP4 cultivar was rich in vanillic acid, caffeic acid, vanillin, epi-catechin and quercetin, but had relatively low antioxidant and anticancer potential. Disparities in the phytochemical composition and properties of apricot fruit are attributed to genetic differences and growing conditions. Total phenolics, total flavonoids and caffic acid depicted highly significant positive association (˃90%) with ORAC, CAA and FRAP. Our findings suggest that being a rich source of health beneficial secondary metabolites, apricot fruit of Himalayan region of Pakistan could contribute considerably in socio-economic development of the local communities and as a functional food in regional and global markets.

Summary Conventional drill-in fluid commonly induces formation damage during the drill-in process in deep-fractured tight reservoirs, which results in severe well-production decline. It is mainly attributed to the inadequate understanding of multiscale damage mechanisms, unique engineering, and geological conditions of these reservoirs. To fill this gap, an engineered formation-damage-control (FDC) drill-in-fluid technology is developed for a representative deep-fractured reservoir in China. Petrology, petrophysics, and well-history data are summarized to analyze the reservoir engineering and geological properties and the potential formation-damage factors. Drill-in-fluid-induced damage is experimentally evaluated on both matrix and fracture core samples at 130°C. Additionally, drill-in-fluid invasion depth is quantitatively evaluated using a mathematical model. The multiscale mechanisms of drill-in-fluid-induced formation damage are revealed to design the FDC drill-in-fluid technology. The optimized drill-in fluid is engineered by a specific assembly of acid-soluble-fiber bridging particles, filling particles, and an oil-soluble temporary-plugging agent. The effectiveness of the engineered FDC drill-in fluid is validated by laboratory experiment comprising basic-parameter tests and evaluation of FDC performance. Successful field application of the engineered FDC drill-in fluid in Tarim Basin is also discussed.

As the first external liquids that are introduced into a reservoir rock, suitable drill-in fluids not only prevent phase trapping-induced permeability reduction (also referred to as phase trapping damage) caused by the drill-in fluid itself but also minimize any phase trapping damage caused by the invasion of subsequent working fluids. An ultra-deep tight sandstone reservoir in the Tarim Basin, NW China is considered as a case study, and this paper presents the results of an extensive series of phase trapping damage investigations that were carried out to determine the permeability reduction in the reservoir rock that comes into contact with different working fluids during the processes of drilling, drill stem tests, completion and well tests. Both the pore microstructure and surface properties were also investigated. The experimental results showed that the integrated phase trapping damage ratio (PDR) of water-based drill-in fluids (WBDF)-organic salt completion fluids (PDR = 0.99) was greater than that of oil-based drill-in fluids (OBDF)-organic salt completion fluids (PDR = 0.88). The analysis suggests that the OBDF is more effectively in inhibiting the absorption of the filtrate of the completion fluids compared with WBDF. A procedure for reducing phase trapping damage by OBDF is presented, and a numerical simulation model is developed to validate the procedure. The results could be useful in understanding and selecting the best drill-in fluids and completion fluids to minimize phase trapping damage in ultra-deep tight gas reservoirs.

Wellbore failure/collapse is a common problem encountered during coalbed methane (CBM) production. The wellbore failures lead to significant production of coal fines, reductions in well productivity, and downhole accidents. These negative outcomes make it essential to predict the conditions responsible for the failure of wellbores and to know when control measures are needed. This study proposed a semi-analytical model of coal wellbore stability during primary CBM recovery. The model incorporates the effects of sorption-induced strain, horizontal stress anisotropy, reservoir depletion, and well trajectory. Plane-strain poroelasticity and the Mogi–Coulomb failure criterion were applied to estimate critical drawdown and depletion for coal wellbore failure. A real field case from the San Juan Basin was simulated to validate the applicability of the proposed model. Wellbore failure-free operating envelopes were then generated for the life span of the field. The effects of sorption-induced strain and well trajectory on wellbore stability were analyzed, and the onset conditions for local wellbore failure and reservoir-scale coal failure were compared. Results revealed that the critical reservoir pressure (CRP_1) for local wellbore failure exceeded the pressure (CRP_2) for field-scale failure, i.e., local wellbore failure occurred earlier than reservoir failure. The CRP_1 value predicted using the model aligned well with actual field observations, thus verifying the model. The desorption-induced shrinkage effect inhibited wellbore failure when radial stress was the minimum principal stress; however, the shrinkage effect enhanced wellbore failure when radial stress was the intermediate principal stress. The optimal well trajectory for the San Juan Basin occurred at the inclination angle of approximately 20° and azimuth of 90°; and the CRP_1 had its minimum value at this trajectory. This study can help optimize field production plans, well trajectories, and well completion to mitigate coal wellbore instability.

It is difficult to stimulate coal reservoirs in physical approaches, and the recovery factor of coalbed methane (CBM) can be enhanced by applying strong oxidizers through oxidation to stimulate coal reservoirs. At present, however, there have been very few studies on the oxidation of CBM and fewer experimental studies for systematically evaluating the effect of oxidation on the seepage capacity of coal reservoirs. In this paper, the coal samples taken from coal seams of the Jurassic Xishanyao Formation in the Heishan Coal Mine, Toksun, Xinjiang, were selected as the study objects. Hydrogen peroxide solution immersion experiments were carried out on columnar and powdered coal samples, respectively to measure the permeability of columnar coal samples, the dissolution rate of powdered coal samples and the property parameters of hydrogen peroxide solution. Then, the reaction mechanisms between coal samples and hydrogen peroxide and the mechanisms to improve the seepage capacity of coal reservoirs were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM), infrared spectrum and wetting angle measurement. Finally, the stimulation effect of oxidation was compared with that of acidification. The following research results were obtained. (1) The permeability of coal samples is increased significantly after oxidation to 1.4–3.2 times the original permeability. (2) A large number of micro-fractures and dissolved pores are formed in the coal samples after oxidation, and consequently pore connectivity is improved greatly. Thus, the amount of associative hydroxyl and carboxyl functional groups on the surface of the coal samples increases, and the water wettability on the surface reduces. (3) Organic matters and pyrites are oxidized and consumed easily, and the generated H+ and micro-molecular aliphatic acids further dissolve inorganic mineral components. (4) Oxidation also has the advantage of acidification for dissolving inorganic mineral components, so there is a low and controllable probability of generating coal powder. In conclusion, applying strong oxidizers has the potential to become a new technology for coal reservoir stimulation. Keywords: Coal rock, Oxidation, Permeability, Pore connectivity, Acidification, Micro-fracture and dissolved pore, Dissolving inorganic minerals, Coal reservoir stimulation

Methane diffusion plays an essential role in shale gas production, linking gas desorption and seepage. Accurate measurement of the methane diffusion coefficient is a key factor for evaluating the potential for multi-gas transport behavior in shales. Thus, a pressure pulse experiment was carried out in this work, the multiscale mass transfer process of methane was simulated, and the mechanism of pore pressure effect on the diffusion ability of shale gas was revealed. The experimental results indicate that the diffusion of methane can be divided into three stages based on the relationship between pressure and time, in which different pore diameters correspond to different diffusion mechanisms. In Stage I, free molecule diffusion is dominant; in Stage II, diffusion occurs through relatively large pores as a result of the combined action of Knudsen diffusion and surface diffusion in those pores; in Stage III, it is attributed to internal configurational diffusion in organic-matter pores. A higher pore pressure increases methane adsorption capacity, and multilayers adsorption of methane on the pore surface reduces the pore sizes. The Knudsen diffusion rate then decreases and the configurational diffusion rate increases. Therefore, as pore pressure increases, the diffusion coefficient of large particles in Stage II decreases, while that in Stage III increases. It is shown that the multiscale mass transfer of shale gas with pore pressure can be effectively simulated through the pressure pulse method proposed in this paper. The method additionally allows the shale formation temperature and overburden pressure to be reliably simulated. This work provides an important workflow for the investigation of gas multiscale transport behavior in shales.

Wound dressing, primarily used to protect skin lesions, has recently evolved into advanced biomaterial-based membranes that support or induce skin regeneration. Here, we fabricated a chitosan/aloe film that provides a sustaining release of curcumin for promoting wound healing and skin regeneration. Uniform embedding of curcumin-encapsulated poly(lactic-co-glycolic acid) microspheres in the chitosan/aloe membrane were achieved with a high-power ultrasonic emulsification and a tape-casting process. The micro-structural, physicochemical and mechanical properties of the composite film were examined by SEM, XRD, ATR-FTIR and tensile tests. The biocompatibility of the composite film was tested with NIH-3T3 cells culture in vitro. Then the composite film is implanted in a full-thickness skin wound model in Wistar rats. The implantation of curcumin-releasing film led to the accelerated would healing and promoted skin tissue regeneration as compared to the untreated control and the film without curcumin. In addition, sustain-released curcumin likely shows effect on restraining inflammation and cicatrices. Our findings demonstrate that the chitosan/aloe film with controlled delivery of curcumin promotes the intrinsic regeneration of skin tissues.

A new folic acid (FA)-conjugated poly (lactic-co-glycolicacid) (PLGA)-polyethylene glycol (PEG) nano-noisome was prepared. The noisome was employed as a drug delivery system to load curcumin (Cur) as a model drug and fluorescent probe for cervical cancer therapy and cell imaging. The Fe3O4@PLGA-PEG@FA noisomes were prepared through facile emulsion solvent evaporation and conjugation chemistry method, possessing the properties of high rapid magnetic separation and targeting character. X-ray photoelectron spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) were adopted to characterize the chemical structure and properties of these niosomes. MTT assay revealed that the blank noisomes exhibited excellent biocompatibility. The in vitro drug loading and release behavior studier showed the as prepared nano-noisome presented ultrahigh performance as drug carrier. The confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) experiments demonstrated that Cur-loaded Fe3O4@PLGA-PEG@FA niosomes achieved significantly high targeting efficiency for cervical cancer. Additionally, the FA-targeted niosomes exhibited higher antitumor efficiency than free Cur. Cell morphology, the mitochondrial membrane potential and cell cycle changes indicated that Cur-loaded niosomes induced HeLa229 cells to apoptosis by destroying mitochondrion of cervical tumor cells, simultaneously changing nuclear morphology and blocking tumor cell proliferation. These results demonstrate that Fe3O4@PLGA-PEG@FA noisomes have promising applications as targeted drug delivery system for sustained drug release in cancer treatment.

The purpose of the present study is to evaluate the preparation and the structure of fraction OP-Ia and its protective effect against UV-induced photoaging through the MAPKs signaling pathway. Fractions OP-Ia and OP-Ib were prepared by enzymatic hydrolysis and purified by ultrafiltration (5 kDa) and gel chromatography (Sephadex G-25). The reducing power and superoxide radical scavenging ability were evaluated, which showed that OP-Ia had stronger antioxidant activity than OP-Ib. Next, ten peptides were identified in OP-Ia by UPLC-MS/MS. The mechanism of the anti-photoaging activity for fraction OP-Ia was investigated through the MAPKs pathway based on the HaCaT cell line. Fraction OP-Ia could inhibit the generation of ROS and the decline of cell viability induced by UV radiation, meanwhile downregulate the expression of IL-1β, IL-8, c-Jun, c-Fos, p65 NF-κB and p38 MAPK genes. Overall, the results showed that the fraction OP-Ia could be a potent component of functional foods with UV protection property.

Salt precipitation and its induced problems are increasingly prominent with the development of deep and ultra-deep tight sandstone gas reservoirs with high salinity formation water. In this paper, the change of porosity and permeability of a series of tight sandstone was measured, and then the morphology and occurrence state of crystalloid salt within the pore was observed by SEM. Meanwhile, high-pressure mercury injection analyzed the changes of pore size distribution. Experimental results show that salt precipitation could affect the porosity and permeability, which decreases by 53% and 65% after salt precipitation, respectively. The occurrence state of the crystalloid salt can be divided into three models: superposition growth along with the intergranular pore-fractures/natural micro-fractures, lamellar growth attached to the surface of the hydrophilic mineral like I/S interstratified mineral and the individual particles located in the corner of the pore. When the size of crystalloid salt is closer to the pore size distribution of tight sandstone, it will cause cracks and pore throat blockage easily. It is suggested that salt wash pretreatment should be carried out before analysis of tight sandstone with porosity less than 5%. Keywords: Salt precipitation, Tight sandstone, Porosity, Permeability, Formation damage

Different injection and production pressure modes for underground gas storage have great differences on the permeability of formation rocks. In this paper, core flow experiments are designed and carried out to simulate the real pressure gradient of the injection and production in underground gas storage, and these experiments are carried out under in-situ stress conditions. The permeability and turbidity of core outlet were monitored during the experiment. The experimental results show that under different injection-production pressure modes, the permeability changes and the turbidity at the core outlet changes. It was observed by scanning electron microscope that there were fines on the fracture wall after the experiment. Analysis shows that fine migration is the main reason for the change of permeability under different injection-production pressure modes.

An asymmetric synthesis of silicon-stereogenic monohydrosilanes by rhodium-catalyzed dehydrogenative C-H silylation is developed. The process is suitable for the synthesis of various asymmetrically trisubstituted 1

A rhodium(I)-catalyzed enantioselective silylation of aliphatic C-H bonds for the synthesis of silicon-stereogenic dihydrobenzosiloles is demonstrated. This reaction involves a highly enantioselective intramolecular C(sp3 )-H silylation of dihydrosilanes, followed by a stereospecific intermolecular alkene hydrosilylation leading to the asymmetrically tetrasubstituted silanes. A wide range of dihydrosilanes and alkenes displaying various functional groups are compatible with this process, giving access to a variety of highly functionalized silicon-stereogenic dihydrobenzosiloles in good to excellent yields and enantioselectivities.

The existing moisture in shale samples makes the evaluation for shale gas reservoirs more difficult due to its impact on the methane adsorption capacity and pore structure measurements. This paper compares the pore structure characteristics and methane adsorption capacity between dry and wet shale samples from Perth Basin, Western Australia. Pores with size between 0.4 nm and 100 nm were quantified by low-pressure N2 and CO2 adsorption. The comparative results demonstrate that moisture could alter the pore size distribution for big pores (>16 nm) and small pores (0.4–16 nm) in different ways. For each sample, the moisture effect on methane adsorption in shales changes with pressure: moisture effect on methane adsorption is more pronounced at lower pressure than higher pressure. For all samples, the effect of moisture on methane adsorption is related to the total organic carbon (TOC) content. Moisture could reduce methane adsorption by blocking clay- hosted small pores directly and organic matter-hosted small pores indirectly in high TOC samples. This phenomenon can effectively lead to a reduced Langmuir volume (VL) and increased Langmuir pressure (PL) when moisture exists.

A large amount of fracturing fluid enters a well of a shale gas reservoir to create a fracture network, but the recovery of fracturing fluid is generally less than 30%. Fracturing fluid from the hy...

Spontaneous microfracture propagation caused by mineral crystallization or growth has been demonstrated in a variety of volume-increasing mineral replacement reactions. This brings a new look on th...

Capillary pressure curve plays a critical role in the reservoir evaluation. It is essential to reconstruct and predict capillary pressure curve properly. Many traditional capillary pressure correlations have been suggested in the literature. However, their major limitation is mainly applicable to homogenous reservoir, and the larger error will be caused when heterogeneous reservoir is dealt by using these mathematical correlations. This study aims at providing an important method based on Particle Swarm Optimization-Back Propagation Neural Network (PSO-BP neural network) to represent and predict capillary pressure curve for homogenous and heterogeneous reservoir. The combination of PSO algorithm and BP neural network converges quickly, which improves the accuracy and efficiency of simulation. In this paper, core samples from three blocks of the same marine-sand reservoir, whose porosity is between 0.6% and 20.0% and permeability is between 0.1mD and 6117mD, are investigated by PSO-BP neural network method and J-Function method respectively. The reconstruction and prediction results are compared with the results obtained by mercury intrusion method in laboratory. The results show that capillary pressure curves reconstructed and predicted by PSO-BP neural network method are in better agreement with mercury intrusion curves than J-Function method, with 0.1%–5% and 5%–8% relative error respectively, which can totally meet the in-situ requirements. It is also demonstrated that PSO-BP neural network method is more suitable for homogenous and heterogeneous reservoir. Keywords: Capillary pressure curve, Homogenous reservoir, Heterogeneous reservoir, PSO-BP neural network, Mercury intrusion

Shale gas reservoirs are characterized by nano-Darcy permeability, rich organic matter, ultralow water saturation, developed bedding, and micro-fractures, leading to multi-scale transportation of shale gas. Multistage fracturing of horizontal wells is the main development technology to stimulate shale gas reservoirs, and tens of thousands of cubic meters of fluids are injected into the reservoir. Retention and flowback of fracturing fluids on gas transfer plays an important role on the effect of hydraulic fracturing. Through the analysis of geological and engineering factors controlling water imbibition and diffusion in shale gas reservoirs, the mechanisms of low recovery of fracturing fluids and the reasons that some shale gas wells with low recovery of fracturing fluids have high gas production rate were revealed. This paper carried out a series of experiments of the fluid imbibition and fracture initiation in the shale selected from the Longmaxi Formation in Sichuan basin. In detail, this paper investigated imbibition and dispersion the fluid in shale and analyzed the mechanisms of the shale-water interactions causing the reduction of shale strength and fracture initiation and propagation. Based on the field case studies of well shut-in after fracturing, its influence on the well production was assessed. Formation damage caused by fracturing fluid is multi-scale, and the evaluation of formation damage caused by fracturing fluids should take the influence on the gas transmission capacity into consideration, and residual fracturing fluids may have a positive effect on gas transfer. It should take the long-term stable production of shale gas well and the effect of fracturing fluids transmission on gas multi-scale transport into consideration when determining the timing and pressure difference of fracturing fluids flowback from shale gas reservoirs.

Developed fractures are beneficial for the efficient development of tight reservoir. But they also lead to formation damage induced by particle capture in fractures during drill-in fluid loss. Effective modelling of particle transport and capture behavior is critical to the prediction and prevention of formation damage. However, the behaviors of particulate suspension transport in fractured media are still incompletely understood and quantified. This paper develops stochastic microscale model for size-exclusion particulate-suspension transport in fractured media. The proposed model accounts for the fracture network connectivity and its subsequent evolution due to particle capture by the introduction of percolation theory. It accounts for the particle capture probability and accessible flux in the expression for particle capture and fracture plugging dynamics. The micro-stochastic model allows for upscaling and numerical solution is obtained for the macroscale equation system to predict the rate and range of formation damage induced by drill-in fluid loss. Laboratory experiments are conducted for the model validation. Modelling results exhibit preferential plugging of fractures with size equal to or below the suspended particle size. The fractures with width equal to the particle diameter decrease fastest. The captured particle concentration decreases with the improvement of the network connectivity. Higher network connectivity leads to smaller decrease of fracture concentration and network permeability during the transport and capture of the same size of suspended particles. The proposed model shows a good agreement with laboratory data.

Field observations have shown that the concentration of fines produced during the early two-phase flow stage in coalbed methane (CBM) reservoirs is much higher than single-phase water flow, leading to more frequent workover activities. The typical flow pattern in early two-phase flow is bubble-water flow, in which the liquid phase is mostly contained in the form of liquid “plugs”, separated by a series of moving bubbles/gas-water interfaces (GWIs). Here, we quantify the impact of moving bubbles/GWIs on fines detachment, aiming at better understanding of fines mobilization mechanisms in bubble-water flow towards their effective control. First, fines migration tests in the absence and presence of moving bubbles in water flow, including effluent and permeability measurements, were conducted on fractured coal plugs. The experimental flow velocity was less than the critical flow velocity (CFV) for massive fines release. Experimental results showed that both peak effluent concentration and permeability impairment in the presence of moving bubbles were much greater than when absent, indicating that the quantity of fines detached by moving bubbles/GIWs was much larger than simply by water flow. Second, forces and torques acting on coal fines were analyzed to determine the combined effects of extended Derjaguin-Landau-Verwey-Overlook (DLVO), hydrodynamic, surface tension, and frictional forces on fines mobilization. Theoretical results showed that all in-situ fines could be mobilized by moving GWIs, whereas no fines could be released by water flow when the flow velocity is smaller than the CFV, as the surface tension force arising from passing GWIs greatly dominates hydrodynamic forces by 2–4 orders of magnitude. Theoretical results support experimental data, in spite of some errors due to model assumptions, i.e., spherical fines and homogenous surface.

The stability of the horizontal long section of a wellbore is the main restriction of efficient development of shale gas. The use of oil-based drilling fluids in the initial stage of Longmaxi shale gas exploration in the Southern Sichuan Basin, China still causes wellbore collapses for reasons not well understood. Based on the geological characteristics and engineering conditions of brittle shale, a significant factor influencing shale wellbore stability-friction coefficient is proposed. Due to the developed facture networks of brittle shale in this region, frictional sliding along the fracture surface is the main source of movement within the Longmaxi Formation. Here, we determined the effects of drilling fluids on the Longmaxi Formation shale in Southern Sichuan Basin. Natural fractures slide due to compression shear slip, and the friction coefficient of the fracture surfaces is a controllable factor of shear and slip in natural fractures in shales. The typical experimental apparatus of rock friction sliding was modified to accommodate for drilling fluids and typical in-situ temperatures. Results show that the friction coefficient decreases, induced by infiltration of drilling fluids filtrate, and the friction coefficient is more sensitive to oil-based drilling fluid filtrate than water-based. The high-pH oil-based drilling fluid filtrate shortens the length of time taken by static friction stage, and smooths the time vs friction coefficient curve, which creates an easier situation for frictional sliding. High viscosity and good wettability lead to the strong lubricity of oil-based drilling fluid. The surface properties of the shale samples changed after the high alkalinity fluid immersion, such as fracture surface planarization, and floc-like particle generation, causing an obvious reduction of friction coefficient between fracture surfaces. As a result of rock strength decreasing after immersion into drilling fluids filtrate, asperities on fracture surface were prone to shear failure in the process of frictional sliding, and their failure products migrated with the fracture surface movement. This not only decreased the roughness shale surface but also acted as a friction reduction agent between the sliding surfaces. This study provides theoretical guidance for drilling fluid selection and optimization during brittle shale well drilling.

In this study, the FPA90-Cl resin was magnetized with supported Fe3O4 particles using a chemical co-precipitation method and its removal performance of bromate and coexisting precursors was explored. The magnetized FPA90-Cl resin was structurally characterized by SEM, FT-IR, and XRD. The effects of the initial concentrations, temperature, and resin dosage on bromate and bromide ion removal in drinking water were investigated using batch experiments. The magnetized FPA90-Cl resin exhibited a high removal efficiency for bromate and bromide ions at three initial concentrations, and the residual bromate concentrations were under the maximum contaminant level (MCL) of 10 μg L−1 after 80 min. The adsorption data of bromate and bromide ion could be well described by a pseudo-first-order kinetic model (R2 ˃ 0.98). The bromate removal alone was further studied by varying the initial solution pH, temperature, and competitive anions. The results showed that the magnetized FPA90-Cl resin could be used over a wide pH range (4.0–9.0). The maximum sorption capacity of the magnetized FPA90-Cl resin for bromate reached 132.83 mg g−1 at 298 K. The Freundlich and Redlich-Peterson isotherm models fit the bromate adsorption equilibrium better (R2 ˃ 0.99) than the Langmuir isotherm model (R2 ˃ 0.98). The thermodynamic analysis showed that the bromate adsorption process was endothermic. The negative ΔG and positive ΔS indicated that the process was spontaneous and that randomness increased after adsorption, respectively. The competition of coexisting anions with bromate was in the order of SO42− > CO32− > Cl− > NO3− > HCO3− > PO43−. Additionally, the magnetized FPA90-Cl resin could maintain a high bromate and bromide ion adsorption capacity after five cycles of regeneration by a 0.1 M NaCl solution.

Porosity and permeability stress-sensitive behavior of sandstone is investigated through porosity and permeability measurements under hydrostatic compression. An empirical logarithm model is applied to the evaluation of stress sensitivity. Mercury injection, casting thin sections and scanning electron microscope are adopted to discuss the microscopic controlling factors and mechanisms of stress-sensitive behavior of sandstone. Disparities between laboratory-scale and field-scale data are also discussed. Experimental results show that both porosity and permeability decrease with increasing effective stress, and permeability is more sensitive to stress. The evolution of porosity and permeability with increasing effective stress follows the logarithmic model and can be classified into three stages: rapid decline, moderative decline and stable-slight decline stage. Stronger permeability stress sensitivity is observed in specimens with lower initial porosity and permeability, which is fundamentally controlled by the size and shape of void spaces as well as the content and distribution of soft minerals. While porosity stress sensitivity is observed to be discrete. Pore throat with small aspect ratio and irregular shape, fractures and minerals with lower elasticity modulus lead to the increase in permeability stress sensitivity of sandstone. The stress sensitivity characteristics are essentially the result of the dissimilar deformation responses of pores and framework grains under effective stress. Stress sensitivity evaluated in the laboratory usually does not completely represent the stress sensitivity in the field, due to stress release, drilling induced fractures and the difference of experimental and in situ conditions.

Encoded microsphere suspension array is promising for multiplex bioassay. Novel high quality phenolic resin (PR) microspheres encoded by Fluorescence and Surface Enhanced Raman Spectra (SERS) were fabricated in the present work. The PR microspheres possessed autofluorescence property and could be jointly encoded with other fluorescent molecules including fluorescein isothiocyanate. The fluorescent encoded PR microspheres were modified with Ag nanoparticles and Raman label molecules for combination of SERS encoding, which is rarely reported. The dual-mode encoded microspheres were evaluated by MTT assay and flow cytometry. The results showed the high quality encoded microspheres presented promising application prospect in biomarker and detection of antibody, DNA and RNA.

Transition-metal-free arylation of benzoxazoles with aryl nitriles has been developed to afford important 2-aryl benzoxazoles under simple reaction conditions. A variety of functional groups were tolerated and heteroaryl nitriles were also suitable substrates. Preliminary mechanistic studies indicated a ring-opening mechanism. The methylation of azoles with acetonitrile was also achieved in a similar manner. This protocol provides a novel strategy for the efficient synthesis of complex 2-aryl benzoxazole derivatives.

A new eco-friendly adsorbent (ACKGM) derived from konjac glucomannan was prepared and used for Cr(VI) adsorption from aqueous solution. The ACKGM was synthesized by amino-modification of cross-linked konjac glucomannan through nucleophilic substitution approach. The adsorbent was characterized by scanning electron microscopy and Fourier Transform Infrared spectroscopy. The ACKGM possessed property of fast adsorption and over 92% of Cr(VI) was adsorbed in the first 10 min. The adsorption equilibrium was reached in 45 min. The ACKGM removed 99.98%–85.93% of Cr(VI) when initial Cr(VI) concentration varied in 20–150 mg/L. It was found the absorption depended on pH and the optimum adsorption took place at pH = 2. The maximum adsorption capacity was 34.1 mg/g, when the dosage of ACKGM was 2.0 g/L at 30 °C. The adsorption kinetics followed the pseudo-second order kinetics equation and the activation energy (Ea) of the adsorption was 32.72 kJ/mol. Different isotherm models were used to analyze the isotherms of the adsorption. The adsorption isotherms fitted best with the Redlich–Peterson isotherm equation. The enthalpy change (ΔH0) of adsorption was − 23.21 kJ/mol. The thermodynamic parameters showed the adsorption of Cr(VI) onto ACKGM was a spontaneous and exothermic process. The adsorption mechanism study showed that electrostatic attraction, affinity interaction and polymer inclusion and net trapping mechanisms were involved in the process. The present study suggests that the ACKGM is an effective adsorbent for the removal of Cr(VI) from aqueous solution.

The working fluid used for gas drilling and the excessive differences in production pressure during the gas production process causes repeated fluctuations between increasing and decreasing water saturation of the rock. These repeated fluctuations result in dry-wet state alternations of the rock, which weakens the rock strength. Weakening rock strength will lead to sand shedding, which damages reservoirs because of particle migration, solid blockage, and sand production. This will also change the stress sensitivity of deep tight sandstone, thus affecting gas well production. Therefore, this study conducted both a dry-wet alternation experiment and a stress sensitivity experiment after dry-wet alternation using deep tight sandstone. During the experiment, the changes of the rock dynamic Young's modulus, Poisson's ratio, and stress sensitivity coefficient were monitored. The experimental results show that the dynamic Young's modulus and Poisson's ratio of rock samples decreased after dry-wet alternations. Furthermore, these alternations increase the stress sensitivity of the rock matrix and weaken the stress sensitivity of fractured rock samples.

Oxidizing stimulation of organic-rich shale was proposed to enhance the rate of methane extraction from the matrix. Previous studies lacked attention on the dissolution characteristics of organic matter (OM) during the dissolution process performed using oxidative fluids. In this study, the organic-rich shale samples obtained from the Longmaxi Formation, Niutitang Formation, and Yanchang Formation were used for dissolution experiments. Crushed shale samples were treated with deionized water, hydrogen peroxide (H2O2), or sodium hypochlorite (NaClO) for 240 h, respectively. By using a combination of X-ray Diffraction, rock-eval pyrolysis, total organic carbon analysis, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, the composition and organic geochemical characteristics of the treated shale samples were determined. The results showed that H2O2 induces the dissolution of both the pyrite and carbonate minerals, and NaClO more readily dissolves pyrite and not carbonate minerals. Higher removal efficiency of OM for all four shale samples occurs when treated with NaClO than with H2O2. The oxidative dissolution of OM in these shale samples occurs as two dominant modes: one is the oxidation cracking of C–C, C–H such as in the Niutitang or Yanchange formations; the other is oxidation cracking of C–O, such as in the Longmaxi Formation samples. Both the Longmaxi Formation samples, which showed higher C–O contents compared to samples from the other two formations, exhibited better oxidizability than others when treated with H2O2 or NaClO. Oxidation products such as Fe2+/Fe3+ and H+ enhance the oxidizing ability of H2O2 and NaClO toward cracking of OM. However, the consumption of H+ due to the carbonate minerals may impair the oxidizing ability of H2O2, but not that of NaClO. Furthermore, the presence of an organo-clay complex has an adverse influence on the removal of OM. The results indicated that the type of OM, the content of the pyrite and carbonated minerals, and the physical protection of the organic carbon by clays should be taken into account, when selecting a shale reservoir suitable for oxidizing stimulation and associated optimization of the oxidant during the fracturing operation design.

In the present work, optimization of microwave-assisted extraction of polysaccharides from Sargassum thunbergii was investigated. The physicochemical properties, structural characteristics, and in vitro antioxidant and hypoglycemic activities were determined. The optimal extraction conditions with a yield of 2.84±0.09% for extraction of polysaccharides (STP-1) were extraction time 23min, microwave power 547W, extraction temperature 80°C, and the ratio of raw material to water 1:27g/mL. STP-1 contained 32.7% of total carbohydrate, 1.86% of protein, and 15.2% of sulfates. STP-1 had a major molecular weight of 190.4kDa, and comprised of arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid with molar percentages of 1.94, 30.7, 4.54, 23.2, 17.6, 8.11, and 13.9%, respectively. In addition, STP-1 showed strong antioxidant and α-glucosidase inhibitory activities, and could improve the glucose uptake in insulin-resistant HepG2 cells, suggesting that STP-1 can be exploited as a promising natural antioxidant and hypoglycemic agent.

Sugarcane bagasse, one of the most abundant agro-food by-products, is a very promising raw material available at low cost for recovering bioactive substances. In this study, the total phenolic content was measured by Folin-Ciocalteu method and the antioxidant activity of the extracts was determined by DPPH , ABTS + and ROO (ORAC) methods. The results indicated that 30% hydroalcoholic fraction (30%E) had the highest total phenolic content (170.68 ± 3.25 mg GAE/g DW) among the hydroalcoholic extracts and was the most active fraction in antioxidant activity. Besides, intestinal α-glucosidase inhibitory activity was conducted to assess the antihyperglycemic ability of the extracts and 30%E showed a significant effect at 10 mg/mL (82.64% inhibition of sucrase and 74.26% inhibition of maltase, respectively). Glucose uptake assay based on HepG2 cells was used to evaluate the glucose uptake effect of 30%E. Five phenolic compounds (tricin 4- O -guaiacylglyceryl ether-7- O -glucopyranoside, genistin, p -coumaric acid, quercetin and genistein) were identified in 30%E using UHPLC-HR-TOFMS. Taken together, the data indicated that sugarcane bagasse can be used as a potential source of bio-active phenolics and may play a role in functional agents exploitation and agro-industrial revenue increase.

In order to explore the damage mechanisms and improve the method to evaluate and optimize the performance of formation damage control of oil-based drill-in fluids, this paper took an ultra-deep fractured tight gas reservoir in piedmont configuration, located in the Cretaceous Bashijiqike Fm of the Tarim Basin, as an example. First, evaluation experiments were conducted on the filtrate invasion, the dynamic damage of oil-based drill-in fluids and the loading capacity of filter cakes. Meanwhile, the evaluating methods were optimized for the formation damage control effect of oil-based drill-in fluids in laboratory: pre-processing drill-in fluids before grading analysis; using the dynamic damage method to simulate the damage process for evaluating the percentage of regained permeability; and evaluating the loading capacity of filter cakes. The experimental results show that (1) oil phase trapping damage and solid phase invasion are the main formation damage types; (2) the damage degree of filtrate is the strongest on the matrix; and (3) the dynamic damage degree of oil-based drill-in fluids reaches medium strong to strong on fractures and filter cakes show a good sealing capacity for the fractures less than 100 μm. In conclusion, the filter cakes' loading capacity should be first guaranteed, and both percentage of regained permeability and liquid trapping damage degree should be both considered in the oil-based drill-in fluids prepared for those ultra-deep fractured tight sandstone gas reservoirs.

Fines migration has posed a great challenge to gas and water production in CBM reservoirs, resulting not only in dramatic permeability reduction but also in excessive wear on equipment. The objective of this study was to investigate critical flow conditions for massive fines detachment in the dewatering phase, for the purpose of yielding an improved understanding of fines detachment mechanisms and their effective control in the field. First, fines migration experiments under saturated conditions, including effluent concentration and permeability measurements, were conducted at elevated pressure gradients on fractured coal samples with various apertures. Experimental results indicate the existence of a critical pressure gradient (CPG) for massive fines detachment. Second, a mathematical model was developed to describe single particle detachment in the fracture, accounting for the coupling effects of hydrodynamic and extended-DLVO forces. Effects of fines size and fracture aperture on fines detachment were ...

Summary Drill-in fluid loss is the most important cause of formation damage during the drill-in process in fractured tight reservoirs. The addition of lost-circulation material (LCM) into drill-in fluid is the most popular technique for loss control. However, traditional LCM selection is mainly performed by use of the trial-and-error method because of the lack of mathematical models. The present work aims at filling this gap by developing a new mathematical model to characterize the performance of drill-in fluid-loss control by use of LCM during the drill-in process of fractured tight reservoirs. Plugging-zone strength and fracture-propagation pressure are the two main factors affecting drill-in fluid-loss control. The developed mathematical model consists of two submodels: the plugging-zone-strength model and the fracture-propagation-pressure model. Explicit formulae are obtained for LCM selection dependent on the proposed model to control drill-in fluid loss and prevent formation damage. Effects of LCM mechanical and geometrical properties on loss-control performance are analyzed for optimal fracture plugging and propagation control. Laboratory tests on loss-control effect by use of different types and concentrations of LCMs are performed. Different combinations of acid-soluble rigid particles, fibers, and elastic particles are tested to generate a synergy effect for drill-in fluid-loss control. The derived model is validated by laboratory data and successfully applied to the field case study in Sichuan Basin, China.

In shale gas plays, both the permeability and diffusion coefficient are indispensible parameters to reservoir assessment and production forecast. Unlike previous works which measured the two parameters individually, this paper first proposed an integrated method of measuring the gas permeability and diffusion coefficient simultaneously with a single pressure decay curve. The experiments were conducted through one-chamber pressure decay tests (PDT) with shale core plugs under stressful conditions, simplifying the apparatus and time saving. According to the gas transport mechanisms, the whole gas flow in shale plugs was divided into three stages: viscous and slip flow stage (stage I ), non-surface diffusion stage (stage II ), and surface diffusion stage (stage III ). Then using the linear permeability and bidisperse diffusion models, the permeability was calculated to be on the order of 10 − 5 mD, and the effective diffusion coefficients ( D / r 2 ) of stages II and III were about 10 − 5 s − 1 and 10 − 7 s − 1 , respectively, which got well agreements with the existed methods. Given that the multiple gas transport stages in shale are actually interacted and coupled with each other, the integrated measuring values in this paper may be more representative.

A cationic polysaccharide (CDCS) derived from dextran and chitosan was fabricated by crosslinking method as an eco-friendly flocculant. The flocculant was characterized by thermogravimetric analysis and Fourier transform infrared spectroscopy. Influences of temperature, pH and flocculant dosage on flocculation efficiency were examined. The CDCS presented enhanced high flocculation properties in a wide pH range conditions. In kaolin suspension, when pH was in the rang of 3–7, the flocculation efficiency was over 96.9% with dosage below 5 mg/L. In alkaline condition, it also presented a high flocculation efficiency of 98.2% (pH = 9) and 93.7% (pH = 11) with a low dosage of 7 and 17 mg/L, respectively. The flocculation efficiency decreased as the temperature rose from 10 to 40∘C. For actual wastewater treatment, the CDCS flocculant performed much better than commercial polyacrylamide and ferric sulfate. It removed 97.7% of the solid suspended particles in the wastewater. The flocculant mechanism study suggested charge neutralization, adsorption bridging and sweeping flocculant mechanisms were included in the flocculation process. The flocculant CDCS exhibited a broad prospects for wastewater treatment.

Shales (illite was the dominant clay mineral) of Silurian Longmaxi Formation in Sichuan Basin and Triassic Yanchang Formation in Ordos Basin were taken as subjects to examine the mechanisms of shale-water interaction, quantitative characterization of hydration force and potential field applications based on micro forces analyses. Mica sheet with composition and property very similar to illite was tested for micro forces between the crystal layers. In electrolyte solution, micro forces between mica-solution-mica system include DLVO (Derjaguin-Landau-Verwey-Overbeek) force and hydration force; when the electrolyte concentration was low, the tested curve agreed with the theoretical DLVO curve; when the electrolyte concentration was higher than the critical value and the distance between mica sheets was less than 5 nm, the tested curve deviated from the DLVO curve completely, and the hydration force became dominant. Quantitative analysis indicated that the hydration force decayed in a rapid double-exponential type with the growth of distance. Field applications indicate that strict control of water invasion and reducing the strength of hydration force are the keys in designing collapse-preventing drilling fluids; meanwhile, during the shut-in period of shale gas wells, shale-water interaction can induce and extend micro-cracks, further improving the stimulation effect of shale reservoirs. Key words: shale, hydration force, illite, wellbore collapse, well shut-in

Owing to the presence of chemically unstable compositions (e.g., clay minerals, carbonate, pyrite, and organic matter (OM)) which are closely related to shale structure failures or dissolution pores, the methods to increase gas well long-term productivity from tight shale matrix need to take into account the chemical interaction of shale with injected fluid. In this study, black shale samples obtained from Lower Silurian Longmaxi formation in Sichuan basin, China were treated with 15 wt% hydrogen peroxide (H2O2) for the comprehensive understanding of the change in shale composition and the associated dissolution structures. The measurements of mass loss, total organic carbon content, and mineralogical composition showed that carbonate, reductive inorganic minerals containing ferrous iron (e.g., pyrite and chlorite), and OM in samples exhibited strong dissolution; however, the other minerals behaved in a non-reactive manner at the experimental time scale. After the oxidative treatment for 240 h, a large amount of oxidation-induced fractures and dissolution pores were observed by field-emission scanning electron microscopy. The fractures mainly oriented parallel to lamination were attributed to the dissolution of OM and structural alteration of clay minerals. All the dissolution pores seemed to be strongly dependent on the loss of dolomite, pyrite, and OM. Results from high-pressure mercury intrusion and low-pressure nitrogen adsorption analysis showed that these dissolution pores ranging from 10 to 500 nm in diameter exhibited a significant increase in pore volume due to the removal of interconnected pore-filling OM, while the volume of pores > 1 μm in size exhibited a minor increase because the micrometer-size dissolved particles appeared to be discrete or unconnected. Thus the oxidative dissolution could lead to the higher porosity and better connectivity of nanometer-size pore networks in shale samples. The induced fractures reduced the size of diffusion dominant zones in shale matrix, and the dissolution pores increased the size of gas transport pathways into fractures. These results indicate that the injection of H2O2 may play an important role in shale matrix stimulation by oxidative dissolution which is likely to improve matrix diffusivity.

A novel urea-formaldehyde (UF) monolithic column has been developed and exploited as a sorbent for hydrophilic in-tube solid-phase microextraction (in-tube SPME) of aminoglycosides (AGs). Because of the innate hydrophilicity, UF monolith showed high extraction efficiency towards these hydrophilic analytes. The adsorption capacities for target compounds dissolved in water/ACN (1:1, v/v) were in the range of 5.18-7.36μg/cm. Due to the lack of a chromophore, evaporative light scattering detector (ELSD) was selected as the detector for AGs, and coupled with the online in-tube SPME-HPLC system. Several factors of the online system, such as trifluoroacetic acid (TFA) and ACN percentage in the sampling solution, ionic strength in the sample solution, elution volume, sampling and elution flow rate, were optimized with respect to the extraction efficiencies. Under the optimized conditions, the limits of detection (LODs) of streptomycin, tobramycin and neomycin were discovered in the range of 3.0-5.2μg/kg. The recoveries were ranged from 82.1 to 96.7% with relative standard deviations (RSDs) of 2.3-5.1% (n=4) at spiking levels of 50, 200 and 500μg/kg, respectively. The excellent applicability of the UF monolithic column was examined by the determination of streptomycin in practical tilapia samples, which showed the potential advantages for the analysis of polar analytes in complicated samples.

Magnetic hollow carbon microspheres (MHCMs) were fabricated with a dual alternative constitution of cavities and porous carbon shells by a combination of microwave-assistant polycondensation and surfactant-free emulsion polymerization. The MHCM was characterized by transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometry and N2 adsorption/desorption isotherms. The MHCMs possessed features of uniform morphologies, high surface area (680 m2 g−1), large pore volume (0.61 cm3 g−1) and magnetic responsiveness. The MHCMs were used as an adsorbent to remove rhodamine B (RB). The removal efficiency of RB reached 99.5% and the adsorption capacity of the MHCMs reached as high as 300 mg g−1. The adsorption process followed the Langmuir isotherm very well. The enthalpy change was 28.35 kJ mol−1. The negative free energy change indicated that the adsorption process was feasible and spontaneous. The positive entropy change showed that there was an increase in disorder in the adsorption system. The removal process was endothermic and interaction controlled. The adsorption kinetics fitted well with the pseudo-second-order kinetics model. The removal efficiency of RB remained over 90% after six consecutive cycles, which demonstrated the high adsorption performance and favourable reusability of the MHCMs.

Summary Appropriate exposure to sun is beneficial to humans and living organisms. However, excessive exposure to ultraviolet (UV) radiation can lead to photoageing, severe health risks and even death. Nowadays, the health risks of excess UV exposure have greatly increased due to the significant changes of global climate and human lifestyle as well as the thinning of the stratospheric ozone (a natural and effective filter for solar UV radiation). Therefore, protecting against UV radiation-induced damage is a serious challenge. Research needs to address the understanding of the mechanisms underlying the UV-induced damages and also explore the potential use of natural substances to combat the harm caused by UV radiation. Plant-based substances have been found to exert significant protective effects against UV radiation. This review explores the most recent hypothesis of natural bioactive compounds (such as flavones, peptides, polysaccharides and terpenoids) as potential protective agents against UV radiation. The similarities and differences in UV photoprotective mechanisms among these different classes of compounds are also discussed.

The therapeutic benefits of whole grains on diabetes mellitus have been continuously confirmed by in-depth research. To date, limited studies have investigated the effect of extruded products of whole grains on the insulin signaling pathway in vivo. This study investigated the effects of oral consumption of whole grain extrudate, including 97% brown rice and 3% defatted rice bran (w/w, BRD), on glucose metabolism and the hepatic insulin signaling pathway in C57BL/KsJ-db/db mice. BRD treatment induced a remarkable reduction in blood glucose. Moreover, glucose intolerance and insulin resistance were ameliorated in the BRD-treated group compared with those in the db/db control group. BRD also increased the hepatic glycogen content by reducing the expression and increasing the phosphorylation of glycogen synthase kinase 3β (GSK3β). The activities of glucose-6-phosphatase and phosphoenolpyruvate carboxylase and their respective mRNA expression levels in the liver were simultaneously decreased in the BRD-treated group. BRD also significantly upregulated the expression of phosphatidylinositol 3-kinase (PI3K) and increased the phosphorylation of insulin receptor substrate 1 (IRS1) and protein kinase B (AKT). These results indicate that BRD exhibits antidiabetic potential by activating the IRS1/PI3K/AKT signaling pathway, further regulating the expression of the FOXO1 gene and p-GSK3β protein, thus inhibiting hepatic gluconeogenesis, increasing hepatic glycogen storage, and improving insulin resistance. Therefore, BRD could be used as a functional ingredient to alleviate the symptoms of hyperglycemia.

Formation damage induced by lost circulation delayed the exploration and development of fractured oil and gas reservoirs. It is the main way to control the lost circulation of fractured tight reservoirs by using lost circulation material(LCM) to plugging the fracture. The LCM selection method is based on trial and error, lack of scientific basis. This work fills the gap. In the current paper, the impacts of multi-factors such as particle size distribution, flow rate, LCM geometric properties, particle concentration, roughness of facture surface are investigated by means of theoretical analysis and laboratory experiments. Grain size distribution analysis, roundness tests, SEM images, are conducted with spherical and flaky materials. Then, based on rough fractured surface preparation, solid phase suspension preparation, suspension concentration monitoring, injection pressure monitoring, the transport and capture of LCM under different influencing factors are evaluated. The experimental results show: The effect of fracture surface roughness on the captures behaviour of solid particles in fractures was revealed. In the course of the migration of solid particles, irregular projections on the surface of the fracture increase the resistance of solid particles during migration. The rougher the surface of fractures, the more complex the undulations, and the greater the resistance to migration of solid particles. The probability of detention is also large, and it is easier to form plugging. With the concentration of the injected particles increasing, the solid phase capture rate in the fracture increases. Particle size distribution has an effect on the capture behaviour of spherical and flaky materials, but it has a significant effect on the capture behaviour of spherical materials; At the same particle size, the flaky material has a higher capture probability than the spherical material in the fracture.

Plugging natural fractures with lost control materials (LCMs) is the common method to prevent foramtion damage and control fluids loss in In naturally fractured reservoir. The plugging zone strenfth stability is critically important for maintaining long-term plugging quality. Surface friction coefficient (SFC) is proposed as an important parameter for the selection of LCMs based on based on granular matter mechanics and the instability of plugging zone. The force chain network with specific geometry is the basis of the plugging zone strength and supporting external load. The likelihood of shear failure can be increased by decline of SFC. And high strength of force chain can not be formed and it can relatively easy to be broken even if a small shear is applied. Effects of LCMs particle size distribution, circulation abrasion, LCMs combination, working fluids infiltration, and high temperature aging on friction behaviors are analyzed for LCMs with high SFC selection. Results show that the average SFC shows a decreasing trend with the particle size reduction and the difficulty of particle dislocation decreases with the particle size reduction. For deep naturally fractured reservoirs, particle size will degradate due to long-term drilling fluid circulation in the wellbore, thus affecting the plugging effect of drill-in fluid. The mixture of elastic material and fiber into rigid material increases the SFC and elastic material contributes most to the increasing the SFC. The SFC decreases under the condition of fluids infiltration, and the SFC show a higher decline in oil-based condition. The high-temperature aging makes the edge of the organic rigid material more smooth, which reduces its SFC.

Cyanidin-3-glucoside is a major anthocyanin in legumes, black rice, and purple potato, and has anti-inflammatory and antioxidant properties. In the present study, the effect of acylation on cyanidin-3-glucoside lipophilicity, stability, and antioxidant capacity was investigated. Cyanidin-3-glucoside was enzymatically acylated through transesterification with fatty acid esters to produce three monoacylated cyanidin-3-glucoside esters, cyanidin-3-(6″-n-octanoyl)-glucoside, cyanidin-3-(6″-lauroyl)-glucoside, and cyanidin-3-(6″-myristoyl)-glucoside. Cyanidin-3-(6″-n-octanoyl)-glucoside had the highest thermostability and photostability of the three cyanidin-3-glucoside esters. While the in vitro antioxidant activity of cyanidin-3-(6″-n-octanoyl)-glucoside was 7.5%-14.3% lower than that of cyanidin-3-glucoside (p 0.05), its cellular antioxidant activity increased by 33.3% (p 0.05). Further, while cyanidin-3-(6″-lauroyl)-glucoside had lower stability and in vitro antioxidant activity than that of cyanidin-3-(6″-n-octanoyl)-glucoside, its cellular antioxidant capacity was 125.9% and 69.4% higher than cyanidin-3-glucoside and cyanidin-3-(6″-n-octanoyl)-glucoside, respectively (p 0.05). This study demonstrated that transesterification can be used to improve the stability and in vivo antioxidant activity of cyanidin-3-glucoside.