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In recent years, environmental pollution and resource waste have become the focus of heated discussion around the world. In order to realize green and sustainable development, the development of green supply chain (GSC) has attracted the attention of many scholars. The research object of this paper is the dual-channel green supply chain (DGSC) composed of online channels and offline channels. The supplier is the leader of the entire DGSC, and it needs to optimize the wholesale price of the product and the level of green investment to maximize its own benefit. In addition, the supplier also needs to establish contracts with network sales platform (NSP) and store sales platform (SSP) to increase the benefit of NSP and SSP, and ultimately increase the benefit level of the entire DGSC. Among them, we constructed a centralized decision (CD) model and a decentralized decision (DD) model, and obtained the optimal pricing, optimal greenness and optimal benefit of the supplier, NSP and SSP under the two models. We found that the benefits of SC members under the DD model are generally lower than those of the CC model. Therefore, we built contracts between the supplier, NSP and SSP to coordinate. Finally, we substituted specific parameters to verify the model. The following conclusions are drawn: (i) When consumers prefer online sales channels, it will positively affect the online sales price, online sales volume and greenness level of DGSC. At the same time, it negatively affects offline sales price and sales volume. (ii) The benefit of DGSC and the benefit of NSP, SSP, and the supplier show a phenomenon of decline first and then increase with respect to consumers’ preference for online sales channels. (iii) Under the coordination contract, the subsidy factor positively affects the benefits of the supplier and online and offline wholesale prices, and negatively affects the benefits of online platforms and physical stores.

Shale oil had attracted worldwide attention due to its vast volume, according to statistics, technical recovery of shale oil worldwide exceeded 250billion ton, mostly located in America, Africa and north Asia. However shale oil was characterized by its high viscosity, deep reservoir location, posing threats to the operator, traditional rod-pump artificial lift was not a good choice due to the friction issue, How to walk out of those challenges were worth thinking, while rod free artificial lift methods had been field proven in the oilfield, its progress would give us some inspirations[1]. In this paper, rod free artificial lift methods including downhole motivated reciprocating pump, centrifugal pump and progressing cavity pump were discussed, some technological highlights such as pulling and running electric cables, host SCADA system and production control algorism had been introduced in detail. Finally the efficacy of rodless artificial lift was analyzed from the perspective of investment

International audience; Development of reliable sensing strategy combining surface-enhanced Raman scattering (SERS) and surface-assisted laser desorption/ionization-mass spectrometry (SALDI-MS) is of significant interest to distinguish cysteine enantiomers in body fluid for understanding their physiological roles and toxicity hazards. In this work, a SERS/SALDI-MS dual-mode sensing platform of gold nanoparticles (Au NPs) decorated holey carbon nitride (hg-C3N4) was fabricated for sensitive detecting cysteine. The designed Au@hg-C3N4 matrix featured a uniform distribution of Au NPs with the help of anchoring effect of hg-C3N4 holey structure, which was conducive to produce highly repeatable signals. Moreover, the combination of Au NPs and holey g-C3N4 endowed this matrix with superior enrichment capacity, enhanced charge transfer and strong UV absorption. These merits allowed the matrix to acquire high sensitivity and enhanced reproducibility for l-cysteine by means of SERS/SALDI-MS. Likewise, reliable detection of l-cysteine and efficient recognition of d-cysteine in human serum jointly revealed its prospect for detecting cysteine enantiomers in body fluids. This work offers a reliable SERS/SALDI-MS strategy for determining L/D-cysteine enantiomers, and the designed Au@hg-C3N4 matrix becomes a potential application candidate for selective detection of bio-enantiomers.

The photoluminescent (PL) properties of lanthanide metal-organic frameworks (Ln-MOFs) are intrinsically subtle to water molecules, which remains the major challenge that severely limits their applications as fluorescent probes in aqueous samples. Herein novel composite fluorescent probes were prepared by growing Ln-MOFs (Tb-MOF, Eu-MOF, and Tb/Eu-MOF) on carboxylated porous graphene oxide (PGO-COOH). The 3D thorny composites presented significantly longer fluorescent lifetimes and higher quantum yields than that of the bare Ln-MOFs and exhibited long-term PL stabilities in aqueous samples up to 15 days. The stable and improved PL properties demonstrated that the highly hybrid composite structures protected the MOF components from the adverse effects of water. Furthermore, the unexpected antenna effect of the PGO-COOH substrate on Ln3+ was supposed to be another reason for the improved PL properties. The composites present ultralow detection limits as low as 5.6 nM for 2,4-dinitrotoluene and 2.3 nM for dipicolinic acid as turn-off and ratiometric fluorescent probes, respectively, which was attributed to the incoporation of PGO-COOH that dramatically enahnced inner filter effects and effectively protected the energy transfer process in the MOF components from the interference of the surrounding water. This work presents an effective strategy for creating ultrasensitive and stable fluorescent probes based on Ln-MOFs for applications in aqueous samples.

Diffusion of the analytes across the diffusion boundary layers and subsequently through the fiber coatings determines the extraction kinetics of solid-phase microextraction in aqueous matrices. Besides, the matrix effects can distort the behaviors of the analytes transferring across the diffusion boundary layers. However, these processes were always studied via certain simplification, which often left the mass transfer through the fiber coatings unconsidered and the matrix effects partially investigated. Herein, a comprehensive study on the mass transfer processes in direct immersion solid-phase microextraction was presented. Under different agitation speeds, it was determined that the mass transfer coefficients across the diffusion boundary layers were three to six orders larger than those through the fiber coatings. However, the mass transfer across the diffusion boundary layers was generally the major rate-limiting step. In addition, the shuttle effect and the barrier effect, which were responsible for accelerating and retarding the extraction kinetics, respectively, were found to be the dominant matrix effect alternately under different agitation speeds. This study comprehensively illustrated the major rate-limiting step and the dominant matrix effects through recording the mass transfer coefficients.

The process of oil exploitation is often accompanied by the generation of the corrosive gases, metal particles and minerals, which results in very serious corrosion and wear of petroleum machinery and equipment, which can be greatly reduced by modification of the surface properties of the materials. According to the theory of molecular interaction, the friction effect of a rough surface is better than that of a smooth surface, while fabrication of surfaces with appropriate roughness may reduce the friction. We present the construction of a grooved texture on the surface of 35CrMo using a nano-pulse laser. We found that some micro-/nano-structures were created on the surface, and that a superhydrophobic surface with a water contact angle of 156° and a sliding angle of less than 10° was obtained. Groove textures of different depths produced by using various laser energy densities, the friction coefficient of the superhydrophobic samples was significantly reduced from 0.55 to 0.28 after laser surface texturing under water lubrication conditions. This shows the improvement of the tribological properties.

A series of cathodes with MnO2 catalysts of metal fuel battery were prepared. The catalyst slurry was treated by ultrasonic dispersion under the ultrasonic time of 20 min, 40 min and 60 min. The cathodes were also dried with the temperature of 90°C, 120°C and 150°C. Besides, the microstructures of the cathodes and discharging performance were investigated. The results indicated that the ultrasonic time and drying temperature had a remarkable influence on the electric current densities, but had little effect on the open-circuit voltage. The effects of oxygen on the current density and voltage of cathode were also studied, and it was found that the method of blowing oxygen to cathode could increase the current density of the metal fuel battery.

Single-layer water cut measurement is of great significance for identifying and shutting off the unwanted water, analyzing oil remained and optimizing production. Currently, however, only the water cut of multilayer mixture can be measured by testing samples taken from wellhead, a way which is widely used in oilfields. That of single-layer fluid cannot be determined yet To address the problem, this paper puts forward a new impedance sensor that offers long-term online monitoring of single-layer water cut. This sensor is based on the different electrical conductivity of oil and water. It has two layers. The inner one contains three electrodes - two at both sides sending sinusoidal excitation signals and one at the middle receiving signals that have been attenuated by the water-oil medium. With the Maxwell's model of oil-water mixed fluid, the receiver then can measure the water cut online. The outer layer of the sensor is made of PEEK, an insulative protection. In front of the electrodes lies a static mixer which makes the measurement more accurate by fully blending the two media when they flow through the electrodes. Laboratory tests are carried out with the prototype of the sensor at various oil-water mixing ratios, fluid flow rates, and temperatures. Results show that the average margin of error is within ± 3%. Higher accuracy is seen when high water cut and flow rate enable oil globules to disperse more evenly and the space in between to get wider and the RMS error is less than 2%. If the water cut drops below 80%, the aggregation of the droplets will cause wild fluctuation and more errors in the measurement. In addition, the mineralization of the mixture directly changes its conductivity, which largely impacts the result. Meanwhile, temperature can influence the ionic movement intensity and then alter the conductivity of the medium. Therefore, in practice, the sensor calibration needs to be performed according to the range of medium salinity, and the temperature of the medium is collected in real time for temperature compensation. It is shown that after the adjustment, the water cut measurement results have higher accuracy and consistency. The impedance sensor can realize online water cut monitoring for a single-layer, indicated by tests. It is more suitable for the increasing high water cut oilfields in that it is more accurate as the water cut grows.

International audience; BDD (Boron-doped Diamond) electrode may hold a promising application to detect heavy metal ions for actual water monitoring and early warning, but a poor understanding of influence mechanism of B/C ratio on detection performance is in the way of its fabrication and application. This work is intended to reveal the double-side effect of B/C ratio on detection performance of BDD electrode so as to facilitate its actual application. SBDD (Self-supported Boron-doped Diamond) electrode is introduced for the first time to get rid of the interference factors such as substrate. A systematic investigation is conducted for the influence of B/C ratio on microstructure and electrochemical behavior of SBDD electrodes. With the increase of B/C ratio, the grain size continuously increases, and the preferred orientation gradually changes from plane (220) to (111). The gradual increasing of impurity phase content indicates a deterioration of diamond phase quality. In addition, the electrode electrochemical behavior initially gets better then worse. SBDD electrode with a B/C ratio of 1/500 has the largest active surface area of 2.1 cm2, the smallest diffusion resistance and the highest signal response. Under optimal parameter set, the SBDD electrode enjoys a sensitivity of 0.42 μA L μg−1 cm−2 and a detection limit of 1.12 μg L−1 in a wide linear range of 5–120 ppb. The phase quality and grain morphology jointly contribute to the double-side effect. A suitable B-sp3-C content, preferred orientation of (111) and small particle size may make the performance improvement of BDD electrode available.

This work focuses on improving the repeatability and lifetime of a sensor for the electrochemical detection of trace Pb2+ in seawater. An in-situ graphene modification method was proposed to prepare graphene functionalized self-supported boron-doped diamond (G/SBDD) electrode. A pre-coated copper film on SBDD catalyzed graphene growth through vacuum-annealing at the temperature of 1000 °C. The formation of in-situ graphene was systemically investigated, and a homogeneous bilayer graphene with low defect was in-situ grown on SBDD. Then, the electrochemical behavior of SBDD and G/SBDD for Pb2+ was evaluated in simulated seawater. Compared to SBDD, G/SBDD exhibited a larger active surface area of 0.27 cm2, a higher response signal, and a smaller charge transfer resistance (Rct) of 312 Ω cm−2. Under optimized experimental conditions (a deposition potential of −0.6 V and an accumulation time of 125 s), the G/SBDD electrode achieved a sensitivity of 0.475 μA L μg−1 cm−2 and a detection limit of 0.21 μg L−1 over a wide linear range of 1–100 ppb. Also, the electrode exhibited good reproducibility (RSD value of 2.7%), enhanced stability (96% of the initial response signal after 60 days) and high selectivity. The performance of the designed electrode holds promise for monitoring Pb2+ in seawater.

The secretion disorder of sex hormones is the source that leads to the occurrence of many diseases such as polycystic ovarian syndrome (PCOS), hyperandrogenism and so on. There exist physiological changes in human body when slight fluctuations in concentrations of sex hormones happen. Therefore, it’s of great significance for accurate detection of sex hormones in human body. In this work, TpPa-1 COF solid-phase microextraction (SPME) fiber was prepared using high-efficient in-situ synthesis strategy and coupled with HPLC-MS/MS to detect three sex hormones, including Progesterone (P), testosterone (T) and dehydroepiandrosterone (DHEA) in human serum. The thickness of the coating reached 7 μ m within 2 h. Under the optimal conditions, the established method presented low limit of detections (LODs, ≤ 0.75 ng/mL), wide linear ranges (0.100–100 ng mL−1) and good reproducibility, and three sex hormones (T, P, DHEA) were successfully detected and quantified in human serum. In conclusion, the established SPME method presented high-efficient fiber preparation and good analytical performances of sex hormone detection, therefore was in great potential for application in clinical.

Nanoplastics (NPs) are emerging pollutants which can adsorb large amounts of hydrophobic organic compounds (HOCs) and be ingested by aquatic organisms. NPs interact with dissolved organic matter (DOM) and result in significant impacts on the bioaccumulation of HOCs in the actual environment. For the first time, the joint effects of two complex matrices on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) to Daphnia magna (D. magna) were studied by modeling calculation. The complex matrices, nano-sized polystyrene (PS) and/or humic acid (HA), were under environmentally realistic concentrations. A biodynamic model was modified and the uptake fluxes from all exposure pathways were quantified using the experimental data. A flux estimation showed that the bioaccumulation amounts at equilibrium were mostly dependent on dermal uptake (≥99.3 % of the total). The PS matrix would retard the intestinal uptake process in D. magna, especially for the less hydrophobic PAHs; while the HA or the HA-PS matrix would facilitate the mass transfer of PAHs from the matrix to lipids in the gut. Moreover, the biota matrix accumulation factor (BMAF) were calculated to verify the biodynamic model. This work is helpful to clarify the bioaccumulation effects of PAHs in complex environmental systems.

3D graphene-carbon nanotubes (G-CNTs) composite with unique morphology and structure was prepared by one-step insertion of CNTs into graphene. Subsequently, the G-CNTs composite as a fiber coating material for solid-phase microextraction (SPME) was fabricated on the surface of a stainless steel wire by direct coating method. The prepared coating was tested by the extraction of benzene homologues (BTEX, benzene, toluene, ethylbenzene and m-xylene). Compared with a commercial polydimethylsiloxane (PDMS) fiber, the home-made coating exhibited higher extraction performance for BTEX, and the reasons were discussed systematically. Under the optimized conditions, the prepared coating coupled with chromatography-mass spectrometry (GC–MS) for the analysis of BTEX exhibited wide linear ranges, low limits of detection (3 S/N) (LODs, 0.59–2.68 ng L−1), low limits of quantification (10 S/N) (LOQs, 1.96–8.92 ng L−1), good repeatability (3.2–5.5%, n = 6) and reproducibility (3.7–9.1%, n = 3). Finally, the developed method was successfully applied to the analysis of BTEX in environmental water samples with satisfactory recoveries (84.7–108.1%). This study is expected to further the exploration of high-performance SPME coating materials, and broaden the applications of graphene-based materials.

Wettability is an important characteristic of solid surfaces. Enhancing the surface wettability is very important for improving the properties of materials. Superhydrophobic materials show good prospects for development in areas such as self-cleaning, anti-fog snow, anti-icing, and corrosion resistance. It has become a hot spot to develop a superhydrophobic surface with low surface free energy and good anti-adhesion properties. In this paper, nanosecond pulsed lasers were used to texture the nickel surface, and the different texturing speeds were changed. Combined with the ultrasonic treatment of low surface energy materials, nickel surfaces with different contact angles were obtained. The experimental results show that low surface energy substances can increase the contact angle of nickel surface but the extent of increase is limited. Laser microstructure induces micro & nanostructures. Ultrasonic action can adsorb certain low surface energy substances on the surface, greatly improving the hydrophobic properties of the surface, the contact angle with water up to 152? and the roll angle is less than 2?, and with the increase of the laser texturing speed, the contact angle of the nickel surface shows a decreasing trend.

In this contribution, it was discovered that even distribution of a metal-organic framework (MOF) [e.g. copper 1,4-benzenedicarboxylate (CBDC)] within polymeric matrixes (e.g. polyimide) resulted in a high-efficient coating material on the surface of a stainless steel wire (SSW). Consequently, a home-made solid phase microextraction (SPME) fiber was fabricated for fast determination of target analytes in real water samples. Scanning electron microscope images indicated that the coating possessed homogenously porous surface. Coupled with gas chromatography-mass spectrometry (GC-MS) and direct immersion SPME (DI-SPME) technique, the fiber was evaluated through the analysis of five polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Under optimized extraction and desorption conditions, the established method based on the home-made fiber exhibited good repeatability (4.2–12.7%, n = 6) and reproducibility (0.9–11.7%, n = 3), low limits of detection (LODs, 0.11–2.10 ng L−1), low limits of quantification (LOQs, 0.36–6.99 ng L−1) and wide linear ranges (20–5000 ng L−1). Eventually, the method was proven applicable in the determination of PAHs in real samples, as the recoveries were in a satisfactory range (81.7–116%).

A new enhanced thermo-actuated shape memory polymer (SMP) composite PE-NBR was developed and its properties were compared with traditional SMPs. The numerical simulation and experiment study on packer element were performed by the way of newly developed constitutive model. The functional composite system with shape memory effect is mainly composed of polyolefin acting as shape memory component and particle-filled elastomer acting as modified enhancement component. The PE-NBR system has advantages over traditional SMP with tensile strength of 14.3 MPa, hardness of 71 and shape recovery ratio of 95%. The ratio of polyolefin in the system can be adjusted from 20% to 90% and that of elastomer can be adjusted from 10% to 70%. The constitutive model with rubber plastic blending for PE-NBR system based upon mesomechanics and macroscopic properties of materials is used to meet the numerical study requirements of large-deformation, temperature-dependence and nonlinear composites. The rating pressure of packer element using PE-NBR system is more than 10 MPa and the maximum of contact pressure is obtained in the location which is 60 mm away from the end surface of the element. Key words: shape memory polymer, composite material, mesomechanics, constitutive model, polyolefin, elastomer, packer

Plunger pumps are widely used in oil pumping units around the world. The water content of the wellbore is increasing along with the development progress, so the lubricating capacity of the well fluids between the plunger and barrel is decreasing correspondingly. Commonly, the substrate material of the plunger and barrel are stainless steel, and the plunger surface is usually covered with nickel-based coating. Therefore, the performance of the plunger and barrel has been affected due to poor lubrication and eccentric wear. Non-smooth surfaces have been proven to improve the tribology performance in many cases. A surface texturing plunger covered with specific dimples has been prepared by using laser surface texturing technology. The morphology of the surface texturing plunger was characterized and analyzed. The tribology performance of surface texturing plunger samples was tested using standard friction and wear test machines with oil and water lubrication, respectively. The results indicated that surface texturing could effectively reduce the coefficient of friction, and the wear resistance of the surface textured samples has been improved to some extent.

Herein, through a facile and energy-friendly approach, thermally stable manganese-derived amorphous stacked nanosheet (MASNS) coatings with controlled wetting property ranging from superhydrophilicity to superhydrophobicity were synthesized. The superhydrophobic MASNS coating exhibited remarkable selectivity and sensitivity in the solid phase microextraction (SPME) of non-polar aromatic analytes, even amid the abundance of polar compounds, due to the superhydrophobic effect and the stacked lamellar structures. The established method was applied to the determination of polycyclic aromatic hydrocarbons (PAHs), featuring low LODs (i.e., 0.14–0.24 ng L−1) and wide linear ranges (e.g., 10–10000 ng L−1). Extraction and desorption conditions were optimized to unleash the potential of the fiber before it was applied to the analysis of target analytes in real water samples, where satisfactory recoveries were obtained (81.7%–114.2%). This work might provide critical insights for the scalable production of superhydrophobic nanosheets as affordable and high-performance adsorbents.

Herein, a novel solid-phase microextraction (SPME)fiber based on hollow carbon nanobubbles was developed for the analysis of persistent organic pollutants. The hollow carbon nanobubbles (HCNBs), derived from the nanoscale zeoliticimidazolate framework (ZIF-8), not only possessed the ZIF-8-like microporous shell but also created an internal space for analytes storage. This architecture was beneficial to accelerating the mass transfer process and enhancing the enrichment capacity towards target analytes. As a result, the sensitivity of this HCNBs based SPME fiber toward analytes (e.g., BTEX, PAHs and PCBs) was 2–180 times higher compared with the commercial fibers (100 μm PDMS, 65 μm PDMS/DVB or 85 μm PA). In addition, owing to the size-selectivity of the microporous shell, the HCNBs-based SPME fiber showed high extraction ability towards target analytes with low molecule weight. Furthermore, the lifespan of the homemade fiber was evaluated to be more than 100 times attributing to the hard and stable carbon framework. Under optimal working conditions, analytical performance of the fiber towards PCBs with varying chlorination degrees showed a wide linear range (0.05–1000 ng L−1) and low LODs (0.0017–0.0042 ng L−1). Finally, the established method was successfully applied to the determinations of PCBs in three environmental water samples with good recoveries (84.5–117.1%).

Herein, an intriguing strategy is presented for preparing monolithic metal–organic framework (MOF) coatings through compactly filling up the interparticle spaces in the stacked architectures of nanocrystals. The monolithic coatings exhibited remarkably enhanced performance (double to triple compared to the MOF powders) for analyte extraction, due to the increased volumetric BET areas.

It has been reported that microplastics (MPs) have strong affinity for hydrophobic organic chemicals (HOCs) and can be ingested accidentally by aquatic organisms, posing a potential threat to the environment. To date, the sorption data used in modelling to clarify the mechanism were mostly obtained in varied sampling durations and regions from different works, which might cause inevitable deviation in modelling results. The current study aimed to illustrate the sorption properties of HOCs to the micro-sized polystyrene (PS). The sorption behaviors of HOCs to the PS were investigated at a certain pre-equilibrium status, and the theoretical analysis was taken into consideration. A bottle-shaped passive dosing system was designed to measure the concentration ratio of HOCs in different phases of the exposure suspension at a certain time (logaMP), including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) with logKow ranging from 3.17 to 10.20, between water and PS MPs with different dimensions (diameters of 100 nm, 1 μm and 2 μm, respectively). The calculated logaMP ranged from 3.73 to 8.34, and a positive correlation was found between logaMP and log1r0 (r0 is the MP radius). The results indicated that HOCs would diffuse into the PS particles, but the mass transfers inside the particles were slow and would be negligible in some environmental cases. Under theoretical considerations, the diffusion through the boundary layer of the particle was considered as the dominating process because it was fast, and the contributions of absorbed amounts on the particle surface were larger for smaller PS particles (i.e. 100-nm PS). This study could provide applicable data for further exploring the effects of micro-sized plastics on the HOCs in environmental samples.

Nanoplastics (NPs) spread widely with water and air current, and they can accumulate in aquatic organisms, even penetrating biofilms, which may cause persistent toxicity and potential hazards. This current study aimed to reveal the toxicological mechanism of different functionalized polystyrene (PS) NPs on Daphnia magna (D. magna) by investigating toxicity endpoints in individual level and biochemical level. In this study, acute toxicity, behavioral parameters and biomarker responses of D. magna was measured in the exposure of different functionalized PS NPs (plain PS, PS-p-NH2, PS-n-NH2 and PS-COOH). The results indicated that when exposed to the plain PS, ROS induction would activate MAPKs, thereby causing lethality and adverse behavior effects on D. magna; while the functionalized PS NPs were less toxic than the plain PS, especially for PS-p-NH2 which was severely flocculated after exposure, thus showing no immobilization at the investigated concentrations. Also, the antioxidant system was mainly stimulated due to the direct interaction with the cell surface receptor, which was different from the plain PS. Consequently, this work suggests significant effects of functional groups on NPs for environmental toxicity studies, and provides a better understanding of the toxicological mechanism on the toxicity of PS NPs toward D. magna.

Solar-powered photocatalytic H2O2 production via simultaneous oxygen reduction and water oxidation under ambient conditions is intriguing but challenging to achieve both high oxygen reduction and water oxidation efficiencies. Herein, we report an elaborately modified carbon nitride photocatalyst presenting the highest catalytic efficiency (as high as 75 μM h-1) ever reported in ambient conditions without using any additives. The high oxygen reduction efficiency is achieved owing to the promoted adsorption and direct reduction of O2 on the defective sites of the catalyst, and the storage of electrons in redox molecules as a stable and selective medium for the relayed reduction of O2. Meanwhile, the photo-induced holes exhibit high oxidation potential (1.87 V vs NHE) capable of transforming water into H2O2 selectively, and even degrading organic pollutants as well. This work presents a potent example of producing H2O2 in a real sustainable and economical way.

Solid-phase microextraction (SPME) kinetics in semisolid samples should be different from that in aqueous and gaseous samples, as convection is negligible in semisolid samples but dominates mass transfer in bulk phases of aqueous and gaseous samples. This study developed a mathematical model for describing SPME kinetics in semisolid samples by considering the diffusion of analytes in two compartments, i.e., the fiber coating and the ever-increasing diffusion domain in the sample matrix. The mathematical model predicted that SPME and the desorption of preloaded analytes from the fiber would be isotropic in semisolid samples, while SPME in semisolid samples would not follow the first order kinetics as in aqueous and gaseous samples. The predictions were proven true in the experiment of four pharmaceuticals in agarose gel. In return, it was observed in the experiment that SPME kinetics would deviate more significantly from the first order kinetics for the analytes with higher partition coefficients between t...

To improve wear resistance of expansion cone and decrease the friction between cone and tube, an expansion cone covered by hard coating was prepared and applied in the field. The carbide-based hard coatings were fabricated on the expansion cone surface by using high-velocity oxygen fuel thermal spraying technology, and the coating improved surface hardness of the cone by nearly 60%. The wear tests indicate that: the hard coating reduces friction coefficient of expansion cone sample by over 30% and wear loss by 33% with lithium grease lubricating; the hard coating reduces friction coefficient of expansion cone sample by about 25% with water lubricating; the hard coating reduces the wear and friction between expansion cone and tube significantly, and extends the cone life. Field tests indicate that: the expansion cones with hard coating have excellent wear resistance; the coating bound well with the expansion cone substrate after application for four wells, and no evident abrasion happens on the cone surface; the cone is successfully applied in the field to repair the damaged casings. Key words: expansion cone, expansion tube, hard coating, anti-friction property, wear resistance

Carbohydrates are known to be involved in a wide range of biological and pathological processes. However, due to the presence of multiple hydroxyl groups, carbohydrate recognition is a particular challenge. Herein, we reported an ultrasensitive solid-phase microextraction (SPME) probe based on phenylboronic acid (PBA) functionalized carbon nanotubes (CNTs) for direct in vitro or in vivo recognition of carbohydrates in biofluids as well as semi-solid biotissues. The coating of the proposed probe possessed a 3D interconnected porous architecture formed by the stacking of CNTs. As a result, the binding capacity toward carbohydrates was excellent. The proposed approach was demonstrated to be much superior to most carbohydrate sensors, including higher sensitivity, wider linear range, and excellent qualitative ability in multi-carbohydrate systems. Thus, this approach opens up new avenues for the facile and efficient recognition of carbohydrates for important applications such as glycomics.

Encapsulating functional nanomaterials within the bulk of metal-organic frameworks (MOFs) offers the opportunity to construct high-performance hybrid coating materials for solid phase microextraction (SPME). In this work, we proposed the facile synthesis of a superhydrophobic MOF composite material (NSZIF-8Si) by growing ZIF-8 on MnxOy nanosheet (NS) and subsequently depositing short-chain polysiloxane on the surface of the composite. A novel SPME fiber was successfully prepared based on the NSZIF-8Si composite. The NSZIF-8Si fiber possessed outstanding thermal stability (up to 450 °C). In headspace SPME of BTEX, the home-made fiber exhibited extraction efficiencies much higher than the commercially available PDMS fiber. This phenomenon was due to the synergetic cooperation of the π-π stacking and the hydrophobic interactions between the NSZIF-8Si coating and the analyte molecules, as well as the increased aspect ratio of the MOF grown on the nanosheet. The established method achieved wide linearity (5–2000 ng L−1) and low LODs (0.02 ng L−1 to 0.21 ng L−1). Satisfactory recoveries were obtained in the analysis of real water samples collected from the Pearl River, indicative of the good reliability of the established method for real-scenario applications. This work might provide critical insights in constructing novel NS/MOF composite materials for the development of high-performance SPME fiber coatings.

Herein, an amino-acid-boosted biomimetic strategy is reported that enabled the rapid encapsulation, or co-encapsulation, of a broad range of proteins into microporous metal-organic frameworks (MOFs), with an ultrahigh loading efficiency. It relies on the accelerated formation of prenucleation clusters around proteins via a metallothionein-like self-assembly. The encapsulated proteins maintained their native conformations, and the structural confinement within porous MOFs endowed enzymes with excellent bioactivity, even in harsh conditions (e.g. in the presence of proteolytic or chemical agents or at high temperature). Furthermore, owing to the merits of nondestructive and protein surface charge-independent encapsulation, the feasibility of this biomimetic strategy for biostorage, enzyme cascades, and biosensing was also verified. It is believed that this convenient and versatile encapsulation strategy has great promise in the important fields of biomedicine, catalysis, and biosensing.

The dissolvable bridge plug is one of the most important tools for multi-stage hydraulic fracturing in the field of oil/gas development. The plug provides zonal isolation to realize staged stimulation and, after fracturing, the plug is fully dissolved in produced liquids. A bionic surface was introduced to improve the performance of the plug. Surface dimples in the micron dimension were prepared on the dissolvable materials of the plug. The experimental results showed that the surface dimples changed the hydrophilic and hydrophobic properties of the dissolvable materials. The dissolution rate has a great relation with the parameters of the dimples and can be controlled by choosing the dimples&rsquo, parameters to some degree.

Friction is one of the main causes of mechanical component failure and material waste. It is known from the friction theory that changing the roughness of the surface of the material can change the friction property of the material. Laser surface texturing is a good method for constructing a rough surface. In the experiment, the texture of the circular pits with different areal densities was constructed on the nickel surface. The coefficient of friction of the circular pit under the water-lubricated friction condition was kept at about 0.17, while the untreated metal nickel under the same conditions exceeds 0.65. The circular pit texture improves the frictional properties of the nickel surface.

Solid phase microextraction (SPME), a simple, fast and promising sampling technique, has been widely used for complex sample analysis. However, complex matrices could modify the absorption property of coatings as well as the uptake kinetics of analytes, eventually biasing the quantification results. In the current study, we demonstrated the feasibility of a developed calibration method for the analysis of polycyclic aromatic hydrocarbons (PAHs) in complex milk samples. Effects of the complex matrices on the SPME sampling process and the sampling conditions were investigated. Results showed that short exposure time (pre-equilibrium SPME, PE-SPME) could increase the lifetime of coatings, and the complex matrices in milk samples could significantly influence the sampling kinetics of SPME. In addition, the optimized sampling time, temperature and dilution factor for PAHs were 10 min, 85 °C and 20, respectively. The obtained LODs and LOQs of all the PAHs were 0.1-0.8 ng/mL and 1.4-4.7 ng/mL, respectively. Furthermore, the accuracy of the proposed PE-SPME method for milk sampling was validated by the recoveries of the studied compounds in two concentration levels, which ranged from 75% to 110% for all the compounds. Finally, the proposed method was applied to the screening of PAHs in milk samples.

A series of knitting aromatic polymers (KAPs) were successfully synthesized using a simple one-step Friedel-Crafts alkylation of aromatic monomers and were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then, as-synthesized KAPs with large surface areas, unique pore structures and high thermal stability were prepared as solid-phase microextraction (SPME) coatings that exhibited good extraction abilities for a series of benzene compounds (i.e., benzene, toluene, ethylbenzene and m-xylene, which are referred to as BTEX) and polycyclic aromatic hydrocarbons (PAHs). Under the optimized conditions, the methodologies established for the determination of BTEX and PAHs using the KAPs-triPB and KAPs-B coatings, respectively, possessed wide linear ranges, low limits of detection (LODs, 0.10-1.13ngL(-1) for BTEX and 0.05-0.49ngL(-1) for PAHs) and good reproducibility. Finally, the proposed methods were successfully applied to the determination of BTEX and PAHs in environmental water samples, and satisfactory recoveries (93.6-124.2% for BTEX and 77.2-113.3% for PAHs) were achieved. This study provides a benchmark for exploiting novel microporous organic polymers (MOPs) for SPME applications.

A series of carbon nitride (CNx) films were deposited on Si substrates by ion beam-assisted deposition. The CNx films were deposited by ion sputtering of graphite with N ions and they were additionally bombarded by N ions with low energy during deposition. The films were characterized with atomic force microscope, X-ray photoelectron spectroscopy, Raman spectrum and transmission electron microscope. The results indicated that the characteristics of the CNx films are strongly dependent on the bombarding energy. The hardness, elastic modulus and residual stress of the films were systemically investigated. Comparing with non-bombarding CNx film, the CNx films with bombardment of N ions have higher [N]/[C] ratio and sp3/sp2 ratio. Bombardment of N ions with low bombarding energy could increase sp3/sp2 ratio and improve mechanical properties of CNx films, while further increasing bombarding energy has no evident effect on films' properties. The residual stress of the films exhibited similar trend as hardness with the variation of bombarding energy of N ions.

Carbon nitride (CNx) films were synthesized on silicon substrates by ion beam assisted deposition. Effect of bombarding energy of N ions on the properties of the CNx films was studied. Surface morphology and bonding states of the CNx films were characterized by using atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The results revealed that the surface roughness increased and both [N]/[C] and sp 3 /sp 2 carbon ratio decreased with increasing bombarding energy. Nanoindentation test indicated that hardness of the CNx films decreased with increasing bombarding energy. Surface free energy of the CNx films was calculated based on the results of contact angle measurement. Values of the surface free energy exhibited slight difference for different CNx films.

In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp2 carbon dominated structures, and diversiform bonds (N C, N C, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp2C rich structure of the CNx film as well as its protection function for the archwire was responsible for the low friction of the wire-bracket sliding system.