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The trend of digitalization has produced rapidly increasing data interaction and authentication demand in today's internet of things ecosystem. To face the challenge, we demonstrated a micro-scale label by direct laser writing to perform as a passport between the physical and digital worlds. On this label, the user information is encrypted into three-dimensional geometric structures by a tensor network and then authenticated through the decryption system based on computer vision. A two-step printing methodology is applied to code the randomly distributed fluorescence from doped quantum dots, which achieved physical unclonable functions (PUFs) of the passport. The 10

Conventional flow-based two-phase upscaling for simulating the waterflooding process requires the calculations of upscaled two-phase parameters for each coarse interface or block. The whole procedure can be greatly time-consuming especially for large-scale reservoir models. To address this problem, flow-based two-phase upscaling techniques are combined with machine learning algorithms, in which the flow-based two-phase upscaling is needed only for a small fraction of coarse interfaces (or blocks), while the upscaled two-phase parameters for the rest of the coarse interfaces (or blocks) are directly provided by the machine learning algorithms instead of performing upscaling computation on each coarse interfaces (or blocks). The new two-phase upscaling workflow was tested for generic (left to right) flow problems using a 2D large-scale model. We observed similar accuracy for results using the machine learning assisted workflow compared with the results using full flow-based upscaling. And significant speedup (nearly 70) is achieved. The workflow developed in this work is one of the pioneering work in combining machine learning algorithm with the time-consuming flow-based two-phase upscaling method. It is a valuable addition to the existing multiscale techniques for subsurface flow simulation.

Background Previous studies have demonstrated that interferon (IFN) signaling is enhanced in patients with poor collateral circulation (CC). However, the role and mechanisms of IFN‐alpha in the development of CC remain unknown. Methods We studied the serum levels of IFN‐alpha and coronary CC in a case–control study using logistics regression, including 114 coronary chronic total occlusion (CTO) patients with good coronary CC and 94 CTO patients with poor coronary CC. Restricted cubic splines was used to flexibly model the association of the levels of IFN‐alpha with the incidence of good CC perfusion restoration after systemic treatment with IFN‐alpha was assessed in a mice hind‐limb ischemia model. Results Compared with the first IFN‐alpha tertile, the risk of poor CC was higher in the third IFN‐alpha tertile (OR: 4.79, 95% CI: 2.22–10.4, p

The gas–liquid–solid phase transition of hydrates is complex and has effects that are coupled with the heat-mass transfer in reservoirs; thus, this phase transition is related to the determination of flow assurance and production efficiency. The microfluidic technology applied in this research can simulate a porous medium and is an alternative to the conventional sand-packing approach, encompassing real characteristics of interfaces between multiple phases, reducing the randomness of pore shape, and mastering the distribution of flow channels. The hydrate phase transition was observed directly, while the relationship between the hydrate saturation and the permeability was analyzed. The entire experimental cycle was greatly shortened and was performed at lower cost and with more convenient operation than traditional sand-packing methods. The results indicate that hydrate saturation is negatively correlated with permeability. Considering the properties of etched throats, the newly generated particles can re...

With the wide application of two-photon technology in biological field, lipid-water amphiphilic chromophores containing a large conjugation structure are required. In this study, six polyethylene glycol (PEG) modified benzylidene cycloalkanone photosensitizers (PSs) were selected as models to investigate the effect of their aggregation behaviors on their photophysical properties in deionized water. The results showed that all of these PSs could form aggregates at a suitable concentration in aqueous solution. However, the aggregation behaviors of symmetrically modified PSs (B2, X2 and M2) and asymmetrically modified ones (B3, X3 and M3) were quite different, which had significant effects on their photophysical properties, especially for two-photon excited fluorescence (2PEF). Under a high concentration (2×10−4 M), the compact aggregates of B3 and X3 exhibited enhanced 2PEF intensity versus fluorescence quenching of others. Moreover, B2, X2 and M2 presented higher polarity and lower cytotoxicity, while B2 and B3 with shorter PEG showed good performance in two-photon polymerization, indicating B2 will be a potential PS for 3D microfabrication of biosafety materials.

Molecular photoswitches that can reversibly change color upon irradiation are promising materials for applications in molecular actuation and photoresponsive materials. However, the fabrication of photochromic devices is limited to conventional approaches such as mold casting and spin-coating, which cannot fabricate complex structures. Reported here is the first photoresist for direct laser writing of photochromic 3D micro-objects via two-photon polymerization. The integration of photochromism into thiol-ene photo-clickable resins enables rapid two-photon laser processing of highly complex microstructures and facile postmodification using a series of donor-acceptor Stenhouse adduct (DASA) photoswitches with different excitation wavelengths. The versatility of thiol-ene photo-click reactions allows fine-tuning of the network structure and physical properties as well as the type and concentration of DASA. When exposed to visible light, these microstructures exhibit excellent photoresponsiveness and undergo reversible color-changing via photoisomerization. It is demonstrated that the fluorescence variations of DASAs can be used as a reporter of photoswitching and thermal recovery, allowing the reading of DASA-containing sub-micrometric structures in 3D. This work delivers a new approach for custom microfabrication of 3D photochromic objects with molecularly engineered color and responsiveness.

Background The relationship between high‐density lipoprotein cholesterol (HDL‐C) levels and major adverse cardiovascular events (MACEs) in hypertensive patients of different sexes is unclear. Hypothesis Sex differences in the relationship between HDL‐C levels and the risk of MACEs among hypertensive patients. Methods We performed a post‐hoc analysis of data obtained from the Systolic Blood Pressure Intervention Trial (SPRINT) and explored sex‐based differences in the relationship between HDL‐C levels and MACEs among hypertensive patients using Cox proportional hazards regression. Results A total of 9323 hypertensive patients (6016 [64.53%] men and 3307 [35.47%] women) were assessed using SPRINT data. MACEs occurred in 395 (6.57%) men and 166 (5.02%) women after a mean follow‐up of 3.26 years. When HDL‐C levels were used as a continuous covariate, each 10 mg/dl increase in HDL‐C levels decreased the risk of MACEs in men (hazard ratio [HR], 0.78; 95% confidence interval [CI], 0.70–0.88; p

Background: Women had worse outcomes after acute myocardial infarction (AMI), and physiologically, women had lower hemoglobin values. We examined whether there were sex-related differences in the relationship between hemoglobin levels and adverse outcomes in patients with acute myocardial infarction.Method: We conducted a post-hoc analysis of data from the Acute Coronary Syndrome Quality Improvement in Kerala (ACS-QUIK) Study. We explored the relationship between baseline hemoglobin level and 30-days adverse outcomes by logistic regression model, generalized additive model (GAM) and two-piecewise linear regression model. We used multiple imputation, based on five replications and a chained equation approach method in the R multiple imputation procedure, to account for missing data. The primary outcome were 30-day major adverse cardiovascular events (MACEs) defined as death, reinfarction, stroke, and major bleeding. The secondary outcomes were 30-day major bleeding, 30-day stroke and 30-day cardiovascular death (CVD death).Results: Twenty thousand, five hundred fifty-nine patients with AMI were included in our analysis. Baseline hemoglobin level was associated with major bleeding [OR: 0.74, 95%CI (0.60, 0.92) P < 0.01], CVD death [OR: 0.94, 95%CI (0.90, 0.99) P < 0.01], and MACEs [OR: 0.95, 95%CI (0.92, 0.99) P < 0.01]. There was no significant relationship between baseline hemoglobin level and stroke incidence in both men [OR: 1.02, 95%CI (0.90, 1.14) P = 0.77] and women [OR: 1.15, 95%CI (0.96, 1.37) P = 0.18]. Baseline hemoglobin level was associated with major bleeding [OR: 0.71, 95%CI (0.58, 0.85) P < 0.01] in male patients, however we did not find the same relationship in female patients [OR: 0.89, 95%CI (0.56, 1.41) P = 0.61]. GAM and two-piecewise linear regression model showed the relationships of hemoglobin level with major bleeding, CVD death, and MACEs were non-linear (non-linear P < 0.05), and the threshold value were 13, 14.8, and 14.3 g/dL for MACEs and CVD death, respectively.Conclusion: Baseline hemoglobin level was one of the independent predictors of prognosis in South Asia patients with acute myocardial infarction. Moreover, its impact on prognosis was largely different depending on the patients' sex.

A new class of photoresist is described for direct laser writing of photoswitchable 3D microstructures. The material comprising off-stoichiometric thiol-ene photo-clickable resins enables rapid two-photon laser processing of highly complex structures and facile post-modification with photoswitches. The microstructures were functionalized with a series of donor-acceptor Stenhouse adducts (DASAs) photoswitches with different excitation wavelength. The versatility of thiol–ene photo-click reaction enabled fine-tuning of the network structure and physical properties as well as the type and concentration of DASA photoswitches. When exposed to visible light, these microstructures exhibit excellent photo-responsiveness and undergo reversible color-changing via photoisomerization of DASA moieties. We describe that the weak fluorescence of DASAs can be used as a reporter of photoswitching, color changes, and thermal recovery, allowing the reading of DASA-containing sub-micrometric structures in 3D. This work delivers a new approach for custom microfabrication of 3D photochromic objects with molecularly engineered color and responsiveness.

Microrobots and metal–organic frameworks (MOFs) have been identified as promising carriers for drug delivery applications. While clinical applications of microrobots are limited by their low drug loading efficiencies and the poor degradability of the materials used for their fabrication, MOFs lack motility and targeted drug delivery capabilities. The combination of these two fields marks the beginning of a new era; MOF‐based small‐scale robots (MOFBOTs) for biomedical applications. Yet, biodegradability is a major hurdle in the field of micro‐ and nanoswimmers including small‐scale robots. Here, a highly integrated MOFBOT that is able to realize magnetic locomotion, drug delivery, and selective degradation in cell cultures is reported for the first time. The MOF used in the investigations does not only allow a superior loading of chemotherapeutic drugs and their controlled release via a pH‐responsive degradation but it also enables the controlled locomotion of enzymatically biodegradable gelatin‐based helical microrobots under magnetic fields. The degradation of the integrated MOFBOT is observed after two weeks, when all its components fully degrade. Additionally, drug delivery studies performed in cancer cell cultures show reduced viability upon delivery of Doxorubicin within short time frames. This MOFBOT system opens new avenues for highly integrated fully biodegradable small‐scale robots., Advanced Healthcare Materials, 9 (20), ISSN:2192-2640, ISSN:2192-2659

Wireless micro- and nanorobots are biomedical devices with a potential use in high-precision minimally invasive therapies. Here, a highly integrated multifunctional soft microrobot is developed for targeted cell therapy applications, featuring targeted cell transportation and induced cell differentiation. The micromachines are made of composites consisting of a soft piezoelectric polymer matrix in which magnetic nanoparticles are dispersed. The magnetic nanoparticles serve as the component for the device's magnetic actuation, while the piezoelectric polymer acts as both a steerable scaffold and an acoustically responsive cell electrostimulation platform. With the application of a rotating magnetic field, the microrobots swim in a corkscrew motion in different liquid environments that mimic human body fluids. When the swimmers are subjected to acoustic waves, their piezoelectric body is electrically polarized which induces cell differentiation of neuron-like PC12 cells loaded on the swimmers surface. This combinatorial technique may open up new avenues for bioelectronic therapies., Materials Horizons, 6 (7)

Increasing accumulation of highly persistent and non-biodegradable organic pollutants in our fresh water sources imposes a threat to human health. Designing novel catalytic materials that can efficiently harness energy from their surroundings to degrade such problematic pollutants is essential. In this work, we fabricated core–shell microhelical robots composed of iron oxide@titanium dioxide (Fe3O4@TiO2) for UV-visible light driven degradation of organic pollutants in a cost-effective manner. Bio-templating and sol–gel synthesis were employed for a simplified approach to batch-fabricate magnetic photocatalysts. These hybrid microrobots removed 97% of RhB dye from contaminated water in 75 minutes using UV-visible light (k-value of 0.047 min−1). Furthermore, when photocatalytic degradation was performed under continuous magnetic field driven propulsion, 99% of RhB dye degraded in 40 minutes with a k-value of 0.108 min−1. We also observed a strong correlation between the hybrid microhelices' swimming characteristics and their subsequent photocatalytic degradation efficiency. These results were further corroborated using COMSOL simulations., Journal of Materials Chemistry A, 7 (43), ISSN:2050-7488, ISSN:2050-7496

Hydrocarbon recovery and reserves estimation largely depend upon the hydrocarbon-water-mineral wettability. However, wettability is a complex parameter and experimental measurements are still open to large uncertainty. We thus demonstrate here that quartz wettability correlates with the density of the non-aqueous fluid, e.g. oil, CO2, N2, etc. – which can be in a liquid, gaseous or supercritical form. This insight significantly simplifies wettability assessments, thus enhancing fundamental understanding of wettability and the related fluid dynamics in siliciclastic hydrocarbon reservoirs. Furthermore, this observed correlation may promote hydrocarbon recovery and reserves prediction in siliciclastic reservoirs.

Production optimization is an effective technique to maximize the oil recovery or the net present value in reservoir development. Recently, the stochastic simplex approximation gradient (StoSAG) optimization algorithm draws significant attention in the optimization algorithm family. It shows high searching quality in large-scale engineering problems. However, its optimization performance and features are not fully understood. This study evaluated and analyzed the influence of some key parameters related to the optimization process of StoSAG including the ensemble size to estimate the approximation gradient, the search step size, the cut number, the perturbation step size, and the initial position by using 47 mathematical benchmark functions. Statistical analysis was employed to diminish the randomness of the algorithm. The quality of the optimization results, the convergence, and the computational time consuming were analyzed and compared. The parameter selection strategy was presented. The results showed that a larger ensemble size was not always favorable to obtain better optimization results. The increase of the search step size was favorable to escape from the local optimum. A large step size needed to match a large cut number. The increase of cut number was beneficial to increase the local searchability, but also made the algorithm more easily fall into the local optimum. The random initial position was beneficial to find the global optimal point. Moreover, the effectiveness of the parameter selection strategy was tested by a classical reservoir production optimization example. The final net present value (NPV) for water flooding reservoir production optimization substantially increased, which indicated the excellent performance of StoSAG by adjusting the key parameters.

The apelin/apelin receptor (ApelinR) signal transduction pathway exerts essential biological roles, particularly in the cardiovascular system. Disturbances in the apelin/ApelinR axis are linked to vascular, heart, kidney, and metabolic disorders. Therefore, the apelinergic system has surfaced as a critical therapeutic strategy for cardiovascular diseases (including pulmonary arterial hypertension), kidney disease, insulin resistance, hyponatremia, preeclampsia, and erectile dysfunction. However, apelin peptides are susceptible to rapid degradation through endogenous peptidases, limiting their use as therapeutic tools and translational potential. These proteases include angiotensin converting enzyme 2, neutral endopeptidase, and kallikrein thereby linking the apelin pathway with other peptide systems. In this context, apelin analogs with enhanced proteolytic stability and synthetic ApelinR agonists emerged as promising pharmacological alternatives. In this review, we focus on discussing the putative roles of the apelin pathway in various physiological systems from function to dysfunction, and emphasizing the therapeutic potential of newly generated metabolically stable apelin analogs and non-peptide ApelinR agonists.

Gas productivity of current hydrate reservoir tests is too lower to meet the demand of the commercial level. The main reasons include the low permeability of hydrate-bearing layer (HBL) and the existence of permeable burdens in natural gas hydrate reservoir, which act as the major barriers for pressure drop propagation during depressurization. However, previous studies are focusing on either permeable burdens or hydraulic fracturing. This paper proposed a novel modified method of depressurization by hydraulic fracturing assisted with sealing burdens. The effects of the radial length and permeability of fractured domain, and the sealing location and length of overburden and underburden layers on hydrate dissociation and gas production were analyzed through numerical simulation. The results indicated:1) The larger permeability and longer radial length of the fracturing domain would promote propagation of pressure drop significantly, and the percentage of gas hydrate dissociation would be increased from 3.99% to 29.86% by hydraulic fracturing. 2) The sealing length of burdens should be larger than the fracturing radial length. The cumulative gas production could be enhanced by 93.25% while the cumulative water production could be decreased by 62.99% compared with no sealing burdens. Base on the novel method, the goals of enhancing gas production and reducing water production would be achieved simultaneously, providing important implications for hydrate commercial exploitation in the future.

Ascorbic acid (AA) infusion and modulated electrohyperthermia (mEHT) are widely used by integrative cancer practitioners for many years. However, there are no safety and pharmacokinetics data in Chinese cancer patients. We carried out a clinical trial to evaluate the safety and pharmacokinetics of those methods in patients with stage III-IV non-small cell lung cancer (NSCLC). Blood ascorbic acid in the fasting state was obtained from 35 NSCLC patients; selecting from them 15 patients with stage III-IV entered the phase I study. They were randomized allocated into 3 groups, and received doses 1.0, 1.2, 1.5 g/kg AA infusions. Participants in the first group received intravenous AA (IVAA) when mEHT was finished, in the second group IVAA was administered simultaneously with mEHT and in the third group IVAA was applied first, and followed with mEHT. Pharmacokinetic profiles were obtained when they received solely IVAA and when IVAA in combination with mEHT. The process was applied 3 times a week (every other day, weekend days off) for 4 weeks. We found that fasting plasma AA levels were significantly correlated with stage of the disease. Peak concentration of AA was significantly higher in the simultaneous treatments than in other combinations with mEHT or in solely IVAA-managed groups. IVAA synergy with simultaneous mEHT is safe and the concomitant application significantly increases the plasma AA level for NSCLC patients.

The swelling behaviors of Na-montmorillonite (Na-Mt) in non-ambient environment have been the subject of considerable speculation due to the difficulties associated with their study. Inorganic salts are often used to minimize clay mineral hydration. The influence of inorganic salts addition (NaCl, CaCl 2 , KCl) on the hydration of Na-Mt at high temperature and high pressure (HTHP) was investigated by molecular dynamics simulation at 6 GPa and different temperatures (200, 300, 400, 500 and 600 K) in an isobaric isothermal ensemble (NPT). Water model and force field used in the clay-water system are SPC/E model and universal force field (UFF), respectively. The results show that after adding inorganic salts into Na-Mt, the mobility of the interlayer species increases, and the hydration shell of the interlayer cations decreases with a rise in temperature. The influence of temperature on the diffusion of water molecules is much greater than that of the ions present in the interlayer. Temperature increase and hydration degree play an important role on the diffusion behavior of the interlayer species. The size, valence, mass and hydration energy of cations present between the layers affect the structure of Na-Mt interlayer. The inorganic salts are able to inhibit the hydration of Na-Mt by reducing the mobility of the interlayer species and the basal spacing. After analyzing the effect of each salt on Na-Mt, it was found that, the most stable state of Na-Mt at HTHP is achieved with KCl addition, compared with NaCl and CaCl 2 . It is expected the results obtained from this study would help to understand the inhibition effect of inorganic salts on Na-Mt, and predict the swelling of Na-Mt at HTHP.

Gas hydrate is not only a potential energy resource, but also almost the biggest challenge in oil/gas flow assurance. Inorganic salts such as NaCl, KCl and CaCl2 are widely used as the thermodynamic inhibitor to reduce the risk caused by hydrate formation. However, the inhibition mechanism is still unclear. Therefore, molecular dynamic (MD) simulation was performed to study the dissociation of structure I (SI) methane hydrate in existence of inorganic salt aqueous solution on a micro-scale. The simulation results showed that, the dissociation became stagnant due to the presence of liquid film formed by the decomposed water molecules, and more inorganic ions could shorten the stagnation-time. The diffusion coefficients of ions and water molecules were the largest in KCl system. The structures of ion/H2O and H2O/H2O were the most compact in hydrate/NaCl system. The ionic ability to decompose hydrate cells followed the sequence of: Ca2+>2K+>2Cl->2Na+.

A series of water-soluble benzylidene cyclanone dyes T1 - T3 were synthesized. Their photo-physical properties were investigated using UV–Vis spectra, fluorescence spectra and two-photon absorption spectra. The maximum two-photon absorption cross-sections (σ 2 ) of T1 - T3 in deionized water were determined as 567 GM, 808 GM and 231 GM. Using T1 - T3 as photoinitiators (PIs) directly, 2D and 3D nano patterns based on two-photon crosslinking or polymerization of bovine serum albumin (BSA), water-soluble acrylic ester monomer (SR610) and hyaluronic acid derivative (HAGM) were successfully fabricated, respectively. Much lower threshold energies and wider fabrication windows were obtained in the formulations containing these PIs compared with commercial ones. Furthermore, the cytotoxicity study showed a favorable biocompatibility of these PIs, which indicated T1-T3 would have application prospects in 3D fabrication of biomaterials.

The purpose of this study was to develop a safe and non-toxic alternative to the conventional conservative treatment of peritoneal carcinomatosis with malignant ascites (PCMA) by investigating the efficacy and safety of local modulated electro-hyperthermia (mEHT) combined with the traditional Chinese medicine (TCM) ‘Shi Pi’ herbal decoction, compared with standard intraperitoneal chemoinfusion (IPCI). A randomized, controlled, single-center, open-label clinical trial (phase II) with two parallel groups (allocation ratio, 1:1) was conducted to investigate the efficacy and safety of mEHT+TCM (study group, SG) vs. standard IPCI (control group, CG) in patients with PCMA by intention-to-treat analysis. A total of 260 patients with PCMA were randomly allocated into the two groups (130/130); mEHT was applied for 60 min per session every second day for 4 weeks, for a total of 14 sessions. The TCM decoction was administered orally, at 400 ml daily. In CG, occlusive IPCI with cisplatin (30–60 mg) and fluorouracil (500–600 mg/m2) was applied twice, biweekly. The objective response rate (ORR), quality of life (QoL) and adverse event rate (AER) in the two groups were evaluated 1 month after treatment, analyzed and compared. The present study is registered on ClinicalTrials.gov (NCT02638051). No case was lost or excluded (0/260). The ORR in SG was 77.69% (101/130) vs. 63.85% (73/130) in CG (P

Additional file 1: Table S1. The definitions for cardiac death, MI, and stroke. Table S2. Sensitivity analysis.

CO2 enhanced shale gas recovery (CO2-ESGR) draws worldwide attentions in recent years with having significant environmental benefit of CO2 geological storage and economic benefit of shale gas production. This paper is aimed at reviewing the state of experiment and model studies on gas adsorption, competitive adsorption of CO2/CH4, and displacement of CO2-CH4 in shale in the process of CO2-ESGR and pointing out the related challenges and opportunities. Gas adsorption mechanism in shale, influencing factors (organic matter content, kerogen type, thermal maturity, inorganic compositions, moisture, and micro/nano-scale pore), and adsorption models are described in this work. The competitive adsorption mechanisms are qualitatively ascertained by analysis of unique molecular and supercritical properties of CO2 and the interaction of CO2 with shale matrix. Shale matrix shows a stronger affinity with CO2, and thus, adsorption capacity of CO2 is larger than that of CH4 even with the coexistence of CO2-CH4 mixture. Displacement experiments of CO2-CH4 in shale proved that shale gas recovery is enhanced by the competitive adsorption of CO2 to CH4. Although the competitive adsorption mechanism is preliminary revealed, some challenges still exist. Competitive adsorption behavior is not fully understood in the coexistence of CO2 and CH4 components, and more experiment and model studies on adsorption of CO2-CH4 mixtures need to be conducted under field conditions. Coupling of competitive adsorption with displacing flow is key factor for CO2-ESGR but not comprehensively studied. More displacement experiments of CO2-CH4 in shale are required for revealing the mechanism of flow and transport of gas in CO2-ESGR.

Advanced Materials, 31 (27), ISSN:0935-9648, ISSN:1521-4095

Magnetically controlled synthetic and living micropropellers stir up nanoparticles for enhanced drug transport., Nanoparticles (NPs) have emerged as an advantageous drug delivery platform for the treatment of various ailments including cancer and cardiovascular and inflammatory diseases. However, their efficacy in shuttling materials to diseased tissue is hampered by a number of physiological barriers. One hurdle is transport out of the blood vessels, compounded by difficulties in subsequent penetration into the target tissue. Here, we report the use of two distinct micropropellers powered by rotating magnetic fields to increase diffusion-limited NP transport by enhancing local fluid convection. In the first approach, we used a single synthetic magnetic microrobot called an artificial bacterial flagellum (ABF), and in the second approach, we used swarms of magnetotactic bacteria (MTB) to create a directable “living ferrofluid” by exploiting ferrohydrodynamics. Both approaches enhance NP transport in a microfluidic model of blood extravasation and tissue penetration that consists of microchannels bordered by a collagen matrix.

Depressurization is an effective method to exploit natural gas hydrate reservoirs. However, ice might be formed due to the endothermic effect of hydrate dissociation, which will have a significant influence on gas production. In this work, a numerical model is established to investigate the hydrate dissociation performance by depressurization near the quadruple point. The impact of production pressure and intrinsic permeability on gas production and ice formation are also analyzed. It is revealed that the ice tends to be formed around the perforated interval due to the lower production pressure. A decrease in the effective porosity and permeability due to ice formation has been observed. But in fact, the formed ice has played a positive role in enhancing gas production owing to the released latent heat during ice formation. A large amount of ice is formed which results in a higher gas production rate when the production pressure is lower. The gas production rate and ice formation are greatly enhanced in the early production stage of a hydrate reservoir with a relatively high intrinsic permeability. For a hydrate reservoir with low permeability, ice formation is beneficial for gas production in the long term.

In-situ remediation is an important technique for non-aqueous phase liquid (NAPL) contamination remediation in soils. Understanding the formation and distribution of NAPL contaminated layers in heterogeneous soils is essential to propose cost-effective remediation methods. Therefore, a two-dimensional microfluidic device with dual permeability zones was designed to simulate the soil-groundwater system and experimentally investigated the formation process of the NAPL contamination layer. Numerical modeling of phase field coupled with laminar flow was used to simulate the distribution of NAPL in soil-groundwater system, and the formation of NAPL contamination layer under typical groundwater flow rate and wetting angle was evaluated. The NAPL in the low permeable zone formed a stable contamination layer, while the NAPL in the high permeable zone was washed out to varying degrees and mainly resided in the junction of high-low-permeability regions of the chip, with residues of 42.2% and 23.3% in the chip high permeable region at groundwater velocities of 6.17 m/d and 10.16 m/d, respectively, the numerical simulation results were consistent with the experimental observations. This retention was diminished in the high permeable zone as the NAPL-to-wall wetting angle increased. In addition, when the contact angle was increased from 33° (lipophilic) to 108° (hydrophilic), the residual NAPL content in the high permeable zone decreased from 48.86% to 28.22%. This paper provides a reliable visualizable experimental platform for the study of NAPL pollution formation at micro-scale in heterogeneous groundwater system, and lays a foundation for the subsequent optimization of the remediation strategy.

Natural gas hydrate is an unstable clathrate that can transform from solid to gas and liquid, making it difficult to precisely predict the heat and mass transfer in the pores. In this research, a microfluidics technology is introduced to directly monitor the hydrate phase transition processes in different sized throats. A new method for the calculation of hydrate saturation, named geometric measurement, is proposed with the assistance of magnified images, and this method is compared with two traditional methods to verify their applicability by discussing their related error sources. After analysis, the derivation calculation method is believed to have a wider scope of implementation but a larger error due to its numerous assumptions of an ideal state. At the beginning of the experiments, the saturations obtained by geometric measurement are believed to be larger than the actual values due to internal incompletely formation. As the void spaces were gradually eliminated, the geometric measurement results became more accurate. In contrast, the saturations obtained by fluid displacement were initially believed to be accurate, and became larger than the actual values with increasing hydrate growth due to the blockage of the flow throat. The relative errors of the different methods were calculated by selecting the results of fluid displacement before 60% hydrate saturation and the geometric measurement results of the remaining range as the reference standard. The comparison indicated that the accuracies of the geometric measurement and the fluid displacement were similar to and higher than those of the derivation calculation, respectively. In addition, the effects of the error sources were found to be weakened with increasing hydrate saturation and throat inner width.

Advanced Functional Materials, 30 (17), ISSN:1616-3028, ISSN:1616-301X

ACS Nano, 12 (6), ISSN:1936-0851, ISSN:1936-086X

The inhibition properties of kinetic hydrate inhibitor (KHI) molecules on the dynamic growth of a hydrate/water interface are investigated by using molecular dynamics simulations. The shape of the hydrate interface is transformed from laminar to funnel by PVCaps. Results indicate that the inhibition effects not only depend on the adsorption capacity which was believed to determine inhibition, but also on the fact that PVCaps must have some non-binding-hydrate sites that don’t tend to combine with hydrate. By observing the time evolution of the distance between each component of PVCaps and hydrate, the heterocyclic ring of PVCaps mainly contributes to adsorption and can preferentially adjust itself to come into contact with a hydrate semi-large-cage. The distance between the amide of PVCaps and hydrate is about 4 A and exceeds the range of a general hydrogen bond (3.5 A), which proves that the non-binding-hydrate sites of PVCaps exist. On the other hand, the amide of PVCaps is at the intersection of the solid–liquid interface but has no adsorption affinity for hydrate, so this adsorption pattern indicates that the PVCaps at the hydrate interface are not stable. Due to this unstable adsorption, a repeated hydrate destruction phenomenon was revealed by the identification algorithm of hydrate and the calculation of the local number density of methane. The statistical evolution of water rings further proved the existence of non-binding-hydrate sites in PVCaps and the inhibition mechanism to destroy the hydrate cages by PVCaps. This unstable adsorption mechanism may shed light on the development of novel efficient KHIs.

Nonaqueous-phase liquid (NAPL) contaminants are difficult to eliminate from natural aquifers due, in part, to the heterogeneous structure of the soil. Chemotaxis enhances the mixing of bacteria with contaminant sources in low-permeability regions, which may not be readily accessible by advection and dispersion alone. A microfluidic device was designed to mimic heterogeneous features of a contaminated groundwater aquifer. NAPL droplets (toluene) were trapped within a fine pore network, and bacteria were injected through a highly conductive adjacent macrochannel. Chemotactic bacteria (Pseudomonas putida F1) exhibited greater accumulation near the pore network at 0.5 m/day than both the nonchemotactic control and the chemotactic bacteria at a higher groundwater velocity of 5 m/day. Chemotactic bacteria accumulated in the vicinity of NAPL droplets, and the accumulation was 15% greater than a nonchemotactic mutant. Indirect evidence showed that chemotactic bacteria were retained within the contaminated low-permeability region longer than nonchemotactic bacteria at 0.25 m/day. This retention was diminished at 5 m/day. Numerical solutions of the bacterial-transport equations were consistent with the experimental results. Because toluene is degraded by P. putida F1, the accumulation of chemotactic bacteria around NAPL sources is expected to increase contaminant consumption and improve the efficiency of bioremediation.