Performance Investigation of Asphaltene Adsorption at a Carbonate Rock Surface: Spectroscopy Experiment and Molecular Simulation.

Investigation of asphaltene adsorption at rock surfaces plays an important role in enhanced oil recovery (EOR) for the petroleum industry. In this work, the interaction performances of asphaltene adsorption at carbonate dolomite and calcite surfaces are investigated based on experimental and simulation insights. On the one hand, macroscopic interaction performances were investigated by spectroscopy experiments to obtain the Langmuir thermodynamic model and pseudo-second-order (PSO) kinetic model. The results indicated monolayer molecular asphaltene adsorption for both dolomite and calcite, while they showed 'slow adsorption-slow desorption' for dolomite but 'fast adsorption-fast desorption' for calcite. Meanwhile, dolomite showed a higher adsorption capacity with qm(dol 1) = 5.35 mg/g > qm(cal 1) = 1.28 mg/g and a stronger adsorption spontaneity with ΔGm(dol 1)θ = -7.76 kJ/mol < ΔGm(cal 1)θ = -4.76 kJ/mol. On the other hand, microscopic interaction performances were investigated for three asphaltene molecules by molecular dynamics simulation (MDS) with ∼8 Å distance-placing and 500 ps time-running. According to the results, dolomite showed higher system stability than calcite with a lower final energy of ΔEdol-cal = -58 kJ/mol, and archipelago asphaltene showed higher adsorption stability with the smallest equilibrium energy of Earch(dol) = -147 kJ/mol for albite and Earch(cal) = -89 kJ/mol for calcite. The model of molecular orientation and force dominance was proposed as the interaction mechanism for asphaltene adsorption, which "lie sideways" at low concentrations but "stands upright" at high concentrations. This work allows the performance investigation and mechanism illustration of asphaltene adsorption at rock surfaces, which can help gain a fundamental understanding of the EOR during reservoir exploitation.

Insights into Zwitterionic Surfactant Interactions at the Oil-Water Interface by Interferometry Experiments and MDS Calculations.

In this work, the interaction performance of zwitterionic surfactant [dodecyl dimethyl sulfopropyl betaine (DSB-12) and hexadecyl dimethyl sulfopropyl betaine (DSB-16)] at the n-octadecane oil surface is investigated from experimental and simulation insights. For a macroscopic experiment, interfacial interferometry technology was developed for real-time monitor interaction performances and to obtain the quantitative interfacial thickness and mass results. The Langmuir model was characterized by thermodynamic analysis, deducing the aggregation spontaneity of DSB-16 > DSB-12 with ΔGagg(DSB-16) = -5.94 kJ mol-1 < ΔGagg(DSB-12) = 24.08 kJ mol-1. A three-step dynamic model (adsorption, arrangement, and aggregation) was characterized by kinetic analysis, indicating arrangement process as slow-limiting step with k2(arr) < k1(ads), k3(agg). For microscopic simulation, and molecular dynamic (MD) method was utilized to theoretically investigate interaction performances and obtain the interfacial configuration and energy results. The interaction stability and interaction strength were indicated to be DSB-16 > DSB-12 with differences of final energy ΔEfin = 48-88 kcal mol-1. The interaction mechanism was explained by proposing the model of "response enhancement" and "deposition activity" for DSB-16 interactions, and "response decrease" and "elution activity" for DSB-12 interactions. The different performances can be attributed to the different interaction forms and forces of surfactants. This work provided a platform for performance and mechanism investigation between the surfactant molecule and oil surface, which is of great significance in reservoir exploitation and enhanced oil recovery (EOR).

Recent Progress in Gd-Containing Materials for Neutron Shielding Applications: A Review.

With the rising demand for nuclear energy, the storage/transportation of radioactive nuclear by-products are critical safety issues for humans and the environment. These by-products are closely related to various nuclear radiations. In particular, neutron radiation requires specific protection by neutron shielding materials due to its high penetrating ability to cause irradiation damage. Herein, a basic overview of neutron shielding is presented. Since gadolinium (Gd) has the largest thermal neutron capture cross-section among various neutron absorbing elements, it is an ideal neutron absorber for shielding applications. In the last two decades, there have been many newly developed Gd-containing (i.e., inorganic nonmetallic-based, polymer-based, and metallic-based) shielding materials developed to attenuate and absorb the incident neutrons. On this basis, we present a comprehensive review of the design, processing methods, microstructure characteristics, mechanical properties, and neutron shielding performance of these materials in each category. Furthermore, current challenges for the development and application of shielding materials are discussed. Finally, the potential research directions are highlighted in this rapidly developing field.

Modulating Polymer Dynamics via Supramolecular Interaction with Ultrasmall Nanocages for Recyclable Gas Separation Membranes with Intrinsic Microporosity.

The engineering of mixed-matrix membranes is severely hindered by the trade-off between mechanical performance and effective utilization of inorganic fillers' microporosity. Herein, we report a feasible approach for optimal gas separation membranes through the fabrication of coordination nanocages with poly(4-vinylpyridine) (P4VP) via strong supramolecular interactions, enabling the homogeneous dispersion of nanocages in polymer matrixes with long-term structural stability. Meanwhile, suggested from dynamics studies, the strong attraction between P4VP and nanocages slows down polymer dynamics and rigidifies the polymer chains, leading to frustrated packing and lowered densities of the polymer matrix. This effect allows the micropores of nanocages to be accessible to external gas molecules, contributing to the intrinsic microporosity of the nanocomposites and the simultaneous enhancement of permselectivities. The facile strategy for supramolecular synthesis and polymer dynamics attenuation paves avenues to rational design of functional hybrid membranes for gas separation applications.

Unique Dynamics of Hierarchical Constrained Macromolecular Ligands on Coordination Nanocage Surface Promotes Facile and Precise Assembly of Polymers.

With access to the solution structures of nanocomposites of coordination nanocages (CNCs) via scattering and chromatography techniques, their mysterious solution dynamics have been, for the first time, resolved, and interestingly, the surface macromolecules can be substituted by extra free macromolecules in solutions. Obvious exchange of macromolecules can be observed in the solution mixtures of CNC nanocomposites at high temperatures, revising the understanding of the dynamics of CNC nanocomposites. Being distinct from nanocomposites of a simple coordination complex, the quantified solution dynamics of CNC nanocomposites indicates a typical logarithmic time dependence with the dissociation of surface macromolecules as the thermodynamically limiting step, suggesting strongly coupled and hierarchically constrained dynamics among the surface macromolecules. Their dynamics can be activated only upon application of high temperature or selected solvents, and therefore, the rational design of polymer assemblies, for example, hybrid-arm star polymers with precisely controlled compositions and reprocessable, robust CNC-cross-linked supramolecular polymer networks, is facilitated.

Polymer-templated supramolecular co-assemblies of proteins and metal oxide clusters as versatile platform for chemo-enzymatic catalysis.

The hybridization of enzymes and inorganics in controlled manner is challenging, however, critical for the development of chemo-enzymatic cascade catalyst with high efficiency and selectivity. Here, proteins and metal oxide clusters can be facilely co-assembled on the surface of colloid of poly(4-vinylpyridine) (P4VP) via hydrogen bonding, due to their enriched surface hydrogen bonding donors. The co-assembly method can be generally applied for preparing chemo-enzymatic catalyst within the selected database of various proteins and metal oxide clusters while the assembly units retain their structures and activities. Typically, a 2.5 nm metal oxide cluster {Mo72Fe30}, with peroxidase-like activity, are complexed with glucose oxidase (GOX) on P4VP for the catalysis against the oxidization of o-dianisidine (ODA) with the existence of glucose. Due to the synergistic effects of chemical and enzymatic catalysis, the co-assemblies show even higher ODA oxidation activity compared to GOX/catalase bi-enzymatic system, confirming the effectiveness of the co-assembly protocol for cascade catalysis and enabling its applications in rapid glucose detection and biomass conversion.

A Novel Multiagent Neurodynamic Approach to Constrained Distributed Convex Optimization.

This paper considers a class of distributed convex optimization problems with constraints and gives a novel multiagent neurodynamic approach in continuous-time form. The considered distributed optimization is to search for a minimizer of the summation of nonsmooth convex functions on some agents, which have local general constraints. The proposed approach solves the objective function of each agent individually, and the state solutions of all agents reach consensus asymptotically under mild assumptions. In particular, the existence and boundedness of the global state solution to the dynamical system are guaranteed. Moreover, the state solution reaches the feasible region of equivalent optimization problem asymptotically and the output of each agent is convergent to the optimal solution set of the primal distributed problem. In contrast to the existing methods in a distributed manner, the proposed approach is more convenient for general constrained distributed problems and has low structure complexity which could narrow the bandwidth of communication. Finally, the proposed neurodynamic approach is applied to two numerical examples and a class of power system optimal load-sharing problems to support the theoretical results and its efficiency.

Sub-nanoscaled Metal Oxide Cluster-Integrated Polymer Network for Quasi-Homogeneous Catalysis.

The simultaneous improvement of catalytic activity and recyclability of metal oxides is exciting, however challenging, due to the paradox for particle size requirements. Herein, we report the design of polymer nanocomposites (PNCs) by covalently integrating a sub-nanoscaled metal oxide cluster (∼0.7 nm) into a polymer network with superelasticity. Due to the ultrasmall sizes of loaded clusters and the high swelling ratios (SRs) of PNCs, the swelled organogels from PNCs claim similar catalytic efficiencies to homogeneous catalysts, while their recyclability can be simply achieved after the catalytic reactions. Thanks to their robust mechanical properties, the PNCs can be processed into microgel particles for column reactors, enabling large-scale and continuous-flow catalysis.

[Modeling of Abdominal Wall-Cecum Injury Adhesion and the Anti-adhesion Mechanism of mXG].

OBJECTIVE: To construct the adhesion model of abdominal wall-cecum injury and explore the prevention and treatment effect of modified xyloglucan (mXG) thermosensitive hydrogel on abdominal wall-cecal injury adhesion. METHODS: SD rats were used to construct the abdominal wall-cecal injury adhesion model. Model mice were randomly divided into blank control group (Control), commercial chitosan membrane Control group (Film) and mXG thermosensitive hydrogel group (Hydrogel), each group contained 16 rats.In the Hydrogel group, 1 mL 4% (m/V) mXG solution was smeared on the wound surface of abdominal wall and the cecum, then closed the abdomen after gel was formed (3 min).In the Film group, 2 cm×3 cm chitosan anti-adhesion Film was applied onto the wound surface of the abdominal wall before abdominal closure.In the Control group, 1 mL normal saline was applied onto the wound surface of abdominal wall and the cecum before abdominal closure.On 7 and 14 d after the operation, rats'abdominal cavity was opened by surgery to examine and score the adhesion grade between the abdominal wall and the cecum, with double-blind design.Meanwhile, the adhesion tissue or wound tissue was taken and stained by HE, Masson and Van Gieson to histological evaluate the anti-adhesion effect.The expression of transforming growth factor-ß1 (TGF-ß1) and connective tissue growth factor (CTGF) was determined by immunohistochemical staining as well. Another group of 12 SD rat models were subjected to mXG thermosensitive hydrogel intervention.At the 1 and 6 weeks postoperation, rats main organs such as heart, liver, spleen, lung and kidney were taken for histological examination with HE staining for the purpose of evaluation the toxicity of mXG in vivo. RESULTS: Adhesion grade evaluation results showed that Film group rats occurred mild adhesion, Control group rats occurred severe adhesion, while in Hydrogel group hardly rats occured adhesion, and the differences were statistically significant(P < 0.05). Histological results showed that the Hydrogel group rats recovered well at 7 d after surgery.In healing wound tissue, no mutated tissue was observed, but a certain degree of inflammatory cell infiltration was still existed. At 14 d after surgery, the inflammation cells in the wound were significantly reduced, and the healing tissue containing only a small amount of collagen fibers under the neonatal mesothelial layer.But the other two groups showed different degrees of adhesion at the 7 and 14 d post surgery.Immunohistochemical staining showed that the expression of TGF-ß1 and CTGF in the Hydrogel group were both weaker than those in the other groups, and the difference was statistically significant (P < 0.05). In vivo toxicity tests did not show significant changes in the structure of the organs of mXG gel intervention rats at different time points. CONCLUSION: mXG thermosensitive hydrogel plays a good role in physical isolation during the key period of adhesion formation and effectively prevent the occurrence of cecum-abdominal adhesion.

A core-shell structure QRu-PLGA-RES-DS NP nanocomposite with photothermal response-induced M2 macrophage polarization for rheumatoid arthritis therapy.

Rheumatoid arthritis (RA) is a degenerative joint disease caused by autoimmunity; for the effective treatment of RA while avoiding the side effects of conventional drugs, we have proposed a new therapeutic strategy to eliminate the inflammatory response in RA by regulating the immune system that promotes the transformation of M1-type macrophages to M2-type macrophages. Herein, we designed and synthesized a core-shell nanocomposite (QRu-PLGA-RES-DS NPs), which showed an effective therapeutic effect on RA by accurately inducing the polarization of M2 macrophages. In this system, the quadrilateral ruthenium nanoparticles (QRuNPs) with a photothermal effect were utilized as a core and the thermosensitive molecular poly (lactic-co-glycolic acid) (PLGA) modified with the targeted molecule dextran sulfate (DS) was employed as a shell. Then, the nanocarrier QRu-PLGA-DS NPs effectively improved the water solubility and targeting of resveratrol (RES) through self-assembly. Therefore, the QRu-PLGA-RES-DS NPs significantly enhanced the ability of RES to reverse the M1 type macrophages to the M2 type macrophages through an accurate release. In vivo experiments further demonstrated that the QRu-PLGA-RES-DS NPs could effectively accumulate in the lesion area with an exogenous stimulus, and this significantly enhanced the transformation of the M2 type macrophages and decreased the recruitment of the M1 type macrophages. Furthermore, the QRu-PLGA-RES-DS NPs effectively treated RA by eliminating the inflammatory response; in addition, photoacoustic imaging (PA) of the QRu NPs provided image guidance for the distribution and analysis of nanomedicine in inflammatory tissues. Hence, this therapeutic strategy promotes the biological applications of Ru-based nanoparticles in disease treatment.

Neural network for nonsmooth pseudoconvex optimization with general convex constraints.

In this paper, a one-layer recurrent neural network is proposed for solving a class of nonsmooth, pseudoconvex optimization problems with general convex constraints. Based on the smoothing method, we construct a new regularization function, which does not depend on any information of the feasible region. Thanks to the special structure of the regularization function, we prove the global existence, uniqueness and "slow solution" character of the state of the proposed neural network. Moreover, the state solution of the proposed network is proved to be convergent to the feasible region in finite time and to the optimal solution set of the related optimization problem subsequently. In particular, the convergence of the state to an exact optimal solution is also considered in this paper. Numerical examples with simulation results are given to show the efficiency and good characteristics of the proposed network. In addition, some preliminary theoretical analysis and application of the proposed network for a wider class of dynamic portfolio optimization are included.

Polypeptide nano-Se targeting inflammation and theranostic rheumatoid arthritis by anti-angiogenic and NO activating AMPKα signaling pathway.

Rheumatoid arthritis (RA) is a chronic autoimmune disease and there is a lack of effective treatments. Nitric oxide (NO) plays an important role in inflammatory diseases, but the exact mechanism is not clear. We selected ruthenium complexes [Ru(Phen)2(4idip)](ClO4)2 (Ru) to induce the generation of NO in cells. SeNPs-PEG-RGD@Ru (Se@RuNPs) were prepared by modifying selenium nanoparticles with PEG, RGD and Ru. Se@RuNPs can promote uptake by Human Umbilical Vein Endothelial Cells (HUVECs) and trace the internalization and biodistribution. Experiments showed that Se@RuNPs target the abundant neovascular network of inflammatory sites to induce NO and promote the apoptosis of HUVECs and inhibit the growth of new vessels in local tissue. Moreover, NO activates autophagy by modulating signaling pathways related to AMPKα and mTOR, increasing the flux of autophagy, inhibiting the activity of NF-κB-p65, and modulating the levels of inflammatory cytokines. The exact mechanism of the inflammatory response regulated by NO is revealed. Histopathological analysis showed that the Se@RuNPs effectively reduced synovitis, cartilage corrosion and inflammatory cytokine expression levels, achieving satisfactory therapeutic effects. These unexpected results provide an effective strategy for target treatment of RA.

Biodegradable and injectable thermoreversible xyloglucan based hydrogel for prevention of postoperative adhesion.

Peritoneal adhesion is very common after abdominal and pelvic surgery, which leads to a variety of severe complications. Although numerous pharmacological treatments and barrier-based devices have been investigated to minimize or prevent postoperative adhesion, the clinical efficacy is not very encouraging. In this work, a biodegradable and thermoreversible galactose modified xyloglucan (mXG) hydrogel was developed and the efficacy of mXG hydrogel in preventing postoperative peritoneal adhesion was investigated. The 4% (w/v) mXG solution was a free flowing sol at low temperature, but could rapidly convert into a physical hydrogel at body temperature without any extra additives or chemical reactions. In vitro cell tests showed that mXG hydrogel was non-toxic and could effectively resist the adhesion of fibroblasts. Moreover, in vitro and in vivo degradation experiments exhibited that mXG hydrogel was degradable and biocompatible. Finally, the rat model of sidewall defect-cecum abrasion was employed to evaluate the anti-adhesion efficacy of the mXG hydrogel. The results demonstrated that mXG hydrogel could effectively prevent postoperative peritoneal adhesion without side effects. The combination of suitable gel temperature, appropriate biodegradation period, and excellent postoperative anti-adhesion efficacy make mXG hydrogel a promising candidate for the prevention of postsurgical peritoneal adhesion. STATEMENT OF SIGNIFICANCE: Despite numerous drugs or barrier-based devices have been developed to prevent postoperative adhesion, few solutions have proven to be uniformly effective in subsequent clinical trials. In the present study, we developed a biodegradable and thermoreversible galactose modified xyloglucan (mXG) hydrogel by green enzymatic reaction without using any organic reagents. The developed physical mXG hydrogel not only showed excellent injectability, appropriate gelation time and temperature, but also exhibited excellent biocompatibility and biodegradability both in vitro and in vivo. In addition, mXG hydrogel was easy to handle and could effectively prevent postoperative adhesion without side effects in a rat model of sidewall defect-bowel abrasion. Our study provide a safe and effective postoperative anti-adhesion material which may have potential applications in clinical practice.

Curcumin-loaded redox response of self-assembled micelles for enhanced antitumor and anti-inflammation efficacy.

At present, it has become evident that inflammation plays a critical role in tumor growth; meanwhile, chemotherapeutic agents using nanocarriers have been suggested as a promising strategy in cancer treatment. In this study, novel redox-responsive micelles were prepared from monomethoxy-poly(ethylene glycol)-chitosan-S-S-hexadecyl (C16-SS-CS-mPEG). These micelles were able to carry and deliver drugs into tumor cells. To serve as a control, monomethoxy-poly(ethylene glycol)-chitosan-C-C-hexadecyl (C16-CC-CS-mPEG) was developed in a similar fashion to that used to yield C16-CC-CS-mPEG without a redox-responsive disulfide bond. The cellular uptake mechanisms of both micelles were determined. The efficient intracellular drug release from micelles in MCF-7 cells was further confirmed. Results indicated that curcumin (Cur) could rapidly form C16-SS-CS-mPEG@ Cur micelles when exposed to reducing agents and efficaciously enhance intracellular accumulation. The cytotoxicity assay demonstrated that C16-SS-CS-mPEG@Cur exhibited satisfactory cytotoxicity against MCF-7 cells. Anti-inflammation assay results indicated that C16-SS-CS-mPEG@Cur treatment significantly downregulated tumor necrosis factor (TNF-α) expression and showed good anti-inflammatory effects in tumor microenvironment. Most importantly, antitumor effects in vivo showed satisfactory therapeutic effects with C16-SS-CS-mPEG@Cur. Hence, C16-SS-CS-mPEG@Cur micelles can be useful in tumor therapy.

[Clinical analysis of bilateral same-day myringoplasty for 22 cases with bilateral tympanic membrane perforation].

OBJECTIVE: To investigate the feasibility of bilateral same-day myringoplasty and the indications for myringoplasty for patients with bilateral tympanic membrane perforation, and to summarize relevant experience. METHODS: Twenty-two patients underwent bilateral same-day underlay myringoplasty, and all cases were consistent with the indications for myringoplasty. The preoperative hearing and postoperative hearing at three months were compared, and the postoperative symptoms and complications were observed. Forty patients underwent monaural myringoplasty as the control group over the same period. All cases were followed up for 1 - 3 years. RESULTS: The postoperative hearing was increased by an average of 18 dB, and the rate of closure of tympanic membrane perforation was 93.2% (41/44). There were seven patients with ear fullness after operation in the bilateral myringoplasty group and two patients in the control group (χ(2) = 4.5374, P = 0.0332). There were no differences in the postoperative hearing improvement, the rate of closure and the rates of other discomfort symptoms except for ear fullness between the two groups (P > 0.05). CONCLUSION: It was feasible and safe to perform bilateral same-day myringoplasty for bilateral tympanic membrane perforation, but the postoperative temporary discomfort of bilateral ear fullness should be informed the patients in advance.

[Study of the key points and safety measures during perioperative period in patients with obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To study the safety measures during perioperative period in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), to minimize uvulopalatopharyngoplasty (UPPP) major complications. METHODS: The complications and other relative information of 1446 OSAHS patients treated with UPPP were analyzed. Complications of 1004 OSAHS patients adopted standardized management measures after 2004 and 442 OSAHS patients who performed UPPP before 2003 were compared. RESULTS: Among the 1446 cases of OSAHS surgery, there were 49 cases (3.39%) of difficult intubation; 8 cases (0.55%) intraoperative mild arrhythmia; 13 cases (0.90%) of surgery dangerous situations after extubation; 19 cases (1.31%) of intraoperative primary hemorrhage; 11 cases (0.76%) of mild arrhythmia during the postoperative observation period; 21 cases (1.45%) of uncontrolled hypertension immediately after surgery; 32 cases of secondary hemorrhage a week after surgery. All complications were cured and no death occurred. Compared with those operations before 2003, complications were significantly reduced with enforcement of standardized management of perioperative measures since 2004. The data had significant difference by chi(2) test (P < 0.05). CONCLUSIONS: There are five key points during the perioperative period of OSAHS surgery: preoperative examination, intubation, surgery, postoperative extubation, and postoperative care. Risk factors and complications could be prevented effectively in the above five important processes.

[Molecular etiology of non-syndromic hearing impairment in a Chinese family].

OBJECTIVE: To investigate the molecular etiology of non-syndromic hearing impairment in two patients in a maternal inherited deafness Chinese family. METHODS: Peripheral blood specimens were collected and DNA templates extracted. The complete mitochondrial genomes and GJB2 gene were sequenced in an ABI 3100 Avant sequencer. RESULTS: The proband (III-5) and her elder sister (III-1) were found to carry the mtDNA 12SrRNA C1494T mutation. The GJB2 gene showed no mutations. The proband had the history of using aminoglycosides before hearing loss, and exhibited severe sensorineural hearing impairment; the proband's sister had no history of using aminoglycosides, and showed moderate sensorineural hearing impairment. CONCLUSION: The molecular etiology of each individual patient in a family yaries with individual genetic background.

[Three-axis otoconia maneuver treatment in benign paroxysmal positional vertigo].

OBJECTIVE: To evaluate three-axis otoconia maneuver (TOM) for benign paroxysmal positional vertigo (BPPV). METHODS: The data from twenty BPPV patients who received three-axis otoconia maneuver treatment and 20 BPPV patients who received canalith repositioning (CRP) maneuver treatment were analyzed retrospectively. RESULTS: There were 17 patients received 1 TOM session and 3 patients received 2 TOM sessions while 16 patients received 1 CRP session and 4 patients received 2 CRP sessions. The chi-square (X2) test was used in evaluating the association between two independent samples in a contingency table. Both methods had no statistically significant. The significance level for statistical tests was 5% (alpha = 0.05). CONCLUSIONS: Three-axis otoconia maneuver could be effective used in benign paroxysmal positional vertigo with the advantage of repeatedly practicable and instrumental.