Search

The ultradeep carbonate reservoir in Sichuan Basin is characterized by deep burial depth, high temperature, and strong heterogeneity. In the early stage of production, the vertical well acid fracturing is the main reservoir stimulation method, and the horizontal well stimulation technology is not mature enough to release the production capacity of gas wells. Segmented acid fracturing of the ultradeep horizontal wells currently faces the following problems: the strong heterogeneity of reservoir leads to the difficulty of fine segmentation; the high reservoir temperature requires higher performance of working fluid; the reaction rate between acid and rock is fast and the action distance of acid is short, and there is low fracture conductivity under high closure stress. In view of the above problems, the fine segmented design method was studied, and the high-temperature-resistant authigenic acid and gelling acid systems were developed. The viscosity of authigenic acid is greater than 150 mPa s after shearing at 160 °C and 170 s-1 for 50 min, and the highest acid generation concentration is 4.05 mol/L. The gelling acid system has both the properties of high-temperature resistance and low friction resistance; not only canit meet the requirements of the retarding rate and the corrosion inhibition ability when the reservoir temperature is 160 °C but also the resistance reduction rate is up to more than 70%. By alternating injection of authigenic acid and gelling acid, the acid-etched fracture length and conductivity were, respectively, increased by 80% and 45%. The application of this technology in the horizontal well of the ultradeep carbonate reservoir in Sichuan Basin can increase the productivity by 3 times when compared with the vertical well acid fracturing, and a better stimulation effect has been achieved.

The carbonate gas reservoir of the fourth Member of Upper Sinian Dengying Formation (hereinafter referred as “Deng 4 Member”) is characterized by deep burial, high temperature, low porosity, low permeability and strong heterogeneity in the Gaoshiti-Moxi area of the central Sichuan Basin. In order to effectively enhance the well productivity and gas reservoir development benefits, this paper defines the reservoir stimulation factor by comprehensively considering the drilling, logging and well type characteristic parameters, to carry out quantitative reservoir evaluation. Then, the refined segmentation method was developed by fully considering the reservoir stimulation factor, in-situ stress and borehole condition. In addition, the differential acid fracturing technology was prepared for different types of reservoirs. On this basis, the specified staged acid fracturing technology of horizontal well for strong-heterogeneity carbonate reservoirs was developed and then applied in the field. And the following research results were obtained. First, the reservoir stimulation factor (y) can be used to accurately evaluate the reservoir characteristics. The high quality reservoir has y ≥ 1.0, the moderate reservoir has 0.5 ≤ y

Antimicrobial peptides (AMPs), which hold tremendous promise in overcoming the emergence of drug resistance, are limited in wide clinical applications due to their instability, especially against trypsin. Herein, we designed six peptide mutants based on the cathelicidin CATHPb2, followed by screening. Pb2-1, which showed the best activity against drug-resistant bacteria among these mutants, was selected to be combined with the trypsin inhibitory loop ORB-C to obtain two hybrid peptides: PCL-1 and Pb2-1TI. Notably, both of the hybrid peptides exhibited a remarkable enhancement in trypsin resistance compared with Pb2-1. The tests showed that PCL-1 displayed broad-spectrum antimicrobial activity that was superior to that of Pb2-1TI. In addition, PCL-1 had relatively lower cytotoxicity than Pb2-1TI towards the L02 and HaCaT cell lines and negligible hemolysis, as well as tolerance to high concentrations of salt, extreme pH, and temperature variations. In vivo, PCL-1 effectively improved the survival rate of mice that were systemically infected with drug-resistant Escherichia coli through efficient bacterial clearance from the blood and organs. With regard to mode of action, PCL-1 damaged the integrity of the bacterial cell membrane and attached to the membrane surface while bound to bacterial genomic DNA to eventually kill the bacteria. Altogether, the trypsin-resistant peptide PCL-1 is expected to be a candidate for the clinical treatment of bacterial infections.

A polysaccharide (ESPS) purified from Eupolyphaga sinensis Walker by ion exchange chromatography and gel chromatography was investigated, including its structure characterization and antitumor activity. The results showed that ESPS was composed of rhamnose, fucose, arabinose, xylose, glucose, and galactose in a molar ratio of 7.4: 3.1: 13.9: 9.3: 39.7: 26.5, with the mean weight (Mw) of 2.14 × 104 Da; the main chain of ESPS was mainly composed of → 4) - α - D - Glcp - (1 → and → 3) - β - D - Galp - (1 →, and the side chains were connected to the main chain through the O-6 atom of glucose and O-4 and O-6 atom of galactose. In addition, ESPS promoted the lymphocyte proliferation and inhibited liver cancer cells growth through enhancing lymphocyte activity in vitro, mainly NK cells. Moreover, ESPS markedly stimulated immunity in H22-bearing mice by increasing the spleen and thymus indices and effectively inhibited H22 cell growth in vivo. These data indicated that ESPS was a polysaccharide component possessing high anti-hepatocellular carcinoma activity, representing a potential immunotherapy candidate for the treatment of liver cancer.

Honeysuckle has been used in the treatment of influenza virus infection for thousands of years in China. However, its main active components and the functional mechanisms remain to be elucidated. Here, four honeysuckle extracts, including acids extract, flavonoids extract, total extract and acids-flavonoids mixture, were prepared to clarify the main active antiviral components. The cytopathic effect reduction assay showed that all the four extracts inhibited the replication of influenza viruses H1N1, H3N2 and the oseltamivir-resistant mutant strain H1N1-H275Y. The acids-flavonoids mixture had the strongest inhibitory effects in vitro with EC(50) values of 3.8, 4.1, and > 20 μg/mL against H1N1, H3N2 and H1N1-H275Y, respectively, showing competitive antiviral activity with oseltamivir and ribavirin. Honeysuckle acids extract also showed the most significant antiviral activity in vivo. Oral administration of the acids extract at a dosage of 600 mg/kg/d effectively alleviated viral pneumonia, maintained body weight and improved the survival rate to 30% of the mice infected with a lethal dose of H1N1. The results of time-of-drug addition experiment and neuraminidase (NA) inhibition assay showed that honeysuckle extracts had a broad-spectrum inhibitory effect against influenza virus NAs. The flavonoid extract showed the strongest inhibitory effect on the NA of influenza virus H7N9 with an IC(50) of 24.7 μg/mL. These results suggested that these extracts might exert their antiviral activity by suppressing the release of influenza viruses. Briefly, our findings demonstrate that acids and flavonoids extracts of honeysuckle are the major antiviral active components, and the acids extract has the potential to be developed into an antiviral agent against influenza virus, especially for oseltamivir-resistant viruses.

Thioredoxin (Trx) is a hydrogen acceptor of ribonucleotide reductase and a regulator of some enzymes and receptors. It has been previously shown that significantly elevated levels of Trx expression are associated with the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), but it is not clear how Trx regulates the effects of hydrogen peroxide (H2O2) on myogenic differentiation of BMSCs. Here, we report that rat BMSCs treated with a high dose (150 µm) of H2O2 exhibited a significant reduction in viability, cell cycling, and superoxide dismutase and glutathione peroxidase levels, and an increase in reactive oxygen species and malondialdehyde levels, which was accompanied by reductions in protein kinase B activation and forkhead Box O1, myogenic differentiation 1 and myogenin expression during myogenic differentiation. Furthermore, treatment with recombinant human Trx significantly mitigated the effects of H2O2 on the myogenic differentiation of BMSCs, and this was abrogated by cotreatment with wortmannin [a specific phosphatidylinositol 3‐kinase inhibitor]. In summary, our results suggest that treatment with recombinant human Trx mitigates H2O2‐induced oxidative stress and may promote myogenic differentiation of rat BMSCs by enhancing phosphatidylinositol 3‐kinase/protein kinase B/forkhead Box O1 signaling., Hydrogen peroxide can cause significant peroxidative damage to and inhibit the proliferation and myogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). In this study, we found that recombinant human Trx significantly mitigated hydrogen peroxide‐induced oxidative stress and may promote myogenic differentiation of rat BMSCs by enhancing phosphatidylinositol 3‐kinase/protein kinase B/forkhead Box O1 signaling, which may provide an experimental basis for the BMSC‐based treatment of sarcopenia.

The structural modification of existing AMPs is an effective strategy to develop antimicrobial agents with high-efficiency, low-cost and low-toxicity antimicrobial agents. Methods: Here, we truncated 14-amino-acids at the N-terminus of MSI-78 to obtain MSI and further modified MSI to obtain four peptide analogs: MSI-1, MSI-2, MSI-3 and MSI-4. These peptide mutants were evaluated regarding their antibacterial activity against various sensitive or resistant bacteria; toxicity against mammalian cells or mice; and stability against violent pH, temperature variations and high NaCl concentrations. Finally, we also elucidated the possible mechanisms underlying its mode of action. Results: The results showed that MSI-1 and MSI-3 displayed activity that was superior to that of MSI-78 with MICs of 4-16 μg/ml and MBCs of 8-64 μg/ml, respectively, especially against drug-resistant bacteria, due to the increase in percent helicity and amphiphilicity. However, MSI-3, with higher hydrophobicity and antibacterial activity, had a relatively higher hemolysis rate and toxicity than MSI-1. MSI-1 exerted rapid bactericidal activity and effectively improved the survival rate and wound closure in penicillin-resistant E. coli-infected mice by eliminating bacterial counts in mouse organs or subeschar, further inhibiting the systemic dissemination of bacteria. Additionally, MSI-1 displayed perfect stability against violent pH, temperature variations and high NaCl concentrations and has the ability to circumvent the development of drug resistance. In terms of the mode of action, we found that at the super-MIC level, MSI-1 exhibited direct antimicrobial activity by disrupting the integrity of the bacterial cell membrane, while at the sub-MIC level, it bound to bacterial DNA to inhibit DNA replication and protein expression and ultimately disrupted bacterial biological function. Conclusions: This novel peptide MSI-1 could be a potential candidate for drug development against infection induced by drug-resistant bacteria.

Steering acid fracturing is a new way which can significantly increase oil and gas production. However, it is still unknown how to appropriately use steering acid in carbonate reservoir. Therefore, four true tri-axial acid fracturing experiments were carried out to study fracture initiation and propagation during steering acid fracturing. The experimental results reveal the following. 1. The results of the acid fracturing are easily affected by natural vugs, which can change the direction of the acid-etched fracture propagation. When there are few vugs in the reservoir, the steering acid etches the surface of the acid-etched fractures and forms crowds of acid-etched vugs. 2. When using high pumping rate, it is easy for the steering acid to plug the top of the acid-etched fracture and force the fracture to change its propagation direction. 3. The acid will etch the fracture surface, which results in a strong conductivity. The acid-etching phenomenon is obvious in the area near the wellbore and the turning area. The steering acid etches multiple channels with high conductivities rather than etching the entire area of the fracture surface. 4. Acid fatigue fracturing can effectively reduce the fracturing pressure. However, when using this method, there will be few acid-etched vugs in the area far from the wellbore. When acid is used as fracturing fluid, it would react with the carbonate, and form complex fracture networks.

Incorporating reversible dynamic linkages into the polymer networks endows traditional thermosets with recyclability and reprocessability. However, the facile preparation of recyclable polymer networks with suitable stability and acceptable cost is still a challenge. Among various dynamic linkages, ionic bonds promise a rational dynamic linkage in virtue of suitable stability and facile chemical synthesis. In this study, dynamic ionic bonds were incorporated into the waterborne polyacrylate to form adaptable polymer networks. The carboxyl groups of waterborne polyacrylate provide hydrophilicity and crosslinking sites. Metal salts were added into polyacrylate emulsion to obtain crosslinked polyacrylate via solution casting process. This crosslinking strategy has improved the solvent resistance, creep resistance and tensile strength of linear polyacrylates. The effect of metal cation crosslinking on the water resistance depends on the carboxyl content of linear polyacrylate. Subsequently the mechanical property of pristine and recycled crosslinked polyacrylate was evaluated. Polyacrylate networks crosslinked by divalent metal zinc cation show superior tensile strength and recyclability. Anions of zinc salts have an obvious influence on the enhancement and recyclability of obtained polyacrylate networks. Polyacrylate crosslinked by zinc acetate shows optimal comprehensive performance and application prospect. In addition, the shape memory effect of polyacrylate crosslinked by metal salt zinc acetate was investigated. The shape fixity ratio and shape recovery ratio were 99.8% and 84.9%, respectively. This strategy promises great prospect in designing and preparing customizable high performance recyclable smart thermosets.

A facile strategy of incorporating dynamic carboxylic zinc ion interactions into traditional linear polymers was developed to achieve the recyclability of crosslinked polymers. For newly synthesized polymers, pendant carboxyl can be incorporated into polymer chains during the synthesis process and subsequently crosslinked with zinc acetate. For commercial thermoplastics with only C–C bonds in the backbone, reactive processing offers an alternative approach to prepare vitrimers. This strategy is expected to be an effective approach for high performance recyclable polymer systems.

In this paper, a series of novel form-stable phase change materials (PCMs) containing phosphorus and silica were prepared by transesterification of diethyl phosphite with 1-tetradecanol, 1-hexadecanol and 1-octadecanol, followed by ring-opening reaction and hydrolytic condensation of 2,3-epoxypropoxy propyltrimethoxysilane (silane coupler KH-560). The leakage of pure higher alcohols in molten state was effectively solved due to the support of cross-linked silicon network structure. The co-incorporated phosphorus and silicon would accelerate the formation of chars and improve the thermal stability and fire resistance. The chemical structure and crystalline structure of form-stable PCMs were determined by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Differential scanning calorimeter (DSC) results indicate the melting points are in the range of 29 °C to 55 °C with the latent heat between 81.5 J/g to 116.9 J/g. Thermogravimetric (TG) analyses exhibit improved thermal stability of prepared PCMs compared to pure higher alcohols. The results of scanning electronic microscope (SEM), energy dispersive spectroscope (EDS) and FT-IR confirm the formation of phosphorus-rich and silicon-rich compact chars after thermal treatments. Keywords: Form-stable phase change materials, Higher alcohols, Diethyl phosphite, Silane coupler KH-560, Fire resistance

In this work, we proposed an efficient redox initiating system (ROIS) for free radical polymerization of acrylate-functionalized polyurethanes (APUAs) at room temperature. In this ROIS, cumene hydroperoxide and aliphatic tetraethylenepentamine were used as the oxidizing agent and reducing agent, respectively. Fourier transform infrared spectroscopy results of APUAs and cured polymers show that this ROIS can enable both surface and inner curing of APUAs. The oxygen inhibition can be overcome by the reaction of tetraethylenepentamine with the hydroperoxide produced during the curing process in air atmosphere. The obtained polymer films show good transmittance, high crosslinking density (>86%), good thermal stability and suitable tensile strength (7.64 MPa), which can be applied in coating and adhesive industries. In addition, redox polymerization kinetic was studied by using differential scanning calorimetry.

The Shuangyu gas reservoir in Southwest China is a fracture ultra deep carbonate gas reservoir. Its reservoir buried depth is more than 7000m, and the reservoir temperature is about 160°C. In the early stage, the vertical well acid fracturing method was used to obtain the natural gas production, but the gas production decreased rapidly after acid fracturing, which is difficult to achieve economic and efficient development. Segmented acid fracturing of horizontal wells is an effective way to greatly increase gas production. However, segmented acid fracturing of horizontal wells in Shuangyu ultra deep carbonate gas reservoir faces the following problems: (1)High reservoir temperature, fast acid rock reaction speed and short length of acid corrosion fracture. (2) The diameter of horizontal well is small (114.3mm), packer and other tools can not be put into the wellbore. In this paper, through laboratory tests, an acid fracturing fluid with temperature resistance of 160 °C and friction resistance of 35% of water is developed. The fracturing fluid has the characteristics of high viscosity and high concentration of hydrogen ions, which can not only fracture the formation, but also carry out effective acid etching on the fracture during the injection process. Through the experiment, the temporary plugging agent which can meet the temperature of 160 °C and the combination of temporary plugging agent can form a sealing layer in the fracture with the width of 4mm, and the maximum sealing pressure can reach 20MPa. The research results have been successfully applied in well y616. After fracturing, the daily output of natural gas in well Y616 is 1 million cubic meters, which is more than three times that of the surrounding vertical wells.

Steering acid fracturing is a technique that improves the conductivity of carbonate reservoir. It is widely used in a carbonate reservoir. However, due to the lack of comparative experiments, the application of steering acid to improve the fracturing results is still unknown. Therefore, a series of true triaxial acid fracturing experiments were conducted to study steering acid fracturing in carbonate reservoir. The carbonate specimens used in the experiment were from the Qixia group and Dengsi Member in Sichuan, China. In this study, slick water, cross-linked gel, and self-generating acid were used as ahead fluid to cooperate with steering acid. Experimental results show that (1) the low-viscosity ahead fluid with steering acid can result in more complex fractures; (2) the complexity of fractures is influenced by natural fracture and the viscosity of the ahead fluid; and (3) based on the 3D scanning results of the fracture surface, different ahead fluids will lead to different corrosion results. This study provides useful suggestions on steering acid fracturing design and physical simulation experiments.

Development of novel therapeutic strategies and antibacterial agents against antibiotic-resistant Staphylococcus aureus (S. aureus) is urgent. In this study, antibacterial activities and possible mechanisms of peptide MSI-1 against multiple drug-resistant S. aureus were investigated. Results demonstrated that MSI-1 had potent bacteriostatic activity and bactericidal efficiency against S. aureus, including methicillin-resistant S. aureus (MRSA), vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA), with minimum inhibitory concentrations (MICs) ranging from 4 to 16 μg/mL and bactericidal times from 2-12 h. MSI-1 exhibited a low incidence of developing resistance and additive effects with vancomycin to overcome MRSA and VRSA. Moreover, MSI-1, even at sub-MIC concentrations, inhibited staphyloxanthin (STX) production of S. aureus. This inhibitory effect was unique and effectively sensitized S. aureus to host immune defense. In terms of its modes of action, MSI-1 disrupted the cell membrane of S. aureus by binding to negatively-charged lipoteichoic acid to exert a direct bactericidal effect. Interestingly, MSI-1 interacted with 4,4'-diapophytoene desaturase (CrtN) of S. aureus via ionic bonds, hydrogen bonds, and Pi-Pi or Pi-alkyl interactions, and alanine substitution of the key amino acids contributed to these interactions weakened this STX production inhibition. Thus, in a MRSA-induced skin infection in mice and MRSA/VRSA-induced systemic infection in Galleria mellonella,MSI-1 alleviated staphylococcal scalded skin syndrome to promote mouse skin wound repair and mitigated staphylococcus infection-induced immune melanization to enhance G. mellonella survival. Collectively, MSI-1 has potent antibacterial activity against drug-resistant S. aureus by affecting bacterial viability and exerting its anti-virulence effects. It can be developed as a new antibacterial agent to resist refractory S. aureus infection.

As a fundamental technique to stimulate limestone formations, acid fracturing is now facing the problem of high fracture pressure. The fatigue damage in steel is a powerful strategy to reduce strength. And acidizing is the key step of acid fracturing and a useful tool to minimize limestone fracture pressure. Therefore, the combination of acid fracturing and fatigue treatment was investigated in this study. In addition, the interaction between acid fractures and calcite veins and weathering zones is still unclear. And the geometry of acid fractures in highly deviated wells hasn't been investigated in detail. Hence, there are three primary aims of this study: 1. To investigate the specific performance of fatigue acid fracturing in the limestone. 2. To ascertain the interaction between acid fractures and calcite veins and weathering zones. 3. To clarify the acid fractures morphology in highly deviated wells. Based on the tri-axial acid fracturing system, a sequence of conventional acid fracturing and fatigue acid fracturing experiments were carried out in vertical, highly deviated, and horizontal wells. The experimental results demonstrate that fatigue acid fracturing effectively reduced the fracture pressure and weakened stress shadow effect. And the inclination degree is an influencing factor of fracture morphology complexity. The weathering zone and the calcite blocks had a noticeable impact on fracture propagation process. According to the experimental results, the fatigue acid fracturing will generate fresh insight into limestone formation stimulation treatments.

Background The antibiotic resistance and biofilm formation of pathogenic microbes exacerbate the difficulties of anti-infection therapy in the clinic. The structural modification of antimicrobial peptides (AMP) is an effective strategy to develop novel anti-infective agents. Method Seventeen amino acids (AA) in the longer chain of EeCentrocin 1 (from the edible sea-urchin Echinus esculentus) were truncated and underwent further modification. To produce lead peptides with low toxicity and high efficacy, the antimicrobial activity or cytotoxicity of peptides was evaluated against various multidrug-resistant bacteria/fungi or mammalian cells in vivo/ in vitro. In addition, the stability and modes of action of the lead peptide were investigated. Findings EC1-17KV displayed potent activity and an expanded antimicrobial spectrum, especially against drug-resistant gram-negative bacteria and fungi, attributable to its enhanced amphiphilicity and net charge. In addition, it exhibits bactericidal/fungicidal activity and effectively increased the animal survival rate and mitigated the histopathological damage induced by multidrug-resistant P. aeruginosa or C. albicans in infected mice or G. mellonella. Moreover, EC1-17KV had a poor ability to induce resistance in bacteria and fungi and exhibited desirable high-salt/high-temperature tolerance properties. In bacteria, EC1-17KV promoted divalent cation release to damage bacterial membrane integrity. In fungi, it changed C. albicans membrane fluidity to increase membrane permeabilization or reduced hyphal formation to suppress biofilm formation. Interpretation EC1-17KV is a promising lead peptide for the development of antimicrobial agents against antibiotic resistant bacteria and fungi. Funding This work was funded by the National Natural Science Foundation of China (No. 81673483, 81803591); National Science and Technology Major Project Foundation of China (2019ZX09721001-004-005); National Key Research and Development Program of China (2018YFA0902000); "Double First-Class" University project (CPU2018GF/GY16); Natural Science Foundation of Jiangsu Province of China (No. BK20180563); and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.

The development of novel antifungal agents with high efficacy, low drug tolerance and few side effects is urgent. MSI-1 (GIWKFLKKAKKFWK-NH2), a cationic antimicrobial peptide, may be an attractive antifungal agent because of its structural characteristics, perfect stability against pH and high-temperature/salt, low toxicity towards mammalian cells and low potential for emergence of drug tolerance. In this study, the antifungal activity of MSI-1 in vitro and in a murine model of cryptococcal meningoencephalitis was evaluated. Zeta potential assay, flow cytometry, fluorescence microscope, transmission electron microscopy and microscale thermophoresis were performed to clarify the mechanisms underlying MSI-1 against C. neoformans. The results showed that MSI-1 exerted effective anti-cryptococcal activity in vitro, with MICs of 8−16 μg/mL and MFCs of 8−32 μg/mL, and in a C neoformans-infected mouse model, with significantly improved animal survival, decreased production of pro-inflammatory cytokines and alleviated lung injury, because the potent and rapid fungicidal activity of MSI-1 could effectively eliminate fungal counts in mouse organs. We confirmed that the positively charged peptide bound to C. neoformans by electrostatic attraction after interacting with glucuronoxylomannan (the primary component of C. neoformans capsule). Subsequently, MSI-1 increased the membrane fluidity of fungal cells and the cell membrane permeability, causing destabilized membrane integrity and leading to the final death of fungi. Collectively, MSI-1 possessed potent anti-cryptococcal activity via its notable membrane disruption effect and may be a potential candidate for use in antifungal infection induced by C. neoformans, especially azole-resistant cryptococcus.

The Shuangyu gas reservoirs in China has a reservoir depth of more than 7000 m and a reservoir temperature of 160 °C. It is a fractured porous carbonate gas reservoir, and the gas wells mainly establish production by acid fracturing. In the early stage, the Shuangyu gas reservoirs was mainly developed with vertical wells. After acid fracturing, the natural gas production was low and declined rapidly. To obtain higher natural gas production, a large number of highly deviated wells have been deployed in the Shuangyu gas reservoirs. Because the diameter of a highly deviated well in the Shuangyu gas reservoirs is small, a subsection tool cannot be operated inside it, so it can only adopt temporary plugging acid fracturing. In this paper, a resistance-reducing acid with low friction resistance is optimized and a set of temporary plugging agents with low dissolution rate in the acid solution are selected through laboratory tests. A dynamic temporary plugging instrument is used to evaluate the plugging ability of a temporary plugging agent with different concentrations and combinations for fractures with widths of 2 and 4 mm, developing a temporary plugging agent formulation suitable for temporary plugging segmented acid fracturing of the Shuangyu gas reservoirs. In the YY666 well, the application of the research results of this paper has successfully achieved a three-stage temporary plugging acid fracturing, and the natural gas production after fracturing has been increased by 3-4 times compared with those of surrounding wells.

The currently available drugs against influenza A virus primarily target neuraminidase (NA) or the matrix protein 2 (M2) ion channel. The emergence of drug-resistant viruses requires the development of new antiviral chemicals. Our study applied a cell-based approach to evaluate the antiviral activity of a series of newly synthesized benzoic acid derivatives, and 4-(2,2-Bis(hydroxymethyl)-5-oxopyrrolidin-l-yl)-3-(5-cyclohexyl-4H-1,2,4-triazol-3-yl)amino). benzoic acid, termed NC-5, was found to possess antiviral activity. NC-5 inhibited influenza A viruses A/FM/1/47 (H1N1), A/Beijing/32/92 (H3N2) and oseltamivir-resistant mutant A/FM/1/47-H275Y (H1N1-H275Y) in a dose-dependent manner. The 50% effective concentrations (EC50) for H1N1 and H1N1-H275Y were 33.6 &mu, M and 32.8 &mu, M, respectively, which showed that NC-5 had a great advantage over oseltamivir in drug-resistant virus infections. The 50% cytotoxic concentration (CC50) of NC-5 was greater than 640 &mu, M. Orally administered NC-5 protected mice infected with H1N1 and H1N1-H275Y, conferring 80% and 60% survival at 100 mg/kg/d, reducing body weight loss, and alleviating virus-induced lung injury. NC-5 could suppress NP and M1 protein expression levels during the late stages of viral biosynthesis and inhibit NA activity, which may influence virus release. Our study proved that NC-5 has potent anti-influenza activity in vivo and in vitro, meaning that it could be regarded as a promising drug candidate to treat infection with influenza viruses, including oseltamivir-resistant viruses.

In order to investigate the deterioration of the elastic modulus and fracture toughness of corroded concrete, three-point bending (TPB) tests were conducted by using corroded concrete specimens. The initiation load, the maximum load, the P-CMOD (loads versus crack mouth opening displacements) curves and the stress-strain curves were measured. Meanwhile, the deterioration near crack tips of the corroded specimens was observed with the aid of scanning electronic microscopy (SEM). Under the simulated acid solutions, the corrosion depth near crack tips gradually grows with the increase of corrosion time, and finally the concrete microstructures are porous and loose and microcracks are developed, which will deteriorate concrete material parameters, such as elastic modulus and fracture toughness. The test results show that subcritical propagation occurs during the loading progress from the initiation load to the maximum load, and the initiation toughness is about 80%–85% of the fracture toughness of the corroded concrete. For the specimens immersed in pH 2.5 and 3.5 solutions, both the fracture toughness and the elastic modulus increase in the early stage and then decrease with the increase of corrosion time, whereas for the specimens immersed in pH 1.5 solutions, both the elastic modulus and fracture toughness decrease almost linearly with immersion time. H+ and SO 4 2 - are two main factors in the deterioration of concrete in the simulated acid solutions.

Tributyl citrate (TBC) and acetyl tributyl citrate (ATBC), as phthalate alternative plasticizers, show limited application due to low migration resistance, high volatilization rate and intense respiratory irritation. Meanwhile, the developed pure citrates, such as butyryl trihexyl citrate (BTHC) due to its high cost, and triisooctyl citrate (TOC) and acetyl triisooctyl citrate (ATOC) due to their low absorption property, are not attractive plasticizers to manufacture phthalate-free poly(vinyl chloride)s (PVCs). In this study, we developed an effective method to synthesize acetylated mixture of citrate esters (ATMC) composed of acetyl (dibutyl-monoisooctyl) citrate, acetyl (monobutyl-diisooctyl) citrate, and a small amount of ATBC and ATOC, as an alternative for phthalate plasticizers. ATMC combines the advantages of ATBC in being easily absorbed and ATOC in having good migration resistance. Characterization results showed that the dynamic viscosity, absorption property and plasticizing efficiency of ATMC11 (1:1 molar ratio of n-butyl alcohol to 2-ethylhexanol) were similar to those of di(2-ethylhexyl) phthalate (DEHP). The thermal volatilization and migration of ATMC11 were less than those of ATBC, and were comparable to those of DEHP, which could be attributed to the improved compatibility with PVC. The performance of ATMC11 was improved compared with that of the mixture of ATBC and ATOC. As an environmental bio-based plasticizer, ATMC11 was demonstrated as a biologically safe plasticizer by biological safety evaluation tests. Therefore, ATMC11 with excellent comprehensive performances and low cost can be candidate as an ideal phthalate alternative for soft PVC formulations.

A carboxy modified long-chain diol (CMLCD) was synthesized for the first time through esterification of pyromellitic dianhydride (PMDA) and polytetramethylene glycol 1000 (PTMG1000). Waterborne polyurethane (WPU) was prepared based on an organic solvent-free and self-catalytic process, using synthesized CMLCD as a hydrophilic diol. The CMLCD has self-catalytic ability to the reaction of hydroxyl and isocyanate during the prepolymerization, which can greatly shorten the preparation period and avoid the utilization of highly toxic catalyst such as dibutyltin dilaurate. Importantly, the prepared WPU has narrow particle size distribution with the average particle size of 137 nm, which leads to good stability even centrifugated at 3000 rpm. Mechanical test results show that the WPU film possesses good mechanical performance with the tensile strength of 59.3 MPa and elongation at break of 819.2%. Additionally, the prepared WPU film has high water resistance. This study is attractive for future green WPU in industrial production and application.

Novel poly(carbonate-co-amide) (PCA) block copolymers are prepared with polycarbonate diol (PCD) as soft segments, polyamide-6 (PA6) as hard segments and 4,4’-diphenylmethane diisocyanate (MDI) as coupling agent through reactive processing. The reactive processing strategy is eco-friendly and resolve the incompatibility between polyamide segments and PCD segments in preparation processing. The chemical structure, crystalline properties, thermal properties, mechanical properties and water resistance were extensively studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermal gravity analysis (TGA), Dynamic mechanical analysis (DMA), tensile testing, water contact angle and water absorption, respectively. The as-prepared PCAs exhibit obvious microphase separation between the crystalline hard PA6 phase and amorphous PCD soft segments. Meanwhile, PCAs showed outstanding mechanical with the maximum tensile strength of 46.3 MPa and elongation at break of 909%. The contact angle and water absorption results indicate that PCAs demonstrate outstanding water resistance even though possess the hydrophilic surfaces. The TGA measurements prove that the thermal stability of PCA can satisfy the requirement of multiple-processing without decomposition.

Baicalin was identified as a neuraminidase (NA) inhibitor displaying anti-influenza A virus (IAV) activity. However, its poor solubility in saline has limited its use in the clinic. We generated sodium baicalin and showed that it exhibited greatly increased solubility in saline. Its efficacy against oseltamivir-resistant mutant A/FM/1/47-H275Y (H1N1-H275Y) was evaluated in vitro and in vivo. Results showed that 10 μM of sodium baicalin inhibited A/FM/1/47 (H1N1), A/Beijing/32/92 (H3N2) and H1N1-H275Y in MDCK cells in a dose-dependent manner, with inhibitory rates of 83.9, 75.9 and 47.7%, respectively. Intravenous administration of sodium baicalin at 100 mg/kg/d enabled the survival of 20% of H1N1-H275Y-infected mice. The treatment alleviated body weight loss and lung injury. Moreover, sodium baicalin exerted a clear inhibitory effect on NAs. The IC50 values of sodium baicalin against H1N1-H275Y and cells-expressing A/Anhui/1/2013-R294K (H7N9-R294K) NA protein (N9-R294K) were 214.4 μM and 216.3 μM. Direct interactions between sodium baicalin and NA were observed, and we simulated the interactions of sodium baicalin with N9-R294K and N9 near the active sites of OC-N9-R294K and OC-N9. The residues responsible for the sodium baicalin-N9-R294K and sodium baicalin-N9 interactions were the same, confirming that sodium baicalin exerts effects on wild-type and oseltamivir-resistant viral strains.

Baicalein and baicalin are active components of the Scutellaria baicalensis Georgi and both have broad anti-tumor activity. However, how and whether baicalein and baicalin inhibit colon cancer is unclear. Here we demonstrate that baicalein and baicalin can significantly inhibit human colon cancer cell growth and proliferation. Furthermore, both can induce cell cycle arrest, and suppress cancer cell colony formation and migration. The suppressive effects are mechanistically due to the induction of colon cancer cell apoptosis and senescence mediated by baicalein and baicalin, respectively. Furthermore, we revealed that baicalin-induced senescence in tumor cells is due to its inhibition of telomerase reverse transcriptase expression in tumor cells, and that MAPK ERK and p38 signaling pathways are causatively involved in the regulation of colon cancer cell apoptosis and senescence mediated by baicalein and baicalin. In addition, our in vivo studies using human colon cancer cells in humanized mouse xenograft models, further demonstrated that baicalein and baicalin can induce tumor cell apoptosis and senescence, resulting in inhibition of tumorigenesis and growth of colon cancer in vivo. These data clearly suggest that baicalein and baicalin have potent anti-cancer effects against human colon cancer and could be potential novel and effective target drugs for cancer therapy.

The polysaccharide SEP has been reported to activate NK and T cells via TLR2/4. Here, the combination of gemcitabine (GEM) and SEP against HepG-2 was investigated. SEP apparently enhanced antitumor activity of gemcitabine against liver cancer through stimulating NKG2D and DAP10/Akt pathway to activate NK cells. The NKG2D upregulation could improve the sensitivity of NK-92 cells targeting to its ligand MICA expressed on HepG-2 cells. Meanwhile, GEM up-regulated MICA expression and attenuated soluble MICA secretion through inhibiting ADAM10 expression, which in turn enhanced the cytotoxicity of NK-92 cells against cancer cells. SEP remarkably enhanced GEM antitumor activity with an inhibitory rate of 79.1% in an H22-bearing mouse model. Moreover, SEP reversed atrophy and apoptosis caused by GEM in both spleen and bone marrow through suppressing ROS secretion in vivo. The data indicated that the combination of SEP and GEM is a potential chemo-immunotherapy strategy for liver cancer treatment clinically.

In this study, two components based polyethylene glycol (PEG)/thermosetting solid-solid phase change material composites as novel form stable phase change material (FSPCM) were successfully prepared via free-radical polymerization. One of the components consists of PEG-based polyurethane acrylate prepolymer and extra pristine PEG. Another component is made up of 1,6-hexanediol diacrylate and benzoyl peroxide. The extra pristine PEG with low viscosity at melting state was used as diluents to decline the melting viscosity of PUA and served as phase change functional chains of the FSPCMs, endowing the FSPCM with high latent heats and flexible application ability for thermal energy storage. The chemical structure, crystalline performances, phase change properties and thermal reliability and stability of prepared FSPCMs were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, polarizing optical microscopy, differential scanning calorimetry and thermogravimetry analysis, respectively. The leakage test results show that the maximum content of PEG in novel FSPCM without any leakage above the melting point of PEG is 85 wt%. The DSC analysis results show that the novel FSPCMs have high latent heats and the latent heats efficiency of novel FSPCMs is significantly higher than that of the traditional FSPCMs. The prepared FSPCMs exhibit good thermal reliability and stability from the thermal cycling test and TG analysis.

Acid fracturing of carbonate rock starts with formation breakdown and fracture propagation caused by stimulation fluids. The effectiveness of acid fracturing largely depends on the behavior of fracture propagation. While fracture propagation of fractured carbonate rock is greatly influenced by natural fractures and fluid types. So far, some scholars have studied the influence of nonreactive fracturing fluid on fracture propagation, but the comparison of effect between nonreactive fracturing fluid and reactive fracturing fluid on fracture propagation is rarely noticed. In this paper, true tri-axial experiments on carbonate rock (200 mm × 200 mm × 200 mm) are presented; the experiment made a comparative study on the effect of nonreactive fracturing fluid (water, guar fracturing fluid) and reactive fracturing fluid (self-generated acid, gelled acid, VES acid) on fracture propagation in fractured carbonate rock. Besides, fracture morphology was revealed through CT scan and 3D reconstruction technology. In this way, influence of natural fractures and fluid types on hydraulic fracture propagation during acid fracturing was quantitatively analyzed. Results show that these two factors indeed exert great impact on fracture propagation behavior. As acid is more conducive to connection of natural fractures, hydraulic fractures induced by acid can propagate along natural fractures after initiating from natural fractures, and the process would not be restricted by maximum horizontal stress. As a result, a longitudinal fracture parallel to the wellbore is formed. Compared with self-generated acid and gelled acid, VES acid is more liable to connect natural fractures and form complex fracture network during acid fracturing. No matter reactive or nonreactive fracturing fluid is applied to conduct fracturing experiments, hydraulic fracture propagation in carbonate rock with few natural fractures would be restricted by maximum horizontal stress, and transverse fractures perpendicular to the wellbore would be formed after fracturing. In addition, breakdown pressure of rock samples is also affected by natural fractures and fluid types. To be specific, gelled acid decreases rock's breakdown pressure to the greatest extent when numerous natural fractures exist in the rock; the breakdown pressure caused by gelled acid is only 56.7% of which caused by water. However, the gelled acid has little contribution to decrease the breakdown pressure of the carbonate rock with few natural fractures. In a word, the experiment reveals effect of stimulation fluid types on hydraulic fracture propagation in fractured carbonate rock, which provides some guidance for acid-fracturing treatment in carbonate reservoir.

Thermoplastic shape memory polymers (SMPs) as smart materials have a great challenge in adjusting trigger temperature ( T t ) for practical device application with high fixity and recovery ratio (>99%). The thermoplastic SMPs based on triblock copolymers have been designed via reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization. The T t can be manipulated facilely, as designed, with the narrow temperature interval between adjacent T t s (only 10 °C), indicating the high resolution of temperature in molecular design of SMPs. The as-designed SMPs have good shape memory ability and the reprogramming ability of shape memory behaviors. This approach can direct the molecular design of thermoplastic SMPs with tailor-made T t via RAFT emulsion polymerization.

PEG based thermosetting phase change materials (PCMs) have been frequently employed for thermal energy storage in building and other fields due to the low cost, no toxic, no corrosive, good thermal properties and no leakage in phase change process. In this article, thermosetting PCMs with polyethylene glycol (PEG) as phase change functional chain and polyaryl polymethylene isocyanate terminated polycarbonatediol (PCD) as curing agent were prepared through a facile and solvent-free bulk polyaddition. This preparation strategy can provide novel mean to design and synthesize PEG based thermosetting PCMs with different structure and performances according to the specific requirement. Moreover, the introduction of PCD will further improve the performance of PCMs. The chemical structure, crystalline properties, phase change properties, thermal reliability and stability of prepared PCMs were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarizing optical microscopy (POM), differential scanning calorimetry (DSC), accelerated thermal cycling testing and thermogravimetric analysis (TGA), respectively. FTIR spectra showed that the PEG based thermosetting PCMs were successfully synthesized. XRD and POM results indicated the similar spherulite structure of virgin PEG and prepared PCMs, and the crystallinity and crystal size of PCMs are affected by the introduction of curing agent. Meanwhile, DSC measurements showed that prepared PCMs have good phase change properties. Accelerated thermal cycling and TGA testing proved the excellent thermal reliability and thermal stability of prepared PCMs.

Antistatic-polyamide elastomers composed of poly(urethane-urea-amide) (PUUA) and NaSCN was successfully synthesized through in-situ reactive processing in double-screw extruder. The obtained antistatic-polyamide elastomers can be employed as solid polymer electrolyte to improve the surface conductivity of polymers. The effect of PUUA composition, NaSCN content, temperature and relative humidity on the surface resistivity of antistatic-polyamide elastomer was extensively studied by surface resistivity. The results showed that the surface resistivity of antistatic-polyamide elastomer was slightly influenced by temperature and relative humidity, and can satisfy the application of antistatic materials requirement. Moreover, thermalgravity analysis (TGA), tensile test and scanning electron microscopy (SEM) were used to evaluate the thermal stability, mechanical properties and morphology of fracture face of antistatic-polyamide elastomers. TGA results demonstrated that antistatic-polyamide elastomers have a good thermal stability with the onset decomposition temperature exceed 280?. Tensile tests revealed that the prepared antistatic-polyamide elastomers possess good mechanical properties. SEM showed that the antistatic ability of antistatic-polyamide elastomer is relative to the ion-conductive channels or network formed by the PUUA and NaSCN particles.

The polyamide-6 based poly(ether-block-amide) (PEBA) multiblock copolymers were reactively prepared in typical processing equipment, torque rheometer. The reactive processing conditions of PEBA were discussed in details on the base of the tensile strength as the main quantization parameter and the torque rheological curves. The optimized reaction temperature, reaction time, and rotational speed were 150°C, 10 min, and 40 rpm respectively. The chemical structure, tensile properties, thermal transition, thermal stability, water absorption, and solubility in organic solvents of PEBA prepared in optimized reaction conditions were characterized by Fourier transform infrared spectroscopy, tensile testing, differential scanning calorimetry, thermogravimetric analysis, and soaking testing in water and organic solvents. The tensile strength and elongation at break of PEBA are 35.9 MPa and 580% respectively. The glass transition temperature and melting temperature of soft segment of PEBA are −50 and 15°C, respectively; the glass transition temperature and melting temperature of hard segment of PEBA are 50 and 140°C respectively. Meanwhile, the PEBA has low water absorption, robust organic solvent resistance, and good thermal stability. The optimization process of PEBA will give the deep understanding of reactive processing of polymer materials.

Poly(lactic acid) (PLA)/poly(1,4-butylene adipate) (PBA) blends with different PBA content were directly prepared via melt blending as potential biodegradable packaging materials. PBA with 1000 g/mol number average molecular weight was served as plasticizer to improve PLA properties. The morphological, thermal and mechanical properties of the blends were extensively investigated by scanning electron microscope (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile and impact tests and thermogravimetry (TG). The results show that the degree of crystallinity of PLA increased with increasing PBA content. The addition of PBA (20 wt%) result in the positive effect on the elongation at break and toughness, which increased from 7.9% to 74.4% and from 3.9 kJ/m2 to 12.6 kJ/m2, respectively. Meanwhile, the migration tests indicate that PBA exhibits excellent lower migration ratio compared with citrate esters.

The symmetric polystyrene- block -poly( n -butyl acrylate)- block -polystyrene (SAS) triblock copolymers with wide applicable temperature range have been designed and synthesized via reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization. The high poly( n -butyl acrylate) (PBA) block content introduced will endow the SAS with the ability of working as film-forming materials. The microphase separation and mechanism of wide applicable temperature range were investigated by differential scanning calorimetry and dynamic mechanical analysis (DMA). The static and dynamic mechanical properties, visible light transmittance, water resistance and thermal stability of SAS were also characterized by tensile test, DMA, spectrophotometer, water absorption and thermogravimetric analysis. The tensile strength decreases and elongation at break increases with the PBA block content of SAS increasing from 50 wt.% to 70 wt.%. The maximum elongation at break reaches 707%. The broad thermoplastic elastic region from −40 °C to 80 °C works well in the surrounding of a big temperature difference due to the PBA block in rubbery state and the PSt block in glassy state. The SAS has high transmittance, low water absorption and favorable thermal stability. This research will provide a reference for film-forming materials with wide applicable temperature range.

A new interfacial modifier containing silicon and phosphorus has been developed to improve the flame retardancy and mechanical properties of ethylene-vinyl acetate (EVA)/alumina trihydrate (ATH) composites. The EVA/ATH composites were prepared via blending EVA pellets with different kinds of ATH particles. The results showed a synergistic effect of phosphorus-containing silane coupling agent (DOSA) and ATH particles on the flame retardancy of EVA composites. When compared with pure EVA of 19.1, the limiting oxygen index (LOI) value was increased to 31.4. This was the result of the formation of a charred layer and the enhanced compatibilities between inorganic particles and polymer matrix. The experimental results also showed that the modified ATH particles by using synthesized DOSA led to an increase in mechanical properties. The improvement on the mechanical and thermal properties of EVA composites was mostly attributed to the better dispersion ability of the modified ATH particles in the polymer matrix and a synergistic effect between the DOSA and ATH particles. The char-formation ability of EVA composites has also been analyzed and the synthesized DOSA has shown a positive effect.

Here, we investigated whether I 4 , which was initially developed as a hypoglycemic agent, possesses anti-atherosclerotic activity and attempted to elucidate the probable mechanism of action underlying this activity. ApoE −/− mice were fed a Western diet and simultaneously administered I 4 , glimepiride, or pioglitazone once daily for 12 weeks, and the atherosclerotic vascular lesions, lipid content, and expression levels of LOX-1, ICAM-1, VCAM-1 and Bax/Bcl-2 in mouse aortas were assessed. RAW264.7 macrophage-derived foam cells were obtained via ox-LDL stimulation to investigate the lipid-lowering, anti-atherosclerotic inflammation and anti-apoptotic effect of I 4 . The data indicated that I 4 significantly decreased the lipid accumulation in the circulation and tissue, especially for TG and FFA levels (p vs model group), alleviating the arterial and liver lesions induced by lipotoxicity. Its lipid-reducing effects may due to LOX-1and CD36 expression suppression. I 4 , at doses of 20 mg/kg and 10 mg/kg, significantly decreased serum IL-6, IL-1β, and TNF-α production and suppressed the expression of p-ERK, p-p38, VCAM-1 and ICAM-1 protein. I 4 attenuated atherosclerotic inflammation by blocking NF-κB nuclear translocation, suppressing MAPK/NF-κB signaling pathway and diminishing NF-κB-VCAM-1 promoter region binding. Additionally, I 4 suppressed p-p53 and cleaved-caspase-3 expression to inhibit foam cell apoptosis induced by ox-LDL uptake. Overall, I 4 exerts potent inhibitory effects on atherosclerosis onset and development.

Environmental protection and resources exhaustion have become the two major obstacles that the human race faces. Moreover, conventional thermoset polymers, which have been extensively applied in various fields, are difficult to be reprocessed and recycled thereby resulting in a wastage of resources and environmental pollution owing to their chemical crosslinks. Therefore, vitrimers may be a good option to solve this problem. In this study, renewable castor oil was used as the raw material to synthesize multifunctional polyurethane-vitrimers (PUVs), whose intrinsic carbamate bonds undergo transcarbamoylation reactions in the presence of a catalyst. Reprocessing experiments have shown that reprocessed PUVs have nearly the same excellent tensile property compared with the pristine PUVs and have significant potential for future engineering applications. Subsequent studies have indicated that crosslinked networks have properties of thermally-induced dual-shape memory effect (dual-SME) and self-welding due to transesterification reactions of carbamate bonds. As the current methods of dealing with abandoned thermoset polyurethanes have drawbacks, it can be anticipated that our findings will create significant benefits for our life.

The bulk-biodegradable solid–solid phase change materials (SSPCMs) based on phase change polyethylene glycol (PEG) were synthesized by solvent-free polyaddition. On the basis of the fact that the water absorption is up to 800 mass% and that the poly(ethylene oxide) molecular chains can be degraded by microorganisms, the bulk-biodegradable mechanism of SSPCMs was put forward and studied. The X-ray diffraction patterns and the polarizing optical microscopy images show the SSPCMs possess the defective crystal and small grain compared with PEG. The differential scanning calorimetry data demonstrate the melting temperature and enthalpy of the synthesized SSPCMs are, respectively, 41 °C and 128 J g−1. The bulk-biodegradable SSPCMs have the preeminent thermal reliability and the high thermal stability due to the onset thermal degradation temperature above 302 °C, which will give a good insight into bulk-biodegradable PCM system.

A series of poly(urethane-urea-amide) thermoplastic elastomers (PUUAs) based on polytetrahydrofuran (polytetramethylene glycol, PTMG), nylon-6 and 4,4′-diphenylmethane diisocyanate were synthesized through reactive processing. This method solved the incompatibility of nylon-6 and PTMG, and these model elastomers were used to gain insight into the structure–property relations of block polymers. The target products were solvent resistant, transparent and melting-processable. Fourier transform infrared spectroscopy, XRD, DSC, TEM, dynamic mechanical analysis, tensile testing and TGA were used to study the structure, crystallization, morphology, mechanical properties and thermostability of the PUUAs. The Fourier transform infrared results proved the successful preparation of PUUAs from nylon-6 and PTMG. TEM examination showed that all samples exhibit microphase separated morphology with the nylon-6 domain dispersed in the PTMG phase. The results of tensile testing indicated that the elastomers exhibit excellent mechanical properties with stress at break and strain at break exceeding 40 MPa and 600% respectively. The TGA results implied that the PUUAs can be fabricated by transitional processing at proper temperature without any thermodegradation. These favorable features were related to the microphase separated structure of the PUUAs. © 2016 Society of Chemical Industry

Aesculin, a natural product from the traditional and widely-used Chinese medicine named Cortex fraxini, has attracted attention as a novel therapeutic modulator of inflammation. However, little is known about its effect on ulcerative colitis (UC). This study aimed to investigate the protective effects and mechanisms of aesculin on colitis. The results showed that, few cytotoxicity of aesculin were shown in vivo and in the RAW264.7 macrophages, while aesculin significantly relieved the symptoms of DSS-induced colitis and restrained the expression of inflammatory factors including iNOS, IL-1β, TNF-α in both peritoneal macrophages and colonic tissues from DSS-induced mice and RAW264.7 macrophages. Of note, aesculin attenuated the activity of NF-κB signaling while promoted the nuclear localization of PPAR-γ in both rectal tissues from DSS-induced mice and LPS-stimulated macrophages. These findings demonstrated that the protection of aesculin against ulcerative colitis might be due to its regulation on the PPAR-γ and NF-κB pathway. Thus, aesculin could serve as a potential therapeutic agent for the treatment of ulcerative colitis.

More than 30% of carbonate reservoirs in the Tarim oilfield and XiNan oil-gas field are naturally fractured-vuggy reservoirs, of which the production is high in most cases and economic returns can be achieved within a short period of time. Acid fracturing is one of the key technology for development of such naturally fractured-vuggy reservoirs. Mud overflow and loss may be emerged at the same time while drilling fractured-vugular carbonate, once it happened, the well control will become complicated. So, the wellbore is drilled a certain distance up or transversal to these huge caves or natural fractures, and acid fracturing will be executed to connected the reservoirs to obtain the hydrocarbon in the reservoir. Acid-fracturing design of fractured-vugular carbonate is based on the relationship between the wellbore and fractured-vugular reservoirs. The acid fracturing design in naturally fractured-vuggy carbonate reservoir is different from the conventional one, it should be optimized based on the spatial positions of the fracture-vuggy body identified via geophysical prospecting, the wellbore and the distance between the two. In the case that the wellbore precisely reaches the top of the fracture-vuggy body, good oil and gas show or overflow is frequently happened. At this moment, drilling ceases and the wellbore are cemented and completed. The small-scale acid fracturing treatment is then carried out, and connectivity between etched fractures and the top of the fracture-vuggy body will lead to high hydrocarbon production. If a certain distance exists between the wellbore and fracture-vuggy reservoirs, 3D seismic imaging will be adopted to calculate the vertical distance between the center of the storage body and the wellbore, which is then used to optimize the injected fluid volume, pump rate and acid fracturing techniques. To create connectivity with the fracture-vuggy storage body relatively far away from the wellbore, acid fracturing involving preflush or multi-stage injection is used. Pressure drops by several ∼ several tens of MPa usually occur as the artificial fracture propagates into the fracture-vuggy body. After fracturing penetrating into the fracture-vuggy body, acid injection starts. During the early acid injection, the pump rate is raised up for longer etched length inside the fracture. It is then lowered during the late acid injection to improve the conductivity of etched fractures. If multiple fracture-vuggy bodies exist near the wellbore, the temporary diverting acid-fracturing will be treated, optimized with respect to the distance between the wellbore and different fracture-vuggy storage bodies, spatial relationship between the maximum principal stress direction and fracture-vuggy storage body and the trend of natural fractures, will be implemented to communicate with multiple naturally fractured vuggy reservoirs. This acid fracturing integrating geophysical prospecting and wellbore trajectory has been applied in hundreds of wells in the Tarim oilfield. Moreover, the success rate of such acid fracturing treatments is increasing with the advancement in the characterization of the fracture-vuggy reservoirs.

The Sinian dolomite reservoirs in Southwest Oil and Gas Field, China, are characterized by HTHP, high stress, low porosity and permeability, large thickness, and presence of natural fractures and holes. Highly deviated well multistage acid fracturing can help expand the contacting area between wellbore and reservoir, thereby increasing the well production. Through experiments, acid fracturing simulations, staging optimization and field applications, some conclusions were obtained. Large-scale physical modelling experiments and numerical simulations show that, given the high horizontal stress difference, presence of natural fractures, can induce a complex fractures networks. The acid systems with different viscosities, such as self-generating acid, gelled acid and diverting acid, are optimized to, in conjunction with highrate injection and temporary diverting, improve the stimulated reservoir volume and conductivity of acid-fractures in the dolomite reservoirs. The combination of mechanical packers and sliding sleeves facilitate the effective isolation of HTHP dolomite reservoir. The positions of the sliding sleeves are designed according to the high-quality reservoir intervals determined by logging interpretation. The lateral of deviated well is 480m-970m long and stimulated by acid fracturing in 3-6 stages. The post-fracturing tracer testing proves the effectiveness of isolation. This technology was applied for 6 wells, with a daily gas production of (21–110) × 104m3/d after acid fracturing. It provides a new method to increase the production of highly deviated wells or horizontal wells in deep carbonate reservoirs.