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Hydraulic fracturing and self-diverting acid based on viscoelastic surfactant are effective methods to improve the production of low permeability reservoirs. However, surfactants as the main agents of the fluids have a certain impact on oil and gas exploration. The adsorption of surfactant on the rock may change the hydrocarbon flow path and greatly influence the recovery rate. This plagues people in choosing surfactant in reservoir stimulation. In order to make people have a clearer understanding of this issue, we synthesized four representative quaternary ammonium surfactants, including single/Gemini -cationic surfactant and single/Gemini zwitterionic surfactant. The critical micelle concentration (CMC), the adsorption and wettability were researched. The adsorption mechanism of viscoelastic surfactants was investigated through the static adsorption properties and wettability studies of different types of viscoelastic surfactants on carbonate rocks and sandstones with varying concentrations and temperatures. This has important guiding significance for choosing surfactants in the reservoir stimulation.

A new dibenzylamine-quinoline derivative (DEEQ) was synthesized and investigated as a corrosion inhibitor for mild steel in 15% HCl solution in various ways, including via weight loss measurements, contact angle measurements, electrochemical measurements (EIS), scanning electron microscopy (SEM), scanning Kelvin probe (SKP) and theoretical calculations. The experimental results revealed that DEEQ is an effective corrosion inhibitor for oil and gas acidification. In an oil–water two-phase system, the wettability of mild steel can be changed by adsorption, while obeying the Langmuir adsorption isotherm. Finally, quantum chemical calculations and molecular dynamic simulation parameters further show a definite correlation between the theoretical and experimental results.

Understanding how host plant chemistry affects invasive insects is crucial for determining the physiological mechanism of host use and predicting invasive insect outbreak and damage on hosts. Here, we examined the effects of plant nutrition and defensive chemicals on host preference and performance of adults and larvae of the invasive potato tuberworm, Phthorimaea operculella (Zeller; Lepidoptera: Gelechiidae), on four native (Solanum tuberosum, Nicotiana tabacum, Datura stramonium, and Solanum lycopersicum) and three new (Solanum melongena, Physalis alkekengi, and Lycium barbarum) host plants. We found that adults preferred to oviposit on S. tuberosum and N. tabacum leaves and the soil around these native host plants over other hosts. Larvae performed well on S. tuberosum and N. tabacum, reaching higher pupa weight and having better survival. Larvae performed poorly on S. melongena, S. lycopersicum, P. alkekengi, D. stramonium, and L. barbarum, with lower pupa weight and lower survival. Solanum tuberosum and N. tabacum had higher leaf soluble proteins than other plants and lower leaf total phenolics than S. lycopersicum, D. stramonium, and L. barbarum. Moreover, carbon content and soluble protein were positively associated with larval survival, while defensive traits (lignin and total phenolics) negatively affected larval survival. These findings provide insights into understanding of biochemical mechanisms of interactions between invasive insects and host plants, indicating the importance of considering plant chemistry when assessing invasive insect host use and damage.

As we know that hydraulic fracturing as a major method has gained great attention in developing the unconventional oil and gas resources in the past decades. Since the unconventional reservoir is very complex and the success of fracturing operation depends largely on the performances of the fracturing fluid, a good fracturing fluid such as a low carbon hydrocarbon non-aqueous fracturing fluid can be a good solution to these problems. A non-aqueous fracturing fluid with good performance was obtained in the presence of main agent aluminum sulfate, aluminum chloride or aluminum nitrate. The reaction time, temperature, material ratio and crosslinking ratio were carefully screened to match the new dialkyl phosphate in a base fluid of n-pentane or n-hexane via cross-linking to prepare a novel type of low carbon hydrocarbon non-aqueous fracturing fluid for unconventional reservoir. This fracturing fluid system performed excellent heat and shearing resistance, and could maintain high viscosity at high temperature (120–167 °C), which could be further proved by the clear structure of microscopic three-dimensional network. Finally, the fracturing fluid could be broken quickly without any residue. It can be seen that such features make it potentially economic, useful and practical as an alternative technology, especially under the condition of water shortage.

Chitosan is a widely distributed recyclable green resource in nature. Because of the particular molecular structure, chitosan derivatives have become an effective way to research environmental friendly corrosion inhibitors for oil and gas well acidizing. In this study, four chitosan derivatives were synthesized and investigated as green corrosion inhibitors for P110 steel in 15% HCl solution in various ways, including weight loss, scanning electron microscopy (SEM), electrochemical measurements (EIS), energy dispersive spectrum (EDS) and molecular dynamic simulations. The experimental results demonstrate that four chitosan inhibitors have an excellent inhibition effect, and there is an obvious negative correlation between the concentration of corrosion inhibitor and the inhibition efficiency. Finally, the erosion effect of the fluid on the corrosion inhibitor layer was studied under different flow velocity conditions and pipeline positions in oil and gas well. The results reveal that the erosion effect of the pipe is proportional to the inlet velocity of the fluid.

Sulfur deposition attracts great attention for the exploration of oil and gas and is considered one of the most important hazardous processes in China, and all over the world. Thus, investigating a sulfur solvent is absolutely necessary and highly desirable in the sour gas reservoir development. In recent years, various sulfur solvents were developed and applied in different oilfields. However, they have disadvantages in their practical applications. In this paper, a solution is proposed to solve the problem and improve the sulfur dissolving ability. Three types of sulfur solvents were prepared, all of which have their own characteristics and advantages in different cases and compared with the existing sulfur solvents under the same conditions. The solubility of Dimethyl disulfide(DMDS)-based sulfur solvent system was up to 202.8 wt% at room temperature and 1020.0 wt% at 90 °C. Amine solvent systems also achieved high sulfur solubility. The solubility of diethylene triamine-ethanolamine solvent system could reach 79.6 wt% at room temperature and 210.0 wt% in 90 °C. It was shown that a more efficient sulfur solvent system can be achieved by remixing with suitable additives. This paper focuses on a preliminary study of optimizing effective sulfur solvents in order to solve the problems caused by sulfur deposition. In the long run, this may revolutionise the process of exploration, transportation and refining of crude oil or natural gas. Microscopic analysis by Scanning Electron Microscope (SEM) was used to facilitate understanding the mechanism of sulfur dissolution in each system and their differences.

As the hydraulic fracturing technologies are not conducive to the stimulation of unconventional reservoirs and too much water was consumed by the conventional hydraulic fracturing fluid, a waterless low hydrocarbon fracturing fluid system was developed as an alternative way in the view of sustainable development and energy boom. It is noteworthy that this novel system was found to exhibit excellent heat and shear resistance, while maintaining high viscosity at high temperature (up to 150 °C). In order to reduce the cost, the low carbon hydrocarbon phosphate gelling agent was prepared via the reaction of triethyl phosphate (TEP), phosphorus pentoxide (P2O5) and single alcohol, which is quite different from the reported phosphates using mixed alcohols. In addition, a ferric-complex cross-linking agent was acquired which contains main agent, complexing agent, phase transfer catalyst (PTC) and crosslinking accelerator of crosslinking agent. The rheology of low-carbon hydrocarbon non-aqueous fracturing fluid system was tested. Furthermore, gel structure could be directly observed by scanning electron microscopy, which could explain its good performance.

Novel surfactants were synthesized and investigated as green corrosion inhibitor for mild steel in 15% HCl solution in various ways including weight loss, electrochemical measurements, scanning kelvin probe (SKP), scanning electron microscope (SEM) and theoretical calculations. The efficiency of the inhibitors against the corrosion of mild steel in the aggressive solution (15% HCl) were evaluated gravimetrically at various temperatures. The corrosion inhibition efficiency (η) has been increased with the increase of the inhibitor concentration, the maximum η achieved was equal to 98.97 at temperature 90 °C. The experiments results reveal that two surfactants were effective corrosion inhibitor, and because of the amphiphilic nature of surfactant molecules, the inhibitors can be adsorbed onto mild steel surface, obeying the Langmuir adsorption isotherm. Finally, Theoretical calculation parameters of quantum chemical calculation and molecular dynamic simulations further showing a definite correlation between the theoretical and experimental results.

We reported a highly effective Pd-catalytic system for the synthesis of diarylbenzenes through Suzuki-type reaction between equal amount of diiodoarenes and arylboronic acids. This preferential oxidative addition resulted in such high selectivity.

A category of gemini surfactants with novel structures were designed and synthesized as thickening agents of clean fracturing fluids in this research. The desired products were characterized by high resolution mass spectrometry (ESI-HRMS) and infrared spectrometry (FT-IR GX). Fluid samples with a formula of 5 wt% of products and 1 wt% of KCl were evaluated. The SEM studies revealed a good network microstructure and obvious viscoelasticity, which is favorable for a proppant suspension. Furthermore, the evaluation of their rheological properties at high temperatures revealed good thermal stabilities of these fluids up to 139 °C, particularly for VES-M (the spacer for the surfactant using methylamine and epoxy chloropropane). Comparative analysis of the rheological properties showed that since long chains of N-substituents in the middle of the molecules could enhance steric hindrance and rigidity, it is unfavorable for molecular entanglement and increases the viscosity of the VES aqueous solution. Proppant-support and gel breaking evaluations were also performed. It can be seen that nearly 100% proppant suspension was observed for 180 min at ambient temperature and complete gel breaking was achieved.

Pd-catalyzed direct oxidative olefination of arenes with olefins via C–H activation is described in the absence of any chelating directing groups. For Pd-catalyzed oxidative coupling between arenes and allyl acetate, it was observed the retention of the leaving group.

Formaldehyde dehydrogenase (FDH) is a member of the zinc-containing medium-chain alcohol dehydrogenase family which oxidizes toxic formaldehyde to formate using NAD(+) as an electron carrier. Three-dimensional structures have been reported for FDHs from several different species. Most FDHs are dependent on glutathione for catalysis, but the enzyme from Pseudomonas putida is an exception. In this structural communication, the recombinant production, crystallization and X-ray structure determination at 2.7 Å resolution of FDH from P. aeruginosa are described. Both the tetrameric assembly and the NAD(+)-binding mode of P. aeruginosa FDH are similar to those of P. putida FDH, which is in good agreement with the high sequence identity (87.97%) between these two proteins. Preliminary enzymatic kinetics studies of P. aeruginosa FDH also revealed a conserved glutathione-independent `ping-pong' mechanism of formaldehyde oxidization.

Herein, we report a new "On-On" strategy based on the assembly and disassembly of fluorescein isothiocyanate nanoparticles (FITC-NPs) for sequential detections of glutathione (GSH) and caspase-3 (Casp3) with a multifunctional fluorescent probe 1. Theoretical investigations revealed the underlying mechanism that satisfactorily explained experimental results of such consecutive enhancements of fluorescence. Using this probe, we also successfully imaged the Casp3 activity in apoptotic cells.

A convenient method for synthesizing α-(1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonyl)methane derivatives, 3 and 4, by the well known Knoevenagel reaction, in one step, is described. The two chromophores are stilbene-type chromophores containing the same D-π-A structures and end-capped with aromatic group as their donors. Measured with femtosecond multipass Ti:sapphire amplifier as irradiation source (pumped by the laser at 800 nm), the two chromophores show efficient two-photon induced orange red fluorescence emission. The experimental results indicate that the numbers of branches of the two chromophores affect their one-photon properties and two-photon up-conversion emission behaviors, and with the increasing numbers of branches, their wavelengths of λabsmax, λspfmax and λtpfmax exhibit bathochromic shifts.

The specific heat of the doped blue bronzes Tl0.3-xKxMoO3(x = 0.06, 0.15) has been measured in the temperature range between 100 and 220 K. Anomalies were observed at 165.7 K and 164.8 K for Tl0.24K0.06MoO3and Tl0.15K0.15MoO3, respectively. The specific heat jump, and the entropy and enthalpy changes associated with the CDW phase transition are estimated. The results suggest that the Peierls phase transition is of second order. By analogy with the behavior of pure Tl0.3-xMoO3, it shows that in the quasi-one-dimensional blue bronze, the perfect order of the interlayer alkali or thallium polyhedral chain plays an important role in the Peierls phase transition.

As a member of zinc-containing medium-chain alcohol dehydrogenase family, formaldehyde dehydrogenase (FDH) can oxidize toxic formaldehyde to less active formate with NAD(+) as a cofactor and exists in both prokaryotes and eukaryotes. Most FDHs are well known to be glutathione-dependent in the catalysis of formaldehyde oxidation, but the enzyme from Pseudomonas putida is an exception, which is independent of glutathione. To identify novel glutathione-independent FDHs from other bacterial strains and facilitate the corresponding structural and enzymatic studies, high-level soluble expression and efficient purification of these enzymes need to be achieved. Here, we present molecular cloning, expression, and purification of the FDH from Pseudomonas aeruginosa, which is a Gram-negative pathogenic bacterium causing opportunistic human infection. The FDH of P. aeruginosa shows high sequence identity (87.97%) with that of P. putida. Our results indicated that coexpression with molecular chaperones GroES, GroEL, and Tig has significantly attenuated inclusion body formation and improved the solubility of the recombinant FDH in Escherichiacoli cells. A purification protocol including three chromatographic steps was also established to isolate the recombinant FDH to homogeneity with a yield of ∼3.2 mg from 1L of cell culture. The recombinant P. aeruginosa FDH was properly folded and biologically functional, as demonstrated by the mass spectrometric, crystallographic, and enzymatic characterizations of the purified proteins.