The precipitation and deposition of asphaltenes often cause great troubles to the recovery and transportation of crude oil. Adding polymer inhibitors is an effective approach to prevent asphaltenes from clogging. In this study, maleic anhydrideco-octadecene copolymers with imidazolyl, phenyl, and pyridyl pendants were synthesized. The inhibition behaviors of two extracted asphaltenes in the presence of these copolymers were investigated, which were also identified by the rheological tests of the heavy crude oil sample. The chemical structure of both asphaltenes was analyzed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), elemental analysis, and time-of-flight (TOF) spectrometry. Both asphaltenes A and B have a high aromaticity and low H/C. However, asphaltene B has a much higher aromaticity and polarity than that of asphaltene A. Ultraviolet−visible spectroscopy, turbidity meter, and dynamic light scattering (DLS) were employed to determine the precipitation behaviors of asphaltenes in the absence and presence of copolymers. The influence of intrinsic properties of asphaltenes, polymer concentration, and aromatic group grafting ratio on asphaltene precipitation were also compared. It is found that the initial precipitation point (IPP) of both asphaltenes is increased most by the copolymer containing 2-aminopyridine (PMO-2-P), while the copolymer containing N-(3-aminopropyl)imidazole (PMO-I) shows the worst inhibition performance. It is because that pyridine group has a stronger adsorption capacity with asphaltene than the imidazole group. The effect of various functional groups in copolymers on inhibiting asphaltene precipitation conforms to the following sequence: 2-aminopyridine > aniline > 4aminopyridine > N-(3-aminopropyl)imidazole. It is also found that high polymer concentration and grafting ratio are beneficial to inhibit the asphaltene precipitation. As a result of the π−π conjugation and hydrogen-bonding attractions between the aromatic groups in the copolymers and the asphaltenes, the polymers can be stably adsorbed onto the surface of the asphaltenes and prevent their aggregation.

A high content of asphaltene and wax in crude oil leads to difficulties in the recovery and transportation of crude oil due to the precipitation of asphaltenes and the deposition of waxes. Comb-like polymers were found to be capable of inhibiting the aggregation of asphaltenes and crystallization of waxes. In this work, comb-like bipolymers of α-olefins/ultra-long chain (C18, C22 and C28) alkyl acrylate were synthesized and characterized by FT-IR and 1H NMR spectra. The results show that, for a model oil containing asphaltene, the initial precipitation point (IPP) of asphaltene was prolonged by UV, and the asphaltene particle size was reduced after adding the biopolymers, as revealed by dynamitic light scattering (DLS). The bipolymer containing the longer alkyl chain had a better asphaltene inhibition effect. However, DSC and rheological results show that the wax appearance temperature (WAT) of the typical high asphaltene and high wax content of crude oil was obviously reduced by adding bipolymers with shorter alkyl chains. The bipolymer (TDA2024-22) with a mediate alkyl chain (C22) reduced the viscosity and thixotropy of the crude oil by a much larger margin than others. Compared with the previously synthesized bipolymer with phenyl pendant (PDV-A-18), TDA2024-22 exhibited a better performance. Therefore, bipolymers with appropriate alkyl side chains can act as not only the asphaltene inhibitors but also wax inhibitors for high asphaltene and wax content of crude oil, which has great potential applications in the oil fields.

Background: Studies have found that autophagy could promote the clearance of Aβ. To promote and maintain the occurrence of autophagy in Alzheimer's disease (AD) might be a potential way to reduce neuronal loss and improve the learning and memory of AD. Objective: To investigate the possible mechanisms of Yishen Huazhuo Decoction (YHD) against AD model. Methods: Forty 7-month-old male SAMP8 mice were randomly divided into model (P8) group and YHD group, 20 in each group, with 20 SAMR1 mice as control (R1) group. All mice were intragastrically administered for 4 weeks, YHD at the dosage of 6.24g/kg for YHD group, and distilled water for P8 group and R1 group. Morris water maze (MWM) test, Nissl’s staining, TEM, TUNEL staining, immunofluorescence double staining, and western blot analysis were applied to learning and memory, structure and ultrastructure of neurons, autophagosome, apoptosis index, Aβ, LAMP1, and autophagy related proteins. Results: The escape latency time of YHD group was significantly shorter on the 4th and 5th day during MWM test than those in P8 group (P=0.011, 0.008<0.05), and the number of crossing platform in YHD group increased significantly (P=0.02<0.05). Nissl’s staining showed that the number of neurons in YHD group increased significantly (P<0.0001). TEM showed in YHD group, the nucleus of neurons was slightly irregular, with slightly reduced organelles, partially fused and blurred cristae and membrane of mitochondria. The apoptosis index of YHD group showed a decreasing trend, without statistically significant difference (P=0.093>0.05), while Caspase3 expression in YHD group was significantly lower (P=0.044<0.05). YHD could promote the clearance of Aβ1-42 protein, improve the expression of Beclin-1 and p-Bcl2 proteins, reduce mTOR and p62 proteins. Conclusions: YHD could induce autophagy initiation, increase the formation of autophagosomes and autolysosome, promote the degradation of autophagy substrates, thereby to regulate autophagy, thereby to promote the clearance of Aβ1-42 to improve memory impairment in SAMP8 mice.