Asphaltene Inhibition and Flow Improvement of Crude Oil with a High Content of Asphaltene and Wax by Polymers Bearing Ultra-Long Side Chain

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.

Endovascular treatment for acute ischemic stroke in patients with versus without atrial fibrillation: a matched-control study

Background and objective The effect of atrial fibrillation (AF) on outcomes of endovascular treatment (EVT) for acute ischemic stroke (AIS) is controversial. This study aimed to investigate the association of AF with outcomes after EVT in AIS patients. Methods Subjects were selected from ANGEL-ACT registry (Endovascular Treatment Key Technique and Emergency Work Flow Improvement of Acute Ischemic Stroke) - a prospective consecutive cohort of AIS patients undergoing EVT at 111 hospitals in China between November 2017 and March 2019, and then grouped according to having a history of AF or not. After 1:1 propensity score matching, the outcome measures including the 90-day modified Rankin Scale (mRS) score, successful recanalization after final attempt, symptomatic intracranial hemorrhage (ICH) within 24 h, and death within 90 days were compared. Results A total of 1755 patients, 550 with AF and 1205 without AF, were included. Among 407 pairs of patients identified after matching, no significant differences were found in the mRS score (median: 3 vs. 3 points; P = 0.29), successful recanalization (87.2 vs. 85.3%; P = 0.42), symptomatic ICH (9. 4 vs. 9.1%; P = 0.86) and death (16.3 vs. 18.4%; P = 0.44) between patients with and without AF. Conclusion The findings of this matched-control study show comparable outcomes of EVT in Chinese AIS patients with and without AF, which do not support withholding EVT in patients with both AIS and AF. Trial registration NCT03370939 First registration date: 28/09/2017 First posted date: 13/12/2017

Synthesis and characterization of alkyl-methacrylate-maleic anhydride copolymer for use as a biodiesel flow improver

Methacrylic acid was esterified with four alcohols: 1-decanol, 1-dodecanol, 1-tetradecanol, and 1-cetanol. Afterwards, the obtained monomers were copolymerized with maleic anhydride. The synthesized monomers and copolymers were characterized by 1H-NMR (Nuclear magnetic resonance) and Fourier transform infrared (FTIR) spectroscopy. The ability of the obtained copolymers to reduce the pour point of waste cooking oil-based biodiesel was investigated. The results showed that the polymer additive with the alkyl chain C14H29- demonstrated the best flow improvement performance. At a concentration of 1000 ppm, this polymer additive reduced the pour point of waste cooking oil-based biodiesel from 12 to 5oC.In this study,the effect of alkyl chain length, molecular weight, as well as the concentration of the additives on the pour point of biodiesel was also discussed.

Evaluation of Cashew Nut Shell Liquid Borate Ester as Pour Point Depressant for Flow Assurance of Waxy Crude Oil

The development of chemical solutions to wax problems by modifying renewable natural products is an innovative response to the need for cheaper, eco-friendly pour point depressants for waxy crude oil flow improvement. Natural cashew-nut shell liquid (CNSL) was extracted from shells of Anacardium occidentale and derivatized into the borate ester. Pour point of oil doped with 500ppm CNSL borate ester was reduced by -24oC. The effect of borate ester addition on wax morphology was studied by cross-polarized microscopy. Analysis of micrographs using ImageJ software showed a decrease in Feret diameter, aspect ratio, and boundary fractal dimension of wax crystals in doped oil and increased crystal circularity and solidity, indicating the evolution of smaller, rounder, regular structures with smoother, even surfaces. At 10oC, oil shear stress and dynamic viscosity were reduced by 27.6% and 24.6%, respectively. Pour point depressant and flow improvement effects of additive were related to changes in crystal morphology.

Ambulance waiting and associated work flow improvement strategies: a pilot study to improve door-in-door-out time for thrombectomy patients in a primary stroke center

BackgroundRapid access to thrombectomy for patients with large vessel occlusion (LVO) acute ischemic stroke (AIS) is critical for improving outcome. A major challenge for the ‘drip and ship’ model is reducing the door-in-door-out time (DIDO). We propose a new protocol with the aim of reducing DIDO, without adversely affecting emergency service usage time.MethodsConsecutive patients with suspected LVO AIS admitted to a Primary Stroke Center (PSC) from October 2018 to January 2021 were included. On arrival, the ambulance crew remained with the patient. Following immediate clinical and radiological evaluation, patients were transferred to the Comprehensive Stroke Center (CSC) by the same waiting crew. Key time metrics were collected and compared with historical data prior to the new protocol.Results27 patients had an LVO amenable for mechanical thrombectomy during the time period. There was a significant reduction in the DIDO times compared with the historical group (median 45 min vs 96 min; p<0.0001). There was no significant difference in ambulance usage time between the two time periods (median 53 min vs 45 min; p=0.530). There was an increase in ambulance usage time in FAST-positive patients not for transfer in the pilot group compared with FAST-positive patients not for transfer in the historical group (27 min vs 58 min; p<0.001). In addition, door-to-needle times (24 min vs 40 min; p=0.018) and door-to-CT times (11 min vs 25 min; p<0.0001) improved between the two groups.ConclusionOur data show a significant reduction in the DIDO for patients transferred for thrombectomy, with no adverse effects on ambulance usage time.

Improving the effectiveness of the skin integrity restoring after deep burns by platelet-enriched plasma application

Objective. To study the effectiveness of platelet-enriched plasma application in patients with deep burns at the stage of wounds preparation for autodermoplasty. Materials and methods. The study was performed on 23 patients with burns IIA, IIB and III degrees taking 25 - 40% of the body surface. Comprehensive local treatment of patients of the main group included injection of platelet-enriched plasma at the stage of preparation of postoperative wounds for autodermoplasty. In patients of the control group, local treatment was limited by dressings with antiseptic solution. Examination of patients included visual inspection of the damaged area, microbiological examination of wound contents and histological examination of damaged tissues. Results. Applying the suggested method of burn wounds local treatment resulted in reducing time of wounds preparation for closure by autologous skin grafts, reducing of their healing period, decreasing of tissues inflammatory activity, blood flow improvement, and stimulating processes of tissue granulation, proliferation, epithelialization. Conclusions. The application of the autologous platelet-enriched plasma can be considered as an effective biotechnology that can increase the effectiveness of the skin integrity restoring in patients with burns.