A Biofouling Resistant Zwitterionic Polysulfone Membrane Prepared by a Dual-Bath Procedure

This study introduces a zwitterionic material to modify polysulfone (PSf) membranes formed by a dual bath procedure, in view of reducing their fouling propensity. The zwitterionic copolymer, derived from a random polymer of styrene and 4-vinylpyrridine and referred to as zP(S-r-4VP), was incorporated to the PSf solution without any supplementary pore-forming additive to study the effect of the sole copolymer on membrane-structuring, chemical, and arising properties. XPS and mapping FT-IR provided evidence of the modification. Macrovoids appeared and then disappeared as the copolymer content increased in the range 1–4 wt%. The copolymer has hydrophilic units and its addition increases the casting solution viscosity. Both effects play an opposite role on transfers, and so on the growth of macrovoids. Biofouling tests demonstrated the efficiency of the copolymer to mitigate biofouling with a reduction in bacterial and blood cell attachment by more than 85%. Filtration tests revealed that the permeability increased by a twofold factor, the flux recovery ratio was augmented from 40% to 63% after water/BSA cycles, and irreversible fouling was reduced by 1/3. Although improvements are needed, these zwitterionic PSf membranes could be used in biomedical applications where resistance to biofouling by cells is a requirement.

Electro-thermo-mechanical modeling of shape memory polymers filled with nano-carbon powder

Generally, adding the electroconductive fillers into the polymer matrix is a popular approach to endow the shape memory polymers (SMPs) with electroconductivity. Therefore, the shape memory effects (SMEs) of thermally induced SMPs can also be triggered by the electrical current. In essence, both the thermally activated and electrically activated SMEs share the same driving mechanism without considering the effect of heat conduction. In the paper, the constitutive model for the thermally induced SMPs filled with nano-carbon powder is briefly introduced. Then, a modified model is developed to characterize the effects of filler, deformation, and moisture on the electrical conductivity for the first time. After developing the correlation of electric field with Joule heat, the simulation is executed to display the free recovery of the shape memory polymer composites (SMPCs) with different filler content. It is found that the recovery ratio decreases with the increase of carbon powders for the SMPCs with filler content above the percolation threshold. Besides, a good recovery ratio can also be achieved through the application of a lower voltage.

Study on Oil-water Two-phase Migration Mechanism of Low Permeability Fractured Core based on the Online NMR Testing

Understanding the dynamic migration mechanism of oil-water two-phase is the key to improve the effect of water injection development in low permeability fractured reservoir. Based on artificial fracturing of core and basic physical parameter testing, the online NMR displacement experiments of cores with different fracture widths are conducted to analyze the oil-water dynamic distribution characteristics and migration mechanisms. The experimental results show that when water breaks through at the outlet, oil volume in the small pores is basically unchanged. In the large pores it decreases to a certain extent, while in the fracture it decreases greatly. When the displacement is over, oil volume in the small pores still changes little, while it decreases greatly in the large pores, and it is almost zero in the fracture. With the decrease of fracture width, the recovery ratio when waterflooding front breaks through and the final recovery ratio after displacement increase gradually. The contribution proportion of recovery ratio in the fracture decreases as a whole, while in the large pores it increases gradually, and in the small pores it decreases slightly. The research results lay a foundation for the optimal design of fracture parameters and the adjustment of water injection development technology policy in low permeability fractured reservoir.

Applicability of Clinical Decision Support in Management among Patients Undergoing Cardiac Surgery in Intensive Care Unit: A Systematic Review

Advances achieved in recent decades regarding cardiac surgery have revealed a new risk that goes beyond surgeons’ dexterity; post-operative hours are crucial in these patients and are usually spent at intensive care units (ICUs), where they need to be continuously monitored to adjust the treatments. Clinical decision support systems (CDSS) have been developed to take this real-time information and provide clinical suggestions to physicians, so as to reduce medical errors and increase patient recovery ratio. In this review, an initial total of 666 papers were considered, finishing with 23 of them after the researchers’ filter, which included the deletion of duplications and exclusion if the title and abstract were not of real interest. The review of these papers concludes the applicability and extends the CDSS offer to both doctors and patients. Better prognosis and recovery rate are achieved by using this technology, which also has high acceptance among most physicians. However, despite the evidence that well-designed CDSS are effective, they still need to be refined to offer the best assistance as possible, which may still take time, despite the promising models that have already been applied in real ICUs.

Research on Minimum Miscible Pressure Between Crude Oil and Supercritical Carbon Dioxide System in Ultra-Low Permeability Reservoir by the Long-Slim-Tube Experiment Method

Carbon dioxide (CO2) injection has become an important technology to enhance oil recovery in ultra-low permeability reservoirs. Compared with other CO2 flooding technologies, CO2 miscible flooding has a better development effect, and the minimum miscible pressure (MMP) is a key parameter to realize miscible flooding. Therefore, it is very important to accurately predict the MMP. The prediction methods of MMP generally include laboratory experiment method and theoretical calculation method. In this study, a long-slim-tube displacement experiment method was used to determine the MMP in the study area, and the experimental temperature and pressure were consistent with those under reservoir conditions. The research results show that the recovery ratio increased gradually with the increase of experimental pressure, but the increase amplitude gradually decreased. According to the relation curve between crude oil recovery ratio and experimental displacement pressure, when the experimental pressure was larger than 29.6 MPa, the recovery ratio did not increase significantly with the increase of displacement pressure, which indicates that the interfacial tension between crude oil and CO2 disappeared under this pressure and they reached a miscible state. It is speculated that the MMP between crude oil and CO2 system in the study area predicted by the long-slim-tube displacement experiment method was 29.6 MPa. The results of this study help to realize miscible flooding in ultra-low permeability reservoirs and thus enhance oil recovery.

Designing of a novel polyvinylidene fluoride/TiO2/UiO-66-NH2 membrane with photocatalytic antifouling properties using modified zirconium-based metal-organic framework

Novel polyvinylidene fluoride/TiO2/UiO-66-NH2 (PVDF/TiUN) membranes were produced by the delay phase separation method via introducing the TiO2/UiO-66-NH2 (TiUN) nanocomposite into PVDF casting solution. Interconnection of TiO2 and UiO-66-NH2 improved photocatalysis capacity and endowed PVDF/TiUN membranes with self-cleaning capability. Quantitative measurements showed that, firstly, PVDF/TiUN membranes exhibited improved photodegradation kinetics and efficiency (up to 88.1%) to Rhodamine B (RhB). Secondly, the performances of bovine serum albumin (BSA) rejection and permeation of PVDF/TiUN membranes outperformed those of other check samples, indicating enhanced hydrophilicity. Thirdly, rejection rate of BSA reached to breathtaking 98.14% and flux recovery ratio (FRR) of BSA reached breathtaking 95.37%. Thus, given their excellent anti-contamination property and separation performance, the PVDF/TiUN membrane is very likely to be a novel water treatment membrane.

Novel High Flux Poly(m-phenylene isophtalamide)/TiO2 Membranes for Ultrafiltration with Enhanced Antifouling Performance

Wide application of ultrafiltration in different industrial fields requires the development of new membranes with tailored properties and good antifouling stability. This study is devoted to the improvement of ultrafiltration properties of poly(m-phenylene isophtalamide) (PA) membranes by modification with titanium oxide (TiO2) particles. The introduction of TiO2 particles improved membrane separation performance and increased antifouling stability and cleaning ability under UV irradiation. The developed membranes were characterized by scanning electron and atomic force microscopy methods, the measurements of water contact angle, and total porosimetry. The transport properties of the PA and PA/TiO2 membranes were tested in ultrafiltration of industrially important feeds: coolant lubricant (cutting fluid) emulsion (5 wt.% in water) and bovine serum albumin (BSA) solution (0.5 wt.%). The PA/TiO2 (0.3 wt.%) membrane was found to possess optimal transport characteristics in ultrafiltration of coolant lubricant emulsion due to the highest pure water and coolant lubricant fluxes (1146 and 32 L/(m2 h), respectively), rejection coefficient (100%), and flux recovery ratio (84%). Furthermore, this membrane featured improved ability of surface contamination degradation after UV irradiation in prolonged ultrafiltration of BSA, demonstrating a high flux recovery ratio (89–94%).

Optimization of Caving Technology in an Extrathick Seam with Longwall Top Coal Caving Mining

The optimization of top coal caving technology is an efficient method to improve the recovery ratio in longwall top coal caving (LTCC). In extrathick coal seams, the conventional single-opening sequential caving technology (SOSCT) shows the following problems: low recovery ratio, high rock mixed ratio, and poor drawing balance. For these problems, this research verifies the applicability of multiopening caving technology (MOCT) in extrathick coal seams theoretically. However, different drawing sequences have a great effect on the drawing mechanism. Based on the progressive drawing sequence of cluster-group-support, this paper firstly proposes a systematic naming method for the top coal caving technology. Furthermore, an independent cluster-group caving technology (ICGCT) is given, meaning that all supports are divided into several clusters, a cluster is divided into several groups, and clusters extract top coal in positive order while groups are in reverse order in the drawing process. By establishing an experimental model by the discrete element method PFC2D, the drawing mechanism is investigated under different caving technologies. The results show that ICGCT significantly improves the recovery ratio of the panel and mainly increases the drawing volume of top coal in the middle and upper end of the panel. The shape of the top coal boundary reflects the drawing efficiency. Due to the effect of drawing sequence in ICGCT, the generation and disappearance processes of coal ridge greatly decrease the residual top coal in the middle of the panel. The drawing body shape has a direct influence on the recovery ratio. Multiple complete drawing bodies exist in ICGCT, and the dispersion coefficient of drawing volume changes periodically in the range of 0.5–1.7, which is conducive to the management of drawing processes. In addition, discussing ICGCT and the dependent cluster-group caving technology (DCGCT), it is found that the recovery ratio of DCGCT has a slight increase, which enlarges the maximum drawing range of top coal at both panel ends, shortening the total drawing time of the panel. In summary, ICGCT provides a new approach for improving the recovery ratio and drawing balance in LTCC with an extrathick coal seam.