Biofouling on heat exchange devices can decrease heat transfer efficiency, corrode materials, and even lead to safety accidents. Most heat exchange devices are made of carbon steel that efficiently ...produces biofouling. However, in this paper, a nickel–phosphorus–reduced graphene oxide (Ni–P–rGO) coating was prepared on carbon steel by electroless plating to investigate the properties of iron bacteria biofouling. The surface coating was analyzed via scanning electron microscopy and Raman spectroscopy. After the carbon steel and the Ni–P–rGO coating were immersed into an iron bacteria solution for 120 h, the weight of the iron bacteria biofouling on the Ni–P–rGO coating sharply decreased when compared with the carbon steel. We can conclude that the concentration of graphene can affect the weight of iron bacteria biofouling. We also found that the coating solution with 40 mg/L of graphene performed the best in inhibiting biofouling by decreasing the weight of the biofouling by 97.2% compared to carbon steel.
CaF2 raw powders were synthesized by the chemical precipitation technique, and CaF2 ceramics with LiF sintering additives were fabricated by the hot-pressing (HP) sintering technique. The effects of ...LiF sintering additives on the optical transparency, microstructure and microhardness of CaF2 ceramics were investigated. The CaF2 ceramic with 0.05 wt% LiF exhibiting the best transparency, and the transmittance at 500 nm and 1800 nm are 71.5% and 87.8%, respectively. The average grain size of CaF2 ceramics increases with rising the amount of LiF from 0 to 1 wt%, while, the Vickers hardness (Hv) decreases. The average grain size, Hv, and fracture toughness (KIC) for the CaF2 ceramic with 0.05 wt% LiF are 85.6 ± 6.2 μm, 2.24 ± 0.06 GPa, and 0.11 ± 0.02 MPa m1/2, respectively.
•CaF2 transparent ceramic were fabricated with LiF additive by HP sintering.•The effect of LiF additive on properties of ceramics was systematic studied.•The highest transmittance reached 71.5% at 500 nm and 87.8% at 1800 nm.•Average grain sizes of ceramics increases with rising the LiF adding levels.
Microplastics (MPs) are new environmental pollutants and have received widespread attention in recent years, but the toxicity of the MPs remains to be fully elucidated. To explore the effect of MPs ...on hepatotoxicity in mice and unravel the mechanism of pyroptosis and ferroptosis in the process of liver injury, we treated mice with 5.0 μm polypropylene microplastics (MPs) at 0.1, 0.5 and 1 mg/mL for 4 weeks. Results revealed that MPs could damage liver structure and function with broken and reduced mitochondrial cristae, as well as increased levels of aspartate minotransferase (AST), alanine aminotransferase (ALT), AST/ALT, alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). Treatment with MPs resulted in pyroptosis as evidenced by increasing expressions of interleukin IL-1β, IL-18. Additionally, MPs were shown to induce the NOD-like receptor protein 3 (NLRP3) inflammasomes and apoptosis associated speck-like protein (ASC) containing a caspase recruitment domain activation in liver tissue, enabling activation of Caspase-1-dependent signaling pathway induced by inflammatory stimuli resulting from oxidative stress. In addition, the increase of malondialdehyde (MDA) and decrease of glutathione (GSH) and superoxide dismutase (SOD) in the liver indicated that MPs could induce oxidative damage. Moreover, MPs induced lipid peroxidation in the liver of mice could activate the expression of ferroptosis related proteins, including iron metabolism, such as transferrin receptor (TFRC) was active but ferritin heavy chain 1 (FTH1) was inhibited; amino acid metabolism, such as XCT system and glutathione peroxidase 4 (GPX4) were inhibited; lipid metabolism, such as acyl-CoA synthetase long-chain family member 4 (ACSL4) was inhibited. Collectively, these findings evidenced that pyroptosis and ferroptosis occurred in MPs-induced liver injury accompanied by intense oxidative stress and inflammation.
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•Mice were exposed to polystyrene microplastics, which can accumulate in the liver and induce liver injury.•Exposure to polystyrene microplastics can cause liver inflammation and oxidative stress.•Activation of pyroptosis and ferroptosis is involved in the hepatotoxicity induced by polystyrene microplastics.
•Heat transfer enhancement in a rectangular channel with five novel types of vortex generators (VGs) was investigated.•The half-cylinder VGs is the best vortex generator of low resistance and high ...efficient.•The effect of arrangement, length, radius and spacing of the half-cylinder VGs were presented.•The simulated results were validated based on the experimental date and the formula data.
The vortex generators (VGs) are among the most popular actuators for the heat transfer enhancement of heat exchangers. Using pure water as the working fluid, the characteristics of heat transfer and flow resistance in a rectangular channel with novel types of VGs were studied numerically at the Reynolds number range of Re=8900–29,900. Five types of VGs with the same frontal area were used in the present study and the corresponding mechanism of heat transfer was analyzed. The heat transfer enhancement and flow resistance were examined by using the dimensionless parameters j/j0, f/f0, R=(j/j0)/(f/f0), and R∗=Nuc/Nu0. The results revealed that, when the thermohydraulic performance factor R and Performance Evaluation Criterion R∗ were considered as the comprehensive evaluation criteria, the half-cylinder VG was the best. Then the effects of arrangement, length, radius, and spacing of the half-cylinder VGs on the heat transfer and flow resistance were investigated. When the half-cylinder VGs were arranged along the side-lined row, the thermohydraulic performance factor R was the largest. With the increase in the generator length, the thermohydraulic performance factor R increased at first and then decreased, and exhibited the maximum value at A/B=0.50. With the increase in the radius and decrease of the spacing, the thermohydraulic performance factor R decreased.
Salt basins along the passive continental margin of West Africa are becoming one of the most attractive areas for hydrocarbon exploration. The oil and gas discovered recently are related to salt ...structures. The salt structures are widespread in Anglo-Cameroon, the thickness of salt is up to 1 500 m and the average width is 300 km. These basins can be divided into two parts in horizontal direction: extensional zone and compressional zone, which extend 100–150 km and 100–200 km respectively. The extensional zone includes sealed titled zone, growth fault zone and diapir zone, and is characterized by tilted block, rollover structure and turtle structure anticline. The compressional zone is characterized by salt sheet, salt tongue, thrust fault and small folds. Oil and gas are distributed in both zones, oil and gas reserves in the extensional zone are a little larger than reserves in the compressional zone. Several types of salt related traps can be recognized, such as salt anticline, salt diapir and fault related trap, unconformity and structural-lithologic traps. Salt anticlines are the most potential exploration targets.
The high quality of different holmium doping concentration calcium fluoride (Ho: CaF2) transparent ceramics were fabricated by hot-pressing method, which average transmittance reached to 83% at ...1200 nm. The effect of Ho3+ concentrations on structural and spectroscopic properties of Ho: CaF2 transparent ceramics were investigated. With the increase of the Ho3+ ions doping concentration, the grain size of nanopowders decreased and the grain size of ceramics decreased first and then increased. The absorption coefficient of the Ho: CaF2 increased with the increase of doping concentrations. Emission and absorption cross sections of the 5I7 energy level of Ho3+ in CaF2 transparent ceramics were investigated. A strong intensity of emission peak at 2030 nm was observed, the fluorescence lifetime at 2030 nm was also investigated which indicating that Ho:CaF2 transparent ceramic is a potential candidate for 2.0 μm laser emission materials.
•Ho3+: CaF2 transparent ceramics with different concentration were fabricated.•Phase composition and morphologies of Ho3+: CaF2 nanopowders were measured.•The spectroscopic properties of Ho3+:CaF2 transparent ceramics were investigated.•Results indicated Ho3+: CaF2 transparent ceramic is a feasible laser gain medium.
Plate heat exchanger (PHE) has been widely used in energy transport fields for its high efficiency and compact structure. However, fouling is an intractable issue which reduces heat transfer ...efficiency and increases pressure drop. In this study, an experimental investigation on composite fouling characteristics of Ni-P-PTFE nanocomposite coating in corrugated PHE was conducted to evaluate the anti-fouling performance of this modified surface. The nanocomposite coating was prepared based on the stainless steel 304 plates through the electroless composite plating method. Clean tests and accelerated composite fouling tests were carried out, and the heat transfer and pressure drop performance of both the uncoated and coated plates was analyzed. Moreover, micro-structure of the surfaces and fouling deposits was mapped by scanning electron microscope. Compared to uncoated plates, the Ni-P-PTFE coated plates showed lower pressure drop by up to 15.8% and lower heat transfer performance by up to 17.6% at clean state. The smooth coating decreased the friction loss of the flow, while slightly increased the heat conduction resistance. The Ni-P-PTFE coated plates showed a significant anti-fouling performance, which decreased the fouling's weight by 20.4% and the asymptotic fouling resistance by 28.2%, meanwhile reduced the pressure drop increment by 44.8%.
Ytterbium-doped strontium fluoride (Yb: SrF2) nanopowders with different amounts of Yb3+ were synthesized by a co-precipitation method. XRD and FE-SEM measurements were used to characterize the phase ...composition and morphologies of these nanopowders. The Yb: SrF2 nanopowders doped with 1–5 at.% Yb3+ showed the same phase as pure SrF2, with a mean particle size of 20 nm. Transparent Yb: SrF2 ceramics were fabricated by hot-pressing the nanopowders, and the transmittance of 1 at.% Yb: SrF2 with a thickness of 2 mm was 85% at 1200 nm. The absorption spectra, luminescence spectra, and luminescence decays of the ceramics were also obtained. As the Yb3+ doping amount increased, the absorption and emission intensities also increased, indicating the absence of a concentration quenching effect in the Yb: SrF2 ceramics. However, the decay lifetimes decreased with increasing Yb3+ content, and 1–5% Yb: SrF2 transparent ceramics had decay lifetimes of 4.58, 3.48, 3.22, and 3.19 ms, respectively.
•Yb3+: SrF2 transparent ceramics with different concentrations were fabricated.•Phase composition and morphologies of Yb3+: SrF2 nanopowders were measured.•The spectroscopic properties of Yb3+: SrF2 transparent ceramics were investigated.
Pr3+, Gd3+ co‐doped SrF2 transparent ceramic, as the potential material for visible luminescent applications, was prepared by hot‐pressing of precursor nanopowders. The microstructure, phase ...compositions, and in‐line transmittance, as well as the photoluminescence properties were investigated systematically. Highly optical quality Pr,Gd:SrF2 transparent ceramic with nearly pore‐free microstructure was obtained at 800°C for 1.5 hours. The average in‐line transmittance of the x at.% Pr, 6 at.% Gd:SrF2 (x = 0.2, 0.5, 1.0, 2.0) transparent ceramics reached to 87.3 % in the infrared region. The photoluminescence spectra presented intense visible light emissions under the excitation of 444 nm, the main intrinsic emission bands located at 483 and 605 nm, which were attributed to the transitions of Pr3+: 3P0 → 3H4 and 1D2 → 3H4, respectively. With the co‐doping of Gd3+ ions, the emission intensity of the Pr:SrF2 transparent ceramic was greatly enhanced. All the emission bands of x at.% Pr, 6 at.% Gd:SrF2 transparent ceramics exhibited the highest luminescence intensity with the 1.0 at.% Pr3+ doping concentrations, whereas the lifetimes decreased dramatically with the Pr3+ doping contents increasing from 0.2 to 2.0 at.% due to its intense concentration quenching effect. The 1 at.% Pr, 6 at.% Gd:SrF2 transparent ceramic is a promising material for visible luminescent device applications.
Transmittance curves and visible photoluminescence spectra of x at.% Pr, 6 at.% Gd:SrF (x=0.2, 0.5, 1.0, 2.0) transparent ceramics.
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