Natural high-porous diatomaceous-earth based self-floating aerogel for efficient solar steam power generation

The application of solar steam generation in seawater desalination is an effective way to solve the shortage of fresh water resources.At present,many kinds of photothermal conversion materials have been developed and used as evaporators in seawater desalination.However,some evaporators need additional thermal insulation or water supply devices to achieve efficient photothermal conversion.In addition,their complex,time consuming and no scalable preparation process,high cost of raw materials and poor salt resistance hinder the practical application of these evaporator.Owing to its distinctive nanoporous structure,diatomite as fossilized single-cells algae diatoms is a promising natural silica-based material for seawater desalination.They are taken from sea and that makes true sense to use them in the sea.Herein,we report the first example of synthesis robust three-dimensional(3D)natural-diatomite composite by assembling polyaniline nanoparticles covered diatomite into the polyvinyl alcohol pre-treated melamine foam frameworks and demonstrate its application as new evaporator for seawater desalination.The porous framework does not only improve the sunlight scattering efficiency,but also offer large network of channels for water transportation.The inherent mechanism behind salt desalination process involves the absorption of water molecules on the surface of the internal silica micro-nano pores,and evaporation under the heat induced by the polyaniline absorbed sunlight.Meanwhile,the metal ions are segregated by many available pores and channels to achieve the self-desalting effect.The developed evaporator possesses the superiority of multi-stage pore structure,strong hydrophilicity,low thermal conductivity,excellent light absorption,fast water transportation and salt-resistant crystallization as well as good durability.The evaporation rate without an additional device is found to be 1.689 kg m^(-2)h^(-1)under 1-Sun irradiation,and the energy conversion efficiency is as high as 95%.This work creates a platform and develops the prospect of employing green and sustainable natural-diatomite composite evaporator for practical applications of seawater desalination.

Numerical and experimental investigation of quantitative relationship between secondary flow intensity and inviscid blade force in axial compressors

The secondary flow attracts wide concerns in the aeroengine compressors since it has become one of the major loss sources in modern high-performance compressors.But the research about the quantitative relationship between secondary flow and inviscid blade force needs to be more detailed.In this paper,a database of 889 three-dimensional linear cascades was built.An indicator,called Secondary Flow Intensity(SFI),was used to express the loss caused by secondary flow.The quantitative relationship between the SFI and inviscid blade force deterioration was researched.Blade oil flow and Computation Fluid Dynamics(CFD)results of some cascades were also used to cross-validate.Results suggested that all numerical cascade cases can be divided into 3 clusters by the SFI,which are called Clusters A,B and C in the order of the increasing SFI indicator.The corner stall,known as the strong corner separation,only happens when the SFI is high.Both calculations and oil flow experiments show that the SFI would stay at a low level if the vortex core at the endwall surface does not appear.The strong interaction of Kutta condition and endwall cross-flow is considered the dominant mechanism of higher secondary flow losses,rather than the secondary flow penetration depth on the suction surface.In conclusion,the inviscid blade force spanwise deterioration is strongly related to the SFI.The correlation of the SFI and spanwise inviscid blade force deterioration is given in this paper.The correlation could provide a quantitative reference for estimating secondary flow losses in the design.

Static pressure redistribution mechanism of non-axisymmetric endwall based on radial equilibrium

Non-axisymmetric endwall contouring has been proved to be an effective flow control technique in turbomachinery.Several different flow control mechanisms and qualitative design strategies have been proposed.The endwall contouring mechanism based on the flow governing equations is significant for exploring the quantitative design strategies of the nonaxisymmetric endwall contouring.In this paper,the static pressure redistribution mechanism of endwall contouring was explained based on the radial equilibrium equation.A quantified expression of the static pressure redistribution mechanism was proposed.Compressor cascades were simulated using an experimentally validated numerical method to validate the static pressure redistribution mechanism.A geometric parameter named meridional curvature(Cme)is defined to quantify the concave and convex features of the endwall.Results indicate that the contoured endwall changes the streamline curvature,inducing a centrifugal acceleration.Consequently,the radial pressure gradient is reformed to maintain the radial equilibrium.The convex endwall represented by positive Cme increases the radial pressure gradient,decreasing the endwall static pressure,while the concave endwall represented by negative Cme increases the endwall static pressure.The Cme helps to establish the quantified relation between the change in the endwall radial pressure gradient and the endwall geometry.Besides,there is a great correlation between the distributions of the Cme and the change in the endwall static pressure.It can be concluded that the parameter Cme can be considered as a significant parameter to parameterize the endwall surface and to explore the quantitative design strategies of the nonaxisymmetric endwall contouring.

New molecular method to detect denitrifying anaerobic methane oxidation bacteria from different environmental niches

The denitrifying anaerobic methane oxidation is an ecologically important process for reducing the potential methane emission into the atmosphere.The responsible bacterium for this process was Candidatus Methylomirabilis oxyfera belonging to the bacterial phylum of NC10.In this study,a new pair of primers targeting all the five groups of NC10 bacteria was designed to amplify NC10 bacteria from different environmental niches.The results showed that the group A was the dominant NC10 phylum bacteria from the sludges and food waste digestate while in paddy soil samples,group A and group B had nearly the same proportion.Our results also indicated that NC10 bacteria could exist in a high p H environment（pH 9.24）from the food waste treatment facility.The Pearson relationship analysis showed that the p H had a significant positive relationship with the NC10 bacterial diversity（p0.05）.The redundancy analysis further revealed that the p H,volatile solid and nitrite nitrogen were the most important factors in shaping the NC10 bacterial structure（p=0.01）based on the variation inflation factors selection and Monte Carlo test（999 times）.Results of this study extended the existing molecular tools for studying the NC10 bacterial community structures and provided new information on the ecological distributions of NC10 bacteria.

Cyanobacteria-based self-oxygenated photodynamic therapy for anaerobic infection treatment and tissue repair

Photodynamic therapy(PDT)is an important technique to deal with drug-resistant bacterial infections in the post-antibiotic era.However,the hypoxic environment in intractable infections such as refractory keratitis and periodontitis,makes PDT more difficult.In this work,spontaneous oxygen-producing cyanobacteria were used as the carrier of photosensitizer(Ce6),and ultrasmall Cu_(5.4)O nanoparticles(Cu_(5.4)O USNPs)with catalase activity for infection and inflammation elimination and rapid tissue repair(CeCycn-Cu_(5.4)O).The loading of Ce6 and Cu_(5.4)O USNPs onto cyanobacteria surface were confirmed by transmission electron microscopy,nano particle size analyzer,scanning electron microscopy.In vitro sterilization and biofilm removal experiments demonstrated that the restriction of hypoxic environment to PDT was significantly alleviated due to the oxygen production of cyanobacteria.Under laser irradiation,the close transfer of energy photons to oxygen produced by cyanobacteria reduced more than 90% of Ce6 dosages(660 nm,200 mW/cm^(2),2 min).It is worth mentioning that both rapid sterilization through PDT and long-term oxidized free radicals elimination were achieved by adjusting the ratio of Ce6 and Cu_(5.4)O USNPs.Both periodontitis and refractory keratitis animal models proved the excellent self-oxygenation enhanced antibacterial property and promotion of tissue repair.