Characterization of stress corrosion crack growth of 304 stainless steel by electrochemical noise and scanning Kelvin probe

The fatigue pre-cracking 304 stainless steel (SS) specimens with lengths of 1.002 mm (L-crack) and 0.575 mm (S-crack) were prepared. Their corrosion behavior was studied by electrochemical noise (EN) in 4 mol/L NaCl + 0.01 mol/L Na2S2O3 solution under slow-strain-rate-testing (SSRT) conditions. Moreover, the characteristics of L-crack's surface morphology and potential distribution with scanning Kelvin probe (SKP) before and after SSRT were also discussed. Compared with S-crack, L-crack is propagated and the features of crack propagation can be obtained. After propagation, the noise amplitudes increase with increasing stress and accelerating corrosion, the white noises at low and high frequencies (WL and WH) of the later stage are one order of magnitude larger than that at early stage in the current power spectral densities (PSDs). The potential PSDs also increase, but WH disappears. In addition, the crack propagation can be demonstrated according to variation of probability distribution, surface morphology and potential distribution.

Effects of Concentration and Freeze-Thaw on the First Hydration Shell Structure of Zn^(2+) Ions

To investigate the effects of salt concentration and freeze-thaw (FT) on the first hydration shell of Zn2+ ions in Zn(NO_3)_2 aqueous solutions, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to examine Zn K-edge EXAFS spectra of Zn(NO_3)_2 aqueous solutions with various concentrations before and after FT treatment. The influences of salt concentration and freeze-thaw on the structural parameters of the first hydration shell of Zn2+ ions, including hydration number, Zn-O distance and thermal disorder, were analyzed. The results show that Zn2+ ions have 3.2―6.8 nearest oxygen neighbors with the Zn-O distance being 0.202―0.207 nm. In highly concen-trated solutions, Zn2+ ions are hydrated with four water molecules in a tetrahedral form. The dilution of Zn(NO_3)_2 aqueous solutions increases the number of water molecules in the first hydration shell of Zn2+ ions to six with their octahedral arrangement. Both the hydration number in the first hydration shell of Zn2+ ions and the degree of thermal disorder increase when the FT treatment is operated in Zn(NO_3)_2 aqueous solutions.

Comparable Studies of Adsorption and Magnetic Properties of Ferrite MnFe_2O_4 Nanoparticles,Porous Bulks and Nanowires

The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic properties and adsorption properties of these obtained ferrites with different morphologies were studied contrastively.Results show that the obtained samples exhibit ferromagnetic properties.This realizes convenient magnetic separation from solution when they are used in the treatment of organic dyes wastewater.However,the contrastive studies show that the saturation magnetizations（Ms） of MnFe2O4 with different morphologies are different and the Ms follows the order：Ms（porous）〈Ms（nanoparticles）〈Ms（nanowires）.In addition,the adsorptions of methylene blue（MB） onto these ferrites depend on ferrites＇ morphologies seriously.The adsorption rate of MB on the porous MnFe2O4 is much higher than those onto the other two samples because the porous structure can provide high efficient mass transport through the pores.

The Stady of Legislation on the Utilization of Domestic Sea Water

The contradiction between shortage of water resource and lack of legislation for using seawater as domestic water was revealed. We started our work from present situation of legislation for using seawater as domestic water. Necessity and feasibility of legislation for using seawater as domestic water were explored which contribute to the healthy development of domestic seawater industry.

Recent Advances in Genetic Engineering of Microalgae

Metsbolites generated by microalgac cell metabolism have practical application value in the fields of medicine, food, feed and energy. At present, with the development of genetic engineering techniques and continuous reduction in gene sequencing costs, some micrcalgal genomes have been successively published, which enables specific genetic modification of microalgae according to human＇s demand and provides broad application prospects. In this paper, different mediating systems and emerging genome editing techniques were summarized, which laid the foundation for the application of genetic engineering methods for microalgae.

Chemical oxidation of arsenic in the environment and its application in remediation: A mini review

Arsenic(As)contamination in soil and water poses a serious threat to the ecosystem health and human beings,and is of widespread concern.The main As species found in soil and water are arsenite As(Ⅲ)and arsenate As(V).Because As(Ⅲ)is more toxic and often more mobile than As(Ⅴ),many remediation strategies aim to oxidize As(Ⅲ)to As(Ⅴ).In the environment,the reduction of As(Ⅴ)under anaerobic conditions is mainly mediated by microorganisms,but the oxidation of As(Ⅲ)under aerobic conditions can be mediated primarily by chemical processes.This article first reviews the existing knowledge on chemical oxidation of As(Ⅲ)in the environment,with an emphasis on the roles of iron(Fe)and manganese(Mn)oxides.The application of Fe and Mn oxides for the remediation of As-contaminated soil and water is then summarized.The oxidation of As(Ⅲ)by oxygen is very slow in the absence of catalysts.Many Mn oxides,on the other hand,can efficiently oxidize As(Ⅲ).Although the oxidation of As(Ⅲ)by Fe(Ⅲ)is also slow,this process can be accelerated by light or Fe(Ⅱ).Iron and Mn oxides are widely used for the remediation of As-contaminated soil and water,with Fe oxides generally acting as absorbents while Mn oxides as oxidants.To better understand and regulate As transformation and transport in the environment,further study is needed on the mechanisms and influencing factors of As(Ⅲ)oxidation by Fe and Mn oxides,and the development of innovative methods and materials based on Fe and Mn oxides are desired.

Surface modification of mesoporous silica nanoparticle with 4-triethoxysilylaniline to enhance seawater desalination properties of thin-film nanocomposite reverse osmosis membranes

Mesoporous silica nanoparticles(MSN),with higher water permeability than NaA zeolite,were used to fabricate thin-film nanocomposite(TFN)reverse osmosis(RO)membranes.However,only aminoalkyl-modified MSN and low-pressure(less than 2.1 MPa)RO membrane were investigated.In this study,aminophenyl-modified MSN(AMSN)were synthesized and used to fabricate high-pressure(5.52 MPa)RO membranes.With the increasing of AMSN dosage,the crosslinking degree of the aromatic polyamide decreased,while the hydrophilicity of the membranes increased.The membrane morphology was maintained to show a ridge-and-valley structure,with only a slight increase in membrane surface roughness.At the optimum conditions(AMSN dosage of 0.25 g/L),when compared with the pure polyamide RO membrane,the water flux of the TFN RO membrane(55.67 L/m^2/h)was increased by about 21.6%,while NaCl rejection(98.97%)was slightly decreased by only 0.29%.However,the water flux of the membranes was much lower than expected.We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.

Preparation of reverse osmosis membrane with high permselectivity and anti-biofouling properties for desalination

High performance is essential for the polyamide(PA)reverse osmosis(RO)membranes during the desalination process.Herein,RO membranes with high permselectivity and anti-biofouling properties were fabricated by nanoparticles incorporation and anti-biofouling grafting.Hydrotalcite(HT)incorporation was performed with a dual role,enhancing water flux and acting as grafting sites.The HT incorporation increased the water flux without sacrificing the salt rejection,compensating for the loss caused by the following grafting reaction.The exposed surface of HT acted as grafting sites for anti-biofouling agent dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride(DMOTPAC).The combination of HT incorporation and DMOTPAC grafting endowed RO membranes with high permselectivity and anti-biofouling properties.The water flux of the modified membrane PA-HT-0.06 was 49.8 L/m^(2)·h,which was 16.4%higher than that of the pristine membrane.The salt rejection of PA-HT-0.06 was 99.1%,which was comparable to that of the pristine membrane.As to the fouling of negatively charged lysozyme,the modified membrane’s water flux recovery was superior to that of the pristine membrane(e.g.86.8%of PA-HT-0.06 compared to 78.2%of PA-pristine).The sterilization rates of PA-HT-0.06 for E.coli and B.subtilis were 97.3%and 98.7%,much higher than those of the pristine membrane(24.0%for E.coli and 26.7%for B.subtilis).

A green and efficient strategy facilitates continuous solar-induced steam generation based on tea-assisted synthesis of gold nanoflowers

Developing a highly efficient system for solar steam generation(SSG)using a straightforward and eco-friendly method to harvest freshwater is fascinating but challenging.Here,we stir the mixture of brewed tea and HAuCl4 to prepare Au nanoflowers,possessing broad wavelength light absorption and excellent photothermal effects.After freeze-drying the mixture of Au nanoflowers,cellulose nanocrystals(CNCs),and aqueous polyurethane(PU)emulsion,we obtain three-dimensional(3D)porous structures(CNC-PU-Au)for SSG.The whole process does not involve any sophisticated procedure or produce detrimental byproducts.The evaporation rates are 2.24 kg·m^(−2)·h^(−1) for pure water and 2.18 kg·m^(−2)·h^(−1) for seawater using CNC-PU-Au under one sun.The solar energy conversion efficiency is up to 90.92%under one sun illumination.Besides,CNC-PU-Au shows self-driven salt resistance and durability.In outdoors application for seawater desalination,the maximum evaporation rate can maintain at 2.19 kg·m^(−2)·h^(−1) in spring and 3.42 kg·m^(−2)·h^(−1) in summer.These unique features promise the utility of CNC-PU-Au in the ecofriendly water treatment industry.

Modulation of the stereoselectivity and reactivity of glycosylation via (p-Tol)2SO/Tf2O preactivation strategy:From O-, C-sialylation to general O-,N-glycosylation

The synthesis of O-, C-, and N-glycoconjugates has continuously been an attractive research subject due to the growing biological importance of various glycoconjugates. In recent years, by careful changing the glycosylation reaction conditions, especially the amount of activators and the preactivation temperature, （p-Tol）2SO/Tf2O preactivition strategy was developed as a general method for the synthesis of various 0-, C-, and N-glycoconjugates, including related biological active glycoconjugates, such as nucleosides and antigen Lewisa etc. High yields and excellent stereoselectivities were obtained even without the anchimeric assistance at the adjacent position of anomeric carbon. In this review, we predominantly make a review on the progress of the （p-Tol）2SO/Tf2O preactivition strategy from O-, C-sialylation to general O-, N-glvcosvlation.

Calixarenes enabling well-adjusted organic-inorganic interface for inverted organic solar cells with 18.25%efficiency and multifold improved photostability under max power point tracking

Compared with organic solar cells(OSCs) adopting conventional architecture,inverted OSCs have offered generally better stability,where Zn O is the most widely used electron transporting layer(ETL) material.For ZnO-based inverted OSCs,a welltuned interface of organic(active layer)-inorganic(Zn O film) with matched surface energy(γS) is critical for both high performance and high stability.In this work,two typical calixarenes,C4A and Bu C4A,were employed as the tuning agents to adjust this organic-inorganic interface for ZnO-based inverted OSCs.As a result,with PM6:L8-BO as the active layer,significantly promoted power conversion efficiencies(PCEs) from 17.14%(for ZnO) to 18.25%(for ZnO/C4A) and 17.80%(for ZnO/Bu C4A) were achieved.Photodynamic studies indicate that the enhanced performance is due to the faster charge extraction process,the suppressed recombination and more ideal internal electric field in ZnO/calixarene-based devices.In addition,wellmatched interface energy and more ordered molecular aggregation in active layer effectively improved photostability and thermal stability for ZnO/calixarene-based devices.These results indicate that calixarenes could act as effective modifying agents of ZnO to improve inverted OSCs’ performance and stability simultaneously,and likely also stimulate calixarenes’ and other macromolecules’ broader studies in other organic electronic devices.

Fluoride removal from secondary effluent of the graphite industry using electrodialysis:Optimization with response surface methodology

Response surface methodology was utilized to model and optimize the operational variables for defluoridation using an electrodialysis process as the treatment of secondary effluent of the graphite industry. Experiments were conducted using a Box-Behnken surface statistical design in order to evaluate the effects and the interaction of the influential variables including the operational voltage, initial fluoride concentration and flow rate. The regression models for defluoridation and energy consumption responses were statistically validated using analysis of variance (ANOVA);high coefficient of determination values (R^2 = 0.9772 and R^2 = 0.9814;respectively) were obtained. The quadratic model exhibited high reproducibility and a good fit of the experimental data. The optimum values of the initial fluoride concentration, voltage and flow rate were found to be 13.9 mg/L, 13.4 V, 102.5 L/h, respectively. A fluoride removal efficiency of 99.69% was observed under optimum conditions for the treatment of the secondary effluent of the graphite industry.

Synthesis of NiFe2O4 Nanowires with NiO Nanosheet as Precursor via a Topochemical Solid State Method

Large scale NiFe2O4 nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe2O4 annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Feions into NiFe2O4 nanowires. In the beginning stage of synthesizing process, the shape ofNiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400 ℃ to 600 ℃. At last they transformed into nanoparticles from 700 ℃ to 1000 ℃. Thus, the optimized annealing temperature was selected as 600 ℃ because the NiFe2O4 obtained at 600 ℃（N600） exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m^2/kg and the lowest coercivity（Hc） of 8914 A/m.

Multifunction Zno/carbon hybrid nanofiber mats for organic dyes treatment via photocatalysis with enhanced solar-driven evaporation

ZnO-based photocatalytic materials have received widespread attention due to their usefulness than other photocatalytic materials in organic dye wastewater treatment.However,its photocatalytic efficiency and surface stability limit further applicability.This paper uses a one-step carbonization method to prepare multifunctional ZnO/carbon hybrid nanofiber mats.The carbonization creates aπ-conjugated carbonaceous structure of the mats,which prolongs the electron recovery time of ZnO nanoparticles to yield improved photocatalytic efficiency.Further,the carbonization reduces the fiber diameter of the carbon hybrid nanofiber mats,which quadruples the specific surface area to yield enhanced adsorption and photocatalytic performance.At the same time,the prepared nanofiber mats can increase the evaporation rate of water under solar irradiation to a level of 1.46 kg·m^(-2)·h^(-1)with an efficiency of 91.9%.Thus,the nanofiber mats allow the facile incorporation of photocatalysts to clean contaminated water through adsorption,photodegradation,and interfacial heat-assisted distillation mechanisms.

半经验模型指导受体分子结构优化获得效率超过15%的有机太阳能电池

本工作中,在我们发展的半经验模型的指导下,设计合成了两个A-D-A骨架受体分子,6T-OFIC和5T-OFIC.因其较长的共轭骨架,6T-OFIC的截止吸收波长为946 nm.相比于6T-OFIC,因其骨架少一个噻吩单元,5T-OFIC分子的截止吸收波长为927 nm,更接近半经验模型所预测的最佳单结器件的截止吸收波长.最终,基于PM6:5T-OFIC的器件获得了13.43%的能量转换效率,高于PM6:6T-OFIC器件.以F-2Cl作为第三组份,基于PM6:F-2Cl:5TOFIC的三元器件其填充和开压得到了明显的提高,最终获得了15.45%的能量转换效率.