Broadband high-efficiency dielectric metalenses based on quasi-continuous nanostrips

Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical systems.Simultaneous broadband and high-efficiency characteristics are highly attractive for the practical implementation of metasurfaces.However,current metasurface devices mostly adopt discrete micro/nano structures,which rarely realize both merits simultaneously.In this paper,dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this limitation.Via quasi-continuous nanostrips metasurface,a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally demonstrated.The quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000nm and keep a high power efficiency.The average efficiency of the fabricated metalens reaches 54.24%,showing a significant improvement compared to the previously reported metalenses with the same thickness.The proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.

High-efficiency Carbonation Modification Methods of Recycled Coarse Aggregates

To solve the problem of only surface carbonation and realize high-efficiency carbonation of recycled coarse aggregate,the method of carbonated recycled coarse aggregate with nano materials pre-soaking was first put forward.The carbonation effect of modified recycled coarse aggregate with three different carbonation methods was evaluated,and water absorption,apparent density and crush index of modified recycled coarse aggregate were measured.Combined with XRD,SEM,and MIP microscopic analysis,the high-efficiency carbonation strengthening mechanism of modified recycled coarse aggregate was revealed.The experimental results show that,compared with the non-carbonated recycled coarse aggregate,the physical and microscopic properties of carbonated recycled coarse aggregate are improved.The method of carbonation with nano-SiO_(2) pre-soaking can realize the high-efficiency carbonation of recycled coarse aggregate,for modified recycled coarse aggregate with the method,water absorption is reduced by 23.03%,porosity is reduced by 44.06%,and the average pore diameter is 21.82 nm.The high-efficiency carbonation strengthening mechanism show that the pre-socked nano-SiO_(2) is bound to the hydration product Ca(OH)_(2) of the old mortar with nano-scale C-S-H,which can improve the CO_(2) absorption rate,accelerate the carbonation reaction,generate more stable CaCO_(3) and nano-scale silica gel,and bond to the dense three-dimensional network structure to realize the bidirectional enhancement of nano-materials and pressurized carbonation.It is concluded that the method of carbonation with nano-SiO_(2) pre-soaking is a novel high-efficiency carbonation modification of recycled coarse aggregate.

Toward high-efficiency perovskite solar cells with one-dimensional oriented nanostructured electron transport materials

The unique advantages of one-dimensional(1D)oriented nanostructures in light-trapping and chargetransport make them competitive candidates in photovoltaic(PV)devices.Since the emergence of perovskite solar cells(PSCs),1D nanostructured electron transport materials(ETMs)have drawn tremendous interest.However,the power conversion efficiencies(PCEs)of these devices have always significantly lagged behind their mesoscopic and planar counterparts.High-efficiency PSCs with 1D ETMs showing efficiency over 22%were just realized in the most recent studies.It yet lacks a comprehensive review covering the development of 1D ETMs and their application in PSCs.We hence timely summarize the advances in 1D ETMs-based solar cells,emphasizing on the fundamental and optimization issues of charge separation and collection ability,and their influence on PV performance.After sketching the classification and requirements for high-efficiency 1D nanostructured solar cells,we highlight the applicability of 1D TiO_(2)nanostructures in PSCs,including nanotubes,nanorods,nanocones,and nanopyramids,and carefully analyze how the electrostatic field affects cell performance.Other kinds of oriented nanostructures,e.g.,ZnO and SnO_(2)ETMs,are also described.Finally,we discuss the challenges and propose some potential strategies to further boost device performance.This review provides a broad range of valuable work in this fast-developing field,which we hope will stimulate research enthusiasm to push PSCs to an unprecedented level.

Ammonium Metavanadate Fabricated by Selective Precipitation of Impurity Chemicals on Inorganic Flocculants

High purity ammonium metavanadate(NH_(4)VO_(3))is the most vital chemical to produce V2O5,VO2,VN alloy,VFe alloy and VOSO4,which have some prospective applications for high strength steel,smart window,infrared detector and imaging,large scale energy storage system.NH_(4)VO_(3)is usually produced by spontaneous crystallization from the aqueous solution due to its sharp dependence of solubility on the temperature.However,hazardous chemicals in industrial effluent,include phosphorate,silicate and arsenate,causing severe damage to the environment.In this work,these impurities are selectively precipitated onto inorganic flocculants,while the vanadate dissolved in an aqueous solution keeps almost undisturbed.Therefore,high purity NH_(4)VO_(3)is produced by the crystallization from the purified solution.By screening various flocculants and precipitating parameters,polyaluminum sulfate with an optimal amount of 50 g/L,is demonstrated to selectively remove phosphorate,silicate and arsenate,corresponding to the removing efficiency of 93.39%,97.11%and 88.31%,respectively.NH_(4)VO_(3)from the purified solution holds a purity of 99.21%,in comparison with 98.33%in the product from the crude solution.This purifying technology cannot only produce NH_(4)VO_(3)with high added value,but also reduce the environmental pollution of waste liquid.

Selection of Greenhouse Zucchini Varieties and High-Quality,High-Yield and High-Efficiency Cultivation Techniques

[Objectives]To select zucchini varieties suitable for cultivation in Zibo City and test its high-yield cultivation techniques.[Methods]Six zucchini varieties were introduced,and their commercial quality and yield were determined.[Results]The yield of Shengfeier,Xiuyu 170 and Xihulu 309 increased by 11.4%,6.9%and 4.6%,respectively compared with S68(control),and zucchini was straight,looked pleasing to the eye,and had strong disease resistance.[Conclusions]The zucchini varieties were selected and the high-quality,high-yield and high-efficiency cultivation techniques were integrated.

Microbial flocculant and its application in environmental protection

The microbial flocculant is a kind of natural bio polymer and has promising future to be used in the fermentation industry and wastewater treatment. It has been studied in details in many countries, such as U.S.A, Japan. This paper reviewed the development on microbial flocculant basic studies and applications, including flocculant production microorganisms, chemical and components of microbial flocculants, flocculation mechanism of microbial flocculants, capability of microbial flocculants and influence factors, and culture conditions for flocculant production. The application cases of microbial flocculants were also discussed.

A cleaner two-step synthesis of high purity diallyldimethylammonium chloride monomers for flocculant preparation

In order to improve the flocculation efficiency of polydiallyldimethylammonium chloride（PDADMAC）, high molecular weight PDADMAC should be prepared from high purity diallyldimethylammonium chloride（DADMAC） monomers. In this paper, a cleaner method with microwave irradiation and alkali solidification was proposed for preparing high pure DADMAC by selective heating under low temperature, and the prepared high purity DADMAC is characterized using FTIR and atomic absorption spectrometry. The new method provides a solution to the key technical problem of PDADMAC synthesis. Comparing with the conventional methods, the results showed that the advantages of the novel synthesis include： （a） high purity DADMAC is improved from 57% to 71% ; （b） reaction time of tertiary amine preparation is shortened from 6 h to 7 min; （c） water instead of acetone was used as reaction medium; （d） toxic by-products, wastewater and waste gas are eliminated. Flocculant made from the synthesized high purity DADMAC monomers was proved more efficient in flocculation tests.

Characteristics and Culture Conditions of a Bioflocculant Produced by Penicillium sp.

Objective To study the characteristics of a bioflocculant named MBF7 produced by Penicillum strain HHE-P7 and the effects of cultivation conditions on bioflocculant production. Methods The chemical group in the bioflocculant molecules was shown by Fourier transform infrared （FTIR） spectra, and the average molecular weight of MBF7 was estimated by gel permeation chromatography. The effects of medium components on bioflocculant production and flocculating activity were studied. Results Phospho-, amino-, hydroxyl, and carboxyl groups were the major fractions of MBF7, and the molecule weight was about 3.0 × 10^5 Da. In addition, the carbon and nitrogen sources favorable for the bioflocculant production were glucose and yeast extract respectively. When the initial pH of the medium was adjusted to 5.0, high flocculant efficiency could be achieved. Conclusion The bioflocculant MBF7 is a new macromolecule with high flocculating efficiency for Kaolin suspension, and could be produced under appropriate culture conditions.

Flocculation performance of a novel synthesized flocculant with low ecological risk

Combined flocculants with low ecological risk are urgently required in water supply and wastewater treatment in China. A novel flocculant was thus developed under the condition of low ecological risk(noted as CAS). The experiments to examine wastewater treatment performance of the new product showed that there was favourable performance in the flocculation process in contrast to commercial flocculants in treating kaolin suspensions, municipal effluent and domestic wastewater. Flocculation performance included the turbidity removal rate, sediment character and a decrease in COD(chemical oxygen demand). The sediment time of flocculation is short and the removal rate of turbidity treated by CAS is high compared with PAC(polyaluminum chloride), PAM(polyacrylamide) and the combined addition of PAC and PAM. The optimal concentration required to affect flocculation processes is dependent on kaolin concentration and the character of the wastewater within the range examined. It also showed that CAS is effective to treat wastewater with high turbidity.

Evaluation of flocculation characteristics of kaolinite dispersion system using guar gum:A green flocculant

This paper reports the systematic investigation on the flocculation,sedimentation and consolidation characteristics of kaolinite using guar gum as a green flocculant.In-situ flocculation behavior of kaolinite at various pH,guar gum dosages,and ionic strength were studied using a light scattering technique.The effect of these parameters on the settling rate,solid consolidation,and supernatant liquid clarity was recorded.The morphology of kaolinite and flocculated kaolinite aggregates were analyzed using FESEM.The morphology studies suggest that it is poorly crystalline with multiple steps on edge,broken edge;laminar with high aspect ratio and have rough basal surface.The complex irregularity on the basal surface and the presence of multiple steps in the edges,broken edges(hydroxyl groups)have facilitated the guar gum adsorption.The isoelectric point of kaolinite is pH 3.96.The pH,ionic strength and flocculant dosage have a significant effect on the kaolinite settling rate.The guar gum has exhibited excellent turbidity removal efficiency at pH 5.The turbidity removal is inefficient at pH 10.However,guar gum has shown high turbidity removal with 80%transmission at pH 10 in the presence of a KNO3 electrolyte.

Experimental research on Phanerochaete chrysosporium as coal microbial flocculant

The flocculation effect of the Phanerochaete chrysosporium on the coal slurry were studied by orthogonal experimental method in this study.The results of research show that the P.chrysosporium has a good effect on flocculating coal slurry.The optimum combination of the experimental is the P.chrysosporium,which is cultured in 2 days,mixed with 2 mL coagulant and 2 mL broth.The flocculant is a broken liquid with pH value of 6.The hightest flocculation ratio is 93.5%.The result of FTIR shows that the biological extraction of P.chrysosporium contains a lot of acidic polysaccharides that has the effect on flocculation.Microbial flocculant molecules and particles of coal slurry could be flocculated by‘‘absorption bridge’’.

Application of organic polymeric flocculants in centrifugal dewa-tering of oil refinery sludge

In order to evaluate the applicability of the organic polymeric flocculants(OPF) in the treatment of oil refinery sludge, experiments were conducted to show that OPF have better performance of flocculation than inorganic flocculants. Both the anionic and cationic OPF have satisfactory flocculation efficiency in oil sludge treatment, but the latter are more cost efficient. Among the over 20 types of flocculants tested, 2 OPF(CPAM 2 and HPAM 2) were selected as the treatment agents, based on their good treatment performances, oil resistance and economic feasibility. It was demonstrated in the industrial scale centrifugal dewatering experiments that the application of either CPAM 2 or HPAM 2 could achieve high treatment efficiency of the oil sludge dewatering and reduce the COD of centrifugal liquid to less than 1000 mg/L.

DMC-grafted cellulose as green-based flocculants for agglomerating fine kaolin particles

Novel cellulose based flocculants C-g-P(DMC) with various chain architectures are synthesized through a situ graft copolymerization. The cationic ammonium chloride group(DMC) is grafted onto cellulose by two separate inverse emulsion polymerization with γ-methacryloxypropyl trimethoxy silane(KH-570) and double bond addition reactions, which is a new and simple method to employ KH-570 as a bridge for the connection of cellulose matrix and DMC group. The effects of pH, flocculant dose, standing time on turbidity of kaolin suspensions and particle sizes have been studied systematically. In addition, the response surface methodology(RSM) study confirms that PAC and C-g-P(DMC)have synergy in turbidity removal with a higher removal efficiency of 98.32%. Moreover, C-g-P(DMC) 1 has higher removal efficiency with 96.5% at a low dosage of 0.6 mg L^(-1) and better floc properties than C-g-P(DMC) 2 and C-g-P(DMC) 3, suggesting that the length and quantity of cationic branch chains play a crucial role in Kaolin flocculation due to their dramatically enhanced bridging effects.

Application Research Status and Development Prospect of Microbial Flocculant

Microbial flocculant （MBF） is a kind of novel flocculant, which is widely used for the food industry, highly concentrated organic waste water treatment and the urban water supply technology. Due to its characteristics of superior flocculation effect, without secondary pollution to the environment and being easily degraded, MBF has been emerging as a hotspot of water treatment research in recent years. In this paper, the latest progress of the preparation of MBFs and the flocculating mechanism were presented. The practical application research of MBFs for water treatment was reviewed. Finally, suggestions and development prospect of research on MBFs were discussed.

Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.

Screening and flocculating properties of bioflocculant-producing microorganisms

Screening of bioflocculant-producing microorganisms was carded out. A strain that secreted excellent bioflocculant was isolated from municipal sewage using the spread plate technique, identified as Klebsiella sp. by the analytical profile index （API） identification system, and named A9. Several important factors that had an effect on A9＇s bioflocculant-producing and flocculating activity were studied. A total of 4 g/L Kaolin suspension was used to measure the flocculating activity of the bioflocculant from A9. It was found that maltose and urea were Ag＇s best carbon and nitrogen sources, respectively, and the flocculating activity of the flocculating agent from A9 was markedly increased by the addition of trivalent cations such as Fe^3＋ and Al^3＋; furthermore, the bioflocculant produced by A9 was most effective when the pH value was 6.0.

Screening of flocculant-producing microorganisms and flocculating activity

A strain saccharomycete STSM-1 with high flocculanting activity was isolated from activated sludge with conventional methods. The high production rate and the low cost STSM-1 medium was obtained by selecting different kinds of media, carbon source, nitrogen source and inorganic salt ion. The best flocculant-producing conditions were found by changing medium initial pH, culture temperature and ventilation flow. The best flocculating effect was obtained by changing positive ion types, density and concentration of flocculant.

Preparation and PerformanceAnalysis of Inorganic Polymer Flocculant PZFSiC

A new inorganic polymer flocculant-PZFSiC (zinc-iron-silicate polymer composite) is prepared by adding acid into a high modulus solution of water glass and introducing appropriate metallic ions(M) including Zn and Fe. The influence on flocculability of factors such as the mole ratios of M to SiO2,stirring time and pH are discussed .And the optimal preparing technical parameters are obtained by orthogonal tests. The optimum technical conditions of flocculation are determined. The result shows that when less PZFSiC is added into troubled water or waste water, turbidity removal can hit 98%, COD removal can exceed 93%. The water sample treated is clear and of good quality. These results also indicate that PZFSiC is a highly effective, nontoxic and benign to the enviroment.

Preparation and Study of a Composite Flocculant for Papermaking Wastewater Treatment

A high flocculation performance composite flocculant was prepared with sodium alginate, polyaluminium ferric chloride and cationic polyacrylamide. And the composite flocculant was used in papermaking wastewater treatment. Results indicated that it achieve the best flocculation performance when the raw material mass ratio was 2:1:1, the dosage of the composite flocculant was 20 mg/L, and the removal efficiency of COD and turbidity with this composite flocculant reached 89.6% and 99.2%, respectively.

Study on Production and Flocculation Conditions of Bio-Flocculant

One strain of bacteria which shows very high flocculation characteristics is found. It is identified as a Pseudomonas species. The influence of components of culture medium on the flocculant production by Pseudomonas sp. is studied.The results of our experiments show that the higbest level of bio-flocculant accumulation is obtained and the hioflocculant can efrectively flocculate kaolin clay on condition that this stralu is grown in the medium containing glucose as carbon source, aud (NH4)2SO4 as nitrogen source, with the yend extract being added. In addition, some kinds of cationic ions have some influences on the flocculation rate of kaolin clay with tbe Al3+ions in particular.