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A novel strategy for controlling mosquito-borne diseases, such as dengue, malaria and Zika, involves releases of Wolbachia-infected mosquitoes as Wolbachia cause early embryo death when an infected male mates with an uninfected female. In this work, we introduce a delay differential equation model with mating inhomogeneity to discuss mosquito population suppression based on Wolbachia. Our analyses show that the wild mosquitoes could be eliminated if either the adult mortality rate exceeds the threshold δ A ∗ or the release amount exceeds the threshold r ∗ uniformly. We also present the nonlinear dependence of δ A ∗ and r ∗ on the parameters, respectively, as well as the effect of pesticide spraying on wild mosquitoes. Our simulations suggest that the releasing should be started at least 5 weeks before the peak dengue season, taking into account both the release amount and the suppression speed. [ABSTRACT FROM AUTHOR]

Abstract Dengue fever and Zika are mosquito-borne diseases threatening human health. A novel strategy for mosquito-borne disease control uses the bacterium Wolbachia to block virus transmission. It requires releasing Wolbachia infected mosquitoes to exceed a threshold level. Since an accurate forecast for temperature and rainfall, the major environmental conditions regulating the mosquito dynamics, is often not available over a long time period, it is important to explore how the threshold releasing level changes in random environments. In this work, we estimate the threshold level in a stochastic system of differential equations where the reproduction rates of mosquitoes change randomly. We prove that the threshold level is, surprisingly, defined by a deterministic curve that does not fluctuate with environmental conditions. The major difficulty in the proof is to construct various auxiliary curves to limit the dynamic behaviors of the whole family of innumerable solutions satisfying a given initial condition. [ABSTRACT FROM AUTHOR]

Highlights • Infection of Wolbachia in mosquitoes blocks them from transmitting dengue and Zika. • We studied Wolbachia spreading dynamics under fluctuating environmental conditions. • The threshold infected mosquito release level for Wolbachia invasion is estimated. • The alarm period is defined as a measure of mosquito-borne disease transmission risk. • Frequent fluctuation in climatic conditions reduces the risk of disease transmission. Abstract Mosquito-borne diseases such as dengue fever and Zika kill more than 700,000 people each year in the world. A novel strategy to control these diseases employs the bacterium Wolbachia whose infection in mosquitoes blocks virus replication. The prerequisite for this measure is to release Wolbachia -infected mosquitoes to replace wild population. Due to the fluctuation of environmental conditions for mosquito growth, we develop and analyze a model of differential equations with parameters randomly changing over multiple environmental regimes. By comparing the dynamics between the stochastic system and constructed auxiliary systems, combined with other techniques, we provide sharp estimates on the threshold releasing level for Wolbachia fixation. We define the alarm period of disease transmission to measure the risk of mosquito-borne diseases. Our numerical simulations suggest that more frequent inter-regime transitions help reduce the alarm period, and the disease transmission is more sensitive to the average climatic conditions than the number of sub-regimes over a given time period. Further numerical examples also indicate that the reduction in the waiting time to suppress 95% of wild population is more evident when the releasing amount is increased up to a double of the wild population. [ABSTRACT FROM AUTHOR]

Dengue fever creates more than 390 million cases worldwide yearly. The most effective way to deal with this mosquito-borne disease is to control the vectors. In this work we consider two weapons, the endosymbiotic bacteria Wolbachia and predators of mosquito larvae, for combating the disease. As Wolbachia-infected mosquitoes are less able to transmit dengue virus, releasing infected mosquitoes to invade wild mosquito populations helps to reduce dengue transmission. Besides this measure, the introduction of predators of mosquito larvae can control mosquito population. To evaluate the impact of the predators on Wolbachia spreading dynamics, we develop a stage-structured five-dimensional model, which links the predator-prey dynamics with the Wolbachia spreading. By comparatively analysing the dynamics of the models without and with predators, we observe that the introduction of the predators augments the number of coexistence equilibria and impedes Wolbachia spreading. Some numerical simulations are presented to support and expand our theoretical results. [ABSTRACT FROM AUTHOR]

Dengue fever is a mosquito-borne viral disease with 100 million people infected annually. A novel strategy for dengue control uses the bacterium Wolbachia to invade dengue vector Aedes mosquitoes. As the impact of environmental heterogeneity on Wolbachia spread dynamics in natural areas has been rarely quantified, we develop a model of differential equations for which the environmental conditions switch randomly between two regimes. We find some striking phenomena that random regime transitions could drive Wolbachia to extinction from certain initial states confirmed Wolbachia fixation in homogeneous environments, and mosquito releasing facilitates Wolbachia invasion more effectively when the regimes transit frequently. By superimposing the phase spaces of the ODE systems defined in each regime, we identify the threshold curves below which Wolbachia invades the whole population, which extends the theory of threshold infection frequency to stochastic environments. [ABSTRACT FROM AUTHOR]

Abstract: Establishing stable cropping systems was vital in antiquity, assuring certain yields and enabling ancient people to settle, thus possibly causing various modern food habits and culture to form around the world, especially in cereal-cultivation-dominated countries. China, one of the most famous ancient agricultural countries, has a long history of rice planting, and the fire-irrigation paddy cultivation system is prevalent in the lower Yangtze region, which is considered a rice domestication center. However, its origin and cultivation pattern remain unclear. We studied a famous agricultural vestige, the Chuodun site, involved in rice planting in the lower Yangtze River Delta in eastern China, during the Neolithic Age. Clear evidence from archaeology, paleobiology, pedology and biogeochemistry suggest both that the rice fire-irrigation cultivation system formed during the Neolithic Age and that ancient peoples lived there steadily. Under this extensive cultivation system, soil structures and properties changed significantly; in particular, it left more black carbon in the soil and increased the organic carbon soil stability, which can be used to reconstruct prehistoric environments. Meanwhile, the prevalent fire-irrigation paddy cultivation system used by farmers in this area, though for a different purpose than ancient people, may be inherited from the Neolithic Age. [Copyright &y& Elsevier]

• Biochar aging on the basis of sorption performance of phenanthrene. • Biochar was produced from rice husks at 350 °C. • Oxygen-containing functional groups on the surface increased during aging. • Adsorption capability decrease under low temperature by 34.10%. Herein, we have described the important role about biochar aging on the basis of sorption performance of phenanthrene. Biochar used in this study was produced from rice husks at 350 °C and its aging has been manufactured by laboratory incubation. The results showed that an aging layer formed which contains oxygen-bearing groups on to the surface increased during the course of aging. Aging decreased the adsorption capability of biochar obtained under low temperature by 34.10%, ascribed as the increase of oxygen bearing polar moieties; specifically the hydroxyl species that negatively affected sorption of phenanthrene. [ABSTRACT FROM AUTHOR]

Mosquito-borne diseases kill more than 700, 000 people a year, and the toll continues to rise. Controlling mosquito population is the key measure to prevent mosquito-borne diseases. Releasing sterile male mosquitoes to suppress wild mosquito population is an environmentally friendly and efficient method, which has been proven to successfully eliminate wild mosquitoes in laboratory, but it is difficult to achieve such effectiveness in the field. The diapause of mosquito eggs is considered an important factor hindering mosquito population suppression. In this paper, we formulate an ordinary differential equation model to discuss the impact of diapause eggs on mosquito population suppression. We prove that there exists at most one periodic solution in our model, and obtain sufficient and necessary conditions for the existence of an unique periodic solution. We give numerical simulations to confirm our theoretical results. • We reveal that diapause eggs are beneficial for mosquitoes to resist intervention. • We estimate the initial position of the periodic solution of a suppression model. • We obtain the necessary and sufficient condition for eliminating wild mosquitoes. [ABSTRACT FROM AUTHOR]

Cement kiln co-processing is a major technique for disposing of hazardous solid wastes, yet the formation of toxic soluble compounds during the process may induce further contamination upon leaching. Hexavalent chromium compounds are generally considered to be the only soluble chromium species in cement. Here, we identified Ca5(CrO4)3O0.5, a compound with solubility of 10–150 mg/L at 20–50 °C containing pentavalent chromium, in cement co-processed with tanning sludge at temperatures higher than 800 °C. This hexagonal crystal is partly responsible for the leachability of chromium from cement. Approximately 10% of the soluble chromium compounds in the co-processed cement were attributed to the formation of Ca5(CrO4)3O0.5. The formation of Ca5(CrO4)3O0.5 results rather from the reduction of CaCrO4 by free CaO at 800–1300 °C than from the oxidation of trivalent chromium. Our findings imply that the formation of pentavalent chromium during cement production could pose a threat to environmental safety. [ABSTRACT FROM AUTHOR]

To suppress wild population of Aedes mosquitoes, the primary transmission vector of life-threatening diseases such as dengue, malaria, and Zika, an innovative strategy is to release male mosquitoes carrying the bacterium Wolbachia into natural areas to drive female sterility by cytoplasmic incompatibility. We develop a model of delay differential equations, incorporating the strong density restriction in the larval stage, to assess the delicate impact of life table parameters on suppression efficiency. Through mathematical analysis, we find the sufficient and necessary condition for global stability of the complete suppression state. This condition, combined with the experimental data for Aedes albopictus population in Guangzhou, helps us predict a large range of releasing intensities for suppression success. In particular, we find that if the number of released infected males is no less than four times the number of mosquitoes in wild areas, then the mosquito density in the peak season can be reduced by 95%. We introduce an index to quantify the dependence of suppression efficiency on parameters. The invariance of some quantitative properties of the index values under various perturbations of the same parameter justifies the applicability of this index, and the robustness of our modeling approach. The index yields a ranking of the sensitivity of all parameters, among which the adult mortality has the highest sensitivity and is considerably more sensitive than the natural larvae mortality. [ABSTRACT FROM AUTHOR]

Spent petroleum refining catalyst is regarded as the important secondary resource for valuable metals. However, common recycling strategies, including soda roasting, acid and alkaline solutions leaching and chemically precipitation, produced large quantities of high salinity wastewater. This study proposed an efficient method to recovery of Mo and Ni from the spent hydrodesulfurization (HDS) catalyst via O 2 -rich roasting and organic acid leaching with the advantage of less salinity wastewater production. The transformation of Mo(IV) into soluble Mo(VI) was enhanced by O 2 -rich atmosphere roasting, and 98.64% of Mo(IV) was oxidized at 650 ℃ for 2 h in atmosphere containing 30% of O 2. The oxidation process of Mo(IV) was agreed with the shrinkage pore model, and regulated by surface reaction and internal diffusion. 97.97% of Mo(VI) was leached from roasted product by oxalic acid, separated with complexation extraction agent of Ala-TBP and recovered as (NH 4) 8 Mo 10 O 34 and (NH 4) 2 Mo 3 O 10 by evaporative crystallization. Ni was leached out from spent catalyst with 1 mol/L acetic acid, and precipitated as NiC 2 O 4 with oxalic acid. 95.92% of Mo and 96.77% of Ni were recovered from spent HDS catalyst with this recycling route. This study provided a high-efficient and eco-friendly method to recovery of valuable metals from spent catalyst. [Display omitted] • MoS 2 oxidation was improved during roasting in O 2 -rich atmosphere. • MoS 2 oxidation process was agreed with shrinkage pore model. • O 2 dissociative adsorption occurred on the MoS 2 and O charge was transferred to S. • Mo(VI) was extracted and enriched with complexation extraction agents Ala-TBP. [ABSTRACT FROM AUTHOR]

Transcriptional bursting has been attributed to the random switch between the off and on states of genes. Previous studies modeled gene activation as a process involving ordered multiple rate-limiting steps. Here, we aimed to understand how multi-step gene activation regulates the dynamical mRNA distribution in isogenic cell populations. We focused on both inactive and active genes for which the gene shows a longer average duration in the off and on states, respectively. We developed a method to calculate the mRNA distribution and demonstrated the unstable dynamical bimodal distribution induced by multi-step activation. The suppression of bimodality requires only a few activation steps and is achieved by triggering more cells to express the gene. In the gene-expressing cell population, multi-step gene activation modulates the transcription distribution in a bidirectional manner: the inactive gene is transcribed with enhanced heterogeneity, whereas the active gene is facilitated to generate homogeneous transcription dynamics. These regulation scenarios guide the understanding of the network structure of signaling pathways that direct gene activation. [ABSTRACT FROM AUTHOR]

FeOCl-MoS2 was synthesized via calcination, which possessed excellent adsorption performance for methyl orange (MO). The characterization results showed that the FeOCl-MoS2 was formed between MoS2 and FeOCl phases, while a remarkable improvement in specific surface area and porosity was obtained in comparison with pure FeOCl and MoS2. The adsorption experiment results showed that the adsorption capacity of MO dye at 25 °C could reach 1615.11 mg/g. In addition, the pseudo-second-order kinetic model (R2 > 0.99) has a good applicability to describe the adsorption of MO onto FeOCl-MoS2. Langmuir isotherm model (R2 > 0.99) can describe the adsorption process well, proving that the adsorption is surface-controlled monolayer adsorption. Thermodynamic analyses showed the adsorption is an exothermic process and has spontaneity in nature. The adsorption of MO onto FeOCl-MoS2 is attributed to electrostatic interaction. In particular, the adsorption capacity could still reach 82.1% of the initial adsorption capacity by alkali washing after five cycles. Hence, this study reveals that FeOCl-MoS2 could be a high-efficient adsorbent for dyes removal from wastewaters. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo leaching efficiency was improved with the use of H 2 O 2 and K 2 S 2 O 8. • Nano zero-valent iron further enhanced the leaching efficiency of Mo. • The leaching process of Mo conformed to the shrinkage core model. • Mo leaching and oxidation reaction occurred simultaneously in nZVFe + H 2 O 2 + H 2 SO 4 system. • MoS 2 was dissolved into Mo4+ and then oxidized into Mo6+ in nZVFe + K 2 S 2 O 8 + H 2 SO 4 system. Spent hydrodesulfurization (HDS) catalyst contains considerable amounts of Mo, Ni and V, is an important secondary resource for these valuable metals. Direct acid solution leaching method exhibits poor separation effect from catalyst carrier for Mo due to greater stability of MoS 2. This study explored Mo leaching efficiencies from spent HDS catalyst by Fenton-like oxidation systems (H 2 O 2 and K 2 S 2 O 8), which were frequently employed in the wastewater treatment. To further improve Mo leaching efficiency, nano zero-valent iron (nZVFe) was used to activate H 2 O 2 /K 2 S 2 O 8 and produce more free radicals (·OH and ·SO 4 -). Approximate 96.0 % and 93.3 % of Mo were leached from spent HDS catalyst in nZVFe + H 2 O 2 + H 2 SO 4 and nZVFe + K 2 S 2 O 8 + H 2 SO 4 systems under optimal experimental conditions, increased by 16.2 % and 8.2 % than normal H 2 O 2 (79.8 %) and K 2 S 2 O 8 (85.1 %) system without nZVFe. The leaching process of Mo in both nZVFe + H 2 O 2 + H 2 SO 4 and nZVFe + K 2 S 2 O 8 + H 2 SO 4 systems conformed to the shrinkage core model. Kinetic analysis and molecular calculation demonstrated the leaching process of Mo in nZVFe + H 2 O 2 + H 2 SO 4 system was driven by chemical reaction and solid film diffusion, and the leaching and oxidation reactions of MoS 2 occurred simultaneously. However, the leaching process of Mo in nZVFe + K 2 S 2 O 8 + H 2 SO 4 system was driven only by chemical reaction, solid MoS 2 was firstly dissolved into Mo4+ by H+, and then oxidized into Mo6+ by ·SO 4 -. The economic and environmental impacts evaluation indicated that the separation of Mo from spent HDS catalysts by nZVFe + H 2 O 2 + H 2 SO 4 was assigned as a better choice than normal H 2 O 2 and K 2 S 2 O 8 system without nZVFe due to higher leaching efficiency and lower cost. [ABSTRACT FROM AUTHOR]

• Electroplating sludge introduced into the production of fired brick is feasible. • Electroplating sludge increased the porosity and water absorption. • Prepared bricks meet compressive strength required by standard. • Long leaching experiment showed bricks containing sludge were environmentally safe. Electroplating sludge (ES) is regularly listed as the hazardous waste in all the world, and its treatment is always a pressing problem for environment safety. This study introduced this sludge into the production of fired clay bricks in lab scale, not only consumed a large amount of this sludge but also provided an available raw material for building materials industries. Two types clay, brown clay and red clay, were mixed with ES and used in the production of bricks. Physical property tests showed that the introduction of ES with mass fraction of 10 wt% impacted slightly mass loss, linear shrinkage and bulk density. However, water absorption increased by 15% and compressive strength declined more than 30%. Porosity analysis showed that the introduction of ES enhanced porosity and enlarged pore volume and size. These negative impacts bought by the incorporation of ES can be remedied by elevating firing temperature. Long periods leaching tests for 10 days proved that the releasing concentrations of all heavy metals (Cu, Zn, Cr and Ni) from fired samples containing 10 wt% of ES were under 1 mg/L, far below the corresponding regulation limitation values. This study indicated that ES could be sustainably used in the manufacturing process of fired bricks or ceramics, and the influences on physical-mechanical properties bought by the introduction of ES could be remedied by elevating firing temperature or others ways. [ABSTRACT FROM AUTHOR]

The introduction of electroplating sludge in the manufacturing of clay brick can be considered a feasible method to consume it, while physical-mechanical performances would degrade significantly and the potential leachability of heavy metals remain. This study proposed an alternative to remedy these negative impacts by adding Na 2 SiO 3. The addition of Na 2 SiO 3 decreased water absorption and promoted compressive strength substantially. Water absorption of bricks fired at 1050 °C for 3 h decreased from 6.05 to 0.56% and compressive strength increased dramatically from 22 to 46 MPa with the adding amount of Na 2 SiO 3 raising from 0 to 20 wt%. The porosity analysis demonstrated the apparent porosity, surface area, pore volume, and pore size decreased significantly, especially at 1050 °C. The mineralogical phase analysis showed the Na 2 SiO 3 reacted with quartz and formed albite, and the albite played an important role in decreasing porosity and enhancing mechanical property. Additionally, Na 2 SiO 3 decreased the leachability of heavy metals, it was mainly due to the decrease in water absorption, surface area, pore volume, and pore size. Prolonging the firing time can also decrease water absorption and enhance compressive strength in the presence of Na 2 SiO 3. These results proved that the addition of Na 2 SiO 3 is a feasible strategy for enhancing the properties and environmentally safe of fired bricks when solid waste was introduced to produce bricks or ceramics. Image 1 • Na 2 SiO 3 reduced water absorption and improved compressive strength of bricks. • Na 2 SiO 3 reduced surface area and pore volume of bricks. • Brick microstructure turned from porous to smooth due to addition of Na 2 SiO 3. • Leaching risk of heavy metals was reduced substantially. [ABSTRACT FROM AUTHOR]

Highlights • The introduction of sludge promoted pore volume and pore size of brick. • Prolonging firing time decreased surface area and porosity. • Heavy metals were immobilized by being incorporated into spinel structure. Abstract The mixing of electroplating sludge in the manufacturing of fired clay products (brick or ceramics) is usually considered as the viable method to disposal of it. However, the introduction of electroplating sludge usually decreases compressive strength and promotes water absorption, which somewhat limits the application of products containing this sludge. In this study, influences of electroplating sludge introduction were examined in terms of microstructure, mineral phase and porosity, for explaining the change in the water absorption and compressive strength. The microstructure analysis showed that the morphology of bricks texture became rough and porous. The porosity of bricks increased remarkably due to the introduction of electroplating sludge. With 10 wt% of electroplating sludge being added, surface area, pore volume and pore size increased by 2, 4, 7, and 2.2 times comparing with there was no electroplating sludge added. Oppositely, prolonging firing time decreased significantly surface area, pore volume and pore size. The increase in pore volume can mainly be attributed to an increase in mesoporous. Additionally, XRD analysis showed that most of heavy metals would be incorporated into spinel structure, and most of spinel will be formed within 1 h. Both the enlarged pore and the formation of spinel are mainly responsible for the increase in water absorption and the decrease in compressive. This study given some possible explanations for the change in the water absorption and compressive strength when electroplating sludge was introduced for the manufacturing bricks or ceramics, and provided directions for finding possible solutions. [ABSTRACT FROM AUTHOR]

The utilization of auxiliary electrode can improve substantially the electrokinetic remediation efficiency of heavy metal contaminated soil. The increase in the auxiliary electrode performance is the key to further promote the electrokinetic remediation efficiency. In this study, two kinds of auxiliary electrodes, pure FeOCl and doped FeOCl with W and S, were prepared and used in the electrokinetic remediation of Cr(VI) contaminated soil. The system equipped with the auxiliary electrode doped FeOCl brought more stable system current (202 mA) and more uniform electric field than blank group (130 mA). The reduction rate of Cr(VI) was increased by 50% due to the presence of Fe2+ and S2-. The accelerating migration of ions by auxiliary electrode was responsible for the improvement in electrokinetic remediation efficiency. Density functional theory (DFT) calculation showed that Cl vacancy formation energies of pure FeOCl, S-doped FeOCl (S/FeOCl) and W-doped FeOCl (W/FeOCl) were 1.29, 1.15 and 1.49 eV respectively, and the ion diffusion barriers were 0.093, 0.099 and 0.148 eV respectively. Calculation results indicated that the doping of S was conducive to the diffusion of Cl ions, and the bonding of W-Cl was stronger than Fe-Cl. The charging and discharging process of auxiliary electrode became easier due to the formation of lower vacancy in S-doped FeOCl, which could bring a higher current for the electrokinetic remediation system. The electrochemical performance of FeOCl doped with W and S was improved obviously. This study provided a further explanation for the positive role of auxiliary electrode in electrokinetic remediation system. [Display omitted] • The reduction of Cr(VI) was mainly dependent on W4+, Fe2+ and S2-. • The Cl diffusion of FeOCl was influenced by W and S doping. • S doping promoted the Cl diffusion of FeOCl. • Pure FeOCl and doped FeOCl increased the current remarkably. [ABSTRACT FROM AUTHOR]

The introduction of dyeing sludge in the fired brick production is an economic and practical disposal approach. Wet dyeing sludge with high moisture usually produces block mass during mixing process of raw materials, not only reduces the production efficiency but negatively impacted products engineering properties. This study proposed a highly efficient method, wet sludge firstly being pelleted and then introduced in the production of fired bricks, to reduce the negative impacts on mixing process and the products quality. It was proved that the introduction of dyeing sludge pellets remarkably improved physical and mechanical properties of fired bricks. Especially, water absorption declined by 12% and compressive strength increased by 35% comparing with dyeing sludge without pelleting. The engineering properties of fired bricks containing 25 wt% sludge pellets are similar with that containing 15 wt% sludge without pelleting. The decrease in water absorption and porosity is mainly attributed to the reduction in number and volume of pores with diameter below 100 nm. It was considered that pellets with greater density and higher strength might play a role as aggregate to improve compressive strength. However, the introduction of sludge pellets with particle size over 8 mm is adverse to improving properties of products, because a large amount of macropore with diameter over 100 μm is produced, and destroys the homogeneous and compact structure of products. The optimal sludge pellet size is in the range of 2–6 mm based on products performance. The leaching toxicity of heavy metals from products is far lower than regulatory limitation. This study provides an advanced method to promote the disposal efficiency of solid waste and improve the engineering quality of products. • The introduction amount of dyeing sludge is promoted remarkably. • Physical and mechanical properties are improved significantly. • The optimal particle size of sludge pellets is 2–6 mm. • Pore volume below 100 nm in fired brick are reduced. [ABSTRACT FROM AUTHOR]

• A novel and high efficient approach to disposal of dyeing sludge is proposed. • Physical and mechanical properties are improved significantly. • The optimal particle size of sludge pellets is 2–6 mm. • The number and volume of pores below 100 nm are reduced due to pellets. The introduction of dyeing sludge in the production of fired brick is an economic and practical disposal approach. However, wet dyeing sludge is easy to form block mass during the mixing process of raw materials due to the high moisture content, which affected the production efficiency and destroyed the homogeneous structure of the fired brick, posing a negative impact on the engineering performance of the fired brick. In this study, wet sludge firstly is firstly pelleted and then introduced in the production of fired bricks to reduce the negative impacts on mixing process and the products quality. The results showed that the introduction of dyeing sludge pellets significantly improved the physical and mechanical properties of fired bricks. Compared with bricks incorporating dyeing sludge, water absorption is reduced by 24 % and compressive strength is increased by 101.6 %. The physical and mechanical properties of fired bricks incorporating 30 wt% of pelleting sludge are similar with bricks incorporating 20 wt% dyeing sludge without pelleting. The reduction in water absorption and porosity compared to that incorporating sludge without pelleting was mainly due to the reduction in the number and volume of pores of the same size. However, the introduction of more than 30 wt% dyeing sludge pellets is not conducive to improving the performance of the product, because a large number of macropores with size larger than 100 μm will be generated, which destroys the uniform and dense structure of the product. To ensure product quality meet the standard, the maximum dosage of dyeing sludge with pelleting is controlled below 30 wt%. This study provides an advanced method to improve the treatment efficiency of solid waste and the quality of products. [ABSTRACT FROM AUTHOR]

Incineration is an alternative approach to disposal of tannery sludge due to the significant volume reduction. But the Cr(III) oxidation caused by Ca hydrates or carbonates in the incineration process could lead to incineration residue exceeding the required standard in the leaching toxicity of Cr(VI) and being listed in hazardous waste. A novel method of suppressing Cr(III) oxidation by introducing sulfates during the incineration of tannery sludge is proposed in this study. Cr(III) oxidation can be effectively inhibited with the introduction of NH 2 SO 3 H, NH 4 HSO 4 and NaHSO 4 at n (S)/ n (Ca) over 1.2. The combination reaction of sulfates and CaO prevents the Cr(III) oxidation. The inhibition of Cr(III) oxidation by sulfates is the most effective at 700–900 °C because almost all Ca is incorporated into CaSO 4 phase. NH 2 SO 3 H and NH 4 HSO 4 perform better in inhibiting Cr(III) oxidation than NaHSO 4. The intermediate product of Cr 2 (SO 4) 3 , which is formed below 500 °C, would decompose into Cr 2 O 3 with the temperature of over 600 °C. However, part of Cr 2 O 3 is still oxidized into CaCrO 4 aroused by CaSO 4 at a temperature of over 900 °C. Kinetic study showed Cr(III) oxidation could be effectively suppressed even if the heating time extends to 2 h at 800 °C. Toxicity Characteristic Leaching Procedure showed that the leaching concentrations of Cr(VI) from incineration residues with the introduction of NH 2 SO 3 H and NH 4 HSO 4 at n (S)/ n (Ca) of over 1.2 satisfied the requirement, and resultant residues could not be classified as hazardous waste. Due to inhibiting Cr(III) oxidation with high efficiency at 700–900 °C, the introduction of sulfates can be considered as a potential approach to prevent Cr(VI) formation during the incineration of tannery sludge by fluidized bed incinerator. • Cr(III) oxidation are suppressed by sulfates during heating of tannery sludge. • Inhibiting Cr(III) oxidation is strongly determined by temperature. • NH 2 SO 3 H and NH 4 HSO 4 are more effective in hindering Cr(III) oxidation than NaHSO 4. • Cr(III) oxidation is suppressed with sintering time being extended to 2 h. • Incineration residues cannot be listed as hazardous waste with adding of sulfates. [ABSTRACT FROM AUTHOR]

The catalyst Mo–Ni/Al 2 O 3 is commonly used in the hydrodesulfurization of petroleum fractions. The catalyst is discarded when its catalytic activity does not meet the requirement of the process, and the spent catalyst is usually classified as hazardous waste due to its significant heavy-metal content. The spent catalyst usually has a high commercial recovery value as a secondary resource for high-value metals, but the simple and high efficiency recovery method is still lacking. A high-efficiency recovery method for Mo and Ni from spent Mo–Ni/Al 2 O 3 catalyst via soda roasting and solvent extraction was developed in this study. MoO 3 interacts with Al 2 O 3 and forms a new phase, Al 2 (MoO 4) 3 , during blank roasting at 600–700 °C. Al 2 (MoO 4) 3 further transforms into NaMoO 4 during soda roasting at 950 °C, and over 99.1% of Mo can be leached using hot water (60 °C). Solvent extraction with the trioctyl tertiary amine (N235) is employed to separate Mo from the leaching solution, and approximately 99.45% of Mo can be enriched through single-stage extraction. Around 99.2% of Mo can be stripped from loaded N235 using 8 M NH 3 •H 2 O. Further, PO 4 3− and SiO 3 2− can be removed from the stripping solution using Mg(NO 3) 2 , and Mo is recycled in the form of MoO 3 , i.e., a product of the ammonium precipitation and calcining process. Over 99.3% of Ni can be leached from the solid residue using 30% volume fraction of H 2 SO 4 and the solvent extraction can be enriched using diiso-octylphosphate (DP). Ni is finally recycled from the stripping solution as NiSO 4• 2H 2 O via evaporative crystallization. The total Mo and Ni recovery efficiencies of the newly developed integrated approach are 97.8% and 98.1%, respectively. Al is also recycled in the form of α-Al 2 O 3 via chemical precipitation and calcination. The proposed approach is simple, with a high recovery rate and high selectivity, and can be applied to the recycling and disposal of spent Mo–Ni/Al 2 O 3 catalyst. • A new recovery way for Mo and Ni from spent catalyst was developed. • MoO 3 interacts with Al 2 O 3 and forms a new phase of Al 2 (MoO 4) 3. • P and Si can be removed from stripping solution by Mg salts. • The total recovery efficiency of Mo and Ni can be obtained at 97.8% and 98.1%. [ABSTRACT FROM AUTHOR]

• The presence of salts influenced negatively properties of fired brick. • Desalination is required for the reuse of fly ash in brick production. • Chemically bonding forms of heavy metals changed after firing. • Leaching of heavy metals below regulation standards. The introduction of municipal solid waste incineration fly ash (MSWIF) during manufacturing process of fired bricks is a promising disposal method. However, the quality of products is negatively reduced and environmental risk increased significantly with the addition of MSWIF. This study proposed a novel approach to enhance the quality and environmental safety of fired brick by adding electric arc furnace slag (EAFS) as the pore plugger, which could overcome disadvantages brought by the introduction of MSWIF. Results showed that linear shrinkage and bulk density increased with the addition of EAFS, while water absorption and apparent porosity are reduced by more than 50%. The fracture microstructure of fired brick changed from porous to smooth with the addition of EAFS. The thermal conductivity declined by 25% and 30% at 1050 and 950 °C, and compressive strength was enhanced by 50% with the addition of 30 wt% EAFS. The chemically combination reactions between raw materials, such as the formation of albite, are promoted remarkably with the addition of EAFS. The leaching concentrations of heavy metals are far lower than regulatory limitations and environmental safety are enhanced significantly. In all, the addition of EAFS can promote the quality and environmental safety of fired brick, and can be used as an effective way to solve problems caused by introducing heavy metal solid waste. [ABSTRACT FROM AUTHOR]

Solid solutions of (Al x Cr 1- x) 2 O 3 and (Fe x Cr 1- x) 2 O 3 are predominant compounds containing Cr in solid waste and are frequently formed during thermal treatment of solid waste. (Al x Cr 1- x) 2 O 3 and (Fe x Cr 1- x) 2 O 3 have superior thermomechanical properties and excellent corrosion resistance. However, oxidation and reduction reactions of the Cr in these solid solutions seriously affect their chemical stabilities and the environmental risks posed by the final products. In this study, first the reaction behaviors of (Al x Cr 1- x) 2 O 3 and (Fe x Cr 1- x) 2 O 3 at high temperatures were analyzed and whether the incorporation of Cr(III) in solid solutions can prevent Cr(III) from being oxidized was determined. Both (Al x Cr 1- x) 2 O 3 and (Fe x Cr 1- x) 2 O 3 without the presence of CaO exhibit good thermal stability at high temperatures. However, the participation of CaO induces Cr(III) oxidation in (Al x Cr 1- x) 2 O 3 and (Fe x Cr 1- x) 2 O 3 at 500–1000 °C. Cr(III) oxidation in these solid solutions is accompanied by the formation of CaCrO 4 and Fe 2 O 3 or Al 2 O 3. Al 2 O 3 combines with CaCrO 4 and further forms a more stable Cr(VI) compound (e.g., Ca 4 Al 6 O 12 CrO 4). While Fe 2 O 3 combines with CaCrO 4 at 1000–1200 °C. This is accompanied by the formation of CaCr 2 O 4 and CaFe 2 O 4 , which effectively promotes the reduction of Cr(VI). Moreover, part of the CaCr 2 O 4 transforms into a more stable phase (i.e., FeCr 2 O 4) at 1200–1300 °C. Although the incorporation of Cr(III) in these solid solutions cannot prevent Cr(III) oxidation completely at high temperatures, the Cr(III) oxidation in these solid solutions is still suppressed compared with Cr 2 O 3. The results of this study provide further insights into the oxidation and reduction reactions of Cr-hosting compounds during thermal treatment of solid waste. • (Al/Fe x Cr1- x)2O3 can still be oxidized at 600–900 °C. • CaCrO4 combines with Al2O3 and forms Ca4Al6O12CrO4. • The incorporation of Cr in solid solutions depresssed Cr(III) oxidation. • CaCrO4 reacts with Fe2O3 and produces FeCr2O4 at 1300 °C. • Fe2O3 suppresses Cr(III) oxidation comparing with Al2O3. [ABSTRACT FROM AUTHOR]

In this work, we investigate the existence and stability of periodic orbits of a mosquito population suppression model based on sterile mosquitoes. The model switches between two sub-equations as the actual number of sterile mosquitoes in the wild is assumed to take two constant values alternately. Employing the Poincaré map method, we show that the model has at most two T-periodic solutions when the release amount is not sufficient to eradicate the wild mosquitoes, and then obtain some sufficient conditions for the model to admit a unique or exactly two T-periodic solutions. In particular, we observe that the model displays bistability when it admits exactly two T-periodic solutions: the origin and the larger periodic solution are asymptotically stable, and the smaller periodic solution is unstable. Finally, we give two numerical examples to support our lemmas and theorems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electronic structure of FeOCl (001) were regulated by S and Mo doping. • S and Mo doping reduce energy of H 2 O molecule adsorption and dissociation. • S and Mo doping promote the adsorption and dissociation of H 2 O molecule. • The dissociation rate of water molecules was evaluated indirectly. FeOCl is widely used in cathode of lithium ion battery, matrix material and reaction catalyst. In which, the interactive behavior of H 2 O on FeOCl surface is closely related with the property of FeOCl materials. In this study, the influences of S and Mo doping on H 2 O molecule adsorption and dissociation on FeOCl (010) were explored by DFT calculations and experiments. Both calculations and experimental proved S and Mo doping promote the adsorption and dissociation of H 2 O molecule on FeOCl (010) surface with different process mechanisms. The surface electronegativity decreases slightly due to S doping, which reduces the repulsion to H 2 O molecule and lower the adsorption energy compared with clean surface. While, after forming stable adsorption structure, S doping promotes the dissociation of H 2 O by changing the electrons distribution in H 2 O and competing the shared electrons to weak the O–H bond strength. In contrast, Mo doping enhances the electropositivity of the surface, which is more conducive to the molecular adsorption reaction and more exothermic via coulombic attraction. For dissociative adsorption, the strength of O-H bond is enhanced, and the dissociation process is inhibited by Mo doping due to the electrons polarization in H 2 O molecule. Furthermore, S and Mo atoms are proved to be incorporated into the FeOCl lattice which enhance of H 2 O dissociation on doped FeOCl nanosheets surface. This study presents a microscopic insight for effects of S and Mo doped FeOCl surface on H 2 O molecule behaviors, while provides a theoretical basis for further research of the FeOCl surface water. [ABSTRACT FROM AUTHOR]

The incorporation of hazardous solid waste in fired bricks fabrication is a viable way. However, the physical and mechanical properties of products were negatively influenced due to the involvement of hazardous solid waste. Three fluxing agents, waste glass powder (WGP), Na-feldspar and K-feldspar, were introduced in this study to eliminate these negative influences. Physical and mechanical properties were tested by standard method. Microstructure and pore structure of bricks were conducted by Scanning Electron Microscopy (SEM) and nitrogen adsorption and desorption isotherm. The change in mineral phase was detected by X-Ray Diffraction (XRD). The leaching toxicity of heavy metals were carried out by Toxicity Characteristic Leaching Procedure (TCLP) and Netherlands tank leaching test. The introduction of fluxing agents can greatly promote effectively compressive strength and decline water absorption. When 30 wt% (weight percent) of fluxing agents are added, water absorption reduced by more than 50%, and compressive strength increased by more than one time. XRD and SEM analysis showed that fluxing agents can promote the formation of glass-ceramic phase, which were mainly formed by the self-melting reaction of fluxing agents and the interaction with silicon-aluminium oxides. These dense glass phases could reduce the porosity and promote the compactness of microstructure. The formation of glass-ceramic phases could also reduce the leachability risk of heavy metals. Combing with properties of brick and price of fluxing agents, WGP is considered to be more suitable for improving properties of fired bricks containing hazardous waste. This study could provide some useful parameters and knowledge for improving properties and leaching toxicity risk when hazardous wastes were utilized in the production of fired brick. Image 1 Fluxing agents can reduce water absorption substantially. Fluxing agents can promote compressive strength remarkably. Microstructure become homogeneous and dense due to fluxing agents Fluxing agents can decrease leachability of heavy metals [ABSTRACT FROM AUTHOR]

Cr(VI) compounds at high temperature usually tend to decompose and reduce into Cr(III) due to thermodynamically instability for Cr(VI). This study found Cr(VI) could be reduced into Cr(V) instead of Cr(III) in the presence of CaO during heating solid waste containing Cr(VI). CaCrO 4 is prepared and mixed with CaO as simulated solid waste containing Cr(VI). It was found that CaCrO 4 reacted with CaO and formed a new product Ca 5 (CrO 4) 3 O 0.5 at temperature range of 800 and 1000 °C. The valence state of Cr in Ca 5 (CrO 4) 3 O 0.5 is determined to be +5 b y XPS analysis, and the color for new formed Cr(V) is observed in green, similar to Cr(III) compounds. The temperature and CaO are two keys to arouse the reduction reaction of Cr(VI) into Cr(V). In particular, the reduction of Cr(VI) into Cr(V) is strongly depended on temperature (800–1000 °C), this reaction can be balanced within 10 min, while prolonging sintering time has little help for promoting the reduction of Cr(VI) to Cr(V). Additionally, it was found Cr(V) can keep stable and not be re-oxidized into Cr(VI) at 800–1000 °C. Above results offers some new understanding and knowledge about the formation of Cr(V) in presence of much CaO or CaCO 3 during heating solid waste containing Cr(VI). Image 1 • CaCrO 4 reacted with CaO at 900 °C and formed a new product Ca 5 (CrO 4) 3 O 0.5. • The reduction from Cr(VI) to Cr(V) can be finished in 10 min. • Ca 5 (CrO 4) 3 O 0.5 was not easy to be oxidized into Cr(VI) at 900 °C. • The temperature and CaO are two keys to the formation of Cr(V). [ABSTRACT FROM AUTHOR]

Progress has been made in developing the maternally inherited endosymbiotic bacterium Wolbachia as a tool for protecting humans from mosquito-borne diseases. In contrast, Wolbachia -based approaches have not yet been developed for the protection of plants from insect pests and their associated diseases, with a major challenge being the establishment of artificial Wolbachia infections expressing desired characteristics in the hemipterans that transmit the majority of plant viruses. Here, we report stable introduction of Wolbachia into the brown planthopper, Nilaparvata lugens , the most destructive rice pest that annually destroys millions of hectares of staple crops. The Wolbachia strain w Stri from the small brown planthopper, Laodelphax striatellus , was transferred to this new host, where it showed high levels of cytoplasmic incompatibility, enabling rapid invasion of laboratory populations. Furthermore, w Stri inhibited infection and transmission of Rice ragged stunt virus and mitigated virus-induced symptoms in rice plants, opening up the development of Wolbachia -based strategies against major agricultural pests and their transmitted pathogens. • The w Stri Wolbachia infection was stably established in Nilaparvata lugens (Stål) • Extremely high density of w Stri Wolbachia was observed in all examined tissues • High CI level ensures rapid spread of w Stri Wolbachia in laboratory populations • w Stri Wolbachia blocks rice virus transmission involving vector Nilaparvata lugens Gong et al. report the first successful transfer of a Wolbachia endosymbiont into a pest planthopper. The endosymbiont self-spreads into host populations and inhibits transmission of a rice plant virus by Nilaparvata lugens. The findings open the way for a new approach to limiting crop damage caused by agricultural pests. [ABSTRACT FROM AUTHOR]

• Larger diameter waste glass improve brick properties more effectively. • Larger diameter waste glass was easy to form molten glass–ceramic phase. • Smaller particle size waste glass tends to form crystalline quartz. • Larger diameter waste glass decreases environmental safety of brick. The introduction of industrial solid waste in fired clay brick is a promising way to consume this waste, however, physical and mechanical properties were seriously impacted due to the incorporation of these solid waste. In current study, various particle diameters of waste glass powder (WGP) were introduced in the preparation process of brick to examine the difference in improving physical and mechanical performances of products, and to obtain the optimal particle size of waste glass for applying in the preparation of fired brick. Results showed the incorporation of WGP in larger particle size (100 and 300 meshes) can effectively improve properties, like bulk density, water absorption and compressive strength, but decrease thermal conductivity slightly. XRD and SEM analysis revealed that WGP with particles size of 100 and 300 meshes would become glass–ceramic phase or form albite, which can improve effectively physical and mechanical properties. However, part of WGP with particle size of 600 and 800 meshes might melt and crystalize into quartz at high temperature. The addition of WGP in particle size of 100 and 300 meshes can decrease much leachability of heavy metals from fired bricks and promote environment safety comparing with WGP with particle size of 600 and 800 meshes. Above results suggested that there is no necessary to grind WGP in much smaller particle size during introduction of waste glass for improving fired brick property. The conclusions from this research give some useful information for the incorporation of WGP in the preparation of fired brick. [ABSTRACT FROM AUTHOR]