Effects of carbonization temperature and time on the characteristics of carbonized sludge.

To investigate the influence of carbonization process parameters on the characteristics of municipal sludge carbonization products, this study selected carbonization temperatures of 300-700 °C and carbonization times of 0.5-1.5 h to carbonize municipal sludge. The results showed that with an increase in temperature and carbonization time, the sludge was carbonized more completely, and the structure and performance characteristics of the sludge changed significantly. Organic matter was continuously cracked, the amorphous nature of the material was reduced, its morphology was transformed into an increasing number of regular crystalline structures, and the content of carbon continued to decrease, from the initial 52.85 to 38.77%, while the content of inorganic species consisting continued to increase. The conductivity was reduced by 87.8%, and the degree of conversion of salt ions into their residual and insoluble states was significant. Natural water absorption in the sludge decreased from 8.13 to 1.29%, and hydrophobicity increased. The dry-basis higher calorific value decreased from 8,703 to 3,574 kJ/kg. Heavy metals were concentrated by a factor of 2-3, but the content of the available state was very low. The results of this study provide important technological support for the selection of suitable carbonization process conditions and for resource utilization.

Src kinase mediates coelomocytes phagocytosis via interacting with focal adhesion kinase in Vibrio splendidus challenged Apostichopus japonicus.

Immune cells have many efficient ways to participate in the host immunity, including phagocytosis, which is an important pathway to eliminate pathogens. Only ß-integrin-mediated phagocytosis pathways have been confirmed in Apostichopus japonicus. The Src family kinases (SFKs), a class of non-receptor tyrosine kinases plays an important role in the regulation of phagocytic signals in invertebrates. However, the SFK-mediated phagocytic mechanism is largely unknown in A. japonicus. In this study, a novel SFK homologue (AjSrc) with a conservative SH3 domain, an SH2 domain, and a tyrosine kinase domain was identified from A. japonicus. Both gene and protein expression of AjSrc and phosphorylation levels increased under Vibrio splendidus challenged, reaching the highest level at 24 h. Knock-down of AjSrc could depress coelomocytes' phagocytosis by 25% compared to the control group. To better understand the mechanism of AjSrc-mediated phagocytosis, focal adhesion kinase (FAK) was identified by a Co-immunoprecipitation experiment to be verified as an interactive protein of AjSrc. The phagocytosis rates of coelomocytes were decreased by 33% and 37% in AjFAK and AjSrc + AjFAK interference groups compared with the control group, respectively. Furthermore, the phosphorylation level of AjFAK was increased and reached the maximum level at 24 h post V. splendidus infection, as the same as that of AjSrc. Our results suggested that AjSrc could mediate V. splendidus-induced coelomocytes' phagocytosis via interacting with AjFAK and co-phosphorylation. This study enriched the mechanism of phagocytosis in echinoderm and provided the new theoretical foundation for disease control of sea cucumber.

Preparation of a hydrophobically associated cationic polyacrylamide and its regulation of the sludge dewatering performance.

A hydrophobically associating cationic polyacrylamide (HACPAM) was prepared by using a micellar polymerization method with V-50 (azobisisobutyramidine hydrochloride) as the initiator and acrylamide, acryloyloxyethyl trimethylammonium chloride and butyl methacrylate as substrates under ultraviolet light irradiation. Structural analysis using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance and X-ray photoelectron spectroscopy analyses showed that the substrates were successfully polymerized. HACPAM was used to condition sludge to improve its dewatering performance, and the results showed that as the amount of HACPAM increases, the sludge dewatering performance is significantly improved, and 3.532 kg/t dry solids of HACPAM is regarded as the optimal amount. Compared with the commercially available cationic polyacrylamide (CPAM), HACPAM has a stronger hydrophobic group association effect, with better promotion of the conversion of bound water in sludge flocs into free water, thereby improving the sewage dewatering performance. The 3D spatial structure of dewatered sludge cakes analyzed by computed tomography technology showed that the number of pores of the dewatered sludge cake treated by HACPAM 3 was smaller than that of the cake treated by CPAM, with a reduction in the porosity of 68.8%, resulting in a better hydrophobic effect. In addition, the mechanism of HACPAM improving the dewatering performance is discussed.

Experimental Investigation on the Wear and Damage Behaviors of Machined Wheel-Rail Materials under Dry Sliding Conditions.

Rail grinding and wheel turning can effectively remove surface defects and unevenness, which is a crucial process for the safe and smooth operation of trains. Machined surface integrity of wheel/rail materials significantly influences their tribological property. In this study, firstly, the rail blocks were ground via a cylindrical grinding machine, and the wheel rings were turned by a computer numerical control (CNC) lathe with varied parameters. Then, the sliding wear and damage characteristics of the machined wheel/rail samples under dry conditions were studied by virtue of a block-on-ring tribometer. The results show that the surface microhardness of the ground rail blocks is larger than that of wheel rings, while the surface roughness and the thickness of the subsurface plastic deformation layer (SPDL) of rail blocks are much smaller than those of wheel rings. After sliding, the surface microhardness of wheel/rail samples increases remarkably. The thickness of the SPDL, the wear loss, and the increase degree of surface microhardness of rail blocks are larger than those of wheel rings. Surface microhardness, roughness and the SPDL of the machined wheel/rail samples impose a combined influence on the anti-wear property, and the tribological pair with proper initial surface roughness and microhardness engenders the smallest amount of total wear loss.

Preparation of acrylamide and carboxymethyl cellulose graft copolymers and the effect of molecular weight on the flocculation properties in simulated dyeing wastewater under different pH conditions.

In this study, graft copolymers with different graft ratios (GRs) and molecular weights (MWs) were prepared by water bath polymerization using acrylamide (AM) and carboxymethyl cellulose (CMC) as substrates; additionally, the best preparation parameters were provided. The MW of the copolymer was inversely correlated with the GR (R = -0.82). The obtained graft copolymer was characterized by FTIR, 1H NMR, XPS and DSC. The results showed that CMC and AM were successfully copolymerized and the thermal stability of the product is improved. The graft copolymers with different MWs were used to flocculate a simulated dyeing wastewater at pH values of 3, 5, 7, 9 and 11. The results showed that as the molecular weight of the graft copolymers increased, the average flocculation settling ratio decreased drastically from 61.2% to 19.4% at pH 3, and the higher the MW, the better the flocculation settling performance. But the average settling ratio increased sharply at pH 11, and the increase grew from 21.0% to 50.3%. The larger the MW, the more obvious the decrease in flocculation sedimentation performance. The supernatant turbidity was reduced from 13324 NTU to less than 150 NTU, and the turbidity removal ratio exceeded 99%. The flocculation mechanism was discussed.

Theoretical study of the prohibited mechanism for ethylene/vinyl acetate co-polymers to the wax crystal growth.

To understand the effect of pour point depressants (PPD) on the wax growth is important for designing PPD additives for use with different oils with high efficiency and good economics. In our current study, molecular mechanics, molecular dynamics, and quantum mechanics calculations were performed to investigate the prohibited mechanism of ethylene/vinyl acetate (EVA) additives on the paraffin deposition in oils. On the wax surface, a single C18 molecule and clusters were preferably deposited on the wax surface (010) in a parallel conformation, which resulted in the formation of large blocks of wax crystal. MD simulation indicated that the linear conformation of EVA was more favorable to be adsorbed onto the carbon backbone of the wax surface (010) with the polar fragments of vinyl acetate staying upside of the surface. Furthermore, four EVA molecules can efficiently optimize the inhibition effect for the deposition of the solute C18 molecules over 10x8 size wax surface (010). According to the simulation results, a simplified rational model was established to estimate the minimum dosage of EVA-type PPD for fuels with different paraffin contents. In a certain degree, this simplified model has provided an effective route to correlate microstructures and the properties of polymer-involving systems, which will shed light on the application of theoretical studies in industries.

Immunogenic analysis of two DNA vaccines of avian reovirus mediated by attenuated Salmonella typhimurium in chickens.

Avian reovirus (ARV) is an important pathogen in poultry industry and causes great economic losses. As attenuated Salmonella typhimurium is already being used as an effective vehicle for the transfer of DNA vaccines, so in this study we evaluated two DNA vaccines mediated by S. typhimurium on their ability of eliciting antibody production. SPF chickens were respectively immunized with SL7207 (pVAX-σB), SL7207 (pVAX-σC) and SL7027 (pVAX-σB-σC) three times. The results showed that the antibody production was highly dependent on the immunizing times, detectable antibodies of serum antibody IgG and small intestinal mucosal antibody IgA were generated at week 4 and were further improved at week 6 and antibody titers in group SL7207 (pVAX-σC) were higher than that in group SL7207 (pVAX-σB), demonstrating that SL7207 (pVAX-σC) was more powerful than SL7207 (pVAX-σB) in antibody production. The higher antibody titer in SL7027 (pVAX-σB-σC) than that in SL7207 (pVAX-σC) group showed that co-expressing σB and σC could improve antibody production. IFN-γ detection showed that significant higher IFN-γ was generated both in groups SL7027 (pVAX-σB-σC) and SL7207 (pVAX-σC). Subsequent challenge showed that SL7207 (pVAX-σB), SL7207 (pVAX-σC) and SL7027 (pVAX-σB-σC) conferred 50%, 75% and 87.5% respectively.

Immunogenicity of a DNA vaccine of Avian Reovirus orally delivered by attenuated Salmonella typhimurium.

This study aimed to assess the ability of a Salmonella typhimurium-mediated Avain Reovirus DNA vaccine in eliciting antibody production. Six-day-old SPF chickens were orally immunized with SL7207 (pVAX-σC) twice at 2-week interval, detectable antibody was generated 2 weeks after immunization and was significantly higher than the control groups (P<0.01) and ten chickens (66.7%) were considered safe in the subsequent challenge. These results show that SL7207 (pVAX-σC) can induce protective antibody in chickens and the newly-constructed vaccine is also effective in protection chickens against ARV infection.