Cyclic Utilization Research Articles

A Novel Process for the Synthesis of Highly Pure n-3 Polyunsaturated Fatty Acid (PUFA)-Enriched Triglycerides by Combined Transesterification and Ethanolysis

In this study, a novel two-step enzymatic reaction was developed for the synthesis of highly pure triacylglycerols (TAGs) with a high content of n-3 polyunsaturated fatty acids (PUFAs). Glyceride mixtures were primarily synthesized by Novozym 435-catalyzed transesterification of glycerol and DHA/EPA-rich ethyl esters (EEs), followed by removal of partial glycerides, for the first time, by immobilized mono- and diacylglycerol lipase SMG1-F278N-catalyzed ethanolysis. TAG yield as high as 98.66% was achieved under the optimized conditions, and highly pure (98.75%) n-3 PUFA-enriched TAGs with 88.44% of n-3 PUFA was obtained after molecular distillation at lower temperature (140 °C). In addition, the EEs produced during ethanolysis had a FA composition similar to that of the original EEs, making them feasible for cyclic utilization. This was the first study reporting removal of partial glycerides by ethanolysis. Through ethanolysis, a higher purity product could be easily obtained at a relatively low temperature compared with the conventional high-temperature molecular distillation.

Perfect entanglement concentration of an arbitrary four-photon polarization entangled state via quantum nondemolition detectors

We show how to concentrate an arbitrary four-photon polarization entangled state into a maximally entangled state based on some quantum nondemolition detectors. The entanglement concentration protocol (ECP) resorts to an ancillary single-photon resource and the conventional projection measurement on photons to assist the concentration, which makes it more economical. Our ECP involves weak cross-Kerr nonlinearities, X homodyne measurement and basic linear-optical elements, which make it feasible in the current experimental technology. Moreover, the ECP considers cyclic utilization to enhance a higher success probability. Thus, our scheme is meaningful in practical applications in quantum communication.

Self-healing, Reshaping, and Recycling of Vulcanized Chloroprene Rubber: A Case Study of Multitask Cyclic Utilization of Cross-linked Polymer

To develop a new technology for sustainable application of sulfur cross-linked rubbers, a novel latent catalyst, organic complex copper(II) methacrylate (MA-Cu), is explored to trigger disulfide metathesis at elevated temperature. When it is incorporated into vulcanized chloroprene rubber fabricated following industrial recipe, reshuffling of inherent sulfur cross-links is enabled typically at 120 °C, while microstructure of the material remains unchanged at lower temperature (typically lower than 100 °C). Such a latent character of MA-Cu is believed to ensure operation stability of the rubber under ambient conditions, and its organic nature helps to improve dispersion homogeneity. By taking advantage of the activated cross-linked networks, the sulfur bonds can be reversibly exchanged inside the vulcanized chloroprene rubber as well as across the surfaces at 120 °C. As a result, the rubber is coupled with the capabilities of repeated reshaping, self-healing, and recycling without need of changing its macr...

Hierarchical nanostructures of BiOBr/AgBr on electrospun carbon nanof ibers with enhanced photocatalytic activity

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Silver nanoparticles supported on electrospun polyacrylonitrile nanofibrous mats for catalytic applications

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Mild synthesis of biofuel over a microcrystalline S2O82 −/ZrO2 catalyst

A solid super acid catalyst, S2O82−/ZrO2, was prepared by a new synthesis route of one-pot method with ammonium persulfate via vapor phase hydrolysis to improve biodiesel production using expired soybean oil as reactant. Catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and NH3-temperature programmed desorption (NH3-TPD) to determine the optimum pretreatment conditions and understand the role of the active sites for transesterification. S2O82−/ZrO2 calcined at 500°C, which showed an amorphous phase by XRD characterization, was identified as composed of tetragonal phase ZrO2 microcrystallites by TEM examination. The microcrystallites which anchored more S2O82− had abundant super acid and displayed high catalytic activity in the transesterification under mild reaction conditions. The reaction parameters over the catalyst were optimized and both the conversion of soybean oil and selectivity of biofuel reached 100% under the conditions of 110°C of reaction temperature, 4h of reaction time and 20:1 of methanol to oil molar ratio. Moreover, the catalyst showed high stability in the reactions and no sulfur leaching was found in the biodiesel products in cyclic utilization.

“Waking sleeping beauty”: Regeneration of vulcanized rubber by triggering dynamicity of the inherent sulfur network

society, which causes severe impact on environment in the meantime. This is because there are no proper disposals of the scraps, which are full of infusible and insoluble crosslinked networks. So far, methods have been developed to convert waste rubbers into small molecular weight fragments with commercial value, or granules as fillers of thermoplastics and asphalt. In some cases, the used rubber products are simply burned and buried. The bad resource management leads to significant pollution accordingly (DOI: 10.3144/expresspolymlett.2016.17). When reviewing vulcanized rubber, we can find that the key technique of fabrication, i.e. vulcanization, remains nearly unchanged since the invention of Goodyear about two hundred years ago. The cross linked networks contain tremendous disulfide and polysulfide bonds. Recent investigation indicates that metathesis of disulfide enables self-healing of polymers. In this context, so long as disulfide metathesis among different disulfide and polysulfide bonds can be triggered in sulfur crosslinked networks, the vulcanized rubber would acquire self-healability and recyclability. In a patented invention, tiny amount of catalysts (CuCl2 and copper(II) methacrylate) are incorporated into polybutadiene and chloroprene rubber, which are then compounded with the usual fillers and curatives following industrial formulation. The preliminary results (DOI: 10.1039/c5gc00754b and DOI: 10.1021/ acssuschemeng.6b00224) show that the catalysts can effectively initiate metathesis of disulfide bonds, so that the inherent sulfur crosslinks of the vulcanized rubbers are allowed to be dynamically rearranged and reshuffled at 110~120°C. It means that the sulfur crosslinks are as stable as the version excluding the catalysts under conventional circumstances without fear of loosing stability during service at lower temperature (typically below 110°C). More importantly, by taking advantage of the activated cross linked networks, the vulcanized rubbers can be repeatedly selfhealed, reshaped, and recycled in solid phase at 110~120°C without environmentally unfriendly decrosslinking. Additionally, mechanical properties of the healed and recycled materials approach to those of the original version. The catalysts do not react with the other additives in the matrix and do not accelerate aging of the rubbers. The availability of self-healing, reshaping and reprocessing of vulcanized rubber offers new possibilities of cyclic utilization. Different circulation loops can be selected by various combinations of the smart functionalities according to actual demand. Life cycle of rubbers would thus be extended, while waste of resources is reduced. There maybe other ‘sleeping beauties’ like the above in everyday life, which are waiting for being waked.

Immobilization and Characterization of Penicillin G Acylase (PGA) Immobilized on Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ Nanoparticles.

Magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles were prepared via the solution combustion process and their microstructure and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The as-prepared magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles are characterized with average grain size of about 20 nm and magnetization of 90.3 Am²/kg. The surface of magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles was modified by use of sodium silicate and N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, and the penicillin G acylase (PGA) was successfully immobilized on the surface-modified magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles. The results show that the activity for the immobilized PGA is affected less by pH and temperature than that for the free PGA, and the immobilized PGA exhibits a high effective activity, good stability of enzyme catalyst. This immobilized PGA on magnetic Ni₀.₅Zn₀.₅Fe₂O₄ nanoparticles can be separated from the solution by the external magnetic field for cyclic utilization, and they could retain about 70% of initial enzyme activity after 11 consecutive operations. The kinetic parameters (Km and Vmax) were determined, and the value of Km for the immobilized PGA (204.53 mmol/L) is higher than that of the free enzyme (3.50 mmol/L), while Vmax (1.93 mmol/min) is also larger than that of the free enzyme (0.838 mmol/min).

Cyclic utilization of HP-β-CD in the bioconversion of cortisone acetate by Arthrobacter simplex.

To establish a method for the recovery and reutilization of hydroxypropyl-β-cyclodextrin (HP-β-CD) to lower the cost of its industrial application in cortisone acetate bioconversion. HP-β-CD is not degraded by Arthrobacter simplex CPCC140451 (ASP) resting cells and 96.4 % HP-β-CD could be recovered by isobutyl acetate extraction. Moreover, the inclusion ability of recovered HP-β-CD barely decreased. The saccharide metabolic and catalytic activities of ASP were greater in the aqueous phase after extracting with isobutyl acetate than other organic solvents. Cyclic utilization tests showed that cortisone acetate conversion ratio was 91.0 % after eight cycles and reached 95.7 % with 0.2-0.6 mM HP-β-CD. Furthermore, >90 % conversion ratio was reached per cycle through a co-cyclic-utilization method with HP-β-CD and immobilized ASP. Cortisone acetate conversion ratio in the HP-β-CD cyclic-utilization method is promising for industrial applications. The method can also be expanded to other CDs and other hydrophobic compounds bioconversion.

Solvent-assistant self-assembly of an AIE+TICT fluorescent Schiff base for the improved ammonia detection

Solvent-assistant self-assembly of an AIE+TICT fluorescent Schiff base into one-dimensional nanofilaments has been developed. The orientation of the assemblies can be controlled by a simple dewetting process: the filaments are interweaved when the self-assembly process is performed on a horizontal substrate, while tilting the substrate to a tiny angle results in the formation of highly oriented ones with long-range order as verified by microscopic examination. The compound shows remarkable fluorescent response to ammonia gas based on a TICT-LE transition. The self-assembled film presents higher detection sensitivity compared with the non-assembled test paper: the former enables 4.75 times faster response time and 6.86 times lower detection limit than the latter. Furthermore, the former demonstrates better selectivity toward ammonia gas in the presence of various organic amines. The sensing devices also enjoy the advantage of cyclic utilization. The fluorescence of the fumed devices can be converted back into the original state when they are heated at 100°C for 5min, as thermal treatment can desorb the ammonia gas that adsorbed in the sensing devices.

Study on the stress characteristic and fatigue life of the shredder pin

The hammer shredder is the key equipment for cyclic utilization of retired car bodies. The axes' pin is the main component of the shredder, but it is damaged easily. To improve the shredding efficiency and lengthen the changing life of the shredder pin, it is significant to study its stress characteristic and the fatigue life. In this article, the complex force conditions of the shredder pin at the normal working condition were studied briefly by mechanics analysis method. The stress characteristics and fatigue life of the pin were analyzed by the finite element transient analysis method. The maximum stress distribution law of the shredder pin was found and the fracture mechanism of the retired car bodies was revealed. Furthermore, the reliability of the simulation results was verified by the experiment. It was found that when the pin rotates around the main shaft counterclockwise, the maximum stress of the pin at 0° of the main shaft is higher than other positions. Additionally, along the axial direction, the maximum stress occurs at the cross section at a distance of 2/9 of the pin length from the pin head and at 0° of this section, which orientation is made when the pin is at 270° of the main shaft. Comparing four working modes, it was found that the working life of the shredder pin could be doubled by changing the sides of the pin and rotate it along its axes by 180°.

Reusable and dual-potential responses electrogenerated chemiluminescence biosensor for synchronously cytosensing and dynamic cell surface N-glycan evaluation.

A novel reusable and dual-potential responsive electrogenerated chemiluminescence (ECL) biosensor was fabricated for synchronous detection of cancer cells and their surface N-glycan. In this strategy, a cancer cell recognized aptamer hybridized with a capture DNA was immobilized on electrochemically reduced MoS2 nanosheets, and Ru(phen)3(2+) as ECL probes was intercalated into the grooves of the double-strand DNA. In the presence of target cells, the capture DNA and Ru(phen)3(2+) were released from the electrode interface owing to the specific interaction between cancer cells and the aptamer. Meanwhile, concanavalin A (Con A), a mannose binding protein, and a conjugated gold nanoparticle modified graphite-C3N4 (Con A@Au-C3N4) was used as a negative ECL nanoprobe and applied for the cell surface N-glycan evaluation owing to the excellent ECL properties of g-C3N4 at negative potential. The cytosensing and cell surface N-glycan evaluation could be simultaneously realized with high sensitivity and excellent selectivity based on the ratio of ECL intensity between the negative potential and positive potential (ΔECLn/ΔECLp), avoiding the traditional routing cell counting procedures. Moreover, the aptamer modified electrode can be regenerated in the presence of capture DNA solutions for cyclic utilization. As a proof-of-concept, the ECL cytosensor showed excellent performances for the analysis of the MCF-7 cancer cell and its surface N-glycan evaluation in human serum samples. The reusable and dual potential response ECL biosensor endows a feasibility tool for clinical diagnosis and drug screening especially in complex biological systems.

Facile fabrication of highly flexible graphene paper for photocatalytic reduction of 4-nitrophenol

Freestanding paper-like materials prepared from chemically derived graphene have considerable potential as a carbon-based catalyst in high-performance flexible catalytic reaction. Herein, a highly flexible graphene paper (GP) assembled from graphene oxides (GOs) with the aid of polyacrylamide (PAA) and electroless deposition of gold nanoparticles (AuNPs) was prepared. In contrast to previous reports on GOs based on a flow-directed assembly of graphene sheets, this GOs/PAA/Au composite paper exhibited a highly wrinkled and disordered morphology. The resultant GOs/PAA/Au composite paper was applied as a catalytic material for the reduction of 4-nitrophenol and showed the favour separation, recovery and cyclic utilization properties.

Switchable Spherical-Wormlike Micelle Transition in Sodium Oleate/N-(3-(Dimethylamino)propyl)-Octanamide Aqueous System Induced by Carbon Dioxide Stimuli and pH Regulation

The structure transitions of the aggregates in the sodium oleate (NaOA)/N-(3-(dimethylamino)propyl)-octanamide (DPOA) aqueous system was investigated upon CO2 stimuli. During the process of bubbling of CO2, three appearance states of sol, gel, and emulsion with little white precipitate were observed continuously. The cryo-transmission electron microscope characterization and rheological measurements exhibited that the sol–gel transition was attributed to a spherical-wormlike micelle transition. Moreover, this transition was switchable at least three cycles in the pH range of 10.91–9.56 by CO2 stimuli and pH regulation (adding NaOH), which could be explained by the protonation of DPOA and deprotonation of DPOA · H+. Bubbling of CO2 resulted in protonation of DPOA, which not only inserted into the OA– as a co-surfactant but also screened the electrostatic repulsion among OA–, corporately leading to the spherical-wormlike micelle transition. Adding NaOH caused the deprotonation of DPOA · H+ and hence reversed this transition. This surfactant system with switchable micelle transition not only displays tremendous application potential in various fields but also is of key importance in cyclic utilization of surfactant.

Screening of Coagulant for Washing Wastewater Treatment

According to the problems exist in cyclic utilization of washing wastewater, the coagulation tests utilizing ferric trichloride (FeCl3), alums, poly aluminium chloride (PAC) and polyacrylamide (PAM) are studied, respectively. Experimental results show that PAC was much better than the other coagulants in the removal of LAS and chroma as a single coagulant. Cast 2.5mL PAC(10%) into quantitative washing wastewater, the removal rate of LAS and chroma reach 82.5% and 87.8%, respectively. When mix the every two kinds of coagulants, maintaining the same total amount of coagulant to 2.5mL, cast1.0mL PAC(10%) and 1.5mL alum (10%) into washing wastewater ,the removal rate of LAS and chroma reach 84.1% and 90.0%, respectively.

Eco-Packaging Solution for Express Service in the Era of Online Shopping

With the development of the internet and the increase in people’s consumption level, online shopping has become increasingly popular with the boom in the online shopping having contributed directly to the rapid development of the whole express industry, which is now experiencing the surge in the business to make the number of the packing bags consumed in the express industry increased at a geometric rate. However at present, the following situations have occurred in Chinese logistical packaging industry: (1) excessive packaging and repeated packaging; (2) the environmental pollution caused by the packing material; (3) the low cyclic utilization rate of the packaging.

New insight into modulated up-conversion luminescent silica nanotubes as efficient adsorbents for colored effluents.

We report a simple and easy method to fabricate silica nanotubes (SNTs) with multicolor up-conversion luminescence by single-nozzle electrospinning based on phase separation effect without any templates. Multicolor up-conversion nanoparticles (UCNPs) were first synthesized by a similar hydrothermal route. Then, the water solution containing NPs were added slowly into the electrospinning precursor solution in a dropwise manner. After electrospinning process and calcination at 600 °C, pure SNTs with uniformly dispersed NPs were obtained. The as-produced up-conversion (UC) luminescent SNTs were used as an adsorbent for the removal of colorful dye from aqueous solutions. Adsorption experiments indicated that the SNTs have good adsorption capacity and that the adsorption amount can be traced by two indicators: the decrease in UV adsorption of the solutions and changes in the UC intensity of the SNTs. More importantly, the UC-SNT adsorbents are piece-like and could be effectively and quickly separated via filtration or centrifugation. Furthermore, the SNTs can regenerate by calcination and retain almost the same absorption capability for recycling use. Considering cost, function and cyclic utilization, UCNPs decorated SNTs may create a new platform for the preconcentration and separation of colored pollutants from waste water.

Effect of Hg in Jiaozhou Bay Waters - Aquatic Transfer Process

Based on the investigation data of Hg in Jiaozhou Bay waters in April, July and October 1986, this paper tried to analysis the horizontal, vertical and seasonal distributions of Hg in Jiaozhou Bay, and to reveal the pollution sources and transfer processes of Hg. Results showed that Jiaozhou Bay had been heavily polluted by Hg, whatever in different seasons. Hg in Jiaozhou Bay was mainly from point sources such as industrial waste and sewage runoff. The horizonal and vertical distributions of Hg content showed the transfer processes as, from estuaries to their outside and the bay mouth, and form surface waters to bottom waters, respectively. The water environmental capacity of Hg in Jiaozhou Bay had been unable to carry the emission load of Hg, and therefore the reduction of emission as well as the improvement of cyclic utilization ratio were the primary processes for Hg pollution prevention and reduction.

Cr (VI) removal by a new type of anion exchange resin DEX-Cr: Adsorption affecting factors, isotherms, kinetics, and desorption regeneration

The adsorption of Cr (VI) by an anion exchange resin of DEX-Cr, which contains tertiary and quaternary amine groups, was studied under varying experimental conditions that include pH, resin amount, contact time, and temperature. Batch-shaking experiments were conducted to evaluate the performance of DEX-Cr in removing Cr (VI). The ion-exchange process indicated that the maximum removal could be achieved at pH of 3 and an initial Cr (VI) concentration of 2200 mg/L. The results of adsorption equilibrium experiments fit well with Freundlich isotherm, showing that the adsorption was a multilayer process. Thermodynamic parameters indicated that the uptake of Cr (VI) by DEX-Cr was spontaneous and endothermic. Kinetic experimental data followed the pseudo first-order equation. The desorption study revealed that adding NaCl to NaOH solution helped to improve elution efficiency dramatically. The elution results had a relationship with the mass fraction of NaCl to NaOH, higher mass fraction contributed to higher elution efficiency. The elution efficiency improved slightly with the number of times of desorption increasing, which indicates that the resin had potential in cyclic utilization. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 387–393, 2015

“Flower-Like” PA6@Mg(OH)2 electrospun nanofibers with Cr (VI)-removal capacity

Abstract Hexavalent chromium (Cr (VI)) is a kind of high toxic pollutant which is harmful to marine organisms as well as humanity. Removal of Cr (VI) from water is a hot-spot in environmental remediation. In this work, PA6@Mg(OH) 2 composite nanofibrous membrane was fabricated by electrospinning technique combined with hydrothermal strategy. The as-prepared nanofibrous membrane possesses a flower-like structure of which endows not only novel morphology but also increase the specific surface area of electrospun fibers. Owing to the 2D flower-like structure of which increase the specific surface area of the nanofibers, the Cr (VI) adsorption capacity from water can be as high as 296.4 mg per gram of nanofibrous membrane (when the concentration of Cr (VI) is 110 mg/g), which is much higher than the most ever reported research results. Meanwhile, the freestanding membrane can be easily separated from liquid solutions and shows excellent cyclic utilization performance. Therefore, such novel flower-like nanofibrous membrane can be potentially widely used in environmental remediation.