Comparison of cytotoxicity of Ag/ZnO and Ag@ZnO nanocomplexes to human umbilical vein endothelial cells in vitro.

Novel metal and metal oxide-based nanocomplexes are being developed due to their superior properties compared with nanoparticles (NPs) based on single composition. In this study, we synthesized Ag-coated ZnO (Ag/ZnO) and Ag-doped ZnO (Ag@ZnO) NPs. The cytotoxicity and mechanisms associated with the synthesized NPs were investigated to understand the influence of Ag positions on biocompatibility of the NPs. After exposure to human umbilical vein endothelial cells (HUVECs), Ag/ZnO, Ag@ZnO, and ZnO NPs all significantly induced cytotoxicity, but the cytotoxic effects of Ag/ZnO and Ag@ZnO NPs were more modest in comparison with ZnO NPs. At cytotoxic concentrations, all NPs significantly induced intracellular Zn ions, which suggested a role of excessive Zn ions on cytotoxicity of NPs. All types of NPs significantly induced the expression of endoplasmic reticulum (ER) stress genes including DNA damage-inducible transcript 3 (DDIT3), X-box binding protein 1 (XBP-1), and ER to nucleus signaling 1 (ERN1), but Ag/ZnO and Ag@ZnO NPs were less effective to induce DDIT3 and XBP-1 expression compared with ZnO NPs. Not surprisingly, only ZnO NPs significantly induced the expression of caspase 3. Combined, the results from this study showed that Ag/ZnO and Ag@ZnO NPs were less cytotoxic and less potent to induce ER stress gene expression compared with ZnO NPs, but there were no significant differences between Ag/ZnO and Ag@ZnO NPs. Our results may provide novel understanding about the biocompatibility of Ag-ZnO nanocomplexes.

Cu(I)/TF-BiphamPhos-catalyzed asymmetric Michael addition of cyclic ketimino esters to alkylidene malonates.

Cu(I)-catalyzed asymmetric Michael addition of cyclic ketimino esters with alkylidene malonates has been developed for efficient construction of ß-branched α-amino acids containing adjacent quaternary and tertiary stereogenic centers in good yields with excellent diastereo-/enantioselectivities. The generated Michael adduct was further converted to the biologically important pyrrolizidine analogues via one-pot sequential reduction/lactamization.

Synthesis of lipophilic vitamin C and evaluation of its antioxidant performance in sunflower seed oil frying.

The present study involved the synthesis and analysis of a lipophilic form of vitamin C, namely tetrabutyryl vitamin C ester (TVCE). TVCE is synthesized by a simple one-step method, combining the advantages of VC and butyric acid. Its antioxidant efficacy on sunflower seed oil frying was evaluated by assessing lipid oxidation parameters including peroxide number (POV), carbonyl number (CV), and paraniline number (pAV). Furthermore, changes in the fatty acid composition of the oil were monitored using techniques such as infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and gas chromatography (GC). The findings demonstrated that lipophilic vitamin C exhibited superior protection against oxidation during frying compared to vitamin E, suggesting that it may be an effective fat-soluble antioxidant. The study provides a new field for the utilization of vitamin C and a new idea for the development of efficient antioxidants.

Influence of wastewater discharge from dredging mariculture pond sediments on the food sources of two intertidal crab species.

The present study δ13C, δ15N and fatty acid compositions of two dominant mangrove crabs, Tubuca arcuata and Parasesarma plicatum were compared between a mangrove site frequently receiving dredged wastewater from mariculture ponds and an adjacent reference site, to investigate the impact of wastewater discharge on their diets. A laboratory experiment was also conducted to further test how their diets changed with the wastewater input. The result showed no significant change in the δ13C while clear 15N enrichment of crabs in association with the wastewater discharge. Changes in 15N signature and fatty acid composition of the crabs due to the wastewater discharge indicated that the impact of wastewater discharge was related to crab species, being more apparent on the deposit feeder (T. arcuata) than the herbivorous P. plicatum. The results suggested that the discharge of dredged wastewater into mangroves resulted in the uptake of wastewater-derived materials and nutrients by mangrove crabs.

One-step removal of hexavalent chromium in wide pH range using thiourea dioxide: the role of reactive species.

One-step removal of hexavalent chromium in a wide pH range is of great significance. In this paper, a single thiourea dioxide (TD) and two-components thiourea dioxide/ethanolamine (MEA) were used as a green reducing agent for the efficient removal of Cr(vi), respectively. The reduction of Cr(vi) and the precipitation of Cr(iii) were carried out simultaneously under this reaction system. The experimental results proved that TD was activated by amine exchange reaction with MEA. In other words, MEA promoted the generation of an active isomeride of TD by changing the equilibrium position of the reversible reaction. After adding MEA, the removal rate of Cr(vi) and total Cr could reach industrial water discharge standards in a wide pH range of 8-12. The change of pH, reduction potential and the decomposition rate of TD were investigated in the reaction processes. Meanwhile, reductive and oxidative reactive species were produced simultaneously during this reaction process. Further, oxidative reactive species (O2˙- and 1O2) were beneficial for the decomplexation of Cr(iii) complexes and the formation of Cr(iii) precipitation. The experimental results also demonstrated that TD/MEA was effective in practical industrial wastewater. Hence this reaction system has a significant industrial application prospect.

Synthesis of lipoic acid ferulate and evaluation of its ability to preserve fish oil from oxidation during accelerated storage.

Lipoic acid ferulate (LAF) was synthesized and its anti-free radical ability in vitro was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS) assays. Protective effects of LAF in stabilizing fish oil were tested, compared to antioxidants such as lipoic acid, ferulic acid and tert-butylhydroxyquinone (TBHQ) by measuring peroxide values, thiobarbituric acid reactants, p-anisidine values, nuclear magnetic resonance (NMR) spectra and gas chromatography-mass spectrometry (GC-MS) spectra of fish oil during accelerated storage (12 days, 80 °C). The inhibitory effect of these antioxidants on fish oil oxidation followed the order TBHQ ≧ LAF > ferulic acid > lipoic acid. In addition, the omega-3 polyunsaturated fatty acids were the first to be oxidized. The formation of oxidation products followed a first-order kinetic model, and the addition of LAF effectively reduced the reaction rate constants. Therefore, LAF can effectively slow down the formation of oxidative products and prolong the shelf life of fish oil.

Effect of Al Layer Thickness on the Bonding and Mechanical Behavior of a Mg-(Al-)Ti Laminated Sheet Prepared by Hot-Rolling after Differential Preheating Treatment.

Mg-(Al-)Ti laminated sheets with large bonding interfaces were prepared by a differential temperature hot-rolling process, in which the preheating treatment of Ti was 25-100 °C higher than that of Mg. The rolled sheets contained different Al layer thicknesses (≤0.05 mm), and the thickness of the diffused region at the interface of 3-7 µm was formed by rolling at 175 °C. The interfaces were the solid-solution regions of Mg(Al) and Ti(Al), and no intermetallic compounds were generated during both the rolling process and annealing treatment. The hardness of the interfaces was 16-30% greater than that of the Mg matrix and Ti matrix. The results of mechanical tests displayed that the Mg-(Al-)Ti sheets exhibited higher strength and elastic modulus compared to those of the rolled AZ31B sheet. Their UTS and YTS were about 223-460 MPa and 303-442 MPa, respectively, with an elongation of 0.04-0.17 and high elastic modulus of 52-68 GPa. The Mg-Ti (containing about 62 at.% Mg) rolled sheet exhibited the most excellent strength. The UTS and YTS were about 460 MPa and 442 MPa, with an elongation of 0.04 and elastic modulus of 61.5 GPa. Additionally, Mg-Ti sheets with thin Ti thickness possessed a higher work-hardening rate (n), as well as hardening rate, than the rolled Mg-Al-Ti sheets. This is because fractured Ti pieces around the interfaces have a significant strengthening effect. This study provides a simple method for fabricating Mg-(Al-)Ti sheets with high elastic modulus.

Ultrafine platinum nanoparticles supported on N,S-codoped porous carbon nanofibers as efficient multifunctional materials for noticeable oxygen reduction reaction and water splitting performance.

The design of highly active, stable and durable platinum-based electrocatalysts towards the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and hydrogen adsorption has a high and urgent demand in fuel cells, water splitting and hydrogen storage. Herein, ultrafine platinum nanoparticles (Pt NPs) supported on N,S-codoped porous carbon nanofibers (Pt-N,S-pCNFs) hybrids were prepared through the electrospinning method coupled with hydrothermal and carbonation processes. The ultrafine Pt NPs are sufficiently dispersed and loaded on pCNFs and codoped with N and S, which can improve oxygen adsorption, afford more active sites, and greatly enhance electron mobility. The Pt-N,S-pCNFs hybrid achieves excellent activity and stability for ORR with ∼70 mV positive shift of onset potential compared to the commercial Pt/C-20 wt% electrocatalyst. The long-term catalytic durability with 89.5% current retention after a 10 000 s test indicates its remarkable ORR behavior. Pt-N,S-pCNFs also exhibits excellent HER and OER performance, and can be used as an efficient catalyst for water splitting. In addition, Pt-N,S-pCNFs exhibits an excellent hydrogen storage capacity of 0.76 wt% at 20 °C and 10 MPa. This work provides novel design strategies for the development of multifunctional materials as high-performance ORR catalysts, water splitting electrocatalysts and hydrogen storage materials.

Microstructure and mechanical properties of the Mg-Gd-Zn alloy prepared by sintering of rapidly-solidified ribbons.

Mg-15Gd-1Zn (wt.%) alloy was successfully prepared via the spark plasma sintering rapid solidification ribbons process. Microstructure investigation showed that the sintered alloys consisted of fine grains, the ß1 phase, and long-perioded stacking ordered phase (LPSO). The sintering temperature and time have a significant effect on the microstructural evolution. A lower sintering temperature (430 °C ) was beneficial for obtaining finer grain sizes with less than 5 µm and a higher content of ß1 phase with a content of 3-15 vol.% and a size-distribution of (10-600) nm. A higher temperature for a longer sintering time, 450-470 °C and 5-10 min, helpfully promoted precipitating the abundantly lamellar LPSO phase, and its content was 2-10 vol.% for LPSO phase with the width of (10-100) nm. The mechanical properties indicated that the fine grain size and supersaturated solid solution contributed at least 50% of the yield stress, and the residual contribution was related to the ß1 phase and LPSO phase strengthening, which were based on their contents and the sizes.

Decorating UiO-66-NH2 crystals on recyclable fiber bearing polyamine and amidoxime bifunctional groups via cross-linking method with good stability for highly efficient capture of U(VI) from aqueous solution.

Although polyacrylonitrile fiber (PANF) and metal-organic frameworks (MOFs) have been extensively investigated to remove U(VI) from water, their practical applications are seriously hindered by the relatively low stability of PANF in acidic solution and great difficulty of separating MOFs nanoparticles from solution, beside that, little attention is paid to the fabrication of MOFs and PANF composite materials (MPCMs) with excellent adsorption capacity for U(VI). Herein, we report the synthesis of novel MPCMs by decorating different concentrations of UiO-66-NH2 crystals onto polyamine and amidoxime groups functionalized PANF (PA-AO-PANF) through cross-linking method for U(VI) extraction. The characterization results reveal that the combination of PA-AO-PANF and UiO-66-NH2 crystals endows MPCMs with excellent separation ability, large surface area, good stability and plentiful surface functional groups, which contributes to good selectivity and enhanced adsorption performance. Consequently, the obtained UN-PA-AO-PANF-2 shows the maximum uptake capacity of 441.8 mg/g and equilibrium uptake time of 30 min towards U(VI). Besides, the U(VI) uptake ability and structure of UN-PA-AO-PANF-2 are well preserved after ten adsorption-desorption cycles. With these outstanding properties, the adsorbent has great potential for the capture of U(VI) from aqueous solutions. Importantly, this work provides a cost-effective and efficient way to construct extremely stable MPCMs hybrid fibers.

Synthesis of rice husk-based ion-imprinted polymer for selective capturing Cu(II) from aqueous solution and re-use of its waste material in Glaser coupling reaction.

With the deepening of the concept of recycling economy and green chemistry, selective capture of Cu(II) from wastewater by biosorbent and reuse of the spent Cu(II)-loaded adsorbent are of great significance. Herein, we synthesized composite of rice husk (RH) with mesoporous silica MCM-41 (RH@MCM-41) modified by organosilane containing amino and schiff groups as functional monomer and cross-linking agent. The silica modified RH@MCM-41 was employed as supporter to fabricate copper ion-imprinted polymers as absorbents (named as RM-CIIPs) via surface ion imprinting technique. Adsorption isotherms, kinetics, selectivity and mechanism of RM-CIIPs to remove Cu(II) were investigated with respect to different adsorption condition. Furthermore, we explored the catalytic activity of spent Cu(II)-loaded adsorbent in Glaser coupling reaction. Batch adsorption studies revealed that RM-CIIP-3 prepared with functional monomer shows the best adsorption capacity (91.4 mg/g) for Cu(II), and adsorption equilibrium could be reached within 30 min. RM-CIIP-3 exhibited an excellent selectivity for capturing Cu(II) and reusability in six adsorption/desorption cycles. More importantly, the spent Cu(II)-loaded adsorbent could be used as bio-heterogeneous catalyst and afford the desired product (1,4-diphenylbutadiyne) in 99.1% yield. Our research indicates an eco-friendly systematic strategy to utilize the waste material as an adsorbent for removing heavy metals and catalyst for industry.

1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP)-Assisted Catalyst-Free Sulfonation of Allylic Alcohols with Sulfinyl Amides.

A highly regioselective and catalyst-free sulfonation of allylic alcohols with sulfinyl amides has been realized. Such a mix-and-go procedure provides a convenient approach to synthetically various allylic sulfones under mild reaction conditions. Furthermore, this novel reaction shows ample substrate scope and outstanding functional group tolerance and could also be scaled-up. Meanwhile, it is the first example that sulfinyl amides act as a powerful sulfur nucleophile in the reactions. 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) as a solvent plays a critical role in allylic sulfonation.

A facile Cu(I)/TF-BiphamPhos-catalyzed asymmetric approach to unnatural α-amino acid derivatives containing gem-bisphosphonates.

A novel catalytic asymmetric Michael addition of azomethine ylide with ß-substituted alkylidene bisphosphates was realized in the presence of a chiral copper(I)/TF-BiphamPhos complex. The present system provides a unique and facile access to enantioenriched unnatural α-amino acid derivatives containing gem-bisphosphonates (gem-BPs) in high yields with excellent diastereoselectivities and enantioselectivities. Subsequent transformations lead to the expedient preparation of biologically active unnatural α-amino acid derivatives containing BPs and bisphosphonic acids without loss of diastereo- and enantiomeric excess.

Asymmetric construction of 3-vinylidene-pyrrolidine derivatives containing allene moiety via Ag(I)/TF-BiphamPhos-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with diethyl 2-(3,3-diphenylpropa-1,2-dienylidene) malonate.

Catalytic asymmetric 1,3-dipolar cycloaddition of various azomethine ylides with diethyl 2-(3,3-diphenylpropa-1,2-dienylidene)malonate has been developed successfully with good to excellent enantioselectivity for the effcient construction of 3-vinylidene-pyrrolidine derivatives containing a unique allene moiety.

Catalytic asymmetric 1,3-dipolar cycloaddition of N-unprotected 2-oxoindolin-3-ylidene derivatives and azomethine ylides for the construction of spirooxindole-pyrrolidines.

Asymmetric 1,3-dipolar cycloaddition of N-unprotected 2-oxoindolin-3-ylidene with azomethine ylides for the construction of spirooxindole-pyrrolidines bearing four contiguous stereogenic centers has been achieved with AgOAc/TF-BiphamPhos complexes for the first time. This catalytic system performance well over a broad scope of substrates, providing the synthetically useful adducts in high yields and excellent diastereoselectivities and moderate enantioselectivities.

Uniformly dispersed platinum nanoparticles over nitrogen-doped reduced graphene oxide as an efficient electrocatalyst for the oxygen reduction reaction.

Oxygen reduction reaction (ORR) with efficient activity and stability is significant for fuel cells. Herein, platinum (Pt) nanoparticles dispersed on nitrogen-doped reduced graphene oxide (N-rGO) were prepared by a hydrothermal and carbonized approach for the electrocatalysis of ORR. Polyvinylpyrrolidone plays a significant role in the reduction and dispersion of platinum particles (about 2 nm). The obtained Pt-N-rGO hybrids exhibited superior activity with an electron transfer number of ∼4.0, onset potential 0.90 eV of ORR, good stability and methanol tolerance in alkaline media. These results reveal the interactions between Pt-N-rGO and oxygen molecules, which may represent an oxygen modified growth in catalyst preparation. The excellent electrocatalysis may lead to the decreased consumption of expensive Pt and open up new opportunities for applications in lithium air batteries.

Li-fluorine codoped electrospun carbon nanofibers for enhanced hydrogen storage.

Carbon materials have attracted increasing attention for hydrogen storage due to their great specific surface areas, low weights, and excellent mechanical properties. However, the performance of carbon materials for hydrogen absorption is hindered by weak physisorption. To improve the hydrogen absorption performance of carbon materials, nanoporous structures, doped heteroatoms, and decorated metal nanoparticles, among other strategies, are adopted to increase the specific surface area, number of hydrogen storage sites, and metal catalytic activity. Herein, Li-fluorine codoped porous carbon nanofibers (Li-F-PCNFs) were synthesized to enhance hydrogen storage performance. Especially, perfluorinated sulfonic acid (PFSA) polymers not only served as a fluorine precursor, but also inhibited the agglomeration of lithium nanoparticles during the carbonization process. Li-F-PCNFs showed an excellent hydrogen storage capacity, up to 2.4 wt% at 0 °C and 10 MPa, which is almost 24 times higher than that of the pure porous carbon nanofibers. It is noted that the high electronegativity gap between fluorine and lithium facilitates the electrons of the hydrogen molecules being attracted to the PCNFs, which enhanced the hydrogen adsorption capacity. In addition, Li-F-PCNFs may have huge potential for application in fuel cells.

Versatile 3D reduced graphene oxide/poly(amino-phosphonic acid) aerogel derived from waste acrylic fibers as an efficient adsorbent for water purification.

The fabrication of multifunctional materials to remove soluble heavy metal ions and dyes, as well as insoluble oils from waste water is urgently required, yet remains a daunting challenge because of difficulty in controlling their structure and property to satisfy various demands. Herein, for the first time, novel 3D reduced graphene oxide/poly(amino-phosphonic acid) (PAPA) aerogels (rGO/PAPAs) with different PAPA content were developed by solvothermal reduction of the graphene oxide and cross-linking with PAPA chain, and subsequently employed as versatile adsorbent for the removal of complex pollutants such as Cr(III) ion, methylene blue (MB) dye and various kinds of organic solvents from water. Benefiting from the synergistic effect of the reduced graphene oxide (rGO) sheet and PAPA component, as well as its unique 3D structure, the resultant aerogel (rGO/PAPA-2) gained amphiphilic, ultralight, and multifunctional properties. Thus, it showed a fast adsorption rate (within 15 min) and high adsorption capacity (up to 327.1 mg/g) for Cr(III) ion at an optimal pH of 5.5 due to its unique 3D network structure with abundant amino-phosphonic acid functional groups. The uptake of Cr(III) by rGO/PAPA-2 was fitted well with the Langmuir isotherm and pseudo-second-order kinetic model. The adsorption mechanism of Cr(III) onto rGO/PAPA-2 can be attributed to electrostatic attraction and surface complexation with APA groups. In addition, the rGO/PAPA-2 displayed an excellent adsorption performance for MB (694.5 mg/g) and several organic solvents (83.2 to 254.3 g/g). Moreover, the rGO/PAPA-2 exhibited a good regeneration (around 99%) and satisfactory recovery abilities for the tested adsorbates. Notably, PAPA chains can be easily prepared from waste acrylic fibers, making it become a cost effective but versatile candidate to prepare new material. Therefore, this work provides a new design strategy to fabricate the rGO/PAPA-2 aerogel with great prospect for sophisticated industrial wastewater cleanup.

A Novel Design to Enhance the Mechanical Properties in Cu-Bearing Antibacterial Stainless Steel.

A novel method based on nano-scale precipitation hardening has been studied to strengthen copper-bearing ferrite antibacterial stainless steel. Bimodal precipitations can be observed after antibacterial annealing and low temperature aging treatment, which are large rod-shaped precipitates and nano-sized spherical precipitates, respectively. Due to two different morphological precipitates, the strength of the material is significantly improved without sacrificing formability, and at the same time, the excellent antibacterial properties remain. Under low temperature aging treatment, there is no obvious evidence to show the segregation at the interface between the rod-shaped copper precipitation and the matrix due to the low segregation coefficient of copper. The nano-sized copper precipitation uniformly nucleated and distributed on the matrix. The optimized heat treatment process is antibacterial annealing at 800 °C for half an hour followed by one-hour-aging treatment at 550 °C.

Utilization of gibberellin fermentation residues with swine manure by two-step composting mediated by housefly maggot bioconversion.

The ecological disposal of gibberellin fermentation residues (GFRs) is urgently needed. This study explored a new method of direct GFR utilization with swine manure at different substitution proportions (0%, 20%, 40%, and 60%) using two-step composting mediated by housefly maggot bioconversion. Regarding maggot bioconversion, substitution of GFRs accelerated the temperature increase and water content decrease, slowed the pH increase, and enhanced the maggot conversion rate. Among the proportions, 20% GFR substitution had the highest maggot conversion rate of 15.15%. During the composting stage, GFR substitution promoted the initial temperature increase and the water content decrease and maintained a relatively low pH. However, only 20% substitution promoted the maturity of compost. The degradation rates of the gibberellin residue were all higher than 97% in the treatments with GFRs after two-step composting. High-throughput sequencing analysis showed that GFR substitution had significant effects on the microbial community structure during the whole process. However, the change in the microbial community was similar to that of conventional composting. Therefore, this innovative approach is feasible for GFR resource utilization, and substitution below 20% for swine manure is recommended.