Good Recovery Properties Research Articles

Two Cd(Ⅱ)/Mn(Ⅱ) complexes based on multinuclear metal clusters for Fe(Ⅲ) and Cr(Ⅵ) fluorescence detection and magnetic properties

Two novel complexes, {[Cd3(L)2(H2O)2]·(H2O)4}n (1) and {[Mn(HL)(H2O)2]·(H2O)}n (2), which are synthesized by the reaction of 3-(2, 4-dicarboxyphenyl)-4-carboxypyridine ligand with cadmium and manganese metal ions under the solvothermal method. The complex 1 is a 3D framework based upon trinuclear [Cd3(μ2-COO)4(μ1-COO)4(N)2] SBUs, and the complex 2 is a one-dimensional metal oxygen chain based upon binuclear [Mn2(μ2-COO)2(μ1-COO)2(N)2] SBUs. The solid fluorescence analysis of complex 1 reveals that the emission peak of 451 nm when its excitation peak is 336 nm. The fluorescence detection experiments of complex 1 showed that Fe3+, Cr2O72− and CrO42− can effectively to be detected. Furthermore, their limits of detection are 1.47 × 10−3 M, 1.31 × 10−3 M and 1.25 × 10−3 M, respectively. It has good recovery properties as a potential multifunctional fluorescence sensor. Besides, the quenching mechanism of fluorescence sensing is also discussed. In addition, the magnetic studies of complex 2 show strong antiferromagnetic interactions between its neighboring Mn(II) ions.

Laboratory Evaluation of the Relationship of Asphalt Binder and Asphalt Mastic via a Modified MSCR Test

Asphalt mastic, which consists of an asphalt binder and a mineral filler, provides critical adhesion and viscoelasticity to an asphalt mixture. The rheological response of the asphalt mastic is mainly derived from its asphalt binder. In this study, a simple laboratory test method is proposed to estimate the relationship of asphalt binder and its mastic. Two modified binders (3.5% and 4.0% styrene–butadiene–styrene (SBS) of asphalt binder by mass) were blended with a limestone filler at six different mineral filler contents to produce mastic samples. A modified multiple stress creep-recovery (MSCR) test was conducted on both the asphalt binder and its mastic with the same testing protocols, and the stress conditions and rheological response of asphalt binder in the mastic with linear or nonlinear viscoelasticity were both investigated. The results show that the stress of the asphalt binder in its mastic decreased with increasing filler contents. However, for the linear-viscoelasticity mastic, the decrease rate of the stress began to slow down when the filler content had reached 100% or 120%. For the rheological properties of the asphalt binder in the mastic, the %R of the asphalt binder was improved by adding filler, especially for the nonlinear-viscoelasticity mastic. The asphalt binder of the linear-viscoelasticity asphalt mastic also showed a linear viscoelastic response and a good recovery property. The performance of the asphalt mastic and rheological properties of its asphalt binder were highly related to its filler content.

Fabrication and application of pickering emulsion stabilized by high pressure homogenization modified longan shell nanofiber

Food-grade Pickering emulsion have attracted extensively attention in food engineering applications. In this work, high pressure homogenization (HPH) was applied to modified the longan shell cellulose nanofiber (LSCNF). The obtained LSCNF was used as a naturally-derived particle stabilizer for O/W Pickering emulsions and the gel-based Pickering emulsions can be applied to baked foods to control the release of free fatty acid (FFA). The results showed that the HPH-modified LSCNF not only had higher viscosity, but also had enhanced interfacial properties. In addition, the emulsion stabilized by LSCNF showed a gel behavior and good recovery properties. Moreover, the use of emulsion as a fat replacement in biscuits could improve the texture of dough and inhibit the FFA release of biscuit during digestion. Our finding indicates that LSCNF is suitable to fabricate food-grade Pickering emulsions and it can be successfully used as a fat replacement in novel baked foods.

Alginate-Lysozyme Nanofibers Hydrogels with Improved Rheological Behavior, Printability and Biological Properties for 3D Bioprinting Applications.

In this study, alginate nanocomposite hydrogel bioinks reinforced with lysozyme nanofibers (LNFs) were developed. Alginate-LNF (A-LNF) suspensions with different LNF contents (1, 5 and 10 wt.%) were prepared and pre-crosslinked with 0.5% (w/v) CaCl2 to formulate A-LNF inks. These inks exhibit proper shear-thinning behavior and good recovery properties (~90%), with the pre-crosslinking step playing a crucial role. A-LNF fully crosslinked hydrogels (with 2% (w/v) CaCl2) that mimic 3D printing scaffolds were prepared, and it was observed that the addition of LNFs improved several properties of the hydrogels, such as the morphology, swelling and degradation profiles, and mechanical properties. All formulations are also noncytotoxic towards HaCaT cells. The printing parameters and 3D scaffold model were then optimized, with A-LNF inks showing improved printability. Selected A-LNF inks (A-LNF0 and A-LNF5) were loaded with HaCaT cells (cell density 2 × 106 cells mL−1), and the cell viability within the bioprinted scaffolds was evaluated for 1, 3 and 7 days, with scaffolds printed with the A-LNF5 bioink showing the highest values for 7 days (87.99 ± 1.28%). Hence, A-LNF bioinks exhibited improved rheological performance, printability and biological properties representing a good strategy to overcome the main limitations of alginate-based bioinks.

P-type Sb doping hierarchical WO3 microspheres for superior close to room temperature ammonia sensor

Nanosheet-assembled microspheres of tungsten oxide doped with antimony were synthesized via hydrothermal method. Sb doping changed the valency of W, promoted a partial crystal phase transition from orthorhombic to hexagonal, and modified the surface morphology. Further, WO3 is an n-type semiconductor and is sensitive to gases above 100 °C. The Sb-WO3 sensors in this work were p-type semiconductors from 25 °C to 65 °C, and exhibited excellent sensitivity, fast response and good recovery properties to NH3. At 35 °C, the detection limit of 1 at% Sb-WO3 for ammonia was 200 ppb, and the sensor shows a good stability and selectivity toward several possible interferent. The substantially improved sensing performance of the Sb-WO3 sensors at near room temperature could be mainly attributed to the change of the W valency promoted via Sb doping.

Nonprecious Bimetallic Sites Coordinated on N-Doped Carbons with Efficient and Durable Catalytic Activity for Oxygen Reduction.

Developing efficient, inexpensive, and durable electrocatalysts for the oxygen reduction reaction (ORR) is important for the large-scale commercialization of fuel cells and metal-air batteries. Herein, a hierarchically porous bimetallic Fe/Co single-atom-coordinated N-doped carbon (Fe/Co-Nx -C) electrocatalyst for ORR is synthesized from Fe/Co-coordinated polyporphyrin using silica template-assisted and silica-protection synthetic strategies. In the synthesis, first silica nanoparticles-embedded, silica-protected Fe/Co-polyporphyrin is prepared. It is then pyrolyzed and treated with acidic solution. The resulting Fe/Co-Nx -C material has a large specific surface area, large electrochemically active surface area, good conductivity, and catalytically active Fe/Co-Nx sites. The material exhibits a very good electrocatalytic activity for the ORR in alkaline media, with a half-wave potential of 0.86 V versus reversible hydrogen electrode, which is better than that of Pt/C (20 wt%). Furthermore, it shows an outstanding operational stability and durability during the reaction. A zinc-air battery (ZAB) assembled using Fe/Co-Nx -C as an air-cathode electrocatalyst gives a high peak power density (152.0 mW cm-2 ) and shows a good recovery property. Furthermore, the performance of the battery is better than a corresponding ZAB containing Pt/C as an electrocatalyst. The work also demonstrates a synthetic route to a highly active, stable, and scalable single-atom electrocatalyst for ORR in ZABs.

Nickel foam-supported Fe,Ni-Polyporphyrin microparticles: Efficient bifunctional catalysts for overall water splitting in alkaline media

Developing highly active, stable and sustainable electrocatalysts for overall water splitting is of great importance to generate renewable H2 for fuel cells. Herein, we report the synthesis of electrocatalytically active, nickel foam-supported, spherical core-shell Fe-poly(tetraphenylporphyrin)/Ni-poly(tetraphenylporphyrin) microparticles (FeTPP@NiTPP/NF). We also show that FeTPP@NiTPP/NF exhibits efficient bifunctional electrocatalytic properties toward both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Electrochemical tests in KOH solution (1 M) reveal that FeTPP@NiTPP/NF electrocatalyzes the OER with 100 mA cm−2 at an overpotential of 302 mV and the HER with 10 mA cm−2 at an overpotential of 170 mV. Notably also, its catalytic performance for OER is better than that of RuO2, the benchmark OER catalyst. Although its catalytic activity for HER is slightly lower than that of Pt/C (the benchmark HER electrocatalyst), it shows greater stability than the latter during the reaction. The material also exhibits electrocatalytic activity for overall water splitting reaction at a current density of 10 mA cm−2 with a cell voltage of 1.58 V, along with a good recovery property. Additionally, the work demonstrates a new synthetic strategy to an efficient, noble metal-free-coordinated covalent organic framework (COF)-based, bifunctional electrocatalyst for water splitting.

CRISPR-dCas9 powered impedimetric biosensor for label-free detection of circulating tumor DNAs

Label-free biosensors which can be integrated into lab-on-a-chip platforms have the advantage of using small volumes for rapid and inexpensive measurements contrary to label-based technologies which are often more costly and time-consuming. In this study, graphene oxide screen printed electrodes (GPHOXE) were modified by deactivated Cas9 (dCas9) proteins and synthetic guide RNA (sgRNA) as the biorecognition receptor for label-free detection of circulating tumor DNAs (ctDNA). This was achieved by detection of a tumor related mutation (PIK3CA exon 9 mutation) via sequence-specific recognition followed by electrochemical impedance spectroscopy (EIS) analysis. The biosensor showed high specificity as there was no impedance signal for other ctDNA sequences, even the single nucleotide mismatch. dCas9-sgRNA modified biosensor demonstrated linear detection limits between 2 and 20 nM for 120 bp ctDNA’s in 40 s. The calibration curve showed good linearity, LOD was calculated as 0.65 nM and LOQ was calculated as 1.92 nM. Selectivity and repeatability studies were carried out in real blood samples and the recovery was higher than 96%. In conclusion, dCas9-sgRNA was effectively immobilized and optimized on GPHOXE as the selective biorecognition receptor of this ultrafast impedimetric biosensor. The CRISPR-dCas9 powered impedimetric system showed good selectivity, high repeatability and good recovery properties. This is the first literature to report the use of CRISPR/Cas technology as a label-free tool that can be used in an impedimetric system for detection of ctDNA’s.

Injectable self-assembled bola-dipeptide hydrogels for sustained photodynamic prodrug delivery and enhanced tumor therapy

Supramolecular peptide materials have attracted increasing attention due to their natural biological origin and versatile applications. However, it is often challenging to control and modulate the self-assembly of peptides (especially short peptides) for constructing hydrogels with tunable mechanical properties and adaptive injectability toward biomedical applications. Here, we report a supramolecular strategy for forming robust and injectable hydrogels based on the self-assembly of a rationally designed bola-dipeptide. The self-assembled hydrogels exhibit versatile functionalities, including flow under shear stress, good recovery properties, and easy encapsulation of hydrophilic prodrugs. The prodrug-loaded hydrogels show sustained release profiles, inhibited nontargeted leakage, and enhanced localized prodrug conversion, leading to highly efficient photodynamic tumor ablation. Hence, the supramolecular strategy is promising for the rational construction of injectable hydrogels toward targeted and sustained prodrug conversion and tumor therapy.

ZnO-Al2O3 nanocomposite as a sensitive layer for high performance surface acoustic wave H2S gas sensor with enhanced elastic loading effect

ZnO-Al2O3 nanocomposite was synthesized and developed as a high performance sensitive and selective layer for surface acoustic wave (SAW) sensor, aiming for in-situ detection of H2S gas in ppb level operated at room temperature. ZnO-Al2O3 nanocomposite, synthesized though a sol-gel method, was spin-coated onto a quartz based SAW resonator. This composite layer inherits the mesoporous structure of the Al2O3 layer and good affinity to H2S gas molecules of the ZnO layer, and thus can selectively adsorb and react with H2S gas molecules to form ZnS compounds on its surface. This reaction leads to significant decreases of both pore sizes and total pore volume of the layer, an increase of layer’s elastic modulus, thus causing a large positive shift of the frequency responses of the SAW sensor. The sensor operated at room temperature shows a frequency response of ∼500 Hz to 10 ppb H2S, with an excellent selectivity and good recovery property.

Study on surface relief related to reverse martensitic transformation in Mn-based high-temperature antiferromagnetic shape memory alloy

Evolution of surface relief and its intrinsic mechanism associated with martensitic transformation (MT) during heating and cooling in Mn79.5Fe15.6Cu4.9 high-temperature antiferromagnetic shape memory alloy (SMA) have been investigated in nano-scale by means of in-situ atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic mechanical analyzer (DMA). Experimental results show that the N-type surface relief originates from the reverse MT and is completely made of matrix which is different from the conventional ones. The reverse MT exhibits untwinning shear and the reverse shearing of twinned martensites mainly contribute to the surface relief. The measured surface relief angles are less than 1°, which are determined by the small difference of lattice constants between fcc and fct structures. Surface relief has a good recovery property because of the crystallographic reversibility rule in SMAs, implying that this kind of alloy has a good surface morphology memory effect.

Azithromycin: assessment of intrinsic cytotoxic effects on corneal epithelial cell cultures

PurposeTo compare the cytotoxic effects of preservative-free azithromycin on corneal epithelial cells in vivo with those of preservative-free netilmicin and levofloxacin, and the preservative benzalkonium chloride (BAK).MethodsRabbit corneal epithelial cells in vitro were incubated for 15 minutes or 6 hours with commercially available ophthalmic preservative-free netilmicin 0.3%, levofloxacin 0.3%, or azithromycin 1.5% preparations or different concentrations of unpreserved azithromycin and different concentrations of BAK. Qualitative analysis was undertaken using phase-contrast optics to examine the morphological aspects of cell cultures and quantitative analysis was undertaken by measuring the release of the cytoplasmic enzyme lactate dehydrogenase into the medium immediately and 24 hours after exposure to drugs. Finally, we observed the wound-healing rate of mechanically injured corneal epithelial cells exposed to each antibiotic ophthalmic preparation for 48 hours.ResultsOur results show that both the commercially available unpreserved mono-dose preparation of azithromycin and ophthalmic preparations of azithromycin up to a concentration of 1.5% were virtually devoid of harmful effects under our experimental conditions. This was not significantly different from the results obtained for the other antibiotic preparations (P > 0.05) tested, but was unlike the results obtained for BAK. Azithromycin 1.5% also showed good recovery properties after a mechanical wound test.ConclusionUnder our experimental conditions, unpreserved azithromycin 1.5% showed a much lower toxicity than BAK and did not interfere with the wound-healing process.

Low Temperature Catalytic Steam Gasification of Waste Palm Trunk by Pottasium Carbonate Supported on Perovskite Oxide

A waste palm trunk was used as raw materials of derived biochar in catalytic steam gasification experiments. Pre-treatment was done to enrich the carbon content and removed the heavy and light tar. Waste palm trunk has been added in pyrolysis reactor to produce biochar at temperature 550°C under N2 flow. The experimental ran in a bubbling fluidized reactor at atmospheric pressure by the steam as gasification agent and Nitrogen as a carrier gas with different catalysts such as K2CO3 / LaMn0.8Cu0.2, K2CO3 / Alumina, Alumina and K2CO3 respectively. The experiments have been carried out to investigate the effect of gasification temperature, effect of catalyst and effect of catalyst ratio to biochar on the carbon conversion into syngas. The syngas compositions were analyzed by gas chromatography. K2CO3 / LaMn0.8Cu0.2 catalyst showed the better carbon conversion as compared to the other catalysts. Perovskite oxide was more effective as a support for the gasification catalyst. The results showed that the better carbon conversion ratio within short time gasification and removed heavy and light tar. K2CO3 / LaMn0.8Cu0.2 showed high activity for biochar gasification at low temperature and good recovery property near 750°C.

Immobilization of Penicillin G Acylase on Magnetic Nanoparticles Modified by Ionic Liquids

Functionalized ionic liquids containing ethyoxyl groups were synthesized and immobilized on magnetic silica nanoparticles (MSNP) prepared by two steps, i.e., Fe3O4 synthesis and silica shell growth on the surface. This magnetic nanoparticle supported ionic liquid (MNP-IL) were applied in the immobilization of penicillin G acylase (PGA). The MSNPs and MNP-ILs were characterized by the means of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). The results showed that the average size of magnetic Fe3O4 nanoparticles and MSNPs were ∼10 and ∼90 nm, respectively. The saturation magnetizations of magnetic Fe3O4 nanoparticles and MNP-ILs were 63.7 and 26.9 A·m−2·kg−1, respectively. The MNP-IL was successfully applied in the immobilization of PGA. The maximum amount of loaded enzyme was about 209 mg·g−1 (based on carrier), and the highest enzyme activity of immobilize PGA (based on ImPGA) was 261 U·g−1. Both the amount of loaded enzyme and the activity of ImPGA are at the same level of or higher than that in previous reports. After 10 consecutive operations, ImPGA still maintained 62% of its initial activity, indicating the good recovery property of ImPGA activity. The ionic liquid modified magnetic particles integrate the magnetic properties of Fe3O4 and the structure-tunable properties of ionic liquids, and have extensive potential uses in protein immobilization and magnetic bioseparation. This work may open up a novel strategy to immobilize proteins by ionic liquids.

Low‐temperature route to thermoplastic polyamide elastomers

AbstractThermoplastic polyamide elastomers were obtained by polymerization of aminobenzoyl‐substituted telechelics derived from poly(tetrahydrofuran)‐diols (number‐average molecular weight: 1400 or 2000 g mol−1) with several diacid dichlorides (terephthaloyl dichloride, 4,4′‐biphenyldicarbonyl dichloride, or 2,6‐naphthalenedicarbonyl dichloride) and chlorotrimethylsilane in N,N‐dimethylacetamide at 0–20 °C. The as‐prepared polymers had melting temperatures above 190 °C and exhibited elastic properties at room temperature, as evidenced by dynamic mechanical analysis and stress–strain measurements. The polymer with 2,6‐naphthalenedicarboxamide hard segments had the widest rubbery plateau within the series, the highest extension at break, and good recovery properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1449–1460, 2004

A versatile two-phase trigger circuit

A trigger circuit with good recovery properties is described. It may be used as a gate generator, delayed gate generator, fast coincidence circuit, or frequency divider.