Construction of NiCoZnS materials with controllable morphology for high-performance supercapacitors.

A facile two-step hydrothermal approach with post-sulfurization treatment was put forward to construct the mixed transition metal sulfide (NiCoZnS) with a high electrochemical performance. The different morphologies of NiCoZnS materials were successfully fabricated by adjusted the Ni/Co molar ratio of the NiCoZn(OH)F precursor. Moreover, thein situphase transformation from the NiCoZn(OH)F phase to Zn0.76Co0.24S and NiCo2S4phases and lattice defects via the S2-ion-exchange were determined by x-ray diffractometer, transmission electron microscopy and x-ray photoelectron spectroscopy techniques, which improved electric conductivity and interfacial active sites of the NiCoZnS, and so promoted the reaction kinetics. Significantly, the urchin-like NiCoZnS1/1prepared at the Ni/Co molar ratio of 1.0 exhibited promising electrochemical performances with high capacitance and excellent cycling stability. Furthermore, the asymmetric device (NiCoZnS//AC) using NiCoZnS1/1as the positive electrode had excellent supercapacitor performances with an energy density of 57.8 Wh·kg-1at a power density of 750 W·kg-1as well as a long cycle life (79.2% capacity retention after 10 000 cycles), indicating the potential application in high-performance supercapacitors.

Controllable architecture of the NiCoZnS@NiCoFe layered double hydroxide coral-like structure for high-performance supercapacitors.

The rational design of the morphological structure of electrode materials is considered as an important strategy to obtain high-performance supercapacitors. So, NiCoZnS materials with different Ni/Co/Zn molar ratios on Ni foam (NF) were synthesized, in which the Ni/Co/Zn molar ratio plays a key role in the morphological structure and electrochemical performances. Furthermore, the pre-prepared NiCoZnS materials act as substrates to guide the self-assembling of NiCoFe layered double hydroxide (LDH) nanosheets on the substrate surface to form core-shell electrode materials (NiCoZnS@NiCoFe-LDH) with a 3D mesoporous hierarchical network structure for further improving electrochemical performances. The unique interconnected coral-like NiCoZnS1@NiCoFe-LDH with a large specific surface area (93.1 m2 g-1) and high specific capacitance is achieved at the Ni/Co/Zn molar ratio of 1 : 1 : 1. Benefiting from the unique structural feature and respective merits of the NiCoZnS and NiCoFe-LDH, the NiCoZnS1@NiCoFe-LDH demonstrates an ultrahigh specific capacitance of 1524.0 C g-1 (3386.7 F g-1) at 1.0 A g-1 and excellent 95.0% capacitance retention at 10 A g-1 after 5000 cycles. As for practical application, the assembled NiCoZnS1@NiCoFe-LDH//AC delivers a favorable energy density of 66.25 W h kg-1 at 1500 W kg-1 and a long-term cycling lifetime (86.04% retention at 5.0 A g-1 after 10 000 cycles), which suggests promising potential in energy storage and conversion.

Enhanced efficiency in isolation and expansion of hAMSCs via dual enzyme digestion and micro-carrier.

A two-stage method of obtaining viable human amniotic stem cells (hAMSCs) in large-scale is described. First, human amniotic stem cells are isolated via dual enzyme (collagenase II and DNAase I) digestion. Next, relying on a culture of the cells from porous chitosan-based microspheres in vitro, high purity hAMSCs are obtained in large-scale. Dual enzymatic (collagenase II and DNase I) digestion provides a primary cell culture and first subculture with a lower contamination rate, higher purity and a larger number of isolated cells. The obtained hAMSCs were seeded onto chitosan microspheres (CM), gelatin-chitosan microspheres (GCM) and collagen-chitosan microspheres (CCM) to produce large numbers of hAMSCs for clinical trials. Growth activity measurement and differentiation essays of hAMSCs were realized. Within 2 weeks of culturing, GCMs achieved over 1.28 ± 0.06 × 107 hAMSCs whereas CCMs and CMs achieved 7.86 ± 0.11 × 106 and 1.98 ± 0.86 × 106 respectively within this time. In conclusion, hAMSCs showed excellent attachment and viability on GCM-chitosan microspheres, matching the hAMSCs' normal culture medium. Therefore, dual enzyme (collagenase II and DNAase I) digestion may be a more useful isolation process and culture of hAMSCs on porous GCM in vitro as an ideal environment for the large-scale expansion of highly functional hAMSCs for eventual use in stem cell-based therapy.

Preparation of a NiAl-Oxide@Polypyrrole Composite for High-Performance Supercapacitors.

A core-shell NiAlO@polypyrrole composite (NiAlO@PPy) with a 3D "sand rose"-like morphology was prepared via a facile in situ oxidative polymerization of pyrrole monomer, where the role of PPy coating thickness was investigated for high-performance supercapacitors. Microstructure analyses indicated that the PPy was successfully coated onto the NiAlO surface to form a core-shell structure. The NiAlO@PPy exhibited a better electrochemical performance than pure NiAlO, and the moderate thickness of the PPy shell layer was beneficial for expediting the electron transfer in the redox reaction. It was found that the NiAlO@PPy5 prepared at 5.0 mL L-1 addition amount of pyrrole monomer demonstrated the best electrochemical performance with a high specific capacitance of 883.2 F g-1 at a current density of 1 A g-1 and excellent capacitance retention of 91.82 % of its initial capacitance after 1000 cycles at 3 A g-1 . The outstanding electrochemical performance of NiAlO@PPy5 were due to the synergistic effect of NiAlO and PPy, where the uniform network-like PPy shell with the optimal thickness made electrolyte ions more easily accessible for faradic reactions. This work provided a simple approach for designing organic-inorganic core-shell materials as high-performance electrode materials for electrochemical supercapacitors.

Optimization of ZnAl/Chitosan Supra-Nano Hybrid Preparation as Efficient Antibacterial Material.

The menace of antimicrobial resistance continues to increase and hence the need to discover new antibiotics, especially alternative and effective sources such as hybrid organic-inorganic, organic-organic materials, and other combinations. In this study, an antimicrobial hybrid supra-nano material was prepared by the bi-titration synthesis method of chitosan (CS) and ZnAl layered double hydroxide. Fourier-transform infrared spectrometer (FTIR), thermogravimetric and differential thermal gravimetric (TGA/DTG), ultraviolet-visible (UV-Vis), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses indicated that the ZnAl/CS hybrid exhibited low crystallinity with high thermal stability. The results of ZnAl/CS characterization showed the characteristic properties of the individual components ZnAl and CS, indicating a successful preparation of the ZnAl/CS hybrid. The antibacterial tests revealed that the ZnAl/CS hybrid possessed an enhanced antimicrobial effect against both Escherichia coli (E. coli, MTCC 739) and Penicilliumcyclopium (P. cyclopium, AS 3.4513). Under the central composite design (CCD) of the response surface methodology (RSM) tool, the parameters of the hybrid synthesis reaction were optimized and the result obtained was as follows: reaction pH was 11.3, reagent Zn/Al ratio was 3.27, and chitosan concentration was 1.07 g/L. After optimization, it was found that the antibacterial activity of ZnAl/CS was strengthened against E. coli as evidenced by a widening of the inhibition zone of about 41.6%. The antibacterial activity of ZnAl/CS was mainly due to the reactivation of the antibacterial activity of CS associated with the release of Zn2+ and Al3+ metal ions in addition to ZnO, Al2O3, and ZnAl2O4 compounds resulting from the method of preparation.

Preparation of the Hybrids of Hydrotalcites and Chitosan by Urea Method and Their Antimicrobial Activities.

Hybrid nano-supra molecular structured materials can boost the functionalityof nano- or supra-molecular materials by providing increased reactivity and conductivity, or by simply improving theirmechanical stability. Herein, the studies in materials science exploring hybrid systems are investigated from the perspective of two important related applications: healthcare andfood safety.Interfacing phase strategy was applied, and ZnAl layered double hydroxide-chitosan hybrids, prepared by the urea method (U-LDH/CS), were successfully synthesized under the conditions of different chitosan(CS) concentrations with a Zn/Al molar ratio of 5.0. The structure and surface properties of the U-LDH/CS hybrids were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectrometer(FTIR), scanningelectronmicroscopy(SEM), ultravioletvisible(UV-Vis), and zero point charge (ZPC) techniques, where the effect of CS concentration on the structure and surface properties was investigated. The use of the U-LDH/CS hybrids as antimicrobial agents against Escherichia coli, Staphylococcus aureus,and Penicilliumcyclopiumwasinvestigated in order to clarify the relationship between microstructure and antimicrobial ability. The hybrid prepared in a CS concentration of 1.0 g∙L-1 (U-LDH/CS1) exhibited the best antimicrobial activity and exhibited average inhibition zones of 24.2, 30.4, and 22.3mm against Escherichia coli, Staphylococcus aureus, and Penicilliumcyclopium, respectively. The results showed that the appropriate addition of CS molecules could increase antimicrobial ability against microorganisms.

Microwave Pretreatment and Enzymolysis Optimization of the Lotus Seed Protein.

Pretreatment with a microwave was conducted before enzymolysis and shown to enhance the enzymolysis, which changed the secondary structure of the lotus seed protein. Under high-power microwave irradiation, sub bonds of the protein were broken, causing disaggregation and unfolding of the secondary structure, namely a decrease in the intermolecular aggregate structure and increase in the random coil structure, making the protein bonds susceptible to papain in the enzymolysis. On the other hand, a response surface methodology (RSM) was launched to investigate the influence of the enzymolysis process variables on the DH (degree of hydrolysis). The statistical analysis revealed that the optimized conditions were a protein substrate concentration of 15 g/L, pH of 5.5, enzymolysis temperature of 57 °C, papain amount of 0.5 g/L, and enzymolysis time of 45 min, for which the predicted value of the DH was 35.64%. The results indicated that a microwave also had better potential for applications in the enzymolysis of foods.