季铵型改性壳聚糖的制备及其在兔毛织物抗菌整理中的应用

以三乙胺和环氧氯丙烷为原料,合成醚化剂3-氯-2-羟丙基三乙基氯化铵。以甲壳素为原料通过醚化反应合成了季铵型甲壳素（CCT）,再经脱乙酰得到季铵型阳离子改性壳聚糖（CCTS）。采用红外光谱（FTIR）、核磁碳谱（¹³C NMR）对其化学结构进行了表征,运用黏度法和分光光度法测定了黏均分子量和溶解性等理化性能。采用最小抑菌法对CCTS的抗菌活性进行了测定,得到其对大肠杆菌的最低有效抑菌浓度（MIC）为0.2g/L,优于天然壳聚糖的MIC值。以柠檬酸为交联剂、次磷酸钠为催化剂,用CCTS对兔毛织物进行抑菌整理,考察织物经整理的抑菌效果和耐洗性。经5次洗涤后结果表明,CCTS对大肠杆菌的抑菌率达99.9%以上,抑菌率高于CCT和天然壳聚糖,是一种针对动物毛织物良好的天然高分子长效抑菌整理剂。     

Phase transition and interface evolution of Al2O3/ZrO2 particles in plasma-sprayed coatings

Alumina and zirconia ceramic particles exhibit high hardness and excellent wear resistance at high temperature, and hence are used as ceramic reinforcement phases in some plasma sprayed coatings. In this study, the interface evolution of a zirconia/alumina eutectic ceramic and the phase transition of zirconia in a plasma-sprayed coating were investigated. Scanning electron microscopy and transmission electron microscopy combined with focused-ion beam and energy dispersive X-ray were used to analyze the microstructure and composition of the ceramic interface. The results showed that the eutectic ceramic particles consisted of alumina (outer) and columnar zirconia (inner) before and after the plasma spraying process. The inner zirconia part showed the martensitic transformation of t-type zirconia to stripe-like m-type zirconia. After the plasma spraying, the interface between alumina and zirconia changed significantly, which formed a new oxide layer. The phase transition mechanism in the ceramic particle and oxide layer formation mechanism at the alumina/zirconia interface were investigated.     

Egg shell waste as an activation agent for the manufacture of porous carbon

Egg shell waste was used as an activation agent directly for the manufacture of a biomass-derived porous carbon,which possessed a surface area of 626 m~2·g~(-1) and was rich in nitrogen, sulfur and oxygen functionalities. The activation mechanism was proposed, and the carbon showed its potential to act as an adsorbent for the adsorptive removal of various contaminants from both aqueous and non-aqueous solutions, possessing maximum adsorption capacities of 195.9, 185.1, 125.5 and 44.6 mg·g~(-1) for sulfamethoxazole, methyl orange, diclofenac sodium and dibenzothiophene, respectively. Through the utilization of egg shell waste as a sustainable activation agent, this work may help to make the widely applied biomass-derived porous carbons more economical and ecological.     

Effect of the water content of padded cotton fabrics on reactive dye fixation in the pad-steam process

A series of padded cotton fabrics with various water contents were obtained through vacuum dehydration. The effects of the water content on the fabric temperature variation during steaming, the colour properties, and the dye fixation rate (%F) were investigated. Dye distribution in the dyed cotton fibres was assessed. The influences of steaming time and sodium carbonate concentration on K/S value and %F of the dyed fabrics with low water content were also evaluated. The results indicate that reducing the water content of the padded cotton fabric to around 25.0% prior to steaming was favoured for reactive dyeing. The temperature of the wet fabric rose rapidly, the K/S value and %F were enhanced, and in addition the dye penetration into the dyed cotton fibres was sufficient. However, for padded fabrics with extraordinarily low and high water contents (e.g. 1.4% and 70.9% respectively), both the K/S value and %F were decreased. Furthermore, a white core phenomenon was evident for the fibres of the dyed fabric with a water content of 1.4%. Variation in the L^* values was in line with the K/S values as the fabric water content varied. As expected, steaming time and sodium carbonate dosage can also affect reactive dye fixation greatly and should be determined accordingly for dyeing cotton fabric with low water content.     

Triblock copolymer-assisted synthesis of hierarchical ZIF-67 in the presence of 1,3,5-trimenthylbenzene

A hierarchically porous ZIF-67 was successfully synthesized by using non-ionic block copolymers P123 as a supramolecular templating surfactant and 1,3,5-trimethylbenzene (TMB) as a swelling agent. It was noted that TMB was an effective swelling agent to expand the pore size. Pore size distribution analyses reveal that the as-synthesized hierarchical ZIF-67 has a typical trimodal pore size distribution showing simultaneous micro-, meso- and macropore channel systems. Due to the effect of TMB and P123, the diameter of ZIF-67 nanoparticles was about twice of that synthesized with P123 only and larger pores were formed among the enlarged nanoparticles. This strategy is expected to be a facile and efficient method for the preparation of hierarchical ZIF-67.     

Microstructure evolution and mechanical properties of ultrasonic assisted laser clad yttria stabilized zirconia coating

Yttria stabilized zirconia (YSZ) coatings were fabricated on a titanium alloy substrate by ultrasonic assisted laser cladding technique and the effect of ultrasonic vibration on the microstructureevolution and mechanical properties was investigated. Experimental results indicated that with the increase of ultrasonic output power, the clad depth increased, the wettability between coating and substrate was improved, the size of equiaxed grains in the cladding zone decreased, and the band structures were broken up gradually. Simultaneously, the element content distribution along the thickness of coating in the transition region changed from exponential to linear distribution gradually, together with the increase of dilution rate. With the increase of ultrasonic output power, the microhardness distribution of fusion zone also converted from an exponential to a linear distribution. Additionally, the friction and wear tests showed that the wear mechanism of coatings both with and without ultrasonic vibration was abrasive wear while the friction coefficients of coating with ultrasonic vibration were lower than that without ultrasonic vibration, which was related to the refined microstructures within the YSZ coatings.     

On the compatibility of dual phase BaCe0.65Zr0.2Y0.15O3-based membrane for hydrogen separation application

Among dense ceramic membranes for H₂ separation, the ceramic-ceramic composite ones have recently gained the interest of the scientific community thanks to their enhanced performances. However, the ceramic phases constituting the composite must show high chemical and thermomechanical compatibility to form a crack-free and robust membrane. This work reports the compatibility between the BaCe_0.65Zr_0.2Y_0.15O_3−δ (BCZY) proton conductive system and various electron conducting systems belonging to four different families: ceria-based (CeO₂ and Ce_0.8Gd_0.2O_1.9), lanthanum nickelate cobaltite (La_0.95Ni_0.6Co_0.4O_3−δ), strontium titanate (Sr_0.9La_0.1TiO_3−δ) and the non-oxidic α-SiC. This work highlights how the coupling of BCZY with chemically different electron-conductive ceramics represents a challenging task, since La_0.95Ni_0.6Co_0.4O₃, Sr_0.9La_0.1TiO₃ and α-SiC react with the proton conductive perovskite producing many secondary phases in air and in reducing atmosphere after 4 h of permanence at 1400 °C. As may be expected, BCZY is chemically compatible with CeO₂ and Ce_0.8Gd_0.2O_1.9 in air and in reducing atmosphere after 4 h of permanence at 1400 °C. Dilatometric results prove the thermomechanical compatibility between BCZY and the ceria-based systems in the operation temperature range.     

A novel method for fabricating of high-performance multi-seeding GdBCO bulk superconductors

A novel multi-seeding (NMS) method is proposed for improving the performances of GdBCO samples by optimizing the shapes and the space configurations of the single-domain GdBCO grains. Three multi-seeding GdBCO bulk superconductors with dimensions of 60 × 20 × 14 mm³ were fabricated by a Gd + 011 infiltration growth method with different seeding techniques: samples S1 and S2 by the traditional multi-seeding method (TMS) with two and three seeds, respectively; and sample S3 by the NMS method with three seeds. The results show that among the three, sample S3 has both of the largest levitation force, 111 N, and the largest magnetic field coupling ratio, 68.57%, which are clearly higher than the levitation force of 100 N and 90 N, and the magnetic field coupling ratios of 34.25% and 11.33% for the samples S1 and S2, respectively. These results indicate that the NSM method is a useful way to improve the mechanical strength, homogeneity, and performances of multi-seeding GdBCO samples.     

Fabrication and microstructure of porous SiC ceramics with Al2O3 and CeO2 as sintering additives

In the present study, porous silicon carbide ceramics were prepared via spark plasma sintering at relatively low temperatures using Al₂O₃ and CeO₂ as sintering additives. Sacrificial template was selected as the pore forming mechanism, and gelcasting was used to fix the slurry in a short time. The evolution process of the microstructures during different steps was observed by SEM. The influence of the sintering temperature and sintering additives on the shrinkage and porosity of the samples was studied. The microstructures of different samples were characterized, and the mechanical properties were also evaluated.     

Low leakage current of CdSe quantum dots/Si composite structure and its performance for photodiode and solar cell

The CdSe quantum dots were deposited on p type Si(100) substrate by spin coating process. CdSe quantum dots were selected as the interlayer to reduce the reverse-bias leakage current of heterojunction. Various junction parameters were determined from the current-voltage (I–V) and capacitance-voltage (C–V) characteristics. Au/CdSe quantum dots/p-Si structure exhibits a fairly low leakage current density of 4.54×10⁻⁹ A/cm² and a high rectification ratio of 3.1×10⁶ at applied electric field of ±4 V. Furthermore, I-V characteristics under illumination show strong photovoltaic (PV) behavior. These results are attributed to the low interfacial state density and defect density due to CdSe quantum dots at the interface. It is also evaluated that the Au/CdSe quantum dots/p-Si structure can be a potential candidate for photodiode and solar cell applications.