Tying together the ultrastructural modifications of wood fibre induced by pulping processes with the mechanical properties of paper

The composition and ultrastructural arrangement of cell wall polymers in wood fibres have determining influence on the properties of wood derived materials. It is therefore important to improve our understanding of the relationship between fibres organisation, the modifications induced by pulping treatments, and the resulting paper sheet mechanical properties. The different treatments to which fibres are subjected during the manufacturing of pulps and papers induce morphological and micro-structural alterations due to the removal of wall constituents and of microfibrillar elements. The impact of pulping processes on fibres was investigated at the ultrastructural scale of transmission electron microscopy. Particular attention was given to the effects of beating in refiners at various intensities on the ultrastructure of fibres. The most characteristic effects consisted of delaminations, microfibril disorganisation, and even fractures, of varying importance depending on the intensity of the mechanical refining. The consequences of internal alterations and surface modifications of the fibres were examined in relation to the paper sheet mechanical properties. Correlations between the type of alteration observed in the fibres and its possible impact on a given paper mechanical property are suggested. With similar approaches, the effects of drying and recycling were studied.     

两性淀粉接枝共聚物在中性抄纸中的应用

为考察两性淀粉与丙烯酰胺接枝共聚及阳离子合成的具有功能化、网络化的多元变性淀粉对纸张的增强效果,采用废纸浆为原料,在中性抄纸条件下,对该多元变性淀粉的增强应用性能进行了研究。结果发现,两性淀粉与丙烯酰胺接枝共聚物(AS-g-PAM)及其阳离子化的衍生物(AS-g-CPAM)比两性淀粉具有更好的增强效果,尤其可大幅度提高纸张的环压强度。与两性淀粉比较,用量为0.5%AS-g-PAM和AS-g-CPAM可分别提高环压指数22%和45%以上,对纸张的抗张指数、耐破度等也比使用两性淀粉有不同程度的提高,同时,AS-g-CPAM在0.05%的低用量时,仍具有较好的增强效果。     

Deposition of ZnS thin film by ultrasonic spray pyrolysis: effect of thickness on the crystallographic and electrical properties

Zinc sulfide (ZnS) thin films have been deposited on Si (1 0 0) substrate using ultrasonic spray pyrolysis. X-ray diffraction (XRD) analysis revealed that the films are (0 0 2) preferentially oriented with c-axis-oriented wurtzite structure. The crystallinity has been found to improve with film thickness in the 180–6000 nm range. Film structure has been analyzed by XRD, scanning electron microscope, FTIR, and Raman spectroscopies, while the stoichiometry has been verified by energy-dispersive spectroscopy and particle-induced X-ray emission techniques. Electrical properties of the grown films were characterized by current–voltage and capacitance–voltage measurements where, the films show better conducting behavior at higher thickness.     

HEAT TRANSFER AND PRESSURE DROP FROM LOUVERED SURFACES IN AUTOMOTIVE HEAT EXCHANGERS

An investigation of heat transfer and pressure drop from some louvered surfaces is presented. The test rig and the measuring as well as the data evaluating procedures are described. The measured data are transferred and presented in a nondimenswnal form. The heal transfer data are provided mainly as Stanton numbers versus Reynolds number, and the pressure drop is given as Darcy friction factors versus Reynolds number. For comparing the performance of the various louvered surfaces, the flow area goodness factors and the so-called volume goodness factors are presented. All the louvered surfaces have been found to be more efficient than the corresponding smooth surface. The standard multilouvered fin surfaces were found to be most efficient, but one of the new surfaces also performed very well.     

Sustainable and Robust Graphene Cellulose Paper Decorated with Lithiophilic Au Nanoparticles to Enable Dendrite-free and High-Power Lithium Metal Anode

Lithium metal anodes (LMAs) with high energy density have recently captured increasing attention for development of next-generation batteries. However, practical viability of LMAs is hindered by the uncontrolled Li dendrite growth and infinite dimension change. Even though constructing 3D conductive skeleton has been regarded as a reliable strategy to prepare stable and low volume stress LMAs, engineering the renewable and lithiophilic conductive scaffold is still a challenge. Herein, a robust conductive scaffold derived from renewable cellulose paper, which is coated with reduced graphene oxide and decorated with lithiophilic Au nanoparticles, is engineered for LMAs. The graphene cellulose fibres with high surface area can reduce the local current density, while the well-dispersed Au nanoparticles can serve as lithiophilic nanoseeds to lower the nucleation overpotential of Li plating. The coupled relationship can guarantee uniform Li nucleation and unique spherical Li growth into 3D carbon matrix. Moreover, the natural cellulose paper possesses outstanding mechanical strength to tolerate the volume stress. In virtue of the modulated deposition behaviour and near-zero volume change, the hybrid LMAs can achieve reversible Li plating/stripping even at an ultrahigh current density of 10 mA cm⁻² as evidenced by high Coulombic efficiency (97.2 % after 60 cycles) and ultralong lifespan (1000 cycles) together with ultralow overpotential (25 mV). Therefore, this strategy sheds light on a scalable approach to multiscale design versatile Li host, promising highly stable Li metal batteries to be feasible and practical.     

Investigation of molar concentration effect on structural,optical, electrical,and photovoltaic properties of spray‐coated Cu2O thin films

High quality copper oxide thin films were prepared by nebulizer spray pyrolysis technique using different concentrations of copper precursor solution. Concentration‐dependent structural, morphological, optical, and electrical properties of the prepared films are discussed. X‐ray diffraction studies done for the samples confirmed that the deposited films are in Cu₂O phase with polycrystalline cubic structure. Atomic force microscopy analysis revealed that all the films are composed of nano sheet shaped grains covering the substrate surface. Optical studies done on the samples showed band gap values 2.42, 2.31, and 2.02 eV for the solution concentration 0.01, 0.05, and 0.1 M, respectively. Photoluminescence spectral analysis showed the emission band at 620 nm confirming the formation of cuprous oxide. Electrical analysis of the films showed p‐type conductivity with a low resistivity 2.19 × 10² Ω.cm and high carrier concentration 16.76 × 10 ¹⁵ cm⁻³ for the molar concentration 0.1 M. In this work, Cu₂O/ZnO heterojunctions were also prepared, and solar cell properties were studied; they were found to show increased open circuit voltage and short circuit current for higher copper concentration.     

彩虹自标定方法对混合喷雾比例的原位测量

传统彩虹测量技术标定复杂、精度可重复性差且难以适应密闭空间。一种基于多彩虹谱线自标定方法,可省去原有的标定系统装置,将标定过程内化于对彩虹信号的处理,以水为例的测量偏差仅为0.13%。将该技术应用于混合喷雾液滴组分浓度测量中,探究并优化了参与混合的两种液体组分的方案。实验采用60%乙醇-水混合喷雾,原位测量了混合喷雾场多点组分浓度,测量结果差别可以控制在0.5%以内,表明该方法技术在相关领域的应用潜力。