This work reveals the structural variations of cellulose nanofibers (CNF) prepared from different cellulose sources, including softwood (Picea abies), hardwood (Eucalyptus grandis × E. urophylla), and tunicate (Ciona intestinalis), using different preparation processes and their correlations to the formation and performance of the films prepared from the CNF. Here, the CNF are prepared from wood chemical pulps and tunicate isolated cellulose by an identical homogenization treatment subsequent to either an enzymatic hydrolysis or a 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation. They show a large structural diversity in terms of chemical, morphological, and crystalline structure. Among others, the tunicate CNF consist of purer cellulose and have a degree of polymerization higher than that of wood CNF. Introduction of surface charges via the TEMPO-mediated oxidation is found to have significant impacts on the structure, morphology, optical, mechanical, thermal, and hydrophobic properties of the prepared films. For example, the film density is closely related to the charge density of the used CNF, and the tensile stress of the films is correlated to the crystallinity index of the CNF. In turn, the CNF structure is determined by the cellulose sources and the preparation processes. This study provides useful information and knowledge for understanding the importance of the raw material for the quality of CNF for various types of applications.
a Nanocellulose is a recently developed form of cellulose that has the potential to be used in many different industries, ranging from food to high-performance applications. This material is commercially manufactured through the homogenization of chemical pulps, but the process is energy-consuming and is still an important subject for development. Simple, robust methods are required for the quality control and optimization of industrial nanocellulose production. In this study, a number of different methods, based on different principles of monitoring the manufacture of cellulose nanofibers were evaluated and compared for five different nanocellulose qualities, both for their resolution and robustness/ease. Methods based on microscopy, light scattering, centrifugation, and viscosity were examined and all appeared useful for observing the manufacturing process during its initial stage. However, only methods based on centrifugation, turbidity, and transmittance yielded reliable data for the entire manufacturing process. Of these methods, transmittance measurement may be the best candidate for routine use because the method is simple, rapid, and only requires spectrophotometer equipment.
Nougatgefullte Milchschokoladen wurden bei verschiedenen Temperaturen gelagert. Veranderungen in der Zusammensetzung der Triglyceride im Schokoladeniiberzug und in der Fiillung lielen sich anhand von HPLC-Analyse verfolgen. Die bekannten Diffusionsgesetze konnten genutzt werden, um die Kinetik der Migration von Triolein aus Nougat in die Schokoladenschicht zu erfassen. Diese kinetische Beschreibung erklart einige praktische Erfahrungen und laBt sich zur Qualitatskontrolle von mehrschichtigen oder iiberzogenen Schokoladenprodukten nutzen.Kinetics of Fat Migration within Chocolate Products, Part I: Principles and Analytics. Nougat tilled milk chocolates were stored at different temperatures. Changes of the triglycerides compositions within chocolate coating and nougat filling were measured by means of HPLC analysis. The well-known diffusion equations could be applied to describe kinetics of migration of triolein from nougat into the chocolate layer. These kinetics may explain some practical experience and may be used in quality control of multilayer or coated chocolate products.
Results of calculations using a configuration interaction LCAO-MO method are presented for the X 2Σ+ and A 2Π states of BeH. Apart from the 1s shell of Be, the correlation energy of the remaining three electrons is calculated quantitatively using an extended basis set and complete configuration interaction including all single, double and triple replacements. The calculated spectroscopic constants are in excellent agreement with available experimental data. The present calculations also predict a value of De(BeH, X 3Σ+)=2.115 eV, and dismiss the possibility of a potential maximum in the ground state potential energy curve.
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