Effect of the Longitudinal Tensile Creep on the Stiffness of Radiata Pine (Pinus radiata D. Don).

The influence of load on the cellulose microfibrils of single cells or thin wood foils is known. It can decrease the cellulose microfibril angles and, in turn, increase the stiffness. However, this modification of a piece of wood, which is made up of multiple cells, is unknown. The aim of this research was to study the effect of tensile creep on the longitudinal stiffness of radiata pine wood. The modulus of elasticity of each specimen was determined before and after being subjected to tensile creep. The samples were loaded at 1170 N and 1530 N for 20 min at 70 °C. The load was determined as a function of a percentage of the force at the proportional limit. The moduli of elasticity before and post-tensile creep showed no effect on the stiffness of wood at the macroscopic level, but neither were there damage to the cell structure. It can be assumed that there are changes at the microscopic level, but they are not enough to be reflected at the macro scale. It is also challenging to achieve the modifications that occur at the level of a single cell or in thin wood foils; however, the implications of this would be favorable for the development of stronger wood-based products.

Evaluation of the PLA-nZH-Cu Nanocomposite Film on the Micro-Biological, Organoleptic and Physicochemical Qualities of Packed Chicken Meat.

This research evaluated the contribution of nanocomposite films based on different concentrations of nZH-Cu (1%, 2%, and 3%) to the microbiological, organoleptic, and physicochemical characteristics of packed chicken breast meat. Analysis of some meat quality traits, such as microbiological, chemical, and physical, were conducted on a laboratory scale. For this, small squares of chicken breast meat, weighing approximately 10 g, were aseptically wrapped with rectangular pieces of 5 × 10 cm PLA-nZH-Cu nanocomposite films, which were stored at 4 °C for 20 days. The microbiological results indicated efficient antibacterial activity (at any nZH-Cu concentration in the nanocomposite films) on the total viable count of groups of psychrophiles, aerobic mesophiles, Enterobacteriaceae, and Salmonella spp. until day 10 of storage (p < 0.05). No significant changes were observed in the organoleptic (color) and physicochemical qualities (texture, weight, pH, and acidity) until day 10 of storage at 4 °C (p < 0.05). The analysis of the experimental tests carried out determined that the PLA-nZH-Cu nanocomposite films played an effective role in the bacterial safety of the packaged chicken. It was concluded that the nZH-Cu nanocomposite films, at all concentrations tested, extended the shelf life of the chicken breast meat for up to 10 days in a refrigerator at 4 °C.

Obtaining Nanoparticles of Chilean Natural Zeolite and its Ion Exchange with Copper Salt (Cu2+) for Antibacterial Applications.

This article describes the production of nanoparticles of Chilean natural zeolite, using three size reduction methods: Ball mill, microgrinding, and microfluidization. Morphological characterization of samples indicated an average diameter of 37.2 ± 15.8 nm of the zeolite particles. The size reduction and chemical treatments did not affect the morphology or integrity of the zeolite. An increase of the zeolite samples' Si/Al ratio was observed after the acid treatment and was confirmed by SEM-EDX analysis. Moreover, the effectiveness of the copper salt ion exchange (Cu2+) to the zeolite nanoparticles was analyzed by SEM-EDX. XRD analysis indicated that clinoptilolite and mordenite are the main phases of Chilean natural zeolite, and the crystalline structure was not affected by the modification processes. The FTIR characterization showed the presence of chemical bonds of copper with the zeolite nanoparticle framework. The ion-exchanged zeolite nanoparticles were evaluated for antibacterial behavior by the disc diffusion method. Additionally, the minimum inhibitory concentration and minimum bactericidal concentration were obtained. Microbiological assays with copper-exchanged nanozeolites showed an antimicrobial activity with a bactericidal effect against Escherichia coli and Staphylococcus aureus, which are the primary pathogens of food and are also resistant to multiple drugs. In this study, a new application for natural nanozeolites is demonstrated, as the incorporated copper ions (Cu2+) in nanozeolites registered a productive antibacterial activity.

Dissolution and Hydrolysis of Bleached Kraft Pulp Using Ionic Liquids.

Forestry industries in Chile are facing an important challenge-diversifying their products using green technologies. In this study, the potential use of Ionic Liquids (ILs) to dissolve and hydrolyze eucalyptus wood (mix of Eucalyptus nitens and Eucalyptus globulus) kraft pulp was studied. The Bleached Hardwood Kraft Pulp (BHKP) from a Chilean pulp mill was used together with five different ILs: 1-butyl-3-methylimidazolium chloride [bmim][Cl], 1-butyl-3-methylimidazolium acetate [bmim][Ac], 1-butyl-3-methylimidazolium hydrogen sulfate [bmim][HSO4], 1-ethyl-3-methylimidazolium chloride [emim][Cl], 1-ethyl-3-methylimidazolium acetate [emim][Ac]. Experimentally, one vacuum reactor was designed to study the dissolution/hydrolysis process for each ILs; particularly, the cellulose dissolution process using [bmim][Cl] was studied proposing one molecular dynamic model. Experimental characterization using Atomic Force Microscopy, conductometric titration, among other techniques suggest that all ILs are capable of cellulose dissolution at different levels; in some cases, the dissolution evolved to partial hydrolysis appearing cellulose nanocrystals (CNC) in the form of spherical aggregates with a diameter of 40-120 nm. Molecular dynamics simulations showed that the [bmim][Cl] anions tend to interact actively with cellulose sites and water molecules in the dissolution process. The results showed the potential of some ILs to dissolve/hydrolyze the cellulose from Chilean Eucalyptus, maintaining reactive forms.

Isolation and Characterization of Cellulose Nanocrystals from Rejected Fibers Originated in the Kraft Pulping Process.

In the final process of the bleached kraft pulp there are some cellulose fibers that are separated from the main fibers stream; these fibers are rejected and considered as a low quality fibers, these fibers are known as rejected fiber (RF). In the present work the potential use of these fibers for Cellulose Nanocrystals (CNCs) synthesis was studied. The physical and chemical properties of synthesized CNCs were characterized through different techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA). Results demonstrate the feasibility of CNCs synthesis with a yield of 28.1% and 36.9%, and crystallinity of 73.5% and 82.7%. Finally, the morphology and synthesis conditions suggest that this industrial reject fiber (RF) could be used as a source for the CNCs production, thus adding value to the kraft process and opening new possibilities for innovation in the pulp industry.