THE MAIN OBJECTIVE OF THIS STUDY WAS TO DEVELOP CELLULOSE NANOFIBERS FROM THE THERMOME- CHANICAL PULP (TMP) OF RADIATA PINE (PINUS RADIATA D. DON), AND FOR THIS, A ONE-STEP MICRO-GRINDING PROCESS WAS USED. THE NEWLY DEVELOPED MATERIAL WAS CALLED THERMOMECHANICAL PULP NANOFIBERS (TMP-NF). IN THE FIRST INSTANCE, A DETERMINATION OF THE CONSTITUENTS OF THE TMP WAS CARRIED OUT THROUGH A CHEMICAL CHARACTERIZATION. THEN, TMP-NFS WERE COMPARED WITH CELLULOSE NANOFIBERS (CNF) BY MORPHOLOGICAL ANALYSIS (SCANNING ELECTRON MICROSCOPY, SEM, AND ATOMIC FORCE MICROSCOPY, AFM), X-RAY DIFFRACTION (XRD) AND FOURIER-TRANSFORM INFRARED SPECTROSCOPY WITH ATTENUATED TOTAL REFLECTION (FTIR-ATR). IN ADDITION, FILMS WERE DEVELOPED FROM TMP-NF AND CNF USING A VACUUM FILTRATION MANUFACTURING METHOD. FOR THIS STUDY, 0.10, 0.25, 0.50, AND 1.00% DRY WEIGHT OF CNF AND TMP- NF WERE USED AS CONTINUOUS MATRICES WITHOUT ORGANIC SOLVENTS........

THE ACCUMULATION OF PLASTIC WASTE AND INFECTIOUS DISEASES HAS LED THE SCIENTIFIC COMMUNITY TO SEARCH FOR NEW MATERIALS TO MAKE NANOCOMPOSITES BIOFILMS. WITH THE HELP OF NANOTECHNOLOGY, THE MATERIALS THAT MAKE UP THE NEW NANOCOMPOSITES BIOFILM CAN BE MANIPULATED, ACHIEVING AN IMPROVEMENT IN ITS MECHANICAL PROPERTIES AND GRANTING ANTIMICROBIAL POWERS. BIOFILMS BASED ON ELECTROSPUN FIBERS AS A BARRIER MATERIAL CAN PROTECT AGAINST INFECTIOUS MICROORGANISMS. FOR THESE APPLICATIONS, THE ELECTROSPINNING METHOD ALLOWS THE ENCAPSULATION OF ACTIVE AGENTS IN THE POLYMERIC FIBERS. THIS ARTICLE PRESENTS THE DEVELOPMENT OF A NANOCOMPOSITES BIOFILM WITH POTENTIAL USE AS AN ANTIMICROBIAL BARRIER, WHICH INCORPORATES POLYLACTIC ACID MICROFIBERS WITH ACTIVE AGENTS. AMONG THEM, COPPER IONS SUPPORTED ON CHILEAN NATURAL ZEOLITE NANOPARTICLES AND REINFORCED WITH ACETYLATED CELLULOSE NANOFIBERS. THE STUDY BEGINS WITH OBTAINING CELLULOSE NANOFIBERS THROUGH MECHANICAL METHODS. NANOFIBERS WERE ACETYLATED TO ENSURE ADEQUATE DISPERSION IN THE POLYMER MATRIX AND TO IMPROVE THE MECHANICAL PROPERTIES OF BIOFILMS. POLYMERS AND NANOPARTICLES WERE INCORPORATED INTO BIOFILMS THROUGH A DUAL CONFIGURATION (SIMULTANEOUS INJECTION) ELECTROSPINNING STAGE.

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.

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.

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.

QUASISTATIC NANOINDENTATION IS A PROVEN TOOL THAT PROVIDES INFORMATION ON THE MICROMECHANICAL BEHAVIOR OF WOOD CELL WALLS. HOWEVER, QUASISTATIC TESTS CANNOT PROBE THE TIME-DEPENDENT MECHANICAL BEHAVIOR SHOWN BY WOOD. NANOINDENTATION DYNAMIC MECHANICAL ANALYSIS (NANODMA) CAN MEASURE THE VISCOELASTIC PROPERTIES OF WOOD CELL WALLS. THIS RESEARCH AIMED TO STUDY THE QUASISTATIC AND VISCOELASTIC PROPERTIES OF INDIVIDUAL RADIATA PINE WOOD (PINUS RADIATA D. DON) CELL WALL LAYERS. TO MINIMIZE VARIABILITY AND RETRIEVE BOTH PROPERTIES AT THE SAME LOCATIONS, A LOAD FUNCTION COMPOSED OF A MULTILOAD-QUASISTATIC FUNCTION FOLLOWED BY DYNAMIC REFERENCE FREQUENCY SEGMENTS WAS DEVELOPED. NANOINDENTATIONS WERE THEN PERFORMED ON THE S2 LAYER AND COMPOUND CORNER MIDDLE LAMELLA (CCML) OF UNEMBEDDED LATEWOOD CELLS. BECAUSE THE S2 LAYER IS ANISOTROPIC, BOTH TRANSVERSE AND LONGITUDINAL?TANGENTIAL WOOD PLANES WERE STUDIED. IN THE TRANSVERSE PLANE, THE AVERAGE RESULTS OF THE QUASISTATIC ELASTIC MODULI (??) FOR THE S2 LAYER AND CCML WERE 15.7 GPA AND 4.6 GPA, RESPECTIVELY. IN THE LONGITUDINAL?TANGENTIAL PLANE, THE ?? WAS 3.9 GPA. IN THE TRANSVERSE SECTION, THE HARDNESS (?) OF THE S2 LAYER AND CCML WERE 331 MPA AND 277 MPA, RESPECTIVELY, AND IN THE LONGITUDINAL?TANGENTIAL SECTION H WAS 244 MPA. TO ACQUIRE THE VISCOELASTIC PROPERTIES, MEASUREMENTS WERE MADE OVER MORE THAN THREE DECADES OF FREQUENCY. AN INCREASE OF THE STORAGE MODULUS (??), AND A REDUCTION OF THE LOSS MODULUS (??) AND LOSS FACTOR (TAN?) AS FREQUENCY INCREASED WERE FOUND IN BOTH WOOD ORIENTATIONS. THE QUASI-STATIC AND DYNAMIC INDENTATIONS EQUIVALENT AT 0.1 HZ SHOWED SIMILAR VALUES FOR ?? AND E?. THIS STUDY CONTRIBUTES TO OUR KNOWLEDGE OF WOOD CELL WALL MICROMECHANICAL PROPERTIES.