Effect of Incorporation of Graphene Nanoplatelets on Physicochemical, Thermal, Rheological, and Mechanical Properties of Biobased and Biodegradable Blends.

This work aimed to study the effect of the incorporation of graphene nanoplatelets (GRA 0.5% and 1% (w/w)) on the matrices of biobased polymers composed of starch-based materials (B20) and poly(butylene succinate) (PBS) using pine rosin (RES) as a compatibilizer. Three formulations were produced (B20/RES/PBS, B20/RES/PBS/GRA0.5%, and B20/RES/PBS/GRA1%), and their mechanical properties (tensile, flexural, hardness, and impact), rheological behavior, thermal properties (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)), chemical analysis (Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy), and contact angle were evaluated. Hardness (Shore D), tensile, and flexural moduli increased, whereas elongation at break and toughness decreased as GRA content increased. FTIR studies strongly supported the existence of interactions between polymeric matrices and the large surface area of GRA. The viscosity flow curves were well fitted to the Cross-Williams-Landel-Ferry (Cross-WLF) model, and the three formulations exhibited non-Newtonian (shear-thinning) behavior. The analysis of water contact angles indicated that the formulation surfaces have hydrophilic behavior. All the samples are thermally stable, and the results of this study can be used to optimize the application of biobased graphene-based composites for applications in injection molding industries.

Reproducibility Study of the Thermoplastic Resin Transfer Molding Process for Glass Fiber Reinforced Polyamide 6 Composites.

Polyamide 6 (PA6) thermoplastic composites have higher recyclability potential when compared to conventional thermoset composites. A disruptive liquid molding manufacturing technology named Thermoplastic Resin Transfer Molding (T-RTM) can be used for processing composites due to the low viscosity of the monomers and additives. In this process, polymerization, crystallization and shrinkage occur almost at the same time. If these phenomena are not controlled, they can compromise the reproducibility and homogeneity of the parts. This work studied the influence of packing pressure, as a process variable, throughout the filling and polymerization stages. To assess the process reproducibility and parts' homogeneity, physical, thermal and mechanical properties were analyzed in different areas of neat PA6 and composite parts. This study showed that a two-stage packing pressure can be successfully used to increase parts' homogeneity and process reproducibility. The use of 3.5 bar packing pressure during the polymerization stage resulted in mechanical properties with lower standard deviations, indicating a higher degree of homogeneity of the manufactured parts and higher process reproducibility. These results will be used for establishing the actual state of the technology and will be a base for future process optimization.

Moisture Sorption Isotherms and Thermodynamic Properties of Biodegradable Polymers for Application in Food Packaging Industry.

This work aims to evaluate the influence of two starch-based materials (B16 and B20) on the moisture sorption isotherms, determined at 30, 40, and 50 °C, where B16 contains 5% (w/w) more starch than B20. Thermodynamic functions (differential enthalpy (∆Hdif), differential entropy (∆Sdif), integral enthalpy (Δhint), integral entropy (ΔSint), free Gibbs energy (∆G), and spreading pressure (φ)) were used to understand the water-binding behaviors and the energy requirements to remove the moisture content from the surface of these materials. The moisture sorption isotherms exhibited type III behavior, and the Guggenheim-Anderson-de Boer (GAB) model was the most suitable to fit the experimental moisture adsorption data. The adsorption isotherms of microparticles were enthalpy-controlled, with isokinetic temperature values of 221.45 and 279.77 K for B16 and B20, respectively, being higher than the harmonic mean temperature (312.94 K). The values of ∆G were positive (45.274 and 44.307 kJmol-1 for B16 and B20, respectively), indicating a non-spontaneous process. The spreading pressure values increased with increasing water activity (aw) for all isotherms. Higher values of ∆Hdif and ∆Sdif obtained from B16 confirmed its higher number of sorption sites available for binding with water molecules when compared to B20, making it less suitable for application in the food packaging industry.

Muscle Daily Undulating Periodization for Strength and Body Composition: The Proposal of a New Model.

The traditional linear periodization model is designed for modifications to be performed over several weeks, whereas alterations in the undulating model are applied on a more frequent basis. The study investigated a novel periodization scheme, the muscle daily undulating periodization model (mDUP). Thirty-seven men were randomly assigned into 2 groups: (a) a group that performed 12 weeks of daily undulating periodization with fix overload (DUP-F) resistance training (n = 19) and (b) a group that performed 12-weeks of muscle daily undulating periodization with variation overload (mDUP) (n = 18). Body composition and strength assessments (muscular endurance and one repetition maximum [1 RM] for barbell bench press, 45º leg press, lat pull down, and standing arm curl) were completed before and after the program. Two-way MANOVA with repeated measures was used to compare groups with significance set at p<0.05. There were no differences between periodization programs for anthropometric variables (p > 0.05, η2p = 0.04), but improvement was noted over time (p < 0.001, η2p = 0.60). No differences were observed between periodization programs for strength (p > 0.05, η2p = 0.056), but strength increased over time (p < 0.001, η2p = 0.95). Similarly, no muscular endurance differences were seen between periodization programs (p > 0.05, η2p = 0.15), but measures increased over time (p < 0.001, η2p = 0.60). When it comes to body composition, muscle strength, and muscle endurance, the present study provides evidence that both periodization models displayed similar results, with more evident improvements in strength. Thus, it seems pertinent to consider this new periodization model plausible for RT practitioners in order to achieve new adaptations.

Effects of Combined Resistance Plus Aerobic Training on Body Composition, Muscle Strength, Aerobic Capacity, and Renal Function in Kidney Transplantation Subjects.

ABSTRACT: Lima, PS, de Campos, AS, de Faria Neto, O, Ferreira, TCA, Amorim, CEN, Stone, WJ, Prestes, J, Garcia, AMC, and Urtado, CB. Effects of combined resistance plus aerobic training on body composition, muscle strength, aerobic capacity, and renal function in kidney transplantation subjects. J Strength Cond Res 35(11): 3243-3250, 2021-Immunosuppression and a sedentary lifestyle may exacerbate complications such as early graft dysfunction and muscle loss, and reduce patient survival after kidney transplantation (KT). Therefore, the purpose of this study was to evaluate changes in body composition (BC), muscular strength, aerobic, and renal function in KT subjects submitted to combined resistance plus aerobic training. Twelve KT subjects were randomly assigned into groups: (G1) 12 weeks of combined training (3 males and 4 females, 54 ± 3 years); or (G2) nonexercise control (5 females, 43 ± 18 years). The subjects were evaluated for BC (dual-energy X-ray absorptiometry), estimated V̇o2peak, right-hand maximal grip strength (RHMGS) and left-hand maximal grip strength (LHMGS), and renal function. Post-training revealed that G1 reduced body fat percentage (p = 0.046), uric acid (Δ = -0.87; p = 0.023), urea (Δ = -9.43; p = 0.032), and creatinine (Δ = -0.15; p = 0.045), increased fat-free mass, estimated V̇o2peak, RHMGS, LHMGS (p < 0.05), and estimated glomerular filtration rate (eGFR) (Δ = 11.64; p = 0.017). G2 increased urea (Δ = 8.20; p = 0.017), creatinine (Δ = 0.37; p = 0.028), and decreased eGFR (Δ = -16.10; p = 0.038). After 12 weeks, urea (Δ = 24.94; p = 0.013), uric acid (Δ = 1.64; p = 0.044), and creatinine (Δ = 0.9; p = 0.011) were lower, whereas eGFR (Δ = 36.51; p = 0.009) was higher in G1. These data indicate that combined training instigates positive changes in BC, muscular strength, aerobic capacity, and renal function after KT.

Consumption Rates and Performance of Erinnyis ello L. on Four Cassava Varieties / Taxas de Consumo e Desempenho de Erinnyis ello L. em Quatro Variedades de Mandioca

O consumo foliar de mandioca (Manihot esculenta Crantz) e a caracterização da injúria potencial por Erinnyis ello L. foram determinados em quatro variedades de mandioca. Lagartas deprimeiro ínstar foram criadas individualmente em folhas de quatro variedades de mandioca. Foi usado o delineamento experimental de blocos ao acaso com nove repetições. Folhas frescas com áreas previamente determinadas foram fornecidas às larvas diariamente. O consumo foliar em cada ínstar e o peso das lagartas e pupas foram registrados. Não houve diferença significativa no consumo foliar nas quatro variedades (P=0,82). O total de área foliar consumida (cm2) para as variedades testadas foi: 1030,5 (Fio de Ouro), 971,5 (Aipim Bravo), 968,6 (Urubu), 956,1 (Jaburu), sendo de 981,7 o consumo médio das quatro variedades. Aproximadamente 94% do consumo ocorreu durante os dois últimosínstares. Variedades não afetaram o desenvolvimento larval (P=0,96). Os pesos médios de lagartas (g) em cada variedade foram: 4,9 (Jaburu), 4,8 (Fio de Ouro), 4,7 (Urubu), 4,6 (Aipim Bravo) e 4,8 (média das quatro variedades). Dois modelos, um relacionando a área foliar consumida e desenvolvimento larval ( y = abxcx2) e outro do crescimento larval (y=5/1+ea+bx), foram estabelecidos. Os dados obtidos indicam que as variedades testadas neste estudo foram nutricionalmente semelhantes para odesenvolvimento de E. ello. Como o consumo foliar de E. ello foi semelhante para todas as variedades, a mesma taxa de consumo pode ser usada para o cálculo dos níveis de dano econômico para manejar E. ello nessas variedades.

A laboratory experiment to determine the consumption rates of cassava (Manihot esculenta Crantz) and characterize the injury potential by Erinnyis ello L. was conducted. First instar larvae were individually reared on excised cassava leaves of four varieties. A randomized block designwith nine replications was used. Fresh leaves were provided to the larvae daily. Leaf area was determined for each leaf before the leaves were provided to the larvae. Foliage consumption per instar, developmentaltime and weight of larvae and pupae were recorded. There were no significant differences in the larvalconsumption on the four varieties (P=0.82). Total leaf area consumption (square cm) for the varieties were: 1030.5 (Fio de Ouro), 971.5 (Aipim Bravo), 968.6 (Urubu), 956.1 (Jaburu) and across varieties was 981.6. About 94% of the feeding occurred during the last two larval instars. Varieties also had no effect on larval development (P=0.96). Mean larval weight (g) were: 4.9 (Jaburu), 4.8 (Fio de Ouro), 4.7 (Urubu), 4.6 (Aipim Bravo), and across varieties was 4.8. Two models, one relating larval leaffeeding and larval development ( y = abxcx2) and another for larval growing (y=5/1+ea+bx), were established. These data indicate that the varieties tested in this study were equally suitable for E. ello development. In addition, because the consumption rates of E. ello are the same across varieties, a single value can be used in determining economic injury levels to manage E. ello on these varieties.