In this study, a novel hybrid material based on Polyvinyl Alcohol-Chitosan (PVA-Chi) was made, reinforced with conductive fillers such as the polypyrrole (PPy), Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS), carbon black (CB), and multi-wall carbon nanotube (MWCNT). In order to observe the mechanical and electrical responses of this composite material, for obtaining composite materials, and to characterize them for the development of applications in engineering, FTIR analysis made clear the different functional groups present in the matrix and the fillers used. Using quaternary mixtures (4 fillers) increased the contact angle, which increased hydrophobicity of the biocomposite. The Nyquist diagram of the analyzed samples showed a decrease in resistance and energy diffusion; the latter because of transferring electrons caused by the conductive polymers CB and the MWCNT. In the mechanical tension tests, Young’s modulus values of 18.386 MPa were obtained, in contrast with the material matrix of PVA-Chi, which showed values of 11.628 MPa. Morphological analysis by SEM showed the materials got were homogeneous. The materials got showed higher electrical conductivity in the OH’s presence and NH₂ groups, which could have possible applications in biopolymer electrodes.

Agroindustrial residues represent a serious environmental problem in the world; in this case, the polluting rice husk, present in the rice fields of Morelos State, is one source of incalculable biomass. The aim of this study was to assess two viable and optimized procedures for obtaining nanocellulose from these wastes. The sieved samples included 4 treatments with different grain sizes (sieves # 10, 15, 30, and 50) and three replicates. They were then processed by an alkaline treatment (NaOH) 5, bleaching with sodium hypochlorite, followed by pretreatment with 0.65 hydrochloric acid (HCl). After drying, the cellulose was subjected to acid hydrolysis with (H₂SO₄) at 64, and was compared to an enzymatic hydrolysis complex. This complex was formed of D-(+) cellobiose and endo-1,4-β-D-glucanase from Acidothermus cellulolyticus. End products were sonicated and dialyzed until they reach a neutral pH. Finally, the nanocellulose was characterized by FTIR, DSC, XRD, SEM, and TEM. Evident results recognize the nanocellulose (NC) synthesis by both routes, with greater contaminants generated in the medium by the acid hydrolysis. It is much more feasible and faster to achieve with enzymatic hydrolysis, less aggressive for the environment, and higher performance. In future trials, the cost-benefit of using the enzyme complex should be assessed as an alternative to replace acid hydrolysis.Key words: acid hydrolysis, enzymatic hydrolysis, waste, rice husk, Oryzasativa L, cellulose nanocrystals (CNCs).

This paper presents a tunable, switchable multi-wavelength emission from an erbium-doped fiber ring laser, enabled by adjusting the spectral fringe visibility of a fiber interferometer filter. The filter is formed with specially designed concatenated tapered fibers to configure a Mach-Zehnder fiber interferometer (MZFI). The laser emission is highly flexible and reconfigurable, allowing for tuning between single- and dual-wavelength operation. The laser can switch sequentially from one up to six wavelengths by fixing the curvature and adjusting the polarization state. The lasing emission is generated over a stable wavelength range between 1559.59 nm and 1563.54 nm, exhibiting an optical signal-to-noise ratio (OSNR) exceeding ~35 dB. The performance of amplitude and wavelength fluctuations were evaluated, indicating an appropriate stability of ~3 dB and a shift less than 0.1 nm within a 45 min period at room temperature. A detailed comparison with the literature is given.

This work reports the obtention of nanocompounds from epoxy resin (EP) with graphenes at three different oxidation degrees (GO1, GO2, and GO3), functionalized with 3-glycidyloxypropyl trimethoxysilane (GPTMS), and three different graphene concentrations (1%, 2%, and 3%). The aim is to improve GO compatibility in EP and obtain a nanocompound with synergistic properties. Ultrasonic bath was used to disperse the GO, a factor in the effective interaction between GO and the polymeric matrix. The nanocompounds were characterized by FTIR, SEM, and mechanical tension testing. The FTIR analysis evidenced stretching bonds created during the functionalization of graphene oxide (GO) with the silane (GPTMS); they are characteristic Si-O-Si and Si-O-C at 1000 and 1085 cm⁻¹, respectively. There was a difference between GO and GO-GPTMS nanocompounds regarding the formation of these signals. The SEM micrographs showed morphological changes when GO was added: the smooth fracture surface of EP became rougher. During tension testing, Young’s modulus (2.09 GPa) of GO2-GPTMS/epoxy nanocompounds (1% weight GO) increased by 35% while their resistance to traction (98.71 MPa) grew by 52%; both were higher than in pure EP. In conclusion, the variables studied (oxidation degrees and silanization) significantly affect the mechanical properties studied.

El principal problema que enfrentan los residuos agroindustriales es la falta de conciencia ambiental de los productores, sumado a los pocos recursos destinados al desarrollo de nuevas tecnologías y las pobres políticas gubernamentales para el manejo de dichos residuos. Lo anterior genera fuentes puntuales de contaminantes atmosféricos y nos hace cómplices del cambio climático por la emisión de gases efecto invernadero y contaminantes climáticos de vida corta, como el carbono negro. En las últimas décadas, se ha puesto gran interés por el descubrimiento del nuevo mundo de las nanopartículas y en particular el de la nanocelulosa. Algunos logros, ya son visibles y tienen múltiples aplicaciones. Pero si bien es cierto que hay numerosos avances en la obtención de estas nanomaterias a partir de distintos tipos de fibras naturales o residuos postcosecha, aún falta investigación para lograr la factibilidad de tales tecnologías, principalmente por los gastos energéticos y los costos de producción. En esta revisión se ofrece un resumen de diversos ensayos de laboratorio que reconocen la posibilidad de obtención de nanocelulosa a partir de residuos postcosecha, mediante diversos métodos, con el fin de despertar el interés por perfeccionar la logística de las técnicas y la eficiencia de los procesos que se ofrecen a partir de diferentes residuos agroindustriales.

In this work, aerogels were obtained by vacuum drying, an uncommon method that requires lower energy costs and creates materials with high porosity and small pore size. Starch from A98 rice was used, evaluating different concentrations (8, 10, and 12%) and retrogradation times (2, 4, and 6 days). The aerogels were characterized by analysis in a scanning electron microscope, in a Fourier transform infrared spectrophotometer and differential scanning calorimetry. Importantly, the retrogradation time showed no apparent significant changes in the formulation of the materials, and those created at a concentration of 10% presented a crystalline and amorphous reorganization. They were more homogeneous than the rest of the formulations while their pores measured 41 nm. Aerogels formulated with 8% presented higher swelling and water absorption but reduced solubility. The aerogels reported in this work show promising characteristics and the drying technique opens the doors to a more practical method that deserves further research.