Catalytic Selective Oxidation of ß-O-4 Bond in Phenethoxybenzene as a Lignin Model Using (TBA)5[PMo10V2O40] Nanocatalyst: Optimization of Operational Conditions.

The catalytic oxidation of phenethoxybenzene as a lignin model compound with a ß-O-4 bond was conducted using the Keggin-type polyoxometalate nanocatalyst (TBA)5[PMo10V2O40]. The optimization of the process's operational conditions was carried out using response surface methodology. The statistically significant variables in the process were determined using a fractional factorial design. Based on this selection, a central circumscribed composite experimental design was used to maximize the phenethoxybenzene conversion, varying temperature, reaction time, and catalyst load. The optimal conditions that maximized the phenethoxybenzene conversion were 137 °C, 3.5 h, and 200 mg of catalyst. In addition, under the optimized conditions, the Kraft lignin catalytic depolymerization was carried out to validate the effectiveness of the process. The depolymerization degree was assessed by gel permeation chromatography from which a significant decrease in the molar mass distribution Mw from 7.34 kDa to 1.97 kDa and a reduction in the polydispersity index PDI from 6 to 3 were observed. Furthermore, the successful cleavage of the ß-O-4 bond in the Kraft lignin was verified by gas chromatography-mass spectrometry analysis of the reaction products. These results offer a sustainable alternative to efficiently converting lignin into valuable products.

Alkalization of Kraft Pulps from Pine and Eucalyptus and Its Effect on Enzymatic Saccharification and Viscosity Control of Cellulose.

Bleached kraft pulps from eucalyptus and pine were subjected to cold caustic extraction (CCE) with NaOH (5, 10, 17.5, and 35%) for hemicelluloses removal and to increase cellulose accessibility. The effect of these changes was evaluated in enzymatic saccharification with the multicomponent Cellic CTec3 enzyme cocktail, and in viscosity reduction of pulps with the monocomponent Trichoderma reesei endoglucanase (EG). After CCE with 10% NaOH (CCE10) and 17.5% NaOH (CCE17.5), hemicellulose content lower than 1% was achieved in eucalyptus and pine pulps, respectively. At these concentrations, cellulose I started to be converted into cellulose II. NaOH concentrations higher than 17.5% decreased the intrinsic viscosity (from 730 to 420 mL/g in eucalyptus and from 510 to 410 mL/g in pine). Cellulose crystallinity was reduced from 60% to 44% in eucalyptus and from 71% to 44% in pine, as the NaOH concentration increased. Enzymatic multicomponent saccharification showed higher glucose yields in all CCE-treated eucalyptus samples (up to 93%) while only CCE17.5 and CCE35 pine pulps achieved 90% after 40 h of incubation. Untreated bleached pulps of both species presented saccharification yields lower than 70%. When monocomponent EG was used to treat the same pulps, depending on enzyme charge and incubation time, a wide range of intrinsic viscosity reduction was obtained (up to 74%). Results showed that eucalyptus pulps are more accessible and easier to hydrolyze by enzymes than pine pulps and that the conversion of cellulose I to cellulose II hydrate only has the effect of increasing saccharification of CCE pine samples. Viscosity reduction of CCE pulps and EG treated pulps were obtained in a wide range indicating that pulps presented characteristics suitable for cellulose derivatives production.

Bio-Degradable Polyurethane Foams Produced by Liquefied Polyol from Wheat Straw Biomass.

In the present work, an abundant and unused residue (wheat straw) has been employed to synthesize a polyol as a substituent of castor oil in polyurethane foams. The liquefied product showed excellent properties for the proposed application. Castor oil was substituted with up to 50% wheat straw polyol in the formulation of polyurethane foams, which were prepared using two different isocyanates (methylene diphenyl diisocyanate (MDI) and toluene-2,4-diisocyanate (TDI)). The evaluation of physical, mechanical, and thermal properties of the foams revealed that these materials can successfully be formed with up to 40% wheat straw polyols since all the results were improved. Moreover, at this polyol concentration, the morphology of the foams was presented as a compact and ordered structure. Following this trend, the foams showed excellent biodegradability at 30 days (5.60 and 7.31% for TDI and MDI foams, respectively) and 60 days (8.49 and 9.88% for TDI and MDI foams, respectively) in the soil media tests carried out. Thus, the materials prepared in this work can be proposed for agricultural applications such as use in plant nurseries.

[Antifungal activity of mouthwashes against Candida albicans and Rhodotorula mucilaginosa: An in vitro study]. / Actividad antifúngica de los enjuagues bucales frente a Candida albicans y Rhodotorula mucilaginosa: un estudio in vitro.

BACKGROUND: Candida albicans and Rhodotorula mucilaginosa are yeasts of clinical importance in the oral cavity. In immunocompromised patients they can cause some pathologies that must be controlled with antimicrobials. AIMS: To evaluate and compare the antimicrobial efficacy of commercially available mouthrinses against strains of C. albicans and R. mucilaginosa. METHODS: The six mouthwashes studied in vitro were formulated (alone or in combination) with chlorhexidine (CHX) 0.12%, CHX 0.1%, CHX 0.05%, cetylpyridinium chloride (CPC) 0.075%, CPC 0.05%, and essential oils. Ten C. albicans and R. mucilaginosa isolates each were studied. The agar diffusion method (Mueller Hinton II), with incubation at 32°C was used to evaluate the antifungal activity. RESULTS: The results of this study indicate that mouthwashes with CHX 0.1%, CHX 0.12%, CHX 0.05% + CPC 0.05%, CHX 0.12% + CPC 0.05% and CPC 0.075% have an antifungal effect against C. albicans and R. mucilaginosa. CHX 0.1% led to the broadest inhibition zone for C. albicans and R. mucilaginosa (25.65±2.39mm and 40.05±3.31mm). Essential oils did not show any antifungal activity. Statistical analysis showed no statistical difference between mouth rinses CHX 0.1%, CHX 0.12% and CHX 0.12% + CPC 0.05% (p=0.0001) against C. albicans and R. mucilaginosa. CONCLUSIONS: Mouthwashes with CHX showed higher antifungal activity against C. albicans and R. mucilaginosa than other mouthwashes studied.

Actividad antifúngica de los enjuagues bucales frente a Candida albicans y Rhodotorula mucilaginosa: un estudio in vitro / Antifungal activity of mouthwashes against Candida albicans and Rhodotorula mucilaginosa: an in vitro study

ANTECEDENTES: Candida albicans y Rhodotorula mucilaginosa son levaduras de importancia clínica en la cavidad oral. En pacientes inmunocomprometidos estas levaduras pueden producir enfermedades que deben ser controladas con antimicrobianos. OBJETIVOS: Evaluar y comparar la eficacia antifúngica de seis enjuagues bucales comerciales frente a aislamientos de C. albicans y R. mucilaginosa. MÉTODOS: Fue evaluada in vitro la eficacia de seis enjuagues bucales formulados (solos o en combinación) con clorhexidina (CHX) 0,12%; CHX 0,1%; CHX 0,05%; cloruro de cetilpiridinio (CPC) 0,075%; CPC 0,05% y aceites esenciales. Fueron utilizados diez aislamientos de C. albicans y otros diez de R. mucilaginosa. Mediante el método de difusión en placa con agar Mueller Hinton (modificado) se midieron los halos de inhibición previa incubación a 32°C. RESULTADOS: Los resultados de este estudio indican que enjuagues bucales con CHX 0,1%; CHX 0,12%; CHX 0,05% + CPC 0,05%; CHX 0,12% + CPC 0,05% y CPC 0,075% ejercen un efecto antifúngico frente a C. albicans y R. mucilaginosa. CHX 0,1% dio lugar a la mayor zona de inhibición para C. albicans y R. mucilaginosa (25,65±2,39mm y 40,05±3,31mm). El enjuague con aceites esenciales no tuvo actividad antifúngica alguna. El análisis estadístico no mostró diferencia entre los enjuagues bucales CHX 0,1%; CHX 0,12% y CHX 0,12% + CPC 0,05% (p = 0,0001) frente a C. albicans y R. mucilaginosa. CONCLUSIONES: Los enjuagues bucales con CHX mostraron una mejor actividad antifúngica contra C. albicans y R. mucilaginosa que los restantes enjuagues estudiados

BACKGROUND: Candida albicans and Rhodotorula mucilaginosa are yeasts of clinical importance in the oral cavity. In immunocompromised patients they can cause some pathologies that must be controlled with antimicrobials. AIMS: To evaluate and compare the antimicrobial efficacy of commercially available mouthrinses against strains of C. albicans and R. mucilaginosa. METHODS: The six mouthwashes studied in vitro were formulated (alone or in combination) with chlorhexidine (CHX) 0.12%, CHX 0.1%, CHX 0.05%, cetylpyridinium chloride (CPC) 0.075%, CPC 0.05%, and essential oils. Ten C. albicans and R. mucilaginosa isolates each were studied. The agar diffusion method (Mueller Hinton II), with incubation at 32°C was used to evaluate the antifungal activity. RESULTS: The results of this study indicate that mouthwashes with CHX 0.1%, CHX 0.12%, CHX 0.05% + CPC 0.05%, CHX 0.12% + CPC 0.05% and CPC 0.075% have an antifungal effect against C. albicans and R. mucilaginosa. CHX 0.1% led to the broadest inhibition zone for C. albicans and R. mucilaginosa (25.65±2.39mm and 40.05±3.31mm). Essential oils did not show any antifungal activity. Statistical analysis showed no statistical difference between mouth rinses CHX 0.1%, CHX 0.12% and CHX 0.12% + CPC 0.05% (p = 0.0001) against C. albicans and R. mucilaginosa. CONCLUSIONS: Mouthwashes with CHX showed higher antifungal activity against C. albicans and R. mucilaginosa than other mouthwashes studied

Microencapsulated Bio-Based Rejuvenators for the Self-Healing of Bituminous Materials.

Asphalt self-healing by encapsulated rejuvenating agents is considered a revolutionary technology for the autonomic crack-healing of aged asphalt pavements. This paper aims to explore the use of Bio-Oil (BO) obtained from liquefied agricultural biomass waste as a bio-based encapsulated rejuvenating agent for self-healing of bituminous materials. Novel BO capsules were synthesized using two simple dripping methods through dropping funnel and syringe pump devices, where the BO agent was microencapsulated by external ionic gelation in a biopolymer matrix of sodium alginate. Size, surface aspect, and elemental composition of the BO capsules were characterized by optical and scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermal stability and chemical properties of BO capsules and their components were assessed through thermogravimetric analysis (TGA-DTG) and Fourier-Transform Infrared spectroscopy (FTIR-ATR). The mechanical behavior of the capsules was evaluated by compressive and low-load micro-indentation tests. The self-healing efficiency over time of BO as a rejuvenating agent in cracked bitumen samples was quantified by fluorescence microscopy. Main results showed that the BO capsules presented an adequate morphology for the asphalt self-healing application, with good thermal stability and physical-chemical properties. It was also proven that the BO can diffuse in the bitumen reducing the viscosity and consequently self-healing the open microcracks.

In vitro hemotoxic, α-neurotoxic and vasculotoxic effects of the Mexican black-tailed rattlesnake (Crotalus molossus nigrescens) venom.

The Mexican black-tailed rattlesnake Crotalus molossus nigrescens is distributed in the Mexican plateau. Its venom is known to cause hemolysis and presents fibrinogen coagulase, collagenase and fibrinolytic activities. These activities may be associated with hemostatic alterations, such as platelet aggregation, hemolysis and fibrinolysis, often described in ophidic accidents. However, the mechanisms of action of the C. m. nigrescens venom remain unclear. In this study we investigated the in vitro hemotoxic, neurotoxic, and vasculotoxic effects of the venom. We found that this venom produces two types of hemolytic responses, Oxyhemoglobin release and Methemoglobin formation. As a result of the cytotoxicity to endothelial cells produces morphological biphasic toxicity. The first step in this process is characterized by morphological changes, as well as the loss of cellular adhesion and reduction in thickness. The second phase is characterized by massive cellular aggregation and death. It also induced laminin, type IV collagen, perlecan and nidogen degradation. However, the venom did not modulate the muscular fetal and neuronal nicotinic acetylcholine receptors activity. Thus, we concluded that the C. m. nigrescens venom produced hemolysis and hemorrhages via degradation of the basement membrane components and endothelial cell cytotoxicity, but not by neurotoxicity at the receptor level in nicotinic acetylcholine receptors.