Optimal Glycerol Concentration Research Articles

Harnessing waste glycerol to mitigate salinity constraints in freshwater microalgae cultivation for enhanced biodiesel recovery

The current study investigated the synergistic effect of waste glycerol and salinity on Scenedesmus obliquus cultivation for enhanced biomass and biodiesel production. Optimal glycerol concentration was identified at 0.08 M supplementation, resulting in 23.1 % significant increase in biomass productivity. However, higher glycerol concentrations resulted in growth retardation. Salinity of +200 % NaCl showed positive impact on the growth, with the highest recorded dry weight of 1.76 g/L and biomass productivity of 0.206 g/L.day. However, further increases in salinity resulted in 53.4 % reduction in biomass yield at +800 % NaCl compared to +200 % NaCl. The combined treatment of the optimum glycerol concentration at different salinities (Glyc + Salin) showed superior growth performance up to +600 % NaCl, which confirmed mitigation of salinity inhibitory effects. Glyc + Salin exhibited the highest recorded nitrogen and phosphorus removal efficiencies (98.1 % and 96.6 %, respectively at day 8), dry weight (2.02 g/L), and biomass productivity (0.231 g/L.day). Notably, lipid content increased to 240.4 mg/g dw, and lipid productivity reached 56.0 mg/L.day, representing 76.1 % improvement over the control. Biodiesel characteristics, including cetane numbers and iodine values, showed also improvement, confirming the potential of Glyc + Salin for sustainable microalgal cultivation and biodiesel production.

Physical Quality Of Edible Film From Duck Feet Gelatin Using Various Glycerol Concentrations

Edible film is a type of packaging that can be consumed, can coat food products, and can be decomposed naturally (biodegradable). This research aims to assess the effect of applying glycerol on the physical quality of edible film from duck's feet gelatin. This research used a completely randomized design (CRD) followed by the Tukey test. The treatment was the use of 10% (T1), 20% (T2), 30% (T3), 40% (T4), and 50% (T5) glycerol. The treatments were repeated three times. The findings indicated that the use of glycerol had a significant difference in the yield, thickness, tensile strength, and Young's modulus of edible film (P<0.05), but was not significantly different in the elongation of edible film (P>0.05). The optimal glycerol concentration for edible film in this study was obtained by using 10% glycerol.

Utilization of Duck Feet Gelatin with the Additional Glycerol as A Plasticizer on the Physical Properties of Edible Film

The packaging that is widely used is plastic packaging, but this material has a weakness that is difficult to decompose and isn’t biodegradable, therefore edible film can be an alternative primary packaging for food products. The material used consists of gelatine made from duck feet with the addition of various concentrations of glycerol. Duck feet is an underutilized portion of the animal's anatomy, yet they contain collagen, which has the potential to be the raw material for gelatine and edible films. The study was undertaken utilizing duck feet as a source of raw material, which was subsequently processed into gelatine for use in the production of edible films using different glycerol treatments. The treatments comprised of glycerol concentrations of P1 = 10%, P2 = 20%, P3 = 30%, P4 = 40%, P5 = 50%, and P6 = 60%. The findings indicated that the application of glycerol significantly affected the films' solubility, water absorption, and tensile strength (P<0.05), but didn’t significantly affect the elongation of edible films. (P>0.05). The optimal concentration of glycerol for edible film in this study was obtained by using 20% glycerol, with a physical characteristic value of 40.25% solubility, 24.23% water absorption, tensile strength is 0.57 MPa, and elongation is 90%.

Effect of Glycerol on an N-Vinylpyrrolidone-Based Photopolymer for Transmission Holography.

N-vinylpyrrolidone (NVP) has a large molecular structure, so it is difficult to diffuse during holographic recording, especially at low spatial frequencies. We used glycerol to promote the diffusion of NVP, and successfully improved the holographic performance of the photopolymer at low spatial frequencies. As the concentration of glycerol increases, the holographic performance first increases and then remains stable. The optimal concentration of glycerol is 0.21 mol/L. At this concentration, the maximum diffraction efficiency of the photopolymer is 84%, the refractive index modulation is 1.95 × 10−3, and the photosensitive sensitivity is 7.91 × 10−4 cm2/mJ. Compared with the control group, the maximum diffraction efficiency, maximum refractive index modulation and photosensitivity at low spatial frequencies (800 lp/mm) have increased by 11.19 times, 4.69 times and 1.71 times, respectively. Using the optimized photopolymer for transmission holographic recording and reproduction, we have obtained a clear and bright transmission hologram. The photopolymer modified with glycerol is expected to be applied to the fields of holography, diffractive optics, and so on.

Optimización estadística del medio de cultivo de una bacteria del género Pseudomonas sp. para la producción de biosurfactantes

El objetivo del presente trabajo es obtener la temperatura y concentración de glicerol óptima en el medio de cultivo utilizado para la producción de biosurfactantes a partir de una cepa de Pseudomonas sp. La optimización se llevó a cabo a través de una metodología de superficie de respuesta utilizando un diseño central compuesto centrado en las caras, donde concentración de glicerol y temperatura fueron los factores y concentración de biosurfactante la respuesta. Se halló un modelo matemático basado en los resultados experimentales que permite predecir la influencia de los factores en la producción de biosurfactantes. De acuerdo con dicho modelo, una concentración de 7,6%v/v y una temperatura de 25,9°C harían máxima la respuesta. En estas condiciones dicha respuesta tendría un valor de 0,43g/l.

Effect of glycerol on the mechanical and temperature-sensing properties of pectin films

Temperature-sensitive films embedded in electronic skins (e-skins) can provide temperature feedback to robots, high-tech prostheses, and wearable devices for health care monitoring. Pectin-based films have shown a temperature response at least two orders of magnitude higher than previously reported temperature-sensing materials. However, they are not easily stretchable and tearable, which limit their applications as e-skins that require repetitive bending and mechanical stresses. Here, we show how the addition of glycerol as a plasticizer in the fabrication of pectin-based films improves their mechanical properties. We report how the enhancement of the mechanical performance is accompanied by a decrease in the temperature responsivity. Through thermogravimetric analysis, we show that this reduction in responsivity can be associated with water retention due to the addition of the plasticizer. The link between the water content and the temperature response demonstrates that a dehydrated status of pectin is crucial to record its high temperature responsivity. Combining electrical and thermal characterization with the tensile strength test, we estimate the optimal concentration of glycerol for improving the mechanical properties without compromising the temperature response of the pectin films.

Chemical and biological conversion of crude glycerol derived from waste cooking oil to biodiesel

In this study, crude, purified, and pure glycerol were used to cultivate Trichosporon oleaginosus for lipid production which was then used as feedstock of biodiesel production. The purified glycerol was obtained from crude glycerol by removing soap with addition of H3PO4 which converted soap to free fatty acids and then separated from the solution. The results showed that purified glycerol provided similar performance as pure glycerol in lipid accumulation; however, crude glycerol as carbon source had negatively impacted the lipid production of T. oleaginosus. Purified glycerol was later used to determine the optimal glycerol concentration for lipid production. The highest lipid yield 0.19g/g glycerol was obtained at 50g/L purified glycerol in which the biomass concentration and lipid content were 10.75g/L and 47% w/w, respectively. An energy gain of 4150.51MJ could be obtained with 1tonne of the crude glycerol employed for biodiesel production through the process proposed in this study. The biodiesel production cost estimated was 6.32US$/gal. Fatty acid profiles revealed that C16:0 and C18:1 were the major compounds of the biodiesel from the lipid produced by T. oleaginosus cultivated with crude and purified glycerol. The study found that purified glycerol was promising carbon source for biodiesel production.

Determinación de la Concentración Óptima de Tres Crioprotectores para la Criopreservación de Espermatozoides Epididimarios de Alpaca

El objetivo del presente estudio fue determinar la concentración óptima de glicerol, etilenglicol y dimetil sulfóxido (DMSO) en la criopreservación de espermatozoides epididimarios de alpaca. En el experimento 1 se evaluó el efecto de ocho concentraciones de glicerol, etilenglicol y DMSO: T1 (0 M), T2 (0.25 M), T3 (0.5 M), T4 (0.75 M), T5 (1 M), T6 (1.25 M), T7 (1.5 M) y T8 (1.75 M). Se utilizó un modelo de regresión polinomial quíntuple para determinar la mejor concentración de cada crioprotector, resultando concentraciones óptimas para glicerol, etilenglicol y DMSO de 1.16, 1.02 y 0.9 M, respectivamente. En el Experimento 2, se comparó el efecto de las concentraciones óptimas entre glicerol, etilenglicol y DMSO sobre la motilidad, integridad de membrana plasmática y viabilidad e integridad acrosomal en los espermatozoides epididimarios de alpaca. Los resultados mostraron promedios de 35.8, 51.8 y 38.3% para DMSO (0.9 M) y de de 30.8, 45.0 y 33.8% para glicerol para las variables motilidad, integridad de membrana plasmática y viabilidad e integridad acrosomal, respectivamente, y sin diferencias significativas entre estos crioprotectores. Sin embargo, fueron significativamente mejores (p<0.05) que para etilenglicol (1.02 M). Se concluye que las concentraciones de 0.9 M de DMSO y 1.16 M de glicerol conservaron mejor las características funcionales de los espermatozoides epididimarios de alpaca en comparación con etilenglicol (1.02 M).

Use of Crude Glycerol as Sole Carbon Source for Microbial Lipid Production by Oleaginous Yeasts.

Crude glycerol, discharged from biodiesel production process, is a potential carbon source for microbial lipid production. The capability of using crude glycerol as sole carbon source for microbial lipid production by oleaginous yeasts Trichosporon fermentans and Trichosporon cutaneum was investigated for the first time. T. fermentans and T. cutaneum could use crude glycerol for efficient lipid production, and the optimal glycerol concentration for which were 50 and 70g/L, respectively. The optimum nitrogen source, C/N, inoculum concentration, and pH were yeast extract + peptone, 60, 10.0%, and 6.0, respectively. The most suitable culture temperature for T. fermentans and T. cutaneum were 28 and 30°C, respectively. Under the optimal conditions, the maximum biomass, lipid content, lipid yield, and lipid coefficient of T. fermentans and T. cutaneum were 16.0g/L, 32.4%, 5.2g/L, and 16.5%, and 17.4g/L, 32.2%, 5.6g/L, and 17.0%, respectively. Moreover, it was found that methanol present in the crude glycerol had minor influence on the lipid production. Addition of surfactant potassium oleate into the medium could slightly stimulate the cell growth and lipid accumulation of both yeasts. This study shows that T. fermentans and T. cutaneum are promising strains for lipid production on crude glycerol.

Simulation of Aqueous Blend of Monoethanolamine and Glycerol for Carbon Dioxide Capture from Flue Gas

This study investigated CO2 capture from flue gas by using glycerol as solvent. Absorption was simulated using a rate-based model with three cases under similar operating conditions. CO2 separation was first simulated using ENRTL-RK thermodynamic model with monoethanolamine (MEA) as solvent. CO2 absorption was then simulated using NRTL-RK thermodynamic model with glycerol solvent, and then an aqueous mixture of MEA/glycerol was also simulated using ENRTL-RK thermodynamic model. Simulation results confirm that glycerol can be used as promoter with MEA solvent to enhance CO2 capture. The optimal glycerol concentration for CO2 absorption is 10–40 wt %, in which 10 wt % glycerol exhibits the lowest CO2 concentration in the outlet gas from the absorber. The CO2 removal efficiency increases from 62.24% for 10 wt % MEA aqueous solution to 64.33% for the mixture of 10 wt % MEA–10 wt % glycerol aqueous solution. The CO2 removal efficiency for 10 wt % glycerol aqueous solution is 27.31%.

Elucidating the Effect of Glycerol Concentration and C/N Ratio on Lipid Production Using Yarrowia lipolytica SKY7

The high demand for renewable energy and increased biodiesel production lead to the surplus availability of crude glycerol. Due to the above reason, the bio-based value addition of crude glycerol into various bioproducts is investigated; among them, microbial lipids are attractive. The present study was dedicated to find the optimal glycerol concentration and carbon/nitrogen (C/N) ratio to produce maximum lipid using Yarrowia lipolytica SKY7. The glycerol concentration (34.4 to168.2g/L) and C/N ratio (25 to 150) were selected to investigate to maximize the lipid production. Initial glycerol concentration 112.5g/L, C/N molar ratio of 100, and with 5%v/v inoculum supplementation were found to be optimum for biomass and lipid production. Based on the above optimal parameters, lipid concentration of 43.8%w/w with a biomass concentration of 14.8g/L was achieved. In the case of glycerol concentration, the maximum Yp/s (0.192g/g); Yx/s (0.43g/g) was noted when the initial glycerol concentration was 112.5g/L with C/N molar ratio 100 and inoculum volume 5%v/v. The glycerol uptake was also noted to increase with the increase in glycerol concentration. At low C/N ratio, the glycerol consumption was found to be high (79.43g/L on C/N 25) whereas the glycerol consumption was observed to decrease when the C/N ratio was raised to 150 (40.8g/L).

Succinic Acid Production in Fed‐Batch Fermentation of Anaerobiospirillum succiniciproducens Using Glycerol as Carbon Source

AbstractConsidering glycerol as an inexpensive alternative carbon source, the optimal glycerol concentration for succinic acid production with Anaerobiospirillum succiniciproducens was identified in shake‐flask trials. The addition of a defined amount of glucose improved the growth and succinic acid productivity significantly. In fed‐batch processes with glycerol as sole substrate, a maximum succinic acid concentration and product substrate yield were obtained. The addition of glucose led to a 2.5‐fold increased succinic acid concentration whereas the product substrate yield remained nearly constant.

Cross-evaluation of optimal glycerol concentration to enhance optical tissue clearing efficacy.

The efficacy of light therapeutic and diagnostic applications can be enhanced by employing optical tissue clearing (OTC) agents to minimize light scattering in tissue. This study aimed to investigate the optimal concentration of glycerol, so that it can be efficiently used as an OTC agent in dermatology. Glycerol was topically applied to avoid the possibility of edema that could be caused by dermal injection. The efficacy of glycerol was quantitatively evaluated for various concentrations using optical coherence tomography (OCT) to evaluate light scattering and ultrasound imaging modality to evaluate collagen dissociation. The intensity in the OCT images in the deeper regions increased over time after glycerol application owing to enhanced light penetration caused by glycerol permeation into the sample. A comparable decrease over time in the collagen distribution was observed in the ultrasound images after glycerol application. The optimal concentration of glycerol to maximize OTC was found to be 70%. The finding of this study may provide a guideline regarding the use of glycerol for efficient light diagnosis and therapy in dermatology.

Effects of sub-optimal glycerol concentration and cholesterol-loaded cyclodextrin in a Tris-based diluent on cryopreserved ram sperm longevity and acrosomal integrity

The maintenance of motility, viability and acrosomal integrity of ram spermatozoa for an extended period of time after cryopreservation is important for achieving high pregnancy rates, when using frozen–thawed semen. The most frequently used cryoprotectant is glycerol, which has to be used at low concentrations (under 4%), due to its potential toxicity. The primary objective of this study was to determine the combined effect of sub-optimal glycerol inclusion and cholesterol-loaded cyclodextrin (CLC) in a Tris-based diluent on ram spermatozoal longevity and acrosomal integrity during in vitro incubation, after cryopreservation. Ram semen was treated with 0 or 2mgCLC/100×106cells in Tris-based diluents containing either 6 or 3% glycerol and frozen in 0.5ml straws. After thawing, the responses of all sperm parameters recorded were not significantly different between sub-optimal glycerol concentration (3%) and optimal glycerol concentration (6%) for untreated semen groups (0mgCLC/100×106). Similarly, no significant differences were recorded between glycerol concentrations when semen samples were treated with 2mgCLC/100×106cells prior to cryopreservation. However, sperm treated with CLC prior to cryopreservation in diluents containing a sub-optimal concentration of glycerol (3%), recorded significantly higher (P<0.05) percentages of total motile sperm, progressive motility, viability and acrosomal integrity, than for optimal glycerol concentrations (6%) for up to 4h of in vitro incubation, at 38.5°C after cryopreservation and thawing. Results suggest that in ram spermatozoa, a combination of 2mg cholesterol-loaded cyclodextrins (CLC)/100×106 and a sub-optimal concentration of glycerol (3%) in a Tris-based diluent helps to reduce the acrosomal damage observed during cryopreservation, maintaining sperm viability and motility.

Optimization of Glycerol Concentration and Freezing Rate in the Cryopreservation of Ejaculate From Brown Bear (Ursus arctos)

In order to establish a semen bank for the endangered Cantabrian brown bear, we tested five glycerol concentrations and three freezing rates for electroejaculated semen. Electroejaculation was performed on nine males. Semen was diluted in TES-Tris-Fructose (20% egg yolk, 2% EDTA, 1% Equex) with 2%, 4%, 6%, 8% or 10% glycerol and frozen at -10, -20 or -40°C/min. Before and after cryopreservation, samples were analysed for motility (CASA), viability and acrosomal status (flow cytometry). Pre-freezing results showed that glycerol concentration had no significant effect on total motility or progressive motility, but it significantly decreased VCL, ALH, viability and acrosomal status (p < 0.05). After thawing, sperm motility was higher at extender with 4%, 6% and 8% glycerol, but only at 4% and 6% glycerol for viability and acrosomal status. For 4% and 6% glycerol, freezing rates did not have significant effects. The curve fitting gave an estimate of the optimal glycerol concentration, with all the optimal values for every parameter between 6% and 7% glycerol falling. We propose using 6% glycerol and a freezing velocity of -20°C/min for freezing brown bear ejaculated spermatozoa.

A physical method to enhance transdermal delivery of a tissue optical clearing agent: Combination of microneedling and sonophoresis

Various physical methods, such as microneedling, laser ablation, sonophoresis, and sandpaper, have been widely studied to enhance the transdermal delivery of tissue optical clearing (TOC) agents. A previous study demonstrated that the microneedling method could effectively enhance the permeability of a TOC agent through the skin barrier. In this study, we introduce a new physical combination method which utilizes both microneedling and sonophoresis to further enhance the transdermal delivery of a TOC agent, glycerol. Porcine skin samples were divided into a control group treated only with the microneedle roller and a test group treated with both the microneedle roller and sonophoresis. Glycerol was applied topically after microneedling. The optimal concentration and transdermal delivery efficacy of glycerol were quantitatively evaluated. A 70% glycerol solution was determined to be the optimal concentration for the combination method. The combination method resulted in approximately a 2.3-fold higher transdermal diffusion rate of glycerol when compared to the microneedling method alone. The combination method and optimal glycerol concentration effectively enhanced transdermal delivery of glycerol by accelerating the diffusion rate through the skin barrier.

Combined effect of liposomalization and addition of glycerol on the transdermal delivery of isosorbide 5-nitrate in rat skin

In this report, we investigated the combined effect of drug liposomalization and addition of glycerol on the transdermal delivery of isosorbide 5-nitrate (ISN) in rat abdominal skin in vitro. Occlusive application of both liposomal and aqueous ISN solution, with and without addition of 5% glycerol, showed that drug liposomalization and addition of glycerol has far-reaching implications for ISN permeation and accumulation in 4 and 8 weeks old rat abdominal skin. Using 8 weeks old rat abdominal skin, the optimal concentration of glycerol to be added to liposomal ISN was found to be 5%. The ISN mean values permeated through and accumulated in stripped 8 weeks old rat abdominal skin from those formulations described above were not significant different, which might indicate the combined effect of glycerol and liposomal ISN resides solely in the stratum corneum (SC). Based on previous reports, the enhancement effect of glycerol might be due to an increase in the SC hydration, and perhaps due to subtle changes in the lipid organization caused by penetration of liposomal lipids within the SC intercellular spaces. These data might provide evidence that glycerol action on SC is useful to facilitate skin permeation and accumulation of drugs formulated in liposome.

Mixotrophic growth of Phaeodactylum tricornutum on glycerol: growth rate and fatty acid profile

Mixotrophic growth of the eicosapentaenoic acid (EPA)producing diatom Phaeodactylum tricornutum UTEX640 was carried out in 1-L batch cultures under anexternal irradiance of 165 μmol photons m-2s-1 by supplementing the inorganic culture mediumwith glycerol. The effect on the growth and the fattyacid profile was studied for different initialglycerol concentrations (0–0.1 M). The optimalglycerol concentration was 0.1 M.A lag phase was observed at high glycerolconcentrations. The present study also shows thatsuccessive additions of glycerol at 0.1M concentrationand using ammonium chloride as a nitrogen sourceremarkably increased the maximum biomass concentration(16.2 g L-1) and maximum biomass productivity(61.5 mg L-1 h-1). These values wererespectively 9 and 8-fold higher than in thephotoautotrophically grown control. The level ofsaponifiable lipids in mixotrophically cultured cellswas significantly higher than in photoautotrophicallycultured cells and increased with the glycerolconcentration in the medium. The concentration ofstorage lipids, saturated and monounsaturated fattyacids, were enhanced but the EPA content did notchange significantly. The EPA content was around 2.2%of biomass dry weight. The maximum EPA yield was33.5 mg L-1 d-1 and was obtained in aculture containing 0.1 M glycerol, supplementedperiodically by ammonium chloride. This productivitywas 10-fold higher than the EPA productivity obtainedunder mixotrophic conditions.

The afterdepolarization in Rana temporaria muscle fibres following osmotic shock

Rana temporaria sartorius muscle fibres were exposed to varied sequences of solution and temperature changes that have been employed hitherto in procedures that sought to decouple the transverse tubules from the surface membrane. The incidence of such detubulation was assessed in large numbers of fibres through demonstrating a loss or otherwise of the after-depolarization that normally reflects successful tubular propagation of the surface action potential. This criterion yielded assessments of the existing detubulation techniques in agreement with earlier results. The experiments then developed an improved detubulation procedure that required only brief (15 min) exposures to glycerol, its replacement in a single step by a Ca2+/Mg(2+)-Ringer solution for 30 min, and rapid cooling from room temperature (19-21 degrees C) to 6-10 degrees C prior to final restoration of the normal Ringer solution. This sequence of steps yielded an optimal incidence (98%) of detubulation in viable surface fibres that were amenable to electrophysiological studies. Studies that systematically modified the detubulation procedure demonstrated that the omission of any one step in the protocol significantly reduced the incidence of detubulation with or without accompanying deteriorations in fibre resting potentials. Successful detubulation accordingly required an initial exposure to an optimal glycerol concentration that lasted for a minimal duration and for its abrupt withdrawal. Inclusion of a cooling step within 30 min after glycerol withdrawal was coincident with, and critical to, optimal tubular isolation. Thus, cooling steps that either preceded, or that followed the glycerol withdrawal step by more than 60 min, resulted in a sharp reduction in the incidence of detubulation. Similarly, a critical period of exposure to Ca2+/Mg2+ Ringer solution also promoted detubulation without compromising the recovery of stable and satisfactory resting potentials. The findings reported here remain consistent with a primarily osmotic mechanism for detubulation. However, they demonstrated additional and important influences of temperature and of divalent cation concentration on the extent of tubular detachment when such factors were modified during the time course of the expected volume changes that followed each adjustment in osmotic condition.

Computerized analysis of sperm motion: Effects of glycerol concentration on the cryopreservation of equine spermatozoa

Summary An experiment was conducted to examine the effects of glycerol added to a glucose-sucrose-dried skim milk freezing extender (B4) at 0, 1, 2, or 4% for cryopreservation of equine spermatozoa. Two ejaculates from each of three stallions were used in the study. Following cryopreservation and storage in liquid nitrogen for at least 30 days, the semen was thawed and subsequently diluted to approximately 33 × 10 6 sperm/ml in the freezing extender minus glycerol and egg yolk at 30°C. It was then incubated for 1 h at room temperature prior to evaluation. Each semen sample was evaluated for the percentage of motile sperm (M, %), the percentage progressively motile sperm (PM, %), velocity (V, μ/sec), progressive velocity (PV, μ/sec), linearity (L, %) and lateral head displacement (LHD, μ) using computer-aided sperm analysis (CASA). The data were statistically analyzed and the optimal glycerol concentration was determined for each parameter. For three of the parameters (M, PM and LHD), the 2% level of glycerol was selected by the statistical analysis as optimal (P