Glycol Solution Research Articles

Experimental study on the preparation of superalloy Inconel718 heat exchanger channels by electrochemical etching method

The nuclear energy field requires the construction of heat exchangers that can withstand sufficiently high temperatures. In this paper, the etching technique was utilized to fabricate heat exchange channels on Inconel718 plates, and experiments were carried out in NaCl-ethylene glycol solution, three temperature conditions of 35 °C, 40 °C, and 45 °C, and two concentrations of electrolyte solutions, 0.5 mol/L and 1 mol/L, with the addition of 50 kHz ultrasound for comparison. The experimental results show that the etching rate can be as high as 2.894 mm/h, and the inter-electrode current is as high as 908 mA. The roughness characterization of the etching channel Ra and Rq measured by the aspheric surface measuring instrument can be as low as 2.416 μm and 2.647 μm, respectively. In the images generated by SEM scanning, it is found that uneven distribution of pits and bumps exist in the etching channel, but their diameters are all less than 0.1 μm, which means the etched channel is acceptably smooth.

Broad-band absorption and photo-thermal conversion characteristics of rGO-Ag hybrid nanofluids

In the current paper, the thermo-physical, optical and photo-thermal conversion characteristics of reduced graphene oxide nanosheets and silver nanoparticles suspended in water and water + ethylene glycol solution (1:1) were experimental investigated under indoor conditions. The results indicated that the hybrid nanofluids have a good solar absorption in both visible and near-infrared regions (220–1400 nm). Comparing transmission spectra and extinction coefficients of rGO-Ag/water and rGO-Ag/W + EG hybrid nanofluids it is found that the use of rGO-Ag/W + EG hybrid nanofluid is much more beneficial than the rGO-Ag/water nanofluid in solar applications. The rGO-Ag /water and rGO-Ag /W + EG hybrid nanofluids with 0.10 wt% exhibit a relative increase in the temperature difference by about 21 % and 37 % compared to the base fluids and also stored energy values of 4989 J and 5432 J respectively, after an irradiation time of 60 min. This study emphasized the solar potential of rGO-Ag hybrid nanofluids for improving the direct absorption solar collectors performance.

Reversible phase transformations between Pb nanocrystals and a viscous liquid-like phase.

Phase transformations have been a prominent topic of study for both fundamental and applied science. Solid-liquid reaction-induced phase transformations can be hard to characterize, and the transformation mechanisms are often not fully understood. Here, we report reversible phase transformations between a metal (Pb) nanocrystal and a viscous liquid-like phase unveiled by in situ liquid cell transmission electron microscopy. The reversible phase transformations are obtained by modulating the electron current density (between 1000 and 3000 electrons Å-2 s-1). The metal-organic viscous liquid-like phase exhibits short-range ordering with a preferred Pb-Pb distance of 0.5 nm. Assisted by density functional theory and molecular dynamics calculations, we show that the viscous liquid-like phase results from the reactions of Pb with the CH3O fragments from the triethylene glycol solution under electron beam irradiation. Such reversible phase transformations may find broad implementations.

Preparation of Controlled Multicompartmental Gel Microcarriers Based on Aqueous Two-Phase Emulsions for 3D Partitioned Cell Coculture In Vitro.

A facile method was proposed for preparing controllable multicompartment gel microcarriers using an aqueous two-phase emulsion system. By leveraging the density difference between the upper polyethylene glycol solution and the lower dextran-calcium chloride (CaCl2) solution in the collection solution and the high viscosity of the lower solution, controllable fusion of core-shell droplets made by coextrusion devices was achieved at the water/water (w/w) interface to fabricate microcarriers with separated core compartments. By adjusting the sodium alginate concentration, collected solution composition, and number of fused liquid droplets, the pore size, shape, and number of compartments could be controlled. Caco-2 and HepG2 cells were encapsulated in different compartments to establish gut-liver coculture models, exhibiting higher viability and proliferation compared to monoculture models. Notably, significant differences in cytokine expression and functional proteins were observed between the coculture and monoculture models. This method provides new possibilities for preparing complex and functional three-dimensional coculture materials.

Advancing BiVO4 Photoanode Activity for Ethylene Glycol Oxidation via Strategic pH Control.

The photoelectrochemical (PEC) conversion of organic small molecules offers a dual benefit of synthesizing value-added chemicals and concurrently producing hydrogen (H2). Ethylene glycol, with its dual hydroxyl groups, stands out as a versatile organic substrate capable of yielding various C1 and C2 chemicals. In this study, we demonstrate that pH modulation markedly enhances the photocurrent of BiVO4 photoanodes, thus facilitating the efficient oxidation of ethylene glycol while simultaneously generating H2. Our findings reveal that in a pH = 1 ethylene glycol solution, the photocurrent density at 1.23 V vs. RHE can attain an impressive 7.1 mA cm-2, significantly surpassing the outputs in neutral and highly alkaline environments. The increase in photocurrent is attributed to the augmented adsorption of ethylene glycol on BiVO4 under acidic conditions, which in turn elevates the activity of the oxidation reaction, culminating in the maximal production of formic acid. This investigation sheds light on the pivotal role of electrolyte pH in the PEC oxidation process and underscores the potential of the PEC strategy for biomass valorization into value-added products alongside H2 fuel generation.

Multimedia Photogrammetry for Automated 3D Monitoring in Archaeological Waterlogged Wood Conservation

Abstract. This study addresses the challenges inherent in preserving archaeological waterlogged wood, which is prone to deformation and decay if not stabilized immediately after recovery. Conventional preservation methods, such as impregnation with polyethylene glycol (PEG) solutions, often result in undesirable dimensional changes. To obtain exact spatio-temporal information on the deformations during the conservation process, a photogrammetric monitoring system, utilizing a stereo camera facing from air into the liquid, attached to an automated biaxial measurement unit is proposed. Special target heads were developed and attached to the wood to provide deformation points. Refraction correction was applied to the imaging model by ray tracing, and indirect flat lighting was used to mitigate turbidity. The system observed logs from a wooden track from the first century, subject to conservation. Subject of investigation were the influence of refraction negligence and scale definition in a bundle geometry, similar to bathymetric aerial setups. Results show that refraction correction is imperative for good results. Furthermore, scale definition with highly accurately determined scale bars and inclusion of relative orientation constraints provide further accuracy improvements.

High‐performance, semi‐bio‐based degradable epoxy resins and their application to recyclable carbon fiber composites

AbstractEpoxy resins containing dynamic covalent networks enable recycling of carbon fiber composites. However, the simultaneous realization of high performance and mild condition recycling of composites is still a challenge. In the present work, we mixed citric acid epoxy resin with bisphenol A epoxy resin to form a hybrid resin (DER) that meets the requirements of medium temperature curing epoxy resin, and prepared a carbon fiber reinforced resin composite material (DER@CF) that can rapidly degrade and recycle carbon fibers under mild conditions. The Tg of the DER was 125.67 °C, and the tensile strength (79.63 MPa) was comparable to that of the bisphenol A epoxy resin (79.90 MPa). It degraded rapidly after 2 h in ethylene glycol solution at 120 °C. The tensile strength of DER@CF was 825 MPa, and clean fibers could be obtained after 8 h of treatment in ethylene glycol solution at 120 °C. The results of SEM, Raman and tensile tests showed that the recycled fibers were similar to the original fibers in terms of morphology, chemical structure and mechanical properties. © 2024 Society of Chemical Industry.

Prediction of bubble departing diameter in pool boiling of mixtures by ANN using modified ReLU

In this research, bubble departure diameter in pool boiling have been measured in aqueous amine and ethylene glycol solutions for various concentrations. The experimental data have been compared with major existing predictive correlations. It is shown that the effect and identity of the independent variables on bubble diameter proposed in the previous studies are inconsistent. The predictions of different correlations have on average a deviation of about 40% from the experimental data. This is mainly due to the complicated interactions between bubbles on the heterogeneous boiling medium, which provides a complex condition. This complexity limits any mathematical modelling of the forces acting on the developing bubbles. Particularly in liquid solutions, where mass transfer by back diffusion through micro-sub-layers adds further complexity. In this work, the classical artificial neural network, ANN, with rectified linear unit, ReLU, activating function, AF, has been modified. This modification is based on adding a numerical matrix to each layer to adjust the slope of AF for each neuron independently. The addition of this parameter, together with the adjustment of the bias matrix, makes the activation function more flexible than the classical ReLU. To find the tuning parameters, a genetic algorithm was implemented instead of the back-propagation technique. It is shown that the predictions of the trained ANN with modified ReLU AF agree within an absolute average error of 10%, which is equal to the total uncertainty of the measurements. Prediction of bubble departing diameter in boiling phenomena is a key parameter for accurate design, operation and optimisation in many industrial systems.

Efficient visible light photocatalytic green hydrogen production from Dy2O3 combined with nitrogen-deficient g-C3N4

The efficient construction of heterojunction photocatalysts has a crucial significance in achieving the decomposition of water for hydrogen generation. This work successfully prepared nitrogen-deficient g-C3N4 (ND-g-C3N4) and combined it with dysprosium oxide (Dy2O3) through high-temperature calcination to create a type II heterojunction photocatalyst (Dy2O3/ND-g-C3N4). Notably, under visible light, the Dy2O3/ND-g-C3N4 photocatalyst demonstrated impressive hydrogen production rates in both ethylene glycol and glucose solutions. Specifically, the photocatalyst achieved H2 generation rates of 463.256 and 510.305 μmol⋅g−1⋅h−1 in ethylene glycol and glucose solutions, respectively. And the quantum yield could be up to 21.76% and 23.96%, respectively. Furthermore, the photocatalytic reforming of glucose for H2 production yielded valuable intermediate products. The f-shell layer in the Dy2O3 had a significant function in enhancing photocatalytic hydrogen production efficiency. This improvement was attributed to the ability of the f-shell layer to capture excited electrons, thereby decreasing the rate of recombination of exciton pairs.

Determining The Crystallite Size of TiO2/EG-Water XRD Data Using the Scherrer Equation

<p class="Abstract">X-ray diffraction (XRD) data and the Scherrer equation were utilized to analyze the crystallite Size of titanium dioxide (TiO<sub>2</sub>) in a solution of ethylene glycol (EG) and distilled water. The XRD analysis was conducted using a Rigaku Miniflex 600 instrument with an X-ray wavelength of approximately 0.15046 nm. The examination yielded the full-width half maximum (FWHM), which was subsequently examined using the Scherrer equation. This experiment employed TiO<sub>2</sub> with a purity level of 99.8% and a crystal Size of 30 nm. The analysis revealed that the average crystallite Size of TiO<sub>2</sub> in the sample is 19.45 nm, with the highest measurement at about 30.38 nm. The Spearman correlation equation was employed to validate the outcomes. The Spearman's correlation coefficient between the FWHM variable and the crystallite Size of TiO<sub>2</sub> nanoparticles is -0.958. These findings shed light on the crystal structure of TiO<sub>2</sub> under these conditions. These findings lend support to the use of TiO<sub>2</sub> in a variety of nanotechnology applications. However, more research is needed to understand fully how crystallite-Size TiO<sub>2</sub> nanoparticles work in different settings and to find the best ways to prepare samples, including understanding the specific phase and how it affects the stability of fluids. This research contributes significantly to the understanding of the properties of TiO<sub>2</sub> in a solution of distilled water and EG, as well as to the characterization of nanomaterials, with particular emphasis on issue 9 of the SDGS Goal concerning industry, innovation, and infrastructure.</p>

Assessment of viscosity effects on high-speed coolant pump performance

The high-speed coolant pump facilitates thermal regulation in electric vehicle components, including batteries and motors, by circulating an ethylene glycol solution. This commonly used circulating fluid exhibits a notable negative correlation with temperature in terms of viscosity. Numerical simulations investigate the transient dynamics of a high-speed coolant pump operating at 6000 rpm, driving coolant flow at various temperatures. A high-speed coolant pump test rig is established, and the performance is evaluated under different temperature conditions. The numerical simulations at different temperatures align well with the experimental outcomes. Decreasing temperatures, from 100 to −20 °C, lead to reduced pump head and efficiency due to increased viscosity. Specifically, at a flow rate of 30 L/min, head decreases by 40.03% and efficiency by 44.19%. With escalating viscosity, the best efficiency point shifts toward lower flow rates. Notable impacts on both disk efficiency and hydraulic efficiency are observed due to viscosity fluctuations. It exerts minimal influence on volumetric efficiency at elevated flow rates but has a substantial impact on volumetric efficiency at lower flow rates. Increased fluid viscosity causes uneven pressure distribution within the pump, altering velocity profiles within the impeller. High-viscosity fluids tend to form large-scale vortex structures around the blades, reducing the thrust exerted by the blades on the fluid. Higher viscosity results in larger vortex structures around the blades, reducing thrust and increasing fluid frictional resistance. The study findings provide valuable insights for the advancement of high-efficiency, energy-saving, high-speed coolant pumps tailored for electric vehicles.

Cryogenic properties of PEG/nano-SiO2 co-toughened winding resin and its carbon fiber-reinforced composites

The epoxy/acid anhydride system was toughened with a homogeneous solution of surface-treated nano-SiO2 and polyethylene glycol (PEG), which satisfies the specific requirements of wet winding processes and effectively enhances the performance of resin and carbon fiber composites at ultra-low temperatures (108K). The results show that when the uniform solution formed by 1 phr SiO2 and 10 phr PEG is added, the tensile strength and elongation at break of the modified resin were increased by 21.4% and 16.1%, respectively, at room temperature. At 108K, the strength and modulus of the modified resin were increased, and the elongation at break was 2.8%. The fracture morphology was analyzed and compared at both room temperature and ultra-low temperature, verifying the relationship between material structure and properties across different temperatures. These findings offer both theoretical and empirical backing for the development of ultra-low temperature carbon fiber composite gas storage tanks.

Appropriate Drought Training Induces Optimal Drought Tolerance by Inducing Stepwise H2O2 Homeostasis in Soybean.

Soybean is considered one of the most drought-sensitive crops, and ROS homeostasis can regulate drought tolerance in these plants. Understanding the mechanism of H2O2 homeostasis and its regulatory effect on drought stress is important for improving drought tolerance in soybean. We used different concentrations of polyethylene glycol (PEG) solutions to simulate the progression from weak drought stress (0.2%, 0.5%, and 1% PEG) to strong drought stress (5% PEG). We investigated the responses of the soybean plant phenotype, ROS level, injury severity, antioxidant system, etc., to different weak drought stresses and subsequent strong drought stresses. The results show that drought-treated plants accumulated H2O2 for signaling and exhibited drought tolerance under the following stronger drought stress, among which the 0.5% PEG treatment had the greatest effect. Under the optimal treatment, there was qualitatively describable H2O2 homeostasis, characterized by a consistent increasing amplitude in H2O2 content compared with CK. The H2O2 signal formed under the optimum treatment induced the capacity of the antioxidant system to remove excess H2O2 to form a primary H2O2 homeostasis. The primary H2O2 homeostasis further induced senior H2O2 homeostasis under the following strong drought and maximized the improvement of drought tolerance. These findings might suggest that gradual drought training could result in stepwise H2O2 homeostasis to continuously improve drought tolerance.

Microfluidic Droplet‐Based Tailorable Porous GelMA Microspheres for 3D Spatio Controllable Cell Coculture

AbstractFor the construction of accurate 3D tissue models in vitro, the 3D coculture model formed by spatio‐controlled distribution of multiple cells is essential. Despite the benefits of porous microspheres with low density, large surface area, and high permeability, exact spatio‐controlled distribution fails to appear in 3D coculture models by using porous microspheres as carriers. Herein, a facile method is proposed to construct a 3D coculture model with heterogeneous cell spatio‐tailored distribution using GelMA microspheres with customizable porosity structure and size based on droplet microfluidics in combination with placeholders. ATPS emulsions, containing two biocompatible immiscible aqueous phases of cell/Alg /dextran (Dex) mixture and polyethylene glycol (PEG) solution, are used as the templates to generate the placeholders. The micron‐sized porous GelMA microspheres are prepared by UV crosslinking of droplets prepared in microfluidic devices, followed by chelation of the placeholders. As a proof of concept, the 3D coculture hepatocellular carcinoma (HCC) model with HepG2 encapsulated outside the pores and HUVEC inside the pores is established. Noteworthy, the cells in the 3D coculture HCC model exhibit greater cell activity and proliferation, enhanced functionalities, and drug resistance than the control group. In conclusion, this straightforward method provides a novel approach for constructing 3D coculture models in vitro.

AgNPs loaded adenine-modified chitosan composite POSS-PEG hybrid hydrogel with enhanced antibacterial and cell proliferation properties for promotion of infected wound healing

Wound healing is a dynamic and complex process, it's urgent to develop new wound dressings with excellent performance to promote wound healing at the different stages. Here, a novel composite hydrogel dressing composed by silver nanoparticles (AgNPs) impregnated adenine-modified chitosan (CS-A) and octafunctionalized polyhedral oligomeric silsesquioxane (POSS) of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) solution was presented to solve the problem of wound infection. Modification of chitosan with adenine, not only can improve the water solubility of chitosan, but also introduce bioactive substances to promote cell proliferation. CS-A and POSS-PEG-CHO were cross-linked by Schiff-base reaction to form the injectable self-healing hydrogel. On this basis, AgNPs were added into the hydrogel, which endows the hydrogel with better antibacterial activity. Moreover, this kind of hydrogel exhibits excellent cell proliferation properties. Studies demonstrated that the hydrogel can significantly accelerate the closure of infected wounds. The histological analysis and immunofluorescence staining demonstrated that the wounds treated with the composite hydrogel exhibited fewer inflammatory cells, more collagen deposition and angiogenesis, faster regeneration of epithelial tissue. Above all, adenine-modified chitosan composite hydrogel with AgNPs loaded was considered as a dressing material with great application potential for promoting the healing of infected wounds.

Experimental investigation of thermophysical properties of propylene glycol based secondary fluids for ground source heat pumps and indirect refrigeration systems

More than 1.7 million ground source heat pumps are currently in operation in the European Union and a large majority of systems is using propylene glycol as secondary fluid. In this study the thermophysical properties of propylene glycol solutions with specific freezing points between −5 and −50 °C are investigated at low temperatures of interest for refrigeration and heat pump applications. The experimentally determined data are compared to a large number of data from the literature. It has been found that the freezing point results for all concentrations were in very good agreement with both Melinder (2010) and ASHRAE (2021) data. Moreover, the literature data and present study for concentrations above 40 wt-% have different density curve slopes compared to ASHRAE data. The viscosity results for concentrations below 40 wt-% were up to 21.5 % higher than ASHRAE data and the viscosity results for solutions with concentrations above 40 wt-% were lower by up to 9.7 %. The thermal conductivity results for concentrations above 40 wt-% were 10 % higher than ASHRAE (2021) data. The experimental specific heat capacity curves and other studies do not have the same linear trend as Melinder (2010) and ASHRAE (2021) data. This difference indicates that currently available ASHRAE data have been indirectly computed from thermal conductivity data or that they have not been fully experimentally validated. Finally, more studies are required to investigate concentrations below 25 wt-% to identify solutions with higher specific heat capacity than water that could be of interest for specific applications.

Polyethylene glycol has immunoprotective effects on sciatic allografts, but behavioral recovery and graft tolerance require neurorrhaphy and axonal fusion.

JOURNAL/nrgr/04.03/01300535-202504000-00033/figure1/v/2024-07-06T104127Z/r/image-tiff Behavioral recovery using (viable) peripheral nerve allografts to repair ablation-type (segmental-loss) peripheral nerve injuries is delayed or poor due to slow and inaccurate axonal regeneration. Furthermore, such peripheral nerve allografts undergo immunological rejection by the host immune system. In contrast, peripheral nerve injuries repaired by polyethylene glycol fusion of peripheral nerve allografts exhibit excellent behavioral recovery within weeks, reduced immune responses, and many axons do not undergo Wallerian degeneration. The relative contribution of neurorrhaphy and polyethylene glycol-fusion of axons versus the effects of polyethylene glycol per se was unknown prior to this study. We hypothesized that polyethylene glycol might have some immune-protective effects, but polyethylene glycol-fusion was necessary to prevent Wallerian degeneration and functional/behavioral recovery. We examined how polyethylene glycol solutions per se affect functional and behavioral recovery and peripheral nerve allograft morphological and immunological responses in the absence of polyethylene glycol-induced axonal fusion. Ablation-type sciatic nerve injuries in outbred Sprague-Dawley rats were repaired according to a modified protocol using the same solutions as polyethylene glycol-fused peripheral nerve allografts, but peripheral nerve allografts were loose-sutured (loose-sutured polyethylene glycol) with an intentional gap of 1-2 mm to prevent fusion by polyethylene glycol of peripheral nerve allograft axons with host axons. Similar to negative control peripheral nerve allografts not treated by polyethylene glycol and in contrast to polyethylene glycol-fused peripheral nerve allografts, animals with loose-sutured polyethylene glycol peripheral nerve allografts exhibited Wallerian degeneration for all axons and myelin degeneration by 7 days postoperatively and did not recover sciatic-mediated behavioral functions by 42 days postoperatively. Other morphological signs of rejection, such as collapsed Schwann cell basal lamina tubes, were absent in polyethylene glycol-fused peripheral nerve allografts but commonly observed in negative control and loose-sutured polyethylene glycol peripheral nerve allografts at 21 days postoperatively. Loose-sutured polyethylene glycol peripheral nerve allografts had more pro-inflammatory and less anti-inflammatory macrophages than negative control peripheral nerve allografts. While T cell counts were similarly high in loose-sutured-polyethylene glycol and negative control peripheral nerve allografts, loose-sutured polyethylene glycol peripheral nerve allografts expressed some cytokines/chemokines important for T cell activation at much lower levels at 14 days postoperatively. MHCI expression was elevated in loose-sutured polyethylene glycol peripheral nerve allografts, but MHCII expression was modestly lower compared to negative control at 21 days postoperatively. We conclude that, while polyethylene glycol per se reduces some immune responses of peripheral nerve allografts, successful polyethylene glycol-fusion repair of some axons is necessary to prevent Wallerian degeneration of those axons and immune rejection of peripheral nerve allografts, and produce recovery of sensory/motor functions and voluntary behaviors. Translation of polyethylene glycol-fusion technologies would produce a paradigm shift from the current clinical practice of waiting days to months to repair ablation peripheral nerve injuries.

Impact of liquid spectrum filter and solar tracker on the overall effectiveness of a photovoltaic thermal system: An experimental investigation

The purpose of this experimental research is to improve the electrical and thermal efficiency of an innovative photovoltaic thermal setup equipped with a Fresnel lens, a nanofluid-based liquid spectrum filter, and a dual-axis solar tracker. The nanofluid, which is a combination of water and ethylene glycol solution with 0.3 wt% of ZnO nanoparticles, was used as a cooling medium. The experiments were conducted on different days that were generally sunny, hazy, and cloudy. The maximum output power of the setup increased by 4.8% and 23.8% from no-lens to single-lens concentration and from a single-stage lens to a two-stage lens concentration system, respectively. The integration of a two-stage system with a solar tracker further enhances the output power by 6.1%. Significant enhancement in the performance of the system was achieved using nanofluid coolant and sun-tracking technologies. The incident solar radiation was efficiently utilized, resulting in an appreciable increase in thermal and electrical efficiency of 6.96% and 28.85%, respectively. Therefore, the proposed system is efficient and suitable for solar photovoltaic thermal applications.

Sodium alginate-polyethylene glycol paste loaded with zinc-doped tricalcium phosphate particles for the treatment of dentin hypersensitivity

β-tricalcium phosphate (β-TCP) has been widely applied in tissue engineering due to its excellent biocompatibility, degradability, and ability to induce mineralization. Zinc ion (Zn2+) displays excellent antibacterial properties and a vital role in regulating cell metabolism. In this context, the incorporation of Zn2+ into β-TCP to prepare Zn-doped β-tricalcium phosphate (Zn-β-TCP), emerges as a promising strategy for treating dentin hypersensitivity. However, delivering Zn-β-TCP effectively to the dentin surface for inducing mineralization of dentinal tubules remains a considerable challenge. In this study, we developed a sodium alginate-polyethylene glycol paste loaded with Zn-β-TCP particles, aiming to deliver Zn-β-TCP to the dentin surface for inducing mineralization. Zn-β-TCP particles were synthesized by the hydrothermal method and were combined with a sodium alginate-polyethylene glycol solution to create the Zn-β-TCP/sodium alginate/polyethylene glycol (Zn-β-TCP/SA/PEG) paste. In vitro experiments demonstrated that Zn-β-TCP could induce mineralization, exert good biocompatibility and antibacterial activity, promote dentin differentiation of dental pulp stem cells. Furthermore, Zn-β-TCP/SA/PEG exhibited excellent viscosity and effectively prompted the formation of a mineralized layer on dentin surfaces, successfully blocking dentinal tubules. Taken together, the present study demonstrated the potential of the Zn-β-TCP/SA/PEG paste as a promising therapeutic material for the treatment of dentin hypersensitivity.

Which Method Is Better for Preserving Meat and Cheese: Coating Propolis on The Packaging Material or Spraying Directly onto The Food?

This study was carried out to determine whether it is better to spray a preservative coating of propolis on the food packaging material or directly onto meat and cheddar cheese. To test this, the surfaces of a vacuum bag (Polyamide/Polyethylene-PA/PE), some stretch film (Low Density Polyethylene- LDPE) and a ziploc bag (Oriented Polypropylene-OPP) and food samples were coated by spraying them with a propolis-ethyl acetate (PEA) solution. Moreover, a propolis-propylene glycol (PPG) solution was sprayed directly on the food surfaces (cheese and meat) to study the shelf life of these products without packaging. Meat and cheddar cheese placed in packages and covered with a PPG solution were stored at 4°C for 30 and 45 days, respectively. The predominant phenolic compound in the propolis used in the study was caffeic acid phenethyl ester (CAPE) at a level of 27.523,4 μg g-1, and the lowest amount of phenolic acid was epigallocatechin gallate at 287.53 μg g-1. At the end of the storage period, the Enterobacteriaceae count of the meat sample stored in propolis sprayed vacuum packaging decreased by 1.01 log CFU g-1 (p˂0.05) compared to the control, and achieved the best result. It was concluded that the PPG solution applied onto the meat did not adhere well to it and the solution could not achieve its antimicrobial effect. At the end of the storage period, while the cheddar cheese sample kept in a propolis-treated vacuum bag had the lowest TMAB count for 21 days (p˂0.05), PPG directly sprayed on cheddar cheese had the lowest TMAB count at the end of storage with 6.64 log CFU g-1 (p˂0.05). The PPG solution was able to adhere to the surface of the cheddar cheese and propolis was able to show its antimicrobial activity. In addition, the LAB (MRS) value for the cheddar cheese sample stored in propolis-treated vacuum packaging decreased by 0.60 log CFU g-1 (p˂0.05) compared to the control and achieved the best result. Microbiological analysis showed that propolis coating in vacuum packaging improved the microbiological quality of the meat and the cheddar cheese.